net: Add support for filtering neigh dump by master device

Add support for filtering neighbor dumps by master device by adding
the NDA_MASTER attribute to the dump request. A new netlink flag,
NLM_F_DUMP_FILTERED, is added to indicate the kernel supports the
request and output is filtered as requested.

Signed-off-by: David Ahern <dsa@cumulusnetworks.com>
Acked-by: Roopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/uapi/linux/netlink.h b/include/uapi/linux/netlink.h
index 6f3fe16..f095155 100644 (file)
--- a/include/uapi/linux/netlink.h
+++ b/include/uapi/linux/netlink.h
@@ -54,6 +54,7 @@ struct nlmsghdr {
 #define NLM_F_ACK              4       /* Reply with ack, with zero or error code */
 #define NLM_F_ECHO             8       /* Echo this request            */
 #define NLM_F_DUMP_INTR                16      /* Dump was inconsistent due to sequence change */
+#define NLM_F_DUMP_FILTERED    32      /* Dump was filtered as requested */
 
 /* Modifiers to GET request */
 #define NLM_F_ROOT     0x100   /* specify tree root    */

diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index 2b515ba..8c57fdf 100644 (file)
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -2235,14 +2235,42 @@ static void neigh_update_notify(struct neighbour *neigh)
        __neigh_notify(neigh, RTM_NEWNEIGH, 0);
 }
 
+static bool neigh_master_filtered(struct net_device *dev, int master_idx)
+{
+       struct net_device *master;
+
+       if (!master_idx)
+               return false;
+
+       master = netdev_master_upper_dev_get(dev);
+       if (!master || master->ifindex != master_idx)
+               return true;
+
+       return false;
+}
+
 static int neigh_dump_table(struct neigh_table *tbl, struct sk_buff *skb,
                            struct netlink_callback *cb)
 {
        struct net *net = sock_net(skb->sk);
+       const struct nlmsghdr *nlh = cb->nlh;
+       struct nlattr *tb[NDA_MAX + 1];
        struct neighbour *n;
        int rc, h, s_h = cb->args[1];
        int idx, s_idx = idx = cb->args[2];
        struct neigh_hash_table *nht;
+       int filter_master_idx = 0;
+       unsigned int flags = NLM_F_MULTI;
+       int err;
+
+       err = nlmsg_parse(nlh, sizeof(struct ndmsg), tb, NDA_MAX, NULL);
+       if (!err) {
+               if (tb[NDA_MASTER])
+                       filter_master_idx = nla_get_u32(tb[NDA_MASTER]);
+
+               if (filter_master_idx)
+                       flags |= NLM_F_DUMP_FILTERED;
+       }
 
        rcu_read_lock_bh();
        nht = rcu_dereference_bh(tbl->nht);
@@ -2255,12 +2283,14 @@ static int neigh_dump_table(struct neigh_table *tbl, struct sk_buff *skb,
                     n = rcu_dereference_bh(n->next)) {
                        if (!net_eq(dev_net(n->dev), net))
                                continue;
+                       if (neigh_master_filtered(n->dev, filter_master_idx))
+                               continue;
                        if (idx < s_idx)
                                goto next;
                        if (neigh_fill_info(skb, n, NETLINK_CB(cb->skb).portid,
                                            cb->nlh->nlmsg_seq,
                                            RTM_NEWNEIGH,
-                                           NLM_F_MULTI) < 0) {
+                                           flags) < 0) {
                                rc = -1;
                                goto out;
                        }