From: guido@trentalancia.com (Guido Trentalancia)
Date: Wed, 02 Mar 2011 20:47:57 +0100
Subject: [refpolicy] [PATCH 32/34]: patch to allow mount use kernel file
 descriptors
In-Reply-To: <4D6E9579.1050105@redhat.com>
References: <1297838523.3205.120.camel@tesla.lan>
	<4D6BB9CC.7060406@tresys.com> <1298920576.3123.12.camel@tesla.lan>
	<4D6D44C0.5090700@tresys.com> <1299013715.14035.52.camel@tesla.lan>
	<4D6E9579.1050105@redhat.com>
Message-ID: <1299095277.28492.13.camel@tesla.lan>
To: refpolicy@oss.tresys.com
List-Id: refpolicy.oss.tresys.com

On Wed, 02/03/2011 at 14.07 -0500, Daniel J Walsh wrote:
> On 03/01/2011 04:08 PM, Guido Trentalancia wrote:
> > On Tue, 01/03/2011 at 14.10 -0500, Christopher J. PeBenito wrote:
> >> On 02/28/11 14:16, Guido Trentalancia wrote:
> >>> On Mon, 28/02/2011 at 10.05 -0500, Christopher J. PeBenito wrote:
> >>>> On 02/16/11 01:42, Guido Trentalancia wrote:
> >>>>> This patch allows mount to use kernel file descriptors.
> >>>>>
> >>>>> diff -pruN refpolicy-git-15022011-test/policy/modules/system/mount.te refpolicy-git-15022011-test-new/policy/modules/system/mount.te
> >>>>> --- refpolicy-git-15022011-test/policy/modules/system/mount.te	2011-02-16 02:34:33.253189215 +0100
> >>>>> +++ refpolicy-git-15022011-test-new/policy/modules/system/mount.te	2011-02-16 03:54:18.732023725 +0100
> >>>>> @@ -51,6 +51,7 @@ can_exec(mount_t, mount_exec_t)
> >>>>>  
> >>>>>  files_tmp_filetrans(mount_t, mount_tmp_t, { file dir })
> >>>>>  
> >>>>> +kernel_use_fds(mount_t)
> >>>>>  kernel_read_system_state(mount_t)
> >>>>>  kernel_read_kernel_sysctls(mount_t)
> >>>>>  kernel_dontaudit_getattr_core_if(mount_t)
> >>>>
> >>>> How did you come across this?
> >>>
> >>> type=1400 audit(1295758153.958:3): avc:  denied  { use } for  pid=1429
> >>> comm="mount" path="/dev/pts/0" dev=devpts ino=3
> >>> scontext=system_u:system_r:mount_t:s0
> >>> tcontext=system_u:system_r:kernel_t:s0 tclass=fd
> >>
> >> Can you provide more detail?  What was happening on the system?
> > 
> > Unfortunately I cannot provide more details now. I believe it's
> > happening at boot-up. I am also quite sure it's not critical. And the
> > only "uncommon" thing that I am using is the /sbin/mount.tmpfs script
> > from Fedora (will be obsoleted soon by the way).
> > 
> > You could just drop it for the time being...
> > 
> > Regards,
> > 
> > Guido
> > 
> > _______________________________________________
> > refpolicy mailing list
> > refpolicy at oss.tresys.com
> > http://oss.tresys.com/mailman/listinfo/refpolicy
> 
> I would guess kernel_t opens the /dev/pts/0 file descriptor to stdout
> passes it to init, which passes it to initrc_t which passes it to
> mount_t.  (init_t could pass it directly to mount_t).

And mount_t uses it to print out messages such as "mount
point /proc/bus/usb does not exist" very early during boot-up. Does this
sound like a possible end of the story ?

Regards,

Guido