netdev - Re: [PATCH 3/3] selinux: Add SELinux GTP support

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Date:   Wed, 30 Sep 2020 13:01:53 +0200
From:   Harald Welte <laforge@...monks.org>
To:     Richard Haines <richard_c_haines@...nternet.com>
Cc:     selinux@...r.kernel.org, linux-security-module@...r.kernel.org,
        osmocom-net-gprs@...ts.osmocom.org, netdev@...r.kernel.org,
        stephen.smalley.work@...il.com, paul@...l-moore.com,
        pablo@...filter.org, jmorris@...ei.org
Subject: Re: [PATCH 3/3] selinux: Add SELinux GTP support

Hi Richard,

I don't fully understand in which context you need / use those SELinux GTP hooks,
however one comment from the point of view of somebody who is working on GGSN/P-GW
software using the GTP kernel module:

On Wed, Sep 30, 2020 at 10:49:34AM +0100, Richard Haines wrote:
> +selinux_gtp_dev_cmd()
> +~~~~~~~~~~~~~~~~~~~~~
> +Validate if the caller (current SID) and the GTP device SID have the required
> +permission to perform the operation. The GTP/SELinux permission map is
> +as follow::
> +
> +    GTP_CMD_NEWPDP = gtp { add }
> +    GTP_CMD_DELPDP = gtp { del }
> +    GTP_CMD_GETPDP = gtp { get }

Wouldn't it make sense to differentiate between:

a) add/del/get on the GTP netdev
b) add/del/get on the indivudual PDP wihin the GTP netdev

'a' is typically only created once at startup of a GGSN/P-GW software, or is
done even at system stat-up time.

'b' is performed frequently during runtime as the GGSN/P-GW function runs, as
subscribers attach to / detach from the cellular network.

By differentiating between those two, one could further constrain the permissions
required at runtime.

-- 
- Harald Welte <laforge@...monks.org>           http://laforge.gnumonks.org/
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