1 /* $OpenBSD: auth2-chall.c,v 1.32 2007/01/03 03:01:40 stevesk Exp $ */ 2 /* 3 * Copyright (c) 2001 Markus Friedl. All rights reserved. 4 * Copyright (c) 2001 Per Allansson. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 */ 26 27 #include <sys/types.h> 28 29 #include <stdio.h> 30 #include <string.h> 31 32 #include "xmalloc.h" 33 #include "ssh2.h" 34 #include "key.h" 35 #include "hostfile.h" 36 #include "auth.h" 37 #include "buffer.h" 38 #include "packet.h" 39 #include "dispatch.h" 40 #include "log.h" 41 42 static int auth2_challenge_start(Authctxt *); 43 static int send_userauth_info_request(Authctxt *); 44 static void input_userauth_info_response(int, u_int32_t, void *); 45 46 #ifdef BSD_AUTH 47 extern KbdintDevice bsdauth_device; 48 #else 49 #ifdef SKEY 50 extern KbdintDevice skey_device; 51 #endif 52 #endif 53 54 KbdintDevice *devices[] = { 55 #ifdef BSD_AUTH 56 &bsdauth_device, 57 #else 58 #ifdef SKEY 59 &skey_device, 60 #endif 61 #endif 62 NULL 63 }; 64 65 typedef struct KbdintAuthctxt KbdintAuthctxt; 66 struct KbdintAuthctxt 67 { 68 char *devices; 69 void *ctxt; 70 KbdintDevice *device; 71 u_int nreq; 72 }; 73 74 static KbdintAuthctxt * 75 kbdint_alloc(const char *devs) 76 { 77 KbdintAuthctxt *kbdintctxt; 78 Buffer b; 79 int i; 80 81 kbdintctxt = xmalloc(sizeof(KbdintAuthctxt)); 82 if (strcmp(devs, "") == 0) { 83 buffer_init(&b); 84 for (i = 0; devices[i]; i++) { 85 if (buffer_len(&b) > 0) 86 buffer_append(&b, ",", 1); 87 buffer_append(&b, devices[i]->name, 88 strlen(devices[i]->name)); 89 } 90 buffer_append(&b, "\0", 1); 91 kbdintctxt->devices = xstrdup(buffer_ptr(&b)); 92 buffer_free(&b); 93 } else { 94 kbdintctxt->devices = xstrdup(devs); 95 } 96 debug("kbdint_alloc: devices '%s'", kbdintctxt->devices); 97 kbdintctxt->ctxt = NULL; 98 kbdintctxt->device = NULL; 99 kbdintctxt->nreq = 0; 100 101 return kbdintctxt; 102 } 103 static void 104 kbdint_reset_device(KbdintAuthctxt *kbdintctxt) 105 { 106 if (kbdintctxt->ctxt) { 107 kbdintctxt->device->free_ctx(kbdintctxt->ctxt); 108 kbdintctxt->ctxt = NULL; 109 } 110 kbdintctxt->device = NULL; 111 } 112 static void 113 kbdint_free(KbdintAuthctxt *kbdintctxt) 114 { 115 if (kbdintctxt->device) 116 kbdint_reset_device(kbdintctxt); 117 if (kbdintctxt->devices) { 118 xfree(kbdintctxt->devices); 119 kbdintctxt->devices = NULL; 120 } 121 xfree(kbdintctxt); 122 } 123 /* get next device */ 124 static int 125 kbdint_next_device(KbdintAuthctxt *kbdintctxt) 126 { 127 size_t len; 128 char *t; 129 int i; 130 131 if (kbdintctxt->device) 132 kbdint_reset_device(kbdintctxt); 133 do { 134 len = kbdintctxt->devices ? 135 strcspn(kbdintctxt->devices, ",") : 0; 136 137 if (len == 0) 138 break; 139 for (i = 0; devices[i]; i++) 140 if (strncmp(kbdintctxt->devices, devices[i]->name, len) == 0) 141 kbdintctxt->device = devices[i]; 142 t = kbdintctxt->devices; 143 kbdintctxt->devices = t[len] ? xstrdup(t+len+1) : NULL; 144 xfree(t); 145 debug2("kbdint_next_device: devices %s", kbdintctxt->devices ? 146 kbdintctxt->devices : "<empty>"); 147 } while (kbdintctxt->devices && !kbdintctxt->device); 148 149 return kbdintctxt->device ? 1 : 0; 150 } 151 152 /* 153 * try challenge-response, set authctxt->postponed if we have to 154 * wait for the response. 155 */ 156 int 157 auth2_challenge(Authctxt *authctxt, char *devs) 158 { 159 debug("auth2_challenge: user=%s devs=%s", 160 authctxt->user ? authctxt->user : "<nouser>", 161 devs ? devs : "<no devs>"); 162 163 if (authctxt->user == NULL || !devs) 164 return 0; 165 if (authctxt->kbdintctxt == NULL) 166 authctxt->kbdintctxt = kbdint_alloc(devs); 167 return auth2_challenge_start(authctxt); 168 } 169 170 /* unregister kbd-int callbacks and context */ 171 void 172 auth2_challenge_stop(Authctxt *authctxt) 173 { 174 /* unregister callback */ 175 dispatch_set(SSH2_MSG_USERAUTH_INFO_RESPONSE, NULL); 176 if (authctxt->kbdintctxt != NULL) { 177 kbdint_free(authctxt->kbdintctxt); 178 authctxt->kbdintctxt = NULL; 179 } 180 } 181 182 /* side effect: sets authctxt->postponed if a reply was sent*/ 183 static int 184 auth2_challenge_start(Authctxt *authctxt) 185 { 186 KbdintAuthctxt *kbdintctxt = authctxt->kbdintctxt; 187 188 debug2("auth2_challenge_start: devices %s", 189 kbdintctxt->devices ? kbdintctxt->devices : "<empty>"); 190 191 if (kbdint_next_device(kbdintctxt) == 0) { 192 auth2_challenge_stop(authctxt); 193 return 0; 194 } 195 debug("auth2_challenge_start: trying authentication method '%s'", 196 kbdintctxt->device->name); 197 198 if ((kbdintctxt->ctxt = kbdintctxt->device->init_ctx(authctxt)) == NULL) { 199 auth2_challenge_stop(authctxt); 200 return 0; 201 } 202 if (send_userauth_info_request(authctxt) == 0) { 203 auth2_challenge_stop(authctxt); 204 return 0; 205 } 206 dispatch_set(SSH2_MSG_USERAUTH_INFO_RESPONSE, 207 &input_userauth_info_response); 208 209 authctxt->postponed = 1; 210 return 0; 211 } 212 213 static int 214 send_userauth_info_request(Authctxt *authctxt) 215 { 216 KbdintAuthctxt *kbdintctxt; 217 char *name, *instr, **prompts; 218 u_int i, *echo_on; 219 220 kbdintctxt = authctxt->kbdintctxt; 221 if (kbdintctxt->device->query(kbdintctxt->ctxt, 222 &name, &instr, &kbdintctxt->nreq, &prompts, &echo_on)) 223 return 0; 224 225 packet_start(SSH2_MSG_USERAUTH_INFO_REQUEST); 226 packet_put_cstring(name); 227 packet_put_cstring(instr); 228 packet_put_cstring(""); /* language not used */ 229 packet_put_int(kbdintctxt->nreq); 230 for (i = 0; i < kbdintctxt->nreq; i++) { 231 packet_put_cstring(prompts[i]); 232 packet_put_char(echo_on[i]); 233 } 234 packet_send(); 235 packet_write_wait(); 236 237 for (i = 0; i < kbdintctxt->nreq; i++) 238 xfree(prompts[i]); 239 xfree(prompts); 240 xfree(echo_on); 241 xfree(name); 242 xfree(instr); 243 return 1; 244 } 245 246 static void 247 input_userauth_info_response(int type, u_int32_t seq, void *ctxt) 248 { 249 Authctxt *authctxt = ctxt; 250 KbdintAuthctxt *kbdintctxt; 251 int authenticated = 0, res, len; 252 u_int i, nresp; 253 char **response = NULL, *method; 254 255 if (authctxt == NULL) 256 fatal("input_userauth_info_response: no authctxt"); 257 kbdintctxt = authctxt->kbdintctxt; 258 if (kbdintctxt == NULL || kbdintctxt->ctxt == NULL) 259 fatal("input_userauth_info_response: no kbdintctxt"); 260 if (kbdintctxt->device == NULL) 261 fatal("input_userauth_info_response: no device"); 262 263 authctxt->postponed = 0; /* reset */ 264 nresp = packet_get_int(); 265 if (nresp != kbdintctxt->nreq) 266 fatal("input_userauth_info_response: wrong number of replies"); 267 if (nresp > 100) 268 fatal("input_userauth_info_response: too many replies"); 269 if (nresp > 0) { 270 response = xcalloc(nresp, sizeof(char *)); 271 for (i = 0; i < nresp; i++) 272 response[i] = packet_get_string(NULL); 273 } 274 packet_check_eom(); 275 276 res = kbdintctxt->device->respond(kbdintctxt->ctxt, nresp, response); 277 278 for (i = 0; i < nresp; i++) { 279 memset(response[i], 'r', strlen(response[i])); 280 xfree(response[i]); 281 } 282 if (response) 283 xfree(response); 284 285 switch (res) { 286 case 0: 287 /* Success! */ 288 authenticated = authctxt->valid ? 1 : 0; 289 break; 290 case 1: 291 /* Authentication needs further interaction */ 292 if (send_userauth_info_request(authctxt) == 1) 293 authctxt->postponed = 1; 294 break; 295 default: 296 /* Failure! */ 297 break; 298 } 299 300 len = strlen("keyboard-interactive") + 2 + 301 strlen(kbdintctxt->device->name); 302 method = xmalloc(len); 303 snprintf(method, len, "keyboard-interactive/%s", 304 kbdintctxt->device->name); 305 306 if (!authctxt->postponed) { 307 if (authenticated) { 308 auth2_challenge_stop(authctxt); 309 } else { 310 /* start next device */ 311 /* may set authctxt->postponed */ 312 auth2_challenge_start(authctxt); 313 } 314 } 315 userauth_finish(authctxt, authenticated, method); 316 xfree(method); 317 } 318 319 void 320 privsep_challenge_enable(void) 321 { 322 #ifdef BSD_AUTH 323 extern KbdintDevice mm_bsdauth_device; 324 #else 325 #ifdef SKEY 326 extern KbdintDevice mm_skey_device; 327 #endif 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