netdev - Re: [PATCH] net/ipv6: add sysctl option accept_ra_hop

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Date:	Fri, 24 Jul 2015 19:12:16 +0800
From:	Hangbin Liu <liuhangbin@...il.com>
To:	YOSHIFUJI Hideaki <hideaki.yoshifuji@...aclelinux.com>
Cc:	network dev <netdev@...r.kernel.org>,
	Hannes Frederic Sowa <hannes@...essinduktion.org>
Subject: Re: [PATCH] net/ipv6: add sysctl option accept_ra_hop_limit

2015-07-24 12:48 GMT+08:00 YOSHIFUJI Hideaki
<hideaki.yoshifuji@...aclelinux.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.
>>
>> Signed-off-by: Hangbin Liu <liuhangbin@...il.com>
>> Acked-by: Hannes Frederic Sowa <hannes@...essinduktion.org>
>> ---
>>  Documentation/networking/ip-sysctl.txt | 11 +++++++++++
>>  include/linux/ipv6.h                   |  1 +
>>  include/uapi/linux/ipv6.h              |  1 +
>>  net/ipv6/addrconf.c                    | 10 ++++++++++
>>  net/ipv6/ndisc.c                       | 17 +++++++++++------
>>  5 files changed, 34 insertions(+), 6 deletions(-)
>>
> :
>> diff --git a/include/uapi/linux/ipv6.h b/include/uapi/linux/ipv6.h
>> index 5efa54a..9f40ac9 100644
>> --- a/include/uapi/linux/ipv6.h
>> +++ b/include/uapi/linux/ipv6.h
>> @@ -153,6 +153,7 @@ enum {
>>       DEVCONF_FORCE_MLD_VERSION,
>>       DEVCONF_ACCEPT_RA_DEFRTR,
>>       DEVCONF_ACCEPT_RA_PINFO,
>> +     DEVCONF_ACCEPT_RA_HOP_LIMIT,
>>       DEVCONF_ACCEPT_RA_RTR_PREF,
>>       DEVCONF_RTR_PROBE_INTERVAL,
>>       DEVCONF_ACCEPT_RA_RT_INFO_MAX_PLEN,
>
> No, you cannot add new one in the middle of these since
> values are exported to userspace.
>
Hi Yoshfuji-san,

Thanks for the reminding, should I also move the value in struct ipv6_devconf
to the end or just leave after accept_ra_pinfo?

Thanks
Hangbin
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