6.8-stable review patch. If anyone has any objections, please let me know.
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From: Mickaël Salaün mic@digikod.net
[ Upstream commit 782191c74875cc33b50263e21d76080b1411884d ]
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 This may be caused by boot loader configurations with outdated "lsm" kernel's command-line parameter.
Cc: stable@vger.kernel.org Fixes: 265885daf3e5 ("landlock: Add syscall implementations") Reviewed-by: Kees Cook keescook@chromium.org Reviewed-by: Günther Noack gnoack3000@gmail.com Link: https://lore.kernel.org/r/20240227110550.3702236-2-mic@digikod.net Signed-off-by: Mickaël Salaün mic@digikod.net Signed-off-by: Sasha Levin sashal@kernel.org --- 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 898358f57fa08..6788e73b6681b 100644 --- a/security/landlock/syscalls.c +++ b/security/landlock/syscalls.c @@ -33,6 +33,18 @@ #include "ruleset.h" #include "setup.h"
+static bool is_initialized(void) +{ + if (likely(landlock_initialized)) + return true; + + pr_warn_once( + "Disabled but requested by user space. " + "You should enable Landlock at boot time: " + "https://docs.kernel.org/userspace-api/landlock.html#boot-time-configuration%..."); + return false; +} + /** * copy_min_struct_from_user - Safe future-proof argument copying * @@ -173,7 +185,7 @@ SYSCALL_DEFINE3(landlock_create_ruleset, /* Build-time checks. */ build_check_abi();
- if (!landlock_initialized) + if (!is_initialized()) return -EOPNOTSUPP;
if (flags) { @@ -398,7 +410,7 @@ SYSCALL_DEFINE4(landlock_add_rule, const int, ruleset_fd, struct landlock_ruleset *ruleset; int err;
- if (!landlock_initialized) + if (!is_initialized()) return -EOPNOTSUPP;
/* No flag for now. */ @@ -458,7 +470,7 @@ SYSCALL_DEFINE2(landlock_restrict_self, const int, ruleset_fd, const __u32, struct landlock_cred_security *new_llcred; int err;
- if (!landlock_initialized) + if (!is_initialized()) return -EOPNOTSUPP;
/*