Date:   Tue, 10 Jan 2023 18:40:56 +0100
From:   Mickaël Salaün <mic@...ikod.net>
To:     "Konstantin Meskhidze (A)" <konstantin.meskhidze@...wei.com>
Cc:     willemdebruijn.kernel@...il.com, gnoack3000@...il.com,
        linux-security-module@...r.kernel.org, netdev@...r.kernel.org,
        netfilter-devel@...r.kernel.org, artem.kuzin@...wei.com
Subject: Re: [PATCH v8 10/12] selftests/landlock: Add 10 new test suites
 dedicated to network


On 10/01/2023 06:03, Konstantin Meskhidze (A) wrote:
> 
> 
> 1/9/2023 3:46 PM, Mickaël Salaün пишет:
>>
>> On 21/10/2022 17:26, Konstantin Meskhidze wrote:
>>> These test suites try to check edge cases for TCP sockets
>>> bind() and connect() actions.
>>>
>>> socket:
>>> * bind_no_restrictions: Tests with non-landlocked ipv4 and ipv6 sockets.
>>> * bind_with_restrictions: Tests with mixed landlock rules for ipv4 and
>>> ipv6 sockets.
>>> * connect_no_restrictions: Tests with non-landlocked ipv4 and ipv6 sockets.
>>> * connect_with_restrictions: Tests with mixed landlock rules for ipv4 and
>>> ipv6 sockets.
>>> * connect_afunspec_no_restrictions: Tests with no landlock restrictions
>>> allowing to disconnect already connected socket with AF_UNSPEC socket
>>> family.
>>> * connect_afunspec_with_restrictions: Tests with landlocked process
>>> refusing to disconnect already connected socket.
>>> * ruleset_overlap: Tests with overlapping rules for one port.
>>> * ruleset_expanding: Tests with expanding rulesets in which rules are
>>> gradually added one by one, restricting sockets' connections.
>>> * inval: Tests with invalid user space supplied data:
>>>       - out of range ruleset attribute;
>>>       - unhandled allowed access;
>>>       - zero port value;
>>>       - zero access value;
>>>       - legitimate access values;
>>>
>>> layout1:
>>> * with_net: Tests with network bind() socket action within
>>> filesystem directory access test.
>>>
>>> Test coverage for security/landlock is 94.3% of 920 lines according
>>> to gcc/gcov-11.
>>>
>>> Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@...wei.com>
>>> ---
>>>
>>> Changes since v7:
>>> * Squashes all selftest commits.
>>> * Adds fs test with network bind() socket action.
>>> * Minor fixes.
>>>
>>> ---
>>>    security/landlock/ruleset.h                 |   2 -
>>>    tools/testing/selftests/landlock/config     |   4 +
>>>    tools/testing/selftests/landlock/fs_test.c  |  65 ++
>>>    tools/testing/selftests/landlock/net_test.c | 823 ++++++++++++++++++++
>>>    4 files changed, 892 insertions(+), 2 deletions(-)
>>>    create mode 100644 tools/testing/selftests/landlock/net_test.c
>>>
>>> diff --git a/security/landlock/ruleset.h b/security/landlock/ruleset.h
>>> index f272d2cd518c..ee1a02a404ce 100644
>>> --- a/security/landlock/ruleset.h
>>> +++ b/security/landlock/ruleset.h
>>> @@ -264,7 +264,6 @@ landlock_add_fs_access_mask(struct landlock_ruleset *const ruleset,
>>>
>>>    	/* Should already be checked in sys_landlock_create_ruleset(). */
>>>    	WARN_ON_ONCE(fs_access_mask != fs_mask);
>>> -	// TODO: Add tests to check "|=" and not "="
>>>    	ruleset->access_masks[layer_level] |=
>>>    		(fs_mask << LANDLOCK_SHIFT_ACCESS_FS);
>>>    }
>>> @@ -278,7 +277,6 @@ landlock_add_net_access_mask(struct landlock_ruleset *const ruleset,
>>>
>>>    	/* Should already be checked in sys_landlock_create_ruleset(). */
>>>    	WARN_ON_ONCE(net_access_mask != net_mask);
>>> -	// TODO: Add tests to check "|=" and not "="
>>>    	ruleset->access_masks[layer_level] |=
>>>    		(net_mask << LANDLOCK_SHIFT_ACCESS_NET);
>>>    }
>>> diff --git a/tools/testing/selftests/landlock/config b/tools/testing/selftests/landlock/config
>>> index 0f0a65287bac..71f7e9a8a64c 100644
>>> --- a/tools/testing/selftests/landlock/config
>>> +++ b/tools/testing/selftests/landlock/config
>>> @@ -1,3 +1,7 @@
>>> +CONFIG_INET=y
>>> +CONFIG_IPV6=y
>>> +CONFIG_NET=y
>>> +CONFIG_NET_NS=y
>>>    CONFIG_OVERLAY_FS=y
>>>    CONFIG_SECURITY_LANDLOCK=y
>>>    CONFIG_SECURITY_PATH=y
>>> diff --git a/tools/testing/selftests/landlock/fs_test.c b/tools/testing/selftests/landlock/fs_test.c
>>> index 20c1ac8485f1..5c52da1a5a69 100644
>>> --- a/tools/testing/selftests/landlock/fs_test.c
>>> +++ b/tools/testing/selftests/landlock/fs_test.c
>>> @@ -8,14 +8,17 @@
>>>     */
>>>
>>>    #define _GNU_SOURCE
>>> +#include <arpa/inet.h>
>>>    #include <fcntl.h>
>>>    #include <linux/landlock.h>
>>> +#include <netinet/in.h>
>>>    #include <sched.h>
>>>    #include <string.h>
>>>    #include <sys/capability.h>
>>>    #include <sys/mount.h>
>>>    #include <sys/prctl.h>
>>>    #include <sys/sendfile.h>
>>> +#include <sys/socket.h>
>>>    #include <sys/stat.h>
>>>    #include <sys/sysmacros.h>
>>>    #include <unistd.h>
>>> @@ -4366,4 +4369,66 @@ TEST_F_FORK(layout2_overlay, same_content_different_file)
>>>    	}
>>>    }
>>>
>>> +#define IP_ADDRESS "127.0.0.1"
>>> +
>>> +TEST_F_FORK(layout1, with_net)
>>> +{
>>> +	int sockfd;
>>> +	int sock_port = 15000;
>>> +	struct sockaddr_in addr4;
>>> +
>>> +	addr4.sin_family = AF_INET;
>>> +	addr4.sin_port = htons(sock_port);
>>> +	addr4.sin_addr.s_addr = inet_addr(IP_ADDRESS);
>>> +	memset(&addr4.sin_zero, '\0', 8);
>>> +
>>> +	const struct rule rules[] = {
>>> +		{
>>> +			.path = dir_s1d2,
>>> +			.access = ACCESS_RO,
>>> +		},
>>> +		{},
>>> +	};
>>> +
>>> +	struct landlock_ruleset_attr ruleset_attr_net = {
>>> +		.handled_access_net = LANDLOCK_ACCESS_NET_BIND_TCP |
>>> +				      LANDLOCK_ACCESS_NET_CONNECT_TCP,
>>> +	};
>>> +	struct landlock_net_service_attr net_service = {
>>> +		.allowed_access = LANDLOCK_ACCESS_NET_BIND_TCP,
>>> +
>>> +		.port = sock_port,
>>> +	};
>>> +
>>> +	/* Creates ruleset for network access. */
>>> +	const int ruleset_fd_net = landlock_create_ruleset(
>>> +		&ruleset_attr_net, sizeof(ruleset_attr_net), 0);
>>> +	ASSERT_LE(0, ruleset_fd_net);
>>> +
>>> +	/* Adds a network rule. */
>>> +	ASSERT_EQ(0,
>>> +		  landlock_add_rule(ruleset_fd_net, LANDLOCK_RULE_NET_SERVICE,
>>> +				    &net_service, 0));
>>> +
>>> +	enforce_ruleset(_metadata, ruleset_fd_net);
>>> +	ASSERT_EQ(0, close(ruleset_fd_net));
>>> +
>>> +	const int ruleset_fd = create_ruleset(_metadata, ACCESS_RW, rules);
>>> +	ASSERT_LE(0, ruleset_fd);
>>> +	enforce_ruleset(_metadata, ruleset_fd);
>>> +	ASSERT_EQ(0, close(ruleset_fd));
>>> +
>>> +	/* Tests on a directory with the network rule loaded. */
>>> +	ASSERT_EQ(0, test_open(dir_s1d2, O_RDONLY));
>>> +	ASSERT_EQ(0, test_open(file1_s1d2, O_RDONLY));
>>> +
>>> +	sockfd = socket(AF_INET, SOCK_STREAM | SOCK_CLOEXEC, 0);
>>> +	ASSERT_LE(0, sockfd);
>>> +	/* Binds a socket to port 15000. */
>>> +	ASSERT_EQ(0, bind(sockfd, &addr4, sizeof(addr4)));
>>> +
>>> +	/* Closes bounded socket. */
>>> +	ASSERT_EQ(0, close(sockfd));
>>> +}
>>> +
>>>    TEST_HARNESS_MAIN
>>> diff --git a/tools/testing/selftests/landlock/net_test.c b/tools/testing/selftests/landlock/net_test.c
>>> new file mode 100644
>>> index 000000000000..d1548bd7ab60
>>> --- /dev/null
>>> +++ b/tools/testing/selftests/landlock/net_test.c
>>> @@ -0,0 +1,823 @@
>>> +// SPDX-License-Identifier: GPL-2.0-only
>>> +/*
>>> + * Landlock tests - Network
>>> + *
>>> + * Copyright (C) 2022 Huawei Tech. Co., Ltd.
>>> + */
>>> +
>>> +#define _GNU_SOURCE
>>> +#include <arpa/inet.h>
>>> +#include <errno.h>
>>> +#include <fcntl.h>
>>> +#include <linux/landlock.h>
>>> +#include <netinet/in.h>
>>> +#include <sched.h>
>>> +#include <string.h>
>>> +#include <sys/prctl.h>
>>> +#include <sys/socket.h>
>>> +#include <sys/types.h>
>>> +
>>> +#include "common.h"
>>> +
>>> +#define MAX_SOCKET_NUM 10
>>> +
>>> +#define SOCK_PORT_START 3470
>>> +#define SOCK_PORT_ADD 10
>>> +
>>> +#define IP_ADDRESS "127.0.0.1"
>>> +
>>> +/* Number pending connections queue to be hold. */
>>> +#define BACKLOG 10
>>> +
>>> +const struct sockaddr addr_unspec = { .sa_family = AF_UNSPEC };
>>> +
>>> +/* Invalid attribute, out of landlock network access range. */
>>> +#define LANDLOCK_INVAL_ATTR 7
>>> +
>>> +FIXTURE(socket)
>>> +{
>>> +	uint port[MAX_SOCKET_NUM];
>>> +	struct sockaddr_in addr4[MAX_SOCKET_NUM];
>>> +	struct sockaddr_in6 addr6[MAX_SOCKET_NUM];
>>> +};
>>> +
>>> +/* struct _fixture_variant_socket */
>>> +FIXTURE_VARIANT(socket)
>>> +{
>>> +	const bool is_ipv4;
>>> +};
>>> +
>>> +/* clang-format off */
>>> +FIXTURE_VARIANT_ADD(socket, ipv4) {
>>> +	/* clang-format on */
>>> +	.is_ipv4 = true,
>>> +};
>>> +
>>> +/* clang-format off */
>>> +FIXTURE_VARIANT_ADD(socket, ipv6) {
>>> +	/* clang-format on */
>>> +	.is_ipv4 = false,
>>> +};
>>> +
>>> +static int
>>> +create_socket_variant(const struct _fixture_variant_socket *const variant,
>>> +		      const int type)
>>> +{
>>> +	if (variant->is_ipv4)
>>> +		return socket(AF_INET, type | SOCK_CLOEXEC, 0);
>>> +	else
>>> +		return socket(AF_INET6, type | SOCK_CLOEXEC, 0);
>>> +}
>>> +
>>> +static int bind_variant(const struct _fixture_variant_socket *const variant,
>>> +			const int sockfd,
>>> +			const struct _test_data_socket *const self,
>>> +			const size_t index)
>>> +{
>>> +	if (variant->is_ipv4)
>>> +		return bind(sockfd, &self->addr4[index],
>>> +			    sizeof(self->addr4[index]));
>>> +	else
>>> +		return bind(sockfd, &self->addr6[index],
>>> +			    sizeof(self->addr6[index]));
>>> +}
>>> +
>>> +static int connect_variant(const struct _fixture_variant_socket *const variant,
>>> +			   const int sockfd,
>>> +			   const struct _test_data_socket *const self,
>>> +			   const size_t index)
>>> +{
>>> +	if (variant->is_ipv4)
>>> +		return connect(sockfd, &self->addr4[index],
>>> +			       sizeof(self->addr4[index]));
>>> +	else
>>> +		return connect(sockfd, &self->addr6[index],
>>> +			       sizeof(self->addr6[index]));
>>> +}
>>> +
>>> +FIXTURE_SETUP(socket)
>>> +{
>>> +	int i;
>>> +
>>> +	/* Creates IPv4 socket addresses. */
>>> +	for (i = 0; i < MAX_SOCKET_NUM; i++) {
>>> +		self->port[i] = SOCK_PORT_START + SOCK_PORT_ADD * i;
>>> +		self->addr4[i].sin_family = AF_INET;
>>> +		self->addr4[i].sin_port = htons(self->port[i]);
>>> +		self->addr4[i].sin_addr.s_addr = inet_addr(IP_ADDRESS);
>>> +		memset(&(self->addr4[i].sin_zero), '\0', 8);
>>> +	}
>>> +
>>> +	/* Creates IPv6 socket addresses. */
>>> +	for (i = 0; i < MAX_SOCKET_NUM; i++) {
>>> +		self->port[i] = SOCK_PORT_START + SOCK_PORT_ADD * i;
>>> +		self->addr6[i].sin6_family = AF_INET6;
>>> +		self->addr6[i].sin6_port = htons(self->port[i]);
>>> +		inet_pton(AF_INET6, IP_ADDRESS, &(self->addr6[i].sin6_addr));
>>> +	}
>>> +
>>> +	set_cap(_metadata, CAP_SYS_ADMIN);
>>> +	ASSERT_EQ(0, unshare(CLONE_NEWNET));
>>> +	ASSERT_EQ(0, system("ip link set dev lo up"));
>>> +	clear_cap(_metadata, CAP_SYS_ADMIN);
>>> +}
>>> +
>>> +FIXTURE_TEARDOWN(socket)
>>> +{
>>> +}
>>> +
>>> +TEST_F_FORK(socket, bind_no_restrictions)
>>> +{
>>> +	int sockfd;
>>> +
>>> +	sockfd = create_socket_variant(variant, SOCK_STREAM);
>>> +	ASSERT_LE(0, sockfd);
>>> +
>>> +	/* Binds a socket to port[0]. */
>>> +	ASSERT_EQ(0, bind_variant(variant, sockfd, self, 0));
>>> +
>>> +	ASSERT_EQ(0, close(sockfd));
>>> +}
>>> +
>>> +TEST_F_FORK(socket, bind_with_restrictions)
>>> +{
>>> +	int sockfd;
>>> +
>>> +	struct landlock_ruleset_attr ruleset_attr = {
>>> +		.handled_access_net = LANDLOCK_ACCESS_NET_BIND_TCP |
>>> +				      LANDLOCK_ACCESS_NET_CONNECT_TCP,
>>> +	};
>>> +	struct landlock_net_service_attr net_service_1 = {
>>> +		.allowed_access = LANDLOCK_ACCESS_NET_BIND_TCP |
>>> +				  LANDLOCK_ACCESS_NET_CONNECT_TCP,
>>> +		.port = self->port[0],
>>> +	};
>>> +	struct landlock_net_service_attr net_service_2 = {
>>> +		.allowed_access = LANDLOCK_ACCESS_NET_CONNECT_TCP,
>>> +		.port = self->port[1],
>>> +	};
>>> +	struct landlock_net_service_attr net_service_3 = {
>>> +		.allowed_access = 0,
>>> +		.port = self->port[2],
>>> +	};
>>> +
>>> +	const int ruleset_fd =
>>> +		landlock_create_ruleset(&ruleset_attr, sizeof(ruleset_attr), 0);
>>> +	ASSERT_LE(0, ruleset_fd);
>>> +
>>> +	/* Allows connect and bind operations to the port[0] socket. */
>>> +	ASSERT_EQ(0, landlock_add_rule(ruleset_fd, LANDLOCK_RULE_NET_SERVICE,
>>> +				       &net_service_1, 0));
>>> +	/* Allows connect and deny bind operations to the port[1] socket. */
>>> +	ASSERT_EQ(0, landlock_add_rule(ruleset_fd, LANDLOCK_RULE_NET_SERVICE,
>>> +				       &net_service_2, 0));
>>> +	/*
>>> +	 * Empty allowed_access (i.e. deny rules) are ignored in network actions
>>> +	 * for port[2] socket.
>>> +	 */
>>> +	ASSERT_EQ(-1, landlock_add_rule(ruleset_fd, LANDLOCK_RULE_NET_SERVICE,
>>> +					&net_service_3, 0));
>>> +	ASSERT_EQ(ENOMSG, errno);
>>> +
>>> +	/* Enforces the ruleset. */
>>> +	enforce_ruleset(_metadata, ruleset_fd);
>>> +
>>> +	sockfd = create_socket_variant(variant, SOCK_STREAM);
>>> +	ASSERT_LE(0, sockfd);
>>> +	/* Binds a socket to port[0]. */
>>> +	ASSERT_EQ(0, bind_variant(variant, sockfd, self, 0));
>>> +
>>> +	/* Closes bounded socket. */
>>> +	ASSERT_EQ(0, close(sockfd));
>>> +
>>> +	sockfd = create_socket_variant(variant, SOCK_STREAM);
>>> +	ASSERT_LE(0, sockfd);
>>> +	/* Binds a socket to port[1]. */
>>> +	ASSERT_EQ(-1, bind_variant(variant, sockfd, self, 1));
>>> +	ASSERT_EQ(EACCES, errno);
>>> +
>>> +	sockfd = create_socket_variant(variant, SOCK_STREAM);
>>> +	ASSERT_LE(0, sockfd);
>>> +	/* Binds a socket to port[2]. */
>>> +	ASSERT_EQ(-1, bind_variant(variant, sockfd, self, 2));
>>> +	ASSERT_EQ(EACCES, errno);
>>
>> This is inconsistent with the bind_no_restrictions test. If you
>> deduplicate the tests with and without restrictions (i.e. only one
>> "bind" test, and another "connect"…), you can extend
>> FIXTURE_VARIANT(socket) with a new const bool enforce_landlock, and
>> check that in all tests to either do Landlock syscalls or not. You can
>> still initialize most variable whatever Landlock should be enforced or
>> not (e.g. ruleset_attr, net_service_1…) to make it easiear to read.
>>
> 
>     I think it's not a deduplication. Tests enforeced with landlock are
> more various regarding port and net_service attributes used. The number
> of landlock atributes vary from test ot test. I'dont see how to unify it
> with FIXTURE_VARIANT and enforce_landlock const will it make harder
> merging tests.
> Please your opinion and suggestions?

What about that?

TEST_F_FORK(socket, bind)
{
	int sockfd;

	struct landlock_ruleset_attr ruleset_attr = {
		.handled_access_net = LANDLOCK_ACCESS_NET_BIND_TCP |
				      LANDLOCK_ACCESS_NET_CONNECT_TCP,
	};
	struct landlock_net_service_attr net_service_1 = {
		.allowed_access = LANDLOCK_ACCESS_NET_BIND_TCP |
				  LANDLOCK_ACCESS_NET_CONNECT_TCP,
		.port = self->port[0],
	};
	struct landlock_net_service_attr net_service_2 = {
		.allowed_access = LANDLOCK_ACCESS_NET_CONNECT_TCP,
		.port = self->port[1],
	};
	struct landlock_net_service_attr net_service_3 = {
		.allowed_access = 0,
		.port = self->port[2],
	};
	int ruleset_fd, ret;

	if (variant->is_sandboxed) {
		ruleset_fd = landlock_create_ruleset(&ruleset_attr,
						     sizeof(ruleset_attr), 0);
		ASSERT_LE(0, ruleset_fd);

		/* Allows connect and bind operations to the port[0] socket. */
		ASSERT_EQ(0, landlock_add_rule(ruleset_fd,
					       LANDLOCK_RULE_NET_SERVICE,
					       &net_service_1, 0));

		/* Allows connect and deny bind operations to the port[1] socket. */
		ASSERT_EQ(0, landlock_add_rule(ruleset_fd,
					       LANDLOCK_RULE_NET_SERVICE,
					       &net_service_2, 0));

		/*
		 * Empty allowed_access (i.e. deny rules) are ignored in network actions
		 * for port[2] socket.
		 */
		ASSERT_EQ(-1, landlock_add_rule(ruleset_fd,
						LANDLOCK_RULE_NET_SERVICE,
						&net_service_3, 0));
		ASSERT_EQ(ENOMSG, errno);

		enforce_ruleset(_metadata, ruleset_fd);
		ASSERT_EQ(0, close(ruleset_fd));
	}

	sockfd = create_socket_variant(variant, SOCK_STREAM);
	ASSERT_LE(0, sockfd);
	/* Binds a socket to port[0]. */
	ASSERT_EQ(0, bind_variant(variant, sockfd, self, 0));

	/* Closes bounded socket. */
	ASSERT_EQ(0, close(sockfd));

	sockfd = create_socket_variant(variant, SOCK_STREAM);
	ASSERT_LE(0, sockfd);
	/* Binds a socket to port[1]. */
	ret = bind_variant(variant, sockfd, self, 1);
	if (variant->is_sandboxed) {
		ASSERT_EQ(-1, ret);
		ASSERT_EQ(EACCES, errno);
	} else {
		ASSERT_EQ(0, ret);
	}

	sockfd = create_socket_variant(variant, SOCK_STREAM);
	ASSERT_LE(0, sockfd);
	/* Binds a socket to port[2]. */
	ret = bind_variant(variant, sockfd, self, 2);
	if (variant->is_sandboxed) {
		ASSERT_EQ(-1, ret);
		ASSERT_EQ(EACCES, errno);
	} else {
		ASSERT_EQ(0, ret);
	}
}

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