lib/pam_module/pam_chroot/pam_chroot.c

   1 /*-
   2  * Copyright (c) 2003 Networks Associates Technology, Inc.
   3  * All rights reserved.
   4  *
   5  * This software was developed for the FreeBSD Project by ThinkSec AS and
   6  * NAI Labs, the Security Research Division of Network Associates, Inc.
   7  * under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the
   8  * DARPA CHATS research program.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  * 3. The name of the author may not be used to endorse or promote
  19  *    products derived from this software without specific prior written
  20  *    permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  *
  34  * $FreeBSD: src/lib/libpam/modules/pam_chroot/pam_chroot.c,v 1.3 2003/04/30 00:40:24 des Exp $
  35  */
  36
  37 #include <sys/param.h>
  38
  39 #include <pwd.h>
  40 #include <stdio.h>
  41 #include <string.h>
  42 #include <unistd.h>
  43
  44 #define PAM_SM_SESSION
  45
  46 #include <security/pam_appl.h>
  47 #include <security/pam_modules.h>
  48 #include <security/openpam.h>
  49
  50 PAM_EXTERN int
  51 pam_sm_open_session(pam_handle_t *pamh, int flags __unused,
  52                     int argc __unused, const char *argv[] __unused)
  53 {
  54         const char *dir, *end, *cwd, *user;
  55         struct passwd *pwd;
  56         char buf[PATH_MAX];
  57
  58         if (pam_get_user(pamh, &user, NULL) != PAM_SUCCESS ||
  59             user == NULL || (pwd = getpwnam(user)) == NULL)
  60                 return (PAM_SESSION_ERR);
  61         if (pwd->pw_uid == 0 && !openpam_get_option(pamh, "also_root"))
  62                 return (PAM_SUCCESS);
  63         if (pwd->pw_dir == NULL)
  64                 return (PAM_SESSION_ERR);
  65         if ((end = strstr(pwd->pw_dir, "/./")) != NULL) {
  66                 if (snprintf(buf, sizeof(buf), "%.*s",
  67                     (int)(end - pwd->pw_dir), pwd->pw_dir) > (int)sizeof(buf)) {
  68                         openpam_log(PAM_LOG_ERROR,
  69                             "%s's home directory is too long", user);
  70                         return (PAM_SESSION_ERR);
  71                 }
  72                 dir = buf;
  73                 cwd = end + 2;
  74         } else if ((dir = openpam_get_option(pamh, "dir")) != NULL) {
  75                 if ((cwd = openpam_get_option(pamh, "cwd")) == NULL)
  76                         cwd = "/";
  77         } else {
  78                 if (openpam_get_option(pamh, "always")) {
  79                         openpam_log(PAM_LOG_ERROR,
  80                             "%s has no chroot directory", user);
  81                         return (PAM_SESSION_ERR);
  82                 }
  83                 return (PAM_SUCCESS);
  84         }
  85
  86         openpam_log(PAM_LOG_DEBUG, "chrooting %s to %s", dir, user);
  87
  88         if (chroot(dir) == -1) {
  89                 openpam_log(PAM_LOG_ERROR, "chroot(): %m");
  90                 return (PAM_SESSION_ERR);
  91         }
  92         if (chdir(cwd) == -1) {
  93                 openpam_log(PAM_LOG_ERROR, "chdir(): %m");
  94                 return (PAM_SESSION_ERR);
  95         }
  96         pam_setenv(pamh, "HOME", cwd, 1);
  97         return (PAM_SUCCESS);
  98 }
  99
 100 PAM_EXTERN int
 101 pam_sm_close_session(pam_handle_t *pamh __unused, int flags __unused,
 102                      int argc __unused, const char *argv[] __unused)
 103 {
 104
 105         return (PAM_SUCCESS);
 106 }
 107
 108 PAM_MODULE_ENTRY("pam_chroot");