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 1.14.2.1 2001/03/05 10:53:23 kris 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 <stddef.h> 43 #include <stdio.h> 44 #include <stdlib.h> 45 #include <string.h> 46 #include <syslog.h> 47 #include <time.h> 48 #include <unistd.h> 49 #include <utmp.h> 50 #include <paths.h> 51 52 #if (MAXLOGNAME-1) > UT_NAMESIZE 53 #define LOGNAMESIZE UT_NAMESIZE 54 #else 55 #define LOGNAMESIZE (MAXLOGNAME-1) 56 #endif 57 58 /* Local headers */ 59 60 #include "gloadavg.h" 61 #include "privs.h" 62 63 /* Macros */ 64 65 #ifndef ATJOB_DIR 66 #define ATJOB_DIR "/usr/spool/atjobs/" 67 #endif 68 69 #ifndef ATSPOOL_DIR 70 #define ATSPOOL_DIR "/usr/spool/atspool/" 71 #endif 72 73 #ifndef LOADAVG_MX 74 #define LOADAVG_MX 1.5 75 #endif 76 77 uid_t real_uid, effective_uid; 78 gid_t real_gid, effective_gid; 79 80 /* File scope variables */ 81 82 static int debug = 0; 83 84 void perr(const char *a); 85 static void usage(void); 86 87 /* Local functions */ 88 static int 89 write_string(int fd, const char* a) 90 { 91 return write(fd, a, strlen(a)); 92 } 93 94 #undef DEBUG_FORK 95 #ifdef DEBUG_FORK 96 static pid_t 97 myfork(void) 98 { 99 pid_t res; 100 res = fork(); 101 if (res == 0) 102 kill(getpid(),SIGSTOP); 103 return res; 104 } 105 106 #define fork myfork 107 #endif 108 109 static void 110 run_file(const char *filename, uid_t uid, gid_t gid) 111 { 112 /* Run a file by by spawning off a process which redirects I/O, 113 * spawns a subshell, then waits for it to complete and sends 114 * mail to the user. 115 */ 116 pid_t pid; 117 int fd_out, fd_in; 118 int queue; 119 char mailbuf[LOGNAMESIZE + 1], fmt[49]; 120 char *mailname = NULL; 121 FILE *stream; 122 int send_mail = 0; 123 struct stat buf, lbuf; 124 off_t size; 125 struct passwd *pentry; 126 int fflags; 127 uid_t nuid; 128 gid_t ngid; 129 130 131 PRIV_START 132 133 if (chmod(filename, S_IRUSR) != 0) 134 { 135 perr("cannot change file permissions"); 136 } 137 138 PRIV_END 139 140 pid = fork(); 141 if (pid == -1) 142 perr("cannot fork"); 143 144 else if (pid != 0) 145 return; 146 147 /* Let's see who we mail to. Hopefully, we can read it from 148 * the command file; if not, send it to the owner, or, failing that, 149 * to root. 150 */ 151 152 pentry = getpwuid(uid); 153 if (pentry == NULL) 154 { 155 syslog(LOG_ERR,"Userid %lu not found - aborting job %s", 156 (unsigned long) uid, filename); 157 exit(EXIT_FAILURE); 158 } 159 PRIV_START 160 161 stream=fopen(filename, "r"); 162 163 PRIV_END 164 165 #ifdef __DragonFly__ 166 if (pentry->pw_expire && time(NULL) >= pentry->pw_expire) 167 { 168 syslog(LOG_ERR, "Userid %lu is expired - aborting job %s", 169 (unsigned long) uid, filename); 170 exit(EXIT_FAILURE); 171 } 172 #endif 173 174 if (stream == NULL) 175 perr("cannot open input file"); 176 177 if ((fd_in = dup(fileno(stream))) <0) 178 perr("error duplicating input file descriptor"); 179 180 if (fstat(fd_in, &buf) == -1) 181 perr("error in fstat of input file descriptor"); 182 183 if (lstat(filename, &lbuf) == -1) 184 perr("error in fstat of input file"); 185 186 if (S_ISLNK(lbuf.st_mode)) { 187 syslog(LOG_ERR,"Symbolic link encountered in job %s - aborting", 188 filename); 189 exit(EXIT_FAILURE); 190 } 191 if ((lbuf.st_dev != buf.st_dev) || (lbuf.st_ino != buf.st_ino) || 192 (lbuf.st_uid != buf.st_uid) || (lbuf.st_gid != buf.st_gid) || 193 (lbuf.st_size!=buf.st_size)) { 194 syslog(LOG_ERR,"Somebody changed files from under us for job %s - " 195 "aborting",filename); 196 exit(EXIT_FAILURE); 197 } 198 if (buf.st_nlink > 1) { 199 syslog(LOG_ERR,"Someboy is trying to run a linked script for job %s", 200 filename); 201 exit(EXIT_FAILURE); 202 } 203 if ((fflags = fcntl(fd_in, F_GETFD)) <0) 204 perr("error in fcntl"); 205 206 fcntl(fd_in, F_SETFD, fflags & ~FD_CLOEXEC); 207 208 snprintf(fmt, sizeof(fmt), 209 "#!/bin/sh\n# atrun uid=%%ld gid=%%ld\n# mail %%%ds %%d", 210 LOGNAMESIZE); 211 if (fscanf(stream, fmt, &nuid, &ngid, mailbuf, &send_mail) != 4) { 212 syslog(LOG_ERR,"File %s is in wrong format - aborting", filename); 213 exit(EXIT_FAILURE); 214 } 215 if (mailbuf[0] == '-') { 216 syslog(LOG_ERR,"illegal mail name %s in %s",mailbuf,filename); 217 exit(EXIT_FAILURE); 218 } 219 mailname = mailbuf; 220 if (nuid != uid) { 221 syslog(LOG_ERR,"Job %s - userid %u does not match file uid %lu", 222 filename, nuid, (unsigned long)uid); 223 exit(EXIT_FAILURE); 224 } 225 if (ngid != gid) { 226 syslog(LOG_ERR,"Job %s - groupid %u does not match file gid %lu", 227 filename, ngid, (unsigned long)gid); 228 exit(EXIT_FAILURE); 229 } 230 fclose(stream); 231 if (chdir(ATSPOOL_DIR) < 0) 232 perr("cannot chdir to " ATSPOOL_DIR); 233 234 /* Create a file to hold the output of the job we are about to run. 235 * Write the mail header. 236 */ 237 if((fd_out=open(filename, 238 O_WRONLY | O_CREAT | O_EXCL, S_IWUSR | S_IRUSR)) < 0) 239 perr("cannot create output file"); 240 241 write_string(fd_out, "Subject: Output from your job "); 242 write_string(fd_out, filename); 243 write_string(fd_out, "\n\n"); 244 fstat(fd_out, &buf); 245 size = buf.st_size; 246 247 close(STDIN_FILENO); 248 close(STDOUT_FILENO); 249 close(STDERR_FILENO); 250 251 pid = fork(); 252 if (pid < 0) 253 perr("error in fork"); 254 255 else if (pid == 0) 256 { 257 char *nul = NULL; 258 char **nenvp = &nul; 259 260 /* Set up things for the child; we want standard input from the input file, 261 * and standard output and error sent to our output file. 262 */ 263 264 if (lseek(fd_in, (off_t) 0, SEEK_SET) < 0) 265 perr("error in lseek"); 266 267 if (dup(fd_in) != STDIN_FILENO) 268 perr("error in I/O redirection"); 269 270 if (dup(fd_out) != STDOUT_FILENO) 271 perr("error in I/O redirection"); 272 273 if (dup(fd_out) != STDERR_FILENO) 274 perr("error in I/O redirection"); 275 276 close(fd_in); 277 close(fd_out); 278 if (chdir(ATJOB_DIR) < 0) 279 perr("cannot chdir to " ATJOB_DIR); 280 281 queue = *filename; 282 283 PRIV_START 284 285 nice(tolower(queue) - 'a'); 286 287 if (initgroups(pentry->pw_name,pentry->pw_gid)) 288 perr("cannot delete saved userids"); 289 290 if (setgid(gid) < 0 || setegid(pentry->pw_gid) < 0) 291 perr("cannot change group"); 292 293 if (setlogin(pentry->pw_name)) 294 perr("cannot set login name"); 295 296 if (setuid(uid) < 0 || seteuid(uid) < 0) 297 perr("cannot set user id"); 298 299 if (chdir(pentry->pw_dir)) 300 chdir("/"); 301 302 if(execle("/bin/sh","sh",(char *) NULL, nenvp) != 0) 303 perr("exec failed for /bin/sh"); 304 305 PRIV_END 306 } 307 /* We're the parent. Let's wait. 308 */ 309 close(fd_in); 310 close(fd_out); 311 waitpid(pid, (int *) NULL, 0); 312 313 /* Send mail. Unlink the output file first, so it is deleted after 314 * the run. 315 */ 316 stat(filename, &buf); 317 if (open(filename, O_RDONLY) != STDIN_FILENO) 318 perr("open of jobfile failed"); 319 320 unlink(filename); 321 if ((buf.st_size != size) || send_mail) 322 { 323 PRIV_START 324 325 if (initgroups(pentry->pw_name,pentry->pw_gid)) 326 perr("cannot delete saved userids"); 327 328 if (setgid(gid) < 0 || setegid(pentry->pw_gid) < 0) 329 perr("cannot change group"); 330 331 if (setlogin(pentry->pw_name)) 332 perr("cannot set login name"); 333 334 if (setuid(uid) < 0 || seteuid(uid) < 0) 335 perr("cannot set user id"); 336 337 if (chdir(pentry->pw_dir)) 338 chdir("/"); 339 340 execl(_PATH_SENDMAIL, "sendmail", "-F", "Atrun Service", 341 "-odi", "-oem", 342 mailname, (char *) NULL); 343 perr("exec failed for mail command"); 344 345 PRIV_END 346 } 347 exit(EXIT_SUCCESS); 348 } 349 350 /* Global functions */ 351 352 /* Needed in gloadavg.c */ 353 void 354 perr(const char *a) 355 { 356 if (debug) 357 { 358 warn("%s", a); 359 } 360 else 361 syslog(LOG_ERR, "%s: %m", a); 362 363 exit(EXIT_FAILURE); 364 } 365 366 int 367 main(int argc, char *argv[]) 368 { 369 /* Browse through ATJOB_DIR, checking all the jobfiles wether they should 370 * be executed and or deleted. The queue is coded into the first byte of 371 * the job filename, the date (in minutes since Eon) as a hex number in the 372 * following eight bytes, followed by a dot and a serial number. A file 373 * which has not been executed yet is denoted by its execute - bit set. 374 * For those files which are to be executed, run_file() is called, which forks 375 * off a child which takes care of I/O redirection, forks off another child 376 * for execution and yet another one, optionally, for sending mail. 377 * Files which already have run are removed during the next invocation. 378 */ 379 DIR *spool; 380 struct dirent *dirent; 381 struct stat buf; 382 unsigned long ctm; 383 unsigned long jobno; 384 char queue; 385 time_t now, run_time; 386 char batch_name[] = "Z2345678901234"; 387 uid_t batch_uid; 388 gid_t batch_gid; 389 int c; 390 int run_batch; 391 double load_avg = LOADAVG_MX; 392 393 /* We don't need root privileges all the time; running under uid and gid daemon 394 * is fine. 395 */ 396 397 RELINQUISH_PRIVS_ROOT(DAEMON_UID, DAEMON_GID) 398 399 openlog("atrun", LOG_PID, LOG_CRON); 400 401 opterr = 0; 402 while((c=getopt(argc, argv, "dl:"))!= -1) 403 { 404 switch (c) 405 { 406 case 'l': 407 if (sscanf(optarg, "%lf", &load_avg) != 1) 408 perr("garbled option -l"); 409 if (load_avg <= 0.) 410 load_avg = LOADAVG_MX; 411 break; 412 413 case 'd': 414 debug ++; 415 break; 416 417 case '?': 418 default: 419 usage(); 420 } 421 } 422 423 if (chdir(ATJOB_DIR) != 0) 424 perr("cannot change to " ATJOB_DIR); 425 426 /* Main loop. Open spool directory for reading and look over all the 427 * files in there. If the filename indicates that the job should be run 428 * and the x bit is set, fork off a child which sets its user and group 429 * id to that of the files and exec a /bin/sh which executes the shell 430 * script. Unlink older files if they should no longer be run. For 431 * deletion, their r bit has to be turned on. 432 * 433 * Also, pick the oldest batch job to run, at most one per invocation of 434 * atrun. 435 */ 436 if ((spool = opendir(".")) == NULL) 437 perr("cannot read " ATJOB_DIR); 438 439 now = time(NULL); 440 run_batch = 0; 441 batch_uid = (uid_t) -1; 442 batch_gid = (gid_t) -1; 443 444 while ((dirent = readdir(spool)) != NULL) { 445 if (stat(dirent->d_name,&buf) != 0) 446 perr("cannot stat in " ATJOB_DIR); 447 448 /* We don't want directories 449 */ 450 if (!S_ISREG(buf.st_mode)) 451 continue; 452 453 if (sscanf(dirent->d_name,"%c%5lx%8lx",&queue,&jobno,&ctm) != 3) 454 continue; 455 456 run_time = (time_t) ctm*60; 457 458 if ((S_IXUSR & buf.st_mode) && (run_time <=now)) { 459 if (isupper(queue) && (strcmp(batch_name,dirent->d_name) > 0)) { 460 run_batch = 1; 461 strncpy(batch_name, dirent->d_name, sizeof(batch_name)); 462 batch_uid = buf.st_uid; 463 batch_gid = buf.st_gid; 464 } 465 466 /* The file is executable and old enough 467 */ 468 if (islower(queue)) 469 run_file(dirent->d_name, buf.st_uid, buf.st_gid); 470 } 471 /* Delete older files 472 */ 473 if ((run_time < now) && !(S_IXUSR & buf.st_mode) && (S_IRUSR & buf.st_mode)) 474 unlink(dirent->d_name); 475 } 476 /* run the single batch file, if any 477 */ 478 if (run_batch && (gloadavg() < load_avg)) 479 run_file(batch_name, batch_uid, batch_gid); 480 481 closelog(); 482 exit(EXIT_SUCCESS); 483 } 484 485 static void 486 usage() 487 { 488 if (debug) 489 fprintf(stderr, "usage: atrun [-l load_avg] [-d]\n"); 490 else 491 syslog(LOG_ERR, "usage: atrun [-l load_avg] [-d]"); 492 493 exit(EXIT_FAILURE); 494 } 495