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?
+ 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 ||
[...]
