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 <stdarg.h>
  34
  35 #include "xmalloc.h"
  36 #include "key.h"
  37 #include "hostfile.h"
  38 #include "auth.h"
  39 #include "log.h"
  40 #include "misc.h"
  41 #include "servconf.h"
  42
  43 /* limited protocol v1 interface to kbd-interactive authentication */
  44
  45 extern KbdintDevice *devices[];
  46 static KbdintDevice *device;
  47 extern ServerOptions options;
  48
  49 char *
  50 get_challenge(Authctxt *authctxt)
  51 {
  52         char *challenge, *name, *info, **prompts;
  53         u_int i, numprompts;
  54         u_int *echo_on;
  55
  56 #ifdef USE_PAM
  57         if (!options.use_pam)
  58                 remove_kbdint_device("pam");
  59 #endif
  60
  61         device = devices[0]; /* we always use the 1st device for protocol 1 */
  62         if (device == NULL)
  63                 return NULL;
  64         if ((authctxt->kbdintctxt = device->init_ctx(authctxt)) == NULL)
  65                 return NULL;
  66         if (device->query(authctxt->kbdintctxt, &name, &info,
  67             &numprompts, &prompts, &echo_on)) {
  68                 device->free_ctx(authctxt->kbdintctxt);
  69                 authctxt->kbdintctxt = NULL;
  70                 return NULL;
  71         }
  72         if (numprompts < 1)
  73                 fatal("get_challenge: numprompts < 1");
  74         challenge = xstrdup(prompts[0]);
  75         for (i = 0; i < numprompts; i++)
  76                 free(prompts[i]);
  77         free(prompts);
  78         free(name);
  79         free(echo_on);
  80         free(info);
  81
  82         return (challenge);
  83 }
  84 int
  85 verify_response(Authctxt *authctxt, const char *response)
  86 {
  87         char *resp[1], *name, *info, **prompts;
  88         u_int i, numprompts, *echo_on;
  89         int authenticated = 0;
  90
  91         if (device == NULL)
  92                 return 0;
  93         if (authctxt->kbdintctxt == NULL)
  94                 return 0;
  95         resp[0] = (char *)response;
  96         switch (device->respond(authctxt->kbdintctxt, 1, resp)) {
  97         case 0: /* Success */
  98                 authenticated = 1;
  99                 break;
 100         case 1: /* Postponed - retry with empty query for PAM */
 101                 if ((device->query(authctxt->kbdintctxt, &name, &info,
 102                     &numprompts, &prompts, &echo_on)) != 0)
 103                         break;
 104                 if (numprompts == 0 &&
 105                     device->respond(authctxt->kbdintctxt, 0, resp) == 0)
 106                         authenticated = 1;
 107
 108                 for (i = 0; i < numprompts; i++)
 109                         free(prompts[i]);
 110                 free(prompts);
 111                 free(name);
 112                 free(echo_on);
 113                 free(info);
 114                 break;
 115         }
 116         device->free_ctx(authctxt->kbdintctxt);
 117         authctxt->kbdintctxt = NULL;
 118         return authenticated;
 119 }
 120 void
 121 abandon_challenge_response(Authctxt *authctxt)
 122 {
 123         if (authctxt->kbdintctxt != NULL) {
 124                 device->free_ctx(authctxt->kbdintctxt);
 125                 authctxt->kbdintctxt = NULL;
 126         }
 127 }