[PATCH net-next] xfrm: policy: Remove obsolete WARN while xfrm policy inserting

[PATCH net-next] xfrm: policy: Remove obsolete WARN while xfrm policy inserting

[YueHaibing]

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.

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
---
 net/xfrm/xfrm_policy.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index dbda08e..5c4387c 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -1508,7 +1508,7 @@ static void xfrm_policy_insert_inexact_list(struct hlist_head *chain,
 		    !selector_cmp(&pol->selector, &policy->selector) &&
 		    xfrm_policy_mark_match(policy, pol) &&
 		    xfrm_sec_ctx_match(pol->security, policy->security) &&
-		    !WARN_ON(delpol)) {
+		    !delpol) {
 			delpol = pol;
 			if (policy->priority > pol->priority)
 				continue;
@@ -1543,7 +1543,7 @@ static struct xfrm_policy *xfrm_policy_insert_list(struct hlist_head *chain,
 		    !selector_cmp(&pol->selector, &policy->selector) &&
 		    xfrm_policy_mark_match(policy, pol) &&
 		    xfrm_sec_ctx_match(pol->security, policy->security) &&
-		    !WARN_ON(delpol)) {
+		    !delpol) {
 			if (excl)
 				return ERR_PTR(-EEXIST);
 			delpol = pol;
-- 
1.8.3.1

Re: [PATCH net-next] xfrm: policy: Remove obsolete WARN while xfrm policy inserting

[Steffen Klassert]

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?

Thanks!

Re: [PATCH net-next] xfrm: policy: Remove obsolete WARN while xfrm policy inserting

[Yuehaibing]

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
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.

> 
> Thanks!
> 
> 

Re: [PATCH net-next] xfrm: policy: Remove obsolete WARN while xfrm policy inserting

[Steffen Klassert]

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?

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.

> 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.

Re: [PATCH net-next] xfrm: policy: Remove obsolete WARN while xfrm policy inserting

[Yuehaibing]

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.
> 
> 
> .
> 

Re: [PATCH net-next] xfrm: policy: Remove obsolete WARN while xfrm policy inserting

[Steffen Klassert]

On Thu, Apr 09, 2020 at 04:19:37PM +0800, Yuehaibing wrote:
> 
> 
> 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？

Yes, xfrm_policy_mark_match should only replace if the found
policy has the same lookup keys.

Re: [PATCH net-next] xfrm: policy: Remove obsolete WARN while xfrm policy inserting

[Yuehaibing]

On 2020/4/15 15:14, Steffen Klassert wrote:
> On Thu, Apr 09, 2020 at 04:19:37PM +0800, Yuehaibing wrote:
>>
>>
>> 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？
> 
> Yes, xfrm_policy_mark_match should only replace if the found
> policy has the same lookup keys.

I'm wonder that lookup keys means association of mark.v and mark.m, or the mark (mark.v & mark.m).

In above my case, policy B and C has the same mark (that is 0), if the lookup keys is mark, replacement is permitted.

If lookup keys is association of mark.v and mark.m, then:

policy E (mark.v = 0x1, mark.m = 0x3, priority = 1)
policy F (mark.v = 0x1, mark.m = 0x5, priority = 1)

E should not be replaced by F, but this is permitted now.

> 
> .
> 

Re: [PATCH net-next] xfrm: policy: Remove obsolete WARN while xfrm policy inserting

[Steffen Klassert]

On Fri, Apr 17, 2020 at 07:01:52PM +0800, Yuehaibing wrote:
> On 2020/4/15 15:14, Steffen Klassert wrote:
> > On Thu, Apr 09, 2020 at 04:19:37PM +0800, Yuehaibing wrote:
> >>
> >>
> >> 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？
> > 
> > Yes, xfrm_policy_mark_match should only replace if the found
> > policy has the same lookup keys.
> 
> I'm wonder that lookup keys means association of mark.v and mark.m, or the mark (mark.v & mark.m).

Good point. I'd say the lookup lookup keys are identical if the policy
lookup can't distinguish between the policies. So (mark.v & mark.m)
should be it.