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Message-ID: <alpine.LRH.2.21.1809280744560.8410@namei.org>
Date: Fri, 28 Sep 2018 07:45:00 +1000 (AEST)
From: James Morris <jmorris@...ei.org>
To: Casey Schaufler <casey.schaufler@...el.com>
cc: kernel-hardening@...ts.openwall.com, linux-kernel@...r.kernel.org,
linux-security-module@...r.kernel.org, selinux@...ho.nsa.gov,
dave.hansen@...el.com, deneen.t.dock@...el.com,
kristen@...ux.intel.com, arjan@...ux.intel.com
Subject: Re: [PATCH v5 5/5] sidechannel: Linux Security Module for
sidechannel
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.
It least make it user configurable.
--
James Morris
<jmorris@...ei.org>
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