net: rtnetlink notify events for FDB NTF_SELF adds and deletes

It is useful to be able to monitor for FDB events in user space.
This patch adds support to generate netlink events when a change
is made to a device supporting the FDB ops.

This brings embedded switches inline with the SW net/bridge which
triggers events on FDB updates as well.

Signed-off-by: John Fastabend <john.r.fastabend@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index e8488c7b092ce2066e5c4092ff43419bd8caa425..b442d35bbc8bbc1e96e008c77ef65a747e4e5eae 100644 (file)
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -2011,6 +2011,33 @@ nla_put_failure:
        return -EMSGSIZE;
 }
 
+static inline size_t rtnl_fdb_nlmsg_size(void)
+{
+       return NLMSG_ALIGN(sizeof(struct ndmsg)) + nla_total_size(ETH_ALEN);
+}
+
+static void rtnl_fdb_notify(struct net_device *dev, u8 *addr, int type)
+{
+       struct net *net = dev_net(dev);
+       struct sk_buff *skb;
+       int err = -ENOBUFS;
+
+       skb = nlmsg_new(rtnl_fdb_nlmsg_size(), GFP_ATOMIC);
+       if (!skb)
+               goto errout;
+
+       err = nlmsg_populate_fdb_fill(skb, dev, addr, 0, 0, type, NTF_SELF);
+       if (err < 0) {
+               kfree_skb(skb);
+               goto errout;
+       }
+
+       rtnl_notify(skb, net, 0, RTNLGRP_NEIGH, NULL, GFP_ATOMIC);
+       return;
+errout:
+       rtnl_set_sk_err(net, RTNLGRP_NEIGH, err);
+}
+
 static int rtnl_fdb_add(struct sk_buff *skb, struct nlmsghdr *nlh, void *arg)
 {
        struct net *net = sock_net(skb->sk);
@@ -2067,8 +2094,10 @@ static int rtnl_fdb_add(struct sk_buff *skb, struct nlmsghdr *nlh, void *arg)
                err = dev->netdev_ops->ndo_fdb_add(ndm, dev, addr,
                                                   nlh->nlmsg_flags);
 
-               if (!err)
+               if (!err) {
+                       rtnl_fdb_notify(dev, addr, RTM_NEWNEIGH);
                        ndm->ndm_flags &= ~NTF_SELF;
+               }
        }
 out:
        return err;
@@ -2125,8 +2154,10 @@ static int rtnl_fdb_del(struct sk_buff *skb, struct nlmsghdr *nlh, void *arg)
        if ((ndm->ndm_flags & NTF_SELF) && dev->netdev_ops->ndo_fdb_del) {
                err = dev->netdev_ops->ndo_fdb_del(ndm, dev, addr);
 
-               if (!err)
+               if (!err) {
+                       rtnl_fdb_notify(dev, addr, RTM_DELNEIGH);
                        ndm->ndm_flags &= ~NTF_SELF;
+               }
        }
 out:
        return err;