From 1e701f16982a9d15488a5aa8c7f5c41444b1de67 Mon Sep 17 00:00:00 2001 From: Tom Herbert Date: Mon, 8 Sep 2014 08:29:12 -0700 Subject: [PATCH] net: Fix GRE RX to use skb_transport_header for GRE header offset GRE assumes that the GRE header is at skb_network_header + ip_hrdlen(skb). It is more general to use skb_transport_header and this allows the possbility of inserting additional header between IP and GRE (which is what we will done in Generic UDP Encapsulation for GRE). Signed-off-by: Tom Herbert Acked-by: Eric Dumazet Signed-off-by: David S. Miller --- net/ipv4/gre_demux.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/net/ipv4/gre_demux.c b/net/ipv4/gre_demux.c index 7e0756da8737..4a7b5b2a1ce3 100644 --- a/net/ipv4/gre_demux.c +++ b/net/ipv4/gre_demux.c @@ -98,7 +98,6 @@ EXPORT_SYMBOL_GPL(gre_build_header); static int parse_gre_header(struct sk_buff *skb, struct tnl_ptk_info *tpi, bool *csum_err) { - unsigned int ip_hlen = ip_hdrlen(skb); const struct gre_base_hdr *greh; __be32 *options; int hdr_len; @@ -106,7 +105,7 @@ static int parse_gre_header(struct sk_buff *skb, struct tnl_ptk_info *tpi, if (unlikely(!pskb_may_pull(skb, sizeof(struct gre_base_hdr)))) return -EINVAL; - greh = (struct gre_base_hdr *)(skb_network_header(skb) + ip_hlen); + greh = (struct gre_base_hdr *)skb_transport_header(skb); if (unlikely(greh->flags & (GRE_VERSION | GRE_ROUTING))) return -EINVAL; @@ -116,7 +115,7 @@ static int parse_gre_header(struct sk_buff *skb, struct tnl_ptk_info *tpi, if (!pskb_may_pull(skb, hdr_len)) return -EINVAL; - greh = (struct gre_base_hdr *)(skb_network_header(skb) + ip_hlen); + greh = (struct gre_base_hdr *)skb_transport_header(skb); tpi->proto = greh->protocol; options = (__be32 *)(greh + 1); -- 2.20.1