Subject: [PATCH RFC v2 net-next 15/25] net/namespace: Update rtnl_net_dumpid to support NLM_F_DUMP_PROPER_HDR

From: David Ahern <[email-masked]>
Date: Mon, 1 Oct 2018 17:28:41 -0700

From: David Ahern <[email-masked]>

Update rtnl_net_dumpid to check for NLM_F_DUMP_PROPER_HDR in the netlink
message header. The dump request is expected to have an rtgenmsg struct
which has the family as the only element. No data may be appended.

Signed-off-by: David Ahern <[email-masked]>
---
 net/core/net_namespace.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/net/core/net_namespace.c b/net/core/net_namespace.c
index 670c84b1bfc2..0c3a978efc57 100644
--- a/net/core/net_namespace.c
+++ b/net/core/net_namespace.c
@@ -844,6 +844,7 @@ static int rtnl_net_dumpid_one(int id, void *peer, void *data)
 
 static int rtnl_net_dumpid(struct sk_buff *skb, struct netlink_callback *cb)
 {
+	const struct nlmsghdr *nlh = cb->nlh;
 	struct net *net = sock_net(skb->sk);
 	struct rtnl_net_dump_cb net_cb = {
 		.net = net,
@@ -853,6 +854,13 @@ static int rtnl_net_dumpid(struct sk_buff *skb, struct netlink_callback *cb)
 		.s_idx = cb->args[0],
 	};
 
+	if (nlh->nlmsg_flags & NLM_F_DUMP_PROPER_HDR) {
+		if (nlh->nlmsg_len != nlmsg_msg_size(sizeof(struct rtgenmsg))) {
+			NL_SET_ERR_MSG(cb->extack, "Unknown data in dump request");
+			return -EINVAL;
+		}
+	}
+
 	spin_lock_bh(&net->nsid_lock);
 	idr_for_each(&net->netns_ids, rtnl_net_dumpid_one, &net_cb);
 	spin_unlock_bh(&net->nsid_lock);
-- 
2.11.0