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: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 's': 134 logpri = get_log_mapping(optarg, prioritynames); 135 if (logpri == -1) 136 errx(4, "unrecognized syslog priority"); 137 dosyslog = 1; 138 break; 139 case 'S': 140 dosyslog = 1; 141 break; 142 case 't': 143 title = optarg; 144 break; 145 case 'T': 146 logtag = optarg; 147 dosyslog = 1; 148 break; 149 case 'u': 150 user = optarg; 151 break; 152 default: 153 usage(); 154 } 155 } 156 argc -= optind; 157 argv += optind; 158 159 if (argc == 0) 160 usage(); 161 162 if (!title) 163 title = argv[0]; 164 165 if (outfn) { 166 outfd = open(outfn, O_CREAT | O_WRONLY | O_APPEND | O_CLOEXEC, 0600); 167 if (outfd == -1) 168 err(7, "open"); 169 } 170 171 if (dosyslog) 172 openlog(logtag, LOG_PID | LOG_NDELAY, logfac); 173 174 ppfh = pfh = NULL; 175 /* 176 * Try to open the pidfile before calling daemon(3), 177 * to be able to report the error intelligently 178 */ 179 open_pid_files(pidfile, ppidfile, &pfh, &ppfh); 180 if (daemon(nochdir, noclose) == -1) { 181 warn("daemon"); 182 goto exit; 183 } 184 /* Write out parent pidfile if needed. */ 185 pidfile_write(ppfh); 186 /* 187 * If the pidfile or restart option is specified the daemon 188 * executes the command in a forked process and wait on child 189 * exit to remove the pidfile or restart the command. Normally 190 * we don't want the monitoring daemon to be terminated 191 * leaving the running process and the stale pidfile, so we 192 * catch SIGTERM and forward it to the children expecting to 193 * get SIGCHLD eventually. We also must fork() to obtain a 194 * readable pipe with the child for writing to a log file 195 * and syslog. 196 */ 197 pid = -1; 198 if (pidfile || ppidfile || restart || outfd != -1 || dosyslog) { 199 struct sigaction act_term, act_chld; 200 201 /* Avoid PID racing with SIGCHLD and SIGTERM. */ 202 memset(&act_term, 0, sizeof(act_term)); 203 act_term.sa_handler = handle_term; 204 sigemptyset(&act_term.sa_mask); 205 sigaddset(&act_term.sa_mask, SIGCHLD); 206 207 memset(&act_chld, 0, sizeof(act_chld)); 208 act_chld.sa_handler = handle_chld; 209 sigemptyset(&act_chld.sa_mask); 210 sigaddset(&act_chld.sa_mask, SIGTERM); 211 212 /* Block these when avoiding racing before sigsuspend(). */ 213 sigemptyset(&mask_susp); 214 sigaddset(&mask_susp, SIGTERM); 215 sigaddset(&mask_susp, SIGCHLD); 216 /* Block SIGTERM when we lack a valid child PID. */ 217 sigemptyset(&mask_term); 218 sigaddset(&mask_term, SIGTERM); 219 /* 220 * When reading, we wish to avoid SIGCHLD. SIGTERM 221 * has to be caught, otherwise we'll be stuck until 222 * the read() returns - if it returns. 223 */ 224 sigemptyset(&mask_read); 225 sigaddset(&mask_read, SIGCHLD); 226 /* Block SIGTERM to avoid racing until we have forked. */ 227 if (sigprocmask(SIG_BLOCK, &mask_term, &mask_orig)) { 228 warn("sigprocmask"); 229 goto exit; 230 } 231 if (sigaction(SIGTERM, &act_term, NULL) == -1) { 232 warn("sigaction"); 233 goto exit; 234 } 235 if (sigaction(SIGCHLD, &act_chld, NULL) == -1) { 236 warn("sigaction"); 237 goto exit; 238 } 239 /* 240 * Try to protect against pageout kill. Ignore the 241 * error, madvise(2) will fail only if a process does 242 * not have superuser privileges. 243 */ 244 (void)madvise(NULL, 0, MADV_PROTECT); 245 logpar.outfd = outfd; 246 logpar.dosyslog = dosyslog; 247 logpar.logpri = logpri; 248 logpar.noclose = noclose; 249 restart: 250 if (pipe(pfd)) 251 err(1, "pipe"); 252 /* 253 * Spawn a child to exec the command. 254 */ 255 child_gone = 0; 256 pid = fork(); 257 if (pid == -1) { 258 warn("fork"); 259 goto exit; 260 } else if (pid > 0) { 261 /* 262 * Unblock SIGTERM after we know we have a valid 263 * child PID to signal. 264 */ 265 if (sigprocmask(SIG_UNBLOCK, &mask_term, NULL)) { 266 warn("sigprocmask"); 267 goto exit; 268 } 269 close(pfd[1]); 270 pfd[1] = -1; 271 } 272 } 273 if (pid <= 0) { 274 /* Now that we are the child, write out the pid. */ 275 pidfile_write(pfh); 276 277 if (user != NULL) 278 restrict_process(user); 279 /* 280 * When forking, the child gets the original sigmask, 281 * and dup'd pipes. 282 */ 283 if (pid == 0) { 284 close(pfd[0]); 285 if (sigprocmask(SIG_SETMASK, &mask_orig, NULL)) 286 err(1, "sigprogmask"); 287 if (stdmask & STDERR_FILENO) { 288 if (dup2(pfd[1], STDERR_FILENO) == -1) 289 err(1, "dup2"); 290 } 291 if (stdmask & STDOUT_FILENO) { 292 if (dup2(pfd[1], STDOUT_FILENO) == -1) 293 err(1, "dup2"); 294 } 295 if (pfd[1] != STDERR_FILENO && 296 pfd[1] != STDOUT_FILENO) 297 close(pfd[1]); 298 } 299 execvp(argv[0], argv); 300 /* 301 * execvp() failed -- report the error. The child is 302 * now running, so the exit status doesn't matter. 303 */ 304 err(1, "%s", argv[0]); 305 } 306 setproctitle("%s[%d]", title, (int)pid); 307 /* 308 * As we have closed the write end of pipe for parent process, 309 * we might detect the child's exit by reading EOF. The child 310 * might have closed its stdout and stderr, so we must wait for 311 * the SIGCHLD to ensure that the process is actually gone. 312 */ 313 child_eof = 0; 314 for (;;) { 315 /* 316 * We block SIGCHLD when listening, but SIGTERM we accept 317 * so the read() won't block if we wish to depart. 318 * 319 * Upon receiving SIGTERM, we have several options after 320 * sending the SIGTERM to our child: 321 * - read until EOF 322 * - read until EOF but only for a while 323 * - bail immediately 324 * 325 * We go for the third, as otherwise we have no guarantee 326 * that we won't block indefinitely if the child refuses 327 * to depart. To handle the second option, a different 328 * approach would be needed (procctl()?) 329 */ 330 if (child_gone && child_eof) { 331 break; 332 } else if (terminate) { 333 goto exit; 334 } else if (!child_eof) { 335 if (sigprocmask(SIG_BLOCK, &mask_read, NULL)) { 336 warn("sigprocmask"); 337 goto exit; 338 } 339 child_eof = !listen_child(pfd[0], &logpar); 340 if (sigprocmask(SIG_UNBLOCK, &mask_read, NULL)) { 341 warn("sigprocmask"); 342 goto exit; 343 } 344 } else { 345 if (sigprocmask(SIG_BLOCK, &mask_susp, NULL)) { 346 warn("sigprocmask"); 347 goto exit; 348 } 349 while (!terminate && !child_gone) 350 sigsuspend(&mask_orig); 351 if (sigprocmask(SIG_UNBLOCK, &mask_susp, NULL)) { 352 warn("sigprocmask"); 353 goto exit; 354 } 355 } 356 } 357 if (sigprocmask(SIG_BLOCK, &mask_term, NULL)) { 358 warn("sigprocmask"); 359 goto exit; 360 } 361 if (restart && !terminate) { 362 daemon_sleep(1, 0); 363 close(pfd[0]); 364 pfd[0] = -1; 365 goto restart; 366 } 367 exit: 368 close(outfd); 369 close(pfd[0]); 370 close(pfd[1]); 371 if (dosyslog) 372 closelog(); 373 pidfile_remove(pfh); 374 pidfile_remove(ppfh); 375 exit(1); /* If daemon(3) succeeded exit status does not matter. */ 376 } 377 378 static void 379 daemon_sleep(time_t secs, long nsecs) 380 { 381 struct timespec ts = { secs, nsecs }; 382 while (nanosleep(&ts, &ts) == -1) { 383 if (errno != EINTR) 384 err(1, "nanosleep"); 385 } 386 } 387 388 static void 389 open_pid_files(const char *pidfile, const char *ppidfile, 390 struct pidfh **pfh, struct pidfh **ppfh) 391 { 392 pid_t fpid; 393 int serrno; 394 395 if (pidfile) { 396 *pfh = pidfile_open(pidfile, 0600, &fpid); 397 if (*pfh == NULL) { 398 if (errno == EEXIST) { 399 errx(3, "process already running, pid: %d", 400 fpid); 401 } 402 err(2, "pidfile ``%s''", pidfile); 403 } 404 } 405 /* Do the same for the actual daemon process. */ 406 if (ppidfile) { 407 *ppfh = pidfile_open(ppidfile, 0600, &fpid); 408 if (*ppfh == NULL) { 409 serrno = errno; 410 pidfile_remove(*pfh); 411 errno = serrno; 412 if (errno == EEXIST) { 413 errx(3, "process already running, pid: %d", 414 fpid); 415 } 416 err(2, "ppidfile ``%s''", ppidfile); 417 } 418 } 419 } 420 421 static int 422 get_log_mapping(const char *str, const CODE *c) 423 { 424 const CODE *cp; 425 for (cp = c; cp->c_name; cp++) 426 if (strcmp(cp->c_name, str) == 0) 427 return cp->c_val; 428 return -1; 429 } 430 431 static void 432 restrict_process(const char *user) 433 { 434 struct passwd *pw = NULL; 435 436 pw = getpwnam(user); 437 if (pw == NULL) 438 errx(1, "unknown user: %s", user); 439 440 if (setusercontext(NULL, pw, pw->pw_uid, LOGIN_SETALL) != 0) 441 errx(1, "failed to set user environment"); 442 } 443 444 /* 445 * We try to collect whole lines terminated by '\n'. Otherwise we collect a 446 * full buffer, and then output it. 447 * 448 * Return value of 0 is assumed to mean EOF or error, and 1 indicates to 449 * continue reading. 450 */ 451 static int 452 listen_child(int fd, struct log_params *logpar) 453 { 454 static unsigned char buf[LBUF_SIZE]; 455 static size_t bytes_read = 0; 456 int rv; 457 458 assert(logpar); 459 assert(bytes_read < LBUF_SIZE - 1); 460 461 rv = read(fd, buf + bytes_read, LBUF_SIZE - bytes_read - 1); 462 if (rv > 0) { 463 unsigned char *cp; 464 465 bytes_read += rv; 466 assert(bytes_read <= LBUF_SIZE - 1); 467 /* Always NUL-terminate just in case. */ 468 buf[LBUF_SIZE - 1] = '\0'; 469 /* 470 * Chomp line by line until we run out of buffer. 471 * This does not take NUL characters into account. 472 */ 473 while ((cp = memchr(buf, '\n', bytes_read)) != NULL) { 474 size_t bytes_line = cp - buf + 1; 475 assert(bytes_line <= bytes_read); 476 do_output(buf, bytes_line, logpar); 477 bytes_read -= bytes_line; 478 memmove(buf, cp + 1, bytes_read); 479 } 480 /* Wait until the buffer is full. */ 481 if (bytes_read < LBUF_SIZE - 1) 482 return 1; 483 do_output(buf, bytes_read, logpar); 484 bytes_read = 0; 485 return 1; 486 } else if (rv == -1) { 487 /* EINTR should trigger another read. */ 488 if (errno == EINTR) { 489 return 1; 490 } else { 491 warn("read"); 492 return 0; 493 } 494 } 495 /* Upon EOF, we have to flush what's left of the buffer. */ 496 if (bytes_read > 0) { 497 do_output(buf, bytes_read, logpar); 498 bytes_read = 0; 499 } 500 return 0; 501 } 502 503 /* 504 * The default behavior is to stay silent if the user wants to redirect 505 * output to a file and/or syslog. If neither are provided, then we bounce 506 * everything back to parent's stdout. 507 */ 508 static void 509 do_output(const unsigned char *buf, size_t len, struct log_params *logpar) 510 { 511 assert(len <= LBUF_SIZE); 512 assert(logpar); 513 514 if (len < 1) 515 return; 516 if (logpar->dosyslog) 517 syslog(logpar->logpri, "%.*s", (int)len, buf); 518 if (logpar->outfd != -1) { 519 if (write(logpar->outfd, buf, len) == -1) 520 warn("write"); 521 } 522 if (logpar->noclose && !logpar->dosyslog && logpar->outfd == -1) 523 printf("%.*s", (int)len, buf); 524 } 525 526 /* 527 * We use the global PID acquired directly from fork. If there is no valid 528 * child pid, the handler should be blocked and/or child_gone == 1. 529 */ 530 static void 531 handle_term(int signo) 532 { 533 if (pid > 0 && !child_gone) 534 kill(pid, signo); 535 terminate = 1; 536 } 537 538 static void 539 handle_chld(int signo) 540 { 541 (void)signo; 542 for (;;) { 543 int rv = waitpid(-1, NULL, WNOHANG); 544 if (pid == rv) { 545 child_gone = 1; 546 break; 547 } else if (rv == -1 && errno != EINTR) { 548 warn("waitpid"); 549 return; 550 } 551 } 552 } 553 554 static void 555 usage(void) 556 { 557 (void)fprintf(stderr, 558 "usage: daemon [-cfrS] [-p child_pidfile] [-P supervisor_pidfile]\n" 559 " [-u user] [-o output_file] [-t title]\n" 560 " [-l syslog_facility] [-s syslog_priority]\n" 561 " [-T syslog_tag] [-m output_mask]\n" 562 "command arguments ...\n"); 563 exit(1); 564 } 565