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tls13: srv: Enforce maximum size of early data

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Signed-off-by: Ronald Cron <ronald.cron@arm.com>
This commit is contained in:
Ronald Cron 2024-02-22 10:22:09 +01:00
parent c286519747
commit 8571804382
3 changed files with 49 additions and 8 deletions
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3
library/ssl_misc.h
View File

@ -2150,6 +2150,9 @@ int mbedtls_ssl_tls13_write_early_data_ext(mbedtls_ssl_context *ssl,
unsigned char *buf,
const unsigned char *end,
size_t *out_len);
int mbedtls_ssl_tls13_check_early_data_len(mbedtls_ssl_context *ssl,
size_t early_data_len);
#endif /* MBEDTLS_SSL_EARLY_DATA */
#endif /* MBEDTLS_SSL_PROTO_TLS1_3 */

41
library/ssl_tls13_generic.c
View File

@ -1454,6 +1454,47 @@ int mbedtls_ssl_tls13_write_early_data_ext(mbedtls_ssl_context *ssl,
return 0;
}
#if defined(MBEDTLS_SSL_SRV_C)
int mbedtls_ssl_tls13_check_early_data_len(mbedtls_ssl_context *ssl,
size_t early_data_len)
{
uint32_t uint32_early_data_len = (uint32_t) early_data_len;
/*
* This function should be called only while an handshake is in progress
* and thus a session under negotiation. Add a sanity check to detect a
* misuse.
*/
if (ssl->session_negotiate == NULL) {
return MBEDTLS_ERR_SSL_INTERNAL_ERROR;
}
/* RFC 8446 section 4.6.1
*
* A server receiving more than max_early_data_size bytes of 0-RTT data
* SHOULD terminate the connection with an "unexpected_message" alert.
*/
if (uint32_early_data_len >
(ssl->session_negotiate->max_early_data_size -
ssl->early_data_count)) {
MBEDTLS_SSL_DEBUG_MSG(
2, ("EarlyData: Too many early data received, %u > %u",
ssl->early_data_count + uint32_early_data_len,
ssl->session_negotiate->max_early_data_size));
MBEDTLS_SSL_PEND_FATAL_ALERT(
MBEDTLS_SSL_ALERT_MSG_UNEXPECTED_MESSAGE,
MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE);
return MBEDTLS_ERR_SSL_UNEXPECTED_MESSAGE;
}
ssl->early_data_count += uint32_early_data_len;
return 0;
}
#endif /* MBEDTLS_SSL_SRV_C */
#endif /* MBEDTLS_SSL_EARLY_DATA */
/* Reset SSL context and update hash for handling HRR.

13
library/ssl_tls13_server.c
View File

@ -2913,17 +2913,14 @@ static int ssl_tls13_end_of_early_data_coordinate(mbedtls_ssl_context *ssl)
}
if (ssl->in_msgtype == MBEDTLS_SSL_MSG_APPLICATION_DATA) {
MBEDTLS_SSL_DEBUG_MSG(3, ("Received early data"));
/* RFC 8446 section 4.6.1
*
* A server receiving more than max_early_data_size bytes of 0-RTT data
* SHOULD terminate the connection with an "unexpected_message" alert.
*
* TODO: Add received data size check here.
*/
if (ssl->in_offt == NULL) {
MBEDTLS_SSL_DEBUG_MSG(3, ("Received early data"));
/* Set the reading pointer */
ssl->in_offt = ssl->in_msg;
ret = mbedtls_ssl_tls13_check_early_data_len(ssl, ssl->in_msglen);
if (ret != 0) {
return ret;
}
}
return SSL_GOT_EARLY_DATA;
}