[PATCH] xt_hashlimit fix BUG()

["Vitaly E. Lavrov" <lve@xxxxxxx>]

The following patch fixes a bug in xt_hashlimit.
Bug appears at the end of work the networks namespace, provided that the 
tables (filter/mangle/raw) have rule  with xt_hashlimit.
The error occurs because the __net_exit hashlimit_net_exit() is executed 
before the tables are cleared.
Change this order of calls is impossible, since tables must be 
registered earlier than extensions.
Bug exists in all versions of the kernel since 2.6.35

Cleaning tables before completing the network namespace can be used as a 
workaround.

Idea of the patch that if the files are deleted from the directory 
/proc/net/ip[6]t_hashlimit/" procedure XXXXX, then a flag is set "clean".
If cleaning the tables occurs later and the flag "clean" is set, then 
the delete files is skipped.

Patch for kernel 3.4.22

Signed-off-by: Vitaly Lavrov lve@xxxxxxx

---
diff --git a/net/netfilter/xt_hashlimit.c b/net/netfilter/xt_hashlimit.c
index 2195eb0..5416185 100644
--- a/net/netfilter/xt_hashlimit.c
+++ b/net/netfilter/xt_hashlimit.c
@@ -46,6 +46,7 @@ struct hashlimit_net {
        struct hlist_head       htables;
        struct proc_dir_entry   *ipt_hashlimit;
        struct proc_dir_entry   *ip6t_hashlimit;
+       int                     clean;
 };

 static int hashlimit_net_id;
@@ -319,7 +320,8 @@ static void htable_destroy(struct 
xt_hashlimit_htable *hinfo)
                parent = hashlimit_net->ipt_hashlimit;
        else
                parent = hashlimit_net->ip6t_hashlimit;
-       remove_proc_entry(hinfo->pde->name, parent);
+       if(!hashlimit_net->clean)
+               remove_proc_entry(hinfo->pde->name, parent);
        htable_selective_cleanup(hinfo, select_all);
        vfree(hinfo);
 }
@@ -784,6 +786,7 @@ static int __net_init hashlimit_net_init(struct net 
*net)
 {
        struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);

+       hashlimit_net->clean = 0;
        INIT_HLIST_HEAD(&hashlimit_net->htables);
        return hashlimit_proc_net_init(net);
 }
@@ -791,8 +794,19 @@ static int __net_init hashlimit_net_init(struct net 
*net)
 static void __net_exit hashlimit_net_exit(struct net *net)
 {
        struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
+       struct xt_hashlimit_htable *hinfo;
+       struct hlist_node *pos;
+       struct proc_dir_entry *pde;
+
+       mutex_lock(&hashlimit_mutex);
+       hashlimit_net->clean = 1;
+       pde = hashlimit_net->ipt_hashlimit;
+       if(!pde) pde = hashlimit_net->ip6t_hashlimit;
+       hlist_for_each_entry(hinfo, pos, &hashlimit_net->htables, node) {
+               remove_proc_entry(hinfo->pde->name,pde);
+       }
+       mutex_unlock(&hashlimit_mutex);

-       BUG_ON(!hlist_empty(&hashlimit_net->htables));
        hashlimit_proc_net_exit(net);
 }
--

diff --git a/net/netfilter/xt_hashlimit.c b/net/netfilter/xt_hashlimit.c
index 2195eb0..5416185 100644
--- a/net/netfilter/xt_hashlimit.c
+++ b/net/netfilter/xt_hashlimit.c
@@ -46,6 +46,7 @@ struct hashlimit_net {
 	struct hlist_head	htables;
 	struct proc_dir_entry	*ipt_hashlimit;
 	struct proc_dir_entry	*ip6t_hashlimit;
+	int			clean;
 };
 
 static int hashlimit_net_id;
@@ -319,7 +320,8 @@ static void htable_destroy(struct xt_hashlimit_htable *hinfo)
 		parent = hashlimit_net->ipt_hashlimit;
 	else
 		parent = hashlimit_net->ip6t_hashlimit;
-	remove_proc_entry(hinfo->pde->name, parent);
+	if(!hashlimit_net->clean)
+		remove_proc_entry(hinfo->pde->name, parent);
 	htable_selective_cleanup(hinfo, select_all);
 	vfree(hinfo);
 }
@@ -784,6 +786,7 @@ static int __net_init hashlimit_net_init(struct net *net)
 {
 	struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
 
+	hashlimit_net->clean = 0;
 	INIT_HLIST_HEAD(&hashlimit_net->htables);
 	return hashlimit_proc_net_init(net);
 }
@@ -791,8 +794,19 @@ static int __net_init hashlimit_net_init(struct net *net)
 static void __net_exit hashlimit_net_exit(struct net *net)
 {
 	struct hashlimit_net *hashlimit_net = hashlimit_pernet(net);
+	struct xt_hashlimit_htable *hinfo;
+	struct hlist_node *pos;
+	struct proc_dir_entry *pde;
+
+	mutex_lock(&hashlimit_mutex);
+	hashlimit_net->clean = 1;
+	pde = hashlimit_net->ipt_hashlimit;
+	if(!pde) pde = hashlimit_net->ip6t_hashlimit;
+	hlist_for_each_entry(hinfo, pos, &hashlimit_net->htables, node) {
+		remove_proc_entry(hinfo->pde->name,pde);
+	}
+	mutex_unlock(&hashlimit_mutex);
 
-	BUG_ON(!hlist_empty(&hashlimit_net->htables));
 	hashlimit_proc_net_exit(net);
 }