net/dccp/dccp.h

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2 #ifndef _DCCP_H
   3 #define _DCCP_H
   4 /*
   5  *  net/dccp/dccp.h
   6  *
   7  *  An implementation of the DCCP protocol
   8  *  Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@conectiva.com.br>
   9  *  Copyright (c) 2005-6 Ian McDonald <ian.mcdonald@jandi.co.nz>
  10  */
  11
  12 #include <linux/dccp.h>
  13 #include <linux/ktime.h>
  14 #include <net/snmp.h>
  15 #include <net/sock.h>
  16 #include <net/tcp.h>
  17 #include "ackvec.h"
  18
  19 /*
  20  *      DCCP - specific warning and debugging macros.
  21  */
  22 #define DCCP_WARN(fmt, ...)                                             \
  23         net_warn_ratelimited("%s: " fmt, __func__, ##__VA_ARGS__)
  24 #define DCCP_CRIT(fmt, a...) printk(KERN_CRIT fmt " at %s:%d/%s()\n", ##a, \
  25                                          __FILE__, __LINE__, __func__)
  26 #define DCCP_BUG(a...)       do { DCCP_CRIT("BUG: " a); dump_stack(); } while(0)
  27 #define DCCP_BUG_ON(cond)    do { if (unlikely((cond) != 0))               \
  28                                      DCCP_BUG("\"%s\" holds (exception!)", \
  29                                               __stringify(cond));          \
  30                              } while (0)
  31
  32 #define DCCP_PRINTK(enable, fmt, args...)       do { if (enable)             \
  33                                                         printk(fmt, ##args); \
  34                                                 } while(0)
  35 #define DCCP_PR_DEBUG(enable, fmt, a...)        DCCP_PRINTK(enable, KERN_DEBUG \
  36                                                   "%s: " fmt, __func__, ##a)
  37
  38 #ifdef CONFIG_IP_DCCP_DEBUG
  39 extern bool dccp_debug;
  40 #define dccp_pr_debug(format, a...)       DCCP_PR_DEBUG(dccp_debug, format, ##a)
  41 #define dccp_pr_debug_cat(format, a...)   DCCP_PRINTK(dccp_debug, format, ##a)
  42 #define dccp_debug(fmt, a...)             dccp_pr_debug_cat(KERN_DEBUG fmt, ##a)
  43 #else
  44 #define dccp_pr_debug(format, a...)
  45 #define dccp_pr_debug_cat(format, a...)
  46 #define dccp_debug(format, a...)
  47 #endif
  48
  49 extern struct inet_hashinfo dccp_hashinfo;
  50
  51 extern struct percpu_counter dccp_orphan_count;
  52
  53 void dccp_time_wait(struct sock *sk, int state, int timeo);
  54
  55 /*
  56  *  Set safe upper bounds for header and option length. Since Data Offset is 8
  57  *  bits (RFC 4340, sec. 5.1), the total header length can never be more than
  58  *  4 * 255 = 1020 bytes. The largest possible header length is 28 bytes (X=1):
  59  *    - DCCP-Response with ACK Subheader and 4 bytes of Service code      OR
  60  *    - DCCP-Reset    with ACK Subheader and 4 bytes of Reset Code fields
  61  *  Hence a safe upper bound for the maximum option length is 1020-28 = 992
  62  */
  63 #define MAX_DCCP_SPECIFIC_HEADER (255 * sizeof(uint32_t))
  64 #define DCCP_MAX_PACKET_HDR 28
  65 #define DCCP_MAX_OPT_LEN (MAX_DCCP_SPECIFIC_HEADER - DCCP_MAX_PACKET_HDR)
  66 #define MAX_DCCP_HEADER (MAX_DCCP_SPECIFIC_HEADER + MAX_HEADER)
  67
  68 /* Upper bound for initial feature-negotiation overhead (padded to 32 bits) */
  69 #define DCCP_FEATNEG_OVERHEAD    (32 * sizeof(uint32_t))
  70
  71 #define DCCP_TIMEWAIT_LEN (60 * HZ) /* how long to wait to destroy TIME-WAIT
  72                                      * state, about 60 seconds */
  73
  74 /* RFC 1122, 4.2.3.1 initial RTO value */
  75 #define DCCP_TIMEOUT_INIT ((unsigned int)(3 * HZ))
  76
  77 /*
  78  * The maximum back-off value for retransmissions. This is needed for
  79  *  - retransmitting client-Requests (sec. 8.1.1),
  80  *  - retransmitting Close/CloseReq when closing (sec. 8.3),
  81  *  - feature-negotiation retransmission (sec. 6.6.3),
  82  *  - Acks in client-PARTOPEN state (sec. 8.1.5).
  83  */
  84 #define DCCP_RTO_MAX ((unsigned int)(64 * HZ))
  85
  86 /*
  87  * RTT sampling: sanity bounds and fallback RTT value from RFC 4340, section 3.4
  88  */
  89 #define DCCP_SANE_RTT_MIN       100
  90 #define DCCP_FALLBACK_RTT       (USEC_PER_SEC / 5)
  91 #define DCCP_SANE_RTT_MAX       (3 * USEC_PER_SEC)
  92
  93 /* sysctl variables for DCCP */
  94 extern int  sysctl_dccp_request_retries;
  95 extern int  sysctl_dccp_retries1;
  96 extern int  sysctl_dccp_retries2;
  97 extern int  sysctl_dccp_tx_qlen;
  98 extern int  sysctl_dccp_sync_ratelimit;
  99
 100 /*
 101  *      48-bit sequence number arithmetic (signed and unsigned)
 102  */
 103 #define INT48_MIN         0x800000000000LL              /* 2^47     */
 104 #define UINT48_MAX        0xFFFFFFFFFFFFLL              /* 2^48 - 1 */
 105 #define COMPLEMENT48(x)  (0x1000000000000LL - (x))      /* 2^48 - x */
 106 #define TO_SIGNED48(x)   (((x) < INT48_MIN)? (x) : -COMPLEMENT48( (x)))
 107 #define TO_UNSIGNED48(x) (((x) >= 0)?        (x) :  COMPLEMENT48(-(x)))
 108 #define ADD48(a, b)      (((a) + (b)) & UINT48_MAX)
 109 #define SUB48(a, b)      ADD48((a), COMPLEMENT48(b))
 110
 111 static inline void dccp_inc_seqno(u64 *seqno)
 112 {
 113         *seqno = ADD48(*seqno, 1);
 114 }
 115
 116 /* signed mod-2^48 distance: pos. if seqno1 < seqno2, neg. if seqno1 > seqno2 */
 117 static inline s64 dccp_delta_seqno(const u64 seqno1, const u64 seqno2)
 118 {
 119         u64 delta = SUB48(seqno2, seqno1);
 120
 121         return TO_SIGNED48(delta);
 122 }
 123
 124 /* is seq1 < seq2 ? */
 125 static inline int before48(const u64 seq1, const u64 seq2)
 126 {
 127         return (s64)((seq2 << 16) - (seq1 << 16)) > 0;
 128 }
 129
 130 /* is seq1 > seq2 ? */
 131 #define after48(seq1, seq2)     before48(seq2, seq1)
 132
 133 /* is seq2 <= seq1 <= seq3 ? */
 134 static inline int between48(const u64 seq1, const u64 seq2, const u64 seq3)
 135 {
 136         return (seq3 << 16) - (seq2 << 16) >= (seq1 << 16) - (seq2 << 16);
 137 }
 138
 139 static inline u64 max48(const u64 seq1, const u64 seq2)
 140 {
 141         return after48(seq1, seq2) ? seq1 : seq2;
 142 }
 143
 144 /**
 145  * dccp_loss_count - Approximate the number of lost data packets in a burst loss
 146  * @s1:  last known sequence number before the loss ('hole')
 147  * @s2:  first sequence number seen after the 'hole'
 148  * @ndp: NDP count on packet with sequence number @s2
 149  */
 150 static inline u64 dccp_loss_count(const u64 s1, const u64 s2, const u64 ndp)
 151 {
 152         s64 delta = dccp_delta_seqno(s1, s2);
 153
 154         WARN_ON(delta < 0);
 155         delta -= ndp + 1;
 156
 157         return delta > 0 ? delta : 0;
 158 }
 159
 160 /**
 161  * dccp_loss_free - Evaluate condition for data loss from RFC 4340, 7.7.1
 162  */
 163 static inline bool dccp_loss_free(const u64 s1, const u64 s2, const u64 ndp)
 164 {
 165         return dccp_loss_count(s1, s2, ndp) == 0;
 166 }
 167
 168 enum {
 169         DCCP_MIB_NUM = 0,
 170         DCCP_MIB_ACTIVEOPENS,                   /* ActiveOpens */
 171         DCCP_MIB_ESTABRESETS,                   /* EstabResets */
 172         DCCP_MIB_CURRESTAB,                     /* CurrEstab */
 173         DCCP_MIB_OUTSEGS,                       /* OutSegs */
 174         DCCP_MIB_OUTRSTS,
 175         DCCP_MIB_ABORTONTIMEOUT,
 176         DCCP_MIB_TIMEOUTS,
 177         DCCP_MIB_ABORTFAILED,
 178         DCCP_MIB_PASSIVEOPENS,
 179         DCCP_MIB_ATTEMPTFAILS,
 180         DCCP_MIB_OUTDATAGRAMS,
 181         DCCP_MIB_INERRS,
 182         DCCP_MIB_OPTMANDATORYERROR,
 183         DCCP_MIB_INVALIDOPT,
 184         __DCCP_MIB_MAX
 185 };
 186
 187 #define DCCP_MIB_MAX    __DCCP_MIB_MAX
 188 struct dccp_mib {
 189         unsigned long   mibs[DCCP_MIB_MAX];
 190 };
 191
 192 DECLARE_SNMP_STAT(struct dccp_mib, dccp_statistics);
 193 #define DCCP_INC_STATS(field)   SNMP_INC_STATS(dccp_statistics, field)
 194 #define __DCCP_INC_STATS(field) __SNMP_INC_STATS(dccp_statistics, field)
 195 #define DCCP_DEC_STATS(field)   SNMP_DEC_STATS(dccp_statistics, field)
 196
 197 /*
 198  *      Checksumming routines
 199  */
 200 static inline unsigned int dccp_csum_coverage(const struct sk_buff *skb)
 201 {
 202         const struct dccp_hdr* dh = dccp_hdr(skb);
 203
 204         if (dh->dccph_cscov == 0)
 205                 return skb->len;
 206         return (dh->dccph_doff + dh->dccph_cscov - 1) * sizeof(u32);
 207 }
 208
 209 static inline void dccp_csum_outgoing(struct sk_buff *skb)
 210 {
 211         unsigned int cov = dccp_csum_coverage(skb);
 212
 213         if (cov >= skb->len)
 214                 dccp_hdr(skb)->dccph_cscov = 0;
 215
 216         skb->csum = skb_checksum(skb, 0, (cov > skb->len)? skb->len : cov, 0);
 217 }
 218
 219 void dccp_v4_send_check(struct sock *sk, struct sk_buff *skb);
 220
 221 int dccp_retransmit_skb(struct sock *sk);
 222
 223 void dccp_send_ack(struct sock *sk);
 224 void dccp_reqsk_send_ack(const struct sock *sk, struct sk_buff *skb,
 225                          struct request_sock *rsk);
 226
 227 void dccp_send_sync(struct sock *sk, const u64 seq,
 228                     const enum dccp_pkt_type pkt_type);
 229
 230 /*
 231  * TX Packet Dequeueing Interface
 232  */
 233 void dccp_qpolicy_push(struct sock *sk, struct sk_buff *skb);
 234 bool dccp_qpolicy_full(struct sock *sk);
 235 void dccp_qpolicy_drop(struct sock *sk, struct sk_buff *skb);
 236 struct sk_buff *dccp_qpolicy_top(struct sock *sk);
 237 struct sk_buff *dccp_qpolicy_pop(struct sock *sk);
 238 bool dccp_qpolicy_param_ok(struct sock *sk, __be32 param);
 239
 240 /*
 241  * TX Packet Output and TX Timers
 242  */
 243 void dccp_write_xmit(struct sock *sk);
 244 void dccp_write_space(struct sock *sk);
 245 void dccp_flush_write_queue(struct sock *sk, long *time_budget);
 246
 247 void dccp_init_xmit_timers(struct sock *sk);
 248 static inline void dccp_clear_xmit_timers(struct sock *sk)
 249 {
 250         inet_csk_clear_xmit_timers(sk);
 251 }
 252
 253 unsigned int dccp_sync_mss(struct sock *sk, u32 pmtu);
 254
 255 const char *dccp_packet_name(const int type);
 256
 257 void dccp_set_state(struct sock *sk, const int state);
 258 void dccp_done(struct sock *sk);
 259
 260 int dccp_reqsk_init(struct request_sock *rq, struct dccp_sock const *dp,
 261                     struct sk_buff const *skb);
 262
 263 int dccp_v4_conn_request(struct sock *sk, struct sk_buff *skb);
 264
 265 struct sock *dccp_create_openreq_child(const struct sock *sk,
 266                                        const struct request_sock *req,
 267                                        const struct sk_buff *skb);
 268
 269 int dccp_v4_do_rcv(struct sock *sk, struct sk_buff *skb);
 270
 271 struct sock *dccp_v4_request_recv_sock(const struct sock *sk, struct sk_buff *skb,
 272                                        struct request_sock *req,
 273                                        struct dst_entry *dst,
 274                                        struct request_sock *req_unhash,
 275                                        bool *own_req);
 276 struct sock *dccp_check_req(struct sock *sk, struct sk_buff *skb,
 277                             struct request_sock *req);
 278
 279 int dccp_child_process(struct sock *parent, struct sock *child,
 280                        struct sk_buff *skb);
 281 int dccp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
 282                            struct dccp_hdr *dh, unsigned int len);
 283 int dccp_rcv_established(struct sock *sk, struct sk_buff *skb,
 284                          const struct dccp_hdr *dh, const unsigned int len);
 285
 286 int dccp_init_sock(struct sock *sk, const __u8 ctl_sock_initialized);
 287 void dccp_destroy_sock(struct sock *sk);
 288
 289 void dccp_close(struct sock *sk, long timeout);
 290 struct sk_buff *dccp_make_response(const struct sock *sk, struct dst_entry *dst,
 291                                    struct request_sock *req);
 292
 293 int dccp_connect(struct sock *sk);
 294 int dccp_disconnect(struct sock *sk, int flags);
 295 int dccp_getsockopt(struct sock *sk, int level, int optname,
 296                     char __user *optval, int __user *optlen);
 297 int dccp_setsockopt(struct sock *sk, int level, int optname,
 298                     sockptr_t optval, unsigned int optlen);
 299 int dccp_ioctl(struct sock *sk, int cmd, unsigned long arg);
 300 int dccp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size);
 301 int dccp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int nonblock,
 302                  int flags, int *addr_len);
 303 void dccp_shutdown(struct sock *sk, int how);
 304 int inet_dccp_listen(struct socket *sock, int backlog);
 305 __poll_t dccp_poll(struct file *file, struct socket *sock,
 306                        poll_table *wait);
 307 int dccp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len);
 308 void dccp_req_err(struct sock *sk, u64 seq);
 309
 310 struct sk_buff *dccp_ctl_make_reset(struct sock *sk, struct sk_buff *skb);
 311 int dccp_send_reset(struct sock *sk, enum dccp_reset_codes code);
 312 void dccp_send_close(struct sock *sk, const int active);
 313 int dccp_invalid_packet(struct sk_buff *skb);
 314 u32 dccp_sample_rtt(struct sock *sk, long delta);
 315
 316 static inline bool dccp_bad_service_code(const struct sock *sk,
 317                                         const __be32 service)
 318 {
 319         const struct dccp_sock *dp = dccp_sk(sk);
 320
 321         if (dp->dccps_service == service)
 322                 return false;
 323         return !dccp_list_has_service(dp->dccps_service_list, service);
 324 }
 325
 326 /**
 327  * dccp_skb_cb  -  DCCP per-packet control information
 328  * @dccpd_type: one of %dccp_pkt_type (or unknown)
 329  * @dccpd_ccval: CCVal field (5.1), see e.g. RFC 4342, 8.1
 330  * @dccpd_reset_code: one of %dccp_reset_codes
 331  * @dccpd_reset_data: Data1..3 fields (depend on @dccpd_reset_code)
 332  * @dccpd_opt_len: total length of all options (5.8) in the packet
 333  * @dccpd_seq: sequence number
 334  * @dccpd_ack_seq: acknowledgment number subheader field value
 335  *
 336  * This is used for transmission as well as for reception.
 337  */
 338 struct dccp_skb_cb {
 339         union {
 340                 struct inet_skb_parm    h4;
 341 #if IS_ENABLED(CONFIG_IPV6)
 342                 struct inet6_skb_parm   h6;
 343 #endif
 344         } header;
 345         __u8  dccpd_type:4;
 346         __u8  dccpd_ccval:4;
 347         __u8  dccpd_reset_code,
 348               dccpd_reset_data[3];
 349         __u16 dccpd_opt_len;
 350         __u64 dccpd_seq;
 351         __u64 dccpd_ack_seq;
 352 };
 353
 354 #define DCCP_SKB_CB(__skb) ((struct dccp_skb_cb *)&((__skb)->cb[0]))
 355
 356 /* RFC 4340, sec. 7.7 */
 357 static inline int dccp_non_data_packet(const struct sk_buff *skb)
 358 {
 359         const __u8 type = DCCP_SKB_CB(skb)->dccpd_type;
 360
 361         return type == DCCP_PKT_ACK      ||
 362                type == DCCP_PKT_CLOSE    ||
 363                type == DCCP_PKT_CLOSEREQ ||
 364                type == DCCP_PKT_RESET    ||
 365                type == DCCP_PKT_SYNC     ||
 366                type == DCCP_PKT_SYNCACK;
 367 }
 368
 369 /* RFC 4340, sec. 7.7 */
 370 static inline int dccp_data_packet(const struct sk_buff *skb)
 371 {
 372         const __u8 type = DCCP_SKB_CB(skb)->dccpd_type;
 373
 374         return type == DCCP_PKT_DATA     ||
 375                type == DCCP_PKT_DATAACK  ||
 376                type == DCCP_PKT_REQUEST  ||
 377                type == DCCP_PKT_RESPONSE;
 378 }
 379
 380 static inline int dccp_packet_without_ack(const struct sk_buff *skb)
 381 {
 382         const __u8 type = DCCP_SKB_CB(skb)->dccpd_type;
 383
 384         return type == DCCP_PKT_DATA || type == DCCP_PKT_REQUEST;
 385 }
 386
 387 #define DCCP_PKT_WITHOUT_ACK_SEQ (UINT48_MAX << 2)
 388
 389 static inline void dccp_hdr_set_seq(struct dccp_hdr *dh, const u64 gss)
 390 {
 391         struct dccp_hdr_ext *dhx = (struct dccp_hdr_ext *)((void *)dh +
 392                                                            sizeof(*dh));
 393         dh->dccph_seq2 = 0;
 394         dh->dccph_seq = htons((gss >> 32) & 0xfffff);
 395         dhx->dccph_seq_low = htonl(gss & 0xffffffff);
 396 }
 397
 398 static inline void dccp_hdr_set_ack(struct dccp_hdr_ack_bits *dhack,
 399                                     const u64 gsr)
 400 {
 401         dhack->dccph_reserved1 = 0;
 402         dhack->dccph_ack_nr_high = htons(gsr >> 32);
 403         dhack->dccph_ack_nr_low  = htonl(gsr & 0xffffffff);
 404 }
 405
 406 static inline void dccp_update_gsr(struct sock *sk, u64 seq)
 407 {
 408         struct dccp_sock *dp = dccp_sk(sk);
 409
 410         if (after48(seq, dp->dccps_gsr))
 411                 dp->dccps_gsr = seq;
 412         /* Sequence validity window depends on remote Sequence Window (7.5.1) */
 413         dp->dccps_swl = SUB48(ADD48(dp->dccps_gsr, 1), dp->dccps_r_seq_win / 4);
 414         /*
 415          * Adjust SWL so that it is not below ISR. In contrast to RFC 4340,
 416          * 7.5.1 we perform this check beyond the initial handshake: W/W' are
 417          * always > 32, so for the first W/W' packets in the lifetime of a
 418          * connection we always have to adjust SWL.
 419          * A second reason why we are doing this is that the window depends on
 420          * the feature-remote value of Sequence Window: nothing stops the peer
 421          * from updating this value while we are busy adjusting SWL for the
 422          * first W packets (we would have to count from scratch again then).
 423          * Therefore it is safer to always make sure that the Sequence Window
 424          * is not artificially extended by a peer who grows SWL downwards by
 425          * continually updating the feature-remote Sequence-Window.
 426          * If sequence numbers wrap it is bad luck. But that will take a while
 427          * (48 bit), and this measure prevents Sequence-number attacks.
 428          */
 429         if (before48(dp->dccps_swl, dp->dccps_isr))
 430                 dp->dccps_swl = dp->dccps_isr;
 431         dp->dccps_swh = ADD48(dp->dccps_gsr, (3 * dp->dccps_r_seq_win) / 4);
 432 }
 433
 434 static inline void dccp_update_gss(struct sock *sk, u64 seq)
 435 {
 436         struct dccp_sock *dp = dccp_sk(sk);
 437
 438         dp->dccps_gss = seq;
 439         /* Ack validity window depends on local Sequence Window value (7.5.1) */
 440         dp->dccps_awl = SUB48(ADD48(dp->dccps_gss, 1), dp->dccps_l_seq_win);
 441         /* Adjust AWL so that it is not below ISS - see comment above for SWL */
 442         if (before48(dp->dccps_awl, dp->dccps_iss))
 443                 dp->dccps_awl = dp->dccps_iss;
 444         dp->dccps_awh = dp->dccps_gss;
 445 }
 446
 447 static inline int dccp_ackvec_pending(const struct sock *sk)
 448 {
 449         return dccp_sk(sk)->dccps_hc_rx_ackvec != NULL &&
 450                !dccp_ackvec_is_empty(dccp_sk(sk)->dccps_hc_rx_ackvec);
 451 }
 452
 453 static inline int dccp_ack_pending(const struct sock *sk)
 454 {
 455         return dccp_ackvec_pending(sk) || inet_csk_ack_scheduled(sk);
 456 }
 457
 458 int dccp_feat_signal_nn_change(struct sock *sk, u8 feat, u64 nn_val);
 459 int dccp_feat_finalise_settings(struct dccp_sock *dp);
 460 int dccp_feat_server_ccid_dependencies(struct dccp_request_sock *dreq);
 461 int dccp_feat_insert_opts(struct dccp_sock*, struct dccp_request_sock*,
 462                           struct sk_buff *skb);
 463 int dccp_feat_activate_values(struct sock *sk, struct list_head *fn);
 464 void dccp_feat_list_purge(struct list_head *fn_list);
 465
 466 int dccp_insert_options(struct sock *sk, struct sk_buff *skb);
 467 int dccp_insert_options_rsk(struct dccp_request_sock *, struct sk_buff *);
 468 u32 dccp_timestamp(void);
 469 void dccp_timestamping_init(void);
 470 int dccp_insert_option(struct sk_buff *skb, unsigned char option,
 471                        const void *value, unsigned char len);
 472
 473 #ifdef CONFIG_SYSCTL
 474 int dccp_sysctl_init(void);
 475 void dccp_sysctl_exit(void);
 476 #else
 477 static inline int dccp_sysctl_init(void)
 478 {
 479         return 0;
 480 }
 481
 482 static inline void dccp_sysctl_exit(void)
 483 {
 484 }
 485 #endif
 486
 487 #endif /* _DCCP_H */