netdev - Re: [RFC PATCH net-next v3 1/4] net core: Add IFF_PROTO

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CACcJQnQyW7GWp42AuRBwKpzVRAGnXoB7ddtcURW5GxDa_4wKKQ@mail.gmail.com>
Date:	Wed, 29 Apr 2015 16:25:07 -0700
From:	Anuradha Karuppiah <anuradhak@...ulusnetworks.com>
To:	Stephen Hemminger <stephen@...workplumber.org>
Cc:	"David S. Miller" <davem@...emloft.net>,
	Scott Feldman <sfeldma@...il.com>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	Roopa Prabhu <roopa@...ulusnetworks.com>,
	Andy Gospodarek <gospo@...ulusnetworks.com>,
	Wilson Kok <wkok@...ulusnetworks.com>
Subject: Re: [RFC PATCH net-next v3 1/4] net core: Add IFF_PROTO_DOWN support.

On Wed, Apr 29, 2015 at 4:07 PM, Anuradha Karuppiah
<anuradhak@...ulusnetworks.com> wrote:
> On Wed, Apr 29, 2015 at 3:13 PM, Stephen Hemminger
> <stephen@...workplumber.org> wrote:
>> On Mon, 27 Apr 2015 10:38:21 -0700
>> anuradhak@...ulusnetworks.com wrote:
>>
>>> From: Anuradha Karuppiah <anuradhak@...ulusnetworks.com>
>>>
>>> This patch introduces an IFF_PROTO_DOWN flag that can be used by
>>> user space applications to notify drivers that errors have been
>>> detected on the device.
>>>
>>> Signed-off-by: Anuradha Karuppiah <anuradhak@...ulusnetworks.com>
>>> Signed-off-by: Andy Gospodarek <gospo@...ulusnetworks.com>
>>> Signed-off-by: Roopa Prabhu <roopa@...ulusnetworks.com>
>>> Signed-off-by: Wilson Kok <wkok@...ulusnetworks.com>
>>
>> I worry that adding another bit to an already complex state API
>> will break userspace.
>>
>> There are lots of things besides iproute2 which look at those
>> flags including routing daemons (quagga), network manager, netplugd,
>> and switch controllers.
>
> Yes, I understand your concerns here. And tried to work around introducing
> a separate error flag by clearing IFF_UP on proto_down/detecting errors (as
> Scott also brought up earlier).
>
> That implementation failed because of the following reasons -
> 1. There is no way to disambiguate between admin_down (!IFF_UP) and an
> APP/driver enforced error_down (IFF_PROTO_DOWN). Administrator or
> automation-scripts that monitor the config assumed that switch-port
> configuration had somehow fallen out of sync (and attempted to reinstate the
> admin_up repeatedly).
>
> 2. Automatic error recovery was not possible; consider the following scenario
> for e.g.
>    a. The MLAG peer-link is down so the MLAG app on the secondary switch has
>       proto_down’ed all the MLAG ports (including switch-port swp1) by clearing
>       IFF_UP.
>    b. At the same time the administrator is in the process of making some
>       changes on the network connected to swp1. To avoid doing it live he would
>       admin_disable swp1 (!IFF_UP) by doing an "ip link set swp1 down" (this
>       is a no-op as event #a has already cleared IFF_UP on swp1).
>    c. If the MLAG peer-link recovers at this point the MLAG app on the
>       secondary switch would try to automatically recover the MLAG ports
>       by clearing proto_down (i.e. setting IFF_UP); including on swp1. Doing
>       that overrides the administrator’s directive to keep swp1 admin_down.
>       Overriding an admin-down in a live network can be very dangerous so it
>       is not possible to do auto-error-recovery unless we have a way to
>       disambiguate between the admin and error states.

I have the need to disambiguate the error state but it doesn't have to be an
IFF_X attribute. Stephen, Do you think it would be more easily consumable if
it were a new/separate net_device attribute instead of being a new bit in
"&struct net_device flags"?
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html