1 /*- 2 * SPDX-License-Identifier: BSD-3-Clause 3 * 4 * Copyright (c) 1999 Berkeley Software Design, Inc. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 3. Berkeley Software Design Inc's name may not be used to endorse or 15 * promote products derived from this software without specific prior 16 * written permission. 17 * 18 * THIS SOFTWARE IS PROVIDED BY BERKELEY SOFTWARE DESIGN INC ``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 BERKELEY SOFTWARE DESIGN INC 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 * From BSDI: daemon.c,v 1.2 1996/08/15 01:11:09 jch Exp 31 */ 32 33 #include <sys/cdefs.h> 34 __FBSDID("$FreeBSD$"); 35 36 #include <sys/param.h> 37 #include <sys/mman.h> 38 #include <sys/wait.h> 39 40 #include <fcntl.h> 41 #include <err.h> 42 #include <errno.h> 43 #include <libutil.h> 44 #include <login_cap.h> 45 #include <pwd.h> 46 #include <signal.h> 47 #include <stdio.h> 48 #include <stdlib.h> 49 #include <unistd.h> 50 #include <string.h> 51 #include <strings.h> 52 #define SYSLOG_NAMES 53 #include <syslog.h> 54 #include <time.h> 55 #include <assert.h> 56 57 #define LBUF_SIZE 4096 58 59 struct log_params { 60 int dosyslog; 61 int logpri; 62 int noclose; 63 int outfd; 64 }; 65 66 static void restrict_process(const char *); 67 static void handle_term(int); 68 static void handle_chld(int); 69 static int listen_child(int, struct log_params *); 70 static int get_log_mapping(const char *, const CODE *); 71 static void open_pid_files(const char *, const char *, struct pidfh **, 72 struct pidfh **); 73 static void do_output(const unsigned char *, size_t, struct log_params *); 74 static void daemon_sleep(time_t, long); 75 static void usage(void); 76 77 static volatile sig_atomic_t terminate = 0, child_gone = 0, pid = 0; 78 79 int 80 main(int argc, char *argv[]) 81 { 82 const char *pidfile, *ppidfile, *title, *user, *outfn, *logtag; 83 int ch, nochdir, noclose, restart, dosyslog, child_eof; 84 sigset_t mask_susp, mask_orig, mask_read, mask_term; 85 struct log_params logpar; 86 int pfd[2] = { -1, -1 }, outfd = -1; 87 int stdmask, logpri, logfac; 88 struct pidfh *ppfh, *pfh; 89 char *p; 90 91 memset(&logpar, 0, sizeof(logpar)); 92 stdmask = STDOUT_FILENO | STDERR_FILENO; 93 ppidfile = pidfile = user = NULL; 94 nochdir = noclose = 1; 95 logpri = LOG_NOTICE; 96 logfac = LOG_DAEMON; 97 logtag = "daemon"; 98 restart = 0; 99 dosyslog = 0; 100 outfn = NULL; 101 title = NULL; 102 while ((ch = getopt(argc, argv, "cfSp:P:ru:o:s:l:t:l:m:R:T:")) != -1) { 103 switch (ch) { 104 case 'c': 105 nochdir = 0; 106 break; 107 case 'f': 108 noclose = 0; 109 break; 110 case 'l': 111 logfac = get_log_mapping(optarg, facilitynames); 112 if (logfac == -1) 113 errx(5, "unrecognized syslog facility"); 114 dosyslog = 1; 115 break; 116 case 'm': 117 stdmask = strtol(optarg, &p, 10); 118 if (p == optarg || stdmask < 0 || stdmask > 3) 119 errx(6, "unrecognized listening mask"); 120 break; 121 case 'o': 122 outfn = optarg; 123 break; 124 case 'p': 125 pidfile = optarg; 126 break; 127 case 'P': 128 ppidfile = optarg; 129 break; 130 case 'r': 131 restart = 1; 132 break; 133 case 'R': 134 restart = strtol(optarg, &p, 0); 135 if (p == optarg || restart < 1) 136 errx(6, "invalid restart delay"); 137 break; 138 case 's': 139 logpri = get_log_mapping(optarg, prioritynames); 140 if (logpri == -1) 141 errx(4, "unrecognized syslog priority"); 142 dosyslog = 1; 143 break; 144 case 'S': 145 dosyslog = 1; 146 break; 147 case 't': 148 title = optarg; 149 break; 150 case 'T': 151 logtag = optarg; 152 dosyslog = 1; 153 break; 154 case 'u': 155 user = optarg; 156 break; 157 default: 158 usage(); 159 } 160 } 161 argc -= optind; 162 argv += optind; 163 164 if (argc == 0) 165 usage(); 166 167 if (!title) 168 title = argv[0]; 169 170 if (outfn) { 171 outfd = open(outfn, O_CREAT | O_WRONLY | O_APPEND | O_CLOEXEC, 0600); 172 if (outfd == -1) 173 err(7, "open"); 174 } 175 176 if (dosyslog) 177 openlog(logtag, LOG_PID | LOG_NDELAY, logfac); 178 179 ppfh = pfh = NULL; 180 /* 181 * Try to open the pidfile before calling daemon(3), 182 * to be able to report the error intelligently 183 */ 184 open_pid_files(pidfile, ppidfile, &pfh, &ppfh); 185 if (daemon(nochdir, noclose) == -1) { 186 warn("daemon"); 187 goto exit; 188 } 189 /* Write out parent pidfile if needed. */ 190 pidfile_write(ppfh); 191 /* 192 * If the pidfile or restart option is specified the daemon 193 * executes the command in a forked process and wait on child 194 * exit to remove the pidfile or restart the command. Normally 195 * we don't want the monitoring daemon to be terminated 196 * leaving the running process and the stale pidfile, so we 197 * catch SIGTERM and forward it to the children expecting to 198 * get SIGCHLD eventually. We also must fork() to obtain a 199 * readable pipe with the child for writing to a log file 200 * and syslog. 201 */ 202 pid = -1; 203 if (pidfile || ppidfile || restart || outfd != -1 || dosyslog) { 204 struct sigaction act_term, act_chld; 205 206 /* Avoid PID racing with SIGCHLD and SIGTERM. */ 207 memset(&act_term, 0, sizeof(act_term)); 208 act_term.sa_handler = handle_term; 209 sigemptyset(&act_term.sa_mask); 210 sigaddset(&act_term.sa_mask, SIGCHLD); 211 212 memset(&act_chld, 0, sizeof(act_chld)); 213 act_chld.sa_handler = handle_chld; 214 sigemptyset(&act_chld.sa_mask); 215 sigaddset(&act_chld.sa_mask, SIGTERM); 216 217 /* Block these when avoiding racing before sigsuspend(). */ 218 sigemptyset(&mask_susp); 219 sigaddset(&mask_susp, SIGTERM); 220 sigaddset(&mask_susp, SIGCHLD); 221 /* Block SIGTERM when we lack a valid child PID. */ 222 sigemptyset(&mask_term); 223 sigaddset(&mask_term, SIGTERM); 224 /* 225 * When reading, we wish to avoid SIGCHLD. SIGTERM 226 * has to be caught, otherwise we'll be stuck until 227 * the read() returns - if it returns. 228 */ 229 sigemptyset(&mask_read); 230 sigaddset(&mask_read, SIGCHLD); 231 /* Block SIGTERM to avoid racing until we have forked. */ 232 if (sigprocmask(SIG_BLOCK, &mask_term, &mask_orig)) { 233 warn("sigprocmask"); 234 goto exit; 235 } 236 if (sigaction(SIGTERM, &act_term, NULL) == -1) { 237 warn("sigaction"); 238 goto exit; 239 } 240 if (sigaction(SIGCHLD, &act_chld, NULL) == -1) { 241 warn("sigaction"); 242 goto exit; 243 } 244 /* 245 * Try to protect against pageout kill. Ignore the 246 * error, madvise(2) will fail only if a process does 247 * not have superuser privileges. 248 */ 249 (void)madvise(NULL, 0, MADV_PROTECT); 250 logpar.outfd = outfd; 251 logpar.dosyslog = dosyslog; 252 logpar.logpri = logpri; 253 logpar.noclose = noclose; 254 restart: 255 if (pipe(pfd)) 256 err(1, "pipe"); 257 /* 258 * Spawn a child to exec the command. 259 */ 260 child_gone = 0; 261 pid = fork(); 262 if (pid == -1) { 263 warn("fork"); 264 goto exit; 265 } else if (pid > 0) { 266 /* 267 * Unblock SIGTERM after we know we have a valid 268 * child PID to signal. 269 */ 270 if (sigprocmask(SIG_UNBLOCK, &mask_term, NULL)) { 271 warn("sigprocmask"); 272 goto exit; 273 } 274 close(pfd[1]); 275 pfd[1] = -1; 276 } 277 } 278 if (pid <= 0) { 279 /* Now that we are the child, write out the pid. */ 280 pidfile_write(pfh); 281 282 if (user != NULL) 283 restrict_process(user); 284 /* 285 * When forking, the child gets the original sigmask, 286 * and dup'd pipes. 287 */ 288 if (pid == 0) { 289 close(pfd[0]); 290 if (sigprocmask(SIG_SETMASK, &mask_orig, NULL)) 291 err(1, "sigprogmask"); 292 if (stdmask & STDERR_FILENO) { 293 if (dup2(pfd[1], STDERR_FILENO) == -1) 294 err(1, "dup2"); 295 } 296 if (stdmask & STDOUT_FILENO) { 297 if (dup2(pfd[1], STDOUT_FILENO) == -1) 298 err(1, "dup2"); 299 } 300 if (pfd[1] != STDERR_FILENO && 301 pfd[1] != STDOUT_FILENO) 302 close(pfd[1]); 303 } 304 execvp(argv[0], argv); 305 /* 306 * execvp() failed -- report the error. The child is 307 * now running, so the exit status doesn't matter. 308 */ 309 err(1, "%s", argv[0]); 310 } 311 setproctitle("%s[%d]", title, (int)pid); 312 /* 313 * As we have closed the write end of pipe for parent process, 314 * we might detect the child's exit by reading EOF. The child 315 * might have closed its stdout and stderr, so we must wait for 316 * the SIGCHLD to ensure that the process is actually gone. 317 */ 318 child_eof = 0; 319 for (;;) { 320 /* 321 * We block SIGCHLD when listening, but SIGTERM we accept 322 * so the read() won't block if we wish to depart. 323 * 324 * Upon receiving SIGTERM, we have several options after 325 * sending the SIGTERM to our child: 326 * - read until EOF 327 * - read until EOF but only for a while 328 * - bail immediately 329 * 330 * We go for the third, as otherwise we have no guarantee 331 * that we won't block indefinitely if the child refuses 332 * to depart. To handle the second option, a different 333 * approach would be needed (procctl()?) 334 */ 335 if (child_gone && child_eof) { 336 break; 337 } else if (terminate) { 338 goto exit; 339 } else if (!child_eof) { 340 if (sigprocmask(SIG_BLOCK, &mask_read, NULL)) { 341 warn("sigprocmask"); 342 goto exit; 343 } 344 child_eof = !listen_child(pfd[0], &logpar); 345 if (sigprocmask(SIG_UNBLOCK, &mask_read, NULL)) { 346 warn("sigprocmask"); 347 goto exit; 348 } 349 } else { 350 if (sigprocmask(SIG_BLOCK, &mask_susp, NULL)) { 351 warn("sigprocmask"); 352 goto exit; 353 } 354 while (!terminate && !child_gone) 355 sigsuspend(&mask_orig); 356 if (sigprocmask(SIG_UNBLOCK, &mask_susp, NULL)) { 357 warn("sigprocmask"); 358 goto exit; 359 } 360 } 361 } 362 if (sigprocmask(SIG_BLOCK, &mask_term, NULL)) { 363 warn("sigprocmask"); 364 goto exit; 365 } 366 if (restart && !terminate) { 367 daemon_sleep(restart, 0); 368 close(pfd[0]); 369 pfd[0] = -1; 370 goto restart; 371 } 372 exit: 373 close(outfd); 374 close(pfd[0]); 375 close(pfd[1]); 376 if (dosyslog) 377 closelog(); 378 pidfile_remove(pfh); 379 pidfile_remove(ppfh); 380 exit(1); /* If daemon(3) succeeded exit status does not matter. */ 381 } 382 383 static void 384 daemon_sleep(time_t secs, long nsecs) 385 { 386 struct timespec ts = { secs, nsecs }; 387 while (nanosleep(&ts, &ts) == -1) { 388 if (errno != EINTR) 389 err(1, "nanosleep"); 390 } 391 } 392 393 static void 394 open_pid_files(const char *pidfile, const char *ppidfile, 395 struct pidfh **pfh, struct pidfh **ppfh) 396 { 397 pid_t fpid; 398 int serrno; 399 400 if (pidfile) { 401 *pfh = pidfile_open(pidfile, 0600, &fpid); 402 if (*pfh == NULL) { 403 if (errno == EEXIST) { 404 errx(3, "process already running, pid: %d", 405 fpid); 406 } 407 err(2, "pidfile ``%s''", pidfile); 408 } 409 } 410 /* Do the same for the actual daemon process. */ 411 if (ppidfile) { 412 *ppfh = pidfile_open(ppidfile, 0600, &fpid); 413 if (*ppfh == NULL) { 414 serrno = errno; 415 pidfile_remove(*pfh); 416 errno = serrno; 417 if (errno == EEXIST) { 418 errx(3, "process already running, pid: %d", 419 fpid); 420 } 421 err(2, "ppidfile ``%s''", ppidfile); 422 } 423 } 424 } 425 426 static int 427 get_log_mapping(const char *str, const CODE *c) 428 { 429 const CODE *cp; 430 for (cp = c; cp->c_name; cp++) 431 if (strcmp(cp->c_name, str) == 0) 432 return cp->c_val; 433 return -1; 434 } 435 436 static void 437 restrict_process(const char *user) 438 { 439 struct passwd *pw = NULL; 440 441 pw = getpwnam(user); 442 if (pw == NULL) 443 errx(1, "unknown user: %s", user); 444 445 if (setusercontext(NULL, pw, pw->pw_uid, LOGIN_SETALL) != 0) 446 errx(1, "failed to set user environment"); 447 } 448 449 /* 450 * We try to collect whole lines terminated by '\n'. Otherwise we collect a 451 * full buffer, and then output it. 452 * 453 * Return value of 0 is assumed to mean EOF or error, and 1 indicates to 454 * continue reading. 455 */ 456 static int 457 listen_child(int fd, struct log_params *logpar) 458 { 459 static unsigned char buf[LBUF_SIZE]; 460 static size_t bytes_read = 0; 461 int rv; 462 463 assert(logpar); 464 assert(bytes_read < LBUF_SIZE - 1); 465 466 rv = read(fd, buf + bytes_read, LBUF_SIZE - bytes_read - 1); 467 if (rv > 0) { 468 unsigned char *cp; 469 470 bytes_read += rv; 471 assert(bytes_read <= LBUF_SIZE - 1); 472 /* Always NUL-terminate just in case. */ 473 buf[LBUF_SIZE - 1] = '\0'; 474 /* 475 * Chomp line by line until we run out of buffer. 476 * This does not take NUL characters into account. 477 */ 478 while ((cp = memchr(buf, '\n', bytes_read)) != NULL) { 479 size_t bytes_line = cp - buf + 1; 480 assert(bytes_line <= bytes_read); 481 do_output(buf, bytes_line, logpar); 482 bytes_read -= bytes_line; 483 memmove(buf, cp + 1, bytes_read); 484 } 485 /* Wait until the buffer is full. */ 486 if (bytes_read < LBUF_SIZE - 1) 487 return 1; 488 do_output(buf, bytes_read, logpar); 489 bytes_read = 0; 490 return 1; 491 } else if (rv == -1) { 492 /* EINTR should trigger another read. */ 493 if (errno == EINTR) { 494 return 1; 495 } else { 496 warn("read"); 497 return 0; 498 } 499 } 500 /* Upon EOF, we have to flush what's left of the buffer. */ 501 if (bytes_read > 0) { 502 do_output(buf, bytes_read, logpar); 503 bytes_read = 0; 504 } 505 return 0; 506 } 507 508 /* 509 * The default behavior is to stay silent if the user wants to redirect 510 * output to a file and/or syslog. If neither are provided, then we bounce 511 * everything back to parent's stdout. 512 */ 513 static void 514 do_output(const unsigned char *buf, size_t len, struct log_params *logpar) 515 { 516 assert(len <= LBUF_SIZE); 517 assert(logpar); 518 519 if (len < 1) 520 return; 521 if (logpar->dosyslog) 522 syslog(logpar->logpri, "%.*s", (int)len, buf); 523 if (logpar->outfd != -1) { 524 if (write(logpar->outfd, buf, len) == -1) 525 warn("write"); 526 } 527 if (logpar->noclose && !logpar->dosyslog && logpar->outfd == -1) 528 printf("%.*s", (int)len, buf); 529 } 530 531 /* 532 * We use the global PID acquired directly from fork. If there is no valid 533 * child pid, the handler should be blocked and/or child_gone == 1. 534 */ 535 static void 536 handle_term(int signo) 537 { 538 if (pid > 0 && !child_gone) 539 kill(pid, signo); 540 terminate = 1; 541 } 542 543 static void 544 handle_chld(int signo) 545 { 546 (void)signo; 547 for (;;) { 548 int rv = waitpid(-1, NULL, WNOHANG); 549 if (pid == rv) { 550 child_gone = 1; 551 break; 552 } else if (rv == -1 && errno != EINTR) { 553 warn("waitpid"); 554 return; 555 } 556 } 557 } 558 559 static void 560 usage(void) 561 { 562 (void)fprintf(stderr, 563 "usage: daemon [-cfrS] [-p child_pidfile] [-P supervisor_pidfile]\n" 564 " [-u user] [-o output_file] [-t title]\n" 565 " [-l syslog_facility] [-s syslog_priority]\n" 566 " [-T syslog_tag] [-m output_mask] [-R restart_delay_secs]\n" 567 "command arguments ...\n"); 568 exit(1); 569 } 570