Revert r1.38 as it introduces use of a stack value post function return.

The deduplication is also not quite right - this will be revisited in due
course.

1 files changed, 86 insertions, 50 deletions

diff --git a/src/lib/libssl/ssl_tlsext.c b/src/lib/libssl/ssl_tlsext.c
index c74772f683..3502e5a721 100644
--- a/src/lib/libssl/ssl_tlsext.c
+++ b/src/lib/libssl/ssl_tlsext.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssl_tlsext.c,v 1.40 2019/01/31 08:11:55 tb Exp $ */
+/* $OpenBSD: ssl_tlsext.c,v 1.41 2019/02/03 14:09:58 jsing Exp $ */
 /*
  * Copyright (c) 2016, 2017, 2019 Joel Sing <jsing@openbsd.org>
  * Copyright (c) 2017 Doug Hogan <doug@openbsd.org>
@@ -25,24 +25,6 @@
 #include "ssl_sigalgs.h"
 #include "ssl_tlsext.h"
 
-
-static int
-tlsext_u16_prefixed_builder(CBB *parent, uint8_t *bytes, size_t len)
-{
-        CBB child;
-
-        if (!CBB_add_u16_length_prefixed(parent, &child))
-                return 0;
-
-        if (!CBB_add_bytes(&child, bytes, len))
-                return 0;
-
-        if (!CBB_flush(parent))
-                return 0;
-
-        return 1;
-}
-
 /*
  * Supported Application-Layer Protocol Negotiation - RFC 7301
  */
@@ -58,10 +40,19 @@ tlsext_alpn_client_needs(SSL *s)
 int
 tlsext_alpn_client_build(SSL *s, CBB *cbb)
 {
+        CBB protolist;
+
+        if (!CBB_add_u16_length_prefixed(cbb, &protolist))
+                return 0;
 
-        return (tlsext_u16_prefixed_builder(cbb,
-                s->internal->alpn_client_proto_list,
-                s->internal->alpn_client_proto_list_len));
+        if (!CBB_add_bytes(&protolist, s->internal->alpn_client_proto_list,
+            s->internal->alpn_client_proto_list_len))
+                return 0;
+
+        if (!CBB_flush(cbb))
+                return 0;
+
+        return 1;
 }
 
 int
@@ -1233,10 +1224,16 @@ tlsext_keyshare_client_needs(SSL *s)
 }
 
 int
-tlsext_keyshare_x25519_generate(SSL *s, CBB *keyshare)
+tlsext_keyshare_client_build(SSL *s, CBB *cbb)
 {
         uint8_t *public_key = NULL, *private_key = NULL;
-        CBB key_exchange;
+        CBB client_shares, key_exchange;
+
+        /* Generate and provide key shares. */
+        if (!CBB_add_u16_length_prefixed(cbb, &client_shares))
+                return 0;
+
+        /* XXX - other groups. */
 
         /* Generate X25519 key pair. */
         if ((public_key = malloc(X25519_KEY_LENGTH)) == NULL)
@@ -1246,13 +1243,16 @@ tlsext_keyshare_x25519_generate(SSL *s, CBB *keyshare)
         X25519_keypair(public_key, private_key);
 
         /* Add the group and serialize the public key. */
-        if (!CBB_add_u16(keyshare, tls1_ec_nid2curve_id(NID_X25519)))
+        if (!CBB_add_u16(&client_shares, tls1_ec_nid2curve_id(NID_X25519)))
                 goto err;
-        if (!CBB_add_u16_length_prefixed(keyshare, &key_exchange))
+        if (!CBB_add_u16_length_prefixed(&client_shares, &key_exchange))
                 goto err;
         if (!CBB_add_bytes(&key_exchange, public_key, X25519_KEY_LENGTH))
                 goto err;
 
+        if (!CBB_flush(cbb))
+                goto err;
+
         S3I(s)->hs_tls13.x25519_public = public_key;
         S3I(s)->hs_tls13.x25519_private = private_key;
 
@@ -1266,22 +1266,6 @@ tlsext_keyshare_x25519_generate(SSL *s, CBB *keyshare)
 }
 
 int
-tlsext_keyshare_client_build(SSL *s, CBB *cbb)
-{
-        CBB client_shares;
-
-        /* Generate and provide key shares. */
-        if (!CBB_add_u16_length_prefixed(cbb, &client_shares))
-                return 0;
-
-        if (!tlsext_keyshare_x25519_generate(s, &client_shares) ||
-            !CBB_flush(cbb))
-                return 0;
-
-        return (1);
-}
-
-int
 tlsext_keyshare_server_parse(SSL *s, CBS *cbs, int *alert)
 {
         CBS client_shares;
@@ -1343,15 +1327,43 @@ tlsext_keyshare_server_needs(SSL *s)
 int
 tlsext_keyshare_server_build(SSL *s, CBB *cbb)
 {
+        uint8_t *public_key = NULL, *private_key = NULL;
+        CBB key_exchange;
+
+        /* XXX deduplicate with client code */
+
         /* X25519 */
         if (S3I(s)->hs_tls13.x25519_peer_public == NULL)
                 return 0;
 
-        if (!tlsext_keyshare_x25519_generate(s, cbb) ||
-            !CBB_flush(cbb))
-                return 0;
+        /* Generate X25519 key pair. */
+        if ((public_key = malloc(X25519_KEY_LENGTH)) == NULL)
+                goto err;
+        if ((private_key = malloc(X25519_KEY_LENGTH)) == NULL)
+                goto err;
+        X25519_keypair(public_key, private_key);
+
+        /* Add the group and serialize the public key. */
+        if (!CBB_add_u16(cbb, tls1_ec_nid2curve_id(NID_X25519)))
+                goto err;
+        if (!CBB_add_u16_length_prefixed(cbb, &key_exchange))
+                goto err;
+        if (!CBB_add_bytes(&key_exchange, public_key, X25519_KEY_LENGTH))
+                goto err;
+
+        if (!CBB_flush(cbb))
+                goto err;
+
+        S3I(s)->hs_tls13.x25519_public = public_key;
+        S3I(s)->hs_tls13.x25519_private = private_key;
 
         return 1;
+
+ err:
+        freezero(public_key, X25519_KEY_LENGTH);
+        freezero(private_key, X25519_KEY_LENGTH);
+
+        return 0;
 }
 
 int
@@ -1528,8 +1540,19 @@ tlsext_cookie_client_needs(SSL *s)
 int
 tlsext_cookie_client_build(SSL *s, CBB *cbb)
 {
-        return (tlsext_u16_prefixed_builder(cbb,
-            S3I(s)->hs_tls13.cookie, S3I(s)->hs_tls13.cookie_len));
+        CBB cookie;
+
+        if (!CBB_add_u16_length_prefixed(cbb, &cookie))
+                return 0;
+
+        if (!CBB_add_bytes(&cookie, S3I(s)->hs_tls13.cookie,
+            S3I(s)->hs_tls13.cookie_len))
+                return 0;
+
+        if (!CBB_flush(cbb))
+                return 0;
+
+        return 1;
 }
 
 int
@@ -1581,8 +1604,21 @@ tlsext_cookie_server_needs(SSL *s)
 int
 tlsext_cookie_server_build(SSL *s, CBB *cbb)
 {
-        return (tlsext_u16_prefixed_builder(cbb,
-            S3I(s)->hs_tls13.cookie, S3I(s)->hs_tls13.cookie_len));
+        CBB cookie;
+
+        /* XXX deduplicate with client code */
+
+        if (!CBB_add_u16_length_prefixed(cbb, &cookie))
+                return 0;
+
+        if (!CBB_add_bytes(&cookie, S3I(s)->hs_tls13.cookie,
+            S3I(s)->hs_tls13.cookie_len))
+                return 0;
+
+        if (!CBB_flush(cbb))
+                return 0;
+
+        return 1;
 }
 
 int
@@ -1840,7 +1876,7 @@ tlsext_funcs(struct tls_extension *tlsext, int is_server)
         if (is_server)
                 return &tlsext->server;
 
-        return &tlsext->client;
+        return &tlsext->client; 
 }
 
 static int