Re: [RFC][PATCHES] iov_iter.c rewrite

From: Dave Jones
Date: Mon Dec 08 2014 - 17:31:34 EST

On Mon, Dec 08, 2014 at 02:23:06PM -0800, Linus Torvalds wrote:
> On Mon, Dec 8, 2014 at 2:14 PM, Theodore Ts'o <tytso@xxxxxxx> wrote:
> >
> > running trinity as root should be quite safe in a VM. :-)
> It's not so much the safety that I'd worry about, it's the "you can
> legitimately just reboot it or cause kernel corruption as root". You
> may not cause any problems outside of the VM, but any oopses inside
> the VM might be due to trinity just doing bad things as root, rather
> than kernel bugs..
> Of course, it's probably hard to hit things like laoding random
> modules etc, since even without signature requirements there are tons
> of ELF sanity checks and other things. So it might be hard to actually
> do those kinds of "corrupt kernel memory as root" things with trinity.

It also goes out of its way to avoid doing obviously stupid things,
like using /dev/mem as an fd, plus a whole bunch of similar sysfs/procfs
knobs. There are still likely a whole bunch of similar things that
might have horrible effects too. It's been on my todo for a while to
revisit that particular case and blacklist a bunch of other things.

And then there's obviously "don't do this syscall, ever" or "with these
args" type things, which could use expanding.. It's a big effort tbh.
I'm amazed that Sasha, Kirill and everyone else running it as root in
vm's aren't buried alive in false-positives.


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