Hangbin Liu wrote:
> 2015-07-28 11:58 GMT+08:00 YOSHIFUJI Hideaki
> <hideaki.yoshif...@miraclelinux.com>:
>> Hi,
>>
>> Hangbin Liu wrote:
>>> 2015-07-28 7:50 GMT+08:00 YOSHIFUJI Hideaki/吉藤英明
>>> <hideaki.yoshif...@miraclelinux.com>:
>>>> Hi,
>>>>
>>>> Hangbin Liu wrote:
>>>>> Commit 6fd99094de2b ("ipv6: Don't reduce hop limit for an interface")
>>>>> disabled accept hop limit from RA if it is higher 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
>>>>> 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_hop_limit to let user choose whether accept
>>>>> hop limit info in RA.
>>>>>
>>>>
>>>> How about introducing "minimum hop limit", instead?
>>>
>>> Hi Yoshifuji,
>>>
>>> This is a good idea. Maybe this can be another sysctl option?
>>>
>>> The minimum hop limit can be an enhancement of the security issue, then we
>>> will
>>> not only increase the hop limit, but also could decrease it in the
>>> range of values we
>>> accept.
>>>
>>> On the other hand, with this patch, we can enable, disable or partly
>>> enable accept
>>> hop limit. If we only use "minimum hop limit", people could not use a
>>> static hop
>>> limit value.
>>>
>>> May be we use a “hop limit range" instead? How do you think?
>>
>> I think name of sysctl is the same as you suggested and change the
>> semantics. default value is 0 to accept all hotlimit value
>> as before and people can set it to 32 (for example) to reject
>> too-small hoplimit (0-31).
>
> OK, then I will try submit a "minimum hop limit", thanks for your suggestion
> :)
accept_ra_min_hop_limit would be better as we have
accept_ra_rt_info_max_plen.
>
> Regards
> Hangbin
>>
>> --yoshfuji
>>
>>>
>>> Thanks
>>> Hangbin
>>>
>>>>
>>>> |commit 6fd99094de2b83d1d4c8457f2c83483b2828e75a
>>>> |Author: D.S. Ljungmark <ljungm...@modio.se>
>>>> |Date: Wed Mar 25 09:28:15 2015 +0100
>>>> |
>>>> | ipv6: Don't reduce hop limit for an interface
>>>> :
>>>> | RFC 3756, Section 4.2.7, "Parameter Spoofing"
>>>> |
>>>> :
>>>> | > As an example, one possible approach to mitigate this threat is to
>>>> | > ignore very small hop limits. The nodes could implement a
>>>> | > configurable minimum hop limit, and ignore attempts to set it
>>>> below
>>>> | > said limit.
>>
>> --
>> Hideaki Yoshifuji <hideaki.yoshif...@miraclelinux.com>
>> Technical Division, MIRACLE LINUX CORPORATION
--
Hideaki Yoshifuji <hideaki.yoshif...@miraclelinux.com>
Technical Division, MIRACLE LINUX CORPORATION
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