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 1.13 2001/12/28 15:06:00 markus Exp $"); 27 28 #include "ssh2.h" 29 #include "auth.h" 30 #include "packet.h" 31 #include "xmalloc.h" 32 #include "dispatch.h" 33 #include "auth.h" 34 #include "log.h" 35 36 static int auth2_challenge_start(Authctxt *); 37 static int send_userauth_info_request(Authctxt *); 38 static void input_userauth_info_response(int, u_int32_t, void *); 39 40 #ifdef BSD_AUTH 41 extern KbdintDevice bsdauth_device; 42 #else 43 #ifdef SKEY 44 extern KbdintDevice skey_device; 45 #endif 46 #endif 47 48 KbdintDevice *devices[] = { 49 #ifdef BSD_AUTH 50 &bsdauth_device, 51 #else 52 #ifdef SKEY 53 &skey_device, 54 #endif 55 #endif 56 NULL 57 }; 58 59 typedef struct KbdintAuthctxt KbdintAuthctxt; 60 struct KbdintAuthctxt 61 { 62 char *devices; 63 void *ctxt; 64 KbdintDevice *device; 65 }; 66 67 static KbdintAuthctxt * 68 kbdint_alloc(const char *devs) 69 { 70 KbdintAuthctxt *kbdintctxt; 71 int i; 72 char buf[1024]; 73 74 kbdintctxt = xmalloc(sizeof(KbdintAuthctxt)); 75 if (strcmp(devs, "") == 0) { 76 buf[0] = '\0'; 77 for (i = 0; devices[i]; i++) { 78 if (i != 0) 79 strlcat(buf, ",", sizeof(buf)); 80 strlcat(buf, devices[i]->name, sizeof(buf)); 81 } 82 debug("kbdint_alloc: devices '%s'", buf); 83 kbdintctxt->devices = xstrdup(buf); 84 } else { 85 kbdintctxt->devices = xstrdup(devs); 86 } 87 kbdintctxt->ctxt = NULL; 88 kbdintctxt->device = NULL; 89 90 return kbdintctxt; 91 } 92 static void 93 kbdint_reset_device(KbdintAuthctxt *kbdintctxt) 94 { 95 if (kbdintctxt->ctxt) { 96 kbdintctxt->device->free_ctx(kbdintctxt->ctxt); 97 kbdintctxt->ctxt = NULL; 98 } 99 kbdintctxt->device = NULL; 100 } 101 static void 102 kbdint_free(KbdintAuthctxt *kbdintctxt) 103 { 104 if (kbdintctxt->device) 105 kbdint_reset_device(kbdintctxt); 106 if (kbdintctxt->devices) { 107 xfree(kbdintctxt->devices); 108 kbdintctxt->devices = NULL; 109 } 110 xfree(kbdintctxt); 111 } 112 /* get next device */ 113 static int 114 kbdint_next_device(KbdintAuthctxt *kbdintctxt) 115 { 116 size_t len; 117 char *t; 118 int i; 119 120 if (kbdintctxt->device) 121 kbdint_reset_device(kbdintctxt); 122 do { 123 len = kbdintctxt->devices ? 124 strcspn(kbdintctxt->devices, ",") : 0; 125 126 if (len == 0) 127 break; 128 for (i = 0; devices[i]; i++) 129 if (strncmp(kbdintctxt->devices, devices[i]->name, len) == 0) 130 kbdintctxt->device = devices[i]; 131 t = kbdintctxt->devices; 132 kbdintctxt->devices = t[len] ? xstrdup(t+len+1) : NULL; 133 xfree(t); 134 debug2("kbdint_next_device: devices %s", kbdintctxt->devices ? 135 kbdintctxt->devices : "<empty>"); 136 } while (kbdintctxt->devices && !kbdintctxt->device); 137 138 return kbdintctxt->device ? 1 : 0; 139 } 140 141 /* 142 * try challenge-response, set authctxt->postponed if we have to 143 * wait for the response. 144 */ 145 int 146 auth2_challenge(Authctxt *authctxt, char *devs) 147 { 148 debug("auth2_challenge: user=%s devs=%s", 149 authctxt->user ? authctxt->user : "<nouser>", 150 devs ? devs : "<no devs>"); 151 152 if (authctxt->user == NULL || !devs) 153 return 0; 154 if (authctxt->kbdintctxt == NULL) 155 authctxt->kbdintctxt = kbdint_alloc(devs); 156 return auth2_challenge_start(authctxt); 157 } 158 159 /* unregister kbd-int callbacks and context */ 160 void 161 auth2_challenge_stop(Authctxt *authctxt) 162 { 163 /* unregister callback */ 164 dispatch_set(SSH2_MSG_USERAUTH_INFO_RESPONSE, NULL); 165 if (authctxt->kbdintctxt != NULL) { 166 kbdint_free(authctxt->kbdintctxt); 167 authctxt->kbdintctxt = NULL; 168 } 169 } 170 171 /* side effect: sets authctxt->postponed if a reply was sent*/ 172 static int 173 auth2_challenge_start(Authctxt *authctxt) 174 { 175 KbdintAuthctxt *kbdintctxt = authctxt->kbdintctxt; 176 177 debug2("auth2_challenge_start: devices %s", 178 kbdintctxt->devices ? kbdintctxt->devices : "<empty>"); 179 180 if (kbdint_next_device(kbdintctxt) == 0) { 181 auth2_challenge_stop(authctxt); 182 return 0; 183 } 184 debug("auth2_challenge_start: trying authentication method '%s'", 185 kbdintctxt->device->name); 186 187 if ((kbdintctxt->ctxt = kbdintctxt->device->init_ctx(authctxt)) == NULL) { 188 auth2_challenge_stop(authctxt); 189 return 0; 190 } 191 if (send_userauth_info_request(authctxt) == 0) { 192 auth2_challenge_stop(authctxt); 193 return 0; 194 } 195 dispatch_set(SSH2_MSG_USERAUTH_INFO_RESPONSE, 196 &input_userauth_info_response); 197 198 authctxt->postponed = 1; 199 return 0; 200 } 201 202 static int 203 send_userauth_info_request(Authctxt *authctxt) 204 { 205 KbdintAuthctxt *kbdintctxt; 206 char *name, *instr, **prompts; 207 int i; 208 u_int numprompts, *echo_on; 209 210 kbdintctxt = authctxt->kbdintctxt; 211 if (kbdintctxt->device->query(kbdintctxt->ctxt, 212 &name, &instr, &numprompts, &prompts, &echo_on)) 213 return 0; 214 215 packet_start(SSH2_MSG_USERAUTH_INFO_REQUEST); 216 packet_put_cstring(name); 217 packet_put_cstring(instr); 218 packet_put_cstring(""); /* language not used */ 219 packet_put_int(numprompts); 220 for (i = 0; i < numprompts; i++) { 221 packet_put_cstring(prompts[i]); 222 packet_put_char(echo_on[i]); 223 } 224 packet_send(); 225 packet_write_wait(); 226 227 for (i = 0; i < numprompts; i++) 228 xfree(prompts[i]); 229 xfree(prompts); 230 xfree(echo_on); 231 xfree(name); 232 xfree(instr); 233 return 1; 234 } 235 236 static void 237 input_userauth_info_response(int type, u_int32_t seq, void *ctxt) 238 { 239 Authctxt *authctxt = ctxt; 240 KbdintAuthctxt *kbdintctxt; 241 int i, authenticated = 0, res, len; 242 u_int nresp; 243 char **response = NULL, *method; 244 245 if (authctxt == NULL) 246 fatal("input_userauth_info_response: no authctxt"); 247 kbdintctxt = authctxt->kbdintctxt; 248 if (kbdintctxt == NULL || kbdintctxt->ctxt == NULL) 249 fatal("input_userauth_info_response: no kbdintctxt"); 250 if (kbdintctxt->device == NULL) 251 fatal("input_userauth_info_response: no device"); 252 253 authctxt->postponed = 0; /* reset */ 254 nresp = packet_get_int(); 255 if (nresp > 0) { 256 response = xmalloc(nresp * sizeof(char*)); 257 for (i = 0; i < nresp; i++) 258 response[i] = packet_get_string(NULL); 259 } 260 packet_check_eom(); 261 262 if (authctxt->valid) { 263 res = kbdintctxt->device->respond(kbdintctxt->ctxt, 264 nresp, response); 265 } else { 266 res = -1; 267 } 268 269 for (i = 0; i < nresp; i++) { 270 memset(response[i], 'r', strlen(response[i])); 271 xfree(response[i]); 272 } 273 if (response) 274 xfree(response); 275 276 switch (res) { 277 case 0: 278 /* Success! */ 279 authenticated = 1; 280 break; 281 case 1: 282 /* Authentication needs further interaction */ 283 if (send_userauth_info_request(authctxt) == 1) 284 authctxt->postponed = 1; 285 break; 286 default: 287 /* Failure! */ 288 break; 289 } 290 291 len = strlen("keyboard-interactive") + 2 + 292 strlen(kbdintctxt->device->name); 293 method = xmalloc(len); 294 method[0] = '\0'; 295 strlcat(method, "keyboard-interactive", len); 296 strlcat(method, "/", len); 297 strlcat(method, kbdintctxt->device->name, len); 298 299 if (!authctxt->postponed) { 300 if (authenticated) { 301 auth2_challenge_stop(authctxt); 302 } else { 303 /* start next device */ 304 /* may set authctxt->postponed */ 305 auth2_challenge_start(authctxt); 306 } 307 } 308 userauth_finish(authctxt, authenticated, method); 309 xfree(method); 310 } 311