Re: [Xen-devel] XSM: new set of "avc denied"

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

On Mon, 2015-05-25 at 10:40 +0100, Wei Liu wrote:
> I had a look at Osstest's latest xen-unstable run [0]. With Ian's patch
> series we finally passed the point of guest creation on x86.
> 
> We now have a new set of "avc denied".

Thanks for picking up on these, I was just about to.

> May 24 20:18:05.945118 (XEN) avc:  denied  { get_vnumainfo } for domid=1 
> scontext=system_u:system_r:domU_t tcontext=system_u:system_r:domU_t_self 
> tclass=domain2
> 
> This is HVM loader trying to call get_vnumainfo
> 
> May 24 20:28:50.593013 (XEN) avc:  denied  { logdirty } for domid=0 target=3 
> scontext=system_u:system_r:dom0_t tcontext=system_u:system_r:domU_t 
> tclass=shadow
> May 24 20:29:20.721085 (XEN) avc:  denied  { disable } for domid=0 target=3 
> scontext=system_u:system_r:dom0_t tcontext=system_u:system_r:domU_t 
> tclass=shadow
> May 24 20:29:20.737023 (XEN) avc:  denied  { disable } for domid=0 target=3 
> scontext=system_u:system_r:dom0_t tcontext=system_u:system_r:domU_t 
> tclass=shadow
> 
> The above failures made guest local migration test fail for both PV and HVM
> guests.

Yes, this seems to be the biggest cause of failures

> May 24 14:36:47.541016 (XEN) avc:  denied  { writeconsole } for domid=1 
> scontext=system_u:system_r:domU_t tcontext=system_u:system_r:xen_t tclass=xen
> 
> This is PV specific, I think it was due to PV guest was configured to write to
> console and XSM (rightfully?) rejected that.

I think this is from the use of xen_raw_console_write early on in the
Linux pvops kernel.

By default these would be nop on a debug=n hypervisor, and they are
controllable with the guest_loglvl hypervisor option in both debug
cases, I think.

I think XSM rejecting is valid, but I'd also be happy with a change to
allow it and rely on the handling via the console options as folks like.

Ian.

>  My guess is that HVM is not
> configured to write to console so I don't see that in HVM test cases.


Correct, although I would expect hvmloader to have been even more
chatty, guess I am wrong about that.

FWIW I saw quite a few of these from the stubdom mini-os when I tested
stub-dm as well.

Ian.



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