net: bridge: fix flags interpretation for extern learn fdb entries

Ignore fdb flags when adding port extern learn entries and always set
BR_FDB_LOCAL flag when adding bridge extern learn entries. This is
closest to the behaviour we had before and avoids breaking any use cases
which were allowed.

This patch fixes iproute2 calls which assume NUD_PERMANENT and were
allowed before, example:
$ bridge fdb add 00:11:22:33:44:55 dev swp1 extern_learn

Extern learn entries are allowed to roam, but do not expire, so static
or dynamic flags make no sense for them.

Also add a comment for future reference.

Fixes: 576eeb71159b ("net: bridge: allow to add externally learned entries from user-space")
Fixes: d0ef242a926a ("net: bridge: validate the NUD_PERMANENT bit when adding an extern_learn FDB entry")
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Tested-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Nikolay Aleksandrov <nikolay@nvidia.com>
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Link: https://lore.kernel.org/r/20210810110010.43859-1-razor@blackwall.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/include/uapi/linux/neighbour.h b/include/uapi/linux/neighbour.h
index dc8b72201f6c5b19a96214f3029be292a3019665..00a60695fa5388f2150c111d23698cb7a0580d39 100644 (file)
--- a/include/uapi/linux/neighbour.h
+++ b/include/uapi/linux/neighbour.h
@@ -66,8 +66,11 @@ enum {
 #define NUD_NONE       0x00
 
 /* NUD_NOARP & NUD_PERMANENT are pseudostates, they never change
-   and make no address resolution or NUD.
-   NUD_PERMANENT also cannot be deleted by garbage collectors.
+ * and make no address resolution or NUD.
+ * NUD_PERMANENT also cannot be deleted by garbage collectors.
+ * When NTF_EXT_LEARNED is set for a bridge fdb entry the different cache entry
+ * states don't make sense and thus are ignored. Such entries don't age and
+ * can roam.
  */
 
 struct nda_cacheinfo {

diff --git a/net/bridge/br.c b/net/bridge/br.c
index bbab9984f24e5f60e81611ae1603c6c3b46a7eec..ef743f94254d76362ba15f60bccddd57e3fb6798 100644 (file)
--- a/net/bridge/br.c
+++ b/net/bridge/br.c
@@ -166,8 +166,7 @@ static int br_switchdev_event(struct notifier_block *unused,
        case SWITCHDEV_FDB_ADD_TO_BRIDGE:
                fdb_info = ptr;
                err = br_fdb_external_learn_add(br, p, fdb_info->addr,
-                                               fdb_info->vid,
-                                               fdb_info->is_local, false);
+                                               fdb_info->vid, false);
                if (err) {
                        err = notifier_from_errno(err);
                        break;

diff --git a/net/bridge/br_fdb.c b/net/bridge/br_fdb.c
index 835cec1e5a0357dc9faae2e2141665074032d236..5dee30966ed355fda199533104ccf2e1a591ac1a 100644 (file)
--- a/net/bridge/br_fdb.c
+++ b/net/bridge/br_fdb.c
@@ -1044,10 +1044,7 @@ static int __br_fdb_add(struct ndmsg *ndm, struct net_bridge *br,
                                           "FDB entry towards bridge must be permanent");
                        return -EINVAL;
                }
-
-               err = br_fdb_external_learn_add(br, p, addr, vid,
-                                               ndm->ndm_state & NUD_PERMANENT,
-                                               true);
+               err = br_fdb_external_learn_add(br, p, addr, vid, true);
        } else {
                spin_lock_bh(&br->hash_lock);
                err = fdb_add_entry(br, p, addr, ndm, nlh_flags, vid, nfea_tb);
@@ -1275,7 +1272,7 @@ void br_fdb_unsync_static(struct net_bridge *br, struct net_bridge_port *p)
 }
 
 int br_fdb_external_learn_add(struct net_bridge *br, struct net_bridge_port *p,
-                             const unsigned char *addr, u16 vid, bool is_local,
+                             const unsigned char *addr, u16 vid,
                              bool swdev_notify)
 {
        struct net_bridge_fdb_entry *fdb;
@@ -1293,7 +1290,7 @@ int br_fdb_external_learn_add(struct net_bridge *br, struct net_bridge_port *p,
                if (swdev_notify)
                        flags |= BIT(BR_FDB_ADDED_BY_USER);
 
-               if (is_local)
+               if (!p)
                        flags |= BIT(BR_FDB_LOCAL);
 
                fdb = fdb_create(br, p, addr, vid, flags);
@@ -1322,7 +1319,7 @@ int br_fdb_external_learn_add(struct net_bridge *br, struct net_bridge_port *p,
                if (swdev_notify)
                        set_bit(BR_FDB_ADDED_BY_USER, &fdb->flags);
 
-               if (is_local)
+               if (!p)
                        set_bit(BR_FDB_LOCAL, &fdb->flags);
 
                if (modified)

diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index aa64d8d63ca3fb03ed3578d54d8a3a3e87ab5039..2b48b204205e68dd2b092d61578b7b6ccb228487 100644 (file)
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -711,7 +711,7 @@ int br_fdb_get(struct sk_buff *skb, struct nlattr *tb[], struct net_device *dev,
 int br_fdb_sync_static(struct net_bridge *br, struct net_bridge_port *p);
 void br_fdb_unsync_static(struct net_bridge *br, struct net_bridge_port *p);
 int br_fdb_external_learn_add(struct net_bridge *br, struct net_bridge_port *p,
-                             const unsigned char *addr, u16 vid, bool is_local,
+                             const unsigned char *addr, u16 vid,
                              bool swdev_notify);
 int br_fdb_external_learn_del(struct net_bridge *br, struct net_bridge_port *p,
                              const unsigned char *addr, u16 vid,