1/*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 2010 The FreeBSD Foundation
5 * Copyright (c) 2010 Pawel Jakub Dawidek <pjd@FreeBSD.org>
6 * All rights reserved.
7 *
8 * This software was developed by Pawel Jakub Dawidek under sponsorship from
9 * the FreeBSD Foundation.
10 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
13 * are met:
14 * 1. Redistributions of source code must retain the above copyright
15 *    notice, this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 *    notice, this list of conditions and the following disclaimer in the
18 *    documentation and/or other materials provided with the distribution.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 */
32
33#include <sys/types.h>
34#include <sys/sysctl.h>
35#include <sys/wait.h>
36
37#include <errno.h>
38#include <fcntl.h>
39#include <paths.h>
40#include <signal.h>
41#include <stdbool.h>
42#include <stdint.h>
43#include <stdio.h>
44#include <stdlib.h>
45#include <string.h>
46#include <syslog.h>
47#include <unistd.h>
48
49#include <pjdlog.h>
50
51#include "hooks.h"
52#include "subr.h"
53#include "synch.h"
54
55/* Report processes that are running for too long not often than this value. */
56#define	REPORT_INTERVAL	60
57
58/* Are we initialized? */
59static bool hooks_initialized = false;
60
61/*
62 * Keep all processes we forked on a global queue, so we can report nicely
63 * when they finish or report that they are running for a long time.
64 */
65#define	HOOKPROC_MAGIC_ALLOCATED	0x80090ca
66#define	HOOKPROC_MAGIC_ONLIST		0x80090c0
67struct hookproc {
68	/* Magic. */
69	int	hp_magic;
70	/* PID of a forked child. */
71	pid_t	hp_pid;
72	/* When process were forked? */
73	time_t	hp_birthtime;
74	/* When we logged previous reported? */
75	time_t	hp_lastreport;
76	/* Path to executable and all the arguments we passed. */
77	char	hp_comm[PATH_MAX];
78	TAILQ_ENTRY(hookproc) hp_next;
79};
80static TAILQ_HEAD(, hookproc) hookprocs;
81static pthread_mutex_t hookprocs_lock;
82
83static void hook_remove(struct hookproc *hp);
84static void hook_free(struct hookproc *hp);
85
86static void
87descriptors(void)
88{
89	int fd;
90
91	/*
92	 * Close all (or almost all) descriptors.
93	 */
94	if (pjdlog_mode_get() == PJDLOG_MODE_STD) {
95		closefrom(MAX(MAX(STDIN_FILENO, STDOUT_FILENO),
96		    STDERR_FILENO) + 1);
97		return;
98	}
99
100	closefrom(0);
101
102	/*
103	 * Redirect stdin, stdout and stderr to /dev/null.
104	 */
105	fd = open(_PATH_DEVNULL, O_RDONLY);
106	if (fd == -1) {
107		pjdlog_errno(LOG_WARNING, "Unable to open %s for reading",
108		    _PATH_DEVNULL);
109	} else if (fd != STDIN_FILENO) {
110		if (dup2(fd, STDIN_FILENO) == -1) {
111			pjdlog_errno(LOG_WARNING,
112			    "Unable to duplicate descriptor for stdin");
113		}
114		close(fd);
115	}
116	fd = open(_PATH_DEVNULL, O_WRONLY);
117	if (fd == -1) {
118		pjdlog_errno(LOG_WARNING, "Unable to open %s for writing",
119		    _PATH_DEVNULL);
120	} else {
121		if (fd != STDOUT_FILENO && dup2(fd, STDOUT_FILENO) == -1) {
122			pjdlog_errno(LOG_WARNING,
123			    "Unable to duplicate descriptor for stdout");
124		}
125		if (fd != STDERR_FILENO && dup2(fd, STDERR_FILENO) == -1) {
126			pjdlog_errno(LOG_WARNING,
127			    "Unable to duplicate descriptor for stderr");
128		}
129		if (fd != STDOUT_FILENO && fd != STDERR_FILENO)
130			close(fd);
131	}
132}
133
134void
135hook_init(void)
136{
137
138	PJDLOG_ASSERT(!hooks_initialized);
139
140	mtx_init(&hookprocs_lock);
141	TAILQ_INIT(&hookprocs);
142	hooks_initialized = true;
143}
144
145void
146hook_fini(void)
147{
148	struct hookproc *hp;
149
150	PJDLOG_ASSERT(hooks_initialized);
151
152	mtx_lock(&hookprocs_lock);
153	while ((hp = TAILQ_FIRST(&hookprocs)) != NULL) {
154		PJDLOG_ASSERT(hp->hp_magic == HOOKPROC_MAGIC_ONLIST);
155		PJDLOG_ASSERT(hp->hp_pid > 0);
156
157		hook_remove(hp);
158		hook_free(hp);
159	}
160	mtx_unlock(&hookprocs_lock);
161
162	mtx_destroy(&hookprocs_lock);
163	TAILQ_INIT(&hookprocs);
164	hooks_initialized = false;
165}
166
167static struct hookproc *
168hook_alloc(const char *path, char **args)
169{
170	struct hookproc *hp;
171	unsigned int ii;
172
173	hp = malloc(sizeof(*hp));
174	if (hp == NULL) {
175		pjdlog_error("Unable to allocate %zu bytes of memory for a hook.",
176		    sizeof(*hp));
177		return (NULL);
178	}
179
180	hp->hp_pid = 0;
181	hp->hp_birthtime = hp->hp_lastreport = time(NULL);
182	(void)strlcpy(hp->hp_comm, path, sizeof(hp->hp_comm));
183	/* We start at 2nd argument as we don't want to have exec name twice. */
184	for (ii = 1; args[ii] != NULL; ii++) {
185		(void)snprlcat(hp->hp_comm, sizeof(hp->hp_comm), " %s",
186		    args[ii]);
187	}
188	if (strlen(hp->hp_comm) >= sizeof(hp->hp_comm) - 1) {
189		pjdlog_error("Exec path too long, correct configuration file.");
190		free(hp);
191		return (NULL);
192	}
193	hp->hp_magic = HOOKPROC_MAGIC_ALLOCATED;
194	return (hp);
195}
196
197static void
198hook_add(struct hookproc *hp, pid_t pid)
199{
200
201	PJDLOG_ASSERT(hp->hp_magic == HOOKPROC_MAGIC_ALLOCATED);
202	PJDLOG_ASSERT(hp->hp_pid == 0);
203
204	hp->hp_pid = pid;
205	mtx_lock(&hookprocs_lock);
206	hp->hp_magic = HOOKPROC_MAGIC_ONLIST;
207	TAILQ_INSERT_TAIL(&hookprocs, hp, hp_next);
208	mtx_unlock(&hookprocs_lock);
209}
210
211static void
212hook_remove(struct hookproc *hp)
213{
214
215	PJDLOG_ASSERT(hp->hp_magic == HOOKPROC_MAGIC_ONLIST);
216	PJDLOG_ASSERT(hp->hp_pid > 0);
217	PJDLOG_ASSERT(mtx_owned(&hookprocs_lock));
218
219	TAILQ_REMOVE(&hookprocs, hp, hp_next);
220	hp->hp_magic = HOOKPROC_MAGIC_ALLOCATED;
221}
222
223static void
224hook_free(struct hookproc *hp)
225{
226
227	PJDLOG_ASSERT(hp->hp_magic == HOOKPROC_MAGIC_ALLOCATED);
228	PJDLOG_ASSERT(hp->hp_pid > 0);
229
230	hp->hp_magic = 0;
231	free(hp);
232}
233
234static struct hookproc *
235hook_find(pid_t pid)
236{
237	struct hookproc *hp;
238
239	PJDLOG_ASSERT(mtx_owned(&hookprocs_lock));
240
241	TAILQ_FOREACH(hp, &hookprocs, hp_next) {
242		PJDLOG_ASSERT(hp->hp_magic == HOOKPROC_MAGIC_ONLIST);
243		PJDLOG_ASSERT(hp->hp_pid > 0);
244
245		if (hp->hp_pid == pid)
246			break;
247	}
248
249	return (hp);
250}
251
252void
253hook_check_one(pid_t pid, int status)
254{
255	struct hookproc *hp;
256
257	mtx_lock(&hookprocs_lock);
258	hp = hook_find(pid);
259	if (hp == NULL) {
260		mtx_unlock(&hookprocs_lock);
261		pjdlog_debug(1, "Unknown process pid=%u", pid);
262		return;
263	}
264	hook_remove(hp);
265	mtx_unlock(&hookprocs_lock);
266	if (WIFEXITED(status) && WEXITSTATUS(status) == 0) {
267		pjdlog_debug(1, "Hook exited gracefully (pid=%u, cmd=[%s]).",
268		    pid, hp->hp_comm);
269	} else if (WIFSIGNALED(status)) {
270		pjdlog_error("Hook was killed (pid=%u, signal=%d, cmd=[%s]).",
271		    pid, WTERMSIG(status), hp->hp_comm);
272	} else {
273		pjdlog_error("Hook exited ungracefully (pid=%u, exitcode=%d, cmd=[%s]).",
274		    pid, WIFEXITED(status) ? WEXITSTATUS(status) : -1,
275		    hp->hp_comm);
276	}
277	hook_free(hp);
278}
279
280void
281hook_check(void)
282{
283	struct hookproc *hp, *hp2;
284	time_t now;
285
286	PJDLOG_ASSERT(hooks_initialized);
287
288	pjdlog_debug(2, "Checking hooks.");
289
290	/*
291	 * Report about processes that are running for a long time.
292	 */
293	now = time(NULL);
294	mtx_lock(&hookprocs_lock);
295	TAILQ_FOREACH_SAFE(hp, &hookprocs, hp_next, hp2) {
296		PJDLOG_ASSERT(hp->hp_magic == HOOKPROC_MAGIC_ONLIST);
297		PJDLOG_ASSERT(hp->hp_pid > 0);
298
299		/*
300		 * If process doesn't exists we somehow missed it.
301		 * Not much can be done expect for logging this situation.
302		 */
303		if (kill(hp->hp_pid, 0) == -1 && errno == ESRCH) {
304			pjdlog_warning("Hook disappeared (pid=%u, cmd=[%s]).",
305			    hp->hp_pid, hp->hp_comm);
306			hook_remove(hp);
307			hook_free(hp);
308			continue;
309		}
310
311		/*
312		 * Skip processes younger than 1 minute.
313		 */
314		if (now - hp->hp_lastreport < REPORT_INTERVAL)
315			continue;
316
317		/*
318		 * Hook is running for too long, report it.
319		 */
320		pjdlog_warning("Hook is running for %ju seconds (pid=%u, cmd=[%s]).",
321		    (uintmax_t)(now - hp->hp_birthtime), hp->hp_pid,
322		    hp->hp_comm);
323		hp->hp_lastreport = now;
324	}
325	mtx_unlock(&hookprocs_lock);
326}
327
328void
329hook_exec(const char *path, ...)
330{
331	va_list ap;
332
333	va_start(ap, path);
334	hook_execv(path, ap);
335	va_end(ap);
336}
337
338void
339hook_execv(const char *path, va_list ap)
340{
341	struct hookproc *hp;
342	char *args[64];
343	unsigned int ii;
344	sigset_t mask;
345	pid_t pid;
346
347	PJDLOG_ASSERT(hooks_initialized);
348
349	if (path == NULL || path[0] == '\0')
350		return;
351
352	memset(args, 0, sizeof(args));
353	args[0] = __DECONST(char *, path);
354	for (ii = 1; ii < sizeof(args) / sizeof(args[0]); ii++) {
355		args[ii] = va_arg(ap, char *);
356		if (args[ii] == NULL)
357			break;
358	}
359	PJDLOG_ASSERT(ii < sizeof(args) / sizeof(args[0]));
360
361	hp = hook_alloc(path, args);
362	if (hp == NULL)
363		return;
364
365	pjdlog_debug(1, "Executing hook: %s", hp->hp_comm);
366
367	pid = fork();
368	switch (pid) {
369	case -1:	/* Error. */
370		pjdlog_errno(LOG_ERR, "Unable to fork to execute %s", path);
371		hook_free(hp);
372		return;
373	case 0:		/* Child. */
374		descriptors();
375		PJDLOG_VERIFY(sigemptyset(&mask) == 0);
376		PJDLOG_VERIFY(sigprocmask(SIG_SETMASK, &mask, NULL) == 0);
377		/*
378		 * Dummy handler set for SIGCHLD in the parent will be restored
379		 * to SIG_IGN on execv(3) below, so there is no need to do
380		 * anything with it.
381		 */
382		execv(path, args);
383		pjdlog_errno(LOG_ERR, "Unable to execute %s", path);
384		exit(EX_SOFTWARE);
385	default:	/* Parent. */
386		hook_add(hp, pid);
387		break;
388	}
389}
390