Add sigalgs for server side to enable client certificate processing

in tls 1.3

Will be used in a follow on commit to enable tls1.3 client certificates

ok jsing@

1 files changed, 34 insertions, 5 deletions

diff --git a/src/lib/libssl/ssl_tlsext.c b/src/lib/libssl/ssl_tlsext.c
index 24f2bd5022..5cebd1d630 100644
--- a/src/lib/libssl/ssl_tlsext.c
+++ b/src/lib/libssl/ssl_tlsext.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssl_tlsext.c,v 1.56 2020/01/25 12:37:06 jsing Exp $ */
+/* $OpenBSD: ssl_tlsext.c,v 1.57 2020/01/26 03:29:30 beck Exp $ */
 /*
  * Copyright (c) 2016, 2017, 2019 Joel Sing <jsing@openbsd.org>
  * Copyright (c) 2017 Doug Hogan <doug@openbsd.org>
@@ -571,20 +571,49 @@ tlsext_sigalgs_server_parse(SSL *s, CBS *cbs, int *alert)
 int
 tlsext_sigalgs_server_needs(SSL *s)
 {
-        return 0;
+        return (s->version >= TLS1_3_VERSION);
 }
 
 int
 tlsext_sigalgs_server_build(SSL *s, CBB *cbb)
 {
-        return 0;
+        uint16_t *tls_sigalgs = tls12_sigalgs;
+        size_t tls_sigalgs_len = tls12_sigalgs_len;
+        CBB sigalgs;
+
+        if (s->version >= TLS1_3_VERSION) {
+                tls_sigalgs = tls13_sigalgs;
+                tls_sigalgs_len = tls13_sigalgs_len;
+        }
+
+        if (!CBB_add_u16_length_prefixed(cbb, &sigalgs))
+                return 0;
+
+        if (!ssl_sigalgs_build(&sigalgs, tls_sigalgs, tls_sigalgs_len))
+                return 0;
+
+        if (!CBB_flush(cbb))
+                return 0;
+
+        return 1;
 }
 
 int
 tlsext_sigalgs_client_parse(SSL *s, CBS *cbs, int *alert)
 {
-        /* As per the RFC, servers must not send this extension. */
-        return 0;
+        CBS sigalgs;
+
+        if (s->version < TLS1_3_VERSION)
+                return 0;
+
+        if (!CBS_get_u16_length_prefixed(cbs, &sigalgs))
+                return 0;
+        if (CBS_len(&sigalgs) % 2 != 0 || CBS_len(&sigalgs) > 64)
+                return 0;
+        if (!CBS_stow(&sigalgs, &S3I(s)->hs.sigalgs, &S3I(s)->hs.sigalgs_len))
+                return 0;
+
+        return 1;
 }
 
 /*