atrun.c revision 1.4.2.1
1 /* $NetBSD: atrun.c,v 1.4.2.1 1998/10/25 22:55:32 cgd Exp $ */ 2 3 /* 4 * atrun.c - run jobs queued by at; run with root privileges. 5 * Copyright (C) 1993, 1994 Thomas Koenig 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. The name of the author(s) may not be used to endorse or promote 13 * products derived from this software without specific prior written 14 * permission. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR 17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 19 * IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 23 * THEORY OF LIABILITY, WETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26 */ 27 28 /* System Headers */ 29 30 #include <sys/fcntl.h> 31 #include <sys/types.h> 32 #include <sys/stat.h> 33 #include <sys/wait.h> 34 #include <sys/param.h> 35 #include <ctype.h> 36 #include <dirent.h> 37 #include <errno.h> 38 #include <pwd.h> 39 #include <grp.h> 40 #include <signal.h> 41 #include <stddef.h> 42 #include <stdio.h> 43 #include <stdlib.h> 44 #include <string.h> 45 #include <time.h> 46 #include <unistd.h> 47 #include <syslog.h> 48 #include <utmp.h> 49 50 #include <paths.h> 51 52 /* Local headers */ 53 54 #define MAIN 55 #include "privs.h" 56 #include "pathnames.h" 57 #include "atrun.h" 58 59 /* File scope defines */ 60 61 #if (MAXLOGNAME-1) > UT_NAMESIZE 62 #define LOGNAMESIZE UT_NAMESIZE 63 #else 64 #define LOGNAMESIZE (MAXLOGNAME-1) 65 #endif 66 67 /* File scope variables */ 68 69 static char *namep; 70 #if 0 71 static char rcsid[] = "$OpenBSD: atrun.c,v 1.7 1997/09/08 22:12:10 millert Exp $"; 72 #else 73 __RCSID("$NetBSD: atrun.c,v 1.4.2.1 1998/10/25 22:55:32 cgd Exp $"); 74 #endif 75 76 static int debug = 0; 77 78 /* Local functions */ 79 static void perr __P((const char *)); 80 static void perr2 __P((char *, char *)); 81 static int write_string __P((int, const char *)); 82 static void run_file __P((const char *, uid_t, gid_t)); 83 static void become_user __P((struct passwd *, uid_t)); 84 85 int main __P((int, char *[])); 86 87 static void 88 perr(a) 89 const char *a; 90 { 91 if (debug) 92 perror(a); 93 else 94 syslog(LOG_ERR, "%s: %m", a); 95 96 exit(EXIT_FAILURE); 97 } 98 99 static void 100 perr2(a, b) 101 char *a, *b; 102 { 103 if (debug) { 104 (void)fputs(a, stderr); 105 perror(b); 106 } else 107 syslog(LOG_ERR, "%s%s: %m", a, b); 108 109 exit(EXIT_FAILURE); 110 } 111 112 static int 113 write_string(fd, a) 114 int fd; 115 const char *a; 116 { 117 return(write(fd, a, strlen(a))); 118 } 119 120 static void 121 become_user(pentry, uid) 122 struct passwd *pentry; 123 uid_t uid; 124 { 125 if (initgroups(pentry->pw_name, pentry->pw_gid) < 0) 126 perr("Cannot init group list"); 127 128 if (setegid(pentry->pw_gid) < 0 || setgid(pentry->pw_gid) < 0) 129 perr("Cannot change primary group"); 130 131 if (setlogin(pentry->pw_name) < 0) 132 perr("Cannot set login name"); 133 134 if (setuid(uid) < 0 || seteuid(uid) < 0) 135 perr("Cannot set user id"); 136 137 if (chdir(pentry->pw_dir) < 0) 138 chdir("/"); 139 } 140 141 static void 142 run_file(filename, uid, gid) 143 const char *filename; 144 uid_t uid; 145 gid_t gid; 146 { 147 /* 148 * Run a file by by spawning off a process which redirects I/O, 149 * spawns a subshell, then waits for it to complete and spawns another 150 * process to send mail to the user. 151 */ 152 pid_t pid; 153 int fd_out, fd_in; 154 int queue; 155 char mailbuf[LOGNAMESIZE + 1], fmt[49]; 156 char *mailname = NULL; 157 FILE *stream; 158 int send_mail = 0; 159 struct stat buf, lbuf; 160 off_t size; 161 struct passwd *pentry; 162 int fflags; 163 uid_t nuid; 164 gid_t ngid; 165 166 PRIV_START 167 168 if (chmod(filename, S_IRUSR) != 0) 169 perr("Cannot change file permissions"); 170 171 PRIV_END 172 173 pid = fork(); 174 if (pid == -1) 175 perr("Cannot fork"); 176 else if (pid != 0) 177 return; 178 179 /* 180 * Let's see who we mail to. Hopefully, we can read it from the 181 * command file; if not, send it to the owner, or, failing that, to 182 * root. 183 */ 184 185 pentry = getpwuid(uid); 186 if (pentry == NULL) { 187 syslog(LOG_ERR,"Userid %u not found - aborting job %s", 188 uid, filename); 189 exit(EXIT_FAILURE); 190 } 191 PRIV_START 192 193 stream = fopen(filename, "r"); 194 195 PRIV_END 196 197 if (pentry->pw_expire && time(NULL) >= pentry->pw_expire) { 198 syslog(LOG_ERR, "Userid %u has expired - aborting job %s", 199 uid, filename); 200 exit(EXIT_FAILURE); 201 } 202 203 if (stream == NULL) 204 perr("Cannot open input file"); 205 206 if ((fd_in = dup(fileno(stream))) < 0) 207 perr("Error duplicating input file descriptor"); 208 209 if (fstat(fd_in, &buf) == -1) 210 perr("Error in fstat of input file descriptor"); 211 212 PRIV_START 213 214 if (lstat(filename, &lbuf) == -1) 215 perr("Error in lstat of input file"); 216 217 PRIV_END 218 219 if (S_ISLNK(lbuf.st_mode)) { 220 syslog(LOG_ERR, "Symbolic link encountered in job %s - aborting", 221 filename); 222 exit(EXIT_FAILURE); 223 } 224 if ((lbuf.st_dev != buf.st_dev) || (lbuf.st_ino != buf.st_ino) || 225 (lbuf.st_uid != buf.st_uid) || (lbuf.st_gid != buf.st_gid) || 226 (lbuf.st_size!=buf.st_size)) { 227 syslog(LOG_ERR, "Somebody changed files from under us for job %s - aborting", filename); 228 exit(EXIT_FAILURE); 229 } 230 if (buf.st_nlink > 1) { 231 syslog(LOG_ERR, "Somebody is trying to run a linked script for job %s", 232 filename); 233 exit(EXIT_FAILURE); 234 } 235 if ((fflags = fcntl(fd_in, F_GETFD)) < 0) 236 perr("Error in fcntl"); 237 238 (void)fcntl(fd_in, F_SETFD, fflags & ~FD_CLOEXEC); 239 240 (void)snprintf(fmt, sizeof(fmt), 241 "#!/bin/sh\n# atrun uid=%%ld gid=%%ld\n# mail %%%ds %%d", 242 LOGNAMESIZE); 243 if (fscanf(stream, fmt, &nuid, &ngid, mailbuf, &send_mail) != 4) { 244 syslog(LOG_ERR, "File %s is in wrong format - aborting", 245 filename); 246 exit(EXIT_FAILURE); 247 } 248 if (mailbuf[0] == '-') { 249 syslog(LOG_ERR, "illegal mail name %s in %s", mailbuf, filename); 250 exit(EXIT_FAILURE); 251 } 252 mailname = mailbuf; 253 if (nuid != uid) { 254 syslog(LOG_ERR, "Job %s - userid %u does not match file uid %u", 255 filename, nuid, uid); 256 exit(EXIT_FAILURE); 257 } 258 if (ngid != gid) { 259 syslog(LOG_ERR, "Job %s - groupid %u does not match file gid %u", 260 filename, ngid, gid); 261 exit(EXIT_FAILURE); 262 } 263 (void)fclose(stream); 264 265 PRIV_START 266 267 if (chdir(_PATH_ATSPOOL) < 0) 268 perr2("Cannot chdir to ", _PATH_ATSPOOL); 269 270 /* 271 * Create a file to hold the output of the job we are about to 272 * run. Write the mail header. 273 */ 274 275 if ((fd_out = open(filename, 276 O_WRONLY | O_CREAT | O_EXCL, S_IWUSR | S_IRUSR)) < 0) 277 perr("Cannot create output file"); 278 279 PRIV_END 280 281 write_string(fd_out, "To: "); 282 write_string(fd_out, mailname); 283 write_string(fd_out, "\nSubject: Output from your job "); 284 write_string(fd_out, filename); 285 write_string(fd_out, "\n\n"); 286 if (fstat(fd_out, &buf) == -1) 287 perr("Error in fstat of output file descriptor"); 288 size = buf.st_size; 289 290 (void)close(STDIN_FILENO); 291 (void)close(STDOUT_FILENO); 292 (void)close(STDERR_FILENO); 293 294 pid = fork(); 295 if (pid < 0) 296 perr("Error in fork"); 297 else if (pid == 0) { 298 char *nul = NULL; 299 char **nenvp = &nul; 300 301 /* 302 * Set up things for the child; we want standard input from 303 * the input file, and standard output and error sent to 304 * our output file. 305 */ 306 if (lseek(fd_in, (off_t) 0, SEEK_SET) < 0) 307 perr("Error in lseek"); 308 309 if (dup(fd_in) != STDIN_FILENO) 310 perr("Error in I/O redirection"); 311 312 if (dup(fd_out) != STDOUT_FILENO) 313 perr("Error in I/O redirection"); 314 315 if (dup(fd_out) != STDERR_FILENO) 316 perr("Error in I/O redirection"); 317 318 (void)close(fd_in); 319 (void)close(fd_out); 320 321 PRIV_START 322 323 if (chdir(_PATH_ATJOBS) < 0) 324 perr2("Cannot chdir to ", _PATH_ATJOBS); 325 326 queue = *filename; 327 328 if (queue > 'b') 329 nice(queue - 'b'); 330 331 become_user(pentry, uid); 332 333 if (execle("/bin/sh", "sh", (char *)NULL, nenvp) != 0) 334 perr("Exec failed for /bin/sh"); 335 336 PRIV_END 337 } 338 /* We're the parent. Let's wait. */ 339 (void)close(fd_in); 340 (void)close(fd_out); 341 waitpid(pid, (int *)NULL, 0); 342 343 /* 344 * Send mail. Unlink the output file first, so it is deleted 345 * after the run. 346 */ 347 PRIV_START 348 349 if (stat(filename, &buf) == -1) 350 perr("Error in stat of output file"); 351 if (open(filename, O_RDONLY) != STDIN_FILENO) 352 perr("Open of jobfile failed"); 353 354 (void)unlink(filename); 355 356 PRIV_END 357 358 if ((buf.st_size != size) || send_mail) { 359 /* Fork off a child for sending mail */ 360 361 PRIV_START 362 363 become_user(pentry, uid); 364 365 execl(_PATH_SENDMAIL, "sendmail", "-F", "Atrun Service", 366 "-odi", "-oem", "-t", (char *) NULL); 367 perr("Exec failed for mail command"); 368 369 PRIV_END 370 } 371 exit(EXIT_SUCCESS); 372 } 373 374 /* Global functions */ 375 376 int 377 main(argc, argv) 378 int argc; 379 char *argv[]; 380 { 381 /* 382 * Browse through _PATH_ATJOBS, checking all the jobfiles wether 383 * they should be executed and or deleted. The queue is coded into 384 * the first byte of the job filename, the date (in minutes since 385 * Eon) as a hex number in the following eight bytes, followed by 386 * a dot and a serial number. A file which has not been executed 387 * yet is denoted by its execute - bit set. For those files which 388 * are to be executed, run_file() is called, which forks off a 389 * child which takes care of I/O redirection, forks off another 390 * child for execution and yet another one, optionally, for sending 391 * mail. Files which already have run are removed during the 392 * next invocation. 393 */ 394 DIR *spool; 395 struct dirent *dirent; 396 struct stat buf; 397 unsigned long ctm; 398 int jobno; 399 char queue; 400 time_t now, run_time; 401 char batch_name[] = "Z2345678901234"; 402 uid_t batch_uid; 403 gid_t batch_gid; 404 int c; 405 int run_batch; 406 double la, load_avg = ATRUN_MAXLOAD; 407 408 /* 409 * We don't need root privileges all the time; running under uid 410 * and gid nobody is fine except for priviledged operations. 411 */ 412 RELINQUISH_PRIVS_ROOT(NOBODY_UID, NOBODY_GID) 413 414 openlog("atrun", LOG_PID, LOG_CRON); 415 416 opterr = 0; 417 errno = 0; 418 while ((c = getopt(argc, argv, "dl:")) != -1) { 419 switch (c) { 420 case 'l': 421 if (sscanf(optarg, "%lf", &load_avg) != 1) 422 perr("garbled option -l"); 423 if (load_avg <= 0.) 424 load_avg = ATRUN_MAXLOAD; 425 break; 426 427 case 'd': 428 debug++; 429 break; 430 431 case '?': 432 perr("unknown option"); 433 break; 434 435 default: 436 perr("idiotic option - aborted"); 437 break; 438 } 439 } 440 441 namep = argv[0]; 442 443 PRIV_START 444 445 if (chdir(_PATH_ATJOBS) != 0) 446 perr2("Cannot change to ", _PATH_ATJOBS); 447 448 449 /* 450 * Main loop. Open spool directory for reading and look over all 451 * the files in there. If the filename indicates that the job 452 * should be run and the x bit is set, fork off a child which sets 453 * its user and group id to that of the files and exec a /bin/sh 454 * which executes the shell script. Unlink older files if they 455 * should no longer be run. For deletion, their r bit has to be 456 * turned on. 457 * 458 * Also, pick the oldest batch job to run, at most one per 459 * invocation of atrun. 460 */ 461 if ((spool = opendir(".")) == NULL) 462 perr2("Cannot read ", _PATH_ATJOBS); 463 464 PRIV_END 465 466 now = time(NULL); 467 run_batch = 0; 468 batch_uid = (uid_t) -1; 469 batch_gid = (gid_t) -1; 470 471 while ((dirent = readdir(spool)) != NULL) { 472 PRIV_START 473 474 if (stat(dirent->d_name, &buf) != 0) 475 perr2("Cannot stat in ", _PATH_ATJOBS); 476 477 PRIV_END 478 479 /* We don't want directories */ 480 if (!S_ISREG(buf.st_mode)) 481 continue; 482 483 if (sscanf(dirent->d_name, "%c%5x%8lx", &queue, &jobno, &ctm) != 3) 484 continue; 485 486 run_time = (time_t) ctm * 60; 487 488 if ((S_IXUSR & buf.st_mode) && (run_time <= now)) { 489 if (isupper(queue) && 490 (strcmp(batch_name, dirent->d_name) > 0)) { 491 run_batch = 1; 492 (void)strncpy(batch_name, dirent->d_name, 493 sizeof(batch_name)); 494 batch_uid = buf.st_uid; 495 batch_gid = buf.st_gid; 496 } 497 498 /* The file is executable and old enough */ 499 if (islower(queue)) 500 run_file(dirent->d_name, buf.st_uid, buf.st_gid); 501 } 502 503 /* Delete older files */ 504 if ((run_time < now) && !(S_IXUSR & buf.st_mode) && 505 (S_IRUSR & buf.st_mode)) { 506 PRIV_START 507 508 (void)unlink(dirent->d_name); 509 510 PRIV_END 511 } 512 } 513 514 /* Run the single batch file, if any */ 515 if (run_batch && ((getloadavg(&la, 1) == 1) && la < load_avg)) 516 run_file(batch_name, batch_uid, batch_gid); 517 518 closelog(); 519 exit(EXIT_SUCCESS); 520 } 521
Indexes created Mon Oct 13 16:09:52 GMT 2025