Commit 6c0c21ad authored by David Windsor's avatar David Windsor Committed by Kees Cook
Browse files

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: default avatarDavid 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: default avatarKees Cook <keescook@chromium.org>
Acked-by: default avatarChristoph Lameter <cl@linux.com>
parent 2d891fbc

mm/slab.c

+2 −1
Original line number Diff line number Diff line
@@ -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();

mm/slab.h

+2 −1
Original line number Diff line number Diff line
@@ -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);

mm/slab_common.c

+6 −4
Original line number Diff line number Diff line
@@ -937,14 +937,15 @@ void __init create_boot_cache(struct kmem_cache *s, const char *name, size_t siz 
}



struct kmem_cache *__init create_kmalloc_cache(const char *name, size_t size,

				slab_flags_t flags)

				slab_flags_t flags, size_t useroffset,

				size_t usersize)

{

	struct kmem_cache *s = kmem_cache_zalloc(kmem_cache, GFP_NOWAIT);



	if (!s)

		panic("Out of memory when creating slab %s\n", name);



	create_boot_cache(s, name, size, flags, 0, size);

	create_boot_cache(s, name, size, flags, useroffset, usersize);

	list_add(&s->list, &slab_caches);

	memcg_link_cache(s);

	s->refcount = 1;
@@ -1098,7 +1099,8 @@ void __init setup_kmalloc_cache_index_table(void) 
static void __init new_kmalloc_cache(int idx, slab_flags_t flags)

{

	kmalloc_caches[idx] = create_kmalloc_cache(kmalloc_info[idx].name,

					kmalloc_info[idx].size, flags);

					kmalloc_info[idx].size, flags, 0,

					kmalloc_info[idx].size);

}



/*
@@ -1139,7 +1141,7 @@ void __init create_kmalloc_caches(slab_flags_t flags) 


			BUG_ON(!n);

			kmalloc_dma_caches[i] = create_kmalloc_cache(n,

				size, SLAB_CACHE_DMA | flags);

				size, SLAB_CACHE_DMA | flags, 0, 0);

		}

	}

#endif

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