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ssl_msg.c
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/*
* 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 "constant_time_internal.h"
#include "mbedtls/constant_time.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 );
}
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
* there doesn't seem to be a usecase for it.
*/
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 );
}
#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)
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 */
/* `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,
size_t taglen )
{
/* 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.
* Moreover, the additional data involves the length of the TLS
* ciphertext, not the TLS plaintext as in earlier versions.
* Quoting RFC 8446 (TLS 1.3):
*
* additional_data = TLSCiphertext.opaque_type ||
* TLSCiphertext.legacy_record_version ||
* TLSCiphertext.length
*
* We pass the tag length to this function in order to compute the
* ciphertext length from the inner plaintext length rec->data_len via
*
* TLSCiphertext.length = TLSInnerPlaintext.length + taglen.
*
*/
unsigned char *cur = add_data;
size_t ad_len_field = rec->data_len;
#if defined(MBEDTLS_SSL_PROTO_TLS1_3)
if( minor_ver == MBEDTLS_SSL_MINOR_VERSION_4 )
{
/* In TLS 1.3, the AAD contains the length of the TLSCiphertext,
* which differs from the length of the TLSInnerPlaintext
* by the length of the authentication tag. */
ad_len_field += taglen;
}
else
#endif /* MBEDTLS_SSL_PROTO_TLS1_3 */
{
((void) minor_ver);
((void) taglen);
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++;
MBEDTLS_PUT_UINT16_BE( ad_len_field, cur, 0 );
cur += 2;
}
else
#endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
{
MBEDTLS_PUT_UINT16_BE( ad_len_field, cur, 0 );
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 )
{
#if !defined(MBEDTLS_USE_PSA_CRYPTO)
mbedtls_cipher_mode_t mode;
#endif /* MBEDTLS_USE_PSA_CRYPTO */
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 1.2. */
#if !( defined(MBEDTLS_SSL_SOME_SUITES_USE_CBC) && \
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 );
#if !defined(MBEDTLS_USE_PSA_CRYPTO)
mode = mbedtls_cipher_get_cipher_mode( &transform->cipher_ctx_enc );
#endif /* MBEDTLS_USE_PSA_CRYPTO */
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)
if( transform->minor_ver == MBEDTLS_SSL_MINOR_VERSION_4 )
{
size_t padding =
ssl_compute_padding_length( rec->data_len,
MBEDTLS_SSL_CID_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 */
#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_TLS1_3_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_SUITES_USE_MAC)
#if defined(MBEDTLS_USE_PSA_CRYPTO)
if ( transform->psa_alg == MBEDTLS_SSL_NULL_CIPHER ||
( transform->psa_alg == PSA_ALG_CBC_NO_PADDING
#else
if( mode == MBEDTLS_MODE_STREAM ||
( mode == MBEDTLS_MODE_CBC
#endif
#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_2)
unsigned char mac[MBEDTLS_SSL_MAC_ADD];
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
ssl_extract_add_data_from_record( add_data, &add_data_len, rec,
transform->minor_ver,
transform->taglen );
ret = mbedtls_md_hmac_update( &transform->md_ctx_enc, add_data,
add_data_len );
if( ret != 0 )
goto hmac_failed_etm_disabled;
ret = mbedtls_md_hmac_update( &transform->md_ctx_enc, data, rec->data_len );
if( ret != 0 )
goto hmac_failed_etm_disabled;
ret = mbedtls_md_hmac_finish( &transform->md_ctx_enc, mac );
if( ret != 0 )
goto hmac_failed_etm_disabled;
ret = mbedtls_md_hmac_reset( &transform->md_ctx_enc );
if( ret != 0 )
goto hmac_failed_etm_disabled;
memcpy( data + rec->data_len, mac, transform->maclen );
#endif
MBEDTLS_SSL_DEBUG_BUF( 4, "computed mac", data + rec->data_len,
transform->maclen );
rec->data_len += transform->maclen;
post_avail -= transform->maclen;
auth_done++;
hmac_failed_etm_disabled:
mbedtls_platform_zeroize( mac, transform->maclen );
if( ret != 0 )
{
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_md_hmac_xxx", ret );
return( ret );
}
}
#endif /* MBEDTLS_SSL_SOME_SUITES_USE_MAC */
/*
* Encrypt
*/
#if defined(MBEDTLS_SSL_SOME_SUITES_USE_STREAM)
#if defined(MBEDTLS_USE_PSA_CRYPTO)
if ( transform->psa_alg == MBEDTLS_SSL_NULL_CIPHER )
#else
if( mode == MBEDTLS_MODE_STREAM )
#endif
{
MBEDTLS_SSL_DEBUG_MSG( 3, ( "before encrypt: msglen = %" MBEDTLS_PRINTF_SIZET ", "
"including %d bytes of padding",
rec->data_len, 0 ) );
/* The only supported stream cipher is "NULL",
* so there's nothing to do here.*/
}
else
#endif /* MBEDTLS_SSL_SOME_SUITES_USE_STREAM */
#if defined(MBEDTLS_GCM_C) || \
defined(MBEDTLS_CCM_C) || \
defined(MBEDTLS_CHACHAPOLY_C)
#if defined(MBEDTLS_USE_PSA_CRYPTO)
if ( PSA_ALG_IS_AEAD( transform->psa_alg ) )
#else
if( mode == MBEDTLS_MODE_GCM ||
mode == MBEDTLS_MODE_CCM ||
mode == MBEDTLS_MODE_CHACHAPOLY )
#endif /* MBEDTLS_USE_PSA_CRYPTO */
{
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 );
#if defined(MBEDTLS_USE_PSA_CRYPTO)
psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
#endif /* MBEDTLS_USE_PSA_CRYPTO */
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
/* 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,
transform->taglen );
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 defined(MBEDTLS_USE_PSA_CRYPTO)
status = psa_aead_encrypt( transform->psa_key_enc,
transform->psa_alg,
iv, transform->ivlen,
add_data, add_data_len,
data, rec->data_len,
data, rec->buf_len - (data - rec->buf),
&rec->data_len );
if( status != PSA_SUCCESS )
{
ret = psa_ssl_status_to_mbedtls( status );
MBEDTLS_SSL_DEBUG_RET( 1, "mbedtls_ssl_encrypt_buf", ret );
return( ret );
}
#else
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_ext", ret );
return( ret );
}
#endif /* MBEDTLS_USE_PSA_CRYPTO */
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 defined(MBEDTLS_USE_PSA_CRYPTO)
if ( transform->psa_alg == PSA_ALG_CBC_NO_PADDING )
#else
if( mode == MBEDTLS_MODE_CBC )
#endif /* MBEDTLS_USE_PSA_CRYPTO */
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
size_t padlen, i;
size_t olen;
#if defined(MBEDTLS_USE_PSA_CRYPTO)
psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
size_t part_len;
psa_cipher_operation_t cipher_op = PSA_CIPHER_OPERATION_INIT;
#endif /* MBEDTLS_USE_PSA_CRYPTO */
/* 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_2)
/*
* Prepend per-record IV for block cipher in TLS v1.2 as per
* Method 1 (6.2.3.2. in RFC4346 and RFC5246)
*/
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_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 defined(MBEDTLS_USE_PSA_CRYPTO)
status = psa_cipher_encrypt_setup( &cipher_op,
transform->psa_key_enc, transform->psa_alg );
if( status != PSA_SUCCESS )
{
ret = psa_ssl_status_to_mbedtls( status );
MBEDTLS_SSL_DEBUG_RET( 1, "psa_cipher_encrypt_setup", ret );
return( ret );
}
status = psa_cipher_set_iv( &cipher_op, transform->iv_enc, transform->ivlen );
if( status != PSA_SUCCESS )
{
ret = psa_ssl_status_to_mbedtls( status );
MBEDTLS_SSL_DEBUG_RET( 1, "psa_cipher_set_iv", ret );
return( ret );
}
status = psa_cipher_update( &cipher_op,
data, rec->data_len,
data, rec->data_len, &olen );
if( status != PSA_SUCCESS )
{
ret = psa_ssl_status_to_mbedtls( status );
MBEDTLS_SSL_DEBUG_RET( 1, "psa_cipher_update", ret );
return( ret );
}
status = psa_cipher_finish( &cipher_op,
data + olen, rec->data_len - olen,
&part_len );
if( status != PSA_SUCCESS )
{
ret = psa_ssl_status_to_mbedtls( status );
MBEDTLS_SSL_DEBUG_RET( 1, "psa_cipher_finish", ret );
return( ret );
}
olen += part_len;
#else
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 );
}
#endif /* MBEDTLS_USE_PSA_CRYPTO */
if( rec->data_len != olen )
{
MBEDTLS_SSL_DEBUG_MSG( 1, ( "should never happen" ) );
return( MBEDTLS_ERR_SSL_INTERNAL_ERROR );
}
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];