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netfilter: bridge: use rcu hook to resolve br_netfilter dependency 

e5de75b ("netfilter: bridge: move DNAT helper to br_netfilter") results
in the following link problem:

net/bridge/br_device.c:29: undefined reference to `br_nf_prerouting_finish_bridge`

Moreover it creates a hard dependency between br_netfilter and the
bridge core, which is what we've been trying to avoid so far.

Resolve this problem by using a hook structure so we reduce #ifdef
pollution and keep bridge netfilter specific code under br_netfilter.c
which was the original intention.

Reported-by: Simon Horman <simon.horman@netronome.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Pablo Neira Ayuso 2015-03-10 10:27:18 +01:00
parent a03a8dbe20
commit 1a4ba64d16
3 changed files with 18 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
net/bridge/br_device.c
View File

@ -25,6 +25,9 @@
#define COMMON_FEATURES (NETIF_F_SG | NETIF_F_FRAGLIST | NETIF_F_HIGHDMA | \
NETIF_F_GSO_MASK | NETIF_F_HW_CSUM)
const struct nf_br_ops __rcu *nf_br_ops __read_mostly;
EXPORT_SYMBOL_GPL(nf_br_ops);
/* net device transmit always called with BH disabled */
netdev_tx_t br_dev_xmit(struct sk_buff *skb, struct net_device *dev)
{
@ -33,10 +36,12 @@ netdev_tx_t br_dev_xmit(struct sk_buff *skb, struct net_device *dev)
struct net_bridge_fdb_entry *dst;
struct net_bridge_mdb_entry *mdst;
struct pcpu_sw_netstats *brstats = this_cpu_ptr(br->stats);
const struct nf_br_ops *nf_ops;
u16 vid = 0;
rcu_read_lock();
if (br_nf_prerouting_finish_bridge(skb)) {
nf_ops = rcu_dereference(nf_br_ops);
if (nf_ops && nf_ops->br_dev_xmit_hook(skb)) {
rcu_read_unlock();
return NETDEV_TX_OK;
}

9
net/bridge/br_netfilter.c
View File

@ -914,7 +914,7 @@ static void br_nf_pre_routing_finish_bridge_slow(struct sk_buff *skb)
br_handle_frame_finish(skb);
}
int br_nf_prerouting_finish_bridge(struct sk_buff *skb)
static int br_nf_dev_xmit(struct sk_buff *skb)
{
if (skb->nf_bridge && (skb->nf_bridge->mask & BRNF_BRIDGED_DNAT)) {
br_nf_pre_routing_finish_bridge_slow(skb);
@ -922,7 +922,10 @@ int br_nf_prerouting_finish_bridge(struct sk_buff *skb)
}
return 0;
}
EXPORT_SYMBOL_GPL(br_nf_prerouting_finish_bridge);
static const struct nf_br_ops br_ops = {
.br_dev_xmit_hook = br_nf_dev_xmit,
};
void br_netfilter_enable(void)
{
@ -1061,12 +1064,14 @@ static int __init br_netfilter_init(void)
return -ENOMEM;
}
#endif
RCU_INIT_POINTER(nf_br_ops, &br_ops);
printk(KERN_NOTICE "Bridge firewalling registered\n");
return 0;
}
static void __exit br_netfilter_fini(void)
{
RCU_INIT_POINTER(nf_br_ops, NULL);
nf_unregister_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
#ifdef CONFIG_SYSCTL
unregister_net_sysctl_table(brnf_sysctl_header);

10
net/bridge/br_private.h
View File

@ -763,17 +763,17 @@ static inline int br_vlan_enabled(struct net_bridge *br)
}
#endif
struct nf_br_ops {
int (*br_dev_xmit_hook)(struct sk_buff *skb);
};
extern const struct nf_br_ops __rcu *nf_br_ops;
/* br_netfilter.c */
#if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
int br_nf_prerouting_finish_bridge(struct sk_buff *skb);
int br_nf_core_init(void);
void br_nf_core_fini(void);
void br_netfilter_rtable_init(struct net_bridge *);
#else
static inline int br_nf_prerouting_finish_bridge(struct sk_buff *skb)
{
return 0;
}
static inline int br_nf_core_init(void) { return 0; }
static inline void br_nf_core_fini(void) {}
#define br_netfilter_rtable_init(x)