1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 2010 The FreeBSD Foundation
5 * Copyright (c) 2010 Pawel Jakub Dawidek <[email protected]>
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
descriptors(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
hook_init(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
hook_fini(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 *
hook_alloc(const char * path,char ** args)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
hook_add(struct hookproc * hp,pid_t pid)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
hook_remove(struct hookproc * hp)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
hook_free(struct hookproc * hp)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 *
hook_find(pid_t pid)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
hook_check_one(pid_t pid,int status)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
hook_check(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 proccesses 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
hook_exec(const char * path,...)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
hook_execv(const char * path,va_list ap)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