d9fd0b20 |
1 | /* -*-c-*- |
2 | * |
3 | * $Id: noise.c,v 1.1 1997/08/07 09:45:26 mdw Exp $ |
4 | * |
5 | * Collection of environmental noise |
6 | * |
7 | * (c) 1997 EBI |
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 $ |
32 | * Revision 1.1 1997/08/07 09:45:26 mdw |
33 | * New source file added to acquire environmental noise and add it to the |
34 | * randomness pool (see `rand.c'). |
35 | * |
36 | */ |
37 | |
38 | /*----- Header files ------------------------------------------------------*/ |
39 | |
40 | /* --- ANSI headers --- */ |
41 | |
42 | #include <ctype.h> |
43 | #include <errno.h> |
44 | #include <stdio.h> |
45 | #include <stdlib.h> |
46 | #include <string.h> |
47 | #include <time.h> |
48 | |
49 | /* --- Unix headers --- */ |
50 | |
51 | #include <sys/types.h> |
52 | #include <sys/time.h> |
53 | |
54 | #include "config.h" |
55 | #if defined(HAVE_GETRUSAGE) |
56 | # include <sys/resource.h> |
57 | #elif defined(HAVE_VTIMES) |
58 | # include <sys/vtimes.h> |
59 | #endif |
60 | |
61 | #include <sys/wait.h> |
62 | |
63 | #include <fcntl.h> |
64 | #include <unistd.h> |
65 | |
66 | /* --- Local headers --- */ |
67 | |
68 | #include "noise.h" |
69 | #include "rand.h" |
70 | #include "utils.h" |
71 | |
72 | /*----- Main code ---------------------------------------------------------*/ |
73 | |
74 | /* --- @noise__shell@ --- * |
75 | * |
76 | * Arguments: @const char *cmd@ = pointer to a shell command |
77 | * |
78 | * Returns: --- |
79 | * |
80 | * Use: Adds the output of the shell command to the randomness pool. |
81 | * Some care is taken to do the Right Thing when running setuid. |
82 | */ |
83 | |
84 | static void noise__shell(const char *cmd) |
85 | { |
86 | int pfd[2]; |
87 | pid_t pid; |
88 | |
89 | /* --- Create a pipe for talking to the child --- */ |
90 | |
91 | if (pipe(pfd)) |
92 | return; |
93 | |
94 | /* --- Create the child process --- */ |
95 | |
96 | pid = fork(); |
97 | if (pid < 0) |
98 | return; |
99 | |
100 | if (pid == 0) { |
101 | int fd; |
102 | char *argv[] = { "/bin/sh", "-c", 0, 0 }; |
103 | char *env[] = { |
104 | "PATH=/bin:/usr/bin:/usr/ucb:/usr/etc:/sbin:/usr/sbin", |
105 | 0 |
106 | }; |
107 | |
108 | /* --- Become whoever I'm being run as --- */ |
109 | |
110 | setuid(getuid()); |
111 | |
112 | /* --- Close the old standard streams --- */ |
113 | |
114 | close(0); |
115 | close(1); |
116 | close(2); |
117 | |
118 | /* --- Set up stdin and stderr to be empty, and stdout as our pipe --- */ |
119 | |
120 | if (((fd = open("/dev/null", O_RDONLY)) != 0 && |
121 | (fd = dup2(fd, 0)) != 0) || |
122 | ((fd = dup2(pfd[1], 1)) != 1) || |
123 | ((fd = open("/dev/null", O_WRONLY)) != 2 && |
124 | (fd = dup2(fd, 2)) != 2)) |
125 | goto child_fail; |
126 | |
127 | /* --- Close the original pipe file descriptors --- */ |
128 | |
129 | close(pfd[0]); |
130 | close(pfd[1]); |
131 | burn(pfd); |
132 | |
133 | /* --- Now run the child process --- */ |
134 | |
135 | argv[2] = (char *)cmd; /* POSIX screwed up the prototype */ |
136 | execve("/bin/sh", argv, env); |
137 | |
138 | /* --- Something went horribly wrong --- */ |
139 | |
140 | child_fail: |
141 | _exit(127); |
142 | } |
143 | |
144 | /* --- Now read from the child until it's all done --- */ |
145 | |
146 | { |
147 | char buf[1024]; |
148 | ssize_t sz; |
149 | |
150 | close(pfd[1]); |
151 | for (;;) { |
152 | sz = read(pfd[0], buf, sizeof(buf)); |
153 | if (sz == 0 || (sz < 0 && sz != EINTR)) |
154 | break; |
155 | rand_add(buf, sz); |
156 | } |
157 | close(pfd[0]); |
158 | rand_add(pfd, sizeof(pfd)); |
159 | burn(buf); burn(pfd); |
160 | } |
161 | |
162 | /* --- The child should be dead now, so wait for it --- */ |
163 | |
164 | { |
165 | int st; |
166 | |
167 | wait(&st); |
168 | rand_add(&st, sizeof(st)); |
169 | rand_add(&pid, sizeof(pid)); |
170 | } |
171 | } |
172 | |
173 | /* --- @noise_acquire@ --- * |
174 | * |
175 | * Arguments: --- |
176 | * |
177 | * Returns: --- |
178 | * |
179 | * Use: Attempts to acquire an amount of random noise from the |
180 | * environment. A lot of it's not actually much good, but |
181 | * it's better than nothing. There's probably a bit or two's |
182 | * worth in each item which gets added. |
183 | */ |
184 | |
185 | void noise_acquire(void) |
186 | { |
187 | /* --- Try a real random number source --- * |
188 | * |
189 | * Some operating systems (notably Linux) provide a `/dev/random' which |
190 | * contains distilled random numbers from the outside world. |
191 | */ |
192 | |
193 | { |
194 | int fd; |
195 | int f; |
196 | unsigned char buff[64]; |
197 | ssize_t sz; |
198 | |
199 | if ((fd = open("/dev/random", O_RDONLY) >= 0) && |
200 | (f = fcntl(fd, F_GETFL, 0)) >= 0 && |
201 | fcntl(fd, F_SETFL, f | O_NONBLOCK) >= 0 && |
202 | (sz = read(fd, buff, sizeof(buff))) > 0) { |
203 | rand_add(buff, sz); |
204 | burn(buff); |
205 | } |
206 | if (fd >= 0) |
207 | close(fd); |
208 | } |
209 | |
210 | /* --- Squeeze some entropy from the current time --- */ |
211 | |
212 | { |
213 | struct timeval tv; |
214 | clock_t c; |
215 | |
216 | gettimeofday(&tv, 0); |
217 | c = clock(); |
218 | rand_add(&tv, sizeof(tv)); |
219 | rand_add(&c, sizeof(c)); |
220 | burn(tv); burn(c); |
221 | } |
222 | |
223 | /* --- Try some commands which ask the outside world some questions --- */ |
224 | |
225 | noise__shell("ps auxww"); |
226 | noise__shell("ps -ef"); |
227 | noise__shell("df"); |
228 | /* @noise__shell("netstat -a");@ -- takes too long */ |
229 | |
230 | /* --- Get our resource usage to see if that's at all interesting --- */ |
231 | |
232 | #if defined(HAVE_GETRUSAGE) |
233 | { |
234 | struct rusage ru; |
235 | getrusage(RUSAGE_SELF, &ru); |
236 | rand_add(&ru, sizeof(ru)); |
237 | getrusage(RUSAGE_CHILDREN, &ru); |
238 | rand_add(&ru, sizeof(ru)); |
239 | burn(ru); |
240 | } |
241 | #elif defined(HAVE_VTIMES) |
242 | { |
243 | struct vtimes vt, vtc; |
244 | vtimes(&vt, &vtc); |
245 | rand_add(&vt, sizeof(vt)); |
246 | rand_add(&vtc, sizeof(vtc)); |
247 | burn(vt); burn(vtc); |
248 | } |
249 | #endif |
250 | |
251 | /* --- Squeeze some more entropy from the current time --- */ |
252 | |
253 | { |
254 | struct timeval tv; |
255 | clock_t c; |
256 | |
257 | gettimeofday(&tv, 0); |
258 | c = clock(); |
259 | rand_add(&tv, sizeof(tv)); |
260 | rand_add(&c, sizeof(c)); |
261 | burn(tv); burn(c); |
262 | } |
263 | |
264 | /* --- Done -- churn the random pool --- */ |
265 | |
266 | rand_churn(); |
267 | } |
268 | |
269 | /*----- That's all, folks -------------------------------------------------*/ |