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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" | |
effa6591 | 38 | #include "pathnames.h" |
42f11eb2 | 39 | #include "log.h" |
40 | ||
bfc9a610 | 41 | RCSID("$Id$"); |
42 | ||
bfc9a610 | 43 | #ifndef offsetof |
44 | # define offsetof(type, member) ((size_t) &((type *)0)->member) | |
45 | #endif | |
48c99b2c | 46 | |
48c99b2c | 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 | ||
264dce47 | 171 | /* No-op */ |
172 | void init_rng(void) {} | |
173 | ||
48c99b2c | 174 | #else /* defined(EGD_SOCKET) || defined(RANDOM_POOL) */ |
175 | ||
bfc9a610 | 176 | /* |
177 | * FIXME: proper entropy estimations. All current values are guesses | |
b7a87eea | 178 | * FIXME: (ATL) do estimates at compile time? |
bfc9a610 | 179 | * FIXME: More entropy sources |
180 | */ | |
181 | ||
b7a87eea | 182 | /* slow command timeouts (all in milliseconds) */ |
183 | /* static int entropy_timeout_default = ENTROPY_TIMEOUT_MSEC; */ | |
184 | static int entropy_timeout_current = ENTROPY_TIMEOUT_MSEC; | |
185 | ||
d3083fbd | 186 | static int prng_seed_saved = 0; |
264dce47 | 187 | static int prng_initialised = 0; |
188 | uid_t original_uid; | |
bfc9a610 | 189 | |
190 | typedef struct | |
191 | { | |
192 | /* Proportion of data that is entropy */ | |
193 | double rate; | |
b7a87eea | 194 | /* Counter goes positive if this command times out */ |
195 | unsigned int badness; | |
196 | /* Increases by factor of two each timeout */ | |
197 | unsigned int sticky_badness; | |
bfc9a610 | 198 | /* Path to executable */ |
d3083fbd | 199 | char *path; |
bfc9a610 | 200 | /* argv to pass to executable */ |
d3083fbd | 201 | char *args[5]; |
ad85db64 | 202 | /* full command string (debug) */ |
203 | char *cmdstring; | |
bfc9a610 | 204 | } entropy_source_t; |
205 | ||
b7a87eea | 206 | double stir_from_system(void); |
207 | double stir_from_programs(void); | |
208 | double stir_gettimeofday(double entropy_estimate); | |
209 | double stir_clock(double entropy_estimate); | |
210 | double stir_rusage(int who, double entropy_estimate); | |
211 | double hash_output_from_command(entropy_source_t *src, char *hash); | |
212 | ||
d3083fbd | 213 | /* this is initialised from a file, by prng_read_commands() */ |
214 | entropy_source_t *entropy_sources = NULL; | |
bfc9a610 | 215 | |
bfc9a610 | 216 | double |
217 | stir_from_system(void) | |
218 | { | |
219 | double total_entropy_estimate; | |
220 | long int i; | |
221 | ||
222 | total_entropy_estimate = 0; | |
223 | ||
224 | i = getpid(); | |
cbd7492e | 225 | RAND_add(&i, sizeof(i), 0.5); |
bfc9a610 | 226 | total_entropy_estimate += 0.1; |
227 | ||
228 | i = getppid(); | |
cbd7492e | 229 | RAND_add(&i, sizeof(i), 0.5); |
bfc9a610 | 230 | total_entropy_estimate += 0.1; |
231 | ||
232 | i = getuid(); | |
233 | RAND_add(&i, sizeof(i), 0.0); | |
234 | i = getgid(); | |
235 | RAND_add(&i, sizeof(i), 0.0); | |
236 | ||
237 | total_entropy_estimate += stir_gettimeofday(1.0); | |
cbd7492e | 238 | total_entropy_estimate += stir_clock(0.5); |
bfc9a610 | 239 | total_entropy_estimate += stir_rusage(RUSAGE_SELF, 2.0); |
240 | ||
241 | return(total_entropy_estimate); | |
242 | } | |
243 | ||
244 | double | |
245 | stir_from_programs(void) | |
246 | { | |
247 | int i; | |
248 | int c; | |
249 | double entropy_estimate; | |
250 | double total_entropy_estimate; | |
251 | char hash[SHA_DIGEST_LENGTH]; | |
252 | ||
bfc9a610 | 253 | total_entropy_estimate = 0; |
48c99b2c | 254 | for(i = 0; i < NUM_ENTROPY_RUNS; i++) { |
bfc9a610 | 255 | c = 0; |
256 | while (entropy_sources[c].path != NULL) { | |
bfc9a610 | 257 | |
b7a87eea | 258 | if (!entropy_sources[c].badness) { |
259 | /* Hash output from command */ | |
260 | entropy_estimate = hash_output_from_command(&entropy_sources[c], hash); | |
261 | ||
262 | /* Scale back entropy estimate according to command's rate */ | |
263 | entropy_estimate *= entropy_sources[c].rate; | |
bfc9a610 | 264 | |
b7a87eea | 265 | /* Upper bound of entropy estimate is SHA_DIGEST_LENGTH */ |
266 | if (entropy_estimate > SHA_DIGEST_LENGTH) | |
267 | entropy_estimate = SHA_DIGEST_LENGTH; | |
bfc9a610 | 268 | |
48c99b2c | 269 | /* Scale back estimates for subsequent passes through list */ |
270 | entropy_estimate /= SCALE_PER_RUN * (i + 1.0); | |
bfc9a610 | 271 | |
b7a87eea | 272 | /* Stir it in */ |
273 | RAND_add(hash, sizeof(hash), entropy_estimate); | |
bfc9a610 | 274 | |
22d89d24 | 275 | debug3("Got %0.2f bytes of entropy from '%s'", entropy_estimate, |
ad85db64 | 276 | entropy_sources[c].cmdstring); |
bfc9a610 | 277 | |
b7a87eea | 278 | total_entropy_estimate += entropy_estimate; |
bfc9a610 | 279 | |
280 | /* Execution times should be a little unpredictable */ | |
b7a87eea | 281 | total_entropy_estimate += stir_gettimeofday(0.05); |
282 | total_entropy_estimate += stir_clock(0.05); | |
283 | total_entropy_estimate += stir_rusage(RUSAGE_SELF, 0.1); | |
284 | total_entropy_estimate += stir_rusage(RUSAGE_CHILDREN, 0.1); | |
285 | } else { | |
22d89d24 | 286 | debug2("Command '%s' disabled (badness %d)", |
ad85db64 | 287 | entropy_sources[c].cmdstring, entropy_sources[c].badness); |
b7a87eea | 288 | |
289 | if (entropy_sources[c].badness > 0) | |
290 | entropy_sources[c].badness--; | |
291 | } | |
292 | ||
bfc9a610 | 293 | c++; |
294 | } | |
295 | } | |
296 | ||
297 | return(total_entropy_estimate); | |
298 | } | |
299 | ||
300 | double | |
301 | stir_gettimeofday(double entropy_estimate) | |
302 | { | |
303 | struct timeval tv; | |
304 | ||
305 | if (gettimeofday(&tv, NULL) == -1) | |
306 | fatal("Couldn't gettimeofday: %s", strerror(errno)); | |
307 | ||
308 | RAND_add(&tv, sizeof(tv), entropy_estimate); | |
309 | ||
310 | return(entropy_estimate); | |
311 | } | |
312 | ||
313 | double | |
314 | stir_clock(double entropy_estimate) | |
315 | { | |
316 | #ifdef HAVE_CLOCK | |
317 | clock_t c; | |
318 | ||
319 | c = clock(); | |
320 | RAND_add(&c, sizeof(c), entropy_estimate); | |
321 | ||
322 | return(entropy_estimate); | |
323 | #else /* _HAVE_CLOCK */ | |
324 | return(0); | |
325 | #endif /* _HAVE_CLOCK */ | |
326 | } | |
327 | ||
328 | double | |
329 | stir_rusage(int who, double entropy_estimate) | |
330 | { | |
331 | #ifdef HAVE_GETRUSAGE | |
332 | struct rusage ru; | |
333 | ||
b7a87eea | 334 | if (getrusage(who, &ru) == -1) |
cbd7492e | 335 | return(0); |
bfc9a610 | 336 | |
cbd7492e | 337 | RAND_add(&ru, sizeof(ru), entropy_estimate); |
bfc9a610 | 338 | |
339 | return(entropy_estimate); | |
340 | #else /* _HAVE_GETRUSAGE */ | |
341 | return(0); | |
342 | #endif /* _HAVE_GETRUSAGE */ | |
343 | } | |
344 | ||
ad85db64 | 345 | |
346 | static | |
347 | int | |
348 | _get_timeval_msec_difference(struct timeval *t1, struct timeval *t2) { | |
349 | int secdiff, usecdiff; | |
350 | ||
351 | secdiff = t2->tv_sec - t1->tv_sec; | |
352 | usecdiff = (secdiff*1000000) + (t2->tv_usec - t1->tv_usec); | |
353 | return (int)(usecdiff / 1000); | |
354 | } | |
355 | ||
bfc9a610 | 356 | double |
b7a87eea | 357 | hash_output_from_command(entropy_source_t *src, char *hash) |
bfc9a610 | 358 | { |
359 | static int devnull = -1; | |
360 | int p[2]; | |
b7a87eea | 361 | fd_set rdset; |
362 | int cmd_eof = 0, error_abort = 0; | |
ad85db64 | 363 | struct timeval tv_start, tv_current; |
364 | int msec_elapsed = 0; | |
bfc9a610 | 365 | pid_t pid; |
366 | int status; | |
ad85db64 | 367 | char buf[16384]; |
bfc9a610 | 368 | int bytes_read; |
369 | int total_bytes_read; | |
370 | SHA_CTX sha; | |
371 | ||
22d89d24 | 372 | debug3("Reading output from \'%s\'", src->cmdstring); |
373 | ||
bfc9a610 | 374 | if (devnull == -1) { |
375 | devnull = open("/dev/null", O_RDWR); | |
376 | if (devnull == -1) | |
377 | fatal("Couldn't open /dev/null: %s", strerror(errno)); | |
378 | } | |
379 | ||
380 | if (pipe(p) == -1) | |
381 | fatal("Couldn't open pipe: %s", strerror(errno)); | |
382 | ||
ad85db64 | 383 | (void)gettimeofday(&tv_start, NULL); /* record start time */ |
384 | ||
bfc9a610 | 385 | switch (pid = fork()) { |
386 | case -1: /* Error */ | |
387 | close(p[0]); | |
388 | close(p[1]); | |
389 | fatal("Couldn't fork: %s", strerror(errno)); | |
390 | /* NOTREACHED */ | |
391 | case 0: /* Child */ | |
b7a87eea | 392 | dup2(devnull, STDIN_FILENO); |
393 | dup2(p[1], STDOUT_FILENO); | |
394 | dup2(p[1], STDERR_FILENO); | |
bfc9a610 | 395 | close(p[0]); |
396 | close(p[1]); | |
397 | close(devnull); | |
398 | ||
264dce47 | 399 | setuid(original_uid); |
b7a87eea | 400 | execv(src->path, (char**)(src->args)); |
ad85db64 | 401 | debug("(child) Couldn't exec '%s': %s", src->cmdstring, |
402 | strerror(errno)); | |
bfc9a610 | 403 | _exit(-1); |
404 | default: /* Parent */ | |
405 | break; | |
406 | } | |
407 | ||
408 | RAND_add(&pid, sizeof(&pid), 0.0); | |
409 | ||
410 | close(p[1]); | |
411 | ||
412 | /* Hash output from child */ | |
413 | SHA1_Init(&sha); | |
414 | total_bytes_read = 0; | |
b7a87eea | 415 | |
416 | while (!error_abort && !cmd_eof) { | |
417 | int ret; | |
418 | struct timeval tv; | |
ad85db64 | 419 | int msec_remaining; |
420 | ||
421 | (void) gettimeofday(&tv_current, 0); | |
48c99b2c | 422 | msec_elapsed = _get_timeval_msec_difference(&tv_start, &tv_current); |
ad85db64 | 423 | if (msec_elapsed >= entropy_timeout_current) { |
424 | error_abort=1; | |
425 | continue; | |
426 | } | |
427 | msec_remaining = entropy_timeout_current - msec_elapsed; | |
b7a87eea | 428 | |
429 | FD_ZERO(&rdset); | |
430 | FD_SET(p[0], &rdset); | |
ad85db64 | 431 | tv.tv_sec = msec_remaining / 1000; |
432 | tv.tv_usec = (msec_remaining % 1000) * 1000; | |
b7a87eea | 433 | |
434 | ret = select(p[0]+1, &rdset, NULL, NULL, &tv); | |
ad85db64 | 435 | |
264dce47 | 436 | RAND_add(&tv, sizeof(tv), 0.0); |
437 | ||
b7a87eea | 438 | switch (ret) { |
439 | case 0: | |
440 | /* timer expired */ | |
441 | error_abort = 1; | |
442 | break; | |
b7a87eea | 443 | case 1: |
444 | /* command input */ | |
445 | bytes_read = read(p[0], buf, sizeof(buf)); | |
264dce47 | 446 | RAND_add(&bytes_read, sizeof(&bytes_read), 0.0); |
b7a87eea | 447 | if (bytes_read == -1) { |
448 | error_abort = 1; | |
449 | break; | |
264dce47 | 450 | } else if (bytes_read) { |
ad85db64 | 451 | SHA1_Update(&sha, buf, bytes_read); |
452 | total_bytes_read += bytes_read; | |
264dce47 | 453 | } else { |
ad85db64 | 454 | cmd_eof = 1; |
264dce47 | 455 | } |
b7a87eea | 456 | break; |
b7a87eea | 457 | case -1: |
458 | default: | |
264dce47 | 459 | /* error */ |
ad85db64 | 460 | debug("Command '%s': select() failed: %s", src->cmdstring, |
461 | strerror(errno)); | |
b7a87eea | 462 | error_abort = 1; |
463 | break; | |
264dce47 | 464 | } |
465 | } | |
b7a87eea | 466 | |
bfc9a610 | 467 | SHA1_Final(hash, &sha); |
468 | ||
469 | close(p[0]); | |
ad85db64 | 470 | |
22d89d24 | 471 | debug3("Time elapsed: %d msec", msec_elapsed); |
bfc9a610 | 472 | |
473 | if (waitpid(pid, &status, 0) == -1) { | |
22d89d24 | 474 | error("Couldn't wait for child '%s' completion: %s", src->cmdstring, |
ad85db64 | 475 | strerror(errno)); |
b7a87eea | 476 | return(0.0); |
bfc9a610 | 477 | } |
478 | ||
479 | RAND_add(&status, sizeof(&status), 0.0); | |
480 | ||
b7a87eea | 481 | if (error_abort) { |
482 | /* closing p[0] on timeout causes the entropy command to | |
483 | * SIGPIPE. Take whatever output we got, and mark this command | |
484 | * as slow */ | |
22d89d24 | 485 | debug2("Command '%s' timed out", src->cmdstring); |
b7a87eea | 486 | src->sticky_badness *= 2; |
487 | src->badness = src->sticky_badness; | |
bfc9a610 | 488 | return(total_bytes_read); |
b7a87eea | 489 | } |
490 | ||
491 | if (WIFEXITED(status)) { | |
492 | if (WEXITSTATUS(status)==0) { | |
493 | return(total_bytes_read); | |
494 | } else { | |
22d89d24 | 495 | debug2("Command '%s' exit status was %d", src->cmdstring, |
48c99b2c | 496 | WEXITSTATUS(status)); |
b7a87eea | 497 | src->badness = src->sticky_badness = 128; |
498 | return (0.0); | |
499 | } | |
500 | } else if (WIFSIGNALED(status)) { | |
22d89d24 | 501 | debug2("Command '%s' returned on uncaught signal %d !", src->cmdstring, |
48c99b2c | 502 | status); |
b7a87eea | 503 | src->badness = src->sticky_badness = 128; |
504 | return(0.0); | |
505 | } else | |
506 | return(0.0); | |
507 | } | |
508 | ||
509 | /* | |
510 | * prng seedfile functions | |
511 | */ | |
512 | int | |
513 | prng_check_seedfile(char *filename) { | |
514 | ||
515 | struct stat st; | |
516 | ||
517 | /* FIXME raceable: eg replace seed between this stat and subsequent open */ | |
518 | /* Not such a problem because we don't trust the seed file anyway */ | |
519 | if (lstat(filename, &st) == -1) { | |
5b2d4b75 | 520 | /* Give up on hard errors */ |
b7a87eea | 521 | if (errno != ENOENT) |
5b2d4b75 | 522 | debug("WARNING: Couldn't stat random seed file \"%s\": %s", |
523 | filename, strerror(errno)); | |
b7a87eea | 524 | |
525 | return(0); | |
526 | } | |
527 | ||
528 | /* regular file? */ | |
529 | if (!S_ISREG(st.st_mode)) | |
530 | fatal("PRNG seedfile %.100s is not a regular file", filename); | |
531 | ||
532 | /* mode 0600, owned by root or the current user? */ | |
5b2d4b75 | 533 | if (((st.st_mode & 0177) != 0) || !(st.st_uid == original_uid)) { |
534 | debug("WARNING: PRNG seedfile %.100s must be mode 0600, owned by uid %d", | |
b7a87eea | 535 | filename, getuid()); |
5b2d4b75 | 536 | return(0); |
537 | } | |
538 | ||
b7a87eea | 539 | return(1); |
540 | } | |
541 | ||
542 | void | |
543 | prng_write_seedfile(void) { | |
544 | int fd; | |
545 | char seed[1024]; | |
546 | char filename[1024]; | |
547 | struct passwd *pw; | |
548 | ||
549 | /* Don't bother if we have already saved a seed */ | |
550 | if (prng_seed_saved) | |
551 | return; | |
552 | ||
264dce47 | 553 | setuid(original_uid); |
554 | ||
52bcc044 | 555 | prng_seed_saved = 1; |
556 | ||
264dce47 | 557 | pw = getpwuid(original_uid); |
b7a87eea | 558 | if (pw == NULL) |
559 | fatal("Couldn't get password entry for current user (%i): %s", | |
264dce47 | 560 | original_uid, strerror(errno)); |
b7a87eea | 561 | |
562 | /* Try to ensure that the parent directory is there */ | |
563 | snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir, | |
effa6591 | 564 | _PATH_SSH_USER_DIR); |
b7a87eea | 565 | mkdir(filename, 0700); |
566 | ||
567 | snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir, | |
568 | SSH_PRNG_SEED_FILE); | |
569 | ||
570 | debug("writing PRNG seed to file %.100s", filename); | |
571 | ||
572 | RAND_bytes(seed, sizeof(seed)); | |
573 | ||
574 | /* Don't care if the seed doesn't exist */ | |
575 | prng_check_seedfile(filename); | |
576 | ||
5b2d4b75 | 577 | if ((fd = open(filename, O_WRONLY|O_TRUNC|O_CREAT, 0600)) == -1) { |
578 | debug("WARNING: couldn't access PRNG seedfile %.100s (%.100s)", | |
579 | filename, strerror(errno)); | |
580 | } else { | |
581 | if (atomicio(write, fd, &seed, sizeof(seed)) != sizeof(seed)) | |
582 | fatal("problem writing PRNG seedfile %.100s (%.100s)", filename, | |
583 | strerror(errno)); | |
b7a87eea | 584 | |
5b2d4b75 | 585 | close(fd); |
586 | } | |
b7a87eea | 587 | } |
588 | ||
589 | void | |
590 | prng_read_seedfile(void) { | |
591 | int fd; | |
592 | char seed[1024]; | |
593 | char filename[1024]; | |
594 | struct passwd *pw; | |
595 | ||
264dce47 | 596 | pw = getpwuid(original_uid); |
b7a87eea | 597 | if (pw == NULL) |
598 | fatal("Couldn't get password entry for current user (%i): %s", | |
264dce47 | 599 | original_uid, strerror(errno)); |
b7a87eea | 600 | |
601 | snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir, | |
602 | SSH_PRNG_SEED_FILE); | |
603 | ||
604 | debug("loading PRNG seed from file %.100s", filename); | |
605 | ||
606 | if (!prng_check_seedfile(filename)) { | |
52ce34a2 | 607 | verbose("Random seed file not found or not valid, ignoring."); |
b7a87eea | 608 | return; |
609 | } | |
610 | ||
611 | /* open the file and read in the seed */ | |
612 | fd = open(filename, O_RDONLY); | |
613 | if (fd == -1) | |
614 | fatal("could not open PRNG seedfile %.100s (%.100s)", filename, | |
615 | strerror(errno)); | |
616 | ||
617 | if (atomicio(read, fd, &seed, sizeof(seed)) != sizeof(seed)) { | |
618 | verbose("invalid or short read from PRNG seedfile %.100s - ignoring", | |
619 | filename); | |
620 | memset(seed, '\0', sizeof(seed)); | |
621 | } | |
622 | close(fd); | |
623 | ||
624 | /* stir in the seed, with estimated entropy zero */ | |
625 | RAND_add(&seed, sizeof(seed), 0.0); | |
bfc9a610 | 626 | } |
b7a87eea | 627 | |
d3083fbd | 628 | |
629 | /* | |
630 | * entropy command initialisation functions | |
631 | */ | |
d3083fbd | 632 | int |
633 | prng_read_commands(char *cmdfilename) | |
634 | { | |
635 | FILE *f; | |
d3083fbd | 636 | char *cp; |
48c99b2c | 637 | char line[1024]; |
638 | char cmd[1024]; | |
639 | char path[256]; | |
d3083fbd | 640 | int linenum; |
d3083fbd | 641 | int num_cmds = 64; |
642 | int cur_cmd = 0; | |
48c99b2c | 643 | double est; |
644 | entropy_source_t *entcmd; | |
d3083fbd | 645 | |
646 | f = fopen(cmdfilename, "r"); | |
647 | if (!f) { | |
648 | fatal("couldn't read entropy commands file %.100s: %.100s", | |
649 | cmdfilename, strerror(errno)); | |
650 | } | |
651 | ||
d3083fbd | 652 | entcmd = (entropy_source_t *)xmalloc(num_cmds * sizeof(entropy_source_t)); |
653 | memset(entcmd, '\0', num_cmds * sizeof(entropy_source_t)); | |
654 | ||
48c99b2c | 655 | /* Read in file */ |
656 | linenum = 0; | |
d3083fbd | 657 | while (fgets(line, sizeof(line), f)) { |
48c99b2c | 658 | int arg; |
659 | char *argv; | |
660 | ||
d3083fbd | 661 | linenum++; |
662 | ||
663 | /* skip leading whitespace, test for blank line or comment */ | |
664 | cp = line + strspn(line, WHITESPACE); | |
665 | if ((*cp == 0) || (*cp == '#')) | |
666 | continue; /* done with this line */ | |
667 | ||
48c99b2c | 668 | /* First non-whitespace char should be double quote delimiting */ |
669 | /* commandline */ | |
670 | if (*cp != '"') { | |
671 | error("bad entropy command, %.100s line %d", cmdfilename, | |
672 | linenum); | |
673 | continue; | |
674 | } | |
d3083fbd | 675 | |
48c99b2c | 676 | /* first token, command args (incl. argv[0]) in double quotes */ |
677 | cp = strtok(cp, "\""); | |
678 | if (cp == NULL) { | |
679 | error("missing or bad command string, %.100s line %d -- ignored", | |
680 | cmdfilename, linenum); | |
681 | continue; | |
682 | } | |
683 | strlcpy(cmd, cp, sizeof(cmd)); | |
684 | ||
685 | /* second token, full command path */ | |
686 | if ((cp = strtok(NULL, WHITESPACE)) == NULL) { | |
687 | error("missing command path, %.100s line %d -- ignored", | |
688 | cmdfilename, linenum); | |
689 | continue; | |
690 | } | |
d3083fbd | 691 | |
48c99b2c | 692 | /* did configure mark this as dead? */ |
693 | if (strncmp("undef", cp, 5) == 0) | |
694 | continue; | |
d3083fbd | 695 | |
48c99b2c | 696 | strlcpy(path, cp, sizeof(path)); |
697 | ||
698 | /* third token, entropy rate estimate for this command */ | |
699 | if ((cp = strtok(NULL, WHITESPACE)) == NULL) { | |
700 | error("missing entropy estimate, %.100s line %d -- ignored", | |
701 | cmdfilename, linenum); | |
702 | continue; | |
703 | } | |
704 | est = strtod(cp, &argv); | |
705 | ||
706 | /* end of line */ | |
707 | if ((cp = strtok(NULL, WHITESPACE)) != NULL) { | |
708 | error("garbage at end of line %d in %.100s -- ignored", linenum, | |
709 | cmdfilename); | |
d3083fbd | 710 | continue; |
711 | } | |
48c99b2c | 712 | |
713 | /* save the command for debug messages */ | |
714 | entcmd[cur_cmd].cmdstring = xstrdup(cmd); | |
715 | ||
716 | /* split the command args */ | |
717 | cp = strtok(cmd, WHITESPACE); | |
718 | arg = 0; | |
719 | argv = NULL; | |
720 | do { | |
721 | char *s = (char*)xmalloc(strlen(cp) + 1); | |
722 | strncpy(s, cp, strlen(cp) + 1); | |
723 | entcmd[cur_cmd].args[arg] = s; | |
724 | arg++; | |
725 | } while ((arg < 5) && (cp = strtok(NULL, WHITESPACE))); | |
726 | ||
727 | if (strtok(NULL, WHITESPACE)) | |
728 | error("ignored extra command elements (max 5), %.100s line %d", | |
729 | cmdfilename, linenum); | |
730 | ||
731 | /* Copy the command path and rate estimate */ | |
732 | entcmd[cur_cmd].path = xstrdup(path); | |
733 | entcmd[cur_cmd].rate = est; | |
734 | ||
735 | /* Initialise other values */ | |
736 | entcmd[cur_cmd].sticky_badness = 1; | |
737 | ||
738 | cur_cmd++; | |
739 | ||
740 | /* If we've filled the array, reallocate it twice the size */ | |
741 | /* Do this now because even if this we're on the last command, | |
742 | we need another slot to mark the last entry */ | |
743 | if (cur_cmd == num_cmds) { | |
744 | num_cmds *= 2; | |
745 | entcmd = xrealloc(entcmd, num_cmds * sizeof(entropy_source_t)); | |
746 | } | |
d3083fbd | 747 | } |
748 | ||
749 | /* zero the last entry */ | |
750 | memset(&entcmd[cur_cmd], '\0', sizeof(entropy_source_t)); | |
48c99b2c | 751 | |
d3083fbd | 752 | /* trim to size */ |
753 | entropy_sources = xrealloc(entcmd, (cur_cmd+1) * sizeof(entropy_source_t)); | |
754 | ||
264dce47 | 755 | debug("Loaded %d entropy commands from %.100s", cur_cmd, cmdfilename); |
d3083fbd | 756 | |
757 | return (cur_cmd >= MIN_ENTROPY_SOURCES); | |
758 | } | |
759 | ||
b7a87eea | 760 | /* |
761 | * Write a keyfile at exit | |
762 | */ | |
763 | void | |
764 | prng_seed_cleanup(void *junk) | |
765 | { | |
766 | prng_write_seedfile(); | |
767 | } | |
768 | ||
bfc9a610 | 769 | /* |
b7a87eea | 770 | * Conditionally Seed OpenSSL's random number pool from |
771 | * syscalls and program output | |
bfc9a610 | 772 | */ |
773 | void | |
774 | seed_rng(void) | |
775 | { | |
a64009ad | 776 | void *old_sigchld_handler; |
d3083fbd | 777 | |
264dce47 | 778 | if (!prng_initialised) |
779 | fatal("RNG not initialised"); | |
780 | ||
a64009ad | 781 | /* Make sure some other sigchld handler doesn't reap our entropy */ |
782 | /* commands */ | |
783 | old_sigchld_handler = signal(SIGCHLD, SIG_DFL); | |
784 | ||
264dce47 | 785 | debug("Seeded RNG with %i bytes from programs", (int)stir_from_programs()); |
786 | debug("Seeded RNG with %i bytes from system calls", (int)stir_from_system()); | |
787 | ||
788 | if (!RAND_status()) | |
789 | fatal("Not enough entropy in RNG"); | |
b7a87eea | 790 | |
a64009ad | 791 | signal(SIGCHLD, old_sigchld_handler); |
792 | ||
ad85db64 | 793 | if (!RAND_status()) |
794 | fatal("Couldn't initialise builtin random number generator -- exiting."); | |
264dce47 | 795 | } |
ad85db64 | 796 | |
264dce47 | 797 | void init_rng(void) |
798 | { | |
e879a080 | 799 | int original_euid; |
800 | ||
264dce47 | 801 | original_uid = getuid(); |
e879a080 | 802 | original_euid = geteuid(); |
264dce47 | 803 | |
804 | /* Read in collection commands */ | |
805 | if (!prng_read_commands(SSH_PRNG_COMMAND_FILE)) | |
806 | fatal("PRNG initialisation failed -- exiting."); | |
807 | ||
808 | /* Set ourselves up to save a seed upon exit */ | |
809 | prng_seed_saved = 0; | |
e879a080 | 810 | |
811 | /* Give up privs while reading seed file */ | |
812 | if ((original_uid != original_euid) && (seteuid(original_uid) == -1)) | |
813 | fatal("Couldn't give up privileges"); | |
814 | ||
264dce47 | 815 | prng_read_seedfile(); |
e879a080 | 816 | |
817 | if ((original_uid != original_euid) && (seteuid(original_euid) == -1)) | |
818 | fatal("Couldn't restore privileges"); | |
819 | ||
264dce47 | 820 | fatal_add_cleanup(prng_seed_cleanup, NULL); |
821 | atexit(prng_write_seedfile); | |
822 | ||
823 | prng_initialised = 1; | |
bfc9a610 | 824 | } |
264dce47 | 825 | |
bfc9a610 | 826 | #endif /* defined(EGD_SOCKET) || defined(RANDOM_POOL) */ |