crypto/openssh-3.8.1p1/auth2-chall.c

   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 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 }