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/*
* Copyright (C) 2000, 2001, 2002, 2003, 2004, 2005, 2008, 2009 Free Software Foundation, Inc.
*
* Author: Nikos Mavrogiannopoulos
*
* This file is part of GNUTLS.
*
* The GNUTLS library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public License
* as published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
* USA
*
*/
/* Some high level functions to be used in the record encryption are
* included here.
*/
#include "gnutls_int.h"
#include "gnutls_errors.h"
#include "gnutls_compress.h"
#include "gnutls_cipher.h"
#include "gnutls_algorithms.h"
#include "gnutls_hash_int.h"
#include "gnutls_cipher_int.h"
#include "debug.h"
#include "gnutls_num.h"
#include "gnutls_datum.h"
#include "gnutls_kx.h"
#include "gnutls_record.h"
#include "gnutls_constate.h"
#include <random.h>
inline static int
is_write_comp_null (gnutls_session_t session)
{
if (session->security_parameters.write_compression_algorithm ==
GNUTLS_COMP_NULL)
return 0;
return 1;
}
inline static int
is_read_comp_null (gnutls_session_t session)
{
if (session->security_parameters.read_compression_algorithm ==
GNUTLS_COMP_NULL)
return 0;
return 1;
}
/* returns ciphertext which contains the headers too. This also
* calculates the size in the header field.
*
* If random pad != 0 then the random pad data will be appended.
*/
int
_gnutls_encrypt (gnutls_session_t session, const opaque * headers,
size_t headers_size, const opaque * data,
size_t data_size, opaque * ciphertext,
size_t ciphertext_size, content_type_t type, int random_pad)
{
gnutls_datum_t plain;
gnutls_datum_t comp;
int ret;
int free_comp = 1;
plain.data = (opaque *) data;
plain.size = data_size;
if (plain.size == 0 || is_write_comp_null (session) == 0)
{
comp = plain;
free_comp = 0;
}
else
{
/* Here comp is allocated and must be
* freed.
*/
ret = _gnutls_m_plaintext2compressed (session, &comp, &plain);
if (ret < 0)
{
gnutls_assert ();
return ret;
}
}
ret = _gnutls_compressed2ciphertext (session, &ciphertext[headers_size],
ciphertext_size - headers_size,
comp, type, random_pad);
if (free_comp)
_gnutls_free_datum (&comp);
if (ret < 0)
{
gnutls_assert ();
return ret;
}
/* copy the headers */
memcpy (ciphertext, headers, headers_size);
_gnutls_write_uint16 (ret, &ciphertext[3]);
return ret + headers_size;
}
/* Decrypts the given data.
* Returns the decrypted data length.
*/
int
_gnutls_decrypt (gnutls_session_t session, opaque * ciphertext,
size_t ciphertext_size, uint8_t * data,
size_t max_data_size, content_type_t type)
{
gnutls_datum_t gtxt;
gnutls_datum_t gcipher;
int ret;
if (ciphertext_size == 0)
return 0;
gcipher.size = ciphertext_size;
gcipher.data = ciphertext;
ret =
_gnutls_ciphertext2compressed (session, data, max_data_size,
gcipher, type);
if (ret < 0)
{
return ret;
}
if (ret == 0 || is_read_comp_null (session) == 0)
{
/* ret == ret */
}
else
{
gnutls_datum_t gcomp;
/* compression has this malloc overhead.
*/
gcomp.data = data;
gcomp.size = ret;
ret = _gnutls_m_compressed2plaintext (session, >xt, &gcomp);
if (ret < 0)
{
return ret;
}
if (gtxt.size > MAX_RECORD_RECV_SIZE)
{
gnutls_assert ();
_gnutls_free_datum (>xt);
/* This shouldn't have happen and
* is a TLS fatal error.
*/
return GNUTLS_E_DECOMPRESSION_FAILED;
}
/* This check is not really needed */
if (max_data_size < MAX_RECORD_RECV_SIZE)
{
gnutls_assert ();
_gnutls_free_datum (>xt);
return GNUTLS_E_INTERNAL_ERROR;
}
memcpy (data, gtxt.data, gtxt.size);
ret = gtxt.size;
_gnutls_free_datum (>xt);
}
return ret;
}
static inline int
mac_init (digest_hd_st * td, gnutls_mac_algorithm_t mac, opaque * secret,
int secret_size, int ver)
{
int ret = 0;
if (mac == GNUTLS_MAC_NULL)
{
return GNUTLS_E_HASH_FAILED;
}
if (ver == GNUTLS_SSL3)
{ /* SSL 3.0 */
ret = _gnutls_mac_init_ssl3 (td, mac, secret, secret_size);
}
else
{ /* TLS 1.x */
ret = _gnutls_hmac_init (td, mac, secret, secret_size);
}
return ret;
}
static inline void
mac_hash (digest_hd_st * td, void * data, int data_size, int ver)
{
if (ver == GNUTLS_SSL3)
{ /* SSL 3.0 */
_gnutls_hash (td, data, data_size);
}
else
{
_gnutls_hmac (td, data, data_size);
}
}
static inline void
mac_deinit (digest_hd_st * td, opaque * res, int ver)
{
if (ver == GNUTLS_SSL3)
{ /* SSL 3.0 */
_gnutls_mac_deinit_ssl3 (td, res);
}
else
{
_gnutls_hmac_deinit (td, res);
}
}
inline static int
calc_enc_length (gnutls_session_t session, int data_size,
int hash_size, uint8_t * pad, int random_pad,
cipher_type_t block_algo, uint16_t blocksize)
{
uint8_t rnd;
int length, ret;
*pad = 0;
switch (block_algo)
{
case CIPHER_STREAM:
length = data_size + hash_size;
break;
case CIPHER_BLOCK:
ret = _gnutls_rnd (GNUTLS_RND_NONCE, &rnd, 1);
if (ret < 0)
{
gnutls_assert ();
return ret;
}
/* make rnd a multiple of blocksize */
if (session->security_parameters.version == GNUTLS_SSL3 ||
random_pad == 0)
{
rnd = 0;
}
else
{
rnd = (rnd / blocksize) * blocksize;
/* added to avoid the case of pad calculated 0
* seen below for pad calculation.
*/
if (rnd > blocksize)
rnd -= blocksize;
}
length = data_size + hash_size;
*pad = (uint8_t) (blocksize - (length % blocksize)) + rnd;
length += *pad;
if (_gnutls_version_has_explicit_iv
(session->security_parameters.version))
length += blocksize; /* for the IV */
break;
default:
gnutls_assert ();
return GNUTLS_E_INTERNAL_ERROR;
}
return length;
}
#define PREAMBLE_SIZE 16
static inline int make_preamble(opaque* uint64_data, opaque type, uint16_t c_length, opaque ver, opaque* preamble)
{
opaque minor = _gnutls_version_get_minor (ver);
opaque major = _gnutls_version_get_major (ver);
opaque *p = preamble;
memcpy(p, uint64_data, 8);
p+=8;
*p=type; p++;
if (_gnutls_version_has_variable_padding (ver))
{ /* TLS 1.0 or higher */
*p = major; p++;
*p = minor; p++;
}
memcpy(p, &c_length, 2);
p+=2;
return p-preamble;
}
/* This is the actual encryption
* Encrypts the given compressed datum, and puts the result to cipher_data,
* which has cipher_size size.
* return the actual encrypted data length.
*/
int
_gnutls_compressed2ciphertext (gnutls_session_t session,
opaque * cipher_data, int cipher_size,
gnutls_datum_t compressed,
content_type_t _type, int random_pad)
{
uint8_t MAC[MAX_HASH_SIZE];
uint16_t c_length;
uint8_t pad;
int length, ret;
uint8_t type = _type;
opaque preamble[PREAMBLE_SIZE];
int preamble_size;
int hash_size =
_gnutls_hash_get_algo_len (session->security_parameters.
write_mac_algorithm);
int blocksize =
gnutls_cipher_get_block_size (session->security_parameters.
write_bulk_cipher_algorithm);
cipher_type_t block_algo =
_gnutls_cipher_is_block (session->security_parameters.
write_bulk_cipher_algorithm);
opaque *data_ptr;
int ver = gnutls_protocol_get_version (session);
/* Initialize MAC */
c_length = _gnutls_conv_uint16 (compressed.size);
if (session->security_parameters.write_mac_algorithm != GNUTLS_MAC_NULL)
{ /* actually when the algorithm in not the NULL one */
digest_hd_st td;
ret = mac_init (&td, session->security_parameters.write_mac_algorithm,
session->connection_state.write_mac_secret.data,
session->connection_state.write_mac_secret.size, ver);
if (ret < 0)
{
gnutls_assert ();
return ret;
}
preamble_size = make_preamble( UINT64DATA (session->connection_state.write_sequence_number), type, c_length, ver, preamble);
mac_hash (&td, preamble, preamble_size, ver);
mac_hash (&td, compressed.data, compressed.size, ver);
mac_deinit (&td, MAC, ver);
}
/* Calculate the encrypted length (padding etc.)
*/
length =
calc_enc_length (session, compressed.size, hash_size, &pad,
random_pad, block_algo, blocksize);
if (length < 0)
{
gnutls_assert ();
return length;
}
/* copy the encrypted data to cipher_data.
*/
if (cipher_size < length)
{
gnutls_assert ();
return GNUTLS_E_MEMORY_ERROR;
}
data_ptr = cipher_data;
if (block_algo == CIPHER_BLOCK &&
_gnutls_version_has_explicit_iv (session->security_parameters.version))
{
/* copy the random IV.
*/
ret = _gnutls_rnd (GNUTLS_RND_NONCE, data_ptr, blocksize);
if (ret < 0)
{
gnutls_assert ();
return ret;
}
data_ptr += blocksize;
}
memcpy (data_ptr, compressed.data, compressed.size);
data_ptr += compressed.size;
if (hash_size > 0)
{
memcpy (data_ptr, MAC, hash_size);
data_ptr += hash_size;
}
if (block_algo == CIPHER_BLOCK && pad > 0)
{
memset (data_ptr, pad - 1, pad);
}
/* Actual encryption (inplace).
*/
ret =
_gnutls_cipher_encrypt (&session->connection_state.write_cipher_state,
cipher_data, length);
if (ret < 0)
{
gnutls_assert ();
return ret;
}
return length;
}
/* Deciphers the ciphertext packet, and puts the result to compress_data, of compress_size.
* Returns the actual compressed packet size.
*/
int
_gnutls_ciphertext2compressed (gnutls_session_t session,
opaque * compress_data,
int compress_size,
gnutls_datum_t ciphertext, uint8_t type)
{
uint8_t MAC[MAX_HASH_SIZE];
uint16_t c_length;
uint8_t pad;
int length;
uint16_t blocksize;
int ret, i, pad_failed = 0;
opaque preamble[PREAMBLE_SIZE];
int preamble_size;
int ver = gnutls_protocol_get_version (session);
int hash_size =
_gnutls_hash_get_algo_len (session->security_parameters.
read_mac_algorithm);
blocksize =
gnutls_cipher_get_block_size (session->security_parameters.
read_bulk_cipher_algorithm);
/* actual decryption (inplace)
*/
switch (_gnutls_cipher_is_block
(session->security_parameters.read_bulk_cipher_algorithm))
{
case CIPHER_STREAM:
if ((ret =
_gnutls_cipher_decrypt (&session->connection_state.
read_cipher_state, ciphertext.data,
ciphertext.size)) < 0)
{
gnutls_assert ();
return ret;
}
length = ciphertext.size - hash_size;
break;
case CIPHER_BLOCK:
if ((ciphertext.size < blocksize) || (ciphertext.size % blocksize != 0))
{
gnutls_assert ();
return GNUTLS_E_DECRYPTION_FAILED;
}
if ((ret =
_gnutls_cipher_decrypt (&session->connection_state.
read_cipher_state, ciphertext.data,
ciphertext.size)) < 0)
{
gnutls_assert ();
return ret;
}
/* ignore the IV in TLS 1.1.
*/
if (_gnutls_version_has_explicit_iv
(session->security_parameters.version))
{
ciphertext.size -= blocksize;
ciphertext.data += blocksize;
if (ciphertext.size == 0)
{
gnutls_assert ();
return GNUTLS_E_DECRYPTION_FAILED;
}
}
pad = ciphertext.data[ciphertext.size - 1] + 1; /* pad */
if ((int) pad > (int) ciphertext.size - hash_size)
{
gnutls_assert ();
_gnutls_record_log
("REC[%p]: Short record length %d > %d - %d (under attack?)\n",
session, pad, ciphertext.size, hash_size);
/* We do not fail here. We check below for the
* the pad_failed. If zero means success.
*/
pad_failed = GNUTLS_E_DECRYPTION_FAILED;
}
length = ciphertext.size - hash_size - pad;
/* Check the pading bytes (TLS 1.x)
*/
if (_gnutls_version_has_variable_padding (ver) && pad_failed == 0)
for (i = 2; i < pad; i++)
{
if (ciphertext.data[ciphertext.size - i] !=
ciphertext.data[ciphertext.size - 1])
pad_failed = GNUTLS_E_DECRYPTION_FAILED;
}
break;
default:
gnutls_assert ();
return GNUTLS_E_INTERNAL_ERROR;
}
if (length < 0)
length = 0;
c_length = _gnutls_conv_uint16 ((uint16_t) length);
/* Pass the type, version, length and compressed through
* MAC.
*/
if (session->security_parameters.read_mac_algorithm != GNUTLS_MAC_NULL)
{
digest_hd_st td;
ret = mac_init (&td, session->security_parameters.read_mac_algorithm,
session->connection_state.read_mac_secret.data,
session->connection_state.read_mac_secret.size, ver);
if (ret < 0)
{
gnutls_assert ();
return GNUTLS_E_INTERNAL_ERROR;
}
preamble_size = make_preamble( UINT64DATA (session->connection_state.read_sequence_number), type, c_length, ver, preamble);
mac_hash (&td, preamble, preamble_size, ver);
if (length > 0)
mac_hash (&td, ciphertext.data, length, ver);
mac_deinit (&td, MAC, ver);
}
/* This one was introduced to avoid a timing attack against the TLS
* 1.0 protocol.
*/
if (pad_failed != 0)
{
gnutls_assert ();
return pad_failed;
}
/* HMAC was not the same.
*/
if (memcmp (MAC, &ciphertext.data[length], hash_size) != 0)
{
gnutls_assert ();
return GNUTLS_E_DECRYPTION_FAILED;
}
/* copy the decrypted stuff to compress_data.
*/
if (compress_size < length)
{
gnutls_assert ();
return GNUTLS_E_DECOMPRESSION_FAILED;
}
memcpy (compress_data, ciphertext.data, length);
return length;
}
|