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

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Date:   Fri, 6 Jul 2018 19:39:25 -0700
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     James Bottomley <James.Bottomley@...senpartnership.com>,
        Jann Horn <jannh@...gle.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Linux SCSI List <linux-scsi@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [GIT PULL] SCSI fixes for 4.18-rc3

On Fri, Jul 6, 2018 at 7:31 PM Linus Torvalds
<torvalds@...ux-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