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1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
4 * Copyright 2001-2006 Ian Kent <raven@themaw.net>
5 */
6
7#include <linux/sched/signal.h>
8#include "autofs_i.h"
9
10/* We make this a static variable rather than a part of the superblock; it
11 * is better if we don't reassign numbers easily even across filesystems
12 */
13static autofs_wqt_t autofs_next_wait_queue = 1;
14
15void autofs_catatonic_mode(struct autofs_sb_info *sbi)
16{
17 struct autofs_wait_queue *wq, *nwq;
18
19 mutex_lock(&sbi->wq_mutex);
20 if (sbi->flags & AUTOFS_SBI_CATATONIC) {
21 mutex_unlock(&sbi->wq_mutex);
22 return;
23 }
24
25 pr_debug("entering catatonic mode\n");
26
27 sbi->flags |= AUTOFS_SBI_CATATONIC;
28 wq = sbi->queues;
29 sbi->queues = NULL; /* Erase all wait queues */
30 while (wq) {
31 nwq = wq->next;
32 wq->status = -ENOENT; /* Magic is gone - report failure */
33 kfree(wq->name.name - wq->offset);
34 wq->name.name = NULL;
35 wake_up(&wq->queue);
36 if (!--wq->wait_ctr)
37 kfree(wq);
38 wq = nwq;
39 }
40 fput(sbi->pipe); /* Close the pipe */
41 sbi->pipe = NULL;
42 sbi->pipefd = -1;
43 mutex_unlock(&sbi->wq_mutex);
44}
45
46static int autofs_write(struct autofs_sb_info *sbi,
47 struct file *file, const void *addr, int bytes)
48{
49 unsigned long sigpipe, flags;
50 const char *data = (const char *)addr;
51 ssize_t wr = 0;
52
53 sigpipe = sigismember(¤t->pending.signal, SIGPIPE);
54
55 mutex_lock(&sbi->pipe_mutex);
56 while (bytes) {
57 wr = __kernel_write(file, data, bytes, NULL);
58 if (wr <= 0)
59 break;
60 data += wr;
61 bytes -= wr;
62 }
63 mutex_unlock(&sbi->pipe_mutex);
64
65 /* Keep the currently executing process from receiving a
66 * SIGPIPE unless it was already supposed to get one
67 */
68 if (wr == -EPIPE && !sigpipe) {
69 spin_lock_irqsave(¤t->sighand->siglock, flags);
70 sigdelset(¤t->pending.signal, SIGPIPE);
71 recalc_sigpending();
72 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
73 }
74
75 /* if 'wr' returned 0 (impossible) we assume -EIO (safe) */
76 return bytes == 0 ? 0 : wr < 0 ? wr : -EIO;
77}
78
79static void autofs_notify_daemon(struct autofs_sb_info *sbi,
80 struct autofs_wait_queue *wq,
81 int type)
82{
83 union {
84 struct autofs_packet_hdr hdr;
85 union autofs_packet_union v4_pkt;
86 union autofs_v5_packet_union v5_pkt;
87 } pkt;
88 struct file *pipe = NULL;
89 size_t pktsz;
90 int ret;
91
92 pr_debug("wait id = 0x%08lx, name = %.*s, type=%d\n",
93 (unsigned long) wq->wait_queue_token,
94 wq->name.len, wq->name.name, type);
95
96 memset(&pkt, 0, sizeof(pkt)); /* For security reasons */
97
98 pkt.hdr.proto_version = sbi->version;
99 pkt.hdr.type = type;
100
101 switch (type) {
102 /* Kernel protocol v4 missing and expire packets */
103 case autofs_ptype_missing:
104 {
105 struct autofs_packet_missing *mp = &pkt.v4_pkt.missing;
106
107 pktsz = sizeof(*mp);
108
109 mp->wait_queue_token = wq->wait_queue_token;
110 mp->len = wq->name.len;
111 memcpy(mp->name, wq->name.name, wq->name.len);
112 mp->name[wq->name.len] = '\0';
113 break;
114 }
115 case autofs_ptype_expire_multi:
116 {
117 struct autofs_packet_expire_multi *ep =
118 &pkt.v4_pkt.expire_multi;
119
120 pktsz = sizeof(*ep);
121
122 ep->wait_queue_token = wq->wait_queue_token;
123 ep->len = wq->name.len;
124 memcpy(ep->name, wq->name.name, wq->name.len);
125 ep->name[wq->name.len] = '\0';
126 break;
127 }
128 /*
129 * Kernel protocol v5 packet for handling indirect and direct
130 * mount missing and expire requests
131 */
132 case autofs_ptype_missing_indirect:
133 case autofs_ptype_expire_indirect:
134 case autofs_ptype_missing_direct:
135 case autofs_ptype_expire_direct:
136 {
137 struct autofs_v5_packet *packet = &pkt.v5_pkt.v5_packet;
138 struct user_namespace *user_ns = sbi->pipe->f_cred->user_ns;
139
140 pktsz = sizeof(*packet);
141
142 packet->wait_queue_token = wq->wait_queue_token;
143 packet->len = wq->name.len;
144 memcpy(packet->name, wq->name.name, wq->name.len);
145 packet->name[wq->name.len] = '\0';
146 packet->dev = wq->dev;
147 packet->ino = wq->ino;
148 packet->uid = from_kuid_munged(user_ns, wq->uid);
149 packet->gid = from_kgid_munged(user_ns, wq->gid);
150 packet->pid = wq->pid;
151 packet->tgid = wq->tgid;
152 break;
153 }
154 default:
155 pr_warn("bad type %d!\n", type);
156 mutex_unlock(&sbi->wq_mutex);
157 return;
158 }
159
160 pipe = get_file(sbi->pipe);
161
162 mutex_unlock(&sbi->wq_mutex);
163
164 switch (ret = autofs_write(sbi, pipe, &pkt, pktsz)) {
165 case 0:
166 break;
167 case -ENOMEM:
168 case -ERESTARTSYS:
169 /* Just fail this one */
170 autofs_wait_release(sbi, wq->wait_queue_token, ret);
171 break;
172 default:
173 autofs_catatonic_mode(sbi);
174 break;
175 }
176 fput(pipe);
177}
178
179static struct autofs_wait_queue *
180autofs_find_wait(struct autofs_sb_info *sbi, const struct qstr *qstr)
181{
182 struct autofs_wait_queue *wq;
183
184 for (wq = sbi->queues; wq; wq = wq->next) {
185 if (wq->name.hash == qstr->hash &&
186 wq->name.len == qstr->len &&
187 wq->name.name &&
188 !memcmp(wq->name.name, qstr->name, qstr->len))
189 break;
190 }
191 return wq;
192}
193
194/*
195 * Check if we have a valid request.
196 * Returns
197 * 1 if the request should continue.
198 * In this case we can return an autofs_wait_queue entry if one is
199 * found or NULL to idicate a new wait needs to be created.
200 * 0 or a negative errno if the request shouldn't continue.
201 */
202static int validate_request(struct autofs_wait_queue **wait,
203 struct autofs_sb_info *sbi,
204 const struct qstr *qstr,
205 const struct path *path, enum autofs_notify notify)
206{
207 struct dentry *dentry = path->dentry;
208 struct autofs_wait_queue *wq;
209 struct autofs_info *ino;
210
211 if (sbi->flags & AUTOFS_SBI_CATATONIC)
212 return -ENOENT;
213
214 /* Wait in progress, continue; */
215 wq = autofs_find_wait(sbi, qstr);
216 if (wq) {
217 *wait = wq;
218 return 1;
219 }
220
221 *wait = NULL;
222
223 /* If we don't yet have any info this is a new request */
224 ino = autofs_dentry_ino(dentry);
225 if (!ino)
226 return 1;
227
228 /*
229 * If we've been asked to wait on an existing expire (NFY_NONE)
230 * but there is no wait in the queue ...
231 */
232 if (notify == NFY_NONE) {
233 /*
234 * Either we've betean the pending expire to post it's
235 * wait or it finished while we waited on the mutex.
236 * So we need to wait till either, the wait appears
237 * or the expire finishes.
238 */
239
240 while (ino->flags & AUTOFS_INF_EXPIRING) {
241 mutex_unlock(&sbi->wq_mutex);
242 schedule_timeout_interruptible(HZ/10);
243 if (mutex_lock_interruptible(&sbi->wq_mutex))
244 return -EINTR;
245
246 if (sbi->flags & AUTOFS_SBI_CATATONIC)
247 return -ENOENT;
248
249 wq = autofs_find_wait(sbi, qstr);
250 if (wq) {
251 *wait = wq;
252 return 1;
253 }
254 }
255
256 /*
257 * Not ideal but the status has already gone. Of the two
258 * cases where we wait on NFY_NONE neither depend on the
259 * return status of the wait.
260 */
261 return 0;
262 }
263
264 /*
265 * If we've been asked to trigger a mount and the request
266 * completed while we waited on the mutex ...
267 */
268 if (notify == NFY_MOUNT) {
269 struct dentry *new = NULL;
270 struct path this;
271 int valid = 1;
272
273 /*
274 * If the dentry was successfully mounted while we slept
275 * on the wait queue mutex we can return success. If it
276 * isn't mounted (doesn't have submounts for the case of
277 * a multi-mount with no mount at it's base) we can
278 * continue on and create a new request.
279 */
280 if (!IS_ROOT(dentry)) {
281 if (d_unhashed(dentry) &&
282 d_really_is_positive(dentry)) {
283 struct dentry *parent = dentry->d_parent;
284
285 new = d_lookup(parent, &dentry->d_name);
286 if (new)
287 dentry = new;
288 }
289 }
290 this.mnt = path->mnt;
291 this.dentry = dentry;
292 if (path_has_submounts(&this))
293 valid = 0;
294
295 if (new)
296 dput(new);
297 return valid;
298 }
299
300 return 1;
301}
302
303int autofs_wait(struct autofs_sb_info *sbi,
304 const struct path *path, enum autofs_notify notify)
305{
306 struct dentry *dentry = path->dentry;
307 struct autofs_wait_queue *wq;
308 struct qstr qstr;
309 char *name;
310 int status, ret, type;
311 unsigned int offset = 0;
312 pid_t pid;
313 pid_t tgid;
314
315 /* In catatonic mode, we don't wait for nobody */
316 if (sbi->flags & AUTOFS_SBI_CATATONIC)
317 return -ENOENT;
318
319 /*
320 * Try translating pids to the namespace of the daemon.
321 *
322 * Zero means failure: we are in an unrelated pid namespace.
323 */
324 pid = task_pid_nr_ns(current, ns_of_pid(sbi->oz_pgrp));
325 tgid = task_tgid_nr_ns(current, ns_of_pid(sbi->oz_pgrp));
326 if (pid == 0 || tgid == 0)
327 return -ENOENT;
328
329 if (d_really_is_negative(dentry)) {
330 /*
331 * A wait for a negative dentry is invalid for certain
332 * cases. A direct or offset mount "always" has its mount
333 * point directory created and so the request dentry must
334 * be positive or the map key doesn't exist. The situation
335 * is very similar for indirect mounts except only dentrys
336 * in the root of the autofs file system may be negative.
337 */
338 if (autofs_type_trigger(sbi->type))
339 return -ENOENT;
340 else if (!IS_ROOT(dentry->d_parent))
341 return -ENOENT;
342 }
343
344 name = kmalloc(NAME_MAX + 1, GFP_KERNEL);
345 if (!name)
346 return -ENOMEM;
347
348 /* If this is a direct mount request create a dummy name */
349 if (IS_ROOT(dentry) && autofs_type_trigger(sbi->type)) {
350 qstr.name = name;
351 qstr.len = sprintf(name, "%p", dentry);
352 } else {
353 char *p = dentry_path_raw(dentry, name, NAME_MAX);
354 if (IS_ERR(p)) {
355 kfree(name);
356 return -ENOENT;
357 }
358 qstr.name = ++p; // skip the leading slash
359 qstr.len = strlen(p);
360 offset = p - name;
361 }
362 qstr.hash = full_name_hash(dentry, qstr.name, qstr.len);
363
364 if (mutex_lock_interruptible(&sbi->wq_mutex)) {
365 kfree(name);
366 return -EINTR;
367 }
368
369 ret = validate_request(&wq, sbi, &qstr, path, notify);
370 if (ret <= 0) {
371 if (ret != -EINTR)
372 mutex_unlock(&sbi->wq_mutex);
373 kfree(name);
374 return ret;
375 }
376
377 if (!wq) {
378 /* Create a new wait queue */
379 wq = kmalloc(sizeof(struct autofs_wait_queue), GFP_KERNEL);
380 if (!wq) {
381 kfree(name);
382 mutex_unlock(&sbi->wq_mutex);
383 return -ENOMEM;
384 }
385
386 wq->wait_queue_token = autofs_next_wait_queue;
387 if (++autofs_next_wait_queue == 0)
388 autofs_next_wait_queue = 1;
389 wq->next = sbi->queues;
390 sbi->queues = wq;
391 init_waitqueue_head(&wq->queue);
392 memcpy(&wq->name, &qstr, sizeof(struct qstr));
393 wq->offset = offset;
394 wq->dev = autofs_get_dev(sbi);
395 wq->ino = autofs_get_ino(sbi);
396 wq->uid = current_uid();
397 wq->gid = current_gid();
398 wq->pid = pid;
399 wq->tgid = tgid;
400 wq->status = -EINTR; /* Status return if interrupted */
401 wq->wait_ctr = 2;
402
403 if (sbi->version < 5) {
404 if (notify == NFY_MOUNT)
405 type = autofs_ptype_missing;
406 else
407 type = autofs_ptype_expire_multi;
408 } else {
409 if (notify == NFY_MOUNT)
410 type = autofs_type_trigger(sbi->type) ?
411 autofs_ptype_missing_direct :
412 autofs_ptype_missing_indirect;
413 else
414 type = autofs_type_trigger(sbi->type) ?
415 autofs_ptype_expire_direct :
416 autofs_ptype_expire_indirect;
417 }
418
419 pr_debug("new wait id = 0x%08lx, name = %.*s, nfy=%d\n",
420 (unsigned long) wq->wait_queue_token, wq->name.len,
421 wq->name.name, notify);
422
423 /*
424 * autofs_notify_daemon() may block; it will unlock ->wq_mutex
425 */
426 autofs_notify_daemon(sbi, wq, type);
427 } else {
428 wq->wait_ctr++;
429 pr_debug("existing wait id = 0x%08lx, name = %.*s, nfy=%d\n",
430 (unsigned long) wq->wait_queue_token, wq->name.len,
431 wq->name.name, notify);
432 mutex_unlock(&sbi->wq_mutex);
433 kfree(name);
434 }
435
436 /*
437 * wq->name.name is NULL iff the lock is already released
438 * or the mount has been made catatonic.
439 */
440 wait_event_killable(wq->queue, wq->name.name == NULL);
441 status = wq->status;
442
443 /*
444 * For direct and offset mounts we need to track the requester's
445 * uid and gid in the dentry info struct. This is so it can be
446 * supplied, on request, by the misc device ioctl interface.
447 * This is needed during daemon resatart when reconnecting
448 * to existing, active, autofs mounts. The uid and gid (and
449 * related string values) may be used for macro substitution
450 * in autofs mount maps.
451 */
452 if (!status) {
453 struct autofs_info *ino;
454 struct dentry *de = NULL;
455
456 /* direct mount or browsable map */
457 ino = autofs_dentry_ino(dentry);
458 if (!ino) {
459 /* If not lookup actual dentry used */
460 de = d_lookup(dentry->d_parent, &dentry->d_name);
461 if (de)
462 ino = autofs_dentry_ino(de);
463 }
464
465 /* Set mount requester */
466 if (ino) {
467 spin_lock(&sbi->fs_lock);
468 ino->uid = wq->uid;
469 ino->gid = wq->gid;
470 spin_unlock(&sbi->fs_lock);
471 }
472
473 if (de)
474 dput(de);
475 }
476
477 /* Are we the last process to need status? */
478 mutex_lock(&sbi->wq_mutex);
479 if (!--wq->wait_ctr)
480 kfree(wq);
481 mutex_unlock(&sbi->wq_mutex);
482
483 return status;
484}
485
486
487int autofs_wait_release(struct autofs_sb_info *sbi,
488 autofs_wqt_t wait_queue_token, int status)
489{
490 struct autofs_wait_queue *wq, **wql;
491
492 mutex_lock(&sbi->wq_mutex);
493 for (wql = &sbi->queues; (wq = *wql) != NULL; wql = &wq->next) {
494 if (wq->wait_queue_token == wait_queue_token)
495 break;
496 }
497
498 if (!wq) {
499 mutex_unlock(&sbi->wq_mutex);
500 return -EINVAL;
501 }
502
503 *wql = wq->next; /* Unlink from chain */
504 kfree(wq->name.name - wq->offset);
505 wq->name.name = NULL; /* Do not wait on this queue */
506 wq->status = status;
507 wake_up(&wq->queue);
508 if (!--wq->wait_ctr)
509 kfree(wq);
510 mutex_unlock(&sbi->wq_mutex);
511
512 return 0;
513}
1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
4 * Copyright 2001-2006 Ian Kent <raven@themaw.net>
5 */
6
7#include <linux/sched/signal.h>
8#include "autofs_i.h"
9
10/* We make this a static variable rather than a part of the superblock; it
11 * is better if we don't reassign numbers easily even across filesystems
12 */
13static autofs_wqt_t autofs_next_wait_queue = 1;
14
15void autofs_catatonic_mode(struct autofs_sb_info *sbi)
16{
17 struct autofs_wait_queue *wq, *nwq;
18
19 mutex_lock(&sbi->wq_mutex);
20 if (sbi->flags & AUTOFS_SBI_CATATONIC) {
21 mutex_unlock(&sbi->wq_mutex);
22 return;
23 }
24
25 pr_debug("entering catatonic mode\n");
26
27 sbi->flags |= AUTOFS_SBI_CATATONIC;
28 wq = sbi->queues;
29 sbi->queues = NULL; /* Erase all wait queues */
30 while (wq) {
31 nwq = wq->next;
32 wq->status = -ENOENT; /* Magic is gone - report failure */
33 kfree(wq->name.name);
34 wq->name.name = NULL;
35 wq->wait_ctr--;
36 wake_up_interruptible(&wq->queue);
37 wq = nwq;
38 }
39 fput(sbi->pipe); /* Close the pipe */
40 sbi->pipe = NULL;
41 sbi->pipefd = -1;
42 mutex_unlock(&sbi->wq_mutex);
43}
44
45static int autofs_write(struct autofs_sb_info *sbi,
46 struct file *file, const void *addr, int bytes)
47{
48 unsigned long sigpipe, flags;
49 const char *data = (const char *)addr;
50 ssize_t wr = 0;
51
52 sigpipe = sigismember(¤t->pending.signal, SIGPIPE);
53
54 mutex_lock(&sbi->pipe_mutex);
55 while (bytes) {
56 wr = __kernel_write(file, data, bytes, NULL);
57 if (wr <= 0)
58 break;
59 data += wr;
60 bytes -= wr;
61 }
62 mutex_unlock(&sbi->pipe_mutex);
63
64 /* Keep the currently executing process from receiving a
65 * SIGPIPE unless it was already supposed to get one
66 */
67 if (wr == -EPIPE && !sigpipe) {
68 spin_lock_irqsave(¤t->sighand->siglock, flags);
69 sigdelset(¤t->pending.signal, SIGPIPE);
70 recalc_sigpending();
71 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
72 }
73
74 /* if 'wr' returned 0 (impossible) we assume -EIO (safe) */
75 return bytes == 0 ? 0 : wr < 0 ? wr : -EIO;
76}
77
78static void autofs_notify_daemon(struct autofs_sb_info *sbi,
79 struct autofs_wait_queue *wq,
80 int type)
81{
82 union {
83 struct autofs_packet_hdr hdr;
84 union autofs_packet_union v4_pkt;
85 union autofs_v5_packet_union v5_pkt;
86 } pkt;
87 struct file *pipe = NULL;
88 size_t pktsz;
89 int ret;
90
91 pr_debug("wait id = 0x%08lx, name = %.*s, type=%d\n",
92 (unsigned long) wq->wait_queue_token,
93 wq->name.len, wq->name.name, type);
94
95 memset(&pkt, 0, sizeof(pkt)); /* For security reasons */
96
97 pkt.hdr.proto_version = sbi->version;
98 pkt.hdr.type = type;
99
100 switch (type) {
101 /* Kernel protocol v4 missing and expire packets */
102 case autofs_ptype_missing:
103 {
104 struct autofs_packet_missing *mp = &pkt.v4_pkt.missing;
105
106 pktsz = sizeof(*mp);
107
108 mp->wait_queue_token = wq->wait_queue_token;
109 mp->len = wq->name.len;
110 memcpy(mp->name, wq->name.name, wq->name.len);
111 mp->name[wq->name.len] = '\0';
112 break;
113 }
114 case autofs_ptype_expire_multi:
115 {
116 struct autofs_packet_expire_multi *ep =
117 &pkt.v4_pkt.expire_multi;
118
119 pktsz = sizeof(*ep);
120
121 ep->wait_queue_token = wq->wait_queue_token;
122 ep->len = wq->name.len;
123 memcpy(ep->name, wq->name.name, wq->name.len);
124 ep->name[wq->name.len] = '\0';
125 break;
126 }
127 /*
128 * Kernel protocol v5 packet for handling indirect and direct
129 * mount missing and expire requests
130 */
131 case autofs_ptype_missing_indirect:
132 case autofs_ptype_expire_indirect:
133 case autofs_ptype_missing_direct:
134 case autofs_ptype_expire_direct:
135 {
136 struct autofs_v5_packet *packet = &pkt.v5_pkt.v5_packet;
137 struct user_namespace *user_ns = sbi->pipe->f_cred->user_ns;
138
139 pktsz = sizeof(*packet);
140
141 packet->wait_queue_token = wq->wait_queue_token;
142 packet->len = wq->name.len;
143 memcpy(packet->name, wq->name.name, wq->name.len);
144 packet->name[wq->name.len] = '\0';
145 packet->dev = wq->dev;
146 packet->ino = wq->ino;
147 packet->uid = from_kuid_munged(user_ns, wq->uid);
148 packet->gid = from_kgid_munged(user_ns, wq->gid);
149 packet->pid = wq->pid;
150 packet->tgid = wq->tgid;
151 break;
152 }
153 default:
154 pr_warn("bad type %d!\n", type);
155 mutex_unlock(&sbi->wq_mutex);
156 return;
157 }
158
159 pipe = get_file(sbi->pipe);
160
161 mutex_unlock(&sbi->wq_mutex);
162
163 switch (ret = autofs_write(sbi, pipe, &pkt, pktsz)) {
164 case 0:
165 break;
166 case -ENOMEM:
167 case -ERESTARTSYS:
168 /* Just fail this one */
169 autofs_wait_release(sbi, wq->wait_queue_token, ret);
170 break;
171 default:
172 autofs_catatonic_mode(sbi);
173 break;
174 }
175 fput(pipe);
176}
177
178static int autofs_getpath(struct autofs_sb_info *sbi,
179 struct dentry *dentry, char *name)
180{
181 struct dentry *root = sbi->sb->s_root;
182 struct dentry *tmp;
183 char *buf;
184 char *p;
185 int len;
186 unsigned seq;
187
188rename_retry:
189 buf = name;
190 len = 0;
191
192 seq = read_seqbegin(&rename_lock);
193 rcu_read_lock();
194 spin_lock(&sbi->fs_lock);
195 for (tmp = dentry ; tmp != root ; tmp = tmp->d_parent)
196 len += tmp->d_name.len + 1;
197
198 if (!len || --len > NAME_MAX) {
199 spin_unlock(&sbi->fs_lock);
200 rcu_read_unlock();
201 if (read_seqretry(&rename_lock, seq))
202 goto rename_retry;
203 return 0;
204 }
205
206 *(buf + len) = '\0';
207 p = buf + len - dentry->d_name.len;
208 strncpy(p, dentry->d_name.name, dentry->d_name.len);
209
210 for (tmp = dentry->d_parent; tmp != root ; tmp = tmp->d_parent) {
211 *(--p) = '/';
212 p -= tmp->d_name.len;
213 strncpy(p, tmp->d_name.name, tmp->d_name.len);
214 }
215 spin_unlock(&sbi->fs_lock);
216 rcu_read_unlock();
217 if (read_seqretry(&rename_lock, seq))
218 goto rename_retry;
219
220 return len;
221}
222
223static struct autofs_wait_queue *
224autofs_find_wait(struct autofs_sb_info *sbi, const struct qstr *qstr)
225{
226 struct autofs_wait_queue *wq;
227
228 for (wq = sbi->queues; wq; wq = wq->next) {
229 if (wq->name.hash == qstr->hash &&
230 wq->name.len == qstr->len &&
231 wq->name.name &&
232 !memcmp(wq->name.name, qstr->name, qstr->len))
233 break;
234 }
235 return wq;
236}
237
238/*
239 * Check if we have a valid request.
240 * Returns
241 * 1 if the request should continue.
242 * In this case we can return an autofs_wait_queue entry if one is
243 * found or NULL to idicate a new wait needs to be created.
244 * 0 or a negative errno if the request shouldn't continue.
245 */
246static int validate_request(struct autofs_wait_queue **wait,
247 struct autofs_sb_info *sbi,
248 const struct qstr *qstr,
249 const struct path *path, enum autofs_notify notify)
250{
251 struct dentry *dentry = path->dentry;
252 struct autofs_wait_queue *wq;
253 struct autofs_info *ino;
254
255 if (sbi->flags & AUTOFS_SBI_CATATONIC)
256 return -ENOENT;
257
258 /* Wait in progress, continue; */
259 wq = autofs_find_wait(sbi, qstr);
260 if (wq) {
261 *wait = wq;
262 return 1;
263 }
264
265 *wait = NULL;
266
267 /* If we don't yet have any info this is a new request */
268 ino = autofs_dentry_ino(dentry);
269 if (!ino)
270 return 1;
271
272 /*
273 * If we've been asked to wait on an existing expire (NFY_NONE)
274 * but there is no wait in the queue ...
275 */
276 if (notify == NFY_NONE) {
277 /*
278 * Either we've betean the pending expire to post it's
279 * wait or it finished while we waited on the mutex.
280 * So we need to wait till either, the wait appears
281 * or the expire finishes.
282 */
283
284 while (ino->flags & AUTOFS_INF_EXPIRING) {
285 mutex_unlock(&sbi->wq_mutex);
286 schedule_timeout_interruptible(HZ/10);
287 if (mutex_lock_interruptible(&sbi->wq_mutex))
288 return -EINTR;
289
290 if (sbi->flags & AUTOFS_SBI_CATATONIC)
291 return -ENOENT;
292
293 wq = autofs_find_wait(sbi, qstr);
294 if (wq) {
295 *wait = wq;
296 return 1;
297 }
298 }
299
300 /*
301 * Not ideal but the status has already gone. Of the two
302 * cases where we wait on NFY_NONE neither depend on the
303 * return status of the wait.
304 */
305 return 0;
306 }
307
308 /*
309 * If we've been asked to trigger a mount and the request
310 * completed while we waited on the mutex ...
311 */
312 if (notify == NFY_MOUNT) {
313 struct dentry *new = NULL;
314 struct path this;
315 int valid = 1;
316
317 /*
318 * If the dentry was successfully mounted while we slept
319 * on the wait queue mutex we can return success. If it
320 * isn't mounted (doesn't have submounts for the case of
321 * a multi-mount with no mount at it's base) we can
322 * continue on and create a new request.
323 */
324 if (!IS_ROOT(dentry)) {
325 if (d_unhashed(dentry) &&
326 d_really_is_positive(dentry)) {
327 struct dentry *parent = dentry->d_parent;
328
329 new = d_lookup(parent, &dentry->d_name);
330 if (new)
331 dentry = new;
332 }
333 }
334 this.mnt = path->mnt;
335 this.dentry = dentry;
336 if (path_has_submounts(&this))
337 valid = 0;
338
339 if (new)
340 dput(new);
341 return valid;
342 }
343
344 return 1;
345}
346
347int autofs_wait(struct autofs_sb_info *sbi,
348 const struct path *path, enum autofs_notify notify)
349{
350 struct dentry *dentry = path->dentry;
351 struct autofs_wait_queue *wq;
352 struct qstr qstr;
353 char *name;
354 int status, ret, type;
355 pid_t pid;
356 pid_t tgid;
357
358 /* In catatonic mode, we don't wait for nobody */
359 if (sbi->flags & AUTOFS_SBI_CATATONIC)
360 return -ENOENT;
361
362 /*
363 * Try translating pids to the namespace of the daemon.
364 *
365 * Zero means failure: we are in an unrelated pid namespace.
366 */
367 pid = task_pid_nr_ns(current, ns_of_pid(sbi->oz_pgrp));
368 tgid = task_tgid_nr_ns(current, ns_of_pid(sbi->oz_pgrp));
369 if (pid == 0 || tgid == 0)
370 return -ENOENT;
371
372 if (d_really_is_negative(dentry)) {
373 /*
374 * A wait for a negative dentry is invalid for certain
375 * cases. A direct or offset mount "always" has its mount
376 * point directory created and so the request dentry must
377 * be positive or the map key doesn't exist. The situation
378 * is very similar for indirect mounts except only dentrys
379 * in the root of the autofs file system may be negative.
380 */
381 if (autofs_type_trigger(sbi->type))
382 return -ENOENT;
383 else if (!IS_ROOT(dentry->d_parent))
384 return -ENOENT;
385 }
386
387 name = kmalloc(NAME_MAX + 1, GFP_KERNEL);
388 if (!name)
389 return -ENOMEM;
390
391 /* If this is a direct mount request create a dummy name */
392 if (IS_ROOT(dentry) && autofs_type_trigger(sbi->type))
393 qstr.len = sprintf(name, "%p", dentry);
394 else {
395 qstr.len = autofs_getpath(sbi, dentry, name);
396 if (!qstr.len) {
397 kfree(name);
398 return -ENOENT;
399 }
400 }
401 qstr.name = name;
402 qstr.hash = full_name_hash(dentry, name, qstr.len);
403
404 if (mutex_lock_interruptible(&sbi->wq_mutex)) {
405 kfree(qstr.name);
406 return -EINTR;
407 }
408
409 ret = validate_request(&wq, sbi, &qstr, path, notify);
410 if (ret <= 0) {
411 if (ret != -EINTR)
412 mutex_unlock(&sbi->wq_mutex);
413 kfree(qstr.name);
414 return ret;
415 }
416
417 if (!wq) {
418 /* Create a new wait queue */
419 wq = kmalloc(sizeof(struct autofs_wait_queue), GFP_KERNEL);
420 if (!wq) {
421 kfree(qstr.name);
422 mutex_unlock(&sbi->wq_mutex);
423 return -ENOMEM;
424 }
425
426 wq->wait_queue_token = autofs_next_wait_queue;
427 if (++autofs_next_wait_queue == 0)
428 autofs_next_wait_queue = 1;
429 wq->next = sbi->queues;
430 sbi->queues = wq;
431 init_waitqueue_head(&wq->queue);
432 memcpy(&wq->name, &qstr, sizeof(struct qstr));
433 wq->dev = autofs_get_dev(sbi);
434 wq->ino = autofs_get_ino(sbi);
435 wq->uid = current_uid();
436 wq->gid = current_gid();
437 wq->pid = pid;
438 wq->tgid = tgid;
439 wq->status = -EINTR; /* Status return if interrupted */
440 wq->wait_ctr = 2;
441
442 if (sbi->version < 5) {
443 if (notify == NFY_MOUNT)
444 type = autofs_ptype_missing;
445 else
446 type = autofs_ptype_expire_multi;
447 } else {
448 if (notify == NFY_MOUNT)
449 type = autofs_type_trigger(sbi->type) ?
450 autofs_ptype_missing_direct :
451 autofs_ptype_missing_indirect;
452 else
453 type = autofs_type_trigger(sbi->type) ?
454 autofs_ptype_expire_direct :
455 autofs_ptype_expire_indirect;
456 }
457
458 pr_debug("new wait id = 0x%08lx, name = %.*s, nfy=%d\n",
459 (unsigned long) wq->wait_queue_token, wq->name.len,
460 wq->name.name, notify);
461
462 /*
463 * autofs_notify_daemon() may block; it will unlock ->wq_mutex
464 */
465 autofs_notify_daemon(sbi, wq, type);
466 } else {
467 wq->wait_ctr++;
468 pr_debug("existing wait id = 0x%08lx, name = %.*s, nfy=%d\n",
469 (unsigned long) wq->wait_queue_token, wq->name.len,
470 wq->name.name, notify);
471 mutex_unlock(&sbi->wq_mutex);
472 kfree(qstr.name);
473 }
474
475 /*
476 * wq->name.name is NULL iff the lock is already released
477 * or the mount has been made catatonic.
478 */
479 wait_event_killable(wq->queue, wq->name.name == NULL);
480 status = wq->status;
481
482 /*
483 * For direct and offset mounts we need to track the requester's
484 * uid and gid in the dentry info struct. This is so it can be
485 * supplied, on request, by the misc device ioctl interface.
486 * This is needed during daemon resatart when reconnecting
487 * to existing, active, autofs mounts. The uid and gid (and
488 * related string values) may be used for macro substitution
489 * in autofs mount maps.
490 */
491 if (!status) {
492 struct autofs_info *ino;
493 struct dentry *de = NULL;
494
495 /* direct mount or browsable map */
496 ino = autofs_dentry_ino(dentry);
497 if (!ino) {
498 /* If not lookup actual dentry used */
499 de = d_lookup(dentry->d_parent, &dentry->d_name);
500 if (de)
501 ino = autofs_dentry_ino(de);
502 }
503
504 /* Set mount requester */
505 if (ino) {
506 spin_lock(&sbi->fs_lock);
507 ino->uid = wq->uid;
508 ino->gid = wq->gid;
509 spin_unlock(&sbi->fs_lock);
510 }
511
512 if (de)
513 dput(de);
514 }
515
516 /* Are we the last process to need status? */
517 mutex_lock(&sbi->wq_mutex);
518 if (!--wq->wait_ctr)
519 kfree(wq);
520 mutex_unlock(&sbi->wq_mutex);
521
522 return status;
523}
524
525
526int autofs_wait_release(struct autofs_sb_info *sbi,
527 autofs_wqt_t wait_queue_token, int status)
528{
529 struct autofs_wait_queue *wq, **wql;
530
531 mutex_lock(&sbi->wq_mutex);
532 for (wql = &sbi->queues; (wq = *wql) != NULL; wql = &wq->next) {
533 if (wq->wait_queue_token == wait_queue_token)
534 break;
535 }
536
537 if (!wq) {
538 mutex_unlock(&sbi->wq_mutex);
539 return -EINVAL;
540 }
541
542 *wql = wq->next; /* Unlink from chain */
543 kfree(wq->name.name);
544 wq->name.name = NULL; /* Do not wait on this queue */
545 wq->status = status;
546 wake_up(&wq->queue);
547 if (!--wq->wait_ctr)
548 kfree(wq);
549 mutex_unlock(&sbi->wq_mutex);
550
551 return 0;
552}