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1 | /* | |
2 | * Copyright (c) 2001-2002 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 "misc.h" | |
37 | #include "xmalloc.h" | |
38 | #include "atomicio.h" | |
39 | #include "pathnames.h" | |
40 | #include "log.h" | |
41 | ||
42 | RCSID("$Id$"); | |
43 | ||
44 | /* Number of bytes we write out */ | |
45 | #define OUTPUT_SEED_SIZE 48 | |
46 | ||
47 | /* Length of on-disk seedfiles */ | |
48 | #define SEED_FILE_SIZE 1024 | |
49 | ||
50 | /* Maximum number of command-line arguments to read from file */ | |
51 | #define NUM_ARGS 10 | |
52 | ||
53 | /* Minimum number of usable commands to be considered sufficient */ | |
54 | #define MIN_ENTROPY_SOURCES 16 | |
55 | ||
56 | /* Path to on-disk seed file (relative to user's home directory */ | |
57 | #ifndef SSH_PRNG_SEED_FILE | |
58 | # define SSH_PRNG_SEED_FILE _PATH_SSH_USER_DIR"/prng_seed" | |
59 | #endif | |
60 | ||
61 | /* Path to PRNG commands list */ | |
62 | #ifndef SSH_PRNG_COMMAND_FILE | |
63 | # define SSH_PRNG_COMMAND_FILE SSHDIR "/ssh_prng_cmds" | |
64 | #endif | |
65 | ||
66 | extern char *__progname; | |
67 | ||
68 | #define WHITESPACE " \t\n" | |
69 | ||
70 | #ifndef RUSAGE_SELF | |
71 | # define RUSAGE_SELF 0 | |
72 | #endif | |
73 | #ifndef RUSAGE_CHILDREN | |
74 | # define RUSAGE_CHILDREN 0 | |
75 | #endif | |
76 | ||
77 | #if !defined(PRNGD_SOCKET) && !defined(PRNGD_PORT) | |
78 | # define USE_SEED_FILES | |
79 | #endif | |
80 | ||
81 | typedef struct { | |
82 | /* Proportion of data that is entropy */ | |
83 | double rate; | |
84 | /* Counter goes positive if this command times out */ | |
85 | unsigned int badness; | |
86 | /* Increases by factor of two each timeout */ | |
87 | unsigned int sticky_badness; | |
88 | /* Path to executable */ | |
89 | char *path; | |
90 | /* argv to pass to executable */ | |
91 | char *args[NUM_ARGS]; /* XXX: arbitrary limit */ | |
92 | /* full command string (debug) */ | |
93 | char *cmdstring; | |
94 | } entropy_cmd_t; | |
95 | ||
96 | /* slow command timeouts (all in milliseconds) */ | |
97 | /* static int entropy_timeout_default = ENTROPY_TIMEOUT_MSEC; */ | |
98 | static int entropy_timeout_current = ENTROPY_TIMEOUT_MSEC; | |
99 | ||
100 | /* this is initialised from a file, by prng_read_commands() */ | |
101 | static entropy_cmd_t *entropy_cmds = NULL; | |
102 | ||
103 | /* Prototypes */ | |
104 | double stir_from_system(void); | |
105 | double stir_from_programs(void); | |
106 | double stir_gettimeofday(double entropy_estimate); | |
107 | double stir_clock(double entropy_estimate); | |
108 | double stir_rusage(int who, double entropy_estimate); | |
109 | double hash_command_output(entropy_cmd_t *src, unsigned char *hash); | |
110 | int get_random_bytes_prngd(unsigned char *buf, int len, | |
111 | unsigned short tcp_port, char *socket_path); | |
112 | ||
113 | /* | |
114 | * Collect 'len' bytes of entropy into 'buf' from PRNGD/EGD daemon | |
115 | * listening either on 'tcp_port', or via Unix domain socket at * | |
116 | * 'socket_path'. | |
117 | * Either a non-zero tcp_port or a non-null socket_path must be | |
118 | * supplied. | |
119 | * Returns 0 on success, -1 on error | |
120 | */ | |
121 | int | |
122 | get_random_bytes_prngd(unsigned char *buf, int len, | |
123 | unsigned short tcp_port, char *socket_path) | |
124 | { | |
125 | int fd, addr_len, rval, errors; | |
126 | char msg[2]; | |
127 | struct sockaddr_storage addr; | |
128 | struct sockaddr_in *addr_in = (struct sockaddr_in *)&addr; | |
129 | struct sockaddr_un *addr_un = (struct sockaddr_un *)&addr; | |
130 | mysig_t old_sigpipe; | |
131 | ||
132 | /* Sanity checks */ | |
133 | if (socket_path == NULL && tcp_port == 0) | |
134 | fatal("You must specify a port or a socket"); | |
135 | if (socket_path != NULL && | |
136 | strlen(socket_path) >= sizeof(addr_un->sun_path)) | |
137 | fatal("Random pool path is too long"); | |
138 | if (len > 255) | |
139 | fatal("Too many bytes to read from PRNGD"); | |
140 | ||
141 | memset(&addr, '\0', sizeof(addr)); | |
142 | ||
143 | if (tcp_port != 0) { | |
144 | addr_in->sin_family = AF_INET; | |
145 | addr_in->sin_addr.s_addr = htonl(INADDR_LOOPBACK); | |
146 | addr_in->sin_port = htons(tcp_port); | |
147 | addr_len = sizeof(*addr_in); | |
148 | } else { | |
149 | addr_un->sun_family = AF_UNIX; | |
150 | strlcpy(addr_un->sun_path, socket_path, | |
151 | sizeof(addr_un->sun_path)); | |
152 | addr_len = offsetof(struct sockaddr_un, sun_path) + | |
153 | strlen(socket_path) + 1; | |
154 | } | |
155 | ||
156 | old_sigpipe = mysignal(SIGPIPE, SIG_IGN); | |
157 | ||
158 | errors = 0; | |
159 | rval = -1; | |
160 | reopen: | |
161 | fd = socket(addr.ss_family, SOCK_STREAM, 0); | |
162 | if (fd == -1) { | |
163 | error("Couldn't create socket: %s", strerror(errno)); | |
164 | goto done; | |
165 | } | |
166 | ||
167 | if (connect(fd, (struct sockaddr*)&addr, addr_len) == -1) { | |
168 | if (tcp_port != 0) { | |
169 | error("Couldn't connect to PRNGD port %d: %s", | |
170 | tcp_port, strerror(errno)); | |
171 | } else { | |
172 | error("Couldn't connect to PRNGD socket \"%s\": %s", | |
173 | addr_un->sun_path, strerror(errno)); | |
174 | } | |
175 | goto done; | |
176 | } | |
177 | ||
178 | /* Send blocking read request to PRNGD */ | |
179 | msg[0] = 0x02; | |
180 | msg[1] = len; | |
181 | ||
182 | if (atomicio(vwrite, fd, msg, sizeof(msg)) != sizeof(msg)) { | |
183 | if (errno == EPIPE && errors < 10) { | |
184 | close(fd); | |
185 | errors++; | |
186 | goto reopen; | |
187 | } | |
188 | error("Couldn't write to PRNGD socket: %s", | |
189 | strerror(errno)); | |
190 | goto done; | |
191 | } | |
192 | ||
193 | if (atomicio(read, fd, buf, len) != len) { | |
194 | if (errno == EPIPE && errors < 10) { | |
195 | close(fd); | |
196 | errors++; | |
197 | goto reopen; | |
198 | } | |
199 | error("Couldn't read from PRNGD socket: %s", | |
200 | strerror(errno)); | |
201 | goto done; | |
202 | } | |
203 | ||
204 | rval = 0; | |
205 | done: | |
206 | mysignal(SIGPIPE, old_sigpipe); | |
207 | if (fd != -1) | |
208 | close(fd); | |
209 | return rval; | |
210 | } | |
211 | ||
212 | static int | |
213 | seed_from_prngd(unsigned char *buf, size_t bytes) | |
214 | { | |
215 | #ifdef PRNGD_PORT | |
216 | debug("trying egd/prngd port %d", PRNGD_PORT); | |
217 | if (get_random_bytes_prngd(buf, bytes, PRNGD_PORT, NULL) == 0) | |
218 | return 0; | |
219 | #endif | |
220 | #ifdef PRNGD_SOCKET | |
221 | debug("trying egd/prngd socket %s", PRNGD_SOCKET); | |
222 | if (get_random_bytes_prngd(buf, bytes, 0, PRNGD_SOCKET) == 0) | |
223 | return 0; | |
224 | #endif | |
225 | return -1; | |
226 | } | |
227 | ||
228 | double | |
229 | stir_gettimeofday(double entropy_estimate) | |
230 | { | |
231 | struct timeval tv; | |
232 | ||
233 | if (gettimeofday(&tv, NULL) == -1) | |
234 | fatal("Couldn't gettimeofday: %s", strerror(errno)); | |
235 | ||
236 | RAND_add(&tv, sizeof(tv), entropy_estimate); | |
237 | ||
238 | return entropy_estimate; | |
239 | } | |
240 | ||
241 | double | |
242 | stir_clock(double entropy_estimate) | |
243 | { | |
244 | #ifdef HAVE_CLOCK | |
245 | clock_t c; | |
246 | ||
247 | c = clock(); | |
248 | RAND_add(&c, sizeof(c), entropy_estimate); | |
249 | ||
250 | return entropy_estimate; | |
251 | #else /* _HAVE_CLOCK */ | |
252 | return 0; | |
253 | #endif /* _HAVE_CLOCK */ | |
254 | } | |
255 | ||
256 | double | |
257 | stir_rusage(int who, double entropy_estimate) | |
258 | { | |
259 | #ifdef HAVE_GETRUSAGE | |
260 | struct rusage ru; | |
261 | ||
262 | if (getrusage(who, &ru) == -1) | |
263 | return 0; | |
264 | ||
265 | RAND_add(&ru, sizeof(ru), entropy_estimate); | |
266 | ||
267 | return entropy_estimate; | |
268 | #else /* _HAVE_GETRUSAGE */ | |
269 | return 0; | |
270 | #endif /* _HAVE_GETRUSAGE */ | |
271 | } | |
272 | ||
273 | static int | |
274 | timeval_diff(struct timeval *t1, struct timeval *t2) | |
275 | { | |
276 | int secdiff, usecdiff; | |
277 | ||
278 | secdiff = t2->tv_sec - t1->tv_sec; | |
279 | usecdiff = (secdiff*1000000) + (t2->tv_usec - t1->tv_usec); | |
280 | return (int)(usecdiff / 1000); | |
281 | } | |
282 | ||
283 | double | |
284 | hash_command_output(entropy_cmd_t *src, unsigned char *hash) | |
285 | { | |
286 | char buf[8192]; | |
287 | fd_set rdset; | |
288 | int bytes_read, cmd_eof, error_abort, msec_elapsed, p[2]; | |
289 | int status, total_bytes_read; | |
290 | static int devnull = -1; | |
291 | pid_t pid; | |
292 | SHA_CTX sha; | |
293 | struct timeval tv_start, tv_current; | |
294 | ||
295 | debug3("Reading output from \'%s\'", src->cmdstring); | |
296 | ||
297 | if (devnull == -1) { | |
298 | devnull = open("/dev/null", O_RDWR); | |
299 | if (devnull == -1) | |
300 | fatal("Couldn't open /dev/null: %s", | |
301 | strerror(errno)); | |
302 | } | |
303 | ||
304 | if (pipe(p) == -1) | |
305 | fatal("Couldn't open pipe: %s", strerror(errno)); | |
306 | ||
307 | (void)gettimeofday(&tv_start, NULL); /* record start time */ | |
308 | ||
309 | switch (pid = fork()) { | |
310 | case -1: /* Error */ | |
311 | close(p[0]); | |
312 | close(p[1]); | |
313 | fatal("Couldn't fork: %s", strerror(errno)); | |
314 | /* NOTREACHED */ | |
315 | case 0: /* Child */ | |
316 | dup2(devnull, STDIN_FILENO); | |
317 | dup2(p[1], STDOUT_FILENO); | |
318 | dup2(p[1], STDERR_FILENO); | |
319 | close(p[0]); | |
320 | close(p[1]); | |
321 | close(devnull); | |
322 | ||
323 | execv(src->path, (char**)(src->args)); | |
324 | ||
325 | debug("(child) Couldn't exec '%s': %s", | |
326 | src->cmdstring, strerror(errno)); | |
327 | _exit(-1); | |
328 | default: /* Parent */ | |
329 | break; | |
330 | } | |
331 | ||
332 | RAND_add(&pid, sizeof(&pid), 0.0); | |
333 | ||
334 | close(p[1]); | |
335 | ||
336 | /* Hash output from child */ | |
337 | SHA1_Init(&sha); | |
338 | ||
339 | cmd_eof = error_abort = msec_elapsed = total_bytes_read = 0; | |
340 | while (!error_abort && !cmd_eof) { | |
341 | int ret; | |
342 | struct timeval tv; | |
343 | int msec_remaining; | |
344 | ||
345 | (void) gettimeofday(&tv_current, 0); | |
346 | msec_elapsed = timeval_diff(&tv_start, &tv_current); | |
347 | if (msec_elapsed >= entropy_timeout_current) { | |
348 | error_abort=1; | |
349 | continue; | |
350 | } | |
351 | msec_remaining = entropy_timeout_current - msec_elapsed; | |
352 | ||
353 | FD_ZERO(&rdset); | |
354 | FD_SET(p[0], &rdset); | |
355 | tv.tv_sec = msec_remaining / 1000; | |
356 | tv.tv_usec = (msec_remaining % 1000) * 1000; | |
357 | ||
358 | ret = select(p[0] + 1, &rdset, NULL, NULL, &tv); | |
359 | ||
360 | RAND_add(&tv, sizeof(tv), 0.0); | |
361 | ||
362 | switch (ret) { | |
363 | case 0: | |
364 | /* timer expired */ | |
365 | error_abort = 1; | |
366 | kill(pid, SIGINT); | |
367 | break; | |
368 | case 1: | |
369 | /* command input */ | |
370 | do { | |
371 | bytes_read = read(p[0], buf, sizeof(buf)); | |
372 | } while (bytes_read == -1 && errno == EINTR); | |
373 | RAND_add(&bytes_read, sizeof(&bytes_read), 0.0); | |
374 | if (bytes_read == -1) { | |
375 | error_abort = 1; | |
376 | break; | |
377 | } else if (bytes_read) { | |
378 | SHA1_Update(&sha, buf, bytes_read); | |
379 | total_bytes_read += bytes_read; | |
380 | } else { | |
381 | cmd_eof = 1; | |
382 | } | |
383 | break; | |
384 | case -1: | |
385 | default: | |
386 | /* error */ | |
387 | debug("Command '%s': select() failed: %s", | |
388 | src->cmdstring, strerror(errno)); | |
389 | error_abort = 1; | |
390 | break; | |
391 | } | |
392 | } | |
393 | ||
394 | SHA1_Final(hash, &sha); | |
395 | ||
396 | close(p[0]); | |
397 | ||
398 | debug3("Time elapsed: %d msec", msec_elapsed); | |
399 | ||
400 | if (waitpid(pid, &status, 0) == -1) { | |
401 | error("Couldn't wait for child '%s' completion: %s", | |
402 | src->cmdstring, strerror(errno)); | |
403 | return 0.0; | |
404 | } | |
405 | ||
406 | RAND_add(&status, sizeof(&status), 0.0); | |
407 | ||
408 | if (error_abort) { | |
409 | /* | |
410 | * Closing p[0] on timeout causes the entropy command to | |
411 | * SIGPIPE. Take whatever output we got, and mark this | |
412 | * command as slow | |
413 | */ | |
414 | debug2("Command '%s' timed out", src->cmdstring); | |
415 | src->sticky_badness *= 2; | |
416 | src->badness = src->sticky_badness; | |
417 | return total_bytes_read; | |
418 | } | |
419 | ||
420 | if (WIFEXITED(status)) { | |
421 | if (WEXITSTATUS(status) == 0) { | |
422 | return total_bytes_read; | |
423 | } else { | |
424 | debug2("Command '%s' exit status was %d", | |
425 | src->cmdstring, WEXITSTATUS(status)); | |
426 | src->badness = src->sticky_badness = 128; | |
427 | return 0.0; | |
428 | } | |
429 | } else if (WIFSIGNALED(status)) { | |
430 | debug2("Command '%s' returned on uncaught signal %d !", | |
431 | src->cmdstring, status); | |
432 | src->badness = src->sticky_badness = 128; | |
433 | return 0.0; | |
434 | } else | |
435 | return 0.0; | |
436 | } | |
437 | ||
438 | double | |
439 | stir_from_system(void) | |
440 | { | |
441 | double total_entropy_estimate; | |
442 | long int i; | |
443 | ||
444 | total_entropy_estimate = 0; | |
445 | ||
446 | i = getpid(); | |
447 | RAND_add(&i, sizeof(i), 0.5); | |
448 | total_entropy_estimate += 0.1; | |
449 | ||
450 | i = getppid(); | |
451 | RAND_add(&i, sizeof(i), 0.5); | |
452 | total_entropy_estimate += 0.1; | |
453 | ||
454 | i = getuid(); | |
455 | RAND_add(&i, sizeof(i), 0.0); | |
456 | i = getgid(); | |
457 | RAND_add(&i, sizeof(i), 0.0); | |
458 | ||
459 | total_entropy_estimate += stir_gettimeofday(1.0); | |
460 | total_entropy_estimate += stir_clock(0.5); | |
461 | total_entropy_estimate += stir_rusage(RUSAGE_SELF, 2.0); | |
462 | ||
463 | return total_entropy_estimate; | |
464 | } | |
465 | ||
466 | double | |
467 | stir_from_programs(void) | |
468 | { | |
469 | int c; | |
470 | double entropy, total_entropy; | |
471 | unsigned char hash[SHA_DIGEST_LENGTH]; | |
472 | ||
473 | total_entropy = 0; | |
474 | for(c = 0; entropy_cmds[c].path != NULL; c++) { | |
475 | if (!entropy_cmds[c].badness) { | |
476 | /* Hash output from command */ | |
477 | entropy = hash_command_output(&entropy_cmds[c], | |
478 | hash); | |
479 | ||
480 | /* Scale back estimate by command's rate */ | |
481 | entropy *= entropy_cmds[c].rate; | |
482 | ||
483 | /* Upper bound of entropy is SHA_DIGEST_LENGTH */ | |
484 | if (entropy > SHA_DIGEST_LENGTH) | |
485 | entropy = SHA_DIGEST_LENGTH; | |
486 | ||
487 | /* Stir it in */ | |
488 | RAND_add(hash, sizeof(hash), entropy); | |
489 | ||
490 | debug3("Got %0.2f bytes of entropy from '%s'", | |
491 | entropy, entropy_cmds[c].cmdstring); | |
492 | ||
493 | total_entropy += entropy; | |
494 | ||
495 | /* Execution time should be a bit unpredictable */ | |
496 | total_entropy += stir_gettimeofday(0.05); | |
497 | total_entropy += stir_clock(0.05); | |
498 | total_entropy += stir_rusage(RUSAGE_SELF, 0.1); | |
499 | total_entropy += stir_rusage(RUSAGE_CHILDREN, 0.1); | |
500 | } else { | |
501 | debug2("Command '%s' disabled (badness %d)", | |
502 | entropy_cmds[c].cmdstring, | |
503 | entropy_cmds[c].badness); | |
504 | ||
505 | if (entropy_cmds[c].badness > 0) | |
506 | entropy_cmds[c].badness--; | |
507 | } | |
508 | } | |
509 | ||
510 | return total_entropy; | |
511 | } | |
512 | ||
513 | /* | |
514 | * prng seedfile functions | |
515 | */ | |
516 | int | |
517 | prng_check_seedfile(char *filename) | |
518 | { | |
519 | struct stat st; | |
520 | ||
521 | /* | |
522 | * XXX raceable: eg replace seed between this stat and subsequent | |
523 | * open. Not such a problem because we don't really trust the | |
524 | * seed file anyway. | |
525 | * XXX: use secure path checking as elsewhere in OpenSSH | |
526 | */ | |
527 | if (lstat(filename, &st) == -1) { | |
528 | /* Give up on hard errors */ | |
529 | if (errno != ENOENT) | |
530 | debug("WARNING: Couldn't stat random seed file " | |
531 | "\"%.100s\": %s", filename, strerror(errno)); | |
532 | return 0; | |
533 | } | |
534 | ||
535 | /* regular file? */ | |
536 | if (!S_ISREG(st.st_mode)) | |
537 | fatal("PRNG seedfile %.100s is not a regular file", | |
538 | filename); | |
539 | ||
540 | /* mode 0600, owned by root or the current user? */ | |
541 | if (((st.st_mode & 0177) != 0) || !(st.st_uid == getuid())) { | |
542 | debug("WARNING: PRNG seedfile %.100s must be mode 0600, " | |
543 | "owned by uid %li", filename, (long int)getuid()); | |
544 | return 0; | |
545 | } | |
546 | ||
547 | return 1; | |
548 | } | |
549 | ||
550 | void | |
551 | prng_write_seedfile(void) | |
552 | { | |
553 | int fd, save_errno; | |
554 | unsigned char seed[SEED_FILE_SIZE]; | |
555 | char filename[MAXPATHLEN], tmpseed[MAXPATHLEN]; | |
556 | struct passwd *pw; | |
557 | mode_t old_umask; | |
558 | ||
559 | pw = getpwuid(getuid()); | |
560 | if (pw == NULL) | |
561 | fatal("Couldn't get password entry for current user " | |
562 | "(%li): %s", (long int)getuid(), strerror(errno)); | |
563 | ||
564 | /* Try to ensure that the parent directory is there */ | |
565 | snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir, | |
566 | _PATH_SSH_USER_DIR); | |
567 | mkdir(filename, 0700); | |
568 | ||
569 | snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir, | |
570 | SSH_PRNG_SEED_FILE); | |
571 | ||
572 | strlcpy(tmpseed, filename, sizeof(tmpseed)); | |
573 | if (strlcat(tmpseed, ".XXXXXXXXXX", sizeof(tmpseed)) >= | |
574 | sizeof(tmpseed)) | |
575 | fatal("PRNG seed filename too long"); | |
576 | ||
577 | if (RAND_bytes(seed, sizeof(seed)) <= 0) | |
578 | fatal("PRNG seed extraction failed"); | |
579 | ||
580 | /* Don't care if the seed doesn't exist */ | |
581 | prng_check_seedfile(filename); | |
582 | ||
583 | old_umask = umask(0177); | |
584 | ||
585 | if ((fd = mkstemp(tmpseed)) == -1) { | |
586 | debug("WARNING: couldn't make temporary PRNG seedfile %.100s " | |
587 | "(%.100s)", tmpseed, strerror(errno)); | |
588 | } else { | |
589 | debug("writing PRNG seed to file %.100s", tmpseed); | |
590 | if (atomicio(vwrite, fd, &seed, sizeof(seed)) < sizeof(seed)) { | |
591 | save_errno = errno; | |
592 | close(fd); | |
593 | unlink(tmpseed); | |
594 | fatal("problem writing PRNG seedfile %.100s " | |
595 | "(%.100s)", filename, strerror(save_errno)); | |
596 | } | |
597 | close(fd); | |
598 | debug("moving temporary PRNG seed to file %.100s", filename); | |
599 | if (rename(tmpseed, filename) == -1) { | |
600 | save_errno = errno; | |
601 | unlink(tmpseed); | |
602 | fatal("problem renaming PRNG seedfile from %.100s " | |
603 | "to %.100s (%.100s)", tmpseed, filename, | |
604 | strerror(save_errno)); | |
605 | } | |
606 | } | |
607 | umask(old_umask); | |
608 | } | |
609 | ||
610 | void | |
611 | prng_read_seedfile(void) | |
612 | { | |
613 | int fd; | |
614 | char seed[SEED_FILE_SIZE], filename[MAXPATHLEN]; | |
615 | struct passwd *pw; | |
616 | ||
617 | pw = getpwuid(getuid()); | |
618 | if (pw == NULL) | |
619 | fatal("Couldn't get password entry for current user " | |
620 | "(%li): %s", (long int)getuid(), strerror(errno)); | |
621 | ||
622 | snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir, | |
623 | SSH_PRNG_SEED_FILE); | |
624 | ||
625 | debug("loading PRNG seed from file %.100s", filename); | |
626 | ||
627 | if (!prng_check_seedfile(filename)) { | |
628 | verbose("Random seed file not found or invalid, ignoring."); | |
629 | return; | |
630 | } | |
631 | ||
632 | /* open the file and read in the seed */ | |
633 | fd = open(filename, O_RDONLY); | |
634 | if (fd == -1) | |
635 | fatal("could not open PRNG seedfile %.100s (%.100s)", | |
636 | filename, strerror(errno)); | |
637 | ||
638 | if (atomicio(read, fd, &seed, sizeof(seed)) < sizeof(seed)) { | |
639 | verbose("invalid or short read from PRNG seedfile " | |
640 | "%.100s - ignoring", filename); | |
641 | memset(seed, '\0', sizeof(seed)); | |
642 | } | |
643 | close(fd); | |
644 | ||
645 | /* stir in the seed, with estimated entropy zero */ | |
646 | RAND_add(&seed, sizeof(seed), 0.0); | |
647 | } | |
648 | ||
649 | ||
650 | /* | |
651 | * entropy command initialisation functions | |
652 | */ | |
653 | int | |
654 | prng_read_commands(char *cmdfilename) | |
655 | { | |
656 | char cmd[SEED_FILE_SIZE], *cp, line[1024], path[SEED_FILE_SIZE]; | |
657 | double est; | |
658 | entropy_cmd_t *entcmd; | |
659 | FILE *f; | |
660 | int cur_cmd, linenum, num_cmds, arg; | |
661 | ||
662 | if ((f = fopen(cmdfilename, "r")) == NULL) { | |
663 | fatal("couldn't read entropy commands file %.100s: %.100s", | |
664 | cmdfilename, strerror(errno)); | |
665 | } | |
666 | ||
667 | num_cmds = 64; | |
668 | entcmd = xmalloc(num_cmds * sizeof(entropy_cmd_t)); | |
669 | memset(entcmd, '\0', num_cmds * sizeof(entropy_cmd_t)); | |
670 | ||
671 | /* Read in file */ | |
672 | cur_cmd = linenum = 0; | |
673 | while (fgets(line, sizeof(line), f)) { | |
674 | linenum++; | |
675 | ||
676 | /* Skip leading whitespace, blank lines and comments */ | |
677 | cp = line + strspn(line, WHITESPACE); | |
678 | if ((*cp == 0) || (*cp == '#')) | |
679 | continue; /* done with this line */ | |
680 | ||
681 | /* | |
682 | * The first non-whitespace char should be a double quote | |
683 | * delimiting the commandline | |
684 | */ | |
685 | if (*cp != '"') { | |
686 | error("bad entropy command, %.100s line %d", | |
687 | cmdfilename, linenum); | |
688 | continue; | |
689 | } | |
690 | ||
691 | /* | |
692 | * First token, command args (incl. argv[0]) in double | |
693 | * quotes | |
694 | */ | |
695 | cp = strtok(cp, "\""); | |
696 | if (cp == NULL) { | |
697 | error("missing or bad command string, %.100s " | |
698 | "line %d -- ignored", cmdfilename, linenum); | |
699 | continue; | |
700 | } | |
701 | strlcpy(cmd, cp, sizeof(cmd)); | |
702 | ||
703 | /* Second token, full command path */ | |
704 | if ((cp = strtok(NULL, WHITESPACE)) == NULL) { | |
705 | error("missing command path, %.100s " | |
706 | "line %d -- ignored", cmdfilename, linenum); | |
707 | continue; | |
708 | } | |
709 | ||
710 | /* Did configure mark this as dead? */ | |
711 | if (strncmp("undef", cp, 5) == 0) | |
712 | continue; | |
713 | ||
714 | strlcpy(path, cp, sizeof(path)); | |
715 | ||
716 | /* Third token, entropy rate estimate for this command */ | |
717 | if ((cp = strtok(NULL, WHITESPACE)) == NULL) { | |
718 | error("missing entropy estimate, %.100s " | |
719 | "line %d -- ignored", cmdfilename, linenum); | |
720 | continue; | |
721 | } | |
722 | est = strtod(cp, NULL); | |
723 | ||
724 | /* end of line */ | |
725 | if ((cp = strtok(NULL, WHITESPACE)) != NULL) { | |
726 | error("garbage at end of line %d in %.100s " | |
727 | "-- ignored", linenum, cmdfilename); | |
728 | continue; | |
729 | } | |
730 | ||
731 | /* save the command for debug messages */ | |
732 | entcmd[cur_cmd].cmdstring = xstrdup(cmd); | |
733 | ||
734 | /* split the command args */ | |
735 | cp = strtok(cmd, WHITESPACE); | |
736 | arg = 0; | |
737 | do { | |
738 | entcmd[cur_cmd].args[arg] = xstrdup(cp); | |
739 | arg++; | |
740 | } while(arg < NUM_ARGS && (cp = strtok(NULL, WHITESPACE))); | |
741 | ||
742 | if (strtok(NULL, WHITESPACE)) | |
743 | error("ignored extra commands (max %d), %.100s " | |
744 | "line %d", NUM_ARGS, cmdfilename, linenum); | |
745 | ||
746 | /* Copy the command path and rate estimate */ | |
747 | entcmd[cur_cmd].path = xstrdup(path); | |
748 | entcmd[cur_cmd].rate = est; | |
749 | ||
750 | /* Initialise other values */ | |
751 | entcmd[cur_cmd].sticky_badness = 1; | |
752 | ||
753 | cur_cmd++; | |
754 | ||
755 | /* | |
756 | * If we've filled the array, reallocate it twice the size | |
757 | * Do this now because even if this we're on the last | |
758 | * command we need another slot to mark the last entry | |
759 | */ | |
760 | if (cur_cmd == num_cmds) { | |
761 | num_cmds *= 2; | |
762 | entcmd = xrealloc(entcmd, num_cmds * | |
763 | sizeof(entropy_cmd_t)); | |
764 | } | |
765 | } | |
766 | ||
767 | /* zero the last entry */ | |
768 | memset(&entcmd[cur_cmd], '\0', sizeof(entropy_cmd_t)); | |
769 | ||
770 | /* trim to size */ | |
771 | entropy_cmds = xrealloc(entcmd, (cur_cmd + 1) * | |
772 | sizeof(entropy_cmd_t)); | |
773 | ||
774 | debug("Loaded %d entropy commands from %.100s", cur_cmd, | |
775 | cmdfilename); | |
776 | ||
777 | return cur_cmd < MIN_ENTROPY_SOURCES ? -1 : 0; | |
778 | } | |
779 | ||
780 | void | |
781 | usage(void) | |
782 | { | |
783 | fprintf(stderr, "Usage: %s [options]\n", __progname); | |
784 | fprintf(stderr, " -v Verbose; display verbose debugging messages.\n"); | |
785 | fprintf(stderr, " Multiple -v increases verbosity.\n"); | |
786 | fprintf(stderr, " -x Force output in hexadecimal (for debugging)\n"); | |
787 | fprintf(stderr, " -X Force output in binary\n"); | |
788 | fprintf(stderr, " -b bytes Number of bytes to output (default %d)\n", | |
789 | OUTPUT_SEED_SIZE); | |
790 | } | |
791 | ||
792 | int | |
793 | main(int argc, char **argv) | |
794 | { | |
795 | unsigned char *buf; | |
796 | int ret, ch, debug_level, output_hex, bytes; | |
797 | extern char *optarg; | |
798 | LogLevel ll; | |
799 | ||
800 | __progname = ssh_get_progname(argv[0]); | |
801 | log_init(argv[0], SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_USER, 1); | |
802 | ||
803 | ll = SYSLOG_LEVEL_INFO; | |
804 | debug_level = output_hex = 0; | |
805 | bytes = OUTPUT_SEED_SIZE; | |
806 | ||
807 | /* Don't write binary data to a tty, unless we are forced to */ | |
808 | if (isatty(STDOUT_FILENO)) | |
809 | output_hex = 1; | |
810 | ||
811 | while ((ch = getopt(argc, argv, "vxXhb:")) != -1) { | |
812 | switch (ch) { | |
813 | case 'v': | |
814 | if (debug_level < 3) | |
815 | ll = SYSLOG_LEVEL_DEBUG1 + debug_level++; | |
816 | break; | |
817 | case 'x': | |
818 | output_hex = 1; | |
819 | break; | |
820 | case 'X': | |
821 | output_hex = 0; | |
822 | break; | |
823 | case 'b': | |
824 | if ((bytes = atoi(optarg)) <= 0) | |
825 | fatal("Invalid number of output bytes"); | |
826 | break; | |
827 | case 'h': | |
828 | usage(); | |
829 | exit(0); | |
830 | default: | |
831 | error("Invalid commandline option"); | |
832 | usage(); | |
833 | } | |
834 | } | |
835 | ||
836 | log_init(argv[0], ll, SYSLOG_FACILITY_USER, 1); | |
837 | ||
838 | #ifdef USE_SEED_FILES | |
839 | prng_read_seedfile(); | |
840 | #endif | |
841 | ||
842 | buf = xmalloc(bytes); | |
843 | ||
844 | /* | |
845 | * Seed the RNG from wherever we can | |
846 | */ | |
847 | ||
848 | /* Take whatever is on the stack, but don't credit it */ | |
849 | RAND_add(buf, bytes, 0); | |
850 | ||
851 | debug("Seeded RNG with %i bytes from system calls", | |
852 | (int)stir_from_system()); | |
853 | ||
854 | /* try prngd, fall back to commands if prngd fails or not configured */ | |
855 | if (seed_from_prngd(buf, bytes) == 0) { | |
856 | RAND_add(buf, bytes, bytes); | |
857 | } else { | |
858 | /* Read in collection commands */ | |
859 | if (prng_read_commands(SSH_PRNG_COMMAND_FILE) == -1) | |
860 | fatal("PRNG initialisation failed -- exiting."); | |
861 | debug("Seeded RNG with %i bytes from programs", | |
862 | (int)stir_from_programs()); | |
863 | } | |
864 | ||
865 | #ifdef USE_SEED_FILES | |
866 | prng_write_seedfile(); | |
867 | #endif | |
868 | ||
869 | /* | |
870 | * Write the seed to stdout | |
871 | */ | |
872 | ||
873 | if (!RAND_status()) | |
874 | fatal("Not enough entropy in RNG"); | |
875 | ||
876 | if (RAND_bytes(buf, bytes) <= 0) | |
877 | fatal("Couldn't extract entropy from PRNG"); | |
878 | ||
879 | if (output_hex) { | |
880 | for(ret = 0; ret < bytes; ret++) | |
881 | printf("%02x", (unsigned char)(buf[ret])); | |
882 | printf("\n"); | |
883 | } else | |
884 | ret = atomicio(vwrite, STDOUT_FILENO, buf, bytes); | |
885 | ||
886 | memset(buf, '\0', bytes); | |
887 | xfree(buf); | |
888 | ||
889 | return ret == bytes ? 0 : 1; | |
890 | } | |
891 | ||
892 | /* | |
893 | * We may attempt to re-seed during mkstemp if we are using the one in the | |
894 | * compat library (via mkstemp -> _gettemp -> arc4random -> seed_rng) so we | |
895 | * need our own seed_rng(). We must also check that we have enough entropy. | |
896 | */ | |
897 | void | |
898 | seed_rng(void) | |
899 | { | |
900 | if (!RAND_status()) | |
901 | fatal("Not enough entropy in RNG"); | |
902 | } |