]>
Commit | Line | Data |
---|---|---|
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 <sys/types.h> | |
28 | #include <sys/resource.h> | |
29 | #include <sys/stat.h> | |
30 | #include <sys/wait.h> | |
31 | #include <sys/socket.h> | |
32 | ||
33 | #include <netinet/in.h> | |
34 | ||
35 | #ifdef HAVE_SYS_UN_H | |
36 | # include <sys/un.h> | |
37 | #endif | |
38 | ||
39 | #include <errno.h> | |
40 | #include <fcntl.h> | |
41 | #include <pwd.h> | |
42 | #include <signal.h> | |
43 | ||
44 | #include <openssl/rand.h> | |
45 | #include <openssl/sha.h> | |
46 | #include <openssl/crypto.h> | |
47 | ||
48 | /* SunOS 4.4.4 needs this */ | |
49 | #ifdef HAVE_FLOATINGPOINT_H | |
50 | # include <floatingpoint.h> | |
51 | #endif /* HAVE_FLOATINGPOINT_H */ | |
52 | ||
53 | #include "misc.h" | |
54 | #include "xmalloc.h" | |
55 | #include "atomicio.h" | |
56 | #include "pathnames.h" | |
57 | #include "log.h" | |
58 | ||
59 | /* Number of bytes we write out */ | |
60 | #define OUTPUT_SEED_SIZE 48 | |
61 | ||
62 | /* Length of on-disk seedfiles */ | |
63 | #define SEED_FILE_SIZE 1024 | |
64 | ||
65 | /* Maximum number of command-line arguments to read from file */ | |
66 | #define NUM_ARGS 10 | |
67 | ||
68 | /* Minimum number of usable commands to be considered sufficient */ | |
69 | #define MIN_ENTROPY_SOURCES 16 | |
70 | ||
71 | /* Path to on-disk seed file (relative to user's home directory */ | |
72 | #ifndef SSH_PRNG_SEED_FILE | |
73 | # define SSH_PRNG_SEED_FILE _PATH_SSH_USER_DIR"/prng_seed" | |
74 | #endif | |
75 | ||
76 | /* Path to PRNG commands list */ | |
77 | #ifndef SSH_PRNG_COMMAND_FILE | |
78 | # define SSH_PRNG_COMMAND_FILE SSHDIR "/ssh_prng_cmds" | |
79 | #endif | |
80 | ||
81 | extern char *__progname; | |
82 | ||
83 | #define WHITESPACE " \t\n" | |
84 | ||
85 | #ifndef RUSAGE_SELF | |
86 | # define RUSAGE_SELF 0 | |
87 | #endif | |
88 | #ifndef RUSAGE_CHILDREN | |
89 | # define RUSAGE_CHILDREN 0 | |
90 | #endif | |
91 | ||
92 | #if !defined(PRNGD_SOCKET) && !defined(PRNGD_PORT) | |
93 | # define USE_SEED_FILES | |
94 | #endif | |
95 | ||
96 | typedef struct { | |
97 | /* Proportion of data that is entropy */ | |
98 | double rate; | |
99 | /* Counter goes positive if this command times out */ | |
100 | unsigned int badness; | |
101 | /* Increases by factor of two each timeout */ | |
102 | unsigned int sticky_badness; | |
103 | /* Path to executable */ | |
104 | char *path; | |
105 | /* argv to pass to executable */ | |
106 | char *args[NUM_ARGS]; /* XXX: arbitrary limit */ | |
107 | /* full command string (debug) */ | |
108 | char *cmdstring; | |
109 | } entropy_cmd_t; | |
110 | ||
111 | /* slow command timeouts (all in milliseconds) */ | |
112 | /* static int entropy_timeout_default = ENTROPY_TIMEOUT_MSEC; */ | |
113 | static int entropy_timeout_current = ENTROPY_TIMEOUT_MSEC; | |
114 | ||
115 | /* this is initialised from a file, by prng_read_commands() */ | |
116 | static entropy_cmd_t *entropy_cmds = NULL; | |
117 | ||
118 | /* Prototypes */ | |
119 | double stir_from_system(void); | |
120 | double stir_from_programs(void); | |
121 | double stir_gettimeofday(double entropy_estimate); | |
122 | double stir_clock(double entropy_estimate); | |
123 | double stir_rusage(int who, double entropy_estimate); | |
124 | double hash_command_output(entropy_cmd_t *src, unsigned char *hash); | |
125 | int get_random_bytes_prngd(unsigned char *buf, int len, | |
126 | unsigned short tcp_port, char *socket_path); | |
127 | ||
128 | /* | |
129 | * Collect 'len' bytes of entropy into 'buf' from PRNGD/EGD daemon | |
130 | * listening either on 'tcp_port', or via Unix domain socket at * | |
131 | * 'socket_path'. | |
132 | * Either a non-zero tcp_port or a non-null socket_path must be | |
133 | * supplied. | |
134 | * Returns 0 on success, -1 on error | |
135 | */ | |
136 | int | |
137 | get_random_bytes_prngd(unsigned char *buf, int len, | |
138 | unsigned short tcp_port, char *socket_path) | |
139 | { | |
140 | int fd, addr_len, rval, errors; | |
141 | u_char msg[2]; | |
142 | struct sockaddr_storage addr; | |
143 | struct sockaddr_in *addr_in = (struct sockaddr_in *)&addr; | |
144 | struct sockaddr_un *addr_un = (struct sockaddr_un *)&addr; | |
145 | mysig_t old_sigpipe; | |
146 | ||
147 | /* Sanity checks */ | |
148 | if (socket_path == NULL && tcp_port == 0) | |
149 | fatal("You must specify a port or a socket"); | |
150 | if (socket_path != NULL && | |
151 | strlen(socket_path) >= sizeof(addr_un->sun_path)) | |
152 | fatal("Random pool path is too long"); | |
153 | if (len <= 0 || len > 255) | |
154 | fatal("Too many bytes (%d) to read from PRNGD", len); | |
155 | ||
156 | memset(&addr, '\0', sizeof(addr)); | |
157 | ||
158 | if (tcp_port != 0) { | |
159 | addr_in->sin_family = AF_INET; | |
160 | addr_in->sin_addr.s_addr = htonl(INADDR_LOOPBACK); | |
161 | addr_in->sin_port = htons(tcp_port); | |
162 | addr_len = sizeof(*addr_in); | |
163 | } else { | |
164 | addr_un->sun_family = AF_UNIX; | |
165 | strlcpy(addr_un->sun_path, socket_path, | |
166 | sizeof(addr_un->sun_path)); | |
167 | addr_len = offsetof(struct sockaddr_un, sun_path) + | |
168 | strlen(socket_path) + 1; | |
169 | } | |
170 | ||
171 | old_sigpipe = mysignal(SIGPIPE, SIG_IGN); | |
172 | ||
173 | errors = 0; | |
174 | rval = -1; | |
175 | reopen: | |
176 | fd = socket(addr.ss_family, SOCK_STREAM, 0); | |
177 | if (fd == -1) { | |
178 | error("Couldn't create socket: %s", strerror(errno)); | |
179 | goto done; | |
180 | } | |
181 | ||
182 | if (connect(fd, (struct sockaddr*)&addr, addr_len) == -1) { | |
183 | if (tcp_port != 0) { | |
184 | error("Couldn't connect to PRNGD port %d: %s", | |
185 | tcp_port, strerror(errno)); | |
186 | } else { | |
187 | error("Couldn't connect to PRNGD socket \"%s\": %s", | |
188 | addr_un->sun_path, strerror(errno)); | |
189 | } | |
190 | goto done; | |
191 | } | |
192 | ||
193 | /* Send blocking read request to PRNGD */ | |
194 | msg[0] = 0x02; | |
195 | msg[1] = len; | |
196 | ||
197 | if (atomicio(vwrite, fd, msg, sizeof(msg)) != sizeof(msg)) { | |
198 | if (errno == EPIPE && errors < 10) { | |
199 | close(fd); | |
200 | errors++; | |
201 | goto reopen; | |
202 | } | |
203 | error("Couldn't write to PRNGD socket: %s", | |
204 | strerror(errno)); | |
205 | goto done; | |
206 | } | |
207 | ||
208 | if (atomicio(read, fd, buf, len) != (size_t)len) { | |
209 | if (errno == EPIPE && errors < 10) { | |
210 | close(fd); | |
211 | errors++; | |
212 | goto reopen; | |
213 | } | |
214 | error("Couldn't read from PRNGD socket: %s", | |
215 | strerror(errno)); | |
216 | goto done; | |
217 | } | |
218 | ||
219 | rval = 0; | |
220 | done: | |
221 | mysignal(SIGPIPE, old_sigpipe); | |
222 | if (fd != -1) | |
223 | close(fd); | |
224 | return rval; | |
225 | } | |
226 | ||
227 | static int | |
228 | seed_from_prngd(unsigned char *buf, size_t bytes) | |
229 | { | |
230 | #ifdef PRNGD_PORT | |
231 | debug("trying egd/prngd port %d", PRNGD_PORT); | |
232 | if (get_random_bytes_prngd(buf, bytes, PRNGD_PORT, NULL) == 0) | |
233 | return 0; | |
234 | #endif | |
235 | #ifdef PRNGD_SOCKET | |
236 | debug("trying egd/prngd socket %s", PRNGD_SOCKET); | |
237 | if (get_random_bytes_prngd(buf, bytes, 0, PRNGD_SOCKET) == 0) | |
238 | return 0; | |
239 | #endif | |
240 | return -1; | |
241 | } | |
242 | ||
243 | double | |
244 | stir_gettimeofday(double entropy_estimate) | |
245 | { | |
246 | struct timeval tv; | |
247 | ||
248 | if (gettimeofday(&tv, NULL) == -1) | |
249 | fatal("Couldn't gettimeofday: %s", strerror(errno)); | |
250 | ||
251 | RAND_add(&tv, sizeof(tv), entropy_estimate); | |
252 | ||
253 | return entropy_estimate; | |
254 | } | |
255 | ||
256 | double | |
257 | stir_clock(double entropy_estimate) | |
258 | { | |
259 | #ifdef HAVE_CLOCK | |
260 | clock_t c; | |
261 | ||
262 | c = clock(); | |
263 | RAND_add(&c, sizeof(c), entropy_estimate); | |
264 | ||
265 | return entropy_estimate; | |
266 | #else /* _HAVE_CLOCK */ | |
267 | return 0; | |
268 | #endif /* _HAVE_CLOCK */ | |
269 | } | |
270 | ||
271 | double | |
272 | stir_rusage(int who, double entropy_estimate) | |
273 | { | |
274 | #ifdef HAVE_GETRUSAGE | |
275 | struct rusage ru; | |
276 | ||
277 | if (getrusage(who, &ru) == -1) | |
278 | return 0; | |
279 | ||
280 | RAND_add(&ru, sizeof(ru), entropy_estimate); | |
281 | ||
282 | return entropy_estimate; | |
283 | #else /* _HAVE_GETRUSAGE */ | |
284 | return 0; | |
285 | #endif /* _HAVE_GETRUSAGE */ | |
286 | } | |
287 | ||
288 | static int | |
289 | timeval_diff(struct timeval *t1, struct timeval *t2) | |
290 | { | |
291 | int secdiff, usecdiff; | |
292 | ||
293 | secdiff = t2->tv_sec - t1->tv_sec; | |
294 | usecdiff = (secdiff*1000000) + (t2->tv_usec - t1->tv_usec); | |
295 | return (int)(usecdiff / 1000); | |
296 | } | |
297 | ||
298 | double | |
299 | hash_command_output(entropy_cmd_t *src, unsigned char *hash) | |
300 | { | |
301 | char buf[8192]; | |
302 | fd_set rdset; | |
303 | int bytes_read, cmd_eof, error_abort, msec_elapsed, p[2]; | |
304 | int status, total_bytes_read; | |
305 | static int devnull = -1; | |
306 | pid_t pid; | |
307 | SHA_CTX sha; | |
308 | struct timeval tv_start, tv_current; | |
309 | ||
310 | debug3("Reading output from \'%s\'", src->cmdstring); | |
311 | ||
312 | if (devnull == -1) { | |
313 | devnull = open("/dev/null", O_RDWR); | |
314 | if (devnull == -1) | |
315 | fatal("Couldn't open /dev/null: %s", | |
316 | strerror(errno)); | |
317 | } | |
318 | ||
319 | if (pipe(p) == -1) | |
320 | fatal("Couldn't open pipe: %s", strerror(errno)); | |
321 | ||
322 | (void)gettimeofday(&tv_start, NULL); /* record start time */ | |
323 | ||
324 | switch (pid = fork()) { | |
325 | case -1: /* Error */ | |
326 | close(p[0]); | |
327 | close(p[1]); | |
328 | fatal("Couldn't fork: %s", strerror(errno)); | |
329 | /* NOTREACHED */ | |
330 | case 0: /* Child */ | |
331 | dup2(devnull, STDIN_FILENO); | |
332 | dup2(p[1], STDOUT_FILENO); | |
333 | dup2(p[1], STDERR_FILENO); | |
334 | close(p[0]); | |
335 | close(p[1]); | |
336 | close(devnull); | |
337 | ||
338 | execv(src->path, (char**)(src->args)); | |
339 | ||
340 | debug("(child) Couldn't exec '%s': %s", | |
341 | src->cmdstring, strerror(errno)); | |
342 | _exit(-1); | |
343 | default: /* Parent */ | |
344 | break; | |
345 | } | |
346 | ||
347 | RAND_add(&pid, sizeof(&pid), 0.0); | |
348 | ||
349 | close(p[1]); | |
350 | ||
351 | /* Hash output from child */ | |
352 | SHA1_Init(&sha); | |
353 | ||
354 | cmd_eof = error_abort = msec_elapsed = total_bytes_read = 0; | |
355 | while (!error_abort && !cmd_eof) { | |
356 | int ret; | |
357 | struct timeval tv; | |
358 | int msec_remaining; | |
359 | ||
360 | (void) gettimeofday(&tv_current, 0); | |
361 | msec_elapsed = timeval_diff(&tv_start, &tv_current); | |
362 | if (msec_elapsed >= entropy_timeout_current) { | |
363 | error_abort=1; | |
364 | continue; | |
365 | } | |
366 | msec_remaining = entropy_timeout_current - msec_elapsed; | |
367 | ||
368 | FD_ZERO(&rdset); | |
369 | FD_SET(p[0], &rdset); | |
370 | tv.tv_sec = msec_remaining / 1000; | |
371 | tv.tv_usec = (msec_remaining % 1000) * 1000; | |
372 | ||
373 | ret = select(p[0] + 1, &rdset, NULL, NULL, &tv); | |
374 | ||
375 | RAND_add(&tv, sizeof(tv), 0.0); | |
376 | ||
377 | switch (ret) { | |
378 | case 0: | |
379 | /* timer expired */ | |
380 | error_abort = 1; | |
381 | kill(pid, SIGINT); | |
382 | break; | |
383 | case 1: | |
384 | /* command input */ | |
385 | do { | |
386 | bytes_read = read(p[0], buf, sizeof(buf)); | |
387 | } while (bytes_read == -1 && errno == EINTR); | |
388 | RAND_add(&bytes_read, sizeof(&bytes_read), 0.0); | |
389 | if (bytes_read == -1) { | |
390 | error_abort = 1; | |
391 | break; | |
392 | } else if (bytes_read) { | |
393 | SHA1_Update(&sha, buf, bytes_read); | |
394 | total_bytes_read += bytes_read; | |
395 | } else { | |
396 | cmd_eof = 1; | |
397 | } | |
398 | break; | |
399 | case -1: | |
400 | default: | |
401 | /* error */ | |
402 | debug("Command '%s': select() failed: %s", | |
403 | src->cmdstring, strerror(errno)); | |
404 | error_abort = 1; | |
405 | break; | |
406 | } | |
407 | } | |
408 | ||
409 | SHA1_Final(hash, &sha); | |
410 | ||
411 | close(p[0]); | |
412 | ||
413 | debug3("Time elapsed: %d msec", msec_elapsed); | |
414 | ||
415 | if (waitpid(pid, &status, 0) == -1) { | |
416 | error("Couldn't wait for child '%s' completion: %s", | |
417 | src->cmdstring, strerror(errno)); | |
418 | return 0.0; | |
419 | } | |
420 | ||
421 | RAND_add(&status, sizeof(&status), 0.0); | |
422 | ||
423 | if (error_abort) { | |
424 | /* | |
425 | * Closing p[0] on timeout causes the entropy command to | |
426 | * SIGPIPE. Take whatever output we got, and mark this | |
427 | * command as slow | |
428 | */ | |
429 | debug2("Command '%s' timed out", src->cmdstring); | |
430 | src->sticky_badness *= 2; | |
431 | src->badness = src->sticky_badness; | |
432 | return total_bytes_read; | |
433 | } | |
434 | ||
435 | if (WIFEXITED(status)) { | |
436 | if (WEXITSTATUS(status) == 0) { | |
437 | return total_bytes_read; | |
438 | } else { | |
439 | debug2("Command '%s' exit status was %d", | |
440 | src->cmdstring, WEXITSTATUS(status)); | |
441 | src->badness = src->sticky_badness = 128; | |
442 | return 0.0; | |
443 | } | |
444 | } else if (WIFSIGNALED(status)) { | |
445 | debug2("Command '%s' returned on uncaught signal %d !", | |
446 | src->cmdstring, status); | |
447 | src->badness = src->sticky_badness = 128; | |
448 | return 0.0; | |
449 | } else | |
450 | return 0.0; | |
451 | } | |
452 | ||
453 | double | |
454 | stir_from_system(void) | |
455 | { | |
456 | double total_entropy_estimate; | |
457 | long int i; | |
458 | ||
459 | total_entropy_estimate = 0; | |
460 | ||
461 | i = getpid(); | |
462 | RAND_add(&i, sizeof(i), 0.5); | |
463 | total_entropy_estimate += 0.1; | |
464 | ||
465 | i = getppid(); | |
466 | RAND_add(&i, sizeof(i), 0.5); | |
467 | total_entropy_estimate += 0.1; | |
468 | ||
469 | i = getuid(); | |
470 | RAND_add(&i, sizeof(i), 0.0); | |
471 | i = getgid(); | |
472 | RAND_add(&i, sizeof(i), 0.0); | |
473 | ||
474 | total_entropy_estimate += stir_gettimeofday(1.0); | |
475 | total_entropy_estimate += stir_clock(0.5); | |
476 | total_entropy_estimate += stir_rusage(RUSAGE_SELF, 2.0); | |
477 | ||
478 | return total_entropy_estimate; | |
479 | } | |
480 | ||
481 | double | |
482 | stir_from_programs(void) | |
483 | { | |
484 | int c; | |
485 | double entropy, total_entropy; | |
486 | unsigned char hash[SHA_DIGEST_LENGTH]; | |
487 | ||
488 | total_entropy = 0; | |
489 | for(c = 0; entropy_cmds[c].path != NULL; c++) { | |
490 | if (!entropy_cmds[c].badness) { | |
491 | /* Hash output from command */ | |
492 | entropy = hash_command_output(&entropy_cmds[c], | |
493 | hash); | |
494 | ||
495 | /* Scale back estimate by command's rate */ | |
496 | entropy *= entropy_cmds[c].rate; | |
497 | ||
498 | /* Upper bound of entropy is SHA_DIGEST_LENGTH */ | |
499 | if (entropy > SHA_DIGEST_LENGTH) | |
500 | entropy = SHA_DIGEST_LENGTH; | |
501 | ||
502 | /* Stir it in */ | |
503 | RAND_add(hash, sizeof(hash), entropy); | |
504 | ||
505 | debug3("Got %0.2f bytes of entropy from '%s'", | |
506 | entropy, entropy_cmds[c].cmdstring); | |
507 | ||
508 | total_entropy += entropy; | |
509 | ||
510 | /* Execution time should be a bit unpredictable */ | |
511 | total_entropy += stir_gettimeofday(0.05); | |
512 | total_entropy += stir_clock(0.05); | |
513 | total_entropy += stir_rusage(RUSAGE_SELF, 0.1); | |
514 | total_entropy += stir_rusage(RUSAGE_CHILDREN, 0.1); | |
515 | } else { | |
516 | debug2("Command '%s' disabled (badness %d)", | |
517 | entropy_cmds[c].cmdstring, | |
518 | entropy_cmds[c].badness); | |
519 | ||
520 | if (entropy_cmds[c].badness > 0) | |
521 | entropy_cmds[c].badness--; | |
522 | } | |
523 | } | |
524 | ||
525 | return total_entropy; | |
526 | } | |
527 | ||
528 | /* | |
529 | * prng seedfile functions | |
530 | */ | |
531 | int | |
532 | prng_check_seedfile(char *filename) | |
533 | { | |
534 | struct stat st; | |
535 | ||
536 | /* | |
537 | * XXX raceable: eg replace seed between this stat and subsequent | |
538 | * open. Not such a problem because we don't really trust the | |
539 | * seed file anyway. | |
540 | * XXX: use secure path checking as elsewhere in OpenSSH | |
541 | */ | |
542 | if (lstat(filename, &st) == -1) { | |
543 | /* Give up on hard errors */ | |
544 | if (errno != ENOENT) | |
545 | debug("WARNING: Couldn't stat random seed file " | |
546 | "\"%.100s\": %s", filename, strerror(errno)); | |
547 | return 0; | |
548 | } | |
549 | ||
550 | /* regular file? */ | |
551 | if (!S_ISREG(st.st_mode)) | |
552 | fatal("PRNG seedfile %.100s is not a regular file", | |
553 | filename); | |
554 | ||
555 | /* mode 0600, owned by root or the current user? */ | |
556 | if (((st.st_mode & 0177) != 0) || !(st.st_uid == getuid())) { | |
557 | debug("WARNING: PRNG seedfile %.100s must be mode 0600, " | |
558 | "owned by uid %li", filename, (long int)getuid()); | |
559 | return 0; | |
560 | } | |
561 | ||
562 | return 1; | |
563 | } | |
564 | ||
565 | void | |
566 | prng_write_seedfile(void) | |
567 | { | |
568 | int fd, save_errno; | |
569 | unsigned char seed[SEED_FILE_SIZE]; | |
570 | char filename[MAXPATHLEN], tmpseed[MAXPATHLEN]; | |
571 | struct passwd *pw; | |
572 | mode_t old_umask; | |
573 | ||
574 | pw = getpwuid(getuid()); | |
575 | if (pw == NULL) | |
576 | fatal("Couldn't get password entry for current user " | |
577 | "(%li): %s", (long int)getuid(), 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 | if (mkdir(filename, 0700) < 0 && errno != EEXIST) | |
583 | fatal("mkdir %.200s: %s", filename, strerror(errno)); | |
584 | ||
585 | snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir, | |
586 | SSH_PRNG_SEED_FILE); | |
587 | ||
588 | strlcpy(tmpseed, filename, sizeof(tmpseed)); | |
589 | if (strlcat(tmpseed, ".XXXXXXXXXX", sizeof(tmpseed)) >= | |
590 | sizeof(tmpseed)) | |
591 | fatal("PRNG seed filename too long"); | |
592 | ||
593 | if (RAND_bytes(seed, sizeof(seed)) <= 0) | |
594 | fatal("PRNG seed extraction failed"); | |
595 | ||
596 | /* Don't care if the seed doesn't exist */ | |
597 | prng_check_seedfile(filename); | |
598 | ||
599 | old_umask = umask(0177); | |
600 | ||
601 | if ((fd = mkstemp(tmpseed)) == -1) { | |
602 | debug("WARNING: couldn't make temporary PRNG seedfile %.100s " | |
603 | "(%.100s)", tmpseed, strerror(errno)); | |
604 | } else { | |
605 | debug("writing PRNG seed to file %.100s", tmpseed); | |
606 | if (atomicio(vwrite, fd, &seed, sizeof(seed)) < sizeof(seed)) { | |
607 | save_errno = errno; | |
608 | close(fd); | |
609 | unlink(tmpseed); | |
610 | fatal("problem writing PRNG seedfile %.100s " | |
611 | "(%.100s)", filename, strerror(save_errno)); | |
612 | } | |
613 | close(fd); | |
614 | debug("moving temporary PRNG seed to file %.100s", filename); | |
615 | if (rename(tmpseed, filename) == -1) { | |
616 | save_errno = errno; | |
617 | unlink(tmpseed); | |
618 | fatal("problem renaming PRNG seedfile from %.100s " | |
619 | "to %.100s (%.100s)", tmpseed, filename, | |
620 | strerror(save_errno)); | |
621 | } | |
622 | } | |
623 | umask(old_umask); | |
624 | } | |
625 | ||
626 | void | |
627 | prng_read_seedfile(void) | |
628 | { | |
629 | int fd; | |
630 | char seed[SEED_FILE_SIZE], filename[MAXPATHLEN]; | |
631 | struct passwd *pw; | |
632 | ||
633 | pw = getpwuid(getuid()); | |
634 | if (pw == NULL) | |
635 | fatal("Couldn't get password entry for current user " | |
636 | "(%li): %s", (long int)getuid(), strerror(errno)); | |
637 | ||
638 | snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir, | |
639 | SSH_PRNG_SEED_FILE); | |
640 | ||
641 | debug("loading PRNG seed from file %.100s", filename); | |
642 | ||
643 | if (!prng_check_seedfile(filename)) { | |
644 | verbose("Random seed file not found or invalid, ignoring."); | |
645 | return; | |
646 | } | |
647 | ||
648 | /* open the file and read in the seed */ | |
649 | fd = open(filename, O_RDONLY); | |
650 | if (fd == -1) | |
651 | fatal("could not open PRNG seedfile %.100s (%.100s)", | |
652 | filename, strerror(errno)); | |
653 | ||
654 | if (atomicio(read, fd, &seed, sizeof(seed)) < sizeof(seed)) { | |
655 | verbose("invalid or short read from PRNG seedfile " | |
656 | "%.100s - ignoring", filename); | |
657 | memset(seed, '\0', sizeof(seed)); | |
658 | } | |
659 | close(fd); | |
660 | ||
661 | /* stir in the seed, with estimated entropy zero */ | |
662 | RAND_add(&seed, sizeof(seed), 0.0); | |
663 | } | |
664 | ||
665 | ||
666 | /* | |
667 | * entropy command initialisation functions | |
668 | */ | |
669 | int | |
670 | prng_read_commands(char *cmdfilename) | |
671 | { | |
672 | char cmd[SEED_FILE_SIZE], *cp, line[1024], path[SEED_FILE_SIZE]; | |
673 | double est; | |
674 | entropy_cmd_t *entcmd; | |
675 | FILE *f; | |
676 | int cur_cmd, linenum, num_cmds, arg; | |
677 | ||
678 | if ((f = fopen(cmdfilename, "r")) == NULL) { | |
679 | fatal("couldn't read entropy commands file %.100s: %.100s", | |
680 | cmdfilename, strerror(errno)); | |
681 | } | |
682 | ||
683 | num_cmds = 64; | |
684 | entcmd = xcalloc(num_cmds, sizeof(entropy_cmd_t)); | |
685 | ||
686 | /* Read in file */ | |
687 | cur_cmd = linenum = 0; | |
688 | while (fgets(line, sizeof(line), f)) { | |
689 | linenum++; | |
690 | ||
691 | /* Skip leading whitespace, blank lines and comments */ | |
692 | cp = line + strspn(line, WHITESPACE); | |
693 | if ((*cp == 0) || (*cp == '#')) | |
694 | continue; /* done with this line */ | |
695 | ||
696 | /* | |
697 | * The first non-whitespace char should be a double quote | |
698 | * delimiting the commandline | |
699 | */ | |
700 | if (*cp != '"') { | |
701 | error("bad entropy command, %.100s line %d", | |
702 | cmdfilename, linenum); | |
703 | continue; | |
704 | } | |
705 | ||
706 | /* | |
707 | * First token, command args (incl. argv[0]) in double | |
708 | * quotes | |
709 | */ | |
710 | cp = strtok(cp, "\""); | |
711 | if (cp == NULL) { | |
712 | error("missing or bad command string, %.100s " | |
713 | "line %d -- ignored", cmdfilename, linenum); | |
714 | continue; | |
715 | } | |
716 | strlcpy(cmd, cp, sizeof(cmd)); | |
717 | ||
718 | /* Second token, full command path */ | |
719 | if ((cp = strtok(NULL, WHITESPACE)) == NULL) { | |
720 | error("missing command path, %.100s " | |
721 | "line %d -- ignored", cmdfilename, linenum); | |
722 | continue; | |
723 | } | |
724 | ||
725 | /* Did configure mark this as dead? */ | |
726 | if (strncmp("undef", cp, 5) == 0) | |
727 | continue; | |
728 | ||
729 | strlcpy(path, cp, sizeof(path)); | |
730 | ||
731 | /* Third token, entropy rate estimate for this command */ | |
732 | if ((cp = strtok(NULL, WHITESPACE)) == NULL) { | |
733 | error("missing entropy estimate, %.100s " | |
734 | "line %d -- ignored", cmdfilename, linenum); | |
735 | continue; | |
736 | } | |
737 | est = strtod(cp, NULL); | |
738 | ||
739 | /* end of line */ | |
740 | if ((cp = strtok(NULL, WHITESPACE)) != NULL) { | |
741 | error("garbage at end of line %d in %.100s " | |
742 | "-- ignored", linenum, cmdfilename); | |
743 | continue; | |
744 | } | |
745 | ||
746 | /* save the command for debug messages */ | |
747 | entcmd[cur_cmd].cmdstring = xstrdup(cmd); | |
748 | ||
749 | /* split the command args */ | |
750 | cp = strtok(cmd, WHITESPACE); | |
751 | arg = 0; | |
752 | do { | |
753 | entcmd[cur_cmd].args[arg] = xstrdup(cp); | |
754 | arg++; | |
755 | } while(arg < NUM_ARGS && (cp = strtok(NULL, WHITESPACE))); | |
756 | ||
757 | if (strtok(NULL, WHITESPACE)) | |
758 | error("ignored extra commands (max %d), %.100s " | |
759 | "line %d", NUM_ARGS, cmdfilename, linenum); | |
760 | ||
761 | /* Copy the command path and rate estimate */ | |
762 | entcmd[cur_cmd].path = xstrdup(path); | |
763 | entcmd[cur_cmd].rate = est; | |
764 | ||
765 | /* Initialise other values */ | |
766 | entcmd[cur_cmd].sticky_badness = 1; | |
767 | ||
768 | cur_cmd++; | |
769 | ||
770 | /* | |
771 | * If we've filled the array, reallocate it twice the size | |
772 | * Do this now because even if this we're on the last | |
773 | * command we need another slot to mark the last entry | |
774 | */ | |
775 | if (cur_cmd == num_cmds) { | |
776 | num_cmds *= 2; | |
777 | entcmd = xrealloc(entcmd, num_cmds, | |
778 | sizeof(entropy_cmd_t)); | |
779 | } | |
780 | } | |
781 | ||
782 | /* zero the last entry */ | |
783 | memset(&entcmd[cur_cmd], '\0', sizeof(entropy_cmd_t)); | |
784 | ||
785 | /* trim to size */ | |
786 | entropy_cmds = xrealloc(entcmd, (cur_cmd + 1), | |
787 | sizeof(entropy_cmd_t)); | |
788 | ||
789 | debug("Loaded %d entropy commands from %.100s", cur_cmd, | |
790 | cmdfilename); | |
791 | ||
792 | fclose(f); | |
793 | return cur_cmd < MIN_ENTROPY_SOURCES ? -1 : 0; | |
794 | } | |
795 | ||
796 | void | |
797 | usage(void) | |
798 | { | |
799 | fprintf(stderr, "Usage: %s [options]\n", __progname); | |
800 | fprintf(stderr, " -v Verbose; display verbose debugging messages.\n"); | |
801 | fprintf(stderr, " Multiple -v increases verbosity.\n"); | |
802 | fprintf(stderr, " -x Force output in hexadecimal (for debugging)\n"); | |
803 | fprintf(stderr, " -X Force output in binary\n"); | |
804 | fprintf(stderr, " -b bytes Number of bytes to output (default %d)\n", | |
805 | OUTPUT_SEED_SIZE); | |
806 | } | |
807 | ||
808 | int | |
809 | main(int argc, char **argv) | |
810 | { | |
811 | unsigned char *buf; | |
812 | int ret, ch, debug_level, output_hex, bytes; | |
813 | extern char *optarg; | |
814 | LogLevel ll; | |
815 | ||
816 | __progname = ssh_get_progname(argv[0]); | |
817 | log_init(argv[0], SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_USER, 1); | |
818 | ||
819 | ll = SYSLOG_LEVEL_INFO; | |
820 | debug_level = output_hex = 0; | |
821 | bytes = OUTPUT_SEED_SIZE; | |
822 | ||
823 | /* Don't write binary data to a tty, unless we are forced to */ | |
824 | if (isatty(STDOUT_FILENO)) | |
825 | output_hex = 1; | |
826 | ||
827 | while ((ch = getopt(argc, argv, "vxXhb:")) != -1) { | |
828 | switch (ch) { | |
829 | case 'v': | |
830 | if (debug_level < 3) | |
831 | ll = SYSLOG_LEVEL_DEBUG1 + debug_level++; | |
832 | break; | |
833 | case 'x': | |
834 | output_hex = 1; | |
835 | break; | |
836 | case 'X': | |
837 | output_hex = 0; | |
838 | break; | |
839 | case 'b': | |
840 | if ((bytes = atoi(optarg)) <= 0) | |
841 | fatal("Invalid number of output bytes"); | |
842 | break; | |
843 | case 'h': | |
844 | usage(); | |
845 | exit(0); | |
846 | default: | |
847 | error("Invalid commandline option"); | |
848 | usage(); | |
849 | } | |
850 | } | |
851 | ||
852 | log_init(argv[0], ll, SYSLOG_FACILITY_USER, 1); | |
853 | ||
854 | #ifdef USE_SEED_FILES | |
855 | prng_read_seedfile(); | |
856 | #endif | |
857 | ||
858 | buf = xmalloc(bytes); | |
859 | ||
860 | /* | |
861 | * Seed the RNG from wherever we can | |
862 | */ | |
863 | ||
864 | /* Take whatever is on the stack, but don't credit it */ | |
865 | RAND_add(buf, bytes, 0); | |
866 | ||
867 | debug("Seeded RNG with %i bytes from system calls", | |
868 | (int)stir_from_system()); | |
869 | ||
870 | /* try prngd, fall back to commands if prngd fails or not configured */ | |
871 | if (seed_from_prngd(buf, bytes) == 0) { | |
872 | RAND_add(buf, bytes, bytes); | |
873 | } else { | |
874 | /* Read in collection commands */ | |
875 | if (prng_read_commands(SSH_PRNG_COMMAND_FILE) == -1) | |
876 | fatal("PRNG initialisation failed -- exiting."); | |
877 | debug("Seeded RNG with %i bytes from programs", | |
878 | (int)stir_from_programs()); | |
879 | } | |
880 | ||
881 | #ifdef USE_SEED_FILES | |
882 | prng_write_seedfile(); | |
883 | #endif | |
884 | ||
885 | /* | |
886 | * Write the seed to stdout | |
887 | */ | |
888 | ||
889 | if (!RAND_status()) | |
890 | fatal("Not enough entropy in RNG"); | |
891 | ||
892 | if (RAND_bytes(buf, bytes) <= 0) | |
893 | fatal("Couldn't extract entropy from PRNG"); | |
894 | ||
895 | if (output_hex) { | |
896 | for(ret = 0; ret < bytes; ret++) | |
897 | printf("%02x", (unsigned char)(buf[ret])); | |
898 | printf("\n"); | |
899 | } else | |
900 | ret = atomicio(vwrite, STDOUT_FILENO, buf, bytes); | |
901 | ||
902 | memset(buf, '\0', bytes); | |
903 | xfree(buf); | |
904 | ||
905 | return ret == bytes ? 0 : 1; | |
906 | } | |
907 | ||
908 | /* | |
909 | * We may attempt to re-seed during mkstemp if we are using the one in the | |
910 | * compat library (via mkstemp -> _gettemp -> arc4random -> seed_rng) so we | |
911 | * need our own seed_rng(). We must also check that we have enough entropy. | |
912 | */ | |
913 | void | |
914 | seed_rng(void) | |
915 | { | |
916 | if (!RAND_status()) | |
917 | fatal("Not enough entropy in RNG"); | |
918 | } |