linux-kernel - [PATCH 4.4 48/86] gre: do not keep the GRE header around in collect medata mode

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Date:   Mon, 18 May 2020 19:36:19 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Jiri Benc <jbenc@...hat.com>,
        "David S. Miller" <davem@...emloft.net>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.4 48/86] gre: do not keep the GRE header around in collect medata mode

From: Jiri Benc <jbenc@...hat.com>

[ Upstream commit e271c7b4420ddbb9fae82a2b31a5ab3edafcf4fe ]

For ipgre interface in collect metadata mode, it doesn't make sense for the
interface to be of ARPHRD_IPGRE type. The outer header of received packets
is not needed, as all the information from it is present in metadata_dst. We
already don't set ipgre_header_ops for collect metadata interfaces, which is
the only consumer of mac_header pointing to the outer IP header.

Just set the interface type to ARPHRD_NONE in collect metadata mode for
ipgre (not gretap, that still correctly stays ARPHRD_ETHER) and reset
mac_header.

Fixes: a64b04d86d14 ("gre: do not assign header_ops in collect metadata mode")
Fixes: 2e15ea390e6f4 ("ip_gre: Add support to collect tunnel metadata.")
Signed-off-by: Jiri Benc <jbenc@...hat.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 net/ipv4/ip_gre.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index e5448570d6483..900ee28bda99a 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -399,7 +399,10 @@ static int ipgre_rcv(struct sk_buff *skb, const struct tnl_ptk_info *tpi)
 				  iph->saddr, iph->daddr, tpi->key);
 
 	if (tunnel) {
-		skb_pop_mac_header(skb);
+		if (tunnel->dev->type != ARPHRD_NONE)
+			skb_pop_mac_header(skb);
+		else
+			skb_reset_mac_header(skb);
 		if (tunnel->collect_md) {
 			__be16 flags;
 			__be64 tun_id;
@@ -1015,6 +1018,8 @@ static void ipgre_netlink_parms(struct net_device *dev,
 		struct ip_tunnel *t = netdev_priv(dev);
 
 		t->collect_md = true;
+		if (dev->type == ARPHRD_IPGRE)
+			dev->type = ARPHRD_NONE;
 	}
 }
 
-- 
2.20.1