| 1 | /* -*-c-*- |
| 2 | * |
| 3 | * Acquisition of environmental noise (Unix-specific) |
| 4 | * |
| 5 | * (c) 1998 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 |
| 13 | * it under the terms of the GNU Library General Public License as |
| 14 | * published by the Free Software Foundation; either version 2 of the |
| 15 | * License, or (at your option) any later version. |
| 16 | * |
| 17 | * Catacomb is distributed in the hope that it will be useful, |
| 18 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 20 | * GNU 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 |
| 24 | * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, |
| 25 | * MA 02111-1307, USA. |
| 26 | */ |
| 27 | |
| 28 | #ifndef CATACOMB_NOISE_H |
| 29 | #define CATACOMB_NOISE_H |
| 30 | |
| 31 | #ifdef __cplusplus |
| 32 | extern "C" { |
| 33 | #endif |
| 34 | |
| 35 | /*----- Header files ------------------------------------------------------*/ |
| 36 | |
| 37 | #include <sys/types.h> |
| 38 | |
| 39 | #ifndef CATACOMB_RAND_H |
| 40 | # include "rand.h" |
| 41 | #endif |
| 42 | |
| 43 | /*----- Noise source definition -------------------------------------------*/ |
| 44 | |
| 45 | extern const rand_source noise_source; |
| 46 | |
| 47 | /*----- Magic numbers -----------------------------------------------------*/ |
| 48 | |
| 49 | #define NOISE_NOSETUID ((uid_t)-1) |
| 50 | #define NOISE_NOSETGID ((gid_t)-1) |
| 51 | |
| 52 | /*----- Functions provided ------------------------------------------------*/ |
| 53 | |
| 54 | /* --- @noise_timer@ --- * |
| 55 | * |
| 56 | * Arguments: @rand_pool *r@ = pointer to a randomness pool |
| 57 | * |
| 58 | * Returns: Nonzero if some randomness was contributed. |
| 59 | * |
| 60 | * Use: Contributes the current time to the randomness pool. |
| 61 | * A guess at the number of useful bits contributed is made, |
| 62 | * based on first and second order bit differences. This isn't |
| 63 | * ever-so reliable, but it's better than nothing. |
| 64 | */ |
| 65 | |
| 66 | extern int noise_timer(rand_pool */*r*/); |
| 67 | |
| 68 | /* --- @noise_devrandom@ --- * |
| 69 | * |
| 70 | * Arguments: @rand_pool *r@ = pointer to a randomness pool |
| 71 | * |
| 72 | * Returns: Nonzero if some randomness was contributed. |
| 73 | * |
| 74 | * Use: Attempts to obtain some randomness from the system entropy |
| 75 | * pool. All bits from the device are assumed to be good. |
| 76 | */ |
| 77 | |
| 78 | extern int noise_devrandom(rand_pool */*r*/); |
| 79 | |
| 80 | /* --- @noise_setid@ --- * |
| 81 | * |
| 82 | * Arguments: @uid_t uid@ = uid to set |
| 83 | * @gid_t gid@ = gid to set |
| 84 | * |
| 85 | * Returns: --- |
| 86 | * |
| 87 | * Use: Sets the user and group ids to be used by @noise_filter@ |
| 88 | * when running child processes. This is useful to avoid |
| 89 | * giving shell commands (even carefully written ones) undue |
| 90 | * privileges. This interface is Unix-specific. |
| 91 | */ |
| 92 | |
| 93 | extern void noise_setid(uid_t /*uid*/, gid_t /*gid*/); |
| 94 | |
| 95 | /* --- @noise_filter@ --- * |
| 96 | * |
| 97 | * Arguments: @rand_pool *r@ = pointer to a randomness pool |
| 98 | * @int good@ = number of good bits per 1024 bits |
| 99 | * @const char *c@ = shell command to run |
| 100 | * |
| 101 | * Returns: Nonzero if some randomness was contributed. |
| 102 | * |
| 103 | * Use: Attempts to execute a shell command, and dump it into the |
| 104 | * randomness pool. A very rough estimate of the number of |
| 105 | * good bits is made, based on the size of the command's output. |
| 106 | * This function calls @waitpid@, so be careful. Before execing |
| 107 | * the command, the process uid and gid are set to the values |
| 108 | * given to @noise_setid@, and an attempt is made to reset the |
| 109 | * list of supplementary groups. The environment passed to |
| 110 | * the command has been severly lobotimized. If the command |
| 111 | * fails to complete within a short time period, it is killed. |
| 112 | * Paranoid use of close-on-exec flags for file descriptors is |
| 113 | * recommended. |
| 114 | * |
| 115 | * This interface is Unix-specific. |
| 116 | */ |
| 117 | |
| 118 | extern int noise_filter(rand_pool */*r*/, int /*good*/, const char */*c*/); |
| 119 | |
| 120 | /* --- @noise_freewheel@ --- * |
| 121 | * |
| 122 | * Arguments: @rand_pool *r@ = pointer to a randomness pool |
| 123 | * |
| 124 | * Returns: Nonzero if some randomness was contributed. |
| 125 | * |
| 126 | * Use: Runs a free counter for a short while as a desparate attempt |
| 127 | * to get randomness from somewhere. This is actually quite |
| 128 | * effective. |
| 129 | */ |
| 130 | |
| 131 | int noise_freewheel(rand_pool */*r*/); |
| 132 | |
| 133 | /* --- @noise_enquire@ --- * |
| 134 | * |
| 135 | * Arguments: @rand_pool *r@ = pointer to a randomness pool |
| 136 | * |
| 137 | * Returns: Nonzero if some randomness was contributed. |
| 138 | * |
| 139 | * Use: Runs some shell commands to enquire about the prevailing |
| 140 | * environment. This can gather quite a lot of low-quality |
| 141 | * entropy. |
| 142 | */ |
| 143 | |
| 144 | extern int noise_enquire(rand_pool */*r*/); |
| 145 | |
| 146 | /* --- @noise_acquire@ --- * |
| 147 | * |
| 148 | * Arguments: @rand_pool *r@ = pointer to a randomness pool |
| 149 | * |
| 150 | * Returns: --- |
| 151 | * |
| 152 | * Use: Acquires some randomness from somewhere. |
| 153 | */ |
| 154 | |
| 155 | extern void noise_acquire(rand_pool */*r*/); |
| 156 | |
| 157 | /*----- That's all, folks -------------------------------------------------*/ |
| 158 | |
| 159 | #ifdef __cplusplus |
| 160 | } |
| 161 | #endif |
| 162 | |
| 163 | #endif |