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? */
59 static 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
67 struct 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 };
80 static TAILQ_HEAD(, hookproc) hookprocs;
81 static pthread_mutex_t hookprocs_lock;
82
83 static void hook_remove(struct hookproc *hp);
84 static void hook_free(struct hookproc *hp);
85
86 static void
descriptors(void)87 descriptors(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
134 void
hook_init(void)135 hook_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
145 void
hook_fini(void)146 hook_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
167 static struct hookproc *
hook_alloc(const char * path,char ** args)168 hook_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
197 static void
hook_add(struct hookproc * hp,pid_t pid)198 hook_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
211 static void
hook_remove(struct hookproc * hp)212 hook_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
223 static void
hook_free(struct hookproc * hp)224 hook_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
234 static struct hookproc *
hook_find(pid_t pid)235 hook_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
252 void
hook_check_one(pid_t pid,int status)253 hook_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
280 void
hook_check(void)281 hook_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
328 void
hook_exec(const char * path,...)329 hook_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
338 void
hook_execv(const char * path,va_list ap)339 hook_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