Re: [PATCH net-next] Add uid and cookie bpf helper to cg_skb_func_proto

[Daniel Borkmann]

On 04/15/2017 02:07 AM, Alexei Starovoitov wrote:

On Fri, Apr 14, 2017 at 04:12:14PM -0700, Chenbo Feng wrote:

From: Chenbo Feng <fe...@google.com>

BPF helper functions get_socket_cookie and get_socket_uid can be
used for network traffic classifications, among others. Expose
them also to programs of type BPF_PROG_TYPE_CGROUP_SKB. As of
commit 8f917bba0042 ("bpf: pass sk to helper functions") the required
skb->sk function is available at both cgroup bpf ingress and egress
hooks.

Signed-off-by: Chenbo Feng <fe...@google.com>

Thanks for follow up.
Another alternative is to do
cg_skb_func_proto(enum bpf_func_id func_id)
{
     return sk_filter_func_proto(func_id);
}

I think all socket filter helpers are applicable to cg_skb too.

Yeah, both will effectively be the same at that point:

static const struct bpf_func_proto *
sk_filter_func_proto(enum bpf_func_id func_id)
{
        switch (func_id) {
        case BPF_FUNC_skb_load_bytes:
                return &bpf_skb_load_bytes_proto;
        case BPF_FUNC_get_socket_cookie:
                return &bpf_get_socket_cookie_proto;
        case BPF_FUNC_get_socket_uid:
                return &bpf_get_socket_uid_proto;
        default:
                return bpf_base_func_proto(func_id);
        }
}

And with the two additions:

static const struct bpf_func_proto *
cg_skb_func_proto(enum bpf_func_id func_id)
{
        switch (func_id) {
        case BPF_FUNC_skb_load_bytes:
                return &bpf_skb_load_bytes_proto;
+       case BPF_FUNC_get_socket_cookie:
+               return &bpf_get_socket_cookie_proto;
+       case BPF_FUNC_get_socket_uid:
+               return &bpf_get_socket_uid_proto;
        default:
                return bpf_base_func_proto(func_id);
        }
}