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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 | * | |
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 <openssl/rand.h> | |
28 | #include <openssl/sha.h> | |
29 | ||
30 | /* SunOS 4.4.4 needs this */ | |
31 | #ifdef HAVE_FLOATINGPOINT_H | |
32 | # include <floatingpoint.h> | |
33 | #endif /* HAVE_FLOATINGPOINT_H */ | |
34 | ||
35 | #include "ssh.h" | |
36 | #include "xmalloc.h" | |
37 | #include "atomicio.h" | |
38 | #include "pathnames.h" | |
39 | #include "log.h" | |
40 | ||
41 | RCSID("$Id$"); | |
42 | ||
43 | #ifndef offsetof | |
44 | # define offsetof(type, member) ((size_t) &((type *)0)->member) | |
45 | #endif | |
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 | ||
58 | #ifndef RUSAGE_SELF | |
59 | # define RUSAGE_SELF 0 | |
60 | #endif | |
61 | #ifndef RUSAGE_CHILDREN | |
62 | # define RUSAGE_CHILDREN 0 | |
63 | #endif | |
64 | ||
65 | #if defined(EGD_SOCKET) || defined(RANDOM_POOL) | |
66 | ||
67 | #ifdef EGD_SOCKET | |
68 | /* Collect entropy from EGD */ | |
69 | int get_random_bytes(unsigned char *buf, int len) | |
70 | { | |
71 | int fd; | |
72 | char msg[2]; | |
73 | struct sockaddr_un addr; | |
74 | int addr_len, rval, errors; | |
75 | struct sigaction nsa, osa; | |
76 | ||
77 | /* Sanity checks */ | |
78 | if (sizeof(EGD_SOCKET) > sizeof(addr.sun_path)) | |
79 | fatal("Random pool path is too long"); | |
80 | if (len > 255) | |
81 | fatal("Too many bytes to read from EGD"); | |
82 | ||
83 | memset(&addr, '\0', sizeof(addr)); | |
84 | addr.sun_family = AF_UNIX; | |
85 | strlcpy(addr.sun_path, EGD_SOCKET, sizeof(addr.sun_path)); | |
86 | addr_len = offsetof(struct sockaddr_un, sun_path) + sizeof(EGD_SOCKET); | |
87 | ||
88 | memset(&nsa, 0, sizeof(nsa)); | |
89 | nsa.sa_handler = SIG_IGN; | |
90 | (void) sigaction(SIGPIPE, &nsa, &osa); | |
91 | ||
92 | errors = rval = 0; | |
93 | reopen: | |
94 | fd = socket(AF_UNIX, SOCK_STREAM, 0); | |
95 | if (fd == -1) { | |
96 | error("Couldn't create AF_UNIX socket: %s", strerror(errno)); | |
97 | goto done; | |
98 | } | |
99 | ||
100 | if (connect(fd, (struct sockaddr*)&addr, addr_len) == -1) { | |
101 | error("Couldn't connect to EGD socket \"%s\": %s", | |
102 | addr.sun_path, strerror(errno)); | |
103 | goto done; | |
104 | } | |
105 | ||
106 | /* Send blocking read request to EGD */ | |
107 | msg[0] = 0x02; | |
108 | msg[1] = len; | |
109 | ||
110 | if (atomicio(write, fd, msg, sizeof(msg)) != sizeof(msg)) { | |
111 | if (errno == EPIPE && errors < 10) { | |
112 | close(fd); | |
113 | errors++; | |
114 | goto reopen; | |
115 | } | |
116 | error("Couldn't write to EGD socket \"%s\": %s", | |
117 | EGD_SOCKET, strerror(errno)); | |
118 | goto done; | |
119 | } | |
120 | ||
121 | if (atomicio(read, fd, buf, len) != len) { | |
122 | if (errno == EPIPE && errors < 10) { | |
123 | close(fd); | |
124 | errors++; | |
125 | goto reopen; | |
126 | } | |
127 | error("Couldn't read from EGD socket \"%s\": %s", | |
128 | EGD_SOCKET, strerror(errno)); | |
129 | goto done; | |
130 | } | |
131 | ||
132 | rval = 1; | |
133 | done: | |
134 | (void) sigaction(SIGPIPE, &osa, NULL); | |
135 | if (fd != -1) | |
136 | close(fd); | |
137 | return(rval); | |
138 | } | |
139 | #else /* !EGD_SOCKET */ | |
140 | #ifdef RANDOM_POOL | |
141 | /* Collect entropy from /dev/urandom or pipe */ | |
142 | int get_random_bytes(unsigned char *buf, int len) | |
143 | { | |
144 | int random_pool; | |
145 | ||
146 | random_pool = open(RANDOM_POOL, O_RDONLY); | |
147 | if (random_pool == -1) { | |
148 | error("Couldn't open random pool \"%s\": %s", | |
149 | RANDOM_POOL, strerror(errno)); | |
150 | return(0); | |
151 | } | |
152 | ||
153 | if (atomicio(read, random_pool, buf, len) != len) { | |
154 | error("Couldn't read from random pool \"%s\": %s", | |
155 | RANDOM_POOL, strerror(errno)); | |
156 | close(random_pool); | |
157 | return(0); | |
158 | } | |
159 | ||
160 | close(random_pool); | |
161 | ||
162 | return(1); | |
163 | } | |
164 | #endif /* RANDOM_POOL */ | |
165 | #endif /* EGD_SOCKET */ | |
166 | ||
167 | /* | |
168 | * Seed OpenSSL's random number pool from Kernel random number generator | |
169 | * or EGD | |
170 | */ | |
171 | void | |
172 | seed_rng(void) | |
173 | { | |
174 | char buf[32]; | |
175 | ||
176 | debug("Seeding random number generator"); | |
177 | ||
178 | if (!get_random_bytes(buf, sizeof(buf))) { | |
179 | if (!RAND_status()) | |
180 | fatal("Entropy collection failed and entropy exhausted"); | |
181 | } else { | |
182 | RAND_add(buf, sizeof(buf), sizeof(buf)); | |
183 | } | |
184 | ||
185 | memset(buf, '\0', sizeof(buf)); | |
186 | } | |
187 | ||
188 | /* No-op */ | |
189 | void init_rng(void) {} | |
190 | ||
191 | #else /* defined(EGD_SOCKET) || defined(RANDOM_POOL) */ | |
192 | ||
193 | /* | |
194 | * FIXME: proper entropy estimations. All current values are guesses | |
195 | * FIXME: (ATL) do estimates at compile time? | |
196 | * FIXME: More entropy sources | |
197 | */ | |
198 | ||
199 | /* slow command timeouts (all in milliseconds) */ | |
200 | /* static int entropy_timeout_default = ENTROPY_TIMEOUT_MSEC; */ | |
201 | static int entropy_timeout_current = ENTROPY_TIMEOUT_MSEC; | |
202 | ||
203 | static int prng_seed_saved = 0; | |
204 | static int prng_initialised = 0; | |
205 | uid_t original_uid; | |
206 | ||
207 | typedef struct | |
208 | { | |
209 | /* Proportion of data that is entropy */ | |
210 | double rate; | |
211 | /* Counter goes positive if this command times out */ | |
212 | unsigned int badness; | |
213 | /* Increases by factor of two each timeout */ | |
214 | unsigned int sticky_badness; | |
215 | /* Path to executable */ | |
216 | char *path; | |
217 | /* argv to pass to executable */ | |
218 | char *args[5]; | |
219 | /* full command string (debug) */ | |
220 | char *cmdstring; | |
221 | } entropy_source_t; | |
222 | ||
223 | double stir_from_system(void); | |
224 | double stir_from_programs(void); | |
225 | double stir_gettimeofday(double entropy_estimate); | |
226 | double stir_clock(double entropy_estimate); | |
227 | double stir_rusage(int who, double entropy_estimate); | |
228 | double hash_output_from_command(entropy_source_t *src, char *hash); | |
229 | ||
230 | /* this is initialised from a file, by prng_read_commands() */ | |
231 | entropy_source_t *entropy_sources = NULL; | |
232 | ||
233 | double | |
234 | stir_from_system(void) | |
235 | { | |
236 | double total_entropy_estimate; | |
237 | long int i; | |
238 | ||
239 | total_entropy_estimate = 0; | |
240 | ||
241 | i = getpid(); | |
242 | RAND_add(&i, sizeof(i), 0.5); | |
243 | total_entropy_estimate += 0.1; | |
244 | ||
245 | i = getppid(); | |
246 | RAND_add(&i, sizeof(i), 0.5); | |
247 | total_entropy_estimate += 0.1; | |
248 | ||
249 | i = getuid(); | |
250 | RAND_add(&i, sizeof(i), 0.0); | |
251 | i = getgid(); | |
252 | RAND_add(&i, sizeof(i), 0.0); | |
253 | ||
254 | total_entropy_estimate += stir_gettimeofday(1.0); | |
255 | total_entropy_estimate += stir_clock(0.5); | |
256 | total_entropy_estimate += stir_rusage(RUSAGE_SELF, 2.0); | |
257 | ||
258 | return(total_entropy_estimate); | |
259 | } | |
260 | ||
261 | double | |
262 | stir_from_programs(void) | |
263 | { | |
264 | int i; | |
265 | int c; | |
266 | double entropy_estimate; | |
267 | double total_entropy_estimate; | |
268 | char hash[SHA_DIGEST_LENGTH]; | |
269 | ||
270 | total_entropy_estimate = 0; | |
271 | for(i = 0; i < NUM_ENTROPY_RUNS; i++) { | |
272 | c = 0; | |
273 | while (entropy_sources[c].path != NULL) { | |
274 | ||
275 | if (!entropy_sources[c].badness) { | |
276 | /* Hash output from command */ | |
277 | entropy_estimate = hash_output_from_command(&entropy_sources[c], hash); | |
278 | ||
279 | /* Scale back entropy estimate according to command's rate */ | |
280 | entropy_estimate *= entropy_sources[c].rate; | |
281 | ||
282 | /* Upper bound of entropy estimate is SHA_DIGEST_LENGTH */ | |
283 | if (entropy_estimate > SHA_DIGEST_LENGTH) | |
284 | entropy_estimate = SHA_DIGEST_LENGTH; | |
285 | ||
286 | /* Scale back estimates for subsequent passes through list */ | |
287 | entropy_estimate /= SCALE_PER_RUN * (i + 1.0); | |
288 | ||
289 | /* Stir it in */ | |
290 | RAND_add(hash, sizeof(hash), entropy_estimate); | |
291 | ||
292 | debug3("Got %0.2f bytes of entropy from '%s'", entropy_estimate, | |
293 | entropy_sources[c].cmdstring); | |
294 | ||
295 | total_entropy_estimate += entropy_estimate; | |
296 | ||
297 | /* Execution times should be a little unpredictable */ | |
298 | total_entropy_estimate += stir_gettimeofday(0.05); | |
299 | total_entropy_estimate += stir_clock(0.05); | |
300 | total_entropy_estimate += stir_rusage(RUSAGE_SELF, 0.1); | |
301 | total_entropy_estimate += stir_rusage(RUSAGE_CHILDREN, 0.1); | |
302 | } else { | |
303 | debug2("Command '%s' disabled (badness %d)", | |
304 | entropy_sources[c].cmdstring, entropy_sources[c].badness); | |
305 | ||
306 | if (entropy_sources[c].badness > 0) | |
307 | entropy_sources[c].badness--; | |
308 | } | |
309 | ||
310 | c++; | |
311 | } | |
312 | } | |
313 | ||
314 | return(total_entropy_estimate); | |
315 | } | |
316 | ||
317 | double | |
318 | stir_gettimeofday(double entropy_estimate) | |
319 | { | |
320 | struct timeval tv; | |
321 | ||
322 | if (gettimeofday(&tv, NULL) == -1) | |
323 | fatal("Couldn't gettimeofday: %s", strerror(errno)); | |
324 | ||
325 | RAND_add(&tv, sizeof(tv), entropy_estimate); | |
326 | ||
327 | return(entropy_estimate); | |
328 | } | |
329 | ||
330 | double | |
331 | stir_clock(double entropy_estimate) | |
332 | { | |
333 | #ifdef HAVE_CLOCK | |
334 | clock_t c; | |
335 | ||
336 | c = clock(); | |
337 | RAND_add(&c, sizeof(c), entropy_estimate); | |
338 | ||
339 | return(entropy_estimate); | |
340 | #else /* _HAVE_CLOCK */ | |
341 | return(0); | |
342 | #endif /* _HAVE_CLOCK */ | |
343 | } | |
344 | ||
345 | double | |
346 | stir_rusage(int who, double entropy_estimate) | |
347 | { | |
348 | #ifdef HAVE_GETRUSAGE | |
349 | struct rusage ru; | |
350 | ||
351 | if (getrusage(who, &ru) == -1) | |
352 | return(0); | |
353 | ||
354 | RAND_add(&ru, sizeof(ru), entropy_estimate); | |
355 | ||
356 | return(entropy_estimate); | |
357 | #else /* _HAVE_GETRUSAGE */ | |
358 | return(0); | |
359 | #endif /* _HAVE_GETRUSAGE */ | |
360 | } | |
361 | ||
362 | ||
363 | static | |
364 | int | |
365 | _get_timeval_msec_difference(struct timeval *t1, struct timeval *t2) { | |
366 | int secdiff, usecdiff; | |
367 | ||
368 | secdiff = t2->tv_sec - t1->tv_sec; | |
369 | usecdiff = (secdiff*1000000) + (t2->tv_usec - t1->tv_usec); | |
370 | return (int)(usecdiff / 1000); | |
371 | } | |
372 | ||
373 | double | |
374 | hash_output_from_command(entropy_source_t *src, char *hash) | |
375 | { | |
376 | static int devnull = -1; | |
377 | int p[2]; | |
378 | fd_set rdset; | |
379 | int cmd_eof = 0, error_abort = 0; | |
380 | struct timeval tv_start, tv_current; | |
381 | int msec_elapsed = 0; | |
382 | pid_t pid; | |
383 | int status; | |
384 | char buf[16384]; | |
385 | int bytes_read; | |
386 | int total_bytes_read; | |
387 | SHA_CTX sha; | |
388 | ||
389 | debug3("Reading output from \'%s\'", src->cmdstring); | |
390 | ||
391 | if (devnull == -1) { | |
392 | devnull = open("/dev/null", O_RDWR); | |
393 | if (devnull == -1) | |
394 | fatal("Couldn't open /dev/null: %s", strerror(errno)); | |
395 | } | |
396 | ||
397 | if (pipe(p) == -1) | |
398 | fatal("Couldn't open pipe: %s", strerror(errno)); | |
399 | ||
400 | (void)gettimeofday(&tv_start, NULL); /* record start time */ | |
401 | ||
402 | switch (pid = fork()) { | |
403 | case -1: /* Error */ | |
404 | close(p[0]); | |
405 | close(p[1]); | |
406 | fatal("Couldn't fork: %s", strerror(errno)); | |
407 | /* NOTREACHED */ | |
408 | case 0: /* Child */ | |
409 | dup2(devnull, STDIN_FILENO); | |
410 | dup2(p[1], STDOUT_FILENO); | |
411 | dup2(p[1], STDERR_FILENO); | |
412 | close(p[0]); | |
413 | close(p[1]); | |
414 | close(devnull); | |
415 | ||
416 | setuid(original_uid); | |
417 | execv(src->path, (char**)(src->args)); | |
418 | debug("(child) Couldn't exec '%s': %s", src->cmdstring, | |
419 | strerror(errno)); | |
420 | _exit(-1); | |
421 | default: /* Parent */ | |
422 | break; | |
423 | } | |
424 | ||
425 | RAND_add(&pid, sizeof(&pid), 0.0); | |
426 | ||
427 | close(p[1]); | |
428 | ||
429 | /* Hash output from child */ | |
430 | SHA1_Init(&sha); | |
431 | total_bytes_read = 0; | |
432 | ||
433 | while (!error_abort && !cmd_eof) { | |
434 | int ret; | |
435 | struct timeval tv; | |
436 | int msec_remaining; | |
437 | ||
438 | (void) gettimeofday(&tv_current, 0); | |
439 | msec_elapsed = _get_timeval_msec_difference(&tv_start, &tv_current); | |
440 | if (msec_elapsed >= entropy_timeout_current) { | |
441 | error_abort=1; | |
442 | continue; | |
443 | } | |
444 | msec_remaining = entropy_timeout_current - msec_elapsed; | |
445 | ||
446 | FD_ZERO(&rdset); | |
447 | FD_SET(p[0], &rdset); | |
448 | tv.tv_sec = msec_remaining / 1000; | |
449 | tv.tv_usec = (msec_remaining % 1000) * 1000; | |
450 | ||
451 | ret = select(p[0]+1, &rdset, NULL, NULL, &tv); | |
452 | ||
453 | RAND_add(&tv, sizeof(tv), 0.0); | |
454 | ||
455 | switch (ret) { | |
456 | case 0: | |
457 | /* timer expired */ | |
458 | error_abort = 1; | |
459 | break; | |
460 | case 1: | |
461 | /* command input */ | |
462 | bytes_read = read(p[0], buf, sizeof(buf)); | |
463 | RAND_add(&bytes_read, sizeof(&bytes_read), 0.0); | |
464 | if (bytes_read == -1) { | |
465 | error_abort = 1; | |
466 | break; | |
467 | } else if (bytes_read) { | |
468 | SHA1_Update(&sha, buf, bytes_read); | |
469 | total_bytes_read += bytes_read; | |
470 | } else { | |
471 | cmd_eof = 1; | |
472 | } | |
473 | break; | |
474 | case -1: | |
475 | default: | |
476 | /* error */ | |
477 | debug("Command '%s': select() failed: %s", src->cmdstring, | |
478 | strerror(errno)); | |
479 | error_abort = 1; | |
480 | break; | |
481 | } | |
482 | } | |
483 | ||
484 | SHA1_Final(hash, &sha); | |
485 | ||
486 | close(p[0]); | |
487 | ||
488 | debug3("Time elapsed: %d msec", msec_elapsed); | |
489 | ||
490 | if (waitpid(pid, &status, 0) == -1) { | |
491 | error("Couldn't wait for child '%s' completion: %s", src->cmdstring, | |
492 | strerror(errno)); | |
493 | return(0.0); | |
494 | } | |
495 | ||
496 | RAND_add(&status, sizeof(&status), 0.0); | |
497 | ||
498 | if (error_abort) { | |
499 | /* closing p[0] on timeout causes the entropy command to | |
500 | * SIGPIPE. Take whatever output we got, and mark this command | |
501 | * as slow */ | |
502 | debug2("Command '%s' timed out", src->cmdstring); | |
503 | src->sticky_badness *= 2; | |
504 | src->badness = src->sticky_badness; | |
505 | return(total_bytes_read); | |
506 | } | |
507 | ||
508 | if (WIFEXITED(status)) { | |
509 | if (WEXITSTATUS(status)==0) { | |
510 | return(total_bytes_read); | |
511 | } else { | |
512 | debug2("Command '%s' exit status was %d", src->cmdstring, | |
513 | WEXITSTATUS(status)); | |
514 | src->badness = src->sticky_badness = 128; | |
515 | return (0.0); | |
516 | } | |
517 | } else if (WIFSIGNALED(status)) { | |
518 | debug2("Command '%s' returned on uncaught signal %d !", src->cmdstring, | |
519 | status); | |
520 | src->badness = src->sticky_badness = 128; | |
521 | return(0.0); | |
522 | } else | |
523 | return(0.0); | |
524 | } | |
525 | ||
526 | /* | |
527 | * prng seedfile functions | |
528 | */ | |
529 | int | |
530 | prng_check_seedfile(char *filename) { | |
531 | ||
532 | struct stat st; | |
533 | ||
534 | /* FIXME raceable: eg replace seed between this stat and subsequent open */ | |
535 | /* Not such a problem because we don't trust the seed file anyway */ | |
536 | if (lstat(filename, &st) == -1) { | |
537 | /* Give up on hard errors */ | |
538 | if (errno != ENOENT) | |
539 | debug("WARNING: Couldn't stat random seed file \"%s\": %s", | |
540 | filename, strerror(errno)); | |
541 | ||
542 | return(0); | |
543 | } | |
544 | ||
545 | /* regular file? */ | |
546 | if (!S_ISREG(st.st_mode)) | |
547 | fatal("PRNG seedfile %.100s is not a regular file", filename); | |
548 | ||
549 | /* mode 0600, owned by root or the current user? */ | |
550 | if (((st.st_mode & 0177) != 0) || !(st.st_uid == original_uid)) { | |
551 | debug("WARNING: PRNG seedfile %.100s must be mode 0600, owned by uid %d", | |
552 | filename, getuid()); | |
553 | return(0); | |
554 | } | |
555 | ||
556 | return(1); | |
557 | } | |
558 | ||
559 | void | |
560 | prng_write_seedfile(void) { | |
561 | int fd; | |
562 | char seed[1024]; | |
563 | char filename[1024]; | |
564 | struct passwd *pw; | |
565 | ||
566 | /* Don't bother if we have already saved a seed */ | |
567 | if (prng_seed_saved) | |
568 | return; | |
569 | ||
570 | setuid(original_uid); | |
571 | ||
572 | prng_seed_saved = 1; | |
573 | ||
574 | pw = getpwuid(original_uid); | |
575 | if (pw == NULL) | |
576 | fatal("Couldn't get password entry for current user (%i): %s", | |
577 | original_uid, strerror(errno)); | |
578 | ||
579 | /* Try to ensure that the parent directory is there */ | |
580 | snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir, | |
581 | _PATH_SSH_USER_DIR); | |
582 | mkdir(filename, 0700); | |
583 | ||
584 | snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir, | |
585 | SSH_PRNG_SEED_FILE); | |
586 | ||
587 | debug("writing PRNG seed to file %.100s", filename); | |
588 | ||
589 | RAND_bytes(seed, sizeof(seed)); | |
590 | ||
591 | /* Don't care if the seed doesn't exist */ | |
592 | prng_check_seedfile(filename); | |
593 | ||
594 | if ((fd = open(filename, O_WRONLY|O_TRUNC|O_CREAT, 0600)) == -1) { | |
595 | debug("WARNING: couldn't access PRNG seedfile %.100s (%.100s)", | |
596 | filename, strerror(errno)); | |
597 | } else { | |
598 | if (atomicio(write, fd, &seed, sizeof(seed)) != sizeof(seed)) | |
599 | fatal("problem writing PRNG seedfile %.100s (%.100s)", filename, | |
600 | strerror(errno)); | |
601 | ||
602 | close(fd); | |
603 | } | |
604 | } | |
605 | ||
606 | void | |
607 | prng_read_seedfile(void) { | |
608 | int fd; | |
609 | char seed[1024]; | |
610 | char filename[1024]; | |
611 | struct passwd *pw; | |
612 | ||
613 | pw = getpwuid(original_uid); | |
614 | if (pw == NULL) | |
615 | fatal("Couldn't get password entry for current user (%i): %s", | |
616 | original_uid, strerror(errno)); | |
617 | ||
618 | snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir, | |
619 | SSH_PRNG_SEED_FILE); | |
620 | ||
621 | debug("loading PRNG seed from file %.100s", filename); | |
622 | ||
623 | if (!prng_check_seedfile(filename)) { | |
624 | verbose("Random seed file not found or not valid, ignoring."); | |
625 | return; | |
626 | } | |
627 | ||
628 | /* open the file and read in the seed */ | |
629 | fd = open(filename, O_RDONLY); | |
630 | if (fd == -1) | |
631 | fatal("could not open PRNG seedfile %.100s (%.100s)", filename, | |
632 | strerror(errno)); | |
633 | ||
634 | if (atomicio(read, fd, &seed, sizeof(seed)) != sizeof(seed)) { | |
635 | verbose("invalid or short read from PRNG seedfile %.100s - ignoring", | |
636 | filename); | |
637 | memset(seed, '\0', sizeof(seed)); | |
638 | } | |
639 | close(fd); | |
640 | ||
641 | /* stir in the seed, with estimated entropy zero */ | |
642 | RAND_add(&seed, sizeof(seed), 0.0); | |
643 | } | |
644 | ||
645 | ||
646 | /* | |
647 | * entropy command initialisation functions | |
648 | */ | |
649 | int | |
650 | prng_read_commands(char *cmdfilename) | |
651 | { | |
652 | FILE *f; | |
653 | char *cp; | |
654 | char line[1024]; | |
655 | char cmd[1024]; | |
656 | char path[256]; | |
657 | int linenum; | |
658 | int num_cmds = 64; | |
659 | int cur_cmd = 0; | |
660 | double est; | |
661 | entropy_source_t *entcmd; | |
662 | ||
663 | f = fopen(cmdfilename, "r"); | |
664 | if (!f) { | |
665 | fatal("couldn't read entropy commands file %.100s: %.100s", | |
666 | cmdfilename, strerror(errno)); | |
667 | } | |
668 | ||
669 | entcmd = (entropy_source_t *)xmalloc(num_cmds * sizeof(entropy_source_t)); | |
670 | memset(entcmd, '\0', num_cmds * sizeof(entropy_source_t)); | |
671 | ||
672 | /* Read in file */ | |
673 | linenum = 0; | |
674 | while (fgets(line, sizeof(line), f)) { | |
675 | int arg; | |
676 | char *argv; | |
677 | ||
678 | linenum++; | |
679 | ||
680 | /* skip leading whitespace, test for blank line or comment */ | |
681 | cp = line + strspn(line, WHITESPACE); | |
682 | if ((*cp == 0) || (*cp == '#')) | |
683 | continue; /* done with this line */ | |
684 | ||
685 | /* First non-whitespace char should be double quote delimiting */ | |
686 | /* commandline */ | |
687 | if (*cp != '"') { | |
688 | error("bad entropy command, %.100s line %d", cmdfilename, | |
689 | linenum); | |
690 | continue; | |
691 | } | |
692 | ||
693 | /* first token, command args (incl. argv[0]) in double quotes */ | |
694 | cp = strtok(cp, "\""); | |
695 | if (cp == NULL) { | |
696 | error("missing or bad command string, %.100s line %d -- ignored", | |
697 | cmdfilename, linenum); | |
698 | continue; | |
699 | } | |
700 | strlcpy(cmd, cp, sizeof(cmd)); | |
701 | ||
702 | /* second token, full command path */ | |
703 | if ((cp = strtok(NULL, WHITESPACE)) == NULL) { | |
704 | error("missing command path, %.100s line %d -- ignored", | |
705 | cmdfilename, linenum); | |
706 | continue; | |
707 | } | |
708 | ||
709 | /* did configure mark this as dead? */ | |
710 | if (strncmp("undef", cp, 5) == 0) | |
711 | continue; | |
712 | ||
713 | strlcpy(path, cp, sizeof(path)); | |
714 | ||
715 | /* third token, entropy rate estimate for this command */ | |
716 | if ((cp = strtok(NULL, WHITESPACE)) == NULL) { | |
717 | error("missing entropy estimate, %.100s line %d -- ignored", | |
718 | cmdfilename, linenum); | |
719 | continue; | |
720 | } | |
721 | est = strtod(cp, &argv); | |
722 | ||
723 | /* end of line */ | |
724 | if ((cp = strtok(NULL, WHITESPACE)) != NULL) { | |
725 | error("garbage at end of line %d in %.100s -- ignored", linenum, | |
726 | cmdfilename); | |
727 | continue; | |
728 | } | |
729 | ||
730 | /* save the command for debug messages */ | |
731 | entcmd[cur_cmd].cmdstring = xstrdup(cmd); | |
732 | ||
733 | /* split the command args */ | |
734 | cp = strtok(cmd, WHITESPACE); | |
735 | arg = 0; | |
736 | argv = NULL; | |
737 | do { | |
738 | char *s = (char*)xmalloc(strlen(cp) + 1); | |
739 | strncpy(s, cp, strlen(cp) + 1); | |
740 | entcmd[cur_cmd].args[arg] = s; | |
741 | arg++; | |
742 | } while ((arg < 5) && (cp = strtok(NULL, WHITESPACE))); | |
743 | ||
744 | if (strtok(NULL, WHITESPACE)) | |
745 | error("ignored extra command elements (max 5), %.100s line %d", | |
746 | cmdfilename, linenum); | |
747 | ||
748 | /* Copy the command path and rate estimate */ | |
749 | entcmd[cur_cmd].path = xstrdup(path); | |
750 | entcmd[cur_cmd].rate = est; | |
751 | ||
752 | /* Initialise other values */ | |
753 | entcmd[cur_cmd].sticky_badness = 1; | |
754 | ||
755 | cur_cmd++; | |
756 | ||
757 | /* If we've filled the array, reallocate it twice the size */ | |
758 | /* Do this now because even if this we're on the last command, | |
759 | we need another slot to mark the last entry */ | |
760 | if (cur_cmd == num_cmds) { | |
761 | num_cmds *= 2; | |
762 | entcmd = xrealloc(entcmd, num_cmds * sizeof(entropy_source_t)); | |
763 | } | |
764 | } | |
765 | ||
766 | /* zero the last entry */ | |
767 | memset(&entcmd[cur_cmd], '\0', sizeof(entropy_source_t)); | |
768 | ||
769 | /* trim to size */ | |
770 | entropy_sources = xrealloc(entcmd, (cur_cmd+1) * sizeof(entropy_source_t)); | |
771 | ||
772 | debug("Loaded %d entropy commands from %.100s", cur_cmd, cmdfilename); | |
773 | ||
774 | return (cur_cmd >= MIN_ENTROPY_SOURCES); | |
775 | } | |
776 | ||
777 | /* | |
778 | * Write a keyfile at exit | |
779 | */ | |
780 | void | |
781 | prng_seed_cleanup(void *junk) | |
782 | { | |
783 | prng_write_seedfile(); | |
784 | } | |
785 | ||
786 | /* | |
787 | * Conditionally Seed OpenSSL's random number pool from | |
788 | * syscalls and program output | |
789 | */ | |
790 | void | |
791 | seed_rng(void) | |
792 | { | |
793 | void *old_sigchld_handler; | |
794 | ||
795 | if (!prng_initialised) | |
796 | fatal("RNG not initialised"); | |
797 | ||
798 | /* Make sure some other sigchld handler doesn't reap our entropy */ | |
799 | /* commands */ | |
800 | old_sigchld_handler = signal(SIGCHLD, SIG_DFL); | |
801 | ||
802 | debug("Seeded RNG with %i bytes from programs", (int)stir_from_programs()); | |
803 | debug("Seeded RNG with %i bytes from system calls", (int)stir_from_system()); | |
804 | ||
805 | if (!RAND_status()) | |
806 | fatal("Not enough entropy in RNG"); | |
807 | ||
808 | signal(SIGCHLD, old_sigchld_handler); | |
809 | ||
810 | if (!RAND_status()) | |
811 | fatal("Couldn't initialise builtin random number generator -- exiting."); | |
812 | } | |
813 | ||
814 | void init_rng(void) | |
815 | { | |
816 | int original_euid; | |
817 | ||
818 | original_uid = getuid(); | |
819 | original_euid = geteuid(); | |
820 | ||
821 | /* Read in collection commands */ | |
822 | if (!prng_read_commands(SSH_PRNG_COMMAND_FILE)) | |
823 | fatal("PRNG initialisation failed -- exiting."); | |
824 | ||
825 | /* Set ourselves up to save a seed upon exit */ | |
826 | prng_seed_saved = 0; | |
827 | ||
828 | /* Give up privs while reading seed file */ | |
829 | if ((original_uid != original_euid) && (seteuid(original_uid) == -1)) | |
830 | fatal("Couldn't give up privileges"); | |
831 | ||
832 | prng_read_seedfile(); | |
833 | ||
834 | if ((original_uid != original_euid) && (seteuid(original_euid) == -1)) | |
835 | fatal("Couldn't restore privileges"); | |
836 | ||
837 | fatal_add_cleanup(prng_seed_cleanup, NULL); | |
838 | atexit(prng_write_seedfile); | |
839 | ||
840 | prng_initialised = 1; | |
841 | } | |
842 | ||
843 | #endif /* defined(EGD_SOCKET) || defined(RANDOM_POOL) */ |