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 */
19 static 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
autofs4_catatonic_mode(struct autofs_sb_info * sbi)24 void 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
autofs4_write(struct autofs_sb_info * sbi,struct file * file,const void * addr,int bytes)54 static 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 while (bytes) {
70 wr = __vfs_write(file, data, bytes, &file->f_pos);
71 if (wr <= 0)
72 break;
73 data += wr;
74 bytes -= wr;
75 }
76 mutex_unlock(&sbi->pipe_mutex);
77
78 set_fs(fs);
79
80 /* Keep the currently executing process from receiving a
81 * SIGPIPE unless it was already supposed to get one
82 */
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 pr_debug("wait id = 0x%08lx, name = %.*s, type=%d\n",
108 (unsigned long) wq->wait_queue_token,
109 wq->name.len, wq->name.name, type);
110
111 memset(&pkt, 0, sizeof(pkt)); /* For security reasons */
112
113 pkt.hdr.proto_version = sbi->version;
114 pkt.hdr.type = type;
115
116 switch (type) {
117 /* Kernel protocol v4 missing and expire packets */
118 case autofs_ptype_missing:
119 {
120 struct autofs_packet_missing *mp = &pkt.v4_pkt.missing;
121
122 pktsz = sizeof(*mp);
123
124 mp->wait_queue_token = wq->wait_queue_token;
125 mp->len = wq->name.len;
126 memcpy(mp->name, wq->name.name, wq->name.len);
127 mp->name[wq->name.len] = '\0';
128 break;
129 }
130 case autofs_ptype_expire_multi:
131 {
132 struct autofs_packet_expire_multi *ep =
133 &pkt.v4_pkt.expire_multi;
134
135 pktsz = sizeof(*ep);
136
137 ep->wait_queue_token = wq->wait_queue_token;
138 ep->len = wq->name.len;
139 memcpy(ep->name, wq->name.name, wq->name.len);
140 ep->name[wq->name.len] = '\0';
141 break;
142 }
143 /*
144 * Kernel protocol v5 packet for handling indirect and direct
145 * mount missing and expire requests
146 */
147 case autofs_ptype_missing_indirect:
148 case autofs_ptype_expire_indirect:
149 case autofs_ptype_missing_direct:
150 case autofs_ptype_expire_direct:
151 {
152 struct autofs_v5_packet *packet = &pkt.v5_pkt.v5_packet;
153 struct user_namespace *user_ns = sbi->pipe->f_cred->user_ns;
154
155 pktsz = sizeof(*packet);
156
157 packet->wait_queue_token = wq->wait_queue_token;
158 packet->len = wq->name.len;
159 memcpy(packet->name, wq->name.name, wq->name.len);
160 packet->name[wq->name.len] = '\0';
161 packet->dev = wq->dev;
162 packet->ino = wq->ino;
163 packet->uid = from_kuid_munged(user_ns, wq->uid);
164 packet->gid = from_kgid_munged(user_ns, wq->gid);
165 packet->pid = wq->pid;
166 packet->tgid = wq->tgid;
167 break;
168 }
169 default:
170 pr_warn("bad type %d!\n", type);
171 mutex_unlock(&sbi->wq_mutex);
172 return;
173 }
174
175 pipe = get_file(sbi->pipe);
176
177 mutex_unlock(&sbi->wq_mutex);
178
179 switch (ret = autofs4_write(sbi, pipe, &pkt, pktsz)) {
180 case 0:
181 break;
182 case -ENOMEM:
183 case -ERESTARTSYS:
184 /* Just fail this one */
185 autofs4_wait_release(sbi, wq->wait_queue_token, ret);
186 break;
187 default:
188 autofs4_catatonic_mode(sbi);
189 break;
190 }
191 fput(pipe);
192 }
193
autofs4_getpath(struct autofs_sb_info * sbi,struct dentry * dentry,char ** name)194 static int autofs4_getpath(struct autofs_sb_info *sbi,
195 struct dentry *dentry, char **name)
196 {
197 struct dentry *root = sbi->sb->s_root;
198 struct dentry *tmp;
199 char *buf;
200 char *p;
201 int len;
202 unsigned seq;
203
204 rename_retry:
205 buf = *name;
206 len = 0;
207
208 seq = read_seqbegin(&rename_lock);
209 rcu_read_lock();
210 spin_lock(&sbi->fs_lock);
211 for (tmp = dentry ; tmp != root ; tmp = tmp->d_parent)
212 len += tmp->d_name.len + 1;
213
214 if (!len || --len > NAME_MAX) {
215 spin_unlock(&sbi->fs_lock);
216 rcu_read_unlock();
217 if (read_seqretry(&rename_lock, seq))
218 goto rename_retry;
219 return 0;
220 }
221
222 *(buf + len) = '\0';
223 p = buf + len - dentry->d_name.len;
224 strncpy(p, dentry->d_name.name, dentry->d_name.len);
225
226 for (tmp = dentry->d_parent; tmp != root ; tmp = tmp->d_parent) {
227 *(--p) = '/';
228 p -= tmp->d_name.len;
229 strncpy(p, tmp->d_name.name, tmp->d_name.len);
230 }
231 spin_unlock(&sbi->fs_lock);
232 rcu_read_unlock();
233 if (read_seqretry(&rename_lock, seq))
234 goto rename_retry;
235
236 return len;
237 }
238
239 static struct autofs_wait_queue *
autofs4_find_wait(struct autofs_sb_info * sbi,const struct qstr * qstr)240 autofs4_find_wait(struct autofs_sb_info *sbi, const struct qstr *qstr)
241 {
242 struct autofs_wait_queue *wq;
243
244 for (wq = sbi->queues; wq; wq = wq->next) {
245 if (wq->name.hash == qstr->hash &&
246 wq->name.len == qstr->len &&
247 wq->name.name &&
248 !memcmp(wq->name.name, qstr->name, qstr->len))
249 break;
250 }
251 return wq;
252 }
253
254 /*
255 * Check if we have a valid request.
256 * Returns
257 * 1 if the request should continue.
258 * In this case we can return an autofs_wait_queue entry if one is
259 * found or NULL to idicate a new wait needs to be created.
260 * 0 or a negative errno if the request shouldn't continue.
261 */
validate_request(struct autofs_wait_queue ** wait,struct autofs_sb_info * sbi,const struct qstr * qstr,struct dentry * dentry,enum autofs_notify notify)262 static int validate_request(struct autofs_wait_queue **wait,
263 struct autofs_sb_info *sbi,
264 const struct qstr *qstr,
265 struct dentry *dentry, enum autofs_notify notify)
266 {
267 struct autofs_wait_queue *wq;
268 struct autofs_info *ino;
269
270 if (sbi->catatonic)
271 return -ENOENT;
272
273 /* Wait in progress, continue; */
274 wq = autofs4_find_wait(sbi, qstr);
275 if (wq) {
276 *wait = wq;
277 return 1;
278 }
279
280 *wait = NULL;
281
282 /* If we don't yet have any info this is a new request */
283 ino = autofs4_dentry_ino(dentry);
284 if (!ino)
285 return 1;
286
287 /*
288 * If we've been asked to wait on an existing expire (NFY_NONE)
289 * but there is no wait in the queue ...
290 */
291 if (notify == NFY_NONE) {
292 /*
293 * Either we've betean the pending expire to post it's
294 * wait or it finished while we waited on the mutex.
295 * So we need to wait till either, the wait appears
296 * or the expire finishes.
297 */
298
299 while (ino->flags & AUTOFS_INF_EXPIRING) {
300 mutex_unlock(&sbi->wq_mutex);
301 schedule_timeout_interruptible(HZ/10);
302 if (mutex_lock_interruptible(&sbi->wq_mutex))
303 return -EINTR;
304
305 if (sbi->catatonic)
306 return -ENOENT;
307
308 wq = autofs4_find_wait(sbi, qstr);
309 if (wq) {
310 *wait = wq;
311 return 1;
312 }
313 }
314
315 /*
316 * Not ideal but the status has already gone. Of the two
317 * cases where we wait on NFY_NONE neither depend on the
318 * return status of the wait.
319 */
320 return 0;
321 }
322
323 /*
324 * If we've been asked to trigger a mount and the request
325 * completed while we waited on the mutex ...
326 */
327 if (notify == NFY_MOUNT) {
328 struct dentry *new = NULL;
329 int valid = 1;
330
331 /*
332 * If the dentry was successfully mounted while we slept
333 * on the wait queue mutex we can return success. If it
334 * isn't mounted (doesn't have submounts for the case of
335 * a multi-mount with no mount at it's base) we can
336 * continue on and create a new request.
337 */
338 if (!IS_ROOT(dentry)) {
339 if (d_unhashed(dentry) &&
340 d_really_is_positive(dentry)) {
341 struct dentry *parent = dentry->d_parent;
342
343 new = d_lookup(parent, &dentry->d_name);
344 if (new)
345 dentry = new;
346 }
347 }
348 if (have_submounts(dentry))
349 valid = 0;
350
351 if (new)
352 dput(new);
353 return valid;
354 }
355
356 return 1;
357 }
358
autofs4_wait(struct autofs_sb_info * sbi,struct dentry * dentry,enum autofs_notify notify)359 int autofs4_wait(struct autofs_sb_info *sbi,
360 struct dentry *dentry, enum autofs_notify notify)
361 {
362 struct autofs_wait_queue *wq;
363 struct qstr qstr;
364 char *name;
365 int status, ret, type;
366 pid_t pid;
367 pid_t tgid;
368
369 /* In catatonic mode, we don't wait for nobody */
370 if (sbi->catatonic)
371 return -ENOENT;
372
373 /*
374 * Try translating pids to the namespace of the daemon.
375 *
376 * Zero means failure: we are in an unrelated pid namespace.
377 */
378 pid = task_pid_nr_ns(current, ns_of_pid(sbi->oz_pgrp));
379 tgid = task_tgid_nr_ns(current, ns_of_pid(sbi->oz_pgrp));
380 if (pid == 0 || tgid == 0)
381 return -ENOENT;
382
383 if (d_really_is_negative(dentry)) {
384 /*
385 * A wait for a negative dentry is invalid for certain
386 * cases. A direct or offset mount "always" has its mount
387 * point directory created and so the request dentry must
388 * be positive or the map key doesn't exist. The situation
389 * is very similar for indirect mounts except only dentrys
390 * in the root of the autofs file system may be negative.
391 */
392 if (autofs_type_trigger(sbi->type))
393 return -ENOENT;
394 else if (!IS_ROOT(dentry->d_parent))
395 return -ENOENT;
396 }
397
398 name = kmalloc(NAME_MAX + 1, GFP_KERNEL);
399 if (!name)
400 return -ENOMEM;
401
402 /* If this is a direct mount request create a dummy name */
403 if (IS_ROOT(dentry) && autofs_type_trigger(sbi->type))
404 qstr.len = sprintf(name, "%p", dentry);
405 else {
406 qstr.len = autofs4_getpath(sbi, dentry, &name);
407 if (!qstr.len) {
408 kfree(name);
409 return -ENOENT;
410 }
411 }
412 qstr.name = name;
413 qstr.hash = full_name_hash(dentry, name, qstr.len);
414
415 if (mutex_lock_interruptible(&sbi->wq_mutex)) {
416 kfree(qstr.name);
417 return -EINTR;
418 }
419
420 ret = validate_request(&wq, sbi, &qstr, dentry, notify);
421 if (ret <= 0) {
422 if (ret != -EINTR)
423 mutex_unlock(&sbi->wq_mutex);
424 kfree(qstr.name);
425 return ret;
426 }
427
428 if (!wq) {
429 /* Create a new wait queue */
430 wq = kmalloc(sizeof(struct autofs_wait_queue), GFP_KERNEL);
431 if (!wq) {
432 kfree(qstr.name);
433 mutex_unlock(&sbi->wq_mutex);
434 return -ENOMEM;
435 }
436
437 wq->wait_queue_token = autofs4_next_wait_queue;
438 if (++autofs4_next_wait_queue == 0)
439 autofs4_next_wait_queue = 1;
440 wq->next = sbi->queues;
441 sbi->queues = wq;
442 init_waitqueue_head(&wq->queue);
443 memcpy(&wq->name, &qstr, sizeof(struct qstr));
444 wq->dev = autofs4_get_dev(sbi);
445 wq->ino = autofs4_get_ino(sbi);
446 wq->uid = current_cred()->uid;
447 wq->gid = current_cred()->gid;
448 wq->pid = pid;
449 wq->tgid = tgid;
450 wq->status = -EINTR; /* Status return if interrupted */
451 wq->wait_ctr = 2;
452
453 if (sbi->version < 5) {
454 if (notify == NFY_MOUNT)
455 type = autofs_ptype_missing;
456 else
457 type = autofs_ptype_expire_multi;
458 } else {
459 if (notify == NFY_MOUNT)
460 type = autofs_type_trigger(sbi->type) ?
461 autofs_ptype_missing_direct :
462 autofs_ptype_missing_indirect;
463 else
464 type = autofs_type_trigger(sbi->type) ?
465 autofs_ptype_expire_direct :
466 autofs_ptype_expire_indirect;
467 }
468
469 pr_debug("new wait id = 0x%08lx, name = %.*s, nfy=%d\n",
470 (unsigned long) wq->wait_queue_token, wq->name.len,
471 wq->name.name, notify);
472
473 /*
474 * autofs4_notify_daemon() may block; it will unlock ->wq_mutex
475 */
476 autofs4_notify_daemon(sbi, wq, type);
477 } else {
478 wq->wait_ctr++;
479 pr_debug("existing wait id = 0x%08lx, name = %.*s, nfy=%d\n",
480 (unsigned long) wq->wait_queue_token, wq->name.len,
481 wq->name.name, notify);
482 mutex_unlock(&sbi->wq_mutex);
483 kfree(qstr.name);
484 }
485
486 /*
487 * wq->name.name is NULL iff the lock is already released
488 * or the mount has been made catatonic.
489 */
490 if (wq->name.name) {
491 /* Block all but "shutdown" signals while waiting */
492 unsigned long shutdown_sigs_mask;
493 unsigned long irqflags;
494 sigset_t oldset;
495
496 spin_lock_irqsave(¤t->sighand->siglock, irqflags);
497 oldset = current->blocked;
498 shutdown_sigs_mask = SHUTDOWN_SIGS & ~oldset.sig[0];
499 siginitsetinv(¤t->blocked, shutdown_sigs_mask);
500 recalc_sigpending();
501 spin_unlock_irqrestore(¤t->sighand->siglock, irqflags);
502
503 wait_event_interruptible(wq->queue, wq->name.name == NULL);
504
505 spin_lock_irqsave(¤t->sighand->siglock, irqflags);
506 current->blocked = oldset;
507 recalc_sigpending();
508 spin_unlock_irqrestore(¤t->sighand->siglock, irqflags);
509 } else {
510 pr_debug("skipped sleeping\n");
511 }
512
513 status = wq->status;
514
515 /*
516 * For direct and offset mounts we need to track the requester's
517 * uid and gid in the dentry info struct. This is so it can be
518 * supplied, on request, by the misc device ioctl interface.
519 * This is needed during daemon resatart when reconnecting
520 * to existing, active, autofs mounts. The uid and gid (and
521 * related string values) may be used for macro substitution
522 * in autofs mount maps.
523 */
524 if (!status) {
525 struct autofs_info *ino;
526 struct dentry *de = NULL;
527
528 /* direct mount or browsable map */
529 ino = autofs4_dentry_ino(dentry);
530 if (!ino) {
531 /* If not lookup actual dentry used */
532 de = d_lookup(dentry->d_parent, &dentry->d_name);
533 if (de)
534 ino = autofs4_dentry_ino(de);
535 }
536
537 /* Set mount requester */
538 if (ino) {
539 spin_lock(&sbi->fs_lock);
540 ino->uid = wq->uid;
541 ino->gid = wq->gid;
542 spin_unlock(&sbi->fs_lock);
543 }
544
545 if (de)
546 dput(de);
547 }
548
549 /* Are we the last process to need status? */
550 mutex_lock(&sbi->wq_mutex);
551 if (!--wq->wait_ctr)
552 kfree(wq);
553 mutex_unlock(&sbi->wq_mutex);
554
555 return status;
556 }
557
558
autofs4_wait_release(struct autofs_sb_info * sbi,autofs_wqt_t wait_queue_token,int status)559 int autofs4_wait_release(struct autofs_sb_info *sbi, autofs_wqt_t wait_queue_token, int status)
560 {
561 struct autofs_wait_queue *wq, **wql;
562
563 mutex_lock(&sbi->wq_mutex);
564 for (wql = &sbi->queues; (wq = *wql) != NULL; wql = &wq->next) {
565 if (wq->wait_queue_token == wait_queue_token)
566 break;
567 }
568
569 if (!wq) {
570 mutex_unlock(&sbi->wq_mutex);
571 return -EINVAL;
572 }
573
574 *wql = wq->next; /* Unlink from chain */
575 kfree(wq->name.name);
576 wq->name.name = NULL; /* Do not wait on this queue */
577 wq->status = status;
578 wake_up_interruptible(&wq->queue);
579 if (!--wq->wait_ctr)
580 kfree(wq);
581 mutex_unlock(&sbi->wq_mutex);
582
583 return 0;
584 }
585