mdw@git.distorted.org.uk Git - catacomb/blob - base/ct-test.c

   1 /* -*-c-*-
   2  *
   3  * Utilities for verifying constant-time programming
   4  *
   5  * (c) 2017 Straylight/Edgeware
   6  */
   7
   8 /*----- Licensing notice --------------------------------------------------*
   9  *
  10  * This file is part of Catacomb.
  11  *
  12  * Catacomb is free software: you can redistribute it and/or modify it
  13  * under the terms of the GNU Library General Public License as published
  14  * by the Free Software Foundation; either version 2 of the License, or
  15  * (at your option) any later version.
  16  *
  17  * Catacomb is distributed in the hope that it will be useful, but
  18  * WITHOUT ANY WARRANTY; without even the implied warranty of
  19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  20  * Library General Public License for more details.
  21  *
  22  * You should have received a copy of the GNU Library General Public
  23  * License along with Catacomb.  If not, write to the Free Software
  24  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
  25  * USA.
  26  */
  27
  28 /*----- Header files ------------------------------------------------------*/
  29
  30 #include "config.h"
  31
  32 #include "ct.h"
  33
  34 #ifdef HAVE_VALGRIND_H
  35 #  include <valgrind/valgrind.h>
  36 #  include <valgrind/memcheck.h>
  37 #endif
  38
  39 /*----- Main code ---------------------------------------------------------*/
  40
  41 /* --- @ct_poison@ --- *
  42  *
  43  * Arguments:   @const void *p@ = pointer to a secret
  44  *              @size_t sz@ = size of the secret
  45  *
  46  * Returns:     ---
  47  *
  48  * Use:         Ordinarily, does nothing.  If the process is running under
  49  *              the control of Valgrind's `memcheck' utility, then mark the
  50  *              secret as `uninitialized', so that Valgrind warns about
  51  *              conditional execution or memory addressing based on the value
  52  *              of the secret.
  53  *
  54  *              Credit for this idea goes to Adam Langley, who described it
  55  *              in https://www.imperialviolet.org/2010/04/01/ctgrind.html,
  56  *              though this implementation doesn't require patching Valgrind.
  57  */
  58
  59 void ct_poison(const void *p, size_t sz)
  60 {
  61 #ifdef HAVE_VALGRIND_H
  62   VALGRIND_MAKE_MEM_UNDEFINED(p, sz);
  63 #endif
  64 }
  65
  66 /* --- @ct_remedy@ --- *
  67  *
  68  * Arguments:   @const void *p@ = pointer to a secret
  69  *              @size_t sz@ = size of the secret
  70  *
  71  * Returns:     ---
  72  *
  73  * Use:         Ordinarily, does nothing.  If the process is running under
  74  *              the control of Valgrind's `memcheck' utility, then mark the
  75  *              secret as `initialized'.  This is intended to reverse the
  76  *              effect of @ct_poison@ so that a test program can verify
  77  *              function outputs wihtout Valgrind warning.
  78  */
  79
  80 void ct_remedy(const void *p, size_t sz)
  81 {
  82 #ifdef HAVE_VALGRIND_H
  83   VALGRIND_MAKE_MEM_DEFINED(p, sz);
  84 #endif
  85 }
  86
  87 /*----- That's all, folks -------------------------------------------------*/