[BRIDGE]: netfilter handle RCU during removal

Bridge netfilter code needs to handle the case where device is
removed from bridge while packet in process. In these cases the
bridge_parent can become null while processing.

This should fix: http://bugzilla.kernel.org/show_bug.cgi?id=5803

Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/bridge/br_netfilter.c b/net/bridge/br_netfilter.c
index 7cac3fb9f8099151abcc63e561dab42f714d4340..b5018166b0e5d163716efb5194940a9a0ddf591d 100644 (file)
--- a/net/bridge/br_netfilter.c
+++ b/net/bridge/br_netfilter.c
@@ -51,9 +51,6 @@
 #define store_orig_dstaddr(skb)         (skb_origaddr(skb) = (skb)->nh.iph->daddr)
 #define dnat_took_place(skb)    (skb_origaddr(skb) != (skb)->nh.iph->daddr)
 
-#define has_bridge_parent(device)      ((device)->br_port != NULL)
-#define bridge_parent(device)          ((device)->br_port->br->dev)
-
 #ifdef CONFIG_SYSCTL
 static struct ctl_table_header *brnf_sysctl_header;
 static int brnf_call_iptables = 1;
@@ -98,6 +95,12 @@ static struct rtable __fake_rtable = {
        .rt_flags       = 0,
 };
 
+static inline struct net_device *bridge_parent(const struct net_device *dev)
+{
+       struct net_bridge_port *port = rcu_dereference(dev->br_port);
+
+       return port ? port->br->dev : NULL;
+}
 
 /* PF_BRIDGE/PRE_ROUTING *********************************************/
 /* Undo the changes made for ip6tables PREROUTING and continue the
@@ -189,11 +192,15 @@ static int br_nf_pre_routing_finish_bridge(struct sk_buff *skb)
        skb->nf_bridge->mask ^= BRNF_NF_BRIDGE_PREROUTING;
 
        skb->dev = bridge_parent(skb->dev);
-       if (skb->protocol == __constant_htons(ETH_P_8021Q)) {
-               skb_pull(skb, VLAN_HLEN);
-               skb->nh.raw += VLAN_HLEN;
+       if (!skb->dev)
+               kfree_skb(skb);
+       else {
+               if (skb->protocol == __constant_htons(ETH_P_8021Q)) {
+                       skb_pull(skb, VLAN_HLEN);
+                       skb->nh.raw += VLAN_HLEN;
+               }
+               skb->dst->output(skb);
        }
-       skb->dst->output(skb);
        return 0;
 }
 
@@ -270,7 +277,7 @@ bridged_dnat:
 }
 
 /* Some common code for IPv4/IPv6 */
-static void setup_pre_routing(struct sk_buff *skb)
+static struct net_device *setup_pre_routing(struct sk_buff *skb)
 {
        struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 
@@ -282,6 +289,8 @@ static void setup_pre_routing(struct sk_buff *skb)
        nf_bridge->mask |= BRNF_NF_BRIDGE_PREROUTING;
        nf_bridge->physindev = skb->dev;
        skb->dev = bridge_parent(skb->dev);
+
+       return skb->dev;
 }
 
 /* We only check the length. A bridge shouldn't do any hop-by-hop stuff anyway */
@@ -376,7 +385,8 @@ static unsigned int br_nf_pre_routing_ipv6(unsigned int hook,
        nf_bridge_put(skb->nf_bridge);
        if ((nf_bridge = nf_bridge_alloc(skb)) == NULL)
                return NF_DROP;
-       setup_pre_routing(skb);
+       if (!setup_pre_routing(skb))
+               return NF_DROP;
 
        NF_HOOK(PF_INET6, NF_IP6_PRE_ROUTING, skb, skb->dev, NULL,
                br_nf_pre_routing_finish_ipv6);
@@ -465,7 +475,8 @@ static unsigned int br_nf_pre_routing(unsigned int hook, struct sk_buff **pskb,
        nf_bridge_put(skb->nf_bridge);
        if ((nf_bridge = nf_bridge_alloc(skb)) == NULL)
                return NF_DROP;
-       setup_pre_routing(skb);
+       if (!setup_pre_routing(skb))
+               return NF_DROP;
        store_orig_dstaddr(skb);
 
        NF_HOOK(PF_INET, NF_IP_PRE_ROUTING, skb, skb->dev, NULL,
@@ -539,11 +550,16 @@ static unsigned int br_nf_forward_ip(unsigned int hook, struct sk_buff **pskb,
        struct sk_buff *skb = *pskb;
        struct nf_bridge_info *nf_bridge;
        struct vlan_ethhdr *hdr = vlan_eth_hdr(skb);
+       struct net_device *parent;
        int pf;
 
        if (!skb->nf_bridge)
                return NF_ACCEPT;
 
+       parent = bridge_parent(out);
+       if (!parent)
+               return NF_DROP;
+
        if (skb->protocol == __constant_htons(ETH_P_IP) || IS_VLAN_IP)
                pf = PF_INET;
        else
@@ -564,8 +580,8 @@ static unsigned int br_nf_forward_ip(unsigned int hook, struct sk_buff **pskb,
        nf_bridge->mask |= BRNF_BRIDGED;
        nf_bridge->physoutdev = skb->dev;
 
-       NF_HOOK(pf, NF_IP_FORWARD, skb, bridge_parent(in),
-               bridge_parent(out), br_nf_forward_finish);
+       NF_HOOK(pf, NF_IP_FORWARD, skb, bridge_parent(in), parent,
+               br_nf_forward_finish);
 
        return NF_STOLEN;
 }
@@ -688,6 +704,8 @@ static unsigned int br_nf_local_out(unsigned int hook, struct sk_buff **pskb,
                goto out;
        }
        realoutdev = bridge_parent(skb->dev);
+       if (!realoutdev)
+               return NF_DROP;
 
 #if defined(CONFIG_VLAN_8021Q) || defined(CONFIG_VLAN_8021Q_MODULE)
        /* iptables should match -o br0.x */
@@ -701,9 +719,11 @@ static unsigned int br_nf_local_out(unsigned int hook, struct sk_buff **pskb,
        /* IP forwarded traffic has a physindev, locally
         * generated traffic hasn't. */
        if (realindev != NULL) {
-               if (!(nf_bridge->mask & BRNF_DONT_TAKE_PARENT) &&
-                   has_bridge_parent(realindev))
-                       realindev = bridge_parent(realindev);
+               if (!(nf_bridge->mask & BRNF_DONT_TAKE_PARENT) ) {
+                       struct net_device *parent = bridge_parent(realindev);
+                       if (parent)
+                               realindev = parent;
+               }
 
                NF_HOOK_THRESH(pf, NF_IP_FORWARD, skb, realindev,
                               realoutdev, br_nf_local_out_finish,
@@ -743,6 +763,9 @@ static unsigned int br_nf_post_routing(unsigned int hook, struct sk_buff **pskb,
        if (!nf_bridge)
                return NF_ACCEPT;
 
+       if (!realoutdev)
+               return NF_DROP;
+
        if (skb->protocol == __constant_htons(ETH_P_IP) || IS_VLAN_IP)
                pf = PF_INET;
        else