LXR linux/net/dccp/dccp.h

   1#ifndef _DCCP_H
   2#define _DCCP_H
   3/*
   4 *  net/dccp/dccp.h
   5 *
   6 *  An implementation of the DCCP protocol
   7 *  Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@conectiva.com.br>
   8 *  Copyright (c) 2005-6 Ian McDonald <ian.mcdonald@jandi.co.nz>
   9 *
  10 *      This program is free software; you can redistribute it and/or modify it
  11 *      under the terms of the GNU General Public License version 2 as
  12 *      published by the Free Software Foundation.
  13 */
  14
  15#include <linux/dccp.h>
  16#include <linux/ktime.h>
  17#include <net/snmp.h>
  18#include <net/sock.h>
  19#include <net/tcp.h>
  20#include "ackvec.h"
  21
  22/*
  23 *      DCCP - specific warning and debugging macros.
  24 */
  25#define DCCP_WARN(fmt, ...)                                             \
  26        net_warn_ratelimited("%s: " fmt, __func__, ##__VA_ARGS__)
  27#define DCCP_CRIT(fmt, a...) printk(KERN_CRIT fmt " at %s:%d/%s()\n", ##a, \
  28                                         __FILE__, __LINE__, __func__)
  29#define DCCP_BUG(a...)       do { DCCP_CRIT("BUG: " a); dump_stack(); } while(0)
  30#define DCCP_BUG_ON(cond)    do { if (unlikely((cond) != 0))               \
  31                                     DCCP_BUG("\"%s\" holds (exception!)", \
  32                                              __stringify(cond));          \
  33                             } while (0)
  34
  35#define DCCP_PRINTK(enable, fmt, args...)       do { if (enable)             \
  36                                                        printk(fmt, ##args); \
  37                                                } while(0)
  38#define DCCP_PR_DEBUG(enable, fmt, a...)        DCCP_PRINTK(enable, KERN_DEBUG \
  39                                                  "%s: " fmt, __func__, ##a)
  40
  41#ifdef CONFIG_IP_DCCP_DEBUG
  42extern bool dccp_debug;
  43#define dccp_pr_debug(format, a...)       DCCP_PR_DEBUG(dccp_debug, format, ##a)
  44#define dccp_pr_debug_cat(format, a...)   DCCP_PRINTK(dccp_debug, format, ##a)
  45#define dccp_debug(fmt, a...)             dccp_pr_debug_cat(KERN_DEBUG fmt, ##a)
  46#else
  47#define dccp_pr_debug(format, a...)
  48#define dccp_pr_debug_cat(format, a...)
  49#define dccp_debug(format, a...)
  50#endif
  51
  52extern struct inet_hashinfo dccp_hashinfo;
  53
  54extern struct percpu_counter dccp_orphan_count;
  55
  56void dccp_time_wait(struct sock *sk, int state, int timeo);
  57
  58/*
  59 *  Set safe upper bounds for header and option length. Since Data Offset is 8
  60 *  bits (RFC 4340, sec. 5.1), the total header length can never be more than
  61 *  4 * 255 = 1020 bytes. The largest possible header length is 28 bytes (X=1):
  62 *    - DCCP-Response with ACK Subheader and 4 bytes of Service code      OR
  63 *    - DCCP-Reset    with ACK Subheader and 4 bytes of Reset Code fields
  64 *  Hence a safe upper bound for the maximum option length is 1020-28 = 992
  65 */
  66#define MAX_DCCP_SPECIFIC_HEADER (255 * sizeof(uint32_t))
  67#define DCCP_MAX_PACKET_HDR 28
  68#define DCCP_MAX_OPT_LEN (MAX_DCCP_SPECIFIC_HEADER - DCCP_MAX_PACKET_HDR)
  69#define MAX_DCCP_HEADER (MAX_DCCP_SPECIFIC_HEADER + MAX_HEADER)
  70
  71/* Upper bound for initial feature-negotiation overhead (padded to 32 bits) */
  72#define DCCP_FEATNEG_OVERHEAD    (32 * sizeof(uint32_t))
  73
  74#define DCCP_TIMEWAIT_LEN (60 * HZ) /* how long to wait to destroy TIME-WAIT
  75                                     * state, about 60 seconds */
  76
  77/* RFC 1122, 4.2.3.1 initial RTO value */
  78#define DCCP_TIMEOUT_INIT ((unsigned int)(3 * HZ))
  79
  80/*
  81 * The maximum back-off value for retransmissions. This is needed for
  82 *  - retransmitting client-Requests (sec. 8.1.1),
  83 *  - retransmitting Close/CloseReq when closing (sec. 8.3),
  84 *  - feature-negotiation retransmission (sec. 6.6.3),
  85 *  - Acks in client-PARTOPEN state (sec. 8.1.5).
  86 */
  87#define DCCP_RTO_MAX ((unsigned int)(64 * HZ))
  88
  89/*
  90 * RTT sampling: sanity bounds and fallback RTT value from RFC 4340, section 3.4
  91 */
  92#define DCCP_SANE_RTT_MIN       100
  93#define DCCP_FALLBACK_RTT       (USEC_PER_SEC / 5)
  94#define DCCP_SANE_RTT_MAX       (3 * USEC_PER_SEC)
  95
  96/* sysctl variables for DCCP */
  97extern int  sysctl_dccp_request_retries;
  98extern int  sysctl_dccp_retries1;
  99extern int  sysctl_dccp_retries2;
 100extern int  sysctl_dccp_tx_qlen;
 101extern int  sysctl_dccp_sync_ratelimit;
 102
 103/*
 104 *      48-bit sequence number arithmetic (signed and unsigned)
 105 */
 106#define INT48_MIN         0x800000000000LL              /* 2^47     */
 107#define UINT48_MAX        0xFFFFFFFFFFFFLL              /* 2^48 - 1 */
 108#define COMPLEMENT48(x)  (0x1000000000000LL - (x))      /* 2^48 - x */
 109#define TO_SIGNED48(x)   (((x) < INT48_MIN)? (x) : -COMPLEMENT48( (x)))
 110#define TO_UNSIGNED48(x) (((x) >= 0)?        (x) :  COMPLEMENT48(-(x)))
 111#define ADD48(a, b)      (((a) + (b)) & UINT48_MAX)
 112#define SUB48(a, b)      ADD48((a), COMPLEMENT48(b))
 113
 114static inline void dccp_set_seqno(u64 *seqno, u64 value)
 115{
 116        *seqno = value & UINT48_MAX;
 117}
 118
 119static inline void dccp_inc_seqno(u64 *seqno)
 120{
 121        *seqno = ADD48(*seqno, 1);
 122}
 123
 124/* signed mod-2^48 distance: pos. if seqno1 < seqno2, neg. if seqno1 > seqno2 */
 125static inline s64 dccp_delta_seqno(const u64 seqno1, const u64 seqno2)
 126{
 127        u64 delta = SUB48(seqno2, seqno1);
 128
 129        return TO_SIGNED48(delta);
 130}
 131
 132/* is seq1 < seq2 ? */
 133static inline int before48(const u64 seq1, const u64 seq2)
 134{
 135        return (s64)((seq2 << 16) - (seq1 << 16)) > 0;
 136}
 137
 138/* is seq1 > seq2 ? */
 139#define after48(seq1, seq2)     before48(seq2, seq1)
 140
 141/* is seq2 <= seq1 <= seq3 ? */
 142static inline int between48(const u64 seq1, const u64 seq2, const u64 seq3)
 143{
 144        return (seq3 << 16) - (seq2 << 16) >= (seq1 << 16) - (seq2 << 16);
 145}
 146
 147static inline u64 max48(const u64 seq1, const u64 seq2)
 148{
 149        return after48(seq1, seq2) ? seq1 : seq2;
 150}
 151
 152/**
 153 * dccp_loss_count - Approximate the number of lost data packets in a burst loss
 154 * @s1:  last known sequence number before the loss ('hole')
 155 * @s2:  first sequence number seen after the 'hole'
 156 * @ndp: NDP count on packet with sequence number @s2
 157 */
 158static inline u64 dccp_loss_count(const u64 s1, const u64 s2, const u64 ndp)
 159{
 160        s64 delta = dccp_delta_seqno(s1, s2);
 161
 162        WARN_ON(delta < 0);
 163        delta -= ndp + 1;
 164
 165        return delta > 0 ? delta : 0;
 166}
 167
 168/**
 169 * dccp_loss_free - Evaluate condition for data loss from RFC 4340, 7.7.1
 170 */
 171static inline bool dccp_loss_free(const u64 s1, const u64 s2, const u64 ndp)
 172{
 173        return dccp_loss_count(s1, s2, ndp) == 0;
 174}
 175
 176enum {
 177        DCCP_MIB_NUM = 0,
 178        DCCP_MIB_ACTIVEOPENS,                   /* ActiveOpens */
 179        DCCP_MIB_ESTABRESETS,                   /* EstabResets */
 180        DCCP_MIB_CURRESTAB,                     /* CurrEstab */
 181        DCCP_MIB_OUTSEGS,                       /* OutSegs */
 182        DCCP_MIB_OUTRSTS,
 183        DCCP_MIB_ABORTONTIMEOUT,
 184        DCCP_MIB_TIMEOUTS,
 185        DCCP_MIB_ABORTFAILED,
 186        DCCP_MIB_PASSIVEOPENS,
 187        DCCP_MIB_ATTEMPTFAILS,
 188        DCCP_MIB_OUTDATAGRAMS,
 189        DCCP_MIB_INERRS,
 190        DCCP_MIB_OPTMANDATORYERROR,
 191        DCCP_MIB_INVALIDOPT,
 192        __DCCP_MIB_MAX
 193};
 194
 195#define DCCP_MIB_MAX    __DCCP_MIB_MAX
 196struct dccp_mib {
 197        unsigned long   mibs[DCCP_MIB_MAX];
 198};
 199
 200DECLARE_SNMP_STAT(struct dccp_mib, dccp_statistics);
 201#define DCCP_INC_STATS(field)       SNMP_INC_STATS(dccp_statistics, field)
 202#define DCCP_INC_STATS_BH(field)    SNMP_INC_STATS_BH(dccp_statistics, field)
 203#define DCCP_DEC_STATS(field)       SNMP_DEC_STATS(dccp_statistics, field)
 204
 205/*
 206 *      Checksumming routines
 207 */
 208static inline unsigned int dccp_csum_coverage(const struct sk_buff *skb)
 209{
 210        const struct dccp_hdr* dh = dccp_hdr(skb);
 211
 212        if (dh->dccph_cscov == 0)
 213                return skb->len;
 214        return (dh->dccph_doff + dh->dccph_cscov - 1) * sizeof(u32);
 215}
 216
 217static inline void dccp_csum_outgoing(struct sk_buff *skb)
 218{
 219        unsigned int cov = dccp_csum_coverage(skb);
 220
 221        if (cov >= skb->len)
 222                dccp_hdr(skb)->dccph_cscov = 0;
 223
 224        skb->csum = skb_checksum(skb, 0, (cov > skb->len)? skb->len : cov, 0);
 225}
 226
 227void dccp_v4_send_check(struct sock *sk, struct sk_buff *skb);
 228
 229int dccp_retransmit_skb(struct sock *sk);
 230
 231void dccp_send_ack(struct sock *sk);
 232void dccp_reqsk_send_ack(struct sock *sk, struct sk_buff *skb,
 233                         struct request_sock *rsk);
 234
 235void dccp_send_sync(struct sock *sk, const u64 seq,
 236                    const enum dccp_pkt_type pkt_type);
 237
 238/*
 239 * TX Packet Dequeueing Interface
 240 */
 241void dccp_qpolicy_push(struct sock *sk, struct sk_buff *skb);
 242bool dccp_qpolicy_full(struct sock *sk);
 243void dccp_qpolicy_drop(struct sock *sk, struct sk_buff *skb);
 244struct sk_buff *dccp_qpolicy_top(struct sock *sk);
 245struct sk_buff *dccp_qpolicy_pop(struct sock *sk);
 246bool dccp_qpolicy_param_ok(struct sock *sk, __be32 param);
 247
 248/*
 249 * TX Packet Output and TX Timers
 250 */
 251void dccp_write_xmit(struct sock *sk);
 252void dccp_write_space(struct sock *sk);
 253void dccp_flush_write_queue(struct sock *sk, long *time_budget);
 254
 255void dccp_init_xmit_timers(struct sock *sk);
 256static inline void dccp_clear_xmit_timers(struct sock *sk)
 257{
 258        inet_csk_clear_xmit_timers(sk);
 259}
 260
 261unsigned int dccp_sync_mss(struct sock *sk, u32 pmtu);
 262
 263const char *dccp_packet_name(const int type);
 264
 265void dccp_set_state(struct sock *sk, const int state);
 266void dccp_done(struct sock *sk);
 267
 268int dccp_reqsk_init(struct request_sock *rq, struct dccp_sock const *dp,
 269                    struct sk_buff const *skb);
 270
 271int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb);
 272
 273struct sock *dccp_create_openreq_child(struct sock *sk,
 274                                       const struct request_sock *req,
 275                                       const struct sk_buff *skb);
 276
 277int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb);
 278
 279struct sock *dccp_v4_request_recv_sock(struct sock *sk, struct sk_buff *skb,
 280                                       struct request_sock *req,
 281                                       struct dst_entry *dst);
 282struct sock *dccp_check_req(struct sock *sk, struct sk_buff *skb,
 283                            struct request_sock *req);
 284
 285int dccp_child_process(struct sock *parent, struct sock *child,
 286                       struct sk_buff *skb);
 287int dccp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
 288                           struct dccp_hdr *dh, unsigned int len);
 289int dccp_rcv_established(struct sock *sk, struct sk_buff *skb,
 290                         const struct dccp_hdr *dh, const unsigned int len);
 291
 292int dccp_init_sock(struct sock *sk, const __u8 ctl_sock_initialized);
 293void dccp_destroy_sock(struct sock *sk);
 294
 295void dccp_close(struct sock *sk, long timeout);
 296struct sk_buff *dccp_make_response(struct sock *sk, struct dst_entry *dst,
 297                                   struct request_sock *req);
 298
 299int dccp_connect(struct sock *sk);
 300int dccp_disconnect(struct sock *sk, int flags);
 301int dccp_getsockopt(struct sock *sk, int level, int optname,
 302                    char __user *optval, int __user *optlen);
 303int dccp_setsockopt(struct sock *sk, int level, int optname,
 304                    char __user *optval, unsigned int optlen);
 305#ifdef CONFIG_COMPAT
 306int compat_dccp_getsockopt(struct sock *sk, int level, int optname,
 307                           char __user *optval, int __user *optlen);
 308int compat_dccp_setsockopt(struct sock *sk, int level, int optname,
 309                           char __user *optval, unsigned int optlen);
 310#endif
 311int dccp_ioctl(struct sock *sk, int cmd, unsigned long arg);
 312int dccp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size);
 313int dccp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int nonblock,
 314                 int flags, int *addr_len);
 315void dccp_shutdown(struct sock *sk, int how);
 316int inet_dccp_listen(struct socket *sock, int backlog);
 317unsigned int dccp_poll(struct file *file, struct socket *sock,
 318                       poll_table *wait);
 319int dccp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len);
 320void dccp_req_err(struct sock *sk, u64 seq);
 321
 322struct sk_buff *dccp_ctl_make_reset(struct sock *sk, struct sk_buff *skb);
 323int dccp_send_reset(struct sock *sk, enum dccp_reset_codes code);
 324void dccp_send_close(struct sock *sk, const int active);
 325int dccp_invalid_packet(struct sk_buff *skb);
 326u32 dccp_sample_rtt(struct sock *sk, long delta);
 327
 328static inline int dccp_bad_service_code(const struct sock *sk,
 329                                        const __be32 service)
 330{
 331        const struct dccp_sock *dp = dccp_sk(sk);
 332
 333        if (dp->dccps_service == service)
 334                return 0;
 335        return !dccp_list_has_service(dp->dccps_service_list, service);
 336}
 337
 338/**
 339 * dccp_skb_cb  -  DCCP per-packet control information
 340 * @dccpd_type: one of %dccp_pkt_type (or unknown)
 341 * @dccpd_ccval: CCVal field (5.1), see e.g. RFC 4342, 8.1
 342 * @dccpd_reset_code: one of %dccp_reset_codes
 343 * @dccpd_reset_data: Data1..3 fields (depend on @dccpd_reset_code)
 344 * @dccpd_opt_len: total length of all options (5.8) in the packet
 345 * @dccpd_seq: sequence number
 346 * @dccpd_ack_seq: acknowledgment number subheader field value
 347 *
 348 * This is used for transmission as well as for reception.
 349 */
 350struct dccp_skb_cb {
 351        union {
 352                struct inet_skb_parm    h4;
 353#if IS_ENABLED(CONFIG_IPV6)
 354                struct inet6_skb_parm   h6;
 355#endif
 356        } header;
 357        __u8  dccpd_type:4;
 358        __u8  dccpd_ccval:4;
 359        __u8  dccpd_reset_code,
 360              dccpd_reset_data[3];
 361        __u16 dccpd_opt_len;
 362        __u64 dccpd_seq;
 363        __u64 dccpd_ack_seq;
 364};
 365
 366#define DCCP_SKB_CB(__skb) ((struct dccp_skb_cb *)&((__skb)->cb[0]))
 367
 368/* RFC 4340, sec. 7.7 */
 369static inline int dccp_non_data_packet(const struct sk_buff *skb)
 370{
 371        const __u8 type = DCCP_SKB_CB(skb)->dccpd_type;
 372
 373        return type == DCCP_PKT_ACK      ||
 374               type == DCCP_PKT_CLOSE    ||
 375               type == DCCP_PKT_CLOSEREQ ||
 376               type == DCCP_PKT_RESET    ||
 377               type == DCCP_PKT_SYNC     ||
 378               type == DCCP_PKT_SYNCACK;
 379}
 380
 381/* RFC 4340, sec. 7.7 */
 382static inline int dccp_data_packet(const struct sk_buff *skb)
 383{
 384        const __u8 type = DCCP_SKB_CB(skb)->dccpd_type;
 385
 386        return type == DCCP_PKT_DATA     ||
 387               type == DCCP_PKT_DATAACK  ||
 388               type == DCCP_PKT_REQUEST  ||
 389               type == DCCP_PKT_RESPONSE;
 390}
 391
 392static inline int dccp_packet_without_ack(const struct sk_buff *skb)
 393{
 394        const __u8 type = DCCP_SKB_CB(skb)->dccpd_type;
 395
 396        return type == DCCP_PKT_DATA || type == DCCP_PKT_REQUEST;
 397}
 398
 399#define DCCP_PKT_WITHOUT_ACK_SEQ (UINT48_MAX << 2)
 400
 401static inline void dccp_hdr_set_seq(struct dccp_hdr *dh, const u64 gss)
 402{
 403        struct dccp_hdr_ext *dhx = (struct dccp_hdr_ext *)((void *)dh +
 404                                                           sizeof(*dh));
 405        dh->dccph_seq2 = 0;
 406        dh->dccph_seq = htons((gss >> 32) & 0xfffff);
 407        dhx->dccph_seq_low = htonl(gss & 0xffffffff);
 408}
 409
 410static inline void dccp_hdr_set_ack(struct dccp_hdr_ack_bits *dhack,
 411                                    const u64 gsr)
 412{
 413        dhack->dccph_reserved1 = 0;
 414        dhack->dccph_ack_nr_high = htons(gsr >> 32);
 415        dhack->dccph_ack_nr_low  = htonl(gsr & 0xffffffff);
 416}
 417
 418static inline void dccp_update_gsr(struct sock *sk, u64 seq)
 419{
 420        struct dccp_sock *dp = dccp_sk(sk);
 421
 422        if (after48(seq, dp->dccps_gsr))
 423                dp->dccps_gsr = seq;
 424        /* Sequence validity window depends on remote Sequence Window (7.5.1) */
 425        dp->dccps_swl = SUB48(ADD48(dp->dccps_gsr, 1), dp->dccps_r_seq_win / 4);
 426        /*
 427         * Adjust SWL so that it is not below ISR. In contrast to RFC 4340,
 428         * 7.5.1 we perform this check beyond the initial handshake: W/W' are
 429         * always > 32, so for the first W/W' packets in the lifetime of a
 430         * connection we always have to adjust SWL.
 431         * A second reason why we are doing this is that the window depends on
 432         * the feature-remote value of Sequence Window: nothing stops the peer
 433         * from updating this value while we are busy adjusting SWL for the
 434         * first W packets (we would have to count from scratch again then).
 435         * Therefore it is safer to always make sure that the Sequence Window
 436         * is not artificially extended by a peer who grows SWL downwards by
 437         * continually updating the feature-remote Sequence-Window.
 438         * If sequence numbers wrap it is bad luck. But that will take a while
 439         * (48 bit), and this measure prevents Sequence-number attacks.
 440         */
 441        if (before48(dp->dccps_swl, dp->dccps_isr))
 442                dp->dccps_swl = dp->dccps_isr;
 443        dp->dccps_swh = ADD48(dp->dccps_gsr, (3 * dp->dccps_r_seq_win) / 4);
 444}
 445
 446static inline void dccp_update_gss(struct sock *sk, u64 seq)
 447{
 448        struct dccp_sock *dp = dccp_sk(sk);
 449
 450        dp->dccps_gss = seq;
 451        /* Ack validity window depends on local Sequence Window value (7.5.1) */
 452        dp->dccps_awl = SUB48(ADD48(dp->dccps_gss, 1), dp->dccps_l_seq_win);
 453        /* Adjust AWL so that it is not below ISS - see comment above for SWL */
 454        if (before48(dp->dccps_awl, dp->dccps_iss))
 455                dp->dccps_awl = dp->dccps_iss;
 456        dp->dccps_awh = dp->dccps_gss;
 457}
 458
 459static inline int dccp_ackvec_pending(const struct sock *sk)
 460{
 461        return dccp_sk(sk)->dccps_hc_rx_ackvec != NULL &&
 462               !dccp_ackvec_is_empty(dccp_sk(sk)->dccps_hc_rx_ackvec);
 463}
 464
 465static inline int dccp_ack_pending(const struct sock *sk)
 466{
 467        return dccp_ackvec_pending(sk) || inet_csk_ack_scheduled(sk);
 468}
 469
 470int dccp_feat_signal_nn_change(struct sock *sk, u8 feat, u64 nn_val);
 471int dccp_feat_finalise_settings(struct dccp_sock *dp);
 472int dccp_feat_server_ccid_dependencies(struct dccp_request_sock *dreq);
 473int dccp_feat_insert_opts(struct dccp_sock*, struct dccp_request_sock*,
 474                          struct sk_buff *skb);
 475int dccp_feat_activate_values(struct sock *sk, struct list_head *fn);
 476void dccp_feat_list_purge(struct list_head *fn_list);
 477
 478int dccp_insert_options(struct sock *sk, struct sk_buff *skb);
 479int dccp_insert_options_rsk(struct dccp_request_sock *, struct sk_buff *);
 480u32 dccp_timestamp(void);
 481void dccp_timestamping_init(void);
 482int dccp_insert_option(struct sk_buff *skb, unsigned char option,
 483                       const void *value, unsigned char len);
 484
 485#ifdef CONFIG_SYSCTL
 486int dccp_sysctl_init(void);
 487void dccp_sysctl_exit(void);
 488#else
 489static inline int dccp_sysctl_init(void)
 490{
 491        return 0;
 492}
 493
 494static inline void dccp_sysctl_exit(void)
 495{
 496}
 497#endif
 498
 499#endif /* _DCCP_H */
 500