1 /* 2 * INET An implementation of the TCP/IP protocol suite for the LINUX 3 * operating system. INET is implemented using the BSD Socket 4 * interface as the means of communication with the user level. 5 * 6 * Definitions for the TCP module. 7 * 8 * Version: @(#)tcp.h 1.0.5 05/23/93 9 * 10 * Authors: Ross Biro 11 * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG> 12 * 13 * This program is free software; you can redistribute it and/or 14 * modify it under the terms of the GNU General Public License 15 * as published by the Free Software Foundation; either version 16 * 2 of the License, or (at your option) any later version. 17 */ 18 #ifndef _TCP_H 19 #define _TCP_H 20 21 #define FASTRETRANS_DEBUG 1 22 23 #include <linux/list.h> 24 #include <linux/tcp.h> 25 #include <linux/bug.h> 26 #include <linux/slab.h> 27 #include <linux/cache.h> 28 #include <linux/percpu.h> 29 #include <linux/skbuff.h> 30 #include <linux/cryptohash.h> 31 #include <linux/kref.h> 32 #include <linux/ktime.h> 33 34 #include <net/inet_connection_sock.h> 35 #include <net/inet_timewait_sock.h> 36 #include <net/inet_hashtables.h> 37 #include <net/checksum.h> 38 #include <net/request_sock.h> 39 #include <net/sock.h> 40 #include <net/snmp.h> 41 #include <net/ip.h> 42 #include <net/tcp_states.h> 43 #include <net/inet_ecn.h> 44 #include <net/dst.h> 45 46 #include <linux/seq_file.h> 47 #include <linux/memcontrol.h> 48 #include <linux/bpf-cgroup.h> 49 50 extern struct inet_hashinfo tcp_hashinfo; 51 52 extern struct percpu_counter tcp_orphan_count; 53 void tcp_time_wait(struct sock *sk, int state, int timeo); 54 55 #define MAX_TCP_HEADER (128 + MAX_HEADER) 56 #define MAX_TCP_OPTION_SPACE 40 57 58 /* 59 * Never offer a window over 32767 without using window scaling. Some 60 * poor stacks do signed 16bit maths! 61 */ 62 #define MAX_TCP_WINDOW 32767U 63 64 /* Minimal accepted MSS. It is (60+60+8) - (20+20). */ 65 #define TCP_MIN_MSS 88U 66 67 /* The least MTU to use for probing */ 68 #define TCP_BASE_MSS 1024 69 70 /* probing interval, default to 10 minutes as per RFC4821 */ 71 #define TCP_PROBE_INTERVAL 600 72 73 /* Specify interval when tcp mtu probing will stop */ 74 #define TCP_PROBE_THRESHOLD 8 75 76 /* After receiving this amount of duplicate ACKs fast retransmit starts. */ 77 #define TCP_FASTRETRANS_THRESH 3 78 79 /* Maximal number of ACKs sent quickly to accelerate slow-start. */ 80 #define TCP_MAX_QUICKACKS 16U 81 82 /* Maximal number of window scale according to RFC1323 */ 83 #define TCP_MAX_WSCALE 14U 84 85 /* urg_data states */ 86 #define TCP_URG_VALID 0x0100 87 #define TCP_URG_NOTYET 0x0200 88 #define TCP_URG_READ 0x0400 89 90 #define TCP_RETR1 3 /* 91 * This is how many retries it does before it 92 * tries to figure out if the gateway is 93 * down. Minimal RFC value is 3; it corresponds 94 * to ~3sec-8min depending on RTO. 95 */ 96 97 #define TCP_RETR2 15 /* 98 * This should take at least 99 * 90 minutes to time out. 100 * RFC1122 says that the limit is 100 sec. 101 * 15 is ~13-30min depending on RTO. 102 */ 103 104 #define TCP_SYN_RETRIES 6 /* This is how many retries are done 105 * when active opening a connection. 106 * RFC1122 says the minimum retry MUST 107 * be at least 180secs. Nevertheless 108 * this value is corresponding to 109 * 63secs of retransmission with the 110 * current initial RTO. 111 */ 112 113 #define TCP_SYNACK_RETRIES 5 /* This is how may retries are done 114 * when passive opening a connection. 115 * This is corresponding to 31secs of 116 * retransmission with the current 117 * initial RTO. 118 */ 119 120 #define TCP_TIMEWAIT_LEN (60*HZ) /* how long to wait to destroy TIME-WAIT 121 * state, about 60 seconds */ 122 #define TCP_FIN_TIMEOUT TCP_TIMEWAIT_LEN 123 /* BSD style FIN_WAIT2 deadlock breaker. 124 * It used to be 3min, new value is 60sec, 125 * to combine FIN-WAIT-2 timeout with 126 * TIME-WAIT timer. 127 */ 128 129 #define TCP_DELACK_MAX ((unsigned)(HZ/5)) /* maximal time to delay before sending an ACK */ 130 #if HZ >= 100 131 #define TCP_DELACK_MIN ((unsigned)(HZ/25)) /* minimal time to delay before sending an ACK */ 132 #define TCP_ATO_MIN ((unsigned)(HZ/25)) 133 #else 134 #define TCP_DELACK_MIN 4U 135 #define TCP_ATO_MIN 4U 136 #endif 137 #define TCP_RTO_MAX ((unsigned)(120*HZ)) 138 #define TCP_RTO_MIN ((unsigned)(HZ/5)) 139 #define TCP_TIMEOUT_MIN (2U) /* Min timeout for TCP timers in jiffies */ 140 #define TCP_TIMEOUT_INIT ((unsigned)(1*HZ)) /* RFC6298 2.1 initial RTO value */ 141 #define TCP_TIMEOUT_FALLBACK ((unsigned)(3*HZ)) /* RFC 1122 initial RTO value, now 142 * used as a fallback RTO for the 143 * initial data transmission if no 144 * valid RTT sample has been acquired, 145 * most likely due to retrans in 3WHS. 146 */ 147 148 #define TCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ/2U)) /* Maximal interval between probes 149 * for local resources. 150 */ 151 #define TCP_KEEPALIVE_TIME (120*60*HZ) /* two hours */ 152 #define TCP_KEEPALIVE_PROBES 9 /* Max of 9 keepalive probes */ 153 #define TCP_KEEPALIVE_INTVL (75*HZ) 154 155 #define MAX_TCP_KEEPIDLE 32767 156 #define MAX_TCP_KEEPINTVL 32767 157 #define MAX_TCP_KEEPCNT 127 158 #define MAX_TCP_SYNCNT 127 159 160 #define TCP_SYNQ_INTERVAL (HZ/5) /* Period of SYNACK timer */ 161 162 #define TCP_PAWS_24DAYS (60 * 60 * 24 * 24) 163 #define TCP_PAWS_MSL 60 /* Per-host timestamps are invalidated 164 * after this time. It should be equal 165 * (or greater than) TCP_TIMEWAIT_LEN 166 * to provide reliability equal to one 167 * provided by timewait state. 168 */ 169 #define TCP_PAWS_WINDOW 1 /* Replay window for per-host 170 * timestamps. It must be less than 171 * minimal timewait lifetime. 172 */ 173 /* 174 * TCP option 175 */ 176 177 #define TCPOPT_NOP 1 /* Padding */ 178 #define TCPOPT_EOL 0 /* End of options */ 179 #define TCPOPT_MSS 2 /* Segment size negotiating */ 180 #define TCPOPT_WINDOW 3 /* Window scaling */ 181 #define TCPOPT_SACK_PERM 4 /* SACK Permitted */ 182 #define TCPOPT_SACK 5 /* SACK Block */ 183 #define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */ 184 #define TCPOPT_MD5SIG 19 /* MD5 Signature (RFC2385) */ 185 #define TCPOPT_FASTOPEN 34 /* Fast open (RFC7413) */ 186 #define TCPOPT_EXP 254 /* Experimental */ 187 /* Magic number to be after the option value for sharing TCP 188 * experimental options. See draft-ietf-tcpm-experimental-options-00.txt 189 */ 190 #define TCPOPT_FASTOPEN_MAGIC 0xF989 191 #define TCPOPT_SMC_MAGIC 0xE2D4C3D9 192 193 /* 194 * TCP option lengths 195 */ 196 197 #define TCPOLEN_MSS 4 198 #define TCPOLEN_WINDOW 3 199 #define TCPOLEN_SACK_PERM 2 200 #define TCPOLEN_TIMESTAMP 10 201 #define TCPOLEN_MD5SIG 18 202 #define TCPOLEN_FASTOPEN_BASE 2 203 #define TCPOLEN_EXP_FASTOPEN_BASE 4 204 #define TCPOLEN_EXP_SMC_BASE 6 205 206 /* But this is what stacks really send out. */ 207 #define TCPOLEN_TSTAMP_ALIGNED 12 208 #define TCPOLEN_WSCALE_ALIGNED 4 209 #define TCPOLEN_SACKPERM_ALIGNED 4 210 #define TCPOLEN_SACK_BASE 2 211 #define TCPOLEN_SACK_BASE_ALIGNED 4 212 #define TCPOLEN_SACK_PERBLOCK 8 213 #define TCPOLEN_MD5SIG_ALIGNED 20 214 #define TCPOLEN_MSS_ALIGNED 4 215 #define TCPOLEN_EXP_SMC_BASE_ALIGNED 8 216 217 /* Flags in tp->nonagle */ 218 #define TCP_NAGLE_OFF 1 /* Nagle's algo is disabled */ 219 #define TCP_NAGLE_CORK 2 /* Socket is corked */ 220 #define TCP_NAGLE_PUSH 4 /* Cork is overridden for already queued data */ 221 222 /* TCP thin-stream limits */ 223 #define TCP_THIN_LINEAR_RETRIES 6 /* After 6 linear retries, do exp. backoff */ 224 225 /* TCP initial congestion window as per rfc6928 */ 226 #define TCP_INIT_CWND 10 227 228 /* Bit Flags for sysctl_tcp_fastopen */ 229 #define TFO_CLIENT_ENABLE 1 230 #define TFO_SERVER_ENABLE 2 231 #define TFO_CLIENT_NO_COOKIE 4 /* Data in SYN w/o cookie option */ 232 233 /* Accept SYN data w/o any cookie option */ 234 #define TFO_SERVER_COOKIE_NOT_REQD 0x200 235 236 /* Force enable TFO on all listeners, i.e., not requiring the 237 * TCP_FASTOPEN socket option. 238 */ 239 #define TFO_SERVER_WO_SOCKOPT1 0x400 240 241 242 /* sysctl variables for tcp */ 243 extern int sysctl_tcp_max_orphans; 244 extern long sysctl_tcp_mem[3]; 245 246 #define TCP_RACK_LOSS_DETECTION 0x1 /* Use RACK to detect losses */ 247 #define TCP_RACK_STATIC_REO_WND 0x2 /* Use static RACK reo wnd */ 248 249 extern atomic_long_t tcp_memory_allocated; 250 extern struct percpu_counter tcp_sockets_allocated; 251 extern unsigned long tcp_memory_pressure; 252 253 /* optimized version of sk_under_memory_pressure() for TCP sockets */ 254 static inline bool tcp_under_memory_pressure(const struct sock *sk) 255 { 256 if (mem_cgroup_sockets_enabled && sk->sk_memcg && 257 mem_cgroup_under_socket_pressure(sk->sk_memcg)) 258 return true; 259 260 return tcp_memory_pressure; 261 } 262 /* 263 * The next routines deal with comparing 32 bit unsigned ints 264 * and worry about wraparound (automatic with unsigned arithmetic). 265 */ 266 267 static inline bool before(__u32 seq1, __u32 seq2) 268 { 269 return (__s32)(seq1-seq2) < 0; 270 } 271 #define after(seq2, seq1) before(seq1, seq2) 272 273 /* is s2<=s1<=s3 ? */ 274 static inline bool between(__u32 seq1, __u32 seq2, __u32 seq3) 275 { 276 return seq3 - seq2 >= seq1 - seq2; 277 } 278 279 static inline bool tcp_out_of_memory(struct sock *sk) 280 { 281 if (sk->sk_wmem_queued > SOCK_MIN_SNDBUF && 282 sk_memory_allocated(sk) > sk_prot_mem_limits(sk, 2)) 283 return true; 284 return false; 285 } 286 287 void sk_forced_mem_schedule(struct sock *sk, int size); 288 289 static inline bool tcp_too_many_orphans(struct sock *sk, int shift) 290 { 291 struct percpu_counter *ocp = sk->sk_prot->orphan_count; 292 int orphans = percpu_counter_read_positive(ocp); 293 294 if (orphans << shift > sysctl_tcp_max_orphans) { 295 orphans = percpu_counter_sum_positive(ocp); 296 if (orphans << shift > sysctl_tcp_max_orphans) 297 return true; 298 } 299 return false; 300 } 301 302 bool tcp_check_oom(struct sock *sk, int shift); 303 304 305 extern struct proto tcp_prot; 306 307 #define TCP_INC_STATS(net, field) SNMP_INC_STATS((net)->mib.tcp_statistics, field) 308 #define __TCP_INC_STATS(net, field) __SNMP_INC_STATS((net)->mib.tcp_statistics, field) 309 #define TCP_DEC_STATS(net, field) SNMP_DEC_STATS((net)->mib.tcp_statistics, field) 310 #define TCP_ADD_STATS(net, field, val) SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val) 311 312 void tcp_tasklet_init(void); 313 314 void tcp_v4_err(struct sk_buff *skb, u32); 315 316 void tcp_shutdown(struct sock *sk, int how); 317 318 int tcp_v4_early_demux(struct sk_buff *skb); 319 int tcp_v4_rcv(struct sk_buff *skb); 320 321 int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw); 322 int tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size); 323 int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size); 324 int tcp_sendpage(struct sock *sk, struct page *page, int offset, size_t size, 325 int flags); 326 int tcp_sendpage_locked(struct sock *sk, struct page *page, int offset, 327 size_t size, int flags); 328 ssize_t do_tcp_sendpages(struct sock *sk, struct page *page, int offset, 329 size_t size, int flags); 330 void tcp_release_cb(struct sock *sk); 331 void tcp_wfree(struct sk_buff *skb); 332 void tcp_write_timer_handler(struct sock *sk); 333 void tcp_delack_timer_handler(struct sock *sk); 334 int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg); 335 int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb); 336 void tcp_rcv_established(struct sock *sk, struct sk_buff *skb, 337 const struct tcphdr *th); 338 void tcp_rcv_space_adjust(struct sock *sk); 339 int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp); 340 void tcp_twsk_destructor(struct sock *sk); 341 ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos, 342 struct pipe_inode_info *pipe, size_t len, 343 unsigned int flags); 344 345 static inline void tcp_dec_quickack_mode(struct sock *sk, 346 const unsigned int pkts) 347 { 348 struct inet_connection_sock *icsk = inet_csk(sk); 349 350 if (icsk->icsk_ack.quick) { 351 if (pkts >= icsk->icsk_ack.quick) { 352 icsk->icsk_ack.quick = 0; 353 /* Leaving quickack mode we deflate ATO. */ 354 icsk->icsk_ack.ato = TCP_ATO_MIN; 355 } else 356 icsk->icsk_ack.quick -= pkts; 357 } 358 } 359 360 #define TCP_ECN_OK 1 361 #define TCP_ECN_QUEUE_CWR 2 362 #define TCP_ECN_DEMAND_CWR 4 363 #define TCP_ECN_SEEN 8 364 365 enum tcp_tw_status { 366 TCP_TW_SUCCESS = 0, 367 TCP_TW_RST = 1, 368 TCP_TW_ACK = 2, 369 TCP_TW_SYN = 3 370 }; 371 372 373 enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw, 374 struct sk_buff *skb, 375 const struct tcphdr *th); 376 struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb, 377 struct request_sock *req, bool fastopen, 378 bool *lost_race); 379 int tcp_child_process(struct sock *parent, struct sock *child, 380 struct sk_buff *skb); 381 void tcp_enter_loss(struct sock *sk); 382 void tcp_cwnd_reduction(struct sock *sk, int newly_acked_sacked, int flag); 383 void tcp_clear_retrans(struct tcp_sock *tp); 384 void tcp_update_metrics(struct sock *sk); 385 void tcp_init_metrics(struct sock *sk); 386 void tcp_metrics_init(void); 387 bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst); 388 void tcp_close(struct sock *sk, long timeout); 389 void tcp_init_sock(struct sock *sk); 390 void tcp_init_transfer(struct sock *sk, int bpf_op); 391 __poll_t tcp_poll(struct file *file, struct socket *sock, 392 struct poll_table_struct *wait); 393 int tcp_getsockopt(struct sock *sk, int level, int optname, 394 char __user *optval, int __user *optlen); 395 int tcp_setsockopt(struct sock *sk, int level, int optname, 396 char __user *optval, unsigned int optlen); 397 int compat_tcp_getsockopt(struct sock *sk, int level, int optname, 398 char __user *optval, int __user *optlen); 399 int compat_tcp_setsockopt(struct sock *sk, int level, int optname, 400 char __user *optval, unsigned int optlen); 401 void tcp_set_keepalive(struct sock *sk, int val); 402 void tcp_syn_ack_timeout(const struct request_sock *req); 403 int tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int nonblock, 404 int flags, int *addr_len); 405 void tcp_parse_options(const struct net *net, const struct sk_buff *skb, 406 struct tcp_options_received *opt_rx, 407 int estab, struct tcp_fastopen_cookie *foc); 408 const u8 *tcp_parse_md5sig_option(const struct tcphdr *th); 409 410 /* 411 * TCP v4 functions exported for the inet6 API 412 */ 413 414 void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb); 415 void tcp_v4_mtu_reduced(struct sock *sk); 416 void tcp_req_err(struct sock *sk, u32 seq, bool abort); 417 int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb); 418 struct sock *tcp_create_openreq_child(const struct sock *sk, 419 struct request_sock *req, 420 struct sk_buff *skb); 421 void tcp_ca_openreq_child(struct sock *sk, const struct dst_entry *dst); 422 struct sock *tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb, 423 struct request_sock *req, 424 struct dst_entry *dst, 425 struct request_sock *req_unhash, 426 bool *own_req); 427 int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb); 428 int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len); 429 int tcp_connect(struct sock *sk); 430 enum tcp_synack_type { 431 TCP_SYNACK_NORMAL, 432 TCP_SYNACK_FASTOPEN, 433 TCP_SYNACK_COOKIE, 434 }; 435 struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst, 436 struct request_sock *req, 437 struct tcp_fastopen_cookie *foc, 438 enum tcp_synack_type synack_type); 439 int tcp_disconnect(struct sock *sk, int flags); 440 441 void tcp_finish_connect(struct sock *sk, struct sk_buff *skb); 442 int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size); 443 void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb); 444 445 /* From syncookies.c */ 446 struct sock *tcp_get_cookie_sock(struct sock *sk, struct sk_buff *skb, 447 struct request_sock *req, 448 struct dst_entry *dst, u32 tsoff); 449 int __cookie_v4_check(const struct iphdr *iph, const struct tcphdr *th, 450 u32 cookie); 451 struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb); 452 #ifdef CONFIG_SYN_COOKIES 453 454 /* Syncookies use a monotonic timer which increments every 60 seconds. 455 * This counter is used both as a hash input and partially encoded into 456 * the cookie value. A cookie is only validated further if the delta 457 * between the current counter value and the encoded one is less than this, 458 * i.e. a sent cookie is valid only at most for 2*60 seconds (or less if 459 * the counter advances immediately after a cookie is generated). 460 */ 461 #define MAX_SYNCOOKIE_AGE 2 462 #define TCP_SYNCOOKIE_PERIOD (60 * HZ) 463 #define TCP_SYNCOOKIE_VALID (MAX_SYNCOOKIE_AGE * TCP_SYNCOOKIE_PERIOD) 464 465 /* syncookies: remember time of last synqueue overflow 466 * But do not dirty this field too often (once per second is enough) 467 * It is racy as we do not hold a lock, but race is very minor. 468 */ 469 static inline void tcp_synq_overflow(const struct sock *sk) 470 { 471 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp; 472 unsigned long now = jiffies; 473 474 if (time_after(now, last_overflow + HZ)) 475 tcp_sk(sk)->rx_opt.ts_recent_stamp = now; 476 } 477 478 /* syncookies: no recent synqueue overflow on this listening socket? */ 479 static inline bool tcp_synq_no_recent_overflow(const struct sock *sk) 480 { 481 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp; 482 483 return time_after(jiffies, last_overflow + TCP_SYNCOOKIE_VALID); 484 } 485 486 static inline u32 tcp_cookie_time(void) 487 { 488 u64 val = get_jiffies_64(); 489 490 do_div(val, TCP_SYNCOOKIE_PERIOD); 491 return val; 492 } 493 494 u32 __cookie_v4_init_sequence(const struct iphdr *iph, const struct tcphdr *th, 495 u16 *mssp); 496 __u32 cookie_v4_init_sequence(const struct sk_buff *skb, __u16 *mss); 497 u64 cookie_init_timestamp(struct request_sock *req); 498 bool cookie_timestamp_decode(const struct net *net, 499 struct tcp_options_received *opt); 500 bool cookie_ecn_ok(const struct tcp_options_received *opt, 501 const struct net *net, const struct dst_entry *dst); 502 503 /* From net/ipv6/syncookies.c */ 504 int __cookie_v6_check(const struct ipv6hdr *iph, const struct tcphdr *th, 505 u32 cookie); 506 struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb); 507 508 u32 __cookie_v6_init_sequence(const struct ipv6hdr *iph, 509 const struct tcphdr *th, u16 *mssp); 510 __u32 cookie_v6_init_sequence(const struct sk_buff *skb, __u16 *mss); 511 #endif 512 /* tcp_output.c */ 513 514 void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss, 515 int nonagle); 516 int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs); 517 int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs); 518 void tcp_retransmit_timer(struct sock *sk); 519 void tcp_xmit_retransmit_queue(struct sock *); 520 void tcp_simple_retransmit(struct sock *); 521 void tcp_enter_recovery(struct sock *sk, bool ece_ack); 522 int tcp_trim_head(struct sock *, struct sk_buff *, u32); 523 enum tcp_queue { 524 TCP_FRAG_IN_WRITE_QUEUE, 525 TCP_FRAG_IN_RTX_QUEUE, 526 }; 527 int tcp_fragment(struct sock *sk, enum tcp_queue tcp_queue, 528 struct sk_buff *skb, u32 len, 529 unsigned int mss_now, gfp_t gfp); 530 531 void tcp_send_probe0(struct sock *); 532 void tcp_send_partial(struct sock *); 533 int tcp_write_wakeup(struct sock *, int mib); 534 void tcp_send_fin(struct sock *sk); 535 void tcp_send_active_reset(struct sock *sk, gfp_t priority); 536 int tcp_send_synack(struct sock *); 537 void tcp_push_one(struct sock *, unsigned int mss_now); 538 void tcp_send_ack(struct sock *sk); 539 void tcp_send_delayed_ack(struct sock *sk); 540 void tcp_send_loss_probe(struct sock *sk); 541 bool tcp_schedule_loss_probe(struct sock *sk, bool advancing_rto); 542 void tcp_skb_collapse_tstamp(struct sk_buff *skb, 543 const struct sk_buff *next_skb); 544 545 /* tcp_input.c */ 546 void tcp_rearm_rto(struct sock *sk); 547 void tcp_synack_rtt_meas(struct sock *sk, struct request_sock *req); 548 void tcp_reset(struct sock *sk); 549 void tcp_skb_mark_lost_uncond_verify(struct tcp_sock *tp, struct sk_buff *skb); 550 void tcp_fin(struct sock *sk); 551 552 /* tcp_timer.c */ 553 void tcp_init_xmit_timers(struct sock *); 554 static inline void tcp_clear_xmit_timers(struct sock *sk) 555 { 556 hrtimer_cancel(&tcp_sk(sk)->pacing_timer); 557 inet_csk_clear_xmit_timers(sk); 558 } 559 560 unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu); 561 unsigned int tcp_current_mss(struct sock *sk); 562 563 /* Bound MSS / TSO packet size with the half of the window */ 564 static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize) 565 { 566 int cutoff; 567 568 /* When peer uses tiny windows, there is no use in packetizing 569 * to sub-MSS pieces for the sake of SWS or making sure there 570 * are enough packets in the pipe for fast recovery. 571 * 572 * On the other hand, for extremely large MSS devices, handling 573 * smaller than MSS windows in this way does make sense. 574 */ 575 if (tp->max_window > TCP_MSS_DEFAULT) 576 cutoff = (tp->max_window >> 1); 577 else 578 cutoff = tp->max_window; 579 580 if (cutoff && pktsize > cutoff) 581 return max_t(int, cutoff, 68U - tp->tcp_header_len); 582 else 583 return pktsize; 584 } 585 586 /* tcp.c */ 587 void tcp_get_info(struct sock *, struct tcp_info *); 588 589 /* Read 'sendfile()'-style from a TCP socket */ 590 int tcp_read_sock(struct sock *sk, read_descriptor_t *desc, 591 sk_read_actor_t recv_actor); 592 593 void tcp_initialize_rcv_mss(struct sock *sk); 594 595 int tcp_mtu_to_mss(struct sock *sk, int pmtu); 596 int tcp_mss_to_mtu(struct sock *sk, int mss); 597 void tcp_mtup_init(struct sock *sk); 598 void tcp_init_buffer_space(struct sock *sk); 599 600 static inline void tcp_bound_rto(const struct sock *sk) 601 { 602 if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX) 603 inet_csk(sk)->icsk_rto = TCP_RTO_MAX; 604 } 605 606 static inline u32 __tcp_set_rto(const struct tcp_sock *tp) 607 { 608 return usecs_to_jiffies((tp->srtt_us >> 3) + tp->rttvar_us); 609 } 610 611 static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd) 612 { 613 tp->pred_flags = htonl((tp->tcp_header_len << 26) | 614 ntohl(TCP_FLAG_ACK) | 615 snd_wnd); 616 } 617 618 static inline void tcp_fast_path_on(struct tcp_sock *tp) 619 { 620 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale); 621 } 622 623 static inline void tcp_fast_path_check(struct sock *sk) 624 { 625 struct tcp_sock *tp = tcp_sk(sk); 626 627 if (RB_EMPTY_ROOT(&tp->out_of_order_queue) && 628 tp->rcv_wnd && 629 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf && 630 !tp->urg_data) 631 tcp_fast_path_on(tp); 632 } 633 634 /* Compute the actual rto_min value */ 635 static inline u32 tcp_rto_min(struct sock *sk) 636 { 637 const struct dst_entry *dst = __sk_dst_get(sk); 638 u32 rto_min = TCP_RTO_MIN; 639 640 if (dst && dst_metric_locked(dst, RTAX_RTO_MIN)) 641 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN); 642 return rto_min; 643 } 644 645 static inline u32 tcp_rto_min_us(struct sock *sk) 646 { 647 return jiffies_to_usecs(tcp_rto_min(sk)); 648 } 649 650 static inline bool tcp_ca_dst_locked(const struct dst_entry *dst) 651 { 652 return dst_metric_locked(dst, RTAX_CC_ALGO); 653 } 654 655 /* Minimum RTT in usec. ~0 means not available. */ 656 static inline u32 tcp_min_rtt(const struct tcp_sock *tp) 657 { 658 return minmax_get(&tp->rtt_min); 659 } 660 661 /* Compute the actual receive window we are currently advertising. 662 * Rcv_nxt can be after the window if our peer push more data 663 * than the offered window. 664 */ 665 static inline u32 tcp_receive_window(const struct tcp_sock *tp) 666 { 667 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt; 668 669 if (win < 0) 670 win = 0; 671 return (u32) win; 672 } 673 674 /* Choose a new window, without checks for shrinking, and without 675 * scaling applied to the result. The caller does these things 676 * if necessary. This is a "raw" window selection. 677 */ 678 u32 __tcp_select_window(struct sock *sk); 679 680 void tcp_send_window_probe(struct sock *sk); 681 682 /* TCP uses 32bit jiffies to save some space. 683 * Note that this is different from tcp_time_stamp, which 684 * historically has been the same until linux-4.13. 685 */ 686 #define tcp_jiffies32 ((u32)jiffies) 687 688 /* 689 * Deliver a 32bit value for TCP timestamp option (RFC 7323) 690 * It is no longer tied to jiffies, but to 1 ms clock. 691 * Note: double check if you want to use tcp_jiffies32 instead of this. 692 */ 693 #define TCP_TS_HZ 1000 694 695 static inline u64 tcp_clock_ns(void) 696 { 697 return local_clock(); 698 } 699 700 static inline u64 tcp_clock_us(void) 701 { 702 return div_u64(tcp_clock_ns(), NSEC_PER_USEC); 703 } 704 705 /* This should only be used in contexts where tp->tcp_mstamp is up to date */ 706 static inline u32 tcp_time_stamp(const struct tcp_sock *tp) 707 { 708 return div_u64(tp->tcp_mstamp, USEC_PER_SEC / TCP_TS_HZ); 709 } 710 711 /* Could use tcp_clock_us() / 1000, but this version uses a single divide */ 712 static inline u32 tcp_time_stamp_raw(void) 713 { 714 return div_u64(tcp_clock_ns(), NSEC_PER_SEC / TCP_TS_HZ); 715 } 716 717 718 /* Refresh 1us clock of a TCP socket, 719 * ensuring monotically increasing values. 720 */ 721 static inline void tcp_mstamp_refresh(struct tcp_sock *tp) 722 { 723 u64 val = tcp_clock_us(); 724 725 if (val > tp->tcp_mstamp) 726 tp->tcp_mstamp = val; 727 } 728 729 static inline u32 tcp_stamp_us_delta(u64 t1, u64 t0) 730 { 731 return max_t(s64, t1 - t0, 0); 732 } 733 734 static inline u32 tcp_skb_timestamp(const struct sk_buff *skb) 735 { 736 return div_u64(skb->skb_mstamp, USEC_PER_SEC / TCP_TS_HZ); 737 } 738 739 740 #define tcp_flag_byte(th) (((u_int8_t *)th)[13]) 741 742 #define TCPHDR_FIN 0x01 743 #define TCPHDR_SYN 0x02 744 #define TCPHDR_RST 0x04 745 #define TCPHDR_PSH 0x08 746 #define TCPHDR_ACK 0x10 747 #define TCPHDR_URG 0x20 748 #define TCPHDR_ECE 0x40 749 #define TCPHDR_CWR 0x80 750 751 #define TCPHDR_SYN_ECN (TCPHDR_SYN | TCPHDR_ECE | TCPHDR_CWR) 752 753 /* This is what the send packet queuing engine uses to pass 754 * TCP per-packet control information to the transmission code. 755 * We also store the host-order sequence numbers in here too. 756 * This is 44 bytes if IPV6 is enabled. 757 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately. 758 */ 759 struct tcp_skb_cb { 760 __u32 seq; /* Starting sequence number */ 761 __u32 end_seq; /* SEQ + FIN + SYN + datalen */ 762 union { 763 /* Note : tcp_tw_isn is used in input path only 764 * (isn chosen by tcp_timewait_state_process()) 765 * 766 * tcp_gso_segs/size are used in write queue only, 767 * cf tcp_skb_pcount()/tcp_skb_mss() 768 */ 769 __u32 tcp_tw_isn; 770 struct { 771 u16 tcp_gso_segs; 772 u16 tcp_gso_size; 773 }; 774 }; 775 __u8 tcp_flags; /* TCP header flags. (tcp[13]) */ 776 777 __u8 sacked; /* State flags for SACK. */ 778 #define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */ 779 #define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */ 780 #define TCPCB_LOST 0x04 /* SKB is lost */ 781 #define TCPCB_TAGBITS 0x07 /* All tag bits */ 782 #define TCPCB_REPAIRED 0x10 /* SKB repaired (no skb_mstamp) */ 783 #define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */ 784 #define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS| \ 785 TCPCB_REPAIRED) 786 787 __u8 ip_dsfield; /* IPv4 tos or IPv6 dsfield */ 788 __u8 txstamp_ack:1, /* Record TX timestamp for ack? */ 789 eor:1, /* Is skb MSG_EOR marked? */ 790 has_rxtstamp:1, /* SKB has a RX timestamp */ 791 unused:5; 792 __u32 ack_seq; /* Sequence number ACK'd */ 793 union { 794 struct { 795 /* There is space for up to 24 bytes */ 796 __u32 in_flight:30,/* Bytes in flight at transmit */ 797 is_app_limited:1, /* cwnd not fully used? */ 798 unused:1; 799 /* pkts S/ACKed so far upon tx of skb, incl retrans: */ 800 __u32 delivered; 801 /* start of send pipeline phase */ 802 u64 first_tx_mstamp; 803 /* when we reached the "delivered" count */ 804 u64 delivered_mstamp; 805 } tx; /* only used for outgoing skbs */ 806 union { 807 struct inet_skb_parm h4; 808 #if IS_ENABLED(CONFIG_IPV6) 809 struct inet6_skb_parm h6; 810 #endif 811 } header; /* For incoming skbs */ 812 struct { 813 __u32 key; 814 __u32 flags; 815 struct bpf_map *map; 816 void *data_end; 817 } bpf; 818 }; 819 }; 820 821 #define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0])) 822 823 824 #if IS_ENABLED(CONFIG_IPV6) 825 /* This is the variant of inet6_iif() that must be used by TCP, 826 * as TCP moves IP6CB into a different location in skb->cb[] 827 */ 828 static inline int tcp_v6_iif(const struct sk_buff *skb) 829 { 830 bool l3_slave = ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags); 831 832 return l3_slave ? skb->skb_iif : TCP_SKB_CB(skb)->header.h6.iif; 833 } 834 835 /* TCP_SKB_CB reference means this can not be used from early demux */ 836 static inline int tcp_v6_sdif(const struct sk_buff *skb) 837 { 838 #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV) 839 if (skb && ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags)) 840 return TCP_SKB_CB(skb)->header.h6.iif; 841 #endif 842 return 0; 843 } 844 #endif 845 846 static inline bool inet_exact_dif_match(struct net *net, struct sk_buff *skb) 847 { 848 #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV) 849 if (!net->ipv4.sysctl_tcp_l3mdev_accept && 850 skb && ipv4_l3mdev_skb(IPCB(skb)->flags)) 851 return true; 852 #endif 853 return false; 854 } 855 856 /* TCP_SKB_CB reference means this can not be used from early demux */ 857 static inline int tcp_v4_sdif(struct sk_buff *skb) 858 { 859 #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV) 860 if (skb && ipv4_l3mdev_skb(TCP_SKB_CB(skb)->header.h4.flags)) 861 return TCP_SKB_CB(skb)->header.h4.iif; 862 #endif 863 return 0; 864 } 865 866 /* Due to TSO, an SKB can be composed of multiple actual 867 * packets. To keep these tracked properly, we use this. 868 */ 869 static inline int tcp_skb_pcount(const struct sk_buff *skb) 870 { 871 return TCP_SKB_CB(skb)->tcp_gso_segs; 872 } 873 874 static inline void tcp_skb_pcount_set(struct sk_buff *skb, int segs) 875 { 876 TCP_SKB_CB(skb)->tcp_gso_segs = segs; 877 } 878 879 static inline void tcp_skb_pcount_add(struct sk_buff *skb, int segs) 880 { 881 TCP_SKB_CB(skb)->tcp_gso_segs += segs; 882 } 883 884 /* This is valid iff skb is in write queue and tcp_skb_pcount() > 1. */ 885 static inline int tcp_skb_mss(const struct sk_buff *skb) 886 { 887 return TCP_SKB_CB(skb)->tcp_gso_size; 888 } 889 890 static inline bool tcp_skb_can_collapse_to(const struct sk_buff *skb) 891 { 892 return likely(!TCP_SKB_CB(skb)->eor); 893 } 894 895 /* Events passed to congestion control interface */ 896 enum tcp_ca_event { 897 CA_EVENT_TX_START, /* first transmit when no packets in flight */ 898 CA_EVENT_CWND_RESTART, /* congestion window restart */ 899 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */ 900 CA_EVENT_LOSS, /* loss timeout */ 901 CA_EVENT_ECN_NO_CE, /* ECT set, but not CE marked */ 902 CA_EVENT_ECN_IS_CE, /* received CE marked IP packet */ 903 CA_EVENT_DELAYED_ACK, /* Delayed ack is sent */ 904 CA_EVENT_NON_DELAYED_ACK, 905 }; 906 907 /* Information about inbound ACK, passed to cong_ops->in_ack_event() */ 908 enum tcp_ca_ack_event_flags { 909 CA_ACK_SLOWPATH = (1 << 0), /* In slow path processing */ 910 CA_ACK_WIN_UPDATE = (1 << 1), /* ACK updated window */ 911 CA_ACK_ECE = (1 << 2), /* ECE bit is set on ack */ 912 }; 913 914 /* 915 * Interface for adding new TCP congestion control handlers 916 */ 917 #define TCP_CA_NAME_MAX 16 918 #define TCP_CA_MAX 128 919 #define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX) 920 921 #define TCP_CA_UNSPEC 0 922 923 /* Algorithm can be set on socket without CAP_NET_ADMIN privileges */ 924 #define TCP_CONG_NON_RESTRICTED 0x1 925 /* Requires ECN/ECT set on all packets */ 926 #define TCP_CONG_NEEDS_ECN 0x2 927 928 union tcp_cc_info; 929 930 struct ack_sample { 931 u32 pkts_acked; 932 s32 rtt_us; 933 u32 in_flight; 934 }; 935 936 /* A rate sample measures the number of (original/retransmitted) data 937 * packets delivered "delivered" over an interval of time "interval_us". 938 * The tcp_rate.c code fills in the rate sample, and congestion 939 * control modules that define a cong_control function to run at the end 940 * of ACK processing can optionally chose to consult this sample when 941 * setting cwnd and pacing rate. 942 * A sample is invalid if "delivered" or "interval_us" is negative. 943 */ 944 struct rate_sample { 945 u64 prior_mstamp; /* starting timestamp for interval */ 946 u32 prior_delivered; /* tp->delivered at "prior_mstamp" */ 947 s32 delivered; /* number of packets delivered over interval */ 948 long interval_us; /* time for tp->delivered to incr "delivered" */ 949 long rtt_us; /* RTT of last (S)ACKed packet (or -1) */ 950 int losses; /* number of packets marked lost upon ACK */ 951 u32 acked_sacked; /* number of packets newly (S)ACKed upon ACK */ 952 u32 prior_in_flight; /* in flight before this ACK */ 953 bool is_app_limited; /* is sample from packet with bubble in pipe? */ 954 bool is_retrans; /* is sample from retransmission? */ 955 bool is_ack_delayed; /* is this (likely) a delayed ACK? */ 956 }; 957 958 struct tcp_congestion_ops { 959 struct list_head list; 960 u32 key; 961 u32 flags; 962 963 /* initialize private data (optional) */ 964 void (*init)(struct sock *sk); 965 /* cleanup private data (optional) */ 966 void (*release)(struct sock *sk); 967 968 /* return slow start threshold (required) */ 969 u32 (*ssthresh)(struct sock *sk); 970 /* do new cwnd calculation (required) */ 971 void (*cong_avoid)(struct sock *sk, u32 ack, u32 acked); 972 /* call before changing ca_state (optional) */ 973 void (*set_state)(struct sock *sk, u8 new_state); 974 /* call when cwnd event occurs (optional) */ 975 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev); 976 /* call when ack arrives (optional) */ 977 void (*in_ack_event)(struct sock *sk, u32 flags); 978 /* new value of cwnd after loss (required) */ 979 u32 (*undo_cwnd)(struct sock *sk); 980 /* hook for packet ack accounting (optional) */ 981 void (*pkts_acked)(struct sock *sk, const struct ack_sample *sample); 982 /* override sysctl_tcp_min_tso_segs */ 983 u32 (*min_tso_segs)(struct sock *sk); 984 /* returns the multiplier used in tcp_sndbuf_expand (optional) */ 985 u32 (*sndbuf_expand)(struct sock *sk); 986 /* call when packets are delivered to update cwnd and pacing rate, 987 * after all the ca_state processing. (optional) 988 */ 989 void (*cong_control)(struct sock *sk, const struct rate_sample *rs); 990 /* get info for inet_diag (optional) */ 991 size_t (*get_info)(struct sock *sk, u32 ext, int *attr, 992 union tcp_cc_info *info); 993 994 char name[TCP_CA_NAME_MAX]; 995 struct module *owner; 996 }; 997 998 int tcp_register_congestion_control(struct tcp_congestion_ops *type); 999 void tcp_unregister_congestion_control(struct tcp_congestion_ops *type); 1000 1001 void tcp_assign_congestion_control(struct sock *sk); 1002 void tcp_init_congestion_control(struct sock *sk); 1003 void tcp_cleanup_congestion_control(struct sock *sk); 1004 int tcp_set_default_congestion_control(struct net *net, const char *name); 1005 void tcp_get_default_congestion_control(struct net *net, char *name); 1006 void tcp_get_available_congestion_control(char *buf, size_t len); 1007 void tcp_get_allowed_congestion_control(char *buf, size_t len); 1008 int tcp_set_allowed_congestion_control(char *allowed); 1009 int tcp_set_congestion_control(struct sock *sk, const char *name, bool load, bool reinit); 1010 u32 tcp_slow_start(struct tcp_sock *tp, u32 acked); 1011 void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w, u32 acked); 1012 1013 u32 tcp_reno_ssthresh(struct sock *sk); 1014 u32 tcp_reno_undo_cwnd(struct sock *sk); 1015 void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 acked); 1016 extern struct tcp_congestion_ops tcp_reno; 1017 1018 struct tcp_congestion_ops *tcp_ca_find_key(u32 key); 1019 u32 tcp_ca_get_key_by_name(struct net *net, const char *name, bool *ecn_ca); 1020 #ifdef CONFIG_INET 1021 char *tcp_ca_get_name_by_key(u32 key, char *buffer); 1022 #else 1023 static inline char *tcp_ca_get_name_by_key(u32 key, char *buffer) 1024 { 1025 return NULL; 1026 } 1027 #endif 1028 1029 static inline bool tcp_ca_needs_ecn(const struct sock *sk) 1030 { 1031 const struct inet_connection_sock *icsk = inet_csk(sk); 1032 1033 return icsk->icsk_ca_ops->flags & TCP_CONG_NEEDS_ECN; 1034 } 1035 1036 static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state) 1037 { 1038 struct inet_connection_sock *icsk = inet_csk(sk); 1039 1040 if (icsk->icsk_ca_ops->set_state) 1041 icsk->icsk_ca_ops->set_state(sk, ca_state); 1042 icsk->icsk_ca_state = ca_state; 1043 } 1044 1045 static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event) 1046 { 1047 const struct inet_connection_sock *icsk = inet_csk(sk); 1048 1049 if (icsk->icsk_ca_ops->cwnd_event) 1050 icsk->icsk_ca_ops->cwnd_event(sk, event); 1051 } 1052 1053 /* From tcp_rate.c */ 1054 void tcp_rate_skb_sent(struct sock *sk, struct sk_buff *skb); 1055 void tcp_rate_skb_delivered(struct sock *sk, struct sk_buff *skb, 1056 struct rate_sample *rs); 1057 void tcp_rate_gen(struct sock *sk, u32 delivered, u32 lost, 1058 bool is_sack_reneg, struct rate_sample *rs); 1059 void tcp_rate_check_app_limited(struct sock *sk); 1060 1061 /* These functions determine how the current flow behaves in respect of SACK 1062 * handling. SACK is negotiated with the peer, and therefore it can vary 1063 * between different flows. 1064 * 1065 * tcp_is_sack - SACK enabled 1066 * tcp_is_reno - No SACK 1067 */ 1068 static inline int tcp_is_sack(const struct tcp_sock *tp) 1069 { 1070 return tp->rx_opt.sack_ok; 1071 } 1072 1073 static inline bool tcp_is_reno(const struct tcp_sock *tp) 1074 { 1075 return !tcp_is_sack(tp); 1076 } 1077 1078 static inline unsigned int tcp_left_out(const struct tcp_sock *tp) 1079 { 1080 return tp->sacked_out + tp->lost_out; 1081 } 1082 1083 /* This determines how many packets are "in the network" to the best 1084 * of our knowledge. In many cases it is conservative, but where 1085 * detailed information is available from the receiver (via SACK 1086 * blocks etc.) we can make more aggressive calculations. 1087 * 1088 * Use this for decisions involving congestion control, use just 1089 * tp->packets_out to determine if the send queue is empty or not. 1090 * 1091 * Read this equation as: 1092 * 1093 * "Packets sent once on transmission queue" MINUS 1094 * "Packets left network, but not honestly ACKed yet" PLUS 1095 * "Packets fast retransmitted" 1096 */ 1097 static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp) 1098 { 1099 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out; 1100 } 1101 1102 #define TCP_INFINITE_SSTHRESH 0x7fffffff 1103 1104 static inline bool tcp_in_slow_start(const struct tcp_sock *tp) 1105 { 1106 return tp->snd_cwnd < tp->snd_ssthresh; 1107 } 1108 1109 static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp) 1110 { 1111 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH; 1112 } 1113 1114 static inline bool tcp_in_cwnd_reduction(const struct sock *sk) 1115 { 1116 return (TCPF_CA_CWR | TCPF_CA_Recovery) & 1117 (1 << inet_csk(sk)->icsk_ca_state); 1118 } 1119 1120 /* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd. 1121 * The exception is cwnd reduction phase, when cwnd is decreasing towards 1122 * ssthresh. 1123 */ 1124 static inline __u32 tcp_current_ssthresh(const struct sock *sk) 1125 { 1126 const struct tcp_sock *tp = tcp_sk(sk); 1127 1128 if (tcp_in_cwnd_reduction(sk)) 1129 return tp->snd_ssthresh; 1130 else 1131 return max(tp->snd_ssthresh, 1132 ((tp->snd_cwnd >> 1) + 1133 (tp->snd_cwnd >> 2))); 1134 } 1135 1136 /* Use define here intentionally to get WARN_ON location shown at the caller */ 1137 #define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out) 1138 1139 void tcp_enter_cwr(struct sock *sk); 1140 __u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst); 1141 1142 /* The maximum number of MSS of available cwnd for which TSO defers 1143 * sending if not using sysctl_tcp_tso_win_divisor. 1144 */ 1145 static inline __u32 tcp_max_tso_deferred_mss(const struct tcp_sock *tp) 1146 { 1147 return 3; 1148 } 1149 1150 /* Returns end sequence number of the receiver's advertised window */ 1151 static inline u32 tcp_wnd_end(const struct tcp_sock *tp) 1152 { 1153 return tp->snd_una + tp->snd_wnd; 1154 } 1155 1156 /* We follow the spirit of RFC2861 to validate cwnd but implement a more 1157 * flexible approach. The RFC suggests cwnd should not be raised unless 1158 * it was fully used previously. And that's exactly what we do in 1159 * congestion avoidance mode. But in slow start we allow cwnd to grow 1160 * as long as the application has used half the cwnd. 1161 * Example : 1162 * cwnd is 10 (IW10), but application sends 9 frames. 1163 * We allow cwnd to reach 18 when all frames are ACKed. 1164 * This check is safe because it's as aggressive as slow start which already 1165 * risks 100% overshoot. The advantage is that we discourage application to 1166 * either send more filler packets or data to artificially blow up the cwnd 1167 * usage, and allow application-limited process to probe bw more aggressively. 1168 */ 1169 static inline bool tcp_is_cwnd_limited(const struct sock *sk) 1170 { 1171 const struct tcp_sock *tp = tcp_sk(sk); 1172 1173 /* If in slow start, ensure cwnd grows to twice what was ACKed. */ 1174 if (tcp_in_slow_start(tp)) 1175 return tp->snd_cwnd < 2 * tp->max_packets_out; 1176 1177 return tp->is_cwnd_limited; 1178 } 1179 1180 /* Something is really bad, we could not queue an additional packet, 1181 * because qdisc is full or receiver sent a 0 window. 1182 * We do not want to add fuel to the fire, or abort too early, 1183 * so make sure the timer we arm now is at least 200ms in the future, 1184 * regardless of current icsk_rto value (as it could be ~2ms) 1185 */ 1186 static inline unsigned long tcp_probe0_base(const struct sock *sk) 1187 { 1188 return max_t(unsigned long, inet_csk(sk)->icsk_rto, TCP_RTO_MIN); 1189 } 1190 1191 /* Variant of inet_csk_rto_backoff() used for zero window probes */ 1192 static inline unsigned long tcp_probe0_when(const struct sock *sk, 1193 unsigned long max_when) 1194 { 1195 u64 when = (u64)tcp_probe0_base(sk) << inet_csk(sk)->icsk_backoff; 1196 1197 return (unsigned long)min_t(u64, when, max_when); 1198 } 1199 1200 static inline void tcp_check_probe_timer(struct sock *sk) 1201 { 1202 if (!tcp_sk(sk)->packets_out && !inet_csk(sk)->icsk_pending) 1203 inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0, 1204 tcp_probe0_base(sk), TCP_RTO_MAX); 1205 } 1206 1207 static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq) 1208 { 1209 tp->snd_wl1 = seq; 1210 } 1211 1212 static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq) 1213 { 1214 tp->snd_wl1 = seq; 1215 } 1216 1217 /* 1218 * Calculate(/check) TCP checksum 1219 */ 1220 static inline __sum16 tcp_v4_check(int len, __be32 saddr, 1221 __be32 daddr, __wsum base) 1222 { 1223 return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base); 1224 } 1225 1226 static inline __sum16 __tcp_checksum_complete(struct sk_buff *skb) 1227 { 1228 return __skb_checksum_complete(skb); 1229 } 1230 1231 static inline bool tcp_checksum_complete(struct sk_buff *skb) 1232 { 1233 return !skb_csum_unnecessary(skb) && 1234 __tcp_checksum_complete(skb); 1235 } 1236 1237 bool tcp_add_backlog(struct sock *sk, struct sk_buff *skb); 1238 int tcp_filter(struct sock *sk, struct sk_buff *skb); 1239 1240 #undef STATE_TRACE 1241 1242 #ifdef STATE_TRACE 1243 static const char *statename[]={ 1244 "Unused","Established","Syn Sent","Syn Recv", 1245 "Fin Wait 1","Fin Wait 2","Time Wait", "Close", 1246 "Close Wait","Last ACK","Listen","Closing" 1247 }; 1248 #endif 1249 void tcp_set_state(struct sock *sk, int state); 1250 1251 void tcp_done(struct sock *sk); 1252 1253 int tcp_abort(struct sock *sk, int err); 1254 1255 static inline void tcp_sack_reset(struct tcp_options_received *rx_opt) 1256 { 1257 rx_opt->dsack = 0; 1258 rx_opt->num_sacks = 0; 1259 } 1260 1261 u32 tcp_default_init_rwnd(u32 mss); 1262 void tcp_cwnd_restart(struct sock *sk, s32 delta); 1263 1264 static inline void tcp_slow_start_after_idle_check(struct sock *sk) 1265 { 1266 const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops; 1267 struct tcp_sock *tp = tcp_sk(sk); 1268 s32 delta; 1269 1270 if (!sock_net(sk)->ipv4.sysctl_tcp_slow_start_after_idle || tp->packets_out || 1271 ca_ops->cong_control) 1272 return; 1273 delta = tcp_jiffies32 - tp->lsndtime; 1274 if (delta > inet_csk(sk)->icsk_rto) 1275 tcp_cwnd_restart(sk, delta); 1276 } 1277 1278 /* Determine a window scaling and initial window to offer. */ 1279 void tcp_select_initial_window(const struct sock *sk, int __space, 1280 __u32 mss, __u32 *rcv_wnd, 1281 __u32 *window_clamp, int wscale_ok, 1282 __u8 *rcv_wscale, __u32 init_rcv_wnd); 1283 1284 static inline int tcp_win_from_space(const struct sock *sk, int space) 1285 { 1286 int tcp_adv_win_scale = sock_net(sk)->ipv4.sysctl_tcp_adv_win_scale; 1287 1288 return tcp_adv_win_scale <= 0 ? 1289 (space>>(-tcp_adv_win_scale)) : 1290 space - (space>>tcp_adv_win_scale); 1291 } 1292 1293 /* Note: caller must be prepared to deal with negative returns */ 1294 static inline int tcp_space(const struct sock *sk) 1295 { 1296 return tcp_win_from_space(sk, sk->sk_rcvbuf - 1297 atomic_read(&sk->sk_rmem_alloc)); 1298 } 1299 1300 static inline int tcp_full_space(const struct sock *sk) 1301 { 1302 return tcp_win_from_space(sk, sk->sk_rcvbuf); 1303 } 1304 1305 extern void tcp_openreq_init_rwin(struct request_sock *req, 1306 const struct sock *sk_listener, 1307 const struct dst_entry *dst); 1308 1309 void tcp_enter_memory_pressure(struct sock *sk); 1310 void tcp_leave_memory_pressure(struct sock *sk); 1311 1312 static inline int keepalive_intvl_when(const struct tcp_sock *tp) 1313 { 1314 struct net *net = sock_net((struct sock *)tp); 1315 1316 return tp->keepalive_intvl ? : net->ipv4.sysctl_tcp_keepalive_intvl; 1317 } 1318 1319 static inline int keepalive_time_when(const struct tcp_sock *tp) 1320 { 1321 struct net *net = sock_net((struct sock *)tp); 1322 1323 return tp->keepalive_time ? : net->ipv4.sysctl_tcp_keepalive_time; 1324 } 1325 1326 static inline int keepalive_probes(const struct tcp_sock *tp) 1327 { 1328 struct net *net = sock_net((struct sock *)tp); 1329 1330 return tp->keepalive_probes ? : net->ipv4.sysctl_tcp_keepalive_probes; 1331 } 1332 1333 static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp) 1334 { 1335 const struct inet_connection_sock *icsk = &tp->inet_conn; 1336 1337 return min_t(u32, tcp_jiffies32 - icsk->icsk_ack.lrcvtime, 1338 tcp_jiffies32 - tp->rcv_tstamp); 1339 } 1340 1341 static inline int tcp_fin_time(const struct sock *sk) 1342 { 1343 int fin_timeout = tcp_sk(sk)->linger2 ? : sock_net(sk)->ipv4.sysctl_tcp_fin_timeout; 1344 const int rto = inet_csk(sk)->icsk_rto; 1345 1346 if (fin_timeout < (rto << 2) - (rto >> 1)) 1347 fin_timeout = (rto << 2) - (rto >> 1); 1348 1349 return fin_timeout; 1350 } 1351 1352 static inline bool tcp_paws_check(const struct tcp_options_received *rx_opt, 1353 int paws_win) 1354 { 1355 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win) 1356 return true; 1357 if (unlikely(get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS)) 1358 return true; 1359 /* 1360 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0, 1361 * then following tcp messages have valid values. Ignore 0 value, 1362 * or else 'negative' tsval might forbid us to accept their packets. 1363 */ 1364 if (!rx_opt->ts_recent) 1365 return true; 1366 return false; 1367 } 1368 1369 static inline bool tcp_paws_reject(const struct tcp_options_received *rx_opt, 1370 int rst) 1371 { 1372 if (tcp_paws_check(rx_opt, 0)) 1373 return false; 1374 1375 /* RST segments are not recommended to carry timestamp, 1376 and, if they do, it is recommended to ignore PAWS because 1377 "their cleanup function should take precedence over timestamps." 1378 Certainly, it is mistake. It is necessary to understand the reasons 1379 of this constraint to relax it: if peer reboots, clock may go 1380 out-of-sync and half-open connections will not be reset. 1381 Actually, the problem would be not existing if all 1382 the implementations followed draft about maintaining clock 1383 via reboots. Linux-2.2 DOES NOT! 1384 1385 However, we can relax time bounds for RST segments to MSL. 1386 */ 1387 if (rst && get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_MSL) 1388 return false; 1389 return true; 1390 } 1391 1392 bool tcp_oow_rate_limited(struct net *net, const struct sk_buff *skb, 1393 int mib_idx, u32 *last_oow_ack_time); 1394 1395 static inline void tcp_mib_init(struct net *net) 1396 { 1397 /* See RFC 2012 */ 1398 TCP_ADD_STATS(net, TCP_MIB_RTOALGORITHM, 1); 1399 TCP_ADD_STATS(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ); 1400 TCP_ADD_STATS(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ); 1401 TCP_ADD_STATS(net, TCP_MIB_MAXCONN, -1); 1402 } 1403 1404 /* from STCP */ 1405 static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp) 1406 { 1407 tp->lost_skb_hint = NULL; 1408 } 1409 1410 static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp) 1411 { 1412 tcp_clear_retrans_hints_partial(tp); 1413 tp->retransmit_skb_hint = NULL; 1414 } 1415 1416 union tcp_md5_addr { 1417 struct in_addr a4; 1418 #if IS_ENABLED(CONFIG_IPV6) 1419 struct in6_addr a6; 1420 #endif 1421 }; 1422 1423 /* - key database */ 1424 struct tcp_md5sig_key { 1425 struct hlist_node node; 1426 u8 keylen; 1427 u8 family; /* AF_INET or AF_INET6 */ 1428 union tcp_md5_addr addr; 1429 u8 prefixlen; 1430 u8 key[TCP_MD5SIG_MAXKEYLEN]; 1431 struct rcu_head rcu; 1432 }; 1433 1434 /* - sock block */ 1435 struct tcp_md5sig_info { 1436 struct hlist_head head; 1437 struct rcu_head rcu; 1438 }; 1439 1440 /* - pseudo header */ 1441 struct tcp4_pseudohdr { 1442 __be32 saddr; 1443 __be32 daddr; 1444 __u8 pad; 1445 __u8 protocol; 1446 __be16 len; 1447 }; 1448 1449 struct tcp6_pseudohdr { 1450 struct in6_addr saddr; 1451 struct in6_addr daddr; 1452 __be32 len; 1453 __be32 protocol; /* including padding */ 1454 }; 1455 1456 union tcp_md5sum_block { 1457 struct tcp4_pseudohdr ip4; 1458 #if IS_ENABLED(CONFIG_IPV6) 1459 struct tcp6_pseudohdr ip6; 1460 #endif 1461 }; 1462 1463 /* - pool: digest algorithm, hash description and scratch buffer */ 1464 struct tcp_md5sig_pool { 1465 struct ahash_request *md5_req; 1466 void *scratch; 1467 }; 1468 1469 /* - functions */ 1470 int tcp_v4_md5_hash_skb(char *md5_hash, const struct tcp_md5sig_key *key, 1471 const struct sock *sk, const struct sk_buff *skb); 1472 int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr, 1473 int family, u8 prefixlen, const u8 *newkey, u8 newkeylen, 1474 gfp_t gfp); 1475 int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr, 1476 int family, u8 prefixlen); 1477 struct tcp_md5sig_key *tcp_v4_md5_lookup(const struct sock *sk, 1478 const struct sock *addr_sk); 1479 1480 #ifdef CONFIG_TCP_MD5SIG 1481 struct tcp_md5sig_key *tcp_md5_do_lookup(const struct sock *sk, 1482 const union tcp_md5_addr *addr, 1483 int family); 1484 #define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key) 1485 #else 1486 static inline struct tcp_md5sig_key *tcp_md5_do_lookup(const struct sock *sk, 1487 const union tcp_md5_addr *addr, 1488 int family) 1489 { 1490 return NULL; 1491 } 1492 #define tcp_twsk_md5_key(twsk) NULL 1493 #endif 1494 1495 bool tcp_alloc_md5sig_pool(void); 1496 1497 struct tcp_md5sig_pool *tcp_get_md5sig_pool(void); 1498 static inline void tcp_put_md5sig_pool(void) 1499 { 1500 local_bh_enable(); 1501 } 1502 1503 int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *, 1504 unsigned int header_len); 1505 int tcp_md5_hash_key(struct tcp_md5sig_pool *hp, 1506 const struct tcp_md5sig_key *key); 1507 1508 /* From tcp_fastopen.c */ 1509 void tcp_fastopen_cache_get(struct sock *sk, u16 *mss, 1510 struct tcp_fastopen_cookie *cookie); 1511 void tcp_fastopen_cache_set(struct sock *sk, u16 mss, 1512 struct tcp_fastopen_cookie *cookie, bool syn_lost, 1513 u16 try_exp); 1514 struct tcp_fastopen_request { 1515 /* Fast Open cookie. Size 0 means a cookie request */ 1516 struct tcp_fastopen_cookie cookie; 1517 struct msghdr *data; /* data in MSG_FASTOPEN */ 1518 size_t size; 1519 int copied; /* queued in tcp_connect() */ 1520 }; 1521 void tcp_free_fastopen_req(struct tcp_sock *tp); 1522 void tcp_fastopen_destroy_cipher(struct sock *sk); 1523 void tcp_fastopen_ctx_destroy(struct net *net); 1524 int tcp_fastopen_reset_cipher(struct net *net, struct sock *sk, 1525 void *key, unsigned int len); 1526 void tcp_fastopen_add_skb(struct sock *sk, struct sk_buff *skb); 1527 struct sock *tcp_try_fastopen(struct sock *sk, struct sk_buff *skb, 1528 struct request_sock *req, 1529 struct tcp_fastopen_cookie *foc, 1530 const struct dst_entry *dst); 1531 void tcp_fastopen_init_key_once(struct net *net); 1532 bool tcp_fastopen_cookie_check(struct sock *sk, u16 *mss, 1533 struct tcp_fastopen_cookie *cookie); 1534 bool tcp_fastopen_defer_connect(struct sock *sk, int *err); 1535 #define TCP_FASTOPEN_KEY_LENGTH 16 1536 1537 /* Fastopen key context */ 1538 struct tcp_fastopen_context { 1539 struct crypto_cipher *tfm; 1540 __u8 key[TCP_FASTOPEN_KEY_LENGTH]; 1541 struct rcu_head rcu; 1542 }; 1543 1544 extern unsigned int sysctl_tcp_fastopen_blackhole_timeout; 1545 void tcp_fastopen_active_disable(struct sock *sk); 1546 bool tcp_fastopen_active_should_disable(struct sock *sk); 1547 void tcp_fastopen_active_disable_ofo_check(struct sock *sk); 1548 void tcp_fastopen_active_detect_blackhole(struct sock *sk, bool expired); 1549 1550 /* Latencies incurred by various limits for a sender. They are 1551 * chronograph-like stats that are mutually exclusive. 1552 */ 1553 enum tcp_chrono { 1554 TCP_CHRONO_UNSPEC, 1555 TCP_CHRONO_BUSY, /* Actively sending data (non-empty write queue) */ 1556 TCP_CHRONO_RWND_LIMITED, /* Stalled by insufficient receive window */ 1557 TCP_CHRONO_SNDBUF_LIMITED, /* Stalled by insufficient send buffer */ 1558 __TCP_CHRONO_MAX, 1559 }; 1560 1561 void tcp_chrono_start(struct sock *sk, const enum tcp_chrono type); 1562 void tcp_chrono_stop(struct sock *sk, const enum tcp_chrono type); 1563 1564 /* This helper is needed, because skb->tcp_tsorted_anchor uses 1565 * the same memory storage than skb->destructor/_skb_refdst 1566 */ 1567 static inline void tcp_skb_tsorted_anchor_cleanup(struct sk_buff *skb) 1568 { 1569 skb->destructor = NULL; 1570 skb->_skb_refdst = 0UL; 1571 } 1572 1573 #define tcp_skb_tsorted_save(skb) { \ 1574 unsigned long _save = skb->_skb_refdst; \ 1575 skb->_skb_refdst = 0UL; 1576 1577 #define tcp_skb_tsorted_restore(skb) \ 1578 skb->_skb_refdst = _save; \ 1579 } 1580 1581 void tcp_write_queue_purge(struct sock *sk); 1582 1583 static inline struct sk_buff *tcp_rtx_queue_head(const struct sock *sk) 1584 { 1585 return skb_rb_first(&sk->tcp_rtx_queue); 1586 } 1587 1588 static inline struct sk_buff *tcp_write_queue_head(const struct sock *sk) 1589 { 1590 return skb_peek(&sk->sk_write_queue); 1591 } 1592 1593 static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk) 1594 { 1595 return skb_peek_tail(&sk->sk_write_queue); 1596 } 1597 1598 #define tcp_for_write_queue_from_safe(skb, tmp, sk) \ 1599 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp) 1600 1601 static inline struct sk_buff *tcp_send_head(const struct sock *sk) 1602 { 1603 return skb_peek(&sk->sk_write_queue); 1604 } 1605 1606 static inline bool tcp_skb_is_last(const struct sock *sk, 1607 const struct sk_buff *skb) 1608 { 1609 return skb_queue_is_last(&sk->sk_write_queue, skb); 1610 } 1611 1612 static inline bool tcp_write_queue_empty(const struct sock *sk) 1613 { 1614 return skb_queue_empty(&sk->sk_write_queue); 1615 } 1616 1617 static inline bool tcp_rtx_queue_empty(const struct sock *sk) 1618 { 1619 return RB_EMPTY_ROOT(&sk->tcp_rtx_queue); 1620 } 1621 1622 static inline bool tcp_rtx_and_write_queues_empty(const struct sock *sk) 1623 { 1624 return tcp_rtx_queue_empty(sk) && tcp_write_queue_empty(sk); 1625 } 1626 1627 static inline void tcp_check_send_head(struct sock *sk, struct sk_buff *skb_unlinked) 1628 { 1629 if (tcp_write_queue_empty(sk)) 1630 tcp_chrono_stop(sk, TCP_CHRONO_BUSY); 1631 } 1632 1633 static inline void __tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb) 1634 { 1635 __skb_queue_tail(&sk->sk_write_queue, skb); 1636 } 1637 1638 static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb) 1639 { 1640 __tcp_add_write_queue_tail(sk, skb); 1641 1642 /* Queue it, remembering where we must start sending. */ 1643 if (sk->sk_write_queue.next == skb) 1644 tcp_chrono_start(sk, TCP_CHRONO_BUSY); 1645 } 1646 1647 /* Insert new before skb on the write queue of sk. */ 1648 static inline void tcp_insert_write_queue_before(struct sk_buff *new, 1649 struct sk_buff *skb, 1650 struct sock *sk) 1651 { 1652 __skb_queue_before(&sk->sk_write_queue, skb, new); 1653 } 1654 1655 static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk) 1656 { 1657 tcp_skb_tsorted_anchor_cleanup(skb); 1658 __skb_unlink(skb, &sk->sk_write_queue); 1659 } 1660 1661 void tcp_rbtree_insert(struct rb_root *root, struct sk_buff *skb); 1662 1663 static inline void tcp_rtx_queue_unlink(struct sk_buff *skb, struct sock *sk) 1664 { 1665 tcp_skb_tsorted_anchor_cleanup(skb); 1666 rb_erase(&skb->rbnode, &sk->tcp_rtx_queue); 1667 } 1668 1669 static inline void tcp_rtx_queue_unlink_and_free(struct sk_buff *skb, struct sock *sk) 1670 { 1671 list_del(&skb->tcp_tsorted_anchor); 1672 tcp_rtx_queue_unlink(skb, sk); 1673 sk_wmem_free_skb(sk, skb); 1674 } 1675 1676 static inline void tcp_push_pending_frames(struct sock *sk) 1677 { 1678 if (tcp_send_head(sk)) { 1679 struct tcp_sock *tp = tcp_sk(sk); 1680 1681 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle); 1682 } 1683 } 1684 1685 /* Start sequence of the skb just after the highest skb with SACKed 1686 * bit, valid only if sacked_out > 0 or when the caller has ensured 1687 * validity by itself. 1688 */ 1689 static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp) 1690 { 1691 if (!tp->sacked_out) 1692 return tp->snd_una; 1693 1694 if (tp->highest_sack == NULL) 1695 return tp->snd_nxt; 1696 1697 return TCP_SKB_CB(tp->highest_sack)->seq; 1698 } 1699 1700 static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb) 1701 { 1702 tcp_sk(sk)->highest_sack = skb_rb_next(skb); 1703 } 1704 1705 static inline struct sk_buff *tcp_highest_sack(struct sock *sk) 1706 { 1707 return tcp_sk(sk)->highest_sack; 1708 } 1709 1710 static inline void tcp_highest_sack_reset(struct sock *sk) 1711 { 1712 tcp_sk(sk)->highest_sack = tcp_rtx_queue_head(sk); 1713 } 1714 1715 /* Called when old skb is about to be deleted and replaced by new skb */ 1716 static inline void tcp_highest_sack_replace(struct sock *sk, 1717 struct sk_buff *old, 1718 struct sk_buff *new) 1719 { 1720 if (old == tcp_highest_sack(sk)) 1721 tcp_sk(sk)->highest_sack = new; 1722 } 1723 1724 /* This helper checks if socket has IP_TRANSPARENT set */ 1725 static inline bool inet_sk_transparent(const struct sock *sk) 1726 { 1727 switch (sk->sk_state) { 1728 case TCP_TIME_WAIT: 1729 return inet_twsk(sk)->tw_transparent; 1730 case TCP_NEW_SYN_RECV: 1731 return inet_rsk(inet_reqsk(sk))->no_srccheck; 1732 } 1733 return inet_sk(sk)->transparent; 1734 } 1735 1736 /* Determines whether this is a thin stream (which may suffer from 1737 * increased latency). Used to trigger latency-reducing mechanisms. 1738 */ 1739 static inline bool tcp_stream_is_thin(struct tcp_sock *tp) 1740 { 1741 return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp); 1742 } 1743 1744 /* /proc */ 1745 enum tcp_seq_states { 1746 TCP_SEQ_STATE_LISTENING, 1747 TCP_SEQ_STATE_ESTABLISHED, 1748 }; 1749 1750 int tcp_seq_open(struct inode *inode, struct file *file); 1751 1752 struct tcp_seq_afinfo { 1753 char *name; 1754 sa_family_t family; 1755 const struct file_operations *seq_fops; 1756 struct seq_operations seq_ops; 1757 }; 1758 1759 struct tcp_iter_state { 1760 struct seq_net_private p; 1761 sa_family_t family; 1762 enum tcp_seq_states state; 1763 struct sock *syn_wait_sk; 1764 int bucket, offset, sbucket, num; 1765 loff_t last_pos; 1766 }; 1767 1768 int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo); 1769 void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo); 1770 1771 extern struct request_sock_ops tcp_request_sock_ops; 1772 extern struct request_sock_ops tcp6_request_sock_ops; 1773 1774 void tcp_v4_destroy_sock(struct sock *sk); 1775 1776 struct sk_buff *tcp_gso_segment(struct sk_buff *skb, 1777 netdev_features_t features); 1778 struct sk_buff **tcp_gro_receive(struct sk_buff **head, struct sk_buff *skb); 1779 int tcp_gro_complete(struct sk_buff *skb); 1780 1781 void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr, __be32 daddr); 1782 1783 static inline u32 tcp_notsent_lowat(const struct tcp_sock *tp) 1784 { 1785 struct net *net = sock_net((struct sock *)tp); 1786 return tp->notsent_lowat ?: net->ipv4.sysctl_tcp_notsent_lowat; 1787 } 1788 1789 static inline bool tcp_stream_memory_free(const struct sock *sk) 1790 { 1791 const struct tcp_sock *tp = tcp_sk(sk); 1792 u32 notsent_bytes = tp->write_seq - tp->snd_nxt; 1793 1794 return notsent_bytes < tcp_notsent_lowat(tp); 1795 } 1796 1797 #ifdef CONFIG_PROC_FS 1798 int tcp4_proc_init(void); 1799 void tcp4_proc_exit(void); 1800 #endif 1801 1802 int tcp_rtx_synack(const struct sock *sk, struct request_sock *req); 1803 int tcp_conn_request(struct request_sock_ops *rsk_ops, 1804 const struct tcp_request_sock_ops *af_ops, 1805 struct sock *sk, struct sk_buff *skb); 1806 1807 /* TCP af-specific functions */ 1808 struct tcp_sock_af_ops { 1809 #ifdef CONFIG_TCP_MD5SIG 1810 struct tcp_md5sig_key *(*md5_lookup) (const struct sock *sk, 1811 const struct sock *addr_sk); 1812 int (*calc_md5_hash)(char *location, 1813 const struct tcp_md5sig_key *md5, 1814 const struct sock *sk, 1815 const struct sk_buff *skb); 1816 int (*md5_parse)(struct sock *sk, 1817 int optname, 1818 char __user *optval, 1819 int optlen); 1820 #endif 1821 }; 1822 1823 struct tcp_request_sock_ops { 1824 u16 mss_clamp; 1825 #ifdef CONFIG_TCP_MD5SIG 1826 struct tcp_md5sig_key *(*req_md5_lookup)(const struct sock *sk, 1827 const struct sock *addr_sk); 1828 int (*calc_md5_hash) (char *location, 1829 const struct tcp_md5sig_key *md5, 1830 const struct sock *sk, 1831 const struct sk_buff *skb); 1832 #endif 1833 void (*init_req)(struct request_sock *req, 1834 const struct sock *sk_listener, 1835 struct sk_buff *skb); 1836 #ifdef CONFIG_SYN_COOKIES 1837 __u32 (*cookie_init_seq)(const struct sk_buff *skb, 1838 __u16 *mss); 1839 #endif 1840 struct dst_entry *(*route_req)(const struct sock *sk, struct flowi *fl, 1841 const struct request_sock *req); 1842 u32 (*init_seq)(const struct sk_buff *skb); 1843 u32 (*init_ts_off)(const struct net *net, const struct sk_buff *skb); 1844 int (*send_synack)(const struct sock *sk, struct dst_entry *dst, 1845 struct flowi *fl, struct request_sock *req, 1846 struct tcp_fastopen_cookie *foc, 1847 enum tcp_synack_type synack_type); 1848 }; 1849 1850 #ifdef CONFIG_SYN_COOKIES 1851 static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops, 1852 const struct sock *sk, struct sk_buff *skb, 1853 __u16 *mss) 1854 { 1855 tcp_synq_overflow(sk); 1856 __NET_INC_STATS(sock_net(sk), LINUX_MIB_SYNCOOKIESSENT); 1857 return ops->cookie_init_seq(skb, mss); 1858 } 1859 #else 1860 static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops, 1861 const struct sock *sk, struct sk_buff *skb, 1862 __u16 *mss) 1863 { 1864 return 0; 1865 } 1866 #endif 1867 1868 int tcpv4_offload_init(void); 1869 1870 void tcp_v4_init(void); 1871 void tcp_init(void); 1872 1873 /* tcp_recovery.c */ 1874 extern void tcp_rack_mark_lost(struct sock *sk); 1875 extern void tcp_rack_advance(struct tcp_sock *tp, u8 sacked, u32 end_seq, 1876 u64 xmit_time); 1877 extern void tcp_rack_reo_timeout(struct sock *sk); 1878 extern void tcp_rack_update_reo_wnd(struct sock *sk, struct rate_sample *rs); 1879 1880 /* At how many usecs into the future should the RTO fire? */ 1881 static inline s64 tcp_rto_delta_us(const struct sock *sk) 1882 { 1883 const struct sk_buff *skb = tcp_rtx_queue_head(sk); 1884 u32 rto = inet_csk(sk)->icsk_rto; 1885 u64 rto_time_stamp_us = skb->skb_mstamp + jiffies_to_usecs(rto); 1886 1887 return rto_time_stamp_us - tcp_sk(sk)->tcp_mstamp; 1888 } 1889 1890 /* 1891 * Save and compile IPv4 options, return a pointer to it 1892 */ 1893 static inline struct ip_options_rcu *tcp_v4_save_options(struct net *net, 1894 struct sk_buff *skb) 1895 { 1896 const struct ip_options *opt = &TCP_SKB_CB(skb)->header.h4.opt; 1897 struct ip_options_rcu *dopt = NULL; 1898 1899 if (opt->optlen) { 1900 int opt_size = sizeof(*dopt) + opt->optlen; 1901 1902 dopt = kmalloc(opt_size, GFP_ATOMIC); 1903 if (dopt && __ip_options_echo(net, &dopt->opt, skb, opt)) { 1904 kfree(dopt); 1905 dopt = NULL; 1906 } 1907 } 1908 return dopt; 1909 } 1910 1911 /* locally generated TCP pure ACKs have skb->truesize == 2 1912 * (check tcp_send_ack() in net/ipv4/tcp_output.c ) 1913 * This is much faster than dissecting the packet to find out. 1914 * (Think of GRE encapsulations, IPv4, IPv6, ...) 1915 */ 1916 static inline bool skb_is_tcp_pure_ack(const struct sk_buff *skb) 1917 { 1918 return skb->truesize == 2; 1919 } 1920 1921 static inline void skb_set_tcp_pure_ack(struct sk_buff *skb) 1922 { 1923 skb->truesize = 2; 1924 } 1925 1926 static inline int tcp_inq(struct sock *sk) 1927 { 1928 struct tcp_sock *tp = tcp_sk(sk); 1929 int answ; 1930 1931 if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) { 1932 answ = 0; 1933 } else if (sock_flag(sk, SOCK_URGINLINE) || 1934 !tp->urg_data || 1935 before(tp->urg_seq, tp->copied_seq) || 1936 !before(tp->urg_seq, tp->rcv_nxt)) { 1937 1938 answ = tp->rcv_nxt - tp->copied_seq; 1939 1940 /* Subtract 1, if FIN was received */ 1941 if (answ && sock_flag(sk, SOCK_DONE)) 1942 answ--; 1943 } else { 1944 answ = tp->urg_seq - tp->copied_seq; 1945 } 1946 1947 return answ; 1948 } 1949 1950 int tcp_peek_len(struct socket *sock); 1951 1952 static inline void tcp_segs_in(struct tcp_sock *tp, const struct sk_buff *skb) 1953 { 1954 u16 segs_in; 1955 1956 segs_in = max_t(u16, 1, skb_shinfo(skb)->gso_segs); 1957 tp->segs_in += segs_in; 1958 if (skb->len > tcp_hdrlen(skb)) 1959 tp->data_segs_in += segs_in; 1960 } 1961 1962 /* 1963 * TCP listen path runs lockless. 1964 * We forced "struct sock" to be const qualified to make sure 1965 * we don't modify one of its field by mistake. 1966 * Here, we increment sk_drops which is an atomic_t, so we can safely 1967 * make sock writable again. 1968 */ 1969 static inline void tcp_listendrop(const struct sock *sk) 1970 { 1971 atomic_inc(&((struct sock *)sk)->sk_drops); 1972 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS); 1973 } 1974 1975 enum hrtimer_restart tcp_pace_kick(struct hrtimer *timer); 1976 1977 /* 1978 * Interface for adding Upper Level Protocols over TCP 1979 */ 1980 1981 #define TCP_ULP_NAME_MAX 16 1982 #define TCP_ULP_MAX 128 1983 #define TCP_ULP_BUF_MAX (TCP_ULP_NAME_MAX*TCP_ULP_MAX) 1984 1985 enum { 1986 TCP_ULP_TLS, 1987 TCP_ULP_BPF, 1988 }; 1989 1990 struct tcp_ulp_ops { 1991 struct list_head list; 1992 1993 /* initialize ulp */ 1994 int (*init)(struct sock *sk); 1995 /* cleanup ulp */ 1996 void (*release)(struct sock *sk); 1997 1998 int uid; 1999 char name[TCP_ULP_NAME_MAX]; 2000 bool user_visible; 2001 struct module *owner; 2002 }; 2003 int tcp_register_ulp(struct tcp_ulp_ops *type); 2004 void tcp_unregister_ulp(struct tcp_ulp_ops *type); 2005 int tcp_set_ulp(struct sock *sk, const char *name); 2006 int tcp_set_ulp_id(struct sock *sk, const int ulp); 2007 void tcp_get_available_ulp(char *buf, size_t len); 2008 void tcp_cleanup_ulp(struct sock *sk); 2009 2010 /* Call BPF_SOCK_OPS program that returns an int. If the return value 2011 * is < 0, then the BPF op failed (for example if the loaded BPF 2012 * program does not support the chosen operation or there is no BPF 2013 * program loaded). 2014 */ 2015 #ifdef CONFIG_BPF 2016 static inline int tcp_call_bpf(struct sock *sk, int op, u32 nargs, u32 *args) 2017 { 2018 struct bpf_sock_ops_kern sock_ops; 2019 int ret; 2020 2021 memset(&sock_ops, 0, offsetof(struct bpf_sock_ops_kern, temp)); 2022 if (sk_fullsock(sk)) { 2023 sock_ops.is_fullsock = 1; 2024 sock_owned_by_me(sk); 2025 } 2026 2027 sock_ops.sk = sk; 2028 sock_ops.op = op; 2029 if (nargs > 0) 2030 memcpy(sock_ops.args, args, nargs * sizeof(*args)); 2031 2032 ret = BPF_CGROUP_RUN_PROG_SOCK_OPS(&sock_ops); 2033 if (ret == 0) 2034 ret = sock_ops.reply; 2035 else 2036 ret = -1; 2037 return ret; 2038 } 2039 2040 static inline int tcp_call_bpf_2arg(struct sock *sk, int op, u32 arg1, u32 arg2) 2041 { 2042 u32 args[2] = {arg1, arg2}; 2043 2044 return tcp_call_bpf(sk, op, 2, args); 2045 } 2046 2047 static inline int tcp_call_bpf_3arg(struct sock *sk, int op, u32 arg1, u32 arg2, 2048 u32 arg3) 2049 { 2050 u32 args[3] = {arg1, arg2, arg3}; 2051 2052 return tcp_call_bpf(sk, op, 3, args); 2053 } 2054 2055 #else 2056 static inline int tcp_call_bpf(struct sock *sk, int op, u32 nargs, u32 *args) 2057 { 2058 return -EPERM; 2059 } 2060 2061 static inline int tcp_call_bpf_2arg(struct sock *sk, int op, u32 arg1, u32 arg2) 2062 { 2063 return -EPERM; 2064 } 2065 2066 static inline int tcp_call_bpf_3arg(struct sock *sk, int op, u32 arg1, u32 arg2, 2067 u32 arg3) 2068 { 2069 return -EPERM; 2070 } 2071 2072 #endif 2073 2074 static inline u32 tcp_timeout_init(struct sock *sk) 2075 { 2076 int timeout; 2077 2078 timeout = tcp_call_bpf(sk, BPF_SOCK_OPS_TIMEOUT_INIT, 0, NULL); 2079 2080 if (timeout <= 0) 2081 timeout = TCP_TIMEOUT_INIT; 2082 return timeout; 2083 } 2084 2085 static inline u32 tcp_rwnd_init_bpf(struct sock *sk) 2086 { 2087 int rwnd; 2088 2089 rwnd = tcp_call_bpf(sk, BPF_SOCK_OPS_RWND_INIT, 0, NULL); 2090 2091 if (rwnd < 0) 2092 rwnd = 0; 2093 return rwnd; 2094 } 2095 2096 static inline bool tcp_bpf_ca_needs_ecn(struct sock *sk) 2097 { 2098 return (tcp_call_bpf(sk, BPF_SOCK_OPS_NEEDS_ECN, 0, NULL) == 1); 2099 } 2100 2101 #if IS_ENABLED(CONFIG_SMC) 2102 extern struct static_key_false tcp_have_smc; 2103 #endif 2104 #endif /* _TCP_H */ 2105