On Mon, Feb 19, 2024 at 01:07:48PM -0800, Kees Cook wrote:
On Mon, Feb 19, 2024 at 08:18:04PM +0100, Mickaël Salaün wrote:
Because sandboxing can be used as an opportunistic security measure, user space may not log unsupported features. Let the system administrator know if an application tries to use Landlock but failed because it isn't enabled at boot time. This may be caused by bootloader configurations with outdated "lsm" kernel's command-line parameter.
Cc: Günther Noack gnoack@google.com Cc: stable@vger.kernel.org Fixes: 265885daf3e5 ("landlock: Add syscall implementations") Signed-off-by: Mickaël Salaün mic@digikod.net
security/landlock/syscalls.c | 18 +++++++++++++++--- 1 file changed, 15 insertions(+), 3 deletions(-)
diff --git a/security/landlock/syscalls.c b/security/landlock/syscalls.c index f0bc50003b46..b5b424819dee 100644 --- a/security/landlock/syscalls.c +++ b/security/landlock/syscalls.c @@ -33,6 +33,18 @@ #include "ruleset.h" #include "setup.h" +static bool is_not_initialized(void) +{
- if (likely(landlock_initialized))
return false;- pr_warn_once(
"Disabled but requested by user space. ""You should enable Landlock at boot time: ""https://docs.kernel.org/userspace-api/landlock.html#kernel-support\n");Perhaps update this docs to be really explicit with a example, maybe...
If `landlock` is not present in `CONFIG_LSM`, you can add it. For example, if this was the current config::
$ zgrep -h ^CONFIG_LSM= /boot/config-$(uname -r) /proc/config.gz 2>/dev/null CONFIG_LSM="lockdown,yama,integrity,apparmor"
You can boot with::
lsm=landlock,lockdown,yama,integrity,apparmor
Indeed, I'll send a dedicated patch and update the link accordingly.
I *still* wish we had the "+" operator for lsm=. It would be SO much easier to say "boot with lsm=+landlock". *shrug*
I guess it's still possible and it would need to be backported to be more useful.
Reviewed-by: Kees Cook keescook@chromium.org
-- Kees Cook