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  * $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 1.5 2004/03/10 18:27:26 dillon 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         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                 int escaped = FALSE;
 126                 int ch;
 127                 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                 FILE *out;
 298                 int need_newline = FALSE;
 299                 int escaped = FALSE;
 300                 int ch;
 301
 302                 out = fdopen(stdin_pipe[WRITE_PIPE], "w");
 303                 if (out == NULL) {
 304                         warn("fdopen failed in child2");
 305                         _exit(ERROR_EXIT);
 306                 }
 307
 308                 Debug(DPROC, ("[%d] child2 sending data to grandchild\n", getpid()))
 309
 310                 /* close the pipe we don't use, since we inherited it and
 311                  * are part of its reference count now.
 312                  */
 313                 close(stdout_pipe[READ_PIPE]);
 314
 315                 /* translation:
 316                  *      \% -> %
 317                  *      %  -> \n
 318                  *      \x -> \x        for all x != %
 319                  */
 320                 while ((ch = *input_data++)) {
 321                         if (escaped) {
 322                                 if (ch != '%')
 323                                         putc('\\', out);
 324                         } else {
 325                                 if (ch == '%')
 326                                         ch = '\n';
 327                         }
 328
 329                         if (!(escaped = (ch == '\\'))) {
 330                                 putc(ch, out);
 331                                 need_newline = (ch != '\n');
 332                         }
 333                 }
 334                 if (escaped)
 335                         putc('\\', out);
 336                 if (need_newline)
 337                         putc('\n', out);
 338
 339                 /* close the pipe, causing an EOF condition.  fclose causes
 340                  * stdin_pipe[WRITE_PIPE] to be closed, too.
 341                  */
 342                 fclose(out);
 343
 344                 Debug(DPROC, ("[%d] child2 done sending to grandchild\n", getpid()))
 345                 exit(0);
 346         }
 347
 348         /* close the pipe to the grandkiddie's stdin, since its wicked uncle
 349          * ernie back there has it open and will close it when he's done.
 350          */
 351         close(stdin_pipe[WRITE_PIPE]);
 352
 353         children++;
 354
 355         /*
 356          * read output from the grandchild.  it's stderr has been redirected to
 357          * it's stdout, which has been redirected to our pipe.  if there is any
 358          * output, we'll be mailing it to the user whose crontab this is...
 359          * when the grandchild exits, we'll get EOF.
 360          */
 361
 362         Debug(DPROC, ("[%d] child reading output from grandchild\n", getpid()))
 363
 364         /*local*/{
 365                 FILE *in;
 366                 int ch;
 367
 368                 in = fdopen(stdout_pipe[READ_PIPE], "r");
 369                 if (in == NULL) {
 370                         warn("fdopen failed in child");
 371                         _exit(ERROR_EXIT);
 372                 }
 373
 374                 ch = getc(in);
 375                 if (ch != EOF) {
 376                         FILE *mail;
 377                         int bytes = 1;
 378                         int status = 0;
 379
 380                         Debug(DPROC|DEXT,
 381                                 ("[%d] got data (%x:%c) from grandchild\n",
 382                                         getpid(), ch, ch))
 383
 384                         /* get name of recipient.  this is MAILTO if set to a
 385                          * valid local username; USER otherwise.
 386                          */
 387                         if (mailto) {
 388                                 /* MAILTO was present in the environment
 389                                  */
 390                                 if (!*mailto) {
 391                                         /* ... but it's empty. set to NULL
 392                                          */
 393                                         mailto = NULL;
 394                                 }
 395                         } else {
 396                                 /* MAILTO not present, set to USER.
 397                                  */
 398                                 mailto = usernm;
 399                         }
 400
 401                         /* if we are supposed to be mailing, MAILTO will
 402                          * be non-NULL.  only in this case should we set
 403                          * up the mail command and subjects and stuff...
 404                          */
 405
 406                         if (mailto) {
 407                                 char **env;
 408                                 char mailcmd[MAX_COMMAND];
 409                                 char hostname[MAXHOSTNAMELEN];
 410
 411                                 (void) gethostname(hostname, MAXHOSTNAMELEN);
 412                                 (void) snprintf(mailcmd, sizeof(mailcmd),
 413                                                MAILARGS, MAILCMD);
 414                                 if (!(mail = cron_popen(mailcmd, "w", e))) {
 415                                         warn("%s", MAILCMD);
 416                                         (void) _exit(ERROR_EXIT);
 417                                 }
 418                                 fprintf(mail, "From: %s (Cron Daemon)\n", usernm);
 419                                 fprintf(mail, "To: %s\n", mailto);
 420                                 fprintf(mail, "Subject: Cron <%s@%s> %s\n",
 421                                         usernm, first_word(hostname, "."),
 422                                         e->cmd);
 423 # if defined(MAIL_DATE)
 424                                 fprintf(mail, "Date: %s\n",
 425                                         arpadate(&TargetTime));
 426 # endif /* MAIL_DATE */
 427                                 for (env = e->envp;  *env;  env++)
 428                                         fprintf(mail, "X-Cron-Env: <%s>\n",
 429                                                 *env);
 430                                 fprintf(mail, "\n");
 431
 432                                 /* this was the first char from the pipe
 433                                  */
 434                                 putc(ch, mail);
 435                         }
 436
 437                         /* we have to read the input pipe no matter whether
 438                          * we mail or not, but obviously we only write to
 439                          * mail pipe if we ARE mailing.
 440                          */
 441
 442                         while (EOF != (ch = getc(in))) {
 443                                 bytes++;
 444                                 if (mailto)
 445                                         putc(ch, mail);
 446                         }
 447
 448                         /* only close pipe if we opened it -- i.e., we're
 449                          * mailing...
 450                          */
 451
 452                         if (mailto) {
 453                                 Debug(DPROC, ("[%d] closing pipe to mail\n",
 454                                         getpid()))
 455                                 /* Note: the pclose will probably see
 456                                  * the termination of the grandchild
 457                                  * in addition to the mail process, since
 458                                  * it (the grandchild) is likely to exit
 459                                  * after closing its stdout.
 460                                  */
 461                                 status = cron_pclose(mail);
 462                         }
 463
 464                         /* if there was output and we could not mail it,
 465                          * log the facts so the poor user can figure out
 466                          * what's going on.
 467                          */
 468                         if (mailto && status) {
 469                                 char buf[MAX_TEMPSTR];
 470
 471                                 snprintf(buf, sizeof(buf),
 472                         "mailed %d byte%s of output but got status 0x%04x\n",
 473                                         bytes, (bytes==1)?"":"s",
 474                                         status);
 475                                 log_it(usernm, getpid(), "MAIL", buf);
 476                         }
 477
 478                 } /*if data from grandchild*/
 479
 480                 Debug(DPROC, ("[%d] got EOF from grandchild\n", getpid()))
 481
 482                 fclose(in);     /* also closes stdout_pipe[READ_PIPE] */
 483         }
 484
 485         /* wait for children to die.
 486          */
 487         for (;  children > 0;  children--)
 488         {
 489                 WAIT_T          waiter;
 490                 PID_T           pid;
 491
 492                 Debug(DPROC, ("[%d] waiting for grandchild #%d to finish\n",
 493                         getpid(), children))
 494                 pid = wait(&waiter);
 495                 if (pid < OK) {
 496                         Debug(DPROC, ("[%d] no more grandchildren--mail written?\n",
 497                                 getpid()))
 498                         break;
 499                 }
 500                 Debug(DPROC, ("[%d] grandchild #%d finished, status=%04x",
 501                         getpid(), pid, WEXITSTATUS(waiter)))
 502                 if (WIFSIGNALED(waiter) && WCOREDUMP(waiter))
 503                         Debug(DPROC, (", dumped core"))
 504                 Debug(DPROC, ("\n"))
 505         }
 506 }
 507
 508
 509 static void
 510 do_univ(user *u)
 511 {
 512 #if defined(sequent)
 513 /* Dynix (Sequent) hack to put the user associated with
 514  * the passed user structure into the ATT universe if
 515  * necessary.  We have to dig the gecos info out of
 516  * the user's password entry to see if the magic
 517  * "universe(att)" string is present.
 518  */
 519
 520         struct  passwd  *p;
 521         char    *s;
 522         int     i;
 523
 524         p = getpwuid(u->uid);
 525         (void) endpwent();
 526
 527         if (p == NULL)
 528                 return;
 529
 530         s = p->pw_gecos;
 531
 532         for (i = 0; i < 4; i++)
 533         {
 534                 if ((s = strchr(s, ',')) == NULL)
 535                         return;
 536                 s++;
 537         }
 538         if (strcmp(s, "universe(att)"))
 539                 return;
 540
 541         (void) universe(U_ATT);
 542 #endif
 543 }