1 // SPDX-License-Identifier: GPL-2.0-or-later
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.
7 * Support for INET connection oriented protocols.
9 * Authors: See the TCP sources
12 #include <linux/module.h>
13 #include <linux/jhash.h>
15 #include <net/inet_connection_sock.h>
16 #include <net/inet_hashtables.h>
17 #include <net/inet_timewait_sock.h>
19 #include <net/route.h>
20 #include <net/tcp_states.h>
23 #include <net/sock_reuseport.h>
24 #include <net/addrconf.h>
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
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
34 static 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)
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;
44 /* if both are mapped, treat as IPv4 */
45 if (addr_type == IPV6_ADDR_MAPPED && addr_type2 == IPV6_ADDR_MAPPED) {
47 if (sk1_rcv_saddr == sk2_rcv_saddr)
49 return (match_sk1_wildcard && !sk1_rcv_saddr) ||
50 (match_sk2_wildcard && !sk2_rcv_saddr);
55 if (addr_type == IPV6_ADDR_ANY && addr_type2 == IPV6_ADDR_ANY)
58 if (addr_type2 == IPV6_ADDR_ANY && match_sk2_wildcard &&
59 !(sk2_ipv6only && addr_type == IPV6_ADDR_MAPPED))
62 if (addr_type == IPV6_ADDR_ANY && match_sk1_wildcard &&
63 !(sk1_ipv6only && addr_type2 == IPV6_ADDR_MAPPED))
67 ipv6_addr_equal(sk1_rcv_saddr6, sk2_rcv_saddr6))
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
78 static 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)
83 if (sk1_rcv_saddr == sk2_rcv_saddr)
85 return (match_sk1_wildcard && !sk1_rcv_saddr) ||
86 (match_sk2_wildcard && !sk2_rcv_saddr);
91 bool inet_rcv_saddr_equal(const struct sock *sk, const struct sock *sk2,
94 #if IS_ENABLED(CONFIG_IPV6)
95 if (sk->sk_family == AF_INET6)
96 return ipv6_rcv_saddr_equal(&sk->sk_v6_rcv_saddr,
105 return ipv4_rcv_saddr_equal(sk->sk_rcv_saddr, sk2->sk_rcv_saddr,
106 ipv6_only_sock(sk2), match_wildcard,
109 EXPORT_SYMBOL(inet_rcv_saddr_equal);
111 bool inet_rcv_saddr_any(const struct sock *sk)
113 #if IS_ENABLED(CONFIG_IPV6)
114 if (sk->sk_family == AF_INET6)
115 return ipv6_addr_any(&sk->sk_v6_rcv_saddr);
117 return !sk->sk_rcv_saddr;
120 void inet_get_local_port_range(struct net *net, int *low, int *high)
125 seq = read_seqbegin(&net->ipv4.ip_local_ports.lock);
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));
131 EXPORT_SYMBOL(inet_get_local_port_range);
133 static int inet_csk_bind_conflict(const struct sock *sk,
134 const struct inet_bind_bucket *tb,
135 bool relax, bool reuseport_ok)
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);
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);
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.
157 sk_for_each_bound(sk2, &tb->owners) {
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) {
166 reuseport && sk2->sk_reuseport &&
168 (sk2->sk_state == TCP_TIME_WAIT ||
169 uid_eq(uid, sock_i_uid(sk2))))) &&
170 inet_rcv_saddr_equal(sk, sk2, true))
172 } else if (!reuseport_ok ||
173 !reuseport || !sk2->sk_reuseport ||
175 (sk2->sk_state != TCP_TIME_WAIT &&
176 !uid_eq(uid, sock_i_uid(sk2)))) {
177 if (inet_rcv_saddr_equal(sk, sk2, true))
186 * Find an open port number for the socket. Returns with the
187 * inet_bind_hashbucket lock held.
189 static struct inet_bind_hashbucket *
190 inet_csk_find_open_port(struct sock *sk, struct inet_bind_bucket **tb_ret, int *port_ret)
192 struct inet_hashinfo *hinfo = sk->sk_prot->h.hashinfo;
194 struct inet_bind_hashbucket *head;
195 struct net *net = sock_net(sk);
197 int i, low, high, attempt_half;
198 struct inet_bind_bucket *tb;
199 u32 remaining, offset;
202 l3mdev = inet_sk_bound_l3mdev(sk);
204 attempt_half = (sk->sk_reuse == SK_CAN_REUSE) ? 1 : 0;
206 inet_get_local_port_range(net, &low, &high);
207 high++; /* [32768, 60999] -> [32768, 61000[ */
211 int half = low + (((high - low) >> 2) << 1);
213 if (attempt_half == 1)
218 remaining = high - low;
219 if (likely(remaining > 1))
222 offset = prandom_u32() % remaining;
223 /* __inet_hash_connect() favors ports having @low parity
224 * We do the opposite to not pollute connect() users.
230 for (i = 0; i < remaining; i += 2, port += 2) {
231 if (unlikely(port >= high))
233 if (inet_is_local_reserved_port(net, port))
235 head = &hinfo->bhash[inet_bhashfn(net, port,
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 &&
241 if (!inet_csk_bind_conflict(sk, tb, relax, false))
248 spin_unlock_bh(&head->lock);
254 goto other_parity_scan;
256 if (attempt_half == 1) {
257 /* OK we now try the upper half of the range */
259 goto other_half_scan;
262 if (net->ipv4.sysctl_ip_autobind_reuse && !relax) {
263 /* We still have a chance to connect to different destinations */
265 goto ports_exhausted;
274 static inline int sk_reuseport_match(struct inet_bind_bucket *tb,
277 kuid_t uid = sock_i_uid(sk);
279 if (tb->fastreuseport <= 0)
281 if (!sk->sk_reuseport)
283 if (rcu_access_pointer(sk->sk_reuseport_cb))
285 if (!uid_eq(tb->fastuid, uid))
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
292 if (tb->fastreuseport == FASTREUSEPORT_ANY)
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,
301 ipv6_only_sock(sk), true, false);
303 return ipv4_rcv_saddr_equal(tb->fast_rcv_saddr, sk->sk_rcv_saddr,
304 ipv6_only_sock(sk), true, false);
307 void inet_csk_update_fastreuse(struct inet_bind_bucket *tb,
310 kuid_t uid = sock_i_uid(sk);
311 bool reuse = sk->sk_reuse && sk->sk_state != TCP_LISTEN;
313 if (hlist_empty(&tb->owners)) {
314 tb->fastreuse = reuse;
315 if (sk->sk_reuseport) {
316 tb->fastreuseport = FASTREUSEPORT_ANY;
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;
325 tb->fastreuseport = 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.
338 * If we reset we need to set FASTREUSEPORT_STRICT so we
339 * do extra checking for all subsequent sk_reuseport
342 if (!sk_reuseport_match(tb, sk)) {
343 tb->fastreuseport = FASTREUSEPORT_STRICT;
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;
353 tb->fastreuseport = 0;
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())
362 int inet_csk_get_port(struct sock *sk, unsigned short snum)
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;
372 l3mdev = inet_sk_bound_l3mdev(sk);
375 head = inet_csk_find_open_port(sk, &tb, &port);
382 head = &hinfo->bhash[inet_bhashfn(net, port,
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 &&
390 tb = inet_bind_bucket_create(hinfo->bind_bucket_cachep,
391 net, head, port, l3mdev);
395 if (!hlist_empty(&tb->owners)) {
396 if (sk->sk_reuse == SK_FORCE_REUSE)
399 if ((tb->fastreuse > 0 && reuse) ||
400 sk_reuseport_match(tb, sk))
402 if (inet_csk_bind_conflict(sk, tb, true, true))
406 inet_csk_update_fastreuse(tb, sk);
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);
414 spin_unlock_bh(&head->lock);
417 EXPORT_SYMBOL_GPL(inet_csk_get_port);
420 * Wait for an incoming connection, avoid race conditions. This must be called
421 * with the socket locked.
423 static int inet_csk_wait_for_connect(struct sock *sk, long timeo)
425 struct inet_connection_sock *icsk = inet_csk(sk);
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.
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.
444 prepare_to_wait_exclusive(sk_sleep(sk), &wait,
447 if (reqsk_queue_empty(&icsk->icsk_accept_queue))
448 timeo = schedule_timeout(timeo);
449 sched_annotate_sleep();
452 if (!reqsk_queue_empty(&icsk->icsk_accept_queue))
455 if (sk->sk_state != TCP_LISTEN)
457 err = sock_intr_errno(timeo);
458 if (signal_pending(current))
464 finish_wait(sk_sleep(sk), &wait);
469 * This will accept the next outstanding connection.
471 struct sock *inet_csk_accept(struct sock *sk, int flags, int *err, bool kern)
473 struct inet_connection_sock *icsk = inet_csk(sk);
474 struct request_sock_queue *queue = &icsk->icsk_accept_queue;
475 struct request_sock *req;
481 /* We need to make sure that this socket is listening,
482 * and that it has something pending.
485 if (sk->sk_state != TCP_LISTEN)
488 /* Find already established connection */
489 if (reqsk_queue_empty(queue)) {
490 long timeo = sock_rcvtimeo(sk, flags & O_NONBLOCK);
492 /* If this is a non blocking socket don't sleep */
497 error = inet_csk_wait_for_connect(sk, timeo);
501 req = reqsk_queue_remove(queue, sk);
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).
517 spin_unlock_bh(&queue->fastopenq.lock);
522 if (newsk && mem_cgroup_sockets_enabled) {
525 /* atomically get the memory usage, set and charge the
530 /* The socket has not been accepted yet, no need to look at
531 * newsk->sk_wmem_queued.
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);
550 EXPORT_SYMBOL(inet_csk_accept);
553 * Using different timers for retransmit, delayed acks and probes
554 * We may wish use just one timer maintaining a list of expire jiffies
557 void 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))
562 struct inet_connection_sock *icsk = inet_csk(sk);
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;
569 EXPORT_SYMBOL(inet_csk_init_xmit_timers);
571 void inet_csk_clear_xmit_timers(struct sock *sk)
573 struct inet_connection_sock *icsk = inet_csk(sk);
575 icsk->icsk_pending = icsk->icsk_ack.pending = 0;
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);
581 EXPORT_SYMBOL(inet_csk_clear_xmit_timers);
583 void inet_csk_delete_keepalive_timer(struct sock *sk)
585 sk_stop_timer(sk, &sk->sk_timer);
587 EXPORT_SYMBOL(inet_csk_delete_keepalive_timer);
589 void inet_csk_reset_keepalive_timer(struct sock *sk, unsigned long len)
591 sk_reset_timer(sk, &sk->sk_timer, jiffies + len);
593 EXPORT_SYMBOL(inet_csk_reset_keepalive_timer);
595 struct dst_entry *inet_csk_route_req(const struct sock *sk,
597 const struct request_sock *req)
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;
605 opt = rcu_dereference(ireq->ireq_opt);
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);
617 if (opt && opt->opt.is_strictroute && rt->rt_uses_gateway)
626 __IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
629 EXPORT_SYMBOL_GPL(inet_csk_route_req);
631 struct dst_entry *inet_csk_route_child_sock(const struct sock *sk,
633 const struct request_sock *req)
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;
642 opt = rcu_dereference(ireq->ireq_opt);
643 fl4 = &newinet->cork.fl.u.ip4;
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);
655 if (opt && opt->opt.is_strictroute && rt->rt_uses_gateway)
662 __IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
665 EXPORT_SYMBOL_GPL(inet_csk_route_child_sock);
667 /* Decide when to expire the request and when to resend SYN-ACK */
668 static 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)
673 if (!rskq_defer_accept) {
674 *expire = req->num_timeout >= max_syn_ack_retries;
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.
684 *resend = !inet_rsk(req)->acked ||
685 req->num_timeout >= rskq_defer_accept - 1;
688 int inet_rtx_syn_ack(const struct sock *parent, struct request_sock *req)
690 int err = req->rsk_ops->rtx_syn_ack(parent, req);
696 EXPORT_SYMBOL(inet_rtx_syn_ack);
698 static struct request_sock *inet_reqsk_clone(struct request_sock *req,
701 struct sock *req_sk, *nreq_sk;
702 struct request_sock *nreq;
704 nreq = kmem_cache_alloc(req->rsk_ops->slab, GFP_ATOMIC | __GFP_NOWARN);
706 __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMIGRATEREQFAILURE);
708 /* paired with refcount_inc_not_zero() in reuseport_migrate_sock() */
713 req_sk = req_to_sk(req);
714 nreq_sk = req_to_sk(nreq);
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));
721 sk_node_init(&nreq_sk->sk_node);
722 nreq_sk->sk_tx_queue_mapping = req_sk->sk_tx_queue_mapping;
724 nreq_sk->sk_rx_queue_mapping = req_sk->sk_rx_queue_mapping;
726 nreq_sk->sk_incoming_cpu = req_sk->sk_incoming_cpu;
728 nreq->rsk_listener = sk;
730 /* We need not acquire fastopenq->lock
731 * because the child socket is locked in inet_csk_listen_stop().
733 if (sk->sk_protocol == IPPROTO_TCP && tcp_rsk(nreq)->tfo_listener)
734 rcu_assign_pointer(tcp_sk(nreq->sk)->fastopen_rsk, nreq);
739 static void reqsk_queue_migrated(struct request_sock_queue *queue,
740 const struct request_sock *req)
742 if (req->num_timeout == 0)
743 atomic_inc(&queue->young);
744 atomic_inc(&queue->qlen);
747 static void reqsk_migrate_reset(struct request_sock *req)
749 req->saved_syn = NULL;
750 #if IS_ENABLED(CONFIG_IPV6)
751 inet_rsk(req)->ipv6_opt = NULL;
752 inet_rsk(req)->pktopts = NULL;
754 inet_rsk(req)->ireq_opt = NULL;
758 /* return true if req was found in the ehash table */
759 static bool reqsk_queue_unlink(struct request_sock *req)
761 struct inet_hashinfo *hashinfo = req_to_sk(req)->sk_prot->h.hashinfo;
764 if (sk_hashed(req_to_sk(req))) {
765 spinlock_t *lock = inet_ehash_lockp(hashinfo, req->rsk_hash);
768 found = __sk_nulls_del_node_init_rcu(req_to_sk(req));
771 if (timer_pending(&req->rsk_timer) && del_timer_sync(&req->rsk_timer))
776 bool inet_csk_reqsk_queue_drop(struct sock *sk, struct request_sock *req)
778 bool unlinked = reqsk_queue_unlink(req);
781 reqsk_queue_removed(&inet_csk(sk)->icsk_accept_queue, req);
786 EXPORT_SYMBOL(inet_csk_reqsk_queue_drop);
788 void inet_csk_reqsk_queue_drop_and_put(struct sock *sk, struct request_sock *req)
790 inet_csk_reqsk_queue_drop(sk, req);
793 EXPORT_SYMBOL(inet_csk_reqsk_queue_drop_and_put);
795 static void reqsk_timer_handler(struct timer_list *t)
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;
803 int max_syn_ack_retries, qlen, expire = 0, resend = 0;
805 if (inet_sk_state_load(sk_listener) != TCP_LISTEN) {
808 nsk = reuseport_migrate_sock(sk_listener, req_to_sk(req), NULL);
812 nreq = inet_reqsk_clone(req, nsk);
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.
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);
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.
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.
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;
854 while (max_syn_ack_retries > 2) {
857 max_syn_ack_retries--;
861 syn_ack_recalc(req, max_syn_ack_retries, READ_ONCE(queue->rskq_defer_accept),
863 req->rsk_ops->syn_ack_timeout(req);
866 !inet_rtx_syn_ack(sk_listener, req) ||
867 inet_rsk(req)->acked)) {
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);
878 if (!inet_ehash_insert(req_to_sk(nreq), req_to_sk(oreq), NULL)) {
880 inet_csk_reqsk_queue_drop(sk_listener, nreq);
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);
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.
898 __NET_INC_STATS(net, LINUX_MIB_TCPMIGRATEREQFAILURE);
900 reqsk_migrate_reset(nreq);
901 reqsk_queue_removed(queue, nreq);
906 inet_csk_reqsk_queue_drop_and_put(oreq->rsk_listener, oreq);
909 static void reqsk_queue_hash_req(struct request_sock *req,
910 unsigned long timeout)
912 timer_setup(&req->rsk_timer, reqsk_timer_handler, TIMER_PINNED);
913 mod_timer(&req->rsk_timer, jiffies + timeout);
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.
920 refcount_set(&req->rsk_refcnt, 2 + 1);
923 void inet_csk_reqsk_queue_hash_add(struct sock *sk, struct request_sock *req,
924 unsigned long timeout)
926 reqsk_queue_hash_req(req, timeout);
927 inet_csk_reqsk_queue_added(sk);
929 EXPORT_SYMBOL_GPL(inet_csk_reqsk_queue_hash_add);
931 static void inet_clone_ulp(const struct request_sock *req, struct sock *newsk,
932 const gfp_t priority)
934 struct inet_connection_sock *icsk = inet_csk(newsk);
936 if (!icsk->icsk_ulp_ops)
939 if (icsk->icsk_ulp_ops->clone)
940 icsk->icsk_ulp_ops->clone(req, newsk, priority);
944 * inet_csk_clone_lock - clone an inet socket, and lock its clone
945 * @sk: the socket to clone
947 * @priority: for allocation (%GFP_KERNEL, %GFP_ATOMIC, etc)
949 * Caller must unlock socket even in error path (bh_unlock_sock(newsk))
951 struct sock *inet_csk_clone_lock(const struct sock *sk,
952 const struct request_sock *req,
953 const gfp_t priority)
955 struct sock *newsk = sk_clone_lock(sk, priority);
958 struct inet_connection_sock *newicsk = inet_csk(newsk);
960 inet_sk_set_state(newsk, TCP_SYN_RECV);
961 newicsk->icsk_bind_hash = NULL;
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);
967 /* listeners have SOCK_RCU_FREE, not the children */
968 sock_reset_flag(newsk, SOCK_RCU_FREE);
970 inet_sk(newsk)->mc_list = NULL;
972 newsk->sk_mark = inet_rsk(req)->ir_mark;
973 atomic64_set(&newsk->sk_cookie,
974 atomic64_read(&inet_rsk(req)->ir_cookie));
976 newicsk->icsk_retransmits = 0;
977 newicsk->icsk_backoff = 0;
978 newicsk->icsk_probes_out = 0;
979 newicsk->icsk_probes_tstamp = 0;
981 /* Deinitialize accept_queue to trap illegal accesses. */
982 memset(&newicsk->icsk_accept_queue, 0, sizeof(newicsk->icsk_accept_queue));
984 inet_clone_ulp(req, newsk, priority);
986 security_inet_csk_clone(newsk, req);
990 EXPORT_SYMBOL_GPL(inet_csk_clone_lock);
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.
998 void inet_csk_destroy_sock(struct sock *sk)
1000 WARN_ON(sk->sk_state != TCP_CLOSE);
1001 WARN_ON(!sock_flag(sk, SOCK_DEAD));
1003 /* It cannot be in hash table! */
1004 WARN_ON(!sk_unhashed(sk));
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);
1009 sk->sk_prot->destroy(sk);
1011 sk_stream_kill_queues(sk);
1013 xfrm_sk_free_policy(sk);
1015 sk_refcnt_debug_release(sk);
1017 percpu_counter_dec(sk->sk_prot->orphan_count);
1021 EXPORT_SYMBOL(inet_csk_destroy_sock);
1023 /* This function allows to force a closure of a socket after the call to
1024 * tcp/dccp_create_openreq_child().
1026 void inet_csk_prepare_forced_close(struct sock *sk)
1027 __releases(&sk->sk_lock.slock)
1029 /* sk_clone_lock locked the socket and set refcnt to 2 */
1032 inet_csk_prepare_for_destroy_sock(sk);
1033 inet_sk(sk)->inet_num = 0;
1035 EXPORT_SYMBOL(inet_csk_prepare_forced_close);
1037 int inet_csk_listen_start(struct sock *sk, int backlog)
1039 struct inet_connection_sock *icsk = inet_csk(sk);
1040 struct inet_sock *inet = inet_sk(sk);
1041 int err = -EADDRINUSE;
1043 reqsk_queue_alloc(&icsk->icsk_accept_queue);
1045 sk->sk_ack_backlog = 0;
1046 inet_csk_delack_init(sk);
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.
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);
1058 err = sk->sk_prot->hash(sk);
1064 inet_sk_set_state(sk, TCP_CLOSE);
1067 EXPORT_SYMBOL_GPL(inet_csk_listen_start);
1069 static void inet_child_forget(struct sock *sk, struct request_sock *req,
1072 sk->sk_prot->disconnect(child, O_NONBLOCK);
1076 percpu_counter_inc(sk->sk_prot->orphan_count);
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);
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().
1088 RCU_INIT_POINTER(tcp_sk(child)->fastopen_rsk, NULL);
1090 inet_csk_destroy_sock(child);
1093 struct sock *inet_csk_reqsk_queue_add(struct sock *sk,
1094 struct request_sock *req,
1097 struct request_sock_queue *queue = &inet_csk(sk)->icsk_accept_queue;
1099 spin_lock(&queue->rskq_lock);
1100 if (unlikely(sk->sk_state != TCP_LISTEN)) {
1101 inet_child_forget(sk, req, child);
1105 req->dl_next = NULL;
1106 if (queue->rskq_accept_head == NULL)
1107 WRITE_ONCE(queue->rskq_accept_head, req);
1109 queue->rskq_accept_tail->dl_next = req;
1110 queue->rskq_accept_tail = req;
1111 sk_acceptq_added(sk);
1113 spin_unlock(&queue->rskq_lock);
1116 EXPORT_SYMBOL(inet_csk_reqsk_queue_add);
1118 struct sock *inet_csk_complete_hashdance(struct sock *sk, struct sock *child,
1119 struct request_sock *req, bool 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);
1125 if (sk != req->rsk_listener) {
1126 /* another listening sk has been selected,
1127 * migrate the req to it.
1129 struct request_sock *nreq;
1131 /* hold a refcnt for the nreq->rsk_listener
1132 * which is assigned in inet_reqsk_clone()
1135 nreq = inet_reqsk_clone(req, sk);
1137 inet_child_forget(sk, req, child);
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);
1149 __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMIGRATEREQFAILURE);
1150 reqsk_migrate_reset(nreq);
1152 } else if (inet_csk_reqsk_queue_add(sk, req, child)) {
1156 /* Too bad, another child took ownership of the request, undo. */
1158 bh_unlock_sock(child);
1162 EXPORT_SYMBOL(inet_csk_complete_hashdance);
1165 * This routine closes sockets which have been at least partially
1166 * opened, but not yet accepted.
1168 void inet_csk_listen_stop(struct sock *sk)
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;
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
1182 while ((req = reqsk_queue_remove(queue, sk)) != NULL) {
1183 struct sock *child = req->sk, *nsk;
1184 struct request_sock *nreq;
1187 bh_lock_sock(child);
1188 WARN_ON(sock_owned_by_user(child));
1191 nsk = reuseport_migrate_sock(sk, child, NULL);
1193 nreq = inet_reqsk_clone(req, nsk);
1195 refcount_set(&nreq->rsk_refcnt, 1);
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);
1202 __NET_INC_STATS(sock_net(nsk),
1203 LINUX_MIB_TCPMIGRATEREQFAILURE);
1204 reqsk_migrate_reset(nreq);
1208 /* inet_csk_reqsk_queue_add() has already
1209 * called inet_child_forget() on failure case.
1211 goto skip_child_forget;
1215 inet_child_forget(sk, req, child);
1218 bh_unlock_sock(child);
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;
1236 WARN_ON_ONCE(sk->sk_ack_backlog);
1238 EXPORT_SYMBOL_GPL(inet_csk_listen_stop);
1240 void inet_csk_addr2sockaddr(struct sock *sk, struct sockaddr *uaddr)
1242 struct sockaddr_in *sin = (struct sockaddr_in *)uaddr;
1243 const struct inet_sock *inet = inet_sk(sk);
1245 sin->sin_family = AF_INET;
1246 sin->sin_addr.s_addr = inet->inet_daddr;
1247 sin->sin_port = inet->inet_dport;
1249 EXPORT_SYMBOL_GPL(inet_csk_addr2sockaddr);
1251 static struct dst_entry *inet_csk_rebuild_route(struct sock *sk, struct flowi *fl)
1253 const struct inet_sock *inet = inet_sk(sk);
1254 const struct ip_options_rcu *inet_opt;
1255 __be32 daddr = inet->inet_daddr;
1260 inet_opt = rcu_dereference(inet->inet_opt);
1261 if (inet_opt && inet_opt->opt.srr)
1262 daddr = inet_opt->opt.faddr;
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);
1271 sk_setup_caps(sk, &rt->dst);
1277 struct dst_entry *inet_csk_update_pmtu(struct sock *sk, u32 mtu)
1279 struct dst_entry *dst = __sk_dst_check(sk, 0);
1280 struct inet_sock *inet = inet_sk(sk);
1283 dst = inet_csk_rebuild_route(sk, &inet->cork.fl);
1287 dst->ops->update_pmtu(dst, sk, NULL, mtu, true);
1289 dst = __sk_dst_check(sk, 0);
1291 dst = inet_csk_rebuild_route(sk, &inet->cork.fl);
1295 EXPORT_SYMBOL_GPL(inet_csk_update_pmtu);