From mboxrd@z Thu Jan 1 00:00:00 1970 From: "=?UTF-8?q?Maciej=20=C5=BBenczykowski?=" Subject: [PATCH] net-xfrm: add build time cfg option to PF_KEY SHA256 to use RFC4868-compliant truncation Date: Tue, 16 Oct 2018 01:06:34 -0700 Message-ID: <20181016080634.139776-1-zenczykowski@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT Cc: netdev@vger.kernel.org, Lorenzo Colitti To: "=?UTF-8?q?Maciej=20=C5=BBenczykowski?=" , "David S . Miller" , Steffen Klassert , Herbert Xu Return-path: Received: from mail-io1-f73.google.com ([209.85.166.73]:53599 "EHLO mail-io1-f73.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726729AbeJPPz6 (ORCPT ); Tue, 16 Oct 2018 11:55:58 -0400 Received: by mail-io1-f73.google.com with SMTP id t22-v6so20915742ioc.20 for ; Tue, 16 Oct 2018 01:06:45 -0700 (PDT) Sender: netdev-owner@vger.kernel.org List-ID: From: Maciej Żenczykowski When using the PF_KEY interface, SHA-256 hashes are hardcoded to use 96-bit truncation. This is a violation of RFC4868, which specifies 128-bit truncation. We cannot fix this without introducing backwards compatibility concerns unless we make it an optional build time setting (defaulting to no). Android will default to yes instead of carrying an Android specific one line patch. While the PF_KEY interface is deprecated in favour of netlink XFRM (which allows the app to specify an arbitrary truncation length), changing the PF_KEY truncation length from 96 to 128 allows PF_KEY apps such as racoon to work with standards-compliant VPN servers. Cc: Lorenzo Colitti Signed-off-by: Maciej Żenczykowski --- net/xfrm/Kconfig | 10 ++++++++++ net/xfrm/xfrm_algo.c | 4 ++++ 2 files changed, 14 insertions(+) diff --git a/net/xfrm/Kconfig b/net/xfrm/Kconfig index 4a9ee2d83158..0ede7e81a5d3 100644 --- a/net/xfrm/Kconfig +++ b/net/xfrm/Kconfig @@ -15,6 +15,16 @@ config XFRM_ALGO select XFRM select CRYPTO +config XFRM_HMAC_SHA256_RFC4868 + bool "Strict RFC4868 hmac(sha256) 128-bit truncation" + depends on XFRM_ALGO + default n + ---help--- + Support strict RFC4868 hmac(sha256) 128-bit truncation + (default on Android) instead of the default 96-bit Linux truncation. + + If unsure, say N. + config XFRM_USER tristate "Transformation user configuration interface" depends on INET diff --git a/net/xfrm/xfrm_algo.c b/net/xfrm/xfrm_algo.c index 44ac85fe2bc9..a70391fb2c1e 100644 --- a/net/xfrm/xfrm_algo.c +++ b/net/xfrm/xfrm_algo.c @@ -241,7 +241,11 @@ static struct xfrm_algo_desc aalg_list[] = { .uinfo = { .auth = { +#if IS_ENABLED(CONFIG_XFRM_HMAC_SHA256_RFC4868) + .icv_truncbits = 128, +#else .icv_truncbits = 96, +#endif .icv_fullbits = 256, } }, -- 2.19.1.331.ge82ca0e54c-goog