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