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"
42
RCSID("$Id: ssh-rand-helper.c,v 1.16 2003/11/21 12:56:47 djm Exp $");
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;
73
# define offsetof(type, member) ((size_t) &((type *)0)->member)
76
#define WHITESPACE " \t\n"
79
# define RUSAGE_SELF 0
81
#ifndef RUSAGE_CHILDREN
82
# define RUSAGE_CHILDREN 0
85
#if !defined(PRNGD_SOCKET) && !defined(PRNGD_PORT)
86
# define USE_SEED_FILES
90
/* Proportion of data that is entropy */
92
/* Counter goes positive if this command times out */
94
/* Increases by factor of two each timeout */
95
unsigned int sticky_badness;
96
/* Path to executable */
98
/* argv to pass to executable */
99
char *args[NUM_ARGS]; /* XXX: arbitrary limit */
100
/* full command string (debug) */
104
/* slow command timeouts (all in milliseconds) */
105
/* static int entropy_timeout_default = ENTROPY_TIMEOUT_MSEC; */
106
static int entropy_timeout_current = ENTROPY_TIMEOUT_MSEC;
108
/* this is initialised from a file, by prng_read_commands() */
109
static entropy_cmd_t *entropy_cmds = NULL;
112
double stir_from_system(void);
113
double stir_from_programs(void);
114
double stir_gettimeofday(double entropy_estimate);
115
double stir_clock(double entropy_estimate);
116
double stir_rusage(int who, double entropy_estimate);
117
double hash_command_output(entropy_cmd_t *src, unsigned char *hash);
118
int get_random_bytes_prngd(unsigned char *buf, int len,
119
unsigned short tcp_port, char *socket_path);
122
* Collect 'len' bytes of entropy into 'buf' from PRNGD/EGD daemon
123
* listening either on 'tcp_port', or via Unix domain socket at *
125
* Either a non-zero tcp_port or a non-null socket_path must be
127
* Returns 0 on success, -1 on error
130
get_random_bytes_prngd(unsigned char *buf, int len,
131
unsigned short tcp_port, char *socket_path)
133
int fd, addr_len, rval, errors;
135
struct sockaddr_storage addr;
136
struct sockaddr_in *addr_in = (struct sockaddr_in *)&addr;
137
struct sockaddr_un *addr_un = (struct sockaddr_un *)&addr;
141
if (socket_path == NULL && tcp_port == 0)
142
fatal("You must specify a port or a socket");
143
if (socket_path != NULL &&
144
strlen(socket_path) >= sizeof(addr_un->sun_path))
145
fatal("Random pool path is too long");
147
fatal("Too many bytes to read from PRNGD");
149
memset(&addr, '\0', sizeof(addr));
152
addr_in->sin_family = AF_INET;
153
addr_in->sin_addr.s_addr = htonl(INADDR_LOOPBACK);
154
addr_in->sin_port = htons(tcp_port);
155
addr_len = sizeof(*addr_in);
157
addr_un->sun_family = AF_UNIX;
158
strlcpy(addr_un->sun_path, socket_path,
159
sizeof(addr_un->sun_path));
160
addr_len = offsetof(struct sockaddr_un, sun_path) +
161
strlen(socket_path) + 1;
164
old_sigpipe = mysignal(SIGPIPE, SIG_IGN);
169
fd = socket(addr.ss_family, SOCK_STREAM, 0);
171
error("Couldn't create socket: %s", strerror(errno));
175
if (connect(fd, (struct sockaddr*)&addr, addr_len) == -1) {
177
error("Couldn't connect to PRNGD port %d: %s",
178
tcp_port, strerror(errno));
180
error("Couldn't connect to PRNGD socket \"%s\": %s",
181
addr_un->sun_path, strerror(errno));
186
/* Send blocking read request to PRNGD */
190
if (atomicio(vwrite, fd, msg, sizeof(msg)) != sizeof(msg)) {
191
if (errno == EPIPE && errors < 10) {
196
error("Couldn't write to PRNGD socket: %s",
201
if (atomicio(read, fd, buf, len) != len) {
202
if (errno == EPIPE && errors < 10) {
207
error("Couldn't read from PRNGD socket: %s",
214
mysignal(SIGPIPE, old_sigpipe);
221
stir_gettimeofday(double entropy_estimate)
225
if (gettimeofday(&tv, NULL) == -1)
226
fatal("Couldn't gettimeofday: %s", strerror(errno));
228
RAND_add(&tv, sizeof(tv), entropy_estimate);
230
return entropy_estimate;
234
stir_clock(double entropy_estimate)
240
RAND_add(&c, sizeof(c), entropy_estimate);
242
return entropy_estimate;
243
#else /* _HAVE_CLOCK */
245
#endif /* _HAVE_CLOCK */
249
stir_rusage(int who, double entropy_estimate)
251
#ifdef HAVE_GETRUSAGE
254
if (getrusage(who, &ru) == -1)
257
RAND_add(&ru, sizeof(ru), entropy_estimate);
259
return entropy_estimate;
260
#else /* _HAVE_GETRUSAGE */
262
#endif /* _HAVE_GETRUSAGE */
266
timeval_diff(struct timeval *t1, struct timeval *t2)
268
int secdiff, usecdiff;
270
secdiff = t2->tv_sec - t1->tv_sec;
271
usecdiff = (secdiff*1000000) + (t2->tv_usec - t1->tv_usec);
272
return (int)(usecdiff / 1000);
276
hash_command_output(entropy_cmd_t *src, unsigned char *hash)
280
int bytes_read, cmd_eof, error_abort, msec_elapsed, p[2];
281
int status, total_bytes_read;
282
static int devnull = -1;
285
struct timeval tv_start, tv_current;
287
debug3("Reading output from \'%s\'", src->cmdstring);
290
devnull = open("/dev/null", O_RDWR);
292
fatal("Couldn't open /dev/null: %s",
297
fatal("Couldn't open pipe: %s", strerror(errno));
299
(void)gettimeofday(&tv_start, NULL); /* record start time */
301
switch (pid = fork()) {
305
fatal("Couldn't fork: %s", strerror(errno));
308
dup2(devnull, STDIN_FILENO);
309
dup2(p[1], STDOUT_FILENO);
310
dup2(p[1], STDERR_FILENO);
315
execv(src->path, (char**)(src->args));
317
debug("(child) Couldn't exec '%s': %s",
318
src->cmdstring, strerror(errno));
320
default: /* Parent */
324
RAND_add(&pid, sizeof(&pid), 0.0);
328
/* Hash output from child */
331
cmd_eof = error_abort = msec_elapsed = total_bytes_read = 0;
332
while (!error_abort && !cmd_eof) {
337
(void) gettimeofday(&tv_current, 0);
338
msec_elapsed = timeval_diff(&tv_start, &tv_current);
339
if (msec_elapsed >= entropy_timeout_current) {
343
msec_remaining = entropy_timeout_current - msec_elapsed;
346
FD_SET(p[0], &rdset);
347
tv.tv_sec = msec_remaining / 1000;
348
tv.tv_usec = (msec_remaining % 1000) * 1000;
350
ret = select(p[0] + 1, &rdset, NULL, NULL, &tv);
352
RAND_add(&tv, sizeof(tv), 0.0);
363
bytes_read = read(p[0], buf, sizeof(buf));
364
} while (bytes_read == -1 && errno == EINTR);
365
RAND_add(&bytes_read, sizeof(&bytes_read), 0.0);
366
if (bytes_read == -1) {
369
} else if (bytes_read) {
370
SHA1_Update(&sha, buf, bytes_read);
371
total_bytes_read += bytes_read;
379
debug("Command '%s': select() failed: %s",
380
src->cmdstring, strerror(errno));
386
SHA1_Final(hash, &sha);
390
debug3("Time elapsed: %d msec", msec_elapsed);
392
if (waitpid(pid, &status, 0) == -1) {
393
error("Couldn't wait for child '%s' completion: %s",
394
src->cmdstring, strerror(errno));
398
RAND_add(&status, sizeof(&status), 0.0);
402
* Closing p[0] on timeout causes the entropy command to
403
* SIGPIPE. Take whatever output we got, and mark this
406
debug2("Command '%s' timed out", src->cmdstring);
407
src->sticky_badness *= 2;
408
src->badness = src->sticky_badness;
409
return total_bytes_read;
412
if (WIFEXITED(status)) {
413
if (WEXITSTATUS(status) == 0) {
414
return total_bytes_read;
416
debug2("Command '%s' exit status was %d",
417
src->cmdstring, WEXITSTATUS(status));
418
src->badness = src->sticky_badness = 128;
421
} else if (WIFSIGNALED(status)) {
422
debug2("Command '%s' returned on uncaught signal %d !",
423
src->cmdstring, status);
424
src->badness = src->sticky_badness = 128;
431
stir_from_system(void)
433
double total_entropy_estimate;
436
total_entropy_estimate = 0;
439
RAND_add(&i, sizeof(i), 0.5);
440
total_entropy_estimate += 0.1;
443
RAND_add(&i, sizeof(i), 0.5);
444
total_entropy_estimate += 0.1;
447
RAND_add(&i, sizeof(i), 0.0);
449
RAND_add(&i, sizeof(i), 0.0);
451
total_entropy_estimate += stir_gettimeofday(1.0);
452
total_entropy_estimate += stir_clock(0.5);
453
total_entropy_estimate += stir_rusage(RUSAGE_SELF, 2.0);
455
return total_entropy_estimate;
459
stir_from_programs(void)
462
double entropy, total_entropy;
463
unsigned char hash[SHA_DIGEST_LENGTH];
466
for(c = 0; entropy_cmds[c].path != NULL; c++) {
467
if (!entropy_cmds[c].badness) {
468
/* Hash output from command */
469
entropy = hash_command_output(&entropy_cmds[c],
472
/* Scale back estimate by command's rate */
473
entropy *= entropy_cmds[c].rate;
475
/* Upper bound of entropy is SHA_DIGEST_LENGTH */
476
if (entropy > SHA_DIGEST_LENGTH)
477
entropy = SHA_DIGEST_LENGTH;
480
RAND_add(hash, sizeof(hash), entropy);
482
debug3("Got %0.2f bytes of entropy from '%s'",
483
entropy, entropy_cmds[c].cmdstring);
485
total_entropy += entropy;
487
/* Execution time should be a bit unpredictable */
488
total_entropy += stir_gettimeofday(0.05);
489
total_entropy += stir_clock(0.05);
490
total_entropy += stir_rusage(RUSAGE_SELF, 0.1);
491
total_entropy += stir_rusage(RUSAGE_CHILDREN, 0.1);
493
debug2("Command '%s' disabled (badness %d)",
494
entropy_cmds[c].cmdstring,
495
entropy_cmds[c].badness);
497
if (entropy_cmds[c].badness > 0)
498
entropy_cmds[c].badness--;
502
return total_entropy;
506
* prng seedfile functions
509
prng_check_seedfile(char *filename)
514
* XXX raceable: eg replace seed between this stat and subsequent
515
* open. Not such a problem because we don't really trust the
517
* XXX: use secure path checking as elsewhere in OpenSSH
519
if (lstat(filename, &st) == -1) {
520
/* Give up on hard errors */
522
debug("WARNING: Couldn't stat random seed file "
523
"\"%.100s\": %s", filename, strerror(errno));
528
if (!S_ISREG(st.st_mode))
529
fatal("PRNG seedfile %.100s is not a regular file",
532
/* mode 0600, owned by root or the current user? */
533
if (((st.st_mode & 0177) != 0) || !(st.st_uid == getuid())) {
534
debug("WARNING: PRNG seedfile %.100s must be mode 0600, "
535
"owned by uid %li", filename, (long int)getuid());
543
prng_write_seedfile(void)
546
unsigned char seed[SEED_FILE_SIZE];
547
char filename[MAXPATHLEN];
550
pw = getpwuid(getuid());
552
fatal("Couldn't get password entry for current user "
553
"(%li): %s", (long int)getuid(), strerror(errno));
555
/* Try to ensure that the parent directory is there */
556
snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir,
558
mkdir(filename, 0700);
560
snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir,
563
debug("writing PRNG seed to file %.100s", filename);
565
if (RAND_bytes(seed, sizeof(seed)) <= 0)
566
fatal("PRNG seed extraction failed");
568
/* Don't care if the seed doesn't exist */
569
prng_check_seedfile(filename);
571
if ((fd = open(filename, O_WRONLY|O_TRUNC|O_CREAT, 0600)) == -1) {
572
debug("WARNING: couldn't access PRNG seedfile %.100s "
573
"(%.100s)", filename, strerror(errno));
575
if (atomicio(vwrite, fd, &seed, sizeof(seed)) < sizeof(seed))
576
fatal("problem writing PRNG seedfile %.100s "
577
"(%.100s)", filename, strerror(errno));
583
prng_read_seedfile(void)
586
char seed[SEED_FILE_SIZE], filename[MAXPATHLEN];
589
pw = getpwuid(getuid());
591
fatal("Couldn't get password entry for current user "
592
"(%li): %s", (long int)getuid(), strerror(errno));
594
snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir,
597
debug("loading PRNG seed from file %.100s", filename);
599
if (!prng_check_seedfile(filename)) {
600
verbose("Random seed file not found or invalid, ignoring.");
604
/* open the file and read in the seed */
605
fd = open(filename, O_RDONLY);
607
fatal("could not open PRNG seedfile %.100s (%.100s)",
608
filename, strerror(errno));
610
if (atomicio(read, fd, &seed, sizeof(seed)) < sizeof(seed)) {
611
verbose("invalid or short read from PRNG seedfile "
612
"%.100s - ignoring", filename);
613
memset(seed, '\0', sizeof(seed));
617
/* stir in the seed, with estimated entropy zero */
618
RAND_add(&seed, sizeof(seed), 0.0);
623
* entropy command initialisation functions
626
prng_read_commands(char *cmdfilename)
628
char cmd[SEED_FILE_SIZE], *cp, line[1024], path[SEED_FILE_SIZE];
630
entropy_cmd_t *entcmd;
632
int cur_cmd, linenum, num_cmds, arg;
634
if ((f = fopen(cmdfilename, "r")) == NULL) {
635
fatal("couldn't read entropy commands file %.100s: %.100s",
636
cmdfilename, strerror(errno));
640
entcmd = xmalloc(num_cmds * sizeof(entropy_cmd_t));
641
memset(entcmd, '\0', num_cmds * sizeof(entropy_cmd_t));
644
cur_cmd = linenum = 0;
645
while (fgets(line, sizeof(line), f)) {
648
/* Skip leading whitespace, blank lines and comments */
649
cp = line + strspn(line, WHITESPACE);
650
if ((*cp == 0) || (*cp == '#'))
651
continue; /* done with this line */
654
* The first non-whitespace char should be a double quote
655
* delimiting the commandline
658
error("bad entropy command, %.100s line %d",
659
cmdfilename, linenum);
664
* First token, command args (incl. argv[0]) in double
667
cp = strtok(cp, "\"");
669
error("missing or bad command string, %.100s "
670
"line %d -- ignored", cmdfilename, linenum);
673
strlcpy(cmd, cp, sizeof(cmd));
675
/* Second token, full command path */
676
if ((cp = strtok(NULL, WHITESPACE)) == NULL) {
677
error("missing command path, %.100s "
678
"line %d -- ignored", cmdfilename, linenum);
682
/* Did configure mark this as dead? */
683
if (strncmp("undef", cp, 5) == 0)
686
strlcpy(path, cp, sizeof(path));
688
/* Third token, entropy rate estimate for this command */
689
if ((cp = strtok(NULL, WHITESPACE)) == NULL) {
690
error("missing entropy estimate, %.100s "
691
"line %d -- ignored", cmdfilename, linenum);
694
est = strtod(cp, NULL);
697
if ((cp = strtok(NULL, WHITESPACE)) != NULL) {
698
error("garbage at end of line %d in %.100s "
699
"-- ignored", linenum, cmdfilename);
703
/* save the command for debug messages */
704
entcmd[cur_cmd].cmdstring = xstrdup(cmd);
706
/* split the command args */
707
cp = strtok(cmd, WHITESPACE);
710
entcmd[cur_cmd].args[arg] = xstrdup(cp);
712
} while(arg < NUM_ARGS && (cp = strtok(NULL, WHITESPACE)));
714
if (strtok(NULL, WHITESPACE))
715
error("ignored extra commands (max %d), %.100s "
716
"line %d", NUM_ARGS, cmdfilename, linenum);
718
/* Copy the command path and rate estimate */
719
entcmd[cur_cmd].path = xstrdup(path);
720
entcmd[cur_cmd].rate = est;
722
/* Initialise other values */
723
entcmd[cur_cmd].sticky_badness = 1;
728
* If we've filled the array, reallocate it twice the size
729
* Do this now because even if this we're on the last
730
* command we need another slot to mark the last entry
732
if (cur_cmd == num_cmds) {
734
entcmd = xrealloc(entcmd, num_cmds *
735
sizeof(entropy_cmd_t));
739
/* zero the last entry */
740
memset(&entcmd[cur_cmd], '\0', sizeof(entropy_cmd_t));
743
entropy_cmds = xrealloc(entcmd, (cur_cmd + 1) *
744
sizeof(entropy_cmd_t));
746
debug("Loaded %d entropy commands from %.100s", cur_cmd,
749
return cur_cmd < MIN_ENTROPY_SOURCES ? -1 : 0;
755
fprintf(stderr, "Usage: %s [options]\n", __progname);
756
fprintf(stderr, " -v Verbose; display verbose debugging messages.\n");
757
fprintf(stderr, " Multiple -v increases verbosity.\n");
758
fprintf(stderr, " -x Force output in hexidecimal (for debugging)\n");
759
fprintf(stderr, " -X Force output in binary\n");
760
fprintf(stderr, " -b bytes Number of bytes to output (default %d)\n",
765
main(int argc, char **argv)
768
int ret, ch, debug_level, output_hex, bytes;
772
__progname = ssh_get_progname(argv[0]);
773
log_init(argv[0], SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_USER, 1);
775
ll = SYSLOG_LEVEL_INFO;
776
debug_level = output_hex = 0;
777
bytes = OUTPUT_SEED_SIZE;
779
/* Don't write binary data to a tty, unless we are forced to */
780
if (isatty(STDOUT_FILENO))
783
while ((ch = getopt(argc, argv, "vxXhb:")) != -1) {
787
ll = SYSLOG_LEVEL_DEBUG1 + debug_level++;
796
if ((bytes = atoi(optarg)) <= 0)
797
fatal("Invalid number of output bytes");
803
error("Invalid commandline option");
808
log_init(argv[0], ll, SYSLOG_FACILITY_USER, 1);
810
#ifdef USE_SEED_FILES
811
prng_read_seedfile();
814
buf = xmalloc(bytes);
817
* Seed the RNG from wherever we can
820
/* Take whatever is on the stack, but don't credit it */
821
RAND_add(buf, bytes, 0);
823
debug("Seeded RNG with %i bytes from system calls",
824
(int)stir_from_system());
827
if (get_random_bytes_prngd(buf, bytes, PRNGD_PORT, NULL) == -1)
828
fatal("Entropy collection failed");
829
RAND_add(buf, bytes, bytes);
830
#elif defined(PRNGD_SOCKET)
831
if (get_random_bytes_prngd(buf, bytes, 0, PRNGD_SOCKET) == -1)
832
fatal("Entropy collection failed");
833
RAND_add(buf, bytes, bytes);
835
/* Read in collection commands */
836
if (prng_read_commands(SSH_PRNG_COMMAND_FILE) == -1)
837
fatal("PRNG initialisation failed -- exiting.");
838
debug("Seeded RNG with %i bytes from programs",
839
(int)stir_from_programs());
842
#ifdef USE_SEED_FILES
843
prng_write_seedfile();
847
* Write the seed to stdout
851
fatal("Not enough entropy in RNG");
853
if (RAND_bytes(buf, bytes) <= 0)
854
fatal("Couldn't extract entropy from PRNG");
857
for(ret = 0; ret < bytes; ret++)
858
printf("%02x", (unsigned char)(buf[ret]));
861
ret = atomicio(vwrite, STDOUT_FILENO, buf, bytes);
863
memset(buf, '\0', bytes);
866
return ret == bytes ? 0 : 1;
added
removed
ssh-rand-helper.c
