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 * $FreeBSD: src/usr.sbin/cron/cron/do_command.c,v 1.15.2.5 2001/05/04 00:59:40 peter Exp $ 18 * $DragonFly: src/usr.sbin/cron/cron/do_command.c,v 1.4 2003/11/16 11:51:14 eirikn Exp $ 19 */ 20 21 #include "cron.h" 22 #include <sys/signal.h> 23 #if defined(sequent) 24 # include <sys/universe.h> 25 #endif 26 #if defined(SYSLOG) 27 # include <syslog.h> 28 #endif 29 #if defined(LOGIN_CAP) 30 # include <login_cap.h> 31 #endif 32 33 34 static void child_process(entry *, user *), 35 do_univ(user *); 36 37 38 void 39 do_command(entry *e, user *u) 40 { 41 Debug(DPROC, ("[%d] do_command(%s, (%s,%d,%d))\n", 42 getpid(), e->cmd, u->name, e->uid, e->gid)) 43 44 /* fork to become asynchronous -- parent process is done immediately, 45 * and continues to run the normal cron code, which means return to 46 * tick(). the child and grandchild don't leave this function, alive. 47 * 48 * vfork() is unsuitable, since we have much to do, and the parent 49 * needs to be able to run off and fork other processes. 50 */ 51 switch (fork()) { 52 case -1: 53 log_it("CRON",getpid(),"error","can't fork"); 54 break; 55 case 0: 56 /* child process */ 57 acquire_daemonlock(1); 58 child_process(e, u); 59 Debug(DPROC, ("[%d] child process done, exiting\n", getpid())) 60 _exit(OK_EXIT); 61 break; 62 default: 63 /* parent process */ 64 break; 65 } 66 Debug(DPROC, ("[%d] main process returning to work\n", getpid())) 67 } 68 69 70 static void 71 child_process(entry *e, user *u) 72 { 73 int stdin_pipe[2], stdout_pipe[2]; 74 register char *input_data; 75 char *usernm, *mailto; 76 int children = 0; 77 # if defined(LOGIN_CAP) 78 struct passwd *pwd; 79 login_cap_t *lc; 80 # endif 81 82 Debug(DPROC, ("[%d] child_process('%s')\n", getpid(), e->cmd)) 83 84 /* mark ourselves as different to PS command watchers by upshifting 85 * our program name. This has no effect on some kernels. 86 */ 87 setproctitle("running job"); 88 89 /* discover some useful and important environment settings 90 */ 91 usernm = env_get("LOGNAME", e->envp); 92 mailto = env_get("MAILTO", e->envp); 93 94 #ifdef USE_SIGCHLD 95 /* our parent is watching for our death by catching SIGCHLD. we 96 * do not care to watch for our children's deaths this way -- we 97 * use wait() explictly. so we have to disable the signal (which 98 * was inherited from the parent). 99 */ 100 (void) signal(SIGCHLD, SIG_DFL); 101 #else 102 /* on system-V systems, we are ignoring SIGCLD. we have to stop 103 * ignoring it now or the wait() in cron_pclose() won't work. 104 * because of this, we have to wait() for our children here, as well. 105 */ 106 (void) signal(SIGCLD, SIG_DFL); 107 #endif /*BSD*/ 108 109 /* create some pipes to talk to our future child 110 */ 111 pipe(stdin_pipe); /* child's stdin */ 112 pipe(stdout_pipe); /* child's stdout */ 113 114 /* since we are a forked process, we can diddle the command string 115 * we were passed -- nobody else is going to use it again, right? 116 * 117 * if a % is present in the command, previous characters are the 118 * command, and subsequent characters are the additional input to 119 * the command. Subsequent %'s will be transformed into newlines, 120 * but that happens later. 121 * 122 * If there are escaped %'s, remove the escape character. 123 */ 124 /*local*/{ 125 register int escaped = FALSE; 126 register int ch; 127 register char *p; 128 129 for (input_data = p = e->cmd; (ch = *input_data); 130 input_data++, p++) { 131 if (p != input_data) 132 *p = ch; 133 if (escaped) { 134 if (ch == '%' || ch == '\\') 135 *--p = ch; 136 escaped = FALSE; 137 continue; 138 } 139 if (ch == '\\') { 140 escaped = TRUE; 141 continue; 142 } 143 if (ch == '%') { 144 *input_data++ = '\0'; 145 break; 146 } 147 } 148 *p = '\0'; 149 } 150 151 /* fork again, this time so we can exec the user's command. 152 */ 153 switch (vfork()) { 154 case -1: 155 log_it("CRON",getpid(),"error","can't vfork"); 156 exit(ERROR_EXIT); 157 /*NOTREACHED*/ 158 case 0: 159 Debug(DPROC, ("[%d] grandchild process Vfork()'ed\n", 160 getpid())) 161 162 /* write a log message. we've waited this long to do it 163 * because it was not until now that we knew the PID that 164 * the actual user command shell was going to get and the 165 * PID is part of the log message. 166 */ 167 /*local*/{ 168 char *x = mkprints((u_char *)e->cmd, strlen(e->cmd)); 169 170 log_it(usernm, getpid(), "CMD", x); 171 free(x); 172 } 173 174 /* that's the last thing we'll log. close the log files. 175 */ 176 #ifdef SYSLOG 177 closelog(); 178 #endif 179 180 /* get new pgrp, void tty, etc. 181 */ 182 (void) setsid(); 183 184 /* close the pipe ends that we won't use. this doesn't affect 185 * the parent, who has to read and write them; it keeps the 186 * kernel from recording us as a potential client TWICE -- 187 * which would keep it from sending SIGPIPE in otherwise 188 * appropriate circumstances. 189 */ 190 close(stdin_pipe[WRITE_PIPE]); 191 close(stdout_pipe[READ_PIPE]); 192 193 /* grandchild process. make std{in,out} be the ends of 194 * pipes opened by our daddy; make stderr go to stdout. 195 */ 196 close(STDIN); dup2(stdin_pipe[READ_PIPE], STDIN); 197 close(STDOUT); dup2(stdout_pipe[WRITE_PIPE], STDOUT); 198 close(STDERR); dup2(STDOUT, STDERR); 199 200 /* close the pipes we just dup'ed. The resources will remain. 201 */ 202 close(stdin_pipe[READ_PIPE]); 203 close(stdout_pipe[WRITE_PIPE]); 204 205 /* set our login universe. Do this in the grandchild 206 * so that the child can invoke /usr/lib/sendmail 207 * without surprises. 208 */ 209 do_univ(u); 210 211 # if defined(LOGIN_CAP) 212 /* Set user's entire context, but skip the environment 213 * as cron provides a separate interface for this 214 */ 215 if ((pwd = getpwnam(usernm)) == NULL) 216 pwd = getpwuid(e->uid); 217 lc = NULL; 218 if (pwd != NULL) { 219 pwd->pw_gid = e->gid; 220 if (e->class != NULL) 221 lc = login_getclass(e->class); 222 } 223 if (pwd && 224 setusercontext(lc, pwd, e->uid, 225 LOGIN_SETALL & ~(LOGIN_SETPATH|LOGIN_SETENV)) == 0) 226 (void) endpwent(); 227 else { 228 /* fall back to the old method */ 229 (void) endpwent(); 230 # endif 231 /* set our directory, uid and gid. Set gid first, 232 * since once we set uid, we've lost root privledges. 233 */ 234 setgid(e->gid); 235 # if defined(BSD) 236 initgroups(usernm, e->gid); 237 # endif 238 setlogin(usernm); 239 setuid(e->uid); /* we aren't root after this..*/ 240 #if defined(LOGIN_CAP) 241 } 242 if (lc != NULL) 243 login_close(lc); 244 #endif 245 chdir(env_get("HOME", e->envp)); 246 247 /* exec the command. 248 */ 249 { 250 char *shell = env_get("SHELL", e->envp); 251 252 # if DEBUGGING 253 if (DebugFlags & DTEST) { 254 fprintf(stderr, 255 "debug DTEST is on, not exec'ing command.\n"); 256 fprintf(stderr, 257 "\tcmd='%s' shell='%s'\n", e->cmd, shell); 258 _exit(OK_EXIT); 259 } 260 # endif /*DEBUGGING*/ 261 execle(shell, shell, "-c", e->cmd, (char *)0, e->envp); 262 warn("execl: couldn't exec `%s'", shell); 263 _exit(ERROR_EXIT); 264 } 265 break; 266 default: 267 /* parent process */ 268 break; 269 } 270 271 children++; 272 273 /* middle process, child of original cron, parent of process running 274 * the user's command. 275 */ 276 277 Debug(DPROC, ("[%d] child continues, closing pipes\n", getpid())) 278 279 /* close the ends of the pipe that will only be referenced in the 280 * grandchild process... 281 */ 282 close(stdin_pipe[READ_PIPE]); 283 close(stdout_pipe[WRITE_PIPE]); 284 285 /* 286 * write, to the pipe connected to child's stdin, any input specified 287 * after a % in the crontab entry. while we copy, convert any 288 * additional %'s to newlines. when done, if some characters were 289 * written and the last one wasn't a newline, write a newline. 290 * 291 * Note that if the input data won't fit into one pipe buffer (2K 292 * or 4K on most BSD systems), and the child doesn't read its stdin, 293 * we would block here. thus we must fork again. 294 */ 295 296 if (*input_data && fork() == 0) { 297 register FILE *out = fdopen(stdin_pipe[WRITE_PIPE], "w"); 298 register int need_newline = FALSE; 299 register int escaped = FALSE; 300 register int ch; 301 302 if (out == NULL) { 303 warn("fdopen failed in child2"); 304 _exit(ERROR_EXIT); 305 } 306 307 Debug(DPROC, ("[%d] child2 sending data to grandchild\n", getpid())) 308 309 /* close the pipe we don't use, since we inherited it and 310 * are part of its reference count now. 311 */ 312 close(stdout_pipe[READ_PIPE]); 313 314 /* translation: 315 * \% -> % 316 * % -> \n 317 * \x -> \x for all x != % 318 */ 319 while ((ch = *input_data++)) { 320 if (escaped) { 321 if (ch != '%') 322 putc('\\', out); 323 } else { 324 if (ch == '%') 325 ch = '\n'; 326 } 327 328 if (!(escaped = (ch == '\\'))) { 329 putc(ch, out); 330 need_newline = (ch != '\n'); 331 } 332 } 333 if (escaped) 334 putc('\\', out); 335 if (need_newline) 336 putc('\n', out); 337 338 /* close the pipe, causing an EOF condition. fclose causes 339 * stdin_pipe[WRITE_PIPE] to be closed, too. 340 */ 341 fclose(out); 342 343 Debug(DPROC, ("[%d] child2 done sending to grandchild\n", getpid())) 344 exit(0); 345 } 346 347 /* close the pipe to the grandkiddie's stdin, since its wicked uncle 348 * ernie back there has it open and will close it when he's done. 349 */ 350 close(stdin_pipe[WRITE_PIPE]); 351 352 children++; 353 354 /* 355 * read output from the grandchild. it's stderr has been redirected to 356 * it's stdout, which has been redirected to our pipe. if there is any 357 * output, we'll be mailing it to the user whose crontab this is... 358 * when the grandchild exits, we'll get EOF. 359 */ 360 361 Debug(DPROC, ("[%d] child reading output from grandchild\n", getpid())) 362 363 /*local*/{ 364 register FILE *in = fdopen(stdout_pipe[READ_PIPE], "r"); 365 register int ch = getc(in); 366 367 if (in == NULL) { 368 warn("fdopen failed in child"); 369 _exit(ERROR_EXIT); 370 } 371 372 if (ch != EOF) { 373 register FILE *mail; 374 register int bytes = 1; 375 int status = 0; 376 377 Debug(DPROC|DEXT, 378 ("[%d] got data (%x:%c) from grandchild\n", 379 getpid(), ch, ch)) 380 381 /* get name of recipient. this is MAILTO if set to a 382 * valid local username; USER otherwise. 383 */ 384 if (mailto) { 385 /* MAILTO was present in the environment 386 */ 387 if (!*mailto) { 388 /* ... but it's empty. set to NULL 389 */ 390 mailto = NULL; 391 } 392 } else { 393 /* MAILTO not present, set to USER. 394 */ 395 mailto = usernm; 396 } 397 398 /* if we are supposed to be mailing, MAILTO will 399 * be non-NULL. only in this case should we set 400 * up the mail command and subjects and stuff... 401 */ 402 403 if (mailto) { 404 register char **env; 405 auto char mailcmd[MAX_COMMAND]; 406 auto char hostname[MAXHOSTNAMELEN]; 407 408 (void) gethostname(hostname, MAXHOSTNAMELEN); 409 (void) snprintf(mailcmd, sizeof(mailcmd), 410 MAILARGS, MAILCMD); 411 if (!(mail = cron_popen(mailcmd, "w", e))) { 412 warn("%s", MAILCMD); 413 (void) _exit(ERROR_EXIT); 414 } 415 fprintf(mail, "From: %s (Cron Daemon)\n", usernm); 416 fprintf(mail, "To: %s\n", mailto); 417 fprintf(mail, "Subject: Cron <%s@%s> %s\n", 418 usernm, first_word(hostname, "."), 419 e->cmd); 420 # if defined(MAIL_DATE) 421 fprintf(mail, "Date: %s\n", 422 arpadate(&TargetTime)); 423 # endif /* MAIL_DATE */ 424 for (env = e->envp; *env; env++) 425 fprintf(mail, "X-Cron-Env: <%s>\n", 426 *env); 427 fprintf(mail, "\n"); 428 429 /* this was the first char from the pipe 430 */ 431 putc(ch, mail); 432 } 433 434 /* we have to read the input pipe no matter whether 435 * we mail or not, but obviously we only write to 436 * mail pipe if we ARE mailing. 437 */ 438 439 while (EOF != (ch = getc(in))) { 440 bytes++; 441 if (mailto) 442 putc(ch, mail); 443 } 444 445 /* only close pipe if we opened it -- i.e., we're 446 * mailing... 447 */ 448 449 if (mailto) { 450 Debug(DPROC, ("[%d] closing pipe to mail\n", 451 getpid())) 452 /* Note: the pclose will probably see 453 * the termination of the grandchild 454 * in addition to the mail process, since 455 * it (the grandchild) is likely to exit 456 * after closing its stdout. 457 */ 458 status = cron_pclose(mail); 459 } 460 461 /* if there was output and we could not mail it, 462 * log the facts so the poor user can figure out 463 * what's going on. 464 */ 465 if (mailto && status) { 466 char buf[MAX_TEMPSTR]; 467 468 snprintf(buf, sizeof(buf), 469 "mailed %d byte%s of output but got status 0x%04x\n", 470 bytes, (bytes==1)?"":"s", 471 status); 472 log_it(usernm, getpid(), "MAIL", buf); 473 } 474 475 } /*if data from grandchild*/ 476 477 Debug(DPROC, ("[%d] got EOF from grandchild\n", getpid())) 478 479 fclose(in); /* also closes stdout_pipe[READ_PIPE] */ 480 } 481 482 /* wait for children to die. 483 */ 484 for (; children > 0; children--) 485 { 486 WAIT_T waiter; 487 PID_T pid; 488 489 Debug(DPROC, ("[%d] waiting for grandchild #%d to finish\n", 490 getpid(), children)) 491 pid = wait(&waiter); 492 if (pid < OK) { 493 Debug(DPROC, ("[%d] no more grandchildren--mail written?\n", 494 getpid())) 495 break; 496 } 497 Debug(DPROC, ("[%d] grandchild #%d finished, status=%04x", 498 getpid(), pid, WEXITSTATUS(waiter))) 499 if (WIFSIGNALED(waiter) && WCOREDUMP(waiter)) 500 Debug(DPROC, (", dumped core")) 501 Debug(DPROC, ("\n")) 502 } 503 } 504 505 506 static void 507 do_univ(user *u) 508 { 509 #if defined(sequent) 510 /* Dynix (Sequent) hack to put the user associated with 511 * the passed user structure into the ATT universe if 512 * necessary. We have to dig the gecos info out of 513 * the user's password entry to see if the magic 514 * "universe(att)" string is present. 515 */ 516 517 struct passwd *p; 518 char *s; 519 int i; 520 521 p = getpwuid(u->uid); 522 (void) endpwent(); 523 524 if (p == NULL) 525 return; 526 527 s = p->pw_gecos; 528 529 for (i = 0; i < 4; i++) 530 { 531 if ((s = strchr(s, ',')) == NULL) 532 return; 533 s++; 534 } 535 if (strcmp(s, "universe(att)")) 536 return; 537 538 (void) universe(U_ATT); 539 #endif 540 } 541