From: Matt Caswell <matt@openssl.org>
Date: Tue, 16 May 2017 11:04:00 +0000 (+0100)
Subject: Allow a missing sig algs extension if resuming
X-Git-Tag: OpenSSL_1_1_1-pre1~1496
X-Git-Url: https://git.librecmc.org/?a=commitdiff_plain;h=108d45df737f5b0a4842de02c3f8ff1b9b07306f;p=oweals%2Fopenssl.git

Allow a missing sig algs extension if resuming

The current TLSv1.3 spec says:

'If a server is authenticating via a certificate and the client has not
sent a "signature_algorithms" extension, then the server MUST abort the
handshake with a "missing_extension" alert (see Section 8.2).'

If we are resuming then we are not "authenticating via a certificate" but
we were still aborting with the missing_extension alert if sig algs was
missing.

This commit ensures that we only send the alert if we are not resuming.

Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3478)
---

diff --git a/ssl/statem/extensions.c b/ssl/statem/extensions.c
index fd76337564..68d8cea0bd 100644
--- a/ssl/statem/extensions.c
+++ b/ssl/statem/extensions.c
@@ -1081,7 +1081,7 @@ static int init_srtp(SSL *s, unsigned int context)
 
 static int final_sig_algs(SSL *s, unsigned int context, int sent, int *al)
 {
-    if (!sent && SSL_IS_TLS13(s)) {
+    if (!sent && SSL_IS_TLS13(s) && !s->hit) {
         *al = TLS13_AD_MISSING_EXTENSION;
         SSLerr(SSL_F_FINAL_SIG_ALGS, SSL_R_MISSING_SIGALGS_EXTENSION);
         return 0;