dist/openpam/lib/pam_get_authtok.c

   1 /*-
   2  * Copyright (c) 2002-2003 Networks Associates Technology, Inc.
   3  * Copyright (c) 2004-2007 Dag-Erling Smørgrav
   4  * All rights reserved.
   5  *
   6  * This software was developed for the FreeBSD Project by ThinkSec AS and
   7  * Network Associates Laboratories, the Security Research Division of
   8  * Network Associates, Inc.  under DARPA/SPAWAR contract N66001-01-C-8035
   9  * ("CBOSS"), as part of the DARPA CHATS research program.
  10  *
  11  * Redistribution and use in source and binary forms, with or without
  12  * modification, are permitted provided that the following conditions
  13  * are met:
  14  * 1. Redistributions of source code must retain the above copyright
  15  *    notice, this list of conditions and the following disclaimer.
  16  * 2. Redistributions in binary form must reproduce the above copyright
  17  *    notice, this list of conditions and the following disclaimer in the
  18  *    documentation and/or other materials provided with the distribution.
  19  * 3. The name of the author may not be used to endorse or promote
  20  *    products derived from this software without specific prior written
  21  *    permission.
  22  *
  23  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  24  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  26  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  27  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  28  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  29  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  30  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  31  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  32  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  33  * SUCH DAMAGE.
  34  *
  35  * $Id: pam_get_authtok.c,v 1.5 2008/07/16 18:20:17 drochner Exp $
  36  */
  37
  38 #include <sys/param.h>
  39
  40 #include <stdlib.h>
  41 #include <string.h>
  42
  43 #include <security/pam_appl.h>
  44 #include <security/openpam.h>
  45
  46 #include "openpam_impl.h"
  47
  48 static const char authtok_prompt[] = "Password:";
  49 static const char oldauthtok_prompt[] = "Old Password:";
  50 static const char newauthtok_prompt[] = "New Password:";
  51
  52 /*
  53  * OpenPAM extension
  54  *
  55  * Retrieve authentication token
  56  */
  57
  58 int
  59 pam_get_authtok(pam_handle_t *pamh,
  60         int item,
  61         const char **authtok,
  62         const char *prompt)
  63 {
  64         const void *oldauthtok, *prevauthtok, *promptp;
  65         const char *default_prompt;
  66         char *resp, *resp2;
  67         int pitem, r, style, twice;
  68
  69         ENTER();
  70         if (pamh == NULL || authtok == NULL)
  71                 RETURNC(PAM_SYSTEM_ERR);
  72         *authtok = NULL;
  73         twice = 0;
  74         switch (item) {
  75         case PAM_AUTHTOK:
  76                 pitem = PAM_AUTHTOK_PROMPT;
  77                 default_prompt = authtok_prompt;
  78                 r = pam_get_item(pamh, PAM_OLDAUTHTOK, &oldauthtok);
  79                 if (r == PAM_SUCCESS && oldauthtok != NULL) {
  80                         default_prompt = newauthtok_prompt;
  81                         twice = 1;
  82                 }
  83                 break;
  84         case PAM_OLDAUTHTOK:
  85                 pitem = PAM_OLDAUTHTOK_PROMPT;
  86                 default_prompt = oldauthtok_prompt;
  87                 twice = 0;
  88                 break;
  89         default:
  90                 RETURNC(PAM_SYMBOL_ERR);
  91         }
  92         if (openpam_get_option(pamh, "try_first_pass") ||
  93             openpam_get_option(pamh, "use_first_pass")) {
  94                 r = pam_get_item(pamh, item, &prevauthtok);
  95                 if (r == PAM_SUCCESS && prevauthtok != NULL) {
  96                         *authtok = prevauthtok;
  97                         RETURNC(PAM_SUCCESS);
  98                 }
  99                 else if (openpam_get_option(pamh, "use_first_pass"))
 100                         RETURNC(r == PAM_SUCCESS ? PAM_AUTH_ERR : r);
 101         }
 102         if (prompt == NULL) {
 103                 r = pam_get_item(pamh, pitem, &promptp);
 104                 if (r != PAM_SUCCESS || promptp == NULL)
 105                         prompt = default_prompt;
 106                 else
 107                         prompt = promptp;
 108         }
 109         style = openpam_get_option(pamh, "echo_pass") ?
 110             PAM_PROMPT_ECHO_ON : PAM_PROMPT_ECHO_OFF;
 111         r = pam_prompt(pamh, style, &resp, "%s", prompt);
 112         if (r != PAM_SUCCESS)
 113                 RETURNC(r);
 114         if (twice) {
 115                 r = pam_prompt(pamh, style, &resp2, "Retype %s", prompt);
 116                 if (r != PAM_SUCCESS) {
 117                         memset(resp, 0, strlen(resp));
 118                         FREE(resp);
 119                         RETURNC(r);
 120                 }
 121                 if (strcmp(resp, resp2) != 0) {
 122                         memset(resp, 0, strlen(resp));
 123                         FREE(resp);
 124                 }
 125                 memset(resp2, 0, strlen(resp2));
 126                 FREE(resp2);
 127         }
 128         if (resp == NULL)
 129                 RETURNC(PAM_TRY_AGAIN);
 130         r = pam_set_item(pamh, item, resp);
 131         memset(resp, 0, strlen(resp));
 132         FREE(resp);
 133         if (r != PAM_SUCCESS)
 134                 RETURNC(r);
 135         r = pam_get_item(pamh, item, (const void **)authtok);
 136         RETURNC(r);
 137         /*NOTREACHED*/
 138 }
 139
 140 /*
 141  * Error codes:
 142  *
 143  *      =pam_get_item
 144  *      =pam_prompt
 145  *      =pam_set_item
 146  *      !PAM_SYMBOL_ERR
 147  *      PAM_TRY_AGAIN
 148  */
 149
 150 /**
 151  * The =pam_get_authtok function returns the cached authentication token,
 152  * or prompts the user if no token is currently cached.
 153  * Either way, a pointer to the authentication token is stored in the
 154  * location pointed to by the =authtok argument.
 155  *
 156  * The =item argument must have one of the following values:
 157  *
 158  *      =PAM_AUTHTOK:
 159  *              Returns the current authentication token, or the new token
 160  *              when changing authentication tokens.
 161  *      =PAM_OLDAUTHTOK:
 162  *              Returns the previous authentication token when changing
 163  *              authentication tokens.
 164  *
 165  * The =prompt argument specifies a prompt to use if no token is cached.
 166  * If it is =NULL, the =PAM_AUTHTOK_PROMPT or =PAM_OLDAUTHTOK_PROMPT item,
 167  * as appropriate, will be used.
 168  * If that item is also =NULL, a hardcoded default prompt will be used.
 169  *
 170  * If =item is set to =PAM_AUTHTOK and there is a non-null =PAM_OLDAUTHTOK
 171  * item, =pam_get_authtok will ask the user to confirm the new token by
 172  * retyping it.
 173  * If there is a mismatch, =pam_get_authtok will return =PAM_TRY_AGAIN.
 174  *
 175  * >pam_get_item
 176  * >pam_get_user
 177  */