Re: [GIT PULL] SCSI fixes for 4.18-rc3

Linus Torvalds
2018-07-07T02:39:42Z

On Fri, Jul 6, 2018 at 7:31 PM Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> Who actually does direct read/write to /dev/sg? Could we perhaps just
> add a config option to disable it entirely?

On the IB side, the argument was that there was some crazy binary-only
vendor management code that really wanted to use this completely crazy
interface.

I also think that the warnings are dubious. I'd rather add a
deprecation warning to the whole "read/write to /dev/sg" itself, and
then do what we did for ib_safe_file_access(), which was to just have
the permission checks.

It's not like a normal person should have access to /dev/sg to begin
with. So it's not like you can open /dev/sg0 and then try to fool a
suid program into doing the actual IO.

I'd hope.

Maybe I'm wrong, and there's some crazy "let's make /dev/sg available
to normal users" setup out there somewhere. At least for me, /dev/sg
isn't accessible to normal people:

[torvalds@i7 linux]$ cat /dev/sg0
cat: /dev/sg0: Permission denied

but maybe some distro decided that everybody should have direct device access..

Jann?

Linus