net: Fix GRE RX to use skb_transport_header for GRE header offset (1e701f16) · Commits · 戴 / test

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 <therbert@google.com> Acked-by:

Eric Dumazet <edumazet@google.com> Signed-off-by:

David S. Miller <davem@davemloft.net>

net/ipv4/gre_demux.c

+2 −3

Original line number	Diff line number	Diff line
		@@ -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);

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