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From: Jan Beulich <jbeulich@suse.com>
Subject: x86: enforce proper privilege when (un)mapping pIRQ-s
(Un)mapping of IRQs, just like other RESOURCE__ADD* / RESOURCE__REMOVE*
actions (in FLASK terms) should be XSM_DM_PRIV rather than XSM_TARGET.
This in turn requires bypassing the XSM check in physdev_unmap_pirq()
for the HVM emuirq case just like is being done in physdev_map_pirq().
The primary goal security wise, however, is to no longer allow HVM
guests, by specifying their own domain ID instead of DOMID_SELF, to
enter code paths intended for PV guest and the control domains of HVM
guests only.
This is part of XSA-237.
Reported-by: HW42 <hw42@ipsumj.de>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: George Dunlap <george.dunlap@citrix.com>
--- a/xen/arch/x86/physdev.c
+++ b/xen/arch/x86/physdev.c
@@ -111,7 +111,7 @@ int physdev_map_pirq(domid_t domid, int
if ( d == NULL )
return -ESRCH;
- ret = xsm_map_domain_pirq(XSM_TARGET, d);
+ ret = xsm_map_domain_pirq(XSM_DM_PRIV, d);
if ( ret )
goto free_domain;
@@ -256,13 +256,14 @@ int physdev_map_pirq(domid_t domid, int
int physdev_unmap_pirq(domid_t domid, int pirq)
{
struct domain *d;
- int ret;
+ int ret = 0;
d = rcu_lock_domain_by_any_id(domid);
if ( d == NULL )
return -ESRCH;
- ret = xsm_unmap_domain_pirq(XSM_TARGET, d);
+ if ( domid != DOMID_SELF || !is_hvm_domain(d) || !has_pirq(d) )
+ ret = xsm_unmap_domain_pirq(XSM_DM_PRIV, d);
if ( ret )
goto free_domain;
--- a/xen/include/xsm/dummy.h
+++ b/xen/include/xsm/dummy.h
@@ -453,7 +453,7 @@ static XSM_INLINE char *xsm_show_irq_sid
static XSM_INLINE int xsm_map_domain_pirq(XSM_DEFAULT_ARG struct domain *d)
{
- XSM_ASSERT_ACTION(XSM_TARGET);
+ XSM_ASSERT_ACTION(XSM_DM_PRIV);
return xsm_default_action(action, current->domain, d);
}
@@ -465,7 +465,7 @@ static XSM_INLINE int xsm_map_domain_irq
static XSM_INLINE int xsm_unmap_domain_pirq(XSM_DEFAULT_ARG struct domain *d)
{
- XSM_ASSERT_ACTION(XSM_TARGET);
+ XSM_ASSERT_ACTION(XSM_DM_PRIV);
return xsm_default_action(action, current->domain, d);
}
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