auth-chall.c

   1 /* $OpenBSD: auth-chall.c,v 1.12 2006/08/03 03:34:41 deraadt 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
  30 #include <stdarg.h>
  31
  32 #include "xmalloc.h"
  33 #include "key.h"
  34 #include "hostfile.h"
  35 #include "auth.h"
  36 #include "log.h"
  37 #include "servconf.h"
  38
  39 /* limited protocol v1 interface to kbd-interactive authentication */
  40
  41 extern KbdintDevice *devices[];
  42 static KbdintDevice *device;
  43 extern ServerOptions options;
  44
  45 char *
  46 get_challenge(Authctxt *authctxt)
  47 {
  48         char *challenge, *name, *info, **prompts;
  49         u_int i, numprompts;
  50         u_int *echo_on;
  51
  52 #ifdef USE_PAM
  53         if (!options.use_pam)
  54                 remove_kbdint_device("pam");
  55 #endif
  56
  57         device = devices[0]; /* we always use the 1st device for protocol 1 */
  58         if (device == NULL)
  59                 return NULL;
  60         if ((authctxt->kbdintctxt = device->init_ctx(authctxt)) == NULL)
  61                 return NULL;
  62         if (device->query(authctxt->kbdintctxt, &name, &info,
  63             &numprompts, &prompts, &echo_on)) {
  64                 device->free_ctx(authctxt->kbdintctxt);
  65                 authctxt->kbdintctxt = NULL;
  66                 return NULL;
  67         }
  68         if (numprompts < 1)
  69                 fatal("get_challenge: numprompts < 1");
  70         challenge = xstrdup(prompts[0]);
  71         for (i = 0; i < numprompts; i++)
  72                 xfree(prompts[i]);
  73         xfree(prompts);
  74         xfree(name);
  75         xfree(echo_on);
  76         xfree(info);
  77
  78         return (challenge);
  79 }
  80 int
  81 verify_response(Authctxt *authctxt, const char *response)
  82 {
  83         char *resp[1], *name, *info, **prompts;
  84         u_int i, numprompts, *echo_on;
  85         int authenticated = 0;
  86
  87         if (device == NULL)
  88                 return 0;
  89         if (authctxt->kbdintctxt == NULL)
  90                 return 0;
  91         resp[0] = (char *)response;
  92         switch (device->respond(authctxt->kbdintctxt, 1, resp)) {
  93         case 0: /* Success */
  94                 authenticated = 1;
  95                 break;
  96         case 1: /* Postponed - retry with empty query for PAM */
  97                 if ((device->query(authctxt->kbdintctxt, &name, &info,
  98                     &numprompts, &prompts, &echo_on)) != 0)
  99                         break;
 100                 if (numprompts == 0 &&
 101                     device->respond(authctxt->kbdintctxt, 0, resp) == 0)
 102                         authenticated = 1;
 103
 104                 for (i = 0; i < numprompts; i++)
 105                         xfree(prompts[i]);
 106                 xfree(prompts);
 107                 xfree(name);
 108                 xfree(echo_on);
 109                 xfree(info);
 110                 break;
 111         }
 112         device->free_ctx(authctxt->kbdintctxt);
 113         authctxt->kbdintctxt = NULL;
 114         return authenticated;
 115 }
 116 void
 117 abandon_challenge_response(Authctxt *authctxt)
 118 {
 119         if (authctxt->kbdintctxt != NULL) {
 120                 device->free_ctx(authctxt->kbdintctxt);
 121                 authctxt->kbdintctxt = NULL;
 122         }
 123 }