linux/tools/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};
 111
 112enum bpf_map_type {
 113        BPF_MAP_TYPE_UNSPEC,
 114        BPF_MAP_TYPE_HASH,
 115        BPF_MAP_TYPE_ARRAY,
 116        BPF_MAP_TYPE_PROG_ARRAY,
 117        BPF_MAP_TYPE_PERF_EVENT_ARRAY,
 118        BPF_MAP_TYPE_PERCPU_HASH,
 119        BPF_MAP_TYPE_PERCPU_ARRAY,
 120        BPF_MAP_TYPE_STACK_TRACE,
 121        BPF_MAP_TYPE_CGROUP_ARRAY,
 122        BPF_MAP_TYPE_LRU_HASH,
 123        BPF_MAP_TYPE_LRU_PERCPU_HASH,
 124        BPF_MAP_TYPE_LPM_TRIE,
 125        BPF_MAP_TYPE_ARRAY_OF_MAPS,
 126        BPF_MAP_TYPE_HASH_OF_MAPS,
 127        BPF_MAP_TYPE_DEVMAP,
 128        BPF_MAP_TYPE_SOCKMAP,
 129        BPF_MAP_TYPE_CPUMAP,
 130        BPF_MAP_TYPE_XSKMAP,
 131        BPF_MAP_TYPE_SOCKHASH,
 132        BPF_MAP_TYPE_CGROUP_STORAGE,
 133        BPF_MAP_TYPE_REUSEPORT_SOCKARRAY,
 134        BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE,
 135        BPF_MAP_TYPE_QUEUE,
 136        BPF_MAP_TYPE_STACK,
 137        BPF_MAP_TYPE_SK_STORAGE,
 138        BPF_MAP_TYPE_DEVMAP_HASH,
 139};
 140
 141/* Note that tracing related programs such as
 142 * BPF_PROG_TYPE_{KPROBE,TRACEPOINT,PERF_EVENT,RAW_TRACEPOINT}
 143 * are not subject to a stable API since kernel internal data
 144 * structures can change from release to release and may
 145 * therefore break existing tracing BPF programs. Tracing BPF
 146 * programs correspond to /a/ specific kernel which is to be
 147 * analyzed, and not /a/ specific kernel /and/ all future ones.
 148 */
 149enum bpf_prog_type {
 150        BPF_PROG_TYPE_UNSPEC,
 151        BPF_PROG_TYPE_SOCKET_FILTER,
 152        BPF_PROG_TYPE_KPROBE,
 153        BPF_PROG_TYPE_SCHED_CLS,
 154        BPF_PROG_TYPE_SCHED_ACT,
 155        BPF_PROG_TYPE_TRACEPOINT,
 156        BPF_PROG_TYPE_XDP,
 157        BPF_PROG_TYPE_PERF_EVENT,
 158        BPF_PROG_TYPE_CGROUP_SKB,
 159        BPF_PROG_TYPE_CGROUP_SOCK,
 160        BPF_PROG_TYPE_LWT_IN,
 161        BPF_PROG_TYPE_LWT_OUT,
 162        BPF_PROG_TYPE_LWT_XMIT,
 163        BPF_PROG_TYPE_SOCK_OPS,
 164        BPF_PROG_TYPE_SK_SKB,
 165        BPF_PROG_TYPE_CGROUP_DEVICE,
 166        BPF_PROG_TYPE_SK_MSG,
 167        BPF_PROG_TYPE_RAW_TRACEPOINT,
 168        BPF_PROG_TYPE_CGROUP_SOCK_ADDR,
 169        BPF_PROG_TYPE_LWT_SEG6LOCAL,
 170        BPF_PROG_TYPE_LIRC_MODE2,
 171        BPF_PROG_TYPE_SK_REUSEPORT,
 172        BPF_PROG_TYPE_FLOW_DISSECTOR,
 173        BPF_PROG_TYPE_CGROUP_SYSCTL,
 174        BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE,
 175        BPF_PROG_TYPE_CGROUP_SOCKOPT,
 176};
 177
 178enum bpf_attach_type {
 179        BPF_CGROUP_INET_INGRESS,
 180        BPF_CGROUP_INET_EGRESS,
 181        BPF_CGROUP_INET_SOCK_CREATE,
 182        BPF_CGROUP_SOCK_OPS,
 183        BPF_SK_SKB_STREAM_PARSER,
 184        BPF_SK_SKB_STREAM_VERDICT,
 185        BPF_CGROUP_DEVICE,
 186        BPF_SK_MSG_VERDICT,
 187        BPF_CGROUP_INET4_BIND,
 188        BPF_CGROUP_INET6_BIND,
 189        BPF_CGROUP_INET4_CONNECT,
 190        BPF_CGROUP_INET6_CONNECT,
 191        BPF_CGROUP_INET4_POST_BIND,
 192        BPF_CGROUP_INET6_POST_BIND,
 193        BPF_CGROUP_UDP4_SENDMSG,
 194        BPF_CGROUP_UDP6_SENDMSG,
 195        BPF_LIRC_MODE2,
 196        BPF_FLOW_DISSECTOR,
 197        BPF_CGROUP_SYSCTL,
 198        BPF_CGROUP_UDP4_RECVMSG,
 199        BPF_CGROUP_UDP6_RECVMSG,
 200        BPF_CGROUP_GETSOCKOPT,
 201        BPF_CGROUP_SETSOCKOPT,
 202        __MAX_BPF_ATTACH_TYPE
 203};
 204
 205#define MAX_BPF_ATTACH_TYPE __MAX_BPF_ATTACH_TYPE
 206
 207/* cgroup-bpf attach flags used in BPF_PROG_ATTACH command
 208 *
 209 * NONE(default): No further bpf programs allowed in the subtree.
 210 *
 211 * BPF_F_ALLOW_OVERRIDE: If a sub-cgroup installs some bpf program,
 212 * the program in this cgroup yields to sub-cgroup program.
 213 *
 214 * BPF_F_ALLOW_MULTI: If a sub-cgroup installs some bpf program,
 215 * that cgroup program gets run in addition to the program in this cgroup.
 216 *
 217 * Only one program is allowed to be attached to a cgroup with
 218 * NONE or BPF_F_ALLOW_OVERRIDE flag.
 219 * Attaching another program on top of NONE or BPF_F_ALLOW_OVERRIDE will
 220 * release old program and attach the new one. Attach flags has to match.
 221 *
 222 * Multiple programs are allowed to be attached to a cgroup with
 223 * BPF_F_ALLOW_MULTI flag. They are executed in FIFO order
 224 * (those that were attached first, run first)
 225 * The programs of sub-cgroup are executed first, then programs of
 226 * this cgroup and then programs of parent cgroup.
 227 * When children program makes decision (like picking TCP CA or sock bind)
 228 * parent program has a chance to override it.
 229 *
 230 * A cgroup with MULTI or OVERRIDE flag allows any attach flags in sub-cgroups.
 231 * A cgroup with NONE doesn't allow any programs in sub-cgroups.
 232 * Ex1:
 233 * cgrp1 (MULTI progs A, B) ->
 234 *    cgrp2 (OVERRIDE prog C) ->
 235 *      cgrp3 (MULTI prog D) ->
 236 *        cgrp4 (OVERRIDE prog E) ->
 237 *          cgrp5 (NONE prog F)
 238 * the event in cgrp5 triggers execution of F,D,A,B in that order.
 239 * if prog F is detached, the execution is E,D,A,B
 240 * if prog F and D are detached, the execution is E,A,B
 241 * if prog F, E and D are detached, the execution is C,A,B
 242 *
 243 * All eligible programs are executed regardless of return code from
 244 * earlier programs.
 245 */
 246#define BPF_F_ALLOW_OVERRIDE    (1U << 0)
 247#define BPF_F_ALLOW_MULTI       (1U << 1)
 248
 249/* If BPF_F_STRICT_ALIGNMENT is used in BPF_PROG_LOAD command, the
 250 * verifier will perform strict alignment checking as if the kernel
 251 * has been built with CONFIG_EFFICIENT_UNALIGNED_ACCESS not set,
 252 * and NET_IP_ALIGN defined to 2.
 253 */
 254#define BPF_F_STRICT_ALIGNMENT  (1U << 0)
 255
 256/* If BPF_F_ANY_ALIGNMENT is used in BPF_PROF_LOAD command, the
 257 * verifier will allow any alignment whatsoever.  On platforms
 258 * with strict alignment requirements for loads ands stores (such
 259 * as sparc and mips) the verifier validates that all loads and
 260 * stores provably follow this requirement.  This flag turns that
 261 * checking and enforcement off.
 262 *
 263 * It is mostly used for testing when we want to validate the
 264 * context and memory access aspects of the verifier, but because
 265 * of an unaligned access the alignment check would trigger before
 266 * the one we are interested in.
 267 */
 268#define BPF_F_ANY_ALIGNMENT     (1U << 1)
 269
 270/* BPF_F_TEST_RND_HI32 is used in BPF_PROG_LOAD command for testing purpose.
 271 * Verifier does sub-register def/use analysis and identifies instructions whose
 272 * def only matters for low 32-bit, high 32-bit is never referenced later
 273 * through implicit zero extension. Therefore verifier notifies JIT back-ends
 274 * that it is safe to ignore clearing high 32-bit for these instructions. This
 275 * saves some back-ends a lot of code-gen. However such optimization is not
 276 * necessary on some arches, for example x86_64, arm64 etc, whose JIT back-ends
 277 * hence hasn't used verifier's analysis result. But, we really want to have a
 278 * way to be able to verify the correctness of the described optimization on
 279 * x86_64 on which testsuites are frequently exercised.
 280 *
 281 * So, this flag is introduced. Once it is set, verifier will randomize high
 282 * 32-bit for those instructions who has been identified as safe to ignore them.
 283 * Then, if verifier is not doing correct analysis, such randomization will
 284 * regress tests to expose bugs.
 285 */
 286#define BPF_F_TEST_RND_HI32     (1U << 2)
 287
 288/* The verifier internal test flag. Behavior is undefined */
 289#define BPF_F_TEST_STATE_FREQ   (1U << 3)
 290
 291/* When BPF ldimm64's insn[0].src_reg != 0 then this can have
 292 * two extensions:
 293 *
 294 * insn[0].src_reg:  BPF_PSEUDO_MAP_FD   BPF_PSEUDO_MAP_VALUE
 295 * insn[0].imm:      map fd              map fd
 296 * insn[1].imm:      0                   offset into value
 297 * insn[0].off:      0                   0
 298 * insn[1].off:      0                   0
 299 * ldimm64 rewrite:  address of map      address of map[0]+offset
 300 * verifier type:    CONST_PTR_TO_MAP    PTR_TO_MAP_VALUE
 301 */
 302#define BPF_PSEUDO_MAP_FD       1
 303#define BPF_PSEUDO_MAP_VALUE    2
 304
 305/* when bpf_call->src_reg == BPF_PSEUDO_CALL, bpf_call->imm == pc-relative
 306 * offset to another bpf function
 307 */
 308#define BPF_PSEUDO_CALL         1
 309
 310/* flags for BPF_MAP_UPDATE_ELEM command */
 311#define BPF_ANY         0 /* create new element or update existing */
 312#define BPF_NOEXIST     1 /* create new element if it didn't exist */
 313#define BPF_EXIST       2 /* update existing element */
 314#define BPF_F_LOCK      4 /* spin_lock-ed map_lookup/map_update */
 315
 316/* flags for BPF_MAP_CREATE command */
 317#define BPF_F_NO_PREALLOC       (1U << 0)
 318/* Instead of having one common LRU list in the
 319 * BPF_MAP_TYPE_LRU_[PERCPU_]HASH map, use a percpu LRU list
 320 * which can scale and perform better.
 321 * Note, the LRU nodes (including free nodes) cannot be moved
 322 * across different LRU lists.
 323 */
 324#define BPF_F_NO_COMMON_LRU     (1U << 1)
 325/* Specify numa node during map creation */
 326#define BPF_F_NUMA_NODE         (1U << 2)
 327
 328#define BPF_OBJ_NAME_LEN 16U
 329
 330/* Flags for accessing BPF object from syscall side. */
 331#define BPF_F_RDONLY            (1U << 3)
 332#define BPF_F_WRONLY            (1U << 4)
 333
 334/* Flag for stack_map, store build_id+offset instead of pointer */
 335#define BPF_F_STACK_BUILD_ID    (1U << 5)
 336
 337/* Zero-initialize hash function seed. This should only be used for testing. */
 338#define BPF_F_ZERO_SEED         (1U << 6)
 339
 340/* Flags for accessing BPF object from program side. */
 341#define BPF_F_RDONLY_PROG       (1U << 7)
 342#define BPF_F_WRONLY_PROG       (1U << 8)
 343
 344/* Clone map from listener for newly accepted socket */
 345#define BPF_F_CLONE             (1U << 9)
 346
 347/* flags for BPF_PROG_QUERY */
 348#define BPF_F_QUERY_EFFECTIVE   (1U << 0)
 349
 350enum bpf_stack_build_id_status {
 351        /* user space need an empty entry to identify end of a trace */
 352        BPF_STACK_BUILD_ID_EMPTY = 0,
 353        /* with valid build_id and offset */
 354        BPF_STACK_BUILD_ID_VALID = 1,
 355        /* couldn't get build_id, fallback to ip */
 356        BPF_STACK_BUILD_ID_IP = 2,
 357};
 358
 359#define BPF_BUILD_ID_SIZE 20
 360struct bpf_stack_build_id {
 361        __s32           status;
 362        unsigned char   build_id[BPF_BUILD_ID_SIZE];
 363        union {
 364                __u64   offset;
 365                __u64   ip;
 366        };
 367};
 368
 369union bpf_attr {
 370        struct { /* anonymous struct used by BPF_MAP_CREATE command */
 371                __u32   map_type;       /* one of enum bpf_map_type */
 372                __u32   key_size;       /* size of key in bytes */
 373                __u32   value_size;     /* size of value in bytes */
 374                __u32   max_entries;    /* max number of entries in a map */
 375                __u32   map_flags;      /* BPF_MAP_CREATE related
 376                                         * flags defined above.
 377                                         */
 378                __u32   inner_map_fd;   /* fd pointing to the inner map */
 379                __u32   numa_node;      /* numa node (effective only if
 380                                         * BPF_F_NUMA_NODE is set).
 381                                         */
 382                char    map_name[BPF_OBJ_NAME_LEN];
 383                __u32   map_ifindex;    /* ifindex of netdev to create on */
 384                __u32   btf_fd;         /* fd pointing to a BTF type data */
 385                __u32   btf_key_type_id;        /* BTF type_id of the key */
 386                __u32   btf_value_type_id;      /* BTF type_id of the value */
 387        };
 388
 389        struct { /* anonymous struct used by BPF_MAP_*_ELEM commands */
 390                __u32           map_fd;
 391                __aligned_u64   key;
 392                union {
 393                        __aligned_u64 value;
 394                        __aligned_u64 next_key;
 395                };
 396                __u64           flags;
 397        };
 398
 399        struct { /* anonymous struct used by BPF_PROG_LOAD command */
 400                __u32           prog_type;      /* one of enum bpf_prog_type */
 401                __u32           insn_cnt;
 402                __aligned_u64   insns;
 403                __aligned_u64   license;
 404                __u32           log_level;      /* verbosity level of verifier */
 405                __u32           log_size;       /* size of user buffer */
 406                __aligned_u64   log_buf;        /* user supplied buffer */
 407                __u32           kern_version;   /* not used */
 408                __u32           prog_flags;
 409                char            prog_name[BPF_OBJ_NAME_LEN];
 410                __u32           prog_ifindex;   /* ifindex of netdev to prep for */
 411                /* For some prog types expected attach type must be known at
 412                 * load time to verify attach type specific parts of prog
 413                 * (context accesses, allowed helpers, etc).
 414                 */
 415                __u32           expected_attach_type;
 416                __u32           prog_btf_fd;    /* fd pointing to BTF type data */
 417                __u32           func_info_rec_size;     /* userspace bpf_func_info size */
 418                __aligned_u64   func_info;      /* func info */
 419                __u32           func_info_cnt;  /* number of bpf_func_info records */
 420                __u32           line_info_rec_size;     /* userspace bpf_line_info size */
 421                __aligned_u64   line_info;      /* line info */
 422                __u32           line_info_cnt;  /* number of bpf_line_info records */
 423        };
 424
 425        struct { /* anonymous struct used by BPF_OBJ_* commands */
 426                __aligned_u64   pathname;
 427                __u32           bpf_fd;
 428                __u32           file_flags;
 429        };
 430
 431        struct { /* anonymous struct used by BPF_PROG_ATTACH/DETACH commands */
 432                __u32           target_fd;      /* container object to attach to */
 433                __u32           attach_bpf_fd;  /* eBPF program to attach */
 434                __u32           attach_type;
 435                __u32           attach_flags;
 436        };
 437
 438        struct { /* anonymous struct used by BPF_PROG_TEST_RUN command */
 439                __u32           prog_fd;
 440                __u32           retval;
 441                __u32           data_size_in;   /* input: len of data_in */
 442                __u32           data_size_out;  /* input/output: len of data_out
 443                                                 *   returns ENOSPC if data_out
 444                                                 *   is too small.
 445                                                 */
 446                __aligned_u64   data_in;
 447                __aligned_u64   data_out;
 448                __u32           repeat;
 449                __u32           duration;
 450                __u32           ctx_size_in;    /* input: len of ctx_in */
 451                __u32           ctx_size_out;   /* input/output: len of ctx_out
 452                                                 *   returns ENOSPC if ctx_out
 453                                                 *   is too small.
 454                                                 */
 455                __aligned_u64   ctx_in;
 456                __aligned_u64   ctx_out;
 457        } test;
 458
 459        struct { /* anonymous struct used by BPF_*_GET_*_ID */
 460                union {
 461                        __u32           start_id;
 462                        __u32           prog_id;
 463                        __u32           map_id;
 464                        __u32           btf_id;
 465                };
 466                __u32           next_id;
 467                __u32           open_flags;
 468        };
 469
 470        struct { /* anonymous struct used by BPF_OBJ_GET_INFO_BY_FD */
 471                __u32           bpf_fd;
 472                __u32           info_len;
 473                __aligned_u64   info;
 474        } info;
 475
 476        struct { /* anonymous struct used by BPF_PROG_QUERY command */
 477                __u32           target_fd;      /* container object to query */
 478                __u32           attach_type;
 479                __u32           query_flags;
 480                __u32           attach_flags;
 481                __aligned_u64   prog_ids;
 482                __u32           prog_cnt;
 483        } query;
 484
 485        struct {
 486                __u64 name;
 487                __u32 prog_fd;
 488        } raw_tracepoint;
 489
 490        struct { /* anonymous struct for BPF_BTF_LOAD */
 491                __aligned_u64   btf;
 492                __aligned_u64   btf_log_buf;
 493                __u32           btf_size;
 494                __u32           btf_log_size;
 495                __u32           btf_log_level;
 496        };
 497
 498        struct {
 499                __u32           pid;            /* input: pid */
 500                __u32           fd;             /* input: fd */
 501                __u32           flags;          /* input: flags */
 502                __u32           buf_len;        /* input/output: buf len */
 503                __aligned_u64   buf;            /* input/output:
 504                                                 *   tp_name for tracepoint
 505                                                 *   symbol for kprobe
 506                                                 *   filename for uprobe
 507                                                 */
 508                __u32           prog_id;        /* output: prod_id */
 509                __u32           fd_type;        /* output: BPF_FD_TYPE_* */
 510                __u64           probe_offset;   /* output: probe_offset */
 511                __u64           probe_addr;     /* output: probe_addr */
 512        } task_fd_query;
 513} __attribute__((aligned(8)));
 514
 515/* The description below is an attempt at providing documentation to eBPF
 516 * developers about the multiple available eBPF helper functions. It can be
 517 * parsed and used to produce a manual page. The workflow is the following,
 518 * and requires the rst2man utility:
 519 *
 520 *     $ ./scripts/bpf_helpers_doc.py \
 521 *             --filename include/uapi/linux/bpf.h > /tmp/bpf-helpers.rst
 522 *     $ rst2man /tmp/bpf-helpers.rst > /tmp/bpf-helpers.7
 523 *     $ man /tmp/bpf-helpers.7
 524 *
 525 * Note that in order to produce this external documentation, some RST
 526 * formatting is used in the descriptions to get "bold" and "italics" in
 527 * manual pages. Also note that the few trailing white spaces are
 528 * intentional, removing them would break paragraphs for rst2man.
 529 *
 530 * Start of BPF helper function descriptions:
 531 *
 532 * void *bpf_map_lookup_elem(struct bpf_map *map, const void *key)
 533 *      Description
 534 *              Perform a lookup in *map* for an entry associated to *key*.
 535 *      Return
 536 *              Map value associated to *key*, or **NULL** if no entry was
 537 *              found.
 538 *
 539 * int bpf_map_update_elem(struct bpf_map *map, const void *key, const void *value, u64 flags)
 540 *      Description
 541 *              Add or update the value of the entry associated to *key* in
 542 *              *map* with *value*. *flags* is one of:
 543 *
 544 *              **BPF_NOEXIST**
 545 *                      The entry for *key* must not exist in the map.
 546 *              **BPF_EXIST**
 547 *                      The entry for *key* must already exist in the map.
 548 *              **BPF_ANY**
 549 *                      No condition on the existence of the entry for *key*.
 550 *
 551 *              Flag value **BPF_NOEXIST** cannot be used for maps of types
 552 *              **BPF_MAP_TYPE_ARRAY** or **BPF_MAP_TYPE_PERCPU_ARRAY**  (all
 553 *              elements always exist), the helper would return an error.
 554 *      Return
 555 *              0 on success, or a negative error in case of failure.
 556 *
 557 * int bpf_map_delete_elem(struct bpf_map *map, const void *key)
 558 *      Description
 559 *              Delete entry with *key* from *map*.
 560 *      Return
 561 *              0 on success, or a negative error in case of failure.
 562 *
 563 * int bpf_probe_read(void *dst, u32 size, const void *src)
 564 *      Description
 565 *              For tracing programs, safely attempt to read *size* bytes from
 566 *              address *src* and store the data in *dst*.
 567 *      Return
 568 *              0 on success, or a negative error in case of failure.
 569 *
 570 * u64 bpf_ktime_get_ns(void)
 571 *      Description
 572 *              Return the time elapsed since system boot, in nanoseconds.
 573 *      Return
 574 *              Current *ktime*.
 575 *
 576 * int bpf_trace_printk(const char *fmt, u32 fmt_size, ...)
 577 *      Description
 578 *              This helper is a "printk()-like" facility for debugging. It
 579 *              prints a message defined by format *fmt* (of size *fmt_size*)
 580 *              to file *\/sys/kernel/debug/tracing/trace* from DebugFS, if
 581 *              available. It can take up to three additional **u64**
 582 *              arguments (as an eBPF helpers, the total number of arguments is
 583 *              limited to five).
 584 *
 585 *              Each time the helper is called, it appends a line to the trace.
 586 *              Lines are discarded while *\/sys/kernel/debug/tracing/trace* is
 587 *              open, use *\/sys/kernel/debug/tracing/trace_pipe* to avoid this.
 588 *              The format of the trace is customizable, and the exact output
 589 *              one will get depends on the options set in
 590 *              *\/sys/kernel/debug/tracing/trace_options* (see also the
 591 *              *README* file under the same directory). However, it usually
 592 *              defaults to something like:
 593 *
 594 *              ::
 595 *
 596 *                      telnet-470   [001] .N.. 419421.045894: 0x00000001: <formatted msg>
 597 *
 598 *              In the above:
 599 *
 600 *                      * ``telnet`` is the name of the current task.
 601 *                      * ``470`` is the PID of the current task.
 602 *                      * ``001`` is the CPU number on which the task is
 603 *                        running.
 604 *                      * In ``.N..``, each character refers to a set of
 605 *                        options (whether irqs are enabled, scheduling
 606 *                        options, whether hard/softirqs are running, level of
 607 *                        preempt_disabled respectively). **N** means that
 608 *                        **TIF_NEED_RESCHED** and **PREEMPT_NEED_RESCHED**
 609 *                        are set.
 610 *                      * ``419421.045894`` is a timestamp.
 611 *                      * ``0x00000001`` is a fake value used by BPF for the
 612 *                        instruction pointer register.
 613 *                      * ``<formatted msg>`` is the message formatted with
 614 *                        *fmt*.
 615 *
 616 *              The conversion specifiers supported by *fmt* are similar, but
 617 *              more limited than for printk(). They are **%d**, **%i**,
 618 *              **%u**, **%x**, **%ld**, **%li**, **%lu**, **%lx**, **%lld**,
 619 *              **%lli**, **%llu**, **%llx**, **%p**, **%s**. No modifier (size
 620 *              of field, padding with zeroes, etc.) is available, and the
 621 *              helper will return **-EINVAL** (but print nothing) if it
 622 *              encounters an unknown specifier.
 623 *
 624 *              Also, note that **bpf_trace_printk**\ () is slow, and should
 625 *              only be used for debugging purposes. For this reason, a notice
 626 *              bloc (spanning several lines) is printed to kernel logs and
 627 *              states that the helper should not be used "for production use"
 628 *              the first time this helper is used (or more precisely, when
 629 *              **trace_printk**\ () buffers are allocated). For passing values
 630 *              to user space, perf events should be preferred.
 631 *      Return
 632 *              The number of bytes written to the buffer, or a negative error
 633 *              in case of failure.
 634 *
 635 * u32 bpf_get_prandom_u32(void)
 636 *      Description
 637 *              Get a pseudo-random number.
 638 *
 639 *              From a security point of view, this helper uses its own
 640 *              pseudo-random internal state, and cannot be used to infer the
 641 *              seed of other random functions in the kernel. However, it is
 642 *              essential to note that the generator used by the helper is not
 643 *              cryptographically secure.
 644 *      Return
 645 *              A random 32-bit unsigned value.
 646 *
 647 * u32 bpf_get_smp_processor_id(void)
 648 *      Description
 649 *              Get the SMP (symmetric multiprocessing) processor id. Note that
 650 *              all programs run with preemption disabled, which means that the
 651 *              SMP processor id is stable during all the execution of the
 652 *              program.
 653 *      Return
 654 *              The SMP id of the processor running the program.
 655 *
 656 * int bpf_skb_store_bytes(struct sk_buff *skb, u32 offset, const void *from, u32 len, u64 flags)
 657 *      Description
 658 *              Store *len* bytes from address *from* into the packet
 659 *              associated to *skb*, at *offset*. *flags* are a combination of
 660 *              **BPF_F_RECOMPUTE_CSUM** (automatically recompute the
 661 *              checksum for the packet after storing the bytes) and
 662 *              **BPF_F_INVALIDATE_HASH** (set *skb*\ **->hash**, *skb*\
 663 *              **->swhash** and *skb*\ **->l4hash** to 0).
 664 *
 665 *              A call to this helper is susceptible to change the underlying
 666 *              packet buffer. Therefore, at load time, all checks on pointers
 667 *              previously done by the verifier are invalidated and must be
 668 *              performed again, if the helper is used in combination with
 669 *              direct packet access.
 670 *      Return
 671 *              0 on success, or a negative error in case of failure.
 672 *
 673 * int bpf_l3_csum_replace(struct sk_buff *skb, u32 offset, u64 from, u64 to, u64 size)
 674 *      Description
 675 *              Recompute the layer 3 (e.g. IP) checksum for the packet
 676 *              associated to *skb*. Computation is incremental, so the helper
 677 *              must know the former value of the header field that was
 678 *              modified (*from*), the new value of this field (*to*), and the
 679 *              number of bytes (2 or 4) for this field, stored in *size*.
 680 *              Alternatively, it is possible to store the difference between
 681 *              the previous and the new values of the header field in *to*, by
 682 *              setting *from* and *size* to 0. For both methods, *offset*
 683 *              indicates the location of the IP checksum within the packet.
 684 *
 685 *              This helper works in combination with **bpf_csum_diff**\ (),
 686 *              which does not update the checksum in-place, but offers more
 687 *              flexibility and can handle sizes larger than 2 or 4 for the
 688 *              checksum to update.
 689 *
 690 *              A call to this helper is susceptible to change the underlying
 691 *              packet buffer. Therefore, at load time, all checks on pointers
 692 *              previously done by the verifier are invalidated and must be
 693 *              performed again, if the helper is used in combination with
 694 *              direct packet access.
 695 *      Return
 696 *              0 on success, or a negative error in case of failure.
 697 *
 698 * int bpf_l4_csum_replace(struct sk_buff *skb, u32 offset, u64 from, u64 to, u64 flags)
 699 *      Description
 700 *              Recompute the layer 4 (e.g. TCP, UDP or ICMP) checksum for the
 701 *              packet associated to *skb*. Computation is incremental, so the
 702 *              helper must know the former value of the header field that was
 703 *              modified (*from*), the new value of this field (*to*), and the
 704 *              number of bytes (2 or 4) for this field, stored on the lowest
 705 *              four bits of *flags*. Alternatively, it is possible to store
 706 *              the difference between the previous and the new values of the
 707 *              header field in *to*, by setting *from* and the four lowest
 708 *              bits of *flags* to 0. For both methods, *offset* indicates the
 709 *              location of the IP checksum within the packet. In addition to
 710 *              the size of the field, *flags* can be added (bitwise OR) actual
 711 *              flags. With **BPF_F_MARK_MANGLED_0**, a null checksum is left
 712 *              untouched (unless **BPF_F_MARK_ENFORCE** is added as well), and
 713 *              for updates resulting in a null checksum the value is set to
 714 *              **CSUM_MANGLED_0** instead. Flag **BPF_F_PSEUDO_HDR** indicates
 715 *              the checksum is to be computed against a pseudo-header.
 716 *
 717 *              This helper works in combination with **bpf_csum_diff**\ (),
 718 *              which does not update the checksum in-place, but offers more
 719 *              flexibility and can handle sizes larger than 2 or 4 for the
 720 *              checksum to update.
 721 *
 722 *              A call to this helper is susceptible to change the underlying
 723 *              packet buffer. Therefore, at load time, all checks on pointers
 724 *              previously done by the verifier are invalidated and must be
 725 *              performed again, if the helper is used in combination with
 726 *              direct packet access.
 727 *      Return
 728 *              0 on success, or a negative error in case of failure.
 729 *
 730 * int bpf_tail_call(void *ctx, struct bpf_map *prog_array_map, u32 index)
 731 *      Description
 732 *              This special helper is used to trigger a "tail call", or in
 733 *              other words, to jump into another eBPF program. The same stack
 734 *              frame is used (but values on stack and in registers for the
 735 *              caller are not accessible to the callee). This mechanism allows
 736 *              for program chaining, either for raising the maximum number of
 737 *              available eBPF instructions, or to execute given programs in
 738 *              conditional blocks. For security reasons, there is an upper
 739 *              limit to the number of successive tail calls that can be
 740 *              performed.
 741 *
 742 *              Upon call of this helper, the program attempts to jump into a
 743 *              program referenced at index *index* in *prog_array_map*, a
 744 *              special map of type **BPF_MAP_TYPE_PROG_ARRAY**, and passes
 745 *              *ctx*, a pointer to the context.
 746 *
 747 *              If the call succeeds, the kernel immediately runs the first
 748 *              instruction of the new program. This is not a function call,
 749 *              and it never returns to the previous program. If the call
 750 *              fails, then the helper has no effect, and the caller continues
 751 *              to run its subsequent instructions. A call can fail if the
 752 *              destination program for the jump does not exist (i.e. *index*
 753 *              is superior to the number of entries in *prog_array_map*), or
 754 *              if the maximum number of tail calls has been reached for this
 755 *              chain of programs. This limit is defined in the kernel by the
 756 *              macro **MAX_TAIL_CALL_CNT** (not accessible to user space),
 757 *              which is currently set to 32.
 758 *      Return
 759 *              0 on success, or a negative error in case of failure.
 760 *
 761 * int bpf_clone_redirect(struct sk_buff *skb, u32 ifindex, u64 flags)
 762 *      Description
 763 *              Clone and redirect the packet associated to *skb* to another
 764 *              net device of index *ifindex*. Both ingress and egress
 765 *              interfaces can be used for redirection. The **BPF_F_INGRESS**
 766 *              value in *flags* is used to make the distinction (ingress path
 767 *              is selected if the flag is present, egress path otherwise).
 768 *              This is the only flag supported for now.
 769 *
 770 *              In comparison with **bpf_redirect**\ () helper,
 771 *              **bpf_clone_redirect**\ () has the associated cost of
 772 *              duplicating the packet buffer, but this can be executed out of
 773 *              the eBPF program. Conversely, **bpf_redirect**\ () is more
 774 *              efficient, but it is handled through an action code where the
 775 *              redirection happens only after the eBPF program has returned.
 776 *
 777 *              A call to this helper is susceptible to change the underlying
 778 *              packet buffer. Therefore, at load time, all checks on pointers
 779 *              previously done by the verifier are invalidated and must be
 780 *              performed again, if the helper is used in combination with
 781 *              direct packet access.
 782 *      Return
 783 *              0 on success, or a negative error in case of failure.
 784 *
 785 * u64 bpf_get_current_pid_tgid(void)
 786 *      Return
 787 *              A 64-bit integer containing the current tgid and pid, and
 788 *              created as such:
 789 *              *current_task*\ **->tgid << 32 \|**
 790 *              *current_task*\ **->pid**.
 791 *
 792 * u64 bpf_get_current_uid_gid(void)
 793 *      Return
 794 *              A 64-bit integer containing the current GID and UID, and
 795 *              created as such: *current_gid* **<< 32 \|** *current_uid*.
 796 *
 797 * int bpf_get_current_comm(char *buf, u32 size_of_buf)
 798 *      Description
 799 *              Copy the **comm** attribute of the current task into *buf* of
 800 *              *size_of_buf*. The **comm** attribute contains the name of
 801 *              the executable (excluding the path) for the current task. The
 802 *              *size_of_buf* must be strictly positive. On success, the
 803 *              helper makes sure that the *buf* is NUL-terminated. On failure,
 804 *              it is filled with zeroes.
 805 *      Return
 806 *              0 on success, or a negative error in case of failure.
 807 *
 808 * u32 bpf_get_cgroup_classid(struct sk_buff *skb)
 809 *      Description
 810 *              Retrieve the classid for the current task, i.e. for the net_cls
 811 *              cgroup to which *skb* belongs.
 812 *
 813 *              This helper can be used on TC egress path, but not on ingress.
 814 *
 815 *              The net_cls cgroup provides an interface to tag network packets
 816 *              based on a user-provided identifier for all traffic coming from
 817 *              the tasks belonging to the related cgroup. See also the related
 818 *              kernel documentation, available from the Linux sources in file
 819 *              *Documentation/admin-guide/cgroup-v1/net_cls.rst*.
 820 *
 821 *              The Linux kernel has two versions for cgroups: there are
 822 *              cgroups v1 and cgroups v2. Both are available to users, who can
 823 *              use a mixture of them, but note that the net_cls cgroup is for
 824 *              cgroup v1 only. This makes it incompatible with BPF programs
 825 *              run on cgroups, which is a cgroup-v2-only feature (a socket can
 826 *              only hold data for one version of cgroups at a time).
 827 *
 828 *              This helper is only available is the kernel was compiled with
 829 *              the **CONFIG_CGROUP_NET_CLASSID** configuration option set to
 830 *              "**y**" or to "**m**".
 831 *      Return
 832 *              The classid, or 0 for the default unconfigured classid.
 833 *
 834 * int bpf_skb_vlan_push(struct sk_buff *skb, __be16 vlan_proto, u16 vlan_tci)
 835 *      Description
 836 *              Push a *vlan_tci* (VLAN tag control information) of protocol
 837 *              *vlan_proto* to the packet associated to *skb*, then update
 838 *              the checksum. Note that if *vlan_proto* is different from
 839 *              **ETH_P_8021Q** and **ETH_P_8021AD**, it is considered to
 840 *              be **ETH_P_8021Q**.
 841 *
 842 *              A call to this helper is susceptible to change the underlying
 843 *              packet buffer. Therefore, at load time, all checks on pointers
 844 *              previously done by the verifier are invalidated and must be
 845 *              performed again, if the helper is used in combination with
 846 *              direct packet access.
 847 *      Return
 848 *              0 on success, or a negative error in case of failure.
 849 *
 850 * int bpf_skb_vlan_pop(struct sk_buff *skb)
 851 *      Description
 852 *              Pop a VLAN header from the packet associated to *skb*.
 853 *
 854 *              A call to this helper is susceptible to change the underlying
 855 *              packet buffer. Therefore, at load time, all checks on pointers
 856 *              previously done by the verifier are invalidated and must be
 857 *              performed again, if the helper is used in combination with
 858 *              direct packet access.
 859 *      Return
 860 *              0 on success, or a negative error in case of failure.
 861 *
 862 * int bpf_skb_get_tunnel_key(struct sk_buff *skb, struct bpf_tunnel_key *key, u32 size, u64 flags)
 863 *      Description
 864 *              Get tunnel metadata. This helper takes a pointer *key* to an
 865 *              empty **struct bpf_tunnel_key** of **size**, that will be
 866 *              filled with tunnel metadata for the packet associated to *skb*.
 867 *              The *flags* can be set to **BPF_F_TUNINFO_IPV6**, which
 868 *              indicates that the tunnel is based on IPv6 protocol instead of
 869 *              IPv4.
 870 *
 871 *              The **struct bpf_tunnel_key** is an object that generalizes the
 872 *              principal parameters used by various tunneling protocols into a
 873 *              single struct. This way, it can be used to easily make a
 874 *              decision based on the contents of the encapsulation header,
 875 *              "summarized" in this struct. In particular, it holds the IP
 876 *              address of the remote end (IPv4 or IPv6, depending on the case)
 877 *              in *key*\ **->remote_ipv4** or *key*\ **->remote_ipv6**. Also,
 878 *              this struct exposes the *key*\ **->tunnel_id**, which is
 879 *              generally mapped to a VNI (Virtual Network Identifier), making
 880 *              it programmable together with the **bpf_skb_set_tunnel_key**\
 881 *              () helper.
 882 *
 883 *              Let's imagine that the following code is part of a program
 884 *              attached to the TC ingress interface, on one end of a GRE
 885 *              tunnel, and is supposed to filter out all messages coming from
 886 *              remote ends with IPv4 address other than 10.0.0.1:
 887 *
 888 *              ::
 889 *
 890 *                      int ret;
 891 *                      struct bpf_tunnel_key key = {};
 892 *                      
 893 *                      ret = bpf_skb_get_tunnel_key(skb, &key, sizeof(key), 0);
 894 *                      if (ret < 0)
 895 *                              return TC_ACT_SHOT;     // drop packet
 896 *                      
 897 *                      if (key.remote_ipv4 != 0x0a000001)
 898 *                              return TC_ACT_SHOT;     // drop packet
 899 *                      
 900 *                      return TC_ACT_OK;               // accept packet
 901 *
 902 *              This interface can also be used with all encapsulation devices
 903 *              that can operate in "collect metadata" mode: instead of having
 904 *              one network device per specific configuration, the "collect
 905 *              metadata" mode only requires a single device where the
 906 *              configuration can be extracted from this helper.
 907 *
 908 *              This can be used together with various tunnels such as VXLan,
 909 *              Geneve, GRE or IP in IP (IPIP).
 910 *      Return
 911 *              0 on success, or a negative error in case of failure.
 912 *
 913 * int bpf_skb_set_tunnel_key(struct sk_buff *skb, struct bpf_tunnel_key *key, u32 size, u64 flags)
 914 *      Description
 915 *              Populate tunnel metadata for packet associated to *skb.* The
 916 *              tunnel metadata is set to the contents of *key*, of *size*. The
 917 *              *flags* can be set to a combination of the following values:
 918 *
 919 *              **BPF_F_TUNINFO_IPV6**
 920 *                      Indicate that the tunnel is based on IPv6 protocol
 921 *                      instead of IPv4.
 922 *              **BPF_F_ZERO_CSUM_TX**
 923 *                      For IPv4 packets, add a flag to tunnel metadata
 924 *                      indicating that checksum computation should be skipped
 925 *                      and checksum set to zeroes.
 926 *              **BPF_F_DONT_FRAGMENT**
 927 *                      Add a flag to tunnel metadata indicating that the
 928 *                      packet should not be fragmented.
 929 *              **BPF_F_SEQ_NUMBER**
 930 *                      Add a flag to tunnel metadata indicating that a
 931 *                      sequence number should be added to tunnel header before
 932 *                      sending the packet. This flag was added for GRE
 933 *                      encapsulation, but might be used with other protocols
 934 *                      as well in the future.
 935 *
 936 *              Here is a typical usage on the transmit path:
 937 *
 938 *              ::
 939 *
 940 *                      struct bpf_tunnel_key key;
 941 *                           populate key ...
 942 *                      bpf_skb_set_tunnel_key(skb, &key, sizeof(key), 0);
 943 *                      bpf_clone_redirect(skb, vxlan_dev_ifindex, 0);
 944 *
 945 *              See also the description of the **bpf_skb_get_tunnel_key**\ ()
 946 *              helper for additional information.
 947 *      Return
 948 *              0 on success, or a negative error in case of failure.
 949 *
 950 * u64 bpf_perf_event_read(struct bpf_map *map, u64 flags)
 951 *      Description
 952 *              Read the value of a perf event counter. This helper relies on a
 953 *              *map* of type **BPF_MAP_TYPE_PERF_EVENT_ARRAY**. The nature of
 954 *              the perf event counter is selected when *map* is updated with
 955 *              perf event file descriptors. The *map* is an array whose size
 956 *              is the number of available CPUs, and each cell contains a value
 957 *              relative to one CPU. The value to retrieve is indicated by
 958 *              *flags*, that contains the index of the CPU to look up, masked
 959 *              with **BPF_F_INDEX_MASK**. Alternatively, *flags* can be set to
 960 *              **BPF_F_CURRENT_CPU** to indicate that the value for the
 961 *              current CPU should be retrieved.
 962 *
 963 *              Note that before Linux 4.13, only hardware perf event can be
 964 *              retrieved.
 965 *
 966 *              Also, be aware that the newer helper
 967 *              **bpf_perf_event_read_value**\ () is recommended over
 968 *              **bpf_perf_event_read**\ () in general. The latter has some ABI
 969 *              quirks where error and counter value are used as a return code
 970 *              (which is wrong to do since ranges may overlap). This issue is
 971 *              fixed with **bpf_perf_event_read_value**\ (), which at the same
 972 *              time provides more features over the **bpf_perf_event_read**\
 973 *              () interface. Please refer to the description of
 974 *              **bpf_perf_event_read_value**\ () for details.
 975 *      Return
 976 *              The value of the perf event counter read from the map, or a
 977 *              negative error code in case of failure.
 978 *
 979 * int bpf_redirect(u32 ifindex, u64 flags)
 980 *      Description
 981 *              Redirect the packet to another net device of index *ifindex*.
 982 *              This helper is somewhat similar to **bpf_clone_redirect**\
 983 *              (), except that the packet is not cloned, which provides
 984 *              increased performance.
 985 *
 986 *              Except for XDP, both ingress and egress interfaces can be used
 987 *              for redirection. The **BPF_F_INGRESS** value in *flags* is used
 988 *              to make the distinction (ingress path is selected if the flag
 989 *              is present, egress path otherwise). Currently, XDP only
 990 *              supports redirection to the egress interface, and accepts no
 991 *              flag at all.
 992 *
 993 *              The same effect can be attained with the more generic
 994 *              **bpf_redirect_map**\ (), which requires specific maps to be
 995 *              used but offers better performance.
 996 *      Return
 997 *              For XDP, the helper returns **XDP_REDIRECT** on success or
 998 *              **XDP_ABORTED** on error. For other program types, the values
 999 *              are **TC_ACT_REDIRECT** on success or **TC_ACT_SHOT** on
1000 *              error.
1001 *
1002 * u32 bpf_get_route_realm(struct sk_buff *skb)
1003 *      Description
1004 *              Retrieve the realm or the route, that is to say the
1005 *              **tclassid** field of the destination for the *skb*. The
1006 *              indentifier retrieved is a user-provided tag, similar to the
1007 *              one used with the net_cls cgroup (see description for
1008 *              **bpf_get_cgroup_classid**\ () helper), but here this tag is
1009 *              held by a route (a destination entry), not by a task.
1010 *
1011 *              Retrieving this identifier works with the clsact TC egress hook
1012 *              (see also **tc-bpf(8)**), or alternatively on conventional
1013 *              classful egress qdiscs, but not on TC ingress path. In case of
1014 *              clsact TC egress hook, this has the advantage that, internally,
1015 *              the destination entry has not been dropped yet in the transmit
1016 *              path. Therefore, the destination entry does not need to be
1017 *              artificially held via **netif_keep_dst**\ () for a classful
1018 *              qdisc until the *skb* is freed.
1019 *
1020 *              This helper is available only if the kernel was compiled with
1021 *              **CONFIG_IP_ROUTE_CLASSID** configuration option.
1022 *      Return
1023 *              The realm of the route for the packet associated to *skb*, or 0
1024 *              if none was found.
1025 *
1026 * int bpf_perf_event_output(struct pt_regs *ctx, struct bpf_map *map, u64 flags, void *data, u64 size)
1027 *      Description
1028 *              Write raw *data* blob into a special BPF perf event held by
1029 *              *map* of type **BPF_MAP_TYPE_PERF_EVENT_ARRAY**. This perf
1030 *              event must have the following attributes: **PERF_SAMPLE_RAW**
1031 *              as **sample_type**, **PERF_TYPE_SOFTWARE** as **type**, and
1032 *              **PERF_COUNT_SW_BPF_OUTPUT** as **config**.
1033 *
1034 *              The *flags* are used to indicate the index in *map* for which
1035 *              the value must be put, masked with **BPF_F_INDEX_MASK**.
1036 *              Alternatively, *flags* can be set to **BPF_F_CURRENT_CPU**
1037 *              to indicate that the index of the current CPU core should be
1038 *              used.
1039 *
1040 *              The value to write, of *size*, is passed through eBPF stack and
1041 *              pointed by *data*.
1042 *
1043 *              The context of the program *ctx* needs also be passed to the
1044 *              helper.
1045 *
1046 *              On user space, a program willing to read the values needs to
1047 *              call **perf_event_open**\ () on the perf event (either for
1048 *              one or for all CPUs) and to store the file descriptor into the
1049 *              *map*. This must be done before the eBPF program can send data
1050 *              into it. An example is available in file
1051 *              *samples/bpf/trace_output_user.c* in the Linux kernel source
1052 *              tree (the eBPF program counterpart is in
1053 *              *samples/bpf/trace_output_kern.c*).
1054 *
1055 *              **bpf_perf_event_output**\ () achieves better performance
1056 *              than **bpf_trace_printk**\ () for sharing data with user
1057 *              space, and is much better suitable for streaming data from eBPF
1058 *              programs.
1059 *
1060 *              Note that this helper is not restricted to tracing use cases
1061 *              and can be used with programs attached to TC or XDP as well,
1062 *              where it allows for passing data to user space listeners. Data
1063 *              can be:
1064 *
1065 *              * Only custom structs,
1066 *              * Only the packet payload, or
1067 *              * A combination of both.
1068 *      Return
1069 *              0 on success, or a negative error in case of failure.
1070 *
1071 * int bpf_skb_load_bytes(const struct sk_buff *skb, u32 offset, void *to, u32 len)
1072 *      Description
1073 *              This helper was provided as an easy way to load data from a
1074 *              packet. It can be used to load *len* bytes from *offset* from
1075 *              the packet associated to *skb*, into the buffer pointed by
1076 *              *to*.
1077 *
1078 *              Since Linux 4.7, usage of this helper has mostly been replaced
1079 *              by "direct packet access", enabling packet data to be
1080 *              manipulated with *skb*\ **->data** and *skb*\ **->data_end**
1081 *              pointing respectively to the first byte of packet data and to
1082 *              the byte after the last byte of packet data. However, it
1083 *              remains useful if one wishes to read large quantities of data
1084 *              at once from a packet into the eBPF stack.
1085 *      Return
1086 *              0 on success, or a negative error in case of failure.
1087 *
1088 * int bpf_get_stackid(struct pt_regs *ctx, struct bpf_map *map, u64 flags)
1089 *      Description
1090 *              Walk a user or a kernel stack and return its id. To achieve
1091 *              this, the helper needs *ctx*, which is a pointer to the context
1092 *              on which the tracing program is executed, and a pointer to a
1093 *              *map* of type **BPF_MAP_TYPE_STACK_TRACE**.
1094 *
1095 *              The last argument, *flags*, holds the number of stack frames to
1096 *              skip (from 0 to 255), masked with
1097 *              **BPF_F_SKIP_FIELD_MASK**. The next bits can be used to set
1098 *              a combination of the following flags:
1099 *
1100 *              **BPF_F_USER_STACK**
1101 *                      Collect a user space stack instead of a kernel stack.
1102 *              **BPF_F_FAST_STACK_CMP**
1103 *                      Compare stacks by hash only.
1104 *              **BPF_F_REUSE_STACKID**
1105 *                      If two different stacks hash into the same *stackid*,
1106 *                      discard the old one.
1107 *
1108 *              The stack id retrieved is a 32 bit long integer handle which
1109 *              can be further combined with other data (including other stack
1110 *              ids) and used as a key into maps. This can be useful for
1111 *              generating a variety of graphs (such as flame graphs or off-cpu
1112 *              graphs).
1113 *
1114 *              For walking a stack, this helper is an improvement over
1115 *              **bpf_probe_read**\ (), which can be used with unrolled loops
1116 *              but is not efficient and consumes a lot of eBPF instructions.
1117 *              Instead, **bpf_get_stackid**\ () can collect up to
1118 *              **PERF_MAX_STACK_DEPTH** both kernel and user frames. Note that
1119 *              this limit can be controlled with the **sysctl** program, and
1120 *              that it should be manually increased in order to profile long
1121 *              user stacks (such as stacks for Java programs). To do so, use:
1122 *
1123 *              ::
1124 *
1125 *                      # sysctl kernel.perf_event_max_stack=<new value>
1126 *      Return
1127 *              The positive or null stack id on success, or a negative error
1128 *              in case of failure.
1129 *
1130 * s64 bpf_csum_diff(__be32 *from, u32 from_size, __be32 *to, u32 to_size, __wsum seed)
1131 *      Description
1132 *              Compute a checksum difference, from the raw buffer pointed by
1133 *              *from*, of length *from_size* (that must be a multiple of 4),
1134 *              towards the raw buffer pointed by *to*, of size *to_size*
1135 *              (same remark). An optional *seed* can be added to the value
1136 *              (this can be cascaded, the seed may come from a previous call
1137 *              to the helper).
1138 *
1139 *              This is flexible enough to be used in several ways:
1140 *
1141 *              * With *from_size* == 0, *to_size* > 0 and *seed* set to
1142 *                checksum, it can be used when pushing new data.
1143 *              * With *from_size* > 0, *to_size* == 0 and *seed* set to
1144 *                checksum, it can be used when removing data from a packet.
1145 *              * With *from_size* > 0, *to_size* > 0 and *seed* set to 0, it
1146 *                can be used to compute a diff. Note that *from_size* and
1147 *                *to_size* do not need to be equal.
1148 *
1149 *              This helper can be used in combination with
1150 *              **bpf_l3_csum_replace**\ () and **bpf_l4_csum_replace**\ (), to
1151 *              which one can feed in the difference computed with
1152 *              **bpf_csum_diff**\ ().
1153 *      Return
1154 *              The checksum result, or a negative error code in case of
1155 *              failure.
1156 *
1157 * int bpf_skb_get_tunnel_opt(struct sk_buff *skb, u8 *opt, u32 size)
1158 *      Description
1159 *              Retrieve tunnel options metadata for the packet associated to
1160 *              *skb*, and store the raw tunnel option data to the buffer *opt*
1161 *              of *size*.
1162 *
1163 *              This helper can be used with encapsulation devices that can
1164 *              operate in "collect metadata" mode (please refer to the related
1165 *              note in the description of **bpf_skb_get_tunnel_key**\ () for
1166 *              more details). A particular example where this can be used is
1167 *              in combination with the Geneve encapsulation protocol, where it
1168 *              allows for pushing (with **bpf_skb_get_tunnel_opt**\ () helper)
1169 *              and retrieving arbitrary TLVs (Type-Length-Value headers) from
1170 *              the eBPF program. This allows for full customization of these
1171 *              headers.
1172 *      Return
1173 *              The size of the option data retrieved.
1174 *
1175 * int bpf_skb_set_tunnel_opt(struct sk_buff *skb, u8 *opt, u32 size)
1176 *      Description
1177 *              Set tunnel options metadata for the packet associated to *skb*
1178 *              to the option data contained in the raw buffer *opt* of *size*.
1179 *
1180 *              See also the description of the **bpf_skb_get_tunnel_opt**\ ()
1181 *              helper for additional information.
1182 *      Return
1183 *              0 on success, or a negative error in case of failure.
1184 *
1185 * int bpf_skb_change_proto(struct sk_buff *skb, __be16 proto, u64 flags)
1186 *      Description
1187 *              Change the protocol of the *skb* to *proto*. Currently
1188 *              supported are transition from IPv4 to IPv6, and from IPv6 to
1189 *              IPv4. The helper takes care of the groundwork for the
1190 *              transition, including resizing the socket buffer. The eBPF
1191 *              program is expected to fill the new headers, if any, via
1192 *              **skb_store_bytes**\ () and to recompute the checksums with
1193 *              **bpf_l3_csum_replace**\ () and **bpf_l4_csum_replace**\
1194 *              (). The main case for this helper is to perform NAT64
1195 *              operations out of an eBPF program.
1196 *
1197 *              Internally, the GSO type is marked as dodgy so that headers are
1198 *              checked and segments are recalculated by the GSO/GRO engine.
1199 *              The size for GSO target is adapted as well.
1200 *
1201 *              All values for *flags* are reserved for future usage, and must
1202 *              be left at zero.
1203 *
1204 *              A call to this helper is susceptible to change the underlying
1205 *              packet buffer. Therefore, at load time, all checks on pointers
1206 *              previously done by the verifier are invalidated and must be
1207 *              performed again, if the helper is used in combination with
1208 *              direct packet access.
1209 *      Return
1210 *              0 on success, or a negative error in case of failure.
1211 *
1212 * int bpf_skb_change_type(struct sk_buff *skb, u32 type)
1213 *      Description
1214 *              Change the packet type for the packet associated to *skb*. This
1215 *              comes down to setting *skb*\ **->pkt_type** to *type*, except
1216 *              the eBPF program does not have a write access to *skb*\
1217 *              **->pkt_type** beside this helper. Using a helper here allows
1218 *              for graceful handling of errors.
1219 *
1220 *              The major use case is to change incoming *skb*s to
1221 *              **PACKET_HOST** in a programmatic way instead of having to
1222 *              recirculate via **redirect**\ (..., **BPF_F_INGRESS**), for
1223 *              example.
1224 *
1225 *              Note that *type* only allows certain values. At this time, they
1226 *              are:
1227 *
1228 *              **PACKET_HOST**
1229 *                      Packet is for us.
1230 *              **PACKET_BROADCAST**
1231 *                      Send packet to all.
1232 *              **PACKET_MULTICAST**
1233 *                      Send packet to group.
1234 *              **PACKET_OTHERHOST**
1235 *                      Send packet to someone else.
1236 *      Return
1237 *              0 on success, or a negative error in case of failure.
1238 *
1239 * int bpf_skb_under_cgroup(struct sk_buff *skb, struct bpf_map *map, u32 index)
1240 *      Description
1241 *              Check whether *skb* is a descendant of the cgroup2 held by
1242 *              *map* of type **BPF_MAP_TYPE_CGROUP_ARRAY**, at *index*.
1243 *      Return
1244 *              The return value depends on the result of the test, and can be:
1245 *
1246 *              * 0, if the *skb* failed the cgroup2 descendant test.
1247 *              * 1, if the *skb* succeeded the cgroup2 descendant test.
1248 *              * A negative error code, if an error occurred.
1249 *
1250 * u32 bpf_get_hash_recalc(struct sk_buff *skb)
1251 *      Description
1252 *              Retrieve the hash of the packet, *skb*\ **->hash**. If it is
1253 *              not set, in particular if the hash was cleared due to mangling,
1254 *              recompute this hash. Later accesses to the hash can be done
1255 *              directly with *skb*\ **->hash**.
1256 *
1257 *              Calling **bpf_set_hash_invalid**\ (), changing a packet
1258 *              prototype with **bpf_skb_change_proto**\ (), or calling
1259 *              **bpf_skb_store_bytes**\ () with the
1260 *              **BPF_F_INVALIDATE_HASH** are actions susceptible to clear
1261 *              the hash and to trigger a new computation for the next call to
1262 *              **bpf_get_hash_recalc**\ ().
1263 *      Return
1264 *              The 32-bit hash.
1265 *
1266 * u64 bpf_get_current_task(void)
1267 *      Return
1268 *              A pointer to the current task struct.
1269 *
1270 * int bpf_probe_write_user(void *dst, const void *src, u32 len)
1271 *      Description
1272 *              Attempt in a safe way to write *len* bytes from the buffer
1273 *              *src* to *dst* in memory. It only works for threads that are in
1274 *              user context, and *dst* must be a valid user space address.
1275 *
1276 *              This helper should not be used to implement any kind of
1277 *              security mechanism because of TOC-TOU attacks, but rather to
1278 *              debug, divert, and manipulate execution of semi-cooperative
1279 *              processes.
1280 *
1281 *              Keep in mind that this feature is meant for experiments, and it
1282 *              has a risk of crashing the system and running programs.
1283 *              Therefore, when an eBPF program using this helper is attached,
1284 *              a warning including PID and process name is printed to kernel
1285 *              logs.
1286 *      Return
1287 *              0 on success, or a negative error in case of failure.
1288 *
1289 * int bpf_current_task_under_cgroup(struct bpf_map *map, u32 index)
1290 *      Description
1291 *              Check whether the probe is being run is the context of a given
1292 *              subset of the cgroup2 hierarchy. The cgroup2 to test is held by
1293 *              *map* of type **BPF_MAP_TYPE_CGROUP_ARRAY**, at *index*.
1294 *      Return
1295 *              The return value depends on the result of the test, and can be:
1296 *
1297 *              * 0, if the *skb* task belongs to the cgroup2.
1298 *              * 1, if the *skb* task does not belong to the cgroup2.
1299 *              * A negative error code, if an error occurred.
1300 *
1301 * int bpf_skb_change_tail(struct sk_buff *skb, u32 len, u64 flags)
1302 *      Description
1303 *              Resize (trim or grow) the packet associated to *skb* to the
1304 *              new *len*. The *flags* are reserved for future usage, and must
1305 *              be left at zero.
1306 *
1307 *              The basic idea is that the helper performs the needed work to
1308 *              change the size of the packet, then the eBPF program rewrites
1309 *              the rest via helpers like **bpf_skb_store_bytes**\ (),
1310 *              **bpf_l3_csum_replace**\ (), **bpf_l3_csum_replace**\ ()
1311 *              and others. This helper is a slow path utility intended for
1312 *              replies with control messages. And because it is targeted for
1313 *              slow path, the helper itself can afford to be slow: it
1314 *              implicitly linearizes, unclones and drops offloads from the
1315 *              *skb*.
1316 *
1317 *              A call to this helper is susceptible to change the underlying
1318 *              packet buffer. Therefore, at load time, all checks on pointers
1319 *              previously done by the verifier are invalidated and must be
1320 *              performed again, if the helper is used in combination with
1321 *              direct packet access.
1322 *      Return
1323 *              0 on success, or a negative error in case of failure.
1324 *
1325 * int bpf_skb_pull_data(struct sk_buff *skb, u32 len)
1326 *      Description
1327 *              Pull in non-linear data in case the *skb* is non-linear and not
1328 *              all of *len* are part of the linear section. Make *len* bytes
1329 *              from *skb* readable and writable. If a zero value is passed for
1330 *              *len*, then the whole length of the *skb* is pulled.
1331 *
1332 *              This helper is only needed for reading and writing with direct
1333 *              packet access.
1334 *
1335 *              For direct packet access, testing that offsets to access
1336 *              are within packet boundaries (test on *skb*\ **->data_end**) is
1337 *              susceptible to fail if offsets are invalid, or if the requested
1338 *              data is in non-linear parts of the *skb*. On failure the
1339 *              program can just bail out, or in the case of a non-linear
1340 *              buffer, use a helper to make the data available. The
1341 *              **bpf_skb_load_bytes**\ () helper is a first solution to access
1342 *              the data. Another one consists in using **bpf_skb_pull_data**
1343 *              to pull in once the non-linear parts, then retesting and
1344 *              eventually access the data.
1345 *
1346 *              At the same time, this also makes sure the *skb* is uncloned,
1347 *              which is a necessary condition for direct write. As this needs
1348 *              to be an invariant for the write part only, the verifier
1349 *              detects writes and adds a prologue that is calling
1350 *              **bpf_skb_pull_data()** to effectively unclone the *skb* from
1351 *              the very beginning in case it is indeed cloned.
1352 *
1353 *              A call to this helper is susceptible to change the underlying
1354 *              packet buffer. Therefore, at load time, all checks on pointers
1355 *              previously done by the verifier are invalidated and must be
1356 *              performed again, if the helper is used in combination with
1357 *              direct packet access.
1358 *      Return
1359 *              0 on success, or a negative error in case of failure.
1360 *
1361 * s64 bpf_csum_update(struct sk_buff *skb, __wsum csum)
1362 *      Description
1363 *              Add the checksum *csum* into *skb*\ **->csum** in case the
1364 *              driver has supplied a checksum for the entire packet into that
1365 *              field. Return an error otherwise. This helper is intended to be
1366 *              used in combination with **bpf_csum_diff**\ (), in particular
1367 *              when the checksum needs to be updated after data has been
1368 *              written into the packet through direct packet access.
1369 *      Return
1370 *              The checksum on success, or a negative error code in case of
1371 *              failure.
1372 *
1373 * void bpf_set_hash_invalid(struct sk_buff *skb)
1374 *      Description
1375 *              Invalidate the current *skb*\ **->hash**. It can be used after
1376 *              mangling on headers through direct packet access, in order to
1377 *              indicate that the hash is outdated and to trigger a
1378 *              recalculation the next time the kernel tries to access this
1379 *              hash or when the **bpf_get_hash_recalc**\ () helper is called.
1380 *
1381 * int bpf_get_numa_node_id(void)
1382 *      Description
1383 *              Return the id of the current NUMA node. The primary use case
1384 *              for this helper is the selection of sockets for the local NUMA
1385 *              node, when the program is attached to sockets using the
1386 *              **SO_ATTACH_REUSEPORT_EBPF** option (see also **socket(7)**),
1387 *              but the helper is also available to other eBPF program types,
1388 *              similarly to **bpf_get_smp_processor_id**\ ().
1389 *      Return
1390 *              The id of current NUMA node.
1391 *
1392 * int bpf_skb_change_head(struct sk_buff *skb, u32 len, u64 flags)
1393 *      Description
1394 *              Grows headroom of packet associated to *skb* and adjusts the
1395 *              offset of the MAC header accordingly, adding *len* bytes of
1396 *              space. It automatically extends and reallocates memory as
1397 *              required.
1398 *
1399 *              This helper can be used on a layer 3 *skb* to push a MAC header
1400 *              for redirection into a layer 2 device.
1401 *
1402 *              All values for *flags* are reserved for future usage, and must
1403 *              be left at zero.
1404 *
1405 *              A call to this helper is susceptible to change the underlying
1406 *              packet buffer. Therefore, at load time, all checks on pointers
1407 *              previously done by the verifier are invalidated and must be
1408 *              performed again, if the helper is used in combination with
1409 *              direct packet access.
1410 *      Return
1411 *              0 on success, or a negative error in case of failure.
1412 *
1413 * int bpf_xdp_adjust_head(struct xdp_buff *xdp_md, int delta)
1414 *      Description
1415 *              Adjust (move) *xdp_md*\ **->data** by *delta* bytes. Note that
1416 *              it is possible to use a negative value for *delta*. This helper
1417 *              can be used to prepare the packet for pushing or popping
1418 *              headers.
1419 *
1420 *              A call to this helper is susceptible to change the underlying
1421 *              packet buffer. Therefore, at load time, all checks on pointers
1422 *              previously done by the verifier are invalidated and must be
1423 *              performed again, if the helper is used in combination with
1424 *              direct packet access.
1425 *      Return
1426 *              0 on success, or a negative error in case of failure.
1427 *
1428 * int bpf_probe_read_str(void *dst, int size, const void *unsafe_ptr)
1429 *      Description
1430 *              Copy a NUL terminated string from an unsafe address
1431 *              *unsafe_ptr* to *dst*. The *size* should include the
1432 *              terminating NUL byte. In case the string length is smaller than
1433 *              *size*, the target is not padded with further NUL bytes. If the
1434 *              string length is larger than *size*, just *size*-1 bytes are
1435 *              copied and the last byte is set to NUL.
1436 *
1437 *              On success, the length of the copied string is returned. This
1438 *              makes this helper useful in tracing programs for reading
1439 *              strings, and more importantly to get its length at runtime. See
1440 *              the following snippet:
1441 *
1442 *              ::
1443 *
1444 *                      SEC("kprobe/sys_open")
1445 *                      void bpf_sys_open(struct pt_regs *ctx)
1446 *                      {
1447 *                              char buf[PATHLEN]; // PATHLEN is defined to 256
1448 *                              int res = bpf_probe_read_str(buf, sizeof(buf),
1449 *                                                           ctx->di);
1450 *
1451 *                              // Consume buf, for example push it to
1452 *                              // userspace via bpf_perf_event_output(); we
1453 *                              // can use res (the string length) as event
1454 *                              // size, after checking its boundaries.
1455 *                      }
1456 *
1457 *              In comparison, using **bpf_probe_read()** helper here instead
1458 *              to read the string would require to estimate the length at
1459 *              compile time, and would often result in copying more memory
1460 *              than necessary.
1461 *
1462 *              Another useful use case is when parsing individual process
1463 *              arguments or individual environment variables navigating
1464 *              *current*\ **->mm->arg_start** and *current*\
1465 *              **->mm->env_start**: using this helper and the return value,
1466 *              one can quickly iterate at the right offset of the memory area.
1467 *      Return
1468 *              On success, the strictly positive length of the string,
1469 *              including the trailing NUL character. On error, a negative
1470 *              value.
1471 *
1472 * u64 bpf_get_socket_cookie(struct sk_buff *skb)
1473 *      Description
1474 *              If the **struct sk_buff** pointed by *skb* has a known socket,
1475 *              retrieve the cookie (generated by the kernel) of this socket.
1476 *              If no cookie has been set yet, generate a new cookie. Once
1477 *              generated, the socket cookie remains stable for the life of the
1478 *              socket. This helper can be useful for monitoring per socket
1479 *              networking traffic statistics as it provides a global socket
1480 *              identifier that can be assumed unique.
1481 *      Return
1482 *              A 8-byte long non-decreasing number on success, or 0 if the
1483 *              socket field is missing inside *skb*.
1484 *
1485 * u64 bpf_get_socket_cookie(struct bpf_sock_addr *ctx)
1486 *      Description
1487 *              Equivalent to bpf_get_socket_cookie() helper that accepts
1488 *              *skb*, but gets socket from **struct bpf_sock_addr** context.
1489 *      Return
1490 *              A 8-byte long non-decreasing number.
1491 *
1492 * u64 bpf_get_socket_cookie(struct bpf_sock_ops *ctx)
1493 *      Description
1494 *              Equivalent to bpf_get_socket_cookie() helper that accepts
1495 *              *skb*, but gets socket from **struct bpf_sock_ops** context.
1496 *      Return
1497 *              A 8-byte long non-decreasing number.
1498 *
1499 * u32 bpf_get_socket_uid(struct sk_buff *skb)
1500 *      Return
1501 *              The owner UID of the socket associated to *skb*. If the socket
1502 *              is **NULL**, or if it is not a full socket (i.e. if it is a
1503 *              time-wait or a request socket instead), **overflowuid** value
1504 *              is returned (note that **overflowuid** might also be the actual
1505 *              UID value for the socket).
1506 *
1507 * u32 bpf_set_hash(struct sk_buff *skb, u32 hash)
1508 *      Description
1509 *              Set the full hash for *skb* (set the field *skb*\ **->hash**)
1510 *              to value *hash*.
1511 *      Return
1512 *              0
1513 *
1514 * int bpf_setsockopt(struct bpf_sock_ops *bpf_socket, int level, int optname, char *optval, int optlen)
1515 *      Description
1516 *              Emulate a call to **setsockopt()** on the socket associated to
1517 *              *bpf_socket*, which must be a full socket. The *level* at
1518 *              which the option resides and the name *optname* of the option
1519 *              must be specified, see **setsockopt(2)** for more information.
1520 *              The option value of length *optlen* is pointed by *optval*.
1521 *
1522 *              This helper actually implements a subset of **setsockopt()**.
1523 *              It supports the following *level*\ s:
1524 *
1525 *              * **SOL_SOCKET**, which supports the following *optname*\ s:
1526 *                **SO_RCVBUF**, **SO_SNDBUF**, **SO_MAX_PACING_RATE**,
1527 *                **SO_PRIORITY**, **SO_RCVLOWAT**, **SO_MARK**.
1528 *              * **IPPROTO_TCP**, which supports the following *optname*\ s:
1529 *                **TCP_CONGESTION**, **TCP_BPF_IW**,
1530 *                **TCP_BPF_SNDCWND_CLAMP**.
1531 *              * **IPPROTO_IP**, which supports *optname* **IP_TOS**.
1532 *              * **IPPROTO_IPV6**, which supports *optname* **IPV6_TCLASS**.
1533 *      Return
1534 *              0 on success, or a negative error in case of failure.
1535 *
1536 * int bpf_skb_adjust_room(struct sk_buff *skb, s32 len_diff, u32 mode, u64 flags)
1537 *      Description
1538 *              Grow or shrink the room for data in the packet associated to
1539 *              *skb* by *len_diff*, and according to the selected *mode*.
1540 *
1541 *              There are two supported modes at this time:
1542 *
1543 *              * **BPF_ADJ_ROOM_MAC**: Adjust room at the mac layer
1544 *                (room space is added or removed below the layer 2 header).
1545 *
1546 *              * **BPF_ADJ_ROOM_NET**: Adjust room at the network layer
1547 *                (room space is added or removed below the layer 3 header).
1548 *
1549 *              The following flags are supported at this time:
1550 *
1551 *              * **BPF_F_ADJ_ROOM_FIXED_GSO**: Do not adjust gso_size.
1552 *                Adjusting mss in this way is not allowed for datagrams.
1553 *
1554 *              * **BPF_F_ADJ_ROOM_ENCAP_L3_IPV4**,
1555 *                **BPF_F_ADJ_ROOM_ENCAP_L3_IPV6**:
1556 *                Any new space is reserved to hold a tunnel header.
1557 *                Configure skb offsets and other fields accordingly.
1558 *
1559 *              * **BPF_F_ADJ_ROOM_ENCAP_L4_GRE**,
1560 *                **BPF_F_ADJ_ROOM_ENCAP_L4_UDP**:
1561 *                Use with ENCAP_L3 flags to further specify the tunnel type.
1562 *
1563 *              * **BPF_F_ADJ_ROOM_ENCAP_L2**\ (*len*):
1564 *                Use with ENCAP_L3/L4 flags to further specify the tunnel
1565 *                type; *len* is the length of the inner MAC header.
1566 *
1567 *              A call to this helper is susceptible to change the underlying
1568 *              packet buffer. Therefore, at load time, all checks on pointers
1569 *              previously done by the verifier are invalidated and must be
1570 *              performed again, if the helper is used in combination with
1571 *              direct packet access.
1572 *      Return
1573 *              0 on success, or a negative error in case of failure.
1574 *
1575 * int bpf_redirect_map(struct bpf_map *map, u32 key, u64 flags)
1576 *      Description
1577 *              Redirect the packet to the endpoint referenced by *map* at
1578 *              index *key*. Depending on its type, this *map* can contain
1579 *              references to net devices (for forwarding packets through other
1580 *              ports), or to CPUs (for redirecting XDP frames to another CPU;
1581 *              but this is only implemented for native XDP (with driver
1582 *              support) as of this writing).
1583 *
1584 *              The lower two bits of *flags* are used as the return code if
1585 *              the map lookup fails. This is so that the return value can be
1586 *              one of the XDP program return codes up to XDP_TX, as chosen by
1587 *              the caller. Any higher bits in the *flags* argument must be
1588 *              unset.
1589 *
1590 *              When used to redirect packets to net devices, this helper
1591 *              provides a high performance increase over **bpf_redirect**\ ().
1592 *              This is due to various implementation details of the underlying
1593 *              mechanisms, one of which is the fact that **bpf_redirect_map**\
1594 *              () tries to send packet as a "bulk" to the device.
1595 *      Return
1596 *              **XDP_REDIRECT** on success, or **XDP_ABORTED** on error.
1597 *
1598 * int bpf_sk_redirect_map(struct bpf_map *map, u32 key, u64 flags)
1599 *      Description
1600 *              Redirect the packet to the socket referenced by *map* (of type
1601 *              **BPF_MAP_TYPE_SOCKMAP**) at index *key*. Both ingress and
1602 *              egress interfaces can be used for redirection. The
1603 *              **BPF_F_INGRESS** value in *flags* is used to make the
1604 *              distinction (ingress path is selected if the flag is present,
1605 *              egress path otherwise). This is the only flag supported for now.
1606 *      Return
1607 *              **SK_PASS** on success, or **SK_DROP** on error.
1608 *
1609 * int bpf_sock_map_update(struct bpf_sock_ops *skops, struct bpf_map *map, void *key, u64 flags)
1610 *      Description
1611 *              Add an entry to, or update a *map* referencing sockets. The
1612 *              *skops* is used as a new value for the entry associated to
1613 *              *key*. *flags* is one of:
1614 *
1615 *              **BPF_NOEXIST**
1616 *                      The entry for *key* must not exist in the map.
1617 *              **BPF_EXIST**
1618 *                      The entry for *key* must already exist in the map.
1619 *              **BPF_ANY**
1620 *                      No condition on the existence of the entry for *key*.
1621 *
1622 *              If the *map* has eBPF programs (parser and verdict), those will
1623 *              be inherited by the socket being added. If the socket is
1624 *              already attached to eBPF programs, this results in an error.
1625 *      Return
1626 *              0 on success, or a negative error in case of failure.
1627 *
1628 * int bpf_xdp_adjust_meta(struct xdp_buff *xdp_md, int delta)
1629 *      Description
1630 *              Adjust the address pointed by *xdp_md*\ **->data_meta** by
1631 *              *delta* (which can be positive or negative). Note that this
1632 *              operation modifies the address stored in *xdp_md*\ **->data**,
1633 *              so the latter must be loaded only after the helper has been
1634 *              called.
1635 *
1636 *              The use of *xdp_md*\ **->data_meta** is optional and programs
1637 *              are not required to use it. The rationale is that when the
1638 *              packet is processed with XDP (e.g. as DoS filter), it is
1639 *              possible to push further meta data along with it before passing
1640 *              to the stack, and to give the guarantee that an ingress eBPF
1641 *              program attached as a TC classifier on the same device can pick
1642 *              this up for further post-processing. Since TC works with socket
1643 *              buffers, it remains possible to set from XDP the **mark** or
1644 *              **priority** pointers, or other pointers for the socket buffer.
1645 *              Having this scratch space generic and programmable allows for
1646 *              more flexibility as the user is free to store whatever meta
1647 *              data they need.
1648 *
1649 *              A call to this helper is susceptible to change the underlying
1650 *              packet buffer. Therefore, at load time, all checks on pointers
1651 *              previously done by the verifier are invalidated and must be
1652 *              performed again, if the helper is used in combination with
1653 *              direct packet access.
1654 *      Return
1655 *              0 on success, or a negative error in case of failure.
1656 *
1657 * int bpf_perf_event_read_value(struct bpf_map *map, u64 flags, struct bpf_perf_event_value *buf, u32 buf_size)
1658 *      Description
1659 *              Read the value of a perf event counter, and store it into *buf*
1660 *              of size *buf_size*. This helper relies on a *map* of type
1661 *              **BPF_MAP_TYPE_PERF_EVENT_ARRAY**. The nature of the perf event
1662 *              counter is selected when *map* is updated with perf event file
1663 *              descriptors. The *map* is an array whose size is the number of
1664 *              available CPUs, and each cell contains a value relative to one
1665 *              CPU. The value to retrieve is indicated by *flags*, that
1666 *              contains the index of the CPU to look up, masked with
1667 *              **BPF_F_INDEX_MASK**. Alternatively, *flags* can be set to
1668 *              **BPF_F_CURRENT_CPU** to indicate that the value for the
1669 *              current CPU should be retrieved.
1670 *
1671 *              This helper behaves in a way close to
1672 *              **bpf_perf_event_read**\ () helper, save that instead of
1673 *              just returning the value observed, it fills the *buf*
1674 *              structure. This allows for additional data to be retrieved: in
1675 *              particular, the enabled and running times (in *buf*\
1676 *              **->enabled** and *buf*\ **->running**, respectively) are
1677 *              copied. In general, **bpf_perf_event_read_value**\ () is
1678 *              recommended over **bpf_perf_event_read**\ (), which has some
1679 *              ABI issues and provides fewer functionalities.
1680 *
1681 *              These values are interesting, because hardware PMU (Performance
1682 *              Monitoring Unit) counters are limited resources. When there are
1683 *              more PMU based perf events opened than available counters,
1684 *              kernel will multiplex these events so each event gets certain
1685 *              percentage (but not all) of the PMU time. In case that
1686 *              multiplexing happens, the number of samples or counter value
1687 *              will not reflect the case compared to when no multiplexing
1688 *              occurs. This makes comparison between different runs difficult.
1689 *              Typically, the counter value should be normalized before
1690 *              comparing to other experiments. The usual normalization is done
1691 *              as follows.
1692 *
1693 *              ::
1694 *
1695 *                      normalized_counter = counter * t_enabled / t_running
1696 *
1697 *              Where t_enabled is the time enabled for event and t_running is
1698 *              the time running for event since last normalization. The
1699 *              enabled and running times are accumulated since the perf event
1700 *              open. To achieve scaling factor between two invocations of an
1701 *              eBPF program, users can can use CPU id as the key (which is
1702 *              typical for perf array usage model) to remember the previous
1703 *              value and do the calculation inside the eBPF program.
1704 *      Return
1705 *              0 on success, or a negative error in case of failure.
1706 *
1707 * int bpf_perf_prog_read_value(struct bpf_perf_event_data *ctx, struct bpf_perf_event_value *buf, u32 buf_size)
1708 *      Description
1709 *              For en eBPF program attached to a perf event, retrieve the
1710 *              value of the event counter associated to *ctx* and store it in
1711 *              the structure pointed by *buf* and of size *buf_size*. Enabled
1712 *              and running times are also stored in the structure (see
1713 *              description of helper **bpf_perf_event_read_value**\ () for
1714 *              more details).
1715 *      Return
1716 *              0 on success, or a negative error in case of failure.
1717 *
1718 * int bpf_getsockopt(struct bpf_sock_ops *bpf_socket, int level, int optname, char *optval, int optlen)
1719 *      Description
1720 *              Emulate a call to **getsockopt()** on the socket associated to
1721 *              *bpf_socket*, which must be a full socket. The *level* at
1722 *              which the option resides and the name *optname* of the option
1723 *              must be specified, see **getsockopt(2)** for more information.
1724 *              The retrieved value is stored in the structure pointed by
1725 *              *opval* and of length *optlen*.
1726 *
1727 *              This helper actually implements a subset of **getsockopt()**.
1728 *              It supports the following *level*\ s:
1729 *
1730 *              * **IPPROTO_TCP**, which supports *optname*
1731 *                **TCP_CONGESTION**.
1732 *              * **IPPROTO_IP**, which supports *optname* **IP_TOS**.
1733 *              * **IPPROTO_IPV6**, which supports *optname* **IPV6_TCLASS**.
1734 *      Return
1735 *              0 on success, or a negative error in case of failure.
1736 *
1737 * int bpf_override_return(struct pt_regs *regs, u64 rc)
1738 *      Description
1739 *              Used for error injection, this helper uses kprobes to override
1740 *              the return value of the probed function, and to set it to *rc*.
1741 *              The first argument is the context *regs* on which the kprobe
1742 *              works.
1743 *
1744 *              This helper works by setting setting the PC (program counter)
1745 *              to an override function which is run in place of the original
1746 *              probed function. This means the probed function is not run at
1747 *              all. The replacement function just returns with the required
1748 *              value.
1749 *
1750 *              This helper has security implications, and thus is subject to
1751 *              restrictions. It is only available if the kernel was compiled
1752 *              with the **CONFIG_BPF_KPROBE_OVERRIDE** configuration
1753 *              option, and in this case it only works on functions tagged with
1754 *              **ALLOW_ERROR_INJECTION** in the kernel code.
1755 *
1756 *              Also, the helper is only available for the architectures having
1757 *              the CONFIG_FUNCTION_ERROR_INJECTION option. As of this writing,
1758 *              x86 architecture is the only one to support this feature.
1759 *      Return
1760 *              0
1761 *
1762 * int bpf_sock_ops_cb_flags_set(struct bpf_sock_ops *bpf_sock, int argval)
1763 *      Description
1764 *              Attempt to set the value of the **bpf_sock_ops_cb_flags** field
1765 *              for the full TCP socket associated to *bpf_sock_ops* to
1766 *              *argval*.
1767 *
1768 *              The primary use of this field is to determine if there should
1769 *              be calls to eBPF programs of type
1770 *              **BPF_PROG_TYPE_SOCK_OPS** at various points in the TCP
1771 *              code. A program of the same type can change its value, per
1772 *              connection and as necessary, when the connection is
1773 *              established. This field is directly accessible for reading, but
1774 *              this helper must be used for updates in order to return an
1775 *              error if an eBPF program tries to set a callback that is not
1776 *              supported in the current kernel.
1777 *
1778 *              *argval* is a flag array which can combine these flags:
1779 *
1780 *              * **BPF_SOCK_OPS_RTO_CB_FLAG** (retransmission time out)
1781 *              * **BPF_SOCK_OPS_RETRANS_CB_FLAG** (retransmission)
1782 *              * **BPF_SOCK_OPS_STATE_CB_FLAG** (TCP state change)
1783 *              * **BPF_SOCK_OPS_RTT_CB_FLAG** (every RTT)
1784 *
1785 *              Therefore, this function can be used to clear a callback flag by
1786 *              setting the appropriate bit to zero. e.g. to disable the RTO
1787 *              callback:
1788 *
1789 *              **bpf_sock_ops_cb_flags_set(bpf_sock,**
1790 *                      **bpf_sock->bpf_sock_ops_cb_flags & ~BPF_SOCK_OPS_RTO_CB_FLAG)**
1791 *
1792 *              Here are some examples of where one could call such eBPF
1793 *              program:
1794 *
1795 *              * When RTO fires.
1796 *              * When a packet is retransmitted.
1797 *              * When the connection terminates.
1798 *              * When a packet is sent.
1799 *              * When a packet is received.
1800 *      Return
1801 *              Code **-EINVAL** if the socket is not a full TCP socket;
1802 *              otherwise, a positive number containing the bits that could not
1803 *              be set is returned (which comes down to 0 if all bits were set
1804 *              as required).
1805 *
1806 * int bpf_msg_redirect_map(struct sk_msg_buff *msg, struct bpf_map *map, u32 key, u64 flags)
1807 *      Description
1808 *              This helper is used in programs implementing policies at the
1809 *              socket level. If the message *msg* is allowed to pass (i.e. if
1810 *              the verdict eBPF program returns **SK_PASS**), redirect it to
1811 *              the socket referenced by *map* (of type
1812 *              **BPF_MAP_TYPE_SOCKMAP**) at index *key*. Both ingress and
1813 *              egress interfaces can be used for redirection. The
1814 *              **BPF_F_INGRESS** value in *flags* is used to make the
1815 *              distinction (ingress path is selected if the flag is present,
1816 *              egress path otherwise). This is the only flag supported for now.
1817 *      Return
1818 *              **SK_PASS** on success, or **SK_DROP** on error.
1819 *
1820 * int bpf_msg_apply_bytes(struct sk_msg_buff *msg, u32 bytes)
1821 *      Description
1822 *              For socket policies, apply the verdict of the eBPF program to
1823 *              the next *bytes* (number of bytes) of message *msg*.
1824 *
1825 *              For example, this helper can be used in the following cases:
1826 *
1827 *              * A single **sendmsg**\ () or **sendfile**\ () system call
1828 *                contains multiple logical messages that the eBPF program is
1829 *                supposed to read and for which it should apply a verdict.
1830 *              * An eBPF program only cares to read the first *bytes* of a
1831 *                *msg*. If the message has a large payload, then setting up
1832 *                and calling the eBPF program repeatedly for all bytes, even
1833 *                though the verdict is already known, would create unnecessary
1834 *                overhead.
1835 *
1836 *              When called from within an eBPF program, the helper sets a
1837 *              counter internal to the BPF infrastructure, that is used to
1838 *              apply the last verdict to the next *bytes*. If *bytes* is
1839 *              smaller than the current data being processed from a
1840 *              **sendmsg**\ () or **sendfile**\ () system call, the first
1841 *              *bytes* will be sent and the eBPF program will be re-run with
1842 *              the pointer for start of data pointing to byte number *bytes*
1843 *              **+ 1**. If *bytes* is larger than the current data being
1844 *              processed, then the eBPF verdict will be applied to multiple
1845 *              **sendmsg**\ () or **sendfile**\ () calls until *bytes* are
1846 *              consumed.
1847 *
1848 *              Note that if a socket closes with the internal counter holding
1849 *              a non-zero value, this is not a problem because data is not
1850 *              being buffered for *bytes* and is sent as it is received.
1851 *      Return
1852 *              0
1853 *
1854 * int bpf_msg_cork_bytes(struct sk_msg_buff *msg, u32 bytes)
1855 *      Description
1856 *              For socket policies, prevent the execution of the verdict eBPF
1857 *              program for message *msg* until *bytes* (byte number) have been
1858 *              accumulated.
1859 *
1860 *              This can be used when one needs a specific number of bytes
1861 *              before a verdict can be assigned, even if the data spans
1862 *              multiple **sendmsg**\ () or **sendfile**\ () calls. The extreme
1863 *              case would be a user calling **sendmsg**\ () repeatedly with
1864 *              1-byte long message segments. Obviously, this is bad for
1865 *              performance, but it is still valid. If the eBPF program needs
1866 *              *bytes* bytes to validate a header, this helper can be used to
1867 *              prevent the eBPF program to be called again until *bytes* have
1868 *              been accumulated.
1869 *      Return
1870 *              0
1871 *
1872 * int bpf_msg_pull_data(struct sk_msg_buff *msg, u32 start, u32 end, u64 flags)
1873 *      Description
1874 *              For socket policies, pull in non-linear data from user space
1875 *              for *msg* and set pointers *msg*\ **->data** and *msg*\
1876 *              **->data_end** to *start* and *end* bytes offsets into *msg*,
1877 *              respectively.
1878 *
1879 *              If a program of type **BPF_PROG_TYPE_SK_MSG** is run on a
1880 *              *msg* it can only parse data that the (**data**, **data_end**)
1881 *              pointers have already consumed. For **sendmsg**\ () hooks this
1882 *              is likely the first scatterlist element. But for calls relying
1883 *              on the **sendpage** handler (e.g. **sendfile**\ ()) this will
1884 *              be the range (**0**, **0**) because the data is shared with
1885 *              user space and by default the objective is to avoid allowing
1886 *              user space to modify data while (or after) eBPF verdict is
1887 *              being decided. This helper can be used to pull in data and to
1888 *              set the start and end pointer to given values. Data will be
1889 *              copied if necessary (i.e. if data was not linear and if start
1890 *              and end pointers do not point to the same chunk).
1891 *
1892 *              A call to this helper is susceptible to change the underlying
1893 *              packet buffer. Therefore, at load time, all checks on pointers
1894 *              previously done by the verifier are invalidated and must be
1895 *              performed again, if the helper is used in combination with
1896 *              direct packet access.
1897 *
1898 *              All values for *flags* are reserved for future usage, and must
1899 *              be left at zero.
1900 *      Return
1901 *              0 on success, or a negative error in case of failure.
1902 *
1903 * int bpf_bind(struct bpf_sock_addr *ctx, struct sockaddr *addr, int addr_len)
1904 *      Description
1905 *              Bind the socket associated to *ctx* to the address pointed by
1906 *              *addr*, of length *addr_len*. This allows for making outgoing
1907 *              connection from the desired IP address, which can be useful for
1908 *              example when all processes inside a cgroup should use one
1909 *              single IP address on a host that has multiple IP configured.
1910 *
1911 *              This helper works for IPv4 and IPv6, TCP and UDP sockets. The
1912 *              domain (*addr*\ **->sa_family**) must be **AF_INET** (or
1913 *              **AF_INET6**). Looking for a free port to bind to can be
1914 *              expensive, therefore binding to port is not permitted by the
1915 *              helper: *addr*\ **->sin_port** (or **sin6_port**, respectively)
1916 *              must be set to zero.
1917 *      Return
1918 *              0 on success, or a negative error in case of failure.
1919 *
1920 * int bpf_xdp_adjust_tail(struct xdp_buff *xdp_md, int delta)
1921 *      Description
1922 *              Adjust (move) *xdp_md*\ **->data_end** by *delta* bytes. It is
1923 *              only possible to shrink the packet as of this writing,
1924 *              therefore *delta* must be a negative integer.
1925 *
1926 *              A call to this helper is susceptible to change the underlying
1927 *              packet buffer. Therefore, at load time, all checks on pointers
1928 *              previously done by the verifier are invalidated and must be
1929 *              performed again, if the helper is used in combination with
1930 *              direct packet access.
1931 *      Return
1932 *              0 on success, or a negative error in case of failure.
1933 *
1934 * int bpf_skb_get_xfrm_state(struct sk_buff *skb, u32 index, struct bpf_xfrm_state *xfrm_state, u32 size, u64 flags)
1935 *      Description
1936 *              Retrieve the XFRM state (IP transform framework, see also
1937 *              **ip-xfrm(8)**) at *index* in XFRM "security path" for *skb*.
1938 *
1939 *              The retrieved value is stored in the **struct bpf_xfrm_state**
1940 *              pointed by *xfrm_state* and of length *size*.
1941 *
1942 *              All values for *flags* are reserved for future usage, and must
1943 *              be left at zero.
1944 *
1945 *              This helper is available only if the kernel was compiled with
1946 *              **CONFIG_XFRM** configuration option.
1947 *      Return
1948 *              0 on success, or a negative error in case of failure.
1949 *
1950 * int bpf_get_stack(struct pt_regs *regs, void *buf, u32 size, u64 flags)
1951 *      Description
1952 *              Return a user or a kernel stack in bpf program provided buffer.
1953 *              To achieve this, the helper needs *ctx*, which is a pointer
1954 *              to the context on which the tracing program is executed.
1955 *              To store the stacktrace, the bpf program provides *buf* with
1956 *              a nonnegative *size*.
1957 *
1958 *              The last argument, *flags*, holds the number of stack frames to
1959 *              skip (from 0 to 255), masked with
1960 *              **BPF_F_SKIP_FIELD_MASK**. The next bits can be used to set
1961 *              the following flags:
1962 *
1963 *              **BPF_F_USER_STACK**
1964 *                      Collect a user space stack instead of a kernel stack.
1965 *              **BPF_F_USER_BUILD_ID**
1966 *                      Collect buildid+offset instead of ips for user stack,
1967 *                      only valid if **BPF_F_USER_STACK** is also specified.
1968 *
1969 *              **bpf_get_stack**\ () can collect up to
1970 *              **PERF_MAX_STACK_DEPTH** both kernel and user frames, subject
1971 *              to sufficient large buffer size. Note that
1972 *              this limit can be controlled with the **sysctl** program, and
1973 *              that it should be manually increased in order to profile long
1974 *              user stacks (such as stacks for Java programs). To do so, use:
1975 *
1976 *              ::
1977 *
1978 *                      # sysctl kernel.perf_event_max_stack=<new value>
1979 *      Return
1980 *              A non-negative value equal to or less than *size* on success,
1981 *              or a negative error in case of failure.
1982 *
1983 * int bpf_skb_load_bytes_relative(const struct sk_buff *skb, u32 offset, void *to, u32 len, u32 start_header)
1984 *      Description
1985 *              This helper is similar to **bpf_skb_load_bytes**\ () in that
1986 *              it provides an easy way to load *len* bytes from *offset*
1987 *              from the packet associated to *skb*, into the buffer pointed
1988 *              by *to*. The difference to **bpf_skb_load_bytes**\ () is that
1989 *              a fifth argument *start_header* exists in order to select a
1990 *              base offset to start from. *start_header* can be one of:
1991 *
1992 *              **BPF_HDR_START_MAC**
1993 *                      Base offset to load data from is *skb*'s mac header.
1994 *              **BPF_HDR_START_NET**
1995 *                      Base offset to load data from is *skb*'s network header.
1996 *
1997 *              In general, "direct packet access" is the preferred method to
1998 *              access packet data, however, this helper is in particular useful
1999 *              in socket filters where *skb*\ **->data** does not always point
2000 *              to the start of the mac header and where "direct packet access"
2001 *              is not available.
2002 *      Return
2003 *              0 on success, or a negative error in case of failure.
2004 *
2005 * int bpf_fib_lookup(void *ctx, struct bpf_fib_lookup *params, int plen, u32 flags)
2006 *      Description
2007 *              Do FIB lookup in kernel tables using parameters in *params*.
2008 *              If lookup is successful and result shows packet is to be
2009 *              forwarded, the neighbor tables are searched for the nexthop.
2010 *              If successful (ie., FIB lookup shows forwarding and nexthop
2011 *              is resolved), the nexthop address is returned in ipv4_dst
2012 *              or ipv6_dst based on family, smac is set to mac address of
2013 *              egress device, dmac is set to nexthop mac address, rt_metric
2014 *              is set to metric from route (IPv4/IPv6 only), and ifindex
2015 *              is set to the device index of the nexthop from the FIB lookup.
2016 *
2017 *              *plen* argument is the size of the passed in struct.
2018 *              *flags* argument can be a combination of one or more of the
2019 *              following values:
2020 *
2021 *              **BPF_FIB_LOOKUP_DIRECT**
2022 *                      Do a direct table lookup vs full lookup using FIB
2023 *                      rules.
2024 *              **BPF_FIB_LOOKUP_OUTPUT**
2025 *                      Perform lookup from an egress perspective (default is
2026 *                      ingress).
2027 *
2028 *              *ctx* is either **struct xdp_md** for XDP programs or
2029 *              **struct sk_buff** tc cls_act programs.
2030 *      Return
2031 *              * < 0 if any input argument is invalid
2032 *              *   0 on success (packet is forwarded, nexthop neighbor exists)
2033 *              * > 0 one of **BPF_FIB_LKUP_RET_** codes explaining why the
2034 *                packet is not forwarded or needs assist from full stack
2035 *
2036 * int bpf_sock_hash_update(struct bpf_sock_ops_kern *skops, struct bpf_map *map, void *key, u64 flags)
2037 *      Description
2038 *              Add an entry to, or update a sockhash *map* referencing sockets.
2039 *              The *skops* is used as a new value for the entry associated to
2040 *              *key*. *flags* is one of:
2041 *
2042 *              **BPF_NOEXIST**
2043 *                      The entry for *key* must not exist in the map.
2044 *              **BPF_EXIST**
2045 *                      The entry for *key* must already exist in the map.
2046 *              **BPF_ANY**
2047 *                      No condition on the existence of the entry for *key*.
2048 *
2049 *              If the *map* has eBPF programs (parser and verdict), those will
2050 *              be inherited by the socket being added. If the socket is
2051 *              already attached to eBPF programs, this results in an error.
2052 *      Return
2053 *              0 on success, or a negative error in case of failure.
2054 *
2055 * int bpf_msg_redirect_hash(struct sk_msg_buff *msg, struct bpf_map *map, void *key, u64 flags)
2056 *      Description
2057 *              This helper is used in programs implementing policies at the
2058 *              socket level. If the message *msg* is allowed to pass (i.e. if
2059 *              the verdict eBPF program returns **SK_PASS**), redirect it to
2060 *              the socket referenced by *map* (of type
2061 *              **BPF_MAP_TYPE_SOCKHASH**) using hash *key*. Both ingress and
2062 *              egress interfaces can be used for redirection. The
2063 *              **BPF_F_INGRESS** value in *flags* is used to make the
2064 *              distinction (ingress path is selected if the flag is present,
2065 *              egress path otherwise). This is the only flag supported for now.
2066 *      Return
2067 *              **SK_PASS** on success, or **SK_DROP** on error.
2068 *
2069 * int bpf_sk_redirect_hash(struct sk_buff *skb, struct bpf_map *map, void *key, u64 flags)
2070 *      Description
2071 *              This helper is used in programs implementing policies at the
2072 *              skb socket level. If the sk_buff *skb* is allowed to pass (i.e.
2073 *              if the verdeict eBPF program returns **SK_PASS**), redirect it
2074 *              to the socket referenced by *map* (of type
2075 *              **BPF_MAP_TYPE_SOCKHASH**) using hash *key*. Both ingress and
2076 *              egress interfaces can be used for redirection. The
2077 *              **BPF_F_INGRESS** value in *flags* is used to make the
2078 *              distinction (ingress path is selected if the flag is present,
2079 *              egress otherwise). This is the only flag supported for now.
2080 *      Return
2081 *              **SK_PASS** on success, or **SK_DROP** on error.
2082 *
2083 * int bpf_lwt_push_encap(struct sk_buff *skb, u32 type, void *hdr, u32 len)
2084 *      Description
2085 *              Encapsulate the packet associated to *skb* within a Layer 3
2086 *              protocol header. This header is provided in the buffer at
2087 *              address *hdr*, with *len* its size in bytes. *type* indicates
2088 *              the protocol of the header and can be one of:
2089 *
2090 *              **BPF_LWT_ENCAP_SEG6**
2091 *                      IPv6 encapsulation with Segment Routing Header
2092 *                      (**struct ipv6_sr_hdr**). *hdr* only contains the SRH,
2093 *                      the IPv6 header is computed by the kernel.
2094 *              **BPF_LWT_ENCAP_SEG6_INLINE**
2095 *                      Only works if *skb* contains an IPv6 packet. Insert a
2096 *                      Segment Routing Header (**struct ipv6_sr_hdr**) inside
2097 *                      the IPv6 header.
2098 *              **BPF_LWT_ENCAP_IP**
2099 *                      IP encapsulation (GRE/GUE/IPIP/etc). The outer header
2100 *                      must be IPv4 or IPv6, followed by zero or more
2101 *                      additional headers, up to **LWT_BPF_MAX_HEADROOM**
2102 *                      total bytes in all prepended headers. Please note that
2103 *                      if **skb_is_gso**\ (*skb*) is true, no more than two
2104 *                      headers can be prepended, and the inner header, if
2105 *                      present, should be either GRE or UDP/GUE.
2106 *
2107 *              **BPF_LWT_ENCAP_SEG6**\ \* types can be called by BPF programs
2108 *              of type **BPF_PROG_TYPE_LWT_IN**; **BPF_LWT_ENCAP_IP** type can
2109 *              be called by bpf programs of types **BPF_PROG_TYPE_LWT_IN** and
2110 *              **BPF_PROG_TYPE_LWT_XMIT**.
2111 *
2112 *              A call to this helper is susceptible to change the underlying
2113 *              packet buffer. Therefore, at load time, all checks on pointers
2114 *              previously done by the verifier are invalidated and must be
2115 *              performed again, if the helper is used in combination with
2116 *              direct packet access.
2117 *      Return
2118 *              0 on success, or a negative error in case of failure.
2119 *
2120 * int bpf_lwt_seg6_store_bytes(struct sk_buff *skb, u32 offset, const void *from, u32 len)
2121 *      Description
2122 *              Store *len* bytes from address *from* into the packet
2123 *              associated to *skb*, at *offset*. Only the flags, tag and TLVs
2124 *              inside the outermost IPv6 Segment Routing Header can be
2125 *              modified through this helper.
2126 *
2127 *              A call to this helper is susceptible to change the underlying
2128 *              packet buffer. Therefore, at load time, all checks on pointers
2129 *              previously done by the verifier are invalidated and must be
2130 *              performed again, if the helper is used in combination with
2131 *              direct packet access.
2132 *      Return
2133 *              0 on success, or a negative error in case of failure.
2134 *
2135 * int bpf_lwt_seg6_adjust_srh(struct sk_buff *skb, u32 offset, s32 delta)
2136 *      Description
2137 *              Adjust the size allocated to TLVs in the outermost IPv6
2138 *              Segment Routing Header contained in the packet associated to
2139 *              *skb*, at position *offset* by *delta* bytes. Only offsets
2140 *              after the segments are accepted. *delta* can be as well
2141 *              positive (growing) as negative (shrinking).
2142 *
2143 *              A call to this helper is susceptible to change the underlying
2144 *              packet buffer. Therefore, at load time, all checks on pointers
2145 *              previously done by the verifier are invalidated and must be
2146 *              performed again, if the helper is used in combination with
2147 *              direct packet access.
2148 *      Return
2149 *              0 on success, or a negative error in case of failure.
2150 *
2151 * int bpf_lwt_seg6_action(struct sk_buff *skb, u32 action, void *param, u32 param_len)
2152 *      Description
2153 *              Apply an IPv6 Segment Routing action of type *action* to the
2154 *              packet associated to *skb*. Each action takes a parameter
2155 *              contained at address *param*, and of length *param_len* bytes.
2156 *              *action* can be one of:
2157 *
2158 *              **SEG6_LOCAL_ACTION_END_X**
2159 *                      End.X action: Endpoint with Layer-3 cross-connect.
2160 *                      Type of *param*: **struct in6_addr**.
2161 *              **SEG6_LOCAL_ACTION_END_T**
2162 *                      End.T action: Endpoint with specific IPv6 table lookup.
2163 *                      Type of *param*: **int**.
2164 *              **SEG6_LOCAL_ACTION_END_B6**
2165 *                      End.B6 action: Endpoint bound to an SRv6 policy.
2166 *                      Type of *param*: **struct ipv6_sr_hdr**.
2167 *              **SEG6_LOCAL_ACTION_END_B6_ENCAP**
2168 *                      End.B6.Encap action: Endpoint bound to an SRv6
2169 *                      encapsulation policy.
2170 *                      Type of *param*: **struct ipv6_sr_hdr**.
2171 *
2172 *              A call to this helper is susceptible to change the underlying
2173 *              packet buffer. Therefore, at load time, all checks on pointers
2174 *              previously done by the verifier are invalidated and must be
2175 *              performed again, if the helper is used in combination with
2176 *              direct packet access.
2177 *      Return
2178 *              0 on success, or a negative error in case of failure.
2179 *
2180 * int bpf_rc_repeat(void *ctx)
2181 *      Description
2182 *              This helper is used in programs implementing IR decoding, to
2183 *              report a successfully decoded repeat key message. This delays
2184 *              the generation of a key up event for previously generated
2185 *              key down event.
2186 *
2187 *              Some IR protocols like NEC have a special IR message for
2188 *              repeating last button, for when a button is held down.
2189 *
2190 *              The *ctx* should point to the lirc sample as passed into
2191 *              the program.
2192 *
2193 *              This helper is only available is the kernel was compiled with
2194 *              the **CONFIG_BPF_LIRC_MODE2** configuration option set to
2195 *              "**y**".
2196 *      Return
2197 *              0
2198 *
2199 * int bpf_rc_keydown(void *ctx, u32 protocol, u64 scancode, u32 toggle)
2200 *      Description
2201 *              This helper is used in programs implementing IR decoding, to
2202 *              report a successfully decoded key press with *scancode*,
2203 *              *toggle* value in the given *protocol*. The scancode will be
2204 *              translated to a keycode using the rc keymap, and reported as
2205 *              an input key down event. After a period a key up event is
2206 *              generated. This period can be extended by calling either
2207 *              **bpf_rc_keydown**\ () again with the same values, or calling
2208 *              **bpf_rc_repeat**\ ().
2209 *
2210 *              Some protocols include a toggle bit, in case the button was
2211 *              released and pressed again between consecutive scancodes.
2212 *
2213 *              The *ctx* should point to the lirc sample as passed into
2214 *              the program.
2215 *
2216 *              The *protocol* is the decoded protocol number (see
2217 *              **enum rc_proto** for some predefined values).
2218 *
2219 *              This helper is only available is the kernel was compiled with
2220 *              the **CONFIG_BPF_LIRC_MODE2** configuration option set to
2221 *              "**y**".
2222 *      Return
2223 *              0
2224 *
2225 * u64 bpf_skb_cgroup_id(struct sk_buff *skb)
2226 *      Description
2227 *              Return the cgroup v2 id of the socket associated with the *skb*.
2228 *              This is roughly similar to the **bpf_get_cgroup_classid**\ ()
2229 *              helper for cgroup v1 by providing a tag resp. identifier that
2230 *              can be matched on or used for map lookups e.g. to implement
2231 *              policy. The cgroup v2 id of a given path in the hierarchy is
2232 *              exposed in user space through the f_handle API in order to get
2233 *              to the same 64-bit id.
2234 *
2235 *              This helper can be used on TC egress path, but not on ingress,
2236 *              and is available only if the kernel was compiled with the
2237 *              **CONFIG_SOCK_CGROUP_DATA** configuration option.
2238 *      Return
2239 *              The id is returned or 0 in case the id could not be retrieved.
2240 *
2241 * u64 bpf_get_current_cgroup_id(void)
2242 *      Return
2243 *              A 64-bit integer containing the current cgroup id based
2244 *              on the cgroup within which the current task is running.
2245 *
2246 * void *bpf_get_local_storage(void *map, u64 flags)
2247 *      Description
2248 *              Get the pointer to the local storage area.
2249 *              The type and the size of the local storage is defined
2250 *              by the *map* argument.
2251 *              The *flags* meaning is specific for each map type,
2252 *              and has to be 0 for cgroup local storage.
2253 *
2254 *              Depending on the BPF program type, a local storage area
2255 *              can be shared between multiple instances of the BPF program,
2256 *              running simultaneously.
2257 *
2258 *              A user should care about the synchronization by himself.
2259 *              For example, by using the **BPF_STX_XADD** instruction to alter
2260 *              the shared data.
2261 *      Return
2262 *              A pointer to the local storage area.
2263 *
2264 * int bpf_sk_select_reuseport(struct sk_reuseport_md *reuse, struct bpf_map *map, void *key, u64 flags)
2265 *      Description
2266 *              Select a **SO_REUSEPORT** socket from a
2267 *              **BPF_MAP_TYPE_REUSEPORT_ARRAY** *map*.
2268 *              It checks the selected socket is matching the incoming
2269 *              request in the socket buffer.
2270 *      Return
2271 *              0 on success, or a negative error in case of failure.
2272 *
2273 * u64 bpf_skb_ancestor_cgroup_id(struct sk_buff *skb, int ancestor_level)
2274 *      Description
2275 *              Return id of cgroup v2 that is ancestor of cgroup associated
2276 *              with the *skb* at the *ancestor_level*.  The root cgroup is at
2277 *              *ancestor_level* zero and each step down the hierarchy
2278 *              increments the level. If *ancestor_level* == level of cgroup
2279 *              associated with *skb*, then return value will be same as that
2280 *              of **bpf_skb_cgroup_id**\ ().
2281 *
2282 *              The helper is useful to implement policies based on cgroups
2283 *              that are upper in hierarchy than immediate cgroup associated
2284 *              with *skb*.
2285 *
2286 *              The format of returned id and helper limitations are same as in
2287 *              **bpf_skb_cgroup_id**\ ().
2288 *      Return
2289 *              The id is returned or 0 in case the id could not be retrieved.
2290 *
2291 * struct bpf_sock *bpf_sk_lookup_tcp(void *ctx, struct bpf_sock_tuple *tuple, u32 tuple_size, u64 netns, u64 flags)
2292 *      Description
2293 *              Look for TCP socket matching *tuple*, optionally in a child
2294 *              network namespace *netns*. The return value must be checked,
2295 *              and if non-**NULL**, released via **bpf_sk_release**\ ().
2296 *
2297 *              The *ctx* should point to the context of the program, such as
2298 *              the skb or socket (depending on the hook in use). This is used
2299 *              to determine the base network namespace for the lookup.
2300 *
2301 *              *tuple_size* must be one of:
2302 *
2303 *              **sizeof**\ (*tuple*\ **->ipv4**)
2304 *                      Look for an IPv4 socket.
2305 *              **sizeof**\ (*tuple*\ **->ipv6**)
2306 *                      Look for an IPv6 socket.
2307 *
2308 *              If the *netns* is a negative signed 32-bit integer, then the
2309 *              socket lookup table in the netns associated with the *ctx* will
2310 *              will be used. For the TC hooks, this is the netns of the device
2311 *              in the skb. For socket hooks, this is the netns of the socket.
2312 *              If *netns* is any other signed 32-bit value greater than or
2313 *              equal to zero then it specifies the ID of the netns relative to
2314 *              the netns associated with the *ctx*. *netns* values beyond the
2315 *              range of 32-bit integers are reserved for future use.
2316 *
2317 *              All values for *flags* are reserved for future usage, and must
2318 *              be left at zero.
2319 *
2320 *              This helper is available only if the kernel was compiled with
2321 *              **CONFIG_NET** configuration option.
2322 *      Return
2323 *              Pointer to **struct bpf_sock**, or **NULL** in case of failure.
2324 *              For sockets with reuseport option, the **struct bpf_sock**
2325 *              result is from *reuse*\ **->socks**\ [] using the hash of the
2326 *              tuple.
2327 *
2328 * struct bpf_sock *bpf_sk_lookup_udp(void *ctx, struct bpf_sock_tuple *tuple, u32 tuple_size, u64 netns, u64 flags)
2329 *      Description
2330 *              Look for UDP socket matching *tuple*, optionally in a child
2331 *              network namespace *netns*. The return value must be checked,
2332 *              and if non-**NULL**, released via **bpf_sk_release**\ ().
2333 *
2334 *              The *ctx* should point to the context of the program, such as
2335 *              the skb or socket (depending on the hook in use). This is used
2336 *              to determine the base network namespace for the lookup.
2337 *
2338 *              *tuple_size* must be one of:
2339 *
2340 *              **sizeof**\ (*tuple*\ **->ipv4**)
2341 *                      Look for an IPv4 socket.
2342 *              **sizeof**\ (*tuple*\ **->ipv6**)
2343 *                      Look for an IPv6 socket.
2344 *
2345 *              If the *netns* is a negative signed 32-bit integer, then the
2346 *              socket lookup table in the netns associated with the *ctx* will
2347 *              will be used. For the TC hooks, this is the netns of the device
2348 *              in the skb. For socket hooks, this is the netns of the socket.
2349 *              If *netns* is any other signed 32-bit value greater than or
2350 *              equal to zero then it specifies the ID of the netns relative to
2351 *              the netns associated with the *ctx*. *netns* values beyond the
2352 *              range of 32-bit integers are reserved for future use.
2353 *
2354 *              All values for *flags* are reserved for future usage, and must
2355 *              be left at zero.
2356 *
2357 *              This helper is available only if the kernel was compiled with
2358 *              **CONFIG_NET** configuration option.
2359 *      Return
2360 *              Pointer to **struct bpf_sock**, or **NULL** in case of failure.
2361 *              For sockets with reuseport option, the **struct bpf_sock**
2362 *              result is from *reuse*\ **->socks**\ [] using the hash of the
2363 *              tuple.
2364 *
2365 * int bpf_sk_release(struct bpf_sock *sock)
2366 *      Description
2367 *              Release the reference held by *sock*. *sock* must be a
2368 *              non-**NULL** pointer that was returned from
2369 *              **bpf_sk_lookup_xxx**\ ().
2370 *      Return
2371 *              0 on success, or a negative error in case of failure.
2372 *
2373 * int bpf_map_push_elem(struct bpf_map *map, const void *value, u64 flags)
2374 *      Description
2375 *              Push an element *value* in *map*. *flags* is one of:
2376 *
2377 *              **BPF_EXIST**
2378 *                      If the queue/stack is full, the oldest element is
2379 *                      removed to make room for this.
2380 *      Return
2381 *              0 on success, or a negative error in case of failure.
2382 *
2383 * int bpf_map_pop_elem(struct bpf_map *map, void *value)
2384 *      Description
2385 *              Pop an element from *map*.
2386 *      Return
2387 *              0 on success, or a negative error in case of failure.
2388 *
2389 * int bpf_map_peek_elem(struct bpf_map *map, void *value)
2390 *      Description
2391 *              Get an element from *map* without removing it.
2392 *      Return
2393 *              0 on success, or a negative error in case of failure.
2394 *
2395 * int bpf_msg_push_data(struct sk_buff *skb, u32 start, u32 len, u64 flags)
2396 *      Description
2397 *              For socket policies, insert *len* bytes into *msg* at offset
2398 *              *start*.
2399 *
2400 *              If a program of type **BPF_PROG_TYPE_SK_MSG** is run on a
2401 *              *msg* it may want to insert metadata or options into the *msg*.
2402 *              This can later be read and used by any of the lower layer BPF
2403 *              hooks.
2404 *
2405 *              This helper may fail if under memory pressure (a malloc
2406 *              fails) in these cases BPF programs will get an appropriate
2407 *              error and BPF programs will need to handle them.
2408 *      Return
2409 *              0 on success, or a negative error in case of failure.
2410 *
2411 * int bpf_msg_pop_data(struct sk_msg_buff *msg, u32 start, u32 pop, u64 flags)
2412 *      Description
2413 *              Will remove *pop* bytes from a *msg* starting at byte *start*.
2414 *              This may result in **ENOMEM** errors under certain situations if
2415 *              an allocation and copy are required due to a full ring buffer.
2416 *              However, the helper will try to avoid doing the allocation
2417 *              if possible. Other errors can occur if input parameters are
2418 *              invalid either due to *start* byte not being valid part of *msg*
2419 *              payload and/or *pop* value being to large.
2420 *      Return
2421 *              0 on success, or a negative error in case of failure.
2422 *
2423 * int bpf_rc_pointer_rel(void *ctx, s32 rel_x, s32 rel_y)
2424 *      Description
2425 *              This helper is used in programs implementing IR decoding, to
2426 *              report a successfully decoded pointer movement.
2427 *
2428 *              The *ctx* should point to the lirc sample as passed into
2429 *              the program.
2430 *
2431 *              This helper is only available is the kernel was compiled with
2432 *              the **CONFIG_BPF_LIRC_MODE2** configuration option set to
2433 *              "**y**".
2434 *      Return
2435 *              0
2436 *
2437 * int bpf_spin_lock(struct bpf_spin_lock *lock)
2438 *      Description
2439 *              Acquire a spinlock represented by the pointer *lock*, which is
2440 *              stored as part of a value of a map. Taking the lock allows to
2441 *              safely update the rest of the fields in that value. The
2442 *              spinlock can (and must) later be released with a call to
2443 *              **bpf_spin_unlock**\ (\ *lock*\ ).
2444 *
2445 *              Spinlocks in BPF programs come with a number of restrictions
2446 *              and constraints:
2447 *
2448 *              * **bpf_spin_lock** objects are only allowed inside maps of
2449 *                types **BPF_MAP_TYPE_HASH** and **BPF_MAP_TYPE_ARRAY** (this
2450 *                list could be extended in the future).
2451 *              * BTF description of the map is mandatory.
2452 *              * The BPF program can take ONE lock at a time, since taking two
2453 *                or more could cause dead locks.
2454 *              * Only one **struct bpf_spin_lock** is allowed per map element.
2455 *              * When the lock is taken, calls (either BPF to BPF or helpers)
2456 *                are not allowed.
2457 *              * The **BPF_LD_ABS** and **BPF_LD_IND** instructions are not
2458 *                allowed inside a spinlock-ed region.
2459 *              * The BPF program MUST call **bpf_spin_unlock**\ () to release
2460 *                the lock, on all execution paths, before it returns.
2461 *              * The BPF program can access **struct bpf_spin_lock** only via
2462 *                the **bpf_spin_lock**\ () and **bpf_spin_unlock**\ ()
2463 *                helpers. Loading or storing data into the **struct
2464 *                bpf_spin_lock** *lock*\ **;** field of a map is not allowed.
2465 *              * To use the **bpf_spin_lock**\ () helper, the BTF description
2466 *                of the map value must be a struct and have **struct
2467 *                bpf_spin_lock** *anyname*\ **;** field at the top level.
2468 *                Nested lock inside another struct is not allowed.
2469 *              * The **struct bpf_spin_lock** *lock* field in a map value must
2470 *                be aligned on a multiple of 4 bytes in that value.
2471 *              * Syscall with command **BPF_MAP_LOOKUP_ELEM** does not copy
2472 *                the **bpf_spin_lock** field to user space.
2473 *              * Syscall with command **BPF_MAP_UPDATE_ELEM**, or update from
2474 *                a BPF program, do not update the **bpf_spin_lock** field.
2475 *              * **bpf_spin_lock** cannot be on the stack or inside a
2476 *                networking packet (it can only be inside of a map values).
2477 *              * **bpf_spin_lock** is available to root only.
2478 *              * Tracing programs and socket filter programs cannot use
2479 *                **bpf_spin_lock**\ () due to insufficient preemption checks
2480 *                (but this may change in the future).
2481 *              * **bpf_spin_lock** is not allowed in inner maps of map-in-map.
2482 *      Return
2483 *              0
2484 *
2485 * int bpf_spin_unlock(struct bpf_spin_lock *lock)
2486 *      Description
2487 *              Release the *lock* previously locked by a call to
2488 *              **bpf_spin_lock**\ (\ *lock*\ ).
2489 *      Return
2490 *              0
2491 *
2492 * struct bpf_sock *bpf_sk_fullsock(struct bpf_sock *sk)
2493 *      Description
2494 *              This helper gets a **struct bpf_sock** pointer such
2495 *              that all the fields in this **bpf_sock** can be accessed.
2496 *      Return
2497 *              A **struct bpf_sock** pointer on success, or **NULL** in
2498 *              case of failure.
2499 *
2500 * struct bpf_tcp_sock *bpf_tcp_sock(struct bpf_sock *sk)
2501 *      Description
2502 *              This helper gets a **struct bpf_tcp_sock** pointer from a
2503 *              **struct bpf_sock** pointer.
2504 *      Return
2505 *              A **struct bpf_tcp_sock** pointer on success, or **NULL** in
2506 *              case of failure.
2507 *
2508 * int bpf_skb_ecn_set_ce(struct sk_buf *skb)
2509 *      Description
2510 *              Set ECN (Explicit Congestion Notification) field of IP header
2511 *              to **CE** (Congestion Encountered) if current value is **ECT**
2512 *              (ECN Capable Transport). Otherwise, do nothing. Works with IPv6
2513 *              and IPv4.
2514 *      Return
2515 *              1 if the **CE** flag is set (either by the current helper call
2516 *              or because it was already present), 0 if it is not set.
2517 *
2518 * struct bpf_sock *bpf_get_listener_sock(struct bpf_sock *sk)
2519 *      Description
2520 *              Return a **struct bpf_sock** pointer in **TCP_LISTEN** state.
2521 *              **bpf_sk_release**\ () is unnecessary and not allowed.
2522 *      Return
2523 *              A **struct bpf_sock** pointer on success, or **NULL** in
2524 *              case of failure.
2525 *
2526 * struct bpf_sock *bpf_skc_lookup_tcp(void *ctx, struct bpf_sock_tuple *tuple, u32 tuple_size, u64 netns, u64 flags)
2527 *      Description
2528 *              Look for TCP socket matching *tuple*, optionally in a child
2529 *              network namespace *netns*. The return value must be checked,
2530 *              and if non-**NULL**, released via **bpf_sk_release**\ ().
2531 *
2532 *              This function is identical to **bpf_sk_lookup_tcp**\ (), except
2533 *              that it also returns timewait or request sockets. Use
2534 *              **bpf_sk_fullsock**\ () or **bpf_tcp_sock**\ () to access the
2535 *              full structure.
2536 *
2537 *              This helper is available only if the kernel was compiled with
2538 *              **CONFIG_NET** configuration option.
2539 *      Return
2540 *              Pointer to **struct bpf_sock**, or **NULL** in case of failure.
2541 *              For sockets with reuseport option, the **struct bpf_sock**
2542 *              result is from *reuse*\ **->socks**\ [] using the hash of the
2543 *              tuple.
2544 *
2545 * int bpf_tcp_check_syncookie(struct bpf_sock *sk, void *iph, u32 iph_len, struct tcphdr *th, u32 th_len)
2546 *      Description
2547 *              Check whether *iph* and *th* contain a valid SYN cookie ACK for
2548 *              the listening socket in *sk*.
2549 *
2550 *              *iph* points to the start of the IPv4 or IPv6 header, while
2551 *              *iph_len* contains **sizeof**\ (**struct iphdr**) or
2552 *              **sizeof**\ (**struct ip6hdr**).
2553 *
2554 *              *th* points to the start of the TCP header, while *th_len*
2555 *              contains **sizeof**\ (**struct tcphdr**).
2556 *
2557 *      Return
2558 *              0 if *iph* and *th* are a valid SYN cookie ACK, or a negative
2559 *              error otherwise.
2560 *
2561 * int bpf_sysctl_get_name(struct bpf_sysctl *ctx, char *buf, size_t buf_len, u64 flags)
2562 *      Description
2563 *              Get name of sysctl in /proc/sys/ and copy it into provided by
2564 *              program buffer *buf* of size *buf_len*.
2565 *
2566 *              The buffer is always NUL terminated, unless it's zero-sized.
2567 *
2568 *              If *flags* is zero, full name (e.g. "net/ipv4/tcp_mem") is
2569 *              copied. Use **BPF_F_SYSCTL_BASE_NAME** flag to copy base name
2570 *              only (e.g. "tcp_mem").
2571 *      Return
2572 *              Number of character copied (not including the trailing NUL).
2573 *
2574 *              **-E2BIG** if the buffer wasn't big enough (*buf* will contain
2575 *              truncated name in this case).
2576 *
2577 * int bpf_sysctl_get_current_value(struct bpf_sysctl *ctx, char *buf, size_t buf_len)
2578 *      Description
2579 *              Get current value of sysctl as it is presented in /proc/sys
2580 *              (incl. newline, etc), and copy it as a string into provided
2581 *              by program buffer *buf* of size *buf_len*.
2582 *
2583 *              The whole value is copied, no matter what file position user
2584 *              space issued e.g. sys_read at.
2585 *
2586 *              The buffer is always NUL terminated, unless it's zero-sized.
2587 *      Return
2588 *              Number of character copied (not including the trailing NUL).
2589 *
2590 *              **-E2BIG** if the buffer wasn't big enough (*buf* will contain
2591 *              truncated name in this case).
2592 *
2593 *              **-EINVAL** if current value was unavailable, e.g. because
2594 *              sysctl is uninitialized and read returns -EIO for it.
2595 *
2596 * int bpf_sysctl_get_new_value(struct bpf_sysctl *ctx, char *buf, size_t buf_len)
2597 *      Description
2598 *              Get new value being written by user space to sysctl (before
2599 *              the actual write happens) and copy it as a string into
2600 *              provided by program buffer *buf* of size *buf_len*.
2601 *
2602 *              User space may write new value at file position > 0.
2603 *
2604 *              The buffer is always NUL terminated, unless it's zero-sized.
2605 *      Return
2606 *              Number of character copied (not including the trailing NUL).
2607 *
2608 *              **-E2BIG** if the buffer wasn't big enough (*buf* will contain
2609 *              truncated name in this case).
2610 *
2611 *              **-EINVAL** if sysctl is being read.
2612 *
2613 * int bpf_sysctl_set_new_value(struct bpf_sysctl *ctx, const char *buf, size_t buf_len)
2614 *      Description
2615 *              Override new value being written by user space to sysctl with
2616 *              value provided by program in buffer *buf* of size *buf_len*.
2617 *
2618 *              *buf* should contain a string in same form as provided by user
2619 *              space on sysctl write.
2620 *
2621 *              User space may write new value at file position > 0. To override
2622 *              the whole sysctl value file position should be set to zero.
2623 *      Return
2624 *              0 on success.
2625 *
2626 *              **-E2BIG** if the *buf_len* is too big.
2627 *
2628 *              **-EINVAL** if sysctl is being read.
2629 *
2630 * int bpf_strtol(const char *buf, size_t buf_len, u64 flags, long *res)
2631 *      Description
2632 *              Convert the initial part of the string from buffer *buf* of
2633 *              size *buf_len* to a long integer according to the given base
2634 *              and save the result in *res*.
2635 *
2636 *              The string may begin with an arbitrary amount of white space
2637 *              (as determined by **isspace**\ (3)) followed by a single
2638 *              optional '**-**' sign.
2639 *
2640 *              Five least significant bits of *flags* encode base, other bits
2641 *              are currently unused.
2642 *
2643 *              Base must be either 8, 10, 16 or 0 to detect it automatically
2644 *              similar to user space **strtol**\ (3).
2645 *      Return
2646 *              Number of characters consumed on success. Must be positive but
2647 *              no more than *buf_len*.
2648 *
2649 *              **-EINVAL** if no valid digits were found or unsupported base
2650 *              was provided.
2651 *
2652 *              **-ERANGE** if resulting value was out of range.
2653 *
2654 * int bpf_strtoul(const char *buf, size_t buf_len, u64 flags, unsigned long *res)
2655 *      Description
2656 *              Convert the initial part of the string from buffer *buf* of
2657 *              size *buf_len* to an unsigned long integer according to the
2658 *              given base and save the result in *res*.
2659 *
2660 *              The string may begin with an arbitrary amount of white space
2661 *              (as determined by **isspace**\ (3)).
2662 *
2663 *              Five least significant bits of *flags* encode base, other bits
2664 *              are currently unused.
2665 *
2666 *              Base must be either 8, 10, 16 or 0 to detect it automatically
2667 *              similar to user space **strtoul**\ (3).
2668 *      Return
2669 *              Number of characters consumed on success. Must be positive but
2670 *              no more than *buf_len*.
2671 *
2672 *              **-EINVAL** if no valid digits were found or unsupported base
2673 *              was provided.
2674 *
2675 *              **-ERANGE** if resulting value was out of range.
2676 *
2677 * void *bpf_sk_storage_get(struct bpf_map *map, struct bpf_sock *sk, void *value, u64 flags)
2678 *      Description
2679 *              Get a bpf-local-storage from a *sk*.
2680 *
2681 *              Logically, it could be thought of getting the value from
2682 *              a *map* with *sk* as the **key**.  From this
2683 *              perspective,  the usage is not much different from
2684 *              **bpf_map_lookup_elem**\ (*map*, **&**\ *sk*) except this
2685 *              helper enforces the key must be a full socket and the map must
2686 *              be a **BPF_MAP_TYPE_SK_STORAGE** also.
2687 *
2688 *              Underneath, the value is stored locally at *sk* instead of
2689 *              the *map*.  The *map* is used as the bpf-local-storage
2690 *              "type". The bpf-local-storage "type" (i.e. the *map*) is
2691 *              searched against all bpf-local-storages residing at *sk*.
2692 *
2693 *              An optional *flags* (**BPF_SK_STORAGE_GET_F_CREATE**) can be
2694 *              used such that a new bpf-local-storage will be
2695 *              created if one does not exist.  *value* can be used
2696 *              together with **BPF_SK_STORAGE_GET_F_CREATE** to specify
2697 *              the initial value of a bpf-local-storage.  If *value* is
2698 *              **NULL**, the new bpf-local-storage will be zero initialized.
2699 *      Return
2700 *              A bpf-local-storage pointer is returned on success.
2701 *
2702 *              **NULL** if not found or there was an error in adding
2703 *              a new bpf-local-storage.
2704 *
2705 * int bpf_sk_storage_delete(struct bpf_map *map, struct bpf_sock *sk)
2706 *      Description
2707 *              Delete a bpf-local-storage from a *sk*.
2708 *      Return
2709 *              0 on success.
2710 *
2711 *              **-ENOENT** if the bpf-local-storage cannot be found.
2712 *
2713 * int bpf_send_signal(u32 sig)
2714 *      Description
2715 *              Send signal *sig* to the current task.
2716 *      Return
2717 *              0 on success or successfully queued.
2718 *
2719 *              **-EBUSY** if work queue under nmi is full.
2720 *
2721 *              **-EINVAL** if *sig* is invalid.
2722 *
2723 *              **-EPERM** if no permission to send the *sig*.
2724 *
2725 *              **-EAGAIN** if bpf program can try again.
2726 *
2727 * s64 bpf_tcp_gen_syncookie(struct bpf_sock *sk, void *iph, u32 iph_len, struct tcphdr *th, u32 th_len)
2728 *      Description
2729 *              Try to issue a SYN cookie for the packet with corresponding
2730 *              IP/TCP headers, *iph* and *th*, on the listening socket in *sk*.
2731 *
2732 *              *iph* points to the start of the IPv4 or IPv6 header, while
2733 *              *iph_len* contains **sizeof**\ (**struct iphdr**) or
2734 *              **sizeof**\ (**struct ip6hdr**).
2735 *
2736 *              *th* points to the start of the TCP header, while *th_len*
2737 *              contains the length of the TCP header.
2738 *
2739 *      Return
2740 *              On success, lower 32 bits hold the generated SYN cookie in
2741 *              followed by 16 bits which hold the MSS value for that cookie,
2742 *              and the top 16 bits are unused.
2743 *
2744 *              On failure, the returned value is one of the following:
2745 *
2746 *              **-EINVAL** SYN cookie cannot be issued due to error
2747 *
2748 *              **-ENOENT** SYN cookie should not be issued (no SYN flood)
2749 *
2750 *              **-EOPNOTSUPP** kernel configuration does not enable SYN cookies
2751 *
2752 *              **-EPROTONOSUPPORT** IP packet version is not 4 or 6
2753 */
2754#define __BPF_FUNC_MAPPER(FN)           \
2755        FN(unspec),                     \
2756        FN(map_lookup_elem),            \
2757        FN(map_update_elem),            \
2758        FN(map_delete_elem),            \
2759        FN(probe_read),                 \
2760        FN(ktime_get_ns),               \
2761        FN(trace_printk),               \
2762        FN(get_prandom_u32),            \
2763        FN(get_smp_processor_id),       \
2764        FN(skb_store_bytes),            \
2765        FN(l3_csum_replace),            \
2766        FN(l4_csum_replace),            \
2767        FN(tail_call),                  \
2768        FN(clone_redirect),             \
2769        FN(get_current_pid_tgid),       \
2770        FN(get_current_uid_gid),        \
2771        FN(get_current_comm),           \
2772        FN(get_cgroup_classid),         \
2773        FN(skb_vlan_push),              \
2774        FN(skb_vlan_pop),               \
2775        FN(skb_get_tunnel_key),         \
2776        FN(skb_set_tunnel_key),         \
2777        FN(perf_event_read),            \
2778        FN(redirect),                   \
2779        FN(get_route_realm),            \
2780        FN(perf_event_output),          \
2781        FN(skb_load_bytes),             \
2782        FN(get_stackid),                \
2783        FN(csum_diff),                  \
2784        FN(skb_get_tunnel_opt),         \
2785        FN(skb_set_tunnel_opt),         \
2786        FN(skb_change_proto),           \
2787        FN(skb_change_type),            \
2788        FN(skb_under_cgroup),           \
2789        FN(get_hash_recalc),            \
2790        FN(get_current_task),           \
2791        FN(probe_write_user),           \
2792        FN(current_task_under_cgroup),  \
2793        FN(skb_change_tail),            \
2794        FN(skb_pull_data),              \
2795        FN(csum_update),                \
2796        FN(set_hash_invalid),           \
2797        FN(get_numa_node_id),           \
2798        FN(skb_change_head),            \
2799        FN(xdp_adjust_head),            \
2800        FN(probe_read_str),             \
2801        FN(get_socket_cookie),          \
2802        FN(get_socket_uid),             \
2803        FN(set_hash),                   \
2804        FN(setsockopt),                 \
2805        FN(skb_adjust_room),            \
2806        FN(redirect_map),               \
2807        FN(sk_redirect_map),            \
2808        FN(sock_map_update),            \
2809        FN(xdp_adjust_meta),            \
2810        FN(perf_event_read_value),      \
2811        FN(perf_prog_read_value),       \
2812        FN(getsockopt),                 \
2813        FN(override_return),            \
2814        FN(sock_ops_cb_flags_set),      \
2815        FN(msg_redirect_map),           \
2816        FN(msg_apply_bytes),            \
2817        FN(msg_cork_bytes),             \
2818        FN(msg_pull_data),              \
2819        FN(bind),                       \
2820        FN(xdp_adjust_tail),            \
2821        FN(skb_get_xfrm_state),         \
2822        FN(get_stack),                  \
2823        FN(skb_load_bytes_relative),    \
2824        FN(fib_lookup),                 \
2825        FN(sock_hash_update),           \
2826        FN(msg_redirect_hash),          \
2827        FN(sk_redirect_hash),           \
2828        FN(lwt_push_encap),             \
2829        FN(lwt_seg6_store_bytes),       \
2830        FN(lwt_seg6_adjust_srh),        \
2831        FN(lwt_seg6_action),            \
2832        FN(rc_repeat),                  \
2833        FN(rc_keydown),                 \
2834        FN(skb_cgroup_id),              \
2835        FN(get_current_cgroup_id),      \
2836        FN(get_local_storage),          \
2837        FN(sk_select_reuseport),        \
2838        FN(skb_ancestor_cgroup_id),     \
2839        FN(sk_lookup_tcp),              \
2840        FN(sk_lookup_udp),              \
2841        FN(sk_release),                 \
2842        FN(map_push_elem),              \
2843        FN(map_pop_elem),               \
2844        FN(map_peek_elem),              \
2845        FN(msg_push_data),              \
2846        FN(msg_pop_data),               \
2847        FN(rc_pointer_rel),             \
2848        FN(spin_lock),                  \
2849        FN(spin_unlock),                \
2850        FN(sk_fullsock),                \
2851        FN(tcp_sock),                   \
2852        FN(skb_ecn_set_ce),             \
2853        FN(get_listener_sock),          \
2854        FN(skc_lookup_tcp),             \
2855        FN(tcp_check_syncookie),        \
2856        FN(sysctl_get_name),            \
2857        FN(sysctl_get_current_value),   \
2858        FN(sysctl_get_new_value),       \
2859        FN(sysctl_set_new_value),       \
2860        FN(strtol),                     \
2861        FN(strtoul),                    \
2862        FN(sk_storage_get),             \
2863        FN(sk_storage_delete),          \
2864        FN(send_signal),                \
2865        FN(tcp_gen_syncookie),
2866
2867/* integer value in 'imm' field of BPF_CALL instruction selects which helper
2868 * function eBPF program intends to call
2869 */
2870#define __BPF_ENUM_FN(x) BPF_FUNC_ ## x
2871enum bpf_func_id {
2872        __BPF_FUNC_MAPPER(__BPF_ENUM_FN)
2873        __BPF_FUNC_MAX_ID,
2874};
2875#undef __BPF_ENUM_FN
2876
2877/* All flags used by eBPF helper functions, placed here. */
2878
2879/* BPF_FUNC_skb_store_bytes flags. */
2880#define BPF_F_RECOMPUTE_CSUM            (1ULL << 0)
2881#define BPF_F_INVALIDATE_HASH           (1ULL << 1)
2882
2883/* BPF_FUNC_l3_csum_replace and BPF_FUNC_l4_csum_replace flags.
2884 * First 4 bits are for passing the header field size.
2885 */
2886#define BPF_F_HDR_FIELD_MASK            0xfULL
2887
2888/* BPF_FUNC_l4_csum_replace flags. */
2889#define BPF_F_PSEUDO_HDR                (1ULL << 4)
2890#define BPF_F_MARK_MANGLED_0            (1ULL << 5)
2891#define BPF_F_MARK_ENFORCE              (1ULL << 6)
2892
2893/* BPF_FUNC_clone_redirect and BPF_FUNC_redirect flags. */
2894#define BPF_F_INGRESS                   (1ULL << 0)
2895
2896/* BPF_FUNC_skb_set_tunnel_key and BPF_FUNC_skb_get_tunnel_key flags. */
2897#define BPF_F_TUNINFO_IPV6              (1ULL << 0)
2898
2899/* flags for both BPF_FUNC_get_stackid and BPF_FUNC_get_stack. */
2900#define BPF_F_SKIP_FIELD_MASK           0xffULL
2901#define BPF_F_USER_STACK                (1ULL << 8)
2902/* flags used by BPF_FUNC_get_stackid only. */
2903#define BPF_F_FAST_STACK_CMP            (1ULL << 9)
2904#define BPF_F_REUSE_STACKID             (1ULL << 10)
2905/* flags used by BPF_FUNC_get_stack only. */
2906#define BPF_F_USER_BUILD_ID             (1ULL << 11)
2907
2908/* BPF_FUNC_skb_set_tunnel_key flags. */
2909#define BPF_F_ZERO_CSUM_TX              (1ULL << 1)
2910#define BPF_F_DONT_FRAGMENT             (1ULL << 2)
2911#define BPF_F_SEQ_NUMBER                (1ULL << 3)
2912
2913/* BPF_FUNC_perf_event_output, BPF_FUNC_perf_event_read and
2914 * BPF_FUNC_perf_event_read_value flags.
2915 */
2916#define BPF_F_INDEX_MASK                0xffffffffULL
2917#define BPF_F_CURRENT_CPU               BPF_F_INDEX_MASK
2918/* BPF_FUNC_perf_event_output for sk_buff input context. */
2919#define BPF_F_CTXLEN_MASK               (0xfffffULL << 32)
2920
2921/* Current network namespace */
2922#define BPF_F_CURRENT_NETNS             (-1L)
2923
2924/* BPF_FUNC_skb_adjust_room flags. */
2925#define BPF_F_ADJ_ROOM_FIXED_GSO        (1ULL << 0)
2926
2927#define BPF_ADJ_ROOM_ENCAP_L2_MASK      0xff
2928#define BPF_ADJ_ROOM_ENCAP_L2_SHIFT     56
2929
2930#define BPF_F_ADJ_ROOM_ENCAP_L3_IPV4    (1ULL << 1)
2931#define BPF_F_ADJ_ROOM_ENCAP_L3_IPV6    (1ULL << 2)
2932#define BPF_F_ADJ_ROOM_ENCAP_L4_GRE     (1ULL << 3)
2933#define BPF_F_ADJ_ROOM_ENCAP_L4_UDP     (1ULL << 4)
2934#define BPF_F_ADJ_ROOM_ENCAP_L2(len)    (((__u64)len & \
2935                                          BPF_ADJ_ROOM_ENCAP_L2_MASK) \
2936                                         << BPF_ADJ_ROOM_ENCAP_L2_SHIFT)
2937
2938/* BPF_FUNC_sysctl_get_name flags. */
2939#define BPF_F_SYSCTL_BASE_NAME          (1ULL << 0)
2940
2941/* BPF_FUNC_sk_storage_get flags */
2942#define BPF_SK_STORAGE_GET_F_CREATE     (1ULL << 0)
2943
2944/* Mode for BPF_FUNC_skb_adjust_room helper. */
2945enum bpf_adj_room_mode {
2946        BPF_ADJ_ROOM_NET,
2947        BPF_ADJ_ROOM_MAC,
2948};
2949
2950/* Mode for BPF_FUNC_skb_load_bytes_relative helper. */
2951enum bpf_hdr_start_off {
2952        BPF_HDR_START_MAC,
2953        BPF_HDR_START_NET,
2954};
2955
2956/* Encapsulation type for BPF_FUNC_lwt_push_encap helper. */
2957enum bpf_lwt_encap_mode {
2958        BPF_LWT_ENCAP_SEG6,
2959        BPF_LWT_ENCAP_SEG6_INLINE,
2960        BPF_LWT_ENCAP_IP,
2961};
2962
2963#define __bpf_md_ptr(type, name)        \
2964union {                                 \
2965        type name;                      \
2966        __u64 :64;                      \
2967} __attribute__((aligned(8)))
2968
2969/* user accessible mirror of in-kernel sk_buff.
2970 * new fields can only be added to the end of this structure
2971 */
2972struct __sk_buff {
2973        __u32 len;
2974        __u32 pkt_type;
2975        __u32 mark;
2976        __u32 queue_mapping;
2977        __u32 protocol;
2978        __u32 vlan_present;
2979        __u32 vlan_tci;
2980        __u32 vlan_proto;
2981        __u32 priority;
2982        __u32 ingress_ifindex;
2983        __u32 ifindex;
2984        __u32 tc_index;
2985        __u32 cb[5];
2986        __u32 hash;
2987        __u32 tc_classid;
2988        __u32 data;
2989        __u32 data_end;
2990        __u32 napi_id;
2991
2992        /* Accessed by BPF_PROG_TYPE_sk_skb types from here to ... */
2993        __u32 family;
2994        __u32 remote_ip4;       /* Stored in network byte order */
2995        __u32 local_ip4;        /* Stored in network byte order */
2996        __u32 remote_ip6[4];    /* Stored in network byte order */
2997        __u32 local_ip6[4];     /* Stored in network byte order */
2998        __u32 remote_port;      /* Stored in network byte order */
2999        __u32 local_port;       /* stored in host byte order */
3000        /* ... here. */
3001
3002        __u32 data_meta;
3003        __bpf_md_ptr(struct bpf_flow_keys *, flow_keys);
3004        __u64 tstamp;
3005        __u32 wire_len;
3006        __u32 gso_segs;
3007        __bpf_md_ptr(struct bpf_sock *, sk);
3008};
3009
3010struct bpf_tunnel_key {
3011        __u32 tunnel_id;
3012        union {
3013                __u32 remote_ipv4;
3014                __u32 remote_ipv6[4];
3015        };
3016        __u8 tunnel_tos;
3017        __u8 tunnel_ttl;
3018        __u16 tunnel_ext;       /* Padding, future use. */
3019        __u32 tunnel_label;
3020};
3021
3022/* user accessible mirror of in-kernel xfrm_state.
3023 * new fields can only be added to the end of this structure
3024 */
3025struct bpf_xfrm_state {
3026        __u32 reqid;
3027        __u32 spi;      /* Stored in network byte order */
3028        __u16 family;
3029        __u16 ext;      /* Padding, future use. */
3030        union {
3031                __u32 remote_ipv4;      /* Stored in network byte order */
3032                __u32 remote_ipv6[4];   /* Stored in network byte order */
3033        };
3034};
3035
3036/* Generic BPF return codes which all BPF program types may support.
3037 * The values are binary compatible with their TC_ACT_* counter-part to
3038 * provide backwards compatibility with existing SCHED_CLS and SCHED_ACT
3039 * programs.
3040 *
3041 * XDP is handled seprately, see XDP_*.
3042 */
3043enum bpf_ret_code {
3044        BPF_OK = 0,
3045        /* 1 reserved */
3046        BPF_DROP = 2,
3047        /* 3-6 reserved */
3048        BPF_REDIRECT = 7,
3049        /* >127 are reserved for prog type specific return codes.
3050         *
3051         * BPF_LWT_REROUTE: used by BPF_PROG_TYPE_LWT_IN and
3052         *    BPF_PROG_TYPE_LWT_XMIT to indicate that skb had been
3053         *    changed and should be routed based on its new L3 header.
3054         *    (This is an L3 redirect, as opposed to L2 redirect
3055         *    represented by BPF_REDIRECT above).
3056         */
3057        BPF_LWT_REROUTE = 128,
3058};
3059
3060struct bpf_sock {
3061        __u32 bound_dev_if;
3062        __u32 family;
3063        __u32 type;
3064        __u32 protocol;
3065        __u32 mark;
3066        __u32 priority;
3067        /* IP address also allows 1 and 2 bytes access */
3068        __u32 src_ip4;
3069        __u32 src_ip6[4];
3070        __u32 src_port;         /* host byte order */
3071        __u32 dst_port;         /* network byte order */
3072        __u32 dst_ip4;
3073        __u32 dst_ip6[4];
3074        __u32 state;
3075};
3076
3077struct bpf_tcp_sock {
3078        __u32 snd_cwnd;         /* Sending congestion window            */
3079        __u32 srtt_us;          /* smoothed round trip time << 3 in usecs */
3080        __u32 rtt_min;
3081        __u32 snd_ssthresh;     /* Slow start size threshold            */
3082        __u32 rcv_nxt;          /* What we want to receive next         */
3083        __u32 snd_nxt;          /* Next sequence we send                */
3084        __u32 snd_una;          /* First byte we want an ack for        */
3085        __u32 mss_cache;        /* Cached effective mss, not including SACKS */
3086        __u32 ecn_flags;        /* ECN status bits.                     */
3087        __u32 rate_delivered;   /* saved rate sample: packets delivered */
3088        __u32 rate_interval_us; /* saved rate sample: time elapsed */
3089        __u32 packets_out;      /* Packets which are "in flight"        */
3090        __u32 retrans_out;      /* Retransmitted packets out            */
3091        __u32 total_retrans;    /* Total retransmits for entire connection */
3092        __u32 segs_in;          /* RFC4898 tcpEStatsPerfSegsIn
3093                                 * total number of segments in.
3094                                 */
3095        __u32 data_segs_in;     /* RFC4898 tcpEStatsPerfDataSegsIn
3096                                 * total number of data segments in.
3097                                 */
3098        __u32 segs_out;         /* RFC4898 tcpEStatsPerfSegsOut
3099                                 * The total number of segments sent.
3100                                 */
3101        __u32 data_segs_out;    /* RFC4898 tcpEStatsPerfDataSegsOut
3102                                 * total number of data segments sent.
3103                                 */
3104        __u32 lost_out;         /* Lost packets                 */
3105        __u32 sacked_out;       /* SACK'd packets                       */
3106        __u64 bytes_received;   /* RFC4898 tcpEStatsAppHCThruOctetsReceived
3107                                 * sum(delta(rcv_nxt)), or how many bytes
3108                                 * were acked.
3109                                 */
3110        __u64 bytes_acked;      /* RFC4898 tcpEStatsAppHCThruOctetsAcked
3111                                 * sum(delta(snd_una)), or how many bytes
3112                                 * were acked.
3113                                 */
3114        __u32 dsack_dups;       /* RFC4898 tcpEStatsStackDSACKDups
3115                                 * total number of DSACK blocks received
3116                                 */
3117        __u32 delivered;        /* Total data packets delivered incl. rexmits */
3118        __u32 delivered_ce;     /* Like the above but only ECE marked packets */
3119        __u32 icsk_retransmits; /* Number of unrecovered [RTO] timeouts */
3120};
3121
3122struct bpf_sock_tuple {
3123        union {
3124                struct {
3125                        __be32 saddr;
3126                        __be32 daddr;
3127                        __be16 sport;
3128                        __be16 dport;
3129                } ipv4;
3130                struct {
3131                        __be32 saddr[4];
3132                        __be32 daddr[4];
3133                        __be16 sport;
3134                        __be16 dport;
3135                } ipv6;
3136        };
3137};
3138
3139struct bpf_xdp_sock {
3140        __u32 queue_id;
3141};
3142
3143#define XDP_PACKET_HEADROOM 256
3144
3145/* User return codes for XDP prog type.
3146 * A valid XDP program must return one of these defined values. All other
3147 * return codes are reserved for future use. Unknown return codes will
3148 * result in packet drops and a warning via bpf_warn_invalid_xdp_action().
3149 */
3150enum xdp_action {
3151        XDP_ABORTED = 0,
3152        XDP_DROP,
3153        XDP_PASS,
3154        XDP_TX,
3155        XDP_REDIRECT,
3156};
3157
3158/* user accessible metadata for XDP packet hook
3159 * new fields must be added to the end of this structure
3160 */
3161struct xdp_md {
3162        __u32 data;
3163        __u32 data_end;
3164        __u32 data_meta;
3165        /* Below access go through struct xdp_rxq_info */
3166        __u32 ingress_ifindex; /* rxq->dev->ifindex */
3167        __u32 rx_queue_index;  /* rxq->queue_index  */
3168};
3169
3170enum sk_action {
3171        SK_DROP = 0,
3172        SK_PASS,
3173};
3174
3175/* user accessible metadata for SK_MSG packet hook, new fields must
3176 * be added to the end of this structure
3177 */
3178struct sk_msg_md {
3179        __bpf_md_ptr(void *, data);
3180        __bpf_md_ptr(void *, data_end);
3181
3182        __u32 family;
3183        __u32 remote_ip4;       /* Stored in network byte order */
3184        __u32 local_ip4;        /* Stored in network byte order */
3185        __u32 remote_ip6[4];    /* Stored in network byte order */
3186        __u32 local_ip6[4];     /* Stored in network byte order */
3187        __u32 remote_port;      /* Stored in network byte order */
3188        __u32 local_port;       /* stored in host byte order */
3189        __u32 size;             /* Total size of sk_msg */
3190};
3191
3192struct sk_reuseport_md {
3193        /*
3194         * Start of directly accessible data. It begins from
3195         * the tcp/udp header.
3196         */
3197        __bpf_md_ptr(void *, data);
3198        /* End of directly accessible data */
3199        __bpf_md_ptr(void *, data_end);
3200        /*
3201         * Total length of packet (starting from the tcp/udp header).
3202         * Note that the directly accessible bytes (data_end - data)
3203         * could be less than this "len".  Those bytes could be
3204         * indirectly read by a helper "bpf_skb_load_bytes()".
3205         */
3206        __u32 len;
3207        /*
3208         * Eth protocol in the mac header (network byte order). e.g.
3209         * ETH_P_IP(0x0800) and ETH_P_IPV6(0x86DD)
3210         */
3211        __u32 eth_protocol;
3212        __u32 ip_protocol;      /* IP protocol. e.g. IPPROTO_TCP, IPPROTO_UDP */
3213        __u32 bind_inany;       /* Is sock bound to an INANY address? */
3214        __u32 hash;             /* A hash of the packet 4 tuples */
3215};
3216
3217#define BPF_TAG_SIZE    8
3218
3219struct bpf_prog_info {
3220        __u32 type;
3221        __u32 id;
3222        __u8  tag[BPF_TAG_SIZE];
3223        __u32 jited_prog_len;
3224        __u32 xlated_prog_len;
3225        __aligned_u64 jited_prog_insns;
3226        __aligned_u64 xlated_prog_insns;
3227        __u64 load_time;        /* ns since boottime */
3228        __u32 created_by_uid;
3229        __u32 nr_map_ids;
3230        __aligned_u64 map_ids;
3231        char name[BPF_OBJ_NAME_LEN];
3232        __u32 ifindex;
3233        __u32 gpl_compatible:1;
3234        __u32 :31; /* alignment pad */
3235        __u64 netns_dev;
3236        __u64 netns_ino;
3237        __u32 nr_jited_ksyms;
3238        __u32 nr_jited_func_lens;
3239        __aligned_u64 jited_ksyms;
3240        __aligned_u64 jited_func_lens;
3241        __u32 btf_id;
3242        __u32 func_info_rec_size;
3243        __aligned_u64 func_info;
3244        __u32 nr_func_info;
3245        __u32 nr_line_info;
3246        __aligned_u64 line_info;
3247        __aligned_u64 jited_line_info;
3248        __u32 nr_jited_line_info;
3249        __u32 line_info_rec_size;
3250        __u32 jited_line_info_rec_size;
3251        __u32 nr_prog_tags;
3252        __aligned_u64 prog_tags;
3253        __u64 run_time_ns;
3254        __u64 run_cnt;
3255} __attribute__((aligned(8)));
3256
3257struct bpf_map_info {
3258        __u32 type;
3259        __u32 id;
3260        __u32 key_size;
3261        __u32 value_size;
3262        __u32 max_entries;
3263        __u32 map_flags;
3264        char  name[BPF_OBJ_NAME_LEN];
3265        __u32 ifindex;
3266        __u32 :32;
3267        __u64 netns_dev;
3268        __u64 netns_ino;
3269        __u32 btf_id;
3270        __u32 btf_key_type_id;
3271        __u32 btf_value_type_id;
3272} __attribute__((aligned(8)));
3273
3274struct bpf_btf_info {
3275        __aligned_u64 btf;
3276        __u32 btf_size;
3277        __u32 id;
3278} __attribute__((aligned(8)));
3279
3280/* User bpf_sock_addr struct to access socket fields and sockaddr struct passed
3281 * by user and intended to be used by socket (e.g. to bind to, depends on
3282 * attach attach type).
3283 */
3284struct bpf_sock_addr {
3285        __u32 user_family;      /* Allows 4-byte read, but no write. */
3286        __u32 user_ip4;         /* Allows 1,2,4-byte read and 4-byte write.
3287                                 * Stored in network byte order.
3288                                 */
3289        __u32 user_ip6[4];      /* Allows 1,2,4,8-byte read and 4,8-byte write.
3290                                 * Stored in network byte order.
3291                                 */
3292        __u32 user_port;        /* Allows 4-byte read and write.
3293                                 * Stored in network byte order
3294                                 */
3295        __u32 family;           /* Allows 4-byte read, but no write */
3296        __u32 type;             /* Allows 4-byte read, but no write */
3297        __u32 protocol;         /* Allows 4-byte read, but no write */
3298        __u32 msg_src_ip4;      /* Allows 1,2,4-byte read and 4-byte write.
3299                                 * Stored in network byte order.
3300                                 */
3301        __u32 msg_src_ip6[4];   /* Allows 1,2,4,8-byte read and 4,8-byte write.
3302                                 * Stored in network byte order.
3303                                 */
3304        __bpf_md_ptr(struct bpf_sock *, sk);
3305};
3306
3307/* User bpf_sock_ops struct to access socket values and specify request ops
3308 * and their replies.
3309 * Some of this fields are in network (bigendian) byte order and may need
3310 * to be converted before use (bpf_ntohl() defined in samples/bpf/bpf_endian.h).
3311 * New fields can only be added at the end of this structure
3312 */
3313struct bpf_sock_ops {
3314        __u32 op;
3315        union {
3316                __u32 args[4];          /* Optionally passed to bpf program */
3317                __u32 reply;            /* Returned by bpf program          */
3318                __u32 replylong[4];     /* Optionally returned by bpf prog  */
3319        };
3320        __u32 family;
3321        __u32 remote_ip4;       /* Stored in network byte order */
3322        __u32 local_ip4;        /* Stored in network byte order */
3323        __u32 remote_ip6[4];    /* Stored in network byte order */
3324        __u32 local_ip6[4];     /* Stored in network byte order */
3325        __u32 remote_port;      /* Stored in network byte order */
3326        __u32 local_port;       /* stored in host byte order */
3327        __u32 is_fullsock;      /* Some TCP fields are only valid if
3328                                 * there is a full socket. If not, the
3329                                 * fields read as zero.
3330                                 */
3331        __u32 snd_cwnd;
3332        __u32 srtt_us;          /* Averaged RTT << 3 in usecs */
3333        __u32 bpf_sock_ops_cb_flags; /* flags defined in uapi/linux/tcp.h */
3334        __u32 state;
3335        __u32 rtt_min;
3336        __u32 snd_ssthresh;
3337        __u32 rcv_nxt;
3338        __u32 snd_nxt;
3339        __u32 snd_una;
3340        __u32 mss_cache;
3341        __u32 ecn_flags;
3342        __u32 rate_delivered;
3343        __u32 rate_interval_us;
3344        __u32 packets_out;
3345        __u32 retrans_out;
3346        __u32 total_retrans;
3347        __u32 segs_in;
3348        __u32 data_segs_in;
3349        __u32 segs_out;
3350        __u32 data_segs_out;
3351        __u32 lost_out;
3352        __u32 sacked_out;
3353        __u32 sk_txhash;
3354        __u64 bytes_received;
3355        __u64 bytes_acked;
3356        __bpf_md_ptr(struct bpf_sock *, sk);
3357};
3358
3359/* Definitions for bpf_sock_ops_cb_flags */
3360#define BPF_SOCK_OPS_RTO_CB_FLAG        (1<<0)
3361#define BPF_SOCK_OPS_RETRANS_CB_FLAG    (1<<1)
3362#define BPF_SOCK_OPS_STATE_CB_FLAG      (1<<2)
3363#define BPF_SOCK_OPS_RTT_CB_FLAG        (1<<3)
3364#define BPF_SOCK_OPS_ALL_CB_FLAGS       0xF             /* Mask of all currently
3365                                                         * supported cb flags
3366                                                         */
3367
3368/* List of known BPF sock_ops operators.
3369 * New entries can only be added at the end
3370 */
3371enum {
3372        BPF_SOCK_OPS_VOID,
3373        BPF_SOCK_OPS_TIMEOUT_INIT,      /* Should return SYN-RTO value to use or
3374                                         * -1 if default value should be used
3375                                         */
3376        BPF_SOCK_OPS_RWND_INIT,         /* Should return initial advertized
3377                                         * window (in packets) or -1 if default
3378                                         * value should be used
3379                                         */
3380        BPF_SOCK_OPS_TCP_CONNECT_CB,    /* Calls BPF program right before an
3381                                         * active connection is initialized
3382                                         */
3383        BPF_SOCK_OPS_ACTIVE_ESTABLISHED_CB,     /* Calls BPF program when an
3384                                                 * active connection is
3385                                                 * established
3386                                                 */
3387        BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB,    /* Calls BPF program when a
3388                                                 * passive connection is
3389                                                 * established
3390                                                 */
3391        BPF_SOCK_OPS_NEEDS_ECN,         /* If connection's congestion control
3392                                         * needs ECN
3393                                         */
3394        BPF_SOCK_OPS_BASE_RTT,          /* Get base RTT. The correct value is
3395                                         * based on the path and may be
3396                                         * dependent on the congestion control
3397                                         * algorithm. In general it indicates
3398                                         * a congestion threshold. RTTs above
3399                                         * this indicate congestion
3400                                         */
3401        BPF_SOCK_OPS_RTO_CB,            /* Called when an RTO has triggered.
3402                                         * Arg1: value of icsk_retransmits
3403                                         * Arg2: value of icsk_rto
3404                                         * Arg3: whether RTO has expired
3405                                         */
3406        BPF_SOCK_OPS_RETRANS_CB,        /* Called when skb is retransmitted.
3407                                         * Arg1: sequence number of 1st byte
3408                                         * Arg2: # segments
3409                                         * Arg3: return value of
3410                                         *       tcp_transmit_skb (0 => success)
3411                                         */
3412        BPF_SOCK_OPS_STATE_CB,          /* Called when TCP changes state.
3413                                         * Arg1: old_state
3414                                         * Arg2: new_state
3415                                         */
3416        BPF_SOCK_OPS_TCP_LISTEN_CB,     /* Called on listen(2), right after
3417                                         * socket transition to LISTEN state.
3418                                         */
3419        BPF_SOCK_OPS_RTT_CB,            /* Called on every RTT.
3420                                         */
3421};
3422
3423/* List of TCP states. There is a build check in net/ipv4/tcp.c to detect
3424 * changes between the TCP and BPF versions. Ideally this should never happen.
3425 * If it does, we need to add code to convert them before calling
3426 * the BPF sock_ops function.
3427 */
3428enum {
3429        BPF_TCP_ESTABLISHED = 1,
3430        BPF_TCP_SYN_SENT,
3431        BPF_TCP_SYN_RECV,
3432        BPF_TCP_FIN_WAIT1,
3433        BPF_TCP_FIN_WAIT2,
3434        BPF_TCP_TIME_WAIT,
3435        BPF_TCP_CLOSE,
3436        BPF_TCP_CLOSE_WAIT,
3437        BPF_TCP_LAST_ACK,
3438        BPF_TCP_LISTEN,
3439        BPF_TCP_CLOSING,        /* Now a valid state */
3440        BPF_TCP_NEW_SYN_RECV,
3441
3442        BPF_TCP_MAX_STATES      /* Leave at the end! */
3443};
3444
3445#define TCP_BPF_IW              1001    /* Set TCP initial congestion window */
3446#define TCP_BPF_SNDCWND_CLAMP   1002    /* Set sndcwnd_clamp */
3447
3448struct bpf_perf_event_value {
3449        __u64 counter;
3450        __u64 enabled;
3451        __u64 running;
3452};
3453
3454#define BPF_DEVCG_ACC_MKNOD     (1ULL << 0)
3455#define BPF_DEVCG_ACC_READ      (1ULL << 1)
3456#define BPF_DEVCG_ACC_WRITE     (1ULL << 2)
3457
3458#define BPF_DEVCG_DEV_BLOCK     (1ULL << 0)
3459#define BPF_DEVCG_DEV_CHAR      (1ULL << 1)
3460
3461struct bpf_cgroup_dev_ctx {
3462        /* access_type encoded as (BPF_DEVCG_ACC_* << 16) | BPF_DEVCG_DEV_* */
3463        __u32 access_type;
3464        __u32 major;
3465        __u32 minor;
3466};
3467
3468struct bpf_raw_tracepoint_args {
3469        __u64 args[0];
3470};
3471
3472/* DIRECT:  Skip the FIB rules and go to FIB table associated with device
3473 * OUTPUT:  Do lookup from egress perspective; default is ingress
3474 */
3475#define BPF_FIB_LOOKUP_DIRECT  (1U << 0)
3476#define BPF_FIB_LOOKUP_OUTPUT  (1U << 1)
3477
3478enum {
3479        BPF_FIB_LKUP_RET_SUCCESS,      /* lookup successful */
3480        BPF_FIB_LKUP_RET_BLACKHOLE,    /* dest is blackholed; can be dropped */
3481        BPF_FIB_LKUP_RET_UNREACHABLE,  /* dest is unreachable; can be dropped */
3482        BPF_FIB_LKUP_RET_PROHIBIT,     /* dest not allowed; can be dropped */
3483        BPF_FIB_LKUP_RET_NOT_FWDED,    /* packet is not forwarded */
3484        BPF_FIB_LKUP_RET_FWD_DISABLED, /* fwding is not enabled on ingress */
3485        BPF_FIB_LKUP_RET_UNSUPP_LWT,   /* fwd requires encapsulation */
3486        BPF_FIB_LKUP_RET_NO_NEIGH,     /* no neighbor entry for nh */
3487        BPF_FIB_LKUP_RET_FRAG_NEEDED,  /* fragmentation required to fwd */
3488};
3489
3490struct bpf_fib_lookup {
3491        /* input:  network family for lookup (AF_INET, AF_INET6)
3492         * output: network family of egress nexthop
3493         */
3494        __u8    family;
3495
3496        /* set if lookup is to consider L4 data - e.g., FIB rules */
3497        __u8    l4_protocol;
3498        __be16  sport;
3499        __be16  dport;
3500
3501        /* total length of packet from network header - used for MTU check */
3502        __u16   tot_len;
3503
3504        /* input: L3 device index for lookup
3505         * output: device index from FIB lookup
3506         */
3507        __u32   ifindex;
3508
3509        union {
3510                /* inputs to lookup */
3511                __u8    tos;            /* AF_INET  */
3512                __be32  flowinfo;       /* AF_INET6, flow_label + priority */
3513
3514                /* output: metric of fib result (IPv4/IPv6 only) */
3515                __u32   rt_metric;
3516        };
3517
3518        union {
3519                __be32          ipv4_src;
3520                __u32           ipv6_src[4];  /* in6_addr; network order */
3521        };
3522
3523        /* input to bpf_fib_lookup, ipv{4,6}_dst is destination address in
3524         * network header. output: bpf_fib_lookup sets to gateway address
3525         * if FIB lookup returns gateway route
3526         */
3527        union {
3528                __be32          ipv4_dst;
3529                __u32           ipv6_dst[4];  /* in6_addr; network order */
3530        };
3531
3532        /* output */
3533        __be16  h_vlan_proto;
3534        __be16  h_vlan_TCI;
3535        __u8    smac[6];     /* ETH_ALEN */
3536        __u8    dmac[6];     /* ETH_ALEN */
3537};
3538
3539enum bpf_task_fd_type {
3540        BPF_FD_TYPE_RAW_TRACEPOINT,     /* tp name */
3541        BPF_FD_TYPE_TRACEPOINT,         /* tp name */
3542        BPF_FD_TYPE_KPROBE,             /* (symbol + offset) or addr */
3543        BPF_FD_TYPE_KRETPROBE,          /* (symbol + offset) or addr */
3544        BPF_FD_TYPE_UPROBE,             /* filename + offset */
3545        BPF_FD_TYPE_URETPROBE,          /* filename + offset */
3546};
3547
3548#define BPF_FLOW_DISSECTOR_F_PARSE_1ST_FRAG             (1U << 0)
3549#define BPF_FLOW_DISSECTOR_F_STOP_AT_FLOW_LABEL         (1U << 1)
3550#define BPF_FLOW_DISSECTOR_F_STOP_AT_ENCAP              (1U << 2)
3551
3552struct bpf_flow_keys {
3553        __u16   nhoff;
3554        __u16   thoff;
3555        __u16   addr_proto;                     /* ETH_P_* of valid addrs */
3556        __u8    is_frag;
3557        __u8    is_first_frag;
3558        __u8    is_encap;
3559        __u8    ip_proto;
3560        __be16  n_proto;
3561        __be16  sport;
3562        __be16  dport;
3563        union {
3564                struct {
3565                        __be32  ipv4_src;
3566                        __be32  ipv4_dst;
3567                };
3568                struct {
3569                        __u32   ipv6_src[4];    /* in6_addr; network order */
3570                        __u32   ipv6_dst[4];    /* in6_addr; network order */
3571                };
3572        };
3573        __u32   flags;
3574        __be32  flow_label;
3575};
3576
3577struct bpf_func_info {
3578        __u32   insn_off;
3579        __u32   type_id;
3580};
3581
3582#define BPF_LINE_INFO_LINE_NUM(line_col)        ((line_col) >> 10)
3583#define BPF_LINE_INFO_LINE_COL(line_col)        ((line_col) & 0x3ff)
3584
3585struct bpf_line_info {
3586        __u32   insn_off;
3587        __u32   file_name_off;
3588        __u32   line_off;
3589        __u32   line_col;
3590};
3591
3592struct bpf_spin_lock {
3593        __u32   val;
3594};
3595
3596struct bpf_sysctl {
3597        __u32   write;          /* Sysctl is being read (= 0) or written (= 1).
3598                                 * Allows 1,2,4-byte read, but no write.
3599                                 */
3600        __u32   file_pos;       /* Sysctl file position to read from, write to.
3601                                 * Allows 1,2,4-byte read an 4-byte write.
3602                                 */
3603};
3604
3605struct bpf_sockopt {
3606        __bpf_md_ptr(struct bpf_sock *, sk);
3607        __bpf_md_ptr(void *, optval);
3608        __bpf_md_ptr(void *, optval_end);
3609
3610        __s32   level;
3611        __s32   optname;
3612        __s32   optlen;
3613        __s32   retval;
3614};
3615
3616#endif /* _UAPI__LINUX_BPF_H__ */
3617