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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 | static void | |
72 | check_openssl_version(void) | |
73 | { | |
74 | if (SSLeay() != OPENSSL_VERSION_NUMBER) | |
75 | fatal("OpenSSL version mismatch. Built against %lx, you " | |
76 | "have %lx", OPENSSL_VERSION_NUMBER, SSLeay()); | |
77 | } | |
78 | ||
79 | #if defined(PRNGD_SOCKET) || defined(PRNGD_PORT) | |
80 | # define USE_PRNGD | |
81 | #endif | |
82 | ||
83 | #if defined(USE_PRNGD) || defined(RANDOM_POOL) | |
84 | ||
85 | #ifdef USE_PRNGD | |
86 | /* Collect entropy from PRNGD/EGD */ | |
87 | int | |
88 | get_random_bytes(unsigned char *buf, int len) | |
89 | { | |
90 | int fd; | |
91 | char msg[2]; | |
92 | #ifdef PRNGD_PORT | |
93 | struct sockaddr_in addr; | |
94 | #else | |
95 | struct sockaddr_un addr; | |
96 | #endif | |
97 | int addr_len, rval, errors; | |
98 | mysig_t old_sigpipe; | |
99 | ||
100 | memset(&addr, '\0', sizeof(addr)); | |
101 | ||
102 | #ifdef PRNGD_PORT | |
103 | addr.sin_family = AF_INET; | |
104 | addr.sin_addr.s_addr = htonl(INADDR_LOOPBACK); | |
105 | addr.sin_port = htons(PRNGD_PORT); | |
106 | addr_len = sizeof(struct sockaddr_in); | |
107 | #else /* use IP socket PRNGD_SOCKET instead */ | |
108 | /* Sanity checks */ | |
109 | if (sizeof(PRNGD_SOCKET) > sizeof(addr.sun_path)) | |
110 | fatal("Random pool path is too long"); | |
111 | if (len > 255) | |
112 | fatal("Too many bytes to read from PRNGD"); | |
113 | ||
114 | addr.sun_family = AF_UNIX; | |
115 | strlcpy(addr.sun_path, PRNGD_SOCKET, sizeof(addr.sun_path)); | |
116 | addr_len = offsetof(struct sockaddr_un, sun_path) + | |
117 | sizeof(PRNGD_SOCKET); | |
118 | #endif | |
119 | ||
120 | old_sigpipe = mysignal(SIGPIPE, SIG_IGN); | |
121 | ||
122 | errors = rval = 0; | |
123 | reopen: | |
124 | #ifdef PRNGD_PORT | |
125 | fd = socket(addr.sin_family, SOCK_STREAM, 0); | |
126 | if (fd == -1) { | |
127 | error("Couldn't create AF_INET socket: %s", strerror(errno)); | |
128 | goto done; | |
129 | } | |
130 | #else | |
131 | fd = socket(addr.sun_family, SOCK_STREAM, 0); | |
132 | if (fd == -1) { | |
133 | error("Couldn't create AF_UNIX socket: %s", strerror(errno)); | |
134 | goto done; | |
135 | } | |
136 | #endif | |
137 | ||
138 | if (connect(fd, (struct sockaddr*)&addr, addr_len) == -1) { | |
139 | #ifdef PRNGD_PORT | |
140 | error("Couldn't connect to PRNGD port %d: %s", | |
141 | PRNGD_PORT, strerror(errno)); | |
142 | #else | |
143 | error("Couldn't connect to PRNGD socket \"%s\": %s", | |
144 | addr.sun_path, strerror(errno)); | |
145 | #endif | |
146 | goto done; | |
147 | } | |
148 | ||
149 | /* Send blocking read request to PRNGD */ | |
150 | msg[0] = 0x02; | |
151 | msg[1] = len; | |
152 | ||
153 | if (atomicio(write, fd, msg, sizeof(msg)) != sizeof(msg)) { | |
154 | if (errno == EPIPE && errors < 10) { | |
155 | close(fd); | |
156 | errors++; | |
157 | goto reopen; | |
158 | } | |
159 | error("Couldn't write to PRNGD socket: %s", | |
160 | strerror(errno)); | |
161 | goto done; | |
162 | } | |
163 | ||
164 | if (atomicio(read, fd, buf, len) != len) { | |
165 | if (errno == EPIPE && errors < 10) { | |
166 | close(fd); | |
167 | errors++; | |
168 | goto reopen; | |
169 | } | |
170 | error("Couldn't read from PRNGD socket: %s", | |
171 | strerror(errno)); | |
172 | goto done; | |
173 | } | |
174 | ||
175 | rval = 1; | |
176 | done: | |
177 | mysignal(SIGPIPE, old_sigpipe); | |
178 | if (fd != -1) | |
179 | close(fd); | |
180 | return(rval); | |
181 | } | |
182 | #else /* !USE_PRNGD */ | |
183 | #ifdef RANDOM_POOL | |
184 | /* Collect entropy from /dev/urandom or pipe */ | |
185 | static int | |
186 | get_random_bytes(unsigned char *buf, int len) | |
187 | { | |
188 | int random_pool; | |
189 | ||
190 | random_pool = open(RANDOM_POOL, O_RDONLY); | |
191 | if (random_pool == -1) { | |
192 | error("Couldn't open random pool \"%s\": %s", | |
193 | RANDOM_POOL, strerror(errno)); | |
194 | return(0); | |
195 | } | |
196 | ||
197 | if (atomicio(read, random_pool, buf, len) != len) { | |
198 | error("Couldn't read from random pool \"%s\": %s", | |
199 | RANDOM_POOL, strerror(errno)); | |
200 | close(random_pool); | |
201 | return(0); | |
202 | } | |
203 | ||
204 | close(random_pool); | |
205 | ||
206 | return(1); | |
207 | } | |
208 | #endif /* RANDOM_POOL */ | |
209 | #endif /* USE_PRNGD */ | |
210 | ||
211 | /* | |
212 | * Seed OpenSSL's random number pool from Kernel random number generator | |
213 | * or PRNGD/EGD | |
214 | */ | |
215 | void | |
216 | seed_rng(void) | |
217 | { | |
218 | unsigned char buf[32]; | |
219 | ||
220 | debug("Seeding random number generator"); | |
221 | ||
222 | if (!get_random_bytes(buf, sizeof(buf))) { | |
223 | if (!RAND_status()) | |
224 | fatal("Entropy collection failed and entropy exhausted"); | |
225 | } else { | |
226 | RAND_add(buf, sizeof(buf), sizeof(buf)); | |
227 | } | |
228 | ||
229 | memset(buf, '\0', sizeof(buf)); | |
230 | } | |
231 | ||
232 | void | |
233 | init_rng(void) | |
234 | { | |
235 | check_openssl_version(); | |
236 | } | |
237 | ||
238 | #else /* defined(USE_PRNGD) || defined(RANDOM_POOL) */ | |
239 | ||
240 | /* | |
241 | * FIXME: proper entropy estimations. All current values are guesses | |
242 | * FIXME: (ATL) do estimates at compile time? | |
243 | * FIXME: More entropy sources | |
244 | */ | |
245 | ||
246 | /* slow command timeouts (all in milliseconds) */ | |
247 | /* static int entropy_timeout_default = ENTROPY_TIMEOUT_MSEC; */ | |
248 | static int entropy_timeout_current = ENTROPY_TIMEOUT_MSEC; | |
249 | ||
250 | static int prng_seed_saved = 0; | |
251 | static int prng_initialised = 0; | |
252 | uid_t original_uid; | |
253 | ||
254 | typedef struct | |
255 | { | |
256 | /* Proportion of data that is entropy */ | |
257 | double rate; | |
258 | /* Counter goes positive if this command times out */ | |
259 | unsigned int badness; | |
260 | /* Increases by factor of two each timeout */ | |
261 | unsigned int sticky_badness; | |
262 | /* Path to executable */ | |
263 | char *path; | |
264 | /* argv to pass to executable */ | |
265 | char *args[5]; | |
266 | /* full command string (debug) */ | |
267 | char *cmdstring; | |
268 | } entropy_source_t; | |
269 | ||
270 | double stir_from_system(void); | |
271 | double stir_from_programs(void); | |
272 | double stir_gettimeofday(double entropy_estimate); | |
273 | double stir_clock(double entropy_estimate); | |
274 | double stir_rusage(int who, double entropy_estimate); | |
275 | double hash_output_from_command(entropy_source_t *src, char *hash); | |
276 | ||
277 | /* this is initialised from a file, by prng_read_commands() */ | |
278 | entropy_source_t *entropy_sources = NULL; | |
279 | ||
280 | double | |
281 | stir_from_system(void) | |
282 | { | |
283 | double total_entropy_estimate; | |
284 | long int i; | |
285 | ||
286 | total_entropy_estimate = 0; | |
287 | ||
288 | i = getpid(); | |
289 | RAND_add(&i, sizeof(i), 0.5); | |
290 | total_entropy_estimate += 0.1; | |
291 | ||
292 | i = getppid(); | |
293 | RAND_add(&i, sizeof(i), 0.5); | |
294 | total_entropy_estimate += 0.1; | |
295 | ||
296 | i = getuid(); | |
297 | RAND_add(&i, sizeof(i), 0.0); | |
298 | i = getgid(); | |
299 | RAND_add(&i, sizeof(i), 0.0); | |
300 | ||
301 | total_entropy_estimate += stir_gettimeofday(1.0); | |
302 | total_entropy_estimate += stir_clock(0.5); | |
303 | total_entropy_estimate += stir_rusage(RUSAGE_SELF, 2.0); | |
304 | ||
305 | return(total_entropy_estimate); | |
306 | } | |
307 | ||
308 | double | |
309 | stir_from_programs(void) | |
310 | { | |
311 | int i; | |
312 | int c; | |
313 | double entropy_estimate; | |
314 | double total_entropy_estimate; | |
315 | char hash[SHA_DIGEST_LENGTH]; | |
316 | ||
317 | total_entropy_estimate = 0; | |
318 | for(i = 0; i < NUM_ENTROPY_RUNS; i++) { | |
319 | c = 0; | |
320 | while (entropy_sources[c].path != NULL) { | |
321 | ||
322 | if (!entropy_sources[c].badness) { | |
323 | /* Hash output from command */ | |
324 | entropy_estimate = hash_output_from_command(&entropy_sources[c], hash); | |
325 | ||
326 | /* Scale back entropy estimate according to command's rate */ | |
327 | entropy_estimate *= entropy_sources[c].rate; | |
328 | ||
329 | /* Upper bound of entropy estimate is SHA_DIGEST_LENGTH */ | |
330 | if (entropy_estimate > SHA_DIGEST_LENGTH) | |
331 | entropy_estimate = SHA_DIGEST_LENGTH; | |
332 | ||
333 | /* Scale back estimates for subsequent passes through list */ | |
334 | entropy_estimate /= SCALE_PER_RUN * (i + 1.0); | |
335 | ||
336 | /* Stir it in */ | |
337 | RAND_add(hash, sizeof(hash), entropy_estimate); | |
338 | ||
339 | debug3("Got %0.2f bytes of entropy from '%s'", entropy_estimate, | |
340 | entropy_sources[c].cmdstring); | |
341 | ||
342 | total_entropy_estimate += entropy_estimate; | |
343 | ||
344 | /* Execution times should be a little unpredictable */ | |
345 | total_entropy_estimate += stir_gettimeofday(0.05); | |
346 | total_entropy_estimate += stir_clock(0.05); | |
347 | total_entropy_estimate += stir_rusage(RUSAGE_SELF, 0.1); | |
348 | total_entropy_estimate += stir_rusage(RUSAGE_CHILDREN, 0.1); | |
349 | } else { | |
350 | debug2("Command '%s' disabled (badness %d)", | |
351 | entropy_sources[c].cmdstring, entropy_sources[c].badness); | |
352 | ||
353 | if (entropy_sources[c].badness > 0) | |
354 | entropy_sources[c].badness--; | |
355 | } | |
356 | ||
357 | c++; | |
358 | } | |
359 | } | |
360 | ||
361 | return(total_entropy_estimate); | |
362 | } | |
363 | ||
364 | double | |
365 | stir_gettimeofday(double entropy_estimate) | |
366 | { | |
367 | struct timeval tv; | |
368 | ||
369 | if (gettimeofday(&tv, NULL) == -1) | |
370 | fatal("Couldn't gettimeofday: %s", strerror(errno)); | |
371 | ||
372 | RAND_add(&tv, sizeof(tv), entropy_estimate); | |
373 | ||
374 | return(entropy_estimate); | |
375 | } | |
376 | ||
377 | double | |
378 | stir_clock(double entropy_estimate) | |
379 | { | |
380 | #ifdef HAVE_CLOCK | |
381 | clock_t c; | |
382 | ||
383 | c = clock(); | |
384 | RAND_add(&c, sizeof(c), entropy_estimate); | |
385 | ||
386 | return(entropy_estimate); | |
387 | #else /* _HAVE_CLOCK */ | |
388 | return(0); | |
389 | #endif /* _HAVE_CLOCK */ | |
390 | } | |
391 | ||
392 | double | |
393 | stir_rusage(int who, double entropy_estimate) | |
394 | { | |
395 | #ifdef HAVE_GETRUSAGE | |
396 | struct rusage ru; | |
397 | ||
398 | if (getrusage(who, &ru) == -1) | |
399 | return(0); | |
400 | ||
401 | RAND_add(&ru, sizeof(ru), entropy_estimate); | |
402 | ||
403 | return(entropy_estimate); | |
404 | #else /* _HAVE_GETRUSAGE */ | |
405 | return(0); | |
406 | #endif /* _HAVE_GETRUSAGE */ | |
407 | } | |
408 | ||
409 | ||
410 | static int | |
411 | _get_timeval_msec_difference(struct timeval *t1, struct timeval *t2) { | |
412 | int secdiff, usecdiff; | |
413 | ||
414 | secdiff = t2->tv_sec - t1->tv_sec; | |
415 | usecdiff = (secdiff*1000000) + (t2->tv_usec - t1->tv_usec); | |
416 | return (int)(usecdiff / 1000); | |
417 | } | |
418 | ||
419 | double | |
420 | hash_output_from_command(entropy_source_t *src, char *hash) | |
421 | { | |
422 | static int devnull = -1; | |
423 | int p[2]; | |
424 | fd_set rdset; | |
425 | int cmd_eof = 0, error_abort = 0; | |
426 | struct timeval tv_start, tv_current; | |
427 | int msec_elapsed = 0; | |
428 | pid_t pid; | |
429 | int status; | |
430 | char buf[16384]; | |
431 | int bytes_read; | |
432 | int total_bytes_read; | |
433 | SHA_CTX sha; | |
434 | ||
435 | debug3("Reading output from \'%s\'", src->cmdstring); | |
436 | ||
437 | if (devnull == -1) { | |
438 | devnull = open("/dev/null", O_RDWR); | |
439 | if (devnull == -1) | |
440 | fatal("Couldn't open /dev/null: %s", strerror(errno)); | |
441 | } | |
442 | ||
443 | if (pipe(p) == -1) | |
444 | fatal("Couldn't open pipe: %s", strerror(errno)); | |
445 | ||
446 | (void)gettimeofday(&tv_start, NULL); /* record start time */ | |
447 | ||
448 | switch (pid = fork()) { | |
449 | case -1: /* Error */ | |
450 | close(p[0]); | |
451 | close(p[1]); | |
452 | fatal("Couldn't fork: %s", strerror(errno)); | |
453 | /* NOTREACHED */ | |
454 | case 0: /* Child */ | |
455 | dup2(devnull, STDIN_FILENO); | |
456 | dup2(p[1], STDOUT_FILENO); | |
457 | dup2(p[1], STDERR_FILENO); | |
458 | close(p[0]); | |
459 | close(p[1]); | |
460 | close(devnull); | |
461 | ||
462 | setuid(original_uid); | |
463 | execv(src->path, (char**)(src->args)); | |
464 | debug("(child) Couldn't exec '%s': %s", src->cmdstring, | |
465 | strerror(errno)); | |
466 | _exit(-1); | |
467 | default: /* Parent */ | |
468 | break; | |
469 | } | |
470 | ||
471 | RAND_add(&pid, sizeof(&pid), 0.0); | |
472 | ||
473 | close(p[1]); | |
474 | ||
475 | /* Hash output from child */ | |
476 | SHA1_Init(&sha); | |
477 | total_bytes_read = 0; | |
478 | ||
479 | while (!error_abort && !cmd_eof) { | |
480 | int ret; | |
481 | struct timeval tv; | |
482 | int msec_remaining; | |
483 | ||
484 | (void) gettimeofday(&tv_current, 0); | |
485 | msec_elapsed = _get_timeval_msec_difference(&tv_start, &tv_current); | |
486 | if (msec_elapsed >= entropy_timeout_current) { | |
487 | error_abort=1; | |
488 | continue; | |
489 | } | |
490 | msec_remaining = entropy_timeout_current - msec_elapsed; | |
491 | ||
492 | FD_ZERO(&rdset); | |
493 | FD_SET(p[0], &rdset); | |
494 | tv.tv_sec = msec_remaining / 1000; | |
495 | tv.tv_usec = (msec_remaining % 1000) * 1000; | |
496 | ||
497 | ret = select(p[0]+1, &rdset, NULL, NULL, &tv); | |
498 | ||
499 | RAND_add(&tv, sizeof(tv), 0.0); | |
500 | ||
501 | switch (ret) { | |
502 | case 0: | |
503 | /* timer expired */ | |
504 | error_abort = 1; | |
505 | break; | |
506 | case 1: | |
507 | /* command input */ | |
508 | do { | |
509 | bytes_read = read(p[0], buf, sizeof(buf)); | |
510 | } while (bytes_read == -1 && errno == EINTR); | |
511 | RAND_add(&bytes_read, sizeof(&bytes_read), 0.0); | |
512 | if (bytes_read == -1) { | |
513 | error_abort = 1; | |
514 | break; | |
515 | } else if (bytes_read) { | |
516 | SHA1_Update(&sha, buf, bytes_read); | |
517 | total_bytes_read += bytes_read; | |
518 | } else { | |
519 | cmd_eof = 1; | |
520 | } | |
521 | break; | |
522 | case -1: | |
523 | default: | |
524 | /* error */ | |
525 | debug("Command '%s': select() failed: %s", src->cmdstring, | |
526 | strerror(errno)); | |
527 | error_abort = 1; | |
528 | break; | |
529 | } | |
530 | } | |
531 | ||
532 | SHA1_Final(hash, &sha); | |
533 | ||
534 | close(p[0]); | |
535 | ||
536 | debug3("Time elapsed: %d msec", msec_elapsed); | |
537 | ||
538 | if (waitpid(pid, &status, 0) == -1) { | |
539 | error("Couldn't wait for child '%s' completion: %s", src->cmdstring, | |
540 | strerror(errno)); | |
541 | return(0.0); | |
542 | } | |
543 | ||
544 | RAND_add(&status, sizeof(&status), 0.0); | |
545 | ||
546 | if (error_abort) { | |
547 | /* closing p[0] on timeout causes the entropy command to | |
548 | * SIGPIPE. Take whatever output we got, and mark this command | |
549 | * as slow */ | |
550 | debug2("Command '%s' timed out", src->cmdstring); | |
551 | src->sticky_badness *= 2; | |
552 | src->badness = src->sticky_badness; | |
553 | return(total_bytes_read); | |
554 | } | |
555 | ||
556 | if (WIFEXITED(status)) { | |
557 | if (WEXITSTATUS(status)==0) { | |
558 | return(total_bytes_read); | |
559 | } else { | |
560 | debug2("Command '%s' exit status was %d", src->cmdstring, | |
561 | WEXITSTATUS(status)); | |
562 | src->badness = src->sticky_badness = 128; | |
563 | return (0.0); | |
564 | } | |
565 | } else if (WIFSIGNALED(status)) { | |
566 | debug2("Command '%s' returned on uncaught signal %d !", src->cmdstring, | |
567 | status); | |
568 | src->badness = src->sticky_badness = 128; | |
569 | return(0.0); | |
570 | } else | |
571 | return(0.0); | |
572 | } | |
573 | ||
574 | /* | |
575 | * prng seedfile functions | |
576 | */ | |
577 | int | |
578 | prng_check_seedfile(char *filename) { | |
579 | ||
580 | struct stat st; | |
581 | ||
582 | /* FIXME raceable: eg replace seed between this stat and subsequent open */ | |
583 | /* Not such a problem because we don't trust the seed file anyway */ | |
584 | if (lstat(filename, &st) == -1) { | |
585 | /* Give up on hard errors */ | |
586 | if (errno != ENOENT) | |
587 | debug("WARNING: Couldn't stat random seed file \"%s\": %s", | |
588 | filename, strerror(errno)); | |
589 | ||
590 | return(0); | |
591 | } | |
592 | ||
593 | /* regular file? */ | |
594 | if (!S_ISREG(st.st_mode)) | |
595 | fatal("PRNG seedfile %.100s is not a regular file", filename); | |
596 | ||
597 | /* mode 0600, owned by root or the current user? */ | |
598 | if (((st.st_mode & 0177) != 0) || !(st.st_uid == original_uid)) { | |
599 | debug("WARNING: PRNG seedfile %.100s must be mode 0600, owned by uid %d", | |
600 | filename, getuid()); | |
601 | return(0); | |
602 | } | |
603 | ||
604 | return(1); | |
605 | } | |
606 | ||
607 | void | |
608 | prng_write_seedfile(void) { | |
609 | int fd; | |
610 | char seed[1024]; | |
611 | char filename[1024]; | |
612 | struct passwd *pw; | |
613 | ||
614 | /* Don't bother if we have already saved a seed */ | |
615 | if (prng_seed_saved) | |
616 | return; | |
617 | ||
618 | setuid(original_uid); | |
619 | ||
620 | prng_seed_saved = 1; | |
621 | ||
622 | pw = getpwuid(original_uid); | |
623 | if (pw == NULL) | |
624 | fatal("Couldn't get password entry for current user (%i): %s", | |
625 | original_uid, strerror(errno)); | |
626 | ||
627 | /* Try to ensure that the parent directory is there */ | |
628 | snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir, | |
629 | _PATH_SSH_USER_DIR); | |
630 | mkdir(filename, 0700); | |
631 | ||
632 | snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir, | |
633 | SSH_PRNG_SEED_FILE); | |
634 | ||
635 | debug("writing PRNG seed to file %.100s", filename); | |
636 | ||
637 | RAND_bytes(seed, sizeof(seed)); | |
638 | ||
639 | /* Don't care if the seed doesn't exist */ | |
640 | prng_check_seedfile(filename); | |
641 | ||
642 | if ((fd = open(filename, O_WRONLY|O_TRUNC|O_CREAT, 0600)) == -1) { | |
643 | debug("WARNING: couldn't access PRNG seedfile %.100s (%.100s)", | |
644 | filename, strerror(errno)); | |
645 | } else { | |
646 | if (atomicio(write, fd, &seed, sizeof(seed)) != sizeof(seed)) | |
647 | fatal("problem writing PRNG seedfile %.100s (%.100s)", filename, | |
648 | strerror(errno)); | |
649 | ||
650 | close(fd); | |
651 | } | |
652 | } | |
653 | ||
654 | void | |
655 | prng_read_seedfile(void) { | |
656 | int fd; | |
657 | char seed[1024]; | |
658 | char filename[1024]; | |
659 | struct passwd *pw; | |
660 | ||
661 | pw = getpwuid(original_uid); | |
662 | if (pw == NULL) | |
663 | fatal("Couldn't get password entry for current user (%i): %s", | |
664 | original_uid, strerror(errno)); | |
665 | ||
666 | snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir, | |
667 | SSH_PRNG_SEED_FILE); | |
668 | ||
669 | debug("loading PRNG seed from file %.100s", filename); | |
670 | ||
671 | if (!prng_check_seedfile(filename)) { | |
672 | verbose("Random seed file not found or not valid, ignoring."); | |
673 | return; | |
674 | } | |
675 | ||
676 | /* open the file and read in the seed */ | |
677 | fd = open(filename, O_RDONLY); | |
678 | if (fd == -1) | |
679 | fatal("could not open PRNG seedfile %.100s (%.100s)", filename, | |
680 | strerror(errno)); | |
681 | ||
682 | if (atomicio(read, fd, &seed, sizeof(seed)) != sizeof(seed)) { | |
683 | verbose("invalid or short read from PRNG seedfile %.100s - ignoring", | |
684 | filename); | |
685 | memset(seed, '\0', sizeof(seed)); | |
686 | } | |
687 | close(fd); | |
688 | ||
689 | /* stir in the seed, with estimated entropy zero */ | |
690 | RAND_add(&seed, sizeof(seed), 0.0); | |
691 | } | |
692 | ||
693 | ||
694 | /* | |
695 | * entropy command initialisation functions | |
696 | */ | |
697 | int | |
698 | prng_read_commands(char *cmdfilename) | |
699 | { | |
700 | FILE *f; | |
701 | char *cp; | |
702 | char line[1024]; | |
703 | char cmd[1024]; | |
704 | char path[256]; | |
705 | int linenum; | |
706 | int num_cmds = 64; | |
707 | int cur_cmd = 0; | |
708 | double est; | |
709 | entropy_source_t *entcmd; | |
710 | ||
711 | f = fopen(cmdfilename, "r"); | |
712 | if (!f) { | |
713 | fatal("couldn't read entropy commands file %.100s: %.100s", | |
714 | cmdfilename, strerror(errno)); | |
715 | } | |
716 | ||
717 | entcmd = (entropy_source_t *)xmalloc(num_cmds * sizeof(entropy_source_t)); | |
718 | memset(entcmd, '\0', num_cmds * sizeof(entropy_source_t)); | |
719 | ||
720 | /* Read in file */ | |
721 | linenum = 0; | |
722 | while (fgets(line, sizeof(line), f)) { | |
723 | int arg; | |
724 | char *argv; | |
725 | ||
726 | linenum++; | |
727 | ||
728 | /* skip leading whitespace, test for blank line or comment */ | |
729 | cp = line + strspn(line, WHITESPACE); | |
730 | if ((*cp == 0) || (*cp == '#')) | |
731 | continue; /* done with this line */ | |
732 | ||
733 | /* First non-whitespace char should be double quote delimiting */ | |
734 | /* commandline */ | |
735 | if (*cp != '"') { | |
736 | error("bad entropy command, %.100s line %d", cmdfilename, | |
737 | linenum); | |
738 | continue; | |
739 | } | |
740 | ||
741 | /* first token, command args (incl. argv[0]) in double quotes */ | |
742 | cp = strtok(cp, "\""); | |
743 | if (cp == NULL) { | |
744 | error("missing or bad command string, %.100s line %d -- ignored", | |
745 | cmdfilename, linenum); | |
746 | continue; | |
747 | } | |
748 | strlcpy(cmd, cp, sizeof(cmd)); | |
749 | ||
750 | /* second token, full command path */ | |
751 | if ((cp = strtok(NULL, WHITESPACE)) == NULL) { | |
752 | error("missing command path, %.100s line %d -- ignored", | |
753 | cmdfilename, linenum); | |
754 | continue; | |
755 | } | |
756 | ||
757 | /* did configure mark this as dead? */ | |
758 | if (strncmp("undef", cp, 5) == 0) | |
759 | continue; | |
760 | ||
761 | strlcpy(path, cp, sizeof(path)); | |
762 | ||
763 | /* third token, entropy rate estimate for this command */ | |
764 | if ((cp = strtok(NULL, WHITESPACE)) == NULL) { | |
765 | error("missing entropy estimate, %.100s line %d -- ignored", | |
766 | cmdfilename, linenum); | |
767 | continue; | |
768 | } | |
769 | est = strtod(cp, &argv); | |
770 | ||
771 | /* end of line */ | |
772 | if ((cp = strtok(NULL, WHITESPACE)) != NULL) { | |
773 | error("garbage at end of line %d in %.100s -- ignored", linenum, | |
774 | cmdfilename); | |
775 | continue; | |
776 | } | |
777 | ||
778 | /* save the command for debug messages */ | |
779 | entcmd[cur_cmd].cmdstring = xstrdup(cmd); | |
780 | ||
781 | /* split the command args */ | |
782 | cp = strtok(cmd, WHITESPACE); | |
783 | arg = 0; | |
784 | argv = NULL; | |
785 | do { | |
786 | char *s = (char*)xmalloc(strlen(cp) + 1); | |
787 | strncpy(s, cp, strlen(cp) + 1); | |
788 | entcmd[cur_cmd].args[arg] = s; | |
789 | arg++; | |
790 | } while ((arg < 5) && (cp = strtok(NULL, WHITESPACE))); | |
791 | ||
792 | if (strtok(NULL, WHITESPACE)) | |
793 | error("ignored extra command elements (max 5), %.100s line %d", | |
794 | cmdfilename, linenum); | |
795 | ||
796 | /* Copy the command path and rate estimate */ | |
797 | entcmd[cur_cmd].path = xstrdup(path); | |
798 | entcmd[cur_cmd].rate = est; | |
799 | ||
800 | /* Initialise other values */ | |
801 | entcmd[cur_cmd].sticky_badness = 1; | |
802 | ||
803 | cur_cmd++; | |
804 | ||
805 | /* If we've filled the array, reallocate it twice the size */ | |
806 | /* Do this now because even if this we're on the last command, | |
807 | we need another slot to mark the last entry */ | |
808 | if (cur_cmd == num_cmds) { | |
809 | num_cmds *= 2; | |
810 | entcmd = xrealloc(entcmd, num_cmds * sizeof(entropy_source_t)); | |
811 | } | |
812 | } | |
813 | ||
814 | /* zero the last entry */ | |
815 | memset(&entcmd[cur_cmd], '\0', sizeof(entropy_source_t)); | |
816 | ||
817 | /* trim to size */ | |
818 | entropy_sources = xrealloc(entcmd, (cur_cmd+1) * sizeof(entropy_source_t)); | |
819 | ||
820 | debug("Loaded %d entropy commands from %.100s", cur_cmd, cmdfilename); | |
821 | ||
822 | return (cur_cmd >= MIN_ENTROPY_SOURCES); | |
823 | } | |
824 | ||
825 | /* | |
826 | * Write a keyfile at exit | |
827 | */ | |
828 | void | |
829 | prng_seed_cleanup(void *junk) | |
830 | { | |
831 | prng_write_seedfile(); | |
832 | } | |
833 | ||
834 | /* | |
835 | * Conditionally Seed OpenSSL's random number pool from | |
836 | * syscalls and program output | |
837 | */ | |
838 | void | |
839 | seed_rng(void) | |
840 | { | |
841 | mysig_t old_sigchld_handler; | |
842 | ||
843 | if (!prng_initialised) | |
844 | fatal("RNG not initialised"); | |
845 | ||
846 | /* Make sure some other sigchld handler doesn't reap our entropy */ | |
847 | /* commands */ | |
848 | old_sigchld_handler = mysignal(SIGCHLD, SIG_DFL); | |
849 | ||
850 | debug("Seeded RNG with %i bytes from programs", | |
851 | (int)stir_from_programs()); | |
852 | debug("Seeded RNG with %i bytes from system calls", | |
853 | (int)stir_from_system()); | |
854 | ||
855 | if (!RAND_status()) | |
856 | fatal("Not enough entropy in RNG"); | |
857 | ||
858 | mysignal(SIGCHLD, old_sigchld_handler); | |
859 | ||
860 | if (!RAND_status()) | |
861 | fatal("Couldn't initialise builtin random number generator -- exiting."); | |
862 | } | |
863 | ||
864 | void | |
865 | init_rng(void) | |
866 | { | |
867 | int original_euid; | |
868 | ||
869 | check_openssl_version(); | |
870 | ||
871 | original_uid = getuid(); | |
872 | original_euid = geteuid(); | |
873 | ||
874 | /* Read in collection commands */ | |
875 | if (!prng_read_commands(SSH_PRNG_COMMAND_FILE)) | |
876 | fatal("PRNG initialisation failed -- exiting."); | |
877 | ||
878 | /* Set ourselves up to save a seed upon exit */ | |
879 | prng_seed_saved = 0; | |
880 | ||
881 | /* Give up privs while reading seed file */ | |
882 | #ifdef SAVED_IDS_WORK_WITH_SETEUID | |
883 | if ((original_uid != original_euid) && (seteuid(original_uid) == -1)) | |
884 | fatal("Couldn't give up privileges"); | |
885 | #else /* SAVED_IDS_WORK_WITH_SETEUID */ | |
886 | /* | |
887 | * Propagate the privileged uid to all of our uids. | |
888 | * Set the effective uid to the given (unprivileged) uid. | |
889 | */ | |
890 | if (original_uid != original_euid && (setuid(original_euid) == -1 || | |
891 | seteuid(original_uid) == -1)) | |
892 | fatal("Couldn't give up privileges"); | |
893 | #endif /* SAVED_IDS_WORK_WITH_SETEUID */ | |
894 | ||
895 | prng_read_seedfile(); | |
896 | ||
897 | #ifdef SAVED_IDS_WORK_WITH_SETEUID | |
898 | if ((original_uid != original_euid) && (seteuid(original_euid) == -1)) | |
899 | fatal("Couldn't restore privileges"); | |
900 | #else /* SAVED_IDS_WORK_WITH_SETEUID */ | |
901 | /* | |
902 | * We are unable to restore the real uid to its unprivileged value. | |
903 | * Propagate the real uid (usually more privileged) to effective uid | |
904 | * as well. | |
905 | */ | |
906 | if (original_uid != original_euid && (seteuid(original_euid) == -1 || | |
907 | setuid(original_uid) == -1)) | |
908 | fatal("Couldn't restore privileges"); | |
909 | #endif /* SAVED_IDS_WORK_WITH_SETEUID */ | |
910 | ||
911 | fatal_add_cleanup(prng_seed_cleanup, NULL); | |
912 | atexit(prng_write_seedfile); | |
913 | ||
914 | prng_initialised = 1; | |
915 | } | |
916 | ||
917 | #endif /* defined(USE_PRNGD) || defined(RANDOM_POOL) */ |