netfilter: nft_payload: fix wrong mac header matching
commit d351c1ea2de3e36e608fc355d8ae7d0cc80e6cd6 upstream.
mcast packets get looped back to the local machine.
Such packets have a 0-length mac header, we should treat
this like "mac header not set" and abort rule evaluation.
As-is, we just copy data from the network header instead.
Fixes: 96518518cc
("netfilter: add nftables")
Reported-by: Blažej Krajňák <krajnak@levonet.sk>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:

committed by
Greg Kroah-Hartman

parent
fe37e56ed4
commit
287401f92c
@@ -93,7 +93,7 @@ void nft_payload_eval(const struct nft_expr *expr,
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switch (priv->base) {
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switch (priv->base) {
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case NFT_PAYLOAD_LL_HEADER:
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case NFT_PAYLOAD_LL_HEADER:
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if (!skb_mac_header_was_set(skb))
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if (!skb_mac_header_was_set(skb) || skb_mac_header_len(skb) == 0)
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goto err;
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goto err;
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if (skb_vlan_tag_present(skb)) {
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if (skb_vlan_tag_present(skb)) {
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