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Date: Fri, 28 Sep 2018 08:47:13 +1000 (AEST)
From: James Morris <jmorris@...ei.org>
To: Casey Schaufler <casey@...aufler-ca.com>
cc: Casey Schaufler <casey.schaufler@...el.com>, kristen@...ux.intel.com,
kernel-hardening@...ts.openwall.com, deneen.t.dock@...el.com,
linux-kernel@...r.kernel.org, dave.hansen@...el.com,
linux-security-module@...r.kernel.org, selinux@...ho.nsa.gov,
arjan@...ux.intel.com
Subject: Re: [PATCH v5 5/5] sidechannel: Linux Security Module for
sidechannel
On Thu, 27 Sep 2018, Casey Schaufler wrote:
> On 9/27/2018 2:45 PM, James Morris wrote:
> > On Wed, 26 Sep 2018, Casey Schaufler wrote:
> >
> >> + /*
> >> + * Namespace checks. Considered safe if:
> >> + * cgroup namespace is the same
> >> + * User namespace is the same
> >> + * PID namespace is the same
> >> + */
> >> + if (current->nsproxy)
> >> + ccgn = current->nsproxy->cgroup_ns;
> >> + if (p->nsproxy)
> >> + pcgn = p->nsproxy->cgroup_ns;
> >> + if (ccgn != pcgn)
> >> + return -EACCES;
> >> + if (current->cred->user_ns != p->cred->user_ns)
> >> + return -EACCES;
> >> + if (task_active_pid_ns(current) != task_active_pid_ns(p))
> >> + return -EACCES;
> >> + return 0;
> > I really don't like the idea of hard-coding namespace security semantics
> > in an LSM. Also, I'm not sure if these semantics make any sense.
>
> Checks on namespaces where explicitly requested.
By whom and what is the rationale?
--
James Morris
<jmorris@...ei.org>
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