xref: /freebsd/usr.sbin/autofs/automountd.c (revision d0b2dbfa0ecf2bbc9709efc5e20baf8e4b44bbbf) 
1 /*-
2  * SPDX-License-Identifier: BSD-2-Clause
3  *
4  * Copyright (c) 2014 The FreeBSD Foundation
5  *
6  * This software was developed by Edward Tomasz Napierala under sponsorship
7  * from the FreeBSD Foundation.
8  *
9  * Redistribution and use in source and binary forms, with or without
10  * modification, are permitted provided that the following conditions
11  * are met:
12  * 1. Redistributions of source code must retain the above copyright
13  *    notice, this list of conditions and the following disclaimer.
14  * 2. Redistributions in binary form must reproduce the above copyright
15  *    notice, this list of conditions and the following disclaimer in the
16  *    documentation and/or other materials provided with the distribution.
17  *
18  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
19  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
22  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28  * SUCH DAMAGE.
29  *
30  */
31 
32 #include <sys/cdefs.h>
33 #include <sys/types.h>
34 #include <sys/time.h>
35 #include <sys/ioctl.h>
36 #include <sys/param.h>
37 #include <sys/linker.h>
38 #include <sys/mount.h>
39 #include <sys/socket.h>
40 #include <sys/stat.h>
41 #include <sys/wait.h>
42 #include <sys/utsname.h>
43 #include <assert.h>
44 #include <ctype.h>
45 #include <errno.h>
46 #include <fcntl.h>
47 #include <libgen.h>
48 #include <libutil.h>
49 #include <netdb.h>
50 #include <signal.h>
51 #include <stdbool.h>
52 #include <stdint.h>
53 #include <stdio.h>
54 #include <stdlib.h>
55 #include <string.h>
56 #include <unistd.h>
57 
58 #include "autofs_ioctl.h"
59 
60 #include "common.h"
61 
62 #define AUTOMOUNTD_PIDFILE	"/var/run/automountd.pid"
63 
64 static int nchildren = 0;
65 static int autofs_fd;
66 static int request_id;
67 
68 static void
69 done(int request_error, bool wildcards)
70 {
71 	struct autofs_daemon_done add;
72 	int error;
73 
74 	memset(&add, 0, sizeof(add));
75 	add.add_id = request_id;
76 	add.add_wildcards = wildcards;
77 	add.add_error = request_error;
78 
79 	log_debugx("completing request %d with error %d",
80 	    request_id, request_error);
81 
82 	error = ioctl(autofs_fd, AUTOFSDONE, &add);
83 	if (error != 0)
84 		log_warn("AUTOFSDONE");
85 }
86 
87 /*
88  * Remove "fstype=whatever" from optionsp and return the "whatever" part.
89  */
90 static char *
91 pick_option(const char *option, char **optionsp)
92 {
93 	char *tofree, *pair, *newoptions;
94 	char *picked = NULL;
95 	bool first = true;
96 
97 	tofree = *optionsp;
98 
99 	newoptions = calloc(1, strlen(*optionsp) + 1);
100 	if (newoptions == NULL)
101 		log_err(1, "calloc");
102 
103 	while ((pair = strsep(optionsp, ",")) != NULL) {
104 		/*
105 		 * XXX: strncasecmp(3) perhaps?
106 		 */
107 		if (strncmp(pair, option, strlen(option)) == 0) {
108 			picked = checked_strdup(pair + strlen(option));
109 		} else {
110 			if (first == false)
111 				strcat(newoptions, ",");
112 			else
113 				first = false;
114 			strcat(newoptions, pair);
115 		}
116 	}
117 
118 	free(tofree);
119 	*optionsp = newoptions;
120 
121 	return (picked);
122 }
123 
124 static void
125 create_subtree(const struct node *node, bool incomplete)
126 {
127 	const struct node *child;
128 	char *path;
129 	bool wildcard_found = false;
130 
131 	/*
132 	 * Skip wildcard nodes.
133 	 */
134 	if (strcmp(node->n_key, "*") == 0)
135 		return;
136 
137 	path = node_path(node);
138 	log_debugx("creating subtree at %s", path);
139 	create_directory(path);
140 
141 	if (incomplete) {
142 		TAILQ_FOREACH(child, &node->n_children, n_next) {
143 			if (strcmp(child->n_key, "*") == 0) {
144 				wildcard_found = true;
145 				break;
146 			}
147 		}
148 
149 		if (wildcard_found) {
150 			log_debugx("node %s contains wildcard entry; "
151 			    "not creating its subdirectories due to -d flag",
152 			    path);
153 			free(path);
154 			return;
155 		}
156 	}
157 
158 	free(path);
159 
160 	TAILQ_FOREACH(child, &node->n_children, n_next)
161 		create_subtree(child, incomplete);
162 }
163 
164 static void
165 exit_callback(void)
166 {
167 
168 	done(EIO, true);
169 }
170 
171 static void
172 handle_request(const struct autofs_daemon_request *adr, char *cmdline_options,
173     bool incomplete_hierarchy)
174 {
175 	const char *map;
176 	struct node *root, *parent, *node;
177 	FILE *f;
178 	char *key, *options, *fstype, *nobrowse, *retrycnt, *tmp;
179 	int error;
180 	bool wildcards;
181 
182 	log_debugx("got request %d: from %s, path %s, prefix \"%s\", "
183 	    "key \"%s\", options \"%s\"", adr->adr_id, adr->adr_from,
184 	    adr->adr_path, adr->adr_prefix, adr->adr_key, adr->adr_options);
185 
186 	/*
187 	 * Try to notify the kernel about any problems.
188 	 */
189 	request_id = adr->adr_id;
190 	atexit(exit_callback);
191 
192 	if (strncmp(adr->adr_from, "map ", 4) != 0) {
193 		log_errx(1, "invalid mountfrom \"%s\"; failing request",
194 		    adr->adr_from);
195 	}
196 
197 	map = adr->adr_from + 4; /* 4 for strlen("map "); */
198 	root = node_new_root();
199 	if (adr->adr_prefix[0] == '\0' || strcmp(adr->adr_prefix, "/") == 0) {
200 		/*
201 		 * Direct map.  autofs(4) doesn't have a way to determine
202 		 * correct map key, but since it's a direct map, we can just
203 		 * use adr_path instead.
204 		 */
205 		parent = root;
206 		key = checked_strdup(adr->adr_path);
207 	} else {
208 		/*
209 		 * Indirect map.
210 		 */
211 		parent = node_new_map(root, checked_strdup(adr->adr_prefix),
212 		    NULL,  checked_strdup(map),
213 		    checked_strdup("[kernel request]"), lineno);
214 
215 		if (adr->adr_key[0] == '\0')
216 			key = NULL;
217 		else
218 			key = checked_strdup(adr->adr_key);
219 	}
220 
221 	/*
222 	 * "Wildcards" here actually means "make autofs(4) request
223 	 * automountd(8) action if the node being looked up does not
224 	 * exist, even though the parent is marked as cached".  This
225 	 * needs to be done for maps with wildcard entries, but also
226 	 * for special and executable maps.
227 	 */
228 	parse_map(parent, map, key, &wildcards);
229 	if (!wildcards)
230 		wildcards = node_has_wildcards(parent);
231 	if (wildcards)
232 		log_debugx("map may contain wildcard entries");
233 	else
234 		log_debugx("map does not contain wildcard entries");
235 
236 	if (key != NULL)
237 		node_expand_wildcard(root, key);
238 
239 	node = node_find(root, adr->adr_path);
240 	if (node == NULL) {
241 		log_errx(1, "map %s does not contain key for \"%s\"; "
242 		    "failing mount", map, adr->adr_path);
243 	}
244 
245 	options = node_options(node);
246 
247 	/*
248 	 * Append options from auto_master.
249 	 */
250 	options = concat(options, ',', adr->adr_options);
251 
252 	/*
253 	 * Prepend options passed via automountd(8) command line.
254 	 */
255 	options = concat(cmdline_options, ',', options);
256 
257 	if (node->n_location == NULL) {
258 		log_debugx("found node defined at %s:%d; not a mountpoint",
259 		    node->n_config_file, node->n_config_line);
260 
261 		nobrowse = pick_option("nobrowse", &options);
262 		if (nobrowse != NULL && key == NULL) {
263 			log_debugx("skipping map %s due to \"nobrowse\" "
264 			    "option; exiting", map);
265 			done(0, true);
266 
267 			/*
268 			 * Exit without calling exit_callback().
269 			 */
270 			quick_exit(0);
271 		}
272 
273 		/*
274 		 * Not a mountpoint; create directories in the autofs mount
275 		 * and complete the request.
276 		 */
277 		create_subtree(node, incomplete_hierarchy);
278 
279 		if (incomplete_hierarchy && key != NULL) {
280 			/*
281 			 * We still need to create the single subdirectory
282 			 * user is trying to access.
283 			 */
284 			tmp = concat(adr->adr_path, '/', key);
285 			node = node_find(root, tmp);
286 			if (node != NULL)
287 				create_subtree(node, false);
288 		}
289 
290 		log_debugx("nothing to mount; exiting");
291 		done(0, wildcards);
292 
293 		/*
294 		 * Exit without calling exit_callback().
295 		 */
296 		quick_exit(0);
297 	}
298 
299 	log_debugx("found node defined at %s:%d; it is a mountpoint",
300 	    node->n_config_file, node->n_config_line);
301 
302 	if (key != NULL)
303 		node_expand_ampersand(node, key);
304 	error = node_expand_defined(node);
305 	if (error != 0) {
306 		log_errx(1, "variable expansion failed for %s; "
307 		    "failing mount", adr->adr_path);
308 	}
309 
310 	/*
311 	 * Append "automounted".
312 	 */
313 	options = concat(options, ',', "automounted");
314 
315 	/*
316 	 * Remove "nobrowse", mount(8) doesn't understand it.
317 	 */
318 	pick_option("nobrowse", &options);
319 
320 	/*
321 	 * Figure out fstype.
322 	 */
323 	fstype = pick_option("fstype=", &options);
324 	if (fstype == NULL) {
325 		log_debugx("fstype not specified in options; "
326 		    "defaulting to \"nfs\"");
327 		fstype = checked_strdup("nfs");
328 	}
329 
330 	if (strcmp(fstype, "nfs") == 0) {
331 		/*
332 		 * The mount_nfs(8) command defaults to retry undefinitely.
333 		 * We do not want that behaviour, because it leaves mount_nfs(8)
334 		 * instances and automountd(8) children hanging forever.
335 		 * Disable retries unless the option was passed explicitly.
336 		 */
337 		retrycnt = pick_option("retrycnt=", &options);
338 		if (retrycnt == NULL) {
339 			log_debugx("retrycnt not specified in options; "
340 			    "defaulting to 1");
341 			options = concat(options, ',', "retrycnt=1");
342 		} else {
343 			options = concat(options, ',',
344 			    concat("retrycnt", '=', retrycnt));
345 		}
346 	}
347 
348 	f = auto_popen("mount", "-t", fstype, "-o", options,
349 	    node->n_location, adr->adr_path, NULL);
350 	assert(f != NULL);
351 	error = auto_pclose(f);
352 	if (error != 0)
353 		log_errx(1, "mount failed");
354 
355 	log_debugx("mount done; exiting");
356 	done(0, wildcards);
357 
358 	/*
359 	 * Exit without calling exit_callback().
360 	 */
361 	quick_exit(0);
362 }
363 
364 static void
365 sigchld_handler(int dummy __unused)
366 {
367 
368 	/*
369 	 * The only purpose of this handler is to make SIGCHLD
370 	 * interrupt the AUTOFSREQUEST ioctl(2), so we can call
371 	 * wait_for_children().
372 	 */
373 }
374 
375 static void
376 register_sigchld(void)
377 {
378 	struct sigaction sa;
379 	int error;
380 
381 	bzero(&sa, sizeof(sa));
382 	sa.sa_handler = sigchld_handler;
383 	sigfillset(&sa.sa_mask);
384 	error = sigaction(SIGCHLD, &sa, NULL);
385 	if (error != 0)
386 		log_err(1, "sigaction");
387 
388 }
389 
390 
391 static int
392 wait_for_children(bool block)
393 {
394 	pid_t pid;
395 	int status;
396 	int num = 0;
397 
398 	for (;;) {
399 		/*
400 		 * If "block" is true, wait for at least one process.
401 		 */
402 		if (block && num == 0)
403 			pid = wait4(-1, &status, 0, NULL);
404 		else
405 			pid = wait4(-1, &status, WNOHANG, NULL);
406 		if (pid <= 0)
407 			break;
408 		if (WIFSIGNALED(status)) {
409 			log_warnx("child process %d terminated with signal %d",
410 			    pid, WTERMSIG(status));
411 		} else if (WEXITSTATUS(status) != 0) {
412 			log_debugx("child process %d terminated with exit status %d",
413 			    pid, WEXITSTATUS(status));
414 		} else {
415 			log_debugx("child process %d terminated gracefully", pid);
416 		}
417 		num++;
418 	}
419 
420 	return (num);
421 }
422 
423 static void
424 usage_automountd(void)
425 {
426 
427 	fprintf(stderr, "usage: automountd [-D name=value][-m maxproc]"
428 	    "[-o opts][-Tidv]\n");
429 	exit(1);
430 }
431 
432 int
433 main_automountd(int argc, char **argv)
434 {
435 	struct pidfh *pidfh;
436 	pid_t pid, otherpid;
437 	const char *pidfile_path = AUTOMOUNTD_PIDFILE;
438 	char *options = NULL;
439 	struct autofs_daemon_request request;
440 	int ch, debug = 0, error, maxproc = 30, retval, saved_errno;
441 	bool dont_daemonize = false, incomplete_hierarchy = false;
442 
443 	defined_init();
444 
445 	while ((ch = getopt(argc, argv, "D:Tdim:o:v")) != -1) {
446 		switch (ch) {
447 		case 'D':
448 			defined_parse_and_add(optarg);
449 			break;
450 		case 'T':
451 			/*
452 			 * For compatibility with other implementations,
453 			 * such as OS X.
454 			 */
455 			debug++;
456 			break;
457 		case 'd':
458 			dont_daemonize = true;
459 			debug++;
460 			break;
461 		case 'i':
462 			incomplete_hierarchy = true;
463 			break;
464 		case 'm':
465 			maxproc = atoi(optarg);
466 			break;
467 		case 'o':
468 			options = concat(options, ',', optarg);
469 			break;
470 		case 'v':
471 			debug++;
472 			break;
473 		case '?':
474 		default:
475 			usage_automountd();
476 		}
477 	}
478 	argc -= optind;
479 	if (argc != 0)
480 		usage_automountd();
481 
482 	log_init(debug);
483 
484 	pidfh = pidfile_open(pidfile_path, 0600, &otherpid);
485 	if (pidfh == NULL) {
486 		if (errno == EEXIST) {
487 			log_errx(1, "daemon already running, pid: %jd.",
488 			    (intmax_t)otherpid);
489 		}
490 		log_err(1, "cannot open or create pidfile \"%s\"",
491 		    pidfile_path);
492 	}
493 
494 	autofs_fd = open(AUTOFS_PATH, O_RDWR | O_CLOEXEC);
495 	if (autofs_fd < 0 && errno == ENOENT) {
496 		saved_errno = errno;
497 		retval = kldload("autofs");
498 		if (retval != -1)
499 			autofs_fd = open(AUTOFS_PATH, O_RDWR | O_CLOEXEC);
500 		else
501 			errno = saved_errno;
502 	}
503 	if (autofs_fd < 0)
504 		log_err(1, "failed to open %s", AUTOFS_PATH);
505 
506 	if (dont_daemonize == false) {
507 		if (daemon(0, 0) == -1) {
508 			log_warn("cannot daemonize");
509 			pidfile_remove(pidfh);
510 			exit(1);
511 		}
512 	} else {
513 		lesser_daemon();
514 	}
515 
516 	pidfile_write(pidfh);
517 
518 	register_sigchld();
519 
520 	for (;;) {
521 		log_debugx("waiting for request from the kernel");
522 
523 		memset(&request, 0, sizeof(request));
524 		error = ioctl(autofs_fd, AUTOFSREQUEST, &request);
525 		if (error != 0) {
526 			if (errno == EINTR) {
527 				nchildren -= wait_for_children(false);
528 				assert(nchildren >= 0);
529 				continue;
530 			}
531 
532 			log_err(1, "AUTOFSREQUEST");
533 		}
534 
535 		if (dont_daemonize) {
536 			log_debugx("not forking due to -d flag; "
537 			    "will exit after servicing a single request");
538 		} else {
539 			nchildren -= wait_for_children(false);
540 			assert(nchildren >= 0);
541 
542 			while (maxproc > 0 && nchildren >= maxproc) {
543 				log_debugx("maxproc limit of %d child processes hit; "
544 				    "waiting for child process to exit", maxproc);
545 				nchildren -= wait_for_children(true);
546 				assert(nchildren >= 0);
547 			}
548 			log_debugx("got request; forking child process #%d",
549 			    nchildren);
550 			nchildren++;
551 
552 			pid = fork();
553 			if (pid < 0)
554 				log_err(1, "fork");
555 			if (pid > 0)
556 				continue;
557 		}
558 
559 		pidfile_close(pidfh);
560 		handle_request(&request, options, incomplete_hierarchy);
561 	}
562 
563 	pidfile_close(pidfh);
564 
565 	return (0);
566 }
567 
568