This is a note to let you know that I've just added the patch titled
ipv6: remove max_addresses check from ipv6_create_tempaddr
to the 3.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ipv6-remove-max_addresses-check-from-ipv6_create_tempaddr.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 79ada7773990ac5e464479790e8b4dc8ab0d48ac Mon Sep 17 00:00:00 2001
From: Hannes Frederic Sowa <hannes@xxxxxxxxxxxxxxxxxxx>
Date: Fri, 16 Aug 2013 13:02:27 +0200
Subject: ipv6: remove max_addresses check from ipv6_create_tempaddr
From: Hannes Frederic Sowa <hannes@xxxxxxxxxxxxxxxxxxx>
[ Upstream commit 4b08a8f1bd8cb4541c93ec170027b4d0782dab52 ]
Because of the max_addresses check attackers were able to disable privacy
extensions on an interface by creating enough autoconfigured addresses:
<http://seclists.org/oss-sec/2012/q4/292>
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.
Signed-off-by: Hannes Frederic Sowa <hannes@xxxxxxxxxxxxxxxxxxx>
Cc: Ding Tianhong <dingtianhong@xxxxxxxxxx>
Cc: George Kargiotakis <kargig@xxxxxxx>
Cc: P J P <ppandit@xxxxxxxxxx>
Cc: YOSHIFUJI Hideaki <yoshfuji@xxxxxxxxxxxxxx>
Acked-by: Ding Tianhong <dingtianhong@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/ipv6/addrconf.c | 10 ++++------
1 file changed, 4 insertions(+), 6 deletions(-)
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -910,12 +910,10 @@ 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
Patches currently in stable-queue which might be from hannes@xxxxxxxxxxxxxxxxxxx are
queue-3.4/net-bridge-convert-mldv2-query-mrc-into-msecs_to_jiffies-for-max_delay.patch
queue-3.4/ipv6-don-t-stop-backtracking-in-fib6_lookup_1-if-subtree-does-not-match.patch
queue-3.4/ipv6-don-t-depend-on-per-socket-memory-for-neighbour-discovery-messages.patch
queue-3.4/ipv6-remove-max_addresses-check-from-ipv6_create_tempaddr.patch
queue-3.4/icmpv6-treat-dest-unreachable-codes-5-and-6-as-eacces-not-eproto.patch
queue-3.4/ipv6-drop-packets-with-multiple-fragmentation-headers.patch
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