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 1.21 2004/06/01 14:20:45 dtucker 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 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 USE_PAM 45 extern KbdintDevice sshpam_device; 46 #endif 47 #ifdef SKEY 48 extern KbdintDevice skey_device; 49 #endif 50 #endif 51 52 KbdintDevice *devices[] = { 53 #ifdef BSD_AUTH 54 &bsdauth_device, 55 #else 56 #ifdef USE_PAM 57 &sshpam_device, 58 #endif 59 #ifdef SKEY 60 &skey_device, 61 #endif 62 #endif 63 NULL 64 }; 65 66 typedef struct KbdintAuthctxt KbdintAuthctxt; 67 struct KbdintAuthctxt 68 { 69 char *devices; 70 void *ctxt; 71 KbdintDevice *device; 72 u_int nreq; 73 }; 74 75 static KbdintAuthctxt * 76 kbdint_alloc(const char *devs) 77 { 78 KbdintAuthctxt *kbdintctxt; 79 Buffer b; 80 int i; 81 82 kbdintctxt = xmalloc(sizeof(KbdintAuthctxt)); 83 if (strcmp(devs, "") == 0) { 84 buffer_init(&b); 85 for (i = 0; devices[i]; i++) { 86 if (buffer_len(&b) > 0) 87 buffer_append(&b, ",", 1); 88 buffer_append(&b, devices[i]->name, 89 strlen(devices[i]->name)); 90 } 91 buffer_append(&b, "\0", 1); 92 kbdintctxt->devices = xstrdup(buffer_ptr(&b)); 93 buffer_free(&b); 94 } else { 95 kbdintctxt->devices = xstrdup(devs); 96 } 97 debug("kbdint_alloc: devices '%s'", kbdintctxt->devices); 98 kbdintctxt->ctxt = NULL; 99 kbdintctxt->device = NULL; 100 kbdintctxt->nreq = 0; 101 102 return kbdintctxt; 103 } 104 static void 105 kbdint_reset_device(KbdintAuthctxt *kbdintctxt) 106 { 107 if (kbdintctxt->ctxt) { 108 kbdintctxt->device->free_ctx(kbdintctxt->ctxt); 109 kbdintctxt->ctxt = NULL; 110 } 111 kbdintctxt->device = NULL; 112 } 113 static void 114 kbdint_free(KbdintAuthctxt *kbdintctxt) 115 { 116 if (kbdintctxt->device) 117 kbdint_reset_device(kbdintctxt); 118 if (kbdintctxt->devices) { 119 xfree(kbdintctxt->devices); 120 kbdintctxt->devices = NULL; 121 } 122 xfree(kbdintctxt); 123 } 124 /* get next device */ 125 static int 126 kbdint_next_device(KbdintAuthctxt *kbdintctxt) 127 { 128 size_t len; 129 char *t; 130 int i; 131 132 if (kbdintctxt->device) 133 kbdint_reset_device(kbdintctxt); 134 do { 135 len = kbdintctxt->devices ? 136 strcspn(kbdintctxt->devices, ",") : 0; 137 138 if (len == 0) 139 break; 140 for (i = 0; devices[i]; i++) 141 if (strncmp(kbdintctxt->devices, devices[i]->name, len) == 0) 142 kbdintctxt->device = devices[i]; 143 t = kbdintctxt->devices; 144 kbdintctxt->devices = t[len] ? xstrdup(t+len+1) : NULL; 145 xfree(t); 146 debug2("kbdint_next_device: devices %s", kbdintctxt->devices ? 147 kbdintctxt->devices : "<empty>"); 148 } while (kbdintctxt->devices && !kbdintctxt->device); 149 150 return kbdintctxt->device ? 1 : 0; 151 } 152 153 /* 154 * try challenge-response, set authctxt->postponed if we have to 155 * wait for the response. 156 */ 157 int 158 auth2_challenge(Authctxt *authctxt, char *devs) 159 { 160 debug("auth2_challenge: user=%s devs=%s", 161 authctxt->user ? authctxt->user : "<nouser>", 162 devs ? devs : "<no devs>"); 163 164 if (authctxt->user == NULL || !devs) 165 return 0; 166 if (authctxt->kbdintctxt == NULL) 167 authctxt->kbdintctxt = kbdint_alloc(devs); 168 return auth2_challenge_start(authctxt); 169 } 170 171 /* unregister kbd-int callbacks and context */ 172 void 173 auth2_challenge_stop(Authctxt *authctxt) 174 { 175 /* unregister callback */ 176 dispatch_set(SSH2_MSG_USERAUTH_INFO_RESPONSE, NULL); 177 if (authctxt->kbdintctxt != NULL) { 178 kbdint_free(authctxt->kbdintctxt); 179 authctxt->kbdintctxt = NULL; 180 } 181 } 182 183 /* side effect: sets authctxt->postponed if a reply was sent*/ 184 static int 185 auth2_challenge_start(Authctxt *authctxt) 186 { 187 KbdintAuthctxt *kbdintctxt = authctxt->kbdintctxt; 188 189 debug2("auth2_challenge_start: devices %s", 190 kbdintctxt->devices ? kbdintctxt->devices : "<empty>"); 191 192 if (kbdint_next_device(kbdintctxt) == 0) { 193 auth2_challenge_stop(authctxt); 194 return 0; 195 } 196 debug("auth2_challenge_start: trying authentication method '%s'", 197 kbdintctxt->device->name); 198 199 if ((kbdintctxt->ctxt = kbdintctxt->device->init_ctx(authctxt)) == NULL) { 200 auth2_challenge_stop(authctxt); 201 return 0; 202 } 203 if (send_userauth_info_request(authctxt) == 0) { 204 auth2_challenge_stop(authctxt); 205 return 0; 206 } 207 dispatch_set(SSH2_MSG_USERAUTH_INFO_RESPONSE, 208 &input_userauth_info_response); 209 210 authctxt->postponed = 1; 211 return 0; 212 } 213 214 static int 215 send_userauth_info_request(Authctxt *authctxt) 216 { 217 KbdintAuthctxt *kbdintctxt; 218 char *name, *instr, **prompts; 219 int i; 220 u_int *echo_on; 221 222 kbdintctxt = authctxt->kbdintctxt; 223 if (kbdintctxt->device->query(kbdintctxt->ctxt, 224 &name, &instr, &kbdintctxt->nreq, &prompts, &echo_on)) 225 return 0; 226 227 packet_start(SSH2_MSG_USERAUTH_INFO_REQUEST); 228 packet_put_cstring(name); 229 packet_put_cstring(instr); 230 packet_put_cstring(""); /* language not used */ 231 packet_put_int(kbdintctxt->nreq); 232 for (i = 0; i < kbdintctxt->nreq; i++) { 233 packet_put_cstring(prompts[i]); 234 packet_put_char(echo_on[i]); 235 } 236 packet_send(); 237 packet_write_wait(); 238 239 for (i = 0; i < kbdintctxt->nreq; i++) 240 xfree(prompts[i]); 241 xfree(prompts); 242 xfree(echo_on); 243 xfree(name); 244 xfree(instr); 245 return 1; 246 } 247 248 static void 249 input_userauth_info_response(int type, u_int32_t seq, void *ctxt) 250 { 251 Authctxt *authctxt = ctxt; 252 KbdintAuthctxt *kbdintctxt; 253 int i, authenticated = 0, res, len; 254 u_int nresp; 255 char **response = NULL, *method; 256 257 if (authctxt == NULL) 258 fatal("input_userauth_info_response: no authctxt"); 259 kbdintctxt = authctxt->kbdintctxt; 260 if (kbdintctxt == NULL || kbdintctxt->ctxt == NULL) 261 fatal("input_userauth_info_response: no kbdintctxt"); 262 if (kbdintctxt->device == NULL) 263 fatal("input_userauth_info_response: no device"); 264 265 authctxt->postponed = 0; /* reset */ 266 nresp = packet_get_int(); 267 if (nresp != kbdintctxt->nreq) 268 fatal("input_userauth_info_response: wrong number of replies"); 269 if (nresp > 100) 270 fatal("input_userauth_info_response: too many replies"); 271 if (nresp > 0) { 272 response = xmalloc(nresp * sizeof(char *)); 273 for (i = 0; i < nresp; i++) 274 response[i] = packet_get_string(NULL); 275 } 276 packet_check_eom(); 277 278 if (authctxt->valid) { 279 res = kbdintctxt->device->respond(kbdintctxt->ctxt, 280 nresp, response); 281 } else { 282 res = -1; 283 } 284 285 for (i = 0; i < nresp; i++) { 286 memset(response[i], 'r', strlen(response[i])); 287 xfree(response[i]); 288 } 289 if (response) 290 xfree(response); 291 292 switch (res) { 293 case 0: 294 /* Success! */ 295 authenticated = 1; 296 break; 297 case 1: 298 /* Authentication needs further interaction */ 299 if (send_userauth_info_request(authctxt) == 1) 300 authctxt->postponed = 1; 301 break; 302 default: 303 /* Failure! */ 304 break; 305 } 306 307 len = strlen("keyboard-interactive") + 2 + 308 strlen(kbdintctxt->device->name); 309 method = xmalloc(len); 310 snprintf(method, len, "keyboard-interactive/%s", 311 kbdintctxt->device->name); 312 313 if (!authctxt->postponed) { 314 if (authenticated) { 315 auth2_challenge_stop(authctxt); 316 } else { 317 /* start next device */ 318 /* may set authctxt->postponed */ 319 auth2_challenge_start(authctxt); 320 } 321 } 322 userauth_finish(authctxt, authenticated, method); 323 xfree(method); 324 } 325 326 void 327 privsep_challenge_enable(void) 328 { 329 #if defined(BSD_AUTH) || defined(USE_PAM) || defined(SKEY) 330 int n = 0; 331 #endif 332 #ifdef BSD_AUTH 333 extern KbdintDevice mm_bsdauth_device; 334 #endif 335 #ifdef USE_PAM 336 extern KbdintDevice mm_sshpam_device; 337 #endif 338 #ifdef SKEY 339 extern KbdintDevice mm_skey_device; 340 #endif 341 342 #ifdef BSD_AUTH 343 devices[n++] = &mm_bsdauth_device; 344 #else 345 #ifdef USE_PAM 346 devices[n++] = &mm_sshpam_device; 347 #endif 348 #ifdef SKEY 349 devices[n++] = &mm_skey_device; 350 #endif 351 #endif 352 } 353