From: Yuehaibing <yuehaibing@huawei.com>
To: Steffen Klassert <steffen.klassert@secunet.com>
Cc: <herbert@gondor.apana.org.au>, <davem@davemloft.net>,
<kuba@kernel.org>, <netdev@vger.kernel.org>,
<linux-kernel@vger.kernel.org>
Subject: Re: [PATCH net-next] xfrm: policy: Remove obsolete WARN while xfrm policy inserting
Date: Thu, 9 Apr 2020 16:19:37 +0800 [thread overview]
Message-ID: <ff4b3d2c-e6b3-33d6-141b-b093db084a18@huawei.com> (raw)
In-Reply-To: <20200406090327.GF13121@gauss3.secunet.de>
On 2020/4/6 17:03, Steffen Klassert wrote:
> On Mon, Mar 30, 2020 at 10:05:32PM +0800, Yuehaibing wrote:
>> On 2020/3/28 19:23, Steffen Klassert wrote:
>>> On Fri, Mar 27, 2020 at 08:34:43PM +0800, YueHaibing wrote:
>>>> Since commit 7cb8a93968e3 ("xfrm: Allow inserting policies with matching
>>>> mark and different priorities"), we allow duplicate policies with
>>>> different priority, this WARN is not needed any more.
>>>
>>> Can you please describe a bit more detailed why this warning
>>> can't trigger anymore?
>>
>> No, this warning is triggered while detect a duplicate entry in the policy list
>>
>> regardless of the priority. If we insert policy like this:
>>
>> policy A (mark.v = 3475289, mark.m = 0, priority = 1) //A is inserted
>> policy B (mark.v = 0, mark.m = 0, priority = 0) //B is inserted
>> policy C (mark.v = 3475289, mark.m = 0, priority = 0) //C is inserted and B is deleted
>
> The codepath that replaces a policy by another should just trigger
> on policy updates (XFRM_MSG_UPDPOLICY). Is that the case in your
> test?
Yes, this is triggered by XFRM_MSG_UPDPOLICY
>
> It should not be possible to add policy C with XFRM_MSG_NEWPOLICY
> as long as you have policy B inserted.
>
> The update replaces an old policy by a new one, the lookup keys of
> the old policy must match the lookup keys of the new one. But policy
> B has not the same lookup keys as C, the mark is different. So B should
> not be replaced with C.
1436 static bool xfrm_policy_mark_match(struct xfrm_policy *policy,
1437 struct xfrm_policy *pol)
1438 {
1439 u32 mark = policy->mark.v & policy->mark.m;
1440
1441 if (policy->mark.v == pol->mark.v && policy->mark.m == pol->mark.m)
1442 return true;
1443
1444 if ((mark & pol->mark.m) == pol->mark.v && //policy is C, pol is B, so mark is 0, pol->mark.m is 0, pol->mark.v is 0
1445 policy->priority == pol->priority) //priority is same zero, so return true, B is replaced with C
1446 return true;
1447
1448 return false;
1449 }
Should xfrm_policy_mark_match be fixed?
>
>> policy D (mark.v = 3475289, mark.m = 0, priority = 1)
>>
>> while finding delpol in xfrm_policy_insert_list,
>> first round delpol is matched C, whose priority is less than D, so contiue the loop,
>> then A is matched, WARN_ON is triggered. It seems the WARN is useless.
>
> Looks like the warning is usefull, it found a bug.
>
>
> .
>
next prev parent reply other threads:[~2020-04-09 8:19 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-27 12:34 [PATCH net-next] xfrm: policy: Remove obsolete WARN while xfrm policy inserting YueHaibing
2020-03-28 11:23 ` Steffen Klassert
2020-03-30 14:05 ` Yuehaibing
2020-04-06 9:03 ` Steffen Klassert
2020-04-09 8:19 ` Yuehaibing [this message]
2020-04-15 7:14 ` Steffen Klassert
2020-04-17 11:01 ` Yuehaibing
2020-04-21 6:28 ` Steffen Klassert
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