netdev - Re: [PATCH v2] xfrm: policy: Fix xfrm policy match

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Date:   Fri, 22 May 2020 09:45:06 +0800
From:   Yuehaibing <yuehaibing@...wei.com>
To:     Xin Long <lucien.xin@...il.com>,
        Steffen Klassert <steffen.klassert@...unet.com>
CC:     Herbert Xu <herbert@...dor.apana.org.au>,
        davem <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>,
        network dev <netdev@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] xfrm: policy: Fix xfrm policy match

On 2020/5/21 14:49, Xin Long wrote:
> On Tue, May 19, 2020 at 4:53 PM Steffen Klassert
> <steffen.klassert@...unet.com> wrote:
>>
>> On Fri, May 15, 2020 at 04:39:57PM +0800, Yuehaibing wrote:
>>>
>>> Friendly ping...
>>>
>>> Any plan for this issue?
>>
>> There was still no consensus between you and Xin on how
>> to fix this issue. Once this happens, I consider applying
>> a fix.
>>
> Sorry, Yuehaibing, I can't really accept to do: (A->mark.m & A->mark.v)
> I'm thinking to change to:
> 
>  static bool xfrm_policy_mark_match(struct xfrm_policy *policy,
>                                    struct xfrm_policy *pol)
>  {
> -       u32 mark = policy->mark.v & policy->mark.m;
> -
> -       if (policy->mark.v == pol->mark.v && policy->mark.m == pol->mark.m)
> -               return true;
> -
> -       if ((mark & pol->mark.m) == pol->mark.v &&
> -           policy->priority == pol->priority)
> +       if (policy->mark.v == pol->mark.v &&
> +           (policy->mark.m == pol->mark.m ||
> +            policy->priority == pol->priority))
>                 return true;
> 
>         return false;
> 
> which means we consider (the same value and mask) or
> (the same value and priority) as the same one. This will
> cover both problems.

  policy A (mark.v = 0x1011, mark.m = 0x1011, priority = 1)
  policy B (mark.v = 0x1001, mark.m = 0x1001, priority = 1)

  when fl->flowi_mark == 0x12341011, in xfrm_policy_match() do check like this:

	(fl->flowi_mark & pol->mark.m) != pol->mark.v

	0x12341011 & 0x1011 == 0x00001011
	0x12341011 & 0x1001 == 0x00001001

 This also match different policy depends on the order of policy inserting.

> 
> .
>