xen: use XSM instead of IS_PRIV where duplicated

The Xen hypervisor has two basic access control function calls:
IS_PRIV and the xsm_* functions. Most privileged operations currently
require that both checks succeed, and many times the checks are at
different locations in the code. This patch eliminates the explicit
and implicit IS_PRIV checks that are duplicated in XSM hooks.

When XSM_ENABLE is not defined or when the dummy XSM module is used,
this patch should not change any functionality. Because the locations
of privilege checks have sometimes moved below argument validation,
error returns of some functions may change from EPERM to EINVAL or
ESRCH if called with invalid arguments and from a domain without
permission to perform the operation.

Some checks are removed due to non-obvious duplicates in their
callers:

 * acpi_enter_sleep is checked in XENPF_enter_acpi_sleep
 * map_domain_pirq has IS_PRIV_FOR checked in its callers:
   * physdev_map_pirq checks when acquiring the RCU lock
   * ioapic_guest_write is checked in PHYSDEVOP_apic_write
 * PHYSDEVOP_{manage_pci_add,manage_pci_add_ext,pci_device_add} are
   checked by xsm_resource_plug_pci in pci_add_device
 * PHYSDEVOP_manage_pci_remove is checked by xsm_resource_unplug_pci
   in pci_remove_device
 * PHYSDEVOP_{restore_msi,restore_msi_ext} are checked by
   xsm_resource_setup_pci in pci_restore_msi_state
 * do_console_io has changed to IS_PRIV from an explicit domid==0

Signed-off-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>
Acked-by: Jan Beulich <jbeulich@suse.com>
Committed-by: Keir Fraser <keir@xen.org>

5 files changed, 6 insertions, 61 deletions

diff --git a/xen/arch/x86/acpi/power.c b/xen/arch/x86/acpi/power.c
index e60173f952..c693bd9dd4 100644
--- a/xen/arch/x86/acpi/power.c
+++ b/xen/arch/x86/acpi/power.c
@@ -239,7 +239,7 @@ static long enter_state_helper(void *data)
  */
 int acpi_enter_sleep(struct xenpf_enter_acpi_sleep *sleep)
 {
-    if ( !IS_PRIV(current->domain) || !acpi_sinfo.pm1a_cnt_blk.address )
+    if ( !acpi_sinfo.pm1a_cnt_blk.address )
         return -EPERM;
 
     /* Sanity check */
diff --git a/xen/arch/x86/cpu/mcheck/mce.c b/xen/arch/x86/cpu/mcheck/mce.c
index 8b542405ca..658774ad40 100644
--- a/xen/arch/x86/cpu/mcheck/mce.c
+++ b/xen/arch/x86/cpu/mcheck/mce.c
@@ -1293,9 +1293,6 @@ long do_mca(XEN_GUEST_HANDLE_PARAM(xen_mc_t) u_xen_mc)
     struct xen_mc_msrinject *mc_msrinject;
     struct xen_mc_mceinject *mc_mceinject;
 
-    if (!IS_PRIV(v->domain) )
-        return x86_mcerr(NULL, -EPERM);
-
     ret = xsm_do_mca();
     if ( ret )
         return x86_mcerr(NULL, ret);
diff --git a/xen/arch/x86/irq.c b/xen/arch/x86/irq.c
index 05cede5b53..238600af7e 100644
--- a/xen/arch/x86/irq.c
+++ b/xen/arch/x86/irq.c
@@ -1853,8 +1853,7 @@ int map_domain_pirq(
     ASSERT(spin_is_locked(&d->event_lock));
 
     if ( !IS_PRIV(current->domain) &&
-         !(IS_PRIV_FOR(current->domain, d) &&
-           irq_access_permitted(current->domain, pirq)))
+         !irq_access_permitted(current->domain, pirq))
         return -EPERM;
 
     if ( pirq < 0 || pirq >= d->nr_pirqs || irq < 0 || irq >= nr_irqs )
diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
index 81489ec2d5..af2eafa6f5 100644
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -4493,9 +4493,6 @@ long arch_memory_op(int op, XEN_GUEST_HANDLE_PARAM(void) arg)
         XEN_GUEST_HANDLE_PARAM(e820entry_t) buffer_param;
         unsigned int i;
 
-        if ( !IS_PRIV(current->domain) )
-            return -EINVAL;
-
         rc = xsm_machine_memory_map();
         if ( rc )
             return rc;
diff --git a/xen/arch/x86/physdev.c b/xen/arch/x86/physdev.c
index 7800473894..32a861a140 100644
--- a/xen/arch/x86/physdev.c
+++ b/xen/arch/x86/physdev.c
@@ -109,12 +109,6 @@ int physdev_map_pirq(domid_t domid, int type, int *index, int *pirq_p,
     if ( ret )
         return ret;
 
-    if ( !IS_PRIV_FOR(current->domain, d) )
-    {
-        ret = -EPERM;
-        goto free_domain;
-    }
-
     /* Verify or get irq. */
     switch ( type )
     {
@@ -238,10 +232,6 @@ int physdev_unmap_pirq(domid_t domid, int pirq)
             goto free_domain;
     }
 
-    ret = -EPERM;
-    if ( !IS_PRIV_FOR(current->domain, d) )
-        goto free_domain;
-
     ret = xsm_unmap_domain_pirq(d, domain_pirq_to_irq(d, pirq));
     if ( ret )
         goto free_domain;
@@ -433,9 +423,6 @@ ret_t do_physdev_op(int cmd, XEN_GUEST_HANDLE_PARAM(void) arg)
         ret = -EFAULT;
         if ( copy_from_guest(&apic, arg, 1) != 0 )
             break;
-        ret = -EPERM;
-        if ( !IS_PRIV(v->domain) )
-            break;
         ret = xsm_apic(v->domain, cmd);
         if ( ret )
             break;
@@ -450,9 +437,6 @@ ret_t do_physdev_op(int cmd, XEN_GUEST_HANDLE_PARAM(void) arg)
         ret = -EFAULT;
         if ( copy_from_guest(&apic, arg, 1) != 0 )
             break;
-        ret = -EPERM;
-        if ( !IS_PRIV(v->domain) )
-            break;
         ret = xsm_apic(v->domain, cmd);
         if ( ret )
             break;
@@ -467,8 +451,10 @@ ret_t do_physdev_op(int cmd, XEN_GUEST_HANDLE_PARAM(void) arg)
         if ( copy_from_guest(&irq_op, arg, 1) != 0 )
             break;
 
-        ret = -EPERM;
-        if ( !IS_PRIV(v->domain) )
+        /* Use the APIC check since this dummy hypercall should still only
+         * be called by the domain with access to program the ioapic */
+        ret = xsm_apic(v->domain, cmd);
+        if ( ret )
             break;
 
         /* Vector is only used by hypervisor, and dom0 shouldn't
@@ -517,9 +503,6 @@ ret_t do_physdev_op(int cmd, XEN_GUEST_HANDLE_PARAM(void) arg)
 
     case PHYSDEVOP_manage_pci_add: {
         struct physdev_manage_pci manage_pci;
-        ret = -EPERM;
-        if ( !IS_PRIV(v->domain) )
-            break;
         ret = -EFAULT;
         if ( copy_from_guest(&manage_pci, arg, 1) != 0 )
             break;
@@ -530,9 +513,6 @@ ret_t do_physdev_op(int cmd, XEN_GUEST_HANDLE_PARAM(void) arg)
 
     case PHYSDEVOP_manage_pci_remove: {
         struct physdev_manage_pci manage_pci;
-        ret = -EPERM;
-        if ( !IS_PRIV(v->domain) )
-            break;
         ret = -EFAULT;
         if ( copy_from_guest(&manage_pci, arg, 1) != 0 )
             break;
@@ -545,10 +525,6 @@ ret_t do_physdev_op(int cmd, XEN_GUEST_HANDLE_PARAM(void) arg)
         struct physdev_manage_pci_ext manage_pci_ext;
         struct pci_dev_info pdev_info;
 
-        ret = -EPERM;
-        if ( !IS_PRIV(current->domain) )
-            break;
-
         ret = -EFAULT;
         if ( copy_from_guest(&manage_pci_ext, arg, 1) != 0 )
             break;
@@ -571,10 +547,6 @@ ret_t do_physdev_op(int cmd, XEN_GUEST_HANDLE_PARAM(void) arg)
         struct physdev_pci_device_add add;
         struct pci_dev_info pdev_info;
 
-        ret = -EPERM;
-        if ( !IS_PRIV(current->domain) )
-            break;
-
         ret = -EFAULT;
         if ( copy_from_guest(&add, arg, 1) != 0 )
             break;
@@ -595,10 +567,6 @@ ret_t do_physdev_op(int cmd, XEN_GUEST_HANDLE_PARAM(void) arg)
     case PHYSDEVOP_pci_device_remove: {
         struct physdev_pci_device dev;
 
-        ret = -EPERM;
-        if ( !IS_PRIV(v->domain) )
-            break;
-
         ret = -EFAULT;
         if ( copy_from_guest(&dev, arg, 1) != 0 )
             break;
@@ -610,10 +578,6 @@ ret_t do_physdev_op(int cmd, XEN_GUEST_HANDLE_PARAM(void) arg)
     case PHYSDEVOP_pci_mmcfg_reserved: {
         struct physdev_pci_mmcfg_reserved info;
 
-        ret = -EPERM;
-        if ( !IS_PRIV(current->domain) )
-            break;
-
         ret = xsm_resource_setup_misc();
         if ( ret )
             break;
@@ -631,10 +595,6 @@ ret_t do_physdev_op(int cmd, XEN_GUEST_HANDLE_PARAM(void) arg)
         struct physdev_restore_msi restore_msi;
         struct pci_dev *pdev;
 
-        ret = -EPERM;
-        if ( !IS_PRIV(v->domain) )
-            break;
-
         ret = -EFAULT;
         if ( copy_from_guest(&restore_msi, arg, 1) != 0 )
             break;
@@ -650,10 +610,6 @@ ret_t do_physdev_op(int cmd, XEN_GUEST_HANDLE_PARAM(void) arg)
         struct physdev_pci_device dev;
         struct pci_dev *pdev;
 
-        ret = -EPERM;
-        if ( !IS_PRIV(v->domain) )
-            break;
-
         ret = -EFAULT;
         if ( copy_from_guest(&dev, arg, 1) != 0 )
             break;
@@ -668,10 +624,6 @@ ret_t do_physdev_op(int cmd, XEN_GUEST_HANDLE_PARAM(void) arg)
     case PHYSDEVOP_setup_gsi: {
         struct physdev_setup_gsi setup_gsi;
 
-        ret = -EPERM;
-        if ( !IS_PRIV(v->domain) )
-            break;
-
         ret = -EFAULT;
         if ( copy_from_guest(&setup_gsi, arg, 1) != 0 )
             break;