usercopy: Mark kmalloc caches as usercopy caches

Mark the kmalloc slab caches as entirely whitelisted. These caches
are frequently used to fulfill kernel allocations that contain data
to be copied to/from userspace. Internal-only uses are also common,
but are scattered in the kernel. For now, mark all the kmalloc caches
as whitelisted.

This patch is modified from Brad Spengler/PaX Team's PAX_USERCOPY
whitelisting code in the last public patch of grsecurity/PaX based on my
understanding of the code. Changes or omissions from the original code are
mine and don't reflect the original grsecurity/PaX code.

Signed-off-by: David Windsor <dave@nullcore.net>
[kees: merged in moved kmalloc hunks, adjust commit log]
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org
Cc: linux-xfs@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Christoph Lameter <cl@linux.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/mm/slab.h b/mm/slab.h
index 8f3030788e01..1f013f7795c6 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -97,7 +97,8 @@ struct kmem_cache *kmalloc_slab(size_t, gfp_t);
 int __kmem_cache_create(struct kmem_cache *, slab_flags_t flags);
 
 extern struct kmem_cache *create_kmalloc_cache(const char *name, size_t size,
-			slab_flags_t flags);
+			slab_flags_t flags, size_t useroffset,
+			size_t usersize);
 extern void create_boot_cache(struct kmem_cache *, const char *name,
 			size_t size, slab_flags_t flags, size_t useroffset,
 			size_t usersize);