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Date: Mon, 13 Jun 2022 22:14:03 +0200
From: andrey.konovalov@...ux.dev
To: Marco Elver <elver@...gle.com>,
Alexander Potapenko <glider@...gle.com>
Cc: Andrey Konovalov <andreyknvl@...il.com>,
Dmitry Vyukov <dvyukov@...gle.com>,
Andrey Ryabinin <ryabinin.a.a@...il.com>,
kasan-dev@...glegroups.com, Peter Collingbourne <pcc@...gle.com>,
Evgenii Stepanov <eugenis@...gle.com>,
Florian Mayer <fmayer@...gle.com>,
Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
linux-kernel@...r.kernel.org,
Andrey Konovalov <andreyknvl@...gle.com>
Subject: [PATCH 12/32] kasan: introduce kasan_init_cache_meta
From: Andrey Konovalov <andreyknvl@...gle.com>
Add a kasan_init_cache_meta() helper that initializes metadata-related
cache parameters and use this helper in the common KASAN code.
Put the implementation of this new helper into generic.c, as only the
Generic mode uses per-object metadata.
Signed-off-by: Andrey Konovalov <andreyknvl@...gle.com>
---
mm/kasan/common.c | 80 ++--------------------------------------------
mm/kasan/generic.c | 79 +++++++++++++++++++++++++++++++++++++++++++++
mm/kasan/kasan.h | 2 ++
3 files changed, 83 insertions(+), 78 deletions(-)
diff --git a/mm/kasan/common.c b/mm/kasan/common.c
index a3dee7cead89..8a83ca9ad738 100644
--- a/mm/kasan/common.c
+++ b/mm/kasan/common.c
@@ -117,28 +117,9 @@ void __kasan_poison_pages(struct page *page, unsigned int order, bool init)
KASAN_PAGE_FREE, init);
}
-/*
- * Adaptive redzone policy taken from the userspace AddressSanitizer runtime.
- * For larger allocations larger redzones are used.
- */
-static inline unsigned int optimal_redzone(unsigned int object_size)
-{
- return
- object_size <= 64 - 16 ? 16 :
- object_size <= 128 - 32 ? 32 :
- object_size <= 512 - 64 ? 64 :
- object_size <= 4096 - 128 ? 128 :
- object_size <= (1 << 14) - 256 ? 256 :
- object_size <= (1 << 15) - 512 ? 512 :
- object_size <= (1 << 16) - 1024 ? 1024 : 2048;
-}
-
void __kasan_cache_create(struct kmem_cache *cache, unsigned int *size,
slab_flags_t *flags)
{
- unsigned int ok_size;
- unsigned int optimal_size;
-
/*
* SLAB_KASAN is used to mark caches as ones that are sanitized by
* KASAN. Currently this flag is used in two places:
@@ -148,65 +129,8 @@ void __kasan_cache_create(struct kmem_cache *cache, unsigned int *size,
*/
*flags |= SLAB_KASAN;
- if (!kasan_requires_meta())
- return;
-
- ok_size = *size;
-
- /* Add alloc meta into redzone. */
- cache->kasan_info.alloc_meta_offset = *size;
- *size += sizeof(struct kasan_alloc_meta);
-
- /*
- * If alloc meta doesn't fit, don't add it.
- * This can only happen with SLAB, as it has KMALLOC_MAX_SIZE equal
- * to KMALLOC_MAX_CACHE_SIZE and doesn't fall back to page_alloc for
- * larger sizes.
- */
- if (*size > KMALLOC_MAX_SIZE) {
- cache->kasan_info.alloc_meta_offset = 0;
- *size = ok_size;
- /* Continue, since free meta might still fit. */
- }
-
- /* Only the generic mode uses free meta or flexible redzones. */
- if (!IS_ENABLED(CONFIG_KASAN_GENERIC)) {
- cache->kasan_info.free_meta_offset = KASAN_NO_FREE_META;
- return;
- }
-
- /*
- * Add free meta into redzone when it's not possible to store
- * it in the object. This is the case when:
- * 1. Object is SLAB_TYPESAFE_BY_RCU, which means that it can
- * be touched after it was freed, or
- * 2. Object has a constructor, which means it's expected to
- * retain its content until the next allocation, or
- * 3. Object is too small.
- * Otherwise cache->kasan_info.free_meta_offset = 0 is implied.
- */
- if ((cache->flags & SLAB_TYPESAFE_BY_RCU) || cache->ctor ||
- cache->object_size < sizeof(struct kasan_free_meta)) {
- ok_size = *size;
-
- cache->kasan_info.free_meta_offset = *size;
- *size += sizeof(struct kasan_free_meta);
-
- /* If free meta doesn't fit, don't add it. */
- if (*size > KMALLOC_MAX_SIZE) {
- cache->kasan_info.free_meta_offset = KASAN_NO_FREE_META;
- *size = ok_size;
- }
- }
-
- /* Calculate size with optimal redzone. */
- optimal_size = cache->object_size + optimal_redzone(cache->object_size);
- /* Limit it with KMALLOC_MAX_SIZE (relevant for SLAB only). */
- if (optimal_size > KMALLOC_MAX_SIZE)
- optimal_size = KMALLOC_MAX_SIZE;
- /* Use optimal size if the size with added metas is not large enough. */
- if (*size < optimal_size)
- *size = optimal_size;
+ if (kasan_requires_meta())
+ kasan_init_cache_meta(cache, size);
}
void __kasan_cache_create_kmalloc(struct kmem_cache *cache)
diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c
index fa654cb96a0d..73aea784040a 100644
--- a/mm/kasan/generic.c
+++ b/mm/kasan/generic.c
@@ -328,6 +328,85 @@ DEFINE_ASAN_SET_SHADOW(f3);
DEFINE_ASAN_SET_SHADOW(f5);
DEFINE_ASAN_SET_SHADOW(f8);
+/*
+ * Adaptive redzone policy taken from the userspace AddressSanitizer runtime.
+ * For larger allocations larger redzones are used.
+ */
+static inline unsigned int optimal_redzone(unsigned int object_size)
+{
+ return
+ object_size <= 64 - 16 ? 16 :
+ object_size <= 128 - 32 ? 32 :
+ object_size <= 512 - 64 ? 64 :
+ object_size <= 4096 - 128 ? 128 :
+ object_size <= (1 << 14) - 256 ? 256 :
+ object_size <= (1 << 15) - 512 ? 512 :
+ object_size <= (1 << 16) - 1024 ? 1024 : 2048;
+}
+
+void kasan_init_cache_meta(struct kmem_cache *cache, unsigned int *size)
+{
+ unsigned int ok_size;
+ unsigned int optimal_size;
+
+ ok_size = *size;
+
+ /* Add alloc meta into redzone. */
+ cache->kasan_info.alloc_meta_offset = *size;
+ *size += sizeof(struct kasan_alloc_meta);
+
+ /*
+ * If alloc meta doesn't fit, don't add it.
+ * This can only happen with SLAB, as it has KMALLOC_MAX_SIZE equal
+ * to KMALLOC_MAX_CACHE_SIZE and doesn't fall back to page_alloc for
+ * larger sizes.
+ */
+ if (*size > KMALLOC_MAX_SIZE) {
+ cache->kasan_info.alloc_meta_offset = 0;
+ *size = ok_size;
+ /* Continue, since free meta might still fit. */
+ }
+
+ /* Only the generic mode uses free meta or flexible redzones. */
+ if (!IS_ENABLED(CONFIG_KASAN_GENERIC)) {
+ cache->kasan_info.free_meta_offset = KASAN_NO_FREE_META;
+ return;
+ }
+
+ /*
+ * Add free meta into redzone when it's not possible to store
+ * it in the object. This is the case when:
+ * 1. Object is SLAB_TYPESAFE_BY_RCU, which means that it can
+ * be touched after it was freed, or
+ * 2. Object has a constructor, which means it's expected to
+ * retain its content until the next allocation, or
+ * 3. Object is too small.
+ * Otherwise cache->kasan_info.free_meta_offset = 0 is implied.
+ */
+ if ((cache->flags & SLAB_TYPESAFE_BY_RCU) || cache->ctor ||
+ cache->object_size < sizeof(struct kasan_free_meta)) {
+ ok_size = *size;
+
+ cache->kasan_info.free_meta_offset = *size;
+ *size += sizeof(struct kasan_free_meta);
+
+ /* If free meta doesn't fit, don't add it. */
+ if (*size > KMALLOC_MAX_SIZE) {
+ cache->kasan_info.free_meta_offset = KASAN_NO_FREE_META;
+ *size = ok_size;
+ }
+ }
+
+ /* Calculate size with optimal redzone. */
+ optimal_size = cache->object_size + optimal_redzone(cache->object_size);
+ /* Limit it with KMALLOC_MAX_SIZE (relevant for SLAB only). */
+ if (optimal_size > KMALLOC_MAX_SIZE)
+ optimal_size = KMALLOC_MAX_SIZE;
+ /* Use optimal size if the size with added metas is not large enough. */
+ if (*size < optimal_size)
+ *size = optimal_size;
+}
+
struct kasan_alloc_meta *kasan_get_alloc_meta(struct kmem_cache *cache,
const void *object)
{
diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
index cf123d99f2fe..ab2cd3ff10f3 100644
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h
@@ -296,12 +296,14 @@ struct page *kasan_addr_to_page(const void *addr);
struct slab *kasan_addr_to_slab(const void *addr);
#ifdef CONFIG_KASAN_GENERIC
+void kasan_init_cache_meta(struct kmem_cache *cache, unsigned int *size);
void kasan_init_object_meta(struct kmem_cache *cache, const void *object);
struct kasan_alloc_meta *kasan_get_alloc_meta(struct kmem_cache *cache,
const void *object);
struct kasan_free_meta *kasan_get_free_meta(struct kmem_cache *cache,
const void *object);
#else
+static inline void kasan_init_cache_meta(struct kmem_cache *cache, unsigned int *size) { }
static inline void kasan_init_object_meta(struct kmem_cache *cache, const void *object) { }
#endif
--
2.25.1
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