Remove cipher from SSL_SESSION.

For a long time SSL_SESSION has had both a cipher ID and a pointer to
an SSL_CIPHER (and not both are guaranteed to be populated). There is also
a pointer to an SSL_CIPHER in the SSL_HANDSHAKE that denotes the cipher
being used for this connection. Some code has been using the cipher from
SSL_SESSION and some code has been using the cipher from SSL_HANDSHAKE.

Remove cipher from SSL_SESSION and use the version in SSL_HANDSHAKE
everywhere. If resuming from a session then we need to use the SSL_SESSION
cipher ID to set the SSL_HANDSHAKE cipher. And we still need to ensure that
we update the cipher ID in the SSL_SESSION whenever the SSL_HANDSHAKE
cipher changes (this only occurs in a few places).

ok tb@

1 files changed, 5 insertions, 6 deletions

diff --git a/src/lib/libssl/ssl_clnt.c b/src/lib/libssl/ssl_clnt.c
index 6cf0ee4a4a..7b2e05d23d 100644
--- a/src/lib/libssl/ssl_clnt.c
+++ b/src/lib/libssl/ssl_clnt.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssl_clnt.c,v 1.166 2024/07/19 08:56:17 jsing Exp $ */
+/* $OpenBSD: ssl_clnt.c,v 1.167 2024/07/20 04:04:23 jsing Exp $ */
 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
  * All rights reserved.
  *
@@ -481,7 +481,7 @@ ssl3_connect(SSL *s)
 
                         s->s3->hs.state = SSL3_ST_CW_FINISHED_A;
                         s->init_num = 0;
-                        s->session->cipher = s->s3->hs.cipher;
+                        s->session->cipher_id = s->s3->hs.cipher->id;
 
                         if (!tls1_setup_key_block(s)) {
                                 ret = -1;
@@ -946,8 +946,8 @@ ssl3_get_server_hello(SSL *s)
                  * 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 =
+                if ((s->s3->hs.cipher = pref_cipher) == NULL)
+                        s->s3->hs.cipher =
                             ssl3_get_cipher_by_value(cipher_suite);
                 s->s3->flags |= SSL3_FLAGS_CCS_OK;
         }
@@ -1016,14 +1016,13 @@ ssl3_get_server_hello(SSL *s)
          * and/or cipher_id values may not be set. Make sure that
          * cipher_id is set and use it for comparison.
          */
-        if (s->session->cipher)
-                s->session->cipher_id = s->session->cipher->id;
         if (s->hit && (s->session->cipher_id != cipher->id)) {
                 al = SSL_AD_ILLEGAL_PARAMETER;
                 SSLerror(s, SSL_R_OLD_SESSION_CIPHER_NOT_RETURNED);
                 goto fatal_err;
         }
         s->s3->hs.cipher = cipher;
+        s->session->cipher_id = cipher->id;
 
         if (!tls1_transcript_hash_init(s))
                 goto err;