netdev - [PATCH net] net: ip6_gre: use erspan key field for tunnel lookup

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Message-Id: <044b51ecc8d0bc21faf8755e2f3014e8b65d71ec.1547569872.git.lorenzo.bianconi@redhat.com>
Date:   Tue, 15 Jan 2019 17:43:15 +0100
From:   Lorenzo Bianconi <lorenzo.bianconi@...hat.com>
To:     davem@...emloft.net
Cc:     netdev@...r.kernel.org, u9012063@...il.com
Subject: [PATCH net] net: ip6_gre: use erspan key field for tunnel lookup

Use ERSPAN key header field as tunnel key in gre_parse_header routine
since ERSPAN protocol sets the key field of the external GRE header to
0 resulting in a possible tunnel lookup fail.
In addition remove key field parsing in erspan_rcv and ip6erspan_rcv

Fixes: 5a963eb61b7c ("ip6_gre: Add ERSPAN native tunnel support")
Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@...hat.com>
---
 net/ipv4/gre_demux.c | 14 ++++++++++++++
 net/ipv4/ip_gre.c    |  4 ----
 net/ipv6/ip6_gre.c   |  1 -
 3 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/net/ipv4/gre_demux.c b/net/ipv4/gre_demux.c
index a4bf22ee3aed..ee09d657606e 100644
--- a/net/ipv4/gre_demux.c
+++ b/net/ipv4/gre_demux.c
@@ -25,6 +25,7 @@
 #include <linux/spinlock.h>
 #include <net/protocol.h>
 #include <net/gre.h>
+#include <net/erspan.h>
 
 #include <net/icmp.h>
 #include <net/route.h>
@@ -119,6 +120,19 @@ int gre_parse_header(struct sk_buff *skb, struct tnl_ptk_info *tpi,
 			hdr_len += 4;
 	}
 	tpi->hdr_len = hdr_len;
+
+	/* ERSPAN ver 1 and 2 protocol sets GRE key field
+	 * to 0 and sets the configured key in the
+	 * inner erspan header field
+	 */
+	if (tpi->proto == htons(ETH_P_ERSPAN) ||
+	    tpi->proto == htons(ETH_P_ERSPAN2)) {
+		struct erspan_base_hdr *ershdr;
+
+		ershdr = (struct erspan_base_hdr *)options;
+		tpi->key = cpu_to_be32(get_session_id(ershdr));
+	}
+
 	return hdr_len;
 }
 EXPORT_SYMBOL(gre_parse_header);
diff --git a/net/ipv4/ip_gre.c b/net/ipv4/ip_gre.c
index d1d09f3e5f9e..c9238ca67413 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -278,10 +278,6 @@ static int erspan_rcv(struct sk_buff *skb, struct tnl_ptk_info *tpi,
 	ershdr = (struct erspan_base_hdr *)(skb->data + gre_hdr_len);
 	ver = ershdr->ver;
 
-	/* The original GRE header does not have key field,
-	 * Use ERSPAN 10-bit session ID as key.
-	 */
-	tpi->key = cpu_to_be32(get_session_id(ershdr));
 	tunnel = ip_tunnel_lookup(itn, skb->dev->ifindex,
 				  tpi->flags | TUNNEL_KEY,
 				  iph->saddr, iph->daddr, tpi->key);
diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c
index 09d0826742f8..961a96355ddb 100644
--- a/net/ipv6/ip6_gre.c
+++ b/net/ipv6/ip6_gre.c
@@ -540,7 +540,6 @@ static int ip6erspan_rcv(struct sk_buff *skb, int gre_hdr_len,
 	ipv6h = ipv6_hdr(skb);
 	ershdr = (struct erspan_base_hdr *)skb->data;
 	ver = ershdr->ver;
-	tpi->key = cpu_to_be32(get_session_id(ershdr));
 
 	tunnel = ip6gre_tunnel_lookup(skb->dev,
 				      &ipv6h->saddr, &ipv6h->daddr, tpi->key,
-- 
2.20.1