1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 2005 Pawel Jakub Dawidek <[email protected]>
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/cdefs.h>
30 #include <sys/param.h>
31 #include <sys/types.h>
32 #include <sys/capsicum.h>
33 #include <sys/file.h>
34 #include <sys/stat.h>
35
36 #include <err.h>
37 #include <errno.h>
38 #include <fcntl.h>
39 #include <libgen.h>
40 #include <libutil.h>
41 #include <signal.h>
42 #include <stdio.h>
43 #include <stdlib.h>
44 #include <string.h>
45 #include <time.h>
46 #include <unistd.h>
47
48 struct pidfh {
49 int pf_dirfd;
50 int pf_fd;
51 char pf_dir[MAXPATHLEN + 1];
52 char pf_filename[MAXPATHLEN + 1];
53 dev_t pf_dev;
54 ino_t pf_ino;
55 };
56
57 static int _pidfile_remove(struct pidfh *pfh, int freeit);
58
59 static int
pidfile_verify(const struct pidfh * pfh)60 pidfile_verify(const struct pidfh *pfh)
61 {
62 struct stat sb;
63
64 if (pfh == NULL || pfh->pf_fd == -1)
65 return (EDOOFUS);
66 /*
67 * Check remembered descriptor.
68 */
69 if (fstat(pfh->pf_fd, &sb) == -1)
70 return (errno);
71 if (sb.st_dev != pfh->pf_dev || sb.st_ino != pfh->pf_ino)
72 return (EDOOFUS);
73 return (0);
74 }
75
76 static int
pidfile_read_impl(int dirfd,const char * filename,pid_t * pidptr)77 pidfile_read_impl(int dirfd, const char *filename, pid_t *pidptr)
78 {
79 char buf[16], *endptr;
80 int error, fd, i;
81
82 fd = openat(dirfd, filename, O_RDONLY | O_CLOEXEC);
83 if (fd == -1)
84 return (errno);
85
86 i = read(fd, buf, sizeof(buf) - 1);
87 error = errno; /* Remember errno in case close() wants to change it. */
88 close(fd);
89 if (i == -1)
90 return (error);
91 else if (i == 0)
92 return (EAGAIN);
93 buf[i] = '\0';
94
95 *pidptr = strtol(buf, &endptr, 10);
96 if (endptr != &buf[i])
97 return (EINVAL);
98
99 return (0);
100 }
101
102 static int
pidfile_read(int dirfd,const char * filename,pid_t * pidptr)103 pidfile_read(int dirfd, const char *filename, pid_t *pidptr)
104 {
105 struct timespec rqtp;
106 int count;
107
108 count = 20;
109 rqtp.tv_sec = 0;
110 rqtp.tv_nsec = 5000000;
111 for (;;) {
112 errno = pidfile_read_impl(dirfd, filename, pidptr);
113 if (errno != EAGAIN || --count == 0)
114 break;
115 nanosleep(&rqtp, 0);
116 }
117 if (errno == EAGAIN)
118 *pidptr = -1;
119 return (errno);
120 }
121
122 struct pidfh *
pidfile_open(const char * pathp,mode_t mode,pid_t * pidptr)123 pidfile_open(const char *pathp, mode_t mode, pid_t *pidptr)
124 {
125 char path[MAXPATHLEN];
126 struct pidfh *pfh;
127 struct stat sb;
128 int error, fd, dirfd, dirlen, filenamelen;
129 cap_rights_t caprights;
130
131 pfh = malloc(sizeof(*pfh));
132 if (pfh == NULL)
133 return (NULL);
134
135 if (pathp == NULL) {
136 dirlen = snprintf(pfh->pf_dir, sizeof(pfh->pf_dir),
137 "/var/run/");
138 filenamelen = snprintf(pfh->pf_filename,
139 sizeof(pfh->pf_filename), "%s.pid", getprogname());
140 } else {
141 if (strlcpy(path, pathp, sizeof(path)) >= sizeof(path)) {
142 free(pfh);
143 errno = ENAMETOOLONG;
144 return (NULL);
145 }
146 dirlen = strlcpy(pfh->pf_dir, dirname(path),
147 sizeof(pfh->pf_dir));
148 (void)strlcpy(path, pathp, sizeof(path));
149 filenamelen = strlcpy(pfh->pf_filename, basename(path),
150 sizeof(pfh->pf_filename));
151 }
152
153 if (dirlen >= (int)sizeof(pfh->pf_dir) ||
154 filenamelen >= (int)sizeof(pfh->pf_filename)) {
155 free(pfh);
156 errno = ENAMETOOLONG;
157 return (NULL);
158 }
159
160 dirfd = open(pfh->pf_dir, O_CLOEXEC | O_DIRECTORY | O_NONBLOCK);
161 if (dirfd == -1) {
162 error = errno;
163 free(pfh);
164 errno = error;
165 return (NULL);
166 }
167
168 /*
169 * Open the PID file and obtain exclusive lock.
170 * We truncate PID file here only to remove old PID immediately,
171 * PID file will be truncated again in pidfile_write(), so
172 * pidfile_write() can be called multiple times.
173 */
174 fd = flopenat(dirfd, pfh->pf_filename,
175 O_WRONLY | O_CREAT | O_TRUNC | O_CLOEXEC | O_NONBLOCK, mode);
176 if (fd == -1) {
177 if (errno == EWOULDBLOCK) {
178 if (pidptr == NULL) {
179 errno = EEXIST;
180 } else {
181 errno = pidfile_read(dirfd,
182 pfh->pf_filename, pidptr);
183 if (errno == 0 || errno == EAGAIN)
184 errno = EEXIST;
185 }
186 }
187 error = errno;
188 close(dirfd);
189 free(pfh);
190 errno = error;
191 return (NULL);
192 }
193
194 /*
195 * Remember file information, so in pidfile_write() we are sure we write
196 * to the proper descriptor.
197 */
198 if (fstat(fd, &sb) == -1) {
199 goto failed;
200 }
201
202 if (cap_rights_limit(dirfd,
203 cap_rights_init(&caprights, CAP_UNLINKAT)) < 0 && errno != ENOSYS) {
204 goto failed;
205 }
206
207 if (cap_rights_limit(fd, cap_rights_init(&caprights, CAP_PWRITE,
208 CAP_FSTAT, CAP_FTRUNCATE, CAP_EVENT)) < 0 &&
209 errno != ENOSYS) {
210 goto failed;
211 }
212
213 pfh->pf_dirfd = dirfd;
214 pfh->pf_fd = fd;
215 pfh->pf_dev = sb.st_dev;
216 pfh->pf_ino = sb.st_ino;
217
218 return (pfh);
219
220 failed:
221 error = errno;
222 unlinkat(dirfd, pfh->pf_filename, 0);
223 close(dirfd);
224 close(fd);
225 free(pfh);
226 errno = error;
227 return (NULL);
228 }
229
230 int
pidfile_write(struct pidfh * pfh)231 pidfile_write(struct pidfh *pfh)
232 {
233 char pidstr[16];
234 int error, fd;
235
236 /*
237 * Check remembered descriptor, so we don't overwrite some other
238 * file if pidfile was closed and descriptor reused.
239 */
240 errno = pidfile_verify(pfh);
241 if (errno != 0) {
242 /*
243 * Don't close descriptor, because we are not sure if it's ours.
244 */
245 return (-1);
246 }
247 fd = pfh->pf_fd;
248
249 /*
250 * Truncate PID file, so multiple calls of pidfile_write() are allowed.
251 */
252 if (ftruncate(fd, 0) == -1) {
253 error = errno;
254 _pidfile_remove(pfh, 0);
255 errno = error;
256 return (-1);
257 }
258
259 snprintf(pidstr, sizeof(pidstr), "%u", getpid());
260 if (pwrite(fd, pidstr, strlen(pidstr), 0) != (ssize_t)strlen(pidstr)) {
261 error = errno;
262 _pidfile_remove(pfh, 0);
263 errno = error;
264 return (-1);
265 }
266
267 return (0);
268 }
269
270 int
pidfile_close(struct pidfh * pfh)271 pidfile_close(struct pidfh *pfh)
272 {
273 int error;
274
275 error = pidfile_verify(pfh);
276 if (error != 0) {
277 errno = error;
278 return (-1);
279 }
280
281 if (close(pfh->pf_fd) == -1)
282 error = errno;
283 if (close(pfh->pf_dirfd) == -1 && error == 0)
284 error = errno;
285
286 free(pfh);
287 if (error != 0) {
288 errno = error;
289 return (-1);
290 }
291 return (0);
292 }
293
294 static int
_pidfile_remove(struct pidfh * pfh,int freeit)295 _pidfile_remove(struct pidfh *pfh, int freeit)
296 {
297 int error;
298
299 error = pidfile_verify(pfh);
300 if (error != 0) {
301 errno = error;
302 return (-1);
303 }
304
305 if (funlinkat(pfh->pf_dirfd, pfh->pf_filename, pfh->pf_fd, 0) == -1) {
306 if (errno == EDEADLK)
307 return (-1);
308 error = errno;
309 }
310 if (close(pfh->pf_fd) == -1 && error == 0)
311 error = errno;
312 if (close(pfh->pf_dirfd) == -1 && error == 0)
313 error = errno;
314 if (freeit)
315 free(pfh);
316 else
317 pfh->pf_fd = -1;
318 if (error != 0) {
319 errno = error;
320 return (-1);
321 }
322 return (0);
323 }
324
325 int
pidfile_remove(struct pidfh * pfh)326 pidfile_remove(struct pidfh *pfh)
327 {
328
329 return (_pidfile_remove(pfh, 1));
330 }
331
332 int
pidfile_fileno(const struct pidfh * pfh)333 pidfile_fileno(const struct pidfh *pfh)
334 {
335
336 if (pfh == NULL || pfh->pf_fd == -1) {
337 errno = EDOOFUS;
338 return (-1);
339 }
340 return (pfh->pf_fd);
341 }
342
343 int
pidfile_signal(const char * pathp,int sig,pid_t * pidptr)344 pidfile_signal(const char *pathp, int sig, pid_t *pidptr)
345 {
346 pid_t pid;
347 int fd;
348
349 fd = flopenat(AT_FDCWD, pathp,
350 O_RDONLY | O_CLOEXEC | O_NONBLOCK);
351 if (fd >= 0) {
352 /*
353 * The file exists but is not locked,
354 * so the daemon is dead. Nothing to do.
355 */
356 close(fd);
357 errno = ENOENT;
358 return (errno);
359 }
360 if (errno != EWOULDBLOCK) {
361 return (errno);
362 }
363 errno = pidfile_read(AT_FDCWD, pathp, &pid);
364 if (errno != 0)
365 return (errno);
366 /*
367 * Refuse to send broadcast or group signals, this has
368 * happened due to the bugs in pidfile(3).
369 */
370 if (pid <= 0)
371 return (EDOM);
372 kill(pid, sig);
373 if (pidptr != NULL)
374 *pidptr = pid;
375 return (errno);
376 }
377