Re: [PATCH mm v3 12/19] kasan, mm: check kasan_enabled in annotations

[Dmitry Vyukov]

On Mon, Nov 16, 2020 at 4:26 PM Marco Elver <elver@xxxxxxxxxx> wrote:
>
> On Fri, Nov 13, 2020 at 11:20PM +0100, Andrey Konovalov 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.
> >
> > Co-developed-by: Vincenzo Frascino <Vincenzo.Frascino@xxxxxxx>
> > Signed-off-by: Vincenzo Frascino <Vincenzo.Frascino@xxxxxxx>
> > Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
> > Link: https://linux-review.googlesource.com/id/I2589451d3c96c97abbcbf714baabe6161c6f153e
>
> Reviewed-by: Marco Elver <elver@xxxxxxxxxx>

Also much nicer with kasan_enabled() now.

Reviewed-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>

> > ---
> >  include/linux/kasan.h | 213 ++++++++++++++++++++++++++++++++----------
> >  include/linux/mm.h    |  22 +++--
> >  mm/kasan/common.c     |  56 +++++------
> >  3 files changed, 210 insertions(+), 81 deletions(-)
> >
> > diff --git a/include/linux/kasan.h b/include/linux/kasan.h
> > index 872bf145ddde..6bd95243a583 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/static_key.h>
> >  #include <linux/types.h>
> >
> >  struct kmem_cache;
> > @@ -74,54 +75,176 @@ static inline void kasan_disable_current(void) {}
> >
> >  #ifdef CONFIG_KASAN
> >
> > -void kasan_unpoison_range(const void *address, size_t size);
> > +struct kasan_cache {
> > +     int alloc_meta_offset;
> > +     int free_meta_offset;
> > +};
> >
> > -void kasan_alloc_pages(struct page *page, unsigned int order);
> > -void kasan_free_pages(struct page *page, unsigned int order);
> > +#ifdef CONFIG_KASAN_HW_TAGS
> > +DECLARE_STATIC_KEY_FALSE(kasan_flag_enabled);
> > +static __always_inline bool kasan_enabled(void)
> > +{
> > +     return static_branch_likely(&kasan_flag_enabled);
> > +}
> > +#else
> > +static inline bool kasan_enabled(void)
> > +{
> > +     return true;
> > +}
> > +#endif
> >
> > -void kasan_cache_create(struct kmem_cache *cache, unsigned int *size,
> > -                     slab_flags_t *flags);
> > +void __kasan_unpoison_range(const void *addr, size_t size);
> > +static __always_inline void kasan_unpoison_range(const void *addr, size_t size)
> > +{
> > +     if (kasan_enabled())
> > +             __kasan_unpoison_range(addr, size);
> > +}
> >
> > -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_alloc_pages(struct page *page, unsigned int order);
> > +static __always_inline void kasan_alloc_pages(struct page *page,
> > +                                             unsigned int order)
> > +{
> > +     if (kasan_enabled())
> > +             __kasan_alloc_pages(page, order);
> > +}
> >
> > -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);
> > +void __kasan_free_pages(struct page *page, unsigned int order);
> > +static __always_inline void kasan_free_pages(struct page *page,
> > +                                             unsigned int order)
> > +{
> > +     if (kasan_enabled())
> > +             __kasan_free_pages(page, order);
> > +}
> >
> > -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_cache_create(struct kmem_cache *cache, unsigned int *size,
> > +                             slab_flags_t *flags);
> > +static __always_inline void kasan_cache_create(struct kmem_cache *cache,
> > +                             unsigned int *size, slab_flags_t *flags)
> > +{
> > +     if (kasan_enabled())
> > +             __kasan_cache_create(cache, size, flags);
> > +}
> >
> > -struct kasan_cache {
> > -     int alloc_meta_offset;
> > -     int free_meta_offset;
> > -};
> > +size_t __kasan_metadata_size(struct kmem_cache *cache);
> > +static __always_inline size_t kasan_metadata_size(struct kmem_cache *cache)
> > +{
> > +     if (kasan_enabled())
> > +             return __kasan_metadata_size(cache);
> > +     return 0;
> > +}
> > +
> > +void __kasan_poison_slab(struct page *page);
> > +static __always_inline void kasan_poison_slab(struct page *page)
> > +{
> > +     if (kasan_enabled())
> > +             return __kasan_poison_slab(page);
> > +}
> > +
> > +void __kasan_unpoison_object_data(struct kmem_cache *cache, void *object);
> > +static __always_inline void kasan_unpoison_object_data(struct kmem_cache *cache,
> > +                                                     void *object)
> > +{
> > +     if (kasan_enabled())
> > +             return __kasan_unpoison_object_data(cache, object);
> > +}
> > +
> > +void __kasan_poison_object_data(struct kmem_cache *cache, void *object);
> > +static __always_inline void kasan_poison_object_data(struct kmem_cache *cache,
> > +                                                     void *object)
> > +{
> > +     if (kasan_enabled())
> > +             __kasan_poison_object_data(cache, object);
> > +}
> > +
> > +void * __must_check __kasan_init_slab_obj(struct kmem_cache *cache,
> > +                                       const void *object);
> > +static __always_inline void * __must_check kasan_init_slab_obj(
> > +                             struct kmem_cache *cache, const void *object)
> > +{
> > +     if (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 __always_inline bool kasan_slab_free(struct kmem_cache *s, void *object,
> > +                                             unsigned long ip)
> > +{
> > +     if (kasan_enabled())
> > +             return __kasan_slab_free(s, object, ip);
> > +     return false;
> > +}
> > +
> > +void * __must_check __kasan_slab_alloc(struct kmem_cache *s,
> > +                                    void *object, gfp_t flags);
> > +static __always_inline void * __must_check kasan_slab_alloc(
> > +                             struct kmem_cache *s, void *object, gfp_t flags)
> > +{
> > +     if (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 __always_inline void * __must_check kasan_kmalloc(struct kmem_cache *s,
> > +                             const void *object, size_t size, gfp_t flags)
> > +{
> > +     if (kasan_enabled())
> > +             return __kasan_kmalloc(s, object, size, flags);
> > +     return (void *)object;
> > +}
> >
> > -size_t kasan_metadata_size(struct kmem_cache *cache);
> > +void * __must_check __kasan_kmalloc_large(const void *ptr,
> > +                                       size_t size, gfp_t flags);
> > +static __always_inline void * __must_check kasan_kmalloc_large(const void *ptr,
> > +                                                   size_t size, gfp_t flags)
> > +{
> > +     if (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 __always_inline void * __must_check kasan_krealloc(const void *object,
> > +                                              size_t new_size, gfp_t flags)
> > +{
> > +     if (kasan_enabled())
> > +             return __kasan_krealloc(object, new_size, flags);
> > +     return (void *)object;
> > +}
> > +
> > +void __kasan_poison_kfree(void *ptr, unsigned long ip);
> > +static __always_inline void kasan_poison_kfree(void *ptr, unsigned long ip)
> > +{
> > +     if (kasan_enabled())
> > +             __kasan_poison_kfree(ptr, ip);
> > +}
> > +
> > +void __kasan_kfree_large(void *ptr, unsigned long ip);
> > +static __always_inline void kasan_kfree_large(void *ptr, unsigned long ip)
> > +{
> > +     if (kasan_enabled())
> > +             __kasan_kfree_large(ptr, ip);
> > +}
> >
> >  bool kasan_save_enable_multi_shot(void);
> >  void kasan_restore_multi_shot(bool enabled);
> >
> >  #else /* CONFIG_KASAN */
> >
> > +static inline bool kasan_enabled(void)
> > +{
> > +     return false;
> > +}
> >  static inline void kasan_unpoison_range(const void *address, size_t size) {}
> > -
> >  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 size_t kasan_metadata_size(struct kmem_cache *cache) { return 0; }
> >  static inline void kasan_poison_slab(struct page *page) {}
> >  static inline void kasan_unpoison_object_data(struct kmem_cache *cache,
> >                                       void *object) {}
> > @@ -132,36 +255,32 @@ 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_slab_alloc(struct kmem_cache *s, void *object,
> > +                                gfp_t flags)
> > +{
> > +     return object;
> >  }
> > -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)
> >  {
> >       return (void *)object;
> >  }
> > +static inline void *kasan_kmalloc_large(const void *ptr, size_t size, gfp_t flags)
> > +{
> > +     return (void *)ptr;
> > +}
> >  static inline void *kasan_krealloc(const void *object, size_t new_size,
> >                                gfp_t flags)
> >  {
> >       return (void *)object;
> >  }
> > -
> > -static inline void *kasan_slab_alloc(struct kmem_cache *s, void *object,
> > -                                gfp_t flags)
> > -{
> > -     return object;
> > -}
> > -static inline bool kasan_slab_free(struct kmem_cache *s, void *object,
> > -                                unsigned long ip)
> > -{
> > -     return false;
> > -}
> > -
> > -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 947f4f1a6536..24f47e140a4c 100644
> > --- a/include/linux/mm.h
> > +++ b/include/linux/mm.h
> > @@ -31,6 +31,7 @@
> >  #include <linux/sizes.h>
> >  #include <linux/sched.h>
> >  #include <linux/pgtable.h>
> > +#include <linux/kasan.h>
> >
> >  struct mempolicy;
> >  struct anon_vma;
> > @@ -1415,22 +1416,30 @@ 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)
> > +
> >  static inline u8 page_kasan_tag(const struct page *page)
> >  {
> > -     return (page->flags >> KASAN_TAG_PGSHIFT) & KASAN_TAG_MASK;
> > +     if (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 (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 (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;
> > @@ -1438,7 +1447,8 @@ 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 a11e3e75eb08..17918bd20ed9 100644
> > --- a/mm/kasan/common.c
> > +++ b/mm/kasan/common.c
> > @@ -59,7 +59,7 @@ void kasan_disable_current(void)
> >  }
> >  #endif /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS */
> >
> > -void kasan_unpoison_range(const void *address, size_t size)
> > +void __kasan_unpoison_range(const void *address, size_t size)
> >  {
> >       unpoison_range(address, size);
> >  }
> > @@ -87,7 +87,7 @@ 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;
> > @@ -101,7 +101,7 @@ void kasan_alloc_pages(struct page *page, unsigned int order)
> >       unpoison_range(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)))
> >               poison_range(page_address(page),
> > @@ -128,8 +128,8 @@ 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;
> > @@ -174,7 +174,7 @@ 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 (!kasan_stack_collection_enabled())
> >               return 0;
> > @@ -197,7 +197,7 @@ struct kasan_free_meta *kasan_get_free_meta(struct kmem_cache *cache,
> >       return kasan_reset_tag(object) + cache->kasan_info.free_meta_offset;
> >  }
> >
> > -void kasan_poison_slab(struct page *page)
> > +void __kasan_poison_slab(struct page *page)
> >  {
> >       unsigned long i;
> >
> > @@ -207,12 +207,12 @@ 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)
> >  {
> >       unpoison_range(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)
> >  {
> >       poison_range(object,
> >                       round_up(cache->object_size, KASAN_GRANULE_SIZE),
> > @@ -265,7 +265,7 @@ 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;
> > @@ -284,7 +284,7 @@ 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;
> > @@ -330,9 +330,9 @@ static bool __kasan_slab_free(struct kmem_cache *cache, void *object,
> >       return IS_ENABLED(CONFIG_KASAN_GENERIC);
> >  }
> >
> > -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)
> > @@ -340,7 +340,7 @@ 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;
> > @@ -375,20 +375,20 @@ 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;
> > @@ -413,7 +413,7 @@ 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;
> >
> > @@ -423,13 +423,13 @@ 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;
> >
> > @@ -442,11 +442,11 @@ void kasan_poison_kfree(void *ptr, unsigned long ip)
> >               }
> >               poison_range(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);
> > --
> > 2.29.2.299.gdc1121823c-goog
> >