src/main/exec.c

   1 /*
   2  * exec.c       Execute external programs.
   3  *
   4  * Version:     $Id$
   5  *
   6  *   This program is free software; you can redistribute it and/or modify
   7  *   it under the terms of the GNU General Public License as published by
   8  *   the Free Software Foundation; either version 2 of the License, or
   9  *   (at your option) any later version.
  10  *
  11  *   This program is distributed in the hope that it will be useful,
  12  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  *   GNU General Public License for more details.
  15  *
  16  *   You should have received a copy of the GNU General Public License
  17  *   along with this program; if not, write to the Free Software
  18  *   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
  19  *
  20  * Copyright 2000-2004,2006  The FreeRADIUS server project
  21  */
  22
  23 #include <freeradius-devel/ident.h>
  24 RCSID("$Id$")
  25
  26 #include <freeradius-devel/radiusd.h>
  27 #include <freeradius-devel/rad_assert.h>
  28
  29 #include <sys/file.h>
  30
  31 #include <fcntl.h>
  32 #include <ctype.h>
  33 #include <signal.h>
  34
  35 #ifdef HAVE_SYS_WAIT_H
  36 #       include <sys/wait.h>
  37 #endif
  38 #ifndef WEXITSTATUS
  39 #       define WEXITSTATUS(stat_val) ((unsigned)(stat_val) >> 8)
  40 #endif
  41 #ifndef WIFEXITED
  42 #       define WIFEXITED(stat_val) (((stat_val) & 255) == 0)
  43 #endif
  44
  45 #define MAX_ARGV (256)
  46
  47 #define USEC 1000000
  48 static void tv_sub(struct timeval *end, struct timeval *start,
  49                    struct timeval *elapsed)
  50 {
  51         elapsed->tv_sec = end->tv_sec - start->tv_sec;
  52         if (elapsed->tv_sec > 0) {
  53                 elapsed->tv_sec--;
  54                 elapsed->tv_usec = USEC;
  55         } else {
  56                 elapsed->tv_usec = 0;
  57         }
  58         elapsed->tv_usec += end->tv_usec;
  59         elapsed->tv_usec -= start->tv_usec;
  60
  61         if (elapsed->tv_usec >= USEC) {
  62                 elapsed->tv_usec -= USEC;
  63                 elapsed->tv_sec++;
  64         }
  65 }
  66
  67
  68 /*
  69  *      Execute a program on successful authentication.
  70  *      Return 0 if exec_wait == 0.
  71  *      Return the exit code of the called program if exec_wait != 0.
  72  *      Return -1 on fork/other errors in the parent process.
  73  */
  74 int radius_exec_program(const char *cmd, REQUEST *request,
  75                         int exec_wait,
  76                         char *user_msg, int msg_len,
  77                         VALUE_PAIR *input_pairs,
  78                         VALUE_PAIR **output_pairs,
  79                         int shell_escape)
  80 {
  81         VALUE_PAIR *vp;
  82         char mycmd[1024];
  83         const char *from;
  84         char *p, *to;
  85         int pd[2];
  86         pid_t pid, child_pid;
  87         int argc = -1;
  88         int comma = 0;
  89         int status;
  90         int i;
  91         int n, left, done;
  92         char *argv[MAX_ARGV];
  93         char answer[4096];
  94         char argv_buf[4096];
  95 #define MAX_ENVP 1024
  96         char *envp[MAX_ENVP];
  97         struct timeval start;
  98 #ifdef O_NONBLOCK
  99         int nonblock = TRUE;
 100 #endif
 101
 102         if (user_msg) *user_msg = '\0';
 103         if (output_pairs) *output_pairs = NULL;
 104
 105         if (strlen(cmd) > (sizeof(mycmd) - 1)) {
 106                 radlog(L_ERR|L_CONS, "Command line is too long");
 107                 return -1;
 108         }
 109
 110         /*
 111          *      Check for bad escapes.
 112          */
 113         if (cmd[strlen(cmd) - 1] == '\\') {
 114                 radlog(L_ERR|L_CONS, "Command line has final backslash, without a following character");
 115                 return -1;
 116         }
 117
 118         strlcpy(mycmd, cmd, sizeof(mycmd));
 119
 120         /*
 121          *      Split the string into argv's BEFORE doing radius_xlat...
 122          */
 123         from = cmd;
 124         to = mycmd;
 125         argc = 0;
 126         while (*from) {
 127                 int length;
 128
 129                 /*
 130                  *      Skip spaces.
 131                  */
 132                 if ((*from == ' ') || (*from == '\t')) {
 133                         from++;
 134                         continue;
 135                 }
 136
 137                 argv[argc] = to;
 138                 argc++;
 139
 140                 if (argc >= (MAX_ARGV - 1)) break;
 141
 142                 /*
 143                  *      Copy the argv over to our buffer.
 144                  */
 145                 while (*from && (*from != ' ') && (*from != '\t')) {
 146                         if (to >= mycmd + sizeof(mycmd) - 1) {
 147                                 return -1; /* ran out of space */
 148                         }
 149
 150                         switch (*from) {
 151                         case '"':
 152                         case '\'':
 153                                 length = rad_copy_string(to, from);
 154                                 if (length < 0) {
 155                                         radlog(L_ERR|L_CONS, "Invalid string passed as argument for external program");
 156                                         return -1;
 157                                 }
 158                                 from += length;
 159                                 to += length;
 160                                 break;
 161
 162                         case '%':
 163                                 if (from[1] == '{') {
 164                                         *(to++) = *(from++);
 165
 166                                         length = rad_copy_variable(to, from);
 167                                         if (length < 0) {
 168                                                 radlog(L_ERR|L_CONS, "Invalid variable expansion passed as argument for external program");
 169                                                 return -1;
 170                                         }
 171                                         from += length;
 172                                         to += length;
 173                                 } else { /* FIXME: catch %%{ ? */
 174                                         *(to++) = *(from++);
 175                                 }
 176                                 break;
 177
 178                         default:
 179                                 *(to++) = *(from++);
 180                         }
 181                 } /* end of string, or found a space */
 182
 183                 *(to++) = '\0'; /* terminate the string */
 184         }
 185
 186         /*
 187          *      We have to have SOMETHING, at least.
 188          */
 189         if (argc <= 0) {
 190                 radlog(L_ERR, "Exec-Program: empty command line.");
 191                 return -1;
 192         }
 193
 194         /*
 195          *      Expand each string, as appropriate.
 196          */
 197         to = argv_buf;
 198         left = sizeof(argv_buf);
 199         for (i = 0; i < argc; i++) {
 200                 int sublen;
 201
 202                 /*
 203                  *      Don't touch argv's which won't be translated.
 204                  */
 205                 if (strchr(argv[i], '%') == NULL) continue;
 206
 207                 if (!request) continue;
 208
 209                 sublen = radius_xlat(to, left - 1, argv[i], request, NULL);
 210                 if (sublen <= 0) {
 211                         /*
 212                          *      Fail to be backwards compatible.
 213                          *
 214                          *      It's yucky, but it won't break anything,
 215                          *      and it won't cause security problems.
 216                          */
 217                         sublen = 0;
 218                 }
 219
 220                 argv[i] = to;
 221                 to += sublen;
 222                 *(to++) = '\0';
 223                 left -= sublen;
 224                 left--;
 225
 226                 if (left <= 0) {
 227                         radlog(L_ERR, "Exec-Program: Ran out of space while expanding arguments.");
 228                         return -1;
 229                 }
 230         }
 231         argv[argc] = NULL;
 232
 233 #ifndef __MINGW32__
 234         /*
 235          *      Open a pipe for child/parent communication, if necessary.
 236          */
 237         if (exec_wait) {
 238                 if (pipe(pd) != 0) {
 239                         radlog(L_ERR|L_CONS, "Couldn't open pipe: %s",
 240                                strerror(errno));
 241                         return -1;
 242                 }
 243         } else {
 244                 /*
 245                  *      We're not waiting, so we don't look for a
 246                  *      message, or VP's.
 247                  */
 248                 user_msg = NULL;
 249                 output_pairs = NULL;
 250         }
 251
 252         envp[0] = NULL;
 253
 254         if (input_pairs) {
 255                 int envlen;
 256                 char buffer[1024];
 257
 258                 /*
 259                  *      Set up the environment variables in the
 260                  *      parent, so we don't call libc functions that
 261                  *      hold mutexes.  They might be locked when we fork,
 262                  *      and will remain locked in the child.
 263                  */
 264                 envlen = 0;
 265
 266                 for (vp = input_pairs; vp != NULL; vp = vp->next) {
 267                         /*
 268                          *      Hmm... maybe we shouldn't pass the
 269                          *      user's password in an environment
 270                          *      variable...
 271                          */
 272                         snprintf(buffer, sizeof(buffer), "%s=", vp->name);
 273                         if (shell_escape) {
 274                                 for (p = buffer; *p != '='; p++) {
 275                                         if (*p == '-') {
 276                                                 *p = '_';
 277                                         } else if (isalpha((int) *p)) {
 278                                                 *p = toupper(*p);
 279                                         }
 280                                 }
 281                         }
 282
 283                         n = strlen(buffer);
 284                         vp_prints_value(buffer+n, sizeof(buffer) - n, vp, shell_escape);
 285
 286                         envp[envlen++] = strdup(buffer);
 287
 288                         /*
 289                          *      Don't add too many attributes.
 290                          */
 291                         if (envlen == (MAX_ENVP - 1)) break;
 292                 }
 293                 envp[envlen] = NULL;
 294         }
 295
 296         if (exec_wait) {
 297                 pid = rad_fork();       /* remember PID */
 298         } else {
 299                 pid = fork();           /* don't wait */
 300         }
 301
 302         if (pid == 0) {
 303                 int devnull;
 304
 305                 /*
 306                  *      Child process.
 307                  *
 308                  *      We try to be fail-safe here. So if ANYTHING
 309                  *      goes wrong, we exit with status 1.
 310                  */
 311
 312                 /*
 313                  *      Open STDIN to /dev/null
 314                  */
 315                 devnull = open("/dev/null", O_RDWR);
 316                 if (devnull < 0) {
 317                         radlog(L_ERR|L_CONS, "Failed opening /dev/null: %s\n",
 318                                strerror(errno));
 319                         exit(1);
 320                 }
 321                 dup2(devnull, STDIN_FILENO);
 322
 323                 /*
 324                  *      Only massage the pipe handles if the parent
 325                  *      has created them.
 326                  */
 327                 if (exec_wait) {
 328                         /*
 329                          *      pd[0] is the FD the child will read from,
 330                          *      which we don't want.
 331                          */
 332                         if (close(pd[0]) != 0) {
 333                                 radlog(L_ERR|L_CONS, "Can't close pipe: %s",
 334                                        strerror(errno));
 335                                 exit(1);
 336                         }
 337
 338                         /*
 339                          *      pd[1] is the FD that the child will write to,
 340                          *      so we make it STDOUT.
 341                          */
 342                         if (dup2(pd[1], STDOUT_FILENO) != 1) {
 343                                 radlog(L_ERR|L_CONS, "Can't dup stdout: %s",
 344                                        strerror(errno));
 345                                 exit(1);
 346                         }
 347
 348                 } else {        /* no pipe, STDOUT should be /dev/null */
 349                         dup2(devnull, STDOUT_FILENO);
 350                 }
 351
 352                 /*
 353                  *      If we're not debugging, then we can't do
 354                  *      anything with the error messages, so we throw
 355                  *      them away.
 356                  *
 357                  *      If we are debugging, then we want the error
 358                  *      messages to go to the STDERR of the server.
 359                  */
 360                 if (debug_flag == 0) {
 361                         dup2(devnull, STDERR_FILENO);
 362                 }
 363                 close(devnull);
 364
 365                 /*
 366                  *      The server may have MANY FD's open.  We don't
 367                  *      want to leave dangling FD's for the child process
 368                  *      to play funky games with, so we close them.
 369                  */
 370                 closefrom(3);
 371
 372                 execve(argv[0], argv, envp);
 373                 radlog(L_ERR, "Exec-Program: FAILED to execute %s: %s",
 374                        argv[0], strerror(errno));
 375                 exit(1);
 376         }
 377
 378         /*
 379          *      Free child environment variables
 380          */
 381         for (i = 0; envp[i] != NULL; i++) {
 382                 free(envp[i]);
 383         }
 384
 385         /*
 386          *      Parent process.
 387          */
 388         if (pid < 0) {
 389                 radlog(L_ERR|L_CONS, "Couldn't fork %s: %s",
 390                        argv[0], strerror(errno));
 391                 if (exec_wait) {
 392                         close(pd[0]);
 393                         close(pd[1]);
 394                 }
 395                 return -1;
 396         }
 397
 398         /*
 399          *      We're not waiting, exit, and ignore any child's status.
 400          */
 401         if (!exec_wait) {
 402                 return 0;
 403         }
 404
 405         /*
 406          *      Close the FD to which the child writes it's data.
 407          *
 408          *      If we can't close it, then we close pd[0], and return an
 409          *      error.
 410          */
 411         if (close(pd[1]) != 0) {
 412                 radlog(L_ERR|L_CONS, "Can't close pipe: %s", strerror(errno));
 413                 close(pd[0]);
 414                 return -1;
 415         }
 416
 417 #ifdef O_NONBLOCK
 418         /*
 419          *      Try to set it non-blocking.
 420          */
 421         do {
 422                 int flags;
 423
 424                 if ((flags = fcntl(pd[0], F_GETFL, NULL)) < 0)  {
 425                         nonblock = FALSE;
 426                         break;
 427                 }
 428
 429                 flags |= O_NONBLOCK;
 430                 if( fcntl(pd[0], F_SETFL, flags) < 0) {
 431                         nonblock = FALSE;
 432                         break;
 433                 }
 434         } while (0);
 435 #endif
 436
 437
 438         /*
 439          *      Read from the pipe until we doesn't get any more or
 440          *      until the message is full.
 441          */
 442         done = 0;
 443         left = sizeof(answer) - 1;
 444         gettimeofday(&start, NULL);
 445         while (1) {
 446                 int rcode;
 447                 fd_set fds;
 448                 struct timeval when, elapsed, wake;
 449
 450                 FD_ZERO(&fds);
 451                 FD_SET(pd[0], &fds);
 452
 453                 gettimeofday(&when, NULL);
 454                 tv_sub(&when, &start, &elapsed);
 455                 if (elapsed.tv_sec >= 10) goto too_long;
 456
 457                 when.tv_sec = 10;
 458                 when.tv_usec = 0;
 459                 tv_sub(&when, &elapsed, &wake);
 460
 461                 rcode = select(pd[0] + 1, &fds, NULL, NULL, &wake);
 462                 if (rcode == 0) {
 463                 too_long:
 464                         radlog(L_ERR, "Child PID %u is taking too much time: forcing failure and killing child.", pid);
 465                         kill(pid, SIGTERM);
 466                         close(pd[0]); /* should give SIGPIPE to child, too */
 467
 468                         /*
 469                          *      Clean up the child entry.
 470                          */
 471                         rad_waitpid(pid, &status);
 472                         return 1;
 473                 }
 474                 if (rcode < 0) {
 475                         if (errno == EINTR) continue;
 476                         break;
 477                 }
 478
 479 #ifdef O_NONBLOCK
 480                 /*
 481                  *      Read as many bytes as possible.  The kernel
 482                  *      will return the number of bytes available.
 483                  */
 484                 if (nonblock) {
 485                         status = read(pd[0], answer + done, left);
 486                 } else
 487 #endif
 488                         /*
 489                          *      There's at least 1 byte ready: read it.
 490                          */
 491                         status = read(pd[0], answer + done, 1);
 492
 493                 /*
 494                  *      Nothing more to read: stop.
 495                  */
 496                 if (status == 0) {
 497                         break;
 498                 }
 499
 500                 /*
 501                  *      Error: See if we have to continue.
 502                  */
 503                 if (status < 0) {
 504                         /*
 505                          *      We were interrupted: continue reading.
 506                          */
 507                         if (errno == EINTR) {
 508                                 continue;
 509                         }
 510
 511                         /*
 512                          *      There was another error.  Most likely
 513                          *      The child process has finished, and
 514                          *      exited.
 515                          */
 516                         break;
 517                 }
 518
 519                 done += status;
 520                 left -= status;
 521                 if (left <= 0) break;
 522         }
 523         answer[done] = 0;
 524
 525         /*
 526          *      Make sure that the writer can't block while writing to
 527          *      a pipe that no one is reading from anymore.
 528          */
 529         close(pd[0]);
 530
 531         DEBUG2("Exec-Program output: %s", answer);
 532
 533         /*
 534          *      Parse the output, if any.
 535          */
 536         if (done) {
 537                 n = T_OP_INVALID;
 538                 if (output_pairs) {
 539                         /*
 540                          *      For backwards compatibility, first check
 541                          *      for plain text (user_msg).
 542                          */
 543                         vp = NULL;
 544                         n = userparse(answer, &vp);
 545                         if (vp) {
 546                                 pairfree(&vp);
 547                         }
 548                 }
 549
 550                 if (n == T_OP_INVALID) {
 551                         DEBUG("Exec-Program-Wait: plaintext: %s", answer);
 552                         if (user_msg) {
 553                                 strlcpy(user_msg, answer, msg_len);
 554                         }
 555                 } else {
 556                         /*
 557                          *      HACK: Replace '\n' with ',' so that
 558                          *      userparse() can parse the buffer in
 559                          *      one go (the proper way would be to
 560                          *      fix userparse(), but oh well).
 561                          */
 562                         for (p = answer; *p; p++) {
 563                                 if (*p == '\n') {
 564                                         *p = comma ? ' ' : ',';
 565                                         p++;
 566                                         comma = 0;
 567                                 }
 568                                 if (*p == ',') comma++;
 569                         }
 570
 571                         /*
 572                          *      Replace any trailing comma by a NUL.
 573                          */
 574                         if (answer[strlen(answer) - 1] == ',') {
 575                                 answer[strlen(answer) - 1] = '\0';
 576                         }
 577
 578                         radlog(L_DBG,"Exec-Program-Wait: value-pairs: %s", answer);
 579                         if (userparse(answer, &vp) == T_OP_INVALID) {
 580                                 radlog(L_ERR, "Exec-Program-Wait: %s: unparsable reply", cmd);
 581
 582                         } else {
 583                                 /*
 584                                  *      Tell the caller about the value
 585                                  *      pairs.
 586                                  */
 587                                 *output_pairs = vp;
 588                         }
 589                 } /* else the answer was a set of VP's, not a text message */
 590         } /* else we didn't read anything from the child */
 591
 592         /*
 593          *      Call rad_waitpid (should map to waitpid on non-threaded
 594          *      or single-server systems).
 595          */
 596         child_pid = rad_waitpid(pid, &status);
 597         if (child_pid == 0) {
 598                 radlog(L_DBG, "Exec-Program: Timeout waiting for child");
 599                 return 2;
 600         }
 601
 602         if (child_pid == pid) {
 603                 if (WIFEXITED(status)) {
 604                         status = WEXITSTATUS(status);
 605                         radlog(L_DBG, "Exec-Program: returned: %d", status);
 606                         return status;
 607                 }
 608         }
 609
 610         radlog(L_ERR|L_CONS, "Exec-Program: Abnormal child exit: %s",
 611                strerror(errno));
 612         return 1;
 613 #else
 614         msg_len = msg_len;      /* -Wunused */
 615
 616         if (exec_wait) {
 617                 radlog(L_ERR, "Exec-Program-Wait is not supported");
 618                 return -1;
 619         }
 620
 621         /*
 622          *      We're not waiting, so we don't look for a
 623          *      message, or VP's.
 624          */
 625         user_msg = NULL;
 626         output_pairs = NULL;
 627
 628         {
 629                 /*
 630                  *      The _spawn and _exec families of functions are
 631                  *      found in Windows compiler libraries for
 632                  *      portability from UNIX. There is a variety of
 633                  *      functions, including the ability to pass
 634                  *      either a list or array of parameters, to
 635                  *      search in the PATH or otherwise, and whether
 636                  *      or not to pass an environment (a set of
 637                  *      environment variables). Using _spawn, you can
 638                  *      also specify whether you want the new process
 639                  *      to close your program (_P_OVERLAY), to wait
 640                  *      until the new process is finished (_P_WAIT) or
 641                  *      for the two to run concurrently (_P_NOWAIT).
 642
 643                  *      _spawn and _exec are useful for instances in
 644                  *      which you have simple requirements for running
 645                  *      the program, don't want the overhead of the
 646                  *      Windows header file, or are interested
 647                  *      primarily in portability.
 648                  */
 649
 650                 /*
 651                  *      FIXME: check return code... what is it?
 652                  */
 653                 _spawnve(_P_NOWAIT, argv[0], argv, envp);
 654         }
 655
 656         return 0;
 657 #endif
 658 }