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Message-ID: <20240816.His9oihaigei@digikod.net>
Date: Fri, 16 Aug 2024 23:23:05 +0200
From: Mickaël Salaün <mic@...ikod.net>
To: Tahera Fahimi <fahimitahera@...il.com>
Cc: outreachy@...ts.linux.dev, gnoack@...gle.com, paul@...l-moore.com,
jmorris@...ei.org, serge@...lyn.com, linux-security-module@...r.kernel.org,
linux-kernel@...r.kernel.org, bjorn3_gh@...tonmail.com, jannh@...gle.com,
netdev@...r.kernel.org
Subject: Re: [PATCH v9 2/5] selftests/Landlock: Abstract unix socket
restriction tests
Please make sure all subject's prefixes have "landlock", not "Landlock"
for consistency with current commits.
On Wed, Aug 14, 2024 at 12:22:20AM -0600, Tahera Fahimi wrote:
> The patch introduces Landlock ABI version 6 and has three types of tests
> that examines different scenarios for abstract unix socket connection:
> 1) unix_socket: base tests of the abstract socket scoping mechanism for a
> landlocked process, same as the ptrace test.
> 2) optional_scoping: generates three processes with different domains and
> tests if a process with a non-scoped domain can connect to other
> processes.
> 3) unix_sock_special_cases: since the socket's creator credentials are used
> for scoping sockets, this test examines the cases where the socket's
> credentials are different from the process using it.
>
> Signed-off-by: Tahera Fahimi <fahimitahera@...il.com>
> ---
> Changes in versions:
> v9:
> - Move pathname_address_sockets to a different patch.
> - Extend optional_scoping test scenarios.
> - Removing hardcoded numbers and using "backlog" instead.
You may have missed some parts of my previous review (e.g. local
variables).
> V8:
> - Move tests to scoped_abstract_unix_test.c file.
> - To avoid potential conflicts among Unix socket names in different tests,
> set_unix_address is added to common.h to set different sun_path for Unix sockets.
> - protocol_variant and service_fixture structures are also moved to common.h
> - Adding pathname_address_sockets to cover all types of address formats
> for unix sockets, and moving remove_path() to common.h to reuse in this test.
> V7:
> - Introducing landlock ABI version 6.
> - Adding some edge test cases to optional_scoping test.
> - Using `enum` for different domains in optional_scoping tests.
> - Extend unix_sock_special_cases test cases for connected(SOCK_STREAM) sockets.
> - Modifying inline comments.
> V6:
> - Introducing optional_scoping test which ensures a sandboxed process with a
> non-scoped domain can still connect to another abstract unix socket(either
> sandboxed or non-sandboxed).
> - Introducing unix_sock_special_cases test which tests examines scenarios where
> the connecting sockets have different domain than the process using them.
> V4:
> - Introducing unix_socket to evaluate the basic scoping mechanism for abstract
> unix sockets.
> ---
> tools/testing/selftests/landlock/base_test.c | 2 +-
> tools/testing/selftests/landlock/common.h | 38 +
> tools/testing/selftests/landlock/net_test.c | 31 +-
> .../landlock/scoped_abstract_unix_test.c | 942 ++++++++++++++++++
> 4 files changed, 982 insertions(+), 31 deletions(-)
> create mode 100644 tools/testing/selftests/landlock/scoped_abstract_unix_test.c
>
> +static void create_unix_domain(struct __test_metadata *const _metadata)
> +{
> + int ruleset_fd;
> + const struct landlock_ruleset_attr ruleset_attr = {
> + .scoped = LANDLOCK_SCOPED_ABSTRACT_UNIX_SOCKET,
> + };
> +
> + ruleset_fd =
> + landlock_create_ruleset(&ruleset_attr, sizeof(ruleset_attr), 0);
> + EXPECT_LE(0, ruleset_fd)
> + {
> + TH_LOG("Failed to create a ruleset: %s", strerror(errno));
> + }
> + enforce_ruleset(_metadata, ruleset_fd);
> + EXPECT_EQ(0, close(ruleset_fd));
> +}
> +
> +/* clang-format off */
It should not be required to add this clang-format comment here nor in
most places, except variant declarations (that might change if we remove
variables though).
> +FIXTURE(unix_socket)
> +{
> + struct service_fixture stream_address, dgram_address;
> + int server, client, dgram_server, dgram_client;
These variables don't need to be in the fixture but they should be local
instead (and scoped to the if/else condition where they are used).
> +};
> +
> +/* clang-format on */
> +FIXTURE_VARIANT(unix_socket)
> +{
> + bool domain_both;
> + bool domain_parent;
> + bool domain_child;
> + bool connect_to_parent;
> +};
> +/*
> + * Test UNIX_STREAM_CONNECT and UNIX_MAY_SEND for parent and child,
> + * when they have scoped domain or no domain.
> + */
> +TEST_F(unix_socket, abstract_unix_socket)
> +{
> + int status;
> + pid_t child;
> + bool can_connect_to_parent, can_connect_to_child;
> + int err, err_dgram;
> + int pipe_child[2], pipe_parent[2];
> + char buf_parent;
> +
> + /*
> + * can_connect_to_child is true if a parent process can connect to its
> + * child process. The parent process is not isolated from the child
> + * with a dedicated Landlock domain.
> + */
> + can_connect_to_child = !variant->domain_parent;
> + /*
> + * can_connect_to_parent is true if a child process can connect to its
> + * parent process. This depends on the child process is not isolated from
> + * the parent with a dedicated Landlock domain.
> + */
> + can_connect_to_parent = !variant->domain_child;
> +
> + ASSERT_EQ(0, pipe2(pipe_child, O_CLOEXEC));
> + ASSERT_EQ(0, pipe2(pipe_parent, O_CLOEXEC));
> + if (variant->domain_both) {
> + create_unix_domain(_metadata);
> + if (!__test_passed(_metadata))
> + return;
> + }
> +
> + child = fork();
> + ASSERT_LE(0, child);
> + if (child == 0) {
> + char buf_child;
> +
> + ASSERT_EQ(0, close(pipe_parent[1]));
> + ASSERT_EQ(0, close(pipe_child[0]));
> + if (variant->domain_child)
> + create_unix_domain(_metadata);
> +
> + /* Waits for the parent to be in a domain, if any. */
> + ASSERT_EQ(1, read(pipe_parent[0], &buf_child, 1));
> +
> + if (variant->connect_to_parent) {
> + self->client = socket(AF_UNIX, SOCK_STREAM, 0);
int stream_client;
stream_client = socket(AF_UNIX, SOCK_STREAM, 0);
ditto for dgram_client
> + self->dgram_client = socket(AF_UNIX, SOCK_DGRAM, 0);
> +
> + ASSERT_NE(-1, self->client);
> + ASSERT_NE(-1, self->dgram_client);
> + ASSERT_EQ(1, read(pipe_parent[0], &buf_child, 1));
> +
> + err = connect(self->client,
> + &self->stream_address.unix_addr,
> + (self->stream_address).unix_addr_len);
> + err_dgram =
> + connect(self->dgram_client,
> + &self->dgram_address.unix_addr,
> + (self->dgram_address).unix_addr_len);
> +
> + if (can_connect_to_parent) {
> + EXPECT_EQ(0, err);
> + EXPECT_EQ(0, err_dgram);
> + } else {
> + EXPECT_EQ(-1, err);
> + EXPECT_EQ(-1, err_dgram);
> + EXPECT_EQ(EPERM, errno);
> + }
EXPECT_EQ(0, close(stream_client));
EXPECT_EQ(0, close(dgram_client));
> + } else {
> + self->server = socket(AF_UNIX, SOCK_STREAM, 0);
int stream_server;
server = socket(AF_UNIX, SOCK_STREAM, 0);
ditto for dgram_server
> + self->dgram_server = socket(AF_UNIX, SOCK_DGRAM, 0);
> + ASSERT_NE(-1, self->server);
> + ASSERT_NE(-1, self->dgram_server);
> +
> + ASSERT_EQ(0,
> + bind(self->server,
> + &self->stream_address.unix_addr,
> + (self->stream_address).unix_addr_len));
> + ASSERT_EQ(0, bind(self->dgram_server,
> + &self->dgram_address.unix_addr,
> + (self->dgram_address).unix_addr_len));
> + ASSERT_EQ(0, listen(self->server, backlog));
> +
> + /* signal to parent that child is listening */
> + ASSERT_EQ(1, write(pipe_child[1], ".", 1));
> + /* wait to connect */
> + ASSERT_EQ(1, read(pipe_parent[0], &buf_child, 1));
ditto
> + }
> + _exit(_metadata->exit_code);
> + return;
> + }
> +
> + ASSERT_EQ(0, close(pipe_child[1]));
> + ASSERT_EQ(0, close(pipe_parent[0]));
> +
> + if (variant->domain_parent)
> + create_unix_domain(_metadata);
> +
> + /* Signals that the parent is in a domain, if any. */
> + ASSERT_EQ(1, write(pipe_parent[1], ".", 1));
> +
> + if (!variant->connect_to_parent) {
> + self->client = socket(AF_UNIX, SOCK_STREAM, 0);
> + self->dgram_client = socket(AF_UNIX, SOCK_DGRAM, 0);
ditto
> +
> + ASSERT_NE(-1, self->client);
> + ASSERT_NE(-1, self->dgram_client);
> +
> + /* Waits for the child to listen */
> + ASSERT_EQ(1, read(pipe_child[0], &buf_parent, 1));
> + err = connect(self->client, &self->stream_address.unix_addr,
> + (self->stream_address).unix_addr_len);
> + err_dgram = connect(self->dgram_client,
> + &self->dgram_address.unix_addr,
> + (self->dgram_address).unix_addr_len);
> +
> + if (can_connect_to_child) {
> + EXPECT_EQ(0, err);
> + EXPECT_EQ(0, err_dgram);
> + } else {
> + EXPECT_EQ(-1, err);
> + EXPECT_EQ(-1, err_dgram);
> + EXPECT_EQ(EPERM, errno);
> + }
> + ASSERT_EQ(1, write(pipe_parent[1], ".", 1));
ditto
> + } else {
> + self->server = socket(AF_UNIX, SOCK_STREAM, 0);
> + self->dgram_server = socket(AF_UNIX, SOCK_DGRAM, 0);
ditto
> + ASSERT_NE(-1, self->server);
> + ASSERT_NE(-1, self->dgram_server);
> + ASSERT_EQ(0, bind(self->server, &self->stream_address.unix_addr,
> + (self->stream_address).unix_addr_len));
> + ASSERT_EQ(0, bind(self->dgram_server,
> + &self->dgram_address.unix_addr,
> + (self->dgram_address).unix_addr_len));
> + ASSERT_EQ(0, listen(self->server, backlog));
> +
> + /* signal to child that parent is listening */
> + ASSERT_EQ(1, write(pipe_parent[1], ".", 1));
ditto
> + }
> +
> + ASSERT_EQ(child, waitpid(child, &status, 0));
> +
> + if (WIFSIGNALED(status) || !WIFEXITED(status) ||
> + WEXITSTATUS(status) != EXIT_SUCCESS)
> + _metadata->exit_code = KSFT_FAIL;
> +}
> +
> +/*
> + * ###################
> + * # ####### # P3 -> P2 : allow
> + * # P1----# P2 # # P3 -> P1 : deny
> + * # # | # #
> + * # # P3 # #
> + * # ####### #
> + * ###################
> + */
> +/* clang-format off */
> +FIXTURE_VARIANT_ADD(optional_scoping, all_scoped) {
> + .domain_all = SCOPE_SANDBOX,
> + .domain_parent = NO_SANDBOX,
> + .domain_children = SCOPE_SANDBOX,
> + .domain_child = NO_SANDBOX,
> + .domain_grand_child = NO_SANDBOX,
> + .type = SOCK_DGRAM,
There are spaces instead of tabs here.
> + /* clang-format on */
> +};
> +/*
> + * ###### P3 -> P2 : deny
> + * # P1 #----P2 P3 -> P1 : deny
> + * ###### |
> + * |
> + * ######
> + * # P3 #
> + * ######
> + */
> +/* clang-format off */
> +FIXTURE_VARIANT_ADD(optional_scoping, deny_with_self_and_parents_domain) {
> + .domain_all = NO_SANDBOX,
> + .domain_parent = SCOPE_SANDBOX,
> + .domain_children = NO_SANDBOX,
> + .domain_child = NO_SANDBOX,
> + .domain_grand_child = SCOPE_SANDBOX,
> + .type = SOCK_STREAM,
ditto
> + /* clang-format on */
> +};
> +
> +/*
Extra space
> + * Test UNIX_STREAM_CONNECT and UNIX_MAY_SEND for parent, child
> + * and grand child processes when they can have scoped or non-scoped
> + * domains.
> + **/
Extra '*'
> +TEST_F(optional_scoping, unix_scoping)
> +{
> + pid_t child;
> + int status;
> + bool can_connect_to_parent, can_connect_to_child;
> + int pipe_parent[2];
> +
> + can_connect_to_child =
> + (variant->domain_grand_child == SCOPE_SANDBOX) ? false : true;
No need for `? false : true`, just use comparison result:
can_connect_to_child = (variant->domain_grand_child != SCOPE_SANDBOX);
> +
> + can_connect_to_parent = (!can_connect_to_child ||
> + variant->domain_children == SCOPE_SANDBOX) ?
> + false :
> + true;
ditto
> +
> + ASSERT_EQ(0, pipe2(pipe_parent, O_CLOEXEC));
> +
> + if (variant->domain_all == OTHER_SANDBOX)
> + create_fs_domain(_metadata);
> + else if (variant->domain_all == SCOPE_SANDBOX)
> + create_unix_domain(_metadata);
> +
> + child = fork();
> + ASSERT_LE(0, child);
> + if (child == 0) {
> + int pipe_child[2];
> +
> + ASSERT_EQ(0, pipe2(pipe_child, O_CLOEXEC));
> + pid_t grand_child;
> +
> + if (variant->domain_children == OTHER_SANDBOX)
> + create_fs_domain(_metadata);
> + else if (variant->domain_children == SCOPE_SANDBOX)
> + create_unix_domain(_metadata);
> +
> + grand_child = fork();
> + ASSERT_LE(0, grand_child);
> + if (grand_child == 0) {
> + ASSERT_EQ(0, close(pipe_parent[1]));
> + ASSERT_EQ(0, close(pipe_child[1]));
> +
> + char buf1, buf2;
> + int err;
> +
> + if (variant->domain_grand_child == OTHER_SANDBOX)
> + create_fs_domain(_metadata);
> + else if (variant->domain_grand_child == SCOPE_SANDBOX)
> + create_unix_domain(_metadata);
> +
> + self->client = socket(AF_UNIX, variant->type, 0);
ditto
> + ASSERT_NE(-1, self->client);
> +
> + ASSERT_EQ(1, read(pipe_child[0], &buf2, 1));
> + err = connect(self->client,
> + &self->child_address.unix_addr,
> + (self->child_address).unix_addr_len);
> + if (can_connect_to_child) {
> + EXPECT_EQ(0, err);
> + } else {
> + EXPECT_EQ(-1, err);
> + EXPECT_EQ(EPERM, errno);
> + }
> +
> + if (variant->type == SOCK_STREAM) {
> + EXPECT_EQ(0, close(self->client));
> + self->client =
> + socket(AF_UNIX, variant->type, 0);
> + ASSERT_NE(-1, self->client);
> + }
> +
> + ASSERT_EQ(1, read(pipe_parent[0], &buf1, 1));
> + err = connect(self->client,
> + &self->parent_address.unix_addr,
> + (self->parent_address).unix_addr_len);
> + if (can_connect_to_parent) {
> + EXPECT_EQ(0, err);
> + } else {
> + EXPECT_EQ(-1, err);
> + EXPECT_EQ(EPERM, errno);
> + }
> + EXPECT_EQ(0, close(self->client));
> +
> + _exit(_metadata->exit_code);
> + return;
> + }
> +
> + ASSERT_EQ(0, close(pipe_child[0]));
> + if (variant->domain_child == OTHER_SANDBOX)
> + create_fs_domain(_metadata);
> + else if (variant->domain_child == SCOPE_SANDBOX)
> + create_unix_domain(_metadata);
> +
> + self->child_server = socket(AF_UNIX, variant->type, 0);
> + ASSERT_NE(-1, self->child_server);
> + ASSERT_EQ(0, bind(self->child_server,
> + &self->child_address.unix_addr,
> + (self->child_address).unix_addr_len));
> + if (variant->type == SOCK_STREAM)
> + ASSERT_EQ(0, listen(self->child_server, backlog));
> +
> + ASSERT_EQ(1, write(pipe_child[1], ".", 1));
> + ASSERT_EQ(grand_child, waitpid(grand_child, &status, 0));
> + return;
> + }
> + ASSERT_EQ(0, close(pipe_parent[0]));
> +
> + if (variant->domain_parent == OTHER_SANDBOX)
> + create_fs_domain(_metadata);
> + else if (variant->domain_parent == SCOPE_SANDBOX)
> + create_unix_domain(_metadata);
> +
> + self->parent_server = socket(AF_UNIX, variant->type, 0);
> + ASSERT_NE(-1, self->parent_server);
> + ASSERT_EQ(0, bind(self->parent_server, &self->parent_address.unix_addr,
> + (self->parent_address).unix_addr_len));
> +
> + if (variant->type == SOCK_STREAM)
> + ASSERT_EQ(0, listen(self->parent_server, backlog));
> +
> + ASSERT_EQ(1, write(pipe_parent[1], ".", 1));
> + ASSERT_EQ(child, waitpid(child, &status, 0));
> + if (WIFSIGNALED(status) || !WIFEXITED(status) ||
> + WEXITSTATUS(status) != EXIT_SUCCESS)
> + _metadata->exit_code = KSFT_FAIL;
> +}
> +
> +/*
> + * Since the special case of scoping only happens when the connecting socket
> + * is scoped, the client's domain is true for all the following test cases.
> + */
> +/* clang-format off */
> +FIXTURE(unix_sock_special_cases) {
> + int server_socket, client;
> + int stream_server, stream_client;
Same here, these variables should be local.
> + struct service_fixture address, transit_address;
> +};
> +
> +/* clang-format on */
> +FIXTURE_VARIANT(unix_sock_special_cases)
> +{
> + const bool domain_server;
> + const bool domain_server_socket;
> + const int type;
> +};
> +
> +/* clang-format off */
> +FIXTURE_VARIANT_ADD(unix_sock_special_cases, allow_dgram_server_sock_domain) {
> + /* clang-format on */
> + .domain_server = false,
> + .domain_server_socket = true,
> + .type = SOCK_DGRAM,
> +};
> +
> +/* clang-format off */
> +FIXTURE_VARIANT_ADD(unix_sock_special_cases, deny_dgram_server_domain) {
> + /* clang-format on */
> + .domain_server = true,
> + .domain_server_socket = false,
> + .type = SOCK_DGRAM,
> +};
> +
> +/* clang-format off */
> +FIXTURE_VARIANT_ADD(unix_sock_special_cases, allow_stream_server_sock_domain) {
> + /* clang-format on */
> + .domain_server = false,
> + .domain_server_socket = true,
> + .type = SOCK_STREAM,
> +};
> +
> +/* clang-format off */
> +FIXTURE_VARIANT_ADD(unix_sock_special_cases, deny_stream_server_domain) {
> + /* clang-format on */
> + .domain_server = true,
> + .domain_server_socket = false,
> + .type = SOCK_STREAM,
> +};
> +
> +FIXTURE_SETUP(unix_sock_special_cases)
> +{
> + memset(&self->transit_address, 0, sizeof(self->transit_address));
> + memset(&self->address, 0, sizeof(self->address));
> + set_unix_address(&self->transit_address, 0);
> + set_unix_address(&self->address, 1);
> +}
> +
> +FIXTURE_TEARDOWN(unix_sock_special_cases)
> +{
> + close(self->client);
> + close(self->server_socket);
> + close(self->stream_server);
> + close(self->stream_client);
These EXPECT_EQ(0, close()) calls should be local too.
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