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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: noise.c,v 1.5 1998/04/23 13:25:23 mdw Exp $ |
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4 | * |
5 | * Collection of environmental noise |
6 | * |
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7 | * (c) 1998 EBI |
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8 | */ |
9 | |
10 | /*----- Licensing notice --------------------------------------------------* |
11 | * |
12 | * This file is part of `become' |
13 | * |
14 | * `Become' is free software; you can redistribute it and/or modify |
15 | * it under the terms of the GNU General Public License as published by |
16 | * the Free Software Foundation; either version 2 of the License, or |
17 | * (at your option) any later version. |
18 | * |
19 | * `Become' 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 General Public License for more details. |
23 | * |
24 | * You should have received a copy of the GNU General Public License |
25 | * along with `become'; if not, write to the Free Software Foundation, |
26 | * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
27 | */ |
28 | |
29 | /*----- Revision history --------------------------------------------------* |
30 | * |
31 | * $Log: noise.c,v $ |
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32 | * Revision 1.5 1998/04/23 13:25:23 mdw |
33 | * Try to reduce the amount of `ps'ing done under OSF/1, because /dev/kmem |
34 | * seems very slow. |
35 | * |
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36 | * Revision 1.4 1998/02/20 17:52:32 mdw |
37 | * Don't use `df' for noise gathering, because it gets upset when NFS |
38 | * servers aren't responding. |
39 | * |
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40 | * Revision 1.3 1998/01/12 16:46:19 mdw |
41 | * Fix copyright date. |
42 | * |
43 | * Revision 1.2 1997/08/20 16:19:57 mdw |
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44 | * Fix test for `/dev/random' so that it doesn't close `stdin' if it fails! |
45 | * |
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46 | * Revision 1.1 1997/08/07 09:45:26 mdw |
47 | * New source file added to acquire environmental noise and add it to the |
48 | * randomness pool (see `rand.c'). |
49 | * |
50 | */ |
51 | |
52 | /*----- Header files ------------------------------------------------------*/ |
53 | |
54 | /* --- ANSI headers --- */ |
55 | |
56 | #include <ctype.h> |
57 | #include <errno.h> |
58 | #include <stdio.h> |
59 | #include <stdlib.h> |
60 | #include <string.h> |
61 | #include <time.h> |
62 | |
63 | /* --- Unix headers --- */ |
64 | |
65 | #include <sys/types.h> |
66 | #include <sys/time.h> |
67 | |
68 | #include "config.h" |
69 | #if defined(HAVE_GETRUSAGE) |
70 | # include <sys/resource.h> |
71 | #elif defined(HAVE_VTIMES) |
72 | # include <sys/vtimes.h> |
73 | #endif |
74 | |
75 | #include <sys/wait.h> |
76 | |
77 | #include <fcntl.h> |
78 | #include <unistd.h> |
79 | |
80 | /* --- Local headers --- */ |
81 | |
82 | #include "noise.h" |
83 | #include "rand.h" |
84 | #include "utils.h" |
85 | |
86 | /*----- Main code ---------------------------------------------------------*/ |
87 | |
88 | /* --- @noise__shell@ --- * |
89 | * |
90 | * Arguments: @const char *cmd@ = pointer to a shell command |
91 | * |
92 | * Returns: --- |
93 | * |
94 | * Use: Adds the output of the shell command to the randomness pool. |
95 | * Some care is taken to do the Right Thing when running setuid. |
96 | */ |
97 | |
98 | static void noise__shell(const char *cmd) |
99 | { |
100 | int pfd[2]; |
101 | pid_t pid; |
102 | |
103 | /* --- Create a pipe for talking to the child --- */ |
104 | |
105 | if (pipe(pfd)) |
106 | return; |
107 | |
108 | /* --- Create the child process --- */ |
109 | |
110 | pid = fork(); |
111 | if (pid < 0) |
112 | return; |
113 | |
114 | if (pid == 0) { |
115 | int fd; |
116 | char *argv[] = { "/bin/sh", "-c", 0, 0 }; |
117 | char *env[] = { |
118 | "PATH=/bin:/usr/bin:/usr/ucb:/usr/etc:/sbin:/usr/sbin", |
119 | 0 |
120 | }; |
121 | |
122 | /* --- Become whoever I'm being run as --- */ |
123 | |
124 | setuid(getuid()); |
125 | |
126 | /* --- Close the old standard streams --- */ |
127 | |
128 | close(0); |
129 | close(1); |
130 | close(2); |
131 | |
132 | /* --- Set up stdin and stderr to be empty, and stdout as our pipe --- */ |
133 | |
134 | if (((fd = open("/dev/null", O_RDONLY)) != 0 && |
135 | (fd = dup2(fd, 0)) != 0) || |
136 | ((fd = dup2(pfd[1], 1)) != 1) || |
137 | ((fd = open("/dev/null", O_WRONLY)) != 2 && |
138 | (fd = dup2(fd, 2)) != 2)) |
139 | goto child_fail; |
140 | |
141 | /* --- Close the original pipe file descriptors --- */ |
142 | |
143 | close(pfd[0]); |
144 | close(pfd[1]); |
145 | burn(pfd); |
146 | |
147 | /* --- Now run the child process --- */ |
148 | |
149 | argv[2] = (char *)cmd; /* POSIX screwed up the prototype */ |
150 | execve("/bin/sh", argv, env); |
151 | |
152 | /* --- Something went horribly wrong --- */ |
153 | |
154 | child_fail: |
155 | _exit(127); |
156 | } |
157 | |
158 | /* --- Now read from the child until it's all done --- */ |
159 | |
160 | { |
161 | char buf[1024]; |
162 | ssize_t sz; |
163 | |
164 | close(pfd[1]); |
165 | for (;;) { |
166 | sz = read(pfd[0], buf, sizeof(buf)); |
167 | if (sz == 0 || (sz < 0 && sz != EINTR)) |
168 | break; |
169 | rand_add(buf, sz); |
170 | } |
171 | close(pfd[0]); |
172 | rand_add(pfd, sizeof(pfd)); |
173 | burn(buf); burn(pfd); |
174 | } |
175 | |
176 | /* --- The child should be dead now, so wait for it --- */ |
177 | |
178 | { |
179 | int st; |
180 | |
181 | wait(&st); |
182 | rand_add(&st, sizeof(st)); |
183 | rand_add(&pid, sizeof(pid)); |
184 | } |
185 | } |
186 | |
187 | /* --- @noise_acquire@ --- * |
188 | * |
189 | * Arguments: --- |
190 | * |
191 | * Returns: --- |
192 | * |
193 | * Use: Attempts to acquire an amount of random noise from the |
194 | * environment. A lot of it's not actually much good, but |
195 | * it's better than nothing. There's probably a bit or two's |
196 | * worth in each item which gets added. |
197 | */ |
198 | |
199 | void noise_acquire(void) |
200 | { |
201 | /* --- Try a real random number source --- * |
202 | * |
203 | * Some operating systems (notably Linux) provide a `/dev/random' which |
204 | * contains distilled random numbers from the outside world. |
205 | */ |
206 | |
207 | { |
208 | int fd; |
209 | int f; |
210 | unsigned char buff[64]; |
211 | ssize_t sz; |
212 | |
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213 | if ((fd = open("/dev/random", O_RDONLY)) >= 0 && |
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214 | (f = fcntl(fd, F_GETFL, 0)) >= 0 && |
215 | fcntl(fd, F_SETFL, f | O_NONBLOCK) >= 0 && |
216 | (sz = read(fd, buff, sizeof(buff))) > 0) { |
217 | rand_add(buff, sz); |
218 | burn(buff); |
219 | } |
220 | if (fd >= 0) |
221 | close(fd); |
222 | } |
223 | |
224 | /* --- Squeeze some entropy from the current time --- */ |
225 | |
226 | { |
227 | struct timeval tv; |
228 | clock_t c; |
229 | |
230 | gettimeofday(&tv, 0); |
231 | c = clock(); |
232 | rand_add(&tv, sizeof(tv)); |
233 | rand_add(&c, sizeof(c)); |
234 | burn(tv); burn(c); |
235 | } |
236 | |
237 | /* --- Try some commands which ask the outside world some questions --- */ |
238 | |
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239 | noise__shell("ps auxww || ps -ef; netstat -an"); |
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240 | |
241 | /* --- Get our resource usage to see if that's at all interesting --- */ |
242 | |
243 | #if defined(HAVE_GETRUSAGE) |
244 | { |
245 | struct rusage ru; |
246 | getrusage(RUSAGE_SELF, &ru); |
247 | rand_add(&ru, sizeof(ru)); |
248 | getrusage(RUSAGE_CHILDREN, &ru); |
249 | rand_add(&ru, sizeof(ru)); |
250 | burn(ru); |
251 | } |
252 | #elif defined(HAVE_VTIMES) |
253 | { |
254 | struct vtimes vt, vtc; |
255 | vtimes(&vt, &vtc); |
256 | rand_add(&vt, sizeof(vt)); |
257 | rand_add(&vtc, sizeof(vtc)); |
258 | burn(vt); burn(vtc); |
259 | } |
260 | #endif |
261 | |
262 | /* --- Squeeze some more entropy from the current time --- */ |
263 | |
264 | { |
265 | struct timeval tv; |
266 | clock_t c; |
267 | |
268 | gettimeofday(&tv, 0); |
269 | c = clock(); |
270 | rand_add(&tv, sizeof(tv)); |
271 | rand_add(&c, sizeof(c)); |
272 | burn(tv); burn(c); |
273 | } |
274 | |
275 | /* --- Done -- churn the random pool --- */ |
276 | |
277 | rand_churn(); |
278 | } |
279 | |
280 | /*----- That's all, folks -------------------------------------------------*/ |