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SubjectRe: [PATCH v2] xfrm: policy: Fix xfrm policy match
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On 2020/5/22 13:49, Xin Long wrote:
> On Fri, May 22, 2020 at 9:45 AM Yuehaibing <yuehaibing@huawei.com> wrote:
>>
>> On 2020/5/21 14:49, Xin Long wrote:
>>> On Tue, May 19, 2020 at 4:53 PM Steffen Klassert
>>> <steffen.klassert@secunet.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)
> I'd think these are 2 different policies.
>
>>
>> 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.
> Yes, this may happen when a user adds 2 policies like that.
> But I think this's a problem that the user doesn't configure it well,
> 'priority' should be set.
> and this can not be avoided, also such as:
>
> policy A (mark.v = 0xff00, mark.m = 0x1000, priority = 1)
> policy B (mark.v = 0x00ff, mark.m = 0x0011, priority = 1)
>
> try with 0x12341011
>
> So just be it, let users decide.

Ok, this make sense.

>
> .
>

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