net: bridge: add BRIDGE_VLAN_INFO_DYNAMIC flag

Allow a userspace VLAN registration protocol (e.g. an MVRP daemon) to
mark the bridge VLAN entries it creates as dynamic, so they can be
distinguished from administratively configured (static) entries, which
the kernel VLAN table otherwise cannot express. The flag is stored on
add, cleared when the entry is re-added without it, and reported in
getlink and VLAN DB dumps and notifications. Analogous to the FDB's
NTF_EXT_LEARNED.

Signed-off-by: Luke Howard <lukeh@padl.com>

Author: lhoward

include/uapi/linux/if_bridge.h

@@ -134,6 +134,7 @@ enum {
 #define BRIDGE_VLAN_INFO_RANGE_END	(1<<4) /* VLAN is end of vlan range */
 #define BRIDGE_VLAN_INFO_BRENTRY	(1<<5) /* Global bridge VLAN entry */
 #define BRIDGE_VLAN_INFO_ONLY_OPTS	(1<<6) /* Skip create/delete/flags */
+#define BRIDGE_VLAN_INFO_DYNAMIC	(1<<7) /* 802.1Q Dynamic VLAN Registration Entry */
 
 struct bridge_vlan_info {
 	__u16 flags;

net/bridge/br_netlink.c

@@ -382,6 +382,9 @@ static int br_fill_ifvlaninfo_compressed(struct sk_buff *skb,
 		if (v->flags & BRIDGE_VLAN_INFO_UNTAGGED)
 			flags |= BRIDGE_VLAN_INFO_UNTAGGED;
 
+		if (v->flags & BRIDGE_VLAN_INFO_DYNAMIC)
+			flags |= BRIDGE_VLAN_INFO_DYNAMIC;
+
 		if (vid_range_start == 0) {
 			goto initvars;
 		} else if ((v->vid - vid_range_end) == 1 &&
@@ -434,6 +437,9 @@ static int br_fill_ifvlaninfo(struct sk_buff *skb,
 		if (v->flags & BRIDGE_VLAN_INFO_UNTAGGED)
 			vinfo.flags |= BRIDGE_VLAN_INFO_UNTAGGED;
 
+		if (v->flags & BRIDGE_VLAN_INFO_DYNAMIC)
+			vinfo.flags |= BRIDGE_VLAN_INFO_DYNAMIC;
+
 		if (nla_put(skb, IFLA_BRIDGE_VLAN_INFO,
 			    sizeof(vinfo), &vinfo))
 			goto nla_put_failure;

net/bridge/br_vlan.c

@@ -54,9 +54,11 @@ static void __vlan_delete_pvid(struct net_bridge_vlan_group *vg, u16 vid)
 	vg->pvid = 0;
 }
 
-/* Update the BRIDGE_VLAN_INFO_PVID and BRIDGE_VLAN_INFO_UNTAGGED flags of @v.
- * If @commit is false, return just whether the BRIDGE_VLAN_INFO_PVID and
- * BRIDGE_VLAN_INFO_UNTAGGED bits of @flags would produce any change onto @v.
+/* Update the BRIDGE_VLAN_INFO_PVID, BRIDGE_VLAN_INFO_UNTAGGED and
+ * BRIDGE_VLAN_INFO_DYNAMIC flags of @v.
+ * If @commit is false, return just whether the BRIDGE_VLAN_INFO_PVID,
+ * BRIDGE_VLAN_INFO_UNTAGGED and BRIDGE_VLAN_INFO_DYNAMIC bits of @flags
+ * would produce any change onto @v.
  */
 static bool __vlan_flags_update(struct net_bridge_vlan *v, u16 flags,
 				bool commit)
@@ -71,7 +73,8 @@ static bool __vlan_flags_update(struct net_bridge_vlan *v, u16 flags,
 
 	/* check if anything would be changed on commit */
 	change = !!(flags & BRIDGE_VLAN_INFO_PVID) == !!(vg->pvid != v->vid) ||
-		 ((flags ^ v->flags) & BRIDGE_VLAN_INFO_UNTAGGED);
+		 ((flags ^ v->flags) & (BRIDGE_VLAN_INFO_UNTAGGED |
+					BRIDGE_VLAN_INFO_DYNAMIC));
 
 	if (!commit)
 		goto out;
@@ -86,6 +89,11 @@ static bool __vlan_flags_update(struct net_bridge_vlan *v, u16 flags,
 	else
 		v->flags &= ~BRIDGE_VLAN_INFO_UNTAGGED;
 
+	if (flags & BRIDGE_VLAN_INFO_DYNAMIC)
+		v->flags |= BRIDGE_VLAN_INFO_DYNAMIC;
+	else
+		v->flags &= ~BRIDGE_VLAN_INFO_DYNAMIC;
+
 out:
 	return change;
 }
@@ -1869,6 +1877,8 @@ static bool br_vlan_fill_vids(struct sk_buff *skb, u16 vid, u16 vid_range,
 		info.flags |= BRIDGE_VLAN_INFO_UNTAGGED;
 	if (flags & BRIDGE_VLAN_INFO_PVID)
 		info.flags |= BRIDGE_VLAN_INFO_PVID;
+	if (flags & BRIDGE_VLAN_INFO_DYNAMIC)
+		info.flags |= BRIDGE_VLAN_INFO_DYNAMIC;
 
 	if (nla_put(skb, BRIDGE_VLANDB_ENTRY_INFO, sizeof(info), &info))
 		goto out_err;