| 1 | /* -*-c-*- |
| 2 | * |
| 3 | * $Id: noise.c,v 1.6 1998/06/18 15:08:14 mdw Exp $ |
| 4 | * |
| 5 | * Collection of environmental noise |
| 6 | * |
| 7 | * (c) 1998 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 1.6 1998/06/18 15:08:14 mdw |
| 33 | * Improve signal handling when accumulating noise from child processes. |
| 34 | * |
| 35 | * Revision 1.5 1998/04/23 13:25:23 mdw |
| 36 | * Try to reduce the amount of `ps'ing done under OSF/1, because /dev/kmem |
| 37 | * seems very slow. |
| 38 | * |
| 39 | * Revision 1.4 1998/02/20 17:52:32 mdw |
| 40 | * Don't use `df' for noise gathering, because it gets upset when NFS |
| 41 | * servers aren't responding. |
| 42 | * |
| 43 | * Revision 1.3 1998/01/12 16:46:19 mdw |
| 44 | * Fix copyright date. |
| 45 | * |
| 46 | * Revision 1.2 1997/08/20 16:19:57 mdw |
| 47 | * Fix test for `/dev/random' so that it doesn't close `stdin' if it fails! |
| 48 | * |
| 49 | * Revision 1.1 1997/08/07 09:45:26 mdw |
| 50 | * New source file added to acquire environmental noise and add it to the |
| 51 | * randomness pool (see `rand.c'). |
| 52 | * |
| 53 | */ |
| 54 | |
| 55 | /*----- Header files ------------------------------------------------------*/ |
| 56 | |
| 57 | /* --- ANSI headers --- */ |
| 58 | |
| 59 | #include <ctype.h> |
| 60 | #include <errno.h> |
| 61 | #include <signal.h> |
| 62 | #include <stdio.h> |
| 63 | #include <stdlib.h> |
| 64 | #include <string.h> |
| 65 | #include <time.h> |
| 66 | |
| 67 | /* --- Unix headers --- */ |
| 68 | |
| 69 | #include <sys/types.h> |
| 70 | #include <sys/time.h> |
| 71 | |
| 72 | #include "config.h" |
| 73 | #if defined(HAVE_GETRUSAGE) |
| 74 | # include <sys/resource.h> |
| 75 | #elif defined(HAVE_VTIMES) |
| 76 | # include <sys/vtimes.h> |
| 77 | #endif |
| 78 | |
| 79 | #include <sys/wait.h> |
| 80 | |
| 81 | #include <fcntl.h> |
| 82 | #include <unistd.h> |
| 83 | |
| 84 | /* --- Local headers --- */ |
| 85 | |
| 86 | #include "noise.h" |
| 87 | #include "rand.h" |
| 88 | #include "utils.h" |
| 89 | |
| 90 | /*----- Main code ---------------------------------------------------------*/ |
| 91 | |
| 92 | /* --- @noise__shell@ --- * |
| 93 | * |
| 94 | * Arguments: @const char *cmd@ = pointer to a shell command |
| 95 | * |
| 96 | * Returns: --- |
| 97 | * |
| 98 | * Use: Adds the output of the shell command to the randomness pool. |
| 99 | * Some care is taken to do the Right Thing when running setuid. |
| 100 | */ |
| 101 | |
| 102 | static void noise__shell(const char *cmd) |
| 103 | { |
| 104 | int pfd[2]; |
| 105 | pid_t pid; |
| 106 | |
| 107 | #ifdef HAVE_SIGPROCMASK |
| 108 | sigset_t ob, nb; |
| 109 | #endif |
| 110 | |
| 111 | /* --- Create a pipe for talking to the child --- */ |
| 112 | |
| 113 | if (pipe(pfd)) |
| 114 | return; |
| 115 | |
| 116 | /* --- Sort out the signal handling for the parent --- * |
| 117 | * |
| 118 | * Block @SIGCHLD@ while this is going on. Unlike the standard @system@ |
| 119 | * function, I won't disable @SIGINT@ and @SIGQUIT@. Then, if the user |
| 120 | * stops the child with a terminal signal, the parent (i.e., me) gets |
| 121 | * killed too, and I don't end up with a tiny dribble of entropy when I'm |
| 122 | * expecting quite a lot. |
| 123 | */ |
| 124 | |
| 125 | #ifdef HAVE_SIGPROCMASK |
| 126 | sigemptyset(&nb); |
| 127 | sigaddset(&nb, SIGCHLD); |
| 128 | if (sigprocmask(SIG_BLOCK, &nb, &ob)) |
| 129 | goto fail_0; |
| 130 | #endif |
| 131 | |
| 132 | /* --- Create the child process --- */ |
| 133 | |
| 134 | pid = fork(); |
| 135 | if (pid < 0) |
| 136 | goto fail_1; |
| 137 | |
| 138 | if (pid == 0) { |
| 139 | int fd; |
| 140 | char *argv[] = { "/bin/sh", "-c", 0, 0 }; |
| 141 | char *env[] = { |
| 142 | "PATH=/bin:/usr/bin:/usr/ucb:/usr/etc:/sbin:/usr/sbin", |
| 143 | 0 |
| 144 | }; |
| 145 | |
| 146 | /* --- Restore signal handling things --- */ |
| 147 | |
| 148 | #ifdef HAVE_SIGPROCMASK |
| 149 | sigprocmask(SIG_SETMASK, &nb, 0); |
| 150 | #endif |
| 151 | |
| 152 | /* --- Become nobody --- * |
| 153 | * |
| 154 | * This assumes that @-2@ is a safe user to be. It shouldn't be root, |
| 155 | * because it doesn't need to be, and nothing should be done as root |
| 156 | * which could be done as someone else. It shouldn't be the user who |
| 157 | * invoked me, because that would enable her to kill the children before |
| 158 | * I've read enough entropy from them, and that wouldn't be good. |
| 159 | */ |
| 160 | |
| 161 | setuid(-2); |
| 162 | |
| 163 | /* --- Close the old standard streams --- */ |
| 164 | |
| 165 | close(0); |
| 166 | close(1); |
| 167 | close(2); |
| 168 | |
| 169 | /* --- Set up stdin and stderr to be empty, and stdout as our pipe --- */ |
| 170 | |
| 171 | if (((fd = open("/dev/null", O_RDONLY)) != 0 && |
| 172 | (fd = dup2(fd, 0)) != 0) || |
| 173 | ((fd = dup2(pfd[1], 1)) != 1) || |
| 174 | ((fd = open("/dev/null", O_WRONLY)) != 2 && |
| 175 | (fd = dup2(fd, 2)) != 2)) |
| 176 | goto child_fail; |
| 177 | |
| 178 | /* --- Close the original pipe file descriptors --- */ |
| 179 | |
| 180 | close(pfd[0]); |
| 181 | close(pfd[1]); |
| 182 | burn(pfd); |
| 183 | |
| 184 | /* --- Now run the child process --- */ |
| 185 | |
| 186 | argv[2] = (char *)cmd; /* POSIX screwed up the prototype */ |
| 187 | execve("/bin/sh", argv, env); |
| 188 | |
| 189 | /* --- Something went horribly wrong --- */ |
| 190 | |
| 191 | child_fail: |
| 192 | _exit(127); |
| 193 | } |
| 194 | |
| 195 | /* --- Now read from the child until it's all done --- */ |
| 196 | |
| 197 | { |
| 198 | char buf[1024]; |
| 199 | ssize_t sz; |
| 200 | |
| 201 | close(pfd[1]); |
| 202 | for (;;) { |
| 203 | sz = read(pfd[0], buf, sizeof(buf)); |
| 204 | if (sz == 0 || (sz < 0 && sz != EINTR)) |
| 205 | break; |
| 206 | rand_add(buf, sz); |
| 207 | } |
| 208 | close(pfd[0]); |
| 209 | rand_add(pfd, sizeof(pfd)); |
| 210 | burn(buf); burn(pfd); |
| 211 | } |
| 212 | |
| 213 | /* --- The child should be dead now, so wait for it --- */ |
| 214 | |
| 215 | { |
| 216 | int st; |
| 217 | wait(&st); |
| 218 | rand_add(&st, sizeof(st)); |
| 219 | rand_add(&pid, sizeof(pid)); |
| 220 | } |
| 221 | |
| 222 | /* --- Restore signals --- */ |
| 223 | |
| 224 | fail_1: |
| 225 | #ifdef HAVE_SIGPROCMASK |
| 226 | sigprocmask(SIG_SETMASK, &ob, 0); |
| 227 | #endif |
| 228 | fail_0:; |
| 229 | } |
| 230 | |
| 231 | /* --- @noise_acquire@ --- * |
| 232 | * |
| 233 | * Arguments: --- |
| 234 | * |
| 235 | * Returns: --- |
| 236 | * |
| 237 | * Use: Attempts to acquire an amount of random noise from the |
| 238 | * environment. A lot of it's not actually much good, but |
| 239 | * it's better than nothing. There's probably a bit or two's |
| 240 | * worth in each item which gets added. |
| 241 | */ |
| 242 | |
| 243 | void noise_acquire(void) |
| 244 | { |
| 245 | /* --- Try a real random number source --- * |
| 246 | * |
| 247 | * Some operating systems (notably Linux) provide a `/dev/random' which |
| 248 | * contains distilled random numbers from the outside world. |
| 249 | */ |
| 250 | |
| 251 | { |
| 252 | int fd; |
| 253 | int f; |
| 254 | unsigned char buff[64]; |
| 255 | ssize_t sz; |
| 256 | |
| 257 | if ((fd = open("/dev/random", O_RDONLY)) >= 0 && |
| 258 | (f = fcntl(fd, F_GETFL, 0)) >= 0 && |
| 259 | fcntl(fd, F_SETFL, f | O_NONBLOCK) >= 0 && |
| 260 | (sz = read(fd, buff, sizeof(buff))) > 0) { |
| 261 | rand_add(buff, sz); |
| 262 | burn(buff); |
| 263 | } |
| 264 | if (fd >= 0) |
| 265 | close(fd); |
| 266 | } |
| 267 | |
| 268 | /* --- Squeeze some entropy from the current time --- */ |
| 269 | |
| 270 | { |
| 271 | struct timeval tv; |
| 272 | clock_t c; |
| 273 | |
| 274 | gettimeofday(&tv, 0); |
| 275 | c = clock(); |
| 276 | rand_add(&tv, sizeof(tv)); |
| 277 | rand_add(&c, sizeof(c)); |
| 278 | burn(tv); burn(c); |
| 279 | } |
| 280 | |
| 281 | /* --- Try some commands which ask the outside world some questions --- */ |
| 282 | |
| 283 | noise__shell("ps auxww || ps -ef; netstat -an"); |
| 284 | |
| 285 | /* --- Get our resource usage to see if that's at all interesting --- */ |
| 286 | |
| 287 | #if defined(HAVE_GETRUSAGE) |
| 288 | { |
| 289 | struct rusage ru; |
| 290 | getrusage(RUSAGE_SELF, &ru); |
| 291 | rand_add(&ru, sizeof(ru)); |
| 292 | getrusage(RUSAGE_CHILDREN, &ru); |
| 293 | rand_add(&ru, sizeof(ru)); |
| 294 | burn(ru); |
| 295 | } |
| 296 | #elif defined(HAVE_VTIMES) |
| 297 | { |
| 298 | struct vtimes vt, vtc; |
| 299 | vtimes(&vt, &vtc); |
| 300 | rand_add(&vt, sizeof(vt)); |
| 301 | rand_add(&vtc, sizeof(vtc)); |
| 302 | burn(vt); burn(vtc); |
| 303 | } |
| 304 | #endif |
| 305 | |
| 306 | /* --- Squeeze some more entropy from the current time --- */ |
| 307 | |
| 308 | { |
| 309 | struct timeval tv; |
| 310 | clock_t c; |
| 311 | |
| 312 | gettimeofday(&tv, 0); |
| 313 | c = clock(); |
| 314 | rand_add(&tv, sizeof(tv)); |
| 315 | rand_add(&c, sizeof(c)); |
| 316 | burn(tv); burn(c); |
| 317 | } |
| 318 | |
| 319 | /* --- Done -- churn the random pool --- */ |
| 320 | |
| 321 | rand_churn(); |
| 322 | } |
| 323 | |
| 324 | /*----- That's all, folks -------------------------------------------------*/ |