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Add parsing for Record Size Limit extension in TLS 1.3

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Fixes #7007

Signed-off-by: Jan Bruckner <jan@janbruckner.de>
This commit is contained in:
Jan Bruckner
2023-02-10 12:45:19 +01:00
parent 5a3629b613
commit 151f64283f
11 changed files with 158 additions and 25 deletions
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12
library/ssl_misc.h
View File

@ -107,6 +107,7 @@
#define MBEDTLS_SSL_EXT_ID_ENCRYPT_THEN_MAC 25
#define MBEDTLS_SSL_EXT_ID_EXTENDED_MASTER_SECRET 26
#define MBEDTLS_SSL_EXT_ID_SESSION_TICKET 27
#define MBEDTLS_SSL_EXT_ID_RECORD_SIZE_LIMIT 28
/* Utility for translating IANA extension type. */
uint32_t mbedtls_ssl_get_extension_id(unsigned int extension_type);
@ -167,6 +168,7 @@ uint32_t mbedtls_ssl_get_extension_mask(unsigned int extension_type);
MBEDTLS_SSL_EXT_MASK(CERT_AUTH) | \
MBEDTLS_SSL_EXT_MASK(POST_HANDSHAKE_AUTH) | \
MBEDTLS_SSL_EXT_MASK(SIG_ALG_CERT) | \
MBEDTLS_SSL_EXT_MASK(RECORD_SIZE_LIMIT) | \
MBEDTLS_SSL_TLS1_3_EXT_MASK_UNRECOGNIZED)
/* RFC 8446 section 4.2. Allowed extensions for EncryptedExtensions */
@ -179,7 +181,8 @@ uint32_t mbedtls_ssl_get_extension_mask(unsigned int extension_type);
MBEDTLS_SSL_EXT_MASK(ALPN) | \
MBEDTLS_SSL_EXT_MASK(CLI_CERT_TYPE) | \
MBEDTLS_SSL_EXT_MASK(SERV_CERT_TYPE) | \
MBEDTLS_SSL_EXT_MASK(EARLY_DATA))
MBEDTLS_SSL_EXT_MASK(EARLY_DATA) | \
MBEDTLS_SSL_EXT_MASK(RECORD_SIZE_LIMIT))
/* RFC 8446 section 4.2. Allowed extensions for CertificateRequest */
#define MBEDTLS_SSL_TLS1_3_ALLOWED_EXTS_OF_CR \
@ -2662,6 +2665,13 @@ int mbedtls_ssl_parse_server_name_ext(mbedtls_ssl_context *ssl,
const unsigned char *end);
#endif /* MBEDTLS_SSL_SERVER_NAME_INDICATION */
#if defined(MBEDTLS_SSL_RECORD_SIZE_LIMIT)
MBEDTLS_CHECK_RETURN_CRITICAL
int mbedtls_ssl_tls13_parse_record_size_limit_ext(mbedtls_ssl_context *ssl,
const unsigned char *buf,
const unsigned char *end);
#endif /* MBEDTLS_SSL_RECORD_SIZE_LIMIT */
#if defined(MBEDTLS_SSL_ALPN)
MBEDTLS_CHECK_RETURN_CRITICAL
int mbedtls_ssl_parse_alpn_ext(mbedtls_ssl_context *ssl,

9
library/ssl_tls.c
View File

@ -593,6 +593,9 @@ uint32_t mbedtls_ssl_get_extension_id(unsigned int extension_type)
case MBEDTLS_TLS_EXT_EXTENDED_MASTER_SECRET:
return MBEDTLS_SSL_EXT_ID_EXTENDED_MASTER_SECRET;
case MBEDTLS_TLS_EXT_RECORD_SIZE_LIMIT:
return MBEDTLS_SSL_EXT_ID_RECORD_SIZE_LIMIT;
case MBEDTLS_TLS_EXT_SESSION_TICKET:
return MBEDTLS_SSL_EXT_ID_SESSION_TICKET;
@ -635,7 +638,8 @@ static const char *extension_name_table[] = {
[MBEDTLS_SSL_EXT_ID_SUPPORTED_POINT_FORMATS] = "supported_point_formats",
[MBEDTLS_SSL_EXT_ID_ENCRYPT_THEN_MAC] = "encrypt_then_mac",
[MBEDTLS_SSL_EXT_ID_EXTENDED_MASTER_SECRET] = "extended_master_secret",
[MBEDTLS_SSL_EXT_ID_SESSION_TICKET] = "session_ticket"
[MBEDTLS_SSL_EXT_ID_SESSION_TICKET] = "session_ticket",
[MBEDTLS_SSL_EXT_ID_RECORD_SIZE_LIMIT] = "record_size_limit"
};
static unsigned int extension_type_table[] = {
@ -666,7 +670,8 @@ static unsigned int extension_type_table[] = {
[MBEDTLS_SSL_EXT_ID_SUPPORTED_POINT_FORMATS] = MBEDTLS_TLS_EXT_SUPPORTED_POINT_FORMATS,
[MBEDTLS_SSL_EXT_ID_ENCRYPT_THEN_MAC] = MBEDTLS_TLS_EXT_ENCRYPT_THEN_MAC,
[MBEDTLS_SSL_EXT_ID_EXTENDED_MASTER_SECRET] = MBEDTLS_TLS_EXT_EXTENDED_MASTER_SECRET,
[MBEDTLS_SSL_EXT_ID_SESSION_TICKET] = MBEDTLS_TLS_EXT_SESSION_TICKET
[MBEDTLS_SSL_EXT_ID_SESSION_TICKET] = MBEDTLS_TLS_EXT_SESSION_TICKET,
[MBEDTLS_SSL_EXT_ID_RECORD_SIZE_LIMIT] = MBEDTLS_TLS_EXT_RECORD_SIZE_LIMIT
};
const char *mbedtls_ssl_get_extension_name(unsigned int extension_type)

11
library/ssl_tls13_client.c
View File

@ -2173,6 +2173,17 @@ static int ssl_tls13_parse_encrypted_extensions(mbedtls_ssl_context *ssl,
break;
#endif /* MBEDTLS_SSL_EARLY_DATA */
#if defined(MBEDTLS_SSL_RECORD_SIZE_LIMIT)
case MBEDTLS_TLS_EXT_RECORD_SIZE_LIMIT:
MBEDTLS_SSL_DEBUG_MSG(3, ("found record_size_limit extension"));
ret = mbedtls_ssl_tls13_parse_record_size_limit_ext(ssl, p, p + extension_data_len);
return ret;
break;
#endif /* MBEDTLS_SSL_RECORD_SIZE_LIMIT */
default:
MBEDTLS_SSL_PRINT_EXT(
3, MBEDTLS_SSL_HS_ENCRYPTED_EXTENSIONS,

55
library/ssl_tls13_generic.c
View File

@ -1567,4 +1567,59 @@ int mbedtls_ssl_tls13_check_received_extension(
return MBEDTLS_ERR_SSL_UNSUPPORTED_EXTENSION;
}
#if defined(MBEDTLS_SSL_RECORD_SIZE_LIMIT)
/* From RFC 8449:
* The ExtensionData of the "record_size_limit" extension is
* RecordSizeLimit:
* uint16 RecordSizeLimit;
*/
MBEDTLS_CHECK_RETURN_CRITICAL
int mbedtls_ssl_tls13_parse_record_size_limit_ext(mbedtls_ssl_context *ssl,
const unsigned char *buf,
const unsigned char *end)
{
const ptrdiff_t extension_data_len = end - buf;
if (extension_data_len != 2) {
MBEDTLS_SSL_DEBUG_MSG(2,
("record_size_limit extension has invalid length: %td Bytes",
extension_data_len));
MBEDTLS_SSL_PEND_FATAL_ALERT(
MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER,
MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER);
return MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER;
}
const unsigned char *p = buf;
uint16_t record_size_limit;
MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, 2);
record_size_limit = MBEDTLS_GET_UINT16_BE(p, 0);
MBEDTLS_SSL_DEBUG_MSG(2, ("RecordSizeLimit: %u Bytes", record_size_limit));
/* RFC 8449 section 4
*
* Endpoints MUST NOT send a "record_size_limit" extension with a value
* smaller than 64. An endpoint MUST treat receipt of a smaller value
* as a fatal error and generate an "illegal_parameter" alert.
*/
if (record_size_limit < 64) {
MBEDTLS_SSL_PEND_FATAL_ALERT(
MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER,
MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER);
return MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER;
}
MBEDTLS_SSL_DEBUG_MSG(2,
(
"record_size_limit extension is still in development. Aborting handshake."));
MBEDTLS_SSL_PEND_FATAL_ALERT(
MBEDTLS_SSL_ALERT_MSG_UNSUPPORTED_EXT,
MBEDTLS_ERR_SSL_UNSUPPORTED_EXTENSION);
return MBEDTLS_ERR_SSL_UNSUPPORTED_EXTENSION;
}
#endif /* MBEDTLS_SSL_RECORD_SIZE_LIMIT */
#endif /* MBEDTLS_SSL_TLS_C && MBEDTLS_SSL_PROTO_TLS1_3 */

11
library/ssl_tls13_server.c
View File

@ -1585,6 +1585,17 @@ static int ssl_tls13_parse_client_hello(mbedtls_ssl_context *ssl,
break;
#endif /* MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_EPHEMERAL_ENABLED */
#if defined(MBEDTLS_SSL_RECORD_SIZE_LIMIT)
case MBEDTLS_TLS_EXT_RECORD_SIZE_LIMIT:
MBEDTLS_SSL_DEBUG_MSG(3, ("found record_size_limit extension"));
ret = mbedtls_ssl_tls13_parse_record_size_limit_ext(ssl, p, extension_data_end);
return ret;
break;
#endif /* MBEDTLS_SSL_RECORD_SIZE_LIMIT */
default:
MBEDTLS_SSL_PRINT_EXT(
3, MBEDTLS_SSL_HS_CLIENT_HELLO,