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46058ce2 | 1 | /* |
40f64e6f | 2 | * Copyright (c) 2001-2002 Damien Miller. All rights reserved. |
46058ce2 | 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 | ||
cb2c6179 | 27 | #include <sys/types.h> |
28 | #include <sys/resource.h> | |
29 | #include <sys/stat.h> | |
30 | #include <sys/wait.h> | |
31 | ||
32 | #ifdef HAVE_SYS_UN_H | |
33 | # include <sys/un.h> | |
34 | #endif | |
35 | ||
36 | #include <signal.h> | |
37 | ||
46058ce2 | 38 | #include <openssl/rand.h> |
39 | #include <openssl/sha.h> | |
40 | #include <openssl/crypto.h> | |
41 | ||
42 | /* SunOS 4.4.4 needs this */ | |
43 | #ifdef HAVE_FLOATINGPOINT_H | |
44 | # include <floatingpoint.h> | |
45 | #endif /* HAVE_FLOATINGPOINT_H */ | |
46 | ||
47 | #include "misc.h" | |
48 | #include "xmalloc.h" | |
49 | #include "atomicio.h" | |
50 | #include "pathnames.h" | |
51 | #include "log.h" | |
52 | ||
40f64e6f | 53 | /* Number of bytes we write out */ |
54 | #define OUTPUT_SEED_SIZE 48 | |
55 | ||
56 | /* Length of on-disk seedfiles */ | |
57 | #define SEED_FILE_SIZE 1024 | |
58 | ||
59 | /* Maximum number of command-line arguments to read from file */ | |
60 | #define NUM_ARGS 10 | |
61 | ||
62 | /* Minimum number of usable commands to be considered sufficient */ | |
63 | #define MIN_ENTROPY_SOURCES 16 | |
46058ce2 | 64 | |
40f64e6f | 65 | /* Path to on-disk seed file (relative to user's home directory */ |
46058ce2 | 66 | #ifndef SSH_PRNG_SEED_FILE |
67 | # define SSH_PRNG_SEED_FILE _PATH_SSH_USER_DIR"/prng_seed" | |
40f64e6f | 68 | #endif |
69 | ||
70 | /* Path to PRNG commands list */ | |
46058ce2 | 71 | #ifndef SSH_PRNG_COMMAND_FILE |
2a8a6488 | 72 | # define SSH_PRNG_COMMAND_FILE SSHDIR "/ssh_prng_cmds" |
40f64e6f | 73 | #endif |
46058ce2 | 74 | |
40f64e6f | 75 | extern char *__progname; |
40f64e6f | 76 | |
46058ce2 | 77 | #define WHITESPACE " \t\n" |
78 | ||
79 | #ifndef RUSAGE_SELF | |
80 | # define RUSAGE_SELF 0 | |
81 | #endif | |
82 | #ifndef RUSAGE_CHILDREN | |
83 | # define RUSAGE_CHILDREN 0 | |
84 | #endif | |
85 | ||
49d7ed32 | 86 | #if !defined(PRNGD_SOCKET) && !defined(PRNGD_PORT) |
40f64e6f | 87 | # define USE_SEED_FILES |
46058ce2 | 88 | #endif |
89 | ||
40f64e6f | 90 | typedef struct { |
91 | /* Proportion of data that is entropy */ | |
92 | double rate; | |
93 | /* Counter goes positive if this command times out */ | |
94 | unsigned int badness; | |
95 | /* Increases by factor of two each timeout */ | |
96 | unsigned int sticky_badness; | |
97 | /* Path to executable */ | |
98 | char *path; | |
99 | /* argv to pass to executable */ | |
100 | char *args[NUM_ARGS]; /* XXX: arbitrary limit */ | |
101 | /* full command string (debug) */ | |
102 | char *cmdstring; | |
103 | } entropy_cmd_t; | |
104 | ||
105 | /* slow command timeouts (all in milliseconds) */ | |
106 | /* static int entropy_timeout_default = ENTROPY_TIMEOUT_MSEC; */ | |
107 | static int entropy_timeout_current = ENTROPY_TIMEOUT_MSEC; | |
108 | ||
109 | /* this is initialised from a file, by prng_read_commands() */ | |
110 | static entropy_cmd_t *entropy_cmds = NULL; | |
111 | ||
112 | /* Prototypes */ | |
113 | double stir_from_system(void); | |
114 | double stir_from_programs(void); | |
115 | double stir_gettimeofday(double entropy_estimate); | |
116 | double stir_clock(double entropy_estimate); | |
117 | double stir_rusage(int who, double entropy_estimate); | |
75131bbd | 118 | double hash_command_output(entropy_cmd_t *src, unsigned char *hash); |
aff51935 | 119 | int get_random_bytes_prngd(unsigned char *buf, int len, |
40f64e6f | 120 | unsigned short tcp_port, char *socket_path); |
121 | ||
122 | /* | |
123 | * Collect 'len' bytes of entropy into 'buf' from PRNGD/EGD daemon | |
124 | * listening either on 'tcp_port', or via Unix domain socket at * | |
125 | * 'socket_path'. | |
aff51935 | 126 | * Either a non-zero tcp_port or a non-null socket_path must be |
40f64e6f | 127 | * supplied. |
128 | * Returns 0 on success, -1 on error | |
129 | */ | |
46058ce2 | 130 | int |
aff51935 | 131 | get_random_bytes_prngd(unsigned char *buf, int len, |
40f64e6f | 132 | unsigned short tcp_port, char *socket_path) |
46058ce2 | 133 | { |
40f64e6f | 134 | int fd, addr_len, rval, errors; |
44d71ad5 | 135 | u_char msg[2]; |
40f64e6f | 136 | struct sockaddr_storage addr; |
137 | struct sockaddr_in *addr_in = (struct sockaddr_in *)&addr; | |
138 | struct sockaddr_un *addr_un = (struct sockaddr_un *)&addr; | |
46058ce2 | 139 | mysig_t old_sigpipe; |
140 | ||
40f64e6f | 141 | /* Sanity checks */ |
142 | if (socket_path == NULL && tcp_port == 0) | |
143 | fatal("You must specify a port or a socket"); | |
144 | if (socket_path != NULL && | |
145 | strlen(socket_path) >= sizeof(addr_un->sun_path)) | |
146 | fatal("Random pool path is too long"); | |
44d71ad5 | 147 | if (len <= 0 || len > 255) |
148 | fatal("Too many bytes (%d) to read from PRNGD", len); | |
46058ce2 | 149 | |
150 | memset(&addr, '\0', sizeof(addr)); | |
151 | ||
40f64e6f | 152 | if (tcp_port != 0) { |
153 | addr_in->sin_family = AF_INET; | |
154 | addr_in->sin_addr.s_addr = htonl(INADDR_LOOPBACK); | |
155 | addr_in->sin_port = htons(tcp_port); | |
156 | addr_len = sizeof(*addr_in); | |
157 | } else { | |
158 | addr_un->sun_family = AF_UNIX; | |
159 | strlcpy(addr_un->sun_path, socket_path, | |
160 | sizeof(addr_un->sun_path)); | |
161 | addr_len = offsetof(struct sockaddr_un, sun_path) + | |
162 | strlen(socket_path) + 1; | |
163 | } | |
46058ce2 | 164 | |
165 | old_sigpipe = mysignal(SIGPIPE, SIG_IGN); | |
166 | ||
40f64e6f | 167 | errors = 0; |
168 | rval = -1; | |
46058ce2 | 169 | reopen: |
40f64e6f | 170 | fd = socket(addr.ss_family, SOCK_STREAM, 0); |
46058ce2 | 171 | if (fd == -1) { |
40f64e6f | 172 | error("Couldn't create socket: %s", strerror(errno)); |
46058ce2 | 173 | goto done; |
174 | } | |
46058ce2 | 175 | |
176 | if (connect(fd, (struct sockaddr*)&addr, addr_len) == -1) { | |
40f64e6f | 177 | if (tcp_port != 0) { |
178 | error("Couldn't connect to PRNGD port %d: %s", | |
179 | tcp_port, strerror(errno)); | |
180 | } else { | |
181 | error("Couldn't connect to PRNGD socket \"%s\": %s", | |
182 | addr_un->sun_path, strerror(errno)); | |
183 | } | |
46058ce2 | 184 | goto done; |
185 | } | |
186 | ||
187 | /* Send blocking read request to PRNGD */ | |
188 | msg[0] = 0x02; | |
189 | msg[1] = len; | |
190 | ||
d72f7b79 | 191 | if (atomicio(vwrite, fd, msg, sizeof(msg)) != sizeof(msg)) { |
46058ce2 | 192 | if (errno == EPIPE && errors < 10) { |
193 | close(fd); | |
194 | errors++; | |
195 | goto reopen; | |
196 | } | |
197 | error("Couldn't write to PRNGD socket: %s", | |
198 | strerror(errno)); | |
199 | goto done; | |
200 | } | |
201 | ||
44d71ad5 | 202 | if (atomicio(read, fd, buf, len) != (size_t)len) { |
46058ce2 | 203 | if (errno == EPIPE && errors < 10) { |
204 | close(fd); | |
205 | errors++; | |
206 | goto reopen; | |
207 | } | |
208 | error("Couldn't read from PRNGD socket: %s", | |
209 | strerror(errno)); | |
210 | goto done; | |
211 | } | |
212 | ||
40f64e6f | 213 | rval = 0; |
46058ce2 | 214 | done: |
215 | mysignal(SIGPIPE, old_sigpipe); | |
216 | if (fd != -1) | |
217 | close(fd); | |
40f64e6f | 218 | return rval; |
46058ce2 | 219 | } |
220 | ||
1e111f05 | 221 | static int |
222 | seed_from_prngd(unsigned char *buf, size_t bytes) | |
223 | { | |
224 | #ifdef PRNGD_PORT | |
225 | debug("trying egd/prngd port %d", PRNGD_PORT); | |
226 | if (get_random_bytes_prngd(buf, bytes, PRNGD_PORT, NULL) == 0) | |
227 | return 0; | |
228 | #endif | |
229 | #ifdef PRNGD_SOCKET | |
230 | debug("trying egd/prngd socket %s", PRNGD_SOCKET); | |
231 | if (get_random_bytes_prngd(buf, bytes, 0, PRNGD_SOCKET) == 0) | |
232 | return 0; | |
233 | #endif | |
234 | return -1; | |
235 | } | |
236 | ||
46058ce2 | 237 | double |
238 | stir_gettimeofday(double entropy_estimate) | |
239 | { | |
240 | struct timeval tv; | |
241 | ||
242 | if (gettimeofday(&tv, NULL) == -1) | |
243 | fatal("Couldn't gettimeofday: %s", strerror(errno)); | |
244 | ||
245 | RAND_add(&tv, sizeof(tv), entropy_estimate); | |
246 | ||
40f64e6f | 247 | return entropy_estimate; |
46058ce2 | 248 | } |
249 | ||
250 | double | |
251 | stir_clock(double entropy_estimate) | |
252 | { | |
253 | #ifdef HAVE_CLOCK | |
254 | clock_t c; | |
255 | ||
256 | c = clock(); | |
257 | RAND_add(&c, sizeof(c), entropy_estimate); | |
258 | ||
40f64e6f | 259 | return entropy_estimate; |
46058ce2 | 260 | #else /* _HAVE_CLOCK */ |
40f64e6f | 261 | return 0; |
46058ce2 | 262 | #endif /* _HAVE_CLOCK */ |
263 | } | |
264 | ||
265 | double | |
266 | stir_rusage(int who, double entropy_estimate) | |
267 | { | |
268 | #ifdef HAVE_GETRUSAGE | |
269 | struct rusage ru; | |
270 | ||
271 | if (getrusage(who, &ru) == -1) | |
40f64e6f | 272 | return 0; |
46058ce2 | 273 | |
274 | RAND_add(&ru, sizeof(ru), entropy_estimate); | |
275 | ||
40f64e6f | 276 | return entropy_estimate; |
46058ce2 | 277 | #else /* _HAVE_GETRUSAGE */ |
40f64e6f | 278 | return 0; |
46058ce2 | 279 | #endif /* _HAVE_GETRUSAGE */ |
280 | } | |
281 | ||
46058ce2 | 282 | static int |
40f64e6f | 283 | timeval_diff(struct timeval *t1, struct timeval *t2) |
284 | { | |
46058ce2 | 285 | int secdiff, usecdiff; |
286 | ||
287 | secdiff = t2->tv_sec - t1->tv_sec; | |
288 | usecdiff = (secdiff*1000000) + (t2->tv_usec - t1->tv_usec); | |
289 | return (int)(usecdiff / 1000); | |
290 | } | |
291 | ||
292 | double | |
75131bbd | 293 | hash_command_output(entropy_cmd_t *src, unsigned char *hash) |
46058ce2 | 294 | { |
40f64e6f | 295 | char buf[8192]; |
46058ce2 | 296 | fd_set rdset; |
40f64e6f | 297 | int bytes_read, cmd_eof, error_abort, msec_elapsed, p[2]; |
298 | int status, total_bytes_read; | |
299 | static int devnull = -1; | |
46058ce2 | 300 | pid_t pid; |
46058ce2 | 301 | SHA_CTX sha; |
40f64e6f | 302 | struct timeval tv_start, tv_current; |
46058ce2 | 303 | |
304 | debug3("Reading output from \'%s\'", src->cmdstring); | |
305 | ||
306 | if (devnull == -1) { | |
307 | devnull = open("/dev/null", O_RDWR); | |
308 | if (devnull == -1) | |
aff51935 | 309 | fatal("Couldn't open /dev/null: %s", |
40f64e6f | 310 | strerror(errno)); |
46058ce2 | 311 | } |
312 | ||
313 | if (pipe(p) == -1) | |
314 | fatal("Couldn't open pipe: %s", strerror(errno)); | |
315 | ||
316 | (void)gettimeofday(&tv_start, NULL); /* record start time */ | |
317 | ||
318 | switch (pid = fork()) { | |
319 | case -1: /* Error */ | |
320 | close(p[0]); | |
321 | close(p[1]); | |
322 | fatal("Couldn't fork: %s", strerror(errno)); | |
323 | /* NOTREACHED */ | |
324 | case 0: /* Child */ | |
325 | dup2(devnull, STDIN_FILENO); | |
326 | dup2(p[1], STDOUT_FILENO); | |
327 | dup2(p[1], STDERR_FILENO); | |
328 | close(p[0]); | |
329 | close(p[1]); | |
330 | close(devnull); | |
331 | ||
332 | execv(src->path, (char**)(src->args)); | |
40f64e6f | 333 | |
aff51935 | 334 | debug("(child) Couldn't exec '%s': %s", |
40f64e6f | 335 | src->cmdstring, strerror(errno)); |
46058ce2 | 336 | _exit(-1); |
337 | default: /* Parent */ | |
338 | break; | |
339 | } | |
340 | ||
341 | RAND_add(&pid, sizeof(&pid), 0.0); | |
342 | ||
343 | close(p[1]); | |
344 | ||
345 | /* Hash output from child */ | |
346 | SHA1_Init(&sha); | |
46058ce2 | 347 | |
40f64e6f | 348 | cmd_eof = error_abort = msec_elapsed = total_bytes_read = 0; |
46058ce2 | 349 | while (!error_abort && !cmd_eof) { |
350 | int ret; | |
351 | struct timeval tv; | |
352 | int msec_remaining; | |
353 | ||
354 | (void) gettimeofday(&tv_current, 0); | |
40f64e6f | 355 | msec_elapsed = timeval_diff(&tv_start, &tv_current); |
46058ce2 | 356 | if (msec_elapsed >= entropy_timeout_current) { |
357 | error_abort=1; | |
358 | continue; | |
359 | } | |
360 | msec_remaining = entropy_timeout_current - msec_elapsed; | |
361 | ||
362 | FD_ZERO(&rdset); | |
363 | FD_SET(p[0], &rdset); | |
40f64e6f | 364 | tv.tv_sec = msec_remaining / 1000; |
46058ce2 | 365 | tv.tv_usec = (msec_remaining % 1000) * 1000; |
366 | ||
40f64e6f | 367 | ret = select(p[0] + 1, &rdset, NULL, NULL, &tv); |
46058ce2 | 368 | |
369 | RAND_add(&tv, sizeof(tv), 0.0); | |
370 | ||
371 | switch (ret) { | |
372 | case 0: | |
373 | /* timer expired */ | |
374 | error_abort = 1; | |
4e6f1c4f | 375 | kill(pid, SIGINT); |
46058ce2 | 376 | break; |
377 | case 1: | |
378 | /* command input */ | |
379 | do { | |
380 | bytes_read = read(p[0], buf, sizeof(buf)); | |
381 | } while (bytes_read == -1 && errno == EINTR); | |
382 | RAND_add(&bytes_read, sizeof(&bytes_read), 0.0); | |
383 | if (bytes_read == -1) { | |
384 | error_abort = 1; | |
385 | break; | |
386 | } else if (bytes_read) { | |
387 | SHA1_Update(&sha, buf, bytes_read); | |
388 | total_bytes_read += bytes_read; | |
389 | } else { | |
390 | cmd_eof = 1; | |
391 | } | |
392 | break; | |
393 | case -1: | |
394 | default: | |
395 | /* error */ | |
aff51935 | 396 | debug("Command '%s': select() failed: %s", |
40f64e6f | 397 | src->cmdstring, strerror(errno)); |
46058ce2 | 398 | error_abort = 1; |
399 | break; | |
400 | } | |
401 | } | |
402 | ||
403 | SHA1_Final(hash, &sha); | |
404 | ||
405 | close(p[0]); | |
406 | ||
407 | debug3("Time elapsed: %d msec", msec_elapsed); | |
408 | ||
409 | if (waitpid(pid, &status, 0) == -1) { | |
98c044d0 | 410 | error("Couldn't wait for child '%s' completion: %s", |
411 | src->cmdstring, strerror(errno)); | |
40f64e6f | 412 | return 0.0; |
46058ce2 | 413 | } |
414 | ||
415 | RAND_add(&status, sizeof(&status), 0.0); | |
416 | ||
417 | if (error_abort) { | |
40f64e6f | 418 | /* |
419 | * Closing p[0] on timeout causes the entropy command to | |
aff51935 | 420 | * SIGPIPE. Take whatever output we got, and mark this |
421 | * command as slow | |
40f64e6f | 422 | */ |
46058ce2 | 423 | debug2("Command '%s' timed out", src->cmdstring); |
424 | src->sticky_badness *= 2; | |
425 | src->badness = src->sticky_badness; | |
40f64e6f | 426 | return total_bytes_read; |
46058ce2 | 427 | } |
428 | ||
429 | if (WIFEXITED(status)) { | |
40f64e6f | 430 | if (WEXITSTATUS(status) == 0) { |
431 | return total_bytes_read; | |
46058ce2 | 432 | } else { |
40f64e6f | 433 | debug2("Command '%s' exit status was %d", |
434 | src->cmdstring, WEXITSTATUS(status)); | |
46058ce2 | 435 | src->badness = src->sticky_badness = 128; |
40f64e6f | 436 | return 0.0; |
46058ce2 | 437 | } |
438 | } else if (WIFSIGNALED(status)) { | |
40f64e6f | 439 | debug2("Command '%s' returned on uncaught signal %d !", |
440 | src->cmdstring, status); | |
46058ce2 | 441 | src->badness = src->sticky_badness = 128; |
40f64e6f | 442 | return 0.0; |
46058ce2 | 443 | } else |
40f64e6f | 444 | return 0.0; |
445 | } | |
446 | ||
447 | double | |
448 | stir_from_system(void) | |
449 | { | |
450 | double total_entropy_estimate; | |
451 | long int i; | |
452 | ||
453 | total_entropy_estimate = 0; | |
454 | ||
455 | i = getpid(); | |
456 | RAND_add(&i, sizeof(i), 0.5); | |
457 | total_entropy_estimate += 0.1; | |
458 | ||
459 | i = getppid(); | |
460 | RAND_add(&i, sizeof(i), 0.5); | |
461 | total_entropy_estimate += 0.1; | |
462 | ||
463 | i = getuid(); | |
464 | RAND_add(&i, sizeof(i), 0.0); | |
465 | i = getgid(); | |
466 | RAND_add(&i, sizeof(i), 0.0); | |
467 | ||
468 | total_entropy_estimate += stir_gettimeofday(1.0); | |
469 | total_entropy_estimate += stir_clock(0.5); | |
470 | total_entropy_estimate += stir_rusage(RUSAGE_SELF, 2.0); | |
471 | ||
472 | return total_entropy_estimate; | |
473 | } | |
474 | ||
475 | double | |
476 | stir_from_programs(void) | |
477 | { | |
478 | int c; | |
479 | double entropy, total_entropy; | |
75131bbd | 480 | unsigned char hash[SHA_DIGEST_LENGTH]; |
40f64e6f | 481 | |
482 | total_entropy = 0; | |
483 | for(c = 0; entropy_cmds[c].path != NULL; c++) { | |
484 | if (!entropy_cmds[c].badness) { | |
485 | /* Hash output from command */ | |
486 | entropy = hash_command_output(&entropy_cmds[c], | |
487 | hash); | |
488 | ||
489 | /* Scale back estimate by command's rate */ | |
490 | entropy *= entropy_cmds[c].rate; | |
491 | ||
492 | /* Upper bound of entropy is SHA_DIGEST_LENGTH */ | |
493 | if (entropy > SHA_DIGEST_LENGTH) | |
494 | entropy = SHA_DIGEST_LENGTH; | |
495 | ||
496 | /* Stir it in */ | |
497 | RAND_add(hash, sizeof(hash), entropy); | |
498 | ||
aff51935 | 499 | debug3("Got %0.2f bytes of entropy from '%s'", |
40f64e6f | 500 | entropy, entropy_cmds[c].cmdstring); |
501 | ||
502 | total_entropy += entropy; | |
503 | ||
504 | /* Execution time should be a bit unpredictable */ | |
505 | total_entropy += stir_gettimeofday(0.05); | |
506 | total_entropy += stir_clock(0.05); | |
507 | total_entropy += stir_rusage(RUSAGE_SELF, 0.1); | |
508 | total_entropy += stir_rusage(RUSAGE_CHILDREN, 0.1); | |
509 | } else { | |
510 | debug2("Command '%s' disabled (badness %d)", | |
aff51935 | 511 | entropy_cmds[c].cmdstring, |
40f64e6f | 512 | entropy_cmds[c].badness); |
513 | ||
514 | if (entropy_cmds[c].badness > 0) | |
515 | entropy_cmds[c].badness--; | |
516 | } | |
517 | } | |
518 | ||
519 | return total_entropy; | |
46058ce2 | 520 | } |
521 | ||
522 | /* | |
523 | * prng seedfile functions | |
524 | */ | |
525 | int | |
40f64e6f | 526 | prng_check_seedfile(char *filename) |
527 | { | |
46058ce2 | 528 | struct stat st; |
529 | ||
40f64e6f | 530 | /* |
aff51935 | 531 | * XXX raceable: eg replace seed between this stat and subsequent |
532 | * open. Not such a problem because we don't really trust the | |
40f64e6f | 533 | * seed file anyway. |
534 | * XXX: use secure path checking as elsewhere in OpenSSH | |
535 | */ | |
46058ce2 | 536 | if (lstat(filename, &st) == -1) { |
537 | /* Give up on hard errors */ | |
538 | if (errno != ENOENT) | |
40f64e6f | 539 | debug("WARNING: Couldn't stat random seed file " |
540 | "\"%.100s\": %s", filename, strerror(errno)); | |
541 | return 0; | |
46058ce2 | 542 | } |
543 | ||
544 | /* regular file? */ | |
545 | if (!S_ISREG(st.st_mode)) | |
40f64e6f | 546 | fatal("PRNG seedfile %.100s is not a regular file", |
547 | filename); | |
46058ce2 | 548 | |
549 | /* mode 0600, owned by root or the current user? */ | |
550 | if (((st.st_mode & 0177) != 0) || !(st.st_uid == getuid())) { | |
40f64e6f | 551 | debug("WARNING: PRNG seedfile %.100s must be mode 0600, " |
7be625e1 | 552 | "owned by uid %li", filename, (long int)getuid()); |
40f64e6f | 553 | return 0; |
46058ce2 | 554 | } |
555 | ||
40f64e6f | 556 | return 1; |
46058ce2 | 557 | } |
558 | ||
559 | void | |
40f64e6f | 560 | prng_write_seedfile(void) |
561 | { | |
a418076b | 562 | int fd, save_errno; |
75131bbd | 563 | unsigned char seed[SEED_FILE_SIZE]; |
a418076b | 564 | char filename[MAXPATHLEN], tmpseed[MAXPATHLEN]; |
46058ce2 | 565 | struct passwd *pw; |
a418076b | 566 | mode_t old_umask; |
46058ce2 | 567 | |
568 | pw = getpwuid(getuid()); | |
569 | if (pw == NULL) | |
40f64e6f | 570 | fatal("Couldn't get password entry for current user " |
7be625e1 | 571 | "(%li): %s", (long int)getuid(), strerror(errno)); |
46058ce2 | 572 | |
573 | /* Try to ensure that the parent directory is there */ | |
574 | snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir, | |
40f64e6f | 575 | _PATH_SSH_USER_DIR); |
46058ce2 | 576 | mkdir(filename, 0700); |
577 | ||
578 | snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir, | |
40f64e6f | 579 | SSH_PRNG_SEED_FILE); |
46058ce2 | 580 | |
a418076b | 581 | strlcpy(tmpseed, filename, sizeof(tmpseed)); |
582 | if (strlcat(tmpseed, ".XXXXXXXXXX", sizeof(tmpseed)) >= | |
583 | sizeof(tmpseed)) | |
584 | fatal("PRNG seed filename too long"); | |
46058ce2 | 585 | |
d8eb5247 | 586 | if (RAND_bytes(seed, sizeof(seed)) <= 0) |
9e3191db | 587 | fatal("PRNG seed extraction failed"); |
46058ce2 | 588 | |
589 | /* Don't care if the seed doesn't exist */ | |
590 | prng_check_seedfile(filename); | |
591 | ||
a418076b | 592 | old_umask = umask(0177); |
593 | ||
594 | if ((fd = mkstemp(tmpseed)) == -1) { | |
595 | debug("WARNING: couldn't make temporary PRNG seedfile %.100s " | |
596 | "(%.100s)", tmpseed, strerror(errno)); | |
46058ce2 | 597 | } else { |
a418076b | 598 | debug("writing PRNG seed to file %.100s", tmpseed); |
599 | if (atomicio(vwrite, fd, &seed, sizeof(seed)) < sizeof(seed)) { | |
600 | save_errno = errno; | |
601 | close(fd); | |
602 | unlink(tmpseed); | |
40f64e6f | 603 | fatal("problem writing PRNG seedfile %.100s " |
a418076b | 604 | "(%.100s)", filename, strerror(save_errno)); |
605 | } | |
46058ce2 | 606 | close(fd); |
a418076b | 607 | debug("moving temporary PRNG seed to file %.100s", filename); |
608 | if (rename(tmpseed, filename) == -1) { | |
609 | save_errno = errno; | |
610 | unlink(tmpseed); | |
611 | fatal("problem renaming PRNG seedfile from %.100s " | |
d1cf9a87 | 612 | "to %.100s (%.100s)", tmpseed, filename, |
a418076b | 613 | strerror(save_errno)); |
614 | } | |
46058ce2 | 615 | } |
a418076b | 616 | umask(old_umask); |
46058ce2 | 617 | } |
618 | ||
619 | void | |
40f64e6f | 620 | prng_read_seedfile(void) |
621 | { | |
46058ce2 | 622 | int fd; |
40f64e6f | 623 | char seed[SEED_FILE_SIZE], filename[MAXPATHLEN]; |
46058ce2 | 624 | struct passwd *pw; |
625 | ||
626 | pw = getpwuid(getuid()); | |
627 | if (pw == NULL) | |
40f64e6f | 628 | fatal("Couldn't get password entry for current user " |
7be625e1 | 629 | "(%li): %s", (long int)getuid(), strerror(errno)); |
46058ce2 | 630 | |
631 | snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir, | |
632 | SSH_PRNG_SEED_FILE); | |
633 | ||
634 | debug("loading PRNG seed from file %.100s", filename); | |
635 | ||
636 | if (!prng_check_seedfile(filename)) { | |
40f64e6f | 637 | verbose("Random seed file not found or invalid, ignoring."); |
46058ce2 | 638 | return; |
639 | } | |
640 | ||
641 | /* open the file and read in the seed */ | |
642 | fd = open(filename, O_RDONLY); | |
643 | if (fd == -1) | |
40f64e6f | 644 | fatal("could not open PRNG seedfile %.100s (%.100s)", |
645 | filename, strerror(errno)); | |
46058ce2 | 646 | |
40f64e6f | 647 | if (atomicio(read, fd, &seed, sizeof(seed)) < sizeof(seed)) { |
648 | verbose("invalid or short read from PRNG seedfile " | |
649 | "%.100s - ignoring", filename); | |
46058ce2 | 650 | memset(seed, '\0', sizeof(seed)); |
651 | } | |
652 | close(fd); | |
653 | ||
654 | /* stir in the seed, with estimated entropy zero */ | |
655 | RAND_add(&seed, sizeof(seed), 0.0); | |
656 | } | |
657 | ||
658 | ||
659 | /* | |
660 | * entropy command initialisation functions | |
661 | */ | |
662 | int | |
663 | prng_read_commands(char *cmdfilename) | |
664 | { | |
40f64e6f | 665 | char cmd[SEED_FILE_SIZE], *cp, line[1024], path[SEED_FILE_SIZE]; |
46058ce2 | 666 | double est; |
40f64e6f | 667 | entropy_cmd_t *entcmd; |
668 | FILE *f; | |
669 | int cur_cmd, linenum, num_cmds, arg; | |
46058ce2 | 670 | |
40f64e6f | 671 | if ((f = fopen(cmdfilename, "r")) == NULL) { |
46058ce2 | 672 | fatal("couldn't read entropy commands file %.100s: %.100s", |
673 | cmdfilename, strerror(errno)); | |
674 | } | |
675 | ||
40f64e6f | 676 | num_cmds = 64; |
01d35895 | 677 | entcmd = xcalloc(num_cmds, sizeof(entropy_cmd_t)); |
46058ce2 | 678 | |
679 | /* Read in file */ | |
40f64e6f | 680 | cur_cmd = linenum = 0; |
46058ce2 | 681 | while (fgets(line, sizeof(line), f)) { |
46058ce2 | 682 | linenum++; |
683 | ||
40f64e6f | 684 | /* Skip leading whitespace, blank lines and comments */ |
46058ce2 | 685 | cp = line + strspn(line, WHITESPACE); |
686 | if ((*cp == 0) || (*cp == '#')) | |
687 | continue; /* done with this line */ | |
688 | ||
40f64e6f | 689 | /* |
aff51935 | 690 | * The first non-whitespace char should be a double quote |
40f64e6f | 691 | * delimiting the commandline |
692 | */ | |
46058ce2 | 693 | if (*cp != '"') { |
40f64e6f | 694 | error("bad entropy command, %.100s line %d", |
695 | cmdfilename, linenum); | |
46058ce2 | 696 | continue; |
697 | } | |
698 | ||
40f64e6f | 699 | /* |
700 | * First token, command args (incl. argv[0]) in double | |
701 | * quotes | |
702 | */ | |
46058ce2 | 703 | cp = strtok(cp, "\""); |
704 | if (cp == NULL) { | |
40f64e6f | 705 | error("missing or bad command string, %.100s " |
706 | "line %d -- ignored", cmdfilename, linenum); | |
46058ce2 | 707 | continue; |
708 | } | |
709 | strlcpy(cmd, cp, sizeof(cmd)); | |
710 | ||
40f64e6f | 711 | /* Second token, full command path */ |
46058ce2 | 712 | if ((cp = strtok(NULL, WHITESPACE)) == NULL) { |
40f64e6f | 713 | error("missing command path, %.100s " |
714 | "line %d -- ignored", cmdfilename, linenum); | |
46058ce2 | 715 | continue; |
716 | } | |
717 | ||
40f64e6f | 718 | /* Did configure mark this as dead? */ |
46058ce2 | 719 | if (strncmp("undef", cp, 5) == 0) |
720 | continue; | |
721 | ||
722 | strlcpy(path, cp, sizeof(path)); | |
723 | ||
40f64e6f | 724 | /* Third token, entropy rate estimate for this command */ |
46058ce2 | 725 | if ((cp = strtok(NULL, WHITESPACE)) == NULL) { |
40f64e6f | 726 | error("missing entropy estimate, %.100s " |
727 | "line %d -- ignored", cmdfilename, linenum); | |
46058ce2 | 728 | continue; |
729 | } | |
40f64e6f | 730 | est = strtod(cp, NULL); |
46058ce2 | 731 | |
732 | /* end of line */ | |
733 | if ((cp = strtok(NULL, WHITESPACE)) != NULL) { | |
40f64e6f | 734 | error("garbage at end of line %d in %.100s " |
735 | "-- ignored", linenum, cmdfilename); | |
46058ce2 | 736 | continue; |
737 | } | |
738 | ||
739 | /* save the command for debug messages */ | |
740 | entcmd[cur_cmd].cmdstring = xstrdup(cmd); | |
741 | ||
742 | /* split the command args */ | |
743 | cp = strtok(cmd, WHITESPACE); | |
744 | arg = 0; | |
46058ce2 | 745 | do { |
40f64e6f | 746 | entcmd[cur_cmd].args[arg] = xstrdup(cp); |
46058ce2 | 747 | arg++; |
40f64e6f | 748 | } while(arg < NUM_ARGS && (cp = strtok(NULL, WHITESPACE))); |
46058ce2 | 749 | |
750 | if (strtok(NULL, WHITESPACE)) | |
40f64e6f | 751 | error("ignored extra commands (max %d), %.100s " |
752 | "line %d", NUM_ARGS, cmdfilename, linenum); | |
46058ce2 | 753 | |
754 | /* Copy the command path and rate estimate */ | |
755 | entcmd[cur_cmd].path = xstrdup(path); | |
756 | entcmd[cur_cmd].rate = est; | |
757 | ||
758 | /* Initialise other values */ | |
759 | entcmd[cur_cmd].sticky_badness = 1; | |
760 | ||
761 | cur_cmd++; | |
762 | ||
40f64e6f | 763 | /* |
764 | * If we've filled the array, reallocate it twice the size | |
aff51935 | 765 | * Do this now because even if this we're on the last |
40f64e6f | 766 | * command we need another slot to mark the last entry |
767 | */ | |
46058ce2 | 768 | if (cur_cmd == num_cmds) { |
769 | num_cmds *= 2; | |
c5d10563 | 770 | entcmd = xrealloc(entcmd, num_cmds, |
40f64e6f | 771 | sizeof(entropy_cmd_t)); |
46058ce2 | 772 | } |
773 | } | |
774 | ||
775 | /* zero the last entry */ | |
40f64e6f | 776 | memset(&entcmd[cur_cmd], '\0', sizeof(entropy_cmd_t)); |
46058ce2 | 777 | |
778 | /* trim to size */ | |
c5d10563 | 779 | entropy_cmds = xrealloc(entcmd, (cur_cmd + 1), |
40f64e6f | 780 | sizeof(entropy_cmd_t)); |
46058ce2 | 781 | |
40f64e6f | 782 | debug("Loaded %d entropy commands from %.100s", cur_cmd, |
783 | cmdfilename); | |
46058ce2 | 784 | |
40f64e6f | 785 | return cur_cmd < MIN_ENTROPY_SOURCES ? -1 : 0; |
46058ce2 | 786 | } |
787 | ||
f6e6303d | 788 | void |
789 | usage(void) | |
790 | { | |
791 | fprintf(stderr, "Usage: %s [options]\n", __progname); | |
792 | fprintf(stderr, " -v Verbose; display verbose debugging messages.\n"); | |
793 | fprintf(stderr, " Multiple -v increases verbosity.\n"); | |
96b0de7d | 794 | fprintf(stderr, " -x Force output in hexadecimal (for debugging)\n"); |
f6e6303d | 795 | fprintf(stderr, " -X Force output in binary\n"); |
796 | fprintf(stderr, " -b bytes Number of bytes to output (default %d)\n", | |
797 | OUTPUT_SEED_SIZE); | |
798 | } | |
799 | ||
aff51935 | 800 | int |
46058ce2 | 801 | main(int argc, char **argv) |
802 | { | |
f6e6303d | 803 | unsigned char *buf; |
804 | int ret, ch, debug_level, output_hex, bytes; | |
805 | extern char *optarg; | |
806 | LogLevel ll; | |
46058ce2 | 807 | |
fda04d7d | 808 | __progname = ssh_get_progname(argv[0]); |
46058ce2 | 809 | log_init(argv[0], SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_USER, 1); |
810 | ||
f6e6303d | 811 | ll = SYSLOG_LEVEL_INFO; |
812 | debug_level = output_hex = 0; | |
813 | bytes = OUTPUT_SEED_SIZE; | |
814 | ||
815 | /* Don't write binary data to a tty, unless we are forced to */ | |
816 | if (isatty(STDOUT_FILENO)) | |
817 | output_hex = 1; | |
b6453d99 | 818 | |
f6e6303d | 819 | while ((ch = getopt(argc, argv, "vxXhb:")) != -1) { |
820 | switch (ch) { | |
821 | case 'v': | |
822 | if (debug_level < 3) | |
823 | ll = SYSLOG_LEVEL_DEBUG1 + debug_level++; | |
824 | break; | |
825 | case 'x': | |
826 | output_hex = 1; | |
827 | break; | |
828 | case 'X': | |
829 | output_hex = 0; | |
830 | break; | |
831 | case 'b': | |
832 | if ((bytes = atoi(optarg)) <= 0) | |
833 | fatal("Invalid number of output bytes"); | |
834 | break; | |
835 | case 'h': | |
836 | usage(); | |
837 | exit(0); | |
838 | default: | |
839 | error("Invalid commandline option"); | |
840 | usage(); | |
841 | } | |
842 | } | |
843 | ||
844 | log_init(argv[0], ll, SYSLOG_FACILITY_USER, 1); | |
b6453d99 | 845 | |
40f64e6f | 846 | #ifdef USE_SEED_FILES |
847 | prng_read_seedfile(); | |
848 | #endif | |
849 | ||
f6e6303d | 850 | buf = xmalloc(bytes); |
851 | ||
40f64e6f | 852 | /* |
853 | * Seed the RNG from wherever we can | |
854 | */ | |
b6453d99 | 855 | |
40f64e6f | 856 | /* Take whatever is on the stack, but don't credit it */ |
f6e6303d | 857 | RAND_add(buf, bytes, 0); |
40f64e6f | 858 | |
aff51935 | 859 | debug("Seeded RNG with %i bytes from system calls", |
40f64e6f | 860 | (int)stir_from_system()); |
861 | ||
1e111f05 | 862 | /* try prngd, fall back to commands if prngd fails or not configured */ |
863 | if (seed_from_prngd(buf, bytes) == 0) { | |
864 | RAND_add(buf, bytes, bytes); | |
865 | } else { | |
866 | /* Read in collection commands */ | |
867 | if (prng_read_commands(SSH_PRNG_COMMAND_FILE) == -1) | |
868 | fatal("PRNG initialisation failed -- exiting."); | |
869 | debug("Seeded RNG with %i bytes from programs", | |
870 | (int)stir_from_programs()); | |
871 | } | |
40f64e6f | 872 | |
873 | #ifdef USE_SEED_FILES | |
874 | prng_write_seedfile(); | |
875 | #endif | |
876 | ||
877 | /* | |
878 | * Write the seed to stdout | |
879 | */ | |
46058ce2 | 880 | |
881 | if (!RAND_status()) | |
882 | fatal("Not enough entropy in RNG"); | |
883 | ||
d8eb5247 | 884 | if (RAND_bytes(buf, bytes) <= 0) |
885 | fatal("Couldn't extract entropy from PRNG"); | |
46058ce2 | 886 | |
f6e6303d | 887 | if (output_hex) { |
888 | for(ret = 0; ret < bytes; ret++) | |
889 | printf("%02x", (unsigned char)(buf[ret])); | |
890 | printf("\n"); | |
891 | } else | |
d72f7b79 | 892 | ret = atomicio(vwrite, STDOUT_FILENO, buf, bytes); |
b6453d99 | 893 | |
f6e6303d | 894 | memset(buf, '\0', bytes); |
895 | xfree(buf); | |
b6453d99 | 896 | |
f6e6303d | 897 | return ret == bytes ? 0 : 1; |
46058ce2 | 898 | } |
e005a96c | 899 | |
900 | /* | |
901 | * We may attempt to re-seed during mkstemp if we are using the one in the | |
759c7b91 | 902 | * compat library (via mkstemp -> _gettemp -> arc4random -> seed_rng) so we |
903 | * need our own seed_rng(). We must also check that we have enough entropy. | |
e005a96c | 904 | */ |
905 | void | |
906 | seed_rng(void) | |
907 | { | |
908 | if (!RAND_status()) | |
909 | fatal("Not enough entropy in RNG"); | |
910 | } |