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/*
* Copyright (c) 2001 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 <sys/types.h>
#include <sys/socket.h>
#ifdef HAVE_SYS_UN_H
# include <sys/un.h>
#endif
#include <netinet/in.h>
#include <arpa/inet.h>
#include <errno.h>
#include <signal.h>
#include <string.h>
#include <unistd.h>
#include <stddef.h> /* for offsetof */
#include <openssl/rand.h>
#include <openssl/crypto.h>
#include <openssl/err.h>
#include "ssh.h"
#include "misc.h"
#include "xmalloc.h"
#include "atomicio.h"
#include "pathnames.h"
#include "log.h"
#include "buffer.h"
/*
* Portable OpenSSH PRNG seeding:
* If OpenSSL has not "internally seeded" itself (e.g. pulled data from
* /dev/random), then collect RANDOM_SEED_SIZE bytes of randomness from
* PRNGd.
*/
#ifndef OPENSSL_PRNG_ONLY
#define RANDOM_SEED_SIZE 48
/*
* 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;
u_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 <= 0 || len > 255)
fatal("Too many bytes (%d) to read from PRNGD", len);
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) != (size_t)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;
}
void
rexec_send_rng_seed(Buffer *m)
{
u_char buf[RANDOM_SEED_SIZE];
if (RAND_bytes(buf, sizeof(buf)) <= 0) {
error("Couldn't obtain random bytes (error %ld)",
ERR_get_error());
buffer_put_string(m, "", 0);
} else
buffer_put_string(m, buf, sizeof(buf));
}
void
rexec_recv_rng_seed(Buffer *m)
{
u_char *buf;
u_int len;
buf = buffer_get_string_ret(m, &len);
if (buf != NULL) {
debug3("rexec_recv_rng_seed: seeding rng with %u bytes", len);
RAND_add(buf, len, len);
}
}
#endif /* OPENSSL_PRNG_ONLY */
void
seed_rng(void)
{
#ifndef OPENSSL_PRNG_ONLY
unsigned char buf[RANDOM_SEED_SIZE];
#endif
/*
* OpenSSL version numbers: MNNFFPPS: major minor fix patch status
* We match major, minor, fix and status (not patch) for <1.0.0.
* After that, we acceptable compatible fix versions (so we
* allow 1.0.1 to work with 1.0.0). Going backwards is only allowed
* within a patch series.
*/
u_long version_mask = SSLeay() >= 0x1000000f ? ~0xffff0L : ~0xff0L;
if (((SSLeay() ^ OPENSSL_VERSION_NUMBER) & version_mask) ||
(SSLeay() >> 12) < (OPENSSL_VERSION_NUMBER >> 12))
fatal("OpenSSL version mismatch. Built against %lx, you "
"have %lx", (u_long)OPENSSL_VERSION_NUMBER, SSLeay());
#ifndef OPENSSL_PRNG_ONLY
if (RAND_status() == 1) {
debug3("RNG is ready, skipping seeding");
return;
}
if (seed_from_prngd(buf, sizeof(buf)) == -1)
fatal("Could not obtain seed from PRNGd");
RAND_add(buf, sizeof(buf), sizeof(buf));
memset(buf, '\0', sizeof(buf));
#endif /* OPENSSL_PRNG_ONLY */
if (RAND_status() != 1)
fatal("PRNG is not seeded");
}
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