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_authtok.c 807 2014-09-09 09:41:32Z 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 #include <string.h>
46
47 #include <security/pam_appl.h>
48 #include <security/openpam.h>
49
50 #include "openpam_impl.h"
51 #include "openpam_strlset.h"
52
53 static const char authtok_prompt[] = "Password:";
54 static const char authtok_prompt_remote[] = "Password for %u@%h:";
55 static const char oldauthtok_prompt[] = "Old Password:";
56 static const char newauthtok_prompt[] = "New Password:";
57
58 /*
59 * OpenPAM extension
60 *
61 * Retrieve authentication token
62 */
63
64 int
pam_get_authtok(pam_handle_t * pamh,int item,const char ** authtok,const char * prompt)65 pam_get_authtok(pam_handle_t *pamh,
66 int item,
67 const char **authtok,
68 const char *prompt)
69 {
70 char prompt_buf[1024];
71 size_t prompt_size;
72 const void *oldauthtok, *prevauthtok, *promptp;
73 const char *prompt_option, *default_prompt;
74 const void *lhost, *rhost;
75 char *resp, *resp2;
76 int pitem, r, style, twice;
77
78 ENTER();
79 if (pamh == NULL || authtok == NULL)
80 RETURNC(PAM_SYSTEM_ERR);
81 *authtok = NULL;
82 twice = 0;
83 switch (item) {
84 case PAM_AUTHTOK:
85 pitem = PAM_AUTHTOK_PROMPT;
86 prompt_option = "authtok_prompt";
87 default_prompt = authtok_prompt;
88 r = pam_get_item(pamh, PAM_RHOST, &rhost);
89 if (r == PAM_SUCCESS && rhost != NULL) {
90 r = pam_get_item(pamh, PAM_HOST, &lhost);
91 if (r == PAM_SUCCESS && lhost != NULL) {
92 if (strcmp(rhost, lhost) != 0)
93 default_prompt = authtok_prompt_remote;
94 }
95 }
96 r = pam_get_item(pamh, PAM_OLDAUTHTOK, &oldauthtok);
97 if (r == PAM_SUCCESS && oldauthtok != NULL) {
98 default_prompt = newauthtok_prompt;
99 twice = 1;
100 }
101 break;
102 case PAM_OLDAUTHTOK:
103 pitem = PAM_OLDAUTHTOK_PROMPT;
104 prompt_option = "oldauthtok_prompt";
105 default_prompt = oldauthtok_prompt;
106 twice = 0;
107 break;
108 default:
109 RETURNC(PAM_SYMBOL_ERR);
110 }
111 if (openpam_get_option(pamh, "try_first_pass") ||
112 openpam_get_option(pamh, "use_first_pass")) {
113 r = pam_get_item(pamh, item, &prevauthtok);
114 if (r == PAM_SUCCESS && prevauthtok != NULL) {
115 *authtok = prevauthtok;
116 RETURNC(PAM_SUCCESS);
117 } else if (openpam_get_option(pamh, "use_first_pass")) {
118 RETURNC(r == PAM_SUCCESS ? PAM_AUTH_ERR : r);
119 }
120 }
121 /* pam policy overrides the module's choice */
122 if ((promptp = openpam_get_option(pamh, prompt_option)) != NULL)
123 prompt = promptp;
124 /* no prompt provided, see if there is one tucked away somewhere */
125 if (prompt == NULL) {
126 r = pam_get_item(pamh, pitem, &promptp);
127 if (r == PAM_SUCCESS && promptp != NULL)
128 prompt = promptp;
129 }
130 /* fall back to hardcoded default */
131 if (prompt == NULL)
132 prompt = default_prompt;
133 /* expand */
134 prompt_size = sizeof prompt_buf;
135 r = openpam_subst(pamh, prompt_buf, &prompt_size, prompt);
136 if (r == PAM_SUCCESS && prompt_size <= sizeof prompt_buf)
137 prompt = prompt_buf;
138 style = openpam_get_option(pamh, "echo_pass") ?
139 PAM_PROMPT_ECHO_ON : PAM_PROMPT_ECHO_OFF;
140 r = pam_prompt(pamh, style, &resp, "%s", prompt);
141 if (r != PAM_SUCCESS)
142 RETURNC(r);
143 if (twice) {
144 r = pam_prompt(pamh, style, &resp2, "Retype %s", prompt);
145 if (r != PAM_SUCCESS) {
146 strlset(resp, 0, PAM_MAX_RESP_SIZE);
147 FREE(resp);
148 RETURNC(r);
149 }
150 if (strcmp(resp, resp2) != 0) {
151 strlset(resp, 0, PAM_MAX_RESP_SIZE);
152 FREE(resp);
153 }
154 strlset(resp2, 0, PAM_MAX_RESP_SIZE);
155 FREE(resp2);
156 }
157 if (resp == NULL)
158 RETURNC(PAM_TRY_AGAIN);
159 r = pam_set_item(pamh, item, resp);
160 strlset(resp, 0, PAM_MAX_RESP_SIZE);
161 FREE(resp);
162 if (r != PAM_SUCCESS)
163 RETURNC(r);
164 r = pam_get_item(pamh, item, (const void **)authtok);
165 RETURNC(r);
166 }
167
168 /*
169 * Error codes:
170 *
171 * =pam_get_item
172 * =pam_prompt
173 * =pam_set_item
174 * !PAM_SYMBOL_ERR
175 * PAM_TRY_AGAIN
176 */
177
178 /**
179 * The =pam_get_authtok function either prompts the user for an
180 * authentication token or retrieves a cached authentication token,
181 * depending on circumstances.
182 * Either way, a pointer to the authentication token is stored in the
183 * location pointed to by the =authtok argument, and the corresponding PAM
184 * item is updated.
185 *
186 * The =item argument must have one of the following values:
187 *
188 * =PAM_AUTHTOK:
189 * Returns the current authentication token, or the new token
190 * when changing authentication tokens.
191 * =PAM_OLDAUTHTOK:
192 * Returns the previous authentication token when changing
193 * authentication tokens.
194 *
195 * The =prompt argument specifies a prompt to use if no token is cached.
196 * If it is =NULL, the =PAM_AUTHTOK_PROMPT or =PAM_OLDAUTHTOK_PROMPT item,
197 * as appropriate, will be used.
198 * If that item is also =NULL, a hardcoded default prompt will be used.
199 * Additionally, when =pam_get_authtok is called from a service module,
200 * the prompt may be affected by module options as described below.
201 * The prompt is then expanded using =openpam_subst before it is passed to
202 * the conversation function.
203 *
204 * If =item is set to =PAM_AUTHTOK and there is a non-null =PAM_OLDAUTHTOK
205 * item, =pam_get_authtok will ask the user to confirm the new token by
206 * retyping it.
207 * If there is a mismatch, =pam_get_authtok will return =PAM_TRY_AGAIN.
208 *
209 * MODULE OPTIONS
210 *
211 * When called by a service module, =pam_get_authtok will recognize the
212 * following module options:
213 *
214 * ;authtok_prompt:
215 * Prompt to use when =item is set to =PAM_AUTHTOK.
216 * This option overrides both the =prompt argument and the
217 * =PAM_AUTHTOK_PROMPT item.
218 * ;echo_pass:
219 * If the application's conversation function allows it, this
220 * lets the user see what they are typing.
221 * This should only be used for non-reusable authentication
222 * tokens.
223 * ;oldauthtok_prompt:
224 * Prompt to use when =item is set to =PAM_OLDAUTHTOK.
225 * This option overrides both the =prompt argument and the
226 * =PAM_OLDAUTHTOK_PROMPT item.
227 * ;try_first_pass:
228 * If the requested item is non-null, return it without
229 * prompting the user.
230 * Typically, the service module will verify the token, and
231 * if it does not match, clear the item before calling
232 * =pam_get_authtok a second time.
233 * ;use_first_pass:
234 * Do not prompt the user at all; just return the cached
235 * value, or =PAM_AUTH_ERR if there is none.
236 *
237 * >pam_conv
238 * >pam_get_item
239 * >pam_get_user
240 * >openpam_get_option
241 * >openpam_subst
242 */
243