1 /* SPDX-License-Identifier: GPL-2.0-or-later */ 2 /* 3 * INET An implementation of the TCP/IP protocol suite for the LINUX 4 * operating system. INET is implemented using the BSD Socket 5 * interface as the means of communication with the user level. 6 * 7 * Definitions for the TCP protocol. 8 * 9 * Version: @(#)tcp.h 1.0.2 04/28/93 10 * 11 * Author: Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG> 12 */ 13 #ifndef _LINUX_TCP_H 14 #define _LINUX_TCP_H 15 16 17 #include <linux/skbuff.h> 18 #include <linux/win_minmax.h> 19 #include <net/sock.h> 20 #include <net/inet_connection_sock.h> 21 #include <net/inet_timewait_sock.h> 22 #include <uapi/linux/tcp.h> 23 24 static inline struct tcphdr *tcp_hdr(const struct sk_buff *skb) 25 { 26 return (struct tcphdr *)skb_transport_header(skb); 27 } 28 29 static inline unsigned int __tcp_hdrlen(const struct tcphdr *th) 30 { 31 return th->doff * 4; 32 } 33 34 static inline unsigned int tcp_hdrlen(const struct sk_buff *skb) 35 { 36 return __tcp_hdrlen(tcp_hdr(skb)); 37 } 38 39 static inline struct tcphdr *inner_tcp_hdr(const struct sk_buff *skb) 40 { 41 return (struct tcphdr *)skb_inner_transport_header(skb); 42 } 43 44 static inline unsigned int inner_tcp_hdrlen(const struct sk_buff *skb) 45 { 46 return inner_tcp_hdr(skb)->doff * 4; 47 } 48 49 static inline unsigned int tcp_optlen(const struct sk_buff *skb) 50 { 51 return (tcp_hdr(skb)->doff - 5) * 4; 52 } 53 54 /* TCP Fast Open */ 55 #define TCP_FASTOPEN_COOKIE_MIN 4 /* Min Fast Open Cookie size in bytes */ 56 #define TCP_FASTOPEN_COOKIE_MAX 16 /* Max Fast Open Cookie size in bytes */ 57 #define TCP_FASTOPEN_COOKIE_SIZE 8 /* the size employed by this impl. */ 58 59 /* TCP Fast Open Cookie as stored in memory */ 60 struct tcp_fastopen_cookie { 61 __le64 val[DIV_ROUND_UP(TCP_FASTOPEN_COOKIE_MAX, sizeof(u64))]; 62 s8 len; 63 bool exp; /* In RFC6994 experimental option format */ 64 }; 65 66 /* This defines a selective acknowledgement block. */ 67 struct tcp_sack_block_wire { 68 __be32 start_seq; 69 __be32 end_seq; 70 }; 71 72 struct tcp_sack_block { 73 u32 start_seq; 74 u32 end_seq; 75 }; 76 77 /*These are used to set the sack_ok field in struct tcp_options_received */ 78 #define TCP_SACK_SEEN (1 << 0) /*1 = peer is SACK capable, */ 79 #define TCP_DSACK_SEEN (1 << 2) /*1 = DSACK was received from peer*/ 80 81 struct tcp_options_received { 82 /* PAWS/RTTM data */ 83 int ts_recent_stamp;/* Time we stored ts_recent (for aging) */ 84 u32 ts_recent; /* Time stamp to echo next */ 85 u32 rcv_tsval; /* Time stamp value */ 86 u32 rcv_tsecr; /* Time stamp echo reply */ 87 u16 saw_tstamp : 1, /* Saw TIMESTAMP on last packet */ 88 tstamp_ok : 1, /* TIMESTAMP seen on SYN packet */ 89 dsack : 1, /* D-SACK is scheduled */ 90 wscale_ok : 1, /* Wscale seen on SYN packet */ 91 sack_ok : 3, /* SACK seen on SYN packet */ 92 smc_ok : 1, /* SMC seen on SYN packet */ 93 snd_wscale : 4, /* Window scaling received from sender */ 94 rcv_wscale : 4; /* Window scaling to send to receiver */ 95 u8 saw_unknown:1, /* Received unknown option */ 96 unused:7; 97 u8 num_sacks; /* Number of SACK blocks */ 98 u16 user_mss; /* mss requested by user in ioctl */ 99 u16 mss_clamp; /* Maximal mss, negotiated at connection setup */ 100 }; 101 102 static inline void tcp_clear_options(struct tcp_options_received *rx_opt) 103 { 104 rx_opt->tstamp_ok = rx_opt->sack_ok = 0; 105 rx_opt->wscale_ok = rx_opt->snd_wscale = 0; 106 #if IS_ENABLED(CONFIG_SMC) 107 rx_opt->smc_ok = 0; 108 #endif 109 } 110 111 /* This is the max number of SACKS that we'll generate and process. It's safe 112 * to increase this, although since: 113 * size = TCPOLEN_SACK_BASE_ALIGNED (4) + n * TCPOLEN_SACK_PERBLOCK (8) 114 * only four options will fit in a standard TCP header */ 115 #define TCP_NUM_SACKS 4 116 117 struct tcp_request_sock_ops; 118 119 struct tcp_request_sock { 120 struct inet_request_sock req; 121 const struct tcp_request_sock_ops *af_specific; 122 u64 snt_synack; /* first SYNACK sent time */ 123 bool tfo_listener; 124 bool is_mptcp; 125 #if IS_ENABLED(CONFIG_MPTCP) 126 bool drop_req; 127 #endif 128 u32 txhash; 129 u32 rcv_isn; 130 u32 snt_isn; 131 u32 ts_off; 132 u32 last_oow_ack_time; /* last SYNACK */ 133 u32 rcv_nxt; /* the ack # by SYNACK. For 134 * FastOpen it's the seq# 135 * after data-in-SYN. 136 */ 137 u8 syn_tos; 138 }; 139 140 static inline struct tcp_request_sock *tcp_rsk(const struct request_sock *req) 141 { 142 return (struct tcp_request_sock *)req; 143 } 144 145 struct tcp_sock { 146 /* inet_connection_sock has to be the first member of tcp_sock */ 147 struct inet_connection_sock inet_conn; 148 u16 tcp_header_len; /* Bytes of tcp header to send */ 149 u16 gso_segs; /* Max number of segs per GSO packet */ 150 151 /* 152 * Header prediction flags 153 * 0x5?10 << 16 + snd_wnd in net byte order 154 */ 155 __be32 pred_flags; 156 157 /* 158 * RFC793 variables by their proper names. This means you can 159 * read the code and the spec side by side (and laugh ...) 160 * See RFC793 and RFC1122. The RFC writes these in capitals. 161 */ 162 u64 bytes_received; /* RFC4898 tcpEStatsAppHCThruOctetsReceived 163 * sum(delta(rcv_nxt)), or how many bytes 164 * were acked. 165 */ 166 u32 segs_in; /* RFC4898 tcpEStatsPerfSegsIn 167 * total number of segments in. 168 */ 169 u32 data_segs_in; /* RFC4898 tcpEStatsPerfDataSegsIn 170 * total number of data segments in. 171 */ 172 u32 rcv_nxt; /* What we want to receive next */ 173 u32 copied_seq; /* Head of yet unread data */ 174 u32 rcv_wup; /* rcv_nxt on last window update sent */ 175 u32 snd_nxt; /* Next sequence we send */ 176 u32 segs_out; /* RFC4898 tcpEStatsPerfSegsOut 177 * The total number of segments sent. 178 */ 179 u32 data_segs_out; /* RFC4898 tcpEStatsPerfDataSegsOut 180 * total number of data segments sent. 181 */ 182 u64 bytes_sent; /* RFC4898 tcpEStatsPerfHCDataOctetsOut 183 * total number of data bytes sent. 184 */ 185 u64 bytes_acked; /* RFC4898 tcpEStatsAppHCThruOctetsAcked 186 * sum(delta(snd_una)), or how many bytes 187 * were acked. 188 */ 189 u32 dsack_dups; /* RFC4898 tcpEStatsStackDSACKDups 190 * total number of DSACK blocks received 191 */ 192 u32 snd_una; /* First byte we want an ack for */ 193 u32 snd_sml; /* Last byte of the most recently transmitted small packet */ 194 u32 rcv_tstamp; /* timestamp of last received ACK (for keepalives) */ 195 u32 lsndtime; /* timestamp of last sent data packet (for restart window) */ 196 u32 last_oow_ack_time; /* timestamp of last out-of-window ACK */ 197 u32 compressed_ack_rcv_nxt; 198 199 u32 tsoffset; /* timestamp offset */ 200 201 struct list_head tsq_node; /* anchor in tsq_tasklet.head list */ 202 struct list_head tsorted_sent_queue; /* time-sorted sent but un-SACKed skbs */ 203 204 u32 snd_wl1; /* Sequence for window update */ 205 u32 snd_wnd; /* The window we expect to receive */ 206 u32 max_window; /* Maximal window ever seen from peer */ 207 u32 mss_cache; /* Cached effective mss, not including SACKS */ 208 209 u32 window_clamp; /* Maximal window to advertise */ 210 u32 rcv_ssthresh; /* Current window clamp */ 211 212 /* Information of the most recently (s)acked skb */ 213 struct tcp_rack { 214 u64 mstamp; /* (Re)sent time of the skb */ 215 u32 rtt_us; /* Associated RTT */ 216 u32 end_seq; /* Ending TCP sequence of the skb */ 217 u32 last_delivered; /* tp->delivered at last reo_wnd adj */ 218 u8 reo_wnd_steps; /* Allowed reordering window */ 219 #define TCP_RACK_RECOVERY_THRESH 16 220 u8 reo_wnd_persist:5, /* No. of recovery since last adj */ 221 dsack_seen:1, /* Whether DSACK seen after last adj */ 222 advanced:1; /* mstamp advanced since last lost marking */ 223 } rack; 224 u16 advmss; /* Advertised MSS */ 225 u8 compressed_ack; 226 u8 dup_ack_counter:2, 227 tlp_retrans:1, /* TLP is a retransmission */ 228 unused:5; 229 u32 chrono_start; /* Start time in jiffies of a TCP chrono */ 230 u32 chrono_stat[3]; /* Time in jiffies for chrono_stat stats */ 231 u8 chrono_type:2, /* current chronograph type */ 232 rate_app_limited:1, /* rate_{delivered,interval_us} limited? */ 233 fastopen_connect:1, /* FASTOPEN_CONNECT sockopt */ 234 fastopen_no_cookie:1, /* Allow send/recv SYN+data without a cookie */ 235 is_sack_reneg:1, /* in recovery from loss with SACK reneg? */ 236 fastopen_client_fail:2; /* reason why fastopen failed */ 237 u8 nonagle : 4,/* Disable Nagle algorithm? */ 238 thin_lto : 1,/* Use linear timeouts for thin streams */ 239 recvmsg_inq : 1,/* Indicate # of bytes in queue upon recvmsg */ 240 repair : 1, 241 frto : 1;/* F-RTO (RFC5682) activated in CA_Loss */ 242 u8 repair_queue; 243 u8 save_syn:2, /* Save headers of SYN packet */ 244 syn_data:1, /* SYN includes data */ 245 syn_fastopen:1, /* SYN includes Fast Open option */ 246 syn_fastopen_exp:1,/* SYN includes Fast Open exp. option */ 247 syn_fastopen_ch:1, /* Active TFO re-enabling probe */ 248 syn_data_acked:1,/* data in SYN is acked by SYN-ACK */ 249 is_cwnd_limited:1;/* forward progress limited by snd_cwnd? */ 250 u32 tlp_high_seq; /* snd_nxt at the time of TLP */ 251 252 u32 tcp_tx_delay; /* delay (in usec) added to TX packets */ 253 u64 tcp_wstamp_ns; /* departure time for next sent data packet */ 254 u64 tcp_clock_cache; /* cache last tcp_clock_ns() (see tcp_mstamp_refresh()) */ 255 256 /* RTT measurement */ 257 u64 tcp_mstamp; /* most recent packet received/sent */ 258 u32 srtt_us; /* smoothed round trip time << 3 in usecs */ 259 u32 mdev_us; /* medium deviation */ 260 u32 mdev_max_us; /* maximal mdev for the last rtt period */ 261 u32 rttvar_us; /* smoothed mdev_max */ 262 u32 rtt_seq; /* sequence number to update rttvar */ 263 struct minmax rtt_min; 264 265 u32 packets_out; /* Packets which are "in flight" */ 266 u32 retrans_out; /* Retransmitted packets out */ 267 u32 max_packets_out; /* max packets_out in last window */ 268 u32 max_packets_seq; /* right edge of max_packets_out flight */ 269 270 u16 urg_data; /* Saved octet of OOB data and control flags */ 271 u8 ecn_flags; /* ECN status bits. */ 272 u8 keepalive_probes; /* num of allowed keep alive probes */ 273 u32 reordering; /* Packet reordering metric. */ 274 u32 reord_seen; /* number of data packet reordering events */ 275 u32 snd_up; /* Urgent pointer */ 276 277 /* 278 * Options received (usually on last packet, some only on SYN packets). 279 */ 280 struct tcp_options_received rx_opt; 281 282 /* 283 * Slow start and congestion control (see also Nagle, and Karn & Partridge) 284 */ 285 u32 snd_ssthresh; /* Slow start size threshold */ 286 u32 snd_cwnd; /* Sending congestion window */ 287 u32 snd_cwnd_cnt; /* Linear increase counter */ 288 u32 snd_cwnd_clamp; /* Do not allow snd_cwnd to grow above this */ 289 u32 snd_cwnd_used; 290 u32 snd_cwnd_stamp; 291 u32 prior_cwnd; /* cwnd right before starting loss recovery */ 292 u32 prr_delivered; /* Number of newly delivered packets to 293 * receiver in Recovery. */ 294 u32 prr_out; /* Total number of pkts sent during Recovery. */ 295 u32 delivered; /* Total data packets delivered incl. rexmits */ 296 u32 delivered_ce; /* Like the above but only ECE marked packets */ 297 u32 lost; /* Total data packets lost incl. rexmits */ 298 u32 app_limited; /* limited until "delivered" reaches this val */ 299 u64 first_tx_mstamp; /* start of window send phase */ 300 u64 delivered_mstamp; /* time we reached "delivered" */ 301 u32 rate_delivered; /* saved rate sample: packets delivered */ 302 u32 rate_interval_us; /* saved rate sample: time elapsed */ 303 304 u32 rcv_wnd; /* Current receiver window */ 305 u32 write_seq; /* Tail(+1) of data held in tcp send buffer */ 306 u32 notsent_lowat; /* TCP_NOTSENT_LOWAT */ 307 u32 pushed_seq; /* Last pushed seq, required to talk to windows */ 308 u32 lost_out; /* Lost packets */ 309 u32 sacked_out; /* SACK'd packets */ 310 311 struct hrtimer pacing_timer; 312 struct hrtimer compressed_ack_timer; 313 314 /* from STCP, retrans queue hinting */ 315 struct sk_buff* lost_skb_hint; 316 struct sk_buff *retransmit_skb_hint; 317 318 /* OOO segments go in this rbtree. Socket lock must be held. */ 319 struct rb_root out_of_order_queue; 320 struct sk_buff *ooo_last_skb; /* cache rb_last(out_of_order_queue) */ 321 322 /* SACKs data, these 2 need to be together (see tcp_options_write) */ 323 struct tcp_sack_block duplicate_sack[1]; /* D-SACK block */ 324 struct tcp_sack_block selective_acks[4]; /* The SACKS themselves*/ 325 326 struct tcp_sack_block recv_sack_cache[4]; 327 328 struct sk_buff *highest_sack; /* skb just after the highest 329 * skb with SACKed bit set 330 * (validity guaranteed only if 331 * sacked_out > 0) 332 */ 333 334 int lost_cnt_hint; 335 336 u32 prior_ssthresh; /* ssthresh saved at recovery start */ 337 u32 high_seq; /* snd_nxt at onset of congestion */ 338 339 u32 retrans_stamp; /* Timestamp of the last retransmit, 340 * also used in SYN-SENT to remember stamp of 341 * the first SYN. */ 342 u32 undo_marker; /* snd_una upon a new recovery episode. */ 343 int undo_retrans; /* number of undoable retransmissions. */ 344 u64 bytes_retrans; /* RFC4898 tcpEStatsPerfOctetsRetrans 345 * Total data bytes retransmitted 346 */ 347 u32 total_retrans; /* Total retransmits for entire connection */ 348 349 u32 urg_seq; /* Seq of received urgent pointer */ 350 unsigned int keepalive_time; /* time before keep alive takes place */ 351 unsigned int keepalive_intvl; /* time interval between keep alive probes */ 352 353 int linger2; 354 355 356 /* Sock_ops bpf program related variables */ 357 #ifdef CONFIG_BPF 358 u8 bpf_sock_ops_cb_flags; /* Control calling BPF programs 359 * values defined in uapi/linux/tcp.h 360 */ 361 #define BPF_SOCK_OPS_TEST_FLAG(TP, ARG) (TP->bpf_sock_ops_cb_flags & ARG) 362 #else 363 #define BPF_SOCK_OPS_TEST_FLAG(TP, ARG) 0 364 #endif 365 366 u16 timeout_rehash; /* Timeout-triggered rehash attempts */ 367 368 u32 rcv_ooopack; /* Received out-of-order packets, for tcpinfo */ 369 370 /* Receiver side RTT estimation */ 371 u32 rcv_rtt_last_tsecr; 372 struct { 373 u32 rtt_us; 374 u32 seq; 375 u64 time; 376 } rcv_rtt_est; 377 378 /* Receiver queue space */ 379 struct { 380 u32 space; 381 u32 seq; 382 u64 time; 383 } rcvq_space; 384 385 /* TCP-specific MTU probe information. */ 386 struct { 387 u32 probe_seq_start; 388 u32 probe_seq_end; 389 } mtu_probe; 390 u32 mtu_info; /* We received an ICMP_FRAG_NEEDED / ICMPV6_PKT_TOOBIG 391 * while socket was owned by user. 392 */ 393 #if IS_ENABLED(CONFIG_MPTCP) 394 bool is_mptcp; 395 #endif 396 #if IS_ENABLED(CONFIG_SMC) 397 bool syn_smc; /* SYN includes SMC */ 398 #endif 399 400 #ifdef CONFIG_TCP_MD5SIG 401 /* TCP AF-Specific parts; only used by MD5 Signature support so far */ 402 const struct tcp_sock_af_ops *af_specific; 403 404 /* TCP MD5 Signature Option information */ 405 struct tcp_md5sig_info __rcu *md5sig_info; 406 #endif 407 408 /* TCP fastopen related information */ 409 struct tcp_fastopen_request *fastopen_req; 410 /* fastopen_rsk points to request_sock that resulted in this big 411 * socket. Used to retransmit SYNACKs etc. 412 */ 413 struct request_sock __rcu *fastopen_rsk; 414 struct saved_syn *saved_syn; 415 }; 416 417 enum tsq_enum { 418 TSQ_THROTTLED, 419 TSQ_QUEUED, 420 TCP_TSQ_DEFERRED, /* tcp_tasklet_func() found socket was owned */ 421 TCP_WRITE_TIMER_DEFERRED, /* tcp_write_timer() found socket was owned */ 422 TCP_DELACK_TIMER_DEFERRED, /* tcp_delack_timer() found socket was owned */ 423 TCP_MTU_REDUCED_DEFERRED, /* tcp_v{4|6}_err() could not call 424 * tcp_v{4|6}_mtu_reduced() 425 */ 426 }; 427 428 enum tsq_flags { 429 TSQF_THROTTLED = (1UL << TSQ_THROTTLED), 430 TSQF_QUEUED = (1UL << TSQ_QUEUED), 431 TCPF_TSQ_DEFERRED = (1UL << TCP_TSQ_DEFERRED), 432 TCPF_WRITE_TIMER_DEFERRED = (1UL << TCP_WRITE_TIMER_DEFERRED), 433 TCPF_DELACK_TIMER_DEFERRED = (1UL << TCP_DELACK_TIMER_DEFERRED), 434 TCPF_MTU_REDUCED_DEFERRED = (1UL << TCP_MTU_REDUCED_DEFERRED), 435 }; 436 437 static inline struct tcp_sock *tcp_sk(const struct sock *sk) 438 { 439 return (struct tcp_sock *)sk; 440 } 441 442 struct tcp_timewait_sock { 443 struct inet_timewait_sock tw_sk; 444 #define tw_rcv_nxt tw_sk.__tw_common.skc_tw_rcv_nxt 445 #define tw_snd_nxt tw_sk.__tw_common.skc_tw_snd_nxt 446 u32 tw_rcv_wnd; 447 u32 tw_ts_offset; 448 u32 tw_ts_recent; 449 450 /* The time we sent the last out-of-window ACK: */ 451 u32 tw_last_oow_ack_time; 452 453 int tw_ts_recent_stamp; 454 u32 tw_tx_delay; 455 #ifdef CONFIG_TCP_MD5SIG 456 struct tcp_md5sig_key *tw_md5_key; 457 #endif 458 }; 459 460 static inline struct tcp_timewait_sock *tcp_twsk(const struct sock *sk) 461 { 462 return (struct tcp_timewait_sock *)sk; 463 } 464 465 static inline bool tcp_passive_fastopen(const struct sock *sk) 466 { 467 return sk->sk_state == TCP_SYN_RECV && 468 rcu_access_pointer(tcp_sk(sk)->fastopen_rsk) != NULL; 469 } 470 471 static inline void fastopen_queue_tune(struct sock *sk, int backlog) 472 { 473 struct request_sock_queue *queue = &inet_csk(sk)->icsk_accept_queue; 474 int somaxconn = READ_ONCE(sock_net(sk)->core.sysctl_somaxconn); 475 476 queue->fastopenq.max_qlen = min_t(unsigned int, backlog, somaxconn); 477 } 478 479 static inline void tcp_move_syn(struct tcp_sock *tp, 480 struct request_sock *req) 481 { 482 tp->saved_syn = req->saved_syn; 483 req->saved_syn = NULL; 484 } 485 486 static inline void tcp_saved_syn_free(struct tcp_sock *tp) 487 { 488 kfree(tp->saved_syn); 489 tp->saved_syn = NULL; 490 } 491 492 static inline u32 tcp_saved_syn_len(const struct saved_syn *saved_syn) 493 { 494 return saved_syn->mac_hdrlen + saved_syn->network_hdrlen + 495 saved_syn->tcp_hdrlen; 496 } 497 498 struct sk_buff *tcp_get_timestamping_opt_stats(const struct sock *sk, 499 const struct sk_buff *orig_skb, 500 const struct sk_buff *ack_skb); 501 502 static inline u16 tcp_mss_clamp(const struct tcp_sock *tp, u16 mss) 503 { 504 /* We use READ_ONCE() here because socket might not be locked. 505 * This happens for listeners. 506 */ 507 u16 user_mss = READ_ONCE(tp->rx_opt.user_mss); 508 509 return (user_mss && user_mss < mss) ? user_mss : mss; 510 } 511 512 int tcp_skb_shift(struct sk_buff *to, struct sk_buff *from, int pcount, 513 int shiftlen); 514 515 void tcp_sock_set_cork(struct sock *sk, bool on); 516 int tcp_sock_set_keepcnt(struct sock *sk, int val); 517 int tcp_sock_set_keepidle_locked(struct sock *sk, int val); 518 int tcp_sock_set_keepidle(struct sock *sk, int val); 519 int tcp_sock_set_keepintvl(struct sock *sk, int val); 520 void tcp_sock_set_nodelay(struct sock *sk); 521 void tcp_sock_set_quickack(struct sock *sk, int val); 522 int tcp_sock_set_syncnt(struct sock *sk, int val); 523 void tcp_sock_set_user_timeout(struct sock *sk, u32 val); 524 525 #endif /* _LINUX_TCP_H */ 526