netfilter: ctnetlink: fix double helper assignation for NAT'ed conntracks

If we create a conntrack that has NAT handlings and a helper, the helper
is assigned twice. This happens because nf_nat_setup_info() - via
nf_conntrack_alter_reply() - sets the helper before ctnetlink, which
indeed does not check if the conntrack already has a helper as it thinks that
it is a brand new conntrack.

The fix moves the helper assignation before the set of the status flags.
This avoids a bogus assertion in __nf_ct_ext_add (if netfilter assertions are
enabled) which checks that the conntrack must not be confirmed.

This problem was introduced in 2.6.23 with the netfilter extension
infrastructure.

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

diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c
index 105a616..d1fb2f8 100644 (file)
--- a/net/netfilter/nf_conntrack_netlink.c
+++ b/net/netfilter/nf_conntrack_netlink.c
@@ -1136,16 +1136,33 @@ ctnetlink_create_conntrack(struct nlattr *cda[],
        ct->timeout.expires = jiffies + ct->timeout.expires * HZ;
        ct->status |= IPS_CONFIRMED;
 
+       rcu_read_lock();
+       helper = __nf_ct_helper_find(rtuple);
+       if (helper) {
+               help = nf_ct_helper_ext_add(ct, GFP_KERNEL);
+               if (help == NULL) {
+                       rcu_read_unlock();
+                       err = -ENOMEM;
+                       goto err;
+               }
+               /* not in hash table yet so not strictly necessary */
+               rcu_assign_pointer(help->helper, helper);
+       }
+
        if (cda[CTA_STATUS]) {
                err = ctnetlink_change_status(ct, cda);
-               if (err < 0)
+               if (err < 0) {
+                       rcu_read_unlock();
                        goto err;
+               }
        }
 
        if (cda[CTA_PROTOINFO]) {
                err = ctnetlink_change_protoinfo(ct, cda);
-               if (err < 0)
+               if (err < 0) {
+                       rcu_read_unlock();
                        goto err;
+               }
        }
 
        nf_ct_acct_ext_add(ct, GFP_KERNEL);
@@ -1155,19 +1172,6 @@ ctnetlink_create_conntrack(struct nlattr *cda[],
                ct->mark = ntohl(nla_get_be32(cda[CTA_MARK]));
 #endif
 
-       rcu_read_lock();
-       helper = __nf_ct_helper_find(rtuple);
-       if (helper) {
-               help = nf_ct_helper_ext_add(ct, GFP_KERNEL);
-               if (help == NULL) {
-                       rcu_read_unlock();
-                       err = -ENOMEM;
-                       goto err;
-               }
-               /* not in hash table yet so not strictly necessary */
-               rcu_assign_pointer(help->helper, helper);
-       }
-
        /* setup master conntrack: this is a confirmed expectation */
        if (master_ct) {
                __set_bit(IPS_EXPECTED_BIT, &ct->status);