From: cpebenito@tresys.com (Christopher J. PeBenito)
Date: Tue, 5 Jan 2016 13:38:37 -0500
Subject: [refpolicy] [PATCH 1/3] Label Xorg server binary correctly on
 Arch Linux
In-Reply-To: <1450625330-21892-1-git-send-email-nicolas.iooss@m4x.org>
References: <1450625330-21892-1-git-send-email-nicolas.iooss@m4x.org>
Message-ID: <568C0DAD.3050508@tresys.com>
To: refpolicy@oss.tresys.com
List-Id: refpolicy.oss.tresys.com

On 12/20/2015 10:28 AM, Nicolas Iooss wrote:
> On Arch Linux, /usr/bin/Xorg is only a shell script which executes
> /usr/lib/xorg-server/Xorg.wrap, which is a SUID binary wrapper around
> /usr/lib/xorg-server/Xorg.
> 
> Even though Xorg.wrap is not a full X server, it reads X11 configuration
> files, uses the DRM interface to detect KMS, etc. (cf.
> http://cgit.freedesktop.org/xorg/xserver/tree/hw/xfree86/xorg-wrapper.c?id=xorg-server-1.18.0
> for more details).  Therefore label it as xserver_exec_t.
> 
> This makes the following AVC appear:
> 
>     denied  { execute_no_trans } for  pid=927 comm="X"
>     path="/usr/lib/xorg-server/Xorg.wrap" dev="dm-0" ino=3152592
>     scontext=system_u:system_r:xserver_t
>     tcontext=system_u:object_r:xserver_exec_t tclass=file
> 
> Allow /usr/bin/Xorg to execute Xorg.wrap with a can_exec statement.
> ---
>  policy/modules/services/xserver.fc | 2 ++
>  policy/modules/services/xserver.te | 3 +++
>  2 files changed, 5 insertions(+)
> 
> diff --git a/policy/modules/services/xserver.fc b/policy/modules/services/xserver.fc
> index 71b307c2fbea..397993fb4944 100644
> --- a/policy/modules/services/xserver.fc
> +++ b/policy/modules/services/xserver.fc
> @@ -70,6 +70,8 @@ HOME_DIR/\.Xauthority.*	--	gen_context(system_u:object_r:xauth_home_t,s0)
>  /usr/bin/Xorg		--	gen_context(system_u:object_r:xserver_exec_t,s0)
>  
>  /usr/lib/qt-.*/etc/settings(/.*)? gen_context(system_u:object_r:xdm_var_run_t,s0)
> +/usr/lib/xorg-server/Xorg	--	gen_context(system_u:object_r:xserver_exec_t,s0)
> +/usr/lib/xorg-server/Xorg\.wrap	--	gen_context(system_u:object_r:xserver_exec_t,s0)
>  
>  /usr/sbin/lightdm	--	gen_context(system_u:object_r:xdm_exec_t,s0)
>  
> diff --git a/policy/modules/services/xserver.te b/policy/modules/services/xserver.te
> index 2ba7a7415e2a..8dc7c83e491c 100644
> --- a/policy/modules/services/xserver.te
> +++ b/policy/modules/services/xserver.te
> @@ -827,6 +827,9 @@ manage_sock_files_pattern(xserver_t, xdm_tmp_t, xdm_tmp_t)
>  allow xserver_t xkb_var_lib_t:lnk_file read;
>  can_exec(xserver_t, xkb_var_lib_t)
>  
> +# Run Xorg.wrap
> +can_exec(xserver_t, xserver_exec_t)
> +
>  # VNC v4 module in X server
>  corenet_tcp_bind_vnc_port(xserver_t)

Merged.

-- 
Chris PeBenito
Tresys Technology, LLC
www.tresys.com | oss.tresys.com