Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756049Ab3JUJdg (ORCPT ); Mon, 21 Oct 2013 05:33:36 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:39291 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753153Ab3JUIuV (ORCPT ); Mon, 21 Oct 2013 04:50:21 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "David S. Miller" , "Hannes Frederic Sowa" , "Ding Tianhong" , "YOSHIFUJI Hideaki" , "P J P" , "George Kargiotakis" Date: Mon, 21 Oct 2013 09:46:28 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 009/149] ipv6: remove max_addresses check from ipv6_create_tempaddr In-Reply-To: X-SA-Exim-Connect-IP: 212.20.242.100 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2726 Lines: 71 3.2.52-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Hannes Frederic Sowa [ Upstream commit 4b08a8f1bd8cb4541c93ec170027b4d0782dab52 ] Because of the max_addresses check attackers were able to disable privacy extensions on an interface by creating enough autoconfigured addresses: But the check is not actually needed: max_addresses protects the kernel to install too many ipv6 addresses on an interface and guards addrconf_prefix_rcv to install further addresses as soon as this limit is reached. We only generate temporary addresses in direct response of a new address showing up. As soon as we filled up the maximum number of addresses of an interface, we stop installing more addresses and thus also stop generating more temp addresses. Even if the attacker tries to generate a lot of temporary addresses by announcing a prefix and removing it again (lifetime == 0) we won't install more temp addresses, because the temporary addresses do count to the maximum number of addresses, thus we would stop installing new autoconfigured addresses when the limit is reached. This patch fixes CVE-2013-0343 (but other layer-2 attacks are still possible). Thanks to Ding Tianhong to bring this topic up again. Cc: Ding Tianhong Cc: George Kargiotakis Cc: P J P Cc: YOSHIFUJI Hideaki Signed-off-by: Hannes Frederic Sowa Acked-by: Ding Tianhong Signed-off-by: David S. Miller Signed-off-by: Ben Hutchings --- net/ipv6/addrconf.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c index 314bda2..5d41293 100644 --- a/net/ipv6/addrconf.c +++ b/net/ipv6/addrconf.c @@ -913,12 +913,10 @@ retry: if (ifp->flags & IFA_F_OPTIMISTIC) addr_flags |= IFA_F_OPTIMISTIC; - ift = !max_addresses || - ipv6_count_addresses(idev) < max_addresses ? - ipv6_add_addr(idev, &addr, tmp_plen, - ipv6_addr_type(&addr)&IPV6_ADDR_SCOPE_MASK, - addr_flags) : NULL; - if (!ift || IS_ERR(ift)) { + ift = ipv6_add_addr(idev, &addr, tmp_plen, + ipv6_addr_type(&addr)&IPV6_ADDR_SCOPE_MASK, + addr_flags); + if (IS_ERR(ift)) { in6_ifa_put(ifp); in6_dev_put(idev); printk(KERN_INFO -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/