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 int tcp_set_rcvlowat(struct sock *sk, int val); 406 void tcp_data_ready(struct sock *sk); 407 int tcp_mmap(struct file *file, struct socket *sock, 408 struct vm_area_struct *vma); 409 void tcp_parse_options(const struct net *net, const struct sk_buff *skb, 410 struct tcp_options_received *opt_rx, 411 int estab, struct tcp_fastopen_cookie *foc); 412 const u8 *tcp_parse_md5sig_option(const struct tcphdr *th); 413 414 /* 415 * TCP v4 functions exported for the inet6 API 416 */ 417 418 void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb); 419 void tcp_v4_mtu_reduced(struct sock *sk); 420 void tcp_req_err(struct sock *sk, u32 seq, bool abort); 421 int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb); 422 struct sock *tcp_create_openreq_child(const struct sock *sk, 423 struct request_sock *req, 424 struct sk_buff *skb); 425 void tcp_ca_openreq_child(struct sock *sk, const struct dst_entry *dst); 426 struct sock *tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb, 427 struct request_sock *req, 428 struct dst_entry *dst, 429 struct request_sock *req_unhash, 430 bool *own_req); 431 int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb); 432 int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len); 433 int tcp_connect(struct sock *sk); 434 enum tcp_synack_type { 435 TCP_SYNACK_NORMAL, 436 TCP_SYNACK_FASTOPEN, 437 TCP_SYNACK_COOKIE, 438 }; 439 struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst, 440 struct request_sock *req, 441 struct tcp_fastopen_cookie *foc, 442 enum tcp_synack_type synack_type); 443 int tcp_disconnect(struct sock *sk, int flags); 444 445 void tcp_finish_connect(struct sock *sk, struct sk_buff *skb); 446 int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size); 447 void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb); 448 449 /* From syncookies.c */ 450 struct sock *tcp_get_cookie_sock(struct sock *sk, struct sk_buff *skb, 451 struct request_sock *req, 452 struct dst_entry *dst, u32 tsoff); 453 int __cookie_v4_check(const struct iphdr *iph, const struct tcphdr *th, 454 u32 cookie); 455 struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb); 456 #ifdef CONFIG_SYN_COOKIES 457 458 /* Syncookies use a monotonic timer which increments every 60 seconds. 459 * This counter is used both as a hash input and partially encoded into 460 * the cookie value. A cookie is only validated further if the delta 461 * between the current counter value and the encoded one is less than this, 462 * i.e. a sent cookie is valid only at most for 2*60 seconds (or less if 463 * the counter advances immediately after a cookie is generated). 464 */ 465 #define MAX_SYNCOOKIE_AGE 2 466 #define TCP_SYNCOOKIE_PERIOD (60 * HZ) 467 #define TCP_SYNCOOKIE_VALID (MAX_SYNCOOKIE_AGE * TCP_SYNCOOKIE_PERIOD) 468 469 /* syncookies: remember time of last synqueue overflow 470 * But do not dirty this field too often (once per second is enough) 471 * It is racy as we do not hold a lock, but race is very minor. 472 */ 473 static inline void tcp_synq_overflow(const struct sock *sk) 474 { 475 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp; 476 unsigned long now = jiffies; 477 478 if (time_after(now, last_overflow + HZ)) 479 tcp_sk(sk)->rx_opt.ts_recent_stamp = now; 480 } 481 482 /* syncookies: no recent synqueue overflow on this listening socket? */ 483 static inline bool tcp_synq_no_recent_overflow(const struct sock *sk) 484 { 485 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp; 486 487 return time_after(jiffies, last_overflow + TCP_SYNCOOKIE_VALID); 488 } 489 490 static inline u32 tcp_cookie_time(void) 491 { 492 u64 val = get_jiffies_64(); 493 494 do_div(val, TCP_SYNCOOKIE_PERIOD); 495 return val; 496 } 497 498 u32 __cookie_v4_init_sequence(const struct iphdr *iph, const struct tcphdr *th, 499 u16 *mssp); 500 __u32 cookie_v4_init_sequence(const struct sk_buff *skb, __u16 *mss); 501 u64 cookie_init_timestamp(struct request_sock *req); 502 bool cookie_timestamp_decode(const struct net *net, 503 struct tcp_options_received *opt); 504 bool cookie_ecn_ok(const struct tcp_options_received *opt, 505 const struct net *net, const struct dst_entry *dst); 506 507 /* From net/ipv6/syncookies.c */ 508 int __cookie_v6_check(const struct ipv6hdr *iph, const struct tcphdr *th, 509 u32 cookie); 510 struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb); 511 512 u32 __cookie_v6_init_sequence(const struct ipv6hdr *iph, 513 const struct tcphdr *th, u16 *mssp); 514 __u32 cookie_v6_init_sequence(const struct sk_buff *skb, __u16 *mss); 515 #endif 516 /* tcp_output.c */ 517 518 void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss, 519 int nonagle); 520 int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs); 521 int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs); 522 void tcp_retransmit_timer(struct sock *sk); 523 void tcp_xmit_retransmit_queue(struct sock *); 524 void tcp_simple_retransmit(struct sock *); 525 void tcp_enter_recovery(struct sock *sk, bool ece_ack); 526 int tcp_trim_head(struct sock *, struct sk_buff *, u32); 527 enum tcp_queue { 528 TCP_FRAG_IN_WRITE_QUEUE, 529 TCP_FRAG_IN_RTX_QUEUE, 530 }; 531 int tcp_fragment(struct sock *sk, enum tcp_queue tcp_queue, 532 struct sk_buff *skb, u32 len, 533 unsigned int mss_now, gfp_t gfp); 534 535 void tcp_send_probe0(struct sock *); 536 void tcp_send_partial(struct sock *); 537 int tcp_write_wakeup(struct sock *, int mib); 538 void tcp_send_fin(struct sock *sk); 539 void tcp_send_active_reset(struct sock *sk, gfp_t priority); 540 int tcp_send_synack(struct sock *); 541 void tcp_push_one(struct sock *, unsigned int mss_now); 542 void tcp_send_ack(struct sock *sk); 543 void tcp_send_delayed_ack(struct sock *sk); 544 void tcp_send_loss_probe(struct sock *sk); 545 bool tcp_schedule_loss_probe(struct sock *sk, bool advancing_rto); 546 void tcp_skb_collapse_tstamp(struct sk_buff *skb, 547 const struct sk_buff *next_skb); 548 549 /* tcp_input.c */ 550 void tcp_rearm_rto(struct sock *sk); 551 void tcp_synack_rtt_meas(struct sock *sk, struct request_sock *req); 552 void tcp_reset(struct sock *sk); 553 void tcp_skb_mark_lost_uncond_verify(struct tcp_sock *tp, struct sk_buff *skb); 554 void tcp_fin(struct sock *sk); 555 556 /* tcp_timer.c */ 557 void tcp_init_xmit_timers(struct sock *); 558 static inline void tcp_clear_xmit_timers(struct sock *sk) 559 { 560 hrtimer_cancel(&tcp_sk(sk)->pacing_timer); 561 inet_csk_clear_xmit_timers(sk); 562 } 563 564 unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu); 565 unsigned int tcp_current_mss(struct sock *sk); 566 567 /* Bound MSS / TSO packet size with the half of the window */ 568 static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize) 569 { 570 int cutoff; 571 572 /* When peer uses tiny windows, there is no use in packetizing 573 * to sub-MSS pieces for the sake of SWS or making sure there 574 * are enough packets in the pipe for fast recovery. 575 * 576 * On the other hand, for extremely large MSS devices, handling 577 * smaller than MSS windows in this way does make sense. 578 */ 579 if (tp->max_window > TCP_MSS_DEFAULT) 580 cutoff = (tp->max_window >> 1); 581 else 582 cutoff = tp->max_window; 583 584 if (cutoff && pktsize > cutoff) 585 return max_t(int, cutoff, 68U - tp->tcp_header_len); 586 else 587 return pktsize; 588 } 589 590 /* tcp.c */ 591 void tcp_get_info(struct sock *, struct tcp_info *); 592 593 /* Read 'sendfile()'-style from a TCP socket */ 594 int tcp_read_sock(struct sock *sk, read_descriptor_t *desc, 595 sk_read_actor_t recv_actor); 596 597 void tcp_initialize_rcv_mss(struct sock *sk); 598 599 int tcp_mtu_to_mss(struct sock *sk, int pmtu); 600 int tcp_mss_to_mtu(struct sock *sk, int mss); 601 void tcp_mtup_init(struct sock *sk); 602 void tcp_init_buffer_space(struct sock *sk); 603 604 static inline void tcp_bound_rto(const struct sock *sk) 605 { 606 if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX) 607 inet_csk(sk)->icsk_rto = TCP_RTO_MAX; 608 } 609 610 static inline u32 __tcp_set_rto(const struct tcp_sock *tp) 611 { 612 return usecs_to_jiffies((tp->srtt_us >> 3) + tp->rttvar_us); 613 } 614 615 static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd) 616 { 617 tp->pred_flags = htonl((tp->tcp_header_len << 26) | 618 ntohl(TCP_FLAG_ACK) | 619 snd_wnd); 620 } 621 622 static inline void tcp_fast_path_on(struct tcp_sock *tp) 623 { 624 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale); 625 } 626 627 static inline void tcp_fast_path_check(struct sock *sk) 628 { 629 struct tcp_sock *tp = tcp_sk(sk); 630 631 if (RB_EMPTY_ROOT(&tp->out_of_order_queue) && 632 tp->rcv_wnd && 633 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf && 634 !tp->urg_data) 635 tcp_fast_path_on(tp); 636 } 637 638 /* Compute the actual rto_min value */ 639 static inline u32 tcp_rto_min(struct sock *sk) 640 { 641 const struct dst_entry *dst = __sk_dst_get(sk); 642 u32 rto_min = TCP_RTO_MIN; 643 644 if (dst && dst_metric_locked(dst, RTAX_RTO_MIN)) 645 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN); 646 return rto_min; 647 } 648 649 static inline u32 tcp_rto_min_us(struct sock *sk) 650 { 651 return jiffies_to_usecs(tcp_rto_min(sk)); 652 } 653 654 static inline bool tcp_ca_dst_locked(const struct dst_entry *dst) 655 { 656 return dst_metric_locked(dst, RTAX_CC_ALGO); 657 } 658 659 /* Minimum RTT in usec. ~0 means not available. */ 660 static inline u32 tcp_min_rtt(const struct tcp_sock *tp) 661 { 662 return minmax_get(&tp->rtt_min); 663 } 664 665 /* Compute the actual receive window we are currently advertising. 666 * Rcv_nxt can be after the window if our peer push more data 667 * than the offered window. 668 */ 669 static inline u32 tcp_receive_window(const struct tcp_sock *tp) 670 { 671 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt; 672 673 if (win < 0) 674 win = 0; 675 return (u32) win; 676 } 677 678 /* Choose a new window, without checks for shrinking, and without 679 * scaling applied to the result. The caller does these things 680 * if necessary. This is a "raw" window selection. 681 */ 682 u32 __tcp_select_window(struct sock *sk); 683 684 void tcp_send_window_probe(struct sock *sk); 685 686 /* TCP uses 32bit jiffies to save some space. 687 * Note that this is different from tcp_time_stamp, which 688 * historically has been the same until linux-4.13. 689 */ 690 #define tcp_jiffies32 ((u32)jiffies) 691 692 /* 693 * Deliver a 32bit value for TCP timestamp option (RFC 7323) 694 * It is no longer tied to jiffies, but to 1 ms clock. 695 * Note: double check if you want to use tcp_jiffies32 instead of this. 696 */ 697 #define TCP_TS_HZ 1000 698 699 static inline u64 tcp_clock_ns(void) 700 { 701 return local_clock(); 702 } 703 704 static inline u64 tcp_clock_us(void) 705 { 706 return div_u64(tcp_clock_ns(), NSEC_PER_USEC); 707 } 708 709 /* This should only be used in contexts where tp->tcp_mstamp is up to date */ 710 static inline u32 tcp_time_stamp(const struct tcp_sock *tp) 711 { 712 return div_u64(tp->tcp_mstamp, USEC_PER_SEC / TCP_TS_HZ); 713 } 714 715 /* Could use tcp_clock_us() / 1000, but this version uses a single divide */ 716 static inline u32 tcp_time_stamp_raw(void) 717 { 718 return div_u64(tcp_clock_ns(), NSEC_PER_SEC / TCP_TS_HZ); 719 } 720 721 722 /* Refresh 1us clock of a TCP socket, 723 * ensuring monotically increasing values. 724 */ 725 static inline void tcp_mstamp_refresh(struct tcp_sock *tp) 726 { 727 u64 val = tcp_clock_us(); 728 729 if (val > tp->tcp_mstamp) 730 tp->tcp_mstamp = val; 731 } 732 733 static inline u32 tcp_stamp_us_delta(u64 t1, u64 t0) 734 { 735 return max_t(s64, t1 - t0, 0); 736 } 737 738 static inline u32 tcp_skb_timestamp(const struct sk_buff *skb) 739 { 740 return div_u64(skb->skb_mstamp, USEC_PER_SEC / TCP_TS_HZ); 741 } 742 743 744 #define tcp_flag_byte(th) (((u_int8_t *)th)[13]) 745 746 #define TCPHDR_FIN 0x01 747 #define TCPHDR_SYN 0x02 748 #define TCPHDR_RST 0x04 749 #define TCPHDR_PSH 0x08 750 #define TCPHDR_ACK 0x10 751 #define TCPHDR_URG 0x20 752 #define TCPHDR_ECE 0x40 753 #define TCPHDR_CWR 0x80 754 755 #define TCPHDR_SYN_ECN (TCPHDR_SYN | TCPHDR_ECE | TCPHDR_CWR) 756 757 /* This is what the send packet queuing engine uses to pass 758 * TCP per-packet control information to the transmission code. 759 * We also store the host-order sequence numbers in here too. 760 * This is 44 bytes if IPV6 is enabled. 761 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately. 762 */ 763 struct tcp_skb_cb { 764 __u32 seq; /* Starting sequence number */ 765 __u32 end_seq; /* SEQ + FIN + SYN + datalen */ 766 union { 767 /* Note : tcp_tw_isn is used in input path only 768 * (isn chosen by tcp_timewait_state_process()) 769 * 770 * tcp_gso_segs/size are used in write queue only, 771 * cf tcp_skb_pcount()/tcp_skb_mss() 772 */ 773 __u32 tcp_tw_isn; 774 struct { 775 u16 tcp_gso_segs; 776 u16 tcp_gso_size; 777 }; 778 }; 779 __u8 tcp_flags; /* TCP header flags. (tcp[13]) */ 780 781 __u8 sacked; /* State flags for SACK. */ 782 #define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */ 783 #define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */ 784 #define TCPCB_LOST 0x04 /* SKB is lost */ 785 #define TCPCB_TAGBITS 0x07 /* All tag bits */ 786 #define TCPCB_REPAIRED 0x10 /* SKB repaired (no skb_mstamp) */ 787 #define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */ 788 #define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS| \ 789 TCPCB_REPAIRED) 790 791 __u8 ip_dsfield; /* IPv4 tos or IPv6 dsfield */ 792 __u8 txstamp_ack:1, /* Record TX timestamp for ack? */ 793 eor:1, /* Is skb MSG_EOR marked? */ 794 has_rxtstamp:1, /* SKB has a RX timestamp */ 795 unused:5; 796 __u32 ack_seq; /* Sequence number ACK'd */ 797 union { 798 struct { 799 /* There is space for up to 24 bytes */ 800 __u32 in_flight:30,/* Bytes in flight at transmit */ 801 is_app_limited:1, /* cwnd not fully used? */ 802 unused:1; 803 /* pkts S/ACKed so far upon tx of skb, incl retrans: */ 804 __u32 delivered; 805 /* start of send pipeline phase */ 806 u64 first_tx_mstamp; 807 /* when we reached the "delivered" count */ 808 u64 delivered_mstamp; 809 } tx; /* only used for outgoing skbs */ 810 union { 811 struct inet_skb_parm h4; 812 #if IS_ENABLED(CONFIG_IPV6) 813 struct inet6_skb_parm h6; 814 #endif 815 } header; /* For incoming skbs */ 816 struct { 817 __u32 key; 818 __u32 flags; 819 struct bpf_map *map; 820 void *data_end; 821 } bpf; 822 }; 823 }; 824 825 #define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0])) 826 827 828 #if IS_ENABLED(CONFIG_IPV6) 829 /* This is the variant of inet6_iif() that must be used by TCP, 830 * as TCP moves IP6CB into a different location in skb->cb[] 831 */ 832 static inline int tcp_v6_iif(const struct sk_buff *skb) 833 { 834 bool l3_slave = ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags); 835 836 return l3_slave ? skb->skb_iif : TCP_SKB_CB(skb)->header.h6.iif; 837 } 838 839 /* TCP_SKB_CB reference means this can not be used from early demux */ 840 static inline int tcp_v6_sdif(const struct sk_buff *skb) 841 { 842 #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV) 843 if (skb && ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags)) 844 return TCP_SKB_CB(skb)->header.h6.iif; 845 #endif 846 return 0; 847 } 848 #endif 849 850 static inline bool inet_exact_dif_match(struct net *net, struct sk_buff *skb) 851 { 852 #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV) 853 if (!net->ipv4.sysctl_tcp_l3mdev_accept && 854 skb && ipv4_l3mdev_skb(IPCB(skb)->flags)) 855 return true; 856 #endif 857 return false; 858 } 859 860 /* TCP_SKB_CB reference means this can not be used from early demux */ 861 static inline int tcp_v4_sdif(struct sk_buff *skb) 862 { 863 #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV) 864 if (skb && ipv4_l3mdev_skb(TCP_SKB_CB(skb)->header.h4.flags)) 865 return TCP_SKB_CB(skb)->header.h4.iif; 866 #endif 867 return 0; 868 } 869 870 /* Due to TSO, an SKB can be composed of multiple actual 871 * packets. To keep these tracked properly, we use this. 872 */ 873 static inline int tcp_skb_pcount(const struct sk_buff *skb) 874 { 875 return TCP_SKB_CB(skb)->tcp_gso_segs; 876 } 877 878 static inline void tcp_skb_pcount_set(struct sk_buff *skb, int segs) 879 { 880 TCP_SKB_CB(skb)->tcp_gso_segs = segs; 881 } 882 883 static inline void tcp_skb_pcount_add(struct sk_buff *skb, int segs) 884 { 885 TCP_SKB_CB(skb)->tcp_gso_segs += segs; 886 } 887 888 /* This is valid iff skb is in write queue and tcp_skb_pcount() > 1. */ 889 static inline int tcp_skb_mss(const struct sk_buff *skb) 890 { 891 return TCP_SKB_CB(skb)->tcp_gso_size; 892 } 893 894 static inline bool tcp_skb_can_collapse_to(const struct sk_buff *skb) 895 { 896 return likely(!TCP_SKB_CB(skb)->eor); 897 } 898 899 /* Events passed to congestion control interface */ 900 enum tcp_ca_event { 901 CA_EVENT_TX_START, /* first transmit when no packets in flight */ 902 CA_EVENT_CWND_RESTART, /* congestion window restart */ 903 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */ 904 CA_EVENT_LOSS, /* loss timeout */ 905 CA_EVENT_ECN_NO_CE, /* ECT set, but not CE marked */ 906 CA_EVENT_ECN_IS_CE, /* received CE marked IP packet */ 907 CA_EVENT_DELAYED_ACK, /* Delayed ack is sent */ 908 CA_EVENT_NON_DELAYED_ACK, 909 }; 910 911 /* Information about inbound ACK, passed to cong_ops->in_ack_event() */ 912 enum tcp_ca_ack_event_flags { 913 CA_ACK_SLOWPATH = (1 << 0), /* In slow path processing */ 914 CA_ACK_WIN_UPDATE = (1 << 1), /* ACK updated window */ 915 CA_ACK_ECE = (1 << 2), /* ECE bit is set on ack */ 916 }; 917 918 /* 919 * Interface for adding new TCP congestion control handlers 920 */ 921 #define TCP_CA_NAME_MAX 16 922 #define TCP_CA_MAX 128 923 #define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX) 924 925 #define TCP_CA_UNSPEC 0 926 927 /* Algorithm can be set on socket without CAP_NET_ADMIN privileges */ 928 #define TCP_CONG_NON_RESTRICTED 0x1 929 /* Requires ECN/ECT set on all packets */ 930 #define TCP_CONG_NEEDS_ECN 0x2 931 932 union tcp_cc_info; 933 934 struct ack_sample { 935 u32 pkts_acked; 936 s32 rtt_us; 937 u32 in_flight; 938 }; 939 940 /* A rate sample measures the number of (original/retransmitted) data 941 * packets delivered "delivered" over an interval of time "interval_us". 942 * The tcp_rate.c code fills in the rate sample, and congestion 943 * control modules that define a cong_control function to run at the end 944 * of ACK processing can optionally chose to consult this sample when 945 * setting cwnd and pacing rate. 946 * A sample is invalid if "delivered" or "interval_us" is negative. 947 */ 948 struct rate_sample { 949 u64 prior_mstamp; /* starting timestamp for interval */ 950 u32 prior_delivered; /* tp->delivered at "prior_mstamp" */ 951 s32 delivered; /* number of packets delivered over interval */ 952 long interval_us; /* time for tp->delivered to incr "delivered" */ 953 long rtt_us; /* RTT of last (S)ACKed packet (or -1) */ 954 int losses; /* number of packets marked lost upon ACK */ 955 u32 acked_sacked; /* number of packets newly (S)ACKed upon ACK */ 956 u32 prior_in_flight; /* in flight before this ACK */ 957 bool is_app_limited; /* is sample from packet with bubble in pipe? */ 958 bool is_retrans; /* is sample from retransmission? */ 959 bool is_ack_delayed; /* is this (likely) a delayed ACK? */ 960 }; 961 962 struct tcp_congestion_ops { 963 struct list_head list; 964 u32 key; 965 u32 flags; 966 967 /* initialize private data (optional) */ 968 void (*init)(struct sock *sk); 969 /* cleanup private data (optional) */ 970 void (*release)(struct sock *sk); 971 972 /* return slow start threshold (required) */ 973 u32 (*ssthresh)(struct sock *sk); 974 /* do new cwnd calculation (required) */ 975 void (*cong_avoid)(struct sock *sk, u32 ack, u32 acked); 976 /* call before changing ca_state (optional) */ 977 void (*set_state)(struct sock *sk, u8 new_state); 978 /* call when cwnd event occurs (optional) */ 979 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev); 980 /* call when ack arrives (optional) */ 981 void (*in_ack_event)(struct sock *sk, u32 flags); 982 /* new value of cwnd after loss (required) */ 983 u32 (*undo_cwnd)(struct sock *sk); 984 /* hook for packet ack accounting (optional) */ 985 void (*pkts_acked)(struct sock *sk, const struct ack_sample *sample); 986 /* override sysctl_tcp_min_tso_segs */ 987 u32 (*min_tso_segs)(struct sock *sk); 988 /* returns the multiplier used in tcp_sndbuf_expand (optional) */ 989 u32 (*sndbuf_expand)(struct sock *sk); 990 /* call when packets are delivered to update cwnd and pacing rate, 991 * after all the ca_state processing. (optional) 992 */ 993 void (*cong_control)(struct sock *sk, const struct rate_sample *rs); 994 /* get info for inet_diag (optional) */ 995 size_t (*get_info)(struct sock *sk, u32 ext, int *attr, 996 union tcp_cc_info *info); 997 998 char name[TCP_CA_NAME_MAX]; 999 struct module *owner; 1000 }; 1001 1002 int tcp_register_congestion_control(struct tcp_congestion_ops *type); 1003 void tcp_unregister_congestion_control(struct tcp_congestion_ops *type); 1004 1005 void tcp_assign_congestion_control(struct sock *sk); 1006 void tcp_init_congestion_control(struct sock *sk); 1007 void tcp_cleanup_congestion_control(struct sock *sk); 1008 int tcp_set_default_congestion_control(struct net *net, const char *name); 1009 void tcp_get_default_congestion_control(struct net *net, char *name); 1010 void tcp_get_available_congestion_control(char *buf, size_t len); 1011 void tcp_get_allowed_congestion_control(char *buf, size_t len); 1012 int tcp_set_allowed_congestion_control(char *allowed); 1013 int tcp_set_congestion_control(struct sock *sk, const char *name, bool load, bool reinit); 1014 u32 tcp_slow_start(struct tcp_sock *tp, u32 acked); 1015 void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w, u32 acked); 1016 1017 u32 tcp_reno_ssthresh(struct sock *sk); 1018 u32 tcp_reno_undo_cwnd(struct sock *sk); 1019 void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 acked); 1020 extern struct tcp_congestion_ops tcp_reno; 1021 1022 struct tcp_congestion_ops *tcp_ca_find_key(u32 key); 1023 u32 tcp_ca_get_key_by_name(struct net *net, const char *name, bool *ecn_ca); 1024 #ifdef CONFIG_INET 1025 char *tcp_ca_get_name_by_key(u32 key, char *buffer); 1026 #else 1027 static inline char *tcp_ca_get_name_by_key(u32 key, char *buffer) 1028 { 1029 return NULL; 1030 } 1031 #endif 1032 1033 static inline bool tcp_ca_needs_ecn(const struct sock *sk) 1034 { 1035 const struct inet_connection_sock *icsk = inet_csk(sk); 1036 1037 return icsk->icsk_ca_ops->flags & TCP_CONG_NEEDS_ECN; 1038 } 1039 1040 static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state) 1041 { 1042 struct inet_connection_sock *icsk = inet_csk(sk); 1043 1044 if (icsk->icsk_ca_ops->set_state) 1045 icsk->icsk_ca_ops->set_state(sk, ca_state); 1046 icsk->icsk_ca_state = ca_state; 1047 } 1048 1049 static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event) 1050 { 1051 const struct inet_connection_sock *icsk = inet_csk(sk); 1052 1053 if (icsk->icsk_ca_ops->cwnd_event) 1054 icsk->icsk_ca_ops->cwnd_event(sk, event); 1055 } 1056 1057 /* From tcp_rate.c */ 1058 void tcp_rate_skb_sent(struct sock *sk, struct sk_buff *skb); 1059 void tcp_rate_skb_delivered(struct sock *sk, struct sk_buff *skb, 1060 struct rate_sample *rs); 1061 void tcp_rate_gen(struct sock *sk, u32 delivered, u32 lost, 1062 bool is_sack_reneg, struct rate_sample *rs); 1063 void tcp_rate_check_app_limited(struct sock *sk); 1064 1065 /* These functions determine how the current flow behaves in respect of SACK 1066 * handling. SACK is negotiated with the peer, and therefore it can vary 1067 * between different flows. 1068 * 1069 * tcp_is_sack - SACK enabled 1070 * tcp_is_reno - No SACK 1071 */ 1072 static inline int tcp_is_sack(const struct tcp_sock *tp) 1073 { 1074 return tp->rx_opt.sack_ok; 1075 } 1076 1077 static inline bool tcp_is_reno(const struct tcp_sock *tp) 1078 { 1079 return !tcp_is_sack(tp); 1080 } 1081 1082 static inline unsigned int tcp_left_out(const struct tcp_sock *tp) 1083 { 1084 return tp->sacked_out + tp->lost_out; 1085 } 1086 1087 /* This determines how many packets are "in the network" to the best 1088 * of our knowledge. In many cases it is conservative, but where 1089 * detailed information is available from the receiver (via SACK 1090 * blocks etc.) we can make more aggressive calculations. 1091 * 1092 * Use this for decisions involving congestion control, use just 1093 * tp->packets_out to determine if the send queue is empty or not. 1094 * 1095 * Read this equation as: 1096 * 1097 * "Packets sent once on transmission queue" MINUS 1098 * "Packets left network, but not honestly ACKed yet" PLUS 1099 * "Packets fast retransmitted" 1100 */ 1101 static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp) 1102 { 1103 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out; 1104 } 1105 1106 #define TCP_INFINITE_SSTHRESH 0x7fffffff 1107 1108 static inline bool tcp_in_slow_start(const struct tcp_sock *tp) 1109 { 1110 return tp->snd_cwnd < tp->snd_ssthresh; 1111 } 1112 1113 static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp) 1114 { 1115 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH; 1116 } 1117 1118 static inline bool tcp_in_cwnd_reduction(const struct sock *sk) 1119 { 1120 return (TCPF_CA_CWR | TCPF_CA_Recovery) & 1121 (1 << inet_csk(sk)->icsk_ca_state); 1122 } 1123 1124 /* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd. 1125 * The exception is cwnd reduction phase, when cwnd is decreasing towards 1126 * ssthresh. 1127 */ 1128 static inline __u32 tcp_current_ssthresh(const struct sock *sk) 1129 { 1130 const struct tcp_sock *tp = tcp_sk(sk); 1131 1132 if (tcp_in_cwnd_reduction(sk)) 1133 return tp->snd_ssthresh; 1134 else 1135 return max(tp->snd_ssthresh, 1136 ((tp->snd_cwnd >> 1) + 1137 (tp->snd_cwnd >> 2))); 1138 } 1139 1140 /* Use define here intentionally to get WARN_ON location shown at the caller */ 1141 #define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out) 1142 1143 void tcp_enter_cwr(struct sock *sk); 1144 __u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst); 1145 1146 /* The maximum number of MSS of available cwnd for which TSO defers 1147 * sending if not using sysctl_tcp_tso_win_divisor. 1148 */ 1149 static inline __u32 tcp_max_tso_deferred_mss(const struct tcp_sock *tp) 1150 { 1151 return 3; 1152 } 1153 1154 /* Returns end sequence number of the receiver's advertised window */ 1155 static inline u32 tcp_wnd_end(const struct tcp_sock *tp) 1156 { 1157 return tp->snd_una + tp->snd_wnd; 1158 } 1159 1160 /* We follow the spirit of RFC2861 to validate cwnd but implement a more 1161 * flexible approach. The RFC suggests cwnd should not be raised unless 1162 * it was fully used previously. And that's exactly what we do in 1163 * congestion avoidance mode. But in slow start we allow cwnd to grow 1164 * as long as the application has used half the cwnd. 1165 * Example : 1166 * cwnd is 10 (IW10), but application sends 9 frames. 1167 * We allow cwnd to reach 18 when all frames are ACKed. 1168 * This check is safe because it's as aggressive as slow start which already 1169 * risks 100% overshoot. The advantage is that we discourage application to 1170 * either send more filler packets or data to artificially blow up the cwnd 1171 * usage, and allow application-limited process to probe bw more aggressively. 1172 */ 1173 static inline bool tcp_is_cwnd_limited(const struct sock *sk) 1174 { 1175 const struct tcp_sock *tp = tcp_sk(sk); 1176 1177 /* If in slow start, ensure cwnd grows to twice what was ACKed. */ 1178 if (tcp_in_slow_start(tp)) 1179 return tp->snd_cwnd < 2 * tp->max_packets_out; 1180 1181 return tp->is_cwnd_limited; 1182 } 1183 1184 /* Something is really bad, we could not queue an additional packet, 1185 * because qdisc is full or receiver sent a 0 window. 1186 * We do not want to add fuel to the fire, or abort too early, 1187 * so make sure the timer we arm now is at least 200ms in the future, 1188 * regardless of current icsk_rto value (as it could be ~2ms) 1189 */ 1190 static inline unsigned long tcp_probe0_base(const struct sock *sk) 1191 { 1192 return max_t(unsigned long, inet_csk(sk)->icsk_rto, TCP_RTO_MIN); 1193 } 1194 1195 /* Variant of inet_csk_rto_backoff() used for zero window probes */ 1196 static inline unsigned long tcp_probe0_when(const struct sock *sk, 1197 unsigned long max_when) 1198 { 1199 u64 when = (u64)tcp_probe0_base(sk) << inet_csk(sk)->icsk_backoff; 1200 1201 return (unsigned long)min_t(u64, when, max_when); 1202 } 1203 1204 static inline void tcp_check_probe_timer(struct sock *sk) 1205 { 1206 if (!tcp_sk(sk)->packets_out && !inet_csk(sk)->icsk_pending) 1207 inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0, 1208 tcp_probe0_base(sk), TCP_RTO_MAX); 1209 } 1210 1211 static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq) 1212 { 1213 tp->snd_wl1 = seq; 1214 } 1215 1216 static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq) 1217 { 1218 tp->snd_wl1 = seq; 1219 } 1220 1221 /* 1222 * Calculate(/check) TCP checksum 1223 */ 1224 static inline __sum16 tcp_v4_check(int len, __be32 saddr, 1225 __be32 daddr, __wsum base) 1226 { 1227 return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base); 1228 } 1229 1230 static inline __sum16 __tcp_checksum_complete(struct sk_buff *skb) 1231 { 1232 return __skb_checksum_complete(skb); 1233 } 1234 1235 static inline bool tcp_checksum_complete(struct sk_buff *skb) 1236 { 1237 return !skb_csum_unnecessary(skb) && 1238 __tcp_checksum_complete(skb); 1239 } 1240 1241 bool tcp_add_backlog(struct sock *sk, struct sk_buff *skb); 1242 int tcp_filter(struct sock *sk, struct sk_buff *skb); 1243 1244 #undef STATE_TRACE 1245 1246 #ifdef STATE_TRACE 1247 static const char *statename[]={ 1248 "Unused","Established","Syn Sent","Syn Recv", 1249 "Fin Wait 1","Fin Wait 2","Time Wait", "Close", 1250 "Close Wait","Last ACK","Listen","Closing" 1251 }; 1252 #endif 1253 void tcp_set_state(struct sock *sk, int state); 1254 1255 void tcp_done(struct sock *sk); 1256 1257 int tcp_abort(struct sock *sk, int err); 1258 1259 static inline void tcp_sack_reset(struct tcp_options_received *rx_opt) 1260 { 1261 rx_opt->dsack = 0; 1262 rx_opt->num_sacks = 0; 1263 } 1264 1265 u32 tcp_default_init_rwnd(u32 mss); 1266 void tcp_cwnd_restart(struct sock *sk, s32 delta); 1267 1268 static inline void tcp_slow_start_after_idle_check(struct sock *sk) 1269 { 1270 const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops; 1271 struct tcp_sock *tp = tcp_sk(sk); 1272 s32 delta; 1273 1274 if (!sock_net(sk)->ipv4.sysctl_tcp_slow_start_after_idle || tp->packets_out || 1275 ca_ops->cong_control) 1276 return; 1277 delta = tcp_jiffies32 - tp->lsndtime; 1278 if (delta > inet_csk(sk)->icsk_rto) 1279 tcp_cwnd_restart(sk, delta); 1280 } 1281 1282 /* Determine a window scaling and initial window to offer. */ 1283 void tcp_select_initial_window(const struct sock *sk, int __space, 1284 __u32 mss, __u32 *rcv_wnd, 1285 __u32 *window_clamp, int wscale_ok, 1286 __u8 *rcv_wscale, __u32 init_rcv_wnd); 1287 1288 static inline int tcp_win_from_space(const struct sock *sk, int space) 1289 { 1290 int tcp_adv_win_scale = sock_net(sk)->ipv4.sysctl_tcp_adv_win_scale; 1291 1292 return tcp_adv_win_scale <= 0 ? 1293 (space>>(-tcp_adv_win_scale)) : 1294 space - (space>>tcp_adv_win_scale); 1295 } 1296 1297 /* Note: caller must be prepared to deal with negative returns */ 1298 static inline int tcp_space(const struct sock *sk) 1299 { 1300 return tcp_win_from_space(sk, sk->sk_rcvbuf - 1301 atomic_read(&sk->sk_rmem_alloc)); 1302 } 1303 1304 static inline int tcp_full_space(const struct sock *sk) 1305 { 1306 return tcp_win_from_space(sk, sk->sk_rcvbuf); 1307 } 1308 1309 extern void tcp_openreq_init_rwin(struct request_sock *req, 1310 const struct sock *sk_listener, 1311 const struct dst_entry *dst); 1312 1313 void tcp_enter_memory_pressure(struct sock *sk); 1314 void tcp_leave_memory_pressure(struct sock *sk); 1315 1316 static inline int keepalive_intvl_when(const struct tcp_sock *tp) 1317 { 1318 struct net *net = sock_net((struct sock *)tp); 1319 1320 return tp->keepalive_intvl ? : net->ipv4.sysctl_tcp_keepalive_intvl; 1321 } 1322 1323 static inline int keepalive_time_when(const struct tcp_sock *tp) 1324 { 1325 struct net *net = sock_net((struct sock *)tp); 1326 1327 return tp->keepalive_time ? : net->ipv4.sysctl_tcp_keepalive_time; 1328 } 1329 1330 static inline int keepalive_probes(const struct tcp_sock *tp) 1331 { 1332 struct net *net = sock_net((struct sock *)tp); 1333 1334 return tp->keepalive_probes ? : net->ipv4.sysctl_tcp_keepalive_probes; 1335 } 1336 1337 static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp) 1338 { 1339 const struct inet_connection_sock *icsk = &tp->inet_conn; 1340 1341 return min_t(u32, tcp_jiffies32 - icsk->icsk_ack.lrcvtime, 1342 tcp_jiffies32 - tp->rcv_tstamp); 1343 } 1344 1345 static inline int tcp_fin_time(const struct sock *sk) 1346 { 1347 int fin_timeout = tcp_sk(sk)->linger2 ? : sock_net(sk)->ipv4.sysctl_tcp_fin_timeout; 1348 const int rto = inet_csk(sk)->icsk_rto; 1349 1350 if (fin_timeout < (rto << 2) - (rto >> 1)) 1351 fin_timeout = (rto << 2) - (rto >> 1); 1352 1353 return fin_timeout; 1354 } 1355 1356 static inline bool tcp_paws_check(const struct tcp_options_received *rx_opt, 1357 int paws_win) 1358 { 1359 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win) 1360 return true; 1361 if (unlikely(get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS)) 1362 return true; 1363 /* 1364 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0, 1365 * then following tcp messages have valid values. Ignore 0 value, 1366 * or else 'negative' tsval might forbid us to accept their packets. 1367 */ 1368 if (!rx_opt->ts_recent) 1369 return true; 1370 return false; 1371 } 1372 1373 static inline bool tcp_paws_reject(const struct tcp_options_received *rx_opt, 1374 int rst) 1375 { 1376 if (tcp_paws_check(rx_opt, 0)) 1377 return false; 1378 1379 /* RST segments are not recommended to carry timestamp, 1380 and, if they do, it is recommended to ignore PAWS because 1381 "their cleanup function should take precedence over timestamps." 1382 Certainly, it is mistake. It is necessary to understand the reasons 1383 of this constraint to relax it: if peer reboots, clock may go 1384 out-of-sync and half-open connections will not be reset. 1385 Actually, the problem would be not existing if all 1386 the implementations followed draft about maintaining clock 1387 via reboots. Linux-2.2 DOES NOT! 1388 1389 However, we can relax time bounds for RST segments to MSL. 1390 */ 1391 if (rst && get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_MSL) 1392 return false; 1393 return true; 1394 } 1395 1396 bool tcp_oow_rate_limited(struct net *net, const struct sk_buff *skb, 1397 int mib_idx, u32 *last_oow_ack_time); 1398 1399 static inline void tcp_mib_init(struct net *net) 1400 { 1401 /* See RFC 2012 */ 1402 TCP_ADD_STATS(net, TCP_MIB_RTOALGORITHM, 1); 1403 TCP_ADD_STATS(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ); 1404 TCP_ADD_STATS(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ); 1405 TCP_ADD_STATS(net, TCP_MIB_MAXCONN, -1); 1406 } 1407 1408 /* from STCP */ 1409 static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp) 1410 { 1411 tp->lost_skb_hint = NULL; 1412 } 1413 1414 static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp) 1415 { 1416 tcp_clear_retrans_hints_partial(tp); 1417 tp->retransmit_skb_hint = NULL; 1418 } 1419 1420 union tcp_md5_addr { 1421 struct in_addr a4; 1422 #if IS_ENABLED(CONFIG_IPV6) 1423 struct in6_addr a6; 1424 #endif 1425 }; 1426 1427 /* - key database */ 1428 struct tcp_md5sig_key { 1429 struct hlist_node node; 1430 u8 keylen; 1431 u8 family; /* AF_INET or AF_INET6 */ 1432 union tcp_md5_addr addr; 1433 u8 prefixlen; 1434 u8 key[TCP_MD5SIG_MAXKEYLEN]; 1435 struct rcu_head rcu; 1436 }; 1437 1438 /* - sock block */ 1439 struct tcp_md5sig_info { 1440 struct hlist_head head; 1441 struct rcu_head rcu; 1442 }; 1443 1444 /* - pseudo header */ 1445 struct tcp4_pseudohdr { 1446 __be32 saddr; 1447 __be32 daddr; 1448 __u8 pad; 1449 __u8 protocol; 1450 __be16 len; 1451 }; 1452 1453 struct tcp6_pseudohdr { 1454 struct in6_addr saddr; 1455 struct in6_addr daddr; 1456 __be32 len; 1457 __be32 protocol; /* including padding */ 1458 }; 1459 1460 union tcp_md5sum_block { 1461 struct tcp4_pseudohdr ip4; 1462 #if IS_ENABLED(CONFIG_IPV6) 1463 struct tcp6_pseudohdr ip6; 1464 #endif 1465 }; 1466 1467 /* - pool: digest algorithm, hash description and scratch buffer */ 1468 struct tcp_md5sig_pool { 1469 struct ahash_request *md5_req; 1470 void *scratch; 1471 }; 1472 1473 /* - functions */ 1474 int tcp_v4_md5_hash_skb(char *md5_hash, const struct tcp_md5sig_key *key, 1475 const struct sock *sk, const struct sk_buff *skb); 1476 int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr, 1477 int family, u8 prefixlen, const u8 *newkey, u8 newkeylen, 1478 gfp_t gfp); 1479 int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr, 1480 int family, u8 prefixlen); 1481 struct tcp_md5sig_key *tcp_v4_md5_lookup(const struct sock *sk, 1482 const struct sock *addr_sk); 1483 1484 #ifdef CONFIG_TCP_MD5SIG 1485 struct tcp_md5sig_key *tcp_md5_do_lookup(const struct sock *sk, 1486 const union tcp_md5_addr *addr, 1487 int family); 1488 #define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key) 1489 #else 1490 static inline struct tcp_md5sig_key *tcp_md5_do_lookup(const struct sock *sk, 1491 const union tcp_md5_addr *addr, 1492 int family) 1493 { 1494 return NULL; 1495 } 1496 #define tcp_twsk_md5_key(twsk) NULL 1497 #endif 1498 1499 bool tcp_alloc_md5sig_pool(void); 1500 1501 struct tcp_md5sig_pool *tcp_get_md5sig_pool(void); 1502 static inline void tcp_put_md5sig_pool(void) 1503 { 1504 local_bh_enable(); 1505 } 1506 1507 int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *, 1508 unsigned int header_len); 1509 int tcp_md5_hash_key(struct tcp_md5sig_pool *hp, 1510 const struct tcp_md5sig_key *key); 1511 1512 /* From tcp_fastopen.c */ 1513 void tcp_fastopen_cache_get(struct sock *sk, u16 *mss, 1514 struct tcp_fastopen_cookie *cookie); 1515 void tcp_fastopen_cache_set(struct sock *sk, u16 mss, 1516 struct tcp_fastopen_cookie *cookie, bool syn_lost, 1517 u16 try_exp); 1518 struct tcp_fastopen_request { 1519 /* Fast Open cookie. Size 0 means a cookie request */ 1520 struct tcp_fastopen_cookie cookie; 1521 struct msghdr *data; /* data in MSG_FASTOPEN */ 1522 size_t size; 1523 int copied; /* queued in tcp_connect() */ 1524 }; 1525 void tcp_free_fastopen_req(struct tcp_sock *tp); 1526 void tcp_fastopen_destroy_cipher(struct sock *sk); 1527 void tcp_fastopen_ctx_destroy(struct net *net); 1528 int tcp_fastopen_reset_cipher(struct net *net, struct sock *sk, 1529 void *key, unsigned int len); 1530 void tcp_fastopen_add_skb(struct sock *sk, struct sk_buff *skb); 1531 struct sock *tcp_try_fastopen(struct sock *sk, struct sk_buff *skb, 1532 struct request_sock *req, 1533 struct tcp_fastopen_cookie *foc, 1534 const struct dst_entry *dst); 1535 void tcp_fastopen_init_key_once(struct net *net); 1536 bool tcp_fastopen_cookie_check(struct sock *sk, u16 *mss, 1537 struct tcp_fastopen_cookie *cookie); 1538 bool tcp_fastopen_defer_connect(struct sock *sk, int *err); 1539 #define TCP_FASTOPEN_KEY_LENGTH 16 1540 1541 /* Fastopen key context */ 1542 struct tcp_fastopen_context { 1543 struct crypto_cipher *tfm; 1544 __u8 key[TCP_FASTOPEN_KEY_LENGTH]; 1545 struct rcu_head rcu; 1546 }; 1547 1548 extern unsigned int sysctl_tcp_fastopen_blackhole_timeout; 1549 void tcp_fastopen_active_disable(struct sock *sk); 1550 bool tcp_fastopen_active_should_disable(struct sock *sk); 1551 void tcp_fastopen_active_disable_ofo_check(struct sock *sk); 1552 void tcp_fastopen_active_detect_blackhole(struct sock *sk, bool expired); 1553 1554 /* Latencies incurred by various limits for a sender. They are 1555 * chronograph-like stats that are mutually exclusive. 1556 */ 1557 enum tcp_chrono { 1558 TCP_CHRONO_UNSPEC, 1559 TCP_CHRONO_BUSY, /* Actively sending data (non-empty write queue) */ 1560 TCP_CHRONO_RWND_LIMITED, /* Stalled by insufficient receive window */ 1561 TCP_CHRONO_SNDBUF_LIMITED, /* Stalled by insufficient send buffer */ 1562 __TCP_CHRONO_MAX, 1563 }; 1564 1565 void tcp_chrono_start(struct sock *sk, const enum tcp_chrono type); 1566 void tcp_chrono_stop(struct sock *sk, const enum tcp_chrono type); 1567 1568 /* This helper is needed, because skb->tcp_tsorted_anchor uses 1569 * the same memory storage than skb->destructor/_skb_refdst 1570 */ 1571 static inline void tcp_skb_tsorted_anchor_cleanup(struct sk_buff *skb) 1572 { 1573 skb->destructor = NULL; 1574 skb->_skb_refdst = 0UL; 1575 } 1576 1577 #define tcp_skb_tsorted_save(skb) { \ 1578 unsigned long _save = skb->_skb_refdst; \ 1579 skb->_skb_refdst = 0UL; 1580 1581 #define tcp_skb_tsorted_restore(skb) \ 1582 skb->_skb_refdst = _save; \ 1583 } 1584 1585 void tcp_write_queue_purge(struct sock *sk); 1586 1587 static inline struct sk_buff *tcp_rtx_queue_head(const struct sock *sk) 1588 { 1589 return skb_rb_first(&sk->tcp_rtx_queue); 1590 } 1591 1592 static inline struct sk_buff *tcp_write_queue_head(const struct sock *sk) 1593 { 1594 return skb_peek(&sk->sk_write_queue); 1595 } 1596 1597 static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk) 1598 { 1599 return skb_peek_tail(&sk->sk_write_queue); 1600 } 1601 1602 #define tcp_for_write_queue_from_safe(skb, tmp, sk) \ 1603 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp) 1604 1605 static inline struct sk_buff *tcp_send_head(const struct sock *sk) 1606 { 1607 return skb_peek(&sk->sk_write_queue); 1608 } 1609 1610 static inline bool tcp_skb_is_last(const struct sock *sk, 1611 const struct sk_buff *skb) 1612 { 1613 return skb_queue_is_last(&sk->sk_write_queue, skb); 1614 } 1615 1616 static inline bool tcp_write_queue_empty(const struct sock *sk) 1617 { 1618 return skb_queue_empty(&sk->sk_write_queue); 1619 } 1620 1621 static inline bool tcp_rtx_queue_empty(const struct sock *sk) 1622 { 1623 return RB_EMPTY_ROOT(&sk->tcp_rtx_queue); 1624 } 1625 1626 static inline bool tcp_rtx_and_write_queues_empty(const struct sock *sk) 1627 { 1628 return tcp_rtx_queue_empty(sk) && tcp_write_queue_empty(sk); 1629 } 1630 1631 static inline void tcp_check_send_head(struct sock *sk, struct sk_buff *skb_unlinked) 1632 { 1633 if (tcp_write_queue_empty(sk)) 1634 tcp_chrono_stop(sk, TCP_CHRONO_BUSY); 1635 } 1636 1637 static inline void __tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb) 1638 { 1639 __skb_queue_tail(&sk->sk_write_queue, skb); 1640 } 1641 1642 static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb) 1643 { 1644 __tcp_add_write_queue_tail(sk, skb); 1645 1646 /* Queue it, remembering where we must start sending. */ 1647 if (sk->sk_write_queue.next == skb) 1648 tcp_chrono_start(sk, TCP_CHRONO_BUSY); 1649 } 1650 1651 /* Insert new before skb on the write queue of sk. */ 1652 static inline void tcp_insert_write_queue_before(struct sk_buff *new, 1653 struct sk_buff *skb, 1654 struct sock *sk) 1655 { 1656 __skb_queue_before(&sk->sk_write_queue, skb, new); 1657 } 1658 1659 static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk) 1660 { 1661 tcp_skb_tsorted_anchor_cleanup(skb); 1662 __skb_unlink(skb, &sk->sk_write_queue); 1663 } 1664 1665 void tcp_rbtree_insert(struct rb_root *root, struct sk_buff *skb); 1666 1667 static inline void tcp_rtx_queue_unlink(struct sk_buff *skb, struct sock *sk) 1668 { 1669 tcp_skb_tsorted_anchor_cleanup(skb); 1670 rb_erase(&skb->rbnode, &sk->tcp_rtx_queue); 1671 } 1672 1673 static inline void tcp_rtx_queue_unlink_and_free(struct sk_buff *skb, struct sock *sk) 1674 { 1675 list_del(&skb->tcp_tsorted_anchor); 1676 tcp_rtx_queue_unlink(skb, sk); 1677 sk_wmem_free_skb(sk, skb); 1678 } 1679 1680 static inline void tcp_push_pending_frames(struct sock *sk) 1681 { 1682 if (tcp_send_head(sk)) { 1683 struct tcp_sock *tp = tcp_sk(sk); 1684 1685 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle); 1686 } 1687 } 1688 1689 /* Start sequence of the skb just after the highest skb with SACKed 1690 * bit, valid only if sacked_out > 0 or when the caller has ensured 1691 * validity by itself. 1692 */ 1693 static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp) 1694 { 1695 if (!tp->sacked_out) 1696 return tp->snd_una; 1697 1698 if (tp->highest_sack == NULL) 1699 return tp->snd_nxt; 1700 1701 return TCP_SKB_CB(tp->highest_sack)->seq; 1702 } 1703 1704 static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb) 1705 { 1706 tcp_sk(sk)->highest_sack = skb_rb_next(skb); 1707 } 1708 1709 static inline struct sk_buff *tcp_highest_sack(struct sock *sk) 1710 { 1711 return tcp_sk(sk)->highest_sack; 1712 } 1713 1714 static inline void tcp_highest_sack_reset(struct sock *sk) 1715 { 1716 tcp_sk(sk)->highest_sack = tcp_rtx_queue_head(sk); 1717 } 1718 1719 /* Called when old skb is about to be deleted and replaced by new skb */ 1720 static inline void tcp_highest_sack_replace(struct sock *sk, 1721 struct sk_buff *old, 1722 struct sk_buff *new) 1723 { 1724 if (old == tcp_highest_sack(sk)) 1725 tcp_sk(sk)->highest_sack = new; 1726 } 1727 1728 /* This helper checks if socket has IP_TRANSPARENT set */ 1729 static inline bool inet_sk_transparent(const struct sock *sk) 1730 { 1731 switch (sk->sk_state) { 1732 case TCP_TIME_WAIT: 1733 return inet_twsk(sk)->tw_transparent; 1734 case TCP_NEW_SYN_RECV: 1735 return inet_rsk(inet_reqsk(sk))->no_srccheck; 1736 } 1737 return inet_sk(sk)->transparent; 1738 } 1739 1740 /* Determines whether this is a thin stream (which may suffer from 1741 * increased latency). Used to trigger latency-reducing mechanisms. 1742 */ 1743 static inline bool tcp_stream_is_thin(struct tcp_sock *tp) 1744 { 1745 return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp); 1746 } 1747 1748 /* /proc */ 1749 enum tcp_seq_states { 1750 TCP_SEQ_STATE_LISTENING, 1751 TCP_SEQ_STATE_ESTABLISHED, 1752 }; 1753 1754 int tcp_seq_open(struct inode *inode, struct file *file); 1755 1756 struct tcp_seq_afinfo { 1757 char *name; 1758 sa_family_t family; 1759 const struct file_operations *seq_fops; 1760 struct seq_operations seq_ops; 1761 }; 1762 1763 struct tcp_iter_state { 1764 struct seq_net_private p; 1765 sa_family_t family; 1766 enum tcp_seq_states state; 1767 struct sock *syn_wait_sk; 1768 int bucket, offset, sbucket, num; 1769 loff_t last_pos; 1770 }; 1771 1772 int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo); 1773 void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo); 1774 1775 extern struct request_sock_ops tcp_request_sock_ops; 1776 extern struct request_sock_ops tcp6_request_sock_ops; 1777 1778 void tcp_v4_destroy_sock(struct sock *sk); 1779 1780 struct sk_buff *tcp_gso_segment(struct sk_buff *skb, 1781 netdev_features_t features); 1782 struct sk_buff **tcp_gro_receive(struct sk_buff **head, struct sk_buff *skb); 1783 int tcp_gro_complete(struct sk_buff *skb); 1784 1785 void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr, __be32 daddr); 1786 1787 static inline u32 tcp_notsent_lowat(const struct tcp_sock *tp) 1788 { 1789 struct net *net = sock_net((struct sock *)tp); 1790 return tp->notsent_lowat ?: net->ipv4.sysctl_tcp_notsent_lowat; 1791 } 1792 1793 static inline bool tcp_stream_memory_free(const struct sock *sk) 1794 { 1795 const struct tcp_sock *tp = tcp_sk(sk); 1796 u32 notsent_bytes = tp->write_seq - tp->snd_nxt; 1797 1798 return notsent_bytes < tcp_notsent_lowat(tp); 1799 } 1800 1801 #ifdef CONFIG_PROC_FS 1802 int tcp4_proc_init(void); 1803 void tcp4_proc_exit(void); 1804 #endif 1805 1806 int tcp_rtx_synack(const struct sock *sk, struct request_sock *req); 1807 int tcp_conn_request(struct request_sock_ops *rsk_ops, 1808 const struct tcp_request_sock_ops *af_ops, 1809 struct sock *sk, struct sk_buff *skb); 1810 1811 /* TCP af-specific functions */ 1812 struct tcp_sock_af_ops { 1813 #ifdef CONFIG_TCP_MD5SIG 1814 struct tcp_md5sig_key *(*md5_lookup) (const struct sock *sk, 1815 const struct sock *addr_sk); 1816 int (*calc_md5_hash)(char *location, 1817 const struct tcp_md5sig_key *md5, 1818 const struct sock *sk, 1819 const struct sk_buff *skb); 1820 int (*md5_parse)(struct sock *sk, 1821 int optname, 1822 char __user *optval, 1823 int optlen); 1824 #endif 1825 }; 1826 1827 struct tcp_request_sock_ops { 1828 u16 mss_clamp; 1829 #ifdef CONFIG_TCP_MD5SIG 1830 struct tcp_md5sig_key *(*req_md5_lookup)(const struct sock *sk, 1831 const struct sock *addr_sk); 1832 int (*calc_md5_hash) (char *location, 1833 const struct tcp_md5sig_key *md5, 1834 const struct sock *sk, 1835 const struct sk_buff *skb); 1836 #endif 1837 void (*init_req)(struct request_sock *req, 1838 const struct sock *sk_listener, 1839 struct sk_buff *skb); 1840 #ifdef CONFIG_SYN_COOKIES 1841 __u32 (*cookie_init_seq)(const struct sk_buff *skb, 1842 __u16 *mss); 1843 #endif 1844 struct dst_entry *(*route_req)(const struct sock *sk, struct flowi *fl, 1845 const struct request_sock *req); 1846 u32 (*init_seq)(const struct sk_buff *skb); 1847 u32 (*init_ts_off)(const struct net *net, const struct sk_buff *skb); 1848 int (*send_synack)(const struct sock *sk, struct dst_entry *dst, 1849 struct flowi *fl, struct request_sock *req, 1850 struct tcp_fastopen_cookie *foc, 1851 enum tcp_synack_type synack_type); 1852 }; 1853 1854 #ifdef CONFIG_SYN_COOKIES 1855 static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops, 1856 const struct sock *sk, struct sk_buff *skb, 1857 __u16 *mss) 1858 { 1859 tcp_synq_overflow(sk); 1860 __NET_INC_STATS(sock_net(sk), LINUX_MIB_SYNCOOKIESSENT); 1861 return ops->cookie_init_seq(skb, mss); 1862 } 1863 #else 1864 static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops, 1865 const struct sock *sk, struct sk_buff *skb, 1866 __u16 *mss) 1867 { 1868 return 0; 1869 } 1870 #endif 1871 1872 int tcpv4_offload_init(void); 1873 1874 void tcp_v4_init(void); 1875 void tcp_init(void); 1876 1877 /* tcp_recovery.c */ 1878 extern void tcp_rack_mark_lost(struct sock *sk); 1879 extern void tcp_rack_advance(struct tcp_sock *tp, u8 sacked, u32 end_seq, 1880 u64 xmit_time); 1881 extern void tcp_rack_reo_timeout(struct sock *sk); 1882 extern void tcp_rack_update_reo_wnd(struct sock *sk, struct rate_sample *rs); 1883 1884 /* At how many usecs into the future should the RTO fire? */ 1885 static inline s64 tcp_rto_delta_us(const struct sock *sk) 1886 { 1887 const struct sk_buff *skb = tcp_rtx_queue_head(sk); 1888 u32 rto = inet_csk(sk)->icsk_rto; 1889 u64 rto_time_stamp_us = skb->skb_mstamp + jiffies_to_usecs(rto); 1890 1891 return rto_time_stamp_us - tcp_sk(sk)->tcp_mstamp; 1892 } 1893 1894 /* 1895 * Save and compile IPv4 options, return a pointer to it 1896 */ 1897 static inline struct ip_options_rcu *tcp_v4_save_options(struct net *net, 1898 struct sk_buff *skb) 1899 { 1900 const struct ip_options *opt = &TCP_SKB_CB(skb)->header.h4.opt; 1901 struct ip_options_rcu *dopt = NULL; 1902 1903 if (opt->optlen) { 1904 int opt_size = sizeof(*dopt) + opt->optlen; 1905 1906 dopt = kmalloc(opt_size, GFP_ATOMIC); 1907 if (dopt && __ip_options_echo(net, &dopt->opt, skb, opt)) { 1908 kfree(dopt); 1909 dopt = NULL; 1910 } 1911 } 1912 return dopt; 1913 } 1914 1915 /* locally generated TCP pure ACKs have skb->truesize == 2 1916 * (check tcp_send_ack() in net/ipv4/tcp_output.c ) 1917 * This is much faster than dissecting the packet to find out. 1918 * (Think of GRE encapsulations, IPv4, IPv6, ...) 1919 */ 1920 static inline bool skb_is_tcp_pure_ack(const struct sk_buff *skb) 1921 { 1922 return skb->truesize == 2; 1923 } 1924 1925 static inline void skb_set_tcp_pure_ack(struct sk_buff *skb) 1926 { 1927 skb->truesize = 2; 1928 } 1929 1930 static inline int tcp_inq(struct sock *sk) 1931 { 1932 struct tcp_sock *tp = tcp_sk(sk); 1933 int answ; 1934 1935 if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) { 1936 answ = 0; 1937 } else if (sock_flag(sk, SOCK_URGINLINE) || 1938 !tp->urg_data || 1939 before(tp->urg_seq, tp->copied_seq) || 1940 !before(tp->urg_seq, tp->rcv_nxt)) { 1941 1942 answ = tp->rcv_nxt - tp->copied_seq; 1943 1944 /* Subtract 1, if FIN was received */ 1945 if (answ && sock_flag(sk, SOCK_DONE)) 1946 answ--; 1947 } else { 1948 answ = tp->urg_seq - tp->copied_seq; 1949 } 1950 1951 return answ; 1952 } 1953 1954 int tcp_peek_len(struct socket *sock); 1955 1956 static inline void tcp_segs_in(struct tcp_sock *tp, const struct sk_buff *skb) 1957 { 1958 u16 segs_in; 1959 1960 segs_in = max_t(u16, 1, skb_shinfo(skb)->gso_segs); 1961 tp->segs_in += segs_in; 1962 if (skb->len > tcp_hdrlen(skb)) 1963 tp->data_segs_in += segs_in; 1964 } 1965 1966 /* 1967 * TCP listen path runs lockless. 1968 * We forced "struct sock" to be const qualified to make sure 1969 * we don't modify one of its field by mistake. 1970 * Here, we increment sk_drops which is an atomic_t, so we can safely 1971 * make sock writable again. 1972 */ 1973 static inline void tcp_listendrop(const struct sock *sk) 1974 { 1975 atomic_inc(&((struct sock *)sk)->sk_drops); 1976 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS); 1977 } 1978 1979 enum hrtimer_restart tcp_pace_kick(struct hrtimer *timer); 1980 1981 /* 1982 * Interface for adding Upper Level Protocols over TCP 1983 */ 1984 1985 #define TCP_ULP_NAME_MAX 16 1986 #define TCP_ULP_MAX 128 1987 #define TCP_ULP_BUF_MAX (TCP_ULP_NAME_MAX*TCP_ULP_MAX) 1988 1989 enum { 1990 TCP_ULP_TLS, 1991 TCP_ULP_BPF, 1992 }; 1993 1994 struct tcp_ulp_ops { 1995 struct list_head list; 1996 1997 /* initialize ulp */ 1998 int (*init)(struct sock *sk); 1999 /* cleanup ulp */ 2000 void (*release)(struct sock *sk); 2001 2002 int uid; 2003 char name[TCP_ULP_NAME_MAX]; 2004 bool user_visible; 2005 struct module *owner; 2006 }; 2007 int tcp_register_ulp(struct tcp_ulp_ops *type); 2008 void tcp_unregister_ulp(struct tcp_ulp_ops *type); 2009 int tcp_set_ulp(struct sock *sk, const char *name); 2010 int tcp_set_ulp_id(struct sock *sk, const int ulp); 2011 void tcp_get_available_ulp(char *buf, size_t len); 2012 void tcp_cleanup_ulp(struct sock *sk); 2013 2014 /* Call BPF_SOCK_OPS program that returns an int. If the return value 2015 * is < 0, then the BPF op failed (for example if the loaded BPF 2016 * program does not support the chosen operation or there is no BPF 2017 * program loaded). 2018 */ 2019 #ifdef CONFIG_BPF 2020 static inline int tcp_call_bpf(struct sock *sk, int op, u32 nargs, u32 *args) 2021 { 2022 struct bpf_sock_ops_kern sock_ops; 2023 int ret; 2024 2025 memset(&sock_ops, 0, offsetof(struct bpf_sock_ops_kern, temp)); 2026 if (sk_fullsock(sk)) { 2027 sock_ops.is_fullsock = 1; 2028 sock_owned_by_me(sk); 2029 } 2030 2031 sock_ops.sk = sk; 2032 sock_ops.op = op; 2033 if (nargs > 0) 2034 memcpy(sock_ops.args, args, nargs * sizeof(*args)); 2035 2036 ret = BPF_CGROUP_RUN_PROG_SOCK_OPS(&sock_ops); 2037 if (ret == 0) 2038 ret = sock_ops.reply; 2039 else 2040 ret = -1; 2041 return ret; 2042 } 2043 2044 static inline int tcp_call_bpf_2arg(struct sock *sk, int op, u32 arg1, u32 arg2) 2045 { 2046 u32 args[2] = {arg1, arg2}; 2047 2048 return tcp_call_bpf(sk, op, 2, args); 2049 } 2050 2051 static inline int tcp_call_bpf_3arg(struct sock *sk, int op, u32 arg1, u32 arg2, 2052 u32 arg3) 2053 { 2054 u32 args[3] = {arg1, arg2, arg3}; 2055 2056 return tcp_call_bpf(sk, op, 3, args); 2057 } 2058 2059 #else 2060 static inline int tcp_call_bpf(struct sock *sk, int op, u32 nargs, u32 *args) 2061 { 2062 return -EPERM; 2063 } 2064 2065 static inline int tcp_call_bpf_2arg(struct sock *sk, int op, u32 arg1, u32 arg2) 2066 { 2067 return -EPERM; 2068 } 2069 2070 static inline int tcp_call_bpf_3arg(struct sock *sk, int op, u32 arg1, u32 arg2, 2071 u32 arg3) 2072 { 2073 return -EPERM; 2074 } 2075 2076 #endif 2077 2078 static inline u32 tcp_timeout_init(struct sock *sk) 2079 { 2080 int timeout; 2081 2082 timeout = tcp_call_bpf(sk, BPF_SOCK_OPS_TIMEOUT_INIT, 0, NULL); 2083 2084 if (timeout <= 0) 2085 timeout = TCP_TIMEOUT_INIT; 2086 return timeout; 2087 } 2088 2089 static inline u32 tcp_rwnd_init_bpf(struct sock *sk) 2090 { 2091 int rwnd; 2092 2093 rwnd = tcp_call_bpf(sk, BPF_SOCK_OPS_RWND_INIT, 0, NULL); 2094 2095 if (rwnd < 0) 2096 rwnd = 0; 2097 return rwnd; 2098 } 2099 2100 static inline bool tcp_bpf_ca_needs_ecn(struct sock *sk) 2101 { 2102 return (tcp_call_bpf(sk, BPF_SOCK_OPS_NEEDS_ECN, 0, NULL) == 1); 2103 } 2104 2105 #if IS_ENABLED(CONFIG_SMC) 2106 extern struct static_key_false tcp_have_smc; 2107 #endif 2108 #endif /* _TCP_H */ 2109