selftests/landlock: Clean up error logs related to capabilities

It doesn't help to call TH_LOG() for every cap_*() error. Let's only
log errors returned by the kernel, not by libcap specificities.

Link: https://lore.kernel.org/r/20240125153230.3817165-3-mic@digikod.net
Signed-off-by: Mickaël Salaün <mic@digikod.net>

selftests/harness: Merge TEST_F_FORK() into TEST_F()

Replace Landlock-specific TEST_F_FORK() with an improved TEST_F() which
brings four related changes:

Run TEST_F()'s tests in a grandchild process to make it possible to
drop privileges and delegate teardown to the parent.

Compared to TEST_F_FORK(), simplify handling of the test grandchild
process thanks to vfork(2), and makes it generic (e.g. no explicit
conversion between exit code and _metadata).

Compared to TEST_F_FORK(), run teardown even when tests failed with an
assert thanks to commit 63e6b2a42342 ("selftests/harness: Run TEARDOWN
for ASSERT failures").

Simplify the test harness code by removing the no_print and step fields
which are not used. I added this feature just after I made
kselftest_harness.h more broadly available but this step counter
remained even though it wasn't needed after all. See commit 369130b63178
("selftests: Enhance kselftest_harness.h to print which assert failed").

Replace spaces with tabs in one line of __TEST_F_IMPL().

Cc: Günther Noack <gnoack@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Will Drewry <wad@chromium.org>
Signed-off-by: Mickaël Salaün <mic@digikod.net>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

selftests/landlock: Redefine TEST_F() as TEST_F_FORK()

This has the effect of creating a new test process for either TEST_F()
or TEST_F_FORK(), which doesn't change tests but will ease potential
backports. See next commit for the TEST_F_FORK() merge into TEST_F().

Cc: Günther Noack <gnoack@google.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Will Drewry <wad@chromium.org>
Signed-off-by: Mickaël Salaün <mic@digikod.net>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

selftests/landlock: Fix capability for net_test

CAP_NET_ADMIN allows to configure network interfaces, not CAP_SYS_ADMIN
which only allows to call unshare(2). Without this change, running
network tests as a non-root user but with all capabilities would fail at
the setup_loopback() step with "RTNETLINK answers: Operation not
permitted".

The issue is only visible when running tests with non-root users (i.e.
only relying on ambient capabilities). Indeed, when configuring the
network interface, the "ip" command is called, which may lead to the
special handling of capabilities for the root user by execve(2). If
root is the caller, then the inherited, permitted and effective
capabilities are all reset, which then includes CAP_NET_ADMIN. However,
if a non-root user is the caller, then ambient capabilities are masked
by the inherited ones, which were explicitly dropped.

To make execution deterministic whatever users are running the tests,
set the noroot secure bit for each test, and set the inheritable and
ambient capabilities to CAP_NET_ADMIN, the only capability that may be
required after an execve(2).

Factor out _effective_cap() into _change_cap(), and use it to manage
ambient capabilities with the new set_ambient_cap() and
clear_ambient_cap() helpers.

This makes it possible to run all Landlock tests with check-linux.sh
from https://github.com/landlock-lsm/landlock-test-tools

Cc: Konstantin Meskhidze <konstantin.meskhidze@huawei.com>
Fixes: a549d055a22e ("selftests/landlock: Add network tests")
Link: https://lore.kernel.org/r/20240125153230.3817165-2-mic@digikod.net
[mic: Make sure SECBIT_NOROOT_LOCKED is set]
Signed-off-by: Mickaël Salaün <mic@digikod.net>

selftests/landlock: Add network tests

Add 82 test suites to check edge cases related to bind() and connect()
actions. They are defined with 6 fixtures and their variants:

The "protocol" fixture is extended with 12 variants defined as a matrix
of: sandboxed/not-sandboxed, IPv4/IPv6/unix network domain, and
stream/datagram socket. 4 related tests suites are defined:
* bind: Tests bind action.
* connect: Tests connect action.
* bind_unspec: Tests bind action with the AF_UNSPEC socket family.
* connect_unspec: Tests connect action with the AF_UNSPEC socket family.

The "ipv4" fixture is extended with 4 variants defined as a matrix
of: sandboxed/not-sandboxed, and stream/datagram socket. 1 related test
suite is defined:
* from_unix_to_inet: Tests to make sure unix sockets' actions are not
restricted by Landlock rules applied to TCP ones.

The "tcp_layers" fixture is extended with 8 variants defined as a matrix
of: IPv4/IPv6 network domain, and different number of landlock rule
layers. 2 related tests suites are defined:
* ruleset_overlap: Tests nested layers with less constraints.
* ruleset_expand: Tests nested layers with more constraints.

In the "mini" fixture 4 tests suites are defined:
* network_access_rights: Tests handling of known access rights.
* unknown_access_rights: Tests handling of unknown access rights.
* inval: Tests unhandled allowed access and zero access value.
* tcp_port_overflow: Tests with port values greater than 65535.

The "ipv4_tcp" fixture supports IPv4 network domain with stream socket.
2 tests suites are defined:
* port_endianness: Tests with big/little endian port formats.
* with_fs: Tests a ruleset with both filesystem and network
restrictions.

The "port_specific" fixture is extended with 4 variants defined
as a matrix of: sandboxed/not-sandboxed, IPv4/IPv6 network domain,
and stream socket. 2 related tests suites are defined:
* bind_connect_zero: Tests with port 0.
* bind_connect_1023: Tests with port 1023.

Test coverage for security/landlock is 92.4% of 710 lines according to
gcc/gcov-13.

Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@huawei.com>
Link: https://lore.kernel.org/r/20231026014751.414649-11-konstantin.meskhidze@huawei.com
[mic: Extend commit message, update test coverage, clean up capability
use, fix useless TEST_F_FORK, and improve ipv4_tcp.with_fs]
Co-developed-by: Mickaël Salaün <mic@digikod.net>
Signed-off-by: Mickaël Salaün <mic@digikod.net>

selftests/landlock: Share enforce_ruleset() helper

Move enforce_ruleset() helper function to common.h so that it can be
used both by filesystem tests and network ones.

Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@huawei.com>
Link: https://lore.kernel.org/r/20231026014751.414649-10-konstantin.meskhidze@huawei.com
Signed-off-by: Mickaël Salaün <mic@digikod.net>

selftests/landlock: Test FD passing from restricted to unrestricted processes

A file descriptor created in a restricted process carries Landlock
restrictions with it which will apply even if the same opened file is
used from an unrestricted process.

This change extracts suitable FD-passing helpers from base_test.c and
moves them to common.h. We use the fixture variants from the ftruncate
fixture to exercise the same scenarios as in the open_and_ftruncate
test, but doing the Landlock restriction and open() in a different
process than the ftruncate() call.

Signed-off-by: Günther Noack <gnoack3000@gmail.com>
Link: https://lore.kernel.org/r/20221018182216.301684-9-gnoack3000@gmail.com
Signed-off-by: Mickaël Salaün <mic@digikod.net>

selftests/landlock: Locally define __maybe_unused

The checkpatch tool started to flag __attribute__(__unused__), which
we previously used. The header where this is normally defined is not
currently compatible with selftests.

This is the same approach as used in selftests/net/psock_lib.h.

Signed-off-by: Günther Noack <gnoack3000@gmail.com>
Link: https://lore.kernel.org/r/20221018182216.301684-8-gnoack3000@gmail.com
Signed-off-by: Mickaël Salaün <mic@digikod.net>

selftests/landlock: Format with clang-format

Let's follow a consistent and documented coding style. Everything may
not be to our liking but it is better than tacit knowledge. Moreover,
this will help maintain style consistency between different developers.

This contains only whitespace changes.

Automatically formatted with:
clang-format-14 -i tools/testing/selftests/landlock/*.[ch]

Link: https://lore.kernel.org/r/20220506160513.523257-6-mic@digikod.net
Cc: stable@vger.kernel.org
[mic: Update style according to
https://lore.kernel.org/r/02494cb8-2aa5-1769-f28d-d7206f284e5a@digikod.net]
Signed-off-by: Mickaël Salaün <mic@digikod.net>

selftests/landlock: Add clang-format exceptions

In preparation to a following commit, add clang-format on and
clang-format off stanzas around constant definitions and the TEST_F_FORK
macro. This enables to keep aligned values, which is much more readable
than packed definitions.

Add other clang-format exceptions for FIXTURE() and
FIXTURE_VARIANT_ADD() declarations to force space before open brace,
which is reported by checkpatch.pl .

Link: https://lore.kernel.org/r/20220506160513.523257-4-mic@digikod.net
Cc: stable@vger.kernel.org
Signed-off-by: Mickaël Salaün <mic@digikod.net>

selftests/landlock: remove ARRAY_SIZE define from common.h

ARRAY_SIZE is defined in several selftests. Remove definitions from
individual test files and include header file for the define instead.
ARRAY_SIZE define is added in a separate patch to prepare for this
change.

Remove ARRAY_SIZE from common.h and pickup the one defined in
kselftest.h.

Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

selftests/landlock: Add user space tests

Test all Landlock system calls, ptrace hooks semantic and filesystem
access-control with multiple layouts.

Test coverage for security/landlock/ is 93.6% of lines. The code not
covered only deals with internal kernel errors (e.g. memory allocation)
and race conditions.

Cc: James Morris <jmorris@namei.org>
Cc: Jann Horn <jannh@google.com>
Cc: Serge E. Hallyn <serge@hallyn.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Mickaël Salaün <mic@linux.microsoft.com>
Reviewed-by: Vincent Dagonneau <vincent.dagonneau@ssi.gouv.fr>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210422154123.13086-11-mic@digikod.net
Signed-off-by: James Morris <jamorris@linux.microsoft.com>