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: releng/11.0/sbin/hastd/hooks.c 298876 2016-05-01 08:22:11Z ed $");
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 <paths.h>
41#include <signal.h>
42#include <stdbool.h>
43#include <stdint.h>
44#include <stdio.h>
45#include <stdlib.h>
46#include <string.h>
47#include <syslog.h>
48#include <unistd.h>
49
50#include <pjdlog.h>
51
52#include "hooks.h"
53#include "subr.h"
54#include "synch.h"
55
56/* Report processes that are running for too long not often than this value. */
57#define	REPORT_INTERVAL	60
58
59/* Are we initialized? */
60static bool hooks_initialized = false;
61
62/*
63 * Keep all processes we forked on a global queue, so we can report nicely
64 * when they finish or report that they are running for a long time.
65 */
66#define	HOOKPROC_MAGIC_ALLOCATED	0x80090ca
67#define	HOOKPROC_MAGIC_ONLIST		0x80090c0
68struct hookproc {
69	/* Magic. */
70	int	hp_magic;
71	/* PID of a forked child. */
72	pid_t	hp_pid;
73	/* When process were forked? */
74	time_t	hp_birthtime;
75	/* When we logged previous reported? */
76	time_t	hp_lastreport;
77	/* Path to executable and all the arguments we passed. */
78	char	hp_comm[PATH_MAX];
79	TAILQ_ENTRY(hookproc) hp_next;
80};
81static TAILQ_HEAD(, hookproc) hookprocs;
82static pthread_mutex_t hookprocs_lock;
83
84static void hook_remove(struct hookproc *hp);
85static void hook_free(struct hookproc *hp);
86
87static void
88descriptors(void)
89{
90	int fd;
91
92	/*
93	 * Close all (or almost all) descriptors.
94	 */
95	if (pjdlog_mode_get() == PJDLOG_MODE_STD) {
96		closefrom(MAX(MAX(STDIN_FILENO, STDOUT_FILENO),
97		    STDERR_FILENO) + 1);
98		return;
99	}
100
101	closefrom(0);
102
103	/*
104	 * Redirect stdin, stdout and stderr to /dev/null.
105	 */
106	fd = open(_PATH_DEVNULL, O_RDONLY);
107	if (fd == -1) {
108		pjdlog_errno(LOG_WARNING, "Unable to open %s for reading",
109		    _PATH_DEVNULL);
110	} else if (fd != STDIN_FILENO) {
111		if (dup2(fd, STDIN_FILENO) == -1) {
112			pjdlog_errno(LOG_WARNING,
113			    "Unable to duplicate descriptor for stdin");
114		}
115		close(fd);
116	}
117	fd = open(_PATH_DEVNULL, O_WRONLY);
118	if (fd == -1) {
119		pjdlog_errno(LOG_WARNING, "Unable to open %s for writing",
120		    _PATH_DEVNULL);
121	} else {
122		if (fd != STDOUT_FILENO && dup2(fd, STDOUT_FILENO) == -1) {
123			pjdlog_errno(LOG_WARNING,
124			    "Unable to duplicate descriptor for stdout");
125		}
126		if (fd != STDERR_FILENO && dup2(fd, STDERR_FILENO) == -1) {
127			pjdlog_errno(LOG_WARNING,
128			    "Unable to duplicate descriptor for stderr");
129		}
130		if (fd != STDOUT_FILENO && fd != STDERR_FILENO)
131			close(fd);
132	}
133}
134
135void
136hook_init(void)
137{
138
139	PJDLOG_ASSERT(!hooks_initialized);
140
141	mtx_init(&hookprocs_lock);
142	TAILQ_INIT(&hookprocs);
143	hooks_initialized = true;
144}
145
146void
147hook_fini(void)
148{
149	struct hookproc *hp;
150
151	PJDLOG_ASSERT(hooks_initialized);
152
153	mtx_lock(&hookprocs_lock);
154	while ((hp = TAILQ_FIRST(&hookprocs)) != NULL) {
155		PJDLOG_ASSERT(hp->hp_magic == HOOKPROC_MAGIC_ONLIST);
156		PJDLOG_ASSERT(hp->hp_pid > 0);
157
158		hook_remove(hp);
159		hook_free(hp);
160	}
161	mtx_unlock(&hookprocs_lock);
162
163	mtx_destroy(&hookprocs_lock);
164	TAILQ_INIT(&hookprocs);
165	hooks_initialized = false;
166}
167
168static struct hookproc *
169hook_alloc(const char *path, char **args)
170{
171	struct hookproc *hp;
172	unsigned int ii;
173
174	hp = malloc(sizeof(*hp));
175	if (hp == NULL) {
176		pjdlog_error("Unable to allocate %zu bytes of memory for a hook.",
177		    sizeof(*hp));
178		return (NULL);
179	}
180
181	hp->hp_pid = 0;
182	hp->hp_birthtime = hp->hp_lastreport = time(NULL);
183	(void)strlcpy(hp->hp_comm, path, sizeof(hp->hp_comm));
184	/* We start at 2nd argument as we don't want to have exec name twice. */
185	for (ii = 1; args[ii] != NULL; ii++) {
186		(void)snprlcat(hp->hp_comm, sizeof(hp->hp_comm), " %s",
187		    args[ii]);
188	}
189	if (strlen(hp->hp_comm) >= sizeof(hp->hp_comm) - 1) {
190		pjdlog_error("Exec path too long, correct configuration file.");
191		free(hp);
192		return (NULL);
193	}
194	hp->hp_magic = HOOKPROC_MAGIC_ALLOCATED;
195	return (hp);
196}
197
198static void
199hook_add(struct hookproc *hp, pid_t pid)
200{
201
202	PJDLOG_ASSERT(hp->hp_magic == HOOKPROC_MAGIC_ALLOCATED);
203	PJDLOG_ASSERT(hp->hp_pid == 0);
204
205	hp->hp_pid = pid;
206	mtx_lock(&hookprocs_lock);
207	hp->hp_magic = HOOKPROC_MAGIC_ONLIST;
208	TAILQ_INSERT_TAIL(&hookprocs, hp, hp_next);
209	mtx_unlock(&hookprocs_lock);
210}
211
212static void
213hook_remove(struct hookproc *hp)
214{
215
216	PJDLOG_ASSERT(hp->hp_magic == HOOKPROC_MAGIC_ONLIST);
217	PJDLOG_ASSERT(hp->hp_pid > 0);
218	PJDLOG_ASSERT(mtx_owned(&hookprocs_lock));
219
220	TAILQ_REMOVE(&hookprocs, hp, hp_next);
221	hp->hp_magic = HOOKPROC_MAGIC_ALLOCATED;
222}
223
224static void
225hook_free(struct hookproc *hp)
226{
227
228	PJDLOG_ASSERT(hp->hp_magic == HOOKPROC_MAGIC_ALLOCATED);
229	PJDLOG_ASSERT(hp->hp_pid > 0);
230
231	hp->hp_magic = 0;
232	free(hp);
233}
234
235static struct hookproc *
236hook_find(pid_t pid)
237{
238	struct hookproc *hp;
239
240	PJDLOG_ASSERT(mtx_owned(&hookprocs_lock));
241
242	TAILQ_FOREACH(hp, &hookprocs, hp_next) {
243		PJDLOG_ASSERT(hp->hp_magic == HOOKPROC_MAGIC_ONLIST);
244		PJDLOG_ASSERT(hp->hp_pid > 0);
245
246		if (hp->hp_pid == pid)
247			break;
248	}
249
250	return (hp);
251}
252
253void
254hook_check_one(pid_t pid, int status)
255{
256	struct hookproc *hp;
257
258	mtx_lock(&hookprocs_lock);
259	hp = hook_find(pid);
260	if (hp == NULL) {
261		mtx_unlock(&hookprocs_lock);
262		pjdlog_debug(1, "Unknown process pid=%u", pid);
263		return;
264	}
265	hook_remove(hp);
266	mtx_unlock(&hookprocs_lock);
267	if (WIFEXITED(status) && WEXITSTATUS(status) == 0) {
268		pjdlog_debug(1, "Hook exited gracefully (pid=%u, cmd=[%s]).",
269		    pid, hp->hp_comm);
270	} else if (WIFSIGNALED(status)) {
271		pjdlog_error("Hook was killed (pid=%u, signal=%d, cmd=[%s]).",
272		    pid, WTERMSIG(status), hp->hp_comm);
273	} else {
274		pjdlog_error("Hook exited ungracefully (pid=%u, exitcode=%d, cmd=[%s]).",
275		    pid, WIFEXITED(status) ? WEXITSTATUS(status) : -1,
276		    hp->hp_comm);
277	}
278	hook_free(hp);
279}
280
281void
282hook_check(void)
283{
284	struct hookproc *hp, *hp2;
285	time_t now;
286
287	PJDLOG_ASSERT(hooks_initialized);
288
289	pjdlog_debug(2, "Checking hooks.");
290
291	/*
292	 * Report about processes that are running for a long time.
293	 */
294	now = time(NULL);
295	mtx_lock(&hookprocs_lock);
296	TAILQ_FOREACH_SAFE(hp, &hookprocs, hp_next, hp2) {
297		PJDLOG_ASSERT(hp->hp_magic == HOOKPROC_MAGIC_ONLIST);
298		PJDLOG_ASSERT(hp->hp_pid > 0);
299
300		/*
301		 * If process doesn't exists we somehow missed it.
302		 * Not much can be done expect for logging this situation.
303		 */
304		if (kill(hp->hp_pid, 0) == -1 && errno == ESRCH) {
305			pjdlog_warning("Hook disappeared (pid=%u, cmd=[%s]).",
306			    hp->hp_pid, hp->hp_comm);
307			hook_remove(hp);
308			hook_free(hp);
309			continue;
310		}
311
312		/*
313		 * Skip proccesses younger than 1 minute.
314		 */
315		if (now - hp->hp_lastreport < REPORT_INTERVAL)
316			continue;
317
318		/*
319		 * Hook is running for too long, report it.
320		 */
321		pjdlog_warning("Hook is running for %ju seconds (pid=%u, cmd=[%s]).",
322		    (uintmax_t)(now - hp->hp_birthtime), hp->hp_pid,
323		    hp->hp_comm);
324		hp->hp_lastreport = now;
325	}
326	mtx_unlock(&hookprocs_lock);
327}
328
329void
330hook_exec(const char *path, ...)
331{
332	va_list ap;
333
334	va_start(ap, path);
335	hook_execv(path, ap);
336	va_end(ap);
337}
338
339void
340hook_execv(const char *path, va_list ap)
341{
342	struct hookproc *hp;
343	char *args[64];
344	unsigned int ii;
345	sigset_t mask;
346	pid_t pid;
347
348	PJDLOG_ASSERT(hooks_initialized);
349
350	if (path == NULL || path[0] == '\0')
351		return;
352
353	memset(args, 0, sizeof(args));
354	args[0] = __DECONST(char *, path);
355	for (ii = 1; ii < sizeof(args) / sizeof(args[0]); ii++) {
356		args[ii] = va_arg(ap, char *);
357		if (args[ii] == NULL)
358			break;
359	}
360	PJDLOG_ASSERT(ii < sizeof(args) / sizeof(args[0]));
361
362	hp = hook_alloc(path, args);
363	if (hp == NULL)
364		return;
365
366	pjdlog_debug(1, "Executing hook: %s", hp->hp_comm);
367
368	pid = fork();
369	switch (pid) {
370	case -1:	/* Error. */
371		pjdlog_errno(LOG_ERR, "Unable to fork to execute %s", path);
372		hook_free(hp);
373		return;
374	case 0:		/* Child. */
375		descriptors();
376		PJDLOG_VERIFY(sigemptyset(&mask) == 0);
377		PJDLOG_VERIFY(sigprocmask(SIG_SETMASK, &mask, NULL) == 0);
378		/*
379		 * Dummy handler set for SIGCHLD in the parent will be restored
380		 * to SIG_IGN on execv(3) below, so there is no need to do
381		 * anything with it.
382		 */
383		execv(path, args);
384		pjdlog_errno(LOG_ERR, "Unable to execute %s", path);
385		exit(EX_SOFTWARE);
386	default:	/* Parent. */
387		hook_add(hp, pid);
388		break;
389	}
390}
391