net: bridge: fdb: add support for flush filtering based on ifindex and vlan

Add support for fdb flush filtering based on destination ifindex and
vlan id. The ifindex must either match a port's device ifindex or the
bridge's. The vlan support is trivial since it's already validated by
rtnl_fdb_del, we just need to fill it in.
Signed-off-by: Nikolay Aleksandrov <razor@blackwall.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/bridge/br_fdb.c

@@ -622,12 +622,44 @@ static unsigned long __ndm_flags_to_fdb_flags(u8 ndm_flags)
 	return flags;
 }
 
+static int __fdb_flush_validate_ifindex(const struct net_bridge *br,
+					int ifindex,
+					struct netlink_ext_ack *extack)
+{
+	const struct net_device *dev;
+
+	dev = __dev_get_by_index(dev_net(br->dev), ifindex);
+	if (!dev) {
+		NL_SET_ERR_MSG_MOD(extack, "Unknown flush device ifindex");
+		return -ENODEV;
+	}
+	if (!netif_is_bridge_master(dev) && !netif_is_bridge_port(dev)) {
+		NL_SET_ERR_MSG_MOD(extack, "Flush device is not a bridge or bridge port");
+		return -EINVAL;
+	}
+	if (netif_is_bridge_master(dev) && dev != br->dev) {
+		NL_SET_ERR_MSG_MOD(extack,
+				   "Flush bridge device does not match target bridge device");
+		return -EINVAL;
+	}
+	if (netif_is_bridge_port(dev)) {
+		struct net_bridge_port *p = br_port_get_rtnl(dev);
+
+		if (p->br != br) {
+			NL_SET_ERR_MSG_MOD(extack, "Port belongs to a different bridge device");
+			return -EINVAL;
+		}
+	}
+
+	return 0;
+}
+
 int br_fdb_delete_bulk(struct ndmsg *ndm, struct nlattr *tb[],
 		       struct net_device *dev, u16 vid,
 		       struct netlink_ext_ack *extack)
 {
 	u8 ndm_flags = ndm->ndm_flags & ~FDB_FLUSH_IGNORED_NDM_FLAGS;
-	struct net_bridge_fdb_flush_desc desc = {};
+	struct net_bridge_fdb_flush_desc desc = { .vlan_id = vid };
 	struct net_bridge_port *p = NULL;
 	struct net_bridge *br;
 
@@ -663,6 +695,17 @@ int br_fdb_delete_bulk(struct ndmsg *ndm, struct nlattr *tb[],
 
 		desc.flags_mask |= __ndm_flags_to_fdb_flags(ndm_flags_mask);
 	}
+	if (tb[NDA_IFINDEX]) {
+		int err, ifidx = nla_get_s32(tb[NDA_IFINDEX]);
+
+		err = __fdb_flush_validate_ifindex(br, ifidx, extack);
+		if (err)
+			return err;
+		desc.port_ifindex = ifidx;
+	} else if (p) {
+		/* flush was invoked with port device and NTF_MASTER */
+		desc.port_ifindex = p->dev->ifindex;
+	}
 
 	br_debug(br, "flushing port ifindex: %d vlan id: %u flags: 0x%lx flags mask: 0x%lx\n",
 		 desc.port_ifindex, desc.vlan_id, desc.flags, desc.flags_mask);