netdev - RE: [net-next v2 6/6] ixgbe: Add malicious driver detection support

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Date:   Tue, 27 Jun 2017 22:14:10 +0000
From:   "Tantilov, Emil S" <emil.s.tantilov@...el.com>
To:     Or Gerlitz <gerlitz.or@...il.com>
CC:     "Kirsher, Jeffrey T" <jeffrey.t.kirsher@...el.com>,
        David Miller <davem@...emloft.net>,
        "Greenwalt, Paul" <paul.greenwalt@...el.com>,
        "Linux Netdev List" <netdev@...r.kernel.org>,
        "nhorman@...hat.com" <nhorman@...hat.com>,
        "sassmann@...hat.com" <sassmann@...hat.com>,
        "jogreene@...hat.com" <jogreene@...hat.com>
Subject: RE: [net-next v2 6/6] ixgbe: Add malicious driver detection support

>-----Original Message-----
>From: Or Gerlitz [mailto:gerlitz.or@...il.com]
>Sent: Tuesday, June 27, 2017 2:07 PM
>To: Tantilov, Emil S <emil.s.tantilov@...el.com>
>Cc: Kirsher, Jeffrey T <jeffrey.t.kirsher@...el.com>; David Miller
><davem@...emloft.net>; Greenwalt, Paul <paul.greenwalt@...el.com>; Linux
>Netdev List <netdev@...r.kernel.org>; nhorman@...hat.com;
>sassmann@...hat.com; jogreene@...hat.com
>Subject: Re: [net-next v2 6/6] ixgbe: Add malicious driver detection
>support
>
>On Tue, Jun 27, 2017 at 11:59 PM, Tantilov, Emil S
><emil.s.tantilov@...el.com> wrote:
>>>-----Original Message-----
>>>From: netdev-owner@...r.kernel.org [mailto:netdev-owner@...r.kernel.org]
>On
>>>Behalf Of Or Gerlitz
>>>Sent: Tuesday, June 27, 2017 2:08 AM
>>>To: Kirsher, Jeffrey T <jeffrey.t.kirsher@...el.com>
>>>Cc: David Miller <davem@...emloft.net>; Greenwalt, Paul
>>><paul.greenwalt@...el.com>; Linux Netdev List <netdev@...r.kernel.org>;
>>>nhorman@...hat.com; sassmann@...hat.com; jogreene@...hat.com
>>>Subject: Re: [net-next v2 6/6] ixgbe: Add malicious driver detection
>>>support
>>>
>>>On Tue, Jun 27, 2017 at 11:51 AM, Jeff Kirsher
>>><jeffrey.t.kirsher@...el.com> wrote:
>>>> From: Paul Greenwalt <paul.greenwalt@...el.com>
>>>>
>>>> Add malicious driver detection (MDD) support for X550, X550em_a,
>>>> and X550em_x devices.
>>>>
>>>> MDD is a hardware SR-IOV security feature which the driver enables by
>>>> default, but can be controlled on|off by ethtool set-priv-flags
>>>
>>>wait, we have the trusted vf concept, which you implement
>>>(ixgbe_ndo_set_vf_trust)
>>>so you can enable by default for all vfs and disable it for trusted
>>>ones, why create[]  an ixgbe special config knob? IMHO we should max all
>possible efforts to
>>>avoid priv ethtool flags usage.
>>
>> The "trusted" option was added to allow use cases that were not possible in the
>> default driver configuration for SRIOV (promiscuous mode, overriding the MAC).
>> While these modes can lead to issues (performance with promisc) they can still
>> be useful for certain configurations.
>>
>> MDD is a completely different type of protection that incorporates checks for
>> queue context, Tx descriptors and out-of-bounds DMA/memory access that can
>> disrupt the operation of the interfaces. You can read more about it in the X550
>> datasheet (section 7.9.4.3 malicious Driver Detection):
>>
>https://www.intel.com/content/www/us/en/embedded/products/networking/ethern
>et-controller-x550-family-documentation.html
>>
>> For that reason we do not want to make it part of the "trusted" option.
>
>you can extend the trusted option without breaking the UAPI, currently
>it's one bit y/n, but you should have there at least seven more bits
>to use.
>
>> In addition MDD is a global setting and cannot be configured per-VF.
>
>can you state more clearly why use think the right configuration knob
>here is per driver ethtool private flag?

Mainly because I am not sure that other (non-Intel) drivers will benefit from
such an option. In normal operation this functionality should not cause issues
and if it doesn't we may be able to deprecate the private flag in the future.

On the other hand if the same/similar feature exists in other drivers then
it would perhaps make more sense to introduce a new option altogether.

Thanks,
Emil