linux-kernel - [ 042/171] netfilter: Mark SYN/ACK packets as invalid from original direction

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20121122004037.584424331@linuxfoundation.org>
Date:	Wed, 21 Nov 2012 16:39:48 -0800
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	alan@...rguk.ukuu.org.uk,
	Jozsef Kadlecsik <kadlec@...ckhole.kfki.hu>,
	Pablo Neira Ayuso <pablo@...filter.org>
Subject: [ 042/171] netfilter: Mark SYN/ACK packets as invalid from original direction

3.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jozsef Kadlecsik <kadlec@...ckhole.kfki.hu>

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@...ckhole.kfki.hu>
Signed-off-by: Pablo Neira Ayuso <pablo@...filter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 net/netfilter/nf_conntrack_proto_tcp.c |   19 ++++++++-----------
 1 file changed, 8 insertions(+), 11 deletions(-)

--- 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
  *	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 },


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/