Now when adding an ipt_CLUSTERIP rule, it only checks duplicate config in
clusterip_config_find_get(). But after that, there may be still another
thread to insert a config with the same ip, then it leaves proc_create_data
to do duplicate check.
It's more reasonable to check duplicate config by ipt_CLUSTERIP itself,
instead of checking it by proc fs duplicate file check. Before, when proc
fs allowed duplicate name files in a directory, It could even crash kernel
because of use-after-free.
This patch is to check duplicate config under the protection of clusterip
net lock when initializing a new config.
Note that it also moves proc file node creation after adding new config, as
proc_create_data may sleep, it couldn't be called under the clusterip_net
lock. clusterip_config_find_get returns NULL if c->pde is null to make sure
it can't be used until the proc file node creation is done.
Suggested-by: Marcelo Ricardo Leitner <marcelo.leitner@xxxxxxxxx>
Signed-off-by: Xin Long <lucien.xin@xxxxxxxxx>
---
net/ipv4/netfilter/ipt_CLUSTERIP.c | 26 +++++++++++++++++++-------
1 file changed, 19 insertions(+), 7 deletions(-)
diff --git a/net/ipv4/netfilter/ipt_CLUSTERIP.c b/net/ipv4/netfilter/ipt_CLUSTERIP.c
index 21db00d..0e71cac 100644
--- a/net/ipv4/netfilter/ipt_CLUSTERIP.c
+++ b/net/ipv4/netfilter/ipt_CLUSTERIP.c
@@ -144,7 +144,7 @@ clusterip_config_find_get(struct net *net, __be32 clusterip, int entry)
rcu_read_lock_bh();
c = __clusterip_config_find(net, clusterip);
if (c) {
- if (unlikely(!atomic_inc_not_zero(&c->refcount)))
+ if (!c->pde || unlikely(!atomic_inc_not_zero(&c->refcount)))
c = NULL;
else if (entry)
atomic_inc(&c->entries);
@@ -166,10 +166,11 @@ clusterip_config_init_nodelist(struct clusterip_config *c,
static struct clusterip_config *
clusterip_config_init(const struct ipt_clusterip_tgt_info *i, __be32 ip,
- struct net_device *dev)
+ struct net_device *dev)
{
+ struct net *net = dev_net(dev);
struct clusterip_config *c;
- struct clusterip_net *cn = net_generic(dev_net(dev), clusterip_net_id);
+ struct clusterip_net *cn = net_generic(net, clusterip_net_id);
c = kzalloc(sizeof(*c), GFP_ATOMIC);
if (!c)
@@ -185,6 +186,17 @@ clusterip_config_init(const struct ipt_clusterip_tgt_info *i, __be32 ip,
atomic_set(&c->refcount, 1);
atomic_set(&c->entries, 1);
+ spin_lock_bh(&cn->lock);
+ if (__clusterip_config_find(net, ip)) {
+ spin_unlock_bh(&cn->lock);
+ kfree(c);
+
+ return NULL;
+ }
+
+ list_add_rcu(&c->list, &cn->configs);
+ spin_unlock_bh(&cn->lock);
+
#ifdef CONFIG_PROC_FS
{
char buffer[16];
@@ -195,16 +207,16 @@ clusterip_config_init(const struct ipt_clusterip_tgt_info *i, __be32 ip,
cn->procdir,
&clusterip_proc_fops, c);
if (!c->pde) {
+ spin_lock_bh(&cn->lock);
+ list_del_rcu(&c->list);
+ spin_unlock_bh(&cn->lock);
kfree(c);
+
return NULL;
}
}
#endif
- spin_lock_bh(&cn->lock);
- list_add_rcu(&c->list, &cn->configs);
- spin_unlock_bh(&cn->lock);
-
return c;
}
--
2.1.0
--
To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
