pam_get_authtok.c revision 348980
1/*- 2 * Copyright (c) 2002-2003 Networks Associates Technology, Inc. 3 * Copyright (c) 2004-2017 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 * $OpenPAM: pam_get_authtok.c 938 2017-04-30 21:34:42Z 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 53static const char authtok_prompt[] = "Password:"; 54static const char authtok_prompt_remote[] = "Password for %u@%h:"; 55static const char oldauthtok_prompt[] = "Old Password:"; 56static const char newauthtok_prompt[] = "New Password:"; 57 58/* 59 * OpenPAM extension 60 * 61 * Retrieve authentication token 62 */ 63 64int 65pam_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 *authtok = NULL; 80 twice = 0; 81 switch (item) { 82 case PAM_AUTHTOK: 83 pitem = PAM_AUTHTOK_PROMPT; 84 prompt_option = "authtok_prompt"; 85 default_prompt = authtok_prompt; 86 r = pam_get_item(pamh, PAM_RHOST, &rhost); 87 if (r == PAM_SUCCESS && rhost != NULL) { 88 r = pam_get_item(pamh, PAM_HOST, &lhost); 89 if (r == PAM_SUCCESS && lhost != NULL) { 90 if (strcmp(rhost, lhost) != 0) 91 default_prompt = authtok_prompt_remote; 92 } 93 } 94 r = pam_get_item(pamh, PAM_OLDAUTHTOK, &oldauthtok); 95 if (r == PAM_SUCCESS && oldauthtok != NULL) { 96 default_prompt = newauthtok_prompt; 97 twice = 1; 98 } 99 break; 100 case PAM_OLDAUTHTOK: 101 pitem = PAM_OLDAUTHTOK_PROMPT; 102 prompt_option = "oldauthtok_prompt"; 103 default_prompt = oldauthtok_prompt; 104 twice = 0; 105 break; 106 default: 107 RETURNC(PAM_BAD_CONSTANT); 108 } 109 if (openpam_get_option(pamh, "try_first_pass") || 110 openpam_get_option(pamh, "use_first_pass")) { 111 r = pam_get_item(pamh, item, &prevauthtok); 112 if (r == PAM_SUCCESS && prevauthtok != NULL) { 113 *authtok = prevauthtok; 114 RETURNC(PAM_SUCCESS); 115 } else if (openpam_get_option(pamh, "use_first_pass")) { 116 RETURNC(r == PAM_SUCCESS ? PAM_AUTH_ERR : r); 117 } 118 } 119 /* pam policy overrides the module's choice */ 120 if ((promptp = openpam_get_option(pamh, prompt_option)) != NULL) 121 prompt = promptp; 122 /* no prompt provided, see if there is one tucked away somewhere */ 123 if (prompt == NULL) { 124 r = pam_get_item(pamh, pitem, &promptp); 125 if (r == PAM_SUCCESS && promptp != NULL) 126 prompt = promptp; 127 } 128 /* fall back to hardcoded default */ 129 if (prompt == NULL) 130 prompt = default_prompt; 131 /* expand */ 132 prompt_size = sizeof prompt_buf; 133 r = openpam_subst(pamh, prompt_buf, &prompt_size, prompt); 134 if (r == PAM_SUCCESS && prompt_size <= sizeof prompt_buf) 135 prompt = prompt_buf; 136 style = openpam_get_option(pamh, "echo_pass") ? 137 PAM_PROMPT_ECHO_ON : PAM_PROMPT_ECHO_OFF; 138 r = pam_prompt(pamh, style, &resp, "%s", prompt); 139 if (r != PAM_SUCCESS) 140 RETURNC(r); 141 if (twice) { 142 r = pam_prompt(pamh, style, &resp2, "Retype %s", prompt); 143 if (r != PAM_SUCCESS) { 144 strlset(resp, 0, PAM_MAX_RESP_SIZE); 145 FREE(resp); 146 RETURNC(r); 147 } 148 if (strcmp(resp, resp2) != 0) { 149 strlset(resp, 0, PAM_MAX_RESP_SIZE); 150 FREE(resp); 151 } 152 strlset(resp2, 0, PAM_MAX_RESP_SIZE); 153 FREE(resp2); 154 } 155 if (resp == NULL) 156 RETURNC(PAM_TRY_AGAIN); 157 r = pam_set_item(pamh, item, resp); 158 strlset(resp, 0, PAM_MAX_RESP_SIZE); 159 FREE(resp); 160 if (r != PAM_SUCCESS) 161 RETURNC(r); 162 r = pam_get_item(pamh, item, (const void **)authtok); 163 RETURNC(r); 164} 165 166/* 167 * Error codes: 168 * 169 * =pam_get_item 170 * =pam_prompt 171 * =pam_set_item 172 * !PAM_SYMBOL_ERR 173 * PAM_BAD_CONSTANT 174 * PAM_TRY_AGAIN 175 */ 176 177/** 178 * The =pam_get_authtok function either prompts the user for an 179 * authentication token or retrieves a cached authentication token, 180 * depending on circumstances. 181 * Either way, a pointer to the authentication token is stored in the 182 * location pointed to by the =authtok argument, and the corresponding PAM 183 * item is updated. 184 * 185 * The =item argument must have one of the following values: 186 * 187 * =PAM_AUTHTOK: 188 * Returns the current authentication token, or the new token 189 * when changing authentication tokens. 190 * =PAM_OLDAUTHTOK: 191 * Returns the previous authentication token when changing 192 * authentication tokens. 193 * 194 * The =prompt argument specifies a prompt to use if no token is cached. 195 * If it is =NULL, the =PAM_AUTHTOK_PROMPT or =PAM_OLDAUTHTOK_PROMPT item, 196 * as appropriate, will be used. 197 * If that item is also =NULL, a hardcoded default prompt will be used. 198 * Additionally, when =pam_get_authtok is called from a service module, 199 * the prompt may be affected by module options as described below. 200 * The prompt is then expanded using =openpam_subst before it is passed to 201 * the conversation function. 202 * 203 * If =item is set to =PAM_AUTHTOK and there is a non-null =PAM_OLDAUTHTOK 204 * item, =pam_get_authtok will ask the user to confirm the new token by 205 * retyping it. 206 * If there is a mismatch, =pam_get_authtok will return =PAM_TRY_AGAIN. 207 * 208 * MODULE OPTIONS 209 * 210 * When called by a service module, =pam_get_authtok will recognize the 211 * following module options: 212 * 213 * ;authtok_prompt: 214 * Prompt to use when =item is set to =PAM_AUTHTOK. 215 * This option overrides both the =prompt argument and the 216 * =PAM_AUTHTOK_PROMPT item. 217 * ;echo_pass: 218 * If the application's conversation function allows it, this 219 * lets the user see what they are typing. 220 * This should only be used for non-reusable authentication 221 * tokens. 222 * ;oldauthtok_prompt: 223 * Prompt to use when =item is set to =PAM_OLDAUTHTOK. 224 * This option overrides both the =prompt argument and the 225 * =PAM_OLDAUTHTOK_PROMPT item. 226 * ;try_first_pass: 227 * If the requested item is non-null, return it without 228 * prompting the user. 229 * Typically, the service module will verify the token, and 230 * if it does not match, clear the item before calling 231 * =pam_get_authtok a second time. 232 * ;use_first_pass: 233 * Do not prompt the user at all; just return the cached 234 * value, or =PAM_AUTH_ERR if there is none. 235 * 236 * >pam_conv 237 * >pam_get_item 238 * >pam_get_user 239 * >openpam_get_option 240 * >openpam_subst 241 */ 242