From: Dmitry Belyavsky <beldmit@gmail.com>
Date: Mon, 19 Sep 2016 15:05:53 +0000 (+0100)
Subject: Avoid KCI attack for GOST
X-Git-Tag: OpenSSL_1_0_2i~2
X-Git-Url: https://git.librecmc.org/?a=commitdiff_plain;h=92c8d6ae0d741fdca3b72baf627d16908dae64ce;p=oweals%2Fopenssl.git

Avoid KCI attack for GOST

Russian GOST ciphersuites are vulnerable to the KCI attack because they use
long-term keys to establish the connection when ssl client authorization is
on. This change brings the GOST implementation into line with the latest
specs in order to avoid the attack. It should not break backwards
compatibility.

Reviewed-by: Rich Salz <rsalz@openssl.org>
Reviewed-by: Richard Levitte <levitte@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
---

diff --git a/ssl/s3_clnt.c b/ssl/s3_clnt.c
index d2afaa5b9f..218534734d 100644
--- a/ssl/s3_clnt.c
+++ b/ssl/s3_clnt.c
@@ -3013,19 +3013,6 @@ int ssl3_send_client_key_exchange(SSL *s)
                        ERR_R_INTERNAL_ERROR);
                 goto err;
             }
-            /*
-             * If we have client certificate, use its secret as peer key
-             */
-            if (s->s3->tmp.cert_req && s->cert->key->privatekey) {
-                if (EVP_PKEY_derive_set_peer
-                    (pkey_ctx, s->cert->key->privatekey) <= 0) {
-                    /*
-                     * If there was an error - just ignore it. Ephemeral key
-                     * * would be used
-                     */
-                    ERR_clear_error();
-                }
-            }
             /*
              * Compute shared IV and store it in algorithm-specific context
              * data
@@ -3072,12 +3059,6 @@ int ssl3_send_client_key_exchange(SSL *s)
                 n = msglen + 2;
             }
             memcpy(p, tmp, msglen);
-            /* Check if pubkey from client certificate was used */
-            if (EVP_PKEY_CTX_ctrl
-                (pkey_ctx, -1, -1, EVP_PKEY_CTRL_PEER_KEY, 2, NULL) > 0) {
-                /* Set flag "skip certificate verify" */
-                s->s3->flags |= TLS1_FLAGS_SKIP_CERT_VERIFY;
-            }
             EVP_PKEY_CTX_free(pkey_ctx);
             s->session->master_key_length =
                 s->method->ssl3_enc->generate_master_secret(s,