crypto/openssh/auth-chall.c

   1 /* $OpenBSD: auth-chall.c,v 1.14 2014/06/24 01:13:21 djm Exp $ */
   2 /*
   3  * Copyright (c) 2001 Markus Friedl.  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
  26 #include "includes.h"
  27
  28 #include <sys/types.h>
  29 #include <stdarg.h>
  30 #include <stdlib.h>
  31 #include <stdio.h>
  32
  33 #include "xmalloc.h"
  34 #include "key.h"
  35 #include "hostfile.h"
  36 #include "auth.h"
  37 #include "log.h"
  38 #include "misc.h"
  39 #include "servconf.h"
  40
  41 /* limited protocol v1 interface to kbd-interactive authentication */
  42
  43 extern KbdintDevice *devices[];
  44 static KbdintDevice *device;
  45 extern ServerOptions options;
  46
  47 char *
  48 get_challenge(Authctxt *authctxt)
  49 {
  50         char *challenge, *name, *info, **prompts;
  51         u_int i, numprompts;
  52         u_int *echo_on;
  53
  54 #ifdef USE_PAM
  55         if (!options.use_pam)
  56                 remove_kbdint_device("pam");
  57 #endif
  58
  59         device = devices[0]; /* we always use the 1st device for protocol 1 */
  60         if (device == NULL)
  61                 return NULL;
  62         if ((authctxt->kbdintctxt = device->init_ctx(authctxt)) == NULL)
  63                 return NULL;
  64         if (device->query(authctxt->kbdintctxt, &name, &info,
  65             &numprompts, &prompts, &echo_on)) {
  66                 device->free_ctx(authctxt->kbdintctxt);
  67                 authctxt->kbdintctxt = NULL;
  68                 return NULL;
  69         }
  70         if (numprompts < 1)
  71                 fatal("get_challenge: numprompts < 1");
  72         challenge = xstrdup(prompts[0]);
  73         for (i = 0; i < numprompts; i++)
  74                 free(prompts[i]);
  75         free(prompts);
  76         free(name);
  77         free(echo_on);
  78         free(info);
  79
  80         return (challenge);
  81 }
  82 int
  83 verify_response(Authctxt *authctxt, const char *response)
  84 {
  85         char *resp[1], *name, *info, **prompts;
  86         u_int i, numprompts, *echo_on;
  87         int authenticated = 0;
  88
  89         if (device == NULL)
  90                 return 0;
  91         if (authctxt->kbdintctxt == NULL)
  92                 return 0;
  93         resp[0] = (char *)response;
  94         switch (device->respond(authctxt->kbdintctxt, 1, resp)) {
  95         case 0: /* Success */
  96                 authenticated = 1;
  97                 break;
  98         case 1: /* Postponed - retry with empty query for PAM */
  99                 if ((device->query(authctxt->kbdintctxt, &name, &info,
 100                     &numprompts, &prompts, &echo_on)) != 0)
 101                         break;
 102                 if (numprompts == 0 &&
 103                     device->respond(authctxt->kbdintctxt, 0, resp) == 0)
 104                         authenticated = 1;
 105
 106                 for (i = 0; i < numprompts; i++)
 107                         free(prompts[i]);
 108                 free(prompts);
 109                 free(name);
 110                 free(echo_on);
 111                 free(info);
 112                 break;
 113         }
 114         device->free_ctx(authctxt->kbdintctxt);
 115         authctxt->kbdintctxt = NULL;
 116         return authenticated;
 117 }
 118 void
 119 abandon_challenge_response(Authctxt *authctxt)
 120 {
 121         if (authctxt->kbdintctxt != NULL) {
 122                 device->free_ctx(authctxt->kbdintctxt);
 123                 authctxt->kbdintctxt = NULL;
 124         }
 125 }