[BRLTTY] Focus Keyboard not working

[Elias Oltmanns]

Hi Samuel,

On 2023-08-02 at 22:30:21 (+0200), Samuel Thibault <samuel.thibault at ens-lyon.org> wrote:
> Hello,
> Samuel Thibault, le jeu. 20 juil. 2023 19:28:37 +0200, a ecrit:
>> Samuel Thibault, le dim. 16 juil. 2023 23:33:02 +0200, a ecrit:
>> > Dave Mielke, le dim. 16 juil. 2023 12:10:39 -0400, a ecrit:
>> > > [quoted lines by Nicolas Pitre on 2023/07/16 at 00:33 -0400]
>> > > 
>> > > >Best would be to fix the kernel.
>> > > 
>> > > That's happening. My understanding is that, in the 6.4 kernel, Samuel
>> > > has an accepted patch which ignores the sysctl setting if the process
>> > > has CAP_SYS_ADMIN (which brltty does if invoked properly).
>> > 
>> > It is not commited yet, but it was acked by two maintainers, so there's
>> > good hopes that it will be commited for 6.5, and backported to the
>> > affected stable kernels.
>> 
>> It entered greg kh's tty-linus tree, in time for 6.5-rc3 or 6.5-rc4.
> 
> It got into 6.5-rc4 indeed.

Thank you very much, indeed, for taking care of this. I really
appreciate that you saw this problem coming early on and have worked on
a solution so persistently and successfully!

Just out of curiosity: Would it not make sense for the kernel to clear
the input buffer whenever it switches to a context with increased
privileges? If I understand correctly, the sudo exploit would not work
in such a scenario. Since I am not well acquainted with the relevant
kernel subsystems, I may well miss potential side effects that would be
undesirable. So, would do you think about that approach?

Thanks again and best wishes,

Elias