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("$FreeBSD$");
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? */
61 static 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
69 struct 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 };
82 static TAILQ_HEAD(, hookproc) hookprocs;
83 static pthread_mutex_t hookprocs_lock;
84
85 static void hook_remove(struct hookproc *hp);
86 static void hook_free(struct hookproc *hp);
87
88 static void
descriptors(void)89 descriptors(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
136 void
hook_init(void)137 hook_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
147 void
hook_fini(void)148 hook_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
169 static struct hookproc *
hook_alloc(const char * path,char ** args)170 hook_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
199 static void
hook_add(struct hookproc * hp,pid_t pid)200 hook_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
213 static void
hook_remove(struct hookproc * hp)214 hook_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
225 static void
hook_free(struct hookproc * hp)226 hook_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
236 static struct hookproc *
hook_find(pid_t pid)237 hook_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
254 void
hook_check_one(pid_t pid,int status)255 hook_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
282 void
hook_check(void)283 hook_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
330 void
hook_exec(const char * path,...)331 hook_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
340 void
hook_execv(const char * path,va_list ap)341 hook_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