The ebtables brouting chain, traversed through the call
br_should_route_hook(), can alter a packet. The redirect target
does this, f.e., to change the MAC destination.
Bart discovered this and proposed a patch; this is a revised version.
This version cleans up the handle_bridge code in net/core/dev.c as well
as getting rid of extra rcu_read_lock and only does the br_port checking
once.
Signed-off-by: Stephen Hemminger <shemminger@xxxxxxxx>
diff -Nru a/include/linux/if_bridge.h b/include/linux/if_bridge.h
--- a/include/linux/if_bridge.h 2004-08-25 14:10:43 -07:00
+++ b/include/linux/if_bridge.h 2004-08-25 14:10:43 -07:00
@@ -105,7 +105,7 @@
#include <linux/netdevice.h>
extern void brioctl_set(int (*ioctl_hook)(unsigned int, void __user *));
-extern int (*br_handle_frame_hook)(struct sk_buff *skb);
+extern int (*br_handle_frame_hook)(struct net_bridge_port *p, struct sk_buff
**pskb);
extern int (*br_should_route_hook)(struct sk_buff **pskb);
#endif
diff -Nru a/net/bridge/br_input.c b/net/bridge/br_input.c
--- a/net/bridge/br_input.c 2004-08-25 14:10:43 -07:00
+++ b/net/bridge/br_input.c 2004-08-25 14:10:43 -07:00
@@ -45,26 +45,15 @@
br_pass_frame_up_finish);
}
+/* note: already called with rcu_read_lock (preempt_disabled) */
int br_handle_frame_finish(struct sk_buff *skb)
{
- struct net_bridge *br;
- unsigned char *dest;
+ const unsigned char *dest = skb->mac.ethernet->h_dest;
+ struct net_bridge_port *p = skb->dev->br_port;
+ struct net_bridge *br = p->br;
struct net_bridge_fdb_entry *dst;
- struct net_bridge_port *p;
- int passedup;
+ int passedup = 0;
- dest = skb->mac.ethernet->h_dest;
-
- rcu_read_lock();
- p = rcu_dereference(skb->dev->br_port);
-
- if (p == NULL || p->state == BR_STATE_DISABLED) {
- kfree_skb(skb);
- goto out;
- }
-
- br = p->br;
- passedup = 0;
if (br->dev->flags & IFF_PROMISC) {
struct sk_buff *skb2;
@@ -99,20 +88,21 @@
br_flood_forward(br, skb, 0);
out:
- rcu_read_unlock();
return 0;
}
-int br_handle_frame(struct sk_buff *skb)
+/*
+ * Called via br_handle_frame_hook.
+ * Return 0 if *pskb should be processed furthur
+ * 1 if *pskb is handled
+ * note: already called with rcu_read_lock (preempt_disabled)
+ */
+int br_handle_frame(struct net_bridge_port *p, struct sk_buff **pskb)
{
- unsigned char *dest;
- struct net_bridge_port *p;
-
- dest = skb->mac.ethernet->h_dest;
+ struct sk_buff *skb = *pskb;
+ const unsigned char *dest = skb->mac.ethernet->h_dest;
- rcu_read_lock();
- p = skb->dev->br_port;
- if (p == NULL || p->state == BR_STATE_DISABLED)
+ if (p->state == BR_STATE_DISABLED)
goto err;
if (skb->mac.ethernet->h_source[0] & 1)
@@ -128,15 +118,16 @@
if (!dest[5]) {
NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_IN, skb, skb->dev,
NULL, br_stp_handle_bpdu);
- rcu_read_unlock();
- return 0;
+ return 1;
}
}
else if (p->state == BR_STATE_FORWARDING) {
- if (br_should_route_hook && br_should_route_hook(&skb)) {
- rcu_read_unlock();
- return -1;
+ if (br_should_route_hook) {
+ if (br_should_route_hook(pskb))
+ return 0;
+ skb = *pskb;
+ dest = skb->mac.ethernet->h_dest;
}
if (!memcmp(p->br->dev->dev_addr, dest, ETH_ALEN))
@@ -144,12 +135,10 @@
NF_HOOK(PF_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
br_handle_frame_finish);
- rcu_read_unlock();
- return 0;
+ return 1;
}
err:
- rcu_read_unlock();
kfree_skb(skb);
- return 0;
+ return 1;
}
diff -Nru a/net/bridge/br_private.h b/net/bridge/br_private.h
--- a/net/bridge/br_private.h 2004-08-25 14:10:43 -07:00
+++ b/net/bridge/br_private.h 2004-08-25 14:10:43 -07:00
@@ -177,7 +177,7 @@
/* br_input.c */
extern int br_handle_frame_finish(struct sk_buff *skb);
-extern int br_handle_frame(struct sk_buff *skb);
+extern int br_handle_frame(struct net_bridge_port *p, struct sk_buff **pskb);
/* br_ioctl.c */
extern int br_dev_ioctl(struct net_device *dev, struct ifreq *rq, int cmd);
diff -Nru a/net/core/dev.c b/net/core/dev.c
--- a/net/core/dev.c 2004-08-25 14:10:43 -07:00
+++ b/net/core/dev.c 2004-08-25 14:10:43 -07:00
@@ -1682,37 +1682,28 @@
return pt_prev->func(skb, skb->dev, pt_prev);
}
-
#if defined(CONFIG_BRIDGE) || defined (CONFIG_BRIDGE_MODULE)
-int (*br_handle_frame_hook)(struct sk_buff *skb);
+int (*br_handle_frame_hook)(struct net_bridge_port *p, struct sk_buff **pskb);
-static __inline__ int handle_bridge(struct sk_buff *skb,
- struct packet_type *pt_prev)
+static __inline__ int handle_bridge(struct sk_buff **pskb,
+ struct packet_type **pt_prev, int *ret)
{
- int ret = NET_RX_DROP;
- if (pt_prev)
- ret = deliver_skb(skb, pt_prev);
+ struct net_bridge_port *port;
- return ret;
-}
-
-#endif
-
-static inline int __handle_bridge(struct sk_buff *skb,
- struct packet_type **pt_prev, int *ret)
-{
-#if defined(CONFIG_BRIDGE) || defined(CONFIG_BRIDGE_MODULE)
- if (skb->dev->br_port && skb->pkt_type != PACKET_LOOPBACK) {
- *ret = handle_bridge(skb, *pt_prev);
- if (br_handle_frame_hook(skb) == 0)
- return 1;
+ if ((*pskb)->pkt_type == PACKET_LOOPBACK ||
+ (port = rcu_dereference((*pskb)->dev->br_port)) == NULL)
+ return 0;
+ if (*pt_prev) {
+ *ret = deliver_skb(*pskb, *pt_prev);
*pt_prev = NULL;
- }
-#endif
- return 0;
+ }
+
+ return br_handle_frame_hook(port, pskb);
}
-
+#else
+#define handle_bridge(skb, pt_prev, ret) (0)
+#endif
#ifdef CONFIG_NET_CLS_ACT
/* TODO: Maybe we should just force sch_ingress to be compiled in
@@ -1817,7 +1808,7 @@
handle_diverter(skb);
- if (__handle_bridge(skb, &pt_prev, &ret))
+ if (handle_bridge(&skb, &pt_prev, &ret))
goto out;
type = skb->protocol;
|