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 670 2013-03-17 19:26:07Z 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
51static const char user_prompt[] = "Login:";
52
53/*
54 * XSSO 4.2.1
55 * XSSO 6 page 52
56 *
57 * Retrieve user name
58 */
59
60int
61pam_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, and the corresponding PAM item is
120 * updated.
121 *
122 * The =prompt argument specifies a prompt to use if no user name is
123 * cached.
124 * If it is =NULL, the =PAM_USER_PROMPT item will be used.
125 * If that item is also =NULL, a hardcoded default prompt will be used.
126 * Additionally, when =pam_get_user is called from a service module, the
127 * prompt may be affected by module options as described below.
128 * The prompt is then expanded using =openpam_subst before it is passed to
129 * the conversation function.
130 *
131 * MODULE OPTIONS
132 *
133 * When called by a service module, =pam_get_user will recognize the
134 * following module options:
135 *
136 *	;user_prompt:
137 *		Prompt to use when asking for the user name.
138 *		This option overrides both the =prompt argument and the
139 *		=PAM_USER_PROMPT item.
140 *
141 * >pam_conv
142 * >pam_get_item
143 * >pam_get_authtok
144 * >openpam_get_option
145 * >openpam_subst
146 */
147