netdev - Re: [PATCH 2/2] selftests/landlock: Create 'listen_zero', 'deny_listen

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Date: Mon, 13 May 2024 15:18:32 +0300
From: Ivanov Mikhail <ivanov.mikhail1@...wei-partners.com>
To: Mickaël Salaün <mic@...ikod.net>
CC: <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>,
	Günther Noack <gnoack@...gle.com>
Subject: Re: [PATCH 2/2] selftests/landlock: Create 'listen_zero',
 'deny_listen_zero' tests



4/30/2024 4:36 PM, Mickaël Salaün wrote:
> The subject should be something like:
> "selftests/landlock: Test listening on socket without binding"

thanks, will be fixed.

> 
> On Mon, Apr 08, 2024 at 05:47:47PM +0800, Ivanov Mikhail wrote:
>> Suggested code test scenarios where listen(2) call without explicit
>> bind(2) is allowed and forbidden.
>>
>> Signed-off-by: Ivanov Mikhail <ivanov.mikhail1@...wei-partners.com>
>> Reviewed-by: Konstantin Meskhidze <konstantin.meskhidze@...wei.com>
>> ---
>>   tools/testing/selftests/landlock/net_test.c | 89 +++++++++++++++++++++
>>   1 file changed, 89 insertions(+)
>>
>> diff --git a/tools/testing/selftests/landlock/net_test.c b/tools/testing/selftests/landlock/net_test.c
>> index 936cfc879f1d..6d6b5aef387f 100644
>> --- a/tools/testing/selftests/landlock/net_test.c
>> +++ b/tools/testing/selftests/landlock/net_test.c
>> @@ -1714,6 +1714,95 @@ TEST_F(port_specific, bind_connect_zero)
>>   	EXPECT_EQ(0, close(bind_fd));
>>   }
>>   
>> +TEST_F(port_specific, listen_zero)
>> +{
>> +	int listen_fd, connect_fd;
>> +	uint16_t port;
>> +
>> +	/* Adds a rule layer with bind actions. */
>> +	if (variant->sandbox == TCP_SANDBOX) {
>> +		const struct landlock_ruleset_attr ruleset_attr = {
>> +			.handled_access_net = LANDLOCK_ACCESS_NET_BIND_TCP,
>> +		};
>> +		const struct landlock_net_port_attr tcp_bind_zero = {
>> +			.allowed_access = LANDLOCK_ACCESS_NET_BIND_TCP,
>> +			.port = 0,
>> +		};
>> +		int ruleset_fd;
>> +
>> +		ruleset_fd = landlock_create_ruleset(&ruleset_attr,
>> +						     sizeof(ruleset_attr), 0);
>> +		ASSERT_LE(0, ruleset_fd);
>> +
>> +		/* Checks zero port value on bind action. */
>> +		EXPECT_EQ(0,
>> +			  landlock_add_rule(ruleset_fd, LANDLOCK_RULE_NET_PORT,
>> +					    &tcp_bind_zero, 0));
>> +
>> +		enforce_ruleset(_metadata, ruleset_fd);
>> +		EXPECT_EQ(0, close(ruleset_fd));
>> +	}
>> +
>> +	listen_fd = socket_variant(&self->srv0);
>> +	ASSERT_LE(0, listen_fd);
>> +
>> +	connect_fd = socket_variant(&self->srv0);
>> +	ASSERT_LE(0, listen_fd);
>> +	/*
>> +	 * Allow listen(2) to select a random port for the socket,
>> +	 * since bind(2) wasn't called.
>> +	 */
>> +	EXPECT_EQ(0, listen(listen_fd, backlog));
>> +
>> +	/* Sets binded (by listen(2)) port for both protocol families. */
>> +	port = get_binded_port(listen_fd, &variant->prot);
>> +	EXPECT_NE(0, port);
>> +	set_port(&self->srv0, port);
>> +
>> +	/* Connects on the binded port. */
>> +	EXPECT_EQ(0, connect_variant(connect_fd, &self->srv0));
>> +
>> +	EXPECT_EQ(0, close(listen_fd));
>> +	EXPECT_EQ(0, close(connect_fd));
>> +}
>> +
>> +TEST_F(port_specific, deny_listen_zero)
>> +{
>> +	int listen_fd, ret;
>> +
>> +	/* Adds a rule layer with bind actions. */
>> +	if (variant->sandbox == TCP_SANDBOX) {
>> +		const struct landlock_ruleset_attr ruleset_attr = {
>> +			.handled_access_net = LANDLOCK_ACCESS_NET_BIND_TCP,
>> +		};
>> +		int ruleset_fd;
>> +
>> +		ruleset_fd = landlock_create_ruleset(&ruleset_attr,
>> +						     sizeof(ruleset_attr), 0);
>> +		ASSERT_LE(0, ruleset_fd);
>> +
>> +		/* Forbid binding to any port. */
>> +		enforce_ruleset(_metadata, ruleset_fd);
>> +		EXPECT_EQ(0, close(ruleset_fd));
>> +	}
>> +
>> +	listen_fd = socket_variant(&self->srv0);
>> +	ASSERT_LE(0, listen_fd);
>> +	/*
> 
> nit: Extra space

will be fixed

> 
>> +	 * Check that listen(2) call is prohibited without first calling bind(2).
> 
> This should fit in 80 columns.

will be fixed

> 
>> +	 */
>> +	ret = listen(listen_fd, backlog);
>> +	if (is_restricted(&variant->prot, variant->sandbox)) {
>> +		/* Denied by Landlock. */
>> +		EXPECT_NE(0, ret);
>> +		EXPECT_EQ(EACCES, errno);
>> +	} else {
>> +		EXPECT_EQ(0, ret);
>> +	}
>> +
>> +	EXPECT_EQ(0, close(listen_fd));
>> +}
> 
> These tests look good!
> 
>> +
>>   TEST_F(port_specific, bind_connect_1023)
>>   {
>>   	int bind_fd, connect_fd, ret;
>> -- 
>> 2.34.1
>>
>>