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 union { 62 u8 val[TCP_FASTOPEN_COOKIE_MAX]; 63 #if IS_ENABLED(CONFIG_IPV6) 64 struct in6_addr addr; 65 #endif 66 }; 67 s8 len; 68 bool exp; /* In RFC6994 experimental option format */ 69 }; 70 71 /* This defines a selective acknowledgement block. */ 72 struct tcp_sack_block_wire { 73 __be32 start_seq; 74 __be32 end_seq; 75 }; 76 77 struct tcp_sack_block { 78 u32 start_seq; 79 u32 end_seq; 80 }; 81 82 /*These are used to set the sack_ok field in struct tcp_options_received */ 83 #define TCP_SACK_SEEN (1 << 0) /*1 = peer is SACK capable, */ 84 #define TCP_DSACK_SEEN (1 << 2) /*1 = DSACK was received from peer*/ 85 86 struct tcp_options_received { 87 /* PAWS/RTTM data */ 88 int ts_recent_stamp;/* Time we stored ts_recent (for aging) */ 89 u32 ts_recent; /* Time stamp to echo next */ 90 u32 rcv_tsval; /* Time stamp value */ 91 u32 rcv_tsecr; /* Time stamp echo reply */ 92 u16 saw_tstamp : 1, /* Saw TIMESTAMP on last packet */ 93 tstamp_ok : 1, /* TIMESTAMP seen on SYN packet */ 94 dsack : 1, /* D-SACK is scheduled */ 95 wscale_ok : 1, /* Wscale seen on SYN packet */ 96 sack_ok : 3, /* SACK seen on SYN packet */ 97 smc_ok : 1, /* SMC seen on SYN packet */ 98 snd_wscale : 4, /* Window scaling received from sender */ 99 rcv_wscale : 4; /* Window scaling to send to receiver */ 100 u8 num_sacks; /* Number of SACK blocks */ 101 u16 user_mss; /* mss requested by user in ioctl */ 102 u16 mss_clamp; /* Maximal mss, negotiated at connection setup */ 103 }; 104 105 static inline void tcp_clear_options(struct tcp_options_received *rx_opt) 106 { 107 rx_opt->tstamp_ok = rx_opt->sack_ok = 0; 108 rx_opt->wscale_ok = rx_opt->snd_wscale = 0; 109 #if IS_ENABLED(CONFIG_SMC) 110 rx_opt->smc_ok = 0; 111 #endif 112 } 113 114 /* This is the max number of SACKS that we'll generate and process. It's safe 115 * to increase this, although since: 116 * size = TCPOLEN_SACK_BASE_ALIGNED (4) + n * TCPOLEN_SACK_PERBLOCK (8) 117 * only four options will fit in a standard TCP header */ 118 #define TCP_NUM_SACKS 4 119 120 struct tcp_request_sock_ops; 121 122 struct tcp_request_sock { 123 struct inet_request_sock req; 124 const struct tcp_request_sock_ops *af_specific; 125 u64 snt_synack; /* first SYNACK sent time */ 126 bool tfo_listener; 127 u32 txhash; 128 u32 rcv_isn; 129 u32 snt_isn; 130 u32 ts_off; 131 u32 last_oow_ack_time; /* last SYNACK */ 132 u32 rcv_nxt; /* the ack # by SYNACK. For 133 * FastOpen it's the seq# 134 * after data-in-SYN. 135 */ 136 }; 137 138 static inline struct tcp_request_sock *tcp_rsk(const struct request_sock *req) 139 { 140 return (struct tcp_request_sock *)req; 141 } 142 143 struct tcp_sock { 144 /* inet_connection_sock has to be the first member of tcp_sock */ 145 struct inet_connection_sock inet_conn; 146 u16 tcp_header_len; /* Bytes of tcp header to send */ 147 u16 gso_segs; /* Max number of segs per GSO packet */ 148 149 /* 150 * Header prediction flags 151 * 0x5?10 << 16 + snd_wnd in net byte order 152 */ 153 __be32 pred_flags; 154 155 /* 156 * RFC793 variables by their proper names. This means you can 157 * read the code and the spec side by side (and laugh ...) 158 * See RFC793 and RFC1122. The RFC writes these in capitals. 159 */ 160 u64 bytes_received; /* RFC4898 tcpEStatsAppHCThruOctetsReceived 161 * sum(delta(rcv_nxt)), or how many bytes 162 * were acked. 163 */ 164 u32 segs_in; /* RFC4898 tcpEStatsPerfSegsIn 165 * total number of segments in. 166 */ 167 u32 data_segs_in; /* RFC4898 tcpEStatsPerfDataSegsIn 168 * total number of data segments in. 169 */ 170 u32 rcv_nxt; /* What we want to receive next */ 171 u32 copied_seq; /* Head of yet unread data */ 172 u32 rcv_wup; /* rcv_nxt on last window update sent */ 173 u32 snd_nxt; /* Next sequence we send */ 174 u32 segs_out; /* RFC4898 tcpEStatsPerfSegsOut 175 * The total number of segments sent. 176 */ 177 u32 data_segs_out; /* RFC4898 tcpEStatsPerfDataSegsOut 178 * total number of data segments sent. 179 */ 180 u64 bytes_sent; /* RFC4898 tcpEStatsPerfHCDataOctetsOut 181 * total number of data bytes sent. 182 */ 183 u64 bytes_acked; /* RFC4898 tcpEStatsAppHCThruOctetsAcked 184 * sum(delta(snd_una)), or how many bytes 185 * were acked. 186 */ 187 u32 dsack_dups; /* RFC4898 tcpEStatsStackDSACKDups 188 * total number of DSACK blocks received 189 */ 190 u32 snd_una; /* First byte we want an ack for */ 191 u32 snd_sml; /* Last byte of the most recently transmitted small packet */ 192 u32 rcv_tstamp; /* timestamp of last received ACK (for keepalives) */ 193 u32 lsndtime; /* timestamp of last sent data packet (for restart window) */ 194 u32 last_oow_ack_time; /* timestamp of last out-of-window ACK */ 195 u32 compressed_ack_rcv_nxt; 196 197 u32 tsoffset; /* timestamp offset */ 198 199 struct list_head tsq_node; /* anchor in tsq_tasklet.head list */ 200 struct list_head tsorted_sent_queue; /* time-sorted sent but un-SACKed skbs */ 201 202 u32 snd_wl1; /* Sequence for window update */ 203 u32 snd_wnd; /* The window we expect to receive */ 204 u32 max_window; /* Maximal window ever seen from peer */ 205 u32 mss_cache; /* Cached effective mss, not including SACKS */ 206 207 u32 window_clamp; /* Maximal window to advertise */ 208 u32 rcv_ssthresh; /* Current window clamp */ 209 210 /* Information of the most recently (s)acked skb */ 211 struct tcp_rack { 212 u64 mstamp; /* (Re)sent time of the skb */ 213 u32 rtt_us; /* Associated RTT */ 214 u32 end_seq; /* Ending TCP sequence of the skb */ 215 u32 last_delivered; /* tp->delivered at last reo_wnd adj */ 216 u8 reo_wnd_steps; /* Allowed reordering window */ 217 #define TCP_RACK_RECOVERY_THRESH 16 218 u8 reo_wnd_persist:5, /* No. of recovery since last adj */ 219 dsack_seen:1, /* Whether DSACK seen after last adj */ 220 advanced:1; /* mstamp advanced since last lost marking */ 221 } rack; 222 u16 advmss; /* Advertised MSS */ 223 u8 compressed_ack; 224 u32 chrono_start; /* Start time in jiffies of a TCP chrono */ 225 u32 chrono_stat[3]; /* Time in jiffies for chrono_stat stats */ 226 u8 chrono_type:2, /* current chronograph type */ 227 rate_app_limited:1, /* rate_{delivered,interval_us} limited? */ 228 fastopen_connect:1, /* FASTOPEN_CONNECT sockopt */ 229 fastopen_no_cookie:1, /* Allow send/recv SYN+data without a cookie */ 230 is_sack_reneg:1, /* in recovery from loss with SACK reneg? */ 231 unused:2; 232 u8 nonagle : 4,/* Disable Nagle algorithm? */ 233 thin_lto : 1,/* Use linear timeouts for thin streams */ 234 recvmsg_inq : 1,/* Indicate # of bytes in queue upon recvmsg */ 235 repair : 1, 236 frto : 1;/* F-RTO (RFC5682) activated in CA_Loss */ 237 u8 repair_queue; 238 u8 syn_data:1, /* SYN includes data */ 239 syn_fastopen:1, /* SYN includes Fast Open option */ 240 syn_fastopen_exp:1,/* SYN includes Fast Open exp. option */ 241 syn_fastopen_ch:1, /* Active TFO re-enabling probe */ 242 syn_data_acked:1,/* data in SYN is acked by SYN-ACK */ 243 save_syn:1, /* Save headers of SYN packet */ 244 is_cwnd_limited:1,/* forward progress limited by snd_cwnd? */ 245 syn_smc:1; /* SYN includes SMC */ 246 u32 tlp_high_seq; /* snd_nxt at the time of TLP retransmit. */ 247 248 u32 tcp_tx_delay; /* delay (in usec) added to TX packets */ 249 u64 tcp_wstamp_ns; /* departure time for next sent data packet */ 250 u64 tcp_clock_cache; /* cache last tcp_clock_ns() (see tcp_mstamp_refresh()) */ 251 252 /* RTT measurement */ 253 u64 tcp_mstamp; /* most recent packet received/sent */ 254 u32 srtt_us; /* smoothed round trip time << 3 in usecs */ 255 u32 mdev_us; /* medium deviation */ 256 u32 mdev_max_us; /* maximal mdev for the last rtt period */ 257 u32 rttvar_us; /* smoothed mdev_max */ 258 u32 rtt_seq; /* sequence number to update rttvar */ 259 struct minmax rtt_min; 260 261 u32 packets_out; /* Packets which are "in flight" */ 262 u32 retrans_out; /* Retransmitted packets out */ 263 u32 max_packets_out; /* max packets_out in last window */ 264 u32 max_packets_seq; /* right edge of max_packets_out flight */ 265 266 u16 urg_data; /* Saved octet of OOB data and control flags */ 267 u8 ecn_flags; /* ECN status bits. */ 268 u8 keepalive_probes; /* num of allowed keep alive probes */ 269 u32 reordering; /* Packet reordering metric. */ 270 u32 reord_seen; /* number of data packet reordering events */ 271 u32 snd_up; /* Urgent pointer */ 272 273 /* 274 * Options received (usually on last packet, some only on SYN packets). 275 */ 276 struct tcp_options_received rx_opt; 277 278 /* 279 * Slow start and congestion control (see also Nagle, and Karn & Partridge) 280 */ 281 u32 snd_ssthresh; /* Slow start size threshold */ 282 u32 snd_cwnd; /* Sending congestion window */ 283 u32 snd_cwnd_cnt; /* Linear increase counter */ 284 u32 snd_cwnd_clamp; /* Do not allow snd_cwnd to grow above this */ 285 u32 snd_cwnd_used; 286 u32 snd_cwnd_stamp; 287 u32 prior_cwnd; /* cwnd right before starting loss recovery */ 288 u32 prr_delivered; /* Number of newly delivered packets to 289 * receiver in Recovery. */ 290 u32 prr_out; /* Total number of pkts sent during Recovery. */ 291 u32 delivered; /* Total data packets delivered incl. rexmits */ 292 u32 delivered_ce; /* Like the above but only ECE marked packets */ 293 u32 lost; /* Total data packets lost incl. rexmits */ 294 u32 app_limited; /* limited until "delivered" reaches this val */ 295 u64 first_tx_mstamp; /* start of window send phase */ 296 u64 delivered_mstamp; /* time we reached "delivered" */ 297 u32 rate_delivered; /* saved rate sample: packets delivered */ 298 u32 rate_interval_us; /* saved rate sample: time elapsed */ 299 300 u32 rcv_wnd; /* Current receiver window */ 301 u32 write_seq; /* Tail(+1) of data held in tcp send buffer */ 302 u32 notsent_lowat; /* TCP_NOTSENT_LOWAT */ 303 u32 pushed_seq; /* Last pushed seq, required to talk to windows */ 304 u32 lost_out; /* Lost packets */ 305 u32 sacked_out; /* SACK'd packets */ 306 307 struct hrtimer pacing_timer; 308 struct hrtimer compressed_ack_timer; 309 310 /* from STCP, retrans queue hinting */ 311 struct sk_buff* lost_skb_hint; 312 struct sk_buff *retransmit_skb_hint; 313 314 /* OOO segments go in this rbtree. Socket lock must be held. */ 315 struct rb_root out_of_order_queue; 316 struct sk_buff *ooo_last_skb; /* cache rb_last(out_of_order_queue) */ 317 318 /* SACKs data, these 2 need to be together (see tcp_options_write) */ 319 struct tcp_sack_block duplicate_sack[1]; /* D-SACK block */ 320 struct tcp_sack_block selective_acks[4]; /* The SACKS themselves*/ 321 322 struct tcp_sack_block recv_sack_cache[4]; 323 324 struct sk_buff *highest_sack; /* skb just after the highest 325 * skb with SACKed bit set 326 * (validity guaranteed only if 327 * sacked_out > 0) 328 */ 329 330 int lost_cnt_hint; 331 332 u32 prior_ssthresh; /* ssthresh saved at recovery start */ 333 u32 high_seq; /* snd_nxt at onset of congestion */ 334 335 u32 retrans_stamp; /* Timestamp of the last retransmit, 336 * also used in SYN-SENT to remember stamp of 337 * the first SYN. */ 338 u32 undo_marker; /* snd_una upon a new recovery episode. */ 339 int undo_retrans; /* number of undoable retransmissions. */ 340 u64 bytes_retrans; /* RFC4898 tcpEStatsPerfOctetsRetrans 341 * Total data bytes retransmitted 342 */ 343 u32 total_retrans; /* Total retransmits for entire connection */ 344 345 u32 urg_seq; /* Seq of received urgent pointer */ 346 unsigned int keepalive_time; /* time before keep alive takes place */ 347 unsigned int keepalive_intvl; /* time interval between keep alive probes */ 348 349 int linger2; 350 351 352 /* Sock_ops bpf program related variables */ 353 #ifdef CONFIG_BPF 354 u8 bpf_sock_ops_cb_flags; /* Control calling BPF programs 355 * values defined in uapi/linux/tcp.h 356 */ 357 #define BPF_SOCK_OPS_TEST_FLAG(TP, ARG) (TP->bpf_sock_ops_cb_flags & ARG) 358 #else 359 #define BPF_SOCK_OPS_TEST_FLAG(TP, ARG) 0 360 #endif 361 362 /* Receiver side RTT estimation */ 363 u32 rcv_rtt_last_tsecr; 364 struct { 365 u32 rtt_us; 366 u32 seq; 367 u64 time; 368 } rcv_rtt_est; 369 370 /* Receiver queue space */ 371 struct { 372 u32 space; 373 u32 seq; 374 u64 time; 375 } rcvq_space; 376 377 /* TCP-specific MTU probe information. */ 378 struct { 379 u32 probe_seq_start; 380 u32 probe_seq_end; 381 } mtu_probe; 382 u32 mtu_info; /* We received an ICMP_FRAG_NEEDED / ICMPV6_PKT_TOOBIG 383 * while socket was owned by user. 384 */ 385 386 #ifdef CONFIG_TCP_MD5SIG 387 /* TCP AF-Specific parts; only used by MD5 Signature support so far */ 388 const struct tcp_sock_af_ops *af_specific; 389 390 /* TCP MD5 Signature Option information */ 391 struct tcp_md5sig_info __rcu *md5sig_info; 392 #endif 393 394 /* TCP fastopen related information */ 395 struct tcp_fastopen_request *fastopen_req; 396 /* fastopen_rsk points to request_sock that resulted in this big 397 * socket. Used to retransmit SYNACKs etc. 398 */ 399 struct request_sock *fastopen_rsk; 400 u32 *saved_syn; 401 }; 402 403 enum tsq_enum { 404 TSQ_THROTTLED, 405 TSQ_QUEUED, 406 TCP_TSQ_DEFERRED, /* tcp_tasklet_func() found socket was owned */ 407 TCP_WRITE_TIMER_DEFERRED, /* tcp_write_timer() found socket was owned */ 408 TCP_DELACK_TIMER_DEFERRED, /* tcp_delack_timer() found socket was owned */ 409 TCP_MTU_REDUCED_DEFERRED, /* tcp_v{4|6}_err() could not call 410 * tcp_v{4|6}_mtu_reduced() 411 */ 412 }; 413 414 enum tsq_flags { 415 TSQF_THROTTLED = (1UL << TSQ_THROTTLED), 416 TSQF_QUEUED = (1UL << TSQ_QUEUED), 417 TCPF_TSQ_DEFERRED = (1UL << TCP_TSQ_DEFERRED), 418 TCPF_WRITE_TIMER_DEFERRED = (1UL << TCP_WRITE_TIMER_DEFERRED), 419 TCPF_DELACK_TIMER_DEFERRED = (1UL << TCP_DELACK_TIMER_DEFERRED), 420 TCPF_MTU_REDUCED_DEFERRED = (1UL << TCP_MTU_REDUCED_DEFERRED), 421 }; 422 423 static inline struct tcp_sock *tcp_sk(const struct sock *sk) 424 { 425 return (struct tcp_sock *)sk; 426 } 427 428 struct tcp_timewait_sock { 429 struct inet_timewait_sock tw_sk; 430 #define tw_rcv_nxt tw_sk.__tw_common.skc_tw_rcv_nxt 431 #define tw_snd_nxt tw_sk.__tw_common.skc_tw_snd_nxt 432 u32 tw_rcv_wnd; 433 u32 tw_ts_offset; 434 u32 tw_ts_recent; 435 436 /* The time we sent the last out-of-window ACK: */ 437 u32 tw_last_oow_ack_time; 438 439 int tw_ts_recent_stamp; 440 u32 tw_tx_delay; 441 #ifdef CONFIG_TCP_MD5SIG 442 struct tcp_md5sig_key *tw_md5_key; 443 #endif 444 }; 445 446 static inline struct tcp_timewait_sock *tcp_twsk(const struct sock *sk) 447 { 448 return (struct tcp_timewait_sock *)sk; 449 } 450 451 static inline bool tcp_passive_fastopen(const struct sock *sk) 452 { 453 return (sk->sk_state == TCP_SYN_RECV && 454 tcp_sk(sk)->fastopen_rsk != NULL); 455 } 456 457 static inline void fastopen_queue_tune(struct sock *sk, int backlog) 458 { 459 struct request_sock_queue *queue = &inet_csk(sk)->icsk_accept_queue; 460 int somaxconn = READ_ONCE(sock_net(sk)->core.sysctl_somaxconn); 461 462 queue->fastopenq.max_qlen = min_t(unsigned int, backlog, somaxconn); 463 } 464 465 static inline void tcp_move_syn(struct tcp_sock *tp, 466 struct request_sock *req) 467 { 468 tp->saved_syn = req->saved_syn; 469 req->saved_syn = NULL; 470 } 471 472 static inline void tcp_saved_syn_free(struct tcp_sock *tp) 473 { 474 kfree(tp->saved_syn); 475 tp->saved_syn = NULL; 476 } 477 478 struct sk_buff *tcp_get_timestamping_opt_stats(const struct sock *sk); 479 480 static inline u16 tcp_mss_clamp(const struct tcp_sock *tp, u16 mss) 481 { 482 /* We use READ_ONCE() here because socket might not be locked. 483 * This happens for listeners. 484 */ 485 u16 user_mss = READ_ONCE(tp->rx_opt.user_mss); 486 487 return (user_mss && user_mss < mss) ? user_mss : mss; 488 } 489 #endif /* _LINUX_TCP_H */ 490