Re: [PATCH] drivers: connector: cn_proc: allow limiting certain messages

From: David Miller
Date: Mon Feb 17 2020 - 21:52:39 EST

From: "Daniel Walker (danielwa)" <danielwa@xxxxxxxxx>
Date: Mon, 17 Feb 2020 17:52:11 +0000

> On Mon, Feb 17, 2020 at 08:44:35PM +0300, Evgeniy Polyakov wrote:
>> Hi Daniel, David
>> 17.02.2020, 20:26, "Daniel Walker (danielwa)" <danielwa@xxxxxxxxx>:
>> > On Sun, Feb 16, 2020 at 06:44:43PM -0800, David Miller wrote:
>> >> This is a netlink based facility, therefore please you should add
>> filtering
>> >> capabilities to the netlink configuration and communications path.
>> >>
>> >> Module parameters are quite verboten.
>> >
>> > How about adding in Kconfig options to limit the types of messages? The
>> issue
>> > with this interface is that it's very easy for someone to enable the
>> interface
>> > as a listener, then never turn the interface off. Then it becomes a
>> broadcast
>> > interface. It's desirable to limit the more noisy messages in some
>> cases.
>> Compile-time options are binary switches which live forever after kernel
>> config has been created, its not gonna help those who enabled messages.
>> Kernel modules are kind of no-go, since it requires reboot to change in
>> some cases.
>> Having netlink control from userspace is a nice option, and connector has
>> simple userspace->kernelspace channel,
>> but it requires additional userspace utils or programming, which is still
>> cumbersome.
>> What about sysfs interface with one file per message type?
> You mean similar to the module parameters I've done, but thru sysfs ? It would
> work for Cisco. I kind of like Kconfig because it also reduces kernel size for
> messages you may never want to see.

Even the sysfs has major downsides, as it fails to take the socket context into
consideration and makes a system wide decision for what should be a per service