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openssh-portable/packet.c

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/* $OpenBSD: packet.c,v 1.197 2014/06/24 01:13:21 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 "includes.h"
#include <sys/types.h>
#include "openbsd-compat/sys-queue.h"
#include <sys/param.h>
#include <sys/socket.h>
#ifdef HAVE_SYS_TIME_H
# include <sys/time.h>
#endif
#include <netinet/in.h>
#include <netinet/ip.h>
#include <arpa/inet.h>
#include <errno.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <signal.h>
#include <time.h>
#include "xmalloc.h"
#include "buffer.h"
#include "packet.h"
#include "crc32.h"
#include "compress.h"
#include "deattack.h"
#include "channels.h"
#include "compat.h"
#include "ssh1.h"
#include "ssh2.h"
#include "cipher.h"
#include "key.h"
#include "kex.h"
#include "mac.h"
#include "log.h"
#include "canohost.h"
#include "misc.h"
#include "ssh.h"
#include "ssherr.h"
#include "roaming.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;
Buffer 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. */
CipherContext receive_context;
/* Encryption context for sending data. Only used for encryption. */
CipherContext send_context;
/* Buffer for raw input data from the socket. */
Buffer input;
/* Buffer for raw output data going to the socket. */
Buffer output;
/* Buffer for the partial outgoing packet being constructed. */
Buffer outgoing_packet;
/* Buffer for the incoming packet currently being processed. */
Buffer incoming_packet;
/* Scratch buffer for packet compression/decompression. */
Buffer compression_buffer;
int compression_buffer_ready;
/*
* Flag indicating whether packet compression/decompression is
* enabled.
*/
int packet_compression;
/* 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 */
Newkeys *newkeys[MODE_MAX];
struct packet_state p_read, p_send;
/* Volume-based rekeying */
u_int64_t max_blocks_in, max_blocks_out;
u_int32_t rekey_limit;
/* Time-based rekeying */
time_t rekey_interval; /* how often in seconds */
time_t rekey_time; /* time of last rekeying */
/* Session key for protocol v1 */
u_char ssh1_key[SSH_SESSION_KEY_LENGTH];
u_int ssh1_keylen;
/* roundup current message to extra_pad bytes */
u_char extra_pad;
/* XXX discard incoming data after MAC error */
u_int packet_discard;
Mac *packet_discard_mac;
/* Used in packet_read_poll2() */
u_int packlen;
/* Used in packet_send2 */
int rekeying;
/* Used in packet_set_interactive */
int set_interactive_called;
/* Used in packet_set_maxsize */
int set_maxsize_called;
TAILQ_HEAD(, packet) outgoing;
};
static struct session_state *active_state, *backup_state;
static struct session_state *
alloc_session_state(void)
{
struct session_state *s = xcalloc(1, sizeof(*s));
s->connection_in = -1;
s->connection_out = -1;
s->max_packet_size = 32768;
s->packet_timeout_ms = -1;
return s;
}
/*
* Sets the descriptors used for communication. Disables encryption until
* packet_set_encryption_key is called.
*/
void
packet_set_connection(int fd_in, int fd_out)
{
const Cipher *none = cipher_by_name("none");
int r;
if (none == NULL)
fatal("packet_set_connection: cannot load cipher 'none'");
if (active_state == NULL)
active_state = alloc_session_state();
active_state->connection_in = fd_in;
active_state->connection_out = fd_out;
if ((r = cipher_init(&active_state->send_context, none,
(const u_char *)"", 0, NULL, 0, CIPHER_ENCRYPT)) != 0 ||
(r = cipher_init(&active_state->receive_context, none,
(const u_char *)"", 0, NULL, 0, CIPHER_DECRYPT)) != 0)
fatal("%s: cipher_init: %s", __func__, ssh_err(r));
active_state->newkeys[MODE_IN] = active_state->newkeys[MODE_OUT] = NULL;
if (!active_state->initialized) {
active_state->initialized = 1;
buffer_init(&active_state->input);
buffer_init(&active_state->output);
buffer_init(&active_state->outgoing_packet);
buffer_init(&active_state->incoming_packet);
TAILQ_INIT(&active_state->outgoing);
active_state->p_send.packets = active_state->p_read.packets = 0;
}
}
void
packet_set_timeout(int timeout, int count)
{
if (timeout <= 0 || count <= 0) {
active_state->packet_timeout_ms = -1;
return;
}
if ((INT_MAX / 1000) / count < timeout)
active_state->packet_timeout_ms = INT_MAX;
else
active_state->packet_timeout_ms = timeout * count * 1000;
}
static void
packet_stop_discard(void)
{
if (active_state->packet_discard_mac) {
char buf[1024];
memset(buf, 'a', sizeof(buf));
while (buffer_len(&active_state->incoming_packet) <
PACKET_MAX_SIZE)
buffer_append(&active_state->incoming_packet, buf,
sizeof(buf));
(void) mac_compute(active_state->packet_discard_mac,
active_state->p_read.seqnr,
buffer_ptr(&active_state->incoming_packet),
PACKET_MAX_SIZE);
}
logit("Finished discarding for %.200s", get_remote_ipaddr());
cleanup_exit(255);
}
static void
packet_start_discard(Enc *enc, Mac *mac, u_int packet_length, u_int discard)
{
if (enc == NULL || !cipher_is_cbc(enc->cipher) || (mac && mac->etm))
packet_disconnect("Packet corrupt");
if (packet_length != PACKET_MAX_SIZE && mac && mac->enabled)
active_state->packet_discard_mac = mac;
if (buffer_len(&active_state->input) >= discard)
packet_stop_discard();
active_state->packet_discard = discard -
buffer_len(&active_state->input);
}
/* Returns 1 if remote host is connected via socket, 0 if not. */
int
packet_connection_is_on_socket(void)
{
struct sockaddr_storage from, to;
socklen_t fromlen, tolen;
/* filedescriptors in and out are the same, so it's a socket */
if (active_state->connection_in == active_state->connection_out)
return 1;
fromlen = sizeof(from);
memset(&from, 0, sizeof(from));
if (getpeername(active_state->connection_in, (struct sockaddr *)&from,
&fromlen) < 0)
return 0;
tolen = sizeof(to);
memset(&to, 0, sizeof(to));
if (getpeername(active_state->connection_out, (struct sockaddr *)&to,
&tolen) < 0)
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;
}
/*
* Exports an IV from the CipherContext required to export the key
* state back from the unprivileged child to the privileged parent
* process.
*/
void
packet_get_keyiv(int mode, u_char *iv, u_int len)
{
CipherContext *cc;
int r;
if (mode == MODE_OUT)
cc = &active_state->send_context;
else
cc = &active_state->receive_context;
if ((r = cipher_get_keyiv(cc, iv, len)) != 0)
fatal("%s: cipher_get_keyiv: %s", __func__, ssh_err(r));
}
int
packet_get_keycontext(int mode, u_char *dat)
{
CipherContext *cc;
if (mode == MODE_OUT)
cc = &active_state->send_context;
else
cc = &active_state->receive_context;
return (cipher_get_keycontext(cc, dat));
}
void
packet_set_keycontext(int mode, u_char *dat)
{
CipherContext *cc;
if (mode == MODE_OUT)
cc = &active_state->send_context;
else
cc = &active_state->receive_context;
cipher_set_keycontext(cc, dat);
}
int
packet_get_keyiv_len(int mode)
{
CipherContext *cc;
if (mode == MODE_OUT)
cc = &active_state->send_context;
else
cc = &active_state->receive_context;
return (cipher_get_keyiv_len(cc));
}
void
packet_set_iv(int mode, u_char *dat)
{
CipherContext *cc;
int r;
if (mode == MODE_OUT)
cc = &active_state->send_context;
else
cc = &active_state->receive_context;
if ((r = cipher_set_keyiv(cc, dat)) != 0)
fatal("%s: cipher_set_keyiv: %s", __func__, ssh_err(r));
}
int
packet_get_ssh1_cipher(void)
{
return (cipher_get_number(active_state->receive_context.cipher));
}
void
packet_get_state(int mode, u_int32_t *seqnr, u_int64_t *blocks,
u_int32_t *packets, u_int64_t *bytes)
{
struct packet_state *state;
state = (mode == MODE_IN) ?
&active_state->p_read : &active_state->p_send;
if (seqnr)
*seqnr = state->seqnr;
if (blocks)
*blocks = state->blocks;
if (packets)
*packets = state->packets;
if (bytes)
*bytes = state->bytes;
}
void
packet_set_state(int mode, u_int32_t seqnr, u_int64_t blocks, u_int32_t packets,
u_int64_t bytes)
{
struct packet_state *state;
state = (mode == MODE_IN) ?
&active_state->p_read : &active_state->p_send;
state->seqnr = seqnr;
state->blocks = blocks;
state->packets = packets;
state->bytes = bytes;
}
static int
packet_connection_af(void)
{
struct sockaddr_storage to;
socklen_t tolen = sizeof(to);
memset(&to, 0, sizeof(to));
if (getsockname(active_state->connection_out, (struct sockaddr *)&to,
&tolen) < 0)
return 0;
#ifdef IPV4_IN_IPV6
if (to.ss_family == AF_INET6 &&
IN6_IS_ADDR_V4MAPPED(&((struct sockaddr_in6 *)&to)->sin6_addr))
return AF_INET;
#endif
return to.ss_family;
}
/* Sets the connection into non-blocking mode. */
void
packet_set_nonblocking(void)
{
/* Set the socket into non-blocking mode. */
set_nonblock(active_state->connection_in);
if (active_state->connection_out != active_state->connection_in)
set_nonblock(active_state->connection_out);
}
/* Returns the socket used for reading. */
int
packet_get_connection_in(void)
{
return active_state->connection_in;
}
/* Returns the descriptor used for writing. */
int
packet_get_connection_out(void)
{
return active_state->connection_out;
}
/* Closes the connection and clears and frees internal data structures. */
void
packet_close(void)
{
if (!active_state->initialized)
return;
active_state->initialized = 0;
if (active_state->connection_in == active_state->connection_out) {
shutdown(active_state->connection_out, SHUT_RDWR);
close(active_state->connection_out);
} else {
close(active_state->connection_in);
close(active_state->connection_out);
}
buffer_free(&active_state->input);
buffer_free(&active_state->output);
buffer_free(&active_state->outgoing_packet);
buffer_free(&active_state->incoming_packet);
if (active_state->compression_buffer_ready) {
buffer_free(&active_state->compression_buffer);
buffer_compress_uninit();
}
cipher_cleanup(&active_state->send_context);
cipher_cleanup(&active_state->receive_context);
}
/* Sets remote side protocol flags. */
void
packet_set_protocol_flags(u_int protocol_flags)
{
active_state->remote_protocol_flags = protocol_flags;
}
/* Returns the remote protocol flags set earlier by the above function. */
u_int
packet_get_protocol_flags(void)
{
return active_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 void
packet_init_compression(void)
{
if (active_state->compression_buffer_ready == 1)
return;
active_state->compression_buffer_ready = 1;
buffer_init(&active_state->compression_buffer);
}
void
packet_start_compression(int level)
{
if (active_state->packet_compression && !compat20)
fatal("Compression already enabled.");
active_state->packet_compression = 1;
packet_init_compression();
buffer_compress_init_send(level);
buffer_compress_init_recv();
}
/*
* Causes any further packets to be encrypted using the given key. The same
* key is used for both sending and reception. However, both directions are
* encrypted independently of each other.
*/
void
packet_set_encryption_key(const u_char *key, u_int keylen, int number)
{
const Cipher *cipher = cipher_by_number(number);
int r;
if (cipher == NULL)
fatal("packet_set_encryption_key: unknown cipher number %d", number);
if (keylen < 20)
fatal("packet_set_encryption_key: keylen too small: %d", keylen);
if (keylen > SSH_SESSION_KEY_LENGTH)
fatal("packet_set_encryption_key: keylen too big: %d", keylen);
memcpy(active_state->ssh1_key, key, keylen);
active_state->ssh1_keylen = keylen;
if ((r = cipher_init(&active_state->send_context, cipher,
key, keylen, NULL, 0, CIPHER_ENCRYPT)) != 0 ||
(r = cipher_init(&active_state->receive_context, cipher,
key, keylen, NULL, 0, CIPHER_DECRYPT)) != 0)
fatal("%s: cipher_init: %s", __func__, ssh_err(r));
}
u_int
packet_get_encryption_key(u_char *key)
{
if (key == NULL)
return (active_state->ssh1_keylen);
memcpy(key, active_state->ssh1_key, active_state->ssh1_keylen);
return (active_state->ssh1_keylen);
}
/* Start constructing a packet to send. */
void
packet_start(u_char type)
{
u_char buf[9];
int len;
DBG(debug("packet_start[%d]", type));
len = compat20 ? 6 : 9;
memset(buf, 0, len - 1);
buf[len - 1] = type;
buffer_clear(&active_state->outgoing_packet);
buffer_append(&active_state->outgoing_packet, buf, len);
}
/* Append payload. */
void
packet_put_char(int value)
{
char ch = value;
buffer_append(&active_state->outgoing_packet, &ch, 1);
}
void
packet_put_int(u_int value)
{
buffer_put_int(&active_state->outgoing_packet, value);
}
void
packet_put_int64(u_int64_t value)
{
buffer_put_int64(&active_state->outgoing_packet, value);
}
void
packet_put_string(const void *buf, u_int len)
{
buffer_put_string(&active_state->outgoing_packet, buf, len);
}
void
packet_put_cstring(const char *str)
{
buffer_put_cstring(&active_state->outgoing_packet, str);
}
void
packet_put_raw(const void *buf, u_int len)
{
buffer_append(&active_state->outgoing_packet, buf, len);
}
#ifdef WITH_OPENSSL
void
packet_put_bignum(BIGNUM * value)
{
buffer_put_bignum(&active_state->outgoing_packet, value);
}
void
packet_put_bignum2(BIGNUM * value)
{
buffer_put_bignum2(&active_state->outgoing_packet, value);
}
#endif
#ifdef OPENSSL_HAS_ECC
void
packet_put_ecpoint(const EC_GROUP *curve, const EC_POINT *point)
{
buffer_put_ecpoint(&active_state->outgoing_packet, curve, point);
}
#endif
/*
* Finalizes and sends the packet. If the encryption key has been set,
* encrypts the packet before sending.
*/
static void
packet_send1(void)
{
u_char buf[8], *cp;
int i, padding, len;
u_int checksum;
u_int32_t rnd = 0;
/*
* If using packet compression, compress the payload of the outgoing
* packet.
*/
if (active_state->packet_compression) {
buffer_clear(&active_state->compression_buffer);
/* Skip padding. */
buffer_consume(&active_state->outgoing_packet, 8);
/* padding */
buffer_append(&active_state->compression_buffer,
"\0\0\0\0\0\0\0\0", 8);
buffer_compress(&active_state->outgoing_packet,
&active_state->compression_buffer);
buffer_clear(&active_state->outgoing_packet);
buffer_append(&active_state->outgoing_packet,
buffer_ptr(&active_state->compression_buffer),
buffer_len(&active_state->compression_buffer));
}
/* Compute packet length without padding (add checksum, remove padding). */
len = buffer_len(&active_state->outgoing_packet) + 4 - 8;
/* Insert padding. Initialized to zero in packet_start1() */
padding = 8 - len % 8;
if (!active_state->send_context.plaintext) {
cp = buffer_ptr(&active_state->outgoing_packet);
for (i = 0; i < padding; i++) {
if (i % 4 == 0)
rnd = arc4random();
cp[7 - i] = rnd & 0xff;
rnd >>= 8;
}
}
buffer_consume(&active_state->outgoing_packet, 8 - padding);
/* Add check bytes. */
checksum = ssh_crc32(buffer_ptr(&active_state->outgoing_packet),
buffer_len(&active_state->outgoing_packet));
put_u32(buf, checksum);
buffer_append(&active_state->outgoing_packet, buf, 4);
#ifdef PACKET_DEBUG
fprintf(stderr, "packet_send plain: ");
buffer_dump(&active_state->outgoing_packet);
#endif
/* Append to output. */
put_u32(buf, len);
buffer_append(&active_state->output, buf, 4);
cp = buffer_append_space(&active_state->output,
buffer_len(&active_state->outgoing_packet));
if (cipher_crypt(&active_state->send_context, 0, cp,
buffer_ptr(&active_state->outgoing_packet),
buffer_len(&active_state->outgoing_packet), 0, 0) != 0)
fatal("%s: cipher_crypt failed", __func__);
#ifdef PACKET_DEBUG
fprintf(stderr, "encrypted: ");
buffer_dump(&active_state->output);
#endif
active_state->p_send.packets++;
active_state->p_send.bytes += len +
buffer_len(&active_state->outgoing_packet);
buffer_clear(&active_state->outgoing_packet);
/*
* Note that the packet is now only buffered in output. It won't be
* actually sent until packet_write_wait or packet_write_poll is
* called.
*/
}
void
set_newkeys(int mode)
{
Enc *enc;
Mac *mac;
Comp *comp;
CipherContext *cc;
u_int64_t *max_blocks;
int r, crypt_type;
debug2("set_newkeys: mode %d", mode);
if (mode == MODE_OUT) {
cc = &active_state->send_context;
crypt_type = CIPHER_ENCRYPT;
active_state->p_send.packets = active_state->p_send.blocks = 0;
max_blocks = &active_state->max_blocks_out;
} else {
cc = &active_state->receive_context;
crypt_type = CIPHER_DECRYPT;
active_state->p_read.packets = active_state->p_read.blocks = 0;
max_blocks = &active_state->max_blocks_in;
}
if (active_state->newkeys[mode] != NULL) {
debug("set_newkeys: rekeying");
cipher_cleanup(cc);
enc = &active_state->newkeys[mode]->enc;
mac = &active_state->newkeys[mode]->mac;
comp = &active_state->newkeys[mode]->comp;
mac_clear(mac);
explicit_bzero(enc->iv, enc->iv_len);
explicit_bzero(enc->key, enc->key_len);
explicit_bzero(mac->key, mac->key_len);
free(enc->name);
free(enc->iv);
free(enc->key);
free(mac->name);
free(mac->key);
free(comp->name);
free(active_state->newkeys[mode]);
}
active_state->newkeys[mode] = kex_get_newkeys(mode);
if (active_state->newkeys[mode] == NULL)
fatal("newkeys: no keys for mode %d", mode);
enc = &active_state->newkeys[mode]->enc;
mac = &active_state->newkeys[mode]->mac;
comp = &active_state->newkeys[mode]->comp;
if (cipher_authlen(enc->cipher) == 0 && mac_init(mac) == 0)
mac->enabled = 1;
DBG(debug("cipher_init_context: %d", mode));
if ((r = cipher_init(cc, enc->cipher, enc->key, enc->key_len,
enc->iv, enc->iv_len, crypt_type)) != 0)
fatal("%s: cipher_init: %s", __func__, ssh_err(r));
/* 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 &&
active_state->after_authentication)) && comp->enabled == 0) {
packet_init_compression();
if (mode == MODE_OUT)
buffer_compress_init_send(6);
else
buffer_compress_init_recv();
comp->enabled = 1;
}
/*
* The 2^(blocksize*2) limit is too expensive for 3DES,
* blowfish, etc, so enforce a 1GB limit for small blocksizes.
*/
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 (active_state->rekey_limit)
*max_blocks = MIN(*max_blocks,
active_state->rekey_limit / enc->block_size);
}
/*
* 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 void
packet_enable_delayed_compress(void)
{
Comp *comp = NULL;
int mode;
/*
* Remember that we are past the authentication step, so rekeying
* with COMP_DELAYED will turn on compression immediately.
*/
active_state->after_authentication = 1;
for (mode = 0; mode < MODE_MAX; mode++) {
/* protocol error: USERAUTH_SUCCESS received before NEWKEYS */
if (active_state->newkeys[mode] == NULL)
continue;
comp = &active_state->newkeys[mode]->comp;
if (comp && !comp->enabled && comp->type == COMP_DELAYED) {
packet_init_compression();
if (mode == MODE_OUT)
buffer_compress_init_send(6);
else
buffer_compress_init_recv();
comp->enabled = 1;
}
}
}
/*
* Finalize packet in SSH2 format (compress, mac, encrypt, enqueue)
*/
static void
packet_send2_wrapped(void)
{
u_char type, *cp, *macbuf = NULL;
u_char padlen, pad = 0;
u_int i, len, authlen = 0, aadlen = 0;
u_int32_t rnd = 0;
Enc *enc = NULL;
Mac *mac = NULL;
Comp *comp = NULL;
int block_size;
if (active_state->newkeys[MODE_OUT] != NULL) {
enc = &active_state->newkeys[MODE_OUT]->enc;
mac = &active_state->newkeys[MODE_OUT]->mac;
comp = &active_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;
cp = buffer_ptr(&active_state->outgoing_packet);
type = cp[5];
#ifdef PACKET_DEBUG
fprintf(stderr, "plain: ");
buffer_dump(&active_state->outgoing_packet);
#endif
if (comp && comp->enabled) {
len = buffer_len(&active_state->outgoing_packet);
/* skip header, compress only payload */
buffer_consume(&active_state->outgoing_packet, 5);
buffer_clear(&active_state->compression_buffer);
buffer_compress(&active_state->outgoing_packet,
&active_state->compression_buffer);
buffer_clear(&active_state->outgoing_packet);
buffer_append(&active_state->outgoing_packet, "\0\0\0\0\0", 5);
buffer_append(&active_state->outgoing_packet,
buffer_ptr(&active_state->compression_buffer),
buffer_len(&active_state->compression_buffer));
DBG(debug("compression: raw %d compressed %d", len,
buffer_len(&active_state->outgoing_packet)));
}
/* sizeof (packet_len + pad_len + payload) */
len = buffer_len(&active_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 (active_state->extra_pad) {
/* will wrap if extra_pad+padlen > 255 */
active_state->extra_pad =
roundup(active_state->extra_pad, block_size);
pad = active_state->extra_pad -
((len + padlen) % active_state->extra_pad);
DBG(debug3("%s: adding %d (len %d padlen %d extra_pad %d)",
__func__, pad, len, padlen, active_state->extra_pad));
padlen += pad;
active_state->extra_pad = 0;
}
cp = buffer_append_space(&active_state->outgoing_packet, padlen);
if (enc && !active_state->send_context.plaintext) {
/* random padding */
for (i = 0; i < padlen; i++) {
if (i % 4 == 0)
rnd = arc4random();
cp[i] = rnd & 0xff;
rnd >>= 8;
}
} else {
/* clear padding */
explicit_bzero(cp, padlen);
}
/* sizeof (packet_len + pad_len + payload + padding) */
len = buffer_len(&active_state->outgoing_packet);
cp = buffer_ptr(&active_state->outgoing_packet);
/* packet_length includes payload, padding and padding length field */
put_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) {
macbuf = mac_compute(mac, active_state->p_send.seqnr,
buffer_ptr(&active_state->outgoing_packet), len);
DBG(debug("done calc MAC out #%d", active_state->p_send.seqnr));
}
/* encrypt packet and append to output buffer. */
cp = buffer_append_space(&active_state->output, len + authlen);
if (cipher_crypt(&active_state->send_context, active_state->p_send.seqnr,
cp, buffer_ptr(&active_state->outgoing_packet),
len - aadlen, aadlen, authlen) != 0)
fatal("%s: cipher_crypt failed", __func__);
/* append unencrypted MAC */
if (mac && mac->enabled) {
if (mac->etm) {
/* EtM: compute mac over aadlen + cipher text */
macbuf = mac_compute(mac,
active_state->p_send.seqnr, cp, len);
DBG(debug("done calc MAC(EtM) out #%d",
active_state->p_send.seqnr));
}
buffer_append(&active_state->output, macbuf, mac->mac_len);
}
#ifdef PACKET_DEBUG
fprintf(stderr, "encrypted: ");
buffer_dump(&active_state->output);
#endif
/* increment sequence number for outgoing packets */
if (++active_state->p_send.seqnr == 0)
logit("outgoing seqnr wraps around");
if (++active_state->p_send.packets == 0)
if (!(datafellows & SSH_BUG_NOREKEY))
fatal("XXX too many packets with same key");
active_state->p_send.blocks += len / block_size;
active_state->p_send.bytes += len;
buffer_clear(&active_state->outgoing_packet);
if (type == SSH2_MSG_NEWKEYS)
set_newkeys(MODE_OUT);
else if (type == SSH2_MSG_USERAUTH_SUCCESS && active_state->server_side)
packet_enable_delayed_compress();
}
static void
packet_send2(void)
{
struct packet *p;
u_char type, *cp;
cp = buffer_ptr(&active_state->outgoing_packet);
type = cp[5];
/* during rekeying we can only send key exchange messages */
if (active_state->rekeying) {
if ((type < SSH2_MSG_TRANSPORT_MIN) ||
(type > SSH2_MSG_TRANSPORT_MAX) ||
(type == SSH2_MSG_SERVICE_REQUEST) ||
(type == SSH2_MSG_SERVICE_ACCEPT)) {
debug("enqueue packet: %u", type);
p = xcalloc(1, sizeof(*p));
p->type = type;
memcpy(&p->payload, &active_state->outgoing_packet,
sizeof(Buffer));
buffer_init(&active_state->outgoing_packet);
TAILQ_INSERT_TAIL(&active_state->outgoing, p, next);
return;
}
}
/* rekeying starts with sending KEXINIT */
if (type == SSH2_MSG_KEXINIT)
active_state->rekeying = 1;
packet_send2_wrapped();
/* after a NEWKEYS message we can send the complete queue */
if (type == SSH2_MSG_NEWKEYS) {
active_state->rekeying = 0;
active_state->rekey_time = monotime();
while ((p = TAILQ_FIRST(&active_state->outgoing))) {
type = p->type;
debug("dequeue packet: %u", type);
buffer_free(&active_state->outgoing_packet);
memcpy(&active_state->outgoing_packet, &p->payload,
sizeof(Buffer));
TAILQ_REMOVE(&active_state->outgoing, p, next);
free(p);
packet_send2_wrapped();
}
}
}
void
packet_send(void)
{
if (compat20)
packet_send2();
else
packet_send1();
DBG(debug("packet_send done"));
}
/*
* 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
packet_read_seqnr(u_int32_t *seqnr_p)
{
int type, len, ret, cont, ms_remain = 0;
fd_set *setp;
char buf[8192];
struct timeval timeout, start, *timeoutp = NULL;
DBG(debug("packet_read()"));
setp = (fd_set *)xcalloc(howmany(active_state->connection_in + 1,
NFDBITS), sizeof(fd_mask));
/* Since we are blocking, ensure that all written packets have been sent. */
packet_write_wait();
/* Stay in the loop until we have received a complete packet. */
for (;;) {
/* Try to read a packet from the buffer. */
type = packet_read_poll_seqnr(seqnr_p);
if (!compat20 && (
type == SSH_SMSG_SUCCESS
|| type == SSH_SMSG_FAILURE
|| type == SSH_CMSG_EOF
|| type == SSH_CMSG_EXIT_CONFIRMATION))
packet_check_eom();
/* If we got a packet, return it. */
if (type != SSH_MSG_NONE) {
free(setp);
return type;
}
/*
* Otherwise, wait for some data to arrive, add it to the
* buffer, and try again.
*/
memset(setp, 0, howmany(active_state->connection_in + 1,
NFDBITS) * sizeof(fd_mask));
FD_SET(active_state->connection_in, setp);
if (active_state->packet_timeout_ms > 0) {
ms_remain = active_state->packet_timeout_ms;
timeoutp = &timeout;
}
/* Wait for some data to arrive. */
for (;;) {
if (active_state->packet_timeout_ms != -1) {
ms_to_timeval(&timeout, ms_remain);
gettimeofday(&start, NULL);
}
if ((ret = select(active_state->connection_in + 1, setp,
NULL, NULL, timeoutp)) >= 0)
break;
if (errno != EAGAIN && errno != EINTR &&
errno != EWOULDBLOCK)
break;
if (active_state->packet_timeout_ms == -1)
continue;
ms_subtract_diff(&start, &ms_remain);
if (ms_remain <= 0) {
ret = 0;
break;
}
}
if (ret == 0) {
logit("Connection to %.200s timed out while "
"waiting to read", get_remote_ipaddr());
cleanup_exit(255);
}
/* Read data from the socket. */
do {
cont = 0;
len = roaming_read(active_state->connection_in, buf,
sizeof(buf), &cont);
} while (len == 0 && cont);
if (len == 0) {
logit("Connection closed by %.200s", get_remote_ipaddr());
cleanup_exit(255);
}
if (len < 0)
fatal("Read from socket failed: %.100s", strerror(errno));
/* Append it to the buffer. */
packet_process_incoming(buf, len);
}
/* NOTREACHED */
}
int
packet_read(void)
{
return packet_read_seqnr(NULL);
}
/*
* Waits until a packet has been received, verifies that its type matches
* that given, and gives a fatal error and exits if there is a mismatch.
*/
void
packet_read_expect(int expected_type)
{
int type;
type = packet_read();
if (type != expected_type)
packet_disconnect("Protocol error: expected packet type %d, got %d",
expected_type, type);
}
/* Checks if a full packet is available in the data received so far via
* packet_process_incoming. If so, reads the packet; otherwise returns
* SSH_MSG_NONE. This does not wait for data from the connection.
*
* SSH_MSG_DISCONNECT is handled specially here. Also,
* SSH_MSG_IGNORE messages are skipped by this function and are never returned
* to higher levels.
*/
static int
packet_read_poll1(void)
{
u_int len, padded_len;
u_char *cp, type;
u_int checksum, stored_checksum;
/* Check if input size is less than minimum packet size. */
if (buffer_len(&active_state->input) < 4 + 8)
return SSH_MSG_NONE;
/* Get length of incoming packet. */
cp = buffer_ptr(&active_state->input);
len = get_u32(cp);
if (len < 1 + 2 + 2 || len > 256 * 1024)
packet_disconnect("Bad packet length %u.", len);
padded_len = (len + 8) & ~7;
/* Check if the packet has been entirely received. */
if (buffer_len(&active_state->input) < 4 + padded_len)
return SSH_MSG_NONE;
/* The entire packet is in buffer. */
/* Consume packet length. */
buffer_consume(&active_state->input, 4);
/*
* Cryptographic attack detector for ssh
* (C)1998 CORE-SDI, Buenos Aires Argentina
* Ariel Futoransky(futo@core-sdi.com)
*/
if (!active_state->receive_context.plaintext) {
switch (detect_attack(buffer_ptr(&active_state->input),
padded_len)) {
case DEATTACK_DETECTED:
packet_disconnect("crc32 compensation attack: "
"network attack detected");
case DEATTACK_DOS_DETECTED:
packet_disconnect("deattack denial of "
"service detected");
}
}
/* Decrypt data to incoming_packet. */
buffer_clear(&active_state->incoming_packet);
cp = buffer_append_space(&active_state->incoming_packet, padded_len);
if (cipher_crypt(&active_state->receive_context, 0, cp,
buffer_ptr(&active_state->input), padded_len, 0, 0) != 0)
fatal("%s: cipher_crypt failed", __func__);
buffer_consume(&active_state->input, padded_len);
#ifdef PACKET_DEBUG
fprintf(stderr, "read_poll plain: ");
buffer_dump(&active_state->incoming_packet);
#endif
/* Compute packet checksum. */
checksum = ssh_crc32(buffer_ptr(&active_state->incoming_packet),
buffer_len(&active_state->incoming_packet) - 4);
/* Skip padding. */
buffer_consume(&active_state->incoming_packet, 8 - len % 8);
/* Test check bytes. */
if (len != buffer_len(&active_state->incoming_packet))
packet_disconnect("packet_read_poll1: len %d != buffer_len %d.",
len, buffer_len(&active_state->incoming_packet));
cp = (u_char *)buffer_ptr(&active_state->incoming_packet) + len - 4;
stored_checksum = get_u32(cp);
if (checksum != stored_checksum)
packet_disconnect("Corrupted check bytes on input.");
buffer_consume_end(&active_state->incoming_packet, 4);
if (active_state->packet_compression) {
buffer_clear(&active_state->compression_buffer);
buffer_uncompress(&active_state->incoming_packet,
&active_state->compression_buffer);
buffer_clear(&active_state->incoming_packet);
buffer_append(&active_state->incoming_packet,
buffer_ptr(&active_state->compression_buffer),
buffer_len(&active_state->compression_buffer));
}
active_state->p_read.packets++;
active_state->p_read.bytes += padded_len + 4;
type = buffer_get_char(&active_state->incoming_packet);
if (type < SSH_MSG_MIN || type > SSH_MSG_MAX)
packet_disconnect("Invalid ssh1 packet type: %d", type);
return type;
}
static int
packet_read_poll2(u_int32_t *seqnr_p)
{
u_int padlen, need;
u_char *macbuf = NULL, *cp, type;
u_int maclen, authlen = 0, aadlen = 0, block_size;
Enc *enc = NULL;
Mac *mac = NULL;
Comp *comp = NULL;
if (active_state->packet_discard)
return SSH_MSG_NONE;
if (active_state->newkeys[MODE_IN] != NULL) {
enc = &active_state->newkeys[MODE_IN]->enc;
mac = &active_state->newkeys[MODE_IN]->mac;
comp = &active_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 && active_state->packlen == 0) {
if (cipher_get_length(&active_state->receive_context,
&active_state->packlen,
active_state->p_read.seqnr,
buffer_ptr(&active_state->input),
buffer_len(&active_state->input)) != 0)
return SSH_MSG_NONE;
if (active_state->packlen < 1 + 4 ||
active_state->packlen > PACKET_MAX_SIZE) {
#ifdef PACKET_DEBUG
buffer_dump(&active_state->input);
#endif
logit("Bad packet length %u.", active_state->packlen);
packet_disconnect("Packet corrupt");
}
buffer_clear(&active_state->incoming_packet);
} else if (active_state->packlen == 0) {
/*
* check if input size is less than the cipher block size,
* decrypt first block and extract length of incoming packet
*/
if (buffer_len(&active_state->input) < block_size)
return SSH_MSG_NONE;
buffer_clear(&active_state->incoming_packet);
cp = buffer_append_space(&active_state->incoming_packet,
block_size);
if (cipher_crypt(&active_state->receive_context,
active_state->p_read.seqnr, cp,
buffer_ptr(&active_state->input), block_size, 0, 0) != 0)
fatal("Decryption integrity check failed");
cp = buffer_ptr(&active_state->incoming_packet);
active_state->packlen = get_u32(cp);
if (active_state->packlen < 1 + 4 ||
active_state->packlen > PACKET_MAX_SIZE) {
#ifdef PACKET_DEBUG
buffer_dump(&active_state->incoming_packet);
#endif
logit("Bad packet length %u.", active_state->packlen);
packet_start_discard(enc, mac, active_state->packlen,
PACKET_MAX_SIZE);
return SSH_MSG_NONE;
}
buffer_consume(&active_state->input, block_size);
}
DBG(debug("input: packet len %u", active_state->packlen+4));
if (aadlen) {
/* only the payload is encrypted */
need = active_state->packlen;
} else {
/*
* the payload size and the payload are encrypted, but we
* have a partial packet of block_size bytes
*/
need = 4 + active_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);
packet_start_discard(enc, mac, active_state->packlen,
PACKET_MAX_SIZE - block_size);
return SSH_MSG_NONE;
}
/*
* 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 (buffer_len(&active_state->input) < aadlen + need + authlen + maclen)
return SSH_MSG_NONE;
#ifdef PACKET_DEBUG
fprintf(stderr, "read_poll enc/full: ");
buffer_dump(&active_state->input);
#endif
/* EtM: compute mac over encrypted input */
if (mac && mac->enabled && mac->etm)
macbuf = mac_compute(mac, active_state->p_read.seqnr,
buffer_ptr(&active_state->input), aadlen + need);
cp = buffer_append_space(&active_state->incoming_packet, aadlen + need);
if (cipher_crypt(&active_state->receive_context,
active_state->p_read.seqnr, cp,
buffer_ptr(&active_state->input), need, aadlen, authlen) != 0)
fatal("Decryption integrity check failed");
buffer_consume(&active_state->input, aadlen + need + authlen);
/*
* compute MAC over seqnr and packet,
* increment sequence number for incoming packet
*/
if (mac && mac->enabled) {
if (!mac->etm)
macbuf = mac_compute(mac, active_state->p_read.seqnr,
buffer_ptr(&active_state->incoming_packet),
buffer_len(&active_state->incoming_packet));
if (timingsafe_bcmp(macbuf, buffer_ptr(&active_state->input),
mac->mac_len) != 0) {
logit("Corrupted MAC on input.");
if (need > PACKET_MAX_SIZE)
fatal("internal error need %d", need);
packet_start_discard(enc, mac, active_state->packlen,
PACKET_MAX_SIZE - need);
return SSH_MSG_NONE;
}
DBG(debug("MAC #%d ok", active_state->p_read.seqnr));
buffer_consume(&active_state->input, mac->mac_len);
}
/* XXX now it's safe to use fatal/packet_disconnect */
if (seqnr_p != NULL)
*seqnr_p = active_state->p_read.seqnr;
if (++active_state->p_read.seqnr == 0)
logit("incoming seqnr wraps around");
if (++active_state->p_read.packets == 0)
if (!(datafellows & SSH_BUG_NOREKEY))
fatal("XXX too many packets with same key");
active_state->p_read.blocks += (active_state->packlen + 4) / block_size;
active_state->p_read.bytes += active_state->packlen + 4;
/* get padlen */
cp = buffer_ptr(&active_state->incoming_packet);
padlen = cp[4];
DBG(debug("input: padlen %d", padlen));
if (padlen < 4)
packet_disconnect("Corrupted padlen %d on input.", padlen);
/* skip packet size + padlen, discard padding */
buffer_consume(&active_state->incoming_packet, 4 + 1);
buffer_consume_end(&active_state->incoming_packet, padlen);
DBG(debug("input: len before de-compress %d",
buffer_len(&active_state->incoming_packet)));
if (comp && comp->enabled) {
buffer_clear(&active_state->compression_buffer);
buffer_uncompress(&active_state->incoming_packet,
&active_state->compression_buffer);
buffer_clear(&active_state->incoming_packet);
buffer_append(&active_state->incoming_packet,
buffer_ptr(&active_state->compression_buffer),
buffer_len(&active_state->compression_buffer));
DBG(debug("input: len after de-compress %d",
buffer_len(&active_state->incoming_packet)));
}
/*
* get packet type, implies consume.
* return length of payload (without type field)
*/
type = buffer_get_char(&active_state->incoming_packet);
if (type < SSH2_MSG_MIN || type >= SSH2_MSG_LOCAL_MIN)
packet_disconnect("Invalid ssh2 packet type: %d", type);
if (type == SSH2_MSG_NEWKEYS)
set_newkeys(MODE_IN);
else if (type == SSH2_MSG_USERAUTH_SUCCESS &&
!active_state->server_side)
packet_enable_delayed_compress();
#ifdef PACKET_DEBUG
fprintf(stderr, "read/plain[%d]:\r\n", type);
buffer_dump(&active_state->incoming_packet);
#endif
/* reset for next packet */
active_state->packlen = 0;
return type;
}
int
packet_read_poll_seqnr(u_int32_t *seqnr_p)
{
u_int reason, seqnr;
u_char type;
char *msg;
for (;;) {
if (compat20) {
type = packet_read_poll2(seqnr_p);
if (type) {
active_state->keep_alive_timeouts = 0;
DBG(debug("received packet type %d", type));
}
switch (type) {
case SSH2_MSG_IGNORE:
debug3("Received SSH2_MSG_IGNORE");
break;
case SSH2_MSG_DEBUG:
packet_get_char();
msg = packet_get_string(NULL);
debug("Remote: %.900s", msg);
free(msg);
msg = packet_get_string(NULL);
free(msg);
break;
case SSH2_MSG_DISCONNECT:
reason = packet_get_int();
msg = packet_get_string(NULL);
/* Ignore normal client exit notifications */
do_log2(active_state->server_side &&
reason == SSH2_DISCONNECT_BY_APPLICATION ?
SYSLOG_LEVEL_INFO : SYSLOG_LEVEL_ERROR,
"Received disconnect from %s: %u: %.400s",
get_remote_ipaddr(), reason, msg);
free(msg);
cleanup_exit(255);
break;
case SSH2_MSG_UNIMPLEMENTED:
seqnr = packet_get_int();
debug("Received SSH2_MSG_UNIMPLEMENTED for %u",
seqnr);
break;
default:
return type;
}
} else {
type = packet_read_poll1();
switch (type) {
case SSH_MSG_NONE:
return SSH_MSG_NONE;
case SSH_MSG_IGNORE:
break;
case SSH_MSG_DEBUG:
msg = packet_get_string(NULL);
debug("Remote: %.900s", msg);
free(msg);
break;
case SSH_MSG_DISCONNECT:
msg = packet_get_string(NULL);
error("Received disconnect from %s: %.400s",
get_remote_ipaddr(), msg);
cleanup_exit(255);
break;
default:
DBG(debug("received packet type %d", type));
return type;
}
}
}
}
/*
* Buffers the given amount of input characters. This is intended to be used
* together with packet_read_poll.
*/
void
packet_process_incoming(const char *buf, u_int len)
{
if (active_state->packet_discard) {
active_state->keep_alive_timeouts = 0; /* ?? */
if (len >= active_state->packet_discard)
packet_stop_discard();
active_state->packet_discard -= len;
return;
}
buffer_append(&active_state->input, buf, len);
}
/* Returns a character from the packet. */
u_int
packet_get_char(void)
{
char ch;
buffer_get(&active_state->incoming_packet, &ch, 1);
return (u_char) ch;
}
/* Returns an integer from the packet data. */
u_int
packet_get_int(void)
{
return buffer_get_int(&active_state->incoming_packet);
}
/* Returns an 64 bit integer from the packet data. */
u_int64_t
packet_get_int64(void)
{
return buffer_get_int64(&active_state->incoming_packet);
}
/*
* Returns an arbitrary precision integer from the packet data. The integer
* must have been initialized before this call.
*/
#ifdef WITH_OPENSSL
void
packet_get_bignum(BIGNUM * value)
{
buffer_get_bignum(&active_state->incoming_packet, value);
}
void
packet_get_bignum2(BIGNUM * value)
{
buffer_get_bignum2(&active_state->incoming_packet, value);
}
#ifdef OPENSSL_HAS_ECC
void
packet_get_ecpoint(const EC_GROUP *curve, EC_POINT *point)
{
buffer_get_ecpoint(&active_state->incoming_packet, curve, point);
}
#endif
void *
packet_get_raw(u_int *length_ptr)
{
u_int bytes = buffer_len(&active_state->incoming_packet);
if (length_ptr != NULL)
*length_ptr = bytes;
return buffer_ptr(&active_state->incoming_packet);
}
#endif
int
packet_remaining(void)
{
return buffer_len(&active_state->incoming_packet);
}
/*
* Returns a string from the packet data. The string is allocated using
* xmalloc; it is the responsibility of the calling program to free it when
* no longer needed. The length_ptr argument may be NULL, or point to an
* integer into which the length of the string is stored.
*/
void *
packet_get_string(u_int *length_ptr)
{
return buffer_get_string(&active_state->incoming_packet, length_ptr);
}
const void *
packet_get_string_ptr(u_int *length_ptr)
{
return buffer_get_string_ptr(&active_state->incoming_packet, length_ptr);
}
/* Ensures the returned string has no embedded \0 characters in it. */
char *
packet_get_cstring(u_int *length_ptr)
{
return buffer_get_cstring(&active_state->incoming_packet, length_ptr);
}
/*
* 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 packet_write_wait.
*/
void
packet_send_debug(const char *fmt,...)
{
char buf[1024];
va_list args;
if (compat20 && (datafellows & SSH_BUG_DEBUG))
return;
va_start(args, fmt);
vsnprintf(buf, sizeof(buf), fmt, args);
va_end(args);
if (compat20) {
packet_start(SSH2_MSG_DEBUG);
packet_put_char(0); /* bool: always display */
packet_put_cstring(buf);
packet_put_cstring("");
} else {
packet_start(SSH_MSG_DEBUG);
packet_put_cstring(buf);
}
packet_send();
packet_write_wait();
}
/*
* 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
packet_disconnect(const char *fmt,...)
{
char buf[1024];
va_list args;
static int disconnecting = 0;
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.
*/
va_start(args, fmt);
vsnprintf(buf, sizeof(buf), fmt, args);
va_end(args);
/* Display the error locally */
logit("Disconnecting: %.100s", buf);
/* Send the disconnect message to the other side, and wait for it to get sent. */
if (compat20) {
packet_start(SSH2_MSG_DISCONNECT);
packet_put_int(SSH2_DISCONNECT_PROTOCOL_ERROR);
packet_put_cstring(buf);
packet_put_cstring("");
} else {
packet_start(SSH_MSG_DISCONNECT);
packet_put_cstring(buf);
}
packet_send();
packet_write_wait();
/* Stop listening for connections. */
channel_close_all();
/* Close the connection. */
packet_close();
cleanup_exit(255);
}
/* Checks if there is any buffered output, and tries to write some of the output. */
void
packet_write_poll(void)
{
int len = buffer_len(&active_state->output);
int cont;
if (len > 0) {
cont = 0;
len = roaming_write(active_state->connection_out,
buffer_ptr(&active_state->output), len, &cont);
if (len == -1) {
if (errno == EINTR || errno == EAGAIN ||
errno == EWOULDBLOCK)
return;
fatal("Write failed: %.100s", strerror(errno));
}
if (len == 0 && !cont)
fatal("Write connection closed");
buffer_consume(&active_state->output, len);
}
}
/*
* Calls packet_write_poll repeatedly until all pending output data has been
* written.
*/
void
packet_write_wait(void)
{
fd_set *setp;
int ret, ms_remain = 0;
struct timeval start, timeout, *timeoutp = NULL;
setp = (fd_set *)xcalloc(howmany(active_state->connection_out + 1,
NFDBITS), sizeof(fd_mask));
packet_write_poll();
while (packet_have_data_to_write()) {
memset(setp, 0, howmany(active_state->connection_out + 1,
NFDBITS) * sizeof(fd_mask));
FD_SET(active_state->connection_out, setp);
if (active_state->packet_timeout_ms > 0) {
ms_remain = active_state->packet_timeout_ms;
timeoutp = &timeout;
}
for (;;) {
if (active_state->packet_timeout_ms != -1) {
ms_to_timeval(&timeout, ms_remain);
gettimeofday(&start, NULL);
}
if ((ret = select(active_state->connection_out + 1,
NULL, setp, NULL, timeoutp)) >= 0)
break;
if (errno != EAGAIN && errno != EINTR &&
errno != EWOULDBLOCK)
break;
if (active_state->packet_timeout_ms == -1)
continue;
ms_subtract_diff(&start, &ms_remain);
if (ms_remain <= 0) {
ret = 0;
break;
}
}
if (ret == 0) {
logit("Connection to %.200s timed out while "
"waiting to write", get_remote_ipaddr());
cleanup_exit(255);
}
packet_write_poll();
}
free(setp);
}
/* Returns true if there is buffered data to write to the connection. */
int
packet_have_data_to_write(void)
{
return buffer_len(&active_state->output) != 0;
}
/* Returns true if there is not too much data to write to the connection. */
int
packet_not_very_much_data_to_write(void)
{
if (active_state->interactive_mode)
return buffer_len(&active_state->output) < 16384;
else
return buffer_len(&active_state->output) < 128 * 1024;
}
static void
packet_set_tos(int tos)
{
#ifndef IP_TOS_IS_BROKEN
if (!packet_connection_is_on_socket())
return;
switch (packet_connection_af()) {
# ifdef IP_TOS
case AF_INET:
debug3("%s: set IP_TOS 0x%02x", __func__, tos);
if (setsockopt(active_state->connection_in,
IPPROTO_IP, IP_TOS, &tos, sizeof(tos)) < 0)
error("setsockopt IP_TOS %d: %.100s:",
tos, strerror(errno));
break;
# endif /* IP_TOS */
# ifdef IPV6_TCLASS
case AF_INET6:
debug3("%s: set IPV6_TCLASS 0x%02x", __func__, tos);
if (setsockopt(active_state->connection_in,
IPPROTO_IPV6, IPV6_TCLASS, &tos, sizeof(tos)) < 0)
error("setsockopt IPV6_TCLASS %d: %.100s:",
tos, strerror(errno));
break;
# endif /* IPV6_TCLASS */
}
#endif /* IP_TOS_IS_BROKEN */
}
/* Informs that the current session is interactive. Sets IP flags for that. */
void
packet_set_interactive(int interactive, int qos_interactive, int qos_bulk)
{
if (active_state->set_interactive_called)
return;
active_state->set_interactive_called = 1;
/* Record that we are in interactive mode. */
active_state->interactive_mode = interactive;
/* Only set socket options if using a socket. */
if (!packet_connection_is_on_socket())
return;
set_nodelay(active_state->connection_in);
packet_set_tos(interactive ? qos_interactive : qos_bulk);
}
/* Returns true if the current connection is interactive. */
int
packet_is_interactive(void)
{
return active_state->interactive_mode;
}
int
packet_set_maxsize(u_int s)
{
if (active_state->set_maxsize_called) {
logit("packet_set_maxsize: called twice: old %d new %d",
active_state->max_packet_size, s);
return -1;
}
if (s < 4 * 1024 || s > 1024 * 1024) {
logit("packet_set_maxsize: bad size %d", s);
return -1;
}
active_state->set_maxsize_called = 1;
debug("packet_set_maxsize: setting to %d", s);
active_state->max_packet_size = s;
return s;
}
int
packet_inc_alive_timeouts(void)
{
return ++active_state->keep_alive_timeouts;
}
void
packet_set_alive_timeouts(int ka)
{
active_state->keep_alive_timeouts = ka;
}
u_int
packet_get_maxsize(void)
{
return active_state->max_packet_size;
}
/* roundup current message to pad bytes */
void
packet_add_padding(u_char pad)
{
active_state->extra_pad = pad;
}
/*
* 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.
*/
void
packet_send_ignore(int nbytes)
{
u_int32_t rnd = 0;
int i;
packet_start(compat20 ? SSH2_MSG_IGNORE : SSH_MSG_IGNORE);
packet_put_int(nbytes);
for (i = 0; i < nbytes; i++) {
if (i % 4 == 0)
rnd = arc4random();
packet_put_char((u_char)rnd & 0xff);
rnd >>= 8;
}
}
#define MAX_PACKETS (1U<<31)
int
packet_need_rekeying(void)
{
if (datafellows & SSH_BUG_NOREKEY)
return 0;
return
(active_state->p_send.packets > MAX_PACKETS) ||
(active_state->p_read.packets > MAX_PACKETS) ||
(active_state->max_blocks_out &&
(active_state->p_send.blocks > active_state->max_blocks_out)) ||
(active_state->max_blocks_in &&
(active_state->p_read.blocks > active_state->max_blocks_in)) ||
(active_state->rekey_interval != 0 && active_state->rekey_time +
active_state->rekey_interval <= monotime());
}
void
packet_set_rekey_limits(u_int32_t bytes, time_t seconds)
{
debug3("rekey after %lld bytes, %d seconds", (long long)bytes,
(int)seconds);
active_state->rekey_limit = bytes;
active_state->rekey_interval = seconds;
/*
* We set the time here so that in post-auth privsep slave we count
* from the completion of the authentication.
*/
active_state->rekey_time = monotime();
}
time_t
packet_get_rekey_timeout(void)
{
time_t seconds;
seconds = active_state->rekey_time + active_state->rekey_interval -
monotime();
return (seconds <= 0 ? 1 : seconds);
}
void
packet_set_server(void)
{
active_state->server_side = 1;
}
void
packet_set_authenticated(void)
{
active_state->after_authentication = 1;
}
void *
packet_get_input(void)
{
return (void *)&active_state->input;
}
void *
packet_get_output(void)
{
return (void *)&active_state->output;
}
void *
packet_get_newkeys(int mode)
{
return (void *)active_state->newkeys[mode];
}
/*
* Save the state for the real connection, and use a separate state when
* resuming a suspended connection.
*/
void
packet_backup_state(void)
{
struct session_state *tmp;
close(active_state->connection_in);
active_state->connection_in = -1;
close(active_state->connection_out);
active_state->connection_out = -1;
if (backup_state)
tmp = backup_state;
else
tmp = alloc_session_state();
backup_state = active_state;
active_state = tmp;
}
/*
* Swap in the old state when resuming a connecion.
*/
void
packet_restore_state(void)
{
struct session_state *tmp;
void *buf;
u_int len;
tmp = backup_state;
backup_state = active_state;
active_state = tmp;
active_state->connection_in = backup_state->connection_in;
backup_state->connection_in = -1;
active_state->connection_out = backup_state->connection_out;
backup_state->connection_out = -1;
len = buffer_len(&backup_state->input);
if (len > 0) {
buf = buffer_ptr(&backup_state->input);
buffer_append(&active_state->input, buf, len);
buffer_clear(&backup_state->input);
add_recv_bytes(len);
}
}
/* Reset after_authentication and reset compression in post-auth privsep */
void
packet_set_postauth(void)
{
Comp *comp;
int mode;
debug("%s: called", __func__);
/* This was set in net child, but is not visible in user child */
active_state->after_authentication = 1;
active_state->rekeying = 0;
for (mode = 0; mode < MODE_MAX; mode++) {
if (active_state->newkeys[mode] == NULL)
continue;
comp = &active_state->newkeys[mode]->comp;
if (comp && comp->enabled)
packet_init_compression();
}
}
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