Re: [PATCH v3 net] bpf: add bpf_sk_netns_id() helper

[Daniel Borkmann]

On 02/04/2017 04:34 AM, Alexei Starovoitov wrote:
[...]

+BPF_CALL_1(bpf_skb_netns_id, struct sk_buff *, skb)
+{
+       struct net_device *dev = skb->dev;
+
+       if (!dev)
+               return 0;
+       return proc_get_ns_devid_inum(&dev_net(dev)->ns);
+}
+
+static const struct bpf_func_proto bpf_skb_netns_id_proto = {
+       .func           = bpf_skb_netns_id,
+       .gpl_only       = false,
+       .ret_type       = RET_INTEGER,
+       .arg1_type      = ARG_PTR_TO_CTX,
+};
+
  static const struct bpf_func_proto *
  sk_filter_func_proto(enum bpf_func_id func_id)
  {
@@ -2620,6 +2649,8 @@ sk_filter_func_proto(enum bpf_func_id func_id)
        case BPF_FUNC_trace_printk:
                if (capable(CAP_SYS_ADMIN))
                        return bpf_get_trace_printk_proto();
+       case BPF_FUNC_sk_netns_id:
+               return &bpf_skb_netns_id_proto;
        default:
                return NULL;
        }

Btw, I think here's an oversight that would still need to be
fixed. Above would mean that trace printk from unprivileged would
fall through and use &bpf_skb_netns_id_proto as proto now instead
of NULL. So BPF_FUNC_sk_netns_id needs to be placed above the
BPF_FUNC_trace_printk case, not in its fall-through path. Looks
like Chenbo in his get_socket_cookie missed this, too. Other than
that BPF bits seem good to me.

@@ -2700,6 +2731,17 @@ xdp_func_proto(enum bpf_func_id func_id)
  }