lib/libpam/modules/pam_chroot/pam_chroot.c

   1 /*      $NetBSD: pam_chroot.c,v 1.3 2005/03/31 15:11:54 thorpej Exp $   */
   2
   3 /*-
   4  * Copyright (c) 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
  37 #include <sys/cdefs.h>
  38 #ifdef __FreeBSD__
  39 __FBSDID("$FreeBSD: src/lib/libpam/modules/pam_chroot/pam_chroot.c,v 1.3 2003/04/30 00:40:24 des Exp $");
  40 #else
  41 __RCSID("$NetBSD: pam_chroot.c,v 1.3 2005/03/31 15:11:54 thorpej Exp $");
  42 #endif
  43
  44 #include <sys/param.h>
  45
  46 #include <pwd.h>
  47 #include <stdio.h>
  48 #include <string.h>
  49 #include <unistd.h>
  50
  51 #define PAM_SM_SESSION
  52
  53 #include <security/pam_appl.h>
  54 #include <security/pam_modules.h>
  55 #include <security/openpam.h>
  56
  57 PAM_EXTERN int
  58 pam_sm_open_session(pam_handle_t *pamh, int flags __unused,
  59     int argc __unused, const char *argv[] __unused)
  60 {
  61         const char *dir, *end, *cwd, *user;
  62         struct passwd *pwd, pwres;
  63         char buf[PATH_MAX];
  64         char pwbuf[1024];
  65
  66         if (pam_get_user(pamh, &user, NULL) != PAM_SUCCESS ||
  67             user == NULL ||
  68             getpwnam_r(user, &pwres, pwbuf, sizeof(pwbuf), &pwd) != 0 ||
  69             pwd == NULL)
  70                 return (PAM_SESSION_ERR);
  71         if (pwd->pw_uid == 0 && !openpam_get_option(pamh, "also_root"))
  72                 return (PAM_SUCCESS);
  73         if (pwd->pw_dir == NULL)
  74                 return (PAM_SESSION_ERR);
  75         if ((end = strstr(pwd->pw_dir, "/./")) != NULL) {
  76                 if (snprintf(buf, sizeof(buf), "%.*s",
  77                     (int)(end - pwd->pw_dir), pwd->pw_dir) > (int)sizeof(buf)) {
  78                         openpam_log(PAM_LOG_ERROR,
  79                             "%s's home directory is too long", user);
  80                         return (PAM_SESSION_ERR);
  81                 }
  82                 dir = buf;
  83                 cwd = end + 2;
  84         } else if ((dir = openpam_get_option(pamh, "dir")) != NULL) {
  85                 if ((cwd = openpam_get_option(pamh, "cwd")) == NULL)
  86                         cwd = "/";
  87         } else {
  88                 if (openpam_get_option(pamh, "always")) {
  89                         openpam_log(PAM_LOG_ERROR,
  90                             "%s has no chroot directory", user);
  91                         return (PAM_SESSION_ERR);
  92                 }
  93                 return (PAM_SUCCESS);
  94         }
  95
  96         openpam_log(PAM_LOG_DEBUG, "chrooting %s to %s", dir, user);
  97
  98         if (chroot(dir) == -1) {
  99                 openpam_log(PAM_LOG_ERROR, "chroot(): %m");
 100                 return (PAM_SESSION_ERR);
 101         }
 102         if (chdir(cwd) == -1) {
 103                 openpam_log(PAM_LOG_ERROR, "chdir(): %m");
 104                 return (PAM_SESSION_ERR);
 105         }
 106         pam_setenv(pamh, "HOME", cwd, 1);
 107         return (PAM_SUCCESS);
 108 }
 109
 110 PAM_EXTERN int
 111 pam_sm_close_session(pam_handle_t *pamh __unused, int flags __unused,
 112     int argc __unused, const char *argv[] __unused)
 113 {
 114
 115         return (PAM_SUCCESS);
 116 }
 117
 118 PAM_MODULE_ENTRY("pam_chroot");