[RFC PATCH v3 13/19] selftests/landlock: Test packet protocol alias

[Mikhail Ivanov]

On 9/18/2024 4:33 PM, Günther Noack wrote:
> On Wed, Sep 04, 2024 at 06:48:18PM +0800, Mikhail Ivanov wrote:
>> (AF_INET, SOCK_PACKET) is an alias for (AF_PACKET, SOCK_PACKET)
>> (Cf. __sock_create). Landlock shouldn't restrict one pair if the other
>> was allowed. Add `packet_protocol` fixture and test to
>> validate these scenarios.
>>
>> Signed-off-by: Mikhail Ivanov <ivanov.mikhail1 at huawei-partners.com>
>> ---
>>   .../testing/selftests/landlock/socket_test.c  | 75 ++++++++++++++++++-
>>   1 file changed, 74 insertions(+), 1 deletion(-)
>>
>> diff --git a/tools/testing/selftests/landlock/socket_test.c b/tools/testing/selftests/landlock/socket_test.c
>> index 23698b8c2f4d..8fc507bf902a 100644
>> --- a/tools/testing/selftests/landlock/socket_test.c
>> +++ b/tools/testing/selftests/landlock/socket_test.c
>> @@ -7,7 +7,7 @@
>>   
>>   #define _GNU_SOURCE
>>   
>> -#include "landlock.h"
>> +#include <linux/landlock.h>
>>   #include <linux/pfkeyv2.h>
>>   #include <linux/kcm.h>
>>   #include <linux/can.h>
>> @@ -665,4 +665,77 @@ TEST(kernel_socket)
>>   	EXPECT_EQ(0, test_socket(AF_SMC, SOCK_STREAM, 0));
>>   }
>>   
>> +FIXTURE(packet_protocol)
>> +{
>> +	struct protocol_variant prot_allowed, prot_tested;
>> +};
>> +
>> +FIXTURE_VARIANT(packet_protocol)
>> +{
>> +	bool packet;
>> +};
>> +
>> +FIXTURE_SETUP(packet_protocol)
>> +{
>> +	self->prot_allowed.type = self->prot_tested.type = SOCK_PACKET;
>> +
>> +	self->prot_allowed.family = variant->packet ? AF_PACKET : AF_INET;
>> +	self->prot_tested.family = variant->packet ? AF_INET : AF_PACKET;
> 
> Nit: You might as well write these resulting prot_allowed and prot_tested struct
> values out in the two fixture variants.  It's one layer of indirection less and
> clarity trumps deduplication in tests, IMHO.  Fine either way though.

Agreed, thanks!

> 
> 
>> +
>> +	/* Packet protocol requires NET_RAW to be set (Cf. packet_create). */
>> +	set_cap(_metadata, CAP_NET_RAW);
>> +};
>> +
>> +FIXTURE_TEARDOWN(packet_protocol)
>> +{
>> +	clear_cap(_metadata, CAP_NET_RAW);
>> +}
>> +
>> +/* clang-format off */
>> +FIXTURE_VARIANT_ADD(packet_protocol, packet_allows_inet) {
>> +	/* clang-format on */
>> +	.packet = true,
>> +};
>> +
>> +/* clang-format off */
>> +FIXTURE_VARIANT_ADD(packet_protocol, inet_allows_packet) {
>> +	/* clang-format on */
>> +	.packet = false,
>> +};
>> +
>> +TEST_F(packet_protocol, alias_restriction)
>> +{
>> +	const struct landlock_ruleset_attr ruleset_attr = {
>> +		.handled_access_socket = LANDLOCK_ACCESS_SOCKET_CREATE,
>> +	};
>> +	struct landlock_socket_attr packet_socket_create = {
>> +		.allowed_access = LANDLOCK_ACCESS_SOCKET_CREATE,
>> +		.family = self->prot_allowed.family,
>> +		.type = self->prot_allowed.type,
>> +	};
>> +	int ruleset_fd;
>> +
>> +	/*
>> +	 * Checks that packet socket is created sucessfuly without
> 
> Typo nit: "successfully"
> 
> Please also check in other locations, I might well have missed some ;-)

Of course, sorry for that)

> 
>> +	 * landlock restrictions.
>> +	 */
>> +	ASSERT_EQ(0, test_socket_variant(&self->prot_tested));
>> +
>> +	ruleset_fd =
>> +		landlock_create_ruleset(&ruleset_attr, sizeof(ruleset_attr), 0);
>> +	ASSERT_LE(0, ruleset_fd);
>> +
>> +	ASSERT_EQ(0, landlock_add_rule(ruleset_fd, LANDLOCK_RULE_SOCKET,
>> +				       &packet_socket_create, 0));
>> +	enforce_ruleset(_metadata, ruleset_fd);
>> +	ASSERT_EQ(0, close(ruleset_fd));
>> +
>> +	/*
>> +	 * (AF_INET, SOCK_PACKET) is an alias for the (AF_PACKET, SOCK_PACKET)
>> +	 * (Cf. __sock_create). Checks that Landlock does not restrict one pair
>> +	 * if the other was allowed.
>> +	 */
>> +	EXPECT_EQ(0, test_socket_variant(&self->prot_tested));
> 
> Why not check both AF_INET and AF_PACKET in both fixtures?
> Since they are synonymous, they should both work, no matter which
> of the two variants was used in the rule.
> 
> It would be slightly more comprehensive and make the fixture smaller.
> WDYT?

Agreed, prot_tested should be removed.

> 
>> +}
>> +
>>   TEST_HARNESS_MAIN
>> -- 
>> 2.34.1
>>
> 
> —Günther