x86: remove IS_PRIV_FOR references

The check in guest_physmap_mark_populate_on_demand is redundant, since
its only caller is populate_physmap whose only caller checks the
xsm_memory_adjust_reservation hook prior to calling.

Add a new XSM hook for the other two checks since they allow privileged
domains to arbitrarily map a guest's memory.

Signed-off-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>
Acked-by: George Dunlap <george.dunlap@eu.citrix.com> (release perspective)

xen/arch/x86/mm.c

@@ -815,7 +815,7 @@ get_page_from_l1e(
          * minor hack can go away.
          */
         if ( (real_pg_owner == NULL) || (pg_owner == l1e_owner) ||
-             !IS_PRIV_FOR(pg_owner, real_pg_owner) )
+             xsm_priv_mapping(XSM_TARGET, pg_owner, real_pg_owner) )
         {
             MEM_LOG("pg_owner %d l1e_owner %d, but real_pg_owner %d",
                     pg_owner->domain_id, l1e_owner->domain_id,

xen/arch/x86/mm/p2m-pod.c

@@ -1117,9 +1117,6 @@ guest_physmap_mark_populate_on_demand(struct domain *d, unsigned long gfn,
     mfn_t omfn;
     int rc = 0;
 
-    if ( !IS_PRIV_FOR(current->domain, d) )
-        return -EPERM;
-
     if ( !paging_mode_translate(d) )
         return -EINVAL;
 

xen/arch/x86/mm/shadow/multi.c

@@ -29,6 +29,7 @@
 #include <xen/perfc.h>
 #include <xen/domain_page.h>
 #include <xen/iocap.h>
+#include <xsm/xsm.h>
 #include <asm/page.h>
 #include <asm/current.h>
 #include <asm/shadow.h>
@@ -849,14 +850,16 @@ shadow_get_page_from_l1e(shadow_l1e_t sl1e, struct domain *d, p2m_type_t type)
          !shadow_mode_translate(d) &&
          mfn_valid(mfn = shadow_l1e_get_mfn(sl1e)) &&
          (owner = page_get_owner(mfn_to_page(mfn))) &&
-         (d != owner) &&
-         IS_PRIV_FOR(d, owner))
+         (d != owner) )
     {
-        res = get_page_from_l1e(sl1e, d, owner);
-        SHADOW_PRINTK("privileged domain %d installs map of mfn %05lx "
-                       "which is owned by domain %d: %s\n",
-                       d->domain_id, mfn_x(mfn), owner->domain_id,
-                       res >= 0 ? "success" : "failed");
+        res = xsm_priv_mapping(XSM_TARGET, d, owner);
+        if ( !res ) {
+            res = get_page_from_l1e(sl1e, d, owner);
+            SHADOW_PRINTK("privileged domain %d installs map of mfn %05lx "
+                           "which is owned by domain %d: %s\n",
+                           d->domain_id, mfn_x(mfn), owner->domain_id,
+                           res >= 0 ? "success" : "failed");
+        }
     }
 
     /* Okay, it might still be a grant mapping PTE.  Try it. */

xen/include/xsm/dummy.h

@@ -574,6 +574,12 @@ static XSM_INLINE int xsm_update_va_mapping(XSM_DEFAULT_ARG struct domain *d, st
     return xsm_default_action(action, d, f);
 }
 
+static XSM_INLINE int xsm_priv_mapping(XSM_DEFAULT_ARG struct domain *d, struct domain *t)
+{
+    XSM_ASSERT_ACTION(XSM_TARGET);
+    return xsm_default_action(action, d, t);
+}
+
 static XSM_INLINE int xsm_bind_pt_irq(XSM_DEFAULT_ARG struct domain *d, struct xen_domctl_bind_pt_irq *bind)
 {
     XSM_ASSERT_ACTION(XSM_HOOK);

xen/include/xsm/xsm.h

@@ -154,6 +154,7 @@ struct xsm_operations {
                        struct domain *f, uint32_t flags);
     int (*mmuext_op) (struct domain *d, struct domain *f);
     int (*update_va_mapping) (struct domain *d, struct domain *f, l1_pgentry_t pte);
+    int (*priv_mapping) (struct domain *d, struct domain *t);
     int (*bind_pt_irq) (struct domain *d, struct xen_domctl_bind_pt_irq *bind);
     int (*unbind_pt_irq) (struct domain *d, struct xen_domctl_bind_pt_irq *bind);
     int (*ioport_permission) (struct domain *d, uint32_t s, uint32_t e, uint8_t allow);
@@ -582,6 +583,11 @@ static inline int xsm_update_va_mapping(xsm_default_t def, struct domain *d, str
     return xsm_ops->update_va_mapping(d, f, pte);
 }
 
+static inline int xsm_priv_mapping(xsm_default_t def, struct domain *d, struct domain *t)
+{
+    return xsm_ops->priv_mapping(d, t);
+}
+
 static inline int xsm_bind_pt_irq(xsm_default_t def, struct domain *d,
                                                 struct xen_domctl_bind_pt_irq *bind)
 {

xen/xsm/dummy.c

@@ -124,6 +124,7 @@ void xsm_fixup_ops (struct xsm_operations *ops)
     set_to_dummy_if_null(ops, mmu_update);
     set_to_dummy_if_null(ops, mmuext_op);
     set_to_dummy_if_null(ops, update_va_mapping);
+    set_to_dummy_if_null(ops, priv_mapping);
     set_to_dummy_if_null(ops, bind_pt_irq);
     set_to_dummy_if_null(ops, unbind_pt_irq);
     set_to_dummy_if_null(ops, ioport_permission);

xen/xsm/flask/hooks.c

@@ -1345,6 +1345,11 @@ static int flask_update_va_mapping(struct domain *d, struct domain *f,
     return domain_has_perm(d, f, SECCLASS_MMU, map_perms);
 }
 
+static int flask_priv_mapping(struct domain *d, struct domain *t)
+{
+    return domain_has_perm(d, t, SECCLASS_MMU, MMU__TARGET_HACK);
+}
+
 static int flask_get_device_group(uint32_t machine_bdf)
 {
     u32 rsid;
@@ -1534,6 +1539,7 @@ static struct xsm_operations flask_ops = {
     .mmu_update = flask_mmu_update,
     .mmuext_op = flask_mmuext_op,
     .update_va_mapping = flask_update_va_mapping,
+    .priv_mapping = flask_priv_mapping,
     .get_device_group = flask_get_device_group,
     .test_assign_device = flask_test_assign_device,
     .assign_device = flask_assign_device,

xen/xsm/flask/policy/access_vectors

@@ -330,6 +330,9 @@ class mmu
 #  source = domain making the hypercall
 #  target = domain whose pages are being exchanged
     exchange
+# Allow a privileged domain to install a map of a page it does not own.  Used
+# for stub domain device models with the PV framebuffer.
+    target_hack
 }
 
 # control of the paging_domctl split by subop