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    Subject[PATCH 06/36] 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 d9939828f8e4..6488066e718a 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 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);
    diff --git a/mm/slab_common.c b/mm/slab_common.c
    index fc3e66bdce75..6c9e945907b6 100644
    --- a/mm/slab_common.c
    +++ b/mm/slab_common.c
    @@ -929,14 +929,15 @@ 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;
    @@ -1090,7 +1091,8 @@ 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);
    }

    /*
    @@ -1131,7 +1133,7 @@ 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
    --
    2.7.4
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