netfilter: ctnetlink: cleanup conntrack update preliminary checkings

This patch moves the preliminary checkings that must be fulfilled
to update a conntrack, which are the following:

 * NAT manglings cannot be updated
 * Changing the master conntrack is not allowed.

This patch is a cleanup.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Patrick McHardy <kaber@trash.net>

1 files changed, 4 insertions, 11 deletions

diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c
index cca22d55382..b67db695d83 100644
--- a/net/netfilter/nf_conntrack_netlink.c
+++ b/net/netfilter/nf_conntrack_netlink.c
@@ -1062,6 +1062,10 @@ ctnetlink_change_conntrack(struct nf_conn *ct, struct nlattr *cda[])
 {
         int err;
 
+        /* only allow NAT changes and master assignation for new conntracks */
+        if (cda[CTA_NAT_SRC] || cda[CTA_NAT_DST] || cda[CTA_TUPLE_MASTER])
+                return -EOPNOTSUPP;
+
         if (cda[CTA_HELP]) {
                 err = ctnetlink_change_helper(ct, cda);
                 if (err < 0)
@@ -1323,17 +1327,6 @@ ctnetlink_new_conntrack(struct sock *ctnl, struct sk_buff *skb,
         if (!(nlh->nlmsg_flags & NLM_F_EXCL)) {
                 struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(h);
 
-                /* we only allow nat config for new conntracks */
-                if (cda[CTA_NAT_SRC] || cda[CTA_NAT_DST]) {
-                        err = -EOPNOTSUPP;
-                        goto out_unlock;
-                }
-                /* can't link an existing conntrack to a master */
-                if (cda[CTA_TUPLE_MASTER]) {
-                        err = -EOPNOTSUPP;
-                        goto out_unlock;
-                }
-
                 err = ctnetlink_change_conntrack(ct, cda);
                 if (err == 0) {
                         nf_conntrack_get(&ct->ct_general);