netdev - Re: [BUG] VPN broken in net-next

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Date:	Thu, 3 Mar 2011 14:41:55 +0200 (EET)
From:	Julian Anastasov <ja@....bg>
To:	David Miller <davem@...emloft.net>
cc:	shemminger@...tta.com, netdev@...r.kernel.org
Subject: Re: [BUG] VPN broken in net-next


 	Hello,

On Wed, 2 Mar 2011, David Miller wrote:

>> I really need to know what addresses interfaces have the time of the
>> __ip_dev_find() call which, if I'm not mistaken, is before the VPN is
>> up.
>
> Looking at pptp_connect(), it seems to be trying to do a route lookup
> using the source address, before it registers the PPP channel and that
> even gets brought up.
>
> I suspect that was working by luck previously, and it was getting the
> default route out perhaps another interface.  If that is the case,
> removing the explicit "fl4_src" source address specification in the lookup
> flow pptp_connect() uses should fix the problem.

 	May be the problem is in inet_hash_insert(), it should
hash ifa_local, not ifa_address. May be they are equal for
the common case but not for peer addresses. In devinet_ioctl()
we can see they are equal initially:

ifa->ifa_address = ifa->ifa_local = sin->sin_addr.s_addr;

 	but later SIOCSIFDSTADDR can change ifa_address which
is destination address from the same prefix:

ifa->ifa_address = sin->sin_addr.s_addr;

 	fib_add_ifaddr() does more things but not for this
case with /32 mask, so the problem should be in using
ifa_address instead of ifa_local.

Regards

--
Julian Anastasov <ja@....bg>
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