1 /* -*- c -*- --------------------------------------------------------------- *
2 *
3 * linux/fs/autofs/waitq.c
4 *
5 * Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
6 * Copyright 2001-2006 Ian Kent <raven@themaw.net>
7 *
8 * This file is part of the Linux kernel and is made available under
9 * the terms of the GNU General Public License, version 2, or at your
10 * option, any later version, incorporated herein by reference.
11 *
12 * ------------------------------------------------------------------------- */
13
14 #include <linux/slab.h>
15 #include <linux/time.h>
16 #include <linux/signal.h>
17 #include <linux/file.h>
18 #include "autofs_i.h"
19
20 /* We make this a static variable rather than a part of the superblock; it
21 is better if we don't reassign numbers easily even across filesystems */
22 static autofs_wqt_t autofs4_next_wait_queue = 1;
23
24 /* These are the signals we allow interrupting a pending mount */
25 #define SHUTDOWN_SIGS (sigmask(SIGKILL) | sigmask(SIGINT) | sigmask(SIGQUIT))
26
autofs4_catatonic_mode(struct autofs_sb_info * sbi)27 void autofs4_catatonic_mode(struct autofs_sb_info *sbi)
28 {
29 struct autofs_wait_queue *wq, *nwq;
30
31 mutex_lock(&sbi->wq_mutex);
32 if (sbi->catatonic) {
33 mutex_unlock(&sbi->wq_mutex);
34 return;
35 }
36
37 DPRINTK("entering catatonic mode");
38
39 sbi->catatonic = 1;
40 wq = sbi->queues;
41 sbi->queues = NULL; /* Erase all wait queues */
42 while (wq) {
43 nwq = wq->next;
44 wq->status = -ENOENT; /* Magic is gone - report failure */
45 kfree(wq->name.name);
46 wq->name.name = NULL;
47 wq->wait_ctr--;
48 wake_up_interruptible(&wq->queue);
49 wq = nwq;
50 }
51 fput(sbi->pipe); /* Close the pipe */
52 sbi->pipe = NULL;
53 sbi->pipefd = -1;
54 mutex_unlock(&sbi->wq_mutex);
55 }
56
autofs4_write(struct autofs_sb_info * sbi,struct file * file,const void * addr,int bytes)57 static int autofs4_write(struct autofs_sb_info *sbi,
58 struct file *file, const void *addr, int bytes)
59 {
60 unsigned long sigpipe, flags;
61 mm_segment_t fs;
62 const char *data = (const char *)addr;
63 ssize_t wr = 0;
64
65 sigpipe = sigismember(¤t->pending.signal, SIGPIPE);
66
67 /* Save pointer to user space and point back to kernel space */
68 fs = get_fs();
69 set_fs(KERNEL_DS);
70
71 mutex_lock(&sbi->pipe_mutex);
72 while (bytes &&
73 (wr = __vfs_write(file,data,bytes,&file->f_pos)) > 0) {
74 data += wr;
75 bytes -= wr;
76 }
77 mutex_unlock(&sbi->pipe_mutex);
78
79 set_fs(fs);
80
81 /* Keep the currently executing process from receiving a
82 SIGPIPE unless it was already supposed to get one */
83 if (wr == -EPIPE && !sigpipe) {
84 spin_lock_irqsave(¤t->sighand->siglock, flags);
85 sigdelset(¤t->pending.signal, SIGPIPE);
86 recalc_sigpending();
87 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
88 }
89
90 /* if 'wr' returned 0 (impossible) we assume -EIO (safe) */
91 return bytes == 0 ? 0 : wr < 0 ? wr : -EIO;
92 }
93
autofs4_notify_daemon(struct autofs_sb_info * sbi,struct autofs_wait_queue * wq,int type)94 static void autofs4_notify_daemon(struct autofs_sb_info *sbi,
95 struct autofs_wait_queue *wq,
96 int type)
97 {
98 union {
99 struct autofs_packet_hdr hdr;
100 union autofs_packet_union v4_pkt;
101 union autofs_v5_packet_union v5_pkt;
102 } pkt;
103 struct file *pipe = NULL;
104 size_t pktsz;
105 int ret;
106
107 DPRINTK("wait id = 0x%08lx, name = %.*s, type=%d",
108 (unsigned long) wq->wait_queue_token, wq->name.len, wq->name.name, type);
109
110 memset(&pkt,0,sizeof pkt); /* For security reasons */
111
112 pkt.hdr.proto_version = sbi->version;
113 pkt.hdr.type = type;
114
115 switch (type) {
116 /* Kernel protocol v4 missing and expire packets */
117 case autofs_ptype_missing:
118 {
119 struct autofs_packet_missing *mp = &pkt.v4_pkt.missing;
120
121 pktsz = sizeof(*mp);
122
123 mp->wait_queue_token = wq->wait_queue_token;
124 mp->len = wq->name.len;
125 memcpy(mp->name, wq->name.name, wq->name.len);
126 mp->name[wq->name.len] = '\0';
127 break;
128 }
129 case autofs_ptype_expire_multi:
130 {
131 struct autofs_packet_expire_multi *ep = &pkt.v4_pkt.expire_multi;
132
133 pktsz = sizeof(*ep);
134
135 ep->wait_queue_token = wq->wait_queue_token;
136 ep->len = wq->name.len;
137 memcpy(ep->name, wq->name.name, wq->name.len);
138 ep->name[wq->name.len] = '\0';
139 break;
140 }
141 /*
142 * Kernel protocol v5 packet for handling indirect and direct
143 * mount missing and expire requests
144 */
145 case autofs_ptype_missing_indirect:
146 case autofs_ptype_expire_indirect:
147 case autofs_ptype_missing_direct:
148 case autofs_ptype_expire_direct:
149 {
150 struct autofs_v5_packet *packet = &pkt.v5_pkt.v5_packet;
151 struct user_namespace *user_ns = sbi->pipe->f_cred->user_ns;
152
153 pktsz = sizeof(*packet);
154
155 packet->wait_queue_token = wq->wait_queue_token;
156 packet->len = wq->name.len;
157 memcpy(packet->name, wq->name.name, wq->name.len);
158 packet->name[wq->name.len] = '\0';
159 packet->dev = wq->dev;
160 packet->ino = wq->ino;
161 packet->uid = from_kuid_munged(user_ns, wq->uid);
162 packet->gid = from_kgid_munged(user_ns, wq->gid);
163 packet->pid = wq->pid;
164 packet->tgid = wq->tgid;
165 break;
166 }
167 default:
168 printk("autofs4_notify_daemon: bad type %d!\n", type);
169 mutex_unlock(&sbi->wq_mutex);
170 return;
171 }
172
173 pipe = get_file(sbi->pipe);
174
175 mutex_unlock(&sbi->wq_mutex);
176
177 switch (ret = autofs4_write(sbi, pipe, &pkt, pktsz)) {
178 case 0:
179 break;
180 case -ENOMEM:
181 case -ERESTARTSYS:
182 /* Just fail this one */
183 autofs4_wait_release(sbi, wq->wait_queue_token, ret);
184 break;
185 default:
186 autofs4_catatonic_mode(sbi);
187 break;
188 }
189 fput(pipe);
190 }
191
autofs4_getpath(struct autofs_sb_info * sbi,struct dentry * dentry,char ** name)192 static int autofs4_getpath(struct autofs_sb_info *sbi,
193 struct dentry *dentry, char **name)
194 {
195 struct dentry *root = sbi->sb->s_root;
196 struct dentry *tmp;
197 char *buf;
198 char *p;
199 int len;
200 unsigned seq;
201
202 rename_retry:
203 buf = *name;
204 len = 0;
205
206 seq = read_seqbegin(&rename_lock);
207 rcu_read_lock();
208 spin_lock(&sbi->fs_lock);
209 for (tmp = dentry ; tmp != root ; tmp = tmp->d_parent)
210 len += tmp->d_name.len + 1;
211
212 if (!len || --len > NAME_MAX) {
213 spin_unlock(&sbi->fs_lock);
214 rcu_read_unlock();
215 if (read_seqretry(&rename_lock, seq))
216 goto rename_retry;
217 return 0;
218 }
219
220 *(buf + len) = '\0';
221 p = buf + len - dentry->d_name.len;
222 strncpy(p, dentry->d_name.name, dentry->d_name.len);
223
224 for (tmp = dentry->d_parent; tmp != root ; tmp = tmp->d_parent) {
225 *(--p) = '/';
226 p -= tmp->d_name.len;
227 strncpy(p, tmp->d_name.name, tmp->d_name.len);
228 }
229 spin_unlock(&sbi->fs_lock);
230 rcu_read_unlock();
231 if (read_seqretry(&rename_lock, seq))
232 goto rename_retry;
233
234 return len;
235 }
236
237 static struct autofs_wait_queue *
autofs4_find_wait(struct autofs_sb_info * sbi,struct qstr * qstr)238 autofs4_find_wait(struct autofs_sb_info *sbi, struct qstr *qstr)
239 {
240 struct autofs_wait_queue *wq;
241
242 for (wq = sbi->queues; wq; wq = wq->next) {
243 if (wq->name.hash == qstr->hash &&
244 wq->name.len == qstr->len &&
245 wq->name.name &&
246 !memcmp(wq->name.name, qstr->name, qstr->len))
247 break;
248 }
249 return wq;
250 }
251
252 /*
253 * Check if we have a valid request.
254 * Returns
255 * 1 if the request should continue.
256 * In this case we can return an autofs_wait_queue entry if one is
257 * found or NULL to idicate a new wait needs to be created.
258 * 0 or a negative errno if the request shouldn't continue.
259 */
validate_request(struct autofs_wait_queue ** wait,struct autofs_sb_info * sbi,struct qstr * qstr,struct dentry * dentry,enum autofs_notify notify)260 static int validate_request(struct autofs_wait_queue **wait,
261 struct autofs_sb_info *sbi,
262 struct qstr *qstr,
263 struct dentry*dentry, enum autofs_notify notify)
264 {
265 struct autofs_wait_queue *wq;
266 struct autofs_info *ino;
267
268 if (sbi->catatonic)
269 return -ENOENT;
270
271 /* Wait in progress, continue; */
272 wq = autofs4_find_wait(sbi, qstr);
273 if (wq) {
274 *wait = wq;
275 return 1;
276 }
277
278 *wait = NULL;
279
280 /* If we don't yet have any info this is a new request */
281 ino = autofs4_dentry_ino(dentry);
282 if (!ino)
283 return 1;
284
285 /*
286 * If we've been asked to wait on an existing expire (NFY_NONE)
287 * but there is no wait in the queue ...
288 */
289 if (notify == NFY_NONE) {
290 /*
291 * Either we've betean the pending expire to post it's
292 * wait or it finished while we waited on the mutex.
293 * So we need to wait till either, the wait appears
294 * or the expire finishes.
295 */
296
297 while (ino->flags & AUTOFS_INF_EXPIRING) {
298 mutex_unlock(&sbi->wq_mutex);
299 schedule_timeout_interruptible(HZ/10);
300 if (mutex_lock_interruptible(&sbi->wq_mutex))
301 return -EINTR;
302
303 if (sbi->catatonic)
304 return -ENOENT;
305
306 wq = autofs4_find_wait(sbi, qstr);
307 if (wq) {
308 *wait = wq;
309 return 1;
310 }
311 }
312
313 /*
314 * Not ideal but the status has already gone. Of the two
315 * cases where we wait on NFY_NONE neither depend on the
316 * return status of the wait.
317 */
318 return 0;
319 }
320
321 /*
322 * If we've been asked to trigger a mount and the request
323 * completed while we waited on the mutex ...
324 */
325 if (notify == NFY_MOUNT) {
326 struct dentry *new = NULL;
327 int valid = 1;
328
329 /*
330 * If the dentry was successfully mounted while we slept
331 * on the wait queue mutex we can return success. If it
332 * isn't mounted (doesn't have submounts for the case of
333 * a multi-mount with no mount at it's base) we can
334 * continue on and create a new request.
335 */
336 if (!IS_ROOT(dentry)) {
337 if (d_really_is_positive(dentry) && d_unhashed(dentry)) {
338 struct dentry *parent = dentry->d_parent;
339 new = d_lookup(parent, &dentry->d_name);
340 if (new)
341 dentry = new;
342 }
343 }
344 if (have_submounts(dentry))
345 valid = 0;
346
347 if (new)
348 dput(new);
349 return valid;
350 }
351
352 return 1;
353 }
354
autofs4_wait(struct autofs_sb_info * sbi,struct dentry * dentry,enum autofs_notify notify)355 int autofs4_wait(struct autofs_sb_info *sbi, struct dentry *dentry,
356 enum autofs_notify notify)
357 {
358 struct autofs_wait_queue *wq;
359 struct qstr qstr;
360 char *name;
361 int status, ret, type;
362 pid_t pid;
363 pid_t tgid;
364
365 /* In catatonic mode, we don't wait for nobody */
366 if (sbi->catatonic)
367 return -ENOENT;
368
369 /*
370 * Try translating pids to the namespace of the daemon.
371 *
372 * Zero means failure: we are in an unrelated pid namespace.
373 */
374 pid = task_pid_nr_ns(current, ns_of_pid(sbi->oz_pgrp));
375 tgid = task_tgid_nr_ns(current, ns_of_pid(sbi->oz_pgrp));
376 if (pid == 0 || tgid == 0)
377 return -ENOENT;
378
379 if (d_really_is_negative(dentry)) {
380 /*
381 * A wait for a negative dentry is invalid for certain
382 * cases. A direct or offset mount "always" has its mount
383 * point directory created and so the request dentry must
384 * be positive or the map key doesn't exist. The situation
385 * is very similar for indirect mounts except only dentrys
386 * in the root of the autofs file system may be negative.
387 */
388 if (autofs_type_trigger(sbi->type))
389 return -ENOENT;
390 else if (!IS_ROOT(dentry->d_parent))
391 return -ENOENT;
392 }
393
394 name = kmalloc(NAME_MAX + 1, GFP_KERNEL);
395 if (!name)
396 return -ENOMEM;
397
398 /* If this is a direct mount request create a dummy name */
399 if (IS_ROOT(dentry) && autofs_type_trigger(sbi->type))
400 qstr.len = sprintf(name, "%p", dentry);
401 else {
402 qstr.len = autofs4_getpath(sbi, dentry, &name);
403 if (!qstr.len) {
404 kfree(name);
405 return -ENOENT;
406 }
407 }
408 qstr.name = name;
409 qstr.hash = full_name_hash(name, qstr.len);
410
411 if (mutex_lock_interruptible(&sbi->wq_mutex)) {
412 kfree(qstr.name);
413 return -EINTR;
414 }
415
416 ret = validate_request(&wq, sbi, &qstr, dentry, notify);
417 if (ret <= 0) {
418 if (ret != -EINTR)
419 mutex_unlock(&sbi->wq_mutex);
420 kfree(qstr.name);
421 return ret;
422 }
423
424 if (!wq) {
425 /* Create a new wait queue */
426 wq = kmalloc(sizeof(struct autofs_wait_queue),GFP_KERNEL);
427 if (!wq) {
428 kfree(qstr.name);
429 mutex_unlock(&sbi->wq_mutex);
430 return -ENOMEM;
431 }
432
433 wq->wait_queue_token = autofs4_next_wait_queue;
434 if (++autofs4_next_wait_queue == 0)
435 autofs4_next_wait_queue = 1;
436 wq->next = sbi->queues;
437 sbi->queues = wq;
438 init_waitqueue_head(&wq->queue);
439 memcpy(&wq->name, &qstr, sizeof(struct qstr));
440 wq->dev = autofs4_get_dev(sbi);
441 wq->ino = autofs4_get_ino(sbi);
442 wq->uid = current_uid();
443 wq->gid = current_gid();
444 wq->pid = pid;
445 wq->tgid = tgid;
446 wq->status = -EINTR; /* Status return if interrupted */
447 wq->wait_ctr = 2;
448
449 if (sbi->version < 5) {
450 if (notify == NFY_MOUNT)
451 type = autofs_ptype_missing;
452 else
453 type = autofs_ptype_expire_multi;
454 } else {
455 if (notify == NFY_MOUNT)
456 type = autofs_type_trigger(sbi->type) ?
457 autofs_ptype_missing_direct :
458 autofs_ptype_missing_indirect;
459 else
460 type = autofs_type_trigger(sbi->type) ?
461 autofs_ptype_expire_direct :
462 autofs_ptype_expire_indirect;
463 }
464
465 DPRINTK("new wait id = 0x%08lx, name = %.*s, nfy=%d\n",
466 (unsigned long) wq->wait_queue_token, wq->name.len,
467 wq->name.name, notify);
468
469 /* autofs4_notify_daemon() may block; it will unlock ->wq_mutex */
470 autofs4_notify_daemon(sbi, wq, type);
471 } else {
472 wq->wait_ctr++;
473 DPRINTK("existing wait id = 0x%08lx, name = %.*s, nfy=%d",
474 (unsigned long) wq->wait_queue_token, wq->name.len,
475 wq->name.name, notify);
476 mutex_unlock(&sbi->wq_mutex);
477 kfree(qstr.name);
478 }
479
480 /*
481 * wq->name.name is NULL iff the lock is already released
482 * or the mount has been made catatonic.
483 */
484 if (wq->name.name) {
485 /* Block all but "shutdown" signals while waiting */
486 sigset_t oldset;
487 unsigned long irqflags;
488
489 spin_lock_irqsave(¤t->sighand->siglock, irqflags);
490 oldset = current->blocked;
491 siginitsetinv(¤t->blocked, SHUTDOWN_SIGS & ~oldset.sig[0]);
492 recalc_sigpending();
493 spin_unlock_irqrestore(¤t->sighand->siglock, irqflags);
494
495 wait_event_interruptible(wq->queue, wq->name.name == NULL);
496
497 spin_lock_irqsave(¤t->sighand->siglock, irqflags);
498 current->blocked = oldset;
499 recalc_sigpending();
500 spin_unlock_irqrestore(¤t->sighand->siglock, irqflags);
501 } else {
502 DPRINTK("skipped sleeping");
503 }
504
505 status = wq->status;
506
507 /*
508 * For direct and offset mounts we need to track the requester's
509 * uid and gid in the dentry info struct. This is so it can be
510 * supplied, on request, by the misc device ioctl interface.
511 * This is needed during daemon resatart when reconnecting
512 * to existing, active, autofs mounts. The uid and gid (and
513 * related string values) may be used for macro substitution
514 * in autofs mount maps.
515 */
516 if (!status) {
517 struct autofs_info *ino;
518 struct dentry *de = NULL;
519
520 /* direct mount or browsable map */
521 ino = autofs4_dentry_ino(dentry);
522 if (!ino) {
523 /* If not lookup actual dentry used */
524 de = d_lookup(dentry->d_parent, &dentry->d_name);
525 if (de)
526 ino = autofs4_dentry_ino(de);
527 }
528
529 /* Set mount requester */
530 if (ino) {
531 spin_lock(&sbi->fs_lock);
532 ino->uid = wq->uid;
533 ino->gid = wq->gid;
534 spin_unlock(&sbi->fs_lock);
535 }
536
537 if (de)
538 dput(de);
539 }
540
541 /* Are we the last process to need status? */
542 mutex_lock(&sbi->wq_mutex);
543 if (!--wq->wait_ctr)
544 kfree(wq);
545 mutex_unlock(&sbi->wq_mutex);
546
547 return status;
548 }
549
550
autofs4_wait_release(struct autofs_sb_info * sbi,autofs_wqt_t wait_queue_token,int status)551 int autofs4_wait_release(struct autofs_sb_info *sbi, autofs_wqt_t wait_queue_token, int status)
552 {
553 struct autofs_wait_queue *wq, **wql;
554
555 mutex_lock(&sbi->wq_mutex);
556 for (wql = &sbi->queues; (wq = *wql) != NULL; wql = &wq->next) {
557 if (wq->wait_queue_token == wait_queue_token)
558 break;
559 }
560
561 if (!wq) {
562 mutex_unlock(&sbi->wq_mutex);
563 return -EINVAL;
564 }
565
566 *wql = wq->next; /* Unlink from chain */
567 kfree(wq->name.name);
568 wq->name.name = NULL; /* Do not wait on this queue */
569 wq->status = status;
570 wake_up_interruptible(&wq->queue);
571 if (!--wq->wait_ctr)
572 kfree(wq);
573 mutex_unlock(&sbi->wq_mutex);
574
575 return 0;
576 }
577
578