Copy custom extension flags in a call to SSL_set_SSL_CTX()

The function SSL_set_SSL_CTX() can be used to swap the SSL_CTX used for
a connection as part of an SNI callback. One result of this is that the
s->cert structure is replaced. However this structure contains information
about any custom extensions that have been loaded. In particular flags are
set indicating whether a particular extension has been received in the
ClientHello. By replacing the s->cert structure we lose the custom
extension flag values, and it appears as if a client has not sent those
extensions.

SSL_set_SSL_CTX() should copy any flags for custom extensions that appear
in both the old and the new cert structure.

Fixes #2180

Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3425)

1 files changed, 6 insertions, 0 deletions

diff --git a/ssl/ssl_lib.c b/ssl/ssl_lib.c
index d1a1f027d9..a12800d6d3 100644
--- a/ssl/ssl_lib.c
+++ b/ssl/ssl_lib.c
@@ -3596,6 +3596,12 @@ SSL_CTX *SSL_set_SSL_CTX(SSL *ssl, SSL_CTX *ctx)
     if (new_cert == NULL) {
         return NULL;
     }
+
+    if (!custom_exts_copy_flags(&new_cert->custext, &ssl->cert->custext)) {
+        ssl_cert_free(new_cert);
+        return NULL;
+    }
+
     ssl_cert_free(ssl->cert);
     ssl->cert = new_cert;