xref: /freebsd/sys/fs/autofs/autofs.c (revision 8ef24a0d4b28fe230e20637f56869cc4148cd2ca)
1 /*-
2  * Copyright (c) 2014 The FreeBSD Foundation
3  * All rights reserved.
4  *
5  * This software was developed by Edward Tomasz Napierala under sponsorship
6  * from the FreeBSD Foundation.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27  * SUCH DAMAGE.
28  *
29  */
30 /*-
31  * Copyright (c) 1989, 1991, 1993, 1995
32  *	The Regents of the University of California.  All rights reserved.
33  *
34  * This code is derived from software contributed to Berkeley by
35  * Rick Macklem at The University of Guelph.
36  *
37  * Redistribution and use in source and binary forms, with or without
38  * modification, are permitted provided that the following conditions
39  * are met:
40  * 1. Redistributions of source code must retain the above copyright
41  *    notice, this list of conditions and the following disclaimer.
42  * 2. Redistributions in binary form must reproduce the above copyright
43  *    notice, this list of conditions and the following disclaimer in the
44  *    documentation and/or other materials provided with the distribution.
45  * 4. Neither the name of the University nor the names of its contributors
46  *    may be used to endorse or promote products derived from this software
47  *    without specific prior written permission.
48  *
49  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
50  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
51  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
52  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
53  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
54  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
55  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
56  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
57  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
58  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
59  * SUCH DAMAGE.
60  *
61  */
62 
63 #include <sys/cdefs.h>
64  __FBSDID("$FreeBSD$");
65 
66 #include <sys/param.h>
67 #include <sys/systm.h>
68 #include <sys/buf.h>
69 #include <sys/conf.h>
70 #include <sys/dirent.h>
71 #include <sys/ioccom.h>
72 #include <sys/kernel.h>
73 #include <sys/module.h>
74 #include <sys/mount.h>
75 #include <sys/refcount.h>
76 #include <sys/sx.h>
77 #include <sys/sysctl.h>
78 #include <sys/syscallsubr.h>
79 #include <sys/taskqueue.h>
80 #include <sys/tree.h>
81 #include <sys/vnode.h>
82 #include <machine/atomic.h>
83 #include <vm/uma.h>
84 
85 #include <fs/autofs/autofs.h>
86 #include <fs/autofs/autofs_ioctl.h>
87 
88 MALLOC_DEFINE(M_AUTOFS, "autofs", "Automounter filesystem");
89 
90 uma_zone_t autofs_request_zone;
91 uma_zone_t autofs_node_zone;
92 
93 static int	autofs_open(struct cdev *dev, int flags, int fmt,
94 		    struct thread *td);
95 static int	autofs_close(struct cdev *dev, int flag, int fmt,
96 		    struct thread *td);
97 static int	autofs_ioctl(struct cdev *dev, u_long cmd, caddr_t arg,
98 		    int mode, struct thread *td);
99 
100 static struct cdevsw autofs_cdevsw = {
101      .d_version = D_VERSION,
102      .d_open   = autofs_open,
103      .d_close   = autofs_close,
104      .d_ioctl   = autofs_ioctl,
105      .d_name    = "autofs",
106 };
107 
108 /*
109  * List of signals that can interrupt an autofs trigger.  Might be a good
110  * idea to keep it synchronised with list in sys/fs/nfs/nfs_commonkrpc.c.
111  */
112 int autofs_sig_set[] = {
113 	SIGINT,
114 	SIGTERM,
115 	SIGHUP,
116 	SIGKILL,
117 	SIGQUIT
118 };
119 
120 struct autofs_softc	*autofs_softc;
121 
122 SYSCTL_NODE(_vfs, OID_AUTO, autofs, CTLFLAG_RD, 0, "Automounter filesystem");
123 int autofs_debug = 1;
124 TUNABLE_INT("vfs.autofs.debug", &autofs_debug);
125 SYSCTL_INT(_vfs_autofs, OID_AUTO, debug, CTLFLAG_RWTUN,
126     &autofs_debug, 1, "Enable debug messages");
127 int autofs_mount_on_stat = 0;
128 TUNABLE_INT("vfs.autofs.mount_on_stat", &autofs_mount_on_stat);
129 SYSCTL_INT(_vfs_autofs, OID_AUTO, mount_on_stat, CTLFLAG_RWTUN,
130     &autofs_mount_on_stat, 0, "Trigger mount on stat(2) on mountpoint");
131 int autofs_timeout = 30;
132 TUNABLE_INT("vfs.autofs.timeout", &autofs_timeout);
133 SYSCTL_INT(_vfs_autofs, OID_AUTO, timeout, CTLFLAG_RWTUN,
134     &autofs_timeout, 30, "Number of seconds to wait for automountd(8)");
135 int autofs_cache = 600;
136 TUNABLE_INT("vfs.autofs.cache", &autofs_cache);
137 SYSCTL_INT(_vfs_autofs, OID_AUTO, cache, CTLFLAG_RWTUN,
138     &autofs_cache, 600, "Number of seconds to wait before reinvoking "
139     "automountd(8) for any given file or directory");
140 int autofs_retry_attempts = 3;
141 TUNABLE_INT("vfs.autofs.retry_attempts", &autofs_retry_attempts);
142 SYSCTL_INT(_vfs_autofs, OID_AUTO, retry_attempts, CTLFLAG_RWTUN,
143     &autofs_retry_attempts, 3, "Number of attempts before failing mount");
144 int autofs_retry_delay = 1;
145 TUNABLE_INT("vfs.autofs.retry_delay", &autofs_retry_delay);
146 SYSCTL_INT(_vfs_autofs, OID_AUTO, retry_delay, CTLFLAG_RWTUN,
147     &autofs_retry_delay, 1, "Number of seconds before retrying");
148 int autofs_interruptible = 1;
149 TUNABLE_INT("vfs.autofs.interruptible", &autofs_interruptible);
150 SYSCTL_INT(_vfs_autofs, OID_AUTO, interruptible, CTLFLAG_RWTUN,
151     &autofs_interruptible, 1, "Allow requests to be interrupted by signal");
152 
153 static int
154 autofs_node_cmp(const struct autofs_node *a, const struct autofs_node *b)
155 {
156 
157 	return (strcmp(a->an_name, b->an_name));
158 }
159 
160 RB_GENERATE(autofs_node_tree, autofs_node, an_link, autofs_node_cmp);
161 
162 int
163 autofs_init(struct vfsconf *vfsp)
164 {
165 	int error;
166 
167 	KASSERT(autofs_softc == NULL,
168 	    ("softc %p, should be NULL", autofs_softc));
169 
170 	autofs_softc = malloc(sizeof(*autofs_softc), M_AUTOFS,
171 	    M_WAITOK | M_ZERO);
172 
173 	autofs_request_zone = uma_zcreate("autofs_request",
174 	    sizeof(struct autofs_request), NULL, NULL, NULL, NULL,
175 	    UMA_ALIGN_PTR, 0);
176 	autofs_node_zone = uma_zcreate("autofs_node",
177 	    sizeof(struct autofs_node), NULL, NULL, NULL, NULL,
178 	    UMA_ALIGN_PTR, 0);
179 
180 	TAILQ_INIT(&autofs_softc->sc_requests);
181 	cv_init(&autofs_softc->sc_cv, "autofscv");
182 	sx_init(&autofs_softc->sc_lock, "autofslk");
183 
184 	error = make_dev_p(MAKEDEV_CHECKNAME, &autofs_softc->sc_cdev,
185 	    &autofs_cdevsw, NULL, UID_ROOT, GID_WHEEL, 0600, "autofs");
186 	if (error != 0) {
187 		AUTOFS_WARN("failed to create device node, error %d", error);
188 		uma_zdestroy(autofs_request_zone);
189 		uma_zdestroy(autofs_node_zone);
190 		free(autofs_softc, M_AUTOFS);
191 
192 		return (error);
193 	}
194 	autofs_softc->sc_cdev->si_drv1 = autofs_softc;
195 
196 	return (0);
197 }
198 
199 int
200 autofs_uninit(struct vfsconf *vfsp)
201 {
202 
203 	sx_xlock(&autofs_softc->sc_lock);
204 	if (autofs_softc->sc_dev_opened) {
205 		sx_xunlock(&autofs_softc->sc_lock);
206 		return (EBUSY);
207 	}
208 	if (autofs_softc->sc_cdev != NULL)
209 		destroy_dev(autofs_softc->sc_cdev);
210 
211 	uma_zdestroy(autofs_request_zone);
212 	uma_zdestroy(autofs_node_zone);
213 
214 	sx_xunlock(&autofs_softc->sc_lock);
215 	/*
216 	 * XXX: Race with open?
217 	 */
218 	free(autofs_softc, M_AUTOFS);
219 
220 	return (0);
221 }
222 
223 bool
224 autofs_ignore_thread(const struct thread *td)
225 {
226 	struct proc *p;
227 
228 	p = td->td_proc;
229 
230 	if (autofs_softc->sc_dev_opened == false)
231 		return (false);
232 
233 	PROC_LOCK(p);
234 	if (p->p_session->s_sid == autofs_softc->sc_dev_sid) {
235 		PROC_UNLOCK(p);
236 		return (true);
237 	}
238 	PROC_UNLOCK(p);
239 
240 	return (false);
241 }
242 
243 static char *
244 autofs_path(struct autofs_node *anp)
245 {
246 	struct autofs_mount *amp;
247 	char *path, *tmp;
248 
249 	amp = anp->an_mount;
250 
251 	path = strdup("", M_AUTOFS);
252 	for (; anp->an_parent != NULL; anp = anp->an_parent) {
253 		tmp = malloc(strlen(anp->an_name) + strlen(path) + 2,
254 		    M_AUTOFS, M_WAITOK);
255 		strcpy(tmp, anp->an_name);
256 		strcat(tmp, "/");
257 		strcat(tmp, path);
258 		free(path, M_AUTOFS);
259 		path = tmp;
260 	}
261 
262 	tmp = malloc(strlen(amp->am_mountpoint) + strlen(path) + 2,
263 	    M_AUTOFS, M_WAITOK);
264 	strcpy(tmp, amp->am_mountpoint);
265 	strcat(tmp, "/");
266 	strcat(tmp, path);
267 	free(path, M_AUTOFS);
268 	path = tmp;
269 
270 	return (path);
271 }
272 
273 static void
274 autofs_task(void *context, int pending)
275 {
276 	struct autofs_request *ar;
277 
278 	ar = context;
279 
280 	sx_xlock(&autofs_softc->sc_lock);
281 	AUTOFS_WARN("request %d for %s timed out after %d seconds",
282 	    ar->ar_id, ar->ar_path, autofs_timeout);
283 	/*
284 	 * XXX: EIO perhaps?
285 	 */
286 	ar->ar_error = ETIMEDOUT;
287 	ar->ar_wildcards = true;
288 	ar->ar_done = true;
289 	ar->ar_in_progress = false;
290 	cv_broadcast(&autofs_softc->sc_cv);
291 	sx_xunlock(&autofs_softc->sc_lock);
292 }
293 
294 bool
295 autofs_cached(struct autofs_node *anp, const char *component, int componentlen)
296 {
297 	int error;
298 	struct autofs_mount *amp;
299 
300 	amp = anp->an_mount;
301 
302 	AUTOFS_ASSERT_UNLOCKED(amp);
303 
304 	/*
305 	 * For root node we need to request automountd(8) assistance even
306 	 * if the node is marked as cached, but the requested top-level
307 	 * directory does not exist.  This is necessary for wildcard indirect
308 	 * map keys to work.  We don't do this if we know that there are
309 	 * no wildcards.
310 	 */
311 	if (anp->an_parent == NULL && componentlen != 0 && anp->an_wildcards) {
312 		AUTOFS_SLOCK(amp);
313 		error = autofs_node_find(anp, component, componentlen, NULL);
314 		AUTOFS_SUNLOCK(amp);
315 		if (error != 0)
316 			return (false);
317 	}
318 
319 	return (anp->an_cached);
320 }
321 
322 static void
323 autofs_cache_callout(void *context)
324 {
325 	struct autofs_node *anp;
326 
327 	anp = context;
328 	anp->an_cached = false;
329 }
330 
331 void
332 autofs_flush(struct autofs_mount *amp)
333 {
334 
335 	/*
336 	 * XXX: This will do for now, but ideally we should iterate
337 	 * 	over all the nodes.
338 	 */
339 	amp->am_root->an_cached = false;
340 	AUTOFS_DEBUG("%s flushed", amp->am_mountpoint);
341 }
342 
343 /*
344  * The set/restore sigmask functions are used to (temporarily) overwrite
345  * the thread td_sigmask during triggering.
346  */
347 static void
348 autofs_set_sigmask(sigset_t *oldset)
349 {
350 	sigset_t newset;
351 	int i;
352 
353 	SIGFILLSET(newset);
354 	/* Remove the autofs set of signals from newset */
355 	PROC_LOCK(curproc);
356 	mtx_lock(&curproc->p_sigacts->ps_mtx);
357 	for (i = 0 ; i < nitems(autofs_sig_set); i++) {
358 		/*
359 		 * But make sure we leave the ones already masked
360 		 * by the process, i.e. remove the signal from the
361 		 * temporary signalmask only if it wasn't already
362 		 * in p_sigmask.
363 		 */
364 		if (!SIGISMEMBER(curthread->td_sigmask, autofs_sig_set[i]) &&
365 		    !SIGISMEMBER(curproc->p_sigacts->ps_sigignore,
366 		    autofs_sig_set[i])) {
367 			SIGDELSET(newset, autofs_sig_set[i]);
368 		}
369 	}
370 	mtx_unlock(&curproc->p_sigacts->ps_mtx);
371 	kern_sigprocmask(curthread, SIG_SETMASK, &newset, oldset,
372 	    SIGPROCMASK_PROC_LOCKED);
373 	PROC_UNLOCK(curproc);
374 }
375 
376 static void
377 autofs_restore_sigmask(sigset_t *set)
378 {
379 
380 	kern_sigprocmask(curthread, SIG_SETMASK, set, NULL, 0);
381 }
382 
383 static int
384 autofs_trigger_one(struct autofs_node *anp,
385     const char *component, int componentlen)
386 {
387 	sigset_t oldset;
388 	struct autofs_mount *amp;
389 	struct autofs_node *firstanp;
390 	struct autofs_request *ar;
391 	char *key, *path;
392 	int error = 0, request_error, last;
393 	bool wildcards;
394 
395 	amp = anp->an_mount;
396 
397 	sx_assert(&autofs_softc->sc_lock, SA_XLOCKED);
398 
399 	if (anp->an_parent == NULL) {
400 		key = strndup(component, componentlen, M_AUTOFS);
401 	} else {
402 		for (firstanp = anp; firstanp->an_parent->an_parent != NULL;
403 		    firstanp = firstanp->an_parent)
404 			continue;
405 		key = strdup(firstanp->an_name, M_AUTOFS);
406 	}
407 
408 	path = autofs_path(anp);
409 
410 	TAILQ_FOREACH(ar, &autofs_softc->sc_requests, ar_next) {
411 		if (strcmp(ar->ar_path, path) != 0)
412 			continue;
413 		if (strcmp(ar->ar_key, key) != 0)
414 			continue;
415 
416 		KASSERT(strcmp(ar->ar_from, amp->am_from) == 0,
417 		    ("from changed; %s != %s", ar->ar_from, amp->am_from));
418 		KASSERT(strcmp(ar->ar_prefix, amp->am_prefix) == 0,
419 		    ("prefix changed; %s != %s",
420 		     ar->ar_prefix, amp->am_prefix));
421 		KASSERT(strcmp(ar->ar_options, amp->am_options) == 0,
422 		    ("options changed; %s != %s",
423 		     ar->ar_options, amp->am_options));
424 
425 		break;
426 	}
427 
428 	if (ar != NULL) {
429 		refcount_acquire(&ar->ar_refcount);
430 	} else {
431 		ar = uma_zalloc(autofs_request_zone, M_WAITOK | M_ZERO);
432 		ar->ar_mount = amp;
433 
434 		ar->ar_id =
435 		    atomic_fetchadd_int(&autofs_softc->sc_last_request_id, 1);
436 		strlcpy(ar->ar_from, amp->am_from, sizeof(ar->ar_from));
437 		strlcpy(ar->ar_path, path, sizeof(ar->ar_path));
438 		strlcpy(ar->ar_prefix, amp->am_prefix, sizeof(ar->ar_prefix));
439 		strlcpy(ar->ar_key, key, sizeof(ar->ar_key));
440 		strlcpy(ar->ar_options,
441 		    amp->am_options, sizeof(ar->ar_options));
442 
443 		TIMEOUT_TASK_INIT(taskqueue_thread, &ar->ar_task, 0,
444 		    autofs_task, ar);
445 		error = taskqueue_enqueue_timeout(taskqueue_thread,
446 		    &ar->ar_task, autofs_timeout * hz);
447 		if (error != 0) {
448 			AUTOFS_WARN("taskqueue_enqueue_timeout() failed "
449 			    "with error %d", error);
450 		}
451 		refcount_init(&ar->ar_refcount, 1);
452 		TAILQ_INSERT_TAIL(&autofs_softc->sc_requests, ar, ar_next);
453 	}
454 
455 	cv_broadcast(&autofs_softc->sc_cv);
456 	while (ar->ar_done == false) {
457 		if (autofs_interruptible != 0) {
458 			autofs_set_sigmask(&oldset);
459 			error = cv_wait_sig(&autofs_softc->sc_cv,
460 			    &autofs_softc->sc_lock);
461 			autofs_restore_sigmask(&oldset);
462 			if (error != 0) {
463 				AUTOFS_WARN("cv_wait_sig for %s failed "
464 				    "with error %d", ar->ar_path, error);
465 				break;
466 			}
467 		} else {
468 			cv_wait(&autofs_softc->sc_cv, &autofs_softc->sc_lock);
469 		}
470 	}
471 
472 	request_error = ar->ar_error;
473 	if (request_error != 0) {
474 		AUTOFS_WARN("request for %s completed with error %d",
475 		    ar->ar_path, request_error);
476 	}
477 
478 	wildcards = ar->ar_wildcards;
479 
480 	last = refcount_release(&ar->ar_refcount);
481 	if (last) {
482 		TAILQ_REMOVE(&autofs_softc->sc_requests, ar, ar_next);
483 		/*
484 		 * Unlock the sc_lock, so that autofs_task() can complete.
485 		 */
486 		sx_xunlock(&autofs_softc->sc_lock);
487 		taskqueue_cancel_timeout(taskqueue_thread, &ar->ar_task, NULL);
488 		taskqueue_drain_timeout(taskqueue_thread, &ar->ar_task);
489 		uma_zfree(autofs_request_zone, ar);
490 		sx_xlock(&autofs_softc->sc_lock);
491 	}
492 
493 	/*
494 	 * Note that we do not do negative caching on purpose.  This
495 	 * way the user can retry access at any time, e.g. after fixing
496 	 * the failure reason, without waiting for cache timer to expire.
497 	 */
498 	if (error == 0 && request_error == 0 && autofs_cache > 0) {
499 		anp->an_cached = true;
500 		anp->an_wildcards = wildcards;
501 		callout_reset(&anp->an_callout, autofs_cache * hz,
502 		    autofs_cache_callout, anp);
503 	}
504 
505 	free(key, M_AUTOFS);
506 	free(path, M_AUTOFS);
507 
508 	if (error != 0)
509 		return (error);
510 	return (request_error);
511 }
512 
513 /*
514  * Send request to automountd(8) and wait for completion.
515  */
516 int
517 autofs_trigger(struct autofs_node *anp,
518     const char *component, int componentlen)
519 {
520 	int error;
521 
522 	for (;;) {
523 		error = autofs_trigger_one(anp, component, componentlen);
524 		if (error == 0) {
525 			anp->an_retries = 0;
526 			return (0);
527 		}
528 		if (error == EINTR || error == ERESTART) {
529 			AUTOFS_DEBUG("trigger interrupted by signal, "
530 			    "not retrying");
531 			anp->an_retries = 0;
532 			return (error);
533 		}
534 		anp->an_retries++;
535 		if (anp->an_retries >= autofs_retry_attempts) {
536 			AUTOFS_DEBUG("trigger failed %d times; returning "
537 			    "error %d", anp->an_retries, error);
538 			anp->an_retries = 0;
539 			return (error);
540 
541 		}
542 		AUTOFS_DEBUG("trigger failed with error %d; will retry in "
543 		    "%d seconds, %d attempts left", error, autofs_retry_delay,
544 		    autofs_retry_attempts - anp->an_retries);
545 		sx_xunlock(&autofs_softc->sc_lock);
546 		pause("autofs_retry", autofs_retry_delay * hz);
547 		sx_xlock(&autofs_softc->sc_lock);
548 	}
549 }
550 
551 static int
552 autofs_ioctl_request(struct autofs_daemon_request *adr)
553 {
554 	struct autofs_request *ar;
555 	int error;
556 
557 	sx_xlock(&autofs_softc->sc_lock);
558 	for (;;) {
559 		TAILQ_FOREACH(ar, &autofs_softc->sc_requests, ar_next) {
560 			if (ar->ar_done)
561 				continue;
562 			if (ar->ar_in_progress)
563 				continue;
564 
565 			break;
566 		}
567 
568 		if (ar != NULL)
569 			break;
570 
571 		error = cv_wait_sig(&autofs_softc->sc_cv,
572 		    &autofs_softc->sc_lock);
573 		if (error != 0) {
574 			sx_xunlock(&autofs_softc->sc_lock);
575 			return (error);
576 		}
577 	}
578 
579 	ar->ar_in_progress = true;
580 	sx_xunlock(&autofs_softc->sc_lock);
581 
582 	adr->adr_id = ar->ar_id;
583 	strlcpy(adr->adr_from, ar->ar_from, sizeof(adr->adr_from));
584 	strlcpy(adr->adr_path, ar->ar_path, sizeof(adr->adr_path));
585 	strlcpy(adr->adr_prefix, ar->ar_prefix, sizeof(adr->adr_prefix));
586 	strlcpy(adr->adr_key, ar->ar_key, sizeof(adr->adr_key));
587 	strlcpy(adr->adr_options, ar->ar_options, sizeof(adr->adr_options));
588 
589 	PROC_LOCK(curproc);
590 	autofs_softc->sc_dev_sid = curproc->p_session->s_sid;
591 	PROC_UNLOCK(curproc);
592 
593 	return (0);
594 }
595 
596 static int
597 autofs_ioctl_done_101(struct autofs_daemon_done_101 *add)
598 {
599 	struct autofs_request *ar;
600 
601 	sx_xlock(&autofs_softc->sc_lock);
602 	TAILQ_FOREACH(ar, &autofs_softc->sc_requests, ar_next) {
603 		if (ar->ar_id == add->add_id)
604 			break;
605 	}
606 
607 	if (ar == NULL) {
608 		sx_xunlock(&autofs_softc->sc_lock);
609 		AUTOFS_DEBUG("id %d not found", add->add_id);
610 		return (ESRCH);
611 	}
612 
613 	ar->ar_error = add->add_error;
614 	ar->ar_wildcards = true;
615 	ar->ar_done = true;
616 	ar->ar_in_progress = false;
617 	cv_broadcast(&autofs_softc->sc_cv);
618 
619 	sx_xunlock(&autofs_softc->sc_lock);
620 
621 	return (0);
622 }
623 
624 static int
625 autofs_ioctl_done(struct autofs_daemon_done *add)
626 {
627 	struct autofs_request *ar;
628 
629 	sx_xlock(&autofs_softc->sc_lock);
630 	TAILQ_FOREACH(ar, &autofs_softc->sc_requests, ar_next) {
631 		if (ar->ar_id == add->add_id)
632 			break;
633 	}
634 
635 	if (ar == NULL) {
636 		sx_xunlock(&autofs_softc->sc_lock);
637 		AUTOFS_DEBUG("id %d not found", add->add_id);
638 		return (ESRCH);
639 	}
640 
641 	ar->ar_error = add->add_error;
642 	ar->ar_wildcards = add->add_wildcards;
643 	ar->ar_done = true;
644 	ar->ar_in_progress = false;
645 	cv_broadcast(&autofs_softc->sc_cv);
646 
647 	sx_xunlock(&autofs_softc->sc_lock);
648 
649 	return (0);
650 }
651 
652 static int
653 autofs_open(struct cdev *dev, int flags, int fmt, struct thread *td)
654 {
655 
656 	sx_xlock(&autofs_softc->sc_lock);
657 	/*
658 	 * We must never block automountd(8) and its descendants, and we use
659 	 * session ID to determine that: we store session id of the process
660 	 * that opened the device, and then compare it with session ids
661 	 * of triggering processes.  This means running a second automountd(8)
662 	 * instance would break the previous one.  The check below prevents
663 	 * it from happening.
664 	 */
665 	if (autofs_softc->sc_dev_opened) {
666 		sx_xunlock(&autofs_softc->sc_lock);
667 		return (EBUSY);
668 	}
669 
670 	autofs_softc->sc_dev_opened = true;
671 	sx_xunlock(&autofs_softc->sc_lock);
672 
673 	return (0);
674 }
675 
676 static int
677 autofs_close(struct cdev *dev, int flag, int fmt, struct thread *td)
678 {
679 
680 	sx_xlock(&autofs_softc->sc_lock);
681 	KASSERT(autofs_softc->sc_dev_opened, ("not opened?"));
682 	autofs_softc->sc_dev_opened = false;
683 	sx_xunlock(&autofs_softc->sc_lock);
684 
685 	return (0);
686 }
687 
688 static int
689 autofs_ioctl(struct cdev *dev, u_long cmd, caddr_t arg, int mode,
690     struct thread *td)
691 {
692 
693 	KASSERT(autofs_softc->sc_dev_opened, ("not opened?"));
694 
695 	switch (cmd) {
696 	case AUTOFSREQUEST:
697 		return (autofs_ioctl_request(
698 		    (struct autofs_daemon_request *)arg));
699 	case AUTOFSDONE101:
700 		return (autofs_ioctl_done_101(
701 		    (struct autofs_daemon_done_101 *)arg));
702 	case AUTOFSDONE:
703 		return (autofs_ioctl_done(
704 		    (struct autofs_daemon_done *)arg));
705 	default:
706 		AUTOFS_DEBUG("invalid cmd %lx", cmd);
707 		return (EINVAL);
708 	}
709 }
710