[PATCH 3/3] libsepol/cil: Do not resolve names to declarations in abstract blocks

[James Carter <jwcart2@gmail.com>]

Since abstract blocks will not appear in the final policy, do not
resolve names to a declaration inside one.

When resolving blockabstract rules, they must be collected in a list
and processed at the end of the pass because if a parent block is
marked as abstract, then a blockabstract rule for a sub-block will
fail to resolve.

Found by oss-fuzz (#42981)

Signed-off-by: James Carter <jwcart2@gmail.com>
---
 libsepol/cil/src/cil_resolve_ast.c | 24 ++++++++++++++++++++----
 1 file changed, 20 insertions(+), 4 deletions(-)

diff --git a/libsepol/cil/src/cil_resolve_ast.c b/libsepol/cil/src/cil_resolve_ast.c
index 0288b7dc..73115c55 100644
--- a/libsepol/cil/src/cil_resolve_ast.c
+++ b/libsepol/cil/src/cil_resolve_ast.c
@@ -65,6 +65,7 @@ struct cil_args_resolve {
 	struct cil_list *sensitivityorder_lists;
 	struct cil_list *in_list_before;
 	struct cil_list *in_list_after;
+	struct cil_list *abstract_blocks;
 };
 
 static struct cil_name * __cil_insert_name(struct cil_db *db, hashtab_key_t key, struct cil_tree_node *ast_node)
@@ -2397,6 +2398,7 @@ int cil_resolve_blockabstract(struct cil_tree_node *current, void *extra_args)
 	struct cil_blockabstract *abstract = current->data;
 	struct cil_symtab_datum *block_datum = NULL;
 	struct cil_tree_node *block_node = NULL;
+	struct cil_args_resolve *args = extra_args;
 	int rc = SEPOL_ERR;
 
 	rc = cil_resolve_name(current, abstract->block_str, CIL_SYM_BLOCKS, extra_args, &block_datum);
@@ -2411,7 +2413,7 @@ int cil_resolve_blockabstract(struct cil_tree_node *current, void *extra_args)
 		goto exit;
 	}
 
-	cil_mark_subtree_abstract(block_node);
+	cil_list_append(args->abstract_blocks, CIL_NODE, block_node);
 
 	return SEPOL_OK;
 
@@ -4097,6 +4099,7 @@ int cil_resolve_ast(struct cil_db *db, struct cil_tree_node *current)
 	extra_args.sensitivityorder_lists = NULL;
 	extra_args.in_list_before = NULL;
 	extra_args.in_list_after = NULL;
+	extra_args.abstract_blocks = NULL;
 
 	cil_list_init(&extra_args.to_destroy, CIL_NODE);
 	cil_list_init(&extra_args.sidorder_lists, CIL_LIST_ITEM);
@@ -4106,6 +4109,7 @@ int cil_resolve_ast(struct cil_db *db, struct cil_tree_node *current)
 	cil_list_init(&extra_args.sensitivityorder_lists, CIL_LIST_ITEM);
 	cil_list_init(&extra_args.in_list_before, CIL_IN);
 	cil_list_init(&extra_args.in_list_after, CIL_IN);
+	cil_list_init(&extra_args.abstract_blocks, CIL_NODE);
 
 	for (pass = CIL_PASS_TIF; pass < CIL_PASS_NUM; pass++) {
 		extra_args.pass = pass;
@@ -4129,6 +4133,13 @@ int cil_resolve_ast(struct cil_db *db, struct cil_tree_node *current)
 			cil_list_destroy(&extra_args.in_list_after, CIL_FALSE);
 		}
 
+		if (pass == CIL_PASS_BLKABS) {
+			struct cil_list_item *item;
+			cil_list_for_each(item, extra_args.abstract_blocks) {
+				cil_mark_subtree_abstract(item->data);
+			}
+		}
+
 		if (pass == CIL_PASS_BLKIN_LINK) {
 			rc = cil_check_for_bad_inheritance(current);
 			if (rc != SEPOL_OK) {
@@ -4247,6 +4258,7 @@ exit:
 	cil_list_destroy(&extra_args.to_destroy, CIL_FALSE);
 	cil_list_destroy(&extra_args.in_list_before, CIL_FALSE);
 	cil_list_destroy(&extra_args.in_list_after, CIL_FALSE);
+	cil_list_destroy(&extra_args.abstract_blocks, CIL_FALSE);
 
 	return rc;
 }
@@ -4268,9 +4280,13 @@ static int __cil_resolve_name_with_parents(struct cil_tree_node *node, char *nam
 		case CIL_ROOT:
 			goto exit;
 			break;
-		case CIL_BLOCK:
-			symtab = &((struct cil_block*)node->data)->symtab[sym_index];
-			rc = cil_symtab_get_datum(symtab, name, datum);
+		case CIL_BLOCK: {
+			struct cil_block *block = node->data;
+			if (!block->is_abstract) {
+				symtab = &block->symtab[sym_index];
+				rc = cil_symtab_get_datum(symtab, name, datum);
+			}
+		}
 			break;
 		case CIL_BLOCKINHERIT: {
 			struct cil_blockinherit *inherit = node->data;
-- 
2.31.1