selftests/landlock: Build without static libraries

The only (forced) static test binary doesn't depend on libcap. Because
using -lcap on systems that don't have such static library would fail
(e.g. on Arch Linux), let's be more specific and require only dynamic
libcap linking.

Fixes: a52540522c95 ("selftests/landlock: Fix out-of-tree builds")
Cc: Anders Roxell <anders.roxell@linaro.org>
Cc: Guillaume Tucker <guillaume.tucker@collabora.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Cc: stable@vger.kernel.org
Signed-off-by: Mickaël Salaün <mic@digikod.net>
Link: https://lore.kernel.org/r/20221019200536.2771316-1-mic@digikod.net

selftests/landlock: Fix out-of-tree builds

These changes simplify the Makefile and handle these 5 ways to build
Landlock tests:
- make -C tools/testing/selftests/landlock
- make -C tools/testing/selftests TARGETS=landlock gen_tar
- make TARGETS=landlock kselftest-gen_tar
- make TARGETS=landlock O=build kselftest-gen_tar
- make -C /tmp/linux TARGETS=landlock O=/tmp/build kselftest-gen_tar

This also makes $(KHDR_INCLUDES) available to other test collections
when building in their directory.

Fixes: f1227dc7d041 ("selftests/landlock: fix broken include of linux/landlock.h")
Fixes: 3bb267a36185 ("selftests: drop khdr make target")
Cc: Anders Roxell <anders.roxell@linaro.org>
Cc: Guillaume Tucker <guillaume.tucker@collabora.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Mickaël Salaün <mic@digikod.net>
Link: https://lore.kernel.org/r/20220909103402.1501802-1-mic@digikod.net

selftests/landlock: fix broken include of linux/landlock.h

Revert part of the earlier changes to fix the kselftest build when
using a sub-directory from the top of the tree as this broke the
landlock test build as a side-effect when building with "make -C
tools/testing/selftests/landlock".

Reported-by: Mickaël Salaün <mic@digikod.net>
Fixes: a917dd94b832 ("selftests/landlock: drop deprecated headers dependency")
Fixes: f2745dc0ba3d ("selftests: stop using KSFT_KHDR_INSTALL")
Signed-off-by: Guillaume Tucker <guillaume.tucker@collabora.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

selftests/landlock: drop deprecated headers dependency

The khdr make target has been removed, so drop it from the landlock
Makefile dependencies as well as related include paths that are
standard for headers in the kernel tree.

Signed-off-by: Guillaume Tucker <guillaume.tucker@collabora.com>
Reported-by: Anders Roxell <anders.roxell@linaro.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

selftests: stop using KSFT_KHDR_INSTALL

Stop using the KSFT_KHDR_INSTALL flag as installing the kernel headers
from the kselftest Makefile is causing some issues. Instead, rely on
the headers to be installed directly by the top-level Makefile
"headers_install" make target prior to building kselftest.

Signed-off-by: Guillaume Tucker <guillaume.tucker@collabora.com>
Tested-by: Anders Roxell <anders.roxell@linaro.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

selftests: landlock: Add the uapi headers include variable

Out of tree build of this test fails if relative path of the output
directory is specified. Add the KHDR_INCLUDES to correctly reach the
headers.

Signed-off-by: Muhammad Usama Anjum <usama.anjum@collabora.com>
Reviewed-by: Mickaël Salaün <mic@linux.microsoft.com>
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>