CVE-2019-3824 ldb: Add tests for ldb_wildcard_match

Add cmocka tests for ldb_wildcard_match.

Running test_wildcard_match under valgrind reproduces
 CVE-2019-3824 out of bounds read in wildcard compare (bug 13773)

 valgrind --suppressions=lib/ldb/tests/ldb_match_test.valgrind\
          bin/ldb_match_test

BUG: https://bugzilla.samba.org/show_bug.cgi?id=13773

Signed-off-by: Gary Lockyer <gary@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>

lib/ldb/tests/ldb_match_test.c

@@ -0,0 +1,191 @@
+/*
+ * Tests exercising the ldb match operations.
+ *
+ *
+ * Copyright (C) Catalyst.NET Ltd 2017
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+/*
+ * from cmocka.c:
+ * These headers or their equivalents should be included prior to
+ * including
+ * this header file.
+ *
+ * #include <stdarg.h>
+ * #include <stddef.h>
+ * #include <setjmp.h>
+ *
+ * This allows test applications to use custom definitions of C standard
+ * library functions and types.
+ */
+#include <stdarg.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <setjmp.h>
+#include <cmocka.h>
+
+#include "../common/ldb_match.c"
+
+#include "../include/ldb.h"
+
+struct ldbtest_ctx {
+	struct tevent_context *ev;
+	struct ldb_context *ldb;
+};
+
+static int ldb_test_canonicalise(
+	struct ldb_context *ldb,
+	void *mem_ctx,
+	const struct ldb_val *in,
+	struct ldb_val *out)
+{
+	out->length = in->length;
+	out->data = in->data;
+	return 0;
+}
+
+static int setup(void **state)
+{
+	struct ldbtest_ctx *test_ctx;
+	struct ldb_schema_syntax *syntax = NULL;
+	int ret;
+
+	test_ctx = talloc_zero(NULL, struct ldbtest_ctx);
+	assert_non_null(test_ctx);
+
+	test_ctx->ev = tevent_context_init(test_ctx);
+	assert_non_null(test_ctx->ev);
+
+	test_ctx->ldb = ldb_init(test_ctx, test_ctx->ev);
+	assert_non_null(test_ctx->ldb);
+
+	syntax = talloc_zero(test_ctx, struct ldb_schema_syntax);
+	assert_non_null(syntax);
+	syntax->canonicalise_fn = ldb_test_canonicalise;
+
+	ret = ldb_schema_attribute_add_with_syntax(
+	    test_ctx->ldb, "a", LDB_ATTR_FLAG_FIXED, syntax);
+	assert_int_equal(LDB_SUCCESS, ret);
+
+	*state = test_ctx;
+	return 0;
+}
+
+static int teardown(void **state)
+{
+	talloc_free(*state);
+	return 0;
+}
+
+
+/*
+ * The wild card pattern "attribute=*" is parsed as an LDB_OP_PRESENT operation
+ * rather than a LDB_OP_????
+ *
+ * This test serves to document that behaviour, and to confirm that
+ * ldb_wildcard_compare handles this case appropriately.
+ */
+static void test_wildcard_match_star(void **state)
+{
+	struct ldbtest_ctx *ctx = *state;
+	bool matched = false;
+	int ret;
+
+	uint8_t value[] = "The value.......end";
+	struct ldb_val val = {
+		.data   = value,
+		.length = (sizeof(value))
+	};
+	struct ldb_parse_tree *tree = ldb_parse_tree(ctx, "a=*");
+	assert_non_null(tree);
+
+	ret = ldb_wildcard_compare(ctx->ldb, tree, val, &matched);
+	assert_false(matched);
+	assert_int_equal(LDB_ERR_INAPPROPRIATE_MATCHING, ret);
+}
+
+/*
+ * Test basic wild card matching
+ *
+ */
+static void test_wildcard_match(void **state)
+{
+	struct ldbtest_ctx *ctx = *state;
+	bool matched = false;
+
+	uint8_t value[] = "The value.......end";
+	struct ldb_val val = {
+		.data   = value,
+		.length = (sizeof(value))
+	};
+	struct ldb_parse_tree *tree = ldb_parse_tree(ctx, "objectClass=*end");
+	assert_non_null(tree);
+
+	ldb_wildcard_compare(ctx->ldb, tree, val, &matched);
+	assert_true(matched);
+}
+
+
+/*
+ * ldb_handler_copy and ldb_val_dup over allocate by one and add a trailing '\0'
+ * to the data, to make them safe to use the C string functions on.
+ *
+ * However testing for the trailing '\0' is not the correct way to test for
+ * the end of a value, the length should be checked instead.
+ */
+static void test_wildcard_match_end_condition(void **state)
+{
+	struct ldbtest_ctx *ctx = *state;
+	bool matched = false;
+
+	uint8_t value[] = "hellomynameisbobx";
+	struct ldb_val val = {
+		.data   = talloc_memdup(NULL, value, sizeof(value)),
+		.length = (sizeof(value) - 2)
+	};
+	struct ldb_parse_tree *tree = ldb_parse_tree(ctx, "a=*hello*mynameis*bob");
+	assert_non_null(tree);
+
+	ldb_wildcard_compare(ctx->ldb, tree, val, &matched);
+	assert_true(matched);
+}
+
+/*
+ * Note: to run under valgrind use:
+ *       valgrind \
+ *           --suppressions=lib/ldb/tests/ldb_match_test.valgrind \
+ *           bin/ldb_match_test
+ */
+int main(int argc, const char **argv)
+{
+	const struct CMUnitTest tests[] = {
+		cmocka_unit_test_setup_teardown(
+			test_wildcard_match_star,
+			setup,
+			teardown),
+		cmocka_unit_test_setup_teardown(
+			test_wildcard_match,
+			setup,
+			teardown),
+		cmocka_unit_test_setup_teardown(
+			test_wildcard_match_end_condition,
+			setup,
+			teardown),
+	};
+
+	return cmocka_run_group_tests(tests, NULL, NULL);
+}

lib/ldb/tests/ldb_match_test.valgrind

@@ -0,0 +1,16 @@
+{
+   Memory allocated in set-up
+   Memcheck:Leak
+   match-leak-kinds: possible
+   fun:malloc
+   ...
+   fun:setup
+}
+{
+   Memory allocated by ldb_init
+   Memcheck:Leak
+   match-leak-kinds: possible
+   fun:malloc
+   ...
+   fun:ldb_init
+}

lib/ldb/wscript

@@ -511,6 +511,11 @@ def build(bld):
                          deps='cmocka ldb',
                          install=False)
 
+        bld.SAMBA_BINARY('ldb_match_test',
+                         source='tests/ldb_match_test.c',
+                         deps='cmocka ldb',
+                         install=False)
+
         if bld.CONFIG_SET('HAVE_LMDB'):
             bld.SAMBA_BINARY('ldb_mdb_mod_op_test',
                              source='tests/ldb_mod_op_test.c',
@@ -578,7 +583,8 @@ def test(ctx):
                  # we don't want to run ldb_lmdb_size_test (which proves we can
                  # fit > 4G of data into the DB), it would fill up the disk on
                  # many of our test instances
-                 'ldb_mdb_kv_ops_test']
+                 'ldb_mdb_kv_ops_test',
+                 'ldb_match_test']
 
     for test_exe in test_exes:
             cmd = os.path.join(Context.g_module.out, test_exe)