Annotate issues with tls_session_secret_cb() related code.

2 files changed, 15 insertions, 2 deletions

diff --git a/src/lib/libssl/ssl_clnt.c b/src/lib/libssl/ssl_clnt.c
index feb29ee4a5..6cf0ee4a4a 100644
--- a/src/lib/libssl/ssl_clnt.c
+++ b/src/lib/libssl/ssl_clnt.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssl_clnt.c,v 1.165 2024/02/03 18:03:49 tb Exp $ */
+/* $OpenBSD: ssl_clnt.c,v 1.166 2024/07/19 08:56:17 jsing Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -941,6 +941,11 @@ ssl3_get_server_hello(SSL *s)
                 }
                 s->session->master_key_length = master_key_length;
 
+                /*
+                 * XXX - this appears to be completely broken. The
+                 * client cannot change the cipher at this stage,
+                 * as the server has already made a selection.
+                 */
                 if ((s->session->cipher = pref_cipher) == NULL)
                         s->session->cipher =
                             ssl3_get_cipher_by_value(cipher_suite);
diff --git a/src/lib/libssl/ssl_srvr.c b/src/lib/libssl/ssl_srvr.c
index d6b7de1efd..01155a8d6d 100644
--- a/src/lib/libssl/ssl_srvr.c
+++ b/src/lib/libssl/ssl_srvr.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssl_srvr.c,v 1.162 2024/07/19 08:54:31 jsing Exp $ */
+/* $OpenBSD: ssl_srvr.c,v 1.163 2024/07/19 08:56:17 jsing Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -1082,6 +1082,13 @@ ssl3_get_client_hello(SSL *s)
                 s->s3->hs.client_ciphers = ciphers;
                 ciphers = NULL;
 
+                /*
+                 * XXX - this allows the callback to use any client cipher and
+                 * completely ignore the server cipher list. We should ensure
+                 * that the pref_cipher is in both the client list and the
+                 * server list.
+                 */
+
                 /* Check if some cipher was preferred by the callback. */
                 if (pref_cipher == NULL)
                         pref_cipher = ssl3_choose_cipher(s, s->s3->hs.client_ciphers,
@@ -1093,6 +1100,7 @@ ssl3_get_client_hello(SSL *s)
                 }
                 s->session->cipher = pref_cipher;
 
+                /* XXX - why? */
                 sk_SSL_CIPHER_free(s->cipher_list);
                 s->cipher_list = sk_SSL_CIPHER_dup(s->s3->hs.client_ciphers);
         }