[3.8.y.z extended stable] Patch "sctp: reset flowi4_oif parameter on route lookup" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    sctp: reset flowi4_oif parameter on route lookup

to the linux-3.8.y-queue branch of the 3.8.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-3.8.y-queue

This patch is scheduled to be released in version 3.8.13.24.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.8.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From d0920e17aabf7529b9aa24008f978d303679b70a Mon Sep 17 00:00:00 2001
From: Xufeng Zhang <xufeng.zhang at windriver.com>
Date: Fri, 25 Apr 2014 16:55:41 +0800
Subject: sctp: reset flowi4_oif parameter on route lookup

[ Upstream commit 85350871317a5adb35519d9dc6fc9e80809d42ad ]

commit 813b3b5db83 (ipv4: Use caller's on-stack flowi as-is
in output route lookups.) introduces another regression which
is very similar to the problem of commit e6b45241c (ipv4: reset
flowi parameters on route connect) wants to fix:
Before we call ip_route_output_key() in sctp_v4_get_dst() to
get a dst that matches a bind address as the source address,
we have already called this function previously and the flowi
parameters have been initialized including flowi4_oif, so when
we call this function again, the process in __ip_route_output_key()
will be different because of the setting of flowi4_oif, and we'll
get a networking device which corresponds to the inputted flowi4_oif
as the output device, this is wrong because we'll never hit this
place if the previously returned source address of dst match one
of the bound addresses.

To reproduce this problem, a vlan setting is enough:
  # ifconfig eth0 up
  # route del default
  # vconfig add eth0 2
  # vconfig add eth0 3
  # ifconfig eth0.2 10.0.1.14 netmask 255.255.255.0
  # route add default gw 10.0.1.254 dev eth0.2
  # ifconfig eth0.3 10.0.0.14 netmask 255.255.255.0
  # ip rule add from 10.0.0.14 table 4
  # ip route add table 4 default via 10.0.0.254 src 10.0.0.14 dev eth0.3
  # sctp_darn -H 10.0.0.14 -P 36422 -h 10.1.4.134 -p 36422 -s -I
You'll detect that all the flow are routed to eth0.2(10.0.1.254).

Signed-off-by: Xufeng Zhang <xufeng.zhang at windriver.com>
Signed-off-by: Julian Anastasov <ja at ssi.bg>
Acked-by: Vlad Yasevich <vyasevich at gmail.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 net/sctp/protocol.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/net/sctp/protocol.c b/net/sctp/protocol.c
index f898b1c..41393a2 100644
--- a/net/sctp/protocol.c
+++ b/net/sctp/protocol.c
@@ -498,8 +498,13 @@ static void sctp_v4_get_dst(struct sctp_transport *t, union sctp_addr *saddr,
 			continue;
 		if ((laddr->state == SCTP_ADDR_SRC) &&
 		    (AF_INET == laddr->a.sa.sa_family)) {
-			fl4->saddr = laddr->a.v4.sin_addr.s_addr;
 			fl4->fl4_sport = laddr->a.v4.sin_port;
+			flowi4_update_output(fl4,
+					     asoc->base.sk->sk_bound_dev_if,
+					     RT_CONN_FLAGS(asoc->base.sk),
+					     daddr->v4.sin_addr.s_addr,
+					     laddr->a.v4.sin_addr.s_addr);
+
 			rt = ip_route_output_key(sock_net(sk), fl4);
 			if (!IS_ERR(rt)) {
 				dst = &rt->dst;
--
1.9.1