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, <[email protected]> 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 #if IS_ENABLED(CONFIG_MPTCP) 82 struct mptcp_options_received { 83 u64 sndr_key; 84 u64 rcvr_key; 85 u64 data_ack; 86 u64 data_seq; 87 u32 subflow_seq; 88 u16 data_len; 89 u8 mp_capable : 1, 90 mp_join : 1, 91 dss : 1; 92 u8 use_map:1, 93 dsn64:1, 94 data_fin:1, 95 use_ack:1, 96 ack64:1, 97 mpc_map:1, 98 __unused:2; 99 }; 100 #endif 101 102 struct tcp_options_received { 103 /* PAWS/RTTM data */ 104 int ts_recent_stamp;/* Time we stored ts_recent (for aging) */ 105 u32 ts_recent; /* Time stamp to echo next */ 106 u32 rcv_tsval; /* Time stamp value */ 107 u32 rcv_tsecr; /* Time stamp echo reply */ 108 u16 saw_tstamp : 1, /* Saw TIMESTAMP on last packet */ 109 tstamp_ok : 1, /* TIMESTAMP seen on SYN packet */ 110 dsack : 1, /* D-SACK is scheduled */ 111 wscale_ok : 1, /* Wscale seen on SYN packet */ 112 sack_ok : 3, /* SACK seen on SYN packet */ 113 smc_ok : 1, /* SMC seen on SYN packet */ 114 snd_wscale : 4, /* Window scaling received from sender */ 115 rcv_wscale : 4; /* Window scaling to send to receiver */ 116 u8 num_sacks; /* Number of SACK blocks */ 117 u16 user_mss; /* mss requested by user in ioctl */ 118 u16 mss_clamp; /* Maximal mss, negotiated at connection setup */ 119 #if IS_ENABLED(CONFIG_MPTCP) 120 struct mptcp_options_received mptcp; 121 #endif 122 }; 123 124 static inline void tcp_clear_options(struct tcp_options_received *rx_opt) 125 { 126 rx_opt->tstamp_ok = rx_opt->sack_ok = 0; 127 rx_opt->wscale_ok = rx_opt->snd_wscale = 0; 128 #if IS_ENABLED(CONFIG_SMC) 129 rx_opt->smc_ok = 0; 130 #endif 131 #if IS_ENABLED(CONFIG_MPTCP) 132 rx_opt->mptcp.mp_capable = 0; 133 rx_opt->mptcp.mp_join = 0; 134 rx_opt->mptcp.dss = 0; 135 #endif 136 } 137 138 /* This is the max number of SACKS that we'll generate and process. It's safe 139 * to increase this, although since: 140 * size = TCPOLEN_SACK_BASE_ALIGNED (4) + n * TCPOLEN_SACK_PERBLOCK (8) 141 * only four options will fit in a standard TCP header */ 142 #define TCP_NUM_SACKS 4 143 144 struct tcp_request_sock_ops; 145 146 struct tcp_request_sock { 147 struct inet_request_sock req; 148 const struct tcp_request_sock_ops *af_specific; 149 u64 snt_synack; /* first SYNACK sent time */ 150 bool tfo_listener; 151 #if IS_ENABLED(CONFIG_MPTCP) 152 bool is_mptcp; 153 #endif 154 u32 txhash; 155 u32 rcv_isn; 156 u32 snt_isn; 157 u32 ts_off; 158 u32 last_oow_ack_time; /* last SYNACK */ 159 u32 rcv_nxt; /* the ack # by SYNACK. For 160 * FastOpen it's the seq# 161 * after data-in-SYN. 162 */ 163 }; 164 165 static inline struct tcp_request_sock *tcp_rsk(const struct request_sock *req) 166 { 167 return (struct tcp_request_sock *)req; 168 } 169 170 struct tcp_sock { 171 /* inet_connection_sock has to be the first member of tcp_sock */ 172 struct inet_connection_sock inet_conn; 173 u16 tcp_header_len; /* Bytes of tcp header to send */ 174 u16 gso_segs; /* Max number of segs per GSO packet */ 175 176 /* 177 * Header prediction flags 178 * 0x5?10 << 16 + snd_wnd in net byte order 179 */ 180 __be32 pred_flags; 181 182 /* 183 * RFC793 variables by their proper names. This means you can 184 * read the code and the spec side by side (and laugh ...) 185 * See RFC793 and RFC1122. The RFC writes these in capitals. 186 */ 187 u64 bytes_received; /* RFC4898 tcpEStatsAppHCThruOctetsReceived 188 * sum(delta(rcv_nxt)), or how many bytes 189 * were acked. 190 */ 191 u32 segs_in; /* RFC4898 tcpEStatsPerfSegsIn 192 * total number of segments in. 193 */ 194 u32 data_segs_in; /* RFC4898 tcpEStatsPerfDataSegsIn 195 * total number of data segments in. 196 */ 197 u32 rcv_nxt; /* What we want to receive next */ 198 u32 copied_seq; /* Head of yet unread data */ 199 u32 rcv_wup; /* rcv_nxt on last window update sent */ 200 u32 snd_nxt; /* Next sequence we send */ 201 u32 segs_out; /* RFC4898 tcpEStatsPerfSegsOut 202 * The total number of segments sent. 203 */ 204 u32 data_segs_out; /* RFC4898 tcpEStatsPerfDataSegsOut 205 * total number of data segments sent. 206 */ 207 u64 bytes_sent; /* RFC4898 tcpEStatsPerfHCDataOctetsOut 208 * total number of data bytes sent. 209 */ 210 u64 bytes_acked; /* RFC4898 tcpEStatsAppHCThruOctetsAcked 211 * sum(delta(snd_una)), or how many bytes 212 * were acked. 213 */ 214 u32 dsack_dups; /* RFC4898 tcpEStatsStackDSACKDups 215 * total number of DSACK blocks received 216 */ 217 u32 snd_una; /* First byte we want an ack for */ 218 u32 snd_sml; /* Last byte of the most recently transmitted small packet */ 219 u32 rcv_tstamp; /* timestamp of last received ACK (for keepalives) */ 220 u32 lsndtime; /* timestamp of last sent data packet (for restart window) */ 221 u32 last_oow_ack_time; /* timestamp of last out-of-window ACK */ 222 u32 compressed_ack_rcv_nxt; 223 224 u32 tsoffset; /* timestamp offset */ 225 226 struct list_head tsq_node; /* anchor in tsq_tasklet.head list */ 227 struct list_head tsorted_sent_queue; /* time-sorted sent but un-SACKed skbs */ 228 229 u32 snd_wl1; /* Sequence for window update */ 230 u32 snd_wnd; /* The window we expect to receive */ 231 u32 max_window; /* Maximal window ever seen from peer */ 232 u32 mss_cache; /* Cached effective mss, not including SACKS */ 233 234 u32 window_clamp; /* Maximal window to advertise */ 235 u32 rcv_ssthresh; /* Current window clamp */ 236 237 /* Information of the most recently (s)acked skb */ 238 struct tcp_rack { 239 u64 mstamp; /* (Re)sent time of the skb */ 240 u32 rtt_us; /* Associated RTT */ 241 u32 end_seq; /* Ending TCP sequence of the skb */ 242 u32 last_delivered; /* tp->delivered at last reo_wnd adj */ 243 u8 reo_wnd_steps; /* Allowed reordering window */ 244 #define TCP_RACK_RECOVERY_THRESH 16 245 u8 reo_wnd_persist:5, /* No. of recovery since last adj */ 246 dsack_seen:1, /* Whether DSACK seen after last adj */ 247 advanced:1; /* mstamp advanced since last lost marking */ 248 } rack; 249 u16 advmss; /* Advertised MSS */ 250 u8 compressed_ack; 251 u32 chrono_start; /* Start time in jiffies of a TCP chrono */ 252 u32 chrono_stat[3]; /* Time in jiffies for chrono_stat stats */ 253 u8 chrono_type:2, /* current chronograph type */ 254 rate_app_limited:1, /* rate_{delivered,interval_us} limited? */ 255 fastopen_connect:1, /* FASTOPEN_CONNECT sockopt */ 256 fastopen_no_cookie:1, /* Allow send/recv SYN+data without a cookie */ 257 is_sack_reneg:1, /* in recovery from loss with SACK reneg? */ 258 fastopen_client_fail:2; /* reason why fastopen failed */ 259 u8 nonagle : 4,/* Disable Nagle algorithm? */ 260 thin_lto : 1,/* Use linear timeouts for thin streams */ 261 recvmsg_inq : 1,/* Indicate # of bytes in queue upon recvmsg */ 262 repair : 1, 263 frto : 1;/* F-RTO (RFC5682) activated in CA_Loss */ 264 u8 repair_queue; 265 u8 syn_data:1, /* SYN includes data */ 266 syn_fastopen:1, /* SYN includes Fast Open option */ 267 syn_fastopen_exp:1,/* SYN includes Fast Open exp. option */ 268 syn_fastopen_ch:1, /* Active TFO re-enabling probe */ 269 syn_data_acked:1,/* data in SYN is acked by SYN-ACK */ 270 save_syn:1, /* Save headers of SYN packet */ 271 is_cwnd_limited:1,/* forward progress limited by snd_cwnd? */ 272 syn_smc:1; /* SYN includes SMC */ 273 u32 tlp_high_seq; /* snd_nxt at the time of TLP retransmit. */ 274 275 u32 tcp_tx_delay; /* delay (in usec) added to TX packets */ 276 u64 tcp_wstamp_ns; /* departure time for next sent data packet */ 277 u64 tcp_clock_cache; /* cache last tcp_clock_ns() (see tcp_mstamp_refresh()) */ 278 279 /* RTT measurement */ 280 u64 tcp_mstamp; /* most recent packet received/sent */ 281 u32 srtt_us; /* smoothed round trip time << 3 in usecs */ 282 u32 mdev_us; /* medium deviation */ 283 u32 mdev_max_us; /* maximal mdev for the last rtt period */ 284 u32 rttvar_us; /* smoothed mdev_max */ 285 u32 rtt_seq; /* sequence number to update rttvar */ 286 struct minmax rtt_min; 287 288 u32 packets_out; /* Packets which are "in flight" */ 289 u32 retrans_out; /* Retransmitted packets out */ 290 u32 max_packets_out; /* max packets_out in last window */ 291 u32 max_packets_seq; /* right edge of max_packets_out flight */ 292 293 u16 urg_data; /* Saved octet of OOB data and control flags */ 294 u8 ecn_flags; /* ECN status bits. */ 295 u8 keepalive_probes; /* num of allowed keep alive probes */ 296 u32 reordering; /* Packet reordering metric. */ 297 u32 reord_seen; /* number of data packet reordering events */ 298 u32 snd_up; /* Urgent pointer */ 299 300 /* 301 * Options received (usually on last packet, some only on SYN packets). 302 */ 303 struct tcp_options_received rx_opt; 304 305 /* 306 * Slow start and congestion control (see also Nagle, and Karn & Partridge) 307 */ 308 u32 snd_ssthresh; /* Slow start size threshold */ 309 u32 snd_cwnd; /* Sending congestion window */ 310 u32 snd_cwnd_cnt; /* Linear increase counter */ 311 u32 snd_cwnd_clamp; /* Do not allow snd_cwnd to grow above this */ 312 u32 snd_cwnd_used; 313 u32 snd_cwnd_stamp; 314 u32 prior_cwnd; /* cwnd right before starting loss recovery */ 315 u32 prr_delivered; /* Number of newly delivered packets to 316 * receiver in Recovery. */ 317 u32 prr_out; /* Total number of pkts sent during Recovery. */ 318 u32 delivered; /* Total data packets delivered incl. rexmits */ 319 u32 delivered_ce; /* Like the above but only ECE marked packets */ 320 u32 lost; /* Total data packets lost incl. rexmits */ 321 u32 app_limited; /* limited until "delivered" reaches this val */ 322 u64 first_tx_mstamp; /* start of window send phase */ 323 u64 delivered_mstamp; /* time we reached "delivered" */ 324 u32 rate_delivered; /* saved rate sample: packets delivered */ 325 u32 rate_interval_us; /* saved rate sample: time elapsed */ 326 327 u32 rcv_wnd; /* Current receiver window */ 328 u32 write_seq; /* Tail(+1) of data held in tcp send buffer */ 329 u32 notsent_lowat; /* TCP_NOTSENT_LOWAT */ 330 u32 pushed_seq; /* Last pushed seq, required to talk to windows */ 331 u32 lost_out; /* Lost packets */ 332 u32 sacked_out; /* SACK'd packets */ 333 334 struct hrtimer pacing_timer; 335 struct hrtimer compressed_ack_timer; 336 337 /* from STCP, retrans queue hinting */ 338 struct sk_buff* lost_skb_hint; 339 struct sk_buff *retransmit_skb_hint; 340 341 /* OOO segments go in this rbtree. Socket lock must be held. */ 342 struct rb_root out_of_order_queue; 343 struct sk_buff *ooo_last_skb; /* cache rb_last(out_of_order_queue) */ 344 345 /* SACKs data, these 2 need to be together (see tcp_options_write) */ 346 struct tcp_sack_block duplicate_sack[1]; /* D-SACK block */ 347 struct tcp_sack_block selective_acks[4]; /* The SACKS themselves*/ 348 349 struct tcp_sack_block recv_sack_cache[4]; 350 351 struct sk_buff *highest_sack; /* skb just after the highest 352 * skb with SACKed bit set 353 * (validity guaranteed only if 354 * sacked_out > 0) 355 */ 356 357 int lost_cnt_hint; 358 359 u32 prior_ssthresh; /* ssthresh saved at recovery start */ 360 u32 high_seq; /* snd_nxt at onset of congestion */ 361 362 u32 retrans_stamp; /* Timestamp of the last retransmit, 363 * also used in SYN-SENT to remember stamp of 364 * the first SYN. */ 365 u32 undo_marker; /* snd_una upon a new recovery episode. */ 366 int undo_retrans; /* number of undoable retransmissions. */ 367 u64 bytes_retrans; /* RFC4898 tcpEStatsPerfOctetsRetrans 368 * Total data bytes retransmitted 369 */ 370 u32 total_retrans; /* Total retransmits for entire connection */ 371 372 u32 urg_seq; /* Seq of received urgent pointer */ 373 unsigned int keepalive_time; /* time before keep alive takes place */ 374 unsigned int keepalive_intvl; /* time interval between keep alive probes */ 375 376 int linger2; 377 378 379 /* Sock_ops bpf program related variables */ 380 #ifdef CONFIG_BPF 381 u8 bpf_sock_ops_cb_flags; /* Control calling BPF programs 382 * values defined in uapi/linux/tcp.h 383 */ 384 #define BPF_SOCK_OPS_TEST_FLAG(TP, ARG) (TP->bpf_sock_ops_cb_flags & ARG) 385 #else 386 #define BPF_SOCK_OPS_TEST_FLAG(TP, ARG) 0 387 #endif 388 389 u16 timeout_rehash; /* Timeout-triggered rehash attempts */ 390 391 u32 rcv_ooopack; /* Received out-of-order packets, for tcpinfo */ 392 393 /* Receiver side RTT estimation */ 394 u32 rcv_rtt_last_tsecr; 395 struct { 396 u32 rtt_us; 397 u32 seq; 398 u64 time; 399 } rcv_rtt_est; 400 401 /* Receiver queue space */ 402 struct { 403 u32 space; 404 u32 seq; 405 u64 time; 406 } rcvq_space; 407 408 /* TCP-specific MTU probe information. */ 409 struct { 410 u32 probe_seq_start; 411 u32 probe_seq_end; 412 } mtu_probe; 413 u32 mtu_info; /* We received an ICMP_FRAG_NEEDED / ICMPV6_PKT_TOOBIG 414 * while socket was owned by user. 415 */ 416 #if IS_ENABLED(CONFIG_MPTCP) 417 bool is_mptcp; 418 #endif 419 420 #ifdef CONFIG_TCP_MD5SIG 421 /* TCP AF-Specific parts; only used by MD5 Signature support so far */ 422 const struct tcp_sock_af_ops *af_specific; 423 424 /* TCP MD5 Signature Option information */ 425 struct tcp_md5sig_info __rcu *md5sig_info; 426 #endif 427 428 /* TCP fastopen related information */ 429 struct tcp_fastopen_request *fastopen_req; 430 /* fastopen_rsk points to request_sock that resulted in this big 431 * socket. Used to retransmit SYNACKs etc. 432 */ 433 struct request_sock __rcu *fastopen_rsk; 434 u32 *saved_syn; 435 }; 436 437 enum tsq_enum { 438 TSQ_THROTTLED, 439 TSQ_QUEUED, 440 TCP_TSQ_DEFERRED, /* tcp_tasklet_func() found socket was owned */ 441 TCP_WRITE_TIMER_DEFERRED, /* tcp_write_timer() found socket was owned */ 442 TCP_DELACK_TIMER_DEFERRED, /* tcp_delack_timer() found socket was owned */ 443 TCP_MTU_REDUCED_DEFERRED, /* tcp_v{4|6}_err() could not call 444 * tcp_v{4|6}_mtu_reduced() 445 */ 446 }; 447 448 enum tsq_flags { 449 TSQF_THROTTLED = (1UL << TSQ_THROTTLED), 450 TSQF_QUEUED = (1UL << TSQ_QUEUED), 451 TCPF_TSQ_DEFERRED = (1UL << TCP_TSQ_DEFERRED), 452 TCPF_WRITE_TIMER_DEFERRED = (1UL << TCP_WRITE_TIMER_DEFERRED), 453 TCPF_DELACK_TIMER_DEFERRED = (1UL << TCP_DELACK_TIMER_DEFERRED), 454 TCPF_MTU_REDUCED_DEFERRED = (1UL << TCP_MTU_REDUCED_DEFERRED), 455 }; 456 457 static inline struct tcp_sock *tcp_sk(const struct sock *sk) 458 { 459 return (struct tcp_sock *)sk; 460 } 461 462 struct tcp_timewait_sock { 463 struct inet_timewait_sock tw_sk; 464 #define tw_rcv_nxt tw_sk.__tw_common.skc_tw_rcv_nxt 465 #define tw_snd_nxt tw_sk.__tw_common.skc_tw_snd_nxt 466 u32 tw_rcv_wnd; 467 u32 tw_ts_offset; 468 u32 tw_ts_recent; 469 470 /* The time we sent the last out-of-window ACK: */ 471 u32 tw_last_oow_ack_time; 472 473 int tw_ts_recent_stamp; 474 u32 tw_tx_delay; 475 #ifdef CONFIG_TCP_MD5SIG 476 struct tcp_md5sig_key *tw_md5_key; 477 #endif 478 }; 479 480 static inline struct tcp_timewait_sock *tcp_twsk(const struct sock *sk) 481 { 482 return (struct tcp_timewait_sock *)sk; 483 } 484 485 static inline bool tcp_passive_fastopen(const struct sock *sk) 486 { 487 return sk->sk_state == TCP_SYN_RECV && 488 rcu_access_pointer(tcp_sk(sk)->fastopen_rsk) != NULL; 489 } 490 491 static inline void fastopen_queue_tune(struct sock *sk, int backlog) 492 { 493 struct request_sock_queue *queue = &inet_csk(sk)->icsk_accept_queue; 494 int somaxconn = READ_ONCE(sock_net(sk)->core.sysctl_somaxconn); 495 496 queue->fastopenq.max_qlen = min_t(unsigned int, backlog, somaxconn); 497 } 498 499 static inline void tcp_move_syn(struct tcp_sock *tp, 500 struct request_sock *req) 501 { 502 tp->saved_syn = req->saved_syn; 503 req->saved_syn = NULL; 504 } 505 506 static inline void tcp_saved_syn_free(struct tcp_sock *tp) 507 { 508 kfree(tp->saved_syn); 509 tp->saved_syn = NULL; 510 } 511 512 struct sk_buff *tcp_get_timestamping_opt_stats(const struct sock *sk); 513 514 static inline u16 tcp_mss_clamp(const struct tcp_sock *tp, u16 mss) 515 { 516 /* We use READ_ONCE() here because socket might not be locked. 517 * This happens for listeners. 518 */ 519 u16 user_mss = READ_ONCE(tp->rx_opt.user_mss); 520 521 return (user_mss && user_mss < mss) ? user_mss : mss; 522 } 523 524 int tcp_skb_shift(struct sk_buff *to, struct sk_buff *from, int pcount, 525 int shiftlen); 526 527 #endif /* _LINUX_TCP_H */ 528