1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3 * INET		An implementation of the TCP/IP protocol suite for the LINUX
   4 *		operating system.  INET is implemented using the  BSD Socket
   5 *		interface as the means of communication with the user level.
   6 *
   7 *		Support for INET connection oriented protocols.
   8 *
   9 * Authors:	See the TCP sources
  10 */
  11
  12#include <linux/module.h>
  13#include <linux/jhash.h>
  14
  15#include <net/inet_connection_sock.h>
  16#include <net/inet_hashtables.h>
  17#include <net/inet_timewait_sock.h>
  18#include <net/ip.h>
  19#include <net/route.h>
  20#include <net/tcp_states.h>
  21#include <net/xfrm.h>
  22#include <net/tcp.h>
  23#include <net/sock_reuseport.h>
  24#include <net/addrconf.h>
  25
  26#if IS_ENABLED(CONFIG_IPV6)
  27/* match_sk*_wildcard == true:  IPV6_ADDR_ANY equals to any IPv6 addresses
  28 *				if IPv6 only, and any IPv4 addresses
  29 *				if not IPv6 only
  30 * match_sk*_wildcard == false: addresses must be exactly the same, i.e.
  31 *				IPV6_ADDR_ANY only equals to IPV6_ADDR_ANY,
  32 *				and 0.0.0.0 equals to 0.0.0.0 only
  33 */
  34static bool ipv6_rcv_saddr_equal(const struct in6_addr *sk1_rcv_saddr6,
  35				 const struct in6_addr *sk2_rcv_saddr6,
  36				 __be32 sk1_rcv_saddr, __be32 sk2_rcv_saddr,
  37				 bool sk1_ipv6only, bool sk2_ipv6only,
  38				 bool match_sk1_wildcard,
  39				 bool match_sk2_wildcard)
  40{
  41	int addr_type = ipv6_addr_type(sk1_rcv_saddr6);
  42	int addr_type2 = sk2_rcv_saddr6 ? ipv6_addr_type(sk2_rcv_saddr6) : IPV6_ADDR_MAPPED;
  43
  44	/* if both are mapped, treat as IPv4 */
  45	if (addr_type == IPV6_ADDR_MAPPED && addr_type2 == IPV6_ADDR_MAPPED) {
  46		if (!sk2_ipv6only) {
  47			if (sk1_rcv_saddr == sk2_rcv_saddr)
  48				return true;
  49			return (match_sk1_wildcard && !sk1_rcv_saddr) ||
  50				(match_sk2_wildcard && !sk2_rcv_saddr);
  51		}
  52		return false;
  53	}
  54
  55	if (addr_type == IPV6_ADDR_ANY && addr_type2 == IPV6_ADDR_ANY)
  56		return true;
  57
  58	if (addr_type2 == IPV6_ADDR_ANY && match_sk2_wildcard &&
  59	    !(sk2_ipv6only && addr_type == IPV6_ADDR_MAPPED))
  60		return true;
  61
  62	if (addr_type == IPV6_ADDR_ANY && match_sk1_wildcard &&
  63	    !(sk1_ipv6only && addr_type2 == IPV6_ADDR_MAPPED))
  64		return true;
  65
  66	if (sk2_rcv_saddr6 &&
  67	    ipv6_addr_equal(sk1_rcv_saddr6, sk2_rcv_saddr6))
  68		return true;
  69
  70	return false;
  71}
  72#endif
  73
  74/* match_sk*_wildcard == true:  0.0.0.0 equals to any IPv4 addresses
  75 * match_sk*_wildcard == false: addresses must be exactly the same, i.e.
  76 *				0.0.0.0 only equals to 0.0.0.0
  77 */
  78static bool ipv4_rcv_saddr_equal(__be32 sk1_rcv_saddr, __be32 sk2_rcv_saddr,
  79				 bool sk2_ipv6only, bool match_sk1_wildcard,
  80				 bool match_sk2_wildcard)
  81{
  82	if (!sk2_ipv6only) {
  83		if (sk1_rcv_saddr == sk2_rcv_saddr)
  84			return true;
  85		return (match_sk1_wildcard && !sk1_rcv_saddr) ||
  86			(match_sk2_wildcard && !sk2_rcv_saddr);
  87	}
  88	return false;
  89}
  90
  91bool inet_rcv_saddr_equal(const struct sock *sk, const struct sock *sk2,
  92			  bool match_wildcard)
  93{
  94#if IS_ENABLED(CONFIG_IPV6)
  95	if (sk->sk_family == AF_INET6)
  96		return ipv6_rcv_saddr_equal(&sk->sk_v6_rcv_saddr,
  97					    inet6_rcv_saddr(sk2),
  98					    sk->sk_rcv_saddr,
  99					    sk2->sk_rcv_saddr,
 100					    ipv6_only_sock(sk),
 101					    ipv6_only_sock(sk2),
 102					    match_wildcard,
 103					    match_wildcard);
 104#endif
 105	return ipv4_rcv_saddr_equal(sk->sk_rcv_saddr, sk2->sk_rcv_saddr,
 106				    ipv6_only_sock(sk2), match_wildcard,
 107				    match_wildcard);
 108}
 109EXPORT_SYMBOL(inet_rcv_saddr_equal);
 110
 111bool inet_rcv_saddr_any(const struct sock *sk)
 112{
 113#if IS_ENABLED(CONFIG_IPV6)
 114	if (sk->sk_family == AF_INET6)
 115		return ipv6_addr_any(&sk->sk_v6_rcv_saddr);
 116#endif
 117	return !sk->sk_rcv_saddr;
 118}
 119
 120/**
 121 *	inet_sk_get_local_port_range - fetch ephemeral ports range
 122 *	@sk: socket
 123 *	@low: pointer to low port
 124 *	@high: pointer to high port
 125 *
 126 *	Fetch netns port range (/proc/sys/net/ipv4/ip_local_port_range)
 127 *	Range can be overridden if socket got IP_LOCAL_PORT_RANGE option.
 128 *	Returns true if IP_LOCAL_PORT_RANGE was set on this socket.
 129 */
 130bool inet_sk_get_local_port_range(const struct sock *sk, int *low, int *high)
 131{
 132	int lo, hi, sk_lo, sk_hi;
 133	bool local_range = false;
 134	u32 sk_range;
 135
 136	inet_get_local_port_range(sock_net(sk), &lo, &hi);
 137
 138	sk_range = READ_ONCE(inet_sk(sk)->local_port_range);
 139	if (unlikely(sk_range)) {
 140		sk_lo = sk_range & 0xffff;
 141		sk_hi = sk_range >> 16;
 142
 143		if (lo <= sk_lo && sk_lo <= hi)
 144			lo = sk_lo;
 145		if (lo <= sk_hi && sk_hi <= hi)
 146			hi = sk_hi;
 147		local_range = true;
 148	}
 149
 150	*low = lo;
 151	*high = hi;
 152	return local_range;
 153}
 154EXPORT_SYMBOL(inet_sk_get_local_port_range);
 155
 156static bool inet_use_bhash2_on_bind(const struct sock *sk)
 157{
 158#if IS_ENABLED(CONFIG_IPV6)
 159	if (sk->sk_family == AF_INET6) {
 160		int addr_type = ipv6_addr_type(&sk->sk_v6_rcv_saddr);
 161
 162		if (addr_type == IPV6_ADDR_ANY)
 163			return false;
 164
 165		if (addr_type != IPV6_ADDR_MAPPED)
 166			return true;
 167	}
 168#endif
 169	return sk->sk_rcv_saddr != htonl(INADDR_ANY);
 170}
 171
 172static bool inet_bind_conflict(const struct sock *sk, struct sock *sk2,
 173			       kuid_t sk_uid, bool relax,
 174			       bool reuseport_cb_ok, bool reuseport_ok)
 175{
 176	int bound_dev_if2;
 177
 178	if (sk == sk2)
 179		return false;
 180
 181	bound_dev_if2 = READ_ONCE(sk2->sk_bound_dev_if);
 182
 183	if (!sk->sk_bound_dev_if || !bound_dev_if2 ||
 184	    sk->sk_bound_dev_if == bound_dev_if2) {
 185		if (sk->sk_reuse && sk2->sk_reuse &&
 186		    sk2->sk_state != TCP_LISTEN) {
 187			if (!relax || (!reuseport_ok && sk->sk_reuseport &&
 188				       sk2->sk_reuseport && reuseport_cb_ok &&
 189				       (sk2->sk_state == TCP_TIME_WAIT ||
 190					uid_eq(sk_uid, sock_i_uid(sk2)))))
 191				return true;
 192		} else if (!reuseport_ok || !sk->sk_reuseport ||
 193			   !sk2->sk_reuseport || !reuseport_cb_ok ||
 194			   (sk2->sk_state != TCP_TIME_WAIT &&
 195			    !uid_eq(sk_uid, sock_i_uid(sk2)))) {
 196			return true;
 197		}
 198	}
 199	return false;
 200}
 201
 202static bool __inet_bhash2_conflict(const struct sock *sk, struct sock *sk2,
 203				   kuid_t sk_uid, bool relax,
 204				   bool reuseport_cb_ok, bool reuseport_ok)
 205{
 206	if (ipv6_only_sock(sk2)) {
 207		if (sk->sk_family == AF_INET)
 208			return false;
 209
 210#if IS_ENABLED(CONFIG_IPV6)
 211		if (ipv6_addr_v4mapped(&sk->sk_v6_rcv_saddr))
 212			return false;
 213#endif
 214	}
 215
 216	return inet_bind_conflict(sk, sk2, sk_uid, relax,
 217				  reuseport_cb_ok, reuseport_ok);
 218}
 219
 220static bool inet_bhash2_conflict(const struct sock *sk,
 221				 const struct inet_bind2_bucket *tb2,
 222				 kuid_t sk_uid,
 223				 bool relax, bool reuseport_cb_ok,
 224				 bool reuseport_ok)
 225{
 226	struct sock *sk2;
 227
 228	sk_for_each_bound(sk2, &tb2->owners) {
 229		if (__inet_bhash2_conflict(sk, sk2, sk_uid, relax,
 230					   reuseport_cb_ok, reuseport_ok))
 231			return true;
 232	}
 233
 234	return false;
 235}
 236
 237#define sk_for_each_bound_bhash(__sk, __tb2, __tb)			\
 238	hlist_for_each_entry(__tb2, &(__tb)->bhash2, bhash_node)	\
 239		sk_for_each_bound((__sk), &(__tb2)->owners)
 240
 241/* This should be called only when the tb and tb2 hashbuckets' locks are held */
 242static int inet_csk_bind_conflict(const struct sock *sk,
 243				  const struct inet_bind_bucket *tb,
 244				  const struct inet_bind2_bucket *tb2, /* may be null */
 245				  bool relax, bool reuseport_ok)
 246{
 247	kuid_t uid = sock_i_uid((struct sock *)sk);
 248	struct sock_reuseport *reuseport_cb;
 249	bool reuseport_cb_ok;
 250	struct sock *sk2;
 
 
 
 251
 252	rcu_read_lock();
 253	reuseport_cb = rcu_dereference(sk->sk_reuseport_cb);
 254	/* paired with WRITE_ONCE() in __reuseport_(add|detach)_closed_sock */
 255	reuseport_cb_ok = !reuseport_cb || READ_ONCE(reuseport_cb->num_closed_socks);
 256	rcu_read_unlock();
 257
 258	/* Conflicts with an existing IPV6_ADDR_ANY (if ipv6) or INADDR_ANY (if
 259	 * ipv4) should have been checked already. We need to do these two
 260	 * checks separately because their spinlocks have to be acquired/released
 261	 * independently of each other, to prevent possible deadlocks
 262	 */
 263	if (inet_use_bhash2_on_bind(sk))
 264		return tb2 && inet_bhash2_conflict(sk, tb2, uid, relax,
 265						   reuseport_cb_ok, reuseport_ok);
 266
 267	/* Unlike other sk lookup places we do not check
 268	 * for sk_net here, since _all_ the socks listed
 269	 * in tb->owners and tb2->owners list belong
 270	 * to the same net - the one this bucket belongs to.
 271	 */
 272	sk_for_each_bound_bhash(sk2, tb2, tb) {
 273		if (!inet_bind_conflict(sk, sk2, uid, relax, reuseport_cb_ok, reuseport_ok))
 274			continue;
 275
 276		if (inet_rcv_saddr_equal(sk, sk2, true))
 277			return true;
 278	}
 279
 280	return false;
 281}
 282
 283/* Determine if there is a bind conflict with an existing IPV6_ADDR_ANY (if ipv6) or
 284 * INADDR_ANY (if ipv4) socket.
 285 *
 286 * Caller must hold bhash hashbucket lock with local bh disabled, to protect
 287 * against concurrent binds on the port for addr any
 288 */
 289static bool inet_bhash2_addr_any_conflict(const struct sock *sk, int port, int l3mdev,
 290					  bool relax, bool reuseport_ok)
 291{
 292	kuid_t uid = sock_i_uid((struct sock *)sk);
 293	const struct net *net = sock_net(sk);
 294	struct sock_reuseport *reuseport_cb;
 295	struct inet_bind_hashbucket *head2;
 296	struct inet_bind2_bucket *tb2;
 297	bool conflict = false;
 298	bool reuseport_cb_ok;
 299
 300	rcu_read_lock();
 301	reuseport_cb = rcu_dereference(sk->sk_reuseport_cb);
 302	/* paired with WRITE_ONCE() in __reuseport_(add|detach)_closed_sock */
 303	reuseport_cb_ok = !reuseport_cb || READ_ONCE(reuseport_cb->num_closed_socks);
 304	rcu_read_unlock();
 305
 306	head2 = inet_bhash2_addr_any_hashbucket(sk, net, port);
 307
 308	spin_lock(&head2->lock);
 309
 310	inet_bind_bucket_for_each(tb2, &head2->chain) {
 311		if (!inet_bind2_bucket_match_addr_any(tb2, net, port, l3mdev, sk))
 312			continue;
 313
 314		if (!inet_bhash2_conflict(sk, tb2, uid, relax, reuseport_cb_ok,	reuseport_ok))
 315			continue;
 316
 317		conflict = true;
 318		break;
 
 
 
 
 
 
 
 
 
 
 
 
 
 319	}
 320
 321	spin_unlock(&head2->lock);
 322
 323	return conflict;
 324}
 325
 326/*
 327 * Find an open port number for the socket.  Returns with the
 328 * inet_bind_hashbucket locks held if successful.
 329 */
 330static struct inet_bind_hashbucket *
 331inet_csk_find_open_port(const struct sock *sk, struct inet_bind_bucket **tb_ret,
 332			struct inet_bind2_bucket **tb2_ret,
 333			struct inet_bind_hashbucket **head2_ret, int *port_ret)
 334{
 335	struct inet_hashinfo *hinfo = tcp_or_dccp_get_hashinfo(sk);
 336	int i, low, high, attempt_half, port, l3mdev;
 337	struct inet_bind_hashbucket *head, *head2;
 338	struct net *net = sock_net(sk);
 339	struct inet_bind2_bucket *tb2;
 
 340	struct inet_bind_bucket *tb;
 341	u32 remaining, offset;
 342	bool relax = false;
 343
 344	l3mdev = inet_sk_bound_l3mdev(sk);
 345ports_exhausted:
 346	attempt_half = (sk->sk_reuse == SK_CAN_REUSE) ? 1 : 0;
 347other_half_scan:
 348	inet_sk_get_local_port_range(sk, &low, &high);
 349	high++; /* [32768, 60999] -> [32768, 61000[ */
 350	if (high - low < 4)
 351		attempt_half = 0;
 352	if (attempt_half) {
 353		int half = low + (((high - low) >> 2) << 1);
 354
 355		if (attempt_half == 1)
 356			high = half;
 357		else
 358			low = half;
 359	}
 360	remaining = high - low;
 361	if (likely(remaining > 1))
 362		remaining &= ~1U;
 363
 364	offset = get_random_u32_below(remaining);
 365	/* __inet_hash_connect() favors ports having @low parity
 366	 * We do the opposite to not pollute connect() users.
 367	 */
 368	offset |= 1U;
 369
 370other_parity_scan:
 371	port = low + offset;
 372	for (i = 0; i < remaining; i += 2, port += 2) {
 373		if (unlikely(port >= high))
 374			port -= remaining;
 375		if (inet_is_local_reserved_port(net, port))
 376			continue;
 377		head = &hinfo->bhash[inet_bhashfn(net, port,
 378						  hinfo->bhash_size)];
 379		spin_lock_bh(&head->lock);
 380		if (inet_use_bhash2_on_bind(sk)) {
 381			if (inet_bhash2_addr_any_conflict(sk, port, l3mdev, relax, false))
 382				goto next_port;
 383		}
 384
 385		head2 = inet_bhashfn_portaddr(hinfo, sk, net, port);
 386		spin_lock(&head2->lock);
 387		tb2 = inet_bind2_bucket_find(head2, net, port, l3mdev, sk);
 388		inet_bind_bucket_for_each(tb, &head->chain)
 389			if (inet_bind_bucket_match(tb, net, port, l3mdev)) {
 390				if (!inet_csk_bind_conflict(sk, tb, tb2,
 391							    relax, false))
 392					goto success;
 393				spin_unlock(&head2->lock);
 394				goto next_port;
 395			}
 396		tb = NULL;
 397		goto success;
 398next_port:
 399		spin_unlock_bh(&head->lock);
 400		cond_resched();
 401	}
 402
 403	offset--;
 404	if (!(offset & 1))
 405		goto other_parity_scan;
 406
 407	if (attempt_half == 1) {
 408		/* OK we now try the upper half of the range */
 409		attempt_half = 2;
 410		goto other_half_scan;
 411	}
 412
 413	if (READ_ONCE(net->ipv4.sysctl_ip_autobind_reuse) && !relax) {
 414		/* We still have a chance to connect to different destinations */
 415		relax = true;
 416		goto ports_exhausted;
 417	}
 418	return NULL;
 419success:
 420	*port_ret = port;
 421	*tb_ret = tb;
 422	*tb2_ret = tb2;
 423	*head2_ret = head2;
 424	return head;
 425}
 426
 427static inline int sk_reuseport_match(struct inet_bind_bucket *tb,
 428				     struct sock *sk)
 429{
 430	kuid_t uid = sock_i_uid(sk);
 431
 432	if (tb->fastreuseport <= 0)
 433		return 0;
 434	if (!sk->sk_reuseport)
 435		return 0;
 436	if (rcu_access_pointer(sk->sk_reuseport_cb))
 437		return 0;
 438	if (!uid_eq(tb->fastuid, uid))
 439		return 0;
 440	/* We only need to check the rcv_saddr if this tb was once marked
 441	 * without fastreuseport and then was reset, as we can only know that
 442	 * the fast_*rcv_saddr doesn't have any conflicts with the socks on the
 443	 * owners list.
 444	 */
 445	if (tb->fastreuseport == FASTREUSEPORT_ANY)
 446		return 1;
 447#if IS_ENABLED(CONFIG_IPV6)
 448	if (tb->fast_sk_family == AF_INET6)
 449		return ipv6_rcv_saddr_equal(&tb->fast_v6_rcv_saddr,
 450					    inet6_rcv_saddr(sk),
 451					    tb->fast_rcv_saddr,
 452					    sk->sk_rcv_saddr,
 453					    tb->fast_ipv6_only,
 454					    ipv6_only_sock(sk), true, false);
 455#endif
 456	return ipv4_rcv_saddr_equal(tb->fast_rcv_saddr, sk->sk_rcv_saddr,
 457				    ipv6_only_sock(sk), true, false);
 458}
 459
 460void inet_csk_update_fastreuse(struct inet_bind_bucket *tb,
 461			       struct sock *sk)
 462{
 463	kuid_t uid = sock_i_uid(sk);
 464	bool reuse = sk->sk_reuse && sk->sk_state != TCP_LISTEN;
 465
 466	if (hlist_empty(&tb->bhash2)) {
 467		tb->fastreuse = reuse;
 468		if (sk->sk_reuseport) {
 469			tb->fastreuseport = FASTREUSEPORT_ANY;
 470			tb->fastuid = uid;
 471			tb->fast_rcv_saddr = sk->sk_rcv_saddr;
 472			tb->fast_ipv6_only = ipv6_only_sock(sk);
 473			tb->fast_sk_family = sk->sk_family;
 474#if IS_ENABLED(CONFIG_IPV6)
 475			tb->fast_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
 476#endif
 477		} else {
 478			tb->fastreuseport = 0;
 479		}
 480	} else {
 481		if (!reuse)
 482			tb->fastreuse = 0;
 483		if (sk->sk_reuseport) {
 484			/* We didn't match or we don't have fastreuseport set on
 485			 * the tb, but we have sk_reuseport set on this socket
 486			 * and we know that there are no bind conflicts with
 487			 * this socket in this tb, so reset our tb's reuseport
 488			 * settings so that any subsequent sockets that match
 489			 * our current socket will be put on the fast path.
 490			 *
 491			 * If we reset we need to set FASTREUSEPORT_STRICT so we
 492			 * do extra checking for all subsequent sk_reuseport
 493			 * socks.
 494			 */
 495			if (!sk_reuseport_match(tb, sk)) {
 496				tb->fastreuseport = FASTREUSEPORT_STRICT;
 497				tb->fastuid = uid;
 498				tb->fast_rcv_saddr = sk->sk_rcv_saddr;
 499				tb->fast_ipv6_only = ipv6_only_sock(sk);
 500				tb->fast_sk_family = sk->sk_family;
 501#if IS_ENABLED(CONFIG_IPV6)
 502				tb->fast_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
 503#endif
 504			}
 505		} else {
 506			tb->fastreuseport = 0;
 507		}
 508	}
 509}
 510
 511/* Obtain a reference to a local port for the given sock,
 512 * if snum is zero it means select any available local port.
 513 * We try to allocate an odd port (and leave even ports for connect())
 514 */
 515int inet_csk_get_port(struct sock *sk, unsigned short snum)
 516{
 517	struct inet_hashinfo *hinfo = tcp_or_dccp_get_hashinfo(sk);
 518	bool reuse = sk->sk_reuse && sk->sk_state != TCP_LISTEN;
 519	bool found_port = false, check_bind_conflict = true;
 520	bool bhash_created = false, bhash2_created = false;
 521	int ret = -EADDRINUSE, port = snum, l3mdev;
 522	struct inet_bind_hashbucket *head, *head2;
 523	struct inet_bind2_bucket *tb2 = NULL;
 524	struct inet_bind_bucket *tb = NULL;
 525	bool head2_lock_acquired = false;
 526	struct net *net = sock_net(sk);
 
 
 527
 528	l3mdev = inet_sk_bound_l3mdev(sk);
 529
 530	if (!port) {
 531		head = inet_csk_find_open_port(sk, &tb, &tb2, &head2, &port);
 532		if (!head)
 533			return ret;
 534
 535		head2_lock_acquired = true;
 536
 537		if (tb && tb2)
 538			goto success;
 539		found_port = true;
 540	} else {
 541		head = &hinfo->bhash[inet_bhashfn(net, port,
 542						  hinfo->bhash_size)];
 543		spin_lock_bh(&head->lock);
 544		inet_bind_bucket_for_each(tb, &head->chain)
 545			if (inet_bind_bucket_match(tb, net, port, l3mdev))
 546				break;
 547	}
 548
 549	if (!tb) {
 550		tb = inet_bind_bucket_create(hinfo->bind_bucket_cachep, net,
 551					     head, port, l3mdev);
 552		if (!tb)
 553			goto fail_unlock;
 554		bhash_created = true;
 555	}
 556
 557	if (!found_port) {
 558		if (!hlist_empty(&tb->bhash2)) {
 559			if (sk->sk_reuse == SK_FORCE_REUSE ||
 560			    (tb->fastreuse > 0 && reuse) ||
 561			    sk_reuseport_match(tb, sk))
 562				check_bind_conflict = false;
 563		}
 564
 565		if (check_bind_conflict && inet_use_bhash2_on_bind(sk)) {
 566			if (inet_bhash2_addr_any_conflict(sk, port, l3mdev, true, true))
 567				goto fail_unlock;
 568		}
 569
 570		head2 = inet_bhashfn_portaddr(hinfo, sk, net, port);
 571		spin_lock(&head2->lock);
 572		head2_lock_acquired = true;
 573		tb2 = inet_bind2_bucket_find(head2, net, port, l3mdev, sk);
 574	}
 575
 576	if (!tb2) {
 577		tb2 = inet_bind2_bucket_create(hinfo->bind2_bucket_cachep,
 578					       net, head2, tb, sk);
 579		if (!tb2)
 580			goto fail_unlock;
 581		bhash2_created = true;
 582	}
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 583
 584	if (!found_port && check_bind_conflict) {
 585		if (inet_csk_bind_conflict(sk, tb, tb2, true, true))
 
 
 586			goto fail_unlock;
 587	}
 588
 589success:
 590	inet_csk_update_fastreuse(tb, sk);
 591
 592	if (!inet_csk(sk)->icsk_bind_hash)
 593		inet_bind_hash(sk, tb, tb2, port);
 594	WARN_ON(inet_csk(sk)->icsk_bind_hash != tb);
 595	WARN_ON(inet_csk(sk)->icsk_bind2_hash != tb2);
 596	ret = 0;
 597
 598fail_unlock:
 599	if (ret) {
 600		if (bhash2_created)
 601			inet_bind2_bucket_destroy(hinfo->bind2_bucket_cachep, tb2);
 602		if (bhash_created)
 603			inet_bind_bucket_destroy(hinfo->bind_bucket_cachep, tb);
 604	}
 605	if (head2_lock_acquired)
 606		spin_unlock(&head2->lock);
 607	spin_unlock_bh(&head->lock);
 608	return ret;
 609}
 610EXPORT_SYMBOL_GPL(inet_csk_get_port);
 611
 612/*
 613 * Wait for an incoming connection, avoid race conditions. This must be called
 614 * with the socket locked.
 615 */
 616static int inet_csk_wait_for_connect(struct sock *sk, long timeo)
 617{
 618	struct inet_connection_sock *icsk = inet_csk(sk);
 619	DEFINE_WAIT(wait);
 620	int err;
 621
 622	/*
 623	 * True wake-one mechanism for incoming connections: only
 624	 * one process gets woken up, not the 'whole herd'.
 625	 * Since we do not 'race & poll' for established sockets
 626	 * anymore, the common case will execute the loop only once.
 627	 *
 628	 * Subtle issue: "add_wait_queue_exclusive()" will be added
 629	 * after any current non-exclusive waiters, and we know that
 630	 * it will always _stay_ after any new non-exclusive waiters
 631	 * because all non-exclusive waiters are added at the
 632	 * beginning of the wait-queue. As such, it's ok to "drop"
 633	 * our exclusiveness temporarily when we get woken up without
 634	 * having to remove and re-insert us on the wait queue.
 635	 */
 636	for (;;) {
 637		prepare_to_wait_exclusive(sk_sleep(sk), &wait,
 638					  TASK_INTERRUPTIBLE);
 639		release_sock(sk);
 640		if (reqsk_queue_empty(&icsk->icsk_accept_queue))
 641			timeo = schedule_timeout(timeo);
 642		sched_annotate_sleep();
 643		lock_sock(sk);
 644		err = 0;
 645		if (!reqsk_queue_empty(&icsk->icsk_accept_queue))
 646			break;
 647		err = -EINVAL;
 648		if (sk->sk_state != TCP_LISTEN)
 649			break;
 650		err = sock_intr_errno(timeo);
 651		if (signal_pending(current))
 652			break;
 653		err = -EAGAIN;
 654		if (!timeo)
 655			break;
 656	}
 657	finish_wait(sk_sleep(sk), &wait);
 658	return err;
 659}
 660
 661/*
 662 * This will accept the next outstanding connection.
 663 */
 664struct sock *inet_csk_accept(struct sock *sk, struct proto_accept_arg *arg)
 665{
 666	struct inet_connection_sock *icsk = inet_csk(sk);
 667	struct request_sock_queue *queue = &icsk->icsk_accept_queue;
 668	struct request_sock *req;
 669	struct sock *newsk;
 670	int error;
 671
 672	lock_sock(sk);
 673
 674	/* We need to make sure that this socket is listening,
 675	 * and that it has something pending.
 676	 */
 677	error = -EINVAL;
 678	if (sk->sk_state != TCP_LISTEN)
 679		goto out_err;
 680
 681	/* Find already established connection */
 682	if (reqsk_queue_empty(queue)) {
 683		long timeo = sock_rcvtimeo(sk, arg->flags & O_NONBLOCK);
 684
 685		/* If this is a non blocking socket don't sleep */
 686		error = -EAGAIN;
 687		if (!timeo)
 688			goto out_err;
 689
 690		error = inet_csk_wait_for_connect(sk, timeo);
 691		if (error)
 692			goto out_err;
 693	}
 694	req = reqsk_queue_remove(queue, sk);
 695	arg->is_empty = reqsk_queue_empty(queue);
 696	newsk = req->sk;
 697
 698	if (sk->sk_protocol == IPPROTO_TCP &&
 699	    tcp_rsk(req)->tfo_listener) {
 700		spin_lock_bh(&queue->fastopenq.lock);
 701		if (tcp_rsk(req)->tfo_listener) {
 702			/* We are still waiting for the final ACK from 3WHS
 703			 * so can't free req now. Instead, we set req->sk to
 704			 * NULL to signify that the child socket is taken
 705			 * so reqsk_fastopen_remove() will free the req
 706			 * when 3WHS finishes (or is aborted).
 707			 */
 708			req->sk = NULL;
 709			req = NULL;
 710		}
 711		spin_unlock_bh(&queue->fastopenq.lock);
 712	}
 713
 714out:
 715	release_sock(sk);
 716	if (newsk && mem_cgroup_sockets_enabled) {
 717		gfp_t gfp = GFP_KERNEL | __GFP_NOFAIL;
 718		int amt = 0;
 719
 720		/* atomically get the memory usage, set and charge the
 721		 * newsk->sk_memcg.
 722		 */
 723		lock_sock(newsk);
 724
 
 
 
 
 
 725		mem_cgroup_sk_alloc(newsk);
 726		if (newsk->sk_memcg) {
 727			/* The socket has not been accepted yet, no need
 728			 * to look at newsk->sk_wmem_queued.
 729			 */
 730			amt = sk_mem_pages(newsk->sk_forward_alloc +
 731					   atomic_read(&newsk->sk_rmem_alloc));
 732		}
 733
 734		if (amt)
 735			mem_cgroup_charge_skmem(newsk->sk_memcg, amt, gfp);
 736		kmem_cache_charge(newsk, gfp);
 737
 738		release_sock(newsk);
 739	}
 740	if (req)
 741		reqsk_put(req);
 742
 743	if (newsk)
 744		inet_init_csk_locks(newsk);
 745
 746	return newsk;
 747out_err:
 748	newsk = NULL;
 749	req = NULL;
 750	arg->err = error;
 751	goto out;
 752}
 753EXPORT_SYMBOL(inet_csk_accept);
 754
 755/*
 756 * Using different timers for retransmit, delayed acks and probes
 757 * We may wish use just one timer maintaining a list of expire jiffies
 758 * to optimize.
 759 */
 760void inet_csk_init_xmit_timers(struct sock *sk,
 761			       void (*retransmit_handler)(struct timer_list *t),
 762			       void (*delack_handler)(struct timer_list *t),
 763			       void (*keepalive_handler)(struct timer_list *t))
 764{
 765	struct inet_connection_sock *icsk = inet_csk(sk);
 766
 767	timer_setup(&icsk->icsk_retransmit_timer, retransmit_handler, 0);
 768	timer_setup(&icsk->icsk_delack_timer, delack_handler, 0);
 769	timer_setup(&sk->sk_timer, keepalive_handler, 0);
 770	icsk->icsk_pending = icsk->icsk_ack.pending = 0;
 771}
 772EXPORT_SYMBOL(inet_csk_init_xmit_timers);
 773
 774void inet_csk_clear_xmit_timers(struct sock *sk)
 775{
 776	struct inet_connection_sock *icsk = inet_csk(sk);
 777
 778	smp_store_release(&icsk->icsk_pending, 0);
 779	smp_store_release(&icsk->icsk_ack.pending, 0);
 780
 781	sk_stop_timer(sk, &icsk->icsk_retransmit_timer);
 782	sk_stop_timer(sk, &icsk->icsk_delack_timer);
 783	sk_stop_timer(sk, &sk->sk_timer);
 784}
 785EXPORT_SYMBOL(inet_csk_clear_xmit_timers);
 786
 787void inet_csk_clear_xmit_timers_sync(struct sock *sk)
 788{
 789	struct inet_connection_sock *icsk = inet_csk(sk);
 790
 791	/* ongoing timer handlers need to acquire socket lock. */
 792	sock_not_owned_by_me(sk);
 793
 794	smp_store_release(&icsk->icsk_pending, 0);
 795	smp_store_release(&icsk->icsk_ack.pending, 0);
 796
 797	sk_stop_timer_sync(sk, &icsk->icsk_retransmit_timer);
 798	sk_stop_timer_sync(sk, &icsk->icsk_delack_timer);
 799	sk_stop_timer_sync(sk, &sk->sk_timer);
 800}
 801
 802void inet_csk_delete_keepalive_timer(struct sock *sk)
 803{
 804	sk_stop_timer(sk, &sk->sk_timer);
 805}
 806EXPORT_SYMBOL(inet_csk_delete_keepalive_timer);
 807
 808void inet_csk_reset_keepalive_timer(struct sock *sk, unsigned long len)
 809{
 810	sk_reset_timer(sk, &sk->sk_timer, jiffies + len);
 811}
 812EXPORT_SYMBOL(inet_csk_reset_keepalive_timer);
 813
 814struct dst_entry *inet_csk_route_req(const struct sock *sk,
 815				     struct flowi4 *fl4,
 816				     const struct request_sock *req)
 817{
 818	const struct inet_request_sock *ireq = inet_rsk(req);
 819	struct net *net = read_pnet(&ireq->ireq_net);
 820	struct ip_options_rcu *opt;
 821	struct rtable *rt;
 822
 823	rcu_read_lock();
 824	opt = rcu_dereference(ireq->ireq_opt);
 825
 826	flowi4_init_output(fl4, ireq->ir_iif, ireq->ir_mark,
 827			   ip_sock_rt_tos(sk), ip_sock_rt_scope(sk),
 828			   sk->sk_protocol, inet_sk_flowi_flags(sk),
 829			   (opt && opt->opt.srr) ? opt->opt.faddr : ireq->ir_rmt_addr,
 830			   ireq->ir_loc_addr, ireq->ir_rmt_port,
 831			   htons(ireq->ir_num), sk->sk_uid);
 832	security_req_classify_flow(req, flowi4_to_flowi_common(fl4));
 833	rt = ip_route_output_flow(net, fl4, sk);
 834	if (IS_ERR(rt))
 835		goto no_route;
 836	if (opt && opt->opt.is_strictroute && rt->rt_uses_gateway)
 837		goto route_err;
 838	rcu_read_unlock();
 839	return &rt->dst;
 840
 841route_err:
 842	ip_rt_put(rt);
 843no_route:
 844	rcu_read_unlock();
 845	__IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
 846	return NULL;
 847}
 848EXPORT_SYMBOL_GPL(inet_csk_route_req);
 849
 850struct dst_entry *inet_csk_route_child_sock(const struct sock *sk,
 851					    struct sock *newsk,
 852					    const struct request_sock *req)
 853{
 854	const struct inet_request_sock *ireq = inet_rsk(req);
 855	struct net *net = read_pnet(&ireq->ireq_net);
 856	struct inet_sock *newinet = inet_sk(newsk);
 857	struct ip_options_rcu *opt;
 858	struct flowi4 *fl4;
 859	struct rtable *rt;
 860
 861	opt = rcu_dereference(ireq->ireq_opt);
 862	fl4 = &newinet->cork.fl.u.ip4;
 863
 864	flowi4_init_output(fl4, ireq->ir_iif, ireq->ir_mark,
 865			   ip_sock_rt_tos(sk), ip_sock_rt_scope(sk),
 866			   sk->sk_protocol, inet_sk_flowi_flags(sk),
 867			   (opt && opt->opt.srr) ? opt->opt.faddr : ireq->ir_rmt_addr,
 868			   ireq->ir_loc_addr, ireq->ir_rmt_port,
 869			   htons(ireq->ir_num), sk->sk_uid);
 870	security_req_classify_flow(req, flowi4_to_flowi_common(fl4));
 871	rt = ip_route_output_flow(net, fl4, sk);
 872	if (IS_ERR(rt))
 873		goto no_route;
 874	if (opt && opt->opt.is_strictroute && rt->rt_uses_gateway)
 875		goto route_err;
 876	return &rt->dst;
 877
 878route_err:
 879	ip_rt_put(rt);
 880no_route:
 881	__IP_INC_STATS(net, IPSTATS_MIB_OUTNOROUTES);
 882	return NULL;
 883}
 884EXPORT_SYMBOL_GPL(inet_csk_route_child_sock);
 885
 886/* Decide when to expire the request and when to resend SYN-ACK */
 887static void syn_ack_recalc(struct request_sock *req,
 888			   const int max_syn_ack_retries,
 889			   const u8 rskq_defer_accept,
 890			   int *expire, int *resend)
 891{
 892	if (!rskq_defer_accept) {
 893		*expire = req->num_timeout >= max_syn_ack_retries;
 894		*resend = 1;
 895		return;
 896	}
 897	*expire = req->num_timeout >= max_syn_ack_retries &&
 898		  (!inet_rsk(req)->acked || req->num_timeout >= rskq_defer_accept);
 899	/* Do not resend while waiting for data after ACK,
 900	 * start to resend on end of deferring period to give
 901	 * last chance for data or ACK to create established socket.
 902	 */
 903	*resend = !inet_rsk(req)->acked ||
 904		  req->num_timeout >= rskq_defer_accept - 1;
 905}
 906
 907int inet_rtx_syn_ack(const struct sock *parent, struct request_sock *req)
 908{
 909	int err = req->rsk_ops->rtx_syn_ack(parent, req);
 910
 911	if (!err)
 912		req->num_retrans++;
 913	return err;
 914}
 915EXPORT_SYMBOL(inet_rtx_syn_ack);
 916
 917static struct request_sock *
 918reqsk_alloc_noprof(const struct request_sock_ops *ops, struct sock *sk_listener,
 919		   bool attach_listener)
 920{
 921	struct request_sock *req;
 922
 923	req = kmem_cache_alloc_noprof(ops->slab, GFP_ATOMIC | __GFP_NOWARN);
 924	if (!req)
 925		return NULL;
 926	req->rsk_listener = NULL;
 927	if (attach_listener) {
 928		if (unlikely(!refcount_inc_not_zero(&sk_listener->sk_refcnt))) {
 929			kmem_cache_free(ops->slab, req);
 930			return NULL;
 931		}
 932		req->rsk_listener = sk_listener;
 933	}
 934	req->rsk_ops = ops;
 935	req_to_sk(req)->sk_prot = sk_listener->sk_prot;
 936	sk_node_init(&req_to_sk(req)->sk_node);
 937	sk_tx_queue_clear(req_to_sk(req));
 938	req->saved_syn = NULL;
 939	req->syncookie = 0;
 940	req->timeout = 0;
 941	req->num_timeout = 0;
 942	req->num_retrans = 0;
 943	req->sk = NULL;
 944	refcount_set(&req->rsk_refcnt, 0);
 945
 946	return req;
 947}
 948#define reqsk_alloc(...)	alloc_hooks(reqsk_alloc_noprof(__VA_ARGS__))
 949
 950struct request_sock *inet_reqsk_alloc(const struct request_sock_ops *ops,
 951				      struct sock *sk_listener,
 952				      bool attach_listener)
 953{
 954	struct request_sock *req = reqsk_alloc(ops, sk_listener,
 955					       attach_listener);
 956
 957	if (req) {
 958		struct inet_request_sock *ireq = inet_rsk(req);
 959
 960		ireq->ireq_opt = NULL;
 961#if IS_ENABLED(CONFIG_IPV6)
 962		ireq->pktopts = NULL;
 963#endif
 964		atomic64_set(&ireq->ir_cookie, 0);
 965		ireq->ireq_state = TCP_NEW_SYN_RECV;
 966		write_pnet(&ireq->ireq_net, sock_net(sk_listener));
 967		ireq->ireq_family = sk_listener->sk_family;
 968		req->timeout = TCP_TIMEOUT_INIT;
 969	}
 970
 971	return req;
 972}
 973EXPORT_SYMBOL(inet_reqsk_alloc);
 974
 975static struct request_sock *inet_reqsk_clone(struct request_sock *req,
 976					     struct sock *sk)
 977{
 978	struct sock *req_sk, *nreq_sk;
 979	struct request_sock *nreq;
 980
 981	nreq = kmem_cache_alloc(req->rsk_ops->slab, GFP_ATOMIC | __GFP_NOWARN);
 982	if (!nreq) {
 983		__NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMIGRATEREQFAILURE);
 984
 985		/* paired with refcount_inc_not_zero() in reuseport_migrate_sock() */
 986		sock_put(sk);
 987		return NULL;
 988	}
 989
 990	req_sk = req_to_sk(req);
 991	nreq_sk = req_to_sk(nreq);
 992
 993	memcpy(nreq_sk, req_sk,
 994	       offsetof(struct sock, sk_dontcopy_begin));
 995	unsafe_memcpy(&nreq_sk->sk_dontcopy_end, &req_sk->sk_dontcopy_end,
 996		      req->rsk_ops->obj_size - offsetof(struct sock, sk_dontcopy_end),
 997		      /* alloc is larger than struct, see above */);
 998
 999	sk_node_init(&nreq_sk->sk_node);
1000	nreq_sk->sk_tx_queue_mapping = req_sk->sk_tx_queue_mapping;
1001#ifdef CONFIG_SOCK_RX_QUEUE_MAPPING
1002	nreq_sk->sk_rx_queue_mapping = req_sk->sk_rx_queue_mapping;
1003#endif
1004	nreq_sk->sk_incoming_cpu = req_sk->sk_incoming_cpu;
1005
1006	nreq->rsk_listener = sk;
1007
1008	/* We need not acquire fastopenq->lock
1009	 * because the child socket is locked in inet_csk_listen_stop().
1010	 */
1011	if (sk->sk_protocol == IPPROTO_TCP && tcp_rsk(nreq)->tfo_listener)
1012		rcu_assign_pointer(tcp_sk(nreq->sk)->fastopen_rsk, nreq);
1013
1014	return nreq;
1015}
1016
1017static void reqsk_queue_migrated(struct request_sock_queue *queue,
1018				 const struct request_sock *req)
1019{
1020	if (req->num_timeout == 0)
1021		atomic_inc(&queue->young);
1022	atomic_inc(&queue->qlen);
1023}
1024
1025static void reqsk_migrate_reset(struct request_sock *req)
1026{
1027	req->saved_syn = NULL;
1028#if IS_ENABLED(CONFIG_IPV6)
1029	inet_rsk(req)->ipv6_opt = NULL;
1030	inet_rsk(req)->pktopts = NULL;
1031#else
1032	inet_rsk(req)->ireq_opt = NULL;
1033#endif
1034}
1035
1036/* return true if req was found in the ehash table */
1037static bool reqsk_queue_unlink(struct request_sock *req)
1038{
1039	struct sock *sk = req_to_sk(req);
1040	bool found = false;
1041
1042	if (sk_hashed(sk)) {
1043		struct inet_hashinfo *hashinfo = tcp_or_dccp_get_hashinfo(sk);
1044		spinlock_t *lock = inet_ehash_lockp(hashinfo, req->rsk_hash);
1045
1046		spin_lock(lock);
1047		found = __sk_nulls_del_node_init_rcu(sk);
1048		spin_unlock(lock);
1049	}
1050
 
1051	return found;
1052}
1053
1054static bool __inet_csk_reqsk_queue_drop(struct sock *sk,
1055					struct request_sock *req,
1056					bool from_timer)
1057{
1058	bool unlinked = reqsk_queue_unlink(req);
1059
1060	if (!from_timer && timer_delete_sync(&req->rsk_timer))
1061		reqsk_put(req);
1062
1063	if (unlinked) {
1064		reqsk_queue_removed(&inet_csk(sk)->icsk_accept_queue, req);
1065		reqsk_put(req);
1066	}
1067
1068	return unlinked;
1069}
1070
1071bool inet_csk_reqsk_queue_drop(struct sock *sk, struct request_sock *req)
1072{
1073	return __inet_csk_reqsk_queue_drop(sk, req, false);
1074}
1075EXPORT_SYMBOL(inet_csk_reqsk_queue_drop);
1076
1077void inet_csk_reqsk_queue_drop_and_put(struct sock *sk, struct request_sock *req)
1078{
1079	inet_csk_reqsk_queue_drop(sk, req);
1080	reqsk_put(req);
1081}
1082EXPORT_SYMBOL(inet_csk_reqsk_queue_drop_and_put);
1083
1084static void reqsk_timer_handler(struct timer_list *t)
1085{
1086	struct request_sock *req = from_timer(req, t, rsk_timer);
1087	struct request_sock *nreq = NULL, *oreq = req;
1088	struct sock *sk_listener = req->rsk_listener;
1089	struct inet_connection_sock *icsk;
1090	struct request_sock_queue *queue;
1091	struct net *net;
1092	int max_syn_ack_retries, qlen, expire = 0, resend = 0;
1093
1094	if (inet_sk_state_load(sk_listener) != TCP_LISTEN) {
1095		struct sock *nsk;
1096
1097		nsk = reuseport_migrate_sock(sk_listener, req_to_sk(req), NULL);
1098		if (!nsk)
1099			goto drop;
1100
1101		nreq = inet_reqsk_clone(req, nsk);
1102		if (!nreq)
1103			goto drop;
1104
1105		/* The new timer for the cloned req can decrease the 2
1106		 * by calling inet_csk_reqsk_queue_drop_and_put(), so
1107		 * hold another count to prevent use-after-free and
1108		 * call reqsk_put() just before return.
1109		 */
1110		refcount_set(&nreq->rsk_refcnt, 2 + 1);
1111		timer_setup(&nreq->rsk_timer, reqsk_timer_handler, TIMER_PINNED);
1112		reqsk_queue_migrated(&inet_csk(nsk)->icsk_accept_queue, req);
1113
1114		req = nreq;
1115		sk_listener = nsk;
1116	}
1117
1118	icsk = inet_csk(sk_listener);
1119	net = sock_net(sk_listener);
1120	max_syn_ack_retries = READ_ONCE(icsk->icsk_syn_retries) ? :
1121		READ_ONCE(net->ipv4.sysctl_tcp_synack_retries);
1122	/* Normally all the openreqs are young and become mature
1123	 * (i.e. converted to established socket) for first timeout.
1124	 * If synack was not acknowledged for 1 second, it means
1125	 * one of the following things: synack was lost, ack was lost,
1126	 * rtt is high or nobody planned to ack (i.e. synflood).
1127	 * When server is a bit loaded, queue is populated with old
1128	 * open requests, reducing effective size of queue.
1129	 * When server is well loaded, queue size reduces to zero
1130	 * after several minutes of work. It is not synflood,
1131	 * it is normal operation. The solution is pruning
1132	 * too old entries overriding normal timeout, when
1133	 * situation becomes dangerous.
1134	 *
1135	 * Essentially, we reserve half of room for young
1136	 * embrions; and abort old ones without pity, if old
1137	 * ones are about to clog our table.
1138	 */
1139	queue = &icsk->icsk_accept_queue;
1140	qlen = reqsk_queue_len(queue);
1141	if ((qlen << 1) > max(8U, READ_ONCE(sk_listener->sk_max_ack_backlog))) {
1142		int young = reqsk_queue_len_young(queue) << 1;
1143
1144		while (max_syn_ack_retries > 2) {
1145			if (qlen < young)
1146				break;
1147			max_syn_ack_retries--;
1148			young <<= 1;
1149		}
1150	}
1151	syn_ack_recalc(req, max_syn_ack_retries, READ_ONCE(queue->rskq_defer_accept),
1152		       &expire, &resend);
1153	req->rsk_ops->syn_ack_timeout(req);
1154	if (!expire &&
1155	    (!resend ||
1156	     !inet_rtx_syn_ack(sk_listener, req) ||
1157	     inet_rsk(req)->acked)) {
 
 
1158		if (req->num_timeout++ == 0)
1159			atomic_dec(&queue->young);
1160		mod_timer(&req->rsk_timer, jiffies + reqsk_timeout(req, TCP_RTO_MAX));
1161
1162		if (!nreq)
1163			return;
1164
1165		if (!inet_ehash_insert(req_to_sk(nreq), req_to_sk(oreq), NULL)) {
1166			/* delete timer */
1167			__inet_csk_reqsk_queue_drop(sk_listener, nreq, true);
1168			goto no_ownership;
1169		}
1170
1171		__NET_INC_STATS(net, LINUX_MIB_TCPMIGRATEREQSUCCESS);
1172		reqsk_migrate_reset(oreq);
1173		reqsk_queue_removed(&inet_csk(oreq->rsk_listener)->icsk_accept_queue, oreq);
1174		reqsk_put(oreq);
1175
1176		reqsk_put(nreq);
1177		return;
1178	}
1179
1180	/* Even if we can clone the req, we may need not retransmit any more
1181	 * SYN+ACKs (nreq->num_timeout > max_syn_ack_retries, etc), or another
1182	 * CPU may win the "own_req" race so that inet_ehash_insert() fails.
1183	 */
1184	if (nreq) {
1185		__NET_INC_STATS(net, LINUX_MIB_TCPMIGRATEREQFAILURE);
1186no_ownership:
1187		reqsk_migrate_reset(nreq);
1188		reqsk_queue_removed(queue, nreq);
1189		__reqsk_free(nreq);
1190	}
1191
1192drop:
1193	__inet_csk_reqsk_queue_drop(sk_listener, oreq, true);
1194	reqsk_put(oreq);
1195}
1196
1197static bool reqsk_queue_hash_req(struct request_sock *req,
1198				 unsigned long timeout)
1199{
1200	bool found_dup_sk = false;
1201
1202	if (!inet_ehash_insert(req_to_sk(req), NULL, &found_dup_sk))
1203		return false;
1204
1205	/* The timer needs to be setup after a successful insertion. */
1206	timer_setup(&req->rsk_timer, reqsk_timer_handler, TIMER_PINNED);
1207	mod_timer(&req->rsk_timer, jiffies + timeout);
1208
 
1209	/* before letting lookups find us, make sure all req fields
1210	 * are committed to memory and refcnt initialized.
1211	 */
1212	smp_wmb();
1213	refcount_set(&req->rsk_refcnt, 2 + 1);
1214	return true;
1215}
1216
1217bool inet_csk_reqsk_queue_hash_add(struct sock *sk, struct request_sock *req,
1218				   unsigned long timeout)
1219{
1220	if (!reqsk_queue_hash_req(req, timeout))
1221		return false;
1222
1223	inet_csk_reqsk_queue_added(sk);
1224	return true;
1225}
1226EXPORT_SYMBOL_GPL(inet_csk_reqsk_queue_hash_add);
1227
1228static void inet_clone_ulp(const struct request_sock *req, struct sock *newsk,
1229			   const gfp_t priority)
1230{
1231	struct inet_connection_sock *icsk = inet_csk(newsk);
1232
1233	if (!icsk->icsk_ulp_ops)
1234		return;
1235
1236	icsk->icsk_ulp_ops->clone(req, newsk, priority);
 
1237}
1238
1239/**
1240 *	inet_csk_clone_lock - clone an inet socket, and lock its clone
1241 *	@sk: the socket to clone
1242 *	@req: request_sock
1243 *	@priority: for allocation (%GFP_KERNEL, %GFP_ATOMIC, etc)
1244 *
1245 *	Caller must unlock socket even in error path (bh_unlock_sock(newsk))
1246 */
1247struct sock *inet_csk_clone_lock(const struct sock *sk,
1248				 const struct request_sock *req,
1249				 const gfp_t priority)
1250{
1251	struct sock *newsk = sk_clone_lock(sk, priority);
1252
1253	if (newsk) {
1254		struct inet_connection_sock *newicsk = inet_csk(newsk);
1255
1256		inet_sk_set_state(newsk, TCP_SYN_RECV);
1257		newicsk->icsk_bind_hash = NULL;
1258		newicsk->icsk_bind2_hash = NULL;
1259
1260		inet_sk(newsk)->inet_dport = inet_rsk(req)->ir_rmt_port;
1261		inet_sk(newsk)->inet_num = inet_rsk(req)->ir_num;
1262		inet_sk(newsk)->inet_sport = htons(inet_rsk(req)->ir_num);
1263
1264		/* listeners have SOCK_RCU_FREE, not the children */
1265		sock_reset_flag(newsk, SOCK_RCU_FREE);
1266
1267		inet_sk(newsk)->mc_list = NULL;
1268
1269		newsk->sk_mark = inet_rsk(req)->ir_mark;
1270		atomic64_set(&newsk->sk_cookie,
1271			     atomic64_read(&inet_rsk(req)->ir_cookie));
1272
1273		newicsk->icsk_retransmits = 0;
1274		newicsk->icsk_backoff	  = 0;
1275		newicsk->icsk_probes_out  = 0;
1276		newicsk->icsk_probes_tstamp = 0;
1277
1278		/* Deinitialize accept_queue to trap illegal accesses. */
1279		memset(&newicsk->icsk_accept_queue, 0, sizeof(newicsk->icsk_accept_queue));
1280
1281		inet_clone_ulp(req, newsk, priority);
1282
1283		security_inet_csk_clone(newsk, req);
1284	}
1285	return newsk;
1286}
1287EXPORT_SYMBOL_GPL(inet_csk_clone_lock);
1288
1289/*
1290 * At this point, there should be no process reference to this
1291 * socket, and thus no user references at all.  Therefore we
1292 * can assume the socket waitqueue is inactive and nobody will
1293 * try to jump onto it.
1294 */
1295void inet_csk_destroy_sock(struct sock *sk)
1296{
1297	WARN_ON(sk->sk_state != TCP_CLOSE);
1298	WARN_ON(!sock_flag(sk, SOCK_DEAD));
1299
1300	/* It cannot be in hash table! */
1301	WARN_ON(!sk_unhashed(sk));
1302
1303	/* If it has not 0 inet_sk(sk)->inet_num, it must be bound */
1304	WARN_ON(inet_sk(sk)->inet_num && !inet_csk(sk)->icsk_bind_hash);
1305
1306	sk->sk_prot->destroy(sk);
1307
1308	sk_stream_kill_queues(sk);
1309
1310	xfrm_sk_free_policy(sk);
1311
1312	this_cpu_dec(*sk->sk_prot->orphan_count);
 
 
1313
1314	sock_put(sk);
1315}
1316EXPORT_SYMBOL(inet_csk_destroy_sock);
1317
1318/* This function allows to force a closure of a socket after the call to
1319 * tcp/dccp_create_openreq_child().
1320 */
1321void inet_csk_prepare_forced_close(struct sock *sk)
1322	__releases(&sk->sk_lock.slock)
1323{
1324	/* sk_clone_lock locked the socket and set refcnt to 2 */
1325	bh_unlock_sock(sk);
1326	sock_put(sk);
1327	inet_csk_prepare_for_destroy_sock(sk);
1328	inet_sk(sk)->inet_num = 0;
1329}
1330EXPORT_SYMBOL(inet_csk_prepare_forced_close);
1331
1332static int inet_ulp_can_listen(const struct sock *sk)
1333{
1334	const struct inet_connection_sock *icsk = inet_csk(sk);
1335
1336	if (icsk->icsk_ulp_ops && !icsk->icsk_ulp_ops->clone)
1337		return -EINVAL;
1338
1339	return 0;
1340}
1341
1342int inet_csk_listen_start(struct sock *sk)
1343{
1344	struct inet_connection_sock *icsk = inet_csk(sk);
1345	struct inet_sock *inet = inet_sk(sk);
1346	int err;
1347
1348	err = inet_ulp_can_listen(sk);
1349	if (unlikely(err))
1350		return err;
1351
1352	reqsk_queue_alloc(&icsk->icsk_accept_queue);
1353
1354	sk->sk_ack_backlog = 0;
1355	inet_csk_delack_init(sk);
1356
1357	/* There is race window here: we announce ourselves listening,
1358	 * but this transition is still not validated by get_port().
1359	 * It is OK, because this socket enters to hash table only
1360	 * after validation is complete.
1361	 */
1362	inet_sk_state_store(sk, TCP_LISTEN);
1363	err = sk->sk_prot->get_port(sk, inet->inet_num);
1364	if (!err) {
1365		inet->inet_sport = htons(inet->inet_num);
1366
1367		sk_dst_reset(sk);
1368		err = sk->sk_prot->hash(sk);
1369
1370		if (likely(!err))
1371			return 0;
1372	}
1373
1374	inet_sk_set_state(sk, TCP_CLOSE);
1375	return err;
1376}
1377EXPORT_SYMBOL_GPL(inet_csk_listen_start);
1378
1379static void inet_child_forget(struct sock *sk, struct request_sock *req,
1380			      struct sock *child)
1381{
1382	sk->sk_prot->disconnect(child, O_NONBLOCK);
1383
1384	sock_orphan(child);
1385
1386	this_cpu_inc(*sk->sk_prot->orphan_count);
1387
1388	if (sk->sk_protocol == IPPROTO_TCP && tcp_rsk(req)->tfo_listener) {
1389		BUG_ON(rcu_access_pointer(tcp_sk(child)->fastopen_rsk) != req);
1390		BUG_ON(sk != req->rsk_listener);
1391
1392		/* Paranoid, to prevent race condition if
1393		 * an inbound pkt destined for child is
1394		 * blocked by sock lock in tcp_v4_rcv().
1395		 * Also to satisfy an assertion in
1396		 * tcp_v4_destroy_sock().
1397		 */
1398		RCU_INIT_POINTER(tcp_sk(child)->fastopen_rsk, NULL);
1399	}
1400	inet_csk_destroy_sock(child);
1401}
1402
1403struct sock *inet_csk_reqsk_queue_add(struct sock *sk,
1404				      struct request_sock *req,
1405				      struct sock *child)
1406{
1407	struct request_sock_queue *queue = &inet_csk(sk)->icsk_accept_queue;
1408
1409	spin_lock(&queue->rskq_lock);
1410	if (unlikely(sk->sk_state != TCP_LISTEN)) {
1411		inet_child_forget(sk, req, child);
1412		child = NULL;
1413	} else {
1414		req->sk = child;
1415		req->dl_next = NULL;
1416		if (queue->rskq_accept_head == NULL)
1417			WRITE_ONCE(queue->rskq_accept_head, req);
1418		else
1419			queue->rskq_accept_tail->dl_next = req;
1420		queue->rskq_accept_tail = req;
1421		sk_acceptq_added(sk);
1422	}
1423	spin_unlock(&queue->rskq_lock);
1424	return child;
1425}
1426EXPORT_SYMBOL(inet_csk_reqsk_queue_add);
1427
1428struct sock *inet_csk_complete_hashdance(struct sock *sk, struct sock *child,
1429					 struct request_sock *req, bool own_req)
1430{
1431	if (own_req) {
1432		inet_csk_reqsk_queue_drop(req->rsk_listener, req);
1433		reqsk_queue_removed(&inet_csk(req->rsk_listener)->icsk_accept_queue, req);
1434
1435		if (sk != req->rsk_listener) {
1436			/* another listening sk has been selected,
1437			 * migrate the req to it.
1438			 */
1439			struct request_sock *nreq;
1440
1441			/* hold a refcnt for the nreq->rsk_listener
1442			 * which is assigned in inet_reqsk_clone()
1443			 */
1444			sock_hold(sk);
1445			nreq = inet_reqsk_clone(req, sk);
1446			if (!nreq) {
1447				inet_child_forget(sk, req, child);
1448				goto child_put;
1449			}
1450
1451			refcount_set(&nreq->rsk_refcnt, 1);
1452			if (inet_csk_reqsk_queue_add(sk, nreq, child)) {
1453				__NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMIGRATEREQSUCCESS);
1454				reqsk_migrate_reset(req);
1455				reqsk_put(req);
1456				return child;
1457			}
1458
1459			__NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMIGRATEREQFAILURE);
1460			reqsk_migrate_reset(nreq);
1461			__reqsk_free(nreq);
1462		} else if (inet_csk_reqsk_queue_add(sk, req, child)) {
1463			return child;
1464		}
1465	}
1466	/* Too bad, another child took ownership of the request, undo. */
1467child_put:
1468	bh_unlock_sock(child);
1469	sock_put(child);
1470	return NULL;
1471}
1472EXPORT_SYMBOL(inet_csk_complete_hashdance);
1473
1474/*
1475 *	This routine closes sockets which have been at least partially
1476 *	opened, but not yet accepted.
1477 */
1478void inet_csk_listen_stop(struct sock *sk)
1479{
1480	struct inet_connection_sock *icsk = inet_csk(sk);
1481	struct request_sock_queue *queue = &icsk->icsk_accept_queue;
1482	struct request_sock *next, *req;
1483
1484	/* Following specs, it would be better either to send FIN
1485	 * (and enter FIN-WAIT-1, it is normal close)
1486	 * or to send active reset (abort).
1487	 * Certainly, it is pretty dangerous while synflood, but it is
1488	 * bad justification for our negligence 8)
1489	 * To be honest, we are not able to make either
1490	 * of the variants now.			--ANK
1491	 */
1492	while ((req = reqsk_queue_remove(queue, sk)) != NULL) {
1493		struct sock *child = req->sk, *nsk;
1494		struct request_sock *nreq;
1495
1496		local_bh_disable();
1497		bh_lock_sock(child);
1498		WARN_ON(sock_owned_by_user(child));
1499		sock_hold(child);
1500
1501		nsk = reuseport_migrate_sock(sk, child, NULL);
1502		if (nsk) {
1503			nreq = inet_reqsk_clone(req, nsk);
1504			if (nreq) {
1505				refcount_set(&nreq->rsk_refcnt, 1);
1506
1507				if (inet_csk_reqsk_queue_add(nsk, nreq, child)) {
1508					__NET_INC_STATS(sock_net(nsk),
1509							LINUX_MIB_TCPMIGRATEREQSUCCESS);
1510					reqsk_migrate_reset(req);
1511				} else {
1512					__NET_INC_STATS(sock_net(nsk),
1513							LINUX_MIB_TCPMIGRATEREQFAILURE);
1514					reqsk_migrate_reset(nreq);
1515					__reqsk_free(nreq);
1516				}
1517
1518				/* inet_csk_reqsk_queue_add() has already
1519				 * called inet_child_forget() on failure case.
1520				 */
1521				goto skip_child_forget;
1522			}
1523		}
1524
1525		inet_child_forget(sk, req, child);
1526skip_child_forget:
1527		reqsk_put(req);
1528		bh_unlock_sock(child);
1529		local_bh_enable();
1530		sock_put(child);
1531
1532		cond_resched();
1533	}
1534	if (queue->fastopenq.rskq_rst_head) {
1535		/* Free all the reqs queued in rskq_rst_head. */
1536		spin_lock_bh(&queue->fastopenq.lock);
1537		req = queue->fastopenq.rskq_rst_head;
1538		queue->fastopenq.rskq_rst_head = NULL;
1539		spin_unlock_bh(&queue->fastopenq.lock);
1540		while (req != NULL) {
1541			next = req->dl_next;
1542			reqsk_put(req);
1543			req = next;
1544		}
1545	}
1546	WARN_ON_ONCE(sk->sk_ack_backlog);
1547}
1548EXPORT_SYMBOL_GPL(inet_csk_listen_stop);
1549
1550void inet_csk_addr2sockaddr(struct sock *sk, struct sockaddr *uaddr)
1551{
1552	struct sockaddr_in *sin = (struct sockaddr_in *)uaddr;
1553	const struct inet_sock *inet = inet_sk(sk);
1554
1555	sin->sin_family		= AF_INET;
1556	sin->sin_addr.s_addr	= inet->inet_daddr;
1557	sin->sin_port		= inet->inet_dport;
1558}
1559EXPORT_SYMBOL_GPL(inet_csk_addr2sockaddr);
1560
1561static struct dst_entry *inet_csk_rebuild_route(struct sock *sk, struct flowi *fl)
1562{
1563	const struct inet_sock *inet = inet_sk(sk);
1564	const struct ip_options_rcu *inet_opt;
1565	__be32 daddr = inet->inet_daddr;
1566	struct flowi4 *fl4;
1567	struct rtable *rt;
1568
1569	rcu_read_lock();
1570	inet_opt = rcu_dereference(inet->inet_opt);
1571	if (inet_opt && inet_opt->opt.srr)
1572		daddr = inet_opt->opt.faddr;
1573	fl4 = &fl->u.ip4;
1574	rt = ip_route_output_ports(sock_net(sk), fl4, sk, daddr,
1575				   inet->inet_saddr, inet->inet_dport,
1576				   inet->inet_sport, sk->sk_protocol,
1577				   ip_sock_rt_tos(sk), sk->sk_bound_dev_if);
1578	if (IS_ERR(rt))
1579		rt = NULL;
1580	if (rt)
1581		sk_setup_caps(sk, &rt->dst);
1582	rcu_read_unlock();
1583
1584	return &rt->dst;
1585}
1586
1587struct dst_entry *inet_csk_update_pmtu(struct sock *sk, u32 mtu)
1588{
1589	struct dst_entry *dst = __sk_dst_check(sk, 0);
1590	struct inet_sock *inet = inet_sk(sk);
1591
1592	if (!dst) {
1593		dst = inet_csk_rebuild_route(sk, &inet->cork.fl);
1594		if (!dst)
1595			goto out;
1596	}
1597	dst->ops->update_pmtu(dst, sk, NULL, mtu, true);
1598
1599	dst = __sk_dst_check(sk, 0);
1600	if (!dst)
1601		dst = inet_csk_rebuild_route(sk, &inet->cork.fl);
1602out:
1603	return dst;
1604}
1605EXPORT_SYMBOL_GPL(inet_csk_update_pmtu);