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From: Paolo Abeni <pabeni@redhat.com>
To: Matthieu Baerts <matthieu.baerts@tessares.net>,
	Mat Martineau <mathew.j.martineau@linux.intel.com>
Cc: mptcp@lists.linux.dev
Subject: Re: [PATCH mptcp-next] mptcp: full fully established support after ADD_ADDR
Date: Fri, 13 Aug 2021 16:14:44 +0200	[thread overview]
Message-ID: <5b996b3fc540926a129c2f0c45634def94074f01.camel@redhat.com> (raw)
In-Reply-To: <e8ce0aa4-c8a5-8907-396e-be420aec6fe4@tessares.net>

On Fri, 2021-08-13 at 13:06 +0200, Matthieu Baerts wrote:
> Hi Mat,
> 
> Thank you for your review!
> 
> On 13/08/2021 00:30, Mat Martineau wrote:
> > On Thu, 12 Aug 2021, Matthieu Baerts wrote:
> > 
> > > If directly after an MP_CAPABLE 3WHS, the client receives a valid
> > > ADD_ADDR from the server, it is enough to prove exchanged MPTCP options
> > > are valid. Indeed, the ADD_ADDR contains an HMAC generated using both
> > > the client and server keys.
> > 
> > The ADD_ADDR HMAC is validated after the call to
> > check_fully_established(), so I'm not sure this condition is fully met
> > with the patch as-is. Looks like an ADD_ADDR with a bad HMAC could
> > change the fully_established flag when it shouldn't.
> That's a very good point.
> 
> If I'm not mistaken, we have the same issue when receiving a DATA_ACK:
> here we just check if one is present, not if it is valid, no?
> 
> Should we delay when we mark subflows and msks as "fully established" or
> is it not an issue to be in "fully established" too soon?

I *think* we could/should start with this simpler implementation/fix -
eventually adding a comment explaining the problematic scenario.

A more correct state handling requires more extensive changes, likely
too invasive for a resonably timely fix.

Cheers,

Paolo


  reply	other threads:[~2021-08-13 14:14 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-12 16:27 [PATCH mptcp-next] mptcp: full fully established support after ADD_ADDR Matthieu Baerts
2021-08-12 16:33 ` Paolo Abeni
2021-08-12 22:30 ` Mat Martineau
2021-08-13 11:06   ` Matthieu Baerts
2021-08-13 14:14     ` Paolo Abeni [this message]
2021-08-14  0:37       ` Mat Martineau

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