[NETFILTER]: nf_queue: Use RCU and mutex for queue handlers

Queue handlers are registered/unregistered in only process context.

Signed-off-by: Yasuyuki Kozakai <yasuyuki.kozakai@toshiba.co.jp>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 29 insertions, 23 deletions

diff --git a/net/netfilter/nf_queue.c b/net/netfilter/nf_queue.c
index f402894d7e72..823fbf404566 100644
--- a/net/netfilter/nf_queue.c
+++ b/net/netfilter/nf_queue.c
@@ -17,7 +17,7 @@
  */
 static struct nf_queue_handler *queue_handler[NPROTO];
 
-static DEFINE_RWLOCK(queue_handler_lock);
+static DEFINE_MUTEX(queue_handler_mutex);
 
 /* return EBUSY when somebody else is registered, return EEXIST if the
  * same handler is registered, return 0 in case of success. */
@@ -28,16 +28,16 @@ int nf_register_queue_handler(int pf, struct nf_queue_handler *qh)
         if (pf >= NPROTO)
                 return -EINVAL;
 
-        write_lock_bh(&queue_handler_lock);
+        mutex_lock(&queue_handler_mutex);
         if (queue_handler[pf] == qh)
                 ret = -EEXIST;
         else if (queue_handler[pf])
                 ret = -EBUSY;
         else {
-                queue_handler[pf] = qh;
+                rcu_assign_pointer(queue_handler[pf], qh);
                 ret = 0;
         }
-        write_unlock_bh(&queue_handler_lock);
+        mutex_unlock(&queue_handler_mutex);
 
         return ret;
 }
@@ -49,14 +49,16 @@ int nf_unregister_queue_handler(int pf, struct nf_queue_handler *qh)
         if (pf >= NPROTO)
                 return -EINVAL;
 
-        write_lock_bh(&queue_handler_lock);
+        mutex_lock(&queue_handler_mutex);
         if (queue_handler[pf] != qh) {
-                write_unlock_bh(&queue_handler_lock);
+                mutex_unlock(&queue_handler_mutex);
                 return -EINVAL;
         }
 
-        queue_handler[pf] = NULL;
-        write_unlock_bh(&queue_handler_lock);
+        rcu_assign_pointer(queue_handler[pf], NULL);
+        mutex_unlock(&queue_handler_mutex);
+
+        synchronize_rcu();
 
         return 0;
 }
@@ -66,12 +68,14 @@ void nf_unregister_queue_handlers(struct nf_queue_handler *qh)
 {
         int pf;
 
-        write_lock_bh(&queue_handler_lock);
+        mutex_lock(&queue_handler_mutex);
         for (pf = 0; pf < NPROTO; pf++)  {
                 if (queue_handler[pf] == qh)
-                        queue_handler[pf] = NULL;
+                        rcu_assign_pointer(queue_handler[pf], NULL);
         }
-        write_unlock_bh(&queue_handler_lock);
+        mutex_unlock(&queue_handler_mutex);
+
+        synchronize_rcu();
 }
 EXPORT_SYMBOL_GPL(nf_unregister_queue_handlers);
 
@@ -94,18 +98,21 @@ static int __nf_queue(struct sk_buff *skb,
         struct net_device *physoutdev = NULL;
 #endif
         struct nf_afinfo *afinfo;
+        struct nf_queue_handler *qh;
 
         /* QUEUE == DROP if noone is waiting, to be safe. */
-        read_lock(&queue_handler_lock);
-        if (!queue_handler[pf]) {
-                read_unlock(&queue_handler_lock);
+        rcu_read_lock();
+
+        qh = rcu_dereference(queue_handler[pf]);
+        if (!qh) {
+                rcu_read_unlock();
                 kfree_skb(skb);
                 return 1;
         }
 
         afinfo = nf_get_afinfo(pf);
         if (!afinfo) {
-                read_unlock(&queue_handler_lock);
+                rcu_read_unlock();
                 kfree_skb(skb);
                 return 1;
         }
@@ -115,7 +122,7 @@ static int __nf_queue(struct sk_buff *skb,
                 if (net_ratelimit())
                         printk(KERN_ERR "OOM queueing packet %p\n",
                                skb);
-                read_unlock(&queue_handler_lock);
+                rcu_read_unlock();
                 kfree_skb(skb);
                 return 1;
         }
@@ -125,7 +132,7 @@ static int __nf_queue(struct sk_buff *skb,
 
         /* If it's going away, ignore hook. */
         if (!try_module_get(info->elem->owner)) {
-                read_unlock(&queue_handler_lock);
+                rcu_read_unlock();
                 kfree(info);
                 return 0;
         }
@@ -143,10 +150,9 @@ static int __nf_queue(struct sk_buff *skb,
         }
 #endif
         afinfo->saveroute(skb, info);
-        status = queue_handler[pf]->outfn(skb, info, queuenum,
-                                          queue_handler[pf]->data);
+        status = qh->outfn(skb, info, queuenum, qh->data);
 
-        read_unlock(&queue_handler_lock);
+        rcu_read_unlock();
 
         if (status < 0) {
                 /* James M doesn't say fuck enough. */
@@ -313,13 +319,13 @@ static int seq_show(struct seq_file *s, void *v)
         loff_t *pos = v;
         struct nf_queue_handler *qh;
 
-        read_lock_bh(&queue_handler_lock);
-        qh = queue_handler[*pos];
+        rcu_read_lock();
+        qh = rcu_dereference(queue_handler[*pos]);
         if (!qh)
                 ret = seq_printf(s, "%2lld NONE\n", *pos);
         else
                 ret = seq_printf(s, "%2lld %s\n", *pos, qh->name);
-        read_unlock_bh(&queue_handler_lock);
+        rcu_read_unlock();
 
         return ret;
 }