From: Kees Cook <keescook@chromium.org>
To: Andrew Lutomirski <luto@mit.edu>
Cc: Will Drewry <wad@chromium.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
linux-kernel@vger.kernel.org, john.johansen@canonical.com,
serge.hallyn@canonical.com, coreyb@linux.vnet.ibm.com,
pmoore@redhat.com, eparis@redhat.com, djm@mindrot.org,
segoon@openwall.com, rostedt@goodmis.org, jmorris@namei.org,
scarybeasts@gmail.com, avi@redhat.com, penberg@cs.helsinki.fi,
viro@zeniv.linux.org.uk, mingo@elte.hu,
akpm@linux-foundation.org, khilman@ti.com,
borislav.petkov@amd.com, amwang@redhat.com, oleg@redhat.com,
ak@linux.intel.com, eric.dumazet@gmail.com, gregkh@suse.de,
dhowells@redhat.com, daniel.lezcano@free.fr,
linux-fsdevel@vger.kernel.org,
linux-security-module@vger.kernel.org, olofj@chromium.org,
mhalcrow@google.com, dlaor@redhat.com, corbet@lwn.net,
alan@lxorguk.ukuu.org.uk
Subject: Re: [PATCH PLACEHOLDER 1/3] fs/exec: "always_unprivileged" patch
Date: Thu, 12 Jan 2012 18:09:38 -0800 [thread overview]
Message-ID: <CAGXu5jLwXgB=Fc=v=iZ=yH+ngwivF5mdK+5LFoS8fCqNAXHvNA@mail.gmail.com> (raw)
In-Reply-To: <CAObL_7Fr-yV33jobSa3g_WqVJar-5x5oQM0t8GJxcLFsuBhLtg@mail.gmail.com>
On Thu, Jan 12, 2012 at 5:41 PM, Andrew Lutomirski <luto@mit.edu> wrote:
> On Thu, Jan 12, 2012 at 5:37 PM, Will Drewry <wad@chromium.org> wrote:
>> On Thu, Jan 12, 2012 at 7:11 PM, Andrew Lutomirski <luto@mit.edu> wrote:
>>> (Also, preventing dropping of privileges will probably make a patch
>>> more complicted -- I'll have to find and update all the places that
>>> allow dropping privileges.)
>>
>> An alternative approach might be that the restricted bit drops all
>> privileges that allows privilege changes in either direction. E.g.,
>> - set restricted bit
>> -- adds a check anywhere MNT_NOSUID is
>> -- sets securebit to SECURE_NOROOT|..LOCKED
>> -- drops CAP_SETUID, CAP_DAC_OVERRIDE, ...
>> -- set the caps bounding set to the minimum the restricted bit allows
>>
>> That may deviate from the intent (by re-using caps), but it could keep some
>> of the privilege transition checking code the same.
>
> I'm not sure it'll be much of a simplification. The entire patch is
> 45 lines right now :) I'll test it and send it out.
>
> FWIW, though, it breaks apparmor (intentionally). Can any of you
> either explain what *should* happen or (better) volunteer to fix it?
> It should be about three lines of code for someone who understands
> what's going on. I don't have an apparmor system, so I can't really
> test it.
I'm happy to take a look at the AppArmor breakage. What's happening
with it at the moment?
--
Kees Cook
ChromeOS Security
prev parent reply other threads:[~2012-01-13 2:09 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-12 23:38 [PATCH PLACEHOLDER 1/3] fs/exec: "always_unprivileged" patch Will Drewry
2012-01-12 23:38 ` [PATCH v3 2/3] seccomp_filters: system call filtering using BPF Will Drewry
2012-01-13 0:51 ` Randy Dunlap
2012-01-12 23:59 ` Will Drewry
2012-01-13 1:35 ` Randy Dunlap
2012-01-13 17:39 ` Eric Paris
2012-01-13 18:50 ` Will Drewry
2012-01-12 23:38 ` [PATCH v3 3/3] Documentation: prctl/seccomp_filter Will Drewry
2012-01-15 1:52 ` Randy Dunlap
2012-01-16 1:41 ` Will Drewry
2012-01-17 23:29 ` Eric Paris
2012-01-17 23:54 ` Will Drewry
2012-01-12 23:47 ` [PATCH PLACEHOLDER 1/3] fs/exec: "always_unprivileged" patch Linus Torvalds
2012-01-13 0:03 ` Will Drewry
2012-01-13 0:42 ` Andrew Lutomirski
2012-01-13 0:57 ` Linus Torvalds
2012-01-13 1:11 ` Andrew Lutomirski
2012-01-13 1:17 ` Linus Torvalds
2012-01-14 13:30 ` Jamie Lokier
2012-01-14 19:21 ` Will Drewry
2012-01-14 20:22 ` Linus Torvalds
2012-01-14 21:04 ` Andrew Lutomirski
2012-01-15 20:16 ` Casey Schaufler
2012-01-15 20:59 ` Andrew Lutomirski
2012-01-15 21:32 ` Casey Schaufler
2012-01-15 22:07 ` Andrew Lutomirski
2012-01-16 2:04 ` Will Drewry
2012-01-18 3:12 ` Eric W. Biederman
2012-01-16 2:41 ` Casey Schaufler
2012-01-16 7:45 ` Andrew Lutomirski
2012-01-16 18:02 ` Casey Schaufler
2012-01-13 1:37 ` Will Drewry
2012-01-13 1:41 ` Andrew Lutomirski
2012-01-13 2:09 ` Kees Cook [this message]
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