pam_get_user.c revision 315907 
1/*-
2 * Copyright (c) 2002-2003 Networks Associates Technology, Inc.
3 * Copyright (c) 2004-2011 Dag-Erling Sm��rgrav
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		r = pam_get_item(pamh, PAM_USER_PROMPT, &promptp);
83		if (r == PAM_SUCCESS && promptp != NULL)
84			prompt = promptp;
85	}
86	/* fall back to hardcoded default */
87	if (prompt == NULL)
88		prompt = user_prompt;
89	/* expand */
90	prompt_size = sizeof prompt_buf;
91	r = openpam_subst(pamh, prompt_buf, &prompt_size, prompt);
92	if (r == PAM_SUCCESS && prompt_size <= sizeof prompt_buf)
93		prompt = prompt_buf;
94	r = pam_prompt(pamh, PAM_PROMPT_ECHO_ON, &resp, "%s", prompt);
95	if (r != PAM_SUCCESS)
96		RETURNC(r);
97	r = pam_set_item(pamh, PAM_USER, resp);
98	FREE(resp);
99	if (r != PAM_SUCCESS)
100		RETURNC(r);
101	r = pam_get_item(pamh, PAM_USER, (const void **)user);
102	RETURNC(r);
103}
104
105/*
106 * Error codes:
107 *
108 *	=pam_get_item
109 *	=pam_prompt
110 *	=pam_set_item
111 *	!PAM_SYMBOL_ERR
112 */
113
114/**
115 * The =pam_get_user function returns the name of the target user, as
116 * specified to =pam_start.
117 * If no user was specified, nor set using =pam_set_item, =pam_get_user
118 * will prompt for a user name.
119 * Either way, a pointer to the user name is stored in the location
120 * pointed to by the =user argument, and the corresponding PAM item is
121 * updated.
122 *
123 * The =prompt argument specifies a prompt to use if no user name is
124 * cached.
125 * If it is =NULL, the =PAM_USER_PROMPT item will be used.
126 * If that item is also =NULL, a hardcoded default prompt will be used.
127 * Additionally, when =pam_get_user is called from a service module, the
128 * prompt may be affected by module options as described below.
129 * The prompt is then expanded using =openpam_subst before it is passed to
130 * the conversation function.
131 *
132 * MODULE OPTIONS
133 *
134 * When called by a service module, =pam_get_user will recognize the
135 * following module options:
136 *
137 *	;user_prompt:
138 *		Prompt to use when asking for the user name.
139 *		This option overrides both the =prompt argument and the
140 *		=PAM_USER_PROMPT item.
141 *
142 * >pam_conv
143 * >pam_get_item
144 * >pam_get_authtok
145 * >openpam_get_option
146 * >openpam_subst
147 */
148