Re: Section 4 No. 9,10 Failed was occurred by IPv6 Ready Logo Conformance Test

[Yuki Machida <machida.yuki@jp.fujitsu.com>]

Hi Roy,

On 2016年04月01日 17:00, Yuki Machida wrote:
> Hi Roy,
> 
> Thank you for your advice.
> I am very glad.
> 
> Futher comment below.
> 
> On 2016年04月01日 16:43, Rongqing Li wrote:
>>
>>
>> On 2016年04月01日 15:31, Yuki Machida wrote:
>>> Hi all,
>>>
>>> I tested 4.6-rc1 by IPv6 Ready Logo Core Conformance Test.
>>> 4.6-rc1 has some FAILs in Section 4 (RFC 1981: Path MTU Discovery for IP version 6).
>>> I conformed that it was PASSed in 3.14.28 and it was FAILed in 4.1.17.
>>> I will find a patch between 3.14 and 4.1.
>>>
>>> IPv6 Ready Logo
>>> https://www.ipv6ready.org/
>>> TAHI Project
>>> http://www.tahi.org/
>>>
>>> I ran the IPv6 Ready Logo Core Conformance Test on Intel D510MO (Atom D510).
>>> It is using userland build with yocto project.
>>>
>>> Test Environment
>>> Test Specification          : 4.0.6
>>> Tool Version                : REL_3_3_2
>>> Test Program Version        : V6LC_5_0_0
>>> Target Device               : Intel D510MO (Atom D510)
>>>
>>> List of FAILs
>>>
>>> Section 4: RFC 1981 - Path MTU Discovery for IPv6
>>> - Test v6LC.4.1.6: Receiving MTU Below IPv6 Minimum Link MTU
>>>      - No. 9 Part A: MTU equal to 56
>>>      - No.10 Part B: MTU equal to 1279
>>>
>>
>> apply this one
>>
>> commit 8013d1d7eafb0589ca766db6b74026f76b7f5cb4
>> Author: Hangbin Liu <liuhangbin@gmail.com>
>> Date:   Thu Jul 30 14:28:42 2015 +0800
>>
>>       net/ipv6: add sysctl option accept_ra_min_hop_limit
>>
>>       Commit 6fd99094de2b ("ipv6: Don't reduce hop limit for an interface")
>>       disabled accept hop limit from RA if it is smaller than the current hop
>>       limit for security stuff. But this behavior kind of break the RFC
>> definition.
>>
>>       RFC 4861, 6.3.4.  Processing Received Router Advertisements
>>          A Router Advertisement field (e.g., Cur Hop Limit, Reachable Time,
>>          and Retrans Timer) may contain a value denoting that it is
>>          unspecified.  In such cases, the parameter should be ignored and the
>>          host should continue using whatever value it is already using.
>>
>>          If the received Cur Hop Limit value is non-zero, the host SHOULD set
>>          its CurHopLimit variable to the received value.
>>
>>       So add sysctl option accept_ra_min_hop_limit to let user choose the
>> minimum
>>       hop limit value they can accept from RA. And set default to 1 to
>> meet RFC
>>       standards.
>>
>>       Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
>>       Acked-by: YOSHIFUJI Hideaki <hideaki.yoshifuji@miraclelinux.com>
>>       Signed-off-by: David S. Miller <davem@davemloft.net>
> 
> I conformed that above patch has been applied at v4.3 in linux.git.
> 
> % git tag --contains=8013d1d7eafb0589ca766db6b74026f76b7f5cb4 | head
> v4.3
> v4.3-rc1
> v4.3-rc2
> v4.3-rc3
> v4.3-rc4
> v4.3-rc5
> v4.3-rc6
> v4.3-rc7
> v4.4
> v4.4-rc1
> 
>>
>>
>>
>>
>>
>> and revert the below one, the TAHI should be updated
>>
>> commit 9d289715eb5c252ae15bd547cb252ca547a3c4f2
>> Author: Hagen Paul Pfeifer <hagen@jauu.net>
>> Date: Thu Jan 15 22:34:25 2015 +0100
>>
>>       ipv6: stop sending PTB packets for MTU < 1280
>>
>>       Reduce the attack vector and stop generating IPv6 Fragment Header for
>>       paths with an MTU smaller than the minimum required IPv6 MTU
>>       size (1280 byte) - called atomic fragments.
>>
>>       See IETF I-D "Deprecating the Generation of IPv6 Atomic Fragments" [1]
>>       for more information and how this "feature" can be misused.
>>
>>       [1]
>> https://tools.ietf.org/html/draft-ietf-6man-deprecate-atomfrag-generation-00
>>
>>       Signed-off-by: Fernando Gont <fgont@si6networks.com>
>>       Signed-off-by: Hagen Paul Pfeifer <hagen@jauu.net>
>>       Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
>>       Signed-off-by: David S. Miller <davem@davemloft.net>
> 
> I will try.

I confirmed that v4.1.20 revert above patch is passed Section 4 No. 9 and 10 testcases
in IPv6 Ready Logo Conformance Test.
I can't immediately revert above patch from v4.6-rc1 by implementation has changed.

I am considering how to fix this problem for mainline.

> 
>>
>>
>>
>> -Roy
>>
>>
>>
>>
>>> Regards,
>>> Yuki Machida
>>>
>>