On Sat, Dec 03, 2016 at 01:22:05AM +0100, Daniel Borkmann wrote:
> On 12/03/2016 12:23 AM, Martin KaFai Lau wrote:
> >This patch allows XDP prog to extend/remove the packet
> >data at the head (like adding or removing header). It is
> >done by adding a new XDP helper bpf_xdp_adjust_head().
> >
> >It also renames bpf_helper_changes_skb_data() to
> >bpf_helper_changes_pkt_data() to better reflect
> >that XDP prog does not work on skb.
> >
> >Signed-off-by: Martin KaFai Lau <ka...@fb.com>
> [...]
> >diff --git a/net/core/filter.c b/net/core/filter.c
> >index 56b43587d200..6902e2f73e38 100644
> >--- a/net/core/filter.c
> >+++ b/net/core/filter.c
> >@@ -2234,7 +2234,34 @@ static const struct bpf_func_proto
> >bpf_skb_change_head_proto = {
> > .arg3_type = ARG_ANYTHING,
> > };
> >
> >-bool bpf_helper_changes_skb_data(void *func)
> >+BPF_CALL_2(bpf_xdp_adjust_head, struct xdp_buff *, xdp, int, offset)
> >+{
> >+ /* Both mlx4 and mlx5 driver align each packet to PAGE_SIZE when
> >+ * XDP prog is set.
> >+ * If the above is not true for the other drivers to support
> >+ * bpf_xdp_adjust_head, struct xdp_buff can be extended.
> >+ */
> >+ void *head = (void *)((unsigned long)xdp->data & PAGE_MASK);
> >+ void *new_data = xdp->data + offset;
> >+
> >+ if (new_data < head || new_data >= xdp->data_end)
> >+ /* The packet length must be >=1 */
>
> Patch looks generally good to me. Should the min pkt len here be
> limited to ETH_HLEN instead of 1?
Make sense. Will make the change.
>
> >+ return -EINVAL;
> >+
> >+ xdp->data = new_data;
> >+
> >+ return 0;
> >+}
> >+
> >+static const struct bpf_func_proto bpf_xdp_adjust_head_proto = {
> >+ .func = bpf_xdp_adjust_head,
> >+ .gpl_only = false,
> >+ .ret_type = RET_INTEGER,
> >+ .arg1_type = ARG_PTR_TO_CTX,
> >+ .arg2_type = ARG_ANYTHING,
> >+};
> >+
> >+bool bpf_helper_changes_pkt_data(void *func)
> > {
> > if (func == bpf_skb_vlan_push ||
> > func == bpf_skb_vlan_pop ||
> [...]
