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

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Message-ID: <4bc70116-abe4-c922-5a16-2a1c036bcf4d@cumulusnetworks.com>
Date:	Fri, 12 Aug 2016 10:04:15 -0600
From:	David Ahern <dsa@...ulusnetworks.com>
To:	Lorenzo Colitti <lorenzo@...gle.com>,
	YOSHIFUJI Hideaki <hideaki.yoshifuji@...aclelinux.com>
Cc:	Erik Kline <ek@...gle.com>, David Miller <davem@...emloft.net>,
	netdev <netdev@...r.kernel.org>,
	Hannes Frederic Sowa <hannes@...essinduktion.org>
Subject: Re: [PATCH net] net: ipv6: Fix ping to link-local addresses.

On 8/12/16 9:45 AM, Lorenzo Colitti wrote:
> On Wed, Aug 10, 2016 at 7:44 AM, YOSHIFUJI Hideaki
> <hideaki.yoshifuji@...aclelinux.com> wrote:
>>
>>>> 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).
>>>
>>> VRF uses this capability to send on an enslaved interface. ie., socket is bound to VRF device to limit packets to that L3 domain and then uses PKTINFO to force a packet out a particular interface.
>>
>> We could extend our code to allow enslave devices, maybe.
> 
> So something like this, then?
> 
> static inline bool inet_check_bound_oif(const struct sock *sk, int oif)
> {
>         if (!oif || !sk->sk_bound_dev_if || oif == sk->sk_bound_dev_if)
>                 return true;
> 
> #ifdef CONFIG_NET_L3_MASTER_DEV
>         return l3mdev_master_ifindex_by_index(sock_net(sk), oif) ==
>                 sk->sk_bound_dev_if;
> #endif
> 
>         return false;
> }

The ifdef is not needed; it's already in the l3mdev macros.

	int midx;

	if (!oif || !sk->sk_bound_dev_if || oif == sk->sk_bound_dev_if)
		return true;

	midx = l3mdev_master_ifindex_by_index(sock_net(sk), oif);
	if (midx && sk->sk_bound_dev_if == midx)
		return true;

	return false;

> 
> and then in the various sendmsg functions:
> 
>         if (!inet_check_bound_oif(sk, oif))
>                 return -EINVAL;
>