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