On Mon, Aug 19, 2024 at 10:08:53PM -0600, Tahera Fahimi wrote:

The patch introduces Landlock ABI version 6 and adds three types of tests
that examines different scenarios for abstract unix socket:
1) unix_socket: base tests of the abstract socket scoping mechanism for a
   landlocked process, same as the ptrace test.
2) optional_scoping: generates three processes with different domains and
   tests if a process with a non-scoped domain can connect to other
   processes.
3) outside_socket: since the socket's creator credentials are used
   for scoping sockets, this test examines the cases where the socket's
   credentials are different from the process using it.

Signed-off-by: Tahera Fahimi <redacted>
---
Changes in versions:
v10:
- Code improvements by changing fixture variables to local ones.
- Rename "unix_sock_special_cases" to "outside_socket"
v9:
- Move pathname_address_sockets to a different patch.
- Extend optional_scoping test scenarios.
- Removing hardcoded numbers and using "backlog" instead.
V8:
- Move tests to scoped_abstract_unix_test.c file.
- To avoid potential conflicts among Unix socket names in different tests,
  set_unix_address is added to common.h to set different sun_path for Unix sockets.
- protocol_variant and service_fixture structures are also moved to common.h
- Adding pathname_address_sockets to cover all types of address formats
  for unix sockets, and moving remove_path() to common.h to reuse in this test.
V7:
- Introducing landlock ABI version 6.
- Adding some edge test cases to optional_scoping test.
- Using `enum` for different domains in optional_scoping tests.
- Extend unix_sock_special_cases test cases for connected(SOCK_STREAM) sockets.
- Modifying inline comments.
V6:
- Introducing optional_scoping test which ensures a sandboxed process with a
  non-scoped domain can still connect to another abstract unix socket(either
  sandboxed or non-sandboxed).
- Introducing unix_sock_special_cases test which tests examines scenarios where
  the connecting sockets have different domain than the process using them.
V4:
- Introducing unix_socket to evaluate the basic scoping mechanism for abstract
  unix sockets.
---
 tools/testing/selftests/landlock/common.h     |  38 +
 tools/testing/selftests/landlock/net_test.c   |  31 +-
 .../landlock/scoped_abstract_unix_test.c      | 931 ++++++++++++++++++
 3 files changed, 970 insertions(+), 30 deletions(-)
 create mode 100644 tools/testing/selftests/landlock/scoped_abstract_unix_test.c

These variant fixture should be renamed to
FIXTURE_VARIANT(scoped_domains) to be usable for all scoped tests (e.g.
abstract unix socket and signal).  You can define them in a
scoped_common.h file which will be included by
scoped_abstract_unix_test.c and scoped_signal_test.c

+{
+	bool domain_both;
+	bool domain_parent;
+	bool domain_child;
+	bool connect_to_parent;

connect_to_parent should not be part of a variant.  In this case, we can
create two TEST_F(): a TEST_F(to_parent) like when connect_to_parent is
true, and a TEST_F(to_child) otherwise.

scoped_signal_test.c should have the same TEST_F names with slightly
different implementation but still testing the same semantic.

+};
+
+FIXTURE_SETUP(unix_socket)

The self->stream_address and self->dgram_address initializations were
good.  The issue was about socket's file descriptors, but if we have raw
data common to all tests, it makes sense to initialize them here.

+{
+}
+
+FIXTURE_TEARDOWN(unix_socket)
+{
+}
+
+/*
+ *        No domain
+ *
+ *   P1-.               P1 -> P2 : allow
+ *       \              P2 -> P1 : allow
+ *        'P2
+ */
+/* clang-format off */
+FIXTURE_VARIANT_ADD(unix_socket, allow_without_domain_connect_to_parent) {
+	/* clang-format on */
+	.domain_both = false,
+	.domain_parent = false,
+	.domain_child = false,
+	.connect_to_parent = true,
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(unix_socket, allow_without_domain_connect_to_child) {
+	/* clang-format on */
+	.domain_both = false,
+	.domain_parent = false,
+	.domain_child = false,
+	.connect_to_parent = false,

We can see that the picture describing the domains is the same for both
of these variants, which means something is wrong.  connect_to_parent
should not be part of the variant definitions.

+};
+
+/*
+ *        Child domain
+ *
+ *   P1--.              P1 -> P2 : allow
+ *        \             P2 -> P1 : deny
+ *        .'-----.
+ *        |  P2  |
+ *        '------'
+ */
+/* clang-format off */
+FIXTURE_VARIANT_ADD(unix_socket, deny_with_one_domain_connect_to_parent) {
+	/* clang-format on */
+	.domain_both = false,
+	.domain_parent = false,
+	.domain_child = true,
+	.connect_to_parent = true,
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(unix_socket, allow_with_one_domain_connect_to_child) {
+	/* clang-format on */
+	.domain_both = false,
+	.domain_parent = false,
+	.domain_child = true,
+	.connect_to_parent = false,
+};
+
+/*
+ *        Parent domain
+ * .------.
+ * |  P1  --.           P1 -> P2 : deny
+ * '------'  \          P2 -> P1 : allow
+ *            '
+ *            P2
+ */
+/* clang-format off */
+FIXTURE_VARIANT_ADD(unix_socket, allow_with_parent_domain_connect_to_parent) {
+	/* clang-format on */
+	.domain_both = false,
+	.domain_parent = true,
+	.domain_child = false,
+	.connect_to_parent = true,
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(unix_socket, deny_with_parent_domain_connect_to_child) {
+	/* clang-format on */
+	.domain_both = false,
+	.domain_parent = true,
+	.domain_child = false,
+	.connect_to_parent = false,
+};
+
+/*
+ *        Parent + child domain (siblings)
+ * .------.
+ * |  P1  ---.          P1 -> P2 : deny
+ * '------'   \         P2 -> P1 : deny
+ *         .---'--.
+ *         |  P2  |
+ *         '------'
+ */
+/* clang-format off */
+FIXTURE_VARIANT_ADD(unix_socket, deny_with_sibling_domain_connect_to_parent) {
+	/* clang-format on */
+	.domain_both = false,
+	.domain_parent = true,
+	.domain_child = true,
+	.connect_to_parent = true,
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(unix_socket, deny_with_sibling_domain_connect_to_child) {
+	/* clang-format on */
+	.domain_both = false,
+	.domain_parent = true,
+	.domain_child = true,
+	.connect_to_parent = false,
+};
+
+/*
+ *         Same domain (inherited)
+ * .-------------.
+ * | P1----.     |      P1 -> P2 : allow
+ * |        \    |      P2 -> P1 : allow
+ * |         '   |
+ * |         P2  |
+ * '-------------'
+ */
+/* clang-format off */
+FIXTURE_VARIANT_ADD(unix_socket, allow_inherited_domain_connect_to_parent) {
+	/* clang-format on */
+	.domain_both = true,
+	.domain_parent = false,
+	.domain_child = false,
+	.connect_to_parent = true,
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(unix_socket, allow_inherited_domain_connect_to_child) {
+	/* clang-format on */
+	.domain_both = true,
+	.domain_parent = false,
+	.domain_child = false,
+	.connect_to_parent = false,
+};
+
+/*
+ *         Inherited + child domain
+ * .-----------------.
+ * |  P1----.        |  P1 -> P2 : allow
+ * |         \       |  P2 -> P1 : deny
+ * |        .-'----. |
+ * |        |  P2  | |
+ * |        '------' |
+ * '-----------------'
+ */
+/* clang-format off */
+FIXTURE_VARIANT_ADD(unix_socket, deny_nested_domain_connect_to_parent) {
+	/* clang-format on */
+	.domain_both = true,
+	.domain_parent = false,
+	.domain_child = true,
+	.connect_to_parent = true,
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(unix_socket, allow_nested_domain_connect_to_child) {
+	/* clang-format on */
+	.domain_both = true,
+	.domain_parent = false,
+	.domain_child = true,
+	.connect_to_parent = false,
+};
+
+/*
+ *         Inherited + parent domain
+ * .-----------------.
+ * |.------.         |  P1 -> P2 : deny
+ * ||  P1  ----.     |  P2 -> P1 : allow
+ * |'------'    \    |
+ * |             '   |
+ * |             P2  |
+ * '-----------------'
+ */
+/* clang-format off */
+FIXTURE_VARIANT_ADD(unix_socket, allow_with_nested_and_parent_domain_connect_to_parent) {
+	/* clang-format on */
+	.domain_both = true,
+	.domain_parent = true,
+	.domain_child = false,
+	.connect_to_parent = true,
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(unix_socket, deny_with_nested_and_parent_domain_connect_to_child) {
+	/* clang-format on */
+	.domain_both = true,
+	.domain_parent = true,
+	.domain_child = false,
+	.connect_to_parent = false,
+};
+
+/*
+ *         Inherited + parent and child domain (siblings)
+ * .-----------------.
+ * | .------.        |  P1 -> P2 : deny
+ * | |  P1  .        |  P2 -> P1 : deny
+ * | '------'\       |
+ * |          \      |
+ * |        .--'---. |
+ * |        |  P2  | |
+ * |        '------' |
+ * '-----------------'
+ */
+/* clang-format off */
+FIXTURE_VARIANT_ADD(unix_socket, deny_with_forked_domain_connect_to_parent) {
+	/* clang-format on */
+	.domain_both = true,
+	.domain_parent = true,
+	.domain_child = true,
+	.connect_to_parent = true,
+};
+
+/* clang-format off */
+FIXTURE_VARIANT_ADD(unix_socket, deny_with_forked_domain_connect_to_child) {
+	/* clang-format on */
+	.domain_both = true,
+	.domain_parent = true,
+	.domain_child = true,
+	.connect_to_parent = false,
+};
+
+/*
+ * Test unix_stream_connect()  and unix_may_send() for parent and child,
+ * when they have scoped domain or no domain.
+ */
+TEST_F(unix_socket, abstract_unix_socket)
+{
+	struct service_fixture stream_address, dgram_address;
+	pid_t child;
+	bool can_connect_to_parent, can_connect_to_child;
+	int err, err_dgram, status;
+	int pipe_child[2], pipe_parent[2];
+	char buf_parent;

For all TEST() and TEST_F(), in this patch series and the signal one, we
need to first drop capabilities:

drop_caps(_metadata);

+
+	memset(&stream_address, 0, sizeof(stream_address));
+	memset(&dgram_address, 0, sizeof(dgram_address));
+	set_unix_address(&stream_address, 0);
+	set_unix_address(&dgram_address, 1);
+	/*
+	 * can_connect_to_child is true if a parent process can connect to its
+	 * child process. The parent process is not isolated from the child
+	 * with a dedicated Landlock domain.
+	 */
+	can_connect_to_child = !variant->domain_parent;
+	/*
+	 * can_connect_to_parent is true if a child process can connect to its
+	 * parent process. This depends on the child process is not isolated from
+	 * the parent with a dedicated Landlock domain.
+	 */
+	can_connect_to_parent = !variant->domain_child;
+
+	ASSERT_EQ(0, pipe2(pipe_child, O_CLOEXEC));
+	ASSERT_EQ(0, pipe2(pipe_parent, O_CLOEXEC));
+	if (variant->domain_both) {
+		create_unix_domain(_metadata);
+		if (!__test_passed(_metadata))
+			return;
+	}
+
+	child = fork();
+	ASSERT_LE(0, child);
+	if (child == 0) {
+		char buf_child;
+
+		ASSERT_EQ(0, close(pipe_parent[1]));
+		ASSERT_EQ(0, close(pipe_child[0]));
+		if (variant->domain_child)
+			create_unix_domain(_metadata);
+
+		/* Waits for the parent to be in a domain, if any. */
+		ASSERT_EQ(1, read(pipe_parent[0], &buf_child, 1));
+
+		if (variant->connect_to_parent) {
+			int client, dgram_client;

It looks like you missed some of my previous reviews (e.g. variable
names).  Please read back again *all* my reviews/emails for at least the
last two versions.

+
+			client = socket(AF_UNIX, SOCK_STREAM, 0);
+			dgram_client = socket(AF_UNIX, SOCK_DGRAM, 0);
+

+TEST_F(outside_socket, socket_with_different_domain)
+{
+	pid_t child;
+	int err, status;
+	int pipe_child[2], pipe_parent[2];
+	char buf_parent;
+	struct service_fixture address, transit_address;
+
+	ASSERT_EQ(0, pipe2(pipe_child, O_CLOEXEC));
+	ASSERT_EQ(0, pipe2(pipe_parent, O_CLOEXEC));
+
+	memset(&transit_address, 0, sizeof(transit_address));
+	memset(&address, 0, sizeof(address));
+	set_unix_address(&transit_address, 0);
+	set_unix_address(&address, 1);
+
+	child = fork();
+	ASSERT_LE(0, child);
+	if (child == 0) {
+		char buf_child;
+		int stream_server, client;
+
+		ASSERT_EQ(0, close(pipe_parent[1]));
+		ASSERT_EQ(0, close(pipe_child[0]));
+
+		/* client always has domain */
+		create_unix_domain(_metadata);
+
+		if (variant->domain_server_socket) {
+			int data_socket;
+			int fd_sock = socket(AF_UNIX, variant->type, 0);
+
+			ASSERT_NE(-1, fd_sock);
+
+			stream_server = socket(AF_UNIX, SOCK_STREAM, 0);
+
+			ASSERT_NE(-1, stream_server);
+			ASSERT_EQ(0, bind(stream_server,
+					  &transit_address.unix_addr,
+					  transit_address.unix_addr_len));
+			ASSERT_EQ(0, listen(stream_server, backlog));
+
+			ASSERT_EQ(1, write(pipe_child[1], ".", 1));
+
+			data_socket = accept(stream_server, NULL, NULL);
+
+			ASSERT_EQ(0, send_fd(data_socket, fd_sock));
+			ASSERT_EQ(0, close(fd_sock));
+			ASSERT_EQ(0, close(stream_server));
+		}
+
+		client = socket(AF_UNIX, variant->type, 0);
+		ASSERT_NE(-1, client);
+		/* wait for parent signal for connection */
+		ASSERT_EQ(1, read(pipe_parent[0], &buf_child, 1));
+
+		err = connect(client, &address.unix_addr,
+			      address.unix_addr_len);
+		if (!variant->domain_server_socket) {
+			EXPECT_EQ(-1, err);
+			EXPECT_EQ(EPERM, errno);
+		} else {
+			EXPECT_EQ(0, err);
+		}
+		ASSERT_EQ(0, close(client));
+		_exit(_metadata->exit_code);
+		return;
+	}
+	int server_socket;

Variable declarations go at the top of the scope where other variable
are declared.

+
+	ASSERT_EQ(0, close(pipe_child[1]));
+	ASSERT_EQ(0, close(pipe_parent[0]));
+
+	if (!variant->domain_server_socket) {
+		server_socket = socket(AF_UNIX, variant->type, 0);
+	} else {
+		int cli = socket(AF_UNIX, SOCK_STREAM, 0);
+
+		ASSERT_NE(-1, cli);
+		ASSERT_EQ(1, read(pipe_child[0], &buf_parent, 1));
+		ASSERT_EQ(0, connect(cli, &transit_address.unix_addr,
+				     transit_address.unix_addr_len));
+
+		server_socket = recv_fd(cli);
+		ASSERT_LE(0, server_socket);
+		ASSERT_EQ(0, close(cli));
+	}
+
+	ASSERT_NE(-1, server_socket);
+
+	if (variant->domain_server)
+		create_unix_domain(_metadata);
+
+	ASSERT_EQ(0, bind(server_socket, &address.unix_addr,
+			  address.unix_addr_len));
+	if (variant->type == SOCK_STREAM)
+		ASSERT_EQ(0, listen(server_socket, backlog));
+	/* signal to child that parent is listening */
+	ASSERT_EQ(1, write(pipe_parent[1], ".", 1));
+
+	ASSERT_EQ(child, waitpid(child, &status, 0));
+	ASSERT_EQ(0, close(server_socket));
+
+	if (WIFSIGNALED(status) || !WIFEXITED(status) ||
+	    WEXITSTATUS(status) != EXIT_SUCCESS)
+		_metadata->exit_code = KSFT_FAIL;
+}
+
+TEST_HARNESS_MAIN
-- 
2.34.1