From: Cyrill Gorcunov <gorcunov@gmail.com>
To: linux-kernel@vger.kernel.org
Cc: Kees Cook <keescook@chromium.org>, Tejun Heo <tj@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Andrew Vagin <avagin@openvz.org>,
"Eric W. Biederman" <ebiederm@xmission.com>,
Serge Hallyn <serge.hallyn@canonical.com>,
Pavel Emelyanov <xemul@parallels.com>,
Vasiliy Kulikov <segoon@openwall.com>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
Michael Kerrisk <mtk.manpages@gmail.com>
Subject: Re: [RFC 2/2] prctl: PR_SET_MM -- Introduce PR_SET_MM_MAP operation
Date: Tue, 8 Jul 2014 23:08:49 +0400 [thread overview]
Message-ID: <20140708190849.GC17860@moon.sw.swsoft.com> (raw)
In-Reply-To: <20140703151102.842945837@openvz.org>
On Thu, Jul 03, 2014 at 06:33:20PM +0400, Cyrill Gorcunov wrote:
> During development of c/r we've noticed that in case if we need to
> support user namespaces we face a problem with capabilities in
> prctl(PR_SET_MM, ...) call.
>
> Current PR_SET_MM code forbids to modify fields if no CAP_SYS_RESOURCE
> granted, but rather relies on one who use this interface is passing
> more-less sane values (though the values must pass the basic validation
> procedure).
>
> It seems a better approach is to eliminate CAP_SYS_RESOURCE check but
> provide all new values in one bundle, which would allow the kernel to make
> more intensive test for sanity of values and same time allow us to
> support checkpoint/restore of user namespaces.
>
> Thus a new command (PR_SET_MM_MAP) introduced. It takes a pointer of
> prctl_mm_map structure which carries all members to be updated.
>
> Most intensive work is done in validate_prctl_map_locked helper,
> because we need to make sure the values are valid. Thus we do
>
> - check the values are laying inside available user address space
> - stack, brk, command line arguments and evnironment variables
> must point to already existing VMA
> - values must be ordered (start < end)
> - if RLIMITs are defined don't allow to exceed it with new values
>
> Since it uses prctl_set_mm_exe_file_locked helper, updating the
> exe-file link is one-shot action for security reason.
>
> I believe the old interface should be deprecated and ripped off
> in a couple of kernel releases if noone against.
>
> To test if new interface is implemented in the kernel one
> can pass PR_SET_MM_MAP_SIZE opcode and the kernel returns
> the size of currently supported struct prctl_mm_map.
>
> Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
> Cc: Kees Cook <keescook@chromium.org>
> Cc: Tejun Heo <tj@kernel.org>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Andrew Vagin <avagin@openvz.org>
> Cc: Eric W. Biederman <ebiederm@xmission.com>
> Cc: Serge Hallyn <serge.hallyn@canonical.com>
> Cc: Pavel Emelyanov <xemul@parallels.com>
> Cc: Vasiliy Kulikov <segoon@openwall.com>
> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Ping. Guys, any commens please?
next prev parent reply other threads:[~2014-07-08 19:11 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-07-03 14:33 [RFC 0/2] prctl: set-mm -- Rework interface Cyrill Gorcunov
2014-07-03 14:33 ` [RFC 1/2] prctl: PR_SET_MM -- Factor out mmap_sem when update mm::exe_file Cyrill Gorcunov
2014-07-03 14:33 ` [RFC 2/2] prctl: PR_SET_MM -- Introduce PR_SET_MM_MAP operation Cyrill Gorcunov
2014-07-03 20:34 ` Cyrill Gorcunov
2014-07-04 7:52 ` Andrew Vagin
2014-07-04 8:11 ` Cyrill Gorcunov
2014-07-08 19:08 ` Cyrill Gorcunov [this message]
2014-07-08 21:38 ` Andrew Morton
2014-07-08 22:13 ` Cyrill Gorcunov
2014-07-09 14:13 ` Cyrill Gorcunov
2014-07-09 14:53 ` Kees Cook
2014-07-09 15:06 ` Cyrill Gorcunov
2014-07-11 17:36 ` Cyrill Gorcunov
2014-07-22 20:07 ` Kees Cook
2014-07-22 20:36 ` Cyrill Gorcunov
2014-07-24 13:48 ` Andrew Vagin
2014-07-24 16:42 ` Cyrill Gorcunov
2014-07-24 18:44 ` Kees Cook
2014-07-24 18:50 ` Cyrill Gorcunov
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