Subject: Re: [PATCH 01/17] netfilter: add struct nf_proto_net for register l4proto sysctl

From: Gao feng <[email-masked]>
Date: Thu, 24 May 2012 09:35:50 +0800

Hi pablo:

于 2012年05月23日 18:12, Pablo Neira Ayuso 写道:
> On Mon, May 14, 2012 at 04:52:11PM +0800, Gao feng wrote:
>> From: Gao feng <[email-masked]>
>>
>> the struct nf_proto_net stroes proto's ctl_table_header and ctl_table,
>> nf_ct_l4proto_(un)register_sysctl use it to register sysctl.
>>
>> there are some changes for struct nf_conntrack_l4proto:
>> - add field compat to identify if this proto should do compat.
>> - the net_id field is used to store the pernet_operations id
>>   that belones to l4proto.
>> - init_net will be used to initial the proto's pernet data
>>
>> and add init_net for struct nf_conntrack_l3proto too.
> 
> This patchset looks bette but there are still things that we have to
> resolve.
> 
> The first one (regarding this patch 1/17) changes in:
> * include/net/netfilter/nf_conntrack_l4proto.h
> * include/net/netns/conntrack.h
> 
> should be included in:
> [PATCH] netfilter: add namespace support for l4proto
> 
> And changes in:
> * include/net/netfilter/nf_conntrack_l3proto.h
> 
> should be included in:
> [PATCH] netfilter: add namespace support for l3proto
> 
> I already told you. A patch that adds a structure without using it,
> is not good. The structure has to go together with the code uses it.
> 

It seams this patch should be merged to "netfilter: add namespace support for l4proto"
the struct nf_proto_net is first used there.

> More comments below.
> 
>> Acked-by: Eric W. Biederman <[email-masked]>
>> Signed-off-by: Gao feng <[email-masked]>
>> ---
>>  include/net/netfilter/nf_conntrack_l3proto.h |    3 +++
>>  include/net/netfilter/nf_conntrack_l4proto.h |    6 ++++++
>>  include/net/netns/conntrack.h                |   12 ++++++++++++
>>  3 files changed, 21 insertions(+), 0 deletions(-)
>>
>> diff --git a/include/net/netfilter/nf_conntrack_l3proto.h b/include/net/netfilter/nf_conntrack_l3proto.h
>> index 9699c02..9766005 100644
>> --- a/include/net/netfilter/nf_conntrack_l3proto.h
>> +++ b/include/net/netfilter/nf_conntrack_l3proto.h
>> @@ -69,6 +69,9 @@ struct nf_conntrack_l3proto {
>>  	struct ctl_table	*ctl_table;
>>  #endif /* CONFIG_SYSCTL */
>>  
>> +	/* Init l3proto pernet data */
>> +	int (*init_net)(struct net *net);
>> +
>>  	/* Module (if any) which this is connected to. */
>>  	struct module *me;
>>  };
>> diff --git a/include/net/netfilter/nf_conntrack_l4proto.h b/include/net/netfilter/nf_conntrack_l4proto.h
>> index 3b572bb..a90eab5 100644
>> --- a/include/net/netfilter/nf_conntrack_l4proto.h
>> +++ b/include/net/netfilter/nf_conntrack_l4proto.h
>> @@ -22,6 +22,8 @@ struct nf_conntrack_l4proto {
>>  	/* L4 Protocol number. */
>>  	u_int8_t l4proto;
>>  
>> +	u_int8_t compat;
> 
> I don't see why we need this new field.
> 
> It seems to be set to 1 in each structure that has set:
> 
> .ctl_compat_table
> 
> to non-NULL. So, it's redundant.
> 
> Moreover, you already know from the protocol tracker itself if you
> have to allocate the compat ctl table or not.
> 
> In other words: You set compat to 1 for nf_conntrack_l4proto_generic.
> Then, you pass that compat value to generic_init_net via ->inet_net
> again, but this information (that determines if the compat has to be
> done or not) is already in the scope of the protocol tracker.
> 

because some protocols such l4proto_tcp6 and l4proto_tcp use the same init_net
function. the l4proto_tcp6 doesn't need compat sysctl, so we should use this new
field to identify if we should kmemdup compat_sysctl_table.

and beacuse protocols will have pernet ctl_compat_table and ctl_table,the .ctl_compat_table
field will be deleted in patch 15/17. so we should the new field compat.

actually, we don't need to pass compat value for generic_init_net,beacuse
we know l4proto_generic need compat. But consider there are l4proto_tcp(6), and in order to keep
code readable,I prefer to add compat field and pass it to init_net.

> You have to fix this.
> 
>> +
>>  	/* Try to fill in the third arg: dataoff is offset past network protocol
>>             hdr.  Return true if possible. */
>>  	bool (*pkt_to_tuple)(const struct sk_buff *skb, unsigned int dataoff,
>> @@ -103,6 +105,10 @@ struct nf_conntrack_l4proto {
>>  	struct ctl_table	*ctl_compat_table;
>>  #endif
>>  #endif
>> +	int	*net_id;
>> +	/* Init l4proto pernet data */
>> +	int (*init_net)(struct net *net, u_int8_t compat);
>> +
>>  	/* Protocol name */
>>  	const char *name;
>>  
>> diff --git a/include/net/netns/conntrack.h b/include/net/netns/conntrack.h
>> index a053a19..1f53038 100644
>> --- a/include/net/netns/conntrack.h
>> +++ b/include/net/netns/conntrack.h
>> @@ -8,6 +8,18 @@
>>  struct ctl_table_header;
>>  struct nf_conntrack_ecache;
>>  
>> +struct nf_proto_net {
>> +#ifdef CONFIG_SYSCTL
>> +	struct ctl_table_header *ctl_table_header;
>> +	struct ctl_table        *ctl_table;
>> +#ifdef CONFIG_NF_CONNTRACK_PROC_COMPAT
>> +	struct ctl_table_header *ctl_compat_header;
>> +	struct ctl_table        *ctl_compat_table;
>> +#endif
>> +#endif
>> +	unsigned int		users;
>> +};
>> +
>>  struct netns_ct {
>>  	atomic_t		count;
>>  	unsigned int		expect_count;
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