lib/libpam/modules/pam_guest/pam_guest.c

   1 /*-
   2  * SPDX-License-Identifier: BSD-3-Clause
   3  *
   4  * Copyright (c) 2003 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: head/lib/libpam/modules/pam_guest/pam_guest.c 326219 2017-11-26 02:00:33Z pfg $
  37  */
  38
  39 #include <string.h>
  40
  41 #define PAM_SM_AUTH
  42
  43 #include <security/pam_appl.h>
  44 #include <security/pam_modules.h>
  45 #include <security/openpam.h>
  46
  47 #define DEFAULT_GUESTS  "guest"
  48
  49 static int
  50 lookup(const char *str, const char *list)
  51 {
  52         const char *next;
  53         size_t len;
  54
  55         len = strlen(str);
  56         while (*list != '\0') {
  57                 while (*list == ',')
  58                         ++list;
  59                 if ((next = strchr(list, ',')) == NULL)
  60                         next = strchr(list, '\0');
  61                 if (next - list == (ptrdiff_t)len &&
  62                     strncmp(list, str, len) == 0)
  63                         return (1);
  64                 list = next;
  65         }
  66         return (0);
  67 }
  68
  69 PAM_EXTERN int
  70 pam_sm_authenticate(pam_handle_t *pamh, int flags __unused,
  71     int argc __unused, const char *argv[] __unused)
  72 {
  73         const char *authtok, *guests, *user;
  74         int err, is_guest;
  75
  76         /* get target account */
  77         if (pam_get_user(pamh, &user, NULL) != PAM_SUCCESS || user == NULL)
  78                 return (PAM_AUTH_ERR);
  79
  80         /* get list of guest logins */
  81         if ((guests = openpam_get_option(pamh, "guests")) == NULL)
  82                 guests = DEFAULT_GUESTS;
  83
  84         /* check if the target account is on the list */
  85         is_guest = lookup(user, guests);
  86
  87         /* check password */
  88         if (!openpam_get_option(pamh, "nopass")) {
  89                 err = pam_get_authtok(pamh, PAM_AUTHTOK, &authtok, NULL);
  90                 if (err != PAM_SUCCESS)
  91                         return (err);
  92                 if (openpam_get_option(pamh, "pass_is_user") &&
  93                     strcmp(user, authtok) != 0)
  94                         return (PAM_AUTH_ERR);
  95                 if (openpam_get_option(pamh, "pass_as_ruser"))
  96                         pam_set_item(pamh, PAM_RUSER, authtok);
  97         }
  98
  99         /* done */
 100         if (is_guest) {
 101                 pam_setenv(pamh, "GUEST", user, 1);
 102                 return (PAM_SUCCESS);
 103         }
 104         return (PAM_AUTH_ERR);
 105 }
 106
 107 PAM_EXTERN int
 108 pam_sm_setcred(pam_handle_t * pamh __unused, int flags __unused,
 109     int argc __unused, const char *argv[] __unused)
 110 {
 111
 112         return (PAM_SUCCESS);
 113 }
 114
 115 PAM_MODULE_ENTRY("pam_guest");