Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

9 files changed, 4938 insertions, 0 deletions

diff --git a/net/unix/Kconfig b/net/unix/Kconfig
new file mode 100644
index 000000000..b7f811216
--- /dev/null
+++ b/net/unix/Kconfig
@@ -0,0 +1,39 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Unix Domain Sockets
+#
+
+config UNIX
+	tristate "Unix domain sockets"
+	help
+	  If you say Y here, you will include support for Unix domain sockets;
+	  sockets are the standard Unix mechanism for establishing and
+	  accessing network connections.  Many commonly used programs such as
+	  the X Window system and syslog use these sockets even if your
+	  machine is not connected to any network.  Unless you are working on
+	  an embedded system or something similar, you therefore definitely
+	  want to say Y here.
+
+	  To compile this driver as a module, choose M here: the module will be
+	  called unix.  Note that several important services won't work
+	  correctly if you say M here and then neglect to load the module.
+
+	  Say Y unless you know what you are doing.
+
+config UNIX_SCM
+	bool
+	depends on UNIX
+	default y
+
+config	AF_UNIX_OOB
+	bool
+	depends on UNIX
+	default y
+
+config UNIX_DIAG
+	tristate "UNIX: socket monitoring interface"
+	depends on UNIX
+	default n
+	help
+	  Support for UNIX socket monitoring interface used by the ss tool.
+	  If unsure, say Y.
diff --git a/net/unix/Makefile b/net/unix/Makefile
new file mode 100644
index 000000000..20491825b
--- /dev/null
+++ b/net/unix/Makefile
@@ -0,0 +1,15 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for the Linux unix domain socket layer.
+#
+
+obj-$(CONFIG_UNIX)	+= unix.o
+
+unix-y			:= af_unix.o garbage.o
+unix-$(CONFIG_SYSCTL)	+= sysctl_net_unix.o
+unix-$(CONFIG_BPF_SYSCALL) += unix_bpf.o
+
+obj-$(CONFIG_UNIX_DIAG)	+= unix_diag.o
+unix_diag-y		:= diag.o
+
+obj-$(CONFIG_UNIX_SCM)	+= scm.o
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
new file mode 100644
index 000000000..be2ed7b0f
--- /dev/null
+++ b/net/unix/af_unix.c
@@ -0,0 +1,3785 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * NET4:	Implementation of BSD Unix domain sockets.
+ *
+ * Authors:	Alan Cox, <alan@lxorguk.ukuu.org.uk>
+ *
+ * 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/filter.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>
+#include <linux/btf_ids.h>
+
+#include "scm.h"
+
+static atomic_long_t unix_nr_socks;
+static struct hlist_head bsd_socket_buckets[UNIX_HASH_SIZE / 2];
+static spinlock_t bsd_socket_locks[UNIX_HASH_SIZE / 2];
+
+/* SMP locking strategy:
+ *    hash table is protected with spinlock.
+ *    each socket state is protected by separate spinlock.
+ */
+
+static unsigned int unix_unbound_hash(struct sock *sk)
+{
+	unsigned long hash = (unsigned long)sk;
+
+	hash ^= hash >> 16;
+	hash ^= hash >> 8;
+	hash ^= sk->sk_type;
+
+	return hash & UNIX_HASH_MOD;
+}
+
+static unsigned int unix_bsd_hash(struct inode *i)
+{
+	return i->i_ino & UNIX_HASH_MOD;
+}
+
+static unsigned int unix_abstract_hash(struct sockaddr_un *sunaddr,
+				       int addr_len, int type)
+{
+	__wsum csum = csum_partial(sunaddr, addr_len, 0);
+	unsigned int hash;
+
+	hash = (__force unsigned int)csum_fold(csum);
+	hash ^= hash >> 8;
+	hash ^= type;
+
+	return UNIX_HASH_MOD + 1 + (hash & UNIX_HASH_MOD);
+}
+
+static void unix_table_double_lock(struct net *net,
+				   unsigned int hash1, unsigned int hash2)
+{
+	if (hash1 == hash2) {
+		spin_lock(&net->unx.table.locks[hash1]);
+		return;
+	}
+
+	if (hash1 > hash2)
+		swap(hash1, hash2);
+
+	spin_lock(&net->unx.table.locks[hash1]);
+	spin_lock_nested(&net->unx.table.locks[hash2], SINGLE_DEPTH_NESTING);
+}
+
+static void unix_table_double_unlock(struct net *net,
+				     unsigned int hash1, unsigned int hash2)
+{
+	if (hash1 == hash2) {
+		spin_unlock(&net->unx.table.locks[hash1]);
+		return;
+	}
+
+	spin_unlock(&net->unx.table.locks[hash1]);
+	spin_unlock(&net->unx.table.locks[hash2]);
+}
+
+#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 */
+
+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(const struct sock *sk)
+{
+	return skb_queue_len(&sk->sk_receive_queue) > sk->sk_max_ack_backlog;
+}
+
+static inline int unix_recvq_full_lockless(const struct sock *sk)
+{
+	return skb_queue_len_lockless(&sk->sk_receive_queue) >
+		READ_ONCE(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 struct unix_address *unix_create_addr(struct sockaddr_un *sunaddr,
+					     int addr_len)
+{
+	struct unix_address *addr;
+
+	addr = kmalloc(sizeof(*addr) + addr_len, GFP_KERNEL);
+	if (!addr)
+		return NULL;
+
+	refcount_set(&addr->refcnt, 1);
+	addr->len = addr_len;
+	memcpy(addr->name, sunaddr, addr_len);
+
+	return addr;
+}
+
+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_validate_addr(struct sockaddr_un *sunaddr, int addr_len)
+{
+	if (addr_len <= offsetof(struct sockaddr_un, sun_path) ||
+	    addr_len > sizeof(*sunaddr))
+		return -EINVAL;
+
+	if (sunaddr->sun_family != AF_UNIX)
+		return -EINVAL;
+
+	return 0;
+}
+
+static void unix_mkname_bsd(struct sockaddr_un *sunaddr, int addr_len)
+{
+	/* 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 because syscall functions always pass
+	 * a pointer of struct sockaddr_storage which has a bigger buffer
+	 * than 108.
+	 */
+	((char *)sunaddr)[addr_len] = 0;
+}
+
+static void __unix_remove_socket(struct sock *sk)
+{
+	sk_del_node_init(sk);
+}
+
+static void __unix_insert_socket(struct net *net, struct sock *sk)
+{
+	DEBUG_NET_WARN_ON_ONCE(!sk_unhashed(sk));
+	sk_add_node(sk, &net->unx.table.buckets[sk->sk_hash]);
+}
+
+static void __unix_set_addr_hash(struct net *net, struct sock *sk,
+				 struct unix_address *addr, unsigned int hash)
+{
+	__unix_remove_socket(sk);
+	smp_store_release(&unix_sk(sk)->addr, addr);
+
+	sk->sk_hash = hash;
+	__unix_insert_socket(net, sk);
+}
+
+static void unix_remove_socket(struct net *net, struct sock *sk)
+{
+	spin_lock(&net->unx.table.locks[sk->sk_hash]);
+	__unix_remove_socket(sk);
+	spin_unlock(&net->unx.table.locks[sk->sk_hash]);
+}
+
+static void unix_insert_unbound_socket(struct net *net, struct sock *sk)
+{
+	spin_lock(&net->unx.table.locks[sk->sk_hash]);
+	__unix_insert_socket(net, sk);
+	spin_unlock(&net->unx.table.locks[sk->sk_hash]);
+}
+
+static void unix_insert_bsd_socket(struct sock *sk)
+{
+	spin_lock(&bsd_socket_locks[sk->sk_hash]);
+	sk_add_bind_node(sk, &bsd_socket_buckets[sk->sk_hash]);
+	spin_unlock(&bsd_socket_locks[sk->sk_hash]);
+}
+
+static void unix_remove_bsd_socket(struct sock *sk)
+{
+	if (!hlist_unhashed(&sk->sk_bind_node)) {
+		spin_lock(&bsd_socket_locks[sk->sk_hash]);
+		__sk_del_bind_node(sk);
+		spin_unlock(&bsd_socket_locks[sk->sk_hash]);
+
+		sk_node_init(&sk->sk_bind_node);
+	}
+}
+
+static struct sock *__unix_find_socket_byname(struct net *net,
+					      struct sockaddr_un *sunname,
+					      int len, unsigned int hash)
+{
+	struct sock *s;
+
+	sk_for_each(s, &net->unx.table.buckets[hash]) {
+		struct unix_sock *u = unix_sk(s);
+
+		if (u->addr->len == len &&
+		    !memcmp(u->addr->name, sunname, len))
+			return s;
+	}
+	return NULL;
+}
+
+static inline struct sock *unix_find_socket_byname(struct net *net,
+						   struct sockaddr_un *sunname,
+						   int len, unsigned int hash)
+{
+	struct sock *s;
+
+	spin_lock(&net->unx.table.locks[hash]);
+	s = __unix_find_socket_byname(net, sunname, len, hash);
+	if (s)
+		sock_hold(s);
+	spin_unlock(&net->unx.table.locks[hash]);
+	return s;
+}
+
+static struct sock *unix_find_socket_byinode(struct inode *i)
+{
+	unsigned int hash = unix_bsd_hash(i);
+	struct sock *s;
+
+	spin_lock(&bsd_socket_locks[hash]);
+	sk_for_each_bound(s, &bsd_socket_buckets[hash]) {
+		struct dentry *dentry = unix_sk(s)->path.dentry;
+
+		if (dentry && d_backing_inode(dentry) == i) {
+			sock_hold(s);
+			spin_unlock(&bsd_socket_locks[hash]);
+			return s;
+		}
+	}
+	spin_unlock(&bsd_socket_locks[hash]);
+	return NULL;
+}
+
+/* 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_to_poll(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),
+				   EPOLLOUT |
+				   EPOLLWRNORM |
+				   EPOLLWRBAND);
+}
+
+/* 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 other is SOCK_DEAD, we want to make sure we signal
+	 * POLLOUT, such that a subsequent write() can get a
+	 * -ECONNREFUSED. Otherwise, if we haven't queued any skbs
+	 * to other and its full, we will hang waiting for POLLOUT.
+	 */
+	if (unix_recvq_full_lockless(other) && !sock_flag(other, SOCK_DEAD))
+		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,
+				EPOLLOUT | EPOLLWRNORM | EPOLLWRBAND);
+		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;
+			sk_error_report(other);
+		}
+	}
+	other->sk_state = TCP_CLOSE;
+}
+
+static void unix_sock_destructor(struct sock *sk)
+{
+	struct unix_sock *u = unix_sk(sk);
+
+	skb_queue_purge(&sk->sk_receive_queue);
+
+	DEBUG_NET_WARN_ON_ONCE(refcount_read(&sk->sk_wmem_alloc));
+	DEBUG_NET_WARN_ON_ONCE(!sk_unhashed(sk));
+	DEBUG_NET_WARN_ON_ONCE(sk->sk_socket);
+	if (!sock_flag(sk, SOCK_DEAD)) {
+		pr_info("Attempt to release alive unix socket: %p\n", sk);
+		return;
+	}
+
+	if (u->addr)
+		unix_release_addr(u->addr);
+
+	atomic_long_dec(&unix_nr_socks);
+	sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
+#ifdef UNIX_REFCNT_DEBUG
+	pr_debug("UNIX %p is destroyed, %ld are still alive.\n", 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 sock *skpair;
+	struct sk_buff *skb;
+	struct path path;
+	int state;
+
+	unix_remove_socket(sock_net(sk), sk);
+	unix_remove_bsd_socket(sk);
+
+	/* Clear state */
+	unix_state_lock(sk);
+	sock_orphan(sk);
+	WRITE_ONCE(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;
+
+	skpair = unix_peer(sk);
+	unix_peer(sk) = NULL;
+
+	unix_state_unlock(sk);
+
+#if IS_ENABLED(CONFIG_AF_UNIX_OOB)
+	if (u->oob_skb) {
+		kfree_skb(u->oob_skb);
+		u->oob_skb = NULL;
+	}
+#endif
+
+	wake_up_interruptible_all(&u->peer_wait);
+
+	if (skpair != NULL) {
+		if (sk->sk_type == SOCK_STREAM || sk->sk_type == SOCK_SEQPACKET) {
+			unix_state_lock(skpair);
+			/* No more writes */
+			WRITE_ONCE(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 */
+	}
+
+	/* 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 (READ_ONCE(unix_tot_inflight))
+		unix_gc();		/* Garbage collect fds */
+}
+
+static void init_peercred(struct sock *sk)
+{
+	const struct cred *old_cred;
+	struct pid *old_pid;
+
+	spin_lock(&sk->sk_peer_lock);
+	old_pid = sk->sk_peer_pid;
+	old_cred = sk->sk_peer_cred;
+	sk->sk_peer_pid  = get_pid(task_tgid(current));
+	sk->sk_peer_cred = get_current_cred();
+	spin_unlock(&sk->sk_peer_lock);
+
+	put_pid(old_pid);
+	put_cred(old_cred);
+}
+
+static void copy_peercred(struct sock *sk, struct sock *peersk)
+{
+	const struct cred *old_cred;
+	struct pid *old_pid;
+
+	if (sk < peersk) {
+		spin_lock(&sk->sk_peer_lock);
+		spin_lock_nested(&peersk->sk_peer_lock, SINGLE_DEPTH_NESTING);
+	} else {
+		spin_lock(&peersk->sk_peer_lock);
+		spin_lock_nested(&sk->sk_peer_lock, SINGLE_DEPTH_NESTING);
+	}
+	old_pid = sk->sk_peer_pid;
+	old_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);
+
+	spin_unlock(&sk->sk_peer_lock);
+	spin_unlock(&peersk->sk_peer_lock);
+
+	put_pid(old_pid);
+	put_cred(old_cred);
+}
+
+static int unix_listen(struct socket *sock, int backlog)
+{
+	int err;
+	struct sock *sk = sock->sk;
+	struct unix_sock *u = unix_sk(sk);
+
+	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);
+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);
+static __poll_t unix_poll(struct file *, struct socket *, poll_table *);
+static __poll_t unix_dgram_poll(struct file *, struct socket *,
+				    poll_table *);
+static int unix_ioctl(struct socket *, unsigned int, unsigned long);
+#ifdef CONFIG_COMPAT
+static int unix_compat_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg);
+#endif
+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_read_skb(struct sock *sk, skb_read_actor_t recv_actor);
+static int unix_stream_read_skb(struct sock *sk, skb_read_actor_t recv_actor);
+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;
+
+	WRITE_ONCE(sk->sk_peek_off, val);
+	mutex_unlock(&u->iolock);
+
+	return 0;
+}
+
+#ifdef CONFIG_PROC_FS
+static int unix_count_nr_fds(struct sock *sk)
+{
+	struct sk_buff *skb;
+	struct unix_sock *u;
+	int nr_fds = 0;
+
+	spin_lock(&sk->sk_receive_queue.lock);
+	skb = skb_peek(&sk->sk_receive_queue);
+	while (skb) {
+		u = unix_sk(skb->sk);
+		nr_fds += atomic_read(&u->scm_stat.nr_fds);
+		skb = skb_peek_next(skb, &sk->sk_receive_queue);
+	}
+	spin_unlock(&sk->sk_receive_queue.lock);
+
+	return nr_fds;
+}
+
+static void unix_show_fdinfo(struct seq_file *m, struct socket *sock)
+{
+	struct sock *sk = sock->sk;
+	struct unix_sock *u;
+	int nr_fds;
+
+	if (sk) {
+		u = unix_sk(sk);
+		if (sock->type == SOCK_DGRAM) {
+			nr_fds = atomic_read(&u->scm_stat.nr_fds);
+			goto out_print;
+		}
+
+		unix_state_lock(sk);
+		if (sk->sk_state != TCP_LISTEN)
+			nr_fds = atomic_read(&u->scm_stat.nr_fds);
+		else
+			nr_fds = unix_count_nr_fds(sk);
+		unix_state_unlock(sk);
+out_print:
+		seq_printf(m, "scm_fds: %u\n", nr_fds);
+	}
+}
+#else
+#define unix_show_fdinfo NULL
+#endif
+
+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,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl =	unix_compat_ioctl,
+#endif
+	.listen =	unix_listen,
+	.shutdown =	unix_shutdown,
+	.sendmsg =	unix_stream_sendmsg,
+	.recvmsg =	unix_stream_recvmsg,
+	.read_skb =	unix_stream_read_skb,
+	.mmap =		sock_no_mmap,
+	.sendpage =	unix_stream_sendpage,
+	.splice_read =	unix_stream_splice_read,
+	.set_peek_off =	unix_set_peek_off,
+	.show_fdinfo =	unix_show_fdinfo,
+};
+
+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,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl =	unix_compat_ioctl,
+#endif
+	.listen =	sock_no_listen,
+	.shutdown =	unix_shutdown,
+	.sendmsg =	unix_dgram_sendmsg,
+	.read_skb =	unix_read_skb,
+	.recvmsg =	unix_dgram_recvmsg,
+	.mmap =		sock_no_mmap,
+	.sendpage =	sock_no_sendpage,
+	.set_peek_off =	unix_set_peek_off,
+	.show_fdinfo =	unix_show_fdinfo,
+};
+
+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,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl =	unix_compat_ioctl,
+#endif
+	.listen =	unix_listen,
+	.shutdown =	unix_shutdown,
+	.sendmsg =	unix_seqpacket_sendmsg,
+	.recvmsg =	unix_seqpacket_recvmsg,
+	.mmap =		sock_no_mmap,
+	.sendpage =	sock_no_sendpage,
+	.set_peek_off =	unix_set_peek_off,
+	.show_fdinfo =	unix_show_fdinfo,
+};
+
+static void unix_close(struct sock *sk, long timeout)
+{
+	/* Nothing to do here, unix socket does not need a ->close().
+	 * This is merely for sockmap.
+	 */
+}
+
+static void unix_unhash(struct sock *sk)
+{
+	/* Nothing to do here, unix socket does not need a ->unhash().
+	 * This is merely for sockmap.
+	 */
+}
+
+struct proto unix_dgram_proto = {
+	.name			= "UNIX",
+	.owner			= THIS_MODULE,
+	.obj_size		= sizeof(struct unix_sock),
+	.close			= unix_close,
+#ifdef CONFIG_BPF_SYSCALL
+	.psock_update_sk_prot	= unix_dgram_bpf_update_proto,
+#endif
+};
+
+struct proto unix_stream_proto = {
+	.name			= "UNIX-STREAM",
+	.owner			= THIS_MODULE,
+	.obj_size		= sizeof(struct unix_sock),
+	.close			= unix_close,
+	.unhash			= unix_unhash,
+#ifdef CONFIG_BPF_SYSCALL
+	.psock_update_sk_prot	= unix_stream_bpf_update_proto,
+#endif
+};
+
+static struct sock *unix_create1(struct net *net, struct socket *sock, int kern, int type)
+{
+	struct unix_sock *u;
+	struct sock *sk;
+	int err;
+
+	atomic_long_inc(&unix_nr_socks);
+	if (atomic_long_read(&unix_nr_socks) > 2 * get_max_files()) {
+		err = -ENFILE;
+		goto err;
+	}
+
+	if (type == SOCK_STREAM)
+		sk = sk_alloc(net, PF_UNIX, GFP_KERNEL, &unix_stream_proto, kern);
+	else /*dgram and  seqpacket */
+		sk = sk_alloc(net, PF_UNIX, GFP_KERNEL, &unix_dgram_proto, kern);
+
+	if (!sk) {
+		err = -ENOMEM;
+		goto err;
+	}
+
+	sock_init_data(sock, sk);
+
+	sk->sk_hash		= unix_unbound_hash(sk);
+	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);
+	memset(&u->scm_stat, 0, sizeof(struct scm_stat));
+	unix_insert_unbound_socket(net, sk);
+
+	sock_prot_inuse_add(net, sk->sk_prot, 1);
+
+	return sk;
+
+err:
+	atomic_long_dec(&unix_nr_socks);
+	return ERR_PTR(err);
+}
+
+static int unix_create(struct net *net, struct socket *sock, int protocol,
+		       int kern)
+{
+	struct sock *sk;
+
+	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;
+		fallthrough;
+	case SOCK_DGRAM:
+		sock->ops = &unix_dgram_ops;
+		break;
+	case SOCK_SEQPACKET:
+		sock->ops = &unix_seqpacket_ops;
+		break;
+	default:
+		return -ESOCKTNOSUPPORT;
+	}
+
+	sk = unix_create1(net, sock, kern, sock->type);
+	if (IS_ERR(sk))
+		return PTR_ERR(sk);
+
+	return 0;
+}
+
+static int unix_release(struct socket *sock)
+{
+	struct sock *sk = sock->sk;
+
+	if (!sk)
+		return 0;
+
+	sk->sk_prot->close(sk, 0);
+	unix_release_sock(sk, 0);
+	sock->sk = NULL;
+
+	return 0;
+}
+
+static struct sock *unix_find_bsd(struct sockaddr_un *sunaddr, int addr_len,
+				  int type)
+{
+	struct inode *inode;
+	struct path path;
+	struct sock *sk;
+	int err;
+
+	unix_mkname_bsd(sunaddr, addr_len);
+	err = kern_path(sunaddr->sun_path, LOOKUP_FOLLOW, &path);
+	if (err)
+		goto fail;
+
+	err = path_permission(&path, MAY_WRITE);
+	if (err)
+		goto path_put;
+
+	err = -ECONNREFUSED;
+	inode = d_backing_inode(path.dentry);
+	if (!S_ISSOCK(inode->i_mode))
+		goto path_put;
+
+	sk = unix_find_socket_byinode(inode);
+	if (!sk)
+		goto path_put;
+
+	err = -EPROTOTYPE;
+	if (sk->sk_type == type)
+		touch_atime(&path);
+	else
+		goto sock_put;
+
+	path_put(&path);
+
+	return sk;
+
+sock_put:
+	sock_put(sk);
+path_put:
+	path_put(&path);
+fail:
+	return ERR_PTR(err);
+}
+
+static struct sock *unix_find_abstract(struct net *net,
+				       struct sockaddr_un *sunaddr,
+				       int addr_len, int type)
+{
+	unsigned int hash = unix_abstract_hash(sunaddr, addr_len, type);
+	struct dentry *dentry;
+	struct sock *sk;
+
+	sk = unix_find_socket_byname(net, sunaddr, addr_len, hash);
+	if (!sk)
+		return ERR_PTR(-ECONNREFUSED);
+
+	dentry = unix_sk(sk)->path.dentry;
+	if (dentry)
+		touch_atime(&unix_sk(sk)->path);
+
+	return sk;
+}
+
+static struct sock *unix_find_other(struct net *net,
+				    struct sockaddr_un *sunaddr,
+				    int addr_len, int type)
+{
+	struct sock *sk;
+
+	if (sunaddr->sun_path[0])
+		sk = unix_find_bsd(sunaddr, addr_len, type);
+	else
+		sk = unix_find_abstract(net, sunaddr, addr_len, type);
+
+	return sk;
+}
+
+static int unix_autobind(struct sock *sk)
+{
+	unsigned int new_hash, old_hash = sk->sk_hash;
+	struct unix_sock *u = unix_sk(sk);
+	struct net *net = sock_net(sk);
+	struct unix_address *addr;
+	u32 lastnum, ordernum;
+	int err;
+
+	err = mutex_lock_interruptible(&u->bindlock);
+	if (err)
+		return err;
+
+	if (u->addr)
+		goto out;
+
+	err = -ENOMEM;
+	addr = kzalloc(sizeof(*addr) +
+		       offsetof(struct sockaddr_un, sun_path) + 16, GFP_KERNEL);
+	if (!addr)
+		goto out;
+
+	addr->len = offsetof(struct sockaddr_un, sun_path) + 6;
+	addr->name->sun_family = AF_UNIX;
+	refcount_set(&addr->refcnt, 1);
+
+	ordernum = get_random_u32();
+	lastnum = ordernum & 0xFFFFF;
+retry:
+	ordernum = (ordernum + 1) & 0xFFFFF;
+	sprintf(addr->name->sun_path + 1, "%05x", ordernum);
+
+	new_hash = unix_abstract_hash(addr->name, addr->len, sk->sk_type);
+	unix_table_double_lock(net, old_hash, new_hash);
+
+	if (__unix_find_socket_byname(net, addr->name, addr->len, new_hash)) {
+		unix_table_double_unlock(net, old_hash, new_hash);
+
+		/* __unix_find_socket_byname() may take long time if many names
+		 * are already in use.
+		 */
+		cond_resched();
+
+		if (ordernum == lastnum) {
+			/* Give up if all names seems to be in use. */
+			err = -ENOSPC;
+			unix_release_addr(addr);
+			goto out;
+		}
+
+		goto retry;
+	}
+
+	__unix_set_addr_hash(net, sk, addr, new_hash);
+	unix_table_double_unlock(net, old_hash, new_hash);
+	err = 0;
+
+out:	mutex_unlock(&u->bindlock);
+	return err;
+}
+
+static int unix_bind_bsd(struct sock *sk, struct sockaddr_un *sunaddr,
+			 int addr_len)
+{
+	umode_t mode = S_IFSOCK |
+	       (SOCK_INODE(sk->sk_socket)->i_mode & ~current_umask());
+	unsigned int new_hash, old_hash = sk->sk_hash;
+	struct unix_sock *u = unix_sk(sk);
+	struct net *net = sock_net(sk);
+	struct user_namespace *ns; // barf...
+	struct unix_address *addr;
+	struct dentry *dentry;
+	struct path parent;
+	int err;
+
+	unix_mkname_bsd(sunaddr, addr_len);
+	addr_len = strlen(sunaddr->sun_path) +
+		offsetof(struct sockaddr_un, sun_path) + 1;
+
+	addr = unix_create_addr(sunaddr, addr_len);
+	if (!addr)
+		return -ENOMEM;
+
+	/*
+	 * Get the parent directory, calculate the hash for last
+	 * component.
+	 */
+	dentry = kern_path_create(AT_FDCWD, addr->name->sun_path, &parent, 0);
+	if (IS_ERR(dentry)) {
+		err = PTR_ERR(dentry);
+		goto out;
+	}
+
+	/*
+	 * All right, let's create it.
+	 */
+	ns = mnt_user_ns(parent.mnt);
+	err = security_path_mknod(&parent, dentry, mode, 0);
+	if (!err)
+		err = vfs_mknod(ns, d_inode(parent.dentry), dentry, mode, 0);
+	if (err)
+		goto out_path;
+	err = mutex_lock_interruptible(&u->bindlock);
+	if (err)
+		goto out_unlink;
+	if (u->addr)
+		goto out_unlock;
+
+	new_hash = unix_bsd_hash(d_backing_inode(dentry));
+	unix_table_double_lock(net, old_hash, new_hash);
+	u->path.mnt = mntget(parent.mnt);
+	u->path.dentry = dget(dentry);
+	__unix_set_addr_hash(net, sk, addr, new_hash);
+	unix_table_double_unlock(net, old_hash, new_hash);
+	unix_insert_bsd_socket(sk);
+	mutex_unlock(&u->bindlock);
+	done_path_create(&parent, dentry);
+	return 0;
+
+out_unlock:
+	mutex_unlock(&u->bindlock);
+	err = -EINVAL;
+out_unlink:
+	/* failed after successful mknod?  unlink what we'd created... */
+	vfs_unlink(ns, d_inode(parent.dentry), dentry, NULL);
+out_path:
+	done_path_create(&parent, dentry);
+out:
+	unix_release_addr(addr);
+	return err == -EEXIST ? -EADDRINUSE : err;
+}
+
+static int unix_bind_abstract(struct sock *sk, struct sockaddr_un *sunaddr,
+			      int addr_len)
+{
+	unsigned int new_hash, old_hash = sk->sk_hash;
+	struct unix_sock *u = unix_sk(sk);
+	struct net *net = sock_net(sk);
+	struct unix_address *addr;
+	int err;
+
+	addr = unix_create_addr(sunaddr, addr_len);
+	if (!addr)
+		return -ENOMEM;
+
+	err = mutex_lock_interruptible(&u->bindlock);
+	if (err)
+		goto out;
+
+	if (u->addr) {
+		err = -EINVAL;
+		goto out_mutex;
+	}
+
+	new_hash = unix_abstract_hash(addr->name, addr->len, sk->sk_type);
+	unix_table_double_lock(net, old_hash, new_hash);
+
+	if (__unix_find_socket_byname(net, addr->name, addr->len, new_hash))
+		goto out_spin;
+
+	__unix_set_addr_hash(net, sk, addr, new_hash);
+	unix_table_double_unlock(net, old_hash, new_hash);
+	mutex_unlock(&u->bindlock);
+	return 0;
+
+out_spin:
+	unix_table_double_unlock(net, old_hash, new_hash);
+	err = -EADDRINUSE;
+out_mutex:
+	mutex_unlock(&u->bindlock);
+out:
+	unix_release_addr(addr);
+	return err;
+}
+
+static int unix_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
+{
+	struct sockaddr_un *sunaddr = (struct sockaddr_un *)uaddr;
+	struct sock *sk = sock->sk;
+	int err;
+
+	if (addr_len == offsetof(struct sockaddr_un, sun_path) &&
+	    sunaddr->sun_family == AF_UNIX)
+		return unix_autobind(sk);
+
+	err = unix_validate_addr(sunaddr, addr_len);
+	if (err)
+		return err;
+
+	if (sunaddr->sun_path[0])
+		err = unix_bind_bsd(sk, sunaddr, addr_len);
+	else
+		err = unix_bind_abstract(sk, sunaddr, addr_len);
+
+	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 sockaddr_un *sunaddr = (struct sockaddr_un *)addr;
+	struct sock *sk = sock->sk;
+	struct sock *other;
+	int err;
+
+	err = -EINVAL;
+	if (alen < offsetofend(struct sockaddr, sa_family))
+		goto out;
+
+	if (addr->sa_family != AF_UNSPEC) {
+		err = unix_validate_addr(sunaddr, alen);
+		if (err)
+			goto out;
+
+		if (test_bit(SOCK_PASSCRED, &sock->flags) &&
+		    !unix_sk(sk)->addr) {
+			err = unix_autobind(sk);
+			if (err)
+				goto out;
+		}
+
+restart:
+		other = unix_find_other(sock_net(sk), sunaddr, alen, sock->type);
+		if (IS_ERR(other)) {
+			err = PTR_ERR(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;
+
+		sk->sk_state = other->sk_state = TCP_ESTABLISHED;
+	} 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;
+		if (!other)
+			sk->sk_state = TCP_CLOSE;
+		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)
+	__releases(&unix_sk(other)->lock)
+{
+	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_lockless(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, *newsk = NULL, *other = NULL;
+	struct unix_sock *u = unix_sk(sk), *newu, *otheru;
+	struct net *net = sock_net(sk);
+	struct sk_buff *skb = NULL;
+	long timeo;
+	int err;
+	int st;
+
+	err = unix_validate_addr(sunaddr, addr_len);
+	if (err)
+		goto out;
+
+	if (test_bit(SOCK_PASSCRED, &sock->flags) && !u->addr) {
+		err = unix_autobind(sk);
+		if (err)
+			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.
+	 */
+
+	/* create new sock for complete connection */
+	newsk = unix_create1(net, NULL, 0, sock->type);
+	if (IS_ERR(newsk)) {
+		err = PTR_ERR(newsk);
+		newsk = NULL;
+		goto out;
+	}
+
+	err = -ENOMEM;
+
+	/* 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);
+	if (IS_ERR(other)) {
+		err = PTR_ERR(other);
+		other = NULL;
+		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
+	 *
+	 * The contents of *(otheru->addr) and otheru->path
+	 * are seen fully set up here, since we have found
+	 * otheru in hash under its lock.  Insertion into the
+	 * hash chain we'd found it in had been done in an
+	 * earlier critical area protected by the chain's lock,
+	 * the same one where we'd set *(otheru->addr) contents,
+	 * as well as otheru->path and otheru->addr itself.
+	 *
+	 * Using smp_store_release() here to set newu->addr
+	 * is enough to make those stores, as well as stores
+	 * to newu->path visible to anyone who gets newu->addr
+	 * by smp_load_acquire().  IOW, the same warranties
+	 * as for unix_sock instances bound in unix_bind() or
+	 * in unix_autobind().
+	 */
+	if (otheru->path.dentry) {
+		path_get(&otheru->path);
+		newu->path = otheru->path;
+	}
+	refcount_inc(&otheru->addr->refcnt);
+	smp_store_release(&newu->addr, otheru->addr);
+
+	/* 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 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);
+
+	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, (flags & O_NONBLOCK) ? MSG_DONTWAIT : 0,
+				&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 peer)
+{
+	struct sock *sk = sock->sk;
+	struct unix_address *addr;
+	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);
+	}
+
+	addr = smp_load_acquire(&unix_sk(sk)->addr);
+	if (!addr) {
+		sunaddr->sun_family = AF_UNIX;
+		sunaddr->sun_path[0] = 0;
+		err = offsetof(struct sockaddr_un, sun_path);
+	} else {
+		err = addr->len;
+		memcpy(sunaddr, addr->name, addr->len);
+	}
+	sock_put(sk);
+out:
+	return err;
+}
+
+static void unix_peek_fds(struct scm_cookie *scm, struct sk_buff *skb)
+{
+	scm->fp = scm_fp_dup(UNIXCB(skb).fp);
+
+	/*
+	 * Garbage collection of unix sockets starts by selecting a set of
+	 * candidate sockets which have reference only from being in flight
+	 * (total_refs == inflight_refs).  This condition is checked once during
+	 * the candidate collection phase, and candidates are marked as such, so
+	 * that non-candidates can later be ignored.  While inflight_refs is
+	 * protected by unix_gc_lock, total_refs (file count) is not, hence this
+	 * is an instantaneous decision.
+	 *
+	 * Once a candidate, however, the socket must not be reinstalled into a
+	 * file descriptor while the garbage collection is in progress.
+	 *
+	 * If the above conditions are met, then the directed graph of
+	 * candidates (*) does not change while unix_gc_lock is held.
+	 *
+	 * Any operations that changes the file count through file descriptors
+	 * (dup, close, sendmsg) does not change the graph since candidates are
+	 * not installed in fds.
+	 *
+	 * Dequeing a candidate via recvmsg would install it into an fd, but
+	 * that takes unix_gc_lock to decrement the inflight count, so it's
+	 * serialized with garbage collection.
+	 *
+	 * MSG_PEEK is special in that it does not change the inflight count,
+	 * yet does install the socket into an fd.  The following lock/unlock
+	 * pair is to ensure serialization with garbage collection.  It must be
+	 * done between incrementing the file count and installing the file into
+	 * an fd.
+	 *
+	 * If garbage collection starts after the barrier provided by the
+	 * lock/unlock, then it will see the elevated refcount and not mark this
+	 * as a candidate.  If a garbage collection is already in progress
+	 * before the file count was incremented, then the lock/unlock pair will
+	 * ensure that garbage collection is finished before progressing to
+	 * installing the fd.
+	 *
+	 * (*) A -> B where B is on the queue of A or B is on the queue of C
+	 * which is on the queue of listening socket A.
+	 */
+	spin_lock(&unix_gc_lock);
+	spin_unlock(&unix_gc_lock);
+}
+
+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)
+{
+	return UNIXCB(skb).pid == scm->pid &&
+	       uid_eq(UNIXCB(skb).uid, scm->creds.uid) &&
+	       gid_eq(UNIXCB(skb).gid, scm->creds.gid) &&
+	       unix_secdata_eq(scm, skb);
+}
+
+static void scm_stat_add(struct sock *sk, struct sk_buff *skb)
+{
+	struct scm_fp_list *fp = UNIXCB(skb).fp;
+	struct unix_sock *u = unix_sk(sk);
+
+	if (unlikely(fp && fp->count))
+		atomic_add(fp->count, &u->scm_stat.nr_fds);
+}
+
+static void scm_stat_del(struct sock *sk, struct sk_buff *skb)
+{
+	struct scm_fp_list *fp = UNIXCB(skb).fp;
+	struct unix_sock *u = unix_sk(sk);
+
+	if (unlikely(fp && fp->count))
+		atomic_sub(fp->count, &u->scm_stat.nr_fds);
+}
+
+/*
+ *	Send AF_UNIX data.
+ */
+
+static int unix_dgram_sendmsg(struct socket *sock, struct msghdr *msg,
+			      size_t len)
+{
+	DECLARE_SOCKADDR(struct sockaddr_un *, sunaddr, msg->msg_name);
+	struct sock *sk = sock->sk, *other = NULL;
+	struct unix_sock *u = unix_sk(sk);
+	struct scm_cookie scm;
+	struct sk_buff *skb;
+	int data_len = 0;
+	int sk_locked;
+	long timeo;
+	int err;
+
+	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_validate_addr(sunaddr, msg->msg_namelen);
+		if (err)
+			goto out;
+	} 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(sk);
+		if (err)
+			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(sock_net(sk), sunaddr, msg->msg_namelen,
+					sk->sk_type);
+		if (IS_ERR(other)) {
+			err = PTR_ERR(other);
+			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 (sk->sk_type == SOCK_SEQPACKET) {
+			/* We are here only when racing with unix_release_sock()
+			 * is clearing @other. Never change state to TCP_CLOSE
+			 * unlike SOCK_DGRAM wants.
+			 */
+			unix_state_unlock(sk);
+			err = -EPIPE;
+		} else if (unix_peer(sk) == other) {
+			unix_peer(sk) = NULL;
+			unix_dgram_peer_wake_disconnect_wakeup(sk, other);
+
+			sk->sk_state = TCP_CLOSE;
+			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_lockless(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);
+	scm_stat_add(other, skb);
+	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 minimum of a full page.
+ */
+#define UNIX_SKB_FRAGS_SZ (PAGE_SIZE << get_order(32768))
+
+#if IS_ENABLED(CONFIG_AF_UNIX_OOB)
+static int queue_oob(struct socket *sock, struct msghdr *msg, struct sock *other,
+		     struct scm_cookie *scm, bool fds_sent)
+{
+	struct unix_sock *ousk = unix_sk(other);
+	struct sk_buff *skb;
+	int err = 0;
+
+	skb = sock_alloc_send_skb(sock->sk, 1, msg->msg_flags & MSG_DONTWAIT, &err);
+
+	if (!skb)
+		return err;
+
+	err = unix_scm_to_skb(scm, skb, !fds_sent);
+	if (err < 0) {
+		kfree_skb(skb);
+		return err;
+	}
+	skb_put(skb, 1);
+	err = skb_copy_datagram_from_iter(skb, 0, &msg->msg_iter, 1);
+
+	if (err) {
+		kfree_skb(skb);
+		return err;
+	}
+
+	unix_state_lock(other);
+
+	if (sock_flag(other, SOCK_DEAD) ||
+	    (other->sk_shutdown & RCV_SHUTDOWN)) {
+		unix_state_unlock(other);
+		kfree_skb(skb);
+		return -EPIPE;
+	}
+
+	maybe_add_creds(skb, sock, other);
+	skb_get(skb);
+
+	if (ousk->oob_skb)
+		consume_skb(ousk->oob_skb);
+
+	WRITE_ONCE(ousk->oob_skb, skb);
+
+	scm_stat_add(other, skb);
+	skb_queue_tail(&other->sk_receive_queue, skb);
+	sk_send_sigurg(other);
+	unix_state_unlock(other);
+	other->sk_data_ready(other);
+
+	return err;
+}
+#endif
+
+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) {
+#if IS_ENABLED(CONFIG_AF_UNIX_OOB)
+		if (len)
+			len--;
+		else
+#endif
+			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);
+		scm_stat_add(other, skb);
+		skb_queue_tail(&other->sk_receive_queue, skb);
+		unix_state_unlock(other);
+		other->sk_data_ready(other);
+		sent += size;
+	}
+
+#if IS_ENABLED(CONFIG_AF_UNIX_OOB)
+	if (msg->msg_flags & MSG_OOB) {
+		err = queue_oob(sock, msg, other, &scm, fds_sent);
+		if (err)
+			goto out_err;
+		sent++;
+	}
+#endif
+
+	scm_destroy(&scm);
+
+	return sent;
+
+pipe_err_free:
+	unix_state_unlock(other);
+	kfree_skb(skb);
+pipe_err:
+	if (sent == 0 && !(msg->msg_flags&MSG_NOSIGNAL))
+		send_sig(SIGPIPE, current, 0);
+	err = -EPIPE;
+out_err:
+	scm_destroy(&scm);
+	return sent ? : err;
+}
+
+static ssize_t unix_stream_sendpage(struct socket *socket, struct page *page,
+				    int offset, size_t size, int flags)
+{
+	int err;
+	bool send_sigpipe = false;
+	bool init_scm = true;
+	struct scm_cookie scm;
+	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:
+		spin_unlock(&other->sk_receive_queue.lock);
+		unix_state_unlock(other);
+		mutex_unlock(&unix_sk(other)->iolock);
+		newskb = sock_alloc_send_pskb(sk, 0, 0, flags & MSG_DONTWAIT,
+					      &err, 0);
+		if (!newskb)
+			goto err;
+	}
+
+	/* we must acquire iolock as we modify already present
+	 * skbs in the sk_receive_queue and mess with skb->len
+	 */
+	err = mutex_lock_interruptible(&unix_sk(other)->iolock);
+	if (err) {
+		err = flags & MSG_DONTWAIT ? -EAGAIN : -ERESTARTSYS;
+		goto err;
+	}
+
+	if (sk->sk_shutdown & SEND_SHUTDOWN) {
+		err = -EPIPE;
+		send_sigpipe = true;
+		goto err_unlock;
+	}
+
+	unix_state_lock(other);
+
+	if (sock_flag(other, SOCK_DEAD) ||
+	    other->sk_shutdown & RCV_SHUTDOWN) {
+		err = -EPIPE;
+		send_sigpipe = true;
+		goto err_state_unlock;
+	}
+
+	if (init_scm) {
+		err = maybe_init_creds(&scm, socket, other);
+		if (err)
+			goto err_state_unlock;
+		init_scm = false;
+	}
+
+	spin_lock(&other->sk_receive_queue.lock);
+	skb = skb_peek_tail(&other->sk_receive_queue);
+	if (tail && tail == skb) {
+		skb = newskb;
+	} else if (!skb || !unix_skb_scm_eq(skb, &scm)) {
+		if (newskb) {
+			skb = newskb;
+		} else {
+			tail = skb;
+			goto alloc_skb;
+		}
+	} 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);
+		newskb = NULL;
+	}
+
+	if (skb_append_pagefrags(skb, page, offset, size)) {
+		tail = skb;
+		goto alloc_skb;
+	}
+
+	skb->len += size;
+	skb->data_len += size;
+	skb->truesize += size;
+	refcount_add(size, &sk->sk_wmem_alloc);
+
+	if (newskb) {
+		unix_scm_to_skb(&scm, skb, false);
+		__skb_queue_tail(&other->sk_receive_queue, newskb);
+	}
+
+	spin_unlock(&other->sk_receive_queue.lock);
+	unix_state_unlock(other);
+	mutex_unlock(&unix_sk(other)->iolock);
+
+	other->sk_data_ready(other);
+	scm_destroy(&scm);
+	return size;
+
+err_state_unlock:
+	unix_state_unlock(other);
+err_unlock:
+	mutex_unlock(&unix_sk(other)->iolock);
+err:
+	kfree_skb(newskb);
+	if (send_sigpipe && !(flags & MSG_NOSIGNAL))
+		send_sig(SIGPIPE, current, 0);
+	if (!init_scm)
+		scm_destroy(&scm);
+	return err;
+}
+
+static int unix_seqpacket_sendmsg(struct socket *sock, struct msghdr *msg,
+				  size_t len)
+{
+	int err;
+	struct sock *sk = sock->sk;
+
+	err = sock_error(sk);
+	if (err)
+		return err;
+
+	if (sk->sk_state != TCP_ESTABLISHED)
+		return -ENOTCONN;
+
+	if (msg->msg_namelen)
+		msg->msg_namelen = 0;
+
+	return unix_dgram_sendmsg(sock, msg, len);
+}
+
+static int unix_seqpacket_recvmsg(struct socket *sock, struct msghdr *msg,
+				  size_t size, int flags)
+{
+	struct sock *sk = sock->sk;
+
+	if (sk->sk_state != TCP_ESTABLISHED)
+		return -ENOTCONN;
+
+	return unix_dgram_recvmsg(sock, msg, size, flags);
+}
+
+static void unix_copy_addr(struct msghdr *msg, struct sock *sk)
+{
+	struct unix_address *addr = smp_load_acquire(&unix_sk(sk)->addr);
+
+	if (addr) {
+		msg->msg_namelen = addr->len;
+		memcpy(msg->msg_name, addr->name, addr->len);
+	}
+}
+
+int __unix_dgram_recvmsg(struct sock *sk, struct msghdr *msg, size_t size,
+			 int flags)
+{
+	struct scm_cookie scm;
+	struct socket *sock = sk->sk_socket;
+	struct unix_sock *u = unix_sk(sk);
+	struct sk_buff *skb, *last;
+	long timeo;
+	int skip;
+	int err;
+
+	err = -EOPNOTSUPP;
+	if (flags&MSG_OOB)
+		goto out;
+
+	timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
+
+	do {
+		mutex_lock(&u->iolock);
+
+		skip = sk_peek_offset(sk, flags);
+		skb = __skb_try_recv_datagram(sk, &sk->sk_receive_queue, flags,
+					      &skip, &err, &last);
+		if (skb) {
+			if (!(flags & MSG_PEEK))
+				scm_stat_del(sk, skb);
+			break;
+		}
+
+		mutex_unlock(&u->iolock);
+
+		if (err != -EAGAIN)
+			break;
+	} while (timeo &&
+		 !__skb_wait_for_more_packets(sk, &sk->sk_receive_queue,
+					      &err, &timeo, last));
+
+	if (!skb) { /* implies iolock unlocked */
+		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);
+		goto out;
+	}
+
+	if (wq_has_sleeper(&u->peer_wait))
+		wake_up_interruptible_sync_poll(&u->peer_wait,
+						EPOLLOUT | EPOLLWRNORM |
+						EPOLLWRBAND);
+
+	if (msg->msg_name)
+		unix_copy_addr(msg, skb->sk);
+
+	if (size > skb->len - skip)
+		size = skb->len - skip;
+	else if (size < skb->len - skip)
+		msg->msg_flags |= MSG_TRUNC;
+
+	err = skb_copy_datagram_msg(skb, skip, msg, size);
+	if (err)
+		goto out_free;
+
+	if (sock_flag(sk, SOCK_RCVTSTAMP))
+		__sock_recv_timestamp(msg, sk, skb);
+
+	memset(&scm, 0, sizeof(scm));
+
+	scm_set_cred(&scm, UNIXCB(skb).pid, UNIXCB(skb).uid, UNIXCB(skb).gid);
+	unix_set_secdata(&scm, skb);
+
+	if (!(flags & MSG_PEEK)) {
+		if (UNIXCB(skb).fp)
+			unix_detach_fds(&scm, skb);
+
+		sk_peek_offset_bwd(sk, skb->len);
+	} else {
+		/* 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)
+
+		   POSIX 1003.1g does not actually define this clearly
+		   at all. POSIX 1003.1g doesn't define a lot of things
+		   clearly however!
+
+		*/
+
+		sk_peek_offset_fwd(sk, size);
+
+		if (UNIXCB(skb).fp)
+			unix_peek_fds(&scm, skb);
+	}
+	err = (flags & MSG_TRUNC) ? skb->len - skip : size;
+
+	scm_recv(sock, msg, &scm, flags);
+
+out_free:
+	skb_free_datagram(sk, skb);
+	mutex_unlock(&u->iolock);
+out:
+	return err;
+}
+
+static int unix_dgram_recvmsg(struct socket *sock, struct msghdr *msg, size_t size,
+			      int flags)
+{
+	struct sock *sk = sock->sk;
+
+#ifdef CONFIG_BPF_SYSCALL
+	const struct proto *prot = READ_ONCE(sk->sk_prot);
+
+	if (prot != &unix_dgram_proto)
+		return prot->recvmsg(sk, msg, size, flags, NULL);
+#endif
+	return __unix_dgram_recvmsg(sk, msg, size, flags);
+}
+
+static int unix_read_skb(struct sock *sk, skb_read_actor_t recv_actor)
+{
+	struct unix_sock *u = unix_sk(sk);
+	struct sk_buff *skb;
+	int err;
+
+	mutex_lock(&u->iolock);
+	skb = skb_recv_datagram(sk, MSG_DONTWAIT, &err);
+	mutex_unlock(&u->iolock);
+	if (!skb)
+		return err;
+
+	return recv_actor(sk, skb);
+}
+
+/*
+ *	Sleep until more data has arrived. But check for races..
+ */
+static long unix_stream_data_wait(struct sock *sk, long timeo,
+				  struct sk_buff *last, unsigned int last_len,
+				  bool freezable)
+{
+	unsigned int state = TASK_INTERRUPTIBLE | freezable * TASK_FREEZABLE;
+	struct sk_buff *tail;
+	DEFINE_WAIT(wait);
+
+	unix_state_lock(sk);
+
+	for (;;) {
+		prepare_to_wait(sk_sleep(sk), &wait, state);
+
+		tail = skb_peek_tail(&sk->sk_receive_queue);
+		if (tail != last ||
+		    (tail && tail->len != last_len) ||
+		    sk->sk_err ||
+		    (sk->sk_shutdown & RCV_SHUTDOWN) ||
+		    signal_pending(current) ||
+		    !timeo)
+			break;
+
+		sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk);
+		unix_state_unlock(sk);
+		timeo = schedule_timeout(timeo);
+		unix_state_lock(sk);
+
+		if (sock_flag(sk, SOCK_DEAD))
+			break;
+
+		sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk);
+	}
+
+	finish_wait(sk_sleep(sk), &wait);
+	unix_state_unlock(sk);
+	return timeo;
+}
+
+static unsigned int unix_skb_len(const struct sk_buff *skb)
+{
+	return skb->len - UNIXCB(skb).consumed;
+}
+
+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;
+};
+
+#if IS_ENABLED(CONFIG_AF_UNIX_OOB)
+static int unix_stream_recv_urg(struct unix_stream_read_state *state)
+{
+	struct socket *sock = state->socket;
+	struct sock *sk = sock->sk;
+	struct unix_sock *u = unix_sk(sk);
+	int chunk = 1;
+	struct sk_buff *oob_skb;
+
+	mutex_lock(&u->iolock);
+	unix_state_lock(sk);
+
+	if (sock_flag(sk, SOCK_URGINLINE) || !u->oob_skb) {
+		unix_state_unlock(sk);
+		mutex_unlock(&u->iolock);
+		return -EINVAL;
+	}
+
+	oob_skb = u->oob_skb;
+
+	if (!(state->flags & MSG_PEEK))
+		WRITE_ONCE(u->oob_skb, NULL);
+	else
+		skb_get(oob_skb);
+	unix_state_unlock(sk);
+
+	chunk = state->recv_actor(oob_skb, 0, chunk, state);
+
+	if (!(state->flags & MSG_PEEK))
+		UNIXCB(oob_skb).consumed += 1;
+
+	consume_skb(oob_skb);
+
+	mutex_unlock(&u->iolock);
+
+	if (chunk < 0)
+		return -EFAULT;
+
+	state->msg->msg_flags |= MSG_OOB;
+	return 1;
+}
+
+static struct sk_buff *manage_oob(struct sk_buff *skb, struct sock *sk,
+				  int flags, int copied)
+{
+	struct unix_sock *u = unix_sk(sk);
+
+	if (!unix_skb_len(skb) && !(flags & MSG_PEEK)) {
+		skb_unlink(skb, &sk->sk_receive_queue);
+		consume_skb(skb);
+		skb = NULL;
+	} else {
+		if (skb == u->oob_skb) {
+			if (copied) {
+				skb = NULL;
+			} else if (sock_flag(sk, SOCK_URGINLINE)) {
+				if (!(flags & MSG_PEEK)) {
+					WRITE_ONCE(u->oob_skb, NULL);
+					consume_skb(skb);
+				}
+			} else if (!(flags & MSG_PEEK)) {
+				skb_unlink(skb, &sk->sk_receive_queue);
+				consume_skb(skb);
+				skb = skb_peek(&sk->sk_receive_queue);
+			}
+		}
+	}
+	return skb;
+}
+#endif
+
+static int unix_stream_read_skb(struct sock *sk, skb_read_actor_t recv_actor)
+{
+	if (unlikely(sk->sk_state != TCP_ESTABLISHED))
+		return -ENOTCONN;
+
+	return unix_read_skb(sk, recv_actor);
+}
+
+static int unix_stream_read_generic(struct unix_stream_read_state *state,
+				    bool freezable)
+{
+	struct scm_cookie scm;
+	struct socket *sock = state->socket;
+	struct sock *sk = sock->sk;
+	struct unix_sock *u = unix_sk(sk);
+	int copied = 0;
+	int flags = state->flags;
+	int noblock = flags & MSG_DONTWAIT;
+	bool check_creds = false;
+	int target;
+	int err = 0;
+	long timeo;
+	int skip;
+	size_t size = state->size;
+	unsigned int last_len;
+
+	if (unlikely(sk->sk_state != TCP_ESTABLISHED)) {
+		err = -EINVAL;
+		goto out;
+	}
+
+	if (unlikely(flags & MSG_OOB)) {
+		err = -EOPNOTSUPP;
+#if IS_ENABLED(CONFIG_AF_UNIX_OOB)
+		err = unix_stream_recv_urg(state);
+#endif
+		goto out;
+	}
+
+	target = sock_rcvlowat(sk, flags & MSG_WAITALL, size);
+	timeo = sock_rcvtimeo(sk, noblock);
+
+	memset(&scm, 0, sizeof(scm));
+
+	/* Lock the socket to prevent queue disordering
+	 * while sleeps in memcpy_tomsg
+	 */
+	mutex_lock(&u->iolock);
+
+	skip = max(sk_peek_offset(sk, flags), 0);
+
+	do {
+		int chunk;
+		bool drop_skb;
+		struct sk_buff *skb, *last;
+
+redo:
+		unix_state_lock(sk);
+		if (sock_flag(sk, SOCK_DEAD)) {
+			err = -ECONNRESET;
+			goto unlock;
+		}
+		last = skb = skb_peek(&sk->sk_receive_queue);
+		last_len = last ? last->len : 0;
+
+#if IS_ENABLED(CONFIG_AF_UNIX_OOB)
+		if (skb) {
+			skb = manage_oob(skb, sk, flags, copied);
+			if (!skb) {
+				unix_state_unlock(sk);
+				if (copied)
+					break;
+				goto redo;
+			}
+		}
+#endif
+again:
+		if (skb == NULL) {
+			if (copied >= target)
+				goto unlock;
+
+			/*
+			 *	POSIX 1003.1g mandates this order.
+			 */
+
+			err = sock_error(sk);
+			if (err)
+				goto unlock;
+			if (sk->sk_shutdown & RCV_SHUTDOWN)
+				goto unlock;
+
+			unix_state_unlock(sk);
+			if (!timeo) {
+				err = -EAGAIN;
+				break;
+			}
+
+			mutex_unlock(&u->iolock);
+
+			timeo = unix_stream_data_wait(sk, timeo, last,
+						      last_len, freezable);
+
+			if (signal_pending(current)) {
+				err = sock_intr_errno(timeo);
+				scm_destroy(&scm);
+				goto out;
+			}
+
+			mutex_lock(&u->iolock);
+			goto redo;
+unlock:
+			unix_state_unlock(sk);
+			break;
+		}
+
+		while (skip >= unix_skb_len(skb)) {
+			skip -= unix_skb_len(skb);
+			last = skb;
+			last_len = skb->len;
+			skb = skb_peek_next(skb, &sk->sk_receive_queue);
+			if (!skb)
+				goto again;
+		}
+
+		unix_state_unlock(sk);
+
+		if (check_creds) {
+			/* Never glue messages from different writers */
+			if (!unix_skb_scm_eq(skb, &scm))
+				break;
+		} else if (test_bit(SOCK_PASSCRED, &sock->flags)) {
+			/* Copy credentials */
+			scm_set_cred(&scm, UNIXCB(skb).pid, UNIXCB(skb).uid, UNIXCB(skb).gid);
+			unix_set_secdata(&scm, skb);
+			check_creds = true;
+		}
+
+		/* Copy address just once */
+		if (state->msg && state->msg->msg_name) {
+			DECLARE_SOCKADDR(struct sockaddr_un *, sunaddr,
+					 state->msg->msg_name);
+			unix_copy_addr(state->msg, skb->sk);
+			sunaddr = NULL;
+		}
+
+		chunk = min_t(unsigned int, unix_skb_len(skb) - skip, size);
+		skb_get(skb);
+		chunk = state->recv_actor(skb, skip, chunk, state);
+		drop_skb = !unix_skb_len(skb);
+		/* skb is only safe to use if !drop_skb */
+		consume_skb(skb);
+		if (chunk < 0) {
+			if (copied == 0)
+				copied = -EFAULT;
+			break;
+		}
+		copied += chunk;
+		size -= chunk;
+
+		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;
+		}
+
+		/* Mark read part of skb as used */
+		if (!(flags & MSG_PEEK)) {
+			UNIXCB(skb).consumed += chunk;
+
+			sk_peek_offset_bwd(sk, chunk);
+
+			if (UNIXCB(skb).fp) {
+				scm_stat_del(sk, skb);
+				unix_detach_fds(&scm, skb);
+			}
+
+			if (unix_skb_len(skb))
+				break;
+
+			skb_unlink(skb, &sk->sk_receive_queue);
+			consume_skb(skb);
+
+			if (scm.fp)
+				break;
+		} else {
+			/* It is questionable, see note in unix_dgram_recvmsg.
+			 */
+			if (UNIXCB(skb).fp)
+				unix_peek_fds(&scm, skb);
+
+			sk_peek_offset_fwd(sk, chunk);
+
+			if (UNIXCB(skb).fp)
+				break;
+
+			skip = 0;
+			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);
+			break;
+		}
+	} while (size);
+
+	mutex_unlock(&u->iolock);
+	if (state->msg)
+		scm_recv(sock, state->msg, &scm, flags);
+	else
+		scm_destroy(&scm);
+out:
+	return copied ? : err;
+}
+
+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;
+}
+
+int __unix_stream_recvmsg(struct sock *sk, struct msghdr *msg,
+			  size_t size, int flags)
+{
+	struct unix_stream_read_state state = {
+		.recv_actor = unix_stream_read_actor,
+		.socket = sk->sk_socket,
+		.msg = msg,
+		.size = size,
+		.flags = flags
+	};
+
+	return unix_stream_read_generic(&state, true);
+}
+
+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
+	};
+
+#ifdef CONFIG_BPF_SYSCALL
+	struct sock *sk = sock->sk;
+	const struct proto *prot = READ_ONCE(sk->sk_prot);
+
+	if (prot != &unix_stream_proto)
+		return prot->recvmsg(sk, msg, size, flags, NULL);
+#endif
+	return unix_stream_read_generic(&state, true);
+}
+
+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);
+}
+
+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, false);
+}
+
+static int unix_shutdown(struct socket *sock, int mode)
+{
+	struct sock *sk = sock->sk;
+	struct sock *other;
+
+	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;
+
+	unix_state_lock(sk);
+	WRITE_ONCE(sk->sk_shutdown, 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;
+		const struct proto *prot = READ_ONCE(other->sk_prot);
+
+		if (prot->unhash)
+			prot->unhash(other);
+		if (mode&RCV_SHUTDOWN)
+			peer_mode |= SEND_SHUTDOWN;
+		if (mode&SEND_SHUTDOWN)
+			peer_mode |= RCV_SHUTDOWN;
+		unix_state_lock(other);
+		WRITE_ONCE(other->sk_shutdown, 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);
+	}
+	if (other)
+		sock_put(other);
+
+	return 0;
+}
+
+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)
+			amount += unix_skb_len(skb);
+	} 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);
+
+static int unix_open_file(struct sock *sk)
+{
+	struct path path;
+	struct file *f;
+	int fd;
+
+	if (!ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN))
+		return -EPERM;
+
+	if (!smp_load_acquire(&unix_sk(sk)->addr))
+		return -ENOENT;
+
+	path = unix_sk(sk)->path;
+	if (!path.dentry)
+		return -ENOENT;
+
+	path_get(&path);
+
+	fd = get_unused_fd_flags(O_CLOEXEC);
+	if (fd < 0)
+		goto out;
+
+	f = dentry_open(&path, O_PATH, current_cred());
+	if (IS_ERR(f)) {
+		put_unused_fd(fd);
+		fd = PTR_ERR(f);
+		goto out;
+	}
+
+	fd_install(fd, f);
+out:
+	path_put(&path);
+
+	return fd;
+}
+
+static int unix_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
+{
+	struct sock *sk = sock->sk;
+	long amount = 0;
+	int err;
+
+	switch (cmd) {
+	case SIOCOUTQ:
+		amount = unix_outq_len(sk);
+		err = put_user(amount, (int __user *)arg);
+		break;
+	case SIOCINQ:
+		amount = unix_inq_len(sk);
+		if (amount < 0)
+			err = amount;
+		else
+			err = put_user(amount, (int __user *)arg);
+		break;
+	case SIOCUNIXFILE:
+		err = unix_open_file(sk);
+		break;
+#if IS_ENABLED(CONFIG_AF_UNIX_OOB)
+	case SIOCATMARK:
+		{
+			struct sk_buff *skb;
+			int answ = 0;
+
+			skb = skb_peek(&sk->sk_receive_queue);
+			if (skb && skb == READ_ONCE(unix_sk(sk)->oob_skb))
+				answ = 1;
+			err = put_user(answ, (int __user *)arg);
+		}
+		break;
+#endif
+	default:
+		err = -ENOIOCTLCMD;
+		break;
+	}
+	return err;
+}
+
+#ifdef CONFIG_COMPAT
+static int unix_compat_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
+{
+	return unix_ioctl(sock, cmd, (unsigned long)compat_ptr(arg));
+}
+#endif
+
+static __poll_t unix_poll(struct file *file, struct socket *sock, poll_table *wait)
+{
+	struct sock *sk = sock->sk;
+	__poll_t mask;
+	u8 shutdown;
+
+	sock_poll_wait(file, sock, wait);
+	mask = 0;
+	shutdown = READ_ONCE(sk->sk_shutdown);
+
+	/* exceptional events? */
+	if (sk->sk_err)
+		mask |= EPOLLERR;
+	if (shutdown == SHUTDOWN_MASK)
+		mask |= EPOLLHUP;
+	if (shutdown & RCV_SHUTDOWN)
+		mask |= EPOLLRDHUP | EPOLLIN | EPOLLRDNORM;
+
+	/* readable? */
+	if (!skb_queue_empty_lockless(&sk->sk_receive_queue))
+		mask |= EPOLLIN | EPOLLRDNORM;
+	if (sk_is_readable(sk))
+		mask |= EPOLLIN | EPOLLRDNORM;
+#if IS_ENABLED(CONFIG_AF_UNIX_OOB)
+	if (READ_ONCE(unix_sk(sk)->oob_skb))
+		mask |= EPOLLPRI;
+#endif
+
+	/* Connection-based need to check for termination and startup */
+	if ((sk->sk_type == SOCK_STREAM || sk->sk_type == SOCK_SEQPACKET) &&
+	    sk->sk_state == TCP_CLOSE)
+		mask |= EPOLLHUP;
+
+	/*
+	 * we set writable also when the other side has shut down the
+	 * connection. This prevents stuck sockets.
+	 */
+	if (unix_writable(sk))
+		mask |= EPOLLOUT | EPOLLWRNORM | EPOLLWRBAND;
+
+	return mask;
+}
+
+static __poll_t unix_dgram_poll(struct file *file, struct socket *sock,
+				    poll_table *wait)
+{
+	struct sock *sk = sock->sk, *other;
+	unsigned int writable;
+	__poll_t mask;
+	u8 shutdown;
+
+	sock_poll_wait(file, sock, wait);
+	mask = 0;
+	shutdown = READ_ONCE(sk->sk_shutdown);
+
+	/* exceptional events? */
+	if (sk->sk_err || !skb_queue_empty_lockless(&sk->sk_error_queue))
+		mask |= EPOLLERR |
+			(sock_flag(sk, SOCK_SELECT_ERR_QUEUE) ? EPOLLPRI : 0);
+
+	if (shutdown & RCV_SHUTDOWN)
+		mask |= EPOLLRDHUP | EPOLLIN | EPOLLRDNORM;
+	if (shutdown == SHUTDOWN_MASK)
+		mask |= EPOLLHUP;
+
+	/* readable? */
+	if (!skb_queue_empty_lockless(&sk->sk_receive_queue))
+		mask |= EPOLLIN | EPOLLRDNORM;
+	if (sk_is_readable(sk))
+		mask |= EPOLLIN | EPOLLRDNORM;
+
+	/* Connection-based need to check for termination and startup */
+	if (sk->sk_type == SOCK_SEQPACKET) {
+		if (sk->sk_state == TCP_CLOSE)
+			mask |= EPOLLHUP;
+		/* connection hasn't started yet? */
+		if (sk->sk_state == TCP_SYN_SENT)
+			return mask;
+	}
+
+	/* No write status requested, avoid expensive OUT tests. */
+	if (!(poll_requested_events(wait) & (EPOLLWRBAND|EPOLLWRNORM|EPOLLOUT)))
+		return mask;
+
+	writable = unix_writable(sk);
+	if (writable) {
+		unix_state_lock(sk);
+
+		other = unix_peer(sk);
+		if (other && unix_peer(other) != sk &&
+		    unix_recvq_full_lockless(other) &&
+		    unix_dgram_peer_wake_me(sk, other))
+			writable = 0;
+
+		unix_state_unlock(sk);
+	}
+
+	if (writable)
+		mask |= EPOLLOUT | EPOLLWRNORM | EPOLLWRBAND;
+	else
+		sk_set_bit(SOCKWQ_ASYNC_NOSPACE, sk);
+
+	return mask;
+}
+
+#ifdef CONFIG_PROC_FS
+
+#define BUCKET_SPACE (BITS_PER_LONG - (UNIX_HASH_BITS + 1) - 1)
+
+#define get_bucket(x) ((x) >> BUCKET_SPACE)
+#define get_offset(x) ((x) & ((1UL << BUCKET_SPACE) - 1))
+#define set_bucket_offset(b, o) ((b) << BUCKET_SPACE | (o))
+
+static struct sock *unix_from_bucket(struct seq_file *seq, loff_t *pos)
+{
+	unsigned long offset = get_offset(*pos);
+	unsigned long bucket = get_bucket(*pos);
+	unsigned long count = 0;
+	struct sock *sk;
+
+	for (sk = sk_head(&seq_file_net(seq)->unx.table.buckets[bucket]);
+	     sk; sk = sk_next(sk)) {
+		if (++count == offset)
+			break;
+	}
+
+	return sk;
+}
+
+static struct sock *unix_get_first(struct seq_file *seq, loff_t *pos)
+{
+	unsigned long bucket = get_bucket(*pos);
+	struct net *net = seq_file_net(seq);
+	struct sock *sk;
+
+	while (bucket < UNIX_HASH_SIZE) {
+		spin_lock(&net->unx.table.locks[bucket]);
+
+		sk = unix_from_bucket(seq, pos);
+		if (sk)
+			return sk;
+
+		spin_unlock(&net->unx.table.locks[bucket]);
+
+		*pos = set_bucket_offset(++bucket, 1);
+	}
+
+	return NULL;
+}
+
+static struct sock *unix_get_next(struct seq_file *seq, struct sock *sk,
+				  loff_t *pos)
+{
+	unsigned long bucket = get_bucket(*pos);
+
+	sk = sk_next(sk);
+	if (sk)
+		return sk;
+
+
+	spin_unlock(&seq_file_net(seq)->unx.table.locks[bucket]);
+
+	*pos = set_bucket_offset(++bucket, 1);
+
+	return unix_get_first(seq, pos);
+}
+
+static void *unix_seq_start(struct seq_file *seq, loff_t *pos)
+{
+	if (!*pos)
+		return SEQ_START_TOKEN;
+
+	return unix_get_first(seq, pos);
+}
+
+static void *unix_seq_next(struct seq_file *seq, void *v, loff_t *pos)
+{
+	++*pos;
+
+	if (v == SEQ_START_TOKEN)
+		return unix_get_first(seq, pos);
+
+	return unix_get_next(seq, v, pos);
+}
+
+static void unix_seq_stop(struct seq_file *seq, void *v)
+{
+	struct sock *sk = v;
+
+	if (sk)
+		spin_unlock(&seq_file_net(seq)->unx.table.locks[sk->sk_hash]);
+}
+
+static int unix_seq_show(struct seq_file *seq, void *v)
+{
+
+	if (v == SEQ_START_TOKEN)
+		seq_puts(seq, "Num       RefCount Protocol Flags    Type St "
+			 "Inode Path\n");
+	else {
+		struct sock *s = v;
+		struct unix_sock *u = unix_sk(s);
+		unix_state_lock(s);
+
+		seq_printf(seq, "%pK: %08X %08X %08X %04X %02X %5lu",
+			s,
+			refcount_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) {	// under a hash table lock here
+			int i, len;
+			seq_putc(seq, ' ');
+
+			i = 0;
+			len = u->addr->len -
+				offsetof(struct sockaddr_un, sun_path);
+			if (u->addr->name->sun_path[0]) {
+				len--;
+			} else {
+				seq_putc(seq, '@');
+				i++;
+			}
+			for ( ; i < len; i++)
+				seq_putc(seq, u->addr->name->sun_path[i] ?:
+					 '@');
+		}
+		unix_state_unlock(s);
+		seq_putc(seq, '\n');
+	}
+
+	return 0;
+}
+
+static const struct seq_operations unix_seq_ops = {
+	.start  = unix_seq_start,
+	.next   = unix_seq_next,
+	.stop   = unix_seq_stop,
+	.show   = unix_seq_show,
+};
+
+#if IS_BUILTIN(CONFIG_UNIX) && defined(CONFIG_BPF_SYSCALL)
+struct bpf_unix_iter_state {
+	struct seq_net_private p;
+	unsigned int cur_sk;
+	unsigned int end_sk;
+	unsigned int max_sk;
+	struct sock **batch;
+	bool st_bucket_done;
+};
+
+struct bpf_iter__unix {
+	__bpf_md_ptr(struct bpf_iter_meta *, meta);
+	__bpf_md_ptr(struct unix_sock *, unix_sk);
+	uid_t uid __aligned(8);
+};
+
+static int unix_prog_seq_show(struct bpf_prog *prog, struct bpf_iter_meta *meta,
+			      struct unix_sock *unix_sk, uid_t uid)
+{
+	struct bpf_iter__unix ctx;
+
+	meta->seq_num--;  /* skip SEQ_START_TOKEN */
+	ctx.meta = meta;
+	ctx.unix_sk = unix_sk;
+	ctx.uid = uid;
+	return bpf_iter_run_prog(prog, &ctx);
+}
+
+static int bpf_iter_unix_hold_batch(struct seq_file *seq, struct sock *start_sk)
+
+{
+	struct bpf_unix_iter_state *iter = seq->private;
+	unsigned int expected = 1;
+	struct sock *sk;
+
+	sock_hold(start_sk);
+	iter->batch[iter->end_sk++] = start_sk;
+
+	for (sk = sk_next(start_sk); sk; sk = sk_next(sk)) {
+		if (iter->end_sk < iter->max_sk) {
+			sock_hold(sk);
+			iter->batch[iter->end_sk++] = sk;
+		}
+
+		expected++;
+	}
+
+	spin_unlock(&seq_file_net(seq)->unx.table.locks[start_sk->sk_hash]);
+
+	return expected;
+}
+
+static void bpf_iter_unix_put_batch(struct bpf_unix_iter_state *iter)
+{
+	while (iter->cur_sk < iter->end_sk)
+		sock_put(iter->batch[iter->cur_sk++]);
+}
+
+static int bpf_iter_unix_realloc_batch(struct bpf_unix_iter_state *iter,
+				       unsigned int new_batch_sz)
+{
+	struct sock **new_batch;
+
+	new_batch = kvmalloc(sizeof(*new_batch) * new_batch_sz,
+			     GFP_USER | __GFP_NOWARN);
+	if (!new_batch)
+		return -ENOMEM;
+
+	bpf_iter_unix_put_batch(iter);
+	kvfree(iter->batch);
+	iter->batch = new_batch;
+	iter->max_sk = new_batch_sz;
+
+	return 0;
+}
+
+static struct sock *bpf_iter_unix_batch(struct seq_file *seq,
+					loff_t *pos)
+{
+	struct bpf_unix_iter_state *iter = seq->private;
+	unsigned int expected;
+	bool resized = false;
+	struct sock *sk;
+
+	if (iter->st_bucket_done)
+		*pos = set_bucket_offset(get_bucket(*pos) + 1, 1);
+
+again:
+	/* Get a new batch */
+	iter->cur_sk = 0;
+	iter->end_sk = 0;
+
+	sk = unix_get_first(seq, pos);
+	if (!sk)
+		return NULL; /* Done */
+
+	expected = bpf_iter_unix_hold_batch(seq, sk);
+
+	if (iter->end_sk == expected) {
+		iter->st_bucket_done = true;
+		return sk;
+	}
+
+	if (!resized && !bpf_iter_unix_realloc_batch(iter, expected * 3 / 2)) {
+		resized = true;
+		goto again;
+	}
+
+	return sk;
+}
+
+static void *bpf_iter_unix_seq_start(struct seq_file *seq, loff_t *pos)
+{
+	if (!*pos)
+		return SEQ_START_TOKEN;
+
+	/* bpf iter does not support lseek, so it always
+	 * continue from where it was stop()-ped.
+	 */
+	return bpf_iter_unix_batch(seq, pos);
+}
+
+static void *bpf_iter_unix_seq_next(struct seq_file *seq, void *v, loff_t *pos)
+{
+	struct bpf_unix_iter_state *iter = seq->private;
+	struct sock *sk;
+
+	/* Whenever seq_next() is called, the iter->cur_sk is
+	 * done with seq_show(), so advance to the next sk in
+	 * the batch.
+	 */
+	if (iter->cur_sk < iter->end_sk)
+		sock_put(iter->batch[iter->cur_sk++]);
+
+	++*pos;
+
+	if (iter->cur_sk < iter->end_sk)
+		sk = iter->batch[iter->cur_sk];
+	else
+		sk = bpf_iter_unix_batch(seq, pos);
+
+	return sk;
+}
+
+static int bpf_iter_unix_seq_show(struct seq_file *seq, void *v)
+{
+	struct bpf_iter_meta meta;
+	struct bpf_prog *prog;
+	struct sock *sk = v;
+	uid_t uid;
+	bool slow;
+	int ret;
+
+	if (v == SEQ_START_TOKEN)
+		return 0;
+
+	slow = lock_sock_fast(sk);
+
+	if (unlikely(sk_unhashed(sk))) {
+		ret = SEQ_SKIP;
+		goto unlock;
+	}
+
+	uid = from_kuid_munged(seq_user_ns(seq), sock_i_uid(sk));
+	meta.seq = seq;
+	prog = bpf_iter_get_info(&meta, false);
+	ret = unix_prog_seq_show(prog, &meta, v, uid);
+unlock:
+	unlock_sock_fast(sk, slow);
+	return ret;
+}
+
+static void bpf_iter_unix_seq_stop(struct seq_file *seq, void *v)
+{
+	struct bpf_unix_iter_state *iter = seq->private;
+	struct bpf_iter_meta meta;
+	struct bpf_prog *prog;
+
+	if (!v) {
+		meta.seq = seq;
+		prog = bpf_iter_get_info(&meta, true);
+		if (prog)
+			(void)unix_prog_seq_show(prog, &meta, v, 0);
+	}
+
+	if (iter->cur_sk < iter->end_sk)
+		bpf_iter_unix_put_batch(iter);
+}
+
+static const struct seq_operations bpf_iter_unix_seq_ops = {
+	.start	= bpf_iter_unix_seq_start,
+	.next	= bpf_iter_unix_seq_next,
+	.stop	= bpf_iter_unix_seq_stop,
+	.show	= bpf_iter_unix_seq_show,
+};
+#endif
+#endif
+
+static const struct net_proto_family unix_family_ops = {
+	.family = PF_UNIX,
+	.create = unix_create,
+	.owner	= THIS_MODULE,
+};
+
+
+static int __net_init unix_net_init(struct net *net)
+{
+	int i;
+
+	net->unx.sysctl_max_dgram_qlen = 10;
+	if (unix_sysctl_register(net))
+		goto out;
+
+#ifdef CONFIG_PROC_FS
+	if (!proc_create_net("unix", 0, net->proc_net, &unix_seq_ops,
+			     sizeof(struct seq_net_private)))
+		goto err_sysctl;
+#endif
+
+	net->unx.table.locks = kvmalloc_array(UNIX_HASH_SIZE,
+					      sizeof(spinlock_t), GFP_KERNEL);
+	if (!net->unx.table.locks)
+		goto err_proc;
+
+	net->unx.table.buckets = kvmalloc_array(UNIX_HASH_SIZE,
+						sizeof(struct hlist_head),
+						GFP_KERNEL);
+	if (!net->unx.table.buckets)
+		goto free_locks;
+
+	for (i = 0; i < UNIX_HASH_SIZE; i++) {
+		spin_lock_init(&net->unx.table.locks[i]);
+		INIT_HLIST_HEAD(&net->unx.table.buckets[i]);
+	}
+
+	return 0;
+
+free_locks:
+	kvfree(net->unx.table.locks);
+err_proc:
+#ifdef CONFIG_PROC_FS
+	remove_proc_entry("unix", net->proc_net);
+err_sysctl:
+#endif
+	unix_sysctl_unregister(net);
+out:
+	return -ENOMEM;
+}
+
+static void __net_exit unix_net_exit(struct net *net)
+{
+	kvfree(net->unx.table.buckets);
+	kvfree(net->unx.table.locks);
+	unix_sysctl_unregister(net);
+	remove_proc_entry("unix", net->proc_net);
+}
+
+static struct pernet_operations unix_net_ops = {
+	.init = unix_net_init,
+	.exit = unix_net_exit,
+};
+
+#if IS_BUILTIN(CONFIG_UNIX) && defined(CONFIG_BPF_SYSCALL) && defined(CONFIG_PROC_FS)
+DEFINE_BPF_ITER_FUNC(unix, struct bpf_iter_meta *meta,
+		     struct unix_sock *unix_sk, uid_t uid)
+
+#define INIT_BATCH_SZ 16
+
+static int bpf_iter_init_unix(void *priv_data, struct bpf_iter_aux_info *aux)
+{
+	struct bpf_unix_iter_state *iter = priv_data;
+	int err;
+
+	err = bpf_iter_init_seq_net(priv_data, aux);
+	if (err)
+		return err;
+
+	err = bpf_iter_unix_realloc_batch(iter, INIT_BATCH_SZ);
+	if (err) {
+		bpf_iter_fini_seq_net(priv_data);
+		return err;
+	}
+
+	return 0;
+}
+
+static void bpf_iter_fini_unix(void *priv_data)
+{
+	struct bpf_unix_iter_state *iter = priv_data;
+
+	bpf_iter_fini_seq_net(priv_data);
+	kvfree(iter->batch);
+}
+
+static const struct bpf_iter_seq_info unix_seq_info = {
+	.seq_ops		= &bpf_iter_unix_seq_ops,
+	.init_seq_private	= bpf_iter_init_unix,
+	.fini_seq_private	= bpf_iter_fini_unix,
+	.seq_priv_size		= sizeof(struct bpf_unix_iter_state),
+};
+
+static const struct bpf_func_proto *
+bpf_iter_unix_get_func_proto(enum bpf_func_id func_id,
+			     const struct bpf_prog *prog)
+{
+	switch (func_id) {
+	case BPF_FUNC_setsockopt:
+		return &bpf_sk_setsockopt_proto;
+	case BPF_FUNC_getsockopt:
+		return &bpf_sk_getsockopt_proto;
+	default:
+		return NULL;
+	}
+}
+
+static struct bpf_iter_reg unix_reg_info = {
+	.target			= "unix",
+	.ctx_arg_info_size	= 1,
+	.ctx_arg_info		= {
+		{ offsetof(struct bpf_iter__unix, unix_sk),
+		  PTR_TO_BTF_ID_OR_NULL },
+	},
+	.get_func_proto         = bpf_iter_unix_get_func_proto,
+	.seq_info		= &unix_seq_info,
+};
+
+static void __init bpf_iter_register(void)
+{
+	unix_reg_info.ctx_arg_info[0].btf_id = btf_sock_ids[BTF_SOCK_TYPE_UNIX];
+	if (bpf_iter_reg_target(&unix_reg_info))
+		pr_warn("Warning: could not register bpf iterator unix\n");
+}
+#endif
+
+static int __init af_unix_init(void)
+{
+	int i, rc = -1;
+
+	BUILD_BUG_ON(sizeof(struct unix_skb_parms) > sizeof_field(struct sk_buff, cb));
+
+	for (i = 0; i < UNIX_HASH_SIZE / 2; i++) {
+		spin_lock_init(&bsd_socket_locks[i]);
+		INIT_HLIST_HEAD(&bsd_socket_buckets[i]);
+	}
+
+	rc = proto_register(&unix_dgram_proto, 1);
+	if (rc != 0) {
+		pr_crit("%s: Cannot create unix_sock SLAB cache!\n", __func__);
+		goto out;
+	}
+
+	rc = proto_register(&unix_stream_proto, 1);
+	if (rc != 0) {
+		pr_crit("%s: Cannot create unix_sock SLAB cache!\n", __func__);
+		proto_unregister(&unix_dgram_proto);
+		goto out;
+	}
+
+	sock_register(&unix_family_ops);
+	register_pernet_subsys(&unix_net_ops);
+	unix_bpf_build_proto();
+
+#if IS_BUILTIN(CONFIG_UNIX) && defined(CONFIG_BPF_SYSCALL) && defined(CONFIG_PROC_FS)
+	bpf_iter_register();
+#endif
+
+out:
+	return rc;
+}
+
+static void __exit af_unix_exit(void)
+{
+	sock_unregister(PF_UNIX);
+	proto_unregister(&unix_dgram_proto);
+	proto_unregister(&unix_stream_proto);
+	unregister_pernet_subsys(&unix_net_ops);
+}
+
+/* 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);
+module_exit(af_unix_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_NETPROTO(PF_UNIX);
diff --git a/net/unix/diag.c b/net/unix/diag.c
new file mode 100644
index 000000000..616b55c5b
--- /dev/null
+++ b/net/unix/diag.c
@@ -0,0 +1,342 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/types.h>
+#include <linux/spinlock.h>
+#include <linux/sock_diag.h>
+#include <linux/unix_diag.h>
+#include <linux/skbuff.h>
+#include <linux/module.h>
+#include <linux/uidgid.h>
+#include <net/netlink.h>
+#include <net/af_unix.h>
+#include <net/tcp_states.h>
+#include <net/sock.h>
+
+static int sk_diag_dump_name(struct sock *sk, struct sk_buff *nlskb)
+{
+	/* might or might not have a hash table lock */
+	struct unix_address *addr = smp_load_acquire(&unix_sk(sk)->addr);
+
+	if (!addr)
+		return 0;
+
+	return nla_put(nlskb, UNIX_DIAG_NAME,
+		       addr->len - offsetof(struct sockaddr_un, sun_path),
+		       addr->name->sun_path);
+}
+
+static int sk_diag_dump_vfs(struct sock *sk, struct sk_buff *nlskb)
+{
+	struct dentry *dentry = unix_sk(sk)->path.dentry;
+
+	if (dentry) {
+		struct unix_diag_vfs uv = {
+			.udiag_vfs_ino = d_backing_inode(dentry)->i_ino,
+			.udiag_vfs_dev = dentry->d_sb->s_dev,
+		};
+
+		return nla_put(nlskb, UNIX_DIAG_VFS, sizeof(uv), &uv);
+	}
+
+	return 0;
+}
+
+static int sk_diag_dump_peer(struct sock *sk, struct sk_buff *nlskb)
+{
+	struct sock *peer;
+	int ino;
+
+	peer = unix_peer_get(sk);
+	if (peer) {
+		unix_state_lock(peer);
+		ino = sock_i_ino(peer);
+		unix_state_unlock(peer);
+		sock_put(peer);
+
+		return nla_put_u32(nlskb, UNIX_DIAG_PEER, ino);
+	}
+
+	return 0;
+}
+
+static int sk_diag_dump_icons(struct sock *sk, struct sk_buff *nlskb)
+{
+	struct sk_buff *skb;
+	struct nlattr *attr;
+	u32 *buf;
+	int i;
+
+	if (sk->sk_state == TCP_LISTEN) {
+		spin_lock(&sk->sk_receive_queue.lock);
+
+		attr = nla_reserve(nlskb, UNIX_DIAG_ICONS,
+				   sk->sk_receive_queue.qlen * sizeof(u32));
+		if (!attr)
+			goto errout;
+
+		buf = nla_data(attr);
+		i = 0;
+		skb_queue_walk(&sk->sk_receive_queue, skb) {
+			struct sock *req, *peer;
+
+			req = skb->sk;
+			/*
+			 * The state lock is outer for the same sk's
+			 * queue lock. With the other's queue locked it's
+			 * OK to lock the state.
+			 */
+			unix_state_lock_nested(req);
+			peer = unix_sk(req)->peer;
+			buf[i++] = (peer ? sock_i_ino(peer) : 0);
+			unix_state_unlock(req);
+		}
+		spin_unlock(&sk->sk_receive_queue.lock);
+	}
+
+	return 0;
+
+errout:
+	spin_unlock(&sk->sk_receive_queue.lock);
+	return -EMSGSIZE;
+}
+
+static int sk_diag_show_rqlen(struct sock *sk, struct sk_buff *nlskb)
+{
+	struct unix_diag_rqlen rql;
+
+	if (sk->sk_state == TCP_LISTEN) {
+		rql.udiag_rqueue = sk->sk_receive_queue.qlen;
+		rql.udiag_wqueue = sk->sk_max_ack_backlog;
+	} else {
+		rql.udiag_rqueue = (u32) unix_inq_len(sk);
+		rql.udiag_wqueue = (u32) unix_outq_len(sk);
+	}
+
+	return nla_put(nlskb, UNIX_DIAG_RQLEN, sizeof(rql), &rql);
+}
+
+static int sk_diag_dump_uid(struct sock *sk, struct sk_buff *nlskb,
+			    struct user_namespace *user_ns)
+{
+	uid_t uid = from_kuid_munged(user_ns, sock_i_uid(sk));
+	return nla_put(nlskb, UNIX_DIAG_UID, sizeof(uid_t), &uid);
+}
+
+static int sk_diag_fill(struct sock *sk, struct sk_buff *skb, struct unix_diag_req *req,
+			struct user_namespace *user_ns,
+			u32 portid, u32 seq, u32 flags, int sk_ino)
+{
+	struct nlmsghdr *nlh;
+	struct unix_diag_msg *rep;
+
+	nlh = nlmsg_put(skb, portid, seq, SOCK_DIAG_BY_FAMILY, sizeof(*rep),
+			flags);
+	if (!nlh)
+		return -EMSGSIZE;
+
+	rep = nlmsg_data(nlh);
+	rep->udiag_family = AF_UNIX;
+	rep->udiag_type = sk->sk_type;
+	rep->udiag_state = sk->sk_state;
+	rep->pad = 0;
+	rep->udiag_ino = sk_ino;
+	sock_diag_save_cookie(sk, rep->udiag_cookie);
+
+	if ((req->udiag_show & UDIAG_SHOW_NAME) &&
+	    sk_diag_dump_name(sk, skb))
+		goto out_nlmsg_trim;
+
+	if ((req->udiag_show & UDIAG_SHOW_VFS) &&
+	    sk_diag_dump_vfs(sk, skb))
+		goto out_nlmsg_trim;
+
+	if ((req->udiag_show & UDIAG_SHOW_PEER) &&
+	    sk_diag_dump_peer(sk, skb))
+		goto out_nlmsg_trim;
+
+	if ((req->udiag_show & UDIAG_SHOW_ICONS) &&
+	    sk_diag_dump_icons(sk, skb))
+		goto out_nlmsg_trim;
+
+	if ((req->udiag_show & UDIAG_SHOW_RQLEN) &&
+	    sk_diag_show_rqlen(sk, skb))
+		goto out_nlmsg_trim;
+
+	if ((req->udiag_show & UDIAG_SHOW_MEMINFO) &&
+	    sock_diag_put_meminfo(sk, skb, UNIX_DIAG_MEMINFO))
+		goto out_nlmsg_trim;
+
+	if (nla_put_u8(skb, UNIX_DIAG_SHUTDOWN, sk->sk_shutdown))
+		goto out_nlmsg_trim;
+
+	if ((req->udiag_show & UDIAG_SHOW_UID) &&
+	    sk_diag_dump_uid(sk, skb, user_ns))
+		goto out_nlmsg_trim;
+
+	nlmsg_end(skb, nlh);
+	return 0;
+
+out_nlmsg_trim:
+	nlmsg_cancel(skb, nlh);
+	return -EMSGSIZE;
+}
+
+static int sk_diag_dump(struct sock *sk, struct sk_buff *skb, struct unix_diag_req *req,
+			struct user_namespace *user_ns,
+			u32 portid, u32 seq, u32 flags)
+{
+	int sk_ino;
+
+	unix_state_lock(sk);
+	sk_ino = sock_i_ino(sk);
+	unix_state_unlock(sk);
+
+	if (!sk_ino)
+		return 0;
+
+	return sk_diag_fill(sk, skb, req, user_ns, portid, seq, flags, sk_ino);
+}
+
+static int unix_diag_dump(struct sk_buff *skb, struct netlink_callback *cb)
+{
+	struct net *net = sock_net(skb->sk);
+	int num, s_num, slot, s_slot;
+	struct unix_diag_req *req;
+
+	req = nlmsg_data(cb->nlh);
+
+	s_slot = cb->args[0];
+	num = s_num = cb->args[1];
+
+	for (slot = s_slot; slot < UNIX_HASH_SIZE; s_num = 0, slot++) {
+		struct sock *sk;
+
+		num = 0;
+		spin_lock(&net->unx.table.locks[slot]);
+		sk_for_each(sk, &net->unx.table.buckets[slot]) {
+			if (num < s_num)
+				goto next;
+			if (!(req->udiag_states & (1 << sk->sk_state)))
+				goto next;
+			if (sk_diag_dump(sk, skb, req, sk_user_ns(skb->sk),
+					 NETLINK_CB(cb->skb).portid,
+					 cb->nlh->nlmsg_seq,
+					 NLM_F_MULTI) < 0) {
+				spin_unlock(&net->unx.table.locks[slot]);
+				goto done;
+			}
+next:
+			num++;
+		}
+		spin_unlock(&net->unx.table.locks[slot]);
+	}
+done:
+	cb->args[0] = slot;
+	cb->args[1] = num;
+
+	return skb->len;
+}
+
+static struct sock *unix_lookup_by_ino(struct net *net, unsigned int ino)
+{
+	struct sock *sk;
+	int i;
+
+	for (i = 0; i < UNIX_HASH_SIZE; i++) {
+		spin_lock(&net->unx.table.locks[i]);
+		sk_for_each(sk, &net->unx.table.buckets[i]) {
+			if (ino == sock_i_ino(sk)) {
+				sock_hold(sk);
+				spin_unlock(&net->unx.table.locks[i]);
+				return sk;
+			}
+		}
+		spin_unlock(&net->unx.table.locks[i]);
+	}
+	return NULL;
+}
+
+static int unix_diag_get_exact(struct sk_buff *in_skb,
+			       const struct nlmsghdr *nlh,
+			       struct unix_diag_req *req)
+{
+	struct net *net = sock_net(in_skb->sk);
+	unsigned int extra_len;
+	struct sk_buff *rep;
+	struct sock *sk;
+	int err;
+
+	err = -EINVAL;
+	if (req->udiag_ino == 0)
+		goto out_nosk;
+
+	sk = unix_lookup_by_ino(net, req->udiag_ino);
+	err = -ENOENT;
+	if (sk == NULL)
+		goto out_nosk;
+
+	err = sock_diag_check_cookie(sk, req->udiag_cookie);
+	if (err)
+		goto out;
+
+	extra_len = 256;
+again:
+	err = -ENOMEM;
+	rep = nlmsg_new(sizeof(struct unix_diag_msg) + extra_len, GFP_KERNEL);
+	if (!rep)
+		goto out;
+
+	err = sk_diag_fill(sk, rep, req, sk_user_ns(NETLINK_CB(in_skb).sk),
+			   NETLINK_CB(in_skb).portid,
+			   nlh->nlmsg_seq, 0, req->udiag_ino);
+	if (err < 0) {
+		nlmsg_free(rep);
+		extra_len += 256;
+		if (extra_len >= PAGE_SIZE)
+			goto out;
+
+		goto again;
+	}
+	err = nlmsg_unicast(net->diag_nlsk, rep, NETLINK_CB(in_skb).portid);
+
+out:
+	if (sk)
+		sock_put(sk);
+out_nosk:
+	return err;
+}
+
+static int unix_diag_handler_dump(struct sk_buff *skb, struct nlmsghdr *h)
+{
+	int hdrlen = sizeof(struct unix_diag_req);
+
+	if (nlmsg_len(h) < hdrlen)
+		return -EINVAL;
+
+	if (h->nlmsg_flags & NLM_F_DUMP) {
+		struct netlink_dump_control c = {
+			.dump = unix_diag_dump,
+		};
+		return netlink_dump_start(sock_net(skb->sk)->diag_nlsk, skb, h, &c);
+	} else
+		return unix_diag_get_exact(skb, h, nlmsg_data(h));
+}
+
+static const struct sock_diag_handler unix_diag_handler = {
+	.family = AF_UNIX,
+	.dump = unix_diag_handler_dump,
+};
+
+static int __init unix_diag_init(void)
+{
+	return sock_diag_register(&unix_diag_handler);
+}
+
+static void __exit unix_diag_exit(void)
+{
+	sock_diag_unregister(&unix_diag_handler);
+}
+
+module_init(unix_diag_init);
+module_exit(unix_diag_exit);
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_NET_PF_PROTO_TYPE(PF_NETLINK, NETLINK_SOCK_DIAG, 1 /* AF_LOCAL */);
diff --git a/net/unix/garbage.c b/net/unix/garbage.c
new file mode 100644
index 000000000..dc2763540
--- /dev/null
+++ b/net/unix/garbage.c
@@ -0,0 +1,335 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * NET3:	Garbage Collector For AF_UNIX sockets
+ *
+ * Garbage Collector:
+ *	Copyright (C) Barak A. Pearlmutter.
+ *
+ * Chopped about by Alan Cox 22/3/96 to make it fit the AF_UNIX socket problem.
+ * If it doesn't work blame me, it worked when Barak sent it.
+ *
+ * Assumptions:
+ *
+ *  - object w/ a bit
+ *  - free list
+ *
+ * Current optimizations:
+ *
+ *  - explicit stack instead of recursion
+ *  - tail recurse on first born instead of immediate push/pop
+ *  - we gather the stuff that should not be killed into tree
+ *    and stack is just a path from root to the current pointer.
+ *
+ *  Future optimizations:
+ *
+ *  - don't just push entire root set; process in place
+ *
+ *  Fixes:
+ *	Alan Cox	07 Sept	1997	Vmalloc internal stack as needed.
+ *					Cope with changing max_files.
+ *	Al Viro		11 Oct 1998
+ *		Graph may have cycles. That is, we can send the descriptor
+ *		of foo to bar and vice versa. Current code chokes on that.
+ *		Fix: move SCM_RIGHTS ones into the separate list and then
+ *		skb_free() them all instead of doing explicit fput's.
+ *		Another problem: since fput() may block somebody may
+ *		create a new unix_socket when we are in the middle of sweep
+ *		phase. Fix: revert the logic wrt MARKED. Mark everything
+ *		upon the beginning and unmark non-junk ones.
+ *
+ *		[12 Oct 1998] AAARGH! New code purges all SCM_RIGHTS
+ *		sent to connect()'ed but still not accept()'ed sockets.
+ *		Fixed. Old code had slightly different problem here:
+ *		extra fput() in situation when we passed the descriptor via
+ *		such socket and closed it (descriptor). That would happen on
+ *		each unix_gc() until the accept(). Since the struct file in
+ *		question would go to the free list and might be reused...
+ *		That might be the reason of random oopses on filp_close()
+ *		in unrelated processes.
+ *
+ *	AV		28 Feb 1999
+ *		Kill the explicit allocation of stack. Now we keep the tree
+ *		with root in dummy + pointer (gc_current) to one of the nodes.
+ *		Stack is represented as path from gc_current to dummy. Unmark
+ *		now means "add to tree". Push == "make it a son of gc_current".
+ *		Pop == "move gc_current to parent". We keep only pointers to
+ *		parents (->gc_tree).
+ *	AV		1 Mar 1999
+ *		Damn. Added missing check for ->dead in listen queues scanning.
+ *
+ *	Miklos Szeredi 25 Jun 2007
+ *		Reimplement with a cycle collecting algorithm. This should
+ *		solve several problems with the previous code, like being racy
+ *		wrt receive and holding up unrelated socket operations.
+ */
+
+#include <linux/kernel.h>
+#include <linux/string.h>
+#include <linux/socket.h>
+#include <linux/un.h>
+#include <linux/net.h>
+#include <linux/fs.h>
+#include <linux/skbuff.h>
+#include <linux/netdevice.h>
+#include <linux/file.h>
+#include <linux/proc_fs.h>
+#include <linux/mutex.h>
+#include <linux/wait.h>
+
+#include <net/sock.h>
+#include <net/af_unix.h>
+#include <net/scm.h>
+#include <net/tcp_states.h>
+
+#include "scm.h"
+
+/* Internal data structures and random procedures: */
+
+static LIST_HEAD(gc_candidates);
+static DECLARE_WAIT_QUEUE_HEAD(unix_gc_wait);
+
+static void scan_inflight(struct sock *x, void (*func)(struct unix_sock *),
+			  struct sk_buff_head *hitlist)
+{
+	struct sk_buff *skb;
+	struct sk_buff *next;
+
+	spin_lock(&x->sk_receive_queue.lock);
+	skb_queue_walk_safe(&x->sk_receive_queue, skb, next) {
+		/* Do we have file descriptors ? */
+		if (UNIXCB(skb).fp) {
+			bool hit = false;
+			/* Process the descriptors of this socket */
+			int nfd = UNIXCB(skb).fp->count;
+			struct file **fp = UNIXCB(skb).fp->fp;
+
+			while (nfd--) {
+				/* Get the socket the fd matches if it indeed does so */
+				struct sock *sk = unix_get_socket(*fp++);
+
+				if (sk) {
+					struct unix_sock *u = unix_sk(sk);
+
+					/* Ignore non-candidates, they could
+					 * have been added to the queues after
+					 * starting the garbage collection
+					 */
+					if (test_bit(UNIX_GC_CANDIDATE, &u->gc_flags)) {
+						hit = true;
+
+						func(u);
+					}
+				}
+			}
+			if (hit && hitlist != NULL) {
+				__skb_unlink(skb, &x->sk_receive_queue);
+				__skb_queue_tail(hitlist, skb);
+			}
+		}
+	}
+	spin_unlock(&x->sk_receive_queue.lock);
+}
+
+static void scan_children(struct sock *x, void (*func)(struct unix_sock *),
+			  struct sk_buff_head *hitlist)
+{
+	if (x->sk_state != TCP_LISTEN) {
+		scan_inflight(x, func, hitlist);
+	} else {
+		struct sk_buff *skb;
+		struct sk_buff *next;
+		struct unix_sock *u;
+		LIST_HEAD(embryos);
+
+		/* For a listening socket collect the queued embryos
+		 * and perform a scan on them as well.
+		 */
+		spin_lock(&x->sk_receive_queue.lock);
+		skb_queue_walk_safe(&x->sk_receive_queue, skb, next) {
+			u = unix_sk(skb->sk);
+
+			/* An embryo cannot be in-flight, so it's safe
+			 * to use the list link.
+			 */
+			BUG_ON(!list_empty(&u->link));
+			list_add_tail(&u->link, &embryos);
+		}
+		spin_unlock(&x->sk_receive_queue.lock);
+
+		while (!list_empty(&embryos)) {
+			u = list_entry(embryos.next, struct unix_sock, link);
+			scan_inflight(&u->sk, func, hitlist);
+			list_del_init(&u->link);
+		}
+	}
+}
+
+static void dec_inflight(struct unix_sock *usk)
+{
+	atomic_long_dec(&usk->inflight);
+}
+
+static void inc_inflight(struct unix_sock *usk)
+{
+	atomic_long_inc(&usk->inflight);
+}
+
+static void inc_inflight_move_tail(struct unix_sock *u)
+{
+	atomic_long_inc(&u->inflight);
+	/* If this still might be part of a cycle, move it to the end
+	 * of the list, so that it's checked even if it was already
+	 * passed over
+	 */
+	if (test_bit(UNIX_GC_MAYBE_CYCLE, &u->gc_flags))
+		list_move_tail(&u->link, &gc_candidates);
+}
+
+static bool gc_in_progress;
+#define UNIX_INFLIGHT_TRIGGER_GC 16000
+
+void wait_for_unix_gc(void)
+{
+	/* If number of inflight sockets is insane,
+	 * force a garbage collect right now.
+	 * Paired with the WRITE_ONCE() in unix_inflight(),
+	 * unix_notinflight() and gc_in_progress().
+	 */
+	if (READ_ONCE(unix_tot_inflight) > UNIX_INFLIGHT_TRIGGER_GC &&
+	    !READ_ONCE(gc_in_progress))
+		unix_gc();
+	wait_event(unix_gc_wait, gc_in_progress == false);
+}
+
+/* The external entry point: unix_gc() */
+void unix_gc(void)
+{
+	struct sk_buff *next_skb, *skb;
+	struct unix_sock *u;
+	struct unix_sock *next;
+	struct sk_buff_head hitlist;
+	struct list_head cursor;
+	LIST_HEAD(not_cycle_list);
+
+	spin_lock(&unix_gc_lock);
+
+	/* Avoid a recursive GC. */
+	if (gc_in_progress)
+		goto out;
+
+	/* Paired with READ_ONCE() in wait_for_unix_gc(). */
+	WRITE_ONCE(gc_in_progress, true);
+
+	/* First, select candidates for garbage collection.  Only
+	 * in-flight sockets are considered, and from those only ones
+	 * which don't have any external reference.
+	 *
+	 * Holding unix_gc_lock will protect these candidates from
+	 * being detached, and hence from gaining an external
+	 * reference.  Since there are no possible receivers, all
+	 * buffers currently on the candidates' queues stay there
+	 * during the garbage collection.
+	 *
+	 * We also know that no new candidate can be added onto the
+	 * receive queues.  Other, non candidate sockets _can_ be
+	 * added to queue, so we must make sure only to touch
+	 * candidates.
+	 */
+	list_for_each_entry_safe(u, next, &gc_inflight_list, link) {
+		long total_refs;
+		long inflight_refs;
+
+		total_refs = file_count(u->sk.sk_socket->file);
+		inflight_refs = atomic_long_read(&u->inflight);
+
+		BUG_ON(inflight_refs < 1);
+		BUG_ON(total_refs < inflight_refs);
+		if (total_refs == inflight_refs) {
+			list_move_tail(&u->link, &gc_candidates);
+			__set_bit(UNIX_GC_CANDIDATE, &u->gc_flags);
+			__set_bit(UNIX_GC_MAYBE_CYCLE, &u->gc_flags);
+		}
+	}
+
+	/* Now remove all internal in-flight reference to children of
+	 * the candidates.
+	 */
+	list_for_each_entry(u, &gc_candidates, link)
+		scan_children(&u->sk, dec_inflight, NULL);
+
+	/* Restore the references for children of all candidates,
+	 * which have remaining references.  Do this recursively, so
+	 * only those remain, which form cyclic references.
+	 *
+	 * Use a "cursor" link, to make the list traversal safe, even
+	 * though elements might be moved about.
+	 */
+	list_add(&cursor, &gc_candidates);
+	while (cursor.next != &gc_candidates) {
+		u = list_entry(cursor.next, struct unix_sock, link);
+
+		/* Move cursor to after the current position. */
+		list_move(&cursor, &u->link);
+
+		if (atomic_long_read(&u->inflight) > 0) {
+			list_move_tail(&u->link, &not_cycle_list);
+			__clear_bit(UNIX_GC_MAYBE_CYCLE, &u->gc_flags);
+			scan_children(&u->sk, inc_inflight_move_tail, NULL);
+		}
+	}
+	list_del(&cursor);
+
+	/* Now gc_candidates contains only garbage.  Restore original
+	 * inflight counters for these as well, and remove the skbuffs
+	 * which are creating the cycle(s).
+	 */
+	skb_queue_head_init(&hitlist);
+	list_for_each_entry(u, &gc_candidates, link)
+		scan_children(&u->sk, inc_inflight, &hitlist);
+
+	/* not_cycle_list contains those sockets which do not make up a
+	 * cycle.  Restore these to the inflight list.
+	 */
+	while (!list_empty(&not_cycle_list)) {
+		u = list_entry(not_cycle_list.next, struct unix_sock, link);
+		__clear_bit(UNIX_GC_CANDIDATE, &u->gc_flags);
+		list_move_tail(&u->link, &gc_inflight_list);
+	}
+
+	spin_unlock(&unix_gc_lock);
+
+	/* We need io_uring to clean its registered files, ignore all io_uring
+	 * originated skbs. It's fine as io_uring doesn't keep references to
+	 * other io_uring instances and so killing all other files in the cycle
+	 * will put all io_uring references forcing it to go through normal
+	 * release.path eventually putting registered files.
+	 */
+	skb_queue_walk_safe(&hitlist, skb, next_skb) {
+		if (skb->scm_io_uring) {
+			__skb_unlink(skb, &hitlist);
+			skb_queue_tail(&skb->sk->sk_receive_queue, skb);
+		}
+	}
+
+	/* Here we are. Hitlist is filled. Die. */
+	__skb_queue_purge(&hitlist);
+
+	spin_lock(&unix_gc_lock);
+
+	/* There could be io_uring registered files, just push them back to
+	 * the inflight list
+	 */
+	list_for_each_entry_safe(u, next, &gc_candidates, link)
+		list_move_tail(&u->link, &gc_inflight_list);
+
+	/* All candidates should have been detached by now. */
+	BUG_ON(!list_empty(&gc_candidates));
+
+	/* Paired with READ_ONCE() in wait_for_unix_gc(). */
+	WRITE_ONCE(gc_in_progress, false);
+
+	wake_up(&unix_gc_wait);
+
+ out:
+	spin_unlock(&unix_gc_lock);
+}
diff --git a/net/unix/scm.c b/net/unix/scm.c
new file mode 100644
index 000000000..e8e2a00bb
--- /dev/null
+++ b/net/unix/scm.c
@@ -0,0 +1,154 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/string.h>
+#include <linux/socket.h>
+#include <linux/net.h>
+#include <linux/fs.h>
+#include <net/af_unix.h>
+#include <net/scm.h>
+#include <linux/init.h>
+#include <linux/io_uring.h>
+
+#include "scm.h"
+
+unsigned int unix_tot_inflight;
+EXPORT_SYMBOL(unix_tot_inflight);
+
+LIST_HEAD(gc_inflight_list);
+EXPORT_SYMBOL(gc_inflight_list);
+
+DEFINE_SPINLOCK(unix_gc_lock);
+EXPORT_SYMBOL(unix_gc_lock);
+
+struct sock *unix_get_socket(struct file *filp)
+{
+	struct sock *u_sock = NULL;
+	struct inode *inode = file_inode(filp);
+
+	/* Socket ? */
+	if (S_ISSOCK(inode->i_mode) && !(filp->f_mode & FMODE_PATH)) {
+		struct socket *sock = SOCKET_I(inode);
+		struct sock *s = sock->sk;
+
+		/* PF_UNIX ? */
+		if (s && sock->ops && sock->ops->family == PF_UNIX)
+			u_sock = s;
+	} else {
+		/* Could be an io_uring instance */
+		u_sock = io_uring_get_socket(filp);
+	}
+	return u_sock;
+}
+EXPORT_SYMBOL(unix_get_socket);
+
+/* Keep the number of times in flight count for the file
+ * descriptor if it is for an AF_UNIX socket.
+ */
+void unix_inflight(struct user_struct *user, struct file *fp)
+{
+	struct sock *s = unix_get_socket(fp);
+
+	spin_lock(&unix_gc_lock);
+
+	if (s) {
+		struct unix_sock *u = unix_sk(s);
+
+		if (atomic_long_inc_return(&u->inflight) == 1) {
+			BUG_ON(!list_empty(&u->link));
+			list_add_tail(&u->link, &gc_inflight_list);
+		} else {
+			BUG_ON(list_empty(&u->link));
+		}
+		/* Paired with READ_ONCE() in wait_for_unix_gc() */
+		WRITE_ONCE(unix_tot_inflight, unix_tot_inflight + 1);
+	}
+	WRITE_ONCE(user->unix_inflight, user->unix_inflight + 1);
+	spin_unlock(&unix_gc_lock);
+}
+
+void unix_notinflight(struct user_struct *user, struct file *fp)
+{
+	struct sock *s = unix_get_socket(fp);
+
+	spin_lock(&unix_gc_lock);
+
+	if (s) {
+		struct unix_sock *u = unix_sk(s);
+
+		BUG_ON(!atomic_long_read(&u->inflight));
+		BUG_ON(list_empty(&u->link));
+
+		if (atomic_long_dec_and_test(&u->inflight))
+			list_del_init(&u->link);
+		/* Paired with READ_ONCE() in wait_for_unix_gc() */
+		WRITE_ONCE(unix_tot_inflight, unix_tot_inflight - 1);
+	}
+	WRITE_ONCE(user->unix_inflight, user->unix_inflight - 1);
+	spin_unlock(&unix_gc_lock);
+}
+
+/*
+ * 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(READ_ONCE(user->unix_inflight) > task_rlimit(p, RLIMIT_NOFILE)))
+		return !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN);
+	return false;
+}
+
+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;
+}
+EXPORT_SYMBOL(unix_attach_fds);
+
+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]);
+}
+EXPORT_SYMBOL(unix_detach_fds);
+
+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);
+}
+EXPORT_SYMBOL(unix_destruct_scm);
diff --git a/net/unix/scm.h b/net/unix/scm.h
new file mode 100644
index 000000000..5a255a477
--- /dev/null
+++ b/net/unix/scm.h
@@ -0,0 +1,10 @@
+#ifndef NET_UNIX_SCM_H
+#define NET_UNIX_SCM_H
+
+extern struct list_head gc_inflight_list;
+extern spinlock_t unix_gc_lock;
+
+int unix_attach_fds(struct scm_cookie *scm, struct sk_buff *skb);
+void unix_detach_fds(struct scm_cookie *scm, struct sk_buff *skb);
+
+#endif
diff --git a/net/unix/sysctl_net_unix.c b/net/unix/sysctl_net_unix.c
new file mode 100644
index 000000000..500129aa7
--- /dev/null
+++ b/net/unix/sysctl_net_unix.c
@@ -0,0 +1,60 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * NET4:	Sysctl interface to net af_unix subsystem.
+ *
+ * Authors:	Mike Shaver.
+ */
+
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/sysctl.h>
+
+#include <net/af_unix.h>
+
+static struct ctl_table unix_table[] = {
+	{
+		.procname	= "max_dgram_qlen",
+		.data		= &init_net.unx.sysctl_max_dgram_qlen,
+		.maxlen		= sizeof(int),
+		.mode		= 0644,
+		.proc_handler	= proc_dointvec
+	},
+	{ }
+};
+
+int __net_init unix_sysctl_register(struct net *net)
+{
+	struct ctl_table *table;
+
+	if (net_eq(net, &init_net)) {
+		table = unix_table;
+	} else {
+		table = kmemdup(unix_table, sizeof(unix_table), GFP_KERNEL);
+		if (!table)
+			goto err_alloc;
+
+		table[0].data = &net->unx.sysctl_max_dgram_qlen;
+	}
+
+	net->unx.ctl = register_net_sysctl(net, "net/unix", table);
+	if (net->unx.ctl == NULL)
+		goto err_reg;
+
+	return 0;
+
+err_reg:
+	if (!net_eq(net, &init_net))
+		kfree(table);
+err_alloc:
+	return -ENOMEM;
+}
+
+void unix_sysctl_unregister(struct net *net)
+{
+	struct ctl_table *table;
+
+	table = net->unx.ctl->ctl_table_arg;
+	unregister_net_sysctl_table(net->unx.ctl);
+	if (!net_eq(net, &init_net))
+		kfree(table);
+}
diff --git a/net/unix/unix_bpf.c b/net/unix/unix_bpf.c
new file mode 100644
index 000000000..bd84785bf
--- /dev/null
+++ b/net/unix/unix_bpf.c
@@ -0,0 +1,198 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2021 Cong Wang <cong.wang@bytedance.com> */
+
+#include <linux/skmsg.h>
+#include <linux/bpf.h>
+#include <net/sock.h>
+#include <net/af_unix.h>
+
+#define unix_sk_has_data(__sk, __psock)					\
+		({	!skb_queue_empty(&__sk->sk_receive_queue) ||	\
+			!skb_queue_empty(&__psock->ingress_skb) ||	\
+			!list_empty(&__psock->ingress_msg);		\
+		})
+
+static int unix_msg_wait_data(struct sock *sk, struct sk_psock *psock,
+			      long timeo)
+{
+	DEFINE_WAIT_FUNC(wait, woken_wake_function);
+	struct unix_sock *u = unix_sk(sk);
+	int ret = 0;
+
+	if (sk->sk_shutdown & RCV_SHUTDOWN)
+		return 1;
+
+	if (!timeo)
+		return ret;
+
+	add_wait_queue(sk_sleep(sk), &wait);
+	sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk);
+	if (!unix_sk_has_data(sk, psock)) {
+		mutex_unlock(&u->iolock);
+		wait_woken(&wait, TASK_INTERRUPTIBLE, timeo);
+		mutex_lock(&u->iolock);
+		ret = unix_sk_has_data(sk, psock);
+	}
+	sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk);
+	remove_wait_queue(sk_sleep(sk), &wait);
+	return ret;
+}
+
+static int __unix_recvmsg(struct sock *sk, struct msghdr *msg,
+			  size_t len, int flags)
+{
+	if (sk->sk_type == SOCK_DGRAM)
+		return __unix_dgram_recvmsg(sk, msg, len, flags);
+	else
+		return __unix_stream_recvmsg(sk, msg, len, flags);
+}
+
+static int unix_bpf_recvmsg(struct sock *sk, struct msghdr *msg,
+			    size_t len, int flags, int *addr_len)
+{
+	struct unix_sock *u = unix_sk(sk);
+	struct sk_psock *psock;
+	int copied;
+
+	if (!len)
+		return 0;
+
+	psock = sk_psock_get(sk);
+	if (unlikely(!psock))
+		return __unix_recvmsg(sk, msg, len, flags);
+
+	mutex_lock(&u->iolock);
+	if (!skb_queue_empty(&sk->sk_receive_queue) &&
+	    sk_psock_queue_empty(psock)) {
+		mutex_unlock(&u->iolock);
+		sk_psock_put(sk, psock);
+		return __unix_recvmsg(sk, msg, len, flags);
+	}
+
+msg_bytes_ready:
+	copied = sk_msg_recvmsg(sk, psock, msg, len, flags);
+	if (!copied) {
+		long timeo;
+		int data;
+
+		timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
+		data = unix_msg_wait_data(sk, psock, timeo);
+		if (data) {
+			if (!sk_psock_queue_empty(psock))
+				goto msg_bytes_ready;
+			mutex_unlock(&u->iolock);
+			sk_psock_put(sk, psock);
+			return __unix_recvmsg(sk, msg, len, flags);
+		}
+		copied = -EAGAIN;
+	}
+	mutex_unlock(&u->iolock);
+	sk_psock_put(sk, psock);
+	return copied;
+}
+
+static struct proto *unix_dgram_prot_saved __read_mostly;
+static DEFINE_SPINLOCK(unix_dgram_prot_lock);
+static struct proto unix_dgram_bpf_prot;
+
+static struct proto *unix_stream_prot_saved __read_mostly;
+static DEFINE_SPINLOCK(unix_stream_prot_lock);
+static struct proto unix_stream_bpf_prot;
+
+static void unix_dgram_bpf_rebuild_protos(struct proto *prot, const struct proto *base)
+{
+	*prot        = *base;
+	prot->close  = sock_map_close;
+	prot->recvmsg = unix_bpf_recvmsg;
+	prot->sock_is_readable = sk_msg_is_readable;
+}
+
+static void unix_stream_bpf_rebuild_protos(struct proto *prot,
+					   const struct proto *base)
+{
+	*prot        = *base;
+	prot->close  = sock_map_close;
+	prot->recvmsg = unix_bpf_recvmsg;
+	prot->sock_is_readable = sk_msg_is_readable;
+	prot->unhash  = sock_map_unhash;
+}
+
+static void unix_dgram_bpf_check_needs_rebuild(struct proto *ops)
+{
+	if (unlikely(ops != smp_load_acquire(&unix_dgram_prot_saved))) {
+		spin_lock_bh(&unix_dgram_prot_lock);
+		if (likely(ops != unix_dgram_prot_saved)) {
+			unix_dgram_bpf_rebuild_protos(&unix_dgram_bpf_prot, ops);
+			smp_store_release(&unix_dgram_prot_saved, ops);
+		}
+		spin_unlock_bh(&unix_dgram_prot_lock);
+	}
+}
+
+static void unix_stream_bpf_check_needs_rebuild(struct proto *ops)
+{
+	if (unlikely(ops != smp_load_acquire(&unix_stream_prot_saved))) {
+		spin_lock_bh(&unix_stream_prot_lock);
+		if (likely(ops != unix_stream_prot_saved)) {
+			unix_stream_bpf_rebuild_protos(&unix_stream_bpf_prot, ops);
+			smp_store_release(&unix_stream_prot_saved, ops);
+		}
+		spin_unlock_bh(&unix_stream_prot_lock);
+	}
+}
+
+int unix_dgram_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore)
+{
+	if (sk->sk_type != SOCK_DGRAM)
+		return -EOPNOTSUPP;
+
+	if (restore) {
+		sk->sk_write_space = psock->saved_write_space;
+		sock_replace_proto(sk, psock->sk_proto);
+		return 0;
+	}
+
+	unix_dgram_bpf_check_needs_rebuild(psock->sk_proto);
+	sock_replace_proto(sk, &unix_dgram_bpf_prot);
+	return 0;
+}
+
+int unix_stream_bpf_update_proto(struct sock *sk, struct sk_psock *psock, bool restore)
+{
+	struct sock *sk_pair;
+
+	/* Restore does not decrement the sk_pair reference yet because we must
+	 * keep the a reference to the socket until after an RCU grace period
+	 * and any pending sends have completed.
+	 */
+	if (restore) {
+		sk->sk_write_space = psock->saved_write_space;
+		sock_replace_proto(sk, psock->sk_proto);
+		return 0;
+	}
+
+	/* psock_update_sk_prot can be called multiple times if psock is
+	 * added to multiple maps and/or slots in the same map. There is
+	 * also an edge case where replacing a psock with itself can trigger
+	 * an extra psock_update_sk_prot during the insert process. So it
+	 * must be safe to do multiple calls. Here we need to ensure we don't
+	 * increment the refcnt through sock_hold many times. There will only
+	 * be a single matching destroy operation.
+	 */
+	if (!psock->sk_pair) {
+		sk_pair = unix_peer(sk);
+		sock_hold(sk_pair);
+		psock->sk_pair = sk_pair;
+	}
+
+	unix_stream_bpf_check_needs_rebuild(psock->sk_proto);
+	sock_replace_proto(sk, &unix_stream_bpf_prot);
+	return 0;
+}
+
+void __init unix_bpf_build_proto(void)
+{
+	unix_dgram_bpf_rebuild_protos(&unix_dgram_bpf_prot, &unix_dgram_proto);
+	unix_stream_bpf_rebuild_protos(&unix_stream_bpf_prot, &unix_stream_proto);
+
+}