netdev - Re: [RFC PATCH v2 6/9] selftests/landlock: Test listening without explicit bind restriction

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Message-ID: <58b328fc-aa98-c4f1-eb11-2d59e50ec407@huawei-partners.com>
Date: Tue, 20 Aug 2024 16:46:17 +0300
From: Mikhail Ivanov <ivanov.mikhail1@...wei-partners.com>
To: Günther Noack <gnoack@...gle.com>
CC: <mic@...ikod.net>, <willemdebruijn.kernel@...il.com>,
	<gnoack3000@...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 6/9] selftests/landlock: Test listening without
 explicit bind restriction

8/20/2024 4:02 PM, Günther Noack wrote:
> On Wed, Aug 14, 2024 at 11:01:48AM +0800, Mikhail Ivanov wrote:
>> Test scenarios where listen(2) call without explicit bind(2) is allowed
>> and forbidden.
>>
>> Signed-off-by: Mikhail Ivanov <ivanov.mikhail1@...wei-partners.com>
>> ---
>>   tools/testing/selftests/landlock/net_test.c | 83 +++++++++++++++++++++
>>   1 file changed, 83 insertions(+)
>>
>> diff --git a/tools/testing/selftests/landlock/net_test.c b/tools/testing/selftests/landlock/net_test.c
>> index 551891b18b7a..92c042349596 100644
>> --- a/tools/testing/selftests/landlock/net_test.c
>> +++ b/tools/testing/selftests/landlock/net_test.c
>> @@ -1851,6 +1851,89 @@ TEST_F(port_specific, bind_connect_zero)
>>   	EXPECT_EQ(0, close(bind_fd));
>>   }
>>   
>> +TEST_F(port_specific, listen_without_bind_allowed)
>> +{
>> +	if (variant->sandbox == TCP_SANDBOX) {
>> +		const struct landlock_ruleset_attr ruleset_attr = {
>> +			.handled_access_net = LANDLOCK_ACCESS_NET_BIND_TCP |
>> +					      LANDLOCK_ACCESS_NET_LISTEN_TCP
>> +		};
>> +		const struct landlock_net_port_attr tcp_listen_zero = {
>> +			.allowed_access = LANDLOCK_ACCESS_NET_LISTEN_TCP,
>> +			.port = 0,
>> +		};
>> +		int ruleset_fd;
>> +
>> +		ruleset_fd = landlock_create_ruleset(&ruleset_attr,
>> +						     sizeof(ruleset_attr), 0);
>> +		ASSERT_LE(0, ruleset_fd);
>> +
>> +		/*
>> +		 * Allow listening without explicit bind
>> +		 * (cf. landlock_net_port_attr).
>> +		 */
>> +		EXPECT_EQ(0,
>> +			  landlock_add_rule(ruleset_fd, LANDLOCK_RULE_NET_PORT,
>> +					    &tcp_listen_zero, 0));
>> +
>> +		enforce_ruleset(_metadata, ruleset_fd);
>> +		EXPECT_EQ(0, close(ruleset_fd));
>> +	}
>> +	int listen_fd, connect_fd;
>> +	__u64 port;
>> +
>> +	listen_fd = socket_variant(&self->srv0);
>> +	ASSERT_LE(0, listen_fd);
>> +
>> +	connect_fd = socket_variant(&self->srv0);
>> +	ASSERT_LE(0, connect_fd);
>> +	/*
>> +	 * Allow listen(2) to select a random port for the socket,
>> +	 * since bind(2) wasn't called.
>> +	 */
>> +	EXPECT_EQ(0, listen_variant(listen_fd, backlog));
>> +
>> +	/* Connects on the binded port. */
>> +	port = get_binded_port(listen_fd, &variant->prot);
> 
> Please rename "binded" to "bound" when you come across it.

Can I do such refactoring in the 3/9 patch?

> 
> 
>> +	EXPECT_NE(0, port);
>> +	set_port(&self->srv0, port);
>> +	EXPECT_EQ(0, connect_variant(connect_fd, &self->srv0));
>> +
>> +	EXPECT_EQ(0, close(connect_fd));
>> +	EXPECT_EQ(0, close(listen_fd));
>> +}
>> +
>> +TEST_F(port_specific, listen_without_bind_denied)
>> +{
>> +	if (variant->sandbox == TCP_SANDBOX) {
>> +		const struct landlock_ruleset_attr ruleset_attr = {
>> +			.handled_access_net = LANDLOCK_ACCESS_NET_LISTEN_TCP
>> +		};
>> +		int ruleset_fd;
>> +
>> +		ruleset_fd = landlock_create_ruleset(&ruleset_attr,
>> +						     sizeof(ruleset_attr), 0);
>> +		ASSERT_LE(0, ruleset_fd);
>> +
>> +		/* Deny listening. */
>> +		enforce_ruleset(_metadata, ruleset_fd);
>> +		EXPECT_EQ(0, close(ruleset_fd));
>> +	}
>> +	int listen_fd, ret;
>> +
>> +	listen_fd = socket_variant(&self->srv0);
>> +	ASSERT_LE(0, listen_fd);
>> +
>> +	/* Checks that listening without explicit binding is prohibited. */
>> +	ret = listen_variant(listen_fd, backlog);
>> +	if (is_restricted(&variant->prot, variant->sandbox)) {
>> +		/* Denied by Landlock. */
>> +		EXPECT_EQ(-EACCES, ret);
>> +	} else {
>> +		EXPECT_EQ(0, ret);
>> +	}
>> +}
>> +
>>   TEST_F(port_specific, port_1023)
>>   {
>>   	int bind_fd, connect_fd, ret;
>> -- 
>> 2.34.1
>>