[PATCH RFC v2 15/21] kasan: check kasan_enabled in annotations
Dmitry Vyukov
dvyukov at google.com
Wed Oct 28 12:47:39 EDT 2020
On Thu, Oct 22, 2020 at 3:20 PM Andrey Konovalov <andreyknvl at google.com> wrote:
>
> Declare the kasan_enabled static key in include/linux/kasan.h and in
> include/linux/mm.h and check it in all kasan annotations. This allows to
> avoid any slowdown caused by function calls when kasan_enabled is
> disabled.
>
> Signed-off-by: Andrey Konovalov <andreyknvl at google.com>
> Link: https://linux-review.googlesource.com/id/I2589451d3c96c97abbcbf714baabe6161c6f153e
> ---
> include/linux/kasan.h | 210 ++++++++++++++++++++++++++++++++----------
> include/linux/mm.h | 27 ++++--
> mm/kasan/common.c | 60 ++++++------
> 3 files changed, 211 insertions(+), 86 deletions(-)
>
> diff --git a/include/linux/kasan.h b/include/linux/kasan.h
> index 2b9023224474..8654275aa62e 100644
> --- a/include/linux/kasan.h
> +++ b/include/linux/kasan.h
> @@ -2,6 +2,7 @@
> #ifndef _LINUX_KASAN_H
> #define _LINUX_KASAN_H
>
> +#include <linux/jump_label.h>
> #include <linux/types.h>
>
> struct kmem_cache;
> @@ -66,40 +67,154 @@ static inline void kasan_disable_current(void) {}
>
> #ifdef CONFIG_KASAN
>
> -void kasan_alloc_pages(struct page *page, unsigned int order);
> -void kasan_free_pages(struct page *page, unsigned int order);
> +struct kasan_cache {
> + int alloc_meta_offset;
> + int free_meta_offset;
> +};
> +
> +#ifdef CONFIG_KASAN_HW_TAGS
> +DECLARE_STATIC_KEY_FALSE(kasan_enabled);
> +#else
> +DECLARE_STATIC_KEY_TRUE(kasan_enabled);
> +#endif
>
> -void kasan_cache_create(struct kmem_cache *cache, unsigned int *size,
> - slab_flags_t *flags);
> +void __kasan_alloc_pages(struct page *page, unsigned int order);
> +static inline void kasan_alloc_pages(struct page *page, unsigned int order)
> +{
> + if (static_branch_likely(&kasan_enabled))
> + __kasan_alloc_pages(page, order);
The patch looks fine per se, but I think with the suggestion in the
previous patch, this should be:
if (kasan_is_enabled())
__kasan_alloc_pages(page, order);
No overhead for other modes and less logic duplication.
> +}
>
> -void kasan_unpoison_data(const void *address, size_t size);
> -void kasan_unpoison_slab(const void *ptr);
> +void __kasan_free_pages(struct page *page, unsigned int order);
> +static inline void kasan_free_pages(struct page *page, unsigned int order)
> +{
> + if (static_branch_likely(&kasan_enabled))
> + __kasan_free_pages(page, order);
> +}
>
> -void kasan_poison_slab(struct page *page);
> -void kasan_unpoison_object_data(struct kmem_cache *cache, void *object);
> -void kasan_poison_object_data(struct kmem_cache *cache, void *object);
> -void * __must_check kasan_init_slab_obj(struct kmem_cache *cache,
> - const void *object);
> +void __kasan_cache_create(struct kmem_cache *cache, unsigned int *size,
> + slab_flags_t *flags);
> +static inline void kasan_cache_create(struct kmem_cache *cache,
> + unsigned int *size, slab_flags_t *flags)
> +{
> + if (static_branch_likely(&kasan_enabled))
> + __kasan_cache_create(cache, size, flags);
> +}
>
> -void * __must_check kasan_kmalloc_large(const void *ptr, size_t size,
> - gfp_t flags);
> -void kasan_kfree_large(void *ptr, unsigned long ip);
> -void kasan_poison_kfree(void *ptr, unsigned long ip);
> -void * __must_check kasan_kmalloc(struct kmem_cache *s, const void *object,
> - size_t size, gfp_t flags);
> -void * __must_check kasan_krealloc(const void *object, size_t new_size,
> - gfp_t flags);
> +size_t __kasan_metadata_size(struct kmem_cache *cache);
> +static inline size_t kasan_metadata_size(struct kmem_cache *cache)
> +{
> + if (static_branch_likely(&kasan_enabled))
> + return __kasan_metadata_size(cache);
> + return 0;
> +}
>
> -void * __must_check kasan_slab_alloc(struct kmem_cache *s, void *object,
> - gfp_t flags);
> -bool kasan_slab_free(struct kmem_cache *s, void *object, unsigned long ip);
> +void __kasan_unpoison_data(const void *addr, size_t size);
> +static inline void kasan_unpoison_data(const void *addr, size_t size)
> +{
> + if (static_branch_likely(&kasan_enabled))
> + __kasan_unpoison_data(addr, size);
> +}
>
> -struct kasan_cache {
> - int alloc_meta_offset;
> - int free_meta_offset;
> -};
> +void __kasan_unpoison_slab(const void *ptr);
> +static inline void kasan_unpoison_slab(const void *ptr)
> +{
> + if (static_branch_likely(&kasan_enabled))
> + __kasan_unpoison_slab(ptr);
> +}
> +
> +void __kasan_poison_slab(struct page *page);
> +static inline void kasan_poison_slab(struct page *page)
> +{
> + if (static_branch_likely(&kasan_enabled))
> + return __kasan_poison_slab(page);
> +}
> +
> +void __kasan_unpoison_object_data(struct kmem_cache *cache, void *object);
> +static inline void kasan_unpoison_object_data(struct kmem_cache *cache, void *object)
> +{
> + if (static_branch_likely(&kasan_enabled))
> + return __kasan_unpoison_object_data(cache, object);
> +}
> +
> +void __kasan_poison_object_data(struct kmem_cache *cache, void *object);
> +static inline void kasan_poison_object_data(struct kmem_cache *cache, void *object)
> +{
> + if (static_branch_likely(&kasan_enabled))
> + __kasan_poison_object_data(cache, object);
> +}
> +
> +void * __must_check __kasan_init_slab_obj(struct kmem_cache *cache,
> + const void *object);
> +static inline void * __must_check kasan_init_slab_obj(struct kmem_cache *cache,
> + const void *object)
> +{
> + if (static_branch_likely(&kasan_enabled))
> + return __kasan_init_slab_obj(cache, object);
> + return (void *)object;
> +}
> +
> +bool __kasan_slab_free(struct kmem_cache *s, void *object, unsigned long ip);
> +static inline bool kasan_slab_free(struct kmem_cache *s, void *object, unsigned long ip)
> +{
> + if (static_branch_likely(&kasan_enabled))
> + return __kasan_slab_free(s, object, ip);
> + return false;
> +}
>
> -size_t kasan_metadata_size(struct kmem_cache *cache);
> +void * __must_check __kasan_slab_alloc(struct kmem_cache *s,
> + void *object, gfp_t flags);
> +static inline void * __must_check kasan_slab_alloc(struct kmem_cache *s,
> + void *object, gfp_t flags)
> +{
> + if (static_branch_likely(&kasan_enabled))
> + return __kasan_slab_alloc(s, object, flags);
> + return object;
> +}
> +
> +void * __must_check __kasan_kmalloc(struct kmem_cache *s, const void *object,
> + size_t size, gfp_t flags);
> +static inline void * __must_check kasan_kmalloc(struct kmem_cache *s, const void *object,
> + size_t size, gfp_t flags)
> +{
> + if (static_branch_likely(&kasan_enabled))
> + return __kasan_kmalloc(s, object, size, flags);
> + return (void *)object;
> +}
> +
> +void * __must_check __kasan_kmalloc_large(const void *ptr,
> + size_t size, gfp_t flags);
> +static inline void * __must_check kasan_kmalloc_large(const void *ptr,
> + size_t size, gfp_t flags)
> +{
> + if (static_branch_likely(&kasan_enabled))
> + return __kasan_kmalloc_large(ptr, size, flags);
> + return (void *)ptr;
> +}
> +
> +void * __must_check __kasan_krealloc(const void *object,
> + size_t new_size, gfp_t flags);
> +static inline void * __must_check kasan_krealloc(const void *object,
> + size_t new_size, gfp_t flags)
> +{
> + if (static_branch_likely(&kasan_enabled))
> + return __kasan_krealloc(object, new_size, flags);
> + return (void *)object;
> +}
> +
> +void __kasan_poison_kfree(void *ptr, unsigned long ip);
> +static inline void kasan_poison_kfree(void *ptr, unsigned long ip)
> +{
> + if (static_branch_likely(&kasan_enabled))
> + __kasan_poison_kfree(ptr, ip);
> +}
> +
> +void __kasan_kfree_large(void *ptr, unsigned long ip);
> +static inline void kasan_kfree_large(void *ptr, unsigned long ip)
> +{
> + if (static_branch_likely(&kasan_enabled))
> + __kasan_kfree_large(ptr, ip);
> +}
>
> bool kasan_save_enable_multi_shot(void);
> void kasan_restore_multi_shot(bool enabled);
> @@ -108,14 +223,12 @@ void kasan_restore_multi_shot(bool enabled);
>
> static inline void kasan_alloc_pages(struct page *page, unsigned int order) {}
> static inline void kasan_free_pages(struct page *page, unsigned int order) {}
> -
> static inline void kasan_cache_create(struct kmem_cache *cache,
> unsigned int *size,
> slab_flags_t *flags) {}
> -
> -static inline void kasan_unpoison_data(const void *address, size_t size) { }
> -static inline void kasan_unpoison_slab(const void *ptr) { }
> -
> +static inline size_t kasan_metadata_size(struct kmem_cache *cache) { return 0; }
> +static inline void kasan_unpoison_data(const void *address, size_t size) {}
> +static inline void kasan_unpoison_slab(const void *ptr) {}
> static inline void kasan_poison_slab(struct page *page) {}
> static inline void kasan_unpoison_object_data(struct kmem_cache *cache,
> void *object) {}
> @@ -126,36 +239,33 @@ static inline void *kasan_init_slab_obj(struct kmem_cache *cache,
> {
> return (void *)object;
> }
> -
> -static inline void *kasan_kmalloc_large(void *ptr, size_t size, gfp_t flags)
> +static inline bool kasan_slab_free(struct kmem_cache *s, void *object,
> + unsigned long ip)
> {
> - return ptr;
> + return false;
> }
> -static inline void kasan_kfree_large(void *ptr, unsigned long ip) {}
> -static inline void kasan_poison_kfree(void *ptr, unsigned long ip) {}
> -static inline void *kasan_kmalloc(struct kmem_cache *s, const void *object,
> - size_t size, gfp_t flags)
> +static inline void *kasan_slab_alloc(struct kmem_cache *s, void *object,
> + gfp_t flags)
> {
> - return (void *)object;
> + return object;
> }
> -static inline void *kasan_krealloc(const void *object, size_t new_size,
> - gfp_t flags)
> +static inline void *kasan_kmalloc(struct kmem_cache *s, const void *object,
> + size_t size, gfp_t flags)
> {
> return (void *)object;
> }
>
> -static inline void *kasan_slab_alloc(struct kmem_cache *s, void *object,
> - gfp_t flags)
> +static inline void *kasan_kmalloc_large(const void *ptr, size_t size, gfp_t flags)
> {
> - return object;
> + return (void *)ptr;
> }
> -static inline bool kasan_slab_free(struct kmem_cache *s, void *object,
> - unsigned long ip)
> +static inline void *kasan_krealloc(const void *object, size_t new_size,
> + gfp_t flags)
> {
> - return false;
> + return (void *)object;
> }
> -
> -static inline size_t kasan_metadata_size(struct kmem_cache *cache) { return 0; }
> +static inline void kasan_poison_kfree(void *ptr, unsigned long ip) {}
> +static inline void kasan_kfree_large(void *ptr, unsigned long ip) {}
>
> #endif /* CONFIG_KASAN */
>
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index a3cac68c737c..701e9d7666d6 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -1412,22 +1412,36 @@ static inline bool cpupid_match_pid(struct task_struct *task, int cpupid)
> #endif /* CONFIG_NUMA_BALANCING */
>
> #if defined(CONFIG_KASAN_SW_TAGS) || defined(CONFIG_KASAN_HW_TAGS)
> +
> +#ifdef CONFIG_KASAN_HW_TAGS
> +DECLARE_STATIC_KEY_FALSE(kasan_enabled);
> +#else
> +DECLARE_STATIC_KEY_TRUE(kasan_enabled);
> +#endif
> +
> static inline u8 page_kasan_tag(const struct page *page)
> {
> - return (page->flags >> KASAN_TAG_PGSHIFT) & KASAN_TAG_MASK;
> + if (static_branch_likely(&kasan_enabled))
> + return (page->flags >> KASAN_TAG_PGSHIFT) & KASAN_TAG_MASK;
> + return 0xff;
> }
>
> static inline void page_kasan_tag_set(struct page *page, u8 tag)
> {
> - page->flags &= ~(KASAN_TAG_MASK << KASAN_TAG_PGSHIFT);
> - page->flags |= (tag & KASAN_TAG_MASK) << KASAN_TAG_PGSHIFT;
> + if (static_branch_likely(&kasan_enabled)) {
> + page->flags &= ~(KASAN_TAG_MASK << KASAN_TAG_PGSHIFT);
> + page->flags |= (tag & KASAN_TAG_MASK) << KASAN_TAG_PGSHIFT;
> + }
> }
>
> static inline void page_kasan_tag_reset(struct page *page)
> {
> - page_kasan_tag_set(page, 0xff);
> + if (static_branch_likely(&kasan_enabled))
> + page_kasan_tag_set(page, 0xff);
> }
> -#else
> +
> +#else /* CONFIG_KASAN_SW_TAGS || CONFIG_KASAN_HW_TAGS */
> +
> static inline u8 page_kasan_tag(const struct page *page)
> {
> return 0xff;
> @@ -1435,7 +1449,8 @@ static inline u8 page_kasan_tag(const struct page *page)
>
> static inline void page_kasan_tag_set(struct page *page, u8 tag) { }
> static inline void page_kasan_tag_reset(struct page *page) { }
> -#endif
> +
> +#endif /* CONFIG_KASAN_SW_TAGS || CONFIG_KASAN_HW_TAGS */
>
> static inline struct zone *page_zone(const struct page *page)
> {
> diff --git a/mm/kasan/common.c b/mm/kasan/common.c
> index cc129ef62ab1..c5ec60e1a4d2 100644
> --- a/mm/kasan/common.c
> +++ b/mm/kasan/common.c
> @@ -81,7 +81,7 @@ asmlinkage void kasan_unpoison_task_stack_below(const void *watermark)
> }
> #endif /* CONFIG_KASAN_STACK */
>
> -void kasan_alloc_pages(struct page *page, unsigned int order)
> +void __kasan_alloc_pages(struct page *page, unsigned int order)
> {
> u8 tag;
> unsigned long i;
> @@ -95,7 +95,7 @@ void kasan_alloc_pages(struct page *page, unsigned int order)
> kasan_unpoison_memory(page_address(page), PAGE_SIZE << order);
> }
>
> -void kasan_free_pages(struct page *page, unsigned int order)
> +void __kasan_free_pages(struct page *page, unsigned int order)
> {
> if (likely(!PageHighMem(page)))
> kasan_poison_memory(page_address(page),
> @@ -122,8 +122,8 @@ static inline unsigned int optimal_redzone(unsigned int object_size)
> object_size <= (1 << 16) - 1024 ? 1024 : 2048;
> }
>
> -void kasan_cache_create(struct kmem_cache *cache, unsigned int *size,
> - slab_flags_t *flags)
> +void __kasan_cache_create(struct kmem_cache *cache, unsigned int *size,
> + slab_flags_t *flags)
> {
> unsigned int orig_size = *size;
> unsigned int redzone_size;
> @@ -165,7 +165,7 @@ void kasan_cache_create(struct kmem_cache *cache, unsigned int *size,
> *flags |= SLAB_KASAN;
> }
>
> -size_t kasan_metadata_size(struct kmem_cache *cache)
> +size_t __kasan_metadata_size(struct kmem_cache *cache)
> {
> if (static_branch_unlikely(&kasan_stack))
> return (cache->kasan_info.alloc_meta_offset ?
> @@ -188,17 +188,17 @@ struct kasan_free_meta *kasan_get_free_meta(struct kmem_cache *cache,
> return (void *)reset_tag(object) + cache->kasan_info.free_meta_offset;
> }
>
> -void kasan_unpoison_data(const void *address, size_t size)
> +void __kasan_unpoison_data(const void *addr, size_t size)
> {
> - kasan_unpoison_memory(address, size);
> + kasan_unpoison_memory(addr, size);
> }
>
> -void kasan_unpoison_slab(const void *ptr)
> +void __kasan_unpoison_slab(const void *ptr)
> {
> kasan_unpoison_memory(ptr, __ksize(ptr));
> }
>
> -void kasan_poison_slab(struct page *page)
> +void __kasan_poison_slab(struct page *page)
> {
> unsigned long i;
>
> @@ -208,12 +208,12 @@ void kasan_poison_slab(struct page *page)
> KASAN_KMALLOC_REDZONE);
> }
>
> -void kasan_unpoison_object_data(struct kmem_cache *cache, void *object)
> +void __kasan_unpoison_object_data(struct kmem_cache *cache, void *object)
> {
> kasan_unpoison_memory(object, cache->object_size);
> }
>
> -void kasan_poison_object_data(struct kmem_cache *cache, void *object)
> +void __kasan_poison_object_data(struct kmem_cache *cache, void *object)
> {
> kasan_poison_memory(object,
> round_up(cache->object_size, KASAN_GRANULE_SIZE),
> @@ -266,7 +266,7 @@ static u8 assign_tag(struct kmem_cache *cache, const void *object,
> #endif
> }
>
> -void * __must_check kasan_init_slab_obj(struct kmem_cache *cache,
> +void * __must_check __kasan_init_slab_obj(struct kmem_cache *cache,
> const void *object)
> {
> struct kasan_alloc_meta *alloc_meta;
> @@ -285,7 +285,7 @@ void * __must_check kasan_init_slab_obj(struct kmem_cache *cache,
> return (void *)object;
> }
>
> -static bool __kasan_slab_free(struct kmem_cache *cache, void *object,
> +static bool ____kasan_slab_free(struct kmem_cache *cache, void *object,
> unsigned long ip, bool quarantine)
> {
> u8 tag;
> @@ -329,9 +329,9 @@ static bool __kasan_slab_free(struct kmem_cache *cache, void *object,
> return false;
> }
>
> -bool kasan_slab_free(struct kmem_cache *cache, void *object, unsigned long ip)
> +bool __kasan_slab_free(struct kmem_cache *cache, void *object, unsigned long ip)
> {
> - return __kasan_slab_free(cache, object, ip, true);
> + return ____kasan_slab_free(cache, object, ip, true);
> }
>
> static void set_alloc_info(struct kmem_cache *cache, void *object, gfp_t flags)
> @@ -339,7 +339,7 @@ static void set_alloc_info(struct kmem_cache *cache, void *object, gfp_t flags)
> kasan_set_track(&kasan_get_alloc_meta(cache, object)->alloc_track, flags);
> }
>
> -static void *__kasan_kmalloc(struct kmem_cache *cache, const void *object,
> +static void *____kasan_kmalloc(struct kmem_cache *cache, const void *object,
> size_t size, gfp_t flags, bool keep_tag)
> {
> unsigned long redzone_start;
> @@ -371,20 +371,20 @@ static void *__kasan_kmalloc(struct kmem_cache *cache, const void *object,
> return set_tag(object, tag);
> }
>
> -void * __must_check kasan_slab_alloc(struct kmem_cache *cache, void *object,
> - gfp_t flags)
> +void * __must_check __kasan_slab_alloc(struct kmem_cache *cache,
> + void *object, gfp_t flags)
> {
> - return __kasan_kmalloc(cache, object, cache->object_size, flags, false);
> + return ____kasan_kmalloc(cache, object, cache->object_size, flags, false);
> }
>
> -void * __must_check kasan_kmalloc(struct kmem_cache *cache, const void *object,
> - size_t size, gfp_t flags)
> +void * __must_check __kasan_kmalloc(struct kmem_cache *cache, const void *object,
> + size_t size, gfp_t flags)
> {
> - return __kasan_kmalloc(cache, object, size, flags, true);
> + return ____kasan_kmalloc(cache, object, size, flags, true);
> }
> -EXPORT_SYMBOL(kasan_kmalloc);
> +EXPORT_SYMBOL(__kasan_kmalloc);
>
> -void * __must_check kasan_kmalloc_large(const void *ptr, size_t size,
> +void * __must_check __kasan_kmalloc_large(const void *ptr, size_t size,
> gfp_t flags)
> {
> struct page *page;
> @@ -409,7 +409,7 @@ void * __must_check kasan_kmalloc_large(const void *ptr, size_t size,
> return (void *)ptr;
> }
>
> -void * __must_check kasan_krealloc(const void *object, size_t size, gfp_t flags)
> +void * __must_check __kasan_krealloc(const void *object, size_t size, gfp_t flags)
> {
> struct page *page;
>
> @@ -419,13 +419,13 @@ void * __must_check kasan_krealloc(const void *object, size_t size, gfp_t flags)
> page = virt_to_head_page(object);
>
> if (unlikely(!PageSlab(page)))
> - return kasan_kmalloc_large(object, size, flags);
> + return __kasan_kmalloc_large(object, size, flags);
> else
> - return __kasan_kmalloc(page->slab_cache, object, size,
> + return ____kasan_kmalloc(page->slab_cache, object, size,
> flags, true);
> }
>
> -void kasan_poison_kfree(void *ptr, unsigned long ip)
> +void __kasan_poison_kfree(void *ptr, unsigned long ip)
> {
> struct page *page;
>
> @@ -438,11 +438,11 @@ void kasan_poison_kfree(void *ptr, unsigned long ip)
> }
> kasan_poison_memory(ptr, page_size(page), KASAN_FREE_PAGE);
> } else {
> - __kasan_slab_free(page->slab_cache, ptr, ip, false);
> + ____kasan_slab_free(page->slab_cache, ptr, ip, false);
> }
> }
>
> -void kasan_kfree_large(void *ptr, unsigned long ip)
> +void __kasan_kfree_large(void *ptr, unsigned long ip)
> {
> if (ptr != page_address(virt_to_head_page(ptr)))
> kasan_report_invalid_free(ptr, ip);
> --
> 2.29.0.rc1.297.gfa9743e501-goog
>
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