[RFC PATCH v4 12/19] selftests/landlock: Test socketpair(2) restriction

[Mikhail Ivanov]

On 11/22/2025 1:16 PM, Günther Noack wrote:
> On Tue, Nov 18, 2025 at 09:46:32PM +0800, Mikhail Ivanov wrote:
>> diff --git a/tools/testing/selftests/landlock/socket_test.c b/tools/testing/selftests/landlock/socket_test.c
>> index e22e10edb103..d1a004c2e0f5 100644
>> --- a/tools/testing/selftests/landlock/socket_test.c
>> +++ b/tools/testing/selftests/landlock/socket_test.c
>> @@ -866,4 +866,59 @@ TEST_F(tcp_protocol, alias_restriction)
>>   	}
>>   }
>>   
>> +static int test_socketpair(int family, int type, int protocol)
>> +{
>> +	int fds[2];
>> +	int err;
>> +
>> +	err = socketpair(family, type | SOCK_CLOEXEC, protocol, fds);
>> +	if (err)
>> +		return errno;
>> +	/*
>> +	 * Mixing error codes from close(2) and socketpair(2) should not lead to
>> +	 * any (access type) confusion for this test.
>> +	 */
>> +	if (close(fds[0]) != 0)
>> +		return errno;
>> +	if (close(fds[1]) != 0)
>> +		return errno;
> 
> Very minor nit: the function leaks an FD if it returns early after the
> first close() call failed.  (Highly unlikely to happen though.)

Yeah, but AFAIK fd[0] may be leaked anyway if close() fails. Anyway
this shouldn't be an issue for tests.

> 
>> +	return 0;
>> +}
>> +
>> +TEST_F(mini, socketpair)
>> +{
>> +	const struct landlock_ruleset_attr ruleset_attr = {
>> +		.handled_access_socket = LANDLOCK_ACCESS_SOCKET_CREATE,
>> +	};
>> +	const struct landlock_socket_attr unix_socket_create = {
>> +		.allowed_access = LANDLOCK_ACCESS_SOCKET_CREATE,
>> +		.family = AF_UNIX,
>> +		.type = SOCK_STREAM,
>> +		.protocol = 0,
>> +	};
>> +	int ruleset_fd;
>> +
>> +	/* Tries to create socket when ruleset is not established. */
>> +	ASSERT_EQ(0, test_socketpair(AF_UNIX, SOCK_STREAM, 0));
>> +	ruleset_fd =
>> +		landlock_create_ruleset(&ruleset_attr, sizeof(ruleset_attr), 0);
>> +	ASSERT_LE(0, ruleset_fd);
>> +
>> +	ASSERT_EQ(0, landlock_add_rule(ruleset_fd, LANDLOCK_RULE_SOCKET,
>> +				       &unix_socket_create, 0));
>> +	enforce_ruleset(_metadata, ruleset_fd);
>> +	ASSERT_EQ(0, close(ruleset_fd));
>> +
>> +	/* Tries to create socket when protocol is allowed */
>> +	EXPECT_EQ(0, test_socketpair(AF_UNIX, SOCK_STREAM, 0));
>> +
>> +	ruleset_fd =
>> +		landlock_create_ruleset(&ruleset_attr, sizeof(ruleset_attr), 0);
> 
> You may want to check that landlock_create_ruleset() succeeded here:
> 
> ASSERT_LE(0, ruleset_fd)

thanks, I'll fix it.

> 
>> +	enforce_ruleset(_metadata, ruleset_fd);
>> +	ASSERT_EQ(0, close(ruleset_fd));
>> +
>> +	/* Tries to create socket when protocol is restricted. */
>> +	EXPECT_EQ(EACCES, test_socketpair(AF_UNIX, SOCK_STREAM, 0));
>> +}
>> +
>>   TEST_HARNESS_MAIN
>> -- 
>> 2.34.1
>>
> 
> Otherwise, looks good.
> –Günther