1 /* 2 * atrun.c - run jobs queued by at; run with root privileges. 3 * Copyright (C) 1993, 1994 Thomas Koenig 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. The name of the author(s) may not be used to endorse or promote 11 * products derived from this software without specific prior written 12 * permission. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR 15 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 16 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 17 * IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT, 18 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 19 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 20 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 21 * THEORY OF LIABILITY, WETHER IN CONTRACT, STRICT LIABILITY, OR TORT 22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 23 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 24 * 25 * $FreeBSD: src/libexec/atrun/atrun.c,v 1.26 2007/06/15 12:02:16 yar Exp $ 26 * $DragonFly: src/libexec/atrun/atrun.c,v 1.5 2004/09/20 19:32:19 joerg Exp $ 27 */ 28 29 /* System Headers */ 30 31 #include <sys/fcntl.h> 32 #include <sys/types.h> 33 #include <sys/stat.h> 34 #include <sys/wait.h> 35 #include <sys/param.h> 36 #include <ctype.h> 37 #include <dirent.h> 38 #include <err.h> 39 #include <grp.h> 40 #include <pwd.h> 41 #include <signal.h> 42 #include <stdarg.h> 43 #include <stddef.h> 44 #include <stdio.h> 45 #include <stdlib.h> 46 #include <string.h> 47 #include <syslog.h> 48 #include <time.h> 49 #include <unistd.h> 50 #include <utmp.h> 51 #include <paths.h> 52 #ifdef LOGIN_CAP 53 #include <login_cap.h> 54 #endif 55 #ifdef PAM 56 #include <security/pam_appl.h> 57 #include <security/openpam.h> 58 #endif 59 60 #if (MAXLOGNAME-1) > UT_NAMESIZE 61 #define LOGNAMESIZE UT_NAMESIZE 62 #else 63 #define LOGNAMESIZE (MAXLOGNAME-1) 64 #endif 65 66 /* Local headers */ 67 68 #include "gloadavg.h" 69 #include "privs.h" 70 71 /* Macros */ 72 73 #ifndef ATJOB_DIR 74 #define ATJOB_DIR "/usr/spool/atjobs/" 75 #endif 76 77 #ifndef ATSPOOL_DIR 78 #define ATSPOOL_DIR "/usr/spool/atspool/" 79 #endif 80 81 #ifndef LOADAVG_MX 82 #define LOADAVG_MX 1.5 83 #endif 84 85 uid_t real_uid, effective_uid; 86 gid_t real_gid, effective_gid; 87 88 /* File scope variables */ 89 90 static const char * const atrun = "atrun"; /* service name for syslog etc. */ 91 static int debug = 0; 92 93 void perr(const char *fmt, ...); 94 void perrx(const char *fmt, ...); 95 static void usage(void); 96 97 /* Local functions */ 98 static int 99 write_string(int fd, const char* a) 100 { 101 return write(fd, a, strlen(a)); 102 } 103 104 #undef DEBUG_FORK 105 #ifdef DEBUG_FORK 106 static pid_t 107 myfork(void) 108 { 109 pid_t res; 110 res = fork(); 111 if (res == 0) 112 kill(getpid(),SIGSTOP); 113 return res; 114 } 115 116 #define fork myfork 117 #endif 118 119 static void 120 run_file(const char *filename, uid_t uid, gid_t gid) 121 { 122 /* Run a file by spawning off a process which redirects I/O, 123 * spawns a subshell, then waits for it to complete and sends 124 * mail to the user. 125 */ 126 pid_t pid; 127 int fd_out, fd_in; 128 int queue; 129 char mailbuf[LOGNAMESIZE + 1], fmt[49]; 130 char *mailname = NULL; 131 FILE *stream; 132 int send_mail = 0; 133 struct stat buf, lbuf; 134 off_t size; 135 struct passwd *pentry; 136 int fflags; 137 uid_t nuid; 138 gid_t ngid; 139 #ifdef PAM 140 pam_handle_t *pamh = NULL; 141 int pam_err; 142 struct pam_conv pamc = { 143 .conv = openpam_nullconv, 144 .appdata_ptr = NULL 145 }; 146 #endif 147 148 PRIV_START 149 150 if (chmod(filename, S_IRUSR) != 0) 151 { 152 perr("cannot change file permissions"); 153 } 154 155 PRIV_END 156 157 pid = fork(); 158 if (pid == -1) 159 perr("cannot fork"); 160 161 else if (pid != 0) 162 return; 163 164 /* Let's see who we mail to. Hopefully, we can read it from 165 * the command file; if not, send it to the owner, or, failing that, 166 * to root. 167 */ 168 169 pentry = getpwuid(uid); 170 if (pentry == NULL) 171 perrx("Userid %lu not found - aborting job %s", 172 (unsigned long) uid, filename); 173 174 #ifdef PAM 175 PRIV_START 176 177 pam_err = pam_start(atrun, pentry->pw_name, &pamc, &pamh); 178 if (pam_err != PAM_SUCCESS) 179 perrx("cannot start PAM: %s", pam_strerror(pamh, pam_err)); 180 181 pam_err = pam_acct_mgmt(pamh, PAM_SILENT); 182 /* Expired password shouldn't prevent the job from running. */ 183 if (pam_err != PAM_SUCCESS && pam_err != PAM_NEW_AUTHTOK_REQD) 184 perrx("Account %s (userid %lu) unavailable for job %s: %s", 185 pentry->pw_name, (unsigned long)uid, 186 filename, pam_strerror(pamh, pam_err)); 187 188 pam_end(pamh, pam_err); 189 190 PRIV_END 191 #endif /* PAM */ 192 193 PRIV_START 194 195 stream=fopen(filename, "r"); 196 197 PRIV_END 198 199 if (stream == NULL) 200 perr("cannot open input file"); 201 202 if ((fd_in = dup(fileno(stream))) <0) 203 perr("error duplicating input file descriptor"); 204 205 if (fstat(fd_in, &buf) == -1) 206 perr("error in fstat of input file descriptor"); 207 208 if (lstat(filename, &lbuf) == -1) 209 perr("error in fstat of input file"); 210 211 if (S_ISLNK(lbuf.st_mode)) 212 perrx("Symbolic link encountered in job %s - aborting", filename); 213 214 if ((lbuf.st_dev != buf.st_dev) || (lbuf.st_ino != buf.st_ino) || 215 (lbuf.st_uid != buf.st_uid) || (lbuf.st_gid != buf.st_gid) || 216 (lbuf.st_size!=buf.st_size)) 217 perrx("Somebody changed files from under us for job %s - aborting", 218 filename); 219 220 if (buf.st_nlink > 1) 221 perrx("Somebody is trying to run a linked script for job %s", filename); 222 223 if ((fflags = fcntl(fd_in, F_GETFD)) <0) 224 perr("error in fcntl"); 225 226 fcntl(fd_in, F_SETFD, fflags & ~FD_CLOEXEC); 227 228 snprintf(fmt, sizeof(fmt), 229 "#!/bin/sh\n# atrun uid=%%ld gid=%%ld\n# mail %%%ds %%d", 230 LOGNAMESIZE); 231 232 if (fscanf(stream, fmt, &nuid, &ngid, mailbuf, &send_mail) != 4) 233 perrx("File %s is in wrong format - aborting", filename); 234 235 if (mailbuf[0] == '-') 236 perrx("Illegal mail name %s in %s", mailbuf, filename); 237 238 mailname = mailbuf; 239 240 if (nuid != uid) 241 perrx("Job %s - userid %ld does not match file uid %lu", 242 filename, nuid, (unsigned long)uid); 243 244 if (ngid != gid) 245 perrx("Job %s - groupid %ld does not match file gid %lu", 246 filename, ngid, (unsigned long)gid); 247 248 fclose(stream); 249 250 if (chdir(ATSPOOL_DIR) < 0) 251 perr("cannot chdir to %s", ATSPOOL_DIR); 252 253 /* Create a file to hold the output of the job we are about to run. 254 * Write the mail header. 255 */ 256 if((fd_out=open(filename, 257 O_WRONLY | O_CREAT | O_EXCL, S_IWUSR | S_IRUSR)) < 0) 258 perr("cannot create output file"); 259 260 write_string(fd_out, "Subject: Output from your job "); 261 write_string(fd_out, filename); 262 write_string(fd_out, "\n\n"); 263 fstat(fd_out, &buf); 264 size = buf.st_size; 265 266 close(STDIN_FILENO); 267 close(STDOUT_FILENO); 268 close(STDERR_FILENO); 269 270 pid = fork(); 271 if (pid < 0) 272 perr("error in fork"); 273 274 else if (pid == 0) 275 { 276 char *nul = NULL; 277 char **nenvp = &nul; 278 279 /* Set up things for the child; we want standard input from the input file, 280 * and standard output and error sent to our output file. 281 */ 282 283 if (lseek(fd_in, (off_t) 0, SEEK_SET) < 0) 284 perr("error in lseek"); 285 286 if (dup(fd_in) != STDIN_FILENO) 287 perr("error in I/O redirection"); 288 289 if (dup(fd_out) != STDOUT_FILENO) 290 perr("error in I/O redirection"); 291 292 if (dup(fd_out) != STDERR_FILENO) 293 perr("error in I/O redirection"); 294 295 close(fd_in); 296 close(fd_out); 297 if (chdir(ATJOB_DIR) < 0) 298 perr("cannot chdir to %s", ATJOB_DIR); 299 300 queue = *filename; 301 302 PRIV_START 303 304 nice(tolower(queue) - 'a'); 305 306 #ifdef LOGIN_CAP 307 /* 308 * For simplicity and safety, set all aspects of the user context 309 * except for a selected subset: Don't set priority, which was 310 * set based on the queue file name according to the tradition. 311 * Don't bother to set environment, including path vars, either 312 * because it will be discarded anyway. Although the job file 313 * should set umask, preset it here just in case. 314 */ 315 if (setusercontext(NULL, pentry, uid, LOGIN_SETALL & 316 ~(LOGIN_SETPRIORITY | LOGIN_SETPATH | LOGIN_SETENV)) != 0) 317 exit(EXIT_FAILURE); /* setusercontext() logged the error */ 318 #else /* LOGIN_CAP */ 319 if (initgroups(pentry->pw_name,pentry->pw_gid)) 320 perr("cannot init group access list"); 321 322 if (setgid(gid) < 0 || setegid(pentry->pw_gid) < 0) 323 perr("cannot change group"); 324 325 if (setlogin(pentry->pw_name)) 326 perr("cannot set login name"); 327 328 if (setuid(uid) < 0 || seteuid(uid) < 0) 329 perr("cannot set user id"); 330 #endif /* LOGIN_CAP */ 331 332 if (chdir(pentry->pw_dir)) 333 chdir("/"); 334 335 if(execle("/bin/sh","sh",NULL, nenvp) != 0) 336 perr("exec failed for /bin/sh"); 337 338 PRIV_END 339 } 340 /* We're the parent. Let's wait. 341 */ 342 close(fd_in); 343 close(fd_out); 344 waitpid(pid, NULL, 0); 345 346 /* Send mail. Unlink the output file first, so it is deleted after 347 * the run. 348 */ 349 stat(filename, &buf); 350 if (open(filename, O_RDONLY) != STDIN_FILENO) 351 perr("open of jobfile failed"); 352 353 unlink(filename); 354 if ((buf.st_size != size) || send_mail) 355 { 356 PRIV_START 357 358 #ifdef LOGIN_CAP 359 /* 360 * This time set full context to run the mailer. 361 */ 362 if (setusercontext(NULL, pentry, uid, LOGIN_SETALL) != 0) 363 exit(EXIT_FAILURE); /* setusercontext() logged the error */ 364 #else /* LOGIN_CAP */ 365 if (initgroups(pentry->pw_name,pentry->pw_gid)) 366 perr("cannot init group access list"); 367 368 if (setgid(gid) < 0 || setegid(pentry->pw_gid) < 0) 369 perr("cannot change group"); 370 371 if (setlogin(pentry->pw_name)) 372 perr("cannot set login name"); 373 374 if (setuid(uid) < 0 || seteuid(uid) < 0) 375 perr("cannot set user id"); 376 #endif /* LOGIN_CAP */ 377 378 if (chdir(pentry->pw_dir)) 379 chdir("/"); 380 381 execl(_PATH_SENDMAIL, "sendmail", "-F", "Atrun Service", 382 "-odi", "-oem", 383 mailname, NULL); 384 perr("exec failed for mail command"); 385 386 PRIV_END 387 } 388 exit(EXIT_SUCCESS); 389 } 390 391 /* Global functions */ 392 393 /* Needed in gloadavg.c */ 394 void 395 perr(const char *fmt, ...) 396 { 397 const char * const fmtadd = ": %m"; 398 char nfmt[strlen(fmt) + strlen(fmtadd) + 1]; 399 va_list ap; 400 401 va_start(ap, fmt); 402 if (debug) 403 { 404 vwarn(fmt, ap); 405 } 406 else 407 { 408 snprintf(nfmt, sizeof(nfmt), "%s%s", fmt, fmtadd); 409 vsyslog(LOG_ERR, nfmt, ap); 410 } 411 va_end(ap); 412 413 exit(EXIT_FAILURE); 414 } 415 416 void 417 perrx(const char *fmt, ...) 418 { 419 va_list ap; 420 421 va_start(ap, fmt); 422 if (debug) 423 vwarnx(fmt, ap); 424 else 425 vsyslog(LOG_ERR, fmt, ap); 426 va_end(ap); 427 428 exit(EXIT_FAILURE); 429 } 430 431 int 432 main(int argc, char *argv[]) 433 { 434 /* Browse through ATJOB_DIR, checking all the jobfiles wether they should 435 * be executed and or deleted. The queue is coded into the first byte of 436 * the job filename, the date (in minutes since Eon) as a hex number in the 437 * following eight bytes, followed by a dot and a serial number. A file 438 * which has not been executed yet is denoted by its execute - bit set. 439 * For those files which are to be executed, run_file() is called, which forks 440 * off a child which takes care of I/O redirection, forks off another child 441 * for execution and yet another one, optionally, for sending mail. 442 * Files which already have run are removed during the next invocation. 443 */ 444 DIR *spool; 445 struct dirent *dirent; 446 struct stat buf; 447 unsigned long ctm; 448 unsigned long jobno; 449 char queue; 450 time_t now, run_time; 451 char batch_name[] = "Z2345678901234"; 452 uid_t batch_uid; 453 gid_t batch_gid; 454 int c; 455 int run_batch; 456 double load_avg = LOADAVG_MX; 457 458 /* We don't need root privileges all the time; running under uid and gid daemon 459 * is fine. 460 */ 461 462 RELINQUISH_PRIVS_ROOT(DAEMON_UID, DAEMON_GID) 463 464 openlog(atrun, LOG_PID, LOG_CRON); 465 466 opterr = 0; 467 while((c=getopt(argc, argv, "dl:"))!= -1) 468 { 469 switch (c) 470 { 471 case 'l': 472 if (sscanf(optarg, "%lf", &load_avg) != 1) 473 perr("garbled option -l"); 474 if (load_avg <= 0.) 475 load_avg = LOADAVG_MX; 476 break; 477 478 case 'd': 479 debug ++; 480 break; 481 482 case '?': 483 default: 484 usage(); 485 } 486 } 487 488 if (chdir(ATJOB_DIR) != 0) 489 perr("cannot change to %s", ATJOB_DIR); 490 491 /* Main loop. Open spool directory for reading and look over all the 492 * files in there. If the filename indicates that the job should be run 493 * and the x bit is set, fork off a child which sets its user and group 494 * id to that of the files and exec a /bin/sh which executes the shell 495 * script. Unlink older files if they should no longer be run. For 496 * deletion, their r bit has to be turned on. 497 * 498 * Also, pick the oldest batch job to run, at most one per invocation of 499 * atrun. 500 */ 501 if ((spool = opendir(".")) == NULL) 502 perr("cannot read %s", ATJOB_DIR); 503 504 now = time(NULL); 505 run_batch = 0; 506 batch_uid = (uid_t) -1; 507 batch_gid = (gid_t) -1; 508 509 while ((dirent = readdir(spool)) != NULL) { 510 if (stat(dirent->d_name,&buf) != 0) 511 perr("cannot stat in %s", ATJOB_DIR); 512 513 /* We don't want directories 514 */ 515 if (!S_ISREG(buf.st_mode)) 516 continue; 517 518 if (sscanf(dirent->d_name,"%c%5lx%8lx",&queue,&jobno,&ctm) != 3) 519 continue; 520 521 run_time = (time_t) ctm*60; 522 523 if ((S_IXUSR & buf.st_mode) && (run_time <=now)) { 524 if (isupper(queue) && (strcmp(batch_name,dirent->d_name) > 0)) { 525 run_batch = 1; 526 strlcpy(batch_name, dirent->d_name, sizeof(batch_name)); 527 batch_uid = buf.st_uid; 528 batch_gid = buf.st_gid; 529 } 530 531 /* The file is executable and old enough 532 */ 533 if (islower(queue)) 534 run_file(dirent->d_name, buf.st_uid, buf.st_gid); 535 } 536 /* Delete older files 537 */ 538 if ((run_time < now) && !(S_IXUSR & buf.st_mode) && (S_IRUSR & buf.st_mode)) 539 unlink(dirent->d_name); 540 } 541 /* run the single batch file, if any 542 */ 543 if (run_batch && (gloadavg() < load_avg)) 544 run_file(batch_name, batch_uid, batch_gid); 545 546 closelog(); 547 exit(EXIT_SUCCESS); 548 } 549 550 static void 551 usage(void) 552 { 553 if (debug) 554 fprintf(stderr, "usage: atrun [-l load_avg] [-d]\n"); 555 else 556 syslog(LOG_ERR, "usage: atrun [-l load_avg] [-d]"); 557 558 exit(EXIT_FAILURE); 559 } 560