1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * Copyright 1997-1998 Transmeta Corporation -- All Rights Reserved
4 * Copyright 2001-2006 Ian Kent <raven@themaw.net>
7 #include <linux/sched/signal.h>
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
13 static autofs_wqt_t autofs_next_wait_queue = 1;
15 void autofs_catatonic_mode(struct autofs_sb_info *sbi)
17 struct autofs_wait_queue *wq, *nwq;
19 mutex_lock(&sbi->wq_mutex);
20 if (sbi->flags & AUTOFS_SBI_CATATONIC) {
21 mutex_unlock(&sbi->wq_mutex);
25 pr_debug("entering catatonic mode\n");
27 sbi->flags |= AUTOFS_SBI_CATATONIC;
29 sbi->queues = NULL; /* Erase all wait queues */
32 wq->status = -ENOENT; /* Magic is gone - report failure */
35 wake_up_interruptible(&wq->queue);
40 fput(sbi->pipe); /* Close the pipe */
43 mutex_unlock(&sbi->wq_mutex);
46 static int autofs_write(struct autofs_sb_info *sbi,
47 struct file *file, const void *addr, int bytes)
49 unsigned long sigpipe, flags;
50 const char *data = (const char *)addr;
53 sigpipe = sigismember(¤t->pending.signal, SIGPIPE);
55 mutex_lock(&sbi->pipe_mutex);
57 wr = __kernel_write(file, data, bytes, NULL);
63 mutex_unlock(&sbi->pipe_mutex);
65 /* Keep the currently executing process from receiving a
66 * SIGPIPE unless it was already supposed to get one
68 if (wr == -EPIPE && !sigpipe) {
69 spin_lock_irqsave(¤t->sighand->siglock, flags);
70 sigdelset(¤t->pending.signal, SIGPIPE);
72 spin_unlock_irqrestore(¤t->sighand->siglock, flags);
75 /* if 'wr' returned 0 (impossible) we assume -EIO (safe) */
76 return bytes == 0 ? 0 : wr < 0 ? wr : -EIO;
79 static void autofs_notify_daemon(struct autofs_sb_info *sbi,
80 struct autofs_wait_queue *wq,
84 struct autofs_packet_hdr hdr;
85 union autofs_packet_union v4_pkt;
86 union autofs_v5_packet_union v5_pkt;
88 struct file *pipe = NULL;
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);
96 memset(&pkt, 0, sizeof(pkt)); /* For security reasons */
98 pkt.hdr.proto_version = sbi->version;
102 /* Kernel protocol v4 missing and expire packets */
103 case autofs_ptype_missing:
105 struct autofs_packet_missing *mp = &pkt.v4_pkt.missing;
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';
115 case autofs_ptype_expire_multi:
117 struct autofs_packet_expire_multi *ep =
118 &pkt.v4_pkt.expire_multi;
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';
129 * Kernel protocol v5 packet for handling indirect and direct
130 * mount missing and expire requests
132 case autofs_ptype_missing_indirect:
133 case autofs_ptype_expire_indirect:
134 case autofs_ptype_missing_direct:
135 case autofs_ptype_expire_direct:
137 struct autofs_v5_packet *packet = &pkt.v5_pkt.v5_packet;
138 struct user_namespace *user_ns = sbi->pipe->f_cred->user_ns;
140 pktsz = sizeof(*packet);
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;
155 pr_warn("bad type %d!\n", type);
156 mutex_unlock(&sbi->wq_mutex);
160 pipe = get_file(sbi->pipe);
162 mutex_unlock(&sbi->wq_mutex);
164 switch (ret = autofs_write(sbi, pipe, &pkt, pktsz)) {
169 /* Just fail this one */
170 autofs_wait_release(sbi, wq->wait_queue_token, ret);
173 autofs_catatonic_mode(sbi);
179 static int autofs_getpath(struct autofs_sb_info *sbi,
180 struct dentry *dentry, char *name)
182 struct dentry *root = sbi->sb->s_root;
193 seq = read_seqbegin(&rename_lock);
195 spin_lock(&sbi->fs_lock);
196 for (tmp = dentry ; tmp != root ; tmp = tmp->d_parent)
197 len += tmp->d_name.len + 1;
199 if (!len || --len > NAME_MAX) {
200 spin_unlock(&sbi->fs_lock);
202 if (read_seqretry(&rename_lock, seq))
208 p = buf + len - dentry->d_name.len;
209 strncpy(p, dentry->d_name.name, dentry->d_name.len);
211 for (tmp = dentry->d_parent; tmp != root ; tmp = tmp->d_parent) {
213 p -= tmp->d_name.len;
214 strncpy(p, tmp->d_name.name, tmp->d_name.len);
216 spin_unlock(&sbi->fs_lock);
218 if (read_seqretry(&rename_lock, seq))
224 static struct autofs_wait_queue *
225 autofs_find_wait(struct autofs_sb_info *sbi, const struct qstr *qstr)
227 struct autofs_wait_queue *wq;
229 for (wq = sbi->queues; wq; wq = wq->next) {
230 if (wq->name.hash == qstr->hash &&
231 wq->name.len == qstr->len &&
233 !memcmp(wq->name.name, qstr->name, qstr->len))
240 * Check if we have a valid request.
242 * 1 if the request should continue.
243 * In this case we can return an autofs_wait_queue entry if one is
244 * found or NULL to idicate a new wait needs to be created.
245 * 0 or a negative errno if the request shouldn't continue.
247 static int validate_request(struct autofs_wait_queue **wait,
248 struct autofs_sb_info *sbi,
249 const struct qstr *qstr,
250 const struct path *path, enum autofs_notify notify)
252 struct dentry *dentry = path->dentry;
253 struct autofs_wait_queue *wq;
254 struct autofs_info *ino;
256 if (sbi->flags & AUTOFS_SBI_CATATONIC)
259 /* Wait in progress, continue; */
260 wq = autofs_find_wait(sbi, qstr);
268 /* If we don't yet have any info this is a new request */
269 ino = autofs_dentry_ino(dentry);
274 * If we've been asked to wait on an existing expire (NFY_NONE)
275 * but there is no wait in the queue ...
277 if (notify == NFY_NONE) {
279 * Either we've betean the pending expire to post it's
280 * wait or it finished while we waited on the mutex.
281 * So we need to wait till either, the wait appears
282 * or the expire finishes.
285 while (ino->flags & AUTOFS_INF_EXPIRING) {
286 mutex_unlock(&sbi->wq_mutex);
287 schedule_timeout_interruptible(HZ/10);
288 if (mutex_lock_interruptible(&sbi->wq_mutex))
291 if (sbi->flags & AUTOFS_SBI_CATATONIC)
294 wq = autofs_find_wait(sbi, qstr);
302 * Not ideal but the status has already gone. Of the two
303 * cases where we wait on NFY_NONE neither depend on the
304 * return status of the wait.
310 * If we've been asked to trigger a mount and the request
311 * completed while we waited on the mutex ...
313 if (notify == NFY_MOUNT) {
314 struct dentry *new = NULL;
319 * If the dentry was successfully mounted while we slept
320 * on the wait queue mutex we can return success. If it
321 * isn't mounted (doesn't have submounts for the case of
322 * a multi-mount with no mount at it's base) we can
323 * continue on and create a new request.
325 if (!IS_ROOT(dentry)) {
326 if (d_unhashed(dentry) &&
327 d_really_is_positive(dentry)) {
328 struct dentry *parent = dentry->d_parent;
330 new = d_lookup(parent, &dentry->d_name);
335 this.mnt = path->mnt;
336 this.dentry = dentry;
337 if (path_has_submounts(&this))
348 int autofs_wait(struct autofs_sb_info *sbi,
349 const struct path *path, enum autofs_notify notify)
351 struct dentry *dentry = path->dentry;
352 struct autofs_wait_queue *wq;
355 int status, ret, type;
359 /* In catatonic mode, we don't wait for nobody */
360 if (sbi->flags & AUTOFS_SBI_CATATONIC)
364 * Try translating pids to the namespace of the daemon.
366 * Zero means failure: we are in an unrelated pid namespace.
368 pid = task_pid_nr_ns(current, ns_of_pid(sbi->oz_pgrp));
369 tgid = task_tgid_nr_ns(current, ns_of_pid(sbi->oz_pgrp));
370 if (pid == 0 || tgid == 0)
373 if (d_really_is_negative(dentry)) {
375 * A wait for a negative dentry is invalid for certain
376 * cases. A direct or offset mount "always" has its mount
377 * point directory created and so the request dentry must
378 * be positive or the map key doesn't exist. The situation
379 * is very similar for indirect mounts except only dentrys
380 * in the root of the autofs file system may be negative.
382 if (autofs_type_trigger(sbi->type))
384 else if (!IS_ROOT(dentry->d_parent))
388 name = kmalloc(NAME_MAX + 1, GFP_KERNEL);
392 /* If this is a direct mount request create a dummy name */
393 if (IS_ROOT(dentry) && autofs_type_trigger(sbi->type))
394 qstr.len = sprintf(name, "%p", dentry);
396 qstr.len = autofs_getpath(sbi, dentry, name);
403 qstr.hash = full_name_hash(dentry, name, qstr.len);
405 if (mutex_lock_interruptible(&sbi->wq_mutex)) {
410 ret = validate_request(&wq, sbi, &qstr, path, notify);
413 mutex_unlock(&sbi->wq_mutex);
419 /* Create a new wait queue */
420 wq = kmalloc(sizeof(struct autofs_wait_queue), GFP_KERNEL);
423 mutex_unlock(&sbi->wq_mutex);
427 wq->wait_queue_token = autofs_next_wait_queue;
428 if (++autofs_next_wait_queue == 0)
429 autofs_next_wait_queue = 1;
430 wq->next = sbi->queues;
432 init_waitqueue_head(&wq->queue);
433 memcpy(&wq->name, &qstr, sizeof(struct qstr));
434 wq->dev = autofs_get_dev(sbi);
435 wq->ino = autofs_get_ino(sbi);
436 wq->uid = current_uid();
437 wq->gid = current_gid();
440 wq->status = -EINTR; /* Status return if interrupted */
443 if (sbi->version < 5) {
444 if (notify == NFY_MOUNT)
445 type = autofs_ptype_missing;
447 type = autofs_ptype_expire_multi;
449 if (notify == NFY_MOUNT)
450 type = autofs_type_trigger(sbi->type) ?
451 autofs_ptype_missing_direct :
452 autofs_ptype_missing_indirect;
454 type = autofs_type_trigger(sbi->type) ?
455 autofs_ptype_expire_direct :
456 autofs_ptype_expire_indirect;
459 pr_debug("new wait id = 0x%08lx, name = %.*s, nfy=%d\n",
460 (unsigned long) wq->wait_queue_token, wq->name.len,
461 wq->name.name, notify);
464 * autofs_notify_daemon() may block; it will unlock ->wq_mutex
466 autofs_notify_daemon(sbi, wq, type);
469 pr_debug("existing 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 mutex_unlock(&sbi->wq_mutex);
477 * wq->name.name is NULL iff the lock is already released
478 * or the mount has been made catatonic.
480 wait_event_killable(wq->queue, wq->name.name == NULL);
484 * For direct and offset mounts we need to track the requester's
485 * uid and gid in the dentry info struct. This is so it can be
486 * supplied, on request, by the misc device ioctl interface.
487 * This is needed during daemon resatart when reconnecting
488 * to existing, active, autofs mounts. The uid and gid (and
489 * related string values) may be used for macro substitution
490 * in autofs mount maps.
493 struct autofs_info *ino;
494 struct dentry *de = NULL;
496 /* direct mount or browsable map */
497 ino = autofs_dentry_ino(dentry);
499 /* If not lookup actual dentry used */
500 de = d_lookup(dentry->d_parent, &dentry->d_name);
502 ino = autofs_dentry_ino(de);
505 /* Set mount requester */
507 spin_lock(&sbi->fs_lock);
510 spin_unlock(&sbi->fs_lock);
517 /* Are we the last process to need status? */
518 mutex_lock(&sbi->wq_mutex);
521 mutex_unlock(&sbi->wq_mutex);
527 int autofs_wait_release(struct autofs_sb_info *sbi,
528 autofs_wqt_t wait_queue_token, int status)
530 struct autofs_wait_queue *wq, **wql;
532 mutex_lock(&sbi->wq_mutex);
533 for (wql = &sbi->queues; (wq = *wql) != NULL; wql = &wq->next) {
534 if (wq->wait_queue_token == wait_queue_token)
539 mutex_unlock(&sbi->wq_mutex);
543 *wql = wq->next; /* Unlink from chain */
544 kfree(wq->name.name);
545 wq->name.name = NULL; /* Do not wait on this queue */
550 mutex_unlock(&sbi->wq_mutex);