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 u16 mp_capable : 1, 90 mp_join : 1, 91 dss : 1, 92 add_addr : 1, 93 rm_addr : 1, 94 family : 4, 95 echo : 1, 96 backup : 1; 97 u32 token; 98 u32 nonce; 99 u64 thmac; 100 u8 hmac[20]; 101 u8 join_id; 102 u8 use_map:1, 103 dsn64:1, 104 data_fin:1, 105 use_ack:1, 106 ack64:1, 107 mpc_map:1, 108 __unused:2; 109 u8 addr_id; 110 u8 rm_id; 111 union { 112 struct in_addr addr; 113 #if IS_ENABLED(CONFIG_MPTCP_IPV6) 114 struct in6_addr addr6; 115 #endif 116 }; 117 u64 ahmac; 118 u16 port; 119 }; 120 #endif 121 122 struct tcp_options_received { 123 /* PAWS/RTTM data */ 124 int ts_recent_stamp;/* Time we stored ts_recent (for aging) */ 125 u32 ts_recent; /* Time stamp to echo next */ 126 u32 rcv_tsval; /* Time stamp value */ 127 u32 rcv_tsecr; /* Time stamp echo reply */ 128 u16 saw_tstamp : 1, /* Saw TIMESTAMP on last packet */ 129 tstamp_ok : 1, /* TIMESTAMP seen on SYN packet */ 130 dsack : 1, /* D-SACK is scheduled */ 131 wscale_ok : 1, /* Wscale seen on SYN packet */ 132 sack_ok : 3, /* SACK seen on SYN packet */ 133 smc_ok : 1, /* SMC seen on SYN packet */ 134 snd_wscale : 4, /* Window scaling received from sender */ 135 rcv_wscale : 4; /* Window scaling to send to receiver */ 136 u8 num_sacks; /* Number of SACK blocks */ 137 u16 user_mss; /* mss requested by user in ioctl */ 138 u16 mss_clamp; /* Maximal mss, negotiated at connection setup */ 139 #if IS_ENABLED(CONFIG_MPTCP) 140 struct mptcp_options_received mptcp; 141 #endif 142 }; 143 144 static inline void tcp_clear_options(struct tcp_options_received *rx_opt) 145 { 146 rx_opt->tstamp_ok = rx_opt->sack_ok = 0; 147 rx_opt->wscale_ok = rx_opt->snd_wscale = 0; 148 #if IS_ENABLED(CONFIG_SMC) 149 rx_opt->smc_ok = 0; 150 #endif 151 #if IS_ENABLED(CONFIG_MPTCP) 152 rx_opt->mptcp.mp_capable = 0; 153 rx_opt->mptcp.mp_join = 0; 154 rx_opt->mptcp.add_addr = 0; 155 rx_opt->mptcp.rm_addr = 0; 156 rx_opt->mptcp.dss = 0; 157 #endif 158 } 159 160 /* This is the max number of SACKS that we'll generate and process. It's safe 161 * to increase this, although since: 162 * size = TCPOLEN_SACK_BASE_ALIGNED (4) + n * TCPOLEN_SACK_PERBLOCK (8) 163 * only four options will fit in a standard TCP header */ 164 #define TCP_NUM_SACKS 4 165 166 struct tcp_request_sock_ops; 167 168 struct tcp_request_sock { 169 struct inet_request_sock req; 170 const struct tcp_request_sock_ops *af_specific; 171 u64 snt_synack; /* first SYNACK sent time */ 172 bool tfo_listener; 173 bool is_mptcp; 174 u32 txhash; 175 u32 rcv_isn; 176 u32 snt_isn; 177 u32 ts_off; 178 u32 last_oow_ack_time; /* last SYNACK */ 179 u32 rcv_nxt; /* the ack # by SYNACK. For 180 * FastOpen it's the seq# 181 * after data-in-SYN. 182 */ 183 }; 184 185 static inline struct tcp_request_sock *tcp_rsk(const struct request_sock *req) 186 { 187 return (struct tcp_request_sock *)req; 188 } 189 190 struct tcp_sock { 191 /* inet_connection_sock has to be the first member of tcp_sock */ 192 struct inet_connection_sock inet_conn; 193 u16 tcp_header_len; /* Bytes of tcp header to send */ 194 u16 gso_segs; /* Max number of segs per GSO packet */ 195 196 /* 197 * Header prediction flags 198 * 0x5?10 << 16 + snd_wnd in net byte order 199 */ 200 __be32 pred_flags; 201 202 /* 203 * RFC793 variables by their proper names. This means you can 204 * read the code and the spec side by side (and laugh ...) 205 * See RFC793 and RFC1122. The RFC writes these in capitals. 206 */ 207 u64 bytes_received; /* RFC4898 tcpEStatsAppHCThruOctetsReceived 208 * sum(delta(rcv_nxt)), or how many bytes 209 * were acked. 210 */ 211 u32 segs_in; /* RFC4898 tcpEStatsPerfSegsIn 212 * total number of segments in. 213 */ 214 u32 data_segs_in; /* RFC4898 tcpEStatsPerfDataSegsIn 215 * total number of data segments in. 216 */ 217 u32 rcv_nxt; /* What we want to receive next */ 218 u32 copied_seq; /* Head of yet unread data */ 219 u32 rcv_wup; /* rcv_nxt on last window update sent */ 220 u32 snd_nxt; /* Next sequence we send */ 221 u32 segs_out; /* RFC4898 tcpEStatsPerfSegsOut 222 * The total number of segments sent. 223 */ 224 u32 data_segs_out; /* RFC4898 tcpEStatsPerfDataSegsOut 225 * total number of data segments sent. 226 */ 227 u64 bytes_sent; /* RFC4898 tcpEStatsPerfHCDataOctetsOut 228 * total number of data bytes sent. 229 */ 230 u64 bytes_acked; /* RFC4898 tcpEStatsAppHCThruOctetsAcked 231 * sum(delta(snd_una)), or how many bytes 232 * were acked. 233 */ 234 u32 dsack_dups; /* RFC4898 tcpEStatsStackDSACKDups 235 * total number of DSACK blocks received 236 */ 237 u32 snd_una; /* First byte we want an ack for */ 238 u32 snd_sml; /* Last byte of the most recently transmitted small packet */ 239 u32 rcv_tstamp; /* timestamp of last received ACK (for keepalives) */ 240 u32 lsndtime; /* timestamp of last sent data packet (for restart window) */ 241 u32 last_oow_ack_time; /* timestamp of last out-of-window ACK */ 242 u32 compressed_ack_rcv_nxt; 243 244 u32 tsoffset; /* timestamp offset */ 245 246 struct list_head tsq_node; /* anchor in tsq_tasklet.head list */ 247 struct list_head tsorted_sent_queue; /* time-sorted sent but un-SACKed skbs */ 248 249 u32 snd_wl1; /* Sequence for window update */ 250 u32 snd_wnd; /* The window we expect to receive */ 251 u32 max_window; /* Maximal window ever seen from peer */ 252 u32 mss_cache; /* Cached effective mss, not including SACKS */ 253 254 u32 window_clamp; /* Maximal window to advertise */ 255 u32 rcv_ssthresh; /* Current window clamp */ 256 257 /* Information of the most recently (s)acked skb */ 258 struct tcp_rack { 259 u64 mstamp; /* (Re)sent time of the skb */ 260 u32 rtt_us; /* Associated RTT */ 261 u32 end_seq; /* Ending TCP sequence of the skb */ 262 u32 last_delivered; /* tp->delivered at last reo_wnd adj */ 263 u8 reo_wnd_steps; /* Allowed reordering window */ 264 #define TCP_RACK_RECOVERY_THRESH 16 265 u8 reo_wnd_persist:5, /* No. of recovery since last adj */ 266 dsack_seen:1, /* Whether DSACK seen after last adj */ 267 advanced:1; /* mstamp advanced since last lost marking */ 268 } rack; 269 u16 advmss; /* Advertised MSS */ 270 u8 compressed_ack; 271 u32 chrono_start; /* Start time in jiffies of a TCP chrono */ 272 u32 chrono_stat[3]; /* Time in jiffies for chrono_stat stats */ 273 u8 chrono_type:2, /* current chronograph type */ 274 rate_app_limited:1, /* rate_{delivered,interval_us} limited? */ 275 fastopen_connect:1, /* FASTOPEN_CONNECT sockopt */ 276 fastopen_no_cookie:1, /* Allow send/recv SYN+data without a cookie */ 277 is_sack_reneg:1, /* in recovery from loss with SACK reneg? */ 278 fastopen_client_fail:2; /* reason why fastopen failed */ 279 u8 nonagle : 4,/* Disable Nagle algorithm? */ 280 thin_lto : 1,/* Use linear timeouts for thin streams */ 281 recvmsg_inq : 1,/* Indicate # of bytes in queue upon recvmsg */ 282 repair : 1, 283 frto : 1;/* F-RTO (RFC5682) activated in CA_Loss */ 284 u8 repair_queue; 285 u8 syn_data:1, /* SYN includes data */ 286 syn_fastopen:1, /* SYN includes Fast Open option */ 287 syn_fastopen_exp:1,/* SYN includes Fast Open exp. option */ 288 syn_fastopen_ch:1, /* Active TFO re-enabling probe */ 289 syn_data_acked:1,/* data in SYN is acked by SYN-ACK */ 290 save_syn:1, /* Save headers of SYN packet */ 291 is_cwnd_limited:1,/* forward progress limited by snd_cwnd? */ 292 syn_smc:1; /* SYN includes SMC */ 293 u32 tlp_high_seq; /* snd_nxt at the time of TLP retransmit. */ 294 295 u32 tcp_tx_delay; /* delay (in usec) added to TX packets */ 296 u64 tcp_wstamp_ns; /* departure time for next sent data packet */ 297 u64 tcp_clock_cache; /* cache last tcp_clock_ns() (see tcp_mstamp_refresh()) */ 298 299 /* RTT measurement */ 300 u64 tcp_mstamp; /* most recent packet received/sent */ 301 u32 srtt_us; /* smoothed round trip time << 3 in usecs */ 302 u32 mdev_us; /* medium deviation */ 303 u32 mdev_max_us; /* maximal mdev for the last rtt period */ 304 u32 rttvar_us; /* smoothed mdev_max */ 305 u32 rtt_seq; /* sequence number to update rttvar */ 306 struct minmax rtt_min; 307 308 u32 packets_out; /* Packets which are "in flight" */ 309 u32 retrans_out; /* Retransmitted packets out */ 310 u32 max_packets_out; /* max packets_out in last window */ 311 u32 max_packets_seq; /* right edge of max_packets_out flight */ 312 313 u16 urg_data; /* Saved octet of OOB data and control flags */ 314 u8 ecn_flags; /* ECN status bits. */ 315 u8 keepalive_probes; /* num of allowed keep alive probes */ 316 u32 reordering; /* Packet reordering metric. */ 317 u32 reord_seen; /* number of data packet reordering events */ 318 u32 snd_up; /* Urgent pointer */ 319 320 /* 321 * Options received (usually on last packet, some only on SYN packets). 322 */ 323 struct tcp_options_received rx_opt; 324 325 /* 326 * Slow start and congestion control (see also Nagle, and Karn & Partridge) 327 */ 328 u32 snd_ssthresh; /* Slow start size threshold */ 329 u32 snd_cwnd; /* Sending congestion window */ 330 u32 snd_cwnd_cnt; /* Linear increase counter */ 331 u32 snd_cwnd_clamp; /* Do not allow snd_cwnd to grow above this */ 332 u32 snd_cwnd_used; 333 u32 snd_cwnd_stamp; 334 u32 prior_cwnd; /* cwnd right before starting loss recovery */ 335 u32 prr_delivered; /* Number of newly delivered packets to 336 * receiver in Recovery. */ 337 u32 prr_out; /* Total number of pkts sent during Recovery. */ 338 u32 delivered; /* Total data packets delivered incl. rexmits */ 339 u32 delivered_ce; /* Like the above but only ECE marked packets */ 340 u32 lost; /* Total data packets lost incl. rexmits */ 341 u32 app_limited; /* limited until "delivered" reaches this val */ 342 u64 first_tx_mstamp; /* start of window send phase */ 343 u64 delivered_mstamp; /* time we reached "delivered" */ 344 u32 rate_delivered; /* saved rate sample: packets delivered */ 345 u32 rate_interval_us; /* saved rate sample: time elapsed */ 346 347 u32 rcv_wnd; /* Current receiver window */ 348 u32 write_seq; /* Tail(+1) of data held in tcp send buffer */ 349 u32 notsent_lowat; /* TCP_NOTSENT_LOWAT */ 350 u32 pushed_seq; /* Last pushed seq, required to talk to windows */ 351 u32 lost_out; /* Lost packets */ 352 u32 sacked_out; /* SACK'd packets */ 353 354 struct hrtimer pacing_timer; 355 struct hrtimer compressed_ack_timer; 356 357 /* from STCP, retrans queue hinting */ 358 struct sk_buff* lost_skb_hint; 359 struct sk_buff *retransmit_skb_hint; 360 361 /* OOO segments go in this rbtree. Socket lock must be held. */ 362 struct rb_root out_of_order_queue; 363 struct sk_buff *ooo_last_skb; /* cache rb_last(out_of_order_queue) */ 364 365 /* SACKs data, these 2 need to be together (see tcp_options_write) */ 366 struct tcp_sack_block duplicate_sack[1]; /* D-SACK block */ 367 struct tcp_sack_block selective_acks[4]; /* The SACKS themselves*/ 368 369 struct tcp_sack_block recv_sack_cache[4]; 370 371 struct sk_buff *highest_sack; /* skb just after the highest 372 * skb with SACKed bit set 373 * (validity guaranteed only if 374 * sacked_out > 0) 375 */ 376 377 int lost_cnt_hint; 378 379 u32 prior_ssthresh; /* ssthresh saved at recovery start */ 380 u32 high_seq; /* snd_nxt at onset of congestion */ 381 382 u32 retrans_stamp; /* Timestamp of the last retransmit, 383 * also used in SYN-SENT to remember stamp of 384 * the first SYN. */ 385 u32 undo_marker; /* snd_una upon a new recovery episode. */ 386 int undo_retrans; /* number of undoable retransmissions. */ 387 u64 bytes_retrans; /* RFC4898 tcpEStatsPerfOctetsRetrans 388 * Total data bytes retransmitted 389 */ 390 u32 total_retrans; /* Total retransmits for entire connection */ 391 392 u32 urg_seq; /* Seq of received urgent pointer */ 393 unsigned int keepalive_time; /* time before keep alive takes place */ 394 unsigned int keepalive_intvl; /* time interval between keep alive probes */ 395 396 int linger2; 397 398 399 /* Sock_ops bpf program related variables */ 400 #ifdef CONFIG_BPF 401 u8 bpf_sock_ops_cb_flags; /* Control calling BPF programs 402 * values defined in uapi/linux/tcp.h 403 */ 404 #define BPF_SOCK_OPS_TEST_FLAG(TP, ARG) (TP->bpf_sock_ops_cb_flags & ARG) 405 #else 406 #define BPF_SOCK_OPS_TEST_FLAG(TP, ARG) 0 407 #endif 408 409 u16 timeout_rehash; /* Timeout-triggered rehash attempts */ 410 411 u32 rcv_ooopack; /* Received out-of-order packets, for tcpinfo */ 412 413 /* Receiver side RTT estimation */ 414 u32 rcv_rtt_last_tsecr; 415 struct { 416 u32 rtt_us; 417 u32 seq; 418 u64 time; 419 } rcv_rtt_est; 420 421 /* Receiver queue space */ 422 struct { 423 u32 space; 424 u32 seq; 425 u64 time; 426 } rcvq_space; 427 428 /* TCP-specific MTU probe information. */ 429 struct { 430 u32 probe_seq_start; 431 u32 probe_seq_end; 432 } mtu_probe; 433 u32 mtu_info; /* We received an ICMP_FRAG_NEEDED / ICMPV6_PKT_TOOBIG 434 * while socket was owned by user. 435 */ 436 #if IS_ENABLED(CONFIG_MPTCP) 437 bool is_mptcp; 438 #endif 439 440 #ifdef CONFIG_TCP_MD5SIG 441 /* TCP AF-Specific parts; only used by MD5 Signature support so far */ 442 const struct tcp_sock_af_ops *af_specific; 443 444 /* TCP MD5 Signature Option information */ 445 struct tcp_md5sig_info __rcu *md5sig_info; 446 #endif 447 448 /* TCP fastopen related information */ 449 struct tcp_fastopen_request *fastopen_req; 450 /* fastopen_rsk points to request_sock that resulted in this big 451 * socket. Used to retransmit SYNACKs etc. 452 */ 453 struct request_sock __rcu *fastopen_rsk; 454 u32 *saved_syn; 455 }; 456 457 enum tsq_enum { 458 TSQ_THROTTLED, 459 TSQ_QUEUED, 460 TCP_TSQ_DEFERRED, /* tcp_tasklet_func() found socket was owned */ 461 TCP_WRITE_TIMER_DEFERRED, /* tcp_write_timer() found socket was owned */ 462 TCP_DELACK_TIMER_DEFERRED, /* tcp_delack_timer() found socket was owned */ 463 TCP_MTU_REDUCED_DEFERRED, /* tcp_v{4|6}_err() could not call 464 * tcp_v{4|6}_mtu_reduced() 465 */ 466 }; 467 468 enum tsq_flags { 469 TSQF_THROTTLED = (1UL << TSQ_THROTTLED), 470 TSQF_QUEUED = (1UL << TSQ_QUEUED), 471 TCPF_TSQ_DEFERRED = (1UL << TCP_TSQ_DEFERRED), 472 TCPF_WRITE_TIMER_DEFERRED = (1UL << TCP_WRITE_TIMER_DEFERRED), 473 TCPF_DELACK_TIMER_DEFERRED = (1UL << TCP_DELACK_TIMER_DEFERRED), 474 TCPF_MTU_REDUCED_DEFERRED = (1UL << TCP_MTU_REDUCED_DEFERRED), 475 }; 476 477 static inline struct tcp_sock *tcp_sk(const struct sock *sk) 478 { 479 return (struct tcp_sock *)sk; 480 } 481 482 struct tcp_timewait_sock { 483 struct inet_timewait_sock tw_sk; 484 #define tw_rcv_nxt tw_sk.__tw_common.skc_tw_rcv_nxt 485 #define tw_snd_nxt tw_sk.__tw_common.skc_tw_snd_nxt 486 u32 tw_rcv_wnd; 487 u32 tw_ts_offset; 488 u32 tw_ts_recent; 489 490 /* The time we sent the last out-of-window ACK: */ 491 u32 tw_last_oow_ack_time; 492 493 int tw_ts_recent_stamp; 494 u32 tw_tx_delay; 495 #ifdef CONFIG_TCP_MD5SIG 496 struct tcp_md5sig_key *tw_md5_key; 497 #endif 498 }; 499 500 static inline struct tcp_timewait_sock *tcp_twsk(const struct sock *sk) 501 { 502 return (struct tcp_timewait_sock *)sk; 503 } 504 505 static inline bool tcp_passive_fastopen(const struct sock *sk) 506 { 507 return sk->sk_state == TCP_SYN_RECV && 508 rcu_access_pointer(tcp_sk(sk)->fastopen_rsk) != NULL; 509 } 510 511 static inline void fastopen_queue_tune(struct sock *sk, int backlog) 512 { 513 struct request_sock_queue *queue = &inet_csk(sk)->icsk_accept_queue; 514 int somaxconn = READ_ONCE(sock_net(sk)->core.sysctl_somaxconn); 515 516 queue->fastopenq.max_qlen = min_t(unsigned int, backlog, somaxconn); 517 } 518 519 static inline void tcp_move_syn(struct tcp_sock *tp, 520 struct request_sock *req) 521 { 522 tp->saved_syn = req->saved_syn; 523 req->saved_syn = NULL; 524 } 525 526 static inline void tcp_saved_syn_free(struct tcp_sock *tp) 527 { 528 kfree(tp->saved_syn); 529 tp->saved_syn = NULL; 530 } 531 532 struct sk_buff *tcp_get_timestamping_opt_stats(const struct sock *sk); 533 534 static inline u16 tcp_mss_clamp(const struct tcp_sock *tp, u16 mss) 535 { 536 /* We use READ_ONCE() here because socket might not be locked. 537 * This happens for listeners. 538 */ 539 u16 user_mss = READ_ONCE(tp->rx_opt.user_mss); 540 541 return (user_mss && user_mss < mss) ? user_mss : mss; 542 } 543 544 int tcp_skb_shift(struct sk_buff *to, struct sk_buff *from, int pcount, 545 int shiftlen); 546 547 #endif /* _LINUX_TCP_H */ 548