usr.sbin/cron/cron/do_command.c

   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         pipe(stdin_pipe);       /* child's stdin */
 165         pipe(stdout_pipe);      /* child's stdout */
 166
 167         /* since we are a forked process, we can diddle the command string
 168          * we were passed -- nobody else is going to use it again, right?
 169          *
 170          * if a % is present in the command, previous characters are the
 171          * command, and subsequent characters are the additional input to
 172          * the command.  Subsequent %'s will be transformed into newlines,
 173          * but that happens later.
 174          *
 175          * If there are escaped %'s, remove the escape character.
 176          */
 177         /*local*/{
 178                 register int escaped = FALSE;
 179                 register int ch;
 180                 register char *p;
 181
 182                 for (input_data = p = e->cmd; (ch = *input_data);
 183                      input_data++, p++) {
 184                         if (p != input_data)
 185                             *p = ch;
 186                         if (escaped) {
 187                                 if (ch == '%' || ch == '\\')
 188                                         *--p = ch;
 189                                 escaped = FALSE;
 190                                 continue;
 191                         }
 192                         if (ch == '\\') {
 193                                 escaped = TRUE;
 194                                 continue;
 195                         }
 196                         if (ch == '%') {
 197                                 *input_data++ = '\0';
 198                                 break;
 199                         }
 200                 }
 201                 *p = '\0';
 202         }
 203
 204         /* fork again, this time so we can exec the user's command.
 205          */
 206         switch (vfork()) {
 207         case -1:
 208                 log_it("CRON",getpid(),"error","can't vfork");
 209                 exit(ERROR_EXIT);
 210                 /*NOTREACHED*/
 211         case 0:
 212                 Debug(DPROC, ("[%d] grandchild process Vfork()'ed\n",
 213                               getpid()))
 214
 215                 if (e->uid == ROOT_UID)
 216                         Jitter = RootJitter;
 217                 if (Jitter != 0) {
 218                         srandom(getpid());
 219                         sleep(random() % Jitter);
 220                 }
 221
 222                 /* write a log message.  we've waited this long to do it
 223                  * because it was not until now that we knew the PID that
 224                  * the actual user command shell was going to get and the
 225                  * PID is part of the log message.
 226                  */
 227                 /*local*/{
 228                         char *x = mkprints((u_char *)e->cmd, strlen(e->cmd));
 229
 230                         log_it(usernm, getpid(), "CMD", x);
 231                         free(x);
 232                 }
 233
 234                 /* that's the last thing we'll log.  close the log files.
 235                  */
 236 #ifdef SYSLOG
 237                 closelog();
 238 #endif
 239
 240                 /* get new pgrp, void tty, etc.
 241                  */
 242                 (void) setsid();
 243
 244                 /* close the pipe ends that we won't use.  this doesn't affect
 245                  * the parent, who has to read and write them; it keeps the
 246                  * kernel from recording us as a potential client TWICE --
 247                  * which would keep it from sending SIGPIPE in otherwise
 248                  * appropriate circumstances.
 249                  */
 250                 close(stdin_pipe[WRITE_PIPE]);
 251                 close(stdout_pipe[READ_PIPE]);
 252
 253                 /* grandchild process.  make std{in,out} be the ends of
 254                  * pipes opened by our daddy; make stderr go to stdout.
 255                  */
 256                 close(STDIN);   dup2(stdin_pipe[READ_PIPE], STDIN);
 257                 close(STDOUT);  dup2(stdout_pipe[WRITE_PIPE], STDOUT);
 258                 close(STDERR);  dup2(STDOUT, STDERR);
 259
 260                 /* close the pipes we just dup'ed.  The resources will remain.
 261                  */
 262                 close(stdin_pipe[READ_PIPE]);
 263                 close(stdout_pipe[WRITE_PIPE]);
 264
 265                 /* set our login universe.  Do this in the grandchild
 266                  * so that the child can invoke /usr/lib/sendmail
 267                  * without surprises.
 268                  */
 269                 do_univ(u);
 270
 271 # if defined(LOGIN_CAP)
 272                 /* Set user's entire context, but skip the environment
 273                  * as cron provides a separate interface for this
 274                  */
 275                 if ((pwd = getpwnam(usernm)) == NULL)
 276                         pwd = getpwuid(e->uid);
 277                 lc = NULL;
 278                 if (pwd != NULL) {
 279                         pwd->pw_gid = e->gid;
 280                         if (e->class != NULL)
 281                                 lc = login_getclass(e->class);
 282                 }
 283                 if (pwd &&
 284                     setusercontext(lc, pwd, e->uid,
 285                             LOGIN_SETALL & ~(LOGIN_SETPATH|LOGIN_SETENV)) == 0)
 286                         (void) endpwent();
 287                 else {
 288                         /* fall back to the old method */
 289                         (void) endpwent();
 290 # endif
 291                         /* set our directory, uid and gid.  Set gid first,
 292                          * since once we set uid, we've lost root privileges.
 293                          */
 294                         if (setgid(e->gid) != 0) {
 295                                 log_it(usernm, getpid(),
 296                                     "error", "setgid failed");
 297                                 exit(ERROR_EXIT);
 298                         }
 299 # if defined(BSD)
 300                         if (initgroups(usernm, e->gid) != 0) {
 301                                 log_it(usernm, getpid(),
 302                                     "error", "initgroups failed");
 303                                 exit(ERROR_EXIT);
 304                         }
 305 # endif
 306                         if (setlogin(usernm) != 0) {
 307                                 log_it(usernm, getpid(),
 308                                     "error", "setlogin failed");
 309                                 exit(ERROR_EXIT);
 310                         }
 311                         if (setuid(e->uid) != 0) {
 312                                 log_it(usernm, getpid(),
 313                                     "error", "setuid failed");
 314                                 exit(ERROR_EXIT);
 315                         }
 316                         /* we aren't root after this..*/
 317 #if defined(LOGIN_CAP)
 318                 }
 319                 if (lc != NULL)
 320                         login_close(lc);
 321 #endif
 322                 chdir(env_get("HOME", e->envp));
 323
 324                 /* exec the command.
 325                  */
 326                 {
 327                         char    *shell = env_get("SHELL", e->envp);
 328
 329 # if DEBUGGING
 330                         if (DebugFlags & DTEST) {
 331                                 fprintf(stderr,
 332                                 "debug DTEST is on, not exec'ing command.\n");
 333                                 fprintf(stderr,
 334                                 "\tcmd='%s' shell='%s'\n", e->cmd, shell);
 335                                 _exit(OK_EXIT);
 336                         }
 337 # endif /*DEBUGGING*/
 338                         execle(shell, shell, "-c", e->cmd, (char *)0, e->envp);
 339                         warn("execl: couldn't exec `%s'", shell);
 340                         _exit(ERROR_EXIT);
 341                 }
 342                 break;
 343         default:
 344                 /* parent process */
 345                 break;
 346         }
 347
 348         children++;
 349
 350         /* middle process, child of original cron, parent of process running
 351          * the user's command.
 352          */
 353
 354         Debug(DPROC, ("[%d] child continues, closing pipes\n", getpid()))
 355
 356         /* close the ends of the pipe that will only be referenced in the
 357          * grandchild process...
 358          */
 359         close(stdin_pipe[READ_PIPE]);
 360         close(stdout_pipe[WRITE_PIPE]);
 361
 362         /*
 363          * write, to the pipe connected to child's stdin, any input specified
 364          * after a % in the crontab entry.  while we copy, convert any
 365          * additional %'s to newlines.  when done, if some characters were
 366          * written and the last one wasn't a newline, write a newline.
 367          *
 368          * Note that if the input data won't fit into one pipe buffer (2K
 369          * or 4K on most BSD systems), and the child doesn't read its stdin,
 370          * we would block here.  thus we must fork again.
 371          */
 372
 373         if (*input_data && fork() == 0) {
 374                 register FILE   *out = fdopen(stdin_pipe[WRITE_PIPE], "w");
 375                 register int    need_newline = FALSE;
 376                 register int    escaped = FALSE;
 377                 register int    ch;
 378
 379                 if (out == NULL) {
 380                         warn("fdopen failed in child2");
 381                         _exit(ERROR_EXIT);
 382                 }
 383
 384                 Debug(DPROC, ("[%d] child2 sending data to grandchild\n", getpid()))
 385
 386                 /* close the pipe we don't use, since we inherited it and
 387                  * are part of its reference count now.
 388                  */
 389                 close(stdout_pipe[READ_PIPE]);
 390
 391                 /* translation:
 392                  *      \% -> %
 393                  *      %  -> \n
 394                  *      \x -> \x        for all x != %
 395                  */
 396                 while ((ch = *input_data++)) {
 397                         if (escaped) {
 398                                 if (ch != '%')
 399                                         putc('\\', out);
 400                         } else {
 401                                 if (ch == '%')
 402                                         ch = '\n';
 403                         }
 404
 405                         if (!(escaped = (ch == '\\'))) {
 406                                 putc(ch, out);
 407                                 need_newline = (ch != '\n');
 408                         }
 409                 }
 410                 if (escaped)
 411                         putc('\\', out);
 412                 if (need_newline)
 413                         putc('\n', out);
 414
 415                 /* close the pipe, causing an EOF condition.  fclose causes
 416                  * stdin_pipe[WRITE_PIPE] to be closed, too.
 417                  */
 418                 fclose(out);
 419
 420                 Debug(DPROC, ("[%d] child2 done sending to grandchild\n", getpid()))
 421                 exit(0);
 422         }
 423
 424         /* close the pipe to the grandkiddie's stdin, since its wicked uncle
 425          * ernie back there has it open and will close it when he's done.
 426          */
 427         close(stdin_pipe[WRITE_PIPE]);
 428
 429         children++;
 430
 431         /*
 432          * read output from the grandchild.  it's stderr has been redirected to
 433          * it's stdout, which has been redirected to our pipe.  if there is any
 434          * output, we'll be mailing it to the user whose crontab this is...
 435          * when the grandchild exits, we'll get EOF.
 436          */
 437
 438         Debug(DPROC, ("[%d] child reading output from grandchild\n", getpid()))
 439
 440         /*local*/{
 441                 register FILE   *in = fdopen(stdout_pipe[READ_PIPE], "r");
 442                 register int    ch;
 443
 444                 if (in == NULL) {
 445                         warn("fdopen failed in child");
 446                         _exit(ERROR_EXIT);
 447                 }
 448
 449                 ch = getc(in);
 450                 if (ch != EOF) {
 451                         register FILE   *mail;
 452                         register int    bytes = 1;
 453                         int             status = 0;
 454
 455                         Debug(DPROC|DEXT,
 456                                 ("[%d] got data (%x:%c) from grandchild\n",
 457                                         getpid(), ch, ch))
 458
 459                         /* get name of recipient.  this is MAILTO if set to a
 460                          * valid local username; USER otherwise.
 461                          */
 462                         if (mailto == NULL) {
 463                                 /* MAILTO not present, set to USER,
 464                                  * unless globally overriden.
 465                                  */
 466                                 if (defmailto)
 467                                         mailto = defmailto;
 468                                 else
 469                                         mailto = usernm;
 470                         }
 471                         if (mailto && *mailto == '\0')
 472                                 mailto = NULL;
 473
 474                         /* if we are supposed to be mailing, MAILTO will
 475                          * be non-NULL.  only in this case should we set
 476                          * up the mail command and subjects and stuff...
 477                          */
 478
 479                         if (mailto) {
 480                                 register char   **env;
 481                                 auto char       mailcmd[MAX_COMMAND];
 482                                 auto char       hostname[MAXHOSTNAMELEN];
 483
 484                                 (void) gethostname(hostname, MAXHOSTNAMELEN);
 485                                 (void) snprintf(mailcmd, sizeof(mailcmd),
 486                                                MAILARGS, MAILCMD);
 487                                 if (!(mail = cron_popen(mailcmd, "w", e))) {
 488                                         warn("%s", MAILCMD);
 489                                         (void) _exit(ERROR_EXIT);
 490                                 }
 491                                 fprintf(mail, "From: %s (Cron Daemon)\n", usernm);
 492                                 fprintf(mail, "To: %s\n", mailto);
 493                                 fprintf(mail, "Subject: Cron <%s@%s> %s\n",
 494                                         usernm, first_word(hostname, "."),
 495                                         e->cmd);
 496 # if defined(MAIL_DATE)
 497                                 fprintf(mail, "Date: %s\n",
 498                                         arpadate(&TargetTime));
 499 # endif /* MAIL_DATE */
 500                                 for (env = e->envp;  *env;  env++)
 501                                         fprintf(mail, "X-Cron-Env: <%s>\n",
 502                                                 *env);
 503                                 fprintf(mail, "\n");
 504
 505                                 /* this was the first char from the pipe
 506                                  */
 507                                 putc(ch, mail);
 508                         }
 509
 510                         /* we have to read the input pipe no matter whether
 511                          * we mail or not, but obviously we only write to
 512                          * mail pipe if we ARE mailing.
 513                          */
 514
 515                         while (EOF != (ch = getc(in))) {
 516                                 bytes++;
 517                                 if (mailto)
 518                                         putc(ch, mail);
 519                         }
 520
 521                         /* only close pipe if we opened it -- i.e., we're
 522                          * mailing...
 523                          */
 524
 525                         if (mailto) {
 526                                 Debug(DPROC, ("[%d] closing pipe to mail\n",
 527                                         getpid()))
 528                                 /* Note: the pclose will probably see
 529                                  * the termination of the grandchild
 530                                  * in addition to the mail process, since
 531                                  * it (the grandchild) is likely to exit
 532                                  * after closing its stdout.
 533                                  */
 534                                 status = cron_pclose(mail);
 535                         }
 536
 537                         /* if there was output and we could not mail it,
 538                          * log the facts so the poor user can figure out
 539                          * what's going on.
 540                          */
 541                         if (mailto && status) {
 542                                 char buf[MAX_TEMPSTR];
 543
 544                                 snprintf(buf, sizeof(buf),
 545                         "mailed %d byte%s of output but got status 0x%04x\n",
 546                                         bytes, (bytes==1)?"":"s",
 547                                         status);
 548                                 log_it(usernm, getpid(), "MAIL", buf);
 549                         }
 550
 551                 } /*if data from grandchild*/
 552
 553                 Debug(DPROC, ("[%d] got EOF from grandchild\n", getpid()))
 554
 555                 fclose(in);     /* also closes stdout_pipe[READ_PIPE] */
 556         }
 557
 558         /* wait for children to die.
 559          */
 560         for (;  children > 0;  children--)
 561         {
 562                 WAIT_T          waiter;
 563                 PID_T           pid;
 564
 565                 Debug(DPROC, ("[%d] waiting for grandchild #%d to finish\n",
 566                         getpid(), children))
 567                 pid = wait(&waiter);
 568                 if (pid < OK) {
 569                         Debug(DPROC, ("[%d] no more grandchildren--mail written?\n",
 570                                 getpid()))
 571                         break;
 572                 }
 573                 Debug(DPROC, ("[%d] grandchild #%d finished, status=%04x",
 574                         getpid(), pid, WEXITSTATUS(waiter)))
 575                 if (WIFSIGNALED(waiter) && WCOREDUMP(waiter))
 576                         Debug(DPROC, (", dumped core"))
 577                 Debug(DPROC, ("\n"))
 578         }
 579 }
 580
 581
 582 static void
 583 do_univ(u)
 584         user    *u;
 585 {
 586 #if defined(sequent)
 587 /* Dynix (Sequent) hack to put the user associated with
 588  * the passed user structure into the ATT universe if
 589  * necessary.  We have to dig the gecos info out of
 590  * the user's password entry to see if the magic
 591  * "universe(att)" string is present.
 592  */
 593
 594         struct  passwd  *p;
 595         char    *s;
 596         int     i;
 597
 598         p = getpwuid(u->uid);
 599         (void) endpwent();
 600
 601         if (p == NULL)
 602                 return;
 603
 604         s = p->pw_gecos;
 605
 606         for (i = 0; i < 4; i++)
 607         {
 608                 if ((s = strchr(s, ',')) == NULL)
 609                         return;
 610                 s++;
 611         }
 612         if (strcmp(s, "universe(att)"))
 613                 return;
 614
 615         (void) universe(U_ATT);
 616 #endif
 617 }