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From:   Russell Coker <russell@coker.com.au>
To:     Dominick Grift <dominick.grift@defensec.nl>
Cc:     selinux-refpolicy@vger.kernel.org
Subject: Re: machinectl shell policy
Date:   Fri, 25 Dec 2020 20:16:07 +1100
Message-ID: <5735537.jZnottUgFY@liv>
In-Reply-To: <ypjl8s9m5nbi.fsf@defensec.nl>
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On Friday, 25 December 2020 6:58:41 PM AEDT Dominick Grift wrote:
> Russell Coker <russell@coker.com.au> writes:
> > On Thursday, 24 December 2020 7:37:50 PM AEDT Dominick Grift wrote:
> >> > To enable "machinectl shell" on recent versions of systemd we need
> >> > something like the above policy (which is not complete or ideal, still
> >> > doesn't work so no point polishing it) and something for the below. 
> >> > What
> >> > is the below about?
> >> 
> >> this should be thoroughly addressed. machined creates a login pty that
> >> gets relabeled on login as per type_change rules.
> > 
> > Currently it's not being relabeled on Debian, but that's a separate issue.
> 
> Maybe the required type_change rules arent present?

Here is all the policy to make it work.  Maybe we should have a type like 
system_dbusd_devpts_t for this.  This is not policy for inclusion, this is 
policy to discuss before writing that policy.

term_user_pty(user_systemd_t, user_devpts_t)
term_login_pty(devpts_t)
allow user_systemd_t user_devpts_t:chr_file rw_file_perms;

# for machinectl shell
allow sysadm_t systemd_machined_t:dbus send_msg;
systemd_manage_userdb_runtime_dirs(systemd_machined_t)
systemd_manage_userdb_runtime_sock_files(systemd_machined_t)
term_use_ptmx(systemd_machined_t)
dev_getattr_fs(systemd_machined_t)
term_getattr_pty_fs(systemd_machined_t)
allow systemd_machined_t sysadm_t:dbus send_msg;
allow systemd_machined_t devpts_t:chr_file rw_file_perms;
allow system_dbusd_t systemd_machined_t:fd use;
allow system_dbusd_t devpts_t:chr_file { read write };
allow system_dbusd_t ptmx_t:chr_file { read write };
allow sysadm_t systemd_machined_t:fd use;
allow user_systemd_t shell_exec_t:file entrypoint;
allow user_systemd_t systemd_machined_t:fd use;
allow user_systemd_t self:process signal; 
allow user_t systemd_machined_t:fd use;
allow user_t user_systemd_t:fifo_file { getattr write };
allow user_t init_t:process signal;

> > https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=892001
> > 
> > We have work in progress on dbus-broker in Debian.  Would it make sense to
> > only support dbus-broker in SE Linux policy?  Being forced to use only 1
> > of
> > the 2 dbus programs (and the newer and faster 1 of the 2) is a very small
> > trade-off, smaller than some of the other trade-offs for running SE Linux.
> 
> should probably be able to support both (conditionally) but could get messy

Currently we have a heap of ifdef systemd in the policy, as probably the only 
people not wanting dbus-broker will be the ones not wanting systemd we could 
include it in the same ifdef rules.

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