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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 | |
b5b3f75d | 161 | if (!get_random_bytes(buf, sizeof(buf))) { |
162 | if (!RAND_status()) | |
163 | fatal("Entropy collection failed and entropy exhausted"); | |
164 | } else { | |
165 | RAND_add(buf, sizeof(buf), sizeof(buf)); | |
166 | } | |
167 | ||
48c99b2c | 168 | memset(buf, '\0', sizeof(buf)); |
169 | } | |
170 | ||
171 | #else /* defined(EGD_SOCKET) || defined(RANDOM_POOL) */ | |
172 | ||
bfc9a610 | 173 | /* |
174 | * FIXME: proper entropy estimations. All current values are guesses | |
b7a87eea | 175 | * FIXME: (ATL) do estimates at compile time? |
bfc9a610 | 176 | * FIXME: More entropy sources |
177 | */ | |
178 | ||
b7a87eea | 179 | /* slow command timeouts (all in milliseconds) */ |
180 | /* static int entropy_timeout_default = ENTROPY_TIMEOUT_MSEC; */ | |
181 | static int entropy_timeout_current = ENTROPY_TIMEOUT_MSEC; | |
182 | ||
183 | static int prng_seed_loaded = 0; | |
d3083fbd | 184 | static int prng_seed_saved = 0; |
185 | static int prng_commands_loaded = 0; | |
bfc9a610 | 186 | |
187 | typedef struct | |
188 | { | |
189 | /* Proportion of data that is entropy */ | |
190 | double rate; | |
b7a87eea | 191 | /* Counter goes positive if this command times out */ |
192 | unsigned int badness; | |
193 | /* Increases by factor of two each timeout */ | |
194 | unsigned int sticky_badness; | |
bfc9a610 | 195 | /* Path to executable */ |
d3083fbd | 196 | char *path; |
bfc9a610 | 197 | /* argv to pass to executable */ |
d3083fbd | 198 | char *args[5]; |
ad85db64 | 199 | /* full command string (debug) */ |
200 | char *cmdstring; | |
bfc9a610 | 201 | } entropy_source_t; |
202 | ||
b7a87eea | 203 | double stir_from_system(void); |
204 | double stir_from_programs(void); | |
205 | double stir_gettimeofday(double entropy_estimate); | |
206 | double stir_clock(double entropy_estimate); | |
207 | double stir_rusage(int who, double entropy_estimate); | |
208 | double hash_output_from_command(entropy_source_t *src, char *hash); | |
209 | ||
d3083fbd | 210 | /* this is initialised from a file, by prng_read_commands() */ |
211 | entropy_source_t *entropy_sources = NULL; | |
bfc9a610 | 212 | |
bfc9a610 | 213 | double |
214 | stir_from_system(void) | |
215 | { | |
216 | double total_entropy_estimate; | |
217 | long int i; | |
218 | ||
219 | total_entropy_estimate = 0; | |
220 | ||
221 | i = getpid(); | |
cbd7492e | 222 | RAND_add(&i, sizeof(i), 0.5); |
bfc9a610 | 223 | total_entropy_estimate += 0.1; |
224 | ||
225 | i = getppid(); | |
cbd7492e | 226 | RAND_add(&i, sizeof(i), 0.5); |
bfc9a610 | 227 | total_entropy_estimate += 0.1; |
228 | ||
229 | i = getuid(); | |
230 | RAND_add(&i, sizeof(i), 0.0); | |
231 | i = getgid(); | |
232 | RAND_add(&i, sizeof(i), 0.0); | |
233 | ||
234 | total_entropy_estimate += stir_gettimeofday(1.0); | |
cbd7492e | 235 | total_entropy_estimate += stir_clock(0.5); |
bfc9a610 | 236 | total_entropy_estimate += stir_rusage(RUSAGE_SELF, 2.0); |
237 | ||
238 | return(total_entropy_estimate); | |
239 | } | |
240 | ||
241 | double | |
242 | stir_from_programs(void) | |
243 | { | |
244 | int i; | |
245 | int c; | |
246 | double entropy_estimate; | |
247 | double total_entropy_estimate; | |
248 | char hash[SHA_DIGEST_LENGTH]; | |
249 | ||
bfc9a610 | 250 | total_entropy_estimate = 0; |
48c99b2c | 251 | for(i = 0; i < NUM_ENTROPY_RUNS; i++) { |
bfc9a610 | 252 | c = 0; |
253 | while (entropy_sources[c].path != NULL) { | |
bfc9a610 | 254 | |
b7a87eea | 255 | if (!entropy_sources[c].badness) { |
256 | /* Hash output from command */ | |
257 | entropy_estimate = hash_output_from_command(&entropy_sources[c], hash); | |
258 | ||
259 | /* Scale back entropy estimate according to command's rate */ | |
260 | entropy_estimate *= entropy_sources[c].rate; | |
bfc9a610 | 261 | |
b7a87eea | 262 | /* Upper bound of entropy estimate is SHA_DIGEST_LENGTH */ |
263 | if (entropy_estimate > SHA_DIGEST_LENGTH) | |
264 | entropy_estimate = SHA_DIGEST_LENGTH; | |
bfc9a610 | 265 | |
48c99b2c | 266 | /* Scale back estimates for subsequent passes through list */ |
267 | entropy_estimate /= SCALE_PER_RUN * (i + 1.0); | |
bfc9a610 | 268 | |
b7a87eea | 269 | /* Stir it in */ |
270 | RAND_add(hash, sizeof(hash), entropy_estimate); | |
bfc9a610 | 271 | |
48c99b2c | 272 | #ifdef DEBUG_ENTROPY |
ad85db64 | 273 | debug("Got %0.2f bytes of entropy from '%s'", entropy_estimate, |
274 | entropy_sources[c].cmdstring); | |
bfc9a610 | 275 | #endif |
276 | ||
b7a87eea | 277 | total_entropy_estimate += entropy_estimate; |
bfc9a610 | 278 | |
279 | /* Execution times should be a little unpredictable */ | |
b7a87eea | 280 | total_entropy_estimate += stir_gettimeofday(0.05); |
281 | total_entropy_estimate += stir_clock(0.05); | |
282 | total_entropy_estimate += stir_rusage(RUSAGE_SELF, 0.1); | |
283 | total_entropy_estimate += stir_rusage(RUSAGE_CHILDREN, 0.1); | |
284 | } else { | |
48c99b2c | 285 | #ifdef DEBUG_ENTROPY |
ad85db64 | 286 | debug("Command '%s' disabled (badness %d)", |
287 | entropy_sources[c].cmdstring, entropy_sources[c].badness); | |
b7a87eea | 288 | #endif |
289 | ||
290 | if (entropy_sources[c].badness > 0) | |
291 | entropy_sources[c].badness--; | |
292 | } | |
293 | ||
bfc9a610 | 294 | c++; |
295 | } | |
296 | } | |
297 | ||
298 | return(total_entropy_estimate); | |
299 | } | |
300 | ||
301 | double | |
302 | stir_gettimeofday(double entropy_estimate) | |
303 | { | |
304 | struct timeval tv; | |
305 | ||
306 | if (gettimeofday(&tv, NULL) == -1) | |
307 | fatal("Couldn't gettimeofday: %s", strerror(errno)); | |
308 | ||
309 | RAND_add(&tv, sizeof(tv), entropy_estimate); | |
310 | ||
311 | return(entropy_estimate); | |
312 | } | |
313 | ||
314 | double | |
315 | stir_clock(double entropy_estimate) | |
316 | { | |
317 | #ifdef HAVE_CLOCK | |
318 | clock_t c; | |
319 | ||
320 | c = clock(); | |
321 | RAND_add(&c, sizeof(c), entropy_estimate); | |
322 | ||
323 | return(entropy_estimate); | |
324 | #else /* _HAVE_CLOCK */ | |
325 | return(0); | |
326 | #endif /* _HAVE_CLOCK */ | |
327 | } | |
328 | ||
329 | double | |
330 | stir_rusage(int who, double entropy_estimate) | |
331 | { | |
332 | #ifdef HAVE_GETRUSAGE | |
333 | struct rusage ru; | |
334 | ||
b7a87eea | 335 | if (getrusage(who, &ru) == -1) |
cbd7492e | 336 | return(0); |
bfc9a610 | 337 | |
cbd7492e | 338 | RAND_add(&ru, sizeof(ru), entropy_estimate); |
bfc9a610 | 339 | |
340 | return(entropy_estimate); | |
341 | #else /* _HAVE_GETRUSAGE */ | |
342 | return(0); | |
343 | #endif /* _HAVE_GETRUSAGE */ | |
344 | } | |
345 | ||
ad85db64 | 346 | |
347 | static | |
348 | int | |
349 | _get_timeval_msec_difference(struct timeval *t1, struct timeval *t2) { | |
350 | int secdiff, usecdiff; | |
351 | ||
352 | secdiff = t2->tv_sec - t1->tv_sec; | |
353 | usecdiff = (secdiff*1000000) + (t2->tv_usec - t1->tv_usec); | |
354 | return (int)(usecdiff / 1000); | |
355 | } | |
356 | ||
bfc9a610 | 357 | double |
b7a87eea | 358 | hash_output_from_command(entropy_source_t *src, char *hash) |
bfc9a610 | 359 | { |
360 | static int devnull = -1; | |
361 | int p[2]; | |
b7a87eea | 362 | fd_set rdset; |
363 | int cmd_eof = 0, error_abort = 0; | |
ad85db64 | 364 | struct timeval tv_start, tv_current; |
365 | int msec_elapsed = 0; | |
bfc9a610 | 366 | pid_t pid; |
367 | int status; | |
ad85db64 | 368 | char buf[16384]; |
bfc9a610 | 369 | int bytes_read; |
370 | int total_bytes_read; | |
371 | SHA_CTX sha; | |
372 | ||
373 | if (devnull == -1) { | |
374 | devnull = open("/dev/null", O_RDWR); | |
375 | if (devnull == -1) | |
376 | fatal("Couldn't open /dev/null: %s", strerror(errno)); | |
377 | } | |
378 | ||
379 | if (pipe(p) == -1) | |
380 | fatal("Couldn't open pipe: %s", strerror(errno)); | |
381 | ||
ad85db64 | 382 | (void)gettimeofday(&tv_start, NULL); /* record start time */ |
383 | ||
bfc9a610 | 384 | switch (pid = fork()) { |
385 | case -1: /* Error */ | |
386 | close(p[0]); | |
387 | close(p[1]); | |
388 | fatal("Couldn't fork: %s", strerror(errno)); | |
389 | /* NOTREACHED */ | |
390 | case 0: /* Child */ | |
b7a87eea | 391 | dup2(devnull, STDIN_FILENO); |
392 | dup2(p[1], STDOUT_FILENO); | |
393 | dup2(p[1], STDERR_FILENO); | |
bfc9a610 | 394 | close(p[0]); |
395 | close(p[1]); | |
396 | close(devnull); | |
397 | ||
b7a87eea | 398 | execv(src->path, (char**)(src->args)); |
ad85db64 | 399 | debug("(child) Couldn't exec '%s': %s", src->cmdstring, |
400 | strerror(errno)); | |
b7a87eea | 401 | src->badness = src->sticky_badness = 128; |
bfc9a610 | 402 | _exit(-1); |
403 | default: /* Parent */ | |
404 | break; | |
405 | } | |
406 | ||
407 | RAND_add(&pid, sizeof(&pid), 0.0); | |
408 | ||
409 | close(p[1]); | |
410 | ||
411 | /* Hash output from child */ | |
412 | SHA1_Init(&sha); | |
413 | total_bytes_read = 0; | |
b7a87eea | 414 | |
415 | while (!error_abort && !cmd_eof) { | |
416 | int ret; | |
417 | struct timeval tv; | |
ad85db64 | 418 | int msec_remaining; |
419 | ||
420 | (void) gettimeofday(&tv_current, 0); | |
48c99b2c | 421 | msec_elapsed = _get_timeval_msec_difference(&tv_start, &tv_current); |
ad85db64 | 422 | if (msec_elapsed >= entropy_timeout_current) { |
423 | error_abort=1; | |
424 | continue; | |
425 | } | |
426 | msec_remaining = entropy_timeout_current - msec_elapsed; | |
b7a87eea | 427 | |
428 | FD_ZERO(&rdset); | |
429 | FD_SET(p[0], &rdset); | |
ad85db64 | 430 | tv.tv_sec = msec_remaining / 1000; |
431 | tv.tv_usec = (msec_remaining % 1000) * 1000; | |
b7a87eea | 432 | |
433 | ret = select(p[0]+1, &rdset, NULL, NULL, &tv); | |
ad85db64 | 434 | |
b7a87eea | 435 | switch (ret) { |
436 | case 0: | |
437 | /* timer expired */ | |
438 | error_abort = 1; | |
439 | break; | |
440 | ||
441 | case 1: | |
442 | /* command input */ | |
443 | bytes_read = read(p[0], buf, sizeof(buf)); | |
444 | if (bytes_read == -1) { | |
445 | error_abort = 1; | |
446 | break; | |
447 | } | |
ad85db64 | 448 | if (bytes_read) { |
449 | SHA1_Update(&sha, buf, bytes_read); | |
450 | total_bytes_read += bytes_read; | |
451 | RAND_add(&bytes_read, sizeof(&bytes_read), 0.0); | |
452 | } else | |
453 | cmd_eof = 1; | |
b7a87eea | 454 | |
455 | break; | |
456 | ||
457 | case -1: | |
458 | default: | |
ad85db64 | 459 | debug("Command '%s': select() failed: %s", src->cmdstring, |
460 | strerror(errno)); | |
b7a87eea | 461 | error_abort = 1; |
462 | break; | |
463 | } /* switch ret */ | |
464 | ||
465 | RAND_add(&tv, sizeof(&tv), 0.0); | |
466 | } /* while !error_abort && !cmd_eof */ | |
467 | ||
bfc9a610 | 468 | SHA1_Final(hash, &sha); |
469 | ||
470 | close(p[0]); | |
ad85db64 | 471 | |
48c99b2c | 472 | #ifdef DEBUG_ENTROPY |
ad85db64 | 473 | debug("Time elapsed: %d msec", msec_elapsed); |
48c99b2c | 474 | #endif |
bfc9a610 | 475 | |
476 | if (waitpid(pid, &status, 0) == -1) { | |
ad85db64 | 477 | debug("Couldn't wait for child '%s' completion: %s", src->cmdstring, |
478 | strerror(errno)); | |
b7a87eea | 479 | return(0.0); |
bfc9a610 | 480 | } |
481 | ||
482 | RAND_add(&status, sizeof(&status), 0.0); | |
483 | ||
b7a87eea | 484 | if (error_abort) { |
485 | /* closing p[0] on timeout causes the entropy command to | |
486 | * SIGPIPE. Take whatever output we got, and mark this command | |
487 | * as slow */ | |
ad85db64 | 488 | debug("Command '%s' timed out", src->cmdstring); |
b7a87eea | 489 | src->sticky_badness *= 2; |
490 | src->badness = src->sticky_badness; | |
bfc9a610 | 491 | return(total_bytes_read); |
b7a87eea | 492 | } |
493 | ||
494 | if (WIFEXITED(status)) { | |
495 | if (WEXITSTATUS(status)==0) { | |
496 | return(total_bytes_read); | |
497 | } else { | |
48c99b2c | 498 | debug("Command '%s' exit status was %d", src->cmdstring, |
499 | WEXITSTATUS(status)); | |
b7a87eea | 500 | src->badness = src->sticky_badness = 128; |
501 | return (0.0); | |
502 | } | |
503 | } else if (WIFSIGNALED(status)) { | |
48c99b2c | 504 | debug("Command '%s' returned on uncaught signal %d !", src->cmdstring, |
505 | status); | |
b7a87eea | 506 | src->badness = src->sticky_badness = 128; |
507 | return(0.0); | |
508 | } else | |
509 | return(0.0); | |
510 | } | |
511 | ||
512 | /* | |
513 | * prng seedfile functions | |
514 | */ | |
515 | int | |
516 | prng_check_seedfile(char *filename) { | |
517 | ||
518 | struct stat st; | |
519 | ||
520 | /* FIXME raceable: eg replace seed between this stat and subsequent open */ | |
521 | /* Not such a problem because we don't trust the seed file anyway */ | |
522 | if (lstat(filename, &st) == -1) { | |
523 | /* Fail on hard errors */ | |
524 | if (errno != ENOENT) | |
525 | fatal("Couldn't stat random seed file \"%s\": %s", filename, | |
526 | strerror(errno)); | |
527 | ||
528 | return(0); | |
529 | } | |
530 | ||
531 | /* regular file? */ | |
532 | if (!S_ISREG(st.st_mode)) | |
533 | fatal("PRNG seedfile %.100s is not a regular file", filename); | |
534 | ||
535 | /* mode 0600, owned by root or the current user? */ | |
d02a3a00 | 536 | if (((st.st_mode & 0177) != 0) || !(st.st_uid == getuid())) |
b7a87eea | 537 | fatal("PRNG seedfile %.100s must be mode 0600, owned by uid %d", |
538 | filename, getuid()); | |
539 | ||
540 | return(1); | |
541 | } | |
542 | ||
543 | void | |
544 | prng_write_seedfile(void) { | |
545 | int fd; | |
546 | char seed[1024]; | |
547 | char filename[1024]; | |
548 | struct passwd *pw; | |
549 | ||
550 | /* Don't bother if we have already saved a seed */ | |
551 | if (prng_seed_saved) | |
552 | return; | |
553 | ||
52bcc044 | 554 | prng_seed_saved = 1; |
555 | ||
b7a87eea | 556 | pw = getpwuid(getuid()); |
557 | if (pw == NULL) | |
558 | fatal("Couldn't get password entry for current user (%i): %s", | |
559 | getuid(), strerror(errno)); | |
560 | ||
561 | /* Try to ensure that the parent directory is there */ | |
562 | snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir, | |
563 | SSH_USER_DIR); | |
564 | mkdir(filename, 0700); | |
565 | ||
566 | snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir, | |
567 | SSH_PRNG_SEED_FILE); | |
568 | ||
569 | debug("writing PRNG seed to file %.100s", filename); | |
570 | ||
571 | RAND_bytes(seed, sizeof(seed)); | |
572 | ||
573 | /* Don't care if the seed doesn't exist */ | |
574 | prng_check_seedfile(filename); | |
575 | ||
576 | if ((fd = open(filename, O_WRONLY|O_TRUNC|O_CREAT, 0600)) == -1) | |
577 | fatal("couldn't access PRNG seedfile %.100s (%.100s)", filename, | |
578 | strerror(errno)); | |
579 | ||
580 | if (atomicio(write, fd, &seed, sizeof(seed)) != sizeof(seed)) | |
581 | fatal("problem writing PRNG seedfile %.100s (%.100s)", filename, | |
582 | strerror(errno)); | |
583 | ||
584 | close(fd); | |
585 | } | |
586 | ||
587 | void | |
588 | prng_read_seedfile(void) { | |
589 | int fd; | |
590 | char seed[1024]; | |
591 | char filename[1024]; | |
592 | struct passwd *pw; | |
593 | ||
594 | pw = getpwuid(getuid()); | |
595 | if (pw == NULL) | |
596 | fatal("Couldn't get password entry for current user (%i): %s", | |
597 | getuid(), strerror(errno)); | |
598 | ||
599 | snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir, | |
600 | SSH_PRNG_SEED_FILE); | |
601 | ||
602 | debug("loading PRNG seed from file %.100s", filename); | |
603 | ||
604 | if (!prng_check_seedfile(filename)) { | |
605 | verbose("Random seed file not found, creating new"); | |
606 | prng_write_seedfile(); | |
607 | ||
608 | /* Reseed immediatly */ | |
609 | (void)stir_from_system(); | |
610 | (void)stir_from_programs(); | |
611 | return; | |
612 | } | |
613 | ||
614 | /* open the file and read in the seed */ | |
615 | fd = open(filename, O_RDONLY); | |
616 | if (fd == -1) | |
617 | fatal("could not open PRNG seedfile %.100s (%.100s)", filename, | |
618 | strerror(errno)); | |
619 | ||
620 | if (atomicio(read, fd, &seed, sizeof(seed)) != sizeof(seed)) { | |
621 | verbose("invalid or short read from PRNG seedfile %.100s - ignoring", | |
622 | filename); | |
623 | memset(seed, '\0', sizeof(seed)); | |
624 | } | |
625 | close(fd); | |
626 | ||
627 | /* stir in the seed, with estimated entropy zero */ | |
628 | RAND_add(&seed, sizeof(seed), 0.0); | |
bfc9a610 | 629 | } |
b7a87eea | 630 | |
d3083fbd | 631 | |
632 | /* | |
633 | * entropy command initialisation functions | |
634 | */ | |
d3083fbd | 635 | int |
636 | prng_read_commands(char *cmdfilename) | |
637 | { | |
638 | FILE *f; | |
d3083fbd | 639 | char *cp; |
48c99b2c | 640 | char line[1024]; |
641 | char cmd[1024]; | |
642 | char path[256]; | |
d3083fbd | 643 | int linenum; |
d3083fbd | 644 | int num_cmds = 64; |
645 | int cur_cmd = 0; | |
48c99b2c | 646 | double est; |
647 | entropy_source_t *entcmd; | |
d3083fbd | 648 | |
649 | f = fopen(cmdfilename, "r"); | |
650 | if (!f) { | |
651 | fatal("couldn't read entropy commands file %.100s: %.100s", | |
652 | cmdfilename, strerror(errno)); | |
653 | } | |
654 | ||
d3083fbd | 655 | entcmd = (entropy_source_t *)xmalloc(num_cmds * sizeof(entropy_source_t)); |
656 | memset(entcmd, '\0', num_cmds * sizeof(entropy_source_t)); | |
657 | ||
48c99b2c | 658 | /* Read in file */ |
659 | linenum = 0; | |
d3083fbd | 660 | while (fgets(line, sizeof(line), f)) { |
48c99b2c | 661 | int arg; |
662 | char *argv; | |
663 | ||
d3083fbd | 664 | linenum++; |
665 | ||
666 | /* skip leading whitespace, test for blank line or comment */ | |
667 | cp = line + strspn(line, WHITESPACE); | |
668 | if ((*cp == 0) || (*cp == '#')) | |
669 | continue; /* done with this line */ | |
670 | ||
48c99b2c | 671 | /* First non-whitespace char should be double quote delimiting */ |
672 | /* commandline */ | |
673 | if (*cp != '"') { | |
674 | error("bad entropy command, %.100s line %d", cmdfilename, | |
675 | linenum); | |
676 | continue; | |
677 | } | |
d3083fbd | 678 | |
48c99b2c | 679 | /* first token, command args (incl. argv[0]) in double quotes */ |
680 | cp = strtok(cp, "\""); | |
681 | if (cp == NULL) { | |
682 | error("missing or bad command string, %.100s line %d -- ignored", | |
683 | cmdfilename, linenum); | |
684 | continue; | |
685 | } | |
686 | strlcpy(cmd, cp, sizeof(cmd)); | |
687 | ||
688 | /* second token, full command path */ | |
689 | if ((cp = strtok(NULL, WHITESPACE)) == NULL) { | |
690 | error("missing command path, %.100s line %d -- ignored", | |
691 | cmdfilename, linenum); | |
692 | continue; | |
693 | } | |
d3083fbd | 694 | |
48c99b2c | 695 | /* did configure mark this as dead? */ |
696 | if (strncmp("undef", cp, 5) == 0) | |
697 | continue; | |
d3083fbd | 698 | |
48c99b2c | 699 | strlcpy(path, cp, sizeof(path)); |
700 | ||
701 | /* third token, entropy rate estimate for this command */ | |
702 | if ((cp = strtok(NULL, WHITESPACE)) == NULL) { | |
703 | error("missing entropy estimate, %.100s line %d -- ignored", | |
704 | cmdfilename, linenum); | |
705 | continue; | |
706 | } | |
707 | est = strtod(cp, &argv); | |
708 | ||
709 | /* end of line */ | |
710 | if ((cp = strtok(NULL, WHITESPACE)) != NULL) { | |
711 | error("garbage at end of line %d in %.100s -- ignored", linenum, | |
712 | cmdfilename); | |
d3083fbd | 713 | continue; |
714 | } | |
48c99b2c | 715 | |
716 | /* save the command for debug messages */ | |
717 | entcmd[cur_cmd].cmdstring = xstrdup(cmd); | |
718 | ||
719 | /* split the command args */ | |
720 | cp = strtok(cmd, WHITESPACE); | |
721 | arg = 0; | |
722 | argv = NULL; | |
723 | do { | |
724 | char *s = (char*)xmalloc(strlen(cp) + 1); | |
725 | strncpy(s, cp, strlen(cp) + 1); | |
726 | entcmd[cur_cmd].args[arg] = s; | |
727 | arg++; | |
728 | } while ((arg < 5) && (cp = strtok(NULL, WHITESPACE))); | |
729 | ||
730 | if (strtok(NULL, WHITESPACE)) | |
731 | error("ignored extra command elements (max 5), %.100s line %d", | |
732 | cmdfilename, linenum); | |
733 | ||
734 | /* Copy the command path and rate estimate */ | |
735 | entcmd[cur_cmd].path = xstrdup(path); | |
736 | entcmd[cur_cmd].rate = est; | |
737 | ||
738 | /* Initialise other values */ | |
739 | entcmd[cur_cmd].sticky_badness = 1; | |
740 | ||
741 | cur_cmd++; | |
742 | ||
743 | /* If we've filled the array, reallocate it twice the size */ | |
744 | /* Do this now because even if this we're on the last command, | |
745 | we need another slot to mark the last entry */ | |
746 | if (cur_cmd == num_cmds) { | |
747 | num_cmds *= 2; | |
748 | entcmd = xrealloc(entcmd, num_cmds * sizeof(entropy_source_t)); | |
749 | } | |
d3083fbd | 750 | } |
751 | ||
752 | /* zero the last entry */ | |
753 | memset(&entcmd[cur_cmd], '\0', sizeof(entropy_source_t)); | |
48c99b2c | 754 | |
d3083fbd | 755 | /* trim to size */ |
756 | entropy_sources = xrealloc(entcmd, (cur_cmd+1) * sizeof(entropy_source_t)); | |
757 | ||
758 | debug("loaded %d entropy commands from %.100s", cur_cmd, cmdfilename); | |
759 | ||
760 | return (cur_cmd >= MIN_ENTROPY_SOURCES); | |
761 | } | |
762 | ||
b7a87eea | 763 | /* |
764 | * Write a keyfile at exit | |
765 | */ | |
766 | void | |
767 | prng_seed_cleanup(void *junk) | |
768 | { | |
769 | prng_write_seedfile(); | |
770 | } | |
771 | ||
bfc9a610 | 772 | /* |
b7a87eea | 773 | * Conditionally Seed OpenSSL's random number pool from |
774 | * syscalls and program output | |
bfc9a610 | 775 | */ |
776 | void | |
777 | seed_rng(void) | |
778 | { | |
a64009ad | 779 | void *old_sigchld_handler; |
780 | ||
d3083fbd | 781 | if (!prng_commands_loaded) { |
782 | if (!prng_read_commands(SSH_PRNG_COMMAND_FILE)) | |
783 | fatal("PRNG initialisation failed -- exiting."); | |
784 | prng_commands_loaded = 1; | |
785 | } | |
786 | ||
a64009ad | 787 | /* Make sure some other sigchld handler doesn't reap our entropy */ |
788 | /* commands */ | |
789 | old_sigchld_handler = signal(SIGCHLD, SIG_DFL); | |
790 | ||
6c081128 | 791 | debug("Seeding random number generator."); |
792 | debug("OpenSSL random status is now %i\n", RAND_status()); | |
793 | debug("%i bytes from system calls", (int)stir_from_system()); | |
794 | debug("%i bytes from programs", (int)stir_from_programs()); | |
795 | debug("OpenSSL random status is now %i\n", RAND_status()); | |
b7a87eea | 796 | |
a64009ad | 797 | signal(SIGCHLD, old_sigchld_handler); |
798 | ||
ad85db64 | 799 | if (!RAND_status()) |
800 | fatal("Couldn't initialise builtin random number generator -- exiting."); | |
801 | ||
b7a87eea | 802 | if (!prng_seed_loaded) |
803 | { | |
804 | prng_seed_loaded = 1; | |
805 | prng_seed_saved = 0; | |
806 | prng_read_seedfile(); | |
807 | fatal_add_cleanup(prng_seed_cleanup, NULL); | |
808 | atexit(prng_write_seedfile); | |
809 | } | |
bfc9a610 | 810 | } |
811 | #endif /* defined(EGD_SOCKET) || defined(RANDOM_POOL) */ |