netdev - Re: [PATCH net] net: ipv6: Fix ping to link-local addresses.

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Date:	Tue, 9 Aug 2016 11:36:10 +0200
From:	Hannes Frederic Sowa <hannes@...essinduktion.org>
To:	YOSHIFUJI Hideaki <hideaki.yoshifuji@...aclelinux.com>,
	Erik Kline <ek@...gle.com>, David Miller <davem@...emloft.net>
Cc:	Lorenzo Colitti <lorenzo@...gle.com>,
	netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH net] net: ipv6: Fix ping to link-local addresses.

On 09.08.2016 10:37, YOSHIFUJI Hideaki wrote:
> 
> 
> Erik Kline wrote:
>> On 9 August 2016 at 14:20, David Miller <davem@...emloft.net> wrote:
>>> From: Lorenzo Colitti <lorenzo@...gle.com>
>>> Date: Tue, 9 Aug 2016 10:00:25 +0900
>>>
>>>> Note that pretty much every sendmsg codepath allows other data to take
>>>> precedence over sk_bound_dev_if:
>>>>
>>>> - udpv6_sendmsg: if sin6_scope_id specified on a scoped address
>>>> - rawv6_sendmsg: if sin6_scope_id specified on a scoped address
>>>> - l2tp_ip6_sendmsg: if sin6_scope_id specified on a scoped address
>>>> - ip_cmsg_send: if IP_PKTINFO or IPV6_PKTINFO specified
>>>>
>>>> What should I do about those? -EINVAL? Ignore the conflicting data? Leave as is?
>>>
>>> That's a good point, I guess this needs some more thought.
>>
>> I could see a point of view that says when bound_if is in play sending
>> to destinations on/via other interfaces--by any mechanism--should
>> effectively get ENETUNREACH (or something).
> 
> +1
> 
>>
>> That does seem like I would involve changing some existing behavior, though.
>>
> 
> The use of sin6_scope_id and SO_BINDTODEVICE with different interfaces
> is incorrect and should be rejected.

I agree, I would actually change the behavior at this point, as it also
could have security consequences from a network pov.

Bye,
Hannes