Google Git
Sign in
pigweed / third_party / github / ARMmbed / mbedtls / 10ba553c2e16e36c508cd263593c5b6099a37e08 / . / library / ssl_msg.c
blob: 51a0ac20511f9437fd1e2558ad7864f993727d8d [file] [log] [blame]
/*
* Generic SSL/TLS messaging layer functions
* (record layer + retransmission state machine)
*
* Copyright The Mbed TLS Contributors
* SPDX-License-Identifier: Apache-2.0
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may
* not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/*
* http://www.ietf.org/rfc/rfc2246.txt
* http://www.ietf.org/rfc/rfc4346.txt
*/
#include "common.h"
#if defined(MBEDTLS_SSL_TLS_C)
#if defined(MBEDTLS_PLATFORM_C)
#include "mbedtls/platform.h"
#else
#include <stdlib.h>
#define mbedtls_calloc calloc
#define mbedtls_free free
#endif
#include "mbedtls/ssl.h"
#include "ssl_misc.h"
#include "mbedtls/debug.h"
#include "mbedtls/error.h"
#include "mbedtls/platform_util.h"
#include "mbedtls/version.h"
#include "ssl_invasive.h"
#include <string.h>
#if defined(MBEDTLS_USE_PSA_CRYPTO)
#include "mbedtls/psa_util.h"
#include "psa/crypto.h"
#endif
#if defined(MBEDTLS_X509_CRT_PARSE_C)
#include "mbedtls/oid.h"
#endif
static uint32_t ssl_get_hs_total_len( mbedtls_ssl_context const *ssl );
/*
* Start a timer.
* Passing millisecs = 0 cancels a running timer.
*/
void mbedtls_ssl_set_timer( mbedtls_ssl_context *ssl, uint32_t millisecs )
{
if( ssl->f_set_timer == NULL )
return;
MBEDTLS_SSL_DEBUG_MSG( 3, ( "set_timer to %d ms", (int) millisecs ) );
ssl->f_set_timer( ssl->p_timer, millisecs / 4, millisecs );
}
/*
* Return -1 is timer is expired, 0 if it isn't.
*/
int mbedtls_ssl_check_timer( mbedtls_ssl_context *ssl )
{
if( ssl->f_get_timer == NULL )
return( 0 );
if( ssl->f_get_timer( ssl->p_timer ) == 2 )
{
MBEDTLS_SSL_DEBUG_MSG( 3, ( "timer expired" ) );
return( -1 );
}
return( 0 );
}
#if defined(MBEDTLS_SSL_RECORD_CHECKING)
static int ssl_parse_record_header( mbedtls_ssl_context const *ssl,
unsigned char *buf,
size_t len,
mbedtls_record *rec );
int mbedtls_ssl_check_record( mbedtls_ssl_context const *ssl,
unsigned char *buf,
size_t buflen )
{
int ret = 0;
MBEDTLS_SSL_DEBUG_MSG( 1, ( "=> mbedtls_ssl_check_record" ) );
MBEDTLS_SSL_DEBUG_BUF( 3, "record buffer", buf, buflen );
/* We don't support record checking in TLS because
* (a) there doesn't seem to be a usecase for it, and
* (b) In TLS 1.0, CBC record decryption has state
* and we'd need to backup the transform here.
*/
if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_STREAM )
{
ret = MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE;
goto exit;
}
#if defined(MBEDTLS_SSL_PROTO_DTLS)
else
{
mbedtls_record rec;
ret = ssl_parse_record_header( ssl, buf, buflen, &rec );
if( ret != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 3, "ssl_parse_record_header", ret );
goto exit;
}
if( ssl->transform_in != NULL )
{
ret = mbedtls_ssl_decrypt_buf( ssl, ssl->transform_in, &rec );
if( ret != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 3, "mbedtls_ssl_decrypt_buf", ret );
goto exit;
}
}
}
#endif /* MBEDTLS_SSL_PROTO_DTLS */
exit:
/* On success, we have decrypted the buffer in-place, so make
* sure we don't leak any plaintext data. */
mbedtls_platform_zeroize( buf, buflen );
/* For the purpose of this API, treat messages with unexpected CID
* as well as such from future epochs as unexpected. */
if( ret == MBEDTLS_ERR_SSL_UNEXPECTED_CID ||
ret == MBEDTLS_ERR_SSL_EARLY_MESSAGE )
{
ret = MBEDTLS_ERR_SSL_UNEXPECTED_RECORD;
}
MBEDTLS_SSL_DEBUG_MSG( 1, ( "<= mbedtls_ssl_check_record" ) );
return( ret );
}
#endif /* MBEDTLS_SSL_RECORD_CHECKING */
#define SSL_DONT_FORCE_FLUSH 0
#define SSL_FORCE_FLUSH 1
#if defined(MBEDTLS_SSL_PROTO_DTLS)
/* Forward declarations for functions related to message buffering. */
static void ssl_buffering_free_slot( mbedtls_ssl_context *ssl,
uint8_t slot );
static void ssl_free_buffered_record( mbedtls_ssl_context *ssl );
static int ssl_load_buffered_message( mbedtls_ssl_context *ssl );
static int ssl_load_buffered_record( mbedtls_ssl_context *ssl );
static int ssl_buffer_message( mbedtls_ssl_context *ssl );
static int ssl_buffer_future_record( mbedtls_ssl_context *ssl,
mbedtls_record const *rec );
static int ssl_next_record_is_in_datagram( mbedtls_ssl_context *ssl );
static size_t ssl_get_maximum_datagram_size( mbedtls_ssl_context const *ssl )
{
size_t mtu = mbedtls_ssl_get_current_mtu( ssl );
#if defined(MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH)
size_t out_buf_len = ssl->out_buf_len;
#else
size_t out_buf_len = MBEDTLS_SSL_OUT_BUFFER_LEN;
#endif
if( mtu != 0 && mtu < out_buf_len )
return( mtu );
return( out_buf_len );
}
static int ssl_get_remaining_space_in_datagram( mbedtls_ssl_context const *ssl )
{
size_t const bytes_written = ssl->out_left;
size_t const mtu = ssl_get_maximum_datagram_size( ssl );
/* Double-check that the write-index hasn't gone
* past what we can transmit in a single datagram. */
if( bytes_written > mtu )
{
/* Should never happen... */
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
}
return( (int) ( mtu - bytes_written ) );
}
static int ssl_get_remaining_payload_in_datagram( mbedtls_ssl_context const *ssl )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
size_t remaining, expansion;
size_t max_len = MBEDTLS_SSL_OUT_CONTENT_LEN;
#if defined(MBEDTLS_SSL_MAX_FRAGMENT_LENGTH)
const size_t mfl = mbedtls_ssl_get_output_max_frag_len( ssl );
if( max_len > mfl )
max_len = mfl;
/* By the standard (RFC 6066 Sect. 4), the MFL extension
* only limits the maximum record payload size, so in theory
* we would be allowed to pack multiple records of payload size
* MFL into a single datagram. However, this would mean that there's
* no way to explicitly communicate MTU restrictions to the peer.
*
* The following reduction of max_len makes sure that we never
* write datagrams larger than MFL + Record Expansion Overhead.
*/
if( max_len <= ssl->out_left )
return( 0 );
max_len -= ssl->out_left;
#endif
ret = ssl_get_remaining_space_in_datagram( ssl );
if( ret < 0 )
return( ret );
remaining = (size_t) ret;
ret = mbedtls_ssl_get_record_expansion( ssl );
if( ret < 0 )
return( ret );
expansion = (size_t) ret;
if( remaining <= expansion )
return( 0 );
remaining -= expansion;
if( remaining >= max_len )
remaining = max_len;
return( (int) remaining );
}
/*
* Double the retransmit timeout value, within the allowed range,
* returning -1 if the maximum value has already been reached.
*/
static int ssl_double_retransmit_timeout( mbedtls_ssl_context *ssl )
{
uint32_t new_timeout;
if( ssl->handshake->retransmit_timeout >= ssl->conf->hs_timeout_max )
return( -1 );
/* Implement the final paragraph of RFC 6347 section 4.1.1.1
* in the following way: after the initial transmission and a first
* retransmission, back off to a temporary estimated MTU of 508 bytes.
* This value is guaranteed to be deliverable (if not guaranteed to be
* delivered) of any compliant IPv4 (and IPv6) network, and should work
* on most non-IP stacks too. */
if( ssl->handshake->retransmit_timeout != ssl->conf->hs_timeout_min )
{
ssl->handshake->mtu = 508;
MBEDTLS_SSL_DEBUG_MSG( 2, ( "mtu autoreduction to %d bytes", ssl->handshake->mtu ) );
}
new_timeout = 2 * ssl->handshake->retransmit_timeout;
/* Avoid arithmetic overflow and range overflow */
if( new_timeout < ssl->handshake->retransmit_timeout ||
new_timeout > ssl->conf->hs_timeout_max )
{
new_timeout = ssl->conf->hs_timeout_max;
}
ssl->handshake->retransmit_timeout = new_timeout;
MBEDTLS_SSL_DEBUG_MSG( 3, ( "update timeout value to %lu millisecs",
(unsigned long) ssl->handshake->retransmit_timeout ) );
return( 0 );
}
static void ssl_reset_retransmit_timeout( mbedtls_ssl_context *ssl )
{
ssl->handshake->retransmit_timeout = ssl->conf->hs_timeout_min;
MBEDTLS_SSL_DEBUG_MSG( 3, ( "update timeout value to %lu millisecs",
(unsigned long) ssl->handshake->retransmit_timeout ) );
}
#endif /* MBEDTLS_SSL_PROTO_DTLS */
/*
* Encryption/decryption functions
*/
#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) || \
defined(MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL)
static size_t ssl_compute_padding_length( size_t len,
size_t granularity )
{
return( ( granularity - ( len + 1 ) % granularity ) % granularity );
}
/* This functions transforms a (D)TLS plaintext fragment and a record content
* type into an instance of the (D)TLSInnerPlaintext structure. This is used
* in DTLS 1.2 + CID and within TLS 1.3 to allow flexible padding and to protect
* a record's content type.
*
* struct {
* opaque content[DTLSPlaintext.length];
* ContentType real_type;
* uint8 zeros[length_of_padding];
* } (D)TLSInnerPlaintext;
*
* Input:
* - `content`: The beginning of the buffer holding the
* plaintext to be wrapped.
* - `*content_size`: The length of the plaintext in Bytes.
* - `max_len`: The number of Bytes available starting from
* `content`. This must be `>= *content_size`.
* - `rec_type`: The desired record content type.
*
* Output:
* - `content`: The beginning of the resulting (D)TLSInnerPlaintext structure.
* - `*content_size`: The length of the resulting (D)TLSInnerPlaintext structure.
*
* Returns:
* - `0` on success.
* - A negative error code if `max_len` didn't offer enough space
* for the expansion.
*/
static int ssl_build_inner_plaintext( unsigned char *content,
size_t *content_size,
size_t remaining,
uint8_t rec_type,
size_t pad )
{
size_t len = *content_size;
/* Write real content type */
if( remaining == 0 )
return( -1 );
content[ len ] = rec_type;
len++;
remaining--;
if( remaining < pad )
return( -1 );
memset( content + len, 0, pad );
len += pad;
remaining -= pad;
*content_size = len;
return( 0 );
}
/* This function parses a (D)TLSInnerPlaintext structure.
* See ssl_build_inner_plaintext() for details. */
static int ssl_parse_inner_plaintext( unsigned char const *content,
size_t *content_size,
uint8_t *rec_type )
{
size_t remaining = *content_size;
/* Determine length of padding by skipping zeroes from the back. */
do
{
if( remaining == 0 )
return( -1 );
remaining--;
} while( content[ remaining ] == 0 );
*content_size = remaining;
*rec_type = content[ remaining ];
return( 0 );
}
#endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID ||
MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */
/* `add_data` must have size 13 Bytes if the CID extension is disabled,
* and 13 + 1 + CID-length Bytes if the CID extension is enabled. */
static void ssl_extract_add_data_from_record( unsigned char* add_data,
size_t *add_data_len,
mbedtls_record *rec,
unsigned minor_ver )
{
/* Quoting RFC 5246 (TLS 1.2):
*
* additional_data = seq_num + TLSCompressed.type +
* TLSCompressed.version + TLSCompressed.length;
*
* For the CID extension, this is extended as follows
* (quoting draft-ietf-tls-dtls-connection-id-05,
* https://tools.ietf.org/html/draft-ietf-tls-dtls-connection-id-05):
*
* additional_data = seq_num + DTLSPlaintext.type +
* DTLSPlaintext.version +
* cid +
* cid_length +
* length_of_DTLSInnerPlaintext;
*
* For TLS 1.3, the record sequence number is dropped from the AAD
* and encoded within the nonce of the AEAD operation instead.
*/
unsigned char *cur = add_data;
#if defined(MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL)
if( minor_ver != MBEDTLS_SSL_MINOR_VERSION_4 )
#endif /* MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */
{
((void) minor_ver);
memcpy( cur, rec->ctr, sizeof( rec->ctr ) );
cur += sizeof( rec->ctr );
}
*cur = rec->type;
cur++;
memcpy( cur, rec->ver, sizeof( rec->ver ) );
cur += sizeof( rec->ver );
#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
if( rec->cid_len != 0 )
{
memcpy( cur, rec->cid, rec->cid_len );
cur += rec->cid_len;
*cur = rec->cid_len;
cur++;
cur[0] = ( rec->data_len >> 8 ) & 0xFF;
cur[1] = ( rec->data_len >> 0 ) & 0xFF;
cur += 2;
}
else
#endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
{
cur[0] = ( rec->data_len >> 8 ) & 0xFF;
cur[1] = ( rec->data_len >> 0 ) & 0xFF;
cur += 2;
}
*add_data_len = cur - add_data;
}
#if defined(MBEDTLS_GCM_C) || \
defined(MBEDTLS_CCM_C) || \
defined(MBEDTLS_CHACHAPOLY_C)
static int ssl_transform_aead_dynamic_iv_is_explicit(
mbedtls_ssl_transform const *transform )
{
return( transform->ivlen != transform->fixed_ivlen );
}
/* Compute IV := ( fixed_iv || 0 ) XOR ( 0 || dynamic_IV )
*
* Concretely, this occurs in two variants:
*
* a) Fixed and dynamic IV lengths add up to total IV length, giving
* IV = fixed_iv || dynamic_iv
*
* This variant is used in TLS 1.2 when used with GCM or CCM.
*
* b) Fixed IV lengths matches total IV length, giving
* IV = fixed_iv XOR ( 0 || dynamic_iv )
*
* This variant occurs in TLS 1.3 and for TLS 1.2 when using ChaChaPoly.
*
* See also the documentation of mbedtls_ssl_transform.
*
* This function has the precondition that
*
* dst_iv_len >= max( fixed_iv_len, dynamic_iv_len )
*
* which has to be ensured by the caller. If this precondition
* violated, the behavior of this function is undefined.
*/
static void ssl_build_record_nonce( unsigned char *dst_iv,
size_t dst_iv_len,
unsigned char const *fixed_iv,
size_t fixed_iv_len,
unsigned char const *dynamic_iv,
size_t dynamic_iv_len )
{
size_t i;
/* Start with Fixed IV || 0 */
memset( dst_iv, 0, dst_iv_len );
memcpy( dst_iv, fixed_iv, fixed_iv_len );
dst_iv += dst_iv_len - dynamic_iv_len;
for( i = 0; i < dynamic_iv_len; i++ )
dst_iv[i] ^= dynamic_iv[i];
}
#endif /* MBEDTLS_GCM_C || MBEDTLS_CCM_C || MBEDTLS_CHACHAPOLY_C */
int mbedtls_ssl_encrypt_buf( mbedtls_ssl_context *ssl,
mbedtls_ssl_transform *transform,
mbedtls_record *rec,
int (*f_rng)(void *, unsigned char *, size_t),
void *p_rng )
{
mbedtls_cipher_mode_t mode;
int auth_done = 0;
unsigned char * data;
unsigned char add_data[13 + 1 + MBEDTLS_SSL_CID_OUT_LEN_MAX ];
size_t add_data_len;
size_t post_avail;
/* The SSL context is only used for debugging purposes! */
#if !defined(MBEDTLS_DEBUG_C)
ssl = NULL; /* make sure we don't use it except for debug */
((void) ssl);
#endif
/* The PRNG is used for dynamic IV generation that's used
* for CBC transformations in TLS 1.1 and TLS 1.2. */
#if !( defined(MBEDTLS_SSL_SOME_SUITES_USE_CBC) && \
( defined(MBEDTLS_SSL_PROTO_TLS1_1) || defined(MBEDTLS_SSL_PROTO_TLS1_2) ) )
((void) f_rng);
((void) p_rng);
#endif
MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> encrypt buf" ) );
if( transform == NULL )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "no transform provided to encrypt_buf" ) );
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
}
if( rec == NULL
|| rec->buf == NULL
|| rec->buf_len < rec->data_offset
|| rec->buf_len - rec->data_offset < rec->data_len
#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
|| rec->cid_len != 0
#endif
)
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad record structure provided to encrypt_buf" ) );
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
}
data = rec->buf + rec->data_offset;
post_avail = rec->buf_len - ( rec->data_len + rec->data_offset );
MBEDTLS_SSL_DEBUG_BUF( 4, "before encrypt: output payload",
data, rec->data_len );
mode = mbedtls_cipher_get_cipher_mode( &transform->cipher_ctx_enc );
if( rec->data_len > MBEDTLS_SSL_OUT_CONTENT_LEN )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "Record content %" MBEDTLS_PRINTF_SIZET
" too large, maximum %" MBEDTLS_PRINTF_SIZET,
rec->data_len,
(size_t) MBEDTLS_SSL_OUT_CONTENT_LEN ) );
return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
}
/* The following two code paths implement the (D)TLSInnerPlaintext
* structure present in TLS 1.3 and DTLS 1.2 + CID.
*
* See ssl_build_inner_plaintext() for more information.
*
* Note that this changes `rec->data_len`, and hence
* `post_avail` needs to be recalculated afterwards.
*
* Note also that the two code paths cannot occur simultaneously
* since they apply to different versions of the protocol. There
* is hence no risk of double-addition of the inner plaintext.
*/
#if defined(MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL)
if( transform->minor_ver == MBEDTLS_SSL_MINOR_VERSION_4 )
{
size_t padding =
ssl_compute_padding_length( rec->data_len,
MBEDTLS_SSL_TLS1_3_PADDING_GRANULARITY );
if( ssl_build_inner_plaintext( data,
&rec->data_len,
post_avail,
rec->type,
padding ) != 0 )
{
return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL );
}
rec->type = MBEDTLS_SSL_MSG_APPLICATION_DATA;
}
#endif /* MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */
#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
/*
* Add CID information
*/
rec->cid_len = transform->out_cid_len;
memcpy( rec->cid, transform->out_cid, transform->out_cid_len );
MBEDTLS_SSL_DEBUG_BUF( 3, "CID", rec->cid, rec->cid_len );
if( rec->cid_len != 0 )
{
size_t padding =
ssl_compute_padding_length( rec->data_len,
MBEDTLS_SSL_CID_PADDING_GRANULARITY );
/*
* Wrap plaintext into DTLSInnerPlaintext structure.
* See ssl_build_inner_plaintext() for more information.
*
* Note that this changes `rec->data_len`, and hence
* `post_avail` needs to be recalculated afterwards.
*/
if( ssl_build_inner_plaintext( data,
&rec->data_len,
post_avail,
rec->type,
padding ) != 0 )
{
return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL );
}
rec->type = MBEDTLS_SSL_MSG_CID;
}
#endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
post_avail = rec->buf_len - ( rec->data_len + rec->data_offset );
/*
* Add MAC before if needed
*/
#if defined(MBEDTLS_SSL_SOME_MODES_USE_MAC)
if( mode == MBEDTLS_MODE_STREAM ||
( mode == MBEDTLS_MODE_CBC
#if defined(MBEDTLS_SSL_ENCRYPT_THEN_MAC)
&& transform->encrypt_then_mac == MBEDTLS_SSL_ETM_DISABLED
#endif
) )
{
if( post_avail < transform->maclen )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "Buffer provided for encrypted record not large enough" ) );
return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL );
}
#if defined(MBEDTLS_SSL_PROTO_TLS1) || defined(MBEDTLS_SSL_PROTO_TLS1_1) || \
defined(MBEDTLS_SSL_PROTO_TLS1_2)
if( transform->minor_ver >= MBEDTLS_SSL_MINOR_VERSION_1 )
{
unsigned char mac[MBEDTLS_SSL_MAC_ADD];
ssl_extract_add_data_from_record( add_data, &add_data_len, rec,
transform->minor_ver );
mbedtls_md_hmac_update( &transform->md_ctx_enc, add_data,
add_data_len );
mbedtls_md_hmac_update( &transform->md_ctx_enc,
data, rec->data_len );
mbedtls_md_hmac_finish( &transform->md_ctx_enc, mac );
mbedtls_md_hmac_reset( &transform->md_ctx_enc );
memcpy( data + rec->data_len, mac, transform->maclen );
}
else
#endif
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
}
MBEDTLS_SSL_DEBUG_BUF( 4, "computed mac", data + rec->data_len,
transform->maclen );
rec->data_len += transform->maclen;
post_avail -= transform->maclen;
auth_done++;
}
#endif /* MBEDTLS_SSL_SOME_MODES_USE_MAC */
/*
* Encrypt
*/
#if defined(MBEDTLS_CIPHER_NULL_CIPHER)
if( mode == MBEDTLS_MODE_STREAM )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
size_t olen;
MBEDTLS_SSL_DEBUG_MSG( 3, ( "before encrypt: msglen = %" MBEDTLS_PRINTF_SIZET ", "
"including %d bytes of padding",
rec->data_len, 0 ) );
if( ( ret = mbedtls_cipher_crypt( &transform->cipher_ctx_enc,
transform->iv_enc, transform->ivlen,
data, rec->data_len,
data, &olen ) ) != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_cipher_crypt", ret );
return( ret );
}
if( rec->data_len != olen )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
}
}
else
#endif /* MBEDTLS_CIPHER_NULL_CIPHER */
#if defined(MBEDTLS_GCM_C) || \
defined(MBEDTLS_CCM_C) || \
defined(MBEDTLS_CHACHAPOLY_C)
if( mode == MBEDTLS_MODE_GCM ||
mode == MBEDTLS_MODE_CCM ||
mode == MBEDTLS_MODE_CHACHAPOLY )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
unsigned char iv[12];
unsigned char *dynamic_iv;
size_t dynamic_iv_len;
int dynamic_iv_is_explicit =
ssl_transform_aead_dynamic_iv_is_explicit( transform );
/* Check that there's space for the authentication tag. */
if( post_avail < transform->taglen )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "Buffer provided for encrypted record not large enough" ) );
return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL );
}
/*
* Build nonce for AEAD encryption.
*
* Note: In the case of CCM and GCM in TLS 1.2, the dynamic
* part of the IV is prepended to the ciphertext and
* can be chosen freely - in particular, it need not
* agree with the record sequence number.
* However, since ChaChaPoly as well as all AEAD modes
* in TLS 1.3 use the record sequence number as the
* dynamic part of the nonce, we uniformly use the
* record sequence number here in all cases.
*/
dynamic_iv = rec->ctr;
dynamic_iv_len = sizeof( rec->ctr );
ssl_build_record_nonce( iv, sizeof( iv ),
transform->iv_enc,
transform->fixed_ivlen,
dynamic_iv,
dynamic_iv_len );
/*
* Build additional data for AEAD encryption.
* This depends on the TLS version.
*/
ssl_extract_add_data_from_record( add_data, &add_data_len, rec,
transform->minor_ver );
MBEDTLS_SSL_DEBUG_BUF( 4, "IV used (internal)",
iv, transform->ivlen );
MBEDTLS_SSL_DEBUG_BUF( 4, "IV used (transmitted)",
dynamic_iv,
dynamic_iv_is_explicit ? dynamic_iv_len : 0 );
MBEDTLS_SSL_DEBUG_BUF( 4, "additional data used for AEAD",
add_data, add_data_len );
MBEDTLS_SSL_DEBUG_MSG( 3, ( "before encrypt: msglen = %" MBEDTLS_PRINTF_SIZET ", "
"including 0 bytes of padding",
rec->data_len ) );
/*
* Encrypt and authenticate
*/
if( ( ret = mbedtls_cipher_auth_encrypt_ext( &transform->cipher_ctx_enc,
iv, transform->ivlen,
add_data, add_data_len,
data, rec->data_len, /* src */
data, rec->buf_len - (data - rec->buf), /* dst */
&rec->data_len,
transform->taglen ) ) != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_cipher_auth_encrypt", ret );
return( ret );
}
MBEDTLS_SSL_DEBUG_BUF( 4, "after encrypt: tag",
data + rec->data_len - transform->taglen,
transform->taglen );
/* Account for authentication tag. */
post_avail -= transform->taglen;
/*
* Prefix record content with dynamic IV in case it is explicit.
*/
if( dynamic_iv_is_explicit != 0 )
{
if( rec->data_offset < dynamic_iv_len )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "Buffer provided for encrypted record not large enough" ) );
return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL );
}
memcpy( data - dynamic_iv_len, dynamic_iv, dynamic_iv_len );
rec->data_offset -= dynamic_iv_len;
rec->data_len += dynamic_iv_len;
}
auth_done++;
}
else
#endif /* MBEDTLS_GCM_C || MBEDTLS_CCM_C || MBEDTLS_CHACHAPOLY_C */
#if defined(MBEDTLS_SSL_SOME_SUITES_USE_CBC)
if( mode == MBEDTLS_MODE_CBC )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
size_t padlen, i;
size_t olen;
/* Currently we're always using minimal padding
* (up to 255 bytes would be allowed). */
padlen = transform->ivlen - ( rec->data_len + 1 ) % transform->ivlen;
if( padlen == transform->ivlen )
padlen = 0;
/* Check there's enough space in the buffer for the padding. */
if( post_avail < padlen + 1 )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "Buffer provided for encrypted record not large enough" ) );
return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL );
}
for( i = 0; i <= padlen; i++ )
data[rec->data_len + i] = (unsigned char) padlen;
rec->data_len += padlen + 1;
post_avail -= padlen + 1;
#if defined(MBEDTLS_SSL_PROTO_TLS1_1) || defined(MBEDTLS_SSL_PROTO_TLS1_2)
/*
* Prepend per-record IV for block cipher in TLS v1.1 and up as per
* Method 1 (6.2.3.2. in RFC4346 and RFC5246)
*/
if( transform->minor_ver >= MBEDTLS_SSL_MINOR_VERSION_2 )
{
if( f_rng == NULL )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "No PRNG provided to encrypt_record routine" ) );
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
}
if( rec->data_offset < transform->ivlen )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "Buffer provided for encrypted record not large enough" ) );
return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL );
}
/*
* Generate IV
*/
ret = f_rng( p_rng, transform->iv_enc, transform->ivlen );
if( ret != 0 )
return( ret );
memcpy( data - transform->ivlen, transform->iv_enc,
transform->ivlen );
}
#endif /* MBEDTLS_SSL_PROTO_TLS1_1 || MBEDTLS_SSL_PROTO_TLS1_2 */
MBEDTLS_SSL_DEBUG_MSG( 3, ( "before encrypt: msglen = %" MBEDTLS_PRINTF_SIZET ", "
"including %" MBEDTLS_PRINTF_SIZET
" bytes of IV and %" MBEDTLS_PRINTF_SIZET " bytes of padding",
rec->data_len, transform->ivlen,
padlen + 1 ) );
if( ( ret = mbedtls_cipher_crypt( &transform->cipher_ctx_enc,
transform->iv_enc,
transform->ivlen,
data, rec->data_len,
data, &olen ) ) != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_cipher_crypt", ret );
return( ret );
}
if( rec->data_len != olen )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
}
#if defined(MBEDTLS_SSL_PROTO_TLS1)
if( transform->minor_ver < MBEDTLS_SSL_MINOR_VERSION_2 )
{
/*
* Save IV in TLS1
*/
memcpy( transform->iv_enc, transform->cipher_ctx_enc.iv,
transform->ivlen );
}
else
#endif
{
data -= transform->ivlen;
rec->data_offset -= transform->ivlen;
rec->data_len += transform->ivlen;
}
#if defined(MBEDTLS_SSL_ENCRYPT_THEN_MAC)
if( auth_done == 0 )
{
unsigned char mac[MBEDTLS_SSL_MAC_ADD];
/*
* MAC(MAC_write_key, seq_num +
* TLSCipherText.type +
* TLSCipherText.version +
* length_of( (IV +) ENC(...) ) +
* IV + // except for TLS 1.0
* ENC(content + padding + padding_length));
*/
if( post_avail < transform->maclen)
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "Buffer provided for encrypted record not large enough" ) );
return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL );
}
ssl_extract_add_data_from_record( add_data, &add_data_len,
rec, transform->minor_ver );
MBEDTLS_SSL_DEBUG_MSG( 3, ( "using encrypt then mac" ) );
MBEDTLS_SSL_DEBUG_BUF( 4, "MAC'd meta-data", add_data,
add_data_len );
mbedtls_md_hmac_update( &transform->md_ctx_enc, add_data,
add_data_len );
mbedtls_md_hmac_update( &transform->md_ctx_enc,
data, rec->data_len );
mbedtls_md_hmac_finish( &transform->md_ctx_enc, mac );
mbedtls_md_hmac_reset( &transform->md_ctx_enc );
memcpy( data + rec->data_len, mac, transform->maclen );
rec->data_len += transform->maclen;
post_avail -= transform->maclen;
auth_done++;
}
#endif /* MBEDTLS_SSL_ENCRYPT_THEN_MAC */
}
else
#endif /* MBEDTLS_SSL_SOME_SUITES_USE_CBC) */
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
}
/* Make extra sure authentication was performed, exactly once */
if( auth_done != 1 )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
}
MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= encrypt buf" ) );
return( 0 );
}
#if defined(MBEDTLS_SSL_SOME_SUITES_USE_TLS_CBC)
/*
* Turn a bit into a mask:
* - if bit == 1, return the all-bits 1 mask, aka (size_t) -1
* - if bit == 0, return the all-bits 0 mask, aka 0
*
* This function can be used to write constant-time code by replacing branches
* with bit operations using masks.
*
* This function is implemented without using comparison operators, as those
* might be translated to branches by some compilers on some platforms.
*/
static size_t mbedtls_ssl_cf_mask_from_bit( size_t bit )
{
/* MSVC has a warning about unary minus on unsigned integer types,
* but this is well-defined and precisely what we want to do here. */
#if defined(_MSC_VER)
#pragma warning( push )
#pragma warning( disable : 4146 )
#endif
return -bit;
#if defined(_MSC_VER)
#pragma warning( pop )
#endif
}
/*
* Constant-flow mask generation for "less than" comparison:
* - if x < y, return all bits 1, that is (size_t) -1
* - otherwise, return all bits 0, that is 0
*
* This function can be used to write constant-time code by replacing branches
* with bit operations using masks.
*
* This function is implemented without using comparison operators, as those
* might be translated to branches by some compilers on some platforms.
*/
static size_t mbedtls_ssl_cf_mask_lt( size_t x, size_t y )
{
/* This has the most significant bit set if and only if x < y */
const size_t sub = x - y;
/* sub1 = (x < y) ? 1 : 0 */
const size_t sub1 = sub >> ( sizeof( sub ) * 8 - 1 );
/* mask = (x < y) ? 0xff... : 0x00... */
const size_t mask = mbedtls_ssl_cf_mask_from_bit( sub1 );
return( mask );
}
/*
* Constant-flow mask generation for "greater or equal" comparison:
* - if x >= y, return all bits 1, that is (size_t) -1
* - otherwise, return all bits 0, that is 0
*
* This function can be used to write constant-time code by replacing branches
* with bit operations using masks.
*
* This function is implemented without using comparison operators, as those
* might be translated to branches by some compilers on some platforms.
*/
static size_t mbedtls_ssl_cf_mask_ge( size_t x, size_t y )
{
return( ~mbedtls_ssl_cf_mask_lt( x, y ) );
}
/*
* Constant-flow boolean "equal" comparison:
* return x == y
*
* This function can be used to write constant-time code by replacing branches
* with bit operations - it can be used in conjunction with
* mbedtls_ssl_cf_mask_from_bit().
*
* This function is implemented without using comparison operators, as those
* might be translated to branches by some compilers on some platforms.
*/
static size_t mbedtls_ssl_cf_bool_eq( size_t x, size_t y )
{
/* diff = 0 if x == y, non-zero otherwise */
const size_t diff = x ^ y;
/* MSVC has a warning about unary minus on unsigned integer types,
* but this is well-defined and precisely what we want to do here. */
#if defined(_MSC_VER)
#pragma warning( push )
#pragma warning( disable : 4146 )
#endif
/* diff_msb's most significant bit is equal to x != y */
const size_t diff_msb = ( diff | -diff );
#if defined(_MSC_VER)
#pragma warning( pop )
#endif
/* diff1 = (x != y) ? 1 : 0 */
const size_t diff1 = diff_msb >> ( sizeof( diff_msb ) * 8 - 1 );
return( 1 ^ diff1 );
}
/*
* Constant-flow conditional memcpy:
* - if c1 == c2, equivalent to memcpy(dst, src, len),
* - otherwise, a no-op,
* but with execution flow independent of the values of c1 and c2.
*
* This function is implemented without using comparison operators, as those
* might be translated to branches by some compilers on some platforms.
*/
static void mbedtls_ssl_cf_memcpy_if_eq( unsigned char *dst,
const unsigned char *src,
size_t len,
size_t c1, size_t c2 )
{
/* mask = c1 == c2 ? 0xff : 0x00 */
const size_t equal = mbedtls_ssl_cf_bool_eq( c1, c2 );
const unsigned char mask = (unsigned char) mbedtls_ssl_cf_mask_from_bit( equal );
/* dst[i] = c1 == c2 ? src[i] : dst[i] */
for( size_t i = 0; i < len; i++ )
dst[i] = ( src[i] & mask ) | ( dst[i] & ~mask );
}
/*
* Compute HMAC of variable-length data with constant flow.
*
* Only works with MD-5, SHA-1, SHA-256 and SHA-384.
* (Otherwise, computation of block_size needs to be adapted.)
*/
MBEDTLS_STATIC_TESTABLE int mbedtls_ssl_cf_hmac(
mbedtls_md_context_t *ctx,
const unsigned char *add_data, size_t add_data_len,
const unsigned char *data, size_t data_len_secret,
size_t min_data_len, size_t max_data_len,
unsigned char *output )
{
/*
* This function breaks the HMAC abstraction and uses the md_clone()
* extension to the MD API in order to get constant-flow behaviour.
*
* HMAC(msg) is defined as HASH(okey + HASH(ikey + msg)) where + means
* concatenation, and okey/ikey are the XOR of the key with some fixed bit
* patterns (see RFC 2104, sec. 2), which are stored in ctx->hmac_ctx.
*
* We'll first compute inner_hash = HASH(ikey + msg) by hashing up to
* minlen, then cloning the context, and for each byte up to maxlen
* finishing up the hash computation, keeping only the correct result.
*
* Then we only need to compute HASH(okey + inner_hash) and we're done.
*/
const mbedtls_md_type_t md_alg = mbedtls_md_get_type( ctx->md_info );
/* TLS 1.0-1.2 only support SHA-384, SHA-256, SHA-1, MD-5,
* all of which have the same block size except SHA-384. */
const size_t block_size = md_alg == MBEDTLS_MD_SHA384 ? 128 : 64;
const unsigned char * const ikey = ctx->hmac_ctx;
const unsigned char * const okey = ikey + block_size;
const size_t hash_size = mbedtls_md_get_size( ctx->md_info );
unsigned char aux_out[MBEDTLS_MD_MAX_SIZE];
mbedtls_md_context_t aux;
size_t offset;
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
mbedtls_md_init( &aux );
#define MD_CHK( func_call ) \
do { \
ret = (func_call); \
if( ret != 0 ) \
goto cleanup; \
} while( 0 )
MD_CHK( mbedtls_md_setup( &aux, ctx->md_info, 0 ) );
/* After hmac_start() of hmac_reset(), ikey has already been hashed,
* so we can start directly with the message */
MD_CHK( mbedtls_md_update( ctx, add_data, add_data_len ) );
MD_CHK( mbedtls_md_update( ctx, data, min_data_len ) );
/* For each possible length, compute the hash up to that point */
for( offset = min_data_len; offset <= max_data_len; offset++ )
{
MD_CHK( mbedtls_md_clone( &aux, ctx ) );
MD_CHK( mbedtls_md_finish( &aux, aux_out ) );
/* Keep only the correct inner_hash in the output buffer */
mbedtls_ssl_cf_memcpy_if_eq( output, aux_out, hash_size,
offset, data_len_secret );
if( offset < max_data_len )
MD_CHK( mbedtls_md_update( ctx, data + offset, 1 ) );
}
/* Now compute HASH(okey + inner_hash) */
MD_CHK( mbedtls_md_starts( ctx ) );
MD_CHK( mbedtls_md_update( ctx, okey, block_size ) );
MD_CHK( mbedtls_md_update( ctx, output, hash_size ) );
MD_CHK( mbedtls_md_finish( ctx, output ) );
/* Done, get ready for next time */
MD_CHK( mbedtls_md_hmac_reset( ctx ) );
#undef MD_CHK
cleanup:
mbedtls_md_free( &aux );
return( ret );
}
/*
* Constant-flow memcpy from variable position in buffer.
* - functionally equivalent to memcpy(dst, src + offset_secret, len)
* - but with execution flow independent from the value of offset_secret.
*/
MBEDTLS_STATIC_TESTABLE void mbedtls_ssl_cf_memcpy_offset(
unsigned char *dst,
const unsigned char *src_base,
size_t offset_secret,
size_t offset_min, size_t offset_max,
size_t len )
{
size_t offset;
for( offset = offset_min; offset <= offset_max; offset++ )
{
mbedtls_ssl_cf_memcpy_if_eq( dst, src_base + offset, len,
offset, offset_secret );
}
}
#endif /* MBEDTLS_SSL_SOME_SUITES_USE_TLS_CBC */
int mbedtls_ssl_decrypt_buf( mbedtls_ssl_context const *ssl,
mbedtls_ssl_transform *transform,
mbedtls_record *rec )
{
size_t olen;
mbedtls_cipher_mode_t mode;
int ret, auth_done = 0;
#if defined(MBEDTLS_SSL_SOME_MODES_USE_MAC)
size_t padlen = 0, correct = 1;
#endif
unsigned char* data;
unsigned char add_data[13 + 1 + MBEDTLS_SSL_CID_IN_LEN_MAX ];
size_t add_data_len;
#if !defined(MBEDTLS_DEBUG_C)
ssl = NULL; /* make sure we don't use it except for debug */
((void) ssl);
#endif
MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> decrypt buf" ) );
if( rec == NULL ||
rec->buf == NULL ||
rec->buf_len < rec->data_offset ||
rec->buf_len - rec->data_offset < rec->data_len )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad record structure provided to decrypt_buf" ) );
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
}
data = rec->buf + rec->data_offset;
mode = mbedtls_cipher_get_cipher_mode( &transform->cipher_ctx_dec );
#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
/*
* Match record's CID with incoming CID.
*/
if( rec->cid_len != transform->in_cid_len ||
memcmp( rec->cid, transform->in_cid, rec->cid_len ) != 0 )
{
return( MBEDTLS_ERR_SSL_UNEXPECTED_CID );
}
#endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
#if defined(MBEDTLS_CIPHER_NULL_CIPHER)
if( mode == MBEDTLS_MODE_STREAM )
{
padlen = 0;
if( ( ret = mbedtls_cipher_crypt( &transform->cipher_ctx_dec,
transform->iv_dec,
transform->ivlen,
data, rec->data_len,
data, &olen ) ) != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_cipher_crypt", ret );
return( ret );
}
if( rec->data_len != olen )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
}
}
else
#endif /* MBEDTLS_CIPHER_NULL_CIPHER */
#if defined(MBEDTLS_GCM_C) || \
defined(MBEDTLS_CCM_C) || \
defined(MBEDTLS_CHACHAPOLY_C)
if( mode == MBEDTLS_MODE_GCM ||
mode == MBEDTLS_MODE_CCM ||
mode == MBEDTLS_MODE_CHACHAPOLY )
{
unsigned char iv[12];
unsigned char *dynamic_iv;
size_t dynamic_iv_len;
/*
* Extract dynamic part of nonce for AEAD decryption.
*
* Note: In the case of CCM and GCM in TLS 1.2, the dynamic
* part of the IV is prepended to the ciphertext and
* can be chosen freely - in particular, it need not
* agree with the record sequence number.
*/
dynamic_iv_len = sizeof( rec->ctr );
if( ssl_transform_aead_dynamic_iv_is_explicit( transform ) == 1 )
{
if( rec->data_len < dynamic_iv_len )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "msglen (%" MBEDTLS_PRINTF_SIZET
" ) < explicit_iv_len (%" MBEDTLS_PRINTF_SIZET ") ",
rec->data_len,
dynamic_iv_len ) );
return( MBEDTLS_ERR_SSL_INVALID_MAC );
}
dynamic_iv = data;
data += dynamic_iv_len;
rec->data_offset += dynamic_iv_len;
rec->data_len -= dynamic_iv_len;
}
else
{
dynamic_iv = rec->ctr;
}
/* Check that there's space for the authentication tag. */
if( rec->data_len < transform->taglen )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "msglen (%" MBEDTLS_PRINTF_SIZET
") < taglen (%" MBEDTLS_PRINTF_SIZET ") ",
rec->data_len,
transform->taglen ) );
return( MBEDTLS_ERR_SSL_INVALID_MAC );
}
rec->data_len -= transform->taglen;
/*
* Prepare nonce from dynamic and static parts.
*/
ssl_build_record_nonce( iv, sizeof( iv ),
transform->iv_dec,
transform->fixed_ivlen,
dynamic_iv,
dynamic_iv_len );
/*
* Build additional data for AEAD encryption.
* This depends on the TLS version.
*/
ssl_extract_add_data_from_record( add_data, &add_data_len, rec,
transform->minor_ver );
MBEDTLS_SSL_DEBUG_BUF( 4, "additional data used for AEAD",
add_data, add_data_len );
/* Because of the check above, we know that there are
* explicit_iv_len Bytes preceeding data, and taglen
* bytes following data + data_len. This justifies
* the debug message and the invocation of
* mbedtls_cipher_auth_decrypt() below. */
MBEDTLS_SSL_DEBUG_BUF( 4, "IV used", iv, transform->ivlen );
MBEDTLS_SSL_DEBUG_BUF( 4, "TAG used", data + rec->data_len,
transform->taglen );
/*
* Decrypt and authenticate
*/
if( ( ret = mbedtls_cipher_auth_decrypt_ext( &transform->cipher_ctx_dec,
iv, transform->ivlen,
add_data, add_data_len,
data, rec->data_len + transform->taglen, /* src */
data, rec->buf_len - (data - rec->buf), &olen, /* dst */
transform->taglen ) ) != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_cipher_auth_decrypt", ret );
if( ret == MBEDTLS_ERR_CIPHER_AUTH_FAILED )
return( MBEDTLS_ERR_SSL_INVALID_MAC );
return( ret );
}
auth_done++;
/* Double-check that AEAD decryption doesn't change content length. */
if( olen != rec->data_len )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
}
}
else
#endif /* MBEDTLS_GCM_C || MBEDTLS_CCM_C */
#if defined(MBEDTLS_SSL_SOME_SUITES_USE_CBC)
if( mode == MBEDTLS_MODE_CBC )
{
size_t minlen = 0;
/*
* Check immediate ciphertext sanity
*/
#if defined(MBEDTLS_SSL_PROTO_TLS1_1) || defined(MBEDTLS_SSL_PROTO_TLS1_2)
if( transform->minor_ver >= MBEDTLS_SSL_MINOR_VERSION_2 )
{
/* The ciphertext is prefixed with the CBC IV. */
minlen += transform->ivlen;
}
#endif
/* Size considerations:
*
* - The CBC cipher text must not be empty and hence
* at least of size transform->ivlen.
*
* Together with the potential IV-prefix, this explains
* the first of the two checks below.
*
* - The record must contain a MAC, either in plain or
* encrypted, depending on whether Encrypt-then-MAC
* is used or not.
* - If it is, the message contains the IV-prefix,
* the CBC ciphertext, and the MAC.
* - If it is not, the padded plaintext, and hence
* the CBC ciphertext, has at least length maclen + 1
* because there is at least the padding length byte.
*
* As the CBC ciphertext is not empty, both cases give the
* lower bound minlen + maclen + 1 on the record size, which
* we test for in the second check below.
*/
if( rec->data_len < minlen + transform->ivlen ||
rec->data_len < minlen + transform->maclen + 1 )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "msglen (%" MBEDTLS_PRINTF_SIZET
") < max( ivlen(%" MBEDTLS_PRINTF_SIZET
"), maclen (%" MBEDTLS_PRINTF_SIZET ") "
"+ 1 ) ( + expl IV )", rec->data_len,
transform->ivlen,
transform->maclen ) );
return( MBEDTLS_ERR_SSL_INVALID_MAC );
}
/*
* Authenticate before decrypt if enabled
*/
#if defined(MBEDTLS_SSL_ENCRYPT_THEN_MAC)
if( transform->encrypt_then_mac == MBEDTLS_SSL_ETM_ENABLED )
{
unsigned char mac_expect[MBEDTLS_SSL_MAC_ADD];
MBEDTLS_SSL_DEBUG_MSG( 3, ( "using encrypt then mac" ) );
/* Update data_len in tandem with add_data.
*
* The subtraction is safe because of the previous check
* data_len >= minlen + maclen + 1.
*
* Afterwards, we know that data + data_len is followed by at
* least maclen Bytes, which justifies the call to
* mbedtls_ssl_safer_memcmp() below.
*
* Further, we still know that data_len > minlen */
rec->data_len -= transform->maclen;
ssl_extract_add_data_from_record( add_data, &add_data_len, rec,
transform->minor_ver );
/* Calculate expected MAC. */
MBEDTLS_SSL_DEBUG_BUF( 4, "MAC'd meta-data", add_data,
add_data_len );
mbedtls_md_hmac_update( &transform->md_ctx_dec, add_data,
add_data_len );
mbedtls_md_hmac_update( &transform->md_ctx_dec,
data, rec->data_len );
mbedtls_md_hmac_finish( &transform->md_ctx_dec, mac_expect );
mbedtls_md_hmac_reset( &transform->md_ctx_dec );
MBEDTLS_SSL_DEBUG_BUF( 4, "message mac", data + rec->data_len,
transform->maclen );
MBEDTLS_SSL_DEBUG_BUF( 4, "expected mac", mac_expect,
transform->maclen );
/* Compare expected MAC with MAC at the end of the record. */
if( mbedtls_ssl_safer_memcmp( data + rec->data_len, mac_expect,
transform->maclen ) != 0 )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "message mac does not match" ) );
return( MBEDTLS_ERR_SSL_INVALID_MAC );
}
auth_done++;
}
#endif /* MBEDTLS_SSL_ENCRYPT_THEN_MAC */
/*
* Check length sanity
*/
/* We know from above that data_len > minlen >= 0,
* so the following check in particular implies that
* data_len >= minlen + ivlen ( = minlen or 2 * minlen ). */
if( rec->data_len % transform->ivlen != 0 )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "msglen (%" MBEDTLS_PRINTF_SIZET
") %% ivlen (%" MBEDTLS_PRINTF_SIZET ") != 0",
rec->data_len, transform->ivlen ) );
return( MBEDTLS_ERR_SSL_INVALID_MAC );
}
#if defined(MBEDTLS_SSL_PROTO_TLS1_1) || defined(MBEDTLS_SSL_PROTO_TLS1_2)
/*
* Initialize for prepended IV for block cipher in TLS v1.1 and up
*/
if( transform->minor_ver >= MBEDTLS_SSL_MINOR_VERSION_2 )
{
/* Safe because data_len >= minlen + ivlen = 2 * ivlen. */
memcpy( transform->iv_dec, data, transform->ivlen );
data += transform->ivlen;
rec->data_offset += transform->ivlen;
rec->data_len -= transform->ivlen;
}
#endif /* MBEDTLS_SSL_PROTO_TLS1_1 || MBEDTLS_SSL_PROTO_TLS1_2 */
/* We still have data_len % ivlen == 0 and data_len >= ivlen here. */
if( ( ret = mbedtls_cipher_crypt( &transform->cipher_ctx_dec,
transform->iv_dec, transform->ivlen,
data, rec->data_len, data, &olen ) ) != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_cipher_crypt", ret );
return( ret );
}
/* Double-check that length hasn't changed during decryption. */
if( rec->data_len != olen )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
}
#if defined(MBEDTLS_SSL_PROTO_TLS1)
if( transform->minor_ver < MBEDTLS_SSL_MINOR_VERSION_2 )
{
/*
* Save IV in TLS1, where CBC decryption of consecutive
* records is equivalent to CBC decryption of the concatenation
* of the records; in other words, IVs are maintained across
* record decryptions.
*/
memcpy( transform->iv_dec, transform->cipher_ctx_dec.iv,
transform->ivlen );
}
#endif
/* Safe since data_len >= minlen + maclen + 1, so after having
* subtracted at most minlen and maclen up to this point,
* data_len > 0 (because of data_len % ivlen == 0, it's actually
* >= ivlen ). */
padlen = data[rec->data_len - 1];
if( auth_done == 1 )
{
const size_t mask = mbedtls_ssl_cf_mask_ge(
rec->data_len,
padlen + 1 );
correct &= mask;
padlen &= mask;
}
else
{
#if defined(MBEDTLS_SSL_DEBUG_ALL)
if( rec->data_len < transform->maclen + padlen + 1 )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "msglen (%" MBEDTLS_PRINTF_SIZET
") < maclen (%" MBEDTLS_PRINTF_SIZET
") + padlen (%" MBEDTLS_PRINTF_SIZET ")",
rec->data_len,
transform->maclen,
padlen + 1 ) );
}
#endif
const size_t mask = mbedtls_ssl_cf_mask_ge(
rec->data_len,
transform->maclen + padlen + 1 );
correct &= mask;
padlen &= mask;
}
padlen++;
/* Regardless of the validity of the padding,
* we have data_len >= padlen here. */
#if defined(MBEDTLS_SSL_PROTO_TLS1) || defined(MBEDTLS_SSL_PROTO_TLS1_1) || \
defined(MBEDTLS_SSL_PROTO_TLS1_2)
/* The padding check involves a series of up to 256
* consecutive memory reads at the end of the record
* plaintext buffer. In order to hide the length and
* validity of the padding, always perform exactly
* `min(256,plaintext_len)` reads (but take into account
* only the last `padlen` bytes for the padding check). */
size_t pad_count = 0;
volatile unsigned char* const check = data;
/* Index of first padding byte; it has been ensured above
* that the subtraction is safe. */
size_t const padding_idx = rec->data_len - padlen;
size_t const num_checks = rec->data_len <= 256 ? rec->data_len : 256;
size_t const start_idx = rec->data_len - num_checks;
size_t idx;
for( idx = start_idx; idx < rec->data_len; idx++ )
{
/* pad_count += (idx >= padding_idx) &&
* (check[idx] == padlen - 1);
*/
const size_t mask = mbedtls_ssl_cf_mask_ge( idx, padding_idx );
const size_t equal = mbedtls_ssl_cf_bool_eq( check[idx],
padlen - 1 );
pad_count += mask & equal;
}
correct &= mbedtls_ssl_cf_bool_eq( pad_count, padlen );
#if defined(MBEDTLS_SSL_DEBUG_ALL)
if( padlen > 0 && correct == 0 )
MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad padding byte detected" ) );
#endif
padlen &= mbedtls_ssl_cf_mask_from_bit( correct );
#endif /* MBEDTLS_SSL_PROTO_TLS1 || MBEDTLS_SSL_PROTO_TLS1_1 || \
MBEDTLS_SSL_PROTO_TLS1_2 */
/* If the padding was found to be invalid, padlen == 0
* and the subtraction is safe. If the padding was found valid,
* padlen hasn't been changed and the previous assertion
* data_len >= padlen still holds. */
rec->data_len -= padlen;
}
else
#endif /* MBEDTLS_SSL_SOME_SUITES_USE_CBC */
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
}
#if defined(MBEDTLS_SSL_DEBUG_ALL)
MBEDTLS_SSL_DEBUG_BUF( 4, "raw buffer after decryption",
data, rec->data_len );
#endif
/*
* Authenticate if not done yet.
* Compute the MAC regardless of the padding result (RFC4346, CBCTIME).
*/
#if defined(MBEDTLS_SSL_SOME_MODES_USE_MAC)
if( auth_done == 0 )
{
unsigned char mac_expect[MBEDTLS_SSL_MAC_ADD];
unsigned char mac_peer[MBEDTLS_SSL_MAC_ADD];
/* If the initial value of padlen was such that
* data_len < maclen + padlen + 1, then padlen
* got reset to 1, and the initial check
* data_len >= minlen + maclen + 1
* guarantees that at this point we still
* have at least data_len >= maclen.
*
* If the initial value of padlen was such that
* data_len >= maclen + padlen + 1, then we have
* subtracted either padlen + 1 (if the padding was correct)
* or 0 (if the padding was incorrect) since then,
* hence data_len >= maclen in any case.
*/
rec->data_len -= transform->maclen;
ssl_extract_add_data_from_record( add_data, &add_data_len, rec,
transform->minor_ver );
#if defined(MBEDTLS_SSL_PROTO_TLS1) || defined(MBEDTLS_SSL_PROTO_TLS1_1) || \
defined(MBEDTLS_SSL_PROTO_TLS1_2)
/*
* The next two sizes are the minimum and maximum values of
* data_len over all padlen values.
*
* They're independent of padlen, since we previously did
* data_len -= padlen.
*
* Note that max_len + maclen is never more than the buffer
* length, as we previously did in_msglen -= maclen too.
*/
const size_t max_len = rec->data_len + padlen;
const size_t min_len = ( max_len > 256 ) ? max_len - 256 : 0;
ret = mbedtls_ssl_cf_hmac( &transform->md_ctx_dec,
add_data, add_data_len,
data, rec->data_len, min_len, max_len,
mac_expect );
if( ret != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_cf_hmac", ret );
return( ret );
}
mbedtls_ssl_cf_memcpy_offset( mac_peer, data,
rec->data_len,
min_len, max_len,
transform->maclen );
#endif /* MBEDTLS_SSL_PROTO_TLS1 || MBEDTLS_SSL_PROTO_TLS1_1 || \
MBEDTLS_SSL_PROTO_TLS1_2 */
#if defined(MBEDTLS_SSL_DEBUG_ALL)
MBEDTLS_SSL_DEBUG_BUF( 4, "expected mac", mac_expect, transform->maclen );
MBEDTLS_SSL_DEBUG_BUF( 4, "message mac", mac_peer, transform->maclen );
#endif
if( mbedtls_ssl_safer_memcmp( mac_peer, mac_expect,
transform->maclen ) != 0 )
{
#if defined(MBEDTLS_SSL_DEBUG_ALL)
MBEDTLS_SSL_DEBUG_MSG( 1, ( "message mac does not match" ) );
#endif
correct = 0;
}
auth_done++;
}
/*
* Finally check the correct flag
*/
if( correct == 0 )
return( MBEDTLS_ERR_SSL_INVALID_MAC );
#endif /* MBEDTLS_SSL_SOME_MODES_USE_MAC */
/* Make extra sure authentication was performed, exactly once */
if( auth_done != 1 )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
}
#if defined(MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL)
if( transform->minor_ver == MBEDTLS_SSL_MINOR_VERSION_4 )
{
/* Remove inner padding and infer true content type. */
ret = ssl_parse_inner_plaintext( data, &rec->data_len,
&rec->type );
if( ret != 0 )
return( MBEDTLS_ERR_SSL_INVALID_RECORD );
}
#endif /* MBEDTLS_SSL_PROTO_TLS1_3_EXPERIMENTAL */
#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
if( rec->cid_len != 0 )
{
ret = ssl_parse_inner_plaintext( data, &rec->data_len,
&rec->type );
if( ret != 0 )
return( MBEDTLS_ERR_SSL_INVALID_RECORD );
}
#endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= decrypt buf" ) );
return( 0 );
}
#undef MAC_NONE
#undef MAC_PLAINTEXT
#undef MAC_CIPHERTEXT
/*
* Fill the input message buffer by appending data to it.
* The amount of data already fetched is in ssl->in_left.
*
* If we return 0, is it guaranteed that (at least) nb_want bytes are
* available (from this read and/or a previous one). Otherwise, an error code
* is returned (possibly EOF or WANT_READ).
*
* With stream transport (TLS) on success ssl->in_left == nb_want, but
* with datagram transport (DTLS) on success ssl->in_left >= nb_want,
* since we always read a whole datagram at once.
*
* For DTLS, it is up to the caller to set ssl->next_record_offset when
* they're done reading a record.
*/
int mbedtls_ssl_fetch_input( mbedtls_ssl_context *ssl, size_t nb_want )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
size_t len;
#if defined(MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH)
size_t in_buf_len = ssl->in_buf_len;
#else
size_t in_buf_len = MBEDTLS_SSL_IN_BUFFER_LEN;
#endif
MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> fetch input" ) );
if( ssl->f_recv == NULL && ssl->f_recv_timeout == NULL )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "Bad usage of mbedtls_ssl_set_bio() "
"or mbedtls_ssl_set_bio()" ) );
return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
}
if( nb_want > in_buf_len - (size_t)( ssl->in_hdr - ssl->in_buf ) )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "requesting more data than fits" ) );
return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
}
#if defined(MBEDTLS_SSL_PROTO_DTLS)
if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
{
uint32_t timeout;
/*
* The point is, we need to always read a full datagram at once, so we
* sometimes read more then requested, and handle the additional data.
* It could be the rest of the current record (while fetching the
* header) and/or some other records in the same datagram.
*/
/*
* Move to the next record in the already read datagram if applicable
*/
if( ssl->next_record_offset != 0 )
{
if( ssl->in_left < ssl->next_record_offset )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
}
ssl->in_left -= ssl->next_record_offset;
if( ssl->in_left != 0 )
{
MBEDTLS_SSL_DEBUG_MSG( 2, ( "next record in same datagram, offset: %"
MBEDTLS_PRINTF_SIZET,
ssl->next_record_offset ) );
memmove( ssl->in_hdr,
ssl->in_hdr + ssl->next_record_offset,
ssl->in_left );
}
ssl->next_record_offset = 0;
}
MBEDTLS_SSL_DEBUG_MSG( 2, ( "in_left: %" MBEDTLS_PRINTF_SIZET
", nb_want: %" MBEDTLS_PRINTF_SIZET,
ssl->in_left, nb_want ) );
/*
* Done if we already have enough data.
*/
if( nb_want <= ssl->in_left)
{
MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= fetch input" ) );
return( 0 );
}
/*
* A record can't be split across datagrams. If we need to read but
* are not at the beginning of a new record, the caller did something
* wrong.
*/
if( ssl->in_left != 0 )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
}
/*
* Don't even try to read if time's out already.
* This avoids by-passing the timer when repeatedly receiving messages
* that will end up being dropped.
*/
if( mbedtls_ssl_check_timer( ssl ) != 0 )
{
MBEDTLS_SSL_DEBUG_MSG( 2, ( "timer has expired" ) );
ret = MBEDTLS_ERR_SSL_TIMEOUT;
}
else
{
len = in_buf_len - ( ssl->in_hdr - ssl->in_buf );
if( ssl->state != MBEDTLS_SSL_HANDSHAKE_OVER )
timeout = ssl->handshake->retransmit_timeout;
else
timeout = ssl->conf->read_timeout;
MBEDTLS_SSL_DEBUG_MSG( 3, ( "f_recv_timeout: %lu ms", (unsigned long) timeout ) );
if( ssl->f_recv_timeout != NULL )
ret = ssl->f_recv_timeout( ssl->p_bio, ssl->in_hdr, len,
timeout );
else
ret = ssl->f_recv( ssl->p_bio, ssl->in_hdr, len );
MBEDTLS_SSL_DEBUG_RET( 2, "ssl->f_recv(_timeout)", ret );
if( ret == 0 )
return( MBEDTLS_ERR_SSL_CONN_EOF );
}
if( ret == MBEDTLS_ERR_SSL_TIMEOUT )
{
MBEDTLS_SSL_DEBUG_MSG( 2, ( "timeout" ) );
mbedtls_ssl_set_timer( ssl, 0 );
if( ssl->state != MBEDTLS_SSL_HANDSHAKE_OVER )
{
if( ssl_double_retransmit_timeout( ssl ) != 0 )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "handshake timeout" ) );
return( MBEDTLS_ERR_SSL_TIMEOUT );
}
if( ( ret = mbedtls_ssl_resend( ssl ) ) != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_resend", ret );
return( ret );
}
return( MBEDTLS_ERR_SSL_WANT_READ );
}
#if defined(MBEDTLS_SSL_SRV_C) && defined(MBEDTLS_SSL_RENEGOTIATION)
else if( ssl->conf->endpoint == MBEDTLS_SSL_IS_SERVER &&
ssl->renego_status == MBEDTLS_SSL_RENEGOTIATION_PENDING )
{
if( ( ret = mbedtls_ssl_resend_hello_request( ssl ) ) != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_resend_hello_request",
ret );
return( ret );
}
return( MBEDTLS_ERR_SSL_WANT_READ );
}
#endif /* MBEDTLS_SSL_SRV_C && MBEDTLS_SSL_RENEGOTIATION */
}
if( ret < 0 )
return( ret );
ssl->in_left = ret;
}
else
#endif
{
MBEDTLS_SSL_DEBUG_MSG( 2, ( "in_left: %" MBEDTLS_PRINTF_SIZET
", nb_want: %" MBEDTLS_PRINTF_SIZET,
ssl->in_left, nb_want ) );
while( ssl->in_left < nb_want )
{
len = nb_want - ssl->in_left;
if( mbedtls_ssl_check_timer( ssl ) != 0 )
ret = MBEDTLS_ERR_SSL_TIMEOUT;
else
{
if( ssl->f_recv_timeout != NULL )
{
ret = ssl->f_recv_timeout( ssl->p_bio,
ssl->in_hdr + ssl->in_left, len,
ssl->conf->read_timeout );
}
else
{
ret = ssl->f_recv( ssl->p_bio,
ssl->in_hdr + ssl->in_left, len );
}
}
MBEDTLS_SSL_DEBUG_MSG( 2, ( "in_left: %" MBEDTLS_PRINTF_SIZET
", nb_want: %" MBEDTLS_PRINTF_SIZET,
ssl->in_left, nb_want ) );
MBEDTLS_SSL_DEBUG_RET( 2, "ssl->f_recv(_timeout)", ret );
if( ret == 0 )
return( MBEDTLS_ERR_SSL_CONN_EOF );
if( ret < 0 )
return( ret );
if ( (size_t)ret > len || ( INT_MAX > SIZE_MAX && ret > (int)SIZE_MAX ) )
{
MBEDTLS_SSL_DEBUG_MSG( 1,
( "f_recv returned %d bytes but only %" MBEDTLS_PRINTF_SIZET " were requested",
ret, len ) );
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
}
ssl->in_left += ret;
}
}
MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= fetch input" ) );
return( 0 );
}
/*
* Flush any data not yet written
*/
int mbedtls_ssl_flush_output( mbedtls_ssl_context *ssl )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
unsigned char *buf;
MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> flush output" ) );
if( ssl->f_send == NULL )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "Bad usage of mbedtls_ssl_set_bio() "
"or mbedtls_ssl_set_bio()" ) );
return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
}
/* Avoid incrementing counter if data is flushed */
if( ssl->out_left == 0 )
{
MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= flush output" ) );
return( 0 );
}
while( ssl->out_left > 0 )
{
MBEDTLS_SSL_DEBUG_MSG( 2, ( "message length: %" MBEDTLS_PRINTF_SIZET
", out_left: %" MBEDTLS_PRINTF_SIZET,
mbedtls_ssl_out_hdr_len( ssl ) + ssl->out_msglen, ssl->out_left ) );
buf = ssl->out_hdr - ssl->out_left;
ret = ssl->f_send( ssl->p_bio, buf, ssl->out_left );
MBEDTLS_SSL_DEBUG_RET( 2, "ssl->f_send", ret );
if( ret <= 0 )
return( ret );
if( (size_t)ret > ssl->out_left || ( INT_MAX > SIZE_MAX && ret > (int)SIZE_MAX ) )
{
MBEDTLS_SSL_DEBUG_MSG( 1,
( "f_send returned %d bytes but only %" MBEDTLS_PRINTF_SIZET " bytes were sent",
ret, ssl->out_left ) );
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
}
ssl->out_left -= ret;
}
#if defined(MBEDTLS_SSL_PROTO_DTLS)
if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
{
ssl->out_hdr = ssl->out_buf;
}
else
#endif
{
ssl->out_hdr = ssl->out_buf + 8;
}
mbedtls_ssl_update_out_pointers( ssl, ssl->transform_out );
MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= flush output" ) );
return( 0 );
}
/*
* Functions to handle the DTLS retransmission state machine
*/
#if defined(MBEDTLS_SSL_PROTO_DTLS)
/*
* Append current handshake message to current outgoing flight
*/
static int ssl_flight_append( mbedtls_ssl_context *ssl )
{
mbedtls_ssl_flight_item *msg;
MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> ssl_flight_append" ) );
MBEDTLS_SSL_DEBUG_BUF( 4, "message appended to flight",
ssl->out_msg, ssl->out_msglen );
/* Allocate space for current message */
if( ( msg = mbedtls_calloc( 1, sizeof( mbedtls_ssl_flight_item ) ) ) == NULL )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "alloc %" MBEDTLS_PRINTF_SIZET " bytes failed",
sizeof( mbedtls_ssl_flight_item ) ) );
return( MBEDTLS_ERR_SSL_ALLOC_FAILED );
}
if( ( msg->p = mbedtls_calloc( 1, ssl->out_msglen ) ) == NULL )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "alloc %" MBEDTLS_PRINTF_SIZET " bytes failed",
ssl->out_msglen ) );
mbedtls_free( msg );
return( MBEDTLS_ERR_SSL_ALLOC_FAILED );
}
/* Copy current handshake message with headers */
memcpy( msg->p, ssl->out_msg, ssl->out_msglen );
msg->len = ssl->out_msglen;
msg->type = ssl->out_msgtype;
msg->next = NULL;
/* Append to the current flight */
if( ssl->handshake->flight == NULL )
ssl->handshake->flight = msg;
else
{
mbedtls_ssl_flight_item *cur = ssl->handshake->flight;
while( cur->next != NULL )
cur = cur->next;
cur->next = msg;
}
MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= ssl_flight_append" ) );
return( 0 );
}
/*
* Free the current flight of handshake messages
*/
void mbedtls_ssl_flight_free( mbedtls_ssl_flight_item *flight )
{
mbedtls_ssl_flight_item *cur = flight;
mbedtls_ssl_flight_item *next;
while( cur != NULL )
{
next = cur->next;
mbedtls_free( cur->p );
mbedtls_free( cur );
cur = next;
}
}
/*
* Swap transform_out and out_ctr with the alternative ones
*/
static int ssl_swap_epochs( mbedtls_ssl_context *ssl )
{
mbedtls_ssl_transform *tmp_transform;
unsigned char tmp_out_ctr[8];
if( ssl->transform_out == ssl->handshake->alt_transform_out )
{
MBEDTLS_SSL_DEBUG_MSG( 3, ( "skip swap epochs" ) );
return( 0 );
}
MBEDTLS_SSL_DEBUG_MSG( 3, ( "swap epochs" ) );
/* Swap transforms */
tmp_transform = ssl->transform_out;
ssl->transform_out = ssl->handshake->alt_transform_out;
ssl->handshake->alt_transform_out = tmp_transform;
/* Swap epoch + sequence_number */
memcpy( tmp_out_ctr, ssl->cur_out_ctr, 8 );
memcpy( ssl->cur_out_ctr, ssl->handshake->alt_out_ctr, 8 );
memcpy( ssl->handshake->alt_out_ctr, tmp_out_ctr, 8 );
/* Adjust to the newly activated transform */
mbedtls_ssl_update_out_pointers( ssl, ssl->transform_out );
return( 0 );
}
/*
* Retransmit the current flight of messages.
*/
int mbedtls_ssl_resend( mbedtls_ssl_context *ssl )
{
int ret = 0;
MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> mbedtls_ssl_resend" ) );
ret = mbedtls_ssl_flight_transmit( ssl );
MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= mbedtls_ssl_resend" ) );
return( ret );
}
/*
* Transmit or retransmit the current flight of messages.
*
* Need to remember the current message in case flush_output returns
* WANT_WRITE, causing us to exit this function and come back later.
* This function must be called until state is no longer SENDING.
*/
int mbedtls_ssl_flight_transmit( mbedtls_ssl_context *ssl )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> mbedtls_ssl_flight_transmit" ) );
if( ssl->handshake->retransmit_state != MBEDTLS_SSL_RETRANS_SENDING )
{
MBEDTLS_SSL_DEBUG_MSG( 2, ( "initialise flight transmission" ) );
ssl->handshake->cur_msg = ssl->handshake->flight;
ssl->handshake->cur_msg_p = ssl->handshake->flight->p + 12;
ret = ssl_swap_epochs( ssl );
if( ret != 0 )
return( ret );
ssl->handshake->retransmit_state = MBEDTLS_SSL_RETRANS_SENDING;
}
while( ssl->handshake->cur_msg != NULL )
{
size_t max_frag_len;
const mbedtls_ssl_flight_item * const cur = ssl->handshake->cur_msg;
int const is_finished =
( cur->type == MBEDTLS_SSL_MSG_HANDSHAKE &&
cur->p[0] == MBEDTLS_SSL_HS_FINISHED );
uint8_t const force_flush = ssl->disable_datagram_packing == 1 ?
SSL_FORCE_FLUSH : SSL_DONT_FORCE_FLUSH;
/* Swap epochs before sending Finished: we can't do it after
* sending ChangeCipherSpec, in case write returns WANT_READ.
* Must be done before copying, may change out_msg pointer */
if( is_finished && ssl->handshake->cur_msg_p == ( cur->p + 12 ) )
{
MBEDTLS_SSL_DEBUG_MSG( 2, ( "swap epochs to send finished message" ) );
ret = ssl_swap_epochs( ssl );
if( ret != 0 )
return( ret );
}
ret = ssl_get_remaining_payload_in_datagram( ssl );
if( ret < 0 )
return( ret );
max_frag_len = (size_t) ret;
/* CCS is copied as is, while HS messages may need fragmentation */
if( cur->type == MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC )
{
if( max_frag_len == 0 )
{
if( ( ret = mbedtls_ssl_flush_output( ssl ) ) != 0 )
return( ret );
continue;
}
memcpy( ssl->out_msg, cur->p, cur->len );
ssl->out_msglen = cur->len;
ssl->out_msgtype = cur->type;
/* Update position inside current message */
ssl->handshake->cur_msg_p += cur->len;
}
else
{
const unsigned char * const p = ssl->handshake->cur_msg_p;
const size_t hs_len = cur->len - 12;
const size_t frag_off = p - ( cur->p + 12 );
const size_t rem_len = hs_len - frag_off;
size_t cur_hs_frag_len, max_hs_frag_len;
if( ( max_frag_len < 12 ) || ( max_frag_len == 12 && hs_len != 0 ) )
{
if( is_finished )
{
ret = ssl_swap_epochs( ssl );
if( ret != 0 )
return( ret );
}
if( ( ret = mbedtls_ssl_flush_output( ssl ) ) != 0 )
return( ret );
continue;
}
max_hs_frag_len = max_frag_len - 12;
cur_hs_frag_len = rem_len > max_hs_frag_len ?
max_hs_frag_len : rem_len;
if( frag_off == 0 && cur_hs_frag_len != hs_len )
{
MBEDTLS_SSL_DEBUG_MSG( 2, ( "fragmenting handshake message (%u > %u)",
(unsigned) cur_hs_frag_len,
(unsigned) max_hs_frag_len ) );
}
/* Messages are stored with handshake headers as if not fragmented,
* copy beginning of headers then fill fragmentation fields.
* Handshake headers: type(1) len(3) seq(2) f_off(3) f_len(3) */
memcpy( ssl->out_msg, cur->p, 6 );
ssl->out_msg[6] = ( ( frag_off >> 16 ) & 0xff );
ssl->out_msg[7] = ( ( frag_off >> 8 ) & 0xff );
ssl->out_msg[8] = ( ( frag_off ) & 0xff );
ssl->out_msg[ 9] = ( ( cur_hs_frag_len >> 16 ) & 0xff );
ssl->out_msg[10] = ( ( cur_hs_frag_len >> 8 ) & 0xff );
ssl->out_msg[11] = ( ( cur_hs_frag_len ) & 0xff );
MBEDTLS_SSL_DEBUG_BUF( 3, "handshake header", ssl->out_msg, 12 );
/* Copy the handshake message content and set records fields */
memcpy( ssl->out_msg + 12, p, cur_hs_frag_len );
ssl->out_msglen = cur_hs_frag_len + 12;
ssl->out_msgtype = cur->type;
/* Update position inside current message */
ssl->handshake->cur_msg_p += cur_hs_frag_len;
}
/* If done with the current message move to the next one if any */
if( ssl->handshake->cur_msg_p >= cur->p + cur->len )
{
if( cur->next != NULL )
{
ssl->handshake->cur_msg = cur->next;
ssl->handshake->cur_msg_p = cur->next->p + 12;
}
else
{
ssl->handshake->cur_msg = NULL;
ssl->handshake->cur_msg_p = NULL;
}
}
/* Actually send the message out */
if( ( ret = mbedtls_ssl_write_record( ssl, force_flush ) ) != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_write_record", ret );
return( ret );
}
}
if( ( ret = mbedtls_ssl_flush_output( ssl ) ) != 0 )
return( ret );
/* Update state and set timer */
if( ssl->state == MBEDTLS_SSL_HANDSHAKE_OVER )
ssl->handshake->retransmit_state = MBEDTLS_SSL_RETRANS_FINISHED;
else
{
ssl->handshake->retransmit_state = MBEDTLS_SSL_RETRANS_WAITING;
mbedtls_ssl_set_timer( ssl, ssl->handshake->retransmit_timeout );
}
MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= mbedtls_ssl_flight_transmit" ) );
return( 0 );
}
/*
* To be called when the last message of an incoming flight is received.
*/
void mbedtls_ssl_recv_flight_completed( mbedtls_ssl_context *ssl )
{
/* We won't need to resend that one any more */
mbedtls_ssl_flight_free( ssl->handshake->flight );
ssl->handshake->flight = NULL;
ssl->handshake->cur_msg = NULL;
/* The next incoming flight will start with this msg_seq */
ssl->handshake->in_flight_start_seq = ssl->handshake->in_msg_seq;
/* We don't want to remember CCS's across flight boundaries. */
ssl->handshake->buffering.seen_ccs = 0;
/* Clear future message buffering structure. */
mbedtls_ssl_buffering_free( ssl );
/* Cancel timer */
mbedtls_ssl_set_timer( ssl, 0 );
if( ssl->in_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE &&
ssl->in_msg[0] == MBEDTLS_SSL_HS_FINISHED )
{
ssl->handshake->retransmit_state = MBEDTLS_SSL_RETRANS_FINISHED;
}
else
ssl->handshake->retransmit_state = MBEDTLS_SSL_RETRANS_PREPARING;
}
/*
* To be called when the last message of an outgoing flight is send.
*/
void mbedtls_ssl_send_flight_completed( mbedtls_ssl_context *ssl )
{
ssl_reset_retransmit_timeout( ssl );
mbedtls_ssl_set_timer( ssl, ssl->handshake->retransmit_timeout );
if( ssl->in_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE &&
ssl->in_msg[0] == MBEDTLS_SSL_HS_FINISHED )
{
ssl->handshake->retransmit_state = MBEDTLS_SSL_RETRANS_FINISHED;
}
else
ssl->handshake->retransmit_state = MBEDTLS_SSL_RETRANS_WAITING;
}
#endif /* MBEDTLS_SSL_PROTO_DTLS */
/*
* Handshake layer functions
*/
/*
* Write (DTLS: or queue) current handshake (including CCS) message.
*
* - fill in handshake headers
* - update handshake checksum
* - DTLS: save message for resending
* - then pass to the record layer
*
* DTLS: except for HelloRequest, messages are only queued, and will only be
* actually sent when calling flight_transmit() or resend().
*
* Inputs:
* - ssl->out_msglen: 4 + actual handshake message len
* (4 is the size of handshake headers for TLS)
* - ssl->out_msg[0]: the handshake type (ClientHello, ServerHello, etc)
* - ssl->out_msg + 4: the handshake message body
*
* Outputs, ie state before passing to flight_append() or write_record():
* - ssl->out_msglen: the length of the record contents
* (including handshake headers but excluding record headers)
* - ssl->out_msg: the record contents (handshake headers + content)
*/
int mbedtls_ssl_write_handshake_msg( mbedtls_ssl_context *ssl )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
const size_t hs_len = ssl->out_msglen - 4;
const unsigned char hs_type = ssl->out_msg[0];
MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write handshake message" ) );
/*
* Sanity checks
*/
if( ssl->out_msgtype != MBEDTLS_SSL_MSG_HANDSHAKE &&
ssl->out_msgtype != MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
}
/* Whenever we send anything different from a
* HelloRequest we should be in a handshake - double check. */
if( ! ( ssl->out_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE &&
hs_type == MBEDTLS_SSL_HS_HELLO_REQUEST ) &&
ssl->handshake == NULL )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
}
#if defined(MBEDTLS_SSL_PROTO_DTLS)
if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
ssl->handshake != NULL &&
ssl->handshake->retransmit_state == MBEDTLS_SSL_RETRANS_SENDING )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
}
#endif
/* Double-check that we did not exceed the bounds
* of the outgoing record buffer.
* This should never fail as the various message
* writing functions must obey the bounds of the
* outgoing record buffer, but better be safe.
*
* Note: We deliberately do not check for the MTU or MFL here.
*/
if( ssl->out_msglen > MBEDTLS_SSL_OUT_CONTENT_LEN )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "Record too large: "
"size %" MBEDTLS_PRINTF_SIZET
", maximum %" MBEDTLS_PRINTF_SIZET,
ssl->out_msglen,
(size_t) MBEDTLS_SSL_OUT_CONTENT_LEN ) );
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
}
/*
* Fill handshake headers
*/
if( ssl->out_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE )
{
ssl->out_msg[1] = (unsigned char)( hs_len >> 16 );
ssl->out_msg[2] = (unsigned char)( hs_len >> 8 );
ssl->out_msg[3] = (unsigned char)( hs_len );
/*
* DTLS has additional fields in the Handshake layer,
* between the length field and the actual payload:
* uint16 message_seq;
* uint24 fragment_offset;
* uint24 fragment_length;
*/
#if defined(MBEDTLS_SSL_PROTO_DTLS)
if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
{
/* Make room for the additional DTLS fields */
if( MBEDTLS_SSL_OUT_CONTENT_LEN - ssl->out_msglen < 8 )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "DTLS handshake message too large: "
"size %" MBEDTLS_PRINTF_SIZET ", maximum %" MBEDTLS_PRINTF_SIZET,
hs_len,
(size_t) ( MBEDTLS_SSL_OUT_CONTENT_LEN - 12 ) ) );
return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
}
memmove( ssl->out_msg + 12, ssl->out_msg + 4, hs_len );
ssl->out_msglen += 8;
/* Write message_seq and update it, except for HelloRequest */
if( hs_type != MBEDTLS_SSL_HS_HELLO_REQUEST )
{
ssl->out_msg[4] = ( ssl->handshake->out_msg_seq >> 8 ) & 0xFF;
ssl->out_msg[5] = ( ssl->handshake->out_msg_seq ) & 0xFF;
++( ssl->handshake->out_msg_seq );
}
else
{
ssl->out_msg[4] = 0;
ssl->out_msg[5] = 0;
}
/* Handshake hashes are computed without fragmentation,
* so set frag_offset = 0 and frag_len = hs_len for now */
memset( ssl->out_msg + 6, 0x00, 3 );
memcpy( ssl->out_msg + 9, ssl->out_msg + 1, 3 );
}
#endif /* MBEDTLS_SSL_PROTO_DTLS */
/* Update running hashes of handshake messages seen */
if( hs_type != MBEDTLS_SSL_HS_HELLO_REQUEST )
ssl->handshake->update_checksum( ssl, ssl->out_msg, ssl->out_msglen );
}
/* Either send now, or just save to be sent (and resent) later */
#if defined(MBEDTLS_SSL_PROTO_DTLS)
if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
! ( ssl->out_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE &&
hs_type == MBEDTLS_SSL_HS_HELLO_REQUEST ) )
{
if( ( ret = ssl_flight_append( ssl ) ) != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "ssl_flight_append", ret );
return( ret );
}
}
else
#endif
{
if( ( ret = mbedtls_ssl_write_record( ssl, SSL_FORCE_FLUSH ) ) != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "ssl_write_record", ret );
return( ret );
}
}
MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= write handshake message" ) );
return( 0 );
}
/*
* Record layer functions
*/
/*
* Write current record.
*
* Uses:
* - ssl->out_msgtype: type of the message (AppData, Handshake, Alert, CCS)
* - ssl->out_msglen: length of the record content (excl headers)
* - ssl->out_msg: record content
*/
int mbedtls_ssl_write_record( mbedtls_ssl_context *ssl, uint8_t force_flush )
{
int ret, done = 0;
size_t len = ssl->out_msglen;
uint8_t flush = force_flush;
MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write record" ) );
if( !done )
{
unsigned i;
size_t protected_record_size;
#if defined(MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH)
size_t out_buf_len = ssl->out_buf_len;
#else
size_t out_buf_len = MBEDTLS_SSL_OUT_BUFFER_LEN;
#endif
/* Skip writing the record content type to after the encryption,
* as it may change when using the CID extension. */
mbedtls_ssl_write_version( ssl->major_ver, ssl->minor_ver,
ssl->conf->transport, ssl->out_hdr + 1 );
memcpy( ssl->out_ctr, ssl->cur_out_ctr, 8 );
ssl->out_len[0] = (unsigned char)( len >> 8 );
ssl->out_len[1] = (unsigned char)( len );
if( ssl->transform_out != NULL )
{
mbedtls_record rec;
rec.buf = ssl->out_iv;
rec.buf_len = out_buf_len - ( ssl->out_iv - ssl->out_buf );
rec.data_len = ssl->out_msglen;
rec.data_offset = ssl->out_msg - rec.buf;
memcpy( &rec.ctr[0], ssl->out_ctr, 8 );
mbedtls_ssl_write_version( ssl->major_ver, ssl->minor_ver,
ssl->conf->transport, rec.ver );
rec.type = ssl->out_msgtype;
#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
/* The CID is set by mbedtls_ssl_encrypt_buf(). */
rec.cid_len = 0;
#endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
if( ( ret = mbedtls_ssl_encrypt_buf( ssl, ssl->transform_out, &rec,
ssl->conf->f_rng, ssl->conf->p_rng ) ) != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "ssl_encrypt_buf", ret );
return( ret );
}
if( rec.data_offset != 0 )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
}
/* Update the record content type and CID. */
ssl->out_msgtype = rec.type;
#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID )
memcpy( ssl->out_cid, rec.cid, rec.cid_len );
#endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
ssl->out_msglen = len = rec.data_len;
ssl->out_len[0] = (unsigned char)( rec.data_len >> 8 );
ssl->out_len[1] = (unsigned char)( rec.data_len );
}
protected_record_size = len + mbedtls_ssl_out_hdr_len( ssl );
#if defined(MBEDTLS_SSL_PROTO_DTLS)
/* In case of DTLS, double-check that we don't exceed
* the remaining space in the datagram. */
if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
{
ret = ssl_get_remaining_space_in_datagram( ssl );
if( ret < 0 )
return( ret );
if( protected_record_size > (size_t) ret )
{
/* Should never happen */
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
}
}
#endif /* MBEDTLS_SSL_PROTO_DTLS */
/* Now write the potentially updated record content type. */
ssl->out_hdr[0] = (unsigned char) ssl->out_msgtype;
MBEDTLS_SSL_DEBUG_MSG( 3, ( "output record: msgtype = %u, "
"version = [%u:%u], msglen = %" MBEDTLS_PRINTF_SIZET,
ssl->out_hdr[0], ssl->out_hdr[1],
ssl->out_hdr[2], len ) );
MBEDTLS_SSL_DEBUG_BUF( 4, "output record sent to network",
ssl->out_hdr, protected_record_size );
ssl->out_left += protected_record_size;
ssl->out_hdr += protected_record_size;
mbedtls_ssl_update_out_pointers( ssl, ssl->transform_out );
for( i = 8; i > mbedtls_ssl_ep_len( ssl ); i-- )
if( ++ssl->cur_out_ctr[i - 1] != 0 )
break;
/* The loop goes to its end iff the counter is wrapping */
if( i == mbedtls_ssl_ep_len( ssl ) )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "outgoing message counter would wrap" ) );
return( MBEDTLS_ERR_SSL_COUNTER_WRAPPING );
}
}
#if defined(MBEDTLS_SSL_PROTO_DTLS)
if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
flush == SSL_DONT_FORCE_FLUSH )
{
size_t remaining;
ret = ssl_get_remaining_payload_in_datagram( ssl );
if( ret < 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "ssl_get_remaining_payload_in_datagram",
ret );
return( ret );
}
remaining = (size_t) ret;
if( remaining == 0 )
{
flush = SSL_FORCE_FLUSH;
}
else
{
MBEDTLS_SSL_DEBUG_MSG( 2, ( "Still %u bytes available in current datagram", (unsigned) remaining ) );
}
}
#endif /* MBEDTLS_SSL_PROTO_DTLS */
if( ( flush == SSL_FORCE_FLUSH ) &&
( ret = mbedtls_ssl_flush_output( ssl ) ) != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_flush_output", ret );
return( ret );
}
MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= write record" ) );
return( 0 );
}
#if defined(MBEDTLS_SSL_PROTO_DTLS)
static int ssl_hs_is_proper_fragment( mbedtls_ssl_context *ssl )
{
if( ssl->in_msglen < ssl->in_hslen ||
memcmp( ssl->in_msg + 6, "\0\0\0", 3 ) != 0 ||
memcmp( ssl->in_msg + 9, ssl->in_msg + 1, 3 ) != 0 )
{
return( 1 );
}
return( 0 );
}
static uint32_t ssl_get_hs_frag_len( mbedtls_ssl_context const *ssl )
{
return( ( ssl->in_msg[9] << 16 ) |
( ssl->in_msg[10] << 8 ) |
ssl->in_msg[11] );
}
static uint32_t ssl_get_hs_frag_off( mbedtls_ssl_context const *ssl )
{
return( ( ssl->in_msg[6] << 16 ) |
( ssl->in_msg[7] << 8 ) |
ssl->in_msg[8] );
}
static int ssl_check_hs_header( mbedtls_ssl_context const *ssl )
{
uint32_t msg_len, frag_off, frag_len;
msg_len = ssl_get_hs_total_len( ssl );
frag_off = ssl_get_hs_frag_off( ssl );
frag_len = ssl_get_hs_frag_len( ssl );
if( frag_off > msg_len )
return( -1 );
if( frag_len > msg_len - frag_off )
return( -1 );
if( frag_len + 12 > ssl->in_msglen )
return( -1 );
return( 0 );
}
/*
* Mark bits in bitmask (used for DTLS HS reassembly)
*/
static void ssl_bitmask_set( unsigned char *mask, size_t offset, size_t len )
{
unsigned int start_bits, end_bits;
start_bits = 8 - ( offset % 8 );
if( start_bits != 8 )
{
size_t first_byte_idx = offset / 8;
/* Special case */
if( len <= start_bits )
{
for( ; len != 0; len-- )
mask[first_byte_idx] |= 1 << ( start_bits - len );
/* Avoid potential issues with offset or len becoming invalid */
return;
}
offset += start_bits; /* Now offset % 8 == 0 */
len -= start_bits;
for( ; start_bits != 0; start_bits-- )
mask[first_byte_idx] |= 1 << ( start_bits - 1 );
}
end_bits = len % 8;
if( end_bits != 0 )
{
size_t last_byte_idx = ( offset + len ) / 8;
len -= end_bits; /* Now len % 8 == 0 */
for( ; end_bits != 0; end_bits-- )
mask[last_byte_idx] |= 1 << ( 8 - end_bits );
}
memset( mask + offset / 8, 0xFF, len / 8 );
}
/*
* Check that bitmask is full
*/
static int ssl_bitmask_check( unsigned char *mask, size_t len )
{
size_t i;
for( i = 0; i < len / 8; i++ )
if( mask[i] != 0xFF )
return( -1 );
for( i = 0; i < len % 8; i++ )
if( ( mask[len / 8] & ( 1 << ( 7 - i ) ) ) == 0 )
return( -1 );
return( 0 );
}
/* msg_len does not include the handshake header */
static size_t ssl_get_reassembly_buffer_size( size_t msg_len,
unsigned add_bitmap )
{
size_t alloc_len;
alloc_len = 12; /* Handshake header */
alloc_len += msg_len; /* Content buffer */
if( add_bitmap )
alloc_len += msg_len / 8 + ( msg_len % 8 != 0 ); /* Bitmap */
return( alloc_len );
}
#endif /* MBEDTLS_SSL_PROTO_DTLS */
static uint32_t ssl_get_hs_total_len( mbedtls_ssl_context const *ssl )
{
return( ( ssl->in_msg[1] << 16 ) |
( ssl->in_msg[2] << 8 ) |
ssl->in_msg[3] );
}
int mbedtls_ssl_prepare_handshake_record( mbedtls_ssl_context *ssl )
{
if( ssl->in_msglen < mbedtls_ssl_hs_hdr_len( ssl ) )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "handshake message too short: %" MBEDTLS_PRINTF_SIZET,
ssl->in_msglen ) );
return( MBEDTLS_ERR_SSL_INVALID_RECORD );
}
ssl->in_hslen = mbedtls_ssl_hs_hdr_len( ssl ) + ssl_get_hs_total_len( ssl );
MBEDTLS_SSL_DEBUG_MSG( 3, ( "handshake message: msglen ="
" %" MBEDTLS_PRINTF_SIZET ", type = %u, hslen = %" MBEDTLS_PRINTF_SIZET,
ssl->in_msglen, ssl->in_msg[0], ssl->in_hslen ) );
#if defined(MBEDTLS_SSL_PROTO_DTLS)
if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
unsigned int recv_msg_seq = ( ssl->in_msg[4] << 8 ) | ssl->in_msg[5];
if( ssl_check_hs_header( ssl ) != 0 )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "invalid handshake header" ) );
return( MBEDTLS_ERR_SSL_INVALID_RECORD );
}
if( ssl->handshake != NULL &&
( ( ssl->state != MBEDTLS_SSL_HANDSHAKE_OVER &&
recv_msg_seq != ssl->handshake->in_msg_seq ) ||
( ssl->state == MBEDTLS_SSL_HANDSHAKE_OVER &&
ssl->in_msg[0] != MBEDTLS_SSL_HS_CLIENT_HELLO ) ) )
{
if( recv_msg_seq > ssl->handshake->in_msg_seq )
{
MBEDTLS_SSL_DEBUG_MSG( 2, ( "received future handshake message of sequence number %u (next %u)",
recv_msg_seq,
ssl->handshake->in_msg_seq ) );
return( MBEDTLS_ERR_SSL_EARLY_MESSAGE );
}
/* Retransmit only on last message from previous flight, to avoid
* too many retransmissions.
* Besides, No sane server ever retransmits HelloVerifyRequest */
if( recv_msg_seq == ssl->handshake->in_flight_start_seq - 1 &&
ssl->in_msg[0] != MBEDTLS_SSL_HS_HELLO_VERIFY_REQUEST )
{
MBEDTLS_SSL_DEBUG_MSG( 2, ( "received message from last flight, "
"message_seq = %u, start_of_flight = %u",
recv_msg_seq,
ssl->handshake->in_flight_start_seq ) );
if( ( ret = mbedtls_ssl_resend( ssl ) ) != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_resend", ret );
return( ret );
}
}
else
{
MBEDTLS_SSL_DEBUG_MSG( 2, ( "dropping out-of-sequence message: "
"message_seq = %u, expected = %u",
recv_msg_seq,
ssl->handshake->in_msg_seq ) );
}
return( MBEDTLS_ERR_SSL_CONTINUE_PROCESSING );
}
/* Wait until message completion to increment in_msg_seq */
/* Message reassembly is handled alongside buffering of future
* messages; the commonality is that both handshake fragments and
* future messages cannot be forwarded immediately to the
* handshake logic layer. */
if( ssl_hs_is_proper_fragment( ssl ) == 1 )
{
MBEDTLS_SSL_DEBUG_MSG( 2, ( "found fragmented DTLS handshake message" ) );
return( MBEDTLS_ERR_SSL_EARLY_MESSAGE );
}
}
else
#endif /* MBEDTLS_SSL_PROTO_DTLS */
/* With TLS we don't handle fragmentation (for now) */
if( ssl->in_msglen < ssl->in_hslen )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "TLS handshake fragmentation not supported" ) );
return( MBEDTLS_ERR_SSL_FEATURE_UNAVAILABLE );
}
return( 0 );
}
void mbedtls_ssl_update_handshake_status( mbedtls_ssl_context *ssl )
{
mbedtls_ssl_handshake_params * const hs = ssl->handshake;
if( ssl->state != MBEDTLS_SSL_HANDSHAKE_OVER && hs != NULL )
{
ssl->handshake->update_checksum( ssl, ssl->in_msg, ssl->in_hslen );
}
/* Handshake message is complete, increment counter */
#if defined(MBEDTLS_SSL_PROTO_DTLS)
if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
ssl->handshake != NULL )
{
unsigned offset;
mbedtls_ssl_hs_buffer *hs_buf;
/* Increment handshake sequence number */
hs->in_msg_seq++;
/*
* Clear up handshake buffering and reassembly structure.
*/
/* Free first entry */
ssl_buffering_free_slot( ssl, 0 );
/* Shift all other entries */
for( offset = 0, hs_buf = &hs->buffering.hs[0];
offset + 1 < MBEDTLS_SSL_MAX_BUFFERED_HS;
offset++, hs_buf++ )
{
*hs_buf = *(hs_buf + 1);
}
/* Create a fresh last entry */
memset( hs_buf, 0, sizeof( mbedtls_ssl_hs_buffer ) );
}
#endif
}
/*
* DTLS anti-replay: RFC 6347 4.1.2.6
*
* in_window is a field of bits numbered from 0 (lsb) to 63 (msb).
* Bit n is set iff record number in_window_top - n has been seen.
*
* Usually, in_window_top is the last record number seen and the lsb of
* in_window is set. The only exception is the initial state (record number 0
* not seen yet).
*/
#if defined(MBEDTLS_SSL_DTLS_ANTI_REPLAY)
void mbedtls_ssl_dtls_replay_reset( mbedtls_ssl_context *ssl )
{
ssl->in_window_top = 0;
ssl->in_window = 0;
}
static inline uint64_t ssl_load_six_bytes( unsigned char *buf )
{
return( ( (uint64_t) buf[0] << 40 ) |
( (uint64_t) buf[1] << 32 ) |
( (uint64_t) buf[2] << 24 ) |
( (uint64_t) buf[3] << 16 ) |
( (uint64_t) buf[4] << 8 ) |
( (uint64_t) buf[5] ) );
}
static int mbedtls_ssl_dtls_record_replay_check( mbedtls_ssl_context *ssl, uint8_t *record_in_ctr )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
unsigned char *original_in_ctr;
// save original in_ctr
original_in_ctr = ssl->in_ctr;
// use counter from record
ssl->in_ctr = record_in_ctr;
ret = mbedtls_ssl_dtls_replay_check( (mbedtls_ssl_context const *) ssl );
// restore the counter
ssl->in_ctr = original_in_ctr;
return ret;
}
/*
* Return 0 if sequence number is acceptable, -1 otherwise
*/
int mbedtls_ssl_dtls_replay_check( mbedtls_ssl_context const *ssl )
{
uint64_t rec_seqnum = ssl_load_six_bytes( ssl->in_ctr + 2 );
uint64_t bit;
if( ssl->conf->anti_replay == MBEDTLS_SSL_ANTI_REPLAY_DISABLED )
return( 0 );
if( rec_seqnum > ssl->in_window_top )
return( 0 );
bit = ssl->in_window_top - rec_seqnum;
if( bit >= 64 )
return( -1 );
if( ( ssl->in_window & ( (uint64_t) 1 << bit ) ) != 0 )
return( -1 );
return( 0 );
}
/*
* Update replay window on new validated record
*/
void mbedtls_ssl_dtls_replay_update( mbedtls_ssl_context *ssl )
{
uint64_t rec_seqnum = ssl_load_six_bytes( ssl->in_ctr + 2 );
if( ssl->conf->anti_replay == MBEDTLS_SSL_ANTI_REPLAY_DISABLED )
return;
if( rec_seqnum > ssl->in_window_top )
{
/* Update window_top and the contents of the window */
uint64_t shift = rec_seqnum - ssl->in_window_top;
if( shift >= 64 )
ssl->in_window = 1;
else
{
ssl->in_window <<= shift;
ssl->in_window |= 1;
}
ssl->in_window_top = rec_seqnum;
}
else
{
/* Mark that number as seen in the current window */
uint64_t bit = ssl->in_window_top - rec_seqnum;
if( bit < 64 ) /* Always true, but be extra sure */
ssl->in_window |= (uint64_t) 1 << bit;
}
}
#endif /* MBEDTLS_SSL_DTLS_ANTI_REPLAY */
#if defined(MBEDTLS_SSL_DTLS_CLIENT_PORT_REUSE) && defined(MBEDTLS_SSL_SRV_C)
/*
* Without any SSL context, check if a datagram looks like a ClientHello with
* a valid cookie, and if it doesn't, generate a HelloVerifyRequest message.
* Both input and output include full DTLS headers.
*
* - if cookie is valid, return 0
* - if ClientHello looks superficially valid but cookie is not,
* fill obuf and set olen, then
* return MBEDTLS_ERR_SSL_HELLO_VERIFY_REQUIRED
* - otherwise return a specific error code
*/
static int ssl_check_dtls_clihlo_cookie(
mbedtls_ssl_cookie_write_t *f_cookie_write,
mbedtls_ssl_cookie_check_t *f_cookie_check,
void *p_cookie,
const unsigned char *cli_id, size_t cli_id_len,
const unsigned char *in, size_t in_len,
unsigned char *obuf, size_t buf_len, size_t *olen )
{
size_t sid_len, cookie_len;
unsigned char *p;
/*
* Structure of ClientHello with record and handshake headers,
* and expected values. We don't need to check a lot, more checks will be
* done when actually parsing the ClientHello - skipping those checks
* avoids code duplication and does not make cookie forging any easier.
*
* 0-0 ContentType type; copied, must be handshake
* 1-2 ProtocolVersion version; copied
* 3-4 uint16 epoch; copied, must be 0
* 5-10 uint48 sequence_number; copied
* 11-12 uint16 length; (ignored)
*
* 13-13 HandshakeType msg_type; (ignored)
* 14-16 uint24 length; (ignored)
* 17-18 uint16 message_seq; copied
* 19-21 uint24 fragment_offset; copied, must be 0
* 22-24 uint24 fragment_length; (ignored)
*
* 25-26 ProtocolVersion client_version; (ignored)
* 27-58 Random random; (ignored)
* 59-xx SessionID session_id; 1 byte len + sid_len content
* 60+ opaque cookie<0..2^8-1>; 1 byte len + content
* ...
*
* Minimum length is 61 bytes.
*/
if( in_len < 61 ||
in[0] != MBEDTLS_SSL_MSG_HANDSHAKE ||
in[3] != 0 || in[4] != 0 ||
in[19] != 0 || in[20] != 0 || in[21] != 0 )
{
return( MBEDTLS_ERR_SSL_BAD_HS_CLIENT_HELLO );
}
sid_len = in[59];
if( sid_len > in_len - 61 )
return( MBEDTLS_ERR_SSL_BAD_HS_CLIENT_HELLO );
cookie_len = in[60 + sid_len];
if( cookie_len > in_len - 60 )
return( MBEDTLS_ERR_SSL_BAD_HS_CLIENT_HELLO );
if( f_cookie_check( p_cookie, in + sid_len + 61, cookie_len,
cli_id, cli_id_len ) == 0 )
{
/* Valid cookie */
return( 0 );
}
/*
* If we get here, we've got an invalid cookie, let's prepare HVR.
*
* 0-0 ContentType type; copied
* 1-2 ProtocolVersion version; copied
* 3-4 uint16 epoch; copied
* 5-10 uint48 sequence_number; copied
* 11-12 uint16 length; olen - 13
*
* 13-13 HandshakeType msg_type; hello_verify_request
* 14-16 uint24 length; olen - 25
* 17-18 uint16 message_seq; copied
* 19-21 uint24 fragment_offset; copied
* 22-24 uint24 fragment_length; olen - 25
*
* 25-26 ProtocolVersion server_version; 0xfe 0xff
* 27-27 opaque cookie<0..2^8-1>; cookie_len = olen - 27, cookie
*
* Minimum length is 28.
*/
if( buf_len < 28 )
return( MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL );
/* Copy most fields and adapt others */
memcpy( obuf, in, 25 );
obuf[13] = MBEDTLS_SSL_HS_HELLO_VERIFY_REQUEST;
obuf[25] = 0xfe;
obuf[26] = 0xff;
/* Generate and write actual cookie */
p = obuf + 28;
if( f_cookie_write( p_cookie,
&p, obuf + buf_len, cli_id, cli_id_len ) != 0 )
{
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
}
*olen = p - obuf;
/* Go back and fill length fields */
obuf[27] = (unsigned char)( *olen - 28 );
obuf[14] = obuf[22] = (unsigned char)( ( *olen - 25 ) >> 16 );
obuf[15] = obuf[23] = (unsigned char)( ( *olen - 25 ) >> 8 );
obuf[16] = obuf[24] = (unsigned char)( ( *olen - 25 ) );
obuf[11] = (unsigned char)( ( *olen - 13 ) >> 8 );
obuf[12] = (unsigned char)( ( *olen - 13 ) );
return( MBEDTLS_ERR_SSL_HELLO_VERIFY_REQUIRED );
}
/*
* Handle possible client reconnect with the same UDP quadruplet
* (RFC 6347 Section 4.2.8).
*
* Called by ssl_parse_record_header() in case we receive an epoch 0 record
* that looks like a ClientHello.
*
* - if the input looks like a ClientHello without cookies,
* send back HelloVerifyRequest, then return 0
* - if the input looks like a ClientHello with a valid cookie,
* reset the session of the current context, and
* return MBEDTLS_ERR_SSL_CLIENT_RECONNECT
* - if anything goes wrong, return a specific error code
*
* This function is called (through ssl_check_client_reconnect()) when an
* unexpected record is found in ssl_get_next_record(), which will discard the
* record if we return 0, and bubble up the return value otherwise (this
* includes the case of MBEDTLS_ERR_SSL_CLIENT_RECONNECT and of unexpected
* errors, and is the right thing to do in both cases).
*/
static int ssl_handle_possible_reconnect( mbedtls_ssl_context *ssl )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
size_t len;
if( ssl->conf->f_cookie_write == NULL ||
ssl->conf->f_cookie_check == NULL )
{
/* If we can't use cookies to verify reachability of the peer,
* drop the record. */
MBEDTLS_SSL_DEBUG_MSG( 1, ( "no cookie callbacks, "
"can't check reconnect validity" ) );
return( 0 );
}
ret = ssl_check_dtls_clihlo_cookie(
ssl->conf->f_cookie_write,
ssl->conf->f_cookie_check,
ssl->conf->p_cookie,
ssl->cli_id, ssl->cli_id_len,
ssl->in_buf, ssl->in_left,
ssl->out_buf, MBEDTLS_SSL_OUT_CONTENT_LEN, &len );
MBEDTLS_SSL_DEBUG_RET( 2, "ssl_check_dtls_clihlo_cookie", ret );
if( ret == MBEDTLS_ERR_SSL_HELLO_VERIFY_REQUIRED )
{
int send_ret;
MBEDTLS_SSL_DEBUG_MSG( 1, ( "sending HelloVerifyRequest" ) );
MBEDTLS_SSL_DEBUG_BUF( 4, "output record sent to network",
ssl->out_buf, len );
/* Don't check write errors as we can't do anything here.
* If the error is permanent we'll catch it later,
* if it's not, then hopefully it'll work next time. */
send_ret = ssl->f_send( ssl->p_bio, ssl->out_buf, len );
MBEDTLS_SSL_DEBUG_RET( 2, "ssl->f_send", send_ret );
(void) send_ret;
return( 0 );
}
if( ret == 0 )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "cookie is valid, resetting context" ) );
if( ( ret = mbedtls_ssl_session_reset_int( ssl, 1 ) ) != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "reset", ret );
return( ret );
}
return( MBEDTLS_ERR_SSL_CLIENT_RECONNECT );
}
return( ret );
}
#endif /* MBEDTLS_SSL_DTLS_CLIENT_PORT_REUSE && MBEDTLS_SSL_SRV_C */
static int ssl_check_record_type( uint8_t record_type )
{
if( record_type != MBEDTLS_SSL_MSG_HANDSHAKE &&
record_type != MBEDTLS_SSL_MSG_ALERT &&
record_type != MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC &&
record_type != MBEDTLS_SSL_MSG_APPLICATION_DATA )
{
return( MBEDTLS_ERR_SSL_INVALID_RECORD );
}
return( 0 );
}
/*
* ContentType type;
* ProtocolVersion version;
* uint16 epoch; // DTLS only
* uint48 sequence_number; // DTLS only
* uint16 length;
*
* Return 0 if header looks sane (and, for DTLS, the record is expected)
* MBEDTLS_ERR_SSL_INVALID_RECORD if the header looks bad,
* MBEDTLS_ERR_SSL_UNEXPECTED_RECORD (DTLS only) if sane but unexpected.
*
* With DTLS, mbedtls_ssl_read_record() will:
* 1. proceed with the record if this function returns 0
* 2. drop only the current record if this function returns UNEXPECTED_RECORD
* 3. return CLIENT_RECONNECT if this function return that value
* 4. drop the whole datagram if this function returns anything else.
* Point 2 is needed when the peer is resending, and we have already received
* the first record from a datagram but are still waiting for the others.
*/
static int ssl_parse_record_header( mbedtls_ssl_context const *ssl,
unsigned char *buf,
size_t len,
mbedtls_record *rec )
{
int major_ver, minor_ver;
size_t const rec_hdr_type_offset = 0;
size_t const rec_hdr_type_len = 1;
size_t const rec_hdr_version_offset = rec_hdr_type_offset +
rec_hdr_type_len;
size_t const rec_hdr_version_len = 2;
size_t const rec_hdr_ctr_len = 8;
#if defined(MBEDTLS_SSL_PROTO_DTLS)
uint32_t rec_epoch;
size_t const rec_hdr_ctr_offset = rec_hdr_version_offset +
rec_hdr_version_len;
#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
size_t const rec_hdr_cid_offset = rec_hdr_ctr_offset +
rec_hdr_ctr_len;
size_t rec_hdr_cid_len = 0;
#endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
#endif /* MBEDTLS_SSL_PROTO_DTLS */
size_t rec_hdr_len_offset; /* To be determined */
size_t const rec_hdr_len_len = 2;
/*
* Check minimum lengths for record header.
*/
#if defined(MBEDTLS_SSL_PROTO_DTLS)
if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
{
rec_hdr_len_offset = rec_hdr_ctr_offset + rec_hdr_ctr_len;
}
else
#endif /* MBEDTLS_SSL_PROTO_DTLS */
{
rec_hdr_len_offset = rec_hdr_version_offset + rec_hdr_version_len;
}
if( len < rec_hdr_len_offset + rec_hdr_len_len )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "datagram of length %u too small to hold DTLS record header of length %u",
(unsigned) len,
(unsigned)( rec_hdr_len_len + rec_hdr_len_len ) ) );
return( MBEDTLS_ERR_SSL_INVALID_RECORD );
}
/*
* Parse and validate record content type
*/
rec->type = buf[ rec_hdr_type_offset ];
/* Check record content type */
#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
rec->cid_len = 0;
if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
ssl->conf->cid_len != 0 &&
rec->type == MBEDTLS_SSL_MSG_CID )
{
/* Shift pointers to account for record header including CID
* struct {
* ContentType special_type = tls12_cid;
* ProtocolVersion version;
* uint16 epoch;
* uint48 sequence_number;
* opaque cid[cid_length]; // Additional field compared to
* // default DTLS record format
* uint16 length;
* opaque enc_content[DTLSCiphertext.length];
* } DTLSCiphertext;
*/
/* So far, we only support static CID lengths
* fixed in the configuration. */
rec_hdr_cid_len = ssl->conf->cid_len;
rec_hdr_len_offset += rec_hdr_cid_len;
if( len < rec_hdr_len_offset + rec_hdr_len_len )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "datagram of length %u too small to hold DTLS record header including CID, length %u",
(unsigned) len,
(unsigned)( rec_hdr_len_offset + rec_hdr_len_len ) ) );
return( MBEDTLS_ERR_SSL_INVALID_RECORD );
}
/* configured CID len is guaranteed at most 255, see
* MBEDTLS_SSL_CID_OUT_LEN_MAX in check_config.h */
rec->cid_len = (uint8_t) rec_hdr_cid_len;
memcpy( rec->cid, buf + rec_hdr_cid_offset, rec_hdr_cid_len );
}
else
#endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
{
if( ssl_check_record_type( rec->type ) )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "unknown record type %u",
(unsigned) rec->type ) );
return( MBEDTLS_ERR_SSL_INVALID_RECORD );
}
}
/*
* Parse and validate record version
*/
rec->ver[0] = buf[ rec_hdr_version_offset + 0 ];
rec->ver[1] = buf[ rec_hdr_version_offset + 1 ];
mbedtls_ssl_read_version( &major_ver, &minor_ver,
ssl->conf->transport,
&rec->ver[0] );
if( major_ver != ssl->major_ver )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "major version mismatch" ) );
return( MBEDTLS_ERR_SSL_INVALID_RECORD );
}
if( minor_ver > ssl->conf->max_minor_ver )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "minor version mismatch" ) );
return( MBEDTLS_ERR_SSL_INVALID_RECORD );
}
/*
* Parse/Copy record sequence number.
*/
#if defined(MBEDTLS_SSL_PROTO_DTLS)
if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
{
/* Copy explicit record sequence number from input buffer. */
memcpy( &rec->ctr[0], buf + rec_hdr_ctr_offset,
rec_hdr_ctr_len );
}
else
#endif /* MBEDTLS_SSL_PROTO_DTLS */
{
/* Copy implicit record sequence number from SSL context structure. */
memcpy( &rec->ctr[0], ssl->in_ctr, rec_hdr_ctr_len );
}
/*
* Parse record length.
*/
rec->data_offset = rec_hdr_len_offset + rec_hdr_len_len;
rec->data_len = ( (size_t) buf[ rec_hdr_len_offset + 0 ] << 8 ) |
( (size_t) buf[ rec_hdr_len_offset + 1 ] << 0 );
MBEDTLS_SSL_DEBUG_BUF( 4, "input record header", buf, rec->data_offset );
MBEDTLS_SSL_DEBUG_MSG( 3, ( "input record: msgtype = %u, "
"version = [%d:%d], msglen = %" MBEDTLS_PRINTF_SIZET,
rec->type,
major_ver, minor_ver, rec->data_len ) );
rec->buf = buf;
rec->buf_len = rec->data_offset + rec->data_len;
if( rec->data_len == 0 )
return( MBEDTLS_ERR_SSL_INVALID_RECORD );
/*
* DTLS-related tests.
* Check epoch before checking length constraint because
* the latter varies with the epoch. E.g., if a ChangeCipherSpec
* message gets duplicated before the corresponding Finished message,
* the second ChangeCipherSpec should be discarded because it belongs
* to an old epoch, but not because its length is shorter than
* the minimum record length for packets using the new record transform.
* Note that these two kinds of failures are handled differently,
* as an unexpected record is silently skipped but an invalid
* record leads to the entire datagram being dropped.
*/
#if defined(MBEDTLS_SSL_PROTO_DTLS)
if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
{
rec_epoch = ( rec->ctr[0] << 8 ) | rec->ctr[1];
/* Check that the datagram is large enough to contain a record
* of the advertised length. */
if( len < rec->data_offset + rec->data_len )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "Datagram of length %u too small to contain record of advertised length %u.",
(unsigned) len,
(unsigned)( rec->data_offset + rec->data_len ) ) );
return( MBEDTLS_ERR_SSL_INVALID_RECORD );
}
/* Records from other, non-matching epochs are silently discarded.
* (The case of same-port Client reconnects must be considered in
* the caller). */
if( rec_epoch != ssl->in_epoch )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "record from another epoch: "
"expected %u, received %lu",
ssl->in_epoch, (unsigned long) rec_epoch ) );
/* Records from the next epoch are considered for buffering
* (concretely: early Finished messages). */
if( rec_epoch == (unsigned) ssl->in_epoch + 1 )
{
MBEDTLS_SSL_DEBUG_MSG( 2, ( "Consider record for buffering" ) );
return( MBEDTLS_ERR_SSL_EARLY_MESSAGE );
}
return( MBEDTLS_ERR_SSL_UNEXPECTED_RECORD );
}
#if defined(MBEDTLS_SSL_DTLS_ANTI_REPLAY)
/* For records from the correct epoch, check whether their
* sequence number has been seen before. */
else if( mbedtls_ssl_dtls_record_replay_check( (mbedtls_ssl_context *) ssl,
&rec->ctr[0] ) != 0 )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "replayed record" ) );
return( MBEDTLS_ERR_SSL_UNEXPECTED_RECORD );
}
#endif
}
#endif /* MBEDTLS_SSL_PROTO_DTLS */
return( 0 );
}
#if defined(MBEDTLS_SSL_DTLS_CLIENT_PORT_REUSE) && defined(MBEDTLS_SSL_SRV_C)
static int ssl_check_client_reconnect( mbedtls_ssl_context *ssl )
{
unsigned int rec_epoch = ( ssl->in_ctr[0] << 8 ) | ssl->in_ctr[1];
/*
* Check for an epoch 0 ClientHello. We can't use in_msg here to
* access the first byte of record content (handshake type), as we
* have an active transform (possibly iv_len != 0), so use the
* fact that the record header len is 13 instead.
*/
if( rec_epoch == 0 &&
ssl->conf->endpoint == MBEDTLS_SSL_IS_SERVER &&
ssl->state == MBEDTLS_SSL_HANDSHAKE_OVER &&
ssl->in_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE &&
ssl->in_left > 13 &&
ssl->in_buf[13] == MBEDTLS_SSL_HS_CLIENT_HELLO )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "possible client reconnect "
"from the same port" ) );
return( ssl_handle_possible_reconnect( ssl ) );
}
return( 0 );
}
#endif /* MBEDTLS_SSL_DTLS_CLIENT_PORT_REUSE && MBEDTLS_SSL_SRV_C */
/*
* If applicable, decrypt record content
*/
static int ssl_prepare_record_content( mbedtls_ssl_context *ssl,
mbedtls_record *rec )
{
int ret, done = 0;
MBEDTLS_SSL_DEBUG_BUF( 4, "input record from network",
rec->buf, rec->buf_len );
if( !done && ssl->transform_in != NULL )
{
unsigned char const old_msg_type = rec->type;
if( ( ret = mbedtls_ssl_decrypt_buf( ssl, ssl->transform_in,
rec ) ) != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "ssl_decrypt_buf", ret );
#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
if( ret == MBEDTLS_ERR_SSL_UNEXPECTED_CID &&
ssl->conf->ignore_unexpected_cid
== MBEDTLS_SSL_UNEXPECTED_CID_IGNORE )
{
MBEDTLS_SSL_DEBUG_MSG( 3, ( "ignoring unexpected CID" ) );
ret = MBEDTLS_ERR_SSL_CONTINUE_PROCESSING;
}
#endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
return( ret );
}
if( old_msg_type != rec->type )
{
MBEDTLS_SSL_DEBUG_MSG( 4, ( "record type after decrypt (before %d): %d",
old_msg_type, rec->type ) );
}
MBEDTLS_SSL_DEBUG_BUF( 4, "input payload after decrypt",
rec->buf + rec->data_offset, rec->data_len );
#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
/* We have already checked the record content type
* in ssl_parse_record_header(), failing or silently
* dropping the record in the case of an unknown type.
*
* Since with the use of CIDs, the record content type
* might change during decryption, re-check the record
* content type, but treat a failure as fatal this time. */
if( ssl_check_record_type( rec->type ) )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "unknown record type" ) );
return( MBEDTLS_ERR_SSL_INVALID_RECORD );
}
#endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
if( rec->data_len == 0 )
{
#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
if( ssl->minor_ver == MBEDTLS_SSL_MINOR_VERSION_3
&& rec->type != MBEDTLS_SSL_MSG_APPLICATION_DATA )
{
/* TLS v1.2 explicitly disallows zero-length messages which are not application data */
MBEDTLS_SSL_DEBUG_MSG( 1, ( "invalid zero-length message type: %d", ssl->in_msgtype ) );
return( MBEDTLS_ERR_SSL_INVALID_RECORD );
}
#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
ssl->nb_zero++;
/*
* Three or more empty messages may be a DoS attack
* (excessive CPU consumption).
*/
if( ssl->nb_zero > 3 )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "received four consecutive empty "
"messages, possible DoS attack" ) );
/* Treat the records as if they were not properly authenticated,
* thereby failing the connection if we see more than allowed
* by the configured bad MAC threshold. */
return( MBEDTLS_ERR_SSL_INVALID_MAC );
}
}
else
ssl->nb_zero = 0;
#if defined(MBEDTLS_SSL_PROTO_DTLS)
if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
{
; /* in_ctr read from peer, not maintained internally */
}
else
#endif
{
unsigned i;
for( i = 8; i > mbedtls_ssl_ep_len( ssl ); i-- )
if( ++ssl->in_ctr[i - 1] != 0 )
break;
/* The loop goes to its end iff the counter is wrapping */
if( i == mbedtls_ssl_ep_len( ssl ) )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "incoming message counter would wrap" ) );
return( MBEDTLS_ERR_SSL_COUNTER_WRAPPING );
}
}
}
#if defined(MBEDTLS_SSL_DTLS_ANTI_REPLAY)
if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
{
mbedtls_ssl_dtls_replay_update( ssl );
}
#endif
/* Check actual (decrypted) record content length against
* configured maximum. */
if( ssl->in_msglen > MBEDTLS_SSL_IN_CONTENT_LEN )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad message length" ) );
return( MBEDTLS_ERR_SSL_INVALID_RECORD );
}
return( 0 );
}
/*
* Read a record.
*
* Silently ignore non-fatal alert (and for DTLS, invalid records as well,
* RFC 6347 4.1.2.7) and continue reading until a valid record is found.
*
*/
/* Helper functions for mbedtls_ssl_read_record(). */
static int ssl_consume_current_message( mbedtls_ssl_context *ssl );
static int ssl_get_next_record( mbedtls_ssl_context *ssl );
static int ssl_record_is_in_progress( mbedtls_ssl_context *ssl );
int mbedtls_ssl_read_record( mbedtls_ssl_context *ssl,
unsigned update_hs_digest )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> read record" ) );
if( ssl->keep_current_message == 0 )
{
do {
ret = ssl_consume_current_message( ssl );
if( ret != 0 )
return( ret );
if( ssl_record_is_in_progress( ssl ) == 0 )
{
#if defined(MBEDTLS_SSL_PROTO_DTLS)
int have_buffered = 0;
/* We only check for buffered messages if the
* current datagram is fully consumed. */
if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
ssl_next_record_is_in_datagram( ssl ) == 0 )
{
if( ssl_load_buffered_message( ssl ) == 0 )
have_buffered = 1;
}
if( have_buffered == 0 )
#endif /* MBEDTLS_SSL_PROTO_DTLS */
{
ret = ssl_get_next_record( ssl );
if( ret == MBEDTLS_ERR_SSL_CONTINUE_PROCESSING )
continue;
if( ret != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, ( "ssl_get_next_record" ), ret );
return( ret );
}
}
}
ret = mbedtls_ssl_handle_message_type( ssl );
#if defined(MBEDTLS_SSL_PROTO_DTLS)
if( ret == MBEDTLS_ERR_SSL_EARLY_MESSAGE )
{
/* Buffer future message */
ret = ssl_buffer_message( ssl );
if( ret != 0 )
return( ret );
ret = MBEDTLS_ERR_SSL_CONTINUE_PROCESSING;
}
#endif /* MBEDTLS_SSL_PROTO_DTLS */
} while( MBEDTLS_ERR_SSL_NON_FATAL == ret ||
MBEDTLS_ERR_SSL_CONTINUE_PROCESSING == ret );
if( 0 != ret )
{
MBEDTLS_SSL_DEBUG_RET( 1, ( "mbedtls_ssl_handle_message_type" ), ret );
return( ret );
}
if( ssl->in_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE &&
update_hs_digest == 1 )
{
mbedtls_ssl_update_handshake_status( ssl );
}
}
else
{
MBEDTLS_SSL_DEBUG_MSG( 2, ( "reuse previously read message" ) );
ssl->keep_current_message = 0;
}
MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= read record" ) );
return( 0 );
}
#if defined(MBEDTLS_SSL_PROTO_DTLS)
static int ssl_next_record_is_in_datagram( mbedtls_ssl_context *ssl )
{
if( ssl->in_left > ssl->next_record_offset )
return( 1 );
return( 0 );
}
static int ssl_load_buffered_message( mbedtls_ssl_context *ssl )
{
mbedtls_ssl_handshake_params * const hs = ssl->handshake;
mbedtls_ssl_hs_buffer * hs_buf;
int ret = 0;
if( hs == NULL )
return( -1 );
MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> ssl_load_buffered_messsage" ) );
if( ssl->state == MBEDTLS_SSL_CLIENT_CHANGE_CIPHER_SPEC ||
ssl->state == MBEDTLS_SSL_SERVER_CHANGE_CIPHER_SPEC )
{
/* Check if we have seen a ChangeCipherSpec before.
* If yes, synthesize a CCS record. */
if( !hs->buffering.seen_ccs )
{
MBEDTLS_SSL_DEBUG_MSG( 2, ( "CCS not seen in the current flight" ) );
ret = -1;
goto exit;
}
MBEDTLS_SSL_DEBUG_MSG( 2, ( "Injecting buffered CCS message" ) );
ssl->in_msgtype = MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC;
ssl->in_msglen = 1;
ssl->in_msg[0] = 1;
/* As long as they are equal, the exact value doesn't matter. */
ssl->in_left = 0;
ssl->next_record_offset = 0;
hs->buffering.seen_ccs = 0;
goto exit;
}
#if defined(MBEDTLS_DEBUG_C)
/* Debug only */
{
unsigned offset;
for( offset = 1; offset < MBEDTLS_SSL_MAX_BUFFERED_HS; offset++ )
{
hs_buf = &hs->buffering.hs[offset];
if( hs_buf->is_valid == 1 )
{
MBEDTLS_SSL_DEBUG_MSG( 2, ( "Future message with sequence number %u %s buffered.",
hs->in_msg_seq + offset,
hs_buf->is_complete ? "fully" : "partially" ) );
}
}
}
#endif /* MBEDTLS_DEBUG_C */
/* Check if we have buffered and/or fully reassembled the
* next handshake message. */
hs_buf = &hs->buffering.hs[0];
if( ( hs_buf->is_valid == 1 ) && ( hs_buf->is_complete == 1 ) )
{
/* Synthesize a record containing the buffered HS message. */
size_t msg_len = ( hs_buf->data[1] << 16 ) |
( hs_buf->data[2] << 8 ) |
hs_buf->data[3];
/* Double-check that we haven't accidentally buffered
* a message that doesn't fit into the input buffer. */
if( msg_len + 12 > MBEDTLS_SSL_IN_CONTENT_LEN )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
}
MBEDTLS_SSL_DEBUG_MSG( 2, ( "Next handshake message has been buffered - load" ) );
MBEDTLS_SSL_DEBUG_BUF( 3, "Buffered handshake message (incl. header)",
hs_buf->data, msg_len + 12 );
ssl->in_msgtype = MBEDTLS_SSL_MSG_HANDSHAKE;
ssl->in_hslen = msg_len + 12;
ssl->in_msglen = msg_len + 12;
memcpy( ssl->in_msg, hs_buf->data, ssl->in_hslen );
ret = 0;
goto exit;
}
else
{
MBEDTLS_SSL_DEBUG_MSG( 2, ( "Next handshake message %u not or only partially bufffered",
hs->in_msg_seq ) );
}
ret = -1;
exit:
MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= ssl_load_buffered_message" ) );
return( ret );
}
static int ssl_buffer_make_space( mbedtls_ssl_context *ssl,
size_t desired )
{
int offset;
mbedtls_ssl_handshake_params * const hs = ssl->handshake;
MBEDTLS_SSL_DEBUG_MSG( 2, ( "Attempt to free buffered messages to have %u bytes available",
(unsigned) desired ) );
/* Get rid of future records epoch first, if such exist. */
ssl_free_buffered_record( ssl );
/* Check if we have enough space available now. */
if( desired <= ( MBEDTLS_SSL_DTLS_MAX_BUFFERING -
hs->buffering.total_bytes_buffered ) )
{
MBEDTLS_SSL_DEBUG_MSG( 2, ( "Enough space available after freeing future epoch record" ) );
return( 0 );
}
/* We don't have enough space to buffer the next expected handshake
* message. Remove buffers used for future messages to gain space,
* starting with the most distant one. */
for( offset = MBEDTLS_SSL_MAX_BUFFERED_HS - 1;
offset >= 0; offset-- )
{
MBEDTLS_SSL_DEBUG_MSG( 2, ( "Free buffering slot %d to make space for reassembly of next handshake message",
offset ) );
ssl_buffering_free_slot( ssl, (uint8_t) offset );
/* Check if we have enough space available now. */
if( desired <= ( MBEDTLS_SSL_DTLS_MAX_BUFFERING -
hs->buffering.total_bytes_buffered ) )
{
MBEDTLS_SSL_DEBUG_MSG( 2, ( "Enough space available after freeing buffered HS messages" ) );
return( 0 );
}
}
return( -1 );
}
static int ssl_buffer_message( mbedtls_ssl_context *ssl )
{
int ret = 0;
mbedtls_ssl_handshake_params * const hs = ssl->handshake;
if( hs == NULL )
return( 0 );
MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> ssl_buffer_message" ) );
switch( ssl->in_msgtype )
{
case MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC:
MBEDTLS_SSL_DEBUG_MSG( 2, ( "Remember CCS message" ) );
hs->buffering.seen_ccs = 1;
break;
case MBEDTLS_SSL_MSG_HANDSHAKE:
{
unsigned recv_msg_seq_offset;
unsigned recv_msg_seq = ( ssl->in_msg[4] << 8 ) | ssl->in_msg[5];
mbedtls_ssl_hs_buffer *hs_buf;
size_t msg_len = ssl->in_hslen - 12;
/* We should never receive an old handshake
* message - double-check nonetheless. */
if( recv_msg_seq < ssl->handshake->in_msg_seq )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
}
recv_msg_seq_offset = recv_msg_seq - ssl->handshake->in_msg_seq;
if( recv_msg_seq_offset >= MBEDTLS_SSL_MAX_BUFFERED_HS )
{
/* Silently ignore -- message too far in the future */
MBEDTLS_SSL_DEBUG_MSG( 2,
( "Ignore future HS message with sequence number %u, "
"buffering window %u - %u",
recv_msg_seq, ssl->handshake->in_msg_seq,
ssl->handshake->in_msg_seq + MBEDTLS_SSL_MAX_BUFFERED_HS - 1 ) );
goto exit;
}
MBEDTLS_SSL_DEBUG_MSG( 2, ( "Buffering HS message with sequence number %u, offset %u ",
recv_msg_seq, recv_msg_seq_offset ) );
hs_buf = &hs->buffering.hs[ recv_msg_seq_offset ];
/* Check if the buffering for this seq nr has already commenced. */
if( !hs_buf->is_valid )
{
size_t reassembly_buf_sz;
hs_buf->is_fragmented =
( ssl_hs_is_proper_fragment( ssl ) == 1 );
/* We copy the message back into the input buffer
* after reassembly, so check that it's not too large.
* This is an implementation-specific limitation
* and not one from the standard, hence it is not
* checked in ssl_check_hs_header(). */
if( msg_len + 12 > MBEDTLS_SSL_IN_CONTENT_LEN )
{
/* Ignore message */
goto exit;
}
/* Check if we have enough space to buffer the message. */
if( hs->buffering.total_bytes_buffered >
MBEDTLS_SSL_DTLS_MAX_BUFFERING )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
}
reassembly_buf_sz = ssl_get_reassembly_buffer_size( msg_len,
hs_buf->is_fragmented );
if( reassembly_buf_sz > ( MBEDTLS_SSL_DTLS_MAX_BUFFERING -
hs->buffering.total_bytes_buffered ) )
{
if( recv_msg_seq_offset > 0 )
{
/* If we can't buffer a future message because
* of space limitations -- ignore. */
MBEDTLS_SSL_DEBUG_MSG( 2, ( "Buffering of future message of size %" MBEDTLS_PRINTF_SIZET
" would exceed the compile-time limit %" MBEDTLS_PRINTF_SIZET
" (already %" MBEDTLS_PRINTF_SIZET
" bytes buffered) -- ignore\n",
msg_len, (size_t) MBEDTLS_SSL_DTLS_MAX_BUFFERING,
hs->buffering.total_bytes_buffered ) );
goto exit;
}
else
{
MBEDTLS_SSL_DEBUG_MSG( 2, ( "Buffering of future message of size %" MBEDTLS_PRINTF_SIZET
" would exceed the compile-time limit %" MBEDTLS_PRINTF_SIZET
" (already %" MBEDTLS_PRINTF_SIZET
" bytes buffered) -- attempt to make space by freeing buffered future messages\n",
msg_len, (size_t) MBEDTLS_SSL_DTLS_MAX_BUFFERING,
hs->buffering.total_bytes_buffered ) );
}
if( ssl_buffer_make_space( ssl, reassembly_buf_sz ) != 0 )
{
MBEDTLS_SSL_DEBUG_MSG( 2, ( "Reassembly of next message of size %" MBEDTLS_PRINTF_SIZET
" (%" MBEDTLS_PRINTF_SIZET " with bitmap) would exceed"
" the compile-time limit %" MBEDTLS_PRINTF_SIZET
" (already %" MBEDTLS_PRINTF_SIZET
" bytes buffered) -- fail\n",
msg_len,
reassembly_buf_sz,
(size_t) MBEDTLS_SSL_DTLS_MAX_BUFFERING,
hs->buffering.total_bytes_buffered ) );
ret = MBEDTLS_ERR_SSL_BUFFER_TOO_SMALL;
goto exit;
}
}
MBEDTLS_SSL_DEBUG_MSG( 2, ( "initialize reassembly, total length = %" MBEDTLS_PRINTF_SIZET,
msg_len ) );
hs_buf->data = mbedtls_calloc( 1, reassembly_buf_sz );
if( hs_buf->data == NULL )
{
ret = MBEDTLS_ERR_SSL_ALLOC_FAILED;
goto exit;
}
hs_buf->data_len = reassembly_buf_sz;
/* Prepare final header: copy msg_type, length and message_seq,
* then add standardised fragment_offset and fragment_length */
memcpy( hs_buf->data, ssl->in_msg, 6 );
memset( hs_buf->data + 6, 0, 3 );
memcpy( hs_buf->data + 9, hs_buf->data + 1, 3 );
hs_buf->is_valid = 1;
hs->buffering.total_bytes_buffered += reassembly_buf_sz;
}
else
{
/* Make sure msg_type and length are consistent */
if( memcmp( hs_buf->data, ssl->in_msg, 4 ) != 0 )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "Fragment header mismatch - ignore" ) );
/* Ignore */
goto exit;
}
}
if( !hs_buf->is_complete )
{
size_t frag_len, frag_off;
unsigned char * const msg = hs_buf->data + 12;
/*
* Check and copy current fragment
*/
/* Validation of header fields already done in
* mbedtls_ssl_prepare_handshake_record(). */
frag_off = ssl_get_hs_frag_off( ssl );
frag_len = ssl_get_hs_frag_len( ssl );
MBEDTLS_SSL_DEBUG_MSG( 2, ( "adding fragment, offset = %" MBEDTLS_PRINTF_SIZET
", length = %" MBEDTLS_PRINTF_SIZET,
frag_off, frag_len ) );
memcpy( msg + frag_off, ssl->in_msg + 12, frag_len );
if( hs_buf->is_fragmented )
{
unsigned char * const bitmask = msg + msg_len;
ssl_bitmask_set( bitmask, frag_off, frag_len );
hs_buf->is_complete = ( ssl_bitmask_check( bitmask,
msg_len ) == 0 );
}
else
{
hs_buf->is_complete = 1;
}
MBEDTLS_SSL_DEBUG_MSG( 2, ( "message %scomplete",
hs_buf->is_complete ? "" : "not yet " ) );
}
break;
}
default:
/* We don't buffer other types of messages. */
break;
}
exit:
MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= ssl_buffer_message" ) );
return( ret );
}
#endif /* MBEDTLS_SSL_PROTO_DTLS */
static int ssl_consume_current_message( mbedtls_ssl_context *ssl )
{
/*
* Consume last content-layer message and potentially
* update in_msglen which keeps track of the contents'
* consumption state.
*
* (1) Handshake messages:
* Remove last handshake message, move content
* and adapt in_msglen.
*
* (2) Alert messages:
* Consume whole record content, in_msglen = 0.
*
* (3) Change cipher spec:
* Consume whole record content, in_msglen = 0.
*
* (4) Application data:
* Don't do anything - the record layer provides
* the application data as a stream transport
* and consumes through mbedtls_ssl_read only.
*
*/
/* Case (1): Handshake messages */
if( ssl->in_hslen != 0 )
{
/* Hard assertion to be sure that no application data
* is in flight, as corrupting ssl->in_msglen during
* ssl->in_offt != NULL is fatal. */
if( ssl->in_offt != NULL )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
}
/*
* Get next Handshake message in the current record
*/
/* Notes:
* (1) in_hslen is not necessarily the size of the
* current handshake content: If DTLS handshake
* fragmentation is used, that's the fragment
* size instead. Using the total handshake message
* size here is faulty and should be changed at
* some point.
* (2) While it doesn't seem to cause problems, one
* has to be very careful not to assume that in_hslen
* is always <= in_msglen in a sensible communication.
* Again, it's wrong for DTLS handshake fragmentation.
* The following check is therefore mandatory, and
* should not be treated as a silently corrected assertion.
* Additionally, ssl->in_hslen might be arbitrarily out of
* bounds after handling a DTLS message with an unexpected
* sequence number, see mbedtls_ssl_prepare_handshake_record.
*/
if( ssl->in_hslen < ssl->in_msglen )
{
ssl->in_msglen -= ssl->in_hslen;
memmove( ssl->in_msg, ssl->in_msg + ssl->in_hslen,
ssl->in_msglen );
MBEDTLS_SSL_DEBUG_BUF( 4, "remaining content in record",
ssl->in_msg, ssl->in_msglen );
}
else
{
ssl->in_msglen = 0;
}
ssl->in_hslen = 0;
}
/* Case (4): Application data */
else if( ssl->in_offt != NULL )
{
return( 0 );
}
/* Everything else (CCS & Alerts) */
else
{
ssl->in_msglen = 0;
}
return( 0 );
}
static int ssl_record_is_in_progress( mbedtls_ssl_context *ssl )
{
if( ssl->in_msglen > 0 )
return( 1 );
return( 0 );
}
#if defined(MBEDTLS_SSL_PROTO_DTLS)
static void ssl_free_buffered_record( mbedtls_ssl_context *ssl )
{
mbedtls_ssl_handshake_params * const hs = ssl->handshake;
if( hs == NULL )
return;
if( hs->buffering.future_record.data != NULL )
{
hs->buffering.total_bytes_buffered -=
hs->buffering.future_record.len;
mbedtls_free( hs->buffering.future_record.data );
hs->buffering.future_record.data = NULL;
}
}
static int ssl_load_buffered_record( mbedtls_ssl_context *ssl )
{
mbedtls_ssl_handshake_params * const hs = ssl->handshake;
unsigned char * rec;
size_t rec_len;
unsigned rec_epoch;
#if defined(MBEDTLS_SSL_VARIABLE_BUFFER_LENGTH)
size_t in_buf_len = ssl->in_buf_len;
#else
size_t in_buf_len = MBEDTLS_SSL_IN_BUFFER_LEN;
#endif
if( ssl->conf->transport != MBEDTLS_SSL_TRANSPORT_DATAGRAM )
return( 0 );
if( hs == NULL )
return( 0 );
rec = hs->buffering.future_record.data;
rec_len = hs->buffering.future_record.len;
rec_epoch = hs->buffering.future_record.epoch;
if( rec == NULL )
return( 0 );
/* Only consider loading future records if the
* input buffer is empty. */
if( ssl_next_record_is_in_datagram( ssl ) == 1 )
return( 0 );
MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> ssl_load_buffered_record" ) );
if( rec_epoch != ssl->in_epoch )
{
MBEDTLS_SSL_DEBUG_MSG( 2, ( "Buffered record not from current epoch." ) );
goto exit;
}
MBEDTLS_SSL_DEBUG_MSG( 2, ( "Found buffered record from current epoch - load" ) );
/* Double-check that the record is not too large */
if( rec_len > in_buf_len - (size_t)( ssl->in_hdr - ssl->in_buf ) )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
}
memcpy( ssl->in_hdr, rec, rec_len );
ssl->in_left = rec_len;
ssl->next_record_offset = 0;
ssl_free_buffered_record( ssl );
exit:
MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= ssl_load_buffered_record" ) );
return( 0 );
}
static int ssl_buffer_future_record( mbedtls_ssl_context *ssl,
mbedtls_record const *rec )
{
mbedtls_ssl_handshake_params * const hs = ssl->handshake;
/* Don't buffer future records outside handshakes. */
if( hs == NULL )
return( 0 );
/* Only buffer handshake records (we are only interested
* in Finished messages). */
if( rec->type != MBEDTLS_SSL_MSG_HANDSHAKE )
return( 0 );
/* Don't buffer more than one future epoch record. */
if( hs->buffering.future_record.data != NULL )
return( 0 );
/* Don't buffer record if there's not enough buffering space remaining. */
if( rec->buf_len > ( MBEDTLS_SSL_DTLS_MAX_BUFFERING -
hs->buffering.total_bytes_buffered ) )
{
MBEDTLS_SSL_DEBUG_MSG( 2, ( "Buffering of future epoch record of size %" MBEDTLS_PRINTF_SIZET
" would exceed the compile-time limit %" MBEDTLS_PRINTF_SIZET
" (already %" MBEDTLS_PRINTF_SIZET
" bytes buffered) -- ignore\n",
rec->buf_len, (size_t) MBEDTLS_SSL_DTLS_MAX_BUFFERING,
hs->buffering.total_bytes_buffered ) );
return( 0 );
}
/* Buffer record */
MBEDTLS_SSL_DEBUG_MSG( 2, ( "Buffer record from epoch %u",
ssl->in_epoch + 1U ) );
MBEDTLS_SSL_DEBUG_BUF( 3, "Buffered record", rec->buf, rec->buf_len );
/* ssl_parse_record_header() only considers records
* of the next epoch as candidates for buffering. */
hs->buffering.future_record.epoch = ssl->in_epoch + 1;
hs->buffering.future_record.len = rec->buf_len;
hs->buffering.future_record.data =
mbedtls_calloc( 1, hs->buffering.future_record.len );
if( hs->buffering.future_record.data == NULL )
{
/* If we run out of RAM trying to buffer a
* record from the next epoch, just ignore. */
return( 0 );
}
memcpy( hs->buffering.future_record.data, rec->buf, rec->buf_len );
hs->buffering.total_bytes_buffered += rec->buf_len;
return( 0 );
}
#endif /* MBEDTLS_SSL_PROTO_DTLS */
static int ssl_get_next_record( mbedtls_ssl_context *ssl )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
mbedtls_record rec;
#if defined(MBEDTLS_SSL_PROTO_DTLS)
/* We might have buffered a future record; if so,
* and if the epoch matches now, load it.
* On success, this call will set ssl->in_left to
* the length of the buffered record, so that
* the calls to ssl_fetch_input() below will
* essentially be no-ops. */
ret = ssl_load_buffered_record( ssl );
if( ret != 0 )
return( ret );
#endif /* MBEDTLS_SSL_PROTO_DTLS */
/* Ensure that we have enough space available for the default form
* of TLS / DTLS record headers (5 Bytes for TLS, 13 Bytes for DTLS,
* with no space for CIDs counted in). */
ret = mbedtls_ssl_fetch_input( ssl, mbedtls_ssl_in_hdr_len( ssl ) );
if( ret != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_fetch_input", ret );
return( ret );
}
ret = ssl_parse_record_header( ssl, ssl->in_hdr, ssl->in_left, &rec );
if( ret != 0 )
{
#if defined(MBEDTLS_SSL_PROTO_DTLS)
if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
{
if( ret == MBEDTLS_ERR_SSL_EARLY_MESSAGE )
{
ret = ssl_buffer_future_record( ssl, &rec );
if( ret != 0 )
return( ret );
/* Fall through to handling of unexpected records */
ret = MBEDTLS_ERR_SSL_UNEXPECTED_RECORD;
}
if( ret == MBEDTLS_ERR_SSL_UNEXPECTED_RECORD )
{
#if defined(MBEDTLS_SSL_DTLS_CLIENT_PORT_REUSE) && defined(MBEDTLS_SSL_SRV_C)
/* Reset in pointers to default state for TLS/DTLS records,
* assuming no CID and no offset between record content and
* record plaintext. */
mbedtls_ssl_update_in_pointers( ssl );
/* Setup internal message pointers from record structure. */
ssl->in_msgtype = rec.type;
#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
ssl->in_len = ssl->in_cid + rec.cid_len;
#endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
ssl->in_iv = ssl->in_msg = ssl->in_len + 2;
ssl->in_msglen = rec.data_len;
ret = ssl_check_client_reconnect( ssl );
MBEDTLS_SSL_DEBUG_RET( 2, "ssl_check_client_reconnect", ret );
if( ret != 0 )
return( ret );
#endif
/* Skip unexpected record (but not whole datagram) */
ssl->next_record_offset = rec.buf_len;
MBEDTLS_SSL_DEBUG_MSG( 1, ( "discarding unexpected record "
"(header)" ) );
}
else
{
/* Skip invalid record and the rest of the datagram */
ssl->next_record_offset = 0;
ssl->in_left = 0;
MBEDTLS_SSL_DEBUG_MSG( 1, ( "discarding invalid record "
"(header)" ) );
}
/* Get next record */
return( MBEDTLS_ERR_SSL_CONTINUE_PROCESSING );
}
else
#endif
{
return( ret );
}
}
#if defined(MBEDTLS_SSL_PROTO_DTLS)
if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
{
/* Remember offset of next record within datagram. */
ssl->next_record_offset = rec.buf_len;
if( ssl->next_record_offset < ssl->in_left )
{
MBEDTLS_SSL_DEBUG_MSG( 3, ( "more than one record within datagram" ) );
}
}
else
#endif
{
/*
* Fetch record contents from underlying transport.
*/
ret = mbedtls_ssl_fetch_input( ssl, rec.buf_len );
if( ret != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_fetch_input", ret );
return( ret );
}
ssl->in_left = 0;
}
/*
* Decrypt record contents.
*/
if( ( ret = ssl_prepare_record_content( ssl, &rec ) ) != 0 )
{
#if defined(MBEDTLS_SSL_PROTO_DTLS)
if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
{
/* Silently discard invalid records */
if( ret == MBEDTLS_ERR_SSL_INVALID_MAC )
{
/* Except when waiting for Finished as a bad mac here
* probably means something went wrong in the handshake
* (eg wrong psk used, mitm downgrade attempt, etc.) */
if( ssl->state == MBEDTLS_SSL_CLIENT_FINISHED ||
ssl->state == MBEDTLS_SSL_SERVER_FINISHED )
{
#if defined(MBEDTLS_SSL_ALL_ALERT_MESSAGES)
if( ret == MBEDTLS_ERR_SSL_INVALID_MAC )
{
mbedtls_ssl_send_alert_message( ssl,
MBEDTLS_SSL_ALERT_LEVEL_FATAL,
MBEDTLS_SSL_ALERT_MSG_BAD_RECORD_MAC );
}
#endif
return( ret );
}
#if defined(MBEDTLS_SSL_DTLS_BADMAC_LIMIT)
if( ssl->conf->badmac_limit != 0 &&
++ssl->badmac_seen >= ssl->conf->badmac_limit )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "too many records with bad MAC" ) );
return( MBEDTLS_ERR_SSL_INVALID_MAC );
}
#endif
/* As above, invalid records cause
* dismissal of the whole datagram. */
ssl->next_record_offset = 0;
ssl->in_left = 0;
MBEDTLS_SSL_DEBUG_MSG( 1, ( "discarding invalid record (mac)" ) );
return( MBEDTLS_ERR_SSL_CONTINUE_PROCESSING );
}
return( ret );
}
else
#endif
{
/* Error out (and send alert) on invalid records */
#if defined(MBEDTLS_SSL_ALL_ALERT_MESSAGES)
if( ret == MBEDTLS_ERR_SSL_INVALID_MAC )
{
mbedtls_ssl_send_alert_message( ssl,
MBEDTLS_SSL_ALERT_LEVEL_FATAL,
MBEDTLS_SSL_ALERT_MSG_BAD_RECORD_MAC );
}
#endif
return( ret );
}
}
/* Reset in pointers to default state for TLS/DTLS records,
* assuming no CID and no offset between record content and
* record plaintext. */
mbedtls_ssl_update_in_pointers( ssl );
#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
ssl->in_len = ssl->in_cid + rec.cid_len;
#endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
ssl->in_iv = ssl->in_len + 2;
/* The record content type may change during decryption,
* so re-read it. */
ssl->in_msgtype = rec.type;
/* Also update the input buffer, because unfortunately
* the server-side ssl_parse_client_hello() reparses the
* record header when receiving a ClientHello initiating
* a renegotiation. */
ssl->in_hdr[0] = rec.type;
ssl->in_msg = rec.buf + rec.data_offset;
ssl->in_msglen = rec.data_len;
ssl->in_len[0] = (unsigned char)( rec.data_len >> 8 );
ssl->in_len[1] = (unsigned char)( rec.data_len );
return( 0 );
}
int mbedtls_ssl_handle_message_type( mbedtls_ssl_context *ssl )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
/*
* Handle particular types of records
*/
if( ssl->in_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE )
{
if( ( ret = mbedtls_ssl_prepare_handshake_record( ssl ) ) != 0 )
{
return( ret );
}
}
if( ssl->in_msgtype == MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC )
{
if( ssl->in_msglen != 1 )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "invalid CCS message, len: %" MBEDTLS_PRINTF_SIZET,
ssl->in_msglen ) );
return( MBEDTLS_ERR_SSL_INVALID_RECORD );
}
if( ssl->in_msg[0] != 1 )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "invalid CCS message, content: %02x",
ssl->in_msg[0] ) );
return( MBEDTLS_ERR_SSL_INVALID_RECORD );
}
#if defined(MBEDTLS_SSL_PROTO_DTLS)
if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
ssl->state != MBEDTLS_SSL_CLIENT_CHANGE_CIPHER_SPEC &&
ssl->state != MBEDTLS_SSL_SERVER_CHANGE_CIPHER_SPEC )
{
if( ssl->handshake == NULL )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "dropping ChangeCipherSpec outside handshake" ) );
return( MBEDTLS_ERR_SSL_UNEXPECTED_RECORD );
}
MBEDTLS_SSL_DEBUG_MSG( 1, ( "received out-of-order ChangeCipherSpec - remember" ) );
return( MBEDTLS_ERR_SSL_EARLY_MESSAGE );
}
#endif
}
if( ssl->in_msgtype == MBEDTLS_SSL_MSG_ALERT )
{
if( ssl->in_msglen != 2 )
{
/* Note: Standard allows for more than one 2 byte alert
to be packed in a single message, but Mbed TLS doesn't
currently support this. */
MBEDTLS_SSL_DEBUG_MSG( 1, ( "invalid alert message, len: %" MBEDTLS_PRINTF_SIZET,
ssl->in_msglen ) );
return( MBEDTLS_ERR_SSL_INVALID_RECORD );
}
MBEDTLS_SSL_DEBUG_MSG( 2, ( "got an alert message, type: [%u:%u]",
ssl->in_msg[0], ssl->in_msg[1] ) );
/*
* Ignore non-fatal alerts, except close_notify and no_renegotiation
*/
if( ssl->in_msg[0] == MBEDTLS_SSL_ALERT_LEVEL_FATAL )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "is a fatal alert message (msg %d)",
ssl->in_msg[1] ) );
return( MBEDTLS_ERR_SSL_FATAL_ALERT_MESSAGE );
}
if( ssl->in_msg[0] == MBEDTLS_SSL_ALERT_LEVEL_WARNING &&
ssl->in_msg[1] == MBEDTLS_SSL_ALERT_MSG_CLOSE_NOTIFY )
{
MBEDTLS_SSL_DEBUG_MSG( 2, ( "is a close notify message" ) );
return( MBEDTLS_ERR_SSL_PEER_CLOSE_NOTIFY );
}
#if defined(MBEDTLS_SSL_RENEGOTIATION_ENABLED)
if( ssl->in_msg[0] == MBEDTLS_SSL_ALERT_LEVEL_WARNING &&
ssl->in_msg[1] == MBEDTLS_SSL_ALERT_MSG_NO_RENEGOTIATION )
{
MBEDTLS_SSL_DEBUG_MSG( 2, ( "is a no renegotiation alert" ) );
/* Will be handled when trying to parse ServerHello */
return( 0 );
}
#endif
/* Silently ignore: fetch new message */
return MBEDTLS_ERR_SSL_NON_FATAL;
}
#if defined(MBEDTLS_SSL_PROTO_DTLS)
if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
{
/* Drop unexpected ApplicationData records,
* except at the beginning of renegotiations */
if( ssl->in_msgtype == MBEDTLS_SSL_MSG_APPLICATION_DATA &&
ssl->state != MBEDTLS_SSL_HANDSHAKE_OVER
#if defined(MBEDTLS_SSL_RENEGOTIATION)
&& ! ( ssl->renego_status == MBEDTLS_SSL_RENEGOTIATION_IN_PROGRESS &&
ssl->state == MBEDTLS_SSL_SERVER_HELLO )
#endif
)
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "dropping unexpected ApplicationData" ) );
return( MBEDTLS_ERR_SSL_NON_FATAL );
}
if( ssl->handshake != NULL &&
ssl->state == MBEDTLS_SSL_HANDSHAKE_OVER )
{
mbedtls_ssl_handshake_wrapup_free_hs_transform( ssl );
}
}
#endif /* MBEDTLS_SSL_PROTO_DTLS */
return( 0 );
}
int mbedtls_ssl_send_fatal_handshake_failure( mbedtls_ssl_context *ssl )
{
return( mbedtls_ssl_send_alert_message( ssl,
MBEDTLS_SSL_ALERT_LEVEL_FATAL,
MBEDTLS_SSL_ALERT_MSG_HANDSHAKE_FAILURE ) );
}
int mbedtls_ssl_send_alert_message( mbedtls_ssl_context *ssl,
unsigned char level,
unsigned char message )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
if( ssl == NULL || ssl->conf == NULL )
return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> send alert message" ) );
MBEDTLS_SSL_DEBUG_MSG( 3, ( "send alert level=%u message=%u", level, message ));
ssl->out_msgtype = MBEDTLS_SSL_MSG_ALERT;
ssl->out_msglen = 2;
ssl->out_msg[0] = level;
ssl->out_msg[1] = message;
if( ( ret = mbedtls_ssl_write_record( ssl, SSL_FORCE_FLUSH ) ) != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_write_record", ret );
return( ret );
}
MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= send alert message" ) );
return( 0 );
}
int mbedtls_ssl_write_change_cipher_spec( mbedtls_ssl_context *ssl )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write change cipher spec" ) );
ssl->out_msgtype = MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC;
ssl->out_msglen = 1;
ssl->out_msg[0] = 1;
ssl->state++;
if( ( ret = mbedtls_ssl_write_handshake_msg( ssl ) ) != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_write_handshake_msg", ret );
return( ret );
}
MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= write change cipher spec" ) );
return( 0 );
}
int mbedtls_ssl_parse_change_cipher_spec( mbedtls_ssl_context *ssl )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> parse change cipher spec" ) );
if( ( ret = mbedtls_ssl_read_record( ssl, 1 ) ) != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_read_record", ret );
return( ret );
}
if( ssl->in_msgtype != MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad change cipher spec message" ) );
mbedtls_ssl_send_alert_message( ssl, MBEDTLS_SSL_ALERT_LEVEL_FATAL,
MBEDTLS_SSL_ALERT_MSG_UNEXPECTED_MESSAGE );
return( MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE );
}
/* CCS records are only accepted if they have length 1 and content '1',
* so we don't need to check this here. */
/*
* Switch to our negotiated transform and session parameters for inbound
* data.
*/
MBEDTLS_SSL_DEBUG_MSG( 3, ( "switching to new transform spec for inbound data" ) );
ssl->transform_in = ssl->transform_negotiate;
ssl->session_in = ssl->session_negotiate;
#if defined(MBEDTLS_SSL_PROTO_DTLS)
if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
{
#if defined(MBEDTLS_SSL_DTLS_ANTI_REPLAY)
mbedtls_ssl_dtls_replay_reset( ssl );
#endif
/* Increment epoch */
if( ++ssl->in_epoch == 0 )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "DTLS epoch would wrap" ) );
/* This is highly unlikely to happen for legitimate reasons, so
treat it as an attack and don't send an alert. */
return( MBEDTLS_ERR_SSL_COUNTER_WRAPPING );
}
}
else
#endif /* MBEDTLS_SSL_PROTO_DTLS */
memset( ssl->in_ctr, 0, 8 );
mbedtls_ssl_update_in_pointers( ssl );
ssl->state++;
MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= parse change cipher spec" ) );
return( 0 );
}
/* Once ssl->out_hdr as the address of the beginning of the
* next outgoing record is set, deduce the other pointers.
*
* Note: For TLS, we save the implicit record sequence number
* (entering MAC computation) in the 8 bytes before ssl->out_hdr,
* and the caller has to make sure there's space for this.
*/
static size_t ssl_transform_get_explicit_iv_len(
mbedtls_ssl_transform const *transform )
{
if( transform->minor_ver < MBEDTLS_SSL_MINOR_VERSION_2 )
return( 0 );
return( transform->ivlen - transform->fixed_ivlen );
}
void mbedtls_ssl_update_out_pointers( mbedtls_ssl_context *ssl,
mbedtls_ssl_transform *transform )
{
#if defined(MBEDTLS_SSL_PROTO_DTLS)
if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
{
ssl->out_ctr = ssl->out_hdr + 3;
#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
ssl->out_cid = ssl->out_ctr + 8;
ssl->out_len = ssl->out_cid;
if( transform != NULL )
ssl->out_len += transform->out_cid_len;
#else /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
ssl->out_len = ssl->out_ctr + 8;
#endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
ssl->out_iv = ssl->out_len + 2;
}
else
#endif
{
ssl->out_ctr = ssl->out_hdr - 8;
ssl->out_len = ssl->out_hdr + 3;
#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
ssl->out_cid = ssl->out_len;
#endif
ssl->out_iv = ssl->out_hdr + 5;
}
ssl->out_msg = ssl->out_iv;
/* Adjust out_msg to make space for explicit IV, if used. */
if( transform != NULL )
ssl->out_msg += ssl_transform_get_explicit_iv_len( transform );
}
/* Once ssl->in_hdr as the address of the beginning of the
* next incoming record is set, deduce the other pointers.
*
* Note: For TLS, we save the implicit record sequence number
* (entering MAC computation) in the 8 bytes before ssl->in_hdr,
* and the caller has to make sure there's space for this.
*/
void mbedtls_ssl_update_in_pointers( mbedtls_ssl_context *ssl )
{
/* This function sets the pointers to match the case
* of unprotected TLS/DTLS records, with both ssl->in_iv
* and ssl->in_msg pointing to the beginning of the record
* content.
*
* When decrypting a protected record, ssl->in_msg
* will be shifted to point to the beginning of the
* record plaintext.
*/
#if defined(MBEDTLS_SSL_PROTO_DTLS)
if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
{
/* This sets the header pointers to match records
* without CID. When we receive a record containing
* a CID, the fields are shifted accordingly in
* ssl_parse_record_header(). */
ssl->in_ctr = ssl->in_hdr + 3;
#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
ssl->in_cid = ssl->in_ctr + 8;
ssl->in_len = ssl->in_cid; /* Default: no CID */
#else /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
ssl->in_len = ssl->in_ctr + 8;
#endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
ssl->in_iv = ssl->in_len + 2;
}
else
#endif
{
ssl->in_ctr = ssl->in_hdr - 8;
ssl->in_len = ssl->in_hdr + 3;
#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
ssl->in_cid = ssl->in_len;
#endif
ssl->in_iv = ssl->in_hdr + 5;
}
/* This will be adjusted at record decryption time. */
ssl->in_msg = ssl->in_iv;
}
/*
* Setup an SSL context
*/
void mbedtls_ssl_reset_in_out_pointers( mbedtls_ssl_context *ssl )
{
/* Set the incoming and outgoing record pointers. */
#if defined(MBEDTLS_SSL_PROTO_DTLS)
if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
{
ssl->out_hdr = ssl->out_buf;
ssl->in_hdr = ssl->in_buf;
}
else
#endif /* MBEDTLS_SSL_PROTO_DTLS */
{
ssl->out_hdr = ssl->out_buf + 8;
ssl->in_hdr = ssl->in_buf + 8;
}
/* Derive other internal pointers. */
mbedtls_ssl_update_out_pointers( ssl, NULL /* no transform enabled */ );
mbedtls_ssl_update_in_pointers ( ssl );
}
/*
* SSL get accessors
*/
size_t mbedtls_ssl_get_bytes_avail( const mbedtls_ssl_context *ssl )
{
return( ssl->in_offt == NULL ? 0 : ssl->in_msglen );
}
int mbedtls_ssl_check_pending( const mbedtls_ssl_context *ssl )
{
/*
* Case A: We're currently holding back
* a message for further processing.
*/
if( ssl->keep_current_message == 1 )
{
MBEDTLS_SSL_DEBUG_MSG( 3, ( "ssl_check_pending: record held back for processing" ) );
return( 1 );
}
/*
* Case B: Further records are pending in the current datagram.
*/
#if defined(MBEDTLS_SSL_PROTO_DTLS)
if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
ssl->in_left > ssl->next_record_offset )
{
MBEDTLS_SSL_DEBUG_MSG( 3, ( "ssl_check_pending: more records within current datagram" ) );
return( 1 );
}
#endif /* MBEDTLS_SSL_PROTO_DTLS */
/*
* Case C: A handshake message is being processed.
*/
if( ssl->in_hslen > 0 && ssl->in_hslen < ssl->in_msglen )
{
MBEDTLS_SSL_DEBUG_MSG( 3, ( "ssl_check_pending: more handshake messages within current record" ) );
return( 1 );
}
/*
* Case D: An application data message is being processed
*/
if( ssl->in_offt != NULL )
{
MBEDTLS_SSL_DEBUG_MSG( 3, ( "ssl_check_pending: application data record is being processed" ) );
return( 1 );
}
/*
* In all other cases, the rest of the message can be dropped.
* As in ssl_get_next_record, this needs to be adapted if
* we implement support for multiple alerts in single records.
*/
MBEDTLS_SSL_DEBUG_MSG( 3, ( "ssl_check_pending: nothing pending" ) );
return( 0 );
}
int mbedtls_ssl_get_record_expansion( const mbedtls_ssl_context *ssl )
{
size_t transform_expansion = 0;
const mbedtls_ssl_transform *transform = ssl->transform_out;
unsigned block_size;
size_t out_hdr_len = mbedtls_ssl_out_hdr_len( ssl );
if( transform == NULL )
return( (int) out_hdr_len );
switch( mbedtls_cipher_get_cipher_mode( &transform->cipher_ctx_enc ) )
{
case MBEDTLS_MODE_GCM:
case MBEDTLS_MODE_CCM:
case MBEDTLS_MODE_CHACHAPOLY:
case MBEDTLS_MODE_STREAM:
transform_expansion = transform->minlen;
break;
case MBEDTLS_MODE_CBC:
block_size = mbedtls_cipher_get_block_size(
&transform->cipher_ctx_enc );
/* Expansion due to the addition of the MAC. */
transform_expansion += transform->maclen;
/* Expansion due to the addition of CBC padding;
* Theoretically up to 256 bytes, but we never use
* more than the block size of the underlying cipher. */
transform_expansion += block_size;
/* For TLS 1.1 or higher, an explicit IV is added
* after the record header. */
#if defined(MBEDTLS_SSL_PROTO_TLS1_1) || defined(MBEDTLS_SSL_PROTO_TLS1_2)
if( ssl->minor_ver >= MBEDTLS_SSL_MINOR_VERSION_2 )
transform_expansion += block_size;
#endif /* MBEDTLS_SSL_PROTO_TLS1_1 || MBEDTLS_SSL_PROTO_TLS1_2 */
break;
default:
MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
}
#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
if( transform->out_cid_len != 0 )
transform_expansion += MBEDTLS_SSL_MAX_CID_EXPANSION;
#endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
return( (int)( out_hdr_len + transform_expansion ) );
}
#if defined(MBEDTLS_SSL_RENEGOTIATION)
/*
* Check record counters and renegotiate if they're above the limit.
*/
static int ssl_check_ctr_renegotiate( mbedtls_ssl_context *ssl )
{
size_t ep_len = mbedtls_ssl_ep_len( ssl );
int in_ctr_cmp;
int out_ctr_cmp;
if( ssl->state != MBEDTLS_SSL_HANDSHAKE_OVER ||
ssl->renego_status == MBEDTLS_SSL_RENEGOTIATION_PENDING ||
ssl->conf->disable_renegotiation == MBEDTLS_SSL_RENEGOTIATION_DISABLED )
{
return( 0 );
}
in_ctr_cmp = memcmp( ssl->in_ctr + ep_len,
ssl->conf->renego_period + ep_len, 8 - ep_len );
out_ctr_cmp = memcmp( ssl->cur_out_ctr + ep_len,
ssl->conf->renego_period + ep_len, 8 - ep_len );
if( in_ctr_cmp <= 0 && out_ctr_cmp <= 0 )
{
return( 0 );
}
MBEDTLS_SSL_DEBUG_MSG( 1, ( "record counter limit reached: renegotiate" ) );
return( mbedtls_ssl_renegotiate( ssl ) );
}
#endif /* MBEDTLS_SSL_RENEGOTIATION */
/*
* Receive application data decrypted from the SSL layer
*/
int mbedtls_ssl_read( mbedtls_ssl_context *ssl, unsigned char *buf, size_t len )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
size_t n;
if( ssl == NULL || ssl->conf == NULL )
return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> read" ) );
#if defined(MBEDTLS_SSL_PROTO_DTLS)
if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
{
if( ( ret = mbedtls_ssl_flush_output( ssl ) ) != 0 )
return( ret );
if( ssl->handshake != NULL &&
ssl->handshake->retransmit_state == MBEDTLS_SSL_RETRANS_SENDING )
{
if( ( ret = mbedtls_ssl_flight_transmit( ssl ) ) != 0 )
return( ret );
}
}
#endif
/*
* Check if renegotiation is necessary and/or handshake is
* in process. If yes, perform/continue, and fall through
* if an unexpected packet is received while the client
* is waiting for the ServerHello.
*
* (There is no equivalent to the last condition on
* the server-side as it is not treated as within
* a handshake while waiting for the ClientHello
* after a renegotiation request.)
*/
#if defined(MBEDTLS_SSL_RENEGOTIATION)
ret = ssl_check_ctr_renegotiate( ssl );
if( ret != MBEDTLS_ERR_SSL_WAITING_SERVER_HELLO_RENEGO &&
ret != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "ssl_check_ctr_renegotiate", ret );
return( ret );
}
#endif
if( ssl->state != MBEDTLS_SSL_HANDSHAKE_OVER )
{
ret = mbedtls_ssl_handshake( ssl );
if( ret != MBEDTLS_ERR_SSL_WAITING_SERVER_HELLO_RENEGO &&
ret != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_handshake", ret );
return( ret );
}
}
/* Loop as long as no application data record is available */
while( ssl->in_offt == NULL )
{
/* Start timer if not already running */
if( ssl->f_get_timer != NULL &&
ssl->f_get_timer( ssl->p_timer ) == -1 )
{
mbedtls_ssl_set_timer( ssl, ssl->conf->read_timeout );
}
if( ( ret = mbedtls_ssl_read_record( ssl, 1 ) ) != 0 )
{
if( ret == MBEDTLS_ERR_SSL_CONN_EOF )
return( 0 );
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_read_record", ret );
return( ret );
}
if( ssl->in_msglen == 0 &&
ssl->in_msgtype == MBEDTLS_SSL_MSG_APPLICATION_DATA )
{
/*
* OpenSSL sends empty messages to randomize the IV
*/
if( ( ret = mbedtls_ssl_read_record( ssl, 1 ) ) != 0 )
{
if( ret == MBEDTLS_ERR_SSL_CONN_EOF )
return( 0 );
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_read_record", ret );
return( ret );
}
}
if( ssl->in_msgtype == MBEDTLS_SSL_MSG_HANDSHAKE )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "received handshake message" ) );
/*
* - For client-side, expect SERVER_HELLO_REQUEST.
* - For server-side, expect CLIENT_HELLO.
* - Fail (TLS) or silently drop record (DTLS) in other cases.
*/
#if defined(MBEDTLS_SSL_CLI_C)
if( ssl->conf->endpoint == MBEDTLS_SSL_IS_CLIENT &&
( ssl->in_msg[0] != MBEDTLS_SSL_HS_HELLO_REQUEST ||
ssl->in_hslen != mbedtls_ssl_hs_hdr_len( ssl ) ) )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "handshake received (not HelloRequest)" ) );
/* With DTLS, drop the packet (probably from last handshake) */
#if defined(MBEDTLS_SSL_PROTO_DTLS)
if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
{
continue;
}
#endif
return( MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE );
}
#endif /* MBEDTLS_SSL_CLI_C */
#if defined(MBEDTLS_SSL_SRV_C)
if( ssl->conf->endpoint == MBEDTLS_SSL_IS_SERVER &&
ssl->in_msg[0] != MBEDTLS_SSL_HS_CLIENT_HELLO )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "handshake received (not ClientHello)" ) );
/* With DTLS, drop the packet (probably from last handshake) */
#if defined(MBEDTLS_SSL_PROTO_DTLS)
if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
{
continue;
}
#endif
return( MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE );
}
#endif /* MBEDTLS_SSL_SRV_C */
#if defined(MBEDTLS_SSL_RENEGOTIATION)
/* Determine whether renegotiation attempt should be accepted */
if( ! ( ssl->conf->disable_renegotiation == MBEDTLS_SSL_RENEGOTIATION_DISABLED ||
( ssl->secure_renegotiation == MBEDTLS_SSL_LEGACY_RENEGOTIATION &&
ssl->conf->allow_legacy_renegotiation ==
MBEDTLS_SSL_LEGACY_NO_RENEGOTIATION ) ) )
{
/*
* Accept renegotiation request
*/
/* DTLS clients need to know renego is server-initiated */
#if defined(MBEDTLS_SSL_PROTO_DTLS)
if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM &&
ssl->conf->endpoint == MBEDTLS_SSL_IS_CLIENT )
{
ssl->renego_status = MBEDTLS_SSL_RENEGOTIATION_PENDING;
}
#endif
ret = mbedtls_ssl_start_renegotiation( ssl );
if( ret != MBEDTLS_ERR_SSL_WAITING_SERVER_HELLO_RENEGO &&
ret != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_start_renegotiation",
ret );
return( ret );
}
}
else
#endif /* MBEDTLS_SSL_RENEGOTIATION */
{
/*
* Refuse renegotiation
*/
MBEDTLS_SSL_DEBUG_MSG( 3, ( "refusing renegotiation, sending alert" ) );
#if defined(MBEDTLS_SSL_PROTO_TLS1) || defined(MBEDTLS_SSL_PROTO_TLS1_1) || \
defined(MBEDTLS_SSL_PROTO_TLS1_2)
if( ssl->minor_ver >= MBEDTLS_SSL_MINOR_VERSION_1 )
{
if( ( ret = mbedtls_ssl_send_alert_message( ssl,
MBEDTLS_SSL_ALERT_LEVEL_WARNING,
MBEDTLS_SSL_ALERT_MSG_NO_RENEGOTIATION ) ) != 0 )
{
return( ret );
}
}
else
#endif /* MBEDTLS_SSL_PROTO_TLS1 || MBEDTLS_SSL_PROTO_TLS1_1 ||
MBEDTLS_SSL_PROTO_TLS1_2 */
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
}
}
/* At this point, we don't know whether the renegotiation has been
* completed or not. The cases to consider are the following:
* 1) The renegotiation is complete. In this case, no new record
* has been read yet.
* 2) The renegotiation is incomplete because the client received
* an application data record while awaiting the ServerHello.
* 3) The renegotiation is incomplete because the client received
* a non-handshake, non-application data message while awaiting
* the ServerHello.
* In each of these case, looping will be the proper action:
* - For 1), the next iteration will read a new record and check
* if it's application data.
* - For 2), the loop condition isn't satisfied as application data
* is present, hence continue is the same as break
* - For 3), the loop condition is satisfied and read_record
* will re-deliver the message that was held back by the client
* when expecting the ServerHello.
*/
continue;
}
#if defined(MBEDTLS_SSL_RENEGOTIATION)
else if( ssl->renego_status == MBEDTLS_SSL_RENEGOTIATION_PENDING )
{
if( ssl->conf->renego_max_records >= 0 )
{
if( ++ssl->renego_records_seen > ssl->conf->renego_max_records )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "renegotiation requested, "
"but not honored by client" ) );
return( MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE );
}
}
}
#endif /* MBEDTLS_SSL_RENEGOTIATION */
/* Fatal and closure alerts handled by mbedtls_ssl_read_record() */
if( ssl->in_msgtype == MBEDTLS_SSL_MSG_ALERT )
{
MBEDTLS_SSL_DEBUG_MSG( 2, ( "ignoring non-fatal non-closure alert" ) );
return( MBEDTLS_ERR_SSL_WANT_READ );
}
if( ssl->in_msgtype != MBEDTLS_SSL_MSG_APPLICATION_DATA )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "bad application data message" ) );
return( MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE );
}
ssl->in_offt = ssl->in_msg;
/* We're going to return something now, cancel timer,
* except if handshake (renegotiation) is in progress */
if( ssl->state == MBEDTLS_SSL_HANDSHAKE_OVER )
mbedtls_ssl_set_timer( ssl, 0 );
#if defined(MBEDTLS_SSL_PROTO_DTLS)
/* If we requested renego but received AppData, resend HelloRequest.
* Do it now, after setting in_offt, to avoid taking this branch
* again if ssl_write_hello_request() returns WANT_WRITE */
#if defined(MBEDTLS_SSL_SRV_C) && defined(MBEDTLS_SSL_RENEGOTIATION)
if( ssl->conf->endpoint == MBEDTLS_SSL_IS_SERVER &&
ssl->renego_status == MBEDTLS_SSL_RENEGOTIATION_PENDING )
{
if( ( ret = mbedtls_ssl_resend_hello_request( ssl ) ) != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_resend_hello_request",
ret );
return( ret );
}
}
#endif /* MBEDTLS_SSL_SRV_C && MBEDTLS_SSL_RENEGOTIATION */
#endif /* MBEDTLS_SSL_PROTO_DTLS */
}
n = ( len < ssl->in_msglen )
? len : ssl->in_msglen;
memcpy( buf, ssl->in_offt, n );
ssl->in_msglen -= n;
/* Zeroising the plaintext buffer to erase unused application data
from the memory. */
mbedtls_platform_zeroize( ssl->in_offt, n );
if( ssl->in_msglen == 0 )
{
/* all bytes consumed */
ssl->in_offt = NULL;
ssl->keep_current_message = 0;
}
else
{
/* more data available */
ssl->in_offt += n;
}
MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= read" ) );
return( (int) n );
}
/*
* Send application data to be encrypted by the SSL layer, taking care of max
* fragment length and buffer size.
*
* According to RFC 5246 Section 6.2.1:
*
* Zero-length fragments of Application data MAY be sent as they are
* potentially useful as a traffic analysis countermeasure.
*
* Therefore, it is possible that the input message length is 0 and the
* corresponding return code is 0 on success.
*/
static int ssl_write_real( mbedtls_ssl_context *ssl,
const unsigned char *buf, size_t len )
{
int ret = mbedtls_ssl_get_max_out_record_payload( ssl );
const size_t max_len = (size_t) ret;
if( ret < 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_get_max_out_record_payload", ret );
return( ret );
}
if( len > max_len )
{
#if defined(MBEDTLS_SSL_PROTO_DTLS)
if( ssl->conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "fragment larger than the (negotiated) "
"maximum fragment length: %" MBEDTLS_PRINTF_SIZET
" > %" MBEDTLS_PRINTF_SIZET,
len, max_len ) );
return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
}
else
#endif
len = max_len;
}
if( ssl->out_left != 0 )
{
/*
* The user has previously tried to send the data and
* MBEDTLS_ERR_SSL_WANT_WRITE or the message was only partially
* written. In this case, we expect the high-level write function
* (e.g. mbedtls_ssl_write()) to be called with the same parameters
*/
if( ( ret = mbedtls_ssl_flush_output( ssl ) ) != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_flush_output", ret );
return( ret );
}
}
else
{
/*
* The user is trying to send a message the first time, so we need to
* copy the data into the internal buffers and setup the data structure
* to keep track of partial writes
*/
ssl->out_msglen = len;
ssl->out_msgtype = MBEDTLS_SSL_MSG_APPLICATION_DATA;
memcpy( ssl->out_msg, buf, len );
if( ( ret = mbedtls_ssl_write_record( ssl, SSL_FORCE_FLUSH ) ) != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_write_record", ret );
return( ret );
}
}
return( (int) len );
}
/*
* Write application data, doing 1/n-1 splitting if necessary.
*
* With non-blocking I/O, ssl_write_real() may return WANT_WRITE,
* then the caller will call us again with the same arguments, so
* remember whether we already did the split or not.
*/
#if defined(MBEDTLS_SSL_CBC_RECORD_SPLITTING)
static int ssl_write_split( mbedtls_ssl_context *ssl,
const unsigned char *buf, size_t len )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
if( ssl->conf->cbc_record_splitting ==
MBEDTLS_SSL_CBC_RECORD_SPLITTING_DISABLED ||
len <= 1 ||
ssl->minor_ver > MBEDTLS_SSL_MINOR_VERSION_1 ||
mbedtls_cipher_get_cipher_mode( &ssl->transform_out->cipher_ctx_enc )
!= MBEDTLS_MODE_CBC )
{
return( ssl_write_real( ssl, buf, len ) );
}
if( ssl->split_done == 0 )
{
if( ( ret = ssl_write_real( ssl, buf, 1 ) ) <= 0 )
return( ret );
ssl->split_done = 1;
}
if( ( ret = ssl_write_real( ssl, buf + 1, len - 1 ) ) <= 0 )
return( ret );
ssl->split_done = 0;
return( ret + 1 );
}
#endif /* MBEDTLS_SSL_CBC_RECORD_SPLITTING */
/*
* Write application data (public-facing wrapper)
*/
int mbedtls_ssl_write( mbedtls_ssl_context *ssl, const unsigned char *buf, size_t len )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write" ) );
if( ssl == NULL || ssl->conf == NULL )
return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
#if defined(MBEDTLS_SSL_RENEGOTIATION)
if( ( ret = ssl_check_ctr_renegotiate( ssl ) ) != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "ssl_check_ctr_renegotiate", ret );
return( ret );
}
#endif
if( ssl->state != MBEDTLS_SSL_HANDSHAKE_OVER )
{
if( ( ret = mbedtls_ssl_handshake( ssl ) ) != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_handshake", ret );
return( ret );
}
}
#if defined(MBEDTLS_SSL_CBC_RECORD_SPLITTING)
ret = ssl_write_split( ssl, buf, len );
#else
ret = ssl_write_real( ssl, buf, len );
#endif
MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= write" ) );
return( ret );
}
/*
* Notify the peer that the connection is being closed
*/
int mbedtls_ssl_close_notify( mbedtls_ssl_context *ssl )
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
if( ssl == NULL || ssl->conf == NULL )
return( MBEDTLS_ERR_SSL_BAD_INPUT_DATA );
MBEDTLS_SSL_DEBUG_MSG( 2, ( "=> write close notify" ) );
if( ssl->out_left != 0 )
return( mbedtls_ssl_flush_output( ssl ) );
if( ssl->state == MBEDTLS_SSL_HANDSHAKE_OVER )
{
if( ( ret = mbedtls_ssl_send_alert_message( ssl,
MBEDTLS_SSL_ALERT_LEVEL_WARNING,
MBEDTLS_SSL_ALERT_MSG_CLOSE_NOTIFY ) ) != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_send_alert_message", ret );
return( ret );
}
}
MBEDTLS_SSL_DEBUG_MSG( 2, ( "<= write close notify" ) );
return( 0 );
}
void mbedtls_ssl_transform_free( mbedtls_ssl_transform *transform )
{
if( transform == NULL )
return;
mbedtls_cipher_free( &transform->cipher_ctx_enc );
mbedtls_cipher_free( &transform->cipher_ctx_dec );
#if defined(MBEDTLS_SSL_SOME_MODES_USE_MAC)
mbedtls_md_free( &transform->md_ctx_enc );
mbedtls_md_free( &transform->md_ctx_dec );
#endif
mbedtls_platform_zeroize( transform, sizeof( mbedtls_ssl_transform ) );
}
#if defined(MBEDTLS_SSL_PROTO_DTLS)
void mbedtls_ssl_buffering_free( mbedtls_ssl_context *ssl )
{
unsigned offset;
mbedtls_ssl_handshake_params * const hs = ssl->handshake;
if( hs == NULL )
return;
ssl_free_buffered_record( ssl );
for( offset = 0; offset < MBEDTLS_SSL_MAX_BUFFERED_HS; offset++ )
ssl_buffering_free_slot( ssl, offset );
}
static void ssl_buffering_free_slot( mbedtls_ssl_context *ssl,
uint8_t slot )
{
mbedtls_ssl_handshake_params * const hs = ssl->handshake;
mbedtls_ssl_hs_buffer * const hs_buf = &hs->buffering.hs[slot];
if( slot >= MBEDTLS_SSL_MAX_BUFFERED_HS )
return;
if( hs_buf->is_valid == 1 )
{
hs->buffering.total_bytes_buffered -= hs_buf->data_len;
mbedtls_platform_zeroize( hs_buf->data, hs_buf->data_len );
mbedtls_free( hs_buf->data );
memset( hs_buf, 0, sizeof( mbedtls_ssl_hs_buffer ) );
}
}
#endif /* MBEDTLS_SSL_PROTO_DTLS */
/*
* Convert version numbers to/from wire format
* and, for DTLS, to/from TLS equivalent.
*
* For TLS this is the identity.
* For DTLS, use 1's complement (v -> 255 - v, and then map as follows:
* 1.0 <-> 3.2 (DTLS 1.0 is based on TLS 1.1)
* 1.x <-> 3.x+1 for x != 0 (DTLS 1.2 based on TLS 1.2)
*/
void mbedtls_ssl_write_version( int major, int minor, int transport,
unsigned char ver[2] )
{
#if defined(MBEDTLS_SSL_PROTO_DTLS)
if( transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
{
if( minor == MBEDTLS_SSL_MINOR_VERSION_2 )
--minor; /* DTLS 1.0 stored as TLS 1.1 internally */
ver[0] = (unsigned char)( 255 - ( major - 2 ) );
ver[1] = (unsigned char)( 255 - ( minor - 1 ) );
}
else
#else
((void) transport);
#endif
{
ver[0] = (unsigned char) major;
ver[1] = (unsigned char) minor;
}
}
void mbedtls_ssl_read_version( int *major, int *minor, int transport,
const unsigned char ver[2] )
{
#if defined(MBEDTLS_SSL_PROTO_DTLS)
if( transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM )
{
*major = 255 - ver[0] + 2;
*minor = 255 - ver[1] + 1;
if( *minor == MBEDTLS_SSL_MINOR_VERSION_1 )
++*minor; /* DTLS 1.0 stored as TLS 1.1 internally */
}
else
#else
((void) transport);
#endif
{
*major = ver[0];
*minor = ver[1];
}
}
#endif /* MBEDTLS_SSL_TLS_C */