usercopy: Allow strict enforcement of whitelists
This introduces CONFIG_HARDENED_USERCOPY_FALLBACK to control the
behavior of hardened usercopy whitelist violations. By default, whitelist
violations will continue to WARN() so that any bad or missing usercopy
whitelists can be discovered without being too disruptive.
If this config is disabled at build time or a system is booted with
"slab_common.usercopy_fallback=0", usercopy whitelists will BUG() instead
of WARN(). This is useful for admins that want to use usercopy whitelists
immediately.
Suggested-by: Matthew Garrett <mjg59@google.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
diff --git a/include/linux/slab.h b/include/linux/slab.h
index 8bf14d9..231abc8 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -135,6 +135,8 @@ struct mem_cgroup;
void __init kmem_cache_init(void);
bool slab_is_available(void);
+extern bool usercopy_fallback;
+
struct kmem_cache *kmem_cache_create(const char *name, size_t size,
size_t align, slab_flags_t flags,
void (*ctor)(void *));