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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 | ||
35484284 | 27 | #include <openssl/rand.h> |
28 | #include <openssl/sha.h> | |
bfc9a610 | 29 | |
819b676f | 30 | /* SunOS 4.4.4 needs this */ |
31 | #ifdef HAVE_FLOATINGPOINT_H | |
32 | # include <floatingpoint.h> | |
33 | #endif /* HAVE_FLOATINGPOINT_H */ | |
34 | ||
42f11eb2 | 35 | #include "ssh.h" |
36 | #include "xmalloc.h" | |
37 | #include "atomicio.h" | |
38 | #include "log.h" | |
39 | ||
bfc9a610 | 40 | RCSID("$Id$"); |
41 | ||
bfc9a610 | 42 | #ifndef offsetof |
43 | # define offsetof(type, member) ((size_t) &((type *)0)->member) | |
44 | #endif | |
48c99b2c | 45 | |
48c99b2c | 46 | /* Number of times to pass through command list gathering entropy */ |
47 | #define NUM_ENTROPY_RUNS 1 | |
48 | ||
49 | /* Scale entropy estimates back by this amount on subsequent runs */ | |
50 | #define SCALE_PER_RUN 10.0 | |
51 | ||
52 | /* Minimum number of commands to be considered valid */ | |
53 | #define MIN_ENTROPY_SOURCES 16 | |
54 | ||
55 | #define WHITESPACE " \t\n" | |
56 | ||
cbd7492e | 57 | #ifndef RUSAGE_SELF |
58 | # define RUSAGE_SELF 0 | |
59 | #endif | |
60 | #ifndef RUSAGE_CHILDREN | |
61 | # define RUSAGE_CHILDREN 0 | |
62 | #endif | |
63 | ||
48c99b2c | 64 | #if defined(EGD_SOCKET) || defined(RANDOM_POOL) |
65 | ||
66 | #ifdef EGD_SOCKET | |
bfc9a610 | 67 | /* Collect entropy from EGD */ |
be0b9bb7 | 68 | int get_random_bytes(unsigned char *buf, int len) |
bfc9a610 | 69 | { |
be0b9bb7 | 70 | int fd; |
71 | char msg[2]; | |
bfc9a610 | 72 | struct sockaddr_un addr; |
73 | int addr_len; | |
74 | ||
be0b9bb7 | 75 | /* Sanity checks */ |
bfc9a610 | 76 | if (sizeof(EGD_SOCKET) > sizeof(addr.sun_path)) |
77 | fatal("Random pool path is too long"); | |
be0b9bb7 | 78 | if (len > 255) |
79 | fatal("Too many bytes to read from EGD"); | |
80 | ||
81 | memset(&addr, '\0', sizeof(addr)); | |
82 | addr.sun_family = AF_UNIX; | |
48c99b2c | 83 | strlcpy(addr.sun_path, EGD_SOCKET, sizeof(addr.sun_path)); |
bfc9a610 | 84 | addr_len = offsetof(struct sockaddr_un, sun_path) + sizeof(EGD_SOCKET); |
85 | ||
be0b9bb7 | 86 | fd = socket(AF_UNIX, SOCK_STREAM, 0); |
87 | if (fd == -1) { | |
88 | error("Couldn't create AF_UNIX socket: %s", strerror(errno)); | |
89 | return(0); | |
90 | } | |
bfc9a610 | 91 | |
be0b9bb7 | 92 | if (connect(fd, (struct sockaddr*)&addr, addr_len) == -1) { |
93 | error("Couldn't connect to EGD socket \"%s\": %s", | |
94 | addr.sun_path, strerror(errno)); | |
95 | close(fd); | |
96 | return(0); | |
97 | } | |
bfc9a610 | 98 | |
be0b9bb7 | 99 | /* Send blocking read request to EGD */ |
100 | msg[0] = 0x02; | |
101 | msg[1] = len; | |
102 | ||
103 | if (atomicio(write, fd, msg, sizeof(msg)) != sizeof(msg)) { | |
104 | error("Couldn't write to EGD socket \"%s\": %s", | |
105 | EGD_SOCKET, strerror(errno)); | |
106 | close(fd); | |
107 | return(0); | |
108 | } | |
bfc9a610 | 109 | |
be0b9bb7 | 110 | if (atomicio(read, fd, buf, len) != len) { |
111 | error("Couldn't read from EGD socket \"%s\": %s", | |
112 | EGD_SOCKET, strerror(errno)); | |
113 | close(fd); | |
114 | return(0); | |
115 | } | |
116 | ||
117 | close(fd); | |
118 | ||
119 | return(1); | |
bfc9a610 | 120 | } |
121 | #else /* !EGD_SOCKET */ | |
122 | #ifdef RANDOM_POOL | |
123 | /* Collect entropy from /dev/urandom or pipe */ | |
be0b9bb7 | 124 | int get_random_bytes(unsigned char *buf, int len) |
bfc9a610 | 125 | { |
be0b9bb7 | 126 | int random_pool; |
bfc9a610 | 127 | |
be0b9bb7 | 128 | random_pool = open(RANDOM_POOL, O_RDONLY); |
bfc9a610 | 129 | if (random_pool == -1) { |
be0b9bb7 | 130 | error("Couldn't open random pool \"%s\": %s", |
131 | RANDOM_POOL, strerror(errno)); | |
132 | return(0); | |
bfc9a610 | 133 | } |
134 | ||
be0b9bb7 | 135 | if (atomicio(read, random_pool, buf, len) != len) { |
136 | error("Couldn't read from random pool \"%s\": %s", | |
137 | RANDOM_POOL, strerror(errno)); | |
138 | close(random_pool); | |
139 | return(0); | |
140 | } | |
141 | ||
142 | close(random_pool); | |
143 | ||
144 | return(1); | |
bfc9a610 | 145 | } |
146 | #endif /* RANDOM_POOL */ | |
147 | #endif /* EGD_SOCKET */ | |
148 | ||
48c99b2c | 149 | /* |
150 | * Seed OpenSSL's random number pool from Kernel random number generator | |
151 | * or EGD | |
152 | */ | |
153 | void | |
154 | seed_rng(void) | |
155 | { | |
156 | char buf[32]; | |
157 | ||
158 | debug("Seeding random number generator"); | |
be0b9bb7 | 159 | |
b5b3f75d | 160 | if (!get_random_bytes(buf, sizeof(buf))) { |
161 | if (!RAND_status()) | |
162 | fatal("Entropy collection failed and entropy exhausted"); | |
163 | } else { | |
164 | RAND_add(buf, sizeof(buf), sizeof(buf)); | |
165 | } | |
166 | ||
48c99b2c | 167 | memset(buf, '\0', sizeof(buf)); |
168 | } | |
169 | ||
264dce47 | 170 | /* No-op */ |
171 | void init_rng(void) {} | |
172 | ||
48c99b2c | 173 | #else /* defined(EGD_SOCKET) || defined(RANDOM_POOL) */ |
174 | ||
bfc9a610 | 175 | /* |
176 | * FIXME: proper entropy estimations. All current values are guesses | |
b7a87eea | 177 | * FIXME: (ATL) do estimates at compile time? |
bfc9a610 | 178 | * FIXME: More entropy sources |
179 | */ | |
180 | ||
b7a87eea | 181 | /* slow command timeouts (all in milliseconds) */ |
182 | /* static int entropy_timeout_default = ENTROPY_TIMEOUT_MSEC; */ | |
183 | static int entropy_timeout_current = ENTROPY_TIMEOUT_MSEC; | |
184 | ||
d3083fbd | 185 | static int prng_seed_saved = 0; |
264dce47 | 186 | static int prng_initialised = 0; |
187 | uid_t original_uid; | |
bfc9a610 | 188 | |
189 | typedef struct | |
190 | { | |
191 | /* Proportion of data that is entropy */ | |
192 | double rate; | |
b7a87eea | 193 | /* Counter goes positive if this command times out */ |
194 | unsigned int badness; | |
195 | /* Increases by factor of two each timeout */ | |
196 | unsigned int sticky_badness; | |
bfc9a610 | 197 | /* Path to executable */ |
d3083fbd | 198 | char *path; |
bfc9a610 | 199 | /* argv to pass to executable */ |
d3083fbd | 200 | char *args[5]; |
ad85db64 | 201 | /* full command string (debug) */ |
202 | char *cmdstring; | |
bfc9a610 | 203 | } entropy_source_t; |
204 | ||
b7a87eea | 205 | double stir_from_system(void); |
206 | double stir_from_programs(void); | |
207 | double stir_gettimeofday(double entropy_estimate); | |
208 | double stir_clock(double entropy_estimate); | |
209 | double stir_rusage(int who, double entropy_estimate); | |
210 | double hash_output_from_command(entropy_source_t *src, char *hash); | |
211 | ||
d3083fbd | 212 | /* this is initialised from a file, by prng_read_commands() */ |
213 | entropy_source_t *entropy_sources = NULL; | |
bfc9a610 | 214 | |
bfc9a610 | 215 | double |
216 | stir_from_system(void) | |
217 | { | |
218 | double total_entropy_estimate; | |
219 | long int i; | |
220 | ||
221 | total_entropy_estimate = 0; | |
222 | ||
223 | i = getpid(); | |
cbd7492e | 224 | RAND_add(&i, sizeof(i), 0.5); |
bfc9a610 | 225 | total_entropy_estimate += 0.1; |
226 | ||
227 | i = getppid(); | |
cbd7492e | 228 | RAND_add(&i, sizeof(i), 0.5); |
bfc9a610 | 229 | total_entropy_estimate += 0.1; |
230 | ||
231 | i = getuid(); | |
232 | RAND_add(&i, sizeof(i), 0.0); | |
233 | i = getgid(); | |
234 | RAND_add(&i, sizeof(i), 0.0); | |
235 | ||
236 | total_entropy_estimate += stir_gettimeofday(1.0); | |
cbd7492e | 237 | total_entropy_estimate += stir_clock(0.5); |
bfc9a610 | 238 | total_entropy_estimate += stir_rusage(RUSAGE_SELF, 2.0); |
239 | ||
240 | return(total_entropy_estimate); | |
241 | } | |
242 | ||
243 | double | |
244 | stir_from_programs(void) | |
245 | { | |
246 | int i; | |
247 | int c; | |
248 | double entropy_estimate; | |
249 | double total_entropy_estimate; | |
250 | char hash[SHA_DIGEST_LENGTH]; | |
251 | ||
bfc9a610 | 252 | total_entropy_estimate = 0; |
48c99b2c | 253 | for(i = 0; i < NUM_ENTROPY_RUNS; i++) { |
bfc9a610 | 254 | c = 0; |
255 | while (entropy_sources[c].path != NULL) { | |
bfc9a610 | 256 | |
b7a87eea | 257 | if (!entropy_sources[c].badness) { |
258 | /* Hash output from command */ | |
259 | entropy_estimate = hash_output_from_command(&entropy_sources[c], hash); | |
260 | ||
261 | /* Scale back entropy estimate according to command's rate */ | |
262 | entropy_estimate *= entropy_sources[c].rate; | |
bfc9a610 | 263 | |
b7a87eea | 264 | /* Upper bound of entropy estimate is SHA_DIGEST_LENGTH */ |
265 | if (entropy_estimate > SHA_DIGEST_LENGTH) | |
266 | entropy_estimate = SHA_DIGEST_LENGTH; | |
bfc9a610 | 267 | |
48c99b2c | 268 | /* Scale back estimates for subsequent passes through list */ |
269 | entropy_estimate /= SCALE_PER_RUN * (i + 1.0); | |
bfc9a610 | 270 | |
b7a87eea | 271 | /* Stir it in */ |
272 | RAND_add(hash, sizeof(hash), entropy_estimate); | |
bfc9a610 | 273 | |
22d89d24 | 274 | debug3("Got %0.2f bytes of entropy from '%s'", entropy_estimate, |
ad85db64 | 275 | entropy_sources[c].cmdstring); |
bfc9a610 | 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 { | |
22d89d24 | 285 | debug2("Command '%s' disabled (badness %d)", |
ad85db64 | 286 | entropy_sources[c].cmdstring, entropy_sources[c].badness); |
b7a87eea | 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 | ||
22d89d24 | 371 | debug3("Reading output from \'%s\'", src->cmdstring); |
372 | ||
bfc9a610 | 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 | ||
264dce47 | 398 | setuid(original_uid); |
b7a87eea | 399 | execv(src->path, (char**)(src->args)); |
ad85db64 | 400 | debug("(child) Couldn't exec '%s': %s", src->cmdstring, |
401 | strerror(errno)); | |
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 | |
264dce47 | 435 | RAND_add(&tv, sizeof(tv), 0.0); |
436 | ||
b7a87eea | 437 | switch (ret) { |
438 | case 0: | |
439 | /* timer expired */ | |
440 | error_abort = 1; | |
441 | break; | |
b7a87eea | 442 | case 1: |
443 | /* command input */ | |
444 | bytes_read = read(p[0], buf, sizeof(buf)); | |
264dce47 | 445 | RAND_add(&bytes_read, sizeof(&bytes_read), 0.0); |
b7a87eea | 446 | if (bytes_read == -1) { |
447 | error_abort = 1; | |
448 | break; | |
264dce47 | 449 | } else if (bytes_read) { |
ad85db64 | 450 | SHA1_Update(&sha, buf, bytes_read); |
451 | total_bytes_read += bytes_read; | |
264dce47 | 452 | } else { |
ad85db64 | 453 | cmd_eof = 1; |
264dce47 | 454 | } |
b7a87eea | 455 | break; |
b7a87eea | 456 | case -1: |
457 | default: | |
264dce47 | 458 | /* error */ |
ad85db64 | 459 | debug("Command '%s': select() failed: %s", src->cmdstring, |
460 | strerror(errno)); | |
b7a87eea | 461 | error_abort = 1; |
462 | break; | |
264dce47 | 463 | } |
464 | } | |
b7a87eea | 465 | |
bfc9a610 | 466 | SHA1_Final(hash, &sha); |
467 | ||
468 | close(p[0]); | |
ad85db64 | 469 | |
22d89d24 | 470 | debug3("Time elapsed: %d msec", msec_elapsed); |
bfc9a610 | 471 | |
472 | if (waitpid(pid, &status, 0) == -1) { | |
22d89d24 | 473 | error("Couldn't wait for child '%s' completion: %s", src->cmdstring, |
ad85db64 | 474 | strerror(errno)); |
b7a87eea | 475 | return(0.0); |
bfc9a610 | 476 | } |
477 | ||
478 | RAND_add(&status, sizeof(&status), 0.0); | |
479 | ||
b7a87eea | 480 | if (error_abort) { |
481 | /* closing p[0] on timeout causes the entropy command to | |
482 | * SIGPIPE. Take whatever output we got, and mark this command | |
483 | * as slow */ | |
22d89d24 | 484 | debug2("Command '%s' timed out", src->cmdstring); |
b7a87eea | 485 | src->sticky_badness *= 2; |
486 | src->badness = src->sticky_badness; | |
bfc9a610 | 487 | return(total_bytes_read); |
b7a87eea | 488 | } |
489 | ||
490 | if (WIFEXITED(status)) { | |
491 | if (WEXITSTATUS(status)==0) { | |
492 | return(total_bytes_read); | |
493 | } else { | |
22d89d24 | 494 | debug2("Command '%s' exit status was %d", src->cmdstring, |
48c99b2c | 495 | WEXITSTATUS(status)); |
b7a87eea | 496 | src->badness = src->sticky_badness = 128; |
497 | return (0.0); | |
498 | } | |
499 | } else if (WIFSIGNALED(status)) { | |
22d89d24 | 500 | debug2("Command '%s' returned on uncaught signal %d !", src->cmdstring, |
48c99b2c | 501 | status); |
b7a87eea | 502 | src->badness = src->sticky_badness = 128; |
503 | return(0.0); | |
504 | } else | |
505 | return(0.0); | |
506 | } | |
507 | ||
508 | /* | |
509 | * prng seedfile functions | |
510 | */ | |
511 | int | |
512 | prng_check_seedfile(char *filename) { | |
513 | ||
514 | struct stat st; | |
515 | ||
516 | /* FIXME raceable: eg replace seed between this stat and subsequent open */ | |
517 | /* Not such a problem because we don't trust the seed file anyway */ | |
518 | if (lstat(filename, &st) == -1) { | |
5b2d4b75 | 519 | /* Give up on hard errors */ |
b7a87eea | 520 | if (errno != ENOENT) |
5b2d4b75 | 521 | debug("WARNING: Couldn't stat random seed file \"%s\": %s", |
522 | filename, strerror(errno)); | |
b7a87eea | 523 | |
524 | return(0); | |
525 | } | |
526 | ||
527 | /* regular file? */ | |
528 | if (!S_ISREG(st.st_mode)) | |
529 | fatal("PRNG seedfile %.100s is not a regular file", filename); | |
530 | ||
531 | /* mode 0600, owned by root or the current user? */ | |
5b2d4b75 | 532 | if (((st.st_mode & 0177) != 0) || !(st.st_uid == original_uid)) { |
533 | debug("WARNING: PRNG seedfile %.100s must be mode 0600, owned by uid %d", | |
b7a87eea | 534 | filename, getuid()); |
5b2d4b75 | 535 | return(0); |
536 | } | |
537 | ||
b7a87eea | 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 | ||
264dce47 | 552 | setuid(original_uid); |
553 | ||
52bcc044 | 554 | prng_seed_saved = 1; |
555 | ||
264dce47 | 556 | pw = getpwuid(original_uid); |
b7a87eea | 557 | if (pw == NULL) |
558 | fatal("Couldn't get password entry for current user (%i): %s", | |
264dce47 | 559 | original_uid, strerror(errno)); |
b7a87eea | 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 | ||
5b2d4b75 | 576 | if ((fd = open(filename, O_WRONLY|O_TRUNC|O_CREAT, 0600)) == -1) { |
577 | debug("WARNING: couldn't access PRNG seedfile %.100s (%.100s)", | |
578 | filename, strerror(errno)); | |
579 | } else { | |
580 | if (atomicio(write, fd, &seed, sizeof(seed)) != sizeof(seed)) | |
581 | fatal("problem writing PRNG seedfile %.100s (%.100s)", filename, | |
582 | strerror(errno)); | |
b7a87eea | 583 | |
5b2d4b75 | 584 | close(fd); |
585 | } | |
b7a87eea | 586 | } |
587 | ||
588 | void | |
589 | prng_read_seedfile(void) { | |
590 | int fd; | |
591 | char seed[1024]; | |
592 | char filename[1024]; | |
593 | struct passwd *pw; | |
594 | ||
264dce47 | 595 | pw = getpwuid(original_uid); |
b7a87eea | 596 | if (pw == NULL) |
597 | fatal("Couldn't get password entry for current user (%i): %s", | |
264dce47 | 598 | original_uid, strerror(errno)); |
b7a87eea | 599 | |
600 | snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir, | |
601 | SSH_PRNG_SEED_FILE); | |
602 | ||
603 | debug("loading PRNG seed from file %.100s", filename); | |
604 | ||
605 | if (!prng_check_seedfile(filename)) { | |
52ce34a2 | 606 | verbose("Random seed file not found or not valid, ignoring."); |
b7a87eea | 607 | return; |
608 | } | |
609 | ||
610 | /* open the file and read in the seed */ | |
611 | fd = open(filename, O_RDONLY); | |
612 | if (fd == -1) | |
613 | fatal("could not open PRNG seedfile %.100s (%.100s)", filename, | |
614 | strerror(errno)); | |
615 | ||
616 | if (atomicio(read, fd, &seed, sizeof(seed)) != sizeof(seed)) { | |
617 | verbose("invalid or short read from PRNG seedfile %.100s - ignoring", | |
618 | filename); | |
619 | memset(seed, '\0', sizeof(seed)); | |
620 | } | |
621 | close(fd); | |
622 | ||
623 | /* stir in the seed, with estimated entropy zero */ | |
624 | RAND_add(&seed, sizeof(seed), 0.0); | |
bfc9a610 | 625 | } |
b7a87eea | 626 | |
d3083fbd | 627 | |
628 | /* | |
629 | * entropy command initialisation functions | |
630 | */ | |
d3083fbd | 631 | int |
632 | prng_read_commands(char *cmdfilename) | |
633 | { | |
634 | FILE *f; | |
d3083fbd | 635 | char *cp; |
48c99b2c | 636 | char line[1024]; |
637 | char cmd[1024]; | |
638 | char path[256]; | |
d3083fbd | 639 | int linenum; |
d3083fbd | 640 | int num_cmds = 64; |
641 | int cur_cmd = 0; | |
48c99b2c | 642 | double est; |
643 | entropy_source_t *entcmd; | |
d3083fbd | 644 | |
645 | f = fopen(cmdfilename, "r"); | |
646 | if (!f) { | |
647 | fatal("couldn't read entropy commands file %.100s: %.100s", | |
648 | cmdfilename, strerror(errno)); | |
649 | } | |
650 | ||
d3083fbd | 651 | entcmd = (entropy_source_t *)xmalloc(num_cmds * sizeof(entropy_source_t)); |
652 | memset(entcmd, '\0', num_cmds * sizeof(entropy_source_t)); | |
653 | ||
48c99b2c | 654 | /* Read in file */ |
655 | linenum = 0; | |
d3083fbd | 656 | while (fgets(line, sizeof(line), f)) { |
48c99b2c | 657 | int arg; |
658 | char *argv; | |
659 | ||
d3083fbd | 660 | linenum++; |
661 | ||
662 | /* skip leading whitespace, test for blank line or comment */ | |
663 | cp = line + strspn(line, WHITESPACE); | |
664 | if ((*cp == 0) || (*cp == '#')) | |
665 | continue; /* done with this line */ | |
666 | ||
48c99b2c | 667 | /* First non-whitespace char should be double quote delimiting */ |
668 | /* commandline */ | |
669 | if (*cp != '"') { | |
670 | error("bad entropy command, %.100s line %d", cmdfilename, | |
671 | linenum); | |
672 | continue; | |
673 | } | |
d3083fbd | 674 | |
48c99b2c | 675 | /* first token, command args (incl. argv[0]) in double quotes */ |
676 | cp = strtok(cp, "\""); | |
677 | if (cp == NULL) { | |
678 | error("missing or bad command string, %.100s line %d -- ignored", | |
679 | cmdfilename, linenum); | |
680 | continue; | |
681 | } | |
682 | strlcpy(cmd, cp, sizeof(cmd)); | |
683 | ||
684 | /* second token, full command path */ | |
685 | if ((cp = strtok(NULL, WHITESPACE)) == NULL) { | |
686 | error("missing command path, %.100s line %d -- ignored", | |
687 | cmdfilename, linenum); | |
688 | continue; | |
689 | } | |
d3083fbd | 690 | |
48c99b2c | 691 | /* did configure mark this as dead? */ |
692 | if (strncmp("undef", cp, 5) == 0) | |
693 | continue; | |
d3083fbd | 694 | |
48c99b2c | 695 | strlcpy(path, cp, sizeof(path)); |
696 | ||
697 | /* third token, entropy rate estimate for this command */ | |
698 | if ((cp = strtok(NULL, WHITESPACE)) == NULL) { | |
699 | error("missing entropy estimate, %.100s line %d -- ignored", | |
700 | cmdfilename, linenum); | |
701 | continue; | |
702 | } | |
703 | est = strtod(cp, &argv); | |
704 | ||
705 | /* end of line */ | |
706 | if ((cp = strtok(NULL, WHITESPACE)) != NULL) { | |
707 | error("garbage at end of line %d in %.100s -- ignored", linenum, | |
708 | cmdfilename); | |
d3083fbd | 709 | continue; |
710 | } | |
48c99b2c | 711 | |
712 | /* save the command for debug messages */ | |
713 | entcmd[cur_cmd].cmdstring = xstrdup(cmd); | |
714 | ||
715 | /* split the command args */ | |
716 | cp = strtok(cmd, WHITESPACE); | |
717 | arg = 0; | |
718 | argv = NULL; | |
719 | do { | |
720 | char *s = (char*)xmalloc(strlen(cp) + 1); | |
721 | strncpy(s, cp, strlen(cp) + 1); | |
722 | entcmd[cur_cmd].args[arg] = s; | |
723 | arg++; | |
724 | } while ((arg < 5) && (cp = strtok(NULL, WHITESPACE))); | |
725 | ||
726 | if (strtok(NULL, WHITESPACE)) | |
727 | error("ignored extra command elements (max 5), %.100s line %d", | |
728 | cmdfilename, linenum); | |
729 | ||
730 | /* Copy the command path and rate estimate */ | |
731 | entcmd[cur_cmd].path = xstrdup(path); | |
732 | entcmd[cur_cmd].rate = est; | |
733 | ||
734 | /* Initialise other values */ | |
735 | entcmd[cur_cmd].sticky_badness = 1; | |
736 | ||
737 | cur_cmd++; | |
738 | ||
739 | /* If we've filled the array, reallocate it twice the size */ | |
740 | /* Do this now because even if this we're on the last command, | |
741 | we need another slot to mark the last entry */ | |
742 | if (cur_cmd == num_cmds) { | |
743 | num_cmds *= 2; | |
744 | entcmd = xrealloc(entcmd, num_cmds * sizeof(entropy_source_t)); | |
745 | } | |
d3083fbd | 746 | } |
747 | ||
748 | /* zero the last entry */ | |
749 | memset(&entcmd[cur_cmd], '\0', sizeof(entropy_source_t)); | |
48c99b2c | 750 | |
d3083fbd | 751 | /* trim to size */ |
752 | entropy_sources = xrealloc(entcmd, (cur_cmd+1) * sizeof(entropy_source_t)); | |
753 | ||
264dce47 | 754 | debug("Loaded %d entropy commands from %.100s", cur_cmd, cmdfilename); |
d3083fbd | 755 | |
756 | return (cur_cmd >= MIN_ENTROPY_SOURCES); | |
757 | } | |
758 | ||
b7a87eea | 759 | /* |
760 | * Write a keyfile at exit | |
761 | */ | |
762 | void | |
763 | prng_seed_cleanup(void *junk) | |
764 | { | |
765 | prng_write_seedfile(); | |
766 | } | |
767 | ||
bfc9a610 | 768 | /* |
b7a87eea | 769 | * Conditionally Seed OpenSSL's random number pool from |
770 | * syscalls and program output | |
bfc9a610 | 771 | */ |
772 | void | |
773 | seed_rng(void) | |
774 | { | |
a64009ad | 775 | void *old_sigchld_handler; |
d3083fbd | 776 | |
264dce47 | 777 | if (!prng_initialised) |
778 | fatal("RNG not initialised"); | |
779 | ||
a64009ad | 780 | /* Make sure some other sigchld handler doesn't reap our entropy */ |
781 | /* commands */ | |
782 | old_sigchld_handler = signal(SIGCHLD, SIG_DFL); | |
783 | ||
264dce47 | 784 | debug("Seeded RNG with %i bytes from programs", (int)stir_from_programs()); |
785 | debug("Seeded RNG with %i bytes from system calls", (int)stir_from_system()); | |
786 | ||
787 | if (!RAND_status()) | |
788 | fatal("Not enough entropy in RNG"); | |
b7a87eea | 789 | |
a64009ad | 790 | signal(SIGCHLD, old_sigchld_handler); |
791 | ||
ad85db64 | 792 | if (!RAND_status()) |
793 | fatal("Couldn't initialise builtin random number generator -- exiting."); | |
264dce47 | 794 | } |
ad85db64 | 795 | |
264dce47 | 796 | void init_rng(void) |
797 | { | |
e879a080 | 798 | int original_euid; |
799 | ||
264dce47 | 800 | original_uid = getuid(); |
e879a080 | 801 | original_euid = geteuid(); |
264dce47 | 802 | |
803 | /* Read in collection commands */ | |
804 | if (!prng_read_commands(SSH_PRNG_COMMAND_FILE)) | |
805 | fatal("PRNG initialisation failed -- exiting."); | |
806 | ||
807 | /* Set ourselves up to save a seed upon exit */ | |
808 | prng_seed_saved = 0; | |
e879a080 | 809 | |
810 | /* Give up privs while reading seed file */ | |
811 | if ((original_uid != original_euid) && (seteuid(original_uid) == -1)) | |
812 | fatal("Couldn't give up privileges"); | |
813 | ||
264dce47 | 814 | prng_read_seedfile(); |
e879a080 | 815 | |
816 | if ((original_uid != original_euid) && (seteuid(original_euid) == -1)) | |
817 | fatal("Couldn't restore privileges"); | |
818 | ||
264dce47 | 819 | fatal_add_cleanup(prng_seed_cleanup, NULL); |
820 | atexit(prng_write_seedfile); | |
821 | ||
822 | prng_initialised = 1; | |
bfc9a610 | 823 | } |
264dce47 | 824 | |
bfc9a610 | 825 | #endif /* defined(EGD_SOCKET) || defined(RANDOM_POOL) */ |