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From: Cyrill Gorcunov <gorcunov@gmail.com>
To: Kees Cook <keescook@chromium.org>
Cc: Davidlohr Bueso <dave@stgolabs.net>,
	Oleg Nesterov <oleg@redhat.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Al Viro <viro@zeniv.linux.org.uk>,
	koct9i@gmail.com, Linux-MM <linux-mm@kvack.org>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH -next v2 0/4] mm: replace mmap_sem for mm->exe_file serialization
Date: Fri, 20 Mar 2015 19:09:10 +0300	[thread overview]
Message-ID: <20150320160910.GA27066@moon> (raw)
In-Reply-To: <CAGXu5j+S1iw6VCjqfS_sPTOjNz8XAy0kkFD7dTvvTTgagx-PMA@mail.gmail.com>

On Mon, Mar 16, 2015 at 03:08:40PM -0700, Kees Cook wrote:
> >
> >> Ok I think I am finally seeing where you are going. And I like it *a
> >> lot* because it allows us to basically replace mmap_sem with rcu
> >> (MMF_EXE_FILE_CHANGED being the only user that requires a lock!!), but
> >> am afraid it might not be possible. I mean currently we have no rule wrt
> >> to users that don't deal with prctl.
> >>
> >> Forbidding multiple exe_file changes to be generic would certainly
> >> change address space semantics, probably for the better (tighter around
> >> security), but changed nonetheless so users would have a right to
> >> complain, no? So if we can get away with removing MMF_EXE_FILE_CHANGED
> >> I'm all for it. Andrew?
> 
> I can't figure out why MMF_EXE_FILE_CHANGED is used to stop a second
> change. But it does seem useful to mark a process as "hey, we know for
> sure this the exe_file changed on this process" from an accounting
> perspective.

Sure, except it start being more stopper for further development so
ripping it off would help ;)

> 
> And I'd agree about the malware: it would never use this interface, so
> there's no security benefit I can see. Maybe I haven't had enough
> coffee, though. :)

Yes, same here, would never use it either.

      reply	other threads:[~2015-03-20 16:09 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-03-14 22:39 Davidlohr Bueso
2015-03-14 22:39 ` [PATCH 1/4] " Davidlohr Bueso
2015-03-14 22:39 ` [PATCH 2/4] mm: introduce struct exe_file Davidlohr Bueso
2015-03-14 22:39 ` [PATCH 3/4] prctl: move MMF_EXE_FILE_CHANGED into exe_file struct Davidlohr Bueso
2015-03-15  2:13   ` Davidlohr Bueso
2015-03-14 22:39 ` [PATCH 4/4] kernel/fork: use pr_alert() for rss counter bugs Davidlohr Bueso
2015-03-16 11:30   ` Konstantin Khlebnikov
2015-03-15 14:21 ` [PATCH -next v2 0/4] mm: replace mmap_sem for mm->exe_file serialization Oleg Nesterov
2015-03-15 14:54   ` Davidlohr Bueso
2015-03-15 15:26     ` Oleg Nesterov
2015-03-15 15:42       ` Davidlohr Bueso
2015-03-15 17:05         ` Cyrill Gorcunov
2015-03-15 17:34           ` Davidlohr Bueso
2015-03-16 22:08           ` Kees Cook
2015-03-20 16:09             ` Cyrill Gorcunov [this message]

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