denozord/strongswan-ext
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

libtls: Add downgrade protection for TLS 1.3 and TLS 1.2

Browse Source 
Section 4.1.3 in RFC 8446 defines a new downgrade protection mechanism
that also affects TLS 1.2.
This commit is contained in:
Pascal Knecht
2021-02-12 14:35:23 +01:00
committed by Tobias Brunner
parent a4a128bd2f
commit dc9f6c68df
4 changed files with 53 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/libtls/tls_server.c
+19 -1
View File
@@ -1,5 +1,5 @@
/*
* Copyright (C) 2020 Pascal Knecht
* Copyright (C) 2020-2021 Pascal Knecht
* HSR Hochschule fuer Technik Rapperswil
*
* Copyright (C) 2010 Martin Willi
@@ -338,6 +338,7 @@ static status_t process_client_hello(private_tls_server_t *this,
chunk_t extension_data = chunk_empty;
bio_reader_t *extensions, *extension;
tls_cipher_suite_t *suites;
tls_version_t original_version_max;
int count, i;
rng_t *rng;
@@ -456,6 +457,8 @@ static status_t process_client_hello(private_tls_server_t *this,
}
rng->destroy(rng);
original_version_max = this->tls->get_version_max(this->tls);
if (versions.len)
{
bio_reader_t *client_versions;
@@ -482,6 +485,21 @@ static status_t process_client_hello(private_tls_server_t *this,
this->client_version = version;
}
}
/* downgrade protection (see RFC 8446, section 4.1.3) */
if ((original_version_max == TLS_1_3 && version < TLS_1_3) ||
(original_version_max == TLS_1_2 && version < TLS_1_2))
{
chunk_t downgrade_protection = tls_downgrade_protection_tls11;
if (version == TLS_1_2)
{
downgrade_protection = tls_downgrade_protection_tls12;
}
memcpy(&this->server_random[24], downgrade_protection.ptr,
downgrade_protection.len);
}
if (!this->client_version)
{
DBG1(DBG_TLS, "proposed version %N not supported", tls_version_names,