Re: [PATCH v10 04/12] rtnl: add option for setting link xdp prog

[Daniel Borkmann]

On 07/19/2016 09:16 PM, Brenden Blanco wrote:

Sets the bpf program represented by fd as an early filter in the rx path
of the netdev. The fd must have been created as BPF_PROG_TYPE_XDP.
Providing a negative value as fd clears the program. Getting the fd back
via rtnl is not possible, therefore reading of this value merely
provides a bool whether the program is valid on the link or not.

Signed-off-by: Brenden Blanco <bbla...@plumgrid.com>

[...]

@@ -2054,6 +2101,23 @@ static int do_setlink(const struct sk_buff *skb,
                status |= DO_SETLINK_NOTIFY;
        }

+       if (tb[IFLA_XDP]) {
+               struct nlattr *xdp[IFLA_XDP_MAX + 1];
+
+               err = nla_parse_nested(xdp, IFLA_XDP_MAX, tb[IFLA_XDP],
+                                      ifla_xdp_policy);
+               if (err < 0)
+                       goto errout;
+
+               if (xdp[IFLA_XDP_FD]) {
+                       err = dev_change_xdp_fd(dev,
+                                               nla_get_s32(xdp[IFLA_XDP_FD]));
+                       if (err)
+                               goto errout;
+                       status |= DO_SETLINK_NOTIFY;
+               }

For the setlink case IFLA_XDP_ATTACHED has no meaning currently, so I'd
suggest it would be good to be strict and still add a:

                /* Only used in rtnl_fill_ifinfo currently. */
                if (xdp[IFLA_XDP_ATTACHED]) {
                        err = -EINVAL;
                        goto errout;
                }

+       }
+
  errout:
        if (status & DO_SETLINK_MODIFIED) {
                if (status & DO_SETLINK_NOTIFY)