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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/dmaengine.h>
31 #include <linux/crypto.h>
32 #include <linux/cryptohash.h>
33 #include <linux/kref.h>
34
35 #include <net/inet_connection_sock.h>
36 #include <net/inet_timewait_sock.h>
37 #include <net/inet_hashtables.h>
38 #include <net/checksum.h>
39 #include <net/request_sock.h>
40 #include <net/sock.h>
41 #include <net/snmp.h>
42 #include <net/ip.h>
43 #include <net/tcp_states.h>
44 #include <net/inet_ecn.h>
45 #include <net/dst.h>
46
47 #include <linux/seq_file.h>
48 #include <linux/memcontrol.h>
49
50 extern struct inet_hashinfo tcp_hashinfo;
51
52 extern struct percpu_counter tcp_orphan_count;
53 extern 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 /* Offer an initial receive window of 10 mss. */
65 #define TCP_DEFAULT_INIT_RCVWND 10
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 512
72
73 /* After receiving this amount of duplicate ACKs fast retransmit starts. */
74 #define TCP_FASTRETRANS_THRESH 3
75
76 /* Maximal reordering. */
77 #define TCP_MAX_REORDERING 127
78
79 /* Maximal number of ACKs sent quickly to accelerate slow-start. */
80 #define TCP_MAX_QUICKACKS 16U
81
82 /* urg_data states */
83 #define TCP_URG_VALID 0x0100
84 #define TCP_URG_NOTYET 0x0200
85 #define TCP_URG_READ 0x0400
86
87 #define TCP_RETR1 3 /*
88 * This is how many retries it does before it
89 * tries to figure out if the gateway is
90 * down. Minimal RFC value is 3; it corresponds
91 * to ~3sec-8min depending on RTO.
92 */
93
94 #define TCP_RETR2 15 /*
95 * This should take at least
96 * 90 minutes to time out.
97 * RFC1122 says that the limit is 100 sec.
98 * 15 is ~13-30min depending on RTO.
99 */
100
101 #define TCP_SYN_RETRIES 5 /* number of times to retry active opening a
102 * connection: ~180sec is RFC minimum */
103
104 #define TCP_SYNACK_RETRIES 5 /* number of times to retry passive opening a
105 * connection: ~180sec is RFC minimum */
106
107 #define TCP_TIMEWAIT_LEN (60*HZ) /* how long to wait to destroy TIME-WAIT
108 * state, about 60 seconds */
109 #define TCP_FIN_TIMEOUT TCP_TIMEWAIT_LEN
110 /* BSD style FIN_WAIT2 deadlock breaker.
111 * It used to be 3min, new value is 60sec,
112 * to combine FIN-WAIT-2 timeout with
113 * TIME-WAIT timer.
114 */
115
116 #define TCP_DELACK_MAX ((unsigned)(HZ/5)) /* maximal time to delay before sending an ACK */
117 #if HZ >= 100
118 #define TCP_DELACK_MIN ((unsigned)(HZ/25)) /* minimal time to delay before sending an ACK */
119 #define TCP_ATO_MIN ((unsigned)(HZ/25))
120 #else
121 #define TCP_DELACK_MIN 4U
122 #define TCP_ATO_MIN 4U
123 #endif
124 #define TCP_RTO_MAX ((unsigned)(120*HZ))
125 #define TCP_RTO_MIN ((unsigned)(HZ/5))
126 #define TCP_TIMEOUT_INIT ((unsigned)(1*HZ)) /* RFC6298 2.1 initial RTO value */
127 #define TCP_TIMEOUT_FALLBACK ((unsigned)(3*HZ)) /* RFC 1122 initial RTO value, now
128 * used as a fallback RTO for the
129 * initial data transmission if no
130 * valid RTT sample has been acquired,
131 * most likely due to retrans in 3WHS.
132 */
133
134 #define TCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ/2U)) /* Maximal interval between probes
135 * for local resources.
136 */
137
138 #define TCP_KEEPALIVE_TIME (120*60*HZ) /* two hours */
139 #define TCP_KEEPALIVE_PROBES 9 /* Max of 9 keepalive probes */
140 #define TCP_KEEPALIVE_INTVL (75*HZ)
141
142 #define MAX_TCP_KEEPIDLE 32767
143 #define MAX_TCP_KEEPINTVL 32767
144 #define MAX_TCP_KEEPCNT 127
145 #define MAX_TCP_SYNCNT 127
146
147 #define TCP_SYNQ_INTERVAL (HZ/5) /* Period of SYNACK timer */
148
149 #define TCP_PAWS_24DAYS (60 * 60 * 24 * 24)
150 #define TCP_PAWS_MSL 60 /* Per-host timestamps are invalidated
151 * after this time. It should be equal
152 * (or greater than) TCP_TIMEWAIT_LEN
153 * to provide reliability equal to one
154 * provided by timewait state.
155 */
156 #define TCP_PAWS_WINDOW 1 /* Replay window for per-host
157 * timestamps. It must be less than
158 * minimal timewait lifetime.
159 */
160 /*
161 * TCP option
162 */
163
164 #define TCPOPT_NOP 1 /* Padding */
165 #define TCPOPT_EOL 0 /* End of options */
166 #define TCPOPT_MSS 2 /* Segment size negotiating */
167 #define TCPOPT_WINDOW 3 /* Window scaling */
168 #define TCPOPT_SACK_PERM 4 /* SACK Permitted */
169 #define TCPOPT_SACK 5 /* SACK Block */
170 #define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */
171 #define TCPOPT_MD5SIG 19 /* MD5 Signature (RFC2385) */
172 #define TCPOPT_COOKIE 253 /* Cookie extension (experimental) */
173 #define TCPOPT_EXP 254 /* Experimental */
174 /* Magic number to be after the option value for sharing TCP
175 * experimental options. See draft-ietf-tcpm-experimental-options-00.txt
176 */
177 #define TCPOPT_FASTOPEN_MAGIC 0xF989
178
179 /*
180 * TCP option lengths
181 */
182
183 #define TCPOLEN_MSS 4
184 #define TCPOLEN_WINDOW 3
185 #define TCPOLEN_SACK_PERM 2
186 #define TCPOLEN_TIMESTAMP 10
187 #define TCPOLEN_MD5SIG 18
188 #define TCPOLEN_EXP_FASTOPEN_BASE 4
189 #define TCPOLEN_COOKIE_BASE 2 /* Cookie-less header extension */
190 #define TCPOLEN_COOKIE_PAIR 3 /* Cookie pair header extension */
191 #define TCPOLEN_COOKIE_MIN (TCPOLEN_COOKIE_BASE+TCP_COOKIE_MIN)
192 #define TCPOLEN_COOKIE_MAX (TCPOLEN_COOKIE_BASE+TCP_COOKIE_MAX)
193
194 /* But this is what stacks really send out. */
195 #define TCPOLEN_TSTAMP_ALIGNED 12
196 #define TCPOLEN_WSCALE_ALIGNED 4
197 #define TCPOLEN_SACKPERM_ALIGNED 4
198 #define TCPOLEN_SACK_BASE 2
199 #define TCPOLEN_SACK_BASE_ALIGNED 4
200 #define TCPOLEN_SACK_PERBLOCK 8
201 #define TCPOLEN_MD5SIG_ALIGNED 20
202 #define TCPOLEN_MSS_ALIGNED 4
203
204 /* Flags in tp->nonagle */
205 #define TCP_NAGLE_OFF 1 /* Nagle's algo is disabled */
206 #define TCP_NAGLE_CORK 2 /* Socket is corked */
207 #define TCP_NAGLE_PUSH 4 /* Cork is overridden for already queued data */
208
209 /* TCP thin-stream limits */
210 #define TCP_THIN_LINEAR_RETRIES 6 /* After 6 linear retries, do exp. backoff */
211
212 /* TCP initial congestion window as per draft-hkchu-tcpm-initcwnd-01 */
213 #define TCP_INIT_CWND 10
214
215 /* Bit Flags for sysctl_tcp_fastopen */
216 #define TFO_CLIENT_ENABLE 1
217 #define TFO_CLIENT_NO_COOKIE 4 /* Data in SYN w/o cookie option */
218
219 extern struct inet_timewait_death_row tcp_death_row;
220
221 /* sysctl variables for tcp */
222 extern int sysctl_tcp_timestamps;
223 extern int sysctl_tcp_window_scaling;
224 extern int sysctl_tcp_sack;
225 extern int sysctl_tcp_fin_timeout;
226 extern int sysctl_tcp_keepalive_time;
227 extern int sysctl_tcp_keepalive_probes;
228 extern int sysctl_tcp_keepalive_intvl;
229 extern int sysctl_tcp_syn_retries;
230 extern int sysctl_tcp_synack_retries;
231 extern int sysctl_tcp_retries1;
232 extern int sysctl_tcp_retries2;
233 extern int sysctl_tcp_orphan_retries;
234 extern int sysctl_tcp_syncookies;
235 extern int sysctl_tcp_fastopen;
236 extern int sysctl_tcp_retrans_collapse;
237 extern int sysctl_tcp_stdurg;
238 extern int sysctl_tcp_rfc1337;
239 extern int sysctl_tcp_abort_on_overflow;
240 extern int sysctl_tcp_max_orphans;
241 extern int sysctl_tcp_fack;
242 extern int sysctl_tcp_reordering;
243 extern int sysctl_tcp_ecn;
244 extern int sysctl_tcp_dsack;
245 extern int sysctl_tcp_wmem[3];
246 extern int sysctl_tcp_rmem[3];
247 extern int sysctl_tcp_app_win;
248 extern int sysctl_tcp_adv_win_scale;
249 extern int sysctl_tcp_tw_reuse;
250 extern int sysctl_tcp_frto;
251 extern int sysctl_tcp_frto_response;
252 extern int sysctl_tcp_low_latency;
253 extern int sysctl_tcp_dma_copybreak;
254 extern int sysctl_tcp_nometrics_save;
255 extern int sysctl_tcp_moderate_rcvbuf;
256 extern int sysctl_tcp_tso_win_divisor;
257 extern int sysctl_tcp_abc;
258 extern int sysctl_tcp_mtu_probing;
259 extern int sysctl_tcp_base_mss;
260 extern int sysctl_tcp_workaround_signed_windows;
261 extern int sysctl_tcp_slow_start_after_idle;
262 extern int sysctl_tcp_max_ssthresh;
263 extern int sysctl_tcp_cookie_size;
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_limit_output_bytes;
268 extern int sysctl_tcp_challenge_ack_limit;
269
270 extern atomic_long_t tcp_memory_allocated;
271 extern struct percpu_counter tcp_sockets_allocated;
272 extern int tcp_memory_pressure;
273
274 /*
275 * The next routines deal with comparing 32 bit unsigned ints
276 * and worry about wraparound (automatic with unsigned arithmetic).
277 */
278
279 static inline bool before(__u32 seq1, __u32 seq2)
280 {
281 return (__s32)(seq1-seq2) < 0;
282 }
283 #define after(seq2, seq1) before(seq1, seq2)
284
285 /* is s2<=s1<=s3 ? */
286 static inline bool between(__u32 seq1, __u32 seq2, __u32 seq3)
287 {
288 return seq3 - seq2 >= seq1 - seq2;
289 }
290
291 static inline bool tcp_out_of_memory(struct sock *sk)
292 {
293 if (sk->sk_wmem_queued > SOCK_MIN_SNDBUF &&
294 sk_memory_allocated(sk) > sk_prot_mem_limits(sk, 2))
295 return true;
296 return false;
297 }
298
299 static inline bool tcp_too_many_orphans(struct sock *sk, int shift)
300 {
301 struct percpu_counter *ocp = sk->sk_prot->orphan_count;
302 int orphans = percpu_counter_read_positive(ocp);
303
304 if (orphans << shift > sysctl_tcp_max_orphans) {
305 orphans = percpu_counter_sum_positive(ocp);
306 if (orphans << shift > sysctl_tcp_max_orphans)
307 return true;
308 }
309 return false;
310 }
311
312 extern bool tcp_check_oom(struct sock *sk, int shift);
313
314 /* syncookies: remember time of last synqueue overflow */
315 static inline void tcp_synq_overflow(struct sock *sk)
316 {
317 tcp_sk(sk)->rx_opt.ts_recent_stamp = jiffies;
318 }
319
320 /* syncookies: no recent synqueue overflow on this listening socket? */
321 static inline bool tcp_synq_no_recent_overflow(const struct sock *sk)
322 {
323 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp;
324 return time_after(jiffies, last_overflow + TCP_TIMEOUT_FALLBACK);
325 }
326
327 extern struct proto tcp_prot;
328
329 #define TCP_INC_STATS(net, field) SNMP_INC_STATS((net)->mib.tcp_statistics, field)
330 #define TCP_INC_STATS_BH(net, field) SNMP_INC_STATS_BH((net)->mib.tcp_statistics, field)
331 #define TCP_DEC_STATS(net, field) SNMP_DEC_STATS((net)->mib.tcp_statistics, field)
332 #define TCP_ADD_STATS_USER(net, field, val) SNMP_ADD_STATS_USER((net)->mib.tcp_statistics, field, val)
333 #define TCP_ADD_STATS(net, field, val) SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val)
334
335 extern void tcp_init_mem(struct net *net);
336
337 extern void tcp_tasklet_init(void);
338
339 extern void tcp_v4_err(struct sk_buff *skb, u32);
340
341 extern void tcp_shutdown (struct sock *sk, int how);
342
343 extern void tcp_v4_early_demux(struct sk_buff *skb);
344 extern int tcp_v4_rcv(struct sk_buff *skb);
345
346 extern struct inet_peer *tcp_v4_get_peer(struct sock *sk);
347 extern int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw);
348 extern int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
349 size_t size);
350 extern int tcp_sendpage(struct sock *sk, struct page *page, int offset,
351 size_t size, int flags);
352 extern void tcp_release_cb(struct sock *sk);
353 extern void tcp_write_timer_handler(struct sock *sk);
354 extern void tcp_delack_timer_handler(struct sock *sk);
355 extern int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg);
356 extern int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
357 const struct tcphdr *th, unsigned int len);
358 extern int tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
359 const struct tcphdr *th, unsigned int len);
360 extern void tcp_rcv_space_adjust(struct sock *sk);
361 extern void tcp_cleanup_rbuf(struct sock *sk, int copied);
362 extern int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp);
363 extern void tcp_twsk_destructor(struct sock *sk);
364 extern ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos,
365 struct pipe_inode_info *pipe, size_t len,
366 unsigned int flags);
367
368 static inline void tcp_dec_quickack_mode(struct sock *sk,
369 const unsigned int pkts)
370 {
371 struct inet_connection_sock *icsk = inet_csk(sk);
372
373 if (icsk->icsk_ack.quick) {
374 if (pkts >= icsk->icsk_ack.quick) {
375 icsk->icsk_ack.quick = 0;
376 /* Leaving quickack mode we deflate ATO. */
377 icsk->icsk_ack.ato = TCP_ATO_MIN;
378 } else
379 icsk->icsk_ack.quick -= pkts;
380 }
381 }
382
383 #define TCP_ECN_OK 1
384 #define TCP_ECN_QUEUE_CWR 2
385 #define TCP_ECN_DEMAND_CWR 4
386 #define TCP_ECN_SEEN 8
387
388 enum tcp_tw_status {
389 TCP_TW_SUCCESS = 0,
390 TCP_TW_RST = 1,
391 TCP_TW_ACK = 2,
392 TCP_TW_SYN = 3
393 };
394
395
396 extern enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw,
397 struct sk_buff *skb,
398 const struct tcphdr *th);
399 extern struct sock * tcp_check_req(struct sock *sk,struct sk_buff *skb,
400 struct request_sock *req,
401 struct request_sock **prev);
402 extern int tcp_child_process(struct sock *parent, struct sock *child,
403 struct sk_buff *skb);
404 extern bool tcp_use_frto(struct sock *sk);
405 extern void tcp_enter_frto(struct sock *sk);
406 extern void tcp_enter_loss(struct sock *sk, int how);
407 extern void tcp_clear_retrans(struct tcp_sock *tp);
408 extern void tcp_update_metrics(struct sock *sk);
409 extern void tcp_init_metrics(struct sock *sk);
410 extern void tcp_metrics_init(void);
411 extern bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst, bool paws_check);
412 extern bool tcp_remember_stamp(struct sock *sk);
413 extern bool tcp_tw_remember_stamp(struct inet_timewait_sock *tw);
414 extern void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
415 struct tcp_fastopen_cookie *cookie,
416 int *syn_loss, unsigned long *last_syn_loss);
417 extern void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
418 struct tcp_fastopen_cookie *cookie,
419 bool syn_lost);
420 extern void tcp_fetch_timewait_stamp(struct sock *sk, struct dst_entry *dst);
421 extern void tcp_disable_fack(struct tcp_sock *tp);
422 extern void tcp_close(struct sock *sk, long timeout);
423 extern void tcp_init_sock(struct sock *sk);
424 extern unsigned int tcp_poll(struct file * file, struct socket *sock,
425 struct poll_table_struct *wait);
426 extern int tcp_getsockopt(struct sock *sk, int level, int optname,
427 char __user *optval, int __user *optlen);
428 extern int tcp_setsockopt(struct sock *sk, int level, int optname,
429 char __user *optval, unsigned int optlen);
430 extern int compat_tcp_getsockopt(struct sock *sk, int level, int optname,
431 char __user *optval, int __user *optlen);
432 extern int compat_tcp_setsockopt(struct sock *sk, int level, int optname,
433 char __user *optval, unsigned int optlen);
434 extern void tcp_set_keepalive(struct sock *sk, int val);
435 extern void tcp_syn_ack_timeout(struct sock *sk, struct request_sock *req);
436 extern int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
437 size_t len, int nonblock, int flags, int *addr_len);
438 extern void tcp_parse_options(const struct sk_buff *skb,
439 struct tcp_options_received *opt_rx, const u8 **hvpp,
440 int estab, struct tcp_fastopen_cookie *foc);
441 extern const u8 *tcp_parse_md5sig_option(const struct tcphdr *th);
442
443 /*
444 * TCP v4 functions exported for the inet6 API
445 */
446
447 extern void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb);
448 extern int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb);
449 extern struct sock * tcp_create_openreq_child(struct sock *sk,
450 struct request_sock *req,
451 struct sk_buff *skb);
452 extern struct sock * tcp_v4_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
453 struct request_sock *req,
454 struct dst_entry *dst);
455 extern int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb);
456 extern int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr,
457 int addr_len);
458 extern int tcp_connect(struct sock *sk);
459 extern struct sk_buff * tcp_make_synack(struct sock *sk, struct dst_entry *dst,
460 struct request_sock *req,
461 struct request_values *rvp);
462 extern int tcp_disconnect(struct sock *sk, int flags);
463
464 void tcp_connect_init(struct sock *sk);
465 void tcp_finish_connect(struct sock *sk, struct sk_buff *skb);
466 int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size);
467 void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb);
468
469 /* From syncookies.c */
470 extern __u32 syncookie_secret[2][16-4+SHA_DIGEST_WORDS];
471 extern struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
472 struct ip_options *opt);
473 #ifdef CONFIG_SYN_COOKIES
474 extern __u32 cookie_v4_init_sequence(struct sock *sk, struct sk_buff *skb,
475 __u16 *mss);
476 #else
477 static inline __u32 cookie_v4_init_sequence(struct sock *sk,
478 struct sk_buff *skb,
479 __u16 *mss)
480 {
481 return 0;
482 }
483 #endif
484
485 extern __u32 cookie_init_timestamp(struct request_sock *req);
486 extern bool cookie_check_timestamp(struct tcp_options_received *opt, bool *);
487
488 /* From net/ipv6/syncookies.c */
489 extern struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb);
490 #ifdef CONFIG_SYN_COOKIES
491 extern __u32 cookie_v6_init_sequence(struct sock *sk, const struct sk_buff *skb,
492 __u16 *mss);
493 #else
494 static inline __u32 cookie_v6_init_sequence(struct sock *sk,
495 struct sk_buff *skb,
496 __u16 *mss)
497 {
498 return 0;
499 }
500 #endif
501 /* tcp_output.c */
502
503 extern void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss,
504 int nonagle);
505 extern bool tcp_may_send_now(struct sock *sk);
506 extern int tcp_retransmit_skb(struct sock *, struct sk_buff *);
507 extern void tcp_retransmit_timer(struct sock *sk);
508 extern void tcp_xmit_retransmit_queue(struct sock *);
509 extern void tcp_simple_retransmit(struct sock *);
510 extern int tcp_trim_head(struct sock *, struct sk_buff *, u32);
511 extern int tcp_fragment(struct sock *, struct sk_buff *, u32, unsigned int);
512
513 extern void tcp_send_probe0(struct sock *);
514 extern void tcp_send_partial(struct sock *);
515 extern int tcp_write_wakeup(struct sock *);
516 extern void tcp_send_fin(struct sock *sk);
517 extern void tcp_send_active_reset(struct sock *sk, gfp_t priority);
518 extern int tcp_send_synack(struct sock *);
519 extern bool tcp_syn_flood_action(struct sock *sk,
520 const struct sk_buff *skb,
521 const char *proto);
522 extern void tcp_push_one(struct sock *, unsigned int mss_now);
523 extern void tcp_send_ack(struct sock *sk);
524 extern void tcp_send_delayed_ack(struct sock *sk);
525
526 /* tcp_input.c */
527 extern void tcp_cwnd_application_limited(struct sock *sk);
528 extern void tcp_resume_early_retransmit(struct sock *sk);
529 extern void tcp_rearm_rto(struct sock *sk);
530
531 /* tcp_timer.c */
532 extern void tcp_init_xmit_timers(struct sock *);
533 static inline void tcp_clear_xmit_timers(struct sock *sk)
534 {
535 inet_csk_clear_xmit_timers(sk);
536 }
537
538 extern unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu);
539 extern unsigned int tcp_current_mss(struct sock *sk);
540
541 /* Bound MSS / TSO packet size with the half of the window */
542 static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize)
543 {
544 int cutoff;
545
546 /* When peer uses tiny windows, there is no use in packetizing
547 * to sub-MSS pieces for the sake of SWS or making sure there
548 * are enough packets in the pipe for fast recovery.
549 *
550 * On the other hand, for extremely large MSS devices, handling
551 * smaller than MSS windows in this way does make sense.
552 */
553 if (tp->max_window >= 512)
554 cutoff = (tp->max_window >> 1);
555 else
556 cutoff = tp->max_window;
557
558 if (cutoff && pktsize > cutoff)
559 return max_t(int, cutoff, 68U - tp->tcp_header_len);
560 else
561 return pktsize;
562 }
563
564 /* tcp.c */
565 extern void tcp_get_info(const struct sock *, struct tcp_info *);
566
567 /* Read 'sendfile()'-style from a TCP socket */
568 typedef int (*sk_read_actor_t)(read_descriptor_t *, struct sk_buff *,
569 unsigned int, size_t);
570 extern int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
571 sk_read_actor_t recv_actor);
572
573 extern void tcp_initialize_rcv_mss(struct sock *sk);
574
575 extern int tcp_mtu_to_mss(struct sock *sk, int pmtu);
576 extern int tcp_mss_to_mtu(struct sock *sk, int mss);
577 extern void tcp_mtup_init(struct sock *sk);
578 extern void tcp_valid_rtt_meas(struct sock *sk, u32 seq_rtt);
579
580 static inline void tcp_bound_rto(const struct sock *sk)
581 {
582 if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX)
583 inet_csk(sk)->icsk_rto = TCP_RTO_MAX;
584 }
585
586 static inline u32 __tcp_set_rto(const struct tcp_sock *tp)
587 {
588 return (tp->srtt >> 3) + tp->rttvar;
589 }
590
591 extern void tcp_set_rto(struct sock *sk);
592
593 static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd)
594 {
595 tp->pred_flags = htonl((tp->tcp_header_len << 26) |
596 ntohl(TCP_FLAG_ACK) |
597 snd_wnd);
598 }
599
600 static inline void tcp_fast_path_on(struct tcp_sock *tp)
601 {
602 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale);
603 }
604
605 static inline void tcp_fast_path_check(struct sock *sk)
606 {
607 struct tcp_sock *tp = tcp_sk(sk);
608
609 if (skb_queue_empty(&tp->out_of_order_queue) &&
610 tp->rcv_wnd &&
611 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf &&
612 !tp->urg_data)
613 tcp_fast_path_on(tp);
614 }
615
616 /* Compute the actual rto_min value */
617 static inline u32 tcp_rto_min(struct sock *sk)
618 {
619 const struct dst_entry *dst = __sk_dst_get(sk);
620 u32 rto_min = TCP_RTO_MIN;
621
622 if (dst && dst_metric_locked(dst, RTAX_RTO_MIN))
623 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN);
624 return rto_min;
625 }
626
627 /* Compute the actual receive window we are currently advertising.
628 * Rcv_nxt can be after the window if our peer push more data
629 * than the offered window.
630 */
631 static inline u32 tcp_receive_window(const struct tcp_sock *tp)
632 {
633 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt;
634
635 if (win < 0)
636 win = 0;
637 return (u32) win;
638 }
639
640 /* Choose a new window, without checks for shrinking, and without
641 * scaling applied to the result. The caller does these things
642 * if necessary. This is a "raw" window selection.
643 */
644 extern u32 __tcp_select_window(struct sock *sk);
645
646 void tcp_send_window_probe(struct sock *sk);
647
648 /* TCP timestamps are only 32-bits, this causes a slight
649 * complication on 64-bit systems since we store a snapshot
650 * of jiffies in the buffer control blocks below. We decided
651 * to use only the low 32-bits of jiffies and hide the ugly
652 * casts with the following macro.
653 */
654 #define tcp_time_stamp ((__u32)(jiffies))
655
656 #define tcp_flag_byte(th) (((u_int8_t *)th)[13])
657
658 #define TCPHDR_FIN 0x01
659 #define TCPHDR_SYN 0x02
660 #define TCPHDR_RST 0x04
661 #define TCPHDR_PSH 0x08
662 #define TCPHDR_ACK 0x10
663 #define TCPHDR_URG 0x20
664 #define TCPHDR_ECE 0x40
665 #define TCPHDR_CWR 0x80
666
667 /* This is what the send packet queuing engine uses to pass
668 * TCP per-packet control information to the transmission code.
669 * We also store the host-order sequence numbers in here too.
670 * This is 44 bytes if IPV6 is enabled.
671 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately.
672 */
673 struct tcp_skb_cb {
674 union {
675 struct inet_skb_parm h4;
676 #if IS_ENABLED(CONFIG_IPV6)
677 struct inet6_skb_parm h6;
678 #endif
679 } header; /* For incoming frames */
680 __u32 seq; /* Starting sequence number */
681 __u32 end_seq; /* SEQ + FIN + SYN + datalen */
682 __u32 when; /* used to compute rtt's */
683 __u8 tcp_flags; /* TCP header flags. (tcp[13]) */
684
685 __u8 sacked; /* State flags for SACK/FACK. */
686 #define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */
687 #define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */
688 #define TCPCB_LOST 0x04 /* SKB is lost */
689 #define TCPCB_TAGBITS 0x07 /* All tag bits */
690 #define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */
691 #define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS)
692
693 __u8 ip_dsfield; /* IPv4 tos or IPv6 dsfield */
694 /* 1 byte hole */
695 __u32 ack_seq; /* Sequence number ACK'd */
696 };
697
698 #define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0]))
699
700 /* RFC3168 : 6.1.1 SYN packets must not have ECT/ECN bits set
701 *
702 * If we receive a SYN packet with these bits set, it means a network is
703 * playing bad games with TOS bits. In order to avoid possible false congestion
704 * notifications, we disable TCP ECN negociation.
705 */
706 static inline void
707 TCP_ECN_create_request(struct request_sock *req, const struct sk_buff *skb)
708 {
709 const struct tcphdr *th = tcp_hdr(skb);
710
711 if (sysctl_tcp_ecn && th->ece && th->cwr &&
712 INET_ECN_is_not_ect(TCP_SKB_CB(skb)->ip_dsfield))
713 inet_rsk(req)->ecn_ok = 1;
714 }
715
716 /* Due to TSO, an SKB can be composed of multiple actual
717 * packets. To keep these tracked properly, we use this.
718 */
719 static inline int tcp_skb_pcount(const struct sk_buff *skb)
720 {
721 return skb_shinfo(skb)->gso_segs;
722 }
723
724 /* This is valid iff tcp_skb_pcount() > 1. */
725 static inline int tcp_skb_mss(const struct sk_buff *skb)
726 {
727 return skb_shinfo(skb)->gso_size;
728 }
729
730 /* Events passed to congestion control interface */
731 enum tcp_ca_event {
732 CA_EVENT_TX_START, /* first transmit when no packets in flight */
733 CA_EVENT_CWND_RESTART, /* congestion window restart */
734 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */
735 CA_EVENT_FRTO, /* fast recovery timeout */
736 CA_EVENT_LOSS, /* loss timeout */
737 CA_EVENT_FAST_ACK, /* in sequence ack */
738 CA_EVENT_SLOW_ACK, /* other ack */
739 };
740
741 /*
742 * Interface for adding new TCP congestion control handlers
743 */
744 #define TCP_CA_NAME_MAX 16
745 #define TCP_CA_MAX 128
746 #define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX)
747
748 #define TCP_CONG_NON_RESTRICTED 0x1
749 #define TCP_CONG_RTT_STAMP 0x2
750
751 struct tcp_congestion_ops {
752 struct list_head list;
753 unsigned long flags;
754
755 /* initialize private data (optional) */
756 void (*init)(struct sock *sk);
757 /* cleanup private data (optional) */
758 void (*release)(struct sock *sk);
759
760 /* return slow start threshold (required) */
761 u32 (*ssthresh)(struct sock *sk);
762 /* lower bound for congestion window (optional) */
763 u32 (*min_cwnd)(const struct sock *sk);
764 /* do new cwnd calculation (required) */
765 void (*cong_avoid)(struct sock *sk, u32 ack, u32 in_flight);
766 /* call before changing ca_state (optional) */
767 void (*set_state)(struct sock *sk, u8 new_state);
768 /* call when cwnd event occurs (optional) */
769 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev);
770 /* new value of cwnd after loss (optional) */
771 u32 (*undo_cwnd)(struct sock *sk);
772 /* hook for packet ack accounting (optional) */
773 void (*pkts_acked)(struct sock *sk, u32 num_acked, s32 rtt_us);
774 /* get info for inet_diag (optional) */
775 void (*get_info)(struct sock *sk, u32 ext, struct sk_buff *skb);
776
777 char name[TCP_CA_NAME_MAX];
778 struct module *owner;
779 };
780
781 extern int tcp_register_congestion_control(struct tcp_congestion_ops *type);
782 extern void tcp_unregister_congestion_control(struct tcp_congestion_ops *type);
783
784 extern void tcp_init_congestion_control(struct sock *sk);
785 extern void tcp_cleanup_congestion_control(struct sock *sk);
786 extern int tcp_set_default_congestion_control(const char *name);
787 extern void tcp_get_default_congestion_control(char *name);
788 extern void tcp_get_available_congestion_control(char *buf, size_t len);
789 extern void tcp_get_allowed_congestion_control(char *buf, size_t len);
790 extern int tcp_set_allowed_congestion_control(char *allowed);
791 extern int tcp_set_congestion_control(struct sock *sk, const char *name);
792 extern void tcp_slow_start(struct tcp_sock *tp);
793 extern void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w);
794
795 extern struct tcp_congestion_ops tcp_init_congestion_ops;
796 extern u32 tcp_reno_ssthresh(struct sock *sk);
797 extern void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 in_flight);
798 extern u32 tcp_reno_min_cwnd(const struct sock *sk);
799 extern struct tcp_congestion_ops tcp_reno;
800
801 static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state)
802 {
803 struct inet_connection_sock *icsk = inet_csk(sk);
804
805 if (icsk->icsk_ca_ops->set_state)
806 icsk->icsk_ca_ops->set_state(sk, ca_state);
807 icsk->icsk_ca_state = ca_state;
808 }
809
810 static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event)
811 {
812 const struct inet_connection_sock *icsk = inet_csk(sk);
813
814 if (icsk->icsk_ca_ops->cwnd_event)
815 icsk->icsk_ca_ops->cwnd_event(sk, event);
816 }
817
818 /* These functions determine how the current flow behaves in respect of SACK
819 * handling. SACK is negotiated with the peer, and therefore it can vary
820 * between different flows.
821 *
822 * tcp_is_sack - SACK enabled
823 * tcp_is_reno - No SACK
824 * tcp_is_fack - FACK enabled, implies SACK enabled
825 */
826 static inline int tcp_is_sack(const struct tcp_sock *tp)
827 {
828 return tp->rx_opt.sack_ok;
829 }
830
831 static inline bool tcp_is_reno(const struct tcp_sock *tp)
832 {
833 return !tcp_is_sack(tp);
834 }
835
836 static inline bool tcp_is_fack(const struct tcp_sock *tp)
837 {
838 return tp->rx_opt.sack_ok & TCP_FACK_ENABLED;
839 }
840
841 static inline void tcp_enable_fack(struct tcp_sock *tp)
842 {
843 tp->rx_opt.sack_ok |= TCP_FACK_ENABLED;
844 }
845
846 /* TCP early-retransmit (ER) is similar to but more conservative than
847 * the thin-dupack feature. Enable ER only if thin-dupack is disabled.
848 */
849 static inline void tcp_enable_early_retrans(struct tcp_sock *tp)
850 {
851 tp->do_early_retrans = sysctl_tcp_early_retrans &&
852 !sysctl_tcp_thin_dupack && sysctl_tcp_reordering == 3;
853 tp->early_retrans_delayed = 0;
854 }
855
856 static inline void tcp_disable_early_retrans(struct tcp_sock *tp)
857 {
858 tp->do_early_retrans = 0;
859 }
860
861 static inline unsigned int tcp_left_out(const struct tcp_sock *tp)
862 {
863 return tp->sacked_out + tp->lost_out;
864 }
865
866 /* This determines how many packets are "in the network" to the best
867 * of our knowledge. In many cases it is conservative, but where
868 * detailed information is available from the receiver (via SACK
869 * blocks etc.) we can make more aggressive calculations.
870 *
871 * Use this for decisions involving congestion control, use just
872 * tp->packets_out to determine if the send queue is empty or not.
873 *
874 * Read this equation as:
875 *
876 * "Packets sent once on transmission queue" MINUS
877 * "Packets left network, but not honestly ACKed yet" PLUS
878 * "Packets fast retransmitted"
879 */
880 static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp)
881 {
882 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out;
883 }
884
885 #define TCP_INFINITE_SSTHRESH 0x7fffffff
886
887 static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp)
888 {
889 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH;
890 }
891
892 /* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd.
893 * The exception is rate halving phase, when cwnd is decreasing towards
894 * ssthresh.
895 */
896 static inline __u32 tcp_current_ssthresh(const struct sock *sk)
897 {
898 const struct tcp_sock *tp = tcp_sk(sk);
899
900 if ((1 << inet_csk(sk)->icsk_ca_state) & (TCPF_CA_CWR | TCPF_CA_Recovery))
901 return tp->snd_ssthresh;
902 else
903 return max(tp->snd_ssthresh,
904 ((tp->snd_cwnd >> 1) +
905 (tp->snd_cwnd >> 2)));
906 }
907
908 /* Use define here intentionally to get WARN_ON location shown at the caller */
909 #define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out)
910
911 extern void tcp_enter_cwr(struct sock *sk, const int set_ssthresh);
912 extern __u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst);
913
914 /* The maximum number of MSS of available cwnd for which TSO defers
915 * sending if not using sysctl_tcp_tso_win_divisor.
916 */
917 static inline __u32 tcp_max_tso_deferred_mss(const struct tcp_sock *tp)
918 {
919 return 3;
920 }
921
922 /* Slow start with delack produces 3 packets of burst, so that
923 * it is safe "de facto". This will be the default - same as
924 * the default reordering threshold - but if reordering increases,
925 * we must be able to allow cwnd to burst at least this much in order
926 * to not pull it back when holes are filled.
927 */
928 static __inline__ __u32 tcp_max_burst(const struct tcp_sock *tp)
929 {
930 return tp->reordering;
931 }
932
933 /* Returns end sequence number of the receiver's advertised window */
934 static inline u32 tcp_wnd_end(const struct tcp_sock *tp)
935 {
936 return tp->snd_una + tp->snd_wnd;
937 }
938 extern bool tcp_is_cwnd_limited(const struct sock *sk, u32 in_flight);
939
940 static inline void tcp_minshall_update(struct tcp_sock *tp, unsigned int mss,
941 const struct sk_buff *skb)
942 {
943 if (skb->len < mss)
944 tp->snd_sml = TCP_SKB_CB(skb)->end_seq;
945 }
946
947 static inline void tcp_check_probe_timer(struct sock *sk)
948 {
949 const struct tcp_sock *tp = tcp_sk(sk);
950 const struct inet_connection_sock *icsk = inet_csk(sk);
951
952 if (!tp->packets_out && !icsk->icsk_pending)
953 inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
954 icsk->icsk_rto, TCP_RTO_MAX);
955 }
956
957 static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq)
958 {
959 tp->snd_wl1 = seq;
960 }
961
962 static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq)
963 {
964 tp->snd_wl1 = seq;
965 }
966
967 /*
968 * Calculate(/check) TCP checksum
969 */
970 static inline __sum16 tcp_v4_check(int len, __be32 saddr,
971 __be32 daddr, __wsum base)
972 {
973 return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base);
974 }
975
976 static inline __sum16 __tcp_checksum_complete(struct sk_buff *skb)
977 {
978 return __skb_checksum_complete(skb);
979 }
980
981 static inline bool tcp_checksum_complete(struct sk_buff *skb)
982 {
983 return !skb_csum_unnecessary(skb) &&
984 __tcp_checksum_complete(skb);
985 }
986
987 /* Prequeue for VJ style copy to user, combined with checksumming. */
988
989 static inline void tcp_prequeue_init(struct tcp_sock *tp)
990 {
991 tp->ucopy.task = NULL;
992 tp->ucopy.len = 0;
993 tp->ucopy.memory = 0;
994 skb_queue_head_init(&tp->ucopy.prequeue);
995 #ifdef CONFIG_NET_DMA
996 tp->ucopy.dma_chan = NULL;
997 tp->ucopy.wakeup = 0;
998 tp->ucopy.pinned_list = NULL;
999 tp->ucopy.dma_cookie = 0;
1000 #endif
1001 }
1002
1003 /* Packet is added to VJ-style prequeue for processing in process
1004 * context, if a reader task is waiting. Apparently, this exciting
1005 * idea (VJ's mail "Re: query about TCP header on tcp-ip" of 07 Sep 93)
1006 * failed somewhere. Latency? Burstiness? Well, at least now we will
1007 * see, why it failed. 8)8) --ANK
1008 *
1009 * NOTE: is this not too big to inline?
1010 */
1011 static inline bool tcp_prequeue(struct sock *sk, struct sk_buff *skb)
1012 {
1013 struct tcp_sock *tp = tcp_sk(sk);
1014
1015 if (sysctl_tcp_low_latency || !tp->ucopy.task)
1016 return false;
1017
1018 __skb_queue_tail(&tp->ucopy.prequeue, skb);
1019 tp->ucopy.memory += skb->truesize;
1020 if (tp->ucopy.memory > sk->sk_rcvbuf) {
1021 struct sk_buff *skb1;
1022
1023 BUG_ON(sock_owned_by_user(sk));
1024
1025 while ((skb1 = __skb_dequeue(&tp->ucopy.prequeue)) != NULL) {
1026 sk_backlog_rcv(sk, skb1);
1027 NET_INC_STATS_BH(sock_net(sk),
1028 LINUX_MIB_TCPPREQUEUEDROPPED);
1029 }
1030
1031 tp->ucopy.memory = 0;
1032 } else if (skb_queue_len(&tp->ucopy.prequeue) == 1) {
1033 wake_up_interruptible_sync_poll(sk_sleep(sk),
1034 POLLIN | POLLRDNORM | POLLRDBAND);
1035 if (!inet_csk_ack_scheduled(sk))
1036 inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
1037 (3 * tcp_rto_min(sk)) / 4,
1038 TCP_RTO_MAX);
1039 }
1040 return true;
1041 }
1042
1043
1044 #undef STATE_TRACE
1045
1046 #ifdef STATE_TRACE
1047 static const char *statename[]={
1048 "Unused","Established","Syn Sent","Syn Recv",
1049 "Fin Wait 1","Fin Wait 2","Time Wait", "Close",
1050 "Close Wait","Last ACK","Listen","Closing"
1051 };
1052 #endif
1053 extern void tcp_set_state(struct sock *sk, int state);
1054
1055 extern void tcp_done(struct sock *sk);
1056
1057 static inline void tcp_sack_reset(struct tcp_options_received *rx_opt)
1058 {
1059 rx_opt->dsack = 0;
1060 rx_opt->num_sacks = 0;
1061 }
1062
1063 /* Determine a window scaling and initial window to offer. */
1064 extern void tcp_select_initial_window(int __space, __u32 mss,
1065 __u32 *rcv_wnd, __u32 *window_clamp,
1066 int wscale_ok, __u8 *rcv_wscale,
1067 __u32 init_rcv_wnd);
1068
1069 static inline int tcp_win_from_space(int space)
1070 {
1071 return sysctl_tcp_adv_win_scale<=0 ?
1072 (space>>(-sysctl_tcp_adv_win_scale)) :
1073 space - (space>>sysctl_tcp_adv_win_scale);
1074 }
1075
1076 /* Note: caller must be prepared to deal with negative returns */
1077 static inline int tcp_space(const struct sock *sk)
1078 {
1079 return tcp_win_from_space(sk->sk_rcvbuf -
1080 atomic_read(&sk->sk_rmem_alloc));
1081 }
1082
1083 static inline int tcp_full_space(const struct sock *sk)
1084 {
1085 return tcp_win_from_space(sk->sk_rcvbuf);
1086 }
1087
1088 static inline void tcp_openreq_init(struct request_sock *req,
1089 struct tcp_options_received *rx_opt,
1090 struct sk_buff *skb)
1091 {
1092 struct inet_request_sock *ireq = inet_rsk(req);
1093
1094 req->rcv_wnd = 0; /* So that tcp_send_synack() knows! */
1095 req->cookie_ts = 0;
1096 tcp_rsk(req)->rcv_isn = TCP_SKB_CB(skb)->seq;
1097 req->mss = rx_opt->mss_clamp;
1098 req->ts_recent = rx_opt->saw_tstamp ? rx_opt->rcv_tsval : 0;
1099 ireq->tstamp_ok = rx_opt->tstamp_ok;
1100 ireq->sack_ok = rx_opt->sack_ok;
1101 ireq->snd_wscale = rx_opt->snd_wscale;
1102 ireq->wscale_ok = rx_opt->wscale_ok;
1103 ireq->acked = 0;
1104 ireq->ecn_ok = 0;
1105 ireq->rmt_port = tcp_hdr(skb)->source;
1106 ireq->loc_port = tcp_hdr(skb)->dest;
1107 }
1108
1109 extern void tcp_enter_memory_pressure(struct sock *sk);
1110
1111 static inline int keepalive_intvl_when(const struct tcp_sock *tp)
1112 {
1113 return tp->keepalive_intvl ? : sysctl_tcp_keepalive_intvl;
1114 }
1115
1116 static inline int keepalive_time_when(const struct tcp_sock *tp)
1117 {
1118 return tp->keepalive_time ? : sysctl_tcp_keepalive_time;
1119 }
1120
1121 static inline int keepalive_probes(const struct tcp_sock *tp)
1122 {
1123 return tp->keepalive_probes ? : sysctl_tcp_keepalive_probes;
1124 }
1125
1126 static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp)
1127 {
1128 const struct inet_connection_sock *icsk = &tp->inet_conn;
1129
1130 return min_t(u32, tcp_time_stamp - icsk->icsk_ack.lrcvtime,
1131 tcp_time_stamp - tp->rcv_tstamp);
1132 }
1133
1134 static inline int tcp_fin_time(const struct sock *sk)
1135 {
1136 int fin_timeout = tcp_sk(sk)->linger2 ? : sysctl_tcp_fin_timeout;
1137 const int rto = inet_csk(sk)->icsk_rto;
1138
1139 if (fin_timeout < (rto << 2) - (rto >> 1))
1140 fin_timeout = (rto << 2) - (rto >> 1);
1141
1142 return fin_timeout;
1143 }
1144
1145 static inline bool tcp_paws_check(const struct tcp_options_received *rx_opt,
1146 int paws_win)
1147 {
1148 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win)
1149 return true;
1150 if (unlikely(get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS))
1151 return true;
1152 /*
1153 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0,
1154 * then following tcp messages have valid values. Ignore 0 value,
1155 * or else 'negative' tsval might forbid us to accept their packets.
1156 */
1157 if (!rx_opt->ts_recent)
1158 return true;
1159 return false;
1160 }
1161
1162 static inline bool tcp_paws_reject(const struct tcp_options_received *rx_opt,
1163 int rst)
1164 {
1165 if (tcp_paws_check(rx_opt, 0))
1166 return false;
1167
1168 /* RST segments are not recommended to carry timestamp,
1169 and, if they do, it is recommended to ignore PAWS because
1170 "their cleanup function should take precedence over timestamps."
1171 Certainly, it is mistake. It is necessary to understand the reasons
1172 of this constraint to relax it: if peer reboots, clock may go
1173 out-of-sync and half-open connections will not be reset.
1174 Actually, the problem would be not existing if all
1175 the implementations followed draft about maintaining clock
1176 via reboots. Linux-2.2 DOES NOT!
1177
1178 However, we can relax time bounds for RST segments to MSL.
1179 */
1180 if (rst && get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_MSL)
1181 return false;
1182 return true;
1183 }
1184
1185 static inline void tcp_mib_init(struct net *net)
1186 {
1187 /* See RFC 2012 */
1188 TCP_ADD_STATS_USER(net, TCP_MIB_RTOALGORITHM, 1);
1189 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ);
1190 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ);
1191 TCP_ADD_STATS_USER(net, TCP_MIB_MAXCONN, -1);
1192 }
1193
1194 /* from STCP */
1195 static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp)
1196 {
1197 tp->lost_skb_hint = NULL;
1198 tp->scoreboard_skb_hint = NULL;
1199 }
1200
1201 static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp)
1202 {
1203 tcp_clear_retrans_hints_partial(tp);
1204 tp->retransmit_skb_hint = NULL;
1205 }
1206
1207 /* MD5 Signature */
1208 struct crypto_hash;
1209
1210 union tcp_md5_addr {
1211 struct in_addr a4;
1212 #if IS_ENABLED(CONFIG_IPV6)
1213 struct in6_addr a6;
1214 #endif
1215 };
1216
1217 /* - key database */
1218 struct tcp_md5sig_key {
1219 struct hlist_node node;
1220 u8 keylen;
1221 u8 family; /* AF_INET or AF_INET6 */
1222 union tcp_md5_addr addr;
1223 u8 key[TCP_MD5SIG_MAXKEYLEN];
1224 struct rcu_head rcu;
1225 };
1226
1227 /* - sock block */
1228 struct tcp_md5sig_info {
1229 struct hlist_head head;
1230 struct rcu_head rcu;
1231 };
1232
1233 /* - pseudo header */
1234 struct tcp4_pseudohdr {
1235 __be32 saddr;
1236 __be32 daddr;
1237 __u8 pad;
1238 __u8 protocol;
1239 __be16 len;
1240 };
1241
1242 struct tcp6_pseudohdr {
1243 struct in6_addr saddr;
1244 struct in6_addr daddr;
1245 __be32 len;
1246 __be32 protocol; /* including padding */
1247 };
1248
1249 union tcp_md5sum_block {
1250 struct tcp4_pseudohdr ip4;
1251 #if IS_ENABLED(CONFIG_IPV6)
1252 struct tcp6_pseudohdr ip6;
1253 #endif
1254 };
1255
1256 /* - pool: digest algorithm, hash description and scratch buffer */
1257 struct tcp_md5sig_pool {
1258 struct hash_desc md5_desc;
1259 union tcp_md5sum_block md5_blk;
1260 };
1261
1262 /* - functions */
1263 extern int tcp_v4_md5_hash_skb(char *md5_hash, struct tcp_md5sig_key *key,
1264 const struct sock *sk,
1265 const struct request_sock *req,
1266 const struct sk_buff *skb);
1267 extern int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
1268 int family, const u8 *newkey,
1269 u8 newkeylen, gfp_t gfp);
1270 extern int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr,
1271 int family);
1272 extern struct tcp_md5sig_key *tcp_v4_md5_lookup(struct sock *sk,
1273 struct sock *addr_sk);
1274
1275 #ifdef CONFIG_TCP_MD5SIG
1276 extern struct tcp_md5sig_key *tcp_md5_do_lookup(struct sock *sk,
1277 const union tcp_md5_addr *addr, int family);
1278 #define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key)
1279 #else
1280 static inline struct tcp_md5sig_key *tcp_md5_do_lookup(struct sock *sk,
1281 const union tcp_md5_addr *addr,
1282 int family)
1283 {
1284 return NULL;
1285 }
1286 #define tcp_twsk_md5_key(twsk) NULL
1287 #endif
1288
1289 extern struct tcp_md5sig_pool __percpu *tcp_alloc_md5sig_pool(struct sock *);
1290 extern void tcp_free_md5sig_pool(void);
1291
1292 extern struct tcp_md5sig_pool *tcp_get_md5sig_pool(void);
1293 extern void tcp_put_md5sig_pool(void);
1294
1295 extern int tcp_md5_hash_header(struct tcp_md5sig_pool *, const struct tcphdr *);
1296 extern int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *,
1297 unsigned int header_len);
1298 extern int tcp_md5_hash_key(struct tcp_md5sig_pool *hp,
1299 const struct tcp_md5sig_key *key);
1300
1301 struct tcp_fastopen_request {
1302 /* Fast Open cookie. Size 0 means a cookie request */
1303 struct tcp_fastopen_cookie cookie;
1304 struct msghdr *data; /* data in MSG_FASTOPEN */
1305 u16 copied; /* queued in tcp_connect() */
1306 };
1307
1308 void tcp_free_fastopen_req(struct tcp_sock *tp);
1309
1310 /* write queue abstraction */
1311 static inline void tcp_write_queue_purge(struct sock *sk)
1312 {
1313 struct sk_buff *skb;
1314
1315 while ((skb = __skb_dequeue(&sk->sk_write_queue)) != NULL)
1316 sk_wmem_free_skb(sk, skb);
1317 sk_mem_reclaim(sk);
1318 tcp_clear_all_retrans_hints(tcp_sk(sk));
1319 }
1320
1321 static inline struct sk_buff *tcp_write_queue_head(const struct sock *sk)
1322 {
1323 return skb_peek(&sk->sk_write_queue);
1324 }
1325
1326 static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk)
1327 {
1328 return skb_peek_tail(&sk->sk_write_queue);
1329 }
1330
1331 static inline struct sk_buff *tcp_write_queue_next(const struct sock *sk,
1332 const struct sk_buff *skb)
1333 {
1334 return skb_queue_next(&sk->sk_write_queue, skb);
1335 }
1336
1337 static inline struct sk_buff *tcp_write_queue_prev(const struct sock *sk,
1338 const struct sk_buff *skb)
1339 {
1340 return skb_queue_prev(&sk->sk_write_queue, skb);
1341 }
1342
1343 #define tcp_for_write_queue(skb, sk) \
1344 skb_queue_walk(&(sk)->sk_write_queue, skb)
1345
1346 #define tcp_for_write_queue_from(skb, sk) \
1347 skb_queue_walk_from(&(sk)->sk_write_queue, skb)
1348
1349 #define tcp_for_write_queue_from_safe(skb, tmp, sk) \
1350 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp)
1351
1352 static inline struct sk_buff *tcp_send_head(const struct sock *sk)
1353 {
1354 return sk->sk_send_head;
1355 }
1356
1357 static inline bool tcp_skb_is_last(const struct sock *sk,
1358 const struct sk_buff *skb)
1359 {
1360 return skb_queue_is_last(&sk->sk_write_queue, skb);
1361 }
1362
1363 static inline void tcp_advance_send_head(struct sock *sk, const struct sk_buff *skb)
1364 {
1365 if (tcp_skb_is_last(sk, skb))
1366 sk->sk_send_head = NULL;
1367 else
1368 sk->sk_send_head = tcp_write_queue_next(sk, skb);
1369 }
1370
1371 static inline void tcp_check_send_head(struct sock *sk, struct sk_buff *skb_unlinked)
1372 {
1373 if (sk->sk_send_head == skb_unlinked)
1374 sk->sk_send_head = NULL;
1375 }
1376
1377 static inline void tcp_init_send_head(struct sock *sk)
1378 {
1379 sk->sk_send_head = NULL;
1380 }
1381
1382 static inline void __tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1383 {
1384 __skb_queue_tail(&sk->sk_write_queue, skb);
1385 }
1386
1387 static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1388 {
1389 __tcp_add_write_queue_tail(sk, skb);
1390
1391 /* Queue it, remembering where we must start sending. */
1392 if (sk->sk_send_head == NULL) {
1393 sk->sk_send_head = skb;
1394
1395 if (tcp_sk(sk)->highest_sack == NULL)
1396 tcp_sk(sk)->highest_sack = skb;
1397 }
1398 }
1399
1400 static inline void __tcp_add_write_queue_head(struct sock *sk, struct sk_buff *skb)
1401 {
1402 __skb_queue_head(&sk->sk_write_queue, skb);
1403 }
1404
1405 /* Insert buff after skb on the write queue of sk. */
1406 static inline void tcp_insert_write_queue_after(struct sk_buff *skb,
1407 struct sk_buff *buff,
1408 struct sock *sk)
1409 {
1410 __skb_queue_after(&sk->sk_write_queue, skb, buff);
1411 }
1412
1413 /* Insert new before skb on the write queue of sk. */
1414 static inline void tcp_insert_write_queue_before(struct sk_buff *new,
1415 struct sk_buff *skb,
1416 struct sock *sk)
1417 {
1418 __skb_queue_before(&sk->sk_write_queue, skb, new);
1419
1420 if (sk->sk_send_head == skb)
1421 sk->sk_send_head = new;
1422 }
1423
1424 static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk)
1425 {
1426 __skb_unlink(skb, &sk->sk_write_queue);
1427 }
1428
1429 static inline bool tcp_write_queue_empty(struct sock *sk)
1430 {
1431 return skb_queue_empty(&sk->sk_write_queue);
1432 }
1433
1434 static inline void tcp_push_pending_frames(struct sock *sk)
1435 {
1436 if (tcp_send_head(sk)) {
1437 struct tcp_sock *tp = tcp_sk(sk);
1438
1439 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle);
1440 }
1441 }
1442
1443 /* Start sequence of the skb just after the highest skb with SACKed
1444 * bit, valid only if sacked_out > 0 or when the caller has ensured
1445 * validity by itself.
1446 */
1447 static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp)
1448 {
1449 if (!tp->sacked_out)
1450 return tp->snd_una;
1451
1452 if (tp->highest_sack == NULL)
1453 return tp->snd_nxt;
1454
1455 return TCP_SKB_CB(tp->highest_sack)->seq;
1456 }
1457
1458 static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb)
1459 {
1460 tcp_sk(sk)->highest_sack = tcp_skb_is_last(sk, skb) ? NULL :
1461 tcp_write_queue_next(sk, skb);
1462 }
1463
1464 static inline struct sk_buff *tcp_highest_sack(struct sock *sk)
1465 {
1466 return tcp_sk(sk)->highest_sack;
1467 }
1468
1469 static inline void tcp_highest_sack_reset(struct sock *sk)
1470 {
1471 tcp_sk(sk)->highest_sack = tcp_write_queue_head(sk);
1472 }
1473
1474 /* Called when old skb is about to be deleted (to be combined with new skb) */
1475 static inline void tcp_highest_sack_combine(struct sock *sk,
1476 struct sk_buff *old,
1477 struct sk_buff *new)
1478 {
1479 if (tcp_sk(sk)->sacked_out && (old == tcp_sk(sk)->highest_sack))
1480 tcp_sk(sk)->highest_sack = new;
1481 }
1482
1483 /* Determines whether this is a thin stream (which may suffer from
1484 * increased latency). Used to trigger latency-reducing mechanisms.
1485 */
1486 static inline bool tcp_stream_is_thin(struct tcp_sock *tp)
1487 {
1488 return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp);
1489 }
1490
1491 /* /proc */
1492 enum tcp_seq_states {
1493 TCP_SEQ_STATE_LISTENING,
1494 TCP_SEQ_STATE_OPENREQ,
1495 TCP_SEQ_STATE_ESTABLISHED,
1496 TCP_SEQ_STATE_TIME_WAIT,
1497 };
1498
1499 int tcp_seq_open(struct inode *inode, struct file *file);
1500
1501 struct tcp_seq_afinfo {
1502 char *name;
1503 sa_family_t family;
1504 const struct file_operations *seq_fops;
1505 struct seq_operations seq_ops;
1506 };
1507
1508 struct tcp_iter_state {
1509 struct seq_net_private p;
1510 sa_family_t family;
1511 enum tcp_seq_states state;
1512 struct sock *syn_wait_sk;
1513 int bucket, offset, sbucket, num;
1514 kuid_t uid;
1515 loff_t last_pos;
1516 };
1517
1518 extern int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo);
1519 extern void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo);
1520
1521 extern struct request_sock_ops tcp_request_sock_ops;
1522 extern struct request_sock_ops tcp6_request_sock_ops;
1523
1524 extern void tcp_v4_destroy_sock(struct sock *sk);
1525
1526 extern int tcp_v4_gso_send_check(struct sk_buff *skb);
1527 extern struct sk_buff *tcp_tso_segment(struct sk_buff *skb,
1528 netdev_features_t features);
1529 extern struct sk_buff **tcp_gro_receive(struct sk_buff **head,
1530 struct sk_buff *skb);
1531 extern struct sk_buff **tcp4_gro_receive(struct sk_buff **head,
1532 struct sk_buff *skb);
1533 extern int tcp_gro_complete(struct sk_buff *skb);
1534 extern int tcp4_gro_complete(struct sk_buff *skb);
1535
1536 #ifdef CONFIG_PROC_FS
1537 extern int tcp4_proc_init(void);
1538 extern void tcp4_proc_exit(void);
1539 #endif
1540
1541 /* TCP af-specific functions */
1542 struct tcp_sock_af_ops {
1543 #ifdef CONFIG_TCP_MD5SIG
1544 struct tcp_md5sig_key *(*md5_lookup) (struct sock *sk,
1545 struct sock *addr_sk);
1546 int (*calc_md5_hash) (char *location,
1547 struct tcp_md5sig_key *md5,
1548 const struct sock *sk,
1549 const struct request_sock *req,
1550 const struct sk_buff *skb);
1551 int (*md5_parse) (struct sock *sk,
1552 char __user *optval,
1553 int optlen);
1554 #endif
1555 };
1556
1557 struct tcp_request_sock_ops {
1558 #ifdef CONFIG_TCP_MD5SIG
1559 struct tcp_md5sig_key *(*md5_lookup) (struct sock *sk,
1560 struct request_sock *req);
1561 int (*calc_md5_hash) (char *location,
1562 struct tcp_md5sig_key *md5,
1563 const struct sock *sk,
1564 const struct request_sock *req,
1565 const struct sk_buff *skb);
1566 #endif
1567 };
1568
1569 /* Using SHA1 for now, define some constants.
1570 */
1571 #define COOKIE_DIGEST_WORDS (SHA_DIGEST_WORDS)
1572 #define COOKIE_MESSAGE_WORDS (SHA_MESSAGE_BYTES / 4)
1573 #define COOKIE_WORKSPACE_WORDS (COOKIE_DIGEST_WORDS + COOKIE_MESSAGE_WORDS)
1574
1575 extern int tcp_cookie_generator(u32 *bakery);
1576
1577 /**
1578 * struct tcp_cookie_values - each socket needs extra space for the
1579 * cookies, together with (optional) space for any SYN data.
1580 *
1581 * A tcp_sock contains a pointer to the current value, and this is
1582 * cloned to the tcp_timewait_sock.
1583 *
1584 * @cookie_pair: variable data from the option exchange.
1585 *
1586 * @cookie_desired: user specified tcpct_cookie_desired. Zero
1587 * indicates default (sysctl_tcp_cookie_size).
1588 * After cookie sent, remembers size of cookie.
1589 * Range 0, TCP_COOKIE_MIN to TCP_COOKIE_MAX.
1590 *
1591 * @s_data_desired: user specified tcpct_s_data_desired. When the
1592 * constant payload is specified (@s_data_constant),
1593 * holds its length instead.
1594 * Range 0 to TCP_MSS_DESIRED.
1595 *
1596 * @s_data_payload: constant data that is to be included in the
1597 * payload of SYN or SYNACK segments when the
1598 * cookie option is present.
1599 */
1600 struct tcp_cookie_values {
1601 struct kref kref;
1602 u8 cookie_pair[TCP_COOKIE_PAIR_SIZE];
1603 u8 cookie_pair_size;
1604 u8 cookie_desired;
1605 u16 s_data_desired:11,
1606 s_data_constant:1,
1607 s_data_in:1,
1608 s_data_out:1,
1609 s_data_unused:2;
1610 u8 s_data_payload[0];
1611 };
1612
1613 static inline void tcp_cookie_values_release(struct kref *kref)
1614 {
1615 kfree(container_of(kref, struct tcp_cookie_values, kref));
1616 }
1617
1618 /* The length of constant payload data. Note that s_data_desired is
1619 * overloaded, depending on s_data_constant: either the length of constant
1620 * data (returned here) or the limit on variable data.
1621 */
1622 static inline int tcp_s_data_size(const struct tcp_sock *tp)
1623 {
1624 return (tp->cookie_values != NULL && tp->cookie_values->s_data_constant)
1625 ? tp->cookie_values->s_data_desired
1626 : 0;
1627 }
1628
1629 /**
1630 * struct tcp_extend_values - tcp_ipv?.c to tcp_output.c workspace.
1631 *
1632 * As tcp_request_sock has already been extended in other places, the
1633 * only remaining method is to pass stack values along as function
1634 * parameters. These parameters are not needed after sending SYNACK.
1635 *
1636 * @cookie_bakery: cryptographic secret and message workspace.
1637 *
1638 * @cookie_plus: bytes in authenticator/cookie option, copied from
1639 * struct tcp_options_received (above).
1640 */
1641 struct tcp_extend_values {
1642 struct request_values rv;
1643 u32 cookie_bakery[COOKIE_WORKSPACE_WORDS];
1644 u8 cookie_plus:6,
1645 cookie_out_never:1,
1646 cookie_in_always:1;
1647 };
1648
1649 static inline struct tcp_extend_values *tcp_xv(struct request_values *rvp)
1650 {
1651 return (struct tcp_extend_values *)rvp;
1652 }
1653
1654 extern void tcp_v4_init(void);
1655 extern void tcp_init(void);
1656
1657 #endif /* _TCP_H */