automountd.c revision 283235 
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#include <sys/cdefs.h>
32__FBSDID("$FreeBSD: stable/10/usr.sbin/autofs/automountd.c 283235 2015-05-21 13:31:44Z trasz $");
33
34#include <sys/types.h>
35#include <sys/time.h>
36#include <sys/ioctl.h>
37#include <sys/param.h>
38#include <sys/linker.h>
39#include <sys/mount.h>
40#include <sys/socket.h>
41#include <sys/stat.h>
42#include <sys/wait.h>
43#include <sys/utsname.h>
44#include <assert.h>
45#include <ctype.h>
46#include <errno.h>
47#include <fcntl.h>
48#include <libgen.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 <libutil.h>
59
60#include "autofs_ioctl.h"
61
62#include "common.h"
63
64#define AUTOMOUNTD_PIDFILE	"/var/run/automountd.pid"
65
66static int nchildren = 0;
67static int autofs_fd;
68static int request_id;
69
70static void
71done(int request_error, bool wildcards)
72{
73	struct autofs_daemon_done add;
74	int error;
75
76	memset(&add, 0, sizeof(add));
77	add.add_id = request_id;
78	add.add_wildcards = wildcards;
79	add.add_error = request_error;
80
81	log_debugx("completing request %d with error %d",
82	    request_id, request_error);
83
84	error = ioctl(autofs_fd, AUTOFSDONE, &add);
85	if (error != 0)
86		log_warn("AUTOFSDONE");
87}
88
89/*
90 * Remove "fstype=whatever" from optionsp and return the "whatever" part.
91 */
92static char *
93pick_option(const char *option, char **optionsp)
94{
95	char *tofree, *pair, *newoptions;
96	char *picked = NULL;
97	bool first = true;
98
99	tofree = *optionsp;
100
101	newoptions = calloc(strlen(*optionsp) + 1, 1);
102	if (newoptions == NULL)
103		log_err(1, "calloc");
104
105	while ((pair = strsep(optionsp, ",")) != NULL) {
106		/*
107		 * XXX: strncasecmp(3) perhaps?
108		 */
109		if (strncmp(pair, option, strlen(option)) == 0) {
110			picked = checked_strdup(pair + strlen(option));
111		} else {
112			if (first == false)
113				strcat(newoptions, ",");
114			else
115				first = false;
116			strcat(newoptions, pair);
117		}
118	}
119
120	free(tofree);
121	*optionsp = newoptions;
122
123	return (picked);
124}
125
126static void
127create_subtree(const struct node *node, bool incomplete)
128{
129	const struct node *child;
130	char *path;
131	bool wildcard_found = false;
132
133	/*
134	 * Skip wildcard nodes.
135	 */
136	if (strcmp(node->n_key, "*") == 0)
137		return;
138
139	path = node_path(node);
140	log_debugx("creating subtree at %s", path);
141	create_directory(path);
142
143	if (incomplete) {
144		TAILQ_FOREACH(child, &node->n_children, n_next) {
145			if (strcmp(child->n_key, "*") == 0) {
146				wildcard_found = true;
147				break;
148			}
149		}
150
151		if (wildcard_found) {
152			log_debugx("node %s contains wildcard entry; "
153			    "not creating its subdirectories due to -d flag",
154			    path);
155			free(path);
156			return;
157		}
158	}
159
160	free(path);
161
162	TAILQ_FOREACH(child, &node->n_children, n_next)
163		create_subtree(child, incomplete);
164}
165
166static void
167exit_callback(void)
168{
169
170	done(EIO, true);
171}
172
173static void
174handle_request(const struct autofs_daemon_request *adr, char *cmdline_options,
175    bool incomplete_hierarchy)
176{
177	const char *map;
178	struct node *root, *parent, *node;
179	FILE *f;
180	char *options, *fstype, *nobrowse, *retrycnt, *tmp;
181	int error;
182	bool wildcards;
183
184	log_debugx("got request %d: from %s, path %s, prefix \"%s\", "
185	    "key \"%s\", options \"%s\"", adr->adr_id, adr->adr_from,
186	    adr->adr_path, adr->adr_prefix, adr->adr_key, adr->adr_options);
187
188	/*
189	 * Try to notify the kernel about any problems.
190	 */
191	request_id = adr->adr_id;
192	atexit(exit_callback);
193
194	if (strncmp(adr->adr_from, "map ", 4) != 0) {
195		log_errx(1, "invalid mountfrom \"%s\"; failing request",
196		    adr->adr_from);
197	}
198
199	map = adr->adr_from + 4; /* 4 for strlen("map "); */
200	root = node_new_root();
201	if (adr->adr_prefix[0] == '\0' || strcmp(adr->adr_prefix, "/") == 0) {
202		parent = root;
203	} else {
204		parent = node_new_map(root, checked_strdup(adr->adr_prefix),
205		    NULL,  checked_strdup(map),
206		    checked_strdup("[kernel request]"), lineno);
207	}
208
209	/*
210	 * "Wildcards" here actually means "make autofs(4) request
211	 * automountd(8) action if the node being looked up does not
212	 * exist, even though the parent is marked as cached".  This
213	 * needs to be done for maps with wildcard entries, but also
214	 * for special and executable maps.
215	 */
216	parse_map(parent, map, adr->adr_key[0] != '\0' ? adr->adr_key : NULL,
217	    &wildcards);
218	if (!wildcards)
219		wildcards = node_has_wildcards(parent);
220	if (wildcards)
221		log_debugx("map may contain wildcard entries");
222	else
223		log_debugx("map does not contain wildcard entries");
224
225	if (adr->adr_key[0] != '\0')
226		node_expand_wildcard(root, adr->adr_key);
227
228	node = node_find(root, adr->adr_path);
229	if (node == NULL) {
230		log_errx(1, "map %s does not contain key for \"%s\"; "
231		    "failing mount", map, adr->adr_path);
232	}
233
234	options = node_options(node);
235	options = concat(adr->adr_options, ',', options);
236
237	/*
238	 * Prepend options passed via automountd(8) command line.
239	 */
240	if (cmdline_options != NULL)
241		options = concat(cmdline_options, ',', options);
242
243	if (node->n_location == NULL) {
244		log_debugx("found node defined at %s:%d; not a mountpoint",
245		    node->n_config_file, node->n_config_line);
246
247		nobrowse = pick_option("nobrowse", &options);
248		if (nobrowse != NULL && adr->adr_key[0] == '\0') {
249			log_debugx("skipping map %s due to \"nobrowse\" "
250			    "option; exiting", map);
251			done(0, true);
252
253			/*
254			 * Exit without calling exit_callback().
255			 */
256			quick_exit(0);
257		}
258
259		/*
260		 * Not a mountpoint; create directories in the autofs mount
261		 * and complete the request.
262		 */
263		create_subtree(node, incomplete_hierarchy);
264
265		if (incomplete_hierarchy && adr->adr_key[0] != '\0') {
266			/*
267			 * We still need to create the single subdirectory
268			 * user is trying to access.
269			 */
270			tmp = concat(adr->adr_path, '/', adr->adr_key);
271			node = node_find(root, tmp);
272			if (node != NULL)
273				create_subtree(node, false);
274		}
275
276		log_debugx("nothing to mount; exiting");
277		done(0, wildcards);
278
279		/*
280		 * Exit without calling exit_callback().
281		 */
282		quick_exit(0);
283	}
284
285	log_debugx("found node defined at %s:%d; it is a mountpoint",
286	    node->n_config_file, node->n_config_line);
287
288	node_expand_ampersand(node,
289	    adr->adr_key[0] != '\0' ? adr->adr_key : NULL);
290	error = node_expand_defined(node);
291	if (error != 0) {
292		log_errx(1, "variable expansion failed for %s; "
293		    "failing mount", adr->adr_path);
294	}
295
296	/*
297	 * Append "automounted".
298	 */
299	options = concat(options, ',', "automounted");
300
301	/*
302	 * Remove "nobrowse", mount(8) doesn't understand it.
303	 */
304	pick_option("nobrowse", &options);
305
306	/*
307	 * Figure out fstype.
308	 */
309	fstype = pick_option("fstype=", &options);
310	if (fstype == NULL) {
311		log_debugx("fstype not specified in options; "
312		    "defaulting to \"nfs\"");
313		fstype = checked_strdup("nfs");
314	}
315
316	if (strcmp(fstype, "nfs") == 0) {
317		/*
318		 * The mount_nfs(8) command defaults to retry undefinitely.
319		 * We do not want that behaviour, because it leaves mount_nfs(8)
320		 * instances and automountd(8) children hanging forever.
321		 * Disable retries unless the option was passed explicitly.
322		 */
323		retrycnt = pick_option("retrycnt=", &options);
324		if (retrycnt == NULL) {
325			log_debugx("retrycnt not specified in options; "
326			    "defaulting to 1");
327			options = concat(options, ',', "retrycnt=1");
328		} else {
329			options = concat(options, ',',
330			    concat("retrycnt", '=', retrycnt));
331		}
332	}
333
334	f = auto_popen("mount", "-t", fstype, "-o", options,
335	    node->n_location, adr->adr_path, NULL);
336	assert(f != NULL);
337	error = auto_pclose(f);
338	if (error != 0)
339		log_errx(1, "mount failed");
340
341	log_debugx("mount done; exiting");
342	done(0, wildcards);
343
344	/*
345	 * Exit without calling exit_callback().
346	 */
347	quick_exit(0);
348}
349
350static void
351sigchld_handler(int dummy __unused)
352{
353
354	/*
355	 * The only purpose of this handler is to make SIGCHLD
356	 * interrupt the AUTOFSREQUEST ioctl(2), so we can call
357	 * wait_for_children().
358	 */
359}
360
361static void
362register_sigchld(void)
363{
364	struct sigaction sa;
365	int error;
366
367	bzero(&sa, sizeof(sa));
368	sa.sa_handler = sigchld_handler;
369	sigfillset(&sa.sa_mask);
370	error = sigaction(SIGCHLD, &sa, NULL);
371	if (error != 0)
372		log_err(1, "sigaction");
373
374}
375
376
377static int
378wait_for_children(bool block)
379{
380	pid_t pid;
381	int status;
382	int num = 0;
383
384	for (;;) {
385		/*
386		 * If "block" is true, wait for at least one process.
387		 */
388		if (block && num == 0)
389			pid = wait4(-1, &status, 0, NULL);
390		else
391			pid = wait4(-1, &status, WNOHANG, NULL);
392		if (pid <= 0)
393			break;
394		if (WIFSIGNALED(status)) {
395			log_warnx("child process %d terminated with signal %d",
396			    pid, WTERMSIG(status));
397		} else if (WEXITSTATUS(status) != 0) {
398			log_debugx("child process %d terminated with exit status %d",
399			    pid, WEXITSTATUS(status));
400		} else {
401			log_debugx("child process %d terminated gracefully", pid);
402		}
403		num++;
404	}
405
406	return (num);
407}
408
409static void
410usage_automountd(void)
411{
412
413	fprintf(stderr, "usage: automountd [-D name=value][-m maxproc]"
414	    "[-o opts][-Tidv]\n");
415	exit(1);
416}
417
418int
419main_automountd(int argc, char **argv)
420{
421	struct pidfh *pidfh;
422	pid_t pid, otherpid;
423	const char *pidfile_path = AUTOMOUNTD_PIDFILE;
424	char *options = NULL;
425	struct autofs_daemon_request request;
426	int ch, debug = 0, error, maxproc = 30, retval, saved_errno;
427	bool dont_daemonize = false, incomplete_hierarchy = false;
428
429	defined_init();
430
431	while ((ch = getopt(argc, argv, "D:Tdim:o:v")) != -1) {
432		switch (ch) {
433		case 'D':
434			defined_parse_and_add(optarg);
435			break;
436		case 'T':
437			/*
438			 * For compatibility with other implementations,
439			 * such as OS X.
440			 */
441			debug++;
442			break;
443		case 'd':
444			dont_daemonize = true;
445			debug++;
446			break;
447		case 'i':
448			incomplete_hierarchy = true;
449			break;
450		case 'm':
451			maxproc = atoi(optarg);
452			break;
453		case 'o':
454			if (options == NULL) {
455				options = checked_strdup(optarg);
456			} else {
457				options = concat(options, ',', optarg);
458			}
459			break;
460		case 'v':
461			debug++;
462			break;
463		case '?':
464		default:
465			usage_automountd();
466		}
467	}
468	argc -= optind;
469	if (argc != 0)
470		usage_automountd();
471
472	log_init(debug);
473
474	pidfh = pidfile_open(pidfile_path, 0600, &otherpid);
475	if (pidfh == NULL) {
476		if (errno == EEXIST) {
477			log_errx(1, "daemon already running, pid: %jd.",
478			    (intmax_t)otherpid);
479		}
480		log_err(1, "cannot open or create pidfile \"%s\"",
481		    pidfile_path);
482	}
483
484	autofs_fd = open(AUTOFS_PATH, O_RDWR | O_CLOEXEC);
485	if (autofs_fd < 0 && errno == ENOENT) {
486		saved_errno = errno;
487		retval = kldload("autofs");
488		if (retval != -1)
489			autofs_fd = open(AUTOFS_PATH, O_RDWR | O_CLOEXEC);
490		else
491			errno = saved_errno;
492	}
493	if (autofs_fd < 0)
494		log_err(1, "failed to open %s", AUTOFS_PATH);
495
496	if (dont_daemonize == false) {
497		if (daemon(0, 0) == -1) {
498			log_warn("cannot daemonize");
499			pidfile_remove(pidfh);
500			exit(1);
501		}
502	} else {
503		lesser_daemon();
504	}
505
506	pidfile_write(pidfh);
507
508	register_sigchld();
509
510	for (;;) {
511		log_debugx("waiting for request from the kernel");
512
513		memset(&request, 0, sizeof(request));
514		error = ioctl(autofs_fd, AUTOFSREQUEST, &request);
515		if (error != 0) {
516			if (errno == EINTR) {
517				nchildren -= wait_for_children(false);
518				assert(nchildren >= 0);
519				continue;
520			}
521
522			log_err(1, "AUTOFSREQUEST");
523		}
524
525		if (dont_daemonize) {
526			log_debugx("not forking due to -d flag; "
527			    "will exit after servicing a single request");
528		} else {
529			nchildren -= wait_for_children(false);
530			assert(nchildren >= 0);
531
532			while (maxproc > 0 && nchildren >= maxproc) {
533				log_debugx("maxproc limit of %d child processes hit; "
534				    "waiting for child process to exit", maxproc);
535				nchildren -= wait_for_children(true);
536				assert(nchildren >= 0);
537			}
538			log_debugx("got request; forking child process #%d",
539			    nchildren);
540			nchildren++;
541
542			pid = fork();
543			if (pid < 0)
544				log_err(1, "fork");
545			if (pid > 0)
546				continue;
547		}
548
549		pidfile_close(pidfh);
550		handle_request(&request, options, incomplete_hierarchy);
551	}
552
553	pidfile_close(pidfh);
554
555	return (0);
556}
557
558