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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 | #include <openssl/crypto.h> | |
30 | ||
31 | /* SunOS 4.4.4 needs this */ | |
32 | #ifdef HAVE_FLOATINGPOINT_H | |
33 | # include <floatingpoint.h> | |
34 | #endif /* HAVE_FLOATINGPOINT_H */ | |
35 | ||
36 | #include "ssh.h" | |
37 | #include "misc.h" | |
38 | #include "xmalloc.h" | |
39 | #include "atomicio.h" | |
40 | #include "pathnames.h" | |
41 | #include "log.h" | |
42 | ||
43 | RCSID("$Id$"); | |
44 | ||
45 | #ifndef offsetof | |
46 | # define offsetof(type, member) ((size_t) &((type *)0)->member) | |
47 | #endif | |
48 | ||
49 | /* Number of times to pass through command list gathering entropy */ | |
50 | #define NUM_ENTROPY_RUNS 1 | |
51 | ||
52 | /* Scale entropy estimates back by this amount on subsequent runs */ | |
53 | #define SCALE_PER_RUN 10.0 | |
54 | ||
55 | /* Minimum number of commands to be considered valid */ | |
56 | #define MIN_ENTROPY_SOURCES 16 | |
57 | ||
58 | #define WHITESPACE " \t\n" | |
59 | ||
60 | #ifndef RUSAGE_SELF | |
61 | # define RUSAGE_SELF 0 | |
62 | #endif | |
63 | #ifndef RUSAGE_CHILDREN | |
64 | # define RUSAGE_CHILDREN 0 | |
65 | #endif | |
66 | ||
67 | #if defined(_POSIX_SAVED_IDS) && !defined(BROKEN_SAVED_UIDS) | |
68 | # define SAVED_IDS_WORK_WITH_SETEUID | |
69 | #endif | |
70 | ||
71 | void check_openssl_version(void) | |
72 | { | |
73 | if (SSLeay() != OPENSSL_VERSION_NUMBER) | |
74 | fatal("OpenSSL version mismatch. Built against %lx, you " | |
75 | "have %lx", OPENSSL_VERSION_NUMBER, SSLeay()); | |
76 | } | |
77 | ||
78 | #if defined(PRNGD_SOCKET) || defined(PRNGD_PORT) | |
79 | # define USE_PRNGD | |
80 | #endif | |
81 | ||
82 | #if defined(USE_PRNGD) || defined(RANDOM_POOL) | |
83 | ||
84 | #ifdef USE_PRNGD | |
85 | /* Collect entropy from PRNGD/EGD */ | |
86 | int get_random_bytes(unsigned char *buf, int len) | |
87 | { | |
88 | int fd; | |
89 | char msg[2]; | |
90 | #ifdef PRNGD_PORT | |
91 | struct sockaddr_in addr; | |
92 | #else | |
93 | struct sockaddr_un addr; | |
94 | #endif | |
95 | int addr_len, rval, errors; | |
96 | mysig_t old_sigpipe; | |
97 | ||
98 | memset(&addr, '\0', sizeof(addr)); | |
99 | ||
100 | #ifdef PRNGD_PORT | |
101 | addr.sin_family = AF_INET; | |
102 | addr.sin_addr.s_addr = htonl(INADDR_LOOPBACK); | |
103 | addr.sin_port = htons(PRNGD_PORT); | |
104 | addr_len = sizeof(struct sockaddr_in); | |
105 | #else /* use IP socket PRNGD_SOCKET instead */ | |
106 | /* Sanity checks */ | |
107 | if (sizeof(PRNGD_SOCKET) > sizeof(addr.sun_path)) | |
108 | fatal("Random pool path is too long"); | |
109 | if (len > 255) | |
110 | fatal("Too many bytes to read from PRNGD"); | |
111 | ||
112 | addr.sun_family = AF_UNIX; | |
113 | strlcpy(addr.sun_path, PRNGD_SOCKET, sizeof(addr.sun_path)); | |
114 | addr_len = offsetof(struct sockaddr_un, sun_path) + | |
115 | sizeof(PRNGD_SOCKET); | |
116 | #endif | |
117 | ||
118 | old_sigpipe = mysignal(SIGPIPE, SIG_IGN); | |
119 | ||
120 | errors = rval = 0; | |
121 | reopen: | |
122 | #ifdef PRNGD_PORT | |
123 | fd = socket(addr.sin_family, SOCK_STREAM, 0); | |
124 | if (fd == -1) { | |
125 | error("Couldn't create AF_INET socket: %s", strerror(errno)); | |
126 | goto done; | |
127 | } | |
128 | #else | |
129 | fd = socket(addr.sun_family, SOCK_STREAM, 0); | |
130 | if (fd == -1) { | |
131 | error("Couldn't create AF_UNIX socket: %s", strerror(errno)); | |
132 | goto done; | |
133 | } | |
134 | #endif | |
135 | ||
136 | if (connect(fd, (struct sockaddr*)&addr, addr_len) == -1) { | |
137 | #ifdef PRNGD_PORT | |
138 | error("Couldn't connect to PRNGD port %d: %s", | |
139 | PRNGD_PORT, strerror(errno)); | |
140 | #else | |
141 | error("Couldn't connect to PRNGD socket \"%s\": %s", | |
142 | addr.sun_path, strerror(errno)); | |
143 | #endif | |
144 | goto done; | |
145 | } | |
146 | ||
147 | /* Send blocking read request to PRNGD */ | |
148 | msg[0] = 0x02; | |
149 | msg[1] = len; | |
150 | ||
151 | if (atomicio(write, fd, msg, sizeof(msg)) != sizeof(msg)) { | |
152 | if (errno == EPIPE && errors < 10) { | |
153 | close(fd); | |
154 | errors++; | |
155 | goto reopen; | |
156 | } | |
157 | error("Couldn't write to PRNGD socket: %s", | |
158 | strerror(errno)); | |
159 | goto done; | |
160 | } | |
161 | ||
162 | if (atomicio(read, fd, buf, len) != len) { | |
163 | if (errno == EPIPE && errors < 10) { | |
164 | close(fd); | |
165 | errors++; | |
166 | goto reopen; | |
167 | } | |
168 | error("Couldn't read from PRNGD socket: %s", | |
169 | strerror(errno)); | |
170 | goto done; | |
171 | } | |
172 | ||
173 | rval = 1; | |
174 | done: | |
175 | mysignal(SIGPIPE, old_sigpipe); | |
176 | if (fd != -1) | |
177 | close(fd); | |
178 | return(rval); | |
179 | } | |
180 | #else /* !USE_PRNGD */ | |
181 | #ifdef RANDOM_POOL | |
182 | /* Collect entropy from /dev/urandom or pipe */ | |
183 | int get_random_bytes(unsigned char *buf, int len) | |
184 | { | |
185 | int random_pool; | |
186 | ||
187 | random_pool = open(RANDOM_POOL, O_RDONLY); | |
188 | if (random_pool == -1) { | |
189 | error("Couldn't open random pool \"%s\": %s", | |
190 | RANDOM_POOL, strerror(errno)); | |
191 | return(0); | |
192 | } | |
193 | ||
194 | if (atomicio(read, random_pool, buf, len) != len) { | |
195 | error("Couldn't read from random pool \"%s\": %s", | |
196 | RANDOM_POOL, strerror(errno)); | |
197 | close(random_pool); | |
198 | return(0); | |
199 | } | |
200 | ||
201 | close(random_pool); | |
202 | ||
203 | return(1); | |
204 | } | |
205 | #endif /* RANDOM_POOL */ | |
206 | #endif /* USE_PRNGD */ | |
207 | ||
208 | /* | |
209 | * Seed OpenSSL's random number pool from Kernel random number generator | |
210 | * or PRNGD/EGD | |
211 | */ | |
212 | void | |
213 | seed_rng(void) | |
214 | { | |
215 | unsigned char buf[32]; | |
216 | ||
217 | debug("Seeding random number generator"); | |
218 | ||
219 | if (!get_random_bytes(buf, sizeof(buf))) { | |
220 | if (!RAND_status()) | |
221 | fatal("Entropy collection failed and entropy exhausted"); | |
222 | } else { | |
223 | RAND_add(buf, sizeof(buf), sizeof(buf)); | |
224 | } | |
225 | ||
226 | memset(buf, '\0', sizeof(buf)); | |
227 | } | |
228 | ||
229 | void init_rng(void) | |
230 | { | |
231 | check_openssl_version(); | |
232 | } | |
233 | ||
234 | #else /* defined(USE_PRNGD) || defined(RANDOM_POOL) */ | |
235 | ||
236 | /* | |
237 | * FIXME: proper entropy estimations. All current values are guesses | |
238 | * FIXME: (ATL) do estimates at compile time? | |
239 | * FIXME: More entropy sources | |
240 | */ | |
241 | ||
242 | /* slow command timeouts (all in milliseconds) */ | |
243 | /* static int entropy_timeout_default = ENTROPY_TIMEOUT_MSEC; */ | |
244 | static int entropy_timeout_current = ENTROPY_TIMEOUT_MSEC; | |
245 | ||
246 | static int prng_seed_saved = 0; | |
247 | static int prng_initialised = 0; | |
248 | uid_t original_uid; | |
249 | ||
250 | typedef struct | |
251 | { | |
252 | /* Proportion of data that is entropy */ | |
253 | double rate; | |
254 | /* Counter goes positive if this command times out */ | |
255 | unsigned int badness; | |
256 | /* Increases by factor of two each timeout */ | |
257 | unsigned int sticky_badness; | |
258 | /* Path to executable */ | |
259 | char *path; | |
260 | /* argv to pass to executable */ | |
261 | char *args[5]; | |
262 | /* full command string (debug) */ | |
263 | char *cmdstring; | |
264 | } entropy_source_t; | |
265 | ||
266 | double stir_from_system(void); | |
267 | double stir_from_programs(void); | |
268 | double stir_gettimeofday(double entropy_estimate); | |
269 | double stir_clock(double entropy_estimate); | |
270 | double stir_rusage(int who, double entropy_estimate); | |
271 | double hash_output_from_command(entropy_source_t *src, char *hash); | |
272 | ||
273 | /* this is initialised from a file, by prng_read_commands() */ | |
274 | entropy_source_t *entropy_sources = NULL; | |
275 | ||
276 | double | |
277 | stir_from_system(void) | |
278 | { | |
279 | double total_entropy_estimate; | |
280 | long int i; | |
281 | ||
282 | total_entropy_estimate = 0; | |
283 | ||
284 | i = getpid(); | |
285 | RAND_add(&i, sizeof(i), 0.5); | |
286 | total_entropy_estimate += 0.1; | |
287 | ||
288 | i = getppid(); | |
289 | RAND_add(&i, sizeof(i), 0.5); | |
290 | total_entropy_estimate += 0.1; | |
291 | ||
292 | i = getuid(); | |
293 | RAND_add(&i, sizeof(i), 0.0); | |
294 | i = getgid(); | |
295 | RAND_add(&i, sizeof(i), 0.0); | |
296 | ||
297 | total_entropy_estimate += stir_gettimeofday(1.0); | |
298 | total_entropy_estimate += stir_clock(0.5); | |
299 | total_entropy_estimate += stir_rusage(RUSAGE_SELF, 2.0); | |
300 | ||
301 | return(total_entropy_estimate); | |
302 | } | |
303 | ||
304 | double | |
305 | stir_from_programs(void) | |
306 | { | |
307 | int i; | |
308 | int c; | |
309 | double entropy_estimate; | |
310 | double total_entropy_estimate; | |
311 | char hash[SHA_DIGEST_LENGTH]; | |
312 | ||
313 | total_entropy_estimate = 0; | |
314 | for(i = 0; i < NUM_ENTROPY_RUNS; i++) { | |
315 | c = 0; | |
316 | while (entropy_sources[c].path != NULL) { | |
317 | ||
318 | if (!entropy_sources[c].badness) { | |
319 | /* Hash output from command */ | |
320 | entropy_estimate = hash_output_from_command(&entropy_sources[c], hash); | |
321 | ||
322 | /* Scale back entropy estimate according to command's rate */ | |
323 | entropy_estimate *= entropy_sources[c].rate; | |
324 | ||
325 | /* Upper bound of entropy estimate is SHA_DIGEST_LENGTH */ | |
326 | if (entropy_estimate > SHA_DIGEST_LENGTH) | |
327 | entropy_estimate = SHA_DIGEST_LENGTH; | |
328 | ||
329 | /* Scale back estimates for subsequent passes through list */ | |
330 | entropy_estimate /= SCALE_PER_RUN * (i + 1.0); | |
331 | ||
332 | /* Stir it in */ | |
333 | RAND_add(hash, sizeof(hash), entropy_estimate); | |
334 | ||
335 | debug3("Got %0.2f bytes of entropy from '%s'", entropy_estimate, | |
336 | entropy_sources[c].cmdstring); | |
337 | ||
338 | total_entropy_estimate += entropy_estimate; | |
339 | ||
340 | /* Execution times should be a little unpredictable */ | |
341 | total_entropy_estimate += stir_gettimeofday(0.05); | |
342 | total_entropy_estimate += stir_clock(0.05); | |
343 | total_entropy_estimate += stir_rusage(RUSAGE_SELF, 0.1); | |
344 | total_entropy_estimate += stir_rusage(RUSAGE_CHILDREN, 0.1); | |
345 | } else { | |
346 | debug2("Command '%s' disabled (badness %d)", | |
347 | entropy_sources[c].cmdstring, entropy_sources[c].badness); | |
348 | ||
349 | if (entropy_sources[c].badness > 0) | |
350 | entropy_sources[c].badness--; | |
351 | } | |
352 | ||
353 | c++; | |
354 | } | |
355 | } | |
356 | ||
357 | return(total_entropy_estimate); | |
358 | } | |
359 | ||
360 | double | |
361 | stir_gettimeofday(double entropy_estimate) | |
362 | { | |
363 | struct timeval tv; | |
364 | ||
365 | if (gettimeofday(&tv, NULL) == -1) | |
366 | fatal("Couldn't gettimeofday: %s", strerror(errno)); | |
367 | ||
368 | RAND_add(&tv, sizeof(tv), entropy_estimate); | |
369 | ||
370 | return(entropy_estimate); | |
371 | } | |
372 | ||
373 | double | |
374 | stir_clock(double entropy_estimate) | |
375 | { | |
376 | #ifdef HAVE_CLOCK | |
377 | clock_t c; | |
378 | ||
379 | c = clock(); | |
380 | RAND_add(&c, sizeof(c), entropy_estimate); | |
381 | ||
382 | return(entropy_estimate); | |
383 | #else /* _HAVE_CLOCK */ | |
384 | return(0); | |
385 | #endif /* _HAVE_CLOCK */ | |
386 | } | |
387 | ||
388 | double | |
389 | stir_rusage(int who, double entropy_estimate) | |
390 | { | |
391 | #ifdef HAVE_GETRUSAGE | |
392 | struct rusage ru; | |
393 | ||
394 | if (getrusage(who, &ru) == -1) | |
395 | return(0); | |
396 | ||
397 | RAND_add(&ru, sizeof(ru), entropy_estimate); | |
398 | ||
399 | return(entropy_estimate); | |
400 | #else /* _HAVE_GETRUSAGE */ | |
401 | return(0); | |
402 | #endif /* _HAVE_GETRUSAGE */ | |
403 | } | |
404 | ||
405 | ||
406 | static | |
407 | int | |
408 | _get_timeval_msec_difference(struct timeval *t1, struct timeval *t2) { | |
409 | int secdiff, usecdiff; | |
410 | ||
411 | secdiff = t2->tv_sec - t1->tv_sec; | |
412 | usecdiff = (secdiff*1000000) + (t2->tv_usec - t1->tv_usec); | |
413 | return (int)(usecdiff / 1000); | |
414 | } | |
415 | ||
416 | double | |
417 | hash_output_from_command(entropy_source_t *src, char *hash) | |
418 | { | |
419 | static int devnull = -1; | |
420 | int p[2]; | |
421 | fd_set rdset; | |
422 | int cmd_eof = 0, error_abort = 0; | |
423 | struct timeval tv_start, tv_current; | |
424 | int msec_elapsed = 0; | |
425 | pid_t pid; | |
426 | int status; | |
427 | char buf[16384]; | |
428 | int bytes_read; | |
429 | int total_bytes_read; | |
430 | SHA_CTX sha; | |
431 | ||
432 | debug3("Reading output from \'%s\'", src->cmdstring); | |
433 | ||
434 | if (devnull == -1) { | |
435 | devnull = open("/dev/null", O_RDWR); | |
436 | if (devnull == -1) | |
437 | fatal("Couldn't open /dev/null: %s", strerror(errno)); | |
438 | } | |
439 | ||
440 | if (pipe(p) == -1) | |
441 | fatal("Couldn't open pipe: %s", strerror(errno)); | |
442 | ||
443 | (void)gettimeofday(&tv_start, NULL); /* record start time */ | |
444 | ||
445 | switch (pid = fork()) { | |
446 | case -1: /* Error */ | |
447 | close(p[0]); | |
448 | close(p[1]); | |
449 | fatal("Couldn't fork: %s", strerror(errno)); | |
450 | /* NOTREACHED */ | |
451 | case 0: /* Child */ | |
452 | dup2(devnull, STDIN_FILENO); | |
453 | dup2(p[1], STDOUT_FILENO); | |
454 | dup2(p[1], STDERR_FILENO); | |
455 | close(p[0]); | |
456 | close(p[1]); | |
457 | close(devnull); | |
458 | ||
459 | setuid(original_uid); | |
460 | execv(src->path, (char**)(src->args)); | |
461 | debug("(child) Couldn't exec '%s': %s", src->cmdstring, | |
462 | strerror(errno)); | |
463 | _exit(-1); | |
464 | default: /* Parent */ | |
465 | break; | |
466 | } | |
467 | ||
468 | RAND_add(&pid, sizeof(&pid), 0.0); | |
469 | ||
470 | close(p[1]); | |
471 | ||
472 | /* Hash output from child */ | |
473 | SHA1_Init(&sha); | |
474 | total_bytes_read = 0; | |
475 | ||
476 | while (!error_abort && !cmd_eof) { | |
477 | int ret; | |
478 | struct timeval tv; | |
479 | int msec_remaining; | |
480 | ||
481 | (void) gettimeofday(&tv_current, 0); | |
482 | msec_elapsed = _get_timeval_msec_difference(&tv_start, &tv_current); | |
483 | if (msec_elapsed >= entropy_timeout_current) { | |
484 | error_abort=1; | |
485 | continue; | |
486 | } | |
487 | msec_remaining = entropy_timeout_current - msec_elapsed; | |
488 | ||
489 | FD_ZERO(&rdset); | |
490 | FD_SET(p[0], &rdset); | |
491 | tv.tv_sec = msec_remaining / 1000; | |
492 | tv.tv_usec = (msec_remaining % 1000) * 1000; | |
493 | ||
494 | ret = select(p[0]+1, &rdset, NULL, NULL, &tv); | |
495 | ||
496 | RAND_add(&tv, sizeof(tv), 0.0); | |
497 | ||
498 | switch (ret) { | |
499 | case 0: | |
500 | /* timer expired */ | |
501 | error_abort = 1; | |
502 | break; | |
503 | case 1: | |
504 | /* command input */ | |
505 | bytes_read = read(p[0], buf, sizeof(buf)); | |
506 | RAND_add(&bytes_read, sizeof(&bytes_read), 0.0); | |
507 | if (bytes_read == -1) { | |
508 | error_abort = 1; | |
509 | break; | |
510 | } else if (bytes_read) { | |
511 | SHA1_Update(&sha, buf, bytes_read); | |
512 | total_bytes_read += bytes_read; | |
513 | } else { | |
514 | cmd_eof = 1; | |
515 | } | |
516 | break; | |
517 | case -1: | |
518 | default: | |
519 | /* error */ | |
520 | debug("Command '%s': select() failed: %s", src->cmdstring, | |
521 | strerror(errno)); | |
522 | error_abort = 1; | |
523 | break; | |
524 | } | |
525 | } | |
526 | ||
527 | SHA1_Final(hash, &sha); | |
528 | ||
529 | close(p[0]); | |
530 | ||
531 | debug3("Time elapsed: %d msec", msec_elapsed); | |
532 | ||
533 | if (waitpid(pid, &status, 0) == -1) { | |
534 | error("Couldn't wait for child '%s' completion: %s", src->cmdstring, | |
535 | strerror(errno)); | |
536 | return(0.0); | |
537 | } | |
538 | ||
539 | RAND_add(&status, sizeof(&status), 0.0); | |
540 | ||
541 | if (error_abort) { | |
542 | /* closing p[0] on timeout causes the entropy command to | |
543 | * SIGPIPE. Take whatever output we got, and mark this command | |
544 | * as slow */ | |
545 | debug2("Command '%s' timed out", src->cmdstring); | |
546 | src->sticky_badness *= 2; | |
547 | src->badness = src->sticky_badness; | |
548 | return(total_bytes_read); | |
549 | } | |
550 | ||
551 | if (WIFEXITED(status)) { | |
552 | if (WEXITSTATUS(status)==0) { | |
553 | return(total_bytes_read); | |
554 | } else { | |
555 | debug2("Command '%s' exit status was %d", src->cmdstring, | |
556 | WEXITSTATUS(status)); | |
557 | src->badness = src->sticky_badness = 128; | |
558 | return (0.0); | |
559 | } | |
560 | } else if (WIFSIGNALED(status)) { | |
561 | debug2("Command '%s' returned on uncaught signal %d !", src->cmdstring, | |
562 | status); | |
563 | src->badness = src->sticky_badness = 128; | |
564 | return(0.0); | |
565 | } else | |
566 | return(0.0); | |
567 | } | |
568 | ||
569 | /* | |
570 | * prng seedfile functions | |
571 | */ | |
572 | int | |
573 | prng_check_seedfile(char *filename) { | |
574 | ||
575 | struct stat st; | |
576 | ||
577 | /* FIXME raceable: eg replace seed between this stat and subsequent open */ | |
578 | /* Not such a problem because we don't trust the seed file anyway */ | |
579 | if (lstat(filename, &st) == -1) { | |
580 | /* Give up on hard errors */ | |
581 | if (errno != ENOENT) | |
582 | debug("WARNING: Couldn't stat random seed file \"%s\": %s", | |
583 | filename, strerror(errno)); | |
584 | ||
585 | return(0); | |
586 | } | |
587 | ||
588 | /* regular file? */ | |
589 | if (!S_ISREG(st.st_mode)) | |
590 | fatal("PRNG seedfile %.100s is not a regular file", filename); | |
591 | ||
592 | /* mode 0600, owned by root or the current user? */ | |
593 | if (((st.st_mode & 0177) != 0) || !(st.st_uid == original_uid)) { | |
594 | debug("WARNING: PRNG seedfile %.100s must be mode 0600, owned by uid %d", | |
595 | filename, getuid()); | |
596 | return(0); | |
597 | } | |
598 | ||
599 | return(1); | |
600 | } | |
601 | ||
602 | void | |
603 | prng_write_seedfile(void) { | |
604 | int fd; | |
605 | char seed[1024]; | |
606 | char filename[1024]; | |
607 | struct passwd *pw; | |
608 | ||
609 | /* Don't bother if we have already saved a seed */ | |
610 | if (prng_seed_saved) | |
611 | return; | |
612 | ||
613 | setuid(original_uid); | |
614 | ||
615 | prng_seed_saved = 1; | |
616 | ||
617 | pw = getpwuid(original_uid); | |
618 | if (pw == NULL) | |
619 | fatal("Couldn't get password entry for current user (%i): %s", | |
620 | original_uid, strerror(errno)); | |
621 | ||
622 | /* Try to ensure that the parent directory is there */ | |
623 | snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir, | |
624 | _PATH_SSH_USER_DIR); | |
625 | mkdir(filename, 0700); | |
626 | ||
627 | snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir, | |
628 | SSH_PRNG_SEED_FILE); | |
629 | ||
630 | debug("writing PRNG seed to file %.100s", filename); | |
631 | ||
632 | RAND_bytes(seed, sizeof(seed)); | |
633 | ||
634 | /* Don't care if the seed doesn't exist */ | |
635 | prng_check_seedfile(filename); | |
636 | ||
637 | if ((fd = open(filename, O_WRONLY|O_TRUNC|O_CREAT, 0600)) == -1) { | |
638 | debug("WARNING: couldn't access PRNG seedfile %.100s (%.100s)", | |
639 | filename, strerror(errno)); | |
640 | } else { | |
641 | if (atomicio(write, fd, &seed, sizeof(seed)) != sizeof(seed)) | |
642 | fatal("problem writing PRNG seedfile %.100s (%.100s)", filename, | |
643 | strerror(errno)); | |
644 | ||
645 | close(fd); | |
646 | } | |
647 | } | |
648 | ||
649 | void | |
650 | prng_read_seedfile(void) { | |
651 | int fd; | |
652 | char seed[1024]; | |
653 | char filename[1024]; | |
654 | struct passwd *pw; | |
655 | ||
656 | pw = getpwuid(original_uid); | |
657 | if (pw == NULL) | |
658 | fatal("Couldn't get password entry for current user (%i): %s", | |
659 | original_uid, strerror(errno)); | |
660 | ||
661 | snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir, | |
662 | SSH_PRNG_SEED_FILE); | |
663 | ||
664 | debug("loading PRNG seed from file %.100s", filename); | |
665 | ||
666 | if (!prng_check_seedfile(filename)) { | |
667 | verbose("Random seed file not found or not valid, ignoring."); | |
668 | return; | |
669 | } | |
670 | ||
671 | /* open the file and read in the seed */ | |
672 | fd = open(filename, O_RDONLY); | |
673 | if (fd == -1) | |
674 | fatal("could not open PRNG seedfile %.100s (%.100s)", filename, | |
675 | strerror(errno)); | |
676 | ||
677 | if (atomicio(read, fd, &seed, sizeof(seed)) != sizeof(seed)) { | |
678 | verbose("invalid or short read from PRNG seedfile %.100s - ignoring", | |
679 | filename); | |
680 | memset(seed, '\0', sizeof(seed)); | |
681 | } | |
682 | close(fd); | |
683 | ||
684 | /* stir in the seed, with estimated entropy zero */ | |
685 | RAND_add(&seed, sizeof(seed), 0.0); | |
686 | } | |
687 | ||
688 | ||
689 | /* | |
690 | * entropy command initialisation functions | |
691 | */ | |
692 | int | |
693 | prng_read_commands(char *cmdfilename) | |
694 | { | |
695 | FILE *f; | |
696 | char *cp; | |
697 | char line[1024]; | |
698 | char cmd[1024]; | |
699 | char path[256]; | |
700 | int linenum; | |
701 | int num_cmds = 64; | |
702 | int cur_cmd = 0; | |
703 | double est; | |
704 | entropy_source_t *entcmd; | |
705 | ||
706 | f = fopen(cmdfilename, "r"); | |
707 | if (!f) { | |
708 | fatal("couldn't read entropy commands file %.100s: %.100s", | |
709 | cmdfilename, strerror(errno)); | |
710 | } | |
711 | ||
712 | entcmd = (entropy_source_t *)xmalloc(num_cmds * sizeof(entropy_source_t)); | |
713 | memset(entcmd, '\0', num_cmds * sizeof(entropy_source_t)); | |
714 | ||
715 | /* Read in file */ | |
716 | linenum = 0; | |
717 | while (fgets(line, sizeof(line), f)) { | |
718 | int arg; | |
719 | char *argv; | |
720 | ||
721 | linenum++; | |
722 | ||
723 | /* skip leading whitespace, test for blank line or comment */ | |
724 | cp = line + strspn(line, WHITESPACE); | |
725 | if ((*cp == 0) || (*cp == '#')) | |
726 | continue; /* done with this line */ | |
727 | ||
728 | /* First non-whitespace char should be double quote delimiting */ | |
729 | /* commandline */ | |
730 | if (*cp != '"') { | |
731 | error("bad entropy command, %.100s line %d", cmdfilename, | |
732 | linenum); | |
733 | continue; | |
734 | } | |
735 | ||
736 | /* first token, command args (incl. argv[0]) in double quotes */ | |
737 | cp = strtok(cp, "\""); | |
738 | if (cp == NULL) { | |
739 | error("missing or bad command string, %.100s line %d -- ignored", | |
740 | cmdfilename, linenum); | |
741 | continue; | |
742 | } | |
743 | strlcpy(cmd, cp, sizeof(cmd)); | |
744 | ||
745 | /* second token, full command path */ | |
746 | if ((cp = strtok(NULL, WHITESPACE)) == NULL) { | |
747 | error("missing command path, %.100s line %d -- ignored", | |
748 | cmdfilename, linenum); | |
749 | continue; | |
750 | } | |
751 | ||
752 | /* did configure mark this as dead? */ | |
753 | if (strncmp("undef", cp, 5) == 0) | |
754 | continue; | |
755 | ||
756 | strlcpy(path, cp, sizeof(path)); | |
757 | ||
758 | /* third token, entropy rate estimate for this command */ | |
759 | if ((cp = strtok(NULL, WHITESPACE)) == NULL) { | |
760 | error("missing entropy estimate, %.100s line %d -- ignored", | |
761 | cmdfilename, linenum); | |
762 | continue; | |
763 | } | |
764 | est = strtod(cp, &argv); | |
765 | ||
766 | /* end of line */ | |
767 | if ((cp = strtok(NULL, WHITESPACE)) != NULL) { | |
768 | error("garbage at end of line %d in %.100s -- ignored", linenum, | |
769 | cmdfilename); | |
770 | continue; | |
771 | } | |
772 | ||
773 | /* save the command for debug messages */ | |
774 | entcmd[cur_cmd].cmdstring = xstrdup(cmd); | |
775 | ||
776 | /* split the command args */ | |
777 | cp = strtok(cmd, WHITESPACE); | |
778 | arg = 0; | |
779 | argv = NULL; | |
780 | do { | |
781 | char *s = (char*)xmalloc(strlen(cp) + 1); | |
782 | strncpy(s, cp, strlen(cp) + 1); | |
783 | entcmd[cur_cmd].args[arg] = s; | |
784 | arg++; | |
785 | } while ((arg < 5) && (cp = strtok(NULL, WHITESPACE))); | |
786 | ||
787 | if (strtok(NULL, WHITESPACE)) | |
788 | error("ignored extra command elements (max 5), %.100s line %d", | |
789 | cmdfilename, linenum); | |
790 | ||
791 | /* Copy the command path and rate estimate */ | |
792 | entcmd[cur_cmd].path = xstrdup(path); | |
793 | entcmd[cur_cmd].rate = est; | |
794 | ||
795 | /* Initialise other values */ | |
796 | entcmd[cur_cmd].sticky_badness = 1; | |
797 | ||
798 | cur_cmd++; | |
799 | ||
800 | /* If we've filled the array, reallocate it twice the size */ | |
801 | /* Do this now because even if this we're on the last command, | |
802 | we need another slot to mark the last entry */ | |
803 | if (cur_cmd == num_cmds) { | |
804 | num_cmds *= 2; | |
805 | entcmd = xrealloc(entcmd, num_cmds * sizeof(entropy_source_t)); | |
806 | } | |
807 | } | |
808 | ||
809 | /* zero the last entry */ | |
810 | memset(&entcmd[cur_cmd], '\0', sizeof(entropy_source_t)); | |
811 | ||
812 | /* trim to size */ | |
813 | entropy_sources = xrealloc(entcmd, (cur_cmd+1) * sizeof(entropy_source_t)); | |
814 | ||
815 | debug("Loaded %d entropy commands from %.100s", cur_cmd, cmdfilename); | |
816 | ||
817 | return (cur_cmd >= MIN_ENTROPY_SOURCES); | |
818 | } | |
819 | ||
820 | /* | |
821 | * Write a keyfile at exit | |
822 | */ | |
823 | void | |
824 | prng_seed_cleanup(void *junk) | |
825 | { | |
826 | prng_write_seedfile(); | |
827 | } | |
828 | ||
829 | /* | |
830 | * Conditionally Seed OpenSSL's random number pool from | |
831 | * syscalls and program output | |
832 | */ | |
833 | void | |
834 | seed_rng(void) | |
835 | { | |
836 | mysig_t old_sigchld_handler; | |
837 | ||
838 | if (!prng_initialised) | |
839 | fatal("RNG not initialised"); | |
840 | ||
841 | /* Make sure some other sigchld handler doesn't reap our entropy */ | |
842 | /* commands */ | |
843 | old_sigchld_handler = mysignal(SIGCHLD, SIG_DFL); | |
844 | ||
845 | debug("Seeded RNG with %i bytes from programs", (int)stir_from_programs()); | |
846 | debug("Seeded RNG with %i bytes from system calls", (int)stir_from_system()); | |
847 | ||
848 | if (!RAND_status()) | |
849 | fatal("Not enough entropy in RNG"); | |
850 | ||
851 | mysignal(SIGCHLD, old_sigchld_handler); | |
852 | ||
853 | if (!RAND_status()) | |
854 | fatal("Couldn't initialise builtin random number generator -- exiting."); | |
855 | } | |
856 | ||
857 | void init_rng(void) | |
858 | { | |
859 | int original_euid; | |
860 | ||
861 | check_openssl_version(); | |
862 | ||
863 | original_uid = getuid(); | |
864 | original_euid = geteuid(); | |
865 | ||
866 | /* Read in collection commands */ | |
867 | if (!prng_read_commands(SSH_PRNG_COMMAND_FILE)) | |
868 | fatal("PRNG initialisation failed -- exiting."); | |
869 | ||
870 | /* Set ourselves up to save a seed upon exit */ | |
871 | prng_seed_saved = 0; | |
872 | ||
873 | /* Give up privs while reading seed file */ | |
874 | #ifdef SAVED_IDS_WORK_WITH_SETEUID | |
875 | if ((original_uid != original_euid) && (seteuid(original_uid) == -1)) | |
876 | fatal("Couldn't give up privileges"); | |
877 | #else /* SAVED_IDS_WORK_WITH_SETEUID */ | |
878 | /* | |
879 | * Propagate the privileged uid to all of our uids. | |
880 | * Set the effective uid to the given (unprivileged) uid. | |
881 | */ | |
882 | if (original_uid != original_euid && (setuid(original_euid) == -1 || | |
883 | seteuid(original_uid) == -1)) | |
884 | fatal("Couldn't give up privileges"); | |
885 | #endif /* SAVED_IDS_WORK_WITH_SETEUID */ | |
886 | ||
887 | prng_read_seedfile(); | |
888 | ||
889 | #ifdef SAVED_IDS_WORK_WITH_SETEUID | |
890 | if ((original_uid != original_euid) && (seteuid(original_euid) == -1)) | |
891 | fatal("Couldn't restore privileges"); | |
892 | #else /* SAVED_IDS_WORK_WITH_SETEUID */ | |
893 | /* | |
894 | * We are unable to restore the real uid to its unprivileged value. | |
895 | * Propagate the real uid (usually more privileged) to effective uid | |
896 | * as well. | |
897 | */ | |
898 | if (original_uid != original_euid && (seteuid(original_euid) == -1 || | |
899 | setuid(original_uid) == -1)) | |
900 | fatal("Couldn't restore privileges"); | |
901 | #endif /* SAVED_IDS_WORK_WITH_SETEUID */ | |
902 | ||
903 | fatal_add_cleanup(prng_seed_cleanup, NULL); | |
904 | atexit(prng_write_seedfile); | |
905 | ||
906 | prng_initialised = 1; | |
907 | } | |
908 | ||
909 | #endif /* defined(USE_PRNGD) || defined(RANDOM_POOL) */ |