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1/* SPDX-License-Identifier: GPL-2.0-or-later */
2/*
3 * INET An implementation of the TCP/IP protocol suite for the LINUX
4 * operating system. INET is implemented using the BSD Socket
5 * interface as the means of communication with the user level.
6 *
7 * Definitions for the TCP module.
8 *
9 * Version: @(#)tcp.h 1.0.5 05/23/93
10 *
11 * Authors: Ross Biro
12 * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
13 */
14#ifndef _TCP_H
15#define _TCP_H
16
17#define FASTRETRANS_DEBUG 1
18
19#include <linux/list.h>
20#include <linux/tcp.h>
21#include <linux/bug.h>
22#include <linux/slab.h>
23#include <linux/cache.h>
24#include <linux/percpu.h>
25#include <linux/skbuff.h>
26#include <linux/kref.h>
27#include <linux/ktime.h>
28#include <linux/indirect_call_wrapper.h>
29
30#include <net/inet_connection_sock.h>
31#include <net/inet_timewait_sock.h>
32#include <net/inet_hashtables.h>
33#include <net/checksum.h>
34#include <net/request_sock.h>
35#include <net/sock_reuseport.h>
36#include <net/sock.h>
37#include <net/snmp.h>
38#include <net/ip.h>
39#include <net/tcp_states.h>
40#include <net/tcp_ao.h>
41#include <net/inet_ecn.h>
42#include <net/dst.h>
43#include <net/mptcp.h>
44
45#include <linux/seq_file.h>
46#include <linux/memcontrol.h>
47#include <linux/bpf-cgroup.h>
48#include <linux/siphash.h>
49
50extern struct inet_hashinfo tcp_hashinfo;
51
52DECLARE_PER_CPU(unsigned int, tcp_orphan_count);
53int tcp_orphan_count_sum(void);
54
55void tcp_time_wait(struct sock *sk, int state, int timeo);
56
57#define MAX_TCP_HEADER L1_CACHE_ALIGN(128 + MAX_HEADER)
58#define MAX_TCP_OPTION_SPACE 40
59#define TCP_MIN_SND_MSS 48
60#define TCP_MIN_GSO_SIZE (TCP_MIN_SND_MSS - MAX_TCP_OPTION_SPACE)
61
62/*
63 * Never offer a window over 32767 without using window scaling. Some
64 * poor stacks do signed 16bit maths!
65 */
66#define MAX_TCP_WINDOW 32767U
67
68/* Minimal accepted MSS. It is (60+60+8) - (20+20). */
69#define TCP_MIN_MSS 88U
70
71/* The initial MTU to use for probing */
72#define TCP_BASE_MSS 1024
73
74/* probing interval, default to 10 minutes as per RFC4821 */
75#define TCP_PROBE_INTERVAL 600
76
77/* Specify interval when tcp mtu probing will stop */
78#define TCP_PROBE_THRESHOLD 8
79
80/* After receiving this amount of duplicate ACKs fast retransmit starts. */
81#define TCP_FASTRETRANS_THRESH 3
82
83/* Maximal number of ACKs sent quickly to accelerate slow-start. */
84#define TCP_MAX_QUICKACKS 16U
85
86/* Maximal number of window scale according to RFC1323 */
87#define TCP_MAX_WSCALE 14U
88
89/* urg_data states */
90#define TCP_URG_VALID 0x0100
91#define TCP_URG_NOTYET 0x0200
92#define TCP_URG_READ 0x0400
93
94#define TCP_RETR1 3 /*
95 * This is how many retries it does before it
96 * tries to figure out if the gateway is
97 * down. Minimal RFC value is 3; it corresponds
98 * to ~3sec-8min depending on RTO.
99 */
100
101#define TCP_RETR2 15 /*
102 * This should take at least
103 * 90 minutes to time out.
104 * RFC1122 says that the limit is 100 sec.
105 * 15 is ~13-30min depending on RTO.
106 */
107
108#define TCP_SYN_RETRIES 6 /* This is how many retries are done
109 * when active opening a connection.
110 * RFC1122 says the minimum retry MUST
111 * be at least 180secs. Nevertheless
112 * this value is corresponding to
113 * 63secs of retransmission with the
114 * current initial RTO.
115 */
116
117#define TCP_SYNACK_RETRIES 5 /* This is how may retries are done
118 * when passive opening a connection.
119 * This is corresponding to 31secs of
120 * retransmission with the current
121 * initial RTO.
122 */
123
124#define TCP_TIMEWAIT_LEN (60*HZ) /* how long to wait to destroy TIME-WAIT
125 * state, about 60 seconds */
126#define TCP_FIN_TIMEOUT TCP_TIMEWAIT_LEN
127 /* BSD style FIN_WAIT2 deadlock breaker.
128 * It used to be 3min, new value is 60sec,
129 * to combine FIN-WAIT-2 timeout with
130 * TIME-WAIT timer.
131 */
132#define TCP_FIN_TIMEOUT_MAX (120 * HZ) /* max TCP_LINGER2 value (two minutes) */
133
134#define TCP_DELACK_MAX ((unsigned)(HZ/5)) /* maximal time to delay before sending an ACK */
135static_assert((1 << ATO_BITS) > TCP_DELACK_MAX);
136
137#if HZ >= 100
138#define TCP_DELACK_MIN ((unsigned)(HZ/25)) /* minimal time to delay before sending an ACK */
139#define TCP_ATO_MIN ((unsigned)(HZ/25))
140#else
141#define TCP_DELACK_MIN 4U
142#define TCP_ATO_MIN 4U
143#endif
144#define TCP_RTO_MAX ((unsigned)(120*HZ))
145#define TCP_RTO_MIN ((unsigned)(HZ/5))
146#define TCP_TIMEOUT_MIN (2U) /* Min timeout for TCP timers in jiffies */
147
148#define TCP_TIMEOUT_MIN_US (2*USEC_PER_MSEC) /* Min TCP timeout in microsecs */
149
150#define TCP_TIMEOUT_INIT ((unsigned)(1*HZ)) /* RFC6298 2.1 initial RTO value */
151#define TCP_TIMEOUT_FALLBACK ((unsigned)(3*HZ)) /* RFC 1122 initial RTO value, now
152 * used as a fallback RTO for the
153 * initial data transmission if no
154 * valid RTT sample has been acquired,
155 * most likely due to retrans in 3WHS.
156 */
157
158#define TCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ/2U)) /* Maximal interval between probes
159 * for local resources.
160 */
161#define TCP_KEEPALIVE_TIME (120*60*HZ) /* two hours */
162#define TCP_KEEPALIVE_PROBES 9 /* Max of 9 keepalive probes */
163#define TCP_KEEPALIVE_INTVL (75*HZ)
164
165#define MAX_TCP_KEEPIDLE 32767
166#define MAX_TCP_KEEPINTVL 32767
167#define MAX_TCP_KEEPCNT 127
168#define MAX_TCP_SYNCNT 127
169
170/* Ensure that TCP PAWS checks are relaxed after ~2147 seconds
171 * to avoid overflows. This assumes a clock smaller than 1 Mhz.
172 * Default clock is 1 Khz, tcp_usec_ts uses 1 Mhz.
173 */
174#define TCP_PAWS_WRAP (INT_MAX / USEC_PER_SEC)
175
176#define TCP_PAWS_MSL 60 /* Per-host timestamps are invalidated
177 * after this time. It should be equal
178 * (or greater than) TCP_TIMEWAIT_LEN
179 * to provide reliability equal to one
180 * provided by timewait state.
181 */
182#define TCP_PAWS_WINDOW 1 /* Replay window for per-host
183 * timestamps. It must be less than
184 * minimal timewait lifetime.
185 */
186/*
187 * TCP option
188 */
189
190#define TCPOPT_NOP 1 /* Padding */
191#define TCPOPT_EOL 0 /* End of options */
192#define TCPOPT_MSS 2 /* Segment size negotiating */
193#define TCPOPT_WINDOW 3 /* Window scaling */
194#define TCPOPT_SACK_PERM 4 /* SACK Permitted */
195#define TCPOPT_SACK 5 /* SACK Block */
196#define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */
197#define TCPOPT_MD5SIG 19 /* MD5 Signature (RFC2385) */
198#define TCPOPT_AO 29 /* Authentication Option (RFC5925) */
199#define TCPOPT_MPTCP 30 /* Multipath TCP (RFC6824) */
200#define TCPOPT_FASTOPEN 34 /* Fast open (RFC7413) */
201#define TCPOPT_EXP 254 /* Experimental */
202/* Magic number to be after the option value for sharing TCP
203 * experimental options. See draft-ietf-tcpm-experimental-options-00.txt
204 */
205#define TCPOPT_FASTOPEN_MAGIC 0xF989
206#define TCPOPT_SMC_MAGIC 0xE2D4C3D9
207
208/*
209 * TCP option lengths
210 */
211
212#define TCPOLEN_MSS 4
213#define TCPOLEN_WINDOW 3
214#define TCPOLEN_SACK_PERM 2
215#define TCPOLEN_TIMESTAMP 10
216#define TCPOLEN_MD5SIG 18
217#define TCPOLEN_FASTOPEN_BASE 2
218#define TCPOLEN_EXP_FASTOPEN_BASE 4
219#define TCPOLEN_EXP_SMC_BASE 6
220
221/* But this is what stacks really send out. */
222#define TCPOLEN_TSTAMP_ALIGNED 12
223#define TCPOLEN_WSCALE_ALIGNED 4
224#define TCPOLEN_SACKPERM_ALIGNED 4
225#define TCPOLEN_SACK_BASE 2
226#define TCPOLEN_SACK_BASE_ALIGNED 4
227#define TCPOLEN_SACK_PERBLOCK 8
228#define TCPOLEN_MD5SIG_ALIGNED 20
229#define TCPOLEN_MSS_ALIGNED 4
230#define TCPOLEN_EXP_SMC_BASE_ALIGNED 8
231
232/* Flags in tp->nonagle */
233#define TCP_NAGLE_OFF 1 /* Nagle's algo is disabled */
234#define TCP_NAGLE_CORK 2 /* Socket is corked */
235#define TCP_NAGLE_PUSH 4 /* Cork is overridden for already queued data */
236
237/* TCP thin-stream limits */
238#define TCP_THIN_LINEAR_RETRIES 6 /* After 6 linear retries, do exp. backoff */
239
240/* TCP initial congestion window as per rfc6928 */
241#define TCP_INIT_CWND 10
242
243/* Bit Flags for sysctl_tcp_fastopen */
244#define TFO_CLIENT_ENABLE 1
245#define TFO_SERVER_ENABLE 2
246#define TFO_CLIENT_NO_COOKIE 4 /* Data in SYN w/o cookie option */
247
248/* Accept SYN data w/o any cookie option */
249#define TFO_SERVER_COOKIE_NOT_REQD 0x200
250
251/* Force enable TFO on all listeners, i.e., not requiring the
252 * TCP_FASTOPEN socket option.
253 */
254#define TFO_SERVER_WO_SOCKOPT1 0x400
255
256
257/* sysctl variables for tcp */
258extern int sysctl_tcp_max_orphans;
259extern long sysctl_tcp_mem[3];
260
261#define TCP_RACK_LOSS_DETECTION 0x1 /* Use RACK to detect losses */
262#define TCP_RACK_STATIC_REO_WND 0x2 /* Use static RACK reo wnd */
263#define TCP_RACK_NO_DUPTHRESH 0x4 /* Do not use DUPACK threshold in RACK */
264
265extern atomic_long_t tcp_memory_allocated;
266DECLARE_PER_CPU(int, tcp_memory_per_cpu_fw_alloc);
267
268extern struct percpu_counter tcp_sockets_allocated;
269extern unsigned long tcp_memory_pressure;
270
271/* optimized version of sk_under_memory_pressure() for TCP sockets */
272static inline bool tcp_under_memory_pressure(const struct sock *sk)
273{
274 if (mem_cgroup_sockets_enabled && sk->sk_memcg &&
275 mem_cgroup_under_socket_pressure(sk->sk_memcg))
276 return true;
277
278 return READ_ONCE(tcp_memory_pressure);
279}
280/*
281 * The next routines deal with comparing 32 bit unsigned ints
282 * and worry about wraparound (automatic with unsigned arithmetic).
283 */
284
285static inline bool before(__u32 seq1, __u32 seq2)
286{
287 return (__s32)(seq1-seq2) < 0;
288}
289#define after(seq2, seq1) before(seq1, seq2)
290
291/* is s2<=s1<=s3 ? */
292static inline bool between(__u32 seq1, __u32 seq2, __u32 seq3)
293{
294 return seq3 - seq2 >= seq1 - seq2;
295}
296
297static inline bool tcp_out_of_memory(struct sock *sk)
298{
299 if (sk->sk_wmem_queued > SOCK_MIN_SNDBUF &&
300 sk_memory_allocated(sk) > sk_prot_mem_limits(sk, 2))
301 return true;
302 return false;
303}
304
305static inline void tcp_wmem_free_skb(struct sock *sk, struct sk_buff *skb)
306{
307 sk_wmem_queued_add(sk, -skb->truesize);
308 if (!skb_zcopy_pure(skb))
309 sk_mem_uncharge(sk, skb->truesize);
310 else
311 sk_mem_uncharge(sk, SKB_TRUESIZE(skb_end_offset(skb)));
312 __kfree_skb(skb);
313}
314
315void sk_forced_mem_schedule(struct sock *sk, int size);
316
317bool tcp_check_oom(struct sock *sk, int shift);
318
319
320extern struct proto tcp_prot;
321
322#define TCP_INC_STATS(net, field) SNMP_INC_STATS((net)->mib.tcp_statistics, field)
323#define __TCP_INC_STATS(net, field) __SNMP_INC_STATS((net)->mib.tcp_statistics, field)
324#define TCP_DEC_STATS(net, field) SNMP_DEC_STATS((net)->mib.tcp_statistics, field)
325#define TCP_ADD_STATS(net, field, val) SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val)
326
327void tcp_tasklet_init(void);
328
329int tcp_v4_err(struct sk_buff *skb, u32);
330
331void tcp_shutdown(struct sock *sk, int how);
332
333int tcp_v4_early_demux(struct sk_buff *skb);
334int tcp_v4_rcv(struct sk_buff *skb);
335
336void tcp_remove_empty_skb(struct sock *sk);
337int tcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t size);
338int tcp_sendmsg_locked(struct sock *sk, struct msghdr *msg, size_t size);
339int tcp_sendmsg_fastopen(struct sock *sk, struct msghdr *msg, int *copied,
340 size_t size, struct ubuf_info *uarg);
341void tcp_splice_eof(struct socket *sock);
342int tcp_send_mss(struct sock *sk, int *size_goal, int flags);
343int tcp_wmem_schedule(struct sock *sk, int copy);
344void tcp_push(struct sock *sk, int flags, int mss_now, int nonagle,
345 int size_goal);
346void tcp_release_cb(struct sock *sk);
347void tcp_wfree(struct sk_buff *skb);
348void tcp_write_timer_handler(struct sock *sk);
349void tcp_delack_timer_handler(struct sock *sk);
350int tcp_ioctl(struct sock *sk, int cmd, int *karg);
351int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb);
352void tcp_rcv_established(struct sock *sk, struct sk_buff *skb);
353void tcp_rcv_space_adjust(struct sock *sk);
354int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp);
355void tcp_twsk_destructor(struct sock *sk);
356void tcp_twsk_purge(struct list_head *net_exit_list, int family);
357ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos,
358 struct pipe_inode_info *pipe, size_t len,
359 unsigned int flags);
360struct sk_buff *tcp_stream_alloc_skb(struct sock *sk, gfp_t gfp,
361 bool force_schedule);
362
363static inline void tcp_dec_quickack_mode(struct sock *sk)
364{
365 struct inet_connection_sock *icsk = inet_csk(sk);
366
367 if (icsk->icsk_ack.quick) {
368 /* How many ACKs S/ACKing new data have we sent? */
369 const unsigned int pkts = inet_csk_ack_scheduled(sk) ? 1 : 0;
370
371 if (pkts >= icsk->icsk_ack.quick) {
372 icsk->icsk_ack.quick = 0;
373 /* Leaving quickack mode we deflate ATO. */
374 icsk->icsk_ack.ato = TCP_ATO_MIN;
375 } else
376 icsk->icsk_ack.quick -= pkts;
377 }
378}
379
380#define TCP_ECN_OK 1
381#define TCP_ECN_QUEUE_CWR 2
382#define TCP_ECN_DEMAND_CWR 4
383#define TCP_ECN_SEEN 8
384
385enum tcp_tw_status {
386 TCP_TW_SUCCESS = 0,
387 TCP_TW_RST = 1,
388 TCP_TW_ACK = 2,
389 TCP_TW_SYN = 3
390};
391
392
393enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw,
394 struct sk_buff *skb,
395 const struct tcphdr *th);
396struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
397 struct request_sock *req, bool fastopen,
398 bool *lost_race);
399int tcp_child_process(struct sock *parent, struct sock *child,
400 struct sk_buff *skb);
401void tcp_enter_loss(struct sock *sk);
402void tcp_cwnd_reduction(struct sock *sk, int newly_acked_sacked, int newly_lost, int flag);
403void tcp_clear_retrans(struct tcp_sock *tp);
404void tcp_update_metrics(struct sock *sk);
405void tcp_init_metrics(struct sock *sk);
406void tcp_metrics_init(void);
407bool tcp_peer_is_proven(struct request_sock *req, struct dst_entry *dst);
408void __tcp_close(struct sock *sk, long timeout);
409void tcp_close(struct sock *sk, long timeout);
410void tcp_init_sock(struct sock *sk);
411void tcp_init_transfer(struct sock *sk, int bpf_op, struct sk_buff *skb);
412__poll_t tcp_poll(struct file *file, struct socket *sock,
413 struct poll_table_struct *wait);
414int do_tcp_getsockopt(struct sock *sk, int level,
415 int optname, sockptr_t optval, sockptr_t optlen);
416int tcp_getsockopt(struct sock *sk, int level, int optname,
417 char __user *optval, int __user *optlen);
418bool tcp_bpf_bypass_getsockopt(int level, int optname);
419int do_tcp_setsockopt(struct sock *sk, int level, int optname,
420 sockptr_t optval, unsigned int optlen);
421int tcp_setsockopt(struct sock *sk, int level, int optname, sockptr_t optval,
422 unsigned int optlen);
423void tcp_set_keepalive(struct sock *sk, int val);
424void tcp_syn_ack_timeout(const struct request_sock *req);
425int tcp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
426 int flags, int *addr_len);
427int tcp_set_rcvlowat(struct sock *sk, int val);
428int tcp_set_window_clamp(struct sock *sk, int val);
429void tcp_update_recv_tstamps(struct sk_buff *skb,
430 struct scm_timestamping_internal *tss);
431void tcp_recv_timestamp(struct msghdr *msg, const struct sock *sk,
432 struct scm_timestamping_internal *tss);
433void tcp_data_ready(struct sock *sk);
434#ifdef CONFIG_MMU
435int tcp_mmap(struct file *file, struct socket *sock,
436 struct vm_area_struct *vma);
437#endif
438void tcp_parse_options(const struct net *net, const struct sk_buff *skb,
439 struct tcp_options_received *opt_rx,
440 int estab, struct tcp_fastopen_cookie *foc);
441
442/*
443 * BPF SKB-less helpers
444 */
445u16 tcp_v4_get_syncookie(struct sock *sk, struct iphdr *iph,
446 struct tcphdr *th, u32 *cookie);
447u16 tcp_v6_get_syncookie(struct sock *sk, struct ipv6hdr *iph,
448 struct tcphdr *th, u32 *cookie);
449u16 tcp_parse_mss_option(const struct tcphdr *th, u16 user_mss);
450u16 tcp_get_syncookie_mss(struct request_sock_ops *rsk_ops,
451 const struct tcp_request_sock_ops *af_ops,
452 struct sock *sk, struct tcphdr *th);
453/*
454 * TCP v4 functions exported for the inet6 API
455 */
456
457void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb);
458void tcp_v4_mtu_reduced(struct sock *sk);
459void tcp_req_err(struct sock *sk, u32 seq, bool abort);
460void tcp_ld_RTO_revert(struct sock *sk, u32 seq);
461int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb);
462struct sock *tcp_create_openreq_child(const struct sock *sk,
463 struct request_sock *req,
464 struct sk_buff *skb);
465void tcp_ca_openreq_child(struct sock *sk, const struct dst_entry *dst);
466struct sock *tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb,
467 struct request_sock *req,
468 struct dst_entry *dst,
469 struct request_sock *req_unhash,
470 bool *own_req);
471int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb);
472int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len);
473int tcp_connect(struct sock *sk);
474enum tcp_synack_type {
475 TCP_SYNACK_NORMAL,
476 TCP_SYNACK_FASTOPEN,
477 TCP_SYNACK_COOKIE,
478};
479struct sk_buff *tcp_make_synack(const struct sock *sk, struct dst_entry *dst,
480 struct request_sock *req,
481 struct tcp_fastopen_cookie *foc,
482 enum tcp_synack_type synack_type,
483 struct sk_buff *syn_skb);
484int tcp_disconnect(struct sock *sk, int flags);
485
486void tcp_finish_connect(struct sock *sk, struct sk_buff *skb);
487int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size);
488void inet_sk_rx_dst_set(struct sock *sk, const struct sk_buff *skb);
489
490/* From syncookies.c */
491struct sock *tcp_get_cookie_sock(struct sock *sk, struct sk_buff *skb,
492 struct request_sock *req,
493 struct dst_entry *dst);
494int __cookie_v4_check(const struct iphdr *iph, const struct tcphdr *th);
495struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb);
496struct request_sock *cookie_tcp_reqsk_alloc(const struct request_sock_ops *ops,
497 struct sock *sk, struct sk_buff *skb,
498 struct tcp_options_received *tcp_opt,
499 int mss, u32 tsoff);
500
501#ifdef CONFIG_SYN_COOKIES
502
503/* Syncookies use a monotonic timer which increments every 60 seconds.
504 * This counter is used both as a hash input and partially encoded into
505 * the cookie value. A cookie is only validated further if the delta
506 * between the current counter value and the encoded one is less than this,
507 * i.e. a sent cookie is valid only at most for 2*60 seconds (or less if
508 * the counter advances immediately after a cookie is generated).
509 */
510#define MAX_SYNCOOKIE_AGE 2
511#define TCP_SYNCOOKIE_PERIOD (60 * HZ)
512#define TCP_SYNCOOKIE_VALID (MAX_SYNCOOKIE_AGE * TCP_SYNCOOKIE_PERIOD)
513
514/* syncookies: remember time of last synqueue overflow
515 * But do not dirty this field too often (once per second is enough)
516 * It is racy as we do not hold a lock, but race is very minor.
517 */
518static inline void tcp_synq_overflow(const struct sock *sk)
519{
520 unsigned int last_overflow;
521 unsigned int now = jiffies;
522
523 if (sk->sk_reuseport) {
524 struct sock_reuseport *reuse;
525
526 reuse = rcu_dereference(sk->sk_reuseport_cb);
527 if (likely(reuse)) {
528 last_overflow = READ_ONCE(reuse->synq_overflow_ts);
529 if (!time_between32(now, last_overflow,
530 last_overflow + HZ))
531 WRITE_ONCE(reuse->synq_overflow_ts, now);
532 return;
533 }
534 }
535
536 last_overflow = READ_ONCE(tcp_sk(sk)->rx_opt.ts_recent_stamp);
537 if (!time_between32(now, last_overflow, last_overflow + HZ))
538 WRITE_ONCE(tcp_sk_rw(sk)->rx_opt.ts_recent_stamp, now);
539}
540
541/* syncookies: no recent synqueue overflow on this listening socket? */
542static inline bool tcp_synq_no_recent_overflow(const struct sock *sk)
543{
544 unsigned int last_overflow;
545 unsigned int now = jiffies;
546
547 if (sk->sk_reuseport) {
548 struct sock_reuseport *reuse;
549
550 reuse = rcu_dereference(sk->sk_reuseport_cb);
551 if (likely(reuse)) {
552 last_overflow = READ_ONCE(reuse->synq_overflow_ts);
553 return !time_between32(now, last_overflow - HZ,
554 last_overflow +
555 TCP_SYNCOOKIE_VALID);
556 }
557 }
558
559 last_overflow = READ_ONCE(tcp_sk(sk)->rx_opt.ts_recent_stamp);
560
561 /* If last_overflow <= jiffies <= last_overflow + TCP_SYNCOOKIE_VALID,
562 * then we're under synflood. However, we have to use
563 * 'last_overflow - HZ' as lower bound. That's because a concurrent
564 * tcp_synq_overflow() could update .ts_recent_stamp after we read
565 * jiffies but before we store .ts_recent_stamp into last_overflow,
566 * which could lead to rejecting a valid syncookie.
567 */
568 return !time_between32(now, last_overflow - HZ,
569 last_overflow + TCP_SYNCOOKIE_VALID);
570}
571
572static inline u32 tcp_cookie_time(void)
573{
574 u64 val = get_jiffies_64();
575
576 do_div(val, TCP_SYNCOOKIE_PERIOD);
577 return val;
578}
579
580u32 __cookie_v4_init_sequence(const struct iphdr *iph, const struct tcphdr *th,
581 u16 *mssp);
582__u32 cookie_v4_init_sequence(const struct sk_buff *skb, __u16 *mss);
583u64 cookie_init_timestamp(struct request_sock *req, u64 now);
584bool cookie_timestamp_decode(const struct net *net,
585 struct tcp_options_received *opt);
586
587static inline bool cookie_ecn_ok(const struct net *net, const struct dst_entry *dst)
588{
589 return READ_ONCE(net->ipv4.sysctl_tcp_ecn) ||
590 dst_feature(dst, RTAX_FEATURE_ECN);
591}
592
593/* From net/ipv6/syncookies.c */
594int __cookie_v6_check(const struct ipv6hdr *iph, const struct tcphdr *th);
595struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb);
596
597u32 __cookie_v6_init_sequence(const struct ipv6hdr *iph,
598 const struct tcphdr *th, u16 *mssp);
599__u32 cookie_v6_init_sequence(const struct sk_buff *skb, __u16 *mss);
600#endif
601/* tcp_output.c */
602
603void tcp_skb_entail(struct sock *sk, struct sk_buff *skb);
604void tcp_mark_push(struct tcp_sock *tp, struct sk_buff *skb);
605void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss,
606 int nonagle);
607int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs);
608int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs);
609void tcp_retransmit_timer(struct sock *sk);
610void tcp_xmit_retransmit_queue(struct sock *);
611void tcp_simple_retransmit(struct sock *);
612void tcp_enter_recovery(struct sock *sk, bool ece_ack);
613int tcp_trim_head(struct sock *, struct sk_buff *, u32);
614enum tcp_queue {
615 TCP_FRAG_IN_WRITE_QUEUE,
616 TCP_FRAG_IN_RTX_QUEUE,
617};
618int tcp_fragment(struct sock *sk, enum tcp_queue tcp_queue,
619 struct sk_buff *skb, u32 len,
620 unsigned int mss_now, gfp_t gfp);
621
622void tcp_send_probe0(struct sock *);
623int tcp_write_wakeup(struct sock *, int mib);
624void tcp_send_fin(struct sock *sk);
625void tcp_send_active_reset(struct sock *sk, gfp_t priority);
626int tcp_send_synack(struct sock *);
627void tcp_push_one(struct sock *, unsigned int mss_now);
628void __tcp_send_ack(struct sock *sk, u32 rcv_nxt);
629void tcp_send_ack(struct sock *sk);
630void tcp_send_delayed_ack(struct sock *sk);
631void tcp_send_loss_probe(struct sock *sk);
632bool tcp_schedule_loss_probe(struct sock *sk, bool advancing_rto);
633void tcp_skb_collapse_tstamp(struct sk_buff *skb,
634 const struct sk_buff *next_skb);
635
636/* tcp_input.c */
637void tcp_rearm_rto(struct sock *sk);
638void tcp_synack_rtt_meas(struct sock *sk, struct request_sock *req);
639void tcp_reset(struct sock *sk, struct sk_buff *skb);
640void tcp_fin(struct sock *sk);
641void tcp_check_space(struct sock *sk);
642void tcp_sack_compress_send_ack(struct sock *sk);
643
644/* tcp_timer.c */
645void tcp_init_xmit_timers(struct sock *);
646static inline void tcp_clear_xmit_timers(struct sock *sk)
647{
648 if (hrtimer_try_to_cancel(&tcp_sk(sk)->pacing_timer) == 1)
649 __sock_put(sk);
650
651 if (hrtimer_try_to_cancel(&tcp_sk(sk)->compressed_ack_timer) == 1)
652 __sock_put(sk);
653
654 inet_csk_clear_xmit_timers(sk);
655}
656
657unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu);
658unsigned int tcp_current_mss(struct sock *sk);
659u32 tcp_clamp_probe0_to_user_timeout(const struct sock *sk, u32 when);
660
661/* Bound MSS / TSO packet size with the half of the window */
662static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize)
663{
664 int cutoff;
665
666 /* When peer uses tiny windows, there is no use in packetizing
667 * to sub-MSS pieces for the sake of SWS or making sure there
668 * are enough packets in the pipe for fast recovery.
669 *
670 * On the other hand, for extremely large MSS devices, handling
671 * smaller than MSS windows in this way does make sense.
672 */
673 if (tp->max_window > TCP_MSS_DEFAULT)
674 cutoff = (tp->max_window >> 1);
675 else
676 cutoff = tp->max_window;
677
678 if (cutoff && pktsize > cutoff)
679 return max_t(int, cutoff, 68U - tp->tcp_header_len);
680 else
681 return pktsize;
682}
683
684/* tcp.c */
685void tcp_get_info(struct sock *, struct tcp_info *);
686
687/* Read 'sendfile()'-style from a TCP socket */
688int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
689 sk_read_actor_t recv_actor);
690int tcp_read_skb(struct sock *sk, skb_read_actor_t recv_actor);
691struct sk_buff *tcp_recv_skb(struct sock *sk, u32 seq, u32 *off);
692void tcp_read_done(struct sock *sk, size_t len);
693
694void tcp_initialize_rcv_mss(struct sock *sk);
695
696int tcp_mtu_to_mss(struct sock *sk, int pmtu);
697int tcp_mss_to_mtu(struct sock *sk, int mss);
698void tcp_mtup_init(struct sock *sk);
699
700static inline void tcp_bound_rto(const struct sock *sk)
701{
702 if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX)
703 inet_csk(sk)->icsk_rto = TCP_RTO_MAX;
704}
705
706static inline u32 __tcp_set_rto(const struct tcp_sock *tp)
707{
708 return usecs_to_jiffies((tp->srtt_us >> 3) + tp->rttvar_us);
709}
710
711static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd)
712{
713 /* mptcp hooks are only on the slow path */
714 if (sk_is_mptcp((struct sock *)tp))
715 return;
716
717 tp->pred_flags = htonl((tp->tcp_header_len << 26) |
718 ntohl(TCP_FLAG_ACK) |
719 snd_wnd);
720}
721
722static inline void tcp_fast_path_on(struct tcp_sock *tp)
723{
724 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale);
725}
726
727static inline void tcp_fast_path_check(struct sock *sk)
728{
729 struct tcp_sock *tp = tcp_sk(sk);
730
731 if (RB_EMPTY_ROOT(&tp->out_of_order_queue) &&
732 tp->rcv_wnd &&
733 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf &&
734 !tp->urg_data)
735 tcp_fast_path_on(tp);
736}
737
738u32 tcp_delack_max(const struct sock *sk);
739
740/* Compute the actual rto_min value */
741static inline u32 tcp_rto_min(const struct sock *sk)
742{
743 const struct dst_entry *dst = __sk_dst_get(sk);
744 u32 rto_min = inet_csk(sk)->icsk_rto_min;
745
746 if (dst && dst_metric_locked(dst, RTAX_RTO_MIN))
747 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN);
748 return rto_min;
749}
750
751static inline u32 tcp_rto_min_us(const struct sock *sk)
752{
753 return jiffies_to_usecs(tcp_rto_min(sk));
754}
755
756static inline bool tcp_ca_dst_locked(const struct dst_entry *dst)
757{
758 return dst_metric_locked(dst, RTAX_CC_ALGO);
759}
760
761/* Minimum RTT in usec. ~0 means not available. */
762static inline u32 tcp_min_rtt(const struct tcp_sock *tp)
763{
764 return minmax_get(&tp->rtt_min);
765}
766
767/* Compute the actual receive window we are currently advertising.
768 * Rcv_nxt can be after the window if our peer push more data
769 * than the offered window.
770 */
771static inline u32 tcp_receive_window(const struct tcp_sock *tp)
772{
773 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt;
774
775 if (win < 0)
776 win = 0;
777 return (u32) win;
778}
779
780/* Choose a new window, without checks for shrinking, and without
781 * scaling applied to the result. The caller does these things
782 * if necessary. This is a "raw" window selection.
783 */
784u32 __tcp_select_window(struct sock *sk);
785
786void tcp_send_window_probe(struct sock *sk);
787
788/* TCP uses 32bit jiffies to save some space.
789 * Note that this is different from tcp_time_stamp, which
790 * historically has been the same until linux-4.13.
791 */
792#define tcp_jiffies32 ((u32)jiffies)
793
794/*
795 * Deliver a 32bit value for TCP timestamp option (RFC 7323)
796 * It is no longer tied to jiffies, but to 1 ms clock.
797 * Note: double check if you want to use tcp_jiffies32 instead of this.
798 */
799#define TCP_TS_HZ 1000
800
801static inline u64 tcp_clock_ns(void)
802{
803 return ktime_get_ns();
804}
805
806static inline u64 tcp_clock_us(void)
807{
808 return div_u64(tcp_clock_ns(), NSEC_PER_USEC);
809}
810
811static inline u64 tcp_clock_ms(void)
812{
813 return div_u64(tcp_clock_ns(), NSEC_PER_MSEC);
814}
815
816/* TCP Timestamp included in TS option (RFC 1323) can either use ms
817 * or usec resolution. Each socket carries a flag to select one or other
818 * resolution, as the route attribute could change anytime.
819 * Each flow must stick to initial resolution.
820 */
821static inline u32 tcp_clock_ts(bool usec_ts)
822{
823 return usec_ts ? tcp_clock_us() : tcp_clock_ms();
824}
825
826static inline u32 tcp_time_stamp_ms(const struct tcp_sock *tp)
827{
828 return div_u64(tp->tcp_mstamp, USEC_PER_MSEC);
829}
830
831static inline u32 tcp_time_stamp_ts(const struct tcp_sock *tp)
832{
833 if (tp->tcp_usec_ts)
834 return tp->tcp_mstamp;
835 return tcp_time_stamp_ms(tp);
836}
837
838void tcp_mstamp_refresh(struct tcp_sock *tp);
839
840static inline u32 tcp_stamp_us_delta(u64 t1, u64 t0)
841{
842 return max_t(s64, t1 - t0, 0);
843}
844
845/* provide the departure time in us unit */
846static inline u64 tcp_skb_timestamp_us(const struct sk_buff *skb)
847{
848 return div_u64(skb->skb_mstamp_ns, NSEC_PER_USEC);
849}
850
851/* Provide skb TSval in usec or ms unit */
852static inline u32 tcp_skb_timestamp_ts(bool usec_ts, const struct sk_buff *skb)
853{
854 if (usec_ts)
855 return tcp_skb_timestamp_us(skb);
856
857 return div_u64(skb->skb_mstamp_ns, NSEC_PER_MSEC);
858}
859
860static inline u32 tcp_tw_tsval(const struct tcp_timewait_sock *tcptw)
861{
862 return tcp_clock_ts(tcptw->tw_sk.tw_usec_ts) + tcptw->tw_ts_offset;
863}
864
865static inline u32 tcp_rsk_tsval(const struct tcp_request_sock *treq)
866{
867 return tcp_clock_ts(treq->req_usec_ts) + treq->ts_off;
868}
869
870#define tcp_flag_byte(th) (((u_int8_t *)th)[13])
871
872#define TCPHDR_FIN 0x01
873#define TCPHDR_SYN 0x02
874#define TCPHDR_RST 0x04
875#define TCPHDR_PSH 0x08
876#define TCPHDR_ACK 0x10
877#define TCPHDR_URG 0x20
878#define TCPHDR_ECE 0x40
879#define TCPHDR_CWR 0x80
880
881#define TCPHDR_SYN_ECN (TCPHDR_SYN | TCPHDR_ECE | TCPHDR_CWR)
882
883/* This is what the send packet queuing engine uses to pass
884 * TCP per-packet control information to the transmission code.
885 * We also store the host-order sequence numbers in here too.
886 * This is 44 bytes if IPV6 is enabled.
887 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately.
888 */
889struct tcp_skb_cb {
890 __u32 seq; /* Starting sequence number */
891 __u32 end_seq; /* SEQ + FIN + SYN + datalen */
892 union {
893 /* Note : tcp_tw_isn is used in input path only
894 * (isn chosen by tcp_timewait_state_process())
895 *
896 * tcp_gso_segs/size are used in write queue only,
897 * cf tcp_skb_pcount()/tcp_skb_mss()
898 */
899 __u32 tcp_tw_isn;
900 struct {
901 u16 tcp_gso_segs;
902 u16 tcp_gso_size;
903 };
904 };
905 __u8 tcp_flags; /* TCP header flags. (tcp[13]) */
906
907 __u8 sacked; /* State flags for SACK. */
908#define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */
909#define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */
910#define TCPCB_LOST 0x04 /* SKB is lost */
911#define TCPCB_TAGBITS 0x07 /* All tag bits */
912#define TCPCB_REPAIRED 0x10 /* SKB repaired (no skb_mstamp_ns) */
913#define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */
914#define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS| \
915 TCPCB_REPAIRED)
916
917 __u8 ip_dsfield; /* IPv4 tos or IPv6 dsfield */
918 __u8 txstamp_ack:1, /* Record TX timestamp for ack? */
919 eor:1, /* Is skb MSG_EOR marked? */
920 has_rxtstamp:1, /* SKB has a RX timestamp */
921 unused:5;
922 __u32 ack_seq; /* Sequence number ACK'd */
923 union {
924 struct {
925#define TCPCB_DELIVERED_CE_MASK ((1U<<20) - 1)
926 /* There is space for up to 24 bytes */
927 __u32 is_app_limited:1, /* cwnd not fully used? */
928 delivered_ce:20,
929 unused:11;
930 /* pkts S/ACKed so far upon tx of skb, incl retrans: */
931 __u32 delivered;
932 /* start of send pipeline phase */
933 u64 first_tx_mstamp;
934 /* when we reached the "delivered" count */
935 u64 delivered_mstamp;
936 } tx; /* only used for outgoing skbs */
937 union {
938 struct inet_skb_parm h4;
939#if IS_ENABLED(CONFIG_IPV6)
940 struct inet6_skb_parm h6;
941#endif
942 } header; /* For incoming skbs */
943 };
944};
945
946#define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0]))
947
948extern const struct inet_connection_sock_af_ops ipv4_specific;
949
950#if IS_ENABLED(CONFIG_IPV6)
951/* This is the variant of inet6_iif() that must be used by TCP,
952 * as TCP moves IP6CB into a different location in skb->cb[]
953 */
954static inline int tcp_v6_iif(const struct sk_buff *skb)
955{
956 return TCP_SKB_CB(skb)->header.h6.iif;
957}
958
959static inline int tcp_v6_iif_l3_slave(const struct sk_buff *skb)
960{
961 bool l3_slave = ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags);
962
963 return l3_slave ? skb->skb_iif : TCP_SKB_CB(skb)->header.h6.iif;
964}
965
966/* TCP_SKB_CB reference means this can not be used from early demux */
967static inline int tcp_v6_sdif(const struct sk_buff *skb)
968{
969#if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
970 if (skb && ipv6_l3mdev_skb(TCP_SKB_CB(skb)->header.h6.flags))
971 return TCP_SKB_CB(skb)->header.h6.iif;
972#endif
973 return 0;
974}
975
976extern const struct inet_connection_sock_af_ops ipv6_specific;
977
978INDIRECT_CALLABLE_DECLARE(void tcp_v6_send_check(struct sock *sk, struct sk_buff *skb));
979INDIRECT_CALLABLE_DECLARE(int tcp_v6_rcv(struct sk_buff *skb));
980void tcp_v6_early_demux(struct sk_buff *skb);
981
982#endif
983
984/* TCP_SKB_CB reference means this can not be used from early demux */
985static inline int tcp_v4_sdif(struct sk_buff *skb)
986{
987#if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
988 if (skb && ipv4_l3mdev_skb(TCP_SKB_CB(skb)->header.h4.flags))
989 return TCP_SKB_CB(skb)->header.h4.iif;
990#endif
991 return 0;
992}
993
994/* Due to TSO, an SKB can be composed of multiple actual
995 * packets. To keep these tracked properly, we use this.
996 */
997static inline int tcp_skb_pcount(const struct sk_buff *skb)
998{
999 return TCP_SKB_CB(skb)->tcp_gso_segs;
1000}
1001
1002static inline void tcp_skb_pcount_set(struct sk_buff *skb, int segs)
1003{
1004 TCP_SKB_CB(skb)->tcp_gso_segs = segs;
1005}
1006
1007static inline void tcp_skb_pcount_add(struct sk_buff *skb, int segs)
1008{
1009 TCP_SKB_CB(skb)->tcp_gso_segs += segs;
1010}
1011
1012/* This is valid iff skb is in write queue and tcp_skb_pcount() > 1. */
1013static inline int tcp_skb_mss(const struct sk_buff *skb)
1014{
1015 return TCP_SKB_CB(skb)->tcp_gso_size;
1016}
1017
1018static inline bool tcp_skb_can_collapse_to(const struct sk_buff *skb)
1019{
1020 return likely(!TCP_SKB_CB(skb)->eor);
1021}
1022
1023static inline bool tcp_skb_can_collapse(const struct sk_buff *to,
1024 const struct sk_buff *from)
1025{
1026 return likely(tcp_skb_can_collapse_to(to) &&
1027 mptcp_skb_can_collapse(to, from) &&
1028 skb_pure_zcopy_same(to, from));
1029}
1030
1031/* Events passed to congestion control interface */
1032enum tcp_ca_event {
1033 CA_EVENT_TX_START, /* first transmit when no packets in flight */
1034 CA_EVENT_CWND_RESTART, /* congestion window restart */
1035 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */
1036 CA_EVENT_LOSS, /* loss timeout */
1037 CA_EVENT_ECN_NO_CE, /* ECT set, but not CE marked */
1038 CA_EVENT_ECN_IS_CE, /* received CE marked IP packet */
1039};
1040
1041/* Information about inbound ACK, passed to cong_ops->in_ack_event() */
1042enum tcp_ca_ack_event_flags {
1043 CA_ACK_SLOWPATH = (1 << 0), /* In slow path processing */
1044 CA_ACK_WIN_UPDATE = (1 << 1), /* ACK updated window */
1045 CA_ACK_ECE = (1 << 2), /* ECE bit is set on ack */
1046};
1047
1048/*
1049 * Interface for adding new TCP congestion control handlers
1050 */
1051#define TCP_CA_NAME_MAX 16
1052#define TCP_CA_MAX 128
1053#define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX)
1054
1055#define TCP_CA_UNSPEC 0
1056
1057/* Algorithm can be set on socket without CAP_NET_ADMIN privileges */
1058#define TCP_CONG_NON_RESTRICTED 0x1
1059/* Requires ECN/ECT set on all packets */
1060#define TCP_CONG_NEEDS_ECN 0x2
1061#define TCP_CONG_MASK (TCP_CONG_NON_RESTRICTED | TCP_CONG_NEEDS_ECN)
1062
1063union tcp_cc_info;
1064
1065struct ack_sample {
1066 u32 pkts_acked;
1067 s32 rtt_us;
1068 u32 in_flight;
1069};
1070
1071/* A rate sample measures the number of (original/retransmitted) data
1072 * packets delivered "delivered" over an interval of time "interval_us".
1073 * The tcp_rate.c code fills in the rate sample, and congestion
1074 * control modules that define a cong_control function to run at the end
1075 * of ACK processing can optionally chose to consult this sample when
1076 * setting cwnd and pacing rate.
1077 * A sample is invalid if "delivered" or "interval_us" is negative.
1078 */
1079struct rate_sample {
1080 u64 prior_mstamp; /* starting timestamp for interval */
1081 u32 prior_delivered; /* tp->delivered at "prior_mstamp" */
1082 u32 prior_delivered_ce;/* tp->delivered_ce at "prior_mstamp" */
1083 s32 delivered; /* number of packets delivered over interval */
1084 s32 delivered_ce; /* number of packets delivered w/ CE marks*/
1085 long interval_us; /* time for tp->delivered to incr "delivered" */
1086 u32 snd_interval_us; /* snd interval for delivered packets */
1087 u32 rcv_interval_us; /* rcv interval for delivered packets */
1088 long rtt_us; /* RTT of last (S)ACKed packet (or -1) */
1089 int losses; /* number of packets marked lost upon ACK */
1090 u32 acked_sacked; /* number of packets newly (S)ACKed upon ACK */
1091 u32 prior_in_flight; /* in flight before this ACK */
1092 u32 last_end_seq; /* end_seq of most recently ACKed packet */
1093 bool is_app_limited; /* is sample from packet with bubble in pipe? */
1094 bool is_retrans; /* is sample from retransmission? */
1095 bool is_ack_delayed; /* is this (likely) a delayed ACK? */
1096};
1097
1098struct tcp_congestion_ops {
1099/* fast path fields are put first to fill one cache line */
1100
1101 /* return slow start threshold (required) */
1102 u32 (*ssthresh)(struct sock *sk);
1103
1104 /* do new cwnd calculation (required) */
1105 void (*cong_avoid)(struct sock *sk, u32 ack, u32 acked);
1106
1107 /* call before changing ca_state (optional) */
1108 void (*set_state)(struct sock *sk, u8 new_state);
1109
1110 /* call when cwnd event occurs (optional) */
1111 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev);
1112
1113 /* call when ack arrives (optional) */
1114 void (*in_ack_event)(struct sock *sk, u32 flags);
1115
1116 /* hook for packet ack accounting (optional) */
1117 void (*pkts_acked)(struct sock *sk, const struct ack_sample *sample);
1118
1119 /* override sysctl_tcp_min_tso_segs */
1120 u32 (*min_tso_segs)(struct sock *sk);
1121
1122 /* call when packets are delivered to update cwnd and pacing rate,
1123 * after all the ca_state processing. (optional)
1124 */
1125 void (*cong_control)(struct sock *sk, const struct rate_sample *rs);
1126
1127
1128 /* new value of cwnd after loss (required) */
1129 u32 (*undo_cwnd)(struct sock *sk);
1130 /* returns the multiplier used in tcp_sndbuf_expand (optional) */
1131 u32 (*sndbuf_expand)(struct sock *sk);
1132
1133/* control/slow paths put last */
1134 /* get info for inet_diag (optional) */
1135 size_t (*get_info)(struct sock *sk, u32 ext, int *attr,
1136 union tcp_cc_info *info);
1137
1138 char name[TCP_CA_NAME_MAX];
1139 struct module *owner;
1140 struct list_head list;
1141 u32 key;
1142 u32 flags;
1143
1144 /* initialize private data (optional) */
1145 void (*init)(struct sock *sk);
1146 /* cleanup private data (optional) */
1147 void (*release)(struct sock *sk);
1148} ____cacheline_aligned_in_smp;
1149
1150int tcp_register_congestion_control(struct tcp_congestion_ops *type);
1151void tcp_unregister_congestion_control(struct tcp_congestion_ops *type);
1152int tcp_update_congestion_control(struct tcp_congestion_ops *type,
1153 struct tcp_congestion_ops *old_type);
1154int tcp_validate_congestion_control(struct tcp_congestion_ops *ca);
1155
1156void tcp_assign_congestion_control(struct sock *sk);
1157void tcp_init_congestion_control(struct sock *sk);
1158void tcp_cleanup_congestion_control(struct sock *sk);
1159int tcp_set_default_congestion_control(struct net *net, const char *name);
1160void tcp_get_default_congestion_control(struct net *net, char *name);
1161void tcp_get_available_congestion_control(char *buf, size_t len);
1162void tcp_get_allowed_congestion_control(char *buf, size_t len);
1163int tcp_set_allowed_congestion_control(char *allowed);
1164int tcp_set_congestion_control(struct sock *sk, const char *name, bool load,
1165 bool cap_net_admin);
1166u32 tcp_slow_start(struct tcp_sock *tp, u32 acked);
1167void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w, u32 acked);
1168
1169u32 tcp_reno_ssthresh(struct sock *sk);
1170u32 tcp_reno_undo_cwnd(struct sock *sk);
1171void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 acked);
1172extern struct tcp_congestion_ops tcp_reno;
1173
1174struct tcp_congestion_ops *tcp_ca_find(const char *name);
1175struct tcp_congestion_ops *tcp_ca_find_key(u32 key);
1176u32 tcp_ca_get_key_by_name(struct net *net, const char *name, bool *ecn_ca);
1177#ifdef CONFIG_INET
1178char *tcp_ca_get_name_by_key(u32 key, char *buffer);
1179#else
1180static inline char *tcp_ca_get_name_by_key(u32 key, char *buffer)
1181{
1182 return NULL;
1183}
1184#endif
1185
1186static inline bool tcp_ca_needs_ecn(const struct sock *sk)
1187{
1188 const struct inet_connection_sock *icsk = inet_csk(sk);
1189
1190 return icsk->icsk_ca_ops->flags & TCP_CONG_NEEDS_ECN;
1191}
1192
1193static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event)
1194{
1195 const struct inet_connection_sock *icsk = inet_csk(sk);
1196
1197 if (icsk->icsk_ca_ops->cwnd_event)
1198 icsk->icsk_ca_ops->cwnd_event(sk, event);
1199}
1200
1201/* From tcp_cong.c */
1202void tcp_set_ca_state(struct sock *sk, const u8 ca_state);
1203
1204/* From tcp_rate.c */
1205void tcp_rate_skb_sent(struct sock *sk, struct sk_buff *skb);
1206void tcp_rate_skb_delivered(struct sock *sk, struct sk_buff *skb,
1207 struct rate_sample *rs);
1208void tcp_rate_gen(struct sock *sk, u32 delivered, u32 lost,
1209 bool is_sack_reneg, struct rate_sample *rs);
1210void tcp_rate_check_app_limited(struct sock *sk);
1211
1212static inline bool tcp_skb_sent_after(u64 t1, u64 t2, u32 seq1, u32 seq2)
1213{
1214 return t1 > t2 || (t1 == t2 && after(seq1, seq2));
1215}
1216
1217/* These functions determine how the current flow behaves in respect of SACK
1218 * handling. SACK is negotiated with the peer, and therefore it can vary
1219 * between different flows.
1220 *
1221 * tcp_is_sack - SACK enabled
1222 * tcp_is_reno - No SACK
1223 */
1224static inline int tcp_is_sack(const struct tcp_sock *tp)
1225{
1226 return likely(tp->rx_opt.sack_ok);
1227}
1228
1229static inline bool tcp_is_reno(const struct tcp_sock *tp)
1230{
1231 return !tcp_is_sack(tp);
1232}
1233
1234static inline unsigned int tcp_left_out(const struct tcp_sock *tp)
1235{
1236 return tp->sacked_out + tp->lost_out;
1237}
1238
1239/* This determines how many packets are "in the network" to the best
1240 * of our knowledge. In many cases it is conservative, but where
1241 * detailed information is available from the receiver (via SACK
1242 * blocks etc.) we can make more aggressive calculations.
1243 *
1244 * Use this for decisions involving congestion control, use just
1245 * tp->packets_out to determine if the send queue is empty or not.
1246 *
1247 * Read this equation as:
1248 *
1249 * "Packets sent once on transmission queue" MINUS
1250 * "Packets left network, but not honestly ACKed yet" PLUS
1251 * "Packets fast retransmitted"
1252 */
1253static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp)
1254{
1255 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out;
1256}
1257
1258#define TCP_INFINITE_SSTHRESH 0x7fffffff
1259
1260static inline u32 tcp_snd_cwnd(const struct tcp_sock *tp)
1261{
1262 return tp->snd_cwnd;
1263}
1264
1265static inline void tcp_snd_cwnd_set(struct tcp_sock *tp, u32 val)
1266{
1267 WARN_ON_ONCE((int)val <= 0);
1268 tp->snd_cwnd = val;
1269}
1270
1271static inline bool tcp_in_slow_start(const struct tcp_sock *tp)
1272{
1273 return tcp_snd_cwnd(tp) < tp->snd_ssthresh;
1274}
1275
1276static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp)
1277{
1278 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH;
1279}
1280
1281static inline bool tcp_in_cwnd_reduction(const struct sock *sk)
1282{
1283 return (TCPF_CA_CWR | TCPF_CA_Recovery) &
1284 (1 << inet_csk(sk)->icsk_ca_state);
1285}
1286
1287/* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd.
1288 * The exception is cwnd reduction phase, when cwnd is decreasing towards
1289 * ssthresh.
1290 */
1291static inline __u32 tcp_current_ssthresh(const struct sock *sk)
1292{
1293 const struct tcp_sock *tp = tcp_sk(sk);
1294
1295 if (tcp_in_cwnd_reduction(sk))
1296 return tp->snd_ssthresh;
1297 else
1298 return max(tp->snd_ssthresh,
1299 ((tcp_snd_cwnd(tp) >> 1) +
1300 (tcp_snd_cwnd(tp) >> 2)));
1301}
1302
1303/* Use define here intentionally to get WARN_ON location shown at the caller */
1304#define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out)
1305
1306void tcp_enter_cwr(struct sock *sk);
1307__u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst);
1308
1309/* The maximum number of MSS of available cwnd for which TSO defers
1310 * sending if not using sysctl_tcp_tso_win_divisor.
1311 */
1312static inline __u32 tcp_max_tso_deferred_mss(const struct tcp_sock *tp)
1313{
1314 return 3;
1315}
1316
1317/* Returns end sequence number of the receiver's advertised window */
1318static inline u32 tcp_wnd_end(const struct tcp_sock *tp)
1319{
1320 return tp->snd_una + tp->snd_wnd;
1321}
1322
1323/* We follow the spirit of RFC2861 to validate cwnd but implement a more
1324 * flexible approach. The RFC suggests cwnd should not be raised unless
1325 * it was fully used previously. And that's exactly what we do in
1326 * congestion avoidance mode. But in slow start we allow cwnd to grow
1327 * as long as the application has used half the cwnd.
1328 * Example :
1329 * cwnd is 10 (IW10), but application sends 9 frames.
1330 * We allow cwnd to reach 18 when all frames are ACKed.
1331 * This check is safe because it's as aggressive as slow start which already
1332 * risks 100% overshoot. The advantage is that we discourage application to
1333 * either send more filler packets or data to artificially blow up the cwnd
1334 * usage, and allow application-limited process to probe bw more aggressively.
1335 */
1336static inline bool tcp_is_cwnd_limited(const struct sock *sk)
1337{
1338 const struct tcp_sock *tp = tcp_sk(sk);
1339
1340 if (tp->is_cwnd_limited)
1341 return true;
1342
1343 /* If in slow start, ensure cwnd grows to twice what was ACKed. */
1344 if (tcp_in_slow_start(tp))
1345 return tcp_snd_cwnd(tp) < 2 * tp->max_packets_out;
1346
1347 return false;
1348}
1349
1350/* BBR congestion control needs pacing.
1351 * Same remark for SO_MAX_PACING_RATE.
1352 * sch_fq packet scheduler is efficiently handling pacing,
1353 * but is not always installed/used.
1354 * Return true if TCP stack should pace packets itself.
1355 */
1356static inline bool tcp_needs_internal_pacing(const struct sock *sk)
1357{
1358 return smp_load_acquire(&sk->sk_pacing_status) == SK_PACING_NEEDED;
1359}
1360
1361/* Estimates in how many jiffies next packet for this flow can be sent.
1362 * Scheduling a retransmit timer too early would be silly.
1363 */
1364static inline unsigned long tcp_pacing_delay(const struct sock *sk)
1365{
1366 s64 delay = tcp_sk(sk)->tcp_wstamp_ns - tcp_sk(sk)->tcp_clock_cache;
1367
1368 return delay > 0 ? nsecs_to_jiffies(delay) : 0;
1369}
1370
1371static inline void tcp_reset_xmit_timer(struct sock *sk,
1372 const int what,
1373 unsigned long when,
1374 const unsigned long max_when)
1375{
1376 inet_csk_reset_xmit_timer(sk, what, when + tcp_pacing_delay(sk),
1377 max_when);
1378}
1379
1380/* Something is really bad, we could not queue an additional packet,
1381 * because qdisc is full or receiver sent a 0 window, or we are paced.
1382 * We do not want to add fuel to the fire, or abort too early,
1383 * so make sure the timer we arm now is at least 200ms in the future,
1384 * regardless of current icsk_rto value (as it could be ~2ms)
1385 */
1386static inline unsigned long tcp_probe0_base(const struct sock *sk)
1387{
1388 return max_t(unsigned long, inet_csk(sk)->icsk_rto, TCP_RTO_MIN);
1389}
1390
1391/* Variant of inet_csk_rto_backoff() used for zero window probes */
1392static inline unsigned long tcp_probe0_when(const struct sock *sk,
1393 unsigned long max_when)
1394{
1395 u8 backoff = min_t(u8, ilog2(TCP_RTO_MAX / TCP_RTO_MIN) + 1,
1396 inet_csk(sk)->icsk_backoff);
1397 u64 when = (u64)tcp_probe0_base(sk) << backoff;
1398
1399 return (unsigned long)min_t(u64, when, max_when);
1400}
1401
1402static inline void tcp_check_probe_timer(struct sock *sk)
1403{
1404 if (!tcp_sk(sk)->packets_out && !inet_csk(sk)->icsk_pending)
1405 tcp_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
1406 tcp_probe0_base(sk), TCP_RTO_MAX);
1407}
1408
1409static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq)
1410{
1411 tp->snd_wl1 = seq;
1412}
1413
1414static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq)
1415{
1416 tp->snd_wl1 = seq;
1417}
1418
1419/*
1420 * Calculate(/check) TCP checksum
1421 */
1422static inline __sum16 tcp_v4_check(int len, __be32 saddr,
1423 __be32 daddr, __wsum base)
1424{
1425 return csum_tcpudp_magic(saddr, daddr, len, IPPROTO_TCP, base);
1426}
1427
1428static inline bool tcp_checksum_complete(struct sk_buff *skb)
1429{
1430 return !skb_csum_unnecessary(skb) &&
1431 __skb_checksum_complete(skb);
1432}
1433
1434bool tcp_add_backlog(struct sock *sk, struct sk_buff *skb,
1435 enum skb_drop_reason *reason);
1436
1437
1438int tcp_filter(struct sock *sk, struct sk_buff *skb);
1439void tcp_set_state(struct sock *sk, int state);
1440void tcp_done(struct sock *sk);
1441int tcp_abort(struct sock *sk, int err);
1442
1443static inline void tcp_sack_reset(struct tcp_options_received *rx_opt)
1444{
1445 rx_opt->dsack = 0;
1446 rx_opt->num_sacks = 0;
1447}
1448
1449void tcp_cwnd_restart(struct sock *sk, s32 delta);
1450
1451static inline void tcp_slow_start_after_idle_check(struct sock *sk)
1452{
1453 const struct tcp_congestion_ops *ca_ops = inet_csk(sk)->icsk_ca_ops;
1454 struct tcp_sock *tp = tcp_sk(sk);
1455 s32 delta;
1456
1457 if (!READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_slow_start_after_idle) ||
1458 tp->packets_out || ca_ops->cong_control)
1459 return;
1460 delta = tcp_jiffies32 - tp->lsndtime;
1461 if (delta > inet_csk(sk)->icsk_rto)
1462 tcp_cwnd_restart(sk, delta);
1463}
1464
1465/* Determine a window scaling and initial window to offer. */
1466void tcp_select_initial_window(const struct sock *sk, int __space,
1467 __u32 mss, __u32 *rcv_wnd,
1468 __u32 *window_clamp, int wscale_ok,
1469 __u8 *rcv_wscale, __u32 init_rcv_wnd);
1470
1471static inline int __tcp_win_from_space(u8 scaling_ratio, int space)
1472{
1473 s64 scaled_space = (s64)space * scaling_ratio;
1474
1475 return scaled_space >> TCP_RMEM_TO_WIN_SCALE;
1476}
1477
1478static inline int tcp_win_from_space(const struct sock *sk, int space)
1479{
1480 return __tcp_win_from_space(tcp_sk(sk)->scaling_ratio, space);
1481}
1482
1483/* inverse of __tcp_win_from_space() */
1484static inline int __tcp_space_from_win(u8 scaling_ratio, int win)
1485{
1486 u64 val = (u64)win << TCP_RMEM_TO_WIN_SCALE;
1487
1488 do_div(val, scaling_ratio);
1489 return val;
1490}
1491
1492static inline int tcp_space_from_win(const struct sock *sk, int win)
1493{
1494 return __tcp_space_from_win(tcp_sk(sk)->scaling_ratio, win);
1495}
1496
1497/* Assume a conservative default of 1200 bytes of payload per 4K page.
1498 * This may be adjusted later in tcp_measure_rcv_mss().
1499 */
1500#define TCP_DEFAULT_SCALING_RATIO ((1200 << TCP_RMEM_TO_WIN_SCALE) / \
1501 SKB_TRUESIZE(4096))
1502
1503static inline void tcp_scaling_ratio_init(struct sock *sk)
1504{
1505 tcp_sk(sk)->scaling_ratio = TCP_DEFAULT_SCALING_RATIO;
1506}
1507
1508/* Note: caller must be prepared to deal with negative returns */
1509static inline int tcp_space(const struct sock *sk)
1510{
1511 return tcp_win_from_space(sk, READ_ONCE(sk->sk_rcvbuf) -
1512 READ_ONCE(sk->sk_backlog.len) -
1513 atomic_read(&sk->sk_rmem_alloc));
1514}
1515
1516static inline int tcp_full_space(const struct sock *sk)
1517{
1518 return tcp_win_from_space(sk, READ_ONCE(sk->sk_rcvbuf));
1519}
1520
1521static inline void __tcp_adjust_rcv_ssthresh(struct sock *sk, u32 new_ssthresh)
1522{
1523 int unused_mem = sk_unused_reserved_mem(sk);
1524 struct tcp_sock *tp = tcp_sk(sk);
1525
1526 tp->rcv_ssthresh = min(tp->rcv_ssthresh, new_ssthresh);
1527 if (unused_mem)
1528 tp->rcv_ssthresh = max_t(u32, tp->rcv_ssthresh,
1529 tcp_win_from_space(sk, unused_mem));
1530}
1531
1532static inline void tcp_adjust_rcv_ssthresh(struct sock *sk)
1533{
1534 __tcp_adjust_rcv_ssthresh(sk, 4U * tcp_sk(sk)->advmss);
1535}
1536
1537void tcp_cleanup_rbuf(struct sock *sk, int copied);
1538void __tcp_cleanup_rbuf(struct sock *sk, int copied);
1539
1540
1541/* We provision sk_rcvbuf around 200% of sk_rcvlowat.
1542 * If 87.5 % (7/8) of the space has been consumed, we want to override
1543 * SO_RCVLOWAT constraint, since we are receiving skbs with too small
1544 * len/truesize ratio.
1545 */
1546static inline bool tcp_rmem_pressure(const struct sock *sk)
1547{
1548 int rcvbuf, threshold;
1549
1550 if (tcp_under_memory_pressure(sk))
1551 return true;
1552
1553 rcvbuf = READ_ONCE(sk->sk_rcvbuf);
1554 threshold = rcvbuf - (rcvbuf >> 3);
1555
1556 return atomic_read(&sk->sk_rmem_alloc) > threshold;
1557}
1558
1559static inline bool tcp_epollin_ready(const struct sock *sk, int target)
1560{
1561 const struct tcp_sock *tp = tcp_sk(sk);
1562 int avail = READ_ONCE(tp->rcv_nxt) - READ_ONCE(tp->copied_seq);
1563
1564 if (avail <= 0)
1565 return false;
1566
1567 return (avail >= target) || tcp_rmem_pressure(sk) ||
1568 (tcp_receive_window(tp) <= inet_csk(sk)->icsk_ack.rcv_mss);
1569}
1570
1571extern void tcp_openreq_init_rwin(struct request_sock *req,
1572 const struct sock *sk_listener,
1573 const struct dst_entry *dst);
1574
1575void tcp_enter_memory_pressure(struct sock *sk);
1576void tcp_leave_memory_pressure(struct sock *sk);
1577
1578static inline int keepalive_intvl_when(const struct tcp_sock *tp)
1579{
1580 struct net *net = sock_net((struct sock *)tp);
1581 int val;
1582
1583 /* Paired with WRITE_ONCE() in tcp_sock_set_keepintvl()
1584 * and do_tcp_setsockopt().
1585 */
1586 val = READ_ONCE(tp->keepalive_intvl);
1587
1588 return val ? : READ_ONCE(net->ipv4.sysctl_tcp_keepalive_intvl);
1589}
1590
1591static inline int keepalive_time_when(const struct tcp_sock *tp)
1592{
1593 struct net *net = sock_net((struct sock *)tp);
1594 int val;
1595
1596 /* Paired with WRITE_ONCE() in tcp_sock_set_keepidle_locked() */
1597 val = READ_ONCE(tp->keepalive_time);
1598
1599 return val ? : READ_ONCE(net->ipv4.sysctl_tcp_keepalive_time);
1600}
1601
1602static inline int keepalive_probes(const struct tcp_sock *tp)
1603{
1604 struct net *net = sock_net((struct sock *)tp);
1605 int val;
1606
1607 /* Paired with WRITE_ONCE() in tcp_sock_set_keepcnt()
1608 * and do_tcp_setsockopt().
1609 */
1610 val = READ_ONCE(tp->keepalive_probes);
1611
1612 return val ? : READ_ONCE(net->ipv4.sysctl_tcp_keepalive_probes);
1613}
1614
1615static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp)
1616{
1617 const struct inet_connection_sock *icsk = &tp->inet_conn;
1618
1619 return min_t(u32, tcp_jiffies32 - icsk->icsk_ack.lrcvtime,
1620 tcp_jiffies32 - tp->rcv_tstamp);
1621}
1622
1623static inline int tcp_fin_time(const struct sock *sk)
1624{
1625 int fin_timeout = tcp_sk(sk)->linger2 ? :
1626 READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_fin_timeout);
1627 const int rto = inet_csk(sk)->icsk_rto;
1628
1629 if (fin_timeout < (rto << 2) - (rto >> 1))
1630 fin_timeout = (rto << 2) - (rto >> 1);
1631
1632 return fin_timeout;
1633}
1634
1635static inline bool tcp_paws_check(const struct tcp_options_received *rx_opt,
1636 int paws_win)
1637{
1638 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win)
1639 return true;
1640 if (unlikely(!time_before32(ktime_get_seconds(),
1641 rx_opt->ts_recent_stamp + TCP_PAWS_WRAP)))
1642 return true;
1643 /*
1644 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0,
1645 * then following tcp messages have valid values. Ignore 0 value,
1646 * or else 'negative' tsval might forbid us to accept their packets.
1647 */
1648 if (!rx_opt->ts_recent)
1649 return true;
1650 return false;
1651}
1652
1653static inline bool tcp_paws_reject(const struct tcp_options_received *rx_opt,
1654 int rst)
1655{
1656 if (tcp_paws_check(rx_opt, 0))
1657 return false;
1658
1659 /* RST segments are not recommended to carry timestamp,
1660 and, if they do, it is recommended to ignore PAWS because
1661 "their cleanup function should take precedence over timestamps."
1662 Certainly, it is mistake. It is necessary to understand the reasons
1663 of this constraint to relax it: if peer reboots, clock may go
1664 out-of-sync and half-open connections will not be reset.
1665 Actually, the problem would be not existing if all
1666 the implementations followed draft about maintaining clock
1667 via reboots. Linux-2.2 DOES NOT!
1668
1669 However, we can relax time bounds for RST segments to MSL.
1670 */
1671 if (rst && !time_before32(ktime_get_seconds(),
1672 rx_opt->ts_recent_stamp + TCP_PAWS_MSL))
1673 return false;
1674 return true;
1675}
1676
1677bool tcp_oow_rate_limited(struct net *net, const struct sk_buff *skb,
1678 int mib_idx, u32 *last_oow_ack_time);
1679
1680static inline void tcp_mib_init(struct net *net)
1681{
1682 /* See RFC 2012 */
1683 TCP_ADD_STATS(net, TCP_MIB_RTOALGORITHM, 1);
1684 TCP_ADD_STATS(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ);
1685 TCP_ADD_STATS(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ);
1686 TCP_ADD_STATS(net, TCP_MIB_MAXCONN, -1);
1687}
1688
1689/* from STCP */
1690static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp)
1691{
1692 tp->lost_skb_hint = NULL;
1693}
1694
1695static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp)
1696{
1697 tcp_clear_retrans_hints_partial(tp);
1698 tp->retransmit_skb_hint = NULL;
1699}
1700
1701#define tcp_md5_addr tcp_ao_addr
1702
1703/* - key database */
1704struct tcp_md5sig_key {
1705 struct hlist_node node;
1706 u8 keylen;
1707 u8 family; /* AF_INET or AF_INET6 */
1708 u8 prefixlen;
1709 u8 flags;
1710 union tcp_md5_addr addr;
1711 int l3index; /* set if key added with L3 scope */
1712 u8 key[TCP_MD5SIG_MAXKEYLEN];
1713 struct rcu_head rcu;
1714};
1715
1716/* - sock block */
1717struct tcp_md5sig_info {
1718 struct hlist_head head;
1719 struct rcu_head rcu;
1720};
1721
1722/* - pseudo header */
1723struct tcp4_pseudohdr {
1724 __be32 saddr;
1725 __be32 daddr;
1726 __u8 pad;
1727 __u8 protocol;
1728 __be16 len;
1729};
1730
1731struct tcp6_pseudohdr {
1732 struct in6_addr saddr;
1733 struct in6_addr daddr;
1734 __be32 len;
1735 __be32 protocol; /* including padding */
1736};
1737
1738union tcp_md5sum_block {
1739 struct tcp4_pseudohdr ip4;
1740#if IS_ENABLED(CONFIG_IPV6)
1741 struct tcp6_pseudohdr ip6;
1742#endif
1743};
1744
1745/*
1746 * struct tcp_sigpool - per-CPU pool of ahash_requests
1747 * @scratch: per-CPU temporary area, that can be used between
1748 * tcp_sigpool_start() and tcp_sigpool_end() to perform
1749 * crypto request
1750 * @req: pre-allocated ahash request
1751 */
1752struct tcp_sigpool {
1753 void *scratch;
1754 struct ahash_request *req;
1755};
1756
1757int tcp_sigpool_alloc_ahash(const char *alg, size_t scratch_size);
1758void tcp_sigpool_get(unsigned int id);
1759void tcp_sigpool_release(unsigned int id);
1760int tcp_sigpool_hash_skb_data(struct tcp_sigpool *hp,
1761 const struct sk_buff *skb,
1762 unsigned int header_len);
1763
1764/**
1765 * tcp_sigpool_start - disable bh and start using tcp_sigpool_ahash
1766 * @id: tcp_sigpool that was previously allocated by tcp_sigpool_alloc_ahash()
1767 * @c: returned tcp_sigpool for usage (uninitialized on failure)
1768 *
1769 * Returns 0 on success, error otherwise.
1770 */
1771int tcp_sigpool_start(unsigned int id, struct tcp_sigpool *c);
1772/**
1773 * tcp_sigpool_end - enable bh and stop using tcp_sigpool
1774 * @c: tcp_sigpool context that was returned by tcp_sigpool_start()
1775 */
1776void tcp_sigpool_end(struct tcp_sigpool *c);
1777size_t tcp_sigpool_algo(unsigned int id, char *buf, size_t buf_len);
1778/* - functions */
1779int tcp_v4_md5_hash_skb(char *md5_hash, const struct tcp_md5sig_key *key,
1780 const struct sock *sk, const struct sk_buff *skb);
1781int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
1782 int family, u8 prefixlen, int l3index, u8 flags,
1783 const u8 *newkey, u8 newkeylen);
1784int tcp_md5_key_copy(struct sock *sk, const union tcp_md5_addr *addr,
1785 int family, u8 prefixlen, int l3index,
1786 struct tcp_md5sig_key *key);
1787
1788int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr,
1789 int family, u8 prefixlen, int l3index, u8 flags);
1790void tcp_clear_md5_list(struct sock *sk);
1791struct tcp_md5sig_key *tcp_v4_md5_lookup(const struct sock *sk,
1792 const struct sock *addr_sk);
1793
1794#ifdef CONFIG_TCP_MD5SIG
1795struct tcp_md5sig_key *__tcp_md5_do_lookup(const struct sock *sk, int l3index,
1796 const union tcp_md5_addr *addr,
1797 int family, bool any_l3index);
1798static inline struct tcp_md5sig_key *
1799tcp_md5_do_lookup(const struct sock *sk, int l3index,
1800 const union tcp_md5_addr *addr, int family)
1801{
1802 if (!static_branch_unlikely(&tcp_md5_needed.key))
1803 return NULL;
1804 return __tcp_md5_do_lookup(sk, l3index, addr, family, false);
1805}
1806
1807static inline struct tcp_md5sig_key *
1808tcp_md5_do_lookup_any_l3index(const struct sock *sk,
1809 const union tcp_md5_addr *addr, int family)
1810{
1811 if (!static_branch_unlikely(&tcp_md5_needed.key))
1812 return NULL;
1813 return __tcp_md5_do_lookup(sk, 0, addr, family, true);
1814}
1815
1816enum skb_drop_reason
1817tcp_inbound_md5_hash(const struct sock *sk, const struct sk_buff *skb,
1818 const void *saddr, const void *daddr,
1819 int family, int l3index, const __u8 *hash_location);
1820
1821
1822#define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key)
1823#else
1824static inline struct tcp_md5sig_key *
1825tcp_md5_do_lookup(const struct sock *sk, int l3index,
1826 const union tcp_md5_addr *addr, int family)
1827{
1828 return NULL;
1829}
1830
1831static inline struct tcp_md5sig_key *
1832tcp_md5_do_lookup_any_l3index(const struct sock *sk,
1833 const union tcp_md5_addr *addr, int family)
1834{
1835 return NULL;
1836}
1837
1838static inline enum skb_drop_reason
1839tcp_inbound_md5_hash(const struct sock *sk, const struct sk_buff *skb,
1840 const void *saddr, const void *daddr,
1841 int family, int l3index, const __u8 *hash_location)
1842{
1843 return SKB_NOT_DROPPED_YET;
1844}
1845#define tcp_twsk_md5_key(twsk) NULL
1846#endif
1847
1848int tcp_md5_alloc_sigpool(void);
1849void tcp_md5_release_sigpool(void);
1850void tcp_md5_add_sigpool(void);
1851extern int tcp_md5_sigpool_id;
1852
1853int tcp_md5_hash_key(struct tcp_sigpool *hp,
1854 const struct tcp_md5sig_key *key);
1855
1856/* From tcp_fastopen.c */
1857void tcp_fastopen_cache_get(struct sock *sk, u16 *mss,
1858 struct tcp_fastopen_cookie *cookie);
1859void tcp_fastopen_cache_set(struct sock *sk, u16 mss,
1860 struct tcp_fastopen_cookie *cookie, bool syn_lost,
1861 u16 try_exp);
1862struct tcp_fastopen_request {
1863 /* Fast Open cookie. Size 0 means a cookie request */
1864 struct tcp_fastopen_cookie cookie;
1865 struct msghdr *data; /* data in MSG_FASTOPEN */
1866 size_t size;
1867 int copied; /* queued in tcp_connect() */
1868 struct ubuf_info *uarg;
1869};
1870void tcp_free_fastopen_req(struct tcp_sock *tp);
1871void tcp_fastopen_destroy_cipher(struct sock *sk);
1872void tcp_fastopen_ctx_destroy(struct net *net);
1873int tcp_fastopen_reset_cipher(struct net *net, struct sock *sk,
1874 void *primary_key, void *backup_key);
1875int tcp_fastopen_get_cipher(struct net *net, struct inet_connection_sock *icsk,
1876 u64 *key);
1877void tcp_fastopen_add_skb(struct sock *sk, struct sk_buff *skb);
1878struct sock *tcp_try_fastopen(struct sock *sk, struct sk_buff *skb,
1879 struct request_sock *req,
1880 struct tcp_fastopen_cookie *foc,
1881 const struct dst_entry *dst);
1882void tcp_fastopen_init_key_once(struct net *net);
1883bool tcp_fastopen_cookie_check(struct sock *sk, u16 *mss,
1884 struct tcp_fastopen_cookie *cookie);
1885bool tcp_fastopen_defer_connect(struct sock *sk, int *err);
1886#define TCP_FASTOPEN_KEY_LENGTH sizeof(siphash_key_t)
1887#define TCP_FASTOPEN_KEY_MAX 2
1888#define TCP_FASTOPEN_KEY_BUF_LENGTH \
1889 (TCP_FASTOPEN_KEY_LENGTH * TCP_FASTOPEN_KEY_MAX)
1890
1891/* Fastopen key context */
1892struct tcp_fastopen_context {
1893 siphash_key_t key[TCP_FASTOPEN_KEY_MAX];
1894 int num;
1895 struct rcu_head rcu;
1896};
1897
1898void tcp_fastopen_active_disable(struct sock *sk);
1899bool tcp_fastopen_active_should_disable(struct sock *sk);
1900void tcp_fastopen_active_disable_ofo_check(struct sock *sk);
1901void tcp_fastopen_active_detect_blackhole(struct sock *sk, bool expired);
1902
1903/* Caller needs to wrap with rcu_read_(un)lock() */
1904static inline
1905struct tcp_fastopen_context *tcp_fastopen_get_ctx(const struct sock *sk)
1906{
1907 struct tcp_fastopen_context *ctx;
1908
1909 ctx = rcu_dereference(inet_csk(sk)->icsk_accept_queue.fastopenq.ctx);
1910 if (!ctx)
1911 ctx = rcu_dereference(sock_net(sk)->ipv4.tcp_fastopen_ctx);
1912 return ctx;
1913}
1914
1915static inline
1916bool tcp_fastopen_cookie_match(const struct tcp_fastopen_cookie *foc,
1917 const struct tcp_fastopen_cookie *orig)
1918{
1919 if (orig->len == TCP_FASTOPEN_COOKIE_SIZE &&
1920 orig->len == foc->len &&
1921 !memcmp(orig->val, foc->val, foc->len))
1922 return true;
1923 return false;
1924}
1925
1926static inline
1927int tcp_fastopen_context_len(const struct tcp_fastopen_context *ctx)
1928{
1929 return ctx->num;
1930}
1931
1932/* Latencies incurred by various limits for a sender. They are
1933 * chronograph-like stats that are mutually exclusive.
1934 */
1935enum tcp_chrono {
1936 TCP_CHRONO_UNSPEC,
1937 TCP_CHRONO_BUSY, /* Actively sending data (non-empty write queue) */
1938 TCP_CHRONO_RWND_LIMITED, /* Stalled by insufficient receive window */
1939 TCP_CHRONO_SNDBUF_LIMITED, /* Stalled by insufficient send buffer */
1940 __TCP_CHRONO_MAX,
1941};
1942
1943void tcp_chrono_start(struct sock *sk, const enum tcp_chrono type);
1944void tcp_chrono_stop(struct sock *sk, const enum tcp_chrono type);
1945
1946/* This helper is needed, because skb->tcp_tsorted_anchor uses
1947 * the same memory storage than skb->destructor/_skb_refdst
1948 */
1949static inline void tcp_skb_tsorted_anchor_cleanup(struct sk_buff *skb)
1950{
1951 skb->destructor = NULL;
1952 skb->_skb_refdst = 0UL;
1953}
1954
1955#define tcp_skb_tsorted_save(skb) { \
1956 unsigned long _save = skb->_skb_refdst; \
1957 skb->_skb_refdst = 0UL;
1958
1959#define tcp_skb_tsorted_restore(skb) \
1960 skb->_skb_refdst = _save; \
1961}
1962
1963void tcp_write_queue_purge(struct sock *sk);
1964
1965static inline struct sk_buff *tcp_rtx_queue_head(const struct sock *sk)
1966{
1967 return skb_rb_first(&sk->tcp_rtx_queue);
1968}
1969
1970static inline struct sk_buff *tcp_rtx_queue_tail(const struct sock *sk)
1971{
1972 return skb_rb_last(&sk->tcp_rtx_queue);
1973}
1974
1975static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk)
1976{
1977 return skb_peek_tail(&sk->sk_write_queue);
1978}
1979
1980#define tcp_for_write_queue_from_safe(skb, tmp, sk) \
1981 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp)
1982
1983static inline struct sk_buff *tcp_send_head(const struct sock *sk)
1984{
1985 return skb_peek(&sk->sk_write_queue);
1986}
1987
1988static inline bool tcp_skb_is_last(const struct sock *sk,
1989 const struct sk_buff *skb)
1990{
1991 return skb_queue_is_last(&sk->sk_write_queue, skb);
1992}
1993
1994/**
1995 * tcp_write_queue_empty - test if any payload (or FIN) is available in write queue
1996 * @sk: socket
1997 *
1998 * Since the write queue can have a temporary empty skb in it,
1999 * we must not use "return skb_queue_empty(&sk->sk_write_queue)"
2000 */
2001static inline bool tcp_write_queue_empty(const struct sock *sk)
2002{
2003 const struct tcp_sock *tp = tcp_sk(sk);
2004
2005 return tp->write_seq == tp->snd_nxt;
2006}
2007
2008static inline bool tcp_rtx_queue_empty(const struct sock *sk)
2009{
2010 return RB_EMPTY_ROOT(&sk->tcp_rtx_queue);
2011}
2012
2013static inline bool tcp_rtx_and_write_queues_empty(const struct sock *sk)
2014{
2015 return tcp_rtx_queue_empty(sk) && tcp_write_queue_empty(sk);
2016}
2017
2018static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
2019{
2020 __skb_queue_tail(&sk->sk_write_queue, skb);
2021
2022 /* Queue it, remembering where we must start sending. */
2023 if (sk->sk_write_queue.next == skb)
2024 tcp_chrono_start(sk, TCP_CHRONO_BUSY);
2025}
2026
2027/* Insert new before skb on the write queue of sk. */
2028static inline void tcp_insert_write_queue_before(struct sk_buff *new,
2029 struct sk_buff *skb,
2030 struct sock *sk)
2031{
2032 __skb_queue_before(&sk->sk_write_queue, skb, new);
2033}
2034
2035static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk)
2036{
2037 tcp_skb_tsorted_anchor_cleanup(skb);
2038 __skb_unlink(skb, &sk->sk_write_queue);
2039}
2040
2041void tcp_rbtree_insert(struct rb_root *root, struct sk_buff *skb);
2042
2043static inline void tcp_rtx_queue_unlink(struct sk_buff *skb, struct sock *sk)
2044{
2045 tcp_skb_tsorted_anchor_cleanup(skb);
2046 rb_erase(&skb->rbnode, &sk->tcp_rtx_queue);
2047}
2048
2049static inline void tcp_rtx_queue_unlink_and_free(struct sk_buff *skb, struct sock *sk)
2050{
2051 list_del(&skb->tcp_tsorted_anchor);
2052 tcp_rtx_queue_unlink(skb, sk);
2053 tcp_wmem_free_skb(sk, skb);
2054}
2055
2056static inline void tcp_push_pending_frames(struct sock *sk)
2057{
2058 if (tcp_send_head(sk)) {
2059 struct tcp_sock *tp = tcp_sk(sk);
2060
2061 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle);
2062 }
2063}
2064
2065/* Start sequence of the skb just after the highest skb with SACKed
2066 * bit, valid only if sacked_out > 0 or when the caller has ensured
2067 * validity by itself.
2068 */
2069static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp)
2070{
2071 if (!tp->sacked_out)
2072 return tp->snd_una;
2073
2074 if (tp->highest_sack == NULL)
2075 return tp->snd_nxt;
2076
2077 return TCP_SKB_CB(tp->highest_sack)->seq;
2078}
2079
2080static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb)
2081{
2082 tcp_sk(sk)->highest_sack = skb_rb_next(skb);
2083}
2084
2085static inline struct sk_buff *tcp_highest_sack(struct sock *sk)
2086{
2087 return tcp_sk(sk)->highest_sack;
2088}
2089
2090static inline void tcp_highest_sack_reset(struct sock *sk)
2091{
2092 tcp_sk(sk)->highest_sack = tcp_rtx_queue_head(sk);
2093}
2094
2095/* Called when old skb is about to be deleted and replaced by new skb */
2096static inline void tcp_highest_sack_replace(struct sock *sk,
2097 struct sk_buff *old,
2098 struct sk_buff *new)
2099{
2100 if (old == tcp_highest_sack(sk))
2101 tcp_sk(sk)->highest_sack = new;
2102}
2103
2104/* This helper checks if socket has IP_TRANSPARENT set */
2105static inline bool inet_sk_transparent(const struct sock *sk)
2106{
2107 switch (sk->sk_state) {
2108 case TCP_TIME_WAIT:
2109 return inet_twsk(sk)->tw_transparent;
2110 case TCP_NEW_SYN_RECV:
2111 return inet_rsk(inet_reqsk(sk))->no_srccheck;
2112 }
2113 return inet_test_bit(TRANSPARENT, sk);
2114}
2115
2116/* Determines whether this is a thin stream (which may suffer from
2117 * increased latency). Used to trigger latency-reducing mechanisms.
2118 */
2119static inline bool tcp_stream_is_thin(struct tcp_sock *tp)
2120{
2121 return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp);
2122}
2123
2124/* /proc */
2125enum tcp_seq_states {
2126 TCP_SEQ_STATE_LISTENING,
2127 TCP_SEQ_STATE_ESTABLISHED,
2128};
2129
2130void *tcp_seq_start(struct seq_file *seq, loff_t *pos);
2131void *tcp_seq_next(struct seq_file *seq, void *v, loff_t *pos);
2132void tcp_seq_stop(struct seq_file *seq, void *v);
2133
2134struct tcp_seq_afinfo {
2135 sa_family_t family;
2136};
2137
2138struct tcp_iter_state {
2139 struct seq_net_private p;
2140 enum tcp_seq_states state;
2141 struct sock *syn_wait_sk;
2142 int bucket, offset, sbucket, num;
2143 loff_t last_pos;
2144};
2145
2146extern struct request_sock_ops tcp_request_sock_ops;
2147extern struct request_sock_ops tcp6_request_sock_ops;
2148
2149void tcp_v4_destroy_sock(struct sock *sk);
2150
2151struct sk_buff *tcp_gso_segment(struct sk_buff *skb,
2152 netdev_features_t features);
2153struct sk_buff *tcp_gro_receive(struct list_head *head, struct sk_buff *skb);
2154INDIRECT_CALLABLE_DECLARE(int tcp4_gro_complete(struct sk_buff *skb, int thoff));
2155INDIRECT_CALLABLE_DECLARE(struct sk_buff *tcp4_gro_receive(struct list_head *head, struct sk_buff *skb));
2156INDIRECT_CALLABLE_DECLARE(int tcp6_gro_complete(struct sk_buff *skb, int thoff));
2157INDIRECT_CALLABLE_DECLARE(struct sk_buff *tcp6_gro_receive(struct list_head *head, struct sk_buff *skb));
2158#ifdef CONFIG_INET
2159void tcp_gro_complete(struct sk_buff *skb);
2160#else
2161static inline void tcp_gro_complete(struct sk_buff *skb) { }
2162#endif
2163
2164void __tcp_v4_send_check(struct sk_buff *skb, __be32 saddr, __be32 daddr);
2165
2166static inline u32 tcp_notsent_lowat(const struct tcp_sock *tp)
2167{
2168 struct net *net = sock_net((struct sock *)tp);
2169 u32 val;
2170
2171 val = READ_ONCE(tp->notsent_lowat);
2172
2173 return val ?: READ_ONCE(net->ipv4.sysctl_tcp_notsent_lowat);
2174}
2175
2176bool tcp_stream_memory_free(const struct sock *sk, int wake);
2177
2178#ifdef CONFIG_PROC_FS
2179int tcp4_proc_init(void);
2180void tcp4_proc_exit(void);
2181#endif
2182
2183int tcp_rtx_synack(const struct sock *sk, struct request_sock *req);
2184int tcp_conn_request(struct request_sock_ops *rsk_ops,
2185 const struct tcp_request_sock_ops *af_ops,
2186 struct sock *sk, struct sk_buff *skb);
2187
2188/* TCP af-specific functions */
2189struct tcp_sock_af_ops {
2190#ifdef CONFIG_TCP_MD5SIG
2191 struct tcp_md5sig_key *(*md5_lookup) (const struct sock *sk,
2192 const struct sock *addr_sk);
2193 int (*calc_md5_hash)(char *location,
2194 const struct tcp_md5sig_key *md5,
2195 const struct sock *sk,
2196 const struct sk_buff *skb);
2197 int (*md5_parse)(struct sock *sk,
2198 int optname,
2199 sockptr_t optval,
2200 int optlen);
2201#endif
2202#ifdef CONFIG_TCP_AO
2203 int (*ao_parse)(struct sock *sk, int optname, sockptr_t optval, int optlen);
2204 struct tcp_ao_key *(*ao_lookup)(const struct sock *sk,
2205 struct sock *addr_sk,
2206 int sndid, int rcvid);
2207 int (*ao_calc_key_sk)(struct tcp_ao_key *mkt, u8 *key,
2208 const struct sock *sk,
2209 __be32 sisn, __be32 disn, bool send);
2210 int (*calc_ao_hash)(char *location, struct tcp_ao_key *ao,
2211 const struct sock *sk, const struct sk_buff *skb,
2212 const u8 *tkey, int hash_offset, u32 sne);
2213#endif
2214};
2215
2216struct tcp_request_sock_ops {
2217 u16 mss_clamp;
2218#ifdef CONFIG_TCP_MD5SIG
2219 struct tcp_md5sig_key *(*req_md5_lookup)(const struct sock *sk,
2220 const struct sock *addr_sk);
2221 int (*calc_md5_hash) (char *location,
2222 const struct tcp_md5sig_key *md5,
2223 const struct sock *sk,
2224 const struct sk_buff *skb);
2225#endif
2226#ifdef CONFIG_TCP_AO
2227 struct tcp_ao_key *(*ao_lookup)(const struct sock *sk,
2228 struct request_sock *req,
2229 int sndid, int rcvid);
2230 int (*ao_calc_key)(struct tcp_ao_key *mkt, u8 *key, struct request_sock *sk);
2231 int (*ao_synack_hash)(char *ao_hash, struct tcp_ao_key *mkt,
2232 struct request_sock *req, const struct sk_buff *skb,
2233 int hash_offset, u32 sne);
2234#endif
2235#ifdef CONFIG_SYN_COOKIES
2236 __u32 (*cookie_init_seq)(const struct sk_buff *skb,
2237 __u16 *mss);
2238#endif
2239 struct dst_entry *(*route_req)(const struct sock *sk,
2240 struct sk_buff *skb,
2241 struct flowi *fl,
2242 struct request_sock *req);
2243 u32 (*init_seq)(const struct sk_buff *skb);
2244 u32 (*init_ts_off)(const struct net *net, const struct sk_buff *skb);
2245 int (*send_synack)(const struct sock *sk, struct dst_entry *dst,
2246 struct flowi *fl, struct request_sock *req,
2247 struct tcp_fastopen_cookie *foc,
2248 enum tcp_synack_type synack_type,
2249 struct sk_buff *syn_skb);
2250};
2251
2252extern const struct tcp_request_sock_ops tcp_request_sock_ipv4_ops;
2253#if IS_ENABLED(CONFIG_IPV6)
2254extern const struct tcp_request_sock_ops tcp_request_sock_ipv6_ops;
2255#endif
2256
2257#ifdef CONFIG_SYN_COOKIES
2258static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops,
2259 const struct sock *sk, struct sk_buff *skb,
2260 __u16 *mss)
2261{
2262 tcp_synq_overflow(sk);
2263 __NET_INC_STATS(sock_net(sk), LINUX_MIB_SYNCOOKIESSENT);
2264 return ops->cookie_init_seq(skb, mss);
2265}
2266#else
2267static inline __u32 cookie_init_sequence(const struct tcp_request_sock_ops *ops,
2268 const struct sock *sk, struct sk_buff *skb,
2269 __u16 *mss)
2270{
2271 return 0;
2272}
2273#endif
2274
2275struct tcp_key {
2276 union {
2277 struct {
2278 struct tcp_ao_key *ao_key;
2279 char *traffic_key;
2280 u32 sne;
2281 u8 rcv_next;
2282 };
2283 struct tcp_md5sig_key *md5_key;
2284 };
2285 enum {
2286 TCP_KEY_NONE = 0,
2287 TCP_KEY_MD5,
2288 TCP_KEY_AO,
2289 } type;
2290};
2291
2292static inline void tcp_get_current_key(const struct sock *sk,
2293 struct tcp_key *out)
2294{
2295#if defined(CONFIG_TCP_AO) || defined(CONFIG_TCP_MD5SIG)
2296 const struct tcp_sock *tp = tcp_sk(sk);
2297#endif
2298
2299#ifdef CONFIG_TCP_AO
2300 if (static_branch_unlikely(&tcp_ao_needed.key)) {
2301 struct tcp_ao_info *ao;
2302
2303 ao = rcu_dereference_protected(tp->ao_info,
2304 lockdep_sock_is_held(sk));
2305 if (ao) {
2306 out->ao_key = READ_ONCE(ao->current_key);
2307 out->type = TCP_KEY_AO;
2308 return;
2309 }
2310 }
2311#endif
2312#ifdef CONFIG_TCP_MD5SIG
2313 if (static_branch_unlikely(&tcp_md5_needed.key) &&
2314 rcu_access_pointer(tp->md5sig_info)) {
2315 out->md5_key = tp->af_specific->md5_lookup(sk, sk);
2316 if (out->md5_key) {
2317 out->type = TCP_KEY_MD5;
2318 return;
2319 }
2320 }
2321#endif
2322 out->type = TCP_KEY_NONE;
2323}
2324
2325static inline bool tcp_key_is_md5(const struct tcp_key *key)
2326{
2327#ifdef CONFIG_TCP_MD5SIG
2328 if (static_branch_unlikely(&tcp_md5_needed.key) &&
2329 key->type == TCP_KEY_MD5)
2330 return true;
2331#endif
2332 return false;
2333}
2334
2335static inline bool tcp_key_is_ao(const struct tcp_key *key)
2336{
2337#ifdef CONFIG_TCP_AO
2338 if (static_branch_unlikely(&tcp_ao_needed.key) &&
2339 key->type == TCP_KEY_AO)
2340 return true;
2341#endif
2342 return false;
2343}
2344
2345int tcpv4_offload_init(void);
2346
2347void tcp_v4_init(void);
2348void tcp_init(void);
2349
2350/* tcp_recovery.c */
2351void tcp_mark_skb_lost(struct sock *sk, struct sk_buff *skb);
2352void tcp_newreno_mark_lost(struct sock *sk, bool snd_una_advanced);
2353extern s32 tcp_rack_skb_timeout(struct tcp_sock *tp, struct sk_buff *skb,
2354 u32 reo_wnd);
2355extern bool tcp_rack_mark_lost(struct sock *sk);
2356extern void tcp_rack_advance(struct tcp_sock *tp, u8 sacked, u32 end_seq,
2357 u64 xmit_time);
2358extern void tcp_rack_reo_timeout(struct sock *sk);
2359extern void tcp_rack_update_reo_wnd(struct sock *sk, struct rate_sample *rs);
2360
2361/* tcp_plb.c */
2362
2363/*
2364 * Scaling factor for fractions in PLB. For example, tcp_plb_update_state
2365 * expects cong_ratio which represents fraction of traffic that experienced
2366 * congestion over a single RTT. In order to avoid floating point operations,
2367 * this fraction should be mapped to (1 << TCP_PLB_SCALE) and passed in.
2368 */
2369#define TCP_PLB_SCALE 8
2370
2371/* State for PLB (Protective Load Balancing) for a single TCP connection. */
2372struct tcp_plb_state {
2373 u8 consec_cong_rounds:5, /* consecutive congested rounds */
2374 unused:3;
2375 u32 pause_until; /* jiffies32 when PLB can resume rerouting */
2376};
2377
2378static inline void tcp_plb_init(const struct sock *sk,
2379 struct tcp_plb_state *plb)
2380{
2381 plb->consec_cong_rounds = 0;
2382 plb->pause_until = 0;
2383}
2384void tcp_plb_update_state(const struct sock *sk, struct tcp_plb_state *plb,
2385 const int cong_ratio);
2386void tcp_plb_check_rehash(struct sock *sk, struct tcp_plb_state *plb);
2387void tcp_plb_update_state_upon_rto(struct sock *sk, struct tcp_plb_state *plb);
2388
2389/* At how many usecs into the future should the RTO fire? */
2390static inline s64 tcp_rto_delta_us(const struct sock *sk)
2391{
2392 const struct sk_buff *skb = tcp_rtx_queue_head(sk);
2393 u32 rto = inet_csk(sk)->icsk_rto;
2394 u64 rto_time_stamp_us = tcp_skb_timestamp_us(skb) + jiffies_to_usecs(rto);
2395
2396 return rto_time_stamp_us - tcp_sk(sk)->tcp_mstamp;
2397}
2398
2399/*
2400 * Save and compile IPv4 options, return a pointer to it
2401 */
2402static inline struct ip_options_rcu *tcp_v4_save_options(struct net *net,
2403 struct sk_buff *skb)
2404{
2405 const struct ip_options *opt = &TCP_SKB_CB(skb)->header.h4.opt;
2406 struct ip_options_rcu *dopt = NULL;
2407
2408 if (opt->optlen) {
2409 int opt_size = sizeof(*dopt) + opt->optlen;
2410
2411 dopt = kmalloc(opt_size, GFP_ATOMIC);
2412 if (dopt && __ip_options_echo(net, &dopt->opt, skb, opt)) {
2413 kfree(dopt);
2414 dopt = NULL;
2415 }
2416 }
2417 return dopt;
2418}
2419
2420/* locally generated TCP pure ACKs have skb->truesize == 2
2421 * (check tcp_send_ack() in net/ipv4/tcp_output.c )
2422 * This is much faster than dissecting the packet to find out.
2423 * (Think of GRE encapsulations, IPv4, IPv6, ...)
2424 */
2425static inline bool skb_is_tcp_pure_ack(const struct sk_buff *skb)
2426{
2427 return skb->truesize == 2;
2428}
2429
2430static inline void skb_set_tcp_pure_ack(struct sk_buff *skb)
2431{
2432 skb->truesize = 2;
2433}
2434
2435static inline int tcp_inq(struct sock *sk)
2436{
2437 struct tcp_sock *tp = tcp_sk(sk);
2438 int answ;
2439
2440 if ((1 << sk->sk_state) & (TCPF_SYN_SENT | TCPF_SYN_RECV)) {
2441 answ = 0;
2442 } else if (sock_flag(sk, SOCK_URGINLINE) ||
2443 !tp->urg_data ||
2444 before(tp->urg_seq, tp->copied_seq) ||
2445 !before(tp->urg_seq, tp->rcv_nxt)) {
2446
2447 answ = tp->rcv_nxt - tp->copied_seq;
2448
2449 /* Subtract 1, if FIN was received */
2450 if (answ && sock_flag(sk, SOCK_DONE))
2451 answ--;
2452 } else {
2453 answ = tp->urg_seq - tp->copied_seq;
2454 }
2455
2456 return answ;
2457}
2458
2459int tcp_peek_len(struct socket *sock);
2460
2461static inline void tcp_segs_in(struct tcp_sock *tp, const struct sk_buff *skb)
2462{
2463 u16 segs_in;
2464
2465 segs_in = max_t(u16, 1, skb_shinfo(skb)->gso_segs);
2466
2467 /* We update these fields while other threads might
2468 * read them from tcp_get_info()
2469 */
2470 WRITE_ONCE(tp->segs_in, tp->segs_in + segs_in);
2471 if (skb->len > tcp_hdrlen(skb))
2472 WRITE_ONCE(tp->data_segs_in, tp->data_segs_in + segs_in);
2473}
2474
2475/*
2476 * TCP listen path runs lockless.
2477 * We forced "struct sock" to be const qualified to make sure
2478 * we don't modify one of its field by mistake.
2479 * Here, we increment sk_drops which is an atomic_t, so we can safely
2480 * make sock writable again.
2481 */
2482static inline void tcp_listendrop(const struct sock *sk)
2483{
2484 atomic_inc(&((struct sock *)sk)->sk_drops);
2485 __NET_INC_STATS(sock_net(sk), LINUX_MIB_LISTENDROPS);
2486}
2487
2488enum hrtimer_restart tcp_pace_kick(struct hrtimer *timer);
2489
2490/*
2491 * Interface for adding Upper Level Protocols over TCP
2492 */
2493
2494#define TCP_ULP_NAME_MAX 16
2495#define TCP_ULP_MAX 128
2496#define TCP_ULP_BUF_MAX (TCP_ULP_NAME_MAX*TCP_ULP_MAX)
2497
2498struct tcp_ulp_ops {
2499 struct list_head list;
2500
2501 /* initialize ulp */
2502 int (*init)(struct sock *sk);
2503 /* update ulp */
2504 void (*update)(struct sock *sk, struct proto *p,
2505 void (*write_space)(struct sock *sk));
2506 /* cleanup ulp */
2507 void (*release)(struct sock *sk);
2508 /* diagnostic */
2509 int (*get_info)(struct sock *sk, struct sk_buff *skb);
2510 size_t (*get_info_size)(const struct sock *sk);
2511 /* clone ulp */
2512 void (*clone)(const struct request_sock *req, struct sock *newsk,
2513 const gfp_t priority);
2514
2515 char name[TCP_ULP_NAME_MAX];
2516 struct module *owner;
2517};
2518int tcp_register_ulp(struct tcp_ulp_ops *type);
2519void tcp_unregister_ulp(struct tcp_ulp_ops *type);
2520int tcp_set_ulp(struct sock *sk, const char *name);
2521void tcp_get_available_ulp(char *buf, size_t len);
2522void tcp_cleanup_ulp(struct sock *sk);
2523void tcp_update_ulp(struct sock *sk, struct proto *p,
2524 void (*write_space)(struct sock *sk));
2525
2526#define MODULE_ALIAS_TCP_ULP(name) \
2527 __MODULE_INFO(alias, alias_userspace, name); \
2528 __MODULE_INFO(alias, alias_tcp_ulp, "tcp-ulp-" name)
2529
2530#ifdef CONFIG_NET_SOCK_MSG
2531struct sk_msg;
2532struct sk_psock;
2533
2534#ifdef CONFIG_BPF_SYSCALL
2535int tcp_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore);
2536void tcp_bpf_clone(const struct sock *sk, struct sock *newsk);
2537#endif /* CONFIG_BPF_SYSCALL */
2538
2539#ifdef CONFIG_INET
2540void tcp_eat_skb(struct sock *sk, struct sk_buff *skb);
2541#else
2542static inline void tcp_eat_skb(struct sock *sk, struct sk_buff *skb)
2543{
2544}
2545#endif
2546
2547int tcp_bpf_sendmsg_redir(struct sock *sk, bool ingress,
2548 struct sk_msg *msg, u32 bytes, int flags);
2549#endif /* CONFIG_NET_SOCK_MSG */
2550
2551#if !defined(CONFIG_BPF_SYSCALL) || !defined(CONFIG_NET_SOCK_MSG)
2552static inline void tcp_bpf_clone(const struct sock *sk, struct sock *newsk)
2553{
2554}
2555#endif
2556
2557#ifdef CONFIG_CGROUP_BPF
2558static inline void bpf_skops_init_skb(struct bpf_sock_ops_kern *skops,
2559 struct sk_buff *skb,
2560 unsigned int end_offset)
2561{
2562 skops->skb = skb;
2563 skops->skb_data_end = skb->data + end_offset;
2564}
2565#else
2566static inline void bpf_skops_init_skb(struct bpf_sock_ops_kern *skops,
2567 struct sk_buff *skb,
2568 unsigned int end_offset)
2569{
2570}
2571#endif
2572
2573/* Call BPF_SOCK_OPS program that returns an int. If the return value
2574 * is < 0, then the BPF op failed (for example if the loaded BPF
2575 * program does not support the chosen operation or there is no BPF
2576 * program loaded).
2577 */
2578#ifdef CONFIG_BPF
2579static inline int tcp_call_bpf(struct sock *sk, int op, u32 nargs, u32 *args)
2580{
2581 struct bpf_sock_ops_kern sock_ops;
2582 int ret;
2583
2584 memset(&sock_ops, 0, offsetof(struct bpf_sock_ops_kern, temp));
2585 if (sk_fullsock(sk)) {
2586 sock_ops.is_fullsock = 1;
2587 sock_owned_by_me(sk);
2588 }
2589
2590 sock_ops.sk = sk;
2591 sock_ops.op = op;
2592 if (nargs > 0)
2593 memcpy(sock_ops.args, args, nargs * sizeof(*args));
2594
2595 ret = BPF_CGROUP_RUN_PROG_SOCK_OPS(&sock_ops);
2596 if (ret == 0)
2597 ret = sock_ops.reply;
2598 else
2599 ret = -1;
2600 return ret;
2601}
2602
2603static inline int tcp_call_bpf_2arg(struct sock *sk, int op, u32 arg1, u32 arg2)
2604{
2605 u32 args[2] = {arg1, arg2};
2606
2607 return tcp_call_bpf(sk, op, 2, args);
2608}
2609
2610static inline int tcp_call_bpf_3arg(struct sock *sk, int op, u32 arg1, u32 arg2,
2611 u32 arg3)
2612{
2613 u32 args[3] = {arg1, arg2, arg3};
2614
2615 return tcp_call_bpf(sk, op, 3, args);
2616}
2617
2618#else
2619static inline int tcp_call_bpf(struct sock *sk, int op, u32 nargs, u32 *args)
2620{
2621 return -EPERM;
2622}
2623
2624static inline int tcp_call_bpf_2arg(struct sock *sk, int op, u32 arg1, u32 arg2)
2625{
2626 return -EPERM;
2627}
2628
2629static inline int tcp_call_bpf_3arg(struct sock *sk, int op, u32 arg1, u32 arg2,
2630 u32 arg3)
2631{
2632 return -EPERM;
2633}
2634
2635#endif
2636
2637static inline u32 tcp_timeout_init(struct sock *sk)
2638{
2639 int timeout;
2640
2641 timeout = tcp_call_bpf(sk, BPF_SOCK_OPS_TIMEOUT_INIT, 0, NULL);
2642
2643 if (timeout <= 0)
2644 timeout = TCP_TIMEOUT_INIT;
2645 return min_t(int, timeout, TCP_RTO_MAX);
2646}
2647
2648static inline u32 tcp_rwnd_init_bpf(struct sock *sk)
2649{
2650 int rwnd;
2651
2652 rwnd = tcp_call_bpf(sk, BPF_SOCK_OPS_RWND_INIT, 0, NULL);
2653
2654 if (rwnd < 0)
2655 rwnd = 0;
2656 return rwnd;
2657}
2658
2659static inline bool tcp_bpf_ca_needs_ecn(struct sock *sk)
2660{
2661 return (tcp_call_bpf(sk, BPF_SOCK_OPS_NEEDS_ECN, 0, NULL) == 1);
2662}
2663
2664static inline void tcp_bpf_rtt(struct sock *sk)
2665{
2666 if (BPF_SOCK_OPS_TEST_FLAG(tcp_sk(sk), BPF_SOCK_OPS_RTT_CB_FLAG))
2667 tcp_call_bpf(sk, BPF_SOCK_OPS_RTT_CB, 0, NULL);
2668}
2669
2670#if IS_ENABLED(CONFIG_SMC)
2671extern struct static_key_false tcp_have_smc;
2672#endif
2673
2674#if IS_ENABLED(CONFIG_TLS_DEVICE)
2675void clean_acked_data_enable(struct inet_connection_sock *icsk,
2676 void (*cad)(struct sock *sk, u32 ack_seq));
2677void clean_acked_data_disable(struct inet_connection_sock *icsk);
2678void clean_acked_data_flush(void);
2679#endif
2680
2681DECLARE_STATIC_KEY_FALSE(tcp_tx_delay_enabled);
2682static inline void tcp_add_tx_delay(struct sk_buff *skb,
2683 const struct tcp_sock *tp)
2684{
2685 if (static_branch_unlikely(&tcp_tx_delay_enabled))
2686 skb->skb_mstamp_ns += (u64)tp->tcp_tx_delay * NSEC_PER_USEC;
2687}
2688
2689/* Compute Earliest Departure Time for some control packets
2690 * like ACK or RST for TIME_WAIT or non ESTABLISHED sockets.
2691 */
2692static inline u64 tcp_transmit_time(const struct sock *sk)
2693{
2694 if (static_branch_unlikely(&tcp_tx_delay_enabled)) {
2695 u32 delay = (sk->sk_state == TCP_TIME_WAIT) ?
2696 tcp_twsk(sk)->tw_tx_delay : tcp_sk(sk)->tcp_tx_delay;
2697
2698 return tcp_clock_ns() + (u64)delay * NSEC_PER_USEC;
2699 }
2700 return 0;
2701}
2702
2703static inline int tcp_parse_auth_options(const struct tcphdr *th,
2704 const u8 **md5_hash, const struct tcp_ao_hdr **aoh)
2705{
2706 const u8 *md5_tmp, *ao_tmp;
2707 int ret;
2708
2709 ret = tcp_do_parse_auth_options(th, &md5_tmp, &ao_tmp);
2710 if (ret)
2711 return ret;
2712
2713 if (md5_hash)
2714 *md5_hash = md5_tmp;
2715
2716 if (aoh) {
2717 if (!ao_tmp)
2718 *aoh = NULL;
2719 else
2720 *aoh = (struct tcp_ao_hdr *)(ao_tmp - 2);
2721 }
2722
2723 return 0;
2724}
2725
2726static inline bool tcp_ao_required(struct sock *sk, const void *saddr,
2727 int family, int l3index, bool stat_inc)
2728{
2729#ifdef CONFIG_TCP_AO
2730 struct tcp_ao_info *ao_info;
2731 struct tcp_ao_key *ao_key;
2732
2733 if (!static_branch_unlikely(&tcp_ao_needed.key))
2734 return false;
2735
2736 ao_info = rcu_dereference_check(tcp_sk(sk)->ao_info,
2737 lockdep_sock_is_held(sk));
2738 if (!ao_info)
2739 return false;
2740
2741 ao_key = tcp_ao_do_lookup(sk, l3index, saddr, family, -1, -1);
2742 if (ao_info->ao_required || ao_key) {
2743 if (stat_inc) {
2744 NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPAOREQUIRED);
2745 atomic64_inc(&ao_info->counters.ao_required);
2746 }
2747 return true;
2748 }
2749#endif
2750 return false;
2751}
2752
2753/* Called with rcu_read_lock() */
2754static inline enum skb_drop_reason
2755tcp_inbound_hash(struct sock *sk, const struct request_sock *req,
2756 const struct sk_buff *skb,
2757 const void *saddr, const void *daddr,
2758 int family, int dif, int sdif)
2759{
2760 const struct tcphdr *th = tcp_hdr(skb);
2761 const struct tcp_ao_hdr *aoh;
2762 const __u8 *md5_location;
2763 int l3index;
2764
2765 /* Invalid option or two times meet any of auth options */
2766 if (tcp_parse_auth_options(th, &md5_location, &aoh)) {
2767 tcp_hash_fail("TCP segment has incorrect auth options set",
2768 family, skb, "");
2769 return SKB_DROP_REASON_TCP_AUTH_HDR;
2770 }
2771
2772 if (req) {
2773 if (tcp_rsk_used_ao(req) != !!aoh) {
2774 NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPAOBAD);
2775 tcp_hash_fail("TCP connection can't start/end using TCP-AO",
2776 family, skb, "%s",
2777 !aoh ? "missing AO" : "AO signed");
2778 return SKB_DROP_REASON_TCP_AOFAILURE;
2779 }
2780 }
2781
2782 /* sdif set, means packet ingressed via a device
2783 * in an L3 domain and dif is set to the l3mdev
2784 */
2785 l3index = sdif ? dif : 0;
2786
2787 /* Fast path: unsigned segments */
2788 if (likely(!md5_location && !aoh)) {
2789 /* Drop if there's TCP-MD5 or TCP-AO key with any rcvid/sndid
2790 * for the remote peer. On TCP-AO established connection
2791 * the last key is impossible to remove, so there's
2792 * always at least one current_key.
2793 */
2794 if (tcp_ao_required(sk, saddr, family, l3index, true)) {
2795 tcp_hash_fail("AO hash is required, but not found",
2796 family, skb, "L3 index %d", l3index);
2797 return SKB_DROP_REASON_TCP_AONOTFOUND;
2798 }
2799 if (unlikely(tcp_md5_do_lookup(sk, l3index, saddr, family))) {
2800 NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMD5NOTFOUND);
2801 tcp_hash_fail("MD5 Hash not found",
2802 family, skb, "L3 index %d", l3index);
2803 return SKB_DROP_REASON_TCP_MD5NOTFOUND;
2804 }
2805 return SKB_NOT_DROPPED_YET;
2806 }
2807
2808 if (aoh)
2809 return tcp_inbound_ao_hash(sk, skb, family, req, l3index, aoh);
2810
2811 return tcp_inbound_md5_hash(sk, skb, saddr, daddr, family,
2812 l3index, md5_location);
2813}
2814
2815#endif /* _TCP_H */
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
50extern struct inet_hashinfo tcp_hashinfo;
51
52extern struct percpu_counter tcp_orphan_count;
53extern 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
174/*
175 * TCP option lengths
176 */
177
178#define TCPOLEN_MSS 4
179#define TCPOLEN_WINDOW 3
180#define TCPOLEN_SACK_PERM 2
181#define TCPOLEN_TIMESTAMP 10
182#define TCPOLEN_MD5SIG 18
183#define TCPOLEN_COOKIE_BASE 2 /* Cookie-less header extension */
184#define TCPOLEN_COOKIE_PAIR 3 /* Cookie pair header extension */
185#define TCPOLEN_COOKIE_MIN (TCPOLEN_COOKIE_BASE+TCP_COOKIE_MIN)
186#define TCPOLEN_COOKIE_MAX (TCPOLEN_COOKIE_BASE+TCP_COOKIE_MAX)
187
188/* But this is what stacks really send out. */
189#define TCPOLEN_TSTAMP_ALIGNED 12
190#define TCPOLEN_WSCALE_ALIGNED 4
191#define TCPOLEN_SACKPERM_ALIGNED 4
192#define TCPOLEN_SACK_BASE 2
193#define TCPOLEN_SACK_BASE_ALIGNED 4
194#define TCPOLEN_SACK_PERBLOCK 8
195#define TCPOLEN_MD5SIG_ALIGNED 20
196#define TCPOLEN_MSS_ALIGNED 4
197
198/* Flags in tp->nonagle */
199#define TCP_NAGLE_OFF 1 /* Nagle's algo is disabled */
200#define TCP_NAGLE_CORK 2 /* Socket is corked */
201#define TCP_NAGLE_PUSH 4 /* Cork is overridden for already queued data */
202
203/* TCP thin-stream limits */
204#define TCP_THIN_LINEAR_RETRIES 6 /* After 6 linear retries, do exp. backoff */
205
206/* TCP initial congestion window as per draft-hkchu-tcpm-initcwnd-01 */
207#define TCP_INIT_CWND 10
208
209extern struct inet_timewait_death_row tcp_death_row;
210
211/* sysctl variables for tcp */
212extern int sysctl_tcp_timestamps;
213extern int sysctl_tcp_window_scaling;
214extern int sysctl_tcp_sack;
215extern int sysctl_tcp_fin_timeout;
216extern int sysctl_tcp_keepalive_time;
217extern int sysctl_tcp_keepalive_probes;
218extern int sysctl_tcp_keepalive_intvl;
219extern int sysctl_tcp_syn_retries;
220extern int sysctl_tcp_synack_retries;
221extern int sysctl_tcp_retries1;
222extern int sysctl_tcp_retries2;
223extern int sysctl_tcp_orphan_retries;
224extern int sysctl_tcp_syncookies;
225extern int sysctl_tcp_retrans_collapse;
226extern int sysctl_tcp_stdurg;
227extern int sysctl_tcp_rfc1337;
228extern int sysctl_tcp_abort_on_overflow;
229extern int sysctl_tcp_max_orphans;
230extern int sysctl_tcp_fack;
231extern int sysctl_tcp_reordering;
232extern int sysctl_tcp_ecn;
233extern int sysctl_tcp_dsack;
234extern int sysctl_tcp_wmem[3];
235extern int sysctl_tcp_rmem[3];
236extern int sysctl_tcp_app_win;
237extern int sysctl_tcp_adv_win_scale;
238extern int sysctl_tcp_tw_reuse;
239extern int sysctl_tcp_frto;
240extern int sysctl_tcp_frto_response;
241extern int sysctl_tcp_low_latency;
242extern int sysctl_tcp_dma_copybreak;
243extern int sysctl_tcp_nometrics_save;
244extern int sysctl_tcp_moderate_rcvbuf;
245extern int sysctl_tcp_tso_win_divisor;
246extern int sysctl_tcp_abc;
247extern int sysctl_tcp_mtu_probing;
248extern int sysctl_tcp_base_mss;
249extern int sysctl_tcp_workaround_signed_windows;
250extern int sysctl_tcp_slow_start_after_idle;
251extern int sysctl_tcp_max_ssthresh;
252extern int sysctl_tcp_cookie_size;
253extern int sysctl_tcp_thin_linear_timeouts;
254extern int sysctl_tcp_thin_dupack;
255extern int sysctl_tcp_early_retrans;
256
257extern atomic_long_t tcp_memory_allocated;
258extern struct percpu_counter tcp_sockets_allocated;
259extern int tcp_memory_pressure;
260
261/*
262 * The next routines deal with comparing 32 bit unsigned ints
263 * and worry about wraparound (automatic with unsigned arithmetic).
264 */
265
266static inline bool before(__u32 seq1, __u32 seq2)
267{
268 return (__s32)(seq1-seq2) < 0;
269}
270#define after(seq2, seq1) before(seq1, seq2)
271
272/* is s2<=s1<=s3 ? */
273static inline bool between(__u32 seq1, __u32 seq2, __u32 seq3)
274{
275 return seq3 - seq2 >= seq1 - seq2;
276}
277
278static inline bool tcp_out_of_memory(struct sock *sk)
279{
280 if (sk->sk_wmem_queued > SOCK_MIN_SNDBUF &&
281 sk_memory_allocated(sk) > sk_prot_mem_limits(sk, 2))
282 return true;
283 return false;
284}
285
286static inline bool tcp_too_many_orphans(struct sock *sk, int shift)
287{
288 struct percpu_counter *ocp = sk->sk_prot->orphan_count;
289 int orphans = percpu_counter_read_positive(ocp);
290
291 if (orphans << shift > sysctl_tcp_max_orphans) {
292 orphans = percpu_counter_sum_positive(ocp);
293 if (orphans << shift > sysctl_tcp_max_orphans)
294 return true;
295 }
296 return false;
297}
298
299extern bool tcp_check_oom(struct sock *sk, int shift);
300
301/* syncookies: remember time of last synqueue overflow */
302static inline void tcp_synq_overflow(struct sock *sk)
303{
304 tcp_sk(sk)->rx_opt.ts_recent_stamp = jiffies;
305}
306
307/* syncookies: no recent synqueue overflow on this listening socket? */
308static inline bool tcp_synq_no_recent_overflow(const struct sock *sk)
309{
310 unsigned long last_overflow = tcp_sk(sk)->rx_opt.ts_recent_stamp;
311 return time_after(jiffies, last_overflow + TCP_TIMEOUT_FALLBACK);
312}
313
314extern struct proto tcp_prot;
315
316#define TCP_INC_STATS(net, field) SNMP_INC_STATS((net)->mib.tcp_statistics, field)
317#define TCP_INC_STATS_BH(net, field) SNMP_INC_STATS_BH((net)->mib.tcp_statistics, field)
318#define TCP_DEC_STATS(net, field) SNMP_DEC_STATS((net)->mib.tcp_statistics, field)
319#define TCP_ADD_STATS_USER(net, field, val) SNMP_ADD_STATS_USER((net)->mib.tcp_statistics, field, val)
320#define TCP_ADD_STATS(net, field, val) SNMP_ADD_STATS((net)->mib.tcp_statistics, field, val)
321
322extern void tcp_init_mem(struct net *net);
323
324extern void tcp_v4_err(struct sk_buff *skb, u32);
325
326extern void tcp_shutdown (struct sock *sk, int how);
327
328extern int tcp_v4_rcv(struct sk_buff *skb);
329
330extern struct inet_peer *tcp_v4_get_peer(struct sock *sk, bool *release_it);
331extern void *tcp_v4_tw_get_peer(struct sock *sk);
332extern int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw);
333extern int tcp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
334 size_t size);
335extern int tcp_sendpage(struct sock *sk, struct page *page, int offset,
336 size_t size, int flags);
337extern int tcp_ioctl(struct sock *sk, int cmd, unsigned long arg);
338extern int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb,
339 const struct tcphdr *th, unsigned int len);
340extern int tcp_rcv_established(struct sock *sk, struct sk_buff *skb,
341 const struct tcphdr *th, unsigned int len);
342extern void tcp_rcv_space_adjust(struct sock *sk);
343extern void tcp_cleanup_rbuf(struct sock *sk, int copied);
344extern int tcp_twsk_unique(struct sock *sk, struct sock *sktw, void *twp);
345extern void tcp_twsk_destructor(struct sock *sk);
346extern ssize_t tcp_splice_read(struct socket *sk, loff_t *ppos,
347 struct pipe_inode_info *pipe, size_t len,
348 unsigned int flags);
349
350static inline void tcp_dec_quickack_mode(struct sock *sk,
351 const unsigned int pkts)
352{
353 struct inet_connection_sock *icsk = inet_csk(sk);
354
355 if (icsk->icsk_ack.quick) {
356 if (pkts >= icsk->icsk_ack.quick) {
357 icsk->icsk_ack.quick = 0;
358 /* Leaving quickack mode we deflate ATO. */
359 icsk->icsk_ack.ato = TCP_ATO_MIN;
360 } else
361 icsk->icsk_ack.quick -= pkts;
362 }
363}
364
365#define TCP_ECN_OK 1
366#define TCP_ECN_QUEUE_CWR 2
367#define TCP_ECN_DEMAND_CWR 4
368#define TCP_ECN_SEEN 8
369
370enum tcp_tw_status {
371 TCP_TW_SUCCESS = 0,
372 TCP_TW_RST = 1,
373 TCP_TW_ACK = 2,
374 TCP_TW_SYN = 3
375};
376
377
378extern enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw,
379 struct sk_buff *skb,
380 const struct tcphdr *th);
381extern struct sock * tcp_check_req(struct sock *sk,struct sk_buff *skb,
382 struct request_sock *req,
383 struct request_sock **prev);
384extern int tcp_child_process(struct sock *parent, struct sock *child,
385 struct sk_buff *skb);
386extern bool tcp_use_frto(struct sock *sk);
387extern void tcp_enter_frto(struct sock *sk);
388extern void tcp_enter_loss(struct sock *sk, int how);
389extern void tcp_clear_retrans(struct tcp_sock *tp);
390extern void tcp_update_metrics(struct sock *sk);
391extern void tcp_close(struct sock *sk, long timeout);
392extern void tcp_init_sock(struct sock *sk);
393extern unsigned int tcp_poll(struct file * file, struct socket *sock,
394 struct poll_table_struct *wait);
395extern int tcp_getsockopt(struct sock *sk, int level, int optname,
396 char __user *optval, int __user *optlen);
397extern int tcp_setsockopt(struct sock *sk, int level, int optname,
398 char __user *optval, unsigned int optlen);
399extern int compat_tcp_getsockopt(struct sock *sk, int level, int optname,
400 char __user *optval, int __user *optlen);
401extern int compat_tcp_setsockopt(struct sock *sk, int level, int optname,
402 char __user *optval, unsigned int optlen);
403extern void tcp_set_keepalive(struct sock *sk, int val);
404extern void tcp_syn_ack_timeout(struct sock *sk, struct request_sock *req);
405extern int tcp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
406 size_t len, int nonblock, int flags, int *addr_len);
407extern void tcp_parse_options(const struct sk_buff *skb,
408 struct tcp_options_received *opt_rx, const u8 **hvpp,
409 int estab);
410extern const u8 *tcp_parse_md5sig_option(const struct tcphdr *th);
411
412/*
413 * TCP v4 functions exported for the inet6 API
414 */
415
416extern void tcp_v4_send_check(struct sock *sk, struct sk_buff *skb);
417extern int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb);
418extern struct sock * tcp_create_openreq_child(struct sock *sk,
419 struct request_sock *req,
420 struct sk_buff *skb);
421extern struct sock * tcp_v4_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
422 struct request_sock *req,
423 struct dst_entry *dst);
424extern int tcp_v4_do_rcv(struct sock *sk, struct sk_buff *skb);
425extern int tcp_v4_connect(struct sock *sk, struct sockaddr *uaddr,
426 int addr_len);
427extern int tcp_connect(struct sock *sk);
428extern struct sk_buff * tcp_make_synack(struct sock *sk, struct dst_entry *dst,
429 struct request_sock *req,
430 struct request_values *rvp);
431extern int tcp_disconnect(struct sock *sk, int flags);
432
433void tcp_connect_init(struct sock *sk);
434void tcp_finish_connect(struct sock *sk, struct sk_buff *skb);
435int tcp_send_rcvq(struct sock *sk, struct msghdr *msg, size_t size);
436
437/* From syncookies.c */
438extern __u32 syncookie_secret[2][16-4+SHA_DIGEST_WORDS];
439extern struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
440 struct ip_options *opt);
441#ifdef CONFIG_SYN_COOKIES
442extern __u32 cookie_v4_init_sequence(struct sock *sk, struct sk_buff *skb,
443 __u16 *mss);
444#else
445static inline __u32 cookie_v4_init_sequence(struct sock *sk,
446 struct sk_buff *skb,
447 __u16 *mss)
448{
449 return 0;
450}
451#endif
452
453extern __u32 cookie_init_timestamp(struct request_sock *req);
454extern bool cookie_check_timestamp(struct tcp_options_received *opt, bool *);
455
456/* From net/ipv6/syncookies.c */
457extern struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb);
458#ifdef CONFIG_SYN_COOKIES
459extern __u32 cookie_v6_init_sequence(struct sock *sk, const struct sk_buff *skb,
460 __u16 *mss);
461#else
462static inline __u32 cookie_v6_init_sequence(struct sock *sk,
463 struct sk_buff *skb,
464 __u16 *mss)
465{
466 return 0;
467}
468#endif
469/* tcp_output.c */
470
471extern void __tcp_push_pending_frames(struct sock *sk, unsigned int cur_mss,
472 int nonagle);
473extern bool tcp_may_send_now(struct sock *sk);
474extern int tcp_retransmit_skb(struct sock *, struct sk_buff *);
475extern void tcp_retransmit_timer(struct sock *sk);
476extern void tcp_xmit_retransmit_queue(struct sock *);
477extern void tcp_simple_retransmit(struct sock *);
478extern int tcp_trim_head(struct sock *, struct sk_buff *, u32);
479extern int tcp_fragment(struct sock *, struct sk_buff *, u32, unsigned int);
480
481extern void tcp_send_probe0(struct sock *);
482extern void tcp_send_partial(struct sock *);
483extern int tcp_write_wakeup(struct sock *);
484extern void tcp_send_fin(struct sock *sk);
485extern void tcp_send_active_reset(struct sock *sk, gfp_t priority);
486extern int tcp_send_synack(struct sock *);
487extern bool tcp_syn_flood_action(struct sock *sk,
488 const struct sk_buff *skb,
489 const char *proto);
490extern void tcp_push_one(struct sock *, unsigned int mss_now);
491extern void tcp_send_ack(struct sock *sk);
492extern void tcp_send_delayed_ack(struct sock *sk);
493
494/* tcp_input.c */
495extern void tcp_cwnd_application_limited(struct sock *sk);
496extern void tcp_resume_early_retransmit(struct sock *sk);
497extern void tcp_rearm_rto(struct sock *sk);
498
499/* tcp_timer.c */
500extern void tcp_init_xmit_timers(struct sock *);
501static inline void tcp_clear_xmit_timers(struct sock *sk)
502{
503 inet_csk_clear_xmit_timers(sk);
504}
505
506extern unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu);
507extern unsigned int tcp_current_mss(struct sock *sk);
508
509/* Bound MSS / TSO packet size with the half of the window */
510static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize)
511{
512 int cutoff;
513
514 /* When peer uses tiny windows, there is no use in packetizing
515 * to sub-MSS pieces for the sake of SWS or making sure there
516 * are enough packets in the pipe for fast recovery.
517 *
518 * On the other hand, for extremely large MSS devices, handling
519 * smaller than MSS windows in this way does make sense.
520 */
521 if (tp->max_window >= 512)
522 cutoff = (tp->max_window >> 1);
523 else
524 cutoff = tp->max_window;
525
526 if (cutoff && pktsize > cutoff)
527 return max_t(int, cutoff, 68U - tp->tcp_header_len);
528 else
529 return pktsize;
530}
531
532/* tcp.c */
533extern void tcp_get_info(const struct sock *, struct tcp_info *);
534
535/* Read 'sendfile()'-style from a TCP socket */
536typedef int (*sk_read_actor_t)(read_descriptor_t *, struct sk_buff *,
537 unsigned int, size_t);
538extern int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
539 sk_read_actor_t recv_actor);
540
541extern void tcp_initialize_rcv_mss(struct sock *sk);
542
543extern int tcp_mtu_to_mss(struct sock *sk, int pmtu);
544extern int tcp_mss_to_mtu(struct sock *sk, int mss);
545extern void tcp_mtup_init(struct sock *sk);
546extern void tcp_valid_rtt_meas(struct sock *sk, u32 seq_rtt);
547
548static inline void tcp_bound_rto(const struct sock *sk)
549{
550 if (inet_csk(sk)->icsk_rto > TCP_RTO_MAX)
551 inet_csk(sk)->icsk_rto = TCP_RTO_MAX;
552}
553
554static inline u32 __tcp_set_rto(const struct tcp_sock *tp)
555{
556 return (tp->srtt >> 3) + tp->rttvar;
557}
558
559static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd)
560{
561 tp->pred_flags = htonl((tp->tcp_header_len << 26) |
562 ntohl(TCP_FLAG_ACK) |
563 snd_wnd);
564}
565
566static inline void tcp_fast_path_on(struct tcp_sock *tp)
567{
568 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale);
569}
570
571static inline void tcp_fast_path_check(struct sock *sk)
572{
573 struct tcp_sock *tp = tcp_sk(sk);
574
575 if (skb_queue_empty(&tp->out_of_order_queue) &&
576 tp->rcv_wnd &&
577 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf &&
578 !tp->urg_data)
579 tcp_fast_path_on(tp);
580}
581
582/* Compute the actual rto_min value */
583static inline u32 tcp_rto_min(struct sock *sk)
584{
585 const struct dst_entry *dst = __sk_dst_get(sk);
586 u32 rto_min = TCP_RTO_MIN;
587
588 if (dst && dst_metric_locked(dst, RTAX_RTO_MIN))
589 rto_min = dst_metric_rtt(dst, RTAX_RTO_MIN);
590 return rto_min;
591}
592
593/* Compute the actual receive window we are currently advertising.
594 * Rcv_nxt can be after the window if our peer push more data
595 * than the offered window.
596 */
597static inline u32 tcp_receive_window(const struct tcp_sock *tp)
598{
599 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt;
600
601 if (win < 0)
602 win = 0;
603 return (u32) win;
604}
605
606/* Choose a new window, without checks for shrinking, and without
607 * scaling applied to the result. The caller does these things
608 * if necessary. This is a "raw" window selection.
609 */
610extern u32 __tcp_select_window(struct sock *sk);
611
612void tcp_send_window_probe(struct sock *sk);
613
614/* TCP timestamps are only 32-bits, this causes a slight
615 * complication on 64-bit systems since we store a snapshot
616 * of jiffies in the buffer control blocks below. We decided
617 * to use only the low 32-bits of jiffies and hide the ugly
618 * casts with the following macro.
619 */
620#define tcp_time_stamp ((__u32)(jiffies))
621
622#define tcp_flag_byte(th) (((u_int8_t *)th)[13])
623
624#define TCPHDR_FIN 0x01
625#define TCPHDR_SYN 0x02
626#define TCPHDR_RST 0x04
627#define TCPHDR_PSH 0x08
628#define TCPHDR_ACK 0x10
629#define TCPHDR_URG 0x20
630#define TCPHDR_ECE 0x40
631#define TCPHDR_CWR 0x80
632
633/* This is what the send packet queuing engine uses to pass
634 * TCP per-packet control information to the transmission code.
635 * We also store the host-order sequence numbers in here too.
636 * This is 44 bytes if IPV6 is enabled.
637 * If this grows please adjust skbuff.h:skbuff->cb[xxx] size appropriately.
638 */
639struct tcp_skb_cb {
640 union {
641 struct inet_skb_parm h4;
642#if IS_ENABLED(CONFIG_IPV6)
643 struct inet6_skb_parm h6;
644#endif
645 } header; /* For incoming frames */
646 __u32 seq; /* Starting sequence number */
647 __u32 end_seq; /* SEQ + FIN + SYN + datalen */
648 __u32 when; /* used to compute rtt's */
649 __u8 tcp_flags; /* TCP header flags. (tcp[13]) */
650
651 __u8 sacked; /* State flags for SACK/FACK. */
652#define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */
653#define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */
654#define TCPCB_LOST 0x04 /* SKB is lost */
655#define TCPCB_TAGBITS 0x07 /* All tag bits */
656#define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */
657#define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS)
658
659 __u8 ip_dsfield; /* IPv4 tos or IPv6 dsfield */
660 /* 1 byte hole */
661 __u32 ack_seq; /* Sequence number ACK'd */
662};
663
664#define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0]))
665
666/* RFC3168 : 6.1.1 SYN packets must not have ECT/ECN bits set
667 *
668 * If we receive a SYN packet with these bits set, it means a network is
669 * playing bad games with TOS bits. In order to avoid possible false congestion
670 * notifications, we disable TCP ECN negociation.
671 */
672static inline void
673TCP_ECN_create_request(struct request_sock *req, const struct sk_buff *skb)
674{
675 const struct tcphdr *th = tcp_hdr(skb);
676
677 if (sysctl_tcp_ecn && th->ece && th->cwr &&
678 INET_ECN_is_not_ect(TCP_SKB_CB(skb)->ip_dsfield))
679 inet_rsk(req)->ecn_ok = 1;
680}
681
682/* Due to TSO, an SKB can be composed of multiple actual
683 * packets. To keep these tracked properly, we use this.
684 */
685static inline int tcp_skb_pcount(const struct sk_buff *skb)
686{
687 return skb_shinfo(skb)->gso_segs;
688}
689
690/* This is valid iff tcp_skb_pcount() > 1. */
691static inline int tcp_skb_mss(const struct sk_buff *skb)
692{
693 return skb_shinfo(skb)->gso_size;
694}
695
696/* Events passed to congestion control interface */
697enum tcp_ca_event {
698 CA_EVENT_TX_START, /* first transmit when no packets in flight */
699 CA_EVENT_CWND_RESTART, /* congestion window restart */
700 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */
701 CA_EVENT_FRTO, /* fast recovery timeout */
702 CA_EVENT_LOSS, /* loss timeout */
703 CA_EVENT_FAST_ACK, /* in sequence ack */
704 CA_EVENT_SLOW_ACK, /* other ack */
705};
706
707/*
708 * Interface for adding new TCP congestion control handlers
709 */
710#define TCP_CA_NAME_MAX 16
711#define TCP_CA_MAX 128
712#define TCP_CA_BUF_MAX (TCP_CA_NAME_MAX*TCP_CA_MAX)
713
714#define TCP_CONG_NON_RESTRICTED 0x1
715#define TCP_CONG_RTT_STAMP 0x2
716
717struct tcp_congestion_ops {
718 struct list_head list;
719 unsigned long flags;
720
721 /* initialize private data (optional) */
722 void (*init)(struct sock *sk);
723 /* cleanup private data (optional) */
724 void (*release)(struct sock *sk);
725
726 /* return slow start threshold (required) */
727 u32 (*ssthresh)(struct sock *sk);
728 /* lower bound for congestion window (optional) */
729 u32 (*min_cwnd)(const struct sock *sk);
730 /* do new cwnd calculation (required) */
731 void (*cong_avoid)(struct sock *sk, u32 ack, u32 in_flight);
732 /* call before changing ca_state (optional) */
733 void (*set_state)(struct sock *sk, u8 new_state);
734 /* call when cwnd event occurs (optional) */
735 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev);
736 /* new value of cwnd after loss (optional) */
737 u32 (*undo_cwnd)(struct sock *sk);
738 /* hook for packet ack accounting (optional) */
739 void (*pkts_acked)(struct sock *sk, u32 num_acked, s32 rtt_us);
740 /* get info for inet_diag (optional) */
741 void (*get_info)(struct sock *sk, u32 ext, struct sk_buff *skb);
742
743 char name[TCP_CA_NAME_MAX];
744 struct module *owner;
745};
746
747extern int tcp_register_congestion_control(struct tcp_congestion_ops *type);
748extern void tcp_unregister_congestion_control(struct tcp_congestion_ops *type);
749
750extern void tcp_init_congestion_control(struct sock *sk);
751extern void tcp_cleanup_congestion_control(struct sock *sk);
752extern int tcp_set_default_congestion_control(const char *name);
753extern void tcp_get_default_congestion_control(char *name);
754extern void tcp_get_available_congestion_control(char *buf, size_t len);
755extern void tcp_get_allowed_congestion_control(char *buf, size_t len);
756extern int tcp_set_allowed_congestion_control(char *allowed);
757extern int tcp_set_congestion_control(struct sock *sk, const char *name);
758extern void tcp_slow_start(struct tcp_sock *tp);
759extern void tcp_cong_avoid_ai(struct tcp_sock *tp, u32 w);
760
761extern struct tcp_congestion_ops tcp_init_congestion_ops;
762extern u32 tcp_reno_ssthresh(struct sock *sk);
763extern void tcp_reno_cong_avoid(struct sock *sk, u32 ack, u32 in_flight);
764extern u32 tcp_reno_min_cwnd(const struct sock *sk);
765extern struct tcp_congestion_ops tcp_reno;
766
767static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state)
768{
769 struct inet_connection_sock *icsk = inet_csk(sk);
770
771 if (icsk->icsk_ca_ops->set_state)
772 icsk->icsk_ca_ops->set_state(sk, ca_state);
773 icsk->icsk_ca_state = ca_state;
774}
775
776static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event)
777{
778 const struct inet_connection_sock *icsk = inet_csk(sk);
779
780 if (icsk->icsk_ca_ops->cwnd_event)
781 icsk->icsk_ca_ops->cwnd_event(sk, event);
782}
783
784/* These functions determine how the current flow behaves in respect of SACK
785 * handling. SACK is negotiated with the peer, and therefore it can vary
786 * between different flows.
787 *
788 * tcp_is_sack - SACK enabled
789 * tcp_is_reno - No SACK
790 * tcp_is_fack - FACK enabled, implies SACK enabled
791 */
792static inline int tcp_is_sack(const struct tcp_sock *tp)
793{
794 return tp->rx_opt.sack_ok;
795}
796
797static inline bool tcp_is_reno(const struct tcp_sock *tp)
798{
799 return !tcp_is_sack(tp);
800}
801
802static inline bool tcp_is_fack(const struct tcp_sock *tp)
803{
804 return tp->rx_opt.sack_ok & TCP_FACK_ENABLED;
805}
806
807static inline void tcp_enable_fack(struct tcp_sock *tp)
808{
809 tp->rx_opt.sack_ok |= TCP_FACK_ENABLED;
810}
811
812/* TCP early-retransmit (ER) is similar to but more conservative than
813 * the thin-dupack feature. Enable ER only if thin-dupack is disabled.
814 */
815static inline void tcp_enable_early_retrans(struct tcp_sock *tp)
816{
817 tp->do_early_retrans = sysctl_tcp_early_retrans &&
818 !sysctl_tcp_thin_dupack && sysctl_tcp_reordering == 3;
819 tp->early_retrans_delayed = 0;
820}
821
822static inline void tcp_disable_early_retrans(struct tcp_sock *tp)
823{
824 tp->do_early_retrans = 0;
825}
826
827static inline unsigned int tcp_left_out(const struct tcp_sock *tp)
828{
829 return tp->sacked_out + tp->lost_out;
830}
831
832/* This determines how many packets are "in the network" to the best
833 * of our knowledge. In many cases it is conservative, but where
834 * detailed information is available from the receiver (via SACK
835 * blocks etc.) we can make more aggressive calculations.
836 *
837 * Use this for decisions involving congestion control, use just
838 * tp->packets_out to determine if the send queue is empty or not.
839 *
840 * Read this equation as:
841 *
842 * "Packets sent once on transmission queue" MINUS
843 * "Packets left network, but not honestly ACKed yet" PLUS
844 * "Packets fast retransmitted"
845 */
846static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp)
847{
848 return tp->packets_out - tcp_left_out(tp) + tp->retrans_out;
849}
850
851#define TCP_INFINITE_SSTHRESH 0x7fffffff
852
853static inline bool tcp_in_initial_slowstart(const struct tcp_sock *tp)
854{
855 return tp->snd_ssthresh >= TCP_INFINITE_SSTHRESH;
856}
857
858/* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd.
859 * The exception is rate halving phase, when cwnd is decreasing towards
860 * ssthresh.
861 */
862static inline __u32 tcp_current_ssthresh(const struct sock *sk)
863{
864 const struct tcp_sock *tp = tcp_sk(sk);
865
866 if ((1 << inet_csk(sk)->icsk_ca_state) & (TCPF_CA_CWR | TCPF_CA_Recovery))
867 return tp->snd_ssthresh;
868 else
869 return max(tp->snd_ssthresh,
870 ((tp->snd_cwnd >> 1) +
871 (tp->snd_cwnd >> 2)));
872}
873
874/* Use define here intentionally to get WARN_ON location shown at the caller */
875#define tcp_verify_left_out(tp) WARN_ON(tcp_left_out(tp) > tp->packets_out)
876
877extern void tcp_enter_cwr(struct sock *sk, const int set_ssthresh);
878extern __u32 tcp_init_cwnd(const struct tcp_sock *tp, const struct dst_entry *dst);
879
880/* The maximum number of MSS of available cwnd for which TSO defers
881 * sending if not using sysctl_tcp_tso_win_divisor.
882 */
883static inline __u32 tcp_max_tso_deferred_mss(const struct tcp_sock *tp)
884{
885 return 3;
886}
887
888/* Slow start with delack produces 3 packets of burst, so that
889 * it is safe "de facto". This will be the default - same as
890 * the default reordering threshold - but if reordering increases,
891 * we must be able to allow cwnd to burst at least this much in order
892 * to not pull it back when holes are filled.
893 */
894static __inline__ __u32 tcp_max_burst(const struct tcp_sock *tp)
895{
896 return tp->reordering;
897}
898
899/* Returns end sequence number of the receiver's advertised window */
900static inline u32 tcp_wnd_end(const struct tcp_sock *tp)
901{
902 return tp->snd_una + tp->snd_wnd;
903}
904extern bool tcp_is_cwnd_limited(const struct sock *sk, u32 in_flight);
905
906static inline void tcp_minshall_update(struct tcp_sock *tp, unsigned int mss,
907 const struct sk_buff *skb)
908{
909 if (skb->len < mss)
910 tp->snd_sml = TCP_SKB_CB(skb)->end_seq;
911}
912
913static inline void tcp_check_probe_timer(struct sock *sk)
914{
915 const struct tcp_sock *tp = tcp_sk(sk);
916 const struct inet_connection_sock *icsk = inet_csk(sk);
917
918 if (!tp->packets_out && !icsk->icsk_pending)
919 inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
920 icsk->icsk_rto, TCP_RTO_MAX);
921}
922
923static inline void tcp_init_wl(struct tcp_sock *tp, u32 seq)
924{
925 tp->snd_wl1 = seq;
926}
927
928static inline void tcp_update_wl(struct tcp_sock *tp, u32 seq)
929{
930 tp->snd_wl1 = seq;
931}
932
933/*
934 * Calculate(/check) TCP checksum
935 */
936static inline __sum16 tcp_v4_check(int len, __be32 saddr,
937 __be32 daddr, __wsum base)
938{
939 return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base);
940}
941
942static inline __sum16 __tcp_checksum_complete(struct sk_buff *skb)
943{
944 return __skb_checksum_complete(skb);
945}
946
947static inline bool tcp_checksum_complete(struct sk_buff *skb)
948{
949 return !skb_csum_unnecessary(skb) &&
950 __tcp_checksum_complete(skb);
951}
952
953/* Prequeue for VJ style copy to user, combined with checksumming. */
954
955static inline void tcp_prequeue_init(struct tcp_sock *tp)
956{
957 tp->ucopy.task = NULL;
958 tp->ucopy.len = 0;
959 tp->ucopy.memory = 0;
960 skb_queue_head_init(&tp->ucopy.prequeue);
961#ifdef CONFIG_NET_DMA
962 tp->ucopy.dma_chan = NULL;
963 tp->ucopy.wakeup = 0;
964 tp->ucopy.pinned_list = NULL;
965 tp->ucopy.dma_cookie = 0;
966#endif
967}
968
969/* Packet is added to VJ-style prequeue for processing in process
970 * context, if a reader task is waiting. Apparently, this exciting
971 * idea (VJ's mail "Re: query about TCP header on tcp-ip" of 07 Sep 93)
972 * failed somewhere. Latency? Burstiness? Well, at least now we will
973 * see, why it failed. 8)8) --ANK
974 *
975 * NOTE: is this not too big to inline?
976 */
977static inline bool tcp_prequeue(struct sock *sk, struct sk_buff *skb)
978{
979 struct tcp_sock *tp = tcp_sk(sk);
980
981 if (sysctl_tcp_low_latency || !tp->ucopy.task)
982 return false;
983
984 __skb_queue_tail(&tp->ucopy.prequeue, skb);
985 tp->ucopy.memory += skb->truesize;
986 if (tp->ucopy.memory > sk->sk_rcvbuf) {
987 struct sk_buff *skb1;
988
989 BUG_ON(sock_owned_by_user(sk));
990
991 while ((skb1 = __skb_dequeue(&tp->ucopy.prequeue)) != NULL) {
992 sk_backlog_rcv(sk, skb1);
993 NET_INC_STATS_BH(sock_net(sk),
994 LINUX_MIB_TCPPREQUEUEDROPPED);
995 }
996
997 tp->ucopy.memory = 0;
998 } else if (skb_queue_len(&tp->ucopy.prequeue) == 1) {
999 wake_up_interruptible_sync_poll(sk_sleep(sk),
1000 POLLIN | POLLRDNORM | POLLRDBAND);
1001 if (!inet_csk_ack_scheduled(sk))
1002 inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
1003 (3 * tcp_rto_min(sk)) / 4,
1004 TCP_RTO_MAX);
1005 }
1006 return true;
1007}
1008
1009
1010#undef STATE_TRACE
1011
1012#ifdef STATE_TRACE
1013static const char *statename[]={
1014 "Unused","Established","Syn Sent","Syn Recv",
1015 "Fin Wait 1","Fin Wait 2","Time Wait", "Close",
1016 "Close Wait","Last ACK","Listen","Closing"
1017};
1018#endif
1019extern void tcp_set_state(struct sock *sk, int state);
1020
1021extern void tcp_done(struct sock *sk);
1022
1023static inline void tcp_sack_reset(struct tcp_options_received *rx_opt)
1024{
1025 rx_opt->dsack = 0;
1026 rx_opt->num_sacks = 0;
1027}
1028
1029/* Determine a window scaling and initial window to offer. */
1030extern void tcp_select_initial_window(int __space, __u32 mss,
1031 __u32 *rcv_wnd, __u32 *window_clamp,
1032 int wscale_ok, __u8 *rcv_wscale,
1033 __u32 init_rcv_wnd);
1034
1035static inline int tcp_win_from_space(int space)
1036{
1037 return sysctl_tcp_adv_win_scale<=0 ?
1038 (space>>(-sysctl_tcp_adv_win_scale)) :
1039 space - (space>>sysctl_tcp_adv_win_scale);
1040}
1041
1042/* Note: caller must be prepared to deal with negative returns */
1043static inline int tcp_space(const struct sock *sk)
1044{
1045 return tcp_win_from_space(sk->sk_rcvbuf -
1046 atomic_read(&sk->sk_rmem_alloc));
1047}
1048
1049static inline int tcp_full_space(const struct sock *sk)
1050{
1051 return tcp_win_from_space(sk->sk_rcvbuf);
1052}
1053
1054static inline void tcp_openreq_init(struct request_sock *req,
1055 struct tcp_options_received *rx_opt,
1056 struct sk_buff *skb)
1057{
1058 struct inet_request_sock *ireq = inet_rsk(req);
1059
1060 req->rcv_wnd = 0; /* So that tcp_send_synack() knows! */
1061 req->cookie_ts = 0;
1062 tcp_rsk(req)->rcv_isn = TCP_SKB_CB(skb)->seq;
1063 req->mss = rx_opt->mss_clamp;
1064 req->ts_recent = rx_opt->saw_tstamp ? rx_opt->rcv_tsval : 0;
1065 ireq->tstamp_ok = rx_opt->tstamp_ok;
1066 ireq->sack_ok = rx_opt->sack_ok;
1067 ireq->snd_wscale = rx_opt->snd_wscale;
1068 ireq->wscale_ok = rx_opt->wscale_ok;
1069 ireq->acked = 0;
1070 ireq->ecn_ok = 0;
1071 ireq->rmt_port = tcp_hdr(skb)->source;
1072 ireq->loc_port = tcp_hdr(skb)->dest;
1073}
1074
1075extern void tcp_enter_memory_pressure(struct sock *sk);
1076
1077static inline int keepalive_intvl_when(const struct tcp_sock *tp)
1078{
1079 return tp->keepalive_intvl ? : sysctl_tcp_keepalive_intvl;
1080}
1081
1082static inline int keepalive_time_when(const struct tcp_sock *tp)
1083{
1084 return tp->keepalive_time ? : sysctl_tcp_keepalive_time;
1085}
1086
1087static inline int keepalive_probes(const struct tcp_sock *tp)
1088{
1089 return tp->keepalive_probes ? : sysctl_tcp_keepalive_probes;
1090}
1091
1092static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp)
1093{
1094 const struct inet_connection_sock *icsk = &tp->inet_conn;
1095
1096 return min_t(u32, tcp_time_stamp - icsk->icsk_ack.lrcvtime,
1097 tcp_time_stamp - tp->rcv_tstamp);
1098}
1099
1100static inline int tcp_fin_time(const struct sock *sk)
1101{
1102 int fin_timeout = tcp_sk(sk)->linger2 ? : sysctl_tcp_fin_timeout;
1103 const int rto = inet_csk(sk)->icsk_rto;
1104
1105 if (fin_timeout < (rto << 2) - (rto >> 1))
1106 fin_timeout = (rto << 2) - (rto >> 1);
1107
1108 return fin_timeout;
1109}
1110
1111static inline bool tcp_paws_check(const struct tcp_options_received *rx_opt,
1112 int paws_win)
1113{
1114 if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win)
1115 return true;
1116 if (unlikely(get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS))
1117 return true;
1118 /*
1119 * Some OSes send SYN and SYNACK messages with tsval=0 tsecr=0,
1120 * then following tcp messages have valid values. Ignore 0 value,
1121 * or else 'negative' tsval might forbid us to accept their packets.
1122 */
1123 if (!rx_opt->ts_recent)
1124 return true;
1125 return false;
1126}
1127
1128static inline bool tcp_paws_reject(const struct tcp_options_received *rx_opt,
1129 int rst)
1130{
1131 if (tcp_paws_check(rx_opt, 0))
1132 return false;
1133
1134 /* RST segments are not recommended to carry timestamp,
1135 and, if they do, it is recommended to ignore PAWS because
1136 "their cleanup function should take precedence over timestamps."
1137 Certainly, it is mistake. It is necessary to understand the reasons
1138 of this constraint to relax it: if peer reboots, clock may go
1139 out-of-sync and half-open connections will not be reset.
1140 Actually, the problem would be not existing if all
1141 the implementations followed draft about maintaining clock
1142 via reboots. Linux-2.2 DOES NOT!
1143
1144 However, we can relax time bounds for RST segments to MSL.
1145 */
1146 if (rst && get_seconds() >= rx_opt->ts_recent_stamp + TCP_PAWS_MSL)
1147 return false;
1148 return true;
1149}
1150
1151static inline void tcp_mib_init(struct net *net)
1152{
1153 /* See RFC 2012 */
1154 TCP_ADD_STATS_USER(net, TCP_MIB_RTOALGORITHM, 1);
1155 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ);
1156 TCP_ADD_STATS_USER(net, TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ);
1157 TCP_ADD_STATS_USER(net, TCP_MIB_MAXCONN, -1);
1158}
1159
1160/* from STCP */
1161static inline void tcp_clear_retrans_hints_partial(struct tcp_sock *tp)
1162{
1163 tp->lost_skb_hint = NULL;
1164 tp->scoreboard_skb_hint = NULL;
1165}
1166
1167static inline void tcp_clear_all_retrans_hints(struct tcp_sock *tp)
1168{
1169 tcp_clear_retrans_hints_partial(tp);
1170 tp->retransmit_skb_hint = NULL;
1171}
1172
1173/* MD5 Signature */
1174struct crypto_hash;
1175
1176union tcp_md5_addr {
1177 struct in_addr a4;
1178#if IS_ENABLED(CONFIG_IPV6)
1179 struct in6_addr a6;
1180#endif
1181};
1182
1183/* - key database */
1184struct tcp_md5sig_key {
1185 struct hlist_node node;
1186 u8 keylen;
1187 u8 family; /* AF_INET or AF_INET6 */
1188 union tcp_md5_addr addr;
1189 u8 key[TCP_MD5SIG_MAXKEYLEN];
1190 struct rcu_head rcu;
1191};
1192
1193/* - sock block */
1194struct tcp_md5sig_info {
1195 struct hlist_head head;
1196 struct rcu_head rcu;
1197};
1198
1199/* - pseudo header */
1200struct tcp4_pseudohdr {
1201 __be32 saddr;
1202 __be32 daddr;
1203 __u8 pad;
1204 __u8 protocol;
1205 __be16 len;
1206};
1207
1208struct tcp6_pseudohdr {
1209 struct in6_addr saddr;
1210 struct in6_addr daddr;
1211 __be32 len;
1212 __be32 protocol; /* including padding */
1213};
1214
1215union tcp_md5sum_block {
1216 struct tcp4_pseudohdr ip4;
1217#if IS_ENABLED(CONFIG_IPV6)
1218 struct tcp6_pseudohdr ip6;
1219#endif
1220};
1221
1222/* - pool: digest algorithm, hash description and scratch buffer */
1223struct tcp_md5sig_pool {
1224 struct hash_desc md5_desc;
1225 union tcp_md5sum_block md5_blk;
1226};
1227
1228/* - functions */
1229extern int tcp_v4_md5_hash_skb(char *md5_hash, struct tcp_md5sig_key *key,
1230 const struct sock *sk,
1231 const struct request_sock *req,
1232 const struct sk_buff *skb);
1233extern int tcp_md5_do_add(struct sock *sk, const union tcp_md5_addr *addr,
1234 int family, const u8 *newkey,
1235 u8 newkeylen, gfp_t gfp);
1236extern int tcp_md5_do_del(struct sock *sk, const union tcp_md5_addr *addr,
1237 int family);
1238extern struct tcp_md5sig_key *tcp_v4_md5_lookup(struct sock *sk,
1239 struct sock *addr_sk);
1240
1241#ifdef CONFIG_TCP_MD5SIG
1242extern struct tcp_md5sig_key *tcp_md5_do_lookup(struct sock *sk,
1243 const union tcp_md5_addr *addr, int family);
1244#define tcp_twsk_md5_key(twsk) ((twsk)->tw_md5_key)
1245#else
1246static inline struct tcp_md5sig_key *tcp_md5_do_lookup(struct sock *sk,
1247 const union tcp_md5_addr *addr,
1248 int family)
1249{
1250 return NULL;
1251}
1252#define tcp_twsk_md5_key(twsk) NULL
1253#endif
1254
1255extern struct tcp_md5sig_pool __percpu *tcp_alloc_md5sig_pool(struct sock *);
1256extern void tcp_free_md5sig_pool(void);
1257
1258extern struct tcp_md5sig_pool *tcp_get_md5sig_pool(void);
1259extern void tcp_put_md5sig_pool(void);
1260
1261extern int tcp_md5_hash_header(struct tcp_md5sig_pool *, const struct tcphdr *);
1262extern int tcp_md5_hash_skb_data(struct tcp_md5sig_pool *, const struct sk_buff *,
1263 unsigned int header_len);
1264extern int tcp_md5_hash_key(struct tcp_md5sig_pool *hp,
1265 const struct tcp_md5sig_key *key);
1266
1267/* write queue abstraction */
1268static inline void tcp_write_queue_purge(struct sock *sk)
1269{
1270 struct sk_buff *skb;
1271
1272 while ((skb = __skb_dequeue(&sk->sk_write_queue)) != NULL)
1273 sk_wmem_free_skb(sk, skb);
1274 sk_mem_reclaim(sk);
1275 tcp_clear_all_retrans_hints(tcp_sk(sk));
1276}
1277
1278static inline struct sk_buff *tcp_write_queue_head(const struct sock *sk)
1279{
1280 return skb_peek(&sk->sk_write_queue);
1281}
1282
1283static inline struct sk_buff *tcp_write_queue_tail(const struct sock *sk)
1284{
1285 return skb_peek_tail(&sk->sk_write_queue);
1286}
1287
1288static inline struct sk_buff *tcp_write_queue_next(const struct sock *sk,
1289 const struct sk_buff *skb)
1290{
1291 return skb_queue_next(&sk->sk_write_queue, skb);
1292}
1293
1294static inline struct sk_buff *tcp_write_queue_prev(const struct sock *sk,
1295 const struct sk_buff *skb)
1296{
1297 return skb_queue_prev(&sk->sk_write_queue, skb);
1298}
1299
1300#define tcp_for_write_queue(skb, sk) \
1301 skb_queue_walk(&(sk)->sk_write_queue, skb)
1302
1303#define tcp_for_write_queue_from(skb, sk) \
1304 skb_queue_walk_from(&(sk)->sk_write_queue, skb)
1305
1306#define tcp_for_write_queue_from_safe(skb, tmp, sk) \
1307 skb_queue_walk_from_safe(&(sk)->sk_write_queue, skb, tmp)
1308
1309static inline struct sk_buff *tcp_send_head(const struct sock *sk)
1310{
1311 return sk->sk_send_head;
1312}
1313
1314static inline bool tcp_skb_is_last(const struct sock *sk,
1315 const struct sk_buff *skb)
1316{
1317 return skb_queue_is_last(&sk->sk_write_queue, skb);
1318}
1319
1320static inline void tcp_advance_send_head(struct sock *sk, const struct sk_buff *skb)
1321{
1322 if (tcp_skb_is_last(sk, skb))
1323 sk->sk_send_head = NULL;
1324 else
1325 sk->sk_send_head = tcp_write_queue_next(sk, skb);
1326}
1327
1328static inline void tcp_check_send_head(struct sock *sk, struct sk_buff *skb_unlinked)
1329{
1330 if (sk->sk_send_head == skb_unlinked)
1331 sk->sk_send_head = NULL;
1332}
1333
1334static inline void tcp_init_send_head(struct sock *sk)
1335{
1336 sk->sk_send_head = NULL;
1337}
1338
1339static inline void __tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1340{
1341 __skb_queue_tail(&sk->sk_write_queue, skb);
1342}
1343
1344static inline void tcp_add_write_queue_tail(struct sock *sk, struct sk_buff *skb)
1345{
1346 __tcp_add_write_queue_tail(sk, skb);
1347
1348 /* Queue it, remembering where we must start sending. */
1349 if (sk->sk_send_head == NULL) {
1350 sk->sk_send_head = skb;
1351
1352 if (tcp_sk(sk)->highest_sack == NULL)
1353 tcp_sk(sk)->highest_sack = skb;
1354 }
1355}
1356
1357static inline void __tcp_add_write_queue_head(struct sock *sk, struct sk_buff *skb)
1358{
1359 __skb_queue_head(&sk->sk_write_queue, skb);
1360}
1361
1362/* Insert buff after skb on the write queue of sk. */
1363static inline void tcp_insert_write_queue_after(struct sk_buff *skb,
1364 struct sk_buff *buff,
1365 struct sock *sk)
1366{
1367 __skb_queue_after(&sk->sk_write_queue, skb, buff);
1368}
1369
1370/* Insert new before skb on the write queue of sk. */
1371static inline void tcp_insert_write_queue_before(struct sk_buff *new,
1372 struct sk_buff *skb,
1373 struct sock *sk)
1374{
1375 __skb_queue_before(&sk->sk_write_queue, skb, new);
1376
1377 if (sk->sk_send_head == skb)
1378 sk->sk_send_head = new;
1379}
1380
1381static inline void tcp_unlink_write_queue(struct sk_buff *skb, struct sock *sk)
1382{
1383 __skb_unlink(skb, &sk->sk_write_queue);
1384}
1385
1386static inline bool tcp_write_queue_empty(struct sock *sk)
1387{
1388 return skb_queue_empty(&sk->sk_write_queue);
1389}
1390
1391static inline void tcp_push_pending_frames(struct sock *sk)
1392{
1393 if (tcp_send_head(sk)) {
1394 struct tcp_sock *tp = tcp_sk(sk);
1395
1396 __tcp_push_pending_frames(sk, tcp_current_mss(sk), tp->nonagle);
1397 }
1398}
1399
1400/* Start sequence of the skb just after the highest skb with SACKed
1401 * bit, valid only if sacked_out > 0 or when the caller has ensured
1402 * validity by itself.
1403 */
1404static inline u32 tcp_highest_sack_seq(struct tcp_sock *tp)
1405{
1406 if (!tp->sacked_out)
1407 return tp->snd_una;
1408
1409 if (tp->highest_sack == NULL)
1410 return tp->snd_nxt;
1411
1412 return TCP_SKB_CB(tp->highest_sack)->seq;
1413}
1414
1415static inline void tcp_advance_highest_sack(struct sock *sk, struct sk_buff *skb)
1416{
1417 tcp_sk(sk)->highest_sack = tcp_skb_is_last(sk, skb) ? NULL :
1418 tcp_write_queue_next(sk, skb);
1419}
1420
1421static inline struct sk_buff *tcp_highest_sack(struct sock *sk)
1422{
1423 return tcp_sk(sk)->highest_sack;
1424}
1425
1426static inline void tcp_highest_sack_reset(struct sock *sk)
1427{
1428 tcp_sk(sk)->highest_sack = tcp_write_queue_head(sk);
1429}
1430
1431/* Called when old skb is about to be deleted (to be combined with new skb) */
1432static inline void tcp_highest_sack_combine(struct sock *sk,
1433 struct sk_buff *old,
1434 struct sk_buff *new)
1435{
1436 if (tcp_sk(sk)->sacked_out && (old == tcp_sk(sk)->highest_sack))
1437 tcp_sk(sk)->highest_sack = new;
1438}
1439
1440/* Determines whether this is a thin stream (which may suffer from
1441 * increased latency). Used to trigger latency-reducing mechanisms.
1442 */
1443static inline bool tcp_stream_is_thin(struct tcp_sock *tp)
1444{
1445 return tp->packets_out < 4 && !tcp_in_initial_slowstart(tp);
1446}
1447
1448/* /proc */
1449enum tcp_seq_states {
1450 TCP_SEQ_STATE_LISTENING,
1451 TCP_SEQ_STATE_OPENREQ,
1452 TCP_SEQ_STATE_ESTABLISHED,
1453 TCP_SEQ_STATE_TIME_WAIT,
1454};
1455
1456int tcp_seq_open(struct inode *inode, struct file *file);
1457
1458struct tcp_seq_afinfo {
1459 char *name;
1460 sa_family_t family;
1461 const struct file_operations *seq_fops;
1462 struct seq_operations seq_ops;
1463};
1464
1465struct tcp_iter_state {
1466 struct seq_net_private p;
1467 sa_family_t family;
1468 enum tcp_seq_states state;
1469 struct sock *syn_wait_sk;
1470 int bucket, offset, sbucket, num, uid;
1471 loff_t last_pos;
1472};
1473
1474extern int tcp_proc_register(struct net *net, struct tcp_seq_afinfo *afinfo);
1475extern void tcp_proc_unregister(struct net *net, struct tcp_seq_afinfo *afinfo);
1476
1477extern struct request_sock_ops tcp_request_sock_ops;
1478extern struct request_sock_ops tcp6_request_sock_ops;
1479
1480extern void tcp_v4_destroy_sock(struct sock *sk);
1481
1482extern int tcp_v4_gso_send_check(struct sk_buff *skb);
1483extern struct sk_buff *tcp_tso_segment(struct sk_buff *skb,
1484 netdev_features_t features);
1485extern struct sk_buff **tcp_gro_receive(struct sk_buff **head,
1486 struct sk_buff *skb);
1487extern struct sk_buff **tcp4_gro_receive(struct sk_buff **head,
1488 struct sk_buff *skb);
1489extern int tcp_gro_complete(struct sk_buff *skb);
1490extern int tcp4_gro_complete(struct sk_buff *skb);
1491
1492#ifdef CONFIG_PROC_FS
1493extern int tcp4_proc_init(void);
1494extern void tcp4_proc_exit(void);
1495#endif
1496
1497/* TCP af-specific functions */
1498struct tcp_sock_af_ops {
1499#ifdef CONFIG_TCP_MD5SIG
1500 struct tcp_md5sig_key *(*md5_lookup) (struct sock *sk,
1501 struct sock *addr_sk);
1502 int (*calc_md5_hash) (char *location,
1503 struct tcp_md5sig_key *md5,
1504 const struct sock *sk,
1505 const struct request_sock *req,
1506 const struct sk_buff *skb);
1507 int (*md5_parse) (struct sock *sk,
1508 char __user *optval,
1509 int optlen);
1510#endif
1511};
1512
1513struct tcp_request_sock_ops {
1514#ifdef CONFIG_TCP_MD5SIG
1515 struct tcp_md5sig_key *(*md5_lookup) (struct sock *sk,
1516 struct request_sock *req);
1517 int (*calc_md5_hash) (char *location,
1518 struct tcp_md5sig_key *md5,
1519 const struct sock *sk,
1520 const struct request_sock *req,
1521 const struct sk_buff *skb);
1522#endif
1523};
1524
1525/* Using SHA1 for now, define some constants.
1526 */
1527#define COOKIE_DIGEST_WORDS (SHA_DIGEST_WORDS)
1528#define COOKIE_MESSAGE_WORDS (SHA_MESSAGE_BYTES / 4)
1529#define COOKIE_WORKSPACE_WORDS (COOKIE_DIGEST_WORDS + COOKIE_MESSAGE_WORDS)
1530
1531extern int tcp_cookie_generator(u32 *bakery);
1532
1533/**
1534 * struct tcp_cookie_values - each socket needs extra space for the
1535 * cookies, together with (optional) space for any SYN data.
1536 *
1537 * A tcp_sock contains a pointer to the current value, and this is
1538 * cloned to the tcp_timewait_sock.
1539 *
1540 * @cookie_pair: variable data from the option exchange.
1541 *
1542 * @cookie_desired: user specified tcpct_cookie_desired. Zero
1543 * indicates default (sysctl_tcp_cookie_size).
1544 * After cookie sent, remembers size of cookie.
1545 * Range 0, TCP_COOKIE_MIN to TCP_COOKIE_MAX.
1546 *
1547 * @s_data_desired: user specified tcpct_s_data_desired. When the
1548 * constant payload is specified (@s_data_constant),
1549 * holds its length instead.
1550 * Range 0 to TCP_MSS_DESIRED.
1551 *
1552 * @s_data_payload: constant data that is to be included in the
1553 * payload of SYN or SYNACK segments when the
1554 * cookie option is present.
1555 */
1556struct tcp_cookie_values {
1557 struct kref kref;
1558 u8 cookie_pair[TCP_COOKIE_PAIR_SIZE];
1559 u8 cookie_pair_size;
1560 u8 cookie_desired;
1561 u16 s_data_desired:11,
1562 s_data_constant:1,
1563 s_data_in:1,
1564 s_data_out:1,
1565 s_data_unused:2;
1566 u8 s_data_payload[0];
1567};
1568
1569static inline void tcp_cookie_values_release(struct kref *kref)
1570{
1571 kfree(container_of(kref, struct tcp_cookie_values, kref));
1572}
1573
1574/* The length of constant payload data. Note that s_data_desired is
1575 * overloaded, depending on s_data_constant: either the length of constant
1576 * data (returned here) or the limit on variable data.
1577 */
1578static inline int tcp_s_data_size(const struct tcp_sock *tp)
1579{
1580 return (tp->cookie_values != NULL && tp->cookie_values->s_data_constant)
1581 ? tp->cookie_values->s_data_desired
1582 : 0;
1583}
1584
1585/**
1586 * struct tcp_extend_values - tcp_ipv?.c to tcp_output.c workspace.
1587 *
1588 * As tcp_request_sock has already been extended in other places, the
1589 * only remaining method is to pass stack values along as function
1590 * parameters. These parameters are not needed after sending SYNACK.
1591 *
1592 * @cookie_bakery: cryptographic secret and message workspace.
1593 *
1594 * @cookie_plus: bytes in authenticator/cookie option, copied from
1595 * struct tcp_options_received (above).
1596 */
1597struct tcp_extend_values {
1598 struct request_values rv;
1599 u32 cookie_bakery[COOKIE_WORKSPACE_WORDS];
1600 u8 cookie_plus:6,
1601 cookie_out_never:1,
1602 cookie_in_always:1;
1603};
1604
1605static inline struct tcp_extend_values *tcp_xv(struct request_values *rvp)
1606{
1607 return (struct tcp_extend_values *)rvp;
1608}
1609
1610extern void tcp_v4_init(void);
1611extern void tcp_init(void);
1612
1613#endif /* _TCP_H */