diff --git a/ChangeLog.d/fix-cipher-iv.txt b/ChangeLog.d/fix-cipher-iv.txt new file mode 100644 index 000000000..e7af6414a --- /dev/null +++ b/ChangeLog.d/fix-cipher-iv.txt @@ -0,0 +1,5 @@ +Security + * In psa_cipher_generate_iv() and psa_cipher_encrypt(), do not read back + from the output buffer. This fixes a potential policy bypass or decryption + oracle vulnerability if the output buffer is in memory that is shared with + an untrusted application. diff --git a/library/psa_crypto.c b/library/psa_crypto.c index 5aed67181..3bf470b2f 100644 --- a/library/psa_crypto.c +++ b/library/psa_crypto.c @@ -3379,8 +3379,8 @@ psa_status_t psa_cipher_generate_iv( psa_cipher_operation_t *operation, size_t *iv_length ) { psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED; - - *iv_length = 0; + uint8_t local_iv[PSA_CIPHER_IV_MAX_SIZE]; + size_t default_iv_length; if( operation->id == 0 ) { @@ -3394,28 +3394,38 @@ psa_status_t psa_cipher_generate_iv( psa_cipher_operation_t *operation, goto exit; } - if( iv_size < operation->default_iv_length ) + default_iv_length = operation->default_iv_length; + if( iv_size < default_iv_length ) { status = PSA_ERROR_BUFFER_TOO_SMALL; goto exit; } - status = psa_generate_random( iv, operation->default_iv_length ); + if( default_iv_length > PSA_CIPHER_IV_MAX_SIZE ) + { + status = PSA_ERROR_GENERIC_ERROR; + goto exit; + } + + status = psa_generate_random( local_iv, default_iv_length ); if( status != PSA_SUCCESS ) goto exit; status = psa_driver_wrapper_cipher_set_iv( operation, - iv, - operation->default_iv_length ); + local_iv, default_iv_length ); exit: if( status == PSA_SUCCESS ) { + memcpy( iv, local_iv, default_iv_length ); + *iv_length = default_iv_length; operation->iv_set = 1; - *iv_length = operation->default_iv_length; } else + { + *iv_length = 0; psa_cipher_abort( operation ); + } return( status ); } @@ -3556,50 +3566,67 @@ psa_status_t psa_cipher_encrypt( mbedtls_svc_key_id_t key, { psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED; psa_status_t unlock_status = PSA_ERROR_CORRUPTION_DETECTED; - psa_key_slot_t *slot; - psa_key_type_t key_type; - size_t iv_length; - - *output_length = 0; + psa_key_slot_t *slot = NULL; + uint8_t local_iv[PSA_CIPHER_IV_MAX_SIZE]; + size_t default_iv_length = 0; if( ! PSA_ALG_IS_CIPHER( alg ) ) - return( PSA_ERROR_INVALID_ARGUMENT ); + { + status = PSA_ERROR_INVALID_ARGUMENT; + goto exit; + } status = psa_get_and_lock_key_slot_with_policy( key, &slot, PSA_KEY_USAGE_ENCRYPT, alg ); if( status != PSA_SUCCESS ) - return( status ); + goto exit; psa_key_attributes_t attributes = { .core = slot->attr }; - key_type = slot->attr.type; - iv_length = PSA_CIPHER_IV_LENGTH( key_type, alg ); - - if( iv_length > 0 ) + default_iv_length = PSA_CIPHER_IV_LENGTH( slot->attr.type, alg ); + if( default_iv_length > PSA_CIPHER_IV_MAX_SIZE ) { - if( output_size < iv_length ) + status = PSA_ERROR_GENERIC_ERROR; + goto exit; + } + + if( default_iv_length > 0 ) + { + if( output_size < default_iv_length ) { status = PSA_ERROR_BUFFER_TOO_SMALL; goto exit; } - status = psa_generate_random( output, iv_length ); + status = psa_generate_random( local_iv, default_iv_length ); if( status != PSA_SUCCESS ) goto exit; } status = psa_driver_wrapper_cipher_encrypt( &attributes, slot->key.data, slot->key.bytes, - alg, input, input_length, - output, output_size, output_length ); + alg, local_iv, default_iv_length, input, input_length, + output + default_iv_length, output_size - default_iv_length, + output_length ); exit: unlock_status = psa_unlock_key_slot( slot ); + if( status == PSA_SUCCESS ) + status = unlock_status; - return( ( status == PSA_SUCCESS ) ? unlock_status : status ); + if( status == PSA_SUCCESS ) + { + if( default_iv_length > 0 ) + memcpy( output, local_iv, default_iv_length ); + *output_length += default_iv_length; + } + else + *output_length = 0; + + return( status ); } psa_status_t psa_cipher_decrypt( mbedtls_svc_key_id_t key, @@ -3612,18 +3639,19 @@ psa_status_t psa_cipher_decrypt( mbedtls_svc_key_id_t key, { psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED; psa_status_t unlock_status = PSA_ERROR_CORRUPTION_DETECTED; - psa_key_slot_t *slot; - - *output_length = 0; + psa_key_slot_t *slot = NULL; if( ! PSA_ALG_IS_CIPHER( alg ) ) - return( PSA_ERROR_INVALID_ARGUMENT ); + { + status = PSA_ERROR_INVALID_ARGUMENT; + goto exit; + } status = psa_get_and_lock_key_slot_with_policy( key, &slot, PSA_KEY_USAGE_DECRYPT, alg ); if( status != PSA_SUCCESS ) - return( status ); + goto exit; psa_key_attributes_t attributes = { .core = slot->attr @@ -3642,8 +3670,13 @@ psa_status_t psa_cipher_decrypt( mbedtls_svc_key_id_t key, exit: unlock_status = psa_unlock_key_slot( slot ); + if( status == PSA_SUCCESS ) + status = unlock_status; - return( ( status == PSA_SUCCESS ) ? unlock_status : status ); + if( status != PSA_SUCCESS ) + *output_length = 0; + + return( status ); } diff --git a/library/psa_crypto_cipher.c b/library/psa_crypto_cipher.c index 713c3d17d..22f536384 100644 --- a/library/psa_crypto_cipher.c +++ b/library/psa_crypto_cipher.c @@ -472,6 +472,8 @@ static psa_status_t cipher_encrypt( const psa_key_attributes_t *attributes, const uint8_t *key_buffer, size_t key_buffer_size, psa_algorithm_t alg, + const uint8_t *iv, + size_t iv_length, const uint8_t *input, size_t input_length, uint8_t *output, @@ -480,38 +482,32 @@ static psa_status_t cipher_encrypt( const psa_key_attributes_t *attributes, { psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED; mbedtls_psa_cipher_operation_t operation = MBEDTLS_PSA_CIPHER_OPERATION_INIT; - size_t olength, accumulated_length; + size_t update_output_length, finish_output_length; status = cipher_encrypt_setup( &operation, attributes, key_buffer, key_buffer_size, alg ); if( status != PSA_SUCCESS ) goto exit; - accumulated_length = 0; - if( operation.iv_length > 0 ) + if( iv_length > 0 ) { - status = cipher_set_iv( &operation, output, operation.iv_length ); + status = cipher_set_iv( &operation, iv, iv_length ); if( status != PSA_SUCCESS ) goto exit; - - accumulated_length = operation.iv_length; } status = cipher_update( &operation, input, input_length, - output + operation.iv_length, - output_size - operation.iv_length, - &olength ); + output, output_size, &update_output_length ); if( status != PSA_SUCCESS ) goto exit; - accumulated_length += olength; - - status = cipher_finish( &operation, output + accumulated_length, - output_size - accumulated_length, &olength ); + status = cipher_finish( &operation, output + update_output_length, + output_size - update_output_length, + &finish_output_length ); if( status != PSA_SUCCESS ) goto exit; - *output_length = accumulated_length + olength; + *output_length = update_output_length + finish_output_length; exit: if( status == PSA_SUCCESS ) @@ -627,6 +623,8 @@ psa_status_t mbedtls_psa_cipher_encrypt( const psa_key_attributes_t *attributes, const uint8_t *key_buffer, size_t key_buffer_size, psa_algorithm_t alg, + const uint8_t *iv, + size_t iv_length, const uint8_t *input, size_t input_length, uint8_t *output, @@ -634,7 +632,7 @@ psa_status_t mbedtls_psa_cipher_encrypt( const psa_key_attributes_t *attributes, size_t *output_length ) { return( cipher_encrypt( attributes, key_buffer, key_buffer_size, - alg, input, input_length, + alg, iv, iv_length, input, input_length, output, output_size, output_length ) ); } @@ -713,6 +711,8 @@ psa_status_t mbedtls_transparent_test_driver_cipher_encrypt( const uint8_t *key_buffer, size_t key_buffer_size, psa_algorithm_t alg, + const uint8_t *iv, + size_t iv_length, const uint8_t *input, size_t input_length, uint8_t *output, @@ -720,7 +720,7 @@ psa_status_t mbedtls_transparent_test_driver_cipher_encrypt( size_t *output_length ) { return( cipher_encrypt( attributes, key_buffer, key_buffer_size, - alg, input, input_length, + alg, iv, iv_length, input, input_length, output, output_size, output_length ) ); } diff --git a/library/psa_crypto_cipher.h b/library/psa_crypto_cipher.h index 5971e8d3f..76ff22acf 100644 --- a/library/psa_crypto_cipher.h +++ b/library/psa_crypto_cipher.h @@ -213,16 +213,12 @@ psa_status_t mbedtls_psa_cipher_abort( mbedtls_psa_cipher_operation_t *operation * \param[in] alg The cipher algorithm to compute * (\c PSA_ALG_XXX value such that * #PSA_ALG_IS_CIPHER(\p alg) is true). - * \param[in] input Buffer containing the message to encrypt. - * \param[in] input_length Size of the \p input buffer in bytes. + * \param[in] iv Buffer containing the IV for encryption. The + * IV has been generated by the core. + * \param[in] iv_length Size of the \p iv in bytes. + * \param[in] input Buffer containing the message to encrypt. + * \param[in] input_length Size of the \p input buffer in bytes. * \param[in,out] output Buffer where the output is to be written. - * The core has generated and written the IV - * at the beginning of this buffer before - * this function is called. The size of the IV - * is PSA_CIPHER_IV_LENGTH( key_type, alg ) where - * \c key_type is the type of the key identified - * by \p key and \p alg is the cipher algorithm - * to compute. * \param[in] output_size Size of the \p output buffer in bytes. * \param[out] output_length On success, the number of bytes that make up * the returned output. Initialized to zero @@ -235,7 +231,7 @@ psa_status_t mbedtls_psa_cipher_abort( mbedtls_psa_cipher_operation_t *operation * \retval #PSA_ERROR_BUFFER_TOO_SMALL * The size of the \p output buffer is too small. * \retval #PSA_ERROR_INVALID_ARGUMENT - * The size of \p iv is not acceptable for the chosen algorithm, + * The size \p iv_length is not acceptable for the chosen algorithm, * or the chosen algorithm does not use an IV. * The total input size passed to this operation is not valid for * this particular algorithm. For example, the algorithm is a based @@ -249,6 +245,8 @@ psa_status_t mbedtls_psa_cipher_encrypt( const psa_key_attributes_t *attributes, const uint8_t *key_buffer, size_t key_buffer_size, psa_algorithm_t alg, + const uint8_t *iv, + size_t iv_length, const uint8_t *input, size_t input_length, uint8_t *output, @@ -342,6 +340,8 @@ psa_status_t mbedtls_transparent_test_driver_cipher_encrypt( const uint8_t *key_buffer, size_t key_buffer_size, psa_algorithm_t alg, + const uint8_t *iv, + size_t iv_length, const uint8_t *input, size_t input_length, uint8_t *output, diff --git a/library/psa_crypto_driver_wrappers.c b/library/psa_crypto_driver_wrappers.c index f7240ceac..5fba95547 100644 --- a/library/psa_crypto_driver_wrappers.c +++ b/library/psa_crypto_driver_wrappers.c @@ -740,6 +740,8 @@ psa_status_t psa_driver_wrapper_cipher_encrypt( const uint8_t *key_buffer, size_t key_buffer_size, psa_algorithm_t alg, + const uint8_t *iv, + size_t iv_length, const uint8_t *input, size_t input_length, uint8_t *output, @@ -761,6 +763,8 @@ psa_status_t psa_driver_wrapper_cipher_encrypt( key_buffer, key_buffer_size, alg, + iv, + iv_length, input, input_length, output, @@ -777,6 +781,8 @@ psa_status_t psa_driver_wrapper_cipher_encrypt( key_buffer, key_buffer_size, alg, + iv, + iv_length, input, input_length, output, @@ -794,6 +800,8 @@ psa_status_t psa_driver_wrapper_cipher_encrypt( key_buffer, key_buffer_size, alg, + iv, + iv_length, input, input_length, output, diff --git a/library/psa_crypto_driver_wrappers.h b/library/psa_crypto_driver_wrappers.h index 38a6ee82a..9eb08bc9f 100644 --- a/library/psa_crypto_driver_wrappers.h +++ b/library/psa_crypto_driver_wrappers.h @@ -102,6 +102,8 @@ psa_status_t psa_driver_wrapper_cipher_encrypt( const uint8_t *key_buffer, size_t key_buffer_size, psa_algorithm_t alg, + const uint8_t *iv, + size_t iv_length, const uint8_t *input, size_t input_length, uint8_t *output, diff --git a/tests/include/test/drivers/cipher.h b/tests/include/test/drivers/cipher.h index 4fe559618..c1aa616b5 100644 --- a/tests/include/test/drivers/cipher.h +++ b/tests/include/test/drivers/cipher.h @@ -57,6 +57,7 @@ psa_status_t mbedtls_test_transparent_cipher_encrypt( const psa_key_attributes_t *attributes, const uint8_t *key, size_t key_length, psa_algorithm_t alg, + const uint8_t *iv, size_t iv_length, const uint8_t *input, size_t input_length, uint8_t *output, size_t output_size, size_t *output_length); @@ -102,6 +103,7 @@ psa_status_t mbedtls_test_opaque_cipher_encrypt( const psa_key_attributes_t *attributes, const uint8_t *key, size_t key_length, psa_algorithm_t alg, + const uint8_t *iv, size_t iv_length, const uint8_t *input, size_t input_length, uint8_t *output, size_t output_size, size_t *output_length); diff --git a/tests/src/drivers/test_driver_cipher.c b/tests/src/drivers/test_driver_cipher.c index 6aca1938c..9e0dc30c5 100644 --- a/tests/src/drivers/test_driver_cipher.c +++ b/tests/src/drivers/test_driver_cipher.c @@ -44,6 +44,8 @@ psa_status_t mbedtls_test_transparent_cipher_encrypt( const uint8_t *key_buffer, size_t key_buffer_size, psa_algorithm_t alg, + const uint8_t *iv, + size_t iv_length, const uint8_t *input, size_t input_length, uint8_t *output, @@ -68,11 +70,9 @@ psa_status_t mbedtls_test_transparent_cipher_encrypt( if( mbedtls_test_driver_cipher_hooks.forced_status != PSA_SUCCESS ) return( mbedtls_test_driver_cipher_hooks.forced_status ); - psa_generate_random( output, PSA_CIPHER_IV_LENGTH( attributes->core.type, alg ) ); - return( mbedtls_transparent_test_driver_cipher_encrypt( attributes, key_buffer, key_buffer_size, - alg, input, input_length, + alg, iv, iv_length, input, input_length, output, output_size, output_length ) ); } @@ -246,6 +246,7 @@ psa_status_t mbedtls_test_opaque_cipher_encrypt( const psa_key_attributes_t *attributes, const uint8_t *key, size_t key_length, psa_algorithm_t alg, + const uint8_t *iv, size_t iv_length, const uint8_t *input, size_t input_length, uint8_t *output, size_t output_size, size_t *output_length) { @@ -253,6 +254,8 @@ psa_status_t mbedtls_test_opaque_cipher_encrypt( (void) key; (void) key_length; (void) alg; + (void) iv; + (void) iv_length; (void) input; (void) input_length; (void) output; diff --git a/tests/suites/test_suite_psa_crypto.function b/tests/suites/test_suite_psa_crypto.function index 9ed142423..eb9458fde 100644 --- a/tests/suites/test_suite_psa_crypto.function +++ b/tests/suites/test_suite_psa_crypto.function @@ -2600,6 +2600,9 @@ void cipher_encrypt_alg_without_iv( int alg_arg, mbedtls_svc_key_id_t key = MBEDTLS_SVC_KEY_ID_INIT; psa_key_type_t key_type = key_type_arg; psa_algorithm_t alg = alg_arg; + psa_cipher_operation_t operation = PSA_CIPHER_OPERATION_INIT; + uint8_t iv[1] = { 0x5a }; + size_t iv_length; unsigned char *output = NULL; size_t output_buffer_size = 0; size_t output_length = 0; @@ -2617,6 +2620,14 @@ void cipher_encrypt_alg_without_iv( int alg_arg, PSA_ASSERT( psa_import_key( &attributes, key_data->x, key_data->len, &key ) ); + PSA_ASSERT( psa_cipher_encrypt_setup( &operation, key, alg ) ); + TEST_EQUAL( psa_cipher_set_iv( &operation, iv, sizeof( iv ) ), + PSA_ERROR_BAD_STATE ); + PSA_ASSERT( psa_cipher_encrypt_setup( &operation, key, alg ) ); + TEST_EQUAL( psa_cipher_generate_iv( &operation, iv, sizeof( iv ), + &iv_length ), + PSA_ERROR_BAD_STATE ); + PSA_ASSERT( psa_cipher_encrypt( key, alg, input->x, input->len, output, output_buffer_size, &output_length ) ); TEST_ASSERT( output_length <= diff --git a/tests/suites/test_suite_psa_crypto_driver_wrappers.function b/tests/suites/test_suite_psa_crypto_driver_wrappers.function index 6d78ad51a..74cc03242 100644 --- a/tests/suites/test_suite_psa_crypto_driver_wrappers.function +++ b/tests/suites/test_suite_psa_crypto_driver_wrappers.function @@ -872,6 +872,39 @@ void cipher_entry_points( int alg_arg, int key_type_arg, PSA_ASSERT( psa_import_key( &attributes, key_data->x, key_data->len, &key ) ); + /* + * Test encrypt failure + * First test that if we don't force a driver error, encryption is + * successfull, then force driver error. + */ + status = psa_cipher_encrypt( + key, alg, input->x, input->len, + output, output_buffer_size, &function_output_length ); + TEST_EQUAL( mbedtls_test_driver_cipher_hooks.hits, 1 ); + TEST_EQUAL( status, PSA_SUCCESS ); + mbedtls_test_driver_cipher_hooks.hits = 0; + + mbedtls_test_driver_cipher_hooks.forced_status = PSA_ERROR_GENERIC_ERROR; + /* Set the output buffer in a given state. */ + for( size_t i = 0; i < output_buffer_size; i++ ) + output[i] = 0xa5; + + status = psa_cipher_encrypt( + key, alg, input->x, input->len, + output, output_buffer_size, &function_output_length ); + TEST_EQUAL( mbedtls_test_driver_cipher_hooks.hits, 1 ); + TEST_EQUAL( status, PSA_ERROR_GENERIC_ERROR ); + /* + * Check that the output buffer is still in the same state. + * This will fail if the output buffer is used by the core to pass the IV + * it generated to the driver (and is not restored). + */ + for( size_t i = 0; i < output_buffer_size; i++ ) + { + TEST_EQUAL( output[i], 0xa5 ); + } + mbedtls_test_driver_cipher_hooks.hits = 0; + /* Test setup call, encrypt */ mbedtls_test_driver_cipher_hooks.forced_status = PSA_ERROR_GENERIC_ERROR; status = psa_cipher_encrypt_setup( &operation, key, alg ); @@ -923,10 +956,23 @@ void cipher_entry_points( int alg_arg, int key_type_arg, mbedtls_test_driver_cipher_hooks.hits = 0; mbedtls_test_driver_cipher_hooks.forced_status = PSA_ERROR_GENERIC_ERROR; + /* Set the output buffer in a given state. */ + for( size_t i = 0; i < 16; i++ ) + output[i] = 0xa5; + status = psa_cipher_generate_iv( &operation, output, 16, &function_output_length ); /* When generating the IV fails, it should call abort too */ TEST_EQUAL( mbedtls_test_driver_cipher_hooks.hits, 2 ); TEST_EQUAL( status, mbedtls_test_driver_cipher_hooks.forced_status ); + /* + * Check that the output buffer is still in the same state. + * This will fail if the output buffer is used by the core to pass the IV + * it generated to the driver (and is not restored). + */ + for( size_t i = 0; i < 16; i++ ) + { + TEST_EQUAL( output[i], 0xa5 ); + } /* Failure should prevent further operations from executing on the driver */ mbedtls_test_driver_cipher_hooks.hits = 0; status = psa_cipher_update( &operation,