linux-kernel - Re: kdbus_proc_permission (Re: [GIT PULL] kdbus updates for Greg)

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Message-ID: <CA+5PVA6K6yRxCKfANQz2b_81Rn-9_3zdNxKfc-vt5Su04L7DhA@mail.gmail.com>
Date:	Tue, 1 Sep 2015 13:13:24 -0400
From:	Josh Boyer <jwboyer@...oraproject.org>
To:	Andy Lutomirski <luto@...capital.net>
Cc:	David Herrmann <dh.herrmann@...il.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Greg KH <gregkh@...uxfoundation.org>
Subject: Re: kdbus_proc_permission (Re: [GIT PULL] kdbus updates for Greg)

On Mon, Aug 31, 2015 at 3:09 PM, Andy Lutomirski <luto@...capital.net> wrote:
> On Mon, Aug 31, 2015 at 9:22 AM, David Herrmann <dh.herrmann@...il.com> wrote:
>> Hi
>>
>> On Mon, Aug 31, 2015 at 5:37 PM, Andy Lutomirski <luto@...capital.net> wrote:
>>> On Mon, Aug 24, 2015 at 2:52 AM, David Herrmann <dh.herrmann@...il.com> wrote:
>>>> On Mon, Aug 10, 2015 at 4:42 AM, Andy Lutomirski <luto@...capital.net> wrote:
>>>>> I haven't checked the context in which it's used, but in order for
>>>>> kdbus_proc_permission to do what it claims to do, it appears to be
>>>>> missing calls to security_inode_permission and
>>>>> security_file_permission.
>>>>
>>>> Both are expected to be added by lsm patches (both hooks you mentioned
>>>> are empty if no lsm is selected).
>>>
>>> Will that mean that existing MAC policies stop being fully enforced
>>> (in effect) if kdbus is installed?
>>
>> It means kdbus messages carry information about the sender, which LSMs
>> might prevent you to read via /proc. Just like you can send dbus
>> messages to a peer, which LSM-enhanced dbus-daemon might not allow.
>
> It's a security-sensitive function that doesn't do what the name and
> description suggest.  Whether that's an active problem or not is
> unknown, but it's certainly a maintainability problem.
>
>> If
>> you use LSMs, we clearly advise you to wait for kdbus to gain LSM
>> support. We explicitly support legacy dbus1-compat for exactly such
>> reasons.
>
> This is not an acceptable attitude for security.
>
> There are so many things wrong with your statement that I'll limit
> myself to one of them: Fedora 23/Rawhide, which is the *reference*
> platform, uses SELinux.

Clarification: Fedora Rawhide only.  The kdbus code is not included in
the F23 kernel.

Your point otherwise stands.  I just don't want Phoronix or someone
else getting confused and thinking Fedora 23 will ship with kdbus.  It
will not.

josh
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