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1/*
2 * Copyright (c) 2000 Damien Miller. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 * 3. All advertising materials mentioning features or use of this software
13 * must display the following acknowledgement:
14 * This product includes software developed by Markus Friedl.
15 * 4. The name of the author may not be used to endorse or promote products
16 * derived from this software without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
19 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
20 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
21 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
22 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
23 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
24 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
25 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
27 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 */
29
30#include "includes.h"
31
32#include "ssh.h"
33#include "xmalloc.h"
34
35#include <openssl/rand.h>
36#include <openssl/sha.h>
37
38/* SunOS 4.4.4 needs this */
39#ifdef HAVE_FLOATINGPOINT_H
40# include <floatingpoint.h>
41#endif /* HAVE_FLOATINGPOINT_H */
42
43RCSID("$Id: entropy.c,v 1.18 2000/07/15 04:59:15 djm Exp $");
44
45#ifndef offsetof
46# define offsetof(type, member) ((size_t) &((type *)0)->member)
47#endif
48
49/* Print lots of detail */
50/* #define DEBUG_ENTROPY */
51
52/* Number of times to pass through command list gathering entropy */
53#define NUM_ENTROPY_RUNS 1
54
55/* Scale entropy estimates back by this amount on subsequent runs */
56#define SCALE_PER_RUN 10.0
57
58/* Minimum number of commands to be considered valid */
59#define MIN_ENTROPY_SOURCES 16
60
61#define WHITESPACE " \t\n"
62
63#ifndef RUSAGE_SELF
64# define RUSAGE_SELF 0
65#endif
66#ifndef RUSAGE_CHILDREN
67# define RUSAGE_CHILDREN 0
68#endif
69
70#if defined(EGD_SOCKET) || defined(RANDOM_POOL)
71
72#ifdef EGD_SOCKET
73/* Collect entropy from EGD */
74int get_random_bytes(unsigned char *buf, int len)
75{
76 int fd;
77 char msg[2];
78 struct sockaddr_un addr;
79 int addr_len;
80
81 /* Sanity checks */
82 if (sizeof(EGD_SOCKET) > sizeof(addr.sun_path))
83 fatal("Random pool path is too long");
84 if (len > 255)
85 fatal("Too many bytes to read from EGD");
86
87 memset(&addr, '\0', sizeof(addr));
88 addr.sun_family = AF_UNIX;
89 strlcpy(addr.sun_path, EGD_SOCKET, sizeof(addr.sun_path));
90 addr_len = offsetof(struct sockaddr_un, sun_path) + sizeof(EGD_SOCKET);
91
92 fd = socket(AF_UNIX, SOCK_STREAM, 0);
93 if (fd == -1) {
94 error("Couldn't create AF_UNIX socket: %s", strerror(errno));
95 return(0);
96 }
97
98 if (connect(fd, (struct sockaddr*)&addr, addr_len) == -1) {
99 error("Couldn't connect to EGD socket \"%s\": %s",
100 addr.sun_path, strerror(errno));
101 close(fd);
102 return(0);
103 }
104
105 /* Send blocking read request to EGD */
106 msg[0] = 0x02;
107 msg[1] = len;
108
109 if (atomicio(write, fd, msg, sizeof(msg)) != sizeof(msg)) {
110 error("Couldn't write to EGD socket \"%s\": %s",
111 EGD_SOCKET, strerror(errno));
112 close(fd);
113 return(0);
114 }
115
116 if (atomicio(read, fd, buf, len) != len) {
117 error("Couldn't read from EGD socket \"%s\": %s",
118 EGD_SOCKET, strerror(errno));
119 close(fd);
120 return(0);
121 }
122
123 close(fd);
124
125 return(1);
126}
127#else /* !EGD_SOCKET */
128#ifdef RANDOM_POOL
129/* Collect entropy from /dev/urandom or pipe */
130int get_random_bytes(unsigned char *buf, int len)
131{
132 int random_pool;
133
134 random_pool = open(RANDOM_POOL, O_RDONLY);
135 if (random_pool == -1) {
136 error("Couldn't open random pool \"%s\": %s",
137 RANDOM_POOL, strerror(errno));
138 return(0);
139 }
140
141 if (atomicio(read, random_pool, buf, len) != len) {
142 error("Couldn't read from random pool \"%s\": %s",
143 RANDOM_POOL, strerror(errno));
144 close(random_pool);
145 return(0);
146 }
147
148 close(random_pool);
149
150 return(1);
151}
152#endif /* RANDOM_POOL */
153#endif /* EGD_SOCKET */
154
155/*
156 * Seed OpenSSL's random number pool from Kernel random number generator
157 * or EGD
158 */
159void
160seed_rng(void)
161{
162 char buf[32];
163
164 debug("Seeding random number generator");
165
166 if (!get_random_bytes(buf, sizeof(buf))) {
167 if (!RAND_status())
168 fatal("Entropy collection failed and entropy exhausted");
169 } else {
170 RAND_add(buf, sizeof(buf), sizeof(buf));
171 }
172
173 memset(buf, '\0', sizeof(buf));
174}
175
176/* No-op */
177void init_rng(void) {}
178
179#else /* defined(EGD_SOCKET) || defined(RANDOM_POOL) */
180
181/*
182 * FIXME: proper entropy estimations. All current values are guesses
183 * FIXME: (ATL) do estimates at compile time?
184 * FIXME: More entropy sources
185 */
186
187/* slow command timeouts (all in milliseconds) */
188/* static int entropy_timeout_default = ENTROPY_TIMEOUT_MSEC; */
189static int entropy_timeout_current = ENTROPY_TIMEOUT_MSEC;
190
191static int prng_seed_saved = 0;
192static int prng_initialised = 0;
193uid_t original_uid;
194
195typedef struct
196{
197 /* Proportion of data that is entropy */
198 double rate;
199 /* Counter goes positive if this command times out */
200 unsigned int badness;
201 /* Increases by factor of two each timeout */
202 unsigned int sticky_badness;
203 /* Path to executable */
204 char *path;
205 /* argv to pass to executable */
206 char *args[5];
207 /* full command string (debug) */
208 char *cmdstring;
209} entropy_source_t;
210
211double stir_from_system(void);
212double stir_from_programs(void);
213double stir_gettimeofday(double entropy_estimate);
214double stir_clock(double entropy_estimate);
215double stir_rusage(int who, double entropy_estimate);
216double hash_output_from_command(entropy_source_t *src, char *hash);
217
218/* this is initialised from a file, by prng_read_commands() */
219entropy_source_t *entropy_sources = NULL;
220
221double
222stir_from_system(void)
223{
224 double total_entropy_estimate;
225 long int i;
226
227 total_entropy_estimate = 0;
228
229 i = getpid();
230 RAND_add(&i, sizeof(i), 0.5);
231 total_entropy_estimate += 0.1;
232
233 i = getppid();
234 RAND_add(&i, sizeof(i), 0.5);
235 total_entropy_estimate += 0.1;
236
237 i = getuid();
238 RAND_add(&i, sizeof(i), 0.0);
239 i = getgid();
240 RAND_add(&i, sizeof(i), 0.0);
241
242 total_entropy_estimate += stir_gettimeofday(1.0);
243 total_entropy_estimate += stir_clock(0.5);
244 total_entropy_estimate += stir_rusage(RUSAGE_SELF, 2.0);
245
246 return(total_entropy_estimate);
247}
248
249double
250stir_from_programs(void)
251{
252 int i;
253 int c;
254 double entropy_estimate;
255 double total_entropy_estimate;
256 char hash[SHA_DIGEST_LENGTH];
257
258 total_entropy_estimate = 0;
259 for(i = 0; i < NUM_ENTROPY_RUNS; i++) {
260 c = 0;
261 while (entropy_sources[c].path != NULL) {
262
263 if (!entropy_sources[c].badness) {
264 /* Hash output from command */
265 entropy_estimate = hash_output_from_command(&entropy_sources[c], hash);
266
267 /* Scale back entropy estimate according to command's rate */
268 entropy_estimate *= entropy_sources[c].rate;
269
270 /* Upper bound of entropy estimate is SHA_DIGEST_LENGTH */
271 if (entropy_estimate > SHA_DIGEST_LENGTH)
272 entropy_estimate = SHA_DIGEST_LENGTH;
273
274 /* Scale back estimates for subsequent passes through list */
275 entropy_estimate /= SCALE_PER_RUN * (i + 1.0);
276
277 /* Stir it in */
278 RAND_add(hash, sizeof(hash), entropy_estimate);
279
280#ifdef DEBUG_ENTROPY
281 debug("Got %0.2f bytes of entropy from '%s'", entropy_estimate,
282 entropy_sources[c].cmdstring);
283#endif
284
285 total_entropy_estimate += entropy_estimate;
286
287 /* Execution times should be a little unpredictable */
288 total_entropy_estimate += stir_gettimeofday(0.05);
289 total_entropy_estimate += stir_clock(0.05);
290 total_entropy_estimate += stir_rusage(RUSAGE_SELF, 0.1);
291 total_entropy_estimate += stir_rusage(RUSAGE_CHILDREN, 0.1);
292 } else {
293#ifdef DEBUG_ENTROPY
294 debug("Command '%s' disabled (badness %d)",
295 entropy_sources[c].cmdstring, entropy_sources[c].badness);
296#endif
297
298 if (entropy_sources[c].badness > 0)
299 entropy_sources[c].badness--;
300 }
301
302 c++;
303 }
304 }
305
306 return(total_entropy_estimate);
307}
308
309double
310stir_gettimeofday(double entropy_estimate)
311{
312 struct timeval tv;
313
314 if (gettimeofday(&tv, NULL) == -1)
315 fatal("Couldn't gettimeofday: %s", strerror(errno));
316
317 RAND_add(&tv, sizeof(tv), entropy_estimate);
318
319 return(entropy_estimate);
320}
321
322double
323stir_clock(double entropy_estimate)
324{
325#ifdef HAVE_CLOCK
326 clock_t c;
327
328 c = clock();
329 RAND_add(&c, sizeof(c), entropy_estimate);
330
331 return(entropy_estimate);
332#else /* _HAVE_CLOCK */
333 return(0);
334#endif /* _HAVE_CLOCK */
335}
336
337double
338stir_rusage(int who, double entropy_estimate)
339{
340#ifdef HAVE_GETRUSAGE
341 struct rusage ru;
342
343 if (getrusage(who, &ru) == -1)
344 return(0);
345
346 RAND_add(&ru, sizeof(ru), entropy_estimate);
347
348 return(entropy_estimate);
349#else /* _HAVE_GETRUSAGE */
350 return(0);
351#endif /* _HAVE_GETRUSAGE */
352}
353
354
355static
356int
357_get_timeval_msec_difference(struct timeval *t1, struct timeval *t2) {
358 int secdiff, usecdiff;
359
360 secdiff = t2->tv_sec - t1->tv_sec;
361 usecdiff = (secdiff*1000000) + (t2->tv_usec - t1->tv_usec);
362 return (int)(usecdiff / 1000);
363}
364
365double
366hash_output_from_command(entropy_source_t *src, char *hash)
367{
368 static int devnull = -1;
369 int p[2];
370 fd_set rdset;
371 int cmd_eof = 0, error_abort = 0;
372 struct timeval tv_start, tv_current;
373 int msec_elapsed = 0;
374 pid_t pid;
375 int status;
376 char buf[16384];
377 int bytes_read;
378 int total_bytes_read;
379 SHA_CTX sha;
380
381 if (devnull == -1) {
382 devnull = open("/dev/null", O_RDWR);
383 if (devnull == -1)
384 fatal("Couldn't open /dev/null: %s", strerror(errno));
385 }
386
387 if (pipe(p) == -1)
388 fatal("Couldn't open pipe: %s", strerror(errno));
389
390 (void)gettimeofday(&tv_start, NULL); /* record start time */
391
392 switch (pid = fork()) {
393 case -1: /* Error */
394 close(p[0]);
395 close(p[1]);
396 fatal("Couldn't fork: %s", strerror(errno));
397 /* NOTREACHED */
398 case 0: /* Child */
399 dup2(devnull, STDIN_FILENO);
400 dup2(p[1], STDOUT_FILENO);
401 dup2(p[1], STDERR_FILENO);
402 close(p[0]);
403 close(p[1]);
404 close(devnull);
405
406 setuid(original_uid);
407 execv(src->path, (char**)(src->args));
408 debug("(child) Couldn't exec '%s': %s", src->cmdstring,
409 strerror(errno));
410 _exit(-1);
411 default: /* Parent */
412 break;
413 }
414
415 RAND_add(&pid, sizeof(&pid), 0.0);
416
417 close(p[1]);
418
419 /* Hash output from child */
420 SHA1_Init(&sha);
421 total_bytes_read = 0;
422
423 while (!error_abort && !cmd_eof) {
424 int ret;
425 struct timeval tv;
426 int msec_remaining;
427
428 (void) gettimeofday(&tv_current, 0);
429 msec_elapsed = _get_timeval_msec_difference(&tv_start, &tv_current);
430 if (msec_elapsed >= entropy_timeout_current) {
431 error_abort=1;
432 continue;
433 }
434 msec_remaining = entropy_timeout_current - msec_elapsed;
435
436 FD_ZERO(&rdset);
437 FD_SET(p[0], &rdset);
438 tv.tv_sec = msec_remaining / 1000;
439 tv.tv_usec = (msec_remaining % 1000) * 1000;
440
441 ret = select(p[0]+1, &rdset, NULL, NULL, &tv);
442
443 RAND_add(&tv, sizeof(tv), 0.0);
444
445 switch (ret) {
446 case 0:
447 /* timer expired */
448 error_abort = 1;
449 break;
450 case 1:
451 /* command input */
452 bytes_read = read(p[0], buf, sizeof(buf));
453 RAND_add(&bytes_read, sizeof(&bytes_read), 0.0);
454 if (bytes_read == -1) {
455 error_abort = 1;
456 break;
457 } else if (bytes_read) {
458 SHA1_Update(&sha, buf, bytes_read);
459 total_bytes_read += bytes_read;
460 } else {
461 cmd_eof = 1;
462 }
463 break;
464 case -1:
465 default:
466 /* error */
467 debug("Command '%s': select() failed: %s", src->cmdstring,
468 strerror(errno));
469 error_abort = 1;
470 break;
471 }
472 }
473
474 SHA1_Final(hash, &sha);
475
476 close(p[0]);
477
478#ifdef DEBUG_ENTROPY
479 debug("Time elapsed: %d msec", msec_elapsed);
480#endif
481
482 if (waitpid(pid, &status, 0) == -1) {
483 debug("Couldn't wait for child '%s' completion: %s", src->cmdstring,
484 strerror(errno));
485 return(0.0);
486 }
487
488 RAND_add(&status, sizeof(&status), 0.0);
489
490 if (error_abort) {
491 /* closing p[0] on timeout causes the entropy command to
492 * SIGPIPE. Take whatever output we got, and mark this command
493 * as slow */
494 debug("Command '%s' timed out", src->cmdstring);
495 src->sticky_badness *= 2;
496 src->badness = src->sticky_badness;
497 return(total_bytes_read);
498 }
499
500 if (WIFEXITED(status)) {
501 if (WEXITSTATUS(status)==0) {
502 return(total_bytes_read);
503 } else {
504 debug("Command '%s' exit status was %d", src->cmdstring,
505 WEXITSTATUS(status));
506 src->badness = src->sticky_badness = 128;
507 return (0.0);
508 }
509 } else if (WIFSIGNALED(status)) {
510 debug("Command '%s' returned on uncaught signal %d !", src->cmdstring,
511 status);
512 src->badness = src->sticky_badness = 128;
513 return(0.0);
514 } else
515 return(0.0);
516}
517
518/*
519 * prng seedfile functions
520 */
521int
522prng_check_seedfile(char *filename) {
523
524 struct stat st;
525
526 /* FIXME raceable: eg replace seed between this stat and subsequent open */
527 /* Not such a problem because we don't trust the seed file anyway */
528 if (lstat(filename, &st) == -1) {
529 /* Fail on hard errors */
530 if (errno != ENOENT)
531 fatal("Couldn't stat random seed file \"%s\": %s", filename,
532 strerror(errno));
533
534 return(0);
535 }
536
537 /* regular file? */
538 if (!S_ISREG(st.st_mode))
539 fatal("PRNG seedfile %.100s is not a regular file", filename);
540
541 /* mode 0600, owned by root or the current user? */
542 if (((st.st_mode & 0177) != 0) || !(st.st_uid == original_uid))
543 fatal("PRNG seedfile %.100s must be mode 0600, owned by uid %d",
544 filename, getuid());
545
546 return(1);
547}
548
549void
550prng_write_seedfile(void) {
551 int fd;
552 char seed[1024];
553 char filename[1024];
554 struct passwd *pw;
555
556 /* Don't bother if we have already saved a seed */
557 if (prng_seed_saved)
558 return;
559
560 setuid(original_uid);
561
562 prng_seed_saved = 1;
563
564 pw = getpwuid(original_uid);
565 if (pw == NULL)
566 fatal("Couldn't get password entry for current user (%i): %s",
567 original_uid, strerror(errno));
568
569 /* Try to ensure that the parent directory is there */
570 snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir,
571 SSH_USER_DIR);
572 mkdir(filename, 0700);
573
574 snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir,
575 SSH_PRNG_SEED_FILE);
576
577 debug("writing PRNG seed to file %.100s", filename);
578
579 RAND_bytes(seed, sizeof(seed));
580
581 /* Don't care if the seed doesn't exist */
582 prng_check_seedfile(filename);
583
584 if ((fd = open(filename, O_WRONLY|O_TRUNC|O_CREAT, 0600)) == -1)
585 fatal("couldn't access PRNG seedfile %.100s (%.100s)", filename,
586 strerror(errno));
587
588 if (atomicio(write, fd, &seed, sizeof(seed)) != sizeof(seed))
589 fatal("problem writing PRNG seedfile %.100s (%.100s)", filename,
590 strerror(errno));
591
592 close(fd);
593}
594
595void
596prng_read_seedfile(void) {
597 int fd;
598 char seed[1024];
599 char filename[1024];
600 struct passwd *pw;
601
602 pw = getpwuid(original_uid);
603 if (pw == NULL)
604 fatal("Couldn't get password entry for current user (%i): %s",
605 original_uid, strerror(errno));
606
607 snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir,
608 SSH_PRNG_SEED_FILE);
609
610 debug("loading PRNG seed from file %.100s", filename);
611
612 if (!prng_check_seedfile(filename)) {
613 verbose("Random seed file not found, creating new");
614 prng_write_seedfile();
615
616 /* Reseed immediatly */
617 (void)stir_from_system();
618 (void)stir_from_programs();
619 return;
620 }
621
622 /* open the file and read in the seed */
623 fd = open(filename, O_RDONLY);
624 if (fd == -1)
625 fatal("could not open PRNG seedfile %.100s (%.100s)", filename,
626 strerror(errno));
627
628 if (atomicio(read, fd, &seed, sizeof(seed)) != sizeof(seed)) {
629 verbose("invalid or short read from PRNG seedfile %.100s - ignoring",
630 filename);
631 memset(seed, '\0', sizeof(seed));
632 }
633 close(fd);
634
635 /* stir in the seed, with estimated entropy zero */
636 RAND_add(&seed, sizeof(seed), 0.0);
637}
638
639
640/*
641 * entropy command initialisation functions
642 */
643int
644prng_read_commands(char *cmdfilename)
645{
646 FILE *f;
647 char *cp;
648 char line[1024];
649 char cmd[1024];
650 char path[256];
651 int linenum;
652 int num_cmds = 64;
653 int cur_cmd = 0;
654 double est;
655 entropy_source_t *entcmd;
656
657 f = fopen(cmdfilename, "r");
658 if (!f) {
659 fatal("couldn't read entropy commands file %.100s: %.100s",
660 cmdfilename, strerror(errno));
661 }
662
663 entcmd = (entropy_source_t *)xmalloc(num_cmds * sizeof(entropy_source_t));
664 memset(entcmd, '\0', num_cmds * sizeof(entropy_source_t));
665
666 /* Read in file */
667 linenum = 0;
668 while (fgets(line, sizeof(line), f)) {
669 int arg;
670 char *argv;
671
672 linenum++;
673
674 /* skip leading whitespace, test for blank line or comment */
675 cp = line + strspn(line, WHITESPACE);
676 if ((*cp == 0) || (*cp == '#'))
677 continue; /* done with this line */
678
679 /* First non-whitespace char should be double quote delimiting */
680 /* commandline */
681 if (*cp != '"') {
682 error("bad entropy command, %.100s line %d", cmdfilename,
683 linenum);
684 continue;
685 }
686
687 /* first token, command args (incl. argv[0]) in double quotes */
688 cp = strtok(cp, "\"");
689 if (cp == NULL) {
690 error("missing or bad command string, %.100s line %d -- ignored",
691 cmdfilename, linenum);
692 continue;
693 }
694 strlcpy(cmd, cp, sizeof(cmd));
695
696 /* second token, full command path */
697 if ((cp = strtok(NULL, WHITESPACE)) == NULL) {
698 error("missing command path, %.100s line %d -- ignored",
699 cmdfilename, linenum);
700 continue;
701 }
702
703 /* did configure mark this as dead? */
704 if (strncmp("undef", cp, 5) == 0)
705 continue;
706
707 strlcpy(path, cp, sizeof(path));
708
709 /* third token, entropy rate estimate for this command */
710 if ((cp = strtok(NULL, WHITESPACE)) == NULL) {
711 error("missing entropy estimate, %.100s line %d -- ignored",
712 cmdfilename, linenum);
713 continue;
714 }
715 est = strtod(cp, &argv);
716
717 /* end of line */
718 if ((cp = strtok(NULL, WHITESPACE)) != NULL) {
719 error("garbage at end of line %d in %.100s -- ignored", linenum,
720 cmdfilename);
721 continue;
722 }
723
724 /* save the command for debug messages */
725 entcmd[cur_cmd].cmdstring = xstrdup(cmd);
726
727 /* split the command args */
728 cp = strtok(cmd, WHITESPACE);
729 arg = 0;
730 argv = NULL;
731 do {
732 char *s = (char*)xmalloc(strlen(cp) + 1);
733 strncpy(s, cp, strlen(cp) + 1);
734 entcmd[cur_cmd].args[arg] = s;
735 arg++;
736 } while ((arg < 5) && (cp = strtok(NULL, WHITESPACE)));
737
738 if (strtok(NULL, WHITESPACE))
739 error("ignored extra command elements (max 5), %.100s line %d",
740 cmdfilename, linenum);
741
742 /* Copy the command path and rate estimate */
743 entcmd[cur_cmd].path = xstrdup(path);
744 entcmd[cur_cmd].rate = est;
745
746 /* Initialise other values */
747 entcmd[cur_cmd].sticky_badness = 1;
748
749 cur_cmd++;
750
751 /* If we've filled the array, reallocate it twice the size */
752 /* Do this now because even if this we're on the last command,
753 we need another slot to mark the last entry */
754 if (cur_cmd == num_cmds) {
755 num_cmds *= 2;
756 entcmd = xrealloc(entcmd, num_cmds * sizeof(entropy_source_t));
757 }
758 }
759
760 /* zero the last entry */
761 memset(&entcmd[cur_cmd], '\0', sizeof(entropy_source_t));
762
763 /* trim to size */
764 entropy_sources = xrealloc(entcmd, (cur_cmd+1) * sizeof(entropy_source_t));
765
766 debug("Loaded %d entropy commands from %.100s", cur_cmd, cmdfilename);
767
768 return (cur_cmd >= MIN_ENTROPY_SOURCES);
769}
770
771/*
772 * Write a keyfile at exit
773 */
774void
775prng_seed_cleanup(void *junk)
776{
777 prng_write_seedfile();
778}
779
780/*
781 * Conditionally Seed OpenSSL's random number pool from
782 * syscalls and program output
783 */
784void
785seed_rng(void)
786{
787 void *old_sigchld_handler;
788
789 if (!prng_initialised)
790 fatal("RNG not initialised");
791
792 /* Make sure some other sigchld handler doesn't reap our entropy */
793 /* commands */
794 old_sigchld_handler = signal(SIGCHLD, SIG_DFL);
795
796 debug("Seeded RNG with %i bytes from programs", (int)stir_from_programs());
797 debug("Seeded RNG with %i bytes from system calls", (int)stir_from_system());
798
799 if (!RAND_status())
800 fatal("Not enough entropy in RNG");
801
802 signal(SIGCHLD, old_sigchld_handler);
803
804 if (!RAND_status())
805 fatal("Couldn't initialise builtin random number generator -- exiting.");
806}
807
808void init_rng(void)
809{
810 original_uid = getuid();
811
812 /* Read in collection commands */
813 if (!prng_read_commands(SSH_PRNG_COMMAND_FILE))
814 fatal("PRNG initialisation failed -- exiting.");
815
816 /* Set ourselves up to save a seed upon exit */
817 prng_seed_saved = 0;
818 prng_read_seedfile();
819 fatal_add_cleanup(prng_seed_cleanup, NULL);
820 atexit(prng_write_seedfile);
821
822 prng_initialised = 1;
823}
824
825#endif /* defined(EGD_SOCKET) || defined(RANDOM_POOL) */