[NETFILTER]: x_tables: return new table from {arp,ip,ip6}t_register_table()

Typical table module registers xt_table structure (i.e. packet_filter)
and link it to list during it. We can't use one template for it because
corresponding list_head will become corrupted. We also can't unregister
with template because it wasn't changed at all and thus doesn't know in
which list it is.

So, we duplicate template at the very first step of table registration.
Table modules will save it for use during unregistration time and actual
filtering.

Do it at once to not screw bisection.

P.S.: renaming i.e. packet_filter => __packet_filter is temporary until
      full netnsization of table modules is done.

Signed-off-by: Alexey Dobriyan <adobriyan@sw.ru>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 11 insertions, 1 deletions

diff --git a/net/netfilter/x_tables.c b/net/netfilter/x_tables.c
index d62f722ccccb..d7fbb1bb92ea 100644
--- a/net/netfilter/x_tables.c
+++ b/net/netfilter/x_tables.c
@@ -667,9 +667,16 @@ struct xt_table *xt_register_table(struct net *net, struct xt_table *table,
 	struct xt_table_info *private;
 	struct xt_table *t;
 
+	/* Don't add one object to multiple lists. */
+	table = kmemdup(table, sizeof(struct xt_table), GFP_KERNEL);
+	if (!table) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
 	ret = mutex_lock_interruptible(&xt[table->af].mutex);
 	if (ret != 0)
-		goto out;
+		goto out_free;
 
 	/* Don't autoload: we'd eat our tail... */
 	list_for_each_entry(t, &net->xt.tables[table->af], list) {
@@ -697,6 +704,8 @@ struct xt_table *xt_register_table(struct net *net, struct xt_table *table,
 
  unlock:
 	mutex_unlock(&xt[table->af].mutex);
+out_free:
+	kfree(table);
 out:
 	return ERR_PTR(ret);
 }
@@ -710,6 +719,7 @@ void *xt_unregister_table(struct xt_table *table)
 	private = table->private;
 	list_del(&table->list);
 	mutex_unlock(&xt[table->af].mutex);
+	kfree(table);
 
 	return private;
 }