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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. | |
bfc9a610 | 12 | * |
13 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR | |
14 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES | |
15 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. | |
16 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, | |
17 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT | |
18 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | |
19 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | |
20 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
21 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF | |
22 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
23 | */ | |
24 | ||
25 | #include "includes.h" | |
26 | ||
27 | #include "ssh.h" | |
28 | #include "xmalloc.h" | |
29 | ||
35484284 | 30 | #include <openssl/rand.h> |
31 | #include <openssl/sha.h> | |
bfc9a610 | 32 | |
819b676f | 33 | /* SunOS 4.4.4 needs this */ |
34 | #ifdef HAVE_FLOATINGPOINT_H | |
35 | # include <floatingpoint.h> | |
36 | #endif /* HAVE_FLOATINGPOINT_H */ | |
37 | ||
bfc9a610 | 38 | RCSID("$Id$"); |
39 | ||
bfc9a610 | 40 | #ifndef offsetof |
41 | # define offsetof(type, member) ((size_t) &((type *)0)->member) | |
42 | #endif | |
48c99b2c | 43 | |
48c99b2c | 44 | /* Number of times to pass through command list gathering entropy */ |
45 | #define NUM_ENTROPY_RUNS 1 | |
46 | ||
47 | /* Scale entropy estimates back by this amount on subsequent runs */ | |
48 | #define SCALE_PER_RUN 10.0 | |
49 | ||
50 | /* Minimum number of commands to be considered valid */ | |
51 | #define MIN_ENTROPY_SOURCES 16 | |
52 | ||
53 | #define WHITESPACE " \t\n" | |
54 | ||
cbd7492e | 55 | #ifndef RUSAGE_SELF |
56 | # define RUSAGE_SELF 0 | |
57 | #endif | |
58 | #ifndef RUSAGE_CHILDREN | |
59 | # define RUSAGE_CHILDREN 0 | |
60 | #endif | |
61 | ||
48c99b2c | 62 | #if defined(EGD_SOCKET) || defined(RANDOM_POOL) |
63 | ||
64 | #ifdef EGD_SOCKET | |
bfc9a610 | 65 | /* Collect entropy from EGD */ |
be0b9bb7 | 66 | int get_random_bytes(unsigned char *buf, int len) |
bfc9a610 | 67 | { |
be0b9bb7 | 68 | int fd; |
69 | char msg[2]; | |
bfc9a610 | 70 | struct sockaddr_un addr; |
71 | int addr_len; | |
72 | ||
be0b9bb7 | 73 | /* Sanity checks */ |
bfc9a610 | 74 | if (sizeof(EGD_SOCKET) > sizeof(addr.sun_path)) |
75 | fatal("Random pool path is too long"); | |
be0b9bb7 | 76 | if (len > 255) |
77 | fatal("Too many bytes to read from EGD"); | |
78 | ||
79 | memset(&addr, '\0', sizeof(addr)); | |
80 | addr.sun_family = AF_UNIX; | |
48c99b2c | 81 | strlcpy(addr.sun_path, EGD_SOCKET, sizeof(addr.sun_path)); |
bfc9a610 | 82 | addr_len = offsetof(struct sockaddr_un, sun_path) + sizeof(EGD_SOCKET); |
83 | ||
be0b9bb7 | 84 | fd = socket(AF_UNIX, SOCK_STREAM, 0); |
85 | if (fd == -1) { | |
86 | error("Couldn't create AF_UNIX socket: %s", strerror(errno)); | |
87 | return(0); | |
88 | } | |
bfc9a610 | 89 | |
be0b9bb7 | 90 | if (connect(fd, (struct sockaddr*)&addr, addr_len) == -1) { |
91 | error("Couldn't connect to EGD socket \"%s\": %s", | |
92 | addr.sun_path, strerror(errno)); | |
93 | close(fd); | |
94 | return(0); | |
95 | } | |
bfc9a610 | 96 | |
be0b9bb7 | 97 | /* Send blocking read request to EGD */ |
98 | msg[0] = 0x02; | |
99 | msg[1] = len; | |
100 | ||
101 | if (atomicio(write, fd, msg, sizeof(msg)) != sizeof(msg)) { | |
102 | error("Couldn't write to EGD socket \"%s\": %s", | |
103 | EGD_SOCKET, strerror(errno)); | |
104 | close(fd); | |
105 | return(0); | |
106 | } | |
bfc9a610 | 107 | |
be0b9bb7 | 108 | if (atomicio(read, fd, buf, len) != len) { |
109 | error("Couldn't read from EGD socket \"%s\": %s", | |
110 | EGD_SOCKET, strerror(errno)); | |
111 | close(fd); | |
112 | return(0); | |
113 | } | |
114 | ||
115 | close(fd); | |
116 | ||
117 | return(1); | |
bfc9a610 | 118 | } |
119 | #else /* !EGD_SOCKET */ | |
120 | #ifdef RANDOM_POOL | |
121 | /* Collect entropy from /dev/urandom or pipe */ | |
be0b9bb7 | 122 | int get_random_bytes(unsigned char *buf, int len) |
bfc9a610 | 123 | { |
be0b9bb7 | 124 | int random_pool; |
bfc9a610 | 125 | |
be0b9bb7 | 126 | random_pool = open(RANDOM_POOL, O_RDONLY); |
bfc9a610 | 127 | if (random_pool == -1) { |
be0b9bb7 | 128 | error("Couldn't open random pool \"%s\": %s", |
129 | RANDOM_POOL, strerror(errno)); | |
130 | return(0); | |
bfc9a610 | 131 | } |
132 | ||
be0b9bb7 | 133 | if (atomicio(read, random_pool, buf, len) != len) { |
134 | error("Couldn't read from random pool \"%s\": %s", | |
135 | RANDOM_POOL, strerror(errno)); | |
136 | close(random_pool); | |
137 | return(0); | |
138 | } | |
139 | ||
140 | close(random_pool); | |
141 | ||
142 | return(1); | |
bfc9a610 | 143 | } |
144 | #endif /* RANDOM_POOL */ | |
145 | #endif /* EGD_SOCKET */ | |
146 | ||
48c99b2c | 147 | /* |
148 | * Seed OpenSSL's random number pool from Kernel random number generator | |
149 | * or EGD | |
150 | */ | |
151 | void | |
152 | seed_rng(void) | |
153 | { | |
154 | char buf[32]; | |
155 | ||
156 | debug("Seeding random number generator"); | |
be0b9bb7 | 157 | |
b5b3f75d | 158 | if (!get_random_bytes(buf, sizeof(buf))) { |
159 | if (!RAND_status()) | |
160 | fatal("Entropy collection failed and entropy exhausted"); | |
161 | } else { | |
162 | RAND_add(buf, sizeof(buf), sizeof(buf)); | |
163 | } | |
164 | ||
48c99b2c | 165 | memset(buf, '\0', sizeof(buf)); |
166 | } | |
167 | ||
264dce47 | 168 | /* No-op */ |
169 | void init_rng(void) {} | |
170 | ||
48c99b2c | 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 | ||
d3083fbd | 183 | static int prng_seed_saved = 0; |
264dce47 | 184 | static int prng_initialised = 0; |
185 | uid_t original_uid; | |
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 | |
22d89d24 | 272 | debug3("Got %0.2f bytes of entropy from '%s'", entropy_estimate, |
ad85db64 | 273 | entropy_sources[c].cmdstring); |
bfc9a610 | 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 { | |
22d89d24 | 283 | debug2("Command '%s' disabled (badness %d)", |
ad85db64 | 284 | entropy_sources[c].cmdstring, entropy_sources[c].badness); |
b7a87eea | 285 | |
286 | if (entropy_sources[c].badness > 0) | |
287 | entropy_sources[c].badness--; | |
288 | } | |
289 | ||
bfc9a610 | 290 | c++; |
291 | } | |
292 | } | |
293 | ||
294 | return(total_entropy_estimate); | |
295 | } | |
296 | ||
297 | double | |
298 | stir_gettimeofday(double entropy_estimate) | |
299 | { | |
300 | struct timeval tv; | |
301 | ||
302 | if (gettimeofday(&tv, NULL) == -1) | |
303 | fatal("Couldn't gettimeofday: %s", strerror(errno)); | |
304 | ||
305 | RAND_add(&tv, sizeof(tv), entropy_estimate); | |
306 | ||
307 | return(entropy_estimate); | |
308 | } | |
309 | ||
310 | double | |
311 | stir_clock(double entropy_estimate) | |
312 | { | |
313 | #ifdef HAVE_CLOCK | |
314 | clock_t c; | |
315 | ||
316 | c = clock(); | |
317 | RAND_add(&c, sizeof(c), entropy_estimate); | |
318 | ||
319 | return(entropy_estimate); | |
320 | #else /* _HAVE_CLOCK */ | |
321 | return(0); | |
322 | #endif /* _HAVE_CLOCK */ | |
323 | } | |
324 | ||
325 | double | |
326 | stir_rusage(int who, double entropy_estimate) | |
327 | { | |
328 | #ifdef HAVE_GETRUSAGE | |
329 | struct rusage ru; | |
330 | ||
b7a87eea | 331 | if (getrusage(who, &ru) == -1) |
cbd7492e | 332 | return(0); |
bfc9a610 | 333 | |
cbd7492e | 334 | RAND_add(&ru, sizeof(ru), entropy_estimate); |
bfc9a610 | 335 | |
336 | return(entropy_estimate); | |
337 | #else /* _HAVE_GETRUSAGE */ | |
338 | return(0); | |
339 | #endif /* _HAVE_GETRUSAGE */ | |
340 | } | |
341 | ||
ad85db64 | 342 | |
343 | static | |
344 | int | |
345 | _get_timeval_msec_difference(struct timeval *t1, struct timeval *t2) { | |
346 | int secdiff, usecdiff; | |
347 | ||
348 | secdiff = t2->tv_sec - t1->tv_sec; | |
349 | usecdiff = (secdiff*1000000) + (t2->tv_usec - t1->tv_usec); | |
350 | return (int)(usecdiff / 1000); | |
351 | } | |
352 | ||
bfc9a610 | 353 | double |
b7a87eea | 354 | hash_output_from_command(entropy_source_t *src, char *hash) |
bfc9a610 | 355 | { |
356 | static int devnull = -1; | |
357 | int p[2]; | |
b7a87eea | 358 | fd_set rdset; |
359 | int cmd_eof = 0, error_abort = 0; | |
ad85db64 | 360 | struct timeval tv_start, tv_current; |
361 | int msec_elapsed = 0; | |
bfc9a610 | 362 | pid_t pid; |
363 | int status; | |
ad85db64 | 364 | char buf[16384]; |
bfc9a610 | 365 | int bytes_read; |
366 | int total_bytes_read; | |
367 | SHA_CTX sha; | |
368 | ||
22d89d24 | 369 | debug3("Reading output from \'%s\'", src->cmdstring); |
370 | ||
bfc9a610 | 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 | ||
264dce47 | 396 | setuid(original_uid); |
b7a87eea | 397 | execv(src->path, (char**)(src->args)); |
ad85db64 | 398 | debug("(child) Couldn't exec '%s': %s", src->cmdstring, |
399 | strerror(errno)); | |
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 | |
264dce47 | 433 | RAND_add(&tv, sizeof(tv), 0.0); |
434 | ||
b7a87eea | 435 | switch (ret) { |
436 | case 0: | |
437 | /* timer expired */ | |
438 | error_abort = 1; | |
439 | break; | |
b7a87eea | 440 | case 1: |
441 | /* command input */ | |
442 | bytes_read = read(p[0], buf, sizeof(buf)); | |
264dce47 | 443 | RAND_add(&bytes_read, sizeof(&bytes_read), 0.0); |
b7a87eea | 444 | if (bytes_read == -1) { |
445 | error_abort = 1; | |
446 | break; | |
264dce47 | 447 | } else if (bytes_read) { |
ad85db64 | 448 | SHA1_Update(&sha, buf, bytes_read); |
449 | total_bytes_read += bytes_read; | |
264dce47 | 450 | } else { |
ad85db64 | 451 | cmd_eof = 1; |
264dce47 | 452 | } |
b7a87eea | 453 | break; |
b7a87eea | 454 | case -1: |
455 | default: | |
264dce47 | 456 | /* error */ |
ad85db64 | 457 | debug("Command '%s': select() failed: %s", src->cmdstring, |
458 | strerror(errno)); | |
b7a87eea | 459 | error_abort = 1; |
460 | break; | |
264dce47 | 461 | } |
462 | } | |
b7a87eea | 463 | |
bfc9a610 | 464 | SHA1_Final(hash, &sha); |
465 | ||
466 | close(p[0]); | |
ad85db64 | 467 | |
22d89d24 | 468 | debug3("Time elapsed: %d msec", msec_elapsed); |
bfc9a610 | 469 | |
470 | if (waitpid(pid, &status, 0) == -1) { | |
22d89d24 | 471 | error("Couldn't wait for child '%s' completion: %s", src->cmdstring, |
ad85db64 | 472 | strerror(errno)); |
b7a87eea | 473 | return(0.0); |
bfc9a610 | 474 | } |
475 | ||
476 | RAND_add(&status, sizeof(&status), 0.0); | |
477 | ||
b7a87eea | 478 | if (error_abort) { |
479 | /* closing p[0] on timeout causes the entropy command to | |
480 | * SIGPIPE. Take whatever output we got, and mark this command | |
481 | * as slow */ | |
22d89d24 | 482 | debug2("Command '%s' timed out", src->cmdstring); |
b7a87eea | 483 | src->sticky_badness *= 2; |
484 | src->badness = src->sticky_badness; | |
bfc9a610 | 485 | return(total_bytes_read); |
b7a87eea | 486 | } |
487 | ||
488 | if (WIFEXITED(status)) { | |
489 | if (WEXITSTATUS(status)==0) { | |
490 | return(total_bytes_read); | |
491 | } else { | |
22d89d24 | 492 | debug2("Command '%s' exit status was %d", src->cmdstring, |
48c99b2c | 493 | WEXITSTATUS(status)); |
b7a87eea | 494 | src->badness = src->sticky_badness = 128; |
495 | return (0.0); | |
496 | } | |
497 | } else if (WIFSIGNALED(status)) { | |
22d89d24 | 498 | debug2("Command '%s' returned on uncaught signal %d !", src->cmdstring, |
48c99b2c | 499 | status); |
b7a87eea | 500 | src->badness = src->sticky_badness = 128; |
501 | return(0.0); | |
502 | } else | |
503 | return(0.0); | |
504 | } | |
505 | ||
506 | /* | |
507 | * prng seedfile functions | |
508 | */ | |
509 | int | |
510 | prng_check_seedfile(char *filename) { | |
511 | ||
512 | struct stat st; | |
513 | ||
514 | /* FIXME raceable: eg replace seed between this stat and subsequent open */ | |
515 | /* Not such a problem because we don't trust the seed file anyway */ | |
516 | if (lstat(filename, &st) == -1) { | |
5b2d4b75 | 517 | /* Give up on hard errors */ |
b7a87eea | 518 | if (errno != ENOENT) |
5b2d4b75 | 519 | debug("WARNING: Couldn't stat random seed file \"%s\": %s", |
520 | filename, strerror(errno)); | |
b7a87eea | 521 | |
522 | return(0); | |
523 | } | |
524 | ||
525 | /* regular file? */ | |
526 | if (!S_ISREG(st.st_mode)) | |
527 | fatal("PRNG seedfile %.100s is not a regular file", filename); | |
528 | ||
529 | /* mode 0600, owned by root or the current user? */ | |
5b2d4b75 | 530 | if (((st.st_mode & 0177) != 0) || !(st.st_uid == original_uid)) { |
531 | debug("WARNING: PRNG seedfile %.100s must be mode 0600, owned by uid %d", | |
b7a87eea | 532 | filename, getuid()); |
5b2d4b75 | 533 | return(0); |
534 | } | |
535 | ||
b7a87eea | 536 | return(1); |
537 | } | |
538 | ||
539 | void | |
540 | prng_write_seedfile(void) { | |
541 | int fd; | |
542 | char seed[1024]; | |
543 | char filename[1024]; | |
544 | struct passwd *pw; | |
545 | ||
546 | /* Don't bother if we have already saved a seed */ | |
547 | if (prng_seed_saved) | |
548 | return; | |
549 | ||
264dce47 | 550 | setuid(original_uid); |
551 | ||
52bcc044 | 552 | prng_seed_saved = 1; |
553 | ||
264dce47 | 554 | pw = getpwuid(original_uid); |
b7a87eea | 555 | if (pw == NULL) |
556 | fatal("Couldn't get password entry for current user (%i): %s", | |
264dce47 | 557 | original_uid, strerror(errno)); |
b7a87eea | 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 | ||
5b2d4b75 | 574 | if ((fd = open(filename, O_WRONLY|O_TRUNC|O_CREAT, 0600)) == -1) { |
575 | debug("WARNING: couldn't access PRNG seedfile %.100s (%.100s)", | |
576 | filename, strerror(errno)); | |
577 | } else { | |
578 | if (atomicio(write, fd, &seed, sizeof(seed)) != sizeof(seed)) | |
579 | fatal("problem writing PRNG seedfile %.100s (%.100s)", filename, | |
580 | strerror(errno)); | |
b7a87eea | 581 | |
5b2d4b75 | 582 | close(fd); |
583 | } | |
b7a87eea | 584 | } |
585 | ||
586 | void | |
587 | prng_read_seedfile(void) { | |
588 | int fd; | |
589 | char seed[1024]; | |
590 | char filename[1024]; | |
591 | struct passwd *pw; | |
592 | ||
264dce47 | 593 | pw = getpwuid(original_uid); |
b7a87eea | 594 | if (pw == NULL) |
595 | fatal("Couldn't get password entry for current user (%i): %s", | |
264dce47 | 596 | original_uid, strerror(errno)); |
b7a87eea | 597 | |
598 | snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir, | |
599 | SSH_PRNG_SEED_FILE); | |
600 | ||
601 | debug("loading PRNG seed from file %.100s", filename); | |
602 | ||
603 | if (!prng_check_seedfile(filename)) { | |
52ce34a2 | 604 | verbose("Random seed file not found or not valid, ignoring."); |
b7a87eea | 605 | return; |
606 | } | |
607 | ||
608 | /* open the file and read in the seed */ | |
609 | fd = open(filename, O_RDONLY); | |
610 | if (fd == -1) | |
611 | fatal("could not open PRNG seedfile %.100s (%.100s)", filename, | |
612 | strerror(errno)); | |
613 | ||
614 | if (atomicio(read, fd, &seed, sizeof(seed)) != sizeof(seed)) { | |
615 | verbose("invalid or short read from PRNG seedfile %.100s - ignoring", | |
616 | filename); | |
617 | memset(seed, '\0', sizeof(seed)); | |
618 | } | |
619 | close(fd); | |
620 | ||
621 | /* stir in the seed, with estimated entropy zero */ | |
622 | RAND_add(&seed, sizeof(seed), 0.0); | |
bfc9a610 | 623 | } |
b7a87eea | 624 | |
d3083fbd | 625 | |
626 | /* | |
627 | * entropy command initialisation functions | |
628 | */ | |
d3083fbd | 629 | int |
630 | prng_read_commands(char *cmdfilename) | |
631 | { | |
632 | FILE *f; | |
d3083fbd | 633 | char *cp; |
48c99b2c | 634 | char line[1024]; |
635 | char cmd[1024]; | |
636 | char path[256]; | |
d3083fbd | 637 | int linenum; |
d3083fbd | 638 | int num_cmds = 64; |
639 | int cur_cmd = 0; | |
48c99b2c | 640 | double est; |
641 | entropy_source_t *entcmd; | |
d3083fbd | 642 | |
643 | f = fopen(cmdfilename, "r"); | |
644 | if (!f) { | |
645 | fatal("couldn't read entropy commands file %.100s: %.100s", | |
646 | cmdfilename, strerror(errno)); | |
647 | } | |
648 | ||
d3083fbd | 649 | entcmd = (entropy_source_t *)xmalloc(num_cmds * sizeof(entropy_source_t)); |
650 | memset(entcmd, '\0', num_cmds * sizeof(entropy_source_t)); | |
651 | ||
48c99b2c | 652 | /* Read in file */ |
653 | linenum = 0; | |
d3083fbd | 654 | while (fgets(line, sizeof(line), f)) { |
48c99b2c | 655 | int arg; |
656 | char *argv; | |
657 | ||
d3083fbd | 658 | linenum++; |
659 | ||
660 | /* skip leading whitespace, test for blank line or comment */ | |
661 | cp = line + strspn(line, WHITESPACE); | |
662 | if ((*cp == 0) || (*cp == '#')) | |
663 | continue; /* done with this line */ | |
664 | ||
48c99b2c | 665 | /* First non-whitespace char should be double quote delimiting */ |
666 | /* commandline */ | |
667 | if (*cp != '"') { | |
668 | error("bad entropy command, %.100s line %d", cmdfilename, | |
669 | linenum); | |
670 | continue; | |
671 | } | |
d3083fbd | 672 | |
48c99b2c | 673 | /* first token, command args (incl. argv[0]) in double quotes */ |
674 | cp = strtok(cp, "\""); | |
675 | if (cp == NULL) { | |
676 | error("missing or bad command string, %.100s line %d -- ignored", | |
677 | cmdfilename, linenum); | |
678 | continue; | |
679 | } | |
680 | strlcpy(cmd, cp, sizeof(cmd)); | |
681 | ||
682 | /* second token, full command path */ | |
683 | if ((cp = strtok(NULL, WHITESPACE)) == NULL) { | |
684 | error("missing command path, %.100s line %d -- ignored", | |
685 | cmdfilename, linenum); | |
686 | continue; | |
687 | } | |
d3083fbd | 688 | |
48c99b2c | 689 | /* did configure mark this as dead? */ |
690 | if (strncmp("undef", cp, 5) == 0) | |
691 | continue; | |
d3083fbd | 692 | |
48c99b2c | 693 | strlcpy(path, cp, sizeof(path)); |
694 | ||
695 | /* third token, entropy rate estimate for this command */ | |
696 | if ((cp = strtok(NULL, WHITESPACE)) == NULL) { | |
697 | error("missing entropy estimate, %.100s line %d -- ignored", | |
698 | cmdfilename, linenum); | |
699 | continue; | |
700 | } | |
701 | est = strtod(cp, &argv); | |
702 | ||
703 | /* end of line */ | |
704 | if ((cp = strtok(NULL, WHITESPACE)) != NULL) { | |
705 | error("garbage at end of line %d in %.100s -- ignored", linenum, | |
706 | cmdfilename); | |
d3083fbd | 707 | continue; |
708 | } | |
48c99b2c | 709 | |
710 | /* save the command for debug messages */ | |
711 | entcmd[cur_cmd].cmdstring = xstrdup(cmd); | |
712 | ||
713 | /* split the command args */ | |
714 | cp = strtok(cmd, WHITESPACE); | |
715 | arg = 0; | |
716 | argv = NULL; | |
717 | do { | |
718 | char *s = (char*)xmalloc(strlen(cp) + 1); | |
719 | strncpy(s, cp, strlen(cp) + 1); | |
720 | entcmd[cur_cmd].args[arg] = s; | |
721 | arg++; | |
722 | } while ((arg < 5) && (cp = strtok(NULL, WHITESPACE))); | |
723 | ||
724 | if (strtok(NULL, WHITESPACE)) | |
725 | error("ignored extra command elements (max 5), %.100s line %d", | |
726 | cmdfilename, linenum); | |
727 | ||
728 | /* Copy the command path and rate estimate */ | |
729 | entcmd[cur_cmd].path = xstrdup(path); | |
730 | entcmd[cur_cmd].rate = est; | |
731 | ||
732 | /* Initialise other values */ | |
733 | entcmd[cur_cmd].sticky_badness = 1; | |
734 | ||
735 | cur_cmd++; | |
736 | ||
737 | /* If we've filled the array, reallocate it twice the size */ | |
738 | /* Do this now because even if this we're on the last command, | |
739 | we need another slot to mark the last entry */ | |
740 | if (cur_cmd == num_cmds) { | |
741 | num_cmds *= 2; | |
742 | entcmd = xrealloc(entcmd, num_cmds * sizeof(entropy_source_t)); | |
743 | } | |
d3083fbd | 744 | } |
745 | ||
746 | /* zero the last entry */ | |
747 | memset(&entcmd[cur_cmd], '\0', sizeof(entropy_source_t)); | |
48c99b2c | 748 | |
d3083fbd | 749 | /* trim to size */ |
750 | entropy_sources = xrealloc(entcmd, (cur_cmd+1) * sizeof(entropy_source_t)); | |
751 | ||
264dce47 | 752 | debug("Loaded %d entropy commands from %.100s", cur_cmd, cmdfilename); |
d3083fbd | 753 | |
754 | return (cur_cmd >= MIN_ENTROPY_SOURCES); | |
755 | } | |
756 | ||
b7a87eea | 757 | /* |
758 | * Write a keyfile at exit | |
759 | */ | |
760 | void | |
761 | prng_seed_cleanup(void *junk) | |
762 | { | |
763 | prng_write_seedfile(); | |
764 | } | |
765 | ||
bfc9a610 | 766 | /* |
b7a87eea | 767 | * Conditionally Seed OpenSSL's random number pool from |
768 | * syscalls and program output | |
bfc9a610 | 769 | */ |
770 | void | |
771 | seed_rng(void) | |
772 | { | |
a64009ad | 773 | void *old_sigchld_handler; |
d3083fbd | 774 | |
264dce47 | 775 | if (!prng_initialised) |
776 | fatal("RNG not initialised"); | |
777 | ||
a64009ad | 778 | /* Make sure some other sigchld handler doesn't reap our entropy */ |
779 | /* commands */ | |
780 | old_sigchld_handler = signal(SIGCHLD, SIG_DFL); | |
781 | ||
264dce47 | 782 | debug("Seeded RNG with %i bytes from programs", (int)stir_from_programs()); |
783 | debug("Seeded RNG with %i bytes from system calls", (int)stir_from_system()); | |
784 | ||
785 | if (!RAND_status()) | |
786 | fatal("Not enough entropy in RNG"); | |
b7a87eea | 787 | |
a64009ad | 788 | signal(SIGCHLD, old_sigchld_handler); |
789 | ||
ad85db64 | 790 | if (!RAND_status()) |
791 | fatal("Couldn't initialise builtin random number generator -- exiting."); | |
264dce47 | 792 | } |
ad85db64 | 793 | |
264dce47 | 794 | void init_rng(void) |
795 | { | |
e879a080 | 796 | int original_euid; |
797 | ||
264dce47 | 798 | original_uid = getuid(); |
e879a080 | 799 | original_euid = geteuid(); |
264dce47 | 800 | |
801 | /* Read in collection commands */ | |
802 | if (!prng_read_commands(SSH_PRNG_COMMAND_FILE)) | |
803 | fatal("PRNG initialisation failed -- exiting."); | |
804 | ||
805 | /* Set ourselves up to save a seed upon exit */ | |
806 | prng_seed_saved = 0; | |
e879a080 | 807 | |
808 | /* Give up privs while reading seed file */ | |
809 | if ((original_uid != original_euid) && (seteuid(original_uid) == -1)) | |
810 | fatal("Couldn't give up privileges"); | |
811 | ||
264dce47 | 812 | prng_read_seedfile(); |
e879a080 | 813 | |
814 | if ((original_uid != original_euid) && (seteuid(original_euid) == -1)) | |
815 | fatal("Couldn't restore privileges"); | |
816 | ||
264dce47 | 817 | fatal_add_cleanup(prng_seed_cleanup, NULL); |
818 | atexit(prng_write_seedfile); | |
819 | ||
820 | prng_initialised = 1; | |
bfc9a610 | 821 | } |
264dce47 | 822 | |
bfc9a610 | 823 | #endif /* defined(EGD_SOCKET) || defined(RANDOM_POOL) */ |