From: David Ahern <dsa@cumulusnetworks•com>
To: "Eric W. Biederman" <ebiederm@xmission•com>
Cc: Sowmini Varadhan <sowmini05@gmail•com>,
netdev <netdev@vger•kernel.org>,
Shrijeet Mukherjee <shm@cumulusnetworks•com>,
Roopa Prabhu <roopa@cumulusnetworks•com>,
Andy Gospodarek <gospo@cumulusnetworks•com>,
jtoppins@cumulusnetworks•com, nikolay@cumulusnetworks•com,
ddutt@cumulusnetworks•com,
Hannes Frederic Sowa <hannes@stressinduktion•org>,
Nicolas Dichtel <nicolas.dichtel@6wind•com>,
Stephen Hemminger <stephen@networkplumber•org>,
hadi@mojatatu•com, David Miller <davem@davemloft•net>
Subject: Re: [RFC net-next 3/6] net: Introduce VRF device driver - v2
Date: Fri, 10 Jul 2015 12:42:35 -0600 [thread overview]
Message-ID: <55A0121B.8090408@cumulusnetworks.com> (raw)
In-Reply-To: <87wpy84nlb.fsf@x220.int.ebiederm.org>
On 7/9/15 10:56 PM, Eric W. Biederman wrote:
> I have given specific areas of concern, and explained myself and you are
> blowing me off.
You have not had answered my question with any additional details or
code references -- ie., a specific example. Asking you for clarification
and details is not blowing you off.
To recap:
Eric: "With respect to sockets there is also the issue that ip addresses
are not per vrf."
David: "IP addresses are per interface and interfaces are uniquely
assigned to a VRF so why do you think IP addresses are not per VRF?"
Eric: "I have read large swaths of the linux networking code over the
years. Further I was thinking more about non-local addresses ip
addresses, but I would not be surprised if there are also issues with
local addresses."
David: "Well, if someone has a specific example I'll take a look."
So, let me try this again: All of the IPv4 and IPv6 addresses I am aware
of are held in structs linked to a specific netdevice. Can you give me a
specific example of what you mean here? I can't respond to your feedback
based on the little information you have given me.
>
> Besides the fragment reassembly and xfrm there are things like the
> ineetpeer cache.
noted.
>
>>>>> Which means things like packet fragmentation reassembly
>>>>> can easily do the wrong thing. Similarly things like the xfrm for ipsec
>>>>> tunnels are not hooked into this mix.
>>>>>
>>>>> So I really do not see how this VRF/MRF thing as designed can support
>>>>> general purpose sockets. I am not certain it can correctly support any
>>>>> kind of socket except perhaps SOCK_RAW.
>>>>
>>>> Sockets bound to the VRF device work properly. Why do you think they won't?
>>>
>>> Because there are many locations in the network stack (like fragment
>>> reassembly) that make the assumption that ip addresses are unique and
>>> do not bother looking at network device or anything else. If fragments
>>> manage to come into play I don't expect it would be hard to poision a
>>> connections with fragments from another routing domain with overlapping
>>> ip addresses.
>>
>> If that is true it is a problem with the networking stack today and is
>> completely independent of this VRF proposal.
>
> Not at all. It is required functionality for reassembly of ip fragments
> when the packets come in via different paths. This is required to
> support multi-path ip reception.
>
> This only becomes a bug in the scenario you have proposed.
Can you please point to a specific line in one of these patches that
impacts fragmentation?
This patch -- patch 3 -- adds a VRF driver. It has not mucked with
packets at all.
Patch 4 (again I have a better split in a forthcoming revision) tweaks a
few places in the IPv4 stack with respect to socket lookups (dif
modified) and FIB table lookups (specifying a table to use or tweaking
oif/iif).
Since the VRF device has not touched the packet and does not introduce a
tunnel how has its use/existence impacted fragmentation?
I do plan tests to include ipsec for example and fragmentation; it's a
matter of time. If you have suggestions on a setup/test case I should
include please let me know.
David
next prev parent reply other threads:[~2015-07-10 18:42 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-06 15:03 [RFC net-next 0/6] Proposal for VRF-lite - v2 David Ahern
2015-07-06 15:03 ` [RFC net-next 1/6] fib: export symbols David Ahern
2015-07-06 15:03 ` [RFC net-next 2/6] net: Preparation for vrf device David Ahern
2015-07-08 8:37 ` Nicolas Dichtel
2015-07-08 8:40 ` Nicolas Dichtel
2015-07-08 16:10 ` David Ahern
2015-07-06 15:03 ` [RFC net-next 3/6] net: Introduce VRF device driver - v2 David Ahern
2015-07-06 15:42 ` Nicolas Dichtel
2015-07-06 16:37 ` Nikolay Aleksandrov
2015-07-06 16:46 ` David Ahern
2015-07-08 9:27 ` Nicolas Dichtel
2015-07-08 16:38 ` David Ahern
2015-07-08 18:34 ` Sowmini Varadhan
2015-07-09 17:19 ` David Ahern
2015-07-09 17:28 ` Sowmini Varadhan
2015-07-10 1:36 ` Eric W. Biederman
2015-07-10 2:12 ` David Ahern
2015-07-10 3:55 ` Eric W. Biederman
2015-07-10 4:20 ` David Ahern
2015-07-10 4:56 ` Eric W. Biederman
2015-07-10 18:42 ` David Ahern [this message]
2015-07-10 2:39 ` David Ahern
2015-07-10 3:28 ` Sowmini Varadhan
2015-07-10 3:44 ` David Ahern
2015-07-06 15:03 ` [RFC net-next 4/6] net: Modifications to ipv4 stack for VRF devices David Ahern
2015-07-06 15:03 ` [RFC net-next 5/6] net: Add sk_bind_dev_if to task_struct David Ahern
2015-07-06 15:03 ` [RFC net-next 6/6] net: Add chvrf command David Ahern
2015-07-06 15:03 ` [RFC PATCH] iproute2: Add support for VRF device David Ahern
2015-07-06 15:40 ` [RFC net-next 0/6] Proposal for VRF-lite - v2 Nicolas Dichtel
2015-07-06 17:53 ` Shrijeet Mukherjee
2015-07-08 9:30 ` Nicolas Dichtel
2015-07-10 5:14 ` Scott Feldman
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