Subject: Re: [PATCH 01/13] netfilter: fix problem with proto register

From: Gao feng <[email-masked]>
Date: Tue, 26 Jun 2012 11:40:14 +0800

Hi Pablo:

于 2012年06月25日 19:12, Pablo Neira Ayuso 写道:
> On Thu, Jun 21, 2012 at 10:36:38PM +0800, Gao feng wrote:
>> before commit 2c352f444ccfa966a1aa4fd8e9ee29381c467448
>> (netfilter: nf_conntrack: prepare namespace support for
>> l4 protocol trackers), we register sysctl before register
>> protos, so if sysctl is registered faild, the protos will
>> not be registered.
>>
>> but now, we register protos first, and when register
>> sysctl failed, we can use protos too, it's different
>> from before.
> 
> No, this has to be an all-or-nothing game. If one fails, everything
> else that you've registered has to be unregistered.

indeed,this is an all-or-nothing game right now,please look at the ipv4_net_init,
when we register nf_conntrack_l3proto_ipv4 failed,we will unregister the already
registered l4protoes, and in nf_conntrack_l4proto_unregister,we will call
nf_ct_l4proto_unregister_sysctl to free the sysctl table.

> 
>> so change to register sysctl before register protos.
>>
>> Signed-off-by: Gao feng <[email-masked]>
>> ---
>>  net/netfilter/nf_conntrack_proto.c |   36 +++++++++++++++++++++++-------------
>>  1 files changed, 23 insertions(+), 13 deletions(-)
>>
>> diff --git a/net/netfilter/nf_conntrack_proto.c b/net/netfilter/nf_conntrack_proto.c
>> index 1ea9194..9bd88aa 100644
>> --- a/net/netfilter/nf_conntrack_proto.c
>> +++ b/net/netfilter/nf_conntrack_proto.c
>> @@ -253,18 +253,23 @@ int nf_conntrack_l3proto_register(struct net *net,
>>  {
>>  	int ret = 0;
>>  
>> -	if (net == &init_net)
>> -		ret = nf_conntrack_l3proto_register_net(proto);
>> +	if (proto->init_net) {
>> +		ret = proto->init_net(net);
>> +		if (ret < 0)
>> +			return ret;
>> +	}
>>  
>> +	ret = nf_ct_l3proto_register_sysctl(net, proto);
>>  	if (ret < 0)
>>  		return ret;
> 
> This is still wrong.
> 
> If nf_ct_l3proto_register_sysctl fails, we'll leak the memory that has
> been reserved by proto->init_net.
> 

we have freed the memory in nf_ct_l[3,4]proto_register_sysctl when we
call nf_ct_register_sysctl failed, so there is no need to free this memory
in nf_conntrack_l[3,4]proto_register.

>> -	if (proto->init_net) {
>> -		ret = proto->init_net(net);
>> +	if (net == &init_net) {
>> +		ret = nf_conntrack_l3proto_register_net(proto);
>>  		if (ret < 0)
>> -			return ret;
>> +			nf_ct_l3proto_unregister_sysctl(net, proto);
>>  	}
>> -	return nf_ct_l3proto_register_sysctl(net, proto);
>> +
>> +	return ret;
>>  }
>>  EXPORT_SYMBOL_GPL(nf_conntrack_l3proto_register);
>>  
>> @@ -454,19 +459,24 @@ int nf_conntrack_l4proto_register(struct net *net,
>>  				  struct nf_conntrack_l4proto *l4proto)
>>  {
>>  	int ret = 0;
>> -	if (net == &init_net)
>> -		ret = nf_conntrack_l4proto_register_net(l4proto);
>>  
>> -	if (ret < 0)
>> -		return ret;
>> -
>> -	if (l4proto->init_net)
>> +	if (l4proto->init_net) {
>>  		ret = l4proto->init_net(net);
>> +		if (ret < 0)
>> +			return ret;
>> +	}
>>  
>> +	ret = nf_ct_l4proto_register_sysctl(net, l4proto);
>>  	if (ret < 0)
>>  		return ret;
>>  
>> -	return nf_ct_l4proto_register_sysctl(net, l4proto);
>> +	if (net == &init_net) {
>> +		ret = nf_conntrack_l4proto_register_net(l4proto);
>> +		if (ret < 0)
>> +			nf_ct_l4proto_unregister_sysctl(net, l4proto);
>> +	}
>> +
>> +	return ret;
>>  }
>>  EXPORT_SYMBOL_GPL(nf_conntrack_l4proto_register);
>>  
>> -- 
>> 1.7.7.6
>>
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