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