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Merge pull request #8526 from yanrayw/issue/7011/send_record_size_limit_ext

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TLS1.3: SRV/CLI: add support for sending Record Size Limit extension
This commit is contained in:
Tom Cosgrove
2024-01-12 13:39:15 +00:00
committed by GitHub
parent 3519cfb3d8 f0ccf46713
commit f1ba1933cf
10 changed files with 294 additions and 49 deletions
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8
library/ssl_misc.h
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@ -2704,12 +2704,18 @@ int mbedtls_ssl_parse_server_name_ext(mbedtls_ssl_context *ssl,
#if defined(MBEDTLS_SSL_RECORD_SIZE_LIMIT)
#define MBEDTLS_SSL_RECORD_SIZE_LIMIT_EXTENSION_DATA_LENGTH (2)
#define MBEDTLS_SSL_RECORD_SIZE_LIMIT_MIN (64)
#define MBEDTLS_SSL_RECORD_SIZE_LIMIT_MIN (64) /* As defined in RFC 8449 */
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);
MBEDTLS_CHECK_RETURN_CRITICAL
int mbedtls_ssl_tls13_write_record_size_limit_ext(mbedtls_ssl_context *ssl,
unsigned char *buf,
const unsigned char *end,
size_t *out_len);
#endif /* MBEDTLS_SSL_RECORD_SIZE_LIMIT */
#if defined(MBEDTLS_SSL_ALPN)

18
library/ssl_tls.c
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@ -3521,15 +3521,15 @@ int mbedtls_ssl_get_max_out_record_payload(const mbedtls_ssl_context *ssl)
if (ssl->transform_out != NULL &&
ssl->transform_out->tls_version == MBEDTLS_SSL_VERSION_TLS1_3) {
/* RFC 8449, section 4:
*
* This value [record_size_limit] is the length of the plaintext
* of a protected record.
* The value includes the content type and padding added in TLS 1.3
* (that is, the complete length of TLSInnerPlaintext).
*
* Thus, round down to a multiple of MBEDTLS_SSL_CID_TLS1_3_PADDING_GRANULARITY
* and subtract 1 (for the content type that will be added later)
/*
* In TLS 1.3 case, when records are protected, `max_len` as computed
* above is the maximum length of the TLSInnerPlaintext structure that
* along the plaintext payload contains the inner content type (one byte)
* and some zero padding. Given the algorithm used for padding
* in mbedtls_ssl_encrypt_buf(), compute the maximum length for
* the plaintext payload. Round down to a multiple of
* MBEDTLS_SSL_CID_TLS1_3_PADDING_GRANULARITY and
* subtract 1.
*/
max_len = ((max_len / MBEDTLS_SSL_CID_TLS1_3_PADDING_GRANULARITY) *
MBEDTLS_SSL_CID_TLS1_3_PADDING_GRANULARITY) - 1;

9
library/ssl_tls13_client.c
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@ -1160,6 +1160,15 @@ int mbedtls_ssl_tls13_write_client_hello_exts(mbedtls_ssl_context *ssl,
}
p += ext_len;
#if defined(MBEDTLS_SSL_RECORD_SIZE_LIMIT)
ret = mbedtls_ssl_tls13_write_record_size_limit_ext(
ssl, p, end, &ext_len);
if (ret != 0) {
return ret;
}
p += ext_len;
#endif
#if defined(MBEDTLS_SSL_TLS1_3_KEY_EXCHANGE_MODE_SOME_EPHEMERAL_ENABLED)
if (mbedtls_ssl_conf_tls13_is_some_ephemeral_enabled(ssl)) {
ret = ssl_tls13_write_key_share_ext(ssl, p, end, &ext_len);

33
library/ssl_tls13_generic.c
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@ -1698,6 +1698,7 @@ int mbedtls_ssl_tls13_check_received_extension(
}
#if defined(MBEDTLS_SSL_RECORD_SIZE_LIMIT)
/* RFC 8449, section 4:
*
* The ExtensionData of the "record_size_limit" extension is
@ -1738,6 +1739,8 @@ int mbedtls_ssl_tls13_parse_record_size_limit_ext(mbedtls_ssl_context *ssl,
* as a fatal error and generate an "illegal_parameter" alert.
*/
if (record_size_limit < MBEDTLS_SSL_RECORD_SIZE_LIMIT_MIN) {
MBEDTLS_SSL_DEBUG_MSG(1, ("Invalid record size limit : %u Bytes",
record_size_limit));
MBEDTLS_SSL_PEND_FATAL_ALERT(
MBEDTLS_SSL_ALERT_MSG_ILLEGAL_PARAMETER,
MBEDTLS_ERR_SSL_ILLEGAL_PARAMETER);
@ -1749,6 +1752,36 @@ int mbedtls_ssl_tls13_parse_record_size_limit_ext(mbedtls_ssl_context *ssl,
return 0;
}
MBEDTLS_CHECK_RETURN_CRITICAL
int mbedtls_ssl_tls13_write_record_size_limit_ext(mbedtls_ssl_context *ssl,
unsigned char *buf,
const unsigned char *end,
size_t *out_len)
{
unsigned char *p = buf;
*out_len = 0;
MBEDTLS_STATIC_ASSERT(MBEDTLS_SSL_IN_CONTENT_LEN >= MBEDTLS_SSL_RECORD_SIZE_LIMIT_MIN,
"MBEDTLS_SSL_IN_CONTENT_LEN is less than the "
"minimum record size limit");
MBEDTLS_SSL_CHK_BUF_PTR(p, end, 6);
MBEDTLS_PUT_UINT16_BE(MBEDTLS_TLS_EXT_RECORD_SIZE_LIMIT, p, 0);
MBEDTLS_PUT_UINT16_BE(MBEDTLS_SSL_RECORD_SIZE_LIMIT_EXTENSION_DATA_LENGTH,
p, 2);
MBEDTLS_PUT_UINT16_BE(MBEDTLS_SSL_IN_CONTENT_LEN, p, 4);
*out_len = 6;
MBEDTLS_SSL_DEBUG_MSG(2, ("Sent RecordSizeLimit: %d Bytes",
MBEDTLS_SSL_IN_CONTENT_LEN));
mbedtls_ssl_tls13_set_hs_sent_ext_mask(ssl, MBEDTLS_TLS_EXT_RECORD_SIZE_LIMIT);
return 0;
}
#endif /* MBEDTLS_SSL_RECORD_SIZE_LIMIT */
#endif /* MBEDTLS_SSL_TLS_C && MBEDTLS_SSL_PROTO_TLS1_3 */

11
library/ssl_tls13_server.c
View File

@ -2540,6 +2540,17 @@ static int ssl_tls13_write_encrypted_extensions_body(mbedtls_ssl_context *ssl,
}
#endif /* MBEDTLS_SSL_EARLY_DATA */
#if defined(MBEDTLS_SSL_RECORD_SIZE_LIMIT)
if (ssl->handshake->received_extensions & MBEDTLS_SSL_EXT_MASK(RECORD_SIZE_LIMIT)) {
ret = mbedtls_ssl_tls13_write_record_size_limit_ext(
ssl, p, end, &output_len);
if (ret != 0) {
return ret;
}
p += output_len;
}
#endif
extensions_len = (p - p_extensions_len) - 2;
MBEDTLS_PUT_UINT16_BE(extensions_len, p_extensions_len, 0);