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 <sys/types.h>
28 #include <sys/resource.h>
31 #include <sys/socket.h>
36 #include <netinet/in.h>
37 #include <arpa/inet.h>
50 #include <openssl/rand.h>
51 #include <openssl/sha.h>
52 #include <openssl/crypto.h>
54 /* SunOS 4.4.4 needs this */
55 #ifdef HAVE_FLOATINGPOINT_H
56 # include <floatingpoint.h>
57 #endif /* HAVE_FLOATINGPOINT_H */
62 #include "pathnames.h"
65 /* Number of bytes we write out */
66 #define OUTPUT_SEED_SIZE 48
68 /* Length of on-disk seedfiles */
69 #define SEED_FILE_SIZE 1024
71 /* Maximum number of command-line arguments to read from file */
74 /* Minimum number of usable commands to be considered sufficient */
75 #define MIN_ENTROPY_SOURCES 16
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"
82 /* Path to PRNG commands list (from pathnames.c) */
83 extern char *SSH_PRNG_COMMAND_FILE;
85 extern char *__progname;
87 #define WHITESPACE " \t\n"
90 # define RUSAGE_SELF 0
92 #ifndef RUSAGE_CHILDREN
93 # define RUSAGE_CHILDREN 0
96 #if !defined(PRNGD_SOCKET) && !defined(PRNGD_PORT)
97 # define USE_SEED_FILES
101 /* Proportion of data that is entropy */
103 /* Counter goes positive if this command times out */
104 unsigned int badness;
105 /* Increases by factor of two each timeout */
106 unsigned int sticky_badness;
107 /* Path to executable */
109 /* argv to pass to executable */
110 char *args[NUM_ARGS]; /* XXX: arbitrary limit */
111 /* full command string (debug) */
115 /* slow command timeouts (all in milliseconds) */
116 /* static int entropy_timeout_default = ENTROPY_TIMEOUT_MSEC; */
117 static int entropy_timeout_current = ENTROPY_TIMEOUT_MSEC;
119 /* this is initialised from a file, by prng_read_commands() */
120 static entropy_cmd_t *entropy_cmds = NULL;
123 double stir_from_system(void);
124 double stir_from_programs(void);
125 double stir_gettimeofday(double entropy_estimate);
126 double stir_clock(double entropy_estimate);
127 double stir_rusage(int who, double entropy_estimate);
128 double hash_command_output(entropy_cmd_t *src, unsigned char *hash);
129 int get_random_bytes_prngd(unsigned char *buf, int len,
130 unsigned short tcp_port, char *socket_path);
133 * Collect 'len' bytes of entropy into 'buf' from PRNGD/EGD daemon
134 * listening either on 'tcp_port', or via Unix domain socket at *
136 * Either a non-zero tcp_port or a non-null socket_path must be
138 * Returns 0 on success, -1 on error
141 get_random_bytes_prngd(unsigned char *buf, int len,
142 unsigned short tcp_port, char *socket_path)
144 int fd, addr_len, rval, errors;
146 struct sockaddr_storage addr;
147 struct sockaddr_in *addr_in = (struct sockaddr_in *)&addr;
148 struct sockaddr_un *addr_un = (struct sockaddr_un *)&addr;
152 if (socket_path == NULL && tcp_port == 0)
153 fatal("You must specify a port or a socket");
154 if (socket_path != NULL &&
155 strlen(socket_path) >= sizeof(addr_un->sun_path))
156 fatal("Random pool path is too long");
157 if (len <= 0 || len > 255)
158 fatal("Too many bytes (%d) to read from PRNGD", len);
160 memset(&addr, '\0', sizeof(addr));
163 addr_in->sin_family = AF_INET;
164 addr_in->sin_addr.s_addr = htonl(INADDR_LOOPBACK);
165 addr_in->sin_port = htons(tcp_port);
166 addr_len = sizeof(*addr_in);
168 addr_un->sun_family = AF_UNIX;
169 strlcpy(addr_un->sun_path, socket_path,
170 sizeof(addr_un->sun_path));
171 addr_len = offsetof(struct sockaddr_un, sun_path) +
172 strlen(socket_path) + 1;
175 old_sigpipe = mysignal(SIGPIPE, SIG_IGN);
180 fd = socket(addr.ss_family, SOCK_STREAM, 0);
182 error("Couldn't create socket: %s", strerror(errno));
186 if (connect(fd, (struct sockaddr*)&addr, addr_len) == -1) {
188 error("Couldn't connect to PRNGD port %d: %s",
189 tcp_port, strerror(errno));
191 error("Couldn't connect to PRNGD socket \"%s\": %s",
192 addr_un->sun_path, strerror(errno));
197 /* Send blocking read request to PRNGD */
201 if (atomicio(vwrite, fd, msg, sizeof(msg)) != sizeof(msg)) {
202 if (errno == EPIPE && errors < 10) {
207 error("Couldn't write to PRNGD socket: %s",
212 if (atomicio(read, fd, buf, len) != (size_t)len) {
213 if (errno == EPIPE && errors < 10) {
218 error("Couldn't read from PRNGD socket: %s",
225 mysignal(SIGPIPE, old_sigpipe);
232 seed_from_prngd(unsigned char *buf, size_t bytes)
235 debug("trying egd/prngd port %d", PRNGD_PORT);
236 if (get_random_bytes_prngd(buf, bytes, PRNGD_PORT, NULL) == 0)
240 debug("trying egd/prngd socket %s", PRNGD_SOCKET);
241 if (get_random_bytes_prngd(buf, bytes, 0, PRNGD_SOCKET) == 0)
248 stir_gettimeofday(double entropy_estimate)
252 if (gettimeofday(&tv, NULL) == -1)
253 fatal("Couldn't gettimeofday: %s", strerror(errno));
255 RAND_add(&tv, sizeof(tv), entropy_estimate);
257 return entropy_estimate;
261 stir_clock(double entropy_estimate)
267 RAND_add(&c, sizeof(c), entropy_estimate);
269 return entropy_estimate;
270 #else /* _HAVE_CLOCK */
272 #endif /* _HAVE_CLOCK */
276 stir_rusage(int who, double entropy_estimate)
278 #ifdef HAVE_GETRUSAGE
281 if (getrusage(who, &ru) == -1)
284 RAND_add(&ru, sizeof(ru), entropy_estimate);
286 return entropy_estimate;
287 #else /* _HAVE_GETRUSAGE */
289 #endif /* _HAVE_GETRUSAGE */
293 timeval_diff(struct timeval *t1, struct timeval *t2)
295 int secdiff, usecdiff;
297 secdiff = t2->tv_sec - t1->tv_sec;
298 usecdiff = (secdiff*1000000) + (t2->tv_usec - t1->tv_usec);
299 return (int)(usecdiff / 1000);
303 hash_command_output(entropy_cmd_t *src, unsigned char *hash)
307 int bytes_read, cmd_eof, error_abort, msec_elapsed, p[2];
308 int status, total_bytes_read;
309 static int devnull = -1;
312 struct timeval tv_start, tv_current;
314 debug3("Reading output from \'%s\'", src->cmdstring);
317 devnull = open("/dev/null", O_RDWR);
319 fatal("Couldn't open /dev/null: %s",
324 fatal("Couldn't open pipe: %s", strerror(errno));
326 (void)gettimeofday(&tv_start, NULL); /* record start time */
328 switch (pid = fork()) {
332 fatal("Couldn't fork: %s", strerror(errno));
335 dup2(devnull, STDIN_FILENO);
336 dup2(p[1], STDOUT_FILENO);
337 dup2(p[1], STDERR_FILENO);
342 execv(src->path, (char**)(src->args));
344 debug("(child) Couldn't exec '%s': %s",
345 src->cmdstring, strerror(errno));
347 default: /* Parent */
351 RAND_add(&pid, sizeof(&pid), 0.0);
355 /* Hash output from child */
358 cmd_eof = error_abort = msec_elapsed = total_bytes_read = 0;
359 while (!error_abort && !cmd_eof) {
364 (void) gettimeofday(&tv_current, 0);
365 msec_elapsed = timeval_diff(&tv_start, &tv_current);
366 if (msec_elapsed >= entropy_timeout_current) {
370 msec_remaining = entropy_timeout_current - msec_elapsed;
373 FD_SET(p[0], &rdset);
374 tv.tv_sec = msec_remaining / 1000;
375 tv.tv_usec = (msec_remaining % 1000) * 1000;
377 ret = select(p[0] + 1, &rdset, NULL, NULL, &tv);
379 RAND_add(&tv, sizeof(tv), 0.0);
390 bytes_read = read(p[0], buf, sizeof(buf));
391 } while (bytes_read == -1 && errno == EINTR);
392 RAND_add(&bytes_read, sizeof(&bytes_read), 0.0);
393 if (bytes_read == -1) {
396 } else if (bytes_read) {
397 SHA1_Update(&sha, buf, bytes_read);
398 total_bytes_read += bytes_read;
406 debug("Command '%s': select() failed: %s",
407 src->cmdstring, strerror(errno));
413 SHA1_Final(hash, &sha);
417 debug3("Time elapsed: %d msec", msec_elapsed);
419 if (waitpid(pid, &status, 0) == -1) {
420 error("Couldn't wait for child '%s' completion: %s",
421 src->cmdstring, strerror(errno));
425 RAND_add(&status, sizeof(&status), 0.0);
429 * Closing p[0] on timeout causes the entropy command to
430 * SIGPIPE. Take whatever output we got, and mark this
433 debug2("Command '%s' timed out", src->cmdstring);
434 src->sticky_badness *= 2;
435 src->badness = src->sticky_badness;
436 return total_bytes_read;
439 if (WIFEXITED(status)) {
440 if (WEXITSTATUS(status) == 0) {
441 return total_bytes_read;
443 debug2("Command '%s' exit status was %d",
444 src->cmdstring, WEXITSTATUS(status));
445 src->badness = src->sticky_badness = 128;
448 } else if (WIFSIGNALED(status)) {
449 debug2("Command '%s' returned on uncaught signal %d !",
450 src->cmdstring, status);
451 src->badness = src->sticky_badness = 128;
458 stir_from_system(void)
460 double total_entropy_estimate;
463 total_entropy_estimate = 0;
466 RAND_add(&i, sizeof(i), 0.5);
467 total_entropy_estimate += 0.1;
470 RAND_add(&i, sizeof(i), 0.5);
471 total_entropy_estimate += 0.1;
474 RAND_add(&i, sizeof(i), 0.0);
476 RAND_add(&i, sizeof(i), 0.0);
478 total_entropy_estimate += stir_gettimeofday(1.0);
479 total_entropy_estimate += stir_clock(0.5);
480 total_entropy_estimate += stir_rusage(RUSAGE_SELF, 2.0);
482 return total_entropy_estimate;
486 stir_from_programs(void)
489 double entropy, total_entropy;
490 unsigned char hash[SHA_DIGEST_LENGTH];
493 for(c = 0; entropy_cmds[c].path != NULL; c++) {
494 if (!entropy_cmds[c].badness) {
495 /* Hash output from command */
496 entropy = hash_command_output(&entropy_cmds[c],
499 /* Scale back estimate by command's rate */
500 entropy *= entropy_cmds[c].rate;
502 /* Upper bound of entropy is SHA_DIGEST_LENGTH */
503 if (entropy > SHA_DIGEST_LENGTH)
504 entropy = SHA_DIGEST_LENGTH;
507 RAND_add(hash, sizeof(hash), entropy);
509 debug3("Got %0.2f bytes of entropy from '%s'",
510 entropy, entropy_cmds[c].cmdstring);
512 total_entropy += entropy;
514 /* Execution time should be a bit unpredictable */
515 total_entropy += stir_gettimeofday(0.05);
516 total_entropy += stir_clock(0.05);
517 total_entropy += stir_rusage(RUSAGE_SELF, 0.1);
518 total_entropy += stir_rusage(RUSAGE_CHILDREN, 0.1);
520 debug2("Command '%s' disabled (badness %d)",
521 entropy_cmds[c].cmdstring,
522 entropy_cmds[c].badness);
524 if (entropy_cmds[c].badness > 0)
525 entropy_cmds[c].badness--;
529 return total_entropy;
533 * prng seedfile functions
536 prng_check_seedfile(char *filename)
541 * XXX raceable: eg replace seed between this stat and subsequent
542 * open. Not such a problem because we don't really trust the
544 * XXX: use secure path checking as elsewhere in OpenSSH
546 if (lstat(filename, &st) == -1) {
547 /* Give up on hard errors */
549 debug("WARNING: Couldn't stat random seed file "
550 "\"%.100s\": %s", filename, strerror(errno));
555 if (!S_ISREG(st.st_mode))
556 fatal("PRNG seedfile %.100s is not a regular file",
559 /* mode 0600, owned by root or the current user? */
560 if (((st.st_mode & 0177) != 0) || !(st.st_uid == getuid())) {
561 debug("WARNING: PRNG seedfile %.100s must be mode 0600, "
562 "owned by uid %li", filename, (long int)getuid());
570 prng_write_seedfile(void)
573 unsigned char seed[SEED_FILE_SIZE];
574 char filename[MAXPATHLEN], tmpseed[MAXPATHLEN];
578 pw = getpwuid(getuid());
580 fatal("Couldn't get password entry for current user "
581 "(%li): %s", (long int)getuid(), strerror(errno));
583 /* Try to ensure that the parent directory is there */
584 snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir,
586 if (mkdir(filename, 0700) < 0 && errno != EEXIST)
587 fatal("mkdir %.200s: %s", filename, strerror(errno));
589 snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir,
592 strlcpy(tmpseed, filename, sizeof(tmpseed));
593 if (strlcat(tmpseed, ".XXXXXXXXXX", sizeof(tmpseed)) >=
595 fatal("PRNG seed filename too long");
597 if (RAND_bytes(seed, sizeof(seed)) <= 0)
598 fatal("PRNG seed extraction failed");
600 /* Don't care if the seed doesn't exist */
601 prng_check_seedfile(filename);
603 old_umask = umask(0177);
605 if ((fd = mkstemp(tmpseed)) == -1) {
606 debug("WARNING: couldn't make temporary PRNG seedfile %.100s "
607 "(%.100s)", tmpseed, strerror(errno));
609 debug("writing PRNG seed to file %.100s", tmpseed);
610 if (atomicio(vwrite, fd, &seed, sizeof(seed)) < sizeof(seed)) {
614 fatal("problem writing PRNG seedfile %.100s "
615 "(%.100s)", filename, strerror(save_errno));
618 debug("moving temporary PRNG seed to file %.100s", filename);
619 if (rename(tmpseed, filename) == -1) {
622 fatal("problem renaming PRNG seedfile from %.100s "
623 "to %.100s (%.100s)", tmpseed, filename,
624 strerror(save_errno));
631 prng_read_seedfile(void)
634 char seed[SEED_FILE_SIZE], filename[MAXPATHLEN];
637 pw = getpwuid(getuid());
639 fatal("Couldn't get password entry for current user "
640 "(%li): %s", (long int)getuid(), strerror(errno));
642 snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir,
645 debug("loading PRNG seed from file %.100s", filename);
647 if (!prng_check_seedfile(filename)) {
648 verbose("Random seed file not found or invalid, ignoring.");
652 /* open the file and read in the seed */
653 fd = open(filename, O_RDONLY);
655 fatal("could not open PRNG seedfile %.100s (%.100s)",
656 filename, strerror(errno));
658 if (atomicio(read, fd, &seed, sizeof(seed)) < sizeof(seed)) {
659 verbose("invalid or short read from PRNG seedfile "
660 "%.100s - ignoring", filename);
661 memset(seed, '\0', sizeof(seed));
665 /* stir in the seed, with estimated entropy zero */
666 RAND_add(&seed, sizeof(seed), 0.0);
671 * entropy command initialisation functions
674 prng_read_commands(char *cmdfilename)
676 char cmd[SEED_FILE_SIZE], *cp, line[1024], path[SEED_FILE_SIZE];
678 entropy_cmd_t *entcmd;
680 int cur_cmd, linenum, num_cmds, arg;
682 if ((f = fopen(cmdfilename, "r")) == NULL) {
683 fatal("couldn't read entropy commands file %.100s: %.100s",
684 cmdfilename, strerror(errno));
688 entcmd = xcalloc(num_cmds, sizeof(entropy_cmd_t));
691 cur_cmd = linenum = 0;
692 while (fgets(line, sizeof(line), f)) {
695 /* Skip leading whitespace, blank lines and comments */
696 cp = line + strspn(line, WHITESPACE);
697 if ((*cp == 0) || (*cp == '#'))
698 continue; /* done with this line */
701 * The first non-whitespace char should be a double quote
702 * delimiting the commandline
705 error("bad entropy command, %.100s line %d",
706 cmdfilename, linenum);
711 * First token, command args (incl. argv[0]) in double
714 cp = strtok(cp, "\"");
716 error("missing or bad command string, %.100s "
717 "line %d -- ignored", cmdfilename, linenum);
720 strlcpy(cmd, cp, sizeof(cmd));
722 /* Second token, full command path */
723 if ((cp = strtok(NULL, WHITESPACE)) == NULL) {
724 error("missing command path, %.100s "
725 "line %d -- ignored", cmdfilename, linenum);
729 /* Did configure mark this as dead? */
730 if (strncmp("undef", cp, 5) == 0)
733 strlcpy(path, cp, sizeof(path));
735 /* Third token, entropy rate estimate for this command */
736 if ((cp = strtok(NULL, WHITESPACE)) == NULL) {
737 error("missing entropy estimate, %.100s "
738 "line %d -- ignored", cmdfilename, linenum);
741 est = strtod(cp, NULL);
744 if ((cp = strtok(NULL, WHITESPACE)) != NULL) {
745 error("garbage at end of line %d in %.100s "
746 "-- ignored", linenum, cmdfilename);
750 /* save the command for debug messages */
751 entcmd[cur_cmd].cmdstring = xstrdup(cmd);
753 /* split the command args */
754 cp = strtok(cmd, WHITESPACE);
757 entcmd[cur_cmd].args[arg] = xstrdup(cp);
759 } while(arg < NUM_ARGS && (cp = strtok(NULL, WHITESPACE)));
761 if (strtok(NULL, WHITESPACE))
762 error("ignored extra commands (max %d), %.100s "
763 "line %d", NUM_ARGS, cmdfilename, linenum);
765 /* Copy the command path and rate estimate */
766 entcmd[cur_cmd].path = xstrdup(path);
767 entcmd[cur_cmd].rate = est;
769 /* Initialise other values */
770 entcmd[cur_cmd].sticky_badness = 1;
775 * If we've filled the array, reallocate it twice the size
776 * Do this now because even if this we're on the last
777 * command we need another slot to mark the last entry
779 if (cur_cmd == num_cmds) {
781 entcmd = xrealloc(entcmd, num_cmds,
782 sizeof(entropy_cmd_t));
786 /* zero the last entry */
787 memset(&entcmd[cur_cmd], '\0', sizeof(entropy_cmd_t));
790 entropy_cmds = xrealloc(entcmd, (cur_cmd + 1),
791 sizeof(entropy_cmd_t));
793 debug("Loaded %d entropy commands from %.100s", cur_cmd,
797 return cur_cmd < MIN_ENTROPY_SOURCES ? -1 : 0;
803 fprintf(stderr, "Usage: %s [options]\n", __progname);
804 fprintf(stderr, " -v Verbose; display verbose debugging messages.\n");
805 fprintf(stderr, " Multiple -v increases verbosity.\n");
806 fprintf(stderr, " -x Force output in hexadecimal (for debugging)\n");
807 fprintf(stderr, " -X Force output in binary\n");
808 fprintf(stderr, " -b bytes Number of bytes to output (default %d)\n",
813 main(int argc, char **argv)
816 int ret, ch, debug_level, output_hex, bytes;
820 __progname = ssh_get_progname(argv[0]);
822 log_init(argv[0], SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_USER, 1);
824 ll = SYSLOG_LEVEL_INFO;
825 debug_level = output_hex = 0;
826 bytes = OUTPUT_SEED_SIZE;
828 /* Don't write binary data to a tty, unless we are forced to */
829 if (isatty(STDOUT_FILENO))
832 while ((ch = getopt(argc, argv, "vxXhb:")) != -1) {
836 ll = SYSLOG_LEVEL_DEBUG1 + debug_level++;
845 if ((bytes = atoi(optarg)) <= 0)
846 fatal("Invalid number of output bytes");
852 error("Invalid commandline option");
857 log_init(argv[0], ll, SYSLOG_FACILITY_USER, 1);
859 #ifdef USE_SEED_FILES
860 prng_read_seedfile();
863 buf = xmalloc(bytes);
866 * Seed the RNG from wherever we can
869 /* Take whatever is on the stack, but don't credit it */
870 RAND_add(buf, bytes, 0);
872 debug("Seeded RNG with %i bytes from system calls",
873 (int)stir_from_system());
875 /* try prngd, fall back to commands if prngd fails or not configured */
876 if (seed_from_prngd(buf, bytes) == 0) {
877 RAND_add(buf, bytes, bytes);
879 /* Read in collection commands */
880 if (prng_read_commands(SSH_PRNG_COMMAND_FILE) == -1)
881 fatal("PRNG initialisation failed -- exiting.");
882 debug("Seeded RNG with %i bytes from programs",
883 (int)stir_from_programs());
886 #ifdef USE_SEED_FILES
887 prng_write_seedfile();
891 * Write the seed to stdout
895 fatal("Not enough entropy in RNG");
897 if (RAND_bytes(buf, bytes) <= 0)
898 fatal("Couldn't extract entropy from PRNG");
901 for(ret = 0; ret < bytes; ret++)
902 printf("%02x", (unsigned char)(buf[ret]));
905 ret = atomicio(vwrite, STDOUT_FILENO, buf, bytes);
907 memset(buf, '\0', bytes);
910 return ret == bytes ? 0 : 1;
914 * We may attempt to re-seed during mkstemp if we are using the one in the
915 * compat library (via mkstemp -> _gettemp -> arc4random -> seed_rng) so we
916 * need our own seed_rng(). We must also check that we have enough entropy.
922 fatal("Not enough entropy in RNG");