Implement MLS level lookup.

libqpol/include/qpol/mls_query.h

@@ -38,6 +38,7 @@ extern "C"
 	typedef struct qpol_cat qpol_cat_t;
 	typedef struct qpol_mls_range qpol_mls_range_t;
 	typedef struct qpol_mls_level qpol_mls_level_t;
+	typedef struct qpol_semantic_level qpol_semantic_level_t;
 
 #include <qpol/iterator.h>
 #include <qpol/policy.h>
@@ -253,6 +254,11 @@ extern "C"
 	extern int qpol_mls_level_get_cat_iter(const qpol_policy_t * policy, const qpol_mls_level_t * level,
 					       qpol_iterator_t ** cats);
 
+/* semantic levels */
+	extern int qpol_policy_get_semantic_level_by_name(const qpol_policy_t * policy, const char *name, const qpol_semantic_level_t ** datum);
+	extern int qpol_semantic_level_add_cats_by_name(const qpol_policy_t * policy, const qpol_semantic_level_t * level, const char *low, const char *high);
+	extern int qpol_mls_level_from_semantic_level(const qpol_policy_t * policy, const qpol_semantic_level_t * src, qpol_mls_level_t **dest);
+
 #ifdef	__cplusplus
 }
 #endif

libqpol/mls_query.c

@@ -6,7 +6,7 @@
  *  @author Jeremy A. Mowery jmowery@tresys.com
  *  @author Jason Tang jtang@tresys.com
  *
- *  Copyright (C) 2006-2007 Tresys Technology, LLC
+ *  Copyright (C) 2006-2007. 2015 Tresys Technology, LLC
  *
  *  This library is free software; you can redistribute it and/or
  *  modify it under the terms of the GNU Lesser General Public
@@ -637,3 +637,139 @@ int qpol_mls_level_get_cat_iter(const qpol_policy_t * policy, const qpol_mls_lev
 
 	return STATUS_SUCCESS;
 }
+
+int qpol_mls_level_from_semantic_level(const qpol_policy_t * policy, const qpol_semantic_level_t * src, qpol_mls_level_t **dest)
+{
+	policydb_t *db = NULL;
+	mls_semantic_level_t *internal_semantic = NULL;
+	mls_level_t *internal_level = NULL;
+
+	if (policy == NULL || src == NULL || dest == NULL) {
+		ERR(policy, "%s", strerror(EINVAL));
+		errno = EINVAL;
+		*dest = NULL;
+		return STATUS_ERR;
+	}
+
+	internal_semantic = (mls_semantic_level_t*) src;
+	db = &policy->p->p;
+
+	internal_level = malloc(sizeof(mls_level_t));
+	if (!internal_level) {
+		return STATUS_ERR;
+	}
+	mls_level_init(internal_level);
+
+	if(mls_semantic_level_expand(internal_semantic, internal_level, db, policy->sh) < 0) {
+		mls_level_destroy(internal_level);
+		free(internal_level);
+		errno = EINVAL;
+		*dest = NULL;
+		return STATUS_ERR;
+	}
+
+	*dest = (qpol_mls_level_t*) internal_level;
+
+	return STATUS_SUCCESS;
+}
+
+/* semantic level */
+int qpol_policy_get_semantic_level_by_name(const qpol_policy_t * policy, const char *name, const qpol_semantic_level_t ** datum)
+{
+	policydb_t *db = NULL;
+	hashtab_datum_t internal_datum = NULL;
+	mls_semantic_level_t *internal_semantic = NULL;
+
+	if (policy == NULL || name == NULL || datum == NULL) {
+		if (datum != NULL)
+			*datum = NULL;
+		ERR(policy, "%s", strerror(EINVAL));
+		errno = EINVAL;
+		return STATUS_ERR;
+	}
+
+	internal_semantic = malloc(sizeof(mls_semantic_level_t));
+	if (!internal_semantic) {
+		return STATUS_ERR;
+	}
+	mls_semantic_level_init(internal_semantic);
+
+	db = &policy->p->p;
+	internal_datum = hashtab_search(db->p_levels.table, (hashtab_key_t)name);
+	if (internal_datum == NULL) {
+		mls_semantic_level_destroy(internal_semantic);
+		free(internal_semantic);
+		*datum = NULL;
+		ERR(policy, "could not find datum for level %s", name);
+		errno = ENOENT;
+		return STATUS_ERR;
+	}
+
+	internal_semantic->sens = ((level_datum_t*)internal_datum)->level->sens;
+
+	*datum = (qpol_semantic_level_t *) internal_semantic;
+
+	return STATUS_SUCCESS;
+}
+
+int qpol_semantic_level_add_cats_by_name(const qpol_policy_t * policy, const qpol_semantic_level_t * level, const char *low, const char *high)
+{
+	hashtab_datum_t internal_datum;
+	policydb_t *db = NULL;
+	mls_semantic_level_t *internal_level = NULL;
+	mls_semantic_cat_t *internal_cat = NULL;
+
+	if (policy == NULL || level == NULL || low == NULL || high == NULL) {
+		ERR(policy, "%s", strerror(EINVAL));
+		errno = EINVAL;
+		return STATUS_ERR;
+	}
+
+	internal_cat = malloc(sizeof(mls_semantic_cat_t));
+	if (!internal_cat) {
+		return STATUS_ERR;
+	}
+	mls_semantic_cat_init(internal_cat);
+
+	db = &policy->p->p;
+	internal_level = (mls_semantic_level_t*) level;
+
+	internal_datum = hashtab_search(db->p_cats.table, (hashtab_key_t)low);
+	if (internal_datum == NULL) {
+		ERR(policy, "could not find datum for cat %s", low);
+		goto err;
+	}
+	internal_cat->low = ((cat_datum_t*)internal_datum)->s.value;
+
+	internal_datum = hashtab_search(db->p_cats.table, (hashtab_key_t)high);
+	if (internal_datum == NULL) {
+		ERR(policy, "could not find datum for cat %s", high);
+		goto err;
+	}
+	internal_cat->high = ((cat_datum_t*)internal_datum)->s.value;
+
+	if (internal_cat->low > internal_cat->high) {
+		ERR(policy, "invalid semantic category range: %s.%s", low, high);
+		goto err;
+	}
+
+	if (!(internal_level->cat)) {
+		internal_level->cat = internal_cat;
+	} else {
+		mls_semantic_cat_t *curr = internal_level->cat;
+
+		while(curr->next) {
+			curr = curr->next;
+		}
+
+		curr->next = internal_cat;
+	}
+
+	return STATUS_SUCCESS;
+
+  err:
+	mls_semantic_cat_destroy(internal_cat);
+	free(internal_cat);
+	errno = ENOENT;
+	return STATUS_ERR;
+}

setools/policyrep/mls.py

@@ -84,10 +84,47 @@ def level_factory(policy, symbol):
     Factory function for creating MLS level objects (e.g. levels used
     in contexts of labeling statements)
     """
-    if not isinstance(symbol, qpol.qpol_mls_level_t):
-        raise TypeError("MLS levels cannot be looked-up.")
+    if isinstance(symbol, qpol.qpol_mls_level_t):
+        return MLSLevel(policy, symbol)
 
-    return MLSLevel(policy, symbol)
+    # parse the level string and construct a semantic representation
+    sens_split = symbol.split(":")
+
+    sens = sens_split[0]
+    try:
+        semantic_level = qpol.qpol_semantic_level_t(policy, sens)
+    except ValueError:
+        raise InvalidLevel("{0} is not a valid sensitivity".format(sens))
+
+    try:
+        cats = sens_split[1]
+    except IndexError:
+        pass
+    else:
+        for group in cats.split(","):
+            catrange = group.split(".")
+
+            if len(catrange) == 2:
+                try:
+                    semantic_level.add_cats(policy, catrange[0], catrange[1])
+                except ValueError:
+                    raise InvalidLevel("{0} is not a valid category range".format(group))
+            elif len(catrange) == 1:
+                try:
+                    semantic_level.add_cats(policy, catrange[0], catrange[0])
+                except ValueError:
+                    raise InvalidLevel("{0} is not a valid category".format(group))
+            else:
+                # may not be possible to get here
+                raise InvalidLevel("{0} is not a valid category range".format(group))
+
+    # convert to level object
+    try:
+        policy_level = qpol.qpol_mls_level_t(policy, semantic_level)
+    except ValueError:
+        raise InvalidLevel("{0} is not a valid level".format(symbol))
+
+    return MLSLevel(policy, policy_level)
 
 
 def level_decl_factory(policy, symbol):

setools/policyrep/qpol.i

@@ -1561,16 +1561,57 @@ typedef struct qpol_mls_range {} qpol_mls_range_t;
     };
 %}
 
+/* qpol semantic mls level */
+typedef struct qpol_semantic_level {} qpol_semantic_level_t;
+%extend qpol_semantic_level {
+    %exception qpol_semantic_level {
+      $action
+      if (!result) {
+        PyErr_SetString(PyExc_ValueError, "Invalid sensitivity name.");
+        return NULL;
+      }
+    }
+
+    qpol_semantic_level(qpol_policy_t *p, const char *name) {
+        const qpol_semantic_level_t *l;
+        qpol_policy_get_semantic_level_by_name(p, name, &l);
+        return (qpol_semantic_level_t*)l;
+    };
+
+    ~qpol_semantic_level() {
+        /* mls_semantic_level_destroy(self); */
+        return;
+    };
+
+    %exception add_cats {
+      $action
+      if (result) {
+        PyErr_SetString(PyExc_ValueError, "Invalid category name or category range.");
+        return NULL;
+      }
+    }
+    int add_cats(qpol_policy_t *p, const char *low, const char *high) {
+        return qpol_semantic_level_add_cats_by_name(p, self, low, high);
+    }
+};
+
 /* qpol mls level */
 typedef struct qpol_mls_level {} qpol_mls_level_t;
 %extend qpol_mls_level {
-    qpol_mls_level() {
-        BEGIN_EXCEPTION
-        SWIG_exception(SWIG_RuntimeError, "Cannot directly create qpol_mls_level_t objects");
-        END_EXCEPTION
-    fail:
+    %exception qpol_mls_level {
+      $action
+      if (!result) {
+        PyErr_SetString(PyExc_ValueError, "Invalid level.");
         return NULL;
+      }
     }
+
+    qpol_mls_level(qpol_policy_t *p, qpol_semantic_level_t *l) {
+        qpol_mls_level_t *level;
+        qpol_mls_level_from_semantic_level(p, l, &level);
+        return level;
+    }
+
     ~qpol_mls_level() {
         /* no op */
         return;