hooks.c revision 219817 
1/*-
2 * Copyright (c) 2010 The FreeBSD Foundation
3 * Copyright (c) 2010 Pawel Jakub Dawidek <pjd@FreeBSD.org>
4 * All rights reserved.
5 *
6 * This software was developed by Pawel Jakub Dawidek under sponsorship from
7 * 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 AUTHORS 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 AUTHORS 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#include <sys/cdefs.h>
32__FBSDID("$FreeBSD: head/sbin/hastd/hooks.c 219817 2011-03-21 08:38:24Z pjd $");
33
34#include <sys/types.h>
35#include <sys/sysctl.h>
36#include <sys/wait.h>
37
38#include <assert.h>
39#include <errno.h>
40#include <fcntl.h>
41#include <libgen.h>
42#include <paths.h>
43#include <signal.h>
44#include <stdbool.h>
45#include <stdint.h>
46#include <stdio.h>
47#include <stdlib.h>
48#include <string.h>
49#include <syslog.h>
50#include <unistd.h>
51
52#include <pjdlog.h>
53
54#include "hooks.h"
55#include "subr.h"
56#include "synch.h"
57
58/* Report processes that are running for too long not often than this value. */
59#define	REPORT_INTERVAL	60
60
61/* Are we initialized? */
62static bool hooks_initialized = false;
63
64/*
65 * Keep all processes we forked on a global queue, so we can report nicely
66 * when they finish or report that they are running for a long time.
67 */
68#define	HOOKPROC_MAGIC_ALLOCATED	0x80090ca
69#define	HOOKPROC_MAGIC_ONLIST		0x80090c0
70struct hookproc {
71	/* Magic. */
72	int	hp_magic;
73	/* PID of a forked child. */
74	pid_t	hp_pid;
75	/* When process were forked? */
76	time_t	hp_birthtime;
77	/* When we logged previous reported? */
78	time_t	hp_lastreport;
79	/* Path to executable and all the arguments we passed. */
80	char	hp_comm[PATH_MAX];
81	TAILQ_ENTRY(hookproc) hp_next;
82};
83static TAILQ_HEAD(, hookproc) hookprocs;
84static pthread_mutex_t hookprocs_lock;
85
86static void hook_remove(struct hookproc *hp);
87static void hook_free(struct hookproc *hp);
88
89static void
90descriptors(void)
91{
92	int fd;
93
94	/*
95	 * Close all (or almost all) descriptors.
96	 */
97	if (pjdlog_mode_get() == PJDLOG_MODE_STD) {
98		closefrom(MAX(MAX(STDIN_FILENO, STDOUT_FILENO),
99		    STDERR_FILENO) + 1);
100		return;
101	}
102
103	closefrom(0);
104
105	/*
106	 * Redirect stdin, stdout and stderr to /dev/null.
107	 */
108	fd = open(_PATH_DEVNULL, O_RDONLY);
109	if (fd < 0) {
110		pjdlog_errno(LOG_WARNING, "Unable to open %s for reading",
111		    _PATH_DEVNULL);
112	} else if (fd != STDIN_FILENO) {
113		if (dup2(fd, STDIN_FILENO) < 0) {
114			pjdlog_errno(LOG_WARNING,
115			    "Unable to duplicate descriptor for stdin");
116		}
117		close(fd);
118	}
119	fd = open(_PATH_DEVNULL, O_WRONLY);
120	if (fd < 0) {
121		pjdlog_errno(LOG_WARNING, "Unable to open %s for writing",
122		    _PATH_DEVNULL);
123	} else {
124		if (fd != STDOUT_FILENO && dup2(fd, STDOUT_FILENO) < 0) {
125			pjdlog_errno(LOG_WARNING,
126			    "Unable to duplicate descriptor for stdout");
127		}
128		if (fd != STDERR_FILENO && dup2(fd, STDERR_FILENO) < 0) {
129			pjdlog_errno(LOG_WARNING,
130			    "Unable to duplicate descriptor for stderr");
131		}
132		if (fd != STDOUT_FILENO && fd != STDERR_FILENO)
133			close(fd);
134	}
135}
136
137void
138hook_init(void)
139{
140
141	assert(!hooks_initialized);
142
143	mtx_init(&hookprocs_lock);
144	TAILQ_INIT(&hookprocs);
145	hooks_initialized = true;
146}
147
148void
149hook_fini(void)
150{
151	struct hookproc *hp;
152
153	assert(hooks_initialized);
154
155	mtx_lock(&hookprocs_lock);
156	while ((hp = TAILQ_FIRST(&hookprocs)) != NULL) {
157		assert(hp->hp_magic == HOOKPROC_MAGIC_ONLIST);
158		assert(hp->hp_pid > 0);
159
160		hook_remove(hp);
161		hook_free(hp);
162	}
163	mtx_unlock(&hookprocs_lock);
164
165	mtx_destroy(&hookprocs_lock);
166	TAILQ_INIT(&hookprocs);
167	hooks_initialized = false;
168}
169
170static struct hookproc *
171hook_alloc(const char *path, char **args)
172{
173	struct hookproc *hp;
174	unsigned int ii;
175
176	hp = malloc(sizeof(*hp));
177	if (hp == NULL) {
178		pjdlog_error("Unable to allocate %zu bytes of memory for a hook.",
179		    sizeof(*hp));
180		return (NULL);
181	}
182
183	hp->hp_pid = 0;
184	hp->hp_birthtime = hp->hp_lastreport = time(NULL);
185	(void)strlcpy(hp->hp_comm, path, sizeof(hp->hp_comm));
186	/* We start at 2nd argument as we don't want to have exec name twice. */
187	for (ii = 1; args[ii] != NULL; ii++) {
188		(void)snprlcat(hp->hp_comm, sizeof(hp->hp_comm), " %s",
189		    args[ii]);
190	}
191	if (strlen(hp->hp_comm) >= sizeof(hp->hp_comm) - 1) {
192		pjdlog_error("Exec path too long, correct configuration file.");
193		free(hp);
194		return (NULL);
195	}
196	hp->hp_magic = HOOKPROC_MAGIC_ALLOCATED;
197	return (hp);
198}
199
200static void
201hook_add(struct hookproc *hp, pid_t pid)
202{
203
204	assert(hp->hp_magic == HOOKPROC_MAGIC_ALLOCATED);
205	assert(hp->hp_pid == 0);
206
207	hp->hp_pid = pid;
208	mtx_lock(&hookprocs_lock);
209	hp->hp_magic = HOOKPROC_MAGIC_ONLIST;
210	TAILQ_INSERT_TAIL(&hookprocs, hp, hp_next);
211	mtx_unlock(&hookprocs_lock);
212}
213
214static void
215hook_remove(struct hookproc *hp)
216{
217
218	assert(hp->hp_magic == HOOKPROC_MAGIC_ONLIST);
219	assert(hp->hp_pid > 0);
220	assert(mtx_owned(&hookprocs_lock));
221
222	TAILQ_REMOVE(&hookprocs, hp, hp_next);
223	hp->hp_magic = HOOKPROC_MAGIC_ALLOCATED;
224}
225
226static void
227hook_free(struct hookproc *hp)
228{
229
230	assert(hp->hp_magic == HOOKPROC_MAGIC_ALLOCATED);
231	assert(hp->hp_pid > 0);
232
233	hp->hp_magic = 0;
234	free(hp);
235}
236
237static struct hookproc *
238hook_find(pid_t pid)
239{
240	struct hookproc *hp;
241
242	assert(mtx_owned(&hookprocs_lock));
243
244	TAILQ_FOREACH(hp, &hookprocs, hp_next) {
245		assert(hp->hp_magic == HOOKPROC_MAGIC_ONLIST);
246		assert(hp->hp_pid > 0);
247
248		if (hp->hp_pid == pid)
249			break;
250	}
251
252	return (hp);
253}
254
255void
256hook_check_one(pid_t pid, int status)
257{
258	struct hookproc *hp;
259
260	mtx_lock(&hookprocs_lock);
261	hp = hook_find(pid);
262	if (hp == NULL) {
263		mtx_unlock(&hookprocs_lock);
264		pjdlog_debug(1, "Unknown process pid=%u", pid);
265		return;
266	}
267	hook_remove(hp);
268	mtx_unlock(&hookprocs_lock);
269	if (WIFEXITED(status) && WEXITSTATUS(status) == 0) {
270		pjdlog_debug(1, "Hook exited gracefully (pid=%u, cmd=[%s]).",
271		    pid, hp->hp_comm);
272	} else if (WIFSIGNALED(status)) {
273		pjdlog_error("Hook was killed (pid=%u, signal=%d, cmd=[%s]).",
274		    pid, WTERMSIG(status), hp->hp_comm);
275	} else {
276		pjdlog_error("Hook exited ungracefully (pid=%u, exitcode=%d, cmd=[%s]).",
277		    pid, WIFEXITED(status) ? WEXITSTATUS(status) : -1,
278		    hp->hp_comm);
279	}
280	hook_free(hp);
281}
282
283void
284hook_check(void)
285{
286	struct hookproc *hp, *hp2;
287	time_t now;
288
289	assert(hooks_initialized);
290
291	pjdlog_debug(1, "Checking hooks.");
292
293	/*
294	 * Report about processes that are running for a long time.
295	 */
296	now = time(NULL);
297	mtx_lock(&hookprocs_lock);
298	TAILQ_FOREACH_SAFE(hp, &hookprocs, hp_next, hp2) {
299		assert(hp->hp_magic == HOOKPROC_MAGIC_ONLIST);
300		assert(hp->hp_pid > 0);
301
302		/*
303		 * If process doesn't exists we somehow missed it.
304		 * Not much can be done expect for logging this situation.
305		 */
306		if (kill(hp->hp_pid, 0) == -1 && errno == ESRCH) {
307			pjdlog_warning("Hook disappeared (pid=%u, cmd=[%s]).",
308			    hp->hp_pid, hp->hp_comm);
309			hook_remove(hp);
310			hook_free(hp);
311			continue;
312		}
313
314		/*
315		 * Skip proccesses younger than 1 minute.
316		 */
317		if (now - hp->hp_lastreport < REPORT_INTERVAL)
318			continue;
319
320		/*
321		 * Hook is running for too long, report it.
322		 */
323		pjdlog_warning("Hook is running for %ju seconds (pid=%u, cmd=[%s]).",
324		    (uintmax_t)(now - hp->hp_birthtime), hp->hp_pid,
325		    hp->hp_comm);
326		hp->hp_lastreport = now;
327	}
328	mtx_unlock(&hookprocs_lock);
329}
330
331void
332hook_exec(const char *path, ...)
333{
334	va_list ap;
335
336	va_start(ap, path);
337	hook_execv(path, ap);
338	va_end(ap);
339}
340
341void
342hook_execv(const char *path, va_list ap)
343{
344	struct hookproc *hp;
345	char *args[64];
346	unsigned int ii;
347	sigset_t mask;
348	pid_t pid;
349
350	assert(hooks_initialized);
351
352	if (path == NULL || path[0] == '\0')
353		return;
354
355	memset(args, 0, sizeof(args));
356	args[0] = basename(path);
357	for (ii = 1; ii < sizeof(args) / sizeof(args[0]); ii++) {
358		args[ii] = va_arg(ap, char *);
359		if (args[ii] == NULL)
360			break;
361	}
362	assert(ii < sizeof(args) / sizeof(args[0]));
363
364	hp = hook_alloc(path, args);
365	if (hp == NULL)
366		return;
367
368	pjdlog_debug(1, "Executing hook: %s", hp->hp_comm);
369
370	pid = fork();
371	switch (pid) {
372	case -1:	/* Error. */
373		pjdlog_errno(LOG_ERR, "Unable to fork to execute %s", path);
374		hook_free(hp);
375		return;
376	case 0:		/* Child. */
377		descriptors();
378		PJDLOG_VERIFY(sigemptyset(&mask) == 0);
379		PJDLOG_VERIFY(sigprocmask(SIG_SETMASK, &mask, NULL) == 0);
380		/*
381		 * Dummy handler set for SIGCHLD in the parent will be restored
382		 * to SIG_IGN on execv(3) below, so there is no need to do
383		 * anything with it.
384		 */
385		execv(path, args);
386		pjdlog_errno(LOG_ERR, "Unable to execute %s", path);
387		exit(EX_SOFTWARE);
388	default:	/* Parent. */
389		hook_add(hp, pid);
390		break;
391	}
392}
393