batman-adv: Don't rely on NF_HOOKs return value
Commit Message
If a hook returns NF_STOLEN, neither batman_skb_recv nor
batman_skb_recv_finish free the skb due to the asynchronous netfilter
handling in the kernel. Therefore not batman_skb_recv but the ok
function batman_skb_recv_finish should do the freeing when a recv
subfunction returns NET_RX_DROP instead.
Reported-by: Vasiliy Kulikov <segooon@gmail.com>
Signed-off-by: Linus Lüssing <linus.luessing@web.de>
---
hard-interface.c | 80 +++++++++++++++++++++++++----------------------------
1 files changed, 38 insertions(+), 42 deletions(-)
Comments
On Sunday 22 August 2010 22:53:20 Linus Lüssing wrote:
> If a hook returns NF_STOLEN, neither batman_skb_recv nor
> batman_skb_recv_finish free the skb due to the asynchronous netfilter
> handling in the kernel. Therefore not batman_skb_recv but the ok
> function batman_skb_recv_finish should do the freeing when a recv
> subfunction returns NET_RX_DROP instead.
>
> Reported-by: Vasiliy Kulikov <segooon@gmail.com>
> Signed-off-by: Linus Lüssing <linus.luessing@web.de>
Patch has been applied (rev. 1780).
Thanks,
Marek
@@ -494,56 +494,27 @@ out:
static int batman_skb_recv_finish(struct sk_buff *skb)
{
- return NF_ACCEPT;
-}
-
-/* receive a packet with the batman ethertype coming on a hard
- * interface */
-int batman_skb_recv(struct sk_buff *skb, struct net_device *dev,
- struct packet_type *ptype, struct net_device *orig_dev)
-{
- struct bat_priv *bat_priv;
struct batman_packet *batman_packet;
struct batman_if *batman_if;
+ struct bat_priv *bat_priv;
int ret;
- batman_if = container_of(ptype, struct batman_if, batman_adv_ptype);
- skb = skb_share_check(skb, GFP_ATOMIC);
-
- /* skb was released by skb_share_check() */
- if (!skb)
- goto err_out;
-
- /* if netfilter/ebtables wants to block incoming batman
- * packets then give them a chance to do so here */
- ret = NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_IN, skb, dev, NULL,
- batman_skb_recv_finish);
- if (ret != 1)
- goto err_out;
-
- /* packet should hold at least type and version */
- if (unlikely(!pskb_may_pull(skb, 2)))
+ batman_if = get_batman_if_by_netdev(skb->dev);
+ if (!batman_if)
goto err_free;
- /* expect a valid ethernet header here. */
- if (unlikely(skb->mac_len != sizeof(struct ethhdr)
- || !skb_mac_header(skb)))
+ if (!batman_if->soft_iface)
goto err_free;
- if (!batman_if->soft_iface)
+ /* discard frames on not active interfaces */
+ if (batman_if->if_status != IF_ACTIVE)
goto err_free;
bat_priv = netdev_priv(batman_if->soft_iface);
-
if (atomic_read(&bat_priv->mesh_state) != MESH_ACTIVE)
goto err_free;
- /* discard frames on not active interfaces */
- if (batman_if->if_status != IF_ACTIVE)
- goto err_free;
-
batman_packet = (struct batman_packet *)skb->data;
-
if (batman_packet->version != COMPAT_VERSION) {
bat_dbg(DBG_BATMAN, bat_priv,
"Drop packet: incompatible batman version (%i)\n",
@@ -551,6 +522,7 @@ int batman_skb_recv(struct sk_buff *skb, struct net_device *dev,
goto err_free;
}
+
/* all receive handlers return whether they received or reused
* the supplied skb. if not, we have to free the skb. */
@@ -589,18 +561,42 @@ int batman_skb_recv(struct sk_buff *skb, struct net_device *dev,
}
if (ret == NET_RX_DROP)
- kfree_skb(skb);
+ goto err_free;
- /* return NET_RX_SUCCESS in any case as we
- * most probably dropped the packet for
- * routing-logical reasons. */
+ return 0;
- return NET_RX_SUCCESS;
+err_free:
+ kfree_skb(skb);
+ return 0;
+}
+/* receive a packet with the batman ethertype coming on a hard
+ * interface */
+int batman_skb_recv(struct sk_buff *skb, struct net_device *dev,
+ struct packet_type *ptype, struct net_device *orig_dev)
+{
+ skb = skb_share_check(skb, GFP_ATOMIC);
+
+ /* skb was released by skb_share_check() */
+ if (!skb)
+ return 0;
+
+ /* packet should hold at least type and version */
+ if (unlikely(!pskb_may_pull(skb, 2)))
+ goto err_free;
+
+ /* expect a valid ethernet header here. */
+ if (unlikely(skb->mac_len != sizeof(struct ethhdr)
+ || !skb_mac_header(skb)))
+ goto err_free;
+
+ /* if netfilter/ebtables wants to block incoming batman
+ * packets then give them a chance to do so here */
+ return NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_IN, skb, dev, NULL,
+ batman_skb_recv_finish);
err_free:
kfree_skb(skb);
-err_out:
- return NET_RX_DROP;
+ return 0;
}
struct notifier_block hard_if_notifier = {