Message-ID: <CAG_fn=Wy7fLJd46=N9U-yQAQreioEf2ny+CGNmhUVYpbWiXA1Q@mail.gmail.com>
Date:   Wed, 18 Nov 2020 16:30:15 +0100
From:   Alexander Potapenko <glider@...gle.com>
To:     Andrey Konovalov <andreyknvl@...gle.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Vincenzo Frascino <vincenzo.frascino@....com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Marco Elver <elver@...gle.com>,
        Evgenii Stepanov <eugenis@...gle.com>,
        Branislav Rankov <Branislav.Rankov@....com>,
        Kevin Brodsky <kevin.brodsky@....com>,
        kasan-dev <kasan-dev@...glegroups.com>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Linux Memory Management List <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH mm v10 05/42] kasan: rename (un)poison_shadow to (un)poison_range

On Fri, Nov 13, 2020 at 11:16 PM Andrey Konovalov <andreyknvl@...gle.com> wrote:
>
> This is a preparatory commit for the upcoming addition of a new hardware
> tag-based (MTE-based) KASAN mode.
>
> The new mode won't be using shadow memory. Rename external annotation
> kasan_unpoison_shadow() to kasan_unpoison_range(), and introduce internal
> functions (un)poison_range() (without kasan_ prefix).
>
> Co-developed-by: Marco Elver <elver@...gle.com>
> Signed-off-by: Marco Elver <elver@...gle.com>
> Signed-off-by: Andrey Konovalov <andreyknvl@...gle.com>
> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@....com>
Reviewed-by: Alexander Potapenko <glider@...gle.com>

> ---
> Change-Id: Ia359f32815242c4704e49a5f1639ca2d2f8cba69
> ---
>  include/linux/kasan.h |  6 +++---
>  kernel/fork.c         |  4 ++--
>  mm/kasan/common.c     | 49 ++++++++++++++++++++++++-------------------
>  mm/kasan/generic.c    | 23 ++++++++++----------
>  mm/kasan/kasan.h      |  3 ++-
>  mm/kasan/tags.c       |  2 +-
>  mm/slab_common.c      |  2 +-
>  7 files changed, 47 insertions(+), 42 deletions(-)
>
> diff --git a/include/linux/kasan.h b/include/linux/kasan.h
> index 26f2ab92e7ca..d237051dca58 100644
> --- a/include/linux/kasan.h
> +++ b/include/linux/kasan.h
> @@ -71,7 +71,7 @@ extern void kasan_enable_current(void);
>  /* Disable reporting bugs for current task */
>  extern void kasan_disable_current(void);
>
> -void kasan_unpoison_shadow(const void *address, size_t size);
> +void kasan_unpoison_range(const void *address, size_t size);
>
>  void kasan_unpoison_task_stack(struct task_struct *task);
>
> @@ -108,7 +108,7 @@ struct kasan_cache {
>  size_t __ksize(const void *);
>  static inline void kasan_unpoison_slab(const void *ptr)
>  {
> -       kasan_unpoison_shadow(ptr, __ksize(ptr));
> +       kasan_unpoison_range(ptr, __ksize(ptr));
>  }
>  size_t kasan_metadata_size(struct kmem_cache *cache);
>
> @@ -117,7 +117,7 @@ void kasan_restore_multi_shot(bool enabled);
>
>  #else /* CONFIG_KASAN */
>
> -static inline void kasan_unpoison_shadow(const void *address, size_t size) {}
> +static inline void kasan_unpoison_range(const void *address, size_t size) {}
>
>  static inline void kasan_unpoison_task_stack(struct task_struct *task) {}
>
> diff --git a/kernel/fork.c b/kernel/fork.c
> index 15f189bb8ec4..bee52236f09b 100644
> --- a/kernel/fork.c
> +++ b/kernel/fork.c
> @@ -225,8 +225,8 @@ static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, int node)
>                 if (!s)
>                         continue;
>
> -               /* Clear the KASAN shadow of the stack. */
> -               kasan_unpoison_shadow(s->addr, THREAD_SIZE);
> +               /* Mark stack accessible for KASAN. */
> +               kasan_unpoison_range(s->addr, THREAD_SIZE);
>
>                 /* Clear stale pointers from reused stack. */
>                 memset(s->addr, 0, THREAD_SIZE);
> diff --git a/mm/kasan/common.c b/mm/kasan/common.c
> index f5739be60edc..6adbf5891aff 100644
> --- a/mm/kasan/common.c
> +++ b/mm/kasan/common.c
> @@ -109,7 +109,7 @@ void *memcpy(void *dest, const void *src, size_t len)
>   * Poisons the shadow memory for 'size' bytes starting from 'addr'.
>   * Memory addresses should be aligned to KASAN_SHADOW_SCALE_SIZE.
>   */
> -void kasan_poison_shadow(const void *address, size_t size, u8 value)
> +void poison_range(const void *address, size_t size, u8 value)
>  {
>         void *shadow_start, *shadow_end;
>
> @@ -130,7 +130,7 @@ void kasan_poison_shadow(const void *address, size_t size, u8 value)
>         __memset(shadow_start, value, shadow_end - shadow_start);
>  }
>
> -void kasan_unpoison_shadow(const void *address, size_t size)
> +void unpoison_range(const void *address, size_t size)
>  {
>         u8 tag = get_tag(address);
>
> @@ -149,7 +149,7 @@ void kasan_unpoison_shadow(const void *address, size_t size)
>         if (is_kfence_address(address))
>                 return;
>
> -       kasan_poison_shadow(address, size, tag);
> +       poison_range(address, size, tag);
>
>         if (size & KASAN_SHADOW_MASK) {
>                 u8 *shadow = (u8 *)kasan_mem_to_shadow(address + size);
> @@ -161,12 +161,17 @@ void kasan_unpoison_shadow(const void *address, size_t size)
>         }
>  }
>
> +void kasan_unpoison_range(const void *address, size_t size)
> +{
> +       unpoison_range(address, size);
> +}
> +
>  static void __kasan_unpoison_stack(struct task_struct *task, const void *sp)
>  {
>         void *base = task_stack_page(task);
>         size_t size = sp - base;
>
> -       kasan_unpoison_shadow(base, size);
> +       unpoison_range(base, size);
>  }
>
>  /* Unpoison the entire stack for a task. */
> @@ -185,7 +190,7 @@ asmlinkage void kasan_unpoison_task_stack_below(const void *watermark)
>          */
>         void *base = (void *)((unsigned long)watermark & ~(THREAD_SIZE - 1));
>
> -       kasan_unpoison_shadow(base, watermark - base);
> +       unpoison_range(base, watermark - base);
>  }
>
>  void kasan_alloc_pages(struct page *page, unsigned int order)
> @@ -199,13 +204,13 @@ void kasan_alloc_pages(struct page *page, unsigned int order)
>         tag = random_tag();
>         for (i = 0; i < (1 << order); i++)
>                 page_kasan_tag_set(page + i, tag);
> -       kasan_unpoison_shadow(page_address(page), PAGE_SIZE << order);
> +       unpoison_range(page_address(page), PAGE_SIZE << order);
>  }
>
>  void kasan_free_pages(struct page *page, unsigned int order)
>  {
>         if (likely(!PageHighMem(page)))
> -               kasan_poison_shadow(page_address(page),
> +               poison_range(page_address(page),
>                                 PAGE_SIZE << order,
>                                 KASAN_FREE_PAGE);
>  }
> @@ -297,18 +302,18 @@ void kasan_poison_slab(struct page *page)
>
>         for (i = 0; i < compound_nr(page); i++)
>                 page_kasan_tag_reset(page + i);
> -       kasan_poison_shadow(page_address(page), page_size(page),
> -                       KASAN_KMALLOC_REDZONE);
> +       poison_range(page_address(page), page_size(page),
> +                    KASAN_KMALLOC_REDZONE);
>  }
>
>  void kasan_unpoison_object_data(struct kmem_cache *cache, void *object)
>  {
> -       kasan_unpoison_shadow(object, cache->object_size);
> +       unpoison_range(object, cache->object_size);
>  }
>
>  void kasan_poison_object_data(struct kmem_cache *cache, void *object)
>  {
> -       kasan_poison_shadow(object,
> +       poison_range(object,
>                         round_up(cache->object_size, KASAN_SHADOW_SCALE_SIZE),
>                         KASAN_KMALLOC_REDZONE);
>  }
> @@ -424,7 +429,7 @@ static bool __kasan_slab_free(struct kmem_cache *cache, void *object,
>         }
>
>         rounded_up_size = round_up(cache->object_size, KASAN_SHADOW_SCALE_SIZE);
> -       kasan_poison_shadow(object, rounded_up_size, KASAN_KMALLOC_FREE);
> +       poison_range(object, rounded_up_size, KASAN_KMALLOC_FREE);
>
>         if ((IS_ENABLED(CONFIG_KASAN_GENERIC) && !quarantine) ||
>                         unlikely(!(cache->flags & SLAB_KASAN)))
> @@ -467,9 +472,9 @@ static void *__kasan_kmalloc(struct kmem_cache *cache, const void *object,
>                 tag = assign_tag(cache, object, false, keep_tag);
>
>         /* Tag is ignored in set_tag without CONFIG_KASAN_SW_TAGS */
> -       kasan_unpoison_shadow(set_tag(object, tag), size);
> -       kasan_poison_shadow((void *)redzone_start, redzone_end - redzone_start,
> -               KASAN_KMALLOC_REDZONE);
> +       unpoison_range(set_tag(object, tag), size);
> +       poison_range((void *)redzone_start, redzone_end - redzone_start,
> +                    KASAN_KMALLOC_REDZONE);
>
>         if (cache->flags & SLAB_KASAN)
>                 kasan_set_track(&get_alloc_info(cache, object)->alloc_track, flags);
> @@ -508,9 +513,9 @@ void * __must_check kasan_kmalloc_large(const void *ptr, size_t size,
>                                 KASAN_SHADOW_SCALE_SIZE);
>         redzone_end = (unsigned long)ptr + page_size(page);
>
> -       kasan_unpoison_shadow(ptr, size);
> -       kasan_poison_shadow((void *)redzone_start, redzone_end - redzone_start,
> -               KASAN_PAGE_REDZONE);
> +       unpoison_range(ptr, size);
> +       poison_range((void *)redzone_start, redzone_end - redzone_start,
> +                    KASAN_PAGE_REDZONE);
>
>         return (void *)ptr;
>  }
> @@ -542,7 +547,7 @@ void kasan_poison_kfree(void *ptr, unsigned long ip)
>                         kasan_report_invalid_free(ptr, ip);
>                         return;
>                 }
> -               kasan_poison_shadow(ptr, page_size(page), KASAN_FREE_PAGE);
> +               poison_range(ptr, page_size(page), KASAN_FREE_PAGE);
>         } else {
>                 __kasan_slab_free(page->slab_cache, ptr, ip, false);
>         }
> @@ -728,7 +733,7 @@ int kasan_populate_vmalloc(unsigned long addr, unsigned long size)
>          * // vmalloc() allocates memory
>          * // let a = area->addr
>          * // we reach kasan_populate_vmalloc
> -        * // and call kasan_unpoison_shadow:
> +        * // and call unpoison_range:
>          * STORE shadow(a), unpoison_val
>          * ...
>          * STORE shadow(a+99), unpoison_val     x = LOAD p
> @@ -763,7 +768,7 @@ void kasan_poison_vmalloc(const void *start, unsigned long size)
>                 return;
>
>         size = round_up(size, KASAN_SHADOW_SCALE_SIZE);
> -       kasan_poison_shadow(start, size, KASAN_VMALLOC_INVALID);
> +       poison_range(start, size, KASAN_VMALLOC_INVALID);
>  }
>
>  void kasan_unpoison_vmalloc(const void *start, unsigned long size)
> @@ -771,7 +776,7 @@ void kasan_unpoison_vmalloc(const void *start, unsigned long size)
>         if (!is_vmalloc_or_module_addr(start))
>                 return;
>
> -       kasan_unpoison_shadow(start, size);
> +       unpoison_range(start, size);
>  }
>
>  static int kasan_depopulate_vmalloc_pte(pte_t *ptep, unsigned long addr,
> diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c
> index d6a386255007..cdc2d8112f3e 100644
> --- a/mm/kasan/generic.c
> +++ b/mm/kasan/generic.c
> @@ -203,11 +203,11 @@ static void register_global(struct kasan_global *global)
>  {
>         size_t aligned_size = round_up(global->size, KASAN_SHADOW_SCALE_SIZE);
>
> -       kasan_unpoison_shadow(global->beg, global->size);
> +       unpoison_range(global->beg, global->size);
>
> -       kasan_poison_shadow(global->beg + aligned_size,
> -               global->size_with_redzone - aligned_size,
> -               KASAN_GLOBAL_REDZONE);
> +       poison_range(global->beg + aligned_size,
> +                    global->size_with_redzone - aligned_size,
> +                    KASAN_GLOBAL_REDZONE);
>  }
>
>  void __asan_register_globals(struct kasan_global *globals, size_t size)
> @@ -286,13 +286,12 @@ void __asan_alloca_poison(unsigned long addr, size_t size)
>
>         WARN_ON(!IS_ALIGNED(addr, KASAN_ALLOCA_REDZONE_SIZE));
>
> -       kasan_unpoison_shadow((const void *)(addr + rounded_down_size),
> -                             size - rounded_down_size);
> -       kasan_poison_shadow(left_redzone, KASAN_ALLOCA_REDZONE_SIZE,
> -                       KASAN_ALLOCA_LEFT);
> -       kasan_poison_shadow(right_redzone,
> -                       padding_size + KASAN_ALLOCA_REDZONE_SIZE,
> -                       KASAN_ALLOCA_RIGHT);
> +       unpoison_range((const void *)(addr + rounded_down_size),
> +                      size - rounded_down_size);
> +       poison_range(left_redzone, KASAN_ALLOCA_REDZONE_SIZE,
> +                    KASAN_ALLOCA_LEFT);
> +       poison_range(right_redzone, padding_size + KASAN_ALLOCA_REDZONE_SIZE,
> +                    KASAN_ALLOCA_RIGHT);
>  }
>  EXPORT_SYMBOL(__asan_alloca_poison);
>
> @@ -302,7 +301,7 @@ void __asan_allocas_unpoison(const void *stack_top, const void *stack_bottom)
>         if (unlikely(!stack_top || stack_top > stack_bottom))
>                 return;
>
> -       kasan_unpoison_shadow(stack_top, stack_bottom - stack_top);
> +       unpoison_range(stack_top, stack_bottom - stack_top);
>  }
>  EXPORT_SYMBOL(__asan_allocas_unpoison);
>
> diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
> index ac499456740f..42ab02c61331 100644
> --- a/mm/kasan/kasan.h
> +++ b/mm/kasan/kasan.h
> @@ -150,7 +150,8 @@ static inline bool addr_has_shadow(const void *addr)
>         return (addr >= kasan_shadow_to_mem((void *)KASAN_SHADOW_START));
>  }
>
> -void kasan_poison_shadow(const void *address, size_t size, u8 value);
> +void poison_range(const void *address, size_t size, u8 value);
> +void unpoison_range(const void *address, size_t size);
>
>  /**
>   * check_memory_region - Check memory region, and report if invalid access.
> diff --git a/mm/kasan/tags.c b/mm/kasan/tags.c
> index 5c8b08a25715..c0b3f327812b 100644
> --- a/mm/kasan/tags.c
> +++ b/mm/kasan/tags.c
> @@ -153,7 +153,7 @@ EXPORT_SYMBOL(__hwasan_storeN_noabort);
>
>  void __hwasan_tag_memory(unsigned long addr, u8 tag, unsigned long size)
>  {
> -       kasan_poison_shadow((void *)addr, size, tag);
> +       poison_range((void *)addr, size, tag);
>  }
>  EXPORT_SYMBOL(__hwasan_tag_memory);
>
> diff --git a/mm/slab_common.c b/mm/slab_common.c
> index 479d17b90155..0b5ae1819a8b 100644
> --- a/mm/slab_common.c
> +++ b/mm/slab_common.c
> @@ -1179,7 +1179,7 @@ size_t ksize(const void *objp)
>          * We assume that ksize callers could use whole allocated area,
>          * so we need to unpoison this area.
>          */
> -       kasan_unpoison_shadow(objp, size);
> +       kasan_unpoison_range(objp, size);
>         return size;
>  }
>  EXPORT_SYMBOL(ksize);
> --
> 2.29.2.299.gdc1121823c-goog
>


-- 
Alexander Potapenko
Software Engineer

Google Germany GmbH
Erika-Mann-Straße, 33
80636 München

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