From: Florian Westphal <fw@xxxxxxxxx>
This moves bridge hooks to a register-when-needed scheme.
We use a device notifier to register the 'call-iptables' netfilter hooks
only once a bridge gets added.
This means that if the initial namespace uses a bridge, newly created
network namespaces no longer get the PRE_ROUTING ipt_sabotage hook.
It will registered in that network namespace once a bridge is created
within that namespace.
A few modules still use global hooks:
- conntrack
- bridge PF_BRIDGE hooks
- IPVS
- CLUSTER match (deprecated)
- SYNPROXY
As long as these modules are not loaded/used, a new network namespace has
empty hook list and NF_HOOK() will boil down to single list_empty test even
if initial namespace does stateless packet filtering.
Signed-off-by: Florian Westphal <fw@xxxxxxxxx>
Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
---
net/bridge/br_netfilter_hooks.c | 68 +++++++++++++++++++++++++++++++++++++++--
1 file changed, 65 insertions(+), 3 deletions(-)
diff --git a/net/bridge/br_netfilter_hooks.c b/net/bridge/br_netfilter_hooks.c
index 7ddbe7e..44114a9 100644
--- a/net/bridge/br_netfilter_hooks.c
+++ b/net/bridge/br_netfilter_hooks.c
@@ -37,6 +37,7 @@
#include <net/addrconf.h>
#include <net/route.h>
#include <net/netfilter/br_netfilter.h>
+#include <net/netns/generic.h>
#include <asm/uaccess.h>
#include "br_private.h"
@@ -44,6 +45,12 @@
#include <linux/sysctl.h>
#endif
+static int brnf_net_id __read_mostly;
+
+struct brnf_net {
+ bool enabled;
+};
+
#ifdef CONFIG_SYSCTL
static struct ctl_table_header *brnf_sysctl_header;
static int brnf_call_iptables __read_mostly = 1;
@@ -938,6 +945,53 @@ static struct nf_hook_ops br_nf_ops[] __read_mostly = {
},
};
+static int brnf_device_event(struct notifier_block *unused, unsigned long event,
+ void *ptr)
+{
+ struct net_device *dev = netdev_notifier_info_to_dev(ptr);
+ struct brnf_net *brnet;
+ struct net *net;
+ int ret;
+
+ if (event != NETDEV_REGISTER || !(dev->priv_flags & IFF_EBRIDGE))
+ return NOTIFY_DONE;
+
+ ASSERT_RTNL();
+
+ net = dev_net(dev);
+ brnet = net_generic(net, brnf_net_id);
+ if (brnet->enabled)
+ return NOTIFY_OK;
+
+ ret = nf_register_net_hooks(net, br_nf_ops, ARRAY_SIZE(br_nf_ops));
+ if (ret)
+ return NOTIFY_BAD;
+
+ brnet->enabled = true;
+ return NOTIFY_OK;
+}
+
+static void __net_exit brnf_exit_net(struct net *net)
+{
+ struct brnf_net *brnet = net_generic(net, brnf_net_id);
+
+ if (!brnet->enabled)
+ return;
+
+ nf_unregister_net_hooks(net, br_nf_ops, ARRAY_SIZE(br_nf_ops));
+ brnet->enabled = false;
+}
+
+static struct pernet_operations brnf_net_ops __read_mostly = {
+ .exit = brnf_exit_net,
+ .id = &brnf_net_id,
+ .size = sizeof(struct brnf_net),
+};
+
+static struct notifier_block brnf_notifier __read_mostly = {
+ .notifier_call = brnf_device_event,
+};
+
#ifdef CONFIG_SYSCTL
static
int brnf_sysctl_call_tables(struct ctl_table *ctl, int write,
@@ -1003,16 +1057,23 @@ static int __init br_netfilter_init(void)
{
int ret;
- ret = nf_register_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
+ ret = register_pernet_subsys(&brnf_net_ops);
if (ret < 0)
return ret;
+ ret = register_netdevice_notifier(&brnf_notifier);
+ if (ret < 0) {
+ unregister_pernet_subsys(&brnf_net_ops);
+ return ret;
+ }
+
#ifdef CONFIG_SYSCTL
brnf_sysctl_header = register_net_sysctl(&init_net, "net/bridge", brnf_table);
if (brnf_sysctl_header == NULL) {
printk(KERN_WARNING
"br_netfilter: can't register to sysctl.\n");
- nf_unregister_hooks(br_nf_ops, ARRAY_SIZE(br_nf_ops));
+ unregister_netdevice_notifier(&brnf_notifier);
+ unregister_pernet_subsys(&brnf_net_ops);
return -ENOMEM;
}
#endif
@@ -1024,7 +1085,8 @@ static int __init br_netfilter_init(void)
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));
+ unregister_netdevice_notifier(&brnf_notifier);
+ unregister_pernet_subsys(&brnf_net_ops);
#ifdef CONFIG_SYSCTL
unregister_net_sysctl_table(brnf_sysctl_header);
#endif
--
2.1.4
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