do_command.c revision 62359
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) 19static const char rcsid[] = 20 "$FreeBSD: head/usr.sbin/cron/cron/do_command.c 62359 2000-07-01 21:25:33Z ache $"; 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 36 37static void child_process __P((entry *, user *)), 38 do_univ __P((user *)); 39 40 41void 42do_command(e, u) 43 entry *e; 44 user *u; 45{ 46 Debug(DPROC, ("[%d] do_command(%s, (%s,%d,%d))\n", 47 getpid(), e->cmd, u->name, e->uid, e->gid)) 48 49 /* fork to become asynchronous -- parent process is done immediately, 50 * and continues to run the normal cron code, which means return to 51 * tick(). the child and grandchild don't leave this function, alive. 52 * 53 * vfork() is unsuitable, since we have much to do, and the parent 54 * needs to be able to run off and fork other processes. 55 */ 56 switch (fork()) { 57 case -1: 58 log_it("CRON",getpid(),"error","can't fork"); 59 break; 60 case 0: 61 /* child process */ 62 acquire_daemonlock(1); 63 child_process(e, u); 64 Debug(DPROC, ("[%d] child process done, exiting\n", getpid())) 65 _exit(OK_EXIT); 66 break; 67 default: 68 /* parent process */ 69 break; 70 } 71 Debug(DPROC, ("[%d] main process returning to work\n", getpid())) 72} 73 74 75static void 76child_process(e, u) 77 entry *e; 78 user *u; 79{ 80 int stdin_pipe[2], stdout_pipe[2]; 81 register char *input_data; 82 char *usernm, *mailto; 83 int children = 0; 84# if defined(LOGIN_CAP) 85 struct passwd *pwd; 86 login_cap_t *lc; 87# endif 88 89 Debug(DPROC, ("[%d] child_process('%s')\n", getpid(), e->cmd)) 90 91 /* mark ourselves as different to PS command watchers by upshifting 92 * our program name. This has no effect on some kernels. 93 */ 94 /*local*/{ 95 register char *pch; 96 97 for (pch = ProgramName; *pch; pch++) 98 *pch = MkUpper(*pch); 99 } 100 101 /* discover some useful and important environment settings 102 */ 103 usernm = env_get("LOGNAME", e->envp); 104 mailto = env_get("MAILTO", e->envp); 105 106#ifdef USE_SIGCHLD 107 /* our parent is watching for our death by catching SIGCHLD. we 108 * do not care to watch for our children's deaths this way -- we 109 * use wait() explictly. so we have to disable the signal (which 110 * was inherited from the parent). 111 */ 112 (void) signal(SIGCHLD, SIG_DFL); 113#else 114 /* on system-V systems, we are ignoring SIGCLD. we have to stop 115 * ignoring it now or the wait() in cron_pclose() won't work. 116 * because of this, we have to wait() for our children here, as well. 117 */ 118 (void) signal(SIGCLD, SIG_DFL); 119#endif /*BSD*/ 120 121 /* create some pipes to talk to our future child 122 */ 123 pipe(stdin_pipe); /* child's stdin */ 124 pipe(stdout_pipe); /* child's stdout */ 125 126 /* since we are a forked process, we can diddle the command string 127 * we were passed -- nobody else is going to use it again, right? 128 * 129 * if a % is present in the command, previous characters are the 130 * command, and subsequent characters are the additional input to 131 * the command. Subsequent %'s will be transformed into newlines, 132 * but that happens later. 133 * 134 * If there are escaped %'s, remove the escape character. 135 */ 136 /*local*/{ 137 register int escaped = FALSE; 138 register int ch; 139 register char *p; 140 141 for (input_data = p = e->cmd; (ch = *input_data); 142 input_data++, p++) { 143 if (p != input_data) 144 *p = ch; 145 if (escaped) { 146 if (ch == '%' || ch == '\\') 147 *--p = ch; 148 escaped = FALSE; 149 continue; 150 } 151 if (ch == '\\') { 152 escaped = TRUE; 153 continue; 154 } 155 if (ch == '%') { 156 *input_data++ = '\0'; 157 break; 158 } 159 } 160 *p = '\0'; 161 } 162 163 /* fork again, this time so we can exec the user's command. 164 */ 165 switch (vfork()) { 166 case -1: 167 log_it("CRON",getpid(),"error","can't vfork"); 168 exit(ERROR_EXIT); 169 /*NOTREACHED*/ 170 case 0: 171 Debug(DPROC, ("[%d] grandchild process Vfork()'ed\n", 172 getpid())) 173 174 /* write a log message. we've waited this long to do it 175 * because it was not until now that we knew the PID that 176 * the actual user command shell was going to get and the 177 * PID is part of the log message. 178 */ 179 /*local*/{ 180 char *x = mkprints((u_char *)e->cmd, strlen(e->cmd)); 181 182 log_it(usernm, getpid(), "CMD", x); 183 free(x); 184 } 185 186 /* that's the last thing we'll log. close the log files. 187 */ 188#ifdef SYSLOG 189 closelog(); 190#endif 191 192 /* get new pgrp, void tty, etc. 193 */ 194 (void) setsid(); 195 196 /* close the pipe ends that we won't use. this doesn't affect 197 * the parent, who has to read and write them; it keeps the 198 * kernel from recording us as a potential client TWICE -- 199 * which would keep it from sending SIGPIPE in otherwise 200 * appropriate circumstances. 201 */ 202 close(stdin_pipe[WRITE_PIPE]); 203 close(stdout_pipe[READ_PIPE]); 204 205 /* grandchild process. make std{in,out} be the ends of 206 * pipes opened by our daddy; make stderr go to stdout. 207 */ 208 close(STDIN); dup2(stdin_pipe[READ_PIPE], STDIN); 209 close(STDOUT); dup2(stdout_pipe[WRITE_PIPE], STDOUT); 210 close(STDERR); dup2(STDOUT, STDERR); 211 212 /* close the pipes we just dup'ed. The resources will remain. 213 */ 214 close(stdin_pipe[READ_PIPE]); 215 close(stdout_pipe[WRITE_PIPE]); 216 217 /* set our login universe. Do this in the grandchild 218 * so that the child can invoke /usr/lib/sendmail 219 * without surprises. 220 */ 221 do_univ(u); 222 223# if defined(LOGIN_CAP) 224 /* Set user's entire context, but skip the environment 225 * as cron provides a separate interface for this 226 */ 227 if ((pwd = getpwnam(usernm)) == NULL) 228 pwd = getpwuid(e->uid); 229 lc = NULL; 230 if (pwd != NULL) { 231 pwd->pw_gid = e->gid; 232 if (e->class != NULL) 233 lc = login_getclass(e->class); 234 } 235 if (pwd && 236 setusercontext(lc, pwd, e->uid, 237 LOGIN_SETALL & ~(LOGIN_SETPATH|LOGIN_SETENV)) == 0) 238 (void) endpwent(); 239 else { 240 /* fall back to the old method */ 241 (void) endpwent(); 242# endif 243 /* set our directory, uid and gid. Set gid first, 244 * since once we set uid, we've lost root privledges. 245 */ 246 setgid(e->gid); 247# if defined(BSD) 248 initgroups(usernm, e->gid); 249# endif 250 setlogin(usernm); 251 setuid(e->uid); /* we aren't root after this..*/ 252#if defined(LOGIN_CAP) 253 } 254#endif 255 chdir(env_get("HOME", e->envp)); 256 257 /* exec the command. 258 */ 259 { 260 char *shell = env_get("SHELL", e->envp); 261 262# if DEBUGGING 263 if (DebugFlags & DTEST) { 264 fprintf(stderr, 265 "debug DTEST is on, not exec'ing command.\n"); 266 fprintf(stderr, 267 "\tcmd='%s' shell='%s'\n", e->cmd, shell); 268 _exit(OK_EXIT); 269 } 270# endif /*DEBUGGING*/ 271 execle(shell, shell, "-c", e->cmd, (char *)0, e->envp); 272 warn("execl: couldn't exec `%s'", shell); 273 _exit(ERROR_EXIT); 274 } 275 break; 276 default: 277 /* parent process */ 278 break; 279 } 280 281 children++; 282 283 /* middle process, child of original cron, parent of process running 284 * the user's command. 285 */ 286 287 Debug(DPROC, ("[%d] child continues, closing pipes\n", getpid())) 288 289 /* close the ends of the pipe that will only be referenced in the 290 * grandchild process... 291 */ 292 close(stdin_pipe[READ_PIPE]); 293 close(stdout_pipe[WRITE_PIPE]); 294 295 /* 296 * write, to the pipe connected to child's stdin, any input specified 297 * after a % in the crontab entry. while we copy, convert any 298 * additional %'s to newlines. when done, if some characters were 299 * written and the last one wasn't a newline, write a newline. 300 * 301 * Note that if the input data won't fit into one pipe buffer (2K 302 * or 4K on most BSD systems), and the child doesn't read its stdin, 303 * we would block here. thus we must fork again. 304 */ 305 306 if (*input_data && fork() == 0) { 307 register FILE *out = fdopen(stdin_pipe[WRITE_PIPE], "w"); 308 register int need_newline = FALSE; 309 register int escaped = FALSE; 310 register int ch; 311 312 if (out == NULL) { 313 warn("fdopen failed in child2"); 314 _exit(ERROR_EXIT); 315 } 316 317 Debug(DPROC, ("[%d] child2 sending data to grandchild\n", getpid())) 318 319 /* close the pipe we don't use, since we inherited it and 320 * are part of its reference count now. 321 */ 322 close(stdout_pipe[READ_PIPE]); 323 324 /* translation: 325 * \% -> % 326 * % -> \n 327 * \x -> \x for all x != % 328 */ 329 while ((ch = *input_data++)) { 330 if (escaped) { 331 if (ch != '%') 332 putc('\\', out); 333 } else { 334 if (ch == '%') 335 ch = '\n'; 336 } 337 338 if (!(escaped = (ch == '\\'))) { 339 putc(ch, out); 340 need_newline = (ch != '\n'); 341 } 342 } 343 if (escaped) 344 putc('\\', out); 345 if (need_newline) 346 putc('\n', out); 347 348 /* close the pipe, causing an EOF condition. fclose causes 349 * stdin_pipe[WRITE_PIPE] to be closed, too. 350 */ 351 fclose(out); 352 353 Debug(DPROC, ("[%d] child2 done sending to grandchild\n", getpid())) 354 exit(0); 355 } 356 357 /* close the pipe to the grandkiddie's stdin, since its wicked uncle 358 * ernie back there has it open and will close it when he's done. 359 */ 360 close(stdin_pipe[WRITE_PIPE]); 361 362 children++; 363 364 /* 365 * read output from the grandchild. it's stderr has been redirected to 366 * it's stdout, which has been redirected to our pipe. if there is any 367 * output, we'll be mailing it to the user whose crontab this is... 368 * when the grandchild exits, we'll get EOF. 369 */ 370 371 Debug(DPROC, ("[%d] child reading output from grandchild\n", getpid())) 372 373 /*local*/{ 374 register FILE *in = fdopen(stdout_pipe[READ_PIPE], "r"); 375 register int ch = getc(in); 376 377 if (in == NULL) { 378 warn("fdopen failed in child"); 379 _exit(ERROR_EXIT); 380 } 381 382 if (ch != EOF) { 383 register FILE *mail; 384 register int bytes = 1; 385 int status = 0; 386 387 Debug(DPROC|DEXT, 388 ("[%d] got data (%x:%c) from grandchild\n", 389 getpid(), ch, ch)) 390 391 /* get name of recipient. this is MAILTO if set to a 392 * valid local username; USER otherwise. 393 */ 394 if (mailto) { 395 /* MAILTO was present in the environment 396 */ 397 if (!*mailto) { 398 /* ... but it's empty. set to NULL 399 */ 400 mailto = NULL; 401 } 402 } else { 403 /* MAILTO not present, set to USER. 404 */ 405 mailto = usernm; 406 } 407 408 /* if we are supposed to be mailing, MAILTO will 409 * be non-NULL. only in this case should we set 410 * up the mail command and subjects and stuff... 411 */ 412 413 if (mailto) { 414 register char **env; 415 auto char mailcmd[MAX_COMMAND]; 416 auto char hostname[MAXHOSTNAMELEN]; 417 418 (void) gethostname(hostname, MAXHOSTNAMELEN); 419 (void) snprintf(mailcmd, sizeof(mailcmd), 420 MAILARGS, MAILCMD); 421 if (!(mail = cron_popen(mailcmd, "w"))) { 422 warn("%s", MAILCMD); 423 (void) _exit(ERROR_EXIT); 424 } 425 fprintf(mail, "From: root (Cron Daemon)\n"); 426 fprintf(mail, "To: %s\n", mailto); 427 fprintf(mail, "Subject: Cron <%s@%s> %s\n", 428 usernm, first_word(hostname, "."), 429 e->cmd); 430# if defined(MAIL_DATE) 431 fprintf(mail, "Date: %s\n", 432 arpadate(&TargetTime)); 433# endif /* MAIL_DATE */ 434 for (env = e->envp; *env; env++) 435 fprintf(mail, "X-Cron-Env: <%s>\n", 436 *env); 437 fprintf(mail, "\n"); 438 439 /* this was the first char from the pipe 440 */ 441 putc(ch, mail); 442 } 443 444 /* we have to read the input pipe no matter whether 445 * we mail or not, but obviously we only write to 446 * mail pipe if we ARE mailing. 447 */ 448 449 while (EOF != (ch = getc(in))) { 450 bytes++; 451 if (mailto) 452 putc(ch, mail); 453 } 454 455 /* only close pipe if we opened it -- i.e., we're 456 * mailing... 457 */ 458 459 if (mailto) { 460 Debug(DPROC, ("[%d] closing pipe to mail\n", 461 getpid())) 462 /* Note: the pclose will probably see 463 * the termination of the grandchild 464 * in addition to the mail process, since 465 * it (the grandchild) is likely to exit 466 * after closing its stdout. 467 */ 468 status = cron_pclose(mail); 469 } 470 471 /* if there was output and we could not mail it, 472 * log the facts so the poor user can figure out 473 * what's going on. 474 */ 475 if (mailto && status) { 476 char buf[MAX_TEMPSTR]; 477 478 snprintf(buf, sizeof(buf), 479 "mailed %d byte%s of output but got status 0x%04x\n", 480 bytes, (bytes==1)?"":"s", 481 status); 482 log_it(usernm, getpid(), "MAIL", buf); 483 } 484 485 } /*if data from grandchild*/ 486 487 Debug(DPROC, ("[%d] got EOF from grandchild\n", getpid())) 488 489 fclose(in); /* also closes stdout_pipe[READ_PIPE] */ 490 } 491 492 /* wait for children to die. 493 */ 494 for (; children > 0; children--) 495 { 496 WAIT_T waiter; 497 PID_T pid; 498 499 Debug(DPROC, ("[%d] waiting for grandchild #%d to finish\n", 500 getpid(), children)) 501 pid = wait(&waiter); 502 if (pid < OK) { 503 Debug(DPROC, ("[%d] no more grandchildren--mail written?\n", 504 getpid())) 505 break; 506 } 507 Debug(DPROC, ("[%d] grandchild #%d finished, status=%04x", 508 getpid(), pid, WEXITSTATUS(waiter))) 509 if (WIFSIGNALED(waiter) && WCOREDUMP(waiter)) 510 Debug(DPROC, (", dumped core")) 511 Debug(DPROC, ("\n")) 512 } 513} 514 515 516static void 517do_univ(u) 518 user *u; 519{ 520#if defined(sequent) 521/* Dynix (Sequent) hack to put the user associated with 522 * the passed user structure into the ATT universe if 523 * necessary. We have to dig the gecos info out of 524 * the user's password entry to see if the magic 525 * "universe(att)" string is present. 526 */ 527 528 struct passwd *p; 529 char *s; 530 int i; 531 532 p = getpwuid(u->uid); 533 (void) endpwent(); 534 535 if (p == NULL) 536 return; 537 538 s = p->pw_gecos; 539 540 for (i = 0; i < 4; i++) 541 { 542 if ((s = strchr(s, ',')) == NULL) 543 return; 544 s++; 545 } 546 if (strcmp(s, "universe(att)")) 547 return; 548 549 (void) universe(U_ATT); 550#endif 551} 552