net: bridge: add support for sticky fdb entries

Add support for entries which are "sticky", i.e. will not change their port
if they show up from a different one. A new ndm flag is introduced for that
purpose - NTF_STICKY. We allow to set it only to non-local entries.

Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/uapi/linux/neighbour.h b/include/uapi/linux/neighbour.h
index 904db61..9981554 100644 (file)
--- a/include/uapi/linux/neighbour.h
+++ b/include/uapi/linux/neighbour.h
@@ -43,6 +43,7 @@ enum {
 #define NTF_PROXY      0x08    /* == ATF_PUBL */
 #define NTF_EXT_LEARNED        0x10
 #define NTF_OFFLOADED   0x20
+#define NTF_STICKY     0x40
 #define NTF_ROUTER     0x80
 
 /*

diff --git a/net/bridge/br_fdb.c b/net/bridge/br_fdb.c
index 502f663..a56ed7f 100644 (file)
--- a/net/bridge/br_fdb.c
+++ b/net/bridge/br_fdb.c
@@ -584,7 +584,7 @@ void br_fdb_update(struct net_bridge *br, struct net_bridge_port *source,
                        unsigned long now = jiffies;
 
                        /* fastpath: update of existing entry */
-                       if (unlikely(source != fdb->dst)) {
+                       if (unlikely(source != fdb->dst && !fdb->is_sticky)) {
                                fdb->dst = source;
                                fdb_modified = true;
                                /* Take over HW learned entry */
@@ -656,6 +656,8 @@ static int fdb_fill_info(struct sk_buff *skb, const struct net_bridge *br,
                ndm->ndm_flags |= NTF_OFFLOADED;
        if (fdb->added_by_external_learn)
                ndm->ndm_flags |= NTF_EXT_LEARNED;
+       if (fdb->is_sticky)
+               ndm->ndm_flags |= NTF_STICKY;
 
        if (nla_put(skb, NDA_LLADDR, ETH_ALEN, &fdb->key.addr))
                goto nla_put_failure;
@@ -772,8 +774,10 @@ skip:
 
 /* Update (create or replace) forwarding database entry */
 static int fdb_add_entry(struct net_bridge *br, struct net_bridge_port *source,
-                        const __u8 *addr, __u16 state, __u16 flags, __u16 vid)
+                        const u8 *addr, u16 state, u16 flags, u16 vid,
+                        u8 ndm_flags)
 {
+       u8 is_sticky = !!(ndm_flags & NTF_STICKY);
        struct net_bridge_fdb_entry *fdb;
        bool modified = false;
 
@@ -789,6 +793,9 @@ static int fdb_add_entry(struct net_bridge *br, struct net_bridge_port *source,
                return -EINVAL;
        }
 
+       if (is_sticky && (state & NUD_PERMANENT))
+               return -EINVAL;
+
        fdb = br_fdb_find(br, addr, vid);
        if (fdb == NULL) {
                if (!(flags & NLM_F_CREATE))
@@ -832,6 +839,12 @@ static int fdb_add_entry(struct net_bridge *br, struct net_bridge_port *source,
 
                modified = true;
        }
+
+       if (is_sticky != fdb->is_sticky) {
+               fdb->is_sticky = is_sticky;
+               modified = true;
+       }
+
        fdb->added_by_user = 1;
 
        fdb->used = jiffies;
@@ -865,7 +878,7 @@ static int __br_fdb_add(struct ndmsg *ndm, struct net_bridge *br,
        } else {
                spin_lock_bh(&br->hash_lock);
                err = fdb_add_entry(br, p, addr, ndm->ndm_state,
-                                   nlh_flags, vid);
+                                   nlh_flags, vid, ndm->ndm_flags);
                spin_unlock_bh(&br->hash_lock);
        }
 

diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index 11ed202..d21035a 100644 (file)
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -181,6 +181,7 @@ struct net_bridge_fdb_entry {
        struct hlist_node               fdb_node;
        unsigned char                   is_local:1,
                                        is_static:1,
+                                       is_sticky:1,
                                        added_by_user:1,
                                        added_by_external_learn:1,
                                        offloaded:1;