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 * Support for INET connection oriented protocols.
7 *
8 * Authors: See the TCP sources
9 *
10 * This program is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU General Public License
12 * as published by the Free Software Foundation; either version
13 * 2 of the License, or(at your option) any later version.
14 */
15
16#include <linux/module.h>
17#include <linux/jhash.h>
18
19#include <net/inet_connection_sock.h>
20#include <net/inet_hashtables.h>
21#include <net/inet_timewait_sock.h>
22#include <net/ip.h>
23#include <net/route.h>
24#include <net/tcp_states.h>
25#include <net/xfrm.h>
26#include <net/tcp.h>
27#include <net/sock_reuseport.h>
28#include <net/addrconf.h>
29
30#if IS_ENABLED(CONFIG_IPV6)
31/* match_wildcard == true: IPV6_ADDR_ANY equals to any IPv6 addresses if IPv6
32 * only, and any IPv4 addresses if not IPv6 only
33 * match_wildcard == false: addresses must be exactly the same, i.e.
34 * IPV6_ADDR_ANY only equals to IPV6_ADDR_ANY,
35 * and 0.0.0.0 equals to 0.0.0.0 only
36 */
37static bool ipv6_rcv_saddr_equal(const struct in6_addr *sk1_rcv_saddr6,
38 const struct in6_addr *sk2_rcv_saddr6,
39 __be32 sk1_rcv_saddr, __be32 sk2_rcv_saddr,
40 bool sk1_ipv6only, bool sk2_ipv6only,
41 bool match_wildcard)
42{
43 int addr_type = ipv6_addr_type(sk1_rcv_saddr6);
44 int addr_type2 = sk2_rcv_saddr6 ? ipv6_addr_type(sk2_rcv_saddr6) : IPV6_ADDR_MAPPED;
45
46 /* if both are mapped, treat as IPv4 */
47 if (addr_type == IPV6_ADDR_MAPPED && addr_type2 == IPV6_ADDR_MAPPED) {
48 if (!sk2_ipv6only) {
49 if (sk1_rcv_saddr == sk2_rcv_saddr)
50 return true;
51 if (!sk1_rcv_saddr || !sk2_rcv_saddr)
52 return match_wildcard;
53 }
54 return false;
55 }
56
57 if (addr_type == IPV6_ADDR_ANY && addr_type2 == IPV6_ADDR_ANY)
58 return true;
59
60 if (addr_type2 == IPV6_ADDR_ANY && match_wildcard &&
61 !(sk2_ipv6only && addr_type == IPV6_ADDR_MAPPED))
62 return true;
63
64 if (addr_type == IPV6_ADDR_ANY && match_wildcard &&
65 !(sk1_ipv6only && addr_type2 == IPV6_ADDR_MAPPED))
66 return true;
67
68 if (sk2_rcv_saddr6 &&
69 ipv6_addr_equal(sk1_rcv_saddr6, sk2_rcv_saddr6))
70 return true;
71
72 return false;
73}
74#endif
75
76/* match_wildcard == true: 0.0.0.0 equals to any IPv4 addresses
77 * match_wildcard == false: addresses must be exactly the same, i.e.
78 * 0.0.0.0 only equals to 0.0.0.0
79 */
80static bool ipv4_rcv_saddr_equal(__be32 sk1_rcv_saddr, __be32 sk2_rcv_saddr,
81 bool sk2_ipv6only, bool match_wildcard)
82{
83 if (!sk2_ipv6only) {
84 if (sk1_rcv_saddr == sk2_rcv_saddr)
85 return true;
86 if (!sk1_rcv_saddr || !sk2_rcv_saddr)
87 return match_wildcard;
88 }
89 return false;
90}
91
92bool inet_rcv_saddr_equal(const struct sock *sk, const struct sock *sk2,
93 bool match_wildcard)
94{
95#if IS_ENABLED(CONFIG_IPV6)
96 if (sk->sk_family == AF_INET6)
97 return ipv6_rcv_saddr_equal(&sk->sk_v6_rcv_saddr,
98 inet6_rcv_saddr(sk2),
99 sk->sk_rcv_saddr,
100 sk2->sk_rcv_saddr,
101 ipv6_only_sock(sk),
102 ipv6_only_sock(sk2),
103 match_wildcard);
104#endif
105 return ipv4_rcv_saddr_equal(sk->sk_rcv_saddr, sk2->sk_rcv_saddr,
106 ipv6_only_sock(sk2), match_wildcard);
107}
108EXPORT_SYMBOL(inet_rcv_saddr_equal);
109
110bool inet_rcv_saddr_any(const struct sock *sk)
111{
112#if IS_ENABLED(CONFIG_IPV6)
113 if (sk->sk_family == AF_INET6)
114 return ipv6_addr_any(&sk->sk_v6_rcv_saddr);
115#endif
116 return !sk->sk_rcv_saddr;
117}
118
119void inet_get_local_port_range(struct net *net, int *low, int *high)
120{
121 unsigned int seq;
122
123 do {
124 seq = read_seqbegin(&net->ipv4.ip_local_ports.lock);
125
126 *low = net->ipv4.ip_local_ports.range[0];
127 *high = net->ipv4.ip_local_ports.range[1];
128 } while (read_seqretry(&net->ipv4.ip_local_ports.lock, seq));
129}
130EXPORT_SYMBOL(inet_get_local_port_range);
131
132static int inet_csk_bind_conflict(const struct sock *sk,
133 const struct inet_bind_bucket *tb,
134 bool relax, bool reuseport_ok)
135{
136 struct sock *sk2;
137 bool reuse = sk->sk_reuse;
138 bool reuseport = !!sk->sk_reuseport && reuseport_ok;
139 kuid_t uid = sock_i_uid((struct sock *)sk);
140
141 /*
142 * Unlike other sk lookup places we do not check
143 * for sk_net here, since _all_ the socks listed
144 * in tb->owners list belong to the same net - the
145 * one this bucket belongs to.
146 */
147
148 sk_for_each_bound(sk2, &tb->owners) {
149 if (sk != sk2 &&
150 (!sk->sk_bound_dev_if ||
151 !sk2->sk_bound_dev_if ||
152 sk->sk_bound_dev_if == sk2->sk_bound_dev_if)) {
153 if ((!reuse || !sk2->sk_reuse ||
154 sk2->sk_state == TCP_LISTEN) &&
155 (!reuseport || !sk2->sk_reuseport ||
156 rcu_access_pointer(sk->sk_reuseport_cb) ||
157 (sk2->sk_state != TCP_TIME_WAIT &&
158 !uid_eq(uid, sock_i_uid(sk2))))) {
159 if (inet_rcv_saddr_equal(sk, sk2, true))
160 break;
161 }
162 if (!relax && reuse && sk2->sk_reuse &&
163 sk2->sk_state != TCP_LISTEN) {
164 if (inet_rcv_saddr_equal(sk, sk2, true))
165 break;
166 }
167 }
168 }
169 return sk2 != NULL;
170}
171
172/*
173 * Find an open port number for the socket. Returns with the
174 * inet_bind_hashbucket lock held.
175 */
176static struct inet_bind_hashbucket *
177inet_csk_find_open_port(struct sock *sk, struct inet_bind_bucket **tb_ret, int *port_ret)
178{
179 struct inet_hashinfo *hinfo = sk->sk_prot->h.hashinfo;
180 int port = 0;
181 struct inet_bind_hashbucket *head;
182 struct net *net = sock_net(sk);
183 int i, low, high, attempt_half;
184 struct inet_bind_bucket *tb;
185 u32 remaining, offset;
186
187 attempt_half = (sk->sk_reuse == SK_CAN_REUSE) ? 1 : 0;
188other_half_scan:
189 inet_get_local_port_range(net, &low, &high);
190 high++; /* [32768, 60999] -> [32768, 61000[ */
191 if (high - low < 4)
192 attempt_half = 0;
193 if (attempt_half) {
194 int half = low + (((high - low) >> 2) << 1);
195
196 if (attempt_half == 1)
197 high = half;
198 else
199 low = half;
200 }
201 remaining = high - low;
202 if (likely(remaining > 1))
203 remaining &= ~1U;
204
205 offset = prandom_u32() % remaining;
206 /* __inet_hash_connect() favors ports having @low parity
207 * We do the opposite to not pollute connect() users.
208 */
209 offset |= 1U;
210
211other_parity_scan:
212 port = low + offset;
213 for (i = 0; i < remaining; i += 2, port += 2) {
214 if (unlikely(port >= high))
215 port -= remaining;
216 if (inet_is_local_reserved_port(net, port))
217 continue;
218 head = &hinfo->bhash[inet_bhashfn(net, port,
219 hinfo->bhash_size)];
220 spin_lock_bh(&head->lock);
221 inet_bind_bucket_for_each(tb, &head->chain)
222 if (net_eq(ib_net(tb), net) && tb->port == port) {
223 if (!inet_csk_bind_conflict(sk, tb, false, false))
224 goto success;
225 goto next_port;
226 }
227 tb = NULL;
228 goto success;
229next_port:
230 spin_unlock_bh(&head->lock);
231 cond_resched();
232 }
233
234 offset--;
235 if (!(offset & 1))
236 goto other_parity_scan;
237
238 if (attempt_half == 1) {
239 /* OK we now try the upper half of the range */
240 attempt_half = 2;
241 goto other_half_scan;
242 }
243 return NULL;
244success:
245 *port_ret = port;
246 *tb_ret = tb;
247 return head;
248}
249
250static inline int sk_reuseport_match(struct inet_bind_bucket *tb,
251 struct sock *sk)
252{
253 kuid_t uid = sock_i_uid(sk);
254
255 if (tb->fastreuseport <= 0)
256 return 0;
257 if (!sk->sk_reuseport)
258 return 0;
259 if (rcu_access_pointer(sk->sk_reuseport_cb))
260 return 0;
261 if (!uid_eq(tb->fastuid, uid))
262 return 0;
263 /* We only need to check the rcv_saddr if this tb was once marked
264 * without fastreuseport and then was reset, as we can only know that
265 * the fast_*rcv_saddr doesn't have any conflicts with the socks on the
266 * owners list.
267 */
268 if (tb->fastreuseport == FASTREUSEPORT_ANY)
269 return 1;
270#if IS_ENABLED(CONFIG_IPV6)
271 if (tb->fast_sk_family == AF_INET6)
272 return ipv6_rcv_saddr_equal(&tb->fast_v6_rcv_saddr,
273 inet6_rcv_saddr(sk),
274 tb->fast_rcv_saddr,
275 sk->sk_rcv_saddr,
276 tb->fast_ipv6_only,
277 ipv6_only_sock(sk), true);
278#endif
279 return ipv4_rcv_saddr_equal(tb->fast_rcv_saddr, sk->sk_rcv_saddr,
280 ipv6_only_sock(sk), true);
281}
282
283/* Obtain a reference to a local port for the given sock,
284 * if snum is zero it means select any available local port.
285 * We try to allocate an odd port (and leave even ports for connect())
286 */
287int inet_csk_get_port(struct sock *sk, unsigned short snum)
288{
289 bool reuse = sk->sk_reuse && sk->sk_state != TCP_LISTEN;
290 struct inet_hashinfo *hinfo = sk->sk_prot->h.hashinfo;
291 int ret = 1, port = snum;
292 struct inet_bind_hashbucket *head;
293 struct net *net = sock_net(sk);
294 struct inet_bind_bucket *tb = NULL;
295 kuid_t uid = sock_i_uid(sk);
296
297 if (!port) {
298 head = inet_csk_find_open_port(sk, &tb, &port);
299 if (!head)
300 return ret;
301 if (!tb)
302 goto tb_not_found;
303 goto success;
304 }
305 head = &hinfo->bhash[inet_bhashfn(net, port,
306 hinfo->bhash_size)];
307 spin_lock_bh(&head->lock);
308 inet_bind_bucket_for_each(tb, &head->chain)
309 if (net_eq(ib_net(tb), net) && tb->port == port)
310 goto tb_found;
311tb_not_found:
312 tb = inet_bind_bucket_create(hinfo->bind_bucket_cachep,
313 net, head, port);
314 if (!tb)
315 goto fail_unlock;
316tb_found:
317 if (!hlist_empty(&tb->owners)) {
318 if (sk->sk_reuse == SK_FORCE_REUSE)
319 goto success;
320
321 if ((tb->fastreuse > 0 && reuse) ||
322 sk_reuseport_match(tb, sk))
323 goto success;
324 if (inet_csk_bind_conflict(sk, tb, true, true))
325 goto fail_unlock;
326 }
327success:
328 if (hlist_empty(&tb->owners)) {
329 tb->fastreuse = reuse;
330 if (sk->sk_reuseport) {
331 tb->fastreuseport = FASTREUSEPORT_ANY;
332 tb->fastuid = uid;
333 tb->fast_rcv_saddr = sk->sk_rcv_saddr;
334 tb->fast_ipv6_only = ipv6_only_sock(sk);
335 tb->fast_sk_family = sk->sk_family;
336#if IS_ENABLED(CONFIG_IPV6)
337 tb->fast_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
338#endif
339 } else {
340 tb->fastreuseport = 0;
341 }
342 } else {
343 if (!reuse)
344 tb->fastreuse = 0;
345 if (sk->sk_reuseport) {
346 /* We didn't match or we don't have fastreuseport set on
347 * the tb, but we have sk_reuseport set on this socket
348 * and we know that there are no bind conflicts with
349 * this socket in this tb, so reset our tb's reuseport
350 * settings so that any subsequent sockets that match
351 * our current socket will be put on the fast path.
352 *
353 * If we reset we need to set FASTREUSEPORT_STRICT so we
354 * do extra checking for all subsequent sk_reuseport
355 * socks.
356 */
357 if (!sk_reuseport_match(tb, sk)) {
358 tb->fastreuseport = FASTREUSEPORT_STRICT;
359 tb->fastuid = uid;
360 tb->fast_rcv_saddr = sk->sk_rcv_saddr;
361 tb->fast_ipv6_only = ipv6_only_sock(sk);
362 tb->fast_sk_family = sk->sk_family;
363#if IS_ENABLED(CONFIG_IPV6)
364 tb->fast_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
365#endif
366 }
367 } else {
368 tb->fastreuseport = 0;
369 }
370 }
371 if (!inet_csk(sk)->icsk_bind_hash)
372 inet_bind_hash(sk, tb, port);
373 WARN_ON(inet_csk(sk)->icsk_bind_hash != tb);
374 ret = 0;
375
376fail_unlock:
377 spin_unlock_bh(&head->lock);
378 return ret;
379}
380EXPORT_SYMBOL_GPL(inet_csk_get_port);
381
382/*
383 * Wait for an incoming connection, avoid race conditions. This must be called
384 * with the socket locked.
385 */
386static int inet_csk_wait_for_connect(struct sock *sk, long timeo)
387{
388 struct inet_connection_sock *icsk = inet_csk(sk);
389 DEFINE_WAIT(wait);
390 int err;
391
392 /*
393 * True wake-one mechanism for incoming connections: only
394 * one process gets woken up, not the 'whole herd'.
395 * Since we do not 'race & poll' for established sockets
396 * anymore, the common case will execute the loop only once.
397 *
398 * Subtle issue: "add_wait_queue_exclusive()" will be added
399 * after any current non-exclusive waiters, and we know that
400 * it will always _stay_ after any new non-exclusive waiters
401 * because all non-exclusive waiters are added at the
402 * beginning of the wait-queue. As such, it's ok to "drop"
403 * our exclusiveness temporarily when we get woken up without
404 * having to remove and re-insert us on the wait queue.
405 */
406 for (;;) {
407 prepare_to_wait_exclusive(sk_sleep(sk), &wait,
408 TASK_INTERRUPTIBLE);
409 release_sock(sk);
410 if (reqsk_queue_empty(&icsk->icsk_accept_queue))
411 timeo = schedule_timeout(timeo);
412 sched_annotate_sleep();
413 lock_sock(sk);
414 err = 0;
415 if (!reqsk_queue_empty(&icsk->icsk_accept_queue))
416 break;
417 err = -EINVAL;
418 if (sk->sk_state != TCP_LISTEN)
419 break;
420 err = sock_intr_errno(timeo);
421 if (signal_pending(current))
422 break;
423 err = -EAGAIN;
424 if (!timeo)
425 break;
426 }
427 finish_wait(sk_sleep(sk), &wait);
428 return err;
429}
430
431/*
432 * This will accept the next outstanding connection.
433 */
434struct sock *inet_csk_accept(struct sock *sk, int flags, int *err, bool kern)
435{
436 struct inet_connection_sock *icsk = inet_csk(sk);
437 struct request_sock_queue *queue = &icsk->icsk_accept_queue;
438 struct request_sock *req;
439 struct sock *newsk;
440 int error;
441
442 lock_sock(sk);
443
444 /* We need to make sure that this socket is listening,
445 * and that it has something pending.
446 */
447 error = -EINVAL;
448 if (sk->sk_state != TCP_LISTEN)
449 goto out_err;
450
451 /* Find already established connection */
452 if (reqsk_queue_empty(queue)) {
453 long timeo = sock_rcvtimeo(sk, flags & O_NONBLOCK);
454
455 /* If this is a non blocking socket don't sleep */
456 error = -EAGAIN;
457 if (!timeo)
458 goto out_err;
459
460 error = inet_csk_wait_for_connect(sk, timeo);
461 if (error)
462 goto out_err;
463 }
464 req = reqsk_queue_remove(queue, sk);
465 newsk = req->sk;
466
467 if (sk->sk_protocol == IPPROTO_TCP &&
468 tcp_rsk(req)->tfo_listener) {
469 spin_lock_bh(&queue->fastopenq.lock);
470 if (tcp_rsk(req)->tfo_listener) {
471 /* We are still waiting for the final ACK from 3WHS
472 * so can't free req now. Instead, we set req->sk to
473 * NULL to signify that the child socket is taken
474 * so reqsk_fastopen_remove() will free the req
475 * when 3WHS finishes (or is aborted).
476 */
477 req->sk = NULL;
478 req = NULL;
479 }
480 spin_unlock_bh(&queue->fastopenq.lock);
481 }
482out:
483 release_sock(sk);
484 if (req)
485 reqsk_put(req);
486 return newsk;
487out_err:
488 newsk = NULL;
489 req = NULL;
490 *err = error;
491 goto out;
492}
493EXPORT_SYMBOL(inet_csk_accept);
494
495/*
496 * Using different timers for retransmit, delayed acks and probes
497 * We may wish use just one timer maintaining a list of expire jiffies
498 * to optimize.
499 */
500void inet_csk_init_xmit_timers(struct sock *sk,
501 void (*retransmit_handler)(struct timer_list *t),
502 void (*delack_handler)(struct timer_list *t),
503 void (*keepalive_handler)(struct timer_list *t))
504{
505 struct inet_connection_sock *icsk = inet_csk(sk);
506
507 timer_setup(&icsk->icsk_retransmit_timer, retransmit_handler, 0);
508 timer_setup(&icsk->icsk_delack_timer, delack_handler, 0);
509 timer_setup(&sk->sk_timer, keepalive_handler, 0);
510 icsk->icsk_pending = icsk->icsk_ack.pending = 0;
511}
512EXPORT_SYMBOL(inet_csk_init_xmit_timers);
513
514void inet_csk_clear_xmit_timers(struct sock *sk)
515{
516 struct inet_connection_sock *icsk = inet_csk(sk);
517
518 icsk->icsk_pending = icsk->icsk_ack.pending = icsk->icsk_ack.blocked = 0;
519
520 sk_stop_timer(sk, &icsk->icsk_retransmit_timer);
521 sk_stop_timer(sk, &icsk->icsk_delack_timer);
522 sk_stop_timer(sk, &sk->sk_timer);
523}
524EXPORT_SYMBOL(inet_csk_clear_xmit_timers);
525
526void inet_csk_delete_keepalive_timer(struct sock *sk)
527{
528 sk_stop_timer(sk, &sk->sk_timer);
529}
530EXPORT_SYMBOL(inet_csk_delete_keepalive_timer);
531
532void inet_csk_reset_keepalive_timer(struct sock *sk, unsigned long len)
533{
534 sk_reset_timer(sk, &sk->sk_timer, jiffies + len);
535}
536EXPORT_SYMBOL(inet_csk_reset_keepalive_timer);
537
538struct dst_entry *inet_csk_route_req(const struct sock *sk,
539 struct flowi4 *fl4,
540 const struct request_sock *req)
541{
542 const struct inet_request_sock *ireq = inet_rsk(req);
543 struct net *net = read_pnet(&ireq->ireq_net);
544 struct ip_options_rcu *opt;
545 struct rtable *rt;
546
547 opt = ireq_opt_deref(ireq);
548
549 flowi4_init_output(fl4, ireq->ir_iif, ireq->ir_mark,
550 RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE,
551 sk->sk_protocol, inet_sk_flowi_flags(sk),
552 (opt && opt->opt.srr) ? opt->opt.faddr : ireq->ir_rmt_addr,
553 ireq->ir_loc_addr, ireq->ir_rmt_port,
554 htons(ireq->ir_num), sk->sk_uid);
555 security_req_classify_flow(req, flowi4_to_flowi(fl4));
556 rt = ip_route_output_flow(net, fl4, sk);
557 if (IS_ERR(rt))
558 goto no_route;
559 if (opt && opt->opt.is_strictroute && rt->rt_uses_gateway)
560 goto route_err;
561 return &rt->dst;
562
563route_err:
564 ip_rt_put(rt);
565no_route:
566 __IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
567 return NULL;
568}
569EXPORT_SYMBOL_GPL(inet_csk_route_req);
570
571struct dst_entry *inet_csk_route_child_sock(const struct sock *sk,
572 struct sock *newsk,
573 const struct request_sock *req)
574{
575 const struct inet_request_sock *ireq = inet_rsk(req);
576 struct net *net = read_pnet(&ireq->ireq_net);
577 struct inet_sock *newinet = inet_sk(newsk);
578 struct ip_options_rcu *opt;
579 struct flowi4 *fl4;
580 struct rtable *rt;
581
582 opt = rcu_dereference(ireq->ireq_opt);
583 fl4 = &newinet->cork.fl.u.ip4;
584
585 flowi4_init_output(fl4, ireq->ir_iif, ireq->ir_mark,
586 RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE,
587 sk->sk_protocol, inet_sk_flowi_flags(sk),
588 (opt && opt->opt.srr) ? opt->opt.faddr : ireq->ir_rmt_addr,
589 ireq->ir_loc_addr, ireq->ir_rmt_port,
590 htons(ireq->ir_num), sk->sk_uid);
591 security_req_classify_flow(req, flowi4_to_flowi(fl4));
592 rt = ip_route_output_flow(net, fl4, sk);
593 if (IS_ERR(rt))
594 goto no_route;
595 if (opt && opt->opt.is_strictroute && rt->rt_uses_gateway)
596 goto route_err;
597 return &rt->dst;
598
599route_err:
600 ip_rt_put(rt);
601no_route:
602 __IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
603 return NULL;
604}
605EXPORT_SYMBOL_GPL(inet_csk_route_child_sock);
606
607#if IS_ENABLED(CONFIG_IPV6)
608#define AF_INET_FAMILY(fam) ((fam) == AF_INET)
609#else
610#define AF_INET_FAMILY(fam) true
611#endif
612
613/* Decide when to expire the request and when to resend SYN-ACK */
614static inline void syn_ack_recalc(struct request_sock *req, const int thresh,
615 const int max_retries,
616 const u8 rskq_defer_accept,
617 int *expire, int *resend)
618{
619 if (!rskq_defer_accept) {
620 *expire = req->num_timeout >= thresh;
621 *resend = 1;
622 return;
623 }
624 *expire = req->num_timeout >= thresh &&
625 (!inet_rsk(req)->acked || req->num_timeout >= max_retries);
626 /*
627 * Do not resend while waiting for data after ACK,
628 * start to resend on end of deferring period to give
629 * last chance for data or ACK to create established socket.
630 */
631 *resend = !inet_rsk(req)->acked ||
632 req->num_timeout >= rskq_defer_accept - 1;
633}
634
635int inet_rtx_syn_ack(const struct sock *parent, struct request_sock *req)
636{
637 int err = req->rsk_ops->rtx_syn_ack(parent, req);
638
639 if (!err)
640 req->num_retrans++;
641 return err;
642}
643EXPORT_SYMBOL(inet_rtx_syn_ack);
644
645/* return true if req was found in the ehash table */
646static bool reqsk_queue_unlink(struct request_sock_queue *queue,
647 struct request_sock *req)
648{
649 struct inet_hashinfo *hashinfo = req_to_sk(req)->sk_prot->h.hashinfo;
650 bool found = false;
651
652 if (sk_hashed(req_to_sk(req))) {
653 spinlock_t *lock = inet_ehash_lockp(hashinfo, req->rsk_hash);
654
655 spin_lock(lock);
656 found = __sk_nulls_del_node_init_rcu(req_to_sk(req));
657 spin_unlock(lock);
658 }
659 if (timer_pending(&req->rsk_timer) && del_timer_sync(&req->rsk_timer))
660 reqsk_put(req);
661 return found;
662}
663
664void inet_csk_reqsk_queue_drop(struct sock *sk, struct request_sock *req)
665{
666 if (reqsk_queue_unlink(&inet_csk(sk)->icsk_accept_queue, req)) {
667 reqsk_queue_removed(&inet_csk(sk)->icsk_accept_queue, req);
668 reqsk_put(req);
669 }
670}
671EXPORT_SYMBOL(inet_csk_reqsk_queue_drop);
672
673void inet_csk_reqsk_queue_drop_and_put(struct sock *sk, struct request_sock *req)
674{
675 inet_csk_reqsk_queue_drop(sk, req);
676 reqsk_put(req);
677}
678EXPORT_SYMBOL(inet_csk_reqsk_queue_drop_and_put);
679
680static void reqsk_timer_handler(struct timer_list *t)
681{
682 struct request_sock *req = from_timer(req, t, rsk_timer);
683 struct sock *sk_listener = req->rsk_listener;
684 struct net *net = sock_net(sk_listener);
685 struct inet_connection_sock *icsk = inet_csk(sk_listener);
686 struct request_sock_queue *queue = &icsk->icsk_accept_queue;
687 int qlen, expire = 0, resend = 0;
688 int max_retries, thresh;
689 u8 defer_accept;
690
691 if (inet_sk_state_load(sk_listener) != TCP_LISTEN)
692 goto drop;
693
694 max_retries = icsk->icsk_syn_retries ? : net->ipv4.sysctl_tcp_synack_retries;
695 thresh = max_retries;
696 /* Normally all the openreqs are young and become mature
697 * (i.e. converted to established socket) for first timeout.
698 * If synack was not acknowledged for 1 second, it means
699 * one of the following things: synack was lost, ack was lost,
700 * rtt is high or nobody planned to ack (i.e. synflood).
701 * When server is a bit loaded, queue is populated with old
702 * open requests, reducing effective size of queue.
703 * When server is well loaded, queue size reduces to zero
704 * after several minutes of work. It is not synflood,
705 * it is normal operation. The solution is pruning
706 * too old entries overriding normal timeout, when
707 * situation becomes dangerous.
708 *
709 * Essentially, we reserve half of room for young
710 * embrions; and abort old ones without pity, if old
711 * ones are about to clog our table.
712 */
713 qlen = reqsk_queue_len(queue);
714 if ((qlen << 1) > max(8U, sk_listener->sk_max_ack_backlog)) {
715 int young = reqsk_queue_len_young(queue) << 1;
716
717 while (thresh > 2) {
718 if (qlen < young)
719 break;
720 thresh--;
721 young <<= 1;
722 }
723 }
724 defer_accept = READ_ONCE(queue->rskq_defer_accept);
725 if (defer_accept)
726 max_retries = defer_accept;
727 syn_ack_recalc(req, thresh, max_retries, defer_accept,
728 &expire, &resend);
729 req->rsk_ops->syn_ack_timeout(req);
730 if (!expire &&
731 (!resend ||
732 !inet_rtx_syn_ack(sk_listener, req) ||
733 inet_rsk(req)->acked)) {
734 unsigned long timeo;
735
736 if (req->num_timeout++ == 0)
737 atomic_dec(&queue->young);
738 timeo = min(TCP_TIMEOUT_INIT << req->num_timeout, TCP_RTO_MAX);
739 mod_timer(&req->rsk_timer, jiffies + timeo);
740 return;
741 }
742drop:
743 inet_csk_reqsk_queue_drop_and_put(sk_listener, req);
744}
745
746static void reqsk_queue_hash_req(struct request_sock *req,
747 unsigned long timeout)
748{
749 req->num_retrans = 0;
750 req->num_timeout = 0;
751 req->sk = NULL;
752
753 timer_setup(&req->rsk_timer, reqsk_timer_handler, TIMER_PINNED);
754 mod_timer(&req->rsk_timer, jiffies + timeout);
755
756 inet_ehash_insert(req_to_sk(req), NULL);
757 /* before letting lookups find us, make sure all req fields
758 * are committed to memory and refcnt initialized.
759 */
760 smp_wmb();
761 refcount_set(&req->rsk_refcnt, 2 + 1);
762}
763
764void inet_csk_reqsk_queue_hash_add(struct sock *sk, struct request_sock *req,
765 unsigned long timeout)
766{
767 reqsk_queue_hash_req(req, timeout);
768 inet_csk_reqsk_queue_added(sk);
769}
770EXPORT_SYMBOL_GPL(inet_csk_reqsk_queue_hash_add);
771
772/**
773 * inet_csk_clone_lock - clone an inet socket, and lock its clone
774 * @sk: the socket to clone
775 * @req: request_sock
776 * @priority: for allocation (%GFP_KERNEL, %GFP_ATOMIC, etc)
777 *
778 * Caller must unlock socket even in error path (bh_unlock_sock(newsk))
779 */
780struct sock *inet_csk_clone_lock(const struct sock *sk,
781 const struct request_sock *req,
782 const gfp_t priority)
783{
784 struct sock *newsk = sk_clone_lock(sk, priority);
785
786 if (newsk) {
787 struct inet_connection_sock *newicsk = inet_csk(newsk);
788
789 inet_sk_set_state(newsk, TCP_SYN_RECV);
790 newicsk->icsk_bind_hash = NULL;
791
792 inet_sk(newsk)->inet_dport = inet_rsk(req)->ir_rmt_port;
793 inet_sk(newsk)->inet_num = inet_rsk(req)->ir_num;
794 inet_sk(newsk)->inet_sport = htons(inet_rsk(req)->ir_num);
795
796 /* listeners have SOCK_RCU_FREE, not the children */
797 sock_reset_flag(newsk, SOCK_RCU_FREE);
798
799 inet_sk(newsk)->mc_list = NULL;
800
801 newsk->sk_mark = inet_rsk(req)->ir_mark;
802 atomic64_set(&newsk->sk_cookie,
803 atomic64_read(&inet_rsk(req)->ir_cookie));
804
805 newicsk->icsk_retransmits = 0;
806 newicsk->icsk_backoff = 0;
807 newicsk->icsk_probes_out = 0;
808
809 /* Deinitialize accept_queue to trap illegal accesses. */
810 memset(&newicsk->icsk_accept_queue, 0, sizeof(newicsk->icsk_accept_queue));
811
812 security_inet_csk_clone(newsk, req);
813 }
814 return newsk;
815}
816EXPORT_SYMBOL_GPL(inet_csk_clone_lock);
817
818/*
819 * At this point, there should be no process reference to this
820 * socket, and thus no user references at all. Therefore we
821 * can assume the socket waitqueue is inactive and nobody will
822 * try to jump onto it.
823 */
824void inet_csk_destroy_sock(struct sock *sk)
825{
826 WARN_ON(sk->sk_state != TCP_CLOSE);
827 WARN_ON(!sock_flag(sk, SOCK_DEAD));
828
829 /* It cannot be in hash table! */
830 WARN_ON(!sk_unhashed(sk));
831
832 /* If it has not 0 inet_sk(sk)->inet_num, it must be bound */
833 WARN_ON(inet_sk(sk)->inet_num && !inet_csk(sk)->icsk_bind_hash);
834
835 sk->sk_prot->destroy(sk);
836
837 sk_stream_kill_queues(sk);
838
839 xfrm_sk_free_policy(sk);
840
841 sk_refcnt_debug_release(sk);
842
843 percpu_counter_dec(sk->sk_prot->orphan_count);
844
845 sock_put(sk);
846}
847EXPORT_SYMBOL(inet_csk_destroy_sock);
848
849/* This function allows to force a closure of a socket after the call to
850 * tcp/dccp_create_openreq_child().
851 */
852void inet_csk_prepare_forced_close(struct sock *sk)
853 __releases(&sk->sk_lock.slock)
854{
855 /* sk_clone_lock locked the socket and set refcnt to 2 */
856 bh_unlock_sock(sk);
857 sock_put(sk);
858
859 /* The below has to be done to allow calling inet_csk_destroy_sock */
860 sock_set_flag(sk, SOCK_DEAD);
861 percpu_counter_inc(sk->sk_prot->orphan_count);
862 inet_sk(sk)->inet_num = 0;
863}
864EXPORT_SYMBOL(inet_csk_prepare_forced_close);
865
866int inet_csk_listen_start(struct sock *sk, int backlog)
867{
868 struct inet_connection_sock *icsk = inet_csk(sk);
869 struct inet_sock *inet = inet_sk(sk);
870 int err = -EADDRINUSE;
871
872 reqsk_queue_alloc(&icsk->icsk_accept_queue);
873
874 sk->sk_max_ack_backlog = backlog;
875 sk->sk_ack_backlog = 0;
876 inet_csk_delack_init(sk);
877
878 /* There is race window here: we announce ourselves listening,
879 * but this transition is still not validated by get_port().
880 * It is OK, because this socket enters to hash table only
881 * after validation is complete.
882 */
883 inet_sk_state_store(sk, TCP_LISTEN);
884 if (!sk->sk_prot->get_port(sk, inet->inet_num)) {
885 inet->inet_sport = htons(inet->inet_num);
886
887 sk_dst_reset(sk);
888 err = sk->sk_prot->hash(sk);
889
890 if (likely(!err))
891 return 0;
892 }
893
894 inet_sk_set_state(sk, TCP_CLOSE);
895 return err;
896}
897EXPORT_SYMBOL_GPL(inet_csk_listen_start);
898
899static void inet_child_forget(struct sock *sk, struct request_sock *req,
900 struct sock *child)
901{
902 sk->sk_prot->disconnect(child, O_NONBLOCK);
903
904 sock_orphan(child);
905
906 percpu_counter_inc(sk->sk_prot->orphan_count);
907
908 if (sk->sk_protocol == IPPROTO_TCP && tcp_rsk(req)->tfo_listener) {
909 BUG_ON(tcp_sk(child)->fastopen_rsk != req);
910 BUG_ON(sk != req->rsk_listener);
911
912 /* Paranoid, to prevent race condition if
913 * an inbound pkt destined for child is
914 * blocked by sock lock in tcp_v4_rcv().
915 * Also to satisfy an assertion in
916 * tcp_v4_destroy_sock().
917 */
918 tcp_sk(child)->fastopen_rsk = NULL;
919 }
920 inet_csk_destroy_sock(child);
921}
922
923struct sock *inet_csk_reqsk_queue_add(struct sock *sk,
924 struct request_sock *req,
925 struct sock *child)
926{
927 struct request_sock_queue *queue = &inet_csk(sk)->icsk_accept_queue;
928
929 spin_lock(&queue->rskq_lock);
930 if (unlikely(sk->sk_state != TCP_LISTEN)) {
931 inet_child_forget(sk, req, child);
932 child = NULL;
933 } else {
934 req->sk = child;
935 req->dl_next = NULL;
936 if (queue->rskq_accept_head == NULL)
937 queue->rskq_accept_head = req;
938 else
939 queue->rskq_accept_tail->dl_next = req;
940 queue->rskq_accept_tail = req;
941 sk_acceptq_added(sk);
942 }
943 spin_unlock(&queue->rskq_lock);
944 return child;
945}
946EXPORT_SYMBOL(inet_csk_reqsk_queue_add);
947
948struct sock *inet_csk_complete_hashdance(struct sock *sk, struct sock *child,
949 struct request_sock *req, bool own_req)
950{
951 if (own_req) {
952 inet_csk_reqsk_queue_drop(sk, req);
953 reqsk_queue_removed(&inet_csk(sk)->icsk_accept_queue, req);
954 if (inet_csk_reqsk_queue_add(sk, req, child))
955 return child;
956 }
957 /* Too bad, another child took ownership of the request, undo. */
958 bh_unlock_sock(child);
959 sock_put(child);
960 return NULL;
961}
962EXPORT_SYMBOL(inet_csk_complete_hashdance);
963
964/*
965 * This routine closes sockets which have been at least partially
966 * opened, but not yet accepted.
967 */
968void inet_csk_listen_stop(struct sock *sk)
969{
970 struct inet_connection_sock *icsk = inet_csk(sk);
971 struct request_sock_queue *queue = &icsk->icsk_accept_queue;
972 struct request_sock *next, *req;
973
974 /* Following specs, it would be better either to send FIN
975 * (and enter FIN-WAIT-1, it is normal close)
976 * or to send active reset (abort).
977 * Certainly, it is pretty dangerous while synflood, but it is
978 * bad justification for our negligence 8)
979 * To be honest, we are not able to make either
980 * of the variants now. --ANK
981 */
982 while ((req = reqsk_queue_remove(queue, sk)) != NULL) {
983 struct sock *child = req->sk;
984
985 local_bh_disable();
986 bh_lock_sock(child);
987 WARN_ON(sock_owned_by_user(child));
988 sock_hold(child);
989
990 inet_child_forget(sk, req, child);
991 reqsk_put(req);
992 bh_unlock_sock(child);
993 local_bh_enable();
994 sock_put(child);
995
996 cond_resched();
997 }
998 if (queue->fastopenq.rskq_rst_head) {
999 /* Free all the reqs queued in rskq_rst_head. */
1000 spin_lock_bh(&queue->fastopenq.lock);
1001 req = queue->fastopenq.rskq_rst_head;
1002 queue->fastopenq.rskq_rst_head = NULL;
1003 spin_unlock_bh(&queue->fastopenq.lock);
1004 while (req != NULL) {
1005 next = req->dl_next;
1006 reqsk_put(req);
1007 req = next;
1008 }
1009 }
1010 WARN_ON_ONCE(sk->sk_ack_backlog);
1011}
1012EXPORT_SYMBOL_GPL(inet_csk_listen_stop);
1013
1014void inet_csk_addr2sockaddr(struct sock *sk, struct sockaddr *uaddr)
1015{
1016 struct sockaddr_in *sin = (struct sockaddr_in *)uaddr;
1017 const struct inet_sock *inet = inet_sk(sk);
1018
1019 sin->sin_family = AF_INET;
1020 sin->sin_addr.s_addr = inet->inet_daddr;
1021 sin->sin_port = inet->inet_dport;
1022}
1023EXPORT_SYMBOL_GPL(inet_csk_addr2sockaddr);
1024
1025#ifdef CONFIG_COMPAT
1026int inet_csk_compat_getsockopt(struct sock *sk, int level, int optname,
1027 char __user *optval, int __user *optlen)
1028{
1029 const struct inet_connection_sock *icsk = inet_csk(sk);
1030
1031 if (icsk->icsk_af_ops->compat_getsockopt)
1032 return icsk->icsk_af_ops->compat_getsockopt(sk, level, optname,
1033 optval, optlen);
1034 return icsk->icsk_af_ops->getsockopt(sk, level, optname,
1035 optval, optlen);
1036}
1037EXPORT_SYMBOL_GPL(inet_csk_compat_getsockopt);
1038
1039int inet_csk_compat_setsockopt(struct sock *sk, int level, int optname,
1040 char __user *optval, unsigned int optlen)
1041{
1042 const struct inet_connection_sock *icsk = inet_csk(sk);
1043
1044 if (icsk->icsk_af_ops->compat_setsockopt)
1045 return icsk->icsk_af_ops->compat_setsockopt(sk, level, optname,
1046 optval, optlen);
1047 return icsk->icsk_af_ops->setsockopt(sk, level, optname,
1048 optval, optlen);
1049}
1050EXPORT_SYMBOL_GPL(inet_csk_compat_setsockopt);
1051#endif
1052
1053static struct dst_entry *inet_csk_rebuild_route(struct sock *sk, struct flowi *fl)
1054{
1055 const struct inet_sock *inet = inet_sk(sk);
1056 const struct ip_options_rcu *inet_opt;
1057 __be32 daddr = inet->inet_daddr;
1058 struct flowi4 *fl4;
1059 struct rtable *rt;
1060
1061 rcu_read_lock();
1062 inet_opt = rcu_dereference(inet->inet_opt);
1063 if (inet_opt && inet_opt->opt.srr)
1064 daddr = inet_opt->opt.faddr;
1065 fl4 = &fl->u.ip4;
1066 rt = ip_route_output_ports(sock_net(sk), fl4, sk, daddr,
1067 inet->inet_saddr, inet->inet_dport,
1068 inet->inet_sport, sk->sk_protocol,
1069 RT_CONN_FLAGS(sk), sk->sk_bound_dev_if);
1070 if (IS_ERR(rt))
1071 rt = NULL;
1072 if (rt)
1073 sk_setup_caps(sk, &rt->dst);
1074 rcu_read_unlock();
1075
1076 return &rt->dst;
1077}
1078
1079struct dst_entry *inet_csk_update_pmtu(struct sock *sk, u32 mtu)
1080{
1081 struct dst_entry *dst = __sk_dst_check(sk, 0);
1082 struct inet_sock *inet = inet_sk(sk);
1083
1084 if (!dst) {
1085 dst = inet_csk_rebuild_route(sk, &inet->cork.fl);
1086 if (!dst)
1087 goto out;
1088 }
1089 dst->ops->update_pmtu(dst, sk, NULL, mtu);
1090
1091 dst = __sk_dst_check(sk, 0);
1092 if (!dst)
1093 dst = inet_csk_rebuild_route(sk, &inet->cork.fl);
1094out:
1095 return dst;
1096}
1097EXPORT_SYMBOL_GPL(inet_csk_update_pmtu);
1098