Fix another return 0 bug in SSL_shutdown()

If tls13_recod_layer_send_pending() returns TLS13_IO_EOF, we will
bubble this up to the caller via tls13_legacy_return_code(), which
translates TLS13_IO_EOF to 0. This can happen if we have pending
post handshake-handshake data and the peer closes the pipe.

Presumably tls13_legacy_shutdown() should be rewritten yet again.

ok jsing

1 files changed, 8 insertions, 6 deletions

diff --git a/src/lib/libssl/tls13_legacy.c b/src/lib/libssl/tls13_legacy.c
index 7327311c7b..a62e936ccb 100644
--- a/src/lib/libssl/tls13_legacy.c
+++ b/src/lib/libssl/tls13_legacy.c
@@ -1,4 +1,4 @@
-/*      $OpenBSD: tls13_legacy.c,v 1.34 2022/01/25 14:51:54 tb Exp $ */
+/*      $OpenBSD: tls13_legacy.c,v 1.35 2022/01/25 15:00:09 tb Exp $ */
 /*
  * Copyright (c) 2018, 2019 Joel Sing <jsing@openbsd.org>
  *
@@ -483,9 +483,9 @@ tls13_legacy_shutdown(SSL *ssl)
         ssize_t ret;
 
         /*
-         * We need to return 0 when we have sent a close-notify but have not
-         * yet received one. We return 1 only once we have sent and received
-         * close-notify alerts. All other cases return -1 and set internal
+         * We need to return 0 at the point that we have completed sending a
+         * close-notify. We return 1 when we have sent and received close-notify
+         * alerts. All other cases, including EOF, return -1 and set internal
          * state appropriately.
          */
         if (ctx == NULL || ssl->internal->quiet_shutdown) {
@@ -501,8 +501,10 @@ tls13_legacy_shutdown(SSL *ssl)
                             TLS13_ALERT_CLOSE_NOTIFY)) < 0)
                                 return tls13_legacy_return_code(ssl, ret);
                 }
-                if ((ret = tls13_record_layer_send_pending(ctx->rl)) !=
-                    TLS13_IO_SUCCESS)
+                ret = tls13_record_layer_send_pending(ctx->rl);
+                if (ret == TLS13_IO_EOF)
+                        return -1;
+                if (ret != TLS13_IO_SUCCESS)
                         return tls13_legacy_return_code(ssl, ret);
         } else if (!ctx->close_notify_recv) {
                 /*