[PATCH -next v2 4/6] landlock/selftests: add selftests for chmod and chown

[Xiu Jianfeng]

The following APIs are tested with simple scenarios.
1. chmod/fchmod/fchmodat;
2. chmod/fchmod/lchown/fchownat;

The key point is that set these access rights on a directory but only for
its content, not the directory itself. this scenario is covered.

Signed-off-by: Xiu Jianfeng <xiujianfeng at huawei.com>
---
 tools/testing/selftests/landlock/fs_test.c | 261 +++++++++++++++++++++
 1 file changed, 261 insertions(+)

diff --git a/tools/testing/selftests/landlock/fs_test.c b/tools/testing/selftests/landlock/fs_test.c
index f513cd8d9d51..982cb824967c 100644
--- a/tools/testing/selftests/landlock/fs_test.c
+++ b/tools/testing/selftests/landlock/fs_test.c
@@ -3272,6 +3272,267 @@ TEST_F_FORK(layout1, truncate)
 	EXPECT_EQ(0, test_creat(file_in_dir_w));
 }
 
+/* Invokes chmod(2) and returns its errno or 0. */
+static int test_chmod(const char *const path, mode_t mode)
+{
+	if (chmod(path, mode) < 0)
+		return errno;
+	return 0;
+}
+
+/* Invokes fchmod(2) and returns its errno or 0. */
+static int test_fchmod(int fd, mode_t mode)
+{
+	if (fchmod(fd, mode) < 0)
+		return errno;
+	return 0;
+}
+
+/* Invokes fchmodat(2) and returns its errno or 0. */
+static int test_fchmodat(int dirfd, const char *path, mode_t mode, int flags)
+{
+	if (fchmodat(dirfd, path, mode, flags) < 0)
+		return errno;
+	return 0;
+}
+
+/* Invokes chown(2) and returns its errno or 0. */
+static int test_chown(const char *path, uid_t uid, gid_t gid)
+{
+	if (chown(path, uid, gid) < 0)
+		return errno;
+	return 0;
+}
+
+/* Invokes fchown(2) and returns its errno or 0. */
+static int test_fchown(int fd, uid_t uid, gid_t gid)
+{
+	if (fchown(fd, uid, gid) < 0)
+		return errno;
+	return 0;
+}
+
+/* Invokes lchown(2) and returns its errno or 0. */
+static int test_lchown(const char *path, uid_t uid, gid_t gid)
+{
+	if (lchown(path, uid, gid) < 0)
+		return errno;
+	return 0;
+}
+
+/* Invokes fchownat(2) and returns its errno or 0. */
+static int test_fchownat(int dirfd, const char *path,
+			 uid_t uid, gid_t gid, int flags)
+{
+	if (fchownat(dirfd, path, uid, gid, flags) < 0)
+		return errno;
+	return 0;
+}
+
+TEST_F_FORK(layout1, unhandled_chmod)
+{
+	int ruleset_fd, file1_fd;
+	const char *file1 = file1_s1d1;
+	const char *file2 = file2_s1d1;
+	const char *dir1 = dir_s1d1;
+	const struct rule rules[] = {
+		{
+			.path = file1,
+			.access = LANDLOCK_ACCESS_FS_WRITE_FILE,
+		},
+		{
+			.path = file2,
+			.access = LANDLOCK_ACCESS_FS_READ_FILE |
+				  LANDLOCK_ACCESS_FS_WRITE_FILE,
+		},
+		{
+			.path = dir1,
+			.access = ACCESS_RW,
+		},
+		{},
+	};
+
+	ruleset_fd = create_ruleset(_metadata, ACCESS_RW, rules);
+	ASSERT_LE(0, ruleset_fd);
+	file1_fd = open(file1, O_WRONLY | O_CLOEXEC);
+	ASSERT_LE(0, file1_fd);
+
+	enforce_ruleset(_metadata, ruleset_fd);
+	ASSERT_EQ(0, close(ruleset_fd));
+
+	EXPECT_EQ(0, test_chmod(file1, 0400));
+	EXPECT_EQ(0, test_fchmod(file1_fd, 0400));
+	EXPECT_EQ(0, test_fchmodat(AT_FDCWD, file1, 0400, 0));
+	EXPECT_EQ(0, test_chmod(file2, 0400));
+	EXPECT_EQ(0, test_chmod(dir1, 0700));
+	ASSERT_EQ(0, close(file1_fd));
+}
+
+TEST_F_FORK(layout1, chmod)
+{
+	int ruleset_fd, file1_fd;
+	const char *file1 = file1_s1d1;
+	const char *file2 = file2_s1d1;
+	const char *file3 = file1_s2d1;
+	const char *dir1 = dir_s1d1;
+	const char *dir2 = dir_s2d1;
+	const struct rule rules[] = {
+		{
+			.path = file1,
+			.access = LANDLOCK_ACCESS_FS_WRITE_FILE |
+				  LANDLOCK_ACCESS_FS_CHMOD,
+		},
+		{
+			.path = file2,
+			.access = LANDLOCK_ACCESS_FS_READ_FILE |
+				  LANDLOCK_ACCESS_FS_WRITE_FILE,
+		},
+		{
+			.path = dir1,
+			.access = ACCESS_RW,
+		},
+		{
+			.path = dir2,
+			.access = ACCESS_RW | LANDLOCK_ACCESS_FS_CHMOD,
+		},
+		{},
+	};
+
+	ruleset_fd = create_ruleset(_metadata, ACCESS_RW | LANDLOCK_ACCESS_FS_CHMOD, rules);
+	ASSERT_LE(0, ruleset_fd);
+	file1_fd = open(file1, O_WRONLY | O_CLOEXEC);
+	ASSERT_LE(0, file1_fd);
+
+	enforce_ruleset(_metadata, ruleset_fd);
+	ASSERT_EQ(0, close(ruleset_fd));
+
+	EXPECT_EQ(0, test_chmod(file1, 0400));
+	EXPECT_EQ(0, test_fchmod(file1_fd, 0400));
+	EXPECT_EQ(0, test_fchmodat(AT_FDCWD, file1, 0400, 0));
+	EXPECT_EQ(EACCES, test_chmod(file2, 0400));
+	EXPECT_EQ(EACCES, test_chmod(dir1, 0700));
+	/* set CHMOD right on dir will only affect its context not dir itself*/
+	EXPECT_EQ(0, test_chmod(file3, 0400));
+	EXPECT_EQ(0, test_fchmodat(AT_FDCWD, file3, 0400, 0));
+	EXPECT_EQ(EACCES, test_chmod(dir2, 0700));
+	EXPECT_EQ(EACCES, test_fchmodat(AT_FDCWD, dir2, 0700, 0));
+	ASSERT_EQ(0, close(file1_fd));
+}
+
+TEST_F_FORK(layout1, unhandled_chown)
+{
+	int ruleset_fd, file1_fd;
+	const char *file1 = file1_s1d1;
+	const char *file2 = file2_s1d1;
+	const char *dir1 = dir_s1d1;
+	const struct rule rules[] = {
+		{
+			.path = file1,
+			.access = LANDLOCK_ACCESS_FS_WRITE_FILE,
+		},
+		{
+			.path = file2,
+			.access = LANDLOCK_ACCESS_FS_READ_FILE |
+				  LANDLOCK_ACCESS_FS_WRITE_FILE,
+		},
+		{
+			.path = dir1,
+			.access = ACCESS_RW,
+		},
+		{},
+	};
+	struct stat st;
+	uid_t uid;
+	gid_t gid;
+
+	ruleset_fd = create_ruleset(_metadata, ACCESS_RW, rules);
+	ASSERT_LE(0, ruleset_fd);
+	file1_fd = open(file1, O_WRONLY | O_CLOEXEC);
+	ASSERT_LE(0, file1_fd);
+	/*
+	 * there is no CAP_CHOWN when the testcases framework setup,
+	 * and we cannot assume the testcases are run as root, to make
+	 * sure {f}chown syscall won't fail, get the original uid/gid and
+	 * use them in test_{f}chown.
+	 */
+	ASSERT_EQ(0, stat(dir1, &st));
+	uid = st.st_uid;
+	gid = st.st_gid;
+
+	enforce_ruleset(_metadata, ruleset_fd);
+	ASSERT_EQ(0, close(ruleset_fd));
+
+	EXPECT_EQ(0, test_chown(file1, uid, gid));
+	EXPECT_EQ(0, test_fchown(file1_fd, uid, gid));
+	EXPECT_EQ(0, test_lchown(file1, uid, gid));
+	EXPECT_EQ(0, test_fchownat(AT_FDCWD, file1, uid, gid, 0));
+	EXPECT_EQ(0, test_chown(file2, uid, gid));
+	EXPECT_EQ(0, test_chown(dir1, uid, gid));
+	ASSERT_EQ(0, close(file1_fd));
+}
+
+TEST_F_FORK(layout1, chown)
+{
+	int ruleset_fd, file1_fd;
+	const char *file1 = file1_s1d1;
+	const char *file2 = file2_s1d1;
+	const char *file3 = file1_s2d1;
+	const char *dir1 = dir_s1d1;
+	const char *dir2 = dir_s2d1;
+	const struct rule rules[] = {
+		{
+			.path = file1,
+			.access = LANDLOCK_ACCESS_FS_WRITE_FILE |
+				  LANDLOCK_ACCESS_FS_CHGRP,
+		},
+		{
+			.path = file2,
+			.access = LANDLOCK_ACCESS_FS_READ_FILE |
+				  LANDLOCK_ACCESS_FS_WRITE_FILE,
+		},
+		{
+			.path = dir1,
+			.access = ACCESS_RW,
+		},
+		{
+			.path = dir2,
+			.access = ACCESS_RW | LANDLOCK_ACCESS_FS_CHGRP,
+		},
+		{},
+	};
+	struct stat st;
+	uid_t uid;
+	gid_t gid;
+
+	ruleset_fd = create_ruleset(_metadata, ACCESS_RW | LANDLOCK_ACCESS_FS_CHGRP, rules);
+	ASSERT_LE(0, ruleset_fd);
+	file1_fd = open(file1, O_WRONLY | O_CLOEXEC);
+	ASSERT_LE(0, file1_fd);
+	/*
+	 * there is no CAP_CHOWN when the testcases framework setup,
+	 * and we cannot assume the testcases are run as root, to make
+	 * sure {f}chown syscall won't fail, get the original uid/gid and
+	 * use them in test_{f}chown.
+	 */
+	ASSERT_EQ(0, stat(dir1, &st));
+	uid = st.st_uid;
+	gid = st.st_gid;
+
+	enforce_ruleset(_metadata, ruleset_fd);
+	ASSERT_EQ(0, close(ruleset_fd));
+
+	EXPECT_EQ(0, test_chown(file1, uid, gid));
+	EXPECT_EQ(0, test_fchown(file1_fd, uid, gid));
+	EXPECT_EQ(0, test_lchown(file1, uid, gid));
+	EXPECT_EQ(0, test_fchownat(AT_FDCWD, file1, uid, gid, 0));
+	EXPECT_EQ(EACCES, test_chown(file2, uid, gid));
+	EXPECT_EQ(EACCES, test_chown(dir1, uid, gid));
+	/* set CHOWN right on dir will only affect its context not dir itself*/
+	EXPECT_EQ(0, test_chown(file3, uid, gid));
+	EXPECT_EQ(EACCES, test_chown(dir2, uid, gid));
+	ASSERT_EQ(0, close(file1_fd));
+}
+
 /* clang-format off */
 FIXTURE(layout1_bind) {};
 /* clang-format on */
-- 
2.17.1