1 /* Copyright 1988,1990,1993,1994 by Paul Vixie 2 * All rights reserved 3 * 4 * Distribute freely, except: don't remove my name from the source or 5 * documentation (don't take credit for my work), mark your changes (don't 6 * get me blamed for your possible bugs), don't alter or remove this 7 * notice. May be sold if buildable source is provided to buyer. No 8 * warrantee of any kind, express or implied, is included with this 9 * software; use at your own risk, responsibility for damages (if any) to 10 * anyone resulting from the use of this software rests entirely with the 11 * user. 12 * 13 * Send bug reports, bug fixes, enhancements, requests, flames, etc., and 14 * I'll try to keep a version up to date. I can be reached as follows: 15 * Paul Vixie <paul@vix.com> uunet!decwrl!vixie!paul 16 */ 17 18 #if !defined(lint) && !defined(LINT) 19 static const char rcsid[] = 20 "$FreeBSD$"; 21 #endif 22 23 24 #include "cron.h" 25 #include <sys/signal.h> 26 #if defined(sequent) 27 # include <sys/universe.h> 28 #endif 29 #if defined(SYSLOG) 30 # include <syslog.h> 31 #endif 32 #if defined(LOGIN_CAP) 33 # include <login_cap.h> 34 #endif 35 #ifdef PAM 36 # include <security/pam_appl.h> 37 # include <security/openpam.h> 38 #endif 39 40 41 static void child_process(entry *, user *), 42 do_univ(user *); 43 44 45 void 46 do_command(e, u) 47 entry *e; 48 user *u; 49 { 50 Debug(DPROC, ("[%d] do_command(%s, (%s,%d,%d))\n", 51 getpid(), e->cmd, u->name, e->uid, e->gid)) 52 53 /* fork to become asynchronous -- parent process is done immediately, 54 * and continues to run the normal cron code, which means return to 55 * tick(). the child and grandchild don't leave this function, alive. 56 * 57 * vfork() is unsuitable, since we have much to do, and the parent 58 * needs to be able to run off and fork other processes. 59 */ 60 switch (fork()) { 61 case -1: 62 log_it("CRON",getpid(),"error","can't fork"); 63 break; 64 case 0: 65 /* child process */ 66 pidfile_close(pfh); 67 child_process(e, u); 68 Debug(DPROC, ("[%d] child process done, exiting\n", getpid())) 69 _exit(OK_EXIT); 70 break; 71 default: 72 /* parent process */ 73 break; 74 } 75 Debug(DPROC, ("[%d] main process returning to work\n", getpid())) 76 } 77 78 79 static void 80 child_process(e, u) 81 entry *e; 82 user *u; 83 { 84 int stdin_pipe[2], stdout_pipe[2]; 85 register char *input_data; 86 char *usernm, *mailto; 87 int children = 0; 88 # if defined(LOGIN_CAP) 89 struct passwd *pwd; 90 login_cap_t *lc; 91 # endif 92 93 Debug(DPROC, ("[%d] child_process('%s')\n", getpid(), e->cmd)) 94 95 /* mark ourselves as different to PS command watchers by upshifting 96 * our program name. This has no effect on some kernels. 97 */ 98 setproctitle("running job"); 99 100 /* discover some useful and important environment settings 101 */ 102 usernm = env_get("LOGNAME", e->envp); 103 mailto = env_get("MAILTO", e->envp); 104 105 #ifdef PAM 106 /* use PAM to see if the user's account is available, 107 * i.e., not locked or expired or whatever. skip this 108 * for system tasks from /etc/crontab -- they can run 109 * as any user. 110 */ 111 if (strcmp(u->name, SYS_NAME)) { /* not equal */ 112 pam_handle_t *pamh = NULL; 113 int pam_err; 114 struct pam_conv pamc = { 115 .conv = openpam_nullconv, 116 .appdata_ptr = NULL 117 }; 118 119 Debug(DPROC, ("[%d] checking account with PAM\n", getpid())) 120 121 /* u->name keeps crontab owner name while LOGNAME is the name 122 * of user to run command on behalf of. they should be the 123 * same for a task from a per-user crontab. 124 */ 125 if (strcmp(u->name, usernm)) { 126 log_it(usernm, getpid(), "username ambiguity", u->name); 127 exit(ERROR_EXIT); 128 } 129 130 pam_err = pam_start("cron", usernm, &pamc, &pamh); 131 if (pam_err != PAM_SUCCESS) { 132 log_it("CRON", getpid(), "error", "can't start PAM"); 133 exit(ERROR_EXIT); 134 } 135 136 pam_err = pam_acct_mgmt(pamh, PAM_SILENT); 137 /* Expired password shouldn't prevent the job from running. */ 138 if (pam_err != PAM_SUCCESS && pam_err != PAM_NEW_AUTHTOK_REQD) { 139 log_it(usernm, getpid(), "USER", "account unavailable"); 140 exit(ERROR_EXIT); 141 } 142 143 pam_end(pamh, pam_err); 144 } 145 #endif 146 147 #ifdef USE_SIGCHLD 148 /* our parent is watching for our death by catching SIGCHLD. we 149 * do not care to watch for our children's deaths this way -- we 150 * use wait() explicitly. so we have to disable the signal (which 151 * was inherited from the parent). 152 */ 153 (void) signal(SIGCHLD, SIG_DFL); 154 #else 155 /* on system-V systems, we are ignoring SIGCLD. we have to stop 156 * ignoring it now or the wait() in cron_pclose() won't work. 157 * because of this, we have to wait() for our children here, as well. 158 */ 159 (void) signal(SIGCLD, SIG_DFL); 160 #endif /*BSD*/ 161 162 /* create some pipes to talk to our future child 163 */ 164 if (pipe(stdin_pipe) != 0 || pipe(stdout_pipe) != 0) { 165 log_it("CRON", getpid(), "error", "can't pipe"); 166 exit(ERROR_EXIT); 167 } 168 169 /* since we are a forked process, we can diddle the command string 170 * we were passed -- nobody else is going to use it again, right? 171 * 172 * if a % is present in the command, previous characters are the 173 * command, and subsequent characters are the additional input to 174 * the command. Subsequent %'s will be transformed into newlines, 175 * but that happens later. 176 * 177 * If there are escaped %'s, remove the escape character. 178 */ 179 /*local*/{ 180 register int escaped = FALSE; 181 register int ch; 182 register char *p; 183 184 for (input_data = p = e->cmd; (ch = *input_data); 185 input_data++, p++) { 186 if (p != input_data) 187 *p = ch; 188 if (escaped) { 189 if (ch == '%' || ch == '\\') 190 *--p = ch; 191 escaped = FALSE; 192 continue; 193 } 194 if (ch == '\\') { 195 escaped = TRUE; 196 continue; 197 } 198 if (ch == '%') { 199 *input_data++ = '\0'; 200 break; 201 } 202 } 203 *p = '\0'; 204 } 205 206 /* fork again, this time so we can exec the user's command. 207 */ 208 switch (vfork()) { 209 case -1: 210 log_it("CRON",getpid(),"error","can't vfork"); 211 exit(ERROR_EXIT); 212 /*NOTREACHED*/ 213 case 0: 214 Debug(DPROC, ("[%d] grandchild process Vfork()'ed\n", 215 getpid())) 216 217 if (e->uid == ROOT_UID) 218 Jitter = RootJitter; 219 if (Jitter != 0) { 220 srandom(getpid()); 221 sleep(random() % Jitter); 222 } 223 224 /* write a log message. we've waited this long to do it 225 * because it was not until now that we knew the PID that 226 * the actual user command shell was going to get and the 227 * PID is part of the log message. 228 */ 229 /*local*/{ 230 char *x = mkprints((u_char *)e->cmd, strlen(e->cmd)); 231 232 log_it(usernm, getpid(), "CMD", x); 233 free(x); 234 } 235 236 /* that's the last thing we'll log. close the log files. 237 */ 238 #ifdef SYSLOG 239 closelog(); 240 #endif 241 242 /* get new pgrp, void tty, etc. 243 */ 244 (void) setsid(); 245 246 /* close the pipe ends that we won't use. this doesn't affect 247 * the parent, who has to read and write them; it keeps the 248 * kernel from recording us as a potential client TWICE -- 249 * which would keep it from sending SIGPIPE in otherwise 250 * appropriate circumstances. 251 */ 252 close(stdin_pipe[WRITE_PIPE]); 253 close(stdout_pipe[READ_PIPE]); 254 255 /* grandchild process. make std{in,out} be the ends of 256 * pipes opened by our daddy; make stderr go to stdout. 257 */ 258 close(STDIN); dup2(stdin_pipe[READ_PIPE], STDIN); 259 close(STDOUT); dup2(stdout_pipe[WRITE_PIPE], STDOUT); 260 close(STDERR); dup2(STDOUT, STDERR); 261 262 /* close the pipes we just dup'ed. The resources will remain. 263 */ 264 close(stdin_pipe[READ_PIPE]); 265 close(stdout_pipe[WRITE_PIPE]); 266 267 /* set our login universe. Do this in the grandchild 268 * so that the child can invoke /usr/lib/sendmail 269 * without surprises. 270 */ 271 do_univ(u); 272 273 # if defined(LOGIN_CAP) 274 /* Set user's entire context, but skip the environment 275 * as cron provides a separate interface for this 276 */ 277 if ((pwd = getpwnam(usernm)) == NULL) 278 pwd = getpwuid(e->uid); 279 lc = NULL; 280 if (pwd != NULL) { 281 pwd->pw_gid = e->gid; 282 if (e->class != NULL) 283 lc = login_getclass(e->class); 284 } 285 if (pwd && 286 setusercontext(lc, pwd, e->uid, 287 LOGIN_SETALL & ~(LOGIN_SETPATH|LOGIN_SETENV)) == 0) 288 (void) endpwent(); 289 else { 290 /* fall back to the old method */ 291 (void) endpwent(); 292 # endif 293 /* set our directory, uid and gid. Set gid first, 294 * since once we set uid, we've lost root privileges. 295 */ 296 if (setgid(e->gid) != 0) { 297 log_it(usernm, getpid(), 298 "error", "setgid failed"); 299 exit(ERROR_EXIT); 300 } 301 # if defined(BSD) 302 if (initgroups(usernm, e->gid) != 0) { 303 log_it(usernm, getpid(), 304 "error", "initgroups failed"); 305 exit(ERROR_EXIT); 306 } 307 # endif 308 if (setlogin(usernm) != 0) { 309 log_it(usernm, getpid(), 310 "error", "setlogin failed"); 311 exit(ERROR_EXIT); 312 } 313 if (setuid(e->uid) != 0) { 314 log_it(usernm, getpid(), 315 "error", "setuid failed"); 316 exit(ERROR_EXIT); 317 } 318 /* we aren't root after this..*/ 319 #if defined(LOGIN_CAP) 320 } 321 if (lc != NULL) 322 login_close(lc); 323 #endif 324 chdir(env_get("HOME", e->envp)); 325 326 /* exec the command. 327 */ 328 { 329 char *shell = env_get("SHELL", e->envp); 330 331 # if DEBUGGING 332 if (DebugFlags & DTEST) { 333 fprintf(stderr, 334 "debug DTEST is on, not exec'ing command.\n"); 335 fprintf(stderr, 336 "\tcmd='%s' shell='%s'\n", e->cmd, shell); 337 _exit(OK_EXIT); 338 } 339 # endif /*DEBUGGING*/ 340 execle(shell, shell, "-c", e->cmd, (char *)0, e->envp); 341 warn("execl: couldn't exec `%s'", shell); 342 _exit(ERROR_EXIT); 343 } 344 break; 345 default: 346 /* parent process */ 347 break; 348 } 349 350 children++; 351 352 /* middle process, child of original cron, parent of process running 353 * the user's command. 354 */ 355 356 Debug(DPROC, ("[%d] child continues, closing pipes\n", getpid())) 357 358 /* close the ends of the pipe that will only be referenced in the 359 * grandchild process... 360 */ 361 close(stdin_pipe[READ_PIPE]); 362 close(stdout_pipe[WRITE_PIPE]); 363 364 /* 365 * write, to the pipe connected to child's stdin, any input specified 366 * after a % in the crontab entry. while we copy, convert any 367 * additional %'s to newlines. when done, if some characters were 368 * written and the last one wasn't a newline, write a newline. 369 * 370 * Note that if the input data won't fit into one pipe buffer (2K 371 * or 4K on most BSD systems), and the child doesn't read its stdin, 372 * we would block here. thus we must fork again. 373 */ 374 375 if (*input_data && fork() == 0) { 376 register FILE *out = fdopen(stdin_pipe[WRITE_PIPE], "w"); 377 register int need_newline = FALSE; 378 register int escaped = FALSE; 379 register int ch; 380 381 if (out == NULL) { 382 warn("fdopen failed in child2"); 383 _exit(ERROR_EXIT); 384 } 385 386 Debug(DPROC, ("[%d] child2 sending data to grandchild\n", getpid())) 387 388 /* close the pipe we don't use, since we inherited it and 389 * are part of its reference count now. 390 */ 391 close(stdout_pipe[READ_PIPE]); 392 393 /* translation: 394 * \% -> % 395 * % -> \n 396 * \x -> \x for all x != % 397 */ 398 while ((ch = *input_data++)) { 399 if (escaped) { 400 if (ch != '%') 401 putc('\\', out); 402 } else { 403 if (ch == '%') 404 ch = '\n'; 405 } 406 407 if (!(escaped = (ch == '\\'))) { 408 putc(ch, out); 409 need_newline = (ch != '\n'); 410 } 411 } 412 if (escaped) 413 putc('\\', out); 414 if (need_newline) 415 putc('\n', out); 416 417 /* close the pipe, causing an EOF condition. fclose causes 418 * stdin_pipe[WRITE_PIPE] to be closed, too. 419 */ 420 fclose(out); 421 422 Debug(DPROC, ("[%d] child2 done sending to grandchild\n", getpid())) 423 exit(0); 424 } 425 426 /* close the pipe to the grandkiddie's stdin, since its wicked uncle 427 * ernie back there has it open and will close it when he's done. 428 */ 429 close(stdin_pipe[WRITE_PIPE]); 430 431 children++; 432 433 /* 434 * read output from the grandchild. it's stderr has been redirected to 435 * it's stdout, which has been redirected to our pipe. if there is any 436 * output, we'll be mailing it to the user whose crontab this is... 437 * when the grandchild exits, we'll get EOF. 438 */ 439 440 Debug(DPROC, ("[%d] child reading output from grandchild\n", getpid())) 441 442 /*local*/{ 443 register FILE *in = fdopen(stdout_pipe[READ_PIPE], "r"); 444 register int ch; 445 446 if (in == NULL) { 447 warn("fdopen failed in child"); 448 _exit(ERROR_EXIT); 449 } 450 451 ch = getc(in); 452 if (ch != EOF) { 453 register FILE *mail; 454 register int bytes = 1; 455 int status = 0; 456 457 Debug(DPROC|DEXT, 458 ("[%d] got data (%x:%c) from grandchild\n", 459 getpid(), ch, ch)) 460 461 /* get name of recipient. this is MAILTO if set to a 462 * valid local username; USER otherwise. 463 */ 464 if (mailto == NULL) { 465 /* MAILTO not present, set to USER, 466 * unless globally overriden. 467 */ 468 if (defmailto) 469 mailto = defmailto; 470 else 471 mailto = usernm; 472 } 473 if (mailto && *mailto == '\0') 474 mailto = NULL; 475 476 /* if we are supposed to be mailing, MAILTO will 477 * be non-NULL. only in this case should we set 478 * up the mail command and subjects and stuff... 479 */ 480 481 if (mailto) { 482 register char **env; 483 auto char mailcmd[MAX_COMMAND]; 484 auto char hostname[MAXHOSTNAMELEN]; 485 486 if (gethostname(hostname, MAXHOSTNAMELEN) == -1) 487 hostname[0] = '\0'; 488 hostname[sizeof(hostname) - 1] = '\0'; 489 (void) snprintf(mailcmd, sizeof(mailcmd), 490 MAILARGS, MAILCMD); 491 if (!(mail = cron_popen(mailcmd, "w", e))) { 492 warn("%s", MAILCMD); 493 (void) _exit(ERROR_EXIT); 494 } 495 fprintf(mail, "From: Cron Daemon <%s@%s>\n", 496 usernm, hostname); 497 fprintf(mail, "To: %s\n", mailto); 498 fprintf(mail, "Subject: Cron <%s@%s> %s\n", 499 usernm, first_word(hostname, "."), 500 e->cmd); 501 # if defined(MAIL_DATE) 502 fprintf(mail, "Date: %s\n", 503 arpadate(&TargetTime)); 504 # endif /* MAIL_DATE */ 505 for (env = e->envp; *env; env++) 506 fprintf(mail, "X-Cron-Env: <%s>\n", 507 *env); 508 fprintf(mail, "\n"); 509 510 /* this was the first char from the pipe 511 */ 512 putc(ch, mail); 513 } 514 515 /* we have to read the input pipe no matter whether 516 * we mail or not, but obviously we only write to 517 * mail pipe if we ARE mailing. 518 */ 519 520 while (EOF != (ch = getc(in))) { 521 bytes++; 522 if (mailto) 523 putc(ch, mail); 524 } 525 526 /* only close pipe if we opened it -- i.e., we're 527 * mailing... 528 */ 529 530 if (mailto) { 531 Debug(DPROC, ("[%d] closing pipe to mail\n", 532 getpid())) 533 /* Note: the pclose will probably see 534 * the termination of the grandchild 535 * in addition to the mail process, since 536 * it (the grandchild) is likely to exit 537 * after closing its stdout. 538 */ 539 status = cron_pclose(mail); 540 } 541 542 /* if there was output and we could not mail it, 543 * log the facts so the poor user can figure out 544 * what's going on. 545 */ 546 if (mailto && status) { 547 char buf[MAX_TEMPSTR]; 548 549 snprintf(buf, sizeof(buf), 550 "mailed %d byte%s of output but got status 0x%04x\n", 551 bytes, (bytes==1)?"":"s", 552 status); 553 log_it(usernm, getpid(), "MAIL", buf); 554 } 555 556 } /*if data from grandchild*/ 557 558 Debug(DPROC, ("[%d] got EOF from grandchild\n", getpid())) 559 560 fclose(in); /* also closes stdout_pipe[READ_PIPE] */ 561 } 562 563 /* wait for children to die. 564 */ 565 for (; children > 0; children--) 566 { 567 WAIT_T waiter; 568 PID_T pid; 569 570 Debug(DPROC, ("[%d] waiting for grandchild #%d to finish\n", 571 getpid(), children)) 572 pid = wait(&waiter); 573 if (pid < OK) { 574 Debug(DPROC, ("[%d] no more grandchildren--mail written?\n", 575 getpid())) 576 break; 577 } 578 Debug(DPROC, ("[%d] grandchild #%d finished, status=%04x", 579 getpid(), pid, WEXITSTATUS(waiter))) 580 if (WIFSIGNALED(waiter) && WCOREDUMP(waiter)) 581 Debug(DPROC, (", dumped core")) 582 Debug(DPROC, ("\n")) 583 } 584 } 585 586 587 static void 588 do_univ(u) 589 user *u; 590 { 591 #if defined(sequent) 592 /* Dynix (Sequent) hack to put the user associated with 593 * the passed user structure into the ATT universe if 594 * necessary. We have to dig the gecos info out of 595 * the user's password entry to see if the magic 596 * "universe(att)" string is present. 597 */ 598 599 struct passwd *p; 600 char *s; 601 int i; 602 603 p = getpwuid(u->uid); 604 (void) endpwent(); 605 606 if (p == NULL) 607 return; 608 609 s = p->pw_gecos; 610 611 for (i = 0; i < 4; i++) 612 { 613 if ((s = strchr(s, ',')) == NULL) 614 return; 615 s++; 616 } 617 if (strcmp(s, "universe(att)")) 618 return; 619 620 (void) universe(U_ATT); 621 #endif 622 } 623