Re: [Xen-devel] [PATCH] xsm: correct AVC lookups for two sysctls

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 09/08/17 17:56, Daniel De Graaf wrote:
> The current code was incorrectly using SECCLASS_XEN instead of
> SECCLASS_XEN2, resulting in the wrong permission being checked.
>
> GET_CPU_LEVELLING_CAPS was checking MTRR_DEL
> GET_CPU_FEATURESET was checking MTRR_READ
>
> The default XSM policy only allowed these permissions to dom0, so this
> didn't result in a security issue there.
>
> Signed-off-by: Daniel De Graaf <dgdegra@xxxxxxxxxxxxx>

Oops - This looks like my fault.  Sorry.

Acked-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

> ---
>  xen/xsm/flask/hooks.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/xen/xsm/flask/hooks.c b/xen/xsm/flask/hooks.c
> index 819e25d3af..57be18d6d4 100644
> --- a/xen/xsm/flask/hooks.c
> +++ b/xen/xsm/flask/hooks.c
> @@ -814,10 +814,12 @@ static int flask_sysctl(int cmd)
>          return domain_has_xen(current->domain, XEN__TMEM_CONTROL);
>  
>      case XEN_SYSCTL_get_cpu_levelling_caps:
> -        return domain_has_xen(current->domain, XEN2__GET_CPU_LEVELLING_CAPS);
> +        return avc_current_has_perm(SECINITSID_XEN, SECCLASS_XEN2,
> +                                    XEN2__GET_CPU_LEVELLING_CAPS);
>  
>      case XEN_SYSCTL_get_cpu_featureset:
> -        return domain_has_xen(current->domain, XEN2__GET_CPU_FEATURESET);
> +        return avc_current_has_perm(SECINITSID_XEN, SECCLASS_XEN2,
> +                                    XEN2__GET_CPU_FEATURESET);
>  
>      case XEN_SYSCTL_livepatch_op:
>          return avc_current_has_perm(SECINITSID_XEN, SECCLASS_XEN2,


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