Unverified Commit 0055f53a authored by Mickaël Salaün's avatar Mickaël Salaün
Browse files

selftests/landlock: Add layout1.refer_mount_root 

Add tests to check error codes when linking or renaming a mount root
directory.  This previously triggered a kernel warning, but it is fixed
with the previous commit.

Cc: Günther Noack <gnoack@google.com>
Cc: Paul Moore <paul@paul-moore.com>
Link: https://lore.kernel.org/r/20240516181935.1645983-3-mic@digikod.net


Signed-off-by: default avatarMickaël Salaün <mic@digikod.net>
parent 88da52cc

tools/testing/selftests/landlock/fs_test.c

+45 −0
Original line number Diff line number Diff line
@@ -35,6 +35,7 @@ 
 * See https://sourceware.org/glibc/wiki/Synchronizing_Headers.

 */

#include <linux/fs.h>

#include <linux/mount.h>



#include "common.h"
@@ -47,6 +48,13 @@ int renameat2(int olddirfd, const char *oldpath, int newdirfd, 
}

#endif



#ifndef open_tree

int open_tree(int dfd, const char *filename, unsigned int flags)

{

	return syscall(__NR_open_tree, dfd, filename, flags);

}

#endif



#ifndef RENAME_EXCHANGE

#define RENAME_EXCHANGE (1 << 1)

#endif
@@ -2400,6 +2408,43 @@ TEST_F_FORK(layout1, refer_denied_by_default4) 
				layer_dir_s1d1_refer);

}



/*

 * Tests walking through a denied root mount.

 */

TEST_F_FORK(layout1, refer_mount_root_deny)

{

	const struct landlock_ruleset_attr ruleset_attr = {

		.handled_access_fs = LANDLOCK_ACCESS_FS_MAKE_DIR,

	};

	int root_fd, ruleset_fd;



	/* Creates a mount object from a non-mount point. */

	set_cap(_metadata, CAP_SYS_ADMIN);

	root_fd =

		open_tree(AT_FDCWD, dir_s1d1,

			  AT_EMPTY_PATH | OPEN_TREE_CLONE | OPEN_TREE_CLOEXEC);

	clear_cap(_metadata, CAP_SYS_ADMIN);

	ASSERT_LE(0, root_fd);



	ruleset_fd =

		landlock_create_ruleset(&ruleset_attr, sizeof(ruleset_attr), 0);

	ASSERT_LE(0, ruleset_fd);



	ASSERT_EQ(0, prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0));

	ASSERT_EQ(0, landlock_restrict_self(ruleset_fd, 0));

	EXPECT_EQ(0, close(ruleset_fd));



	/* Link denied by Landlock: EACCES. */

	EXPECT_EQ(-1, linkat(root_fd, ".", root_fd, "does_not_exist", 0));

	EXPECT_EQ(EACCES, errno);



	/* renameat2() always returns EBUSY. */

	EXPECT_EQ(-1, renameat2(root_fd, ".", root_fd, "does_not_exist", 0));

	EXPECT_EQ(EBUSY, errno);



	EXPECT_EQ(0, close(root_fd));

}



TEST_F_FORK(layout1, reparent_link)

{

	const struct rule layer1[] = {