xref: /freebsd/sbin/hastd/hooks.c (revision 9f23cbd6cae82fd77edfad7173432fa8dccd0a95)
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/cdefs.h>
34 __FBSDID("$FreeBSD$");
35 
36 #include <sys/types.h>
37 #include <sys/sysctl.h>
38 #include <sys/wait.h>
39 
40 #include <errno.h>
41 #include <fcntl.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? */
62 static 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
70 struct 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 };
83 static TAILQ_HEAD(, hookproc) hookprocs;
84 static pthread_mutex_t hookprocs_lock;
85 
86 static void hook_remove(struct hookproc *hp);
87 static void hook_free(struct hookproc *hp);
88 
89 static void
90 descriptors(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 == -1) {
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) == -1) {
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 == -1) {
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) == -1) {
125 			pjdlog_errno(LOG_WARNING,
126 			    "Unable to duplicate descriptor for stdout");
127 		}
128 		if (fd != STDERR_FILENO && dup2(fd, STDERR_FILENO) == -1) {
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 
137 void
138 hook_init(void)
139 {
140 
141 	PJDLOG_ASSERT(!hooks_initialized);
142 
143 	mtx_init(&hookprocs_lock);
144 	TAILQ_INIT(&hookprocs);
145 	hooks_initialized = true;
146 }
147 
148 void
149 hook_fini(void)
150 {
151 	struct hookproc *hp;
152 
153 	PJDLOG_ASSERT(hooks_initialized);
154 
155 	mtx_lock(&hookprocs_lock);
156 	while ((hp = TAILQ_FIRST(&hookprocs)) != NULL) {
157 		PJDLOG_ASSERT(hp->hp_magic == HOOKPROC_MAGIC_ONLIST);
158 		PJDLOG_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 
170 static struct hookproc *
171 hook_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 
200 static void
201 hook_add(struct hookproc *hp, pid_t pid)
202 {
203 
204 	PJDLOG_ASSERT(hp->hp_magic == HOOKPROC_MAGIC_ALLOCATED);
205 	PJDLOG_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 
214 static void
215 hook_remove(struct hookproc *hp)
216 {
217 
218 	PJDLOG_ASSERT(hp->hp_magic == HOOKPROC_MAGIC_ONLIST);
219 	PJDLOG_ASSERT(hp->hp_pid > 0);
220 	PJDLOG_ASSERT(mtx_owned(&hookprocs_lock));
221 
222 	TAILQ_REMOVE(&hookprocs, hp, hp_next);
223 	hp->hp_magic = HOOKPROC_MAGIC_ALLOCATED;
224 }
225 
226 static void
227 hook_free(struct hookproc *hp)
228 {
229 
230 	PJDLOG_ASSERT(hp->hp_magic == HOOKPROC_MAGIC_ALLOCATED);
231 	PJDLOG_ASSERT(hp->hp_pid > 0);
232 
233 	hp->hp_magic = 0;
234 	free(hp);
235 }
236 
237 static struct hookproc *
238 hook_find(pid_t pid)
239 {
240 	struct hookproc *hp;
241 
242 	PJDLOG_ASSERT(mtx_owned(&hookprocs_lock));
243 
244 	TAILQ_FOREACH(hp, &hookprocs, hp_next) {
245 		PJDLOG_ASSERT(hp->hp_magic == HOOKPROC_MAGIC_ONLIST);
246 		PJDLOG_ASSERT(hp->hp_pid > 0);
247 
248 		if (hp->hp_pid == pid)
249 			break;
250 	}
251 
252 	return (hp);
253 }
254 
255 void
256 hook_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 
283 void
284 hook_check(void)
285 {
286 	struct hookproc *hp, *hp2;
287 	time_t now;
288 
289 	PJDLOG_ASSERT(hooks_initialized);
290 
291 	pjdlog_debug(2, "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 		PJDLOG_ASSERT(hp->hp_magic == HOOKPROC_MAGIC_ONLIST);
300 		PJDLOG_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 processes 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 
331 void
332 hook_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 
341 void
342 hook_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 	PJDLOG_ASSERT(hooks_initialized);
351 
352 	if (path == NULL || path[0] == '\0')
353 		return;
354 
355 	memset(args, 0, sizeof(args));
356 	args[0] = __DECONST(char *, 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 	PJDLOG_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