netns: allow to dump netns ids

Which this patch, it's possible to dump the list of ids allocated for peer
netns.

Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 48 insertions, 1 deletions

diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
index b3b5f22f0e90..a3abb719221f 100644
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -616,6 +616,52 @@ out:
         return err;
 }
 
+struct rtnl_net_dump_cb {
+        struct net *net;
+        struct sk_buff *skb;
+        struct netlink_callback *cb;
+        int idx;
+        int s_idx;
+};
+
+static int rtnl_net_dumpid_one(int id, void *peer, void *data)
+{
+        struct rtnl_net_dump_cb *net_cb = (struct rtnl_net_dump_cb *)data;
+        int ret;
+
+        if (net_cb->idx < net_cb->s_idx)
+                goto cont;
+
+        ret = rtnl_net_fill(net_cb->skb, NETLINK_CB(net_cb->cb->skb).portid,
+                            net_cb->cb->nlh->nlmsg_seq, NLM_F_MULTI,
+                            RTM_NEWNSID, net_cb->net, peer, id);
+        if (ret < 0)
+                return ret;
+
+cont:
+        net_cb->idx++;
+        return 0;
+}
+
+static int rtnl_net_dumpid(struct sk_buff *skb, struct netlink_callback *cb)
+{
+        struct net *net = sock_net(skb->sk);
+        struct rtnl_net_dump_cb net_cb = {
+                .net = net,
+                .skb = skb,
+                .cb = cb,
+                .idx = 0,
+                .s_idx = cb->args[0],
+        };
+
+        ASSERT_RTNL();
+
+        idr_for_each(&net->netns_ids, rtnl_net_dumpid_one, &net_cb);
+
+        cb->args[0] = net_cb.idx;
+        return skb->len;
+}
+
 static void rtnl_net_notifyid(struct net *net, struct net *peer, int cmd,
                               int id)
 {
@@ -673,7 +719,8 @@ static int __init net_ns_init(void)
         register_pernet_subsys(&net_ns_ops);
 
         rtnl_register(PF_UNSPEC, RTM_NEWNSID, rtnl_net_newid, NULL, NULL);
-        rtnl_register(PF_UNSPEC, RTM_GETNSID, rtnl_net_getid, NULL, NULL);
+        rtnl_register(PF_UNSPEC, RTM_GETNSID, rtnl_net_getid, rtnl_net_dumpid,
+                      NULL);
 
         return 0;
 }