From: keescook@chromium.org (Kees Cook)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v4 12/12] mm: SLUB hardened usercopy support
Date: Wed, 20 Jul 2016 13:27:07 -0700 [thread overview]
Message-ID: <1469046427-12696-13-git-send-email-keescook@chromium.org> (raw)
In-Reply-To: <1469046427-12696-1-git-send-email-keescook@chromium.org>
Under CONFIG_HARDENED_USERCOPY, this adds object size checking to the
SLUB allocator to catch any copies that may span objects. Includes a
redzone handling fix discovered by Michael Ellerman.
Based on code from PaX and grsecurity.
Signed-off-by: Kees Cook <keescook@chromium.org>
Tested-by: Michael Ellerman <mpe@ellerman.id.au>
---
init/Kconfig | 1 +
mm/slub.c | 36 ++++++++++++++++++++++++++++++++++++
2 files changed, 37 insertions(+)
diff --git a/init/Kconfig b/init/Kconfig
index 798c2020ee7c..1c4711819dfd 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1765,6 +1765,7 @@ config SLAB
config SLUB
bool "SLUB (Unqueued Allocator)"
+ select HAVE_HARDENED_USERCOPY_ALLOCATOR
help
SLUB is a slab allocator that minimizes cache line usage
instead of managing queues of cached objects (SLAB approach).
diff --git a/mm/slub.c b/mm/slub.c
index 825ff4505336..7dee3d9a5843 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -3614,6 +3614,42 @@ void *__kmalloc_node(size_t size, gfp_t flags, int node)
EXPORT_SYMBOL(__kmalloc_node);
#endif
+#ifdef CONFIG_HARDENED_USERCOPY
+/*
+ * Rejects objects that are incorrectly sized.
+ *
+ * Returns NULL if check passes, otherwise const char * to name of cache
+ * to indicate an error.
+ */
+const char *__check_heap_object(const void *ptr, unsigned long n,
+ struct page *page)
+{
+ struct kmem_cache *s;
+ unsigned long offset;
+ size_t object_size;
+
+ /* Find object and usable object size. */
+ s = page->slab_cache;
+ object_size = slab_ksize(s);
+
+ /* Find offset within object. */
+ offset = (ptr - page_address(page)) % s->size;
+
+ /* Adjust for redzone and reject if within the redzone. */
+ if (kmem_cache_debug(s) && s->flags & SLAB_RED_ZONE) {
+ if (offset < s->red_left_pad)
+ return s->name;
+ offset -= s->red_left_pad;
+ }
+
+ /* Allow address range falling entirely within object size. */
+ if (offset <= object_size && n <= object_size - offset)
+ return NULL;
+
+ return s->name;
+}
+#endif /* CONFIG_HARDENED_USERCOPY */
+
static size_t __ksize(const void *object)
{
struct page *page;
--
2.7.4
next prev parent reply other threads:[~2016-07-20 20:27 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-20 20:26 [PATCH v4 00/12] mm: Hardened usercopy Kees Cook
2016-07-20 20:26 ` [PATCH v4 01/12] mm: Add is_migrate_cma_page Kees Cook
2016-07-20 20:26 ` [PATCH v4 02/12] mm: Implement stack frame object validation Kees Cook
2016-07-20 20:26 ` [PATCH v4 03/12] mm: Hardened usercopy Kees Cook
2016-07-20 20:26 ` [PATCH v4 04/12] x86/uaccess: Enable hardened usercopy Kees Cook
2016-07-20 20:27 ` [PATCH v4 05/12] ARM: uaccess: " Kees Cook
2016-07-20 20:27 ` [PATCH v4 06/12] arm64/uaccess: " Kees Cook
2016-07-20 20:27 ` [PATCH v4 07/12] ia64/uaccess: " Kees Cook
2016-07-20 20:27 ` [PATCH v4 08/12] powerpc/uaccess: " Kees Cook
2016-07-20 20:27 ` [PATCH v4 09/12] sparc/uaccess: " Kees Cook
2016-07-20 20:27 ` [PATCH v4 10/12] s390/uaccess: " Kees Cook
2016-07-20 20:27 ` [PATCH v4 11/12] mm: SLAB hardened usercopy support Kees Cook
2016-07-20 20:27 ` Kees Cook [this message]
2016-07-25 19:16 ` [PATCH v4 12/12] mm: SLUB " Laura Abbott
2016-07-25 20:45 ` Kees Cook
2016-07-26 0:54 ` Laura Abbott
2016-07-25 21:42 ` Rik van Riel
2016-07-25 23:29 ` Laura Abbott
2016-07-26 0:22 ` Rik van Riel
2016-07-23 0:36 ` [PATCH v4 00/12] mm: Hardened usercopy Laura Abbott
2016-07-25 17:50 ` Kees Cook
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