netfilter: nft_inner: set tunnel offset to GRE header offset

Set inner tunnel offset to the GRE header, this is redundant to existing
transport header offset, but this normalizes the handling of the tunnel
header regardless its location in the layering. GRE version 0 is overloaded
with RFCs, the type decorator in the inner expression might also be useful
to interpret matching fields from the netlink delinearize path in userspace.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/net/netfilter/nft_inner.c b/net/netfilter/nft_inner.c
index 19fdc8c70cd1bf774d2adec835c46e9754e32cd1..eae7caeff316a7e90e5f1038812990c7f41fa8a9 100644 (file)
--- a/net/netfilter/nft_inner.c
+++ b/net/netfilter/nft_inner.c
@@ -174,8 +174,13 @@ static int nft_inner_parse_tunhdr(const struct nft_inner *priv,
                                  const struct nft_pktinfo *pkt,
                                  struct nft_inner_tun_ctx *ctx, u32 *off)
 {
-       if (pkt->tprot != IPPROTO_UDP ||
-           pkt->tprot != IPPROTO_GRE)
+       if (pkt->tprot == IPPROTO_GRE) {
+               ctx->inner_tunoff = pkt->thoff;
+               ctx->flags |= NFT_PAYLOAD_CTX_INNER_TUN;
+               return 0;
+       }
+
+       if (pkt->tprot != IPPROTO_UDP)
                return -1;
 
        ctx->inner_tunoff = *off;