2 * Copyright (c) 2001-2002 Damien Miller. All rights reserved.
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
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.
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.
27 #include <openssl/rand.h>
28 #include <openssl/sha.h>
29 #include <openssl/crypto.h>
31 /* SunOS 4.4.4 needs this */
32 #ifdef HAVE_FLOATINGPOINT_H
33 # include <floatingpoint.h>
34 #endif /* HAVE_FLOATINGPOINT_H */
39 #include "pathnames.h"
44 /* Number of bytes we write out */
45 #define OUTPUT_SEED_SIZE 48
47 /* Length of on-disk seedfiles */
48 #define SEED_FILE_SIZE 1024
50 /* Maximum number of command-line arguments to read from file */
53 /* Minimum number of usable commands to be considered sufficient */
54 #define MIN_ENTROPY_SOURCES 16
56 /* Path to on-disk seed file (relative to user's home directory */
57 #ifndef SSH_PRNG_SEED_FILE
58 # define SSH_PRNG_SEED_FILE _PATH_SSH_USER_DIR"/prng_seed"
61 /* Path to PRNG commands list */
62 #ifndef SSH_PRNG_COMMAND_FILE
63 # define SSH_PRNG_COMMAND_FILE SSHDIR "/ssh_prng_cmds"
66 #ifdef HAVE___PROGNAME
67 extern char *__progname;
72 #define WHITESPACE " \t\n"
75 # define RUSAGE_SELF 0
77 #ifndef RUSAGE_CHILDREN
78 # define RUSAGE_CHILDREN 0
81 #if !defined(PRNGD_SOCKET) && !defined(PRNGD_PORT)
82 # define USE_SEED_FILES
86 /* Proportion of data that is entropy */
88 /* Counter goes positive if this command times out */
90 /* Increases by factor of two each timeout */
91 unsigned int sticky_badness;
92 /* Path to executable */
94 /* argv to pass to executable */
95 char *args[NUM_ARGS]; /* XXX: arbitrary limit */
96 /* full command string (debug) */
100 /* slow command timeouts (all in milliseconds) */
101 /* static int entropy_timeout_default = ENTROPY_TIMEOUT_MSEC; */
102 static int entropy_timeout_current = ENTROPY_TIMEOUT_MSEC;
104 /* this is initialised from a file, by prng_read_commands() */
105 static entropy_cmd_t *entropy_cmds = NULL;
108 double stir_from_system(void);
109 double stir_from_programs(void);
110 double stir_gettimeofday(double entropy_estimate);
111 double stir_clock(double entropy_estimate);
112 double stir_rusage(int who, double entropy_estimate);
113 double hash_command_output(entropy_cmd_t *src, unsigned char *hash);
114 int get_random_bytes_prngd(unsigned char *buf, int len,
115 unsigned short tcp_port, char *socket_path);
118 * Collect 'len' bytes of entropy into 'buf' from PRNGD/EGD daemon
119 * listening either on 'tcp_port', or via Unix domain socket at *
121 * Either a non-zero tcp_port or a non-null socket_path must be
123 * Returns 0 on success, -1 on error
126 get_random_bytes_prngd(unsigned char *buf, int len,
127 unsigned short tcp_port, char *socket_path)
129 int fd, addr_len, rval, errors;
131 struct sockaddr_storage addr;
132 struct sockaddr_in *addr_in = (struct sockaddr_in *)&addr;
133 struct sockaddr_un *addr_un = (struct sockaddr_un *)&addr;
137 if (socket_path == NULL && tcp_port == 0)
138 fatal("You must specify a port or a socket");
139 if (socket_path != NULL &&
140 strlen(socket_path) >= sizeof(addr_un->sun_path))
141 fatal("Random pool path is too long");
143 fatal("Too many bytes to read from PRNGD");
145 memset(&addr, '\0', sizeof(addr));
148 addr_in->sin_family = AF_INET;
149 addr_in->sin_addr.s_addr = htonl(INADDR_LOOPBACK);
150 addr_in->sin_port = htons(tcp_port);
151 addr_len = sizeof(*addr_in);
153 addr_un->sun_family = AF_UNIX;
154 strlcpy(addr_un->sun_path, socket_path,
155 sizeof(addr_un->sun_path));
156 addr_len = offsetof(struct sockaddr_un, sun_path) +
157 strlen(socket_path) + 1;
160 old_sigpipe = mysignal(SIGPIPE, SIG_IGN);
165 fd = socket(addr.ss_family, SOCK_STREAM, 0);
167 error("Couldn't create socket: %s", strerror(errno));
171 if (connect(fd, (struct sockaddr*)&addr, addr_len) == -1) {
173 error("Couldn't connect to PRNGD port %d: %s",
174 tcp_port, strerror(errno));
176 error("Couldn't connect to PRNGD socket \"%s\": %s",
177 addr_un->sun_path, strerror(errno));
182 /* Send blocking read request to PRNGD */
186 if (atomicio(vwrite, fd, msg, sizeof(msg)) != sizeof(msg)) {
187 if (errno == EPIPE && errors < 10) {
192 error("Couldn't write to PRNGD socket: %s",
197 if (atomicio(read, fd, buf, len) != len) {
198 if (errno == EPIPE && errors < 10) {
203 error("Couldn't read from PRNGD socket: %s",
210 mysignal(SIGPIPE, old_sigpipe);
217 stir_gettimeofday(double entropy_estimate)
221 if (gettimeofday(&tv, NULL) == -1)
222 fatal("Couldn't gettimeofday: %s", strerror(errno));
224 RAND_add(&tv, sizeof(tv), entropy_estimate);
226 return entropy_estimate;
230 stir_clock(double entropy_estimate)
236 RAND_add(&c, sizeof(c), entropy_estimate);
238 return entropy_estimate;
239 #else /* _HAVE_CLOCK */
241 #endif /* _HAVE_CLOCK */
245 stir_rusage(int who, double entropy_estimate)
247 #ifdef HAVE_GETRUSAGE
250 if (getrusage(who, &ru) == -1)
253 RAND_add(&ru, sizeof(ru), entropy_estimate);
255 return entropy_estimate;
256 #else /* _HAVE_GETRUSAGE */
258 #endif /* _HAVE_GETRUSAGE */
262 timeval_diff(struct timeval *t1, struct timeval *t2)
264 int secdiff, usecdiff;
266 secdiff = t2->tv_sec - t1->tv_sec;
267 usecdiff = (secdiff*1000000) + (t2->tv_usec - t1->tv_usec);
268 return (int)(usecdiff / 1000);
272 hash_command_output(entropy_cmd_t *src, unsigned char *hash)
276 int bytes_read, cmd_eof, error_abort, msec_elapsed, p[2];
277 int status, total_bytes_read;
278 static int devnull = -1;
281 struct timeval tv_start, tv_current;
283 debug3("Reading output from \'%s\'", src->cmdstring);
286 devnull = open("/dev/null", O_RDWR);
288 fatal("Couldn't open /dev/null: %s",
293 fatal("Couldn't open pipe: %s", strerror(errno));
295 (void)gettimeofday(&tv_start, NULL); /* record start time */
297 switch (pid = fork()) {
301 fatal("Couldn't fork: %s", strerror(errno));
304 dup2(devnull, STDIN_FILENO);
305 dup2(p[1], STDOUT_FILENO);
306 dup2(p[1], STDERR_FILENO);
311 execv(src->path, (char**)(src->args));
313 debug("(child) Couldn't exec '%s': %s",
314 src->cmdstring, strerror(errno));
316 default: /* Parent */
320 RAND_add(&pid, sizeof(&pid), 0.0);
324 /* Hash output from child */
327 cmd_eof = error_abort = msec_elapsed = total_bytes_read = 0;
328 while (!error_abort && !cmd_eof) {
333 (void) gettimeofday(&tv_current, 0);
334 msec_elapsed = timeval_diff(&tv_start, &tv_current);
335 if (msec_elapsed >= entropy_timeout_current) {
339 msec_remaining = entropy_timeout_current - msec_elapsed;
342 FD_SET(p[0], &rdset);
343 tv.tv_sec = msec_remaining / 1000;
344 tv.tv_usec = (msec_remaining % 1000) * 1000;
346 ret = select(p[0] + 1, &rdset, NULL, NULL, &tv);
348 RAND_add(&tv, sizeof(tv), 0.0);
359 bytes_read = read(p[0], buf, sizeof(buf));
360 } while (bytes_read == -1 && errno == EINTR);
361 RAND_add(&bytes_read, sizeof(&bytes_read), 0.0);
362 if (bytes_read == -1) {
365 } else if (bytes_read) {
366 SHA1_Update(&sha, buf, bytes_read);
367 total_bytes_read += bytes_read;
375 debug("Command '%s': select() failed: %s",
376 src->cmdstring, strerror(errno));
382 SHA1_Final(hash, &sha);
386 debug3("Time elapsed: %d msec", msec_elapsed);
388 if (waitpid(pid, &status, 0) == -1) {
389 error("Couldn't wait for child '%s' completion: %s",
390 src->cmdstring, strerror(errno));
394 RAND_add(&status, sizeof(&status), 0.0);
398 * Closing p[0] on timeout causes the entropy command to
399 * SIGPIPE. Take whatever output we got, and mark this
402 debug2("Command '%s' timed out", src->cmdstring);
403 src->sticky_badness *= 2;
404 src->badness = src->sticky_badness;
405 return total_bytes_read;
408 if (WIFEXITED(status)) {
409 if (WEXITSTATUS(status) == 0) {
410 return total_bytes_read;
412 debug2("Command '%s' exit status was %d",
413 src->cmdstring, WEXITSTATUS(status));
414 src->badness = src->sticky_badness = 128;
417 } else if (WIFSIGNALED(status)) {
418 debug2("Command '%s' returned on uncaught signal %d !",
419 src->cmdstring, status);
420 src->badness = src->sticky_badness = 128;
427 stir_from_system(void)
429 double total_entropy_estimate;
432 total_entropy_estimate = 0;
435 RAND_add(&i, sizeof(i), 0.5);
436 total_entropy_estimate += 0.1;
439 RAND_add(&i, sizeof(i), 0.5);
440 total_entropy_estimate += 0.1;
443 RAND_add(&i, sizeof(i), 0.0);
445 RAND_add(&i, sizeof(i), 0.0);
447 total_entropy_estimate += stir_gettimeofday(1.0);
448 total_entropy_estimate += stir_clock(0.5);
449 total_entropy_estimate += stir_rusage(RUSAGE_SELF, 2.0);
451 return total_entropy_estimate;
455 stir_from_programs(void)
458 double entropy, total_entropy;
459 unsigned char hash[SHA_DIGEST_LENGTH];
462 for(c = 0; entropy_cmds[c].path != NULL; c++) {
463 if (!entropy_cmds[c].badness) {
464 /* Hash output from command */
465 entropy = hash_command_output(&entropy_cmds[c],
468 /* Scale back estimate by command's rate */
469 entropy *= entropy_cmds[c].rate;
471 /* Upper bound of entropy is SHA_DIGEST_LENGTH */
472 if (entropy > SHA_DIGEST_LENGTH)
473 entropy = SHA_DIGEST_LENGTH;
476 RAND_add(hash, sizeof(hash), entropy);
478 debug3("Got %0.2f bytes of entropy from '%s'",
479 entropy, entropy_cmds[c].cmdstring);
481 total_entropy += entropy;
483 /* Execution time should be a bit unpredictable */
484 total_entropy += stir_gettimeofday(0.05);
485 total_entropy += stir_clock(0.05);
486 total_entropy += stir_rusage(RUSAGE_SELF, 0.1);
487 total_entropy += stir_rusage(RUSAGE_CHILDREN, 0.1);
489 debug2("Command '%s' disabled (badness %d)",
490 entropy_cmds[c].cmdstring,
491 entropy_cmds[c].badness);
493 if (entropy_cmds[c].badness > 0)
494 entropy_cmds[c].badness--;
498 return total_entropy;
502 * prng seedfile functions
505 prng_check_seedfile(char *filename)
510 * XXX raceable: eg replace seed between this stat and subsequent
511 * open. Not such a problem because we don't really trust the
513 * XXX: use secure path checking as elsewhere in OpenSSH
515 if (lstat(filename, &st) == -1) {
516 /* Give up on hard errors */
518 debug("WARNING: Couldn't stat random seed file "
519 "\"%.100s\": %s", filename, strerror(errno));
524 if (!S_ISREG(st.st_mode))
525 fatal("PRNG seedfile %.100s is not a regular file",
528 /* mode 0600, owned by root or the current user? */
529 if (((st.st_mode & 0177) != 0) || !(st.st_uid == getuid())) {
530 debug("WARNING: PRNG seedfile %.100s must be mode 0600, "
531 "owned by uid %li", filename, (long int)getuid());
539 prng_write_seedfile(void)
542 unsigned char seed[SEED_FILE_SIZE];
543 char filename[MAXPATHLEN];
546 pw = getpwuid(getuid());
548 fatal("Couldn't get password entry for current user "
549 "(%li): %s", (long int)getuid(), strerror(errno));
551 /* Try to ensure that the parent directory is there */
552 snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir,
554 mkdir(filename, 0700);
556 snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir,
559 debug("writing PRNG seed to file %.100s", filename);
561 if (RAND_bytes(seed, sizeof(seed)) <= 0)
562 fatal("PRNG seed extraction failed");
564 /* Don't care if the seed doesn't exist */
565 prng_check_seedfile(filename);
567 if ((fd = open(filename, O_WRONLY|O_TRUNC|O_CREAT, 0600)) == -1) {
568 debug("WARNING: couldn't access PRNG seedfile %.100s "
569 "(%.100s)", filename, strerror(errno));
571 if (atomicio(vwrite, fd, &seed, sizeof(seed)) < sizeof(seed))
572 fatal("problem writing PRNG seedfile %.100s "
573 "(%.100s)", filename, strerror(errno));
579 prng_read_seedfile(void)
582 char seed[SEED_FILE_SIZE], filename[MAXPATHLEN];
585 pw = getpwuid(getuid());
587 fatal("Couldn't get password entry for current user "
588 "(%li): %s", (long int)getuid(), strerror(errno));
590 snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir,
593 debug("loading PRNG seed from file %.100s", filename);
595 if (!prng_check_seedfile(filename)) {
596 verbose("Random seed file not found or invalid, ignoring.");
600 /* open the file and read in the seed */
601 fd = open(filename, O_RDONLY);
603 fatal("could not open PRNG seedfile %.100s (%.100s)",
604 filename, strerror(errno));
606 if (atomicio(read, fd, &seed, sizeof(seed)) < sizeof(seed)) {
607 verbose("invalid or short read from PRNG seedfile "
608 "%.100s - ignoring", filename);
609 memset(seed, '\0', sizeof(seed));
613 /* stir in the seed, with estimated entropy zero */
614 RAND_add(&seed, sizeof(seed), 0.0);
619 * entropy command initialisation functions
622 prng_read_commands(char *cmdfilename)
624 char cmd[SEED_FILE_SIZE], *cp, line[1024], path[SEED_FILE_SIZE];
626 entropy_cmd_t *entcmd;
628 int cur_cmd, linenum, num_cmds, arg;
630 if ((f = fopen(cmdfilename, "r")) == NULL) {
631 fatal("couldn't read entropy commands file %.100s: %.100s",
632 cmdfilename, strerror(errno));
636 entcmd = xmalloc(num_cmds * sizeof(entropy_cmd_t));
637 memset(entcmd, '\0', num_cmds * sizeof(entropy_cmd_t));
640 cur_cmd = linenum = 0;
641 while (fgets(line, sizeof(line), f)) {
644 /* Skip leading whitespace, blank lines and comments */
645 cp = line + strspn(line, WHITESPACE);
646 if ((*cp == 0) || (*cp == '#'))
647 continue; /* done with this line */
650 * The first non-whitespace char should be a double quote
651 * delimiting the commandline
654 error("bad entropy command, %.100s line %d",
655 cmdfilename, linenum);
660 * First token, command args (incl. argv[0]) in double
663 cp = strtok(cp, "\"");
665 error("missing or bad command string, %.100s "
666 "line %d -- ignored", cmdfilename, linenum);
669 strlcpy(cmd, cp, sizeof(cmd));
671 /* Second token, full command path */
672 if ((cp = strtok(NULL, WHITESPACE)) == NULL) {
673 error("missing command path, %.100s "
674 "line %d -- ignored", cmdfilename, linenum);
678 /* Did configure mark this as dead? */
679 if (strncmp("undef", cp, 5) == 0)
682 strlcpy(path, cp, sizeof(path));
684 /* Third token, entropy rate estimate for this command */
685 if ((cp = strtok(NULL, WHITESPACE)) == NULL) {
686 error("missing entropy estimate, %.100s "
687 "line %d -- ignored", cmdfilename, linenum);
690 est = strtod(cp, NULL);
693 if ((cp = strtok(NULL, WHITESPACE)) != NULL) {
694 error("garbage at end of line %d in %.100s "
695 "-- ignored", linenum, cmdfilename);
699 /* save the command for debug messages */
700 entcmd[cur_cmd].cmdstring = xstrdup(cmd);
702 /* split the command args */
703 cp = strtok(cmd, WHITESPACE);
706 entcmd[cur_cmd].args[arg] = xstrdup(cp);
708 } while(arg < NUM_ARGS && (cp = strtok(NULL, WHITESPACE)));
710 if (strtok(NULL, WHITESPACE))
711 error("ignored extra commands (max %d), %.100s "
712 "line %d", NUM_ARGS, cmdfilename, linenum);
714 /* Copy the command path and rate estimate */
715 entcmd[cur_cmd].path = xstrdup(path);
716 entcmd[cur_cmd].rate = est;
718 /* Initialise other values */
719 entcmd[cur_cmd].sticky_badness = 1;
724 * If we've filled the array, reallocate it twice the size
725 * Do this now because even if this we're on the last
726 * command we need another slot to mark the last entry
728 if (cur_cmd == num_cmds) {
730 entcmd = xrealloc(entcmd, num_cmds *
731 sizeof(entropy_cmd_t));
735 /* zero the last entry */
736 memset(&entcmd[cur_cmd], '\0', sizeof(entropy_cmd_t));
739 entropy_cmds = xrealloc(entcmd, (cur_cmd + 1) *
740 sizeof(entropy_cmd_t));
742 debug("Loaded %d entropy commands from %.100s", cur_cmd,
745 return cur_cmd < MIN_ENTROPY_SOURCES ? -1 : 0;
751 fprintf(stderr, "Usage: %s [options]\n", __progname);
752 fprintf(stderr, " -v Verbose; display verbose debugging messages.\n");
753 fprintf(stderr, " Multiple -v increases verbosity.\n");
754 fprintf(stderr, " -x Force output in hexidecimal (for debugging)\n");
755 fprintf(stderr, " -X Force output in binary\n");
756 fprintf(stderr, " -b bytes Number of bytes to output (default %d)\n",
761 main(int argc, char **argv)
764 int ret, ch, debug_level, output_hex, bytes;
768 __progname = ssh_get_progname(argv[0]);
769 log_init(argv[0], SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_USER, 1);
771 ll = SYSLOG_LEVEL_INFO;
772 debug_level = output_hex = 0;
773 bytes = OUTPUT_SEED_SIZE;
775 /* Don't write binary data to a tty, unless we are forced to */
776 if (isatty(STDOUT_FILENO))
779 while ((ch = getopt(argc, argv, "vxXhb:")) != -1) {
783 ll = SYSLOG_LEVEL_DEBUG1 + debug_level++;
792 if ((bytes = atoi(optarg)) <= 0)
793 fatal("Invalid number of output bytes");
799 error("Invalid commandline option");
804 log_init(argv[0], ll, SYSLOG_FACILITY_USER, 1);
806 #ifdef USE_SEED_FILES
807 prng_read_seedfile();
810 buf = xmalloc(bytes);
813 * Seed the RNG from wherever we can
816 /* Take whatever is on the stack, but don't credit it */
817 RAND_add(buf, bytes, 0);
819 debug("Seeded RNG with %i bytes from system calls",
820 (int)stir_from_system());
823 if (get_random_bytes_prngd(buf, bytes, PRNGD_PORT, NULL) == -1)
824 fatal("Entropy collection failed");
825 RAND_add(buf, bytes, bytes);
826 #elif defined(PRNGD_SOCKET)
827 if (get_random_bytes_prngd(buf, bytes, 0, PRNGD_SOCKET) == -1)
828 fatal("Entropy collection failed");
829 RAND_add(buf, bytes, bytes);
831 /* Read in collection commands */
832 if (prng_read_commands(SSH_PRNG_COMMAND_FILE) == -1)
833 fatal("PRNG initialisation failed -- exiting.");
834 debug("Seeded RNG with %i bytes from programs",
835 (int)stir_from_programs());
838 #ifdef USE_SEED_FILES
839 prng_write_seedfile();
843 * Write the seed to stdout
847 fatal("Not enough entropy in RNG");
849 if (RAND_bytes(buf, bytes) <= 0)
850 fatal("Couldn't extract entropy from PRNG");
853 for(ret = 0; ret < bytes; ret++)
854 printf("%02x", (unsigned char)(buf[ret]));
857 ret = atomicio(vwrite, STDOUT_FILENO, buf, bytes);
859 memset(buf, '\0', bytes);
862 return ret == bytes ? 0 : 1;