xfrm: fix "disable_policy" on ipv4 early demux

[ Upstream commit 3a5913183aa1b14148c723bda030e6102ad73008 ]

The commit in the "Fixes" tag tried to avoid a case where policy check
is ignored due to dst caching in next hops.

However, when the traffic is locally consumed, the dst may be cached
in a local TCP or UDP socket as part of early demux. In this case the
"disable_policy" flag is not checked as ip_route_input_noref() was only
called before caching, and thus, packets after the initial packet in a
flow will be dropped if not matching policies.

Fix by checking the "disable_policy" flag also when a valid dst is
already available.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=216557
Reported-by: Monil Patel <monil191989@gmail.com>
Fixes: e6175a2ed1f1 ("xfrm: fix "disable_policy" flag use when arriving from different devices")
Signed-off-by: Eyal Birger <eyal.birger@gmail.com>
----

v2: use dev instead of skb->dev
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/net/ipv4/ip_input.c b/net/ipv4/ip_input.c
index 459d7e6..124bf8f 100644 (file)
--- a/net/ipv4/ip_input.c
+++ b/net/ipv4/ip_input.c
@@ -364,6 +364,11 @@ static int ip_rcv_finish_core(struct net *net, struct sock *sk,
                                           iph->tos, dev);
                if (unlikely(err))
                        goto drop_error;
+       } else {
+               struct in_device *in_dev = __in_dev_get_rcu(dev);
+
+               if (in_dev && IN_DEV_ORCONF(in_dev, NOPOLICY))
+                       IPCB(skb)->flags |= IPSKB_NOPOLICY;
        }
 
 #ifdef CONFIG_IP_ROUTE_CLASSID