1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 2005 Pawel Jakub Dawidek <pjd@FreeBSD.org>
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29 #include <sys/param.h>
30 #include <sys/types.h>
31 #include <sys/capsicum.h>
32 #include <sys/file.h>
33 #include <sys/stat.h>
34
35 #include <err.h>
36 #include <errno.h>
37 #include <fcntl.h>
38 #include <libgen.h>
39 #include <libutil.h>
40 #include <signal.h>
41 #include <stdio.h>
42 #include <stdlib.h>
43 #include <string.h>
44 #include <time.h>
45 #include <unistd.h>
46
47 struct pidfh {
48 int pf_dirfd;
49 int pf_fd;
50 char pf_dir[MAXPATHLEN + 1];
51 char pf_filename[MAXPATHLEN + 1];
52 dev_t pf_dev;
53 ino_t pf_ino;
54 };
55
56 static int _pidfile_remove(struct pidfh *pfh, int freeit);
57
58 static int
pidfile_verify(const struct pidfh * pfh)59 pidfile_verify(const struct pidfh *pfh)
60 {
61 struct stat sb;
62
63 if (pfh == NULL || pfh->pf_fd == -1)
64 return (EDOOFUS);
65 /*
66 * Check remembered descriptor.
67 */
68 if (fstat(pfh->pf_fd, &sb) == -1)
69 return (errno);
70 if (sb.st_dev != pfh->pf_dev || sb.st_ino != pfh->pf_ino)
71 return (EDOOFUS);
72 return (0);
73 }
74
75 static int
pidfile_read_impl(int dirfd,const char * filename,pid_t * pidptr)76 pidfile_read_impl(int dirfd, const char *filename, pid_t *pidptr)
77 {
78 char buf[16], *endptr;
79 int error, fd, i;
80
81 fd = openat(dirfd, filename, O_RDONLY | O_CLOEXEC);
82 if (fd == -1)
83 return (errno);
84
85 i = read(fd, buf, sizeof(buf) - 1);
86 error = errno; /* Remember errno in case close() wants to change it. */
87 close(fd);
88 if (i == -1)
89 return (error);
90 else if (i == 0)
91 return (EAGAIN);
92 buf[i] = '\0';
93
94 *pidptr = strtol(buf, &endptr, 10);
95 if (endptr != &buf[i])
96 return (EINVAL);
97
98 return (0);
99 }
100
101 static int
pidfile_read(int dirfd,const char * filename,pid_t * pidptr)102 pidfile_read(int dirfd, const char *filename, pid_t *pidptr)
103 {
104 struct timespec rqtp;
105 int count;
106
107 count = 20;
108 rqtp.tv_sec = 0;
109 rqtp.tv_nsec = 5000000;
110 for (;;) {
111 errno = pidfile_read_impl(dirfd, filename, pidptr);
112 if (errno != EAGAIN || --count == 0)
113 break;
114 nanosleep(&rqtp, 0);
115 }
116 if (errno == EAGAIN)
117 *pidptr = -1;
118 return (errno);
119 }
120
121 struct pidfh *
pidfile_open(const char * pathp,mode_t mode,pid_t * pidptr)122 pidfile_open(const char *pathp, mode_t mode, pid_t *pidptr)
123 {
124 char path[MAXPATHLEN];
125 struct pidfh *pfh;
126 struct stat sb;
127 int error, fd, dirfd, dirlen, filenamelen;
128 cap_rights_t caprights;
129
130 pfh = malloc(sizeof(*pfh));
131 if (pfh == NULL)
132 return (NULL);
133
134 if (pathp == NULL) {
135 dirlen = snprintf(pfh->pf_dir, sizeof(pfh->pf_dir),
136 "/var/run/");
137 filenamelen = snprintf(pfh->pf_filename,
138 sizeof(pfh->pf_filename), "%s.pid", getprogname());
139 } else {
140 if (strlcpy(path, pathp, sizeof(path)) >= sizeof(path)) {
141 free(pfh);
142 errno = ENAMETOOLONG;
143 return (NULL);
144 }
145 dirlen = strlcpy(pfh->pf_dir, dirname(path),
146 sizeof(pfh->pf_dir));
147 (void)strlcpy(path, pathp, sizeof(path));
148 filenamelen = strlcpy(pfh->pf_filename, basename(path),
149 sizeof(pfh->pf_filename));
150 }
151
152 if (dirlen >= (int)sizeof(pfh->pf_dir) ||
153 filenamelen >= (int)sizeof(pfh->pf_filename)) {
154 free(pfh);
155 errno = ENAMETOOLONG;
156 return (NULL);
157 }
158
159 dirfd = open(pfh->pf_dir, O_CLOEXEC | O_DIRECTORY | O_NONBLOCK);
160 if (dirfd == -1) {
161 error = errno;
162 free(pfh);
163 errno = error;
164 return (NULL);
165 }
166
167 /*
168 * Open the PID file and obtain exclusive lock.
169 * We truncate PID file here only to remove old PID immediately,
170 * PID file will be truncated again in pidfile_write(), so
171 * pidfile_write() can be called multiple times.
172 */
173 fd = flopenat(dirfd, pfh->pf_filename,
174 O_WRONLY | O_CREAT | O_TRUNC | O_CLOEXEC | O_NONBLOCK, mode);
175 if (fd == -1) {
176 if (errno == EWOULDBLOCK) {
177 if (pidptr == NULL) {
178 errno = EEXIST;
179 } else {
180 errno = pidfile_read(dirfd,
181 pfh->pf_filename, pidptr);
182 if (errno == 0 || errno == EAGAIN)
183 errno = EEXIST;
184 }
185 }
186 error = errno;
187 close(dirfd);
188 free(pfh);
189 errno = error;
190 return (NULL);
191 }
192
193 /*
194 * Remember file information, so in pidfile_write() we are sure we write
195 * to the proper descriptor.
196 */
197 if (fstat(fd, &sb) == -1) {
198 goto failed;
199 }
200
201 if (cap_rights_limit(dirfd,
202 cap_rights_init(&caprights, CAP_UNLINKAT)) < 0 && errno != ENOSYS) {
203 goto failed;
204 }
205
206 if (cap_rights_limit(fd, cap_rights_init(&caprights, CAP_PWRITE,
207 CAP_FSTAT, CAP_FTRUNCATE, CAP_EVENT)) < 0 &&
208 errno != ENOSYS) {
209 goto failed;
210 }
211
212 pfh->pf_dirfd = dirfd;
213 pfh->pf_fd = fd;
214 pfh->pf_dev = sb.st_dev;
215 pfh->pf_ino = sb.st_ino;
216
217 return (pfh);
218
219 failed:
220 error = errno;
221 unlinkat(dirfd, pfh->pf_filename, 0);
222 close(dirfd);
223 close(fd);
224 free(pfh);
225 errno = error;
226 return (NULL);
227 }
228
229 int
pidfile_write(struct pidfh * pfh)230 pidfile_write(struct pidfh *pfh)
231 {
232 char pidstr[16];
233 int error, fd;
234
235 /*
236 * Check remembered descriptor, so we don't overwrite some other
237 * file if pidfile was closed and descriptor reused.
238 */
239 errno = pidfile_verify(pfh);
240 if (errno != 0) {
241 /*
242 * Don't close descriptor, because we are not sure if it's ours.
243 */
244 return (-1);
245 }
246 fd = pfh->pf_fd;
247
248 /*
249 * Truncate PID file, so multiple calls of pidfile_write() are allowed.
250 */
251 if (ftruncate(fd, 0) == -1) {
252 error = errno;
253 _pidfile_remove(pfh, 0);
254 errno = error;
255 return (-1);
256 }
257
258 snprintf(pidstr, sizeof(pidstr), "%u", getpid());
259 if (pwrite(fd, pidstr, strlen(pidstr), 0) != (ssize_t)strlen(pidstr)) {
260 error = errno;
261 _pidfile_remove(pfh, 0);
262 errno = error;
263 return (-1);
264 }
265
266 return (0);
267 }
268
269 int
pidfile_close(struct pidfh * pfh)270 pidfile_close(struct pidfh *pfh)
271 {
272 int error;
273
274 error = pidfile_verify(pfh);
275 if (error != 0) {
276 errno = error;
277 return (-1);
278 }
279
280 if (close(pfh->pf_fd) == -1)
281 error = errno;
282 if (close(pfh->pf_dirfd) == -1 && error == 0)
283 error = errno;
284
285 free(pfh);
286 if (error != 0) {
287 errno = error;
288 return (-1);
289 }
290 return (0);
291 }
292
293 static int
_pidfile_remove(struct pidfh * pfh,int freeit)294 _pidfile_remove(struct pidfh *pfh, int freeit)
295 {
296 int error;
297
298 error = pidfile_verify(pfh);
299 if (error != 0) {
300 errno = error;
301 return (-1);
302 }
303
304 if (funlinkat(pfh->pf_dirfd, pfh->pf_filename, pfh->pf_fd, 0) == -1) {
305 if (errno == EDEADLK)
306 return (-1);
307 error = errno;
308 }
309 if (close(pfh->pf_fd) == -1 && error == 0)
310 error = errno;
311 if (close(pfh->pf_dirfd) == -1 && error == 0)
312 error = errno;
313 if (freeit)
314 free(pfh);
315 else
316 pfh->pf_fd = -1;
317 if (error != 0) {
318 errno = error;
319 return (-1);
320 }
321 return (0);
322 }
323
324 int
pidfile_remove(struct pidfh * pfh)325 pidfile_remove(struct pidfh *pfh)
326 {
327
328 return (_pidfile_remove(pfh, 1));
329 }
330
331 int
pidfile_fileno(const struct pidfh * pfh)332 pidfile_fileno(const struct pidfh *pfh)
333 {
334
335 if (pfh == NULL || pfh->pf_fd == -1) {
336 errno = EDOOFUS;
337 return (-1);
338 }
339 return (pfh->pf_fd);
340 }
341
342 int
pidfile_signal(const char * pathp,int sig,pid_t * pidptr)343 pidfile_signal(const char *pathp, int sig, pid_t *pidptr)
344 {
345 pid_t pid;
346 int fd;
347
348 fd = flopenat(AT_FDCWD, pathp,
349 O_RDONLY | O_CLOEXEC | O_NONBLOCK);
350 if (fd >= 0) {
351 /*
352 * The file exists but is not locked,
353 * so the daemon is dead. Nothing to do.
354 */
355 close(fd);
356 errno = ENOENT;
357 return (errno);
358 }
359 if (errno != EWOULDBLOCK) {
360 return (errno);
361 }
362 errno = pidfile_read(AT_FDCWD, pathp, &pid);
363 if (errno != 0)
364 return (errno);
365 /*
366 * Refuse to send broadcast or group signals, this has
367 * happened due to the bugs in pidfile(3).
368 */
369 if (pid <= 0)
370 return (EDOM);
371 kill(pid, sig);
372 if (pidptr != NULL)
373 *pidptr = pid;
374 return (errno);
375 }
376