[Openvpn-devel] [PATCH v3] Fix compatibility with mbedTLS 2.28.10+ and 3.6.3+

[Gert D. <ge...@gr...>]

From: Frank Lichtenheld <fr...@li...>

>From release notes:
In TLS clients, if mbedtls_ssl_set_hostname() has not been called,
mbedtls_ssl_handshake() now fails with
MBEDTLS_ERR_SSL_CERTIFICATE_VERIFICATION_WITHOUT_HOSTNAME
if certificate-based authentication of the server is attempted.
This is because authenticating a server without knowing what name
to expect is usually insecure. To restore the old behavior, either
call mbedtls_ssl_set_hostname() with NULL as the hostname [...]

Change-Id: I8bbb6ffdac7d0029dbf3c13e62c11b61813c15ef
Signed-off-by: Frank Lichtenheld <fr...@li...>
Acked-by: MaxF <ma...@ma...>
---

This change was reviewed on Gerrit and approved by at least one
developer. I request to merge it to master.

Gerrit URL: https://gerrit.openvpn.net/c/openvpn/+/918
This mail reflects revision 3 of this Change.

Acked-by according to Gerrit (reflected above):
MaxF <ma...@ma...>

        
diff --git a/src/openvpn/ssl_mbedtls.c b/src/openvpn/ssl_mbedtls.c
index 92b52fe..e15c391 100644
--- a/src/openvpn/ssl_mbedtls.c
+++ b/src/openvpn/ssl_mbedtls.c
@@ -1246,6 +1246,10 @@
     ALLOC_OBJ_CLEAR(ks_ssl->ctx, mbedtls_ssl_context);
     mbedtls_ssl_init(ks_ssl->ctx);
     mbed_ok(mbedtls_ssl_setup(ks_ssl->ctx, ks_ssl->ssl_config));
+    /* We do verification in our own callback depending on the
+     * exact configuration. We do not rely on the default hostname
+     * verification. */
+    ASSERT(mbed_ok(mbedtls_ssl_set_hostname(ks_ssl->ctx, NULL)));
 
 #if HAVE_MBEDTLS_SSL_SET_EXPORT_KEYS_CB
     /* Initialize keying material exporter, new style. */