netdev - [PATCH net 2/2] tcp: use IPCB instead of TCP_SKB_CB in inet_exact_dif

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Message-Id: <20171203173300.21149-3-edumazet@google.com>
Date:   Sun,  3 Dec 2017 09:33:00 -0800
From:   Eric Dumazet <edumazet@...gle.com>
To:     "David S . Miller" <davem@...emloft.net>
Cc:     netdev <netdev@...r.kernel.org>,
        Eric Dumazet <eric.dumazet@...il.com>,
        David Ahern <dsa@...ulusnetworks.com>,
        James Morris <james.l.morris@...cle.com>,
        Casey Schaufler <casey@...aufler-ca.com>,
        David Ahern <dsahern@...il.com>,
        Eric Dumazet <edumazet@...gle.com>
Subject: [PATCH net 2/2] tcp: use IPCB instead of TCP_SKB_CB in inet_exact_dif_match()

From: David Ahern <dsahern@...il.com>

After this fix : ("tcp: add tcp_v4_fill_cb()/tcp_v4_restore_cb()"),
socket lookups happen while skb->cb[] has not been mangled yet by TCP.

Fixes: a04a480d4392 ("net: Require exact match for TCP socket lookups if dif is l3mdev")
Signed-off-by: David Ahern <dsahern@...il.com>
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 include/net/tcp.h | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/include/net/tcp.h b/include/net/tcp.h
index 4e09398009c10a72478b43d3cffc24ba01612b91..6998707e81f343ef8d893c0b2ba16db541082230 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -844,12 +844,11 @@ static inline int tcp_v6_sdif(const struct sk_buff *skb)
 }
 #endif
 
-/* TCP_SKB_CB reference means this can not be used from early demux */
 static inline bool inet_exact_dif_match(struct net *net, struct sk_buff *skb)
 {
 #if IS_ENABLED(CONFIG_NET_L3_MASTER_DEV)
 	if (!net->ipv4.sysctl_tcp_l3mdev_accept &&
-	    skb && ipv4_l3mdev_skb(TCP_SKB_CB(skb)->header.h4.flags))
+	    skb && ipv4_l3mdev_skb(IPCB(skb)->flags))
 		return true;
 #endif
 	return false;
-- 
2.15.0.531.g2ccb3012c9-goog