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bfc9a610 | 1 | /* |
2 | * Copyright (c) 2000 Damien Miller. All rights reserved. | |
3 | * | |
4 | * Redistribution and use in source and binary forms, with or without | |
5 | * modification, are permitted provided that the following conditions | |
6 | * are met: | |
7 | * 1. Redistributions of source code must retain the above copyright | |
8 | * notice, this list of conditions and the following disclaimer. | |
9 | * 2. Redistributions in binary form must reproduce the above copyright | |
10 | * notice, this list of conditions and the following disclaimer in the | |
11 | * documentation and/or other materials provided with the distribution. | |
12 | * 3. All advertising materials mentioning features or use of this software | |
13 | * must display the following acknowledgement: | |
14 | * This product includes software developed by Markus Friedl. | |
15 | * 4. The name of the author may not be used to endorse or promote products | |
16 | * derived from this software without specific prior written permission. | |
17 | * | |
18 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR | |
19 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES | |
20 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. | |
21 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, | |
22 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT | |
23 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | |
24 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | |
25 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
26 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF | |
27 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
28 | */ | |
29 | ||
30 | #include "includes.h" | |
31 | ||
32 | #include "ssh.h" | |
33 | #include "xmalloc.h" | |
34 | ||
35484284 | 35 | #include <openssl/rand.h> |
36 | #include <openssl/sha.h> | |
bfc9a610 | 37 | |
38 | RCSID("$Id$"); | |
39 | ||
bfc9a610 | 40 | #ifndef offsetof |
41 | # define offsetof(type, member) ((size_t) &((type *)0)->member) | |
42 | #endif | |
48c99b2c | 43 | |
44 | /* Print lots of detail */ | |
45 | /* #define DEBUG_ENTROPY */ | |
46 | ||
47 | /* Number of times to pass through command list gathering entropy */ | |
48 | #define NUM_ENTROPY_RUNS 1 | |
49 | ||
50 | /* Scale entropy estimates back by this amount on subsequent runs */ | |
51 | #define SCALE_PER_RUN 10.0 | |
52 | ||
53 | /* Minimum number of commands to be considered valid */ | |
54 | #define MIN_ENTROPY_SOURCES 16 | |
55 | ||
56 | #define WHITESPACE " \t\n" | |
57 | ||
cbd7492e | 58 | #ifndef RUSAGE_SELF |
59 | # define RUSAGE_SELF 0 | |
60 | #endif | |
61 | #ifndef RUSAGE_CHILDREN | |
62 | # define RUSAGE_CHILDREN 0 | |
63 | #endif | |
64 | ||
48c99b2c | 65 | #if defined(EGD_SOCKET) || defined(RANDOM_POOL) |
66 | ||
67 | #ifdef EGD_SOCKET | |
bfc9a610 | 68 | /* Collect entropy from EGD */ |
be0b9bb7 | 69 | int get_random_bytes(unsigned char *buf, int len) |
bfc9a610 | 70 | { |
be0b9bb7 | 71 | int fd; |
72 | char msg[2]; | |
bfc9a610 | 73 | struct sockaddr_un addr; |
74 | int addr_len; | |
75 | ||
be0b9bb7 | 76 | /* Sanity checks */ |
bfc9a610 | 77 | if (sizeof(EGD_SOCKET) > sizeof(addr.sun_path)) |
78 | fatal("Random pool path is too long"); | |
be0b9bb7 | 79 | if (len > 255) |
80 | fatal("Too many bytes to read from EGD"); | |
81 | ||
82 | memset(&addr, '\0', sizeof(addr)); | |
83 | addr.sun_family = AF_UNIX; | |
48c99b2c | 84 | strlcpy(addr.sun_path, EGD_SOCKET, sizeof(addr.sun_path)); |
bfc9a610 | 85 | addr_len = offsetof(struct sockaddr_un, sun_path) + sizeof(EGD_SOCKET); |
86 | ||
be0b9bb7 | 87 | fd = socket(AF_UNIX, SOCK_STREAM, 0); |
88 | if (fd == -1) { | |
89 | error("Couldn't create AF_UNIX socket: %s", strerror(errno)); | |
90 | return(0); | |
91 | } | |
bfc9a610 | 92 | |
be0b9bb7 | 93 | if (connect(fd, (struct sockaddr*)&addr, addr_len) == -1) { |
94 | error("Couldn't connect to EGD socket \"%s\": %s", | |
95 | addr.sun_path, strerror(errno)); | |
96 | close(fd); | |
97 | return(0); | |
98 | } | |
bfc9a610 | 99 | |
be0b9bb7 | 100 | /* Send blocking read request to EGD */ |
101 | msg[0] = 0x02; | |
102 | msg[1] = len; | |
103 | ||
104 | if (atomicio(write, fd, msg, sizeof(msg)) != sizeof(msg)) { | |
105 | error("Couldn't write to EGD socket \"%s\": %s", | |
106 | EGD_SOCKET, strerror(errno)); | |
107 | close(fd); | |
108 | return(0); | |
109 | } | |
bfc9a610 | 110 | |
be0b9bb7 | 111 | if (atomicio(read, fd, buf, len) != len) { |
112 | error("Couldn't read from EGD socket \"%s\": %s", | |
113 | EGD_SOCKET, strerror(errno)); | |
114 | close(fd); | |
115 | return(0); | |
116 | } | |
117 | ||
118 | close(fd); | |
119 | ||
120 | return(1); | |
bfc9a610 | 121 | } |
122 | #else /* !EGD_SOCKET */ | |
123 | #ifdef RANDOM_POOL | |
124 | /* Collect entropy from /dev/urandom or pipe */ | |
be0b9bb7 | 125 | int get_random_bytes(unsigned char *buf, int len) |
bfc9a610 | 126 | { |
be0b9bb7 | 127 | int random_pool; |
bfc9a610 | 128 | |
be0b9bb7 | 129 | random_pool = open(RANDOM_POOL, O_RDONLY); |
bfc9a610 | 130 | if (random_pool == -1) { |
be0b9bb7 | 131 | error("Couldn't open random pool \"%s\": %s", |
132 | RANDOM_POOL, strerror(errno)); | |
133 | return(0); | |
bfc9a610 | 134 | } |
135 | ||
be0b9bb7 | 136 | if (atomicio(read, random_pool, buf, len) != len) { |
137 | error("Couldn't read from random pool \"%s\": %s", | |
138 | RANDOM_POOL, strerror(errno)); | |
139 | close(random_pool); | |
140 | return(0); | |
141 | } | |
142 | ||
143 | close(random_pool); | |
144 | ||
145 | return(1); | |
bfc9a610 | 146 | } |
147 | #endif /* RANDOM_POOL */ | |
148 | #endif /* EGD_SOCKET */ | |
149 | ||
48c99b2c | 150 | /* |
151 | * Seed OpenSSL's random number pool from Kernel random number generator | |
152 | * or EGD | |
153 | */ | |
154 | void | |
155 | seed_rng(void) | |
156 | { | |
157 | char buf[32]; | |
158 | ||
159 | debug("Seeding random number generator"); | |
be0b9bb7 | 160 | |
161 | if (!get_random_bytes(buf, sizeof(buf)) && !RAND_status()) | |
162 | fatal("Entropy collection failed and entropy exhausted"); | |
163 | ||
48c99b2c | 164 | RAND_add(buf, sizeof(buf), sizeof(buf)); |
be0b9bb7 | 165 | |
48c99b2c | 166 | memset(buf, '\0', sizeof(buf)); |
167 | } | |
168 | ||
169 | #else /* defined(EGD_SOCKET) || defined(RANDOM_POOL) */ | |
170 | ||
bfc9a610 | 171 | /* |
172 | * FIXME: proper entropy estimations. All current values are guesses | |
b7a87eea | 173 | * FIXME: (ATL) do estimates at compile time? |
bfc9a610 | 174 | * FIXME: More entropy sources |
175 | */ | |
176 | ||
b7a87eea | 177 | /* slow command timeouts (all in milliseconds) */ |
178 | /* static int entropy_timeout_default = ENTROPY_TIMEOUT_MSEC; */ | |
179 | static int entropy_timeout_current = ENTROPY_TIMEOUT_MSEC; | |
180 | ||
181 | static int prng_seed_loaded = 0; | |
d3083fbd | 182 | static int prng_seed_saved = 0; |
183 | static int prng_commands_loaded = 0; | |
bfc9a610 | 184 | |
185 | typedef struct | |
186 | { | |
187 | /* Proportion of data that is entropy */ | |
188 | double rate; | |
b7a87eea | 189 | /* Counter goes positive if this command times out */ |
190 | unsigned int badness; | |
191 | /* Increases by factor of two each timeout */ | |
192 | unsigned int sticky_badness; | |
bfc9a610 | 193 | /* Path to executable */ |
d3083fbd | 194 | char *path; |
bfc9a610 | 195 | /* argv to pass to executable */ |
d3083fbd | 196 | char *args[5]; |
ad85db64 | 197 | /* full command string (debug) */ |
198 | char *cmdstring; | |
bfc9a610 | 199 | } entropy_source_t; |
200 | ||
b7a87eea | 201 | double stir_from_system(void); |
202 | double stir_from_programs(void); | |
203 | double stir_gettimeofday(double entropy_estimate); | |
204 | double stir_clock(double entropy_estimate); | |
205 | double stir_rusage(int who, double entropy_estimate); | |
206 | double hash_output_from_command(entropy_source_t *src, char *hash); | |
207 | ||
d3083fbd | 208 | /* this is initialised from a file, by prng_read_commands() */ |
209 | entropy_source_t *entropy_sources = NULL; | |
bfc9a610 | 210 | |
bfc9a610 | 211 | double |
212 | stir_from_system(void) | |
213 | { | |
214 | double total_entropy_estimate; | |
215 | long int i; | |
216 | ||
217 | total_entropy_estimate = 0; | |
218 | ||
219 | i = getpid(); | |
cbd7492e | 220 | RAND_add(&i, sizeof(i), 0.5); |
bfc9a610 | 221 | total_entropy_estimate += 0.1; |
222 | ||
223 | i = getppid(); | |
cbd7492e | 224 | RAND_add(&i, sizeof(i), 0.5); |
bfc9a610 | 225 | total_entropy_estimate += 0.1; |
226 | ||
227 | i = getuid(); | |
228 | RAND_add(&i, sizeof(i), 0.0); | |
229 | i = getgid(); | |
230 | RAND_add(&i, sizeof(i), 0.0); | |
231 | ||
232 | total_entropy_estimate += stir_gettimeofday(1.0); | |
cbd7492e | 233 | total_entropy_estimate += stir_clock(0.5); |
bfc9a610 | 234 | total_entropy_estimate += stir_rusage(RUSAGE_SELF, 2.0); |
235 | ||
236 | return(total_entropy_estimate); | |
237 | } | |
238 | ||
239 | double | |
240 | stir_from_programs(void) | |
241 | { | |
242 | int i; | |
243 | int c; | |
244 | double entropy_estimate; | |
245 | double total_entropy_estimate; | |
246 | char hash[SHA_DIGEST_LENGTH]; | |
247 | ||
bfc9a610 | 248 | total_entropy_estimate = 0; |
48c99b2c | 249 | for(i = 0; i < NUM_ENTROPY_RUNS; i++) { |
bfc9a610 | 250 | c = 0; |
251 | while (entropy_sources[c].path != NULL) { | |
bfc9a610 | 252 | |
b7a87eea | 253 | if (!entropy_sources[c].badness) { |
254 | /* Hash output from command */ | |
255 | entropy_estimate = hash_output_from_command(&entropy_sources[c], hash); | |
256 | ||
257 | /* Scale back entropy estimate according to command's rate */ | |
258 | entropy_estimate *= entropy_sources[c].rate; | |
bfc9a610 | 259 | |
b7a87eea | 260 | /* Upper bound of entropy estimate is SHA_DIGEST_LENGTH */ |
261 | if (entropy_estimate > SHA_DIGEST_LENGTH) | |
262 | entropy_estimate = SHA_DIGEST_LENGTH; | |
bfc9a610 | 263 | |
48c99b2c | 264 | /* Scale back estimates for subsequent passes through list */ |
265 | entropy_estimate /= SCALE_PER_RUN * (i + 1.0); | |
bfc9a610 | 266 | |
b7a87eea | 267 | /* Stir it in */ |
268 | RAND_add(hash, sizeof(hash), entropy_estimate); | |
bfc9a610 | 269 | |
48c99b2c | 270 | #ifdef DEBUG_ENTROPY |
ad85db64 | 271 | debug("Got %0.2f bytes of entropy from '%s'", entropy_estimate, |
272 | entropy_sources[c].cmdstring); | |
bfc9a610 | 273 | #endif |
274 | ||
b7a87eea | 275 | total_entropy_estimate += entropy_estimate; |
bfc9a610 | 276 | |
277 | /* Execution times should be a little unpredictable */ | |
b7a87eea | 278 | total_entropy_estimate += stir_gettimeofday(0.05); |
279 | total_entropy_estimate += stir_clock(0.05); | |
280 | total_entropy_estimate += stir_rusage(RUSAGE_SELF, 0.1); | |
281 | total_entropy_estimate += stir_rusage(RUSAGE_CHILDREN, 0.1); | |
282 | } else { | |
48c99b2c | 283 | #ifdef DEBUG_ENTROPY |
ad85db64 | 284 | debug("Command '%s' disabled (badness %d)", |
285 | entropy_sources[c].cmdstring, entropy_sources[c].badness); | |
b7a87eea | 286 | #endif |
287 | ||
288 | if (entropy_sources[c].badness > 0) | |
289 | entropy_sources[c].badness--; | |
290 | } | |
291 | ||
bfc9a610 | 292 | c++; |
293 | } | |
294 | } | |
295 | ||
296 | return(total_entropy_estimate); | |
297 | } | |
298 | ||
299 | double | |
300 | stir_gettimeofday(double entropy_estimate) | |
301 | { | |
302 | struct timeval tv; | |
303 | ||
304 | if (gettimeofday(&tv, NULL) == -1) | |
305 | fatal("Couldn't gettimeofday: %s", strerror(errno)); | |
306 | ||
307 | RAND_add(&tv, sizeof(tv), entropy_estimate); | |
308 | ||
309 | return(entropy_estimate); | |
310 | } | |
311 | ||
312 | double | |
313 | stir_clock(double entropy_estimate) | |
314 | { | |
315 | #ifdef HAVE_CLOCK | |
316 | clock_t c; | |
317 | ||
318 | c = clock(); | |
319 | RAND_add(&c, sizeof(c), entropy_estimate); | |
320 | ||
321 | return(entropy_estimate); | |
322 | #else /* _HAVE_CLOCK */ | |
323 | return(0); | |
324 | #endif /* _HAVE_CLOCK */ | |
325 | } | |
326 | ||
327 | double | |
328 | stir_rusage(int who, double entropy_estimate) | |
329 | { | |
330 | #ifdef HAVE_GETRUSAGE | |
331 | struct rusage ru; | |
332 | ||
b7a87eea | 333 | if (getrusage(who, &ru) == -1) |
cbd7492e | 334 | return(0); |
bfc9a610 | 335 | |
cbd7492e | 336 | RAND_add(&ru, sizeof(ru), entropy_estimate); |
bfc9a610 | 337 | |
338 | return(entropy_estimate); | |
339 | #else /* _HAVE_GETRUSAGE */ | |
340 | return(0); | |
341 | #endif /* _HAVE_GETRUSAGE */ | |
342 | } | |
343 | ||
ad85db64 | 344 | |
345 | static | |
346 | int | |
347 | _get_timeval_msec_difference(struct timeval *t1, struct timeval *t2) { | |
348 | int secdiff, usecdiff; | |
349 | ||
350 | secdiff = t2->tv_sec - t1->tv_sec; | |
351 | usecdiff = (secdiff*1000000) + (t2->tv_usec - t1->tv_usec); | |
352 | return (int)(usecdiff / 1000); | |
353 | } | |
354 | ||
bfc9a610 | 355 | double |
b7a87eea | 356 | hash_output_from_command(entropy_source_t *src, char *hash) |
bfc9a610 | 357 | { |
358 | static int devnull = -1; | |
359 | int p[2]; | |
b7a87eea | 360 | fd_set rdset; |
361 | int cmd_eof = 0, error_abort = 0; | |
ad85db64 | 362 | struct timeval tv_start, tv_current; |
363 | int msec_elapsed = 0; | |
bfc9a610 | 364 | pid_t pid; |
365 | int status; | |
ad85db64 | 366 | char buf[16384]; |
bfc9a610 | 367 | int bytes_read; |
368 | int total_bytes_read; | |
369 | SHA_CTX sha; | |
370 | ||
371 | if (devnull == -1) { | |
372 | devnull = open("/dev/null", O_RDWR); | |
373 | if (devnull == -1) | |
374 | fatal("Couldn't open /dev/null: %s", strerror(errno)); | |
375 | } | |
376 | ||
377 | if (pipe(p) == -1) | |
378 | fatal("Couldn't open pipe: %s", strerror(errno)); | |
379 | ||
ad85db64 | 380 | (void)gettimeofday(&tv_start, NULL); /* record start time */ |
381 | ||
bfc9a610 | 382 | switch (pid = fork()) { |
383 | case -1: /* Error */ | |
384 | close(p[0]); | |
385 | close(p[1]); | |
386 | fatal("Couldn't fork: %s", strerror(errno)); | |
387 | /* NOTREACHED */ | |
388 | case 0: /* Child */ | |
b7a87eea | 389 | dup2(devnull, STDIN_FILENO); |
390 | dup2(p[1], STDOUT_FILENO); | |
391 | dup2(p[1], STDERR_FILENO); | |
bfc9a610 | 392 | close(p[0]); |
393 | close(p[1]); | |
394 | close(devnull); | |
395 | ||
b7a87eea | 396 | execv(src->path, (char**)(src->args)); |
ad85db64 | 397 | debug("(child) Couldn't exec '%s': %s", src->cmdstring, |
398 | strerror(errno)); | |
b7a87eea | 399 | src->badness = src->sticky_badness = 128; |
bfc9a610 | 400 | _exit(-1); |
401 | default: /* Parent */ | |
402 | break; | |
403 | } | |
404 | ||
405 | RAND_add(&pid, sizeof(&pid), 0.0); | |
406 | ||
407 | close(p[1]); | |
408 | ||
409 | /* Hash output from child */ | |
410 | SHA1_Init(&sha); | |
411 | total_bytes_read = 0; | |
b7a87eea | 412 | |
413 | while (!error_abort && !cmd_eof) { | |
414 | int ret; | |
415 | struct timeval tv; | |
ad85db64 | 416 | int msec_remaining; |
417 | ||
418 | (void) gettimeofday(&tv_current, 0); | |
48c99b2c | 419 | msec_elapsed = _get_timeval_msec_difference(&tv_start, &tv_current); |
ad85db64 | 420 | if (msec_elapsed >= entropy_timeout_current) { |
421 | error_abort=1; | |
422 | continue; | |
423 | } | |
424 | msec_remaining = entropy_timeout_current - msec_elapsed; | |
b7a87eea | 425 | |
426 | FD_ZERO(&rdset); | |
427 | FD_SET(p[0], &rdset); | |
ad85db64 | 428 | tv.tv_sec = msec_remaining / 1000; |
429 | tv.tv_usec = (msec_remaining % 1000) * 1000; | |
b7a87eea | 430 | |
431 | ret = select(p[0]+1, &rdset, NULL, NULL, &tv); | |
ad85db64 | 432 | |
b7a87eea | 433 | switch (ret) { |
434 | case 0: | |
435 | /* timer expired */ | |
436 | error_abort = 1; | |
437 | break; | |
438 | ||
439 | case 1: | |
440 | /* command input */ | |
441 | bytes_read = read(p[0], buf, sizeof(buf)); | |
442 | if (bytes_read == -1) { | |
443 | error_abort = 1; | |
444 | break; | |
445 | } | |
ad85db64 | 446 | if (bytes_read) { |
447 | SHA1_Update(&sha, buf, bytes_read); | |
448 | total_bytes_read += bytes_read; | |
449 | RAND_add(&bytes_read, sizeof(&bytes_read), 0.0); | |
450 | } else | |
451 | cmd_eof = 1; | |
b7a87eea | 452 | |
453 | break; | |
454 | ||
455 | case -1: | |
456 | default: | |
ad85db64 | 457 | debug("Command '%s': select() failed: %s", src->cmdstring, |
458 | strerror(errno)); | |
b7a87eea | 459 | error_abort = 1; |
460 | break; | |
461 | } /* switch ret */ | |
462 | ||
463 | RAND_add(&tv, sizeof(&tv), 0.0); | |
464 | } /* while !error_abort && !cmd_eof */ | |
465 | ||
bfc9a610 | 466 | SHA1_Final(hash, &sha); |
467 | ||
468 | close(p[0]); | |
ad85db64 | 469 | |
48c99b2c | 470 | #ifdef DEBUG_ENTROPY |
ad85db64 | 471 | debug("Time elapsed: %d msec", msec_elapsed); |
48c99b2c | 472 | #endif |
bfc9a610 | 473 | |
474 | if (waitpid(pid, &status, 0) == -1) { | |
ad85db64 | 475 | debug("Couldn't wait for child '%s' completion: %s", src->cmdstring, |
476 | strerror(errno)); | |
b7a87eea | 477 | return(0.0); |
bfc9a610 | 478 | } |
479 | ||
480 | RAND_add(&status, sizeof(&status), 0.0); | |
481 | ||
b7a87eea | 482 | if (error_abort) { |
483 | /* closing p[0] on timeout causes the entropy command to | |
484 | * SIGPIPE. Take whatever output we got, and mark this command | |
485 | * as slow */ | |
ad85db64 | 486 | debug("Command '%s' timed out", src->cmdstring); |
b7a87eea | 487 | src->sticky_badness *= 2; |
488 | src->badness = src->sticky_badness; | |
bfc9a610 | 489 | return(total_bytes_read); |
b7a87eea | 490 | } |
491 | ||
492 | if (WIFEXITED(status)) { | |
493 | if (WEXITSTATUS(status)==0) { | |
494 | return(total_bytes_read); | |
495 | } else { | |
48c99b2c | 496 | debug("Command '%s' exit status was %d", src->cmdstring, |
497 | WEXITSTATUS(status)); | |
b7a87eea | 498 | src->badness = src->sticky_badness = 128; |
499 | return (0.0); | |
500 | } | |
501 | } else if (WIFSIGNALED(status)) { | |
48c99b2c | 502 | debug("Command '%s' returned on uncaught signal %d !", src->cmdstring, |
503 | status); | |
b7a87eea | 504 | src->badness = src->sticky_badness = 128; |
505 | return(0.0); | |
506 | } else | |
507 | return(0.0); | |
508 | } | |
509 | ||
510 | /* | |
511 | * prng seedfile functions | |
512 | */ | |
513 | int | |
514 | prng_check_seedfile(char *filename) { | |
515 | ||
516 | struct stat st; | |
517 | ||
518 | /* FIXME raceable: eg replace seed between this stat and subsequent open */ | |
519 | /* Not such a problem because we don't trust the seed file anyway */ | |
520 | if (lstat(filename, &st) == -1) { | |
521 | /* Fail on hard errors */ | |
522 | if (errno != ENOENT) | |
523 | fatal("Couldn't stat random seed file \"%s\": %s", filename, | |
524 | strerror(errno)); | |
525 | ||
526 | return(0); | |
527 | } | |
528 | ||
529 | /* regular file? */ | |
530 | if (!S_ISREG(st.st_mode)) | |
531 | fatal("PRNG seedfile %.100s is not a regular file", filename); | |
532 | ||
533 | /* mode 0600, owned by root or the current user? */ | |
d02a3a00 | 534 | if (((st.st_mode & 0177) != 0) || !(st.st_uid == getuid())) |
b7a87eea | 535 | fatal("PRNG seedfile %.100s must be mode 0600, owned by uid %d", |
536 | filename, getuid()); | |
537 | ||
538 | return(1); | |
539 | } | |
540 | ||
541 | void | |
542 | prng_write_seedfile(void) { | |
543 | int fd; | |
544 | char seed[1024]; | |
545 | char filename[1024]; | |
546 | struct passwd *pw; | |
547 | ||
548 | /* Don't bother if we have already saved a seed */ | |
549 | if (prng_seed_saved) | |
550 | return; | |
551 | ||
52bcc044 | 552 | prng_seed_saved = 1; |
553 | ||
b7a87eea | 554 | pw = getpwuid(getuid()); |
555 | if (pw == NULL) | |
556 | fatal("Couldn't get password entry for current user (%i): %s", | |
557 | getuid(), strerror(errno)); | |
558 | ||
559 | /* Try to ensure that the parent directory is there */ | |
560 | snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir, | |
561 | SSH_USER_DIR); | |
562 | mkdir(filename, 0700); | |
563 | ||
564 | snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir, | |
565 | SSH_PRNG_SEED_FILE); | |
566 | ||
567 | debug("writing PRNG seed to file %.100s", filename); | |
568 | ||
569 | RAND_bytes(seed, sizeof(seed)); | |
570 | ||
571 | /* Don't care if the seed doesn't exist */ | |
572 | prng_check_seedfile(filename); | |
573 | ||
574 | if ((fd = open(filename, O_WRONLY|O_TRUNC|O_CREAT, 0600)) == -1) | |
575 | fatal("couldn't access PRNG seedfile %.100s (%.100s)", filename, | |
576 | strerror(errno)); | |
577 | ||
578 | if (atomicio(write, fd, &seed, sizeof(seed)) != sizeof(seed)) | |
579 | fatal("problem writing PRNG seedfile %.100s (%.100s)", filename, | |
580 | strerror(errno)); | |
581 | ||
582 | close(fd); | |
583 | } | |
584 | ||
585 | void | |
586 | prng_read_seedfile(void) { | |
587 | int fd; | |
588 | char seed[1024]; | |
589 | char filename[1024]; | |
590 | struct passwd *pw; | |
591 | ||
592 | pw = getpwuid(getuid()); | |
593 | if (pw == NULL) | |
594 | fatal("Couldn't get password entry for current user (%i): %s", | |
595 | getuid(), strerror(errno)); | |
596 | ||
597 | snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir, | |
598 | SSH_PRNG_SEED_FILE); | |
599 | ||
600 | debug("loading PRNG seed from file %.100s", filename); | |
601 | ||
602 | if (!prng_check_seedfile(filename)) { | |
603 | verbose("Random seed file not found, creating new"); | |
604 | prng_write_seedfile(); | |
605 | ||
606 | /* Reseed immediatly */ | |
607 | (void)stir_from_system(); | |
608 | (void)stir_from_programs(); | |
609 | return; | |
610 | } | |
611 | ||
612 | /* open the file and read in the seed */ | |
613 | fd = open(filename, O_RDONLY); | |
614 | if (fd == -1) | |
615 | fatal("could not open PRNG seedfile %.100s (%.100s)", filename, | |
616 | strerror(errno)); | |
617 | ||
618 | if (atomicio(read, fd, &seed, sizeof(seed)) != sizeof(seed)) { | |
619 | verbose("invalid or short read from PRNG seedfile %.100s - ignoring", | |
620 | filename); | |
621 | memset(seed, '\0', sizeof(seed)); | |
622 | } | |
623 | close(fd); | |
624 | ||
625 | /* stir in the seed, with estimated entropy zero */ | |
626 | RAND_add(&seed, sizeof(seed), 0.0); | |
bfc9a610 | 627 | } |
b7a87eea | 628 | |
d3083fbd | 629 | |
630 | /* | |
631 | * entropy command initialisation functions | |
632 | */ | |
d3083fbd | 633 | int |
634 | prng_read_commands(char *cmdfilename) | |
635 | { | |
636 | FILE *f; | |
d3083fbd | 637 | char *cp; |
48c99b2c | 638 | char line[1024]; |
639 | char cmd[1024]; | |
640 | char path[256]; | |
d3083fbd | 641 | int linenum; |
d3083fbd | 642 | int num_cmds = 64; |
643 | int cur_cmd = 0; | |
48c99b2c | 644 | double est; |
645 | entropy_source_t *entcmd; | |
d3083fbd | 646 | |
647 | f = fopen(cmdfilename, "r"); | |
648 | if (!f) { | |
649 | fatal("couldn't read entropy commands file %.100s: %.100s", | |
650 | cmdfilename, strerror(errno)); | |
651 | } | |
652 | ||
d3083fbd | 653 | entcmd = (entropy_source_t *)xmalloc(num_cmds * sizeof(entropy_source_t)); |
654 | memset(entcmd, '\0', num_cmds * sizeof(entropy_source_t)); | |
655 | ||
48c99b2c | 656 | /* Read in file */ |
657 | linenum = 0; | |
d3083fbd | 658 | while (fgets(line, sizeof(line), f)) { |
48c99b2c | 659 | int arg; |
660 | char *argv; | |
661 | ||
d3083fbd | 662 | linenum++; |
663 | ||
664 | /* skip leading whitespace, test for blank line or comment */ | |
665 | cp = line + strspn(line, WHITESPACE); | |
666 | if ((*cp == 0) || (*cp == '#')) | |
667 | continue; /* done with this line */ | |
668 | ||
48c99b2c | 669 | /* First non-whitespace char should be double quote delimiting */ |
670 | /* commandline */ | |
671 | if (*cp != '"') { | |
672 | error("bad entropy command, %.100s line %d", cmdfilename, | |
673 | linenum); | |
674 | continue; | |
675 | } | |
d3083fbd | 676 | |
48c99b2c | 677 | /* first token, command args (incl. argv[0]) in double quotes */ |
678 | cp = strtok(cp, "\""); | |
679 | if (cp == NULL) { | |
680 | error("missing or bad command string, %.100s line %d -- ignored", | |
681 | cmdfilename, linenum); | |
682 | continue; | |
683 | } | |
684 | strlcpy(cmd, cp, sizeof(cmd)); | |
685 | ||
686 | /* second token, full command path */ | |
687 | if ((cp = strtok(NULL, WHITESPACE)) == NULL) { | |
688 | error("missing command path, %.100s line %d -- ignored", | |
689 | cmdfilename, linenum); | |
690 | continue; | |
691 | } | |
d3083fbd | 692 | |
48c99b2c | 693 | /* did configure mark this as dead? */ |
694 | if (strncmp("undef", cp, 5) == 0) | |
695 | continue; | |
d3083fbd | 696 | |
48c99b2c | 697 | strlcpy(path, cp, sizeof(path)); |
698 | ||
699 | /* third token, entropy rate estimate for this command */ | |
700 | if ((cp = strtok(NULL, WHITESPACE)) == NULL) { | |
701 | error("missing entropy estimate, %.100s line %d -- ignored", | |
702 | cmdfilename, linenum); | |
703 | continue; | |
704 | } | |
705 | est = strtod(cp, &argv); | |
706 | ||
707 | /* end of line */ | |
708 | if ((cp = strtok(NULL, WHITESPACE)) != NULL) { | |
709 | error("garbage at end of line %d in %.100s -- ignored", linenum, | |
710 | cmdfilename); | |
d3083fbd | 711 | continue; |
712 | } | |
48c99b2c | 713 | |
714 | /* save the command for debug messages */ | |
715 | entcmd[cur_cmd].cmdstring = xstrdup(cmd); | |
716 | ||
717 | /* split the command args */ | |
718 | cp = strtok(cmd, WHITESPACE); | |
719 | arg = 0; | |
720 | argv = NULL; | |
721 | do { | |
722 | char *s = (char*)xmalloc(strlen(cp) + 1); | |
723 | strncpy(s, cp, strlen(cp) + 1); | |
724 | entcmd[cur_cmd].args[arg] = s; | |
725 | arg++; | |
726 | } while ((arg < 5) && (cp = strtok(NULL, WHITESPACE))); | |
727 | ||
728 | if (strtok(NULL, WHITESPACE)) | |
729 | error("ignored extra command elements (max 5), %.100s line %d", | |
730 | cmdfilename, linenum); | |
731 | ||
732 | /* Copy the command path and rate estimate */ | |
733 | entcmd[cur_cmd].path = xstrdup(path); | |
734 | entcmd[cur_cmd].rate = est; | |
735 | ||
736 | /* Initialise other values */ | |
737 | entcmd[cur_cmd].sticky_badness = 1; | |
738 | ||
739 | cur_cmd++; | |
740 | ||
741 | /* If we've filled the array, reallocate it twice the size */ | |
742 | /* Do this now because even if this we're on the last command, | |
743 | we need another slot to mark the last entry */ | |
744 | if (cur_cmd == num_cmds) { | |
745 | num_cmds *= 2; | |
746 | entcmd = xrealloc(entcmd, num_cmds * sizeof(entropy_source_t)); | |
747 | } | |
d3083fbd | 748 | } |
749 | ||
750 | /* zero the last entry */ | |
751 | memset(&entcmd[cur_cmd], '\0', sizeof(entropy_source_t)); | |
48c99b2c | 752 | |
d3083fbd | 753 | /* trim to size */ |
754 | entropy_sources = xrealloc(entcmd, (cur_cmd+1) * sizeof(entropy_source_t)); | |
755 | ||
756 | debug("loaded %d entropy commands from %.100s", cur_cmd, cmdfilename); | |
757 | ||
758 | return (cur_cmd >= MIN_ENTROPY_SOURCES); | |
759 | } | |
760 | ||
b7a87eea | 761 | /* |
762 | * Write a keyfile at exit | |
763 | */ | |
764 | void | |
765 | prng_seed_cleanup(void *junk) | |
766 | { | |
767 | prng_write_seedfile(); | |
768 | } | |
769 | ||
bfc9a610 | 770 | /* |
b7a87eea | 771 | * Conditionally Seed OpenSSL's random number pool from |
772 | * syscalls and program output | |
bfc9a610 | 773 | */ |
774 | void | |
775 | seed_rng(void) | |
776 | { | |
a64009ad | 777 | void *old_sigchld_handler; |
778 | ||
d3083fbd | 779 | if (!prng_commands_loaded) { |
780 | if (!prng_read_commands(SSH_PRNG_COMMAND_FILE)) | |
781 | fatal("PRNG initialisation failed -- exiting."); | |
782 | prng_commands_loaded = 1; | |
783 | } | |
784 | ||
a64009ad | 785 | /* Make sure some other sigchld handler doesn't reap our entropy */ |
786 | /* commands */ | |
787 | old_sigchld_handler = signal(SIGCHLD, SIG_DFL); | |
788 | ||
6c081128 | 789 | debug("Seeding random number generator."); |
790 | debug("OpenSSL random status is now %i\n", RAND_status()); | |
791 | debug("%i bytes from system calls", (int)stir_from_system()); | |
792 | debug("%i bytes from programs", (int)stir_from_programs()); | |
793 | debug("OpenSSL random status is now %i\n", RAND_status()); | |
b7a87eea | 794 | |
a64009ad | 795 | signal(SIGCHLD, old_sigchld_handler); |
796 | ||
ad85db64 | 797 | if (!RAND_status()) |
798 | fatal("Couldn't initialise builtin random number generator -- exiting."); | |
799 | ||
b7a87eea | 800 | if (!prng_seed_loaded) |
801 | { | |
802 | prng_seed_loaded = 1; | |
803 | prng_seed_saved = 0; | |
804 | prng_read_seedfile(); | |
805 | fatal_add_cleanup(prng_seed_cleanup, NULL); | |
806 | atexit(prng_write_seedfile); | |
807 | } | |
bfc9a610 | 808 | } |
809 | #endif /* defined(EGD_SOCKET) || defined(RANDOM_POOL) */ |