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 #define TCP_RACK_NO_DUPTHRESH 0x4 /* Do not use DUPACK threshold in RACK */ 249 250 extern atomic_long_t tcp_memory_allocated; 251 extern struct percpu_counter tcp_sockets_allocated; 252 extern unsigned long tcp_memory_pressure; 253 254 /* optimized version of sk_under_memory_pressure() for TCP sockets */ 255 static inline bool tcp_under_memory_pressure(const struct sock *sk) 256 { 257 if (mem_cgroup_sockets_enabled && sk->sk_memcg && 258 mem_cgroup_under_socket_pressure(sk->sk_memcg)) 259 return true; 260 261 return tcp_memory_pressure; 262 } 263 /* 264 * The next routines deal with comparing 32 bit unsigned ints 265 * and worry about wraparound (automatic with unsigned arithmetic). 266 */ 267 268 static inline bool before(__u32 seq1, __u32 seq2) 269 { 270 return (__s32)(seq1-seq2) < 0; 271 } 272 #define after(seq2, seq1) before(seq1, seq2) 273 274 /* is s2<=s1<=s3 ? */ 275 static inline bool between(__u32 seq1, __u32 seq2, __u32 seq3) 276 { 277 return seq3 - seq2 >= seq1 - seq2; 278 } 279 280 static inline bool tcp_out_of_memory(struct sock *sk) 281 { 282 if (sk->sk_wmem_queued > SOCK_MIN_SNDBUF && 283 sk_memory_allocated(sk) > sk_prot_mem_limits(sk, 2)) 284 return true; 285 return false; 286 } 287 288 void sk_forced_mem_schedule(struct sock *sk, int size); 289 290 static inline bool tcp_too_many_orphans(struct sock *sk, int shift) 291 { 292 struct percpu_counter *ocp = sk->sk_prot->orphan_count; 293 int orphans = percpu_counter_read_positive(ocp); 294 295 if (orphans << shift > sysctl_tcp_max_orphans) { 296 orphans = percpu_counter_sum_positive(ocp); 297 if (orphans << shift > sysctl_tcp_max_orphans) 298 return true; 299 } 300 return false; 301 } 302 303 bool tcp_check_oom(struct sock *sk, int shift); 304 305 306 extern struct proto tcp_prot; 307 308 #define TCP_INC_STATS(net, field) SNMP_INC_STATS((net)->mib.tcp_statistics, field) 309 #define __TCP_INC_STATS(net, field) __SNMP_INC_STATS((net)->mib.tcp_statistics, field) 310 #define TCP_DEC_STATS(net, field) SNMP_DEC_STATS((net)->mib.tcp_statistics, field) 311 #define TCP_ADD_STATS(net, field, val) SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val) 312 313 void tcp_tasklet_init(void); 314 315 void tcp_v4_err(struct sk_buff *skb, u32); 316 317 void tcp_shutdown(struct sock *sk, int how); 318 319 int tcp_v4_early_demux(struct sk_buff *skb); 320 int tcp_v4_rcv(struct sk_buff *skb); 321 322 int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw); 323 int tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size); 324 int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size); 325 int tcp_sendpage(struct sock *sk, struct page *page, int offset, size_t size, 326 int flags); 327 int tcp_sendpage_locked(struct sock *sk, struct page *page, int offset, 328 size_t size, int flags); 329 ssize_t do_tcp_sendpages(struct sock *sk, struct page *page, int offset, 330 size_t size, int flags); 331 void tcp_release_cb(struct sock *sk); 332 void tcp_wfree(struct sk_buff *skb); 333 void tcp_write_timer_handler(struct sock *sk); 334 void tcp_delack_timer_handler(struct sock *sk); 335 int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg); 336 int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb); 337 void tcp_rcv_established(struct sock *sk, struct sk_buff *skb); 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 if (hrtimer_try_to_cancel(&tcp_sk(sk)->pacing_timer) == 1) 561 __sock_put(sk); 562 563 if (hrtimer_try_to_cancel(&tcp_sk(sk)->compressed_ack_timer) == 1) 564 __sock_put(sk); 565 566 inet_csk_clear_xmit_timers(sk); 567 } 568 569 unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu); 570 unsigned int tcp_current_mss(struct sock *sk); 571 572 /* Bound MSS / TSO packet size with the half of the window */ 573 static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize) 574 { 575 int cutoff; 576 577 /* When peer uses tiny windows, there is no use in packetizing 578 * to sub-MSS pieces for the sake of SWS or making sure there 579 * are enough packets in the pipe for fast recovery. 580 * 581 * On the other hand, for extremely large MSS devices, handling 582 * smaller than MSS windows in this way does make sense. 583 */ 584 if (tp->max_window > TCP_MSS_DEFAULT) 585 cutoff = (tp->max_window >> 1); 586 else 587 cutoff = tp->max_window; 588 589 if (cutoff && pktsize > cutoff) 590 return max_t(int, cutoff, 68U - tp->tcp_header_len); 591 else 592 return pktsize; 593 } 594 595 /* tcp.c */ 596 void tcp_get_info(struct sock *, struct tcp_info *); 597 598 /* Read 'sendfile()'-style from a TCP socket */ 599 int tcp_read_sock(struct sock *sk, read_descriptor_t *desc, 600 sk_read_actor_t recv_actor); 601 602 void tcp_initialize_rcv_mss(struct sock *sk); 603 604 int tcp_mtu_to_mss(struct sock *sk, int pmtu); 605 int tcp_mss_to_mtu(struct sock *sk, int mss); 606 void tcp_mtup_init(struct sock *sk); 607 void tcp_init_buffer_space(struct sock *sk); 608 609 static inline void tcp_bound_rto(const struct sock *sk) 610 { 611 if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX) 612 inet_csk(sk)->icsk_rto = TCP_RTO_MAX; 613 } 614 615 static inline u32 __tcp_set_rto(const struct tcp_sock *tp) 616 { 617 return usecs_to_jiffies((tp->srtt_us >> 3) + tp->rttvar_us); 618 } 619 620 static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd) 621 { 622 tp->pred_flags = htonl((tp->tcp_header_len << 26) | 623 ntohl(TCP_FLAG_ACK) | 624 snd_wnd); 625 } 626 627 static inline void tcp_fast_path_on(struct tcp_sock *tp) 628 { 629 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale); 630 } 631 632 static inline void tcp_fast_path_check(struct sock *sk) 633 { 634 struct tcp_sock *tp = tcp_sk(sk); 635 636 if (RB_EMPTY_ROOT(&tp->out_of_order_queue) && 637 tp->rcv_wnd && 638 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf && 639 !tp->urg_data) 640 tcp_fast_path_on(tp); 641 } 642 643 /* Compute the actual rto_min value */ 644 static inline u32 tcp_rto_min(struct sock *sk) 645 { 646 const struct dst_entry *dst = __sk_dst_get(sk); 647 u32 rto_min = TCP_RTO_MIN; 648 649 if (dst && dst_metric_locked(dst, RTAX_RTO_MIN)) 650 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN); 651 return rto_min; 652 } 653 654 static inline u32 tcp_rto_min_us(struct sock *sk) 655 { 656 return jiffies_to_usecs(tcp_rto_min(sk)); 657 } 658 659 static inline bool tcp_ca_dst_locked(const struct dst_entry *dst) 660 { 661 return dst_metric_locked(dst, RTAX_CC_ALGO); 662 } 663 664 /* Minimum RTT in usec. ~0 means not available. */ 665 static inline u32 tcp_min_rtt(const struct tcp_sock *tp) 666 { 667 return minmax_get(&tp->rtt_min); 668 } 669 670 /* Compute the actual receive window we are currently advertising. 671 * Rcv_nxt can be after the window if our peer push more data 672 * than the offered window. 673 */ 674 static inline u32 tcp_receive_window(const struct tcp_sock *tp) 675 { 676 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt; 677 678 if (win < 0) 679 win = 0; 680 return (u32) win; 681 } 682 683 /* Choose a new window, without checks for shrinking, and without 684 * scaling applied to the result. The caller does these things 685 * if necessary. This is a "raw" window selection. 686 */ 687 u32 __tcp_select_window(struct sock *sk); 688 689 void tcp_send_window_probe(struct sock *sk); 690 691 /* TCP uses 32bit jiffies to save some space. 692 * Note that this is different from tcp_time_stamp, which 693 * historically has been the same until linux-4.13. 694 */ 695 #define tcp_jiffies32 ((u32)jiffies) 696 697 /* 698 * Deliver a 32bit value for TCP timestamp option (RFC 7323) 699 * It is no longer tied to jiffies, but to 1 ms clock. 700 * Note: double check if you want to use tcp_jiffies32 instead of this. 701 */ 702 #define TCP_TS_HZ 1000 703 704 static inline u64 tcp_clock_ns(void) 705 { 706 return local_clock(); 707 } 708 709 static inline u64 tcp_clock_us(void) 710 { 711 return div_u64(tcp_clock_ns(), NSEC_PER_USEC); 712 } 713 714 /* This should only be used in contexts where tp->tcp_mstamp is up to date */ 715 static inline u32 tcp_time_stamp(const struct tcp_sock *tp) 716 { 717 return div_u64(tp->tcp_mstamp, USEC_PER_SEC / TCP_TS_HZ); 718 } 719 720 /* Could use tcp_clock_us() / 1000, but this version uses a single divide */ 721 static inline u32 tcp_time_stamp_raw(void) 722 { 723 return div_u64(tcp_clock_ns(), NSEC_PER_SEC / TCP_TS_HZ); 724 } 725 726 727 /* Refresh 1us clock of a TCP socket, 728 * ensuring monotically increasing values. 729 */ 730 static inline void tcp_mstamp_refresh(struct tcp_sock *tp) 731 { 732 u64 val = tcp_clock_us(); 733 734 if (val > tp->tcp_mstamp) 735 tp->tcp_mstamp = val; 736 } 737 738 static inline u32 tcp_stamp_us_delta(u64 t1, u64 t0) 739 { 740 return max_t(s64, t1 - t0, 0); 741 } 742 743 static inline u32 tcp_skb_timestamp(const struct sk_buff *skb) 744 { 745 return div_u64(skb->skb_mstamp, USEC_PER_SEC / TCP_TS_HZ); 746 } 747 748 749 #define tcp_flag_byte(th) (((u_int8_t *)th)[13]) 750 751 #define TCPHDR_FIN 0x01 752 #define TCPHDR_SYN 0x02 753 #define TCPHDR_RST 0x04 754 #define TCPHDR_PSH 0x08 755 #define TCPHDR_ACK 0x10 756 #define TCPHDR_URG 0x20 757 #define TCPHDR_ECE 0x40 758 #define TCPHDR_CWR 0x80 759 760 #define TCPHDR_SYN_ECN (TCPHDR_SYN | TCPHDR_ECE | TCPHDR_CWR) 761 762 /* This is what the send packet queuing engine uses to pass 763 * TCP per-packet control information to the transmission code. 764 * We also store the host-order sequence numbers in here too. 765 * This is 44 bytes if IPV6 is enabled. 766 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately. 767 */ 768 struct tcp_skb_cb { 769 __u32 seq; /* Starting sequence number */ 770 __u32 end_seq; /* SEQ + FIN + SYN + datalen */ 771 union { 772 /* Note : tcp_tw_isn is used in input path only 773 * (isn chosen by tcp_timewait_state_process()) 774 * 775 * tcp_gso_segs/size are used in write queue only, 776 * cf tcp_skb_pcount()/tcp_skb_mss() 777 */ 778 __u32 tcp_tw_isn; 779 struct { 780 u16 tcp_gso_segs; 781 u16 tcp_gso_size; 782 }; 783 }; 784 __u8 tcp_flags; /* TCP header flags. (tcp[13]) */ 785 786 __u8 sacked; /* State flags for SACK. */ 787 #define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */ 788 #define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */ 789 #define TCPCB_LOST 0x04 /* SKB is lost */ 790 #define TCPCB_TAGBITS 0x07 /* All tag bits */ 791 #define TCPCB_REPAIRED 0x10 /* SKB repaired (no skb_mstamp) */ 792 #define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */ 793 #define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS| \ 794 TCPCB_REPAIRED) 795 796 __u8 ip_dsfield; /* IPv4 tos or IPv6 dsfield */ 797 __u8 txstamp_ack:1, /* Record TX timestamp for ack? */ 798 eor:1, /* Is skb MSG_EOR marked? */ 799 has_rxtstamp:1, /* SKB has a RX timestamp */ 800 unused:5; 801 __u32 ack_seq; /* Sequence number ACK'd */ 802 union { 803 struct { 804 /* There is space for up to 24 bytes */ 805 __u32 in_flight:30,/* Bytes in flight at transmit */ 806 is_app_limited:1, /* cwnd not fully used? */ 807 unused:1; 808 /* pkts S/ACKed so far upon tx of skb, incl retrans: */ 809 __u32 delivered; 810 /* start of send pipeline phase */ 811 u64 first_tx_mstamp; 812 /* when we reached the "delivered" count */ 813 u64 delivered_mstamp; 814 } tx; /* only used for outgoing skbs */ 815 union { 816 struct inet_skb_parm h4; 817 #if IS_ENABLED(CONFIG_IPV6) 818 struct inet6_skb_parm h6; 819 #endif 820 } header; /* For incoming skbs */ 821 struct { 822 __u32 flags; 823 struct sock *sk_redir; 824 void *data_end; 825 } bpf; 826 }; 827 }; 828 829 #define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0])) 830 831 832 #if IS_ENABLED(CONFIG_IPV6) 833 /* This is the variant of inet6_iif() that must be used by TCP, 834 * as TCP moves IP6CB into a different location in skb->cb[] 835 */ 836 static inline int tcp_v6_iif(const struct sk_buff *skb) 837 { 838 bool l3_slave = ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags); 839 840 return l3_slave ? skb->skb_iif : TCP_SKB_CB(skb)->header.h6.iif; 841 } 842 843 /* TCP_SKB_CB reference means this can not be used from early demux */ 844 static inline int tcp_v6_sdif(const struct sk_buff *skb) 845 { 846 #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV) 847 if (skb && ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags)) 848 return TCP_SKB_CB(skb)->header.h6.iif; 849 #endif 850 return 0; 851 } 852 #endif 853 854 static inline bool inet_exact_dif_match(struct net *net, struct sk_buff *skb) 855 { 856 #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV) 857 if (!net->ipv4.sysctl_tcp_l3mdev_accept && 858 skb && ipv4_l3mdev_skb(IPCB(skb)->flags)) 859 return true; 860 #endif 861 return false; 862 } 863 864 /* TCP_SKB_CB reference means this can not be used from early demux */ 865 static inline int tcp_v4_sdif(struct sk_buff *skb) 866 { 867 #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV) 868 if (skb && ipv4_l3mdev_skb(TCP_SKB_CB(skb)->header.h4.flags)) 869 return TCP_SKB_CB(skb)->header.h4.iif; 870 #endif 871 return 0; 872 } 873 874 /* Due to TSO, an SKB can be composed of multiple actual 875 * packets. To keep these tracked properly, we use this. 876 */ 877 static inline int tcp_skb_pcount(const struct sk_buff *skb) 878 { 879 return TCP_SKB_CB(skb)->tcp_gso_segs; 880 } 881 882 static inline void tcp_skb_pcount_set(struct sk_buff *skb, int segs) 883 { 884 TCP_SKB_CB(skb)->tcp_gso_segs = segs; 885 } 886 887 static inline void tcp_skb_pcount_add(struct sk_buff *skb, int segs) 888 { 889 TCP_SKB_CB(skb)->tcp_gso_segs += segs; 890 } 891 892 /* This is valid iff skb is in write queue and tcp_skb_pcount() > 1. */ 893 static inline int tcp_skb_mss(const struct sk_buff *skb) 894 { 895 return TCP_SKB_CB(skb)->tcp_gso_size; 896 } 897 898 static inline bool tcp_skb_can_collapse_to(const struct sk_buff *skb) 899 { 900 return likely(!TCP_SKB_CB(skb)->eor); 901 } 902 903 /* Events passed to congestion control interface */ 904 enum tcp_ca_event { 905 CA_EVENT_TX_START, /* first transmit when no packets in flight */ 906 CA_EVENT_CWND_RESTART, /* congestion window restart */ 907 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */ 908 CA_EVENT_LOSS, /* loss timeout */ 909 CA_EVENT_ECN_NO_CE, /* ECT set, but not CE marked */ 910 CA_EVENT_ECN_IS_CE, /* received CE marked IP packet */ 911 CA_EVENT_DELAYED_ACK, /* Delayed ack is sent */ 912 CA_EVENT_NON_DELAYED_ACK, 913 }; 914 915 /* Information about inbound ACK, passed to cong_ops->in_ack_event() */ 916 enum tcp_ca_ack_event_flags { 917 CA_ACK_SLOWPATH = (1 << 0), /* In slow path processing */ 918 CA_ACK_WIN_UPDATE = (1 << 1), /* ACK updated window */ 919 CA_ACK_ECE = (1 << 2), /* ECE bit is set on ack */ 920 }; 921 922 /* 923 * Interface for adding new TCP congestion control handlers 924 */ 925 #define TCP_CA_NAME_MAX 16 926 #define TCP_CA_MAX 128 927 #define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX) 928 929 #define TCP_CA_UNSPEC 0 930 931 /* Algorithm can be set on socket without CAP_NET_ADMIN privileges */ 932 #define TCP_CONG_NON_RESTRICTED 0x1 933 /* Requires ECN/ECT set on all packets */ 934 #define TCP_CONG_NEEDS_ECN 0x2 935 936 union tcp_cc_info; 937 938 struct ack_sample { 939 u32 pkts_acked; 940 s32 rtt_us; 941 u32 in_flight; 942 }; 943 944 /* A rate sample measures the number of (original/retransmitted) data 945 * packets delivered "delivered" over an interval of time "interval_us". 946 * The tcp_rate.c code fills in the rate sample, and congestion 947 * control modules that define a cong_control function to run at the end 948 * of ACK processing can optionally chose to consult this sample when 949 * setting cwnd and pacing rate. 950 * A sample is invalid if "delivered" or "interval_us" is negative. 951 */ 952 struct rate_sample { 953 u64 prior_mstamp; /* starting timestamp for interval */ 954 u32 prior_delivered; /* tp->delivered at "prior_mstamp" */ 955 s32 delivered; /* number of packets delivered over interval */ 956 long interval_us; /* time for tp->delivered to incr "delivered" */ 957 long rtt_us; /* RTT of last (S)ACKed packet (or -1) */ 958 int losses; /* number of packets marked lost upon ACK */ 959 u32 acked_sacked; /* number of packets newly (S)ACKed upon ACK */ 960 u32 prior_in_flight; /* in flight before this ACK */ 961 bool is_app_limited; /* is sample from packet with bubble in pipe? */ 962 bool is_retrans; /* is sample from retransmission? */ 963 bool is_ack_delayed; /* is this (likely) a delayed ACK? */ 964 }; 965 966 struct tcp_congestion_ops { 967 struct list_head list; 968 u32 key; 969 u32 flags; 970 971 /* initialize private data (optional) */ 972 void (*init)(struct sock *sk); 973 /* cleanup private data (optional) */ 974 void (*release)(struct sock *sk); 975 976 /* return slow start threshold (required) */ 977 u32 (*ssthresh)(struct sock *sk); 978 /* do new cwnd calculation (required) */ 979 void (*cong_avoid)(struct sock *sk, u32 ack, u32 acked); 980 /* call before changing ca_state (optional) */ 981 void (*set_state)(struct sock *sk, u8 new_state); 982 /* call when cwnd event occurs (optional) */ 983 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev); 984 /* call when ack arrives (optional) */ 985 void (*in_ack_event)(struct sock *sk, u32 flags); 986 /* new value of cwnd after loss (required) */ 987 u32 (*undo_cwnd)(struct sock *sk); 988 /* hook for packet ack accounting (optional) */ 989 void (*pkts_acked)(struct sock *sk, const struct ack_sample *sample); 990 /* override sysctl_tcp_min_tso_segs */ 991 u32 (*min_tso_segs)(struct sock *sk); 992 /* returns the multiplier used in tcp_sndbuf_expand (optional) */ 993 u32 (*sndbuf_expand)(struct sock *sk); 994 /* call when packets are delivered to update cwnd and pacing rate, 995 * after all the ca_state processing. (optional) 996 */ 997 void (*cong_control)(struct sock *sk, const struct rate_sample *rs); 998 /* get info for inet_diag (optional) */ 999 size_t (*get_info)(struct sock *sk, u32 ext, int *attr, 1000 union tcp_cc_info *info); 1001 1002 char name[TCP_CA_NAME_MAX]; 1003 struct module *owner; 1004 }; 1005 1006 int tcp_register_congestion_control(struct tcp_congestion_ops *type); 1007 void tcp_unregister_congestion_control(struct tcp_congestion_ops *type); 1008 1009 void tcp_assign_congestion_control(struct sock *sk); 1010 void tcp_init_congestion_control(struct sock *sk); 1011 void tcp_cleanup_congestion_control(struct sock *sk); 1012 int tcp_set_default_congestion_control(struct net *net, const char *name); 1013 void tcp_get_default_congestion_control(struct net *net, char *name); 1014 void tcp_get_available_congestion_control(char *buf, size_t len); 1015 void tcp_get_allowed_congestion_control(char *buf, size_t len); 1016 int tcp_set_allowed_congestion_control(char *allowed); 1017 int tcp_set_congestion_control(struct sock *sk, const char *name, bool load, bool reinit); 1018 u32 tcp_slow_start(struct tcp_sock *tp, u32 acked); 1019 void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w, u32 acked); 1020 1021 u32 tcp_reno_ssthresh(struct sock *sk); 1022 u32 tcp_reno_undo_cwnd(struct sock *sk); 1023 void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 acked); 1024 extern struct tcp_congestion_ops tcp_reno; 1025 1026 struct tcp_congestion_ops *tcp_ca_find_key(u32 key); 1027 u32 tcp_ca_get_key_by_name(struct net *net, const char *name, bool *ecn_ca); 1028 #ifdef CONFIG_INET 1029 char *tcp_ca_get_name_by_key(u32 key, char *buffer); 1030 #else 1031 static inline char *tcp_ca_get_name_by_key(u32 key, char *buffer) 1032 { 1033 return NULL; 1034 } 1035 #endif 1036 1037 static inline bool tcp_ca_needs_ecn(const struct sock *sk) 1038 { 1039 const struct inet_connection_sock *icsk = inet_csk(sk); 1040 1041 return icsk->icsk_ca_ops->flags & TCP_CONG_NEEDS_ECN; 1042 } 1043 1044 static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state) 1045 { 1046 struct inet_connection_sock *icsk = inet_csk(sk); 1047 1048 if (icsk->icsk_ca_ops->set_state) 1049 icsk->icsk_ca_ops->set_state(sk, ca_state); 1050 icsk->icsk_ca_state = ca_state; 1051 } 1052 1053 static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event) 1054 { 1055 const struct inet_connection_sock *icsk = inet_csk(sk); 1056 1057 if (icsk->icsk_ca_ops->cwnd_event) 1058 icsk->icsk_ca_ops->cwnd_event(sk, event); 1059 } 1060 1061 /* From tcp_rate.c */ 1062 void tcp_rate_skb_sent(struct sock *sk, struct sk_buff *skb); 1063 void tcp_rate_skb_delivered(struct sock *sk, struct sk_buff *skb, 1064 struct rate_sample *rs); 1065 void tcp_rate_gen(struct sock *sk, u32 delivered, u32 lost, 1066 bool is_sack_reneg, struct rate_sample *rs); 1067 void tcp_rate_check_app_limited(struct sock *sk); 1068 1069 /* These functions determine how the current flow behaves in respect of SACK 1070 * handling. SACK is negotiated with the peer, and therefore it can vary 1071 * between different flows. 1072 * 1073 * tcp_is_sack - SACK enabled 1074 * tcp_is_reno - No SACK 1075 */ 1076 static inline int tcp_is_sack(const struct tcp_sock *tp) 1077 { 1078 return tp->rx_opt.sack_ok; 1079 } 1080 1081 static inline bool tcp_is_reno(const struct tcp_sock *tp) 1082 { 1083 return !tcp_is_sack(tp); 1084 } 1085 1086 static inline unsigned int tcp_left_out(const struct tcp_sock *tp) 1087 { 1088 return tp->sacked_out + tp->lost_out; 1089 } 1090 1091 /* This determines how many packets are "in the network" to the best 1092 * of our knowledge. In many cases it is conservative, but where 1093 * detailed information is available from the receiver (via SACK 1094 * blocks etc.) we can make more aggressive calculations. 1095 * 1096 * Use this for decisions involving congestion control, use just 1097 * tp->packets_out to determine if the send queue is empty or not. 1098 * 1099 * Read this equation as: 1100 * 1101 * "Packets sent once on transmission queue" MINUS 1102 * "Packets left network, but not honestly ACKed yet" PLUS 1103 * "Packets fast retransmitted" 1104 */ 1105 static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp) 1106 { 1107 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out; 1108 } 1109 1110 #define TCP_INFINITE_SSTHRESH 0x7fffffff 1111 1112 static inline bool tcp_in_slow_start(const struct tcp_sock *tp) 1113 { 1114 return tp->snd_cwnd < tp->snd_ssthresh; 1115 } 1116 1117 static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp) 1118 { 1119 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH; 1120 } 1121 1122 static inline bool tcp_in_cwnd_reduction(const struct sock *sk) 1123 { 1124 return (TCPF_CA_CWR | TCPF_CA_Recovery) & 1125 (1 << inet_csk(sk)->icsk_ca_state); 1126 } 1127 1128 /* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd. 1129 * The exception is cwnd reduction phase, when cwnd is decreasing towards 1130 * ssthresh. 1131 */ 1132 static inline __u32 tcp_current_ssthresh(const struct sock *sk) 1133 { 1134 const struct tcp_sock *tp = tcp_sk(sk); 1135 1136 if (tcp_in_cwnd_reduction(sk)) 1137 return tp->snd_ssthresh; 1138 else 1139 return max(tp->snd_ssthresh, 1140 ((tp->snd_cwnd >> 1) + 1141 (tp->snd_cwnd >> 2))); 1142 } 1143 1144 /* Use define here intentionally to get WARN_ON location shown at the caller */ 1145 #define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out) 1146 1147 void tcp_enter_cwr(struct sock *sk); 1148 __u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst); 1149 1150 /* The maximum number of MSS of available cwnd for which TSO defers 1151 * sending if not using sysctl_tcp_tso_win_divisor. 1152 */ 1153 static inline __u32 tcp_max_tso_deferred_mss(const struct tcp_sock *tp) 1154 { 1155 return 3; 1156 } 1157 1158 /* Returns end sequence number of the receiver's advertised window */ 1159 static inline u32 tcp_wnd_end(const struct tcp_sock *tp) 1160 { 1161 return tp->snd_una + tp->snd_wnd; 1162 } 1163 1164 /* We follow the spirit of RFC2861 to validate cwnd but implement a more 1165 * flexible approach. The RFC suggests cwnd should not be raised unless 1166 * it was fully used previously. And that's exactly what we do in 1167 * congestion avoidance mode. But in slow start we allow cwnd to grow 1168 * as long as the application has used half the cwnd. 1169 * Example : 1170 * cwnd is 10 (IW10), but application sends 9 frames. 1171 * We allow cwnd to reach 18 when all frames are ACKed. 1172 * This check is safe because it's as aggressive as slow start which already 1173 * risks 100% overshoot. The advantage is that we discourage application to 1174 * either send more filler packets or data to artificially blow up the cwnd 1175 * usage, and allow application-limited process to probe bw more aggressively. 1176 */ 1177 static inline bool tcp_is_cwnd_limited(const struct sock *sk) 1178 { 1179 const struct tcp_sock *tp = tcp_sk(sk); 1180 1181 /* If in slow start, ensure cwnd grows to twice what was ACKed. */ 1182 if (tcp_in_slow_start(tp)) 1183 return tp->snd_cwnd < 2 * tp->max_packets_out; 1184 1185 return tp->is_cwnd_limited; 1186 } 1187 1188 /* Something is really bad, we could not queue an additional packet, 1189 * because qdisc is full or receiver sent a 0 window. 1190 * We do not want to add fuel to the fire, or abort too early, 1191 * so make sure the timer we arm now is at least 200ms in the future, 1192 * regardless of current icsk_rto value (as it could be ~2ms) 1193 */ 1194 static inline unsigned long tcp_probe0_base(const struct sock *sk) 1195 { 1196 return max_t(unsigned long, inet_csk(sk)->icsk_rto, TCP_RTO_MIN); 1197 } 1198 1199 /* Variant of inet_csk_rto_backoff() used for zero window probes */ 1200 static inline unsigned long tcp_probe0_when(const struct sock *sk, 1201 unsigned long max_when) 1202 { 1203 u64 when = (u64)tcp_probe0_base(sk) << inet_csk(sk)->icsk_backoff; 1204 1205 return (unsigned long)min_t(u64, when, max_when); 1206 } 1207 1208 static inline void tcp_check_probe_timer(struct sock *sk) 1209 { 1210 if (!tcp_sk(sk)->packets_out && !inet_csk(sk)->icsk_pending) 1211 inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0, 1212 tcp_probe0_base(sk), TCP_RTO_MAX); 1213 } 1214 1215 static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq) 1216 { 1217 tp->snd_wl1 = seq; 1218 } 1219 1220 static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq) 1221 { 1222 tp->snd_wl1 = seq; 1223 } 1224 1225 /* 1226 * Calculate(/check) TCP checksum 1227 */ 1228 static inline __sum16 tcp_v4_check(int len, __be32 saddr, 1229 __be32 daddr, __wsum base) 1230 { 1231 return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base); 1232 } 1233 1234 static inline __sum16 __tcp_checksum_complete(struct sk_buff *skb) 1235 { 1236 return __skb_checksum_complete(skb); 1237 } 1238 1239 static inline bool tcp_checksum_complete(struct sk_buff *skb) 1240 { 1241 return !skb_csum_unnecessary(skb) && 1242 __tcp_checksum_complete(skb); 1243 } 1244 1245 bool tcp_add_backlog(struct sock *sk, struct sk_buff *skb); 1246 int tcp_filter(struct sock *sk, struct sk_buff *skb); 1247 1248 #undef STATE_TRACE 1249 1250 #ifdef STATE_TRACE 1251 static const char *statename[]={ 1252 "Unused","Established","Syn Sent","Syn Recv", 1253 "Fin Wait 1","Fin Wait 2","Time Wait", "Close", 1254 "Close Wait","Last ACK","Listen","Closing" 1255 }; 1256 #endif 1257 void tcp_set_state(struct sock *sk, int state); 1258 1259 void tcp_done(struct sock *sk); 1260 1261 int tcp_abort(struct sock *sk, int err); 1262 1263 static inline void tcp_sack_reset(struct tcp_options_received *rx_opt) 1264 { 1265 rx_opt->dsack = 0; 1266 rx_opt->num_sacks = 0; 1267 } 1268 1269 u32 tcp_default_init_rwnd(u32 mss); 1270 void tcp_cwnd_restart(struct sock *sk, s32 delta); 1271 1272 static inline void tcp_slow_start_after_idle_check(struct sock *sk) 1273 { 1274 const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops; 1275 struct tcp_sock *tp = tcp_sk(sk); 1276 s32 delta; 1277 1278 if (!sock_net(sk)->ipv4.sysctl_tcp_slow_start_after_idle || tp->packets_out || 1279 ca_ops->cong_control) 1280 return; 1281 delta = tcp_jiffies32 - tp->lsndtime; 1282 if (delta > inet_csk(sk)->icsk_rto) 1283 tcp_cwnd_restart(sk, delta); 1284 } 1285 1286 /* Determine a window scaling and initial window to offer. */ 1287 void tcp_select_initial_window(const struct sock *sk, int __space, 1288 __u32 mss, __u32 *rcv_wnd, 1289 __u32 *window_clamp, int wscale_ok, 1290 __u8 *rcv_wscale, __u32 init_rcv_wnd); 1291 1292 static inline int tcp_win_from_space(const struct sock *sk, int space) 1293 { 1294 int tcp_adv_win_scale = sock_net(sk)->ipv4.sysctl_tcp_adv_win_scale; 1295 1296 return tcp_adv_win_scale <= 0 ? 1297 (space>>(-tcp_adv_win_scale)) : 1298 space - (space>>tcp_adv_win_scale); 1299 } 1300 1301 /* Note: caller must be prepared to deal with negative returns */ 1302 static inline int tcp_space(const struct sock *sk) 1303 { 1304 return tcp_win_from_space(sk, sk->sk_rcvbuf - 1305 atomic_read(&sk->sk_rmem_alloc)); 1306 } 1307 1308 static inline int tcp_full_space(const struct sock *sk) 1309 { 1310 return tcp_win_from_space(sk, sk->sk_rcvbuf); 1311 } 1312 1313 extern void tcp_openreq_init_rwin(struct request_sock *req, 1314 const struct sock *sk_listener, 1315 const struct dst_entry *dst); 1316 1317 void tcp_enter_memory_pressure(struct sock *sk); 1318 void tcp_leave_memory_pressure(struct sock *sk); 1319 1320 static inline int keepalive_intvl_when(const struct tcp_sock *tp) 1321 { 1322 struct net *net = sock_net((struct sock *)tp); 1323 1324 return tp->keepalive_intvl ? : net->ipv4.sysctl_tcp_keepalive_intvl; 1325 } 1326 1327 static inline int keepalive_time_when(const struct tcp_sock *tp) 1328 { 1329 struct net *net = sock_net((struct sock *)tp); 1330 1331 return tp->keepalive_time ? : net->ipv4.sysctl_tcp_keepalive_time; 1332 } 1333 1334 static inline int keepalive_probes(const struct tcp_sock *tp) 1335 { 1336 struct net *net = sock_net((struct sock *)tp); 1337 1338 return tp->keepalive_probes ? : net->ipv4.sysctl_tcp_keepalive_probes; 1339 } 1340 1341 static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp) 1342 { 1343 const struct inet_connection_sock *icsk = &tp->inet_conn; 1344 1345 return min_t(u32, tcp_jiffies32 - icsk->icsk_ack.lrcvtime, 1346 tcp_jiffies32 - tp->rcv_tstamp); 1347 } 1348 1349 static inline int tcp_fin_time(const struct sock *sk) 1350 { 1351 int fin_timeout = tcp_sk(sk)->linger2 ? : sock_net(sk)->ipv4.sysctl_tcp_fin_timeout; 1352 const int rto = inet_csk(sk)->icsk_rto; 1353 1354 if (fin_timeout < (rto << 2) - (rto >> 1)) 1355 fin_timeout = (rto << 2) - (rto >> 1); 1356 1357 return fin_timeout; 1358 } 1359 1360 static inline bool tcp_paws_check(const struct tcp_options_received *rx_opt, 1361 int paws_win) 1362 { 1363 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win) 1364 return true; 1365 if (unlikely(get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS)) 1366 return true; 1367 /* 1368 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0, 1369 * then following tcp messages have valid values. Ignore 0 value, 1370 * or else 'negative' tsval might forbid us to accept their packets. 1371 */ 1372 if (!rx_opt->ts_recent) 1373 return true; 1374 return false; 1375 } 1376 1377 static inline bool tcp_paws_reject(const struct tcp_options_received *rx_opt, 1378 int rst) 1379 { 1380 if (tcp_paws_check(rx_opt, 0)) 1381 return false; 1382 1383 /* RST segments are not recommended to carry timestamp, 1384 and, if they do, it is recommended to ignore PAWS because 1385 "their cleanup function should take precedence over timestamps." 1386 Certainly, it is mistake. It is necessary to understand the reasons 1387 of this constraint to relax it: if peer reboots, clock may go 1388 out-of-sync and half-open connections will not be reset. 1389 Actually, the problem would be not existing if all 1390 the implementations followed draft about maintaining clock 1391 via reboots. Linux-2.2 DOES NOT! 1392 1393 However, we can relax time bounds for RST segments to MSL. 1394 */ 1395 if (rst && get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_MSL) 1396 return false; 1397 return true; 1398 } 1399 1400 bool tcp_oow_rate_limited(struct net *net, const struct sk_buff *skb, 1401 int mib_idx, u32 *last_oow_ack_time); 1402 1403 static inline void tcp_mib_init(struct net *net) 1404 { 1405 /* See RFC 2012 */ 1406 TCP_ADD_STATS(net, TCP_MIB_RTOALGORITHM, 1); 1407 TCP_ADD_STATS(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ); 1408 TCP_ADD_STATS(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ); 1409 TCP_ADD_STATS(net, TCP_MIB_MAXCONN, -1); 1410 } 1411 1412 /* from STCP */ 1413 static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp) 1414 { 1415 tp->lost_skb_hint = NULL; 1416 } 1417 1418 static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp) 1419 { 1420 tcp_clear_retrans_hints_partial(tp); 1421 tp->retransmit_skb_hint = NULL; 1422 } 1423 1424 union tcp_md5_addr { 1425 struct in_addr a4; 1426 #if IS_ENABLED(CONFIG_IPV6) 1427 struct in6_addr a6; 1428 #endif 1429 }; 1430 1431 /* - key database */ 1432 struct tcp_md5sig_key { 1433 struct hlist_node node; 1434 u8 keylen; 1435 u8 family; /* AF_INET or AF_INET6 */ 1436 union tcp_md5_addr addr; 1437 u8 prefixlen; 1438 u8 key[TCP_MD5SIG_MAXKEYLEN]; 1439 struct rcu_head rcu; 1440 }; 1441 1442 /* - sock block */ 1443 struct tcp_md5sig_info { 1444 struct hlist_head head; 1445 struct rcu_head rcu; 1446 }; 1447 1448 /* - pseudo header */ 1449 struct tcp4_pseudohdr { 1450 __be32 saddr; 1451 __be32 daddr; 1452 __u8 pad; 1453 __u8 protocol; 1454 __be16 len; 1455 }; 1456 1457 struct tcp6_pseudohdr { 1458 struct in6_addr saddr; 1459 struct in6_addr daddr; 1460 __be32 len; 1461 __be32 protocol; /* including padding */ 1462 }; 1463 1464 union tcp_md5sum_block { 1465 struct tcp4_pseudohdr ip4; 1466 #if IS_ENABLED(CONFIG_IPV6) 1467 struct tcp6_pseudohdr ip6; 1468 #endif 1469 }; 1470 1471 /* - pool: digest algorithm, hash description and scratch buffer */ 1472 struct tcp_md5sig_pool { 1473 struct ahash_request *md5_req; 1474 void *scratch; 1475 }; 1476 1477 /* - functions */ 1478 int tcp_v4_md5_hash_skb(char *md5_hash, const struct tcp_md5sig_key *key, 1479 const struct sock *sk, const struct sk_buff *skb); 1480 int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr, 1481 int family, u8 prefixlen, const u8 *newkey, u8 newkeylen, 1482 gfp_t gfp); 1483 int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr, 1484 int family, u8 prefixlen); 1485 struct tcp_md5sig_key *tcp_v4_md5_lookup(const struct sock *sk, 1486 const struct sock *addr_sk); 1487 1488 #ifdef CONFIG_TCP_MD5SIG 1489 struct tcp_md5sig_key *tcp_md5_do_lookup(const struct sock *sk, 1490 const union tcp_md5_addr *addr, 1491 int family); 1492 #define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key) 1493 #else 1494 static inline struct tcp_md5sig_key *tcp_md5_do_lookup(const struct sock *sk, 1495 const union tcp_md5_addr *addr, 1496 int family) 1497 { 1498 return NULL; 1499 } 1500 #define tcp_twsk_md5_key(twsk) NULL 1501 #endif 1502 1503 bool tcp_alloc_md5sig_pool(void); 1504 1505 struct tcp_md5sig_pool *tcp_get_md5sig_pool(void); 1506 static inline void tcp_put_md5sig_pool(void) 1507 { 1508 local_bh_enable(); 1509 } 1510 1511 int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *, 1512 unsigned int header_len); 1513 int tcp_md5_hash_key(struct tcp_md5sig_pool *hp, 1514 const struct tcp_md5sig_key *key); 1515 1516 /* From tcp_fastopen.c */ 1517 void tcp_fastopen_cache_get(struct sock *sk, u16 *mss, 1518 struct tcp_fastopen_cookie *cookie); 1519 void tcp_fastopen_cache_set(struct sock *sk, u16 mss, 1520 struct tcp_fastopen_cookie *cookie, bool syn_lost, 1521 u16 try_exp); 1522 struct tcp_fastopen_request { 1523 /* Fast Open cookie. Size 0 means a cookie request */ 1524 struct tcp_fastopen_cookie cookie; 1525 struct msghdr *data; /* data in MSG_FASTOPEN */ 1526 size_t size; 1527 int copied; /* queued in tcp_connect() */ 1528 }; 1529 void tcp_free_fastopen_req(struct tcp_sock *tp); 1530 void tcp_fastopen_destroy_cipher(struct sock *sk); 1531 void tcp_fastopen_ctx_destroy(struct net *net); 1532 int tcp_fastopen_reset_cipher(struct net *net, struct sock *sk, 1533 void *key, unsigned int len); 1534 void tcp_fastopen_add_skb(struct sock *sk, struct sk_buff *skb); 1535 struct sock *tcp_try_fastopen(struct sock *sk, struct sk_buff *skb, 1536 struct request_sock *req, 1537 struct tcp_fastopen_cookie *foc, 1538 const struct dst_entry *dst); 1539 void tcp_fastopen_init_key_once(struct net *net); 1540 bool tcp_fastopen_cookie_check(struct sock *sk, u16 *mss, 1541 struct tcp_fastopen_cookie *cookie); 1542 bool tcp_fastopen_defer_connect(struct sock *sk, int *err); 1543 #define TCP_FASTOPEN_KEY_LENGTH 16 1544 1545 /* Fastopen key context */ 1546 struct tcp_fastopen_context { 1547 struct crypto_cipher *tfm; 1548 __u8 key[TCP_FASTOPEN_KEY_LENGTH]; 1549 struct rcu_head rcu; 1550 }; 1551 1552 extern unsigned int sysctl_tcp_fastopen_blackhole_timeout; 1553 void tcp_fastopen_active_disable(struct sock *sk); 1554 bool tcp_fastopen_active_should_disable(struct sock *sk); 1555 void tcp_fastopen_active_disable_ofo_check(struct sock *sk); 1556 void tcp_fastopen_active_detect_blackhole(struct sock *sk, bool expired); 1557 1558 /* Latencies incurred by various limits for a sender. They are 1559 * chronograph-like stats that are mutually exclusive. 1560 */ 1561 enum tcp_chrono { 1562 TCP_CHRONO_UNSPEC, 1563 TCP_CHRONO_BUSY, /* Actively sending data (non-empty write queue) */ 1564 TCP_CHRONO_RWND_LIMITED, /* Stalled by insufficient receive window */ 1565 TCP_CHRONO_SNDBUF_LIMITED, /* Stalled by insufficient send buffer */ 1566 __TCP_CHRONO_MAX, 1567 }; 1568 1569 void tcp_chrono_start(struct sock *sk, const enum tcp_chrono type); 1570 void tcp_chrono_stop(struct sock *sk, const enum tcp_chrono type); 1571 1572 /* This helper is needed, because skb->tcp_tsorted_anchor uses 1573 * the same memory storage than skb->destructor/_skb_refdst 1574 */ 1575 static inline void tcp_skb_tsorted_anchor_cleanup(struct sk_buff *skb) 1576 { 1577 skb->destructor = NULL; 1578 skb->_skb_refdst = 0UL; 1579 } 1580 1581 #define tcp_skb_tsorted_save(skb) { \ 1582 unsigned long _save = skb->_skb_refdst; \ 1583 skb->_skb_refdst = 0UL; 1584 1585 #define tcp_skb_tsorted_restore(skb) \ 1586 skb->_skb_refdst = _save; \ 1587 } 1588 1589 void tcp_write_queue_purge(struct sock *sk); 1590 1591 static inline struct sk_buff *tcp_rtx_queue_head(const struct sock *sk) 1592 { 1593 return skb_rb_first(&sk->tcp_rtx_queue); 1594 } 1595 1596 static inline struct sk_buff *tcp_write_queue_head(const struct sock *sk) 1597 { 1598 return skb_peek(&sk->sk_write_queue); 1599 } 1600 1601 static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk) 1602 { 1603 return skb_peek_tail(&sk->sk_write_queue); 1604 } 1605 1606 #define tcp_for_write_queue_from_safe(skb, tmp, sk) \ 1607 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp) 1608 1609 static inline struct sk_buff *tcp_send_head(const struct sock *sk) 1610 { 1611 return skb_peek(&sk->sk_write_queue); 1612 } 1613 1614 static inline bool tcp_skb_is_last(const struct sock *sk, 1615 const struct sk_buff *skb) 1616 { 1617 return skb_queue_is_last(&sk->sk_write_queue, skb); 1618 } 1619 1620 static inline bool tcp_write_queue_empty(const struct sock *sk) 1621 { 1622 return skb_queue_empty(&sk->sk_write_queue); 1623 } 1624 1625 static inline bool tcp_rtx_queue_empty(const struct sock *sk) 1626 { 1627 return RB_EMPTY_ROOT(&sk->tcp_rtx_queue); 1628 } 1629 1630 static inline bool tcp_rtx_and_write_queues_empty(const struct sock *sk) 1631 { 1632 return tcp_rtx_queue_empty(sk) && tcp_write_queue_empty(sk); 1633 } 1634 1635 static inline void tcp_check_send_head(struct sock *sk, struct sk_buff *skb_unlinked) 1636 { 1637 if (tcp_write_queue_empty(sk)) 1638 tcp_chrono_stop(sk, TCP_CHRONO_BUSY); 1639 } 1640 1641 static inline void __tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb) 1642 { 1643 __skb_queue_tail(&sk->sk_write_queue, skb); 1644 } 1645 1646 static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb) 1647 { 1648 __tcp_add_write_queue_tail(sk, skb); 1649 1650 /* Queue it, remembering where we must start sending. */ 1651 if (sk->sk_write_queue.next == skb) 1652 tcp_chrono_start(sk, TCP_CHRONO_BUSY); 1653 } 1654 1655 /* Insert new before skb on the write queue of sk. */ 1656 static inline void tcp_insert_write_queue_before(struct sk_buff *new, 1657 struct sk_buff *skb, 1658 struct sock *sk) 1659 { 1660 __skb_queue_before(&sk->sk_write_queue, skb, new); 1661 } 1662 1663 static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk) 1664 { 1665 tcp_skb_tsorted_anchor_cleanup(skb); 1666 __skb_unlink(skb, &sk->sk_write_queue); 1667 } 1668 1669 void tcp_rbtree_insert(struct rb_root *root, struct sk_buff *skb); 1670 1671 static inline void tcp_rtx_queue_unlink(struct sk_buff *skb, struct sock *sk) 1672 { 1673 tcp_skb_tsorted_anchor_cleanup(skb); 1674 rb_erase(&skb->rbnode, &sk->tcp_rtx_queue); 1675 } 1676 1677 static inline void tcp_rtx_queue_unlink_and_free(struct sk_buff *skb, struct sock *sk) 1678 { 1679 list_del(&skb->tcp_tsorted_anchor); 1680 tcp_rtx_queue_unlink(skb, sk); 1681 sk_wmem_free_skb(sk, skb); 1682 } 1683 1684 static inline void tcp_push_pending_frames(struct sock *sk) 1685 { 1686 if (tcp_send_head(sk)) { 1687 struct tcp_sock *tp = tcp_sk(sk); 1688 1689 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle); 1690 } 1691 } 1692 1693 /* Start sequence of the skb just after the highest skb with SACKed 1694 * bit, valid only if sacked_out > 0 or when the caller has ensured 1695 * validity by itself. 1696 */ 1697 static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp) 1698 { 1699 if (!tp->sacked_out) 1700 return tp->snd_una; 1701 1702 if (tp->highest_sack == NULL) 1703 return tp->snd_nxt; 1704 1705 return TCP_SKB_CB(tp->highest_sack)->seq; 1706 } 1707 1708 static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb) 1709 { 1710 tcp_sk(sk)->highest_sack = skb_rb_next(skb); 1711 } 1712 1713 static inline struct sk_buff *tcp_highest_sack(struct sock *sk) 1714 { 1715 return tcp_sk(sk)->highest_sack; 1716 } 1717 1718 static inline void tcp_highest_sack_reset(struct sock *sk) 1719 { 1720 tcp_sk(sk)->highest_sack = tcp_rtx_queue_head(sk); 1721 } 1722 1723 /* Called when old skb is about to be deleted and replaced by new skb */ 1724 static inline void tcp_highest_sack_replace(struct sock *sk, 1725 struct sk_buff *old, 1726 struct sk_buff *new) 1727 { 1728 if (old == tcp_highest_sack(sk)) 1729 tcp_sk(sk)->highest_sack = new; 1730 } 1731 1732 /* This helper checks if socket has IP_TRANSPARENT set */ 1733 static inline bool inet_sk_transparent(const struct sock *sk) 1734 { 1735 switch (sk->sk_state) { 1736 case TCP_TIME_WAIT: 1737 return inet_twsk(sk)->tw_transparent; 1738 case TCP_NEW_SYN_RECV: 1739 return inet_rsk(inet_reqsk(sk))->no_srccheck; 1740 } 1741 return inet_sk(sk)->transparent; 1742 } 1743 1744 /* Determines whether this is a thin stream (which may suffer from 1745 * increased latency). Used to trigger latency-reducing mechanisms. 1746 */ 1747 static inline bool tcp_stream_is_thin(struct tcp_sock *tp) 1748 { 1749 return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp); 1750 } 1751 1752 /* /proc */ 1753 enum tcp_seq_states { 1754 TCP_SEQ_STATE_LISTENING, 1755 TCP_SEQ_STATE_ESTABLISHED, 1756 }; 1757 1758 void *tcp_seq_start(struct seq_file *seq, loff_t *pos); 1759 void *tcp_seq_next(struct seq_file *seq, void *v, loff_t *pos); 1760 void tcp_seq_stop(struct seq_file *seq, void *v); 1761 1762 struct tcp_seq_afinfo { 1763 sa_family_t family; 1764 }; 1765 1766 struct tcp_iter_state { 1767 struct seq_net_private p; 1768 enum tcp_seq_states state; 1769 struct sock *syn_wait_sk; 1770 int bucket, offset, sbucket, num; 1771 loff_t last_pos; 1772 }; 1773 1774 extern struct request_sock_ops tcp_request_sock_ops; 1775 extern struct request_sock_ops tcp6_request_sock_ops; 1776 1777 void tcp_v4_destroy_sock(struct sock *sk); 1778 1779 struct sk_buff *tcp_gso_segment(struct sk_buff *skb, 1780 netdev_features_t features); 1781 struct sk_buff **tcp_gro_receive(struct sk_buff **head, struct sk_buff *skb); 1782 int tcp_gro_complete(struct sk_buff *skb); 1783 1784 void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr, __be32 daddr); 1785 1786 static inline u32 tcp_notsent_lowat(const struct tcp_sock *tp) 1787 { 1788 struct net *net = sock_net((struct sock *)tp); 1789 return tp->notsent_lowat ?: net->ipv4.sysctl_tcp_notsent_lowat; 1790 } 1791 1792 static inline bool tcp_stream_memory_free(const struct sock *sk) 1793 { 1794 const struct tcp_sock *tp = tcp_sk(sk); 1795 u32 notsent_bytes = tp->write_seq - tp->snd_nxt; 1796 1797 return notsent_bytes < tcp_notsent_lowat(tp); 1798 } 1799 1800 #ifdef CONFIG_PROC_FS 1801 int tcp4_proc_init(void); 1802 void tcp4_proc_exit(void); 1803 #endif 1804 1805 int tcp_rtx_synack(const struct sock *sk, struct request_sock *req); 1806 int tcp_conn_request(struct request_sock_ops *rsk_ops, 1807 const struct tcp_request_sock_ops *af_ops, 1808 struct sock *sk, struct sk_buff *skb); 1809 1810 /* TCP af-specific functions */ 1811 struct tcp_sock_af_ops { 1812 #ifdef CONFIG_TCP_MD5SIG 1813 struct tcp_md5sig_key *(*md5_lookup) (const struct sock *sk, 1814 const struct sock *addr_sk); 1815 int (*calc_md5_hash)(char *location, 1816 const struct tcp_md5sig_key *md5, 1817 const struct sock *sk, 1818 const struct sk_buff *skb); 1819 int (*md5_parse)(struct sock *sk, 1820 int optname, 1821 char __user *optval, 1822 int optlen); 1823 #endif 1824 }; 1825 1826 struct tcp_request_sock_ops { 1827 u16 mss_clamp; 1828 #ifdef CONFIG_TCP_MD5SIG 1829 struct tcp_md5sig_key *(*req_md5_lookup)(const struct sock *sk, 1830 const struct sock *addr_sk); 1831 int (*calc_md5_hash) (char *location, 1832 const struct tcp_md5sig_key *md5, 1833 const struct sock *sk, 1834 const struct sk_buff *skb); 1835 #endif 1836 void (*init_req)(struct request_sock *req, 1837 const struct sock *sk_listener, 1838 struct sk_buff *skb); 1839 #ifdef CONFIG_SYN_COOKIES 1840 __u32 (*cookie_init_seq)(const struct sk_buff *skb, 1841 __u16 *mss); 1842 #endif 1843 struct dst_entry *(*route_req)(const struct sock *sk, struct flowi *fl, 1844 const struct request_sock *req); 1845 u32 (*init_seq)(const struct sk_buff *skb); 1846 u32 (*init_ts_off)(const struct net *net, const struct sk_buff *skb); 1847 int (*send_synack)(const struct sock *sk, struct dst_entry *dst, 1848 struct flowi *fl, struct request_sock *req, 1849 struct tcp_fastopen_cookie *foc, 1850 enum tcp_synack_type synack_type); 1851 }; 1852 1853 #ifdef CONFIG_SYN_COOKIES 1854 static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops, 1855 const struct sock *sk, struct sk_buff *skb, 1856 __u16 *mss) 1857 { 1858 tcp_synq_overflow(sk); 1859 __NET_INC_STATS(sock_net(sk), LINUX_MIB_SYNCOOKIESSENT); 1860 return ops->cookie_init_seq(skb, mss); 1861 } 1862 #else 1863 static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops, 1864 const struct sock *sk, struct sk_buff *skb, 1865 __u16 *mss) 1866 { 1867 return 0; 1868 } 1869 #endif 1870 1871 int tcpv4_offload_init(void); 1872 1873 void tcp_v4_init(void); 1874 void tcp_init(void); 1875 1876 /* tcp_recovery.c */ 1877 void tcp_mark_skb_lost(struct sock *sk, struct sk_buff *skb); 1878 void tcp_newreno_mark_lost(struct sock *sk, bool snd_una_advanced); 1879 extern s32 tcp_rack_skb_timeout(struct tcp_sock *tp, struct sk_buff *skb, 1880 u32 reo_wnd); 1881 extern void tcp_rack_mark_lost(struct sock *sk); 1882 extern void tcp_rack_advance(struct tcp_sock *tp, u8 sacked, u32 end_seq, 1883 u64 xmit_time); 1884 extern void tcp_rack_reo_timeout(struct sock *sk); 1885 extern void tcp_rack_update_reo_wnd(struct sock *sk, struct rate_sample *rs); 1886 1887 /* At how many usecs into the future should the RTO fire? */ 1888 static inline s64 tcp_rto_delta_us(const struct sock *sk) 1889 { 1890 const struct sk_buff *skb = tcp_rtx_queue_head(sk); 1891 u32 rto = inet_csk(sk)->icsk_rto; 1892 u64 rto_time_stamp_us = skb->skb_mstamp + jiffies_to_usecs(rto); 1893 1894 return rto_time_stamp_us - tcp_sk(sk)->tcp_mstamp; 1895 } 1896 1897 /* 1898 * Save and compile IPv4 options, return a pointer to it 1899 */ 1900 static inline struct ip_options_rcu *tcp_v4_save_options(struct net *net, 1901 struct sk_buff *skb) 1902 { 1903 const struct ip_options *opt = &TCP_SKB_CB(skb)->header.h4.opt; 1904 struct ip_options_rcu *dopt = NULL; 1905 1906 if (opt->optlen) { 1907 int opt_size = sizeof(*dopt) + opt->optlen; 1908 1909 dopt = kmalloc(opt_size, GFP_ATOMIC); 1910 if (dopt && __ip_options_echo(net, &dopt->opt, skb, opt)) { 1911 kfree(dopt); 1912 dopt = NULL; 1913 } 1914 } 1915 return dopt; 1916 } 1917 1918 /* locally generated TCP pure ACKs have skb->truesize == 2 1919 * (check tcp_send_ack() in net/ipv4/tcp_output.c ) 1920 * This is much faster than dissecting the packet to find out. 1921 * (Think of GRE encapsulations, IPv4, IPv6, ...) 1922 */ 1923 static inline bool skb_is_tcp_pure_ack(const struct sk_buff *skb) 1924 { 1925 return skb->truesize == 2; 1926 } 1927 1928 static inline void skb_set_tcp_pure_ack(struct sk_buff *skb) 1929 { 1930 skb->truesize = 2; 1931 } 1932 1933 static inline int tcp_inq(struct sock *sk) 1934 { 1935 struct tcp_sock *tp = tcp_sk(sk); 1936 int answ; 1937 1938 if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) { 1939 answ = 0; 1940 } else if (sock_flag(sk, SOCK_URGINLINE) || 1941 !tp->urg_data || 1942 before(tp->urg_seq, tp->copied_seq) || 1943 !before(tp->urg_seq, tp->rcv_nxt)) { 1944 1945 answ = tp->rcv_nxt - tp->copied_seq; 1946 1947 /* Subtract 1, if FIN was received */ 1948 if (answ && sock_flag(sk, SOCK_DONE)) 1949 answ--; 1950 } else { 1951 answ = tp->urg_seq - tp->copied_seq; 1952 } 1953 1954 return answ; 1955 } 1956 1957 int tcp_peek_len(struct socket *sock); 1958 1959 static inline void tcp_segs_in(struct tcp_sock *tp, const struct sk_buff *skb) 1960 { 1961 u16 segs_in; 1962 1963 segs_in = max_t(u16, 1, skb_shinfo(skb)->gso_segs); 1964 tp->segs_in += segs_in; 1965 if (skb->len > tcp_hdrlen(skb)) 1966 tp->data_segs_in += segs_in; 1967 } 1968 1969 /* 1970 * TCP listen path runs lockless. 1971 * We forced "struct sock" to be const qualified to make sure 1972 * we don't modify one of its field by mistake. 1973 * Here, we increment sk_drops which is an atomic_t, so we can safely 1974 * make sock writable again. 1975 */ 1976 static inline void tcp_listendrop(const struct sock *sk) 1977 { 1978 atomic_inc(&((struct sock *)sk)->sk_drops); 1979 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS); 1980 } 1981 1982 enum hrtimer_restart tcp_pace_kick(struct hrtimer *timer); 1983 1984 /* 1985 * Interface for adding Upper Level Protocols over TCP 1986 */ 1987 1988 #define TCP_ULP_NAME_MAX 16 1989 #define TCP_ULP_MAX 128 1990 #define TCP_ULP_BUF_MAX (TCP_ULP_NAME_MAX*TCP_ULP_MAX) 1991 1992 enum { 1993 TCP_ULP_TLS, 1994 TCP_ULP_BPF, 1995 }; 1996 1997 struct tcp_ulp_ops { 1998 struct list_head list; 1999 2000 /* initialize ulp */ 2001 int (*init)(struct sock *sk); 2002 /* cleanup ulp */ 2003 void (*release)(struct sock *sk); 2004 2005 int uid; 2006 char name[TCP_ULP_NAME_MAX]; 2007 bool user_visible; 2008 struct module *owner; 2009 }; 2010 int tcp_register_ulp(struct tcp_ulp_ops *type); 2011 void tcp_unregister_ulp(struct tcp_ulp_ops *type); 2012 int tcp_set_ulp(struct sock *sk, const char *name); 2013 int tcp_set_ulp_id(struct sock *sk, const int ulp); 2014 void tcp_get_available_ulp(char *buf, size_t len); 2015 void tcp_cleanup_ulp(struct sock *sk); 2016 2017 /* Call BPF_SOCK_OPS program that returns an int. If the return value 2018 * is < 0, then the BPF op failed (for example if the loaded BPF 2019 * program does not support the chosen operation or there is no BPF 2020 * program loaded). 2021 */ 2022 #ifdef CONFIG_BPF 2023 static inline int tcp_call_bpf(struct sock *sk, int op, u32 nargs, u32 *args) 2024 { 2025 struct bpf_sock_ops_kern sock_ops; 2026 int ret; 2027 2028 memset(&sock_ops, 0, offsetof(struct bpf_sock_ops_kern, temp)); 2029 if (sk_fullsock(sk)) { 2030 sock_ops.is_fullsock = 1; 2031 sock_owned_by_me(sk); 2032 } 2033 2034 sock_ops.sk = sk; 2035 sock_ops.op = op; 2036 if (nargs > 0) 2037 memcpy(sock_ops.args, args, nargs * sizeof(*args)); 2038 2039 ret = BPF_CGROUP_RUN_PROG_SOCK_OPS(&sock_ops); 2040 if (ret == 0) 2041 ret = sock_ops.reply; 2042 else 2043 ret = -1; 2044 return ret; 2045 } 2046 2047 static inline int tcp_call_bpf_2arg(struct sock *sk, int op, u32 arg1, u32 arg2) 2048 { 2049 u32 args[2] = {arg1, arg2}; 2050 2051 return tcp_call_bpf(sk, op, 2, args); 2052 } 2053 2054 static inline int tcp_call_bpf_3arg(struct sock *sk, int op, u32 arg1, u32 arg2, 2055 u32 arg3) 2056 { 2057 u32 args[3] = {arg1, arg2, arg3}; 2058 2059 return tcp_call_bpf(sk, op, 3, args); 2060 } 2061 2062 #else 2063 static inline int tcp_call_bpf(struct sock *sk, int op, u32 nargs, u32 *args) 2064 { 2065 return -EPERM; 2066 } 2067 2068 static inline int tcp_call_bpf_2arg(struct sock *sk, int op, u32 arg1, u32 arg2) 2069 { 2070 return -EPERM; 2071 } 2072 2073 static inline int tcp_call_bpf_3arg(struct sock *sk, int op, u32 arg1, u32 arg2, 2074 u32 arg3) 2075 { 2076 return -EPERM; 2077 } 2078 2079 #endif 2080 2081 static inline u32 tcp_timeout_init(struct sock *sk) 2082 { 2083 int timeout; 2084 2085 timeout = tcp_call_bpf(sk, BPF_SOCK_OPS_TIMEOUT_INIT, 0, NULL); 2086 2087 if (timeout <= 0) 2088 timeout = TCP_TIMEOUT_INIT; 2089 return timeout; 2090 } 2091 2092 static inline u32 tcp_rwnd_init_bpf(struct sock *sk) 2093 { 2094 int rwnd; 2095 2096 rwnd = tcp_call_bpf(sk, BPF_SOCK_OPS_RWND_INIT, 0, NULL); 2097 2098 if (rwnd < 0) 2099 rwnd = 0; 2100 return rwnd; 2101 } 2102 2103 static inline bool tcp_bpf_ca_needs_ecn(struct sock *sk) 2104 { 2105 return (tcp_call_bpf(sk, BPF_SOCK_OPS_NEEDS_ECN, 0, NULL) == 1); 2106 } 2107 2108 #if IS_ENABLED(CONFIG_SMC) 2109 extern struct static_key_false tcp_have_smc; 2110 #endif 2111 2112 #if IS_ENABLED(CONFIG_TLS_DEVICE) 2113 void clean_acked_data_enable(struct inet_connection_sock *icsk, 2114 void (*cad)(struct sock *sk, u32 ack_seq)); 2115 void clean_acked_data_disable(struct inet_connection_sock *icsk); 2116 2117 #endif 2118 2119 #endif /* _TCP_H */ 2120