templates/20_linux_xen: Support Xen Security Modules (XSM/FLASK)

XSM is enabled by adding "flask=enforcing" as a Xen command line
argument, and providing the policy file as a grub module.

We make entries for both with and without XSM. If XSM is not compiled
into Xen, then there are no policy files, so no change to the boot
options.

Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>

util/grub.d/20_linux_xen.in

@@ -88,6 +88,11 @@ esac
 title_correction_code=
 
 linux_entry ()
+{
+  linux_entry_xsm "$@" false
+  linux_entry_xsm "$@" true
+}
+linux_entry_xsm ()
 {
   os="$1"
   version="$2"
@@ -95,6 +100,18 @@ linux_entry ()
   type="$4"
   args="$5"
   xen_args="$6"
+  xsm="$7"
+  # If user wants to enable XSM support, make sure there's
+  # corresponding policy file.
+  if ${xsm} ; then
+      xenpolicy="xenpolicy-$xen_version"
+      if test ! -e "${xen_dirname}/${xenpolicy}" ; then
+	  return
+      fi
+      xen_args="$xen_args flask=enforcing"
+      xen_version="$(gettext_printf "%s (XSM enabled)" "$xen_version")"
+      # xen_version is used for messages only; actual file is xen_basename
+  fi
   if [ -z "$boot_device_id" ]; then
       boot_device_id="$(grub_get_device_id "${GRUB_DEVICE}")"
   fi
@@ -146,6 +163,13 @@ EOF
     sed "s/^/$submenu_indentation/" << EOF
 	echo	'$(echo "$message" | grub_quote)'
 	${module_loader}	--nounzip   $(echo $initrd_path)
+EOF
+  fi
+  if test -n "${xenpolicy}" ; then
+    message="$(gettext_printf "Loading XSM policy ...")"
+    sed "s/^/$submenu_indentation/" << EOF
+	echo	'$(echo "$message" | grub_quote)'
+	${module_loader}     ${rel_dirname}/${xenpolicy}
 EOF
   fi
   sed "s/^/$submenu_indentation/" << EOF