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.c b/mm/slab.c
index b9b0df620bb9..dd367fe17a4e 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -1291,7 +1291,8 @@ void __init kmem_cache_init(void)
 	 */
 	kmalloc_caches[INDEX_NODE] = create_kmalloc_cache(
 				kmalloc_info[INDEX_NODE].name,
-				kmalloc_size(INDEX_NODE), ARCH_KMALLOC_FLAGS);
+				kmalloc_size(INDEX_NODE), ARCH_KMALLOC_FLAGS,
+				0, kmalloc_size(INDEX_NODE));
 	slab_state = PARTIAL_NODE;
 	setup_kmalloc_cache_index_table();