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d832c38e | 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 | ||
30460aeb | 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 <stdarg.h> | |
34 | #include <stddef.h> | |
35 | ||
36 | #include <netinet/in.h> | |
37 | #include <arpa/inet.h> | |
38 | ||
39 | #ifdef HAVE_SYS_UN_H | |
40 | # include <sys/un.h> | |
41 | #endif | |
42 | ||
43 | #include <errno.h> | |
44 | #include <fcntl.h> | |
45 | #include <pwd.h> | |
46 | #include <signal.h> | |
47 | #include <time.h> | |
48 | #include <unistd.h> | |
49 | ||
d832c38e | 50 | #include <openssl/rand.h> |
51 | #include <openssl/sha.h> | |
52 | #include <openssl/crypto.h> | |
53 | ||
54 | /* SunOS 4.4.4 needs this */ | |
55 | #ifdef HAVE_FLOATINGPOINT_H | |
56 | # include <floatingpoint.h> | |
57 | #endif /* HAVE_FLOATINGPOINT_H */ | |
58 | ||
59 | #include "misc.h" | |
60 | #include "xmalloc.h" | |
61 | #include "atomicio.h" | |
62 | #include "pathnames.h" | |
63 | #include "log.h" | |
64 | ||
d832c38e | 65 | /* Number of bytes we write out */ |
66 | #define OUTPUT_SEED_SIZE 48 | |
67 | ||
68 | /* Length of on-disk seedfiles */ | |
69 | #define SEED_FILE_SIZE 1024 | |
70 | ||
71 | /* Maximum number of command-line arguments to read from file */ | |
72 | #define NUM_ARGS 10 | |
73 | ||
74 | /* Minimum number of usable commands to be considered sufficient */ | |
75 | #define MIN_ENTROPY_SOURCES 16 | |
76 | ||
77 | /* Path to on-disk seed file (relative to user's home directory */ | |
78 | #ifndef SSH_PRNG_SEED_FILE | |
79 | # define SSH_PRNG_SEED_FILE _PATH_SSH_USER_DIR"/prng_seed" | |
80 | #endif | |
81 | ||
82 | /* Path to PRNG commands list */ | |
83 | #ifndef SSH_PRNG_COMMAND_FILE | |
84 | # define SSH_PRNG_COMMAND_FILE SSHDIR "/ssh_prng_cmds" | |
85 | #endif | |
86 | ||
d832c38e | 87 | extern char *__progname; |
d832c38e | 88 | |
89 | #define WHITESPACE " \t\n" | |
90 | ||
91 | #ifndef RUSAGE_SELF | |
92 | # define RUSAGE_SELF 0 | |
93 | #endif | |
94 | #ifndef RUSAGE_CHILDREN | |
95 | # define RUSAGE_CHILDREN 0 | |
96 | #endif | |
97 | ||
98 | #if !defined(PRNGD_SOCKET) && !defined(PRNGD_PORT) | |
99 | # define USE_SEED_FILES | |
100 | #endif | |
101 | ||
102 | typedef struct { | |
103 | /* Proportion of data that is entropy */ | |
104 | double rate; | |
105 | /* Counter goes positive if this command times out */ | |
106 | unsigned int badness; | |
107 | /* Increases by factor of two each timeout */ | |
108 | unsigned int sticky_badness; | |
109 | /* Path to executable */ | |
110 | char *path; | |
111 | /* argv to pass to executable */ | |
112 | char *args[NUM_ARGS]; /* XXX: arbitrary limit */ | |
113 | /* full command string (debug) */ | |
114 | char *cmdstring; | |
115 | } entropy_cmd_t; | |
116 | ||
117 | /* slow command timeouts (all in milliseconds) */ | |
118 | /* static int entropy_timeout_default = ENTROPY_TIMEOUT_MSEC; */ | |
119 | static int entropy_timeout_current = ENTROPY_TIMEOUT_MSEC; | |
120 | ||
121 | /* this is initialised from a file, by prng_read_commands() */ | |
122 | static entropy_cmd_t *entropy_cmds = NULL; | |
123 | ||
124 | /* Prototypes */ | |
125 | double stir_from_system(void); | |
126 | double stir_from_programs(void); | |
127 | double stir_gettimeofday(double entropy_estimate); | |
128 | double stir_clock(double entropy_estimate); | |
129 | double stir_rusage(int who, double entropy_estimate); | |
d03f4262 | 130 | double hash_command_output(entropy_cmd_t *src, unsigned char *hash); |
540d72c3 | 131 | int get_random_bytes_prngd(unsigned char *buf, int len, |
d832c38e | 132 | unsigned short tcp_port, char *socket_path); |
133 | ||
134 | /* | |
135 | * Collect 'len' bytes of entropy into 'buf' from PRNGD/EGD daemon | |
136 | * listening either on 'tcp_port', or via Unix domain socket at * | |
137 | * 'socket_path'. | |
540d72c3 | 138 | * Either a non-zero tcp_port or a non-null socket_path must be |
d832c38e | 139 | * supplied. |
140 | * Returns 0 on success, -1 on error | |
141 | */ | |
142 | int | |
540d72c3 | 143 | get_random_bytes_prngd(unsigned char *buf, int len, |
d832c38e | 144 | unsigned short tcp_port, char *socket_path) |
145 | { | |
146 | int fd, addr_len, rval, errors; | |
2ce0bfe4 | 147 | u_char msg[2]; |
d832c38e | 148 | struct sockaddr_storage addr; |
149 | struct sockaddr_in *addr_in = (struct sockaddr_in *)&addr; | |
150 | struct sockaddr_un *addr_un = (struct sockaddr_un *)&addr; | |
151 | mysig_t old_sigpipe; | |
152 | ||
153 | /* Sanity checks */ | |
154 | if (socket_path == NULL && tcp_port == 0) | |
155 | fatal("You must specify a port or a socket"); | |
156 | if (socket_path != NULL && | |
157 | strlen(socket_path) >= sizeof(addr_un->sun_path)) | |
158 | fatal("Random pool path is too long"); | |
2ce0bfe4 | 159 | if (len <= 0 || len > 255) |
160 | fatal("Too many bytes (%d) to read from PRNGD", len); | |
d832c38e | 161 | |
162 | memset(&addr, '\0', sizeof(addr)); | |
163 | ||
164 | if (tcp_port != 0) { | |
165 | addr_in->sin_family = AF_INET; | |
166 | addr_in->sin_addr.s_addr = htonl(INADDR_LOOPBACK); | |
167 | addr_in->sin_port = htons(tcp_port); | |
168 | addr_len = sizeof(*addr_in); | |
169 | } else { | |
170 | addr_un->sun_family = AF_UNIX; | |
171 | strlcpy(addr_un->sun_path, socket_path, | |
172 | sizeof(addr_un->sun_path)); | |
173 | addr_len = offsetof(struct sockaddr_un, sun_path) + | |
174 | strlen(socket_path) + 1; | |
175 | } | |
176 | ||
177 | old_sigpipe = mysignal(SIGPIPE, SIG_IGN); | |
178 | ||
179 | errors = 0; | |
180 | rval = -1; | |
181 | reopen: | |
182 | fd = socket(addr.ss_family, SOCK_STREAM, 0); | |
183 | if (fd == -1) { | |
184 | error("Couldn't create socket: %s", strerror(errno)); | |
185 | goto done; | |
186 | } | |
187 | ||
188 | if (connect(fd, (struct sockaddr*)&addr, addr_len) == -1) { | |
189 | if (tcp_port != 0) { | |
190 | error("Couldn't connect to PRNGD port %d: %s", | |
191 | tcp_port, strerror(errno)); | |
192 | } else { | |
193 | error("Couldn't connect to PRNGD socket \"%s\": %s", | |
194 | addr_un->sun_path, strerror(errno)); | |
195 | } | |
196 | goto done; | |
197 | } | |
198 | ||
199 | /* Send blocking read request to PRNGD */ | |
200 | msg[0] = 0x02; | |
201 | msg[1] = len; | |
202 | ||
7cac2b65 | 203 | if (atomicio(vwrite, fd, msg, sizeof(msg)) != sizeof(msg)) { |
d832c38e | 204 | if (errno == EPIPE && errors < 10) { |
205 | close(fd); | |
206 | errors++; | |
207 | goto reopen; | |
208 | } | |
209 | error("Couldn't write to PRNGD socket: %s", | |
210 | strerror(errno)); | |
211 | goto done; | |
212 | } | |
213 | ||
2ce0bfe4 | 214 | if (atomicio(read, fd, buf, len) != (size_t)len) { |
d832c38e | 215 | if (errno == EPIPE && errors < 10) { |
216 | close(fd); | |
217 | errors++; | |
218 | goto reopen; | |
219 | } | |
220 | error("Couldn't read from PRNGD socket: %s", | |
221 | strerror(errno)); | |
222 | goto done; | |
223 | } | |
224 | ||
225 | rval = 0; | |
226 | done: | |
227 | mysignal(SIGPIPE, old_sigpipe); | |
228 | if (fd != -1) | |
229 | close(fd); | |
230 | return rval; | |
231 | } | |
232 | ||
dfddba3d | 233 | static int |
234 | seed_from_prngd(unsigned char *buf, size_t bytes) | |
235 | { | |
236 | #ifdef PRNGD_PORT | |
237 | debug("trying egd/prngd port %d", PRNGD_PORT); | |
238 | if (get_random_bytes_prngd(buf, bytes, PRNGD_PORT, NULL) == 0) | |
239 | return 0; | |
240 | #endif | |
241 | #ifdef PRNGD_SOCKET | |
242 | debug("trying egd/prngd socket %s", PRNGD_SOCKET); | |
243 | if (get_random_bytes_prngd(buf, bytes, 0, PRNGD_SOCKET) == 0) | |
244 | return 0; | |
245 | #endif | |
246 | return -1; | |
247 | } | |
248 | ||
d832c38e | 249 | double |
250 | stir_gettimeofday(double entropy_estimate) | |
251 | { | |
252 | struct timeval tv; | |
253 | ||
254 | if (gettimeofday(&tv, NULL) == -1) | |
255 | fatal("Couldn't gettimeofday: %s", strerror(errno)); | |
256 | ||
257 | RAND_add(&tv, sizeof(tv), entropy_estimate); | |
258 | ||
259 | return entropy_estimate; | |
260 | } | |
261 | ||
262 | double | |
263 | stir_clock(double entropy_estimate) | |
264 | { | |
265 | #ifdef HAVE_CLOCK | |
266 | clock_t c; | |
267 | ||
268 | c = clock(); | |
269 | RAND_add(&c, sizeof(c), entropy_estimate); | |
270 | ||
271 | return entropy_estimate; | |
272 | #else /* _HAVE_CLOCK */ | |
273 | return 0; | |
274 | #endif /* _HAVE_CLOCK */ | |
275 | } | |
276 | ||
277 | double | |
278 | stir_rusage(int who, double entropy_estimate) | |
279 | { | |
280 | #ifdef HAVE_GETRUSAGE | |
281 | struct rusage ru; | |
282 | ||
283 | if (getrusage(who, &ru) == -1) | |
284 | return 0; | |
285 | ||
286 | RAND_add(&ru, sizeof(ru), entropy_estimate); | |
287 | ||
288 | return entropy_estimate; | |
289 | #else /* _HAVE_GETRUSAGE */ | |
290 | return 0; | |
291 | #endif /* _HAVE_GETRUSAGE */ | |
292 | } | |
293 | ||
294 | static int | |
295 | timeval_diff(struct timeval *t1, struct timeval *t2) | |
296 | { | |
297 | int secdiff, usecdiff; | |
298 | ||
299 | secdiff = t2->tv_sec - t1->tv_sec; | |
300 | usecdiff = (secdiff*1000000) + (t2->tv_usec - t1->tv_usec); | |
301 | return (int)(usecdiff / 1000); | |
302 | } | |
303 | ||
304 | double | |
d03f4262 | 305 | hash_command_output(entropy_cmd_t *src, unsigned char *hash) |
d832c38e | 306 | { |
307 | char buf[8192]; | |
308 | fd_set rdset; | |
309 | int bytes_read, cmd_eof, error_abort, msec_elapsed, p[2]; | |
310 | int status, total_bytes_read; | |
311 | static int devnull = -1; | |
312 | pid_t pid; | |
313 | SHA_CTX sha; | |
314 | struct timeval tv_start, tv_current; | |
315 | ||
316 | debug3("Reading output from \'%s\'", src->cmdstring); | |
317 | ||
318 | if (devnull == -1) { | |
319 | devnull = open("/dev/null", O_RDWR); | |
320 | if (devnull == -1) | |
540d72c3 | 321 | fatal("Couldn't open /dev/null: %s", |
d832c38e | 322 | strerror(errno)); |
323 | } | |
324 | ||
325 | if (pipe(p) == -1) | |
326 | fatal("Couldn't open pipe: %s", strerror(errno)); | |
327 | ||
328 | (void)gettimeofday(&tv_start, NULL); /* record start time */ | |
329 | ||
330 | switch (pid = fork()) { | |
331 | case -1: /* Error */ | |
332 | close(p[0]); | |
333 | close(p[1]); | |
334 | fatal("Couldn't fork: %s", strerror(errno)); | |
335 | /* NOTREACHED */ | |
336 | case 0: /* Child */ | |
337 | dup2(devnull, STDIN_FILENO); | |
338 | dup2(p[1], STDOUT_FILENO); | |
339 | dup2(p[1], STDERR_FILENO); | |
340 | close(p[0]); | |
341 | close(p[1]); | |
342 | close(devnull); | |
343 | ||
344 | execv(src->path, (char**)(src->args)); | |
345 | ||
540d72c3 | 346 | debug("(child) Couldn't exec '%s': %s", |
d832c38e | 347 | src->cmdstring, strerror(errno)); |
348 | _exit(-1); | |
349 | default: /* Parent */ | |
350 | break; | |
351 | } | |
352 | ||
353 | RAND_add(&pid, sizeof(&pid), 0.0); | |
354 | ||
355 | close(p[1]); | |
356 | ||
357 | /* Hash output from child */ | |
358 | SHA1_Init(&sha); | |
359 | ||
360 | cmd_eof = error_abort = msec_elapsed = total_bytes_read = 0; | |
361 | while (!error_abort && !cmd_eof) { | |
362 | int ret; | |
363 | struct timeval tv; | |
364 | int msec_remaining; | |
365 | ||
366 | (void) gettimeofday(&tv_current, 0); | |
367 | msec_elapsed = timeval_diff(&tv_start, &tv_current); | |
368 | if (msec_elapsed >= entropy_timeout_current) { | |
369 | error_abort=1; | |
370 | continue; | |
371 | } | |
372 | msec_remaining = entropy_timeout_current - msec_elapsed; | |
373 | ||
374 | FD_ZERO(&rdset); | |
375 | FD_SET(p[0], &rdset); | |
376 | tv.tv_sec = msec_remaining / 1000; | |
377 | tv.tv_usec = (msec_remaining % 1000) * 1000; | |
378 | ||
379 | ret = select(p[0] + 1, &rdset, NULL, NULL, &tv); | |
380 | ||
381 | RAND_add(&tv, sizeof(tv), 0.0); | |
382 | ||
383 | switch (ret) { | |
384 | case 0: | |
385 | /* timer expired */ | |
386 | error_abort = 1; | |
bfe49944 | 387 | kill(pid, SIGINT); |
d832c38e | 388 | break; |
389 | case 1: | |
390 | /* command input */ | |
391 | do { | |
392 | bytes_read = read(p[0], buf, sizeof(buf)); | |
393 | } while (bytes_read == -1 && errno == EINTR); | |
394 | RAND_add(&bytes_read, sizeof(&bytes_read), 0.0); | |
395 | if (bytes_read == -1) { | |
396 | error_abort = 1; | |
397 | break; | |
398 | } else if (bytes_read) { | |
399 | SHA1_Update(&sha, buf, bytes_read); | |
400 | total_bytes_read += bytes_read; | |
401 | } else { | |
402 | cmd_eof = 1; | |
403 | } | |
404 | break; | |
405 | case -1: | |
406 | default: | |
407 | /* error */ | |
540d72c3 | 408 | debug("Command '%s': select() failed: %s", |
d832c38e | 409 | src->cmdstring, strerror(errno)); |
410 | error_abort = 1; | |
411 | break; | |
412 | } | |
413 | } | |
414 | ||
415 | SHA1_Final(hash, &sha); | |
416 | ||
417 | close(p[0]); | |
418 | ||
419 | debug3("Time elapsed: %d msec", msec_elapsed); | |
420 | ||
421 | if (waitpid(pid, &status, 0) == -1) { | |
2ce0bfe4 | 422 | error("Couldn't wait for child '%s' completion: %s", |
423 | src->cmdstring, strerror(errno)); | |
d832c38e | 424 | return 0.0; |
425 | } | |
426 | ||
427 | RAND_add(&status, sizeof(&status), 0.0); | |
428 | ||
429 | if (error_abort) { | |
430 | /* | |
431 | * Closing p[0] on timeout causes the entropy command to | |
540d72c3 | 432 | * SIGPIPE. Take whatever output we got, and mark this |
433 | * command as slow | |
d832c38e | 434 | */ |
435 | debug2("Command '%s' timed out", src->cmdstring); | |
436 | src->sticky_badness *= 2; | |
437 | src->badness = src->sticky_badness; | |
438 | return total_bytes_read; | |
439 | } | |
440 | ||
441 | if (WIFEXITED(status)) { | |
442 | if (WEXITSTATUS(status) == 0) { | |
443 | return total_bytes_read; | |
444 | } else { | |
445 | debug2("Command '%s' exit status was %d", | |
446 | src->cmdstring, WEXITSTATUS(status)); | |
447 | src->badness = src->sticky_badness = 128; | |
448 | return 0.0; | |
449 | } | |
450 | } else if (WIFSIGNALED(status)) { | |
451 | debug2("Command '%s' returned on uncaught signal %d !", | |
452 | src->cmdstring, status); | |
453 | src->badness = src->sticky_badness = 128; | |
454 | return 0.0; | |
455 | } else | |
456 | return 0.0; | |
457 | } | |
458 | ||
459 | double | |
460 | stir_from_system(void) | |
461 | { | |
462 | double total_entropy_estimate; | |
463 | long int i; | |
464 | ||
465 | total_entropy_estimate = 0; | |
466 | ||
467 | i = getpid(); | |
468 | RAND_add(&i, sizeof(i), 0.5); | |
469 | total_entropy_estimate += 0.1; | |
470 | ||
471 | i = getppid(); | |
472 | RAND_add(&i, sizeof(i), 0.5); | |
473 | total_entropy_estimate += 0.1; | |
474 | ||
475 | i = getuid(); | |
476 | RAND_add(&i, sizeof(i), 0.0); | |
477 | i = getgid(); | |
478 | RAND_add(&i, sizeof(i), 0.0); | |
479 | ||
480 | total_entropy_estimate += stir_gettimeofday(1.0); | |
481 | total_entropy_estimate += stir_clock(0.5); | |
482 | total_entropy_estimate += stir_rusage(RUSAGE_SELF, 2.0); | |
483 | ||
484 | return total_entropy_estimate; | |
485 | } | |
486 | ||
487 | double | |
488 | stir_from_programs(void) | |
489 | { | |
490 | int c; | |
491 | double entropy, total_entropy; | |
d03f4262 | 492 | unsigned char hash[SHA_DIGEST_LENGTH]; |
d832c38e | 493 | |
494 | total_entropy = 0; | |
495 | for(c = 0; entropy_cmds[c].path != NULL; c++) { | |
496 | if (!entropy_cmds[c].badness) { | |
497 | /* Hash output from command */ | |
498 | entropy = hash_command_output(&entropy_cmds[c], | |
499 | hash); | |
500 | ||
501 | /* Scale back estimate by command's rate */ | |
502 | entropy *= entropy_cmds[c].rate; | |
503 | ||
504 | /* Upper bound of entropy is SHA_DIGEST_LENGTH */ | |
505 | if (entropy > SHA_DIGEST_LENGTH) | |
506 | entropy = SHA_DIGEST_LENGTH; | |
507 | ||
508 | /* Stir it in */ | |
509 | RAND_add(hash, sizeof(hash), entropy); | |
510 | ||
540d72c3 | 511 | debug3("Got %0.2f bytes of entropy from '%s'", |
d832c38e | 512 | entropy, entropy_cmds[c].cmdstring); |
513 | ||
514 | total_entropy += entropy; | |
515 | ||
516 | /* Execution time should be a bit unpredictable */ | |
517 | total_entropy += stir_gettimeofday(0.05); | |
518 | total_entropy += stir_clock(0.05); | |
519 | total_entropy += stir_rusage(RUSAGE_SELF, 0.1); | |
520 | total_entropy += stir_rusage(RUSAGE_CHILDREN, 0.1); | |
521 | } else { | |
522 | debug2("Command '%s' disabled (badness %d)", | |
540d72c3 | 523 | entropy_cmds[c].cmdstring, |
d832c38e | 524 | entropy_cmds[c].badness); |
525 | ||
526 | if (entropy_cmds[c].badness > 0) | |
527 | entropy_cmds[c].badness--; | |
528 | } | |
529 | } | |
530 | ||
531 | return total_entropy; | |
532 | } | |
533 | ||
534 | /* | |
535 | * prng seedfile functions | |
536 | */ | |
537 | int | |
538 | prng_check_seedfile(char *filename) | |
539 | { | |
540 | struct stat st; | |
541 | ||
542 | /* | |
540d72c3 | 543 | * XXX raceable: eg replace seed between this stat and subsequent |
544 | * open. Not such a problem because we don't really trust the | |
d832c38e | 545 | * seed file anyway. |
546 | * XXX: use secure path checking as elsewhere in OpenSSH | |
547 | */ | |
548 | if (lstat(filename, &st) == -1) { | |
549 | /* Give up on hard errors */ | |
550 | if (errno != ENOENT) | |
551 | debug("WARNING: Couldn't stat random seed file " | |
552 | "\"%.100s\": %s", filename, strerror(errno)); | |
553 | return 0; | |
554 | } | |
555 | ||
556 | /* regular file? */ | |
557 | if (!S_ISREG(st.st_mode)) | |
558 | fatal("PRNG seedfile %.100s is not a regular file", | |
559 | filename); | |
560 | ||
561 | /* mode 0600, owned by root or the current user? */ | |
562 | if (((st.st_mode & 0177) != 0) || !(st.st_uid == getuid())) { | |
563 | debug("WARNING: PRNG seedfile %.100s must be mode 0600, " | |
7cac2b65 | 564 | "owned by uid %li", filename, (long int)getuid()); |
d832c38e | 565 | return 0; |
566 | } | |
567 | ||
568 | return 1; | |
569 | } | |
570 | ||
571 | void | |
572 | prng_write_seedfile(void) | |
573 | { | |
dfddba3d | 574 | int fd, save_errno; |
d03f4262 | 575 | unsigned char seed[SEED_FILE_SIZE]; |
dfddba3d | 576 | char filename[MAXPATHLEN], tmpseed[MAXPATHLEN]; |
d832c38e | 577 | struct passwd *pw; |
dfddba3d | 578 | mode_t old_umask; |
d832c38e | 579 | |
580 | pw = getpwuid(getuid()); | |
581 | if (pw == NULL) | |
582 | fatal("Couldn't get password entry for current user " | |
7cac2b65 | 583 | "(%li): %s", (long int)getuid(), strerror(errno)); |
d832c38e | 584 | |
585 | /* Try to ensure that the parent directory is there */ | |
586 | snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir, | |
587 | _PATH_SSH_USER_DIR); | |
30460aeb | 588 | if (mkdir(filename, 0700) < 0 && errno != EEXIST) |
589 | fatal("mkdir %.200s: %s", filename, strerror(errno)); | |
d832c38e | 590 | |
591 | snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir, | |
592 | SSH_PRNG_SEED_FILE); | |
593 | ||
dfddba3d | 594 | strlcpy(tmpseed, filename, sizeof(tmpseed)); |
595 | if (strlcat(tmpseed, ".XXXXXXXXXX", sizeof(tmpseed)) >= | |
596 | sizeof(tmpseed)) | |
597 | fatal("PRNG seed filename too long"); | |
d832c38e | 598 | |
bfe49944 | 599 | if (RAND_bytes(seed, sizeof(seed)) <= 0) |
540d72c3 | 600 | fatal("PRNG seed extraction failed"); |
d832c38e | 601 | |
602 | /* Don't care if the seed doesn't exist */ | |
603 | prng_check_seedfile(filename); | |
604 | ||
dfddba3d | 605 | old_umask = umask(0177); |
606 | ||
607 | if ((fd = mkstemp(tmpseed)) == -1) { | |
608 | debug("WARNING: couldn't make temporary PRNG seedfile %.100s " | |
609 | "(%.100s)", tmpseed, strerror(errno)); | |
d832c38e | 610 | } else { |
dfddba3d | 611 | debug("writing PRNG seed to file %.100s", tmpseed); |
612 | if (atomicio(vwrite, fd, &seed, sizeof(seed)) < sizeof(seed)) { | |
613 | save_errno = errno; | |
614 | close(fd); | |
615 | unlink(tmpseed); | |
d832c38e | 616 | fatal("problem writing PRNG seedfile %.100s " |
dfddba3d | 617 | "(%.100s)", filename, strerror(save_errno)); |
618 | } | |
d832c38e | 619 | close(fd); |
dfddba3d | 620 | debug("moving temporary PRNG seed to file %.100s", filename); |
621 | if (rename(tmpseed, filename) == -1) { | |
622 | save_errno = errno; | |
623 | unlink(tmpseed); | |
624 | fatal("problem renaming PRNG seedfile from %.100s " | |
2ce0bfe4 | 625 | "to %.100s (%.100s)", tmpseed, filename, |
dfddba3d | 626 | strerror(save_errno)); |
627 | } | |
d832c38e | 628 | } |
dfddba3d | 629 | umask(old_umask); |
d832c38e | 630 | } |
631 | ||
632 | void | |
633 | prng_read_seedfile(void) | |
634 | { | |
635 | int fd; | |
636 | char seed[SEED_FILE_SIZE], filename[MAXPATHLEN]; | |
637 | struct passwd *pw; | |
638 | ||
639 | pw = getpwuid(getuid()); | |
640 | if (pw == NULL) | |
641 | fatal("Couldn't get password entry for current user " | |
7cac2b65 | 642 | "(%li): %s", (long int)getuid(), strerror(errno)); |
d832c38e | 643 | |
644 | snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir, | |
645 | SSH_PRNG_SEED_FILE); | |
646 | ||
647 | debug("loading PRNG seed from file %.100s", filename); | |
648 | ||
649 | if (!prng_check_seedfile(filename)) { | |
650 | verbose("Random seed file not found or invalid, ignoring."); | |
651 | return; | |
652 | } | |
653 | ||
654 | /* open the file and read in the seed */ | |
655 | fd = open(filename, O_RDONLY); | |
656 | if (fd == -1) | |
657 | fatal("could not open PRNG seedfile %.100s (%.100s)", | |
658 | filename, strerror(errno)); | |
659 | ||
660 | if (atomicio(read, fd, &seed, sizeof(seed)) < sizeof(seed)) { | |
661 | verbose("invalid or short read from PRNG seedfile " | |
662 | "%.100s - ignoring", filename); | |
663 | memset(seed, '\0', sizeof(seed)); | |
664 | } | |
665 | close(fd); | |
666 | ||
667 | /* stir in the seed, with estimated entropy zero */ | |
668 | RAND_add(&seed, sizeof(seed), 0.0); | |
669 | } | |
670 | ||
671 | ||
672 | /* | |
673 | * entropy command initialisation functions | |
674 | */ | |
675 | int | |
676 | prng_read_commands(char *cmdfilename) | |
677 | { | |
678 | char cmd[SEED_FILE_SIZE], *cp, line[1024], path[SEED_FILE_SIZE]; | |
679 | double est; | |
680 | entropy_cmd_t *entcmd; | |
681 | FILE *f; | |
682 | int cur_cmd, linenum, num_cmds, arg; | |
683 | ||
684 | if ((f = fopen(cmdfilename, "r")) == NULL) { | |
685 | fatal("couldn't read entropy commands file %.100s: %.100s", | |
686 | cmdfilename, strerror(errno)); | |
687 | } | |
688 | ||
689 | num_cmds = 64; | |
30460aeb | 690 | entcmd = xcalloc(num_cmds, sizeof(entropy_cmd_t)); |
d832c38e | 691 | |
692 | /* Read in file */ | |
693 | cur_cmd = linenum = 0; | |
694 | while (fgets(line, sizeof(line), f)) { | |
695 | linenum++; | |
696 | ||
697 | /* Skip leading whitespace, blank lines and comments */ | |
698 | cp = line + strspn(line, WHITESPACE); | |
699 | if ((*cp == 0) || (*cp == '#')) | |
700 | continue; /* done with this line */ | |
701 | ||
702 | /* | |
540d72c3 | 703 | * The first non-whitespace char should be a double quote |
d832c38e | 704 | * delimiting the commandline |
705 | */ | |
706 | if (*cp != '"') { | |
707 | error("bad entropy command, %.100s line %d", | |
708 | cmdfilename, linenum); | |
709 | continue; | |
710 | } | |
711 | ||
712 | /* | |
713 | * First token, command args (incl. argv[0]) in double | |
714 | * quotes | |
715 | */ | |
716 | cp = strtok(cp, "\""); | |
717 | if (cp == NULL) { | |
718 | error("missing or bad command string, %.100s " | |
719 | "line %d -- ignored", cmdfilename, linenum); | |
720 | continue; | |
721 | } | |
722 | strlcpy(cmd, cp, sizeof(cmd)); | |
723 | ||
724 | /* Second token, full command path */ | |
725 | if ((cp = strtok(NULL, WHITESPACE)) == NULL) { | |
726 | error("missing command path, %.100s " | |
727 | "line %d -- ignored", cmdfilename, linenum); | |
728 | continue; | |
729 | } | |
730 | ||
731 | /* Did configure mark this as dead? */ | |
732 | if (strncmp("undef", cp, 5) == 0) | |
733 | continue; | |
734 | ||
735 | strlcpy(path, cp, sizeof(path)); | |
736 | ||
737 | /* Third token, entropy rate estimate for this command */ | |
738 | if ((cp = strtok(NULL, WHITESPACE)) == NULL) { | |
739 | error("missing entropy estimate, %.100s " | |
740 | "line %d -- ignored", cmdfilename, linenum); | |
741 | continue; | |
742 | } | |
743 | est = strtod(cp, NULL); | |
744 | ||
745 | /* end of line */ | |
746 | if ((cp = strtok(NULL, WHITESPACE)) != NULL) { | |
747 | error("garbage at end of line %d in %.100s " | |
748 | "-- ignored", linenum, cmdfilename); | |
749 | continue; | |
750 | } | |
751 | ||
752 | /* save the command for debug messages */ | |
753 | entcmd[cur_cmd].cmdstring = xstrdup(cmd); | |
754 | ||
755 | /* split the command args */ | |
756 | cp = strtok(cmd, WHITESPACE); | |
757 | arg = 0; | |
758 | do { | |
759 | entcmd[cur_cmd].args[arg] = xstrdup(cp); | |
760 | arg++; | |
761 | } while(arg < NUM_ARGS && (cp = strtok(NULL, WHITESPACE))); | |
762 | ||
763 | if (strtok(NULL, WHITESPACE)) | |
764 | error("ignored extra commands (max %d), %.100s " | |
765 | "line %d", NUM_ARGS, cmdfilename, linenum); | |
766 | ||
767 | /* Copy the command path and rate estimate */ | |
768 | entcmd[cur_cmd].path = xstrdup(path); | |
769 | entcmd[cur_cmd].rate = est; | |
770 | ||
771 | /* Initialise other values */ | |
772 | entcmd[cur_cmd].sticky_badness = 1; | |
773 | ||
774 | cur_cmd++; | |
775 | ||
776 | /* | |
777 | * If we've filled the array, reallocate it twice the size | |
540d72c3 | 778 | * Do this now because even if this we're on the last |
d832c38e | 779 | * command we need another slot to mark the last entry |
780 | */ | |
781 | if (cur_cmd == num_cmds) { | |
782 | num_cmds *= 2; | |
30460aeb | 783 | entcmd = xrealloc(entcmd, num_cmds, |
d832c38e | 784 | sizeof(entropy_cmd_t)); |
785 | } | |
786 | } | |
787 | ||
788 | /* zero the last entry */ | |
789 | memset(&entcmd[cur_cmd], '\0', sizeof(entropy_cmd_t)); | |
790 | ||
791 | /* trim to size */ | |
30460aeb | 792 | entropy_cmds = xrealloc(entcmd, (cur_cmd + 1), |
d832c38e | 793 | sizeof(entropy_cmd_t)); |
794 | ||
795 | debug("Loaded %d entropy commands from %.100s", cur_cmd, | |
796 | cmdfilename); | |
797 | ||
30460aeb | 798 | fclose(f); |
d832c38e | 799 | return cur_cmd < MIN_ENTROPY_SOURCES ? -1 : 0; |
800 | } | |
801 | ||
350391c5 | 802 | void |
803 | usage(void) | |
804 | { | |
805 | fprintf(stderr, "Usage: %s [options]\n", __progname); | |
806 | fprintf(stderr, " -v Verbose; display verbose debugging messages.\n"); | |
807 | fprintf(stderr, " Multiple -v increases verbosity.\n"); | |
dfddba3d | 808 | fprintf(stderr, " -x Force output in hexadecimal (for debugging)\n"); |
350391c5 | 809 | fprintf(stderr, " -X Force output in binary\n"); |
810 | fprintf(stderr, " -b bytes Number of bytes to output (default %d)\n", | |
811 | OUTPUT_SEED_SIZE); | |
812 | } | |
813 | ||
540d72c3 | 814 | int |
d832c38e | 815 | main(int argc, char **argv) |
816 | { | |
350391c5 | 817 | unsigned char *buf; |
818 | int ret, ch, debug_level, output_hex, bytes; | |
819 | extern char *optarg; | |
820 | LogLevel ll; | |
d832c38e | 821 | |
7cac2b65 | 822 | __progname = ssh_get_progname(argv[0]); |
d832c38e | 823 | log_init(argv[0], SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_USER, 1); |
824 | ||
350391c5 | 825 | ll = SYSLOG_LEVEL_INFO; |
826 | debug_level = output_hex = 0; | |
827 | bytes = OUTPUT_SEED_SIZE; | |
828 | ||
829 | /* Don't write binary data to a tty, unless we are forced to */ | |
830 | if (isatty(STDOUT_FILENO)) | |
831 | output_hex = 1; | |
540d72c3 | 832 | |
350391c5 | 833 | while ((ch = getopt(argc, argv, "vxXhb:")) != -1) { |
834 | switch (ch) { | |
835 | case 'v': | |
836 | if (debug_level < 3) | |
837 | ll = SYSLOG_LEVEL_DEBUG1 + debug_level++; | |
838 | break; | |
839 | case 'x': | |
840 | output_hex = 1; | |
841 | break; | |
842 | case 'X': | |
843 | output_hex = 0; | |
844 | break; | |
845 | case 'b': | |
846 | if ((bytes = atoi(optarg)) <= 0) | |
847 | fatal("Invalid number of output bytes"); | |
848 | break; | |
849 | case 'h': | |
850 | usage(); | |
851 | exit(0); | |
852 | default: | |
853 | error("Invalid commandline option"); | |
854 | usage(); | |
855 | } | |
856 | } | |
857 | ||
858 | log_init(argv[0], ll, SYSLOG_FACILITY_USER, 1); | |
540d72c3 | 859 | |
d832c38e | 860 | #ifdef USE_SEED_FILES |
861 | prng_read_seedfile(); | |
862 | #endif | |
863 | ||
350391c5 | 864 | buf = xmalloc(bytes); |
865 | ||
d832c38e | 866 | /* |
867 | * Seed the RNG from wherever we can | |
868 | */ | |
540d72c3 | 869 | |
d832c38e | 870 | /* Take whatever is on the stack, but don't credit it */ |
350391c5 | 871 | RAND_add(buf, bytes, 0); |
d832c38e | 872 | |
540d72c3 | 873 | debug("Seeded RNG with %i bytes from system calls", |
d832c38e | 874 | (int)stir_from_system()); |
875 | ||
dfddba3d | 876 | /* try prngd, fall back to commands if prngd fails or not configured */ |
877 | if (seed_from_prngd(buf, bytes) == 0) { | |
878 | RAND_add(buf, bytes, bytes); | |
879 | } else { | |
880 | /* Read in collection commands */ | |
881 | if (prng_read_commands(SSH_PRNG_COMMAND_FILE) == -1) | |
882 | fatal("PRNG initialisation failed -- exiting."); | |
883 | debug("Seeded RNG with %i bytes from programs", | |
884 | (int)stir_from_programs()); | |
885 | } | |
d832c38e | 886 | |
887 | #ifdef USE_SEED_FILES | |
888 | prng_write_seedfile(); | |
889 | #endif | |
890 | ||
891 | /* | |
892 | * Write the seed to stdout | |
893 | */ | |
894 | ||
895 | if (!RAND_status()) | |
896 | fatal("Not enough entropy in RNG"); | |
897 | ||
bfe49944 | 898 | if (RAND_bytes(buf, bytes) <= 0) |
899 | fatal("Couldn't extract entropy from PRNG"); | |
d832c38e | 900 | |
350391c5 | 901 | if (output_hex) { |
902 | for(ret = 0; ret < bytes; ret++) | |
903 | printf("%02x", (unsigned char)(buf[ret])); | |
904 | printf("\n"); | |
905 | } else | |
7cac2b65 | 906 | ret = atomicio(vwrite, STDOUT_FILENO, buf, bytes); |
540d72c3 | 907 | |
350391c5 | 908 | memset(buf, '\0', bytes); |
909 | xfree(buf); | |
540d72c3 | 910 | |
350391c5 | 911 | return ret == bytes ? 0 : 1; |
d832c38e | 912 | } |
dfddba3d | 913 | |
914 | /* | |
915 | * We may attempt to re-seed during mkstemp if we are using the one in the | |
916 | * compat library (via mkstemp -> _gettemp -> arc4random -> seed_rng) so we | |
917 | * need our own seed_rng(). We must also check that we have enough entropy. | |
918 | */ | |
919 | void | |
920 | seed_rng(void) | |
921 | { | |
922 | if (!RAND_status()) | |
923 | fatal("Not enough entropy in RNG"); | |
924 | } |