Move mbedtls_ct_hmac into ssl_msg.c

Signed-off-by: Dave Rodgman <dave.rodgman@arm.com>
This commit is contained in:
Dave Rodgman 2023-05-09 11:00:07 +01:00
parent 8c94e219f9
commit 2801f7fa8d
4 changed files with 288 additions and 278 deletions

View file

@ -431,227 +431,6 @@ void mbedtls_ct_memcpy_offset(unsigned char *dest,
}
}
#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
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_eq(output, aux_out, hash_size,
offset, data_len_secret);
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
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_eq(output, aux_out, hash_size,
offset, data_len_secret);
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 */
#if defined(MBEDTLS_BIGNUM_C)

View file

@ -236,63 +236,6 @@ void mbedtls_ct_memcpy_offset(unsigned char *dest,
size_t offset_max,
size_t len);
/** Compute the HMAC of variable-length data with constant flow.
*
* This function computes the HMAC of the concatenation of \p add_data and \p
* data, and does with a code flow and memory access pattern that does not
* depend on \p data_len_secret, but only on \p min_data_len and \p
* max_data_len. In particular, this function always reads exactly \p
* max_data_len bytes from \p data.
*
* \param ctx The HMAC context. It must have keys configured
* with mbedtls_md_hmac_starts() and use one of the
* following hashes: SHA-384, SHA-256, SHA-1 or MD-5.
* It is reset using mbedtls_md_hmac_reset() after
* the computation is complete to prepare for the
* next computation.
* \param add_data The first part of the message whose HMAC is being
* calculated. This must point to a readable buffer
* of \p add_data_len bytes.
* \param add_data_len The length of \p add_data in bytes.
* \param data The buffer containing the second part of the
* message. This must point to a readable buffer
* of \p max_data_len bytes.
* \param data_len_secret The length of the data to process in \p data.
* This must be no less than \p min_data_len and no
* greater than \p max_data_len.
* \param min_data_len The minimal length of the second part of the
* message, read from \p data.
* \param max_data_len The maximal length of the second part of the
* message, read from \p data.
* \param output The HMAC will be written here. This must point to
* a writable buffer of sufficient size to hold the
* HMAC value.
*
* \retval 0 on success.
* \retval #MBEDTLS_ERR_PLATFORM_HW_ACCEL_FAILED
* The hardware accelerator failed.
*/
#if defined(MBEDTLS_USE_PSA_CRYPTO)
int mbedtls_ct_hmac(mbedtls_svc_key_id_t key,
psa_algorithm_t 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);
#else
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);
#endif /* MBEDTLS_USE_PSA_CRYPTO */
#endif /* MBEDTLS_SSL_SOME_SUITES_USE_MAC */
#if defined(MBEDTLS_PKCS1_V15) && defined(MBEDTLS_RSA_C) && !defined(MBEDTLS_RSA_ALT)

View file

@ -2788,4 +2788,64 @@ static inline void mbedtls_ssl_session_clear_ticket_flags(
int mbedtls_ssl_tls13_finalize_client_hello(mbedtls_ssl_context *ssl);
#endif
#if defined(MBEDTLS_TEST_HOOKS) && defined(MBEDTLS_SSL_SOME_SUITES_USE_MAC)
/** Compute the HMAC of variable-length data with constant flow.
*
* This function computes the HMAC of the concatenation of \p add_data and \p
* data, and does with a code flow and memory access pattern that does not
* depend on \p data_len_secret, but only on \p min_data_len and \p
* max_data_len. In particular, this function always reads exactly \p
* max_data_len bytes from \p data.
*
* \param ctx The HMAC context. It must have keys configured
* with mbedtls_md_hmac_starts() and use one of the
* following hashes: SHA-384, SHA-256, SHA-1 or MD-5.
* It is reset using mbedtls_md_hmac_reset() after
* the computation is complete to prepare for the
* next computation.
* \param add_data The first part of the message whose HMAC is being
* calculated. This must point to a readable buffer
* of \p add_data_len bytes.
* \param add_data_len The length of \p add_data in bytes.
* \param data The buffer containing the second part of the
* message. This must point to a readable buffer
* of \p max_data_len bytes.
* \param data_len_secret The length of the data to process in \p data.
* This must be no less than \p min_data_len and no
* greater than \p max_data_len.
* \param min_data_len The minimal length of the second part of the
* message, read from \p data.
* \param max_data_len The maximal length of the second part of the
* message, read from \p data.
* \param output The HMAC will be written here. This must point to
* a writable buffer of sufficient size to hold the
* HMAC value.
*
* \retval 0 on success.
* \retval #MBEDTLS_ERR_PLATFORM_HW_ACCEL_FAILED
* The hardware accelerator failed.
*/
#if defined(MBEDTLS_USE_PSA_CRYPTO)
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);
#else
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);
#endif /* defined(MBEDTLS_USE_PSA_CRYPTO) */
#endif /* MBEDTLS_TEST_HOOKS && defined(MBEDTLS_SSL_SOME_SUITES_USE_MAC) */
#endif /* ssl_misc.h */

View file

@ -54,6 +54,234 @@
psa_generic_status_to_mbedtls)
#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_eq(output, aux_out, hash_size,
offset, data_len_secret);
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_eq(output, aux_out, hash_size,
offset, data_len_secret);
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);
/*