1 /* $OpenBSD: auth2-chall.c,v 1.34 2008/12/09 04:32:22 djm 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 extern KbdintDevice bsdauth_device; 47 48 KbdintDevice *devices[] = { 49 &bsdauth_device, 50 NULL 51 }; 52 53 typedef struct KbdintAuthctxt KbdintAuthctxt; 54 struct KbdintAuthctxt 55 { 56 char *devices; 57 void *ctxt; 58 KbdintDevice *device; 59 u_int nreq; 60 }; 61 62 static KbdintAuthctxt * 63 kbdint_alloc(const char *devs) 64 { 65 KbdintAuthctxt *kbdintctxt; 66 Buffer b; 67 int i; 68 69 kbdintctxt = xmalloc(sizeof(KbdintAuthctxt)); 70 if (strcmp(devs, "") == 0) { 71 buffer_init(&b); 72 for (i = 0; devices[i]; i++) { 73 if (buffer_len(&b) > 0) 74 buffer_append(&b, ",", 1); 75 buffer_append(&b, devices[i]->name, 76 strlen(devices[i]->name)); 77 } 78 buffer_append(&b, "\0", 1); 79 kbdintctxt->devices = xstrdup(buffer_ptr(&b)); 80 buffer_free(&b); 81 } else { 82 kbdintctxt->devices = xstrdup(devs); 83 } 84 debug("kbdint_alloc: devices '%s'", kbdintctxt->devices); 85 kbdintctxt->ctxt = NULL; 86 kbdintctxt->device = NULL; 87 kbdintctxt->nreq = 0; 88 89 return kbdintctxt; 90 } 91 static void 92 kbdint_reset_device(KbdintAuthctxt *kbdintctxt) 93 { 94 if (kbdintctxt->ctxt) { 95 kbdintctxt->device->free_ctx(kbdintctxt->ctxt); 96 kbdintctxt->ctxt = NULL; 97 } 98 kbdintctxt->device = NULL; 99 } 100 static void 101 kbdint_free(KbdintAuthctxt *kbdintctxt) 102 { 103 if (kbdintctxt->device) 104 kbdint_reset_device(kbdintctxt); 105 if (kbdintctxt->devices) { 106 xfree(kbdintctxt->devices); 107 kbdintctxt->devices = NULL; 108 } 109 xfree(kbdintctxt); 110 } 111 /* get next device */ 112 static int 113 kbdint_next_device(KbdintAuthctxt *kbdintctxt) 114 { 115 size_t len; 116 char *t; 117 int i; 118 119 if (kbdintctxt->device) 120 kbdint_reset_device(kbdintctxt); 121 do { 122 len = kbdintctxt->devices ? 123 strcspn(kbdintctxt->devices, ",") : 0; 124 125 if (len == 0) 126 break; 127 for (i = 0; devices[i]; i++) 128 if (strncmp(kbdintctxt->devices, devices[i]->name, len) == 0) 129 kbdintctxt->device = devices[i]; 130 t = kbdintctxt->devices; 131 kbdintctxt->devices = t[len] ? xstrdup(t+len+1) : NULL; 132 xfree(t); 133 debug2("kbdint_next_device: devices %s", kbdintctxt->devices ? 134 kbdintctxt->devices : "<empty>"); 135 } while (kbdintctxt->devices && !kbdintctxt->device); 136 137 return kbdintctxt->device ? 1 : 0; 138 } 139 140 /* 141 * try challenge-response, set authctxt->postponed if we have to 142 * wait for the response. 143 */ 144 int 145 auth2_challenge(Authctxt *authctxt, char *devs) 146 { 147 debug("auth2_challenge: user=%s devs=%s", 148 authctxt->user ? authctxt->user : "<nouser>", 149 devs ? devs : "<no devs>"); 150 151 if (authctxt->user == NULL || !devs) 152 return 0; 153 if (authctxt->kbdintctxt == NULL) 154 authctxt->kbdintctxt = kbdint_alloc(devs); 155 return auth2_challenge_start(authctxt); 156 } 157 158 /* unregister kbd-int callbacks and context */ 159 void 160 auth2_challenge_stop(Authctxt *authctxt) 161 { 162 /* unregister callback */ 163 dispatch_set(SSH2_MSG_USERAUTH_INFO_RESPONSE, NULL); 164 if (authctxt->kbdintctxt != NULL) { 165 kbdint_free(authctxt->kbdintctxt); 166 authctxt->kbdintctxt = NULL; 167 } 168 } 169 170 /* side effect: sets authctxt->postponed if a reply was sent*/ 171 static int 172 auth2_challenge_start(Authctxt *authctxt) 173 { 174 KbdintAuthctxt *kbdintctxt = authctxt->kbdintctxt; 175 176 debug2("auth2_challenge_start: devices %s", 177 kbdintctxt->devices ? kbdintctxt->devices : "<empty>"); 178 179 if (kbdint_next_device(kbdintctxt) == 0) { 180 auth2_challenge_stop(authctxt); 181 return 0; 182 } 183 debug("auth2_challenge_start: trying authentication method '%s'", 184 kbdintctxt->device->name); 185 186 if ((kbdintctxt->ctxt = kbdintctxt->device->init_ctx(authctxt)) == NULL) { 187 auth2_challenge_stop(authctxt); 188 return 0; 189 } 190 if (send_userauth_info_request(authctxt) == 0) { 191 auth2_challenge_stop(authctxt); 192 return 0; 193 } 194 dispatch_set(SSH2_MSG_USERAUTH_INFO_RESPONSE, 195 &input_userauth_info_response); 196 197 authctxt->postponed = 1; 198 return 0; 199 } 200 201 static int 202 send_userauth_info_request(Authctxt *authctxt) 203 { 204 KbdintAuthctxt *kbdintctxt; 205 char *name, *instr, **prompts; 206 u_int i, *echo_on; 207 208 kbdintctxt = authctxt->kbdintctxt; 209 if (kbdintctxt->device->query(kbdintctxt->ctxt, 210 &name, &instr, &kbdintctxt->nreq, &prompts, &echo_on)) 211 return 0; 212 213 packet_start(SSH2_MSG_USERAUTH_INFO_REQUEST); 214 packet_put_cstring(name); 215 packet_put_cstring(instr); 216 packet_put_cstring(""); /* language not used */ 217 packet_put_int(kbdintctxt->nreq); 218 for (i = 0; i < kbdintctxt->nreq; i++) { 219 packet_put_cstring(prompts[i]); 220 packet_put_char(echo_on[i]); 221 } 222 packet_send(); 223 packet_write_wait(); 224 225 for (i = 0; i < kbdintctxt->nreq; i++) 226 xfree(prompts[i]); 227 xfree(prompts); 228 xfree(echo_on); 229 xfree(name); 230 xfree(instr); 231 return 1; 232 } 233 234 static void 235 input_userauth_info_response(int type, u_int32_t seq, void *ctxt) 236 { 237 Authctxt *authctxt = ctxt; 238 KbdintAuthctxt *kbdintctxt; 239 int authenticated = 0, res; 240 u_int i, nresp; 241 char **response = NULL, *method; 242 243 if (authctxt == NULL) 244 fatal("input_userauth_info_response: no authctxt"); 245 kbdintctxt = authctxt->kbdintctxt; 246 if (kbdintctxt == NULL || kbdintctxt->ctxt == NULL) 247 fatal("input_userauth_info_response: no kbdintctxt"); 248 if (kbdintctxt->device == NULL) 249 fatal("input_userauth_info_response: no device"); 250 251 authctxt->postponed = 0; /* reset */ 252 nresp = packet_get_int(); 253 if (nresp != kbdintctxt->nreq) 254 fatal("input_userauth_info_response: wrong number of replies"); 255 if (nresp > 100) 256 fatal("input_userauth_info_response: too many replies"); 257 if (nresp > 0) { 258 response = xcalloc(nresp, sizeof(char *)); 259 for (i = 0; i < nresp; i++) 260 response[i] = packet_get_string(NULL); 261 } 262 packet_check_eom(); 263 264 res = kbdintctxt->device->respond(kbdintctxt->ctxt, nresp, response); 265 266 for (i = 0; i < nresp; i++) { 267 memset(response[i], 'r', strlen(response[i])); 268 xfree(response[i]); 269 } 270 if (response) 271 xfree(response); 272 273 switch (res) { 274 case 0: 275 /* Success! */ 276 authenticated = authctxt->valid ? 1 : 0; 277 break; 278 case 1: 279 /* Authentication needs further interaction */ 280 if (send_userauth_info_request(authctxt) == 1) 281 authctxt->postponed = 1; 282 break; 283 default: 284 /* Failure! */ 285 break; 286 } 287 288 xasprintf(&method, "keyboard-interactive/%s", kbdintctxt->device->name); 289 290 if (!authctxt->postponed) { 291 if (authenticated) { 292 auth2_challenge_stop(authctxt); 293 } else { 294 /* start next device */ 295 /* may set authctxt->postponed */ 296 auth2_challenge_start(authctxt); 297 } 298 } 299 userauth_finish(authctxt, authenticated, method); 300 xfree(method); 301 } 302 303 void 304 privsep_challenge_enable(void) 305 { 306 extern KbdintDevice mm_bsdauth_device; 307 /* As long as SSHv1 has devices[0] hard coded this is fine */ 308 devices[0] = &mm_bsdauth_device; 309 } 310