lib/libpam/modules/pam_exec/pam_exec.c

   1 /*-
   2  * SPDX-License-Identifier: BSD-3-Clause
   3  *
   4  * Copyright (c) 2001,2003 Networks Associates Technology, Inc.
   5  * All rights reserved.
   6  *
   7  * This software was developed for the FreeBSD Project by ThinkSec AS and
   8  * NAI Labs, the Security Research Division of Network Associates, Inc.
   9  * under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the
  10  * DARPA CHATS research program.
  11  *
  12  * Redistribution and use in source and binary forms, with or without
  13  * modification, are permitted provided that the following conditions
  14  * are met:
  15  * 1. Redistributions of source code must retain the above copyright
  16  *    notice, this list of conditions and the following disclaimer.
  17  * 2. Redistributions in binary form must reproduce the above copyright
  18  *    notice, this list of conditions and the following disclaimer in the
  19  *    documentation and/or other materials provided with the distribution.
  20  * 3. The name of the author may not be used to endorse or promote
  21  *    products derived from this software without specific prior written
  22  *    permission.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  34  * SUCH DAMAGE.
  35  *
  36  * $FreeBSD: head/lib/libpam/modules/pam_exec/pam_exec.c 315164 2017-03-12 17:41:51Z pfg $
  37  */
  38
  39 #include <sys/types.h>
  40 #include <sys/wait.h>
  41
  42 #include <errno.h>
  43 #include <stdio.h>
  44 #include <stdlib.h>
  45 #include <string.h>
  46 #include <unistd.h>
  47
  48 #include <security/pam_appl.h>
  49 #include <security/pam_modules.h>
  50 #include <security/openpam.h>
  51
  52 #define ENV_ITEM(n) { (n), #n }
  53 static struct {
  54         int item;
  55         const char *name;
  56 } env_items[] = {
  57         ENV_ITEM(PAM_SERVICE),
  58         ENV_ITEM(PAM_USER),
  59         ENV_ITEM(PAM_TTY),
  60         ENV_ITEM(PAM_RHOST),
  61         ENV_ITEM(PAM_RUSER),
  62 };
  63
  64 struct pe_opts {
  65         int     return_prog_exit_status;
  66 };
  67
  68 #define PAM_RV_COUNT 24
  69
  70 static int
  71 parse_options(const char *func, int *argc, const char **argv[],
  72     struct pe_opts *options)
  73 {
  74         int i;
  75
  76         /*
  77          * Parse options:
  78          *   return_prog_exit_status:
  79          *     use the program exit status as the return code of pam_exec
  80          *   --:
  81          *     stop options parsing; what follows is the command to execute
  82          */
  83         options->return_prog_exit_status = 0;
  84
  85         for (i = 0; i < *argc; ++i) {
  86                 if (strcmp((*argv)[i], "return_prog_exit_status") == 0) {
  87                         openpam_log(PAM_LOG_DEBUG,
  88                             "%s: Option \"return_prog_exit_status\" enabled",
  89                             func);
  90                         options->return_prog_exit_status = 1;
  91                 } else {
  92                         if (strcmp((*argv)[i], "--") == 0) {
  93                                 (*argc)--;
  94                                 (*argv)++;
  95                         }
  96
  97                         break;
  98                 }
  99         }
 100
 101         (*argc) -= i;
 102         (*argv) += i;
 103
 104         return (0);
 105 }
 106
 107 static int
 108 _pam_exec(pam_handle_t *pamh __unused,
 109     const char *func, int flags __unused, int argc, const char *argv[],
 110     struct pe_opts *options)
 111 {
 112         int envlen, i, nitems, pam_err, status;
 113         int nitems_rv;
 114         char **envlist, **tmp, *envstr;
 115         volatile int childerr;
 116         pid_t pid;
 117
 118         /*
 119          * XXX For additional credit, divert child's stdin/stdout/stderr
 120          * to the conversation function.
 121          */
 122
 123         /* Check there's a program name left after parsing options. */
 124         if (argc < 1) {
 125                 openpam_log(PAM_LOG_ERROR, "%s: No program specified: aborting",
 126                     func);
 127                 return (PAM_SERVICE_ERR);
 128         }
 129
 130         /*
 131          * Set up the child's environment list. It consists of the PAM
 132          * environment, plus a few hand-picked PAM items, the pam_sm_*
 133          * function name calling it and, if return_prog_exit_status is
 134          * set, the valid return codes numerical values.
 135          */
 136         envlist = pam_getenvlist(pamh);
 137         for (envlen = 0; envlist[envlen] != NULL; ++envlen)
 138                 /* nothing */ ;
 139         nitems = sizeof(env_items) / sizeof(*env_items);
 140         /* Count PAM return values put in the environment. */
 141         nitems_rv = options->return_prog_exit_status ? PAM_RV_COUNT : 0;
 142         tmp = realloc(envlist, (envlen + nitems + 1 + nitems_rv + 1) *
 143             sizeof(*envlist));
 144         if (tmp == NULL) {
 145                 openpam_free_envlist(envlist);
 146                 return (PAM_BUF_ERR);
 147         }
 148         envlist = tmp;
 149         for (i = 0; i < nitems; ++i) {
 150                 const void *item;
 151
 152                 pam_err = pam_get_item(pamh, env_items[i].item, &item);
 153                 if (pam_err != PAM_SUCCESS || item == NULL)
 154                         continue;
 155                 asprintf(&envstr, "%s=%s", env_items[i].name,
 156                     (const char *)item);
 157                 if (envstr == NULL) {
 158                         openpam_free_envlist(envlist);
 159                         return (PAM_BUF_ERR);
 160                 }
 161                 envlist[envlen++] = envstr;
 162                 envlist[envlen] = NULL;
 163         }
 164
 165         /* Add the pam_sm_* function name to the environment. */
 166         asprintf(&envstr, "PAM_SM_FUNC=%s", func);
 167         if (envstr == NULL) {
 168                 openpam_free_envlist(envlist);
 169                 return (PAM_BUF_ERR);
 170         }
 171         envlist[envlen++] = envstr;
 172
 173         /* Add the PAM return values to the environment. */
 174         if (options->return_prog_exit_status) {
 175 #define ADD_PAM_RV_TO_ENV(name)                                         \
 176                 asprintf(&envstr, #name "=%d", name);                   \
 177                 if (envstr == NULL) {                                   \
 178                         openpam_free_envlist(envlist);                  \
 179                         return (PAM_BUF_ERR);                           \
 180                 }                                                       \
 181                 envlist[envlen++] = envstr
 182                 /*
 183                  * CAUTION: When adding/removing an item in the list
 184                  * below, be sure to update the value of PAM_RV_COUNT.
 185                  */
 186                 ADD_PAM_RV_TO_ENV(PAM_ABORT);
 187                 ADD_PAM_RV_TO_ENV(PAM_ACCT_EXPIRED);
 188                 ADD_PAM_RV_TO_ENV(PAM_AUTHINFO_UNAVAIL);
 189                 ADD_PAM_RV_TO_ENV(PAM_AUTHTOK_DISABLE_AGING);
 190                 ADD_PAM_RV_TO_ENV(PAM_AUTHTOK_ERR);
 191                 ADD_PAM_RV_TO_ENV(PAM_AUTHTOK_LOCK_BUSY);
 192                 ADD_PAM_RV_TO_ENV(PAM_AUTHTOK_RECOVERY_ERR);
 193                 ADD_PAM_RV_TO_ENV(PAM_AUTH_ERR);
 194                 ADD_PAM_RV_TO_ENV(PAM_BUF_ERR);
 195                 ADD_PAM_RV_TO_ENV(PAM_CONV_ERR);
 196                 ADD_PAM_RV_TO_ENV(PAM_CRED_ERR);
 197                 ADD_PAM_RV_TO_ENV(PAM_CRED_EXPIRED);
 198                 ADD_PAM_RV_TO_ENV(PAM_CRED_INSUFFICIENT);
 199                 ADD_PAM_RV_TO_ENV(PAM_CRED_UNAVAIL);
 200                 ADD_PAM_RV_TO_ENV(PAM_IGNORE);
 201                 ADD_PAM_RV_TO_ENV(PAM_MAXTRIES);
 202                 ADD_PAM_RV_TO_ENV(PAM_NEW_AUTHTOK_REQD);
 203                 ADD_PAM_RV_TO_ENV(PAM_PERM_DENIED);
 204                 ADD_PAM_RV_TO_ENV(PAM_SERVICE_ERR);
 205                 ADD_PAM_RV_TO_ENV(PAM_SESSION_ERR);
 206                 ADD_PAM_RV_TO_ENV(PAM_SUCCESS);
 207                 ADD_PAM_RV_TO_ENV(PAM_SYSTEM_ERR);
 208                 ADD_PAM_RV_TO_ENV(PAM_TRY_AGAIN);
 209                 ADD_PAM_RV_TO_ENV(PAM_USER_UNKNOWN);
 210         }
 211
 212         envlist[envlen] = NULL;
 213
 214         /*
 215          * Fork and run the command.  By using vfork() instead of fork(),
 216          * we can distinguish between an execve() failure and a non-zero
 217          * exit status from the command.
 218          */
 219         childerr = 0;
 220         if ((pid = vfork()) == 0) {
 221                 execve(argv[0], (char * const *)argv, (char * const *)envlist);
 222                 childerr = errno;
 223                 _exit(1);
 224         }
 225         openpam_free_envlist(envlist);
 226         if (pid == -1) {
 227                 openpam_log(PAM_LOG_ERROR, "%s: vfork(): %m", func);
 228                 return (PAM_SYSTEM_ERR);
 229         }
 230         while (waitpid(pid, &status, 0) == -1) {
 231                 if (errno == EINTR)
 232                         continue;
 233                 openpam_log(PAM_LOG_ERROR, "%s: waitpid(): %m", func);
 234                 return (PAM_SYSTEM_ERR);
 235         }
 236         if (childerr != 0) {
 237                 openpam_log(PAM_LOG_ERROR, "%s: execve(): %m", func);
 238                 return (PAM_SYSTEM_ERR);
 239         }
 240         if (WIFSIGNALED(status)) {
 241                 openpam_log(PAM_LOG_ERROR, "%s: %s caught signal %d%s",
 242                     func, argv[0], WTERMSIG(status),
 243                     WCOREDUMP(status) ? " (core dumped)" : "");
 244                 return (PAM_SERVICE_ERR);
 245         }
 246         if (!WIFEXITED(status)) {
 247                 openpam_log(PAM_LOG_ERROR, "%s: unknown status 0x%x",
 248                     func, status);
 249                 return (PAM_SERVICE_ERR);
 250         }
 251
 252         if (options->return_prog_exit_status) {
 253                 openpam_log(PAM_LOG_DEBUG,
 254                     "%s: Use program exit status as return value: %d",
 255                     func, WEXITSTATUS(status));
 256                 return (WEXITSTATUS(status));
 257         } else {
 258                 return (WEXITSTATUS(status) == 0 ?
 259                     PAM_SUCCESS : PAM_PERM_DENIED);
 260         }
 261 }
 262
 263 PAM_EXTERN int
 264 pam_sm_authenticate(pam_handle_t *pamh, int flags,
 265     int argc, const char *argv[])
 266 {
 267         int ret;
 268         struct pe_opts options;
 269
 270         ret = parse_options(__func__, &argc, &argv, &options);
 271         if (ret != 0)
 272                 return (PAM_SERVICE_ERR);
 273
 274         ret = _pam_exec(pamh, __func__, flags, argc, argv, &options);
 275
 276         /*
 277          * We must check that the program returned a valid code for this
 278          * function.
 279          */
 280         switch (ret) {
 281         case PAM_SUCCESS:
 282         case PAM_ABORT:
 283         case PAM_AUTHINFO_UNAVAIL:
 284         case PAM_AUTH_ERR:
 285         case PAM_BUF_ERR:
 286         case PAM_CONV_ERR:
 287         case PAM_CRED_INSUFFICIENT:
 288         case PAM_IGNORE:
 289         case PAM_MAXTRIES:
 290         case PAM_PERM_DENIED:
 291         case PAM_SERVICE_ERR:
 292         case PAM_SYSTEM_ERR:
 293         case PAM_USER_UNKNOWN:
 294                 break;
 295         default:
 296                 openpam_log(PAM_LOG_ERROR, "%s returned invalid code %d",
 297                     argv[0], ret);
 298                 ret = PAM_SERVICE_ERR;
 299         }
 300
 301         return (ret);
 302 }
 303
 304 PAM_EXTERN int
 305 pam_sm_setcred(pam_handle_t *pamh, int flags,
 306     int argc, const char *argv[])
 307 {
 308         int ret;
 309         struct pe_opts options;
 310
 311         ret = parse_options(__func__, &argc, &argv, &options);
 312         if (ret != 0)
 313                 return (PAM_SERVICE_ERR);
 314
 315         ret = _pam_exec(pamh, __func__, flags, argc, argv, &options);
 316
 317         /*
 318          * We must check that the program returned a valid code for this
 319          * function.
 320          */
 321         switch (ret) {
 322         case PAM_SUCCESS:
 323         case PAM_ABORT:
 324         case PAM_BUF_ERR:
 325         case PAM_CONV_ERR:
 326         case PAM_CRED_ERR:
 327         case PAM_CRED_EXPIRED:
 328         case PAM_CRED_UNAVAIL:
 329         case PAM_IGNORE:
 330         case PAM_PERM_DENIED:
 331         case PAM_SERVICE_ERR:
 332         case PAM_SYSTEM_ERR:
 333         case PAM_USER_UNKNOWN:
 334                 break;
 335         default:
 336                 openpam_log(PAM_LOG_ERROR, "%s returned invalid code %d",
 337                     argv[0], ret);
 338                 ret = PAM_SERVICE_ERR;
 339         }
 340
 341         return (ret);
 342 }
 343
 344 PAM_EXTERN int
 345 pam_sm_acct_mgmt(pam_handle_t *pamh, int flags,
 346     int argc, const char *argv[])
 347 {
 348         int ret;
 349         struct pe_opts options;
 350
 351         ret = parse_options(__func__, &argc, &argv, &options);
 352         if (ret != 0)
 353                 return (PAM_SERVICE_ERR);
 354
 355         ret = _pam_exec(pamh, __func__, flags, argc, argv, &options);
 356
 357         /*
 358          * We must check that the program returned a valid code for this
 359          * function.
 360          */
 361         switch (ret) {
 362         case PAM_SUCCESS:
 363         case PAM_ABORT:
 364         case PAM_ACCT_EXPIRED:
 365         case PAM_AUTH_ERR:
 366         case PAM_BUF_ERR:
 367         case PAM_CONV_ERR:
 368         case PAM_IGNORE:
 369         case PAM_NEW_AUTHTOK_REQD:
 370         case PAM_PERM_DENIED:
 371         case PAM_SERVICE_ERR:
 372         case PAM_SYSTEM_ERR:
 373         case PAM_USER_UNKNOWN:
 374                 break;
 375         default:
 376                 openpam_log(PAM_LOG_ERROR, "%s returned invalid code %d",
 377                     argv[0], ret);
 378                 ret = PAM_SERVICE_ERR;
 379         }
 380
 381         return (ret);
 382 }
 383
 384 PAM_EXTERN int
 385 pam_sm_open_session(pam_handle_t *pamh, int flags,
 386     int argc, const char *argv[])
 387 {
 388         int ret;
 389         struct pe_opts options;
 390
 391         ret = parse_options(__func__, &argc, &argv, &options);
 392         if (ret != 0)
 393                 return (PAM_SERVICE_ERR);
 394
 395         ret = _pam_exec(pamh, __func__, flags, argc, argv, &options);
 396
 397         /*
 398          * We must check that the program returned a valid code for this
 399          * function.
 400          */
 401         switch (ret) {
 402         case PAM_SUCCESS:
 403         case PAM_ABORT:
 404         case PAM_BUF_ERR:
 405         case PAM_CONV_ERR:
 406         case PAM_IGNORE:
 407         case PAM_PERM_DENIED:
 408         case PAM_SERVICE_ERR:
 409         case PAM_SESSION_ERR:
 410         case PAM_SYSTEM_ERR:
 411                 break;
 412         default:
 413                 openpam_log(PAM_LOG_ERROR, "%s returned invalid code %d",
 414                     argv[0], ret);
 415                 ret = PAM_SERVICE_ERR;
 416         }
 417
 418         return (ret);
 419 }
 420
 421 PAM_EXTERN int
 422 pam_sm_close_session(pam_handle_t *pamh, int flags,
 423     int argc, const char *argv[])
 424 {
 425         int ret;
 426         struct pe_opts options;
 427
 428         ret = parse_options(__func__, &argc, &argv, &options);
 429         if (ret != 0)
 430                 return (PAM_SERVICE_ERR);
 431
 432         ret = _pam_exec(pamh, __func__, flags, argc, argv, &options);
 433
 434         /*
 435          * We must check that the program returned a valid code for this
 436          * function.
 437          */
 438         switch (ret) {
 439         case PAM_SUCCESS:
 440         case PAM_ABORT:
 441         case PAM_BUF_ERR:
 442         case PAM_CONV_ERR:
 443         case PAM_IGNORE:
 444         case PAM_PERM_DENIED:
 445         case PAM_SERVICE_ERR:
 446         case PAM_SESSION_ERR:
 447         case PAM_SYSTEM_ERR:
 448                 break;
 449         default:
 450                 openpam_log(PAM_LOG_ERROR, "%s returned invalid code %d",
 451                     argv[0], ret);
 452                 ret = PAM_SERVICE_ERR;
 453         }
 454
 455         return (ret);
 456 }
 457
 458 PAM_EXTERN int
 459 pam_sm_chauthtok(pam_handle_t *pamh, int flags,
 460     int argc, const char *argv[])
 461 {
 462         int ret;
 463         struct pe_opts options;
 464
 465         ret = parse_options(__func__, &argc, &argv, &options);
 466         if (ret != 0)
 467                 return (PAM_SERVICE_ERR);
 468
 469         ret = _pam_exec(pamh, __func__, flags, argc, argv, &options);
 470
 471         /*
 472          * We must check that the program returned a valid code for this
 473          * function.
 474          */
 475         switch (ret) {
 476         case PAM_SUCCESS:
 477         case PAM_ABORT:
 478         case PAM_AUTHTOK_DISABLE_AGING:
 479         case PAM_AUTHTOK_ERR:
 480         case PAM_AUTHTOK_LOCK_BUSY:
 481         case PAM_AUTHTOK_RECOVERY_ERR:
 482         case PAM_BUF_ERR:
 483         case PAM_CONV_ERR:
 484         case PAM_IGNORE:
 485         case PAM_PERM_DENIED:
 486         case PAM_SERVICE_ERR:
 487         case PAM_SYSTEM_ERR:
 488         case PAM_TRY_AGAIN:
 489                 break;
 490         default:
 491                 openpam_log(PAM_LOG_ERROR, "%s returned invalid code %d",
 492                     argv[0], ret);
 493                 ret = PAM_SERVICE_ERR;
 494         }
 495
 496         return (ret);
 497 }
 498
 499 PAM_MODULE_ENTRY("pam_exec");