o The move to using VADMIN under vaccess() resulted in some system

calls returning EACCES instead of EPERM.  This patch modifies vaccess()
  to return EPERM instead of EACCES if VADMIN is among the requested
  rights.  This affects functions normally limited to the owners of
  a file, such as chmod(), as EPERM is the error indicating that
  privilege would allow the operation, rather than a chance in mandatory
  or discretionary rights.

Reported by:	bde

sys/kern/vfs_export.c

@@ -3128,5 +3128,5 @@ privcheck:
 	}
 #endif
 
-	return (EACCES);
+	return ((acc_mode & VADMIN) ? EPERM : EACCES);
 }

sys/kern/vfs_subr.c

@@ -3128,5 +3128,5 @@ privcheck:
 	}
 #endif
 
-	return (EACCES);
+	return ((acc_mode & VADMIN) ? EPERM : EACCES);
 }