Linux/net/unix/af_unix.c

  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 #include <linux/module.h>
 84 #include <linux/kernel.h>
 85 #include <linux/signal.h>
 86 #include <linux/sched.h>
 87 #include <linux/errno.h>
 88 #include <linux/string.h>
 89 #include <linux/stat.h>
 90 #include <linux/dcache.h>
 91 #include <linux/namei.h>
 92 #include <linux/socket.h>
 93 #include <linux/un.h>
 94 #include <linux/fcntl.h>
 95 #include <linux/termios.h>
 96 #include <linux/sockios.h>
 97 #include <linux/net.h>
 98 #include <linux/in.h>
 99 #include <linux/fs.h>
100 #include <linux/slab.h>
101 #include <asm/uaccess.h>
102 #include <linux/skbuff.h>
103 #include <linux/netdevice.h>
104 #include <net/net_namespace.h>
105 #include <net/sock.h>
106 #include <net/tcp_states.h>
107 #include <net/af_unix.h>
108 #include <linux/proc_fs.h>
109 #include <linux/seq_file.h>
110 #include <net/scm.h>
111 #include <linux/init.h>
112 #include <linux/poll.h>
113 #include <linux/rtnetlink.h>
114 #include <linux/mount.h>
115 #include <net/checksum.h>
116 #include <linux/security.h>
117 
118 static struct hlist_head unix_socket_table[UNIX_HASH_SIZE + 1];
119 static DEFINE_SPINLOCK(unix_table_lock);
120 static atomic_long_t unix_nr_socks;
121 
122 #define unix_sockets_unbound    (&unix_socket_table[UNIX_HASH_SIZE])
123 
124 #define UNIX_ABSTRACT(sk)       (unix_sk(sk)->addr->hash != UNIX_HASH_SIZE)
125 
126 #ifdef CONFIG_SECURITY_NETWORK
127 static void unix_get_secdata(struct scm_cookie *scm, struct sk_buff *skb)
128 {
129         memcpy(UNIXSID(skb), &scm->secid, sizeof(u32));
130 }
131 
132 static inline void unix_set_secdata(struct scm_cookie *scm, struct sk_buff *skb)
133 {
134         scm->secid = *UNIXSID(skb);
135 }
136 #else
137 static inline void unix_get_secdata(struct scm_cookie *scm, struct sk_buff *skb)
138 { }
139 
140 static inline void unix_set_secdata(struct scm_cookie *scm, struct sk_buff *skb)
141 { }
142 #endif /* CONFIG_SECURITY_NETWORK */
143 
144 /*
145  *  SMP locking strategy:
146  *    hash table is protected with spinlock unix_table_lock
147  *    each socket state is protected by separate spin lock.
148  */
149 
150 static inline unsigned unix_hash_fold(__wsum n)
151 {
152         unsigned hash = (__force unsigned)n;
153         hash ^= hash>>16;
154         hash ^= hash>>8;
155         return hash&(UNIX_HASH_SIZE-1);
156 }
157 
158 #define unix_peer(sk) (unix_sk(sk)->peer)
159 
160 static inline int unix_our_peer(struct sock *sk, struct sock *osk)
161 {
162         return unix_peer(osk) == sk;
163 }
164 
165 static inline int unix_may_send(struct sock *sk, struct sock *osk)
166 {
167         return unix_peer(osk) == NULL || unix_our_peer(sk, osk);
168 }
169 
170 static inline int unix_recvq_full(struct sock const *sk)
171 {
172         return skb_queue_len(&sk->sk_receive_queue) > sk->sk_max_ack_backlog;
173 }
174 
175 static struct sock *unix_peer_get(struct sock *s)
176 {
177         struct sock *peer;
178 
179         unix_state_lock(s);
180         peer = unix_peer(s);
181         if (peer)
182                 sock_hold(peer);
183         unix_state_unlock(s);
184         return peer;
185 }
186 
187 static inline void unix_release_addr(struct unix_address *addr)
188 {
189         if (atomic_dec_and_test(&addr->refcnt))
190                 kfree(addr);
191 }
192 
193 /*
194  *      Check unix socket name:
195  *              - should be not zero length.
196  *              - if started by not zero, should be NULL terminated (FS object)
197  *              - if started by zero, it is abstract name.
198  */
199 
200 static int unix_mkname(struct sockaddr_un *sunaddr, int len, unsigned *hashp)
201 {
202         if (len <= sizeof(short) || len > sizeof(*sunaddr))
203                 return -EINVAL;
204         if (!sunaddr || sunaddr->sun_family != AF_UNIX)
205                 return -EINVAL;
206         if (sunaddr->sun_path[0]) {
207                 /*
208                  * This may look like an off by one error but it is a bit more
209                  * subtle. 108 is the longest valid AF_UNIX path for a binding.
210                  * sun_path[108] doesnt as such exist.  However in kernel space
211                  * we are guaranteed that it is a valid memory location in our
212                  * kernel address buffer.
213                  */
214                 ((char *)sunaddr)[len] = 0;
215                 len = strlen(sunaddr->sun_path)+1+sizeof(short);
216                 return len;
217         }
218 
219         *hashp = unix_hash_fold(csum_partial(sunaddr, len, 0));
220         return len;
221 }
222 
223 static void __unix_remove_socket(struct sock *sk)
224 {
225         sk_del_node_init(sk);
226 }
227 
228 static void __unix_insert_socket(struct hlist_head *list, struct sock *sk)
229 {
230         WARN_ON(!sk_unhashed(sk));
231         sk_add_node(sk, list);
232 }
233 
234 static inline void unix_remove_socket(struct sock *sk)
235 {
236         spin_lock(&unix_table_lock);
237         __unix_remove_socket(sk);
238         spin_unlock(&unix_table_lock);
239 }
240 
241 static inline void unix_insert_socket(struct hlist_head *list, struct sock *sk)
242 {
243         spin_lock(&unix_table_lock);
244         __unix_insert_socket(list, sk);
245         spin_unlock(&unix_table_lock);
246 }
247 
248 static struct sock *__unix_find_socket_byname(struct net *net,
249                                               struct sockaddr_un *sunname,
250                                               int len, int type, unsigned hash)
251 {
252         struct sock *s;
253         struct hlist_node *node;
254 
255         sk_for_each(s, node, &unix_socket_table[hash ^ type]) {
256                 struct unix_sock *u = unix_sk(s);
257 
258                 if (!net_eq(sock_net(s), net))
259                         continue;
260 
261                 if (u->addr->len == len &&
262                     !memcmp(u->addr->name, sunname, len))
263                         goto found;
264         }
265         s = NULL;
266 found:
267         return s;
268 }
269 
270 static inline struct sock *unix_find_socket_byname(struct net *net,
271                                                    struct sockaddr_un *sunname,
272                                                    int len, int type,
273                                                    unsigned hash)
274 {
275         struct sock *s;
276 
277         spin_lock(&unix_table_lock);
278         s = __unix_find_socket_byname(net, sunname, len, type, hash);
279         if (s)
280                 sock_hold(s);
281         spin_unlock(&unix_table_lock);
282         return s;
283 }
284 
285 static struct sock *unix_find_socket_byinode(struct inode *i)
286 {
287         struct sock *s;
288         struct hlist_node *node;
289 
290         spin_lock(&unix_table_lock);
291         sk_for_each(s, node,
292                     &unix_socket_table[i->i_ino & (UNIX_HASH_SIZE - 1)]) {
293                 struct dentry *dentry = unix_sk(s)->dentry;
294 
295                 if (dentry && dentry->d_inode == i) {
296                         sock_hold(s);
297                         goto found;
298                 }
299         }
300         s = NULL;
301 found:
302         spin_unlock(&unix_table_lock);
303         return s;
304 }
305 
306 static inline int unix_writable(struct sock *sk)
307 {
308         return (atomic_read(&sk->sk_wmem_alloc) << 2) <= sk->sk_sndbuf;
309 }
310 
311 static void unix_write_space(struct sock *sk)
312 {
313         struct socket_wq *wq;
314 
315         rcu_read_lock();
316         if (unix_writable(sk)) {
317                 wq = rcu_dereference(sk->sk_wq);
318                 if (wq_has_sleeper(wq))
319                         wake_up_interruptible_sync(&wq->wait);
320                 sk_wake_async(sk, SOCK_WAKE_SPACE, POLL_OUT);
321         }
322         rcu_read_unlock();
323 }
324 
325 /* When dgram socket disconnects (or changes its peer), we clear its receive
326  * queue of packets arrived from previous peer. First, it allows to do
327  * flow control based only on wmem_alloc; second, sk connected to peer
328  * may receive messages only from that peer. */
329 static void unix_dgram_disconnected(struct sock *sk, struct sock *other)
330 {
331         if (!skb_queue_empty(&sk->sk_receive_queue)) {
332                 skb_queue_purge(&sk->sk_receive_queue);
333                 wake_up_interruptible_all(&unix_sk(sk)->peer_wait);
334 
335                 /* If one link of bidirectional dgram pipe is disconnected,
336                  * we signal error. Messages are lost. Do not make this,
337                  * when peer was not connected to us.
338                  */
339                 if (!sock_flag(other, SOCK_DEAD) && unix_peer(other) == sk) {
340                         other->sk_err = ECONNRESET;
341                         other->sk_error_report(other);
342                 }
343         }
344 }
345 
346 static void unix_sock_destructor(struct sock *sk)
347 {
348         struct unix_sock *u = unix_sk(sk);
349 
350         skb_queue_purge(&sk->sk_receive_queue);
351 
352         WARN_ON(atomic_read(&sk->sk_wmem_alloc));
353         WARN_ON(!sk_unhashed(sk));
354         WARN_ON(sk->sk_socket);
355         if (!sock_flag(sk, SOCK_DEAD)) {
356                 printk(KERN_INFO "Attempt to release alive unix socket: %p\n", sk);
357                 return;
358         }
359 
360         if (u->addr)
361                 unix_release_addr(u->addr);
362 
363         atomic_long_dec(&unix_nr_socks);
364         local_bh_disable();
365         sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
366         local_bh_enable();
367 #ifdef UNIX_REFCNT_DEBUG
368         printk(KERN_DEBUG "UNIX %p is destroyed, %ld are still alive.\n", sk,
369                 atomic_long_read(&unix_nr_socks));
370 #endif
371 }
372 
373 static int unix_release_sock(struct sock *sk, int embrion)
374 {
375         struct unix_sock *u = unix_sk(sk);
376         struct dentry *dentry;
377         struct vfsmount *mnt;
378         struct sock *skpair;
379         struct sk_buff *skb;
380         int state;
381 
382         unix_remove_socket(sk);
383 
384         /* Clear state */
385         unix_state_lock(sk);
386         sock_orphan(sk);
387         sk->sk_shutdown = SHUTDOWN_MASK;
388         dentry       = u->dentry;
389         u->dentry    = NULL;
390         mnt          = u->mnt;
391         u->mnt       = NULL;
392         state = sk->sk_state;
393         sk->sk_state = TCP_CLOSE;
394         unix_state_unlock(sk);
395 
396         wake_up_interruptible_all(&u->peer_wait);
397 
398         skpair = unix_peer(sk);
399 
400         if (skpair != NULL) {
401                 if (sk->sk_type == SOCK_STREAM || sk->sk_type == SOCK_SEQPACKET) {
402                         unix_state_lock(skpair);
403                         /* No more writes */
404                         skpair->sk_shutdown = SHUTDOWN_MASK;
405                         if (!skb_queue_empty(&sk->sk_receive_queue) || embrion)
406                                 skpair->sk_err = ECONNRESET;
407                         unix_state_unlock(skpair);
408                         skpair->sk_state_change(skpair);
409                         sk_wake_async(skpair, SOCK_WAKE_WAITD, POLL_HUP);
410                 }
411                 sock_put(skpair); /* It may now die */
412                 unix_peer(sk) = NULL;
413         }
414 
415         /* Try to flush out this socket. Throw out buffers at least */
416 
417         while ((skb = skb_dequeue(&sk->sk_receive_queue)) != NULL) {
418                 if (state == TCP_LISTEN)
419                         unix_release_sock(skb->sk, 1);
420                 /* passed fds are erased in the kfree_skb hook        */
421                 kfree_skb(skb);
422         }
423 
424         if (dentry) {
425                 dput(dentry);
426                 mntput(mnt);
427         }
428 
429         sock_put(sk);
430 
431         /* ---- Socket is dead now and most probably destroyed ---- */
432 
433         /*
434          * Fixme: BSD difference: In BSD all sockets connected to use get
435          *        ECONNRESET and we die on the spot. In Linux we behave
436          *        like files and pipes do and wait for the last
437          *        dereference.
438          *
439          * Can't we simply set sock->err?
440          *
441          *        What the above comment does talk about? --ANK(980817)
442          */
443 
444         if (unix_tot_inflight)
445                 unix_gc();              /* Garbage collect fds */
446 
447         return 0;
448 }
449 
450 static void init_peercred(struct sock *sk)
451 {
452         put_pid(sk->sk_peer_pid);
453         if (sk->sk_peer_cred)
454                 put_cred(sk->sk_peer_cred);
455         sk->sk_peer_pid  = get_pid(task_tgid(current));
456         sk->sk_peer_cred = get_current_cred();
457 }
458 
459 static void copy_peercred(struct sock *sk, struct sock *peersk)
460 {
461         put_pid(sk->sk_peer_pid);
462         if (sk->sk_peer_cred)
463                 put_cred(sk->sk_peer_cred);
464         sk->sk_peer_pid  = get_pid(peersk->sk_peer_pid);
465         sk->sk_peer_cred = get_cred(peersk->sk_peer_cred);
466 }
467 
468 static int unix_listen(struct socket *sock, int backlog)
469 {
470         int err;
471         struct sock *sk = sock->sk;
472         struct unix_sock *u = unix_sk(sk);
473         struct pid *old_pid = NULL;
474         const struct cred *old_cred = NULL;
475 
476         err = -EOPNOTSUPP;
477         if (sock->type != SOCK_STREAM && sock->type != SOCK_SEQPACKET)
478                 goto out;       /* Only stream/seqpacket sockets accept */
479         err = -EINVAL;
480         if (!u->addr)
481                 goto out;       /* No listens on an unbound socket */
482         unix_state_lock(sk);
483         if (sk->sk_state != TCP_CLOSE && sk->sk_state != TCP_LISTEN)
484                 goto out_unlock;
485         if (backlog > sk->sk_max_ack_backlog)
486                 wake_up_interruptible_all(&u->peer_wait);
487         sk->sk_max_ack_backlog  = backlog;
488         sk->sk_state            = TCP_LISTEN;
489         /* set credentials so connect can copy them */
490         init_peercred(sk);
491         err = 0;
492 
493 out_unlock:
494         unix_state_unlock(sk);
495         put_pid(old_pid);
496         if (old_cred)
497                 put_cred(old_cred);
498 out:
499         return err;
500 }
501 
502 static int unix_release(struct socket *);
503 static int unix_bind(struct socket *, struct sockaddr *, int);
504 static int unix_stream_connect(struct socket *, struct sockaddr *,
505                                int addr_len, int flags);
506 static int unix_socketpair(struct socket *, struct socket *);
507 static int unix_accept(struct socket *, struct socket *, int);
508 static int unix_getname(struct socket *, struct sockaddr *, int *, int);
509 static unsigned int unix_poll(struct file *, struct socket *, poll_table *);
510 static unsigned int unix_dgram_poll(struct file *, struct socket *,
511                                     poll_table *);
512 static int unix_ioctl(struct socket *, unsigned int, unsigned long);
513 static int unix_shutdown(struct socket *, int);
514 static int unix_stream_sendmsg(struct kiocb *, struct socket *,
515                                struct msghdr *, size_t);
516 static int unix_stream_recvmsg(struct kiocb *, struct socket *,
517                                struct msghdr *, size_t, int);
518 static int unix_dgram_sendmsg(struct kiocb *, struct socket *,
519                               struct msghdr *, size_t);
520 static int unix_dgram_recvmsg(struct kiocb *, struct socket *,
521                               struct msghdr *, size_t, int);
522 static int unix_dgram_connect(struct socket *, struct sockaddr *,
523                               int, int);
524 static int unix_seqpacket_sendmsg(struct kiocb *, struct socket *,
525                                   struct msghdr *, size_t);
526 
527 static const struct proto_ops unix_stream_ops = {
528         .family =       PF_UNIX,
529         .owner =        THIS_MODULE,
530         .release =      unix_release,
531         .bind =         unix_bind,
532         .connect =      unix_stream_connect,
533         .socketpair =   unix_socketpair,
534         .accept =       unix_accept,
535         .getname =      unix_getname,
536         .poll =         unix_poll,
537         .ioctl =        unix_ioctl,
538         .listen =       unix_listen,
539         .shutdown =     unix_shutdown,
540         .setsockopt =   sock_no_setsockopt,
541         .getsockopt =   sock_no_getsockopt,
542         .sendmsg =      unix_stream_sendmsg,
543         .recvmsg =      unix_stream_recvmsg,
544         .mmap =         sock_no_mmap,
545         .sendpage =     sock_no_sendpage,
546 };
547 
548 static const struct proto_ops unix_dgram_ops = {
549         .family =       PF_UNIX,
550         .owner =        THIS_MODULE,
551         .release =      unix_release,
552         .bind =         unix_bind,
553         .connect =      unix_dgram_connect,
554         .socketpair =   unix_socketpair,
555         .accept =       sock_no_accept,
556         .getname =      unix_getname,
557         .poll =         unix_dgram_poll,
558         .ioctl =        unix_ioctl,
559         .listen =       sock_no_listen,
560         .shutdown =     unix_shutdown,
561         .setsockopt =   sock_no_setsockopt,
562         .getsockopt =   sock_no_getsockopt,
563         .sendmsg =      unix_dgram_sendmsg,
564         .recvmsg =      unix_dgram_recvmsg,
565         .mmap =         sock_no_mmap,
566         .sendpage =     sock_no_sendpage,
567 };
568 
569 static const struct proto_ops unix_seqpacket_ops = {
570         .family =       PF_UNIX,
571         .owner =        THIS_MODULE,
572         .release =      unix_release,
573         .bind =         unix_bind,
574         .connect =      unix_stream_connect,
575         .socketpair =   unix_socketpair,
576         .accept =       unix_accept,
577         .getname =      unix_getname,
578         .poll =         unix_dgram_poll,
579         .ioctl =        unix_ioctl,
580         .listen =       unix_listen,
581         .shutdown =     unix_shutdown,
582         .setsockopt =   sock_no_setsockopt,
583         .getsockopt =   sock_no_getsockopt,
584         .sendmsg =      unix_seqpacket_sendmsg,
585         .recvmsg =      unix_dgram_recvmsg,
586         .mmap =         sock_no_mmap,
587         .sendpage =     sock_no_sendpage,
588 };
589 
590 static struct proto unix_proto = {
591         .name                   = "UNIX",
592         .owner                  = THIS_MODULE,
593         .obj_size               = sizeof(struct unix_sock),
594 };
595 
596 /*
597  * AF_UNIX sockets do not interact with hardware, hence they
598  * dont trigger interrupts - so it's safe for them to have
599  * bh-unsafe locking for their sk_receive_queue.lock. Split off
600  * this special lock-class by reinitializing the spinlock key:
601  */
602 static struct lock_class_key af_unix_sk_receive_queue_lock_key;
603 
604 static struct sock *unix_create1(struct net *net, struct socket *sock)
605 {
606         struct sock *sk = NULL;
607         struct unix_sock *u;
608 
609         atomic_long_inc(&unix_nr_socks);
610         if (atomic_long_read(&unix_nr_socks) > 2 * get_max_files())
611                 goto out;
612 
613         sk = sk_alloc(net, PF_UNIX, GFP_KERNEL, &unix_proto);
614         if (!sk)
615                 goto out;
616 
617         sock_init_data(sock, sk);
618         lockdep_set_class(&sk->sk_receive_queue.lock,
619                                 &af_unix_sk_receive_queue_lock_key);
620 
621         sk->sk_write_space      = unix_write_space;
622         sk->sk_max_ack_backlog  = net->unx.sysctl_max_dgram_qlen;
623         sk->sk_destruct         = unix_sock_destructor;
624         u         = unix_sk(sk);
625         u->dentry = NULL;
626         u->mnt    = NULL;
627         spin_lock_init(&u->lock);
628         atomic_long_set(&u->inflight, 0);
629         INIT_LIST_HEAD(&u->link);
630         mutex_init(&u->readlock); /* single task reading lock */
631         init_waitqueue_head(&u->peer_wait);
632         unix_insert_socket(unix_sockets_unbound, sk);
633 out:
634         if (sk == NULL)
635                 atomic_long_dec(&unix_nr_socks);
636         else {
637                 local_bh_disable();
638                 sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
639                 local_bh_enable();
640         }
641         return sk;
642 }
643 
644 static int unix_create(struct net *net, struct socket *sock, int protocol,
645                        int kern)
646 {
647         if (protocol && protocol != PF_UNIX)
648                 return -EPROTONOSUPPORT;
649 
650         sock->state = SS_UNCONNECTED;
651 
652         switch (sock->type) {
653         case SOCK_STREAM:
654                 sock->ops = &unix_stream_ops;
655                 break;
656                 /*
657                  *      Believe it or not BSD has AF_UNIX, SOCK_RAW though
658                  *      nothing uses it.
659                  */
660         case SOCK_RAW:
661                 sock->type = SOCK_DGRAM;
662         case SOCK_DGRAM:
663                 sock->ops = &unix_dgram_ops;
664                 break;
665         case SOCK_SEQPACKET:
666                 sock->ops = &unix_seqpacket_ops;
667                 break;
668         default:
669                 return -ESOCKTNOSUPPORT;
670         }
671 
672         return unix_create1(net, sock) ? 0 : -ENOMEM;
673 }
674 
675 static int unix_release(struct socket *sock)
676 {
677         struct sock *sk = sock->sk;
678 
679         if (!sk)
680                 return 0;
681 
682         sock->sk = NULL;
683 
684         return unix_release_sock(sk, 0);
685 }
686 
687 static int unix_autobind(struct socket *sock)
688 {
689         struct sock *sk = sock->sk;
690         struct net *net = sock_net(sk);
691         struct unix_sock *u = unix_sk(sk);
692         static u32 ordernum = 1;
693         struct unix_address *addr;
694         int err;
695         unsigned int retries = 0;
696 
697         mutex_lock(&u->readlock);
698 
699         err = 0;
700         if (u->addr)
701                 goto out;
702 
703         err = -ENOMEM;
704         addr = kzalloc(sizeof(*addr) + sizeof(short) + 16, GFP_KERNEL);
705         if (!addr)
706                 goto out;
707 
708         addr->name->sun_family = AF_UNIX;
709         atomic_set(&addr->refcnt, 1);
710 
711 retry:
712         addr->len = sprintf(addr->name->sun_path+1, "%05x", ordernum) + 1 + sizeof(short);
713         addr->hash = unix_hash_fold(csum_partial(addr->name, addr->len, 0));
714 
715         spin_lock(&unix_table_lock);
716         ordernum = (ordernum+1)&0xFFFFF;
717 
718         if (__unix_find_socket_byname(net, addr->name, addr->len, sock->type,
719                                       addr->hash)) {
720                 spin_unlock(&unix_table_lock);
721                 /*
722                  * __unix_find_socket_byname() may take long time if many names
723                  * are already in use.
724                  */
725                 cond_resched();
726                 /* Give up if all names seems to be in use. */
727                 if (retries++ == 0xFFFFF) {
728                         err = -ENOSPC;
729                         kfree(addr);
730                         goto out;
731                 }
732                 goto retry;
733         }
734         addr->hash ^= sk->sk_type;
735 
736         __unix_remove_socket(sk);
737         u->addr = addr;
738         __unix_insert_socket(&unix_socket_table[addr->hash], sk);
739         spin_unlock(&unix_table_lock);
740         err = 0;
741 
742 out:    mutex_unlock(&u->readlock);
743         return err;
744 }
745 
746 static struct sock *unix_find_other(struct net *net,
747                                     struct sockaddr_un *sunname, int len,
748                                     int type, unsigned hash, int *error)
749 {
750         struct sock *u;
751         struct path path;
752         int err = 0;
753 
754         if (sunname->sun_path[0]) {
755                 struct inode *inode;
756                 err = kern_path(sunname->sun_path, LOOKUP_FOLLOW, &path);
757                 if (err)
758                         goto fail;
759                 inode = path.dentry->d_inode;
760                 err = inode_permission(inode, MAY_WRITE);
761                 if (err)
762                         goto put_fail;
763 
764                 err = -ECONNREFUSED;
765                 if (!S_ISSOCK(inode->i_mode))
766                         goto put_fail;
767                 u = unix_find_socket_byinode(inode);
768                 if (!u)
769                         goto put_fail;
770 
771                 if (u->sk_type == type)
772                         touch_atime(path.mnt, path.dentry);
773 
774                 path_put(&path);
775 
776                 err = -EPROTOTYPE;
777                 if (u->sk_type != type) {
778                         sock_put(u);
779                         goto fail;
780                 }
781         } else {
782                 err = -ECONNREFUSED;
783                 u = unix_find_socket_byname(net, sunname, len, type, hash);
784                 if (u) {
785                         struct dentry *dentry;
786                         dentry = unix_sk(u)->dentry;
787                         if (dentry)
788                                 touch_atime(unix_sk(u)->mnt, dentry);
789                 } else
790                         goto fail;
791         }
792         return u;
793 
794 put_fail:
795         path_put(&path);
796 fail:
797         *error = err;
798         return NULL;
799 }
800 
801 
802 static int unix_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
803 {
804         struct sock *sk = sock->sk;
805         struct net *net = sock_net(sk);
806         struct unix_sock *u = unix_sk(sk);
807         struct sockaddr_un *sunaddr = (struct sockaddr_un *)uaddr;
808         struct dentry *dentry = NULL;
809         struct nameidata nd;
810         int err;
811         unsigned hash;
812         struct unix_address *addr;
813         struct hlist_head *list;
814 
815         err = -EINVAL;
816         if (sunaddr->sun_family != AF_UNIX)
817                 goto out;
818 
819         if (addr_len == sizeof(short)) {
820                 err = unix_autobind(sock);
821                 goto out;
822         }
823 
824         err = unix_mkname(sunaddr, addr_len, &hash);
825         if (err < 0)
826                 goto out;
827         addr_len = err;
828 
829         mutex_lock(&u->readlock);
830 
831         err = -EINVAL;
832         if (u->addr)
833                 goto out_up;
834 
835         err = -ENOMEM;
836         addr = kmalloc(sizeof(*addr)+addr_len, GFP_KERNEL);
837         if (!addr)
838                 goto out_up;
839 
840         memcpy(addr->name, sunaddr, addr_len);
841         addr->len = addr_len;
842         addr->hash = hash ^ sk->sk_type;
843         atomic_set(&addr->refcnt, 1);
844 
845         if (sunaddr->sun_path[0]) {
846                 unsigned int mode;
847                 err = 0;
848                 /*
849                  * Get the parent directory, calculate the hash for last
850                  * component.
851                  */
852                 err = path_lookup(sunaddr->sun_path, LOOKUP_PARENT, &nd);
853                 if (err)
854                         goto out_mknod_parent;
855 
856                 dentry = lookup_create(&nd, 0);
857                 err = PTR_ERR(dentry);
858                 if (IS_ERR(dentry))
859                         goto out_mknod_unlock;
860 
861                 /*
862                  * All right, let's create it.
863                  */
864                 mode = S_IFSOCK |
865                        (SOCK_INODE(sock)->i_mode & ~current_umask());
866                 err = mnt_want_write(nd.path.mnt);
867                 if (err)
868                         goto out_mknod_dput;
869                 err = security_path_mknod(&nd.path, dentry, mode, 0);
870                 if (err)
871                         goto out_mknod_drop_write;
872                 err = vfs_mknod(nd.path.dentry->d_inode, dentry, mode, 0);
873 out_mknod_drop_write:
874                 mnt_drop_write(nd.path.mnt);
875                 if (err)
876                         goto out_mknod_dput;
877                 mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
878                 dput(nd.path.dentry);
879                 nd.path.dentry = dentry;
880 
881                 addr->hash = UNIX_HASH_SIZE;
882         }
883 
884         spin_lock(&unix_table_lock);
885 
886         if (!sunaddr->sun_path[0]) {
887                 err = -EADDRINUSE;
888                 if (__unix_find_socket_byname(net, sunaddr, addr_len,
889                                               sk->sk_type, hash)) {
890                         unix_release_addr(addr);
891                         goto out_unlock;
892                 }
893 
894                 list = &unix_socket_table[addr->hash];
895         } else {
896                 list = &unix_socket_table[dentry->d_inode->i_ino & (UNIX_HASH_SIZE-1)];
897                 u->dentry = nd.path.dentry;
898                 u->mnt    = nd.path.mnt;
899         }
900 
901         err = 0;
902         __unix_remove_socket(sk);
903         u->addr = addr;
904         __unix_insert_socket(list, sk);
905 
906 out_unlock:
907         spin_unlock(&unix_table_lock);
908 out_up:
909         mutex_unlock(&u->readlock);
910 out:
911         return err;
912 
913 out_mknod_dput:
914         dput(dentry);
915 out_mknod_unlock:
916         mutex_unlock(&nd.path.dentry->d_inode->i_mutex);
917         path_put(&nd.path);
918 out_mknod_parent:
919         if (err == -EEXIST)
920                 err = -EADDRINUSE;
921         unix_release_addr(addr);
922         goto out_up;
923 }
924 
925 static void unix_state_double_lock(struct sock *sk1, struct sock *sk2)
926 {
927         if (unlikely(sk1 == sk2) || !sk2) {
928                 unix_state_lock(sk1);
929                 return;
930         }
931         if (sk1 < sk2) {
932                 unix_state_lock(sk1);
933                 unix_state_lock_nested(sk2);
934         } else {
935                 unix_state_lock(sk2);
936                 unix_state_lock_nested(sk1);
937         }
938 }
939 
940 static void unix_state_double_unlock(struct sock *sk1, struct sock *sk2)
941 {
942         if (unlikely(sk1 == sk2) || !sk2) {
943                 unix_state_unlock(sk1);
944                 return;
945         }
946         unix_state_unlock(sk1);
947         unix_state_unlock(sk2);
948 }
949 
950 static int unix_dgram_connect(struct socket *sock, struct sockaddr *addr,
951                               int alen, int flags)
952 {
953         struct sock *sk = sock->sk;
954         struct net *net = sock_net(sk);
955         struct sockaddr_un *sunaddr = (struct sockaddr_un *)addr;
956         struct sock *other;
957         unsigned hash;
958         int err;
959 
960         if (addr->sa_family != AF_UNSPEC) {
961                 err = unix_mkname(sunaddr, alen, &hash);
962                 if (err < 0)
963                         goto out;
964                 alen = err;
965 
966                 if (test_bit(SOCK_PASSCRED, &sock->flags) &&
967                     !unix_sk(sk)->addr && (err = unix_autobind(sock)) != 0)
968                         goto out;
969 
970 restart:
971                 other = unix_find_other(net, sunaddr, alen, sock->type, hash, &err);
972                 if (!other)
973                         goto out;
974 
975                 unix_state_double_lock(sk, other);
976 
977                 /* Apparently VFS overslept socket death. Retry. */
978                 if (sock_flag(other, SOCK_DEAD)) {
979                         unix_state_double_unlock(sk, other);
980                         sock_put(other);
981                         goto restart;
982                 }
983 
984                 err = -EPERM;
985                 if (!unix_may_send(sk, other))
986                         goto out_unlock;
987 
988                 err = security_unix_may_send(sk->sk_socket, other->sk_socket);
989                 if (err)
990                         goto out_unlock;
991 
992         } else {
993                 /*
994                  *      1003.1g breaking connected state with AF_UNSPEC
995                  */
996                 other = NULL;
997                 unix_state_double_lock(sk, other);
998         }
999 
1000         /*
1001          * If it was connected, reconnect.
1002          */
1003         if (unix_peer(sk)) {
1004                 struct sock *old_peer = unix_peer(sk);
1005                 unix_peer(sk) = other;
1006                 unix_state_double_unlock(sk, other);
1007 
1008                 if (other != old_peer)
1009                         unix_dgram_disconnected(sk, old_peer);
1010                 sock_put(old_peer);
1011         } else {
1012                 unix_peer(sk) = other;
1013                 unix_state_double_unlock(sk, other);
1014         }
1015         return 0;
1016 
1017 out_unlock:
1018         unix_state_double_unlock(sk, other);
1019         sock_put(other);
1020 out:
1021         return err;
1022 }
1023 
1024 static long unix_wait_for_peer(struct sock *other, long timeo)
1025 {
1026         struct unix_sock *u = unix_sk(other);
1027         int sched;
1028         DEFINE_WAIT(wait);
1029 
1030         prepare_to_wait_exclusive(&u->peer_wait, &wait, TASK_INTERRUPTIBLE);
1031 
1032         sched = !sock_flag(other, SOCK_DEAD) &&
1033                 !(other->sk_shutdown & RCV_SHUTDOWN) &&
1034                 unix_recvq_full(other);
1035 
1036         unix_state_unlock(other);
1037 
1038         if (sched)
1039                 timeo = schedule_timeout(timeo);
1040 
1041         finish_wait(&u->peer_wait, &wait);
1042         return timeo;
1043 }
1044 
1045 static int unix_stream_connect(struct socket *sock, struct sockaddr *uaddr,
1046                                int addr_len, int flags)
1047 {
1048         struct sockaddr_un *sunaddr = (struct sockaddr_un *)uaddr;
1049         struct sock *sk = sock->sk;
1050         struct net *net = sock_net(sk);
1051         struct unix_sock *u = unix_sk(sk), *newu, *otheru;
1052         struct sock *newsk = NULL;
1053         struct sock *other = NULL;
1054         struct sk_buff *skb = NULL;
1055         unsigned hash;
1056         int st;
1057         int err;
1058         long timeo;
1059 
1060         err = unix_mkname(sunaddr, addr_len, &hash);
1061         if (err < 0)
1062                 goto out;
1063         addr_len = err;
1064 
1065         if (test_bit(SOCK_PASSCRED, &sock->flags) && !u->addr &&
1066             (err = unix_autobind(sock)) != 0)
1067                 goto out;
1068 
1069         timeo = sock_sndtimeo(sk, flags & O_NONBLOCK);
1070 
1071         /* First of all allocate resources.
1072            If we will make it after state is locked,
1073            we will have to recheck all again in any case.
1074          */
1075 
1076         err = -ENOMEM;
1077 
1078         /* create new sock for complete connection */
1079         newsk = unix_create1(sock_net(sk), NULL);
1080         if (newsk == NULL)
1081                 goto out;
1082 
1083         /* Allocate skb for sending to listening sock */
1084         skb = sock_wmalloc(newsk, 1, 0, GFP_KERNEL);
1085         if (skb == NULL)
1086                 goto out;
1087 
1088 restart:
1089         /*  Find listening sock. */
1090         other = unix_find_other(net, sunaddr, addr_len, sk->sk_type, hash, &err);
1091         if (!other)
1092                 goto out;
1093 
1094         /* Latch state of peer */
1095         unix_state_lock(other);
1096 
1097         /* Apparently VFS overslept socket death. Retry. */
1098         if (sock_flag(other, SOCK_DEAD)) {
1099                 unix_state_unlock(other);
1100                 sock_put(other);
1101                 goto restart;
1102         }
1103 
1104         err = -ECONNREFUSED;
1105         if (other->sk_state != TCP_LISTEN)
1106                 goto out_unlock;
1107         if (other->sk_shutdown & RCV_SHUTDOWN)
1108                 goto out_unlock;
1109 
1110         if (unix_recvq_full(other)) {
1111                 err = -EAGAIN;
1112                 if (!timeo)
1113                         goto out_unlock;
1114 
1115                 timeo = unix_wait_for_peer(other, timeo);
1116 
1117                 err = sock_intr_errno(timeo);
1118                 if (signal_pending(current))
1119                         goto out;
1120                 sock_put(other);
1121                 goto restart;
1122         }
1123 
1124         /* Latch our state.
1125 
1126            It is tricky place. We need to grab write lock and cannot
1127            drop lock on peer. It is dangerous because deadlock is
1128            possible. Connect to self case and simultaneous
1129            attempt to connect are eliminated by checking socket
1130            state. other is TCP_LISTEN, if sk is TCP_LISTEN we
1131            check this before attempt to grab lock.
1132 
1133            Well, and we have to recheck the state after socket locked.
1134          */
1135         st = sk->sk_state;
1136 
1137         switch (st) {
1138         case TCP_CLOSE:
1139                 /* This is ok... continue with connect */
1140                 break;
1141         case TCP_ESTABLISHED:
1142                 /* Socket is already connected */
1143                 err = -EISCONN;
1144                 goto out_unlock;
1145         default:
1146                 err = -EINVAL;
1147                 goto out_unlock;
1148         }
1149 
1150         unix_state_lock_nested(sk);
1151 
1152         if (sk->sk_state != st) {
1153                 unix_state_unlock(sk);
1154                 unix_state_unlock(other);
1155                 sock_put(other);
1156                 goto restart;
1157         }
1158 
1159         err = security_unix_stream_connect(sock, other->sk_socket, newsk);
1160         if (err) {
1161                 unix_state_unlock(sk);
1162                 goto out_unlock;
1163         }
1164 
1165         /* The way is open! Fastly set all the necessary fields... */
1166 
1167         sock_hold(sk);
1168         unix_peer(newsk)        = sk;
1169         newsk->sk_state         = TCP_ESTABLISHED;
1170         newsk->sk_type          = sk->sk_type;
1171         init_peercred(newsk);
1172         newu = unix_sk(newsk);
1173         newsk->sk_wq            = &newu->peer_wq;
1174         otheru = unix_sk(other);
1175 
1176         /* copy address information from listening to new sock*/
1177         if (otheru->addr) {
1178                 atomic_inc(&otheru->addr->refcnt);
1179                 newu->addr = otheru->addr;
1180         }
1181         if (otheru->dentry) {
1182                 newu->dentry    = dget(otheru->dentry);
1183                 newu->mnt       = mntget(otheru->mnt);
1184         }
1185 
1186         /* Set credentials */
1187         copy_peercred(sk, other);
1188 
1189         sock->state     = SS_CONNECTED;
1190         sk->sk_state    = TCP_ESTABLISHED;
1191         sock_hold(newsk);
1192 
1193         smp_mb__after_atomic_inc();     /* sock_hold() does an atomic_inc() */
1194         unix_peer(sk)   = newsk;
1195 
1196         unix_state_unlock(sk);
1197 
1198         /* take ten and and send info to listening sock */
1199         spin_lock(&other->sk_receive_queue.lock);
1200         __skb_queue_tail(&other->sk_receive_queue, skb);
1201         spin_unlock(&other->sk_receive_queue.lock);
1202         unix_state_unlock(other);
1203         other->sk_data_ready(other, 0);
1204         sock_put(other);
1205         return 0;
1206 
1207 out_unlock:
1208         if (other)
1209                 unix_state_unlock(other);
1210 
1211 out:
1212         kfree_skb(skb);
1213         if (newsk)
1214                 unix_release_sock(newsk, 0);
1215         if (other)
1216                 sock_put(other);
1217         return err;
1218 }
1219 
1220 static int unix_socketpair(struct socket *socka, struct socket *sockb)
1221 {
1222         struct sock *ska = socka->sk, *skb = sockb->sk;
1223 
1224         /* Join our sockets back to back */
1225         sock_hold(ska);
1226         sock_hold(skb);
1227         unix_peer(ska) = skb;
1228         unix_peer(skb) = ska;
1229         init_peercred(ska);
1230         init_peercred(skb);
1231 
1232         if (ska->sk_type != SOCK_DGRAM) {
1233                 ska->sk_state = TCP_ESTABLISHED;
1234                 skb->sk_state = TCP_ESTABLISHED;
1235                 socka->state  = SS_CONNECTED;
1236                 sockb->state  = SS_CONNECTED;
1237         }
1238         return 0;
1239 }
1240 
1241 static int unix_accept(struct socket *sock, struct socket *newsock, int flags)
1242 {
1243         struct sock *sk = sock->sk;
1244         struct sock *tsk;
1245         struct sk_buff *skb;
1246         int err;
1247 
1248         err = -EOPNOTSUPP;
1249         if (sock->type != SOCK_STREAM && sock->type != SOCK_SEQPACKET)
1250                 goto out;
1251 
1252         err = -EINVAL;
1253         if (sk->sk_state != TCP_LISTEN)
1254                 goto out;
1255 
1256         /* If socket state is TCP_LISTEN it cannot change (for now...),
1257          * so that no locks are necessary.
1258          */
1259 
1260         skb = skb_recv_datagram(sk, 0, flags&O_NONBLOCK, &err);
1261         if (!skb) {
1262                 /* This means receive shutdown. */
1263                 if (err == 0)
1264                         err = -EINVAL;
1265                 goto out;
1266         }
1267 
1268         tsk = skb->sk;
1269         skb_free_datagram(sk, skb);
1270         wake_up_interruptible(&unix_sk(sk)->peer_wait);
1271 
1272         /* attach accepted sock to socket */
1273         unix_state_lock(tsk);
1274         newsock->state = SS_CONNECTED;
1275         sock_graft(tsk, newsock);
1276         unix_state_unlock(tsk);
1277         return 0;
1278 
1279 out:
1280         return err;
1281 }
1282 
1283 
1284 static int unix_getname(struct socket *sock, struct sockaddr *uaddr, int *uaddr_len, int peer)
1285 {
1286         struct sock *sk = sock->sk;
1287         struct unix_sock *u;
1288         DECLARE_SOCKADDR(struct sockaddr_un *, sunaddr, uaddr);
1289         int err = 0;
1290 
1291         if (peer) {
1292                 sk = unix_peer_get(sk);
1293 
1294                 err = -ENOTCONN;
1295                 if (!sk)
1296                         goto out;
1297                 err = 0;
1298         } else {
1299                 sock_hold(sk);
1300         }
1301 
1302         u = unix_sk(sk);
1303         unix_state_lock(sk);
1304         if (!u->addr) {
1305                 sunaddr->sun_family = AF_UNIX;
1306                 sunaddr->sun_path[0] = 0;
1307                 *uaddr_len = sizeof(short);
1308         } else {
1309                 struct unix_address *addr = u->addr;
1310 
1311                 *uaddr_len = addr->len;
1312                 memcpy(sunaddr, addr->name, *uaddr_len);
1313         }
1314         unix_state_unlock(sk);
1315         sock_put(sk);
1316 out:
1317         return err;
1318 }
1319 
1320 static void unix_detach_fds(struct scm_cookie *scm, struct sk_buff *skb)
1321 {
1322         int i;
1323 
1324         scm->fp = UNIXCB(skb).fp;
1325         UNIXCB(skb).fp = NULL;
1326 
1327         for (i = scm->fp->count-1; i >= 0; i--)
1328                 unix_notinflight(scm->fp->fp[i]);
1329 }
1330 
1331 static void unix_destruct_scm(struct sk_buff *skb)
1332 {
1333         struct scm_cookie scm;
1334         memset(&scm, 0, sizeof(scm));
1335         scm.pid  = UNIXCB(skb).pid;
1336         scm.cred = UNIXCB(skb).cred;
1337         if (UNIXCB(skb).fp)
1338                 unix_detach_fds(&scm, skb);
1339 
1340         /* Alas, it calls VFS */
1341         /* So fscking what? fput() had been SMP-safe since the last Summer */
1342         scm_destroy(&scm);
1343         sock_wfree(skb);
1344 }
1345 
1346 #define MAX_RECURSION_LEVEL 4
1347 
1348 static int unix_attach_fds(struct scm_cookie *scm, struct sk_buff *skb)
1349 {
1350         int i;
1351         unsigned char max_level = 0;
1352         int unix_sock_count = 0;
1353 
1354         for (i = scm->fp->count - 1; i >= 0; i--) {
1355                 struct sock *sk = unix_get_socket(scm->fp->fp[i]);
1356 
1357                 if (sk) {
1358                         unix_sock_count++;
1359                         max_level = max(max_level,
1360                                         unix_sk(sk)->recursion_level);
1361                 }
1362         }
1363         if (unlikely(max_level > MAX_RECURSION_LEVEL))
1364                 return -ETOOMANYREFS;
1365 
1366         /*
1367          * Need to duplicate file references for the sake of garbage
1368          * collection.  Otherwise a socket in the fps might become a
1369          * candidate for GC while the skb is not yet queued.
1370          */
1371         UNIXCB(skb).fp = scm_fp_dup(scm->fp);
1372         if (!UNIXCB(skb).fp)
1373                 return -ENOMEM;
1374 
1375         if (unix_sock_count) {
1376                 for (i = scm->fp->count - 1; i >= 0; i--)
1377                         unix_inflight(scm->fp->fp[i]);
1378         }
1379         return max_level;
1380 }
1381 
1382 static int unix_scm_to_skb(struct scm_cookie *scm, struct sk_buff *skb, bool send_fds)
1383 {
1384         int err = 0;
1385         UNIXCB(skb).pid  = get_pid(scm->pid);
1386         UNIXCB(skb).cred = get_cred(scm->cred);
1387         UNIXCB(skb).fp = NULL;
1388         if (scm->fp && send_fds)
1389                 err = unix_attach_fds(scm, skb);
1390 
1391         skb->destructor = unix_destruct_scm;
1392         return err;
1393 }
1394 
1395 /*
1396  *      Send AF_UNIX data.
1397  */
1398 
1399 static int unix_dgram_sendmsg(struct kiocb *kiocb, struct socket *sock,
1400                               struct msghdr *msg, size_t len)
1401 {
1402         struct sock_iocb *siocb = kiocb_to_siocb(kiocb);
1403         struct sock *sk = sock->sk;
1404         struct net *net = sock_net(sk);
1405         struct unix_sock *u = unix_sk(sk);
1406         struct sockaddr_un *sunaddr = msg->msg_name;
1407         struct sock *other = NULL;
1408         int namelen = 0; /* fake GCC */
1409         int err;
1410         unsigned hash;
1411         struct sk_buff *skb;
1412         long timeo;
1413         struct scm_cookie tmp_scm;
1414         int max_level;
1415 
1416         if (NULL == siocb->scm)
1417                 siocb->scm = &tmp_scm;
1418         wait_for_unix_gc();
1419         err = scm_send(sock, msg, siocb->scm);
1420         if (err < 0)
1421                 return err;
1422 
1423         err = -EOPNOTSUPP;
1424         if (msg->msg_flags&MSG_OOB)
1425                 goto out;
1426 
1427         if (msg->msg_namelen) {
1428                 err = unix_mkname(sunaddr, msg->msg_namelen, &hash);
1429                 if (err < 0)
1430                         goto out;
1431                 namelen = err;
1432         } else {
1433                 sunaddr = NULL;
1434                 err = -ENOTCONN;
1435                 other = unix_peer_get(sk);
1436                 if (!other)
1437                         goto out;
1438         }
1439 
1440         if (test_bit(SOCK_PASSCRED, &sock->flags) && !u->addr
1441             && (err = unix_autobind(sock)) != 0)
1442                 goto out;
1443 
1444         err = -EMSGSIZE;
1445         if (len > sk->sk_sndbuf - 32)
1446                 goto out;
1447 
1448         skb = sock_alloc_send_skb(sk, len, msg->msg_flags&MSG_DONTWAIT, &err);
1449         if (skb == NULL)
1450                 goto out;
1451 
1452         err = unix_scm_to_skb(siocb->scm, skb, true);
1453         if (err < 0)
1454                 goto out_free;
1455         max_level = err + 1;
1456         unix_get_secdata(siocb->scm, skb);
1457 
1458         skb_reset_transport_header(skb);
1459         err = memcpy_fromiovec(skb_put(skb, len), msg->msg_iov, len);
1460         if (err)
1461                 goto out_free;
1462 
1463         timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT);
1464 
1465 restart:
1466         if (!other) {
1467                 err = -ECONNRESET;
1468                 if (sunaddr == NULL)
1469                         goto out_free;
1470 
1471                 other = unix_find_other(net, sunaddr, namelen, sk->sk_type,
1472                                         hash, &err);
1473                 if (other == NULL)
1474                         goto out_free;
1475         }
1476 
1477         unix_state_lock(other);
1478         err = -EPERM;
1479         if (!unix_may_send(sk, other))
1480                 goto out_unlock;
1481 
1482         if (sock_flag(other, SOCK_DEAD)) {
1483                 /*
1484                  *      Check with 1003.1g - what should
1485                  *      datagram error
1486                  */
1487                 unix_state_unlock(other);
1488                 sock_put(other);
1489 
1490                 err = 0;
1491                 unix_state_lock(sk);
1492                 if (unix_peer(sk) == other) {
1493                         unix_peer(sk) = NULL;
1494                         unix_state_unlock(sk);
1495 
1496                         unix_dgram_disconnected(sk, other);
1497                         sock_put(other);
1498                         err = -ECONNREFUSED;
1499                 } else {
1500                         unix_state_unlock(sk);
1501                 }
1502 
1503                 other = NULL;
1504                 if (err)
1505                         goto out_free;
1506                 goto restart;
1507         }
1508 
1509         err = -EPIPE;
1510         if (other->sk_shutdown & RCV_SHUTDOWN)
1511                 goto out_unlock;
1512 
1513         if (sk->sk_type != SOCK_SEQPACKET) {
1514                 err = security_unix_may_send(sk->sk_socket, other->sk_socket);
1515                 if (err)
1516                         goto out_unlock;
1517         }
1518 
1519         if (unix_peer(other) != sk && unix_recvq_full(other)) {
1520                 if (!timeo) {
1521                         err = -EAGAIN;
1522                         goto out_unlock;
1523                 }
1524 
1525                 timeo = unix_wait_for_peer(other, timeo);
1526 
1527                 err = sock_intr_errno(timeo);
1528                 if (signal_pending(current))
1529                         goto out_free;
1530 
1531                 goto restart;
1532         }
1533 
1534         if (sock_flag(other, SOCK_RCVTSTAMP))
1535                 __net_timestamp(skb);
1536         skb_queue_tail(&other->sk_receive_queue, skb);
1537         if (max_level > unix_sk(other)->recursion_level)
1538                 unix_sk(other)->recursion_level = max_level;
1539         unix_state_unlock(other);
1540         other->sk_data_ready(other, len);
1541         sock_put(other);
1542         scm_destroy(siocb->scm);
1543         return len;
1544 
1545 out_unlock:
1546         unix_state_unlock(other);
1547 out_free:
1548         kfree_skb(skb);
1549 out:
1550         if (other)
1551                 sock_put(other);
1552         scm_destroy(siocb->scm);
1553         return err;
1554 }
1555 
1556 
1557 static int unix_stream_sendmsg(struct kiocb *kiocb, struct socket *sock,
1558                                struct msghdr *msg, size_t len)
1559 {
1560         struct sock_iocb *siocb = kiocb_to_siocb(kiocb);
1561         struct sock *sk = sock->sk;
1562         struct sock *other = NULL;
1563         struct sockaddr_un *sunaddr = msg->msg_name;
1564         int err, size;
1565         struct sk_buff *skb;
1566         int sent = 0;
1567         struct scm_cookie tmp_scm;
1568         bool fds_sent = false;
1569         int max_level;
1570 
1571         if (NULL == siocb->scm)
1572                 siocb->scm = &tmp_scm;
1573         wait_for_unix_gc();
1574         err = scm_send(sock, msg, siocb->scm);
1575         if (err < 0)
1576                 return err;
1577 
1578         err = -EOPNOTSUPP;
1579         if (msg->msg_flags&MSG_OOB)
1580                 goto out_err;
1581 
1582         if (msg->msg_namelen) {
1583                 err = sk->sk_state == TCP_ESTABLISHED ? -EISCONN : -EOPNOTSUPP;
1584                 goto out_err;
1585         } else {
1586                 sunaddr = NULL;
1587                 err = -ENOTCONN;
1588                 other = unix_peer(sk);
1589                 if (!other)
1590                         goto out_err;
1591         }
1592 
1593         if (sk->sk_shutdown & SEND_SHUTDOWN)
1594                 goto pipe_err;
1595 
1596         while (sent < len) {
1597                 /*
1598                  *      Optimisation for the fact that under 0.01% of X
1599                  *      messages typically need breaking up.
1600                  */
1601 
1602                 size = len-sent;
1603 
1604                 /* Keep two messages in the pipe so it schedules better */
1605                 if (size > ((sk->sk_sndbuf >> 1) - 64))
1606                         size = (sk->sk_sndbuf >> 1) - 64;
1607 
1608                 if (size > SKB_MAX_ALLOC)
1609                         size = SKB_MAX_ALLOC;
1610 
1611                 /*
1612                  *      Grab a buffer
1613                  */
1614 
1615                 skb = sock_alloc_send_skb(sk, size, msg->msg_flags&MSG_DONTWAIT,
1616                                           &err);
1617 
1618                 if (skb == NULL)
1619                         goto out_err;
1620 
1621                 /*
1622                  *      If you pass two values to the sock_alloc_send_skb
1623                  *      it tries to grab the large buffer with GFP_NOFS
1624                  *      (which can fail easily), and if it fails grab the
1625                  *      fallback size buffer which is under a page and will
1626                  *      succeed. [Alan]
1627                  */
1628                 size = min_t(int, size, skb_tailroom(skb));
1629 
1630 
1631                 /* Only send the fds in the first buffer */
1632                 err = unix_scm_to_skb(siocb->scm, skb, !fds_sent);
1633                 if (err < 0) {
1634                         kfree_skb(skb);
1635                         goto out_err;
1636                 }
1637                 max_level = err + 1;
1638                 fds_sent = true;
1639 
1640                 err = memcpy_fromiovec(skb_put(skb, size), msg->msg_iov, size);
1641                 if (err) {
1642                         kfree_skb(skb);
1643                         goto out_err;
1644                 }
1645 
1646                 unix_state_lock(other);
1647 
1648                 if (sock_flag(other, SOCK_DEAD) ||
1649                     (other->sk_shutdown & RCV_SHUTDOWN))
1650                         goto pipe_err_free;
1651 
1652                 skb_queue_tail(&other->sk_receive_queue, skb);
1653                 if (max_level > unix_sk(other)->recursion_level)
1654                         unix_sk(other)->recursion_level = max_level;
1655                 unix_state_unlock(other);
1656                 other->sk_data_ready(other, size);
1657                 sent += size;
1658         }
1659 
1660         scm_destroy(siocb->scm);
1661         siocb->scm = NULL;
1662 
1663         return sent;
1664 
1665 pipe_err_free:
1666         unix_state_unlock(other);
1667         kfree_skb(skb);
1668 pipe_err:
1669         if (sent == 0 && !(msg->msg_flags&MSG_NOSIGNAL))
1670                 send_sig(SIGPIPE, current, 0);
1671         err = -EPIPE;
1672 out_err:
1673         scm_destroy(siocb->scm);
1674         siocb->scm = NULL;
1675         return sent ? : err;
1676 }
1677 
1678 static int unix_seqpacket_sendmsg(struct kiocb *kiocb, struct socket *sock,
1679                                   struct msghdr *msg, size_t len)
1680 {
1681         int err;
1682         struct sock *sk = sock->sk;
1683 
1684         err = sock_error(sk);
1685         if (err)
1686                 return err;
1687 
1688         if (sk->sk_state != TCP_ESTABLISHED)
1689                 return -ENOTCONN;
1690 
1691         if (msg->msg_namelen)
1692                 msg->msg_namelen = 0;
1693 
1694         return unix_dgram_sendmsg(kiocb, sock, msg, len);
1695 }
1696 
1697 static void unix_copy_addr(struct msghdr *msg, struct sock *sk)
1698 {
1699         struct unix_sock *u = unix_sk(sk);
1700 
1701         msg->msg_namelen = 0;
1702         if (u->addr) {
1703                 msg->msg_namelen = u->addr->len;
1704                 memcpy(msg->msg_name, u->addr->name, u->addr->len);
1705         }
1706 }
1707 
1708 static int unix_dgram_recvmsg(struct kiocb *iocb, struct socket *sock,
1709                               struct msghdr *msg, size_t size,
1710                               int flags)
1711 {
1712         struct sock_iocb *siocb = kiocb_to_siocb(iocb);
1713         struct scm_cookie tmp_scm;
1714         struct sock *sk = sock->sk;
1715         struct unix_sock *u = unix_sk(sk);
1716         int noblock = flags & MSG_DONTWAIT;
1717         struct sk_buff *skb;
1718         int err;
1719 
1720         err = -EOPNOTSUPP;
1721         if (flags&MSG_OOB)
1722                 goto out;
1723 
1724         msg->msg_namelen = 0;
1725 
1726         mutex_lock(&u->readlock);
1727 
1728         skb = skb_recv_datagram(sk, flags, noblock, &err);
1729         if (!skb) {
1730                 unix_state_lock(sk);
1731                 /* Signal EOF on disconnected non-blocking SEQPACKET socket. */
1732                 if (sk->sk_type == SOCK_SEQPACKET && err == -EAGAIN &&
1733                     (sk->sk_shutdown & RCV_SHUTDOWN))
1734                         err = 0;
1735                 unix_state_unlock(sk);
1736                 goto out_unlock;
1737         }
1738 
1739         wake_up_interruptible_sync(&u->peer_wait);
1740 
1741         if (msg->msg_name)
1742                 unix_copy_addr(msg, skb->sk);
1743 
1744         if (size > skb->len)
1745                 size = skb->len;
1746         else if (size < skb->len)
1747                 msg->msg_flags |= MSG_TRUNC;
1748 
1749         err = skb_copy_datagram_iovec(skb, 0, msg->msg_iov, size);
1750         if (err)
1751                 goto out_free;
1752 
1753         if (sock_flag(sk, SOCK_RCVTSTAMP))
1754                 __sock_recv_timestamp(msg, sk, skb);
1755 
1756         if (!siocb->scm) {
1757                 siocb->scm = &tmp_scm;
1758                 memset(&tmp_scm, 0, sizeof(tmp_scm));
1759         }
1760         scm_set_cred(siocb->scm, UNIXCB(skb).pid, UNIXCB(skb).cred);
1761         unix_set_secdata(siocb->scm, skb);
1762 
1763         if (!(flags & MSG_PEEK)) {
1764                 if (UNIXCB(skb).fp)
1765                         unix_detach_fds(siocb->scm, skb);
1766         } else {
1767                 /* It is questionable: on PEEK we could:
1768                    - do not return fds - good, but too simple 8)
1769                    - return fds, and do not return them on read (old strategy,
1770                      apparently wrong)
1771                    - clone fds (I chose it for now, it is the most universal
1772                      solution)
1773 
1774                    POSIX 1003.1g does not actually define this clearly
1775                    at all. POSIX 1003.1g doesn't define a lot of things
1776                    clearly however!
1777 
1778                 */
1779                 if (UNIXCB(skb).fp)
1780                         siocb->scm->fp = scm_fp_dup(UNIXCB(skb).fp);
1781         }
1782         err = size;
1783 
1784         scm_recv(sock, msg, siocb->scm, flags);
1785 
1786 out_free:
1787         skb_free_datagram(sk, skb);
1788 out_unlock:
1789         mutex_unlock(&u->readlock);
1790 out:
1791         return err;
1792 }
1793 
1794 /*
1795  *      Sleep until data has arrive. But check for races..
1796  */
1797 
1798 static long unix_stream_data_wait(struct sock *sk, long timeo)
1799 {
1800         DEFINE_WAIT(wait);
1801 
1802         unix_state_lock(sk);
1803 
1804         for (;;) {
1805                 prepare_to_wait(sk_sleep(sk), &wait, TASK_INTERRUPTIBLE);
1806 
1807                 if (!skb_queue_empty(&sk->sk_receive_queue) ||
1808                     sk->sk_err ||
1809                     (sk->sk_shutdown & RCV_SHUTDOWN) ||
1810                     signal_pending(current) ||
1811                     !timeo)
1812                         break;
1813 
1814                 set_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags);
1815                 unix_state_unlock(sk);
1816                 timeo = schedule_timeout(timeo);
1817                 unix_state_lock(sk);
1818                 clear_bit(SOCK_ASYNC_WAITDATA, &sk->sk_socket->flags);
1819         }
1820 
1821         finish_wait(sk_sleep(sk), &wait);
1822         unix_state_unlock(sk);
1823         return timeo;
1824 }
1825 
1826 
1827 
1828 static int unix_stream_recvmsg(struct kiocb *iocb, struct socket *sock,
1829                                struct msghdr *msg, size_t size,
1830                                int flags)
1831 {
1832         struct sock_iocb *siocb = kiocb_to_siocb(iocb);
1833         struct scm_cookie tmp_scm;
1834         struct sock *sk = sock->sk;
1835         struct unix_sock *u = unix_sk(sk);
1836         struct sockaddr_un *sunaddr = msg->msg_name;
1837         int copied = 0;
1838         int check_creds = 0;
1839         int target;
1840         int err = 0;
1841         long timeo;
1842 
1843         err = -EINVAL;
1844         if (sk->sk_state != TCP_ESTABLISHED)
1845                 goto out;
1846 
1847         err = -EOPNOTSUPP;
1848         if (flags&MSG_OOB)
1849                 goto out;
1850 
1851         target = sock_rcvlowat(sk, flags&MSG_WAITALL, size);
1852         timeo = sock_rcvtimeo(sk, flags&MSG_DONTWAIT);
1853 
1854         msg->msg_namelen = 0;
1855 
1856         /* Lock the socket to prevent queue disordering
1857          * while sleeps in memcpy_tomsg
1858          */
1859 
1860         if (!siocb->scm) {
1861                 siocb->scm = &tmp_scm;
1862                 memset(&tmp_scm, 0, sizeof(tmp_scm));
1863         }
1864 
1865         mutex_lock(&u->readlock);
1866 
1867         do {
1868                 int chunk;
1869                 struct sk_buff *skb;
1870 
1871                 unix_state_lock(sk);
1872                 skb = skb_dequeue(&sk->sk_receive_queue);
1873                 if (skb == NULL) {
1874                         unix_sk(sk)->recursion_level = 0;
1875                         if (copied >= target)
1876                                 goto unlock;
1877 
1878                         /*
1879                          *      POSIX 1003.1g mandates this order.
1880                          */
1881 
1882                         err = sock_error(sk);
1883                         if (err)
1884                                 goto unlock;
1885                         if (sk->sk_shutdown & RCV_SHUTDOWN)
1886                                 goto unlock;
1887 
1888                         unix_state_unlock(sk);
1889                         err = -EAGAIN;
1890                         if (!timeo)
1891                                 break;
1892                         mutex_unlock(&u->readlock);
1893 
1894                         timeo = unix_stream_data_wait(sk, timeo);
1895 
1896                         if (signal_pending(current)) {
1897                                 err = sock_intr_errno(timeo);
1898                                 goto out;
1899                         }
1900                         mutex_lock(&u->readlock);
1901                         continue;
1902  unlock:
1903                         unix_state_unlock(sk);
1904                         break;
1905                 }
1906                 unix_state_unlock(sk);
1907 
1908                 if (check_creds) {
1909                         /* Never glue messages from different writers */
1910                         if ((UNIXCB(skb).pid  != siocb->scm->pid) ||
1911                             (UNIXCB(skb).cred != siocb->scm->cred)) {
1912                                 skb_queue_head(&sk->sk_receive_queue, skb);
1913                                 break;
1914                         }
1915                 } else {
1916                         /* Copy credentials */
1917                         scm_set_cred(siocb->scm, UNIXCB(skb).pid, UNIXCB(skb).cred);
1918                         check_creds = 1;
1919                 }
1920 
1921                 /* Copy address just once */
1922                 if (sunaddr) {
1923                         unix_copy_addr(msg, skb->sk);
1924                         sunaddr = NULL;
1925                 }
1926 
1927                 chunk = min_t(unsigned int, skb->len, size);
1928                 if (memcpy_toiovec(msg->msg_iov, skb->data, chunk)) {
1929                         skb_queue_head(&sk->sk_receive_queue, skb);
1930                         if (copied == 0)
1931                                 copied = -EFAULT;
1932                         break;
1933                 }
1934                 copied += chunk;
1935                 size -= chunk;
1936 
1937                 /* Mark read part of skb as used */
1938                 if (!(flags & MSG_PEEK)) {
1939                         skb_pull(skb, chunk);
1940 
1941                         if (UNIXCB(skb).fp)
1942                                 unix_detach_fds(siocb->scm, skb);
1943 
1944                         /* put the skb back if we didn't use it up.. */
1945                         if (skb->len) {
1946                                 skb_queue_head(&sk->sk_receive_queue, skb);
1947                                 break;
1948                         }
1949 
1950                         consume_skb(skb);
1951 
1952                         if (siocb->scm->fp)
1953                                 break;
1954                 } else {
1955                         /* It is questionable, see note in unix_dgram_recvmsg.
1956                          */
1957                         if (UNIXCB(skb).fp)
1958                                 siocb->scm->fp = scm_fp_dup(UNIXCB(skb).fp);
1959 
1960                         /* put message back and return */
1961                         skb_queue_head(&sk->sk_receive_queue, skb);
1962                         break;
1963                 }
1964         } while (size);
1965 
1966         mutex_unlock(&u->readlock);
1967         scm_recv(sock, msg, siocb->scm, flags);
1968 out:
1969         return copied ? : err;
1970 }
1971 
1972 static int unix_shutdown(struct socket *sock, int mode)
1973 {
1974         struct sock *sk = sock->sk;
1975         struct sock *other;
1976 
1977         mode = (mode+1)&(RCV_SHUTDOWN|SEND_SHUTDOWN);
1978 
1979         if (mode) {
1980                 unix_state_lock(sk);
1981                 sk->sk_shutdown |= mode;
1982                 other = unix_peer(sk);
1983                 if (other)
1984                         sock_hold(other);
1985                 unix_state_unlock(sk);
1986                 sk->sk_state_change(sk);
1987 
1988                 if (other &&
1989                         (sk->sk_type == SOCK_STREAM || sk->sk_type == SOCK_SEQPACKET)) {
1990 
1991                         int peer_mode = 0;
1992 
1993                         if (mode&RCV_SHUTDOWN)
1994                                 peer_mode |= SEND_SHUTDOWN;
1995                         if (mode&SEND_SHUTDOWN)
1996                                 peer_mode |= RCV_SHUTDOWN;
1997                         unix_state_lock(other);
1998                         other->sk_shutdown |= peer_mode;
1999                         unix_state_unlock(other);
2000                         other->sk_state_change(other);
2001                         if (peer_mode == SHUTDOWN_MASK)
2002                                 sk_wake_async(other, SOCK_WAKE_WAITD, POLL_HUP);
2003                         else if (peer_mode & RCV_SHUTDOWN)
2004                                 sk_wake_async(other, SOCK_WAKE_WAITD, POLL_IN);
2005                 }
2006                 if (other)
2007                         sock_put(other);
2008         }
2009         return 0;
2010 }
2011 
2012 static int unix_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
2013 {
2014         struct sock *sk = sock->sk;
2015         long amount = 0;
2016         int err;
2017 
2018         switch (cmd) {
2019         case SIOCOUTQ:
2020                 amount = sk_wmem_alloc_get(sk);
2021                 err = put_user(amount, (int __user *)arg);
2022                 break;
2023         case SIOCINQ:
2024                 {
2025                         struct sk_buff *skb;
2026 
2027                         if (sk->sk_state == TCP_LISTEN) {
2028                                 err = -EINVAL;
2029                                 break;
2030                         }
2031 
2032                         spin_lock(&sk->sk_receive_queue.lock);
2033                         if (sk->sk_type == SOCK_STREAM ||
2034                             sk->sk_type == SOCK_SEQPACKET) {
2035                                 skb_queue_walk(&sk->sk_receive_queue, skb)
2036                                         amount += skb->len;
2037                         } else {
2038                                 skb = skb_peek(&sk->sk_receive_queue);
2039                                 if (skb)
2040                                         amount = skb->len;
2041                         }
2042                         spin_unlock(&sk->sk_receive_queue.lock);
2043                         err = put_user(amount, (int __user *)arg);
2044                         break;
2045                 }
2046 
2047         default:
2048                 err = -ENOIOCTLCMD;
2049                 break;
2050         }
2051         return err;
2052 }
2053 
2054 static unsigned int unix_poll(struct file *file, struct socket *sock, poll_table *wait)
2055 {
2056         struct sock *sk = sock->sk;
2057         unsigned int mask;
2058 
2059         sock_poll_wait(file, sk_sleep(sk), wait);
2060         mask = 0;
2061 
2062         /* exceptional events? */
2063         if (sk->sk_err)
2064                 mask |= POLLERR;
2065         if (sk->sk_shutdown == SHUTDOWN_MASK)
2066                 mask |= POLLHUP;
2067         if (sk->sk_shutdown & RCV_SHUTDOWN)
2068                 mask |= POLLRDHUP | POLLIN | POLLRDNORM;
2069 
2070         /* readable? */
2071         if (!skb_queue_empty(&sk->sk_receive_queue))
2072                 mask |= POLLIN | POLLRDNORM;
2073 
2074         /* Connection-based need to check for termination and startup */
2075         if ((sk->sk_type == SOCK_STREAM || sk->sk_type == SOCK_SEQPACKET) &&
2076             sk->sk_state == TCP_CLOSE)
2077                 mask |= POLLHUP;
2078 
2079         /*
2080          * we set writable also when the other side has shut down the
2081          * connection. This prevents stuck sockets.
2082          */
2083         if (unix_writable(sk))
2084                 mask |= POLLOUT | POLLWRNORM | POLLWRBAND;
2085 
2086         return mask;
2087 }
2088 
2089 static unsigned int unix_dgram_poll(struct file *file, struct socket *sock,
2090                                     poll_table *wait)
2091 {
2092         struct sock *sk = sock->sk, *other;
2093         unsigned int mask, writable;
2094 
2095         sock_poll_wait(file, sk_sleep(sk), wait);
2096         mask = 0;
2097 
2098         /* exceptional events? */
2099         if (sk->sk_err || !skb_queue_empty(&sk->sk_error_queue))
2100                 mask |= POLLERR;
2101         if (sk->sk_shutdown & RCV_SHUTDOWN)
2102                 mask |= POLLRDHUP;
2103         if (sk->sk_shutdown == SHUTDOWN_MASK)
2104                 mask |= POLLHUP;
2105 
2106         /* readable? */
2107         if (!skb_queue_empty(&sk->sk_receive_queue) ||
2108             (sk->sk_shutdown & RCV_SHUTDOWN))
2109                 mask |= POLLIN | POLLRDNORM;
2110 
2111         /* Connection-based need to check for termination and startup */
2112         if (sk->sk_type == SOCK_SEQPACKET) {
2113                 if (sk->sk_state == TCP_CLOSE)
2114                         mask |= POLLHUP;
2115                 /* connection hasn't started yet? */
2116                 if (sk->sk_state == TCP_SYN_SENT)
2117                         return mask;
2118         }
2119 
2120         /* writable? */
2121         writable = unix_writable(sk);
2122         if (writable) {
2123                 other = unix_peer_get(sk);
2124                 if (other) {
2125                         if (unix_peer(other) != sk) {
2126                                 sock_poll_wait(file, &unix_sk(other)->peer_wait,
2127                                           wait);
2128                                 if (unix_recvq_full(other))
2129                                         writable = 0;
2130                         }
2131 
2132                         sock_put(other);
2133                 }
2134         }
2135 
2136         if (writable)
2137                 mask |= POLLOUT | POLLWRNORM | POLLWRBAND;
2138         else
2139                 set_bit(SOCK_ASYNC_NOSPACE, &sk->sk_socket->flags);
2140 
2141         return mask;
2142 }
2143 
2144 #ifdef CONFIG_PROC_FS
2145 static struct sock *first_unix_socket(int *i)
2146 {
2147         for (*i = 0; *i <= UNIX_HASH_SIZE; (*i)++) {
2148                 if (!hlist_empty(&unix_socket_table[*i]))
2149                         return __sk_head(&unix_socket_table[*i]);
2150         }
2151         return NULL;
2152 }
2153 
2154 static struct sock *next_unix_socket(int *i, struct sock *s)
2155 {
2156         struct sock *next = sk_next(s);
2157         /* More in this chain? */
2158         if (next)
2159                 return next;
2160         /* Look for next non-empty chain. */
2161         for ((*i)++; *i <= UNIX_HASH_SIZE; (*i)++) {
2162                 if (!hlist_empty(&unix_socket_table[*i]))
2163                         return __sk_head(&unix_socket_table[*i]);
2164         }
2165         return NULL;
2166 }
2167 
2168 struct unix_iter_state {
2169         struct seq_net_private p;
2170         int i;
2171 };
2172 
2173 static struct sock *unix_seq_idx(struct seq_file *seq, loff_t pos)
2174 {
2175         struct unix_iter_state *iter = seq->private;
2176         loff_t off = 0;
2177         struct sock *s;
2178 
2179         for (s = first_unix_socket(&iter->i); s; s = next_unix_socket(&iter->i, s)) {
2180                 if (sock_net(s) != seq_file_net(seq))
2181                         continue;
2182                 if (off == pos)
2183                         return s;
2184                 ++off;
2185         }
2186         return NULL;
2187 }
2188 
2189 static void *unix_seq_start(struct seq_file *seq, loff_t *pos)
2190         __acquires(unix_table_lock)
2191 {
2192         spin_lock(&unix_table_lock);
2193         return *pos ? unix_seq_idx(seq, *pos - 1) : SEQ_START_TOKEN;
2194 }
2195 
2196 static void *unix_seq_next(struct seq_file *seq, void *v, loff_t *pos)
2197 {
2198         struct unix_iter_state *iter = seq->private;
2199         struct sock *sk = v;
2200         ++*pos;
2201 
2202         if (v == SEQ_START_TOKEN)
2203                 sk = first_unix_socket(&iter->i);
2204         else
2205                 sk = next_unix_socket(&iter->i, sk);
2206         while (sk && (sock_net(sk) != seq_file_net(seq)))
2207                 sk = next_unix_socket(&iter->i, sk);
2208         return sk;
2209 }
2210 
2211 static void unix_seq_stop(struct seq_file *seq, void *v)
2212         __releases(unix_table_lock)
2213 {
2214         spin_unlock(&unix_table_lock);
2215 }
2216 
2217 static int unix_seq_show(struct seq_file *seq, void *v)
2218 {
2219 
2220         if (v == SEQ_START_TOKEN)
2221                 seq_puts(seq, "Num       RefCount Protocol Flags    Type St "
2222                          "Inode Path\n");
2223         else {
2224                 struct sock *s = v;
2225                 struct unix_sock *u = unix_sk(s);
2226                 unix_state_lock(s);
2227 
2228                 seq_printf(seq, "%p: %08X %08X %08X %04X %02X %5lu",
2229                         s,
2230                         atomic_read(&s->sk_refcnt),
2231                         0,
2232                         s->sk_state == TCP_LISTEN ? __SO_ACCEPTCON : 0,
2233                         s->sk_type,
2234                         s->sk_socket ?
2235                         (s->sk_state == TCP_ESTABLISHED ? SS_CONNECTED : SS_UNCONNECTED) :
2236                         (s->sk_state == TCP_ESTABLISHED ? SS_CONNECTING : SS_DISCONNECTING),
2237                         sock_i_ino(s));
2238 
2239                 if (u->addr) {
2240                         int i, len;
2241                         seq_putc(seq, ' ');
2242 
2243                         i = 0;
2244                         len = u->addr->len - sizeof(short);
2245                         if (!UNIX_ABSTRACT(s))
2246                                 len--;
2247                         else {
2248                                 seq_putc(seq, '@');
2249                                 i++;
2250                         }
2251                         for ( ; i < len; i++)
2252                                 seq_putc(seq, u->addr->name->sun_path[i]);
2253                 }
2254                 unix_state_unlock(s);
2255                 seq_putc(seq, '\n');
2256         }
2257 
2258         return 0;
2259 }
2260 
2261 static const struct seq_operations unix_seq_ops = {
2262         .start  = unix_seq_start,
2263         .next   = unix_seq_next,
2264         .stop   = unix_seq_stop,
2265         .show   = unix_seq_show,
2266 };
2267 
2268 static int unix_seq_open(struct inode *inode, struct file *file)
2269 {
2270         return seq_open_net(inode, file, &unix_seq_ops,
2271                             sizeof(struct unix_iter_state));
2272 }
2273 
2274 static const struct file_operations unix_seq_fops = {
2275         .owner          = THIS_MODULE,
2276         .open           = unix_seq_open,
2277         .read           = seq_read,
2278         .llseek         = seq_lseek,
2279         .release        = seq_release_net,
2280 };
2281 
2282 #endif
2283 
2284 static const struct net_proto_family unix_family_ops = {
2285         .family = PF_UNIX,
2286         .create = unix_create,
2287         .owner  = THIS_MODULE,
2288 };
2289 
2290 
2291 static int __net_init unix_net_init(struct net *net)
2292 {
2293         int error = -ENOMEM;
2294 
2295         net->unx.sysctl_max_dgram_qlen = 10;
2296         if (unix_sysctl_register(net))
2297                 goto out;
2298 
2299 #ifdef CONFIG_PROC_FS
2300         if (!proc_net_fops_create(net, "unix", 0, &unix_seq_fops)) {
2301                 unix_sysctl_unregister(net);
2302                 goto out;
2303         }
2304 #endif
2305         error = 0;
2306 out:
2307         return error;
2308 }
2309 
2310 static void __net_exit unix_net_exit(struct net *net)
2311 {
2312         unix_sysctl_unregister(net);
2313         proc_net_remove(net, "unix");
2314 }
2315 
2316 static struct pernet_operations unix_net_ops = {
2317         .init = unix_net_init,
2318         .exit = unix_net_exit,
2319 };
2320 
2321 static int __init af_unix_init(void)
2322 {
2323         int rc = -1;
2324         struct sk_buff *dummy_skb;
2325 
2326         BUILD_BUG_ON(sizeof(struct unix_skb_parms) > sizeof(dummy_skb->cb));
2327 
2328         rc = proto_register(&unix_proto, 1);
2329         if (rc != 0) {
2330                 printk(KERN_CRIT "%s: Cannot create unix_sock SLAB cache!\n",
2331                        __func__);
2332                 goto out;
2333         }
2334 
2335         sock_register(&unix_family_ops);
2336         register_pernet_subsys(&unix_net_ops);
2337 out:
2338         return rc;
2339 }
2340 
2341 static void __exit af_unix_exit(void)
2342 {
2343         sock_unregister(PF_UNIX);
2344         proto_unregister(&unix_proto);
2345         unregister_pernet_subsys(&unix_net_ops);
2346 }
2347 
2348 /* Earlier than device_initcall() so that other drivers invoking
2349    request_module() don't end up in a loop when modprobe tries
2350    to use a UNIX socket. But later than subsys_initcall() because
2351    we depend on stuff initialised there */
2352 fs_initcall(af_unix_init);
2353 module_exit(af_unix_exit);
2354 
2355 MODULE_LICENSE("GPL");
2356 MODULE_ALIAS_NETPROTO(PF_UNIX);
2357 

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