netdev - Re: [PATCH] net/sched: act_ct: add nat mangle action only for NAT-conntrack

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Message-ID: <09b6cd0b-5477-0e84-2a95-12eee55845d0@ucloud.cn>
Date:   Sat, 30 May 2020 08:04:07 +0800
From:   wenxu <wenxu@...oud.cn>
To:     Marcelo Ricardo Leitner <marcelo.leitner@...il.com>
Cc:     paulb@...lanox.com, netdev@...r.kernel.org, davem@...emloft.net
Subject: Re: [PATCH] net/sched: act_ct: add nat mangle action only for
 NAT-conntrack


在 2020/5/30 1:56, Marcelo Ricardo Leitner 写道:
> On Fri, May 29, 2020 at 12:07:45PM +0800, wenxu@...oud.cn wrote:
>> From: wenxu <wenxu@...oud.cn>
>>
>> Currently add nat mangle action with comparing invert and ori tuple.
>> It is better to check IPS_NAT_MASK flags first to avoid non necessary
>> memcmp for non-NAT conntrack.
>>
>> Signed-off-by: wenxu <wenxu@...oud.cn>
>> ---
>>  net/sched/act_ct.c | 19 +++++++++++++------
>>  1 file changed, 13 insertions(+), 6 deletions(-)
>>
>> diff --git a/net/sched/act_ct.c b/net/sched/act_ct.c
>> index c50a86a..d621152 100644
>> --- a/net/sched/act_ct.c
>> +++ b/net/sched/act_ct.c
>> @@ -198,18 +198,21 @@ static int tcf_ct_flow_table_add_action_nat(struct net *net,
>>  					    struct flow_action *action)
>>  {
>>  	const struct nf_conntrack_tuple *tuple = &ct->tuplehash[dir].tuple;
>> +	bool nat = ct->status & IPS_NAT_MASK;
>>  	struct nf_conntrack_tuple target;
> [A]
>
>>  
>>  	nf_ct_invert_tuple(&target, &ct->tuplehash[!dir].tuple);
>>  
>>  	switch (tuple->src.l3num) {
>>  	case NFPROTO_IPV4:
>> -		tcf_ct_flow_table_add_action_nat_ipv4(tuple, target,
>> -						      action);
>> +		if (nat)
> Why do the same check multiple times, on all actions? As no other
> action is performed if not doing a nat, seems at [A] above, it could
> just:
>
> if (!nat)
> 	return 0;

This function is not always return 0.  It is the same for non-nat conntrack.

If the ether proto is not ipv4 or ipv6 and the ip_proto is not tcp and udp,

this function should return -EOPNOTSUPP. Check the nat for each type

is just to following the rule.

>
>> +			tcf_ct_flow_table_add_action_nat_ipv4(tuple, target,
>> +							      action);
>>  		break;
>>  	case NFPROTO_IPV6:
>> -		tcf_ct_flow_table_add_action_nat_ipv6(tuple, target,
>> -						      action);
>> +		if (nat)
>> +			tcf_ct_flow_table_add_action_nat_ipv6(tuple, target,
>> +							      action);
>>  		break;
>>  	default:
>>  		return -EOPNOTSUPP;
>> @@ -217,10 +220,14 @@ static int tcf_ct_flow_table_add_action_nat(struct net *net,
>>  
>>  	switch (nf_ct_protonum(ct)) {
>>  	case IPPROTO_TCP:
>> -		tcf_ct_flow_table_add_action_nat_tcp(tuple, target, action);
>> +		if (nat)
>> +			tcf_ct_flow_table_add_action_nat_tcp(tuple, target,
>> +							     action);
>>  		break;
>>  	case IPPROTO_UDP:
>> -		tcf_ct_flow_table_add_action_nat_udp(tuple, target, action);
>> +		if (nat)
>> +			tcf_ct_flow_table_add_action_nat_udp(tuple, target,
>> +							     action);
>>  		break;
>>  	default:
>>  		return -EOPNOTSUPP;
>> -- 
>> 1.8.3.1
>>