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Subject[PATCH v3 03/31] usercopy: Mark kmalloc caches as usercopy caches
Date
From: David Windsor <dave@nullcore.net>

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: Christoph Lameter <cl@linux.com>
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>
---
mm/slab.c | 3 ++-
mm/slab.h | 3 ++-
mm/slab_common.c | 10 ++++++----
3 files changed, 10 insertions(+), 6 deletions(-)

diff --git a/mm/slab.c b/mm/slab.c
index df268999cf02..9af16f675927 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();

diff --git a/mm/slab.h b/mm/slab.h
index 044755ff9632..2e0fe357d777 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -97,7 +97,8 @@ struct kmem_cache *kmalloc_slab(size_t, gfp_t);
extern int __kmem_cache_create(struct kmem_cache *, unsigned long flags);

extern struct kmem_cache *create_kmalloc_cache(const char *name, size_t size,
- unsigned long flags);
+ unsigned long flags, size_t useroffset,
+ size_t usersize);
extern void create_boot_cache(struct kmem_cache *, const char *name,
size_t size, unsigned long flags, size_t useroffset,
size_t usersize);
diff --git a/mm/slab_common.c b/mm/slab_common.c
index 36408f5f2a34..d4e6442f9bbc 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -920,14 +920,15 @@ 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,
- unsigned long flags)
+ unsigned long 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;
@@ -1081,7 +1082,8 @@ void __init setup_kmalloc_cache_index_table(void)
static void __init new_kmalloc_cache(int idx, unsigned long 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);
}

/*
@@ -1122,7 +1124,7 @@ void __init create_kmalloc_caches(unsigned long 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
--
2.7.4
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