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Pablo Neira Ayuso
d27e2798e3
[ Upstream commit0ae8e4cca7] Before this patch, transport offset (pkt->thoff) provides an offset relative to the network header. This is fine for the inet families because skb->data points to the network header in such case. However, from netdev/egress, skb->data points to the mac header (if available), thus, pkt->thoff is missing the mac header length. Add skb_network_offset() to the transport offset (pkt->thoff) for netdev, so transport header mangling works as expected. Adjust payload fast eval function to use skb->data now that pkt->thoff provides an absolute offset. This explains why users report that matching on egress/netdev works but payload mangling does not. This patch implicitly fixes payload mangling for IPv4 packets in netdev/egress given skb_store_bits() requires an offset from skb->data to reach the transport header. I suspect that nft_exthdr and the trace infra were also broken from netdev/egress because they also take skb->data as start, and pkt->thoff was not correct. Note that IPv6 is fine because ipv6_find_hdr() already provides a transport offset starting from skb->data, which includes skb_network_offset(). The bridge family also uses nft_set_pktinfo_ipv4_validate(), but there skb_network_offset() is zero, so the update in this patch does not alter the existing behaviour. Fixes:42df6e1d22("netfilter: Introduce egress hook") Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
Linux kernel
============
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