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openssh/entropy.c
Damien Miller 72ef7c148c support --without-openssl at configure time
Disables and removes dependency on OpenSSL. Many features don't
work and the set of crypto options is greatly restricted. This
will only work on system with native arc4random or /dev/urandom.

Considered highly experimental for now.
2015-01-15 02:28:36 +11:00

245 lines
6.1 KiB
C

/*
* 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"
#ifdef WITH_OPENSSL
#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 "openbsd-compat/openssl-compat.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
if (!ssh_compatible_openssl(OPENSSL_VERSION_NUMBER, SSLeay()))
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");
}
#else /* WITH_OPENSSL */
/* Handled in arc4random() */
void
seed_rng(void)
{
}
#endif /* WITH_OPENSSL */