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