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
  42 extern 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
  52 extern struct inet_hashinfo dccp_hashinfo;
  53
  54 extern struct percpu_counter dccp_orphan_count;
  55
  56 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 */
  97 extern int  sysctl_dccp_request_retries;
  98 extern int  sysctl_dccp_retries1;
  99 extern int  sysctl_dccp_retries2;
 100 extern int  sysctl_dccp_tx_qlen;
 101 extern 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
 114 static inline void dccp_set_seqno(u64 *seqno, u64 value)
 115 {
 116         *seqno = value & UINT48_MAX;
 117 }
 118
 119 static 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 */
 125 static 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 ? */
 133 static 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 ? */
 142 static 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
 147 static 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  */
 158 static 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  */
 171 static 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
 176 enum {
 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
 196 struct dccp_mib {
 197         unsigned long   mibs[DCCP_MIB_MAX];
 198 };
 199
 200 DECLARE_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  */
 208 static 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
 217 static 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
 227 void dccp_v4_send_check(struct sock *sk, struct sk_buff *skb);
 228
 229 int dccp_retransmit_skb(struct sock *sk);
 230
 231 void dccp_send_ack(struct sock *sk);
 232 void dccp_reqsk_send_ack(struct sock *sk, struct sk_buff *skb,
 233                          struct request_sock *rsk);
 234
 235 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  */
 241 void dccp_qpolicy_push(struct sock *sk, struct sk_buff *skb);
 242 bool dccp_qpolicy_full(struct sock *sk);
 243 void dccp_qpolicy_drop(struct sock *sk, struct sk_buff *skb);
 244 struct sk_buff *dccp_qpolicy_top(struct sock *sk);
 245 struct sk_buff *dccp_qpolicy_pop(struct sock *sk);
 246 bool dccp_qpolicy_param_ok(struct sock *sk, __be32 param);
 247
 248 /*
 249  * TX Packet Output and TX Timers
 250  */
 251 void dccp_write_xmit(struct sock *sk);
 252 void dccp_write_space(struct sock *sk);
 253 void dccp_flush_write_queue(struct sock *sk, long *time_budget);
 254
 255 void dccp_init_xmit_timers(struct sock *sk);
 256 static inline void dccp_clear_xmit_timers(struct sock *sk)
 257 {
 258         inet_csk_clear_xmit_timers(sk);
 259 }
 260
 261 unsigned int dccp_sync_mss(struct sock *sk, u32 pmtu);
 262
 263 const char *dccp_packet_name(const int type);
 264
 265 void dccp_set_state(struct sock *sk, const int state);
 266 void dccp_done(struct sock *sk);
 267
 268 int dccp_reqsk_init(struct request_sock *rq, struct dccp_sock const *dp,
 269                     struct sk_buff const *skb);
 270
 271 int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb);
 272
 273 struct sock *dccp_create_openreq_child(struct sock *sk,
 274                                        const struct request_sock *req,
 275                                        const struct sk_buff *skb);
 276
 277 int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb);
 278
 279 struct sock *dccp_v4_request_recv_sock(struct sock *sk, struct sk_buff *skb,
 280                                        struct request_sock *req,
 281                                        struct dst_entry *dst);
 282 struct sock *dccp_check_req(struct sock *sk, struct sk_buff *skb,
 283                             struct request_sock *req);
 284
 285 int dccp_child_process(struct sock *parent, struct sock *child,
 286                        struct sk_buff *skb);
 287 int dccp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
 288                            struct dccp_hdr *dh, unsigned int len);
 289 int dccp_rcv_established(struct sock *sk, struct sk_buff *skb,
 290                          const struct dccp_hdr *dh, const unsigned int len);
 291
 292 int dccp_init_sock(struct sock *sk, const __u8 ctl_sock_initialized);
 293 void dccp_destroy_sock(struct sock *sk);
 294
 295 void dccp_close(struct sock *sk, long timeout);
 296 struct sk_buff *dccp_make_response(struct sock *sk, struct dst_entry *dst,
 297                                    struct request_sock *req);
 298
 299 int dccp_connect(struct sock *sk);
 300 int dccp_disconnect(struct sock *sk, int flags);
 301 int dccp_getsockopt(struct sock *sk, int level, int optname,
 302                     char __user *optval, int __user *optlen);
 303 int dccp_setsockopt(struct sock *sk, int level, int optname,
 304                     char __user *optval, unsigned int optlen);
 305 #ifdef CONFIG_COMPAT
 306 int compat_dccp_getsockopt(struct sock *sk, int level, int optname,
 307                            char __user *optval, int __user *optlen);
 308 int compat_dccp_setsockopt(struct sock *sk, int level, int optname,
 309                            char __user *optval, unsigned int optlen);
 310 #endif
 311 int dccp_ioctl(struct sock *sk, int cmd, unsigned long arg);
 312 int dccp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size);
 313 int dccp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int nonblock,
 314                  int flags, int *addr_len);
 315 void dccp_shutdown(struct sock *sk, int how);
 316 int inet_dccp_listen(struct socket *sock, int backlog);
 317 unsigned int dccp_poll(struct file *file, struct socket *sock,
 318                        poll_table *wait);
 319 int dccp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len);
 320 void dccp_req_err(struct sock *sk, u64 seq);
 321
 322 struct sk_buff *dccp_ctl_make_reset(struct sock *sk, struct sk_buff *skb);
 323 int dccp_send_reset(struct sock *sk, enum dccp_reset_codes code);
 324 void dccp_send_close(struct sock *sk, const int active);
 325 int dccp_invalid_packet(struct sk_buff *skb);
 326 u32 dccp_sample_rtt(struct sock *sk, long delta);
 327
 328 static 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  */
 350 struct 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 */
 369 static 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 */
 382 static 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
 392 static 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
 401 static 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
 410 static 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
 418 static 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
 446 static 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
 459 static 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
 465 static inline int dccp_ack_pending(const struct sock *sk)
 466 {
 467         return dccp_ackvec_pending(sk) || inet_csk_ack_scheduled(sk);
 468 }
 469
 470 int dccp_feat_signal_nn_change(struct sock *sk, u8 feat, u64 nn_val);
 471 int dccp_feat_finalise_settings(struct dccp_sock *dp);
 472 int dccp_feat_server_ccid_dependencies(struct dccp_request_sock *dreq);
 473 int dccp_feat_insert_opts(struct dccp_sock*, struct dccp_request_sock*,
 474                           struct sk_buff *skb);
 475 int dccp_feat_activate_values(struct sock *sk, struct list_head *fn);
 476 void dccp_feat_list_purge(struct list_head *fn_list);
 477
 478 int dccp_insert_options(struct sock *sk, struct sk_buff *skb);
 479 int dccp_insert_options_rsk(struct dccp_request_sock *, struct sk_buff *);
 480 u32 dccp_timestamp(void);
 481 void dccp_timestamping_init(void);
 482 int dccp_insert_option(struct sk_buff *skb, unsigned char option,
 483                        const void *value, unsigned char len);
 484
 485 #ifdef CONFIG_SYSCTL
 486 int dccp_sysctl_init(void);
 487 void dccp_sysctl_exit(void);
 488 #else
 489 static inline int dccp_sysctl_init(void)
 490 {
 491         return 0;
 492 }
 493
 494 static inline void dccp_sysctl_exit(void)
 495 {
 496 }
 497 #endif
 498
 499 #endif /* _DCCP_H */