libsepol/0012-libsepol-cil-Give-error-for-more-than-one-true-or-fa.patch

From 3b26f0566698926ba38cbf3fa702f3ff78862c5e Mon Sep 17 00:00:00 2001
From: James Carter <jwcart2@gmail.com>
Date: Tue, 20 Oct 2020 09:28:56 -0400
Subject: [PATCH] libsepol/cil: Give error for more than one true or false
 block

Both tunableif and booleanif use conditional blocks (either true or
false). No ordering is imposed, so a false block can be first (or even
the only) block. Checks are made to ensure that the first and second
(if it exists) blocks are either true or false, but no checks are made
to ensure that there is only one true and/or one false block. If there
are more than one true or false block, only the first will be used and
the other will be ignored.

Create a function, cil_verify_conditional_blocks(), that gives an error
along with a message if more than one true or false block is specified
and call that function when building tunableif and booleanif blocks in
the AST.

Signed-off-by: James Carter <jwcart2@gmail.com>
Acked-by: Ondrej Mosnacek <omosnace@redhat.com>
---
 libsepol/cil/src/cil_build_ast.c | 44 +++++---------------------------
 libsepol/cil/src/cil_verify.c    | 35 +++++++++++++++++++++++++
 libsepol/cil/src/cil_verify.h    |  1 +
 3 files changed, 42 insertions(+), 38 deletions(-)

diff --git a/libsepol/cil/src/cil_build_ast.c b/libsepol/cil/src/cil_build_ast.c
index 3aabb05ec534..a895583404a7 100644
--- a/libsepol/cil/src/cil_build_ast.c
+++ b/libsepol/cil/src/cil_build_ast.c
@@ -2821,7 +2821,6 @@ int cil_gen_boolif(struct cil_db *db, struct cil_tree_node *parse_current, struc
 	int syntax_len = sizeof(syntax)/sizeof(*syntax);
 	struct cil_booleanif *bif = NULL;
 	struct cil_tree_node *next = NULL;
-	struct cil_tree_node *cond = NULL;
 	int rc = SEPOL_ERR;
 
 	if (db == NULL || parse_current == NULL || ast_node == NULL) {
@@ -2841,27 +2840,12 @@ int cil_gen_boolif(struct cil_db *db, struct cil_tree_node *parse_current, struc
 		goto exit;
 	}
 
-	cond = parse_current->next->next;
-
-	/* Destroying expr tree after stack is created*/
-	if (cond->cl_head->data != CIL_KEY_CONDTRUE &&
-		cond->cl_head->data != CIL_KEY_CONDFALSE) {
-		rc = SEPOL_ERR;
-		cil_log(CIL_ERR, "Conditional neither true nor false\n");
+	rc = cil_verify_conditional_blocks(parse_current->next->next);
+	if (rc != SEPOL_OK) {
 		goto exit;
 	}
 
-	if (cond->next != NULL) {
-		cond = cond->next;
-		if (cond->cl_head->data != CIL_KEY_CONDTRUE &&
-			cond->cl_head->data != CIL_KEY_CONDFALSE) {
-			rc = SEPOL_ERR;
-			cil_log(CIL_ERR, "Conditional neither true nor false\n");
-			goto exit;
-		}
-	}
-
-
+	/* Destroying expr tree */
 	next = parse_current->next->next;
 	cil_tree_subtree_destroy(parse_current->next);
 	parse_current->next = next;
@@ -2905,7 +2889,6 @@ int cil_gen_tunif(struct cil_db *db, struct cil_tree_node *parse_current, struct
 	int syntax_len = sizeof(syntax)/sizeof(*syntax);
 	struct cil_tunableif *tif = NULL;
 	struct cil_tree_node *next = NULL;
-	struct cil_tree_node *cond = NULL;
 	int rc = SEPOL_ERR;
 
 	if (db == NULL || parse_current == NULL || ast_node == NULL) {
@@ -2924,27 +2907,12 @@ int cil_gen_tunif(struct cil_db *db, struct cil_tree_node *parse_current, struct
 		goto exit;
 	}
 
-	cond = parse_current->next->next;
-
-	if (cond->cl_head->data != CIL_KEY_CONDTRUE &&
-		cond->cl_head->data != CIL_KEY_CONDFALSE) {
-		rc = SEPOL_ERR;
-		cil_log(CIL_ERR, "Conditional neither true nor false\n");
+	rc = cil_verify_conditional_blocks(parse_current->next->next);
+	if (rc != SEPOL_OK) {
 		goto exit;
 	}
 
-	if (cond->next != NULL) {
-		cond = cond->next;
-
-		if (cond->cl_head->data != CIL_KEY_CONDTRUE &&
-			cond->cl_head->data != CIL_KEY_CONDFALSE) {
-			rc = SEPOL_ERR;
-			cil_log(CIL_ERR, "Conditional neither true nor false\n");
-			goto exit;
-		}
-	}
-
-	/* Destroying expr tree after stack is created*/
+	/* Destroying expr tree */
 	next = parse_current->next->next;
 	cil_tree_subtree_destroy(parse_current->next);
 	parse_current->next = next;
diff --git a/libsepol/cil/src/cil_verify.c b/libsepol/cil/src/cil_verify.c
index c73bbeee371b..6706e21921fe 100644
--- a/libsepol/cil/src/cil_verify.c
+++ b/libsepol/cil/src/cil_verify.c
@@ -324,6 +324,41 @@ exit:
 	return SEPOL_ERR;
 }
 
+int cil_verify_conditional_blocks(struct cil_tree_node *current)
+{
+	int found_true = CIL_FALSE;
+	int found_false = CIL_FALSE;
+
+	if (current->cl_head->data == CIL_KEY_CONDTRUE) {
+		found_true = CIL_TRUE;
+	} else if (current->cl_head->data == CIL_KEY_CONDFALSE) {
+		found_false = CIL_TRUE;
+	} else {
+		cil_tree_log(current, CIL_ERR, "Expected true or false block in conditional");
+		return SEPOL_ERR;
+	}
+
+	current = current->next;
+	if (current != NULL) {
+		if (current->cl_head->data == CIL_KEY_CONDTRUE) {
+			if (found_true) {
+				cil_tree_log(current, CIL_ERR, "More than one true block in conditional");
+				return SEPOL_ERR;
+			}
+		} else if (current->cl_head->data == CIL_KEY_CONDFALSE) {
+			if (found_false) {
+				cil_tree_log(current, CIL_ERR, "More than one false block in conditional");
+				return SEPOL_ERR;
+			}
+		} else {
+			cil_tree_log(current, CIL_ERR, "Expected true or false block in conditional");
+			return SEPOL_ERR;
+		}
+	}
+
+	return SEPOL_OK;
+}
+
 int cil_verify_no_self_reference(struct cil_symtab_datum *datum, struct cil_list *datum_list)
 {
 	struct cil_list_item *i;
diff --git a/libsepol/cil/src/cil_verify.h b/libsepol/cil/src/cil_verify.h
index bda1565fced5..905761b0a19c 100644
--- a/libsepol/cil/src/cil_verify.h
+++ b/libsepol/cil/src/cil_verify.h
@@ -61,6 +61,7 @@ int __cil_verify_syntax(struct cil_tree_node *parse_current, enum cil_syntax s[]
 int cil_verify_expr_syntax(struct cil_tree_node *current, enum cil_flavor op, enum cil_flavor expr_flavor);
 int cil_verify_constraint_leaf_expr_syntax(enum cil_flavor l_flavor, enum cil_flavor r_flavor, enum cil_flavor op, enum cil_flavor expr_flavor);
 int cil_verify_constraint_expr_syntax(struct cil_tree_node *current, enum cil_flavor op);
+int cil_verify_conditional_blocks(struct cil_tree_node *current);
 int cil_verify_no_self_reference(struct cil_symtab_datum *datum, struct cil_list *datum_list);
 int __cil_verify_ranges(struct cil_list *list);
 int __cil_verify_ordered_node_helper(struct cil_tree_node *node, uint32_t *finished, void *extra_args);
-- 
2.29.2