From 1a4ba64d16a42c1b31d52b671accd7f9103e2626 Mon Sep 17 00:00:00 2001 From: Pablo Neira Ayuso Date: Tue, 10 Mar 2015 10:27:18 +0100 Subject: [PATCH] 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 Signed-off-by: Pablo Neira Ayuso --- net/bridge/br_device.c | 7 ++++++- net/bridge/br_netfilter.c | 9 +++++++-- net/bridge/br_private.h | 10 +++++----- 3 files changed, 18 insertions(+), 8 deletions(-) diff --git a/net/bridge/br_device.c b/net/bridge/br_device.c index 294cbcc49263..4ff77a16956c 100644 --- a/net/bridge/br_device.c +++ b/net/bridge/br_device.c @@ -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; } diff --git a/net/bridge/br_netfilter.c b/net/bridge/br_netfilter.c index a8361c7cdf81..b260a97275db 100644 --- a/net/bridge/br_netfilter.c +++ b/net/bridge/br_netfilter.c @@ -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); diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h index f0a0438dbd6d..b46fa0c5b8ec 100644 --- a/net/bridge/br_private.h +++ b/net/bridge/br_private.h @@ -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) -- 2.20.1