contrib/openpam/lib/pam_get_user.c

   1 /*-
   2  * Copyright (c) 2002-2003 Networks Associates Technology, Inc.
   3  * Copyright (c) 2004-2011 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_user.c 455 2011-10-29 18:31:11Z des $
  36  */
  37
  38 #ifdef HAVE_CONFIG_H
  39 # include "config.h"
  40 #endif
  41
  42 #include <sys/param.h>
  43
  44 #include <stdlib.h>
  45
  46 #include <security/pam_appl.h>
  47 #include <security/openpam.h>
  48
  49 #include "openpam_impl.h"
  50
  51 static const char user_prompt[] = "Login:";
  52
  53 /*
  54  * XSSO 4.2.1
  55  * XSSO 6 page 52
  56  *
  57  * Retrieve user name
  58  */
  59
  60 int
  61 pam_get_user(pam_handle_t *pamh,
  62         const char **user,
  63         const char *prompt)
  64 {
  65         char prompt_buf[1024];
  66         size_t prompt_size;
  67         const void *promptp;
  68         char *resp;
  69         int r;
  70
  71         ENTER();
  72         if (pamh == NULL || user == NULL)
  73                 RETURNC(PAM_SYSTEM_ERR);
  74         r = pam_get_item(pamh, PAM_USER, (const void **)user);
  75         if (r == PAM_SUCCESS && *user != NULL)
  76                 RETURNC(PAM_SUCCESS);
  77         /* pam policy overrides the module's choice */
  78         if ((promptp = openpam_get_option(pamh, "user_prompt")) != NULL)
  79                 prompt = promptp;
  80         /* no prompt provided, see if there is one tucked away somewhere */
  81         if (prompt == NULL)
  82                 if (pam_get_item(pamh, PAM_USER_PROMPT, &promptp) &&
  83                     promptp != NULL)
  84                         prompt = promptp;
  85         /* fall back to hardcoded default */
  86         if (prompt == NULL)
  87                 prompt = user_prompt;
  88         /* expand */
  89         prompt_size = sizeof prompt_buf;
  90         r = openpam_subst(pamh, prompt_buf, &prompt_size, prompt);
  91         if (r == PAM_SUCCESS && prompt_size <= sizeof prompt_buf)
  92                 prompt = prompt_buf;
  93         r = pam_prompt(pamh, PAM_PROMPT_ECHO_ON, &resp, "%s", prompt);
  94         if (r != PAM_SUCCESS)
  95                 RETURNC(r);
  96         r = pam_set_item(pamh, PAM_USER, resp);
  97         FREE(resp);
  98         if (r != PAM_SUCCESS)
  99                 RETURNC(r);
 100         r = pam_get_item(pamh, PAM_USER, (const void **)user);
 101         RETURNC(r);
 102 }
 103
 104 /*
 105  * Error codes:
 106  *
 107  *      =pam_get_item
 108  *      =pam_prompt
 109  *      =pam_set_item
 110  *      !PAM_SYMBOL_ERR
 111  */
 112
 113 /**
 114  * The =pam_get_user function returns the name of the target user, as
 115  * specified to =pam_start.
 116  * If no user was specified, nor set using =pam_set_item, =pam_get_user
 117  * will prompt for a user name.
 118  * Either way, a pointer to the user name is stored in the location
 119  * pointed to by the =user argument.
 120  *
 121  * The =prompt argument specifies a prompt to use if no user name is
 122  * cached.
 123  * If it is =NULL, the =PAM_USER_PROMPT item will be used.
 124  * If that item is also =NULL, a hardcoded default prompt will be used.
 125  * Either way, the prompt is expanded using =openpam_subst before it is
 126  * passed to the conversation function.
 127  *
 128  * If =pam_get_user is called from a module and the ;user_prompt option is
 129  * set in the policy file, the value of that option takes precedence over
 130  * both the =prompt argument and the =PAM_USER_PROMPT item.
 131  *
 132  * >pam_get_item
 133  * >pam_get_authtok
 134  * >openpam_subst
 135  */