1 /* $NetBSD: pam_get_authtok.c,v 1.5 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_authtok.c,v 1.5 2023/06/30 21:46:21 christos Exp $"); 44 45 #include <sys/param.h> 46 47 #include <stdlib.h> 48 #include <string.h> 49 50 #include <security/pam_appl.h> 51 #include <security/openpam.h> 52 53 #include "openpam_impl.h" 54 #include "openpam_strlset.h" 55 56 static const char authtok_prompt[] = "Password:"; 57 static const char authtok_prompt_remote[] = "Password for %u@%h:"; 58 static const char oldauthtok_prompt[] = "Old Password:"; 59 static const char newauthtok_prompt[] = "New Password:"; 60 61 /* 62 * OpenPAM extension 63 * 64 * Retrieve authentication token 65 */ 66 67 int 68 pam_get_authtok(pam_handle_t *pamh, 69 int item, 70 const char **authtok, 71 const char *prompt) 72 { 73 char prompt_buf[1024]; 74 size_t prompt_size; 75 const void *oldauthtok, *prevauthtok, *promptp; 76 const char *prompt_option, *default_prompt; 77 const void *lhost, *rhost; 78 char *resp, *resp2; 79 int pitem, r, style, twice; 80 81 ENTER(); 82 *authtok = NULL; 83 twice = 0; 84 switch ((enum openpam_item_primitives)item) { 85 case PAM_AUTHTOK: 86 pitem = PAM_AUTHTOK_PROMPT; 87 prompt_option = "authtok_prompt"; 88 default_prompt = authtok_prompt; 89 r = pam_get_item(pamh, PAM_RHOST, &rhost); 90 if (r == PAM_SUCCESS && rhost != NULL) { 91 r = pam_get_item(pamh, PAM_HOST, &lhost); 92 if (r == PAM_SUCCESS && lhost != NULL) { 93 if (strcmp(rhost, lhost) != 0) 94 default_prompt = authtok_prompt_remote; 95 } 96 } 97 r = pam_get_item(pamh, PAM_OLDAUTHTOK, &oldauthtok); 98 if (r == PAM_SUCCESS && oldauthtok != NULL) { 99 default_prompt = newauthtok_prompt; 100 twice = 1; 101 } 102 break; 103 case PAM_OLDAUTHTOK: 104 pitem = PAM_OLDAUTHTOK_PROMPT; 105 prompt_option = "oldauthtok_prompt"; 106 default_prompt = oldauthtok_prompt; 107 twice = 0; 108 break; 109 default: 110 RETURNC(PAM_BAD_CONSTANT); 111 } 112 if (openpam_get_option(pamh, "try_first_pass") || 113 openpam_get_option(pamh, "use_first_pass")) { 114 r = pam_get_item(pamh, item, &prevauthtok); 115 if (r == PAM_SUCCESS && prevauthtok != NULL) { 116 *authtok = prevauthtok; 117 RETURNC(PAM_SUCCESS); 118 } else if (openpam_get_option(pamh, "use_first_pass")) { 119 RETURNC(r == PAM_SUCCESS ? PAM_AUTH_ERR : r); 120 } 121 } 122 /* pam policy overrides the module's choice */ 123 if ((promptp = openpam_get_option(pamh, prompt_option)) != NULL) 124 prompt = promptp; 125 /* no prompt provided, see if there is one tucked away somewhere */ 126 if (prompt == NULL) { 127 r = pam_get_item(pamh, pitem, &promptp); 128 if (r == PAM_SUCCESS && promptp != NULL) 129 prompt = promptp; 130 } 131 /* fall back to hardcoded default */ 132 if (prompt == NULL) 133 prompt = default_prompt; 134 /* expand */ 135 prompt_size = sizeof prompt_buf; 136 r = openpam_subst(pamh, prompt_buf, &prompt_size, prompt); 137 if (r == PAM_SUCCESS && prompt_size <= sizeof prompt_buf) 138 prompt = prompt_buf; 139 style = openpam_get_option(pamh, "echo_pass") ? 140 PAM_PROMPT_ECHO_ON : PAM_PROMPT_ECHO_OFF; 141 r = pam_prompt(pamh, style, &resp, "%s", prompt); 142 if (r != PAM_SUCCESS) 143 RETURNC(r); 144 if (twice) { 145 r = pam_prompt(pamh, style, &resp2, "Retype %s", prompt); 146 if (r != PAM_SUCCESS) { 147 strlset(resp, 0, PAM_MAX_RESP_SIZE); 148 FREE(resp); 149 RETURNC(r); 150 } 151 if (strcmp(resp, resp2) != 0) { 152 strlset(resp, 0, PAM_MAX_RESP_SIZE); 153 FREE(resp); 154 } 155 strlset(resp2, 0, PAM_MAX_RESP_SIZE); 156 FREE(resp2); 157 } 158 if (resp == NULL) 159 RETURNC(PAM_TRY_AGAIN); 160 r = pam_set_item(pamh, item, resp); 161 strlset(resp, 0, PAM_MAX_RESP_SIZE); 162 FREE(resp); 163 if (r != PAM_SUCCESS) 164 RETURNC(r); 165 r = pam_get_item(pamh, item, (const void **)authtok); 166 RETURNC(r); 167 } 168 169 /* 170 * Error codes: 171 * 172 * =pam_get_item 173 * =pam_prompt 174 * =pam_set_item 175 * !PAM_SYMBOL_ERR 176 * PAM_BAD_CONSTANT 177 * PAM_TRY_AGAIN 178 */ 179 180 /** 181 * The =pam_get_authtok function either prompts the user for an 182 * authentication token or retrieves a cached authentication token, 183 * depending on circumstances. 184 * Either way, a pointer to the authentication token is stored in the 185 * location pointed to by the =authtok argument, and the corresponding PAM 186 * item is updated. 187 * 188 * The =item argument must have one of the following values: 189 * 190 * =PAM_AUTHTOK: 191 * Returns the current authentication token, or the new token 192 * when changing authentication tokens. 193 * =PAM_OLDAUTHTOK: 194 * Returns the previous authentication token when changing 195 * authentication tokens. 196 * 197 * The =prompt argument specifies a prompt to use if no token is cached. 198 * If it is =NULL, the =PAM_AUTHTOK_PROMPT or =PAM_OLDAUTHTOK_PROMPT item, 199 * as appropriate, will be used. 200 * If that item is also =NULL, a hardcoded default prompt will be used. 201 * Additionally, when =pam_get_authtok is called from a service module, 202 * the prompt may be affected by module options as described below. 203 * The prompt is then expanded using =openpam_subst before it is passed to 204 * the conversation function. 205 * 206 * If =item is set to =PAM_AUTHTOK and there is a non-null =PAM_OLDAUTHTOK 207 * item, =pam_get_authtok will ask the user to confirm the new token by 208 * retyping it. 209 * If there is a mismatch, =pam_get_authtok will return =PAM_TRY_AGAIN. 210 * 211 * MODULE OPTIONS 212 * 213 * When called by a service module, =pam_get_authtok will recognize the 214 * following module options: 215 * 216 * ;authtok_prompt: 217 * Prompt to use when =item is set to =PAM_AUTHTOK. 218 * This option overrides both the =prompt argument and the 219 * =PAM_AUTHTOK_PROMPT item. 220 * ;echo_pass: 221 * If the application's conversation function allows it, this 222 * lets the user see what they are typing. 223 * This should only be used for non-reusable authentication 224 * tokens. 225 * ;oldauthtok_prompt: 226 * Prompt to use when =item is set to =PAM_OLDAUTHTOK. 227 * This option overrides both the =prompt argument and the 228 * =PAM_OLDAUTHTOK_PROMPT item. 229 * ;try_first_pass: 230 * If the requested item is non-null, return it without 231 * prompting the user. 232 * Typically, the service module will verify the token, and 233 * if it does not match, clear the item before calling 234 * =pam_get_authtok a second time. 235 * ;use_first_pass: 236 * Do not prompt the user at all; just return the cached 237 * value, or =PAM_AUTH_ERR if there is none. 238 * 239 * >pam_conv 240 * >pam_get_item 241 * >pam_get_user 242 * >openpam_get_option 243 * >openpam_subst 244 */ 245