auth-chall.c

   1 /* $OpenBSD: auth-chall.c,v 1.11 2006/03/25 13:17:01 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 "auth.h"
  29 #include "log.h"
  30 #include "xmalloc.h"
  31 #include "servconf.h"
  32
  33 /* limited protocol v1 interface to kbd-interactive authentication */
  34
  35 extern KbdintDevice *devices[];
  36 static KbdintDevice *device;
  37 extern ServerOptions options;
  38
  39 char *
  40 get_challenge(Authctxt *authctxt)
  41 {
  42         char *challenge, *name, *info, **prompts;
  43         u_int i, numprompts;
  44         u_int *echo_on;
  45
  46 #ifdef USE_PAM
  47         if (!options.use_pam)
  48                 remove_kbdint_device("pam");
  49 #endif
  50
  51         device = devices[0]; /* we always use the 1st device for protocol 1 */
  52         if (device == NULL)
  53                 return NULL;
  54         if ((authctxt->kbdintctxt = device->init_ctx(authctxt)) == NULL)
  55                 return NULL;
  56         if (device->query(authctxt->kbdintctxt, &name, &info,
  57             &numprompts, &prompts, &echo_on)) {
  58                 device->free_ctx(authctxt->kbdintctxt);
  59                 authctxt->kbdintctxt = NULL;
  60                 return NULL;
  61         }
  62         if (numprompts < 1)
  63                 fatal("get_challenge: numprompts < 1");
  64         challenge = xstrdup(prompts[0]);
  65         for (i = 0; i < numprompts; i++)
  66                 xfree(prompts[i]);
  67         xfree(prompts);
  68         xfree(name);
  69         xfree(echo_on);
  70         xfree(info);
  71
  72         return (challenge);
  73 }
  74 int
  75 verify_response(Authctxt *authctxt, const char *response)
  76 {
  77         char *resp[1], *name, *info, **prompts;
  78         u_int i, numprompts, *echo_on;
  79         int authenticated = 0;
  80
  81         if (device == NULL)
  82                 return 0;
  83         if (authctxt->kbdintctxt == NULL)
  84                 return 0;
  85         resp[0] = (char *)response;
  86         switch (device->respond(authctxt->kbdintctxt, 1, resp)) {
  87         case 0: /* Success */
  88                 authenticated = 1;
  89                 break;
  90         case 1: /* Postponed - retry with empty query for PAM */
  91                 if ((device->query(authctxt->kbdintctxt, &name, &info,
  92                     &numprompts, &prompts, &echo_on)) != 0)
  93                         break;
  94                 if (numprompts == 0 &&
  95                     device->respond(authctxt->kbdintctxt, 0, resp) == 0)
  96                         authenticated = 1;
  97
  98                 for (i = 0; i < numprompts; i++)
  99                         xfree(prompts[i]);
 100                 xfree(prompts);
 101                 xfree(name);
 102                 xfree(echo_on);
 103                 xfree(info);
 104                 break;
 105         }
 106         device->free_ctx(authctxt->kbdintctxt);
 107         authctxt->kbdintctxt = NULL;
 108         return authenticated;
 109 }
 110 void
 111 abandon_challenge_response(Authctxt *authctxt)
 112 {
 113         if (authctxt->kbdintctxt != NULL) {
 114                 device->free_ctx(authctxt->kbdintctxt);
 115                 authctxt->kbdintctxt = NULL;
 116         }
 117 }