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 1.20 2002/06/30 21:59:45 deraadt 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 "auth.h" 36 #include "log.h" 37 38 static int auth2_challenge_start(Authctxt *); 39 static int send_userauth_info_request(Authctxt *); 40 static void input_userauth_info_response(int, u_int32_t, void *); 41 42 #ifdef BSD_AUTH 43 extern KbdintDevice bsdauth_device; 44 #else 45 #ifdef USE_PAM 46 extern KbdintDevice sshpam_device; 47 #endif 48 #ifdef SKEY 49 extern KbdintDevice skey_device; 50 #endif 51 #endif 52 53 KbdintDevice *devices[] = { 54 #ifdef BSD_AUTH 55 &bsdauth_device, 56 #else 57 #ifdef USE_PAM 58 &sshpam_device, 59 #endif 60 #ifdef SKEY 61 &skey_device, 62 #endif 63 #endif 64 NULL 65 }; 66 67 typedef struct KbdintAuthctxt KbdintAuthctxt; 68 struct KbdintAuthctxt 69 { 70 char *devices; 71 void *ctxt; 72 KbdintDevice *device; 73 u_int nreq; 74 }; 75 76 static KbdintAuthctxt * 77 kbdint_alloc(const char *devs) 78 { 79 KbdintAuthctxt *kbdintctxt; 80 Buffer b; 81 int i; 82 83 kbdintctxt = xmalloc(sizeof(KbdintAuthctxt)); 84 if (strcmp(devs, "") == 0) { 85 buffer_init(&b); 86 for (i = 0; devices[i]; i++) { 87 if (buffer_len(&b) > 0) 88 buffer_append(&b, ",", 1); 89 buffer_append(&b, devices[i]->name, 90 strlen(devices[i]->name)); 91 } 92 buffer_append(&b, "\0", 1); 93 kbdintctxt->devices = xstrdup(buffer_ptr(&b)); 94 buffer_free(&b); 95 } else { 96 kbdintctxt->devices = xstrdup(devs); 97 } 98 debug("kbdint_alloc: devices '%s'", kbdintctxt->devices); 99 kbdintctxt->ctxt = NULL; 100 kbdintctxt->device = NULL; 101 kbdintctxt->nreq = 0; 102 103 return kbdintctxt; 104 } 105 static void 106 kbdint_reset_device(KbdintAuthctxt *kbdintctxt) 107 { 108 if (kbdintctxt->ctxt) { 109 kbdintctxt->device->free_ctx(kbdintctxt->ctxt); 110 kbdintctxt->ctxt = NULL; 111 } 112 kbdintctxt->device = NULL; 113 } 114 static void 115 kbdint_free(KbdintAuthctxt *kbdintctxt) 116 { 117 if (kbdintctxt->device) 118 kbdint_reset_device(kbdintctxt); 119 if (kbdintctxt->devices) { 120 xfree(kbdintctxt->devices); 121 kbdintctxt->devices = NULL; 122 } 123 xfree(kbdintctxt); 124 } 125 /* get next device */ 126 static int 127 kbdint_next_device(KbdintAuthctxt *kbdintctxt) 128 { 129 size_t len; 130 char *t; 131 int i; 132 133 if (kbdintctxt->device) 134 kbdint_reset_device(kbdintctxt); 135 do { 136 len = kbdintctxt->devices ? 137 strcspn(kbdintctxt->devices, ",") : 0; 138 139 if (len == 0) 140 break; 141 for (i = 0; devices[i]; i++) 142 if (strncmp(kbdintctxt->devices, devices[i]->name, len) == 0) 143 kbdintctxt->device = devices[i]; 144 t = kbdintctxt->devices; 145 kbdintctxt->devices = t[len] ? xstrdup(t+len+1) : NULL; 146 xfree(t); 147 debug2("kbdint_next_device: devices %s", kbdintctxt->devices ? 148 kbdintctxt->devices : "<empty>"); 149 } while (kbdintctxt->devices && !kbdintctxt->device); 150 151 return kbdintctxt->device ? 1 : 0; 152 } 153 154 /* 155 * try challenge-response, set authctxt->postponed if we have to 156 * wait for the response. 157 */ 158 int 159 auth2_challenge(Authctxt *authctxt, char *devs) 160 { 161 debug("auth2_challenge: user=%s devs=%s", 162 authctxt->user ? authctxt->user : "<nouser>", 163 devs ? devs : "<no devs>"); 164 165 if (authctxt->user == NULL || !devs) 166 return 0; 167 if (authctxt->kbdintctxt == NULL) 168 authctxt->kbdintctxt = kbdint_alloc(devs); 169 return auth2_challenge_start(authctxt); 170 } 171 172 /* unregister kbd-int callbacks and context */ 173 void 174 auth2_challenge_stop(Authctxt *authctxt) 175 { 176 /* unregister callback */ 177 dispatch_set(SSH2_MSG_USERAUTH_INFO_RESPONSE, NULL); 178 if (authctxt->kbdintctxt != NULL) { 179 kbdint_free(authctxt->kbdintctxt); 180 authctxt->kbdintctxt = NULL; 181 } 182 } 183 184 /* side effect: sets authctxt->postponed if a reply was sent*/ 185 static int 186 auth2_challenge_start(Authctxt *authctxt) 187 { 188 KbdintAuthctxt *kbdintctxt = authctxt->kbdintctxt; 189 190 debug2("auth2_challenge_start: devices %s", 191 kbdintctxt->devices ? kbdintctxt->devices : "<empty>"); 192 193 if (kbdint_next_device(kbdintctxt) == 0) { 194 auth2_challenge_stop(authctxt); 195 return 0; 196 } 197 debug("auth2_challenge_start: trying authentication method '%s'", 198 kbdintctxt->device->name); 199 200 if ((kbdintctxt->ctxt = kbdintctxt->device->init_ctx(authctxt)) == NULL) { 201 auth2_challenge_stop(authctxt); 202 return 0; 203 } 204 if (send_userauth_info_request(authctxt) == 0) { 205 auth2_challenge_stop(authctxt); 206 return 0; 207 } 208 dispatch_set(SSH2_MSG_USERAUTH_INFO_RESPONSE, 209 &input_userauth_info_response); 210 211 authctxt->postponed = 1; 212 return 0; 213 } 214 215 static int 216 send_userauth_info_request(Authctxt *authctxt) 217 { 218 KbdintAuthctxt *kbdintctxt; 219 char *name, *instr, **prompts; 220 int i; 221 u_int *echo_on; 222 223 kbdintctxt = authctxt->kbdintctxt; 224 if (kbdintctxt->device->query(kbdintctxt->ctxt, 225 &name, &instr, &kbdintctxt->nreq, &prompts, &echo_on)) 226 return 0; 227 228 packet_start(SSH2_MSG_USERAUTH_INFO_REQUEST); 229 packet_put_cstring(name); 230 packet_put_cstring(instr); 231 packet_put_cstring(""); /* language not used */ 232 packet_put_int(kbdintctxt->nreq); 233 for (i = 0; i < kbdintctxt->nreq; i++) { 234 packet_put_cstring(prompts[i]); 235 packet_put_char(echo_on[i]); 236 } 237 packet_send(); 238 packet_write_wait(); 239 240 for (i = 0; i < kbdintctxt->nreq; i++) 241 xfree(prompts[i]); 242 xfree(prompts); 243 xfree(echo_on); 244 xfree(name); 245 xfree(instr); 246 return 1; 247 } 248 249 static void 250 input_userauth_info_response(int type, u_int32_t seq, void *ctxt) 251 { 252 Authctxt *authctxt = ctxt; 253 KbdintAuthctxt *kbdintctxt; 254 int i, authenticated = 0, res, len; 255 u_int nresp; 256 char **response = NULL, *method; 257 258 if (authctxt == NULL) 259 fatal("input_userauth_info_response: no authctxt"); 260 kbdintctxt = authctxt->kbdintctxt; 261 if (kbdintctxt == NULL || kbdintctxt->ctxt == NULL) 262 fatal("input_userauth_info_response: no kbdintctxt"); 263 if (kbdintctxt->device == NULL) 264 fatal("input_userauth_info_response: no device"); 265 266 authctxt->postponed = 0; /* reset */ 267 nresp = packet_get_int(); 268 if (nresp != kbdintctxt->nreq) 269 fatal("input_userauth_info_response: wrong number of replies"); 270 if (nresp > 100) 271 fatal("input_userauth_info_response: too many replies"); 272 if (nresp > 0) { 273 response = xmalloc(nresp * sizeof(char *)); 274 for (i = 0; i < nresp; i++) 275 response[i] = packet_get_string(NULL); 276 } 277 packet_check_eom(); 278 279 if (authctxt->valid) { 280 res = kbdintctxt->device->respond(kbdintctxt->ctxt, 281 nresp, response); 282 } else { 283 res = -1; 284 } 285 286 for (i = 0; i < nresp; i++) { 287 memset(response[i], 'r', strlen(response[i])); 288 xfree(response[i]); 289 } 290 if (response) 291 xfree(response); 292 293 switch (res) { 294 case 0: 295 /* Success! */ 296 authenticated = 1; 297 break; 298 case 1: 299 /* Authentication needs further interaction */ 300 if (send_userauth_info_request(authctxt) == 1) 301 authctxt->postponed = 1; 302 break; 303 default: 304 /* Failure! */ 305 break; 306 } 307 308 len = strlen("keyboard-interactive") + 2 + 309 strlen(kbdintctxt->device->name); 310 method = xmalloc(len); 311 snprintf(method, len, "keyboard-interactive/%s", 312 kbdintctxt->device->name); 313 314 if (!authctxt->postponed) { 315 if (authenticated) { 316 auth2_challenge_stop(authctxt); 317 } else { 318 /* start next device */ 319 /* may set authctxt->postponed */ 320 auth2_challenge_start(authctxt); 321 } 322 } 323 userauth_finish(authctxt, authenticated, method); 324 xfree(method); 325 } 326 327 void 328 privsep_challenge_enable(void) 329 { 330 #if defined(BSD_AUTH) || defined(USE_PAM) || defined(SKEY) 331 int n = 0; 332 #endif 333 #ifdef BSD_AUTH 334 extern KbdintDevice mm_bsdauth_device; 335 #endif 336 #ifdef USE_PAM 337 extern KbdintDevice mm_sshpam_device; 338 #endif 339 #ifdef SKEY 340 extern KbdintDevice mm_skey_device; 341 #endif 342 343 #ifdef BSD_AUTH 344 devices[n++] = &mm_bsdauth_device; 345 #else 346 #ifdef USE_PAM 347 devices[n++] = &mm_sshpam_device; 348 #endif 349 #ifdef SKEY 350 devices[n++] = &mm_skey_device; 351 #endif 352 #endif 353 } 354