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1/*
2 * INET An implementation of the TCP/IP protocol suite for the LINUX
3 * operating system. INET is implemented using the BSD Socket
4 * interface as the means of communication with the user level.
5 *
6 * 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#ifdef INET_CSK_DEBUG
31const char inet_csk_timer_bug_msg[] = "inet_csk BUG: unknown timer value\n";
32EXPORT_SYMBOL(inet_csk_timer_bug_msg);
33#endif
34
35#if IS_ENABLED(CONFIG_IPV6)
36/* match_wildcard == true: IPV6_ADDR_ANY equals to any IPv6 addresses if IPv6
37 * only, and any IPv4 addresses if not IPv6 only
38 * match_wildcard == false: addresses must be exactly the same, i.e.
39 * IPV6_ADDR_ANY only equals to IPV6_ADDR_ANY,
40 * and 0.0.0.0 equals to 0.0.0.0 only
41 */
42static bool ipv6_rcv_saddr_equal(const struct in6_addr *sk1_rcv_saddr6,
43 const struct in6_addr *sk2_rcv_saddr6,
44 __be32 sk1_rcv_saddr, __be32 sk2_rcv_saddr,
45 bool sk1_ipv6only, bool sk2_ipv6only,
46 bool match_wildcard)
47{
48 int addr_type = ipv6_addr_type(sk1_rcv_saddr6);
49 int addr_type2 = sk2_rcv_saddr6 ? ipv6_addr_type(sk2_rcv_saddr6) : IPV6_ADDR_MAPPED;
50
51 /* if both are mapped, treat as IPv4 */
52 if (addr_type == IPV6_ADDR_MAPPED && addr_type2 == IPV6_ADDR_MAPPED) {
53 if (!sk2_ipv6only) {
54 if (sk1_rcv_saddr == sk2_rcv_saddr)
55 return true;
56 if (!sk1_rcv_saddr || !sk2_rcv_saddr)
57 return match_wildcard;
58 }
59 return false;
60 }
61
62 if (addr_type == IPV6_ADDR_ANY && addr_type2 == IPV6_ADDR_ANY)
63 return true;
64
65 if (addr_type2 == IPV6_ADDR_ANY && match_wildcard &&
66 !(sk2_ipv6only && addr_type == IPV6_ADDR_MAPPED))
67 return true;
68
69 if (addr_type == IPV6_ADDR_ANY && match_wildcard &&
70 !(sk1_ipv6only && addr_type2 == IPV6_ADDR_MAPPED))
71 return true;
72
73 if (sk2_rcv_saddr6 &&
74 ipv6_addr_equal(sk1_rcv_saddr6, sk2_rcv_saddr6))
75 return true;
76
77 return false;
78}
79#endif
80
81/* match_wildcard == true: 0.0.0.0 equals to any IPv4 addresses
82 * match_wildcard == false: addresses must be exactly the same, i.e.
83 * 0.0.0.0 only equals to 0.0.0.0
84 */
85static bool ipv4_rcv_saddr_equal(__be32 sk1_rcv_saddr, __be32 sk2_rcv_saddr,
86 bool sk2_ipv6only, bool match_wildcard)
87{
88 if (!sk2_ipv6only) {
89 if (sk1_rcv_saddr == sk2_rcv_saddr)
90 return true;
91 if (!sk1_rcv_saddr || !sk2_rcv_saddr)
92 return match_wildcard;
93 }
94 return false;
95}
96
97bool inet_rcv_saddr_equal(const struct sock *sk, const struct sock *sk2,
98 bool match_wildcard)
99{
100#if IS_ENABLED(CONFIG_IPV6)
101 if (sk->sk_family == AF_INET6)
102 return ipv6_rcv_saddr_equal(&sk->sk_v6_rcv_saddr,
103 inet6_rcv_saddr(sk2),
104 sk->sk_rcv_saddr,
105 sk2->sk_rcv_saddr,
106 ipv6_only_sock(sk),
107 ipv6_only_sock(sk2),
108 match_wildcard);
109#endif
110 return ipv4_rcv_saddr_equal(sk->sk_rcv_saddr, sk2->sk_rcv_saddr,
111 ipv6_only_sock(sk2), match_wildcard);
112}
113EXPORT_SYMBOL(inet_rcv_saddr_equal);
114
115void inet_get_local_port_range(struct net *net, int *low, int *high)
116{
117 unsigned int seq;
118
119 do {
120 seq = read_seqbegin(&net->ipv4.ip_local_ports.lock);
121
122 *low = net->ipv4.ip_local_ports.range[0];
123 *high = net->ipv4.ip_local_ports.range[1];
124 } while (read_seqretry(&net->ipv4.ip_local_ports.lock, seq));
125}
126EXPORT_SYMBOL(inet_get_local_port_range);
127
128static int inet_csk_bind_conflict(const struct sock *sk,
129 const struct inet_bind_bucket *tb,
130 bool relax, bool reuseport_ok)
131{
132 struct sock *sk2;
133 bool reuse = sk->sk_reuse;
134 bool reuseport = !!sk->sk_reuseport && reuseport_ok;
135 kuid_t uid = sock_i_uid((struct sock *)sk);
136
137 /*
138 * Unlike other sk lookup places we do not check
139 * for sk_net here, since _all_ the socks listed
140 * in tb->owners list belong to the same net - the
141 * one this bucket belongs to.
142 */
143
144 sk_for_each_bound(sk2, &tb->owners) {
145 if (sk != sk2 &&
146 (!sk->sk_bound_dev_if ||
147 !sk2->sk_bound_dev_if ||
148 sk->sk_bound_dev_if == sk2->sk_bound_dev_if)) {
149 if ((!reuse || !sk2->sk_reuse ||
150 sk2->sk_state == TCP_LISTEN) &&
151 (!reuseport || !sk2->sk_reuseport ||
152 rcu_access_pointer(sk->sk_reuseport_cb) ||
153 (sk2->sk_state != TCP_TIME_WAIT &&
154 !uid_eq(uid, sock_i_uid(sk2))))) {
155 if (inet_rcv_saddr_equal(sk, sk2, true))
156 break;
157 }
158 if (!relax && reuse && sk2->sk_reuse &&
159 sk2->sk_state != TCP_LISTEN) {
160 if (inet_rcv_saddr_equal(sk, sk2, true))
161 break;
162 }
163 }
164 }
165 return sk2 != NULL;
166}
167
168/*
169 * Find an open port number for the socket. Returns with the
170 * inet_bind_hashbucket lock held.
171 */
172static struct inet_bind_hashbucket *
173inet_csk_find_open_port(struct sock *sk, struct inet_bind_bucket **tb_ret, int *port_ret)
174{
175 struct inet_hashinfo *hinfo = sk->sk_prot->h.hashinfo;
176 int port = 0;
177 struct inet_bind_hashbucket *head;
178 struct net *net = sock_net(sk);
179 int i, low, high, attempt_half;
180 struct inet_bind_bucket *tb;
181 u32 remaining, offset;
182
183 attempt_half = (sk->sk_reuse == SK_CAN_REUSE) ? 1 : 0;
184other_half_scan:
185 inet_get_local_port_range(net, &low, &high);
186 high++; /* [32768, 60999] -> [32768, 61000[ */
187 if (high - low < 4)
188 attempt_half = 0;
189 if (attempt_half) {
190 int half = low + (((high - low) >> 2) << 1);
191
192 if (attempt_half == 1)
193 high = half;
194 else
195 low = half;
196 }
197 remaining = high - low;
198 if (likely(remaining > 1))
199 remaining &= ~1U;
200
201 offset = prandom_u32() % remaining;
202 /* __inet_hash_connect() favors ports having @low parity
203 * We do the opposite to not pollute connect() users.
204 */
205 offset |= 1U;
206
207other_parity_scan:
208 port = low + offset;
209 for (i = 0; i < remaining; i += 2, port += 2) {
210 if (unlikely(port >= high))
211 port -= remaining;
212 if (inet_is_local_reserved_port(net, port))
213 continue;
214 head = &hinfo->bhash[inet_bhashfn(net, port,
215 hinfo->bhash_size)];
216 spin_lock_bh(&head->lock);
217 inet_bind_bucket_for_each(tb, &head->chain)
218 if (net_eq(ib_net(tb), net) && tb->port == port) {
219 if (!inet_csk_bind_conflict(sk, tb, false, false))
220 goto success;
221 goto next_port;
222 }
223 tb = NULL;
224 goto success;
225next_port:
226 spin_unlock_bh(&head->lock);
227 cond_resched();
228 }
229
230 offset--;
231 if (!(offset & 1))
232 goto other_parity_scan;
233
234 if (attempt_half == 1) {
235 /* OK we now try the upper half of the range */
236 attempt_half = 2;
237 goto other_half_scan;
238 }
239 return NULL;
240success:
241 *port_ret = port;
242 *tb_ret = tb;
243 return head;
244}
245
246static inline int sk_reuseport_match(struct inet_bind_bucket *tb,
247 struct sock *sk)
248{
249 kuid_t uid = sock_i_uid(sk);
250
251 if (tb->fastreuseport <= 0)
252 return 0;
253 if (!sk->sk_reuseport)
254 return 0;
255 if (rcu_access_pointer(sk->sk_reuseport_cb))
256 return 0;
257 if (!uid_eq(tb->fastuid, uid))
258 return 0;
259 /* We only need to check the rcv_saddr if this tb was once marked
260 * without fastreuseport and then was reset, as we can only know that
261 * the fast_*rcv_saddr doesn't have any conflicts with the socks on the
262 * owners list.
263 */
264 if (tb->fastreuseport == FASTREUSEPORT_ANY)
265 return 1;
266#if IS_ENABLED(CONFIG_IPV6)
267 if (tb->fast_sk_family == AF_INET6)
268 return ipv6_rcv_saddr_equal(&tb->fast_v6_rcv_saddr,
269 inet6_rcv_saddr(sk),
270 tb->fast_rcv_saddr,
271 sk->sk_rcv_saddr,
272 tb->fast_ipv6_only,
273 ipv6_only_sock(sk), true);
274#endif
275 return ipv4_rcv_saddr_equal(tb->fast_rcv_saddr, sk->sk_rcv_saddr,
276 ipv6_only_sock(sk), true);
277}
278
279/* Obtain a reference to a local port for the given sock,
280 * if snum is zero it means select any available local port.
281 * We try to allocate an odd port (and leave even ports for connect())
282 */
283int inet_csk_get_port(struct sock *sk, unsigned short snum)
284{
285 bool reuse = sk->sk_reuse && sk->sk_state != TCP_LISTEN;
286 struct inet_hashinfo *hinfo = sk->sk_prot->h.hashinfo;
287 int ret = 1, port = snum;
288 struct inet_bind_hashbucket *head;
289 struct net *net = sock_net(sk);
290 struct inet_bind_bucket *tb = NULL;
291 kuid_t uid = sock_i_uid(sk);
292
293 if (!port) {
294 head = inet_csk_find_open_port(sk, &tb, &port);
295 if (!head)
296 return ret;
297 if (!tb)
298 goto tb_not_found;
299 goto success;
300 }
301 head = &hinfo->bhash[inet_bhashfn(net, port,
302 hinfo->bhash_size)];
303 spin_lock_bh(&head->lock);
304 inet_bind_bucket_for_each(tb, &head->chain)
305 if (net_eq(ib_net(tb), net) && tb->port == port)
306 goto tb_found;
307tb_not_found:
308 tb = inet_bind_bucket_create(hinfo->bind_bucket_cachep,
309 net, head, port);
310 if (!tb)
311 goto fail_unlock;
312tb_found:
313 if (!hlist_empty(&tb->owners)) {
314 if (sk->sk_reuse == SK_FORCE_REUSE)
315 goto success;
316
317 if ((tb->fastreuse > 0 && reuse) ||
318 sk_reuseport_match(tb, sk))
319 goto success;
320 if (inet_csk_bind_conflict(sk, tb, true, true))
321 goto fail_unlock;
322 }
323success:
324 if (hlist_empty(&tb->owners)) {
325 tb->fastreuse = reuse;
326 if (sk->sk_reuseport) {
327 tb->fastreuseport = FASTREUSEPORT_ANY;
328 tb->fastuid = uid;
329 tb->fast_rcv_saddr = sk->sk_rcv_saddr;
330 tb->fast_ipv6_only = ipv6_only_sock(sk);
331 tb->fast_sk_family = sk->sk_family;
332#if IS_ENABLED(CONFIG_IPV6)
333 tb->fast_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
334#endif
335 } else {
336 tb->fastreuseport = 0;
337 }
338 } else {
339 if (!reuse)
340 tb->fastreuse = 0;
341 if (sk->sk_reuseport) {
342 /* We didn't match or we don't have fastreuseport set on
343 * the tb, but we have sk_reuseport set on this socket
344 * and we know that there are no bind conflicts with
345 * this socket in this tb, so reset our tb's reuseport
346 * settings so that any subsequent sockets that match
347 * our current socket will be put on the fast path.
348 *
349 * If we reset we need to set FASTREUSEPORT_STRICT so we
350 * do extra checking for all subsequent sk_reuseport
351 * socks.
352 */
353 if (!sk_reuseport_match(tb, sk)) {
354 tb->fastreuseport = FASTREUSEPORT_STRICT;
355 tb->fastuid = uid;
356 tb->fast_rcv_saddr = sk->sk_rcv_saddr;
357 tb->fast_ipv6_only = ipv6_only_sock(sk);
358 tb->fast_sk_family = sk->sk_family;
359#if IS_ENABLED(CONFIG_IPV6)
360 tb->fast_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
361#endif
362 }
363 } else {
364 tb->fastreuseport = 0;
365 }
366 }
367 if (!inet_csk(sk)->icsk_bind_hash)
368 inet_bind_hash(sk, tb, port);
369 WARN_ON(inet_csk(sk)->icsk_bind_hash != tb);
370 ret = 0;
371
372fail_unlock:
373 spin_unlock_bh(&head->lock);
374 return ret;
375}
376EXPORT_SYMBOL_GPL(inet_csk_get_port);
377
378/*
379 * Wait for an incoming connection, avoid race conditions. This must be called
380 * with the socket locked.
381 */
382static int inet_csk_wait_for_connect(struct sock *sk, long timeo)
383{
384 struct inet_connection_sock *icsk = inet_csk(sk);
385 DEFINE_WAIT(wait);
386 int err;
387
388 /*
389 * True wake-one mechanism for incoming connections: only
390 * one process gets woken up, not the 'whole herd'.
391 * Since we do not 'race & poll' for established sockets
392 * anymore, the common case will execute the loop only once.
393 *
394 * Subtle issue: "add_wait_queue_exclusive()" will be added
395 * after any current non-exclusive waiters, and we know that
396 * it will always _stay_ after any new non-exclusive waiters
397 * because all non-exclusive waiters are added at the
398 * beginning of the wait-queue. As such, it's ok to "drop"
399 * our exclusiveness temporarily when we get woken up without
400 * having to remove and re-insert us on the wait queue.
401 */
402 for (;;) {
403 prepare_to_wait_exclusive(sk_sleep(sk), &wait,
404 TASK_INTERRUPTIBLE);
405 release_sock(sk);
406 if (reqsk_queue_empty(&icsk->icsk_accept_queue))
407 timeo = schedule_timeout(timeo);
408 sched_annotate_sleep();
409 lock_sock(sk);
410 err = 0;
411 if (!reqsk_queue_empty(&icsk->icsk_accept_queue))
412 break;
413 err = -EINVAL;
414 if (sk->sk_state != TCP_LISTEN)
415 break;
416 err = sock_intr_errno(timeo);
417 if (signal_pending(current))
418 break;
419 err = -EAGAIN;
420 if (!timeo)
421 break;
422 }
423 finish_wait(sk_sleep(sk), &wait);
424 return err;
425}
426
427/*
428 * This will accept the next outstanding connection.
429 */
430struct sock *inet_csk_accept(struct sock *sk, int flags, int *err, bool kern)
431{
432 struct inet_connection_sock *icsk = inet_csk(sk);
433 struct request_sock_queue *queue = &icsk->icsk_accept_queue;
434 struct request_sock *req;
435 struct sock *newsk;
436 int error;
437
438 lock_sock(sk);
439
440 /* We need to make sure that this socket is listening,
441 * and that it has something pending.
442 */
443 error = -EINVAL;
444 if (sk->sk_state != TCP_LISTEN)
445 goto out_err;
446
447 /* Find already established connection */
448 if (reqsk_queue_empty(queue)) {
449 long timeo = sock_rcvtimeo(sk, flags & O_NONBLOCK);
450
451 /* If this is a non blocking socket don't sleep */
452 error = -EAGAIN;
453 if (!timeo)
454 goto out_err;
455
456 error = inet_csk_wait_for_connect(sk, timeo);
457 if (error)
458 goto out_err;
459 }
460 req = reqsk_queue_remove(queue, sk);
461 newsk = req->sk;
462
463 if (sk->sk_protocol == IPPROTO_TCP &&
464 tcp_rsk(req)->tfo_listener) {
465 spin_lock_bh(&queue->fastopenq.lock);
466 if (tcp_rsk(req)->tfo_listener) {
467 /* We are still waiting for the final ACK from 3WHS
468 * so can't free req now. Instead, we set req->sk to
469 * NULL to signify that the child socket is taken
470 * so reqsk_fastopen_remove() will free the req
471 * when 3WHS finishes (or is aborted).
472 */
473 req->sk = NULL;
474 req = NULL;
475 }
476 spin_unlock_bh(&queue->fastopenq.lock);
477 }
478out:
479 release_sock(sk);
480 if (req)
481 reqsk_put(req);
482 return newsk;
483out_err:
484 newsk = NULL;
485 req = NULL;
486 *err = error;
487 goto out;
488}
489EXPORT_SYMBOL(inet_csk_accept);
490
491/*
492 * Using different timers for retransmit, delayed acks and probes
493 * We may wish use just one timer maintaining a list of expire jiffies
494 * to optimize.
495 */
496void inet_csk_init_xmit_timers(struct sock *sk,
497 void (*retransmit_handler)(struct timer_list *t),
498 void (*delack_handler)(struct timer_list *t),
499 void (*keepalive_handler)(struct timer_list *t))
500{
501 struct inet_connection_sock *icsk = inet_csk(sk);
502
503 timer_setup(&icsk->icsk_retransmit_timer, retransmit_handler, 0);
504 timer_setup(&icsk->icsk_delack_timer, delack_handler, 0);
505 timer_setup(&sk->sk_timer, keepalive_handler, 0);
506 icsk->icsk_pending = icsk->icsk_ack.pending = 0;
507}
508EXPORT_SYMBOL(inet_csk_init_xmit_timers);
509
510void inet_csk_clear_xmit_timers(struct sock *sk)
511{
512 struct inet_connection_sock *icsk = inet_csk(sk);
513
514 icsk->icsk_pending = icsk->icsk_ack.pending = icsk->icsk_ack.blocked = 0;
515
516 sk_stop_timer(sk, &icsk->icsk_retransmit_timer);
517 sk_stop_timer(sk, &icsk->icsk_delack_timer);
518 sk_stop_timer(sk, &sk->sk_timer);
519}
520EXPORT_SYMBOL(inet_csk_clear_xmit_timers);
521
522void inet_csk_delete_keepalive_timer(struct sock *sk)
523{
524 sk_stop_timer(sk, &sk->sk_timer);
525}
526EXPORT_SYMBOL(inet_csk_delete_keepalive_timer);
527
528void inet_csk_reset_keepalive_timer(struct sock *sk, unsigned long len)
529{
530 sk_reset_timer(sk, &sk->sk_timer, jiffies + len);
531}
532EXPORT_SYMBOL(inet_csk_reset_keepalive_timer);
533
534struct dst_entry *inet_csk_route_req(const struct sock *sk,
535 struct flowi4 *fl4,
536 const struct request_sock *req)
537{
538 const struct inet_request_sock *ireq = inet_rsk(req);
539 struct net *net = read_pnet(&ireq->ireq_net);
540 struct ip_options_rcu *opt;
541 struct rtable *rt;
542
543 opt = ireq_opt_deref(ireq);
544
545 flowi4_init_output(fl4, ireq->ir_iif, ireq->ir_mark,
546 RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE,
547 sk->sk_protocol, inet_sk_flowi_flags(sk),
548 (opt && opt->opt.srr) ? opt->opt.faddr : ireq->ir_rmt_addr,
549 ireq->ir_loc_addr, ireq->ir_rmt_port,
550 htons(ireq->ir_num), sk->sk_uid);
551 security_req_classify_flow(req, flowi4_to_flowi(fl4));
552 rt = ip_route_output_flow(net, fl4, sk);
553 if (IS_ERR(rt))
554 goto no_route;
555 if (opt && opt->opt.is_strictroute && rt->rt_uses_gateway)
556 goto route_err;
557 return &rt->dst;
558
559route_err:
560 ip_rt_put(rt);
561no_route:
562 __IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
563 return NULL;
564}
565EXPORT_SYMBOL_GPL(inet_csk_route_req);
566
567struct dst_entry *inet_csk_route_child_sock(const struct sock *sk,
568 struct sock *newsk,
569 const struct request_sock *req)
570{
571 const struct inet_request_sock *ireq = inet_rsk(req);
572 struct net *net = read_pnet(&ireq->ireq_net);
573 struct inet_sock *newinet = inet_sk(newsk);
574 struct ip_options_rcu *opt;
575 struct flowi4 *fl4;
576 struct rtable *rt;
577
578 opt = rcu_dereference(ireq->ireq_opt);
579 fl4 = &newinet->cork.fl.u.ip4;
580
581 flowi4_init_output(fl4, ireq->ir_iif, ireq->ir_mark,
582 RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE,
583 sk->sk_protocol, inet_sk_flowi_flags(sk),
584 (opt && opt->opt.srr) ? opt->opt.faddr : ireq->ir_rmt_addr,
585 ireq->ir_loc_addr, ireq->ir_rmt_port,
586 htons(ireq->ir_num), sk->sk_uid);
587 security_req_classify_flow(req, flowi4_to_flowi(fl4));
588 rt = ip_route_output_flow(net, fl4, sk);
589 if (IS_ERR(rt))
590 goto no_route;
591 if (opt && opt->opt.is_strictroute && rt->rt_uses_gateway)
592 goto route_err;
593 return &rt->dst;
594
595route_err:
596 ip_rt_put(rt);
597no_route:
598 __IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
599 return NULL;
600}
601EXPORT_SYMBOL_GPL(inet_csk_route_child_sock);
602
603#if IS_ENABLED(CONFIG_IPV6)
604#define AF_INET_FAMILY(fam) ((fam) == AF_INET)
605#else
606#define AF_INET_FAMILY(fam) true
607#endif
608
609/* Decide when to expire the request and when to resend SYN-ACK */
610static inline void syn_ack_recalc(struct request_sock *req, const int thresh,
611 const int max_retries,
612 const u8 rskq_defer_accept,
613 int *expire, int *resend)
614{
615 if (!rskq_defer_accept) {
616 *expire = req->num_timeout >= thresh;
617 *resend = 1;
618 return;
619 }
620 *expire = req->num_timeout >= thresh &&
621 (!inet_rsk(req)->acked || req->num_timeout >= max_retries);
622 /*
623 * Do not resend while waiting for data after ACK,
624 * start to resend on end of deferring period to give
625 * last chance for data or ACK to create established socket.
626 */
627 *resend = !inet_rsk(req)->acked ||
628 req->num_timeout >= rskq_defer_accept - 1;
629}
630
631int inet_rtx_syn_ack(const struct sock *parent, struct request_sock *req)
632{
633 int err = req->rsk_ops->rtx_syn_ack(parent, req);
634
635 if (!err)
636 req->num_retrans++;
637 return err;
638}
639EXPORT_SYMBOL(inet_rtx_syn_ack);
640
641/* return true if req was found in the ehash table */
642static bool reqsk_queue_unlink(struct request_sock_queue *queue,
643 struct request_sock *req)
644{
645 struct inet_hashinfo *hashinfo = req_to_sk(req)->sk_prot->h.hashinfo;
646 bool found = false;
647
648 if (sk_hashed(req_to_sk(req))) {
649 spinlock_t *lock = inet_ehash_lockp(hashinfo, req->rsk_hash);
650
651 spin_lock(lock);
652 found = __sk_nulls_del_node_init_rcu(req_to_sk(req));
653 spin_unlock(lock);
654 }
655 if (timer_pending(&req->rsk_timer) && del_timer_sync(&req->rsk_timer))
656 reqsk_put(req);
657 return found;
658}
659
660void inet_csk_reqsk_queue_drop(struct sock *sk, struct request_sock *req)
661{
662 if (reqsk_queue_unlink(&inet_csk(sk)->icsk_accept_queue, req)) {
663 reqsk_queue_removed(&inet_csk(sk)->icsk_accept_queue, req);
664 reqsk_put(req);
665 }
666}
667EXPORT_SYMBOL(inet_csk_reqsk_queue_drop);
668
669void inet_csk_reqsk_queue_drop_and_put(struct sock *sk, struct request_sock *req)
670{
671 inet_csk_reqsk_queue_drop(sk, req);
672 reqsk_put(req);
673}
674EXPORT_SYMBOL(inet_csk_reqsk_queue_drop_and_put);
675
676static void reqsk_timer_handler(struct timer_list *t)
677{
678 struct request_sock *req = from_timer(req, t, rsk_timer);
679 struct sock *sk_listener = req->rsk_listener;
680 struct net *net = sock_net(sk_listener);
681 struct inet_connection_sock *icsk = inet_csk(sk_listener);
682 struct request_sock_queue *queue = &icsk->icsk_accept_queue;
683 int qlen, expire = 0, resend = 0;
684 int max_retries, thresh;
685 u8 defer_accept;
686
687 if (inet_sk_state_load(sk_listener) != TCP_LISTEN)
688 goto drop;
689
690 max_retries = icsk->icsk_syn_retries ? : net->ipv4.sysctl_tcp_synack_retries;
691 thresh = max_retries;
692 /* Normally all the openreqs are young and become mature
693 * (i.e. converted to established socket) for first timeout.
694 * If synack was not acknowledged for 1 second, it means
695 * one of the following things: synack was lost, ack was lost,
696 * rtt is high or nobody planned to ack (i.e. synflood).
697 * When server is a bit loaded, queue is populated with old
698 * open requests, reducing effective size of queue.
699 * When server is well loaded, queue size reduces to zero
700 * after several minutes of work. It is not synflood,
701 * it is normal operation. The solution is pruning
702 * too old entries overriding normal timeout, when
703 * situation becomes dangerous.
704 *
705 * Essentially, we reserve half of room for young
706 * embrions; and abort old ones without pity, if old
707 * ones are about to clog our table.
708 */
709 qlen = reqsk_queue_len(queue);
710 if ((qlen << 1) > max(8U, sk_listener->sk_max_ack_backlog)) {
711 int young = reqsk_queue_len_young(queue) << 1;
712
713 while (thresh > 2) {
714 if (qlen < young)
715 break;
716 thresh--;
717 young <<= 1;
718 }
719 }
720 defer_accept = READ_ONCE(queue->rskq_defer_accept);
721 if (defer_accept)
722 max_retries = defer_accept;
723 syn_ack_recalc(req, thresh, max_retries, defer_accept,
724 &expire, &resend);
725 req->rsk_ops->syn_ack_timeout(req);
726 if (!expire &&
727 (!resend ||
728 !inet_rtx_syn_ack(sk_listener, req) ||
729 inet_rsk(req)->acked)) {
730 unsigned long timeo;
731
732 if (req->num_timeout++ == 0)
733 atomic_dec(&queue->young);
734 timeo = min(TCP_TIMEOUT_INIT << req->num_timeout, TCP_RTO_MAX);
735 mod_timer(&req->rsk_timer, jiffies + timeo);
736 return;
737 }
738drop:
739 inet_csk_reqsk_queue_drop_and_put(sk_listener, req);
740}
741
742static void reqsk_queue_hash_req(struct request_sock *req,
743 unsigned long timeout)
744{
745 req->num_retrans = 0;
746 req->num_timeout = 0;
747 req->sk = NULL;
748
749 timer_setup(&req->rsk_timer, reqsk_timer_handler, TIMER_PINNED);
750 mod_timer(&req->rsk_timer, jiffies + timeout);
751
752 inet_ehash_insert(req_to_sk(req), NULL);
753 /* before letting lookups find us, make sure all req fields
754 * are committed to memory and refcnt initialized.
755 */
756 smp_wmb();
757 refcount_set(&req->rsk_refcnt, 2 + 1);
758}
759
760void inet_csk_reqsk_queue_hash_add(struct sock *sk, struct request_sock *req,
761 unsigned long timeout)
762{
763 reqsk_queue_hash_req(req, timeout);
764 inet_csk_reqsk_queue_added(sk);
765}
766EXPORT_SYMBOL_GPL(inet_csk_reqsk_queue_hash_add);
767
768/**
769 * inet_csk_clone_lock - clone an inet socket, and lock its clone
770 * @sk: the socket to clone
771 * @req: request_sock
772 * @priority: for allocation (%GFP_KERNEL, %GFP_ATOMIC, etc)
773 *
774 * Caller must unlock socket even in error path (bh_unlock_sock(newsk))
775 */
776struct sock *inet_csk_clone_lock(const struct sock *sk,
777 const struct request_sock *req,
778 const gfp_t priority)
779{
780 struct sock *newsk = sk_clone_lock(sk, priority);
781
782 if (newsk) {
783 struct inet_connection_sock *newicsk = inet_csk(newsk);
784
785 inet_sk_set_state(newsk, TCP_SYN_RECV);
786 newicsk->icsk_bind_hash = NULL;
787
788 inet_sk(newsk)->inet_dport = inet_rsk(req)->ir_rmt_port;
789 inet_sk(newsk)->inet_num = inet_rsk(req)->ir_num;
790 inet_sk(newsk)->inet_sport = htons(inet_rsk(req)->ir_num);
791
792 /* listeners have SOCK_RCU_FREE, not the children */
793 sock_reset_flag(newsk, SOCK_RCU_FREE);
794
795 inet_sk(newsk)->mc_list = NULL;
796
797 newsk->sk_mark = inet_rsk(req)->ir_mark;
798 atomic64_set(&newsk->sk_cookie,
799 atomic64_read(&inet_rsk(req)->ir_cookie));
800
801 newicsk->icsk_retransmits = 0;
802 newicsk->icsk_backoff = 0;
803 newicsk->icsk_probes_out = 0;
804
805 /* Deinitialize accept_queue to trap illegal accesses. */
806 memset(&newicsk->icsk_accept_queue, 0, sizeof(newicsk->icsk_accept_queue));
807
808 security_inet_csk_clone(newsk, req);
809 }
810 return newsk;
811}
812EXPORT_SYMBOL_GPL(inet_csk_clone_lock);
813
814/*
815 * At this point, there should be no process reference to this
816 * socket, and thus no user references at all. Therefore we
817 * can assume the socket waitqueue is inactive and nobody will
818 * try to jump onto it.
819 */
820void inet_csk_destroy_sock(struct sock *sk)
821{
822 WARN_ON(sk->sk_state != TCP_CLOSE);
823 WARN_ON(!sock_flag(sk, SOCK_DEAD));
824
825 /* It cannot be in hash table! */
826 WARN_ON(!sk_unhashed(sk));
827
828 /* If it has not 0 inet_sk(sk)->inet_num, it must be bound */
829 WARN_ON(inet_sk(sk)->inet_num && !inet_csk(sk)->icsk_bind_hash);
830
831 sk->sk_prot->destroy(sk);
832
833 sk_stream_kill_queues(sk);
834
835 xfrm_sk_free_policy(sk);
836
837 sk_refcnt_debug_release(sk);
838
839 percpu_counter_dec(sk->sk_prot->orphan_count);
840
841 sock_put(sk);
842}
843EXPORT_SYMBOL(inet_csk_destroy_sock);
844
845/* This function allows to force a closure of a socket after the call to
846 * tcp/dccp_create_openreq_child().
847 */
848void inet_csk_prepare_forced_close(struct sock *sk)
849 __releases(&sk->sk_lock.slock)
850{
851 /* sk_clone_lock locked the socket and set refcnt to 2 */
852 bh_unlock_sock(sk);
853 sock_put(sk);
854
855 /* The below has to be done to allow calling inet_csk_destroy_sock */
856 sock_set_flag(sk, SOCK_DEAD);
857 percpu_counter_inc(sk->sk_prot->orphan_count);
858 inet_sk(sk)->inet_num = 0;
859}
860EXPORT_SYMBOL(inet_csk_prepare_forced_close);
861
862int inet_csk_listen_start(struct sock *sk, int backlog)
863{
864 struct inet_connection_sock *icsk = inet_csk(sk);
865 struct inet_sock *inet = inet_sk(sk);
866 int err = -EADDRINUSE;
867
868 reqsk_queue_alloc(&icsk->icsk_accept_queue);
869
870 sk->sk_max_ack_backlog = backlog;
871 sk->sk_ack_backlog = 0;
872 inet_csk_delack_init(sk);
873
874 /* There is race window here: we announce ourselves listening,
875 * but this transition is still not validated by get_port().
876 * It is OK, because this socket enters to hash table only
877 * after validation is complete.
878 */
879 inet_sk_state_store(sk, TCP_LISTEN);
880 if (!sk->sk_prot->get_port(sk, inet->inet_num)) {
881 inet->inet_sport = htons(inet->inet_num);
882
883 sk_dst_reset(sk);
884 err = sk->sk_prot->hash(sk);
885
886 if (likely(!err))
887 return 0;
888 }
889
890 inet_sk_set_state(sk, TCP_CLOSE);
891 return err;
892}
893EXPORT_SYMBOL_GPL(inet_csk_listen_start);
894
895static void inet_child_forget(struct sock *sk, struct request_sock *req,
896 struct sock *child)
897{
898 sk->sk_prot->disconnect(child, O_NONBLOCK);
899
900 sock_orphan(child);
901
902 percpu_counter_inc(sk->sk_prot->orphan_count);
903
904 if (sk->sk_protocol == IPPROTO_TCP && tcp_rsk(req)->tfo_listener) {
905 BUG_ON(tcp_sk(child)->fastopen_rsk != req);
906 BUG_ON(sk != req->rsk_listener);
907
908 /* Paranoid, to prevent race condition if
909 * an inbound pkt destined for child is
910 * blocked by sock lock in tcp_v4_rcv().
911 * Also to satisfy an assertion in
912 * tcp_v4_destroy_sock().
913 */
914 tcp_sk(child)->fastopen_rsk = NULL;
915 }
916 inet_csk_destroy_sock(child);
917}
918
919struct sock *inet_csk_reqsk_queue_add(struct sock *sk,
920 struct request_sock *req,
921 struct sock *child)
922{
923 struct request_sock_queue *queue = &inet_csk(sk)->icsk_accept_queue;
924
925 spin_lock(&queue->rskq_lock);
926 if (unlikely(sk->sk_state != TCP_LISTEN)) {
927 inet_child_forget(sk, req, child);
928 child = NULL;
929 } else {
930 req->sk = child;
931 req->dl_next = NULL;
932 if (queue->rskq_accept_head == NULL)
933 queue->rskq_accept_head = req;
934 else
935 queue->rskq_accept_tail->dl_next = req;
936 queue->rskq_accept_tail = req;
937 sk_acceptq_added(sk);
938 }
939 spin_unlock(&queue->rskq_lock);
940 return child;
941}
942EXPORT_SYMBOL(inet_csk_reqsk_queue_add);
943
944struct sock *inet_csk_complete_hashdance(struct sock *sk, struct sock *child,
945 struct request_sock *req, bool own_req)
946{
947 if (own_req) {
948 inet_csk_reqsk_queue_drop(sk, req);
949 reqsk_queue_removed(&inet_csk(sk)->icsk_accept_queue, req);
950 if (inet_csk_reqsk_queue_add(sk, req, child))
951 return child;
952 }
953 /* Too bad, another child took ownership of the request, undo. */
954 bh_unlock_sock(child);
955 sock_put(child);
956 return NULL;
957}
958EXPORT_SYMBOL(inet_csk_complete_hashdance);
959
960/*
961 * This routine closes sockets which have been at least partially
962 * opened, but not yet accepted.
963 */
964void inet_csk_listen_stop(struct sock *sk)
965{
966 struct inet_connection_sock *icsk = inet_csk(sk);
967 struct request_sock_queue *queue = &icsk->icsk_accept_queue;
968 struct request_sock *next, *req;
969
970 /* Following specs, it would be better either to send FIN
971 * (and enter FIN-WAIT-1, it is normal close)
972 * or to send active reset (abort).
973 * Certainly, it is pretty dangerous while synflood, but it is
974 * bad justification for our negligence 8)
975 * To be honest, we are not able to make either
976 * of the variants now. --ANK
977 */
978 while ((req = reqsk_queue_remove(queue, sk)) != NULL) {
979 struct sock *child = req->sk;
980
981 local_bh_disable();
982 bh_lock_sock(child);
983 WARN_ON(sock_owned_by_user(child));
984 sock_hold(child);
985
986 inet_child_forget(sk, req, child);
987 reqsk_put(req);
988 bh_unlock_sock(child);
989 local_bh_enable();
990 sock_put(child);
991
992 cond_resched();
993 }
994 if (queue->fastopenq.rskq_rst_head) {
995 /* Free all the reqs queued in rskq_rst_head. */
996 spin_lock_bh(&queue->fastopenq.lock);
997 req = queue->fastopenq.rskq_rst_head;
998 queue->fastopenq.rskq_rst_head = NULL;
999 spin_unlock_bh(&queue->fastopenq.lock);
1000 while (req != NULL) {
1001 next = req->dl_next;
1002 reqsk_put(req);
1003 req = next;
1004 }
1005 }
1006 WARN_ON_ONCE(sk->sk_ack_backlog);
1007}
1008EXPORT_SYMBOL_GPL(inet_csk_listen_stop);
1009
1010void inet_csk_addr2sockaddr(struct sock *sk, struct sockaddr *uaddr)
1011{
1012 struct sockaddr_in *sin = (struct sockaddr_in *)uaddr;
1013 const struct inet_sock *inet = inet_sk(sk);
1014
1015 sin->sin_family = AF_INET;
1016 sin->sin_addr.s_addr = inet->inet_daddr;
1017 sin->sin_port = inet->inet_dport;
1018}
1019EXPORT_SYMBOL_GPL(inet_csk_addr2sockaddr);
1020
1021#ifdef CONFIG_COMPAT
1022int inet_csk_compat_getsockopt(struct sock *sk, int level, int optname,
1023 char __user *optval, int __user *optlen)
1024{
1025 const struct inet_connection_sock *icsk = inet_csk(sk);
1026
1027 if (icsk->icsk_af_ops->compat_getsockopt)
1028 return icsk->icsk_af_ops->compat_getsockopt(sk, level, optname,
1029 optval, optlen);
1030 return icsk->icsk_af_ops->getsockopt(sk, level, optname,
1031 optval, optlen);
1032}
1033EXPORT_SYMBOL_GPL(inet_csk_compat_getsockopt);
1034
1035int inet_csk_compat_setsockopt(struct sock *sk, int level, int optname,
1036 char __user *optval, unsigned int optlen)
1037{
1038 const struct inet_connection_sock *icsk = inet_csk(sk);
1039
1040 if (icsk->icsk_af_ops->compat_setsockopt)
1041 return icsk->icsk_af_ops->compat_setsockopt(sk, level, optname,
1042 optval, optlen);
1043 return icsk->icsk_af_ops->setsockopt(sk, level, optname,
1044 optval, optlen);
1045}
1046EXPORT_SYMBOL_GPL(inet_csk_compat_setsockopt);
1047#endif
1048
1049static struct dst_entry *inet_csk_rebuild_route(struct sock *sk, struct flowi *fl)
1050{
1051 const struct inet_sock *inet = inet_sk(sk);
1052 const struct ip_options_rcu *inet_opt;
1053 __be32 daddr = inet->inet_daddr;
1054 struct flowi4 *fl4;
1055 struct rtable *rt;
1056
1057 rcu_read_lock();
1058 inet_opt = rcu_dereference(inet->inet_opt);
1059 if (inet_opt && inet_opt->opt.srr)
1060 daddr = inet_opt->opt.faddr;
1061 fl4 = &fl->u.ip4;
1062 rt = ip_route_output_ports(sock_net(sk), fl4, sk, daddr,
1063 inet->inet_saddr, inet->inet_dport,
1064 inet->inet_sport, sk->sk_protocol,
1065 RT_CONN_FLAGS(sk), sk->sk_bound_dev_if);
1066 if (IS_ERR(rt))
1067 rt = NULL;
1068 if (rt)
1069 sk_setup_caps(sk, &rt->dst);
1070 rcu_read_unlock();
1071
1072 return &rt->dst;
1073}
1074
1075struct dst_entry *inet_csk_update_pmtu(struct sock *sk, u32 mtu)
1076{
1077 struct dst_entry *dst = __sk_dst_check(sk, 0);
1078 struct inet_sock *inet = inet_sk(sk);
1079
1080 if (!dst) {
1081 dst = inet_csk_rebuild_route(sk, &inet->cork.fl);
1082 if (!dst)
1083 goto out;
1084 }
1085 dst->ops->update_pmtu(dst, sk, NULL, mtu);
1086
1087 dst = __sk_dst_check(sk, 0);
1088 if (!dst)
1089 dst = inet_csk_rebuild_route(sk, &inet->cork.fl);
1090out:
1091 return dst;
1092}
1093EXPORT_SYMBOL_GPL(inet_csk_update_pmtu);
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 * Support for INET connection oriented protocols.
8 *
9 * Authors: See the TCP sources
10 */
11
12#include <linux/module.h>
13#include <linux/jhash.h>
14
15#include <net/inet_connection_sock.h>
16#include <net/inet_hashtables.h>
17#include <net/inet_timewait_sock.h>
18#include <net/ip.h>
19#include <net/route.h>
20#include <net/tcp_states.h>
21#include <net/xfrm.h>
22#include <net/tcp.h>
23#include <net/sock_reuseport.h>
24#include <net/addrconf.h>
25
26#if IS_ENABLED(CONFIG_IPV6)
27/* match_sk*_wildcard == true: IPV6_ADDR_ANY equals to any IPv6 addresses
28 * if IPv6 only, and any IPv4 addresses
29 * if not IPv6 only
30 * match_sk*_wildcard == false: addresses must be exactly the same, i.e.
31 * IPV6_ADDR_ANY only equals to IPV6_ADDR_ANY,
32 * and 0.0.0.0 equals to 0.0.0.0 only
33 */
34static bool ipv6_rcv_saddr_equal(const struct in6_addr *sk1_rcv_saddr6,
35 const struct in6_addr *sk2_rcv_saddr6,
36 __be32 sk1_rcv_saddr, __be32 sk2_rcv_saddr,
37 bool sk1_ipv6only, bool sk2_ipv6only,
38 bool match_sk1_wildcard,
39 bool match_sk2_wildcard)
40{
41 int addr_type = ipv6_addr_type(sk1_rcv_saddr6);
42 int addr_type2 = sk2_rcv_saddr6 ? ipv6_addr_type(sk2_rcv_saddr6) : IPV6_ADDR_MAPPED;
43
44 /* if both are mapped, treat as IPv4 */
45 if (addr_type == IPV6_ADDR_MAPPED && addr_type2 == IPV6_ADDR_MAPPED) {
46 if (!sk2_ipv6only) {
47 if (sk1_rcv_saddr == sk2_rcv_saddr)
48 return true;
49 return (match_sk1_wildcard && !sk1_rcv_saddr) ||
50 (match_sk2_wildcard && !sk2_rcv_saddr);
51 }
52 return false;
53 }
54
55 if (addr_type == IPV6_ADDR_ANY && addr_type2 == IPV6_ADDR_ANY)
56 return true;
57
58 if (addr_type2 == IPV6_ADDR_ANY && match_sk2_wildcard &&
59 !(sk2_ipv6only && addr_type == IPV6_ADDR_MAPPED))
60 return true;
61
62 if (addr_type == IPV6_ADDR_ANY && match_sk1_wildcard &&
63 !(sk1_ipv6only && addr_type2 == IPV6_ADDR_MAPPED))
64 return true;
65
66 if (sk2_rcv_saddr6 &&
67 ipv6_addr_equal(sk1_rcv_saddr6, sk2_rcv_saddr6))
68 return true;
69
70 return false;
71}
72#endif
73
74/* match_sk*_wildcard == true: 0.0.0.0 equals to any IPv4 addresses
75 * match_sk*_wildcard == false: addresses must be exactly the same, i.e.
76 * 0.0.0.0 only equals to 0.0.0.0
77 */
78static bool ipv4_rcv_saddr_equal(__be32 sk1_rcv_saddr, __be32 sk2_rcv_saddr,
79 bool sk2_ipv6only, bool match_sk1_wildcard,
80 bool match_sk2_wildcard)
81{
82 if (!sk2_ipv6only) {
83 if (sk1_rcv_saddr == sk2_rcv_saddr)
84 return true;
85 return (match_sk1_wildcard && !sk1_rcv_saddr) ||
86 (match_sk2_wildcard && !sk2_rcv_saddr);
87 }
88 return false;
89}
90
91bool inet_rcv_saddr_equal(const struct sock *sk, const struct sock *sk2,
92 bool match_wildcard)
93{
94#if IS_ENABLED(CONFIG_IPV6)
95 if (sk->sk_family == AF_INET6)
96 return ipv6_rcv_saddr_equal(&sk->sk_v6_rcv_saddr,
97 inet6_rcv_saddr(sk2),
98 sk->sk_rcv_saddr,
99 sk2->sk_rcv_saddr,
100 ipv6_only_sock(sk),
101 ipv6_only_sock(sk2),
102 match_wildcard,
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 match_wildcard);
108}
109EXPORT_SYMBOL(inet_rcv_saddr_equal);
110
111bool inet_rcv_saddr_any(const struct sock *sk)
112{
113#if IS_ENABLED(CONFIG_IPV6)
114 if (sk->sk_family == AF_INET6)
115 return ipv6_addr_any(&sk->sk_v6_rcv_saddr);
116#endif
117 return !sk->sk_rcv_saddr;
118}
119
120void inet_get_local_port_range(struct net *net, int *low, int *high)
121{
122 unsigned int seq;
123
124 do {
125 seq = read_seqbegin(&net->ipv4.ip_local_ports.lock);
126
127 *low = net->ipv4.ip_local_ports.range[0];
128 *high = net->ipv4.ip_local_ports.range[1];
129 } while (read_seqretry(&net->ipv4.ip_local_ports.lock, seq));
130}
131EXPORT_SYMBOL(inet_get_local_port_range);
132
133static int inet_csk_bind_conflict(const struct sock *sk,
134 const struct inet_bind_bucket *tb,
135 bool relax, bool reuseport_ok)
136{
137 struct sock *sk2;
138 bool reuseport_cb_ok;
139 bool reuse = sk->sk_reuse;
140 bool reuseport = !!sk->sk_reuseport;
141 struct sock_reuseport *reuseport_cb;
142 kuid_t uid = sock_i_uid((struct sock *)sk);
143
144 rcu_read_lock();
145 reuseport_cb = rcu_dereference(sk->sk_reuseport_cb);
146 /* paired with WRITE_ONCE() in __reuseport_(add|detach)_closed_sock */
147 reuseport_cb_ok = !reuseport_cb || READ_ONCE(reuseport_cb->num_closed_socks);
148 rcu_read_unlock();
149
150 /*
151 * Unlike other sk lookup places we do not check
152 * for sk_net here, since _all_ the socks listed
153 * in tb->owners list belong to the same net - the
154 * one this bucket belongs to.
155 */
156
157 sk_for_each_bound(sk2, &tb->owners) {
158 if (sk != sk2 &&
159 (!sk->sk_bound_dev_if ||
160 !sk2->sk_bound_dev_if ||
161 sk->sk_bound_dev_if == sk2->sk_bound_dev_if)) {
162 if (reuse && sk2->sk_reuse &&
163 sk2->sk_state != TCP_LISTEN) {
164 if ((!relax ||
165 (!reuseport_ok &&
166 reuseport && sk2->sk_reuseport &&
167 reuseport_cb_ok &&
168 (sk2->sk_state == TCP_TIME_WAIT ||
169 uid_eq(uid, sock_i_uid(sk2))))) &&
170 inet_rcv_saddr_equal(sk, sk2, true))
171 break;
172 } else if (!reuseport_ok ||
173 !reuseport || !sk2->sk_reuseport ||
174 !reuseport_cb_ok ||
175 (sk2->sk_state != TCP_TIME_WAIT &&
176 !uid_eq(uid, sock_i_uid(sk2)))) {
177 if (inet_rcv_saddr_equal(sk, sk2, true))
178 break;
179 }
180 }
181 }
182 return sk2 != NULL;
183}
184
185/*
186 * Find an open port number for the socket. Returns with the
187 * inet_bind_hashbucket lock held.
188 */
189static struct inet_bind_hashbucket *
190inet_csk_find_open_port(struct sock *sk, struct inet_bind_bucket **tb_ret, int *port_ret)
191{
192 struct inet_hashinfo *hinfo = sk->sk_prot->h.hashinfo;
193 int port = 0;
194 struct inet_bind_hashbucket *head;
195 struct net *net = sock_net(sk);
196 bool relax = false;
197 int i, low, high, attempt_half;
198 struct inet_bind_bucket *tb;
199 u32 remaining, offset;
200 int l3mdev;
201
202 l3mdev = inet_sk_bound_l3mdev(sk);
203ports_exhausted:
204 attempt_half = (sk->sk_reuse == SK_CAN_REUSE) ? 1 : 0;
205other_half_scan:
206 inet_get_local_port_range(net, &low, &high);
207 high++; /* [32768, 60999] -> [32768, 61000[ */
208 if (high - low < 4)
209 attempt_half = 0;
210 if (attempt_half) {
211 int half = low + (((high - low) >> 2) << 1);
212
213 if (attempt_half == 1)
214 high = half;
215 else
216 low = half;
217 }
218 remaining = high - low;
219 if (likely(remaining > 1))
220 remaining &= ~1U;
221
222 offset = prandom_u32() % remaining;
223 /* __inet_hash_connect() favors ports having @low parity
224 * We do the opposite to not pollute connect() users.
225 */
226 offset |= 1U;
227
228other_parity_scan:
229 port = low + offset;
230 for (i = 0; i < remaining; i += 2, port += 2) {
231 if (unlikely(port >= high))
232 port -= remaining;
233 if (inet_is_local_reserved_port(net, port))
234 continue;
235 head = &hinfo->bhash[inet_bhashfn(net, port,
236 hinfo->bhash_size)];
237 spin_lock_bh(&head->lock);
238 inet_bind_bucket_for_each(tb, &head->chain)
239 if (net_eq(ib_net(tb), net) && tb->l3mdev == l3mdev &&
240 tb->port == port) {
241 if (!inet_csk_bind_conflict(sk, tb, relax, false))
242 goto success;
243 goto next_port;
244 }
245 tb = NULL;
246 goto success;
247next_port:
248 spin_unlock_bh(&head->lock);
249 cond_resched();
250 }
251
252 offset--;
253 if (!(offset & 1))
254 goto other_parity_scan;
255
256 if (attempt_half == 1) {
257 /* OK we now try the upper half of the range */
258 attempt_half = 2;
259 goto other_half_scan;
260 }
261
262 if (net->ipv4.sysctl_ip_autobind_reuse && !relax) {
263 /* We still have a chance to connect to different destinations */
264 relax = true;
265 goto ports_exhausted;
266 }
267 return NULL;
268success:
269 *port_ret = port;
270 *tb_ret = tb;
271 return head;
272}
273
274static inline int sk_reuseport_match(struct inet_bind_bucket *tb,
275 struct sock *sk)
276{
277 kuid_t uid = sock_i_uid(sk);
278
279 if (tb->fastreuseport <= 0)
280 return 0;
281 if (!sk->sk_reuseport)
282 return 0;
283 if (rcu_access_pointer(sk->sk_reuseport_cb))
284 return 0;
285 if (!uid_eq(tb->fastuid, uid))
286 return 0;
287 /* We only need to check the rcv_saddr if this tb was once marked
288 * without fastreuseport and then was reset, as we can only know that
289 * the fast_*rcv_saddr doesn't have any conflicts with the socks on the
290 * owners list.
291 */
292 if (tb->fastreuseport == FASTREUSEPORT_ANY)
293 return 1;
294#if IS_ENABLED(CONFIG_IPV6)
295 if (tb->fast_sk_family == AF_INET6)
296 return ipv6_rcv_saddr_equal(&tb->fast_v6_rcv_saddr,
297 inet6_rcv_saddr(sk),
298 tb->fast_rcv_saddr,
299 sk->sk_rcv_saddr,
300 tb->fast_ipv6_only,
301 ipv6_only_sock(sk), true, false);
302#endif
303 return ipv4_rcv_saddr_equal(tb->fast_rcv_saddr, sk->sk_rcv_saddr,
304 ipv6_only_sock(sk), true, false);
305}
306
307void inet_csk_update_fastreuse(struct inet_bind_bucket *tb,
308 struct sock *sk)
309{
310 kuid_t uid = sock_i_uid(sk);
311 bool reuse = sk->sk_reuse && sk->sk_state != TCP_LISTEN;
312
313 if (hlist_empty(&tb->owners)) {
314 tb->fastreuse = reuse;
315 if (sk->sk_reuseport) {
316 tb->fastreuseport = FASTREUSEPORT_ANY;
317 tb->fastuid = uid;
318 tb->fast_rcv_saddr = sk->sk_rcv_saddr;
319 tb->fast_ipv6_only = ipv6_only_sock(sk);
320 tb->fast_sk_family = sk->sk_family;
321#if IS_ENABLED(CONFIG_IPV6)
322 tb->fast_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
323#endif
324 } else {
325 tb->fastreuseport = 0;
326 }
327 } else {
328 if (!reuse)
329 tb->fastreuse = 0;
330 if (sk->sk_reuseport) {
331 /* We didn't match or we don't have fastreuseport set on
332 * the tb, but we have sk_reuseport set on this socket
333 * and we know that there are no bind conflicts with
334 * this socket in this tb, so reset our tb's reuseport
335 * settings so that any subsequent sockets that match
336 * our current socket will be put on the fast path.
337 *
338 * If we reset we need to set FASTREUSEPORT_STRICT so we
339 * do extra checking for all subsequent sk_reuseport
340 * socks.
341 */
342 if (!sk_reuseport_match(tb, sk)) {
343 tb->fastreuseport = FASTREUSEPORT_STRICT;
344 tb->fastuid = uid;
345 tb->fast_rcv_saddr = sk->sk_rcv_saddr;
346 tb->fast_ipv6_only = ipv6_only_sock(sk);
347 tb->fast_sk_family = sk->sk_family;
348#if IS_ENABLED(CONFIG_IPV6)
349 tb->fast_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
350#endif
351 }
352 } else {
353 tb->fastreuseport = 0;
354 }
355 }
356}
357
358/* Obtain a reference to a local port for the given sock,
359 * if snum is zero it means select any available local port.
360 * We try to allocate an odd port (and leave even ports for connect())
361 */
362int inet_csk_get_port(struct sock *sk, unsigned short snum)
363{
364 bool reuse = sk->sk_reuse && sk->sk_state != TCP_LISTEN;
365 struct inet_hashinfo *hinfo = sk->sk_prot->h.hashinfo;
366 int ret = 1, port = snum;
367 struct inet_bind_hashbucket *head;
368 struct net *net = sock_net(sk);
369 struct inet_bind_bucket *tb = NULL;
370 int l3mdev;
371
372 l3mdev = inet_sk_bound_l3mdev(sk);
373
374 if (!port) {
375 head = inet_csk_find_open_port(sk, &tb, &port);
376 if (!head)
377 return ret;
378 if (!tb)
379 goto tb_not_found;
380 goto success;
381 }
382 head = &hinfo->bhash[inet_bhashfn(net, port,
383 hinfo->bhash_size)];
384 spin_lock_bh(&head->lock);
385 inet_bind_bucket_for_each(tb, &head->chain)
386 if (net_eq(ib_net(tb), net) && tb->l3mdev == l3mdev &&
387 tb->port == port)
388 goto tb_found;
389tb_not_found:
390 tb = inet_bind_bucket_create(hinfo->bind_bucket_cachep,
391 net, head, port, l3mdev);
392 if (!tb)
393 goto fail_unlock;
394tb_found:
395 if (!hlist_empty(&tb->owners)) {
396 if (sk->sk_reuse == SK_FORCE_REUSE)
397 goto success;
398
399 if ((tb->fastreuse > 0 && reuse) ||
400 sk_reuseport_match(tb, sk))
401 goto success;
402 if (inet_csk_bind_conflict(sk, tb, true, true))
403 goto fail_unlock;
404 }
405success:
406 inet_csk_update_fastreuse(tb, sk);
407
408 if (!inet_csk(sk)->icsk_bind_hash)
409 inet_bind_hash(sk, tb, port);
410 WARN_ON(inet_csk(sk)->icsk_bind_hash != tb);
411 ret = 0;
412
413fail_unlock:
414 spin_unlock_bh(&head->lock);
415 return ret;
416}
417EXPORT_SYMBOL_GPL(inet_csk_get_port);
418
419/*
420 * Wait for an incoming connection, avoid race conditions. This must be called
421 * with the socket locked.
422 */
423static int inet_csk_wait_for_connect(struct sock *sk, long timeo)
424{
425 struct inet_connection_sock *icsk = inet_csk(sk);
426 DEFINE_WAIT(wait);
427 int err;
428
429 /*
430 * True wake-one mechanism for incoming connections: only
431 * one process gets woken up, not the 'whole herd'.
432 * Since we do not 'race & poll' for established sockets
433 * anymore, the common case will execute the loop only once.
434 *
435 * Subtle issue: "add_wait_queue_exclusive()" will be added
436 * after any current non-exclusive waiters, and we know that
437 * it will always _stay_ after any new non-exclusive waiters
438 * because all non-exclusive waiters are added at the
439 * beginning of the wait-queue. As such, it's ok to "drop"
440 * our exclusiveness temporarily when we get woken up without
441 * having to remove and re-insert us on the wait queue.
442 */
443 for (;;) {
444 prepare_to_wait_exclusive(sk_sleep(sk), &wait,
445 TASK_INTERRUPTIBLE);
446 release_sock(sk);
447 if (reqsk_queue_empty(&icsk->icsk_accept_queue))
448 timeo = schedule_timeout(timeo);
449 sched_annotate_sleep();
450 lock_sock(sk);
451 err = 0;
452 if (!reqsk_queue_empty(&icsk->icsk_accept_queue))
453 break;
454 err = -EINVAL;
455 if (sk->sk_state != TCP_LISTEN)
456 break;
457 err = sock_intr_errno(timeo);
458 if (signal_pending(current))
459 break;
460 err = -EAGAIN;
461 if (!timeo)
462 break;
463 }
464 finish_wait(sk_sleep(sk), &wait);
465 return err;
466}
467
468/*
469 * This will accept the next outstanding connection.
470 */
471struct sock *inet_csk_accept(struct sock *sk, int flags, int *err, bool kern)
472{
473 struct inet_connection_sock *icsk = inet_csk(sk);
474 struct request_sock_queue *queue = &icsk->icsk_accept_queue;
475 struct request_sock *req;
476 struct sock *newsk;
477 int error;
478
479 lock_sock(sk);
480
481 /* We need to make sure that this socket is listening,
482 * and that it has something pending.
483 */
484 error = -EINVAL;
485 if (sk->sk_state != TCP_LISTEN)
486 goto out_err;
487
488 /* Find already established connection */
489 if (reqsk_queue_empty(queue)) {
490 long timeo = sock_rcvtimeo(sk, flags & O_NONBLOCK);
491
492 /* If this is a non blocking socket don't sleep */
493 error = -EAGAIN;
494 if (!timeo)
495 goto out_err;
496
497 error = inet_csk_wait_for_connect(sk, timeo);
498 if (error)
499 goto out_err;
500 }
501 req = reqsk_queue_remove(queue, sk);
502 newsk = req->sk;
503
504 if (sk->sk_protocol == IPPROTO_TCP &&
505 tcp_rsk(req)->tfo_listener) {
506 spin_lock_bh(&queue->fastopenq.lock);
507 if (tcp_rsk(req)->tfo_listener) {
508 /* We are still waiting for the final ACK from 3WHS
509 * so can't free req now. Instead, we set req->sk to
510 * NULL to signify that the child socket is taken
511 * so reqsk_fastopen_remove() will free the req
512 * when 3WHS finishes (or is aborted).
513 */
514 req->sk = NULL;
515 req = NULL;
516 }
517 spin_unlock_bh(&queue->fastopenq.lock);
518 }
519
520out:
521 release_sock(sk);
522 if (newsk && mem_cgroup_sockets_enabled) {
523 int amt;
524
525 /* atomically get the memory usage, set and charge the
526 * newsk->sk_memcg.
527 */
528 lock_sock(newsk);
529
530 /* The socket has not been accepted yet, no need to look at
531 * newsk->sk_wmem_queued.
532 */
533 amt = sk_mem_pages(newsk->sk_forward_alloc +
534 atomic_read(&newsk->sk_rmem_alloc));
535 mem_cgroup_sk_alloc(newsk);
536 if (newsk->sk_memcg && amt)
537 mem_cgroup_charge_skmem(newsk->sk_memcg, amt);
538
539 release_sock(newsk);
540 }
541 if (req)
542 reqsk_put(req);
543 return newsk;
544out_err:
545 newsk = NULL;
546 req = NULL;
547 *err = error;
548 goto out;
549}
550EXPORT_SYMBOL(inet_csk_accept);
551
552/*
553 * Using different timers for retransmit, delayed acks and probes
554 * We may wish use just one timer maintaining a list of expire jiffies
555 * to optimize.
556 */
557void inet_csk_init_xmit_timers(struct sock *sk,
558 void (*retransmit_handler)(struct timer_list *t),
559 void (*delack_handler)(struct timer_list *t),
560 void (*keepalive_handler)(struct timer_list *t))
561{
562 struct inet_connection_sock *icsk = inet_csk(sk);
563
564 timer_setup(&icsk->icsk_retransmit_timer, retransmit_handler, 0);
565 timer_setup(&icsk->icsk_delack_timer, delack_handler, 0);
566 timer_setup(&sk->sk_timer, keepalive_handler, 0);
567 icsk->icsk_pending = icsk->icsk_ack.pending = 0;
568}
569EXPORT_SYMBOL(inet_csk_init_xmit_timers);
570
571void inet_csk_clear_xmit_timers(struct sock *sk)
572{
573 struct inet_connection_sock *icsk = inet_csk(sk);
574
575 icsk->icsk_pending = icsk->icsk_ack.pending = 0;
576
577 sk_stop_timer(sk, &icsk->icsk_retransmit_timer);
578 sk_stop_timer(sk, &icsk->icsk_delack_timer);
579 sk_stop_timer(sk, &sk->sk_timer);
580}
581EXPORT_SYMBOL(inet_csk_clear_xmit_timers);
582
583void inet_csk_delete_keepalive_timer(struct sock *sk)
584{
585 sk_stop_timer(sk, &sk->sk_timer);
586}
587EXPORT_SYMBOL(inet_csk_delete_keepalive_timer);
588
589void inet_csk_reset_keepalive_timer(struct sock *sk, unsigned long len)
590{
591 sk_reset_timer(sk, &sk->sk_timer, jiffies + len);
592}
593EXPORT_SYMBOL(inet_csk_reset_keepalive_timer);
594
595struct dst_entry *inet_csk_route_req(const struct sock *sk,
596 struct flowi4 *fl4,
597 const struct request_sock *req)
598{
599 const struct inet_request_sock *ireq = inet_rsk(req);
600 struct net *net = read_pnet(&ireq->ireq_net);
601 struct ip_options_rcu *opt;
602 struct rtable *rt;
603
604 rcu_read_lock();
605 opt = rcu_dereference(ireq->ireq_opt);
606
607 flowi4_init_output(fl4, ireq->ir_iif, ireq->ir_mark,
608 RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE,
609 sk->sk_protocol, inet_sk_flowi_flags(sk),
610 (opt && opt->opt.srr) ? opt->opt.faddr : ireq->ir_rmt_addr,
611 ireq->ir_loc_addr, ireq->ir_rmt_port,
612 htons(ireq->ir_num), sk->sk_uid);
613 security_req_classify_flow(req, flowi4_to_flowi_common(fl4));
614 rt = ip_route_output_flow(net, fl4, sk);
615 if (IS_ERR(rt))
616 goto no_route;
617 if (opt && opt->opt.is_strictroute && rt->rt_uses_gateway)
618 goto route_err;
619 rcu_read_unlock();
620 return &rt->dst;
621
622route_err:
623 ip_rt_put(rt);
624no_route:
625 rcu_read_unlock();
626 __IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
627 return NULL;
628}
629EXPORT_SYMBOL_GPL(inet_csk_route_req);
630
631struct dst_entry *inet_csk_route_child_sock(const struct sock *sk,
632 struct sock *newsk,
633 const struct request_sock *req)
634{
635 const struct inet_request_sock *ireq = inet_rsk(req);
636 struct net *net = read_pnet(&ireq->ireq_net);
637 struct inet_sock *newinet = inet_sk(newsk);
638 struct ip_options_rcu *opt;
639 struct flowi4 *fl4;
640 struct rtable *rt;
641
642 opt = rcu_dereference(ireq->ireq_opt);
643 fl4 = &newinet->cork.fl.u.ip4;
644
645 flowi4_init_output(fl4, ireq->ir_iif, ireq->ir_mark,
646 RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE,
647 sk->sk_protocol, inet_sk_flowi_flags(sk),
648 (opt && opt->opt.srr) ? opt->opt.faddr : ireq->ir_rmt_addr,
649 ireq->ir_loc_addr, ireq->ir_rmt_port,
650 htons(ireq->ir_num), sk->sk_uid);
651 security_req_classify_flow(req, flowi4_to_flowi_common(fl4));
652 rt = ip_route_output_flow(net, fl4, sk);
653 if (IS_ERR(rt))
654 goto no_route;
655 if (opt && opt->opt.is_strictroute && rt->rt_uses_gateway)
656 goto route_err;
657 return &rt->dst;
658
659route_err:
660 ip_rt_put(rt);
661no_route:
662 __IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
663 return NULL;
664}
665EXPORT_SYMBOL_GPL(inet_csk_route_child_sock);
666
667/* Decide when to expire the request and when to resend SYN-ACK */
668static void syn_ack_recalc(struct request_sock *req,
669 const int max_syn_ack_retries,
670 const u8 rskq_defer_accept,
671 int *expire, int *resend)
672{
673 if (!rskq_defer_accept) {
674 *expire = req->num_timeout >= max_syn_ack_retries;
675 *resend = 1;
676 return;
677 }
678 *expire = req->num_timeout >= max_syn_ack_retries &&
679 (!inet_rsk(req)->acked || req->num_timeout >= rskq_defer_accept);
680 /* Do not resend while waiting for data after ACK,
681 * start to resend on end of deferring period to give
682 * last chance for data or ACK to create established socket.
683 */
684 *resend = !inet_rsk(req)->acked ||
685 req->num_timeout >= rskq_defer_accept - 1;
686}
687
688int inet_rtx_syn_ack(const struct sock *parent, struct request_sock *req)
689{
690 int err = req->rsk_ops->rtx_syn_ack(parent, req);
691
692 if (!err)
693 req->num_retrans++;
694 return err;
695}
696EXPORT_SYMBOL(inet_rtx_syn_ack);
697
698static struct request_sock *inet_reqsk_clone(struct request_sock *req,
699 struct sock *sk)
700{
701 struct sock *req_sk, *nreq_sk;
702 struct request_sock *nreq;
703
704 nreq = kmem_cache_alloc(req->rsk_ops->slab, GFP_ATOMIC | __GFP_NOWARN);
705 if (!nreq) {
706 __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMIGRATEREQFAILURE);
707
708 /* paired with refcount_inc_not_zero() in reuseport_migrate_sock() */
709 sock_put(sk);
710 return NULL;
711 }
712
713 req_sk = req_to_sk(req);
714 nreq_sk = req_to_sk(nreq);
715
716 memcpy(nreq_sk, req_sk,
717 offsetof(struct sock, sk_dontcopy_begin));
718 memcpy(&nreq_sk->sk_dontcopy_end, &req_sk->sk_dontcopy_end,
719 req->rsk_ops->obj_size - offsetof(struct sock, sk_dontcopy_end));
720
721 sk_node_init(&nreq_sk->sk_node);
722 nreq_sk->sk_tx_queue_mapping = req_sk->sk_tx_queue_mapping;
723#ifdef CONFIG_XPS
724 nreq_sk->sk_rx_queue_mapping = req_sk->sk_rx_queue_mapping;
725#endif
726 nreq_sk->sk_incoming_cpu = req_sk->sk_incoming_cpu;
727
728 nreq->rsk_listener = sk;
729
730 /* We need not acquire fastopenq->lock
731 * because the child socket is locked in inet_csk_listen_stop().
732 */
733 if (sk->sk_protocol == IPPROTO_TCP && tcp_rsk(nreq)->tfo_listener)
734 rcu_assign_pointer(tcp_sk(nreq->sk)->fastopen_rsk, nreq);
735
736 return nreq;
737}
738
739static void reqsk_queue_migrated(struct request_sock_queue *queue,
740 const struct request_sock *req)
741{
742 if (req->num_timeout == 0)
743 atomic_inc(&queue->young);
744 atomic_inc(&queue->qlen);
745}
746
747static void reqsk_migrate_reset(struct request_sock *req)
748{
749 req->saved_syn = NULL;
750#if IS_ENABLED(CONFIG_IPV6)
751 inet_rsk(req)->ipv6_opt = NULL;
752 inet_rsk(req)->pktopts = NULL;
753#else
754 inet_rsk(req)->ireq_opt = NULL;
755#endif
756}
757
758/* return true if req was found in the ehash table */
759static bool reqsk_queue_unlink(struct request_sock *req)
760{
761 struct inet_hashinfo *hashinfo = req_to_sk(req)->sk_prot->h.hashinfo;
762 bool found = false;
763
764 if (sk_hashed(req_to_sk(req))) {
765 spinlock_t *lock = inet_ehash_lockp(hashinfo, req->rsk_hash);
766
767 spin_lock(lock);
768 found = __sk_nulls_del_node_init_rcu(req_to_sk(req));
769 spin_unlock(lock);
770 }
771 if (timer_pending(&req->rsk_timer) && del_timer_sync(&req->rsk_timer))
772 reqsk_put(req);
773 return found;
774}
775
776bool inet_csk_reqsk_queue_drop(struct sock *sk, struct request_sock *req)
777{
778 bool unlinked = reqsk_queue_unlink(req);
779
780 if (unlinked) {
781 reqsk_queue_removed(&inet_csk(sk)->icsk_accept_queue, req);
782 reqsk_put(req);
783 }
784 return unlinked;
785}
786EXPORT_SYMBOL(inet_csk_reqsk_queue_drop);
787
788void inet_csk_reqsk_queue_drop_and_put(struct sock *sk, struct request_sock *req)
789{
790 inet_csk_reqsk_queue_drop(sk, req);
791 reqsk_put(req);
792}
793EXPORT_SYMBOL(inet_csk_reqsk_queue_drop_and_put);
794
795static void reqsk_timer_handler(struct timer_list *t)
796{
797 struct request_sock *req = from_timer(req, t, rsk_timer);
798 struct request_sock *nreq = NULL, *oreq = req;
799 struct sock *sk_listener = req->rsk_listener;
800 struct inet_connection_sock *icsk;
801 struct request_sock_queue *queue;
802 struct net *net;
803 int max_syn_ack_retries, qlen, expire = 0, resend = 0;
804
805 if (inet_sk_state_load(sk_listener) != TCP_LISTEN) {
806 struct sock *nsk;
807
808 nsk = reuseport_migrate_sock(sk_listener, req_to_sk(req), NULL);
809 if (!nsk)
810 goto drop;
811
812 nreq = inet_reqsk_clone(req, nsk);
813 if (!nreq)
814 goto drop;
815
816 /* The new timer for the cloned req can decrease the 2
817 * by calling inet_csk_reqsk_queue_drop_and_put(), so
818 * hold another count to prevent use-after-free and
819 * call reqsk_put() just before return.
820 */
821 refcount_set(&nreq->rsk_refcnt, 2 + 1);
822 timer_setup(&nreq->rsk_timer, reqsk_timer_handler, TIMER_PINNED);
823 reqsk_queue_migrated(&inet_csk(nsk)->icsk_accept_queue, req);
824
825 req = nreq;
826 sk_listener = nsk;
827 }
828
829 icsk = inet_csk(sk_listener);
830 net = sock_net(sk_listener);
831 max_syn_ack_retries = icsk->icsk_syn_retries ? : net->ipv4.sysctl_tcp_synack_retries;
832 /* Normally all the openreqs are young and become mature
833 * (i.e. converted to established socket) for first timeout.
834 * If synack was not acknowledged for 1 second, it means
835 * one of the following things: synack was lost, ack was lost,
836 * rtt is high or nobody planned to ack (i.e. synflood).
837 * When server is a bit loaded, queue is populated with old
838 * open requests, reducing effective size of queue.
839 * When server is well loaded, queue size reduces to zero
840 * after several minutes of work. It is not synflood,
841 * it is normal operation. The solution is pruning
842 * too old entries overriding normal timeout, when
843 * situation becomes dangerous.
844 *
845 * Essentially, we reserve half of room for young
846 * embrions; and abort old ones without pity, if old
847 * ones are about to clog our table.
848 */
849 queue = &icsk->icsk_accept_queue;
850 qlen = reqsk_queue_len(queue);
851 if ((qlen << 1) > max(8U, READ_ONCE(sk_listener->sk_max_ack_backlog))) {
852 int young = reqsk_queue_len_young(queue) << 1;
853
854 while (max_syn_ack_retries > 2) {
855 if (qlen < young)
856 break;
857 max_syn_ack_retries--;
858 young <<= 1;
859 }
860 }
861 syn_ack_recalc(req, max_syn_ack_retries, READ_ONCE(queue->rskq_defer_accept),
862 &expire, &resend);
863 req->rsk_ops->syn_ack_timeout(req);
864 if (!expire &&
865 (!resend ||
866 !inet_rtx_syn_ack(sk_listener, req) ||
867 inet_rsk(req)->acked)) {
868 unsigned long timeo;
869
870 if (req->num_timeout++ == 0)
871 atomic_dec(&queue->young);
872 timeo = min(TCP_TIMEOUT_INIT << req->num_timeout, TCP_RTO_MAX);
873 mod_timer(&req->rsk_timer, jiffies + timeo);
874
875 if (!nreq)
876 return;
877
878 if (!inet_ehash_insert(req_to_sk(nreq), req_to_sk(oreq), NULL)) {
879 /* delete timer */
880 inet_csk_reqsk_queue_drop(sk_listener, nreq);
881 goto no_ownership;
882 }
883
884 __NET_INC_STATS(net, LINUX_MIB_TCPMIGRATEREQSUCCESS);
885 reqsk_migrate_reset(oreq);
886 reqsk_queue_removed(&inet_csk(oreq->rsk_listener)->icsk_accept_queue, oreq);
887 reqsk_put(oreq);
888
889 reqsk_put(nreq);
890 return;
891 }
892
893 /* Even if we can clone the req, we may need not retransmit any more
894 * SYN+ACKs (nreq->num_timeout > max_syn_ack_retries, etc), or another
895 * CPU may win the "own_req" race so that inet_ehash_insert() fails.
896 */
897 if (nreq) {
898 __NET_INC_STATS(net, LINUX_MIB_TCPMIGRATEREQFAILURE);
899no_ownership:
900 reqsk_migrate_reset(nreq);
901 reqsk_queue_removed(queue, nreq);
902 __reqsk_free(nreq);
903 }
904
905drop:
906 inet_csk_reqsk_queue_drop_and_put(oreq->rsk_listener, oreq);
907}
908
909static void reqsk_queue_hash_req(struct request_sock *req,
910 unsigned long timeout)
911{
912 timer_setup(&req->rsk_timer, reqsk_timer_handler, TIMER_PINNED);
913 mod_timer(&req->rsk_timer, jiffies + timeout);
914
915 inet_ehash_insert(req_to_sk(req), NULL, NULL);
916 /* before letting lookups find us, make sure all req fields
917 * are committed to memory and refcnt initialized.
918 */
919 smp_wmb();
920 refcount_set(&req->rsk_refcnt, 2 + 1);
921}
922
923void inet_csk_reqsk_queue_hash_add(struct sock *sk, struct request_sock *req,
924 unsigned long timeout)
925{
926 reqsk_queue_hash_req(req, timeout);
927 inet_csk_reqsk_queue_added(sk);
928}
929EXPORT_SYMBOL_GPL(inet_csk_reqsk_queue_hash_add);
930
931static void inet_clone_ulp(const struct request_sock *req, struct sock *newsk,
932 const gfp_t priority)
933{
934 struct inet_connection_sock *icsk = inet_csk(newsk);
935
936 if (!icsk->icsk_ulp_ops)
937 return;
938
939 if (icsk->icsk_ulp_ops->clone)
940 icsk->icsk_ulp_ops->clone(req, newsk, priority);
941}
942
943/**
944 * inet_csk_clone_lock - clone an inet socket, and lock its clone
945 * @sk: the socket to clone
946 * @req: request_sock
947 * @priority: for allocation (%GFP_KERNEL, %GFP_ATOMIC, etc)
948 *
949 * Caller must unlock socket even in error path (bh_unlock_sock(newsk))
950 */
951struct sock *inet_csk_clone_lock(const struct sock *sk,
952 const struct request_sock *req,
953 const gfp_t priority)
954{
955 struct sock *newsk = sk_clone_lock(sk, priority);
956
957 if (newsk) {
958 struct inet_connection_sock *newicsk = inet_csk(newsk);
959
960 inet_sk_set_state(newsk, TCP_SYN_RECV);
961 newicsk->icsk_bind_hash = NULL;
962
963 inet_sk(newsk)->inet_dport = inet_rsk(req)->ir_rmt_port;
964 inet_sk(newsk)->inet_num = inet_rsk(req)->ir_num;
965 inet_sk(newsk)->inet_sport = htons(inet_rsk(req)->ir_num);
966
967 /* listeners have SOCK_RCU_FREE, not the children */
968 sock_reset_flag(newsk, SOCK_RCU_FREE);
969
970 inet_sk(newsk)->mc_list = NULL;
971
972 newsk->sk_mark = inet_rsk(req)->ir_mark;
973 atomic64_set(&newsk->sk_cookie,
974 atomic64_read(&inet_rsk(req)->ir_cookie));
975
976 newicsk->icsk_retransmits = 0;
977 newicsk->icsk_backoff = 0;
978 newicsk->icsk_probes_out = 0;
979 newicsk->icsk_probes_tstamp = 0;
980
981 /* Deinitialize accept_queue to trap illegal accesses. */
982 memset(&newicsk->icsk_accept_queue, 0, sizeof(newicsk->icsk_accept_queue));
983
984 inet_clone_ulp(req, newsk, priority);
985
986 security_inet_csk_clone(newsk, req);
987 }
988 return newsk;
989}
990EXPORT_SYMBOL_GPL(inet_csk_clone_lock);
991
992/*
993 * At this point, there should be no process reference to this
994 * socket, and thus no user references at all. Therefore we
995 * can assume the socket waitqueue is inactive and nobody will
996 * try to jump onto it.
997 */
998void inet_csk_destroy_sock(struct sock *sk)
999{
1000 WARN_ON(sk->sk_state != TCP_CLOSE);
1001 WARN_ON(!sock_flag(sk, SOCK_DEAD));
1002
1003 /* It cannot be in hash table! */
1004 WARN_ON(!sk_unhashed(sk));
1005
1006 /* If it has not 0 inet_sk(sk)->inet_num, it must be bound */
1007 WARN_ON(inet_sk(sk)->inet_num && !inet_csk(sk)->icsk_bind_hash);
1008
1009 sk->sk_prot->destroy(sk);
1010
1011 sk_stream_kill_queues(sk);
1012
1013 xfrm_sk_free_policy(sk);
1014
1015 sk_refcnt_debug_release(sk);
1016
1017 percpu_counter_dec(sk->sk_prot->orphan_count);
1018
1019 sock_put(sk);
1020}
1021EXPORT_SYMBOL(inet_csk_destroy_sock);
1022
1023/* This function allows to force a closure of a socket after the call to
1024 * tcp/dccp_create_openreq_child().
1025 */
1026void inet_csk_prepare_forced_close(struct sock *sk)
1027 __releases(&sk->sk_lock.slock)
1028{
1029 /* sk_clone_lock locked the socket and set refcnt to 2 */
1030 bh_unlock_sock(sk);
1031 sock_put(sk);
1032 inet_csk_prepare_for_destroy_sock(sk);
1033 inet_sk(sk)->inet_num = 0;
1034}
1035EXPORT_SYMBOL(inet_csk_prepare_forced_close);
1036
1037int inet_csk_listen_start(struct sock *sk, int backlog)
1038{
1039 struct inet_connection_sock *icsk = inet_csk(sk);
1040 struct inet_sock *inet = inet_sk(sk);
1041 int err = -EADDRINUSE;
1042
1043 reqsk_queue_alloc(&icsk->icsk_accept_queue);
1044
1045 sk->sk_ack_backlog = 0;
1046 inet_csk_delack_init(sk);
1047
1048 /* There is race window here: we announce ourselves listening,
1049 * but this transition is still not validated by get_port().
1050 * It is OK, because this socket enters to hash table only
1051 * after validation is complete.
1052 */
1053 inet_sk_state_store(sk, TCP_LISTEN);
1054 if (!sk->sk_prot->get_port(sk, inet->inet_num)) {
1055 inet->inet_sport = htons(inet->inet_num);
1056
1057 sk_dst_reset(sk);
1058 err = sk->sk_prot->hash(sk);
1059
1060 if (likely(!err))
1061 return 0;
1062 }
1063
1064 inet_sk_set_state(sk, TCP_CLOSE);
1065 return err;
1066}
1067EXPORT_SYMBOL_GPL(inet_csk_listen_start);
1068
1069static void inet_child_forget(struct sock *sk, struct request_sock *req,
1070 struct sock *child)
1071{
1072 sk->sk_prot->disconnect(child, O_NONBLOCK);
1073
1074 sock_orphan(child);
1075
1076 percpu_counter_inc(sk->sk_prot->orphan_count);
1077
1078 if (sk->sk_protocol == IPPROTO_TCP && tcp_rsk(req)->tfo_listener) {
1079 BUG_ON(rcu_access_pointer(tcp_sk(child)->fastopen_rsk) != req);
1080 BUG_ON(sk != req->rsk_listener);
1081
1082 /* Paranoid, to prevent race condition if
1083 * an inbound pkt destined for child is
1084 * blocked by sock lock in tcp_v4_rcv().
1085 * Also to satisfy an assertion in
1086 * tcp_v4_destroy_sock().
1087 */
1088 RCU_INIT_POINTER(tcp_sk(child)->fastopen_rsk, NULL);
1089 }
1090 inet_csk_destroy_sock(child);
1091}
1092
1093struct sock *inet_csk_reqsk_queue_add(struct sock *sk,
1094 struct request_sock *req,
1095 struct sock *child)
1096{
1097 struct request_sock_queue *queue = &inet_csk(sk)->icsk_accept_queue;
1098
1099 spin_lock(&queue->rskq_lock);
1100 if (unlikely(sk->sk_state != TCP_LISTEN)) {
1101 inet_child_forget(sk, req, child);
1102 child = NULL;
1103 } else {
1104 req->sk = child;
1105 req->dl_next = NULL;
1106 if (queue->rskq_accept_head == NULL)
1107 WRITE_ONCE(queue->rskq_accept_head, req);
1108 else
1109 queue->rskq_accept_tail->dl_next = req;
1110 queue->rskq_accept_tail = req;
1111 sk_acceptq_added(sk);
1112 }
1113 spin_unlock(&queue->rskq_lock);
1114 return child;
1115}
1116EXPORT_SYMBOL(inet_csk_reqsk_queue_add);
1117
1118struct sock *inet_csk_complete_hashdance(struct sock *sk, struct sock *child,
1119 struct request_sock *req, bool own_req)
1120{
1121 if (own_req) {
1122 inet_csk_reqsk_queue_drop(req->rsk_listener, req);
1123 reqsk_queue_removed(&inet_csk(req->rsk_listener)->icsk_accept_queue, req);
1124
1125 if (sk != req->rsk_listener) {
1126 /* another listening sk has been selected,
1127 * migrate the req to it.
1128 */
1129 struct request_sock *nreq;
1130
1131 /* hold a refcnt for the nreq->rsk_listener
1132 * which is assigned in inet_reqsk_clone()
1133 */
1134 sock_hold(sk);
1135 nreq = inet_reqsk_clone(req, sk);
1136 if (!nreq) {
1137 inet_child_forget(sk, req, child);
1138 goto child_put;
1139 }
1140
1141 refcount_set(&nreq->rsk_refcnt, 1);
1142 if (inet_csk_reqsk_queue_add(sk, nreq, child)) {
1143 __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMIGRATEREQSUCCESS);
1144 reqsk_migrate_reset(req);
1145 reqsk_put(req);
1146 return child;
1147 }
1148
1149 __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMIGRATEREQFAILURE);
1150 reqsk_migrate_reset(nreq);
1151 __reqsk_free(nreq);
1152 } else if (inet_csk_reqsk_queue_add(sk, req, child)) {
1153 return child;
1154 }
1155 }
1156 /* Too bad, another child took ownership of the request, undo. */
1157child_put:
1158 bh_unlock_sock(child);
1159 sock_put(child);
1160 return NULL;
1161}
1162EXPORT_SYMBOL(inet_csk_complete_hashdance);
1163
1164/*
1165 * This routine closes sockets which have been at least partially
1166 * opened, but not yet accepted.
1167 */
1168void inet_csk_listen_stop(struct sock *sk)
1169{
1170 struct inet_connection_sock *icsk = inet_csk(sk);
1171 struct request_sock_queue *queue = &icsk->icsk_accept_queue;
1172 struct request_sock *next, *req;
1173
1174 /* Following specs, it would be better either to send FIN
1175 * (and enter FIN-WAIT-1, it is normal close)
1176 * or to send active reset (abort).
1177 * Certainly, it is pretty dangerous while synflood, but it is
1178 * bad justification for our negligence 8)
1179 * To be honest, we are not able to make either
1180 * of the variants now. --ANK
1181 */
1182 while ((req = reqsk_queue_remove(queue, sk)) != NULL) {
1183 struct sock *child = req->sk, *nsk;
1184 struct request_sock *nreq;
1185
1186 local_bh_disable();
1187 bh_lock_sock(child);
1188 WARN_ON(sock_owned_by_user(child));
1189 sock_hold(child);
1190
1191 nsk = reuseport_migrate_sock(sk, child, NULL);
1192 if (nsk) {
1193 nreq = inet_reqsk_clone(req, nsk);
1194 if (nreq) {
1195 refcount_set(&nreq->rsk_refcnt, 1);
1196
1197 if (inet_csk_reqsk_queue_add(nsk, nreq, child)) {
1198 __NET_INC_STATS(sock_net(nsk),
1199 LINUX_MIB_TCPMIGRATEREQSUCCESS);
1200 reqsk_migrate_reset(req);
1201 } else {
1202 __NET_INC_STATS(sock_net(nsk),
1203 LINUX_MIB_TCPMIGRATEREQFAILURE);
1204 reqsk_migrate_reset(nreq);
1205 __reqsk_free(nreq);
1206 }
1207
1208 /* inet_csk_reqsk_queue_add() has already
1209 * called inet_child_forget() on failure case.
1210 */
1211 goto skip_child_forget;
1212 }
1213 }
1214
1215 inet_child_forget(sk, req, child);
1216skip_child_forget:
1217 reqsk_put(req);
1218 bh_unlock_sock(child);
1219 local_bh_enable();
1220 sock_put(child);
1221
1222 cond_resched();
1223 }
1224 if (queue->fastopenq.rskq_rst_head) {
1225 /* Free all the reqs queued in rskq_rst_head. */
1226 spin_lock_bh(&queue->fastopenq.lock);
1227 req = queue->fastopenq.rskq_rst_head;
1228 queue->fastopenq.rskq_rst_head = NULL;
1229 spin_unlock_bh(&queue->fastopenq.lock);
1230 while (req != NULL) {
1231 next = req->dl_next;
1232 reqsk_put(req);
1233 req = next;
1234 }
1235 }
1236 WARN_ON_ONCE(sk->sk_ack_backlog);
1237}
1238EXPORT_SYMBOL_GPL(inet_csk_listen_stop);
1239
1240void inet_csk_addr2sockaddr(struct sock *sk, struct sockaddr *uaddr)
1241{
1242 struct sockaddr_in *sin = (struct sockaddr_in *)uaddr;
1243 const struct inet_sock *inet = inet_sk(sk);
1244
1245 sin->sin_family = AF_INET;
1246 sin->sin_addr.s_addr = inet->inet_daddr;
1247 sin->sin_port = inet->inet_dport;
1248}
1249EXPORT_SYMBOL_GPL(inet_csk_addr2sockaddr);
1250
1251static struct dst_entry *inet_csk_rebuild_route(struct sock *sk, struct flowi *fl)
1252{
1253 const struct inet_sock *inet = inet_sk(sk);
1254 const struct ip_options_rcu *inet_opt;
1255 __be32 daddr = inet->inet_daddr;
1256 struct flowi4 *fl4;
1257 struct rtable *rt;
1258
1259 rcu_read_lock();
1260 inet_opt = rcu_dereference(inet->inet_opt);
1261 if (inet_opt && inet_opt->opt.srr)
1262 daddr = inet_opt->opt.faddr;
1263 fl4 = &fl->u.ip4;
1264 rt = ip_route_output_ports(sock_net(sk), fl4, sk, daddr,
1265 inet->inet_saddr, inet->inet_dport,
1266 inet->inet_sport, sk->sk_protocol,
1267 RT_CONN_FLAGS(sk), sk->sk_bound_dev_if);
1268 if (IS_ERR(rt))
1269 rt = NULL;
1270 if (rt)
1271 sk_setup_caps(sk, &rt->dst);
1272 rcu_read_unlock();
1273
1274 return &rt->dst;
1275}
1276
1277struct dst_entry *inet_csk_update_pmtu(struct sock *sk, u32 mtu)
1278{
1279 struct dst_entry *dst = __sk_dst_check(sk, 0);
1280 struct inet_sock *inet = inet_sk(sk);
1281
1282 if (!dst) {
1283 dst = inet_csk_rebuild_route(sk, &inet->cork.fl);
1284 if (!dst)
1285 goto out;
1286 }
1287 dst->ops->update_pmtu(dst, sk, NULL, mtu, true);
1288
1289 dst = __sk_dst_check(sk, 0);
1290 if (!dst)
1291 dst = inet_csk_rebuild_route(sk, &inet->cork.fl);
1292out:
1293 return dst;
1294}
1295EXPORT_SYMBOL_GPL(inet_csk_update_pmtu);