From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marcelo Ricardo Leitner Subject: Re: [PATCH net] netfilter: check duplicate config when initializing in ipt_CLUSTERIP Date: Sun, 18 Dec 2016 23:02:32 -0200 Message-ID: <20161219010232.GA31360@localhost.localdomain> References: <9b3e1f76b5670d33727e63b6e166ae416b0d65af.1481776300.git.lucien.xin@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: network dev , netfilter-devel@vger.kernel.org, davem@davemloft.net To: Xin Long Return-path: Received: from mx1.redhat.com ([209.132.183.28]:39874 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752034AbcLSBCg (ORCPT ); Sun, 18 Dec 2016 20:02:36 -0500 Content-Disposition: inline In-Reply-To: <9b3e1f76b5670d33727e63b6e166ae416b0d65af.1481776300.git.lucien.xin@gmail.com> Sender: netfilter-devel-owner@vger.kernel.org List-ID: On Thu, Dec 15, 2016 at 12:31:40PM +0800, Xin Long wrote: > 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 > Signed-off-by: Xin Long Reviewed-by: Marcelo Ricardo Leitner > --- > 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@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >