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sonic-openssh
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sonic-openssh/ssh-rand-helper.c

903 строки
22 KiB
C
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/*
* Copyright (c) 2001-2002 Damien Miller. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "includes.h"
#include <openssl/rand.h>
#include <openssl/sha.h>
#include <openssl/crypto.h>
/* SunOS 4.4.4 needs this */
#ifdef HAVE_FLOATINGPOINT_H
# include <floatingpoint.h>
#endif /* HAVE_FLOATINGPOINT_H */
#include "misc.h"
#include "xmalloc.h"
#include "atomicio.h"
#include "pathnames.h"
#include "log.h"
RCSID("$Id: ssh-rand-helper.c,v 1.23 2005/02/16 02:32:30 dtucker Exp $");
/* Number of bytes we write out */
#define OUTPUT_SEED_SIZE 48
/* Length of on-disk seedfiles */
#define SEED_FILE_SIZE 1024
/* Maximum number of command-line arguments to read from file */
#define NUM_ARGS 10
/* Minimum number of usable commands to be considered sufficient */
#define MIN_ENTROPY_SOURCES 16
/* Path to on-disk seed file (relative to user's home directory */
#ifndef SSH_PRNG_SEED_FILE
# define SSH_PRNG_SEED_FILE _PATH_SSH_USER_DIR"/prng_seed"
#endif
/* Path to PRNG commands list */
#ifndef SSH_PRNG_COMMAND_FILE
# define SSH_PRNG_COMMAND_FILE SSHDIR "/ssh_prng_cmds"
#endif
extern char *__progname;
#define WHITESPACE " \t\n"
#ifndef RUSAGE_SELF
# define RUSAGE_SELF 0
#endif
#ifndef RUSAGE_CHILDREN
# define RUSAGE_CHILDREN 0
#endif
#if !defined(PRNGD_SOCKET) && !defined(PRNGD_PORT)
# define USE_SEED_FILES
#endif
typedef struct {
/* Proportion of data that is entropy */
double rate;
/* Counter goes positive if this command times out */
unsigned int badness;
/* Increases by factor of two each timeout */
unsigned int sticky_badness;
/* Path to executable */
char *path;
/* argv to pass to executable */
char *args[NUM_ARGS]; /* XXX: arbitrary limit */
/* full command string (debug) */
char *cmdstring;
} entropy_cmd_t;
/* slow command timeouts (all in milliseconds) */
/* static int entropy_timeout_default = ENTROPY_TIMEOUT_MSEC; */
static int entropy_timeout_current = ENTROPY_TIMEOUT_MSEC;
/* this is initialised from a file, by prng_read_commands() */
static entropy_cmd_t *entropy_cmds = NULL;
/* Prototypes */
double stir_from_system(void);
double stir_from_programs(void);
double stir_gettimeofday(double entropy_estimate);
double stir_clock(double entropy_estimate);
double stir_rusage(int who, double entropy_estimate);
double hash_command_output(entropy_cmd_t *src, unsigned char *hash);
int get_random_bytes_prngd(unsigned char *buf, int len,
unsigned short tcp_port, char *socket_path);
/*
* Collect 'len' bytes of entropy into 'buf' from PRNGD/EGD daemon
* listening either on 'tcp_port', or via Unix domain socket at *
* 'socket_path'.
* Either a non-zero tcp_port or a non-null socket_path must be
* supplied.
* Returns 0 on success, -1 on error
*/
int
get_random_bytes_prngd(unsigned char *buf, int len,
unsigned short tcp_port, char *socket_path)
{
int fd, addr_len, rval, errors;
char msg[2];
struct sockaddr_storage addr;
struct sockaddr_in *addr_in = (struct sockaddr_in *)&addr;
struct sockaddr_un *addr_un = (struct sockaddr_un *)&addr;
mysig_t old_sigpipe;
/* Sanity checks */
if (socket_path == NULL && tcp_port == 0)
fatal("You must specify a port or a socket");
if (socket_path != NULL &&
strlen(socket_path) >= sizeof(addr_un->sun_path))
fatal("Random pool path is too long");
if (len > 255)
fatal("Too many bytes to read from PRNGD");
memset(&addr, '\0', sizeof(addr));
if (tcp_port != 0) {
addr_in->sin_family = AF_INET;
addr_in->sin_addr.s_addr = htonl(INADDR_LOOPBACK);
addr_in->sin_port = htons(tcp_port);
addr_len = sizeof(*addr_in);
} else {
addr_un->sun_family = AF_UNIX;
strlcpy(addr_un->sun_path, socket_path,
sizeof(addr_un->sun_path));
addr_len = offsetof(struct sockaddr_un, sun_path) +
strlen(socket_path) + 1;
}
old_sigpipe = mysignal(SIGPIPE, SIG_IGN);
errors = 0;
rval = -1;
reopen:
fd = socket(addr.ss_family, SOCK_STREAM, 0);
if (fd == -1) {
error("Couldn't create socket: %s", strerror(errno));
goto done;
}
if (connect(fd, (struct sockaddr*)&addr, addr_len) == -1) {
if (tcp_port != 0) {
error("Couldn't connect to PRNGD port %d: %s",
tcp_port, strerror(errno));
} else {
error("Couldn't connect to PRNGD socket \"%s\": %s",
addr_un->sun_path, strerror(errno));
}
goto done;
}
/* Send blocking read request to PRNGD */
msg[0] = 0x02;
msg[1] = len;
if (atomicio(vwrite, fd, msg, sizeof(msg)) != sizeof(msg)) {
if (errno == EPIPE && errors < 10) {
close(fd);
errors++;
goto reopen;
}
error("Couldn't write to PRNGD socket: %s",
strerror(errno));
goto done;
}
if (atomicio(read, fd, buf, len) != len) {
if (errno == EPIPE && errors < 10) {
close(fd);
errors++;
goto reopen;
}
error("Couldn't read from PRNGD socket: %s",
strerror(errno));
goto done;
}
rval = 0;
done:
mysignal(SIGPIPE, old_sigpipe);
if (fd != -1)
close(fd);
return rval;
}
static int
seed_from_prngd(unsigned char *buf, size_t bytes)
{
#ifdef PRNGD_PORT
debug("trying egd/prngd port %d", PRNGD_PORT);
if (get_random_bytes_prngd(buf, bytes, PRNGD_PORT, NULL) == 0)
return 0;
#endif
#ifdef PRNGD_SOCKET
debug("trying egd/prngd socket %s", PRNGD_SOCKET);
if (get_random_bytes_prngd(buf, bytes, 0, PRNGD_SOCKET) == 0)
return 0;
#endif
return -1;
}
double
stir_gettimeofday(double entropy_estimate)
{
struct timeval tv;
if (gettimeofday(&tv, NULL) == -1)
fatal("Couldn't gettimeofday: %s", strerror(errno));
RAND_add(&tv, sizeof(tv), entropy_estimate);
return entropy_estimate;
}
double
stir_clock(double entropy_estimate)
{
#ifdef HAVE_CLOCK
clock_t c;
c = clock();
RAND_add(&c, sizeof(c), entropy_estimate);
return entropy_estimate;
#else /* _HAVE_CLOCK */
return 0;
#endif /* _HAVE_CLOCK */
}
double
stir_rusage(int who, double entropy_estimate)
{
#ifdef HAVE_GETRUSAGE
struct rusage ru;
if (getrusage(who, &ru) == -1)
return 0;
RAND_add(&ru, sizeof(ru), entropy_estimate);
return entropy_estimate;
#else /* _HAVE_GETRUSAGE */
return 0;
#endif /* _HAVE_GETRUSAGE */
}
static int
timeval_diff(struct timeval *t1, struct timeval *t2)
{
int secdiff, usecdiff;
secdiff = t2->tv_sec - t1->tv_sec;
usecdiff = (secdiff*1000000) + (t2->tv_usec - t1->tv_usec);
return (int)(usecdiff / 1000);
}
double
hash_command_output(entropy_cmd_t *src, unsigned char *hash)
{
char buf[8192];
fd_set rdset;
int bytes_read, cmd_eof, error_abort, msec_elapsed, p[2];
int status, total_bytes_read;
static int devnull = -1;
pid_t pid;
SHA_CTX sha;
struct timeval tv_start, tv_current;
debug3("Reading output from \'%s\'", src->cmdstring);
if (devnull == -1) {
devnull = open("/dev/null", O_RDWR);
if (devnull == -1)
fatal("Couldn't open /dev/null: %s",
strerror(errno));
}
if (pipe(p) == -1)
fatal("Couldn't open pipe: %s", strerror(errno));
(void)gettimeofday(&tv_start, NULL); /* record start time */
switch (pid = fork()) {
case -1: /* Error */
close(p[0]);
close(p[1]);
fatal("Couldn't fork: %s", strerror(errno));
/* NOTREACHED */
case 0: /* Child */
dup2(devnull, STDIN_FILENO);
dup2(p[1], STDOUT_FILENO);
dup2(p[1], STDERR_FILENO);
close(p[0]);
close(p[1]);
close(devnull);
execv(src->path, (char**)(src->args));
debug("(child) Couldn't exec '%s': %s",
src->cmdstring, strerror(errno));
_exit(-1);
default: /* Parent */
break;
}
RAND_add(&pid, sizeof(&pid), 0.0);
close(p[1]);
/* Hash output from child */
SHA1_Init(&sha);
cmd_eof = error_abort = msec_elapsed = total_bytes_read = 0;
while (!error_abort && !cmd_eof) {
int ret;
struct timeval tv;
int msec_remaining;
(void) gettimeofday(&tv_current, 0);
msec_elapsed = timeval_diff(&tv_start, &tv_current);
if (msec_elapsed >= entropy_timeout_current) {
error_abort=1;
continue;
}
msec_remaining = entropy_timeout_current - msec_elapsed;
FD_ZERO(&rdset);
FD_SET(p[0], &rdset);
tv.tv_sec = msec_remaining / 1000;
tv.tv_usec = (msec_remaining % 1000) * 1000;
ret = select(p[0] + 1, &rdset, NULL, NULL, &tv);
RAND_add(&tv, sizeof(tv), 0.0);
switch (ret) {
case 0:
/* timer expired */
error_abort = 1;
kill(pid, SIGINT);
break;
case 1:
/* command input */
do {
bytes_read = read(p[0], buf, sizeof(buf));
} while (bytes_read == -1 && errno == EINTR);
RAND_add(&bytes_read, sizeof(&bytes_read), 0.0);
if (bytes_read == -1) {
error_abort = 1;
break;
} else if (bytes_read) {
SHA1_Update(&sha, buf, bytes_read);
total_bytes_read += bytes_read;
} else {
cmd_eof = 1;
}
break;
case -1:
default:
/* error */
debug("Command '%s': select() failed: %s",
src->cmdstring, strerror(errno));
error_abort = 1;
break;
}
}
SHA1_Final(hash, &sha);
close(p[0]);
debug3("Time elapsed: %d msec", msec_elapsed);
if (waitpid(pid, &status, 0) == -1) {
error("Couldn't wait for child '%s' completion: %s",
src->cmdstring, strerror(errno));
return 0.0;
}
RAND_add(&status, sizeof(&status), 0.0);
if (error_abort) {
/*
* Closing p[0] on timeout causes the entropy command to
* SIGPIPE. Take whatever output we got, and mark this
* command as slow
*/
debug2("Command '%s' timed out", src->cmdstring);
src->sticky_badness *= 2;
src->badness = src->sticky_badness;
return total_bytes_read;
}
if (WIFEXITED(status)) {
if (WEXITSTATUS(status) == 0) {
return total_bytes_read;
} else {
debug2("Command '%s' exit status was %d",
src->cmdstring, WEXITSTATUS(status));
src->badness = src->sticky_badness = 128;
return 0.0;
}
} else if (WIFSIGNALED(status)) {
debug2("Command '%s' returned on uncaught signal %d !",
src->cmdstring, status);
src->badness = src->sticky_badness = 128;
return 0.0;
} else
return 0.0;
}
double
stir_from_system(void)
{
double total_entropy_estimate;
long int i;
total_entropy_estimate = 0;
i = getpid();
RAND_add(&i, sizeof(i), 0.5);
total_entropy_estimate += 0.1;
i = getppid();
RAND_add(&i, sizeof(i), 0.5);
total_entropy_estimate += 0.1;
i = getuid();
RAND_add(&i, sizeof(i), 0.0);
i = getgid();
RAND_add(&i, sizeof(i), 0.0);
total_entropy_estimate += stir_gettimeofday(1.0);
total_entropy_estimate += stir_clock(0.5);
total_entropy_estimate += stir_rusage(RUSAGE_SELF, 2.0);
return total_entropy_estimate;
}
double
stir_from_programs(void)
{
int c;
double entropy, total_entropy;
unsigned char hash[SHA_DIGEST_LENGTH];
total_entropy = 0;
for(c = 0; entropy_cmds[c].path != NULL; c++) {
if (!entropy_cmds[c].badness) {
/* Hash output from command */
entropy = hash_command_output(&entropy_cmds[c],
hash);
/* Scale back estimate by command's rate */
entropy *= entropy_cmds[c].rate;
/* Upper bound of entropy is SHA_DIGEST_LENGTH */
if (entropy > SHA_DIGEST_LENGTH)
entropy = SHA_DIGEST_LENGTH;
/* Stir it in */
RAND_add(hash, sizeof(hash), entropy);
debug3("Got %0.2f bytes of entropy from '%s'",
entropy, entropy_cmds[c].cmdstring);
total_entropy += entropy;
/* Execution time should be a bit unpredictable */
total_entropy += stir_gettimeofday(0.05);
total_entropy += stir_clock(0.05);
total_entropy += stir_rusage(RUSAGE_SELF, 0.1);
total_entropy += stir_rusage(RUSAGE_CHILDREN, 0.1);
} else {
debug2("Command '%s' disabled (badness %d)",
entropy_cmds[c].cmdstring,
entropy_cmds[c].badness);
if (entropy_cmds[c].badness > 0)
entropy_cmds[c].badness--;
}
}
return total_entropy;
}
/*
* prng seedfile functions
*/
int
prng_check_seedfile(char *filename)
{
struct stat st;
/*
* XXX raceable: eg replace seed between this stat and subsequent
* open. Not such a problem because we don't really trust the
* seed file anyway.
* XXX: use secure path checking as elsewhere in OpenSSH
*/
if (lstat(filename, &st) == -1) {
/* Give up on hard errors */
if (errno != ENOENT)
debug("WARNING: Couldn't stat random seed file "
"\"%.100s\": %s", filename, strerror(errno));
return 0;
}
/* regular file? */
if (!S_ISREG(st.st_mode))
fatal("PRNG seedfile %.100s is not a regular file",
filename);
/* mode 0600, owned by root or the current user? */
if (((st.st_mode & 0177) != 0) || !(st.st_uid == getuid())) {
debug("WARNING: PRNG seedfile %.100s must be mode 0600, "
"owned by uid %li", filename, (long int)getuid());
return 0;
}
return 1;
}
void
prng_write_seedfile(void)
{
int fd, save_errno;
unsigned char seed[SEED_FILE_SIZE];
char filename[MAXPATHLEN], tmpseed[MAXPATHLEN];
struct passwd *pw;
mode_t old_umask;
pw = getpwuid(getuid());
if (pw == NULL)
fatal("Couldn't get password entry for current user "
"(%li): %s", (long int)getuid(), strerror(errno));
/* Try to ensure that the parent directory is there */
snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir,
_PATH_SSH_USER_DIR);
mkdir(filename, 0700);
snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir,
SSH_PRNG_SEED_FILE);
strlcpy(tmpseed, filename, sizeof(tmpseed));
if (strlcat(tmpseed, ".XXXXXXXXXX", sizeof(tmpseed)) >=
sizeof(tmpseed))
fatal("PRNG seed filename too long");
if (RAND_bytes(seed, sizeof(seed)) <= 0)
fatal("PRNG seed extraction failed");
/* Don't care if the seed doesn't exist */
prng_check_seedfile(filename);
old_umask = umask(0177);
if ((fd = mkstemp(tmpseed)) == -1) {
debug("WARNING: couldn't make temporary PRNG seedfile %.100s "
"(%.100s)", tmpseed, strerror(errno));
} else {
debug("writing PRNG seed to file %.100s", tmpseed);
if (atomicio(vwrite, fd, &seed, sizeof(seed)) < sizeof(seed)) {
save_errno = errno;
close(fd);
unlink(tmpseed);
fatal("problem writing PRNG seedfile %.100s "
"(%.100s)", filename, strerror(save_errno));
}
close(fd);
debug("moving temporary PRNG seed to file %.100s", filename);
if (rename(tmpseed, filename) == -1) {
save_errno = errno;
unlink(tmpseed);
fatal("problem renaming PRNG seedfile from %.100s "
"to %.100s (%.100s)", tmpseed, filename,
strerror(save_errno));
}
}
umask(old_umask);
}
void
prng_read_seedfile(void)
{
int fd;
char seed[SEED_FILE_SIZE], filename[MAXPATHLEN];
struct passwd *pw;
pw = getpwuid(getuid());
if (pw == NULL)
fatal("Couldn't get password entry for current user "
"(%li): %s", (long int)getuid(), strerror(errno));
snprintf(filename, sizeof(filename), "%.512s/%s", pw->pw_dir,
SSH_PRNG_SEED_FILE);
debug("loading PRNG seed from file %.100s", filename);
if (!prng_check_seedfile(filename)) {
verbose("Random seed file not found or invalid, ignoring.");
return;
}
/* open the file and read in the seed */
fd = open(filename, O_RDONLY);
if (fd == -1)
fatal("could not open PRNG seedfile %.100s (%.100s)",
filename, strerror(errno));
if (atomicio(read, fd, &seed, sizeof(seed)) < sizeof(seed)) {
verbose("invalid or short read from PRNG seedfile "
"%.100s - ignoring", filename);
memset(seed, '\0', sizeof(seed));
}
close(fd);
/* stir in the seed, with estimated entropy zero */
RAND_add(&seed, sizeof(seed), 0.0);
}
/*
* entropy command initialisation functions
*/
int
prng_read_commands(char *cmdfilename)
{
char cmd[SEED_FILE_SIZE], *cp, line[1024], path[SEED_FILE_SIZE];
double est;
entropy_cmd_t *entcmd;
FILE *f;
int cur_cmd, linenum, num_cmds, arg;
if ((f = fopen(cmdfilename, "r")) == NULL) {
fatal("couldn't read entropy commands file %.100s: %.100s",
cmdfilename, strerror(errno));
}
num_cmds = 64;
entcmd = xmalloc(num_cmds * sizeof(entropy_cmd_t));
memset(entcmd, '\0', num_cmds * sizeof(entropy_cmd_t));
/* Read in file */
cur_cmd = linenum = 0;
while (fgets(line, sizeof(line), f)) {
linenum++;
/* Skip leading whitespace, blank lines and comments */
cp = line + strspn(line, WHITESPACE);
if ((*cp == 0) || (*cp == '#'))
continue; /* done with this line */
/*
* The first non-whitespace char should be a double quote
* delimiting the commandline
*/
if (*cp != '"') {
error("bad entropy command, %.100s line %d",
cmdfilename, linenum);
continue;
}
/*
* First token, command args (incl. argv[0]) in double
* quotes
*/
cp = strtok(cp, "\"");
if (cp == NULL) {
error("missing or bad command string, %.100s "
"line %d -- ignored", cmdfilename, linenum);
continue;
}
strlcpy(cmd, cp, sizeof(cmd));
/* Second token, full command path */
if ((cp = strtok(NULL, WHITESPACE)) == NULL) {
error("missing command path, %.100s "
"line %d -- ignored", cmdfilename, linenum);
continue;
}
/* Did configure mark this as dead? */
if (strncmp("undef", cp, 5) == 0)
continue;
strlcpy(path, cp, sizeof(path));
/* Third token, entropy rate estimate for this command */
if ((cp = strtok(NULL, WHITESPACE)) == NULL) {
error("missing entropy estimate, %.100s "
"line %d -- ignored", cmdfilename, linenum);
continue;
}
est = strtod(cp, NULL);
/* end of line */
if ((cp = strtok(NULL, WHITESPACE)) != NULL) {
error("garbage at end of line %d in %.100s "
"-- ignored", linenum, cmdfilename);
continue;
}
/* save the command for debug messages */
entcmd[cur_cmd].cmdstring = xstrdup(cmd);
/* split the command args */
cp = strtok(cmd, WHITESPACE);
arg = 0;
do {
entcmd[cur_cmd].args[arg] = xstrdup(cp);
arg++;
} while(arg < NUM_ARGS && (cp = strtok(NULL, WHITESPACE)));
if (strtok(NULL, WHITESPACE))
error("ignored extra commands (max %d), %.100s "
"line %d", NUM_ARGS, cmdfilename, linenum);
/* Copy the command path and rate estimate */
entcmd[cur_cmd].path = xstrdup(path);
entcmd[cur_cmd].rate = est;
/* Initialise other values */
entcmd[cur_cmd].sticky_badness = 1;
cur_cmd++;
/*
* If we've filled the array, reallocate it twice the size
* Do this now because even if this we're on the last
* command we need another slot to mark the last entry
*/
if (cur_cmd == num_cmds) {
num_cmds *= 2;
entcmd = xrealloc(entcmd, num_cmds *
sizeof(entropy_cmd_t));
}
}
/* zero the last entry */
memset(&entcmd[cur_cmd], '\0', sizeof(entropy_cmd_t));
/* trim to size */
entropy_cmds = xrealloc(entcmd, (cur_cmd + 1) *
sizeof(entropy_cmd_t));
debug("Loaded %d entropy commands from %.100s", cur_cmd,
cmdfilename);
return cur_cmd < MIN_ENTROPY_SOURCES ? -1 : 0;
}
void
usage(void)
{
fprintf(stderr, "Usage: %s [options]\n", __progname);
fprintf(stderr, " -v Verbose; display verbose debugging messages.\n");
fprintf(stderr, " Multiple -v increases verbosity.\n");
fprintf(stderr, " -x Force output in hexadecimal (for debugging)\n");
fprintf(stderr, " -X Force output in binary\n");
fprintf(stderr, " -b bytes Number of bytes to output (default %d)\n",
OUTPUT_SEED_SIZE);
}
int
main(int argc, char **argv)
{
unsigned char *buf;
int ret, ch, debug_level, output_hex, bytes;
extern char *optarg;
LogLevel ll;
__progname = ssh_get_progname(argv[0]);
log_init(argv[0], SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_USER, 1);
ll = SYSLOG_LEVEL_INFO;
debug_level = output_hex = 0;
bytes = OUTPUT_SEED_SIZE;
/* Don't write binary data to a tty, unless we are forced to */
if (isatty(STDOUT_FILENO))
output_hex = 1;
while ((ch = getopt(argc, argv, "vxXhb:")) != -1) {
switch (ch) {
case 'v':
if (debug_level < 3)
ll = SYSLOG_LEVEL_DEBUG1 + debug_level++;
break;
case 'x':
output_hex = 1;
break;
case 'X':
output_hex = 0;
break;
case 'b':
if ((bytes = atoi(optarg)) <= 0)
fatal("Invalid number of output bytes");
break;
case 'h':
usage();
exit(0);
default:
error("Invalid commandline option");
usage();
}
}
log_init(argv[0], ll, SYSLOG_FACILITY_USER, 1);
#ifdef USE_SEED_FILES
prng_read_seedfile();
#endif
buf = xmalloc(bytes);
/*
* Seed the RNG from wherever we can
*/
/* Take whatever is on the stack, but don't credit it */
RAND_add(buf, bytes, 0);
debug("Seeded RNG with %i bytes from system calls",
(int)stir_from_system());
/* try prngd, fall back to commands if prngd fails or not configured */
if (seed_from_prngd(buf, bytes) == 0) {
RAND_add(buf, bytes, bytes);
} else {
/* Read in collection commands */
if (prng_read_commands(SSH_PRNG_COMMAND_FILE) == -1)
fatal("PRNG initialisation failed -- exiting.");
debug("Seeded RNG with %i bytes from programs",
(int)stir_from_programs());
}
#ifdef USE_SEED_FILES
prng_write_seedfile();
#endif
/*
* Write the seed to stdout
*/
if (!RAND_status())
fatal("Not enough entropy in RNG");
if (RAND_bytes(buf, bytes) <= 0)
fatal("Couldn't extract entropy from PRNG");
if (output_hex) {
for(ret = 0; ret < bytes; ret++)
printf("%02x", (unsigned char)(buf[ret]));
printf("\n");
} else
ret = atomicio(vwrite, STDOUT_FILENO, buf, bytes);
memset(buf, '\0', bytes);
xfree(buf);
return ret == bytes ? 0 : 1;
}
/*
* We may attempt to re-seed during mkstemp if we are using the one in the
* compat library (via mkstemp -> _gettemp -> arc4random -> seed_rng) so we
* need our own seed_rng(). We must also check that we have enough entropy.
*/
void
seed_rng(void)
{
if (!RAND_status())
fatal("Not enough entropy in RNG");
}
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