[RFC PATCH v19 4/5] selftests/landlock: Add tests for execveat + AT_CHECK

["Mickaël Salaün" <mic@digikod.net>]

Extend layout1.execute with the new AT_CHECK flag.  The semantic with
AT_CHECK is the same as with a simple execve(2),
LANDLOCK_ACCESS_FS_EXECUTE is enforced the same way.

Cc: Günther Noack <gnoack@google.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Paul Moore <paul@paul-moore.com>
Signed-off-by: Mickaël Salaün <mic@digikod.net>
Link: https://lore.kernel.org/r/20240704190137.696169-5-mic@digikod.net
---
 tools/testing/selftests/landlock/fs_test.c | 26 ++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/tools/testing/selftests/landlock/fs_test.c b/tools/testing/selftests/landlock/fs_test.c
index 7d063c652be1..85ef36b09a37 100644
--- a/tools/testing/selftests/landlock/fs_test.c
+++ b/tools/testing/selftests/landlock/fs_test.c
@@ -37,6 +37,10 @@
 #include <linux/fs.h>
 #include <linux/mount.h>
 
+/* Defines AT_CHECK without type conflicts. */
+#define _ASM_GENERIC_FCNTL_H
+#include <linux/fcntl.h>
+
 #include "common.h"
 
 #ifndef renameat2
@@ -2009,6 +2013,21 @@ static void test_execute(struct __test_metadata *const _metadata, const int err,
 	};
 }
 
+static void test_check_exec(struct __test_metadata *const _metadata,
+			    const int err, const char *const path)
+{
+	int ret;
+	char *const argv[] = { (char *)path, NULL };
+
+	ret = execveat(AT_FDCWD, path, argv, NULL, AT_EMPTY_PATH | AT_CHECK);
+	if (err) {
+		EXPECT_EQ(-1, ret);
+		EXPECT_EQ(errno, err);
+	} else {
+		EXPECT_EQ(0, ret);
+	}
+}
+
 TEST_F_FORK(layout1, execute)
 {
 	const struct rule rules[] = {
@@ -2026,20 +2045,27 @@ TEST_F_FORK(layout1, execute)
 	copy_binary(_metadata, file1_s1d2);
 	copy_binary(_metadata, file1_s1d3);
 
+	/* Checks before file1_s1d1 being denied. */
+	test_execute(_metadata, 0, file1_s1d1);
+	test_check_exec(_metadata, 0, file1_s1d1);
+
 	enforce_ruleset(_metadata, ruleset_fd);
 	ASSERT_EQ(0, close(ruleset_fd));
 
 	ASSERT_EQ(0, test_open(dir_s1d1, O_RDONLY));
 	ASSERT_EQ(0, test_open(file1_s1d1, O_RDONLY));
 	test_execute(_metadata, EACCES, file1_s1d1);
+	test_check_exec(_metadata, EACCES, file1_s1d1);
 
 	ASSERT_EQ(0, test_open(dir_s1d2, O_RDONLY));
 	ASSERT_EQ(0, test_open(file1_s1d2, O_RDONLY));
 	test_execute(_metadata, 0, file1_s1d2);
+	test_check_exec(_metadata, 0, file1_s1d2);
 
 	ASSERT_EQ(0, test_open(dir_s1d3, O_RDONLY));
 	ASSERT_EQ(0, test_open(file1_s1d3, O_RDONLY));
 	test_execute(_metadata, 0, file1_s1d3);
+	test_check_exec(_metadata, 0, file1_s1d3);
 }
 
 TEST_F_FORK(layout1, link)
-- 
2.45.2