wg: get public key as non-root

[Klemens Nanni]

Is there any particular reason why an interface's *public* key is only
shown to the root user in ifconfig?

Similar to `wgport', I'd like to see the public key as non-root user as
well for convenience:

        $ ifconfig wg0
        wg0: flags=80c3<UP,BROADCAST,RUNNING,NOARP,MULTICAST> mtu 1420
                index 5 priority 0 llprio 3
                wgport 1078
                wgpubkey mrtNB07tzEJKyJDvhaov7QYt487BXLK3hnnZB+pDIhM=
                groups: wg
                inet6 ... prefixlen 126

This makes the SIOCGWG ioctl return the public key to unprivileged users
such ifconfig read it.

Feedback? Objections? OK?

diff --git a/sys/net/if_wg.c b/sys/net/if_wg.c
index 3f59681fe..f9a145b37 100644
--- a/sys/net/if_wg.c
+++ b/sys/net/if_wg.c
@@ -2374,12 +2374,14 @@ wg_ioctl_get(struct wg_softc *sc, struct wg_data_io 
*data)
                iface_o.i_flags |= WG_INTERFACE_HAS_RTABLE;
        }
 
+       if (noise_local_keys(&sc->sc_local, iface_o.i_public, NULL) == 0) {
+               iface_o.i_flags |= WG_INTERFACE_HAS_PUBLIC;
+       }
+
        if (!is_suser)
                goto copy_out_iface;
 
-       if (noise_local_keys(&sc->sc_local, iface_o.i_public,
-           iface_o.i_private) == 0) {
-               iface_o.i_flags |= WG_INTERFACE_HAS_PUBLIC;
+       if (noise_local_keys(&sc->sc_local, NULL, iface_o.i_private) == 0) {
                iface_o.i_flags |= WG_INTERFACE_HAS_PRIVATE;
        }