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Message-ID: <2f67fa30-d4e6-3a1b-7166-eee33c734899@huawei-partners.com>
Date: Tue, 20 Aug 2024 15:32:06 +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 v2 3/9] selftests/landlock: Support
LANDLOCK_ACCESS_NET_LISTEN_TCP
8/20/2024 12:52 AM, Günther Noack wrote:
> On Wed, Aug 14, 2024 at 11:01:45AM +0800, Mikhail Ivanov wrote:
>> * Add listen_variant() to simplify listen(2) return code checking.
>> * Rename test_bind_and_connect() to test_restricted_net_fixture().
>> * Extend current net rules with LANDLOCK_ACCESS_NET_LISTEN_TCP access.
>> * Rename test port_specific.bind_connect_1023 to
>> port_specific.port_1023.
>> * Check little endian port restriction for listen in
>> ipv4_tcp.port_endianness.
>> * Some local renames and comment changes.
>>
>> Signed-off-by: Mikhail Ivanov <ivanov.mikhail1@...wei-partners.com>
>> ---
>> tools/testing/selftests/landlock/net_test.c | 198 +++++++++++---------
>> 1 file changed, 107 insertions(+), 91 deletions(-)
>>
>> diff --git a/tools/testing/selftests/landlock/net_test.c b/tools/testing/selftests/landlock/net_test.c
>> index f21cfbbc3638..8126f5c0160f 100644
>> --- a/tools/testing/selftests/landlock/net_test.c
>> +++ b/tools/testing/selftests/landlock/net_test.c
>> @@ -2,7 +2,7 @@
>> /*
>> * Landlock tests - Network
>> *
>> - * Copyright © 2022-2023 Huawei Tech. Co., Ltd.
>> + * Copyright © 2022-2024 Huawei Tech. Co., Ltd.
>> * Copyright © 2023 Microsoft Corporation
>> */
>>
>> @@ -22,6 +22,17 @@
>>
>> #include "common.h"
>>
>> +/* clang-format off */
>> +
>> +#define ACCESS_LAST LANDLOCK_ACCESS_NET_LISTEN_TCP
>> +
>> +#define ACCESS_ALL ( \
>> + LANDLOCK_ACCESS_NET_BIND_TCP | \
>> + LANDLOCK_ACCESS_NET_CONNECT_TCP | \
>> + LANDLOCK_ACCESS_NET_LISTEN_TCP)
>> +
>> +/* clang-format on */
>> +
>> const short sock_port_start = (1 << 10);
>>
>> static const char loopback_ipv4[] = "127.0.0.1";
>> @@ -282,6 +293,16 @@ static int connect_variant(const int sock_fd,
>> return connect_variant_addrlen(sock_fd, srv, get_addrlen(srv, false));
>> }
>>
>> +static int listen_variant(const int sock_fd, const int backlog)
>
> I believe socket_variant(), connect_variant() and bind_variant() were called
> like that because they got an instance of a service_fixture as an argument. The
> fixture instances are called variants. But we don't use these fixtures here.
>
> In fs_test.c, we also have some functions that behave much like system calls,
> but clean up after themselves and return errno, for easier use in assert. The
> naming scheme we have used there is "test_foo" (e.g. test_open()). I think this
> would be more appropriate here as a name?
I think such naming is suitable when a function represents a simple
separate test for specific operation that doesn't affect the behavior
of the caller. In current case we just need a wrapper under listen(2)
which returns -errno on failure. Pros of "listen_variant()" is that
it follows the style of other tested syscall helpers ("bind_variant()",
..) but it does seem to be semantically incorrect indeed.
I suggest using a listen(2) synonym - "do_listen()". WDYT?
>
>> +{
>> + int ret;
>> +
>> + ret = listen(sock_fd, backlog);
>> + if (ret < 0)
>> + return -errno;
>> + return ret;
>> +}
>> +
>> FIXTURE(protocol)
>> {
>> struct service_fixture srv0, srv1, srv2, unspec_any0, unspec_srv0;
>> @@ -438,9 +459,11 @@ FIXTURE_VARIANT_ADD(protocol, tcp_sandbox_with_unix_datagram) {
>> },
>> };
>>
>> -static void test_bind_and_connect(struct __test_metadata *const _metadata,
>> - const struct service_fixture *const srv,
>> - const bool deny_bind, const bool deny_connect)
>> +static void test_restricted_net_fixture(struct __test_metadata *const _metadata,
>> + const struct service_fixture *const srv,
>> + const bool deny_bind,
>> + const bool deny_connect,
>> + const bool deny_listen)
>> {
>> char buf = '\0';
>> int inval_fd, bind_fd, client_fd, status, ret;
>> @@ -512,8 +535,14 @@ static void test_bind_and_connect(struct __test_metadata *const _metadata,
>> EXPECT_EQ(0, ret);
>>
>> /* Creates a listening socket. */
>> - if (srv->protocol.type == SOCK_STREAM)
>> - EXPECT_EQ(0, listen(bind_fd, backlog));
>> + if (srv->protocol.type == SOCK_STREAM) {
>> + ret = listen_variant(bind_fd, backlog);
>> + if (deny_listen) {
>> + EXPECT_EQ(-EACCES, ret);
>> + } else {
>> + EXPECT_EQ(0, ret);
>> + }
>
> Hmm, passing the expected error code instead of a boolean to this function was not possible?
> Then you could just write
>
> EXPECT_EQ(expected_listen_error, listen_variant(bind_fd, backlog));
>
> ? (Apologies if this was discussed already.)
deny_* arguments are required not only to check an appropriate syscall
behavior. They also test and control the behavior of other operations in
the current helper (e.g. connect(2) returns -ECONNREFUSED on
"deny_bind | deny_listen", listen(2) is not called if deny_bind is set).
>
>> + }
>> }
>>
>> child = fork();
>> @@ -530,7 +559,7 @@ static void test_bind_and_connect(struct __test_metadata *const _metadata,
>> ret = connect_variant(connect_fd, srv);
>> if (deny_connect) {
>> EXPECT_EQ(-EACCES, ret);
>> - } else if (deny_bind) {
>> + } else if (deny_bind || deny_listen) {
>> /* No listening server. */
>> EXPECT_EQ(-ECONNREFUSED, ret);
>> } else {
>> @@ -545,7 +574,7 @@ static void test_bind_and_connect(struct __test_metadata *const _metadata,
>>
>> /* Accepts connection from the child. */
>> client_fd = bind_fd;
>> - if (!deny_bind && !deny_connect) {
>> + if (!deny_bind && !deny_connect && !deny_listen) {
>> if (srv->protocol.type == SOCK_STREAM) {
>> client_fd = accept(bind_fd, NULL, 0);
>> ASSERT_LE(0, client_fd);
>> @@ -571,16 +600,15 @@ TEST_F(protocol, bind)
>> {
>> if (variant->sandbox == TCP_SANDBOX) {
>> const struct landlock_ruleset_attr ruleset_attr = {
>> - .handled_access_net = LANDLOCK_ACCESS_NET_BIND_TCP |
>> - LANDLOCK_ACCESS_NET_CONNECT_TCP,
>> + .handled_access_net = ACCESS_ALL,
>> };
>> - const struct landlock_net_port_attr tcp_bind_connect_p0 = {
>> - .allowed_access = LANDLOCK_ACCESS_NET_BIND_TCP |
>> - LANDLOCK_ACCESS_NET_CONNECT_TCP,
>> + const struct landlock_net_port_attr tcp_not_restricted_p0 = {
>> + .allowed_access = ACCESS_ALL,
>> .port = self->srv0.port,
>> };
>> - const struct landlock_net_port_attr tcp_connect_p1 = {
>> - .allowed_access = LANDLOCK_ACCESS_NET_CONNECT_TCP,
>> + const struct landlock_net_port_attr tcp_denied_bind_p1 = {
>> + .allowed_access = ACCESS_ALL &
>> + ~LANDLOCK_ACCESS_NET_BIND_TCP,
>> .port = self->srv1.port,
>> };
>> int ruleset_fd;
>> @@ -589,48 +617,47 @@ TEST_F(protocol, bind)
>> sizeof(ruleset_attr), 0);
>> ASSERT_LE(0, ruleset_fd);
>>
>> - /* Allows connect and bind for the first port. */
>> + /* Allows all actions for the first port. */
>> ASSERT_EQ(0,
>> landlock_add_rule(ruleset_fd, LANDLOCK_RULE_NET_PORT,
>> - &tcp_bind_connect_p0, 0));
>> + &tcp_not_restricted_p0, 0));
>>
>> - /* Allows connect and denies bind for the second port. */
>> + /* Allows all actions despite bind. */
>> ASSERT_EQ(0,
>> landlock_add_rule(ruleset_fd, LANDLOCK_RULE_NET_PORT,
>> - &tcp_connect_p1, 0));
>> + &tcp_denied_bind_p1, 0));
>>
>> enforce_ruleset(_metadata, ruleset_fd);
>> EXPECT_EQ(0, close(ruleset_fd));
>> }
>> + bool restricted = is_restricted(&variant->prot, variant->sandbox);
>>
>> /* Binds a socket to the first port. */
>> - test_bind_and_connect(_metadata, &self->srv0, false, false);
>> + test_restricted_net_fixture(_metadata, &self->srv0, false, false,
>> + false);
>>
>> /* Binds a socket to the second port. */
>> - test_bind_and_connect(_metadata, &self->srv1,
>> - is_restricted(&variant->prot, variant->sandbox),
>> - false);
>> + test_restricted_net_fixture(_metadata, &self->srv1, restricted, false,
>> + false);
>>
>> /* Binds a socket to the third port. */
>> - test_bind_and_connect(_metadata, &self->srv2,
>> - is_restricted(&variant->prot, variant->sandbox),
>> - is_restricted(&variant->prot, variant->sandbox));
>> + test_restricted_net_fixture(_metadata, &self->srv2, restricted,
>> + restricted, restricted);
>> }
>>
>> TEST_F(protocol, connect)
>> {
>> if (variant->sandbox == TCP_SANDBOX) {
>> const struct landlock_ruleset_attr ruleset_attr = {
>> - .handled_access_net = LANDLOCK_ACCESS_NET_BIND_TCP |
>> - LANDLOCK_ACCESS_NET_CONNECT_TCP,
>> + .handled_access_net = ACCESS_ALL,
>> };
>> - const struct landlock_net_port_attr tcp_bind_connect_p0 = {
>> - .allowed_access = LANDLOCK_ACCESS_NET_BIND_TCP |
>> - LANDLOCK_ACCESS_NET_CONNECT_TCP,
>> + const struct landlock_net_port_attr tcp_not_restricted_p0 = {
>> + .allowed_access = ACCESS_ALL,
>> .port = self->srv0.port,
>> };
>> - const struct landlock_net_port_attr tcp_bind_p1 = {
>> - .allowed_access = LANDLOCK_ACCESS_NET_BIND_TCP,
>> + const struct landlock_net_port_attr tcp_denied_connect_p1 = {
>> + .allowed_access = ACCESS_ALL &
>> + ~LANDLOCK_ACCESS_NET_CONNECT_TCP,
>> .port = self->srv1.port,
>> };
>> int ruleset_fd;
>> @@ -639,28 +666,27 @@ TEST_F(protocol, connect)
>> sizeof(ruleset_attr), 0);
>> ASSERT_LE(0, ruleset_fd);
>>
>> - /* Allows connect and bind for the first port. */
>> + /* Allows all actions for the first port. */
>> ASSERT_EQ(0,
>> landlock_add_rule(ruleset_fd, LANDLOCK_RULE_NET_PORT,
>> - &tcp_bind_connect_p0, 0));
>> + &tcp_not_restricted_p0, 0));
>>
>> - /* Allows bind and denies connect for the second port. */
>> + /* Allows all actions despite connect. */
>> ASSERT_EQ(0,
>> landlock_add_rule(ruleset_fd, LANDLOCK_RULE_NET_PORT,
>> - &tcp_bind_p1, 0));
>> + &tcp_denied_connect_p1, 0));
>>
>> enforce_ruleset(_metadata, ruleset_fd);
>> EXPECT_EQ(0, close(ruleset_fd));
>> }
>> -
>> - test_bind_and_connect(_metadata, &self->srv0, false, false);
>> -
>> - test_bind_and_connect(_metadata, &self->srv1, false,
>> - is_restricted(&variant->prot, variant->sandbox));
>> -
>> - test_bind_and_connect(_metadata, &self->srv2,
>> - is_restricted(&variant->prot, variant->sandbox),
>> - is_restricted(&variant->prot, variant->sandbox));
>> + bool restricted = is_restricted(&variant->prot, variant->sandbox);
>> +
>> + test_restricted_net_fixture(_metadata, &self->srv0, false, false,
>> + false);
>> + test_restricted_net_fixture(_metadata, &self->srv1, false, restricted,
>> + false);
>> + test_restricted_net_fixture(_metadata, &self->srv2, restricted,
>> + restricted, restricted);
>> }
>>
>> TEST_F(protocol, bind_unspec)
>> @@ -761,7 +787,7 @@ TEST_F(protocol, connect_unspec)
>> ASSERT_LE(0, bind_fd);
>> EXPECT_EQ(0, bind_variant(bind_fd, &self->srv0));
>> if (self->srv0.protocol.type == SOCK_STREAM)
>> - EXPECT_EQ(0, listen(bind_fd, backlog));
>> + EXPECT_EQ(0, listen_variant(bind_fd, backlog));
>>
>> child = fork();
>> ASSERT_LE(0, child);
>> @@ -1127,8 +1153,8 @@ TEST_F(tcp_layers, ruleset_overlap)
>> * Forbids to connect to the socket because only one ruleset layer
>> * allows connect.
>> */
>> - test_bind_and_connect(_metadata, &self->srv0, false,
>> - variant->num_layers >= 2);
>> + test_restricted_net_fixture(_metadata, &self->srv0, false,
>> + variant->num_layers >= 2, false);
>> }
>>
>> TEST_F(tcp_layers, ruleset_expand)
>> @@ -1208,11 +1234,12 @@ TEST_F(tcp_layers, ruleset_expand)
>> EXPECT_EQ(0, close(ruleset_fd));
>> }
>>
>> - test_bind_and_connect(_metadata, &self->srv0, false,
>> - variant->num_layers >= 3);
>> + test_restricted_net_fixture(_metadata, &self->srv0, false,
>> + variant->num_layers >= 3, false);
>>
>> - test_bind_and_connect(_metadata, &self->srv1, variant->num_layers >= 1,
>> - variant->num_layers >= 2);
>> + test_restricted_net_fixture(_metadata, &self->srv1,
>> + variant->num_layers >= 1,
>> + variant->num_layers >= 2, false);
>> }
>>
>> /* clang-format off */
>> @@ -1230,16 +1257,6 @@ FIXTURE_TEARDOWN(mini)
>> {
>> }
>>
>> -/* clang-format off */
>> -
>> -#define ACCESS_LAST LANDLOCK_ACCESS_NET_CONNECT_TCP
>> -
>> -#define ACCESS_ALL ( \
>> - LANDLOCK_ACCESS_NET_BIND_TCP | \
>> - LANDLOCK_ACCESS_NET_CONNECT_TCP)
>> -
>> -/* clang-format on */
>> -
>> TEST_F(mini, network_access_rights)
>> {
>> const struct landlock_ruleset_attr ruleset_attr = {
>> @@ -1454,8 +1471,9 @@ TEST_F(mini, tcp_port_overflow)
>>
>> enforce_ruleset(_metadata, ruleset_fd);
>>
>> - test_bind_and_connect(_metadata, &srv_denied, true, true);
>> - test_bind_and_connect(_metadata, &srv_max_allowed, false, false);
>> + test_restricted_net_fixture(_metadata, &srv_denied, true, true, false);
>> + test_restricted_net_fixture(_metadata, &srv_max_allowed, false, false,
>> + false);
>> }
>>
>> FIXTURE(ipv4_tcp)
>> @@ -1485,22 +1503,21 @@ FIXTURE_TEARDOWN(ipv4_tcp)
>> TEST_F(ipv4_tcp, port_endianness)
>> {
>> const struct landlock_ruleset_attr ruleset_attr = {
>> - .handled_access_net = LANDLOCK_ACCESS_NET_BIND_TCP |
>> - LANDLOCK_ACCESS_NET_CONNECT_TCP,
>> + .handled_access_net = ACCESS_ALL,
>> };
>> const struct landlock_net_port_attr bind_host_endian_p0 = {
>> .allowed_access = LANDLOCK_ACCESS_NET_BIND_TCP,
>> /* Host port format. */
>> .port = self->srv0.port,
>> };
>> - const struct landlock_net_port_attr connect_big_endian_p0 = {
>> - .allowed_access = LANDLOCK_ACCESS_NET_CONNECT_TCP,
>> + const struct landlock_net_port_attr connect_listen_big_endian_p0 = {
>> + .allowed_access = LANDLOCK_ACCESS_NET_CONNECT_TCP |
>> + LANDLOCK_ACCESS_NET_LISTEN_TCP,
>> /* Big endian port format. */
>> .port = htons(self->srv0.port),
>> };
>> - const struct landlock_net_port_attr bind_connect_host_endian_p1 = {
>> - .allowed_access = LANDLOCK_ACCESS_NET_BIND_TCP |
>> - LANDLOCK_ACCESS_NET_CONNECT_TCP,
>> + const struct landlock_net_port_attr not_restricted_host_endian_p1 = {
>> + .allowed_access = ACCESS_ALL,
>> /* Host port format. */
>> .port = self->srv1.port,
>> };
>> @@ -1514,16 +1531,18 @@ TEST_F(ipv4_tcp, port_endianness)
>> ASSERT_EQ(0, landlock_add_rule(ruleset_fd, LANDLOCK_RULE_NET_PORT,
>> &bind_host_endian_p0, 0));
>> ASSERT_EQ(0, landlock_add_rule(ruleset_fd, LANDLOCK_RULE_NET_PORT,
>> - &connect_big_endian_p0, 0));
>> + &connect_listen_big_endian_p0, 0));
>> ASSERT_EQ(0, landlock_add_rule(ruleset_fd, LANDLOCK_RULE_NET_PORT,
>> - &bind_connect_host_endian_p1, 0));
>> + ¬_restricted_host_endian_p1, 0));
>> enforce_ruleset(_metadata, ruleset_fd);
>>
>> /* No restriction for big endinan CPU. */
>> - test_bind_and_connect(_metadata, &self->srv0, false, little_endian);
>> + test_restricted_net_fixture(_metadata, &self->srv0, false,
>> + little_endian, little_endian);
>>
>> /* No restriction for any CPU. */
>> - test_bind_and_connect(_metadata, &self->srv1, false, false);
>> + test_restricted_net_fixture(_metadata, &self->srv1, false, false,
>> + false);
>> }
>>
>> TEST_F(ipv4_tcp, with_fs)
>> @@ -1691,7 +1710,7 @@ TEST_F(port_specific, bind_connect_zero)
>> ret = bind_variant(bind_fd, &self->srv0);
>> EXPECT_EQ(0, ret);
>>
>> - EXPECT_EQ(0, listen(bind_fd, backlog));
>> + EXPECT_EQ(0, listen_variant(bind_fd, backlog));
>>
>> /* Connects on port 0. */
>> ret = connect_variant(connect_fd, &self->srv0);
>> @@ -1714,26 +1733,23 @@ TEST_F(port_specific, bind_connect_zero)
>> EXPECT_EQ(0, close(bind_fd));
>> }
>>
>> -TEST_F(port_specific, bind_connect_1023)
>> +TEST_F(port_specific, port_1023)
>> {
>> int bind_fd, connect_fd, ret;
>>
>> - /* Adds a rule layer with bind and connect actions. */
>> + /* Adds a rule layer with all actions. */
>> if (variant->sandbox == TCP_SANDBOX) {
>> const struct landlock_ruleset_attr ruleset_attr = {
>> - .handled_access_net = LANDLOCK_ACCESS_NET_BIND_TCP |
>> - LANDLOCK_ACCESS_NET_CONNECT_TCP
>> + .handled_access_net = ACCESS_ALL
>> };
>> /* A rule with port value less than 1024. */
>> - const struct landlock_net_port_attr tcp_bind_connect_low_range = {
>> - .allowed_access = LANDLOCK_ACCESS_NET_BIND_TCP |
>> - LANDLOCK_ACCESS_NET_CONNECT_TCP,
>> + const struct landlock_net_port_attr tcp_low_range_port = {
>> + .allowed_access = ACCESS_ALL,
>> .port = 1023,
>> };
>> /* A rule with 1024 port. */
>> - const struct landlock_net_port_attr tcp_bind_connect = {
>> - .allowed_access = LANDLOCK_ACCESS_NET_BIND_TCP |
>> - LANDLOCK_ACCESS_NET_CONNECT_TCP,
>> + const struct landlock_net_port_attr tcp_port_1024 = {
>> + .allowed_access = ACCESS_ALL,
>> .port = 1024,
>> };
>> int ruleset_fd;
>> @@ -1744,10 +1760,10 @@ TEST_F(port_specific, bind_connect_1023)
>>
>> ASSERT_EQ(0,
>> landlock_add_rule(ruleset_fd, LANDLOCK_RULE_NET_PORT,
>> - &tcp_bind_connect_low_range, 0));
>> + &tcp_low_range_port, 0));
>> ASSERT_EQ(0,
>> landlock_add_rule(ruleset_fd, LANDLOCK_RULE_NET_PORT,
>> - &tcp_bind_connect, 0));
>> + &tcp_port_1024, 0));
>>
>> enforce_ruleset(_metadata, ruleset_fd);
>> EXPECT_EQ(0, close(ruleset_fd));
>> @@ -1771,7 +1787,7 @@ TEST_F(port_specific, bind_connect_1023)
>> ret = bind_variant(bind_fd, &self->srv0);
>> clear_cap(_metadata, CAP_NET_BIND_SERVICE);
>> EXPECT_EQ(0, ret);
>> - EXPECT_EQ(0, listen(bind_fd, backlog));
>> + EXPECT_EQ(0, listen_variant(bind_fd, backlog));
>>
>> /* Connects on the binded port 1023. */
>> ret = connect_variant(connect_fd, &self->srv0);
>> @@ -1791,7 +1807,7 @@ TEST_F(port_specific, bind_connect_1023)
>> /* Binds on port 1024. */
>> ret = bind_variant(bind_fd, &self->srv0);
>> EXPECT_EQ(0, ret);
>> - EXPECT_EQ(0, listen(bind_fd, backlog));
>> + EXPECT_EQ(0, listen_variant(bind_fd, backlog));
>>
>> /* Connects on the binded port 1024. */
>> ret = connect_variant(connect_fd, &self->srv0);
>> --
>> 2.34.1
>>
>
> —Günther
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