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review.trustedfirmware.org / mirror / mbed-tls.git / refs/heads/master / . / library / 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 OR GPL-2.0-or-later
*/
/*
* http://www.ietf.org/rfc/rfc2246.txt
* http://www.ietf.org/rfc/rfc4346.txt
*/
#include "common.h"
#if defined(MBEDTLS_SSL_TLS_C)
#include "mbedtls/platform.h"
#include "mbedtls/ssl.h"
#include "ssl_misc.h"
#include "debug_internal.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 "psa_util_internal.h"
#include "psa/crypto.h"
#endif
#if defined(MBEDTLS_X509_CRT_PARSE_C)
#include "mbedtls/oid.h"
#endif
#if defined(MBEDTLS_USE_PSA_CRYPTO)
/* Define a local translating function to save code size by not using too many
* arguments in each translating place. */
static int local_err_translation(psa_status_t status)
{
return psa_status_to_mbedtls(status, psa_to_ssl_errors,
ARRAY_LENGTH(psa_to_ssl_errors),
psa_generic_status_to_mbedtls);
}
#define PSA_TO_MBEDTLS_ERR(status) local_err_translation(status)
#endif
#if defined(MBEDTLS_SSL_SOME_SUITES_USE_MAC)
#if defined(MBEDTLS_USE_PSA_CRYPTO)
#if defined(PSA_WANT_ALG_SHA_384)
#define MAX_HASH_BLOCK_LENGTH PSA_HASH_BLOCK_LENGTH(PSA_ALG_SHA_384)
#elif defined(PSA_WANT_ALG_SHA_256)
#define MAX_HASH_BLOCK_LENGTH PSA_HASH_BLOCK_LENGTH(PSA_ALG_SHA_256)
#else /* See check_config.h */
#define MAX_HASH_BLOCK_LENGTH PSA_HASH_BLOCK_LENGTH(PSA_ALG_SHA_1)
#endif
MBEDTLS_STATIC_TESTABLE
int mbedtls_ct_hmac(mbedtls_svc_key_id_t key,
psa_algorithm_t mac_alg,
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 psa_hash_clone()
* extension 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).
*
* We'll first compute ikey/okey, then 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.
*/
psa_algorithm_t hash_alg = PSA_ALG_HMAC_GET_HASH(mac_alg);
const size_t block_size = PSA_HASH_BLOCK_LENGTH(hash_alg);
unsigned char key_buf[MAX_HASH_BLOCK_LENGTH];
const size_t hash_size = PSA_HASH_LENGTH(hash_alg);
psa_hash_operation_t operation = PSA_HASH_OPERATION_INIT;
size_t hash_length;
unsigned char aux_out[PSA_HASH_MAX_SIZE];
psa_hash_operation_t aux_operation = PSA_HASH_OPERATION_INIT;
size_t offset;
psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
size_t mac_key_length;
size_t i;
#define PSA_CHK(func_call) \
do { \
status = (func_call); \
if (status != PSA_SUCCESS) \
goto cleanup; \
} while (0)
/* Export MAC key
* We assume key length is always exactly the output size
* which is never more than the block size, thus we use block_size
* as the key buffer size.
*/
PSA_CHK(psa_export_key(key, key_buf, block_size, &mac_key_length));
/* Calculate ikey */
for (i = 0; i < mac_key_length; i++) {
key_buf[i] = (unsigned char) (key_buf[i] ^ 0x36);
}
for (; i < block_size; ++i) {
key_buf[i] = 0x36;
}
PSA_CHK(psa_hash_setup(&operation, hash_alg));
/* Now compute inner_hash = HASH(ikey + msg) */
PSA_CHK(psa_hash_update(&operation, key_buf, block_size));
PSA_CHK(psa_hash_update(&operation, add_data, add_data_len));
PSA_CHK(psa_hash_update(&operation, data, min_data_len));
/* Fill the hash buffer in advance with something that is
* not a valid hash (barring an attack on the hash and
* deliberately-crafted input), in case the caller doesn't
* check the return status properly. */
memset(output, '!', hash_size);
/* For each possible length, compute the hash up to that point */
for (offset = min_data_len; offset <= max_data_len; offset++) {
PSA_CHK(psa_hash_clone(&operation, &aux_operation));
PSA_CHK(psa_hash_finish(&aux_operation, aux_out,
PSA_HASH_MAX_SIZE, &hash_length));
/* Keep only the correct inner_hash in the output buffer */
mbedtls_ct_memcpy_if(mbedtls_ct_uint_eq(offset, data_len_secret),
output, aux_out, NULL, hash_size);
if (offset < max_data_len) {
PSA_CHK(psa_hash_update(&operation, data + offset, 1));
}
}
/* Abort current operation to prepare for final operation */
PSA_CHK(psa_hash_abort(&operation));
/* Calculate okey */
for (i = 0; i < mac_key_length; i++) {
key_buf[i] = (unsigned char) ((key_buf[i] ^ 0x36) ^ 0x5C);
}
for (; i < block_size; ++i) {
key_buf[i] = 0x5C;
}
/* Now compute HASH(okey + inner_hash) */
PSA_CHK(psa_hash_setup(&operation, hash_alg));
PSA_CHK(psa_hash_update(&operation, key_buf, block_size));
PSA_CHK(psa_hash_update(&operation, output, hash_size));
PSA_CHK(psa_hash_finish(&operation, output, hash_size, &hash_length));
#undef PSA_CHK
cleanup:
mbedtls_platform_zeroize(key_buf, MAX_HASH_BLOCK_LENGTH);
mbedtls_platform_zeroize(aux_out, PSA_HASH_MAX_SIZE);
psa_hash_abort(&operation);
psa_hash_abort(&aux_operation);
return PSA_TO_MBEDTLS_ERR(status);
}
#undef MAX_HASH_BLOCK_LENGTH
#else
MBEDTLS_STATIC_TESTABLE
int mbedtls_ct_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 1.2 only supports 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));
/* Fill the hash buffer in advance with something that is
* not a valid hash (barring an attack on the hash and
* deliberately-crafted input), in case the caller doesn't
* check the return status properly. */
memset(output, '!', hash_size);
/* 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_ct_memcpy_if(mbedtls_ct_uint_eq(offset, data_len_secret),
output, aux_out, NULL, hash_size);
if (offset < max_data_len) {
MD_CHK(mbedtls_md_update(ctx, data + offset, 1));
}
}
/* The context needs to finish() before it starts() again */
MD_CHK(mbedtls_md_finish(ctx, aux_out));
/* 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;
}
#endif /* MBEDTLS_USE_PSA_CRYPTO */
#endif /* MBEDTLS_SSL_SOME_SUITES_USE_MAC */
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;
}
MBEDTLS_CHECK_RETURN_CRITICAL
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);
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_load_buffered_message(mbedtls_ssl_context *ssl);
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_load_buffered_record(mbedtls_ssl_context *ssl);
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_buffer_message(mbedtls_ssl_context *ssl);
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_buffer_future_record(mbedtls_ssl_context *ssl,
mbedtls_record const *rec);
MBEDTLS_CHECK_RETURN_CRITICAL
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;
}
MBEDTLS_CHECK_RETURN_CRITICAL
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);
}
MBEDTLS_CHECK_RETURN_CRITICAL
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.
*/
MBEDTLS_CHECK_RETURN_CRITICAL
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.
*/
MBEDTLS_CHECK_RETURN_CRITICAL
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. */
MBEDTLS_CHECK_RETURN_CRITICAL
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 */
/* The size of the `add_data` structure depends on various
* factors, namely
*
* 1) CID functionality disabled
*
* additional_data =
* 8: seq_num +
* 1: type +
* 2: version +
* 2: length of inner plaintext +
*
* size = 13 bytes
*
* 2) CID functionality based on RFC 9146 enabled
*
* size = 8 + 1 + 1 + 1 + 2 + 2 + 6 + 2 + CID-length
* = 23 + CID-length
*
* 3) CID functionality based on legacy CID version
according to draft-ietf-tls-dtls-connection-id-05
* https://tools.ietf.org/html/draft-ietf-tls-dtls-connection-id-05
*
* size = 13 + 1 + CID-length
*
* More information about the CID usage:
*
* Per Section 5.3 of draft-ietf-tls-dtls-connection-id-05 the
* size of the additional data structure is calculated as:
*
* additional_data =
* 8: seq_num +
* 1: tls12_cid +
* 2: DTLSCipherText.version +
* n: cid +
* 1: cid_length +
* 2: length_of_DTLSInnerPlaintext
*
* Per RFC 9146 the size of the add_data structure is calculated as:
*
* additional_data =
* 8: seq_num_placeholder +
* 1: tls12_cid +
* 1: cid_length +
* 1: tls12_cid +
* 2: DTLSCiphertext.version +
* 2: epoch +
* 6: sequence_number +
* n: cid +
* 2: length_of_DTLSInnerPlaintext
*
*/
static void ssl_extract_add_data_from_record(unsigned char *add_data,
size_t *add_data_len,
mbedtls_record *rec,
mbedtls_ssl_protocol_version
tls_version,
size_t taglen)
{
/* Several types of ciphers have been defined for use with TLS and DTLS,
* and the MAC calculations for those ciphers differ slightly. Further
* variants were added when the CID functionality was added with RFC 9146.
* This implementations also considers the use of a legacy version of the
* CID specification published in draft-ietf-tls-dtls-connection-id-05,
* which is used in deployments.
*
* We will distinguish between the non-CID and the CID cases below.
*
* --- Non-CID cases ---
*
* Quoting RFC 5246 (TLS 1.2):
*
* additional_data = seq_num + TLSCompressed.type +
* TLSCompressed.version + TLSCompressed.length;
*
* 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.
*
* --- CID cases ---
*
* RFC 9146 uses a common pattern when constructing the data
* passed into a MAC / AEAD cipher.
*
* Data concatenation for MACs used with block ciphers with
* Encrypt-then-MAC Processing (with CID):
*
* data = seq_num_placeholder +
* tls12_cid +
* cid_length +
* tls12_cid +
* DTLSCiphertext.version +
* epoch +
* sequence_number +
* cid +
* DTLSCiphertext.length +
* IV +
* ENC(content + padding + padding_length)
*
* Data concatenation for MACs used with block ciphers (with CID):
*
* data = seq_num_placeholder +
* tls12_cid +
* cid_length +
* tls12_cid +
* DTLSCiphertext.version +
* epoch +
* sequence_number +
* cid +
* length_of_DTLSInnerPlaintext +
* DTLSInnerPlaintext.content +
* DTLSInnerPlaintext.real_type +
* DTLSInnerPlaintext.zeros
*
* AEAD ciphers use the following additional data calculation (with CIDs):
*
* additional_data = seq_num_placeholder +
* tls12_cid +
* cid_length +
* tls12_cid +
* DTLSCiphertext.version +
* epoch +
* sequence_number +
* cid +
* length_of_DTLSInnerPlaintext
*
* Section 5.3 of draft-ietf-tls-dtls-connection-id-05 (for legacy CID use)
* defines the additional data calculation as follows:
*
* additional_data = seq_num +
* tls12_cid +
* DTLSCipherText.version +
* cid +
* cid_length +
* length_of_DTLSInnerPlaintext
*/
unsigned char *cur = add_data;
size_t ad_len_field = rec->data_len;
#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) && \
MBEDTLS_SSL_DTLS_CONNECTION_ID_COMPAT == 0
const unsigned char seq_num_placeholder[] = { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
#endif
#if defined(MBEDTLS_SSL_PROTO_TLS1_3)
if (tls_version == MBEDTLS_SSL_VERSION_TLS1_3) {
/* 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) tls_version);
((void) taglen);
#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) && \
MBEDTLS_SSL_DTLS_CONNECTION_ID_COMPAT == 0
if (rec->cid_len != 0) {
// seq_num_placeholder
memcpy(cur, seq_num_placeholder, sizeof(seq_num_placeholder));
cur += sizeof(seq_num_placeholder);
// tls12_cid type
*cur = rec->type;
cur++;
// cid_length
*cur = rec->cid_len;
cur++;
} else
#endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
{
// epoch + sequence number
memcpy(cur, rec->ctr, sizeof(rec->ctr));
cur += sizeof(rec->ctr);
}
}
// type
*cur = rec->type;
cur++;
// version
memcpy(cur, rec->ver, sizeof(rec->ver));
cur += sizeof(rec->ver);
#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) && \
MBEDTLS_SSL_DTLS_CONNECTION_ID_COMPAT == 1
if (rec->cid_len != 0) {
// CID
memcpy(cur, rec->cid, rec->cid_len);
cur += rec->cid_len;
// cid_length
*cur = rec->cid_len;
cur++;
// length of inner plaintext
MBEDTLS_PUT_UINT16_BE(ad_len_field, cur, 0);
cur += 2;
} else
#elif defined(MBEDTLS_SSL_DTLS_CONNECTION_ID) && \
MBEDTLS_SSL_DTLS_CONNECTION_ID_COMPAT == 0
if (rec->cid_len != 0) {
// epoch + sequence number
memcpy(cur, rec->ctr, sizeof(rec->ctr));
cur += sizeof(rec->ctr);
// CID
memcpy(cur, rec->cid, rec->cid_len);
cur += rec->cid_len;
// length of inner plaintext
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 = (size_t) (cur - add_data);
}
#if defined(MBEDTLS_SSL_HAVE_AEAD)
MBEDTLS_CHECK_RETURN_CRITICAL
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)
{
/* 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;
mbedtls_xor(dst_iv, dst_iv, dynamic_iv, dynamic_iv_len);
}
#endif /* MBEDTLS_SSL_HAVE_AEAD */
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_ssl_mode_t ssl_mode;
int auth_done = 0;
unsigned char *data;
/* For an explanation of the additional data length see
* the description of ssl_extract_add_data_from_record().
*/
#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
unsigned char add_data[23 + MBEDTLS_SSL_CID_OUT_LEN_MAX];
#else
unsigned char add_data[13];
#endif
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;
}
ssl_mode = mbedtls_ssl_get_mode_from_transform(transform);
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 (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->tls_version == MBEDTLS_SSL_VERSION_TLS1_3) {
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 (ssl_mode == MBEDTLS_SSL_MODE_STREAM ||
ssl_mode == MBEDTLS_SSL_MODE_CBC) {
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;
#if defined(MBEDTLS_USE_PSA_CRYPTO)
psa_mac_operation_t operation = PSA_MAC_OPERATION_INIT;
psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
size_t sign_mac_length = 0;
#endif /* MBEDTLS_USE_PSA_CRYPTO */
ssl_extract_add_data_from_record(add_data, &add_data_len, rec,
transform->tls_version,
transform->taglen);
#if defined(MBEDTLS_USE_PSA_CRYPTO)
status = psa_mac_sign_setup(&operation, transform->psa_mac_enc,
transform->psa_mac_alg);
if (status != PSA_SUCCESS) {
goto hmac_failed_etm_disabled;
}
status = psa_mac_update(&operation, add_data, add_data_len);
if (status != PSA_SUCCESS) {
goto hmac_failed_etm_disabled;
}
status = psa_mac_update(&operation, data, rec->data_len);
if (status != PSA_SUCCESS) {
goto hmac_failed_etm_disabled;
}
status = psa_mac_sign_finish(&operation, mac, MBEDTLS_SSL_MAC_ADD,
&sign_mac_length);
if (status != PSA_SUCCESS) {
goto hmac_failed_etm_disabled;
}
#else
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;
}
#endif /* MBEDTLS_USE_PSA_CRYPTO */
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 defined(MBEDTLS_USE_PSA_CRYPTO)
ret = PSA_TO_MBEDTLS_ERR(status);
status = psa_mac_abort(&operation);
if (ret == 0 && status != PSA_SUCCESS) {
ret = PSA_TO_MBEDTLS_ERR(status);
}
#endif /* MBEDTLS_USE_PSA_CRYPTO */
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 (ssl_mode == MBEDTLS_SSL_MODE_STREAM) {
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_SSL_HAVE_AEAD)
if (ssl_mode == MBEDTLS_SSL_MODE_AEAD) {
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->tls_version,
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_TO_MBEDTLS_ERR(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 - (size_t) (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_SSL_HAVE_AEAD */
#if defined(MBEDTLS_SSL_SOME_SUITES_USE_CBC)
if (ssl_mode == MBEDTLS_SSL_MODE_CBC ||
ssl_mode == MBEDTLS_SSL_MODE_CBC_ETM) {
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_TO_MBEDTLS_ERR(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_TO_MBEDTLS_ERR(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_TO_MBEDTLS_ERR(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_TO_MBEDTLS_ERR(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];
#if defined(MBEDTLS_USE_PSA_CRYPTO)
psa_mac_operation_t operation = PSA_MAC_OPERATION_INIT;
size_t sign_mac_length = 0;
#endif /* MBEDTLS_USE_PSA_CRYPTO */
/* MAC(MAC_write_key, add_data, IV, 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->tls_version,
transform->taglen);
MBEDTLS_SSL_DEBUG_MSG(3, ("using encrypt then mac"));
MBEDTLS_SSL_DEBUG_BUF(4, "MAC'd meta-data", add_data,
add_data_len);
#if defined(MBEDTLS_USE_PSA_CRYPTO)
status = psa_mac_sign_setup(&operation, transform->psa_mac_enc,
transform->psa_mac_alg);
if (status != PSA_SUCCESS) {
goto hmac_failed_etm_enabled;
}
status = psa_mac_update(&operation, add_data, add_data_len);
if (status != PSA_SUCCESS) {
goto hmac_failed_etm_enabled;
}
status = psa_mac_update(&operation, data, rec->data_len);
if (status != PSA_SUCCESS) {
goto hmac_failed_etm_enabled;
}
status = psa_mac_sign_finish(&operation, mac, MBEDTLS_SSL_MAC_ADD,
&sign_mac_length);
if (status != PSA_SUCCESS) {
goto hmac_failed_etm_enabled;
}
#else
ret = mbedtls_md_hmac_update(&transform->md_ctx_enc, add_data,
add_data_len);
if (ret != 0) {
goto hmac_failed_etm_enabled;
}
ret = mbedtls_md_hmac_update(&transform->md_ctx_enc,
data, rec->data_len);
if (ret != 0) {
goto hmac_failed_etm_enabled;
}
ret = mbedtls_md_hmac_finish(&transform->md_ctx_enc, mac);
if (ret != 0) {
goto hmac_failed_etm_enabled;
}
ret = mbedtls_md_hmac_reset(&transform->md_ctx_enc);
if (ret != 0) {
goto hmac_failed_etm_enabled;
}
#endif /* MBEDTLS_USE_PSA_CRYPTO */
memcpy(data + rec->data_len, mac, transform->maclen);
rec->data_len += transform->maclen;
post_avail -= transform->maclen;
auth_done++;
hmac_failed_etm_enabled:
mbedtls_platform_zeroize(mac, transform->maclen);
#if defined(MBEDTLS_USE_PSA_CRYPTO)
ret = PSA_TO_MBEDTLS_ERR(status);
status = psa_mac_abort(&operation);
if (ret == 0 && status != PSA_SUCCESS) {
ret = PSA_TO_MBEDTLS_ERR(status);
}
#endif /* MBEDTLS_USE_PSA_CRYPTO */
if (ret != 0) {
MBEDTLS_SSL_DEBUG_RET(1, "HMAC calculation failed", ret);
return ret;
}
}
#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;
}
int mbedtls_ssl_decrypt_buf(mbedtls_ssl_context const *ssl,
mbedtls_ssl_transform *transform,
mbedtls_record *rec)
{
#if defined(MBEDTLS_SSL_SOME_SUITES_USE_CBC) || defined(MBEDTLS_SSL_HAVE_AEAD)
size_t olen;
#endif /* MBEDTLS_SSL_SOME_SUITES_USE_CBC || MBEDTLS_SSL_HAVE_AEAD */
mbedtls_ssl_mode_t ssl_mode;
int ret;
int auth_done = 0;
#if defined(MBEDTLS_SSL_SOME_SUITES_USE_MAC)
size_t padlen = 0;
mbedtls_ct_condition_t correct = MBEDTLS_CT_TRUE;
#endif
unsigned char *data;
/* For an explanation of the additional data length see
* the description of ssl_extract_add_data_from_record().
*/
#if defined(MBEDTLS_SSL_DTLS_CONNECTION_ID)
unsigned char add_data[23 + MBEDTLS_SSL_CID_IN_LEN_MAX];
#else
unsigned char add_data[13];
#endif
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;
ssl_mode = mbedtls_ssl_get_mode_from_transform(transform);
#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_SSL_SOME_SUITES_USE_STREAM)
if (ssl_mode == MBEDTLS_SSL_MODE_STREAM) {
if (rec->data_len < transform->maclen) {
MBEDTLS_SSL_DEBUG_MSG(1,
("Record too short for MAC:"
" %" MBEDTLS_PRINTF_SIZET " < %" MBEDTLS_PRINTF_SIZET,
rec->data_len, transform->maclen));
return MBEDTLS_ERR_SSL_INVALID_MAC;
}
/* The only supported stream cipher is "NULL",
* so there's no encryption to do here.*/
} else
#endif /* MBEDTLS_SSL_SOME_SUITES_USE_STREAM */
#if defined(MBEDTLS_SSL_HAVE_AEAD)
if (ssl_mode == MBEDTLS_SSL_MODE_AEAD) {
unsigned char iv[12];
unsigned char *dynamic_iv;
size_t dynamic_iv_len;
#if defined(MBEDTLS_USE_PSA_CRYPTO)
psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
#endif /* MBEDTLS_USE_PSA_CRYPTO */
/*
* 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->tls_version,
transform->taglen);
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 preceding data, and taglen
* bytes following data + data_len. This justifies
* the debug message and the invocation of
* mbedtls_cipher_auth_decrypt_ext() 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 defined(MBEDTLS_USE_PSA_CRYPTO)
status = psa_aead_decrypt(transform->psa_key_dec,
transform->psa_alg,
iv, transform->ivlen,
add_data, add_data_len,
data, rec->data_len + transform->taglen,
data, rec->buf_len - (data - rec->buf),
&olen);
if (status != PSA_SUCCESS) {
ret = PSA_TO_MBEDTLS_ERR(status);
MBEDTLS_SSL_DEBUG_RET(1, "psa_aead_decrypt", ret);
return ret;
}
#else
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 - (size_t) (data - rec->buf), &olen, /* dst */
transform->taglen)) != 0) {
MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_cipher_auth_decrypt_ext", ret);
if (ret == MBEDTLS_ERR_CIPHER_AUTH_FAILED) {
return MBEDTLS_ERR_SSL_INVALID_MAC;
}
return ret;
}
#endif /* MBEDTLS_USE_PSA_CRYPTO */
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_SSL_HAVE_AEAD */
#if defined(MBEDTLS_SSL_SOME_SUITES_USE_CBC)
if (ssl_mode == MBEDTLS_SSL_MODE_CBC ||
ssl_mode == MBEDTLS_SSL_MODE_CBC_ETM) {
size_t minlen = 0;
#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 */
/*
* Check immediate ciphertext sanity
*/
#if defined(MBEDTLS_SSL_PROTO_TLS1_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 (ssl_mode == MBEDTLS_SSL_MODE_CBC_ETM) {
#if defined(MBEDTLS_USE_PSA_CRYPTO)
psa_mac_operation_t operation = PSA_MAC_OPERATION_INIT;
#else
unsigned char mac_expect[MBEDTLS_SSL_MAC_ADD];
#endif /* MBEDTLS_USE_PSA_CRYPTO */
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_ct_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->tls_version,
transform->taglen);
/* Calculate expected MAC. */
MBEDTLS_SSL_DEBUG_BUF(4, "MAC'd meta-data", add_data,
add_data_len);
#if defined(MBEDTLS_USE_PSA_CRYPTO)
status = psa_mac_verify_setup(&operation, transform->psa_mac_dec,
transform->psa_mac_alg);
if (status != PSA_SUCCESS) {
goto hmac_failed_etm_enabled;
}
status = psa_mac_update(&operation, add_data, add_data_len);
if (status != PSA_SUCCESS) {
goto hmac_failed_etm_enabled;
}
status = psa_mac_update(&operation, data, rec->data_len);
if (status != PSA_SUCCESS) {
goto hmac_failed_etm_enabled;
}
/* Compare expected MAC with MAC at the end of the record. */
status = psa_mac_verify_finish(&operation, data + rec->data_len,
transform->maclen);
if (status != PSA_SUCCESS) {
goto hmac_failed_etm_enabled;
}
#else
ret = mbedtls_md_hmac_update(&transform->md_ctx_dec, add_data,
add_data_len);
if (ret != 0) {
goto hmac_failed_etm_enabled;
}
ret = mbedtls_md_hmac_update(&transform->md_ctx_dec,
data, rec->data_len);
if (ret != 0) {
goto hmac_failed_etm_enabled;
}
ret = mbedtls_md_hmac_finish(&transform->md_ctx_dec, mac_expect);
if (ret != 0) {
goto hmac_failed_etm_enabled;
}
ret = mbedtls_md_hmac_reset(&transform->md_ctx_dec);
if (ret != 0) {
goto hmac_failed_etm_enabled;
}
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_ct_memcmp(data + rec->data_len, mac_expect,
transform->maclen) != 0) {
MBEDTLS_SSL_DEBUG_MSG(1, ("message mac does not match"));
ret = MBEDTLS_ERR_SSL_INVALID_MAC;
goto hmac_failed_etm_enabled;
}
#endif /* MBEDTLS_USE_PSA_CRYPTO */
auth_done++;
hmac_failed_etm_enabled:
#if defined(MBEDTLS_USE_PSA_CRYPTO)
ret = PSA_TO_MBEDTLS_ERR(status);
status = psa_mac_abort(&operation);
if (ret == 0 && status != PSA_SUCCESS) {
ret = PSA_TO_MBEDTLS_ERR(status);
}
#else
mbedtls_platform_zeroize(mac_expect, transform->maclen);
#endif /* MBEDTLS_USE_PSA_CRYPTO */
if (ret != 0) {
if (ret != MBEDTLS_ERR_SSL_INVALID_MAC) {
MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_hmac_xxx", ret);
}
return ret;
}
}
#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_2)
/*
* Initialize for prepended IV for block cipher in TLS v1.2
*/
/* 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_2 */
/* We still have data_len % ivlen == 0 and data_len >= ivlen here. */
#if defined(MBEDTLS_USE_PSA_CRYPTO)
status = psa_cipher_decrypt_setup(&cipher_op,
transform->psa_key_dec, transform->psa_alg);
if (status != PSA_SUCCESS) {
ret = PSA_TO_MBEDTLS_ERR(status);
MBEDTLS_SSL_DEBUG_RET(1, "psa_cipher_decrypt_setup", ret);
return ret;
}
status = psa_cipher_set_iv(&cipher_op, transform->iv_dec, transform->ivlen);
if (status != PSA_SUCCESS) {
ret = PSA_TO_MBEDTLS_ERR(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_TO_MBEDTLS_ERR(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_TO_MBEDTLS_ERR(status);
MBEDTLS_SSL_DEBUG_RET(1, "psa_cipher_finish", ret);
return ret;
}
olen += part_len;
#else
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;
}
#endif /* MBEDTLS_USE_PSA_CRYPTO */
/* 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;
}
/* 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 mbedtls_ct_condition_t ge = mbedtls_ct_uint_ge(
rec->data_len,
padlen + 1);
correct = mbedtls_ct_bool_and(ge, correct);
padlen = mbedtls_ct_size_if_else_0(ge, padlen);
} 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 mbedtls_ct_condition_t ge = mbedtls_ct_uint_ge(
rec->data_len,
transform->maclen + padlen + 1);
correct = mbedtls_ct_bool_and(ge, correct);
padlen = mbedtls_ct_size_if_else_0(ge, padlen);
}
padlen++;
/* Regardless of the validity of the padding,
* we have data_len >= padlen here. */
#if 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 mbedtls_ct_condition_t a = mbedtls_ct_uint_ge(idx, padding_idx);
size_t increment = mbedtls_ct_size_if_else_0(a, 1);
const mbedtls_ct_condition_t b = mbedtls_ct_uint_eq(check[idx], padlen - 1);
increment = mbedtls_ct_size_if_else_0(b, increment);
pad_count += increment;
}
correct = mbedtls_ct_bool_and(mbedtls_ct_uint_eq(pad_count, padlen), correct);
#if defined(MBEDTLS_SSL_DEBUG_ALL)
if (padlen > 0 && correct == MBEDTLS_CT_FALSE) {
MBEDTLS_SSL_DEBUG_MSG(1, ("bad padding byte detected"));
}
#endif
padlen = mbedtls_ct_size_if_else_0(correct, padlen);
#endif /* 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_SUITES_USE_MAC)
if (auth_done == 0) {
unsigned char mac_expect[MBEDTLS_SSL_MAC_ADD] = { 0 };
unsigned char mac_peer[MBEDTLS_SSL_MAC_ADD] = { 0 };
/* For CBC+MAC, 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.
*
* For stream ciphers, we checked above that
* data_len >= maclen.
*/
rec->data_len -= transform->maclen;
ssl_extract_add_data_from_record(add_data, &add_data_len, rec,
transform->tls_version,
transform->taglen);
#if 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;
#if defined(MBEDTLS_USE_PSA_CRYPTO)
ret = mbedtls_ct_hmac(transform->psa_mac_dec,
transform->psa_mac_alg,
add_data, add_data_len,
data, rec->data_len, min_len, max_len,
mac_expect);
#else
ret = mbedtls_ct_hmac(&transform->md_ctx_dec,
add_data, add_data_len,
data, rec->data_len, min_len, max_len,
mac_expect);
#endif /* MBEDTLS_USE_PSA_CRYPTO */
if (ret != 0) {
MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ct_hmac", ret);
goto hmac_failed_etm_disabled;
}
mbedtls_ct_memcpy_offset(mac_peer, data,
rec->data_len,
min_len, max_len,
transform->maclen);
#endif /* 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_ct_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 = MBEDTLS_CT_FALSE;
}
auth_done++;
hmac_failed_etm_disabled:
mbedtls_platform_zeroize(mac_peer, transform->maclen);
mbedtls_platform_zeroize(mac_expect, transform->maclen);
if (ret != 0) {
return ret;
}
}
/*
* Finally check the correct flag
*/
if (correct == MBEDTLS_CT_FALSE) {
return MBEDTLS_ERR_SSL_INVALID_MAC;
}
#endif /* MBEDTLS_SSL_SOME_SUITES_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)
if (transform->tls_version == MBEDTLS_SSL_VERSION_TLS1_3) {
/* 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 */
#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() "));
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 - (size_t) (ssl->in_hdr - ssl->in_buf);
if (mbedtls_ssl_is_handshake_over(ssl) == 0) {
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) {
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() "));
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) {
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
*/
MBEDTLS_CHECK_RETURN_CRITICAL
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
*/
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_swap_epochs(mbedtls_ssl_context *ssl)
{
mbedtls_ssl_transform *tmp_transform;
unsigned char tmp_out_ctr[MBEDTLS_SSL_SEQUENCE_NUMBER_LEN];
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, sizeof(tmp_out_ctr));
memcpy(ssl->cur_out_ctr, ssl->handshake->alt_out_ctr,
sizeof(ssl->cur_out_ctr));
memcpy(ssl->handshake->alt_out_ctr, tmp_out_ctr,
sizeof(ssl->handshake->alt_out_ctr));
/* 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);
int 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 = (size_t) (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] = MBEDTLS_BYTE_2(frag_off);
ssl->out_msg[7] = MBEDTLS_BYTE_1(frag_off);
ssl->out_msg[8] = MBEDTLS_BYTE_0(frag_off);
ssl->out_msg[9] = MBEDTLS_BYTE_2(cur_hs_frag_len);
ssl->out_msg[10] = MBEDTLS_BYTE_1(cur_hs_frag_len);
ssl->out_msg[11] = MBEDTLS_BYTE_0(cur_hs_frag_len);
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 (mbedtls_ssl_is_handshake_over(ssl) == 1) {
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
*/
int mbedtls_ssl_start_handshake_msg(mbedtls_ssl_context *ssl, unsigned char hs_type,
unsigned char **buf, size_t *buf_len)
{
/*
* Reserve 4 bytes for handshake header. ( Section 4,RFC 8446 )
* ...
* HandshakeType msg_type;
* uint24 length;
* ...
*/
*buf = ssl->out_msg + 4;
*buf_len = MBEDTLS_SSL_OUT_CONTENT_LEN - 4;
ssl->out_msgtype = MBEDTLS_SSL_MSG_HANDSHAKE;
ssl->out_msg[0] = hs_type;
return 0;
}
/*
* 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_ext(mbedtls_ssl_context *ssl,
int update_checksum,
int force_flush)
{
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] = MBEDTLS_BYTE_2(hs_len);
ssl->out_msg[2] = MBEDTLS_BYTE_1(hs_len);
ssl->out_msg[3] = MBEDTLS_BYTE_0(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) {
MBEDTLS_PUT_UINT16_BE(ssl->handshake->out_msg_seq, ssl->out_msg, 4);
++(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 && update_checksum != 0) {
ret = ssl->handshake->update_checksum(ssl, ssl->out_msg,
ssl->out_msglen);
if (ret != 0) {
MBEDTLS_SSL_DEBUG_RET(1, "update_checksum", ret);
return ret;
}
}
}
/* 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, force_flush)) != 0) {
MBEDTLS_SSL_DEBUG_RET(1, "ssl_write_record", ret);
return ret;
}
}
MBEDTLS_SSL_DEBUG_MSG(2, ("<= write handshake message"));
return 0;
}
int mbedtls_ssl_finish_handshake_msg(mbedtls_ssl_context *ssl,
size_t buf_len, size_t msg_len)
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
size_t msg_with_header_len;
((void) buf_len);
/* Add reserved 4 bytes for handshake header */
msg_with_header_len = msg_len + 4;
ssl->out_msglen = msg_with_header_len;
MBEDTLS_SSL_PROC_CHK(mbedtls_ssl_write_handshake_msg_ext(ssl, 0, 0));
cleanup:
return ret;
}
/*
* 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, int force_flush)
{
int ret, done = 0;
size_t len = ssl->out_msglen;
int 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_protocol_version tls_ver = ssl->tls_version;
#if defined(MBEDTLS_SSL_PROTO_TLS1_3)
/* TLS 1.3 still uses the TLS 1.2 version identifier
* for backwards compatibility. */
if (tls_ver == MBEDTLS_SSL_VERSION_TLS1_3) {
tls_ver = MBEDTLS_SSL_VERSION_TLS1_2;
}
#endif /* MBEDTLS_SSL_PROTO_TLS1_3 */
mbedtls_ssl_write_version(ssl->out_hdr + 1, ssl->conf->transport,
tls_ver);
memcpy(ssl->out_ctr, ssl->cur_out_ctr, MBEDTLS_SSL_SEQUENCE_NUMBER_LEN);
MBEDTLS_PUT_UINT16_BE(len, ssl->out_len, 0);
if (ssl->transform_out != NULL) {
mbedtls_record rec;
rec.buf = ssl->out_iv;
rec.buf_len = out_buf_len - (size_t) (ssl->out_iv - ssl->out_buf);
rec.data_len = ssl->out_msglen;
rec.data_offset = (size_t) (ssl->out_msg - rec.buf);
memcpy(&rec.ctr[0], ssl->out_ctr, sizeof(rec.ctr));
mbedtls_ssl_write_version(rec.ver, ssl->conf->transport, tls_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;
MBEDTLS_PUT_UINT16_BE(rec.data_len, ssl->out_len, 0);
}
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 if 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)
MBEDTLS_CHECK_RETURN_CRITICAL
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 MBEDTLS_GET_UINT24_BE(ssl->in_msg, 9);
}
static uint32_t ssl_get_hs_frag_off(mbedtls_ssl_context const *ssl)
{
return MBEDTLS_GET_UINT24_BE(ssl->in_msg, 6);
}
MBEDTLS_CHECK_RETURN_CRITICAL
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
*/
MBEDTLS_CHECK_RETURN_CRITICAL
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 MBEDTLS_GET_UINT24_BE(ssl->in_msg, 1);
}
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 = MBEDTLS_GET_UINT16_BE(ssl->in_msg, 4);
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 &&
((mbedtls_ssl_is_handshake_over(ssl) == 0 &&
recv_msg_seq != ssl->handshake->in_msg_seq) ||
(mbedtls_ssl_is_handshake_over(ssl) == 1 &&
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;
}
int mbedtls_ssl_update_handshake_status(mbedtls_ssl_context *ssl)
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
mbedtls_ssl_handshake_params * const hs = ssl->handshake;
if (mbedtls_ssl_is_handshake_over(ssl) == 0 && hs != NULL) {
ret = ssl->handshake->update_checksum(ssl, ssl->in_msg, ssl->in_hslen);
if (ret != 0) {
MBEDTLS_SSL_DEBUG_RET(1, "update_checksum", ret);
return ret;
}
}
/* 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
return 0;
}
/*
* 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]);
}
MBEDTLS_CHECK_RETURN_CRITICAL
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)
/*
* 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
*/
MBEDTLS_CHECK_RETURN_CRITICAL
MBEDTLS_STATIC_TESTABLE
int mbedtls_ssl_check_dtls_clihlo_cookie(
mbedtls_ssl_context *ssl,
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, epoch, fragment_offset;
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.
*/
MBEDTLS_SSL_DEBUG_MSG(4, ("check cookie: in_len=%u",
(unsigned) in_len));
MBEDTLS_SSL_DEBUG_BUF(4, "cli_id", cli_id, cli_id_len);
if (in_len < 61) {
MBEDTLS_SSL_DEBUG_MSG(4, ("check cookie: record too short"));
return MBEDTLS_ERR_SSL_DECODE_ERROR;
}
epoch = MBEDTLS_GET_UINT16_BE(in, 3);
fragment_offset = MBEDTLS_GET_UINT24_BE(in, 19);
if (in[0] != MBEDTLS_SSL_MSG_HANDSHAKE || epoch != 0 ||
fragment_offset != 0) {
MBEDTLS_SSL_DEBUG_MSG(4, ("check cookie: not a good ClientHello"));
MBEDTLS_SSL_DEBUG_MSG(4, (" type=%u epoch=%u fragment_offset=%u",
in[0], (unsigned) epoch,
(unsigned) fragment_offset));
return MBEDTLS_ERR_SSL_DECODE_ERROR;
}
sid_len = in[59];
if (59 + 1 + sid_len + 1 > in_len) {
MBEDTLS_SSL_DEBUG_MSG(4, ("check cookie: sid_len=%u > %u",
(unsigned) sid_len,
(unsigned) in_len - 61));
return MBEDTLS_ERR_SSL_DECODE_ERROR;
}
MBEDTLS_SSL_DEBUG_BUF(4, "sid received from network",
in + 60, sid_len);
cookie_len = in[60 + sid_len];
if (59 + 1 + sid_len + 1 + cookie_len > in_len) {
MBEDTLS_SSL_DEBUG_MSG(4, ("check cookie: cookie_len=%u > %u",
(unsigned) cookie_len,
(unsigned) (in_len - sid_len - 61)));
return MBEDTLS_ERR_SSL_DECODE_ERROR;
}
MBEDTLS_SSL_DEBUG_BUF(4, "cookie received from network",
in + sid_len + 61, cookie_len);
if (ssl->conf->f_cookie_check(ssl->conf->p_cookie,
in + sid_len + 61, cookie_len,
cli_id, cli_id_len) == 0) {
MBEDTLS_SSL_DEBUG_MSG(4, ("check cookie: valid"));
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 (ssl->conf->f_cookie_write(ssl->conf->p_cookie,
&p, obuf + buf_len,
cli_id, cli_id_len) != 0) {
return MBEDTLS_ERR_SSL_INTERNAL_ERROR;
}
*olen = (size_t) (p - obuf);
/* Go back and fill length fields */
obuf[27] = (unsigned char) (*olen - 28);
obuf[14] = obuf[22] = MBEDTLS_BYTE_2(*olen - 25);
obuf[15] = obuf[23] = MBEDTLS_BYTE_1(*olen - 25);
obuf[16] = obuf[24] = MBEDTLS_BYTE_0(*olen - 25);
MBEDTLS_PUT_UINT16_BE(*olen - 13, obuf, 11);
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).
*/
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_handle_possible_reconnect(mbedtls_ssl_context *ssl)
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
size_t len = 0;
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 = mbedtls_ssl_check_dtls_clihlo_cookie(
ssl,
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, "mbedtls_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 */
MBEDTLS_CHECK_RETURN_CRITICAL
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.
*/
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_parse_record_header(mbedtls_ssl_context const *ssl,
unsigned char *buf,
size_t len,
mbedtls_record *rec)
{
mbedtls_ssl_protocol_version tls_version;
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 outer_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];
tls_version = (mbedtls_ssl_protocol_version) mbedtls_ssl_read_version(
buf + rec_hdr_version_offset,
ssl->conf->transport);
if (tls_version > ssl->conf->max_tls_version) {
MBEDTLS_SSL_DEBUG_MSG(1, ("TLS version mismatch: got %u, expected max %u",
(unsigned) tls_version,
(unsigned) ssl->conf->max_tls_version));
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 = MBEDTLS_GET_UINT16_BE(buf, rec_hdr_len_offset);
MBEDTLS_SSL_DEBUG_BUF(4, "input record header", buf, rec->data_offset);
MBEDTLS_SSL_DEBUG_MSG(3, ("input record: msgtype = %u, "
"version = [0x%x], msglen = %" MBEDTLS_PRINTF_SIZET,
rec->type, (unsigned) tls_version, 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 = MBEDTLS_GET_UINT16_BE(rec->ctr, 0);
/* 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)
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_check_client_reconnect(mbedtls_ssl_context *ssl)
{
unsigned int rec_epoch = MBEDTLS_GET_UINT16_BE(ssl->in_ctr, 0);
/*
* 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 &&
mbedtls_ssl_is_handshake_over(ssl) == 1 &&
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
*/
MBEDTLS_CHECK_RETURN_CRITICAL
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);
/*
* In TLS 1.3, always treat ChangeCipherSpec records
* as unencrypted. The only thing we do with them is
* check the length and content and ignore them.
*/
#if defined(MBEDTLS_SSL_PROTO_TLS1_3)
if (ssl->transform_in != NULL &&
ssl->transform_in->tls_version == MBEDTLS_SSL_VERSION_TLS1_3) {
if (rec->type == MBEDTLS_SSL_MSG_CHANGE_CIPHER_SPEC) {
done = 1;
}
}
#endif /* MBEDTLS_SSL_PROTO_TLS1_3 */
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_EARLY_DATA) && defined(MBEDTLS_SSL_SRV_C)
/*
* Although the server rejected early data, it might receive early
* data as long as it has not received the client Finished message.
* It is encrypted with early keys and should be ignored as stated
* in section 4.2.10 of RFC 8446:
*
* "Ignore the extension and return a regular 1-RTT response. The
* server then skips past early data by attempting to deprotect
* received records using the handshake traffic key, discarding
* records which fail deprotection (up to the configured
* max_early_data_size). Once a record is deprotected successfully,
* it is treated as the start of the client's second flight and the
* server proceeds as with an ordinary 1-RTT handshake."
*/
if ((old_msg_type == MBEDTLS_SSL_MSG_APPLICATION_DATA) &&
(ssl->discard_early_data_record ==
MBEDTLS_SSL_EARLY_DATA_TRY_TO_DEPROTECT_AND_DISCARD)) {
MBEDTLS_SSL_DEBUG_MSG(
3, ("EarlyData: deprotect and discard app data records."));
ret = mbedtls_ssl_tls13_check_early_data_len(ssl, rec->data_len);
if (ret != 0) {
return ret;
}
ret = MBEDTLS_ERR_SSL_CONTINUE_PROCESSING;
}
#endif /* MBEDTLS_SSL_EARLY_DATA && MBEDTLS_SSL_SRV_C */
#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 */
/*
* The decryption of the record failed, no reason to ignore it,
* return in error with the decryption error code.
*/
return ret;
}
#if defined(MBEDTLS_SSL_EARLY_DATA) && defined(MBEDTLS_SSL_SRV_C)
/*
* If the server were discarding protected records that it fails to
* deprotect because it has rejected early data, as we have just
* deprotected successfully a record, the server has to resume normal
* operation and fail the connection if the deprotection of a record
* fails.
*/
if (ssl->discard_early_data_record ==
MBEDTLS_SSL_EARLY_DATA_TRY_TO_DEPROTECT_AND_DISCARD) {
ssl->discard_early_data_record = MBEDTLS_SSL_EARLY_DATA_NO_DISCARD;
}
#endif /* MBEDTLS_SSL_EARLY_DATA && MBEDTLS_SSL_SRV_C */
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->tls_version == MBEDTLS_SSL_VERSION_TLS1_2
&& 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 = MBEDTLS_SSL_SEQUENCE_NUMBER_LEN;
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_EARLY_DATA) && defined(MBEDTLS_SSL_SRV_C)
/*
* Although the server rejected early data because it needed to send an
* HelloRetryRequest message, it might receive early data as long as it has
* not received the client Finished message.
* The early data is encrypted with early keys and should be ignored as
* stated in section 4.2.10 of RFC 8446 (second case):
*
* "The server then ignores early data by skipping all records with an
* external content type of "application_data" (indicating that they are
* encrypted), up to the configured max_early_data_size. Ignore application
* data message before 2nd ClientHello when early_data was received in 1st
* ClientHello."
*/
if (ssl->discard_early_data_record == MBEDTLS_SSL_EARLY_DATA_DISCARD) {
if (rec->type == MBEDTLS_SSL_MSG_APPLICATION_DATA) {
ret = mbedtls_ssl_tls13_check_early_data_len(ssl, rec->data_len);
if (ret != 0) {
return ret;
}
MBEDTLS_SSL_DEBUG_MSG(
3, ("EarlyData: Ignore application message before 2nd ClientHello"));
return MBEDTLS_ERR_SSL_CONTINUE_PROCESSING;
} else if (rec->type == MBEDTLS_SSL_MSG_HANDSHAKE) {
ssl->discard_early_data_record = MBEDTLS_SSL_EARLY_DATA_NO_DISCARD;
}
}
#endif /* MBEDTLS_SSL_EARLY_DATA && MBEDTLS_SSL_SRV_C */
#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 (rec->data_len > 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(). */
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_consume_current_message(mbedtls_ssl_context *ssl);
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_get_next_record(mbedtls_ssl_context *ssl);
MBEDTLS_CHECK_RETURN_CRITICAL
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) {
int dtls_have_buffered = 0;
#if defined(MBEDTLS_SSL_PROTO_DTLS)
/* 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) {
dtls_have_buffered = 1;
}
}
#endif /* MBEDTLS_SSL_PROTO_DTLS */
if (dtls_have_buffered == 0) {
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) {
ret = mbedtls_ssl_update_handshake_status(ssl);
if (0 != ret) {
MBEDTLS_SSL_DEBUG_RET(1, ("mbedtls_ssl_update_handshake_status"), ret);
return ret;
}
}
} 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)
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_next_record_is_in_datagram(mbedtls_ssl_context *ssl)
{
if (ssl->in_left > ssl->next_record_offset) {
return 1;
}
return 0;
}
MBEDTLS_CHECK_RETURN_CRITICAL
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_message"));
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 = MBEDTLS_GET_UINT24_BE(hs_buf->data, 1);
/* 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;
}
MBEDTLS_CHECK_RETURN_CRITICAL
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;
}
MBEDTLS_CHECK_RETURN_CRITICAL
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 = MBEDTLS_GET_UINT16_BE(ssl->in_msg, 4);
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 */
MBEDTLS_CHECK_RETURN_CRITICAL
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;
}
MBEDTLS_CHECK_RETURN_CRITICAL
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;
}
}
MBEDTLS_CHECK_RETURN_CRITICAL
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;
}
MBEDTLS_CHECK_RETURN_CRITICAL
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 */
MBEDTLS_CHECK_RETURN_CRITICAL
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 (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;
}
/* 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;
MBEDTLS_PUT_UINT16_BE(rec.data_len, ssl->in_len, 0);
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 defined(MBEDTLS_SSL_PROTO_TLS1_3)
if (ssl->tls_version == MBEDTLS_SSL_VERSION_TLS1_3) {
#if defined(MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE)
MBEDTLS_SSL_DEBUG_MSG(1,
("Ignore ChangeCipherSpec in TLS 1.3 compatibility mode"));
return MBEDTLS_ERR_SSL_CONTINUE_PROCESSING;
#else
MBEDTLS_SSL_DEBUG_MSG(1,
("ChangeCipherSpec invalid in TLS 1.3 without compatibility mode"));
return MBEDTLS_ERR_SSL_INVALID_RECORD;
#endif /* MBEDTLS_SSL_TLS1_3_COMPATIBILITY_MODE */
}
#endif /* MBEDTLS_SSL_PROTO_TLS1_3 */
}
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 &&
mbedtls_ssl_is_handshake_over(ssl) == 0
#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 &&
mbedtls_ssl_is_handshake_over(ssl) == 1) {
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;
}
if (ssl->out_left != 0) {
return mbedtls_ssl_flush_output(ssl);
}
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"));
#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
ssl->transform_in = ssl->transform_negotiate;
#endif
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, MBEDTLS_SSL_SEQUENCE_NUMBER_LEN);
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)
{
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 + MBEDTLS_SSL_SEQUENCE_NUMBER_LEN;
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 + MBEDTLS_SSL_SEQUENCE_NUMBER_LEN;
#endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
ssl->out_iv = ssl->out_len + 2;
} else
#endif
{
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 + MBEDTLS_SSL_SEQUENCE_NUMBER_LEN;
ssl->in_len = ssl->in_cid; /* Default: no CID */
#else /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
ssl->in_len = ssl->in_ctr + MBEDTLS_SSL_SEQUENCE_NUMBER_LEN;
#endif /* MBEDTLS_SSL_DTLS_CONNECTION_ID */
ssl->in_iv = ssl->in_len + 2;
} else
#endif
{
ssl->in_ctr = ssl->in_hdr - MBEDTLS_SSL_SEQUENCE_NUMBER_LEN;
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_ctr = ssl->out_buf;
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;
#if defined(MBEDTLS_USE_PSA_CRYPTO)
psa_key_attributes_t attr = PSA_KEY_ATTRIBUTES_INIT;
psa_key_type_t key_type;
#endif /* MBEDTLS_USE_PSA_CRYPTO */
size_t out_hdr_len = mbedtls_ssl_out_hdr_len(ssl);
if (transform == NULL) {
return (int) out_hdr_len;
}
#if defined(MBEDTLS_USE_PSA_CRYPTO)
if (transform->psa_alg == PSA_ALG_GCM ||
transform->psa_alg == PSA_ALG_CCM ||
transform->psa_alg == PSA_ALG_AEAD_WITH_SHORTENED_TAG(PSA_ALG_CCM, 8) ||
transform->psa_alg == PSA_ALG_CHACHA20_POLY1305 ||
transform->psa_alg == MBEDTLS_SSL_NULL_CIPHER) {
transform_expansion = transform->minlen;
} else if (transform->psa_alg == PSA_ALG_CBC_NO_PADDING) {
(void) psa_get_key_attributes(transform->psa_key_enc, &attr);
key_type = psa_get_key_type(&attr);
block_size = PSA_BLOCK_CIPHER_BLOCK_LENGTH(key_type);
/* 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 1.2 or higher, an explicit IV is added
* after the record header. */
#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
transform_expansion += block_size;
#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
} else {
MBEDTLS_SSL_DEBUG_MSG(1,
("Unsupported psa_alg spotted in mbedtls_ssl_get_record_expansion()"));
return MBEDTLS_ERR_SSL_INTERNAL_ERROR;
}
#else
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 1.2 or higher, an explicit IV is added
* after the record header. */
#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
transform_expansion += block_size;
#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
break;
default:
MBEDTLS_SSL_DEBUG_MSG(1, ("should never happen"));
return MBEDTLS_ERR_SSL_INTERNAL_ERROR;
}
#endif /* MBEDTLS_USE_PSA_CRYPTO */
#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.
*/
MBEDTLS_CHECK_RETURN_CRITICAL
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 (mbedtls_ssl_is_handshake_over(ssl) == 0 ||
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],
MBEDTLS_SSL_SEQUENCE_NUMBER_LEN - ep_len);
out_ctr_cmp = memcmp(&ssl->cur_out_ctr[ep_len],
&ssl->conf->renego_period[ep_len],
sizeof(ssl->cur_out_ctr) - 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 */
#if defined(MBEDTLS_SSL_PROTO_TLS1_3)
#if defined(MBEDTLS_SSL_SESSION_TICKETS) && defined(MBEDTLS_SSL_CLI_C)
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_check_new_session_ticket(mbedtls_ssl_context *ssl)
{
if ((ssl->in_hslen == mbedtls_ssl_hs_hdr_len(ssl)) ||
(ssl->in_msg[0] != MBEDTLS_SSL_HS_NEW_SESSION_TICKET)) {
return 0;
}
ssl->keep_current_message = 1;
MBEDTLS_SSL_DEBUG_MSG(3, ("NewSessionTicket received"));
mbedtls_ssl_handshake_set_state(ssl,
MBEDTLS_SSL_TLS1_3_NEW_SESSION_TICKET);
return MBEDTLS_ERR_SSL_WANT_READ;
}
#endif /* MBEDTLS_SSL_SESSION_TICKETS && MBEDTLS_SSL_CLI_C */
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls13_handle_hs_message_post_handshake(mbedtls_ssl_context *ssl)
{
MBEDTLS_SSL_DEBUG_MSG(3, ("received post-handshake message"));
#if defined(MBEDTLS_SSL_SESSION_TICKETS) && defined(MBEDTLS_SSL_CLI_C)
if (ssl->conf->endpoint == MBEDTLS_SSL_IS_CLIENT) {
int ret = ssl_tls13_check_new_session_ticket(ssl);
if (ret != 0) {
return ret;
}
}
#endif /* MBEDTLS_SSL_SESSION_TICKETS && MBEDTLS_SSL_CLI_C */
/* Fail in all other cases. */
return MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE;
}
#endif /* MBEDTLS_SSL_PROTO_TLS1_3 */
#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
/* This function is called from mbedtls_ssl_read() when a handshake message is
* received after the initial handshake. In this context, handshake messages
* may only be sent for the purpose of initiating renegotiations.
*
* This function is introduced as a separate helper since the handling
* of post-handshake handshake messages changes significantly in TLS 1.3,
* and having a helper function allows to distinguish between TLS <= 1.2 and
* TLS 1.3 in the future without bloating the logic of mbedtls_ssl_read().
*/
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_tls12_handle_hs_message_post_handshake(mbedtls_ssl_context *ssl)
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
/*
* - 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) {
return 0;
}
#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) {
return 0;
}
#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 ((ret = mbedtls_ssl_send_alert_message(ssl,
MBEDTLS_SSL_ALERT_LEVEL_WARNING,
MBEDTLS_SSL_ALERT_MSG_NO_RENEGOTIATION)) != 0) {
return ret;
}
}
return 0;
}
#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
MBEDTLS_CHECK_RETURN_CRITICAL
static int ssl_handle_hs_message_post_handshake(mbedtls_ssl_context *ssl)
{
/* Check protocol version and dispatch accordingly. */
#if defined(MBEDTLS_SSL_PROTO_TLS1_3)
if (ssl->tls_version == MBEDTLS_SSL_VERSION_TLS1_3) {
return ssl_tls13_handle_hs_message_post_handshake(ssl);
}
#endif /* MBEDTLS_SSL_PROTO_TLS1_3 */
#if defined(MBEDTLS_SSL_PROTO_TLS1_2)
if (ssl->tls_version <= MBEDTLS_SSL_VERSION_TLS1_2) {
return ssl_tls12_handle_hs_message_post_handshake(ssl);
}
#endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
/* Should never happen */
return MBEDTLS_ERR_SSL_INTERNAL_ERROR;
}
/*
* brief Read at most 'len' application data bytes from the input
* buffer.
*
* param ssl SSL context:
* - First byte of application data not read yet in the input
* buffer located at address `in_offt`.
* - The number of bytes of data not read yet is `in_msglen`.
* param buf buffer that will hold the data
* param len maximum number of bytes to read
*
* note The function updates the fields `in_offt` and `in_msglen`
* according to the number of bytes read.
*
* return The number of bytes read.
*/
static int ssl_read_application_data(
mbedtls_ssl_context *ssl, unsigned char *buf, size_t len)
{
size_t n = (len < ssl->in_msglen) ? len : ssl->in_msglen;
if (len != 0) {
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;
}
return (int) n;
}
/*
* 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;
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) {
ret = ssl_handle_hs_message_post_handshake(ssl);
if (ret != 0) {
MBEDTLS_SSL_DEBUG_RET(1, "ssl_handle_hs_message_post_handshake",
ret);
return ret;
}
/* At this point, we don't know whether the renegotiation triggered
* by the post-handshake message 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 cases, 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 (mbedtls_ssl_is_handshake_over(ssl) == 1) {
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 */
}
ret = ssl_read_application_data(ssl, buf, len);
MBEDTLS_SSL_DEBUG_MSG(2, ("<= read"));
return ret;
}
#if defined(MBEDTLS_SSL_SRV_C) && defined(MBEDTLS_SSL_EARLY_DATA)
int mbedtls_ssl_read_early_data(mbedtls_ssl_context *ssl,
unsigned char *buf, size_t len)
{
if (ssl == NULL || (ssl->conf == NULL)) {
return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
}
/*
* The server may receive early data only while waiting for the End of
* Early Data handshake message.
*/
if ((ssl->state != MBEDTLS_SSL_END_OF_EARLY_DATA) ||
(ssl->in_offt == NULL)) {
return MBEDTLS_ERR_SSL_CANNOT_READ_EARLY_DATA;
}
return ssl_read_application_data(ssl, buf, len);
}
#endif /* MBEDTLS_SSL_SRV_C && MBEDTLS_SSL_EARLY_DATA */
/*
* 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.
*/
MBEDTLS_CHECK_RETURN_CRITICAL
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;
if (len > 0) {
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 (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;
}
}
ret = ssl_write_real(ssl, buf, len);
MBEDTLS_SSL_DEBUG_MSG(2, ("<= write"));
return ret;
}
#if defined(MBEDTLS_SSL_EARLY_DATA) && defined(MBEDTLS_SSL_CLI_C)
int mbedtls_ssl_write_early_data(mbedtls_ssl_context *ssl,
const unsigned char *buf, size_t len)
{
int ret = MBEDTLS_ERR_ERROR_CORRUPTION_DETECTED;
const struct mbedtls_ssl_config *conf;
uint32_t remaining;
MBEDTLS_SSL_DEBUG_MSG(2, ("=> write early_data"));
if (ssl == NULL || (conf = ssl->conf) == NULL) {
return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
}
if (conf->endpoint != MBEDTLS_SSL_IS_CLIENT) {
return MBEDTLS_ERR_SSL_BAD_INPUT_DATA;
}
if ((!mbedtls_ssl_conf_is_tls13_enabled(conf)) ||
(conf->transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) ||
(conf->early_data_enabled != MBEDTLS_SSL_EARLY_DATA_ENABLED)) {
return MBEDTLS_ERR_SSL_CANNOT_WRITE_EARLY_DATA;
}
if (ssl->tls_version != MBEDTLS_SSL_VERSION_TLS1_3) {
return MBEDTLS_ERR_SSL_CANNOT_WRITE_EARLY_DATA;
}
/*
* If we are at the beginning of the handshake, the early data state being
* equal to MBEDTLS_SSL_EARLY_DATA_STATE_IDLE or
* MBEDTLS_SSL_EARLY_DATA_STATE_IND_SENT advance the handshake just
* enough to be able to send early data if possible. That way, we can
* guarantee that when starting the handshake with this function we will
* send at least one record of early data. Note that when the state is
* MBEDTLS_SSL_EARLY_DATA_STATE_IND_SENT and not yet
* MBEDTLS_SSL_EARLY_DATA_STATE_CAN_WRITE, we cannot send early data
* as the early data outbound transform has not been set as we may have to
* first send a dummy CCS in clear.
*/
if ((ssl->early_data_state == MBEDTLS_SSL_EARLY_DATA_STATE_IDLE) ||
(ssl->early_data_state == MBEDTLS_SSL_EARLY_DATA_STATE_IND_SENT)) {
while ((ssl->early_data_state == MBEDTLS_SSL_EARLY_DATA_STATE_IDLE) ||
(ssl->early_data_state == MBEDTLS_SSL_EARLY_DATA_STATE_IND_SENT)) {
ret = mbedtls_ssl_handshake_step(ssl);
if (ret != 0) {
MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_handshake_step", ret);
return ret;
}
ret = mbedtls_ssl_flush_output(ssl);
if (ret != 0) {
MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_flush_output", ret);
return ret;
}
}
remaining = ssl->session_negotiate->max_early_data_size;
} else {
/*
* If we are past the point where we can send early data or we have
* already reached the maximum early data size, return immediatly.
* Otherwise, progress the handshake as much as possible to not delay
* it too much. If we reach a point where we can still send early data,
* then we will send some.
*/
if ((ssl->early_data_state != MBEDTLS_SSL_EARLY_DATA_STATE_CAN_WRITE) &&
(ssl->early_data_state != MBEDTLS_SSL_EARLY_DATA_STATE_ACCEPTED)) {
return MBEDTLS_ERR_SSL_CANNOT_WRITE_EARLY_DATA;
}
remaining = ssl->session_negotiate->max_early_data_size -
ssl->total_early_data_size;
if (remaining == 0) {
return MBEDTLS_ERR_SSL_CANNOT_WRITE_EARLY_DATA;
}
ret = mbedtls_ssl_handshake(ssl);
if ((ret != 0) && (ret != MBEDTLS_ERR_SSL_WANT_READ)) {
MBEDTLS_SSL_DEBUG_RET(1, "mbedtls_ssl_handshake", ret);
return ret;
}
}
if (((ssl->early_data_state != MBEDTLS_SSL_EARLY_DATA_STATE_CAN_WRITE) &&
(ssl->early_data_state != MBEDTLS_SSL_EARLY_DATA_STATE_ACCEPTED))
|| (remaining == 0)) {
return MBEDTLS_ERR_SSL_CANNOT_WRITE_EARLY_DATA;
}
if (len > remaining) {
len = remaining;
}
ret = ssl_write_real(ssl, buf, len);
if (ret >= 0) {
ssl->total_early_data_size += ret;
}
MBEDTLS_SSL_DEBUG_MSG(2, ("<= write early_data, ret=%d", ret));
return ret;
}
#endif /* MBEDTLS_SSL_EARLY_DATA && MBEDTLS_SSL_CLI_C */
/*
* 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 (mbedtls_ssl_is_handshake_over(ssl) == 1) {
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;
}
#if defined(MBEDTLS_USE_PSA_CRYPTO)
psa_destroy_key(transform->psa_key_enc);
psa_destroy_key(transform->psa_key_dec);
#else
mbedtls_cipher_free(&transform->cipher_ctx_enc);
mbedtls_cipher_free(&transform->cipher_ctx_dec);
#endif /* MBEDTLS_USE_PSA_CRYPTO */
#if defined(MBEDTLS_SSL_SOME_SUITES_USE_MAC)
#if defined(MBEDTLS_USE_PSA_CRYPTO)
psa_destroy_key(transform->psa_mac_enc);
psa_destroy_key(transform->psa_mac_dec);
#else
mbedtls_md_free(&transform->md_ctx_enc);
mbedtls_md_free(&transform->md_ctx_dec);
#endif /* MBEDTLS_USE_PSA_CRYPTO */
#endif
mbedtls_platform_zeroize(transform, sizeof(mbedtls_ssl_transform));
}
void mbedtls_ssl_set_inbound_transform(mbedtls_ssl_context *ssl,
mbedtls_ssl_transform *transform)
{
ssl->transform_in = transform;
memset(ssl->in_ctr, 0, MBEDTLS_SSL_SEQUENCE_NUMBER_LEN);
}
void mbedtls_ssl_set_outbound_transform(mbedtls_ssl_context *ssl,
mbedtls_ssl_transform *transform)
{
ssl->transform_out = transform;
memset(ssl->cur_out_ctr, 0, sizeof(ssl->cur_out_ctr));
}
#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_zeroize_and_free(hs_buf->data, hs_buf->data_len);
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, map as follows, then use 1's complement (v -> ~v):
* 1.x <-> 3.x+1 for x != 0 (DTLS 1.2 based on TLS 1.2)
* DTLS 1.0 is stored as TLS 1.1 internally
*/
void mbedtls_ssl_write_version(unsigned char version[2], int transport,
mbedtls_ssl_protocol_version tls_version)
{
uint16_t tls_version_formatted;
#if defined(MBEDTLS_SSL_PROTO_DTLS)
if (transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) {
tls_version_formatted =
~(tls_version - (tls_version == 0x0302 ? 0x0202 : 0x0201));
} else
#else
((void) transport);
#endif
{
tls_version_formatted = (uint16_t) tls_version;
}
MBEDTLS_PUT_UINT16_BE(tls_version_formatted, version, 0);
}
uint16_t mbedtls_ssl_read_version(const unsigned char version[2],
int transport)
{
uint16_t tls_version = MBEDTLS_GET_UINT16_BE(version, 0);
#if defined(MBEDTLS_SSL_PROTO_DTLS)
if (transport == MBEDTLS_SSL_TRANSPORT_DATAGRAM) {
tls_version =
~(tls_version - (tls_version == 0xfeff ? 0x0202 : 0x0201));
}
#else
((void) transport);
#endif
return tls_version;
}
/*
* Send pending fatal alert.
* 0, No alert message.
* !0, if mbedtls_ssl_send_alert_message() returned in error, the error code it
* returned, ssl->alert_reason otherwise.
*/
int mbedtls_ssl_handle_pending_alert(mbedtls_ssl_context *ssl)
{
int ret;
/* No pending alert, return success*/
if (ssl->send_alert == 0) {
return 0;
}
ret = mbedtls_ssl_send_alert_message(ssl,
MBEDTLS_SSL_ALERT_LEVEL_FATAL,
ssl->alert_type);
/* If mbedtls_ssl_send_alert_message() returned with MBEDTLS_ERR_SSL_WANT_WRITE,
* do not clear the alert to be able to send it later.
*/
if (ret != MBEDTLS_ERR_SSL_WANT_WRITE) {
ssl->send_alert = 0;
}
if (ret != 0) {
return ret;
}
return ssl->alert_reason;
}
/*
* Set pending fatal alert flag.
*/
void mbedtls_ssl_pend_fatal_alert(mbedtls_ssl_context *ssl,
unsigned char alert_type,
int alert_reason)
{
ssl->send_alert = 1;
ssl->alert_type = alert_type;
ssl->alert_reason = alert_reason;
}
#endif /* MBEDTLS_SSL_TLS_C */