1 /* $NetBSD: pam_get_user.c,v 1.4 2023/06/30 21:46:21 christos Exp $ */
2
3 /*-
4 * Copyright (c) 2002-2003 Networks Associates Technology, Inc.
5 * Copyright (c) 2004-2017 Dag-Erling Smørgrav
6 * All rights reserved.
7 *
8 * This software was developed for the FreeBSD Project by ThinkSec AS and
9 * Network Associates Laboratories, the Security Research Division of
10 * Network Associates, Inc. under DARPA/SPAWAR contract N66001-01-C-8035
11 * ("CBOSS"), as part of the DARPA CHATS research program.
12 *
13 * Redistribution and use in source and binary forms, with or without
14 * modification, are permitted provided that the following conditions
15 * are met:
16 * 1. Redistributions of source code must retain the above copyright
17 * notice, this list of conditions and the following disclaimer.
18 * 2. Redistributions in binary form must reproduce the above copyright
19 * notice, this list of conditions and the following disclaimer in the
20 * documentation and/or other materials provided with the distribution.
21 * 3. The name of the author may not be used to endorse or promote
22 * products derived from this software without specific prior written
23 * permission.
24 *
25 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
27 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
28 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
29 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
30 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
31 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
32 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
33 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
34 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
35 * SUCH DAMAGE.
36 */
37
38 #ifdef HAVE_CONFIG_H
39 # include "config.h"
40 #endif
41
42 #include <sys/cdefs.h>
43 __RCSID("$NetBSD: pam_get_user.c,v 1.4 2023/06/30 21:46:21 christos Exp $");
44
45 #include <sys/param.h>
46
47 #include <stdlib.h>
48
49 #include <security/pam_appl.h>
50 #include <security/openpam.h>
51
52 #include "openpam_impl.h"
53
54 static const char user_prompt[] = "Login:";
55
56 /*
57 * XSSO 4.2.1
58 * XSSO 6 page 52
59 *
60 * Retrieve user name
61 */
62
63 int
pam_get_user(pam_handle_t * pamh,const char ** user,const char * prompt)64 pam_get_user(pam_handle_t *pamh,
65 const char **user,
66 const char *prompt)
67 {
68 char prompt_buf[1024];
69 size_t prompt_size;
70 const void *promptp;
71 char *resp;
72 int r;
73
74 ENTER();
75 r = pam_get_item(pamh, PAM_USER, (const void **)user);
76 if (r == PAM_SUCCESS && *user != NULL)
77 RETURNC(PAM_SUCCESS);
78 /* pam policy overrides the module's choice */
79 if ((promptp = openpam_get_option(pamh, "user_prompt")) != NULL)
80 prompt = promptp;
81 /* no prompt provided, see if there is one tucked away somewhere */
82 if (prompt == NULL) {
83 r = pam_get_item(pamh, PAM_USER_PROMPT, &promptp);
84 if (r == PAM_SUCCESS && promptp != NULL)
85 prompt = promptp;
86 }
87 /* fall back to hardcoded default */
88 if (prompt == NULL)
89 prompt = user_prompt;
90 /* expand */
91 prompt_size = sizeof prompt_buf;
92 r = openpam_subst(pamh, prompt_buf, &prompt_size, prompt);
93 if (r == PAM_SUCCESS && prompt_size <= sizeof prompt_buf)
94 prompt = prompt_buf;
95 r = pam_prompt(pamh, PAM_PROMPT_ECHO_ON, &resp, "%s", prompt);
96 if (r != PAM_SUCCESS)
97 RETURNC(r);
98 r = pam_set_item(pamh, PAM_USER, resp);
99 FREE(resp);
100 if (r != PAM_SUCCESS)
101 RETURNC(r);
102 r = pam_get_item(pamh, PAM_USER, (const void **)user);
103 RETURNC(r);
104 }
105
106 /*
107 * Error codes:
108 *
109 * =pam_get_item
110 * =pam_prompt
111 * =pam_set_item
112 * !PAM_SYMBOL_ERR
113 */
114
115 /**
116 * The =pam_get_user function returns the name of the target user, as
117 * specified to =pam_start.
118 * If no user was specified, nor set using =pam_set_item, =pam_get_user
119 * will prompt for a user name.
120 * Either way, a pointer to the user name is stored in the location
121 * pointed to by the =user argument, and the corresponding PAM item is
122 * updated.
123 *
124 * The =prompt argument specifies a prompt to use if no user name is
125 * cached.
126 * If it is =NULL, the =PAM_USER_PROMPT item will be used.
127 * If that item is also =NULL, a hardcoded default prompt will be used.
128 * Additionally, when =pam_get_user is called from a service module, the
129 * prompt may be affected by module options as described below.
130 * The prompt is then expanded using =openpam_subst before it is passed to
131 * the conversation function.
132 *
133 * MODULE OPTIONS
134 *
135 * When called by a service module, =pam_get_user will recognize the
136 * following module options:
137 *
138 * ;user_prompt:
139 * Prompt to use when asking for the user name.
140 * This option overrides both the =prompt argument and the
141 * =PAM_USER_PROMPT item.
142 *
143 * >pam_conv
144 * >pam_get_item
145 * >pam_get_authtok
146 * >openpam_get_option
147 * >openpam_subst
148 */
149