[PATCH net v2] net/sched: cls_flower: fix only mask bit check in the validate_ct_state

[PATCH net v2] net/sched: cls_flower: fix only mask bit check in the validate_ct_state

[wenxu]

From: wenxu <wenxu@ucloud.cn>

The ct_state validate should not only check the mask bit and also
check mask_bit & key_bit..
For the +new+est case example, The 'new' and 'est' bits should be
set in both state_mask and state flags. Or the -new-est case also
will be reject by kernel.
When Openvswitch with two flows
ct_state=+trk+new,action=commit,forward
ct_state=+trk+est,action=forward

A packet go through the kernel  and the contrack state is invalid,
The ct_state will be +trk-inv. Upcall to the ovs-vswitchd, the
finally dp action will be drop with -new-est+trk.

Fixes: 1bcc51ac0731 ("net/sched: cls_flower: Reject invalid ct_state flags rules")
Fixes: 3aed8b63336c ("net/sched: cls_flower: validate ct_state for invalid and reply flags")
Signed-off-by: wenxu <wenxu@ucloud.cn>
---
 net/sched/cls_flower.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/sched/cls_flower.c b/net/sched/cls_flower.c
index d097b5c..c69a4ba 100644
--- a/net/sched/cls_flower.c
+++ b/net/sched/cls_flower.c
@@ -1451,7 +1451,7 @@ static int fl_set_key_ct(struct nlattr **tb,
 			       &mask->ct_state, TCA_FLOWER_KEY_CT_STATE_MASK,
 			       sizeof(key->ct_state));
 
-		err = fl_validate_ct_state(mask->ct_state,
+		err = fl_validate_ct_state(key->ct_state & mask->ct_state,
 					   tb[TCA_FLOWER_KEY_CT_STATE_MASK],
 					   extack);
 		if (err)
-- 
1.8.3.1

Re: [PATCH net v2] net/sched: cls_flower: fix only mask bit check in the validate_ct_state

[Marcelo Ricardo Leitner]

On Wed, Mar 17, 2021 at 12:02:43PM +0800, wenxu@ucloud.cn wrote:
> From: wenxu <wenxu@ucloud.cn>
> 
> The ct_state validate should not only check the mask bit and also
> check mask_bit & key_bit..
> For the +new+est case example, The 'new' and 'est' bits should be
> set in both state_mask and state flags. Or the -new-est case also
> will be reject by kernel.
> When Openvswitch with two flows
> ct_state=+trk+new,action=commit,forward
> ct_state=+trk+est,action=forward
> 
> A packet go through the kernel  and the contrack state is invalid,
> The ct_state will be +trk-inv. Upcall to the ovs-vswitchd, the
> finally dp action will be drop with -new-est+trk.
> 
> Fixes: 1bcc51ac0731 ("net/sched: cls_flower: Reject invalid ct_state flags rules")
> Fixes: 3aed8b63336c ("net/sched: cls_flower: validate ct_state for invalid and reply flags")
> Signed-off-by: wenxu <wenxu@ucloud.cn>
> ---
>  net/sched/cls_flower.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/sched/cls_flower.c b/net/sched/cls_flower.c
> index d097b5c..c69a4ba 100644
> --- a/net/sched/cls_flower.c
> +++ b/net/sched/cls_flower.c
> @@ -1451,7 +1451,7 @@ static int fl_set_key_ct(struct nlattr **tb,
>  			       &mask->ct_state, TCA_FLOWER_KEY_CT_STATE_MASK,
>  			       sizeof(key->ct_state));
>  
> -		err = fl_validate_ct_state(mask->ct_state,
> +		err = fl_validate_ct_state(key->ct_state & mask->ct_state,

Or that, yes. The thing I was wondering on this is if it would be a
problem to have something like
key = trk,inv
mask = trk,new,est,inv
because in essence, this is +trk+inv-new-est, and it's worrying about
bits that shouldn't be considered if +inv is there.
I don't see a reason for it to be that restrictive, though, and it
will work as expected.

Reviewed-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>

>  					   tb[TCA_FLOWER_KEY_CT_STATE_MASK],
>  					   extack);
>  		if (err)
> -- 
> 1.8.3.1
> 

Re: [PATCH net v2] net/sched: cls_flower: fix only mask bit check in the validate_ct_state

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (refs/heads/master):

On Wed, 17 Mar 2021 12:02:43 +0800 you wrote:
> From: wenxu <wenxu@ucloud.cn>
> 
> The ct_state validate should not only check the mask bit and also
> check mask_bit & key_bit..
> For the +new+est case example, The 'new' and 'est' bits should be
> set in both state_mask and state flags. Or the -new-est case also
> will be reject by kernel.
> When Openvswitch with two flows
> ct_state=+trk+new,action=commit,forward
> ct_state=+trk+est,action=forward
> 
> [...]

Here is the summary with links:
  - [net,v2] net/sched: cls_flower: fix only mask bit check in the validate_ct_state
    https://git.kernel.org/netdev/net/c/afa536d8405a

You are awesome, thank you!
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