OS-5576 harden random pool for zones
Reviewed by: Patrick Mooney <patrick.mooney@joyent.com>

*** 18,27 ****
--- 18,29 ----
   *
   * CDDL HEADER END
   *
   * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
   * Use is subject to license terms.
+  *
+  * Copyright 2016 Joyent, Inc.
   */
  
  
  /*
   * Random number generator pseudo-driver
*** 287,296 ****
--- 289,301 ----
                  /* See comments in rnd_read() */
                  uiop->uio_loffset = 0;
                  if ((error = uiomove(buf, bytes, UIO_WRITE, uiop)) != 0)
                          return (error);
  
+                 if (crgetzone(credp) != global_zone)
+                         continue;
+ 
                  switch (devno) {
                  case DEVRANDOM:
                          if ((error = random_add_entropy(buf, bytes, 0)) != 0)
                                  return (error);
                          break;