hooks.c revision 231017 
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: stable/9/sbin/hastd/hooks.c 231017 2012-02-05 15:51:19Z trociny $");
33
34#include <sys/types.h>
35#include <sys/sysctl.h>
36#include <sys/wait.h>
37
38#include <errno.h>
39#include <fcntl.h>
40#include <libgen.h>
41#include <paths.h>
42#include <signal.h>
43#include <stdbool.h>
44#include <stdint.h>
45#include <stdio.h>
46#include <stdlib.h>
47#include <string.h>
48#include <syslog.h>
49#include <unistd.h>
50
51#include <pjdlog.h>
52
53#include "hooks.h"
54#include "subr.h"
55#include "synch.h"
56
57/* Report processes that are running for too long not often than this value. */
58#define	REPORT_INTERVAL	60
59
60/* Are we initialized? */
61static bool hooks_initialized = false;
62
63/*
64 * Keep all processes we forked on a global queue, so we can report nicely
65 * when they finish or report that they are running for a long time.
66 */
67#define	HOOKPROC_MAGIC_ALLOCATED	0x80090ca
68#define	HOOKPROC_MAGIC_ONLIST		0x80090c0
69struct hookproc {
70	/* Magic. */
71	int	hp_magic;
72	/* PID of a forked child. */
73	pid_t	hp_pid;
74	/* When process were forked? */
75	time_t	hp_birthtime;
76	/* When we logged previous reported? */
77	time_t	hp_lastreport;
78	/* Path to executable and all the arguments we passed. */
79	char	hp_comm[PATH_MAX];
80	TAILQ_ENTRY(hookproc) hp_next;
81};
82static TAILQ_HEAD(, hookproc) hookprocs;
83static pthread_mutex_t hookprocs_lock;
84
85static void hook_remove(struct hookproc *hp);
86static void hook_free(struct hookproc *hp);
87
88static void
89descriptors(void)
90{
91	int fd;
92
93	/*
94	 * Close all (or almost all) descriptors.
95	 */
96	if (pjdlog_mode_get() == PJDLOG_MODE_STD) {
97		closefrom(MAX(MAX(STDIN_FILENO, STDOUT_FILENO),
98		    STDERR_FILENO) + 1);
99		return;
100	}
101
102	closefrom(0);
103
104	/*
105	 * Redirect stdin, stdout and stderr to /dev/null.
106	 */
107	fd = open(_PATH_DEVNULL, O_RDONLY);
108	if (fd == -1) {
109		pjdlog_errno(LOG_WARNING, "Unable to open %s for reading",
110		    _PATH_DEVNULL);
111	} else if (fd != STDIN_FILENO) {
112		if (dup2(fd, STDIN_FILENO) == -1) {
113			pjdlog_errno(LOG_WARNING,
114			    "Unable to duplicate descriptor for stdin");
115		}
116		close(fd);
117	}
118	fd = open(_PATH_DEVNULL, O_WRONLY);
119	if (fd == -1) {
120		pjdlog_errno(LOG_WARNING, "Unable to open %s for writing",
121		    _PATH_DEVNULL);
122	} else {
123		if (fd != STDOUT_FILENO && dup2(fd, STDOUT_FILENO) == -1) {
124			pjdlog_errno(LOG_WARNING,
125			    "Unable to duplicate descriptor for stdout");
126		}
127		if (fd != STDERR_FILENO && dup2(fd, STDERR_FILENO) == -1) {
128			pjdlog_errno(LOG_WARNING,
129			    "Unable to duplicate descriptor for stderr");
130		}
131		if (fd != STDOUT_FILENO && fd != STDERR_FILENO)
132			close(fd);
133	}
134}
135
136void
137hook_init(void)
138{
139
140	PJDLOG_ASSERT(!hooks_initialized);
141
142	mtx_init(&hookprocs_lock);
143	TAILQ_INIT(&hookprocs);
144	hooks_initialized = true;
145}
146
147void
148hook_fini(void)
149{
150	struct hookproc *hp;
151
152	PJDLOG_ASSERT(hooks_initialized);
153
154	mtx_lock(&hookprocs_lock);
155	while ((hp = TAILQ_FIRST(&hookprocs)) != NULL) {
156		PJDLOG_ASSERT(hp->hp_magic == HOOKPROC_MAGIC_ONLIST);
157		PJDLOG_ASSERT(hp->hp_pid > 0);
158
159		hook_remove(hp);
160		hook_free(hp);
161	}
162	mtx_unlock(&hookprocs_lock);
163
164	mtx_destroy(&hookprocs_lock);
165	TAILQ_INIT(&hookprocs);
166	hooks_initialized = false;
167}
168
169static struct hookproc *
170hook_alloc(const char *path, char **args)
171{
172	struct hookproc *hp;
173	unsigned int ii;
174
175	hp = malloc(sizeof(*hp));
176	if (hp == NULL) {
177		pjdlog_error("Unable to allocate %zu bytes of memory for a hook.",
178		    sizeof(*hp));
179		return (NULL);
180	}
181
182	hp->hp_pid = 0;
183	hp->hp_birthtime = hp->hp_lastreport = time(NULL);
184	(void)strlcpy(hp->hp_comm, path, sizeof(hp->hp_comm));
185	/* We start at 2nd argument as we don't want to have exec name twice. */
186	for (ii = 1; args[ii] != NULL; ii++) {
187		(void)snprlcat(hp->hp_comm, sizeof(hp->hp_comm), " %s",
188		    args[ii]);
189	}
190	if (strlen(hp->hp_comm) >= sizeof(hp->hp_comm) - 1) {
191		pjdlog_error("Exec path too long, correct configuration file.");
192		free(hp);
193		return (NULL);
194	}
195	hp->hp_magic = HOOKPROC_MAGIC_ALLOCATED;
196	return (hp);
197}
198
199static void
200hook_add(struct hookproc *hp, pid_t pid)
201{
202
203	PJDLOG_ASSERT(hp->hp_magic == HOOKPROC_MAGIC_ALLOCATED);
204	PJDLOG_ASSERT(hp->hp_pid == 0);
205
206	hp->hp_pid = pid;
207	mtx_lock(&hookprocs_lock);
208	hp->hp_magic = HOOKPROC_MAGIC_ONLIST;
209	TAILQ_INSERT_TAIL(&hookprocs, hp, hp_next);
210	mtx_unlock(&hookprocs_lock);
211}
212
213static void
214hook_remove(struct hookproc *hp)
215{
216
217	PJDLOG_ASSERT(hp->hp_magic == HOOKPROC_MAGIC_ONLIST);
218	PJDLOG_ASSERT(hp->hp_pid > 0);
219	PJDLOG_ASSERT(mtx_owned(&hookprocs_lock));
220
221	TAILQ_REMOVE(&hookprocs, hp, hp_next);
222	hp->hp_magic = HOOKPROC_MAGIC_ALLOCATED;
223}
224
225static void
226hook_free(struct hookproc *hp)
227{
228
229	PJDLOG_ASSERT(hp->hp_magic == HOOKPROC_MAGIC_ALLOCATED);
230	PJDLOG_ASSERT(hp->hp_pid > 0);
231
232	hp->hp_magic = 0;
233	free(hp);
234}
235
236static struct hookproc *
237hook_find(pid_t pid)
238{
239	struct hookproc *hp;
240
241	PJDLOG_ASSERT(mtx_owned(&hookprocs_lock));
242
243	TAILQ_FOREACH(hp, &hookprocs, hp_next) {
244		PJDLOG_ASSERT(hp->hp_magic == HOOKPROC_MAGIC_ONLIST);
245		PJDLOG_ASSERT(hp->hp_pid > 0);
246
247		if (hp->hp_pid == pid)
248			break;
249	}
250
251	return (hp);
252}
253
254void
255hook_check_one(pid_t pid, int status)
256{
257	struct hookproc *hp;
258
259	mtx_lock(&hookprocs_lock);
260	hp = hook_find(pid);
261	if (hp == NULL) {
262		mtx_unlock(&hookprocs_lock);
263		pjdlog_debug(1, "Unknown process pid=%u", pid);
264		return;
265	}
266	hook_remove(hp);
267	mtx_unlock(&hookprocs_lock);
268	if (WIFEXITED(status) && WEXITSTATUS(status) == 0) {
269		pjdlog_debug(1, "Hook exited gracefully (pid=%u, cmd=[%s]).",
270		    pid, hp->hp_comm);
271	} else if (WIFSIGNALED(status)) {
272		pjdlog_error("Hook was killed (pid=%u, signal=%d, cmd=[%s]).",
273		    pid, WTERMSIG(status), hp->hp_comm);
274	} else {
275		pjdlog_error("Hook exited ungracefully (pid=%u, exitcode=%d, cmd=[%s]).",
276		    pid, WIFEXITED(status) ? WEXITSTATUS(status) : -1,
277		    hp->hp_comm);
278	}
279	hook_free(hp);
280}
281
282void
283hook_check(void)
284{
285	struct hookproc *hp, *hp2;
286	time_t now;
287
288	PJDLOG_ASSERT(hooks_initialized);
289
290	pjdlog_debug(2, "Checking hooks.");
291
292	/*
293	 * Report about processes that are running for a long time.
294	 */
295	now = time(NULL);
296	mtx_lock(&hookprocs_lock);
297	TAILQ_FOREACH_SAFE(hp, &hookprocs, hp_next, hp2) {
298		PJDLOG_ASSERT(hp->hp_magic == HOOKPROC_MAGIC_ONLIST);
299		PJDLOG_ASSERT(hp->hp_pid > 0);
300
301		/*
302		 * If process doesn't exists we somehow missed it.
303		 * Not much can be done expect for logging this situation.
304		 */
305		if (kill(hp->hp_pid, 0) == -1 && errno == ESRCH) {
306			pjdlog_warning("Hook disappeared (pid=%u, cmd=[%s]).",
307			    hp->hp_pid, hp->hp_comm);
308			hook_remove(hp);
309			hook_free(hp);
310			continue;
311		}
312
313		/*
314		 * Skip proccesses younger than 1 minute.
315		 */
316		if (now - hp->hp_lastreport < REPORT_INTERVAL)
317			continue;
318
319		/*
320		 * Hook is running for too long, report it.
321		 */
322		pjdlog_warning("Hook is running for %ju seconds (pid=%u, cmd=[%s]).",
323		    (uintmax_t)(now - hp->hp_birthtime), hp->hp_pid,
324		    hp->hp_comm);
325		hp->hp_lastreport = now;
326	}
327	mtx_unlock(&hookprocs_lock);
328}
329
330void
331hook_exec(const char *path, ...)
332{
333	va_list ap;
334
335	va_start(ap, path);
336	hook_execv(path, ap);
337	va_end(ap);
338}
339
340void
341hook_execv(const char *path, va_list ap)
342{
343	struct hookproc *hp;
344	char *args[64];
345	unsigned int ii;
346	sigset_t mask;
347	pid_t pid;
348
349	PJDLOG_ASSERT(hooks_initialized);
350
351	if (path == NULL || path[0] == '\0')
352		return;
353
354	memset(args, 0, sizeof(args));
355	args[0] = basename(path);
356	for (ii = 1; ii < sizeof(args) / sizeof(args[0]); ii++) {
357		args[ii] = va_arg(ap, char *);
358		if (args[ii] == NULL)
359			break;
360	}
361	PJDLOG_ASSERT(ii < sizeof(args) / sizeof(args[0]));
362
363	hp = hook_alloc(path, args);
364	if (hp == NULL)
365		return;
366
367	pjdlog_debug(1, "Executing hook: %s", hp->hp_comm);
368
369	pid = fork();
370	switch (pid) {
371	case -1:	/* Error. */
372		pjdlog_errno(LOG_ERR, "Unable to fork to execute %s", path);
373		hook_free(hp);
374		return;
375	case 0:		/* Child. */
376		descriptors();
377		PJDLOG_VERIFY(sigemptyset(&mask) == 0);
378		PJDLOG_VERIFY(sigprocmask(SIG_SETMASK, &mask, NULL) == 0);
379		/*
380		 * Dummy handler set for SIGCHLD in the parent will be restored
381		 * to SIG_IGN on execv(3) below, so there is no need to do
382		 * anything with it.
383		 */
384		execv(path, args);
385		pjdlog_errno(LOG_ERR, "Unable to execute %s", path);
386		exit(EX_SOFTWARE);
387	default:	/* Parent. */
388		hook_add(hp, pid);
389		break;
390	}
391}
392