automountd.c revision 279743 
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 279743 2015-03-07 19:39:16Z 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		    checked_strdup(adr->adr_options), 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	if (node->n_location == NULL) {
235		log_debugx("found node defined at %s:%d; not a mountpoint",
236		    node->n_config_file, node->n_config_line);
237
238		options = node_options(node);
239
240		/*
241		 * Prepend options passed via automountd(8) command line.
242		 */
243		if (cmdline_options != NULL) {
244			options =
245			    separated_concat(cmdline_options, options, ',');
246		}
247
248		nobrowse = pick_option("nobrowse", &options);
249		if (nobrowse != NULL && adr->adr_key[0] == '\0') {
250			log_debugx("skipping map %s due to \"nobrowse\" "
251			    "option; exiting", map);
252			done(0, true);
253
254			/*
255			 * Exit without calling exit_callback().
256			 */
257			quick_exit(0);
258		}
259
260		/*
261		 * Not a mountpoint; create directories in the autofs mount
262		 * and complete the request.
263		 */
264		create_subtree(node, incomplete_hierarchy);
265
266		if (incomplete_hierarchy && adr->adr_key[0] != '\0') {
267			/*
268			 * We still need to create the single subdirectory
269			 * user is trying to access.
270			 */
271			tmp = separated_concat(adr->adr_path,
272			    adr->adr_key, '/');
273			node = node_find(root, tmp);
274			if (node != NULL)
275				create_subtree(node, false);
276		}
277
278		log_debugx("nothing to mount; exiting");
279		done(0, wildcards);
280
281		/*
282		 * Exit without calling exit_callback().
283		 */
284		quick_exit(0);
285	}
286
287	log_debugx("found node defined at %s:%d; it is a mountpoint",
288	    node->n_config_file, node->n_config_line);
289
290	node_expand_ampersand(node,
291	    adr->adr_key[0] != '\0' ? adr->adr_key : NULL);
292	error = node_expand_defined(node);
293	if (error != 0) {
294		log_errx(1, "variable expansion failed for %s; "
295		    "failing mount", adr->adr_path);
296	}
297
298	options = node_options(node);
299
300	/*
301	 * Prepend options passed via automountd(8) command line.
302	 */
303	if (cmdline_options != NULL)
304		options = separated_concat(cmdline_options, options, ',');
305
306	/*
307	 * Append "automounted".
308	 */
309	options = separated_concat(options, "automounted", ',');
310
311	/*
312	 * Remove "nobrowse", mount(8) doesn't understand it.
313	 */
314	pick_option("nobrowse", &options);
315
316	/*
317	 * Figure out fstype.
318	 */
319	fstype = pick_option("fstype=", &options);
320	if (fstype == NULL) {
321		log_debugx("fstype not specified in options; "
322		    "defaulting to \"nfs\"");
323		fstype = checked_strdup("nfs");
324	}
325
326	if (strcmp(fstype, "nfs") == 0) {
327		/*
328		 * The mount_nfs(8) command defaults to retry undefinitely.
329		 * We do not want that behaviour, because it leaves mount_nfs(8)
330		 * instances and automountd(8) children hanging forever.
331		 * Disable retries unless the option was passed explicitly.
332		 */
333		retrycnt = pick_option("retrycnt=", &options);
334		if (retrycnt == NULL) {
335			log_debugx("retrycnt not specified in options; "
336			    "defaulting to 1");
337			options = separated_concat(options,
338			    separated_concat("retrycnt", "1", '='), ',');
339		} else {
340			options = separated_concat(options,
341			    separated_concat("retrycnt", retrycnt, '='), ',');
342		}
343	}
344
345	f = auto_popen("mount", "-t", fstype, "-o", options,
346	    node->n_location, adr->adr_path, NULL);
347	assert(f != NULL);
348	error = auto_pclose(f);
349	if (error != 0)
350		log_errx(1, "mount failed");
351
352	log_debugx("mount done; exiting");
353	done(0, wildcards);
354
355	/*
356	 * Exit without calling exit_callback().
357	 */
358	quick_exit(0);
359}
360
361static void
362sigchld_handler(int dummy __unused)
363{
364
365	/*
366	 * The only purpose of this handler is to make SIGCHLD
367	 * interrupt the AUTOFSREQUEST ioctl(2), so we can call
368	 * wait_for_children().
369	 */
370}
371
372static void
373register_sigchld(void)
374{
375	struct sigaction sa;
376	int error;
377
378	bzero(&sa, sizeof(sa));
379	sa.sa_handler = sigchld_handler;
380	sigfillset(&sa.sa_mask);
381	error = sigaction(SIGCHLD, &sa, NULL);
382	if (error != 0)
383		log_err(1, "sigaction");
384
385}
386
387
388static int
389wait_for_children(bool block)
390{
391	pid_t pid;
392	int status;
393	int num = 0;
394
395	for (;;) {
396		/*
397		 * If "block" is true, wait for at least one process.
398		 */
399		if (block && num == 0)
400			pid = wait4(-1, &status, 0, NULL);
401		else
402			pid = wait4(-1, &status, WNOHANG, NULL);
403		if (pid <= 0)
404			break;
405		if (WIFSIGNALED(status)) {
406			log_warnx("child process %d terminated with signal %d",
407			    pid, WTERMSIG(status));
408		} else if (WEXITSTATUS(status) != 0) {
409			log_debugx("child process %d terminated with exit status %d",
410			    pid, WEXITSTATUS(status));
411		} else {
412			log_debugx("child process %d terminated gracefully", pid);
413		}
414		num++;
415	}
416
417	return (num);
418}
419
420static void
421usage_automountd(void)
422{
423
424	fprintf(stderr, "usage: automountd [-D name=value][-m maxproc]"
425	    "[-o opts][-Tidv]\n");
426	exit(1);
427}
428
429int
430main_automountd(int argc, char **argv)
431{
432	struct pidfh *pidfh;
433	pid_t pid, otherpid;
434	const char *pidfile_path = AUTOMOUNTD_PIDFILE;
435	char *options = NULL;
436	struct autofs_daemon_request request;
437	int ch, debug = 0, error, maxproc = 30, retval, saved_errno;
438	bool dont_daemonize = false, incomplete_hierarchy = false;
439
440	defined_init();
441
442	while ((ch = getopt(argc, argv, "D:Tdim:o:v")) != -1) {
443		switch (ch) {
444		case 'D':
445			defined_parse_and_add(optarg);
446			break;
447		case 'T':
448			/*
449			 * For compatibility with other implementations,
450			 * such as OS X.
451			 */
452			debug++;
453			break;
454		case 'd':
455			dont_daemonize = true;
456			debug++;
457			break;
458		case 'i':
459			incomplete_hierarchy = true;
460			break;
461		case 'm':
462			maxproc = atoi(optarg);
463			break;
464		case 'o':
465			if (options == NULL) {
466				options = checked_strdup(optarg);
467			} else {
468				options =
469				    separated_concat(options, optarg, ',');
470			}
471			break;
472		case 'v':
473			debug++;
474			break;
475		case '?':
476		default:
477			usage_automountd();
478		}
479	}
480	argc -= optind;
481	if (argc != 0)
482		usage_automountd();
483
484	log_init(debug);
485
486	pidfh = pidfile_open(pidfile_path, 0600, &otherpid);
487	if (pidfh == NULL) {
488		if (errno == EEXIST) {
489			log_errx(1, "daemon already running, pid: %jd.",
490			    (intmax_t)otherpid);
491		}
492		log_err(1, "cannot open or create pidfile \"%s\"",
493		    pidfile_path);
494	}
495
496	autofs_fd = open(AUTOFS_PATH, O_RDWR | O_CLOEXEC);
497	if (autofs_fd < 0 && errno == ENOENT) {
498		saved_errno = errno;
499		retval = kldload("autofs");
500		if (retval != -1)
501			autofs_fd = open(AUTOFS_PATH, O_RDWR | O_CLOEXEC);
502		else
503			errno = saved_errno;
504	}
505	if (autofs_fd < 0)
506		log_err(1, "failed to open %s", AUTOFS_PATH);
507
508	if (dont_daemonize == false) {
509		if (daemon(0, 0) == -1) {
510			log_warn("cannot daemonize");
511			pidfile_remove(pidfh);
512			exit(1);
513		}
514	} else {
515		lesser_daemon();
516	}
517
518	pidfile_write(pidfh);
519
520	register_sigchld();
521
522	for (;;) {
523		log_debugx("waiting for request from the kernel");
524
525		memset(&request, 0, sizeof(request));
526		error = ioctl(autofs_fd, AUTOFSREQUEST, &request);
527		if (error != 0) {
528			if (errno == EINTR) {
529				nchildren -= wait_for_children(false);
530				assert(nchildren >= 0);
531				continue;
532			}
533
534			log_err(1, "AUTOFSREQUEST");
535		}
536
537		if (dont_daemonize) {
538			log_debugx("not forking due to -d flag; "
539			    "will exit after servicing a single request");
540		} else {
541			nchildren -= wait_for_children(false);
542			assert(nchildren >= 0);
543
544			while (maxproc > 0 && nchildren >= maxproc) {
545				log_debugx("maxproc limit of %d child processes hit; "
546				    "waiting for child process to exit", maxproc);
547				nchildren -= wait_for_children(true);
548				assert(nchildren >= 0);
549			}
550			log_debugx("got request; forking child process #%d",
551			    nchildren);
552			nchildren++;
553
554			pid = fork();
555			if (pid < 0)
556				log_err(1, "fork");
557			if (pid > 0)
558				continue;
559		}
560
561		pidfile_close(pidfh);
562		handle_request(&request, options, incomplete_hierarchy);
563	}
564
565	pidfile_close(pidfh);
566
567	return (0);
568}
569
570