bpf: add bpf_skb_change_type helper

This work adds a helper for changing skb->pkt_type in a controlled way.
We only allow a subset of possible values and can extend that in future
should other use cases come up. Doing this as a helper has the advantage
that errors can be handeled gracefully and thus helper kept extensible.

It's a write counterpart to pkt_type member we can already read from
struct __sk_buff context. Major use case is to change incoming skbs to
PACKET_HOST in a programmatic way instead of having to recirculate via
redirect(..., BPF_F_INGRESS), for example.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Daniel Borkmann
2016-06-28 12:18:28 +02:00
committed by David S. Miller
parent 6578171a7f
commit d2485c4242
2 changed files with 33 additions and 0 deletions

View File

@@ -327,6 +327,15 @@ enum bpf_func_id {
*/
BPF_FUNC_skb_change_proto,
/**
* bpf_skb_change_type(skb, type)
* Change packet type of skb.
* @skb: pointer to skb
* @type: new skb->pkt_type type
* Return: 0 on success or negative error
*/
BPF_FUNC_skb_change_type,
__BPF_FUNC_MAX_ID,
};