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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         memcpy(UNIXSID(skb), &scm->secid, sizeof(u32));
144 }
145 
146 static inline void unix_set_secdata(struct scm_cookie *scm, struct sk_buff *skb)
147 {
148         scm->secid = *UNIXSID(skb);
149 }
150 #else
151 static inline void unix_get_secdata(struct scm_cookie *scm, struct sk_buff *skb)
152 { }
153 
154 static inline void unix_set_secdata(struct scm_cookie *scm, struct sk_buff *skb)
155 { }
156 #endif /* CONFIG_SECURITY_NETWORK */
157 
158 /*
159  *  SMP locking strategy:
160  *    hash table is protected with spinlock unix_table_lock
161  *    each socket state is protected by separate spin lock.
162  */
163 
164 static inline unsigned int unix_hash_fold(__wsum n)
165 {
166         unsigned int hash = (__force unsigned int)csum_fold(n);
167 
168         hash ^= hash>>8;
169         return hash&(UNIX_HASH_SIZE-1);
170 }
171 
172 #define unix_peer(sk) (unix_sk(sk)->peer)
173 
174 static inline int unix_our_peer(struct sock *sk, struct sock *osk)
175 {
176         return unix_peer(osk) == sk;
177 }
178 
179 static inline int unix_may_send(struct sock *sk, struct sock *osk)
180 {
181         return unix_peer(osk) == NULL || unix_our_peer(sk, osk);
182 }
183 
184 static inline int unix_recvq_full(struct sock const *sk)
185 {
186         return skb_queue_len(&sk->sk_receive_queue) > sk->sk_max_ack_backlog;
187 }
188 
189 struct sock *unix_peer_get(struct sock *s)
190 {
191         struct sock *peer;
192 
193         unix_state_lock(s);
194         peer = unix_peer(s);
195         if (peer)
196                 sock_hold(peer);
197         unix_state_unlock(s);
198         return peer;
199 }
200 EXPORT_SYMBOL_GPL(unix_peer_get);
201 
202 static inline void unix_release_addr(struct unix_address *addr)
203 {
204         if (atomic_dec_and_test(&addr->refcnt))
205                 kfree(addr);
206 }
207 
208 /*
209  *      Check unix socket name:
210  *              - should be not zero length.
211  *              - if started by not zero, should be NULL terminated (FS object)
212  *              - if started by zero, it is abstract name.
213  */
214 
215 static int unix_mkname(struct sockaddr_un *sunaddr, int len, unsigned int *hashp)
216 {
217         if (len <= sizeof(short) || len > sizeof(*sunaddr))
218                 return -EINVAL;
219         if (!sunaddr || sunaddr->sun_family != AF_UNIX)
220                 return -EINVAL;
221         if (sunaddr->sun_path[0]) {
222                 /*
223                  * This may look like an off by one error but it is a bit more
224                  * subtle. 108 is the longest valid AF_UNIX path for a binding.
225                  * sun_path[108] doesn't as such exist.  However in kernel space
226                  * we are guaranteed that it is a valid memory location in our
227                  * kernel address buffer.
228                  */
229                 ((char *)sunaddr)[len] = 0;
230                 len = strlen(sunaddr->sun_path)+1+sizeof(short);
231                 return len;
232         }
233 
234         *hashp = unix_hash_fold(csum_partial(sunaddr, len, 0));
235         return len;
236 }
237 
238 static void __unix_remove_socket(struct sock *sk)
239 {
240         sk_del_node_init(sk);
241 }
242 
243 static void __unix_insert_socket(struct hlist_head *list, struct sock *sk)
244 {
245         WARN_ON(!sk_unhashed(sk));
246         sk_add_node(sk, list);
247 }
248 
249 static inline void unix_remove_socket(struct sock *sk)
250 {
251         spin_lock(&unix_table_lock);
252         __unix_remove_socket(sk);
253         spin_unlock(&unix_table_lock);
254 }
255 
256 static inline void unix_insert_socket(struct hlist_head *list, struct sock *sk)
257 {
258         spin_lock(&unix_table_lock);
259         __unix_insert_socket(list, sk);
260         spin_unlock(&unix_table_lock);
261 }
262 
263 static struct sock *__unix_find_socket_byname(struct net *net,
264                                               struct sockaddr_un *sunname,
265                                               int len, int type, unsigned int hash)
266 {
267         struct sock *s;
268 
269         sk_for_each(s, &unix_socket_table[hash ^ type]) {
270                 struct unix_sock *u = unix_sk(s);
271 
272                 if (!net_eq(sock_net(s), net))
273                         continue;
274 
275                 if (u->addr->len == len &&
276                     !memcmp(u->addr->name, sunname, len))
277                         goto found;
278         }
279         s = NULL;
280 found:
281         return s;
282 }
283 
284 static inline struct sock *unix_find_socket_byname(struct net *net,
285                                                    struct sockaddr_un *sunname,
286                                                    int len, int type,
287                                                    unsigned int hash)
288 {
289         struct sock *s;
290 
291         spin_lock(&unix_table_lock);
292         s = __unix_find_socket_byname(net, sunname, len, type, hash);
293         if (s)
294                 sock_hold(s);
295         spin_unlock(&unix_table_lock);
296         return s;
297 }
298 
299 static struct sock *unix_find_socket_byinode(struct inode *i)
300 {
301         struct sock *s;
302 
303         spin_lock(&unix_table_lock);
304         sk_for_each(s,
305                     &unix_socket_table[i->i_ino & (UNIX_HASH_SIZE - 1)]) {
306                 struct dentry *dentry = unix_sk(s)->path.dentry;
307 
308                 if (dentry && dentry->d_inode == i) {
309                         sock_hold(s);
310                         goto found;
311                 }
312         }
313         s = NULL;
314 found:
315         spin_unlock(&unix_table_lock);
316         return s;
317 }
318 
319 static inline int unix_writable(struct sock *sk)
320 {
321         return (atomic_read(&sk->sk_wmem_alloc) << 2) <= sk->sk_sndbuf;
322 }
323 
324 static void unix_write_space(struct sock *sk)
325 {
326         struct socket_wq *wq;
327 
328         rcu_read_lock();
329         if (unix_writable(sk)) {
330                 wq = rcu_dereference(sk->sk_wq);
331                 if (wq_has_sleeper(wq))
332                         wake_up_interruptible_sync_poll(&wq->wait,
333                                 POLLOUT | POLLWRNORM | POLLWRBAND);
334                 sk_wake_async(sk, SOCK_WAKE_SPACE, POLL_OUT);
335         }
336         rcu_read_unlock();
337 }
338 
339 /* When dgram socket disconnects (or changes its peer), we clear its receive
340  * queue of packets arrived from previous peer. First, it allows to do
341  * flow control based only on wmem_alloc; second, sk connected to peer
342  * may receive messages only from that peer. */
343 static void unix_dgram_disconnected(struct sock *sk, struct sock *other)
344 {
345         if (!skb_queue_empty(&sk->sk_receive_queue)) {
346                 skb_queue_purge(&sk->sk_receive_queue);
347                 wake_up_interruptible_all(&unix_sk(sk)->peer_wait);
348 
349                 /* If one link of bidirectional dgram pipe is disconnected,
350                  * we signal error. Messages are lost. Do not make this,
351                  * when peer was not connected to us.
352                  */
353                 if (!sock_flag(other, SOCK_DEAD) && unix_peer(other) == sk) {
354                         other->sk_err = ECONNRESET;
355                         other->sk_error_report(other);
356                 }
357         }
358 }
359 
360 static void unix_sock_destructor(struct sock *sk)
361 {
362         struct unix_sock *u = unix_sk(sk);
363 
364         skb_queue_purge(&sk->sk_receive_queue);
365 
366         WARN_ON(atomic_read(&sk->sk_wmem_alloc));
367         WARN_ON(!sk_unhashed(sk));
368         WARN_ON(sk->sk_socket);
369         if (!sock_flag(sk, SOCK_DEAD)) {
370                 pr_info("Attempt to release alive unix socket: %p\n", sk);
371                 return;
372         }
373 
374         if (u->addr)
375                 unix_release_addr(u->addr);
376 
377         atomic_long_dec(&unix_nr_socks);
378         local_bh_disable();
379         sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
380         local_bh_enable();
381 #ifdef UNIX_REFCNT_DEBUG
382         pr_debug("UNIX %p is destroyed, %ld are still alive.\n", sk,
383                 atomic_long_read(&unix_nr_socks));
384 #endif
385 }
386 
387 static void unix_release_sock(struct sock *sk, int embrion)
388 {
389         struct unix_sock *u = unix_sk(sk);
390         struct path path;
391         struct sock *skpair;
392         struct sk_buff *skb;
393         int state;
394 
395         unix_remove_socket(sk);
396 
397         /* Clear state */
398         unix_state_lock(sk);
399         sock_orphan(sk);
400         sk->sk_shutdown = SHUTDOWN_MASK;
401         path         = u->path;
402         u->path.dentry = NULL;
403         u->path.mnt = NULL;
404         state = sk->sk_state;
405         sk->sk_state = TCP_CLOSE;
406         unix_state_unlock(sk);
407 
408         wake_up_interruptible_all(&u->peer_wait);
409 
410         skpair = unix_peer(sk);
411 
412         if (skpair != NULL) {
413                 if (sk->sk_type == SOCK_STREAM || sk->sk_type == SOCK_SEQPACKET) {
414                         unix_state_lock(skpair);
415                         /* No more writes */
416                         skpair->sk_shutdown = SHUTDOWN_MASK;
417                         if (!skb_queue_empty(&sk->sk_receive_queue) || embrion)
418                                 skpair->sk_err = ECONNRESET;
419                         unix_state_unlock(skpair);
420                         skpair->sk_state_change(skpair);
421                         sk_wake_async(skpair, SOCK_WAKE_WAITD, POLL_HUP);
422                 }
423                 sock_put(skpair); /* It may now die */
424                 unix_peer(sk) = NULL;
425         }
426 
427         /* Try to flush out this socket. Throw out buffers at least */
428 
429         while ((skb = skb_dequeue(&sk->sk_receive_queue)) != NULL) {
430                 if (state == TCP_LISTEN)
431                         unix_release_sock(skb->sk, 1);
432                 /* passed fds are erased in the kfree_skb hook        */
433                 kfree_skb(skb);
434         }
435 
436         if (path.dentry)
437                 path_put(&path);
438 
439         sock_put(sk);
440 
441         /* ---- Socket is dead now and most probably destroyed ---- */
442 
443         /*
444          * Fixme: BSD difference: In BSD all sockets connected to us get
445          *        ECONNRESET and we die on the spot. In Linux we behave
446          *        like files and pipes do and wait for the last
447          *        dereference.
448          *
449          * Can't we simply set sock->err?
450          *
451          *        What the above comment does talk about? --ANK(980817)
452          */
453 
454         if (unix_tot_inflight)
455                 unix_gc();              /* Garbage collect fds */
456 }
457 
458 static void init_peercred(struct sock *sk)
459 {
460         put_pid(sk->sk_peer_pid);
461         if (sk->sk_peer_cred)
462                 put_cred(sk->sk_peer_cred);
463         sk->sk_peer_pid  = get_pid(task_tgid(current));
464         sk->sk_peer_cred = get_current_cred();
465 }
466 
467 static void copy_peercred(struct sock *sk, struct sock *peersk)
468 {
469         put_pid(sk->sk_peer_pid);
470         if (sk->sk_peer_cred)
471                 put_cred(sk->sk_peer_cred);
472         sk->sk_peer_pid  = get_pid(peersk->sk_peer_pid);
473         sk->sk_peer_cred = get_cred(peersk->sk_peer_cred);
474 }
475 
476 static int unix_listen(struct socket *sock, int backlog)
477 {
478         int err;
479         struct sock *sk = sock->sk;
480         struct unix_sock *u = unix_sk(sk);
481         struct pid *old_pid = NULL;
482 
483         err = -EOPNOTSUPP;
484         if (sock->type != SOCK_STREAM && sock->type != SOCK_SEQPACKET)
485                 goto out;       /* Only stream/seqpacket sockets accept */
486         err = -EINVAL;
487         if (!u->addr)
488                 goto out;       /* No listens on an unbound socket */
489         unix_state_lock(sk);
490         if (sk->sk_state != TCP_CLOSE && sk->sk_state != TCP_LISTEN)
491                 goto out_unlock;
492         if (backlog > sk->sk_max_ack_backlog)
493                 wake_up_interruptible_all(&u->peer_wait);
494         sk->sk_max_ack_backlog  = backlog;
495         sk->sk_state            = TCP_LISTEN;
496         /* set credentials so connect can copy them */
497         init_peercred(sk);
498         err = 0;
499 
500 out_unlock:
501         unix_state_unlock(sk);
502         put_pid(old_pid);
503 out:
504         return err;
505 }
506 
507 static int unix_release(struct socket *);
508 static int unix_bind(struct socket *, struct sockaddr *, int);
509 static int unix_stream_connect(struct socket *, struct sockaddr *,
510                                int addr_len, int flags);
511 static int unix_socketpair(struct socket *, struct socket *);
512 static int unix_accept(struct socket *, struct socket *, int);
513 static int unix_getname(struct socket *, struct sockaddr *, int *, int);
514 static unsigned int unix_poll(struct file *, struct socket *, poll_table *);
515 static unsigned int unix_dgram_poll(struct file *, struct socket *,
516                                     poll_table *);
517 static int unix_ioctl(struct socket *, unsigned int, unsigned long);
518 static int unix_shutdown(struct socket *, int);
519 static int unix_stream_sendmsg(struct kiocb *, struct socket *,
520                                struct msghdr *, size_t);
521 static int unix_stream_recvmsg(struct kiocb *, struct socket *,
522                                struct msghdr *, size_t, int);
523 static int unix_dgram_sendmsg(struct kiocb *, struct socket *,
524                               struct msghdr *, size_t);
525 static int unix_dgram_recvmsg(struct kiocb *, struct socket *,
526                               struct msghdr *, size_t, int);
527 static int unix_dgram_connect(struct socket *, struct sockaddr *,
528                               int, int);
529 static int unix_seqpacket_sendmsg(struct kiocb *, struct socket *,
530                                   struct msghdr *, size_t);
531 static int unix_seqpacket_recvmsg(struct kiocb *, struct socket *,
532                                   struct msghdr *, size_t, int);
533 
534 static int unix_set_peek_off(struct sock *sk, int val)
535 {
536         struct unix_sock *u = unix_sk(sk);
537 
538         if (mutex_lock_interruptible(&u->readlock))
539                 return -EINTR;
540 
541         sk->sk_peek_off = val;
542         mutex_unlock(&u->readlock);
543 
544         return 0;
545 }
546 
547 
548 static const struct proto_ops unix_stream_ops = {
549         .family =       PF_UNIX,
550         .owner =        THIS_MODULE,
551         .release =      unix_release,
552         .bind =         unix_bind,
553         .connect =      unix_stream_connect,
554         .socketpair =   unix_socketpair,
555         .accept =       unix_accept,
556         .getname =      unix_getname,
557         .poll =         unix_poll,
558         .ioctl =        unix_ioctl,
559         .listen =       unix_listen,
560         .shutdown =     unix_shutdown,
561         .setsockopt =   sock_no_setsockopt,
562         .getsockopt =   sock_no_getsockopt,
563         .sendmsg =      unix_stream_sendmsg,
564         .recvmsg =      unix_stream_recvmsg,
565         .mmap =         sock_no_mmap,
566         .sendpage =     sock_no_sendpage,
567         .set_peek_off = unix_set_peek_off,
568 };
569 
570 static const struct proto_ops unix_dgram_ops = {
571         .family =       PF_UNIX,
572         .owner =        THIS_MODULE,
573         .release =      unix_release,
574         .bind =         unix_bind,
575         .connect =      unix_dgram_connect,
576         .socketpair =   unix_socketpair,
577         .accept =       sock_no_accept,
578         .getname =      unix_getname,
579         .poll =         unix_dgram_poll,
580         .ioctl =        unix_ioctl,
581         .listen =       sock_no_listen,
582         .shutdown =     unix_shutdown,
583         .setsockopt =   sock_no_setsockopt,
584         .getsockopt =   sock_no_getsockopt,
585         .sendmsg =      unix_dgram_sendmsg,
586         .recvmsg =      unix_dgram_recvmsg,
587         .mmap =         sock_no_mmap,
588         .sendpage =     sock_no_sendpage,
589         .set_peek_off = unix_set_peek_off,
590 };
591 
592 static const struct proto_ops unix_seqpacket_ops = {
593         .family =       PF_UNIX,
594         .owner =        THIS_MODULE,
595         .release =      unix_release,
596         .bind =         unix_bind,
597         .connect =      unix_stream_connect,
598         .socketpair =   unix_socketpair,
599         .accept =       unix_accept,
600         .getname =      unix_getname,
601         .poll =         unix_dgram_poll,
602         .ioctl =        unix_ioctl,
603         .listen =       unix_listen,
604         .shutdown =     unix_shutdown,
605         .setsockopt =   sock_no_setsockopt,
606         .getsockopt =   sock_no_getsockopt,
607         .sendmsg =      unix_seqpacket_sendmsg,
608         .recvmsg =      unix_seqpacket_recvmsg,
609         .mmap =         sock_no_mmap,
610         .sendpage =     sock_no_sendpage,
611         .set_peek_off = unix_set_peek_off,
612 };
613 
614 static struct proto unix_proto = {
615         .name                   = "UNIX",
616         .owner                  = THIS_MODULE,
617         .obj_size               = sizeof(struct unix_sock),
618 };
619 
620 /*
621  * AF_UNIX sockets do not interact with hardware, hence they
622  * dont trigger interrupts - so it's safe for them to have
623  * bh-unsafe locking for their sk_receive_queue.lock. Split off
624  * this special lock-class by reinitializing the spinlock key:
625  */
626 static struct lock_class_key af_unix_sk_receive_queue_lock_key;
627 
628 static struct sock *unix_create1(struct net *net, struct socket *sock)
629 {
630         struct sock *sk = NULL;
631         struct unix_sock *u;
632 
633         atomic_long_inc(&unix_nr_socks);
634         if (atomic_long_read(&unix_nr_socks) > 2 * get_max_files())
635                 goto out;
636 
637         sk = sk_alloc(net, PF_UNIX, GFP_KERNEL, &unix_proto);
638         if (!sk)
639                 goto out;
640 
641         sock_init_data(sock, sk);
642         lockdep_set_class(&sk->sk_receive_queue.lock,
643                                 &af_unix_sk_receive_queue_lock_key);
644 
645         sk->sk_write_space      = unix_write_space;
646         sk->sk_max_ack_backlog  = net->unx.sysctl_max_dgram_qlen;
647         sk->sk_destruct         = unix_sock_destructor;
648         u         = unix_sk(sk);
649         u->path.dentry = NULL;
650         u->path.mnt = NULL;
651         spin_lock_init(&u->lock);
652         atomic_long_set(&u->inflight, 0);
653         INIT_LIST_HEAD(&u->link);
654         mutex_init(&u->readlock); /* single task reading lock */
655         init_waitqueue_head(&u->peer_wait);
656         unix_insert_socket(unix_sockets_unbound(sk), sk);
657 out:
658         if (sk == NULL)
659                 atomic_long_dec(&unix_nr_socks);
660         else {
661                 local_bh_disable();
662                 sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
663                 local_bh_enable();
664         }
665         return sk;
666 }
667 
668 static int unix_create(struct net *net, struct socket *sock, int protocol,
669                        int kern)
670 {
671         if (protocol && protocol != PF_UNIX)
672                 return -EPROTONOSUPPORT;
673 
674         sock->state = SS_UNCONNECTED;
675 
676         switch (sock->type) {
677         case SOCK_STREAM:
678                 sock->ops = &unix_stream_ops;
679                 break;
680                 /*
681                  *      Believe it or not BSD has AF_UNIX, SOCK_RAW though
682                  *      nothing uses it.
683                  */
684         case SOCK_RAW:
685                 sock->type = SOCK_DGRAM;
686         case SOCK_DGRAM:
687                 sock->ops = &unix_dgram_ops;
688                 break;
689         case SOCK_SEQPACKET:
690                 sock->ops = &unix_seqpacket_ops;
691                 break;
692         default:
693                 return -ESOCKTNOSUPPORT;
694         }
695 
696         return unix_create1(net, sock) ? 0 : -ENOMEM;
697 }
698 
699 static int unix_release(struct socket *sock)
700 {
701         struct sock *sk = sock->sk;
702 
703         if (!sk)
704                 return 0;
705 
706         unix_release_sock(sk, 0);
707         sock->sk = NULL;
708 
709         return 0;
710 }
711 
712 static int unix_autobind(struct socket *sock)
713 {
714         struct sock *sk = sock->sk;
715         struct net *net = sock_net(sk);
716         struct unix_sock *u = unix_sk(sk);
717         static u32 ordernum = 1;
718         struct unix_address *addr;
719         int err;
720         unsigned int retries = 0;
721 
722         err = mutex_lock_interruptible(&u->readlock);
723         if (err)
724                 return err;
725 
726         err = 0;
727         if (u->addr)
728                 goto out;
729 
730         err = -ENOMEM;
731         addr = kzalloc(sizeof(*addr) + sizeof(short) + 16, GFP_KERNEL);
732         if (!addr)
733                 goto out;
734 
735         addr->name->sun_family = AF_UNIX;
736         atomic_set(&addr->refcnt, 1);
737 
738 retry:
739         addr->len = sprintf(addr->name->sun_path+1, "%05x", ordernum) + 1 + sizeof(short);
740         addr->hash = unix_hash_fold(csum_partial(addr->name, addr->len, 0));
741 
742         spin_lock(&unix_table_lock);
743         ordernum = (ordernum+1)&0xFFFFF;
744 
745         if (__unix_find_socket_byname(net, addr->name, addr->len, sock->type,
746                                       addr->hash)) {
747                 spin_unlock(&unix_table_lock);
748                 /*
749                  * __unix_find_socket_byname() may take long time if many names
750                  * are already in use.
751                  */
752                 cond_resched();
753                 /* Give up if all names seems to be in use. */
754                 if (retries++ == 0xFFFFF) {
755                         err = -ENOSPC;
756                         kfree(addr);
757                         goto out;
758                 }
759                 goto retry;
760         }
761         addr->hash ^= sk->sk_type;
762 
763         __unix_remove_socket(sk);
764         u->addr = addr;
765         __unix_insert_socket(&unix_socket_table[addr->hash], sk);
766         spin_unlock(&unix_table_lock);
767         err = 0;
768 
769 out:    mutex_unlock(&u->readlock);
770         return err;
771 }
772 
773 static struct sock *unix_find_other(struct net *net,
774                                     struct sockaddr_un *sunname, int len,
775                                     int type, unsigned int hash, int *error)
776 {
777         struct sock *u;
778         struct path path;
779         int err = 0;
780 
781         if (sunname->sun_path[0]) {
782                 struct inode *inode;
783                 err = kern_path(sunname->sun_path, LOOKUP_FOLLOW, &path);
784                 if (err)
785                         goto fail;
786                 inode = path.dentry->d_inode;
787                 err = inode_permission(inode, MAY_WRITE);
788                 if (err)
789                         goto put_fail;
790 
791                 err = -ECONNREFUSED;
792                 if (!S_ISSOCK(inode->i_mode))
793                         goto put_fail;
794                 u = unix_find_socket_byinode(inode);
795                 if (!u)
796                         goto put_fail;
797 
798                 if (u->sk_type == type)
799                         touch_atime(&path);
800 
801                 path_put(&path);
802 
803                 err = -EPROTOTYPE;
804                 if (u->sk_type != type) {
805                         sock_put(u);
806                         goto fail;
807                 }
808         } else {
809                 err = -ECONNREFUSED;
810                 u = unix_find_socket_byname(net, sunname, len, type, hash);
811                 if (u) {
812                         struct dentry *dentry;
813                         dentry = unix_sk(u)->path.dentry;
814                         if (dentry)
815                                 touch_atime(&unix_sk(u)->path);
816                 } else
817                         goto fail;
818         }
819         return u;
820 
821 put_fail:
822         path_put(&path);
823 fail:
824         *error = err;
825         return NULL;
826 }
827 
828 static int unix_mknod(const char *sun_path, umode_t mode, struct path *res)
829 {
830         struct dentry *dentry;
831         struct path path;
832         int err = 0;
833         /*
834          * Get the parent directory, calculate the hash for last
835          * component.
836          */
837         dentry = kern_path_create(AT_FDCWD, sun_path, &path, 0);
838         err = PTR_ERR(dentry);
839         if (IS_ERR(dentry))
840                 return err;
841 
842         /*
843          * All right, let's create it.
844          */
845         err = security_path_mknod(&path, dentry, mode, 0);
846         if (!err) {
847                 err = vfs_mknod(path.dentry->d_inode, dentry, mode, 0);
848                 if (!err) {
849                         res->mnt = mntget(path.mnt);
850                         res->dentry = dget(dentry);
851                 }
852         }
853         done_path_create(&path, dentry);
854         return err;
855 }
856 
857 static int unix_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
858 {
859         struct sock *sk = sock->sk;
860         struct net *net = sock_net(sk);
861         struct unix_sock *u = unix_sk(sk);
862         struct sockaddr_un *sunaddr = (struct sockaddr_un *)uaddr;
863         char *sun_path = sunaddr->sun_path;
864         int err;
865         unsigned int hash;
866         struct unix_address *addr;
867         struct hlist_head *list;
868 
869         err = -EINVAL;
870         if (sunaddr->sun_family != AF_UNIX)
871                 goto out;
872 
873         if (addr_len == sizeof(short)) {
874                 err = unix_autobind(sock);
875                 goto out;
876         }
877 
878         err = unix_mkname(sunaddr, addr_len, &hash);
879         if (err < 0)
880                 goto out;
881         addr_len = err;
882 
883         err = mutex_lock_interruptible(&u->readlock);
884         if (err)
885                 goto out;
886 
887         err = -EINVAL;
888         if (u->addr)
889                 goto out_up;
890 
891         err = -ENOMEM;
892         addr = kmalloc(sizeof(*addr)+addr_len, GFP_KERNEL);
893         if (!addr)
894                 goto out_up;
895 
896         memcpy(addr->name, sunaddr, addr_len);
897         addr->len = addr_len;
898         addr->hash = hash ^ sk->sk_type;
899         atomic_set(&addr->refcnt, 1);
900 
901         if (sun_path[0]) {
902                 struct path path;
903                 umode_t mode = S_IFSOCK |
904                        (SOCK_INODE(sock)->i_mode & ~current_umask());
905                 err = unix_mknod(sun_path, mode, &path);
906                 if (err) {
907                         if (err == -EEXIST)
908                                 err = -EADDRINUSE;
909                         unix_release_addr(addr);
910                         goto out_up;
911                 }
912                 addr->hash = UNIX_HASH_SIZE;
913                 hash = path.dentry->d_inode->i_ino & (UNIX_HASH_SIZE-1);
914                 spin_lock(&unix_table_lock);
915                 u->path = path;
916                 list = &unix_socket_table[hash];
917         } else {
918                 spin_lock(&unix_table_lock);
919                 err = -EADDRINUSE;
920                 if (__unix_find_socket_byname(net, sunaddr, addr_len,
921                                               sk->sk_type, hash)) {
922                         unix_release_addr(addr);
923                         goto out_unlock;
924                 }
925 
926                 list = &unix_socket_table[addr->hash];
927         }
928 
929         err = 0;
930         __unix_remove_socket(sk);
931         u->addr = addr;
932         __unix_insert_socket(list, sk);
933 
934 out_unlock:
935         spin_unlock(&unix_table_lock);
936 out_up:
937         mutex_unlock(&u->readlock);
938 out:
939         return err;
940 }
941 
942 static void unix_state_double_lock(struct sock *sk1, struct sock *sk2)
943 {
944         if (unlikely(sk1 == sk2) || !sk2) {
945                 unix_state_lock(sk1);
946                 return;
947         }
948         if (sk1 < sk2) {
949                 unix_state_lock(sk1);
950                 unix_state_lock_nested(sk2);
951         } else {
952                 unix_state_lock(sk2);
953                 unix_state_lock_nested(sk1);
954         }
955 }
956 
957 static void unix_state_double_unlock(struct sock *sk1, struct sock *sk2)
958 {
959         if (unlikely(sk1 == sk2) || !sk2) {
960                 unix_state_unlock(sk1);
961                 return;
962         }
963         unix_state_unlock(sk1);
964         unix_state_unlock(sk2);
965 }
966 
967 static int unix_dgram_connect(struct socket *sock, struct sockaddr *addr,
968                               int alen, int flags)
969 {
970         struct sock *sk = sock->sk;
971         struct net *net = sock_net(sk);
972         struct sockaddr_un *sunaddr = (struct sockaddr_un *)addr;
973         struct sock *other;
974         unsigned int hash;
975         int err;
976 
977         if (addr->sa_family != AF_UNSPEC) {
978                 err = unix_mkname(sunaddr, alen, &hash);
979                 if (err < 0)
980                         goto out;
981                 alen = err;
982 
983                 if (test_bit(SOCK_PASSCRED, &sock->flags) &&
984                     !unix_sk(sk)->addr && (err = unix_autobind(sock)) != 0)
985                         goto out;
986 
987 restart:
988                 other = unix_find_other(net, sunaddr, alen, sock->type, hash, &err);
989                 if (!other)
990                         goto out;
991 
992                 unix_state_double_lock(sk, other);
993 
994                 /* Apparently VFS overslept socket death. Retry. */
995                 if (sock_flag(other, SOCK_DEAD)) {
996                         unix_state_double_unlock(sk, other);
997                         sock_put(other);
998                         goto restart;
999                 }
1000 
1001                 err = -EPERM;
1002                 if (!unix_may_send(sk, other))
1003                         goto out_unlock;
1004 
1005                 err = security_unix_may_send(sk->sk_socket, other->sk_socket);
1006                 if (err)
1007                         goto out_unlock;
1008 
1009         } else {
1010                 /*
1011                  *      1003.1g breaking connected state with AF_UNSPEC
1012                  */
1013                 other = NULL;
1014                 unix_state_double_lock(sk, other);
1015         }
1016 
1017         /*
1018          * If it was connected, reconnect.
1019          */
1020         if (unix_peer(sk)) {
1021                 struct sock *old_peer = unix_peer(sk);
1022                 unix_peer(sk) = other;
1023                 unix_state_double_unlock(sk, other);
1024 
1025                 if (other != old_peer)
1026                         unix_dgram_disconnected(sk, old_peer);
1027                 sock_put(old_peer);
1028         } else {
1029                 unix_peer(sk) = other;
1030                 unix_state_double_unlock(sk, other);
1031         }
1032         return 0;
1033 
1034 out_unlock:
1035         unix_state_double_unlock(sk, other);
1036         sock_put(other);
1037 out:
1038         return err;
1039 }
1040 
1041 static long unix_wait_for_peer(struct sock *other, long timeo)
1042 {
1043         struct unix_sock *u = unix_sk(other);
1044         int sched;
1045         DEFINE_WAIT(wait);
1046 
1047         prepare_to_wait_exclusive(&u->peer_wait, &wait, TASK_INTERRUPTIBLE);
1048 
1049         sched = !sock_flag(other, SOCK_DEAD) &&
1050                 !(other->sk_shutdown & RCV_SHUTDOWN) &&
1051                 unix_recvq_full(other);
1052 
1053         unix_state_unlock(other);
1054 
1055         if (sched)
1056                 timeo = schedule_timeout(timeo);
1057 
1058         finish_wait(&u->peer_wait, &wait);
1059         return timeo;
1060 }
1061 
1062 static int unix_stream_connect(struct socket *sock, struct sockaddr *uaddr,
1063                                int addr_len, int flags)
1064 {
1065         struct sockaddr_un *sunaddr = (struct sockaddr_un *)uaddr;
1066         struct sock *sk = sock->sk;
1067         struct net *net = sock_net(sk);
1068         struct unix_sock *u = unix_sk(sk), *newu, *otheru;
1069         struct sock *newsk = NULL;
1070         struct sock *other = NULL;
1071         struct sk_buff *skb = NULL;
1072         unsigned int hash;
1073         int st;
1074         int err;
1075         long timeo;
1076 
1077         err = unix_mkname(sunaddr, addr_len, &hash);
1078         if (err < 0)
1079                 goto out;
1080         addr_len = err;
1081 
1082         if (test_bit(SOCK_PASSCRED, &sock->flags) && !u->addr &&
1083             (err = unix_autobind(sock)) != 0)
1084                 goto out;
1085 
1086         timeo = sock_sndtimeo(sk, flags & O_NONBLOCK);
1087 
1088         /* First of all allocate resources.
1089            If we will make it after state is locked,
1090            we will have to recheck all again in any case.
1091          */
1092 
1093         err = -ENOMEM;
1094 
1095         /* create new sock for complete connection */
1096         newsk = unix_create1(sock_net(sk), NULL);
1097         if (newsk == NULL)
1098                 goto out;
1099 
1100         /* Allocate skb for sending to listening sock */
1101         skb = sock_wmalloc(newsk, 1, 0, GFP_KERNEL);
1102         if (skb == NULL)
1103                 goto out;
1104 
1105 restart:
1106         /*  Find listening sock. */
1107         other = unix_find_other(net, sunaddr, addr_len, sk->sk_type, hash, &err);
1108         if (!other)
1109                 goto out;
1110 
1111         /* Latch state of peer */
1112         unix_state_lock(other);
1113 
1114         /* Apparently VFS overslept socket death. Retry. */
1115         if (sock_flag(other, SOCK_DEAD)) {
1116                 unix_state_unlock(other);
1117                 sock_put(other);
1118                 goto restart;
1119         }
1120 
1121         err = -ECONNREFUSED;
1122         if (other->sk_state != TCP_LISTEN)
1123                 goto out_unlock;
1124         if (other->sk_shutdown & RCV_SHUTDOWN)
1125                 goto out_unlock;
1126 
1127         if (unix_recvq_full(other)) {
1128                 err = -EAGAIN;
1129                 if (!timeo)
1130                         goto out_unlock;
1131 
1132                 timeo = unix_wait_for_peer(other, timeo);
1133 
1134                 err = sock_intr_errno(timeo);
1135                 if (signal_pending(current))
1136                         goto out;
1137                 sock_put(other);
1138                 goto restart;
1139         }
1140 
1141         /* Latch our state.
1142 
1143            It is tricky place. We need to grab our state lock and cannot
1144            drop lock on peer. It is dangerous because deadlock is
1145            possible. Connect to self case and simultaneous
1146            attempt to connect are eliminated by checking socket
1147            state. other is TCP_LISTEN, if sk is TCP_LISTEN we
1148            check this before attempt to grab lock.
1149 
1150            Well, and we have to recheck the state after socket locked.
1151          */
1152         st = sk->sk_state;
1153 
1154         switch (st) {
1155         case TCP_CLOSE:
1156                 /* This is ok... continue with connect */
1157                 break;
1158         case TCP_ESTABLISHED:
1159                 /* Socket is already connected */
1160                 err = -EISCONN;
1161                 goto out_unlock;
1162         default:
1163                 err = -EINVAL;
1164                 goto out_unlock;
1165         }
1166 
1167         unix_state_lock_nested(sk);
1168 
1169         if (sk->sk_state != st) {
1170                 unix_state_unlock(sk);
1171                 unix_state_unlock(other);
1172                 sock_put(other);
1173                 goto restart;
1174         }
1175 
1176         err = security_unix_stream_connect(sk, other, newsk);
1177         if (err) {
1178                 unix_state_unlock(sk);
1179                 goto out_unlock;
1180         }
1181 
1182         /* The way is open! Fastly set all the necessary fields... */
1183 
1184         sock_hold(sk);
1185         unix_peer(newsk)        = sk;
1186         newsk->sk_state         = TCP_ESTABLISHED;
1187         newsk->sk_type          = sk->sk_type;
1188         init_peercred(newsk);
1189         newu = unix_sk(newsk);
1190         RCU_INIT_POINTER(newsk->sk_wq, &newu->peer_wq);
1191         otheru = unix_sk(other);
1192 
1193         /* copy address information from listening to new sock*/
1194         if (otheru->addr) {
1195                 atomic_inc(&otheru->addr->refcnt);
1196                 newu->addr = otheru->addr;
1197         }
1198         if (otheru->path.dentry) {
1199                 path_get(&otheru->path);
1200                 newu->path = otheru->path;
1201         }
1202 
1203         /* Set credentials */
1204         copy_peercred(sk, other);
1205 
1206         sock->state     = SS_CONNECTED;
1207         sk->sk_state    = TCP_ESTABLISHED;
1208         sock_hold(newsk);
1209 
1210         smp_mb__after_atomic(); /* sock_hold() does an atomic_inc() */
1211         unix_peer(sk)   = newsk;
1212 
1213         unix_state_unlock(sk);
1214 
1215         /* take ten and and send info to listening sock */
1216         spin_lock(&other->sk_receive_queue.lock);
1217         __skb_queue_tail(&other->sk_receive_queue, skb);
1218         spin_unlock(&other->sk_receive_queue.lock);
1219         unix_state_unlock(other);
1220         other->sk_data_ready(other);
1221         sock_put(other);
1222         return 0;
1223 
1224 out_unlock:
1225         if (other)
1226                 unix_state_unlock(other);
1227 
1228 out:
1229         kfree_skb(skb);
1230         if (newsk)
1231                 unix_release_sock(newsk, 0);
1232         if (other)
1233                 sock_put(other);
1234         return err;
1235 }
1236 
1237 static int unix_socketpair(struct socket *socka, struct socket *sockb)
1238 {
1239         struct sock *ska = socka->sk, *skb = sockb->sk;
1240 
1241         /* Join our sockets back to back */
1242         sock_hold(ska);
1243         sock_hold(skb);
1244         unix_peer(ska) = skb;
1245         unix_peer(skb) = ska;
1246         init_peercred(ska);
1247         init_peercred(skb);
1248 
1249         if (ska->sk_type != SOCK_DGRAM) {
1250                 ska->sk_state = TCP_ESTABLISHED;
1251                 skb->sk_state = TCP_ESTABLISHED;
1252                 socka->state  = SS_CONNECTED;
1253                 sockb->state  = SS_CONNECTED;
1254         }
1255         return 0;
1256 }
1257 
1258 static void unix_sock_inherit_flags(const struct socket *old,
1259                                     struct socket *new)
1260 {
1261         if (test_bit(SOCK_PASSCRED, &old->flags))
1262                 set_bit(SOCK_PASSCRED, &new->flags);
1263         if (test_bit(SOCK_PASSSEC, &old->flags))
1264                 set_bit(SOCK_PASSSEC, &new->flags);
1265 }
1266 
1267 static int unix_accept(struct socket *sock, struct socket *newsock, int flags)
1268 {
1269         struct sock *sk = sock->sk;
1270         struct sock *tsk;
1271         struct sk_buff *skb;
1272         int err;
1273 
1274         err = -EOPNOTSUPP;
1275         if (sock->type != SOCK_STREAM && sock->type != SOCK_SEQPACKET)
1276                 goto out;
1277 
1278         err = -EINVAL;
1279         if (sk->sk_state != TCP_LISTEN)
1280                 goto out;
1281 
1282         /* If socket state is TCP_LISTEN it cannot change (for now...),
1283          * so that no locks are necessary.
1284          */
1285 
1286         skb = skb_recv_datagram(sk, 0, flags&O_NONBLOCK, &err);
1287         if (!skb) {
1288                 /* This means receive shutdown. */
1289                 if (err == 0)
1290                         err = -EINVAL;
1291                 goto out;
1292         }
1293 
1294         tsk = skb->sk;
1295         skb_free_datagram(sk, skb);
1296         wake_up_interruptible(&unix_sk(sk)->peer_wait);
1297 
1298         /* attach accepted sock to socket */
1299         unix_state_lock(tsk);
1300         newsock->state = SS_CONNECTED;
1301         unix_sock_inherit_flags(sock, newsock);
1302         sock_graft(tsk, newsock);
1303         unix_state_unlock(tsk);
1304         return 0;
1305 
1306 out:
1307         return err;
1308 }
1309 
1310 
1311 static int unix_getname(struct socket *sock, struct sockaddr *uaddr, int *uaddr_len, int peer)
1312 {
1313         struct sock *sk = sock->sk;
1314         struct unix_sock *u;
1315         DECLARE_SOCKADDR(struct sockaddr_un *, sunaddr, uaddr);
1316         int err = 0;
1317 
1318         if (peer) {
1319                 sk = unix_peer_get(sk);
1320 
1321                 err = -ENOTCONN;
1322                 if (!sk)
1323                         goto out;
1324                 err = 0;
1325         } else {
1326                 sock_hold(sk);
1327         }
1328 
1329         u = unix_sk(sk);
1330         unix_state_lock(sk);
1331         if (!u->addr) {
1332                 sunaddr->sun_family = AF_UNIX;
1333                 sunaddr->sun_path[0] = 0;
1334                 *uaddr_len = sizeof(short);
1335         } else {
1336                 struct unix_address *addr = u->addr;
1337 
1338                 *uaddr_len = addr->len;
1339                 memcpy(sunaddr, addr->name, *uaddr_len);
1340         }
1341         unix_state_unlock(sk);
1342         sock_put(sk);
1343 out:
1344         return err;
1345 }
1346 
1347 static void unix_detach_fds(struct scm_cookie *scm, struct sk_buff *skb)
1348 {
1349         int i;
1350 
1351         scm->fp = UNIXCB(skb).fp;
1352         UNIXCB(skb).fp = NULL;
1353 
1354         for (i = scm->fp->count-1; i >= 0; i--)
1355                 unix_notinflight(scm->fp->fp[i]);
1356 }
1357 
1358 static void unix_destruct_scm(struct sk_buff *skb)
1359 {
1360         struct scm_cookie scm;
1361         memset(&scm, 0, sizeof(scm));
1362         scm.pid  = UNIXCB(skb).pid;
1363         if (UNIXCB(skb).fp)
1364                 unix_detach_fds(&scm, skb);
1365 
1366         /* Alas, it calls VFS */
1367         /* So fscking what? fput() had been SMP-safe since the last Summer */
1368         scm_destroy(&scm);
1369         sock_wfree(skb);
1370 }
1371 
1372 #define MAX_RECURSION_LEVEL 4
1373 
1374 static int unix_attach_fds(struct scm_cookie *scm, struct sk_buff *skb)
1375 {
1376         int i;
1377         unsigned char max_level = 0;
1378         int unix_sock_count = 0;
1379 
1380         for (i = scm->fp->count - 1; i >= 0; i--) {
1381                 struct sock *sk = unix_get_socket(scm->fp->fp[i]);
1382 
1383                 if (sk) {
1384                         unix_sock_count++;
1385                         max_level = max(max_level,
1386                                         unix_sk(sk)->recursion_level);
1387                 }
1388         }
1389         if (unlikely(max_level > MAX_RECURSION_LEVEL))
1390                 return -ETOOMANYREFS;
1391 
1392         /*
1393          * Need to duplicate file references for the sake of garbage
1394          * collection.  Otherwise a socket in the fps might become a
1395          * candidate for GC while the skb is not yet queued.
1396          */
1397         UNIXCB(skb).fp = scm_fp_dup(scm->fp);
1398         if (!UNIXCB(skb).fp)
1399                 return -ENOMEM;
1400 
1401         if (unix_sock_count) {
1402                 for (i = scm->fp->count - 1; i >= 0; i--)
1403                         unix_inflight(scm->fp->fp[i]);
1404         }
1405         return max_level;
1406 }
1407 
1408 static int unix_scm_to_skb(struct scm_cookie *scm, struct sk_buff *skb, bool send_fds)
1409 {
1410         int err = 0;
1411 
1412         UNIXCB(skb).pid  = get_pid(scm->pid);
1413         UNIXCB(skb).uid = scm->creds.uid;
1414         UNIXCB(skb).gid = scm->creds.gid;
1415         UNIXCB(skb).fp = NULL;
1416         if (scm->fp && send_fds)
1417                 err = unix_attach_fds(scm, skb);
1418 
1419         skb->destructor = unix_destruct_scm;
1420         return err;
1421 }
1422 
1423 /*
1424  * Some apps rely on write() giving SCM_CREDENTIALS
1425  * We include credentials if source or destination socket
1426  * asserted SOCK_PASSCRED.
1427  */
1428 static void maybe_add_creds(struct sk_buff *skb, const struct socket *sock,
1429                             const struct sock *other)
1430 {
1431         if (UNIXCB(skb).pid)
1432                 return;
1433         if (test_bit(SOCK_PASSCRED, &sock->flags) ||
1434             !other->sk_socket ||
1435             test_bit(SOCK_PASSCRED, &other->sk_socket->flags)) {
1436                 UNIXCB(skb).pid  = get_pid(task_tgid(current));
1437                 current_uid_gid(&UNIXCB(skb).uid, &UNIXCB(skb).gid);
1438         }
1439 }
1440 
1441 /*
1442  *      Send AF_UNIX data.
1443  */
1444 
1445 static int unix_dgram_sendmsg(struct kiocb *kiocb, struct socket *sock,
1446                               struct msghdr *msg, size_t len)
1447 {
1448         struct sock *sk = sock->sk;
1449         struct net *net = sock_net(sk);
1450         struct unix_sock *u = unix_sk(sk);
1451         DECLARE_SOCKADDR(struct sockaddr_un *, sunaddr, msg->msg_name);
1452         struct sock *other = NULL;
1453         int namelen = 0; /* fake GCC */
1454         int err;
1455         unsigned int hash;
1456         struct sk_buff *skb;
1457         long timeo;
1458         struct scm_cookie scm;
1459         int max_level;
1460         int data_len = 0;
1461 
1462         wait_for_unix_gc();
1463         err = scm_send(sock, msg, &scm, false);
1464         if (err < 0)
1465                 return err;
1466 
1467         err = -EOPNOTSUPP;
1468         if (msg->msg_flags&MSG_OOB)
1469                 goto out;
1470 
1471         if (msg->msg_namelen) {
1472                 err = unix_mkname(sunaddr, msg->msg_namelen, &hash);
1473                 if (err < 0)
1474                         goto out;
1475                 namelen = err;
1476         } else {
1477                 sunaddr = NULL;
1478                 err = -ENOTCONN;
1479                 other = unix_peer_get(sk);
1480                 if (!other)
1481                         goto out;
1482         }
1483 
1484         if (test_bit(SOCK_PASSCRED, &sock->flags) && !u->addr
1485             && (err = unix_autobind(sock)) != 0)
1486                 goto out;
1487 
1488         err = -EMSGSIZE;
1489         if (len > sk->sk_sndbuf - 32)
1490                 goto out;
1491 
1492         if (len > SKB_MAX_ALLOC) {
1493                 data_len = min_t(size_t,
1494                                  len - SKB_MAX_ALLOC,
1495                                  MAX_SKB_FRAGS * PAGE_SIZE);
1496                 data_len = PAGE_ALIGN(data_len);
1497 
1498                 BUILD_BUG_ON(SKB_MAX_ALLOC < PAGE_SIZE);
1499         }
1500 
1501         skb = sock_alloc_send_pskb(sk, len - data_len, data_len,
1502                                    msg->msg_flags & MSG_DONTWAIT, &err,
1503                                    PAGE_ALLOC_COSTLY_ORDER);
1504         if (skb == NULL)
1505                 goto out;
1506 
1507         err = unix_scm_to_skb(&scm, skb, true);
1508         if (err < 0)
1509                 goto out_free;
1510         max_level = err + 1;
1511         unix_get_secdata(&scm, skb);
1512 
1513         skb_put(skb, len - data_len);
1514         skb->data_len = data_len;
1515         skb->len = len;
1516         err = skb_copy_datagram_from_iter(skb, 0, &msg->msg_iter, len);
1517         if (err)
1518                 goto out_free;
1519 
1520         timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT);
1521 
1522 restart:
1523         if (!other) {
1524                 err = -ECONNRESET;
1525                 if (sunaddr == NULL)
1526                         goto out_free;
1527 
1528                 other = unix_find_other(net, sunaddr, namelen, sk->sk_type,
1529                                         hash, &err);
1530                 if (other == NULL)
1531                         goto out_free;
1532         }
1533 
1534         if (sk_filter(other, skb) < 0) {
1535                 /* Toss the packet but do not return any error to the sender */
1536                 err = len;
1537                 goto out_free;
1538         }
1539 
1540         unix_state_lock(other);
1541         err = -EPERM;
1542         if (!unix_may_send(sk, other))
1543                 goto out_unlock;
1544 
1545         if (sock_flag(other, SOCK_DEAD)) {
1546                 /*
1547                  *      Check with 1003.1g - what should
1548                  *      datagram error
1549                  */
1550                 unix_state_unlock(other);
1551                 sock_put(other);
1552 
1553                 err = 0;
1554                 unix_state_lock(sk);
1555                 if (unix_peer(sk) == other) {
1556                         unix_peer(sk) = NULL;
1557                         unix_state_unlock(sk);
1558 
1559                         unix_dgram_disconnected(sk, other);
1560                         sock_put(other);
1561                         err = -ECONNREFUSED;
1562                 } else {
1563                         unix_state_unlock(sk);
1564                 }
1565 
1566                 other = NULL;
1567                 if (err)
1568                         goto out_free;
1569                 goto restart;
1570         }
1571 
1572         err = -EPIPE;
1573         if (other->sk_shutdown & RCV_SHUTDOWN)
1574                 goto out_unlock;
1575 
1576         if (sk->sk_type != SOCK_SEQPACKET) {
1577                 err = security_unix_may_send(sk->sk_socket, other->sk_socket);
1578                 if (err)
1579                         goto out_unlock;
1580         }
1581 
1582         if (unix_peer(other) != sk && unix_recvq_full(other)) {
1583                 if (!timeo) {
1584                         err = -EAGAIN;
1585                         goto out_unlock;
1586                 }
1587 
1588                 timeo = unix_wait_for_peer(other, timeo);
1589 
1590                 err = sock_intr_errno(timeo);
1591                 if (signal_pending(current))
1592                         goto out_free;
1593 
1594                 goto restart;
1595         }
1596 
1597         if (sock_flag(other, SOCK_RCVTSTAMP))
1598                 __net_timestamp(skb);
1599         maybe_add_creds(skb, sock, other);
1600         skb_queue_tail(&other->sk_receive_queue, skb);
1601         if (max_level > unix_sk(other)->recursion_level)
1602                 unix_sk(other)->recursion_level = max_level;
1603         unix_state_unlock(other);
1604         other->sk_data_ready(other);
1605         sock_put(other);
1606         scm_destroy(&scm);
1607         return len;
1608 
1609 out_unlock:
1610         unix_state_unlock(other);
1611 out_free:
1612         kfree_skb(skb);
1613 out:
1614         if (other)
1615                 sock_put(other);
1616         scm_destroy(&scm);
1617         return err;
1618 }
1619 
1620 /* We use paged skbs for stream sockets, and limit occupancy to 32768
1621  * bytes, and a minimun of a full page.
1622  */
1623 #define UNIX_SKB_FRAGS_SZ (PAGE_SIZE << get_order(32768))
1624 
1625 static int unix_stream_sendmsg(struct kiocb *kiocb, struct socket *sock,
1626                                struct msghdr *msg, size_t len)
1627 {
1628         struct sock *sk = sock->sk;
1629         struct sock *other = NULL;
1630         int err, size;
1631         struct sk_buff *skb;
1632         int sent = 0;
1633         struct scm_cookie scm;
1634         bool fds_sent = false;
1635         int max_level;
1636         int data_len;
1637 
1638         wait_for_unix_gc();
1639         err = scm_send(sock, msg, &scm, false);
1640         if (err < 0)
1641                 return err;
1642 
1643         err = -EOPNOTSUPP;
1644         if (msg->msg_flags&MSG_OOB)
1645                 goto out_err;
1646 
1647         if (msg->msg_namelen) {
1648                 err = sk->sk_state == TCP_ESTABLISHED ? -EISCONN : -EOPNOTSUPP;
1649                 goto out_err;
1650         } else {
1651                 err = -ENOTCONN;
1652                 other = unix_peer(sk);
1653                 if (!other)
1654                         goto out_err;
1655         }
1656 
1657         if (sk->sk_shutdown & SEND_SHUTDOWN)
1658                 goto pipe_err;
1659 
1660         while (sent < len) {
1661                 size = len - sent;
1662 
1663                 /* Keep two messages in the pipe so it schedules better */
1664                 size = min_t(int, size, (sk->sk_sndbuf >> 1) - 64);
1665 
1666                 /* allow fallback to order-0 allocations */
1667                 size = min_t(int, size, SKB_MAX_HEAD(0) + UNIX_SKB_FRAGS_SZ);
1668 
1669                 data_len = max_t(int, 0, size - SKB_MAX_HEAD(0));
1670 
1671                 data_len = min_t(size_t, size, PAGE_ALIGN(data_len));
1672 
1673                 skb = sock_alloc_send_pskb(sk, size - data_len, data_len,
1674                                            msg->msg_flags & MSG_DONTWAIT, &err,
1675                                            get_order(UNIX_SKB_FRAGS_SZ));
1676                 if (!skb)
1677                         goto out_err;
1678 
1679                 /* Only send the fds in the first buffer */
1680                 err = unix_scm_to_skb(&scm, skb, !fds_sent);
1681                 if (err < 0) {
1682                         kfree_skb(skb);
1683                         goto out_err;
1684                 }
1685                 max_level = err + 1;
1686                 fds_sent = true;
1687 
1688                 skb_put(skb, size - data_len);
1689                 skb->data_len = data_len;
1690                 skb->len = size;
1691                 err = skb_copy_datagram_from_iter(skb, 0, &msg->msg_iter, size);
1692                 if (err) {
1693                         kfree_skb(skb);
1694                         goto out_err;
1695                 }
1696 
1697                 unix_state_lock(other);
1698 
1699                 if (sock_flag(other, SOCK_DEAD) ||
1700                     (other->sk_shutdown & RCV_SHUTDOWN))
1701                         goto pipe_err_free;
1702 
1703                 maybe_add_creds(skb, sock, other);
1704                 skb_queue_tail(&other->sk_receive_queue, skb);
1705                 if (max_level > unix_sk(other)->recursion_level)
1706                         unix_sk(other)->recursion_level = max_level;
1707                 unix_state_unlock(other);
1708                 other->sk_data_ready(other);
1709                 sent += size;
1710         }
1711 
1712         scm_destroy(&scm);
1713 
1714         return sent;
1715 
1716 pipe_err_free:
1717         unix_state_unlock(other);
1718         kfree_skb(skb);
1719 pipe_err:
1720         if (sent == 0 && !(msg->msg_flags&MSG_NOSIGNAL))
1721                 send_sig(SIGPIPE, current, 0);
1722         err = -EPIPE;
1723 out_err:
1724         scm_destroy(&scm);
1725         return sent ? : err;
1726 }
1727 
1728 static int unix_seqpacket_sendmsg(struct kiocb *kiocb, struct socket *sock,
1729                                   struct msghdr *msg, size_t len)
1730 {
1731         int err;
1732         struct sock *sk = sock->sk;
1733 
1734         err = sock_error(sk);
1735         if (err)
1736                 return err;
1737 
1738         if (sk->sk_state != TCP_ESTABLISHED)
1739                 return -ENOTCONN;
1740 
1741         if (msg->msg_namelen)
1742                 msg->msg_namelen = 0;
1743 
1744         return unix_dgram_sendmsg(kiocb, sock, msg, len);
1745 }
1746 
1747 static int unix_seqpacket_recvmsg(struct kiocb *iocb, struct socket *sock,
1748                               struct msghdr *msg, size_t size,
1749                               int flags)
1750 {
1751         struct sock *sk = sock->sk;
1752 
1753         if (sk->sk_state != TCP_ESTABLISHED)
1754                 return -ENOTCONN;
1755 
1756         return unix_dgram_recvmsg(iocb, sock, msg, size, flags);
1757 }
1758 
1759 static void unix_copy_addr(struct msghdr *msg, struct sock *sk)
1760 {
1761         struct unix_sock *u = unix_sk(sk);
1762 
1763         if (u->addr) {
1764                 msg->msg_namelen = u->addr->len;
1765                 memcpy(msg->msg_name, u->addr->name, u->addr->len);
1766         }
1767 }
1768 
1769 static int unix_dgram_recvmsg(struct kiocb *iocb, struct socket *sock,
1770                               struct msghdr *msg, size_t size,
1771                               int flags)
1772 {
1773         struct scm_cookie scm;
1774         struct sock *sk = sock->sk;
1775         struct unix_sock *u = unix_sk(sk);
1776         int noblock = flags & MSG_DONTWAIT;
1777         struct sk_buff *skb;
1778         int err;
1779         int peeked, skip;
1780 
1781         err = -EOPNOTSUPP;
1782         if (flags&MSG_OOB)
1783                 goto out;
1784 
1785         err = mutex_lock_interruptible(&u->readlock);
1786         if (unlikely(err)) {
1787                 /* recvmsg() in non blocking mode is supposed to return -EAGAIN
1788                  * sk_rcvtimeo is not honored by mutex_lock_interruptible()
1789                  */
1790                 err = noblock ? -EAGAIN : -ERESTARTSYS;
1791                 goto out;
1792         }
1793 
1794         skip = sk_peek_offset(sk, flags);
1795 
1796         skb = __skb_recv_datagram(sk, flags, &peeked, &skip, &err);
1797         if (!skb) {
1798                 unix_state_lock(sk);
1799                 /* Signal EOF on disconnected non-blocking SEQPACKET socket. */
1800                 if (sk->sk_type == SOCK_SEQPACKET && err == -EAGAIN &&
1801                     (sk->sk_shutdown & RCV_SHUTDOWN))
1802                         err = 0;
1803                 unix_state_unlock(sk);
1804                 goto out_unlock;
1805         }
1806 
1807         wake_up_interruptible_sync_poll(&u->peer_wait,
1808                                         POLLOUT | POLLWRNORM | POLLWRBAND);
1809 
1810         if (ccs_socket_post_recvmsg_permission(sk, skb, flags)) {
1811                 err = -EAGAIN; /* Hope less harmful than -EPERM. */
1812                 goto out_unlock;
1813         }
1814         if (msg->msg_name)
1815                 unix_copy_addr(msg, skb->sk);
1816 
1817         if (size > skb->len - skip)
1818                 size = skb->len - skip;
1819         else if (size < skb->len - skip)
1820                 msg->msg_flags |= MSG_TRUNC;
1821 
1822         err = skb_copy_datagram_msg(skb, skip, msg, size);
1823         if (err)
1824                 goto out_free;
1825 
1826         if (sock_flag(sk, SOCK_RCVTSTAMP))
1827                 __sock_recv_timestamp(msg, sk, skb);
1828 
1829         memset(&scm, 0, sizeof(scm));
1830 
1831         scm_set_cred(&scm, UNIXCB(skb).pid, UNIXCB(skb).uid, UNIXCB(skb).gid);
1832         unix_set_secdata(&scm, skb);
1833 
1834         if (!(flags & MSG_PEEK)) {
1835                 if (UNIXCB(skb).fp)
1836                         unix_detach_fds(&scm, skb);
1837 
1838                 sk_peek_offset_bwd(sk, skb->len);
1839         } else {
1840                 /* It is questionable: on PEEK we could:
1841                    - do not return fds - good, but too simple 8)
1842                    - return fds, and do not return them on read (old strategy,
1843                      apparently wrong)
1844                    - clone fds (I chose it for now, it is the most universal
1845                      solution)
1846 
1847                    POSIX 1003.1g does not actually define this clearly
1848                    at all. POSIX 1003.1g doesn't define a lot of things
1849                    clearly however!
1850 
1851                 */
1852 
1853                 sk_peek_offset_fwd(sk, size);
1854 
1855                 if (UNIXCB(skb).fp)
1856                         scm.fp = scm_fp_dup(UNIXCB(skb).fp);
1857         }
1858         err = (flags & MSG_TRUNC) ? skb->len - skip : size;
1859 
1860         scm_recv(sock, msg, &scm, flags);
1861 
1862 out_free:
1863         skb_free_datagram(sk, skb);
1864 out_unlock:
1865         mutex_unlock(&u->readlock);
1866 out:
1867         return err;
1868 }
1869 
1870 /*
1871  *      Sleep until more data has arrived. But check for races..
1872  */
1873 static long unix_stream_data_wait(struct sock *sk, long timeo,
1874                                   struct sk_buff *last)
1875 {
1876         DEFINE_WAIT(wait);
1877 
1878         unix_state_lock(sk);
1879 
1880         for (;;) {
1881                 prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
1882 
1883                 if (skb_peek_tail(&sk->sk_receive_queue) != last ||
1884                     sk->sk_err ||
1885                     (sk->sk_shutdown & RCV_SHUTDOWN) ||
1886                     signal_pending(current) ||
1887                     !timeo)
1888                         break;
1889 
1890                 set_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags);
1891                 unix_state_unlock(sk);
1892                 timeo = freezable_schedule_timeout(timeo);
1893                 unix_state_lock(sk);
1894 
1895                 if (sock_flag(sk, SOCK_DEAD))
1896                         break;
1897 
1898                 clear_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags);
1899         }
1900 
1901         finish_wait(sk_sleep(sk), &wait);
1902         unix_state_unlock(sk);
1903         return timeo;
1904 }
1905 
1906 static unsigned int unix_skb_len(const struct sk_buff *skb)
1907 {
1908         return skb->len - UNIXCB(skb).consumed;
1909 }
1910 
1911 static int unix_stream_recvmsg(struct kiocb *iocb, struct socket *sock,
1912                                struct msghdr *msg, size_t size,
1913                                int flags)
1914 {
1915         struct scm_cookie scm;
1916         struct sock *sk = sock->sk;
1917         struct unix_sock *u = unix_sk(sk);
1918         DECLARE_SOCKADDR(struct sockaddr_un *, sunaddr, msg->msg_name);
1919         int copied = 0;
1920         int noblock = flags & MSG_DONTWAIT;
1921         int check_creds = 0;
1922         int target;
1923         int err = 0;
1924         long timeo;
1925         int skip;
1926 
1927         err = -EINVAL;
1928         if (sk->sk_state != TCP_ESTABLISHED)
1929                 goto out;
1930 
1931         err = -EOPNOTSUPP;
1932         if (flags&MSG_OOB)
1933                 goto out;
1934 
1935         target = sock_rcvlowat(sk, flags&MSG_WAITALL, size);
1936         timeo = sock_rcvtimeo(sk, noblock);
1937 
1938         /* Lock the socket to prevent queue disordering
1939          * while sleeps in memcpy_tomsg
1940          */
1941 
1942         memset(&scm, 0, sizeof(scm));
1943 
1944         err = mutex_lock_interruptible(&u->readlock);
1945         if (unlikely(err)) {
1946                 /* recvmsg() in non blocking mode is supposed to return -EAGAIN
1947                  * sk_rcvtimeo is not honored by mutex_lock_interruptible()
1948                  */
1949                 err = noblock ? -EAGAIN : -ERESTARTSYS;
1950                 goto out;
1951         }
1952 
1953         do {
1954                 int chunk;
1955                 struct sk_buff *skb, *last;
1956 
1957                 unix_state_lock(sk);
1958                 if (sock_flag(sk, SOCK_DEAD)) {
1959                         err = -ECONNRESET;
1960                         goto unlock;
1961                 }
1962                 last = skb = skb_peek(&sk->sk_receive_queue);
1963 again:
1964                 if (skb == NULL) {
1965                         unix_sk(sk)->recursion_level = 0;
1966                         if (copied >= target)
1967                                 goto unlock;
1968 
1969                         /*
1970                          *      POSIX 1003.1g mandates this order.
1971                          */
1972 
1973                         err = sock_error(sk);
1974                         if (err)
1975                                 goto unlock;
1976                         if (sk->sk_shutdown & RCV_SHUTDOWN)
1977                                 goto unlock;
1978 
1979                         unix_state_unlock(sk);
1980                         err = -EAGAIN;
1981                         if (!timeo)
1982                                 break;
1983                         mutex_unlock(&u->readlock);
1984 
1985                         timeo = unix_stream_data_wait(sk, timeo, last);
1986 
1987                         if (signal_pending(current)
1988                             ||  mutex_lock_interruptible(&u->readlock)) {
1989                                 err = sock_intr_errno(timeo);
1990                                 goto out;
1991                         }
1992 
1993                         continue;
1994  unlock:
1995                         unix_state_unlock(sk);
1996                         break;
1997                 }
1998 
1999                 skip = sk_peek_offset(sk, flags);
2000                 while (skip >= unix_skb_len(skb)) {
2001                         skip -= unix_skb_len(skb);
2002                         last = skb;
2003                         skb = skb_peek_next(skb, &sk->sk_receive_queue);
2004                         if (!skb)
2005                                 goto again;
2006                 }
2007 
2008                 unix_state_unlock(sk);
2009 
2010                 if (check_creds) {
2011                         /* Never glue messages from different writers */
2012                         if ((UNIXCB(skb).pid  != scm.pid) ||
2013                             !uid_eq(UNIXCB(skb).uid, scm.creds.uid) ||
2014                             !gid_eq(UNIXCB(skb).gid, scm.creds.gid))
2015                                 break;
2016                 } else if (test_bit(SOCK_PASSCRED, &sock->flags)) {
2017                         /* Copy credentials */
2018                         scm_set_cred(&scm, UNIXCB(skb).pid, UNIXCB(skb).uid, UNIXCB(skb).gid);
2019                         check_creds = 1;
2020                 }
2021 
2022                 /* Copy address just once */
2023                 if (sunaddr) {
2024                         unix_copy_addr(msg, skb->sk);
2025                         sunaddr = NULL;
2026                 }
2027 
2028                 chunk = min_t(unsigned int, unix_skb_len(skb) - skip, size);
2029                 if (skb_copy_datagram_msg(skb, UNIXCB(skb).consumed + skip,
2030                                           msg, chunk)) {
2031                         if (copied == 0)
2032                                 copied = -EFAULT;
2033                         break;
2034                 }
2035                 copied += chunk;
2036                 size -= chunk;
2037 
2038                 /* Mark read part of skb as used */
2039                 if (!(flags & MSG_PEEK)) {
2040                         UNIXCB(skb).consumed += chunk;
2041 
2042                         sk_peek_offset_bwd(sk, chunk);
2043 
2044                         if (UNIXCB(skb).fp)
2045                                 unix_detach_fds(&scm, skb);
2046 
2047                         if (unix_skb_len(skb))
2048                                 break;
2049 
2050                         skb_unlink(skb, &sk->sk_receive_queue);
2051                         consume_skb(skb);
2052 
2053                         if (scm.fp)
2054                                 break;
2055                 } else {
2056                         /* It is questionable, see note in unix_dgram_recvmsg.
2057                          */
2058                         if (UNIXCB(skb).fp)
2059                                 scm.fp = scm_fp_dup(UNIXCB(skb).fp);
2060 
2061                         sk_peek_offset_fwd(sk, chunk);
2062 
2063                         break;
2064                 }
2065         } while (size);
2066 
2067         mutex_unlock(&u->readlock);
2068         scm_recv(sock, msg, &scm, flags);
2069 out:
2070         return copied ? : err;
2071 }
2072 
2073 static int unix_shutdown(struct socket *sock, int mode)
2074 {
2075         struct sock *sk = sock->sk;
2076         struct sock *other;
2077 
2078         if (mode < SHUT_RD || mode > SHUT_RDWR)
2079                 return -EINVAL;
2080         /* This maps:
2081          * SHUT_RD   (0) -> RCV_SHUTDOWN  (1)
2082          * SHUT_WR   (1) -> SEND_SHUTDOWN (2)
2083          * SHUT_RDWR (2) -> SHUTDOWN_MASK (3)
2084          */
2085         ++mode;
2086 
2087         unix_state_lock(sk);
2088         sk->sk_shutdown |= mode;
2089         other = unix_peer(sk);
2090         if (other)
2091                 sock_hold(other);
2092         unix_state_unlock(sk);
2093         sk->sk_state_change(sk);
2094 
2095         if (other &&
2096                 (sk->sk_type == SOCK_STREAM || sk->sk_type == SOCK_SEQPACKET)) {
2097 
2098                 int peer_mode = 0;
2099 
2100                 if (mode&RCV_SHUTDOWN)
2101                         peer_mode |= SEND_SHUTDOWN;
2102                 if (mode&SEND_SHUTDOWN)
2103                         peer_mode |= RCV_SHUTDOWN;
2104                 unix_state_lock(other);
2105                 other->sk_shutdown |= peer_mode;
2106                 unix_state_unlock(other);
2107                 other->sk_state_change(other);
2108                 if (peer_mode == SHUTDOWN_MASK)
2109                         sk_wake_async(other, SOCK_WAKE_WAITD, POLL_HUP);
2110                 else if (peer_mode & RCV_SHUTDOWN)
2111                         sk_wake_async(other, SOCK_WAKE_WAITD, POLL_IN);
2112         }
2113         if (other)
2114                 sock_put(other);
2115 
2116         return 0;
2117 }
2118 
2119 long unix_inq_len(struct sock *sk)
2120 {
2121         struct sk_buff *skb;
2122         long amount = 0;
2123 
2124         if (sk->sk_state == TCP_LISTEN)
2125                 return -EINVAL;
2126 
2127         spin_lock(&sk->sk_receive_queue.lock);
2128         if (sk->sk_type == SOCK_STREAM ||
2129             sk->sk_type == SOCK_SEQPACKET) {
2130                 skb_queue_walk(&sk->sk_receive_queue, skb)
2131                         amount += unix_skb_len(skb);
2132         } else {
2133                 skb = skb_peek(&sk->sk_receive_queue);
2134                 if (skb)
2135                         amount = skb->len;
2136         }
2137         spin_unlock(&sk->sk_receive_queue.lock);
2138 
2139         return amount;
2140 }
2141 EXPORT_SYMBOL_GPL(unix_inq_len);
2142 
2143 long unix_outq_len(struct sock *sk)
2144 {
2145         return sk_wmem_alloc_get(sk);
2146 }
2147 EXPORT_SYMBOL_GPL(unix_outq_len);
2148 
2149 static int unix_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
2150 {
2151         struct sock *sk = sock->sk;
2152         long amount = 0;
2153         int err;
2154 
2155         switch (cmd) {
2156         case SIOCOUTQ:
2157                 amount = unix_outq_len(sk);
2158                 err = put_user(amount, (int __user *)arg);
2159                 break;
2160         case SIOCINQ:
2161                 amount = unix_inq_len(sk);
2162                 if (amount < 0)
2163                         err = amount;
2164                 else
2165                         err = put_user(amount, (int __user *)arg);
2166                 break;
2167         default:
2168                 err = -ENOIOCTLCMD;
2169                 break;
2170         }
2171         return err;
2172 }
2173 
2174 static unsigned int unix_poll(struct file *file, struct socket *sock, poll_table *wait)
2175 {
2176         struct sock *sk = sock->sk;
2177         unsigned int mask;
2178 
2179         sock_poll_wait(file, sk_sleep(sk), wait);
2180         mask = 0;
2181 
2182         /* exceptional events? */
2183         if (sk->sk_err)
2184                 mask |= POLLERR;
2185         if (sk->sk_shutdown == SHUTDOWN_MASK)
2186                 mask |= POLLHUP;
2187         if (sk->sk_shutdown & RCV_SHUTDOWN)
2188                 mask |= POLLRDHUP | POLLIN | POLLRDNORM;
2189 
2190         /* readable? */
2191         if (!skb_queue_empty(&sk->sk_receive_queue))
2192                 mask |= POLLIN | POLLRDNORM;
2193 
2194         /* Connection-based need to check for termination and startup */
2195         if ((sk->sk_type == SOCK_STREAM || sk->sk_type == SOCK_SEQPACKET) &&
2196             sk->sk_state == TCP_CLOSE)
2197                 mask |= POLLHUP;
2198 
2199         /*
2200          * we set writable also when the other side has shut down the
2201          * connection. This prevents stuck sockets.
2202          */
2203         if (unix_writable(sk))
2204                 mask |= POLLOUT | POLLWRNORM | POLLWRBAND;
2205 
2206         return mask;
2207 }
2208 
2209 static unsigned int unix_dgram_poll(struct file *file, struct socket *sock,
2210                                     poll_table *wait)
2211 {
2212         struct sock *sk = sock->sk, *other;
2213         unsigned int mask, writable;
2214 
2215         sock_poll_wait(file, sk_sleep(sk), wait);
2216         mask = 0;
2217 
2218         /* exceptional events? */
2219         if (sk->sk_err || !skb_queue_empty(&sk->sk_error_queue))
2220                 mask |= POLLERR |
2221                         (sock_flag(sk, SOCK_SELECT_ERR_QUEUE) ? POLLPRI : 0);
2222 
2223         if (sk->sk_shutdown & RCV_SHUTDOWN)
2224                 mask |= POLLRDHUP | POLLIN | POLLRDNORM;
2225         if (sk->sk_shutdown == SHUTDOWN_MASK)
2226                 mask |= POLLHUP;
2227 
2228         /* readable? */
2229         if (!skb_queue_empty(&sk->sk_receive_queue))
2230                 mask |= POLLIN | POLLRDNORM;
2231 
2232         /* Connection-based need to check for termination and startup */
2233         if (sk->sk_type == SOCK_SEQPACKET) {
2234                 if (sk->sk_state == TCP_CLOSE)
2235                         mask |= POLLHUP;
2236                 /* connection hasn't started yet? */
2237                 if (sk->sk_state == TCP_SYN_SENT)
2238                         return mask;
2239         }
2240 
2241         /* No write status requested, avoid expensive OUT tests. */
2242         if (!(poll_requested_events(wait) & (POLLWRBAND|POLLWRNORM|POLLOUT)))
2243                 return mask;
2244 
2245         writable = unix_writable(sk);
2246         other = unix_peer_get(sk);
2247         if (other) {
2248                 if (unix_peer(other) != sk) {
2249                         sock_poll_wait(file, &unix_sk(other)->peer_wait, wait);
2250                         if (unix_recvq_full(other))
2251                                 writable = 0;
2252                 }
2253                 sock_put(other);
2254         }
2255 
2256         if (writable)
2257                 mask |= POLLOUT | POLLWRNORM | POLLWRBAND;
2258         else
2259                 set_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
2260 
2261         return mask;
2262 }
2263 
2264 #ifdef CONFIG_PROC_FS
2265 
2266 #define BUCKET_SPACE (BITS_PER_LONG - (UNIX_HASH_BITS + 1) - 1)
2267 
2268 #define get_bucket(x) ((x) >> BUCKET_SPACE)
2269 #define get_offset(x) ((x) & ((1L << BUCKET_SPACE) - 1))
2270 #define set_bucket_offset(b, o) ((b) << BUCKET_SPACE | (o))
2271 
2272 static struct sock *unix_from_bucket(struct seq_file *seq, loff_t *pos)
2273 {
2274         unsigned long offset = get_offset(*pos);
2275         unsigned long bucket = get_bucket(*pos);
2276         struct sock *sk;
2277         unsigned long count = 0;
2278 
2279         for (sk = sk_head(&unix_socket_table[bucket]); sk; sk = sk_next(sk)) {
2280                 if (sock_net(sk) != seq_file_net(seq))
2281                         continue;
2282                 if (++count == offset)
2283                         break;
2284         }
2285 
2286         return sk;
2287 }
2288 
2289 static struct sock *unix_next_socket(struct seq_file *seq,
2290                                      struct sock *sk,
2291                                      loff_t *pos)
2292 {
2293         unsigned long bucket;
2294 
2295         while (sk > (struct sock *)SEQ_START_TOKEN) {
2296                 sk = sk_next(sk);
2297                 if (!sk)
2298                         goto next_bucket;
2299                 if (sock_net(sk) == seq_file_net(seq))
2300                         return sk;
2301         }
2302 
2303         do {
2304                 sk = unix_from_bucket(seq, pos);
2305                 if (sk)
2306                         return sk;
2307 
2308 next_bucket:
2309                 bucket = get_bucket(*pos) + 1;
2310                 *pos = set_bucket_offset(bucket, 1);
2311         } while (bucket < ARRAY_SIZE(unix_socket_table));
2312 
2313         return NULL;
2314 }
2315 
2316 static void *unix_seq_start(struct seq_file *seq, loff_t *pos)
2317         __acquires(unix_table_lock)
2318 {
2319         spin_lock(&unix_table_lock);
2320 
2321         if (!*pos)
2322                 return SEQ_START_TOKEN;
2323 
2324         if (get_bucket(*pos) >= ARRAY_SIZE(unix_socket_table))
2325                 return NULL;
2326 
2327         return unix_next_socket(seq, NULL, pos);
2328 }
2329 
2330 static void *unix_seq_next(struct seq_file *seq, void *v, loff_t *pos)
2331 {
2332         ++*pos;
2333         return unix_next_socket(seq, v, pos);
2334 }
2335 
2336 static void unix_seq_stop(struct seq_file *seq, void *v)
2337         __releases(unix_table_lock)
2338 {
2339         spin_unlock(&unix_table_lock);
2340 }
2341 
2342 static int unix_seq_show(struct seq_file *seq, void *v)
2343 {
2344 
2345         if (v == SEQ_START_TOKEN)
2346                 seq_puts(seq, "Num       RefCount Protocol Flags    Type St "
2347                          "Inode Path\n");
2348         else {
2349                 struct sock *s = v;
2350                 struct unix_sock *u = unix_sk(s);
2351                 unix_state_lock(s);
2352 
2353                 seq_printf(seq, "%pK: %08X %08X %08X %04X %02X %5lu",
2354                         s,
2355                         atomic_read(&s->sk_refcnt),
2356                         0,
2357                         s->sk_state == TCP_LISTEN ? __SO_ACCEPTCON : 0,
2358                         s->sk_type,
2359                         s->sk_socket ?
2360                         (s->sk_state == TCP_ESTABLISHED ? SS_CONNECTED : SS_UNCONNECTED) :
2361                         (s->sk_state == TCP_ESTABLISHED ? SS_CONNECTING : SS_DISCONNECTING),
2362                         sock_i_ino(s));
2363 
2364                 if (u->addr) {
2365                         int i, len;
2366                         seq_putc(seq, ' ');
2367 
2368                         i = 0;
2369                         len = u->addr->len - sizeof(short);
2370                         if (!UNIX_ABSTRACT(s))
2371                                 len--;
2372                         else {
2373                                 seq_putc(seq, '@');
2374                                 i++;
2375                         }
2376                         for ( ; i < len; i++)
2377                                 seq_putc(seq, u->addr->name->sun_path[i]);
2378                 }
2379                 unix_state_unlock(s);
2380                 seq_putc(seq, '\n');
2381         }
2382 
2383         return 0;
2384 }
2385 
2386 static const struct seq_operations unix_seq_ops = {
2387         .start  = unix_seq_start,
2388         .next   = unix_seq_next,
2389         .stop   = unix_seq_stop,
2390         .show   = unix_seq_show,
2391 };
2392 
2393 static int unix_seq_open(struct inode *inode, struct file *file)
2394 {
2395         return seq_open_net(inode, file, &unix_seq_ops,
2396                             sizeof(struct seq_net_private));
2397 }
2398 
2399 static const struct file_operations unix_seq_fops = {
2400         .owner          = THIS_MODULE,
2401         .open           = unix_seq_open,
2402         .read           = seq_read,
2403         .llseek         = seq_lseek,
2404         .release        = seq_release_net,
2405 };
2406 
2407 #endif
2408 
2409 static const struct net_proto_family unix_family_ops = {
2410         .family = PF_UNIX,
2411         .create = unix_create,
2412         .owner  = THIS_MODULE,
2413 };
2414 
2415 
2416 static int __net_init unix_net_init(struct net *net)
2417 {
2418         int error = -ENOMEM;
2419 
2420         net->unx.sysctl_max_dgram_qlen = 10;
2421         if (unix_sysctl_register(net))
2422                 goto out;
2423 
2424 #ifdef CONFIG_PROC_FS
2425         if (!proc_create("unix", 0, net->proc_net, &unix_seq_fops)) {
2426                 unix_sysctl_unregister(net);
2427                 goto out;
2428         }
2429 #endif
2430         error = 0;
2431 out:
2432         return error;
2433 }
2434 
2435 static void __net_exit unix_net_exit(struct net *net)
2436 {
2437         unix_sysctl_unregister(net);
2438         remove_proc_entry("unix", net->proc_net);
2439 }
2440 
2441 static struct pernet_operations unix_net_ops = {
2442         .init = unix_net_init,
2443         .exit = unix_net_exit,
2444 };
2445 
2446 static int __init af_unix_init(void)
2447 {
2448         int rc = -1;
2449 
2450         BUILD_BUG_ON(sizeof(struct unix_skb_parms) > FIELD_SIZEOF(struct sk_buff, cb));
2451 
2452         rc = proto_register(&unix_proto, 1);
2453         if (rc != 0) {
2454                 pr_crit("%s: Cannot create unix_sock SLAB cache!\n", __func__);
2455                 goto out;
2456         }
2457 
2458         sock_register(&unix_family_ops);
2459         register_pernet_subsys(&unix_net_ops);
2460 out:
2461         return rc;
2462 }
2463 
2464 static void __exit af_unix_exit(void)
2465 {
2466         sock_unregister(PF_UNIX);
2467         proto_unregister(&unix_proto);
2468         unregister_pernet_subsys(&unix_net_ops);
2469 }
2470 
2471 /* Earlier than device_initcall() so that other drivers invoking
2472    request_module() don't end up in a loop when modprobe tries
2473    to use a UNIX socket. But later than subsys_initcall() because
2474    we depend on stuff initialised there */
2475 fs_initcall(af_unix_init);
2476 module_exit(af_unix_exit);
2477 
2478 MODULE_LICENSE("GPL");
2479 MODULE_ALIAS_NETPROTO(PF_UNIX);
2480 

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