libsepol/cil: Add CIL bounds checking and reporting.

Use the libsepol bounds checking to check for and report user and
role bounds violations.

For type bounds checking, use libsepol bounds checking to determine
if there is a violation for a given type. For each violation display
an error message that includes the CIL AST from the root node to the
node of the rule causing the violation.

Example error report:
Child type b_t3_c exceeds bounds of parent b_t3
  (allow b_t3_c b_tc (file (write)))
    <root>
    booleanif at line 148633 of cil.conf.bounds
    true at line 148634 of cil.conf.bounds
    allow at line 148636 of cil.conf.bounds
      (allow b_t3_c b_tc (file (read write)))

Signed-off-by: James Carter <jwcart2@tycho.nsa.gov>

libsepol/cil/src/cil_binary.c

@@ -3903,6 +3903,130 @@ exit:
 	return rc;
 }
 
+static struct cil_list *cil_classperms_from_sepol(policydb_t *pdb, uint16_t class, uint32_t data, struct cil_class *class_value_to_cil[], struct cil_perm **perm_value_to_cil[])
+{
+	struct cil_classperms *cp;
+	struct cil_list *cp_list;
+	class_datum_t *sepol_class = pdb->class_val_to_struct[class - 1];
+	unsigned i;
+
+	cil_classperms_init(&cp);
+
+	cp->class = class_value_to_cil[class];
+	if (!cp->class) goto exit;
+
+	cil_list_init(&cp->perms, CIL_PERM);
+	for (i = 0; i < sepol_class->permissions.nprim; i++) {
+		struct cil_perm *perm;
+		if ((data & (1 << i)) == 0) continue;
+		perm = perm_value_to_cil[class][i+1];
+		if (!perm) goto exit;
+		cil_list_append(cp->perms, CIL_PERM, perm);
+	}
+
+	cil_list_init(&cp_list, CIL_CLASSPERMS);
+	cil_list_append(cp_list, CIL_CLASSPERMS, cp);
+
+	return cp_list;
+
+exit:
+	cil_log(CIL_ERR,"Failed to create CIL class-permissions from sepol values\n");
+	return NULL;
+}
+
+static int cil_avrule_from_sepol(policydb_t *pdb, avtab_ptr_t sepol_rule, struct cil_avrule *cil_rule, void *type_value_to_cil[], struct cil_class *class_value_to_cil[], struct cil_perm **perm_value_to_cil[])
+{
+	int rc = SEPOL_ERR;
+	avtab_key_t *k = &sepol_rule->key;
+	avtab_datum_t *d = &sepol_rule->datum;
+	cil_rule->src = type_value_to_cil[k->source_type];
+	if (!cil_rule->src) goto exit;
+
+	cil_rule->tgt = type_value_to_cil[k->target_type];
+	if (!cil_rule->tgt) goto exit;
+
+	cil_rule->classperms = cil_classperms_from_sepol(pdb, k->target_class, d->data, class_value_to_cil, perm_value_to_cil);
+	if (!cil_rule->classperms) goto exit;
+
+	return SEPOL_OK;
+
+exit:
+	cil_log(CIL_ERR,"Failed to create CIL AV rule from sepol values\n");
+	return rc;
+}
+
+static int cil_check_type_bounds(const struct cil_db *db, policydb_t *pdb, void *type_value_to_cil, struct cil_class *class_value_to_cil[], struct cil_perm **perm_value_to_cil[])
+{
+	int rc = SEPOL_OK;
+	int i;
+
+	for (i = 0; i < db->num_types; i++) {
+		type_datum_t *child;
+		type_datum_t *parent;
+		avtab_ptr_t bad = NULL;
+		int numbad = 0;
+		struct cil_type *t = db->val_to_type[i];
+
+		if (!t->bounds) continue;
+
+		rc = __cil_get_sepol_type_datum(pdb, DATUM(t), &child);
+		if (rc != SEPOL_OK) goto exit;
+
+		rc = __cil_get_sepol_type_datum(pdb, DATUM(t->bounds), &parent);
+		if (rc != SEPOL_OK) goto exit;
+
+		rc = bounds_check_type(NULL, pdb, child->s.value, parent->s.value, &bad, &numbad);
+		if (rc != SEPOL_OK) goto exit;
+
+		if (bad) {
+			avtab_ptr_t cur;
+			struct cil_avrule target;
+
+			target.rule_kind = CIL_AVRULE_ALLOWED;
+			target.src_str = NULL;
+			target.tgt_str = NULL;
+
+			cil_log(CIL_ERR, "Child type %s exceeds bounds of parent %s\n",
+				t->datum.fqn, t->bounds->datum.fqn);
+			for (cur = bad; cur; cur = cur->next) {
+				struct cil_list_item *i2;
+				struct cil_list *matching;
+				struct cil_tree_node *n;
+
+				rc = cil_avrule_from_sepol(pdb, cur, &target, type_value_to_cil, class_value_to_cil, perm_value_to_cil);
+				if (rc != SEPOL_OK) {
+					cil_log(CIL_ERR, "Failed to convert sepol avrule to CIL\n");
+					goto exit;
+				}
+				__cil_print_rule("  ", "allow", &target);
+				cil_list_init(&matching, CIL_NODE);
+				rc = cil_find_matching_avrule_in_ast(db->ast->root, CIL_AVRULE, &target, matching, CIL_FALSE);
+				if (rc) {
+					cil_log(CIL_ERR, "Error occurred while checking type bounds\n");
+					cil_list_destroy(&matching, CIL_FALSE);
+					cil_list_destroy(&target.classperms, CIL_TRUE);
+					bounds_destroy_bad(bad);
+					goto exit;
+				}
+
+				cil_list_for_each(i2, matching) {
+					__cil_print_parents("    ", (struct cil_tree_node *)i2->data);
+				}
+				i2 = matching->tail;
+				n = i2->data;
+				__cil_print_rule("      ", "allow", n->data);
+				cil_log(CIL_ERR,"\n");
+				cil_list_destroy(&matching, CIL_FALSE);
+				cil_list_destroy(&target.classperms, CIL_TRUE);
+			}
+			bounds_destroy_bad(bad);
+		}
+	}
+
+exit:
+	return rc;
+}
+
 // assumes policydb is already allocated and initialized properly with things
 // like policy type set to kernel and version set appropriately
 int cil_binary_create_allocated_pdb(const struct cil_db *db, sepol_policydb_t *policydb)
@@ -4022,6 +4146,17 @@ int cil_binary_create_allocated_pdb(const struct cil_db *db, sepol_policydb_t *p
 		cil_log(CIL_INFO, "Checking Neverallows\n");
 		rc = cil_check_neverallows(db, pdb, neverallows);
 		if (rc != SEPOL_OK) goto exit;
+
+		cil_log(CIL_INFO, "Checking User Bounds\n");
+		bounds_check_users(NULL, pdb);
+
+		cil_log(CIL_INFO, "Checking Role Bounds\n");
+		bounds_check_roles(NULL, pdb);
+
+		cil_log(CIL_INFO, "Checking Type Bounds\n");
+		rc = cil_check_type_bounds(db, pdb, type_value_to_cil, class_value_to_cil, perm_value_to_cil);
+		if (rc != SEPOL_OK) goto exit;
+
 	}
 
 	rc = SEPOL_OK;