blob: b0a4c6d08e0a6ab752d3f64d46e9b11af5321888 [file] [log] [blame]
// 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/splice.h>
#include <linux/freezer.h>
#include <linux/file.h>
#include <linux/btf_ids.h>
#include <linux/bpf-cgroup.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.
*/
#ifdef CONFIG_PROVE_LOCKING
#define cmp_ptr(l, r) (((l) > (r)) - ((l) < (r)))
static int unix_table_lock_cmp_fn(const struct lockdep_map *a,
const struct lockdep_map *b)
{
return cmp_ptr(a, b);
}
static int unix_state_lock_cmp_fn(const struct lockdep_map *_a,
const struct lockdep_map *_b)
{
const struct unix_sock *a, *b;
a = container_of(_a, struct unix_sock, lock.dep_map);
b = container_of(_b, struct unix_sock, lock.dep_map);
if (a->sk.sk_state == TCP_LISTEN) {
/* unix_stream_connect(): Before the 2nd unix_state_lock(),
*
* 1. a is TCP_LISTEN.
* 2. b is not a.
* 3. concurrent connect(b -> a) must fail.
*
* Except for 2. & 3., the b's state can be any possible
* value due to concurrent connect() or listen().
*
* 2. is detected in debug_spin_lock_before(), and 3. cannot
* be expressed as lock_cmp_fn.
*/
switch (b->sk.sk_state) {
case TCP_CLOSE:
case TCP_ESTABLISHED:
case TCP_LISTEN:
return -1;
default:
/* Invalid case. */
return 0;
}
}
/* Should never happen. Just to be symmetric. */
if (b->sk.sk_state == TCP_LISTEN) {
switch (b->sk.sk_state) {
case TCP_CLOSE:
case TCP_ESTABLISHED:
return 1;
default:
return 0;
}
}
/* unix_state_double_lock(): ascending address order. */
return cmp_ptr(a, b);
}
static int unix_recvq_lock_cmp_fn(const struct lockdep_map *_a,
const struct lockdep_map *_b)
{
const struct sock *a, *b;
a = container_of(_a, struct sock, sk_receive_queue.lock.dep_map);
b = container_of(_b, struct sock, sk_receive_queue.lock.dep_map);
/* unix_collect_skb(): listener -> embryo order. */
if (a->sk_state == TCP_LISTEN && unix_sk(b)->listener == a)
return -1;
/* Should never happen. Just to be symmetric. */
if (b->sk_state == TCP_LISTEN && unix_sk(a)->listener == b)
return 1;
return 0;
}
#endif
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(&net->unx.table.locks[hash2]);
}
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_lockless(const struct sock *sk)
{
return skb_queue_len_lockless(&sk->sk_receive_queue) > sk->sk_max_ack_backlog;
}
struct sock *unix_peer_get(struct sock *s)
{
struct sock *peer;
unix_state_lock(s);
peer = unix_peer(s);
if (peer)
sock_hold(peer);
unix_state_unlock(s);
return peer;
}
EXPORT_SYMBOL_GPL(unix_peer_get);
static 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 int unix_mkname_bsd(struct sockaddr_un *sunaddr, int addr_len)
{
struct sockaddr_storage *addr = (struct sockaddr_storage *)sunaddr;
short offset = offsetof(struct sockaddr_storage, __data);
BUILD_BUG_ON(offset != offsetof(struct sockaddr_un, sun_path));
/* 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. Also, we must terminate sun_path for strlen() in
* getname_kernel().
*/
addr->__data[addr_len - offset] = 0;
/* Don't pass sunaddr->sun_path to strlen(). Otherwise, 108 will
* cause panic if CONFIG_FORTIFY_SOURCE=y. Let __fortify_strlen()
* know the actual buffer.
*/
return strlen(addr->__data) + offset + 1;
}
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, unsigned char state)
{
return state != TCP_LISTEN &&
(refcount_read(&sk->sk_wmem_alloc) << 2) <= READ_ONCE(sk->sk_sndbuf);
}
static void unix_write_space(struct sock *sk)
{
struct socket_wq *wq;
rcu_read_lock();
if (unix_writable(sk, READ_ONCE(sk->sk_state))) {
wq = rcu_dereference(sk->sk_wq);
if (skwq_has_sleeper(wq))
wake_up_interruptible_sync_poll(&wq->wait,
EPOLLOUT | EPOLLWRNORM | EPOLLWRBAND);
sk_wake_async_rcu(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) {
WRITE_ONCE(other->sk_err, ECONNRESET);
sk_error_report(other);
}
}
}
static void unix_sock_destructor(struct sock *sk)
{
struct unix_sock *u = unix_sk(sk);
skb_queue_purge(&sk->sk_receive_queue);
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;
WRITE_ONCE(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_lockless(&sk->sk_receive_queue) || embrion)
WRITE_ONCE(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 */
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)
{
sk->sk_peer_pid = get_pid(task_tgid(current));
sk->sk_peer_cred = get_current_cred();
}
static void update_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;
init_peercred(sk);
spin_unlock(&sk->sk_peer_lock);
put_pid(old_pid);
put_cred(old_cred);
}
static void copy_peercred(struct sock *sk, struct sock *peersk)
{
lockdep_assert_held(&unix_sk(peersk)->lock);
spin_lock(&sk->sk_peer_lock);
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);
}
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 (!READ_ONCE(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;
WRITE_ONCE(sk->sk_state, TCP_LISTEN);
/* set credentials so connect can copy them */
update_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 *, struct proto_accept_arg *arg);
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_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);
#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;
unsigned char s_state;
struct unix_sock *u;
int nr_fds = 0;
if (sk) {
s_state = READ_ONCE(sk->sk_state);
u = unix_sk(sk);
/* SOCK_STREAM and SOCK_SEQPACKET sockets never change their
* sk_state after switching to TCP_ESTABLISHED or TCP_LISTEN.
* SOCK_DGRAM is ordinary. So, no lock is needed.
*/
if (sock->type == SOCK_DGRAM || s_state == TCP_ESTABLISHED)
nr_fds = atomic_read(&u->scm_stat.nr_fds);
else if (s_state == TCP_LISTEN)
nr_fds = unix_count_nr_fds(sk);
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,
.splice_read = unix_stream_splice_read,
.set_peek_off = sk_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,
.set_peek_off = sk_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,
.set_peek_off = sk_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.
*/
}
static bool unix_bpf_bypass_getsockopt(int level, int optname)
{
if (level == SOL_SOCKET) {
switch (optname) {
case SO_PEERPIDFD:
return true;
default:
return false;
}
}
return false;
}
struct proto unix_dgram_proto = {
.name = "UNIX",
.owner = THIS_MODULE,
.obj_size = sizeof(struct unix_sock),
.close = unix_close,
.bpf_bypass_getsockopt = unix_bpf_bypass_getsockopt,
#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,
.bpf_bypass_getsockopt = unix_bpf_bypass_getsockopt,
#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 = READ_ONCE(net->unx.sysctl_max_dgram_qlen);
sk->sk_destruct = unix_sock_destructor;
lock_set_cmp_fn(&sk->sk_receive_queue.lock, unix_recvq_lock_cmp_fn, NULL);
u = unix_sk(sk);
u->listener = NULL;
u->vertex = NULL;
u->path.dentry = NULL;
u->path.mnt = NULL;
spin_lock_init(&u->lock);
lock_set_cmp_fn(&u->lock, unix_state_lock_cmp_fn, NULL);
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)
{
struct unix_sock *u = unix_sk(sk);
unsigned int new_hash, old_hash;
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);
old_hash = sk->sk_hash;
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());
struct unix_sock *u = unix_sk(sk);
unsigned int new_hash, old_hash;
struct net *net = sock_net(sk);
struct mnt_idmap *idmap;
struct unix_address *addr;
struct dentry *dentry;
struct path parent;
int err;
addr_len = unix_mkname_bsd(sunaddr, addr_len);
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.
*/
idmap = mnt_idmap(parent.mnt);
err = security_path_mknod(&parent, dentry, mode, 0);
if (!err)
err = vfs_mknod(idmap, 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;
old_hash = sk->sk_hash;
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(idmap, 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)
{
struct unix_sock *u = unix_sk(sk);
unsigned int new_hash, old_hash;
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;
}
old_hash = sk->sk_hash;
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)
swap(sk1, sk2);
unix_state_lock(sk1);
unix_state_lock(sk2);
}
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;
err = BPF_CGROUP_RUN_PROG_UNIX_CONNECT_LOCK(sk, addr, &alen);
if (err)
goto out;
if ((test_bit(SOCK_PASSCRED, &sock->flags) ||
test_bit(SOCK_PASSPIDFD, &sock->flags)) &&
!READ_ONCE(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;
WRITE_ONCE(sk->sk_state, TCP_ESTABLISHED);
WRITE_ONCE(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)
WRITE_ONCE(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);
unix_state_lock(old_peer);
if (!unix_peer(old_peer))
WRITE_ONCE(old_peer->sk_state, TCP_CLOSE);
unix_state_unlock(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;
unsigned char state;
long timeo;
int err;
err = unix_validate_addr(sunaddr, addr_len);
if (err)
goto out;
err = BPF_CGROUP_RUN_PROG_UNIX_CONNECT_LOCK(sk, uaddr, &addr_len);
if (err)
goto out;
if ((test_bit(SOCK_PASSCRED, &sock->flags) ||
test_bit(SOCK_PASSPIDFD, &sock->flags)) &&
!READ_ONCE(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;
}
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_lockless(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;
}
/* self connect and simultaneous connect are eliminated
* by rejecting TCP_LISTEN socket to avoid deadlock.
*/
state = READ_ONCE(sk->sk_state);
if (unlikely(state != TCP_CLOSE)) {
err = state == TCP_ESTABLISHED ? -EISCONN : -EINVAL;
goto out_unlock;
}
unix_state_lock(sk);
if (unlikely(sk->sk_state != TCP_CLOSE)) {
err = sk->sk_state == TCP_ESTABLISHED ? -EISCONN : -EINVAL;
unix_state_unlock(sk);
goto out_unlock;
}
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);
newu->listener = other;
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;
WRITE_ONCE(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_PASSPIDFD, &old->flags))
set_bit(SOCK_PASSPIDFD, &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,
struct proto_accept_arg *arg)
{
struct sock *sk = sock->sk;
struct sk_buff *skb;
struct sock *tsk;
arg->err = -EOPNOTSUPP;
if (sock->type != SOCK_STREAM && sock->type != SOCK_SEQPACKET)
goto out;
arg->err = -EINVAL;
if (READ_ONCE(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, (arg->flags & O_NONBLOCK) ? MSG_DONTWAIT : 0,
&arg->err);
if (!skb) {
/* This means receive shutdown. */
if (arg->err == 0)
arg->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);
unix_update_edges(unix_sk(tsk));
newsock->state = SS_CONNECTED;
unix_sock_inherit_flags(sock, newsock);
sock_graft(tsk, newsock);
unix_state_unlock(tsk);
return 0;
out:
return arg->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);
if (peer)
BPF_CGROUP_RUN_SA_PROG(sk, uaddr, &err,
CGROUP_UNIX_GETPEERNAME);
else
BPF_CGROUP_RUN_SA_PROG(sk, uaddr, &err,
CGROUP_UNIX_GETSOCKNAME);
}
sock_put(sk);
out:
return err;
}
/* 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;
}
static int unix_attach_fds(struct scm_cookie *scm, struct sk_buff *skb)
{
if (too_many_unix_fds(current))
return -ETOOMANYREFS;
UNIXCB(skb).fp = scm->fp;
scm->fp = NULL;
if (unix_prepare_fpl(UNIXCB(skb).fp))
return -ENOMEM;
return 0;
}
static void unix_detach_fds(struct scm_cookie *scm, struct sk_buff *skb)
{
scm->fp = UNIXCB(skb).fp;
UNIXCB(skb).fp = NULL;
unix_destroy_fpl(scm->fp);
}
static void unix_peek_fds(struct scm_cookie *scm, struct sk_buff *skb)
{
scm->fp = scm_fp_dup(UNIXCB(skb).fp);
}
static void unix_destruct_scm(struct sk_buff *skb)
{
struct scm_cookie scm;
memset(&scm, 0, sizeof(scm));
scm.pid = UNIXCB(skb).pid;
if (UNIXCB(skb).fp)
unix_detach_fds(&scm, skb);
/* Alas, it calls VFS */
/* So fscking what? fput() had been SMP-safe since the last Summer */
scm_destroy(&scm);
sock_wfree(skb);
}
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) ||
test_bit(SOCK_PASSPIDFD, &sock->flags) ||
!other->sk_socket ||
test_bit(SOCK_PASSCRED, &other->sk_socket->flags) ||
test_bit(SOCK_PASSPIDFD, &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 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);
unix_add_edges(fp, u);
}
}
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);
unix_del_edges(fp);
}
}
/*
* 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;
err = scm_send(sock, msg, &scm, false);
if (err < 0)
return err;
wait_for_unix_gc(scm.fp);
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;
err = BPF_CGROUP_RUN_PROG_UNIX_SENDMSG_LOCK(sk,
msg->msg_name,
&msg->msg_namelen,
NULL);
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) ||
test_bit(SOCK_PASSPIDFD, &sock->flags)) &&
!READ_ONCE(u->addr)) {
err = unix_autobind(sk);
if (err)
goto out;
}
err = -EMSGSIZE;
if (len > READ_ONCE(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);
WRITE_ONCE(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);
scm_stat_add(other, skb);
spin_lock(&other->sk_receive_queue.lock);
if (ousk->oob_skb)
consume_skb(ousk->oob_skb);
WRITE_ONCE(ousk->oob_skb, skb);
__skb_queue_tail(&other->sk_receive_queue, skb);
spin_unlock(&other->sk_receive_queue.lock);
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;
err = scm_send(sock, msg, &scm, false);
if (err < 0)
return err;
wait_for_unix_gc(scm.fp);
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 = READ_ONCE(sk->sk_state) == TCP_ESTABLISHED ? -EISCONN : -EOPNOTSUPP;
goto out_err;
} else {
err = -ENOTCONN;
other = unix_peer(sk);
if (!other)
goto out_err;
}
if (READ_ONCE(sk->sk_shutdown) & SEND_SHUTDOWN)
goto pipe_err;
while (sent < len) {
size = len - sent;
if (unlikely(msg->msg_flags & MSG_SPLICE_PAGES)) {
skb = sock_alloc_send_pskb(sk, 0, 0,
msg->msg_flags & MSG_DONTWAIT,
&err, 0);
} else {
/* Keep two messages in the pipe so it schedules better */
size = min_t(int, size, (READ_ONCE(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;
if (unlikely(msg->msg_flags & MSG_SPLICE_PAGES)) {
err = skb_splice_from_iter(skb, &msg->msg_iter, size,
sk->sk_allocation);
if (err < 0) {
kfree_skb(skb);
goto out_err;
}
size = err;
refcount_add(size, &sk->sk_wmem_alloc);
} else {
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 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 (READ_ONCE(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 (READ_ONCE(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);
BPF_CGROUP_RUN_PROG_UNIX_RECVMSG_LOCK(sk,
msg->msg_name,
&msg->msg_namelen);
}
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_unix(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);
spin_lock(&sk->sk_receive_queue.lock);
if (sock_flag(sk, SOCK_URGINLINE) || !u->oob_skb) {
spin_unlock(&sk->sk_receive_queue.lock);
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);
spin_unlock(&sk->sk_receive_queue.lock);
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)) {
struct sk_buff *unlinked_skb = NULL;
spin_lock(&sk->sk_receive_queue.lock);
if (copied && (!u->oob_skb || skb == u->oob_skb)) {
skb = NULL;
} else if (flags & MSG_PEEK) {
skb = skb_peek_next(skb, &sk->sk_receive_queue);
} else {
unlinked_skb = skb;
skb = skb_peek_next(skb, &sk->sk_receive_queue);
__skb_unlink(unlinked_skb, &sk->sk_receive_queue);
}
spin_unlock(&sk->sk_receive_queue.lock);
consume_skb(unlinked_skb);
} else {
struct sk_buff *unlinked_skb = NULL;
spin_lock(&sk->sk_receive_queue.lock);
if (skb == u->oob_skb) {
if (copied) {
skb = NULL;
} else if (!(flags & MSG_PEEK)) {
if (sock_flag(sk, SOCK_URGINLINE)) {
WRITE_ONCE(u->oob_skb, NULL);
consume_skb(skb);
} else {
__skb_unlink(skb, &sk->sk_receive_queue);
WRITE_ONCE(u->oob_skb, NULL);
unlinked_skb = skb;
skb = skb_peek(&sk->sk_receive_queue);
}
} else if (!sock_flag(sk, SOCK_URGINLINE)) {
skb = skb_peek_next(skb, &sk->sk_receive_queue);
}
}
spin_unlock(&sk->sk_receive_queue.lock);
if (unlinked_skb) {
WARN_ON_ONCE(skb_unref(unlinked_skb));
kfree_skb(unlinked_skb);
}
}
return skb;
}
#endif
static int unix_stream_read_skb(struct sock *sk, skb_read_actor_t recv_actor)
{
if (unlikely(READ_ONCE(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(READ_ONCE(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 {
struct sk_buff *skb, *last;
int chunk;
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;
again:
#if IS_ENABLED(CONFIG_AF_UNIX_OOB)
if (skb) {
skb = manage_oob(skb, sk, flags, copied);
if (!skb && copied) {
unix_state_unlock(sk);
break;
}
}
#endif
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) ||
test_bit(SOCK_PASSPIDFD, &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);
BPF_CGROUP_RUN_PROG_UNIX_RECVMSG_LOCK(sk,
state->msg->msg_name,
&state->msg->msg_namelen);
sunaddr = NULL;
}
chunk = min_t(unsigned int, unix_skb_len(skb) - skip, size);
chunk = state->recv_actor(skb, skip, chunk, state);
if (chunk < 0) {
if (copied == 0)
copied = -EFAULT;
break;
}
copied += chunk;
size -= chunk;
/* 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_unix(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 (READ_ONCE(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;