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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 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 struct autofs_wait_queue *
179autofs_find_wait(struct autofs_sb_info *sbi, const struct qstr *qstr)
180{
181 struct autofs_wait_queue *wq;
182
183 for (wq = sbi->queues; wq; wq = wq->next) {
184 if (wq->name.hash == qstr->hash &&
185 wq->name.len == qstr->len &&
186 wq->name.name &&
187 !memcmp(wq->name.name, qstr->name, qstr->len))
188 break;
189 }
190 return wq;
191}
192
193/*
194 * Check if we have a valid request.
195 * Returns
196 * 1 if the request should continue.
197 * In this case we can return an autofs_wait_queue entry if one is
198 * found or NULL to idicate a new wait needs to be created.
199 * 0 or a negative errno if the request shouldn't continue.
200 */
201static int validate_request(struct autofs_wait_queue **wait,
202 struct autofs_sb_info *sbi,
203 const struct qstr *qstr,
204 const struct path *path, enum autofs_notify notify)
205{
206 struct dentry *dentry = path->dentry;
207 struct autofs_wait_queue *wq;
208 struct autofs_info *ino;
209
210 if (sbi->flags & AUTOFS_SBI_CATATONIC)
211 return -ENOENT;
212
213 /* Wait in progress, continue; */
214 wq = autofs_find_wait(sbi, qstr);
215 if (wq) {
216 *wait = wq;
217 return 1;
218 }
219
220 *wait = NULL;
221
222 /* If we don't yet have any info this is a new request */
223 ino = autofs_dentry_ino(dentry);
224 if (!ino)
225 return 1;
226
227 /*
228 * If we've been asked to wait on an existing expire (NFY_NONE)
229 * but there is no wait in the queue ...
230 */
231 if (notify == NFY_NONE) {
232 /*
233 * Either we've betean the pending expire to post it's
234 * wait or it finished while we waited on the mutex.
235 * So we need to wait till either, the wait appears
236 * or the expire finishes.
237 */
238
239 while (ino->flags & AUTOFS_INF_EXPIRING) {
240 mutex_unlock(&sbi->wq_mutex);
241 schedule_timeout_interruptible(HZ/10);
242 if (mutex_lock_interruptible(&sbi->wq_mutex))
243 return -EINTR;
244
245 if (sbi->flags & AUTOFS_SBI_CATATONIC)
246 return -ENOENT;
247
248 wq = autofs_find_wait(sbi, qstr);
249 if (wq) {
250 *wait = wq;
251 return 1;
252 }
253 }
254
255 /*
256 * Not ideal but the status has already gone. Of the two
257 * cases where we wait on NFY_NONE neither depend on the
258 * return status of the wait.
259 */
260 return 0;
261 }
262
263 /*
264 * If we've been asked to trigger a mount and the request
265 * completed while we waited on the mutex ...
266 */
267 if (notify == NFY_MOUNT) {
268 struct dentry *new = NULL;
269 struct path this;
270 int valid = 1;
271
272 /*
273 * If the dentry was successfully mounted while we slept
274 * on the wait queue mutex we can return success. If it
275 * isn't mounted (doesn't have submounts for the case of
276 * a multi-mount with no mount at it's base) we can
277 * continue on and create a new request.
278 */
279 if (!IS_ROOT(dentry)) {
280 if (d_unhashed(dentry) &&
281 d_really_is_positive(dentry)) {
282 struct dentry *parent = dentry->d_parent;
283
284 new = d_lookup(parent, &dentry->d_name);
285 if (new)
286 dentry = new;
287 }
288 }
289 this.mnt = path->mnt;
290 this.dentry = dentry;
291 if (path_has_submounts(&this))
292 valid = 0;
293
294 if (new)
295 dput(new);
296 return valid;
297 }
298
299 return 1;
300}
301
302int autofs_wait(struct autofs_sb_info *sbi,
303 const struct path *path, enum autofs_notify notify)
304{
305 struct dentry *dentry = path->dentry;
306 struct autofs_wait_queue *wq;
307 struct qstr qstr;
308 char *name;
309 int status, ret, type;
310 unsigned int offset = 0;
311 pid_t pid;
312 pid_t tgid;
313
314 /* In catatonic mode, we don't wait for nobody */
315 if (sbi->flags & AUTOFS_SBI_CATATONIC)
316 return -ENOENT;
317
318 /*
319 * Try translating pids to the namespace of the daemon.
320 *
321 * Zero means failure: we are in an unrelated pid namespace.
322 */
323 pid = task_pid_nr_ns(current, ns_of_pid(sbi->oz_pgrp));
324 tgid = task_tgid_nr_ns(current, ns_of_pid(sbi->oz_pgrp));
325 if (pid == 0 || tgid == 0)
326 return -ENOENT;
327
328 if (d_really_is_negative(dentry)) {
329 /*
330 * A wait for a negative dentry is invalid for certain
331 * cases. A direct or offset mount "always" has its mount
332 * point directory created and so the request dentry must
333 * be positive or the map key doesn't exist. The situation
334 * is very similar for indirect mounts except only dentrys
335 * in the root of the autofs file system may be negative.
336 */
337 if (autofs_type_trigger(sbi->type))
338 return -ENOENT;
339 else if (!IS_ROOT(dentry->d_parent))
340 return -ENOENT;
341 }
342
343 name = kmalloc(NAME_MAX + 1, GFP_KERNEL);
344 if (!name)
345 return -ENOMEM;
346
347 /* If this is a direct mount request create a dummy name */
348 if (IS_ROOT(dentry) && autofs_type_trigger(sbi->type)) {
349 qstr.name = name;
350 qstr.len = sprintf(name, "%p", dentry);
351 } else {
352 char *p = dentry_path_raw(dentry, name, NAME_MAX);
353 if (IS_ERR(p)) {
354 kfree(name);
355 return -ENOENT;
356 }
357 qstr.name = ++p; // skip the leading slash
358 qstr.len = strlen(p);
359 offset = p - name;
360 }
361 qstr.hash = full_name_hash(dentry, qstr.name, qstr.len);
362
363 if (mutex_lock_interruptible(&sbi->wq_mutex)) {
364 kfree(name);
365 return -EINTR;
366 }
367
368 ret = validate_request(&wq, sbi, &qstr, path, notify);
369 if (ret <= 0) {
370 if (ret != -EINTR)
371 mutex_unlock(&sbi->wq_mutex);
372 kfree(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(name);
381 mutex_unlock(&sbi->wq_mutex);
382 return -ENOMEM;
383 }
384
385 wq->wait_queue_token = autofs_next_wait_queue;
386 if (++autofs_next_wait_queue == 0)
387 autofs_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->offset = offset;
393 wq->dev = autofs_get_dev(sbi);
394 wq->ino = autofs_get_ino(sbi);
395 wq->uid = current_uid();
396 wq->gid = current_gid();
397 wq->pid = pid;
398 wq->tgid = tgid;
399 wq->status = -EINTR; /* Status return if interrupted */
400 wq->wait_ctr = 2;
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 pr_debug("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 /*
423 * autofs_notify_daemon() may block; it will unlock ->wq_mutex
424 */
425 autofs_notify_daemon(sbi, wq, type);
426 } else {
427 wq->wait_ctr++;
428 pr_debug("existing wait id = 0x%08lx, name = %.*s, nfy=%d\n",
429 (unsigned long) wq->wait_queue_token, wq->name.len,
430 wq->name.name, notify);
431 mutex_unlock(&sbi->wq_mutex);
432 kfree(name);
433 }
434
435 /*
436 * wq->name.name is NULL iff the lock is already released
437 * or the mount has been made catatonic.
438 */
439 wait_event_killable(wq->queue, wq->name.name == NULL);
440 status = wq->status;
441
442 /*
443 * For direct and offset mounts we need to track the requester's
444 * uid and gid in the dentry info struct. This is so it can be
445 * supplied, on request, by the misc device ioctl interface.
446 * This is needed during daemon resatart when reconnecting
447 * to existing, active, autofs mounts. The uid and gid (and
448 * related string values) may be used for macro substitution
449 * in autofs mount maps.
450 */
451 if (!status) {
452 struct autofs_info *ino;
453 struct dentry *de = NULL;
454
455 /* direct mount or browsable map */
456 ino = autofs_dentry_ino(dentry);
457 if (!ino) {
458 /* If not lookup actual dentry used */
459 de = d_lookup(dentry->d_parent, &dentry->d_name);
460 if (de)
461 ino = autofs_dentry_ino(de);
462 }
463
464 /* Set mount requester */
465 if (ino) {
466 spin_lock(&sbi->fs_lock);
467 ino->uid = wq->uid;
468 ino->gid = wq->gid;
469 spin_unlock(&sbi->fs_lock);
470 }
471
472 if (de)
473 dput(de);
474 }
475
476 /* Are we the last process to need status? */
477 mutex_lock(&sbi->wq_mutex);
478 if (!--wq->wait_ctr)
479 kfree(wq);
480 mutex_unlock(&sbi->wq_mutex);
481
482 return status;
483}
484
485
486int autofs_wait_release(struct autofs_sb_info *sbi,
487 autofs_wqt_t wait_queue_token, int status)
488{
489 struct autofs_wait_queue *wq, **wql;
490
491 mutex_lock(&sbi->wq_mutex);
492 for (wql = &sbi->queues; (wq = *wql) != NULL; wql = &wq->next) {
493 if (wq->wait_queue_token == wait_queue_token)
494 break;
495 }
496
497 if (!wq) {
498 mutex_unlock(&sbi->wq_mutex);
499 return -EINVAL;
500 }
501
502 *wql = wq->next; /* Unlink from chain */
503 kfree(wq->name.name - wq->offset);
504 wq->name.name = NULL; /* Do not wait on this queue */
505 wq->status = status;
506 wake_up(&wq->queue);
507 if (!--wq->wait_ctr)
508 kfree(wq);
509 mutex_unlock(&sbi->wq_mutex);
510
511 return 0;
512}