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Merge pull request #9244 from waleed-elmelegy-arm/fix-tls13_parse_client_hello-issue

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Fix issue in handling legacy_compression_methods in ssl_tls13_parse_client_hello()
This commit is contained in:
Gilles Peskine 2024-08-22 18:56:27 +00:00 committed by GitHub
commit 805ac15e2d
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3 changed files with 26 additions and 4 deletions
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6
ChangeLog.d/fix-legacy-compression-issue.txt Normal file
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@ -0,0 +1,6 @@
Bugfix
* Fixes an issue where some TLS 1.2 clients could not connect to an
Mbed TLS 3.6.0 server, due to incorrect handling of
legacy_compression_methods in the ClientHello.
fixes #8995, #9243.

12
library/ssl_tls13_server.c
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@ -1355,19 +1355,23 @@ static int ssl_tls13_parse_client_hello(mbedtls_ssl_context *ssl,
* compression methods and the length of the extensions.
*
* cipher_suites cipher_suites_len bytes
* legacy_compression_methods 2 bytes
* extensions_len 2 bytes
* legacy_compression_methods length 1 byte
*/
MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, cipher_suites_len + 2 + 2);
MBEDTLS_SSL_CHK_BUF_READ_PTR(p, end, cipher_suites_len + 1);
p += cipher_suites_len;
cipher_suites_end = p;
/* Check if we have enough data for legacy_compression_methods
* and the length of the extensions (2 bytes).
*/
MBEDTLS_SSL_CHK_BUF_READ_PTR(p + 1, end, p[0] + 2);
/*
* Search for the supported versions extension and parse it to determine
* if the client supports TLS 1.3.
*/
ret = mbedtls_ssl_tls13_is_supported_versions_ext_present_in_exts(
ssl, p + 2, end,
ssl, p + 1 + p[0], end,
&supported_versions_data, &supported_versions_data_end);
if (ret < 0) {
MBEDTLS_SSL_DEBUG_RET(1,

12
tests/ssl-opt.sh
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@ -14142,6 +14142,18 @@ run_test "TLS 1.3: no HRR in case of PSK key exchange mode" \
-c "Selected key exchange mode: psk$" \
-c "HTTP/1.0 200 OK"
# Legacy_compression_methods testing
requires_gnutls
requires_config_enabled MBEDTLS_SSL_SRV_C
requires_config_enabled MBEDTLS_SSL_PROTO_TLS1_2
run_test "TLS 1.2 ClientHello indicating support for deflate compression method" \
"$P_SRV debug_level=3" \
"$G_CLI --priority=NORMAL:-VERS-ALL:+VERS-TLS1.2:+COMP-DEFLATE localhost" \
0 \
-c "Handshake was completed" \
-s "dumping .client hello, compression. (2 bytes)"
# Test heap memory usage after handshake
requires_config_enabled MBEDTLS_SSL_PROTO_TLS1_2
requires_config_enabled MBEDTLS_MEMORY_DEBUG