lib/pam_module/pam_self/pam_self.c

   1 /*-
   2  * Copyright (c) 2001 Mark R V Murray
   3  * All rights reserved.
   4  * Copyright (c) 2001,2002 Networks Associates Technology, Inc.
   5  * All rights reserved.
   6  *
   7  * Portions of this software were developed for the FreeBSD Project by
   8  * ThinkSec AS and NAI Labs, the Security Research Division of Network
   9  * Associates, Inc.  under DARPA/SPAWAR contract N66001-01-C-8035
  10  * ("CBOSS"), as part of the 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: src/lib/libpam/modules/pam_self/pam_self.c,v 1.9 2002/04/12 22:27:24 des Exp $
  37  */
  38
  39 #define _BSD_SOURCE
  40
  41 #include <pwd.h>
  42 #include <unistd.h>
  43 #include <syslog.h>
  44
  45 #define PAM_SM_AUTH
  46
  47 #include <security/pam_appl.h>
  48 #include <security/pam_modules.h>
  49 #include <security/pam_mod_misc.h>
  50
  51 #define OPT_ALLOW_ROOT "allow_root"
  52
  53 PAM_EXTERN int
  54 pam_sm_authenticate(pam_handle_t *pamh, int flags __unused,
  55                     int argc __unused, const char *argv[] __unused)
  56 {
  57         struct passwd *pwd;
  58         const char *luser;
  59         int pam_err;
  60         uid_t uid;
  61
  62         pam_err = pam_get_user(pamh, &luser, NULL);
  63         if (pam_err != PAM_SUCCESS)
  64                 return (pam_err);
  65         if (luser == NULL || (pwd = getpwnam(luser)) == NULL)
  66                 return (PAM_AUTH_ERR);
  67
  68         uid = getuid();
  69         if (uid == 0 && !openpam_get_option(pamh, OPT_ALLOW_ROOT))
  70                 return (PAM_AUTH_ERR);
  71
  72         if (uid == (uid_t)pwd->pw_uid)
  73                 return (PAM_SUCCESS);
  74
  75         PAM_VERBOSE_ERROR("Refused; source and target users differ");
  76
  77         return (PAM_AUTH_ERR);
  78 }
  79
  80 PAM_EXTERN int
  81 pam_sm_setcred(pam_handle_t *pamh __unused, int flags __unused,
  82                int argc __unused, const char *argv[] __unused)
  83 {
  84
  85         return (PAM_SUCCESS);
  86 }
  87
  88 PAM_MODULE_ENTRY("pam_self");