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Hallyn" Cc: =?utf-8?q?Micka=C3=ABl_Sala=C3=BCn?= , Konstantin Meskhidze , Shervin Oloumi , linux-hardening@vger.kernel.org, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, Kees Cook Subject: [PATCH v2 1/2] landlock: Extend documentation for kernel support Date: Tue, 27 Feb 2024 12:05:49 +0100 Message-ID: <20240227110550.3702236-1-mic@digikod.net> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Infomaniak-Routing: alpha X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1792050532797570273 X-GMAIL-MSGID: 1792050532797570273 Extend the kernel support section with one subsection for build time configuration and another for boot time configuration. Extend the boot time subsection with a concrete example. Update the journalctl command to include the boot option. Cc: Günther Noack Cc: Kees Cook Signed-off-by: Mickaël Salaün Reviewed-by: Günther Noack --- Changes since v1: * New patch, suggested by Kees Cook. --- Documentation/userspace-api/landlock.rst | 57 +++++++++++++++++++++--- 1 file changed, 51 insertions(+), 6 deletions(-) base-commit: b4007fd27206c478a4b76e299bddf4a71787f520 diff --git a/Documentation/userspace-api/landlock.rst b/Documentation/userspace-api/landlock.rst index 2e3822677061..838cc27db232 100644 --- a/Documentation/userspace-api/landlock.rst +++ b/Documentation/userspace-api/landlock.rst @@ -19,11 +19,12 @@ unexpected/malicious behaviors in user space applications. Landlock empowers any process, including unprivileged ones, to securely restrict themselves. We can quickly make sure that Landlock is enabled in the running system by -looking for "landlock: Up and running" in kernel logs (as root): ``dmesg | grep -landlock || journalctl -kg landlock`` . Developers can also easily check for -Landlock support with a :ref:`related system call `. If -Landlock is not currently supported, we need to :ref:`configure the kernel -appropriately `. +looking for "landlock: Up and running" in kernel logs (as root): +``dmesg | grep landlock || journalctl -kb -g landlock`` . +Developers can also easily check for Landlock support with a +:ref:`related system call `. +If Landlock is not currently supported, we need to +:ref:`configure the kernel appropriately `. Landlock rules ============== @@ -499,6 +500,9 @@ access rights. Kernel support ============== +Build time configuration +------------------------ + Landlock was first introduced in Linux 5.13 but it must be configured at build time with ``CONFIG_SECURITY_LANDLOCK=y``. Landlock must also be enabled at boot time as the other security modules. The list of security modules enabled by @@ -507,11 +511,52 @@ contains ``CONFIG_LSM=landlock,[...]`` with ``[...]`` as the list of other potentially useful security modules for the running system (see the ``CONFIG_LSM`` help). +Boot time configuration +----------------------- + If the running kernel does not have ``landlock`` in ``CONFIG_LSM``, then we can -still enable it by adding ``lsm=landlock,[...]`` to +enable Landlock by adding ``lsm=landlock,[...]`` to Documentation/admin-guide/kernel-parameters.rst thanks to the bootloader configuration. +For example, if the current built-in configuration is: + +.. code-block:: console + + $ zgrep -h "^CONFIG_LSM=" "/boot/config-$(uname -r)" /proc/config.gz 2>/dev/null + CONFIG_LSM="lockdown,yama,integrity,apparmor" + +...and if the cmdline doesn't contain ``landlock`` either: + +.. code-block:: console + + $ sed -n 's/.*\(\