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