netns: fix NLM_F_ECHO mechanism for RTM_NEWNSID

The flag NLM_F_ECHO aims to reply to the user the message notified to all
listeners.
It was not the case with the command RTM_NEWNSID, let's fix this.

Fixes: 0c7aecd4 ("netns: add rtnl cmd to add and get peer netns ids")
Reported-by: Guillaume Nault <gnault@redhat.com>
Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
Acked-by: Guillaume Nault <gnault@redhat.com>
Tested-by: Guillaume Nault <gnault@redhat.com>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>

net/core/net_namespace.c

@@ -245,7 +245,8 @@ static int __peernet2id(struct net *net, struct net *peer)
 	return __peernet2id_alloc(net, peer, &no);
 }
 
-static void rtnl_net_notifyid(struct net *net, int cmd, int id);
+static void rtnl_net_notifyid(struct net *net, int cmd, int id, u32 portid,
+			      struct nlmsghdr *nlh);
 /* This function returns the id of a peer netns. If no id is assigned, one will
  * be allocated and returned.
  */
@@ -268,7 +269,7 @@ int peernet2id_alloc(struct net *net, struct net *peer)
 	id = __peernet2id_alloc(net, peer, &alloc);
 	spin_unlock_bh(&net->nsid_lock);
 	if (alloc && id >= 0)
-		rtnl_net_notifyid(net, RTM_NEWNSID, id);
+		rtnl_net_notifyid(net, RTM_NEWNSID, id, 0, NULL);
 	if (alive)
 		put_net(peer);
 	return id;
@@ -532,7 +533,7 @@ static void unhash_nsid(struct net *net, struct net *last)
 			idr_remove(&tmp->netns_ids, id);
 		spin_unlock_bh(&tmp->nsid_lock);
 		if (id >= 0)
-			rtnl_net_notifyid(tmp, RTM_DELNSID, id);
+			rtnl_net_notifyid(tmp, RTM_DELNSID, id, 0, NULL);
 		if (tmp == last)
 			break;
 	}
@@ -764,7 +765,8 @@ static int rtnl_net_newid(struct sk_buff *skb, struct nlmsghdr *nlh,
 	err = alloc_netid(net, peer, nsid);
 	spin_unlock_bh(&net->nsid_lock);
 	if (err >= 0) {
-		rtnl_net_notifyid(net, RTM_NEWNSID, err);
+		rtnl_net_notifyid(net, RTM_NEWNSID, err, NETLINK_CB(skb).portid,
+				  nlh);
 		err = 0;
 	} else if (err == -ENOSPC && nsid >= 0) {
 		err = -EEXIST;
@@ -1051,9 +1053,12 @@ static int rtnl_net_dumpid(struct sk_buff *skb, struct netlink_callback *cb)
 	return err < 0 ? err : skb->len;
 }
 
-static void rtnl_net_notifyid(struct net *net, int cmd, int id)
+static void rtnl_net_notifyid(struct net *net, int cmd, int id, u32 portid,
+			      struct nlmsghdr *nlh)
 {
 	struct net_fill_args fillargs = {
+		.portid = portid,
+		.seq = nlh ? nlh->nlmsg_seq : 0,
 		.cmd = cmd,
 		.nsid = id,
 	};
@@ -1068,7 +1073,7 @@ static void rtnl_net_notifyid(struct net *net, int cmd, int id)
 	if (err < 0)
 		goto err_out;
 
-	rtnl_notify(msg, net, 0, RTNLGRP_NSID, NULL, 0);
+	rtnl_notify(msg, net, portid, RTNLGRP_NSID, nlh, 0);
 	return;
 
 err_out: