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

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Message-ID: <20240430.ohruCa7giToo@digikod.net>
Date: Tue, 30 Apr 2024 15:36:43 +0200
From: Mickaël Salaün <mic@...ikod.net>
To: Ivanov Mikhail <ivanov.mikhail1@...wei-partners.com>
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

The subject should be something like:
"selftests/landlock: Test listening on socket without binding"

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

> +	 * Check that listen(2) call is prohibited without first calling bind(2).

This should fit in 80 columns.

> +	 */
> +	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
> 
>