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 1.4 2004/02/03 23:24:50 rob 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 #ifdef __DragonFly__ 51 #include <paths.h> 52 #else 53 #include <getopt.h> 54 #endif 55 56 #if (MAXLOGNAME-1) > UT_NAMESIZE 57 #define LOGNAMESIZE UT_NAMESIZE 58 #else 59 #define LOGNAMESIZE (MAXLOGNAME-1) 60 #endif 61 62 /* Local headers */ 63 64 #include "gloadavg.h" 65 #define MAIN 66 #include "privs.h" 67 68 /* Macros */ 69 70 #ifndef ATJOB_DIR 71 #define ATJOB_DIR "/usr/spool/atjobs/" 72 #endif 73 74 #ifndef ATSPOOL_DIR 75 #define ATSPOOL_DIR "/usr/spool/atspool/" 76 #endif 77 78 #ifndef LOADAVG_MX 79 #define LOADAVG_MX 1.5 80 #endif 81 82 /* File scope variables */ 83 84 static debug = 0; 85 86 void perr(const char *a); 87 static void usage (void); 88 89 /* Local functions */ 90 static int 91 write_string(int fd, const char* a) 92 { 93 return write(fd, a, strlen(a)); 94 } 95 96 #undef DEBUG_FORK 97 #ifdef DEBUG_FORK 98 static pid_t 99 myfork() 100 { 101 pid_t res; 102 res = fork(); 103 if (res == 0) 104 kill(getpid(),SIGSTOP); 105 return res; 106 } 107 108 #define fork myfork 109 #endif 110 111 static void 112 run_file(const char *filename, uid_t uid, gid_t gid) 113 { 114 /* Run a file by by spawning off a process which redirects I/O, 115 * spawns a subshell, then waits for it to complete and sends 116 * mail to the user. 117 */ 118 pid_t pid; 119 int fd_out, fd_in; 120 int queue; 121 char mailbuf[LOGNAMESIZE + 1], fmt[49]; 122 char *mailname = NULL; 123 FILE *stream; 124 int send_mail = 0; 125 struct stat buf, lbuf; 126 off_t size; 127 struct passwd *pentry; 128 int fflags; 129 long nuid; 130 long ngid; 131 132 133 PRIV_START 134 135 if (chmod(filename, S_IRUSR) != 0) 136 { 137 perr("cannot change file permissions"); 138 } 139 140 PRIV_END 141 142 pid = fork(); 143 if (pid == -1) 144 perr("cannot fork"); 145 146 else if (pid != 0) 147 return; 148 149 /* Let's see who we mail to. Hopefully, we can read it from 150 * the command file; if not, send it to the owner, or, failing that, 151 * to root. 152 */ 153 154 pentry = getpwuid(uid); 155 if (pentry == NULL) 156 { 157 syslog(LOG_ERR,"Userid %lu not found - aborting job %s", 158 (unsigned long) uid, filename); 159 exit(EXIT_FAILURE); 160 } 161 PRIV_START 162 163 stream=fopen(filename, "r"); 164 165 PRIV_END 166 167 #ifdef __DragonFly__ 168 if (pentry->pw_expire && time(NULL) >= pentry->pw_expire) 169 { 170 syslog(LOG_ERR, "Userid %lu is expired - aborting job %s", 171 (unsigned long) uid, filename); 172 exit(EXIT_FAILURE); 173 } 174 #endif 175 176 if (stream == NULL) 177 perr("cannot open input file"); 178 179 if ((fd_in = dup(fileno(stream))) <0) 180 perr("error duplicating input file descriptor"); 181 182 if (fstat(fd_in, &buf) == -1) 183 perr("error in fstat of input file descriptor"); 184 185 if (lstat(filename, &lbuf) == -1) 186 perr("error in fstat of input file"); 187 188 if (S_ISLNK(lbuf.st_mode)) { 189 syslog(LOG_ERR,"Symbolic link encountered in job %s - aborting", 190 filename); 191 exit(EXIT_FAILURE); 192 } 193 if ((lbuf.st_dev != buf.st_dev) || (lbuf.st_ino != buf.st_ino) || 194 (lbuf.st_uid != buf.st_uid) || (lbuf.st_gid != buf.st_gid) || 195 (lbuf.st_size!=buf.st_size)) { 196 syslog(LOG_ERR,"Somebody changed files from under us for job %s - " 197 "aborting",filename); 198 exit(EXIT_FAILURE); 199 } 200 if (buf.st_nlink > 1) { 201 syslog(LOG_ERR,"Someboy is trying to run a linked script for job %s", 202 filename); 203 exit(EXIT_FAILURE); 204 } 205 if ((fflags = fcntl(fd_in, F_GETFD)) <0) 206 perr("error in fcntl"); 207 208 fcntl(fd_in, F_SETFD, fflags & ~FD_CLOEXEC); 209 210 snprintf(fmt, sizeof(fmt), 211 "#!/bin/sh\n# atrun uid=%%ld gid=%%ld\n# mail %%%ds %%d", 212 LOGNAMESIZE); 213 if (fscanf(stream, fmt, &nuid, &ngid, mailbuf, &send_mail) != 4) { 214 syslog(LOG_ERR,"File %s is in wrong format - aborting", filename); 215 exit(EXIT_FAILURE); 216 } 217 if (mailbuf[0] == '-') { 218 syslog(LOG_ERR,"illegal mail name %s in %s",mailbuf,filename); 219 exit(EXIT_FAILURE); 220 } 221 mailname = mailbuf; 222 if (nuid != uid) { 223 syslog(LOG_ERR,"Job %s - userid %ld does not match file uid %lu", 224 filename, nuid, (unsigned long)uid); 225 exit(EXIT_FAILURE); 226 } 227 if (ngid != gid) { 228 syslog(LOG_ERR,"Job %s - groupid %ld does not match file gid %lu", 229 filename, ngid, (unsigned long)gid); 230 exit(EXIT_FAILURE); 231 } 232 fclose(stream); 233 if (chdir(ATSPOOL_DIR) < 0) 234 perr("cannot chdir to " ATSPOOL_DIR); 235 236 /* Create a file to hold the output of the job we are about to run. 237 * Write the mail header. 238 */ 239 if((fd_out=open(filename, 240 O_WRONLY | O_CREAT | O_EXCL, S_IWUSR | S_IRUSR)) < 0) 241 perr("cannot create output file"); 242 243 write_string(fd_out, "Subject: Output from your job "); 244 write_string(fd_out, filename); 245 write_string(fd_out, "\n\n"); 246 fstat(fd_out, &buf); 247 size = buf.st_size; 248 249 close(STDIN_FILENO); 250 close(STDOUT_FILENO); 251 close(STDERR_FILENO); 252 253 pid = fork(); 254 if (pid < 0) 255 perr("error in fork"); 256 257 else if (pid == 0) 258 { 259 char *nul = NULL; 260 char **nenvp = &nul; 261 262 /* Set up things for the child; we want standard input from the input file, 263 * and standard output and error sent to our output file. 264 */ 265 266 if (lseek(fd_in, (off_t) 0, SEEK_SET) < 0) 267 perr("error in lseek"); 268 269 if (dup(fd_in) != STDIN_FILENO) 270 perr("error in I/O redirection"); 271 272 if (dup(fd_out) != STDOUT_FILENO) 273 perr("error in I/O redirection"); 274 275 if (dup(fd_out) != STDERR_FILENO) 276 perr("error in I/O redirection"); 277 278 close(fd_in); 279 close(fd_out); 280 if (chdir(ATJOB_DIR) < 0) 281 perr("cannot chdir to " ATJOB_DIR); 282 283 queue = *filename; 284 285 PRIV_START 286 287 nice(tolower(queue) - 'a'); 288 289 if (initgroups(pentry->pw_name,pentry->pw_gid)) 290 perr("cannot delete saved userids"); 291 292 if (setgid(gid) < 0 || setegid(pentry->pw_gid) < 0) 293 perr("cannot change group"); 294 295 if (setlogin(pentry->pw_name)) 296 perr("cannot set login name"); 297 298 if (setuid(uid) < 0 || seteuid(uid) < 0) 299 perr("cannot set user id"); 300 301 if (chdir(pentry->pw_dir)) 302 chdir("/"); 303 304 if(execle("/bin/sh","sh",(char *) NULL, nenvp) != 0) 305 perr("exec failed for /bin/sh"); 306 307 PRIV_END 308 } 309 /* We're the parent. Let's wait. 310 */ 311 close(fd_in); 312 close(fd_out); 313 waitpid(pid, (int *) NULL, 0); 314 315 /* Send mail. Unlink the output file first, so it is deleted after 316 * the run. 317 */ 318 stat(filename, &buf); 319 if (open(filename, O_RDONLY) != STDIN_FILENO) 320 perr("open of jobfile failed"); 321 322 unlink(filename); 323 if ((buf.st_size != size) || send_mail) 324 { 325 PRIV_START 326 327 if (initgroups(pentry->pw_name,pentry->pw_gid)) 328 perr("cannot delete saved userids"); 329 330 if (setgid(gid) < 0 || setegid(pentry->pw_gid) < 0) 331 perr("cannot change group"); 332 333 if (setlogin(pentry->pw_name)) 334 perr("cannot set login name"); 335 336 if (setuid(uid) < 0 || seteuid(uid) < 0) 337 perr("cannot set user id"); 338 339 if (chdir(pentry->pw_dir)) 340 chdir("/"); 341 342 #ifdef __DragonFly__ 343 execl(_PATH_SENDMAIL, "sendmail", "-F", "Atrun Service", 344 "-odi", "-oem", 345 mailname, (char *) NULL); 346 #else 347 execl(MAIL_CMD, MAIL_CMD, mailname, (char *) NULL); 348 #endif 349 perr("exec failed for mail command"); 350 351 PRIV_END 352 } 353 exit(EXIT_SUCCESS); 354 } 355 356 /* Global functions */ 357 358 /* Needed in gloadavg.c */ 359 void 360 perr(const char *a) 361 { 362 if (debug) 363 { 364 warn("%s", a); 365 } 366 else 367 syslog(LOG_ERR, "%s: %m", a); 368 369 exit(EXIT_FAILURE); 370 } 371 372 int 373 main(int argc, char *argv[]) 374 { 375 /* Browse through ATJOB_DIR, checking all the jobfiles wether they should 376 * be executed and or deleted. The queue is coded into the first byte of 377 * the job filename, the date (in minutes since Eon) as a hex number in the 378 * following eight bytes, followed by a dot and a serial number. A file 379 * which has not been executed yet is denoted by its execute - bit set. 380 * For those files which are to be executed, run_file() is called, which forks 381 * off a child which takes care of I/O redirection, forks off another child 382 * for execution and yet another one, optionally, for sending mail. 383 * Files which already have run are removed during the next invocation. 384 */ 385 DIR *spool; 386 struct dirent *dirent; 387 struct stat buf; 388 unsigned long ctm; 389 unsigned long jobno; 390 char queue; 391 time_t now, run_time; 392 char batch_name[] = "Z2345678901234"; 393 uid_t batch_uid; 394 gid_t batch_gid; 395 int c; 396 int run_batch; 397 double load_avg = LOADAVG_MX; 398 399 /* We don't need root privileges all the time; running under uid and gid daemon 400 * is fine. 401 */ 402 403 RELINQUISH_PRIVS_ROOT(DAEMON_UID, DAEMON_GID) 404 405 openlog("atrun", LOG_PID, LOG_CRON); 406 407 opterr = 0; 408 while((c=getopt(argc, argv, "dl:"))!= -1) 409 { 410 switch (c) 411 { 412 case 'l': 413 if (sscanf(optarg, "%lf", &load_avg) != 1) 414 perr("garbled option -l"); 415 if (load_avg <= 0.) 416 load_avg = LOADAVG_MX; 417 break; 418 419 case 'd': 420 debug ++; 421 break; 422 423 case '?': 424 default: 425 usage(); 426 } 427 } 428 429 if (chdir(ATJOB_DIR) != 0) 430 perr("cannot change to " ATJOB_DIR); 431 432 /* Main loop. Open spool directory for reading and look over all the 433 * files in there. If the filename indicates that the job should be run 434 * and the x bit is set, fork off a child which sets its user and group 435 * id to that of the files and exec a /bin/sh which executes the shell 436 * script. Unlink older files if they should no longer be run. For 437 * deletion, their r bit has to be turned on. 438 * 439 * Also, pick the oldest batch job to run, at most one per invocation of 440 * atrun. 441 */ 442 if ((spool = opendir(".")) == NULL) 443 perr("cannot read " ATJOB_DIR); 444 445 now = time(NULL); 446 run_batch = 0; 447 batch_uid = (uid_t) -1; 448 batch_gid = (gid_t) -1; 449 450 while ((dirent = readdir(spool)) != NULL) { 451 if (stat(dirent->d_name,&buf) != 0) 452 perr("cannot stat in " ATJOB_DIR); 453 454 /* We don't want directories 455 */ 456 if (!S_ISREG(buf.st_mode)) 457 continue; 458 459 if (sscanf(dirent->d_name,"%c%5lx%8lx",&queue,&jobno,&ctm) != 3) 460 continue; 461 462 run_time = (time_t) ctm*60; 463 464 if ((S_IXUSR & buf.st_mode) && (run_time <=now)) { 465 if (isupper(queue) && (strcmp(batch_name,dirent->d_name) > 0)) { 466 run_batch = 1; 467 strncpy(batch_name, dirent->d_name, sizeof(batch_name)); 468 batch_uid = buf.st_uid; 469 batch_gid = buf.st_gid; 470 } 471 472 /* The file is executable and old enough 473 */ 474 if (islower(queue)) 475 run_file(dirent->d_name, buf.st_uid, buf.st_gid); 476 } 477 /* Delete older files 478 */ 479 if ((run_time < now) && !(S_IXUSR & buf.st_mode) && (S_IRUSR & buf.st_mode)) 480 unlink(dirent->d_name); 481 } 482 /* run the single batch file, if any 483 */ 484 if (run_batch && (gloadavg() < load_avg)) 485 run_file(batch_name, batch_uid, batch_gid); 486 487 closelog(); 488 exit(EXIT_SUCCESS); 489 } 490 491 static void 492 usage() 493 { 494 if (debug) 495 fprintf(stderr, "usage: atrun [-l load_avg] [-d]\n"); 496 else 497 syslog(LOG_ERR, "usage: atrun [-l load_avg] [-d]"); 498 499 exit(EXIT_FAILURE); 500 } 501