Message-ID: <4D657E0C.3010102@schaufler-ca.com>
Date: Wed, 23 Feb 2011 13:37:16 -0800
From: Casey Schaufler <casey@schaufler-ca.com>
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To: "Eric W. Biederman" <ebiederm@xmission.com>
CC: "Serge E. Hallyn" <serge.hallyn@canonical.com>,
        David Howells <dhowells@redhat.com>,
        LSM <linux-security-module@vger.kernel.org>,
        Andrew Morton <akpm@osdl.org>, James Morris <jmorris@namei.org>,
        Kees Cook <kees.cook@canonical.com>,
        containers@lists.linux-foundation.org,
        kernel list <linux-kernel@vger.kernel.org>,
        Alexey Dobriyan <adobriyan@gmail.com>,
        Michael Kerrisk <mtk.manpages@gmail.com>, xemul@parallels.com,
        Casey Schaufler <casey@schaufler-ca.com>
Subject: Re: User namespaces and keys
References: <20110223135814.GA1859@mail.hallyn.com>	<20110217150224.GA26334@mail.hallyn.com> <29677.1298462729@redhat.com>	<890.1298473574@redhat.com> <m162sasqj6.fsf@fess.ebiederm.org>	<20110223155328.GA21266@peq.hallyn.com>	<4D655EE4.6030707@schaufler-ca.com> <m1k4gqlbdm.fsf@fess.ebiederm.org>
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On 2/23/2011 12:55 PM, Eric W. Biederman wrote:
> Casey Schaufler <casey@schaufler-ca.com> writes:
>
>> I confess that I remain less well educated on namespaces than
>> I probably should be, but with what I do know it seems that the
>> relationships between user namespaces and LSMs are bound to be
>> strained from the beginning. Some LSMs (SELinux and Smack) are
>> providing similar sandbox capabilities to what you get from user
>> namespaces, but from different directions and with different
>> use cases.
> Casey I won't argue about the possibility of things being strained, but
> I think if we focus on the semantics and not on the end goal of exactly
> how the pieces are to be used there can be some reasonable dialog.

I'm sure that there will be cases where they will work together
like horses in a troika. Making sensible semantics for the interactions
is key, and it is entirely possible that in some cases a comparison
of semantics and behaviors will lead an end user to chose either an
LSM or namespaces over the combination. Just like I expect that even
when we allow multiple LSMs the SELinux and Smack combination will be
rare among the sane.

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