1 /* 2 * Copyright (c) 2001 Markus Friedl. All rights reserved. 3 * Copyright (c) 2001 Per Allansson. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 15 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 16 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 17 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 18 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 19 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 20 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 21 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 22 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 23 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 24 */ 25 #include "includes.h" 26 RCSID("$OpenBSD: auth2-chall.c,v 1.24 2005/07/17 07:17:54 djm Exp $"); 27 RCSID("$FreeBSD$"); 28 29 #include "ssh2.h" 30 #include "auth.h" 31 #include "buffer.h" 32 #include "packet.h" 33 #include "xmalloc.h" 34 #include "dispatch.h" 35 #include "log.h" 36 #include "servconf.h" 37 38 /* import */ 39 extern ServerOptions options; 40 41 static int auth2_challenge_start(Authctxt *); 42 static int send_userauth_info_request(Authctxt *); 43 static void input_userauth_info_response(int, u_int32_t, void *); 44 45 #ifdef BSD_AUTH 46 extern KbdintDevice bsdauth_device; 47 #else 48 #ifdef USE_PAM 49 extern KbdintDevice sshpam_device; 50 #endif 51 #ifdef SKEY 52 extern KbdintDevice skey_device; 53 #endif 54 #endif 55 56 KbdintDevice *devices[] = { 57 #ifdef BSD_AUTH 58 &bsdauth_device, 59 #else 60 #ifdef USE_PAM 61 &sshpam_device, 62 #endif 63 #ifdef SKEY 64 &skey_device, 65 #endif 66 #endif 67 NULL 68 }; 69 70 typedef struct KbdintAuthctxt KbdintAuthctxt; 71 struct KbdintAuthctxt 72 { 73 char *devices; 74 void *ctxt; 75 KbdintDevice *device; 76 u_int nreq; 77 }; 78 79 #ifdef USE_PAM 80 void 81 remove_kbdint_device(const char *devname) 82 { 83 int i, j; 84 85 for (i = 0; devices[i] != NULL; i++) 86 if (strcmp(devices[i]->name, devname) == 0) { 87 for (j = i; devices[j] != NULL; j++) 88 devices[j] = devices[j+1]; 89 i--; 90 } 91 } 92 #endif 93 94 static KbdintAuthctxt * 95 kbdint_alloc(const char *devs) 96 { 97 KbdintAuthctxt *kbdintctxt; 98 Buffer b; 99 int i; 100 101 #ifdef USE_PAM 102 if (!options.use_pam) 103 remove_kbdint_device("pam"); 104 #endif 105 106 kbdintctxt = xmalloc(sizeof(KbdintAuthctxt)); 107 if (strcmp(devs, "") == 0) { 108 buffer_init(&b); 109 for (i = 0; devices[i]; i++) { 110 if (buffer_len(&b) > 0) 111 buffer_append(&b, ",", 1); 112 buffer_append(&b, devices[i]->name, 113 strlen(devices[i]->name)); 114 } 115 buffer_append(&b, "\0", 1); 116 kbdintctxt->devices = xstrdup(buffer_ptr(&b)); 117 buffer_free(&b); 118 } else { 119 kbdintctxt->devices = xstrdup(devs); 120 } 121 debug("kbdint_alloc: devices '%s'", kbdintctxt->devices); 122 kbdintctxt->ctxt = NULL; 123 kbdintctxt->device = NULL; 124 kbdintctxt->nreq = 0; 125 126 return kbdintctxt; 127 } 128 static void 129 kbdint_reset_device(KbdintAuthctxt *kbdintctxt) 130 { 131 if (kbdintctxt->ctxt) { 132 kbdintctxt->device->free_ctx(kbdintctxt->ctxt); 133 kbdintctxt->ctxt = NULL; 134 } 135 kbdintctxt->device = NULL; 136 } 137 static void 138 kbdint_free(KbdintAuthctxt *kbdintctxt) 139 { 140 if (kbdintctxt->device) 141 kbdint_reset_device(kbdintctxt); 142 if (kbdintctxt->devices) { 143 xfree(kbdintctxt->devices); 144 kbdintctxt->devices = NULL; 145 } 146 xfree(kbdintctxt); 147 } 148 /* get next device */ 149 static int 150 kbdint_next_device(KbdintAuthctxt *kbdintctxt) 151 { 152 size_t len; 153 char *t; 154 int i; 155 156 if (kbdintctxt->device) 157 kbdint_reset_device(kbdintctxt); 158 do { 159 len = kbdintctxt->devices ? 160 strcspn(kbdintctxt->devices, ",") : 0; 161 162 if (len == 0) 163 break; 164 for (i = 0; devices[i]; i++) 165 if (strncmp(kbdintctxt->devices, devices[i]->name, len) == 0) 166 kbdintctxt->device = devices[i]; 167 t = kbdintctxt->devices; 168 kbdintctxt->devices = t[len] ? xstrdup(t+len+1) : NULL; 169 xfree(t); 170 debug2("kbdint_next_device: devices %s", kbdintctxt->devices ? 171 kbdintctxt->devices : "<empty>"); 172 } while (kbdintctxt->devices && !kbdintctxt->device); 173 174 return kbdintctxt->device ? 1 : 0; 175 } 176 177 /* 178 * try challenge-response, set authctxt->postponed if we have to 179 * wait for the response. 180 */ 181 int 182 auth2_challenge(Authctxt *authctxt, char *devs) 183 { 184 debug("auth2_challenge: user=%s devs=%s", 185 authctxt->user ? authctxt->user : "<nouser>", 186 devs ? devs : "<no devs>"); 187 188 if (authctxt->user == NULL || !devs) 189 return 0; 190 if (authctxt->kbdintctxt == NULL) 191 authctxt->kbdintctxt = kbdint_alloc(devs); 192 return auth2_challenge_start(authctxt); 193 } 194 195 /* unregister kbd-int callbacks and context */ 196 void 197 auth2_challenge_stop(Authctxt *authctxt) 198 { 199 /* unregister callback */ 200 dispatch_set(SSH2_MSG_USERAUTH_INFO_RESPONSE, NULL); 201 if (authctxt->kbdintctxt != NULL) { 202 kbdint_free(authctxt->kbdintctxt); 203 authctxt->kbdintctxt = NULL; 204 } 205 } 206 207 /* side effect: sets authctxt->postponed if a reply was sent*/ 208 static int 209 auth2_challenge_start(Authctxt *authctxt) 210 { 211 KbdintAuthctxt *kbdintctxt = authctxt->kbdintctxt; 212 213 debug2("auth2_challenge_start: devices %s", 214 kbdintctxt->devices ? kbdintctxt->devices : "<empty>"); 215 216 if (kbdint_next_device(kbdintctxt) == 0) { 217 auth2_challenge_stop(authctxt); 218 return 0; 219 } 220 debug("auth2_challenge_start: trying authentication method '%s'", 221 kbdintctxt->device->name); 222 223 if ((kbdintctxt->ctxt = kbdintctxt->device->init_ctx(authctxt)) == NULL) { 224 auth2_challenge_stop(authctxt); 225 return 0; 226 } 227 if (send_userauth_info_request(authctxt) == 0) { 228 auth2_challenge_stop(authctxt); 229 return 0; 230 } 231 dispatch_set(SSH2_MSG_USERAUTH_INFO_RESPONSE, 232 &input_userauth_info_response); 233 234 authctxt->postponed = 1; 235 return 0; 236 } 237 238 static int 239 send_userauth_info_request(Authctxt *authctxt) 240 { 241 KbdintAuthctxt *kbdintctxt; 242 char *name, *instr, **prompts; 243 u_int i, *echo_on; 244 245 kbdintctxt = authctxt->kbdintctxt; 246 if (kbdintctxt->device->query(kbdintctxt->ctxt, 247 &name, &instr, &kbdintctxt->nreq, &prompts, &echo_on)) 248 return 0; 249 250 packet_start(SSH2_MSG_USERAUTH_INFO_REQUEST); 251 packet_put_cstring(name); 252 packet_put_cstring(instr); 253 packet_put_cstring(""); /* language not used */ 254 packet_put_int(kbdintctxt->nreq); 255 for (i = 0; i < kbdintctxt->nreq; i++) { 256 packet_put_cstring(prompts[i]); 257 packet_put_char(echo_on[i]); 258 } 259 packet_send(); 260 packet_write_wait(); 261 262 for (i = 0; i < kbdintctxt->nreq; i++) 263 xfree(prompts[i]); 264 xfree(prompts); 265 xfree(echo_on); 266 xfree(name); 267 xfree(instr); 268 return 1; 269 } 270 271 static void 272 input_userauth_info_response(int type, u_int32_t seq, void *ctxt) 273 { 274 Authctxt *authctxt = ctxt; 275 KbdintAuthctxt *kbdintctxt; 276 int authenticated = 0, res, len; 277 u_int i, nresp; 278 char **response = NULL, *method; 279 280 if (authctxt == NULL) 281 fatal("input_userauth_info_response: no authctxt"); 282 kbdintctxt = authctxt->kbdintctxt; 283 if (kbdintctxt == NULL || kbdintctxt->ctxt == NULL) 284 fatal("input_userauth_info_response: no kbdintctxt"); 285 if (kbdintctxt->device == NULL) 286 fatal("input_userauth_info_response: no device"); 287 288 authctxt->postponed = 0; /* reset */ 289 nresp = packet_get_int(); 290 if (nresp != kbdintctxt->nreq) 291 fatal("input_userauth_info_response: wrong number of replies"); 292 if (nresp > 100) 293 fatal("input_userauth_info_response: too many replies"); 294 if (nresp > 0) { 295 response = xmalloc(nresp * sizeof(char *)); 296 for (i = 0; i < nresp; i++) 297 response[i] = packet_get_string(NULL); 298 } 299 packet_check_eom(); 300 301 res = kbdintctxt->device->respond(kbdintctxt->ctxt, nresp, response); 302 303 for (i = 0; i < nresp; i++) { 304 memset(response[i], 'r', strlen(response[i])); 305 xfree(response[i]); 306 } 307 if (response) 308 xfree(response); 309 310 switch (res) { 311 case 0: 312 /* Success! */ 313 authenticated = authctxt->valid ? 1 : 0; 314 break; 315 case 1: 316 /* Authentication needs further interaction */ 317 if (send_userauth_info_request(authctxt) == 1) 318 authctxt->postponed = 1; 319 break; 320 default: 321 /* Failure! */ 322 break; 323 } 324 325 len = strlen("keyboard-interactive") + 2 + 326 strlen(kbdintctxt->device->name); 327 method = xmalloc(len); 328 snprintf(method, len, "keyboard-interactive/%s", 329 kbdintctxt->device->name); 330 331 if (!authctxt->postponed) { 332 if (authenticated) { 333 auth2_challenge_stop(authctxt); 334 } else { 335 /* start next device */ 336 /* may set authctxt->postponed */ 337 auth2_challenge_start(authctxt); 338 } 339 } 340 userauth_finish(authctxt, authenticated, method); 341 xfree(method); 342 } 343 344 void 345 privsep_challenge_enable(void) 346 { 347 #if defined(BSD_AUTH) || defined(USE_PAM) || defined(SKEY) 348 int n = 0; 349 #endif 350 #ifdef BSD_AUTH 351 extern KbdintDevice mm_bsdauth_device; 352 #endif 353 #ifdef USE_PAM 354 extern KbdintDevice mm_sshpam_device; 355 #endif 356 #ifdef SKEY 357 extern KbdintDevice mm_skey_device; 358 #endif 359 360 #ifdef BSD_AUTH 361 devices[n++] = &mm_bsdauth_device; 362 #else 363 #ifdef USE_PAM 364 devices[n++] = &mm_sshpam_device; 365 #endif 366 #ifdef SKEY 367 devices[n++] = &mm_skey_device; 368 #endif 369 #endif 370 } 371