netfilter: nft_payload: simplify vlan header handling

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If the offset is within the ethernet + vlan header size boundary, then
rebuild the ethernet + vlan header and use it to copy the bytes to the
register. Otherwise, subtract the vlan header size from the offset and
fall back to use skb_copy_bits().

There is one corner case though: If the offset plus the length of the
payload instruction goes over the ethernet + vlan header boundary, then,
fetch as many bytes as possible from the rebuilt ethernet + vlan header
and fall back to copy the remaining bytes through skb_copy_bits().

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Acked-by: Florian Westphal <fw@strlen.de>

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This commit is contained in:

Pablo Neira Ayuso 2019-10-31 15:51:21 +01:00

parent 25da5eb32c

commit f41f72d09e

1 changed files with 9 additions and 19 deletions

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net/netfilter/nft_payload.c

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