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 28 #include "ssh2.h" 29 #include "auth.h" 30 #include "buffer.h" 31 #include "packet.h" 32 #include "xmalloc.h" 33 #include "dispatch.h" 34 #include "auth.h" 35 #include "log.h" 36 37 static int auth2_challenge_start(Authctxt *); 38 static int send_userauth_info_request(Authctxt *); 39 static void input_userauth_info_response(int, u_int32_t, void *); 40 41 #ifdef BSD_AUTH 42 extern KbdintDevice bsdauth_device; 43 #else 44 #ifdef SKEY 45 extern KbdintDevice skey_device; 46 #endif 47 #endif 48 49 KbdintDevice *devices[] = { 50 #ifdef BSD_AUTH 51 &bsdauth_device, 52 #else 53 #ifdef SKEY 54 &skey_device, 55 #endif 56 #endif 57 NULL 58 }; 59 60 typedef struct KbdintAuthctxt KbdintAuthctxt; 61 struct KbdintAuthctxt 62 { 63 char *devices; 64 void *ctxt; 65 KbdintDevice *device; 66 u_int nreq; 67 }; 68 69 static KbdintAuthctxt * 70 kbdint_alloc(const char *devs) 71 { 72 KbdintAuthctxt *kbdintctxt; 73 Buffer b; 74 int i; 75 76 kbdintctxt = xmalloc(sizeof(KbdintAuthctxt)); 77 if (strcmp(devs, "") == 0) { 78 buffer_init(&b); 79 for (i = 0; devices[i]; i++) { 80 if (buffer_len(&b) > 0) 81 buffer_append(&b, ",", 1); 82 buffer_append(&b, devices[i]->name, 83 strlen(devices[i]->name)); 84 } 85 buffer_append(&b, "\0", 1); 86 kbdintctxt->devices = xstrdup(buffer_ptr(&b)); 87 buffer_free(&b); 88 } else { 89 kbdintctxt->devices = xstrdup(devs); 90 } 91 debug("kbdint_alloc: devices '%s'", kbdintctxt->devices); 92 kbdintctxt->ctxt = NULL; 93 kbdintctxt->device = NULL; 94 kbdintctxt->nreq = 0; 95 96 return kbdintctxt; 97 } 98 static void 99 kbdint_reset_device(KbdintAuthctxt *kbdintctxt) 100 { 101 if (kbdintctxt->ctxt) { 102 kbdintctxt->device->free_ctx(kbdintctxt->ctxt); 103 kbdintctxt->ctxt = NULL; 104 } 105 kbdintctxt->device = NULL; 106 } 107 static void 108 kbdint_free(KbdintAuthctxt *kbdintctxt) 109 { 110 if (kbdintctxt->device) 111 kbdint_reset_device(kbdintctxt); 112 if (kbdintctxt->devices) { 113 xfree(kbdintctxt->devices); 114 kbdintctxt->devices = NULL; 115 } 116 xfree(kbdintctxt); 117 } 118 /* get next device */ 119 static int 120 kbdint_next_device(KbdintAuthctxt *kbdintctxt) 121 { 122 size_t len; 123 char *t; 124 int i; 125 126 if (kbdintctxt->device) 127 kbdint_reset_device(kbdintctxt); 128 do { 129 len = kbdintctxt->devices ? 130 strcspn(kbdintctxt->devices, ",") : 0; 131 132 if (len == 0) 133 break; 134 for (i = 0; devices[i]; i++) 135 if (strncmp(kbdintctxt->devices, devices[i]->name, len) == 0) 136 kbdintctxt->device = devices[i]; 137 t = kbdintctxt->devices; 138 kbdintctxt->devices = t[len] ? xstrdup(t+len+1) : NULL; 139 xfree(t); 140 debug2("kbdint_next_device: devices %s", kbdintctxt->devices ? 141 kbdintctxt->devices : "<empty>"); 142 } while (kbdintctxt->devices && !kbdintctxt->device); 143 144 return kbdintctxt->device ? 1 : 0; 145 } 146 147 /* 148 * try challenge-response, set authctxt->postponed if we have to 149 * wait for the response. 150 */ 151 int 152 auth2_challenge(Authctxt *authctxt, char *devs) 153 { 154 debug("auth2_challenge: user=%s devs=%s", 155 authctxt->user ? authctxt->user : "<nouser>", 156 devs ? devs : "<no devs>"); 157 158 if (authctxt->user == NULL || !devs) 159 return 0; 160 if (authctxt->kbdintctxt == NULL) 161 authctxt->kbdintctxt = kbdint_alloc(devs); 162 return auth2_challenge_start(authctxt); 163 } 164 165 /* unregister kbd-int callbacks and context */ 166 void 167 auth2_challenge_stop(Authctxt *authctxt) 168 { 169 /* unregister callback */ 170 dispatch_set(SSH2_MSG_USERAUTH_INFO_RESPONSE, NULL); 171 if (authctxt->kbdintctxt != NULL) { 172 kbdint_free(authctxt->kbdintctxt); 173 authctxt->kbdintctxt = NULL; 174 } 175 } 176 177 /* side effect: sets authctxt->postponed if a reply was sent*/ 178 static int 179 auth2_challenge_start(Authctxt *authctxt) 180 { 181 KbdintAuthctxt *kbdintctxt = authctxt->kbdintctxt; 182 183 debug2("auth2_challenge_start: devices %s", 184 kbdintctxt->devices ? kbdintctxt->devices : "<empty>"); 185 186 if (kbdint_next_device(kbdintctxt) == 0) { 187 auth2_challenge_stop(authctxt); 188 return 0; 189 } 190 debug("auth2_challenge_start: trying authentication method '%s'", 191 kbdintctxt->device->name); 192 193 if ((kbdintctxt->ctxt = kbdintctxt->device->init_ctx(authctxt)) == NULL) { 194 auth2_challenge_stop(authctxt); 195 return 0; 196 } 197 if (send_userauth_info_request(authctxt) == 0) { 198 auth2_challenge_stop(authctxt); 199 return 0; 200 } 201 dispatch_set(SSH2_MSG_USERAUTH_INFO_RESPONSE, 202 &input_userauth_info_response); 203 204 authctxt->postponed = 1; 205 return 0; 206 } 207 208 static int 209 send_userauth_info_request(Authctxt *authctxt) 210 { 211 KbdintAuthctxt *kbdintctxt; 212 char *name, *instr, **prompts; 213 int i; 214 u_int *echo_on; 215 216 kbdintctxt = authctxt->kbdintctxt; 217 if (kbdintctxt->device->query(kbdintctxt->ctxt, 218 &name, &instr, &kbdintctxt->nreq, &prompts, &echo_on)) 219 return 0; 220 221 packet_start(SSH2_MSG_USERAUTH_INFO_REQUEST); 222 packet_put_cstring(name); 223 packet_put_cstring(instr); 224 packet_put_cstring(""); /* language not used */ 225 packet_put_int(kbdintctxt->nreq); 226 for (i = 0; i < kbdintctxt->nreq; i++) { 227 packet_put_cstring(prompts[i]); 228 packet_put_char(echo_on[i]); 229 } 230 packet_send(); 231 packet_write_wait(); 232 233 for (i = 0; i < kbdintctxt->nreq; i++) 234 xfree(prompts[i]); 235 xfree(prompts); 236 xfree(echo_on); 237 xfree(name); 238 xfree(instr); 239 return 1; 240 } 241 242 static void 243 input_userauth_info_response(int type, u_int32_t seq, void *ctxt) 244 { 245 Authctxt *authctxt = ctxt; 246 KbdintAuthctxt *kbdintctxt; 247 int i, authenticated = 0, res, len; 248 u_int nresp; 249 char **response = NULL, *method; 250 251 if (authctxt == NULL) 252 fatal("input_userauth_info_response: no authctxt"); 253 kbdintctxt = authctxt->kbdintctxt; 254 if (kbdintctxt == NULL || kbdintctxt->ctxt == NULL) 255 fatal("input_userauth_info_response: no kbdintctxt"); 256 if (kbdintctxt->device == NULL) 257 fatal("input_userauth_info_response: no device"); 258 259 authctxt->postponed = 0; /* reset */ 260 nresp = packet_get_int(); 261 if (nresp != kbdintctxt->nreq) 262 fatal("input_userauth_info_response: wrong number of replies"); 263 if (nresp > 100) 264 fatal("input_userauth_info_response: too many replies"); 265 if (nresp > 0) { 266 response = xmalloc(nresp * sizeof(char *)); 267 for (i = 0; i < nresp; i++) 268 response[i] = packet_get_string(NULL); 269 } 270 packet_check_eom(); 271 272 if (authctxt->valid) { 273 res = kbdintctxt->device->respond(kbdintctxt->ctxt, 274 nresp, response); 275 } else { 276 res = -1; 277 } 278 279 for (i = 0; i < nresp; i++) { 280 memset(response[i], 'r', strlen(response[i])); 281 xfree(response[i]); 282 } 283 if (response) 284 xfree(response); 285 286 switch (res) { 287 case 0: 288 /* Success! */ 289 authenticated = 1; 290 break; 291 case 1: 292 /* Authentication needs further interaction */ 293 if (send_userauth_info_request(authctxt) == 1) 294 authctxt->postponed = 1; 295 break; 296 default: 297 /* Failure! */ 298 break; 299 } 300 301 len = strlen("keyboard-interactive") + 2 + 302 strlen(kbdintctxt->device->name); 303 method = xmalloc(len); 304 snprintf(method, len, "keyboard-interactive/%s", 305 kbdintctxt->device->name); 306 307 if (!authctxt->postponed) { 308 if (authenticated) { 309 auth2_challenge_stop(authctxt); 310 } else { 311 /* start next device */ 312 /* may set authctxt->postponed */ 313 auth2_challenge_start(authctxt); 314 } 315 } 316 userauth_finish(authctxt, authenticated, method); 317 xfree(method); 318 } 319 320 void 321 privsep_challenge_enable(void) 322 { 323 #ifdef BSD_AUTH 324 extern KbdintDevice mm_bsdauth_device; 325 #endif 326 #ifdef SKEY 327 extern KbdintDevice mm_skey_device; 328 #endif 329 /* As long as SSHv1 has devices[0] hard coded this is fine */ 330 #ifdef BSD_AUTH 331 devices[0] = &mm_bsdauth_device; 332 #else 333 #ifdef SKEY 334 devices[0] = &mm_skey_device; 335 #endif 336 #endif 337 } 338