tools/testing/selftests/landlock/scoped_signal_test.c

Source file repositories/reference/linux-study-clean/tools/testing/selftests/landlock/scoped_signal_test.c

File Facts

System
Linux kernel
Corpus path
tools/testing/selftests/landlock/scoped_signal_test.c
Extension
.c
Size
19046 bytes
Lines
745
Domain
Support Tooling And Documentation
Bucket
tools
Inferred role
Support Tooling And Documentation: implementation source
Status
source implementation candidate

Why This File Exists

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

Dependency Surface

Detected Declarations

Annotated Snippet

struct thread_setuid_args {
	int pipe_read, new_uid;
};

void *thread_setuid(void *ptr)
{
	const struct thread_setuid_args *arg = ptr;
	char buf;

	if (read(arg->pipe_read, &buf, 1) != 1)
		return (void *)THREAD_ERROR;

	/* libc's setuid() should update all thread's credentials. */
	if (getuid() != arg->new_uid)
		return (void *)THREAD_TEST_FAILED;

	return (void *)THREAD_SUCCESS;
}

TEST(signal_scoping_thread_setuid)
{
	struct thread_setuid_args arg;
	pthread_t no_sandbox_thread;
	enum thread_return ret = THREAD_INVALID;
	int pipe_parent[2];
	int prev_uid;

	disable_caps(_metadata);

	/* This test does not need to be run as root. */
	prev_uid = getuid();
	arg.new_uid = prev_uid + 1;
	EXPECT_LT(0, arg.new_uid);

	ASSERT_EQ(0, pipe2(pipe_parent, O_CLOEXEC));
	arg.pipe_read = pipe_parent[0];

	/* Capabilities must be set before creating a new thread. */
	set_cap(_metadata, CAP_SETUID);
	ASSERT_EQ(0, pthread_create(&no_sandbox_thread, NULL, thread_setuid,
				    &arg));

	/* Enforces restriction after creating the thread. */
	create_scoped_domain(_metadata, LANDLOCK_SCOPE_SIGNAL);

	EXPECT_NE(arg.new_uid, getuid());
	EXPECT_EQ(0, setuid(arg.new_uid));
	EXPECT_EQ(arg.new_uid, getuid());
	EXPECT_EQ(1, write(pipe_parent[1], ".", 1));

	EXPECT_EQ(0, pthread_join(no_sandbox_thread, (void **)&ret));
	EXPECT_EQ(THREAD_SUCCESS, ret);

	clear_cap(_metadata, CAP_SETUID);
	EXPECT_EQ(0, close(pipe_parent[0]));
	EXPECT_EQ(0, close(pipe_parent[1]));
}

const short backlog = 10;

static volatile sig_atomic_t signal_received;

static void handle_sigurg(int sig)
{
	if (sig == SIGURG)
		signal_received = 1;
	else
		signal_received = -1;
}

static int setup_signal_handler(int signal)
{
	struct sigaction sa = {
		.sa_handler = handle_sigurg,
	};

	if (sigemptyset(&sa.sa_mask))
		return -1;

	sa.sa_flags = SA_SIGINFO | SA_RESTART;
	return sigaction(SIGURG, &sa, NULL);
}

/* clang-format off */
FIXTURE(fown) {};
/* clang-format on */

enum fown_sandbox {
	SANDBOX_NONE,
	SANDBOX_BEFORE_FORK,

Annotation

Implementation Notes