From: Andy Lutomirski <luto@amacapital.net>
To: Colin Walters <walters@verbum.org>
Cc: Casey Schaufler <casey@schaufler-ca.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Jamie Lokier <jamie@shareable.org>,
Will Drewry <wad@chromium.org>,
linux-kernel@vger.kernel.org, keescook@chromium.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 v2 0/4] PR_SET_NO_NEW_PRIVS, unshare, and chroot
Date: Mon, 16 Jan 2012 13:25:42 -0800 [thread overview]
Message-ID: <CALCETrW3WyzaGBMJZzfohD=MRwdmeV9bAo4Leg1gaSnPL5URpg@mail.gmail.com> (raw)
In-Reply-To: <1326746949.3467.16.camel@lenny>
On Mon, Jan 16, 2012 at 12:49 PM, Colin Walters <walters@verbum.org> wrote:
> On Sun, 2012-01-15 at 16:37 -0800, Andy Lutomirski wrote:
>> To make the no_new_privs discussion more concrete, here is an updated
>> series that is actually useful. It adds PR_SET_NO_NEW_PRIVS
>
> I think it'd be clearer to call it PR_SET_NOSUID - basically it should
> match the semantics for MS_NOSUID mounts, as if on every exec()
> thereafter the target binary was on a nosuid filesystem.
The MS_NOSUID semantics are somewhat ridiculous for selinux, and I'd
rather not make them match for no_new_privs. AppArmor completely
ignores MS_NOSUID, so I think the rename would just cause more
confusion.
>
> You might then change this flag to only take effect on a later exec(),
> which would solve your race condition for the hypothetical PAM module.
That would just make it more complicated. The race is already solved
in the current patch, anyway.
>
>> with the
>> same semantics as before (plus John Johansen's AppArmor fix and with
>> improved bisectability). It then allows some unshare flags
>
> What's the rationale behind the unshare subset? Did you actually
> analyze any setuid binaries found on Debian/Fedora etc. and determined
> that e.g. CLONE_NEWNET was problematic for some reason?
CLONE_NEWNET seems more likely to consume significant kernel resources
than the others. I didn't have a great reason, though. Unsharing the
filesystem namespace is possibly dangerous because it could prevent an
unmount in the original namespace from taking effect everywhere.
>
> I actually want CLONE_NEWNET for my build tool, so I can be sure the
> arbitrary code I'm executing as part of the build at least isn't
> downloading more new code.
>
>
Fair enough. I may add this in v3. seccomp is an even better
solution, though :)
--Andy
next prev parent reply other threads:[~2012-01-16 21:26 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-16 0:37 [PATCH v2 0/4] PR_SET_NO_NEW_PRIVS, unshare, and chroot Andy Lutomirski
2012-01-16 0:37 ` [PATCH v2 1/4] Add PR_{GET,SET}_NO_NEW_PRIVS to prevent execve from granting privs Andy Lutomirski
2012-01-16 17:33 ` Oleg Nesterov
2012-01-16 20:15 ` Andy Lutomirski
2012-01-16 0:37 ` [PATCH v2 2/4] Fix apparmor for PR_{GET,SET}_NO_NEW_PRIVS Andy Lutomirski
2012-01-16 0:37 ` [PATCH v2 3/4] Allow unprivileged CLONE_NEWUTS and CLONE_NEWIPC with no_new_privs Andy Lutomirski
2012-01-16 0:37 ` [PATCH 4/4] Allow unprivileged chroot when safe Andy Lutomirski
2012-01-16 0:45 ` Linus Torvalds
2012-01-16 1:08 ` Andy Lutomirski
2012-01-16 19:26 ` Colin Walters
2012-01-16 20:18 ` Andy Lutomirski
2012-01-17 10:14 ` Jamie Lokier
2012-01-16 20:06 ` Al Viro
2012-01-16 20:15 ` Andy Lutomirski
2012-01-16 20:26 ` Al Viro
2012-01-17 16:23 ` Oleg Nesterov
2012-01-17 16:31 ` Andy Lutomirski
2012-01-16 1:04 ` [PATCH v2 0/4] PR_SET_NO_NEW_PRIVS, unshare, and chroot Andy Lutomirski
2012-01-16 20:49 ` Colin Walters
2012-01-16 21:25 ` Andy Lutomirski [this message]
2012-01-16 21:47 ` Colin Walters
2012-01-16 21:57 ` Andy Lutomirski
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