File: [local] / src / usr.bin / ssh / packet.c (download)
Revision 1.313, Mon Dec 18 14:45:17 2023 UTC (4 months, 4 weeks ago) by djm
Branch: MAIN
CVS Tags: OPENBSD_7_5_BASE, OPENBSD_7_5
Changes since 1.312: +59 -44 lines
implement "strict key exchange" in ssh and sshd
This adds a protocol extension to improve the integrity of the SSH
transport protocol, particular in and around the initial key exchange
(KEX) phase.
Full details of the extension are in the PROTOCOL file.
with markus@
|
/* $OpenBSD: packet.c,v 1.313 2023/12/18 14:45:17 djm Exp $ */
/*
* Author: Tatu Ylonen <ylo@cs.hut.fi>
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
* All rights reserved
* This file contains code implementing the packet protocol and communication
* with the other side. This same code is used both on client and server side.
*
* As far as I am concerned, the code I have written for this software
* can be used freely for any purpose. Any derived versions of this
* software must be clearly marked as such, and if the derived work is
* incompatible with the protocol description in the RFC file, it must be
* called by a name other than "ssh" or "Secure Shell".
*
*
* SSH2 packet format added by Markus Friedl.
* Copyright (c) 2000, 2001 Markus Friedl. 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 <sys/types.h>
#include <sys/queue.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <errno.h>
#include <netdb.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <limits.h>
#include <poll.h>
#include <signal.h>
#include <time.h>
#ifdef WITH_ZLIB
#include <zlib.h>
#endif
#include "xmalloc.h"
#include "compat.h"
#include "ssh2.h"
#include "cipher.h"
#include "sshkey.h"
#include "kex.h"
#include "digest.h"
#include "mac.h"
#include "log.h"
#include "canohost.h"
#include "misc.h"
#include "channels.h"
#include "ssh.h"
#include "packet.h"
#include "ssherr.h"
#include "sshbuf.h"
#ifdef PACKET_DEBUG
#define DBG(x) x
#else
#define DBG(x)
#endif
#define PACKET_MAX_SIZE (256 * 1024)
struct packet_state {
u_int32_t seqnr;
u_int32_t packets;
u_int64_t blocks;
u_int64_t bytes;
};
struct packet {
TAILQ_ENTRY(packet) next;
u_char type;
struct sshbuf *payload;
};
struct session_state {
/*
* This variable contains the file descriptors used for
* communicating with the other side. connection_in is used for
* reading; connection_out for writing. These can be the same
* descriptor, in which case it is assumed to be a socket.
*/
int connection_in;
int connection_out;
/* Protocol flags for the remote side. */
u_int remote_protocol_flags;
/* Encryption context for receiving data. Only used for decryption. */
struct sshcipher_ctx *receive_context;
/* Encryption context for sending data. Only used for encryption. */
struct sshcipher_ctx *send_context;
/* Buffer for raw input data from the socket. */
struct sshbuf *input;
/* Buffer for raw output data going to the socket. */
struct sshbuf *output;
/* Buffer for the partial outgoing packet being constructed. */
struct sshbuf *outgoing_packet;
/* Buffer for the incoming packet currently being processed. */
struct sshbuf *incoming_packet;
/* Scratch buffer for packet compression/decompression. */
struct sshbuf *compression_buffer;
#ifdef WITH_ZLIB
/* Incoming/outgoing compression dictionaries */
z_stream compression_in_stream;
z_stream compression_out_stream;
#endif
int compression_in_started;
int compression_out_started;
int compression_in_failures;
int compression_out_failures;
/* default maximum packet size */
u_int max_packet_size;
/* Flag indicating whether this module has been initialized. */
int initialized;
/* Set to true if the connection is interactive. */
int interactive_mode;
/* Set to true if we are the server side. */
int server_side;
/* Set to true if we are authenticated. */
int after_authentication;
int keep_alive_timeouts;
/* The maximum time that we will wait to send or receive a packet */
int packet_timeout_ms;
/* Session key information for Encryption and MAC */
struct newkeys *newkeys[MODE_MAX];
struct packet_state p_read, p_send;
/* Volume-based rekeying */
u_int64_t max_blocks_in, max_blocks_out, rekey_limit;
/* Time-based rekeying */
u_int32_t rekey_interval; /* how often in seconds */
time_t rekey_time; /* time of last rekeying */
/* roundup current message to extra_pad bytes */
u_char extra_pad;
/* XXX discard incoming data after MAC error */
u_int packet_discard;
size_t packet_discard_mac_already;
struct sshmac *packet_discard_mac;
/* Used in packet_read_poll2() */
u_int packlen;
/* Used in packet_send2 */
int rekeying;
/* Used in ssh_packet_send_mux() */
int mux;
/* Used in packet_set_interactive */
int set_interactive_called;
/* Used in packet_set_maxsize */
int set_maxsize_called;
/* One-off warning about weak ciphers */
int cipher_warning_done;
/* Hook for fuzzing inbound packets */
ssh_packet_hook_fn *hook_in;
void *hook_in_ctx;
TAILQ_HEAD(, packet) outgoing;
};
struct ssh *
ssh_alloc_session_state(void)
{
struct ssh *ssh = NULL;
struct session_state *state = NULL;
if ((ssh = calloc(1, sizeof(*ssh))) == NULL ||
(state = calloc(1, sizeof(*state))) == NULL ||
(ssh->kex = kex_new()) == NULL ||
(state->input = sshbuf_new()) == NULL ||
(state->output = sshbuf_new()) == NULL ||
(state->outgoing_packet = sshbuf_new()) == NULL ||
(state->incoming_packet = sshbuf_new()) == NULL)
goto fail;
TAILQ_INIT(&state->outgoing);
TAILQ_INIT(&ssh->private_keys);
TAILQ_INIT(&ssh->public_keys);
state->connection_in = -1;
state->connection_out = -1;
state->max_packet_size = 32768;
state->packet_timeout_ms = -1;
state->p_send.packets = state->p_read.packets = 0;
state->initialized = 1;
/*
* ssh_packet_send2() needs to queue packets until
* we've done the initial key exchange.
*/
state->rekeying = 1;
ssh->state = state;
return ssh;
fail:
if (ssh) {
kex_free(ssh->kex);
free(ssh);
}
if (state) {
sshbuf_free(state->input);
sshbuf_free(state->output);
sshbuf_free(state->incoming_packet);
sshbuf_free(state->outgoing_packet);
free(state);
}
return NULL;
}
void
ssh_packet_set_input_hook(struct ssh *ssh, ssh_packet_hook_fn *hook, void *ctx)
{
ssh->state->hook_in = hook;
ssh->state->hook_in_ctx = ctx;
}
/* Returns nonzero if rekeying is in progress */
int
ssh_packet_is_rekeying(struct ssh *ssh)
{
return ssh->state->rekeying ||
(ssh->kex != NULL && ssh->kex->done == 0);
}
/*
* Sets the descriptors used for communication.
*/
struct ssh *
ssh_packet_set_connection(struct ssh *ssh, int fd_in, int fd_out)
{
struct session_state *state;
const struct sshcipher *none = cipher_by_name("none");
int r;
if (none == NULL) {
error_f("cannot load cipher 'none'");
return NULL;
}
if (ssh == NULL)
ssh = ssh_alloc_session_state();
if (ssh == NULL) {
error_f("could not allocate state");
return NULL;
}
state = ssh->state;
state->connection_in = fd_in;
state->connection_out = fd_out;
if ((r = cipher_init(&state->send_context, none,
(const u_char *)"", 0, NULL, 0, CIPHER_ENCRYPT)) != 0 ||
(r = cipher_init(&state->receive_context, none,
(const u_char *)"", 0, NULL, 0, CIPHER_DECRYPT)) != 0) {
error_fr(r, "cipher_init failed");
free(ssh); /* XXX need ssh_free_session_state? */
return NULL;
}
state->newkeys[MODE_IN] = state->newkeys[MODE_OUT] = NULL;
/*
* Cache the IP address of the remote connection for use in error
* messages that might be generated after the connection has closed.
*/
(void)ssh_remote_ipaddr(ssh);
return ssh;
}
void
ssh_packet_set_timeout(struct ssh *ssh, int timeout, int count)
{
struct session_state *state = ssh->state;
if (timeout <= 0 || count <= 0) {
state->packet_timeout_ms = -1;
return;
}
if ((INT_MAX / 1000) / count < timeout)
state->packet_timeout_ms = INT_MAX;
else
state->packet_timeout_ms = timeout * count * 1000;
}
void
ssh_packet_set_mux(struct ssh *ssh)
{
ssh->state->mux = 1;
ssh->state->rekeying = 0;
kex_free(ssh->kex);
ssh->kex = NULL;
}
int
ssh_packet_get_mux(struct ssh *ssh)
{
return ssh->state->mux;
}
int
ssh_packet_set_log_preamble(struct ssh *ssh, const char *fmt, ...)
{
va_list args;
int r;
free(ssh->log_preamble);
if (fmt == NULL)
ssh->log_preamble = NULL;
else {
va_start(args, fmt);
r = vasprintf(&ssh->log_preamble, fmt, args);
va_end(args);
if (r < 0 || ssh->log_preamble == NULL)
return SSH_ERR_ALLOC_FAIL;
}
return 0;
}
int
ssh_packet_stop_discard(struct ssh *ssh)
{
struct session_state *state = ssh->state;
int r;
if (state->packet_discard_mac) {
char buf[1024];
size_t dlen = PACKET_MAX_SIZE;
if (dlen > state->packet_discard_mac_already)
dlen -= state->packet_discard_mac_already;
memset(buf, 'a', sizeof(buf));
while (sshbuf_len(state->incoming_packet) < dlen)
if ((r = sshbuf_put(state->incoming_packet, buf,
sizeof(buf))) != 0)
return r;
(void) mac_compute(state->packet_discard_mac,
state->p_read.seqnr,
sshbuf_ptr(state->incoming_packet), dlen,
NULL, 0);
}
logit("Finished discarding for %.200s port %d",
ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
return SSH_ERR_MAC_INVALID;
}
static int
ssh_packet_start_discard(struct ssh *ssh, struct sshenc *enc,
struct sshmac *mac, size_t mac_already, u_int discard)
{
struct session_state *state = ssh->state;
int r;
if (enc == NULL || !cipher_is_cbc(enc->cipher) || (mac && mac->etm)) {
if ((r = sshpkt_disconnect(ssh, "Packet corrupt")) != 0)
return r;
return SSH_ERR_MAC_INVALID;
}
/*
* Record number of bytes over which the mac has already
* been computed in order to minimize timing attacks.
*/
if (mac && mac->enabled) {
state->packet_discard_mac = mac;
state->packet_discard_mac_already = mac_already;
}
if (sshbuf_len(state->input) >= discard)
return ssh_packet_stop_discard(ssh);
state->packet_discard = discard - sshbuf_len(state->input);
return 0;
}
/* Returns 1 if remote host is connected via socket, 0 if not. */
int
ssh_packet_connection_is_on_socket(struct ssh *ssh)
{
struct session_state *state;
struct sockaddr_storage from, to;
socklen_t fromlen, tolen;
if (ssh == NULL || ssh->state == NULL)
return 0;
state = ssh->state;
if (state->connection_in == -1 || state->connection_out == -1)
return 0;
/* filedescriptors in and out are the same, so it's a socket */
if (state->connection_in == state->connection_out)
return 1;
fromlen = sizeof(from);
memset(&from, 0, sizeof(from));
if (getpeername(state->connection_in, (struct sockaddr *)&from,
&fromlen) == -1)
return 0;
tolen = sizeof(to);
memset(&to, 0, sizeof(to));
if (getpeername(state->connection_out, (struct sockaddr *)&to,
&tolen) == -1)
return 0;
if (fromlen != tolen || memcmp(&from, &to, fromlen) != 0)
return 0;
if (from.ss_family != AF_INET && from.ss_family != AF_INET6)
return 0;
return 1;
}
void
ssh_packet_get_bytes(struct ssh *ssh, u_int64_t *ibytes, u_int64_t *obytes)
{
if (ibytes)
*ibytes = ssh->state->p_read.bytes;
if (obytes)
*obytes = ssh->state->p_send.bytes;
}
int
ssh_packet_connection_af(struct ssh *ssh)
{
return get_sock_af(ssh->state->connection_out);
}
/* Sets the connection into non-blocking mode. */
void
ssh_packet_set_nonblocking(struct ssh *ssh)
{
/* Set the socket into non-blocking mode. */
set_nonblock(ssh->state->connection_in);
if (ssh->state->connection_out != ssh->state->connection_in)
set_nonblock(ssh->state->connection_out);
}
/* Returns the socket used for reading. */
int
ssh_packet_get_connection_in(struct ssh *ssh)
{
return ssh->state->connection_in;
}
/* Returns the descriptor used for writing. */
int
ssh_packet_get_connection_out(struct ssh *ssh)
{
return ssh->state->connection_out;
}
/*
* Returns the IP-address of the remote host as a string. The returned
* string must not be freed.
*/
const char *
ssh_remote_ipaddr(struct ssh *ssh)
{
int sock;
/* Check whether we have cached the ipaddr. */
if (ssh->remote_ipaddr == NULL) {
if (ssh_packet_connection_is_on_socket(ssh)) {
sock = ssh->state->connection_in;
ssh->remote_ipaddr = get_peer_ipaddr(sock);
ssh->remote_port = get_peer_port(sock);
ssh->local_ipaddr = get_local_ipaddr(sock);
ssh->local_port = get_local_port(sock);
} else {
ssh->remote_ipaddr = xstrdup("UNKNOWN");
ssh->remote_port = 65535;
ssh->local_ipaddr = xstrdup("UNKNOWN");
ssh->local_port = 65535;
}
}
return ssh->remote_ipaddr;
}
/* Returns the port number of the remote host. */
int
ssh_remote_port(struct ssh *ssh)
{
(void)ssh_remote_ipaddr(ssh); /* Will lookup and cache. */
return ssh->remote_port;
}
/*
* Returns the IP-address of the local host as a string. The returned
* string must not be freed.
*/
const char *
ssh_local_ipaddr(struct ssh *ssh)
{
(void)ssh_remote_ipaddr(ssh); /* Will lookup and cache. */
return ssh->local_ipaddr;
}
/* Returns the port number of the local host. */
int
ssh_local_port(struct ssh *ssh)
{
(void)ssh_remote_ipaddr(ssh); /* Will lookup and cache. */
return ssh->local_port;
}
/* Returns the routing domain of the input socket, or NULL if unavailable */
const char *
ssh_packet_rdomain_in(struct ssh *ssh)
{
if (ssh->rdomain_in != NULL)
return ssh->rdomain_in;
if (!ssh_packet_connection_is_on_socket(ssh))
return NULL;
ssh->rdomain_in = get_rdomain(ssh->state->connection_in);
return ssh->rdomain_in;
}
/* Closes the connection and clears and frees internal data structures. */
static void
ssh_packet_close_internal(struct ssh *ssh, int do_close)
{
struct session_state *state = ssh->state;
u_int mode;
if (!state->initialized)
return;
state->initialized = 0;
if (do_close) {
if (state->connection_in == state->connection_out) {
close(state->connection_out);
} else {
close(state->connection_in);
close(state->connection_out);
}
}
sshbuf_free(state->input);
sshbuf_free(state->output);
sshbuf_free(state->outgoing_packet);
sshbuf_free(state->incoming_packet);
for (mode = 0; mode < MODE_MAX; mode++) {
kex_free_newkeys(state->newkeys[mode]); /* current keys */
state->newkeys[mode] = NULL;
ssh_clear_newkeys(ssh, mode); /* next keys */
}
#ifdef WITH_ZLIB
/* compression state is in shared mem, so we can only release it once */
if (do_close && state->compression_buffer) {
sshbuf_free(state->compression_buffer);
if (state->compression_out_started) {
z_streamp stream = &state->compression_out_stream;
debug("compress outgoing: "
"raw data %llu, compressed %llu, factor %.2f",
(unsigned long long)stream->total_in,
(unsigned long long)stream->total_out,
stream->total_in == 0 ? 0.0 :
(double) stream->total_out / stream->total_in);
if (state->compression_out_failures == 0)
deflateEnd(stream);
}
if (state->compression_in_started) {
z_streamp stream = &state->compression_in_stream;
debug("compress incoming: "
"raw data %llu, compressed %llu, factor %.2f",
(unsigned long long)stream->total_out,
(unsigned long long)stream->total_in,
stream->total_out == 0 ? 0.0 :
(double) stream->total_in / stream->total_out);
if (state->compression_in_failures == 0)
inflateEnd(stream);
}
}
#endif /* WITH_ZLIB */
cipher_free(state->send_context);
cipher_free(state->receive_context);
state->send_context = state->receive_context = NULL;
if (do_close) {
free(ssh->local_ipaddr);
ssh->local_ipaddr = NULL;
free(ssh->remote_ipaddr);
ssh->remote_ipaddr = NULL;
free(ssh->state);
ssh->state = NULL;
kex_free(ssh->kex);
ssh->kex = NULL;
}
}
void
ssh_packet_close(struct ssh *ssh)
{
ssh_packet_close_internal(ssh, 1);
}
void
ssh_packet_clear_keys(struct ssh *ssh)
{
ssh_packet_close_internal(ssh, 0);
}
/* Sets remote side protocol flags. */
void
ssh_packet_set_protocol_flags(struct ssh *ssh, u_int protocol_flags)
{
ssh->state->remote_protocol_flags = protocol_flags;
}
/* Returns the remote protocol flags set earlier by the above function. */
u_int
ssh_packet_get_protocol_flags(struct ssh *ssh)
{
return ssh->state->remote_protocol_flags;
}
/*
* Starts packet compression from the next packet on in both directions.
* Level is compression level 1 (fastest) - 9 (slow, best) as in gzip.
*/
static int
ssh_packet_init_compression(struct ssh *ssh)
{
if (!ssh->state->compression_buffer &&
((ssh->state->compression_buffer = sshbuf_new()) == NULL))
return SSH_ERR_ALLOC_FAIL;
return 0;
}
#ifdef WITH_ZLIB
static int
start_compression_out(struct ssh *ssh, int level)
{
if (level < 1 || level > 9)
return SSH_ERR_INVALID_ARGUMENT;
debug("Enabling compression at level %d.", level);
if (ssh->state->compression_out_started == 1)
deflateEnd(&ssh->state->compression_out_stream);
switch (deflateInit(&ssh->state->compression_out_stream, level)) {
case Z_OK:
ssh->state->compression_out_started = 1;
break;
case Z_MEM_ERROR:
return SSH_ERR_ALLOC_FAIL;
default:
return SSH_ERR_INTERNAL_ERROR;
}
return 0;
}
static int
start_compression_in(struct ssh *ssh)
{
if (ssh->state->compression_in_started == 1)
inflateEnd(&ssh->state->compression_in_stream);
switch (inflateInit(&ssh->state->compression_in_stream)) {
case Z_OK:
ssh->state->compression_in_started = 1;
break;
case Z_MEM_ERROR:
return SSH_ERR_ALLOC_FAIL;
default:
return SSH_ERR_INTERNAL_ERROR;
}
return 0;
}
/* XXX remove need for separate compression buffer */
static int
compress_buffer(struct ssh *ssh, struct sshbuf *in, struct sshbuf *out)
{
u_char buf[4096];
int r, status;
if (ssh->state->compression_out_started != 1)
return SSH_ERR_INTERNAL_ERROR;
/* This case is not handled below. */
if (sshbuf_len(in) == 0)
return 0;
/* Input is the contents of the input buffer. */
if ((ssh->state->compression_out_stream.next_in =
sshbuf_mutable_ptr(in)) == NULL)
return SSH_ERR_INTERNAL_ERROR;
ssh->state->compression_out_stream.avail_in = sshbuf_len(in);
/* Loop compressing until deflate() returns with avail_out != 0. */
do {
/* Set up fixed-size output buffer. */
ssh->state->compression_out_stream.next_out = buf;
ssh->state->compression_out_stream.avail_out = sizeof(buf);
/* Compress as much data into the buffer as possible. */
status = deflate(&ssh->state->compression_out_stream,
Z_PARTIAL_FLUSH);
switch (status) {
case Z_MEM_ERROR:
return SSH_ERR_ALLOC_FAIL;
case Z_OK:
/* Append compressed data to output_buffer. */
if ((r = sshbuf_put(out, buf, sizeof(buf) -
ssh->state->compression_out_stream.avail_out)) != 0)
return r;
break;
case Z_STREAM_ERROR:
default:
ssh->state->compression_out_failures++;
return SSH_ERR_INVALID_FORMAT;
}
} while (ssh->state->compression_out_stream.avail_out == 0);
return 0;
}
static int
uncompress_buffer(struct ssh *ssh, struct sshbuf *in, struct sshbuf *out)
{
u_char buf[4096];
int r, status;
if (ssh->state->compression_in_started != 1)
return SSH_ERR_INTERNAL_ERROR;
if ((ssh->state->compression_in_stream.next_in =
sshbuf_mutable_ptr(in)) == NULL)
return SSH_ERR_INTERNAL_ERROR;
ssh->state->compression_in_stream.avail_in = sshbuf_len(in);
for (;;) {
/* Set up fixed-size output buffer. */
ssh->state->compression_in_stream.next_out = buf;
ssh->state->compression_in_stream.avail_out = sizeof(buf);
status = inflate(&ssh->state->compression_in_stream,
Z_SYNC_FLUSH);
switch (status) {
case Z_OK:
if ((r = sshbuf_put(out, buf, sizeof(buf) -
ssh->state->compression_in_stream.avail_out)) != 0)
return r;
break;
case Z_BUF_ERROR:
/*
* Comments in zlib.h say that we should keep calling
* inflate() until we get an error. This appears to
* be the error that we get.
*/
return 0;
case Z_DATA_ERROR:
return SSH_ERR_INVALID_FORMAT;
case Z_MEM_ERROR:
return SSH_ERR_ALLOC_FAIL;
case Z_STREAM_ERROR:
default:
ssh->state->compression_in_failures++;
return SSH_ERR_INTERNAL_ERROR;
}
}
/* NOTREACHED */
}
#else /* WITH_ZLIB */
static int
start_compression_out(struct ssh *ssh, int level)
{
return SSH_ERR_INTERNAL_ERROR;
}
static int
start_compression_in(struct ssh *ssh)
{
return SSH_ERR_INTERNAL_ERROR;
}
static int
compress_buffer(struct ssh *ssh, struct sshbuf *in, struct sshbuf *out)
{
return SSH_ERR_INTERNAL_ERROR;
}
static int
uncompress_buffer(struct ssh *ssh, struct sshbuf *in, struct sshbuf *out)
{
return SSH_ERR_INTERNAL_ERROR;
}
#endif /* WITH_ZLIB */
void
ssh_clear_newkeys(struct ssh *ssh, int mode)
{
if (ssh->kex && ssh->kex->newkeys[mode]) {
kex_free_newkeys(ssh->kex->newkeys[mode]);
ssh->kex->newkeys[mode] = NULL;
}
}
int
ssh_set_newkeys(struct ssh *ssh, int mode)
{
struct session_state *state = ssh->state;
struct sshenc *enc;
struct sshmac *mac;
struct sshcomp *comp;
struct sshcipher_ctx **ccp;
struct packet_state *ps;
u_int64_t *max_blocks;
const char *wmsg;
int r, crypt_type;
const char *dir = mode == MODE_OUT ? "out" : "in";
debug2_f("mode %d", mode);
if (mode == MODE_OUT) {
ccp = &state->send_context;
crypt_type = CIPHER_ENCRYPT;
ps = &state->p_send;
max_blocks = &state->max_blocks_out;
} else {
ccp = &state->receive_context;
crypt_type = CIPHER_DECRYPT;
ps = &state->p_read;
max_blocks = &state->max_blocks_in;
}
if (state->newkeys[mode] != NULL) {
debug_f("rekeying %s, input %llu bytes %llu blocks, "
"output %llu bytes %llu blocks", dir,
(unsigned long long)state->p_read.bytes,
(unsigned long long)state->p_read.blocks,
(unsigned long long)state->p_send.bytes,
(unsigned long long)state->p_send.blocks);
kex_free_newkeys(state->newkeys[mode]);
state->newkeys[mode] = NULL;
}
/* note that both bytes and the seqnr are not reset */
ps->packets = ps->blocks = 0;
/* move newkeys from kex to state */
if ((state->newkeys[mode] = ssh->kex->newkeys[mode]) == NULL)
return SSH_ERR_INTERNAL_ERROR;
ssh->kex->newkeys[mode] = NULL;
enc = &state->newkeys[mode]->enc;
mac = &state->newkeys[mode]->mac;
comp = &state->newkeys[mode]->comp;
if (cipher_authlen(enc->cipher) == 0) {
if ((r = mac_init(mac)) != 0)
return r;
}
mac->enabled = 1;
DBG(debug_f("cipher_init: %s", dir));
cipher_free(*ccp);
*ccp = NULL;
if ((r = cipher_init(ccp, enc->cipher, enc->key, enc->key_len,
enc->iv, enc->iv_len, crypt_type)) != 0)
return r;
if (!state->cipher_warning_done &&
(wmsg = cipher_warning_message(*ccp)) != NULL) {
error("Warning: %s", wmsg);
state->cipher_warning_done = 1;
}
/* Deleting the keys does not gain extra security */
/* explicit_bzero(enc->iv, enc->block_size);
explicit_bzero(enc->key, enc->key_len);
explicit_bzero(mac->key, mac->key_len); */
if ((comp->type == COMP_ZLIB ||
(comp->type == COMP_DELAYED &&
state->after_authentication)) && comp->enabled == 0) {
if ((r = ssh_packet_init_compression(ssh)) < 0)
return r;
if (mode == MODE_OUT) {
if ((r = start_compression_out(ssh, 6)) != 0)
return r;
} else {
if ((r = start_compression_in(ssh)) != 0)
return r;
}
comp->enabled = 1;
}
/*
* The 2^(blocksize*2) limit is too expensive for 3DES,
* so enforce a 1GB limit for small blocksizes.
* See RFC4344 section 3.2.
*/
if (enc->block_size >= 16)
*max_blocks = (u_int64_t)1 << (enc->block_size*2);
else
*max_blocks = ((u_int64_t)1 << 30) / enc->block_size;
if (state->rekey_limit)
*max_blocks = MINIMUM(*max_blocks,
state->rekey_limit / enc->block_size);
debug("rekey %s after %llu blocks", dir,
(unsigned long long)*max_blocks);
return 0;
}
#define MAX_PACKETS (1U<<31)
static int
ssh_packet_need_rekeying(struct ssh *ssh, u_int outbound_packet_len)
{
struct session_state *state = ssh->state;
u_int32_t out_blocks;
/* XXX client can't cope with rekeying pre-auth */
if (!state->after_authentication)
return 0;
/* Haven't keyed yet or KEX in progress. */
if (ssh_packet_is_rekeying(ssh))
return 0;
/* Peer can't rekey */
if (ssh->compat & SSH_BUG_NOREKEY)
return 0;
/*
* Permit one packet in or out per rekey - this allows us to
* make progress when rekey limits are very small.
*/
if (state->p_send.packets == 0 && state->p_read.packets == 0)
return 0;
/* Time-based rekeying */
if (state->rekey_interval != 0 &&
(int64_t)state->rekey_time + state->rekey_interval <= monotime())
return 1;
/*
* Always rekey when MAX_PACKETS sent in either direction
* As per RFC4344 section 3.1 we do this after 2^31 packets.
*/
if (state->p_send.packets > MAX_PACKETS ||
state->p_read.packets > MAX_PACKETS)
return 1;
/* Rekey after (cipher-specific) maximum blocks */
out_blocks = ROUNDUP(outbound_packet_len,
state->newkeys[MODE_OUT]->enc.block_size);
return (state->max_blocks_out &&
(state->p_send.blocks + out_blocks > state->max_blocks_out)) ||
(state->max_blocks_in &&
(state->p_read.blocks > state->max_blocks_in));
}
int
ssh_packet_check_rekey(struct ssh *ssh)
{
if (!ssh_packet_need_rekeying(ssh, 0))
return 0;
debug3_f("rekex triggered");
return kex_start_rekex(ssh);
}
/*
* Delayed compression for SSH2 is enabled after authentication:
* This happens on the server side after a SSH2_MSG_USERAUTH_SUCCESS is sent,
* and on the client side after a SSH2_MSG_USERAUTH_SUCCESS is received.
*/
static int
ssh_packet_enable_delayed_compress(struct ssh *ssh)
{
struct session_state *state = ssh->state;
struct sshcomp *comp = NULL;
int r, mode;
/*
* Remember that we are past the authentication step, so rekeying
* with COMP_DELAYED will turn on compression immediately.
*/
state->after_authentication = 1;
for (mode = 0; mode < MODE_MAX; mode++) {
/* protocol error: USERAUTH_SUCCESS received before NEWKEYS */
if (state->newkeys[mode] == NULL)
continue;
comp = &state->newkeys[mode]->comp;
if (comp && !comp->enabled && comp->type == COMP_DELAYED) {
if ((r = ssh_packet_init_compression(ssh)) != 0)
return r;
if (mode == MODE_OUT) {
if ((r = start_compression_out(ssh, 6)) != 0)
return r;
} else {
if ((r = start_compression_in(ssh)) != 0)
return r;
}
comp->enabled = 1;
}
}
return 0;
}
/* Used to mute debug logging for noisy packet types */
int
ssh_packet_log_type(u_char type)
{
switch (type) {
case SSH2_MSG_PING:
case SSH2_MSG_PONG:
case SSH2_MSG_CHANNEL_DATA:
case SSH2_MSG_CHANNEL_EXTENDED_DATA:
case SSH2_MSG_CHANNEL_WINDOW_ADJUST:
return 0;
default:
return 1;
}
}
/*
* Finalize packet in SSH2 format (compress, mac, encrypt, enqueue)
*/
int
ssh_packet_send2_wrapped(struct ssh *ssh)
{
struct session_state *state = ssh->state;
u_char type, *cp, macbuf[SSH_DIGEST_MAX_LENGTH];
u_char tmp, padlen, pad = 0;
u_int authlen = 0, aadlen = 0;
u_int len;
struct sshenc *enc = NULL;
struct sshmac *mac = NULL;
struct sshcomp *comp = NULL;
int r, block_size;
if (state->newkeys[MODE_OUT] != NULL) {
enc = &state->newkeys[MODE_OUT]->enc;
mac = &state->newkeys[MODE_OUT]->mac;
comp = &state->newkeys[MODE_OUT]->comp;
/* disable mac for authenticated encryption */
if ((authlen = cipher_authlen(enc->cipher)) != 0)
mac = NULL;
}
block_size = enc ? enc->block_size : 8;
aadlen = (mac && mac->enabled && mac->etm) || authlen ? 4 : 0;
type = (sshbuf_ptr(state->outgoing_packet))[5];
if (ssh_packet_log_type(type))
debug3("send packet: type %u", type);
#ifdef PACKET_DEBUG
fprintf(stderr, "plain: ");
sshbuf_dump(state->outgoing_packet, stderr);
#endif
if (comp && comp->enabled) {
len = sshbuf_len(state->outgoing_packet);
/* skip header, compress only payload */
if ((r = sshbuf_consume(state->outgoing_packet, 5)) != 0)
goto out;
sshbuf_reset(state->compression_buffer);
if ((r = compress_buffer(ssh, state->outgoing_packet,
state->compression_buffer)) != 0)
goto out;
sshbuf_reset(state->outgoing_packet);
if ((r = sshbuf_put(state->outgoing_packet,
"\0\0\0\0\0", 5)) != 0 ||
(r = sshbuf_putb(state->outgoing_packet,
state->compression_buffer)) != 0)
goto out;
DBG(debug("compression: raw %d compressed %zd", len,
sshbuf_len(state->outgoing_packet)));
}
/* sizeof (packet_len + pad_len + payload) */
len = sshbuf_len(state->outgoing_packet);
/*
* calc size of padding, alloc space, get random data,
* minimum padding is 4 bytes
*/
len -= aadlen; /* packet length is not encrypted for EtM modes */
padlen = block_size - (len % block_size);
if (padlen < 4)
padlen += block_size;
if (state->extra_pad) {
tmp = state->extra_pad;
state->extra_pad =
ROUNDUP(state->extra_pad, block_size);
/* check if roundup overflowed */
if (state->extra_pad < tmp)
return SSH_ERR_INVALID_ARGUMENT;
tmp = (len + padlen) % state->extra_pad;
/* Check whether pad calculation below will underflow */
if (tmp > state->extra_pad)
return SSH_ERR_INVALID_ARGUMENT;
pad = state->extra_pad - tmp;
DBG(debug3_f("adding %d (len %d padlen %d extra_pad %d)",
pad, len, padlen, state->extra_pad));
tmp = padlen;
padlen += pad;
/* Check whether padlen calculation overflowed */
if (padlen < tmp)
return SSH_ERR_INVALID_ARGUMENT; /* overflow */
state->extra_pad = 0;
}
if ((r = sshbuf_reserve(state->outgoing_packet, padlen, &cp)) != 0)
goto out;
if (enc && !cipher_ctx_is_plaintext(state->send_context)) {
/* random padding */
arc4random_buf(cp, padlen);
} else {
/* clear padding */
explicit_bzero(cp, padlen);
}
/* sizeof (packet_len + pad_len + payload + padding) */
len = sshbuf_len(state->outgoing_packet);
cp = sshbuf_mutable_ptr(state->outgoing_packet);
if (cp == NULL) {
r = SSH_ERR_INTERNAL_ERROR;
goto out;
}
/* packet_length includes payload, padding and padding length field */
POKE_U32(cp, len - 4);
cp[4] = padlen;
DBG(debug("send: len %d (includes padlen %d, aadlen %d)",
len, padlen, aadlen));
/* compute MAC over seqnr and packet(length fields, payload, padding) */
if (mac && mac->enabled && !mac->etm) {
if ((r = mac_compute(mac, state->p_send.seqnr,
sshbuf_ptr(state->outgoing_packet), len,
macbuf, sizeof(macbuf))) != 0)
goto out;
DBG(debug("done calc MAC out #%d", state->p_send.seqnr));
}
/* encrypt packet and append to output buffer. */
if ((r = sshbuf_reserve(state->output,
sshbuf_len(state->outgoing_packet) + authlen, &cp)) != 0)
goto out;
if ((r = cipher_crypt(state->send_context, state->p_send.seqnr, cp,
sshbuf_ptr(state->outgoing_packet),
len - aadlen, aadlen, authlen)) != 0)
goto out;
/* append unencrypted MAC */
if (mac && mac->enabled) {
if (mac->etm) {
/* EtM: compute mac over aadlen + cipher text */
if ((r = mac_compute(mac, state->p_send.seqnr,
cp, len, macbuf, sizeof(macbuf))) != 0)
goto out;
DBG(debug("done calc MAC(EtM) out #%d",
state->p_send.seqnr));
}
if ((r = sshbuf_put(state->output, macbuf, mac->mac_len)) != 0)
goto out;
}
#ifdef PACKET_DEBUG
fprintf(stderr, "encrypted: ");
sshbuf_dump(state->output, stderr);
#endif
/* increment sequence number for outgoing packets */
if (++state->p_send.seqnr == 0) {
if ((ssh->kex->flags & KEX_INITIAL) != 0) {
ssh_packet_disconnect(ssh, "outgoing sequence number "
"wrapped during initial key exchange");
}
logit("outgoing seqnr wraps around");
}
if (++state->p_send.packets == 0)
if (!(ssh->compat & SSH_BUG_NOREKEY))
return SSH_ERR_NEED_REKEY;
state->p_send.blocks += len / block_size;
state->p_send.bytes += len;
sshbuf_reset(state->outgoing_packet);
if (type == SSH2_MSG_NEWKEYS && ssh->kex->kex_strict) {
debug_f("resetting send seqnr %u", state->p_send.seqnr);
state->p_send.seqnr = 0;
}
if (type == SSH2_MSG_NEWKEYS)
r = ssh_set_newkeys(ssh, MODE_OUT);
else if (type == SSH2_MSG_USERAUTH_SUCCESS && state->server_side)
r = ssh_packet_enable_delayed_compress(ssh);
else
r = 0;
out:
return r;
}
/* returns non-zero if the specified packet type is usec by KEX */
static int
ssh_packet_type_is_kex(u_char type)
{
return
type >= SSH2_MSG_TRANSPORT_MIN &&
type <= SSH2_MSG_TRANSPORT_MAX &&
type != SSH2_MSG_SERVICE_REQUEST &&
type != SSH2_MSG_SERVICE_ACCEPT &&
type != SSH2_MSG_EXT_INFO;
}
int
ssh_packet_send2(struct ssh *ssh)
{
struct session_state *state = ssh->state;
struct packet *p;
u_char type;
int r, need_rekey;
if (sshbuf_len(state->outgoing_packet) < 6)
return SSH_ERR_INTERNAL_ERROR;
type = sshbuf_ptr(state->outgoing_packet)[5];
need_rekey = !ssh_packet_type_is_kex(type) &&
ssh_packet_need_rekeying(ssh, sshbuf_len(state->outgoing_packet));
/*
* During rekeying we can only send key exchange messages.
* Queue everything else.
*/
if ((need_rekey || state->rekeying) && !ssh_packet_type_is_kex(type)) {
if (need_rekey)
debug3_f("rekex triggered");
debug("enqueue packet: %u", type);
p = calloc(1, sizeof(*p));
if (p == NULL)
return SSH_ERR_ALLOC_FAIL;
p->type = type;
p->payload = state->outgoing_packet;
TAILQ_INSERT_TAIL(&state->outgoing, p, next);
state->outgoing_packet = sshbuf_new();
if (state->outgoing_packet == NULL)
return SSH_ERR_ALLOC_FAIL;
if (need_rekey) {
/*
* This packet triggered a rekey, so send the
* KEXINIT now.
* NB. reenters this function via kex_start_rekex().
*/
return kex_start_rekex(ssh);
}
return 0;
}
/* rekeying starts with sending KEXINIT */
if (type == SSH2_MSG_KEXINIT)
state->rekeying = 1;
if ((r = ssh_packet_send2_wrapped(ssh)) != 0)
return r;
/* after a NEWKEYS message we can send the complete queue */
if (type == SSH2_MSG_NEWKEYS) {
state->rekeying = 0;
state->rekey_time = monotime();
while ((p = TAILQ_FIRST(&state->outgoing))) {
type = p->type;
/*
* If this packet triggers a rekex, then skip the
* remaining packets in the queue for now.
* NB. re-enters this function via kex_start_rekex.
*/
if (ssh_packet_need_rekeying(ssh,
sshbuf_len(p->payload))) {
debug3_f("queued packet triggered rekex");
return kex_start_rekex(ssh);
}
debug("dequeue packet: %u", type);
sshbuf_free(state->outgoing_packet);
state->outgoing_packet = p->payload;
TAILQ_REMOVE(&state->outgoing, p, next);
memset(p, 0, sizeof(*p));
free(p);
if ((r = ssh_packet_send2_wrapped(ssh)) != 0)
return r;
}
}
return 0;
}
/*
* Waits until a packet has been received, and returns its type. Note that
* no other data is processed until this returns, so this function should not
* be used during the interactive session.
*/
int
ssh_packet_read_seqnr(struct ssh *ssh, u_char *typep, u_int32_t *seqnr_p)
{
struct session_state *state = ssh->state;
int len, r, ms_remain = 0;
struct pollfd pfd;
char buf[8192];
struct timeval start;
struct timespec timespec, *timespecp = NULL;
DBG(debug("packet_read()"));
/*
* Since we are blocking, ensure that all written packets have
* been sent.
*/
if ((r = ssh_packet_write_wait(ssh)) != 0)
goto out;
/* Stay in the loop until we have received a complete packet. */
for (;;) {
/* Try to read a packet from the buffer. */
if ((r = ssh_packet_read_poll_seqnr(ssh, typep, seqnr_p)) != 0)
break;
/* If we got a packet, return it. */
if (*typep != SSH_MSG_NONE)
break;
/*
* Otherwise, wait for some data to arrive, add it to the
* buffer, and try again.
*/
pfd.fd = state->connection_in;
pfd.events = POLLIN;
if (state->packet_timeout_ms > 0) {
ms_remain = state->packet_timeout_ms;
timespecp = ×pec;
}
/* Wait for some data to arrive. */
for (;;) {
if (state->packet_timeout_ms > 0) {
ms_to_timespec(×pec, ms_remain);
monotime_tv(&start);
}
if ((r = ppoll(&pfd, 1, timespecp, NULL)) >= 0)
break;
if (errno != EAGAIN && errno != EINTR) {
r = SSH_ERR_SYSTEM_ERROR;
goto out;
}
if (state->packet_timeout_ms <= 0)
continue;
ms_subtract_diff(&start, &ms_remain);
if (ms_remain <= 0) {
r = 0;
break;
}
}
if (r == 0) {
r = SSH_ERR_CONN_TIMEOUT;
goto out;
}
/* Read data from the socket. */
len = read(state->connection_in, buf, sizeof(buf));
if (len == 0) {
r = SSH_ERR_CONN_CLOSED;
goto out;
}
if (len == -1) {
r = SSH_ERR_SYSTEM_ERROR;
goto out;
}
/* Append it to the buffer. */
if ((r = ssh_packet_process_incoming(ssh, buf, len)) != 0)
goto out;
}
out:
return r;
}
int
ssh_packet_read(struct ssh *ssh)
{
u_char type;
int r;
if ((r = ssh_packet_read_seqnr(ssh, &type, NULL)) != 0)
fatal_fr(r, "read");
return type;
}
static int
ssh_packet_read_poll2_mux(struct ssh *ssh, u_char *typep, u_int32_t *seqnr_p)
{
struct session_state *state = ssh->state;
const u_char *cp;
size_t need;
int r;
if (ssh->kex)
return SSH_ERR_INTERNAL_ERROR;
*typep = SSH_MSG_NONE;
cp = sshbuf_ptr(state->input);
if (state->packlen == 0) {
if (sshbuf_len(state->input) < 4 + 1)
return 0; /* packet is incomplete */
state->packlen = PEEK_U32(cp);
if (state->packlen < 4 + 1 ||
state->packlen > PACKET_MAX_SIZE)
return SSH_ERR_MESSAGE_INCOMPLETE;
}
need = state->packlen + 4;
if (sshbuf_len(state->input) < need)
return 0; /* packet is incomplete */
sshbuf_reset(state->incoming_packet);
if ((r = sshbuf_put(state->incoming_packet, cp + 4,
state->packlen)) != 0 ||
(r = sshbuf_consume(state->input, need)) != 0 ||
(r = sshbuf_get_u8(state->incoming_packet, NULL)) != 0 ||
(r = sshbuf_get_u8(state->incoming_packet, typep)) != 0)
return r;
if (ssh_packet_log_type(*typep))
debug3_f("type %u", *typep);
/* sshbuf_dump(state->incoming_packet, stderr); */
/* reset for next packet */
state->packlen = 0;
return r;
}
int
ssh_packet_read_poll2(struct ssh *ssh, u_char *typep, u_int32_t *seqnr_p)
{
struct session_state *state = ssh->state;
u_int padlen, need;
u_char *cp;
u_int maclen, aadlen = 0, authlen = 0, block_size;
struct sshenc *enc = NULL;
struct sshmac *mac = NULL;
struct sshcomp *comp = NULL;
int r;
if (state->mux)
return ssh_packet_read_poll2_mux(ssh, typep, seqnr_p);
*typep = SSH_MSG_NONE;
if (state->packet_discard)
return 0;
if (state->newkeys[MODE_IN] != NULL) {
enc = &state->newkeys[MODE_IN]->enc;
mac = &state->newkeys[MODE_IN]->mac;
comp = &state->newkeys[MODE_IN]->comp;
/* disable mac for authenticated encryption */
if ((authlen = cipher_authlen(enc->cipher)) != 0)
mac = NULL;
}
maclen = mac && mac->enabled ? mac->mac_len : 0;
block_size = enc ? enc->block_size : 8;
aadlen = (mac && mac->enabled && mac->etm) || authlen ? 4 : 0;
if (aadlen && state->packlen == 0) {
if (cipher_get_length(state->receive_context,
&state->packlen, state->p_read.seqnr,
sshbuf_ptr(state->input), sshbuf_len(state->input)) != 0)
return 0;
if (state->packlen < 1 + 4 ||
state->packlen > PACKET_MAX_SIZE) {
#ifdef PACKET_DEBUG
sshbuf_dump(state->input, stderr);
#endif
logit("Bad packet length %u.", state->packlen);
if ((r = sshpkt_disconnect(ssh, "Packet corrupt")) != 0)
return r;
return SSH_ERR_CONN_CORRUPT;
}
sshbuf_reset(state->incoming_packet);
} else if (state->packlen == 0) {
/*
* check if input size is less than the cipher block size,
* decrypt first block and extract length of incoming packet
*/
if (sshbuf_len(state->input) < block_size)
return 0;
sshbuf_reset(state->incoming_packet);
if ((r = sshbuf_reserve(state->incoming_packet, block_size,
&cp)) != 0)
goto out;
if ((r = cipher_crypt(state->receive_context,
state->p_send.seqnr, cp, sshbuf_ptr(state->input),
block_size, 0, 0)) != 0)
goto out;
state->packlen = PEEK_U32(sshbuf_ptr(state->incoming_packet));
if (state->packlen < 1 + 4 ||
state->packlen > PACKET_MAX_SIZE) {
#ifdef PACKET_DEBUG
fprintf(stderr, "input: \n");
sshbuf_dump(state->input, stderr);
fprintf(stderr, "incoming_packet: \n");
sshbuf_dump(state->incoming_packet, stderr);
#endif
logit("Bad packet length %u.", state->packlen);
return ssh_packet_start_discard(ssh, enc, mac, 0,
PACKET_MAX_SIZE);
}
if ((r = sshbuf_consume(state->input, block_size)) != 0)
goto out;
}
DBG(debug("input: packet len %u", state->packlen+4));
if (aadlen) {
/* only the payload is encrypted */
need = state->packlen;
} else {
/*
* the payload size and the payload are encrypted, but we
* have a partial packet of block_size bytes
*/
need = 4 + state->packlen - block_size;
}
DBG(debug("partial packet: block %d, need %d, maclen %d, authlen %d,"
" aadlen %d", block_size, need, maclen, authlen, aadlen));
if (need % block_size != 0) {
logit("padding error: need %d block %d mod %d",
need, block_size, need % block_size);
return ssh_packet_start_discard(ssh, enc, mac, 0,
PACKET_MAX_SIZE - block_size);
}
/*
* check if the entire packet has been received and
* decrypt into incoming_packet:
* 'aadlen' bytes are unencrypted, but authenticated.
* 'need' bytes are encrypted, followed by either
* 'authlen' bytes of authentication tag or
* 'maclen' bytes of message authentication code.
*/
if (sshbuf_len(state->input) < aadlen + need + authlen + maclen)
return 0; /* packet is incomplete */
#ifdef PACKET_DEBUG
fprintf(stderr, "read_poll enc/full: ");
sshbuf_dump(state->input, stderr);
#endif
/* EtM: check mac over encrypted input */
if (mac && mac->enabled && mac->etm) {
if ((r = mac_check(mac, state->p_read.seqnr,
sshbuf_ptr(state->input), aadlen + need,
sshbuf_ptr(state->input) + aadlen + need + authlen,
maclen)) != 0) {
if (r == SSH_ERR_MAC_INVALID)
logit("Corrupted MAC on input.");
goto out;
}
}
if ((r = sshbuf_reserve(state->incoming_packet, aadlen + need,
&cp)) != 0)
goto out;
if ((r = cipher_crypt(state->receive_context, state->p_read.seqnr, cp,
sshbuf_ptr(state->input), need, aadlen, authlen)) != 0)
goto out;
if ((r = sshbuf_consume(state->input, aadlen + need + authlen)) != 0)
goto out;
if (mac && mac->enabled) {
/* Not EtM: check MAC over cleartext */
if (!mac->etm && (r = mac_check(mac, state->p_read.seqnr,
sshbuf_ptr(state->incoming_packet),
sshbuf_len(state->incoming_packet),
sshbuf_ptr(state->input), maclen)) != 0) {
if (r != SSH_ERR_MAC_INVALID)
goto out;
logit("Corrupted MAC on input.");
if (need + block_size > PACKET_MAX_SIZE)
return SSH_ERR_INTERNAL_ERROR;
return ssh_packet_start_discard(ssh, enc, mac,
sshbuf_len(state->incoming_packet),
PACKET_MAX_SIZE - need - block_size);
}
/* Remove MAC from input buffer */
DBG(debug("MAC #%d ok", state->p_read.seqnr));
if ((r = sshbuf_consume(state->input, mac->mac_len)) != 0)
goto out;
}
if (seqnr_p != NULL)
*seqnr_p = state->p_read.seqnr;
if (++state->p_read.seqnr == 0) {
if ((ssh->kex->flags & KEX_INITIAL) != 0) {
ssh_packet_disconnect(ssh, "incoming sequence number "
"wrapped during initial key exchange");
}
logit("incoming seqnr wraps around");
}
if (++state->p_read.packets == 0)
if (!(ssh->compat & SSH_BUG_NOREKEY))
return SSH_ERR_NEED_REKEY;
state->p_read.blocks += (state->packlen + 4) / block_size;
state->p_read.bytes += state->packlen + 4;
/* get padlen */
padlen = sshbuf_ptr(state->incoming_packet)[4];
DBG(debug("input: padlen %d", padlen));
if (padlen < 4) {
if ((r = sshpkt_disconnect(ssh,
"Corrupted padlen %d on input.", padlen)) != 0 ||
(r = ssh_packet_write_wait(ssh)) != 0)
return r;
return SSH_ERR_CONN_CORRUPT;
}
/* skip packet size + padlen, discard padding */
if ((r = sshbuf_consume(state->incoming_packet, 4 + 1)) != 0 ||
((r = sshbuf_consume_end(state->incoming_packet, padlen)) != 0))
goto out;
DBG(debug("input: len before de-compress %zd",
sshbuf_len(state->incoming_packet)));
if (comp && comp->enabled) {
sshbuf_reset(state->compression_buffer);
if ((r = uncompress_buffer(ssh, state->incoming_packet,
state->compression_buffer)) != 0)
goto out;
sshbuf_reset(state->incoming_packet);
if ((r = sshbuf_putb(state->incoming_packet,
state->compression_buffer)) != 0)
goto out;
DBG(debug("input: len after de-compress %zd",
sshbuf_len(state->incoming_packet)));
}
/*
* get packet type, implies consume.
* return length of payload (without type field)
*/
if ((r = sshbuf_get_u8(state->incoming_packet, typep)) != 0)
goto out;
if (ssh_packet_log_type(*typep))
debug3("receive packet: type %u", *typep);
if (*typep < SSH2_MSG_MIN) {
if ((r = sshpkt_disconnect(ssh,
"Invalid ssh2 packet type: %d", *typep)) != 0 ||
(r = ssh_packet_write_wait(ssh)) != 0)
return r;
return SSH_ERR_PROTOCOL_ERROR;
}
if (state->hook_in != NULL &&
(r = state->hook_in(ssh, state->incoming_packet, typep,
state->hook_in_ctx)) != 0)
return r;
if (*typep == SSH2_MSG_USERAUTH_SUCCESS && !state->server_side)
r = ssh_packet_enable_delayed_compress(ssh);
else
r = 0;
#ifdef PACKET_DEBUG
fprintf(stderr, "read/plain[%d]:\r\n", *typep);
sshbuf_dump(state->incoming_packet, stderr);
#endif
/* reset for next packet */
state->packlen = 0;
if (*typep == SSH2_MSG_NEWKEYS && ssh->kex->kex_strict) {
debug_f("resetting read seqnr %u", state->p_read.seqnr);
state->p_read.seqnr = 0;
}
if ((r = ssh_packet_check_rekey(ssh)) != 0)
return r;
out:
return r;
}
int
ssh_packet_read_poll_seqnr(struct ssh *ssh, u_char *typep, u_int32_t *seqnr_p)
{
struct session_state *state = ssh->state;
u_int reason, seqnr;
int r;
u_char *msg;
const u_char *d;
size_t len;
for (;;) {
msg = NULL;
r = ssh_packet_read_poll2(ssh, typep, seqnr_p);
if (r != 0)
return r;
if (*typep == 0) {
/* no message ready */
return 0;
}
state->keep_alive_timeouts = 0;
DBG(debug("received packet type %d", *typep));
/* Always process disconnect messages */
if (*typep == SSH2_MSG_DISCONNECT) {
if ((r = sshpkt_get_u32(ssh, &reason)) != 0 ||
(r = sshpkt_get_string(ssh, &msg, NULL)) != 0)
return r;
/* Ignore normal client exit notifications */
do_log2(ssh->state->server_side &&
reason == SSH2_DISCONNECT_BY_APPLICATION ?
SYSLOG_LEVEL_INFO : SYSLOG_LEVEL_ERROR,
"Received disconnect from %s port %d:"
"%u: %.400s", ssh_remote_ipaddr(ssh),
ssh_remote_port(ssh), reason, msg);
free(msg);
return SSH_ERR_DISCONNECTED;
}
/*
* Do not implicitly handle any messages here during initial
* KEX when in strict mode. They will be need to be allowed
* explicitly by the KEX dispatch table or they will generate
* protocol errors.
*/
if (ssh->kex != NULL &&
(ssh->kex->flags & KEX_INITIAL) && ssh->kex->kex_strict)
return 0;
/* Implicitly handle transport-level messages */
switch (*typep) {
case SSH2_MSG_IGNORE:
debug3("Received SSH2_MSG_IGNORE");
break;
case SSH2_MSG_DEBUG:
if ((r = sshpkt_get_u8(ssh, NULL)) != 0 ||
(r = sshpkt_get_string(ssh, &msg, NULL)) != 0 ||
(r = sshpkt_get_string(ssh, NULL, NULL)) != 0) {
free(msg);
return r;
}
debug("Remote: %.900s", msg);
free(msg);
break;
case SSH2_MSG_UNIMPLEMENTED:
if ((r = sshpkt_get_u32(ssh, &seqnr)) != 0)
return r;
debug("Received SSH2_MSG_UNIMPLEMENTED for %u",
seqnr);
break;
case SSH2_MSG_PING:
if ((r = sshpkt_get_string_direct(ssh, &d, &len)) != 0)
return r;
DBG(debug("Received SSH2_MSG_PING len %zu", len));
if ((r = sshpkt_start(ssh, SSH2_MSG_PONG)) != 0 ||
(r = sshpkt_put_string(ssh, d, len)) != 0 ||
(r = sshpkt_send(ssh)) != 0)
return r;
break;
case SSH2_MSG_PONG:
if ((r = sshpkt_get_string_direct(ssh,
NULL, &len)) != 0)
return r;
DBG(debug("Received SSH2_MSG_PONG len %zu", len));
break;
default:
return 0;
}
}
}
/*
* Buffers the supplied input data. This is intended to be used together
* with packet_read_poll().
*/
int
ssh_packet_process_incoming(struct ssh *ssh, const char *buf, u_int len)
{
struct session_state *state = ssh->state;
int r;
if (state->packet_discard) {
state->keep_alive_timeouts = 0; /* ?? */
if (len >= state->packet_discard) {
if ((r = ssh_packet_stop_discard(ssh)) != 0)
return r;
}
state->packet_discard -= len;
return 0;
}
if ((r = sshbuf_put(state->input, buf, len)) != 0)
return r;
return 0;
}
/* Reads and buffers data from the specified fd */
int
ssh_packet_process_read(struct ssh *ssh, int fd)
{
struct session_state *state = ssh->state;
int r;
size_t rlen;
if ((r = sshbuf_read(fd, state->input, PACKET_MAX_SIZE, &rlen)) != 0)
return r;
if (state->packet_discard) {
if ((r = sshbuf_consume_end(state->input, rlen)) != 0)
return r;
state->keep_alive_timeouts = 0; /* ?? */
if (rlen >= state->packet_discard) {
if ((r = ssh_packet_stop_discard(ssh)) != 0)
return r;
}
state->packet_discard -= rlen;
return 0;
}
return 0;
}
int
ssh_packet_remaining(struct ssh *ssh)
{
return sshbuf_len(ssh->state->incoming_packet);
}
/*
* Sends a diagnostic message from the server to the client. This message
* can be sent at any time (but not while constructing another message). The
* message is printed immediately, but only if the client is being executed
* in verbose mode. These messages are primarily intended to ease debugging
* authentication problems. The length of the formatted message must not
* exceed 1024 bytes. This will automatically call ssh_packet_write_wait.
*/
void
ssh_packet_send_debug(struct ssh *ssh, const char *fmt,...)
{
char buf[1024];
va_list args;
int r;
if ((ssh->compat & SSH_BUG_DEBUG))
return;
va_start(args, fmt);
vsnprintf(buf, sizeof(buf), fmt, args);
va_end(args);
debug3("sending debug message: %s", buf);
if ((r = sshpkt_start(ssh, SSH2_MSG_DEBUG)) != 0 ||
(r = sshpkt_put_u8(ssh, 0)) != 0 || /* always display */
(r = sshpkt_put_cstring(ssh, buf)) != 0 ||
(r = sshpkt_put_cstring(ssh, "")) != 0 ||
(r = sshpkt_send(ssh)) != 0 ||
(r = ssh_packet_write_wait(ssh)) != 0)
fatal_fr(r, "send DEBUG");
}
void
sshpkt_fmt_connection_id(struct ssh *ssh, char *s, size_t l)
{
snprintf(s, l, "%.200s%s%s port %d",
ssh->log_preamble ? ssh->log_preamble : "",
ssh->log_preamble ? " " : "",
ssh_remote_ipaddr(ssh), ssh_remote_port(ssh));
}
/*
* Pretty-print connection-terminating errors and exit.
*/
static void
sshpkt_vfatal(struct ssh *ssh, int r, const char *fmt, va_list ap)
{
char *tag = NULL, remote_id[512];
int oerrno = errno;
sshpkt_fmt_connection_id(ssh, remote_id, sizeof(remote_id));
switch (r) {
case SSH_ERR_CONN_CLOSED:
ssh_packet_clear_keys(ssh);
logdie("Connection closed by %s", remote_id);
case SSH_ERR_CONN_TIMEOUT:
ssh_packet_clear_keys(ssh);
logdie("Connection %s %s timed out",
ssh->state->server_side ? "from" : "to", remote_id);
case SSH_ERR_DISCONNECTED:
ssh_packet_clear_keys(ssh);
logdie("Disconnected from %s", remote_id);
case SSH_ERR_SYSTEM_ERROR:
if (errno == ECONNRESET) {
ssh_packet_clear_keys(ssh);
logdie("Connection reset by %s", remote_id);
}
/* FALLTHROUGH */
case SSH_ERR_NO_CIPHER_ALG_MATCH:
case SSH_ERR_NO_MAC_ALG_MATCH:
case SSH_ERR_NO_COMPRESS_ALG_MATCH:
case SSH_ERR_NO_KEX_ALG_MATCH:
case SSH_ERR_NO_HOSTKEY_ALG_MATCH:
if (ssh->kex && ssh->kex->failed_choice) {
ssh_packet_clear_keys(ssh);
errno = oerrno;
logdie("Unable to negotiate with %s: %s. "
"Their offer: %s", remote_id, ssh_err(r),
ssh->kex->failed_choice);
}
/* FALLTHROUGH */
default:
if (vasprintf(&tag, fmt, ap) == -1) {
ssh_packet_clear_keys(ssh);
logdie_f("could not allocate failure message");
}
ssh_packet_clear_keys(ssh);
errno = oerrno;
logdie_r(r, "%s%sConnection %s %s",
tag != NULL ? tag : "", tag != NULL ? ": " : "",
ssh->state->server_side ? "from" : "to", remote_id);
}
}
void
sshpkt_fatal(struct ssh *ssh, int r, const char *fmt, ...)
{
va_list ap;
va_start(ap, fmt);
sshpkt_vfatal(ssh, r, fmt, ap);
/* NOTREACHED */
va_end(ap);
logdie_f("should have exited");
}
/*
* Logs the error plus constructs and sends a disconnect packet, closes the
* connection, and exits. This function never returns. The error message
* should not contain a newline. The length of the formatted message must
* not exceed 1024 bytes.
*/
void
ssh_packet_disconnect(struct ssh *ssh, const char *fmt,...)
{
char buf[1024], remote_id[512];
va_list args;
static int disconnecting = 0;
int r;
if (disconnecting) /* Guard against recursive invocations. */
fatal("packet_disconnect called recursively.");
disconnecting = 1;
/*
* Format the message. Note that the caller must make sure the
* message is of limited size.
*/
sshpkt_fmt_connection_id(ssh, remote_id, sizeof(remote_id));
va_start(args, fmt);
vsnprintf(buf, sizeof(buf), fmt, args);
va_end(args);
/* Display the error locally */
logit("Disconnecting %s: %.100s", remote_id, buf);
/*
* Send the disconnect message to the other side, and wait
* for it to get sent.
*/
if ((r = sshpkt_disconnect(ssh, "%s", buf)) != 0)
sshpkt_fatal(ssh, r, "%s", __func__);
if ((r = ssh_packet_write_wait(ssh)) != 0)
sshpkt_fatal(ssh, r, "%s", __func__);
/* Close the connection. */
ssh_packet_close(ssh);
cleanup_exit(255);
}
/*
* Checks if there is any buffered output, and tries to write some of
* the output.
*/
int
ssh_packet_write_poll(struct ssh *ssh)
{
struct session_state *state = ssh->state;
int len = sshbuf_len(state->output);
int r;
if (len > 0) {
len = write(state->connection_out,
sshbuf_ptr(state->output), len);
if (len == -1) {
if (errno == EINTR || errno == EAGAIN)
return 0;
return SSH_ERR_SYSTEM_ERROR;
}
if (len == 0)
return SSH_ERR_CONN_CLOSED;
if ((r = sshbuf_consume(state->output, len)) != 0)
return r;
}
return 0;
}
/*
* Calls packet_write_poll repeatedly until all pending output data has been
* written.
*/
int
ssh_packet_write_wait(struct ssh *ssh)
{
int ret, r, ms_remain = 0;
struct timeval start;
struct timespec timespec, *timespecp = NULL;
struct session_state *state = ssh->state;
struct pollfd pfd;
if ((r = ssh_packet_write_poll(ssh)) != 0)
return r;
while (ssh_packet_have_data_to_write(ssh)) {
pfd.fd = state->connection_out;
pfd.events = POLLOUT;
if (state->packet_timeout_ms > 0) {
ms_remain = state->packet_timeout_ms;
timespecp = ×pec;
}
for (;;) {
if (state->packet_timeout_ms > 0) {
ms_to_timespec(×pec, ms_remain);
monotime_tv(&start);
}
if ((ret = ppoll(&pfd, 1, timespecp, NULL)) >= 0)
break;
if (errno != EAGAIN && errno != EINTR)
break;
if (state->packet_timeout_ms <= 0)
continue;
ms_subtract_diff(&start, &ms_remain);
if (ms_remain <= 0) {
ret = 0;
break;
}
}
if (ret == 0)
return SSH_ERR_CONN_TIMEOUT;
if ((r = ssh_packet_write_poll(ssh)) != 0)
return r;
}
return 0;
}
/* Returns true if there is buffered data to write to the connection. */
int
ssh_packet_have_data_to_write(struct ssh *ssh)
{
return sshbuf_len(ssh->state->output) != 0;
}
/* Returns true if there is not too much data to write to the connection. */
int
ssh_packet_not_very_much_data_to_write(struct ssh *ssh)
{
if (ssh->state->interactive_mode)
return sshbuf_len(ssh->state->output) < 16384;
else
return sshbuf_len(ssh->state->output) < 128 * 1024;
}
/*
* returns true when there are at most a few keystrokes of data to write
* and the connection is in interactive mode.
*/
int
ssh_packet_interactive_data_to_write(struct ssh *ssh)
{
return ssh->state->interactive_mode &&
sshbuf_len(ssh->state->output) < 256;
}
void
ssh_packet_set_tos(struct ssh *ssh, int tos)
{
if (!ssh_packet_connection_is_on_socket(ssh) || tos == INT_MAX)
return;
set_sock_tos(ssh->state->connection_in, tos);
}
/* Informs that the current session is interactive. Sets IP flags for that. */
void
ssh_packet_set_interactive(struct ssh *ssh, int interactive, int qos_interactive, int qos_bulk)
{
struct session_state *state = ssh->state;
if (state->set_interactive_called)
return;
state->set_interactive_called = 1;
/* Record that we are in interactive mode. */
state->interactive_mode = interactive;
/* Only set socket options if using a socket. */
if (!ssh_packet_connection_is_on_socket(ssh))
return;
set_nodelay(state->connection_in);
ssh_packet_set_tos(ssh, interactive ? qos_interactive : qos_bulk);
}
/* Returns true if the current connection is interactive. */
int
ssh_packet_is_interactive(struct ssh *ssh)
{
return ssh->state->interactive_mode;
}
int
ssh_packet_set_maxsize(struct ssh *ssh, u_int s)
{
struct session_state *state = ssh->state;
if (state->set_maxsize_called) {
logit_f("called twice: old %d new %d",
state->max_packet_size, s);
return -1;
}
if (s < 4 * 1024 || s > 1024 * 1024) {
logit_f("bad size %d", s);
return -1;
}
state->set_maxsize_called = 1;
debug_f("setting to %d", s);
state->max_packet_size = s;
return s;
}
int
ssh_packet_inc_alive_timeouts(struct ssh *ssh)
{
return ++ssh->state->keep_alive_timeouts;
}
void
ssh_packet_set_alive_timeouts(struct ssh *ssh, int ka)
{
ssh->state->keep_alive_timeouts = ka;
}
u_int
ssh_packet_get_maxsize(struct ssh *ssh)
{
return ssh->state->max_packet_size;
}
void
ssh_packet_set_rekey_limits(struct ssh *ssh, u_int64_t bytes, u_int32_t seconds)
{
debug3("rekey after %llu bytes, %u seconds", (unsigned long long)bytes,
(unsigned int)seconds);
ssh->state->rekey_limit = bytes;
ssh->state->rekey_interval = seconds;
}
time_t
ssh_packet_get_rekey_timeout(struct ssh *ssh)
{
time_t seconds;
seconds = ssh->state->rekey_time + ssh->state->rekey_interval -
monotime();
return (seconds <= 0 ? 1 : seconds);
}
void
ssh_packet_set_server(struct ssh *ssh)
{
ssh->state->server_side = 1;
ssh->kex->server = 1; /* XXX unify? */
}
void
ssh_packet_set_authenticated(struct ssh *ssh)
{
ssh->state->after_authentication = 1;
}
void *
ssh_packet_get_input(struct ssh *ssh)
{
return (void *)ssh->state->input;
}
void *
ssh_packet_get_output(struct ssh *ssh)
{
return (void *)ssh->state->output;
}
/* Reset after_authentication and reset compression in post-auth privsep */
static int
ssh_packet_set_postauth(struct ssh *ssh)
{
int r;
debug_f("called");
/* This was set in net child, but is not visible in user child */
ssh->state->after_authentication = 1;
ssh->state->rekeying = 0;
if ((r = ssh_packet_enable_delayed_compress(ssh)) != 0)
return r;
return 0;
}
/* Packet state (de-)serialization for privsep */
/* turn kex into a blob for packet state serialization */
static int
kex_to_blob(struct sshbuf *m, struct kex *kex)
{
int r;
if ((r = sshbuf_put_u32(m, kex->we_need)) != 0 ||
(r = sshbuf_put_cstring(m, kex->hostkey_alg)) != 0 ||
(r = sshbuf_put_u32(m, kex->hostkey_type)) != 0 ||
(r = sshbuf_put_u32(m, kex->hostkey_nid)) != 0 ||
(r = sshbuf_put_u32(m, kex->kex_type)) != 0 ||
(r = sshbuf_put_u32(m, kex->kex_strict)) != 0 ||
(r = sshbuf_put_stringb(m, kex->my)) != 0 ||
(r = sshbuf_put_stringb(m, kex->peer)) != 0 ||
(r = sshbuf_put_stringb(m, kex->client_version)) != 0 ||
(r = sshbuf_put_stringb(m, kex->server_version)) != 0 ||
(r = sshbuf_put_stringb(m, kex->session_id)) != 0 ||
(r = sshbuf_put_u32(m, kex->flags)) != 0)
return r;
return 0;
}
/* turn key exchange results into a blob for packet state serialization */
static int
newkeys_to_blob(struct sshbuf *m, struct ssh *ssh, int mode)
{
struct sshbuf *b;
struct sshcipher_ctx *cc;
struct sshcomp *comp;
struct sshenc *enc;
struct sshmac *mac;
struct newkeys *newkey;
int r;
if ((newkey = ssh->state->newkeys[mode]) == NULL)
return SSH_ERR_INTERNAL_ERROR;
enc = &newkey->enc;
mac = &newkey->mac;
comp = &newkey->comp;
cc = (mode == MODE_OUT) ? ssh->state->send_context :
ssh->state->receive_context;
if ((r = cipher_get_keyiv(cc, enc->iv, enc->iv_len)) != 0)
return r;
if ((b = sshbuf_new()) == NULL)
return SSH_ERR_ALLOC_FAIL;
if ((r = sshbuf_put_cstring(b, enc->name)) != 0 ||
(r = sshbuf_put_u32(b, enc->enabled)) != 0 ||
(r = sshbuf_put_u32(b, enc->block_size)) != 0 ||
(r = sshbuf_put_string(b, enc->key, enc->key_len)) != 0 ||
(r = sshbuf_put_string(b, enc->iv, enc->iv_len)) != 0)
goto out;
if (cipher_authlen(enc->cipher) == 0) {
if ((r = sshbuf_put_cstring(b, mac->name)) != 0 ||
(r = sshbuf_put_u32(b, mac->enabled)) != 0 ||
(r = sshbuf_put_string(b, mac->key, mac->key_len)) != 0)
goto out;
}
if ((r = sshbuf_put_u32(b, comp->type)) != 0 ||
(r = sshbuf_put_cstring(b, comp->name)) != 0)
goto out;
r = sshbuf_put_stringb(m, b);
out:
sshbuf_free(b);
return r;
}
/* serialize packet state into a blob */
int
ssh_packet_get_state(struct ssh *ssh, struct sshbuf *m)
{
struct session_state *state = ssh->state;
int r;
if ((r = kex_to_blob(m, ssh->kex)) != 0 ||
(r = newkeys_to_blob(m, ssh, MODE_OUT)) != 0 ||
(r = newkeys_to_blob(m, ssh, MODE_IN)) != 0 ||
(r = sshbuf_put_u64(m, state->rekey_limit)) != 0 ||
(r = sshbuf_put_u32(m, state->rekey_interval)) != 0 ||
(r = sshbuf_put_u32(m, state->p_send.seqnr)) != 0 ||
(r = sshbuf_put_u64(m, state->p_send.blocks)) != 0 ||
(r = sshbuf_put_u32(m, state->p_send.packets)) != 0 ||
(r = sshbuf_put_u64(m, state->p_send.bytes)) != 0 ||
(r = sshbuf_put_u32(m, state->p_read.seqnr)) != 0 ||
(r = sshbuf_put_u64(m, state->p_read.blocks)) != 0 ||
(r = sshbuf_put_u32(m, state->p_read.packets)) != 0 ||
(r = sshbuf_put_u64(m, state->p_read.bytes)) != 0 ||
(r = sshbuf_put_stringb(m, state->input)) != 0 ||
(r = sshbuf_put_stringb(m, state->output)) != 0)
return r;
return 0;
}
/* restore key exchange results from blob for packet state de-serialization */
static int
newkeys_from_blob(struct sshbuf *m, struct ssh *ssh, int mode)
{
struct sshbuf *b = NULL;
struct sshcomp *comp;
struct sshenc *enc;
struct sshmac *mac;
struct newkeys *newkey = NULL;
size_t keylen, ivlen, maclen;
int r;
if ((newkey = calloc(1, sizeof(*newkey))) == NULL) {
r = SSH_ERR_ALLOC_FAIL;
goto out;
}
if ((r = sshbuf_froms(m, &b)) != 0)
goto out;
#ifdef DEBUG_PK
sshbuf_dump(b, stderr);
#endif
enc = &newkey->enc;
mac = &newkey->mac;
comp = &newkey->comp;
if ((r = sshbuf_get_cstring(b, &enc->name, NULL)) != 0 ||
(r = sshbuf_get_u32(b, (u_int *)&enc->enabled)) != 0 ||
(r = sshbuf_get_u32(b, &enc->block_size)) != 0 ||
(r = sshbuf_get_string(b, &enc->key, &keylen)) != 0 ||
(r = sshbuf_get_string(b, &enc->iv, &ivlen)) != 0)
goto out;
if ((enc->cipher = cipher_by_name(enc->name)) == NULL) {
r = SSH_ERR_INVALID_FORMAT;
goto out;
}
if (cipher_authlen(enc->cipher) == 0) {
if ((r = sshbuf_get_cstring(b, &mac->name, NULL)) != 0)
goto out;
if ((r = mac_setup(mac, mac->name)) != 0)
goto out;
if ((r = sshbuf_get_u32(b, (u_int *)&mac->enabled)) != 0 ||
(r = sshbuf_get_string(b, &mac->key, &maclen)) != 0)
goto out;
if (maclen > mac->key_len) {
r = SSH_ERR_INVALID_FORMAT;
goto out;
}
mac->key_len = maclen;
}
if ((r = sshbuf_get_u32(b, &comp->type)) != 0 ||
(r = sshbuf_get_cstring(b, &comp->name, NULL)) != 0)
goto out;
if (sshbuf_len(b) != 0) {
r = SSH_ERR_INVALID_FORMAT;
goto out;
}
enc->key_len = keylen;
enc->iv_len = ivlen;
ssh->kex->newkeys[mode] = newkey;
newkey = NULL;
r = 0;
out:
free(newkey);
sshbuf_free(b);
return r;
}
/* restore kex from blob for packet state de-serialization */
static int
kex_from_blob(struct sshbuf *m, struct kex **kexp)
{
struct kex *kex;
int r;
if ((kex = kex_new()) == NULL)
return SSH_ERR_ALLOC_FAIL;
if ((r = sshbuf_get_u32(m, &kex->we_need)) != 0 ||
(r = sshbuf_get_cstring(m, &kex->hostkey_alg, NULL)) != 0 ||
(r = sshbuf_get_u32(m, (u_int *)&kex->hostkey_type)) != 0 ||
(r = sshbuf_get_u32(m, (u_int *)&kex->hostkey_nid)) != 0 ||
(r = sshbuf_get_u32(m, &kex->kex_type)) != 0 ||
(r = sshbuf_get_u32(m, &kex->kex_strict)) != 0 ||
(r = sshbuf_get_stringb(m, kex->my)) != 0 ||
(r = sshbuf_get_stringb(m, kex->peer)) != 0 ||
(r = sshbuf_get_stringb(m, kex->client_version)) != 0 ||
(r = sshbuf_get_stringb(m, kex->server_version)) != 0 ||
(r = sshbuf_get_stringb(m, kex->session_id)) != 0 ||
(r = sshbuf_get_u32(m, &kex->flags)) != 0)
goto out;
kex->server = 1;
kex->done = 1;
r = 0;
out:
if (r != 0 || kexp == NULL) {
kex_free(kex);
if (kexp != NULL)
*kexp = NULL;
} else {
kex_free(*kexp);
*kexp = kex;
}
return r;
}
/*
* Restore packet state from content of blob 'm' (de-serialization).
* Note that 'm' will be partially consumed on parsing or any other errors.
*/
int
ssh_packet_set_state(struct ssh *ssh, struct sshbuf *m)
{
struct session_state *state = ssh->state;
const u_char *input, *output;
size_t ilen, olen;
int r;
if ((r = kex_from_blob(m, &ssh->kex)) != 0 ||
(r = newkeys_from_blob(m, ssh, MODE_OUT)) != 0 ||
(r = newkeys_from_blob(m, ssh, MODE_IN)) != 0 ||
(r = sshbuf_get_u64(m, &state->rekey_limit)) != 0 ||
(r = sshbuf_get_u32(m, &state->rekey_interval)) != 0 ||
(r = sshbuf_get_u32(m, &state->p_send.seqnr)) != 0 ||
(r = sshbuf_get_u64(m, &state->p_send.blocks)) != 0 ||
(r = sshbuf_get_u32(m, &state->p_send.packets)) != 0 ||
(r = sshbuf_get_u64(m, &state->p_send.bytes)) != 0 ||
(r = sshbuf_get_u32(m, &state->p_read.seqnr)) != 0 ||
(r = sshbuf_get_u64(m, &state->p_read.blocks)) != 0 ||
(r = sshbuf_get_u32(m, &state->p_read.packets)) != 0 ||
(r = sshbuf_get_u64(m, &state->p_read.bytes)) != 0)
return r;
/*
* We set the time here so that in post-auth privsep child we
* count from the completion of the authentication.
*/
state->rekey_time = monotime();
/* XXX ssh_set_newkeys overrides p_read.packets? XXX */
if ((r = ssh_set_newkeys(ssh, MODE_IN)) != 0 ||
(r = ssh_set_newkeys(ssh, MODE_OUT)) != 0)
return r;
if ((r = ssh_packet_set_postauth(ssh)) != 0)
return r;
sshbuf_reset(state->input);
sshbuf_reset(state->output);
if ((r = sshbuf_get_string_direct(m, &input, &ilen)) != 0 ||
(r = sshbuf_get_string_direct(m, &output, &olen)) != 0 ||
(r = sshbuf_put(state->input, input, ilen)) != 0 ||
(r = sshbuf_put(state->output, output, olen)) != 0)
return r;
if (sshbuf_len(m))
return SSH_ERR_INVALID_FORMAT;
debug3_f("done");
return 0;
}
/* NEW API */
/* put data to the outgoing packet */
int
sshpkt_put(struct ssh *ssh, const void *v, size_t len)
{
return sshbuf_put(ssh->state->outgoing_packet, v, len);
}
int
sshpkt_putb(struct ssh *ssh, const struct sshbuf *b)
{
return sshbuf_putb(ssh->state->outgoing_packet, b);
}
int
sshpkt_put_u8(struct ssh *ssh, u_char val)
{
return sshbuf_put_u8(ssh->state->outgoing_packet, val);
}
int
sshpkt_put_u32(struct ssh *ssh, u_int32_t val)
{
return sshbuf_put_u32(ssh->state->outgoing_packet, val);
}
int
sshpkt_put_u64(struct ssh *ssh, u_int64_t val)
{
return sshbuf_put_u64(ssh->state->outgoing_packet, val);
}
int
sshpkt_put_string(struct ssh *ssh, const void *v, size_t len)
{
return sshbuf_put_string(ssh->state->outgoing_packet, v, len);
}
int
sshpkt_put_cstring(struct ssh *ssh, const void *v)
{
return sshbuf_put_cstring(ssh->state->outgoing_packet, v);
}
int
sshpkt_put_stringb(struct ssh *ssh, const struct sshbuf *v)
{
return sshbuf_put_stringb(ssh->state->outgoing_packet, v);
}
#ifdef WITH_OPENSSL
int
sshpkt_put_ec(struct ssh *ssh, const EC_POINT *v, const EC_GROUP *g)
{
return sshbuf_put_ec(ssh->state->outgoing_packet, v, g);
}
int
sshpkt_put_bignum2(struct ssh *ssh, const BIGNUM *v)
{
return sshbuf_put_bignum2(ssh->state->outgoing_packet, v);
}
#endif /* WITH_OPENSSL */
/* fetch data from the incoming packet */
int
sshpkt_get(struct ssh *ssh, void *valp, size_t len)
{
return sshbuf_get(ssh->state->incoming_packet, valp, len);
}
int
sshpkt_get_u8(struct ssh *ssh, u_char *valp)
{
return sshbuf_get_u8(ssh->state->incoming_packet, valp);
}
int
sshpkt_get_u32(struct ssh *ssh, u_int32_t *valp)
{
return sshbuf_get_u32(ssh->state->incoming_packet, valp);
}
int
sshpkt_get_u64(struct ssh *ssh, u_int64_t *valp)
{
return sshbuf_get_u64(ssh->state->incoming_packet, valp);
}
int
sshpkt_get_string(struct ssh *ssh, u_char **valp, size_t *lenp)
{
return sshbuf_get_string(ssh->state->incoming_packet, valp, lenp);
}
int
sshpkt_get_string_direct(struct ssh *ssh, const u_char **valp, size_t *lenp)
{
return sshbuf_get_string_direct(ssh->state->incoming_packet, valp, lenp);
}
int
sshpkt_peek_string_direct(struct ssh *ssh, const u_char **valp, size_t *lenp)
{
return sshbuf_peek_string_direct(ssh->state->incoming_packet, valp, lenp);
}
int
sshpkt_get_cstring(struct ssh *ssh, char **valp, size_t *lenp)
{
return sshbuf_get_cstring(ssh->state->incoming_packet, valp, lenp);
}
int
sshpkt_getb_froms(struct ssh *ssh, struct sshbuf **valp)
{
return sshbuf_froms(ssh->state->incoming_packet, valp);
}
#ifdef WITH_OPENSSL
int
sshpkt_get_ec(struct ssh *ssh, EC_POINT *v, const EC_GROUP *g)
{
return sshbuf_get_ec(ssh->state->incoming_packet, v, g);
}
int
sshpkt_get_bignum2(struct ssh *ssh, BIGNUM **valp)
{
return sshbuf_get_bignum2(ssh->state->incoming_packet, valp);
}
#endif /* WITH_OPENSSL */
int
sshpkt_get_end(struct ssh *ssh)
{
if (sshbuf_len(ssh->state->incoming_packet) > 0)
return SSH_ERR_UNEXPECTED_TRAILING_DATA;
return 0;
}
const u_char *
sshpkt_ptr(struct ssh *ssh, size_t *lenp)
{
if (lenp != NULL)
*lenp = sshbuf_len(ssh->state->incoming_packet);
return sshbuf_ptr(ssh->state->incoming_packet);
}
/* start a new packet */
int
sshpkt_start(struct ssh *ssh, u_char type)
{
u_char buf[6]; /* u32 packet length, u8 pad len, u8 type */
DBG(debug("packet_start[%d]", type));
memset(buf, 0, sizeof(buf));
buf[sizeof(buf) - 1] = type;
sshbuf_reset(ssh->state->outgoing_packet);
return sshbuf_put(ssh->state->outgoing_packet, buf, sizeof(buf));
}
static int
ssh_packet_send_mux(struct ssh *ssh)
{
struct session_state *state = ssh->state;
u_char type, *cp;
size_t len;
int r;
if (ssh->kex)
return SSH_ERR_INTERNAL_ERROR;
len = sshbuf_len(state->outgoing_packet);
if (len < 6)
return SSH_ERR_INTERNAL_ERROR;
cp = sshbuf_mutable_ptr(state->outgoing_packet);
type = cp[5];
if (ssh_packet_log_type(type))
debug3_f("type %u", type);
/* drop everything, but the connection protocol */
if (type >= SSH2_MSG_CONNECTION_MIN &&
type <= SSH2_MSG_CONNECTION_MAX) {
POKE_U32(cp, len - 4);
if ((r = sshbuf_putb(state->output,
state->outgoing_packet)) != 0)
return r;
/* sshbuf_dump(state->output, stderr); */
}
sshbuf_reset(state->outgoing_packet);
return 0;
}
/*
* 9.2. Ignored Data Message
*
* byte SSH_MSG_IGNORE
* string data
*
* All implementations MUST understand (and ignore) this message at any
* time (after receiving the protocol version). No implementation is
* required to send them. This message can be used as an additional
* protection measure against advanced traffic analysis techniques.
*/
int
sshpkt_msg_ignore(struct ssh *ssh, u_int nbytes)
{
u_int32_t rnd = 0;
int r;
u_int i;
if ((r = sshpkt_start(ssh, SSH2_MSG_IGNORE)) != 0 ||
(r = sshpkt_put_u32(ssh, nbytes)) != 0)
return r;
for (i = 0; i < nbytes; i++) {
if (i % 4 == 0)
rnd = arc4random();
if ((r = sshpkt_put_u8(ssh, (u_char)rnd & 0xff)) != 0)
return r;
rnd >>= 8;
}
return 0;
}
/* send it */
int
sshpkt_send(struct ssh *ssh)
{
if (ssh->state && ssh->state->mux)
return ssh_packet_send_mux(ssh);
return ssh_packet_send2(ssh);
}
int
sshpkt_disconnect(struct ssh *ssh, const char *fmt,...)
{
char buf[1024];
va_list args;
int r;
va_start(args, fmt);
vsnprintf(buf, sizeof(buf), fmt, args);
va_end(args);
debug2_f("sending SSH2_MSG_DISCONNECT: %s", buf);
if ((r = sshpkt_start(ssh, SSH2_MSG_DISCONNECT)) != 0 ||
(r = sshpkt_put_u32(ssh, SSH2_DISCONNECT_PROTOCOL_ERROR)) != 0 ||
(r = sshpkt_put_cstring(ssh, buf)) != 0 ||
(r = sshpkt_put_cstring(ssh, "")) != 0 ||
(r = sshpkt_send(ssh)) != 0)
return r;
return 0;
}
/* roundup current message to pad bytes */
int
sshpkt_add_padding(struct ssh *ssh, u_char pad)
{
ssh->state->extra_pad = pad;
return 0;
}
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