1 /*
2  * INET		An implementation of the TCP/IP protocol suite for the LINUX
3  *		operating system.  INET is implemented using the  BSD Socket
4  *		interface as the means of communication with the user level.
5  *
6  *		Support for INET connection oriented protocols.
7  *
8  * Authors:	See the TCP sources
9  *
10  *		This program is free software; you can redistribute it and/or
11  *		modify it under the terms of the GNU General Public License
12  *		as published by the Free Software Foundation; either version
13  *		2 of the License, or(at your option) any later version.
14  */
15 
16 #include <linux/module.h>
17 #include <linux/jhash.h>
18 
19 #include <net/inet_connection_sock.h>
20 #include <net/inet_hashtables.h>
21 #include <net/inet_timewait_sock.h>
22 #include <net/ip.h>
23 #include <net/route.h>
24 #include <net/tcp_states.h>
25 #include <net/xfrm.h>
26 #include <net/tcp.h>
27 #include <net/sock_reuseport.h>
28 #include <net/addrconf.h>
29 
30 #if IS_ENABLED(CONFIG_IPV6)
31 /* match_wildcard == true:  IPV6_ADDR_ANY equals to any IPv6 addresses if IPv6
32  *                          only, and any IPv4 addresses if not IPv6 only
33  * match_wildcard == false: addresses must be exactly the same, i.e.
34  *                          IPV6_ADDR_ANY only equals to IPV6_ADDR_ANY,
35  *                          and 0.0.0.0 equals to 0.0.0.0 only
36  */
37 static bool ipv6_rcv_saddr_equal(const struct in6_addr *sk1_rcv_saddr6,
38 				 const struct in6_addr *sk2_rcv_saddr6,
39 				 __be32 sk1_rcv_saddr, __be32 sk2_rcv_saddr,
40 				 bool sk1_ipv6only, bool sk2_ipv6only,
41 				 bool match_wildcard)
42 {
43 	int addr_type = ipv6_addr_type(sk1_rcv_saddr6);
44 	int addr_type2 = sk2_rcv_saddr6 ? ipv6_addr_type(sk2_rcv_saddr6) : IPV6_ADDR_MAPPED;
45 
46 	/* if both are mapped, treat as IPv4 */
47 	if (addr_type == IPV6_ADDR_MAPPED && addr_type2 == IPV6_ADDR_MAPPED) {
48 		if (!sk2_ipv6only) {
49 			if (sk1_rcv_saddr == sk2_rcv_saddr)
50 				return true;
51 			if (!sk1_rcv_saddr || !sk2_rcv_saddr)
52 				return match_wildcard;
53 		}
54 		return false;
55 	}
56 
57 	if (addr_type == IPV6_ADDR_ANY && addr_type2 == IPV6_ADDR_ANY)
58 		return true;
59 
60 	if (addr_type2 == IPV6_ADDR_ANY && match_wildcard &&
61 	    !(sk2_ipv6only && addr_type == IPV6_ADDR_MAPPED))
62 		return true;
63 
64 	if (addr_type == IPV6_ADDR_ANY && match_wildcard &&
65 	    !(sk1_ipv6only && addr_type2 == IPV6_ADDR_MAPPED))
66 		return true;
67 
68 	if (sk2_rcv_saddr6 &&
69 	    ipv6_addr_equal(sk1_rcv_saddr6, sk2_rcv_saddr6))
70 		return true;
71 
72 	return false;
73 }
74 #endif
75 
76 /* match_wildcard == true:  0.0.0.0 equals to any IPv4 addresses
77  * match_wildcard == false: addresses must be exactly the same, i.e.
78  *                          0.0.0.0 only equals to 0.0.0.0
79  */
80 static bool ipv4_rcv_saddr_equal(__be32 sk1_rcv_saddr, __be32 sk2_rcv_saddr,
81 				 bool sk2_ipv6only, bool match_wildcard)
82 {
83 	if (!sk2_ipv6only) {
84 		if (sk1_rcv_saddr == sk2_rcv_saddr)
85 			return true;
86 		if (!sk1_rcv_saddr || !sk2_rcv_saddr)
87 			return match_wildcard;
88 	}
89 	return false;
90 }
91 
92 bool inet_rcv_saddr_equal(const struct sock *sk, const struct sock *sk2,
93 			  bool match_wildcard)
94 {
95 #if IS_ENABLED(CONFIG_IPV6)
96 	if (sk->sk_family == AF_INET6)
97 		return ipv6_rcv_saddr_equal(&sk->sk_v6_rcv_saddr,
98 					    inet6_rcv_saddr(sk2),
99 					    sk->sk_rcv_saddr,
100 					    sk2->sk_rcv_saddr,
101 					    ipv6_only_sock(sk),
102 					    ipv6_only_sock(sk2),
103 					    match_wildcard);
104 #endif
105 	return ipv4_rcv_saddr_equal(sk->sk_rcv_saddr, sk2->sk_rcv_saddr,
106 				    ipv6_only_sock(sk2), match_wildcard);
107 }
108 EXPORT_SYMBOL(inet_rcv_saddr_equal);
109 
110 void inet_get_local_port_range(struct net *net, int *low, int *high)
111 {
112 	unsigned int seq;
113 
114 	do {
115 		seq = read_seqbegin(&net->ipv4.ip_local_ports.lock);
116 
117 		*low = net->ipv4.ip_local_ports.range[0];
118 		*high = net->ipv4.ip_local_ports.range[1];
119 	} while (read_seqretry(&net->ipv4.ip_local_ports.lock, seq));
120 }
121 EXPORT_SYMBOL(inet_get_local_port_range);
122 
123 static int inet_csk_bind_conflict(const struct sock *sk,
124 				  const struct inet_bind_bucket *tb,
125 				  bool relax, bool reuseport_ok)
126 {
127 	struct sock *sk2;
128 	bool reuse = sk->sk_reuse;
129 	bool reuseport = !!sk->sk_reuseport && reuseport_ok;
130 	kuid_t uid = sock_i_uid((struct sock *)sk);
131 
132 	/*
133 	 * Unlike other sk lookup places we do not check
134 	 * for sk_net here, since _all_ the socks listed
135 	 * in tb->owners list belong to the same net - the
136 	 * one this bucket belongs to.
137 	 */
138 
139 	sk_for_each_bound(sk2, &tb->owners) {
140 		if (sk != sk2 &&
141 		    (!sk->sk_bound_dev_if ||
142 		     !sk2->sk_bound_dev_if ||
143 		     sk->sk_bound_dev_if == sk2->sk_bound_dev_if)) {
144 			if ((!reuse || !sk2->sk_reuse ||
145 			    sk2->sk_state == TCP_LISTEN) &&
146 			    (!reuseport || !sk2->sk_reuseport ||
147 			     rcu_access_pointer(sk->sk_reuseport_cb) ||
148 			     (sk2->sk_state != TCP_TIME_WAIT &&
149 			     !uid_eq(uid, sock_i_uid(sk2))))) {
150 				if (inet_rcv_saddr_equal(sk, sk2, true))
151 					break;
152 			}
153 			if (!relax && reuse && sk2->sk_reuse &&
154 			    sk2->sk_state != TCP_LISTEN) {
155 				if (inet_rcv_saddr_equal(sk, sk2, true))
156 					break;
157 			}
158 		}
159 	}
160 	return sk2 != NULL;
161 }
162 
163 /*
164  * Find an open port number for the socket.  Returns with the
165  * inet_bind_hashbucket lock held.
166  */
167 static struct inet_bind_hashbucket *
168 inet_csk_find_open_port(struct sock *sk, struct inet_bind_bucket **tb_ret, int *port_ret)
169 {
170 	struct inet_hashinfo *hinfo = sk->sk_prot->h.hashinfo;
171 	int port = 0;
172 	struct inet_bind_hashbucket *head;
173 	struct net *net = sock_net(sk);
174 	int i, low, high, attempt_half;
175 	struct inet_bind_bucket *tb;
176 	u32 remaining, offset;
177 
178 	attempt_half = (sk->sk_reuse == SK_CAN_REUSE) ? 1 : 0;
179 other_half_scan:
180 	inet_get_local_port_range(net, &low, &high);
181 	high++; /* [32768, 60999] -> [32768, 61000[ */
182 	if (high - low < 4)
183 		attempt_half = 0;
184 	if (attempt_half) {
185 		int half = low + (((high - low) >> 2) << 1);
186 
187 		if (attempt_half == 1)
188 			high = half;
189 		else
190 			low = half;
191 	}
192 	remaining = high - low;
193 	if (likely(remaining > 1))
194 		remaining &= ~1U;
195 
196 	offset = prandom_u32() % remaining;
197 	/* __inet_hash_connect() favors ports having @low parity
198 	 * We do the opposite to not pollute connect() users.
199 	 */
200 	offset |= 1U;
201 
202 other_parity_scan:
203 	port = low + offset;
204 	for (i = 0; i < remaining; i += 2, port += 2) {
205 		if (unlikely(port >= high))
206 			port -= remaining;
207 		if (inet_is_local_reserved_port(net, port))
208 			continue;
209 		head = &hinfo->bhash[inet_bhashfn(net, port,
210 						  hinfo->bhash_size)];
211 		spin_lock_bh(&head->lock);
212 		inet_bind_bucket_for_each(tb, &head->chain)
213 			if (net_eq(ib_net(tb), net) && tb->port == port) {
214 				if (!inet_csk_bind_conflict(sk, tb, false, false))
215 					goto success;
216 				goto next_port;
217 			}
218 		tb = NULL;
219 		goto success;
220 next_port:
221 		spin_unlock_bh(&head->lock);
222 		cond_resched();
223 	}
224 
225 	offset--;
226 	if (!(offset & 1))
227 		goto other_parity_scan;
228 
229 	if (attempt_half == 1) {
230 		/* OK we now try the upper half of the range */
231 		attempt_half = 2;
232 		goto other_half_scan;
233 	}
234 	return NULL;
235 success:
236 	*port_ret = port;
237 	*tb_ret = tb;
238 	return head;
239 }
240 
241 static inline int sk_reuseport_match(struct inet_bind_bucket *tb,
242 				     struct sock *sk)
243 {
244 	kuid_t uid = sock_i_uid(sk);
245 
246 	if (tb->fastreuseport <= 0)
247 		return 0;
248 	if (!sk->sk_reuseport)
249 		return 0;
250 	if (rcu_access_pointer(sk->sk_reuseport_cb))
251 		return 0;
252 	if (!uid_eq(tb->fastuid, uid))
253 		return 0;
254 	/* We only need to check the rcv_saddr if this tb was once marked
255 	 * without fastreuseport and then was reset, as we can only know that
256 	 * the fast_*rcv_saddr doesn't have any conflicts with the socks on the
257 	 * owners list.
258 	 */
259 	if (tb->fastreuseport == FASTREUSEPORT_ANY)
260 		return 1;
261 #if IS_ENABLED(CONFIG_IPV6)
262 	if (tb->fast_sk_family == AF_INET6)
263 		return ipv6_rcv_saddr_equal(&tb->fast_v6_rcv_saddr,
264 					    inet6_rcv_saddr(sk),
265 					    tb->fast_rcv_saddr,
266 					    sk->sk_rcv_saddr,
267 					    tb->fast_ipv6_only,
268 					    ipv6_only_sock(sk), true);
269 #endif
270 	return ipv4_rcv_saddr_equal(tb->fast_rcv_saddr, sk->sk_rcv_saddr,
271 				    ipv6_only_sock(sk), true);
272 }
273 
274 /* Obtain a reference to a local port for the given sock,
275  * if snum is zero it means select any available local port.
276  * We try to allocate an odd port (and leave even ports for connect())
277  */
278 int inet_csk_get_port(struct sock *sk, unsigned short snum)
279 {
280 	bool reuse = sk->sk_reuse && sk->sk_state != TCP_LISTEN;
281 	struct inet_hashinfo *hinfo = sk->sk_prot->h.hashinfo;
282 	int ret = 1, port = snum;
283 	struct inet_bind_hashbucket *head;
284 	struct net *net = sock_net(sk);
285 	struct inet_bind_bucket *tb = NULL;
286 	kuid_t uid = sock_i_uid(sk);
287 
288 	if (!port) {
289 		head = inet_csk_find_open_port(sk, &tb, &port);
290 		if (!head)
291 			return ret;
292 		if (!tb)
293 			goto tb_not_found;
294 		goto success;
295 	}
296 	head = &hinfo->bhash[inet_bhashfn(net, port,
297 					  hinfo->bhash_size)];
298 	spin_lock_bh(&head->lock);
299 	inet_bind_bucket_for_each(tb, &head->chain)
300 		if (net_eq(ib_net(tb), net) && tb->port == port)
301 			goto tb_found;
302 tb_not_found:
303 	tb = inet_bind_bucket_create(hinfo->bind_bucket_cachep,
304 				     net, head, port);
305 	if (!tb)
306 		goto fail_unlock;
307 tb_found:
308 	if (!hlist_empty(&tb->owners)) {
309 		if (sk->sk_reuse == SK_FORCE_REUSE)
310 			goto success;
311 
312 		if ((tb->fastreuse > 0 && reuse) ||
313 		    sk_reuseport_match(tb, sk))
314 			goto success;
315 		if (inet_csk_bind_conflict(sk, tb, true, true))
316 			goto fail_unlock;
317 	}
318 success:
319 	if (hlist_empty(&tb->owners)) {
320 		tb->fastreuse = reuse;
321 		if (sk->sk_reuseport) {
322 			tb->fastreuseport = FASTREUSEPORT_ANY;
323 			tb->fastuid = uid;
324 			tb->fast_rcv_saddr = sk->sk_rcv_saddr;
325 			tb->fast_ipv6_only = ipv6_only_sock(sk);
326 			tb->fast_sk_family = sk->sk_family;
327 #if IS_ENABLED(CONFIG_IPV6)
328 			tb->fast_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
329 #endif
330 		} else {
331 			tb->fastreuseport = 0;
332 		}
333 	} else {
334 		if (!reuse)
335 			tb->fastreuse = 0;
336 		if (sk->sk_reuseport) {
337 			/* We didn't match or we don't have fastreuseport set on
338 			 * the tb, but we have sk_reuseport set on this socket
339 			 * and we know that there are no bind conflicts with
340 			 * this socket in this tb, so reset our tb's reuseport
341 			 * settings so that any subsequent sockets that match
342 			 * our current socket will be put on the fast path.
343 			 *
344 			 * If we reset we need to set FASTREUSEPORT_STRICT so we
345 			 * do extra checking for all subsequent sk_reuseport
346 			 * socks.
347 			 */
348 			if (!sk_reuseport_match(tb, sk)) {
349 				tb->fastreuseport = FASTREUSEPORT_STRICT;
350 				tb->fastuid = uid;
351 				tb->fast_rcv_saddr = sk->sk_rcv_saddr;
352 				tb->fast_ipv6_only = ipv6_only_sock(sk);
353 				tb->fast_sk_family = sk->sk_family;
354 #if IS_ENABLED(CONFIG_IPV6)
355 				tb->fast_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
356 #endif
357 			}
358 		} else {
359 			tb->fastreuseport = 0;
360 		}
361 	}
362 	if (!inet_csk(sk)->icsk_bind_hash)
363 		inet_bind_hash(sk, tb, port);
364 	WARN_ON(inet_csk(sk)->icsk_bind_hash != tb);
365 	ret = 0;
366 
367 fail_unlock:
368 	spin_unlock_bh(&head->lock);
369 	return ret;
370 }
371 EXPORT_SYMBOL_GPL(inet_csk_get_port);
372 
373 /*
374  * Wait for an incoming connection, avoid race conditions. This must be called
375  * with the socket locked.
376  */
377 static int inet_csk_wait_for_connect(struct sock *sk, long timeo)
378 {
379 	struct inet_connection_sock *icsk = inet_csk(sk);
380 	DEFINE_WAIT(wait);
381 	int err;
382 
383 	/*
384 	 * True wake-one mechanism for incoming connections: only
385 	 * one process gets woken up, not the 'whole herd'.
386 	 * Since we do not 'race & poll' for established sockets
387 	 * anymore, the common case will execute the loop only once.
388 	 *
389 	 * Subtle issue: "add_wait_queue_exclusive()" will be added
390 	 * after any current non-exclusive waiters, and we know that
391 	 * it will always _stay_ after any new non-exclusive waiters
392 	 * because all non-exclusive waiters are added at the
393 	 * beginning of the wait-queue. As such, it's ok to "drop"
394 	 * our exclusiveness temporarily when we get woken up without
395 	 * having to remove and re-insert us on the wait queue.
396 	 */
397 	for (;;) {
398 		prepare_to_wait_exclusive(sk_sleep(sk), &wait,
399 					  TASK_INTERRUPTIBLE);
400 		release_sock(sk);
401 		if (reqsk_queue_empty(&icsk->icsk_accept_queue))
402 			timeo = schedule_timeout(timeo);
403 		sched_annotate_sleep();
404 		lock_sock(sk);
405 		err = 0;
406 		if (!reqsk_queue_empty(&icsk->icsk_accept_queue))
407 			break;
408 		err = -EINVAL;
409 		if (sk->sk_state != TCP_LISTEN)
410 			break;
411 		err = sock_intr_errno(timeo);
412 		if (signal_pending(current))
413 			break;
414 		err = -EAGAIN;
415 		if (!timeo)
416 			break;
417 	}
418 	finish_wait(sk_sleep(sk), &wait);
419 	return err;
420 }
421 
422 /*
423  * This will accept the next outstanding connection.
424  */
425 struct sock *inet_csk_accept(struct sock *sk, int flags, int *err, bool kern)
426 {
427 	struct inet_connection_sock *icsk = inet_csk(sk);
428 	struct request_sock_queue *queue = &icsk->icsk_accept_queue;
429 	struct request_sock *req;
430 	struct sock *newsk;
431 	int error;
432 
433 	lock_sock(sk);
434 
435 	/* We need to make sure that this socket is listening,
436 	 * and that it has something pending.
437 	 */
438 	error = -EINVAL;
439 	if (sk->sk_state != TCP_LISTEN)
440 		goto out_err;
441 
442 	/* Find already established connection */
443 	if (reqsk_queue_empty(queue)) {
444 		long timeo = sock_rcvtimeo(sk, flags & O_NONBLOCK);
445 
446 		/* If this is a non blocking socket don't sleep */
447 		error = -EAGAIN;
448 		if (!timeo)
449 			goto out_err;
450 
451 		error = inet_csk_wait_for_connect(sk, timeo);
452 		if (error)
453 			goto out_err;
454 	}
455 	req = reqsk_queue_remove(queue, sk);
456 	newsk = req->sk;
457 
458 	if (sk->sk_protocol == IPPROTO_TCP &&
459 	    tcp_rsk(req)->tfo_listener) {
460 		spin_lock_bh(&queue->fastopenq.lock);
461 		if (tcp_rsk(req)->tfo_listener) {
462 			/* We are still waiting for the final ACK from 3WHS
463 			 * so can't free req now. Instead, we set req->sk to
464 			 * NULL to signify that the child socket is taken
465 			 * so reqsk_fastopen_remove() will free the req
466 			 * when 3WHS finishes (or is aborted).
467 			 */
468 			req->sk = NULL;
469 			req = NULL;
470 		}
471 		spin_unlock_bh(&queue->fastopenq.lock);
472 	}
473 out:
474 	release_sock(sk);
475 	if (req)
476 		reqsk_put(req);
477 	return newsk;
478 out_err:
479 	newsk = NULL;
480 	req = NULL;
481 	*err = error;
482 	goto out;
483 }
484 EXPORT_SYMBOL(inet_csk_accept);
485 
486 /*
487  * Using different timers for retransmit, delayed acks and probes
488  * We may wish use just one timer maintaining a list of expire jiffies
489  * to optimize.
490  */
491 void inet_csk_init_xmit_timers(struct sock *sk,
492 			       void (*retransmit_handler)(struct timer_list *t),
493 			       void (*delack_handler)(struct timer_list *t),
494 			       void (*keepalive_handler)(struct timer_list *t))
495 {
496 	struct inet_connection_sock *icsk = inet_csk(sk);
497 
498 	timer_setup(&icsk->icsk_retransmit_timer, retransmit_handler, 0);
499 	timer_setup(&icsk->icsk_delack_timer, delack_handler, 0);
500 	timer_setup(&sk->sk_timer, keepalive_handler, 0);
501 	icsk->icsk_pending = icsk->icsk_ack.pending = 0;
502 }
503 EXPORT_SYMBOL(inet_csk_init_xmit_timers);
504 
505 void inet_csk_clear_xmit_timers(struct sock *sk)
506 {
507 	struct inet_connection_sock *icsk = inet_csk(sk);
508 
509 	icsk->icsk_pending = icsk->icsk_ack.pending = icsk->icsk_ack.blocked = 0;
510 
511 	sk_stop_timer(sk, &icsk->icsk_retransmit_timer);
512 	sk_stop_timer(sk, &icsk->icsk_delack_timer);
513 	sk_stop_timer(sk, &sk->sk_timer);
514 }
515 EXPORT_SYMBOL(inet_csk_clear_xmit_timers);
516 
517 void inet_csk_delete_keepalive_timer(struct sock *sk)
518 {
519 	sk_stop_timer(sk, &sk->sk_timer);
520 }
521 EXPORT_SYMBOL(inet_csk_delete_keepalive_timer);
522 
523 void inet_csk_reset_keepalive_timer(struct sock *sk, unsigned long len)
524 {
525 	sk_reset_timer(sk, &sk->sk_timer, jiffies + len);
526 }
527 EXPORT_SYMBOL(inet_csk_reset_keepalive_timer);
528 
529 struct dst_entry *inet_csk_route_req(const struct sock *sk,
530 				     struct flowi4 *fl4,
531 				     const struct request_sock *req)
532 {
533 	const struct inet_request_sock *ireq = inet_rsk(req);
534 	struct net *net = read_pnet(&ireq->ireq_net);
535 	struct ip_options_rcu *opt;
536 	struct rtable *rt;
537 
538 	opt = ireq_opt_deref(ireq);
539 
540 	flowi4_init_output(fl4, ireq->ir_iif, ireq->ir_mark,
541 			   RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE,
542 			   sk->sk_protocol, inet_sk_flowi_flags(sk),
543 			   (opt && opt->opt.srr) ? opt->opt.faddr : ireq->ir_rmt_addr,
544 			   ireq->ir_loc_addr, ireq->ir_rmt_port,
545 			   htons(ireq->ir_num), sk->sk_uid);
546 	security_req_classify_flow(req, flowi4_to_flowi(fl4));
547 	rt = ip_route_output_flow(net, fl4, sk);
548 	if (IS_ERR(rt))
549 		goto no_route;
550 	if (opt && opt->opt.is_strictroute && rt->rt_uses_gateway)
551 		goto route_err;
552 	return &rt->dst;
553 
554 route_err:
555 	ip_rt_put(rt);
556 no_route:
557 	__IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
558 	return NULL;
559 }
560 EXPORT_SYMBOL_GPL(inet_csk_route_req);
561 
562 struct dst_entry *inet_csk_route_child_sock(const struct sock *sk,
563 					    struct sock *newsk,
564 					    const struct request_sock *req)
565 {
566 	const struct inet_request_sock *ireq = inet_rsk(req);
567 	struct net *net = read_pnet(&ireq->ireq_net);
568 	struct inet_sock *newinet = inet_sk(newsk);
569 	struct ip_options_rcu *opt;
570 	struct flowi4 *fl4;
571 	struct rtable *rt;
572 
573 	opt = rcu_dereference(ireq->ireq_opt);
574 	fl4 = &newinet->cork.fl.u.ip4;
575 
576 	flowi4_init_output(fl4, ireq->ir_iif, ireq->ir_mark,
577 			   RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE,
578 			   sk->sk_protocol, inet_sk_flowi_flags(sk),
579 			   (opt && opt->opt.srr) ? opt->opt.faddr : ireq->ir_rmt_addr,
580 			   ireq->ir_loc_addr, ireq->ir_rmt_port,
581 			   htons(ireq->ir_num), sk->sk_uid);
582 	security_req_classify_flow(req, flowi4_to_flowi(fl4));
583 	rt = ip_route_output_flow(net, fl4, sk);
584 	if (IS_ERR(rt))
585 		goto no_route;
586 	if (opt && opt->opt.is_strictroute && rt->rt_uses_gateway)
587 		goto route_err;
588 	return &rt->dst;
589 
590 route_err:
591 	ip_rt_put(rt);
592 no_route:
593 	__IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
594 	return NULL;
595 }
596 EXPORT_SYMBOL_GPL(inet_csk_route_child_sock);
597 
598 #if IS_ENABLED(CONFIG_IPV6)
599 #define AF_INET_FAMILY(fam) ((fam) == AF_INET)
600 #else
601 #define AF_INET_FAMILY(fam) true
602 #endif
603 
604 /* Decide when to expire the request and when to resend SYN-ACK */
605 static inline void syn_ack_recalc(struct request_sock *req, const int thresh,
606 				  const int max_retries,
607 				  const u8 rskq_defer_accept,
608 				  int *expire, int *resend)
609 {
610 	if (!rskq_defer_accept) {
611 		*expire = req->num_timeout >= thresh;
612 		*resend = 1;
613 		return;
614 	}
615 	*expire = req->num_timeout >= thresh &&
616 		  (!inet_rsk(req)->acked || req->num_timeout >= max_retries);
617 	/*
618 	 * Do not resend while waiting for data after ACK,
619 	 * start to resend on end of deferring period to give
620 	 * last chance for data or ACK to create established socket.
621 	 */
622 	*resend = !inet_rsk(req)->acked ||
623 		  req->num_timeout >= rskq_defer_accept - 1;
624 }
625 
626 int inet_rtx_syn_ack(const struct sock *parent, struct request_sock *req)
627 {
628 	int err = req->rsk_ops->rtx_syn_ack(parent, req);
629 
630 	if (!err)
631 		req->num_retrans++;
632 	return err;
633 }
634 EXPORT_SYMBOL(inet_rtx_syn_ack);
635 
636 /* return true if req was found in the ehash table */
637 static bool reqsk_queue_unlink(struct request_sock_queue *queue,
638 			       struct request_sock *req)
639 {
640 	struct inet_hashinfo *hashinfo = req_to_sk(req)->sk_prot->h.hashinfo;
641 	bool found = false;
642 
643 	if (sk_hashed(req_to_sk(req))) {
644 		spinlock_t *lock = inet_ehash_lockp(hashinfo, req->rsk_hash);
645 
646 		spin_lock(lock);
647 		found = __sk_nulls_del_node_init_rcu(req_to_sk(req));
648 		spin_unlock(lock);
649 	}
650 	if (timer_pending(&req->rsk_timer) && del_timer_sync(&req->rsk_timer))
651 		reqsk_put(req);
652 	return found;
653 }
654 
655 void inet_csk_reqsk_queue_drop(struct sock *sk, struct request_sock *req)
656 {
657 	if (reqsk_queue_unlink(&inet_csk(sk)->icsk_accept_queue, req)) {
658 		reqsk_queue_removed(&inet_csk(sk)->icsk_accept_queue, req);
659 		reqsk_put(req);
660 	}
661 }
662 EXPORT_SYMBOL(inet_csk_reqsk_queue_drop);
663 
664 void inet_csk_reqsk_queue_drop_and_put(struct sock *sk, struct request_sock *req)
665 {
666 	inet_csk_reqsk_queue_drop(sk, req);
667 	reqsk_put(req);
668 }
669 EXPORT_SYMBOL(inet_csk_reqsk_queue_drop_and_put);
670 
671 static void reqsk_timer_handler(struct timer_list *t)
672 {
673 	struct request_sock *req = from_timer(req, t, rsk_timer);
674 	struct sock *sk_listener = req->rsk_listener;
675 	struct net *net = sock_net(sk_listener);
676 	struct inet_connection_sock *icsk = inet_csk(sk_listener);
677 	struct request_sock_queue *queue = &icsk->icsk_accept_queue;
678 	int qlen, expire = 0, resend = 0;
679 	int max_retries, thresh;
680 	u8 defer_accept;
681 
682 	if (inet_sk_state_load(sk_listener) != TCP_LISTEN)
683 		goto drop;
684 
685 	max_retries = icsk->icsk_syn_retries ? : net->ipv4.sysctl_tcp_synack_retries;
686 	thresh = max_retries;
687 	/* Normally all the openreqs are young and become mature
688 	 * (i.e. converted to established socket) for first timeout.
689 	 * If synack was not acknowledged for 1 second, it means
690 	 * one of the following things: synack was lost, ack was lost,
691 	 * rtt is high or nobody planned to ack (i.e. synflood).
692 	 * When server is a bit loaded, queue is populated with old
693 	 * open requests, reducing effective size of queue.
694 	 * When server is well loaded, queue size reduces to zero
695 	 * after several minutes of work. It is not synflood,
696 	 * it is normal operation. The solution is pruning
697 	 * too old entries overriding normal timeout, when
698 	 * situation becomes dangerous.
699 	 *
700 	 * Essentially, we reserve half of room for young
701 	 * embrions; and abort old ones without pity, if old
702 	 * ones are about to clog our table.
703 	 */
704 	qlen = reqsk_queue_len(queue);
705 	if ((qlen << 1) > max(8U, sk_listener->sk_max_ack_backlog)) {
706 		int young = reqsk_queue_len_young(queue) << 1;
707 
708 		while (thresh > 2) {
709 			if (qlen < young)
710 				break;
711 			thresh--;
712 			young <<= 1;
713 		}
714 	}
715 	defer_accept = READ_ONCE(queue->rskq_defer_accept);
716 	if (defer_accept)
717 		max_retries = defer_accept;
718 	syn_ack_recalc(req, thresh, max_retries, defer_accept,
719 		       &expire, &resend);
720 	req->rsk_ops->syn_ack_timeout(req);
721 	if (!expire &&
722 	    (!resend ||
723 	     !inet_rtx_syn_ack(sk_listener, req) ||
724 	     inet_rsk(req)->acked)) {
725 		unsigned long timeo;
726 
727 		if (req->num_timeout++ == 0)
728 			atomic_dec(&queue->young);
729 		timeo = min(TCP_TIMEOUT_INIT << req->num_timeout, TCP_RTO_MAX);
730 		mod_timer(&req->rsk_timer, jiffies + timeo);
731 		return;
732 	}
733 drop:
734 	inet_csk_reqsk_queue_drop_and_put(sk_listener, req);
735 }
736 
737 static void reqsk_queue_hash_req(struct request_sock *req,
738 				 unsigned long timeout)
739 {
740 	req->num_retrans = 0;
741 	req->num_timeout = 0;
742 	req->sk = NULL;
743 
744 	timer_setup(&req->rsk_timer, reqsk_timer_handler, TIMER_PINNED);
745 	mod_timer(&req->rsk_timer, jiffies + timeout);
746 
747 	inet_ehash_insert(req_to_sk(req), NULL);
748 	/* before letting lookups find us, make sure all req fields
749 	 * are committed to memory and refcnt initialized.
750 	 */
751 	smp_wmb();
752 	refcount_set(&req->rsk_refcnt, 2 + 1);
753 }
754 
755 void inet_csk_reqsk_queue_hash_add(struct sock *sk, struct request_sock *req,
756 				   unsigned long timeout)
757 {
758 	reqsk_queue_hash_req(req, timeout);
759 	inet_csk_reqsk_queue_added(sk);
760 }
761 EXPORT_SYMBOL_GPL(inet_csk_reqsk_queue_hash_add);
762 
763 /**
764  *	inet_csk_clone_lock - clone an inet socket, and lock its clone
765  *	@sk: the socket to clone
766  *	@req: request_sock
767  *	@priority: for allocation (%GFP_KERNEL, %GFP_ATOMIC, etc)
768  *
769  *	Caller must unlock socket even in error path (bh_unlock_sock(newsk))
770  */
771 struct sock *inet_csk_clone_lock(const struct sock *sk,
772 				 const struct request_sock *req,
773 				 const gfp_t priority)
774 {
775 	struct sock *newsk = sk_clone_lock(sk, priority);
776 
777 	if (newsk) {
778 		struct inet_connection_sock *newicsk = inet_csk(newsk);
779 
780 		inet_sk_set_state(newsk, TCP_SYN_RECV);
781 		newicsk->icsk_bind_hash = NULL;
782 
783 		inet_sk(newsk)->inet_dport = inet_rsk(req)->ir_rmt_port;
784 		inet_sk(newsk)->inet_num = inet_rsk(req)->ir_num;
785 		inet_sk(newsk)->inet_sport = htons(inet_rsk(req)->ir_num);
786 
787 		/* listeners have SOCK_RCU_FREE, not the children */
788 		sock_reset_flag(newsk, SOCK_RCU_FREE);
789 
790 		inet_sk(newsk)->mc_list = NULL;
791 
792 		newsk->sk_mark = inet_rsk(req)->ir_mark;
793 		atomic64_set(&newsk->sk_cookie,
794 			     atomic64_read(&inet_rsk(req)->ir_cookie));
795 
796 		newicsk->icsk_retransmits = 0;
797 		newicsk->icsk_backoff	  = 0;
798 		newicsk->icsk_probes_out  = 0;
799 
800 		/* Deinitialize accept_queue to trap illegal accesses. */
801 		memset(&newicsk->icsk_accept_queue, 0, sizeof(newicsk->icsk_accept_queue));
802 
803 		security_inet_csk_clone(newsk, req);
804 	}
805 	return newsk;
806 }
807 EXPORT_SYMBOL_GPL(inet_csk_clone_lock);
808 
809 /*
810  * At this point, there should be no process reference to this
811  * socket, and thus no user references at all.  Therefore we
812  * can assume the socket waitqueue is inactive and nobody will
813  * try to jump onto it.
814  */
815 void inet_csk_destroy_sock(struct sock *sk)
816 {
817 	WARN_ON(sk->sk_state != TCP_CLOSE);
818 	WARN_ON(!sock_flag(sk, SOCK_DEAD));
819 
820 	/* It cannot be in hash table! */
821 	WARN_ON(!sk_unhashed(sk));
822 
823 	/* If it has not 0 inet_sk(sk)->inet_num, it must be bound */
824 	WARN_ON(inet_sk(sk)->inet_num && !inet_csk(sk)->icsk_bind_hash);
825 
826 	sk->sk_prot->destroy(sk);
827 
828 	sk_stream_kill_queues(sk);
829 
830 	xfrm_sk_free_policy(sk);
831 
832 	sk_refcnt_debug_release(sk);
833 
834 	percpu_counter_dec(sk->sk_prot->orphan_count);
835 
836 	sock_put(sk);
837 }
838 EXPORT_SYMBOL(inet_csk_destroy_sock);
839 
840 /* This function allows to force a closure of a socket after the call to
841  * tcp/dccp_create_openreq_child().
842  */
843 void inet_csk_prepare_forced_close(struct sock *sk)
844 	__releases(&sk->sk_lock.slock)
845 {
846 	/* sk_clone_lock locked the socket and set refcnt to 2 */
847 	bh_unlock_sock(sk);
848 	sock_put(sk);
849 
850 	/* The below has to be done to allow calling inet_csk_destroy_sock */
851 	sock_set_flag(sk, SOCK_DEAD);
852 	percpu_counter_inc(sk->sk_prot->orphan_count);
853 	inet_sk(sk)->inet_num = 0;
854 }
855 EXPORT_SYMBOL(inet_csk_prepare_forced_close);
856 
857 int inet_csk_listen_start(struct sock *sk, int backlog)
858 {
859 	struct inet_connection_sock *icsk = inet_csk(sk);
860 	struct inet_sock *inet = inet_sk(sk);
861 	int err = -EADDRINUSE;
862 
863 	reqsk_queue_alloc(&icsk->icsk_accept_queue);
864 
865 	sk->sk_max_ack_backlog = backlog;
866 	sk->sk_ack_backlog = 0;
867 	inet_csk_delack_init(sk);
868 
869 	/* There is race window here: we announce ourselves listening,
870 	 * but this transition is still not validated by get_port().
871 	 * It is OK, because this socket enters to hash table only
872 	 * after validation is complete.
873 	 */
874 	inet_sk_state_store(sk, TCP_LISTEN);
875 	if (!sk->sk_prot->get_port(sk, inet->inet_num)) {
876 		inet->inet_sport = htons(inet->inet_num);
877 
878 		sk_dst_reset(sk);
879 		err = sk->sk_prot->hash(sk);
880 
881 		if (likely(!err))
882 			return 0;
883 	}
884 
885 	inet_sk_set_state(sk, TCP_CLOSE);
886 	return err;
887 }
888 EXPORT_SYMBOL_GPL(inet_csk_listen_start);
889 
890 static void inet_child_forget(struct sock *sk, struct request_sock *req,
891 			      struct sock *child)
892 {
893 	sk->sk_prot->disconnect(child, O_NONBLOCK);
894 
895 	sock_orphan(child);
896 
897 	percpu_counter_inc(sk->sk_prot->orphan_count);
898 
899 	if (sk->sk_protocol == IPPROTO_TCP && tcp_rsk(req)->tfo_listener) {
900 		BUG_ON(tcp_sk(child)->fastopen_rsk != req);
901 		BUG_ON(sk != req->rsk_listener);
902 
903 		/* Paranoid, to prevent race condition if
904 		 * an inbound pkt destined for child is
905 		 * blocked by sock lock in tcp_v4_rcv().
906 		 * Also to satisfy an assertion in
907 		 * tcp_v4_destroy_sock().
908 		 */
909 		tcp_sk(child)->fastopen_rsk = NULL;
910 	}
911 	inet_csk_destroy_sock(child);
912 }
913 
914 struct sock *inet_csk_reqsk_queue_add(struct sock *sk,
915 				      struct request_sock *req,
916 				      struct sock *child)
917 {
918 	struct request_sock_queue *queue = &inet_csk(sk)->icsk_accept_queue;
919 
920 	spin_lock(&queue->rskq_lock);
921 	if (unlikely(sk->sk_state != TCP_LISTEN)) {
922 		inet_child_forget(sk, req, child);
923 		child = NULL;
924 	} else {
925 		req->sk = child;
926 		req->dl_next = NULL;
927 		if (queue->rskq_accept_head == NULL)
928 			queue->rskq_accept_head = req;
929 		else
930 			queue->rskq_accept_tail->dl_next = req;
931 		queue->rskq_accept_tail = req;
932 		sk_acceptq_added(sk);
933 	}
934 	spin_unlock(&queue->rskq_lock);
935 	return child;
936 }
937 EXPORT_SYMBOL(inet_csk_reqsk_queue_add);
938 
939 struct sock *inet_csk_complete_hashdance(struct sock *sk, struct sock *child,
940 					 struct request_sock *req, bool own_req)
941 {
942 	if (own_req) {
943 		inet_csk_reqsk_queue_drop(sk, req);
944 		reqsk_queue_removed(&inet_csk(sk)->icsk_accept_queue, req);
945 		if (inet_csk_reqsk_queue_add(sk, req, child))
946 			return child;
947 	}
948 	/* Too bad, another child took ownership of the request, undo. */
949 	bh_unlock_sock(child);
950 	sock_put(child);
951 	return NULL;
952 }
953 EXPORT_SYMBOL(inet_csk_complete_hashdance);
954 
955 /*
956  *	This routine closes sockets which have been at least partially
957  *	opened, but not yet accepted.
958  */
959 void inet_csk_listen_stop(struct sock *sk)
960 {
961 	struct inet_connection_sock *icsk = inet_csk(sk);
962 	struct request_sock_queue *queue = &icsk->icsk_accept_queue;
963 	struct request_sock *next, *req;
964 
965 	/* Following specs, it would be better either to send FIN
966 	 * (and enter FIN-WAIT-1, it is normal close)
967 	 * or to send active reset (abort).
968 	 * Certainly, it is pretty dangerous while synflood, but it is
969 	 * bad justification for our negligence 8)
970 	 * To be honest, we are not able to make either
971 	 * of the variants now.			--ANK
972 	 */
973 	while ((req = reqsk_queue_remove(queue, sk)) != NULL) {
974 		struct sock *child = req->sk;
975 
976 		local_bh_disable();
977 		bh_lock_sock(child);
978 		WARN_ON(sock_owned_by_user(child));
979 		sock_hold(child);
980 
981 		inet_child_forget(sk, req, child);
982 		reqsk_put(req);
983 		bh_unlock_sock(child);
984 		local_bh_enable();
985 		sock_put(child);
986 
987 		cond_resched();
988 	}
989 	if (queue->fastopenq.rskq_rst_head) {
990 		/* Free all the reqs queued in rskq_rst_head. */
991 		spin_lock_bh(&queue->fastopenq.lock);
992 		req = queue->fastopenq.rskq_rst_head;
993 		queue->fastopenq.rskq_rst_head = NULL;
994 		spin_unlock_bh(&queue->fastopenq.lock);
995 		while (req != NULL) {
996 			next = req->dl_next;
997 			reqsk_put(req);
998 			req = next;
999 		}
1000 	}
1001 	WARN_ON_ONCE(sk->sk_ack_backlog);
1002 }
1003 EXPORT_SYMBOL_GPL(inet_csk_listen_stop);
1004 
1005 void inet_csk_addr2sockaddr(struct sock *sk, struct sockaddr *uaddr)
1006 {
1007 	struct sockaddr_in *sin = (struct sockaddr_in *)uaddr;
1008 	const struct inet_sock *inet = inet_sk(sk);
1009 
1010 	sin->sin_family		= AF_INET;
1011 	sin->sin_addr.s_addr	= inet->inet_daddr;
1012 	sin->sin_port		= inet->inet_dport;
1013 }
1014 EXPORT_SYMBOL_GPL(inet_csk_addr2sockaddr);
1015 
1016 #ifdef CONFIG_COMPAT
1017 int inet_csk_compat_getsockopt(struct sock *sk, int level, int optname,
1018 			       char __user *optval, int __user *optlen)
1019 {
1020 	const struct inet_connection_sock *icsk = inet_csk(sk);
1021 
1022 	if (icsk->icsk_af_ops->compat_getsockopt)
1023 		return icsk->icsk_af_ops->compat_getsockopt(sk, level, optname,
1024 							    optval, optlen);
1025 	return icsk->icsk_af_ops->getsockopt(sk, level, optname,
1026 					     optval, optlen);
1027 }
1028 EXPORT_SYMBOL_GPL(inet_csk_compat_getsockopt);
1029 
1030 int inet_csk_compat_setsockopt(struct sock *sk, int level, int optname,
1031 			       char __user *optval, unsigned int optlen)
1032 {
1033 	const struct inet_connection_sock *icsk = inet_csk(sk);
1034 
1035 	if (icsk->icsk_af_ops->compat_setsockopt)
1036 		return icsk->icsk_af_ops->compat_setsockopt(sk, level, optname,
1037 							    optval, optlen);
1038 	return icsk->icsk_af_ops->setsockopt(sk, level, optname,
1039 					     optval, optlen);
1040 }
1041 EXPORT_SYMBOL_GPL(inet_csk_compat_setsockopt);
1042 #endif
1043 
1044 static struct dst_entry *inet_csk_rebuild_route(struct sock *sk, struct flowi *fl)
1045 {
1046 	const struct inet_sock *inet = inet_sk(sk);
1047 	const struct ip_options_rcu *inet_opt;
1048 	__be32 daddr = inet->inet_daddr;
1049 	struct flowi4 *fl4;
1050 	struct rtable *rt;
1051 
1052 	rcu_read_lock();
1053 	inet_opt = rcu_dereference(inet->inet_opt);
1054 	if (inet_opt && inet_opt->opt.srr)
1055 		daddr = inet_opt->opt.faddr;
1056 	fl4 = &fl->u.ip4;
1057 	rt = ip_route_output_ports(sock_net(sk), fl4, sk, daddr,
1058 				   inet->inet_saddr, inet->inet_dport,
1059 				   inet->inet_sport, sk->sk_protocol,
1060 				   RT_CONN_FLAGS(sk), sk->sk_bound_dev_if);
1061 	if (IS_ERR(rt))
1062 		rt = NULL;
1063 	if (rt)
1064 		sk_setup_caps(sk, &rt->dst);
1065 	rcu_read_unlock();
1066 
1067 	return &rt->dst;
1068 }
1069 
1070 struct dst_entry *inet_csk_update_pmtu(struct sock *sk, u32 mtu)
1071 {
1072 	struct dst_entry *dst = __sk_dst_check(sk, 0);
1073 	struct inet_sock *inet = inet_sk(sk);
1074 
1075 	if (!dst) {
1076 		dst = inet_csk_rebuild_route(sk, &inet->cork.fl);
1077 		if (!dst)
1078 			goto out;
1079 	}
1080 	dst->ops->update_pmtu(dst, sk, NULL, mtu);
1081 
1082 	dst = __sk_dst_check(sk, 0);
1083 	if (!dst)
1084 		dst = inet_csk_rebuild_route(sk, &inet->cork.fl);
1085 out:
1086 	return dst;
1087 }
1088 EXPORT_SYMBOL_GPL(inet_csk_update_pmtu);
1089