Re: [PATCH v4l-utils v2 2/2] keytable: cannot load BPF decoders from udevd

[Sean Young <sean@mess.org>]

Hi Hans,

On Sun, Oct 27, 2019 at 03:18:55PM +0100, Hans Verkuil wrote:
> Hi Sean,
> 
> After this was installed on my debian system (running the 'testing' version
> of debian) the laptop would no longer boot since the systemd-udevd service
> failed to load.
> 
> My laptop runs systemd 242.
> 
> After removing the installed 50-rc_keymap.conf it worked again.
> 
> So either this file is no good, or it requires a newer systemd for it to
> work.

I think I know what the problem is. On Fedora, for the systemd-udevd.service
there is this setting.
SystemCallFilter=@system-service @module @raw-io
then 50-rc_keymap.conf adds:
SystemCallFilter=bpf
Which is concatenated to the end.

On the debian version of systemd, SystemCallFilter is not set. So
SystemCallFilter=bpf
means that only the bpf syscall is allowed. 

I'm not sure what the correct solution is. I'll try a few things and if I
don't come up with anything, I'll have to revert.

Suggestions welcome :)

Thanks for debugging and reporting.


Sean