From 6c5d5cfbe3c59429e6d6f66477a7609aacf69751 Mon Sep 17 00:00:00 2001 From: Xin Long Date: Tue, 20 Dec 2016 19:14:34 +0800 Subject: netfilter: ipt_CLUSTERIP: check duplicate config when initializing 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 and correct the return err. 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 Signed-off-by: Xin Long Signed-off-by: Pablo Neira Ayuso --- net/ipv4/netfilter/ipt_CLUSTERIP.c | 34 +++++++++++++++++++++++----------- 1 file changed, 23 insertions(+), 11 deletions(-) diff --git a/net/ipv4/netfilter/ipt_CLUSTERIP.c b/net/ipv4/netfilter/ipt_CLUSTERIP.c index 21db00d0362b..a6b8c1a4102b 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); @@ -166,14 +166,15 @@ 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) - return NULL; + return ERR_PTR(-ENOMEM); c->dev = dev; c->clusterip = ip; @@ -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 ERR_PTR(-EBUSY); + } + + 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; + + return ERR_PTR(-ENOMEM); } } #endif - spin_lock_bh(&cn->lock); - list_add_rcu(&c->list, &cn->configs); - spin_unlock_bh(&cn->lock); - return c; } @@ -410,9 +422,9 @@ static int clusterip_tg_check(const struct xt_tgchk_param *par) config = clusterip_config_init(cipinfo, e->ip.dst.s_addr, dev); - if (!config) { + if (IS_ERR(config)) { dev_put(dev); - return -ENOMEM; + return PTR_ERR(config); } dev_mc_add(config->dev, config->clustermac); } -- cgit v1.2.3