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Linux/net/unix/af_unix.c

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  1 /*
  2  * NET4:        Implementation of BSD Unix domain sockets.
  3  *
  4  * Authors:     Alan Cox, <alan@lxorguk.ukuu.org.uk>
  5  *
  6  *              This program is free software; you can redistribute it and/or
  7  *              modify it under the terms of the GNU General Public License
  8  *              as published by the Free Software Foundation; either version
  9  *              2 of the License, or (at your option) any later version.
 10  *
 11  * Fixes:
 12  *              Linus Torvalds  :       Assorted bug cures.
 13  *              Niibe Yutaka    :       async I/O support.
 14  *              Carsten Paeth   :       PF_UNIX check, address fixes.
 15  *              Alan Cox        :       Limit size of allocated blocks.
 16  *              Alan Cox        :       Fixed the stupid socketpair bug.
 17  *              Alan Cox        :       BSD compatibility fine tuning.
 18  *              Alan Cox        :       Fixed a bug in connect when interrupted.
 19  *              Alan Cox        :       Sorted out a proper draft version of
 20  *                                      file descriptor passing hacked up from
 21  *                                      Mike Shaver's work.
 22  *              Marty Leisner   :       Fixes to fd passing
 23  *              Nick Nevin      :       recvmsg bugfix.
 24  *              Alan Cox        :       Started proper garbage collector
 25  *              Heiko EiBfeldt  :       Missing verify_area check
 26  *              Alan Cox        :       Started POSIXisms
 27  *              Andreas Schwab  :       Replace inode by dentry for proper
 28  *                                      reference counting
 29  *              Kirk Petersen   :       Made this a module
 30  *          Christoph Rohland   :       Elegant non-blocking accept/connect algorithm.
 31  *                                      Lots of bug fixes.
 32  *           Alexey Kuznetosv   :       Repaired (I hope) bugs introduces
 33  *                                      by above two patches.
 34  *           Andrea Arcangeli   :       If possible we block in connect(2)
 35  *                                      if the max backlog of the listen socket
 36  *                                      is been reached. This won't break
 37  *                                      old apps and it will avoid huge amount
 38  *                                      of socks hashed (this for unix_gc()
 39  *                                      performances reasons).
 40  *                                      Security fix that limits the max
 41  *                                      number of socks to 2*max_files and
 42  *                                      the number of skb queueable in the
 43  *                                      dgram receiver.
 44  *              Artur Skawina   :       Hash function optimizations
 45  *           Alexey Kuznetsov   :       Full scale SMP. Lot of bugs are introduced 8)
 46  *            Malcolm Beattie   :       Set peercred for socketpair
 47  *           Michal Ostrowski   :       Module initialization cleanup.
 48  *           Arnaldo C. Melo    :       Remove MOD_{INC,DEC}_USE_COUNT,
 49  *                                      the core infrastructure is doing that
 50  *                                      for all net proto families now (2.5.69+)
 51  *
 52  *
 53  * Known differences from reference BSD that was tested:
 54  *
 55  *      [TO FIX]
 56  *      ECONNREFUSED is not returned from one end of a connected() socket to the
 57  *              other the moment one end closes.
 58  *      fstat() doesn't return st_dev=0, and give the blksize as high water mark
 59  *              and a fake inode identifier (nor the BSD first socket fstat twice bug).
 60  *      [NOT TO FIX]
 61  *      accept() returns a path name even if the connecting socket has closed
 62  *              in the meantime (BSD loses the path and gives up).
 63  *      accept() returns 0 length path for an unbound connector. BSD returns 16
 64  *              and a null first byte in the path (but not for gethost/peername - BSD bug ??)
 65  *      socketpair(...SOCK_RAW..) doesn't panic the kernel.
 66  *      BSD af_unix apparently has connect forgetting to block properly.
 67  *              (need to check this with the POSIX spec in detail)
 68  *
 69  * Differences from 2.0.0-11-... (ANK)
 70  *      Bug fixes and improvements.
 71  *              - client shutdown killed server socket.
 72  *              - removed all useless cli/sti pairs.
 73  *
 74  *      Semantic changes/extensions.
 75  *              - generic control message passing.
 76  *              - SCM_CREDENTIALS control message.
 77  *              - "Abstract" (not FS based) socket bindings.
 78  *                Abstract names are sequences of bytes (not zero terminated)
 79  *                started by 0, so that this name space does not intersect
 80  *                with BSD names.
 81  */
 82 
 83 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 84 
 85 #include <linux/module.h>
 86 #include <linux/kernel.h>
 87 #include <linux/signal.h>
 88 #include <linux/sched.h>
 89 #include <linux/errno.h>
 90 #include <linux/string.h>
 91 #include <linux/stat.h>
 92 #include <linux/dcache.h>
 93 #include <linux/namei.h>
 94 #include <linux/socket.h>
 95 #include <linux/un.h>
 96 #include <linux/fcntl.h>
 97 #include <linux/termios.h>
 98 #include <linux/sockios.h>
 99 #include <linux/net.h>
100 #include <linux/in.h>
101 #include <linux/fs.h>
102 #include <linux/slab.h>
103 #include <asm/uaccess.h>
104 #include <linux/skbuff.h>
105 #include <linux/netdevice.h>
106 #include <net/net_namespace.h>
107 #include <net/sock.h>
108 #include <net/tcp_states.h>
109 #include <net/af_unix.h>
110 #include <linux/proc_fs.h>
111 #include <linux/seq_file.h>
112 #include <net/scm.h>
113 #include <linux/init.h>
114 #include <linux/poll.h>
115 #include <linux/rtnetlink.h>
116 #include <linux/mount.h>
117 #include <net/checksum.h>
118 #include <linux/security.h>
119 #include <linux/freezer.h>
120 
121 struct hlist_head unix_socket_table[2 * UNIX_HASH_SIZE];
122 EXPORT_SYMBOL_GPL(unix_socket_table);
123 DEFINE_SPINLOCK(unix_table_lock);
124 EXPORT_SYMBOL_GPL(unix_table_lock);
125 static atomic_long_t unix_nr_socks;
126 
127 
128 static struct hlist_head *unix_sockets_unbound(void *addr)
129 {
130         unsigned long hash = (unsigned long)addr;
131 
132         hash ^= hash >> 16;
133         hash ^= hash >> 8;
134         hash %= UNIX_HASH_SIZE;
135         return &unix_socket_table[UNIX_HASH_SIZE + hash];
136 }
137 
138 #define UNIX_ABSTRACT(sk)       (unix_sk(sk)->addr->hash < UNIX_HASH_SIZE)
139 
140 #ifdef CONFIG_SECURITY_NETWORK
141 static void unix_get_secdata(struct scm_cookie *scm, struct sk_buff *skb)
142 {
143         UNIXCB(skb).secid = scm->secid;
144 }
145 
146 static inline void unix_set_secdata(struct scm_cookie *scm, struct sk_buff *skb)
147 {
148         scm->secid = UNIXCB(skb).secid;
149 }
150 
151 static inline bool unix_secdata_eq(struct scm_cookie *scm, struct sk_buff *skb)
152 {
153         return (scm->secid == UNIXCB(skb).secid);
154 }
155 #else
156 static inline void unix_get_secdata(struct scm_cookie *scm, struct sk_buff *skb)
157 { }
158 
159 static inline void unix_set_secdata(struct scm_cookie *scm, struct sk_buff *skb)
160 { }
161 
162 static inline bool unix_secdata_eq(struct scm_cookie *scm, struct sk_buff *skb)
163 {
164         return true;
165 }
166 #endif /* CONFIG_SECURITY_NETWORK */
167 
168 /*
169  *  SMP locking strategy:
170  *    hash table is protected with spinlock unix_table_lock
171  *    each socket state is protected by separate spin lock.
172  */
173 
174 static inline unsigned int unix_hash_fold(__wsum n)
175 {
176         unsigned int hash = (__force unsigned int)csum_fold(n);
177 
178         hash ^= hash>>8;
179         return hash&(UNIX_HASH_SIZE-1);
180 }
181 
182 #define unix_peer(sk) (unix_sk(sk)->peer)
183 
184 static inline int unix_our_peer(struct sock *sk, struct sock *osk)
185 {
186         return unix_peer(osk) == sk;
187 }
188 
189 static inline int unix_may_send(struct sock *sk, struct sock *osk)
190 {
191         return unix_peer(osk) == NULL || unix_our_peer(sk, osk);
192 }
193 
194 static inline int unix_recvq_full(struct sock const *sk)
195 {
196         return skb_queue_len(&sk->sk_receive_queue) > sk->sk_max_ack_backlog;
197 }
198 
199 struct sock *unix_peer_get(struct sock *s)
200 {
201         struct sock *peer;
202 
203         unix_state_lock(s);
204         peer = unix_peer(s);
205         if (peer)
206                 sock_hold(peer);
207         unix_state_unlock(s);
208         return peer;
209 }
210 EXPORT_SYMBOL_GPL(unix_peer_get);
211 
212 static inline void unix_release_addr(struct unix_address *addr)
213 {
214         if (atomic_dec_and_test(&addr->refcnt))
215                 kfree(addr);
216 }
217 
218 /*
219  *      Check unix socket name:
220  *              - should be not zero length.
221  *              - if started by not zero, should be NULL terminated (FS object)
222  *              - if started by zero, it is abstract name.
223  */
224 
225 static int unix_mkname(struct sockaddr_un *sunaddr, int len, unsigned int *hashp)
226 {
227         if (len <= sizeof(short) || len > sizeof(*sunaddr))
228                 return -EINVAL;
229         if (!sunaddr || sunaddr->sun_family != AF_UNIX)
230                 return -EINVAL;
231         if (sunaddr->sun_path[0]) {
232                 /*
233                  * This may look like an off by one error but it is a bit more
234                  * subtle. 108 is the longest valid AF_UNIX path for a binding.
235                  * sun_path[108] doesn't as such exist.  However in kernel space
236                  * we are guaranteed that it is a valid memory location in our
237                  * kernel address buffer.
238                  */
239                 ((char *)sunaddr)[len] = 0;
240                 len = strlen(sunaddr->sun_path)+1+sizeof(short);
241                 return len;
242         }
243 
244         *hashp = unix_hash_fold(csum_partial(sunaddr, len, 0));
245         return len;
246 }
247 
248 static void __unix_remove_socket(struct sock *sk)
249 {
250         sk_del_node_init(sk);
251 }
252 
253 static void __unix_insert_socket(struct hlist_head *list, struct sock *sk)
254 {
255         WARN_ON(!sk_unhashed(sk));
256         sk_add_node(sk, list);
257 }
258 
259 static inline void unix_remove_socket(struct sock *sk)
260 {
261         spin_lock(&unix_table_lock);
262         __unix_remove_socket(sk);
263         spin_unlock(&unix_table_lock);
264 }
265 
266 static inline void unix_insert_socket(struct hlist_head *list, struct sock *sk)
267 {
268         spin_lock(&unix_table_lock);
269         __unix_insert_socket(list, sk);
270         spin_unlock(&unix_table_lock);
271 }
272 
273 static struct sock *__unix_find_socket_byname(struct net *net,
274                                               struct sockaddr_un *sunname,
275                                               int len, int type, unsigned int hash)
276 {
277         struct sock *s;
278 
279         sk_for_each(s, &unix_socket_table[hash ^ type]) {
280                 struct unix_sock *u = unix_sk(s);
281 
282                 if (!net_eq(sock_net(s), net))
283                         continue;
284 
285                 if (u->addr->len == len &&
286                     !memcmp(u->addr->name, sunname, len))
287                         goto found;
288         }
289         s = NULL;
290 found:
291         return s;
292 }
293 
294 static inline struct sock *unix_find_socket_byname(struct net *net,
295                                                    struct sockaddr_un *sunname,
296                                                    int len, int type,
297                                                    unsigned int hash)
298 {
299         struct sock *s;
300 
301         spin_lock(&unix_table_lock);
302         s = __unix_find_socket_byname(net, sunname, len, type, hash);
303         if (s)
304                 sock_hold(s);
305         spin_unlock(&unix_table_lock);
306         return s;
307 }
308 
309 static struct sock *unix_find_socket_byinode(struct inode *i)
310 {
311         struct sock *s;
312 
313         spin_lock(&unix_table_lock);
314         sk_for_each(s,
315                     &unix_socket_table[i->i_ino & (UNIX_HASH_SIZE - 1)]) {
316                 struct dentry *dentry = unix_sk(s)->path.dentry;
317 
318                 if (dentry && d_backing_inode(dentry) == i) {
319                         sock_hold(s);
320                         goto found;
321                 }
322         }
323         s = NULL;
324 found:
325         spin_unlock(&unix_table_lock);
326         return s;
327 }
328 
329 /* Support code for asymmetrically connected dgram sockets
330  *
331  * If a datagram socket is connected to a socket not itself connected
332  * to the first socket (eg, /dev/log), clients may only enqueue more
333  * messages if the present receive queue of the server socket is not
334  * "too large". This means there's a second writeability condition
335  * poll and sendmsg need to test. The dgram recv code will do a wake
336  * up on the peer_wait wait queue of a socket upon reception of a
337  * datagram which needs to be propagated to sleeping would-be writers
338  * since these might not have sent anything so far. This can't be
339  * accomplished via poll_wait because the lifetime of the server
340  * socket might be less than that of its clients if these break their
341  * association with it or if the server socket is closed while clients
342  * are still connected to it and there's no way to inform "a polling
343  * implementation" that it should let go of a certain wait queue
344  *
345  * In order to propagate a wake up, a wait_queue_t of the client
346  * socket is enqueued on the peer_wait queue of the server socket
347  * whose wake function does a wake_up on the ordinary client socket
348  * wait queue. This connection is established whenever a write (or
349  * poll for write) hit the flow control condition and broken when the
350  * association to the server socket is dissolved or after a wake up
351  * was relayed.
352  */
353 
354 static int unix_dgram_peer_wake_relay(wait_queue_t *q, unsigned mode, int flags,
355                                       void *key)
356 {
357         struct unix_sock *u;
358         wait_queue_head_t *u_sleep;
359 
360         u = container_of(q, struct unix_sock, peer_wake);
361 
362         __remove_wait_queue(&unix_sk(u->peer_wake.private)->peer_wait,
363                             q);
364         u->peer_wake.private = NULL;
365 
366         /* relaying can only happen while the wq still exists */
367         u_sleep = sk_sleep(&u->sk);
368         if (u_sleep)
369                 wake_up_interruptible_poll(u_sleep, key);
370 
371         return 0;
372 }
373 
374 static int unix_dgram_peer_wake_connect(struct sock *sk, struct sock *other)
375 {
376         struct unix_sock *u, *u_other;
377         int rc;
378 
379         u = unix_sk(sk);
380         u_other = unix_sk(other);
381         rc = 0;
382         spin_lock(&u_other->peer_wait.lock);
383 
384         if (!u->peer_wake.private) {
385                 u->peer_wake.private = other;
386                 __add_wait_queue(&u_other->peer_wait, &u->peer_wake);
387 
388                 rc = 1;
389         }
390 
391         spin_unlock(&u_other->peer_wait.lock);
392         return rc;
393 }
394 
395 static void unix_dgram_peer_wake_disconnect(struct sock *sk,
396                                             struct sock *other)
397 {
398         struct unix_sock *u, *u_other;
399 
400         u = unix_sk(sk);
401         u_other = unix_sk(other);
402         spin_lock(&u_other->peer_wait.lock);
403 
404         if (u->peer_wake.private == other) {
405                 __remove_wait_queue(&u_other->peer_wait, &u->peer_wake);
406                 u->peer_wake.private = NULL;
407         }
408 
409         spin_unlock(&u_other->peer_wait.lock);
410 }
411 
412 static void unix_dgram_peer_wake_disconnect_wakeup(struct sock *sk,
413                                                    struct sock *other)
414 {
415         unix_dgram_peer_wake_disconnect(sk, other);
416         wake_up_interruptible_poll(sk_sleep(sk),
417                                    POLLOUT |
418                                    POLLWRNORM |
419                                    POLLWRBAND);
420 }
421 
422 /* preconditions:
423  *      - unix_peer(sk) == other
424  *      - association is stable
425  */
426 static int unix_dgram_peer_wake_me(struct sock *sk, struct sock *other)
427 {
428         int connected;
429 
430         connected = unix_dgram_peer_wake_connect(sk, other);
431 
432         if (unix_recvq_full(other))
433                 return 1;
434 
435         if (connected)
436                 unix_dgram_peer_wake_disconnect(sk, other);
437 
438         return 0;
439 }
440 
441 static int unix_writable(const struct sock *sk)
442 {
443         return sk->sk_state != TCP_LISTEN &&
444                (atomic_read(&sk->sk_wmem_alloc) << 2) <= sk->sk_sndbuf;
445 }
446 
447 static void unix_write_space(struct sock *sk)
448 {
449         struct socket_wq *wq;
450 
451         rcu_read_lock();
452         if (unix_writable(sk)) {
453                 wq = rcu_dereference(sk->sk_wq);
454                 if (skwq_has_sleeper(wq))
455                         wake_up_interruptible_sync_poll(&wq->wait,
456                                 POLLOUT | POLLWRNORM | POLLWRBAND);
457                 sk_wake_async(sk, SOCK_WAKE_SPACE, POLL_OUT);
458         }
459         rcu_read_unlock();
460 }
461 
462 /* When dgram socket disconnects (or changes its peer), we clear its receive
463  * queue of packets arrived from previous peer. First, it allows to do
464  * flow control based only on wmem_alloc; second, sk connected to peer
465  * may receive messages only from that peer. */
466 static void unix_dgram_disconnected(struct sock *sk, struct sock *other)
467 {
468         if (!skb_queue_empty(&sk->sk_receive_queue)) {
469                 skb_queue_purge(&sk->sk_receive_queue);
470                 wake_up_interruptible_all(&unix_sk(sk)->peer_wait);
471 
472                 /* If one link of bidirectional dgram pipe is disconnected,
473                  * we signal error. Messages are lost. Do not make this,
474                  * when peer was not connected to us.
475                  */
476                 if (!sock_flag(other, SOCK_DEAD) && unix_peer(other) == sk) {
477                         other->sk_err = ECONNRESET;
478                         other->sk_error_report(other);
479                 }
480         }
481 }
482 
483 static void unix_sock_destructor(struct sock *sk)
484 {
485         struct unix_sock *u = unix_sk(sk);
486 
487         skb_queue_purge(&sk->sk_receive_queue);
488 
489         WARN_ON(atomic_read(&sk->sk_wmem_alloc));
490         WARN_ON(!sk_unhashed(sk));
491         WARN_ON(sk->sk_socket);
492         if (!sock_flag(sk, SOCK_DEAD)) {
493                 pr_info("Attempt to release alive unix socket: %p\n", sk);
494                 return;
495         }
496 
497         if (u->addr)
498                 unix_release_addr(u->addr);
499 
500         atomic_long_dec(&unix_nr_socks);
501         local_bh_disable();
502         sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
503         local_bh_enable();
504 #ifdef UNIX_REFCNT_DEBUG
505         pr_debug("UNIX %p is destroyed, %ld are still alive.\n", sk,
506                 atomic_long_read(&unix_nr_socks));
507 #endif
508 }
509 
510 static void unix_release_sock(struct sock *sk, int embrion)
511 {
512         struct unix_sock *u = unix_sk(sk);
513         struct path path;
514         struct sock *skpair;
515         struct sk_buff *skb;
516         int state;
517 
518         unix_remove_socket(sk);
519 
520         /* Clear state */
521         unix_state_lock(sk);
522         sock_orphan(sk);
523         sk->sk_shutdown = SHUTDOWN_MASK;
524         path         = u->path;
525         u->path.dentry = NULL;
526         u->path.mnt = NULL;
527         state = sk->sk_state;
528         sk->sk_state = TCP_CLOSE;
529         unix_state_unlock(sk);
530 
531         wake_up_interruptible_all(&u->peer_wait);
532 
533         skpair = unix_peer(sk);
534 
535         if (skpair != NULL) {
536                 if (sk->sk_type == SOCK_STREAM || sk->sk_type == SOCK_SEQPACKET) {
537                         unix_state_lock(skpair);
538                         /* No more writes */
539                         skpair->sk_shutdown = SHUTDOWN_MASK;
540                         if (!skb_queue_empty(&sk->sk_receive_queue) || embrion)
541                                 skpair->sk_err = ECONNRESET;
542                         unix_state_unlock(skpair);
543                         skpair->sk_state_change(skpair);
544                         sk_wake_async(skpair, SOCK_WAKE_WAITD, POLL_HUP);
545                 }
546 
547                 unix_dgram_peer_wake_disconnect(sk, skpair);
548                 sock_put(skpair); /* It may now die */
549                 unix_peer(sk) = NULL;
550         }
551 
552         /* Try to flush out this socket. Throw out buffers at least */
553 
554         while ((skb = skb_dequeue(&sk->sk_receive_queue)) != NULL) {
555                 if (state == TCP_LISTEN)
556                         unix_release_sock(skb->sk, 1);
557                 /* passed fds are erased in the kfree_skb hook        */
558                 UNIXCB(skb).consumed = skb->len;
559                 kfree_skb(skb);
560         }
561 
562         if (path.dentry)
563                 path_put(&path);
564 
565         sock_put(sk);
566 
567         /* ---- Socket is dead now and most probably destroyed ---- */
568 
569         /*
570          * Fixme: BSD difference: In BSD all sockets connected to us get
571          *        ECONNRESET and we die on the spot. In Linux we behave
572          *        like files and pipes do and wait for the last
573          *        dereference.
574          *
575          * Can't we simply set sock->err?
576          *
577          *        What the above comment does talk about? --ANK(980817)
578          */
579 
580         if (unix_tot_inflight)
581                 unix_gc();              /* Garbage collect fds */
582 }
583 
584 static void init_peercred(struct sock *sk)
585 {
586         put_pid(sk->sk_peer_pid);
587         if (sk->sk_peer_cred)
588                 put_cred(sk->sk_peer_cred);
589         sk->sk_peer_pid  = get_pid(task_tgid(current));
590         sk->sk_peer_cred = get_current_cred();
591 }
592 
593 static void copy_peercred(struct sock *sk, struct sock *peersk)
594 {
595         put_pid(sk->sk_peer_pid);
596         if (sk->sk_peer_cred)
597                 put_cred(sk->sk_peer_cred);
598         sk->sk_peer_pid  = get_pid(peersk->sk_peer_pid);
599         sk->sk_peer_cred = get_cred(peersk->sk_peer_cred);
600 }
601 
602 static int unix_listen(struct socket *sock, int backlog)
603 {
604         int err;
605         struct sock *sk = sock->sk;
606         struct unix_sock *u = unix_sk(sk);
607         struct pid *old_pid = NULL;
608 
609         err = -EOPNOTSUPP;
610         if (sock->type != SOCK_STREAM && sock->type != SOCK_SEQPACKET)
611                 goto out;       /* Only stream/seqpacket sockets accept */
612         err = -EINVAL;
613         if (!u->addr)
614                 goto out;       /* No listens on an unbound socket */
615         unix_state_lock(sk);
616         if (sk->sk_state != TCP_CLOSE && sk->sk_state != TCP_LISTEN)
617                 goto out_unlock;
618         if (backlog > sk->sk_max_ack_backlog)
619                 wake_up_interruptible_all(&u->peer_wait);
620         sk->sk_max_ack_backlog  = backlog;
621         sk->sk_state            = TCP_LISTEN;
622         /* set credentials so connect can copy them */
623         init_peercred(sk);
624         err = 0;
625 
626 out_unlock:
627         unix_state_unlock(sk);
628         put_pid(old_pid);
629 out:
630         return err;
631 }
632 
633 static int unix_release(struct socket *);
634 static int unix_bind(struct socket *, struct sockaddr *, int);
635 static int unix_stream_connect(struct socket *, struct sockaddr *,
636                                int addr_len, int flags);
637 static int unix_socketpair(struct socket *, struct socket *);
638 static int unix_accept(struct socket *, struct socket *, int);
639 static int unix_getname(struct socket *, struct sockaddr *, int *, int);
640 static unsigned int unix_poll(struct file *, struct socket *, poll_table *);
641 static unsigned int unix_dgram_poll(struct file *, struct socket *,
642                                     poll_table *);
643 static int unix_ioctl(struct socket *, unsigned int, unsigned long);
644 static int unix_shutdown(struct socket *, int);
645 static int unix_stream_sendmsg(struct socket *, struct msghdr *, size_t);
646 static int unix_stream_recvmsg(struct socket *, struct msghdr *, size_t, int);
647 static ssize_t unix_stream_sendpage(struct socket *, struct page *, int offset,
648                                     size_t size, int flags);
649 static ssize_t unix_stream_splice_read(struct socket *,  loff_t *ppos,
650                                        struct pipe_inode_info *, size_t size,
651                                        unsigned int flags);
652 static int unix_dgram_sendmsg(struct socket *, struct msghdr *, size_t);
653 static int unix_dgram_recvmsg(struct socket *, struct msghdr *, size_t, int);
654 static int unix_dgram_connect(struct socket *, struct sockaddr *,
655                               int, int);
656 static int unix_seqpacket_sendmsg(struct socket *, struct msghdr *, size_t);
657 static int unix_seqpacket_recvmsg(struct socket *, struct msghdr *, size_t,
658                                   int);
659 
660 static int unix_set_peek_off(struct sock *sk, int val)
661 {
662         struct unix_sock *u = unix_sk(sk);
663 
664         if (mutex_lock_interruptible(&u->readlock))
665                 return -EINTR;
666 
667         sk->sk_peek_off = val;
668         mutex_unlock(&u->readlock);
669 
670         return 0;
671 }
672 
673 
674 static const struct proto_ops unix_stream_ops = {
675         .family =       PF_UNIX,
676         .owner =        THIS_MODULE,
677         .release =      unix_release,
678         .bind =         unix_bind,
679         .connect =      unix_stream_connect,
680         .socketpair =   unix_socketpair,
681         .accept =       unix_accept,
682         .getname =      unix_getname,
683         .poll =         unix_poll,
684         .ioctl =        unix_ioctl,
685         .listen =       unix_listen,
686         .shutdown =     unix_shutdown,
687         .setsockopt =   sock_no_setsockopt,
688         .getsockopt =   sock_no_getsockopt,
689         .sendmsg =      unix_stream_sendmsg,
690         .recvmsg =      unix_stream_recvmsg,
691         .mmap =         sock_no_mmap,
692         .sendpage =     unix_stream_sendpage,
693         .splice_read =  unix_stream_splice_read,
694         .set_peek_off = unix_set_peek_off,
695 };
696 
697 static const struct proto_ops unix_dgram_ops = {
698         .family =       PF_UNIX,
699         .owner =        THIS_MODULE,
700         .release =      unix_release,
701         .bind =         unix_bind,
702         .connect =      unix_dgram_connect,
703         .socketpair =   unix_socketpair,
704         .accept =       sock_no_accept,
705         .getname =      unix_getname,
706         .poll =         unix_dgram_poll,
707         .ioctl =        unix_ioctl,
708         .listen =       sock_no_listen,
709         .shutdown =     unix_shutdown,
710         .setsockopt =   sock_no_setsockopt,
711         .getsockopt =   sock_no_getsockopt,
712         .sendmsg =      unix_dgram_sendmsg,
713         .recvmsg =      unix_dgram_recvmsg,
714         .mmap =         sock_no_mmap,
715         .sendpage =     sock_no_sendpage,
716         .set_peek_off = unix_set_peek_off,
717 };
718 
719 static const struct proto_ops unix_seqpacket_ops = {
720         .family =       PF_UNIX,
721         .owner =        THIS_MODULE,
722         .release =      unix_release,
723         .bind =         unix_bind,
724         .connect =      unix_stream_connect,
725         .socketpair =   unix_socketpair,
726         .accept =       unix_accept,
727         .getname =      unix_getname,
728         .poll =         unix_dgram_poll,
729         .ioctl =        unix_ioctl,
730         .listen =       unix_listen,
731         .shutdown =     unix_shutdown,
732         .setsockopt =   sock_no_setsockopt,
733         .getsockopt =   sock_no_getsockopt,
734         .sendmsg =      unix_seqpacket_sendmsg,
735         .recvmsg =      unix_seqpacket_recvmsg,
736         .mmap =         sock_no_mmap,
737         .sendpage =     sock_no_sendpage,
738         .set_peek_off = unix_set_peek_off,
739 };
740 
741 static struct proto unix_proto = {
742         .name                   = "UNIX",
743         .owner                  = THIS_MODULE,
744         .obj_size               = sizeof(struct unix_sock),
745 };
746 
747 /*
748  * AF_UNIX sockets do not interact with hardware, hence they
749  * dont trigger interrupts - so it's safe for them to have
750  * bh-unsafe locking for their sk_receive_queue.lock. Split off
751  * this special lock-class by reinitializing the spinlock key:
752  */
753 static struct lock_class_key af_unix_sk_receive_queue_lock_key;
754 
755 static struct sock *unix_create1(struct net *net, struct socket *sock, int kern)
756 {
757         struct sock *sk = NULL;
758         struct unix_sock *u;
759 
760         atomic_long_inc(&unix_nr_socks);
761         if (atomic_long_read(&unix_nr_socks) > 2 * get_max_files())
762                 goto out;
763 
764         sk = sk_alloc(net, PF_UNIX, GFP_KERNEL, &unix_proto, kern);
765         if (!sk)
766                 goto out;
767 
768         sock_init_data(sock, sk);
769         lockdep_set_class(&sk->sk_receive_queue.lock,
770                                 &af_unix_sk_receive_queue_lock_key);
771 
772         sk->sk_write_space      = unix_write_space;
773         sk->sk_max_ack_backlog  = net->unx.sysctl_max_dgram_qlen;
774         sk->sk_destruct         = unix_sock_destructor;
775         u         = unix_sk(sk);
776         u->path.dentry = NULL;
777         u->path.mnt = NULL;
778         spin_lock_init(&u->lock);
779         atomic_long_set(&u->inflight, 0);
780         INIT_LIST_HEAD(&u->link);
781         mutex_init(&u->readlock); /* single task reading lock */
782         init_waitqueue_head(&u->peer_wait);
783         init_waitqueue_func_entry(&u->peer_wake, unix_dgram_peer_wake_relay);
784         unix_insert_socket(unix_sockets_unbound(sk), sk);
785 out:
786         if (sk == NULL)
787                 atomic_long_dec(&unix_nr_socks);
788         else {
789                 local_bh_disable();
790                 sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
791                 local_bh_enable();
792         }
793         return sk;
794 }
795 
796 static int unix_create(struct net *net, struct socket *sock, int protocol,
797                        int kern)
798 {
799         if (protocol && protocol != PF_UNIX)
800                 return -EPROTONOSUPPORT;
801 
802         sock->state = SS_UNCONNECTED;
803 
804         switch (sock->type) {
805         case SOCK_STREAM:
806                 sock->ops = &unix_stream_ops;
807                 break;
808                 /*
809                  *      Believe it or not BSD has AF_UNIX, SOCK_RAW though
810                  *      nothing uses it.
811                  */
812         case SOCK_RAW:
813                 sock->type = SOCK_DGRAM;
814         case SOCK_DGRAM:
815                 sock->ops = &unix_dgram_ops;
816                 break;
817         case SOCK_SEQPACKET:
818                 sock->ops = &unix_seqpacket_ops;
819                 break;
820         default:
821                 return -ESOCKTNOSUPPORT;
822         }
823 
824         return unix_create1(net, sock, kern) ? 0 : -ENOMEM;
825 }
826 
827 static int unix_release(struct socket *sock)
828 {
829         struct sock *sk = sock->sk;
830 
831         if (!sk)
832                 return 0;
833 
834         unix_release_sock(sk, 0);
835         sock->sk = NULL;
836 
837         return 0;
838 }
839 
840 static int unix_autobind(struct socket *sock)
841 {
842         struct sock *sk = sock->sk;
843         struct net *net = sock_net(sk);
844         struct unix_sock *u = unix_sk(sk);
845         static u32 ordernum = 1;
846         struct unix_address *addr;
847         int err;
848         unsigned int retries = 0;
849 
850         err = mutex_lock_interruptible(&u->readlock);
851         if (err)
852                 return err;
853 
854         err = 0;
855         if (u->addr)
856                 goto out;
857 
858         err = -ENOMEM;
859         addr = kzalloc(sizeof(*addr) + sizeof(short) + 16, GFP_KERNEL);
860         if (!addr)
861                 goto out;
862 
863         addr->name->sun_family = AF_UNIX;
864         atomic_set(&addr->refcnt, 1);
865 
866 retry:
867         addr->len = sprintf(addr->name->sun_path+1, "%05x", ordernum) + 1 + sizeof(short);
868         addr->hash = unix_hash_fold(csum_partial(addr->name, addr->len, 0));
869 
870         spin_lock(&unix_table_lock);
871         ordernum = (ordernum+1)&0xFFFFF;
872 
873         if (__unix_find_socket_byname(net, addr->name, addr->len, sock->type,
874                                       addr->hash)) {
875                 spin_unlock(&unix_table_lock);
876                 /*
877                  * __unix_find_socket_byname() may take long time if many names
878                  * are already in use.
879                  */
880                 cond_resched();
881                 /* Give up if all names seems to be in use. */
882                 if (retries++ == 0xFFFFF) {
883                         err = -ENOSPC;
884                         kfree(addr);
885                         goto out;
886                 }
887                 goto retry;
888         }
889         addr->hash ^= sk->sk_type;
890 
891         __unix_remove_socket(sk);
892         u->addr = addr;
893         __unix_insert_socket(&unix_socket_table[addr->hash], sk);
894         spin_unlock(&unix_table_lock);
895         err = 0;
896 
897 out:    mutex_unlock(&u->readlock);
898         return err;
899 }
900 
901 static struct sock *unix_find_other(struct net *net,
902                                     struct sockaddr_un *sunname, int len,
903                                     int type, unsigned int hash, int *error)
904 {
905         struct sock *u;
906         struct path path;
907         int err = 0;
908 
909         if (sunname->sun_path[0]) {
910                 struct inode *inode;
911                 err = kern_path(sunname->sun_path, LOOKUP_FOLLOW, &path);
912                 if (err)
913                         goto fail;
914                 inode = d_backing_inode(path.dentry);
915                 err = inode_permission(inode, MAY_WRITE);
916                 if (err)
917                         goto put_fail;
918 
919                 err = -ECONNREFUSED;
920                 if (!S_ISSOCK(inode->i_mode))
921                         goto put_fail;
922                 u = unix_find_socket_byinode(inode);
923                 if (!u)
924                         goto put_fail;
925 
926                 if (u->sk_type == type)
927                         touch_atime(&path);
928 
929                 path_put(&path);
930 
931                 err = -EPROTOTYPE;
932                 if (u->sk_type != type) {
933                         sock_put(u);
934                         goto fail;
935                 }
936         } else {
937                 err = -ECONNREFUSED;
938                 u = unix_find_socket_byname(net, sunname, len, type, hash);
939                 if (u) {
940                         struct dentry *dentry;
941                         dentry = unix_sk(u)->path.dentry;
942                         if (dentry)
943                                 touch_atime(&unix_sk(u)->path);
944                 } else
945                         goto fail;
946         }
947         return u;
948 
949 put_fail:
950         path_put(&path);
951 fail:
952         *error = err;
953         return NULL;
954 }
955 
956 static int unix_mknod(struct dentry *dentry, struct path *path, umode_t mode,
957                       struct path *res)
958 {
959         int err;
960 
961         err = security_path_mknod(path, dentry, mode, 0);
962         if (!err) {
963                 err = vfs_mknod(d_inode(path->dentry), dentry, mode, 0);
964                 if (!err) {
965                         res->mnt = mntget(path->mnt);
966                         res->dentry = dget(dentry);
967                 }
968         }
969 
970         return err;
971 }
972 
973 static int unix_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
974 {
975         struct sock *sk = sock->sk;
976         struct net *net = sock_net(sk);
977         struct unix_sock *u = unix_sk(sk);
978         struct sockaddr_un *sunaddr = (struct sockaddr_un *)uaddr;
979         char *sun_path = sunaddr->sun_path;
980         int err, name_err;
981         unsigned int hash;
982         struct unix_address *addr;
983         struct hlist_head *list;
984         struct path path;
985         struct dentry *dentry;
986 
987         err = -EINVAL;
988         if (sunaddr->sun_family != AF_UNIX)
989                 goto out;
990 
991         if (addr_len == sizeof(short)) {
992                 err = unix_autobind(sock);
993                 goto out;
994         }
995 
996         err = unix_mkname(sunaddr, addr_len, &hash);
997         if (err < 0)
998                 goto out;
999         addr_len = err;
1000 
1001         name_err = 0;
1002         dentry = NULL;
1003         if (sun_path[0]) {
1004                 /* Get the parent directory, calculate the hash for last
1005                  * component.
1006                  */
1007                 dentry = kern_path_create(AT_FDCWD, sun_path, &path, 0);
1008 
1009                 if (IS_ERR(dentry)) {
1010                         /* delay report until after 'already bound' check */
1011                         name_err = PTR_ERR(dentry);
1012                         dentry = NULL;
1013                 }
1014         }
1015 
1016         err = mutex_lock_interruptible(&u->readlock);
1017         if (err)
1018                 goto out_path;
1019 
1020         err = -EINVAL;
1021         if (u->addr)
1022                 goto out_up;
1023 
1024         if (name_err) {
1025                 err = name_err == -EEXIST ? -EADDRINUSE : name_err;
1026                 goto out_up;
1027         }
1028 
1029         err = -ENOMEM;
1030         addr = kmalloc(sizeof(*addr)+addr_len, GFP_KERNEL);
1031         if (!addr)
1032                 goto out_up;
1033 
1034         memcpy(addr->name, sunaddr, addr_len);
1035         addr->len = addr_len;
1036         addr->hash = hash ^ sk->sk_type;
1037         atomic_set(&addr->refcnt, 1);
1038 
1039         if (dentry) {
1040                 struct path u_path;
1041                 umode_t mode = S_IFSOCK |
1042                        (SOCK_INODE(sock)->i_mode & ~current_umask());
1043                 err = unix_mknod(dentry, &path, mode, &u_path);
1044                 if (err) {
1045                         if (err == -EEXIST)
1046                                 err = -EADDRINUSE;
1047                         unix_release_addr(addr);
1048                         goto out_up;
1049                 }
1050                 addr->hash = UNIX_HASH_SIZE;
1051                 hash = d_backing_inode(dentry)->i_ino & (UNIX_HASH_SIZE - 1);
1052                 spin_lock(&unix_table_lock);
1053                 u->path = u_path;
1054                 list = &unix_socket_table[hash];
1055         } else {
1056                 spin_lock(&unix_table_lock);
1057                 err = -EADDRINUSE;
1058                 if (__unix_find_socket_byname(net, sunaddr, addr_len,
1059                                               sk->sk_type, hash)) {
1060                         unix_release_addr(addr);
1061                         goto out_unlock;
1062                 }
1063 
1064                 list = &unix_socket_table[addr->hash];
1065         }
1066 
1067         err = 0;
1068         __unix_remove_socket(sk);
1069         u->addr = addr;
1070         __unix_insert_socket(list, sk);
1071 
1072 out_unlock:
1073         spin_unlock(&unix_table_lock);
1074 out_up:
1075         mutex_unlock(&u->readlock);
1076 out_path:
1077         if (dentry)
1078                 done_path_create(&path, dentry);
1079 
1080 out:
1081         return err;
1082 }
1083 
1084 static void unix_state_double_lock(struct sock *sk1, struct sock *sk2)
1085 {
1086         if (unlikely(sk1 == sk2) || !sk2) {
1087                 unix_state_lock(sk1);
1088                 return;
1089         }
1090         if (sk1 < sk2) {
1091                 unix_state_lock(sk1);
1092                 unix_state_lock_nested(sk2);
1093         } else {
1094                 unix_state_lock(sk2);
1095                 unix_state_lock_nested(sk1);
1096         }
1097 }
1098 
1099 static void unix_state_double_unlock(struct sock *sk1, struct sock *sk2)
1100 {
1101         if (unlikely(sk1 == sk2) || !sk2) {
1102                 unix_state_unlock(sk1);
1103                 return;
1104         }
1105         unix_state_unlock(sk1);
1106         unix_state_unlock(sk2);
1107 }
1108 
1109 static int unix_dgram_connect(struct socket *sock, struct sockaddr *addr,
1110                               int alen, int flags)
1111 {
1112         struct sock *sk = sock->sk;
1113         struct net *net = sock_net(sk);
1114         struct sockaddr_un *sunaddr = (struct sockaddr_un *)addr;
1115         struct sock *other;
1116         unsigned int hash;
1117         int err;
1118 
1119         if (addr->sa_family != AF_UNSPEC) {
1120                 err = unix_mkname(sunaddr, alen, &hash);
1121                 if (err < 0)
1122                         goto out;
1123                 alen = err;
1124 
1125                 if (test_bit(SOCK_PASSCRED, &sock->flags) &&
1126                     !unix_sk(sk)->addr && (err = unix_autobind(sock)) != 0)
1127                         goto out;
1128 
1129 restart:
1130                 other = unix_find_other(net, sunaddr, alen, sock->type, hash, &err);
1131                 if (!other)
1132                         goto out;
1133 
1134                 unix_state_double_lock(sk, other);
1135 
1136                 /* Apparently VFS overslept socket death. Retry. */
1137                 if (sock_flag(other, SOCK_DEAD)) {
1138                         unix_state_double_unlock(sk, other);
1139                         sock_put(other);
1140                         goto restart;
1141                 }
1142 
1143                 err = -EPERM;
1144                 if (!unix_may_send(sk, other))
1145                         goto out_unlock;
1146 
1147                 err = security_unix_may_send(sk->sk_socket, other->sk_socket);
1148                 if (err)
1149                         goto out_unlock;
1150 
1151         } else {
1152                 /*
1153                  *      1003.1g breaking connected state with AF_UNSPEC
1154                  */
1155                 other = NULL;
1156                 unix_state_double_lock(sk, other);
1157         }
1158 
1159         /*
1160          * If it was connected, reconnect.
1161          */
1162         if (unix_peer(sk)) {
1163                 struct sock *old_peer = unix_peer(sk);
1164                 unix_peer(sk) = other;
1165                 unix_dgram_peer_wake_disconnect_wakeup(sk, old_peer);
1166 
1167                 unix_state_double_unlock(sk, other);
1168 
1169                 if (other != old_peer)
1170                         unix_dgram_disconnected(sk, old_peer);
1171                 sock_put(old_peer);
1172         } else {
1173                 unix_peer(sk) = other;
1174                 unix_state_double_unlock(sk, other);
1175         }
1176         return 0;
1177 
1178 out_unlock:
1179         unix_state_double_unlock(sk, other);
1180         sock_put(other);
1181 out:
1182         return err;
1183 }
1184 
1185 static long unix_wait_for_peer(struct sock *other, long timeo)
1186 {
1187         struct unix_sock *u = unix_sk(other);
1188         int sched;
1189         DEFINE_WAIT(wait);
1190 
1191         prepare_to_wait_exclusive(&u->peer_wait, &wait, TASK_INTERRUPTIBLE);
1192 
1193         sched = !sock_flag(other, SOCK_DEAD) &&
1194                 !(other->sk_shutdown & RCV_SHUTDOWN) &&
1195                 unix_recvq_full(other);
1196 
1197         unix_state_unlock(other);
1198 
1199         if (sched)
1200                 timeo = schedule_timeout(timeo);
1201 
1202         finish_wait(&u->peer_wait, &wait);
1203         return timeo;
1204 }
1205 
1206 static int unix_stream_connect(struct socket *sock, struct sockaddr *uaddr,
1207                                int addr_len, int flags)
1208 {
1209         struct sockaddr_un *sunaddr = (struct sockaddr_un *)uaddr;
1210         struct sock *sk = sock->sk;
1211         struct net *net = sock_net(sk);
1212         struct unix_sock *u = unix_sk(sk), *newu, *otheru;
1213         struct sock *newsk = NULL;
1214         struct sock *other = NULL;
1215         struct sk_buff *skb = NULL;
1216         unsigned int hash;
1217         int st;
1218         int err;
1219         long timeo;
1220 
1221         err = unix_mkname(sunaddr, addr_len, &hash);
1222         if (err < 0)
1223                 goto out;
1224         addr_len = err;
1225 
1226         if (test_bit(SOCK_PASSCRED, &sock->flags) && !u->addr &&
1227             (err = unix_autobind(sock)) != 0)
1228                 goto out;
1229 
1230         timeo = sock_sndtimeo(sk, flags & O_NONBLOCK);
1231 
1232         /* First of all allocate resources.
1233            If we will make it after state is locked,
1234            we will have to recheck all again in any case.
1235          */
1236 
1237         err = -ENOMEM;
1238 
1239         /* create new sock for complete connection */
1240         newsk = unix_create1(sock_net(sk), NULL, 0);
1241         if (newsk == NULL)
1242                 goto out;
1243 
1244         /* Allocate skb for sending to listening sock */
1245         skb = sock_wmalloc(newsk, 1, 0, GFP_KERNEL);
1246         if (skb == NULL)
1247                 goto out;
1248 
1249 restart:
1250         /*  Find listening sock. */
1251         other = unix_find_other(net, sunaddr, addr_len, sk->sk_type, hash, &err);
1252         if (!other)
1253                 goto out;
1254 
1255         /* Latch state of peer */
1256         unix_state_lock(other);
1257 
1258         /* Apparently VFS overslept socket death. Retry. */
1259         if (sock_flag(other, SOCK_DEAD)) {
1260                 unix_state_unlock(other);
1261                 sock_put(other);
1262                 goto restart;
1263         }
1264 
1265         err = -ECONNREFUSED;
1266         if (other->sk_state != TCP_LISTEN)
1267                 goto out_unlock;
1268         if (other->sk_shutdown & RCV_SHUTDOWN)
1269                 goto out_unlock;
1270 
1271         if (unix_recvq_full(other)) {
1272                 err = -EAGAIN;
1273                 if (!timeo)
1274                         goto out_unlock;
1275 
1276                 timeo = unix_wait_for_peer(other, timeo);
1277 
1278                 err = sock_intr_errno(timeo);
1279                 if (signal_pending(current))
1280                         goto out;
1281                 sock_put(other);
1282                 goto restart;
1283         }
1284 
1285         /* Latch our state.
1286 
1287            It is tricky place. We need to grab our state lock and cannot
1288            drop lock on peer. It is dangerous because deadlock is
1289            possible. Connect to self case and simultaneous
1290            attempt to connect are eliminated by checking socket
1291            state. other is TCP_LISTEN, if sk is TCP_LISTEN we
1292            check this before attempt to grab lock.
1293 
1294            Well, and we have to recheck the state after socket locked.
1295          */
1296         st = sk->sk_state;
1297 
1298         switch (st) {
1299         case TCP_CLOSE:
1300                 /* This is ok... continue with connect */
1301                 break;
1302         case TCP_ESTABLISHED:
1303                 /* Socket is already connected */
1304                 err = -EISCONN;
1305                 goto out_unlock;
1306         default:
1307                 err = -EINVAL;
1308                 goto out_unlock;
1309         }
1310 
1311         unix_state_lock_nested(sk);
1312 
1313         if (sk->sk_state != st) {
1314                 unix_state_unlock(sk);
1315                 unix_state_unlock(other);
1316                 sock_put(other);
1317                 goto restart;
1318         }
1319 
1320         err = security_unix_stream_connect(sk, other, newsk);
1321         if (err) {
1322                 unix_state_unlock(sk);
1323                 goto out_unlock;
1324         }
1325 
1326         /* The way is open! Fastly set all the necessary fields... */
1327 
1328         sock_hold(sk);
1329         unix_peer(newsk)        = sk;
1330         newsk->sk_state         = TCP_ESTABLISHED;
1331         newsk->sk_type          = sk->sk_type;
1332         init_peercred(newsk);
1333         newu = unix_sk(newsk);
1334         RCU_INIT_POINTER(newsk->sk_wq, &newu->peer_wq);
1335         otheru = unix_sk(other);
1336 
1337         /* copy address information from listening to new sock*/
1338         if (otheru->addr) {
1339                 atomic_inc(&otheru->addr->refcnt);
1340                 newu->addr = otheru->addr;
1341         }
1342         if (otheru->path.dentry) {
1343                 path_get(&otheru->path);
1344                 newu->path = otheru->path;
1345         }
1346 
1347         /* Set credentials */
1348         copy_peercred(sk, other);
1349 
1350         sock->state     = SS_CONNECTED;
1351         sk->sk_state    = TCP_ESTABLISHED;
1352         sock_hold(newsk);
1353 
1354         smp_mb__after_atomic(); /* sock_hold() does an atomic_inc() */
1355         unix_peer(sk)   = newsk;
1356 
1357         unix_state_unlock(sk);
1358 
1359         /* take ten and and send info to listening sock */
1360         spin_lock(&other->sk_receive_queue.lock);
1361         __skb_queue_tail(&other->sk_receive_queue, skb);
1362         spin_unlock(&other->sk_receive_queue.lock);
1363         unix_state_unlock(other);
1364         other->sk_data_ready(other);
1365         sock_put(other);
1366         return 0;
1367 
1368 out_unlock:
1369         if (other)
1370                 unix_state_unlock(other);
1371 
1372 out:
1373         kfree_skb(skb);
1374         if (newsk)
1375                 unix_release_sock(newsk, 0);
1376         if (other)
1377                 sock_put(other);
1378         return err;
1379 }
1380 
1381 static int unix_socketpair(struct socket *socka, struct socket *sockb)
1382 {
1383         struct sock *ska = socka->sk, *skb = sockb->sk;
1384 
1385         /* Join our sockets back to back */
1386         sock_hold(ska);
1387         sock_hold(skb);
1388         unix_peer(ska) = skb;
1389         unix_peer(skb) = ska;
1390         init_peercred(ska);
1391         init_peercred(skb);
1392 
1393         if (ska->sk_type != SOCK_DGRAM) {
1394                 ska->sk_state = TCP_ESTABLISHED;
1395                 skb->sk_state = TCP_ESTABLISHED;
1396                 socka->state  = SS_CONNECTED;
1397                 sockb->state  = SS_CONNECTED;
1398         }
1399         return 0;
1400 }
1401 
1402 static void unix_sock_inherit_flags(const struct socket *old,
1403                                     struct socket *new)
1404 {
1405         if (test_bit(SOCK_PASSCRED, &old->flags))
1406                 set_bit(SOCK_PASSCRED, &new->flags);
1407         if (test_bit(SOCK_PASSSEC, &old->flags))
1408                 set_bit(SOCK_PASSSEC, &new->flags);
1409 }
1410 
1411 static int unix_accept(struct socket *sock, struct socket *newsock, int flags)
1412 {
1413         struct sock *sk = sock->sk;
1414         struct sock *tsk;
1415         struct sk_buff *skb;
1416         int err;
1417 
1418         err = -EOPNOTSUPP;
1419         if (sock->type != SOCK_STREAM && sock->type != SOCK_SEQPACKET)
1420                 goto out;
1421 
1422         err = -EINVAL;
1423         if (sk->sk_state != TCP_LISTEN)
1424                 goto out;
1425 
1426         /* If socket state is TCP_LISTEN it cannot change (for now...),
1427          * so that no locks are necessary.
1428          */
1429 
1430         skb = skb_recv_datagram(sk, 0, flags&O_NONBLOCK, &err);
1431         if (!skb) {
1432                 /* This means receive shutdown. */
1433                 if (err == 0)
1434                         err = -EINVAL;
1435                 goto out;
1436         }
1437 
1438         tsk = skb->sk;
1439         skb_free_datagram(sk, skb);
1440         wake_up_interruptible(&unix_sk(sk)->peer_wait);
1441 
1442         /* attach accepted sock to socket */
1443         unix_state_lock(tsk);
1444         newsock->state = SS_CONNECTED;
1445         unix_sock_inherit_flags(sock, newsock);
1446         sock_graft(tsk, newsock);
1447         unix_state_unlock(tsk);
1448         return 0;
1449 
1450 out:
1451         return err;
1452 }
1453 
1454 
1455 static int unix_getname(struct socket *sock, struct sockaddr *uaddr, int *uaddr_len, int peer)
1456 {
1457         struct sock *sk = sock->sk;
1458         struct unix_sock *u;
1459         DECLARE_SOCKADDR(struct sockaddr_un *, sunaddr, uaddr);
1460         int err = 0;
1461 
1462         if (peer) {
1463                 sk = unix_peer_get(sk);
1464 
1465                 err = -ENOTCONN;
1466                 if (!sk)
1467                         goto out;
1468                 err = 0;
1469         } else {
1470                 sock_hold(sk);
1471         }
1472 
1473         u = unix_sk(sk);
1474         unix_state_lock(sk);
1475         if (!u->addr) {
1476                 sunaddr->sun_family = AF_UNIX;
1477                 sunaddr->sun_path[0] = 0;
1478                 *uaddr_len = sizeof(short);
1479         } else {
1480                 struct unix_address *addr = u->addr;
1481 
1482                 *uaddr_len = addr->len;
1483                 memcpy(sunaddr, addr->name, *uaddr_len);
1484         }
1485         unix_state_unlock(sk);
1486         sock_put(sk);
1487 out:
1488         return err;
1489 }
1490 
1491 static void unix_detach_fds(struct scm_cookie *scm, struct sk_buff *skb)
1492 {
1493         int i;
1494 
1495         scm->fp = UNIXCB(skb).fp;
1496         UNIXCB(skb).fp = NULL;
1497 
1498         for (i = scm->fp->count-1; i >= 0; i--)
1499                 unix_notinflight(scm->fp->user, scm->fp->fp[i]);
1500 }
1501 
1502 static void unix_destruct_scm(struct sk_buff *skb)
1503 {
1504         struct scm_cookie scm;
1505         memset(&scm, 0, sizeof(scm));
1506         scm.pid  = UNIXCB(skb).pid;
1507         if (UNIXCB(skb).fp)
1508                 unix_detach_fds(&scm, skb);
1509 
1510         /* Alas, it calls VFS */
1511         /* So fscking what? fput() had been SMP-safe since the last Summer */
1512         scm_destroy(&scm);
1513         sock_wfree(skb);
1514 }
1515 
1516 /*
1517  * The "user->unix_inflight" variable is protected by the garbage
1518  * collection lock, and we just read it locklessly here. If you go
1519  * over the limit, there might be a tiny race in actually noticing
1520  * it across threads. Tough.
1521  */
1522 static inline bool too_many_unix_fds(struct task_struct *p)
1523 {
1524         struct user_struct *user = current_user();
1525 
1526         if (unlikely(user->unix_inflight > task_rlimit(p, RLIMIT_NOFILE)))
1527                 return !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN);
1528         return false;
1529 }
1530 
1531 #define MAX_RECURSION_LEVEL 4
1532 
1533 static int unix_attach_fds(struct scm_cookie *scm, struct sk_buff *skb)
1534 {
1535         int i;
1536         unsigned char max_level = 0;
1537         int unix_sock_count = 0;
1538 
1539         if (too_many_unix_fds(current))
1540                 return -ETOOMANYREFS;
1541 
1542         for (i = scm->fp->count - 1; i >= 0; i--) {
1543                 struct sock *sk = unix_get_socket(scm->fp->fp[i]);
1544 
1545                 if (sk) {
1546                         unix_sock_count++;
1547                         max_level = max(max_level,
1548                                         unix_sk(sk)->recursion_level);
1549                 }
1550         }
1551         if (unlikely(max_level > MAX_RECURSION_LEVEL))
1552                 return -ETOOMANYREFS;
1553 
1554         /*
1555          * Need to duplicate file references for the sake of garbage
1556          * collection.  Otherwise a socket in the fps might become a
1557          * candidate for GC while the skb is not yet queued.
1558          */
1559         UNIXCB(skb).fp = scm_fp_dup(scm->fp);
1560         if (!UNIXCB(skb).fp)
1561                 return -ENOMEM;
1562 
1563         for (i = scm->fp->count - 1; i >= 0; i--)
1564                 unix_inflight(scm->fp->user, scm->fp->fp[i]);
1565         return max_level;
1566 }
1567 
1568 static int unix_scm_to_skb(struct scm_cookie *scm, struct sk_buff *skb, bool send_fds)
1569 {
1570         int err = 0;
1571 
1572         UNIXCB(skb).pid  = get_pid(scm->pid);
1573         UNIXCB(skb).uid = scm->creds.uid;
1574         UNIXCB(skb).gid = scm->creds.gid;
1575         UNIXCB(skb).fp = NULL;
1576         unix_get_secdata(scm, skb);
1577         if (scm->fp && send_fds)
1578                 err = unix_attach_fds(scm, skb);
1579 
1580         skb->destructor = unix_destruct_scm;
1581         return err;
1582 }
1583 
1584 static bool unix_passcred_enabled(const struct socket *sock,
1585                                   const struct sock *other)
1586 {
1587         return test_bit(SOCK_PASSCRED, &sock->flags) ||
1588                !other->sk_socket ||
1589                test_bit(SOCK_PASSCRED, &other->sk_socket->flags);
1590 }
1591 
1592 /*
1593  * Some apps rely on write() giving SCM_CREDENTIALS
1594  * We include credentials if source or destination socket
1595  * asserted SOCK_PASSCRED.
1596  */
1597 static void maybe_add_creds(struct sk_buff *skb, const struct socket *sock,
1598                             const struct sock *other)
1599 {
1600         if (UNIXCB(skb).pid)
1601                 return;
1602         if (unix_passcred_enabled(sock, other)) {
1603                 UNIXCB(skb).pid  = get_pid(task_tgid(current));
1604                 current_uid_gid(&UNIXCB(skb).uid, &UNIXCB(skb).gid);
1605         }
1606 }
1607 
1608 static int maybe_init_creds(struct scm_cookie *scm,
1609                             struct socket *socket,
1610                             const struct sock *other)
1611 {
1612         int err;
1613         struct msghdr msg = { .msg_controllen = 0 };
1614 
1615         err = scm_send(socket, &msg, scm, false);
1616         if (err)
1617                 return err;
1618 
1619         if (unix_passcred_enabled(socket, other)) {
1620                 scm->pid = get_pid(task_tgid(current));
1621                 current_uid_gid(&scm->creds.uid, &scm->creds.gid);
1622         }
1623         return err;
1624 }
1625 
1626 static bool unix_skb_scm_eq(struct sk_buff *skb,
1627                             struct scm_cookie *scm)
1628 {
1629         const struct unix_skb_parms *u = &UNIXCB(skb);
1630 
1631         return u->pid == scm->pid &&
1632                uid_eq(u->uid, scm->creds.uid) &&
1633                gid_eq(u->gid, scm->creds.gid) &&
1634                unix_secdata_eq(scm, skb);
1635 }
1636 
1637 /*
1638  *      Send AF_UNIX data.
1639  */
1640 
1641 static int unix_dgram_sendmsg(struct socket *sock, struct msghdr *msg,
1642                               size_t len)
1643 {
1644         struct sock *sk = sock->sk;
1645         struct net *net = sock_net(sk);
1646         struct unix_sock *u = unix_sk(sk);
1647         DECLARE_SOCKADDR(struct sockaddr_un *, sunaddr, msg->msg_name);
1648         struct sock *other = NULL;
1649         int namelen = 0; /* fake GCC */
1650         int err;
1651         unsigned int hash;
1652         struct sk_buff *skb;
1653         long timeo;
1654         struct scm_cookie scm;
1655         int max_level;
1656         int data_len = 0;
1657         int sk_locked;
1658 
1659         wait_for_unix_gc();
1660         err = scm_send(sock, msg, &scm, false);
1661         if (err < 0)
1662                 return err;
1663 
1664         err = -EOPNOTSUPP;
1665         if (msg->msg_flags&MSG_OOB)
1666                 goto out;
1667 
1668         if (msg->msg_namelen) {
1669                 err = unix_mkname(sunaddr, msg->msg_namelen, &hash);
1670                 if (err < 0)
1671                         goto out;
1672                 namelen = err;
1673         } else {
1674                 sunaddr = NULL;
1675                 err = -ENOTCONN;
1676                 other = unix_peer_get(sk);
1677                 if (!other)
1678                         goto out;
1679         }
1680 
1681         if (test_bit(SOCK_PASSCRED, &sock->flags) && !u->addr
1682             && (err = unix_autobind(sock)) != 0)
1683                 goto out;
1684 
1685         err = -EMSGSIZE;
1686         if (len > sk->sk_sndbuf - 32)
1687                 goto out;
1688 
1689         if (len > SKB_MAX_ALLOC) {
1690                 data_len = min_t(size_t,
1691                                  len - SKB_MAX_ALLOC,
1692                                  MAX_SKB_FRAGS * PAGE_SIZE);
1693                 data_len = PAGE_ALIGN(data_len);
1694 
1695                 BUILD_BUG_ON(SKB_MAX_ALLOC < PAGE_SIZE);
1696         }
1697 
1698         skb = sock_alloc_send_pskb(sk, len - data_len, data_len,
1699                                    msg->msg_flags & MSG_DONTWAIT, &err,
1700                                    PAGE_ALLOC_COSTLY_ORDER);
1701         if (skb == NULL)
1702                 goto out;
1703 
1704         err = unix_scm_to_skb(&scm, skb, true);
1705         if (err < 0)
1706                 goto out_free;
1707         max_level = err + 1;
1708 
1709         skb_put(skb, len - data_len);
1710         skb->data_len = data_len;
1711         skb->len = len;
1712         err = skb_copy_datagram_from_iter(skb, 0, &msg->msg_iter, len);
1713         if (err)
1714                 goto out_free;
1715 
1716         timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT);
1717 
1718 restart:
1719         if (!other) {
1720                 err = -ECONNRESET;
1721                 if (sunaddr == NULL)
1722                         goto out_free;
1723 
1724                 other = unix_find_other(net, sunaddr, namelen, sk->sk_type,
1725                                         hash, &err);
1726                 if (other == NULL)
1727                         goto out_free;
1728         }
1729 
1730         if (sk_filter(other, skb) < 0) {
1731                 /* Toss the packet but do not return any error to the sender */
1732                 err = len;
1733                 goto out_free;
1734         }
1735 
1736         sk_locked = 0;
1737         unix_state_lock(other);
1738 restart_locked:
1739         err = -EPERM;
1740         if (!unix_may_send(sk, other))
1741                 goto out_unlock;
1742 
1743         if (unlikely(sock_flag(other, SOCK_DEAD))) {
1744                 /*
1745                  *      Check with 1003.1g - what should
1746                  *      datagram error
1747                  */
1748                 unix_state_unlock(other);
1749                 sock_put(other);
1750 
1751                 if (!sk_locked)
1752                         unix_state_lock(sk);
1753 
1754                 err = 0;
1755                 if (unix_peer(sk) == other) {
1756                         unix_peer(sk) = NULL;
1757                         unix_dgram_peer_wake_disconnect_wakeup(sk, other);
1758 
1759                         unix_state_unlock(sk);
1760 
1761                         unix_dgram_disconnected(sk, other);
1762                         sock_put(other);
1763                         err = -ECONNREFUSED;
1764                 } else {
1765                         unix_state_unlock(sk);
1766                 }
1767 
1768                 other = NULL;
1769                 if (err)
1770                         goto out_free;
1771                 goto restart;
1772         }
1773 
1774         err = -EPIPE;
1775         if (other->sk_shutdown & RCV_SHUTDOWN)
1776                 goto out_unlock;
1777 
1778         if (sk->sk_type != SOCK_SEQPACKET) {
1779                 err = security_unix_may_send(sk->sk_socket, other->sk_socket);
1780                 if (err)
1781                         goto out_unlock;
1782         }
1783 
1784         /* other == sk && unix_peer(other) != sk if
1785          * - unix_peer(sk) == NULL, destination address bound to sk
1786          * - unix_peer(sk) == sk by time of get but disconnected before lock
1787          */
1788         if (other != sk &&
1789             unlikely(unix_peer(other) != sk && unix_recvq_full(other))) {
1790                 if (timeo) {
1791                         timeo = unix_wait_for_peer(other, timeo);
1792 
1793                         err = sock_intr_errno(timeo);
1794                         if (signal_pending(current))
1795                                 goto out_free;
1796 
1797                         goto restart;
1798                 }
1799 
1800                 if (!sk_locked) {
1801                         unix_state_unlock(other);
1802                         unix_state_double_lock(sk, other);
1803                 }
1804 
1805                 if (unix_peer(sk) != other ||
1806                     unix_dgram_peer_wake_me(sk, other)) {
1807                         err = -EAGAIN;
1808                         sk_locked = 1;
1809                         goto out_unlock;
1810                 }
1811 
1812                 if (!sk_locked) {
1813                         sk_locked = 1;
1814                         goto restart_locked;
1815                 }
1816         }
1817 
1818         if (unlikely(sk_locked))
1819                 unix_state_unlock(sk);
1820 
1821         if (sock_flag(other, SOCK_RCVTSTAMP))
1822                 __net_timestamp(skb);
1823         maybe_add_creds(skb, sock, other);
1824         skb_queue_tail(&other->sk_receive_queue, skb);
1825         if (max_level > unix_sk(other)->recursion_level)
1826                 unix_sk(other)->recursion_level = max_level;
1827         unix_state_unlock(other);
1828         other->sk_data_ready(other);
1829         sock_put(other);
1830         scm_destroy(&scm);
1831         return len;
1832 
1833 out_unlock:
1834         if (sk_locked)
1835                 unix_state_unlock(sk);
1836         unix_state_unlock(other);
1837 out_free:
1838         kfree_skb(skb);
1839 out:
1840         if (other)
1841                 sock_put(other);
1842         scm_destroy(&scm);
1843         return err;
1844 }
1845 
1846 /* We use paged skbs for stream sockets, and limit occupancy to 32768
1847  * bytes, and a minimun of a full page.
1848  */
1849 #define UNIX_SKB_FRAGS_SZ (PAGE_SIZE << get_order(32768))
1850 
1851 static int unix_stream_sendmsg(struct socket *sock, struct msghdr *msg,
1852                                size_t len)
1853 {
1854         struct sock *sk = sock->sk;
1855         struct sock *other = NULL;
1856         int err, size;
1857         struct sk_buff *skb;
1858         int sent = 0;
1859         struct scm_cookie scm;
1860         bool fds_sent = false;
1861         int max_level;
1862         int data_len;
1863 
1864         wait_for_unix_gc();
1865         err = scm_send(sock, msg, &scm, false);
1866         if (err < 0)
1867                 return err;
1868 
1869         err = -EOPNOTSUPP;
1870         if (msg->msg_flags&MSG_OOB)
1871                 goto out_err;
1872 
1873         if (msg->msg_namelen) {
1874                 err = sk->sk_state == TCP_ESTABLISHED ? -EISCONN : -EOPNOTSUPP;
1875                 goto out_err;
1876         } else {
1877                 err = -ENOTCONN;
1878                 other = unix_peer(sk);
1879                 if (!other)
1880                         goto out_err;
1881         }
1882 
1883         if (sk->sk_shutdown & SEND_SHUTDOWN)
1884                 goto pipe_err;
1885 
1886         while (sent < len) {
1887                 size = len - sent;
1888 
1889                 /* Keep two messages in the pipe so it schedules better */
1890                 size = min_t(int, size, (sk->sk_sndbuf >> 1) - 64);
1891 
1892                 /* allow fallback to order-0 allocations */
1893                 size = min_t(int, size, SKB_MAX_HEAD(0) + UNIX_SKB_FRAGS_SZ);
1894 
1895                 data_len = max_t(int, 0, size - SKB_MAX_HEAD(0));
1896 
1897                 data_len = min_t(size_t, size, PAGE_ALIGN(data_len));
1898 
1899                 skb = sock_alloc_send_pskb(sk, size - data_len, data_len,
1900                                            msg->msg_flags & MSG_DONTWAIT, &err,
1901                                            get_order(UNIX_SKB_FRAGS_SZ));
1902                 if (!skb)
1903                         goto out_err;
1904 
1905                 /* Only send the fds in the first buffer */
1906                 err = unix_scm_to_skb(&scm, skb, !fds_sent);
1907                 if (err < 0) {
1908                         kfree_skb(skb);
1909                         goto out_err;
1910                 }
1911                 max_level = err + 1;
1912                 fds_sent = true;
1913 
1914                 skb_put(skb, size - data_len);
1915                 skb->data_len = data_len;
1916                 skb->len = size;
1917                 err = skb_copy_datagram_from_iter(skb, 0, &msg->msg_iter, size);
1918                 if (err) {
1919                         kfree_skb(skb);
1920                         goto out_err;
1921                 }
1922 
1923                 unix_state_lock(other);
1924 
1925                 if (sock_flag(other, SOCK_DEAD) ||
1926                     (other->sk_shutdown & RCV_SHUTDOWN))
1927                         goto pipe_err_free;
1928 
1929                 maybe_add_creds(skb, sock, other);
1930                 skb_queue_tail(&other->sk_receive_queue, skb);
1931                 if (max_level > unix_sk(other)->recursion_level)
1932                         unix_sk(other)->recursion_level = max_level;
1933                 unix_state_unlock(other);
1934                 other->sk_data_ready(other);
1935                 sent += size;
1936         }
1937 
1938         scm_destroy(&scm);
1939 
1940         return sent;
1941 
1942 pipe_err_free:
1943         unix_state_unlock(other);
1944         kfree_skb(skb);
1945 pipe_err:
1946         if (sent == 0 && !(msg->msg_flags&MSG_NOSIGNAL))
1947                 send_sig(SIGPIPE, current, 0);
1948         err = -EPIPE;
1949 out_err:
1950         scm_destroy(&scm);
1951         return sent ? : err;
1952 }
1953 
1954 static ssize_t unix_stream_sendpage(struct socket *socket, struct page *page,
1955                                     int offset, size_t size, int flags)
1956 {
1957         int err;
1958         bool send_sigpipe = false;
1959         bool init_scm = true;
1960         struct scm_cookie scm;
1961         struct sock *other, *sk = socket->sk;
1962         struct sk_buff *skb, *newskb = NULL, *tail = NULL;
1963 
1964         if (flags & MSG_OOB)
1965                 return -EOPNOTSUPP;
1966 
1967         other = unix_peer(sk);
1968         if (!other || sk->sk_state != TCP_ESTABLISHED)
1969                 return -ENOTCONN;
1970 
1971         if (false) {
1972 alloc_skb:
1973                 unix_state_unlock(other);
1974                 mutex_unlock(&unix_sk(other)->readlock);
1975                 newskb = sock_alloc_send_pskb(sk, 0, 0, flags & MSG_DONTWAIT,
1976                                               &err, 0);
1977                 if (!newskb)
1978                         goto err;
1979         }
1980 
1981         /* we must acquire readlock as we modify already present
1982          * skbs in the sk_receive_queue and mess with skb->len
1983          */
1984         err = mutex_lock_interruptible(&unix_sk(other)->readlock);
1985         if (err) {
1986                 err = flags & MSG_DONTWAIT ? -EAGAIN : -ERESTARTSYS;
1987                 goto err;
1988         }
1989 
1990         if (sk->sk_shutdown & SEND_SHUTDOWN) {
1991                 err = -EPIPE;
1992                 send_sigpipe = true;
1993                 goto err_unlock;
1994         }
1995 
1996         unix_state_lock(other);
1997 
1998         if (sock_flag(other, SOCK_DEAD) ||
1999             other->sk_shutdown & RCV_SHUTDOWN) {
2000                 err = -EPIPE;
2001                 send_sigpipe = true;
2002                 goto err_state_unlock;
2003         }
2004 
2005         if (init_scm) {
2006                 err = maybe_init_creds(&scm, socket, other);
2007                 if (err)
2008                         goto err_state_unlock;
2009                 init_scm = false;
2010         }
2011 
2012         skb = skb_peek_tail(&other->sk_receive_queue);
2013         if (tail && tail == skb) {
2014                 skb = newskb;
2015         } else if (!skb || !unix_skb_scm_eq(skb, &scm)) {
2016                 if (newskb) {
2017                         skb = newskb;
2018                 } else {
2019                         tail = skb;
2020                         goto alloc_skb;
2021                 }
2022         } else if (newskb) {
2023                 /* this is fast path, we don't necessarily need to
2024                  * call to kfree_skb even though with newskb == NULL
2025                  * this - does no harm
2026                  */
2027                 consume_skb(newskb);
2028                 newskb = NULL;
2029         }
2030 
2031         if (skb_append_pagefrags(skb, page, offset, size)) {
2032                 tail = skb;
2033                 goto alloc_skb;
2034         }
2035 
2036         skb->len += size;
2037         skb->data_len += size;
2038         skb->truesize += size;
2039         atomic_add(size, &sk->sk_wmem_alloc);
2040 
2041         if (newskb) {
2042                 err = unix_scm_to_skb(&scm, skb, false);
2043                 if (err)
2044                         goto err_state_unlock;
2045                 spin_lock(&other->sk_receive_queue.lock);
2046                 __skb_queue_tail(&other->sk_receive_queue, newskb);
2047                 spin_unlock(&other->sk_receive_queue.lock);
2048         }
2049 
2050         unix_state_unlock(other);
2051         mutex_unlock(&unix_sk(other)->readlock);
2052 
2053         other->sk_data_ready(other);
2054         scm_destroy(&scm);
2055         return size;
2056 
2057 err_state_unlock:
2058         unix_state_unlock(other);
2059 err_unlock:
2060         mutex_unlock(&unix_sk(other)->readlock);
2061 err:
2062         kfree_skb(newskb);
2063         if (send_sigpipe && !(flags & MSG_NOSIGNAL))
2064                 send_sig(SIGPIPE, current, 0);
2065         if (!init_scm)
2066                 scm_destroy(&scm);
2067         return err;
2068 }
2069 
2070 static int unix_seqpacket_sendmsg(struct socket *sock, struct msghdr *msg,
2071                                   size_t len)
2072 {
2073         int err;
2074         struct sock *sk = sock->sk;
2075 
2076         err = sock_error(sk);
2077         if (err)
2078                 return err;
2079 
2080         if (sk->sk_state != TCP_ESTABLISHED)
2081                 return -ENOTCONN;
2082 
2083         if (msg->msg_namelen)
2084                 msg->msg_namelen = 0;
2085 
2086         return unix_dgram_sendmsg(sock, msg, len);
2087 }
2088 
2089 static int unix_seqpacket_recvmsg(struct socket *sock, struct msghdr *msg,
2090                                   size_t size, int flags)
2091 {
2092         struct sock *sk = sock->sk;
2093 
2094         if (sk->sk_state != TCP_ESTABLISHED)
2095                 return -ENOTCONN;
2096 
2097         return unix_dgram_recvmsg(sock, msg, size, flags);
2098 }
2099 
2100 static void unix_copy_addr(struct msghdr *msg, struct sock *sk)
2101 {
2102         struct unix_sock *u = unix_sk(sk);
2103 
2104         if (u->addr) {
2105                 msg->msg_namelen = u->addr->len;
2106                 memcpy(msg->msg_name, u->addr->name, u->addr->len);
2107         }
2108 }
2109 
2110 static int unix_dgram_recvmsg(struct socket *sock, struct msghdr *msg,
2111                               size_t size, int flags)
2112 {
2113         struct scm_cookie scm;
2114         struct sock *sk = sock->sk;
2115         struct unix_sock *u = unix_sk(sk);
2116         struct sk_buff *skb, *last;
2117         long timeo;
2118         int err;
2119         int peeked, skip;
2120 
2121         err = -EOPNOTSUPP;
2122         if (flags&MSG_OOB)
2123                 goto out;
2124 
2125         timeo = sock_rcvtimeo(sk, flags & MSG_DONTWAIT);
2126 
2127         do {
2128                 mutex_lock(&u->readlock);
2129 
2130                 skip = sk_peek_offset(sk, flags);
2131                 skb = __skb_try_recv_datagram(sk, flags, &peeked, &skip, &err,
2132                                               &last);
2133                 if (skb)
2134                         break;
2135 
2136                 mutex_unlock(&u->readlock);
2137 
2138                 if (err != -EAGAIN)
2139                         break;
2140         } while (timeo &&
2141                  !__skb_wait_for_more_packets(sk, &err, &timeo, last));
2142 
2143         if (!skb) { /* implies readlock unlocked */
2144                 unix_state_lock(sk);
2145                 /* Signal EOF on disconnected non-blocking SEQPACKET socket. */
2146                 if (sk->sk_type == SOCK_SEQPACKET && err == -EAGAIN &&
2147                     (sk->sk_shutdown & RCV_SHUTDOWN))
2148                         err = 0;
2149                 unix_state_unlock(sk);
2150                 goto out;
2151         }
2152 
2153         if (wq_has_sleeper(&u->peer_wait))
2154                 wake_up_interruptible_sync_poll(&u->peer_wait,
2155                                                 POLLOUT | POLLWRNORM |
2156                                                 POLLWRBAND);
2157 
2158         if (ccs_socket_post_recvmsg_permission(sk, skb, flags)) {
2159                 err = -EAGAIN; /* Hope less harmful than -EPERM. */
2160                 goto out_unlock;
2161         }
2162         if (msg->msg_name)
2163                 unix_copy_addr(msg, skb->sk);
2164 
2165         if (size > skb->len - skip)
2166                 size = skb->len - skip;
2167         else if (size < skb->len - skip)
2168                 msg->msg_flags |= MSG_TRUNC;
2169 
2170         err = skb_copy_datagram_msg(skb, skip, msg, size);
2171         if (err)
2172                 goto out_free;
2173 
2174         if (sock_flag(sk, SOCK_RCVTSTAMP))
2175                 __sock_recv_timestamp(msg, sk, skb);
2176 
2177         memset(&scm, 0, sizeof(scm));
2178 
2179         scm_set_cred(&scm, UNIXCB(skb).pid, UNIXCB(skb).uid, UNIXCB(skb).gid);
2180         unix_set_secdata(&scm, skb);
2181 
2182         if (!(flags & MSG_PEEK)) {
2183                 if (UNIXCB(skb).fp)
2184                         unix_detach_fds(&scm, skb);
2185 
2186                 sk_peek_offset_bwd(sk, skb->len);
2187         } else {
2188                 /* It is questionable: on PEEK we could:
2189                    - do not return fds - good, but too simple 8)
2190                    - return fds, and do not return them on read (old strategy,
2191                      apparently wrong)
2192                    - clone fds (I chose it for now, it is the most universal
2193                      solution)
2194 
2195                    POSIX 1003.1g does not actually define this clearly
2196                    at all. POSIX 1003.1g doesn't define a lot of things
2197                    clearly however!
2198 
2199                 */
2200 
2201                 sk_peek_offset_fwd(sk, size);
2202 
2203                 if (UNIXCB(skb).fp)
2204                         scm.fp = scm_fp_dup(UNIXCB(skb).fp);
2205         }
2206         err = (flags & MSG_TRUNC) ? skb->len - skip : size;
2207 
2208         scm_recv(sock, msg, &scm, flags);
2209 
2210 out_free:
2211         skb_free_datagram(sk, skb);
2212 out_unlock:
2213         mutex_unlock(&u->readlock);
2214 out:
2215         return err;
2216 }
2217 
2218 /*
2219  *      Sleep until more data has arrived. But check for races..
2220  */
2221 static long unix_stream_data_wait(struct sock *sk, long timeo,
2222                                   struct sk_buff *last, unsigned int last_len)
2223 {
2224         struct sk_buff *tail;
2225         DEFINE_WAIT(wait);
2226 
2227         unix_state_lock(sk);
2228 
2229         for (;;) {
2230                 prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
2231 
2232                 tail = skb_peek_tail(&sk->sk_receive_queue);
2233                 if (tail != last ||
2234                     (tail && tail->len != last_len) ||
2235                     sk->sk_err ||
2236                     (sk->sk_shutdown & RCV_SHUTDOWN) ||
2237                     signal_pending(current) ||
2238                     !timeo)
2239                         break;
2240 
2241                 sk_set_bit(SOCKWQ_ASYNC_WAITDATA, sk);
2242                 unix_state_unlock(sk);
2243                 timeo = freezable_schedule_timeout(timeo);
2244                 unix_state_lock(sk);
2245 
2246                 if (sock_flag(sk, SOCK_DEAD))
2247                         break;
2248 
2249                 sk_clear_bit(SOCKWQ_ASYNC_WAITDATA, sk);
2250         }
2251 
2252         finish_wait(sk_sleep(sk), &wait);
2253         unix_state_unlock(sk);
2254         return timeo;
2255 }
2256 
2257 static unsigned int unix_skb_len(const struct sk_buff *skb)
2258 {
2259         return skb->len - UNIXCB(skb).consumed;
2260 }
2261 
2262 struct unix_stream_read_state {
2263         int (*recv_actor)(struct sk_buff *, int, int,
2264                           struct unix_stream_read_state *);
2265         struct socket *socket;
2266         struct msghdr *msg;
2267         struct pipe_inode_info *pipe;
2268         size_t size;
2269         int flags;
2270         unsigned int splice_flags;
2271 };
2272 
2273 static int unix_stream_read_generic(struct unix_stream_read_state *state)
2274 {
2275         struct scm_cookie scm;
2276         struct socket *sock = state->socket;
2277         struct sock *sk = sock->sk;
2278         struct unix_sock *u = unix_sk(sk);
2279         int copied = 0;
2280         int flags = state->flags;
2281         int noblock = flags & MSG_DONTWAIT;
2282         bool check_creds = false;
2283         int target;
2284         int err = 0;
2285         long timeo;
2286         int skip;
2287         size_t size = state->size;
2288         unsigned int last_len;
2289 
2290         if (unlikely(sk->sk_state != TCP_ESTABLISHED)) {
2291                 err = -EINVAL;
2292                 goto out;
2293         }
2294 
2295         if (unlikely(flags & MSG_OOB)) {
2296                 err = -EOPNOTSUPP;
2297                 goto out;
2298         }
2299 
2300         target = sock_rcvlowat(sk, flags & MSG_WAITALL, size);
2301         timeo = sock_rcvtimeo(sk, noblock);
2302 
2303         memset(&scm, 0, sizeof(scm));
2304 
2305         /* Lock the socket to prevent queue disordering
2306          * while sleeps in memcpy_tomsg
2307          */
2308         mutex_lock(&u->readlock);
2309 
2310         if (flags & MSG_PEEK)
2311                 skip = sk_peek_offset(sk, flags);
2312         else
2313                 skip = 0;
2314 
2315         do {
2316                 int chunk;
2317                 bool drop_skb;
2318                 struct sk_buff *skb, *last;
2319 
2320 redo:
2321                 unix_state_lock(sk);
2322                 if (sock_flag(sk, SOCK_DEAD)) {
2323                         err = -ECONNRESET;
2324                         goto unlock;
2325                 }
2326                 last = skb = skb_peek(&sk->sk_receive_queue);
2327                 last_len = last ? last->len : 0;
2328 again:
2329                 if (skb == NULL) {
2330                         unix_sk(sk)->recursion_level = 0;
2331                         if (copied >= target)
2332                                 goto unlock;
2333 
2334                         /*
2335                          *      POSIX 1003.1g mandates this order.
2336                          */
2337 
2338                         err = sock_error(sk);
2339                         if (err)
2340                                 goto unlock;
2341                         if (sk->sk_shutdown & RCV_SHUTDOWN)
2342                                 goto unlock;
2343 
2344                         unix_state_unlock(sk);
2345                         if (!timeo) {
2346                                 err = -EAGAIN;
2347                                 break;
2348                         }
2349 
2350                         mutex_unlock(&u->readlock);
2351 
2352                         timeo = unix_stream_data_wait(sk, timeo, last,
2353                                                       last_len);
2354 
2355                         if (signal_pending(current)) {
2356                                 err = sock_intr_errno(timeo);
2357                                 scm_destroy(&scm);
2358                                 goto out;
2359                         }
2360 
2361                         mutex_lock(&u->readlock);
2362                         goto redo;
2363 unlock:
2364                         unix_state_unlock(sk);
2365                         break;
2366                 }
2367 
2368                 while (skip >= unix_skb_len(skb)) {
2369                         skip -= unix_skb_len(skb);
2370                         last = skb;
2371                         last_len = skb->len;
2372                         skb = skb_peek_next(skb, &sk->sk_receive_queue);
2373                         if (!skb)
2374                                 goto again;
2375                 }
2376 
2377                 unix_state_unlock(sk);
2378 
2379                 if (check_creds) {
2380                         /* Never glue messages from different writers */
2381                         if (!unix_skb_scm_eq(skb, &scm))
2382                                 break;
2383                 } else if (test_bit(SOCK_PASSCRED, &sock->flags)) {
2384                         /* Copy credentials */
2385                         scm_set_cred(&scm, UNIXCB(skb).pid, UNIXCB(skb).uid, UNIXCB(skb).gid);
2386                         unix_set_secdata(&scm, skb);
2387                         check_creds = true;
2388                 }
2389 
2390                 /* Copy address just once */
2391                 if (state->msg && state->msg->msg_name) {
2392                         DECLARE_SOCKADDR(struct sockaddr_un *, sunaddr,
2393                                          state->msg->msg_name);
2394                         unix_copy_addr(state->msg, skb->sk);
2395                         sunaddr = NULL;
2396                 }
2397 
2398                 chunk = min_t(unsigned int, unix_skb_len(skb) - skip, size);
2399                 skb_get(skb);
2400                 chunk = state->recv_actor(skb, skip, chunk, state);
2401                 drop_skb = !unix_skb_len(skb);
2402                 /* skb is only safe to use if !drop_skb */
2403                 consume_skb(skb);
2404                 if (chunk < 0) {
2405                         if (copied == 0)
2406                                 copied = -EFAULT;
2407                         break;
2408                 }
2409                 copied += chunk;
2410                 size -= chunk;
2411 
2412                 if (drop_skb) {
2413                         /* the skb was touched by a concurrent reader;
2414                          * we should not expect anything from this skb
2415                          * anymore and assume it invalid - we can be
2416                          * sure it was dropped from the socket queue
2417                          *
2418                          * let's report a short read
2419                          */
2420                         err = 0;
2421                         break;
2422                 }
2423 
2424                 /* Mark read part of skb as used */
2425                 if (!(flags & MSG_PEEK)) {
2426                         UNIXCB(skb).consumed += chunk;
2427 
2428                         sk_peek_offset_bwd(sk, chunk);
2429 
2430                         if (UNIXCB(skb).fp)
2431                                 unix_detach_fds(&scm, skb);
2432 
2433                         if (unix_skb_len(skb))
2434                                 break;
2435 
2436                         skb_unlink(skb, &sk->sk_receive_queue);
2437                         consume_skb(skb);
2438 
2439                         if (scm.fp)
2440                                 break;
2441                 } else {
2442                         /* It is questionable, see note in unix_dgram_recvmsg.
2443                          */
2444                         if (UNIXCB(skb).fp)
2445                                 scm.fp = scm_fp_dup(UNIXCB(skb).fp);
2446 
2447                         sk_peek_offset_fwd(sk, chunk);
2448 
2449                         if (UNIXCB(skb).fp)
2450                                 break;
2451 
2452                         skip = 0;
2453                         last = skb;
2454                         last_len = skb->len;
2455                         unix_state_lock(sk);
2456                         skb = skb_peek_next(skb, &sk->sk_receive_queue);
2457                         if (skb)
2458                                 goto again;
2459                         unix_state_unlock(sk);
2460                         break;
2461                 }
2462         } while (size);
2463 
2464         mutex_unlock(&u->readlock);
2465         if (state->msg)
2466                 scm_recv(sock, state->msg, &scm, flags);
2467         else
2468                 scm_destroy(&scm);
2469 out:
2470         return copied ? : err;
2471 }
2472 
2473 static int unix_stream_read_actor(struct sk_buff *skb,
2474                                   int skip, int chunk,
2475                                   struct unix_stream_read_state *state)
2476 {
2477         int ret;
2478 
2479         ret = skb_copy_datagram_msg(skb, UNIXCB(skb).consumed + skip,
2480                                     state->msg, chunk);
2481         return ret ?: chunk;
2482 }
2483 
2484 static int unix_stream_recvmsg(struct socket *sock, struct msghdr *msg,
2485                                size_t size, int flags)
2486 {
2487         struct unix_stream_read_state state = {
2488                 .recv_actor = unix_stream_read_actor,
2489                 .socket = sock,
2490                 .msg = msg,
2491                 .size = size,
2492                 .flags = flags
2493         };
2494 
2495         return unix_stream_read_generic(&state);
2496 }
2497 
2498 static ssize_t skb_unix_socket_splice(struct sock *sk,
2499                                       struct pipe_inode_info *pipe,
2500                                       struct splice_pipe_desc *spd)
2501 {
2502         int ret;
2503         struct unix_sock *u = unix_sk(sk);
2504 
2505         mutex_unlock(&u->readlock);
2506         ret = splice_to_pipe(pipe, spd);
2507         mutex_lock(&u->readlock);
2508 
2509         return ret;
2510 }
2511 
2512 static int unix_stream_splice_actor(struct sk_buff *skb,
2513                                     int skip, int chunk,
2514                                     struct unix_stream_read_state *state)
2515 {
2516         return skb_splice_bits(skb, state->socket->sk,
2517                                UNIXCB(skb).consumed + skip,
2518                                state->pipe, chunk, state->splice_flags,
2519                                skb_unix_socket_splice);
2520 }
2521 
2522 static ssize_t unix_stream_splice_read(struct socket *sock,  loff_t *ppos,
2523                                        struct pipe_inode_info *pipe,
2524                                        size_t size, unsigned int flags)
2525 {
2526         struct unix_stream_read_state state = {
2527                 .recv_actor = unix_stream_splice_actor,
2528                 .socket = sock,
2529                 .pipe = pipe,
2530                 .size = size,
2531                 .splice_flags = flags,
2532         };
2533 
2534         if (unlikely(*ppos))
2535                 return -ESPIPE;
2536 
2537         if (sock->file->f_flags & O_NONBLOCK ||
2538             flags & SPLICE_F_NONBLOCK)
2539                 state.flags = MSG_DONTWAIT;
2540 
2541         return unix_stream_read_generic(&state);
2542 }
2543 
2544 static int unix_shutdown(struct socket *sock, int mode)
2545 {
2546         struct sock *sk = sock->sk;
2547         struct sock *other;
2548 
2549         if (mode < SHUT_RD || mode > SHUT_RDWR)
2550                 return -EINVAL;
2551         /* This maps:
2552          * SHUT_RD   (0) -> RCV_SHUTDOWN  (1)
2553          * SHUT_WR   (1) -> SEND_SHUTDOWN (2)
2554          * SHUT_RDWR (2) -> SHUTDOWN_MASK (3)
2555          */
2556         ++mode;
2557 
2558         unix_state_lock(sk);
2559         sk->sk_shutdown |= mode;
2560         other = unix_peer(sk);
2561         if (other)
2562                 sock_hold(other);
2563         unix_state_unlock(sk);
2564         sk->sk_state_change(sk);
2565 
2566         if (other &&
2567                 (sk->sk_type == SOCK_STREAM || sk->sk_type == SOCK_SEQPACKET)) {
2568 
2569                 int peer_mode = 0;
2570 
2571                 if (mode&RCV_SHUTDOWN)
2572                         peer_mode |= SEND_SHUTDOWN;
2573                 if (mode&SEND_SHUTDOWN)
2574                         peer_mode |= RCV_SHUTDOWN;
2575                 unix_state_lock(other);
2576                 other->sk_shutdown |= peer_mode;
2577                 unix_state_unlock(other);
2578                 other->sk_state_change(other);
2579                 if (peer_mode == SHUTDOWN_MASK)
2580                         sk_wake_async(other, SOCK_WAKE_WAITD, POLL_HUP);
2581                 else if (peer_mode & RCV_SHUTDOWN)
2582                         sk_wake_async(other, SOCK_WAKE_WAITD, POLL_IN);
2583         }
2584         if (other)
2585                 sock_put(other);
2586 
2587         return 0;
2588 }
2589 
2590 long unix_inq_len(struct sock *sk)
2591 {
2592         struct sk_buff *skb;
2593         long amount = 0;
2594 
2595         if (sk->sk_state == TCP_LISTEN)
2596                 return -EINVAL;
2597 
2598         spin_lock(&sk->sk_receive_queue.lock);
2599         if (sk->sk_type == SOCK_STREAM ||
2600             sk->sk_type == SOCK_SEQPACKET) {
2601                 skb_queue_walk(&sk->sk_receive_queue, skb)
2602                         amount += unix_skb_len(skb);
2603         } else {
2604                 skb = skb_peek(&sk->sk_receive_queue);
2605                 if (skb)
2606                         amount = skb->len;
2607         }
2608         spin_unlock(&sk->sk_receive_queue.lock);
2609 
2610         return amount;
2611 }
2612 EXPORT_SYMBOL_GPL(unix_inq_len);
2613 
2614 long unix_outq_len(struct sock *sk)
2615 {
2616         return sk_wmem_alloc_get(sk);
2617 }
2618 EXPORT_SYMBOL_GPL(unix_outq_len);
2619 
2620 static int unix_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
2621 {
2622         struct sock *sk = sock->sk;
2623         long amount = 0;
2624         int err;
2625 
2626         switch (cmd) {
2627         case SIOCOUTQ:
2628                 amount = unix_outq_len(sk);
2629                 err = put_user(amount, (int __user *)arg);
2630                 break;
2631         case SIOCINQ:
2632                 amount = unix_inq_len(sk);
2633                 if (amount < 0)
2634                         err = amount;
2635                 else
2636                         err = put_user(amount, (int __user *)arg);
2637                 break;
2638         default:
2639                 err = -ENOIOCTLCMD;
2640                 break;
2641         }
2642         return err;
2643 }
2644 
2645 static unsigned int unix_poll(struct file *file, struct socket *sock, poll_table *wait)
2646 {
2647         struct sock *sk = sock->sk;
2648         unsigned int mask;
2649 
2650         sock_poll_wait(file, sk_sleep(sk), wait);
2651         mask = 0;
2652 
2653         /* exceptional events? */
2654         if (sk->sk_err)
2655                 mask |= POLLERR;
2656         if (sk->sk_shutdown == SHUTDOWN_MASK)
2657                 mask |= POLLHUP;
2658         if (sk->sk_shutdown & RCV_SHUTDOWN)
2659                 mask |= POLLRDHUP | POLLIN | POLLRDNORM;
2660 
2661         /* readable? */
2662         if (!skb_queue_empty(&sk->sk_receive_queue))
2663                 mask |= POLLIN | POLLRDNORM;
2664 
2665         /* Connection-based need to check for termination and startup */
2666         if ((sk->sk_type == SOCK_STREAM || sk->sk_type == SOCK_SEQPACKET) &&
2667             sk->sk_state == TCP_CLOSE)
2668                 mask |= POLLHUP;
2669 
2670         /*
2671          * we set writable also when the other side has shut down the
2672          * connection. This prevents stuck sockets.
2673          */
2674         if (unix_writable(sk))
2675                 mask |= POLLOUT | POLLWRNORM | POLLWRBAND;
2676 
2677         return mask;
2678 }
2679 
2680 static unsigned int unix_dgram_poll(struct file *file, struct socket *sock,
2681                                     poll_table *wait)
2682 {
2683         struct sock *sk = sock->sk, *other;
2684         unsigned int mask, writable;
2685 
2686         sock_poll_wait(file, sk_sleep(sk), wait);
2687         mask = 0;
2688 
2689         /* exceptional events? */
2690         if (sk->sk_err || !skb_queue_empty(&sk->sk_error_queue))
2691                 mask |= POLLERR |
2692                         (sock_flag(sk, SOCK_SELECT_ERR_QUEUE) ? POLLPRI : 0);
2693 
2694         if (sk->sk_shutdown & RCV_SHUTDOWN)
2695                 mask |= POLLRDHUP | POLLIN | POLLRDNORM;
2696         if (sk->sk_shutdown == SHUTDOWN_MASK)
2697                 mask |= POLLHUP;
2698 
2699         /* readable? */
2700         if (!skb_queue_empty(&sk->sk_receive_queue))
2701                 mask |= POLLIN | POLLRDNORM;
2702 
2703         /* Connection-based need to check for termination and startup */
2704         if (sk->sk_type == SOCK_SEQPACKET) {
2705                 if (sk->sk_state == TCP_CLOSE)
2706                         mask |= POLLHUP;
2707                 /* connection hasn't started yet? */
2708                 if (sk->sk_state == TCP_SYN_SENT)
2709                         return mask;
2710         }
2711 
2712         /* No write status requested, avoid expensive OUT tests. */
2713         if (!(poll_requested_events(wait) & (POLLWRBAND|POLLWRNORM|POLLOUT)))
2714                 return mask;
2715 
2716         writable = unix_writable(sk);
2717         if (writable) {
2718                 unix_state_lock(sk);
2719 
2720                 other = unix_peer(sk);
2721                 if (other && unix_peer(other) != sk &&
2722                     unix_recvq_full(other) &&
2723                     unix_dgram_peer_wake_me(sk, other))
2724                         writable = 0;
2725 
2726                 unix_state_unlock(sk);
2727         }
2728 
2729         if (writable)
2730                 mask |= POLLOUT | POLLWRNORM | POLLWRBAND;
2731         else
2732                 sk_set_bit(SOCKWQ_ASYNC_NOSPACE, sk);
2733 
2734         return mask;
2735 }
2736 
2737 #ifdef CONFIG_PROC_FS
2738 
2739 #define BUCKET_SPACE (BITS_PER_LONG - (UNIX_HASH_BITS + 1) - 1)
2740 
2741 #define get_bucket(x) ((x) >> BUCKET_SPACE)
2742 #define get_offset(x) ((x) & ((1L << BUCKET_SPACE) - 1))
2743 #define set_bucket_offset(b, o) ((b) << BUCKET_SPACE | (o))
2744 
2745 static struct sock *unix_from_bucket(struct seq_file *seq, loff_t *pos)
2746 {
2747         unsigned long offset = get_offset(*pos);
2748         unsigned long bucket = get_bucket(*pos);
2749         struct sock *sk;
2750         unsigned long count = 0;
2751 
2752         for (sk = sk_head(&unix_socket_table[bucket]); sk; sk = sk_next(sk)) {
2753                 if (sock_net(sk) != seq_file_net(seq))
2754                         continue;
2755                 if (++count == offset)
2756                         break;
2757         }
2758 
2759         return sk;
2760 }
2761 
2762 static struct sock *unix_next_socket(struct seq_file *seq,
2763                                      struct sock *sk,
2764                                      loff_t *pos)
2765 {
2766         unsigned long bucket;
2767 
2768         while (sk > (struct sock *)SEQ_START_TOKEN) {
2769                 sk = sk_next(sk);
2770                 if (!sk)
2771                         goto next_bucket;
2772                 if (sock_net(sk) == seq_file_net(seq))
2773                         return sk;
2774         }
2775 
2776         do {
2777                 sk = unix_from_bucket(seq, pos);
2778                 if (sk)
2779                         return sk;
2780 
2781 next_bucket:
2782                 bucket = get_bucket(*pos) + 1;
2783                 *pos = set_bucket_offset(bucket, 1);
2784         } while (bucket < ARRAY_SIZE(unix_socket_table));
2785 
2786         return NULL;
2787 }
2788 
2789 static void *unix_seq_start(struct seq_file *seq, loff_t *pos)
2790         __acquires(unix_table_lock)
2791 {
2792         spin_lock(&unix_table_lock);
2793 
2794         if (!*pos)
2795                 return SEQ_START_TOKEN;
2796 
2797         if (get_bucket(*pos) >= ARRAY_SIZE(unix_socket_table))
2798                 return NULL;
2799 
2800         return unix_next_socket(seq, NULL, pos);
2801 }
2802 
2803 static void *unix_seq_next(struct seq_file *seq, void *v, loff_t *pos)
2804 {
2805         ++*pos;
2806         return unix_next_socket(seq, v, pos);
2807 }
2808 
2809 static void unix_seq_stop(struct seq_file *seq, void *v)
2810         __releases(unix_table_lock)
2811 {
2812         spin_unlock(&unix_table_lock);
2813 }
2814 
2815 static int unix_seq_show(struct seq_file *seq, void *v)
2816 {
2817 
2818         if (v == SEQ_START_TOKEN)
2819                 seq_puts(seq, "Num       RefCount Protocol Flags    Type St "
2820                          "Inode Path\n");
2821         else {
2822                 struct sock *s = v;
2823                 struct unix_sock *u = unix_sk(s);
2824                 unix_state_lock(s);
2825 
2826                 seq_printf(seq, "%pK: %08X %08X %08X %04X %02X %5lu",
2827                         s,
2828                         atomic_read(&s->sk_refcnt),
2829                         0,
2830                         s->sk_state == TCP_LISTEN ? __SO_ACCEPTCON : 0,
2831                         s->sk_type,
2832                         s->sk_socket ?
2833                         (s->sk_state == TCP_ESTABLISHED ? SS_CONNECTED : SS_UNCONNECTED) :
2834                         (s->sk_state == TCP_ESTABLISHED ? SS_CONNECTING : SS_DISCONNECTING),
2835                         sock_i_ino(s));
2836 
2837                 if (u->addr) {
2838                         int i, len;
2839                         seq_putc(seq, ' ');
2840 
2841                         i = 0;
2842                         len = u->addr->len - sizeof(short);
2843                         if (!UNIX_ABSTRACT(s))
2844                                 len--;
2845                         else {
2846                                 seq_putc(seq, '@');
2847                                 i++;
2848                         }
2849                         for ( ; i < len; i++)
2850                                 seq_putc(seq, u->addr->name->sun_path[i]);
2851                 }
2852                 unix_state_unlock(s);
2853                 seq_putc(seq, '\n');
2854         }
2855 
2856         return 0;
2857 }
2858 
2859 static const struct seq_operations unix_seq_ops = {
2860         .start  = unix_seq_start,
2861         .next   = unix_seq_next,
2862         .stop   = unix_seq_stop,
2863         .show   = unix_seq_show,
2864 };
2865 
2866 static int unix_seq_open(struct inode *inode, struct file *file)
2867 {
2868         return seq_open_net(inode, file, &unix_seq_ops,
2869                             sizeof(struct seq_net_private));
2870 }
2871 
2872 static const struct file_operations unix_seq_fops = {
2873         .owner          = THIS_MODULE,
2874         .open           = unix_seq_open,
2875         .read           = seq_read,
2876         .llseek         = seq_lseek,
2877         .release        = seq_release_net,
2878 };
2879 
2880 #endif
2881 
2882 static const struct net_proto_family unix_family_ops = {
2883         .family = PF_UNIX,
2884         .create = unix_create,
2885         .owner  = THIS_MODULE,
2886 };
2887 
2888 
2889 static int __net_init unix_net_init(struct net *net)
2890 {
2891         int error = -ENOMEM;
2892 
2893         net->unx.sysctl_max_dgram_qlen = 10;
2894         if (unix_sysctl_register(net))
2895                 goto out;
2896 
2897 #ifdef CONFIG_PROC_FS
2898         if (!proc_create("unix", 0, net->proc_net, &unix_seq_fops)) {
2899                 unix_sysctl_unregister(net);
2900                 goto out;
2901         }
2902 #endif
2903         error = 0;
2904 out:
2905         return error;
2906 }
2907 
2908 static void __net_exit unix_net_exit(struct net *net)
2909 {
2910         unix_sysctl_unregister(net);
2911         remove_proc_entry("unix", net->proc_net);
2912 }
2913 
2914 static struct pernet_operations unix_net_ops = {
2915         .init = unix_net_init,
2916         .exit = unix_net_exit,
2917 };
2918 
2919 static int __init af_unix_init(void)
2920 {
2921         int rc = -1;
2922 
2923         BUILD_BUG_ON(sizeof(struct unix_skb_parms) > FIELD_SIZEOF(struct sk_buff, cb));
2924 
2925         rc = proto_register(&unix_proto, 1);
2926         if (rc != 0) {
2927                 pr_crit("%s: Cannot create unix_sock SLAB cache!\n", __func__);
2928                 goto out;
2929         }
2930 
2931         sock_register(&unix_family_ops);
2932         register_pernet_subsys(&unix_net_ops);
2933 out:
2934         return rc;
2935 }
2936 
2937 static void __exit af_unix_exit(void)
2938 {
2939         sock_unregister(PF_UNIX);
2940         proto_unregister(&unix_proto);
2941         unregister_pernet_subsys(&unix_net_ops);
2942 }
2943 
2944 /* Earlier than device_initcall() so that other drivers invoking
2945    request_module() don't end up in a loop when modprobe tries
2946    to use a UNIX socket. But later than subsys_initcall() because
2947    we depend on stuff initialised there */
2948 fs_initcall(af_unix_init);
2949 module_exit(af_unix_exit);
2950 
2951 MODULE_LICENSE("GPL");
2952 MODULE_ALIAS_NETPROTO(PF_UNIX);
2953 

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