From mboxrd@z Thu Jan 1 00:00:00 1970 From: Steffen Klassert Subject: [PATCH 6/8] xfrm: Fix stack-out-of-bounds with misconfigured transport mode policies. Date: Fri, 22 Dec 2017 10:44:59 +0100 Message-ID: <20171222094501.23345-7-steffen.klassert@secunet.com> References: <20171222094501.23345-1-steffen.klassert@secunet.com> Mime-Version: 1.0 Content-Type: text/plain Cc: Herbert Xu , Steffen Klassert , To: David Miller Return-path: Received: from a.mx.secunet.com ([62.96.220.36]:43788 "EHLO a.mx.secunet.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757799AbdLVJpQ (ORCPT ); Fri, 22 Dec 2017 04:45:16 -0500 In-Reply-To: <20171222094501.23345-1-steffen.klassert@secunet.com> Sender: netdev-owner@vger.kernel.org List-ID: On policies with a transport mode template, we pass the addresses from the flowi to xfrm_state_find(), assuming that the IP addresses (and address family) don't change during transformation. Unfortunately our policy template validation is not strict enough. It is possible to configure policies with transport mode template where the address family of the template does not match the selectors address family. This lead to stack-out-of-bound reads because we compare arddesses of the wrong family. Fix this by refusing such a configuration, address family can not change on transport mode. We use the assumption that, on transport mode, the first templates address family must match the address family of the policy selector. Subsequent transport mode templates must mach the address family of the previous template. Signed-off-by: Steffen Klassert --- net/xfrm/xfrm_user.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c index ff58c37469d6..bdb48e5dba04 100644 --- a/net/xfrm/xfrm_user.c +++ b/net/xfrm/xfrm_user.c @@ -1419,11 +1419,14 @@ static void copy_templates(struct xfrm_policy *xp, struct xfrm_user_tmpl *ut, static int validate_tmpl(int nr, struct xfrm_user_tmpl *ut, u16 family) { + u16 prev_family; int i; if (nr > XFRM_MAX_DEPTH) return -EINVAL; + prev_family = family; + for (i = 0; i < nr; i++) { /* We never validated the ut->family value, so many * applications simply leave it at zero. The check was @@ -1435,6 +1438,12 @@ static int validate_tmpl(int nr, struct xfrm_user_tmpl *ut, u16 family) if (!ut[i].family) ut[i].family = family; + if ((ut[i].mode == XFRM_MODE_TRANSPORT) && + (ut[i].family != prev_family)) + return -EINVAL; + + prev_family = ut[i].family; + switch (ut[i].family) { case AF_INET: break; -- 2.14.1