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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: noise.h,v 1.6 2004/04/08 01:36:15 mdw Exp $ |
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4 | * |
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5 | * Acquisition of environmental noise (Unix-specific) |
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6 | * |
7 | * (c) 1998 Straylight/Edgeware |
8 | */ |
9 | |
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10 | /*----- Licensing notice --------------------------------------------------* |
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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. |
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18 | * |
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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. |
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23 | * |
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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 | |
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30 | #ifndef CATACOMB_NOISE_H |
31 | #define CATACOMB_NOISE_H |
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32 | |
33 | #ifdef __cplusplus |
34 | extern "C" { |
35 | #endif |
36 | |
37 | /*----- Header files ------------------------------------------------------*/ |
38 | |
39 | #include <sys/types.h> |
40 | |
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41 | #ifndef CATACOMB_RAND_H |
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42 | # include "rand.h" |
43 | #endif |
44 | |
45 | /*----- Noise source definition -------------------------------------------*/ |
46 | |
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47 | extern const rand_source noise_source; |
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48 | |
49 | /*----- Magic numbers -----------------------------------------------------*/ |
50 | |
51 | #define NOISE_NOSETUID ((uid_t)-1) |
52 | #define NOISE_NOSETGID ((gid_t)-1) |
53 | |
54 | /*----- Functions provided ------------------------------------------------*/ |
55 | |
56 | /* --- @noise_timer@ --- * |
57 | * |
58 | * Arguments: @rand_pool *r@ = pointer to a randomness pool |
59 | * |
60 | * Returns: Nonzero if some randomness was contributed. |
61 | * |
62 | * Use: Contributes the current time to the randomness pool. |
63 | * A guess at the number of useful bits contributed is made, |
64 | * based on first and second order bit differences. This isn't |
65 | * ever-so reliable, but it's better than nothing. |
66 | */ |
67 | |
68 | extern int noise_timer(rand_pool */*r*/); |
69 | |
70 | /* --- @noise_devrandom@ --- * |
71 | * |
72 | * Arguments: @rand_pool *r@ = pointer to a randomness pool |
73 | * |
74 | * Returns: Nonzero if some randomness was contributed. |
75 | * |
76 | * Use: Attempts to obtain some randomness from the system entropy |
77 | * pool. All bits from the device are assumed to be good. |
78 | */ |
79 | |
80 | extern int noise_devrandom(rand_pool */*r*/); |
81 | |
82 | /* --- @noise_setid@ --- * |
83 | * |
84 | * Arguments: @uid_t uid@ = uid to set |
85 | * @gid_t gid@ = gid to set |
86 | * |
87 | * Returns: --- |
88 | * |
89 | * Use: Sets the user and group ids to be used by @noise_filter@ |
90 | * when running child processes. This is useful to avoid |
91 | * giving shell commands (even carefully written ones) undue |
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92 | * privileges. This interface is Unix-specific. |
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93 | */ |
94 | |
95 | extern void noise_setid(uid_t /*uid*/, gid_t /*gid*/); |
96 | |
97 | /* --- @noise_filter@ --- * |
98 | * |
99 | * Arguments: @rand_pool *r@ = pointer to a randomness pool |
100 | * @int good@ = number of good bits per 1024 bits |
101 | * @const char *c@ = shell command to run |
102 | * |
103 | * Returns: Nonzero if some randomness was contributed. |
104 | * |
105 | * Use: Attempts to execute a shell command, and dump it into the |
106 | * randomness pool. A very rough estimate of the number of |
107 | * good bits is made, based on the size of the command's output. |
108 | * This function calls @waitpid@, so be careful. Before execing |
109 | * the command, the process uid and gid are set to the values |
110 | * given to @noise_setid@, and an attempt is made to reset the |
111 | * list of supplementary groups. The environment passed to |
112 | * the command has been severly lobotimized. If the command |
113 | * fails to complete within a short time period, it is killed. |
114 | * Paranoid use of close-on-exec flags for file descriptors is |
115 | * recommended. |
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116 | * |
117 | * This interface is Unix-specific. |
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118 | */ |
119 | |
120 | extern int noise_filter(rand_pool */*r*/, int /*good*/, const char */*c*/); |
121 | |
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122 | /* --- @noise_freewheel@ --- * |
123 | * |
124 | * Arguments: @rand_pool *r@ = pointer to a randomness pool |
125 | * |
126 | * Returns: Nonzero if some randomness was contributed. |
127 | * |
128 | * Use: Runs a free counter for a short while as a desparate attempt |
129 | * to get randomness from somewhere. This is actually quite |
130 | * effective. |
131 | */ |
132 | |
133 | int noise_freewheel(rand_pool */*r*/); |
134 | |
135 | /* --- @noise_enquire@ --- * |
136 | * |
137 | * Arguments: @rand_pool *r@ = pointer to a randomness pool |
138 | * |
139 | * Returns: Nonzero if some randomness was contributed. |
140 | * |
141 | * Use: Runs some shell commands to enquire about the prevailing |
142 | * environment. This can gather quite a lot of low-quality |
143 | * entropy. |
144 | */ |
145 | |
146 | extern int noise_enquire(rand_pool */*r*/); |
147 | |
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148 | /* --- @noise_acquire@ --- * |
149 | * |
150 | * Arguments: @rand_pool *r@ = pointer to a randomness pool |
151 | * |
152 | * Returns: --- |
153 | * |
154 | * Use: Acquires some randomness from somewhere. |
155 | */ |
156 | |
157 | extern void noise_acquire(rand_pool */*r*/); |
158 | |
159 | /*----- That's all, folks -------------------------------------------------*/ |
160 | |
161 | #ifdef __cplusplus |
162 | } |
163 | #endif |
164 | |
165 | #endif |