af_unix.c 67.7 KB
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/*
 * NET4:	Implementation of BSD Unix domain sockets.
 *
4
 * Authors:	Alan Cox, <alan@lxorguk.ukuu.org.uk>
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 *
 *		This program is free software; you can redistribute it and/or
 *		modify it under the terms of the GNU General Public License
 *		as published by the Free Software Foundation; either version
 *		2 of the License, or (at your option) any later version.
 *
 * Fixes:
 *		Linus Torvalds	:	Assorted bug cures.
 *		Niibe Yutaka	:	async I/O support.
 *		Carsten Paeth	:	PF_UNIX check, address fixes.
 *		Alan Cox	:	Limit size of allocated blocks.
 *		Alan Cox	:	Fixed the stupid socketpair bug.
 *		Alan Cox	:	BSD compatibility fine tuning.
 *		Alan Cox	:	Fixed a bug in connect when interrupted.
 *		Alan Cox	:	Sorted out a proper draft version of
 *					file descriptor passing hacked up from
 *					Mike Shaver's work.
 *		Marty Leisner	:	Fixes to fd passing
 *		Nick Nevin	:	recvmsg bugfix.
 *		Alan Cox	:	Started proper garbage collector
 *		Heiko EiBfeldt	:	Missing verify_area check
 *		Alan Cox	:	Started POSIXisms
 *		Andreas Schwab	:	Replace inode by dentry for proper
 *					reference counting
 *		Kirk Petersen	:	Made this a module
 *	    Christoph Rohland	:	Elegant non-blocking accept/connect algorithm.
 *					Lots of bug fixes.
 *	     Alexey Kuznetosv	:	Repaired (I hope) bugs introduces
 *					by above two patches.
 *	     Andrea Arcangeli	:	If possible we block in connect(2)
 *					if the max backlog of the listen socket
 *					is been reached. This won't break
 *					old apps and it will avoid huge amount
 *					of socks hashed (this for unix_gc()
 *					performances reasons).
 *					Security fix that limits the max
 *					number of socks to 2*max_files and
 *					the number of skb queueable in the
 *					dgram receiver.
 *		Artur Skawina   :	Hash function optimizations
 *	     Alexey Kuznetsov   :	Full scale SMP. Lot of bugs are introduced 8)
 *	      Malcolm Beattie   :	Set peercred for socketpair
 *	     Michal Ostrowski   :       Module initialization cleanup.
 *	     Arnaldo C. Melo	:	Remove MOD_{INC,DEC}_USE_COUNT,
 *	     				the core infrastructure is doing that
 *	     				for all net proto families now (2.5.69+)
 *
 *
 * Known differences from reference BSD that was tested:
 *
 *	[TO FIX]
 *	ECONNREFUSED is not returned from one end of a connected() socket to the
 *		other the moment one end closes.
 *	fstat() doesn't return st_dev=0, and give the blksize as high water mark
 *		and a fake inode identifier (nor the BSD first socket fstat twice bug).
 *	[NOT TO FIX]
 *	accept() returns a path name even if the connecting socket has closed
 *		in the meantime (BSD loses the path and gives up).
 *	accept() returns 0 length path for an unbound connector. BSD returns 16
 *		and a null first byte in the path (but not for gethost/peername - BSD bug ??)
 *	socketpair(...SOCK_RAW..) doesn't panic the kernel.
 *	BSD af_unix apparently has connect forgetting to block properly.
 *		(need to check this with the POSIX spec in detail)
 *
 * Differences from 2.0.0-11-... (ANK)
 *	Bug fixes and improvements.
 *		- client shutdown killed server socket.
 *		- removed all useless cli/sti pairs.
 *
 *	Semantic changes/extensions.
 *		- generic control message passing.
 *		- SCM_CREDENTIALS control message.
 *		- "Abstract" (not FS based) socket bindings.
 *		  Abstract names are sequences of bytes (not zero terminated)
 *		  started by 0, so that this name space does not intersect
 *		  with BSD names.
 */

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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

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#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/stat.h>
#include <linux/dcache.h>
#include <linux/namei.h>
#include <linux/socket.h>
#include <linux/un.h>
#include <linux/fcntl.h>
#include <linux/termios.h>
#include <linux/sockios.h>
#include <linux/net.h>
#include <linux/in.h>
#include <linux/fs.h>
#include <linux/slab.h>
#include <asm/uaccess.h>
#include <linux/skbuff.h>
#include <linux/netdevice.h>
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#include <net/net_namespace.h>
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#include <net/sock.h>
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#include <net/tcp_states.h>
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#include <net/af_unix.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <net/scm.h>
#include <linux/init.h>
#include <linux/poll.h>
#include <linux/rtnetlink.h>
#include <linux/mount.h>
#include <net/checksum.h>
#include <linux/security.h>
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#include <linux/freezer.h>
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struct hlist_head unix_socket_table[2 * UNIX_HASH_SIZE];
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EXPORT_SYMBOL_GPL(unix_socket_table);
DEFINE_SPINLOCK(unix_table_lock);
EXPORT_SYMBOL_GPL(unix_table_lock);
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static atomic_long_t unix_nr_socks;
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static struct hlist_head *unix_sockets_unbound(void *addr)
{
	unsigned long hash = (unsigned long)addr;

	hash ^= hash >> 16;
	hash ^= hash >> 8;
	hash %= UNIX_HASH_SIZE;
	return &unix_socket_table[UNIX_HASH_SIZE + hash];
}

#define UNIX_ABSTRACT(sk)	(unix_sk(sk)->addr->hash < UNIX_HASH_SIZE)
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#ifdef CONFIG_SECURITY_NETWORK
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static void unix_get_secdata(struct scm_cookie *scm, struct sk_buff *skb)
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{
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	UNIXCB(skb).secid = scm->secid;
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}

static inline void unix_set_secdata(struct scm_cookie *scm, struct sk_buff *skb)
{
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	scm->secid = UNIXCB(skb).secid;
}

static inline bool unix_secdata_eq(struct scm_cookie *scm, struct sk_buff *skb)
{
	return (scm->secid == UNIXCB(skb).secid);
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}
#else
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static inline void unix_get_secdata(struct scm_cookie *scm, struct sk_buff *skb)
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{ }

static inline void unix_set_secdata(struct scm_cookie *scm, struct sk_buff *skb)
{ }
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static inline bool unix_secdata_eq(struct scm_cookie *scm, struct sk_buff *skb)
{
	return true;
}
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#endif /* CONFIG_SECURITY_NETWORK */

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/*
 *  SMP locking strategy:
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 *    hash table is protected with spinlock unix_table_lock
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 *    each socket state is protected by separate spin lock.
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 */

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static inline unsigned int unix_hash_fold(__wsum n)
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{
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	unsigned int hash = (__force unsigned int)csum_fold(n);
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	hash ^= hash>>8;
	return hash&(UNIX_HASH_SIZE-1);
}

#define unix_peer(sk) (unix_sk(sk)->peer)

static inline int unix_our_peer(struct sock *sk, struct sock *osk)
{
	return unix_peer(osk) == sk;
}

static inline int unix_may_send(struct sock *sk, struct sock *osk)
{
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	return unix_peer(osk) == NULL || unix_our_peer(sk, osk);
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}

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static inline int unix_recvq_full(struct sock const *sk)
{
	return skb_queue_len(&sk->sk_receive_queue) > sk->sk_max_ack_backlog;
}

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struct sock *unix_peer_get(struct sock *s)
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{
	struct sock *peer;

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	unix_state_lock(s);
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	peer = unix_peer(s);
	if (peer)
		sock_hold(peer);
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	unix_state_unlock(s);
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	return peer;
}
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EXPORT_SYMBOL_GPL(unix_peer_get);
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static inline void unix_release_addr(struct unix_address *addr)
{
	if (atomic_dec_and_test(&addr->refcnt))
		kfree(addr);
}

/*
 *	Check unix socket name:
 *		- should be not zero length.
 *	        - if started by not zero, should be NULL terminated (FS object)
 *		- if started by zero, it is abstract name.
 */
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static int unix_mkname(struct sockaddr_un *sunaddr, int len, unsigned int *hashp)
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{
	if (len <= sizeof(short) || len > sizeof(*sunaddr))
		return -EINVAL;
	if (!sunaddr || sunaddr->sun_family != AF_UNIX)
		return -EINVAL;
	if (sunaddr->sun_path[0]) {
		/*
		 * This may look like an off by one error but it is a bit more
		 * subtle. 108 is the longest valid AF_UNIX path for a binding.
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		 * sun_path[108] doesn't as such exist.  However in kernel space
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		 * we are guaranteed that it is a valid memory location in our
		 * kernel address buffer.
		 */
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		((char *)sunaddr)[len] = 0;
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		len = strlen(sunaddr->sun_path)+1+sizeof(short);
		return len;
	}

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	*hashp = unix_hash_fold(csum_partial(sunaddr, len, 0));
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	return len;
}

static void __unix_remove_socket(struct sock *sk)
{
	sk_del_node_init(sk);
}

static void __unix_insert_socket(struct hlist_head *list, struct sock *sk)
{
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	WARN_ON(!sk_unhashed(sk));
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	sk_add_node(sk, list);
}

static inline void unix_remove_socket(struct sock *sk)
{
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	spin_lock(&unix_table_lock);
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	__unix_remove_socket(sk);
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	spin_unlock(&unix_table_lock);
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}

static inline void unix_insert_socket(struct hlist_head *list, struct sock *sk)
{
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	spin_lock(&unix_table_lock);
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	__unix_insert_socket(list, sk);
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	spin_unlock(&unix_table_lock);
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}

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static struct sock *__unix_find_socket_byname(struct net *net,
					      struct sockaddr_un *sunname,
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					      int len, int type, unsigned int hash)
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{
	struct sock *s;

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	sk_for_each(s, &unix_socket_table[hash ^ type]) {
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		struct unix_sock *u = unix_sk(s);

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		if (!net_eq(sock_net(s), net))
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			continue;

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		if (u->addr->len == len &&
		    !memcmp(u->addr->name, sunname, len))
			goto found;
	}
	s = NULL;
found:
	return s;
}

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static inline struct sock *unix_find_socket_byname(struct net *net,
						   struct sockaddr_un *sunname,
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						   int len, int type,
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						   unsigned int hash)
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{
	struct sock *s;

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	spin_lock(&unix_table_lock);
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	s = __unix_find_socket_byname(net, sunname, len, type, hash);
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	if (s)
		sock_hold(s);
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	spin_unlock(&unix_table_lock);
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	return s;
}

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static struct sock *unix_find_socket_byinode(struct inode *i)
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{
	struct sock *s;

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	spin_lock(&unix_table_lock);
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	sk_for_each(s,
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		    &unix_socket_table[i->i_ino & (UNIX_HASH_SIZE - 1)]) {
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		struct dentry *dentry = unix_sk(s)->path.dentry;
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		if (dentry && d_backing_inode(dentry) == i) {
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			sock_hold(s);
			goto found;
		}
	}
	s = NULL;
found:
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	spin_unlock(&unix_table_lock);
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	return s;
}

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/* Support code for asymmetrically connected dgram sockets
 *
 * If a datagram socket is connected to a socket not itself connected
 * to the first socket (eg, /dev/log), clients may only enqueue more
 * messages if the present receive queue of the server socket is not
 * "too large". This means there's a second writeability condition
 * poll and sendmsg need to test. The dgram recv code will do a wake
 * up on the peer_wait wait queue of a socket upon reception of a
 * datagram which needs to be propagated to sleeping would-be writers
 * since these might not have sent anything so far. This can't be
 * accomplished via poll_wait because the lifetime of the server
 * socket might be less than that of its clients if these break their
 * association with it or if the server socket is closed while clients
 * are still connected to it and there's no way to inform "a polling
 * implementation" that it should let go of a certain wait queue
 *
 * In order to propagate a wake up, a wait_queue_t of the client
 * socket is enqueued on the peer_wait queue of the server socket
 * whose wake function does a wake_up on the ordinary client socket
 * wait queue. This connection is established whenever a write (or
 * poll for write) hit the flow control condition and broken when the
 * association to the server socket is dissolved or after a wake up
 * was relayed.
 */

static int unix_dgram_peer_wake_relay(wait_queue_t *q, unsigned mode, int flags,
				      void *key)
{
	struct unix_sock *u;
	wait_queue_head_t *u_sleep;

	u = container_of(q, struct unix_sock, peer_wake);

	__remove_wait_queue(&unix_sk(u->peer_wake.private)->peer_wait,
			    q);
	u->peer_wake.private = NULL;

	/* relaying can only happen while the wq still exists */
	u_sleep = sk_sleep(&u->sk);
	if (u_sleep)
		wake_up_interruptible_poll(u_sleep, key);

	return 0;
}

static int unix_dgram_peer_wake_connect(struct sock *sk, struct sock *other)
{
	struct unix_sock *u, *u_other;
	int rc;

	u = unix_sk(sk);
	u_other = unix_sk(other);
	rc = 0;
	spin_lock(&u_other->peer_wait.lock);

	if (!u->peer_wake.private) {
		u->peer_wake.private = other;
		__add_wait_queue(&u_other->peer_wait, &u->peer_wake);

		rc = 1;
	}

	spin_unlock(&u_other->peer_wait.lock);
	return rc;
}

static void unix_dgram_peer_wake_disconnect(struct sock *sk,
					    struct sock *other)
{
	struct unix_sock *u, *u_other;

	u = unix_sk(sk);
	u_other = unix_sk(other);
	spin_lock(&u_other->peer_wait.lock);

	if (u->peer_wake.private == other) {
		__remove_wait_queue(&u_other->peer_wait, &u->peer_wake);
		u->peer_wake.private = NULL;
	}

	spin_unlock(&u_other->peer_wait.lock);
}

static void unix_dgram_peer_wake_disconnect_wakeup(struct sock *sk,
						   struct sock *other)
{
	unix_dgram_peer_wake_disconnect(sk, other);
	wake_up_interruptible_poll(sk_sleep(sk),
				   POLLOUT |
				   POLLWRNORM |
				   POLLWRBAND);
}

/* preconditions:
 *	- unix_peer(sk) == other
 *	- association is stable
 */
static int unix_dgram_peer_wake_me(struct sock *sk, struct sock *other)
{
	int connected;

	connected = unix_dgram_peer_wake_connect(sk, other);

	if (unix_recvq_full(other))
		return 1;

	if (connected)
		unix_dgram_peer_wake_disconnect(sk, other);

	return 0;
}

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static inline int unix_writable(struct sock *sk)
{
	return (atomic_read(&sk->sk_wmem_alloc) << 2) <= sk->sk_sndbuf;
}

static void unix_write_space(struct sock *sk)
{
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	struct socket_wq *wq;

	rcu_read_lock();
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	if (unix_writable(sk)) {
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		wq = rcu_dereference(sk->sk_wq);
		if (wq_has_sleeper(wq))
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			wake_up_interruptible_sync_poll(&wq->wait,
				POLLOUT | POLLWRNORM | POLLWRBAND);
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		sk_wake_async(sk, SOCK_WAKE_SPACE, POLL_OUT);
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	}
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	rcu_read_unlock();
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}

/* When dgram socket disconnects (or changes its peer), we clear its receive
 * queue of packets arrived from previous peer. First, it allows to do
 * flow control based only on wmem_alloc; second, sk connected to peer
 * may receive messages only from that peer. */
static void unix_dgram_disconnected(struct sock *sk, struct sock *other)
{
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	if (!skb_queue_empty(&sk->sk_receive_queue)) {
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		skb_queue_purge(&sk->sk_receive_queue);
		wake_up_interruptible_all(&unix_sk(sk)->peer_wait);

		/* If one link of bidirectional dgram pipe is disconnected,
		 * we signal error. Messages are lost. Do not make this,
		 * when peer was not connected to us.
		 */
		if (!sock_flag(other, SOCK_DEAD) && unix_peer(other) == sk) {
			other->sk_err = ECONNRESET;
			other->sk_error_report(other);
		}
	}
}

static void unix_sock_destructor(struct sock *sk)
{
	struct unix_sock *u = unix_sk(sk);

	skb_queue_purge(&sk->sk_receive_queue);

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	WARN_ON(atomic_read(&sk->sk_wmem_alloc));
	WARN_ON(!sk_unhashed(sk));
	WARN_ON(sk->sk_socket);
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	if (!sock_flag(sk, SOCK_DEAD)) {
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		pr_info("Attempt to release alive unix socket: %p\n", sk);
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		return;
	}

	if (u->addr)
		unix_release_addr(u->addr);

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	atomic_long_dec(&unix_nr_socks);
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	local_bh_disable();
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	sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
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	local_bh_enable();
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#ifdef UNIX_REFCNT_DEBUG
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	pr_debug("UNIX %p is destroyed, %ld are still alive.\n", sk,
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		atomic_long_read(&unix_nr_socks));
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#endif
}

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static void unix_release_sock(struct sock *sk, int embrion)
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{
	struct unix_sock *u = unix_sk(sk);
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	struct path path;
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	struct sock *skpair;
	struct sk_buff *skb;
	int state;

	unix_remove_socket(sk);

	/* Clear state */
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	unix_state_lock(sk);
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	sock_orphan(sk);
	sk->sk_shutdown = SHUTDOWN_MASK;
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	path	     = u->path;
	u->path.dentry = NULL;
	u->path.mnt = NULL;
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	state = sk->sk_state;
	sk->sk_state = TCP_CLOSE;
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	unix_state_unlock(sk);
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	wake_up_interruptible_all(&u->peer_wait);

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	skpair = unix_peer(sk);
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	if (skpair != NULL) {
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		if (sk->sk_type == SOCK_STREAM || sk->sk_type == SOCK_SEQPACKET) {
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			unix_state_lock(skpair);
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			/* No more writes */
			skpair->sk_shutdown = SHUTDOWN_MASK;
			if (!skb_queue_empty(&sk->sk_receive_queue) || embrion)
				skpair->sk_err = ECONNRESET;
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			unix_state_unlock(skpair);
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			skpair->sk_state_change(skpair);
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			sk_wake_async(skpair, SOCK_WAKE_WAITD, POLL_HUP);
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		}
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		unix_dgram_peer_wake_disconnect(sk, skpair);
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		sock_put(skpair); /* It may now die */
		unix_peer(sk) = NULL;
	}

	/* Try to flush out this socket. Throw out buffers at least */

	while ((skb = skb_dequeue(&sk->sk_receive_queue)) != NULL) {
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		if (state == TCP_LISTEN)
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			unix_release_sock(skb->sk, 1);
		/* passed fds are erased in the kfree_skb hook	      */
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		UNIXCB(skb).consumed = skb->len;
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		kfree_skb(skb);
	}

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	if (path.dentry)
		path_put(&path);
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	sock_put(sk);

	/* ---- Socket is dead now and most probably destroyed ---- */

	/*
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	 * Fixme: BSD difference: In BSD all sockets connected to us get
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	 *	  ECONNRESET and we die on the spot. In Linux we behave
	 *	  like files and pipes do and wait for the last
	 *	  dereference.
	 *
	 * Can't we simply set sock->err?
	 *
	 *	  What the above comment does talk about? --ANK(980817)
	 */

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	if (unix_tot_inflight)
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		unix_gc();		/* Garbage collect fds */
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}

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static void init_peercred(struct sock *sk)
{
	put_pid(sk->sk_peer_pid);
	if (sk->sk_peer_cred)
		put_cred(sk->sk_peer_cred);
	sk->sk_peer_pid  = get_pid(task_tgid(current));
	sk->sk_peer_cred = get_current_cred();
}

static void copy_peercred(struct sock *sk, struct sock *peersk)
{
	put_pid(sk->sk_peer_pid);
	if (sk->sk_peer_cred)
		put_cred(sk->sk_peer_cred);
	sk->sk_peer_pid  = get_pid(peersk->sk_peer_pid);
	sk->sk_peer_cred = get_cred(peersk->sk_peer_cred);
}

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static int unix_listen(struct socket *sock, int backlog)
{
	int err;
	struct sock *sk = sock->sk;
	struct unix_sock *u = unix_sk(sk);
606
	struct pid *old_pid = NULL;
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	err = -EOPNOTSUPP;
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	if (sock->type != SOCK_STREAM && sock->type != SOCK_SEQPACKET)
		goto out;	/* Only stream/seqpacket sockets accept */
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	err = -EINVAL;
	if (!u->addr)
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		goto out;	/* No listens on an unbound socket */
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	unix_state_lock(sk);
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	if (sk->sk_state != TCP_CLOSE && sk->sk_state != TCP_LISTEN)
		goto out_unlock;
	if (backlog > sk->sk_max_ack_backlog)
		wake_up_interruptible_all(&u->peer_wait);
	sk->sk_max_ack_backlog	= backlog;
	sk->sk_state		= TCP_LISTEN;
	/* set credentials so connect can copy them */
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	init_peercred(sk);
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	err = 0;

out_unlock:
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	unix_state_unlock(sk);
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	put_pid(old_pid);
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out:
	return err;
}

static int unix_release(struct socket *);
static int unix_bind(struct socket *, struct sockaddr *, int);
static int unix_stream_connect(struct socket *, struct sockaddr *,
			       int addr_len, int flags);
static int unix_socketpair(struct socket *, struct socket *);
static int unix_accept(struct socket *, struct socket *, int);
static int unix_getname(struct socket *, struct sockaddr *, int *, int);
static unsigned int unix_poll(struct file *, struct socket *, poll_table *);
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static unsigned int unix_dgram_poll(struct file *, struct socket *,
				    poll_table *);
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static int unix_ioctl(struct socket *, unsigned int, unsigned long);
static int unix_shutdown(struct socket *, int);
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static int unix_stream_sendmsg(struct socket *, struct msghdr *, size_t);
static int unix_stream_recvmsg(struct socket *, struct msghdr *, size_t, int);
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static ssize_t unix_stream_sendpage(struct socket *, struct page *, int offset,
				    size_t size, int flags);
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static ssize_t unix_stream_splice_read(struct socket *,  loff_t *ppos,
				       struct pipe_inode_info *, size_t size,
				       unsigned int flags);
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static int unix_dgram_sendmsg(struct socket *, struct msghdr *, size_t);
static int unix_dgram_recvmsg(struct socket *, struct msghdr *, size_t, int);
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static int unix_dgram_connect(struct socket *, struct sockaddr *,
			      int, int);
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static int unix_seqpacket_sendmsg(struct socket *, struct msghdr *, size_t);
static int unix_seqpacket_recvmsg(struct socket *, struct msghdr *, size_t,
				  int);
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static int unix_set_peek_off(struct sock *sk, int val)
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{
	struct unix_sock *u = unix_sk(sk);

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	if (mutex_lock_interruptible(&u->readlock))
		return -EINTR;

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	sk->sk_peek_off = val;
	mutex_unlock(&u->readlock);
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	return 0;
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}


673
static const struct proto_ops unix_stream_ops = {
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	.family =	PF_UNIX,
	.owner =	THIS_MODULE,
	.release =	unix_release,
	.bind =		unix_bind,
	.connect =	unix_stream_connect,
	.socketpair =	unix_socketpair,
	.accept =	unix_accept,
	.getname =	unix_getname,
	.poll =		unix_poll,
	.ioctl =	unix_ioctl,
	.listen =	unix_listen,
	.shutdown =	unix_shutdown,
	.setsockopt =	sock_no_setsockopt,
	.getsockopt =	sock_no_getsockopt,
	.sendmsg =	unix_stream_sendmsg,
	.recvmsg =	unix_stream_recvmsg,
	.mmap =		sock_no_mmap,
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	.sendpage =	unix_stream_sendpage,
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	.splice_read =	unix_stream_splice_read,
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	.set_peek_off =	unix_set_peek_off,
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};

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static const struct proto_ops unix_dgram_ops = {
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	.family =	PF_UNIX,
	.owner =	THIS_MODULE,
	.release =	unix_release,
	.bind =		unix_bind,
	.connect =	unix_dgram_connect,
	.socketpair =	unix_socketpair,
	.accept =	sock_no_accept,
	.getname =	unix_getname,
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	.poll =		unix_dgram_poll,
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	.ioctl =	unix_ioctl,
	.listen =	sock_no_listen,
	.shutdown =	unix_shutdown,
	.setsockopt =	sock_no_setsockopt,
	.getsockopt =	sock_no_getsockopt,
	.sendmsg =	unix_dgram_sendmsg,
	.recvmsg =	unix_dgram_recvmsg,
	.mmap =		sock_no_mmap,
	.sendpage =	sock_no_sendpage,
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	.set_peek_off =	unix_set_peek_off,
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};

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static const struct proto_ops unix_seqpacket_ops = {
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	.family =	PF_UNIX,
	.owner =	THIS_MODULE,
	.release =	unix_release,
	.bind =		unix_bind,
	.connect =	unix_stream_connect,
	.socketpair =	unix_socketpair,
	.accept =	unix_accept,
	.getname =	unix_getname,
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	.poll =		unix_dgram_poll,
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	.ioctl =	unix_ioctl,
	.listen =	unix_listen,
	.shutdown =	unix_shutdown,
	.setsockopt =	sock_no_setsockopt,
	.getsockopt =	sock_no_getsockopt,
	.sendmsg =	unix_seqpacket_sendmsg,
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	.recvmsg =	unix_seqpacket_recvmsg,
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	.mmap =		sock_no_mmap,
	.sendpage =	sock_no_sendpage,
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	.set_peek_off =	unix_set_peek_off,
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};

static struct proto unix_proto = {
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	.name			= "UNIX",
	.owner			= THIS_MODULE,
	.obj_size		= sizeof(struct unix_sock),
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};

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/*
 * AF_UNIX sockets do not interact with hardware, hence they
 * dont trigger interrupts - so it's safe for them to have
 * bh-unsafe locking for their sk_receive_queue.lock. Split off
 * this special lock-class by reinitializing the spinlock key:
 */
static struct lock_class_key af_unix_sk_receive_queue_lock_key;

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static struct sock *unix_create1(struct net *net, struct socket *sock, int kern)
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{
	struct sock *sk = NULL;
	struct unix_sock *u;

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	atomic_long_inc(&unix_nr_socks);
	if (atomic_long_read(&unix_nr_socks) > 2 * get_max_files())
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		goto out;

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	sk = sk_alloc(net, PF_UNIX, GFP_KERNEL, &unix_proto, kern);
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	if (!sk)
		goto out;

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	sock_init_data(sock, sk);
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	lockdep_set_class(&sk->sk_receive_queue.lock,
				&af_unix_sk_receive_queue_lock_key);
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	sk->sk_write_space	= unix_write_space;
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	sk->sk_max_ack_backlog	= net->unx.sysctl_max_dgram_qlen;
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	sk->sk_destruct		= unix_sock_destructor;
	u	  = unix_sk(sk);
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	u->path.dentry = NULL;
	u->path.mnt = NULL;
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	spin_lock_init(&u->lock);
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	atomic_long_set(&u->inflight, 0);
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	INIT_LIST_HEAD(&u->link);
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	mutex_init(&u->readlock); /* single task reading lock */
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	init_waitqueue_head(&u->peer_wait);
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	init_waitqueue_func_entry(&u->peer_wake, unix_dgram_peer_wake_relay);
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	unix_insert_socket(unix_sockets_unbound(sk), sk);
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out:
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	if (sk == NULL)
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		atomic_long_dec(&unix_nr_socks);
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	else {
		local_bh_disable();
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		sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
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		local_bh_enable();
	}
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	return sk;
}

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static int unix_create(struct net *net, struct socket *sock, int protocol,
		       int kern)
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{
	if (protocol && protocol != PF_UNIX)
		return -EPROTONOSUPPORT;

	sock->state = SS_UNCONNECTED;

	switch (sock->type) {
	case SOCK_STREAM:
		sock->ops = &unix_stream_ops;
		break;
		/*
		 *	Believe it or not BSD has AF_UNIX, SOCK_RAW though
		 *	nothing uses it.
		 */
	case SOCK_RAW:
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		sock->type = SOCK_DGRAM;
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	case SOCK_DGRAM:
		sock->ops = &unix_dgram_ops;
		break;
	case SOCK_SEQPACKET:
		sock->ops = &unix_seqpacket_ops;
		break;
	default:
		return -ESOCKTNOSUPPORT;
	}

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	return unix_create1(net, sock, kern) ? 0 : -ENOMEM;
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}

static int unix_release(struct socket *sock)
{
	struct sock *sk = sock->sk;

	if (!sk)
		return 0;

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	unix_release_sock(sk, 0);
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	sock->sk = NULL;

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	return 0;
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}

static int unix_autobind(struct socket *sock)
{
	struct sock *sk = sock->sk;
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	struct net *net = sock_net(sk);
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	struct unix_sock *u = unix_sk(sk);
	static u32 ordernum = 1;
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	struct unix_address *addr;
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	int err;
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	unsigned int retries = 0;
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	err = mutex_lock_interruptible(&u->readlock);
	if (err)
		return err;
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	err = 0;
	if (u->addr)
		goto out;

	err = -ENOMEM;
858
	addr = kzalloc(sizeof(*addr) + sizeof(short) + 16, GFP_KERNEL);
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	if (!addr)
		goto out;

	addr->name->sun_family = AF_UNIX;
	atomic_set(&addr->refcnt, 1);

retry:
	addr->len = sprintf(addr->name->sun_path+1, "%05x", ordernum) + 1 + sizeof(short);
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	addr->hash = unix_hash_fold(csum_partial(addr->name, addr->len, 0));
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	spin_lock(&unix_table_lock);
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	ordernum = (ordernum+1)&0xFFFFF;

872
	if (__unix_find_socket_byname(net, addr->name, addr->len, sock->type,
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				      addr->hash)) {
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		spin_unlock(&unix_table_lock);
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		/*
		 * __unix_find_socket_byname() may take long time if many names
		 * are already in use.
		 */
		cond_resched();
		/* Give up if all names seems to be in use. */
		if (retries++ == 0xFFFFF) {
			err = -ENOSPC;
			kfree(addr);
			goto out;
		}
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		goto retry;
	}
	addr->hash ^= sk->sk_type;

	__unix_remove_socket(sk);
	u->addr = addr;
	__unix_insert_socket(&unix_socket_table[addr->hash], sk);
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	spin_unlock(&unix_table_lock);
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	err = 0;

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out:	mutex_unlock(&u->readlock);
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	return err;
}

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static struct sock *unix_find_other(struct net *net,
				    struct sockaddr_un *sunname, int len,
902
				    int type, unsigned int hash, int *error)
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{
	struct sock *u;
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	struct path path;
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	int err = 0;
907

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	if (sunname->sun_path[0]) {
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		struct inode *inode;
		err = kern_path(sunname->sun_path, LOOKUP_FOLLOW, &path);
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		if (err)
			goto fail;
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		inode = d_backing_inode(path.dentry);
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		err = inode_permission(inode, MAY_WRITE);
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		if (err)
			goto put_fail;

		err = -ECONNREFUSED;
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		if (!S_ISSOCK(inode->i_mode))
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			goto put_fail;
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		u = unix_find_socket_byinode(inode);
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		if (!u)
			goto put_fail;

		if (u->sk_type == type)
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			touch_atime(&path);
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		path_put(&path);
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		err = -EPROTOTYPE;
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		if (u->sk_type != type) {
			sock_put(u);
			goto fail;
		}
	} else {
		err = -ECONNREFUSED;
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		u = unix_find_socket_byname(net, sunname, len, type, hash);
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		if (u) {
			struct dentry *dentry;
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			dentry = unix_sk(u)->path.dentry;
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			if (dentry)
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				touch_atime(&unix_sk(u)->path);
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		} else
			goto fail;
	}
	return u;

put_fail:
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	path_put(&path);
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fail:
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	*error = err;
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	return NULL;
}

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static int unix_mknod(struct dentry *dentry, struct path *path, umode_t mode,
		      struct path *res)
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{
958
	int err;
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960
	err = security_path_mknod(path, dentry, mode, 0);
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	if (!err) {
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		err = vfs_mknod(d_inode(path->dentry), dentry, mode, 0);
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		if (!err) {
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			res->mnt = mntget(path->mnt);
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			res->dentry = dget(dentry);
		}
	}
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	return err;
}
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static int unix_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
{
	struct sock *sk = sock->sk;
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	struct net *net = sock_net(sk);
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	struct unix_sock *u = unix_sk(sk);
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	struct sockaddr_un *sunaddr = (struct sockaddr_un *)uaddr;
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	char *sun_path = sunaddr->sun_path;
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	int err, name_err;
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	unsigned int hash;
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	struct unix_address *addr;
	struct hlist_head *list;
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	struct path path;
	struct dentry *dentry;
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	err = -EINVAL;
	if (sunaddr->sun_family != AF_UNIX)
		goto out;

990
	if (addr_len == sizeof(short)) {
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		err = unix_autobind(sock);
		goto out;
	}

	err = unix_mkname(sunaddr, addr_len, &hash);
	if (err < 0)
		goto out;
	addr_len = err;

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	name_err = 0;
	dentry = NULL;
	if (sun_path[0]) {
		/* Get the parent directory, calculate the hash for last
		 * component.
		 */
		dentry = kern_path_create(AT_FDCWD, sun_path, &path, 0);

		if (IS_ERR(dentry)) {
			/* delay report until after 'already bound' check */
			name_err = PTR_ERR(dentry);
			dentry = NULL;
		}
	}

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	err = mutex_lock_interruptible(&u->readlock);
	if (err)
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		goto out_path;
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	err = -EINVAL;
	if (u->addr)
		goto out_up;

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	if (name_err) {
		err = name_err == -EEXIST ? -EADDRINUSE : name_err;
		goto out_up;
	}

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	err = -ENOMEM;
	addr = kmalloc(sizeof(*addr)+addr_len, GFP_KERNEL);
	if (!addr)
		goto out_up;

	memcpy(addr->name, sunaddr, addr_len);
	addr->len = addr_len;
	addr->hash = hash ^ sk->sk_type;
	atomic_set(&addr->refcnt, 1);

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	if (dentry) {
		struct path u_path;
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		umode_t mode = S_IFSOCK |
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		       (SOCK_INODE(sock)->i_mode & ~current_umask());
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		err = unix_mknod(dentry, &path, mode, &u_path);
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		if (err) {
			if (err == -EEXIST)
				err = -EADDRINUSE;
			unix_release_addr(addr);
			goto out_up;
		}
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		addr->hash = UNIX_HASH_SIZE;
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		hash = d_backing_inode(dentry)->i_ino & (UNIX_HASH_SIZE - 1);
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		spin_lock(&unix_table_lock);
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		u->path = u_path;
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		list = &unix_socket_table[hash];
	} else {
		spin_lock(&unix_table_lock);
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		err = -EADDRINUSE;
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		if (__unix_find_socket_byname(net, sunaddr, addr_len,
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					      sk->sk_type, hash)) {
			unix_release_addr(addr);
			goto out_unlock;
		}

		list = &unix_socket_table[addr->hash];
	}

	err = 0;
	__unix_remove_socket(sk);
	u->addr = addr;
	__unix_insert_socket(list, sk);

out_unlock:
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	spin_unlock(&unix_table_lock);
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out_up:
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	mutex_unlock(&u->readlock);
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out_path:
	if (dentry)
		done_path_create(&path, dentry);

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out:
	return err;
}

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static void unix_state_double_lock(struct sock *sk1, struct sock *sk2)
{
	if (unlikely(sk1 == sk2) || !sk2) {
		unix_state_lock(sk1);
		return;
	}
	if (sk1 < sk2) {
		unix_state_lock(sk1);
		unix_state_lock_nested(sk2);
	} else {
		unix_state_lock(sk2);
		unix_state_lock_nested(sk1);
	}
}

static void unix_state_double_unlock(struct sock *sk1, struct sock *sk2)
{
	if (unlikely(sk1 == sk2) || !sk2) {
		unix_state_unlock(sk1);
		return;
	}
	unix_state_unlock(sk1);
	unix_state_unlock(sk2);
}

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static int unix_dgram_connect(struct socket *sock, struct sockaddr *addr,
			      int alen, int flags)
{
	struct sock *sk = sock->sk;
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	struct net *net = sock_net(sk);
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	struct sockaddr_un *sunaddr = (struct sockaddr_un *)addr;
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	struct sock *other;
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	unsigned int hash;
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	int err;

	if (addr->sa_family != AF_UNSPEC) {
		err = unix_mkname(sunaddr, alen, &hash);
		if (err < 0)
			goto out;
		alen = err;

		if (test_bit(SOCK_PASSCRED, &sock->flags) &&
		    !unix_sk(sk)->addr && (err = unix_autobind(sock)) != 0)
			goto out;

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restart:
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		other = unix_find_other(net, sunaddr, alen, sock->type, hash, &err);
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		if (!other)
			goto out;

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		unix_state_double_lock(sk, other);

		/* Apparently VFS overslept socket death. Retry. */
		if (sock_flag(other, SOCK_DEAD)) {
			unix_state_double_unlock(sk, other);
			sock_put(other);
			goto restart;
		}
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		err = -EPERM;
		if (!unix_may_send(sk, other))
			goto out_unlock;

		err = security_unix_may_send(sk->sk_socket, other->sk_socket);
		if (err)
			goto out_unlock;

	} else {
		/*
		 *	1003.1g breaking connected state with AF_UNSPEC
		 */
		other = NULL;
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		unix_state_double_lock(sk, other);
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	}

	/*
	 * If it was connected, reconnect.
	 */
	if (unix_peer(sk)) {
		struct sock *old_peer = unix_peer(sk);
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		unix_peer(sk) = other;
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		unix_dgram_peer_wake_disconnect_wakeup(sk, old_peer);

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		unix_state_double_unlock(sk, other);
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		if (other != old_peer)
			unix_dgram_disconnected(sk, old_peer);
		sock_put(old_peer);
	} else {
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		unix_peer(sk) = other;
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		unix_state_double_unlock(sk, other);
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	}
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	return 0;
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out_unlock:
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	unix_state_double_unlock(sk, other);
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	sock_put(other);
out:
	return err;
}

static long unix_wait_for_peer(struct sock *other, long timeo)
{
	struct unix_sock *u = unix_sk(other);
	int sched;
	DEFINE_WAIT(wait);

	prepare_to_wait_exclusive(&u->peer_wait, &wait, TASK_INTERRUPTIBLE);

	sched = !sock_flag(other, SOCK_DEAD) &&
		!(other->sk_shutdown & RCV_SHUTDOWN) &&
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		unix_recvq_full(other);
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	unix_state_unlock(other);
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	if (sched)
		timeo = schedule_timeout(timeo);

	finish_wait(&u->peer_wait, &wait);
	return timeo;
}

static int unix_stream_connect(struct socket *sock, struct sockaddr *uaddr,
			       int addr_len, int flags)
{
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	struct sockaddr_un *sunaddr = (struct sockaddr_un *)uaddr;
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	struct sock *sk = sock->sk;
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	struct net *net = sock_net(sk);
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	struct unix_sock *u = unix_sk(sk), *newu, *otheru;
	struct sock *newsk = NULL;
	struct sock *other = NULL;
	struct sk_buff *skb = NULL;
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	unsigned int hash;
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	int st;
	int err;
	long timeo;

	err = unix_mkname(sunaddr, addr_len, &hash);
	if (err < 0)
		goto out;
	addr_len = err;

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	if (test_bit(SOCK_PASSCRED, &sock->flags) && !u->addr &&
	    (err = unix_autobind(sock)) != 0)
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		goto out;

	timeo = sock_sndtimeo(sk, flags & O_NONBLOCK);

	/* First of all allocate resources.
	   If we will make it after state is locked,
	   we will have to recheck all again in any case.
	 */

	err = -ENOMEM;

	/* create new sock for complete connection */
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	newsk = unix_create1(sock_net(sk), NULL, 0);
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	if (newsk == NULL)
		goto out;

	/* Allocate skb for sending to listening sock */
	skb = sock_wmalloc(newsk, 1, 0, GFP_KERNEL);
	if (skb == NULL)
		goto out;

restart:
	/*  Find listening sock. */
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	other = unix_find_other(net, sunaddr, addr_len, sk->sk_type, hash, &err);
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	if (!other)
		goto out;

	/* Latch state of peer */
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	unix_state_lock(other);
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	/* Apparently VFS overslept socket death. Retry. */
	if (sock_flag(other, SOCK_DEAD)) {
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		unix_state_unlock(other);
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		sock_put(other);
		goto restart;
	}

	err = -ECONNREFUSED;
	if (other->sk_state != TCP_LISTEN)
		goto out_unlock;
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	if (other->sk_shutdown & RCV_SHUTDOWN)
		goto out_unlock;
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	if (unix_recvq_full(other)) {
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		err = -EAGAIN;
		if (!timeo)
			goto out_unlock;

		timeo = unix_wait_for_peer(other, timeo);

		err = sock_intr_errno(timeo);
		if (signal_pending(current))
			goto out;
		sock_put(other);
		goto restart;
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	}
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	/* Latch our state.

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	   It is tricky place. We need to grab our state lock and cannot
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	   drop lock on peer. It is dangerous because deadlock is
	   possible. Connect to self case and simultaneous
	   attempt to connect are eliminated by checking socket
	   state. other is TCP_LISTEN, if sk is TCP_LISTEN we
	   check this before attempt to grab lock.

	   Well, and we have to recheck the state after socket locked.
	 */
	st = sk->sk_state;

	switch (st) {
	case TCP_CLOSE:
		/* This is ok... continue with connect */
		break;
	case TCP_ESTABLISHED:
		/* Socket is already connected */
		err = -EISCONN;
		goto out_unlock;
	default:
		err = -EINVAL;
		goto out_unlock;
	}

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	unix_state_lock_nested(sk);
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	if (sk->sk_state != st) {
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		unix_state_unlock(sk);
		unix_state_unlock(other);
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		sock_put(other);
		goto restart;
	}

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	err = security_unix_stream_connect(sk, other, newsk);
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	if (err) {
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		unix_state_unlock(sk);
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		goto out_unlock;
	}

	/* The way is open! Fastly set all the necessary fields... */

	sock_hold(sk);
	unix_peer(newsk)	= sk;
	newsk->sk_state		= TCP_ESTABLISHED;
	newsk->sk_type		= sk->sk_type;
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	init_peercred(newsk);
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	newu = unix_sk(newsk);
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	RCU_INIT_POINTER(newsk->sk_wq, &newu->peer_wq);
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	otheru = unix_sk(other);

	/* copy address information from listening to new sock*/
	if (otheru->addr) {
		atomic_inc(&otheru->addr->refcnt);
		newu->addr = otheru->addr;
	}
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	if (otheru->path.dentry) {
		path_get(&otheru->path);
		newu->path = otheru->path;
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	}

	/* Set credentials */
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	copy_peercred(sk, other);
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	sock->state	= SS_CONNECTED;
	sk->sk_state	= TCP_ESTABLISHED;
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	sock_hold(newsk);

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	smp_mb__after_atomic();	/* sock_hold() does an atomic_inc() */
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	unix_peer(sk)	= newsk;
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	unix_state_unlock(sk);
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	/* take ten and and send info to listening sock */
	spin_lock(&other->sk_receive_queue.lock);
	__skb_queue_tail(&other->sk_receive_queue, skb);
	spin_unlock(&other->sk_receive_queue.lock);
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	unix_state_unlock(other);
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	other->sk_data_ready(other);
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	sock_put(other);
	return 0;

out_unlock:
	if (other)
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		unix_state_unlock(other);
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out:
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	kfree_skb(skb);
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	if (newsk)
		unix_release_sock(newsk, 0);
	if (other)
		sock_put(other);
	return err;
}

static int unix_socketpair(struct socket *socka, struct socket *sockb)
{
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	struct sock *ska = socka->sk, *skb = sockb->sk;
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	/* Join our sockets back to back */
	sock_hold(ska);
	sock_hold(skb);
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	unix_peer(ska) = skb;
	unix_peer(skb) = ska;
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	init_peercred(ska);
	init_peercred(skb);
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	if (ska->sk_type != SOCK_DGRAM) {
		ska->sk_state = TCP_ESTABLISHED;
		skb->sk_state = TCP_ESTABLISHED;
		socka->state  = SS_CONNECTED;
		sockb->state  = SS_CONNECTED;
	}
	return 0;
}

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static void unix_sock_inherit_flags(const struct socket *old,
				    struct socket *new)
{
	if (test_bit(SOCK_PASSCRED, &old->flags))
		set_bit(SOCK_PASSCRED, &new->flags);
	if (test_bit(SOCK_PASSSEC, &old->flags))
		set_bit(SOCK_PASSSEC, &new->flags);
}

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static int unix_accept(struct socket *sock, struct socket *newsock, int flags)
{
	struct sock *sk = sock->sk;
	struct sock *tsk;
	struct sk_buff *skb;
	int err;

	err = -EOPNOTSUPP;
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	if (sock->type != SOCK_STREAM && sock->type != SOCK_SEQPACKET)
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		goto out;

	err = -EINVAL;
	if (sk->sk_state != TCP_LISTEN)
		goto out;

	/* If socket state is TCP_LISTEN it cannot change (for now...),
	 * so that no locks are necessary.
	 */

	skb = skb_recv_datagram(sk, 0, flags&O_NONBLOCK, &err);
	if (!skb) {
		/* This means receive shutdown. */
		if (err == 0)
			err = -EINVAL;
		goto out;
	}

	tsk = skb->sk;
	skb_free_datagram(sk, skb);
	wake_up_interruptible(&unix_sk(sk)->peer_wait);

	/* attach accepted sock to socket */
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	unix_state_lock(tsk);
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	newsock->state = SS_CONNECTED;
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	unix_sock_inherit_flags(sock, newsock);
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	sock_graft(tsk, newsock);
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	unix_state_unlock(tsk);
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	return 0;

out:
	return err;
}


static int unix_getname(struct socket *sock, struct sockaddr *uaddr, int *uaddr_len, int peer)
{
	struct sock *sk = sock->sk;
	struct unix_sock *u;
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	DECLARE_SOCKADDR(struct sockaddr_un *, sunaddr, uaddr);
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	int err = 0;

	if (peer) {
		sk = unix_peer_get(sk);

		err = -ENOTCONN;
		if (!sk)
			goto out;
		err = 0;
	} else {
		sock_hold(sk);
	}

	u = unix_sk(sk);
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	unix_state_lock(sk);
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	if (!u->addr) {
		sunaddr->sun_family = AF_UNIX;
		sunaddr->sun_path[0] = 0;
		*uaddr_len = sizeof(short);
	} else {
		struct unix_address *addr = u->addr;

		*uaddr_len = addr->len;
		memcpy(sunaddr, addr->name, *uaddr_len);
	}
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	unix_state_unlock(sk);
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	sock_put(sk);
out:
	return err;
}

static void unix_detach_fds(struct scm_cookie *scm, struct sk_buff *skb)
{
	int i;

	scm->fp = UNIXCB(skb).fp;
	UNIXCB(skb).fp = NULL;

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	for (i = scm->fp->count-1; i >= 0; i--)
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		unix_notinflight(scm->fp->fp[i]);
}

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static void unix_destruct_scm(struct sk_buff *skb)
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{
	struct scm_cookie scm;
	memset(&scm, 0, sizeof(scm));
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	scm.pid  = UNIXCB(skb).pid;
	if (UNIXCB(skb).fp)
		unix_detach_fds(&scm, skb);
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	/* Alas, it calls VFS */
	/* So fscking what? fput() had been SMP-safe since the last Summer */
	scm_destroy(&scm);
	sock_wfree(skb);
}

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/*
 * The "user->unix_inflight" variable is protected by the garbage
 * collection lock, and we just read it locklessly here. If you go
 * over the limit, there might be a tiny race in actually noticing
 * it across threads. Tough.
 */
static inline bool too_many_unix_fds(struct task_struct *p)
{
	struct user_struct *user = current_user();

	if (unlikely(user->unix_inflight > task_rlimit(p, RLIMIT_NOFILE)))
		return !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN);
	return false;
}

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#define MAX_RECURSION_LEVEL 4

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static int unix_attach_fds(struct scm_cookie *scm, struct sk_buff *skb)
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{
	int i;
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	unsigned char max_level = 0;
	int unix_sock_count = 0;

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	if (too_many_unix_fds(current))
		return -ETOOMANYREFS;

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	for (i = scm->fp->count - 1; i >= 0; i--) {
		struct sock *sk = unix_get_socket(scm->fp->fp[i]);

		if (sk) {
			unix_sock_count++;
			max_level = max(max_level,
					unix_sk(sk)->recursion_level);
		}
	}
	if (unlikely(max_level > MAX_RECURSION_LEVEL))
		return -ETOOMANYREFS;
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	/*
	 * Need to duplicate file references for the sake of garbage
	 * collection.  Otherwise a socket in the fps might become a
	 * candidate for GC while the skb is not yet queued.
	 */
	UNIXCB(skb).fp = scm_fp_dup(scm->fp);
	if (!UNIXCB(skb).fp)
		return -ENOMEM;

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	for (i = scm->fp->count - 1; i >= 0; i--)
		unix_inflight(scm->fp->fp[i]);
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	return max_level;
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}

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static int unix_scm_to_skb(struct scm_cookie *scm, struct sk_buff *skb, bool send_fds)
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{
	int err = 0;
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	UNIXCB(skb).pid  = get_pid(scm->pid);
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	UNIXCB(skb).uid = scm->creds.uid;
	UNIXCB(skb).gid = scm->creds.gid;
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	UNIXCB(skb).fp = NULL;
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	unix_get_secdata(scm, skb);
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	if (scm->fp && send_fds)
		err = unix_attach_fds(scm, skb);

	skb->destructor = unix_destruct_scm;
	return err;
}

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static bool unix_passcred_enabled(const struct socket *sock,
				  const struct sock *other)
{
	return test_bit(SOCK_PASSCRED, &sock->flags) ||
	       !other->sk_socket ||
	       test_bit(SOCK_PASSCRED, &other->sk_socket->flags);
}

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/*
 * Some apps rely on write() giving SCM_CREDENTIALS
 * We include credentials if source or destination socket
 * asserted SOCK_PASSCRED.
 */
static void maybe_add_creds(struct sk_buff *skb, const struct socket *sock,
			    const struct sock *other)
{
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	if (UNIXCB(skb).pid)
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		return;
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	if (unix_passcred_enabled(sock, other)) {
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		UNIXCB(skb).pid  = get_pid(task_tgid(current));
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		current_uid_gid(&UNIXCB(skb).uid, &UNIXCB(skb).gid);
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	}
}

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static int maybe_init_creds(struct scm_cookie *scm,
			    struct socket *socket,
			    const struct sock *other)
{
	int err;
	struct msghdr msg = { .msg_controllen = 0 };

	err = scm_send(socket, &msg, scm, false);
	if (err)
		return err;

	if (unix_passcred_enabled(socket, other)) {
		scm->pid = get_pid(task_tgid(current));
		current_uid_gid(&scm->creds.uid, &scm->creds.gid);
	}
	return err;
}

static bool unix_skb_scm_eq(struct sk_buff *skb,
			    struct scm_cookie *scm)
{
	const struct unix_skb_parms *u = &UNIXCB(skb);

	return u->pid == scm->pid &&
	       uid_eq(u->uid, scm->creds.uid) &&
	       gid_eq(u->gid, scm->creds.gid) &&
	       unix_secdata_eq(scm, skb);
}

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/*
 *	Send AF_UNIX data.
 */

1640 1641
static int unix_dgram_sendmsg(struct socket *sock, struct msghdr *msg,
			      size_t len)
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{
	struct sock *sk = sock->sk;
1644
	struct net *net = sock_net(sk);
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	struct unix_sock *u = unix_sk(sk);
1646
	DECLARE_SOCKADDR(struct sockaddr_un *, sunaddr, msg->msg_name);
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	struct sock *other = NULL;
	int namelen = 0; /* fake GCC */
	int err;
1650
	unsigned int hash;
1651
	struct sk_buff *skb;
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	long timeo;
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	struct scm_cookie scm;
1654
	int max_level;
1655
	int data_len = 0;
1656
	int sk_locked;
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1658
	wait_for_unix_gc();
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	err = scm_send(sock, msg, &scm, false);
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	if (err < 0)
		return err;

	err = -EOPNOTSUPP;
	if (msg->msg_flags&MSG_OOB)
		goto out;

	if (msg->msg_namelen) {
		err = unix_mkname(sunaddr, msg->msg_namelen, &hash);
		if (err < 0)
			goto out;
		namelen = err;
	} else {
		sunaddr = NULL;
		err = -ENOTCONN;
		other = unix_peer_get(sk);
		if (!other)
			goto out;
	}

1680 1681
	if (test_bit(SOCK_PASSCRED, &sock->flags) && !u->addr
	    && (err = unix_autobind(sock)) != 0)
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		goto out;

	err = -EMSGSIZE;
	if (len > sk->sk_sndbuf - 32)
		goto out;

1688
	if (len > SKB_MAX_ALLOC) {
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		data_len = min_t(size_t,
				 len - SKB_MAX_ALLOC,
				 MAX_SKB_FRAGS * PAGE_SIZE);
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		data_len = PAGE_ALIGN(data_len);

		BUILD_BUG_ON(SKB_MAX_ALLOC < PAGE_SIZE);
	}
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	skb = sock_alloc_send_pskb(sk, len - data_len, data_len,
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				   msg->msg_flags & MSG_DONTWAIT, &err,
				   PAGE_ALLOC_COSTLY_ORDER);
1700
	if (skb == NULL)
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		goto out;

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	err = unix_scm_to_skb(&scm, skb, true);
1704
	if (err < 0)
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		goto out_free;
1706
	max_level = err + 1;
1707

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	skb_put(skb, len - data_len);
	skb->data_len = data_len;
	skb->len = len;
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	err = skb_copy_datagram_from_iter(skb, 0, &msg->msg_iter, len);
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	if (err)
		goto out_free;

	timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT);

restart:
	if (!other) {
		err = -ECONNRESET;
		if (sunaddr == NULL)
			goto out_free;

1723
		other = unix_find_other(net, sunaddr, namelen, sk->sk_type,
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					hash, &err);
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		if (other == NULL)
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			goto out_free;
	}

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	if (sk_filter(other, skb) < 0) {
		/* Toss the packet but do not return any error to the sender */
		err = len;
		goto out_free;
	}

1735
	sk_locked = 0;
1736
	unix_state_lock(other);
1737
restart_locked:
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	err = -EPERM;
	if (!unix_may_send(sk, other))
		goto out_unlock;

1742
	if (unlikely(sock_flag(other, SOCK_DEAD))) {
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		/*
		 *	Check with 1003.1g - what should
		 *	datagram error
		 */
1747
		unix_state_unlock(other);
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		sock_put(other);

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		if (!sk_locked)
			unix_state_lock(sk);

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		err = 0;
		if (unix_peer(sk) == other) {
1755
			unix_peer(sk) = NULL;
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			unix_dgram_peer_wake_disconnect_wakeup(sk, other);

1758
			unix_state_unlock(sk);
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			unix_dgram_disconnected(sk, other);
			sock_put(other);
			err = -ECONNREFUSED;
		} else {
1764
			unix_state_unlock(sk);
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		}

		other = NULL;
		if (err)
			goto out_free;
		goto restart;
	}

	err = -EPIPE;
	if (other->sk_shutdown & RCV_SHUTDOWN)
		goto out_unlock;

	if (sk->sk_type != SOCK_SEQPACKET) {
		err = security_unix_may_send(sk->sk_socket, other->sk_socket);
		if (err)
			goto out_unlock;
	}

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	if (unlikely(unix_peer(other) != sk && unix_recvq_full(other))) {
		if (timeo) {
			timeo = unix_wait_for_peer(other, timeo);

			err = sock_intr_errno(timeo);
			if (signal_pending(current))
				goto out_free;

			goto restart;
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		}

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		if (!sk_locked) {
			unix_state_unlock(other);
			unix_state_double_lock(sk, other);
		}
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		if (unix_peer(sk) != other ||
		    unix_dgram_peer_wake_me(sk, other)) {
			err = -EAGAIN;
			sk_locked = 1;
			goto out_unlock;
		}
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		if (!sk_locked) {
			sk_locked = 1;
			goto restart_locked;
		}
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	}

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	if (unlikely(sk_locked))
		unix_state_unlock(sk);

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	if (sock_flag(other, SOCK_RCVTSTAMP))
		__net_timestamp(skb);
1817
	maybe_add_creds(skb, sock, other);
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	skb_queue_tail(&other->sk_receive_queue, skb);
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	if (max_level > unix_sk(other)->recursion_level)
		unix_sk(other)->recursion_level = max_level;
1821
	unix_state_unlock(other);
1822
	other->sk_data_ready(other);
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	sock_put(other);
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	scm_destroy(&scm);
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	return len;

out_unlock:
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	if (sk_locked)
		unix_state_unlock(sk);
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	unix_state_unlock(other);
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out_free:
	kfree_skb(skb);
out:
	if (other)
		sock_put(other);
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	scm_destroy(&scm);
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	return err;
}

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/* We use paged skbs for stream sockets, and limit occupancy to 32768
 * bytes, and a minimun of a full page.
 */
#define UNIX_SKB_FRAGS_SZ (PAGE_SIZE << get_order(32768))
1844

1845 1846
static int unix_stream_sendmsg(struct socket *sock, struct msghdr *msg,
			       size_t len)
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{
	struct sock *sk = sock->sk;
	struct sock *other = NULL;
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	int err, size;
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	struct sk_buff *skb;
1852
	int sent = 0;
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	struct scm_cookie scm;
1854
	bool fds_sent = false;
1855
	int max_level;
1856
	int data_len;
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1858
	wait_for_unix_gc();
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	err = scm_send(sock, msg, &scm, false);
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	if (err < 0)
		return err;

	err = -EOPNOTSUPP;
	if (msg->msg_flags&MSG_OOB)
		goto out_err;

	if (msg->msg_namelen) {
		err = sk->sk_state == TCP_ESTABLISHED ? -EISCONN : -EOPNOTSUPP;
		goto out_err;
	} else {
		err = -ENOTCONN;
1872
		other = unix_peer(sk);
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		if (!other)
			goto out_err;
	}

	if (sk->sk_shutdown & SEND_SHUTDOWN)
		goto pipe_err;

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	while (sent < len) {
1881
		size = len - sent;
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		/* Keep two messages in the pipe so it schedules better */
1884
		size = min_t(int, size, (sk->sk_sndbuf >> 1) - 64);
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1886 1887
		/* allow fallback to order-0 allocations */
		size = min_t(int, size, SKB_MAX_HEAD(0) + UNIX_SKB_FRAGS_SZ);
1888

1889
		data_len = max_t(int, 0, size - SKB_MAX_HEAD(0));
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1891 1892
		data_len = min_t(size_t, size, PAGE_ALIGN(data_len));

1893
		skb = sock_alloc_send_pskb(sk, size - data_len, data_len,
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					   msg->msg_flags & MSG_DONTWAIT, &err,
					   get_order(UNIX_SKB_FRAGS_SZ));
1896
		if (!skb)
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			goto out_err;

1899
		/* Only send the fds in the first buffer */
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		err = unix_scm_to_skb(&scm, skb, !fds_sent);
1901
		if (err < 0) {
1902
			kfree_skb(skb);
1903
			goto out_err;
1904
		}
1905
		max_level = err + 1;
1906
		fds_sent = true;
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1908 1909 1910
		skb_put(skb, size - data_len);
		skb->data_len = data_len;
		skb->len = size;
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		err = skb_copy_datagram_from_iter(skb, 0, &msg->msg_iter, size);
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		if (err) {
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			kfree_skb(skb);
1914
			goto out_err;
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		}

1917
		unix_state_lock(other);
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		if (sock_flag(other, SOCK_DEAD) ||
		    (other->sk_shutdown & RCV_SHUTDOWN))
			goto pipe_err_free;

1923
		maybe_add_creds(skb, sock, other);
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		skb_queue_tail(&other->sk_receive_queue, skb);
1925 1926
		if (max_level > unix_sk(other)->recursion_level)
			unix_sk(other)->recursion_level = max_level;
1927
		unix_state_unlock(other);
1928
		other->sk_data_ready(other);
1929
		sent += size;
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	}

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	scm_destroy(&scm);
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	return sent;

pipe_err_free:
1937
	unix_state_unlock(other);
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	kfree_skb(skb);
pipe_err:
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	if (sent == 0 && !(msg->msg_flags&MSG_NOSIGNAL))
		send_sig(SIGPIPE, current, 0);
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	err = -EPIPE;
out_err:
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	scm_destroy(&scm);
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	return sent ? : err;
}

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static ssize_t unix_stream_sendpage(struct socket *socket, struct page *page,
				    int offset, size_t size, int flags)
{
1951 1952 1953 1954
	int err;
	bool send_sigpipe = false;
	bool init_scm = true;
	struct scm_cookie scm;
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	struct sock *other, *sk = socket->sk;
	struct sk_buff *skb, *newskb = NULL, *tail = NULL;

	if (flags & MSG_OOB)
		return -EOPNOTSUPP;

	other = unix_peer(sk);
	if (!other || sk->sk_state != TCP_ESTABLISHED)
		return -ENOTCONN;

	if (false) {
alloc_skb:
		unix_state_unlock(other);
		mutex_unlock(&unix_sk(other)->readlock);
		newskb = sock_alloc_send_pskb(sk, 0, 0, flags & MSG_DONTWAIT,
					      &err, 0);
		if (!newskb)
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			goto err;
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	}

	/* we must acquire readlock as we modify already present
	 * skbs in the sk_receive_queue and mess with skb->len
	 */
	err = mutex_lock_interruptible(&unix_sk(other)->readlock);
	if (err) {
		err = flags & MSG_DONTWAIT ? -EAGAIN : -ERESTARTSYS;
		goto err;
	}

	if (sk->sk_shutdown & SEND_SHUTDOWN) {
		err = -EPIPE;
1986
		send_sigpipe = true;
1987 1988 1989 1990 1991 1992 1993 1994
		goto err_unlock;
	}

	unix_state_lock(other);

	if (sock_flag(other, SOCK_DEAD) ||
	    other->sk_shutdown & RCV_SHUTDOWN) {
		err = -EPIPE;
1995
		send_sigpipe = true;
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		goto err_state_unlock;
	}

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	if (init_scm) {
		err = maybe_init_creds(&scm, socket, other);
		if (err)
			goto err_state_unlock;
		init_scm = false;
	}

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	skb = skb_peek_tail(&other->sk_receive_queue);
	if (tail && tail == skb) {
		skb = newskb;
2009 2010
	} else if (!skb || !unix_skb_scm_eq(skb, &scm)) {
		if (newskb) {
2011
			skb = newskb;
2012 2013
		} else {
			tail = skb;
2014
			goto alloc_skb;
2015
		}
2016 2017 2018 2019 2020 2021
	} else if (newskb) {
		/* this is fast path, we don't necessarily need to
		 * call to kfree_skb even though with newskb == NULL
		 * this - does no harm
		 */
		consume_skb(newskb);
2022
		newskb = NULL;
2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034
	}

	if (skb_append_pagefrags(skb, page, offset, size)) {
		tail = skb;
		goto alloc_skb;
	}

	skb->len += size;
	skb->data_len += size;
	skb->truesize += size;
	atomic_add(size, &sk->sk_wmem_alloc);

2035
	if (newskb) {
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		err = unix_scm_to_skb(&scm, skb, false);
		if (err)
			goto err_state_unlock;
2039
		spin_lock(&other->sk_receive_queue.lock);
2040
		__skb_queue_tail(&other->sk_receive_queue, newskb);
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		spin_unlock(&other->sk_receive_queue.lock);
	}
2043 2044 2045 2046 2047

	unix_state_unlock(other);
	mutex_unlock(&unix_sk(other)->readlock);

	other->sk_data_ready(other);
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	scm_destroy(&scm);
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	return size;

err_state_unlock:
	unix_state_unlock(other);
err_unlock:
	mutex_unlock(&unix_sk(other)->readlock);
err:
	kfree_skb(newskb);
	if (send_sigpipe && !(flags & MSG_NOSIGNAL))
		send_sig(SIGPIPE, current, 0);
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	if (!init_scm)
		scm_destroy(&scm);
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	return err;
}

2064 2065
static int unix_seqpacket_sendmsg(struct socket *sock, struct msghdr *msg,
				  size_t len)
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{
	int err;
	struct sock *sk = sock->sk;
2069

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	err = sock_error(sk);
	if (err)
		return err;

	if (sk->sk_state != TCP_ESTABLISHED)
		return -ENOTCONN;

	if (msg->msg_namelen)
		msg->msg_namelen = 0;

2080
	return unix_dgram_sendmsg(sock, msg, len);
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}
2082

2083 2084
static int unix_seqpacket_recvmsg(struct socket *sock, struct msghdr *msg,
				  size_t size, int flags)
2085 2086 2087 2088 2089 2090
{
	struct sock *sk = sock->sk;

	if (sk->sk_state != TCP_ESTABLISHED)
		return -ENOTCONN;

2091
	return unix_dgram_recvmsg(sock, msg, size, flags);
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}

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static void unix_copy_addr(struct msghdr *msg, struct sock *sk)
{
	struct unix_sock *u = unix_sk(sk);

	if (u->addr) {
		msg->msg_namelen = u->addr->len;
		memcpy(msg->msg_name, u->addr->name, u->addr->len);
	}
}

2104 2105
static int unix_dgram_recvmsg(struct socket *sock, struct msghdr *msg,
			      size_t size, int flags)
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{
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	struct scm_cookie scm;
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	struct sock *sk = sock->sk;
	struct unix_sock *u = unix_sk(sk);
	int noblock = flags & MSG_DONTWAIT;
	struct sk_buff *skb;
	int err;
2113
	int peeked, skip;
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	err = -EOPNOTSUPP;
	if (flags&MSG_OOB)
		goto out;

2119
	err = mutex_lock_interruptible(&u->readlock);
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	if (unlikely(err)) {
		/* recvmsg() in non blocking mode is supposed to return -EAGAIN
		 * sk_rcvtimeo is not honored by mutex_lock_interruptible()
		 */
		err = noblock ? -EAGAIN : -ERESTARTSYS;
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		goto out;
	}
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	skip = sk_peek_offset(sk, flags);

	skb = __skb_recv_datagram(sk, flags, &peeked, &skip, &err);
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	if (!skb) {
		unix_state_lock(sk);
		/* Signal EOF on disconnected non-blocking SEQPACKET socket. */
		if (sk->sk_type == SOCK_SEQPACKET && err == -EAGAIN &&
		    (sk->sk_shutdown & RCV_SHUTDOWN))
			err = 0;
		unix_state_unlock(sk);
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		goto out_unlock;
2139
	}
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	wake_up_interruptible_sync_poll(&u->peer_wait,
					POLLOUT | POLLWRNORM | POLLWRBAND);
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	if (msg->msg_name)
		unix_copy_addr(msg, skb->sk);

2147 2148 2149
	if (size > skb->len - skip)
		size = skb->len - skip;
	else if (size < skb->len - skip)
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		msg->msg_flags |= MSG_TRUNC;

2152
	err = skb_copy_datagram_msg(skb, skip, msg, size);
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	if (err)
		goto out_free;

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	if (sock_flag(sk, SOCK_RCVTSTAMP))
		__sock_recv_timestamp(msg, sk, skb);

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	memset(&scm, 0, sizeof(scm));

	scm_set_cred(&scm, UNIXCB(skb).pid, UNIXCB(skb).uid, UNIXCB(skb).gid);
	unix_set_secdata(&scm, skb);
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	if (!(flags & MSG_PEEK)) {
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		if (UNIXCB(skb).fp)
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			unix_detach_fds(&scm, skb);
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		sk_peek_offset_bwd(sk, skb->len);
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	} else {
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		/* It is questionable: on PEEK we could:
		   - do not return fds - good, but too simple 8)
		   - return fds, and do not return them on read (old strategy,
		     apparently wrong)
		   - clone fds (I chose it for now, it is the most universal
		     solution)
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		   POSIX 1003.1g does not actually define this clearly
		   at all. POSIX 1003.1g doesn't define a lot of things
		   clearly however!

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		*/
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		sk_peek_offset_fwd(sk, size);

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		if (UNIXCB(skb).fp)
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			scm.fp = scm_fp_dup(UNIXCB(skb).fp);
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	}
2188
	err = (flags & MSG_TRUNC) ? skb->len - skip : size;
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	scm_recv(sock, msg, &scm, flags);
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out_free:
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	skb_free_datagram(sk, skb);
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out_unlock:
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	mutex_unlock(&u->readlock);
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out:
	return err;
}

/*
2201
 *	Sleep until more data has arrived. But check for races..
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 */
2203
static long unix_stream_data_wait(struct sock *sk, long timeo,
2204
				  struct sk_buff *last, unsigned int last_len)
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{
2206
	struct sk_buff *tail;
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	DEFINE_WAIT(wait);

2209
	unix_state_lock(sk);
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	for (;;) {
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		prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
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		tail = skb_peek_tail(&sk->sk_receive_queue);
		if (tail != last ||
		    (tail && tail->len != last_len) ||
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		    sk->sk_err ||
		    (sk->sk_shutdown & RCV_SHUTDOWN) ||
		    signal_pending(current) ||
		    !timeo)
			break;

		set_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags);
2224
		unix_state_unlock(sk);
2225
		timeo = freezable_schedule_timeout(timeo);
2226
		unix_state_lock(sk);
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		if (sock_flag(sk, SOCK_DEAD))
			break;

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		clear_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags);
	}

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	finish_wait(sk_sleep(sk), &wait);
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	unix_state_unlock(sk);
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	return timeo;
}

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static unsigned int unix_skb_len(const struct sk_buff *skb)
{
	return skb->len - UNIXCB(skb).consumed;
}

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struct unix_stream_read_state {
	int (*recv_actor)(struct sk_buff *, int, int,
			  struct unix_stream_read_state *);
	struct socket *socket;
	struct msghdr *msg;
	struct pipe_inode_info *pipe;
	size_t size;
	int flags;
	unsigned int splice_flags;
};

static int unix_stream_read_generic(struct unix_stream_read_state *state)
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{
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	struct scm_cookie scm;
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	struct socket *sock = state->socket;
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	struct sock *sk = sock->sk;
	struct unix_sock *u = unix_sk(sk);
	int copied = 0;
2262
	int flags = state->flags;
2263
	int noblock = flags & MSG_DONTWAIT;
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	bool check_creds = false;
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	int target;
	int err = 0;
	long timeo;
2268
	int skip;
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	size_t size = state->size;
	unsigned int last_len;
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	err = -EINVAL;
	if (sk->sk_state != TCP_ESTABLISHED)
		goto out;

	err = -EOPNOTSUPP;
2277
	if (flags & MSG_OOB)
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		goto out;

2280
	target = sock_rcvlowat(sk, flags & MSG_WAITALL, size);
2281
	timeo = sock_rcvtimeo(sk, noblock);
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	memset(&scm, 0, sizeof(scm));

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	/* Lock the socket to prevent queue disordering
	 * while sleeps in memcpy_tomsg
	 */
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	mutex_lock(&u->readlock);
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	if (flags & MSG_PEEK)
		skip = sk_peek_offset(sk, flags);
	else
		skip = 0;

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	do {
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		int chunk;
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		bool drop_skb;
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		struct sk_buff *skb, *last;
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2300
		unix_state_lock(sk);
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		if (sock_flag(sk, SOCK_DEAD)) {
			err = -ECONNRESET;
			goto unlock;
		}
2305
		last = skb = skb_peek(&sk->sk_receive_queue);
2306
		last_len = last ? last->len : 0;
2307
again:
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		if (skb == NULL) {
2309
			unix_sk(sk)->recursion_level = 0;
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			if (copied >= target)
2311
				goto unlock;
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			/*
			 *	POSIX 1003.1g mandates this order.
			 */
2316

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			err = sock_error(sk);
			if (err)
2319
				goto unlock;
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			if (sk->sk_shutdown & RCV_SHUTDOWN)
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				goto unlock;

			unix_state_unlock(sk);
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			err = -EAGAIN;
			if (!timeo)
				break;
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			mutex_unlock(&u->readlock);
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2329 2330
			timeo = unix_stream_data_wait(sk, timeo, last,
						      last_len);
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2332
			if (signal_pending(current)) {
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				err = sock_intr_errno(timeo);
				goto out;
			}
2336

2337
			mutex_lock(&u->readlock);
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			continue;
2339
unlock:
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			unix_state_unlock(sk);
			break;
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		}
2343

2344 2345
		while (skip >= unix_skb_len(skb)) {
			skip -= unix_skb_len(skb);
2346
			last = skb;
2347
			last_len = skb->len;
2348
			skb = skb_peek_next(skb, &sk->sk_receive_queue);
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			if (!skb)
				goto again;
2351 2352
		}

2353
		unix_state_unlock(sk);
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		if (check_creds) {
			/* Never glue messages from different writers */
2357
			if (!unix_skb_scm_eq(skb, &scm))
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				break;
2359
		} else if (test_bit(SOCK_PASSCRED, &sock->flags)) {
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			/* Copy credentials */
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			scm_set_cred(&scm, UNIXCB(skb).pid, UNIXCB(skb).uid, UNIXCB(skb).gid);
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			unix_set_secdata(&scm, skb);
2363
			check_creds = true;
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		}

		/* Copy address just once */
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		if (state->msg && state->msg->msg_name) {
			DECLARE_SOCKADDR(struct sockaddr_un *, sunaddr,
					 state->msg->msg_name);
			unix_copy_addr(state->msg, skb->sk);
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			sunaddr = NULL;
		}

2374
		chunk = min_t(unsigned int, unix_skb_len(skb) - skip, size);
2375
		skb_get(skb);
2376
		chunk = state->recv_actor(skb, skip, chunk, state);
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		drop_skb = !unix_skb_len(skb);
		/* skb is only safe to use if !drop_skb */
		consume_skb(skb);
2380
		if (chunk < 0) {
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			if (copied == 0)
				copied = -EFAULT;
			break;
		}
		copied += chunk;
		size -= chunk;

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		if (drop_skb) {
			/* the skb was touched by a concurrent reader;
			 * we should not expect anything from this skb
			 * anymore and assume it invalid - we can be
			 * sure it was dropped from the socket queue
			 *
			 * let's report a short read
			 */
			err = 0;
			break;
		}

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		/* Mark read part of skb as used */
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		if (!(flags & MSG_PEEK)) {
2402
			UNIXCB(skb).consumed += chunk;
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2404 2405
			sk_peek_offset_bwd(sk, chunk);

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			if (UNIXCB(skb).fp)
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				unix_detach_fds(&scm, skb);
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2409
			if (unix_skb_len(skb))
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				break;

2412
			skb_unlink(skb, &sk->sk_receive_queue);
2413
			consume_skb(skb);
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			if (scm.fp)
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				break;
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		} else {
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			/* It is questionable, see note in unix_dgram_recvmsg.
			 */
			if (UNIXCB(skb).fp)
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				scm.fp = scm_fp_dup(UNIXCB(skb).fp);
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2423
			sk_peek_offset_fwd(sk, chunk);
2424

2425 2426 2427
			if (UNIXCB(skb).fp)
				break;

2428
			skip = 0;
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			last = skb;
			last_len = skb->len;
			unix_state_lock(sk);
			skb = skb_peek_next(skb, &sk->sk_receive_queue);
			if (skb)
				goto again;
			unix_state_unlock(sk);
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			break;
		}
	} while (size);

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	mutex_unlock(&u->readlock);
2441 2442 2443 2444
	if (state->msg)
		scm_recv(sock, state->msg, &scm, flags);
	else
		scm_destroy(&scm);
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out:
	return copied ? : err;
}

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static int unix_stream_read_actor(struct sk_buff *skb,
				  int skip, int chunk,
				  struct unix_stream_read_state *state)
{
	int ret;

	ret = skb_copy_datagram_msg(skb, UNIXCB(skb).consumed + skip,
				    state->msg, chunk);
	return ret ?: chunk;
}

static int unix_stream_recvmsg(struct socket *sock, struct msghdr *msg,
			       size_t size, int flags)
{
	struct unix_stream_read_state state = {
		.recv_actor = unix_stream_read_actor,
		.socket = sock,
		.msg = msg,
		.size = size,
		.flags = flags
	};

	return unix_stream_read_generic(&state);
}

static ssize_t skb_unix_socket_splice(struct sock *sk,
				      struct pipe_inode_info *pipe,
				      struct splice_pipe_desc *spd)
{
	int ret;
	struct unix_sock *u = unix_sk(sk);

	mutex_unlock(&u->readlock);
	ret = splice_to_pipe(pipe, spd);
	mutex_lock(&u->readlock);

	return ret;
}

static int unix_stream_splice_actor(struct sk_buff *skb,
				    int skip, int chunk,
				    struct unix_stream_read_state *state)
{
	return skb_splice_bits(skb, state->socket->sk,
			       UNIXCB(skb).consumed + skip,
			       state->pipe, chunk, state->splice_flags,
			       skb_unix_socket_splice);
}

static ssize_t unix_stream_splice_read(struct socket *sock,  loff_t *ppos,
				       struct pipe_inode_info *pipe,
				       size_t size, unsigned int flags)
{
	struct unix_stream_read_state state = {
		.recv_actor = unix_stream_splice_actor,
		.socket = sock,
		.pipe = pipe,
		.size = size,
		.splice_flags = flags,
	};

	if (unlikely(*ppos))
		return -ESPIPE;

	if (sock->file->f_flags & O_NONBLOCK ||
	    flags & SPLICE_F_NONBLOCK)
		state.flags = MSG_DONTWAIT;

	return unix_stream_read_generic(&state);
}

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static int unix_shutdown(struct socket *sock, int mode)
{
	struct sock *sk = sock->sk;
	struct sock *other;

2525 2526 2527 2528 2529 2530 2531 2532
	if (mode < SHUT_RD || mode > SHUT_RDWR)
		return -EINVAL;
	/* This maps:
	 * SHUT_RD   (0) -> RCV_SHUTDOWN  (1)
	 * SHUT_WR   (1) -> SEND_SHUTDOWN (2)
	 * SHUT_RDWR (2) -> SHUTDOWN_MASK (3)
	 */
	++mode;
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	unix_state_lock(sk);
	sk->sk_shutdown |= mode;
	other = unix_peer(sk);
	if (other)
		sock_hold(other);
	unix_state_unlock(sk);
	sk->sk_state_change(sk);

	if (other &&
		(sk->sk_type == SOCK_STREAM || sk->sk_type == SOCK_SEQPACKET)) {

		int peer_mode = 0;

		if (mode&RCV_SHUTDOWN)
			peer_mode |= SEND_SHUTDOWN;
		if (mode&SEND_SHUTDOWN)
			peer_mode |= RCV_SHUTDOWN;
		unix_state_lock(other);
		other->sk_shutdown |= peer_mode;
		unix_state_unlock(other);
		other->sk_state_change(other);
		if (peer_mode == SHUTDOWN_MASK)
			sk_wake_async(other, SOCK_WAKE_WAITD, POLL_HUP);
		else if (peer_mode & RCV_SHUTDOWN)
			sk_wake_async(other, SOCK_WAKE_WAITD, POLL_IN);
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	}
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	if (other)
		sock_put(other);

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	return 0;
}

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long unix_inq_len(struct sock *sk)
{
	struct sk_buff *skb;
	long amount = 0;

	if (sk->sk_state == TCP_LISTEN)
		return -EINVAL;

	spin_lock(&sk->sk_receive_queue.lock);
	if (sk->sk_type == SOCK_STREAM ||
	    sk->sk_type == SOCK_SEQPACKET) {
		skb_queue_walk(&sk->sk_receive_queue, skb)
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			amount += unix_skb_len(skb);
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	} else {
		skb = skb_peek(&sk->sk_receive_queue);
		if (skb)
			amount = skb->len;
	}
	spin_unlock(&sk->sk_receive_queue.lock);

	return amount;
}
EXPORT_SYMBOL_GPL(unix_inq_len);

long unix_outq_len(struct sock *sk)
{
	return sk_wmem_alloc_get(sk);
}
EXPORT_SYMBOL_GPL(unix_outq_len);

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static int unix_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
{
	struct sock *sk = sock->sk;
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	long amount = 0;
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	int err;

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	switch (cmd) {
	case SIOCOUTQ:
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		amount = unix_outq_len(sk);
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		err = put_user(amount, (int __user *)arg);
		break;
	case SIOCINQ:
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		amount = unix_inq_len(sk);
		if (amount < 0)
			err = amount;
		else
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			err = put_user(amount, (int __user *)arg);
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		break;
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	default:
		err = -ENOIOCTLCMD;
		break;
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	}
	return err;
}

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static unsigned int unix_poll(struct file *file, struct socket *sock, poll_table *wait)
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{
	struct sock *sk = sock->sk;
	unsigned int mask;

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	sock_poll_wait(file, sk_sleep(sk), wait);
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	mask = 0;

	/* exceptional events? */
	if (sk->sk_err)
		mask |= POLLERR;
	if (sk->sk_shutdown == SHUTDOWN_MASK)
		mask |= POLLHUP;
2634
	if (sk->sk_shutdown & RCV_SHUTDOWN)
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		mask |= POLLRDHUP | POLLIN | POLLRDNORM;
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	/* readable? */
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	if (!skb_queue_empty(&sk->sk_receive_queue))
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		mask |= POLLIN | POLLRDNORM;

	/* Connection-based need to check for termination and startup */
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	if ((sk->sk_type == SOCK_STREAM || sk->sk_type == SOCK_SEQPACKET) &&
	    sk->sk_state == TCP_CLOSE)
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		mask |= POLLHUP;

	/*
	 * we set writable also when the other side has shut down the
	 * connection. This prevents stuck sockets.
	 */
	if (unix_writable(sk))
		mask |= POLLOUT | POLLWRNORM | POLLWRBAND;

	return mask;
}

2656 2657
static unsigned int unix_dgram_poll(struct file *file, struct socket *sock,
				    poll_table *wait)
2658
{
2659 2660
	struct sock *sk = sock->sk, *other;
	unsigned int mask, writable;
2661

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	sock_poll_wait(file, sk_sleep(sk), wait);
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	mask = 0;

	/* exceptional events? */
	if (sk->sk_err || !skb_queue_empty(&sk->sk_error_queue))
2667
		mask |= POLLERR |
2668
			(sock_flag(sk, SOCK_SELECT_ERR_QUEUE) ? POLLPRI : 0);
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	if (sk->sk_shutdown & RCV_SHUTDOWN)
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		mask |= POLLRDHUP | POLLIN | POLLRDNORM;
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	if (sk->sk_shutdown == SHUTDOWN_MASK)
		mask |= POLLHUP;

	/* readable? */
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	if (!skb_queue_empty(&sk->sk_receive_queue))
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		mask |= POLLIN | POLLRDNORM;

	/* Connection-based need to check for termination and startup */
	if (sk->sk_type == SOCK_SEQPACKET) {
		if (sk->sk_state == TCP_CLOSE)
			mask |= POLLHUP;
		/* connection hasn't started yet? */
		if (sk->sk_state == TCP_SYN_SENT)
			return mask;
	}

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	/* No write status requested, avoid expensive OUT tests. */
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	if (!(poll_requested_events(wait) & (POLLWRBAND|POLLWRNORM|POLLOUT)))
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		return mask;

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	writable = unix_writable(sk);
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	if (writable) {
		unix_state_lock(sk);

		other = unix_peer(sk);
		if (other && unix_peer(other) != sk &&
		    unix_recvq_full(other) &&
		    unix_dgram_peer_wake_me(sk, other))
			writable = 0;

		unix_state_unlock(sk);
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	}

	if (writable)
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		mask |= POLLOUT | POLLWRNORM | POLLWRBAND;
	else
		set_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);

	return mask;
}
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#ifdef CONFIG_PROC_FS
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#define BUCKET_SPACE (BITS_PER_LONG - (UNIX_HASH_BITS + 1) - 1)

#define get_bucket(x) ((x) >> BUCKET_SPACE)
#define get_offset(x) ((x) & ((1L << BUCKET_SPACE) - 1))
#define set_bucket_offset(b, o) ((b) << BUCKET_SPACE | (o))
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static struct sock *unix_from_bucket(struct seq_file *seq, loff_t *pos)
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{
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	unsigned long offset = get_offset(*pos);
	unsigned long bucket = get_bucket(*pos);
	struct sock *sk;
	unsigned long count = 0;
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	for (sk = sk_head(&unix_socket_table[bucket]); sk; sk = sk_next(sk)) {
		if (sock_net(sk) != seq_file_net(seq))
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			continue;
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		if (++count == offset)
			break;
	}

	return sk;
}

static struct sock *unix_next_socket(struct seq_file *seq,
				     struct sock *sk,
				     loff_t *pos)
{
	unsigned long bucket;

	while (sk > (struct sock *)SEQ_START_TOKEN) {
		sk = sk_next(sk);
		if (!sk)
			goto next_bucket;
		if (sock_net(sk) == seq_file_net(seq))
			return sk;
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	}
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	do {
		sk = unix_from_bucket(seq, pos);
		if (sk)
			return sk;

next_bucket:
		bucket = get_bucket(*pos) + 1;
		*pos = set_bucket_offset(bucket, 1);
	} while (bucket < ARRAY_SIZE(unix_socket_table));

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	return NULL;
}

static void *unix_seq_start(struct seq_file *seq, loff_t *pos)
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	__acquires(unix_table_lock)
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{
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	spin_lock(&unix_table_lock);
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	if (!*pos)
		return SEQ_START_TOKEN;

	if (get_bucket(*pos) >= ARRAY_SIZE(unix_socket_table))
		return NULL;

	return unix_next_socket(seq, NULL, pos);
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}

static void *unix_seq_next(struct seq_file *seq, void *v, loff_t *pos)
{
	++*pos;
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	return unix_next_socket(seq, v, pos);
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}

static void unix_seq_stop(struct seq_file *seq, void *v)
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	__releases(unix_table_lock)
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{
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	spin_unlock(&unix_table_lock);
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}

static int unix_seq_show(struct seq_file *seq, void *v)
{
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	if (v == SEQ_START_TOKEN)
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		seq_puts(seq, "Num       RefCount Protocol Flags    Type St "
			 "Inode Path\n");
	else {
		struct sock *s = v;
		struct unix_sock *u = unix_sk(s);
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		unix_state_lock(s);
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		seq_printf(seq, "%pK: %08X %08X %08X %04X %02X %5lu",
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			s,
			atomic_read(&s->sk_refcnt),
			0,
			s->sk_state == TCP_LISTEN ? __SO_ACCEPTCON : 0,
			s->sk_type,
			s->sk_socket ?
			(s->sk_state == TCP_ESTABLISHED ? SS_CONNECTED : SS_UNCONNECTED) :
			(s->sk_state == TCP_ESTABLISHED ? SS_CONNECTING : SS_DISCONNECTING),
			sock_i_ino(s));

		if (u->addr) {
			int i, len;
			seq_putc(seq, ' ');

			i = 0;
			len = u->addr->len - sizeof(short);
			if (!UNIX_ABSTRACT(s))
				len--;
			else {
				seq_putc(seq, '@');
				i++;
			}
			for ( ; i < len; i++)
				seq_putc(seq, u->addr->name->sun_path[i]);
		}
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		unix_state_unlock(s);
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		seq_putc(seq, '\n');
	}

	return 0;
}

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static const struct seq_operations unix_seq_ops = {
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	.start  = unix_seq_start,
	.next   = unix_seq_next,
	.stop   = unix_seq_stop,
	.show   = unix_seq_show,
};

static int unix_seq_open(struct inode *inode, struct file *file)
{
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	return seq_open_net(inode, file, &unix_seq_ops,
2845
			    sizeof(struct seq_net_private));
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}

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static const struct file_operations unix_seq_fops = {
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	.owner		= THIS_MODULE,
	.open		= unix_seq_open,
	.read		= seq_read,
	.llseek		= seq_lseek,
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	.release	= seq_release_net,
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};

#endif

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static const struct net_proto_family unix_family_ops = {
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	.family = PF_UNIX,
	.create = unix_create,
	.owner	= THIS_MODULE,
};

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static int __net_init unix_net_init(struct net *net)
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{
	int error = -ENOMEM;

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	net->unx.sysctl_max_dgram_qlen = 10;
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	if (unix_sysctl_register(net))
		goto out;
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#ifdef CONFIG_PROC_FS
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	if (!proc_create("unix", 0, net->proc_net, &unix_seq_fops)) {
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		unix_sysctl_unregister(net);
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		goto out;
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	}
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#endif
	error = 0;
out:
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	return error;
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}

2884
static void __net_exit unix_net_exit(struct net *net)
2885
{
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	unix_sysctl_unregister(net);
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	remove_proc_entry("unix", net->proc_net);
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}

static struct pernet_operations unix_net_ops = {
	.init = unix_net_init,
	.exit = unix_net_exit,
};

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static int __init af_unix_init(void)
{
	int rc = -1;

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	BUILD_BUG_ON(sizeof(struct unix_skb_parms) > FIELD_SIZEOF(struct sk_buff, cb));
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	rc = proto_register(&unix_proto, 1);
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	if (rc != 0) {
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		pr_crit("%s: Cannot create unix_sock SLAB cache!\n", __func__);
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		goto out;
	}

	sock_register(&unix_family_ops);
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	register_pernet_subsys(&unix_net_ops);
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out:
	return rc;
}

static void __exit af_unix_exit(void)
{
	sock_unregister(PF_UNIX);
	proto_unregister(&unix_proto);
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	unregister_pernet_subsys(&unix_net_ops);
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}

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/* Earlier than device_initcall() so that other drivers invoking
   request_module() don't end up in a loop when modprobe tries
   to use a UNIX socket. But later than subsys_initcall() because
   we depend on stuff initialised there */
fs_initcall(af_unix_init);
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module_exit(af_unix_exit);

MODULE_LICENSE("GPL");
MODULE_ALIAS_NETPROTO(PF_UNIX);