sepolgen: parse gen_tunable as bool

Currently sepolgen-ifgen parses a gen_tunable statement as interface
and reports in verbose mode:

    Missing interface definition for gen_tunable

Add grammar for gen_tunable statements in the refparser

Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Acked-by: Stephen Smalley <stephen.smalley.work@gmail.com>

python/sepolgen/src/sepolgen/refparser.py

@@ -126,6 +126,7 @@
     'GEN_REQ',
     'TEMPLATE',
     'GEN_CONTEXT',
+    'GEN_TUNABLE',
     #   m4
     'IFELSE',
     'IFDEF',
@@ -192,6 +193,7 @@
     'gen_require' : 'GEN_REQ',
     'template' : 'TEMPLATE',
     'gen_context' : 'GEN_CONTEXT',
+    'gen_tunable' : 'GEN_TUNABLE',
     # M4
     'ifelse' : 'IFELSE',
     'ifndef' : 'IFNDEF',
@@ -518,6 +520,7 @@ def p_policy_stmt(p):
                    | range_transition_def
                    | role_transition_def
                    | bool
+                   | gen_tunable
                    | define
                    | initial_sid
                    | genfscon
@@ -844,6 +847,17 @@ def p_bool(p):
         b.state = False
     p[0] = b
 
+def p_gen_tunable(p):
+    '''gen_tunable : GEN_TUNABLE OPAREN TICK IDENTIFIER SQUOTE COMMA TRUE CPAREN
+                   | GEN_TUNABLE OPAREN TICK IDENTIFIER SQUOTE COMMA FALSE CPAREN'''
+    b = refpolicy.Bool()
+    b.name = p[4]
+    if p[7] == "true":
+        b.state = True
+    else:
+        b.state = False
+    p[0] = b
+
 def p_conditional(p):
     ''' conditional : IF OPAREN cond_expr CPAREN OBRACE interface_stmts CBRACE
                     | IF OPAREN cond_expr CPAREN OBRACE interface_stmts CBRACE ELSE OBRACE interface_stmts CBRACE