/*
   * NET4:	Implementation of BSD Unix domain sockets.
   *

   * Authors:	Alan Cox, <alan@lxorguk.ukuu.org.uk>

   *
   *		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.
   */

  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

  #include <linux/module.h>

  #include <linux/kernel.h>

  #include <linux/signal.h>

  #include <linux/sched/signal.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 <linux/uaccess.h>

  #include <linux/skbuff.h>
  #include <linux/netdevice.h>

  #include <net/net_namespace.h>

  #include <net/sock.h>

  #include <net/tcp_states.h>

  #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>

  #include <linux/freezer.h>

  #include <linux/file.h>

  struct hlist_head unix_socket_table[2 * UNIX_HASH_SIZE];

  EXPORT_SYMBOL_GPL(unix_socket_table);
  DEFINE_SPINLOCK(unix_table_lock);
  EXPORT_SYMBOL_GPL(unix_table_lock);

  static atomic_long_t unix_nr_socks;

  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)

  #ifdef CONFIG_SECURITY_NETWORK

  static void unix_get_secdata(struct scm_cookie *scm, struct sk_buff *skb)

  {

  	UNIXCB(skb).secid = scm->secid;

  }
  
  static inline void unix_set_secdata(struct scm_cookie *scm, struct sk_buff *skb)
  {

  	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);

  }
  #else

  static inline void unix_get_secdata(struct scm_cookie *scm, struct sk_buff *skb)

  { }
  
  static inline void unix_set_secdata(struct scm_cookie *scm, struct sk_buff *skb)
  { }

  
  static inline bool unix_secdata_eq(struct scm_cookie *scm, struct sk_buff *skb)
  {
  	return true;
  }

  #endif /* CONFIG_SECURITY_NETWORK */

  /*
   *  SMP locking strategy:

   *    hash table is protected with spinlock unix_table_lock

   *    each socket state is protected by separate spin lock.

   */

  static inline unsigned int unix_hash_fold(__wsum n)

  {

  	unsigned int hash = (__force unsigned int)csum_fold(n);

  	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)
  {

  	return unix_peer(osk) == NULL || unix_our_peer(sk, osk);

  }

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

  struct sock *unix_peer_get(struct sock *s)

  {
  	struct sock *peer;

  	unix_state_lock(s);

  	peer = unix_peer(s);
  	if (peer)
  		sock_hold(peer);

  	unix_state_unlock(s);

  	return peer;
  }

  EXPORT_SYMBOL_GPL(unix_peer_get);

  
  static inline void unix_release_addr(struct unix_address *addr)
  {

  	if (refcount_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.
   */

  static int unix_mkname(struct sockaddr_un *sunaddr, int len, unsigned int *hashp)

  {
  	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.

  		 * sun_path[108] doesn't as such exist.  However in kernel space

  		 * we are guaranteed that it is a valid memory location in our
  		 * kernel address buffer.
  		 */

  		((char *)sunaddr)[len] = 0;

  		len = strlen(sunaddr->sun_path)+1+sizeof(short);
  		return len;
  	}

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

  	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)
  {

  	WARN_ON(!sk_unhashed(sk));

  	sk_add_node(sk, list);
  }
  
  static inline void unix_remove_socket(struct sock *sk)
  {

  	spin_lock(&unix_table_lock);

  	__unix_remove_socket(sk);

  	spin_unlock(&unix_table_lock);

  }
  
  static inline void unix_insert_socket(struct hlist_head *list, struct sock *sk)
  {

  	spin_lock(&unix_table_lock);

  	__unix_insert_socket(list, sk);

  	spin_unlock(&unix_table_lock);

  }

  static struct sock *__unix_find_socket_byname(struct net *net,
  					      struct sockaddr_un *sunname,

  					      int len, int type, unsigned int hash)

  {
  	struct sock *s;

  	sk_for_each(s, &unix_socket_table[hash ^ type]) {

  		struct unix_sock *u = unix_sk(s);

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

  			continue;

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

  static inline struct sock *unix_find_socket_byname(struct net *net,
  						   struct sockaddr_un *sunname,

  						   int len, int type,

  						   unsigned int hash)

  {
  	struct sock *s;

  	spin_lock(&unix_table_lock);

  	s = __unix_find_socket_byname(net, sunname, len, type, hash);

  	if (s)
  		sock_hold(s);

  	spin_unlock(&unix_table_lock);

  	return s;
  }

  static struct sock *unix_find_socket_byinode(struct inode *i)

  {
  	struct sock *s;

  	spin_lock(&unix_table_lock);

  	sk_for_each(s,

  		    &unix_socket_table[i->i_ino & (UNIX_HASH_SIZE - 1)]) {

  		struct dentry *dentry = unix_sk(s)->path.dentry;

  		if (dentry && d_backing_inode(dentry) == i) {

  			sock_hold(s);
  			goto found;
  		}
  	}
  	s = NULL;
  found:

  	spin_unlock(&unix_table_lock);

  	return s;
  }

  /* 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_entry_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_entry_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;
  }

  static int unix_writable(const struct sock *sk)

  {

  	return sk->sk_state != TCP_LISTEN &&

  	       (refcount_read(&sk->sk_wmem_alloc) << 2) <= sk->sk_sndbuf;

  }
  
  static void unix_write_space(struct sock *sk)
  {

  	struct socket_wq *wq;
  
  	rcu_read_lock();

  	if (unix_writable(sk)) {

  		wq = rcu_dereference(sk->sk_wq);

  		if (skwq_has_sleeper(wq))

  			wake_up_interruptible_sync_poll(&wq->wait,
  				POLLOUT | POLLWRNORM | POLLWRBAND);

  		sk_wake_async(sk, SOCK_WAKE_SPACE, POLL_OUT);

  	}

  	rcu_read_unlock();

  }
  
  /* 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)
  {

  	if (!skb_queue_empty(&sk->sk_receive_queue)) {

  		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);

  	WARN_ON(refcount_read(&sk->sk_wmem_alloc));

  	WARN_ON(!sk_unhashed(sk));
  	WARN_ON(sk->sk_socket);

  	if (!sock_flag(sk, SOCK_DEAD)) {

  		pr_info("Attempt to release alive unix socket: %p
  ", sk);

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

  	atomic_long_dec(&unix_nr_socks);

  	local_bh_disable();

  	sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);

  	local_bh_enable();

  #ifdef UNIX_REFCNT_DEBUG

  	pr_debug("UNIX %p is destroyed, %ld are still alive.
  ", sk,

  		atomic_long_read(&unix_nr_socks));

  #endif
  }

  static void unix_release_sock(struct sock *sk, int embrion)

  {
  	struct unix_sock *u = unix_sk(sk);

  	struct path path;

  	struct sock *skpair;
  	struct sk_buff *skb;
  	int state;
  
  	unix_remove_socket(sk);
  
  	/* Clear state */

  	unix_state_lock(sk);

  	sock_orphan(sk);
  	sk->sk_shutdown = SHUTDOWN_MASK;

  	path	     = u->path;
  	u->path.dentry = NULL;
  	u->path.mnt = NULL;

  	state = sk->sk_state;
  	sk->sk_state = TCP_CLOSE;

  	unix_state_unlock(sk);

  
  	wake_up_interruptible_all(&u->peer_wait);

  	skpair = unix_peer(sk);

  	if (skpair != NULL) {

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

  			unix_state_lock(skpair);

  			/* No more writes */
  			skpair->sk_shutdown = SHUTDOWN_MASK;
  			if (!skb_queue_empty(&sk->sk_receive_queue) || embrion)
  				skpair->sk_err = ECONNRESET;

  			unix_state_unlock(skpair);

  			skpair->sk_state_change(skpair);

  			sk_wake_async(skpair, SOCK_WAKE_WAITD, POLL_HUP);

  		}

  
  		unix_dgram_peer_wake_disconnect(sk, skpair);

  		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) {

  		if (state == TCP_LISTEN)

  			unix_release_sock(skb->sk, 1);
  		/* passed fds are erased in the kfree_skb hook	      */

  		UNIXCB(skb).consumed = skb->len;

  		kfree_skb(skb);
  	}

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

  
  	sock_put(sk);
  
  	/* ---- Socket is dead now and most probably destroyed ---- */
  
  	/*

  	 * Fixme: BSD difference: In BSD all sockets connected to us get

  	 *	  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)
  	 */

  	if (unix_tot_inflight)

  		unix_gc();		/* Garbage collect fds */

  }

  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);
  }

  static int unix_listen(struct socket *sock, int backlog)
  {
  	int err;
  	struct sock *sk = sock->sk;
  	struct unix_sock *u = unix_sk(sk);

  	struct pid *old_pid = NULL;

  
  	err = -EOPNOTSUPP;

  	if (sock->type != SOCK_STREAM && sock->type != SOCK_SEQPACKET)
  		goto out;	/* Only stream/seqpacket sockets accept */

  	err = -EINVAL;
  	if (!u->addr)

  		goto out;	/* No listens on an unbound socket */

  	unix_state_lock(sk);

  	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 */

  	init_peercred(sk);

  	err = 0;
  
  out_unlock:

  	unix_state_unlock(sk);

  	put_pid(old_pid);

  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, bool);

  static int unix_getname(struct socket *, struct sockaddr *, int *, int);
  static unsigned int unix_poll(struct file *, struct socket *, poll_table *);

  static unsigned int unix_dgram_poll(struct file *, struct socket *,
  				    poll_table *);

  static int unix_ioctl(struct socket *, unsigned int, unsigned long);
  static int unix_shutdown(struct socket *, int);

  static int unix_stream_sendmsg(struct socket *, struct msghdr *, size_t);
  static int unix_stream_recvmsg(struct socket *, struct msghdr *, size_t, int);

  static ssize_t unix_stream_sendpage(struct socket *, struct page *, int offset,
  				    size_t size, int flags);

  static ssize_t unix_stream_splice_read(struct socket *,  loff_t *ppos,
  				       struct pipe_inode_info *, size_t size,
  				       unsigned int flags);

  static int unix_dgram_sendmsg(struct socket *, struct msghdr *, size_t);
  static int unix_dgram_recvmsg(struct socket *, struct msghdr *, size_t, int);

  static int unix_dgram_connect(struct socket *, struct sockaddr *,
  			      int, int);

  static int unix_seqpacket_sendmsg(struct socket *, struct msghdr *, size_t);
  static int unix_seqpacket_recvmsg(struct socket *, struct msghdr *, size_t,
  				  int);

  static int unix_set_peek_off(struct sock *sk, int val)

  {
  	struct unix_sock *u = unix_sk(sk);

  	if (mutex_lock_interruptible(&u->iolock))

  		return -EINTR;

  	sk->sk_peek_off = val;

  	mutex_unlock(&u->iolock);

  
  	return 0;

  }

  static const struct proto_ops unix_stream_ops = {

  	.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,

  	.sendpage =	unix_stream_sendpage,

  	.splice_read =	unix_stream_splice_read,

  	.set_peek_off =	unix_set_peek_off,

  };

  static const struct proto_ops unix_dgram_ops = {

  	.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,

  	.poll =		unix_dgram_poll,

  	.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,

  	.set_peek_off =	unix_set_peek_off,

  };

  static const struct proto_ops unix_seqpacket_ops = {

  	.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_dgram_poll,

  	.ioctl =	unix_ioctl,
  	.listen =	unix_listen,
  	.shutdown =	unix_shutdown,
  	.setsockopt =	sock_no_setsockopt,
  	.getsockopt =	sock_no_getsockopt,
  	.sendmsg =	unix_seqpacket_sendmsg,

  	.recvmsg =	unix_seqpacket_recvmsg,

  	.mmap =		sock_no_mmap,
  	.sendpage =	sock_no_sendpage,

  	.set_peek_off =	unix_set_peek_off,

  };
  
  static struct proto unix_proto = {

  	.name			= "UNIX",
  	.owner			= THIS_MODULE,

  	.obj_size		= sizeof(struct unix_sock),

  };

  /*
   * 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;

  static struct sock *unix_create1(struct net *net, struct socket *sock, int kern)

  {
  	struct sock *sk = NULL;
  	struct unix_sock *u;

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

  		goto out;

  	sk = sk_alloc(net, PF_UNIX, GFP_KERNEL, &unix_proto, kern);

  	if (!sk)
  		goto out;

  	sock_init_data(sock, sk);

  	lockdep_set_class(&sk->sk_receive_queue.lock,
  				&af_unix_sk_receive_queue_lock_key);

  	sk->sk_allocation	= GFP_KERNEL_ACCOUNT;

  	sk->sk_write_space	= unix_write_space;

  	sk->sk_max_ack_backlog	= net->unx.sysctl_max_dgram_qlen;

  	sk->sk_destruct		= unix_sock_destructor;
  	u	  = unix_sk(sk);

  	u->path.dentry = NULL;
  	u->path.mnt = NULL;

  	spin_lock_init(&u->lock);

  	atomic_long_set(&u->inflight, 0);

  	INIT_LIST_HEAD(&u->link);

  	mutex_init(&u->iolock); /* single task reading lock */
  	mutex_init(&u->bindlock); /* single task binding lock */

  	init_waitqueue_head(&u->peer_wait);

  	init_waitqueue_func_entry(&u->peer_wake, unix_dgram_peer_wake_relay);

  	unix_insert_socket(unix_sockets_unbound(sk), sk);

  out:

  	if (sk == NULL)

  		atomic_long_dec(&unix_nr_socks);

  	else {
  		local_bh_disable();

  		sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);

  		local_bh_enable();
  	}

  	return sk;
  }

  static int unix_create(struct net *net, struct socket *sock, int protocol,
  		       int kern)

  {
  	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:

  		sock->type = SOCK_DGRAM;

  	case SOCK_DGRAM:
  		sock->ops = &unix_dgram_ops;
  		break;
  	case SOCK_SEQPACKET:
  		sock->ops = &unix_seqpacket_ops;
  		break;
  	default:
  		return -ESOCKTNOSUPPORT;
  	}

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

  }
  
  static int unix_release(struct socket *sock)
  {
  	struct sock *sk = sock->sk;
  
  	if (!sk)
  		return 0;

  	unix_release_sock(sk, 0);

  	sock->sk = NULL;

  	return 0;

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

  	struct net *net = sock_net(sk);

  	struct unix_sock *u = unix_sk(sk);
  	static u32 ordernum = 1;

  	struct unix_address *addr;

  	int err;

  	unsigned int retries = 0;

  	err = mutex_lock_interruptible(&u->bindlock);

  	if (err)
  		return err;

  
  	err = 0;
  	if (u->addr)
  		goto out;
  
  	err = -ENOMEM;

  	addr = kzalloc(sizeof(*addr) + sizeof(short) + 16, GFP_KERNEL);

  	if (!addr)
  		goto out;

  	addr->name->sun_family = AF_UNIX;

  	refcount_set(&addr->refcnt, 1);

  
  retry:
  	addr->len = sprintf(addr->name->sun_path+1, "%05x", ordernum) + 1 + sizeof(short);

  	addr->hash = unix_hash_fold(csum_partial(addr->name, addr->len, 0));

  	spin_lock(&unix_table_lock);

  	ordernum = (ordernum+1)&0xFFFFF;

  	if (__unix_find_socket_byname(net, addr->name, addr->len, sock->type,

  				      addr->hash)) {

  		spin_unlock(&unix_table_lock);

  		/*
  		 * __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;
  		}

  		goto retry;
  	}
  	addr->hash ^= sk->sk_type;
  
  	__unix_remove_socket(sk);
  	u->addr = addr;
  	__unix_insert_socket(&unix_socket_table[addr->hash], sk);

  	spin_unlock(&unix_table_lock);

  	err = 0;

  out:	mutex_unlock(&u->bindlock);

  	return err;
  }

  static struct sock *unix_find_other(struct net *net,
  				    struct sockaddr_un *sunname, int len,

  				    int type, unsigned int hash, int *error)

  {
  	struct sock *u;

  	struct path path;

  	int err = 0;

  	if (sunname->sun_path[0]) {

  		struct inode *inode;
  		err = kern_path(sunname->sun_path, LOOKUP_FOLLOW, &path);

  		if (err)
  			goto fail;

  		inode = d_backing_inode(path.dentry);

  		err = inode_permission(inode, MAY_WRITE);

  		if (err)
  			goto put_fail;
  
  		err = -ECONNREFUSED;

  		if (!S_ISSOCK(inode->i_mode))

  			goto put_fail;

  		u = unix_find_socket_byinode(inode);

  		if (!u)
  			goto put_fail;
  
  		if (u->sk_type == type)

  			touch_atime(&path);

  		path_put(&path);

  		err = -EPROTOTYPE;

  		if (u->sk_type != type) {
  			sock_put(u);
  			goto fail;
  		}
  	} else {
  		err = -ECONNREFUSED;

  		u = unix_find_socket_byname(net, sunname, len, type, hash);

  		if (u) {
  			struct dentry *dentry;

  			dentry = unix_sk(u)->path.dentry;

  			if (dentry)

  				touch_atime(&unix_sk(u)->path);

  		} else
  			goto fail;
  	}
  	return u;
  
  put_fail:

  	path_put(&path);

  fail:

  	*error = err;

  	return NULL;
  }

  static int unix_mknod(const char *sun_path, umode_t mode, struct path *res)

  {

  	struct dentry *dentry;
  	struct path path;
  	int err = 0;
  	/*
  	 * Get the parent directory, calculate the hash for last
  	 * component.
  	 */
  	dentry = kern_path_create(AT_FDCWD, sun_path, &path, 0);
  	err = PTR_ERR(dentry);
  	if (IS_ERR(dentry))
  		return err;

  	/*
  	 * All right, let's create it.
  	 */
  	err = security_path_mknod(&path, dentry, mode, 0);

  	if (!err) {

  		err = vfs_mknod(d_inode(path.dentry), dentry, mode, 0);

  		if (!err) {

  			res->mnt = mntget(path.mnt);

  			res->dentry = dget(dentry);
  		}
  	}

  	done_path_create(&path, dentry);

  	return err;
  }

  
  static int unix_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
  {
  	struct sock *sk = sock->sk;

  	struct net *net = sock_net(sk);

  	struct unix_sock *u = unix_sk(sk);

  	struct sockaddr_un *sunaddr = (struct sockaddr_un *)uaddr;

  	char *sun_path = sunaddr->sun_path;

  	int err;

  	unsigned int hash;

  	struct unix_address *addr;
  	struct hlist_head *list;

  	struct path path = { };

  
  	err = -EINVAL;

  	if (addr_len < offsetofend(struct sockaddr_un, sun_family) ||
  	    sunaddr->sun_family != AF_UNIX)

  		goto out;

  	if (addr_len == sizeof(short)) {

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

  	if (sun_path[0]) {
  		umode_t mode = S_IFSOCK |
  		       (SOCK_INODE(sock)->i_mode & ~current_umask());
  		err = unix_mknod(sun_path, mode, &path);
  		if (err) {
  			if (err == -EEXIST)
  				err = -EADDRINUSE;
  			goto out;
  		}
  	}

  	err = mutex_lock_interruptible(&u->bindlock);

  	if (err)

  		goto out_put;

  
  	err = -EINVAL;
  	if (u->addr)
  		goto out_up;
  
  	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;

  	refcount_set(&addr->refcnt, 1);

  	if (sun_path[0]) {

  		addr->hash = UNIX_HASH_SIZE;

  		hash = d_backing_inode(path.dentry)->i_ino & (UNIX_HASH_SIZE - 1);

  		spin_lock(&unix_table_lock);

  		u->path = path;

  		list = &unix_socket_table[hash];
  	} else {
  		spin_lock(&unix_table_lock);

  		err = -EADDRINUSE;

  		if (__unix_find_socket_byname(net, sunaddr, addr_len,

  					      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:

  	spin_unlock(&unix_table_lock);

  out_up:

  	mutex_unlock(&u->bindlock);

  out_put:
  	if (err)
  		path_put(&path);

  out:
  	return err;

  }

  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);
  }

  static int unix_dgram_connect(struct socket *sock, struct sockaddr *addr,
  			      int alen, int flags)
  {
  	struct sock *sk = sock->sk;

  	struct net *net = sock_net(sk);

  	struct sockaddr_un *sunaddr = (struct sockaddr_un *)addr;

  	struct sock *other;

  	unsigned int hash;

  	int err;

  	err = -EINVAL;
  	if (alen < offsetofend(struct sockaddr, sa_family))
  		goto out;

  	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;

  restart:

  		other = unix_find_other(net, sunaddr, alen, sock->type, hash, &err);

  		if (!other)
  			goto out;

  		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;
  		}

  
  		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;

  		unix_state_double_lock(sk, other);

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

  		unix_peer(sk) = other;

  		unix_dgram_peer_wake_disconnect_wakeup(sk, old_peer);

  		unix_state_double_unlock(sk, other);

  
  		if (other != old_peer)
  			unix_dgram_disconnected(sk, old_peer);
  		sock_put(old_peer);
  	} else {

  		unix_peer(sk) = other;

  		unix_state_double_unlock(sk, other);

  	}

  	return 0;

  
  out_unlock:

  	unix_state_double_unlock(sk, other);

  	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) &&

  		unix_recvq_full(other);

  	unix_state_unlock(other);

  
  	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)
  {

  	struct sockaddr_un *sunaddr = (struct sockaddr_un *)uaddr;

  	struct sock *sk = sock->sk;

  	struct net *net = sock_net(sk);

  	struct unix_sock *u = unix_sk(sk), *newu, *otheru;
  	struct sock *newsk = NULL;
  	struct sock *other = NULL;
  	struct sk_buff *skb = NULL;

  	unsigned int hash;

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

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

  		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 */

  	newsk = unix_create1(sock_net(sk), NULL, 0);

  	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. */

  	other = unix_find_other(net, sunaddr, addr_len, sk->sk_type, hash, &err);

  	if (!other)
  		goto out;
  
  	/* Latch state of peer */

  	unix_state_lock(other);

  
  	/* Apparently VFS overslept socket death. Retry. */
  	if (sock_flag(other, SOCK_DEAD)) {

  		unix_state_unlock(other);

  		sock_put(other);
  		goto restart;
  	}
  
  	err = -ECONNREFUSED;
  	if (other->sk_state != TCP_LISTEN)
  		goto out_unlock;

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

  	if (unix_recvq_full(other)) {

  		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;

  	}

  
  	/* Latch our state.

  	   It is tricky place. We need to grab our state lock and cannot

  	   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;
  	}

  	unix_state_lock_nested(sk);

  
  	if (sk->sk_state != st) {

  		unix_state_unlock(sk);
  		unix_state_unlock(other);

  		sock_put(other);
  		goto restart;
  	}

  	err = security_unix_stream_connect(sk, other, newsk);

  	if (err) {

  		unix_state_unlock(sk);

  		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;

  	init_peercred(newsk);

  	newu = unix_sk(newsk);

  	RCU_INIT_POINTER(newsk->sk_wq, &newu->peer_wq);

  	otheru = unix_sk(other);
  
  	/* copy address information from listening to new sock*/
  	if (otheru->addr) {

  		refcount_inc(&otheru->addr->refcnt);

  		newu->addr = otheru->addr;
  	}

  	if (otheru->path.dentry) {
  		path_get(&otheru->path);
  		newu->path = otheru->path;

  	}
  
  	/* Set credentials */

  	copy_peercred(sk, other);

  	sock->state	= SS_CONNECTED;
  	sk->sk_state	= TCP_ESTABLISHED;

  	sock_hold(newsk);

  	smp_mb__after_atomic();	/* sock_hold() does an atomic_inc() */

  	unix_peer(sk)	= newsk;

  	unix_state_unlock(sk);

  
  	/* 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);

  	unix_state_unlock(other);

  	other->sk_data_ready(other);

  	sock_put(other);
  	return 0;
  
  out_unlock:
  	if (other)

  		unix_state_unlock(other);

  
  out:

  	kfree_skb(skb);

  	if (newsk)
  		unix_release_sock(newsk, 0);
  	if (other)
  		sock_put(other);
  	return err;
  }
  
  static int unix_socketpair(struct socket *socka, struct socket *sockb)
  {

  	struct sock *ska = socka->sk, *skb = sockb->sk;

  
  	/* Join our sockets back to back */
  	sock_hold(ska);
  	sock_hold(skb);

  	unix_peer(ska) = skb;
  	unix_peer(skb) = ska;

  	init_peercred(ska);
  	init_peercred(skb);

  
  	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;
  }

  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);
  }

  static int unix_accept(struct socket *sock, struct socket *newsock, int flags,
  		       bool kern)

  {
  	struct sock *sk = sock->sk;
  	struct sock *tsk;
  	struct sk_buff *skb;
  	int err;
  
  	err = -EOPNOTSUPP;

  	if (sock->type != SOCK_STREAM && sock->type != SOCK_SEQPACKET)

  		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 */

  	unix_state_lock(tsk);

  	newsock->state = SS_CONNECTED;

  	unix_sock_inherit_flags(sock, newsock);

  	sock_graft(tsk, newsock);

  	unix_state_unlock(tsk);

  	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;

  	DECLARE_SOCKADDR(struct sockaddr_un *, sunaddr, uaddr);

  	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);

  	unix_state_lock(sk);

  	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);
  	}

  	unix_state_unlock(sk);

  	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;

  	for (i = scm->fp->count-1; i >= 0; i--)

  		unix_notinflight(scm->fp->user, scm->fp->fp[i]);

  }

  static void unix_destruct_scm(struct sk_buff *skb)

  {
  	struct scm_cookie scm;
  	memset(&scm, 0, sizeof(scm));

  	scm.pid  = UNIXCB(skb).pid;

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

  
  	/* Alas, it calls VFS */
  	/* So fscking what? fput() had been SMP-safe since the last Summer */
  	scm_destroy(&scm);
  	sock_wfree(skb);
  }

  /*
   * 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;
  }

  static int unix_attach_fds(struct scm_cookie *scm, struct sk_buff *skb)

  {
  	int i;

  	if (too_many_unix_fds(current))
  		return -ETOOMANYREFS;

  	/*
  	 * 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;

  	for (i = scm->fp->count - 1; i >= 0; i--)

  		unix_inflight(scm->fp->user, scm->fp->fp[i]);

  	return 0;

  }

  static int unix_scm_to_skb(struct scm_cookie *scm, struct sk_buff *skb, bool send_fds)

  {
  	int err = 0;

  	UNIXCB(skb).pid  = get_pid(scm->pid);

  	UNIXCB(skb).uid = scm->creds.uid;
  	UNIXCB(skb).gid = scm->creds.gid;

  	UNIXCB(skb).fp = NULL;

  	unix_get_secdata(scm, skb);

  	if (scm->fp && send_fds)
  		err = unix_attach_fds(scm, skb);
  
  	skb->destructor = unix_destruct_scm;
  	return err;
  }

  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);
  }

  /*

   * 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)
  {

  	if (UNIXCB(skb).pid)

  		return;

  	if (unix_passcred_enabled(sock, other)) {

  		UNIXCB(skb).pid  = get_pid(task_tgid(current));

  		current_uid_gid(&UNIXCB(skb).uid, &UNIXCB(skb).gid);

  	}
  }

  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);
  }

  /*

   *	Send AF_UNIX data.
   */

  static int unix_dgram_sendmsg(struct socket *sock, struct msghdr *msg,
  			      size_t len)

  {

  	struct sock *sk = sock->sk;

  	struct net *net = sock_net(sk);

  	struct unix_sock *u = unix_sk(sk);

  	DECLARE_SOCKADDR(struct sockaddr_un *, sunaddr, msg->msg_name);

  	struct sock *other = NULL;
  	int namelen = 0; /* fake GCC */
  	int err;

  	unsigned int hash;

  	struct sk_buff *skb;

  	long timeo;

  	struct scm_cookie scm;

  	int data_len = 0;

  	int sk_locked;

  	wait_for_unix_gc();

  	err = scm_send(sock, msg, &scm, false);

  	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;
  	}

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

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

  	if (len > SKB_MAX_ALLOC) {

  		data_len = min_t(size_t,
  				 len - SKB_MAX_ALLOC,
  				 MAX_SKB_FRAGS * PAGE_SIZE);

  		data_len = PAGE_ALIGN(data_len);
  
  		BUILD_BUG_ON(SKB_MAX_ALLOC < PAGE_SIZE);
  	}

  
  	skb = sock_alloc_send_pskb(sk, len - data_len, data_len,

  				   msg->msg_flags & MSG_DONTWAIT, &err,
  				   PAGE_ALLOC_COSTLY_ORDER);

  	if (skb == NULL)

  		goto out;

  	err = unix_scm_to_skb(&scm, skb, true);

  	if (err < 0)

  		goto out_free;

  	skb_put(skb, len - data_len);
  	skb->data_len = data_len;
  	skb->len = len;

  	err = skb_copy_datagram_from_iter(skb, 0, &msg->msg_iter, len);

  	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;

  		other = unix_find_other(net, sunaddr, namelen, sk->sk_type,

  					hash, &err);

  		if (other == NULL)

  			goto out_free;
  	}

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

  	sk_locked = 0;

  	unix_state_lock(other);

  restart_locked:

  	err = -EPERM;
  	if (!unix_may_send(sk, other))
  		goto out_unlock;

  	if (unlikely(sock_flag(other, SOCK_DEAD))) {

  		/*
  		 *	Check with 1003.1g - what should
  		 *	datagram error
  		 */

  		unix_state_unlock(other);

  		sock_put(other);

  		if (!sk_locked)
  			unix_state_lock(sk);

  		err = 0;

  		if (unix_peer(sk) == other) {

  			unix_peer(sk) = NULL;

  			unix_dgram_peer_wake_disconnect_wakeup(sk, other);

  			unix_state_unlock(sk);

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

  			unix_state_unlock(sk);

  		}
  
  		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;
  	}

  	/* other == sk && unix_peer(other) != sk if
  	 * - unix_peer(sk) == NULL, destination address bound to sk
  	 * - unix_peer(sk) == sk by time of get but disconnected before lock
  	 */
  	if (other != sk &&
  	    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;

  		}

  		if (!sk_locked) {
  			unix_state_unlock(other);
  			unix_state_double_lock(sk, other);
  		}

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

  		if (!sk_locked) {
  			sk_locked = 1;
  			goto restart_locked;
  		}

  	}

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

  	if (sock_flag(other, SOCK_RCVTSTAMP))
  		__net_timestamp(skb);

  	maybe_add_creds(skb, sock, other);

  	skb_queue_tail(&other->sk_receive_queue, skb);

  	unix_state_unlock(other);

  	other->sk_data_ready(other);

  	sock_put(other);

  	scm_destroy(&scm);

  	return len;
  
  out_unlock:

  	if (sk_locked)
  		unix_state_unlock(sk);

  	unix_state_unlock(other);

  out_free:
  	kfree_skb(skb);
  out:
  	if (other)
  		sock_put(other);

  	scm_destroy(&scm);

  	return err;
  }

  /* 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))

  static int unix_stream_sendmsg(struct socket *sock, struct msghdr *msg,
  			       size_t len)

  {

  	struct sock *sk = sock->sk;
  	struct sock *other = NULL;

  	int err, size;

  	struct sk_buff *skb;

  	int sent = 0;

  	struct scm_cookie scm;

  	bool fds_sent = false;

  	int data_len;

  	wait_for_unix_gc();

  	err = scm_send(sock, msg, &scm, false);

  	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;

  		other = unix_peer(sk);

  		if (!other)
  			goto out_err;
  	}
  
  	if (sk->sk_shutdown & SEND_SHUTDOWN)
  		goto pipe_err;

  	while (sent < len) {

  		size = len - sent;

  
  		/* Keep two messages in the pipe so it schedules better */

  		size = min_t(int, size, (sk->sk_sndbuf >> 1) - 64);

  		/* allow fallback to order-0 allocations */
  		size = min_t(int, size, SKB_MAX_HEAD(0) + UNIX_SKB_FRAGS_SZ);

  		data_len = max_t(int, 0, size - SKB_MAX_HEAD(0));

  		data_len = min_t(size_t, size, PAGE_ALIGN(data_len));

  		skb = sock_alloc_send_pskb(sk, size - data_len, data_len,

  					   msg->msg_flags & MSG_DONTWAIT, &err,
  					   get_order(UNIX_SKB_FRAGS_SZ));

  		if (!skb)

  			goto out_err;

  		/* Only send the fds in the first buffer */

  		err = unix_scm_to_skb(&scm, skb, !fds_sent);

  		if (err < 0) {

  			kfree_skb(skb);

  			goto out_err;

  		}

  		fds_sent = true;

  		skb_put(skb, size - data_len);
  		skb->data_len = data_len;
  		skb->len = size;

  		err = skb_copy_datagram_from_iter(skb, 0, &msg->msg_iter, size);

  		if (err) {

  			kfree_skb(skb);

  			goto out_err;

  		}

  		unix_state_lock(other);

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

  		maybe_add_creds(skb, sock, other);

  		skb_queue_tail(&other->sk_receive_queue, skb);

  		unix_state_unlock(other);

  		other->sk_data_ready(other);

  		sent += size;

  	}

  	scm_destroy(&scm);

  
  	return sent;
  
  pipe_err_free: