netdev - Re: [RFC PATCH v2 8/9] selftests/landlock: Test changing socket backlog with listen(2)

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Message-ID: <70ae6422-4e8c-465f-9bbf-5ff4df52a057@huawei-partners.com>
Date: Sat, 5 Oct 2024 20:29:34 +0300
From: Mikhail Ivanov <ivanov.mikhail1@...wei-partners.com>
To: Günther Noack <gnoack3000@...il.com>
CC: <mic@...ikod.net>, <willemdebruijn.kernel@...il.com>,
	<linux-security-module@...r.kernel.org>, <netdev@...r.kernel.org>,
	<netfilter-devel@...r.kernel.org>, <yusongping@...wei.com>,
	<artem.kuzin@...wei.com>, <konstantin.meskhidze@...wei.com>
Subject: Re: [RFC PATCH v2 8/9] selftests/landlock: Test changing socket
 backlog with listen(2)

On 10/5/2024 7:57 PM, Günther Noack wrote:
> On Wed, Aug 14, 2024 at 11:01:50AM +0800, Mikhail Ivanov wrote:
>> listen(2) can be used to change length of the pending connections queue
>> of the listening socket. Such scenario shouldn't be restricted by Landlock
>> since socket doesn't change its state.
> 
> Yes, this behavior makes sense to me as well. 👍 __inet_listen_sk()
> only changes sk->sk_max_ack_backlog when listen() gets called a second
> time.
> 
>> * Implement test that validates this case.
>>
>> Signed-off-by: Mikhail Ivanov <ivanov.mikhail1@...wei-partners.com>
>> ---
>>   tools/testing/selftests/landlock/net_test.c | 26 +++++++++++++++++++++
>>   1 file changed, 26 insertions(+)
>>
>> diff --git a/tools/testing/selftests/landlock/net_test.c b/tools/testing/selftests/landlock/net_test.c
>> index 6831d8a2e9aa..dafc433a0068 100644
>> --- a/tools/testing/selftests/landlock/net_test.c
>> +++ b/tools/testing/selftests/landlock/net_test.c
>> @@ -1768,6 +1768,32 @@ TEST_F(ipv4_tcp, with_fs)
>>   	EXPECT_EQ(-EACCES, bind_variant(bind_fd, &self->srv1));
>>   }
>>   
>> +TEST_F(ipv4_tcp, double_listen)
>> +{
>> +	const struct landlock_ruleset_attr ruleset_attr = {
>> +		.handled_access_net = LANDLOCK_ACCESS_NET_LISTEN_TCP,
>> +	};
>> +	int ruleset_fd;
>> +	int listen_fd;
>> +
>> +	listen_fd = socket_variant(&self->srv0);
>> +	ASSERT_LE(0, listen_fd);
>> +
>> +	EXPECT_EQ(0, bind_variant(listen_fd, &self->srv0));
>> +	EXPECT_EQ(0, listen_variant(listen_fd, backlog));
>> +
>> +	ruleset_fd =
>> +		landlock_create_ruleset(&ruleset_attr, sizeof(ruleset_attr), 0);
>> +	ASSERT_LE(0, ruleset_fd);
>> +
>> +	/* Denies listen. */
>> +	enforce_ruleset(_metadata, ruleset_fd);
>> +	EXPECT_EQ(0, close(ruleset_fd));
>> +
>> +	/* Tries to change backlog value of listening socket. */
>> +	EXPECT_EQ(0, listen_variant(listen_fd, backlog + 1));
> 
> For test clarity: Without reading the commit message, I believe it
> might not be obvious to the reader *why* the second listen() is
> supposed to work.  This might be worth a comment.

Ofc, thanks!

> 
>> +}
>> +
>>   FIXTURE(port_specific)
>>   {
>>   	struct service_fixture srv0;
>> -- 
>> 2.34.1
>>
> 
> Reviewed-by: Günther Noack <gnoack3000@...il.com>