CCing Alejandro On Tue, Feb 27, 2024 at 05:32:20PM +0100, Günther Noack wrote: > On Tue, Feb 27, 2024 at 12:05:49PM +0100, Mickaël Salaün wrote: > > 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 <gno...@google.com> > > Cc: Kees Cook <keesc...@chromium.org> > > Signed-off-by: Mickaël Salaün <m...@digikod.net> > > --- > > > > Changes since v1: > > * New patch, suggested by Kees Cook. > > --- > > Documentation/userspace-api/landlock.rst | 57 +++++++++++++++++++++--- > > 1 file changed, 51 insertions(+), 6 deletions(-) > > > > 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 > > +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. > > I would suggest: s/thanks to/in/
OK > > > +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/.*\(\<lsm=\S\+\).*/\1/p' /proc/cmdline > > + lsm=lockdown,yama,integrity,apparmor > > + > > +...we should configure the bootloader to set a cmdline extending the > > ``lsm`` > > +list with the ``landlock,`` prefix:: > > Nit: Is the double colon at the end of this line accidental? > (It does not appear before the previous code block.) The "::" creates an implicit text block with the following text. For the other block I used an explicit code-block, which then doesn't require this "::". > > > + > > + lsm=landlock,lockdown,yama,integrity,apparmor > > + > > +After a reboot, we can check that Landlock is up and running by looking at > > +kernel logs: > > + > > +.. code-block:: console > > + > > + # dmesg | grep landlock || journalctl -kb -g landlock > > + [ 0.000000] Command line: [...] > > lsm=landlock,lockdown,yama,integrity,apparmor > > + [ 0.000000] Kernel command line: [...] > > lsm=landlock,lockdown,yama,integrity,apparmor > > + [ 0.000000] LSM: initializing > > lsm=lockdown,capability,landlock,yama,integrity,apparmor > > + [ 0.000000] landlock: Up and running. > > + > > +Note that according to the built time kernel configuration, > > s/built time/build time/ > ^ OK > > It feels like the phrase "according to" could be slightly more specific here. > > To paraphrase Alejandro Colomar, "Note that" is usually redundant. > https://lore.kernel.org/all/0aafcdd6-4ac7-8501-c607-9a24a9859...@gmail.com/ > > I'd suggest: > > The kernel may be configured at build time to always load the ``lockdown`` > and > ``capability`` LSMs. In that case, these LSMs will appear at the beginning > of > the ``LSM: initializing`` log line as well, even if they are not configured > in > the boot loader. OK, I integrated your suggestion. I guess `capability` is not really considered an LSM but it would be too confusing and out of scope for an user documentation to explain that. > > > +``lockdown,capability,`` may always stay at the beginning of the ``LSM: > > +initializing lsm=`` list even if they are not configured with the > > bootloader, > > Nit: The man pages spell this in two words as "boot loader". OK, I'll use "boot loader" too. > > > > +which is OK. > > + > > +Network support > > +--------------- > > + > > To be able to explicitly allow TCP operations (e.g., adding a network rule > > with > > ``LANDLOCK_ACCESS_NET_BIND_TCP``), the kernel must support TCP > > (``CONFIG_INET=y``). Otherwise, sys_landlock_add_rule() returns an > > > > base-commit: b4007fd27206c478a4b76e299bddf4a71787f520 > > -- > > 2.44.0 > > > > Reviewed-by: Günther Noack <gno...@google.com> Thanks!
