netdev - Re: [RFC PATCH v3 11/19] selftests/landlock: Test unsupported protocol restriction

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Message-ID: <810a169f-4d79-8a59-d58a-bba496b5f68a@huawei-partners.com>
Date: Wed, 18 Sep 2024 16:36:57 +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 v3 11/19] selftests/landlock: Test unsupported
 protocol restriction

On 9/18/2024 3:54 PM, Günther Noack wrote:
> On Wed, Sep 04, 2024 at 06:48:16PM +0800, Mikhail Ivanov wrote:
>> Add test validating that Landlock doesn't wrongfully
>> return EACCES for unsupported address family and protocol.
>>
>> Signed-off-by: Mikhail Ivanov <ivanov.mikhail1@...wei-partners.com>
>> ---
>> Changes since v1:
>> * Adds socket(2) error code check when ruleset is not established.
>> * Tests unsupported family for error code consistency.
>> * Renames test to `unsupported_af_and_prot`.
>> * Refactors commit title and message.
>> * Minor fixes.
>> ---
>>   .../testing/selftests/landlock/socket_test.c  | 47 +++++++++++++++++++
>>   1 file changed, 47 insertions(+)
>>
>> diff --git a/tools/testing/selftests/landlock/socket_test.c b/tools/testing/selftests/landlock/socket_test.c
>> index 047603abc5a7..ff5ace711697 100644
>> --- a/tools/testing/selftests/landlock/socket_test.c
>> +++ b/tools/testing/selftests/landlock/socket_test.c
>> @@ -581,4 +581,51 @@ TEST_F(prot_outside_range, add_rule)
>>   	ASSERT_EQ(0, close(ruleset_fd));
>>   }
>>   
>> +TEST(unsupported_af_and_prot)
> 
> Nit: If I am reading this test correctly, the point is to make sure that for
> unsuported (EAFNOSUPPORT and ESOCKTNOSUPPORT) combinations of "family" and
> "type", socket(2) returns the same error code, independent of whether that
> combination is restricted with Landlock or not.  Maybe we could make it more
> clear from the test name or a brief docstring that this is about error code
> compatibility when calling socket() under from within a Landlock domain?

Agreed, thanks for the nit! I think that docstring would be more
appropriate here (similar to the kernel_socket test).

> 
>> +{
>> +	const struct landlock_ruleset_attr ruleset_attr = {
>> +		.handled_access_socket = LANDLOCK_ACCESS_SOCKET_CREATE,
>> +	};
>> +	struct landlock_socket_attr socket_af_unsupported = {
>> +		.allowed_access = LANDLOCK_ACCESS_SOCKET_CREATE,
>> +		.family = AF_UNSPEC,
>> +		.type = SOCK_STREAM,
>> +	};
>> +	struct landlock_socket_attr socket_prot_unsupported = {
>                                             ^^^^
> Here and in the test name: Should this say "type" instead of "prot"?
> It seems that the part that is unsupported here is the socket(2) "type"
> argument, not the "protocol" argument?

You're right, this naming is more more suitable for the EPROTONOSUPPORT.
I'll extend this test by adding a separate check for this error code.

> 
>> +		.allowed_access = LANDLOCK_ACCESS_SOCKET_CREATE,
>> +		.family = AF_UNIX,
>> +		.type = SOCK_PACKET,
>> +	};
>> +	int ruleset_fd;
>> +
>> +	/* Tries to create a socket when ruleset is not established. */
>> +	ASSERT_EQ(EAFNOSUPPORT, test_socket(AF_UNSPEC, SOCK_STREAM, 0));
>> +	ASSERT_EQ(ESOCKTNOSUPPORT, test_socket(AF_UNIX, SOCK_PACKET, 0));
>> +
>> +	ruleset_fd =
>> +		landlock_create_ruleset(&ruleset_attr, sizeof(ruleset_attr), 0);
>> +	ASSERT_LE(0, ruleset_fd);
>> +
>> +	EXPECT_EQ(0, landlock_add_rule(ruleset_fd, LANDLOCK_RULE_SOCKET,
>> +				       &socket_af_unsupported, 0));
>> +	EXPECT_EQ(0, landlock_add_rule(ruleset_fd, LANDLOCK_RULE_SOCKET,
>> +				       &socket_prot_unsupported, 0));
>> +	enforce_ruleset(_metadata, ruleset_fd);
>> +	ASSERT_EQ(0, close(ruleset_fd));
>> +
>> +	/* Tries to create a socket when protocols are allowed. */
>> +	EXPECT_EQ(EAFNOSUPPORT, test_socket(AF_UNSPEC, SOCK_STREAM, 0));
>> +	EXPECT_EQ(ESOCKTNOSUPPORT, test_socket(AF_UNIX, SOCK_PACKET, 0));
>> +
>> +	ruleset_fd =
>> +		landlock_create_ruleset(&ruleset_attr, sizeof(ruleset_attr), 0);
>> +	ASSERT_LE(0, ruleset_fd);
>> +	enforce_ruleset(_metadata, ruleset_fd);
>> +	ASSERT_EQ(0, close(ruleset_fd));
>> +
>> +	/* Tries to create a socket when protocols are restricted. */
>> +	EXPECT_EQ(EAFNOSUPPORT, test_socket(AF_UNSPEC, SOCK_STREAM, 0));
>> +	EXPECT_EQ(ESOCKTNOSUPPORT, test_socket(AF_UNIX, SOCK_PACKET, 0));
>> +}
>> +
>>   TEST_HARNESS_MAIN
>> -- 
>> 2.34.1
>>