net: ip_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 tunnel lookup fail in ip6gre_err.
In addition remove key field parsing and pskb_may_pull check in
erspan_rcv and ip6erspan_rcv

Fixes: 5a963eb61b7c ("ip6_gre: Add ERSPAN native tunnel support")
Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 17 insertions, 13 deletions

diff --git a/net/ipv4/gre_demux.c b/net/ipv4/gre_demux.c
index a4bf22ee3aed..7c4a41dc04bb 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 +120,22 @@ 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 (greh->protocol == htons(ETH_P_ERSPAN) ||
+            greh->protocol == htons(ETH_P_ERSPAN2)) {
+                struct erspan_base_hdr *ershdr;
+
+                if (!pskb_may_pull(skb, nhs + hdr_len + sizeof(*ershdr)))
+                        return -EINVAL;
+
+                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 b1a74d80d868..20a64fe6254b 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -268,20 +268,11 @@ static int erspan_rcv(struct sk_buff *skb, struct tnl_ptk_info *tpi,
         int len;
 
         itn = net_generic(net, erspan_net_id);
-        len = gre_hdr_len + sizeof(*ershdr);
-
-        /* Check based hdr len */
-        if (unlikely(!pskb_may_pull(skb, len)))
-                return PACKET_REJECT;
 
         iph = ip_hdr(skb);
         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 b1be67ca6768..4416368dbd49 100644
--- a/net/ipv6/ip6_gre.c
+++ b/net/ipv6/ip6_gre.c
@@ -534,13 +534,9 @@ static int ip6erspan_rcv(struct sk_buff *skb, int gre_hdr_len,
         struct ip6_tnl *tunnel;
         u8 ver;
 
-        if (unlikely(!pskb_may_pull(skb, sizeof(*ershdr))))
-                return PACKET_REJECT;
-
         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,