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 49 #include <linux/bpf.h> 50 #include <linux/filter.h> 51 #include <linux/bpf-cgroup.h> 52 53 extern struct inet_hashinfo tcp_hashinfo; 54 55 extern struct percpu_counter tcp_orphan_count; 56 void tcp_time_wait(struct sock *sk, int state, int timeo); 57 58 #define MAX_TCP_HEADER (128 + MAX_HEADER) 59 #define MAX_TCP_OPTION_SPACE 40 60 61 /* 62 * Never offer a window over 32767 without using window scaling. Some 63 * poor stacks do signed 16bit maths! 64 */ 65 #define MAX_TCP_WINDOW 32767U 66 67 /* Minimal accepted MSS. It is (60+60+8) - (20+20). */ 68 #define TCP_MIN_MSS 88U 69 70 /* The least MTU to use for probing */ 71 #define TCP_BASE_MSS 1024 72 73 /* probing interval, default to 10 minutes as per RFC4821 */ 74 #define TCP_PROBE_INTERVAL 600 75 76 /* Specify interval when tcp mtu probing will stop */ 77 #define TCP_PROBE_THRESHOLD 8 78 79 /* After receiving this amount of duplicate ACKs fast retransmit starts. */ 80 #define TCP_FASTRETRANS_THRESH 3 81 82 /* Maximal number of ACKs sent quickly to accelerate slow-start. */ 83 #define TCP_MAX_QUICKACKS 16U 84 85 /* Maximal number of window scale according to RFC1323 */ 86 #define TCP_MAX_WSCALE 14U 87 88 /* urg_data states */ 89 #define TCP_URG_VALID 0x0100 90 #define TCP_URG_NOTYET 0x0200 91 #define TCP_URG_READ 0x0400 92 93 #define TCP_RETR1 3 /* 94 * This is how many retries it does before it 95 * tries to figure out if the gateway is 96 * down. Minimal RFC value is 3; it corresponds 97 * to ~3sec-8min depending on RTO. 98 */ 99 100 #define TCP_RETR2 15 /* 101 * This should take at least 102 * 90 minutes to time out. 103 * RFC1122 says that the limit is 100 sec. 104 * 15 is ~13-30min depending on RTO. 105 */ 106 107 #define TCP_SYN_RETRIES 6 /* This is how many retries are done 108 * when active opening a connection. 109 * RFC1122 says the minimum retry MUST 110 * be at least 180secs. Nevertheless 111 * this value is corresponding to 112 * 63secs of retransmission with the 113 * current initial RTO. 114 */ 115 116 #define TCP_SYNACK_RETRIES 5 /* This is how may retries are done 117 * when passive opening a connection. 118 * This is corresponding to 31secs of 119 * retransmission with the current 120 * initial RTO. 121 */ 122 123 #define TCP_TIMEWAIT_LEN (60*HZ) /* how long to wait to destroy TIME-WAIT 124 * state, about 60 seconds */ 125 #define TCP_FIN_TIMEOUT TCP_TIMEWAIT_LEN 126 /* BSD style FIN_WAIT2 deadlock breaker. 127 * It used to be 3min, new value is 60sec, 128 * to combine FIN-WAIT-2 timeout with 129 * TIME-WAIT timer. 130 */ 131 132 #define TCP_DELACK_MAX ((unsigned)(HZ/5)) /* maximal time to delay before sending an ACK */ 133 #if HZ >= 100 134 #define TCP_DELACK_MIN ((unsigned)(HZ/25)) /* minimal time to delay before sending an ACK */ 135 #define TCP_ATO_MIN ((unsigned)(HZ/25)) 136 #else 137 #define TCP_DELACK_MIN 4U 138 #define TCP_ATO_MIN 4U 139 #endif 140 #define TCP_RTO_MAX ((unsigned)(120*HZ)) 141 #define TCP_RTO_MIN ((unsigned)(HZ/5)) 142 #define TCP_TIMEOUT_MIN (2U) /* Min timeout for TCP timers in jiffies */ 143 #define TCP_TIMEOUT_INIT ((unsigned)(1*HZ)) /* RFC6298 2.1 initial RTO value */ 144 #define TCP_TIMEOUT_FALLBACK ((unsigned)(3*HZ)) /* RFC 1122 initial RTO value, now 145 * used as a fallback RTO for the 146 * initial data transmission if no 147 * valid RTT sample has been acquired, 148 * most likely due to retrans in 3WHS. 149 */ 150 151 #define TCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ/2U)) /* Maximal interval between probes 152 * for local resources. 153 */ 154 #define TCP_KEEPALIVE_TIME (120*60*HZ) /* two hours */ 155 #define TCP_KEEPALIVE_PROBES 9 /* Max of 9 keepalive probes */ 156 #define TCP_KEEPALIVE_INTVL (75*HZ) 157 158 #define MAX_TCP_KEEPIDLE 32767 159 #define MAX_TCP_KEEPINTVL 32767 160 #define MAX_TCP_KEEPCNT 127 161 #define MAX_TCP_SYNCNT 127 162 163 #define TCP_SYNQ_INTERVAL (HZ/5) /* Period of SYNACK timer */ 164 165 #define TCP_PAWS_24DAYS (60 * 60 * 24 * 24) 166 #define TCP_PAWS_MSL 60 /* Per-host timestamps are invalidated 167 * after this time. It should be equal 168 * (or greater than) TCP_TIMEWAIT_LEN 169 * to provide reliability equal to one 170 * provided by timewait state. 171 */ 172 #define TCP_PAWS_WINDOW 1 /* Replay window for per-host 173 * timestamps. It must be less than 174 * minimal timewait lifetime. 175 */ 176 /* 177 * TCP option 178 */ 179 180 #define TCPOPT_NOP 1 /* Padding */ 181 #define TCPOPT_EOL 0 /* End of options */ 182 #define TCPOPT_MSS 2 /* Segment size negotiating */ 183 #define TCPOPT_WINDOW 3 /* Window scaling */ 184 #define TCPOPT_SACK_PERM 4 /* SACK Permitted */ 185 #define TCPOPT_SACK 5 /* SACK Block */ 186 #define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */ 187 #define TCPOPT_MD5SIG 19 /* MD5 Signature (RFC2385) */ 188 #define TCPOPT_FASTOPEN 34 /* Fast open (RFC7413) */ 189 #define TCPOPT_EXP 254 /* Experimental */ 190 /* Magic number to be after the option value for sharing TCP 191 * experimental options. See draft-ietf-tcpm-experimental-options-00.txt 192 */ 193 #define TCPOPT_FASTOPEN_MAGIC 0xF989 194 195 /* 196 * TCP option lengths 197 */ 198 199 #define TCPOLEN_MSS 4 200 #define TCPOLEN_WINDOW 3 201 #define TCPOLEN_SACK_PERM 2 202 #define TCPOLEN_TIMESTAMP 10 203 #define TCPOLEN_MD5SIG 18 204 #define TCPOLEN_FASTOPEN_BASE 2 205 #define TCPOLEN_EXP_FASTOPEN_BASE 4 206 207 /* But this is what stacks really send out. */ 208 #define TCPOLEN_TSTAMP_ALIGNED 12 209 #define TCPOLEN_WSCALE_ALIGNED 4 210 #define TCPOLEN_SACKPERM_ALIGNED 4 211 #define TCPOLEN_SACK_BASE 2 212 #define TCPOLEN_SACK_BASE_ALIGNED 4 213 #define TCPOLEN_SACK_PERBLOCK 8 214 #define TCPOLEN_MD5SIG_ALIGNED 20 215 #define TCPOLEN_MSS_ALIGNED 4 216 217 /* 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_fastopen; 244 extern int sysctl_tcp_retrans_collapse; 245 extern int sysctl_tcp_stdurg; 246 extern int sysctl_tcp_rfc1337; 247 extern int sysctl_tcp_abort_on_overflow; 248 extern int sysctl_tcp_max_orphans; 249 extern int sysctl_tcp_fack; 250 extern int sysctl_tcp_reordering; 251 extern int sysctl_tcp_max_reordering; 252 extern int sysctl_tcp_dsack; 253 extern long sysctl_tcp_mem[3]; 254 extern int sysctl_tcp_wmem[3]; 255 extern int sysctl_tcp_rmem[3]; 256 extern int sysctl_tcp_app_win; 257 extern int sysctl_tcp_adv_win_scale; 258 extern int sysctl_tcp_frto; 259 extern int sysctl_tcp_nometrics_save; 260 extern int sysctl_tcp_moderate_rcvbuf; 261 extern int sysctl_tcp_tso_win_divisor; 262 extern int sysctl_tcp_workaround_signed_windows; 263 extern int sysctl_tcp_slow_start_after_idle; 264 extern int sysctl_tcp_thin_linear_timeouts; 265 extern int sysctl_tcp_thin_dupack; 266 extern int sysctl_tcp_early_retrans; 267 extern int sysctl_tcp_recovery; 268 #define TCP_RACK_LOSS_DETECTION 0x1 /* Use RACK to detect losses */ 269 270 extern int sysctl_tcp_limit_output_bytes; 271 extern int sysctl_tcp_challenge_ack_limit; 272 extern int sysctl_tcp_min_tso_segs; 273 extern int sysctl_tcp_min_rtt_wlen; 274 extern int sysctl_tcp_autocorking; 275 extern int sysctl_tcp_invalid_ratelimit; 276 extern int sysctl_tcp_pacing_ss_ratio; 277 extern int sysctl_tcp_pacing_ca_ratio; 278 279 extern atomic_long_t tcp_memory_allocated; 280 extern struct percpu_counter tcp_sockets_allocated; 281 extern unsigned long tcp_memory_pressure; 282 283 /* optimized version of sk_under_memory_pressure() for TCP sockets */ 284 static inline bool tcp_under_memory_pressure(const struct sock *sk) 285 { 286 if (mem_cgroup_sockets_enabled && sk->sk_memcg && 287 mem_cgroup_under_socket_pressure(sk->sk_memcg)) 288 return true; 289 290 return tcp_memory_pressure; 291 } 292 /* 293 * The next routines deal with comparing 32 bit unsigned ints 294 * and worry about wraparound (automatic with unsigned arithmetic). 295 */ 296 297 static inline bool before(__u32 seq1, __u32 seq2) 298 { 299 return (__s32)(seq1-seq2) < 0; 300 } 301 #define after(seq2, seq1) before(seq1, seq2) 302 303 /* is s2<=s1<=s3 ? */ 304 static inline bool between(__u32 seq1, __u32 seq2, __u32 seq3) 305 { 306 return seq3 - seq2 >= seq1 - seq2; 307 } 308 309 static inline bool tcp_out_of_memory(struct sock *sk) 310 { 311 if (sk->sk_wmem_queued > SOCK_MIN_SNDBUF && 312 sk_memory_allocated(sk) > sk_prot_mem_limits(sk, 2)) 313 return true; 314 return false; 315 } 316 317 void sk_forced_mem_schedule(struct sock *sk, int size); 318 319 static inline bool tcp_too_many_orphans(struct sock *sk, int shift) 320 { 321 struct percpu_counter *ocp = sk->sk_prot->orphan_count; 322 int orphans = percpu_counter_read_positive(ocp); 323 324 if (orphans << shift > sysctl_tcp_max_orphans) { 325 orphans = percpu_counter_sum_positive(ocp); 326 if (orphans << shift > sysctl_tcp_max_orphans) 327 return true; 328 } 329 return false; 330 } 331 332 bool tcp_check_oom(struct sock *sk, int shift); 333 334 335 extern struct proto tcp_prot; 336 337 #define TCP_INC_STATS(net, field) SNMP_INC_STATS((net)->mib.tcp_statistics, field) 338 #define __TCP_INC_STATS(net, field) __SNMP_INC_STATS((net)->mib.tcp_statistics, field) 339 #define TCP_DEC_STATS(net, field) SNMP_DEC_STATS((net)->mib.tcp_statistics, field) 340 #define TCP_ADD_STATS(net, field, val) SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val) 341 342 void tcp_tasklet_init(void); 343 344 void tcp_v4_err(struct sk_buff *skb, u32); 345 346 void tcp_shutdown(struct sock *sk, int how); 347 348 void tcp_v4_early_demux(struct sk_buff *skb); 349 int tcp_v4_rcv(struct sk_buff *skb); 350 351 int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw); 352 int tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size); 353 int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size); 354 int tcp_sendpage(struct sock *sk, struct page *page, int offset, size_t size, 355 int flags); 356 int tcp_sendpage_locked(struct sock *sk, struct page *page, int offset, 357 size_t size, int flags); 358 ssize_t do_tcp_sendpages(struct sock *sk, struct page *page, int offset, 359 size_t size, int flags); 360 void tcp_release_cb(struct sock *sk); 361 void tcp_wfree(struct sk_buff *skb); 362 void tcp_write_timer_handler(struct sock *sk); 363 void tcp_delack_timer_handler(struct sock *sk); 364 int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg); 365 int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb); 366 void tcp_rcv_established(struct sock *sk, struct sk_buff *skb, 367 const struct tcphdr *th); 368 void tcp_rcv_space_adjust(struct sock *sk); 369 int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp); 370 void tcp_twsk_destructor(struct sock *sk); 371 ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos, 372 struct pipe_inode_info *pipe, size_t len, 373 unsigned int flags); 374 375 static inline void tcp_dec_quickack_mode(struct sock *sk, 376 const unsigned int pkts) 377 { 378 struct inet_connection_sock *icsk = inet_csk(sk); 379 380 if (icsk->icsk_ack.quick) { 381 if (pkts >= icsk->icsk_ack.quick) { 382 icsk->icsk_ack.quick = 0; 383 /* Leaving quickack mode we deflate ATO. */ 384 icsk->icsk_ack.ato = TCP_ATO_MIN; 385 } else 386 icsk->icsk_ack.quick -= pkts; 387 } 388 } 389 390 #define TCP_ECN_OK 1 391 #define TCP_ECN_QUEUE_CWR 2 392 #define TCP_ECN_DEMAND_CWR 4 393 #define TCP_ECN_SEEN 8 394 395 enum tcp_tw_status { 396 TCP_TW_SUCCESS = 0, 397 TCP_TW_RST = 1, 398 TCP_TW_ACK = 2, 399 TCP_TW_SYN = 3 400 }; 401 402 403 enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw, 404 struct sk_buff *skb, 405 const struct tcphdr *th); 406 struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb, 407 struct request_sock *req, bool fastopen); 408 int tcp_child_process(struct sock *parent, struct sock *child, 409 struct sk_buff *skb); 410 void tcp_enter_loss(struct sock *sk); 411 void tcp_cwnd_reduction(struct sock *sk, int newly_acked_sacked, int flag); 412 void tcp_clear_retrans(struct tcp_sock *tp); 413 void tcp_update_metrics(struct sock *sk); 414 void tcp_init_metrics(struct sock *sk); 415 void tcp_metrics_init(void); 416 bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst); 417 void tcp_disable_fack(struct tcp_sock *tp); 418 void tcp_close(struct sock *sk, long timeout); 419 void tcp_init_sock(struct sock *sk); 420 unsigned int tcp_poll(struct file *file, struct socket *sock, 421 struct poll_table_struct *wait); 422 int tcp_getsockopt(struct sock *sk, int level, int optname, 423 char __user *optval, int __user *optlen); 424 int tcp_setsockopt(struct sock *sk, int level, int optname, 425 char __user *optval, unsigned int optlen); 426 int compat_tcp_getsockopt(struct sock *sk, int level, int optname, 427 char __user *optval, int __user *optlen); 428 int compat_tcp_setsockopt(struct sock *sk, int level, int optname, 429 char __user *optval, unsigned int optlen); 430 void tcp_set_keepalive(struct sock *sk, int val); 431 void tcp_syn_ack_timeout(const struct request_sock *req); 432 int tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int nonblock, 433 int flags, int *addr_len); 434 void tcp_parse_options(const struct net *net, const struct sk_buff *skb, 435 struct tcp_options_received *opt_rx, 436 int estab, struct tcp_fastopen_cookie *foc); 437 const u8 *tcp_parse_md5sig_option(const struct tcphdr *th); 438 439 /* 440 * TCP v4 functions exported for the inet6 API 441 */ 442 443 void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb); 444 void tcp_v4_mtu_reduced(struct sock *sk); 445 void tcp_req_err(struct sock *sk, u32 seq, bool abort); 446 int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb); 447 struct sock *tcp_create_openreq_child(const struct sock *sk, 448 struct request_sock *req, 449 struct sk_buff *skb); 450 void tcp_ca_openreq_child(struct sock *sk, const struct dst_entry *dst); 451 struct sock *tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb, 452 struct request_sock *req, 453 struct dst_entry *dst, 454 struct request_sock *req_unhash, 455 bool *own_req); 456 int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb); 457 int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len); 458 int tcp_connect(struct sock *sk); 459 enum tcp_synack_type { 460 TCP_SYNACK_NORMAL, 461 TCP_SYNACK_FASTOPEN, 462 TCP_SYNACK_COOKIE, 463 }; 464 struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst, 465 struct request_sock *req, 466 struct tcp_fastopen_cookie *foc, 467 enum tcp_synack_type synack_type); 468 int tcp_disconnect(struct sock *sk, int flags); 469 470 void tcp_finish_connect(struct sock *sk, struct sk_buff *skb); 471 int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size); 472 void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb); 473 474 /* From syncookies.c */ 475 struct sock *tcp_get_cookie_sock(struct sock *sk, struct sk_buff *skb, 476 struct request_sock *req, 477 struct dst_entry *dst, u32 tsoff); 478 int __cookie_v4_check(const struct iphdr *iph, const struct tcphdr *th, 479 u32 cookie); 480 struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb); 481 #ifdef CONFIG_SYN_COOKIES 482 483 /* Syncookies use a monotonic timer which increments every 60 seconds. 484 * This counter is used both as a hash input and partially encoded into 485 * the cookie value. A cookie is only validated further if the delta 486 * between the current counter value and the encoded one is less than this, 487 * i.e. a sent cookie is valid only at most for 2*60 seconds (or less if 488 * the counter advances immediately after a cookie is generated). 489 */ 490 #define MAX_SYNCOOKIE_AGE 2 491 #define TCP_SYNCOOKIE_PERIOD (60 * HZ) 492 #define TCP_SYNCOOKIE_VALID (MAX_SYNCOOKIE_AGE * TCP_SYNCOOKIE_PERIOD) 493 494 /* syncookies: remember time of last synqueue overflow 495 * But do not dirty this field too often (once per second is enough) 496 * It is racy as we do not hold a lock, but race is very minor. 497 */ 498 static inline void tcp_synq_overflow(const struct sock *sk) 499 { 500 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp; 501 unsigned long now = jiffies; 502 503 if (time_after(now, last_overflow + HZ)) 504 tcp_sk(sk)->rx_opt.ts_recent_stamp = now; 505 } 506 507 /* syncookies: no recent synqueue overflow on this listening socket? */ 508 static inline bool tcp_synq_no_recent_overflow(const struct sock *sk) 509 { 510 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp; 511 512 return time_after(jiffies, last_overflow + TCP_SYNCOOKIE_VALID); 513 } 514 515 static inline u32 tcp_cookie_time(void) 516 { 517 u64 val = get_jiffies_64(); 518 519 do_div(val, TCP_SYNCOOKIE_PERIOD); 520 return val; 521 } 522 523 u32 __cookie_v4_init_sequence(const struct iphdr *iph, const struct tcphdr *th, 524 u16 *mssp); 525 __u32 cookie_v4_init_sequence(const struct sk_buff *skb, __u16 *mss); 526 u64 cookie_init_timestamp(struct request_sock *req); 527 bool cookie_timestamp_decode(const struct net *net, 528 struct tcp_options_received *opt); 529 bool cookie_ecn_ok(const struct tcp_options_received *opt, 530 const struct net *net, const struct dst_entry *dst); 531 532 /* From net/ipv6/syncookies.c */ 533 int __cookie_v6_check(const struct ipv6hdr *iph, const struct tcphdr *th, 534 u32 cookie); 535 struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb); 536 537 u32 __cookie_v6_init_sequence(const struct ipv6hdr *iph, 538 const struct tcphdr *th, u16 *mssp); 539 __u32 cookie_v6_init_sequence(const struct sk_buff *skb, __u16 *mss); 540 #endif 541 /* tcp_output.c */ 542 543 u32 tcp_tso_autosize(const struct sock *sk, unsigned int mss_now, 544 int min_tso_segs); 545 void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss, 546 int nonagle); 547 bool tcp_may_send_now(struct sock *sk); 548 int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs); 549 int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs); 550 void tcp_retransmit_timer(struct sock *sk); 551 void tcp_xmit_retransmit_queue(struct sock *); 552 void tcp_simple_retransmit(struct sock *); 553 void tcp_enter_recovery(struct sock *sk, bool ece_ack); 554 int tcp_trim_head(struct sock *, struct sk_buff *, u32); 555 int tcp_fragment(struct sock *, struct sk_buff *, u32, unsigned int, gfp_t); 556 557 void tcp_send_probe0(struct sock *); 558 void tcp_send_partial(struct sock *); 559 int tcp_write_wakeup(struct sock *, int mib); 560 void tcp_send_fin(struct sock *sk); 561 void tcp_send_active_reset(struct sock *sk, gfp_t priority); 562 int tcp_send_synack(struct sock *); 563 void tcp_push_one(struct sock *, unsigned int mss_now); 564 void tcp_send_ack(struct sock *sk); 565 void tcp_send_delayed_ack(struct sock *sk); 566 void tcp_send_loss_probe(struct sock *sk); 567 bool tcp_schedule_loss_probe(struct sock *sk); 568 void tcp_skb_collapse_tstamp(struct sk_buff *skb, 569 const struct sk_buff *next_skb); 570 571 /* tcp_input.c */ 572 void tcp_rearm_rto(struct sock *sk); 573 void tcp_synack_rtt_meas(struct sock *sk, struct request_sock *req); 574 void tcp_reset(struct sock *sk); 575 void tcp_skb_mark_lost_uncond_verify(struct tcp_sock *tp, struct sk_buff *skb); 576 void tcp_fin(struct sock *sk); 577 578 /* tcp_timer.c */ 579 void tcp_init_xmit_timers(struct sock *); 580 static inline void tcp_clear_xmit_timers(struct sock *sk) 581 { 582 hrtimer_cancel(&tcp_sk(sk)->pacing_timer); 583 inet_csk_clear_xmit_timers(sk); 584 } 585 586 unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu); 587 unsigned int tcp_current_mss(struct sock *sk); 588 589 /* Bound MSS / TSO packet size with the half of the window */ 590 static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize) 591 { 592 int cutoff; 593 594 /* When peer uses tiny windows, there is no use in packetizing 595 * to sub-MSS pieces for the sake of SWS or making sure there 596 * are enough packets in the pipe for fast recovery. 597 * 598 * On the other hand, for extremely large MSS devices, handling 599 * smaller than MSS windows in this way does make sense. 600 */ 601 if (tp->max_window > TCP_MSS_DEFAULT) 602 cutoff = (tp->max_window >> 1); 603 else 604 cutoff = tp->max_window; 605 606 if (cutoff && pktsize > cutoff) 607 return max_t(int, cutoff, 68U - tp->tcp_header_len); 608 else 609 return pktsize; 610 } 611 612 /* tcp.c */ 613 void tcp_get_info(struct sock *, struct tcp_info *); 614 615 /* Read 'sendfile()'-style from a TCP socket */ 616 int tcp_read_sock(struct sock *sk, read_descriptor_t *desc, 617 sk_read_actor_t recv_actor); 618 619 void tcp_initialize_rcv_mss(struct sock *sk); 620 621 int tcp_mtu_to_mss(struct sock *sk, int pmtu); 622 int tcp_mss_to_mtu(struct sock *sk, int mss); 623 void tcp_mtup_init(struct sock *sk); 624 void tcp_init_buffer_space(struct sock *sk); 625 626 static inline void tcp_bound_rto(const struct sock *sk) 627 { 628 if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX) 629 inet_csk(sk)->icsk_rto = TCP_RTO_MAX; 630 } 631 632 static inline u32 __tcp_set_rto(const struct tcp_sock *tp) 633 { 634 return usecs_to_jiffies((tp->srtt_us >> 3) + tp->rttvar_us); 635 } 636 637 static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd) 638 { 639 tp->pred_flags = htonl((tp->tcp_header_len << 26) | 640 ntohl(TCP_FLAG_ACK) | 641 snd_wnd); 642 } 643 644 static inline void tcp_fast_path_on(struct tcp_sock *tp) 645 { 646 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale); 647 } 648 649 static inline void tcp_fast_path_check(struct sock *sk) 650 { 651 struct tcp_sock *tp = tcp_sk(sk); 652 653 if (RB_EMPTY_ROOT(&tp->out_of_order_queue) && 654 tp->rcv_wnd && 655 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf && 656 !tp->urg_data) 657 tcp_fast_path_on(tp); 658 } 659 660 /* Compute the actual rto_min value */ 661 static inline u32 tcp_rto_min(struct sock *sk) 662 { 663 const struct dst_entry *dst = __sk_dst_get(sk); 664 u32 rto_min = TCP_RTO_MIN; 665 666 if (dst && dst_metric_locked(dst, RTAX_RTO_MIN)) 667 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN); 668 return rto_min; 669 } 670 671 static inline u32 tcp_rto_min_us(struct sock *sk) 672 { 673 return jiffies_to_usecs(tcp_rto_min(sk)); 674 } 675 676 static inline bool tcp_ca_dst_locked(const struct dst_entry *dst) 677 { 678 return dst_metric_locked(dst, RTAX_CC_ALGO); 679 } 680 681 /* Minimum RTT in usec. ~0 means not available. */ 682 static inline u32 tcp_min_rtt(const struct tcp_sock *tp) 683 { 684 return minmax_get(&tp->rtt_min); 685 } 686 687 /* Compute the actual receive window we are currently advertising. 688 * Rcv_nxt can be after the window if our peer push more data 689 * than the offered window. 690 */ 691 static inline u32 tcp_receive_window(const struct tcp_sock *tp) 692 { 693 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt; 694 695 if (win < 0) 696 win = 0; 697 return (u32) win; 698 } 699 700 /* Choose a new window, without checks for shrinking, and without 701 * scaling applied to the result. The caller does these things 702 * if necessary. This is a "raw" window selection. 703 */ 704 u32 __tcp_select_window(struct sock *sk); 705 706 void tcp_send_window_probe(struct sock *sk); 707 708 /* TCP uses 32bit jiffies to save some space. 709 * Note that this is different from tcp_time_stamp, which 710 * historically has been the same until linux-4.13. 711 */ 712 #define tcp_jiffies32 ((u32)jiffies) 713 714 /* 715 * Deliver a 32bit value for TCP timestamp option (RFC 7323) 716 * It is no longer tied to jiffies, but to 1 ms clock. 717 * Note: double check if you want to use tcp_jiffies32 instead of this. 718 */ 719 #define TCP_TS_HZ 1000 720 721 static inline u64 tcp_clock_ns(void) 722 { 723 return local_clock(); 724 } 725 726 static inline u64 tcp_clock_us(void) 727 { 728 return div_u64(tcp_clock_ns(), NSEC_PER_USEC); 729 } 730 731 /* This should only be used in contexts where tp->tcp_mstamp is up to date */ 732 static inline u32 tcp_time_stamp(const struct tcp_sock *tp) 733 { 734 return div_u64(tp->tcp_mstamp, USEC_PER_SEC / TCP_TS_HZ); 735 } 736 737 /* Could use tcp_clock_us() / 1000, but this version uses a single divide */ 738 static inline u32 tcp_time_stamp_raw(void) 739 { 740 return div_u64(tcp_clock_ns(), NSEC_PER_SEC / TCP_TS_HZ); 741 } 742 743 744 /* Refresh 1us clock of a TCP socket, 745 * ensuring monotically increasing values. 746 */ 747 static inline void tcp_mstamp_refresh(struct tcp_sock *tp) 748 { 749 u64 val = tcp_clock_us(); 750 751 if (val > tp->tcp_mstamp) 752 tp->tcp_mstamp = val; 753 } 754 755 static inline u32 tcp_stamp_us_delta(u64 t1, u64 t0) 756 { 757 return max_t(s64, t1 - t0, 0); 758 } 759 760 static inline u32 tcp_skb_timestamp(const struct sk_buff *skb) 761 { 762 return div_u64(skb->skb_mstamp, USEC_PER_SEC / TCP_TS_HZ); 763 } 764 765 766 #define tcp_flag_byte(th) (((u_int8_t *)th)[13]) 767 768 #define TCPHDR_FIN 0x01 769 #define TCPHDR_SYN 0x02 770 #define TCPHDR_RST 0x04 771 #define TCPHDR_PSH 0x08 772 #define TCPHDR_ACK 0x10 773 #define TCPHDR_URG 0x20 774 #define TCPHDR_ECE 0x40 775 #define TCPHDR_CWR 0x80 776 777 #define TCPHDR_SYN_ECN (TCPHDR_SYN | TCPHDR_ECE | TCPHDR_CWR) 778 779 /* This is what the send packet queuing engine uses to pass 780 * TCP per-packet control information to the transmission code. 781 * We also store the host-order sequence numbers in here too. 782 * This is 44 bytes if IPV6 is enabled. 783 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately. 784 */ 785 struct tcp_skb_cb { 786 __u32 seq; /* Starting sequence number */ 787 __u32 end_seq; /* SEQ + FIN + SYN + datalen */ 788 union { 789 /* Note : tcp_tw_isn is used in input path only 790 * (isn chosen by tcp_timewait_state_process()) 791 * 792 * tcp_gso_segs/size are used in write queue only, 793 * cf tcp_skb_pcount()/tcp_skb_mss() 794 */ 795 __u32 tcp_tw_isn; 796 struct { 797 u16 tcp_gso_segs; 798 u16 tcp_gso_size; 799 }; 800 801 /* Used to stash the receive timestamp while this skb is in the 802 * out of order queue, as skb->tstamp is overwritten by the 803 * rbnode. 804 */ 805 ktime_t swtstamp; 806 }; 807 __u8 tcp_flags; /* TCP header flags. (tcp[13]) */ 808 809 __u8 sacked; /* State flags for SACK/FACK. */ 810 #define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */ 811 #define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */ 812 #define TCPCB_LOST 0x04 /* SKB is lost */ 813 #define TCPCB_TAGBITS 0x07 /* All tag bits */ 814 #define TCPCB_REPAIRED 0x10 /* SKB repaired (no skb_mstamp) */ 815 #define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */ 816 #define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS| \ 817 TCPCB_REPAIRED) 818 819 __u8 ip_dsfield; /* IPv4 tos or IPv6 dsfield */ 820 __u8 txstamp_ack:1, /* Record TX timestamp for ack? */ 821 eor:1, /* Is skb MSG_EOR marked? */ 822 has_rxtstamp:1, /* SKB has a RX timestamp */ 823 unused:5; 824 __u32 ack_seq; /* Sequence number ACK'd */ 825 union { 826 struct { 827 /* There is space for up to 24 bytes */ 828 __u32 in_flight:30,/* Bytes in flight at transmit */ 829 is_app_limited:1, /* cwnd not fully used? */ 830 unused:1; 831 /* pkts S/ACKed so far upon tx of skb, incl retrans: */ 832 __u32 delivered; 833 /* start of send pipeline phase */ 834 u64 first_tx_mstamp; 835 /* when we reached the "delivered" count */ 836 u64 delivered_mstamp; 837 } tx; /* only used for outgoing skbs */ 838 union { 839 struct inet_skb_parm h4; 840 #if IS_ENABLED(CONFIG_IPV6) 841 struct inet6_skb_parm h6; 842 #endif 843 } header; /* For incoming skbs */ 844 }; 845 }; 846 847 #define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0])) 848 849 850 #if IS_ENABLED(CONFIG_IPV6) 851 /* This is the variant of inet6_iif() that must be used by TCP, 852 * as TCP moves IP6CB into a different location in skb->cb[] 853 */ 854 static inline int tcp_v6_iif(const struct sk_buff *skb) 855 { 856 bool l3_slave = ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags); 857 858 return l3_slave ? skb->skb_iif : TCP_SKB_CB(skb)->header.h6.iif; 859 } 860 861 /* TCP_SKB_CB reference means this can not be used from early demux */ 862 static inline int tcp_v6_sdif(const struct sk_buff *skb) 863 { 864 #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV) 865 if (skb && ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags)) 866 return TCP_SKB_CB(skb)->header.h6.iif; 867 #endif 868 return 0; 869 } 870 #endif 871 872 /* TCP_SKB_CB reference means this can not be used from early demux */ 873 static inline bool inet_exact_dif_match(struct net *net, struct sk_buff *skb) 874 { 875 #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV) 876 if (!net->ipv4.sysctl_tcp_l3mdev_accept && 877 skb && ipv4_l3mdev_skb(TCP_SKB_CB(skb)->header.h4.flags)) 878 return true; 879 #endif 880 return false; 881 } 882 883 /* TCP_SKB_CB reference means this can not be used from early demux */ 884 static inline int tcp_v4_sdif(struct sk_buff *skb) 885 { 886 #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV) 887 if (skb && ipv4_l3mdev_skb(TCP_SKB_CB(skb)->header.h4.flags)) 888 return TCP_SKB_CB(skb)->header.h4.iif; 889 #endif 890 return 0; 891 } 892 893 /* Due to TSO, an SKB can be composed of multiple actual 894 * packets. To keep these tracked properly, we use this. 895 */ 896 static inline int tcp_skb_pcount(const struct sk_buff *skb) 897 { 898 return TCP_SKB_CB(skb)->tcp_gso_segs; 899 } 900 901 static inline void tcp_skb_pcount_set(struct sk_buff *skb, int segs) 902 { 903 TCP_SKB_CB(skb)->tcp_gso_segs = segs; 904 } 905 906 static inline void tcp_skb_pcount_add(struct sk_buff *skb, int segs) 907 { 908 TCP_SKB_CB(skb)->tcp_gso_segs += segs; 909 } 910 911 /* This is valid iff skb is in write queue and tcp_skb_pcount() > 1. */ 912 static inline int tcp_skb_mss(const struct sk_buff *skb) 913 { 914 return TCP_SKB_CB(skb)->tcp_gso_size; 915 } 916 917 static inline bool tcp_skb_can_collapse_to(const struct sk_buff *skb) 918 { 919 return likely(!TCP_SKB_CB(skb)->eor); 920 } 921 922 /* Events passed to congestion control interface */ 923 enum tcp_ca_event { 924 CA_EVENT_TX_START, /* first transmit when no packets in flight */ 925 CA_EVENT_CWND_RESTART, /* congestion window restart */ 926 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */ 927 CA_EVENT_LOSS, /* loss timeout */ 928 CA_EVENT_ECN_NO_CE, /* ECT set, but not CE marked */ 929 CA_EVENT_ECN_IS_CE, /* received CE marked IP packet */ 930 CA_EVENT_DELAYED_ACK, /* Delayed ack is sent */ 931 CA_EVENT_NON_DELAYED_ACK, 932 }; 933 934 /* Information about inbound ACK, passed to cong_ops->in_ack_event() */ 935 enum tcp_ca_ack_event_flags { 936 CA_ACK_SLOWPATH = (1 << 0), /* In slow path processing */ 937 CA_ACK_WIN_UPDATE = (1 << 1), /* ACK updated window */ 938 CA_ACK_ECE = (1 << 2), /* ECE bit is set on ack */ 939 }; 940 941 /* 942 * Interface for adding new TCP congestion control handlers 943 */ 944 #define TCP_CA_NAME_MAX 16 945 #define TCP_CA_MAX 128 946 #define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX) 947 948 #define TCP_CA_UNSPEC 0 949 950 /* Algorithm can be set on socket without CAP_NET_ADMIN privileges */ 951 #define TCP_CONG_NON_RESTRICTED 0x1 952 /* Requires ECN/ECT set on all packets */ 953 #define TCP_CONG_NEEDS_ECN 0x2 954 955 union tcp_cc_info; 956 957 struct ack_sample { 958 u32 pkts_acked; 959 s32 rtt_us; 960 u32 in_flight; 961 }; 962 963 /* A rate sample measures the number of (original/retransmitted) data 964 * packets delivered "delivered" over an interval of time "interval_us". 965 * The tcp_rate.c code fills in the rate sample, and congestion 966 * control modules that define a cong_control function to run at the end 967 * of ACK processing can optionally chose to consult this sample when 968 * setting cwnd and pacing rate. 969 * A sample is invalid if "delivered" or "interval_us" is negative. 970 */ 971 struct rate_sample { 972 u64 prior_mstamp; /* starting timestamp for interval */ 973 u32 prior_delivered; /* tp->delivered at "prior_mstamp" */ 974 s32 delivered; /* number of packets delivered over interval */ 975 long interval_us; /* time for tp->delivered to incr "delivered" */ 976 long rtt_us; /* RTT of last (S)ACKed packet (or -1) */ 977 int losses; /* number of packets marked lost upon ACK */ 978 u32 acked_sacked; /* number of packets newly (S)ACKed upon ACK */ 979 u32 prior_in_flight; /* in flight before this ACK */ 980 bool is_app_limited; /* is sample from packet with bubble in pipe? */ 981 bool is_retrans; /* is sample from retransmission? */ 982 }; 983 984 struct tcp_congestion_ops { 985 struct list_head list; 986 u32 key; 987 u32 flags; 988 989 /* initialize private data (optional) */ 990 void (*init)(struct sock *sk); 991 /* cleanup private data (optional) */ 992 void (*release)(struct sock *sk); 993 994 /* return slow start threshold (required) */ 995 u32 (*ssthresh)(struct sock *sk); 996 /* do new cwnd calculation (required) */ 997 void (*cong_avoid)(struct sock *sk, u32 ack, u32 acked); 998 /* call before changing ca_state (optional) */ 999 void (*set_state)(struct sock *sk, u8 new_state); 1000 /* call when cwnd event occurs (optional) */ 1001 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev); 1002 /* call when ack arrives (optional) */ 1003 void (*in_ack_event)(struct sock *sk, u32 flags); 1004 /* new value of cwnd after loss (required) */ 1005 u32 (*undo_cwnd)(struct sock *sk); 1006 /* hook for packet ack accounting (optional) */ 1007 void (*pkts_acked)(struct sock *sk, const struct ack_sample *sample); 1008 /* suggest number of segments for each skb to transmit (optional) */ 1009 u32 (*tso_segs_goal)(struct sock *sk); 1010 /* returns the multiplier used in tcp_sndbuf_expand (optional) */ 1011 u32 (*sndbuf_expand)(struct sock *sk); 1012 /* call when packets are delivered to update cwnd and pacing rate, 1013 * after all the ca_state processing. (optional) 1014 */ 1015 void (*cong_control)(struct sock *sk, const struct rate_sample *rs); 1016 /* get info for inet_diag (optional) */ 1017 size_t (*get_info)(struct sock *sk, u32 ext, int *attr, 1018 union tcp_cc_info *info); 1019 1020 char name[TCP_CA_NAME_MAX]; 1021 struct module *owner; 1022 }; 1023 1024 int tcp_register_congestion_control(struct tcp_congestion_ops *type); 1025 void tcp_unregister_congestion_control(struct tcp_congestion_ops *type); 1026 1027 void tcp_assign_congestion_control(struct sock *sk); 1028 void tcp_init_congestion_control(struct sock *sk); 1029 void tcp_cleanup_congestion_control(struct sock *sk); 1030 int tcp_set_default_congestion_control(const char *name); 1031 void tcp_get_default_congestion_control(char *name); 1032 void tcp_get_available_congestion_control(char *buf, size_t len); 1033 void tcp_get_allowed_congestion_control(char *buf, size_t len); 1034 int tcp_set_allowed_congestion_control(char *allowed); 1035 int tcp_set_congestion_control(struct sock *sk, const char *name, bool load, bool reinit); 1036 u32 tcp_slow_start(struct tcp_sock *tp, u32 acked); 1037 void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w, u32 acked); 1038 1039 u32 tcp_reno_ssthresh(struct sock *sk); 1040 u32 tcp_reno_undo_cwnd(struct sock *sk); 1041 void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 acked); 1042 extern struct tcp_congestion_ops tcp_reno; 1043 1044 struct tcp_congestion_ops *tcp_ca_find_key(u32 key); 1045 u32 tcp_ca_get_key_by_name(const char *name, bool *ecn_ca); 1046 #ifdef CONFIG_INET 1047 char *tcp_ca_get_name_by_key(u32 key, char *buffer); 1048 #else 1049 static inline char *tcp_ca_get_name_by_key(u32 key, char *buffer) 1050 { 1051 return NULL; 1052 } 1053 #endif 1054 1055 static inline bool tcp_ca_needs_ecn(const struct sock *sk) 1056 { 1057 const struct inet_connection_sock *icsk = inet_csk(sk); 1058 1059 return icsk->icsk_ca_ops->flags & TCP_CONG_NEEDS_ECN; 1060 } 1061 1062 static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state) 1063 { 1064 struct inet_connection_sock *icsk = inet_csk(sk); 1065 1066 if (icsk->icsk_ca_ops->set_state) 1067 icsk->icsk_ca_ops->set_state(sk, ca_state); 1068 icsk->icsk_ca_state = ca_state; 1069 } 1070 1071 static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event) 1072 { 1073 const struct inet_connection_sock *icsk = inet_csk(sk); 1074 1075 if (icsk->icsk_ca_ops->cwnd_event) 1076 icsk->icsk_ca_ops->cwnd_event(sk, event); 1077 } 1078 1079 /* From tcp_rate.c */ 1080 void tcp_rate_skb_sent(struct sock *sk, struct sk_buff *skb); 1081 void tcp_rate_skb_delivered(struct sock *sk, struct sk_buff *skb, 1082 struct rate_sample *rs); 1083 void tcp_rate_gen(struct sock *sk, u32 delivered, u32 lost, 1084 struct rate_sample *rs); 1085 void tcp_rate_check_app_limited(struct sock *sk); 1086 1087 /* These functions determine how the current flow behaves in respect of SACK 1088 * handling. SACK is negotiated with the peer, and therefore it can vary 1089 * between different flows. 1090 * 1091 * tcp_is_sack - SACK enabled 1092 * tcp_is_reno - No SACK 1093 * tcp_is_fack - FACK enabled, implies SACK enabled 1094 */ 1095 static inline int tcp_is_sack(const struct tcp_sock *tp) 1096 { 1097 return tp->rx_opt.sack_ok; 1098 } 1099 1100 static inline bool tcp_is_reno(const struct tcp_sock *tp) 1101 { 1102 return !tcp_is_sack(tp); 1103 } 1104 1105 static inline bool tcp_is_fack(const struct tcp_sock *tp) 1106 { 1107 return tp->rx_opt.sack_ok & TCP_FACK_ENABLED; 1108 } 1109 1110 static inline void tcp_enable_fack(struct tcp_sock *tp) 1111 { 1112 tp->rx_opt.sack_ok |= TCP_FACK_ENABLED; 1113 } 1114 1115 static inline unsigned int tcp_left_out(const struct tcp_sock *tp) 1116 { 1117 return tp->sacked_out + tp->lost_out; 1118 } 1119 1120 /* This determines how many packets are "in the network" to the best 1121 * of our knowledge. In many cases it is conservative, but where 1122 * detailed information is available from the receiver (via SACK 1123 * blocks etc.) we can make more aggressive calculations. 1124 * 1125 * Use this for decisions involving congestion control, use just 1126 * tp->packets_out to determine if the send queue is empty or not. 1127 * 1128 * Read this equation as: 1129 * 1130 * "Packets sent once on transmission queue" MINUS 1131 * "Packets left network, but not honestly ACKed yet" PLUS 1132 * "Packets fast retransmitted" 1133 */ 1134 static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp) 1135 { 1136 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out; 1137 } 1138 1139 #define TCP_INFINITE_SSTHRESH 0x7fffffff 1140 1141 static inline bool tcp_in_slow_start(const struct tcp_sock *tp) 1142 { 1143 return tp->snd_cwnd < tp->snd_ssthresh; 1144 } 1145 1146 static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp) 1147 { 1148 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH; 1149 } 1150 1151 static inline bool tcp_in_cwnd_reduction(const struct sock *sk) 1152 { 1153 return (TCPF_CA_CWR | TCPF_CA_Recovery) & 1154 (1 << inet_csk(sk)->icsk_ca_state); 1155 } 1156 1157 /* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd. 1158 * The exception is cwnd reduction phase, when cwnd is decreasing towards 1159 * ssthresh. 1160 */ 1161 static inline __u32 tcp_current_ssthresh(const struct sock *sk) 1162 { 1163 const struct tcp_sock *tp = tcp_sk(sk); 1164 1165 if (tcp_in_cwnd_reduction(sk)) 1166 return tp->snd_ssthresh; 1167 else 1168 return max(tp->snd_ssthresh, 1169 ((tp->snd_cwnd >> 1) + 1170 (tp->snd_cwnd >> 2))); 1171 } 1172 1173 /* Use define here intentionally to get WARN_ON location shown at the caller */ 1174 #define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out) 1175 1176 void tcp_enter_cwr(struct sock *sk); 1177 __u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst); 1178 1179 /* The maximum number of MSS of available cwnd for which TSO defers 1180 * sending if not using sysctl_tcp_tso_win_divisor. 1181 */ 1182 static inline __u32 tcp_max_tso_deferred_mss(const struct tcp_sock *tp) 1183 { 1184 return 3; 1185 } 1186 1187 /* Returns end sequence number of the receiver's advertised window */ 1188 static inline u32 tcp_wnd_end(const struct tcp_sock *tp) 1189 { 1190 return tp->snd_una + tp->snd_wnd; 1191 } 1192 1193 /* We follow the spirit of RFC2861 to validate cwnd but implement a more 1194 * flexible approach. The RFC suggests cwnd should not be raised unless 1195 * it was fully used previously. And that's exactly what we do in 1196 * congestion avoidance mode. But in slow start we allow cwnd to grow 1197 * as long as the application has used half the cwnd. 1198 * Example : 1199 * cwnd is 10 (IW10), but application sends 9 frames. 1200 * We allow cwnd to reach 18 when all frames are ACKed. 1201 * This check is safe because it's as aggressive as slow start which already 1202 * risks 100% overshoot. The advantage is that we discourage application to 1203 * either send more filler packets or data to artificially blow up the cwnd 1204 * usage, and allow application-limited process to probe bw more aggressively. 1205 */ 1206 static inline bool tcp_is_cwnd_limited(const struct sock *sk) 1207 { 1208 const struct tcp_sock *tp = tcp_sk(sk); 1209 1210 /* If in slow start, ensure cwnd grows to twice what was ACKed. */ 1211 if (tcp_in_slow_start(tp)) 1212 return tp->snd_cwnd < 2 * tp->max_packets_out; 1213 1214 return tp->is_cwnd_limited; 1215 } 1216 1217 /* Something is really bad, we could not queue an additional packet, 1218 * because qdisc is full or receiver sent a 0 window. 1219 * We do not want to add fuel to the fire, or abort too early, 1220 * so make sure the timer we arm now is at least 200ms in the future, 1221 * regardless of current icsk_rto value (as it could be ~2ms) 1222 */ 1223 static inline unsigned long tcp_probe0_base(const struct sock *sk) 1224 { 1225 return max_t(unsigned long, inet_csk(sk)->icsk_rto, TCP_RTO_MIN); 1226 } 1227 1228 /* Variant of inet_csk_rto_backoff() used for zero window probes */ 1229 static inline unsigned long tcp_probe0_when(const struct sock *sk, 1230 unsigned long max_when) 1231 { 1232 u64 when = (u64)tcp_probe0_base(sk) << inet_csk(sk)->icsk_backoff; 1233 1234 return (unsigned long)min_t(u64, when, max_when); 1235 } 1236 1237 static inline void tcp_check_probe_timer(struct sock *sk) 1238 { 1239 if (!tcp_sk(sk)->packets_out && !inet_csk(sk)->icsk_pending) 1240 inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0, 1241 tcp_probe0_base(sk), TCP_RTO_MAX); 1242 } 1243 1244 static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq) 1245 { 1246 tp->snd_wl1 = seq; 1247 } 1248 1249 static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq) 1250 { 1251 tp->snd_wl1 = seq; 1252 } 1253 1254 /* 1255 * Calculate(/check) TCP checksum 1256 */ 1257 static inline __sum16 tcp_v4_check(int len, __be32 saddr, 1258 __be32 daddr, __wsum base) 1259 { 1260 return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base); 1261 } 1262 1263 static inline __sum16 __tcp_checksum_complete(struct sk_buff *skb) 1264 { 1265 return __skb_checksum_complete(skb); 1266 } 1267 1268 static inline bool tcp_checksum_complete(struct sk_buff *skb) 1269 { 1270 return !skb_csum_unnecessary(skb) && 1271 __tcp_checksum_complete(skb); 1272 } 1273 1274 bool tcp_add_backlog(struct sock *sk, struct sk_buff *skb); 1275 int tcp_filter(struct sock *sk, struct sk_buff *skb); 1276 1277 #undef STATE_TRACE 1278 1279 #ifdef STATE_TRACE 1280 static const char *statename[]={ 1281 "Unused","Established","Syn Sent","Syn Recv", 1282 "Fin Wait 1","Fin Wait 2","Time Wait", "Close", 1283 "Close Wait","Last ACK","Listen","Closing" 1284 }; 1285 #endif 1286 void tcp_set_state(struct sock *sk, int state); 1287 1288 void tcp_done(struct sock *sk); 1289 1290 int tcp_abort(struct sock *sk, int err); 1291 1292 static inline void tcp_sack_reset(struct tcp_options_received *rx_opt) 1293 { 1294 rx_opt->dsack = 0; 1295 rx_opt->num_sacks = 0; 1296 } 1297 1298 u32 tcp_default_init_rwnd(u32 mss); 1299 void tcp_cwnd_restart(struct sock *sk, s32 delta); 1300 1301 static inline void tcp_slow_start_after_idle_check(struct sock *sk) 1302 { 1303 const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops; 1304 struct tcp_sock *tp = tcp_sk(sk); 1305 s32 delta; 1306 1307 if (!sysctl_tcp_slow_start_after_idle || tp->packets_out || 1308 ca_ops->cong_control) 1309 return; 1310 delta = tcp_jiffies32 - tp->lsndtime; 1311 if (delta > inet_csk(sk)->icsk_rto) 1312 tcp_cwnd_restart(sk, delta); 1313 } 1314 1315 /* Determine a window scaling and initial window to offer. */ 1316 void tcp_select_initial_window(int __space, __u32 mss, __u32 *rcv_wnd, 1317 __u32 *window_clamp, int wscale_ok, 1318 __u8 *rcv_wscale, __u32 init_rcv_wnd); 1319 1320 static inline int tcp_win_from_space(int space) 1321 { 1322 int tcp_adv_win_scale = sysctl_tcp_adv_win_scale; 1323 1324 return tcp_adv_win_scale <= 0 ? 1325 (space>>(-tcp_adv_win_scale)) : 1326 space - (space>>tcp_adv_win_scale); 1327 } 1328 1329 /* Note: caller must be prepared to deal with negative returns */ 1330 static inline int tcp_space(const struct sock *sk) 1331 { 1332 return tcp_win_from_space(sk->sk_rcvbuf - 1333 atomic_read(&sk->sk_rmem_alloc)); 1334 } 1335 1336 static inline int tcp_full_space(const struct sock *sk) 1337 { 1338 return tcp_win_from_space(sk->sk_rcvbuf); 1339 } 1340 1341 extern void tcp_openreq_init_rwin(struct request_sock *req, 1342 const struct sock *sk_listener, 1343 const struct dst_entry *dst); 1344 1345 void tcp_enter_memory_pressure(struct sock *sk); 1346 void tcp_leave_memory_pressure(struct sock *sk); 1347 1348 static inline int keepalive_intvl_when(const struct tcp_sock *tp) 1349 { 1350 struct net *net = sock_net((struct sock *)tp); 1351 1352 return tp->keepalive_intvl ? : net->ipv4.sysctl_tcp_keepalive_intvl; 1353 } 1354 1355 static inline int keepalive_time_when(const struct tcp_sock *tp) 1356 { 1357 struct net *net = sock_net((struct sock *)tp); 1358 1359 return tp->keepalive_time ? : net->ipv4.sysctl_tcp_keepalive_time; 1360 } 1361 1362 static inline int keepalive_probes(const struct tcp_sock *tp) 1363 { 1364 struct net *net = sock_net((struct sock *)tp); 1365 1366 return tp->keepalive_probes ? : net->ipv4.sysctl_tcp_keepalive_probes; 1367 } 1368 1369 static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp) 1370 { 1371 const struct inet_connection_sock *icsk = &tp->inet_conn; 1372 1373 return min_t(u32, tcp_jiffies32 - icsk->icsk_ack.lrcvtime, 1374 tcp_jiffies32 - tp->rcv_tstamp); 1375 } 1376 1377 static inline int tcp_fin_time(const struct sock *sk) 1378 { 1379 int fin_timeout = tcp_sk(sk)->linger2 ? : sock_net(sk)->ipv4.sysctl_tcp_fin_timeout; 1380 const int rto = inet_csk(sk)->icsk_rto; 1381 1382 if (fin_timeout < (rto << 2) - (rto >> 1)) 1383 fin_timeout = (rto << 2) - (rto >> 1); 1384 1385 return fin_timeout; 1386 } 1387 1388 static inline bool tcp_paws_check(const struct tcp_options_received *rx_opt, 1389 int paws_win) 1390 { 1391 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win) 1392 return true; 1393 if (unlikely(get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS)) 1394 return true; 1395 /* 1396 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0, 1397 * then following tcp messages have valid values. Ignore 0 value, 1398 * or else 'negative' tsval might forbid us to accept their packets. 1399 */ 1400 if (!rx_opt->ts_recent) 1401 return true; 1402 return false; 1403 } 1404 1405 static inline bool tcp_paws_reject(const struct tcp_options_received *rx_opt, 1406 int rst) 1407 { 1408 if (tcp_paws_check(rx_opt, 0)) 1409 return false; 1410 1411 /* RST segments are not recommended to carry timestamp, 1412 and, if they do, it is recommended to ignore PAWS because 1413 "their cleanup function should take precedence over timestamps." 1414 Certainly, it is mistake. It is necessary to understand the reasons 1415 of this constraint to relax it: if peer reboots, clock may go 1416 out-of-sync and half-open connections will not be reset. 1417 Actually, the problem would be not existing if all 1418 the implementations followed draft about maintaining clock 1419 via reboots. Linux-2.2 DOES NOT! 1420 1421 However, we can relax time bounds for RST segments to MSL. 1422 */ 1423 if (rst && get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_MSL) 1424 return false; 1425 return true; 1426 } 1427 1428 bool tcp_oow_rate_limited(struct net *net, const struct sk_buff *skb, 1429 int mib_idx, u32 *last_oow_ack_time); 1430 1431 static inline void tcp_mib_init(struct net *net) 1432 { 1433 /* See RFC 2012 */ 1434 TCP_ADD_STATS(net, TCP_MIB_RTOALGORITHM, 1); 1435 TCP_ADD_STATS(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ); 1436 TCP_ADD_STATS(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ); 1437 TCP_ADD_STATS(net, TCP_MIB_MAXCONN, -1); 1438 } 1439 1440 /* from STCP */ 1441 static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp) 1442 { 1443 tp->lost_skb_hint = NULL; 1444 } 1445 1446 static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp) 1447 { 1448 tcp_clear_retrans_hints_partial(tp); 1449 tp->retransmit_skb_hint = NULL; 1450 } 1451 1452 union tcp_md5_addr { 1453 struct in_addr a4; 1454 #if IS_ENABLED(CONFIG_IPV6) 1455 struct in6_addr a6; 1456 #endif 1457 }; 1458 1459 /* - key database */ 1460 struct tcp_md5sig_key { 1461 struct hlist_node node; 1462 u8 keylen; 1463 u8 family; /* AF_INET or AF_INET6 */ 1464 union tcp_md5_addr addr; 1465 u8 prefixlen; 1466 u8 key[TCP_MD5SIG_MAXKEYLEN]; 1467 struct rcu_head rcu; 1468 }; 1469 1470 /* - sock block */ 1471 struct tcp_md5sig_info { 1472 struct hlist_head head; 1473 struct rcu_head rcu; 1474 }; 1475 1476 /* - pseudo header */ 1477 struct tcp4_pseudohdr { 1478 __be32 saddr; 1479 __be32 daddr; 1480 __u8 pad; 1481 __u8 protocol; 1482 __be16 len; 1483 }; 1484 1485 struct tcp6_pseudohdr { 1486 struct in6_addr saddr; 1487 struct in6_addr daddr; 1488 __be32 len; 1489 __be32 protocol; /* including padding */ 1490 }; 1491 1492 union tcp_md5sum_block { 1493 struct tcp4_pseudohdr ip4; 1494 #if IS_ENABLED(CONFIG_IPV6) 1495 struct tcp6_pseudohdr ip6; 1496 #endif 1497 }; 1498 1499 /* - pool: digest algorithm, hash description and scratch buffer */ 1500 struct tcp_md5sig_pool { 1501 struct ahash_request *md5_req; 1502 void *scratch; 1503 }; 1504 1505 /* - functions */ 1506 int tcp_v4_md5_hash_skb(char *md5_hash, const struct tcp_md5sig_key *key, 1507 const struct sock *sk, const struct sk_buff *skb); 1508 int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr, 1509 int family, u8 prefixlen, const u8 *newkey, u8 newkeylen, 1510 gfp_t gfp); 1511 int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr, 1512 int family, u8 prefixlen); 1513 struct tcp_md5sig_key *tcp_v4_md5_lookup(const struct sock *sk, 1514 const struct sock *addr_sk); 1515 1516 #ifdef CONFIG_TCP_MD5SIG 1517 struct tcp_md5sig_key *tcp_md5_do_lookup(const struct sock *sk, 1518 const union tcp_md5_addr *addr, 1519 int family); 1520 #define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key) 1521 #else 1522 static inline struct tcp_md5sig_key *tcp_md5_do_lookup(const struct sock *sk, 1523 const union tcp_md5_addr *addr, 1524 int family) 1525 { 1526 return NULL; 1527 } 1528 #define tcp_twsk_md5_key(twsk) NULL 1529 #endif 1530 1531 bool tcp_alloc_md5sig_pool(void); 1532 1533 struct tcp_md5sig_pool *tcp_get_md5sig_pool(void); 1534 static inline void tcp_put_md5sig_pool(void) 1535 { 1536 local_bh_enable(); 1537 } 1538 1539 int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *, 1540 unsigned int header_len); 1541 int tcp_md5_hash_key(struct tcp_md5sig_pool *hp, 1542 const struct tcp_md5sig_key *key); 1543 1544 /* From tcp_fastopen.c */ 1545 void tcp_fastopen_cache_get(struct sock *sk, u16 *mss, 1546 struct tcp_fastopen_cookie *cookie, int *syn_loss, 1547 unsigned long *last_syn_loss); 1548 void tcp_fastopen_cache_set(struct sock *sk, u16 mss, 1549 struct tcp_fastopen_cookie *cookie, bool syn_lost, 1550 u16 try_exp); 1551 struct tcp_fastopen_request { 1552 /* Fast Open cookie. Size 0 means a cookie request */ 1553 struct tcp_fastopen_cookie cookie; 1554 struct msghdr *data; /* data in MSG_FASTOPEN */ 1555 size_t size; 1556 int copied; /* queued in tcp_connect() */ 1557 }; 1558 void tcp_free_fastopen_req(struct tcp_sock *tp); 1559 1560 extern struct tcp_fastopen_context __rcu *tcp_fastopen_ctx; 1561 int tcp_fastopen_reset_cipher(void *key, unsigned int len); 1562 void tcp_fastopen_add_skb(struct sock *sk, struct sk_buff *skb); 1563 struct sock *tcp_try_fastopen(struct sock *sk, struct sk_buff *skb, 1564 struct request_sock *req, 1565 struct tcp_fastopen_cookie *foc); 1566 void tcp_fastopen_init_key_once(bool publish); 1567 bool tcp_fastopen_cookie_check(struct sock *sk, u16 *mss, 1568 struct tcp_fastopen_cookie *cookie); 1569 bool tcp_fastopen_defer_connect(struct sock *sk, int *err); 1570 #define TCP_FASTOPEN_KEY_LENGTH 16 1571 1572 /* Fastopen key context */ 1573 struct tcp_fastopen_context { 1574 struct crypto_cipher *tfm; 1575 __u8 key[TCP_FASTOPEN_KEY_LENGTH]; 1576 struct rcu_head rcu; 1577 }; 1578 1579 extern unsigned int sysctl_tcp_fastopen_blackhole_timeout; 1580 void tcp_fastopen_active_disable(struct sock *sk); 1581 bool tcp_fastopen_active_should_disable(struct sock *sk); 1582 void tcp_fastopen_active_disable_ofo_check(struct sock *sk); 1583 void tcp_fastopen_active_timeout_reset(void); 1584 1585 /* Latencies incurred by various limits for a sender. They are 1586 * chronograph-like stats that are mutually exclusive. 1587 */ 1588 enum tcp_chrono { 1589 TCP_CHRONO_UNSPEC, 1590 TCP_CHRONO_BUSY, /* Actively sending data (non-empty write queue) */ 1591 TCP_CHRONO_RWND_LIMITED, /* Stalled by insufficient receive window */ 1592 TCP_CHRONO_SNDBUF_LIMITED, /* Stalled by insufficient send buffer */ 1593 __TCP_CHRONO_MAX, 1594 }; 1595 1596 void tcp_chrono_start(struct sock *sk, const enum tcp_chrono type); 1597 void tcp_chrono_stop(struct sock *sk, const enum tcp_chrono type); 1598 1599 /* write queue abstraction */ 1600 static inline void tcp_write_queue_purge(struct sock *sk) 1601 { 1602 struct sk_buff *skb; 1603 1604 tcp_chrono_stop(sk, TCP_CHRONO_BUSY); 1605 while ((skb = __skb_dequeue(&sk->sk_write_queue)) != NULL) 1606 sk_wmem_free_skb(sk, skb); 1607 sk_mem_reclaim(sk); 1608 tcp_clear_all_retrans_hints(tcp_sk(sk)); 1609 } 1610 1611 static inline struct sk_buff *tcp_write_queue_head(const struct sock *sk) 1612 { 1613 return skb_peek(&sk->sk_write_queue); 1614 } 1615 1616 static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk) 1617 { 1618 return skb_peek_tail(&sk->sk_write_queue); 1619 } 1620 1621 static inline struct sk_buff *tcp_write_queue_next(const struct sock *sk, 1622 const struct sk_buff *skb) 1623 { 1624 return skb_queue_next(&sk->sk_write_queue, skb); 1625 } 1626 1627 static inline struct sk_buff *tcp_write_queue_prev(const struct sock *sk, 1628 const struct sk_buff *skb) 1629 { 1630 return skb_queue_prev(&sk->sk_write_queue, skb); 1631 } 1632 1633 #define tcp_for_write_queue(skb, sk) \ 1634 skb_queue_walk(&(sk)->sk_write_queue, skb) 1635 1636 #define tcp_for_write_queue_from(skb, sk) \ 1637 skb_queue_walk_from(&(sk)->sk_write_queue, skb) 1638 1639 #define tcp_for_write_queue_from_safe(skb, tmp, sk) \ 1640 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp) 1641 1642 static inline struct sk_buff *tcp_send_head(const struct sock *sk) 1643 { 1644 return sk->sk_send_head; 1645 } 1646 1647 static inline bool tcp_skb_is_last(const struct sock *sk, 1648 const struct sk_buff *skb) 1649 { 1650 return skb_queue_is_last(&sk->sk_write_queue, skb); 1651 } 1652 1653 static inline void tcp_advance_send_head(struct sock *sk, const struct sk_buff *skb) 1654 { 1655 if (tcp_skb_is_last(sk, skb)) 1656 sk->sk_send_head = NULL; 1657 else 1658 sk->sk_send_head = tcp_write_queue_next(sk, skb); 1659 } 1660 1661 static inline void tcp_check_send_head(struct sock *sk, struct sk_buff *skb_unlinked) 1662 { 1663 if (sk->sk_send_head == skb_unlinked) { 1664 sk->sk_send_head = NULL; 1665 tcp_chrono_stop(sk, TCP_CHRONO_BUSY); 1666 } 1667 if (tcp_sk(sk)->highest_sack == skb_unlinked) 1668 tcp_sk(sk)->highest_sack = NULL; 1669 } 1670 1671 static inline void tcp_init_send_head(struct sock *sk) 1672 { 1673 sk->sk_send_head = NULL; 1674 } 1675 1676 static inline void __tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb) 1677 { 1678 __skb_queue_tail(&sk->sk_write_queue, skb); 1679 } 1680 1681 static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb) 1682 { 1683 __tcp_add_write_queue_tail(sk, skb); 1684 1685 /* Queue it, remembering where we must start sending. */ 1686 if (sk->sk_send_head == NULL) { 1687 sk->sk_send_head = skb; 1688 tcp_chrono_start(sk, TCP_CHRONO_BUSY); 1689 1690 if (tcp_sk(sk)->highest_sack == NULL) 1691 tcp_sk(sk)->highest_sack = skb; 1692 } 1693 } 1694 1695 static inline void __tcp_add_write_queue_head(struct sock *sk, struct sk_buff *skb) 1696 { 1697 __skb_queue_head(&sk->sk_write_queue, skb); 1698 } 1699 1700 /* Insert buff after skb on the write queue of sk. */ 1701 static inline void tcp_insert_write_queue_after(struct sk_buff *skb, 1702 struct sk_buff *buff, 1703 struct sock *sk) 1704 { 1705 __skb_queue_after(&sk->sk_write_queue, skb, buff); 1706 } 1707 1708 /* Insert new before skb on the write queue of sk. */ 1709 static inline void tcp_insert_write_queue_before(struct sk_buff *new, 1710 struct sk_buff *skb, 1711 struct sock *sk) 1712 { 1713 __skb_queue_before(&sk->sk_write_queue, skb, new); 1714 1715 if (sk->sk_send_head == skb) 1716 sk->sk_send_head = new; 1717 } 1718 1719 static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk) 1720 { 1721 __skb_unlink(skb, &sk->sk_write_queue); 1722 } 1723 1724 static inline bool tcp_write_queue_empty(struct sock *sk) 1725 { 1726 return skb_queue_empty(&sk->sk_write_queue); 1727 } 1728 1729 static inline void tcp_push_pending_frames(struct sock *sk) 1730 { 1731 if (tcp_send_head(sk)) { 1732 struct tcp_sock *tp = tcp_sk(sk); 1733 1734 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle); 1735 } 1736 } 1737 1738 /* Start sequence of the skb just after the highest skb with SACKed 1739 * bit, valid only if sacked_out > 0 or when the caller has ensured 1740 * validity by itself. 1741 */ 1742 static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp) 1743 { 1744 if (!tp->sacked_out) 1745 return tp->snd_una; 1746 1747 if (tp->highest_sack == NULL) 1748 return tp->snd_nxt; 1749 1750 return TCP_SKB_CB(tp->highest_sack)->seq; 1751 } 1752 1753 static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb) 1754 { 1755 tcp_sk(sk)->highest_sack = tcp_skb_is_last(sk, skb) ? NULL : 1756 tcp_write_queue_next(sk, skb); 1757 } 1758 1759 static inline struct sk_buff *tcp_highest_sack(struct sock *sk) 1760 { 1761 return tcp_sk(sk)->highest_sack; 1762 } 1763 1764 static inline void tcp_highest_sack_reset(struct sock *sk) 1765 { 1766 tcp_sk(sk)->highest_sack = tcp_write_queue_head(sk); 1767 } 1768 1769 /* Called when old skb is about to be deleted (to be combined with new skb) */ 1770 static inline void tcp_highest_sack_combine(struct sock *sk, 1771 struct sk_buff *old, 1772 struct sk_buff *new) 1773 { 1774 if (tcp_sk(sk)->sacked_out && (old == tcp_sk(sk)->highest_sack)) 1775 tcp_sk(sk)->highest_sack = new; 1776 } 1777 1778 /* This helper checks if socket has IP_TRANSPARENT set */ 1779 static inline bool inet_sk_transparent(const struct sock *sk) 1780 { 1781 switch (sk->sk_state) { 1782 case TCP_TIME_WAIT: 1783 return inet_twsk(sk)->tw_transparent; 1784 case TCP_NEW_SYN_RECV: 1785 return inet_rsk(inet_reqsk(sk))->no_srccheck; 1786 } 1787 return inet_sk(sk)->transparent; 1788 } 1789 1790 /* Determines whether this is a thin stream (which may suffer from 1791 * increased latency). Used to trigger latency-reducing mechanisms. 1792 */ 1793 static inline bool tcp_stream_is_thin(struct tcp_sock *tp) 1794 { 1795 return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp); 1796 } 1797 1798 /* /proc */ 1799 enum tcp_seq_states { 1800 TCP_SEQ_STATE_LISTENING, 1801 TCP_SEQ_STATE_ESTABLISHED, 1802 }; 1803 1804 int tcp_seq_open(struct inode *inode, struct file *file); 1805 1806 struct tcp_seq_afinfo { 1807 char *name; 1808 sa_family_t family; 1809 const struct file_operations *seq_fops; 1810 struct seq_operations seq_ops; 1811 }; 1812 1813 struct tcp_iter_state { 1814 struct seq_net_private p; 1815 sa_family_t family; 1816 enum tcp_seq_states state; 1817 struct sock *syn_wait_sk; 1818 int bucket, offset, sbucket, num; 1819 loff_t last_pos; 1820 }; 1821 1822 int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo); 1823 void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo); 1824 1825 extern struct request_sock_ops tcp_request_sock_ops; 1826 extern struct request_sock_ops tcp6_request_sock_ops; 1827 1828 void tcp_v4_destroy_sock(struct sock *sk); 1829 1830 struct sk_buff *tcp_gso_segment(struct sk_buff *skb, 1831 netdev_features_t features); 1832 struct sk_buff **tcp_gro_receive(struct sk_buff **head, struct sk_buff *skb); 1833 int tcp_gro_complete(struct sk_buff *skb); 1834 1835 void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr, __be32 daddr); 1836 1837 static inline u32 tcp_notsent_lowat(const struct tcp_sock *tp) 1838 { 1839 struct net *net = sock_net((struct sock *)tp); 1840 return tp->notsent_lowat ?: net->ipv4.sysctl_tcp_notsent_lowat; 1841 } 1842 1843 static inline bool tcp_stream_memory_free(const struct sock *sk) 1844 { 1845 const struct tcp_sock *tp = tcp_sk(sk); 1846 u32 notsent_bytes = tp->write_seq - tp->snd_nxt; 1847 1848 return notsent_bytes < tcp_notsent_lowat(tp); 1849 } 1850 1851 #ifdef CONFIG_PROC_FS 1852 int tcp4_proc_init(void); 1853 void tcp4_proc_exit(void); 1854 #endif 1855 1856 int tcp_rtx_synack(const struct sock *sk, struct request_sock *req); 1857 int tcp_conn_request(struct request_sock_ops *rsk_ops, 1858 const struct tcp_request_sock_ops *af_ops, 1859 struct sock *sk, struct sk_buff *skb); 1860 1861 /* TCP af-specific functions */ 1862 struct tcp_sock_af_ops { 1863 #ifdef CONFIG_TCP_MD5SIG 1864 struct tcp_md5sig_key *(*md5_lookup) (const struct sock *sk, 1865 const struct sock *addr_sk); 1866 int (*calc_md5_hash)(char *location, 1867 const struct tcp_md5sig_key *md5, 1868 const struct sock *sk, 1869 const struct sk_buff *skb); 1870 int (*md5_parse)(struct sock *sk, 1871 int optname, 1872 char __user *optval, 1873 int optlen); 1874 #endif 1875 }; 1876 1877 struct tcp_request_sock_ops { 1878 u16 mss_clamp; 1879 #ifdef CONFIG_TCP_MD5SIG 1880 struct tcp_md5sig_key *(*req_md5_lookup)(const struct sock *sk, 1881 const struct sock *addr_sk); 1882 int (*calc_md5_hash) (char *location, 1883 const struct tcp_md5sig_key *md5, 1884 const struct sock *sk, 1885 const struct sk_buff *skb); 1886 #endif 1887 void (*init_req)(struct request_sock *req, 1888 const struct sock *sk_listener, 1889 struct sk_buff *skb); 1890 #ifdef CONFIG_SYN_COOKIES 1891 __u32 (*cookie_init_seq)(const struct sk_buff *skb, 1892 __u16 *mss); 1893 #endif 1894 struct dst_entry *(*route_req)(const struct sock *sk, struct flowi *fl, 1895 const struct request_sock *req); 1896 u32 (*init_seq)(const struct sk_buff *skb); 1897 u32 (*init_ts_off)(const struct net *net, const struct sk_buff *skb); 1898 int (*send_synack)(const struct sock *sk, struct dst_entry *dst, 1899 struct flowi *fl, struct request_sock *req, 1900 struct tcp_fastopen_cookie *foc, 1901 enum tcp_synack_type synack_type); 1902 }; 1903 1904 #ifdef CONFIG_SYN_COOKIES 1905 static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops, 1906 const struct sock *sk, struct sk_buff *skb, 1907 __u16 *mss) 1908 { 1909 tcp_synq_overflow(sk); 1910 __NET_INC_STATS(sock_net(sk), LINUX_MIB_SYNCOOKIESSENT); 1911 return ops->cookie_init_seq(skb, mss); 1912 } 1913 #else 1914 static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops, 1915 const struct sock *sk, struct sk_buff *skb, 1916 __u16 *mss) 1917 { 1918 return 0; 1919 } 1920 #endif 1921 1922 int tcpv4_offload_init(void); 1923 1924 void tcp_v4_init(void); 1925 void tcp_init(void); 1926 1927 /* tcp_recovery.c */ 1928 extern void tcp_rack_mark_lost(struct sock *sk); 1929 extern void tcp_rack_advance(struct tcp_sock *tp, u8 sacked, u32 end_seq, 1930 u64 xmit_time); 1931 extern void tcp_rack_reo_timeout(struct sock *sk); 1932 1933 /* At how many usecs into the future should the RTO fire? */ 1934 static inline s64 tcp_rto_delta_us(const struct sock *sk) 1935 { 1936 const struct sk_buff *skb = tcp_write_queue_head(sk); 1937 u32 rto = inet_csk(sk)->icsk_rto; 1938 u64 rto_time_stamp_us = skb->skb_mstamp + jiffies_to_usecs(rto); 1939 1940 return rto_time_stamp_us - tcp_sk(sk)->tcp_mstamp; 1941 } 1942 1943 /* 1944 * Save and compile IPv4 options, return a pointer to it 1945 */ 1946 static inline struct ip_options_rcu *tcp_v4_save_options(struct net *net, 1947 struct sk_buff *skb) 1948 { 1949 const struct ip_options *opt = &TCP_SKB_CB(skb)->header.h4.opt; 1950 struct ip_options_rcu *dopt = NULL; 1951 1952 if (opt->optlen) { 1953 int opt_size = sizeof(*dopt) + opt->optlen; 1954 1955 dopt = kmalloc(opt_size, GFP_ATOMIC); 1956 if (dopt && __ip_options_echo(net, &dopt->opt, skb, opt)) { 1957 kfree(dopt); 1958 dopt = NULL; 1959 } 1960 } 1961 return dopt; 1962 } 1963 1964 /* locally generated TCP pure ACKs have skb->truesize == 2 1965 * (check tcp_send_ack() in net/ipv4/tcp_output.c ) 1966 * This is much faster than dissecting the packet to find out. 1967 * (Think of GRE encapsulations, IPv4, IPv6, ...) 1968 */ 1969 static inline bool skb_is_tcp_pure_ack(const struct sk_buff *skb) 1970 { 1971 return skb->truesize == 2; 1972 } 1973 1974 static inline void skb_set_tcp_pure_ack(struct sk_buff *skb) 1975 { 1976 skb->truesize = 2; 1977 } 1978 1979 static inline int tcp_inq(struct sock *sk) 1980 { 1981 struct tcp_sock *tp = tcp_sk(sk); 1982 int answ; 1983 1984 if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) { 1985 answ = 0; 1986 } else if (sock_flag(sk, SOCK_URGINLINE) || 1987 !tp->urg_data || 1988 before(tp->urg_seq, tp->copied_seq) || 1989 !before(tp->urg_seq, tp->rcv_nxt)) { 1990 1991 answ = tp->rcv_nxt - tp->copied_seq; 1992 1993 /* Subtract 1, if FIN was received */ 1994 if (answ && sock_flag(sk, SOCK_DONE)) 1995 answ--; 1996 } else { 1997 answ = tp->urg_seq - tp->copied_seq; 1998 } 1999 2000 return answ; 2001 } 2002 2003 int tcp_peek_len(struct socket *sock); 2004 2005 static inline void tcp_segs_in(struct tcp_sock *tp, const struct sk_buff *skb) 2006 { 2007 u16 segs_in; 2008 2009 segs_in = max_t(u16, 1, skb_shinfo(skb)->gso_segs); 2010 tp->segs_in += segs_in; 2011 if (skb->len > tcp_hdrlen(skb)) 2012 tp->data_segs_in += segs_in; 2013 } 2014 2015 /* 2016 * TCP listen path runs lockless. 2017 * We forced "struct sock" to be const qualified to make sure 2018 * we don't modify one of its field by mistake. 2019 * Here, we increment sk_drops which is an atomic_t, so we can safely 2020 * make sock writable again. 2021 */ 2022 static inline void tcp_listendrop(const struct sock *sk) 2023 { 2024 atomic_inc(&((struct sock *)sk)->sk_drops); 2025 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS); 2026 } 2027 2028 enum hrtimer_restart tcp_pace_kick(struct hrtimer *timer); 2029 2030 /* 2031 * Interface for adding Upper Level Protocols over TCP 2032 */ 2033 2034 #define TCP_ULP_NAME_MAX 16 2035 #define TCP_ULP_MAX 128 2036 #define TCP_ULP_BUF_MAX (TCP_ULP_NAME_MAX*TCP_ULP_MAX) 2037 2038 struct tcp_ulp_ops { 2039 struct list_head list; 2040 2041 /* initialize ulp */ 2042 int (*init)(struct sock *sk); 2043 /* cleanup ulp */ 2044 void (*release)(struct sock *sk); 2045 2046 char name[TCP_ULP_NAME_MAX]; 2047 struct module *owner; 2048 }; 2049 int tcp_register_ulp(struct tcp_ulp_ops *type); 2050 void tcp_unregister_ulp(struct tcp_ulp_ops *type); 2051 int tcp_set_ulp(struct sock *sk, const char *name); 2052 void tcp_get_available_ulp(char *buf, size_t len); 2053 void tcp_cleanup_ulp(struct sock *sk); 2054 2055 /* Call BPF_SOCK_OPS program that returns an int. If the return value 2056 * is < 0, then the BPF op failed (for example if the loaded BPF 2057 * program does not support the chosen operation or there is no BPF 2058 * program loaded). 2059 */ 2060 #ifdef CONFIG_BPF 2061 static inline int tcp_call_bpf(struct sock *sk, int op) 2062 { 2063 struct bpf_sock_ops_kern sock_ops; 2064 int ret; 2065 2066 if (sk_fullsock(sk)) 2067 sock_owned_by_me(sk); 2068 2069 memset(&sock_ops, 0, sizeof(sock_ops)); 2070 sock_ops.sk = sk; 2071 sock_ops.op = op; 2072 2073 ret = BPF_CGROUP_RUN_PROG_SOCK_OPS(&sock_ops); 2074 if (ret == 0) 2075 ret = sock_ops.reply; 2076 else 2077 ret = -1; 2078 return ret; 2079 } 2080 #else 2081 static inline int tcp_call_bpf(struct sock *sk, int op) 2082 { 2083 return -EPERM; 2084 } 2085 #endif 2086 2087 static inline u32 tcp_timeout_init(struct sock *sk) 2088 { 2089 int timeout; 2090 2091 timeout = tcp_call_bpf(sk, BPF_SOCK_OPS_TIMEOUT_INIT); 2092 2093 if (timeout <= 0) 2094 timeout = TCP_TIMEOUT_INIT; 2095 return timeout; 2096 } 2097 2098 static inline u32 tcp_rwnd_init_bpf(struct sock *sk) 2099 { 2100 int rwnd; 2101 2102 rwnd = tcp_call_bpf(sk, BPF_SOCK_OPS_RWND_INIT); 2103 2104 if (rwnd < 0) 2105 rwnd = 0; 2106 return rwnd; 2107 } 2108 2109 static inline bool tcp_bpf_ca_needs_ecn(struct sock *sk) 2110 { 2111 return (tcp_call_bpf(sk, BPF_SOCK_OPS_NEEDS_ECN) == 1); 2112 } 2113 #endif /* _TCP_H */ 2114