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 if (wq->name.name) {
46 kfree(wq->name.name);
47 wq->name.name = NULL;
48 }
49 wq->wait_ctr--;
50 wake_up_interruptible(&wq->queue);
51 wq = nwq;
52 }
53 fput(sbi->pipe); /* Close the pipe */
54 sbi->pipe = NULL;
55 sbi->pipefd = -1;
56 mutex_unlock(&sbi->wq_mutex);
57 }
58
autofs4_write(struct file * file,const void * addr,int bytes)59 static int autofs4_write(struct file *file, const void *addr, int bytes)
60 {
61 unsigned long sigpipe, flags;
62 mm_segment_t fs;
63 const char *data = (const char *)addr;
64 ssize_t wr = 0;
65
66 /** WARNING: this is not safe for writing more than PIPE_BUF bytes! **/
67
68 sigpipe = sigismember(¤t->pending.signal, SIGPIPE);
69
70 /* Save pointer to user space and point back to kernel space */
71 fs = get_fs();
72 set_fs(KERNEL_DS);
73
74 while (bytes &&
75 (wr = file->f_op->write(file,data,bytes,&file->f_pos)) > 0) {
76 data += wr;
77 bytes -= wr;
78 }
79
80 set_fs(fs);
81
82 /* Keep the currently executing process from receiving a
83 SIGPIPE unless it was already supposed to get one */
84 if (wr == -EPIPE && !sigpipe) {
85 spin_lock_irqsave(¤t->sighand->siglock, flags);
86 sigdelset(¤t->pending.signal, SIGPIPE);
87 recalc_sigpending();
88 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
89 }
90
91 return (bytes > 0);
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
106 DPRINTK("wait id = 0x%08lx, name = %.*s, type=%d",
107 wq->wait_queue_token, wq->name.len, wq->name.name, type);
108
109 memset(&pkt,0,sizeof pkt); /* For security reasons */
110
111 pkt.hdr.proto_version = sbi->version;
112 pkt.hdr.type = type;
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 = &pkt.v4_pkt.expire_multi;
130
131 pktsz = sizeof(*ep);
132
133 ep->wait_queue_token = wq->wait_queue_token;
134 ep->len = wq->name.len;
135 memcpy(ep->name, wq->name.name, wq->name.len);
136 ep->name[wq->name.len] = '\0';
137 break;
138 }
139 /*
140 * Kernel protocol v5 packet for handling indirect and direct
141 * mount missing and expire requests
142 */
143 case autofs_ptype_missing_indirect:
144 case autofs_ptype_expire_indirect:
145 case autofs_ptype_missing_direct:
146 case autofs_ptype_expire_direct:
147 {
148 struct autofs_v5_packet *packet = &pkt.v5_pkt.v5_packet;
149
150 pktsz = sizeof(*packet);
151
152 packet->wait_queue_token = wq->wait_queue_token;
153 packet->len = wq->name.len;
154 memcpy(packet->name, wq->name.name, wq->name.len);
155 packet->name[wq->name.len] = '\0';
156 packet->dev = wq->dev;
157 packet->ino = wq->ino;
158 packet->uid = wq->uid;
159 packet->gid = wq->gid;
160 packet->pid = wq->pid;
161 packet->tgid = wq->tgid;
162 break;
163 }
164 default:
165 printk("autofs4_notify_daemon: bad type %d!\n", type);
166 return;
167 }
168
169 /* Check if we have become catatonic */
170 mutex_lock(&sbi->wq_mutex);
171 if (!sbi->catatonic) {
172 pipe = sbi->pipe;
173 get_file(pipe);
174 }
175 mutex_unlock(&sbi->wq_mutex);
176
177 if (pipe) {
178 if (autofs4_write(pipe, &pkt, pktsz))
179 autofs4_catatonic_mode(sbi);
180 fput(pipe);
181 }
182 }
183
autofs4_getpath(struct autofs_sb_info * sbi,struct dentry * dentry,char ** name)184 static int autofs4_getpath(struct autofs_sb_info *sbi,
185 struct dentry *dentry, char **name)
186 {
187 struct dentry *root = sbi->sb->s_root;
188 struct dentry *tmp;
189 char *buf = *name;
190 char *p;
191 int len = 0;
192
193 spin_lock(&dcache_lock);
194 for (tmp = dentry ; tmp != root ; tmp = tmp->d_parent)
195 len += tmp->d_name.len + 1;
196
197 if (!len || --len > NAME_MAX) {
198 spin_unlock(&dcache_lock);
199 return 0;
200 }
201
202 *(buf + len) = '\0';
203 p = buf + len - dentry->d_name.len;
204 strncpy(p, dentry->d_name.name, dentry->d_name.len);
205
206 for (tmp = dentry->d_parent; tmp != root ; tmp = tmp->d_parent) {
207 *(--p) = '/';
208 p -= tmp->d_name.len;
209 strncpy(p, tmp->d_name.name, tmp->d_name.len);
210 }
211 spin_unlock(&dcache_lock);
212
213 return len;
214 }
215
216 static struct autofs_wait_queue *
autofs4_find_wait(struct autofs_sb_info * sbi,struct qstr * qstr)217 autofs4_find_wait(struct autofs_sb_info *sbi, struct qstr *qstr)
218 {
219 struct autofs_wait_queue *wq;
220
221 for (wq = sbi->queues; wq; wq = wq->next) {
222 if (wq->name.hash == qstr->hash &&
223 wq->name.len == qstr->len &&
224 wq->name.name &&
225 !memcmp(wq->name.name, qstr->name, qstr->len))
226 break;
227 }
228 return wq;
229 }
230
231 /*
232 * Check if we have a valid request.
233 * Returns
234 * 1 if the request should continue.
235 * In this case we can return an autofs_wait_queue entry if one is
236 * found or NULL to idicate a new wait needs to be created.
237 * 0 or a negative errno if the request shouldn't continue.
238 */
validate_request(struct autofs_wait_queue ** wait,struct autofs_sb_info * sbi,struct qstr * qstr,struct dentry * dentry,enum autofs_notify notify)239 static int validate_request(struct autofs_wait_queue **wait,
240 struct autofs_sb_info *sbi,
241 struct qstr *qstr,
242 struct dentry*dentry, enum autofs_notify notify)
243 {
244 struct autofs_wait_queue *wq;
245 struct autofs_info *ino;
246
247 /* Wait in progress, continue; */
248 wq = autofs4_find_wait(sbi, qstr);
249 if (wq) {
250 *wait = wq;
251 return 1;
252 }
253
254 *wait = NULL;
255
256 /* If we don't yet have any info this is a new request */
257 ino = autofs4_dentry_ino(dentry);
258 if (!ino)
259 return 1;
260
261 /*
262 * If we've been asked to wait on an existing expire (NFY_NONE)
263 * but there is no wait in the queue ...
264 */
265 if (notify == NFY_NONE) {
266 /*
267 * Either we've betean the pending expire to post it's
268 * wait or it finished while we waited on the mutex.
269 * So we need to wait till either, the wait appears
270 * or the expire finishes.
271 */
272
273 while (ino->flags & AUTOFS_INF_EXPIRING) {
274 mutex_unlock(&sbi->wq_mutex);
275 schedule_timeout_interruptible(HZ/10);
276 if (mutex_lock_interruptible(&sbi->wq_mutex))
277 return -EINTR;
278
279 wq = autofs4_find_wait(sbi, qstr);
280 if (wq) {
281 *wait = wq;
282 return 1;
283 }
284 }
285
286 /*
287 * Not ideal but the status has already gone. Of the two
288 * cases where we wait on NFY_NONE neither depend on the
289 * return status of the wait.
290 */
291 return 0;
292 }
293
294 /*
295 * If we've been asked to trigger a mount and the request
296 * completed while we waited on the mutex ...
297 */
298 if (notify == NFY_MOUNT) {
299 /*
300 * If the dentry isn't hashed just go ahead and try the
301 * mount again with a new wait (not much else we can do).
302 */
303 if (!d_unhashed(dentry)) {
304 /*
305 * But if the dentry is hashed, that means that we
306 * got here through the revalidate path. Thus, we
307 * need to check if the dentry has been mounted
308 * while we waited on the wq_mutex. If it has,
309 * simply return success.
310 */
311 if (d_mountpoint(dentry))
312 return 0;
313 }
314 }
315
316 return 1;
317 }
318
autofs4_wait(struct autofs_sb_info * sbi,struct dentry * dentry,enum autofs_notify notify)319 int autofs4_wait(struct autofs_sb_info *sbi, struct dentry *dentry,
320 enum autofs_notify notify)
321 {
322 struct autofs_wait_queue *wq;
323 struct qstr qstr;
324 char *name;
325 int status, ret, type;
326
327 /* In catatonic mode, we don't wait for nobody */
328 if (sbi->catatonic)
329 return -ENOENT;
330
331 if (!dentry->d_inode) {
332 /*
333 * A wait for a negative dentry is invalid for certain
334 * cases. A direct or offset mount "always" has its mount
335 * point directory created and so the request dentry must
336 * be positive or the map key doesn't exist. The situation
337 * is very similar for indirect mounts except only dentrys
338 * in the root of the autofs file system may be negative.
339 */
340 if (autofs_type_trigger(sbi->type))
341 return -ENOENT;
342 else if (!IS_ROOT(dentry->d_parent))
343 return -ENOENT;
344 }
345
346 name = kmalloc(NAME_MAX + 1, GFP_KERNEL);
347 if (!name)
348 return -ENOMEM;
349
350 /* If this is a direct mount request create a dummy name */
351 if (IS_ROOT(dentry) && autofs_type_trigger(sbi->type))
352 qstr.len = sprintf(name, "%p", dentry);
353 else {
354 qstr.len = autofs4_getpath(sbi, dentry, &name);
355 if (!qstr.len) {
356 kfree(name);
357 return -ENOENT;
358 }
359 }
360 qstr.name = name;
361 qstr.hash = full_name_hash(name, qstr.len);
362
363 if (mutex_lock_interruptible(&sbi->wq_mutex)) {
364 kfree(qstr.name);
365 return -EINTR;
366 }
367
368 ret = validate_request(&wq, sbi, &qstr, dentry, notify);
369 if (ret <= 0) {
370 if (ret == 0)
371 mutex_unlock(&sbi->wq_mutex);
372 kfree(qstr.name);
373 return ret;
374 }
375
376 if (!wq) {
377 /* Create a new wait queue */
378 wq = kmalloc(sizeof(struct autofs_wait_queue),GFP_KERNEL);
379 if (!wq) {
380 kfree(qstr.name);
381 mutex_unlock(&sbi->wq_mutex);
382 return -ENOMEM;
383 }
384
385 wq->wait_queue_token = autofs4_next_wait_queue;
386 if (++autofs4_next_wait_queue == 0)
387 autofs4_next_wait_queue = 1;
388 wq->next = sbi->queues;
389 sbi->queues = wq;
390 init_waitqueue_head(&wq->queue);
391 memcpy(&wq->name, &qstr, sizeof(struct qstr));
392 wq->dev = autofs4_get_dev(sbi);
393 wq->ino = autofs4_get_ino(sbi);
394 wq->uid = current_uid();
395 wq->gid = current_gid();
396 wq->pid = current->pid;
397 wq->tgid = current->tgid;
398 wq->status = -EINTR; /* Status return if interrupted */
399 wq->wait_ctr = 2;
400 mutex_unlock(&sbi->wq_mutex);
401
402 if (sbi->version < 5) {
403 if (notify == NFY_MOUNT)
404 type = autofs_ptype_missing;
405 else
406 type = autofs_ptype_expire_multi;
407 } else {
408 if (notify == NFY_MOUNT)
409 type = autofs_type_trigger(sbi->type) ?
410 autofs_ptype_missing_direct :
411 autofs_ptype_missing_indirect;
412 else
413 type = autofs_type_trigger(sbi->type) ?
414 autofs_ptype_expire_direct :
415 autofs_ptype_expire_indirect;
416 }
417
418 DPRINTK("new wait id = 0x%08lx, name = %.*s, nfy=%d\n",
419 (unsigned long) wq->wait_queue_token, wq->name.len,
420 wq->name.name, notify);
421
422 /* autofs4_notify_daemon() may block */
423 autofs4_notify_daemon(sbi, wq, type);
424 } else {
425 wq->wait_ctr++;
426 mutex_unlock(&sbi->wq_mutex);
427 kfree(qstr.name);
428 DPRINTK("existing wait id = 0x%08lx, name = %.*s, nfy=%d",
429 (unsigned long) wq->wait_queue_token, wq->name.len,
430 wq->name.name, notify);
431 }
432
433 /*
434 * wq->name.name is NULL iff the lock is already released
435 * or the mount has been made catatonic.
436 */
437 if (wq->name.name) {
438 /* Block all but "shutdown" signals while waiting */
439 sigset_t oldset;
440 unsigned long irqflags;
441
442 spin_lock_irqsave(¤t->sighand->siglock, irqflags);
443 oldset = current->blocked;
444 siginitsetinv(¤t->blocked, SHUTDOWN_SIGS & ~oldset.sig[0]);
445 recalc_sigpending();
446 spin_unlock_irqrestore(¤t->sighand->siglock, irqflags);
447
448 wait_event_interruptible(wq->queue, wq->name.name == NULL);
449
450 spin_lock_irqsave(¤t->sighand->siglock, irqflags);
451 current->blocked = oldset;
452 recalc_sigpending();
453 spin_unlock_irqrestore(¤t->sighand->siglock, irqflags);
454 } else {
455 DPRINTK("skipped sleeping");
456 }
457
458 status = wq->status;
459
460 /*
461 * For direct and offset mounts we need to track the requester's
462 * uid and gid in the dentry info struct. This is so it can be
463 * supplied, on request, by the misc device ioctl interface.
464 * This is needed during daemon resatart when reconnecting
465 * to existing, active, autofs mounts. The uid and gid (and
466 * related string values) may be used for macro substitution
467 * in autofs mount maps.
468 */
469 if (!status) {
470 struct autofs_info *ino;
471 struct dentry *de = NULL;
472
473 /* direct mount or browsable map */
474 ino = autofs4_dentry_ino(dentry);
475 if (!ino) {
476 /* If not lookup actual dentry used */
477 de = d_lookup(dentry->d_parent, &dentry->d_name);
478 if (de)
479 ino = autofs4_dentry_ino(de);
480 }
481
482 /* Set mount requester */
483 if (ino) {
484 spin_lock(&sbi->fs_lock);
485 ino->uid = wq->uid;
486 ino->gid = wq->gid;
487 spin_unlock(&sbi->fs_lock);
488 }
489
490 if (de)
491 dput(de);
492 }
493
494 /* Are we the last process to need status? */
495 mutex_lock(&sbi->wq_mutex);
496 if (!--wq->wait_ctr)
497 kfree(wq);
498 mutex_unlock(&sbi->wq_mutex);
499
500 return status;
501 }
502
503
autofs4_wait_release(struct autofs_sb_info * sbi,autofs_wqt_t wait_queue_token,int status)504 int autofs4_wait_release(struct autofs_sb_info *sbi, autofs_wqt_t wait_queue_token, int status)
505 {
506 struct autofs_wait_queue *wq, **wql;
507
508 mutex_lock(&sbi->wq_mutex);
509 for (wql = &sbi->queues; (wq = *wql) != NULL; wql = &wq->next) {
510 if (wq->wait_queue_token == wait_queue_token)
511 break;
512 }
513
514 if (!wq) {
515 mutex_unlock(&sbi->wq_mutex);
516 return -EINVAL;
517 }
518
519 *wql = wq->next; /* Unlink from chain */
520 kfree(wq->name.name);
521 wq->name.name = NULL; /* Do not wait on this queue */
522 wq->status = status;
523 wake_up_interruptible(&wq->queue);
524 if (!--wq->wait_ctr)
525 kfree(wq);
526 mutex_unlock(&sbi->wq_mutex);
527
528 return 0;
529 }
530
531