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  *      Execute a program on successful authentication.
  48  *      Return 0 if exec_wait == 0.
  49  *      Return the exit code of the called program if exec_wait != 0.
  50  *      Return -1 on fork/other errors in the parent process.
  51  */
  52 int radius_exec_program(const char *cmd, REQUEST *request,
  53                         int exec_wait,
  54                         char *user_msg, int msg_len,
  55                         VALUE_PAIR *input_pairs,
  56                         VALUE_PAIR **output_pairs,
  57                         int shell_escape)
  58 {
  59         VALUE_PAIR *vp;
  60         char mycmd[1024];
  61         char answer[4096];
  62         char argv_buf[4096];
  63         char *argv[MAX_ARGV];
  64         const char *from;
  65         char *p, *to;
  66         int pd[2];
  67         pid_t pid, child_pid;
  68         int argc = -1;
  69         int comma = 0;
  70         int status;
  71         int i;
  72         int n, left, done;
  73
  74         if (user_msg) *user_msg = '\0';
  75         if (output_pairs) *output_pairs = NULL;
  76
  77         if (strlen(cmd) > (sizeof(mycmd) - 1)) {
  78                 radlog(L_ERR|L_CONS, "Command line is too long");
  79                 return -1;
  80         }
  81
  82         /*
  83          *      Check for bad escapes.
  84          */
  85         if (cmd[strlen(cmd) - 1] == '\\') {
  86                 radlog(L_ERR|L_CONS, "Command line has final backslash, without a following character");
  87                 return -1;
  88         }
  89
  90         strlcpy(mycmd, cmd, sizeof(mycmd));
  91
  92         /*
  93          *      Split the string into argv's BEFORE doing radius_xlat...
  94          */
  95         from = cmd;
  96         to = mycmd;
  97         argc = 0;
  98         while (*from) {
  99                 int length;
 100
 101                 /*
 102                  *      Skip spaces.
 103                  */
 104                 if ((*from == ' ') || (*from == '\t')) {
 105                         from++;
 106                         continue;
 107                 }
 108
 109                 argv[argc] = to;
 110                 argc++;
 111
 112                 if (argc >= (MAX_ARGV - 1)) break;
 113
 114                 /*
 115                  *      Copy the argv over to our buffer.
 116                  */
 117                 while (*from && (*from != ' ') && (*from != '\t')) {
 118                         if (to >= mycmd + sizeof(mycmd) - 1) {
 119                                 return -1; /* ran out of space */
 120                         }
 121
 122                         switch (*from) {
 123                         case '"':
 124                         case '\'':
 125                                 length = rad_copy_string(to, from);
 126                                 if (length < 0) {
 127                                         radlog(L_ERR|L_CONS, "Invalid string passed as argument for external program");
 128                                         return -1;
 129                                 }
 130                                 from += length;
 131                                 to += length;
 132                                 break;
 133
 134                         case '%':
 135                                 if (from[1] == '{') {
 136                                         *(to++) = *(from++);
 137
 138                                         length = rad_copy_variable(to, from);
 139                                         if (length < 0) {
 140                                                 radlog(L_ERR|L_CONS, "Invalid variable expansion passed as argument for external program");
 141                                                 return -1;
 142                                         }
 143                                         from += length;
 144                                         to += length;
 145                                 } else { /* FIXME: catch %%{ ? */
 146                                         *(to++) = *(from++);
 147                                 }
 148                                 break;
 149
 150                         default:
 151                                 *(to++) = *(from++);
 152                         }
 153                 } /* end of string, or found a space */
 154
 155                 *(to++) = '\0'; /* terminate the string */
 156         }
 157
 158         /*
 159          *      We have to have SOMETHING, at least.
 160          */
 161         if (argc <= 0) {
 162                 radlog(L_ERR, "Exec-Program: empty command line.");
 163                 return -1;
 164         }
 165
 166         /*
 167          *      Expand each string, as appropriate.
 168          */
 169         to = argv_buf;
 170         left = sizeof(argv_buf);
 171         for (i = 0; i < argc; i++) {
 172                 int sublen;
 173
 174                 /*
 175                  *      Don't touch argv's which won't be translated.
 176                  */
 177                 if (strchr(argv[i], '%') == NULL) continue;
 178
 179                 sublen = radius_xlat(to, left - 1, argv[i], request, NULL);
 180                 if (sublen <= 0) {
 181                         /*
 182                          *      Fail to be backwards compatible.
 183                          *
 184                          *      It's yucky, but it won't break anything,
 185                          *      and it won't cause security problems.
 186                          */
 187                         sublen = 0;
 188                 }
 189
 190                 argv[i] = to;
 191                 to += sublen;
 192                 *(to++) = '\0';
 193                 left -= sublen;
 194                 left--;
 195
 196                 if (left <= 0) {
 197                         radlog(L_ERR, "Exec-Program: Ran out of space while expanding arguments.");
 198                         return -1;
 199                 }
 200         }
 201         argv[argc] = NULL;
 202
 203         /*
 204          *      Open a pipe for child/parent communication, if necessary.
 205          */
 206         if (exec_wait) {
 207                 if (pipe(pd) != 0) {
 208                         radlog(L_ERR|L_CONS, "Couldn't open pipe: %s",
 209                                strerror(errno));
 210                         return -1;
 211                 }
 212         } else {
 213                 /*
 214                  *      We're not waiting, so we don't look for a
 215                  *      message, or VP's.
 216                  */
 217                 user_msg = NULL;
 218                 output_pairs = NULL;
 219         }
 220
 221         if (exec_wait) {
 222                 pid = rad_fork();       /* remember PID */
 223         } else {
 224                 pid = fork();           /* don't wait */
 225         }
 226
 227         if (pid == 0) {
 228 #define MAX_ENVP 1024
 229                 int devnull;
 230                 char *envp[MAX_ENVP];
 231                 int envlen;
 232                 char buffer[1024];
 233
 234                 /*
 235                  *      Child process.
 236                  *
 237                  *      We try to be fail-safe here. So if ANYTHING
 238                  *      goes wrong, we exit with status 1.
 239                  */
 240
 241                 /*
 242                  *      Open STDIN to /dev/null
 243                  */
 244                 devnull = open("/dev/null", O_RDWR);
 245                 if (devnull < 0) {
 246                         radlog(L_ERR|L_CONS, "Failed opening /dev/null: %s\n",
 247                                strerror(errno));
 248                         exit(1);
 249                 }
 250                 dup2(devnull, STDIN_FILENO);
 251
 252                 /*
 253                  *      Only massage the pipe handles if the parent
 254                  *      has created them.
 255                  */
 256                 if (exec_wait) {
 257                         /*
 258                          *      pd[0] is the FD the child will read from,
 259                          *      which we don't want.
 260                          */
 261                         if (close(pd[0]) != 0) {
 262                                 radlog(L_ERR|L_CONS, "Can't close pipe: %s",
 263                                        strerror(errno));
 264                                 exit(1);
 265                         }
 266
 267                         /*
 268                          *      pd[1] is the FD that the child will write to,
 269                          *      so we make it STDOUT.
 270                          */
 271                         if (dup2(pd[1], STDOUT_FILENO) != 1) {
 272                                 radlog(L_ERR|L_CONS, "Can't dup stdout: %s",
 273                                        strerror(errno));
 274                                 exit(1);
 275                         }
 276
 277                 } else {        /* no pipe, STDOUT should be /dev/null */
 278                         dup2(devnull, STDOUT_FILENO);
 279                 }
 280
 281                 /*
 282                  *      If we're not debugging, then we can't do
 283                  *      anything with the error messages, so we throw
 284                  *      them away.
 285                  *
 286                  *      If we are debugging, then we want the error
 287                  *      messages to go to the STDERR of the server.
 288                  */
 289                 if (debug_flag == 0) {
 290                         dup2(devnull, STDERR_FILENO);
 291                 }
 292                 close(devnull);
 293
 294                 /*
 295                  *      The server may have MANY FD's open.  We don't
 296                  *      want to leave dangling FD's for the child process
 297                  *      to play funky games with, so we close them.
 298                  */
 299                 closefrom(3);
 300
 301                 /*
 302                  *      Set up the environment variables.
 303                  *      We're in the child, and it will exit in 4 lines
 304                  *      anyhow, so memory allocation isn't an issue.
 305                  */
 306                 envlen = 0;
 307
 308                 for (vp = input_pairs; vp != NULL; vp = vp->next) {
 309                         /*
 310                          *      Hmm... maybe we shouldn't pass the
 311                          *      user's password in an environment
 312                          *      variable...
 313                          */
 314                         snprintf(buffer, sizeof(buffer), "%s=", vp->name);
 315                         if (shell_escape) {
 316                                 for (p = buffer; *p != '='; p++) {
 317                                         if (*p == '-') {
 318                                                 *p = '_';
 319                                         } else if (isalpha((int) *p)) {
 320                                                 *p = toupper(*p);
 321                                         }
 322                                 }
 323                         }
 324
 325                         n = strlen(buffer);
 326                         vp_prints_value(buffer+n, sizeof(buffer) - n, vp, shell_escape);
 327
 328                         envp[envlen++] = strdup(buffer);
 329
 330                         /*
 331                          *      Don't add too many attributes.
 332                          */
 333                         if (envlen == (MAX_ENVP - 1)) break;
 334                 }
 335                 envp[envlen] = NULL;
 336
 337                 execve(argv[0], argv, envp);
 338                 radlog(L_ERR, "Exec-Program: FAILED to execute %s: %s",
 339                        argv[0], strerror(errno));
 340                 exit(1);
 341         }
 342
 343         /*
 344          *      Parent process.
 345          */
 346         if (pid < 0) {
 347                 radlog(L_ERR|L_CONS, "Couldn't fork %s: %s",
 348                        argv[0], strerror(errno));
 349                 return -1;
 350         }
 351
 352         /*
 353          *      We're not waiting, exit, and ignore any child's status.
 354          */
 355         if (!exec_wait) {
 356                 return 0;
 357         }
 358
 359         /*
 360          *      Close the FD to which the child writes it's data.
 361          *
 362          *      If we can't close it, then we close pd[0], and return an
 363          *      error.
 364          */
 365         if (close(pd[1]) != 0) {
 366                 radlog(L_ERR|L_CONS, "Can't close pipe: %s", strerror(errno));
 367                 close(pd[0]);
 368                 return -1;
 369         }
 370
 371         /*
 372          *      Read from the pipe until we doesn't get any more or
 373          *      until the message is full.
 374          */
 375         done = 0;
 376         left = sizeof(answer) - 1;
 377         while (1) {
 378                 status = read(pd[0], answer + done, left);
 379                 /*
 380                  *      Nothing more to read: stop.
 381                  */
 382                 if (status == 0) {
 383                         break;
 384                 }
 385
 386                 /*
 387                  *      Error: See if we have to continue.
 388                  */
 389                 if (status < 0) {
 390                         /*
 391                          *      We were interrupted: continue reading.
 392                          */
 393                         if (errno == EINTR) {
 394                                 continue;
 395                         }
 396
 397                         /*
 398                          *      There was another error.  Most likely
 399                          *      The child process has finished, and
 400                          *      exited.
 401                          */
 402                         break;
 403                 }
 404
 405                 done += status;
 406                 left -= status;
 407                 if (left <= 0) break;
 408         }
 409         answer[done] = 0;
 410
 411         /*
 412          *      Make sure that the writer can't block while writing to
 413          *      a pipe that no one is reading from anymore.
 414          */
 415         close(pd[0]);
 416
 417         DEBUG2("Exec-Program output: %s", answer);
 418
 419         /*
 420          *      Parse the output, if any.
 421          */
 422         if (done) {
 423                 n = T_OP_INVALID;
 424                 if (output_pairs) {
 425                         /*
 426                          *      For backwards compatibility, first check
 427                          *      for plain text (user_msg).
 428                          */
 429                         vp = NULL;
 430                         n = userparse(answer, &vp);
 431                         if (vp) {
 432                                 pairfree(&vp);
 433                         }
 434                 }
 435
 436                 if (n == T_OP_INVALID) {
 437                         DEBUG("Exec-Program-Wait: plaintext: %s", answer);
 438                         if (user_msg) {
 439                                 strlcpy(user_msg, answer, msg_len);
 440                         }
 441                 } else {
 442                         /*
 443                          *      HACK: Replace '\n' with ',' so that
 444                          *      userparse() can parse the buffer in
 445                          *      one go (the proper way would be to
 446                          *      fix userparse(), but oh well).
 447                          */
 448                         for (p = answer; *p; p++) {
 449                                 if (*p == '\n') {
 450                                         *p = comma ? ' ' : ',';
 451                                         p++;
 452                                         comma = 0;
 453                                 }
 454                                 if (*p == ',') comma++;
 455                         }
 456
 457                         /*
 458                          *      Replace any trailing comma by a NUL.
 459                          */
 460                         if (answer[strlen(answer) - 1] == ',') {
 461                                 answer[strlen(answer) - 1] = '\0';
 462                         }
 463
 464                         radlog(L_DBG,"Exec-Program-Wait: value-pairs: %s", answer);
 465                         if (userparse(answer, &vp) == T_OP_INVALID) {
 466                                 radlog(L_ERR, "Exec-Program-Wait: %s: unparsable reply", cmd);
 467
 468                         } else {
 469                                 /*
 470                                  *      Tell the caller about the value
 471                                  *      pairs.
 472                                  */
 473                                 *output_pairs = vp;
 474                         }
 475                 } /* else the answer was a set of VP's, not a text message */
 476         } /* else we didn't read anything from the child */
 477
 478         /*
 479          *      Call rad_waitpid (should map to waitpid on non-threaded
 480          *      or single-server systems).
 481          */
 482         child_pid = rad_waitpid(pid, &status);
 483         if (child_pid == 0) {
 484                 radlog(L_DBG, "Exec-Program: Timeout waiting for child");
 485                 return 2;
 486         }
 487
 488         if (child_pid == pid) {
 489                 if (WIFEXITED(status)) {
 490                         status = WEXITSTATUS(status);
 491                         radlog(L_DBG, "Exec-Program: returned: %d", status);
 492                         return status;
 493                 }
 494         }
 495
 496         radlog(L_ERR|L_CONS, "Exec-Program: Abnormal child exit: %s",
 497                strerror(errno));
 498         return 1;
 499 }