[RFD] Network configuration data in sysfs

[RFD] Network configuration data in sysfs

[Kirill A. Shutemov]

Hi,

Currently there's no way to set or inspect network configuration (protocol
addresses, routes, etc.) through sysfs. Yes, we have netlink interface for
this, but sysfs has advantage:

- change or inspect network configuration using standard unix utilities
  (echo, cat, etc.). It's useful at least in restricted environment where
  no special utilities available -- initrd or stripped down busybox.

- transparent udev support. It would be nice to get this information to
  udev.

Is there something fundamental preventing us to have sysfs interface for
network configuration?

-- 
 Kirill A. Shutemov

Re: [RFD] Network configuration data in sysfs

[David Miller]

From: "Kirill A. Shutemov" <kirill@shutemov.name>
Date: Mon, 24 Oct 2011 02:35:58 +0300

> Is there something fundamental preventing us to have sysfs interface for
> network configuration?

Netlink already provides everything sysfs would potentially provide as
well as event tracking.

udev could just listen to a netlink socket and notice all changes to
addresses, routes, and device states.

Re: [RFD] Network configuration data in sysfs

[Kirill A. Shutemov]

On Sun, Oct 23, 2011 at 08:49:43PM -0400, David Miller wrote:
> From: "Kirill A. Shutemov" <kirill@shutemov.name>
> Date: Mon, 24 Oct 2011 02:35:58 +0300
> 
> > Is there something fundamental preventing us to have sysfs interface for
> > network configuration?
> 
> Netlink already provides everything sysfs would potentially provide as
> well as event tracking.

Not everything. You still need special utilities to view/change the
configuration.

> udev could just listen to a netlink socket and notice all changes to
> addresses, routes, and device states.

Yes, potentially. I'm not sure if it fits well to udev design.
Kay, any comments?

-- 
 Kirill A. Shutemov

Re: [RFD] Network configuration data in sysfs

[David Miller]

From: "Kirill A. Shutemov" <kirill@shutemov.name>
Date: Mon, 24 Oct 2011 04:34:07 +0300

> On Sun, Oct 23, 2011 at 08:49:43PM -0400, David Miller wrote:
>> From: "Kirill A. Shutemov" <kirill@shutemov.name>
>> Date: Mon, 24 Oct 2011 02:35:58 +0300
>> 
>> > Is there something fundamental preventing us to have sysfs interface for
>> > network configuration?
>> 
>> Netlink already provides everything sysfs would potentially provide as
>> well as event tracking.
> 
> Not everything. You still need special utilities to view/change the
> configuration.

You can use netlink to perform any configuration change you want, or
to view any network configuration setting.

Re: [RFD] Network configuration data in sysfs

[Kirill A. Shutemov]

On Sun, Oct 23, 2011 at 11:24:16PM -0400, David Miller wrote:
> From: "Kirill A. Shutemov" <kirill@shutemov.name>
> Date: Mon, 24 Oct 2011 04:34:07 +0300
> 
> > On Sun, Oct 23, 2011 at 08:49:43PM -0400, David Miller wrote:
> >> From: "Kirill A. Shutemov" <kirill@shutemov.name>
> >> Date: Mon, 24 Oct 2011 02:35:58 +0300
> >> 
> >> > Is there something fundamental preventing us to have sysfs interface for
> >> > network configuration?
> >> 
> >> Netlink already provides everything sysfs would potentially provide as
> >> well as event tracking.
> > 
> > Not everything. You still need special utilities to view/change the
> > configuration.
> 
> You can use netlink to perform any configuration change you want, or
> to view any network configuration setting.

You need /sbin/ip or similar tool to do this, right?

-- 
 Kirill A. Shutemov

Re: [RFD] Network configuration data in sysfs

[David Miller]

From: "Kirill A. Shutemov" <kirill@shutemov.name>
Date: Mon, 24 Oct 2011 07:24:00 +0300

> On Sun, Oct 23, 2011 at 11:24:16PM -0400, David Miller wrote:
>> From: "Kirill A. Shutemov" <kirill@shutemov.name>
>> Date: Mon, 24 Oct 2011 04:34:07 +0300
>> 
>> You can use netlink to perform any configuration change you want, or
>> to view any network configuration setting.
> 
> You need /sbin/ip or similar tool to do this, right?

I'm talking about udev using netlink natively.

Re: [RFD] Network configuration data in sysfs

[Kay Sievers]

On Mon, Oct 24, 2011 at 06:59, David Miller <davem@davemloft.net> wrote:
> From: "Kirill A. Shutemov" <kirill@shutemov.name>
> Date: Mon, 24 Oct 2011 07:24:00 +0300
>
>> On Sun, Oct 23, 2011 at 11:24:16PM -0400, David Miller wrote:
>>> From: "Kirill A. Shutemov" <kirill@shutemov.name>
>>> Date: Mon, 24 Oct 2011 04:34:07 +0300
>>>
>>> You can use netlink to perform any configuration change you want, or
>>> to view any network configuration setting.
>>
>> You need /sbin/ip or similar tool to do this, right?
>
> I'm talking about udev using netlink natively.

Kirill, what exactly is the use case? And why what does udev support
mean in that context?

I doubt that "not having /sbin/ip installed" should be a reason to add
and expose complex interfaces in /sys, while we already have a
perfectly working native way to do it.

Kay

Re: [RFD] Network configuration data in sysfs

[Alexey Gladkov]

24.10.2011 16:46, Kay Sievers wrote:
> Kirill, what exactly is the use case? And why what does udev support
> mean in that context?
> 
> I doubt that "not having /sbin/ip installed" should be a reason to add
> and expose complex interfaces in /sys, while we already have a
> perfectly working native way to do it.

Adding NETLINK_ROUTE in udev is a way to perform some actions in case
of network events without polling. Now there are only a few specific
daemons (NM, connman etc) that are listen to the netlink socket and
setup the network his own way.

-- 
Rgrds, legion

Re: [RFD] Network configuration data in sysfs

[Kay Sievers]

On Tue, Oct 25, 2011 at 01:54, Alexey Gladkov <gladkov.alexey@gmail.com> wrote:
> 24.10.2011 16:46, Kay Sievers wrote:
>> Kirill, what exactly is the use case? And why what does udev support
>> mean in that context?
>>
>> I doubt that "not having /sbin/ip installed" should be a reason to add
>> and expose complex interfaces in /sys, while we already have a
>> perfectly working native way to do it.
>
> Adding NETLINK_ROUTE in udev is a way to perform some actions in case
> of network events without polling. Now there are only a few specific
> daemons (NM, connman etc) that are listen to the netlink socket and
> setup the network his own way.

I'm not really convinced that udev should be in charge of network
config changes, it's a really complex area. Udev is a generic kernel
device manager, not a network setup manager.

Our point of view is, that all services depending on network state
changes should listen to netlink themselves, and not be worked around
with tools like udev to execute stuff and notify them.

But again, what's the use-case for that you have in mind?

Kay

Re: [RFD] Network configuration data in sysfs

[Stephen Hemminger]

On Mon, 24 Oct 2011 02:35:58 +0300
"Kirill A. Shutemov" <kirill@shutemov.name> wrote:

> Hi,
> 
> Currently there's no way to set or inspect network configuration (protocol
> addresses, routes, etc.) through sysfs. Yes, we have netlink interface for
> this, but sysfs has advantage:
> 
> - change or inspect network configuration using standard unix utilities
>   (echo, cat, etc.). It's useful at least in restricted environment where
>   no special utilities available -- initrd or stripped down busybox.

Last I checked busybox had a stripped down version of iproute arealdy.

> - transparent udev support. It would be nice to get this information to
>   udev.
> 
> Is there something fundamental preventing us to have sysfs interface for
> network configuration?
> 

Sysfs does not support the concept of transactions. Many network operations
require setting multiple values at a time; which is why a message interface
like netlink works much better.