linux/include/uapi/linux/bpf.h
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   1/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
   2/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
   3 *
   4 * This program is free software; you can redistribute it and/or
   5 * modify it under the terms of version 2 of the GNU General Public
   6 * License as published by the Free Software Foundation.
   7 */
   8#ifndef _UAPI__LINUX_BPF_H__
   9#define _UAPI__LINUX_BPF_H__
  10
  11#include <linux/types.h>
  12#include <linux/bpf_common.h>
  13
  14/* Extended instruction set based on top of classic BPF */
  15
  16/* instruction classes */
  17#define BPF_JMP32       0x06    /* jmp mode in word width */
  18#define BPF_ALU64       0x07    /* alu mode in double word width */
  19
  20/* ld/ldx fields */
  21#define BPF_DW          0x18    /* double word (64-bit) */
  22#define BPF_XADD        0xc0    /* exclusive add */
  23
  24/* alu/jmp fields */
  25#define BPF_MOV         0xb0    /* mov reg to reg */
  26#define BPF_ARSH        0xc0    /* sign extending arithmetic shift right */
  27
  28/* change endianness of a register */
  29#define BPF_END         0xd0    /* flags for endianness conversion: */
  30#define BPF_TO_LE       0x00    /* convert to little-endian */
  31#define BPF_TO_BE       0x08    /* convert to big-endian */
  32#define BPF_FROM_LE     BPF_TO_LE
  33#define BPF_FROM_BE     BPF_TO_BE
  34
  35/* jmp encodings */
  36#define BPF_JNE         0x50    /* jump != */
  37#define BPF_JLT         0xa0    /* LT is unsigned, '<' */
  38#define BPF_JLE         0xb0    /* LE is unsigned, '<=' */
  39#define BPF_JSGT        0x60    /* SGT is signed '>', GT in x86 */
  40#define BPF_JSGE        0x70    /* SGE is signed '>=', GE in x86 */
  41#define BPF_JSLT        0xc0    /* SLT is signed, '<' */
  42#define BPF_JSLE        0xd0    /* SLE is signed, '<=' */
  43#define BPF_CALL        0x80    /* function call */
  44#define BPF_EXIT        0x90    /* function return */
  45
  46/* Register numbers */
  47enum {
  48        BPF_REG_0 = 0,
  49        BPF_REG_1,
  50        BPF_REG_2,
  51        BPF_REG_3,
  52        BPF_REG_4,
  53        BPF_REG_5,
  54        BPF_REG_6,
  55        BPF_REG_7,
  56        BPF_REG_8,
  57        BPF_REG_9,
  58        BPF_REG_10,
  59        __MAX_BPF_REG,
  60};
  61
  62/* BPF has 10 general purpose 64-bit registers and stack frame. */
  63#define MAX_BPF_REG     __MAX_BPF_REG
  64
  65struct bpf_insn {
  66        __u8    code;           /* opcode */
  67        __u8    dst_reg:4;      /* dest register */
  68        __u8    src_reg:4;      /* source register */
  69        __s16   off;            /* signed offset */
  70        __s32   imm;            /* signed immediate constant */
  71};
  72
  73/* Key of an a BPF_MAP_TYPE_LPM_TRIE entry */
  74struct bpf_lpm_trie_key {
  75        __u32   prefixlen;      /* up to 32 for AF_INET, 128 for AF_INET6 */
  76        __u8    data[0];        /* Arbitrary size */
  77};
  78
  79struct bpf_cgroup_storage_key {
  80        __u64   cgroup_inode_id;        /* cgroup inode id */
  81        __u32   attach_type;            /* program attach type */
  82};
  83
  84/* BPF syscall commands, see bpf(2) man-page for details. */
  85enum bpf_cmd {
  86        BPF_MAP_CREATE,
  87        BPF_MAP_LOOKUP_ELEM,
  88        BPF_MAP_UPDATE_ELEM,
  89        BPF_MAP_DELETE_ELEM,
  90        BPF_MAP_GET_NEXT_KEY,
  91        BPF_PROG_LOAD,
  92        BPF_OBJ_PIN,
  93        BPF_OBJ_GET,
  94        BPF_PROG_ATTACH,
  95        BPF_PROG_DETACH,
  96        BPF_PROG_TEST_RUN,
  97        BPF_PROG_GET_NEXT_ID,
  98        BPF_MAP_GET_NEXT_ID,
  99        BPF_PROG_GET_FD_BY_ID,
 100        BPF_MAP_GET_FD_BY_ID,
 101        BPF_OBJ_GET_INFO_BY_FD,
 102        BPF_PROG_QUERY,
 103        BPF_RAW_TRACEPOINT_OPEN,
 104        BPF_BTF_LOAD,
 105        BPF_BTF_GET_FD_BY_ID,
 106        BPF_TASK_FD_QUERY,
 107        BPF_MAP_LOOKUP_AND_DELETE_ELEM,
 108        BPF_MAP_FREEZE,
 109        BPF_BTF_GET_NEXT_ID,
 110        BPF_MAP_LOOKUP_BATCH,
 111        BPF_MAP_LOOKUP_AND_DELETE_BATCH,
 112        BPF_MAP_UPDATE_BATCH,
 113        BPF_MAP_DELETE_BATCH,
 114        BPF_LINK_CREATE,
 115        BPF_LINK_UPDATE,
 116};
 117
 118enum bpf_map_type {
 119        BPF_MAP_TYPE_UNSPEC,
 120        BPF_MAP_TYPE_HASH,
 121        BPF_MAP_TYPE_ARRAY,
 122        BPF_MAP_TYPE_PROG_ARRAY,
 123        BPF_MAP_TYPE_PERF_EVENT_ARRAY,
 124        BPF_MAP_TYPE_PERCPU_HASH,
 125        BPF_MAP_TYPE_PERCPU_ARRAY,
 126        BPF_MAP_TYPE_STACK_TRACE,
 127        BPF_MAP_TYPE_CGROUP_ARRAY,
 128        BPF_MAP_TYPE_LRU_HASH,
 129        BPF_MAP_TYPE_LRU_PERCPU_HASH,
 130        BPF_MAP_TYPE_LPM_TRIE,
 131        BPF_MAP_TYPE_ARRAY_OF_MAPS,
 132        BPF_MAP_TYPE_HASH_OF_MAPS,
 133        BPF_MAP_TYPE_DEVMAP,
 134        BPF_MAP_TYPE_SOCKMAP,
 135        BPF_MAP_TYPE_CPUMAP,
 136        BPF_MAP_TYPE_XSKMAP,
 137        BPF_MAP_TYPE_SOCKHASH,
 138#ifndef __GENKSYMS__
 139        BPF_MAP_TYPE_CGROUP_STORAGE,
 140        BPF_MAP_TYPE_REUSEPORT_SOCKARRAY,
 141        BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE,
 142        BPF_MAP_TYPE_QUEUE,
 143        BPF_MAP_TYPE_STACK,
 144        BPF_MAP_TYPE_SK_STORAGE,
 145        BPF_MAP_TYPE_DEVMAP_HASH,
 146        BPF_MAP_TYPE_STRUCT_OPS,
 147#endif /* __GENKSYMS__ */
 148};
 149
 150/* Note that tracing related programs such as
 151 * BPF_PROG_TYPE_{KPROBE,TRACEPOINT,PERF_EVENT,RAW_TRACEPOINT}
 152 * are not subject to a stable API since kernel internal data
 153 * structures can change from release to release and may
 154 * therefore break existing tracing BPF programs. Tracing BPF
 155 * programs correspond to /a/ specific kernel which is to be
 156 * analyzed, and not /a/ specific kernel /and/ all future ones.
 157 */
 158enum bpf_prog_type {
 159        BPF_PROG_TYPE_UNSPEC,
 160        BPF_PROG_TYPE_SOCKET_FILTER,
 161        BPF_PROG_TYPE_KPROBE,
 162        BPF_PROG_TYPE_SCHED_CLS,
 163        BPF_PROG_TYPE_SCHED_ACT,
 164        BPF_PROG_TYPE_TRACEPOINT,
 165        BPF_PROG_TYPE_XDP,
 166        BPF_PROG_TYPE_PERF_EVENT,
 167        BPF_PROG_TYPE_CGROUP_SKB,
 168        BPF_PROG_TYPE_CGROUP_SOCK,
 169        BPF_PROG_TYPE_LWT_IN,
 170        BPF_PROG_TYPE_LWT_OUT,
 171        BPF_PROG_TYPE_LWT_XMIT,
 172        BPF_PROG_TYPE_SOCK_OPS,
 173        BPF_PROG_TYPE_SK_SKB,
 174        BPF_PROG_TYPE_CGROUP_DEVICE,
 175        BPF_PROG_TYPE_SK_MSG,
 176        BPF_PROG_TYPE_RAW_TRACEPOINT,
 177        BPF_PROG_TYPE_CGROUP_SOCK_ADDR,
 178        BPF_PROG_TYPE_LWT_SEG6LOCAL,
 179        BPF_PROG_TYPE_LIRC_MODE2,
 180#ifndef __GENKSYMS__
 181        BPF_PROG_TYPE_SK_REUSEPORT,
 182        BPF_PROG_TYPE_FLOW_DISSECTOR,
 183        BPF_PROG_TYPE_CGROUP_SYSCTL,
 184        BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE,
 185        BPF_PROG_TYPE_CGROUP_SOCKOPT,
 186        BPF_PROG_TYPE_TRACING,
 187        BPF_PROG_TYPE_STRUCT_OPS,
 188        BPF_PROG_TYPE_EXT,
 189        BPF_PROG_TYPE_LSM,
 190#endif /* __GENKSYMS__ */
 191};
 192
 193enum bpf_attach_type {
 194        BPF_CGROUP_INET_INGRESS,
 195        BPF_CGROUP_INET_EGRESS,
 196        BPF_CGROUP_INET_SOCK_CREATE,
 197        BPF_CGROUP_SOCK_OPS,
 198        BPF_SK_SKB_STREAM_PARSER,
 199        BPF_SK_SKB_STREAM_VERDICT,
 200        BPF_CGROUP_DEVICE,
 201        BPF_SK_MSG_VERDICT,
 202        BPF_CGROUP_INET4_BIND,
 203        BPF_CGROUP_INET6_BIND,
 204        BPF_CGROUP_INET4_CONNECT,
 205        BPF_CGROUP_INET6_CONNECT,
 206        BPF_CGROUP_INET4_POST_BIND,
 207        BPF_CGROUP_INET6_POST_BIND,
 208        BPF_CGROUP_UDP4_SENDMSG,
 209        BPF_CGROUP_UDP6_SENDMSG,
 210        BPF_LIRC_MODE2,
 211#ifndef __GENKSYMS__
 212        BPF_FLOW_DISSECTOR,
 213        BPF_CGROUP_SYSCTL,
 214        BPF_CGROUP_UDP4_RECVMSG,
 215        BPF_CGROUP_UDP6_RECVMSG,
 216        BPF_CGROUP_GETSOCKOPT,
 217        BPF_CGROUP_SETSOCKOPT,
 218        BPF_TRACE_RAW_TP,
 219        BPF_TRACE_FENTRY,
 220        BPF_TRACE_FEXIT,
 221        BPF_MODIFY_RETURN,
 222        BPF_LSM_MAC,
 223#endif /* __GENKSYMS__ */
 224        __MAX_BPF_ATTACH_TYPE
 225};
 226
 227#define MAX_BPF_ATTACH_TYPE __MAX_BPF_ATTACH_TYPE
 228
 229/* cgroup-bpf attach flags used in BPF_PROG_ATTACH command
 230 *
 231 * NONE(default): No further bpf programs allowed in the subtree.
 232 *
 233 * BPF_F_ALLOW_OVERRIDE: If a sub-cgroup installs some bpf program,
 234 * the program in this cgroup yields to sub-cgroup program.
 235 *
 236 * BPF_F_ALLOW_MULTI: If a sub-cgroup installs some bpf program,
 237 * that cgroup program gets run in addition to the program in this cgroup.
 238 *
 239 * Only one program is allowed to be attached to a cgroup with
 240 * NONE or BPF_F_ALLOW_OVERRIDE flag.
 241 * Attaching another program on top of NONE or BPF_F_ALLOW_OVERRIDE will
 242 * release old program and attach the new one. Attach flags has to match.
 243 *
 244 * Multiple programs are allowed to be attached to a cgroup with
 245 * BPF_F_ALLOW_MULTI flag. They are executed in FIFO order
 246 * (those that were attached first, run first)
 247 * The programs of sub-cgroup are executed first, then programs of
 248 * this cgroup and then programs of parent cgroup.
 249 * When children program makes decision (like picking TCP CA or sock bind)
 250 * parent program has a chance to override it.
 251 *
 252 * With BPF_F_ALLOW_MULTI a new program is added to the end of the list of
 253 * programs for a cgroup. Though it's possible to replace an old program at
 254 * any position by also specifying BPF_F_REPLACE flag and position itself in
 255 * replace_bpf_fd attribute. Old program at this position will be released.
 256 *
 257 * A cgroup with MULTI or OVERRIDE flag allows any attach flags in sub-cgroups.
 258 * A cgroup with NONE doesn't allow any programs in sub-cgroups.
 259 * Ex1:
 260 * cgrp1 (MULTI progs A, B) ->
 261 *    cgrp2 (OVERRIDE prog C) ->
 262 *      cgrp3 (MULTI prog D) ->
 263 *        cgrp4 (OVERRIDE prog E) ->
 264 *          cgrp5 (NONE prog F)
 265 * the event in cgrp5 triggers execution of F,D,A,B in that order.
 266 * if prog F is detached, the execution is E,D,A,B
 267 * if prog F and D are detached, the execution is E,A,B
 268 * if prog F, E and D are detached, the execution is C,A,B
 269 *
 270 * All eligible programs are executed regardless of return code from
 271 * earlier programs.
 272 */
 273#define BPF_F_ALLOW_OVERRIDE    (1U << 0)
 274#define BPF_F_ALLOW_MULTI       (1U << 1)
 275#define BPF_F_REPLACE           (1U << 2)
 276
 277/* If BPF_F_STRICT_ALIGNMENT is used in BPF_PROG_LOAD command, the
 278 * verifier will perform strict alignment checking as if the kernel
 279 * has been built with CONFIG_EFFICIENT_UNALIGNED_ACCESS not set,
 280 * and NET_IP_ALIGN defined to 2.
 281 */
 282#define BPF_F_STRICT_ALIGNMENT  (1U << 0)
 283
 284/* If BPF_F_ANY_ALIGNMENT is used in BPF_PROF_LOAD command, the
 285 * verifier will allow any alignment whatsoever.  On platforms
 286 * with strict alignment requirements for loads ands stores (such
 287 * as sparc and mips) the verifier validates that all loads and
 288 * stores provably follow this requirement.  This flag turns that
 289 * checking and enforcement off.
 290 *
 291 * It is mostly used for testing when we want to validate the
 292 * context and memory access aspects of the verifier, but because
 293 * of an unaligned access the alignment check would trigger before
 294 * the one we are interested in.
 295 */
 296#define BPF_F_ANY_ALIGNMENT     (1U << 1)
 297
 298/* BPF_F_TEST_RND_HI32 is used in BPF_PROG_LOAD command for testing purpose.
 299 * Verifier does sub-register def/use analysis and identifies instructions whose
 300 * def only matters for low 32-bit, high 32-bit is never referenced later
 301 * through implicit zero extension. Therefore verifier notifies JIT back-ends
 302 * that it is safe to ignore clearing high 32-bit for these instructions. This
 303 * saves some back-ends a lot of code-gen. However such optimization is not
 304 * necessary on some arches, for example x86_64, arm64 etc, whose JIT back-ends
 305 * hence hasn't used verifier's analysis result. But, we really want to have a
 306 * way to be able to verify the correctness of the described optimization on
 307 * x86_64 on which testsuites are frequently exercised.
 308 *
 309 * So, this flag is introduced. Once it is set, verifier will randomize high
 310 * 32-bit for those instructions who has been identified as safe to ignore them.
 311 * Then, if verifier is not doing correct analysis, such randomization will
 312 * regress tests to expose bugs.
 313 */
 314#define BPF_F_TEST_RND_HI32     (1U << 2)
 315
 316/* The verifier internal test flag. Behavior is undefined */
 317#define BPF_F_TEST_STATE_FREQ   (1U << 3)
 318
 319/* When BPF ldimm64's insn[0].src_reg != 0 then this can have
 320 * two extensions:
 321 *
 322 * insn[0].src_reg:  BPF_PSEUDO_MAP_FD   BPF_PSEUDO_MAP_VALUE
 323 * insn[0].imm:      map fd              map fd
 324 * insn[1].imm:      0                   offset into value
 325 * insn[0].off:      0                   0
 326 * insn[1].off:      0                   0
 327 * ldimm64 rewrite:  address of map      address of map[0]+offset
 328 * verifier type:    CONST_PTR_TO_MAP    PTR_TO_MAP_VALUE
 329 */
 330#define BPF_PSEUDO_MAP_FD       1
 331#define BPF_PSEUDO_MAP_VALUE    2
 332
 333/* when bpf_call->src_reg == BPF_PSEUDO_CALL, bpf_call->imm == pc-relative
 334 * offset to another bpf function
 335 */
 336#define BPF_PSEUDO_CALL         1
 337
 338/* flags for BPF_MAP_UPDATE_ELEM command */
 339enum {
 340        BPF_ANY         = 0, /* create new element or update existing */
 341        BPF_NOEXIST     = 1, /* create new element if it didn't exist */
 342        BPF_EXIST       = 2, /* update existing element */
 343        BPF_F_LOCK      = 4, /* spin_lock-ed map_lookup/map_update */
 344};
 345
 346/* flags for BPF_MAP_CREATE command */
 347enum {
 348        BPF_F_NO_PREALLOC       = (1U << 0),
 349/* Instead of having one common LRU list in the
 350 * BPF_MAP_TYPE_LRU_[PERCPU_]HASH map, use a percpu LRU list
 351 * which can scale and perform better.
 352 * Note, the LRU nodes (including free nodes) cannot be moved
 353 * across different LRU lists.
 354 */
 355        BPF_F_NO_COMMON_LRU     = (1U << 1),
 356/* Specify numa node during map creation */
 357        BPF_F_NUMA_NODE         = (1U << 2),
 358
 359/* Flags for accessing BPF object from syscall side. */
 360        BPF_F_RDONLY            = (1U << 3),
 361        BPF_F_WRONLY            = (1U << 4),
 362
 363/* Flag for stack_map, store build_id+offset instead of pointer */
 364        BPF_F_STACK_BUILD_ID    = (1U << 5),
 365
 366/* Zero-initialize hash function seed. This should only be used for testing. */
 367        BPF_F_ZERO_SEED         = (1U << 6),
 368
 369/* Flags for accessing BPF object from program side. */
 370        BPF_F_RDONLY_PROG       = (1U << 7),
 371        BPF_F_WRONLY_PROG       = (1U << 8),
 372
 373/* Clone map from listener for newly accepted socket */
 374        BPF_F_CLONE             = (1U << 9),
 375
 376/* Enable memory-mapping BPF map */
 377        BPF_F_MMAPABLE          = (1U << 10),
 378};
 379
 380/* Flags for BPF_PROG_QUERY. */
 381
 382/* Query effective (directly attached + inherited from ancestor cgroups)
 383 * programs that will be executed for events within a cgroup.
 384 * attach_flags with this flag are returned only for directly attached programs.
 385 */
 386#define BPF_F_QUERY_EFFECTIVE   (1U << 0)
 387
 388enum bpf_stack_build_id_status {
 389        /* user space need an empty entry to identify end of a trace */
 390        BPF_STACK_BUILD_ID_EMPTY = 0,
 391        /* with valid build_id and offset */
 392        BPF_STACK_BUILD_ID_VALID = 1,
 393        /* couldn't get build_id, fallback to ip */
 394        BPF_STACK_BUILD_ID_IP = 2,
 395};
 396
 397#define BPF_BUILD_ID_SIZE 20
 398struct bpf_stack_build_id {
 399        __s32           status;
 400        unsigned char   build_id[BPF_BUILD_ID_SIZE];
 401        union {
 402                __u64   offset;
 403                __u64   ip;
 404        };
 405};
 406
 407#define BPF_OBJ_NAME_LEN 16U
 408
 409union bpf_attr {
 410        struct { /* anonymous struct used by BPF_MAP_CREATE command */
 411                __u32   map_type;       /* one of enum bpf_map_type */
 412                __u32   key_size;       /* size of key in bytes */
 413                __u32   value_size;     /* size of value in bytes */
 414                __u32   max_entries;    /* max number of entries in a map */
 415                __u32   map_flags;      /* BPF_MAP_CREATE related
 416                                         * flags defined above.
 417                                         */
 418                __u32   inner_map_fd;   /* fd pointing to the inner map */
 419                __u32   numa_node;      /* numa node (effective only if
 420                                         * BPF_F_NUMA_NODE is set).
 421                                         */
 422                char    map_name[BPF_OBJ_NAME_LEN];
 423                __u32   map_ifindex;    /* ifindex of netdev to create on */
 424                __u32   btf_fd;         /* fd pointing to a BTF type data */
 425                __u32   btf_key_type_id;        /* BTF type_id of the key */
 426                __u32   btf_value_type_id;      /* BTF type_id of the value */
 427#ifndef __GENKSYMS__
 428                __u32   btf_vmlinux_value_type_id;/* BTF type_id of a kernel-
 429                                                   * struct stored as the
 430                                                   * map value
 431                                                   */
 432#endif /* __GENKSYMS__ */
 433        };
 434
 435        struct { /* anonymous struct used by BPF_MAP_*_ELEM commands */
 436                __u32           map_fd;
 437                __aligned_u64   key;
 438                union {
 439                        __aligned_u64 value;
 440                        __aligned_u64 next_key;
 441                };
 442                __u64           flags;
 443        };
 444
 445#ifndef __GENKSYMS__
 446        struct { /* struct used by BPF_MAP_*_BATCH commands */
 447                __aligned_u64   in_batch;       /* start batch,
 448                                                 * NULL to start from beginning
 449                                                 */
 450                __aligned_u64   out_batch;      /* output: next start batch */
 451                __aligned_u64   keys;
 452                __aligned_u64   values;
 453                __u32           count;          /* input/output:
 454                                                 * input: # of key/value
 455                                                 * elements
 456                                                 * output: # of filled elements
 457                                                 */
 458                __u32           map_fd;
 459                __u64           elem_flags;
 460                __u64           flags;
 461        } batch;
 462#endif /* __GENKSYMS__ */
 463
 464        struct { /* anonymous struct used by BPF_PROG_LOAD command */
 465                __u32           prog_type;      /* one of enum bpf_prog_type */
 466                __u32           insn_cnt;
 467                __aligned_u64   insns;
 468                __aligned_u64   license;
 469                __u32           log_level;      /* verbosity level of verifier */
 470                __u32           log_size;       /* size of user buffer */
 471                __aligned_u64   log_buf;        /* user supplied buffer */
 472                __u32           kern_version;   /* not used */
 473                __u32           prog_flags;
 474                char            prog_name[BPF_OBJ_NAME_LEN];
 475                __u32           prog_ifindex;   /* ifindex of netdev to prep for */
 476                /* For some prog types expected attach type must be known at
 477                 * load time to verify attach type specific parts of prog
 478                 * (context accesses, allowed helpers, etc).
 479                 */
 480                __u32           expected_attach_type;
 481#ifndef __GENKSYMS__
 482                __u32           prog_btf_fd;    /* fd pointing to BTF type data */
 483                __u32           func_info_rec_size;     /* userspace bpf_func_info size */
 484                __aligned_u64   func_info;      /* func info */
 485                __u32           func_info_cnt;  /* number of bpf_func_info records */
 486                __u32           line_info_rec_size;     /* userspace bpf_line_info size */
 487                __aligned_u64   line_info;      /* line info */
 488                __u32           line_info_cnt;  /* number of bpf_line_info records */
 489                __u32           attach_btf_id;  /* in-kernel BTF type id to attach to */
 490                __u32           attach_prog_fd; /* 0 to attach to vmlinux */
 491#endif /* __GENKSYMS__ */
 492        };
 493
 494        struct { /* anonymous struct used by BPF_OBJ_* commands */
 495                __aligned_u64   pathname;
 496                __u32           bpf_fd;
 497                __u32           file_flags;
 498        };
 499
 500        struct { /* anonymous struct used by BPF_PROG_ATTACH/DETACH commands */
 501                __u32           target_fd;      /* container object to attach to */
 502                __u32           attach_bpf_fd;  /* eBPF program to attach */
 503                __u32           attach_type;
 504                __u32           attach_flags;
 505#ifndef __GENKSYMS__
 506                __u32           replace_bpf_fd; /* previously attached eBPF
 507                                                 * program to replace if
 508                                                 * BPF_F_REPLACE is used
 509                                                 */
 510#endif /* __GENKSYMS__ */
 511        };
 512
 513        struct { /* anonymous struct used by BPF_PROG_TEST_RUN command */
 514                __u32           prog_fd;
 515                __u32           retval;
 516                __u32           data_size_in;   /* input: len of data_in */
 517                __u32           data_size_out;  /* input/output: len of data_out
 518                                                 *   returns ENOSPC if data_out
 519                                                 *   is too small.
 520                                                 */
 521                __aligned_u64   data_in;
 522                __aligned_u64   data_out;
 523                __u32           repeat;
 524                __u32           duration;
 525#ifndef __GENKSYMS__
 526                __u32           ctx_size_in;    /* input: len of ctx_in */
 527                __u32           ctx_size_out;   /* input/output: len of ctx_out
 528                                                 *   returns ENOSPC if ctx_out
 529                                                 *   is too small.
 530                                                 */
 531                __aligned_u64   ctx_in;
 532                __aligned_u64   ctx_out;
 533#endif /* __GENKSYMS__ */
 534        } test;
 535
 536        struct { /* anonymous struct used by BPF_*_GET_*_ID */
 537                union {
 538                        __u32           start_id;
 539                        __u32           prog_id;
 540                        __u32           map_id;
 541                        __u32           btf_id;
 542                };
 543                __u32           next_id;
 544                __u32           open_flags;
 545        };
 546
 547        struct { /* anonymous struct used by BPF_OBJ_GET_INFO_BY_FD */
 548                __u32           bpf_fd;
 549                __u32           info_len;
 550                __aligned_u64   info;
 551        } info;
 552
 553        struct { /* anonymous struct used by BPF_PROG_QUERY command */
 554                __u32           target_fd;      /* container object to query */
 555                __u32           attach_type;
 556                __u32           query_flags;
 557                __u32           attach_flags;
 558                __aligned_u64   prog_ids;
 559                __u32           prog_cnt;
 560        } query;
 561
 562        struct { /* anonymous struct used by BPF_RAW_TRACEPOINT_OPEN command */
 563                __u64 name;
 564                __u32 prog_fd;
 565        } raw_tracepoint;
 566
 567        struct { /* anonymous struct for BPF_BTF_LOAD */
 568                __aligned_u64   btf;
 569                __aligned_u64   btf_log_buf;
 570                __u32           btf_size;
 571                __u32           btf_log_size;
 572                __u32           btf_log_level;
 573        };
 574
 575        struct {
 576                __u32           pid;            /* input: pid */
 577                __u32           fd;             /* input: fd */
 578                __u32           flags;          /* input: flags */
 579                __u32           buf_len;        /* input/output: buf len */
 580                __aligned_u64   buf;            /* input/output:
 581                                                 *   tp_name for tracepoint
 582                                                 *   symbol for kprobe
 583                                                 *   filename for uprobe
 584                                                 */
 585                __u32           prog_id;        /* output: prod_id */
 586                __u32           fd_type;        /* output: BPF_FD_TYPE_* */
 587                __u64           probe_offset;   /* output: probe_offset */
 588                __u64           probe_addr;     /* output: probe_addr */
 589        } task_fd_query;
 590#ifndef __GENKSYMS__
 591
 592        struct { /* struct used by BPF_LINK_CREATE command */
 593                __u32           prog_fd;        /* eBPF program to attach */
 594                __u32           target_fd;      /* object to attach to */
 595                __u32           attach_type;    /* attach type */
 596                __u32           flags;          /* extra flags */
 597        } link_create;
 598
 599        struct { /* struct used by BPF_LINK_UPDATE command */
 600                __u32           link_fd;        /* link fd */
 601                /* new program fd to update link with */
 602                __u32           new_prog_fd;
 603                __u32           flags;          /* extra flags */
 604                /* expected link's program fd; is specified only if
 605                 * BPF_F_REPLACE flag is set in flags */
 606                __u32           old_prog_fd;
 607        } link_update;
 608
 609#endif /* __GENKSYMS__ */
 610} __attribute__((aligned(8)));
 611
 612/* The description below is an attempt at providing documentation to eBPF
 613 * developers about the multiple available eBPF helper functions. It can be
 614 * parsed and used to produce a manual page. The workflow is the following,
 615 * and requires the rst2man utility:
 616 *
 617 *     $ ./scripts/bpf_helpers_doc.py \
 618 *             --filename include/uapi/linux/bpf.h > /tmp/bpf-helpers.rst
 619 *     $ rst2man /tmp/bpf-helpers.rst > /tmp/bpf-helpers.7
 620 *     $ man /tmp/bpf-helpers.7
 621 *
 622 * Note that in order to produce this external documentation, some RST
 623 * formatting is used in the descriptions to get "bold" and "italics" in
 624 * manual pages. Also note that the few trailing white spaces are
 625 * intentional, removing them would break paragraphs for rst2man.
 626 *
 627 * Start of BPF helper function descriptions:
 628 *
 629 * void *bpf_map_lookup_elem(struct bpf_map *map, const void *key)
 630 *      Description
 631 *              Perform a lookup in *map* for an entry associated to *key*.
 632 *      Return
 633 *              Map value associated to *key*, or **NULL** if no entry was
 634 *              found.
 635 *
 636 * int bpf_map_update_elem(struct bpf_map *map, const void *key, const void *value, u64 flags)
 637 *      Description
 638 *              Add or update the value of the entry associated to *key* in
 639 *              *map* with *value*. *flags* is one of:
 640 *
 641 *              **BPF_NOEXIST**
 642 *                      The entry for *key* must not exist in the map.
 643 *              **BPF_EXIST**
 644 *                      The entry for *key* must already exist in the map.
 645 *              **BPF_ANY**
 646 *                      No condition on the existence of the entry for *key*.
 647 *
 648 *              Flag value **BPF_NOEXIST** cannot be used for maps of types
 649 *              **BPF_MAP_TYPE_ARRAY** or **BPF_MAP_TYPE_PERCPU_ARRAY**  (all
 650 *              elements always exist), the helper would return an error.
 651 *      Return
 652 *              0 on success, or a negative error in case of failure.
 653 *
 654 * int bpf_map_delete_elem(struct bpf_map *map, const void *key)
 655 *      Description
 656 *              Delete entry with *key* from *map*.
 657 *      Return
 658 *              0 on success, or a negative error in case of failure.
 659 *
 660 * int bpf_probe_read(void *dst, u32 size, const void *unsafe_ptr)
 661 *      Description
 662 *              For tracing programs, safely attempt to read *size* bytes from
 663 *              kernel space address *unsafe_ptr* and store the data in *dst*.
 664 *
 665 *              Generally, use bpf_probe_read_user() or bpf_probe_read_kernel()
 666 *              instead.
 667 *      Return
 668 *              0 on success, or a negative error in case of failure.
 669 *
 670 * u64 bpf_ktime_get_ns(void)
 671 *      Description
 672 *              Return the time elapsed since system boot, in nanoseconds.
 673 *      Return
 674 *              Current *ktime*.
 675 *
 676 * int bpf_trace_printk(const char *fmt, u32 fmt_size, ...)
 677 *      Description
 678 *              This helper is a "printk()-like" facility for debugging. It
 679 *              prints a message defined by format *fmt* (of size *fmt_size*)
 680 *              to file *\/sys/kernel/debug/tracing/trace* from DebugFS, if
 681 *              available. It can take up to three additional **u64**
 682 *              arguments (as an eBPF helpers, the total number of arguments is
 683 *              limited to five).
 684 *
 685 *              Each time the helper is called, it appends a line to the trace.
 686 *              Lines are discarded while *\/sys/kernel/debug/tracing/trace* is
 687 *              open, use *\/sys/kernel/debug/tracing/trace_pipe* to avoid this.
 688 *              The format of the trace is customizable, and the exact output
 689 *              one will get depends on the options set in
 690 *              *\/sys/kernel/debug/tracing/trace_options* (see also the
 691 *              *README* file under the same directory). However, it usually
 692 *              defaults to something like:
 693 *
 694 *              ::
 695 *
 696 *                      telnet-470   [001] .N.. 419421.045894: 0x00000001: <formatted msg>
 697 *
 698 *              In the above:
 699 *
 700 *                      * ``telnet`` is the name of the current task.
 701 *                      * ``470`` is the PID of the current task.
 702 *                      * ``001`` is the CPU number on which the task is
 703 *                        running.
 704 *                      * In ``.N..``, each character refers to a set of
 705 *                        options (whether irqs are enabled, scheduling
 706 *                        options, whether hard/softirqs are running, level of
 707 *                        preempt_disabled respectively). **N** means that
 708 *                        **TIF_NEED_RESCHED** and **PREEMPT_NEED_RESCHED**
 709 *                        are set.
 710 *                      * ``419421.045894`` is a timestamp.
 711 *                      * ``0x00000001`` is a fake value used by BPF for the
 712 *                        instruction pointer register.
 713 *                      * ``<formatted msg>`` is the message formatted with
 714 *                        *fmt*.
 715 *
 716 *              The conversion specifiers supported by *fmt* are similar, but
 717 *              more limited than for printk(). They are **%d**, **%i**,
 718 *              **%u**, **%x**, **%ld**, **%li**, **%lu**, **%lx**, **%lld**,
 719 *              **%lli**, **%llu**, **%llx**, **%p**, **%s**. No modifier (size
 720 *              of field, padding with zeroes, etc.) is available, and the
 721 *              helper will return **-EINVAL** (but print nothing) if it
 722 *              encounters an unknown specifier.
 723 *
 724 *              Also, note that **bpf_trace_printk**\ () is slow, and should
 725 *              only be used for debugging purposes. For this reason, a notice
 726 *              bloc (spanning several lines) is printed to kernel logs and
 727 *              states that the helper should not be used "for production use"
 728 *              the first time this helper is used (or more precisely, when
 729 *              **trace_printk**\ () buffers are allocated). For passing values
 730 *              to user space, perf events should be preferred.
 731 *      Return
 732 *              The number of bytes written to the buffer, or a negative error
 733 *              in case of failure.
 734 *
 735 * u32 bpf_get_prandom_u32(void)
 736 *      Description
 737 *              Get a pseudo-random number.
 738 *
 739 *              From a security point of view, this helper uses its own
 740 *              pseudo-random internal state, and cannot be used to infer the
 741 *              seed of other random functions in the kernel. However, it is
 742 *              essential to note that the generator used by the helper is not
 743 *              cryptographically secure.
 744 *      Return
 745 *              A random 32-bit unsigned value.
 746 *
 747 * u32 bpf_get_smp_processor_id(void)
 748 *      Description
 749 *              Get the SMP (symmetric multiprocessing) processor id. Note that
 750 *              all programs run with preemption disabled, which means that the
 751 *              SMP processor id is stable during all the execution of the
 752 *              program.
 753 *      Return
 754 *              The SMP id of the processor running the program.
 755 *
 756 * int bpf_skb_store_bytes(struct sk_buff *skb, u32 offset, const void *from, u32 len, u64 flags)
 757 *      Description
 758 *              Store *len* bytes from address *from* into the packet
 759 *              associated to *skb*, at *offset*. *flags* are a combination of
 760 *              **BPF_F_RECOMPUTE_CSUM** (automatically recompute the
 761 *              checksum for the packet after storing the bytes) and
 762 *              **BPF_F_INVALIDATE_HASH** (set *skb*\ **->hash**, *skb*\
 763 *              **->swhash** and *skb*\ **->l4hash** to 0).
 764 *
 765 *              A call to this helper is susceptible to change the underlying
 766 *              packet buffer. Therefore, at load time, all checks on pointers
 767 *              previously done by the verifier are invalidated and must be
 768 *              performed again, if the helper is used in combination with
 769 *              direct packet access.
 770 *      Return
 771 *              0 on success, or a negative error in case of failure.
 772 *
 773 * int bpf_l3_csum_replace(struct sk_buff *skb, u32 offset, u64 from, u64 to, u64 size)
 774 *      Description
 775 *              Recompute the layer 3 (e.g. IP) checksum for the packet
 776 *              associated to *skb*. Computation is incremental, so the helper
 777 *              must know the former value of the header field that was
 778 *              modified (*from*), the new value of this field (*to*), and the
 779 *              number of bytes (2 or 4) for this field, stored in *size*.
 780 *              Alternatively, it is possible to store the difference between
 781 *              the previous and the new values of the header field in *to*, by
 782 *              setting *from* and *size* to 0. For both methods, *offset*
 783 *              indicates the location of the IP checksum within the packet.
 784 *
 785 *              This helper works in combination with **bpf_csum_diff**\ (),
 786 *              which does not update the checksum in-place, but offers more
 787 *              flexibility and can handle sizes larger than 2 or 4 for the
 788 *              checksum to update.
 789 *
 790 *              A call to this helper is susceptible to change the underlying
 791 *              packet buffer. Therefore, at load time, all checks on pointers
 792 *              previously done by the verifier are invalidated and must be
 793 *              performed again, if the helper is used in combination with
 794 *              direct packet access.
 795 *      Return
 796 *              0 on success, or a negative error in case of failure.
 797 *
 798 * int bpf_l4_csum_replace(struct sk_buff *skb, u32 offset, u64 from, u64 to, u64 flags)
 799 *      Description
 800 *              Recompute the layer 4 (e.g. TCP, UDP or ICMP) checksum for the
 801 *              packet associated to *skb*. Computation is incremental, so the
 802 *              helper must know the former value of the header field that was
 803 *              modified (*from*), the new value of this field (*to*), and the
 804 *              number of bytes (2 or 4) for this field, stored on the lowest
 805 *              four bits of *flags*. Alternatively, it is possible to store
 806 *              the difference between the previous and the new values of the
 807 *              header field in *to*, by setting *from* and the four lowest
 808 *              bits of *flags* to 0. For both methods, *offset* indicates the
 809 *              location of the IP checksum within the packet. In addition to
 810 *              the size of the field, *flags* can be added (bitwise OR) actual
 811 *              flags. With **BPF_F_MARK_MANGLED_0**, a null checksum is left
 812 *              untouched (unless **BPF_F_MARK_ENFORCE** is added as well), and
 813 *              for updates resulting in a null checksum the value is set to
 814 *              **CSUM_MANGLED_0** instead. Flag **BPF_F_PSEUDO_HDR** indicates
 815 *              the checksum is to be computed against a pseudo-header.
 816 *
 817 *              This helper works in combination with **bpf_csum_diff**\ (),
 818 *              which does not update the checksum in-place, but offers more
 819 *              flexibility and can handle sizes larger than 2 or 4 for the
 820 *              checksum to update.
 821 *
 822 *              A call to this helper is susceptible to change the underlying
 823 *              packet buffer. Therefore, at load time, all checks on pointers
 824 *              previously done by the verifier are invalidated and must be
 825 *              performed again, if the helper is used in combination with
 826 *              direct packet access.
 827 *      Return
 828 *              0 on success, or a negative error in case of failure.
 829 *
 830 * int bpf_tail_call(void *ctx, struct bpf_map *prog_array_map, u32 index)
 831 *      Description
 832 *              This special helper is used to trigger a "tail call", or in
 833 *              other words, to jump into another eBPF program. The same stack
 834 *              frame is used (but values on stack and in registers for the
 835 *              caller are not accessible to the callee). This mechanism allows
 836 *              for program chaining, either for raising the maximum number of
 837 *              available eBPF instructions, or to execute given programs in
 838 *              conditional blocks. For security reasons, there is an upper
 839 *              limit to the number of successive tail calls that can be
 840 *              performed.
 841 *
 842 *              Upon call of this helper, the program attempts to jump into a
 843 *              program referenced at index *index* in *prog_array_map*, a
 844 *              special map of type **BPF_MAP_TYPE_PROG_ARRAY**, and passes
 845 *              *ctx*, a pointer to the context.
 846 *
 847 *              If the call succeeds, the kernel immediately runs the first
 848 *              instruction of the new program. This is not a function call,
 849 *              and it never returns to the previous program. If the call
 850 *              fails, then the helper has no effect, and the caller continues
 851 *              to run its subsequent instructions. A call can fail if the
 852 *              destination program for the jump does not exist (i.e. *index*
 853 *              is superior to the number of entries in *prog_array_map*), or
 854 *              if the maximum number of tail calls has been reached for this
 855 *              chain of programs. This limit is defined in the kernel by the
 856 *              macro **MAX_TAIL_CALL_CNT** (not accessible to user space),
 857 *              which is currently set to 32.
 858 *      Return
 859 *              0 on success, or a negative error in case of failure.
 860 *
 861 * int bpf_clone_redirect(struct sk_buff *skb, u32 ifindex, u64 flags)
 862 *      Description
 863 *              Clone and redirect the packet associated to *skb* to another
 864 *              net device of index *ifindex*. Both ingress and egress
 865 *              interfaces can be used for redirection. The **BPF_F_INGRESS**
 866 *              value in *flags* is used to make the distinction (ingress path
 867 *              is selected if the flag is present, egress path otherwise).
 868 *              This is the only flag supported for now.
 869 *
 870 *              In comparison with **bpf_redirect**\ () helper,
 871 *              **bpf_clone_redirect**\ () has the associated cost of
 872 *              duplicating the packet buffer, but this can be executed out of
 873 *              the eBPF program. Conversely, **bpf_redirect**\ () is more
 874 *              efficient, but it is handled through an action code where the
 875 *              redirection happens only after the eBPF program has returned.
 876 *
 877 *              A call to this helper is susceptible to change the underlying
 878 *              packet buffer. Therefore, at load time, all checks on pointers
 879 *              previously done by the verifier are invalidated and must be
 880 *              performed again, if the helper is used in combination with
 881 *              direct packet access.
 882 *      Return
 883 *              0 on success, or a negative error in case of failure.
 884 *
 885 * u64 bpf_get_current_pid_tgid(void)
 886 *      Return
 887 *              A 64-bit integer containing the current tgid and pid, and
 888 *              created as such:
 889 *              *current_task*\ **->tgid << 32 \|**
 890 *              *current_task*\ **->pid**.
 891 *
 892 * u64 bpf_get_current_uid_gid(void)
 893 *      Return
 894 *              A 64-bit integer containing the current GID and UID, and
 895 *              created as such: *current_gid* **<< 32 \|** *current_uid*.
 896 *
 897 * int bpf_get_current_comm(void *buf, u32 size_of_buf)
 898 *      Description
 899 *              Copy the **comm** attribute of the current task into *buf* of
 900 *              *size_of_buf*. The **comm** attribute contains the name of
 901 *              the executable (excluding the path) for the current task. The
 902 *              *size_of_buf* must be strictly positive. On success, the
 903 *              helper makes sure that the *buf* is NUL-terminated. On failure,
 904 *              it is filled with zeroes.
 905 *      Return
 906 *              0 on success, or a negative error in case of failure.
 907 *
 908 * u32 bpf_get_cgroup_classid(struct sk_buff *skb)
 909 *      Description
 910 *              Retrieve the classid for the current task, i.e. for the net_cls
 911 *              cgroup to which *skb* belongs.
 912 *
 913 *              This helper can be used on TC egress path, but not on ingress.
 914 *
 915 *              The net_cls cgroup provides an interface to tag network packets
 916 *              based on a user-provided identifier for all traffic coming from
 917 *              the tasks belonging to the related cgroup. See also the related
 918 *              kernel documentation, available from the Linux sources in file
 919 *              *Documentation/cgroup-v1/net_cls.txt*.
 920 *
 921 *              The Linux kernel has two versions for cgroups: there are
 922 *              cgroups v1 and cgroups v2. Both are available to users, who can
 923 *              use a mixture of them, but note that the net_cls cgroup is for
 924 *              cgroup v1 only. This makes it incompatible with BPF programs
 925 *              run on cgroups, which is a cgroup-v2-only feature (a socket can
 926 *              only hold data for one version of cgroups at a time).
 927 *
 928 *              This helper is only available is the kernel was compiled with
 929 *              the **CONFIG_CGROUP_NET_CLASSID** configuration option set to
 930 *              "**y**" or to "**m**".
 931 *      Return
 932 *              The classid, or 0 for the default unconfigured classid.
 933 *
 934 * int bpf_skb_vlan_push(struct sk_buff *skb, __be16 vlan_proto, u16 vlan_tci)
 935 *      Description
 936 *              Push a *vlan_tci* (VLAN tag control information) of protocol
 937 *              *vlan_proto* to the packet associated to *skb*, then update
 938 *              the checksum. Note that if *vlan_proto* is different from
 939 *              **ETH_P_8021Q** and **ETH_P_8021AD**, it is considered to
 940 *              be **ETH_P_8021Q**.
 941 *
 942 *              A call to this helper is susceptible to change the underlying
 943 *              packet buffer. Therefore, at load time, all checks on pointers
 944 *              previously done by the verifier are invalidated and must be
 945 *              performed again, if the helper is used in combination with
 946 *              direct packet access.
 947 *      Return
 948 *              0 on success, or a negative error in case of failure.
 949 *
 950 * int bpf_skb_vlan_pop(struct sk_buff *skb)
 951 *      Description
 952 *              Pop a VLAN header from the packet associated to *skb*.
 953 *
 954 *              A call to this helper is susceptible to change the underlying
 955 *              packet buffer. Therefore, at load time, all checks on pointers
 956 *              previously done by the verifier are invalidated and must be
 957 *              performed again, if the helper is used in combination with
 958 *              direct packet access.
 959 *      Return
 960 *              0 on success, or a negative error in case of failure.
 961 *
 962 * int bpf_skb_get_tunnel_key(struct sk_buff *skb, struct bpf_tunnel_key *key, u32 size, u64 flags)
 963 *      Description
 964 *              Get tunnel metadata. This helper takes a pointer *key* to an
 965 *              empty **struct bpf_tunnel_key** of **size**, that will be
 966 *              filled with tunnel metadata for the packet associated to *skb*.
 967 *              The *flags* can be set to **BPF_F_TUNINFO_IPV6**, which
 968 *              indicates that the tunnel is based on IPv6 protocol instead of
 969 *              IPv4.
 970 *
 971 *              The **struct bpf_tunnel_key** is an object that generalizes the
 972 *              principal parameters used by various tunneling protocols into a
 973 *              single struct. This way, it can be used to easily make a
 974 *              decision based on the contents of the encapsulation header,
 975 *              "summarized" in this struct. In particular, it holds the IP
 976 *              address of the remote end (IPv4 or IPv6, depending on the case)
 977 *              in *key*\ **->remote_ipv4** or *key*\ **->remote_ipv6**. Also,
 978 *              this struct exposes the *key*\ **->tunnel_id**, which is
 979 *              generally mapped to a VNI (Virtual Network Identifier), making
 980 *              it programmable together with the **bpf_skb_set_tunnel_key**\
 981 *              () helper.
 982 *
 983 *              Let's imagine that the following code is part of a program
 984 *              attached to the TC ingress interface, on one end of a GRE
 985 *              tunnel, and is supposed to filter out all messages coming from
 986 *              remote ends with IPv4 address other than 10.0.0.1:
 987 *
 988 *              ::
 989 *
 990 *                      int ret;
 991 *                      struct bpf_tunnel_key key = {};
 992 *                      
 993 *                      ret = bpf_skb_get_tunnel_key(skb, &key, sizeof(key), 0);
 994 *                      if (ret < 0)
 995 *                              return TC_ACT_SHOT;     // drop packet
 996 *                      
 997 *                      if (key.remote_ipv4 != 0x0a000001)
 998 *                              return TC_ACT_SHOT;     // drop packet
 999 *                      
1000 *                      return TC_ACT_OK;               // accept packet
1001 *
1002 *              This interface can also be used with all encapsulation devices
1003 *              that can operate in "collect metadata" mode: instead of having
1004 *              one network device per specific configuration, the "collect
1005 *              metadata" mode only requires a single device where the
1006 *              configuration can be extracted from this helper.
1007 *
1008 *              This can be used together with various tunnels such as VXLan,
1009 *              Geneve, GRE or IP in IP (IPIP).
1010 *      Return
1011 *              0 on success, or a negative error in case of failure.
1012 *
1013 * int bpf_skb_set_tunnel_key(struct sk_buff *skb, struct bpf_tunnel_key *key, u32 size, u64 flags)
1014 *      Description
1015 *              Populate tunnel metadata for packet associated to *skb.* The
1016 *              tunnel metadata is set to the contents of *key*, of *size*. The
1017 *              *flags* can be set to a combination of the following values:
1018 *
1019 *              **BPF_F_TUNINFO_IPV6**
1020 *                      Indicate that the tunnel is based on IPv6 protocol
1021 *                      instead of IPv4.
1022 *              **BPF_F_ZERO_CSUM_TX**
1023 *                      For IPv4 packets, add a flag to tunnel metadata
1024 *                      indicating that checksum computation should be skipped
1025 *                      and checksum set to zeroes.
1026 *              **BPF_F_DONT_FRAGMENT**
1027 *                      Add a flag to tunnel metadata indicating that the
1028 *                      packet should not be fragmented.
1029 *              **BPF_F_SEQ_NUMBER**
1030 *                      Add a flag to tunnel metadata indicating that a
1031 *                      sequence number should be added to tunnel header before
1032 *                      sending the packet. This flag was added for GRE
1033 *                      encapsulation, but might be used with other protocols
1034 *                      as well in the future.
1035 *
1036 *              Here is a typical usage on the transmit path:
1037 *
1038 *              ::
1039 *
1040 *                      struct bpf_tunnel_key key;
1041 *                           populate key ...
1042 *                      bpf_skb_set_tunnel_key(skb, &key, sizeof(key), 0);
1043 *                      bpf_clone_redirect(skb, vxlan_dev_ifindex, 0);
1044 *
1045 *              See also the description of the **bpf_skb_get_tunnel_key**\ ()
1046 *              helper for additional information.
1047 *      Return
1048 *              0 on success, or a negative error in case of failure.
1049 *
1050 * u64 bpf_perf_event_read(struct bpf_map *map, u64 flags)
1051 *      Description
1052 *              Read the value of a perf event counter. This helper relies on a
1053 *              *map* of type **BPF_MAP_TYPE_PERF_EVENT_ARRAY**. The nature of
1054 *              the perf event counter is selected when *map* is updated with
1055 *              perf event file descriptors. The *map* is an array whose size
1056 *              is the number of available CPUs, and each cell contains a value
1057 *              relative to one CPU. The value to retrieve is indicated by
1058 *              *flags*, that contains the index of the CPU to look up, masked
1059 *              with **BPF_F_INDEX_MASK**. Alternatively, *flags* can be set to
1060 *              **BPF_F_CURRENT_CPU** to indicate that the value for the
1061 *              current CPU should be retrieved.
1062 *
1063 *              Note that before Linux 4.13, only hardware perf event can be
1064 *              retrieved.
1065 *
1066 *              Also, be aware that the newer helper
1067 *              **bpf_perf_event_read_value**\ () is recommended over
1068 *              **bpf_perf_event_read**\ () in general. The latter has some ABI
1069 *              quirks where error and counter value are used as a return code
1070 *              (which is wrong to do since ranges may overlap). This issue is
1071 *              fixed with **bpf_perf_event_read_value**\ (), which at the same
1072 *              time provides more features over the **bpf_perf_event_read**\
1073 *              () interface. Please refer to the description of
1074 *              **bpf_perf_event_read_value**\ () for details.
1075 *      Return
1076 *              The value of the perf event counter read from the map, or a
1077 *              negative error code in case of failure.
1078 *
1079 * int bpf_redirect(u32 ifindex, u64 flags)
1080 *      Description
1081 *              Redirect the packet to another net device of index *ifindex*.
1082 *              This helper is somewhat similar to **bpf_clone_redirect**\
1083 *              (), except that the packet is not cloned, which provides
1084 *              increased performance.
1085 *
1086 *              Except for XDP, both ingress and egress interfaces can be used
1087 *              for redirection. The **BPF_F_INGRESS** value in *flags* is used
1088 *              to make the distinction (ingress path is selected if the flag
1089 *              is present, egress path otherwise). Currently, XDP only
1090 *              supports redirection to the egress interface, and accepts no
1091 *              flag at all.
1092 *
1093 *              The same effect can also be attained with the more generic
1094 *              **bpf_redirect_map**\ (), which uses a BPF map to store the
1095 *              redirect target instead of providing it directly to the helper.
1096 *      Return
1097 *              For XDP, the helper returns **XDP_REDIRECT** on success or
1098 *              **XDP_ABORTED** on error. For other program types, the values
1099 *              are **TC_ACT_REDIRECT** on success or **TC_ACT_SHOT** on
1100 *              error.
1101 *
1102 * u32 bpf_get_route_realm(struct sk_buff *skb)
1103 *      Description
1104 *              Retrieve the realm or the route, that is to say the
1105 *              **tclassid** field of the destination for the *skb*. The
1106 *              indentifier retrieved is a user-provided tag, similar to the
1107 *              one used with the net_cls cgroup (see description for
1108 *              **bpf_get_cgroup_classid**\ () helper), but here this tag is
1109 *              held by a route (a destination entry), not by a task.
1110 *
1111 *              Retrieving this identifier works with the clsact TC egress hook
1112 *              (see also **tc-bpf(8)**), or alternatively on conventional
1113 *              classful egress qdiscs, but not on TC ingress path. In case of
1114 *              clsact TC egress hook, this has the advantage that, internally,
1115 *              the destination entry has not been dropped yet in the transmit
1116 *              path. Therefore, the destination entry does not need to be
1117 *              artificially held via **netif_keep_dst**\ () for a classful
1118 *              qdisc until the *skb* is freed.
1119 *
1120 *              This helper is available only if the kernel was compiled with
1121 *              **CONFIG_IP_ROUTE_CLASSID** configuration option.
1122 *      Return
1123 *              The realm of the route for the packet associated to *skb*, or 0
1124 *              if none was found.
1125 *
1126 * int bpf_perf_event_output(void *ctx, struct bpf_map *map, u64 flags, void *data, u64 size)
1127 *      Description
1128 *              Write raw *data* blob into a special BPF perf event held by
1129 *              *map* of type **BPF_MAP_TYPE_PERF_EVENT_ARRAY**. This perf
1130 *              event must have the following attributes: **PERF_SAMPLE_RAW**
1131 *              as **sample_type**, **PERF_TYPE_SOFTWARE** as **type**, and
1132 *              **PERF_COUNT_SW_BPF_OUTPUT** as **config**.
1133 *
1134 *              The *flags* are used to indicate the index in *map* for which
1135 *              the value must be put, masked with **BPF_F_INDEX_MASK**.
1136 *              Alternatively, *flags* can be set to **BPF_F_CURRENT_CPU**
1137 *              to indicate that the index of the current CPU core should be
1138 *              used.
1139 *
1140 *              The value to write, of *size*, is passed through eBPF stack and
1141 *              pointed by *data*.
1142 *
1143 *              The context of the program *ctx* needs also be passed to the
1144 *              helper.
1145 *
1146 *              On user space, a program willing to read the values needs to
1147 *              call **perf_event_open**\ () on the perf event (either for
1148 *              one or for all CPUs) and to store the file descriptor into the
1149 *              *map*. This must be done before the eBPF program can send data
1150 *              into it. An example is available in file
1151 *              *samples/bpf/trace_output_user.c* in the Linux kernel source
1152 *              tree (the eBPF program counterpart is in
1153 *              *samples/bpf/trace_output_kern.c*).
1154 *
1155 *              **bpf_perf_event_output**\ () achieves better performance
1156 *              than **bpf_trace_printk**\ () for sharing data with user
1157 *              space, and is much better suitable for streaming data from eBPF
1158 *              programs.
1159 *
1160 *              Note that this helper is not restricted to tracing use cases
1161 *              and can be used with programs attached to TC or XDP as well,
1162 *              where it allows for passing data to user space listeners. Data
1163 *              can be:
1164 *
1165 *              * Only custom structs,
1166 *              * Only the packet payload, or
1167 *              * A combination of both.
1168 *      Return
1169 *              0 on success, or a negative error in case of failure.
1170 *
1171 * int bpf_skb_load_bytes(const void *skb, u32 offset, void *to, u32 len)
1172 *      Description
1173 *              This helper was provided as an easy way to load data from a
1174 *              packet. It can be used to load *len* bytes from *offset* from
1175 *              the packet associated to *skb*, into the buffer pointed by
1176 *              *to*.
1177 *
1178 *              Since Linux 4.7, usage of this helper has mostly been replaced
1179 *              by "direct packet access", enabling packet data to be
1180 *              manipulated with *skb*\ **->data** and *skb*\ **->data_end**
1181 *              pointing respectively to the first byte of packet data and to
1182 *              the byte after the last byte of packet data. However, it
1183 *              remains useful if one wishes to read large quantities of data
1184 *              at once from a packet into the eBPF stack.
1185 *      Return
1186 *              0 on success, or a negative error in case of failure.
1187 *
1188 * int bpf_get_stackid(void *ctx, struct bpf_map *map, u64 flags)
1189 *      Description
1190 *              Walk a user or a kernel stack and return its id. To achieve
1191 *              this, the helper needs *ctx*, which is a pointer to the context
1192 *              on which the tracing program is executed, and a pointer to a
1193 *              *map* of type **BPF_MAP_TYPE_STACK_TRACE**.
1194 *
1195 *              The last argument, *flags*, holds the number of stack frames to
1196 *              skip (from 0 to 255), masked with
1197 *              **BPF_F_SKIP_FIELD_MASK**. The next bits can be used to set
1198 *              a combination of the following flags:
1199 *
1200 *              **BPF_F_USER_STACK**
1201 *                      Collect a user space stack instead of a kernel stack.
1202 *              **BPF_F_FAST_STACK_CMP**
1203 *                      Compare stacks by hash only.
1204 *              **BPF_F_REUSE_STACKID**
1205 *                      If two different stacks hash into the same *stackid*,
1206 *                      discard the old one.
1207 *
1208 *              The stack id retrieved is a 32 bit long integer handle which
1209 *              can be further combined with other data (including other stack
1210 *              ids) and used as a key into maps. This can be useful for
1211 *              generating a variety of graphs (such as flame graphs or off-cpu
1212 *              graphs).
1213 *
1214 *              For walking a stack, this helper is an improvement over
1215 *              **bpf_probe_read**\ (), which can be used with unrolled loops
1216 *              but is not efficient and consumes a lot of eBPF instructions.
1217 *              Instead, **bpf_get_stackid**\ () can collect up to
1218 *              **PERF_MAX_STACK_DEPTH** both kernel and user frames. Note that
1219 *              this limit can be controlled with the **sysctl** program, and
1220 *              that it should be manually increased in order to profile long
1221 *              user stacks (such as stacks for Java programs). To do so, use:
1222 *
1223 *              ::
1224 *
1225 *                      # sysctl kernel.perf_event_max_stack=<new value>
1226 *      Return
1227 *              The positive or null stack id on success, or a negative error
1228 *              in case of failure.
1229 *
1230 * s64 bpf_csum_diff(__be32 *from, u32 from_size, __be32 *to, u32 to_size, __wsum seed)
1231 *      Description
1232 *              Compute a checksum difference, from the raw buffer pointed by
1233 *              *from*, of length *from_size* (that must be a multiple of 4),
1234 *              towards the raw buffer pointed by *to*, of size *to_size*
1235 *              (same remark). An optional *seed* can be added to the value
1236 *              (this can be cascaded, the seed may come from a previous call
1237 *              to the helper).
1238 *
1239 *              This is flexible enough to be used in several ways:
1240 *
1241 *              * With *from_size* == 0, *to_size* > 0 and *seed* set to
1242 *                checksum, it can be used when pushing new data.
1243 *              * With *from_size* > 0, *to_size* == 0 and *seed* set to
1244 *                checksum, it can be used when removing data from a packet.
1245 *              * With *from_size* > 0, *to_size* > 0 and *seed* set to 0, it
1246 *                can be used to compute a diff. Note that *from_size* and
1247 *                *to_size* do not need to be equal.
1248 *
1249 *              This helper can be used in combination with
1250 *              **bpf_l3_csum_replace**\ () and **bpf_l4_csum_replace**\ (), to
1251 *              which one can feed in the difference computed with
1252 *              **bpf_csum_diff**\ ().
1253 *      Return
1254 *              The checksum result, or a negative error code in case of
1255 *              failure.
1256 *
1257 * int bpf_skb_get_tunnel_opt(struct sk_buff *skb, void *opt, u32 size)
1258 *      Description
1259 *              Retrieve tunnel options metadata for the packet associated to
1260 *              *skb*, and store the raw tunnel option data to the buffer *opt*
1261 *              of *size*.
1262 *
1263 *              This helper can be used with encapsulation devices that can
1264 *              operate in "collect metadata" mode (please refer to the related
1265 *              note in the description of **bpf_skb_get_tunnel_key**\ () for
1266 *              more details). A particular example where this can be used is
1267 *              in combination with the Geneve encapsulation protocol, where it
1268 *              allows for pushing (with **bpf_skb_get_tunnel_opt**\ () helper)
1269 *              and retrieving arbitrary TLVs (Type-Length-Value headers) from
1270 *              the eBPF program. This allows for full customization of these
1271 *              headers.
1272 *      Return
1273 *              The size of the option data retrieved.
1274 *
1275 * int bpf_skb_set_tunnel_opt(struct sk_buff *skb, void *opt, u32 size)
1276 *      Description
1277 *              Set tunnel options metadata for the packet associated to *skb*
1278 *              to the option data contained in the raw buffer *opt* of *size*.
1279 *
1280 *              See also the description of the **bpf_skb_get_tunnel_opt**\ ()
1281 *              helper for additional information.
1282 *      Return
1283 *              0 on success, or a negative error in case of failure.
1284 *
1285 * int bpf_skb_change_proto(struct sk_buff *skb, __be16 proto, u64 flags)
1286 *      Description
1287 *              Change the protocol of the *skb* to *proto*. Currently
1288 *              supported are transition from IPv4 to IPv6, and from IPv6 to
1289 *              IPv4. The helper takes care of the groundwork for the
1290 *              transition, including resizing the socket buffer. The eBPF
1291 *              program is expected to fill the new headers, if any, via
1292 *              **skb_store_bytes**\ () and to recompute the checksums with
1293 *              **bpf_l3_csum_replace**\ () and **bpf_l4_csum_replace**\
1294 *              (). The main case for this helper is to perform NAT64
1295 *              operations out of an eBPF program.
1296 *
1297 *              Internally, the GSO type is marked as dodgy so that headers are
1298 *              checked and segments are recalculated by the GSO/GRO engine.
1299 *              The size for GSO target is adapted as well.
1300 *
1301 *              All values for *flags* are reserved for future usage, and must
1302 *              be left at zero.
1303 *
1304 *              A call to this helper is susceptible to change the underlying
1305 *              packet buffer. Therefore, at load time, all checks on pointers
1306 *              previously done by the verifier are invalidated and must be
1307 *              performed again, if the helper is used in combination with
1308 *              direct packet access.
1309 *      Return
1310 *              0 on success, or a negative error in case of failure.
1311 *
1312 * int bpf_skb_change_type(struct sk_buff *skb, u32 type)
1313 *      Description
1314 *              Change the packet type for the packet associated to *skb*. This
1315 *              comes down to setting *skb*\ **->pkt_type** to *type*, except
1316 *              the eBPF program does not have a write access to *skb*\
1317 *              **->pkt_type** beside this helper. Using a helper here allows
1318 *              for graceful handling of errors.
1319 *
1320 *              The major use case is to change incoming *skb*s to
1321 *              **PACKET_HOST** in a programmatic way instead of having to
1322 *              recirculate via **redirect**\ (..., **BPF_F_INGRESS**), for
1323 *              example.
1324 *
1325 *              Note that *type* only allows certain values. At this time, they
1326 *              are:
1327 *
1328 *              **PACKET_HOST**
1329 *                      Packet is for us.
1330 *              **PACKET_BROADCAST**
1331 *                      Send packet to all.
1332 *              **PACKET_MULTICAST**
1333 *                      Send packet to group.
1334 *              **PACKET_OTHERHOST**
1335 *                      Send packet to someone else.
1336 *      Return
1337 *              0 on success, or a negative error in case of failure.
1338 *
1339 * int bpf_skb_under_cgroup(struct sk_buff *skb, struct bpf_map *map, u32 index)
1340 *      Description
1341 *              Check whether *skb* is a descendant of the cgroup2 held by
1342 *              *map* of type **BPF_MAP_TYPE_CGROUP_ARRAY**, at *index*.
1343 *      Return
1344 *              The return value depends on the result of the test, and can be:
1345 *
1346 *              * 0, if the *skb* failed the cgroup2 descendant test.
1347 *              * 1, if the *skb* succeeded the cgroup2 descendant test.
1348 *              * A negative error code, if an error occurred.
1349 *
1350 * u32 bpf_get_hash_recalc(struct sk_buff *skb)
1351 *      Description
1352 *              Retrieve the hash of the packet, *skb*\ **->hash**. If it is
1353 *              not set, in particular if the hash was cleared due to mangling,
1354 *              recompute this hash. Later accesses to the hash can be done
1355 *              directly with *skb*\ **->hash**.
1356 *
1357 *              Calling **bpf_set_hash_invalid**\ (), changing a packet
1358 *              prototype with **bpf_skb_change_proto**\ (), or calling
1359 *              **bpf_skb_store_bytes**\ () with the
1360 *              **BPF_F_INVALIDATE_HASH** are actions susceptible to clear
1361 *              the hash and to trigger a new computation for the next call to
1362 *              **bpf_get_hash_recalc**\ ().
1363 *      Return
1364 *              The 32-bit hash.
1365 *
1366 * u64 bpf_get_current_task(void)
1367 *      Return
1368 *              A pointer to the current task struct.
1369 *
1370 * int bpf_probe_write_user(void *dst, const void *src, u32 len)
1371 *      Description
1372 *              Attempt in a safe way to write *len* bytes from the buffer
1373 *              *src* to *dst* in memory. It only works for threads that are in
1374 *              user context, and *dst* must be a valid user space address.
1375 *
1376 *              This helper should not be used to implement any kind of
1377 *              security mechanism because of TOC-TOU attacks, but rather to
1378 *              debug, divert, and manipulate execution of semi-cooperative
1379 *              processes.
1380 *
1381 *              Keep in mind that this feature is meant for experiments, and it
1382 *              has a risk of crashing the system and running programs.
1383 *              Therefore, when an eBPF program using this helper is attached,
1384 *              a warning including PID and process name is printed to kernel
1385 *              logs.
1386 *      Return
1387 *              0 on success, or a negative error in case of failure.
1388 *
1389 * int bpf_current_task_under_cgroup(struct bpf_map *map, u32 index)
1390 *      Description
1391 *              Check whether the probe is being run is the context of a given
1392 *              subset of the cgroup2 hierarchy. The cgroup2 to test is held by
1393 *              *map* of type **BPF_MAP_TYPE_CGROUP_ARRAY**, at *index*.
1394 *      Return
1395 *              The return value depends on the result of the test, and can be:
1396 *
1397 *              * 0, if the *skb* task belongs to the cgroup2.
1398 *              * 1, if the *skb* task does not belong to the cgroup2.
1399 *              * A negative error code, if an error occurred.
1400 *
1401 * int bpf_skb_change_tail(struct sk_buff *skb, u32 len, u64 flags)
1402 *      Description
1403 *              Resize (trim or grow) the packet associated to *skb* to the
1404 *              new *len*. The *flags* are reserved for future usage, and must
1405 *              be left at zero.
1406 *
1407 *              The basic idea is that the helper performs the needed work to
1408 *              change the size of the packet, then the eBPF program rewrites
1409 *              the rest via helpers like **bpf_skb_store_bytes**\ (),
1410 *              **bpf_l3_csum_replace**\ (), **bpf_l3_csum_replace**\ ()
1411 *              and others. This helper is a slow path utility intended for
1412 *              replies with control messages. And because it is targeted for
1413 *              slow path, the helper itself can afford to be slow: it
1414 *              implicitly linearizes, unclones and drops offloads from the
1415 *              *skb*.
1416 *
1417 *              A call to this helper is susceptible to change the underlying
1418 *              packet buffer. Therefore, at load time, all checks on pointers
1419 *              previously done by the verifier are invalidated and must be
1420 *              performed again, if the helper is used in combination with
1421 *              direct packet access.
1422 *      Return
1423 *              0 on success, or a negative error in case of failure.
1424 *
1425 * int bpf_skb_pull_data(struct sk_buff *skb, u32 len)
1426 *      Description
1427 *              Pull in non-linear data in case the *skb* is non-linear and not
1428 *              all of *len* are part of the linear section. Make *len* bytes
1429 *              from *skb* readable and writable. If a zero value is passed for
1430 *              *len*, then the whole length of the *skb* is pulled.
1431 *
1432 *              This helper is only needed for reading and writing with direct
1433 *              packet access.
1434 *
1435 *              For direct packet access, testing that offsets to access
1436 *              are within packet boundaries (test on *skb*\ **->data_end**) is
1437 *              susceptible to fail if offsets are invalid, or if the requested
1438 *              data is in non-linear parts of the *skb*. On failure the
1439 *              program can just bail out, or in the case of a non-linear
1440 *              buffer, use a helper to make the data available. The
1441 *              **bpf_skb_load_bytes**\ () helper is a first solution to access
1442 *              the data. Another one consists in using **bpf_skb_pull_data**
1443 *              to pull in once the non-linear parts, then retesting and
1444 *              eventually access the data.
1445 *
1446 *              At the same time, this also makes sure the *skb* is uncloned,
1447 *              which is a necessary condition for direct write. As this needs
1448 *              to be an invariant for the write part only, the verifier
1449 *              detects writes and adds a prologue that is calling
1450 *              **bpf_skb_pull_data()** to effectively unclone the *skb* from
1451 *              the very beginning in case it is indeed cloned.
1452 *
1453 *              A call to this helper is susceptible to change the underlying
1454 *              packet buffer. Therefore, at load time, all checks on pointers
1455 *              previously done by the verifier are invalidated and must be
1456 *              performed again, if the helper is used in combination with
1457 *              direct packet access.
1458 *      Return
1459 *              0 on success, or a negative error in case of failure.
1460 *
1461 * s64 bpf_csum_update(struct sk_buff *skb, __wsum csum)
1462 *      Description
1463 *              Add the checksum *csum* into *skb*\ **->csum** in case the
1464 *              driver has supplied a checksum for the entire packet into that
1465 *              field. Return an error otherwise. This helper is intended to be
1466 *              used in combination with **bpf_csum_diff**\ (), in particular
1467 *              when the checksum needs to be updated after data has been
1468 *              written into the packet through direct packet access.
1469 *      Return
1470 *              The checksum on success, or a negative error code in case of
1471 *              failure.
1472 *
1473 * void bpf_set_hash_invalid(struct sk_buff *skb)
1474 *      Description
1475 *              Invalidate the current *skb*\ **->hash**. It can be used after
1476 *              mangling on headers through direct packet access, in order to
1477 *              indicate that the hash is outdated and to trigger a
1478 *              recalculation the next time the kernel tries to access this
1479 *              hash or when the **bpf_get_hash_recalc**\ () helper is called.
1480 *
1481 * int bpf_get_numa_node_id(void)
1482 *      Description
1483 *              Return the id of the current NUMA node. The primary use case
1484 *              for this helper is the selection of sockets for the local NUMA
1485 *              node, when the program is attached to sockets using the
1486 *              **SO_ATTACH_REUSEPORT_EBPF** option (see also **socket(7)**),
1487 *              but the helper is also available to other eBPF program types,
1488 *              similarly to **bpf_get_smp_processor_id**\ ().
1489 *      Return
1490 *              The id of current NUMA node.
1491 *
1492 * int bpf_skb_change_head(struct sk_buff *skb, u32 len, u64 flags)
1493 *      Description
1494 *              Grows headroom of packet associated to *skb* and adjusts the
1495 *              offset of the MAC header accordingly, adding *len* bytes of
1496 *              space. It automatically extends and reallocates memory as
1497 *              required.
1498 *
1499 *              This helper can be used on a layer 3 *skb* to push a MAC header
1500 *              for redirection into a layer 2 device.
1501 *
1502 *              All values for *flags* are reserved for future usage, and must
1503 *              be left at zero.
1504 *
1505 *              A call to this helper is susceptible to change the underlying
1506 *              packet buffer. Therefore, at load time, all checks on pointers
1507 *              previously done by the verifier are invalidated and must be
1508 *              performed again, if the helper is used in combination with
1509 *              direct packet access.
1510 *      Return
1511 *              0 on success, or a negative error in case of failure.
1512 *
1513 * int bpf_xdp_adjust_head(struct xdp_buff *xdp_md, int delta)
1514 *      Description
1515 *              Adjust (move) *xdp_md*\ **->data** by *delta* bytes. Note that
1516 *              it is possible to use a negative value for *delta*. This helper
1517 *              can be used to prepare the packet for pushing or popping
1518 *              headers.
1519 *
1520 *              A call to this helper is susceptible to change the underlying
1521 *              packet buffer. Therefore, at load time, all checks on pointers
1522 *              previously done by the verifier are invalidated and must be
1523 *              performed again, if the helper is used in combination with
1524 *              direct packet access.
1525 *      Return
1526 *              0 on success, or a negative error in case of failure.
1527 *
1528 * int bpf_probe_read_str(void *dst, u32 size, const void *unsafe_ptr)
1529 *      Description
1530 *              Copy a NUL terminated string from an unsafe kernel address
1531 *              *unsafe_ptr* to *dst*. See bpf_probe_read_kernel_str() for
1532 *              more details.
1533 *
1534 *              Generally, use bpf_probe_read_user_str() or bpf_probe_read_kernel_str()
1535 *              instead.
1536 *      Return
1537 *              On success, the strictly positive length of the string,
1538 *              including the trailing NUL character. On error, a negative
1539 *              value.
1540 *
1541 * u64 bpf_get_socket_cookie(struct sk_buff *skb)
1542 *      Description
1543 *              If the **struct sk_buff** pointed by *skb* has a known socket,
1544 *              retrieve the cookie (generated by the kernel) of this socket.
1545 *              If no cookie has been set yet, generate a new cookie. Once
1546 *              generated, the socket cookie remains stable for the life of the
1547 *              socket. This helper can be useful for monitoring per socket
1548 *              networking traffic statistics as it provides a global socket
1549 *              identifier that can be assumed unique.
1550 *      Return
1551 *              A 8-byte long non-decreasing number on success, or 0 if the
1552 *              socket field is missing inside *skb*.
1553 *
1554 * u64 bpf_get_socket_cookie(struct bpf_sock_addr *ctx)
1555 *      Description
1556 *              Equivalent to bpf_get_socket_cookie() helper that accepts
1557 *              *skb*, but gets socket from **struct bpf_sock_addr** context.
1558 *      Return
1559 *              A 8-byte long non-decreasing number.
1560 *
1561 * u64 bpf_get_socket_cookie(struct bpf_sock_ops *ctx)
1562 *      Description
1563 *              Equivalent to bpf_get_socket_cookie() helper that accepts
1564 *              *skb*, but gets socket from **struct bpf_sock_ops** context.
1565 *      Return
1566 *              A 8-byte long non-decreasing number.
1567 *
1568 * u32 bpf_get_socket_uid(struct sk_buff *skb)
1569 *      Return
1570 *              The owner UID of the socket associated to *skb*. If the socket
1571 *              is **NULL**, or if it is not a full socket (i.e. if it is a
1572 *              time-wait or a request socket instead), **overflowuid** value
1573 *              is returned (note that **overflowuid** might also be the actual
1574 *              UID value for the socket).
1575 *
1576 * u32 bpf_set_hash(struct sk_buff *skb, u32 hash)
1577 *      Description
1578 *              Set the full hash for *skb* (set the field *skb*\ **->hash**)
1579 *              to value *hash*.
1580 *      Return
1581 *              0
1582 *
1583 * int bpf_setsockopt(struct bpf_sock_ops *bpf_socket, int level, int optname, void *optval, int optlen)
1584 *      Description
1585 *              Emulate a call to **setsockopt()** on the socket associated to
1586 *              *bpf_socket*, which must be a full socket. The *level* at
1587 *              which the option resides and the name *optname* of the option
1588 *              must be specified, see **setsockopt(2)** for more information.
1589 *              The option value of length *optlen* is pointed by *optval*.
1590 *
1591 *              This helper actually implements a subset of **setsockopt()**.
1592 *              It supports the following *level*\ s:
1593 *
1594 *              * **SOL_SOCKET**, which supports the following *optname*\ s:
1595 *                **SO_RCVBUF**, **SO_SNDBUF**, **SO_MAX_PACING_RATE**,
1596 *                **SO_PRIORITY**, **SO_RCVLOWAT**, **SO_MARK**.
1597 *              * **IPPROTO_TCP**, which supports the following *optname*\ s:
1598 *                **TCP_CONGESTION**, **TCP_BPF_IW**,
1599 *                **TCP_BPF_SNDCWND_CLAMP**.
1600 *              * **IPPROTO_IP**, which supports *optname* **IP_TOS**.
1601 *              * **IPPROTO_IPV6**, which supports *optname* **IPV6_TCLASS**.
1602 *      Return
1603 *              0 on success, or a negative error in case of failure.
1604 *
1605 * int bpf_skb_adjust_room(struct sk_buff *skb, s32 len_diff, u32 mode, u64 flags)
1606 *      Description
1607 *              Grow or shrink the room for data in the packet associated to
1608 *              *skb* by *len_diff*, and according to the selected *mode*.
1609 *
1610 *              There are two supported modes at this time:
1611 *
1612 *              * **BPF_ADJ_ROOM_MAC**: Adjust room at the mac layer
1613 *                (room space is added or removed below the layer 2 header).
1614 *
1615 *              * **BPF_ADJ_ROOM_NET**: Adjust room at the network layer
1616 *                (room space is added or removed below the layer 3 header).
1617 *
1618 *              The following flags are supported at this time:
1619 *
1620 *              * **BPF_F_ADJ_ROOM_FIXED_GSO**: Do not adjust gso_size.
1621 *                Adjusting mss in this way is not allowed for datagrams.
1622 *
1623 *              * **BPF_F_ADJ_ROOM_ENCAP_L3_IPV4**,
1624 *                **BPF_F_ADJ_ROOM_ENCAP_L3_IPV6**:
1625 *                Any new space is reserved to hold a tunnel header.
1626 *                Configure skb offsets and other fields accordingly.
1627 *
1628 *              * **BPF_F_ADJ_ROOM_ENCAP_L4_GRE**,
1629 *                **BPF_F_ADJ_ROOM_ENCAP_L4_UDP**:
1630 *                Use with ENCAP_L3 flags to further specify the tunnel type.
1631 *
1632 *              * **BPF_F_ADJ_ROOM_ENCAP_L2**\ (*len*):
1633 *                Use with ENCAP_L3/L4 flags to further specify the tunnel
1634 *                type; *len* is the length of the inner MAC header.
1635 *
1636 *              A call to this helper is susceptible to change the underlying
1637 *              packet buffer. Therefore, at load time, all checks on pointers
1638 *              previously done by the verifier are invalidated and must be
1639 *              performed again, if the helper is used in combination with
1640 *              direct packet access.
1641 *      Return
1642 *              0 on success, or a negative error in case of failure.
1643 *
1644 * int bpf_redirect_map(struct bpf_map *map, u32 key, u64 flags)
1645 *      Description
1646 *              Redirect the packet to the endpoint referenced by *map* at
1647 *              index *key*. Depending on its type, this *map* can contain
1648 *              references to net devices (for forwarding packets through other
1649 *              ports), or to CPUs (for redirecting XDP frames to another CPU;
1650 *              but this is only implemented for native XDP (with driver
1651 *              support) as of this writing).
1652 *
1653 *              The lower two bits of *flags* are used as the return code if
1654 *              the map lookup fails. This is so that the return value can be
1655 *              one of the XDP program return codes up to XDP_TX, as chosen by
1656 *              the caller. Any higher bits in the *flags* argument must be
1657 *              unset.
1658 *
1659 *              See also bpf_redirect(), which only supports redirecting to an
1660 *              ifindex, but doesn't require a map to do so.
1661 *      Return
1662 *              **XDP_REDIRECT** on success, or the value of the two lower bits
1663 *              of the *flags* argument on error.
1664 *
1665 * int bpf_sk_redirect_map(struct sk_buff *skb, struct bpf_map *map, u32 key, u64 flags)
1666 *      Description
1667 *              Redirect the packet to the socket referenced by *map* (of type
1668 *              **BPF_MAP_TYPE_SOCKMAP**) at index *key*. Both ingress and
1669 *              egress interfaces can be used for redirection. The
1670 *              **BPF_F_INGRESS** value in *flags* is used to make the
1671 *              distinction (ingress path is selected if the flag is present,
1672 *              egress path otherwise). This is the only flag supported for now.
1673 *      Return
1674 *              **SK_PASS** on success, or **SK_DROP** on error.
1675 *
1676 * int bpf_sock_map_update(struct bpf_sock_ops *skops, struct bpf_map *map, void *key, u64 flags)
1677 *      Description
1678 *              Add an entry to, or update a *map* referencing sockets. The
1679 *              *skops* is used as a new value for the entry associated to
1680 *              *key*. *flags* is one of:
1681 *
1682 *              **BPF_NOEXIST**
1683 *                      The entry for *key* must not exist in the map.
1684 *              **BPF_EXIST**
1685 *                      The entry for *key* must already exist in the map.
1686 *              **BPF_ANY**
1687 *                      No condition on the existence of the entry for *key*.
1688 *
1689 *              If the *map* has eBPF programs (parser and verdict), those will
1690 *              be inherited by the socket being added. If the socket is
1691 *              already attached to eBPF programs, this results in an error.
1692 *      Return
1693 *              0 on success, or a negative error in case of failure.
1694 *
1695 * int bpf_xdp_adjust_meta(struct xdp_buff *xdp_md, int delta)
1696 *      Description
1697 *              Adjust the address pointed by *xdp_md*\ **->data_meta** by
1698 *              *delta* (which can be positive or negative). Note that this
1699 *              operation modifies the address stored in *xdp_md*\ **->data**,
1700 *              so the latter must be loaded only after the helper has been
1701 *              called.
1702 *
1703 *              The use of *xdp_md*\ **->data_meta** is optional and programs
1704 *              are not required to use it. The rationale is that when the
1705 *              packet is processed with XDP (e.g. as DoS filter), it is
1706 *              possible to push further meta data along with it before passing
1707 *              to the stack, and to give the guarantee that an ingress eBPF
1708 *              program attached as a TC classifier on the same device can pick
1709 *              this up for further post-processing. Since TC works with socket
1710 *              buffers, it remains possible to set from XDP the **mark** or
1711 *              **priority** pointers, or other pointers for the socket buffer.
1712 *              Having this scratch space generic and programmable allows for
1713 *              more flexibility as the user is free to store whatever meta
1714 *              data they need.
1715 *
1716 *              A call to this helper is susceptible to change the underlying
1717 *              packet buffer. Therefore, at load time, all checks on pointers
1718 *              previously done by the verifier are invalidated and must be
1719 *              performed again, if the helper is used in combination with
1720 *              direct packet access.
1721 *      Return
1722 *              0 on success, or a negative error in case of failure.
1723 *
1724 * int bpf_perf_event_read_value(struct bpf_map *map, u64 flags, struct bpf_perf_event_value *buf, u32 buf_size)
1725 *      Description
1726 *              Read the value of a perf event counter, and store it into *buf*
1727 *              of size *buf_size*. This helper relies on a *map* of type
1728 *              **BPF_MAP_TYPE_PERF_EVENT_ARRAY**. The nature of the perf event
1729 *              counter is selected when *map* is updated with perf event file
1730 *              descriptors. The *map* is an array whose size is the number of
1731 *              available CPUs, and each cell contains a value relative to one
1732 *              CPU. The value to retrieve is indicated by *flags*, that
1733 *              contains the index of the CPU to look up, masked with
1734 *              **BPF_F_INDEX_MASK**. Alternatively, *flags* can be set to
1735 *              **BPF_F_CURRENT_CPU** to indicate that the value for the
1736 *              current CPU should be retrieved.
1737 *
1738 *              This helper behaves in a way close to
1739 *              **bpf_perf_event_read**\ () helper, save that instead of
1740 *              just returning the value observed, it fills the *buf*
1741 *              structure. This allows for additional data to be retrieved: in
1742 *              particular, the enabled and running times (in *buf*\
1743 *              **->enabled** and *buf*\ **->running**, respectively) are
1744 *              copied. In general, **bpf_perf_event_read_value**\ () is
1745 *              recommended over **bpf_perf_event_read**\ (), which has some
1746 *              ABI issues and provides fewer functionalities.
1747 *
1748 *              These values are interesting, because hardware PMU (Performance
1749 *              Monitoring Unit) counters are limited resources. When there are
1750 *              more PMU based perf events opened than available counters,
1751 *              kernel will multiplex these events so each event gets certain
1752 *              percentage (but not all) of the PMU time. In case that
1753 *              multiplexing happens, the number of samples or counter value
1754 *              will not reflect the case compared to when no multiplexing
1755 *              occurs. This makes comparison between different runs difficult.
1756 *              Typically, the counter value should be normalized before
1757 *              comparing to other experiments. The usual normalization is done
1758 *              as follows.
1759 *
1760 *              ::
1761 *
1762 *                      normalized_counter = counter * t_enabled / t_running
1763 *
1764 *              Where t_enabled is the time enabled for event and t_running is
1765 *              the time running for event since last normalization. The
1766 *              enabled and running times are accumulated since the perf event
1767 *              open. To achieve scaling factor between two invocations of an
1768 *              eBPF program, users can can use CPU id as the key (which is
1769 *              typical for perf array usage model) to remember the previous
1770 *              value and do the calculation inside the eBPF program.
1771 *      Return
1772 *              0 on success, or a negative error in case of failure.
1773 *
1774 * int bpf_perf_prog_read_value(struct bpf_perf_event_data *ctx, struct bpf_perf_event_value *buf, u32 buf_size)
1775 *      Description
1776 *              For en eBPF program attached to a perf event, retrieve the
1777 *              value of the event counter associated to *ctx* and store it in
1778 *              the structure pointed by *buf* and of size *buf_size*. Enabled
1779 *              and running times are also stored in the structure (see
1780 *              description of helper **bpf_perf_event_read_value**\ () for
1781 *              more details).
1782 *      Return
1783 *              0 on success, or a negative error in case of failure.
1784 *
1785 * int bpf_getsockopt(struct bpf_sock_ops *bpf_socket, int level, int optname, void *optval, int optlen)
1786 *      Description
1787 *              Emulate a call to **getsockopt()** on the socket associated to
1788 *              *bpf_socket*, which must be a full socket. The *level* at
1789 *              which the option resides and the name *optname* of the option
1790 *              must be specified, see **getsockopt(2)** for more information.
1791 *              The retrieved value is stored in the structure pointed by
1792 *              *opval* and of length *optlen*.
1793 *
1794 *              This helper actually implements a subset of **getsockopt()**.
1795 *              It supports the following *level*\ s:
1796 *
1797 *              * **IPPROTO_TCP**, which supports *optname*
1798 *                **TCP_CONGESTION**.
1799 *              * **IPPROTO_IP**, which supports *optname* **IP_TOS**.
1800 *              * **IPPROTO_IPV6**, which supports *optname* **IPV6_TCLASS**.
1801 *      Return
1802 *              0 on success, or a negative error in case of failure.
1803 *
1804 * int bpf_override_return(struct pt_regs *regs, u64 rc)
1805 *      Description
1806 *              Used for error injection, this helper uses kprobes to override
1807 *              the return value of the probed function, and to set it to *rc*.
1808 *              The first argument is the context *regs* on which the kprobe
1809 *              works.
1810 *
1811 *              This helper works by setting setting the PC (program counter)
1812 *              to an override function which is run in place of the original
1813 *              probed function. This means the probed function is not run at
1814 *              all. The replacement function just returns with the required
1815 *              value.
1816 *
1817 *              This helper has security implications, and thus is subject to
1818 *              restrictions. It is only available if the kernel was compiled
1819 *              with the **CONFIG_BPF_KPROBE_OVERRIDE** configuration
1820 *              option, and in this case it only works on functions tagged with
1821 *              **ALLOW_ERROR_INJECTION** in the kernel code.
1822 *
1823 *              Also, the helper is only available for the architectures having
1824 *              the CONFIG_FUNCTION_ERROR_INJECTION option. As of this writing,
1825 *              x86 architecture is the only one to support this feature.
1826 *      Return
1827 *              0
1828 *
1829 * int bpf_sock_ops_cb_flags_set(struct bpf_sock_ops *bpf_sock, int argval)
1830 *      Description
1831 *              Attempt to set the value of the **bpf_sock_ops_cb_flags** field
1832 *              for the full TCP socket associated to *bpf_sock_ops* to
1833 *              *argval*.
1834 *
1835 *              The primary use of this field is to determine if there should
1836 *              be calls to eBPF programs of type
1837 *              **BPF_PROG_TYPE_SOCK_OPS** at various points in the TCP
1838 *              code. A program of the same type can change its value, per
1839 *              connection and as necessary, when the connection is
1840 *              established. This field is directly accessible for reading, but
1841 *              this helper must be used for updates in order to return an
1842 *              error if an eBPF program tries to set a callback that is not
1843 *              supported in the current kernel.
1844 *
1845 *              *argval* is a flag array which can combine these flags:
1846 *
1847 *              * **BPF_SOCK_OPS_RTO_CB_FLAG** (retransmission time out)
1848 *              * **BPF_SOCK_OPS_RETRANS_CB_FLAG** (retransmission)
1849 *              * **BPF_SOCK_OPS_STATE_CB_FLAG** (TCP state change)
1850 *              * **BPF_SOCK_OPS_RTT_CB_FLAG** (every RTT)
1851 *
1852 *              Therefore, this function can be used to clear a callback flag by
1853 *              setting the appropriate bit to zero. e.g. to disable the RTO
1854 *              callback:
1855 *
1856 *              **bpf_sock_ops_cb_flags_set(bpf_sock,**
1857 *                      **bpf_sock->bpf_sock_ops_cb_flags & ~BPF_SOCK_OPS_RTO_CB_FLAG)**
1858 *
1859 *              Here are some examples of where one could call such eBPF
1860 *              program:
1861 *
1862 *              * When RTO fires.
1863 *              * When a packet is retransmitted.
1864 *              * When the connection terminates.
1865 *              * When a packet is sent.
1866 *              * When a packet is received.
1867 *      Return
1868 *              Code **-EINVAL** if the socket is not a full TCP socket;
1869 *              otherwise, a positive number containing the bits that could not
1870 *              be set is returned (which comes down to 0 if all bits were set
1871 *              as required).
1872 *
1873 * int bpf_msg_redirect_map(struct sk_msg_buff *msg, struct bpf_map *map, u32 key, u64 flags)
1874 *      Description
1875 *              This helper is used in programs implementing policies at the
1876 *              socket level. If the message *msg* is allowed to pass (i.e. if
1877 *              the verdict eBPF program returns **SK_PASS**), redirect it to
1878 *              the socket referenced by *map* (of type
1879 *              **BPF_MAP_TYPE_SOCKMAP**) at index *key*. Both ingress and
1880 *              egress interfaces can be used for redirection. The
1881 *              **BPF_F_INGRESS** value in *flags* is used to make the
1882 *              distinction (ingress path is selected if the flag is present,
1883 *              egress path otherwise). This is the only flag supported for now.
1884 *      Return
1885 *              **SK_PASS** on success, or **SK_DROP** on error.
1886 *
1887 * int bpf_msg_apply_bytes(struct sk_msg_buff *msg, u32 bytes)
1888 *      Description
1889 *              For socket policies, apply the verdict of the eBPF program to
1890 *              the next *bytes* (number of bytes) of message *msg*.
1891 *
1892 *              For example, this helper can be used in the following cases:
1893 *
1894 *              * A single **sendmsg**\ () or **sendfile**\ () system call
1895 *                contains multiple logical messages that the eBPF program is
1896 *                supposed to read and for which it should apply a verdict.
1897 *              * An eBPF program only cares to read the first *bytes* of a
1898 *                *msg*. If the message has a large payload, then setting up
1899 *                and calling the eBPF program repeatedly for all bytes, even
1900 *                though the verdict is already known, would create unnecessary
1901 *                overhead.
1902 *
1903 *              When called from within an eBPF program, the helper sets a
1904 *              counter internal to the BPF infrastructure, that is used to
1905 *              apply the last verdict to the next *bytes*. If *bytes* is
1906 *              smaller than the current data being processed from a
1907 *              **sendmsg**\ () or **sendfile**\ () system call, the first
1908 *              *bytes* will be sent and the eBPF program will be re-run with
1909 *              the pointer for start of data pointing to byte number *bytes*
1910 *              **+ 1**. If *bytes* is larger than the current data being
1911 *              processed, then the eBPF verdict will be applied to multiple
1912 *              **sendmsg**\ () or **sendfile**\ () calls until *bytes* are
1913 *              consumed.
1914 *
1915 *              Note that if a socket closes with the internal counter holding
1916 *              a non-zero value, this is not a problem because data is not
1917 *              being buffered for *bytes* and is sent as it is received.
1918 *      Return
1919 *              0
1920 *
1921 * int bpf_msg_cork_bytes(struct sk_msg_buff *msg, u32 bytes)
1922 *      Description
1923 *              For socket policies, prevent the execution of the verdict eBPF
1924 *              program for message *msg* until *bytes* (byte number) have been
1925 *              accumulated.
1926 *
1927 *              This can be used when one needs a specific number of bytes
1928 *              before a verdict can be assigned, even if the data spans
1929 *              multiple **sendmsg**\ () or **sendfile**\ () calls. The extreme
1930 *              case would be a user calling **sendmsg**\ () repeatedly with
1931 *              1-byte long message segments. Obviously, this is bad for
1932 *              performance, but it is still valid. If the eBPF program needs
1933 *              *bytes* bytes to validate a header, this helper can be used to
1934 *              prevent the eBPF program to be called again until *bytes* have
1935 *              been accumulated.
1936 *      Return
1937 *              0
1938 *
1939 * int bpf_msg_pull_data(struct sk_msg_buff *msg, u32 start, u32 end, u64 flags)
1940 *      Description
1941 *              For socket policies, pull in non-linear data from user space
1942 *              for *msg* and set pointers *msg*\ **->data** and *msg*\
1943 *              **->data_end** to *start* and *end* bytes offsets into *msg*,
1944 *              respectively.
1945 *
1946 *              If a program of type **BPF_PROG_TYPE_SK_MSG** is run on a
1947 *              *msg* it can only parse data that the (**data**, **data_end**)
1948 *              pointers have already consumed. For **sendmsg**\ () hooks this
1949 *              is likely the first scatterlist element. But for calls relying
1950 *              on the **sendpage** handler (e.g. **sendfile**\ ()) this will
1951 *              be the range (**0**, **0**) because the data is shared with
1952 *              user space and by default the objective is to avoid allowing
1953 *              user space to modify data while (or after) eBPF verdict is
1954 *              being decided. This helper can be used to pull in data and to
1955 *              set the start and end pointer to given values. Data will be
1956 *              copied if necessary (i.e. if data was not linear and if start
1957 *              and end pointers do not point to the same chunk).
1958 *
1959 *              A call to this helper is susceptible to change the underlying
1960 *              packet buffer. Therefore, at load time, all checks on pointers
1961 *              previously done by the verifier are invalidated and must be
1962 *              performed again, if the helper is used in combination with
1963 *              direct packet access.
1964 *
1965 *              All values for *flags* are reserved for future usage, and must
1966 *              be left at zero.
1967 *      Return
1968 *              0 on success, or a negative error in case of failure.
1969 *
1970 * int bpf_bind(struct bpf_sock_addr *ctx, struct sockaddr *addr, int addr_len)
1971 *      Description
1972 *              Bind the socket associated to *ctx* to the address pointed by
1973 *              *addr*, of length *addr_len*. This allows for making outgoing
1974 *              connection from the desired IP address, which can be useful for
1975 *              example when all processes inside a cgroup should use one
1976 *              single IP address on a host that has multiple IP configured.
1977 *
1978 *              This helper works for IPv4 and IPv6, TCP and UDP sockets. The
1979 *              domain (*addr*\ **->sa_family**) must be **AF_INET** (or
1980 *              **AF_INET6**). Looking for a free port to bind to can be
1981 *              expensive, therefore binding to port is not permitted by the
1982 *              helper: *addr*\ **->sin_port** (or **sin6_port**, respectively)
1983 *              must be set to zero.
1984 *      Return
1985 *              0 on success, or a negative error in case of failure.
1986 *
1987 * int bpf_xdp_adjust_tail(struct xdp_buff *xdp_md, int delta)
1988 *      Description
1989 *              Adjust (move) *xdp_md*\ **->data_end** by *delta* bytes. It is
1990 *              only possible to shrink the packet as of this writing,
1991 *              therefore *delta* must be a negative integer.
1992 *
1993 *              A call to this helper is susceptible to change the underlying
1994 *              packet buffer. Therefore, at load time, all checks on pointers
1995 *              previously done by the verifier are invalidated and must be
1996 *              performed again, if the helper is used in combination with
1997 *              direct packet access.
1998 *      Return
1999 *              0 on success, or a negative error in case of failure.
2000 *
2001 * int bpf_skb_get_xfrm_state(struct sk_buff *skb, u32 index, struct bpf_xfrm_state *xfrm_state, u32 size, u64 flags)
2002 *      Description
2003 *              Retrieve the XFRM state (IP transform framework, see also
2004 *              **ip-xfrm(8)**) at *index* in XFRM "security path" for *skb*.
2005 *
2006 *              The retrieved value is stored in the **struct bpf_xfrm_state**
2007 *              pointed by *xfrm_state* and of length *size*.
2008 *
2009 *              All values for *flags* are reserved for future usage, and must
2010 *              be left at zero.
2011 *
2012 *              This helper is available only if the kernel was compiled with
2013 *              **CONFIG_XFRM** configuration option.
2014 *      Return
2015 *              0 on success, or a negative error in case of failure.
2016 *
2017 * int bpf_get_stack(void *ctx, void *buf, u32 size, u64 flags)
2018 *      Description
2019 *              Return a user or a kernel stack in bpf program provided buffer.
2020 *              To achieve this, the helper needs *ctx*, which is a pointer
2021 *              to the context on which the tracing program is executed.
2022 *              To store the stacktrace, the bpf program provides *buf* with
2023 *              a nonnegative *size*.
2024 *
2025 *              The last argument, *flags*, holds the number of stack frames to
2026 *              skip (from 0 to 255), masked with
2027 *              **BPF_F_SKIP_FIELD_MASK**. The next bits can be used to set
2028 *              the following flags:
2029 *
2030 *              **BPF_F_USER_STACK**
2031 *                      Collect a user space stack instead of a kernel stack.
2032 *              **BPF_F_USER_BUILD_ID**
2033 *                      Collect buildid+offset instead of ips for user stack,
2034 *                      only valid if **BPF_F_USER_STACK** is also specified.
2035 *
2036 *              **bpf_get_stack**\ () can collect up to
2037 *              **PERF_MAX_STACK_DEPTH** both kernel and user frames, subject
2038 *              to sufficient large buffer size. Note that
2039 *              this limit can be controlled with the **sysctl** program, and
2040 *              that it should be manually increased in order to profile long
2041 *              user stacks (such as stacks for Java programs). To do so, use:
2042 *
2043 *              ::
2044 *
2045 *                      # sysctl kernel.perf_event_max_stack=<new value>
2046 *      Return
2047 *              A non-negative value equal to or less than *size* on success,
2048 *              or a negative error in case of failure.
2049 *
2050 * int bpf_skb_load_bytes_relative(const void *skb, u32 offset, void *to, u32 len, u32 start_header)
2051 *      Description
2052 *              This helper is similar to **bpf_skb_load_bytes**\ () in that
2053 *              it provides an easy way to load *len* bytes from *offset*
2054 *              from the packet associated to *skb*, into the buffer pointed
2055 *              by *to*. The difference to **bpf_skb_load_bytes**\ () is that
2056 *              a fifth argument *start_header* exists in order to select a
2057 *              base offset to start from. *start_header* can be one of:
2058 *
2059 *              **BPF_HDR_START_MAC**
2060 *                      Base offset to load data from is *skb*'s mac header.
2061 *              **BPF_HDR_START_NET**
2062 *                      Base offset to load data from is *skb*'s network header.
2063 *
2064 *              In general, "direct packet access" is the preferred method to
2065 *              access packet data, however, this helper is in particular useful
2066 *              in socket filters where *skb*\ **->data** does not always point
2067 *              to the start of the mac header and where "direct packet access"
2068 *              is not available.
2069 *      Return
2070 *              0 on success, or a negative error in case of failure.
2071 *
2072 * int bpf_fib_lookup(void *ctx, struct bpf_fib_lookup *params, int plen, u32 flags)
2073 *      Description
2074 *              Do FIB lookup in kernel tables using parameters in *params*.
2075 *              If lookup is successful and result shows packet is to be
2076 *              forwarded, the neighbor tables are searched for the nexthop.
2077 *              If successful (ie., FIB lookup shows forwarding and nexthop
2078 *              is resolved), the nexthop address is returned in ipv4_dst
2079 *              or ipv6_dst based on family, smac is set to mac address of
2080 *              egress device, dmac is set to nexthop mac address, rt_metric
2081 *              is set to metric from route (IPv4/IPv6 only), and ifindex
2082 *              is set to the device index of the nexthop from the FIB lookup.
2083 *
2084 *              *plen* argument is the size of the passed in struct.
2085 *              *flags* argument can be a combination of one or more of the
2086 *              following values:
2087 *
2088 *              **BPF_FIB_LOOKUP_DIRECT**
2089 *                      Do a direct table lookup vs full lookup using FIB
2090 *                      rules.
2091 *              **BPF_FIB_LOOKUP_OUTPUT**
2092 *                      Perform lookup from an egress perspective (default is
2093 *                      ingress).
2094 *
2095 *              *ctx* is either **struct xdp_md** for XDP programs or
2096 *              **struct sk_buff** tc cls_act programs.
2097 *      Return
2098 *              * < 0 if any input argument is invalid
2099 *              *   0 on success (packet is forwarded, nexthop neighbor exists)
2100 *              * > 0 one of **BPF_FIB_LKUP_RET_** codes explaining why the
2101 *                packet is not forwarded or needs assist from full stack
2102 *
2103 * int bpf_sock_hash_update(struct bpf_sock_ops *skops, struct bpf_map *map, void *key, u64 flags)
2104 *      Description
2105 *              Add an entry to, or update a sockhash *map* referencing sockets.
2106 *              The *skops* is used as a new value for the entry associated to
2107 *              *key*. *flags* is one of:
2108 *
2109 *              **BPF_NOEXIST**
2110 *                      The entry for *key* must not exist in the map.
2111 *              **BPF_EXIST**
2112 *                      The entry for *key* must already exist in the map.
2113 *              **BPF_ANY**
2114 *                      No condition on the existence of the entry for *key*.
2115 *
2116 *              If the *map* has eBPF programs (parser and verdict), those will
2117 *              be inherited by the socket being added. If the socket is
2118 *              already attached to eBPF programs, this results in an error.
2119 *      Return
2120 *              0 on success, or a negative error in case of failure.
2121 *
2122 * int bpf_msg_redirect_hash(struct sk_msg_buff *msg, struct bpf_map *map, void *key, u64 flags)
2123 *      Description
2124 *              This helper is used in programs implementing policies at the
2125 *              socket level. If the message *msg* is allowed to pass (i.e. if
2126 *              the verdict eBPF program returns **SK_PASS**), redirect it to
2127 *              the socket referenced by *map* (of type
2128 *              **BPF_MAP_TYPE_SOCKHASH**) using hash *key*. Both ingress and
2129 *              egress interfaces can be used for redirection. The
2130 *              **BPF_F_INGRESS** value in *flags* is used to make the
2131 *              distinction (ingress path is selected if the flag is present,
2132 *              egress path otherwise). This is the only flag supported for now.
2133 *      Return
2134 *              **SK_PASS** on success, or **SK_DROP** on error.
2135 *
2136 * int bpf_sk_redirect_hash(struct sk_buff *skb, struct bpf_map *map, void *key, u64 flags)
2137 *      Description
2138 *              This helper is used in programs implementing policies at the
2139 *              skb socket level. If the sk_buff *skb* is allowed to pass (i.e.
2140 *              if the verdeict eBPF program returns **SK_PASS**), redirect it
2141 *              to the socket referenced by *map* (of type
2142 *              **BPF_MAP_TYPE_SOCKHASH**) using hash *key*. Both ingress and
2143 *              egress interfaces can be used for redirection. The
2144 *              **BPF_F_INGRESS** value in *flags* is used to make the
2145 *              distinction (ingress path is selected if the flag is present,
2146 *              egress otherwise). This is the only flag supported for now.
2147 *      Return
2148 *              **SK_PASS** on success, or **SK_DROP** on error.
2149 *
2150 * int bpf_lwt_push_encap(struct sk_buff *skb, u32 type, void *hdr, u32 len)
2151 *      Description
2152 *              Encapsulate the packet associated to *skb* within a Layer 3
2153 *              protocol header. This header is provided in the buffer at
2154 *              address *hdr*, with *len* its size in bytes. *type* indicates
2155 *              the protocol of the header and can be one of:
2156 *
2157 *              **BPF_LWT_ENCAP_SEG6**
2158 *                      IPv6 encapsulation with Segment Routing Header
2159 *                      (**struct ipv6_sr_hdr**). *hdr* only contains the SRH,
2160 *                      the IPv6 header is computed by the kernel.
2161 *              **BPF_LWT_ENCAP_SEG6_INLINE**
2162 *                      Only works if *skb* contains an IPv6 packet. Insert a
2163 *                      Segment Routing Header (**struct ipv6_sr_hdr**) inside
2164 *                      the IPv6 header.
2165 *              **BPF_LWT_ENCAP_IP**
2166 *                      IP encapsulation (GRE/GUE/IPIP/etc). The outer header
2167 *                      must be IPv4 or IPv6, followed by zero or more
2168 *                      additional headers, up to **LWT_BPF_MAX_HEADROOM**
2169 *                      total bytes in all prepended headers. Please note that
2170 *                      if **skb_is_gso**\ (*skb*) is true, no more than two
2171 *                      headers can be prepended, and the inner header, if
2172 *                      present, should be either GRE or UDP/GUE.
2173 *
2174 *              **BPF_LWT_ENCAP_SEG6**\ \* types can be called by BPF programs
2175 *              of type **BPF_PROG_TYPE_LWT_IN**; **BPF_LWT_ENCAP_IP** type can
2176 *              be called by bpf programs of types **BPF_PROG_TYPE_LWT_IN** and
2177 *              **BPF_PROG_TYPE_LWT_XMIT**.
2178 *
2179 *              A call to this helper is susceptible to change the underlying
2180 *              packet buffer. Therefore, at load time, all checks on pointers
2181 *              previously done by the verifier are invalidated and must be
2182 *              performed again, if the helper is used in combination with
2183 *              direct packet access.
2184 *      Return
2185 *              0 on success, or a negative error in case of failure.
2186 *
2187 * int bpf_lwt_seg6_store_bytes(struct sk_buff *skb, u32 offset, const void *from, u32 len)
2188 *      Description
2189 *              Store *len* bytes from address *from* into the packet
2190 *              associated to *skb*, at *offset*. Only the flags, tag and TLVs
2191 *              inside the outermost IPv6 Segment Routing Header can be
2192 *              modified through this helper.
2193 *
2194 *              A call to this helper is susceptible to change the underlying
2195 *              packet buffer. Therefore, at load time, all checks on pointers
2196 *              previously done by the verifier are invalidated and must be
2197 *              performed again, if the helper is used in combination with
2198 *              direct packet access.
2199 *      Return
2200 *              0 on success, or a negative error in case of failure.
2201 *
2202 * int bpf_lwt_seg6_adjust_srh(struct sk_buff *skb, u32 offset, s32 delta)
2203 *      Description
2204 *              Adjust the size allocated to TLVs in the outermost IPv6
2205 *              Segment Routing Header contained in the packet associated to
2206 *              *skb*, at position *offset* by *delta* bytes. Only offsets
2207 *              after the segments are accepted. *delta* can be as well
2208 *              positive (growing) as negative (shrinking).
2209 *
2210 *              A call to this helper is susceptible to change the underlying
2211 *              packet buffer. Therefore, at load time, all checks on pointers
2212 *              previously done by the verifier are invalidated and must be
2213 *              performed again, if the helper is used in combination with
2214 *              direct packet access.
2215 *      Return
2216 *              0 on success, or a negative error in case of failure.
2217 *
2218 * int bpf_lwt_seg6_action(struct sk_buff *skb, u32 action, void *param, u32 param_len)
2219 *      Description
2220 *              Apply an IPv6 Segment Routing action of type *action* to the
2221 *              packet associated to *skb*. Each action takes a parameter
2222 *              contained at address *param*, and of length *param_len* bytes.
2223 *              *action* can be one of:
2224 *
2225 *              **SEG6_LOCAL_ACTION_END_X**
2226 *                      End.X action: Endpoint with Layer-3 cross-connect.
2227 *                      Type of *param*: **struct in6_addr**.
2228 *              **SEG6_LOCAL_ACTION_END_T**
2229 *                      End.T action: Endpoint with specific IPv6 table lookup.
2230 *                      Type of *param*: **int**.
2231 *              **SEG6_LOCAL_ACTION_END_B6**
2232 *                      End.B6 action: Endpoint bound to an SRv6 policy.
2233 *                      Type of *param*: **struct ipv6_sr_hdr**.
2234 *              **SEG6_LOCAL_ACTION_END_B6_ENCAP**
2235 *                      End.B6.Encap action: Endpoint bound to an SRv6
2236 *                      encapsulation policy.
2237 *                      Type of *param*: **struct ipv6_sr_hdr**.
2238 *
2239 *              A call to this helper is susceptible to change the underlying
2240 *              packet buffer. Therefore, at load time, all checks on pointers
2241 *              previously done by the verifier are invalidated and must be
2242 *              performed again, if the helper is used in combination with
2243 *              direct packet access.
2244 *      Return
2245 *              0 on success, or a negative error in case of failure.
2246 *
2247 * int bpf_rc_repeat(void *ctx)
2248 *      Description
2249 *              This helper is used in programs implementing IR decoding, to
2250 *              report a successfully decoded repeat key message. This delays
2251 *              the generation of a key up event for previously generated
2252 *              key down event.
2253 *
2254 *              Some IR protocols like NEC have a special IR message for
2255 *              repeating last button, for when a button is held down.
2256 *
2257 *              The *ctx* should point to the lirc sample as passed into
2258 *              the program.
2259 *
2260 *              This helper is only available is the kernel was compiled with
2261 *              the **CONFIG_BPF_LIRC_MODE2** configuration option set to
2262 *              "**y**".
2263 *      Return
2264 *              0
2265 *
2266 * int bpf_rc_keydown(void *ctx, u32 protocol, u64 scancode, u32 toggle)
2267 *      Description
2268 *              This helper is used in programs implementing IR decoding, to
2269 *              report a successfully decoded key press with *scancode*,
2270 *              *toggle* value in the given *protocol*. The scancode will be
2271 *              translated to a keycode using the rc keymap, and reported as
2272 *              an input key down event. After a period a key up event is
2273 *              generated. This period can be extended by calling either
2274 *              **bpf_rc_keydown**\ () again with the same values, or calling
2275 *              **bpf_rc_repeat**\ ().
2276 *
2277 *              Some protocols include a toggle bit, in case the button was
2278 *              released and pressed again between consecutive scancodes.
2279 *
2280 *              The *ctx* should point to the lirc sample as passed into
2281 *              the program.
2282 *
2283 *              The *protocol* is the decoded protocol number (see
2284 *              **enum rc_proto** for some predefined values).
2285 *
2286 *              This helper is only available is the kernel was compiled with
2287 *              the **CONFIG_BPF_LIRC_MODE2** configuration option set to
2288 *              "**y**".
2289 *      Return
2290 *              0
2291 *
2292 * u64 bpf_skb_cgroup_id(struct sk_buff *skb)
2293 *      Description
2294 *              Return the cgroup v2 id of the socket associated with the *skb*.
2295 *              This is roughly similar to the **bpf_get_cgroup_classid**\ ()
2296 *              helper for cgroup v1 by providing a tag resp. identifier that
2297 *              can be matched on or used for map lookups e.g. to implement
2298 *              policy. The cgroup v2 id of a given path in the hierarchy is
2299 *              exposed in user space through the f_handle API in order to get
2300 *              to the same 64-bit id.
2301 *
2302 *              This helper can be used on TC egress path, but not on ingress,
2303 *              and is available only if the kernel was compiled with the
2304 *              **CONFIG_SOCK_CGROUP_DATA** configuration option.
2305 *      Return
2306 *              The id is returned or 0 in case the id could not be retrieved.
2307 *
2308 * u64 bpf_get_current_cgroup_id(void)
2309 *      Return
2310 *              A 64-bit integer containing the current cgroup id based
2311 *              on the cgroup within which the current task is running.
2312 *
2313 * void *bpf_get_local_storage(void *map, u64 flags)
2314 *      Description
2315 *              Get the pointer to the local storage area.
2316 *              The type and the size of the local storage is defined
2317 *              by the *map* argument.
2318 *              The *flags* meaning is specific for each map type,
2319 *              and has to be 0 for cgroup local storage.
2320 *
2321 *              Depending on the BPF program type, a local storage area
2322 *              can be shared between multiple instances of the BPF program,
2323 *              running simultaneously.
2324 *
2325 *              A user should care about the synchronization by himself.
2326 *              For example, by using the **BPF_STX_XADD** instruction to alter
2327 *              the shared data.
2328 *      Return
2329 *              A pointer to the local storage area.
2330 *
2331 * int bpf_sk_select_reuseport(struct sk_reuseport_md *reuse, struct bpf_map *map, void *key, u64 flags)
2332 *      Description
2333 *              Select a **SO_REUSEPORT** socket from a
2334 *              **BPF_MAP_TYPE_REUSEPORT_ARRAY** *map*.
2335 *              It checks the selected socket is matching the incoming
2336 *              request in the socket buffer.
2337 *      Return
2338 *              0 on success, or a negative error in case of failure.
2339 *
2340 * u64 bpf_skb_ancestor_cgroup_id(struct sk_buff *skb, int ancestor_level)
2341 *      Description
2342 *              Return id of cgroup v2 that is ancestor of cgroup associated
2343 *              with the *skb* at the *ancestor_level*.  The root cgroup is at
2344 *              *ancestor_level* zero and each step down the hierarchy
2345 *              increments the level. If *ancestor_level* == level of cgroup
2346 *              associated with *skb*, then return value will be same as that
2347 *              of **bpf_skb_cgroup_id**\ ().
2348 *
2349 *              The helper is useful to implement policies based on cgroups
2350 *              that are upper in hierarchy than immediate cgroup associated
2351 *              with *skb*.
2352 *
2353 *              The format of returned id and helper limitations are same as in
2354 *              **bpf_skb_cgroup_id**\ ().
2355 *      Return
2356 *              The id is returned or 0 in case the id could not be retrieved.
2357 *
2358 * struct bpf_sock *bpf_sk_lookup_tcp(void *ctx, struct bpf_sock_tuple *tuple, u32 tuple_size, u64 netns, u64 flags)
2359 *      Description
2360 *              Look for TCP socket matching *tuple*, optionally in a child
2361 *              network namespace *netns*. The return value must be checked,
2362 *              and if non-**NULL**, released via **bpf_sk_release**\ ().
2363 *
2364 *              The *ctx* should point to the context of the program, such as
2365 *              the skb or socket (depending on the hook in use). This is used
2366 *              to determine the base network namespace for the lookup.
2367 *
2368 *              *tuple_size* must be one of:
2369 *
2370 *              **sizeof**\ (*tuple*\ **->ipv4**)
2371 *                      Look for an IPv4 socket.
2372 *              **sizeof**\ (*tuple*\ **->ipv6**)
2373 *                      Look for an IPv6 socket.
2374 *
2375 *              If the *netns* is a negative signed 32-bit integer, then the
2376 *              socket lookup table in the netns associated with the *ctx* will
2377 *              will be used. For the TC hooks, this is the netns of the device
2378 *              in the skb. For socket hooks, this is the netns of the socket.
2379 *              If *netns* is any other signed 32-bit value greater than or
2380 *              equal to zero then it specifies the ID of the netns relative to
2381 *              the netns associated with the *ctx*. *netns* values beyond the
2382 *              range of 32-bit integers are reserved for future use.
2383 *
2384 *              All values for *flags* are reserved for future usage, and must
2385 *              be left at zero.
2386 *
2387 *              This helper is available only if the kernel was compiled with
2388 *              **CONFIG_NET** configuration option.
2389 *      Return
2390 *              Pointer to **struct bpf_sock**, or **NULL** in case of failure.
2391 *              For sockets with reuseport option, the **struct bpf_sock**
2392 *              result is from *reuse*\ **->socks**\ [] using the hash of the
2393 *              tuple.
2394 *
2395 * struct bpf_sock *bpf_sk_lookup_udp(void *ctx, struct bpf_sock_tuple *tuple, u32 tuple_size, u64 netns, u64 flags)
2396 *      Description
2397 *              Look for UDP socket matching *tuple*, optionally in a child
2398 *              network namespace *netns*. The return value must be checked,
2399 *              and if non-**NULL**, released via **bpf_sk_release**\ ().
2400 *
2401 *              The *ctx* should point to the context of the program, such as
2402 *              the skb or socket (depending on the hook in use). This is used
2403 *              to determine the base network namespace for the lookup.
2404 *
2405 *              *tuple_size* must be one of:
2406 *
2407 *              **sizeof**\ (*tuple*\ **->ipv4**)
2408 *                      Look for an IPv4 socket.
2409 *              **sizeof**\ (*tuple*\ **->ipv6**)
2410 *                      Look for an IPv6 socket.
2411 *
2412 *              If the *netns* is a negative signed 32-bit integer, then the
2413 *              socket lookup table in the netns associated with the *ctx* will
2414 *              will be used. For the TC hooks, this is the netns of the device
2415 *              in the skb. For socket hooks, this is the netns of the socket.
2416 *              If *netns* is any other signed 32-bit value greater than or
2417 *              equal to zero then it specifies the ID of the netns relative to
2418 *              the netns associated with the *ctx*. *netns* values beyond the
2419 *              range of 32-bit integers are reserved for future use.
2420 *
2421 *              All values for *flags* are reserved for future usage, and must
2422 *              be left at zero.
2423 *
2424 *              This helper is available only if the kernel was compiled with
2425 *              **CONFIG_NET** configuration option.
2426 *      Return
2427 *              Pointer to **struct bpf_sock**, or **NULL** in case of failure.
2428 *              For sockets with reuseport option, the **struct bpf_sock**
2429 *              result is from *reuse*\ **->socks**\ [] using the hash of the
2430 *              tuple.
2431 *
2432 * int bpf_sk_release(struct bpf_sock *sock)
2433 *      Description
2434 *              Release the reference held by *sock*. *sock* must be a
2435 *              non-**NULL** pointer that was returned from
2436 *              **bpf_sk_lookup_xxx**\ ().
2437 *      Return
2438 *              0 on success, or a negative error in case of failure.
2439 *
2440 * int bpf_map_push_elem(struct bpf_map *map, const void *value, u64 flags)
2441 *      Description
2442 *              Push an element *value* in *map*. *flags* is one of:
2443 *
2444 *              **BPF_EXIST**
2445 *                      If the queue/stack is full, the oldest element is
2446 *                      removed to make room for this.
2447 *      Return
2448 *              0 on success, or a negative error in case of failure.
2449 *
2450 * int bpf_map_pop_elem(struct bpf_map *map, void *value)
2451 *      Description
2452 *              Pop an element from *map*.
2453 *      Return
2454 *              0 on success, or a negative error in case of failure.
2455 *
2456 * int bpf_map_peek_elem(struct bpf_map *map, void *value)
2457 *      Description
2458 *              Get an element from *map* without removing it.
2459 *      Return
2460 *              0 on success, or a negative error in case of failure.
2461 *
2462 * int bpf_msg_push_data(struct sk_msg_buff *msg, u32 start, u32 len, u64 flags)
2463 *      Description
2464 *              For socket policies, insert *len* bytes into *msg* at offset
2465 *              *start*.
2466 *
2467 *              If a program of type **BPF_PROG_TYPE_SK_MSG** is run on a
2468 *              *msg* it may want to insert metadata or options into the *msg*.
2469 *              This can later be read and used by any of the lower layer BPF
2470 *              hooks.
2471 *
2472 *              This helper may fail if under memory pressure (a malloc
2473 *              fails) in these cases BPF programs will get an appropriate
2474 *              error and BPF programs will need to handle them.
2475 *      Return
2476 *              0 on success, or a negative error in case of failure.
2477 *
2478 * int bpf_msg_pop_data(struct sk_msg_buff *msg, u32 start, u32 len, u64 flags)
2479 *      Description
2480 *              Will remove *len* bytes from a *msg* starting at byte *start*.
2481 *              This may result in **ENOMEM** errors under certain situations if
2482 *              an allocation and copy are required due to a full ring buffer.
2483 *              However, the helper will try to avoid doing the allocation
2484 *              if possible. Other errors can occur if input parameters are
2485 *              invalid either due to *start* byte not being valid part of *msg*
2486 *              payload and/or *pop* value being to large.
2487 *      Return
2488 *              0 on success, or a negative error in case of failure.
2489 *
2490 * int bpf_rc_pointer_rel(void *ctx, s32 rel_x, s32 rel_y)
2491 *      Description
2492 *              This helper is used in programs implementing IR decoding, to
2493 *              report a successfully decoded pointer movement.
2494 *
2495 *              The *ctx* should point to the lirc sample as passed into
2496 *              the program.
2497 *
2498 *              This helper is only available is the kernel was compiled with
2499 *              the **CONFIG_BPF_LIRC_MODE2** configuration option set to
2500 *              "**y**".
2501 *      Return
2502 *              0
2503 *
2504 * int bpf_spin_lock(struct bpf_spin_lock *lock)
2505 *      Description
2506 *              Acquire a spinlock represented by the pointer *lock*, which is
2507 *              stored as part of a value of a map. Taking the lock allows to
2508 *              safely update the rest of the fields in that value. The
2509 *              spinlock can (and must) later be released with a call to
2510 *              **bpf_spin_unlock**\ (\ *lock*\ ).
2511 *
2512 *              Spinlocks in BPF programs come with a number of restrictions
2513 *              and constraints:
2514 *
2515 *              * **bpf_spin_lock** objects are only allowed inside maps of
2516 *                types **BPF_MAP_TYPE_HASH** and **BPF_MAP_TYPE_ARRAY** (this
2517 *                list could be extended in the future).
2518 *              * BTF description of the map is mandatory.
2519 *              * The BPF program can take ONE lock at a time, since taking two
2520 *                or more could cause dead locks.
2521 *              * Only one **struct bpf_spin_lock** is allowed per map element.
2522 *              * When the lock is taken, calls (either BPF to BPF or helpers)
2523 *                are not allowed.
2524 *              * The **BPF_LD_ABS** and **BPF_LD_IND** instructions are not
2525 *                allowed inside a spinlock-ed region.
2526 *              * The BPF program MUST call **bpf_spin_unlock**\ () to release
2527 *                the lock, on all execution paths, before it returns.
2528 *              * The BPF program can access **struct bpf_spin_lock** only via
2529 *                the **bpf_spin_lock**\ () and **bpf_spin_unlock**\ ()
2530 *                helpers. Loading or storing data into the **struct
2531 *                bpf_spin_lock** *lock*\ **;** field of a map is not allowed.
2532 *              * To use the **bpf_spin_lock**\ () helper, the BTF description
2533 *                of the map value must be a struct and have **struct
2534 *                bpf_spin_lock** *anyname*\ **;** field at the top level.
2535 *                Nested lock inside another struct is not allowed.
2536 *              * The **struct bpf_spin_lock** *lock* field in a map value must
2537 *                be aligned on a multiple of 4 bytes in that value.
2538 *              * Syscall with command **BPF_MAP_LOOKUP_ELEM** does not copy
2539 *                the **bpf_spin_lock** field to user space.
2540 *              * Syscall with command **BPF_MAP_UPDATE_ELEM**, or update from
2541 *                a BPF program, do not update the **bpf_spin_lock** field.
2542 *              * **bpf_spin_lock** cannot be on the stack or inside a
2543 *                networking packet (it can only be inside of a map values).
2544 *              * **bpf_spin_lock** is available to root only.
2545 *              * Tracing programs and socket filter programs cannot use
2546 *                **bpf_spin_lock**\ () due to insufficient preemption checks
2547 *                (but this may change in the future).
2548 *              * **bpf_spin_lock** is not allowed in inner maps of map-in-map.
2549 *      Return
2550 *              0
2551 *
2552 * int bpf_spin_unlock(struct bpf_spin_lock *lock)
2553 *      Description
2554 *              Release the *lock* previously locked by a call to
2555 *              **bpf_spin_lock**\ (\ *lock*\ ).
2556 *      Return
2557 *              0
2558 *
2559 * struct bpf_sock *bpf_sk_fullsock(struct bpf_sock *sk)
2560 *      Description
2561 *              This helper gets a **struct bpf_sock** pointer such
2562 *              that all the fields in this **bpf_sock** can be accessed.
2563 *      Return
2564 *              A **struct bpf_sock** pointer on success, or **NULL** in
2565 *              case of failure.
2566 *
2567 * struct bpf_tcp_sock *bpf_tcp_sock(struct bpf_sock *sk)
2568 *      Description
2569 *              This helper gets a **struct bpf_tcp_sock** pointer from a
2570 *              **struct bpf_sock** pointer.
2571 *      Return
2572 *              A **struct bpf_tcp_sock** pointer on success, or **NULL** in
2573 *              case of failure.
2574 *
2575 * int bpf_skb_ecn_set_ce(struct sk_buff *skb)
2576 *      Description
2577 *              Set ECN (Explicit Congestion Notification) field of IP header
2578 *              to **CE** (Congestion Encountered) if current value is **ECT**
2579 *              (ECN Capable Transport). Otherwise, do nothing. Works with IPv6
2580 *              and IPv4.
2581 *      Return
2582 *              1 if the **CE** flag is set (either by the current helper call
2583 *              or because it was already present), 0 if it is not set.
2584 *
2585 * struct bpf_sock *bpf_get_listener_sock(struct bpf_sock *sk)
2586 *      Description
2587 *              Return a **struct bpf_sock** pointer in **TCP_LISTEN** state.
2588 *              **bpf_sk_release**\ () is unnecessary and not allowed.
2589 *      Return
2590 *              A **struct bpf_sock** pointer on success, or **NULL** in
2591 *              case of failure.
2592 *
2593 * struct bpf_sock *bpf_skc_lookup_tcp(void *ctx, struct bpf_sock_tuple *tuple, u32 tuple_size, u64 netns, u64 flags)
2594 *      Description
2595 *              Look for TCP socket matching *tuple*, optionally in a child
2596 *              network namespace *netns*. The return value must be checked,
2597 *              and if non-**NULL**, released via **bpf_sk_release**\ ().
2598 *
2599 *              This function is identical to **bpf_sk_lookup_tcp**\ (), except
2600 *              that it also returns timewait or request sockets. Use
2601 *              **bpf_sk_fullsock**\ () or **bpf_tcp_sock**\ () to access the
2602 *              full structure.
2603 *
2604 *              This helper is available only if the kernel was compiled with
2605 *              **CONFIG_NET** configuration option.
2606 *      Return
2607 *              Pointer to **struct bpf_sock**, or **NULL** in case of failure.
2608 *              For sockets with reuseport option, the **struct bpf_sock**
2609 *              result is from *reuse*\ **->socks**\ [] using the hash of the
2610 *              tuple.
2611 *
2612 * int bpf_tcp_check_syncookie(struct bpf_sock *sk, void *iph, u32 iph_len, struct tcphdr *th, u32 th_len)
2613 *      Description
2614 *              Check whether *iph* and *th* contain a valid SYN cookie ACK for
2615 *              the listening socket in *sk*.
2616 *
2617 *              *iph* points to the start of the IPv4 or IPv6 header, while
2618 *              *iph_len* contains **sizeof**\ (**struct iphdr**) or
2619 *              **sizeof**\ (**struct ip6hdr**).
2620 *
2621 *              *th* points to the start of the TCP header, while *th_len*
2622 *              contains **sizeof**\ (**struct tcphdr**).
2623 *
2624 *      Return
2625 *              0 if *iph* and *th* are a valid SYN cookie ACK, or a negative
2626 *              error otherwise.
2627 *
2628 * int bpf_sysctl_get_name(struct bpf_sysctl *ctx, char *buf, size_t buf_len, u64 flags)
2629 *      Description
2630 *              Get name of sysctl in /proc/sys/ and copy it into provided by
2631 *              program buffer *buf* of size *buf_len*.
2632 *
2633 *              The buffer is always NUL terminated, unless it's zero-sized.
2634 *
2635 *              If *flags* is zero, full name (e.g. "net/ipv4/tcp_mem") is
2636 *              copied. Use **BPF_F_SYSCTL_BASE_NAME** flag to copy base name
2637 *              only (e.g. "tcp_mem").
2638 *      Return
2639 *              Number of character copied (not including the trailing NUL).
2640 *
2641 *              **-E2BIG** if the buffer wasn't big enough (*buf* will contain
2642 *              truncated name in this case).
2643 *
2644 * int bpf_sysctl_get_current_value(struct bpf_sysctl *ctx, char *buf, size_t buf_len)
2645 *      Description
2646 *              Get current value of sysctl as it is presented in /proc/sys
2647 *              (incl. newline, etc), and copy it as a string into provided
2648 *              by program buffer *buf* of size *buf_len*.
2649 *
2650 *              The whole value is copied, no matter what file position user
2651 *              space issued e.g. sys_read at.
2652 *
2653 *              The buffer is always NUL terminated, unless it's zero-sized.
2654 *      Return
2655 *              Number of character copied (not including the trailing NUL).
2656 *
2657 *              **-E2BIG** if the buffer wasn't big enough (*buf* will contain
2658 *              truncated name in this case).
2659 *
2660 *              **-EINVAL** if current value was unavailable, e.g. because
2661 *              sysctl is uninitialized and read returns -EIO for it.
2662 *
2663 * int bpf_sysctl_get_new_value(struct bpf_sysctl *ctx, char *buf, size_t buf_len)
2664 *      Description
2665 *              Get new value being written by user space to sysctl (before
2666 *              the actual write happens) and copy it as a string into
2667 *              provided by program buffer *buf* of size *buf_len*.
2668 *
2669 *              User space may write new value at file position > 0.
2670 *
2671 *              The buffer is always NUL terminated, unless it's zero-sized.
2672 *      Return
2673 *              Number of character copied (not including the trailing NUL).
2674 *
2675 *              **-E2BIG** if the buffer wasn't big enough (*buf* will contain
2676 *              truncated name in this case).
2677 *
2678 *              **-EINVAL** if sysctl is being read.
2679 *
2680 * int bpf_sysctl_set_new_value(struct bpf_sysctl *ctx, const char *buf, size_t buf_len)
2681 *      Description
2682 *              Override new value being written by user space to sysctl with
2683 *              value provided by program in buffer *buf* of size *buf_len*.
2684 *
2685 *              *buf* should contain a string in same form as provided by user
2686 *              space on sysctl write.
2687 *
2688 *              User space may write new value at file position > 0. To override
2689 *              the whole sysctl value file position should be set to zero.
2690 *      Return
2691 *              0 on success.
2692 *
2693 *              **-E2BIG** if the *buf_len* is too big.
2694 *
2695 *              **-EINVAL** if sysctl is being read.
2696 *
2697 * int bpf_strtol(const char *buf, size_t buf_len, u64 flags, long *res)
2698 *      Description
2699 *              Convert the initial part of the string from buffer *buf* of
2700 *              size *buf_len* to a long integer according to the given base
2701 *              and save the result in *res*.
2702 *
2703 *              The string may begin with an arbitrary amount of white space
2704 *              (as determined by **isspace**\ (3)) followed by a single
2705 *              optional '**-**' sign.
2706 *
2707 *              Five least significant bits of *flags* encode base, other bits
2708 *              are currently unused.
2709 *
2710 *              Base must be either 8, 10, 16 or 0 to detect it automatically
2711 *              similar to user space **strtol**\ (3).
2712 *      Return
2713 *              Number of characters consumed on success. Must be positive but
2714 *              no more than *buf_len*.
2715 *
2716 *              **-EINVAL** if no valid digits were found or unsupported base
2717 *              was provided.
2718 *
2719 *              **-ERANGE** if resulting value was out of range.
2720 *
2721 * int bpf_strtoul(const char *buf, size_t buf_len, u64 flags, unsigned long *res)
2722 *      Description
2723 *              Convert the initial part of the string from buffer *buf* of
2724 *              size *buf_len* to an unsigned long integer according to the
2725 *              given base and save the result in *res*.
2726 *
2727 *              The string may begin with an arbitrary amount of white space
2728 *              (as determined by **isspace**\ (3)).
2729 *
2730 *              Five least significant bits of *flags* encode base, other bits
2731 *              are currently unused.
2732 *
2733 *              Base must be either 8, 10, 16 or 0 to detect it automatically
2734 *              similar to user space **strtoul**\ (3).
2735 *      Return
2736 *              Number of characters consumed on success. Must be positive but
2737 *              no more than *buf_len*.
2738 *
2739 *              **-EINVAL** if no valid digits were found or unsupported base
2740 *              was provided.
2741 *
2742 *              **-ERANGE** if resulting value was out of range.
2743 *
2744 * void *bpf_sk_storage_get(struct bpf_map *map, struct bpf_sock *sk, void *value, u64 flags)
2745 *      Description
2746 *              Get a bpf-local-storage from a *sk*.
2747 *
2748 *              Logically, it could be thought of getting the value from
2749 *              a *map* with *sk* as the **key**.  From this
2750 *              perspective,  the usage is not much different from
2751 *              **bpf_map_lookup_elem**\ (*map*, **&**\ *sk*) except this
2752 *              helper enforces the key must be a full socket and the map must
2753 *              be a **BPF_MAP_TYPE_SK_STORAGE** also.
2754 *
2755 *              Underneath, the value is stored locally at *sk* instead of
2756 *              the *map*.  The *map* is used as the bpf-local-storage
2757 *              "type". The bpf-local-storage "type" (i.e. the *map*) is
2758 *              searched against all bpf-local-storages residing at *sk*.
2759 *
2760 *              An optional *flags* (**BPF_SK_STORAGE_GET_F_CREATE**) can be
2761 *              used such that a new bpf-local-storage will be
2762 *              created if one does not exist.  *value* can be used
2763 *              together with **BPF_SK_STORAGE_GET_F_CREATE** to specify
2764 *              the initial value of a bpf-local-storage.  If *value* is
2765 *              **NULL**, the new bpf-local-storage will be zero initialized.
2766 *      Return
2767 *              A bpf-local-storage pointer is returned on success.
2768 *
2769 *              **NULL** if not found or there was an error in adding
2770 *              a new bpf-local-storage.
2771 *
2772 * int bpf_sk_storage_delete(struct bpf_map *map, struct bpf_sock *sk)
2773 *      Description
2774 *              Delete a bpf-local-storage from a *sk*.
2775 *      Return
2776 *              0 on success.
2777 *
2778 *              **-ENOENT** if the bpf-local-storage cannot be found.
2779 *
2780 * int bpf_send_signal(u32 sig)
2781 *      Description
2782 *              Send signal *sig* to the process of the current task.
2783 *              The signal may be delivered to any of this process's threads.
2784 *      Return
2785 *              0 on success or successfully queued.
2786 *
2787 *              **-EBUSY** if work queue under nmi is full.
2788 *
2789 *              **-EINVAL** if *sig* is invalid.
2790 *
2791 *              **-EPERM** if no permission to send the *sig*.
2792 *
2793 *              **-EAGAIN** if bpf program can try again.
2794 *
2795 * s64 bpf_tcp_gen_syncookie(struct bpf_sock *sk, void *iph, u32 iph_len, struct tcphdr *th, u32 th_len)
2796 *      Description
2797 *              Try to issue a SYN cookie for the packet with corresponding
2798 *              IP/TCP headers, *iph* and *th*, on the listening socket in *sk*.
2799 *
2800 *              *iph* points to the start of the IPv4 or IPv6 header, while
2801 *              *iph_len* contains **sizeof**\ (**struct iphdr**) or
2802 *              **sizeof**\ (**struct ip6hdr**).
2803 *
2804 *              *th* points to the start of the TCP header, while *th_len*
2805 *              contains the length of the TCP header.
2806 *
2807 *      Return
2808 *              On success, lower 32 bits hold the generated SYN cookie in
2809 *              followed by 16 bits which hold the MSS value for that cookie,
2810 *              and the top 16 bits are unused.
2811 *
2812 *              On failure, the returned value is one of the following:
2813 *
2814 *              **-EINVAL** SYN cookie cannot be issued due to error
2815 *
2816 *              **-ENOENT** SYN cookie should not be issued (no SYN flood)
2817 *
2818 *              **-EOPNOTSUPP** kernel configuration does not enable SYN cookies
2819 *
2820 *              **-EPROTONOSUPPORT** IP packet version is not 4 or 6
2821 *
2822 * int bpf_skb_output(void *ctx, struct bpf_map *map, u64 flags, void *data, u64 size)
2823 *      Description
2824 *              Write raw *data* blob into a special BPF perf event held by
2825 *              *map* of type **BPF_MAP_TYPE_PERF_EVENT_ARRAY**. This perf
2826 *              event must have the following attributes: **PERF_SAMPLE_RAW**
2827 *              as **sample_type**, **PERF_TYPE_SOFTWARE** as **type**, and
2828 *              **PERF_COUNT_SW_BPF_OUTPUT** as **config**.
2829 *
2830 *              The *flags* are used to indicate the index in *map* for which
2831 *              the value must be put, masked with **BPF_F_INDEX_MASK**.
2832 *              Alternatively, *flags* can be set to **BPF_F_CURRENT_CPU**
2833 *              to indicate that the index of the current CPU core should be
2834 *              used.
2835 *
2836 *              The value to write, of *size*, is passed through eBPF stack and
2837 *              pointed by *data*.
2838 *
2839 *              *ctx* is a pointer to in-kernel struct sk_buff.
2840 *
2841 *              This helper is similar to **bpf_perf_event_output**\ () but
2842 *              restricted to raw_tracepoint bpf programs.
2843 *      Return
2844 *              0 on success, or a negative error in case of failure.
2845 *
2846 * int bpf_probe_read_user(void *dst, u32 size, const void *unsafe_ptr)
2847 *      Description
2848 *              Safely attempt to read *size* bytes from user space address
2849 *              *unsafe_ptr* and store the data in *dst*.
2850 *      Return
2851 *              0 on success, or a negative error in case of failure.
2852 *
2853 * int bpf_probe_read_kernel(void *dst, u32 size, const void *unsafe_ptr)
2854 *      Description
2855 *              Safely attempt to read *size* bytes from kernel space address
2856 *              *unsafe_ptr* and store the data in *dst*.
2857 *      Return
2858 *              0 on success, or a negative error in case of failure.
2859 *
2860 * int bpf_probe_read_user_str(void *dst, u32 size, const void *unsafe_ptr)
2861 *      Description
2862 *              Copy a NUL terminated string from an unsafe user address
2863 *              *unsafe_ptr* to *dst*. The *size* should include the
2864 *              terminating NUL byte. In case the string length is smaller than
2865 *              *size*, the target is not padded with further NUL bytes. If the
2866 *              string length is larger than *size*, just *size*-1 bytes are
2867 *              copied and the last byte is set to NUL.
2868 *
2869 *              On success, the length of the copied string is returned. This
2870 *              makes this helper useful in tracing programs for reading
2871 *              strings, and more importantly to get its length at runtime. See
2872 *              the following snippet:
2873 *
2874 *              ::
2875 *
2876 *                      SEC("kprobe/sys_open")
2877 *                      void bpf_sys_open(struct pt_regs *ctx)
2878 *                      {
2879 *                              char buf[PATHLEN]; // PATHLEN is defined to 256
2880 *                              int res = bpf_probe_read_user_str(buf, sizeof(buf),
2881 *                                                                ctx->di);
2882 *
2883 *                              // Consume buf, for example push it to
2884 *                              // userspace via bpf_perf_event_output(); we
2885 *                              // can use res (the string length) as event
2886 *                              // size, after checking its boundaries.
2887 *                      }
2888 *
2889 *              In comparison, using **bpf_probe_read_user()** helper here
2890 *              instead to read the string would require to estimate the length
2891 *              at compile time, and would often result in copying more memory
2892 *              than necessary.
2893 *
2894 *              Another useful use case is when parsing individual process
2895 *              arguments or individual environment variables navigating
2896 *              *current*\ **->mm->arg_start** and *current*\
2897 *              **->mm->env_start**: using this helper and the return value,
2898 *              one can quickly iterate at the right offset of the memory area.
2899 *      Return
2900 *              On success, the strictly positive length of the string,
2901 *              including the trailing NUL character. On error, a negative
2902 *              value.
2903 *
2904 * int bpf_probe_read_kernel_str(void *dst, u32 size, const void *unsafe_ptr)
2905 *      Description
2906 *              Copy a NUL terminated string from an unsafe kernel address *unsafe_ptr*
2907 *              to *dst*. Same semantics as with bpf_probe_read_user_str() apply.
2908 *      Return
2909 *              On success, the strictly positive length of the string, including
2910 *              the trailing NUL character. On error, a negative value.
2911 *
2912 * int bpf_tcp_send_ack(void *tp, u32 rcv_nxt)
2913 *      Description
2914 *              Send out a tcp-ack. *tp* is the in-kernel struct tcp_sock.
2915 *              *rcv_nxt* is the ack_seq to be sent out.
2916 *      Return
2917 *              0 on success, or a negative error in case of failure.
2918 *
2919 * int bpf_send_signal_thread(u32 sig)
2920 *      Description
2921 *              Send signal *sig* to the thread corresponding to the current task.
2922 *      Return
2923 *              0 on success or successfully queued.
2924 *
2925 *              **-EBUSY** if work queue under nmi is full.
2926 *
2927 *              **-EINVAL** if *sig* is invalid.
2928 *
2929 *              **-EPERM** if no permission to send the *sig*.
2930 *
2931 *              **-EAGAIN** if bpf program can try again.
2932 *
2933 * u64 bpf_jiffies64(void)
2934 *      Description
2935 *              Obtain the 64bit jiffies
2936 *      Return
2937 *              The 64 bit jiffies
2938 *
2939 * int bpf_read_branch_records(struct bpf_perf_event_data *ctx, void *buf, u32 size, u64 flags)
2940 *      Description
2941 *              For an eBPF program attached to a perf event, retrieve the
2942 *              branch records (struct perf_branch_entry) associated to *ctx*
2943 *              and store it in the buffer pointed by *buf* up to size
2944 *              *size* bytes.
2945 *      Return
2946 *              On success, number of bytes written to *buf*. On error, a
2947 *              negative value.
2948 *
2949 *              The *flags* can be set to **BPF_F_GET_BRANCH_RECORDS_SIZE** to
2950 *              instead return the number of bytes required to store all the
2951 *              branch entries. If this flag is set, *buf* may be NULL.
2952 *
2953 *              **-EINVAL** if arguments invalid or **size** not a multiple
2954 *              of sizeof(struct perf_branch_entry).
2955 *
2956 *              **-ENOENT** if architecture does not support branch records.
2957 *
2958 * int bpf_get_ns_current_pid_tgid(u64 dev, u64 ino, struct bpf_pidns_info *nsdata, u32 size)
2959 *      Description
2960 *              Returns 0 on success, values for *pid* and *tgid* as seen from the current
2961 *              *namespace* will be returned in *nsdata*.
2962 *
2963 *              On failure, the returned value is one of the following:
2964 *
2965 *              **-EINVAL** if dev and inum supplied don't match dev_t and inode number
2966 *              with nsfs of current task, or if dev conversion to dev_t lost high bits.
2967 *
2968 *              **-ENOENT** if pidns does not exists for the current task.
2969 *
2970 * int bpf_xdp_output(void *ctx, struct bpf_map *map, u64 flags, void *data, u64 size)
2971 *      Description
2972 *              Write raw *data* blob into a special BPF perf event held by
2973 *              *map* of type **BPF_MAP_TYPE_PERF_EVENT_ARRAY**. This perf
2974 *              event must have the following attributes: **PERF_SAMPLE_RAW**
2975 *              as **sample_type**, **PERF_TYPE_SOFTWARE** as **type**, and
2976 *              **PERF_COUNT_SW_BPF_OUTPUT** as **config**.
2977 *
2978 *              The *flags* are used to indicate the index in *map* for which
2979 *              the value must be put, masked with **BPF_F_INDEX_MASK**.
2980 *              Alternatively, *flags* can be set to **BPF_F_CURRENT_CPU**
2981 *              to indicate that the index of the current CPU core should be
2982 *              used.
2983 *
2984 *              The value to write, of *size*, is passed through eBPF stack and
2985 *              pointed by *data*.
2986 *
2987 *              *ctx* is a pointer to in-kernel struct xdp_buff.
2988 *
2989 *              This helper is similar to **bpf_perf_eventoutput**\ () but
2990 *              restricted to raw_tracepoint bpf programs.
2991 *      Return
2992 *              0 on success, or a negative error in case of failure.
2993 *
2994 * u64 bpf_get_netns_cookie(void *ctx)
2995 *      Description
2996 *              Retrieve the cookie (generated by the kernel) of the network
2997 *              namespace the input *ctx* is associated with. The network
2998 *              namespace cookie remains stable for its lifetime and provides
2999 *              a global identifier that can be assumed unique. If *ctx* is
3000 *              NULL, then the helper returns the cookie for the initial
3001 *              network namespace. The cookie itself is very similar to that
3002 *              of bpf_get_socket_cookie() helper, but for network namespaces
3003 *              instead of sockets.
3004 *      Return
3005 *              A 8-byte long opaque number.
3006 *
3007 * u64 bpf_get_current_ancestor_cgroup_id(int ancestor_level)
3008 *      Description
3009 *              Return id of cgroup v2 that is ancestor of the cgroup associated
3010 *              with the current task at the *ancestor_level*. The root cgroup
3011 *              is at *ancestor_level* zero and each step down the hierarchy
3012 *              increments the level. If *ancestor_level* == level of cgroup
3013 *              associated with the current task, then return value will be the
3014 *              same as that of **bpf_get_current_cgroup_id**\ ().
3015 *
3016 *              The helper is useful to implement policies based on cgroups
3017 *              that are upper in hierarchy than immediate cgroup associated
3018 *              with the current task.
3019 *
3020 *              The format of returned id and helper limitations are same as in
3021 *              **bpf_get_current_cgroup_id**\ ().
3022 *      Return
3023 *              The id is returned or 0 in case the id could not be retrieved.
3024 *
3025 * int bpf_sk_assign(struct sk_buff *skb, struct bpf_sock *sk, u64 flags)
3026 *      Description
3027 *              Assign the *sk* to the *skb*. When combined with appropriate
3028 *              routing configuration to receive the packet towards the socket,
3029 *              will cause *skb* to be delivered to the specified socket.
3030 *              Subsequent redirection of *skb* via  **bpf_redirect**\ (),
3031 *              **bpf_clone_redirect**\ () or other methods outside of BPF may
3032 *              interfere with successful delivery to the socket.
3033 *
3034 *              This operation is only valid from TC ingress path.
3035 *
3036 *              The *flags* argument must be zero.
3037 *      Return
3038 *              0 on success, or a negative errno in case of failure.
3039 *
3040 *              * **-EINVAL**           Unsupported flags specified.
3041 *              * **-ENOENT**           Socket is unavailable for assignment.
3042 *              * **-ENETUNREACH**      Socket is unreachable (wrong netns).
3043 *              * **-EOPNOTSUPP**       Unsupported operation, for example a
3044 *                                      call from outside of TC ingress.
3045 *              * **-ESOCKTNOSUPPORT**  Socket type not supported (reuseport).
3046 */
3047#define __BPF_FUNC_MAPPER(FN)           \
3048        FN(unspec),                     \
3049        FN(map_lookup_elem),            \
3050        FN(map_update_elem),            \
3051        FN(map_delete_elem),            \
3052        FN(probe_read),                 \
3053        FN(ktime_get_ns),               \
3054        FN(trace_printk),               \
3055        FN(get_prandom_u32),            \
3056        FN(get_smp_processor_id),       \
3057        FN(skb_store_bytes),            \
3058        FN(l3_csum_replace),            \
3059        FN(l4_csum_replace),            \
3060        FN(tail_call),                  \
3061        FN(clone_redirect),             \
3062        FN(get_current_pid_tgid),       \
3063        FN(get_current_uid_gid),        \
3064        FN(get_current_comm),           \
3065        FN(get_cgroup_classid),         \
3066        FN(skb_vlan_push),              \
3067        FN(skb_vlan_pop),               \
3068        FN(skb_get_tunnel_key),         \
3069        FN(skb_set_tunnel_key),         \
3070        FN(perf_event_read),            \
3071        FN(redirect),                   \
3072        FN(get_route_realm),            \
3073        FN(perf_event_output),          \
3074        FN(skb_load_bytes),             \
3075        FN(get_stackid),                \
3076        FN(csum_diff),                  \
3077        FN(skb_get_tunnel_opt),         \
3078        FN(skb_set_tunnel_opt),         \
3079        FN(skb_change_proto),           \
3080        FN(skb_change_type),            \
3081        FN(skb_under_cgroup),           \
3082        FN(get_hash_recalc),            \
3083        FN(get_current_task),           \
3084        FN(probe_write_user),           \
3085        FN(current_task_under_cgroup),  \
3086        FN(skb_change_tail),            \
3087        FN(skb_pull_data),              \
3088        FN(csum_update),                \
3089        FN(set_hash_invalid),           \
3090        FN(get_numa_node_id),           \
3091        FN(skb_change_head),            \
3092        FN(xdp_adjust_head),            \
3093        FN(probe_read_str),             \
3094        FN(get_socket_cookie),          \
3095        FN(get_socket_uid),             \
3096        FN(set_hash),                   \
3097        FN(setsockopt),                 \
3098        FN(skb_adjust_room),            \
3099        FN(redirect_map),               \
3100        FN(sk_redirect_map),            \
3101        FN(sock_map_update),            \
3102        FN(xdp_adjust_meta),            \
3103        FN(perf_event_read_value),      \
3104        FN(perf_prog_read_value),       \
3105        FN(getsockopt),                 \
3106        FN(override_return),            \
3107        FN(sock_ops_cb_flags_set),      \
3108        FN(msg_redirect_map),           \
3109        FN(msg_apply_bytes),            \
3110        FN(msg_cork_bytes),             \
3111        FN(msg_pull_data),              \
3112        FN(bind),                       \
3113        FN(xdp_adjust_tail),            \
3114        FN(skb_get_xfrm_state),         \
3115        FN(get_stack),                  \
3116        FN(skb_load_bytes_relative),    \
3117        FN(fib_lookup),                 \
3118        FN(sock_hash_update),           \
3119        FN(msg_redirect_hash),          \
3120        FN(sk_redirect_hash),           \
3121        FN(lwt_push_encap),             \
3122        FN(lwt_seg6_store_bytes),       \
3123        FN(lwt_seg6_adjust_srh),        \
3124        FN(lwt_seg6_action),            \
3125        FN(rc_repeat),                  \
3126        FN(rc_keydown),                 \
3127        FN(skb_cgroup_id),              \
3128        FN(get_current_cgroup_id),      \
3129        FN(get_local_storage),          \
3130        FN(sk_select_reuseport),        \
3131        FN(skb_ancestor_cgroup_id),     \
3132        FN(sk_lookup_tcp),              \
3133        FN(sk_lookup_udp),              \
3134        FN(sk_release),                 \
3135        FN(map_push_elem),              \
3136        FN(map_pop_elem),               \
3137        FN(map_peek_elem),              \
3138        FN(msg_push_data),              \
3139        FN(msg_pop_data),               \
3140        FN(rc_pointer_rel),             \
3141        FN(spin_lock),                  \
3142        FN(spin_unlock),                \
3143        FN(sk_fullsock),                \
3144        FN(tcp_sock),                   \
3145        FN(skb_ecn_set_ce),             \
3146        FN(get_listener_sock),          \
3147        FN(skc_lookup_tcp),             \
3148        FN(tcp_check_syncookie),        \
3149        FN(sysctl_get_name),            \
3150        FN(sysctl_get_current_value),   \
3151        FN(sysctl_get_new_value),       \
3152        FN(sysctl_set_new_value),       \
3153        FN(strtol),                     \
3154        FN(strtoul),                    \
3155        FN(sk_storage_get),             \
3156        FN(sk_storage_delete),          \
3157        FN(send_signal),                \
3158        FN(tcp_gen_syncookie),          \
3159        FN(skb_output),                 \
3160        FN(probe_read_user),            \
3161        FN(probe_read_kernel),          \
3162        FN(probe_read_user_str),        \
3163        FN(probe_read_kernel_str),      \
3164        FN(tcp_send_ack),               \
3165        FN(send_signal_thread),         \
3166        FN(jiffies64),                  \
3167        FN(read_branch_records),        \
3168        FN(get_ns_current_pid_tgid),    \
3169        FN(xdp_output),                 \
3170        FN(get_netns_cookie),           \
3171        FN(get_current_ancestor_cgroup_id),     \
3172        FN(sk_assign),
3173
3174/* integer value in 'imm' field of BPF_CALL instruction selects which helper
3175 * function eBPF program intends to call
3176 */
3177#define __BPF_ENUM_FN(x) BPF_FUNC_ ## x
3178enum bpf_func_id {
3179        __BPF_FUNC_MAPPER(__BPF_ENUM_FN)
3180        __BPF_FUNC_MAX_ID,
3181};
3182#undef __BPF_ENUM_FN
3183
3184/* All flags used by eBPF helper functions, placed here. */
3185
3186/* BPF_FUNC_skb_store_bytes flags. */
3187enum {
3188        BPF_F_RECOMPUTE_CSUM            = (1ULL << 0),
3189        BPF_F_INVALIDATE_HASH           = (1ULL << 1),
3190};
3191
3192/* BPF_FUNC_l3_csum_replace and BPF_FUNC_l4_csum_replace flags.
3193 * First 4 bits are for passing the header field size.
3194 */
3195enum {
3196        BPF_F_HDR_FIELD_MASK            = 0xfULL,
3197};
3198
3199/* BPF_FUNC_l4_csum_replace flags. */
3200enum {
3201        BPF_F_PSEUDO_HDR                = (1ULL << 4),
3202        BPF_F_MARK_MANGLED_0            = (1ULL << 5),
3203        BPF_F_MARK_ENFORCE              = (1ULL << 6),
3204};
3205
3206/* BPF_FUNC_clone_redirect and BPF_FUNC_redirect flags. */
3207enum {
3208        BPF_F_INGRESS                   = (1ULL << 0),
3209};
3210
3211/* BPF_FUNC_skb_set_tunnel_key and BPF_FUNC_skb_get_tunnel_key flags. */
3212enum {
3213        BPF_F_TUNINFO_IPV6              = (1ULL << 0),
3214};
3215
3216/* flags for both BPF_FUNC_get_stackid and BPF_FUNC_get_stack. */
3217enum {
3218        BPF_F_SKIP_FIELD_MASK           = 0xffULL,
3219        BPF_F_USER_STACK                = (1ULL << 8),
3220/* flags used by BPF_FUNC_get_stackid only. */
3221        BPF_F_FAST_STACK_CMP            = (1ULL << 9),
3222        BPF_F_REUSE_STACKID             = (1ULL << 10),
3223/* flags used by BPF_FUNC_get_stack only. */
3224        BPF_F_USER_BUILD_ID             = (1ULL << 11),
3225};
3226
3227/* BPF_FUNC_skb_set_tunnel_key flags. */
3228enum {
3229        BPF_F_ZERO_CSUM_TX              = (1ULL << 1),
3230        BPF_F_DONT_FRAGMENT             = (1ULL << 2),
3231        BPF_F_SEQ_NUMBER                = (1ULL << 3),
3232};
3233
3234/* BPF_FUNC_perf_event_output, BPF_FUNC_perf_event_read and
3235 * BPF_FUNC_perf_event_read_value flags.
3236 */
3237enum {
3238        BPF_F_INDEX_MASK                = 0xffffffffULL,
3239        BPF_F_CURRENT_CPU               = BPF_F_INDEX_MASK,
3240/* BPF_FUNC_perf_event_output for sk_buff input context. */
3241        BPF_F_CTXLEN_MASK               = (0xfffffULL << 32),
3242};
3243
3244/* Current network namespace */
3245enum {
3246        BPF_F_CURRENT_NETNS             = (-1L),
3247};
3248
3249/* BPF_FUNC_skb_adjust_room flags. */
3250enum {
3251        BPF_F_ADJ_ROOM_FIXED_GSO        = (1ULL << 0),
3252        BPF_F_ADJ_ROOM_ENCAP_L3_IPV4    = (1ULL << 1),
3253        BPF_F_ADJ_ROOM_ENCAP_L3_IPV6    = (1ULL << 2),
3254        BPF_F_ADJ_ROOM_ENCAP_L4_GRE     = (1ULL << 3),
3255        BPF_F_ADJ_ROOM_ENCAP_L4_UDP     = (1ULL << 4),
3256};
3257
3258enum {
3259        BPF_ADJ_ROOM_ENCAP_L2_MASK      = 0xff,
3260        BPF_ADJ_ROOM_ENCAP_L2_SHIFT     = 56,
3261};
3262
3263#define BPF_F_ADJ_ROOM_ENCAP_L2(len)    (((__u64)len & \
3264                                          BPF_ADJ_ROOM_ENCAP_L2_MASK) \
3265                                         << BPF_ADJ_ROOM_ENCAP_L2_SHIFT)
3266
3267/* BPF_FUNC_sysctl_get_name flags. */
3268enum {
3269        BPF_F_SYSCTL_BASE_NAME          = (1ULL << 0),
3270};
3271
3272/* BPF_FUNC_sk_storage_get flags */
3273enum {
3274        BPF_SK_STORAGE_GET_F_CREATE     = (1ULL << 0),
3275};
3276
3277/* BPF_FUNC_read_branch_records flags. */
3278enum {
3279        BPF_F_GET_BRANCH_RECORDS_SIZE   = (1ULL << 0),
3280};
3281
3282/* Mode for BPF_FUNC_skb_adjust_room helper. */
3283enum bpf_adj_room_mode {
3284        BPF_ADJ_ROOM_NET,
3285        BPF_ADJ_ROOM_MAC,
3286};
3287
3288/* Mode for BPF_FUNC_skb_load_bytes_relative helper. */
3289enum bpf_hdr_start_off {
3290        BPF_HDR_START_MAC,
3291        BPF_HDR_START_NET,
3292};
3293
3294/* Encapsulation type for BPF_FUNC_lwt_push_encap helper. */
3295enum bpf_lwt_encap_mode {
3296        BPF_LWT_ENCAP_SEG6,
3297        BPF_LWT_ENCAP_SEG6_INLINE,
3298        BPF_LWT_ENCAP_IP,
3299};
3300
3301#define __bpf_md_ptr(type, name)        \
3302union {                                 \
3303        type name;                      \
3304        __u64 :64;                      \
3305} __attribute__((aligned(8)))
3306
3307/* user accessible mirror of in-kernel sk_buff.
3308 * new fields can only be added to the end of this structure
3309 */
3310struct __sk_buff {
3311        __u32 len;
3312        __u32 pkt_type;
3313        __u32 mark;
3314        __u32 queue_mapping;
3315        __u32 protocol;
3316        __u32 vlan_present;
3317        __u32 vlan_tci;
3318        __u32 vlan_proto;
3319        __u32 priority;
3320        __u32 ingress_ifindex;
3321        __u32 ifindex;
3322        __u32 tc_index;
3323        __u32 cb[5];
3324        __u32 hash;
3325        __u32 tc_classid;
3326        __u32 data;
3327        __u32 data_end;
3328        __u32 napi_id;
3329
3330        /* Accessed by BPF_PROG_TYPE_sk_skb types from here to ... */
3331        __u32 family;
3332        __u32 remote_ip4;       /* Stored in network byte order */
3333        __u32 local_ip4;        /* Stored in network byte order */
3334        __u32 remote_ip6[4];    /* Stored in network byte order */
3335        __u32 local_ip6[4];     /* Stored in network byte order */
3336        __u32 remote_port;      /* Stored in network byte order */
3337        __u32 local_port;       /* stored in host byte order */
3338        /* ... here. */
3339
3340        __u32 data_meta;
3341        __bpf_md_ptr(struct bpf_flow_keys *, flow_keys);
3342        __u64 tstamp;
3343        __u32 wire_len;
3344        __u32 gso_segs;
3345        __bpf_md_ptr(struct bpf_sock *, sk);
3346        __u32 gso_size;
3347};
3348
3349struct bpf_tunnel_key {
3350        __u32 tunnel_id;
3351        union {
3352                __u32 remote_ipv4;
3353                __u32 remote_ipv6[4];
3354        };
3355        __u8 tunnel_tos;
3356        __u8 tunnel_ttl;
3357        __u16 tunnel_ext;       /* Padding, future use. */
3358        __u32 tunnel_label;
3359};
3360
3361/* user accessible mirror of in-kernel xfrm_state.
3362 * new fields can only be added to the end of this structure
3363 */
3364struct bpf_xfrm_state {
3365        __u32 reqid;
3366        __u32 spi;      /* Stored in network byte order */
3367        __u16 family;
3368        __u16 ext;      /* Padding, future use. */
3369        union {
3370                __u32 remote_ipv4;      /* Stored in network byte order */
3371                __u32 remote_ipv6[4];   /* Stored in network byte order */
3372        };
3373};
3374
3375/* Generic BPF return codes which all BPF program types may support.
3376 * The values are binary compatible with their TC_ACT_* counter-part to
3377 * provide backwards compatibility with existing SCHED_CLS and SCHED_ACT
3378 * programs.
3379 *
3380 * XDP is handled seprately, see XDP_*.
3381 */
3382enum bpf_ret_code {
3383        BPF_OK = 0,
3384        /* 1 reserved */
3385        BPF_DROP = 2,
3386        /* 3-6 reserved */
3387        BPF_REDIRECT = 7,
3388        /* >127 are reserved for prog type specific return codes.
3389         *
3390         * BPF_LWT_REROUTE: used by BPF_PROG_TYPE_LWT_IN and
3391         *    BPF_PROG_TYPE_LWT_XMIT to indicate that skb had been
3392         *    changed and should be routed based on its new L3 header.
3393         *    (This is an L3 redirect, as opposed to L2 redirect
3394         *    represented by BPF_REDIRECT above).
3395         */
3396        BPF_LWT_REROUTE = 128,
3397};
3398
3399struct bpf_sock {
3400        __u32 bound_dev_if;
3401        __u32 family;
3402        __u32 type;
3403        __u32 protocol;
3404        __u32 mark;
3405        __u32 priority;
3406        /* IP address also allows 1 and 2 bytes access */
3407        __u32 src_ip4;
3408        __u32 src_ip6[4];
3409        __u32 src_port;         /* host byte order */
3410        __u32 dst_port;         /* network byte order */
3411        __u32 dst_ip4;
3412        __u32 dst_ip6[4];
3413        __u32 state;
3414};
3415
3416struct bpf_tcp_sock {
3417        __u32 snd_cwnd;         /* Sending congestion window            */
3418        __u32 srtt_us;          /* smoothed round trip time << 3 in usecs */
3419        __u32 rtt_min;
3420        __u32 snd_ssthresh;     /* Slow start size threshold            */
3421        __u32 rcv_nxt;          /* What we want to receive next         */
3422        __u32 snd_nxt;          /* Next sequence we send                */
3423        __u32 snd_una;          /* First byte we want an ack for        */
3424        __u32 mss_cache;        /* Cached effective mss, not including SACKS */
3425        __u32 ecn_flags;        /* ECN status bits.                     */
3426        __u32 rate_delivered;   /* saved rate sample: packets delivered */
3427        __u32 rate_interval_us; /* saved rate sample: time elapsed */
3428        __u32 packets_out;      /* Packets which are "in flight"        */
3429        __u32 retrans_out;      /* Retransmitted packets out            */
3430        __u32 total_retrans;    /* Total retransmits for entire connection */
3431        __u32 segs_in;          /* RFC4898 tcpEStatsPerfSegsIn
3432                                 * total number of segments in.
3433                                 */
3434        __u32 data_segs_in;     /* RFC4898 tcpEStatsPerfDataSegsIn
3435                                 * total number of data segments in.
3436                                 */
3437        __u32 segs_out;         /* RFC4898 tcpEStatsPerfSegsOut
3438                                 * The total number of segments sent.
3439                                 */
3440        __u32 data_segs_out;    /* RFC4898 tcpEStatsPerfDataSegsOut
3441                                 * total number of data segments sent.
3442                                 */
3443        __u32 lost_out;         /* Lost packets                 */
3444        __u32 sacked_out;       /* SACK'd packets                       */
3445        __u64 bytes_received;   /* RFC4898 tcpEStatsAppHCThruOctetsReceived
3446                                 * sum(delta(rcv_nxt)), or how many bytes
3447                                 * were acked.
3448                                 */
3449        __u64 bytes_acked;      /* RFC4898 tcpEStatsAppHCThruOctetsAcked
3450                                 * sum(delta(snd_una)), or how many bytes
3451                                 * were acked.
3452                                 */
3453        __u32 dsack_dups;       /* RFC4898 tcpEStatsStackDSACKDups
3454                                 * total number of DSACK blocks received
3455                                 */
3456        __u32 delivered;        /* Total data packets delivered incl. rexmits */
3457        __u32 delivered_ce;     /* Like the above but only ECE marked packets */
3458        __u32 icsk_retransmits; /* Number of unrecovered [RTO] timeouts */
3459};
3460
3461struct bpf_sock_tuple {
3462        union {
3463                struct {
3464                        __be32 saddr;
3465                        __be32 daddr;
3466                        __be16 sport;
3467                        __be16 dport;
3468                } ipv4;
3469                struct {
3470                        __be32 saddr[4];
3471                        __be32 daddr[4];
3472                        __be16 sport;
3473                        __be16 dport;
3474                } ipv6;
3475        };
3476};
3477
3478struct bpf_xdp_sock {
3479        __u32 queue_id;
3480};
3481
3482#define XDP_PACKET_HEADROOM 256
3483
3484/* User return codes for XDP prog type.
3485 * A valid XDP program must return one of these defined values. All other
3486 * return codes are reserved for future use. Unknown return codes will
3487 * result in packet drops and a warning via bpf_warn_invalid_xdp_action().
3488 */
3489enum xdp_action {
3490        XDP_ABORTED = 0,
3491        XDP_DROP,
3492        XDP_PASS,
3493        XDP_TX,
3494        XDP_REDIRECT,
3495};
3496
3497/* user accessible metadata for XDP packet hook
3498 * new fields must be added to the end of this structure
3499 */
3500struct xdp_md {
3501        __u32 data;
3502        __u32 data_end;
3503        __u32 data_meta;
3504        /* Below access go through struct xdp_rxq_info */
3505        __u32 ingress_ifindex; /* rxq->dev->ifindex */
3506        __u32 rx_queue_index;  /* rxq->queue_index  */
3507};
3508
3509enum sk_action {
3510        SK_DROP = 0,
3511        SK_PASS,
3512};
3513
3514/* user accessible metadata for SK_MSG packet hook, new fields must
3515 * be added to the end of this structure
3516 */
3517struct sk_msg_md {
3518        __bpf_md_ptr(void *, data);
3519        __bpf_md_ptr(void *, data_end);
3520
3521        __u32 family;
3522        __u32 remote_ip4;       /* Stored in network byte order */
3523        __u32 local_ip4;        /* Stored in network byte order */
3524        __u32 remote_ip6[4];    /* Stored in network byte order */
3525        __u32 local_ip6[4];     /* Stored in network byte order */
3526        __u32 remote_port;      /* Stored in network byte order */
3527        __u32 local_port;       /* stored in host byte order */
3528        __u32 size;             /* Total size of sk_msg */
3529};
3530
3531struct sk_reuseport_md {
3532        /*
3533         * Start of directly accessible data. It begins from
3534         * the tcp/udp header.
3535         */
3536        __bpf_md_ptr(void *, data);
3537        /* End of directly accessible data */
3538        __bpf_md_ptr(void *, data_end);
3539        /*
3540         * Total length of packet (starting from the tcp/udp header).
3541         * Note that the directly accessible bytes (data_end - data)
3542         * could be less than this "len".  Those bytes could be
3543         * indirectly read by a helper "bpf_skb_load_bytes()".
3544         */
3545        __u32 len;
3546        /*
3547         * Eth protocol in the mac header (network byte order). e.g.
3548         * ETH_P_IP(0x0800) and ETH_P_IPV6(0x86DD)
3549         */
3550        __u32 eth_protocol;
3551        __u32 ip_protocol;      /* IP protocol. e.g. IPPROTO_TCP, IPPROTO_UDP */
3552        __u32 bind_inany;       /* Is sock bound to an INANY address? */
3553        __u32 hash;             /* A hash of the packet 4 tuples */
3554};
3555
3556#define BPF_TAG_SIZE    8
3557
3558struct bpf_prog_info {
3559        __u32 type;
3560        __u32 id;
3561        __u8  tag[BPF_TAG_SIZE];
3562        __u32 jited_prog_len;
3563        __u32 xlated_prog_len;
3564        __aligned_u64 jited_prog_insns;
3565        __aligned_u64 xlated_prog_insns;
3566        __u64 load_time;        /* ns since boottime */
3567        __u32 created_by_uid;
3568        __u32 nr_map_ids;
3569        __aligned_u64 map_ids;
3570        char name[BPF_OBJ_NAME_LEN];
3571        __u32 ifindex;
3572        __u32 gpl_compatible:1;
3573        __u32 :31; /* alignment pad */
3574        __u64 netns_dev;
3575        __u64 netns_ino;
3576        __u32 nr_jited_ksyms;
3577        __u32 nr_jited_func_lens;
3578        __aligned_u64 jited_ksyms;
3579        __aligned_u64 jited_func_lens;
3580        __u32 btf_id;
3581        __u32 func_info_rec_size;
3582        __aligned_u64 func_info;
3583        __u32 nr_func_info;
3584        __u32 nr_line_info;
3585        __aligned_u64 line_info;
3586        __aligned_u64 jited_line_info;
3587        __u32 nr_jited_line_info;
3588        __u32 line_info_rec_size;
3589        __u32 jited_line_info_rec_size;
3590        __u32 nr_prog_tags;
3591        __aligned_u64 prog_tags;
3592        __u64 run_time_ns;
3593        __u64 run_cnt;
3594} __attribute__((aligned(8)));
3595
3596struct bpf_map_info {
3597        __u32 type;
3598        __u32 id;
3599        __u32 key_size;
3600        __u32 value_size;
3601        __u32 max_entries;
3602        __u32 map_flags;
3603        char  name[BPF_OBJ_NAME_LEN];
3604        __u32 ifindex;
3605        __u32 btf_vmlinux_value_type_id;
3606        __u64 netns_dev;
3607        __u64 netns_ino;
3608        __u32 btf_id;
3609        __u32 btf_key_type_id;
3610        __u32 btf_value_type_id;
3611} __attribute__((aligned(8)));
3612
3613struct bpf_btf_info {
3614        __aligned_u64 btf;
3615        __u32 btf_size;
3616        __u32 id;
3617} __attribute__((aligned(8)));
3618
3619/* User bpf_sock_addr struct to access socket fields and sockaddr struct passed
3620 * by user and intended to be used by socket (e.g. to bind to, depends on
3621 * attach attach type).
3622 */
3623struct bpf_sock_addr {
3624        __u32 user_family;      /* Allows 4-byte read, but no write. */
3625        __u32 user_ip4;         /* Allows 1,2,4-byte read and 4-byte write.
3626                                 * Stored in network byte order.
3627                                 */
3628        __u32 user_ip6[4];      /* Allows 1,2,4,8-byte read and 4,8-byte write.
3629                                 * Stored in network byte order.
3630                                 */
3631        __u32 user_port;        /* Allows 4-byte read and write.
3632                                 * Stored in network byte order
3633                                 */
3634        __u32 family;           /* Allows 4-byte read, but no write */
3635        __u32 type;             /* Allows 4-byte read, but no write */
3636        __u32 protocol;         /* Allows 4-byte read, but no write */
3637        __u32 msg_src_ip4;      /* Allows 1,2,4-byte read and 4-byte write.
3638                                 * Stored in network byte order.
3639                                 */
3640        __u32 msg_src_ip6[4];   /* Allows 1,2,4,8-byte read and 4,8-byte write.
3641                                 * Stored in network byte order.
3642                                 */
3643        __bpf_md_ptr(struct bpf_sock *, sk);
3644};
3645
3646/* User bpf_sock_ops struct to access socket values and specify request ops
3647 * and their replies.
3648 * Some of this fields are in network (bigendian) byte order and may need
3649 * to be converted before use (bpf_ntohl() defined in samples/bpf/bpf_endian.h).
3650 * New fields can only be added at the end of this structure
3651 */
3652struct bpf_sock_ops {
3653        __u32 op;
3654        union {
3655                __u32 args[4];          /* Optionally passed to bpf program */
3656                __u32 reply;            /* Returned by bpf program          */
3657                __u32 replylong[4];     /* Optionally returned by bpf prog  */
3658        };
3659        __u32 family;
3660        __u32 remote_ip4;       /* Stored in network byte order */
3661        __u32 local_ip4;        /* Stored in network byte order */
3662        __u32 remote_ip6[4];    /* Stored in network byte order */
3663        __u32 local_ip6[4];     /* Stored in network byte order */
3664        __u32 remote_port;      /* Stored in network byte order */
3665        __u32 local_port;       /* stored in host byte order */
3666        __u32 is_fullsock;      /* Some TCP fields are only valid if
3667                                 * there is a full socket. If not, the
3668                                 * fields read as zero.
3669                                 */
3670        __u32 snd_cwnd;
3671        __u32 srtt_us;          /* Averaged RTT << 3 in usecs */
3672        __u32 bpf_sock_ops_cb_flags; /* flags defined in uapi/linux/tcp.h */
3673        __u32 state;
3674        __u32 rtt_min;
3675        __u32 snd_ssthresh;
3676        __u32 rcv_nxt;
3677        __u32 snd_nxt;
3678        __u32 snd_una;
3679        __u32 mss_cache;
3680        __u32 ecn_flags;
3681        __u32 rate_delivered;
3682        __u32 rate_interval_us;
3683        __u32 packets_out;
3684        __u32 retrans_out;
3685        __u32 total_retrans;
3686        __u32 segs_in;
3687        __u32 data_segs_in;
3688        __u32 segs_out;
3689        __u32 data_segs_out;
3690        __u32 lost_out;
3691        __u32 sacked_out;
3692        __u32 sk_txhash;
3693        __u64 bytes_received;
3694        __u64 bytes_acked;
3695        __bpf_md_ptr(struct bpf_sock *, sk);
3696};
3697
3698/* Definitions for bpf_sock_ops_cb_flags */
3699enum {
3700        BPF_SOCK_OPS_RTO_CB_FLAG        = (1<<0),
3701        BPF_SOCK_OPS_RETRANS_CB_FLAG    = (1<<1),
3702        BPF_SOCK_OPS_STATE_CB_FLAG      = (1<<2),
3703        BPF_SOCK_OPS_RTT_CB_FLAG        = (1<<3),
3704/* Mask of all currently supported cb flags */
3705        BPF_SOCK_OPS_ALL_CB_FLAGS       = 0xF,
3706};
3707
3708/* List of known BPF sock_ops operators.
3709 * New entries can only be added at the end
3710 */
3711enum {
3712        BPF_SOCK_OPS_VOID,
3713        BPF_SOCK_OPS_TIMEOUT_INIT,      /* Should return SYN-RTO value to use or
3714                                         * -1 if default value should be used
3715                                         */
3716        BPF_SOCK_OPS_RWND_INIT,         /* Should return initial advertized
3717                                         * window (in packets) or -1 if default
3718                                         * value should be used
3719                                         */
3720        BPF_SOCK_OPS_TCP_CONNECT_CB,    /* Calls BPF program right before an
3721                                         * active connection is initialized
3722                                         */
3723        BPF_SOCK_OPS_ACTIVE_ESTABLISHED_CB,     /* Calls BPF program when an
3724                                                 * active connection is
3725                                                 * established
3726                                                 */
3727        BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB,    /* Calls BPF program when a
3728                                                 * passive connection is
3729                                                 * established
3730                                                 */
3731        BPF_SOCK_OPS_NEEDS_ECN,         /* If connection's congestion control
3732                                         * needs ECN
3733                                         */
3734        BPF_SOCK_OPS_BASE_RTT,          /* Get base RTT. The correct value is
3735                                         * based on the path and may be
3736                                         * dependent on the congestion control
3737                                         * algorithm. In general it indicates
3738                                         * a congestion threshold. RTTs above
3739                                         * this indicate congestion
3740                                         */
3741        BPF_SOCK_OPS_RTO_CB,            /* Called when an RTO has triggered.
3742                                         * Arg1: value of icsk_retransmits
3743                                         * Arg2: value of icsk_rto
3744                                         * Arg3: whether RTO has expired
3745                                         */
3746        BPF_SOCK_OPS_RETRANS_CB,        /* Called when skb is retransmitted.
3747                                         * Arg1: sequence number of 1st byte
3748                                         * Arg2: # segments
3749                                         * Arg3: return value of
3750                                         *       tcp_transmit_skb (0 => success)
3751                                         */
3752        BPF_SOCK_OPS_STATE_CB,          /* Called when TCP changes state.
3753                                         * Arg1: old_state
3754                                         * Arg2: new_state
3755                                         */
3756        BPF_SOCK_OPS_TCP_LISTEN_CB,     /* Called on listen(2), right after
3757                                         * socket transition to LISTEN state.
3758                                         */
3759        BPF_SOCK_OPS_RTT_CB,            /* Called on every RTT.
3760                                         */
3761};
3762
3763/* List of TCP states. There is a build check in net/ipv4/tcp.c to detect
3764 * changes between the TCP and BPF versions. Ideally this should never happen.
3765 * If it does, we need to add code to convert them before calling
3766 * the BPF sock_ops function.
3767 */
3768enum {
3769        BPF_TCP_ESTABLISHED = 1,
3770        BPF_TCP_SYN_SENT,
3771        BPF_TCP_SYN_RECV,
3772        BPF_TCP_FIN_WAIT1,
3773        BPF_TCP_FIN_WAIT2,
3774        BPF_TCP_TIME_WAIT,
3775        BPF_TCP_CLOSE,
3776        BPF_TCP_CLOSE_WAIT,
3777        BPF_TCP_LAST_ACK,
3778        BPF_TCP_LISTEN,
3779        BPF_TCP_CLOSING,        /* Now a valid state */
3780        BPF_TCP_NEW_SYN_RECV,
3781
3782        BPF_TCP_MAX_STATES      /* Leave at the end! */
3783};
3784
3785enum {
3786        TCP_BPF_IW              = 1001, /* Set TCP initial congestion window */
3787        TCP_BPF_SNDCWND_CLAMP   = 1002, /* Set sndcwnd_clamp */
3788};
3789
3790struct bpf_perf_event_value {
3791        __u64 counter;
3792        __u64 enabled;
3793        __u64 running;
3794};
3795
3796enum {
3797        BPF_DEVCG_ACC_MKNOD     = (1ULL << 0),
3798        BPF_DEVCG_ACC_READ      = (1ULL << 1),
3799        BPF_DEVCG_ACC_WRITE     = (1ULL << 2),
3800};
3801
3802enum {
3803        BPF_DEVCG_DEV_BLOCK     = (1ULL << 0),
3804        BPF_DEVCG_DEV_CHAR      = (1ULL << 1),
3805};
3806
3807struct bpf_cgroup_dev_ctx {
3808        /* access_type encoded as (BPF_DEVCG_ACC_* << 16) | BPF_DEVCG_DEV_* */
3809        __u32 access_type;
3810        __u32 major;
3811        __u32 minor;
3812};
3813
3814struct bpf_raw_tracepoint_args {
3815        __u64 args[0];
3816};
3817
3818/* DIRECT:  Skip the FIB rules and go to FIB table associated with device
3819 * OUTPUT:  Do lookup from egress perspective; default is ingress
3820 */
3821enum {
3822        BPF_FIB_LOOKUP_DIRECT  = (1U << 0),
3823        BPF_FIB_LOOKUP_OUTPUT  = (1U << 1),
3824};
3825
3826enum {
3827        BPF_FIB_LKUP_RET_SUCCESS,      /* lookup successful */
3828        BPF_FIB_LKUP_RET_BLACKHOLE,    /* dest is blackholed; can be dropped */
3829        BPF_FIB_LKUP_RET_UNREACHABLE,  /* dest is unreachable; can be dropped */
3830        BPF_FIB_LKUP_RET_PROHIBIT,     /* dest not allowed; can be dropped */
3831        BPF_FIB_LKUP_RET_NOT_FWDED,    /* packet is not forwarded */
3832        BPF_FIB_LKUP_RET_FWD_DISABLED, /* fwding is not enabled on ingress */
3833        BPF_FIB_LKUP_RET_UNSUPP_LWT,   /* fwd requires encapsulation */
3834        BPF_FIB_LKUP_RET_NO_NEIGH,     /* no neighbor entry for nh */
3835        BPF_FIB_LKUP_RET_FRAG_NEEDED,  /* fragmentation required to fwd */
3836};
3837
3838struct bpf_fib_lookup {
3839        /* input:  network family for lookup (AF_INET, AF_INET6)
3840         * output: network family of egress nexthop
3841         */
3842        __u8    family;
3843
3844        /* set if lookup is to consider L4 data - e.g., FIB rules */
3845        __u8    l4_protocol;
3846        __be16  sport;
3847        __be16  dport;
3848
3849        /* total length of packet from network header - used for MTU check */
3850        __u16   tot_len;
3851
3852        /* input: L3 device index for lookup
3853         * output: device index from FIB lookup
3854         */
3855        __u32   ifindex;
3856
3857        union {
3858                /* inputs to lookup */
3859                __u8    tos;            /* AF_INET  */
3860                __be32  flowinfo;       /* AF_INET6, flow_label + priority */
3861
3862                /* output: metric of fib result (IPv4/IPv6 only) */
3863                __u32   rt_metric;
3864        };
3865
3866        union {
3867                __be32          ipv4_src;
3868                __u32           ipv6_src[4];  /* in6_addr; network order */
3869        };
3870
3871        /* input to bpf_fib_lookup, ipv{4,6}_dst is destination address in
3872         * network header. output: bpf_fib_lookup sets to gateway address
3873         * if FIB lookup returns gateway route
3874         */
3875        union {
3876                __be32          ipv4_dst;
3877                __u32           ipv6_dst[4];  /* in6_addr; network order */
3878        };
3879
3880        /* output */
3881        __be16  h_vlan_proto;
3882        __be16  h_vlan_TCI;
3883        __u8    smac[6];     /* ETH_ALEN */
3884        __u8    dmac[6];     /* ETH_ALEN */
3885};
3886
3887enum bpf_task_fd_type {
3888        BPF_FD_TYPE_RAW_TRACEPOINT,     /* tp name */
3889        BPF_FD_TYPE_TRACEPOINT,         /* tp name */
3890        BPF_FD_TYPE_KPROBE,             /* (symbol + offset) or addr */
3891        BPF_FD_TYPE_KRETPROBE,          /* (symbol + offset) or addr */
3892        BPF_FD_TYPE_UPROBE,             /* filename + offset */
3893        BPF_FD_TYPE_URETPROBE,          /* filename + offset */
3894};
3895
3896enum {
3897        BPF_FLOW_DISSECTOR_F_PARSE_1ST_FRAG             = (1U << 0),
3898        BPF_FLOW_DISSECTOR_F_STOP_AT_FLOW_LABEL         = (1U << 1),
3899        BPF_FLOW_DISSECTOR_F_STOP_AT_ENCAP              = (1U << 2),
3900};
3901
3902struct bpf_flow_keys {
3903        __u16   nhoff;
3904        __u16   thoff;
3905        __u16   addr_proto;                     /* ETH_P_* of valid addrs */
3906        __u8    is_frag;
3907        __u8    is_first_frag;
3908        __u8    is_encap;
3909        __u8    ip_proto;
3910        __be16  n_proto;
3911        __be16  sport;
3912        __be16  dport;
3913        union {
3914                struct {
3915                        __be32  ipv4_src;
3916                        __be32  ipv4_dst;
3917                };
3918                struct {
3919                        __u32   ipv6_src[4];    /* in6_addr; network order */
3920                        __u32   ipv6_dst[4];    /* in6_addr; network order */
3921                };
3922        };
3923        __u32   flags;
3924        __be32  flow_label;
3925};
3926
3927struct bpf_func_info {
3928        __u32   insn_off;
3929        __u32   type_id;
3930};
3931
3932#define BPF_LINE_INFO_LINE_NUM(line_col)        ((line_col) >> 10)
3933#define BPF_LINE_INFO_LINE_COL(line_col)        ((line_col) & 0x3ff)
3934
3935struct bpf_line_info {
3936        __u32   insn_off;
3937        __u32   file_name_off;
3938        __u32   line_off;
3939        __u32   line_col;
3940};
3941
3942struct bpf_spin_lock {
3943        __u32   val;
3944};
3945
3946struct bpf_sysctl {
3947        __u32   write;          /* Sysctl is being read (= 0) or written (= 1).
3948                                 * Allows 1,2,4-byte read, but no write.
3949                                 */
3950        __u32   file_pos;       /* Sysctl file position to read from, write to.
3951                                 * Allows 1,2,4-byte read an 4-byte write.
3952                                 */
3953};
3954
3955struct bpf_sockopt {
3956        __bpf_md_ptr(struct bpf_sock *, sk);
3957        __bpf_md_ptr(void *, optval);
3958        __bpf_md_ptr(void *, optval_end);
3959
3960        __s32   level;
3961        __s32   optname;
3962        __s32   optlen;
3963        __s32   retval;
3964};
3965
3966struct bpf_pidns_info {
3967        __u32 pid;
3968        __u32 tgid;
3969};
3970#endif /* _UAPI__LINUX_BPF_H__ */
3971