linux/net/dccp/dccp.h
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   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, a...) LIMIT_NETDEBUG(KERN_WARNING "%s: " fmt,       \
  26                                                        __func__, ##a)
  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
  56extern void 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
 227extern void dccp_v4_send_check(struct sock *sk, struct sk_buff *skb);
 228
 229extern int  dccp_retransmit_skb(struct sock *sk);
 230
 231extern void dccp_send_ack(struct sock *sk);
 232extern void dccp_reqsk_send_ack(struct sock *sk, struct sk_buff *skb,
 233                                struct request_sock *rsk);
 234
 235extern void 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 */
 241extern void             dccp_qpolicy_push(struct sock *sk, struct sk_buff *skb);
 242extern bool             dccp_qpolicy_full(struct sock *sk);
 243extern void             dccp_qpolicy_drop(struct sock *sk, struct sk_buff *skb);
 244extern struct sk_buff   *dccp_qpolicy_top(struct sock *sk);
 245extern struct sk_buff   *dccp_qpolicy_pop(struct sock *sk);
 246extern bool             dccp_qpolicy_param_ok(struct sock *sk, __be32 param);
 247
 248/*
 249 * TX Packet Output and TX Timers
 250 */
 251extern void   dccp_write_xmit(struct sock *sk);
 252extern void   dccp_write_space(struct sock *sk);
 253extern void   dccp_flush_write_queue(struct sock *sk, long *time_budget);
 254
 255extern void 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
 261extern unsigned int dccp_sync_mss(struct sock *sk, u32 pmtu);
 262
 263extern const char *dccp_packet_name(const int type);
 264
 265extern void dccp_set_state(struct sock *sk, const int state);
 266extern void dccp_done(struct sock *sk);
 267
 268extern int  dccp_reqsk_init(struct request_sock *rq, struct dccp_sock const *dp,
 269                            struct sk_buff const *skb);
 270
 271extern int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb);
 272
 273extern struct sock *dccp_create_openreq_child(struct sock *sk,
 274                                              const struct request_sock *req,
 275                                              const struct sk_buff *skb);
 276
 277extern int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb);
 278
 279extern struct sock *dccp_v4_request_recv_sock(struct sock *sk,
 280                                              struct sk_buff *skb,
 281                                              struct request_sock *req,
 282                                              struct dst_entry *dst);
 283extern struct sock *dccp_check_req(struct sock *sk, struct sk_buff *skb,
 284                                   struct request_sock *req,
 285                                   struct request_sock **prev);
 286
 287extern int dccp_child_process(struct sock *parent, struct sock *child,
 288                              struct sk_buff *skb);
 289extern int dccp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
 290                                  struct dccp_hdr *dh, unsigned int len);
 291extern int dccp_rcv_established(struct sock *sk, struct sk_buff *skb,
 292                                const struct dccp_hdr *dh, const unsigned int len);
 293
 294extern int dccp_init_sock(struct sock *sk, const __u8 ctl_sock_initialized);
 295extern void dccp_destroy_sock(struct sock *sk);
 296
 297extern void             dccp_close(struct sock *sk, long timeout);
 298extern struct sk_buff   *dccp_make_response(struct sock *sk,
 299                                            struct dst_entry *dst,
 300                                            struct request_sock *req);
 301
 302extern int         dccp_connect(struct sock *sk);
 303extern int         dccp_disconnect(struct sock *sk, int flags);
 304extern int         dccp_getsockopt(struct sock *sk, int level, int optname,
 305                                   char __user *optval, int __user *optlen);
 306extern int         dccp_setsockopt(struct sock *sk, int level, int optname,
 307                                   char __user *optval, unsigned int optlen);
 308#ifdef CONFIG_COMPAT
 309extern int         compat_dccp_getsockopt(struct sock *sk,
 310                                int level, int optname,
 311                                char __user *optval, int __user *optlen);
 312extern int         compat_dccp_setsockopt(struct sock *sk,
 313                                int level, int optname,
 314                                char __user *optval, unsigned int optlen);
 315#endif
 316extern int         dccp_ioctl(struct sock *sk, int cmd, unsigned long arg);
 317extern int         dccp_sendmsg(struct kiocb *iocb, struct sock *sk,
 318                                struct msghdr *msg, size_t size);
 319extern int         dccp_recvmsg(struct kiocb *iocb, struct sock *sk,
 320                                struct msghdr *msg, size_t len, int nonblock,
 321                                int flags, int *addr_len);
 322extern void        dccp_shutdown(struct sock *sk, int how);
 323extern int         inet_dccp_listen(struct socket *sock, int backlog);
 324extern unsigned int dccp_poll(struct file *file, struct socket *sock,
 325                             poll_table *wait);
 326extern int         dccp_v4_connect(struct sock *sk, struct sockaddr *uaddr,
 327                                   int addr_len);
 328
 329extern struct sk_buff *dccp_ctl_make_reset(struct sock *sk,
 330                                           struct sk_buff *skb);
 331extern int         dccp_send_reset(struct sock *sk, enum dccp_reset_codes code);
 332extern void        dccp_send_close(struct sock *sk, const int active);
 333extern int         dccp_invalid_packet(struct sk_buff *skb);
 334extern u32         dccp_sample_rtt(struct sock *sk, long delta);
 335
 336static inline int dccp_bad_service_code(const struct sock *sk,
 337                                        const __be32 service)
 338{
 339        const struct dccp_sock *dp = dccp_sk(sk);
 340
 341        if (dp->dccps_service == service)
 342                return 0;
 343        return !dccp_list_has_service(dp->dccps_service_list, service);
 344}
 345
 346/**
 347 * dccp_skb_cb  -  DCCP per-packet control information
 348 * @dccpd_type: one of %dccp_pkt_type (or unknown)
 349 * @dccpd_ccval: CCVal field (5.1), see e.g. RFC 4342, 8.1
 350 * @dccpd_reset_code: one of %dccp_reset_codes
 351 * @dccpd_reset_data: Data1..3 fields (depend on @dccpd_reset_code)
 352 * @dccpd_opt_len: total length of all options (5.8) in the packet
 353 * @dccpd_seq: sequence number
 354 * @dccpd_ack_seq: acknowledgment number subheader field value
 355 *
 356 * This is used for transmission as well as for reception.
 357 */
 358struct dccp_skb_cb {
 359        union {
 360                struct inet_skb_parm    h4;
 361#if IS_ENABLED(CONFIG_IPV6)
 362                struct inet6_skb_parm   h6;
 363#endif
 364        } header;
 365        __u8  dccpd_type:4;
 366        __u8  dccpd_ccval:4;
 367        __u8  dccpd_reset_code,
 368              dccpd_reset_data[3];
 369        __u16 dccpd_opt_len;
 370        __u64 dccpd_seq;
 371        __u64 dccpd_ack_seq;
 372};
 373
 374#define DCCP_SKB_CB(__skb) ((struct dccp_skb_cb *)&((__skb)->cb[0]))
 375
 376/* RFC 4340, sec. 7.7 */
 377static inline int dccp_non_data_packet(const struct sk_buff *skb)
 378{
 379        const __u8 type = DCCP_SKB_CB(skb)->dccpd_type;
 380
 381        return type == DCCP_PKT_ACK      ||
 382               type == DCCP_PKT_CLOSE    ||
 383               type == DCCP_PKT_CLOSEREQ ||
 384               type == DCCP_PKT_RESET    ||
 385               type == DCCP_PKT_SYNC     ||
 386               type == DCCP_PKT_SYNCACK;
 387}
 388
 389/* RFC 4340, sec. 7.7 */
 390static inline int dccp_data_packet(const struct sk_buff *skb)
 391{
 392        const __u8 type = DCCP_SKB_CB(skb)->dccpd_type;
 393
 394        return type == DCCP_PKT_DATA     ||
 395               type == DCCP_PKT_DATAACK  ||
 396               type == DCCP_PKT_REQUEST  ||
 397               type == DCCP_PKT_RESPONSE;
 398}
 399
 400static inline int dccp_packet_without_ack(const struct sk_buff *skb)
 401{
 402        const __u8 type = DCCP_SKB_CB(skb)->dccpd_type;
 403
 404        return type == DCCP_PKT_DATA || type == DCCP_PKT_REQUEST;
 405}
 406
 407#define DCCP_PKT_WITHOUT_ACK_SEQ (UINT48_MAX << 2)
 408
 409static inline void dccp_hdr_set_seq(struct dccp_hdr *dh, const u64 gss)
 410{
 411        struct dccp_hdr_ext *dhx = (struct dccp_hdr_ext *)((void *)dh +
 412                                                           sizeof(*dh));
 413        dh->dccph_seq2 = 0;
 414        dh->dccph_seq = htons((gss >> 32) & 0xfffff);
 415        dhx->dccph_seq_low = htonl(gss & 0xffffffff);
 416}
 417
 418static inline void dccp_hdr_set_ack(struct dccp_hdr_ack_bits *dhack,
 419                                    const u64 gsr)
 420{
 421        dhack->dccph_reserved1 = 0;
 422        dhack->dccph_ack_nr_high = htons(gsr >> 32);
 423        dhack->dccph_ack_nr_low  = htonl(gsr & 0xffffffff);
 424}
 425
 426static inline void dccp_update_gsr(struct sock *sk, u64 seq)
 427{
 428        struct dccp_sock *dp = dccp_sk(sk);
 429
 430        if (after48(seq, dp->dccps_gsr))
 431                dp->dccps_gsr = seq;
 432        /* Sequence validity window depends on remote Sequence Window (7.5.1) */
 433        dp->dccps_swl = SUB48(ADD48(dp->dccps_gsr, 1), dp->dccps_r_seq_win / 4);
 434        /*
 435         * Adjust SWL so that it is not below ISR. In contrast to RFC 4340,
 436         * 7.5.1 we perform this check beyond the initial handshake: W/W' are
 437         * always > 32, so for the first W/W' packets in the lifetime of a
 438         * connection we always have to adjust SWL.
 439         * A second reason why we are doing this is that the window depends on
 440         * the feature-remote value of Sequence Window: nothing stops the peer
 441         * from updating this value while we are busy adjusting SWL for the
 442         * first W packets (we would have to count from scratch again then).
 443         * Therefore it is safer to always make sure that the Sequence Window
 444         * is not artificially extended by a peer who grows SWL downwards by
 445         * continually updating the feature-remote Sequence-Window.
 446         * If sequence numbers wrap it is bad luck. But that will take a while
 447         * (48 bit), and this measure prevents Sequence-number attacks.
 448         */
 449        if (before48(dp->dccps_swl, dp->dccps_isr))
 450                dp->dccps_swl = dp->dccps_isr;
 451        dp->dccps_swh = ADD48(dp->dccps_gsr, (3 * dp->dccps_r_seq_win) / 4);
 452}
 453
 454static inline void dccp_update_gss(struct sock *sk, u64 seq)
 455{
 456        struct dccp_sock *dp = dccp_sk(sk);
 457
 458        dp->dccps_gss = seq;
 459        /* Ack validity window depends on local Sequence Window value (7.5.1) */
 460        dp->dccps_awl = SUB48(ADD48(dp->dccps_gss, 1), dp->dccps_l_seq_win);
 461        /* Adjust AWL so that it is not below ISS - see comment above for SWL */
 462        if (before48(dp->dccps_awl, dp->dccps_iss))
 463                dp->dccps_awl = dp->dccps_iss;
 464        dp->dccps_awh = dp->dccps_gss;
 465}
 466
 467static inline int dccp_ackvec_pending(const struct sock *sk)
 468{
 469        return dccp_sk(sk)->dccps_hc_rx_ackvec != NULL &&
 470               !dccp_ackvec_is_empty(dccp_sk(sk)->dccps_hc_rx_ackvec);
 471}
 472
 473static inline int dccp_ack_pending(const struct sock *sk)
 474{
 475        return dccp_ackvec_pending(sk) || inet_csk_ack_scheduled(sk);
 476}
 477
 478extern int  dccp_feat_signal_nn_change(struct sock *sk, u8 feat, u64 nn_val);
 479extern int  dccp_feat_finalise_settings(struct dccp_sock *dp);
 480extern int  dccp_feat_server_ccid_dependencies(struct dccp_request_sock *dreq);
 481extern int  dccp_feat_insert_opts(struct dccp_sock*, struct dccp_request_sock*,
 482                                  struct sk_buff *skb);
 483extern int  dccp_feat_activate_values(struct sock *sk, struct list_head *fn);
 484extern void dccp_feat_list_purge(struct list_head *fn_list);
 485
 486extern int dccp_insert_options(struct sock *sk, struct sk_buff *skb);
 487extern int dccp_insert_options_rsk(struct dccp_request_sock*, struct sk_buff*);
 488extern int dccp_insert_option_elapsed_time(struct sk_buff *skb, u32 elapsed);
 489extern u32 dccp_timestamp(void);
 490extern void dccp_timestamping_init(void);
 491extern int dccp_insert_option(struct sk_buff *skb, unsigned char option,
 492                              const void *value, unsigned char len);
 493
 494#ifdef CONFIG_SYSCTL
 495extern int dccp_sysctl_init(void);
 496extern void dccp_sysctl_exit(void);
 497#else
 498static inline int dccp_sysctl_init(void)
 499{
 500        return 0;
 501}
 502
 503static inline void dccp_sysctl_exit(void)
 504{
 505}
 506#endif
 507
 508#endif /* _DCCP_H */
 509
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