[ 3.5.y.z extended stable ] Patch "netfilter: Mark SYN/ACK packets as invalid from original" has been added to staging queue
Herton Ronaldo Krzesinski
herton.krzesinski at canonical.com
Wed Dec 12 05:11:53 UTC 2012
This is a note to let you know that I have just added a patch titled
netfilter: Mark SYN/ACK packets as invalid from original
to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree
which can be found at:
http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue
If you, or anyone else, feels it should not be added to this tree, please
reply to this email.
For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable
Thanks.
-Herton
------
>From 9fc64173c02e3efd1e7b72eb7ec74f59e65dd9d6 Mon Sep 17 00:00:00 2001
From: Jozsef Kadlecsik <kadlec at blackhole.kfki.hu>
Date: Fri, 31 Aug 2012 09:55:53 +0000
Subject: [PATCH] netfilter: Mark SYN/ACK packets as invalid from original
direction
commit 64f509ce71b08d037998e93dd51180c19b2f464c upstream.
Clients should not send such packets. By accepting them, we open
up a hole by wich ephemeral ports can be discovered in an off-path
attack.
See: "Reflection scan: an Off-Path Attack on TCP" by Jan Wrobel,
http://arxiv.org/abs/1201.2074
Signed-off-by: Jozsef Kadlecsik <kadlec at blackhole.kfki.hu>
Signed-off-by: Pablo Neira Ayuso <pablo at netfilter.org>
Signed-off-by: Herton Ronaldo Krzesinski <herton.krzesinski at canonical.com>
---
net/netfilter/nf_conntrack_proto_tcp.c | 19 ++++++++-----------
1 file changed, 8 insertions(+), 11 deletions(-)
diff --git a/net/netfilter/nf_conntrack_proto_tcp.c b/net/netfilter/nf_conntrack_proto_tcp.c
index 21ff1a9..6638ad5 100644
--- a/net/netfilter/nf_conntrack_proto_tcp.c
+++ b/net/netfilter/nf_conntrack_proto_tcp.c
@@ -158,21 +158,18 @@ static const u8 tcp_conntracks[2][6][TCP_CONNTRACK_MAX] = {
* sCL -> sSS
*/
/* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */
-/*synack*/ { sIV, sIV, sIG, sIG, sIG, sIG, sIG, sIG, sIG, sSR },
+/*synack*/ { sIV, sIV, sSR, sIV, sIV, sIV, sIV, sIV, sIV, sSR },
/*
* sNO -> sIV Too late and no reason to do anything
* sSS -> sIV Client can't send SYN and then SYN/ACK
* sS2 -> sSR SYN/ACK sent to SYN2 in simultaneous open
- * sSR -> sIG
- * sES -> sIG Error: SYNs in window outside the SYN_SENT state
- * are errors. Receiver will reply with RST
- * and close the connection.
- * Or we are not in sync and hold a dead connection.
- * sFW -> sIG
- * sCW -> sIG
- * sLA -> sIG
- * sTW -> sIG
- * sCL -> sIG
+ * sSR -> sSR Late retransmitted SYN/ACK in simultaneous open
+ * sES -> sIV Invalid SYN/ACK packets sent by the client
+ * sFW -> sIV
+ * sCW -> sIV
+ * sLA -> sIV
+ * sTW -> sIV
+ * sCL -> sIV
*/
/* sNO, sSS, sSR, sES, sFW, sCW, sLA, sTW, sCL, sS2 */
/*fin*/ { sIV, sIV, sFW, sFW, sLA, sLA, sLA, sTW, sCL, sIV },
--
1.7.9.5
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