crypto/openssh-3.9p1/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 1.21 2004/06/01 14:20:45 dtucker 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 "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 USE_PAM
  44 extern KbdintDevice sshpam_device;
  45 #endif
  46 #ifdef SKEY
  47 extern KbdintDevice skey_device;
  48 #endif
  49 #endif
  50
  51 KbdintDevice *devices[] = {
  52 #ifdef BSD_AUTH
  53         &bsdauth_device,
  54 #else
  55 #ifdef USE_PAM
  56         &sshpam_device,
  57 #endif
  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         int i;
 219         u_int *echo_on;
 220
 221         kbdintctxt = authctxt->kbdintctxt;
 222         if (kbdintctxt->device->query(kbdintctxt->ctxt,
 223             &name, &instr, &kbdintctxt->nreq, &prompts, &echo_on))
 224                 return 0;
 225
 226         packet_start(SSH2_MSG_USERAUTH_INFO_REQUEST);
 227         packet_put_cstring(name);
 228         packet_put_cstring(instr);
 229         packet_put_cstring("");         /* language not used */
 230         packet_put_int(kbdintctxt->nreq);
 231         for (i = 0; i < kbdintctxt->nreq; i++) {
 232                 packet_put_cstring(prompts[i]);
 233                 packet_put_char(echo_on[i]);
 234         }
 235         packet_send();
 236         packet_write_wait();
 237
 238         for (i = 0; i < kbdintctxt->nreq; i++)
 239                 xfree(prompts[i]);
 240         xfree(prompts);
 241         xfree(echo_on);
 242         xfree(name);
 243         xfree(instr);
 244         return 1;
 245 }
 246
 247 static void
 248 input_userauth_info_response(int type, u_int32_t seq, void *ctxt)
 249 {
 250         Authctxt *authctxt = ctxt;
 251         KbdintAuthctxt *kbdintctxt;
 252         int i, authenticated = 0, res, len;
 253         u_int nresp;
 254         char **response = NULL, *method;
 255
 256         if (authctxt == NULL)
 257                 fatal("input_userauth_info_response: no authctxt");
 258         kbdintctxt = authctxt->kbdintctxt;
 259         if (kbdintctxt == NULL || kbdintctxt->ctxt == NULL)
 260                 fatal("input_userauth_info_response: no kbdintctxt");
 261         if (kbdintctxt->device == NULL)
 262                 fatal("input_userauth_info_response: no device");
 263
 264         authctxt->postponed = 0;        /* reset */
 265         nresp = packet_get_int();
 266         if (nresp != kbdintctxt->nreq)
 267                 fatal("input_userauth_info_response: wrong number of replies");
 268         if (nresp > 100)
 269                 fatal("input_userauth_info_response: too many replies");
 270         if (nresp > 0) {
 271                 response = xmalloc(nresp * sizeof(char *));
 272                 for (i = 0; i < nresp; i++)
 273                         response[i] = packet_get_string(NULL);
 274         }
 275         packet_check_eom();
 276
 277         if (authctxt->valid) {
 278                 res = kbdintctxt->device->respond(kbdintctxt->ctxt,
 279                     nresp, response);
 280         } else {
 281                 res = -1;
 282         }
 283
 284         for (i = 0; i < nresp; i++) {
 285                 memset(response[i], 'r', strlen(response[i]));
 286                 xfree(response[i]);
 287         }
 288         if (response)
 289                 xfree(response);
 290
 291         switch (res) {
 292         case 0:
 293                 /* Success! */
 294                 authenticated = 1;
 295                 break;
 296         case 1:
 297                 /* Authentication needs further interaction */
 298                 if (send_userauth_info_request(authctxt) == 1)
 299                         authctxt->postponed = 1;
 300                 break;
 301         default:
 302                 /* Failure! */
 303                 break;
 304         }
 305
 306         len = strlen("keyboard-interactive") + 2 +
 307                 strlen(kbdintctxt->device->name);
 308         method = xmalloc(len);
 309         snprintf(method, len, "keyboard-interactive/%s",
 310             kbdintctxt->device->name);
 311
 312         if (!authctxt->postponed) {
 313                 if (authenticated) {
 314                         auth2_challenge_stop(authctxt);
 315                 } else {
 316                         /* start next device */
 317                         /* may set authctxt->postponed */
 318                         auth2_challenge_start(authctxt);
 319                 }
 320         }
 321         userauth_finish(authctxt, authenticated, method);
 322         xfree(method);
 323 }
 324
 325 void
 326 privsep_challenge_enable(void)
 327 {
 328 #if defined(BSD_AUTH) || defined(USE_PAM) || defined(SKEY)
 329         int n = 0;
 330 #endif
 331 #ifdef BSD_AUTH
 332         extern KbdintDevice mm_bsdauth_device;
 333 #endif
 334 #ifdef USE_PAM
 335         extern KbdintDevice mm_sshpam_device;
 336 #endif
 337 #ifdef SKEY
 338         extern KbdintDevice mm_skey_device;
 339 #endif
 340
 341 #ifdef BSD_AUTH
 342         devices[n++] = &mm_bsdauth_device;
 343 #else
 344 #ifdef USE_PAM
 345         devices[n++] = &mm_sshpam_device;
 346 #endif
 347 #ifdef SKEY
 348         devices[n++] = &mm_skey_device;
 349 #endif
 350 #endif
 351 }