[PATCH] libsepol: Change which attributes CIL keeps in the binary policy

[James Carter <jwcart2@xxxxxxxxxxxxx>]

The removal of attributes that are only used in neverallow rules is
hindering AOSP adoption of the CIL compiler. This is because AOSP
extracts neverallow rules from its policy.conf for use in the Android
compatibility test suite. These neverallow rules are applied against
the binary policy being tested to check for a violation. Any neverallow
rules with an attribute that has been removed cannot be checked.

Now attributes are kept unless they are not used in any allow rule and
they are auto-generated or named "cil_gen_require" or do not have any
types associated with them.

Signed-off-by: James Carter <jwcart2@xxxxxxxxxxxxx>
---
 libsepol/cil/src/cil_post.c  | 27 +++++++++++++++++++++++++++
 libsepol/src/module_to_cil.c |  8 +++++---
 2 files changed, 32 insertions(+), 3 deletions(-)

diff --git a/libsepol/cil/src/cil_post.c b/libsepol/cil/src/cil_post.c
index a694b33..f8447c9 100644
--- a/libsepol/cil/src/cil_post.c
+++ b/libsepol/cil/src/cil_post.c
@@ -47,6 +47,9 @@
 #include "cil_verify.h"
 #include "cil_symtab.h"
 
+#define GEN_REQUIRE_ATTR "cil_gen_require" /* Also in libsepol/src/module_to_cil.c */
+#define TYPEATTR_INFIX "_typeattr_"        /* Also in libsepol/src/module_to_cil.c */
+
 static int __cil_expr_to_bitmap(struct cil_list *expr, ebitmap_t *out, int max, struct cil_db *db);
 static int __cil_expr_list_to_bitmap(struct cil_list *expr_list, ebitmap_t *out, int max, struct cil_db *db);
 
@@ -1186,6 +1189,27 @@ exit:
 	return SEPOL_ERR;
 }
 
+static int cil_typeattribute_used(struct cil_typeattribute *cil_attr)
+{
+	if (cil_attr->used) {
+		return CIL_TRUE;
+	}
+
+	if (strcmp(DATUM(cil_attr)->name, GEN_REQUIRE_ATTR) == 0) {
+		return CIL_FALSE;
+	}
+
+	if (strstr(DATUM(cil_attr)->name,TYPEATTR_INFIX) != NULL) {
+		return CIL_FALSE;
+	}
+
+	if (ebitmap_cardinality(cil_attr->types) == 0) {
+		return CIL_FALSE;
+	}
+
+	return CIL_TRUE;
+}
+
 static int __cil_post_db_attr_helper(struct cil_tree_node *node, uint32_t *finished, void *extra_args)
 {
 	int rc = SEPOL_ERR;
@@ -1208,6 +1232,9 @@ static int __cil_post_db_attr_helper(struct cil_tree_node *node, uint32_t *finis
 		if (attr->types == NULL) {
 			rc = __evaluate_type_expression(attr, db);
 			if (rc != SEPOL_OK) goto exit;
+			if (cil_typeattribute_used(attr)) {
+				attr->used = CIL_TRUE;
+			}
 		}
 		break;
 	}
diff --git a/libsepol/src/module_to_cil.c b/libsepol/src/module_to_cil.c
index b9a4af7..bcbb4de 100644
--- a/libsepol/src/module_to_cil.c
+++ b/libsepol/src/module_to_cil.c
@@ -58,7 +58,9 @@ FILE *out_file;
 #define STACK_SIZE 16
 #define DEFAULT_LEVEL "systemlow"
 #define DEFAULT_OBJECT "object_r"
-#define GEN_REQUIRE_ATTR "cil_gen_require"
+#define GEN_REQUIRE_ATTR "cil_gen_require" /* Also in libsepol/cil/src/cil_post.c */
+#define TYPEATTR_INFIX "_typeattr_"        /* Also in libsepol/cil/src/cil_post.c */
+#define ROLEATTR_INFIX "_roleattr_"
 
 __attribute__ ((format(printf, 1, 2)))
 static void log_err(const char *fmt, ...)
@@ -626,9 +628,9 @@ static int set_to_cil_attr(struct policydb *pdb, int is_type, char ***names, uin
 	num_attrs++;
 
 	if (is_type) {
-		attr_infix = "_typeattr_";
+		attr_infix = TYPEATTR_INFIX;
 	} else {
-		attr_infix = "_roleattr_";
+		attr_infix = ROLEATTR_INFIX;
 	}
 
 	len = strlen(pdb->name) + strlen(attr_infix) + num_digits(num_attrs) + 1;
-- 
2.5.5

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