git.distorted.org.uk Git - u/mdw/catacomb/blob - noise.h

   1 /* -*-c-*-
   2  *
   3  * $Id: noise.h,v 1.2 1999/12/10 23:29:48 mdw Exp $
   4  *
   5  * Acquisition of environmental noise (Unix specific)
   6  *
   7  * (c) 1998 Straylight/Edgeware
   8  */
   9
  10 /*----- Licensing notice --------------------------------------------------*
  11  *
  12  * This file is part of Catacomb.
  13  *
  14  * Catacomb is free software; you can redistribute it and/or modify
  15  * it under the terms of the GNU Library General Public License as
  16  * published by the Free Software Foundation; either version 2 of the
  17  * License, or (at your option) any later version.
  18  *
  19  * Catacomb is distributed in the hope that it will be useful,
  20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22  * GNU Library General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU Library General Public
  25  * License along with Catacomb; if not, write to the Free
  26  * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
  27  * MA 02111-1307, USA.
  28  */
  29
  30 /*----- Revision history --------------------------------------------------*
  31  *
  32  * $Log: noise.h,v $
  33  * Revision 1.2  1999/12/10 23:29:48  mdw
  34  * Change header file guard names.
  35  *
  36  * Revision 1.1  1999/09/03 08:41:12  mdw
  37  * Initial import.
  38  *
  39  */
  40
  41 #ifndef CATACOMB_NOISE_H
  42 #define CATACOMB_NOISE_H
  43
  44 #ifdef __cplusplus
  45   extern "C" {
  46 #endif
  47
  48 /*----- Header files ------------------------------------------------------*/
  49
  50 #include <sys/types.h>
  51
  52 #ifndef CATACOMB_RAND_H
  53 #  include "rand.h"
  54 #endif
  55
  56 /*----- Noise source definition -------------------------------------------*/
  57
  58 extern rand_source noise_source;
  59
  60 /*----- Magic numbers -----------------------------------------------------*/
  61
  62 #define NOISE_NOSETUID ((uid_t)-1)
  63 #define NOISE_NOSETGID ((gid_t)-1)
  64
  65 /*----- Functions provided ------------------------------------------------*/
  66
  67 /* --- @noise_timer@ --- *
  68  *
  69  * Arguments:   @rand_pool *r@ = pointer to a randomness pool
  70  *
  71  * Returns:     Nonzero if some randomness was contributed.
  72  *
  73  * Use:         Contributes the current time to the randomness pool.
  74  *              A guess at the number of useful bits contributed is made,
  75  *              based on first and second order bit differences.  This isn't
  76  *              ever-so reliable, but it's better than nothing.
  77  */
  78
  79 extern int noise_timer(rand_pool */*r*/);
  80
  81 /* --- @noise_devrandom@ --- *
  82  *
  83  * Arguments:   @rand_pool *r@ = pointer to a randomness pool
  84  *
  85  * Returns:     Nonzero if some randomness was contributed.
  86  *
  87  * Use:         Attempts to obtain some randomness from the system entropy
  88  *              pool.  All bits from the device are assumed to be good.
  89  */
  90
  91 extern int noise_devrandom(rand_pool */*r*/);
  92
  93 /* --- @noise_setid@ --- *
  94  *
  95  * Arguments:   @uid_t uid@ = uid to set
  96  *              @gid_t gid@ = gid to set
  97  *
  98  * Returns:     ---
  99  *
 100  * Use:         Sets the user and group ids to be used by @noise_filter@
 101  *              when running child processes.  This is useful to avoid
 102  *              giving shell commands (even carefully written ones) undue
 103  *              privileges.
 104  */
 105
 106 extern void noise_setid(uid_t /*uid*/, gid_t /*gid*/);
 107
 108 /* --- @noise_filter@ --- *
 109  *
 110  * Arguments:   @rand_pool *r@ = pointer to a randomness pool
 111  *              @int good@ = number of good bits per 1024 bits
 112  *              @const char *c@ = shell command to run
 113  *
 114  * Returns:     Nonzero if some randomness was contributed.
 115  *
 116  * Use:         Attempts to execute a shell command, and dump it into the
 117  *              randomness pool.  A very rough estimate of the number of
 118  *              good bits is made, based on the size of the command's output.
 119  *              This function calls @waitpid@, so be careful.  Before execing
 120  *              the command, the process uid and gid are set to the values
 121  *              given to @noise_setid@, and an attempt is made to reset the
 122  *              list of supplementary groups.  The environment passed to
 123  *              the command has been severly lobotimized.  If the command
 124  *              fails to complete within a short time period, it is killed.
 125  *              Paranoid use of close-on-exec flags for file descriptors is
 126  *              recommended.
 127  */
 128
 129 extern int noise_filter(rand_pool */*r*/, int /*good*/, const char */*c*/);
 130
 131 /* --- @noise_acquire@ --- *
 132  *
 133  * Arguments:   @rand_pool *r@ = pointer to a randomness pool
 134  *
 135  * Returns:     ---
 136  *
 137  * Use:         Acquires some randomness from somewhere.
 138  */
 139
 140 extern void noise_acquire(rand_pool */*r*/);
 141
 142 /*----- That's all, folks -------------------------------------------------*/
 143
 144 #ifdef __cplusplus
 145   }
 146 #endif
 147
 148 #endif