Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753623AbdFGXGK (ORCPT ); Wed, 7 Jun 2017 19:06:10 -0400 Received: from wtarreau.pck.nerim.net ([62.212.114.60]:50814 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753532AbdFGXF7 (ORCPT ); Wed, 7 Jun 2017 19:05:59 -0400 From: Willy Tarreau To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, linux@roeck-us.net Cc: Ryan Ware , Mimi Zohar , James Morris , "Jason A . Donenfeld" , Willy Tarreau Subject: [PATCH 3.10 003/250] EVM: Use crypto_memneq() for digest comparisons Date: Thu, 8 Jun 2017 00:56:29 +0200 Message-Id: <1496876436-32402-4-git-send-email-w@1wt.eu> X-Mailer: git-send-email 2.8.0.rc2.1.gbe9624a In-Reply-To: <1496876436-32402-1-git-send-email-w@1wt.eu> References: <1496876436-32402-1-git-send-email-w@1wt.eu> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1546 Lines: 44 From: Ryan Ware commit 613317bd212c585c20796c10afe5daaa95d4b0a1 upstream. This patch fixes vulnerability CVE-2016-2085. The problem exists because the vm_verify_hmac() function includes a use of memcmp(). Unfortunately, this allows timing side channel attacks; specifically a MAC forgery complexity drop from 2^128 to 2^12. This patch changes the memcmp() to the cryptographically safe crypto_memneq(). Reported-by: Xiaofei Rex Guo Signed-off-by: Ryan Ware Cc: stable@vger.kernel.org Signed-off-by: Mimi Zohar Signed-off-by: James Morris Cc: Jason A. Donenfeld Signed-off-by: Willy Tarreau --- security/integrity/evm/evm_main.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c index b980a6c..3db2bf1 100644 --- a/security/integrity/evm/evm_main.c +++ b/security/integrity/evm/evm_main.c @@ -20,6 +20,7 @@ #include #include #include +#include #include "evm.h" int evm_initialized; @@ -128,7 +129,7 @@ static enum integrity_status evm_verify_hmac(struct dentry *dentry, xattr_value_len, calc.digest); if (rc) break; - rc = memcmp(xattr_data->digest, calc.digest, + rc = crypto_memneq(xattr_data->digest, calc.digest, sizeof(calc.digest)); if (rc) rc = -EINVAL; -- 2.8.0.rc2.1.gbe9624a