Re: [PATCH v4 2/3] kasan: integrate the common part of two KASAN tag-based modes

From: Marco Elver <elver@google.com>
To: Kuan-Ying Lee <Kuan-Ying.Lee@mediatek.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>,
	Alexander Potapenko <glider@google.com>,
	Andrey Konovalov <andreyknvl@gmail.com>,
	Dmitry Vyukov <dvyukov@google.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Matthias Brugger <matthias.bgg@gmail.com>,
	kasan-dev@googlegroups.com, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org,
	linux-mediatek@lists.infradead.org, wsd_upstream@mediatek.com,
	chinwen.chang@mediatek.com, nicholas.tang@mediatek.com
Subject: Re: [PATCH v4 2/3] kasan: integrate the common part of two KASAN tag-based modes
Date: Mon, 28 Jun 2021 08:00:00 +0200	[thread overview]
Message-ID: <CANpmjNO6odUDsERDtw2Qrt9VOTXXfswtcFw06fiRoAUvqKaK2w@mail.gmail.com> (raw)
In-Reply-To: <20210626100931.22794-3-Kuan-Ying.Lee@mediatek.com>

On Sat, 26 Jun 2021 at 12:09, Kuan-Ying Lee <Kuan-Ying.Lee@mediatek.com> wrote:
>
> 1. Move kasan_get_free_track() and kasan_set_free_info()
>    into tags.c and combine these two functions for
>    SW_TAGS and HW_TAGS kasan mode.
> 2. Move kasan_get_bug_type() to report_tags.c and
>    make this function compatible for SW_TAGS and
>    HW_TAGS kasan mode.
>
> Signed-off-by: Kuan-Ying Lee <Kuan-Ying.Lee@mediatek.com>
> Suggested-by: Marco Elver <elver@google.com>
> Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
> Cc: Alexander Potapenko <glider@google.com>
> Cc: Andrey Konovalov <andreyknvl@gmail.com>
> Cc: Dmitry Vyukov <dvyukov@google.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>

Reviewed-by: Marco Elver <elver@google.com>


> ---
>  mm/kasan/Makefile         |  4 +--
>  mm/kasan/hw_tags.c        | 22 ---------------
>  mm/kasan/report_hw_tags.c |  5 ----
>  mm/kasan/report_sw_tags.c | 43 ----------------------------
>  mm/kasan/report_tags.c    | 51 +++++++++++++++++++++++++++++++++
>  mm/kasan/sw_tags.c        | 41 ---------------------------
>  mm/kasan/tags.c           | 59 +++++++++++++++++++++++++++++++++++++++
>  7 files changed, 112 insertions(+), 113 deletions(-)
>  create mode 100644 mm/kasan/report_tags.c
>  create mode 100644 mm/kasan/tags.c
>
> diff --git a/mm/kasan/Makefile b/mm/kasan/Makefile
> index 9fe39a66388a..adcd9acaef61 100644
> --- a/mm/kasan/Makefile
> +++ b/mm/kasan/Makefile
> @@ -37,5 +37,5 @@ CFLAGS_sw_tags.o := $(CC_FLAGS_KASAN_RUNTIME)
>
>  obj-$(CONFIG_KASAN) := common.o report.o
>  obj-$(CONFIG_KASAN_GENERIC) += init.o generic.o report_generic.o shadow.o quarantine.o
> -obj-$(CONFIG_KASAN_HW_TAGS) += hw_tags.o report_hw_tags.o
> -obj-$(CONFIG_KASAN_SW_TAGS) += init.o report_sw_tags.o shadow.o sw_tags.o
> +obj-$(CONFIG_KASAN_HW_TAGS) += hw_tags.o report_hw_tags.o tags.o report_tags.o
> +obj-$(CONFIG_KASAN_SW_TAGS) += init.o report_sw_tags.o shadow.o sw_tags.o tags.o report_tags.o
> diff --git a/mm/kasan/hw_tags.c b/mm/kasan/hw_tags.c
> index ed5e5b833d61..4ea8c368b5b8 100644
> --- a/mm/kasan/hw_tags.c
> +++ b/mm/kasan/hw_tags.c
> @@ -216,28 +216,6 @@ void __init kasan_init_hw_tags(void)
>         pr_info("KernelAddressSanitizer initialized\n");
>  }
>
> -void kasan_set_free_info(struct kmem_cache *cache,
> -                               void *object, u8 tag)
> -{
> -       struct kasan_alloc_meta *alloc_meta;
> -
> -       alloc_meta = kasan_get_alloc_meta(cache, object);
> -       if (alloc_meta)
> -               kasan_set_track(&alloc_meta->free_track[0], GFP_NOWAIT);
> -}
> -
> -struct kasan_track *kasan_get_free_track(struct kmem_cache *cache,
> -                               void *object, u8 tag)
> -{
> -       struct kasan_alloc_meta *alloc_meta;
> -
> -       alloc_meta = kasan_get_alloc_meta(cache, object);
> -       if (!alloc_meta)
> -               return NULL;
> -
> -       return &alloc_meta->free_track[0];
> -}
> -
>  void kasan_alloc_pages(struct page *page, unsigned int order, gfp_t flags)
>  {
>         /*
> diff --git a/mm/kasan/report_hw_tags.c b/mm/kasan/report_hw_tags.c
> index 42b2168755d6..5dbbbb930e7a 100644
> --- a/mm/kasan/report_hw_tags.c
> +++ b/mm/kasan/report_hw_tags.c
> @@ -15,11 +15,6 @@
>
>  #include "kasan.h"
>
> -const char *kasan_get_bug_type(struct kasan_access_info *info)
> -{
> -       return "invalid-access";
> -}
> -
>  void *kasan_find_first_bad_addr(void *addr, size_t size)
>  {
>         return kasan_reset_tag(addr);
> diff --git a/mm/kasan/report_sw_tags.c b/mm/kasan/report_sw_tags.c
> index 821a14a19a92..d2298c357834 100644
> --- a/mm/kasan/report_sw_tags.c
> +++ b/mm/kasan/report_sw_tags.c
> @@ -29,49 +29,6 @@
>  #include "kasan.h"
>  #include "../slab.h"
>
> -const char *kasan_get_bug_type(struct kasan_access_info *info)
> -{
> -#ifdef CONFIG_KASAN_TAGS_IDENTIFY
> -       struct kasan_alloc_meta *alloc_meta;
> -       struct kmem_cache *cache;
> -       struct page *page;
> -       const void *addr;
> -       void *object;
> -       u8 tag;
> -       int i;
> -
> -       tag = get_tag(info->access_addr);
> -       addr = kasan_reset_tag(info->access_addr);
> -       page = kasan_addr_to_page(addr);
> -       if (page && PageSlab(page)) {
> -               cache = page->slab_cache;
> -               object = nearest_obj(cache, page, (void *)addr);
> -               alloc_meta = kasan_get_alloc_meta(cache, object);
> -
> -               if (alloc_meta) {
> -                       for (i = 0; i < KASAN_NR_FREE_STACKS; i++) {
> -                               if (alloc_meta->free_pointer_tag[i] == tag)
> -                                       return "use-after-free";
> -                       }
> -               }
> -               return "out-of-bounds";
> -       }
> -
> -#endif
> -       /*
> -        * If access_size is a negative number, then it has reason to be
> -        * defined as out-of-bounds bug type.
> -        *
> -        * Casting negative numbers to size_t would indeed turn up as
> -        * a large size_t and its value will be larger than ULONG_MAX/2,
> -        * so that this can qualify as out-of-bounds.
> -        */
> -       if (info->access_addr + info->access_size < info->access_addr)
> -               return "out-of-bounds";
> -
> -       return "invalid-access";
> -}
> -
>  void *kasan_find_first_bad_addr(void *addr, size_t size)
>  {
>         u8 tag = get_tag(addr);
> diff --git a/mm/kasan/report_tags.c b/mm/kasan/report_tags.c
> new file mode 100644
> index 000000000000..8a319fc16dab
> --- /dev/null
> +++ b/mm/kasan/report_tags.c
> @@ -0,0 +1,51 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (c) 2014 Samsung Electronics Co., Ltd.
> + * Copyright (c) 2020 Google, Inc.
> + */
> +
> +#include "kasan.h"
> +#include "../slab.h"
> +
> +const char *kasan_get_bug_type(struct kasan_access_info *info)
> +{
> +#ifdef CONFIG_KASAN_TAGS_IDENTIFY
> +       struct kasan_alloc_meta *alloc_meta;
> +       struct kmem_cache *cache;
> +       struct page *page;
> +       const void *addr;
> +       void *object;
> +       u8 tag;
> +       int i;
> +
> +       tag = get_tag(info->access_addr);
> +       addr = kasan_reset_tag(info->access_addr);
> +       page = kasan_addr_to_page(addr);
> +       if (page && PageSlab(page)) {
> +               cache = page->slab_cache;
> +               object = nearest_obj(cache, page, (void *)addr);
> +               alloc_meta = kasan_get_alloc_meta(cache, object);
> +
> +               if (alloc_meta) {
> +                       for (i = 0; i < KASAN_NR_FREE_STACKS; i++) {
> +                               if (alloc_meta->free_pointer_tag[i] == tag)
> +                                       return "use-after-free";
> +                       }
> +               }
> +               return "out-of-bounds";
> +       }
> +#endif
> +
> +       /*
> +        * If access_size is a negative number, then it has reason to be
> +        * defined as out-of-bounds bug type.
> +        *
> +        * Casting negative numbers to size_t would indeed turn up as
> +        * a large size_t and its value will be larger than ULONG_MAX/2,
> +        * so that this can qualify as out-of-bounds.
> +        */
> +       if (info->access_addr + info->access_size < info->access_addr)
> +               return "out-of-bounds";
> +
> +       return "invalid-access";
> +}
> diff --git a/mm/kasan/sw_tags.c b/mm/kasan/sw_tags.c
> index dd05e6c801fa..bd3f540feb47 100644
> --- a/mm/kasan/sw_tags.c
> +++ b/mm/kasan/sw_tags.c
> @@ -167,47 +167,6 @@ void __hwasan_tag_memory(unsigned long addr, u8 tag, unsigned long size)
>  }
>  EXPORT_SYMBOL(__hwasan_tag_memory);
>
> -void kasan_set_free_info(struct kmem_cache *cache,
> -                               void *object, u8 tag)
> -{
> -       struct kasan_alloc_meta *alloc_meta;
> -       u8 idx = 0;
> -
> -       alloc_meta = kasan_get_alloc_meta(cache, object);
> -       if (!alloc_meta)
> -               return;
> -
> -#ifdef CONFIG_KASAN_TAGS_IDENTIFY
> -       idx = alloc_meta->free_track_idx;
> -       alloc_meta->free_pointer_tag[idx] = tag;
> -       alloc_meta->free_track_idx = (idx + 1) % KASAN_NR_FREE_STACKS;
> -#endif
> -
> -       kasan_set_track(&alloc_meta->free_track[idx], GFP_NOWAIT);
> -}
> -
> -struct kasan_track *kasan_get_free_track(struct kmem_cache *cache,
> -                               void *object, u8 tag)
> -{
> -       struct kasan_alloc_meta *alloc_meta;
> -       int i = 0;
> -
> -       alloc_meta = kasan_get_alloc_meta(cache, object);
> -       if (!alloc_meta)
> -               return NULL;
> -
> -#ifdef CONFIG_KASAN_TAGS_IDENTIFY
> -       for (i = 0; i < KASAN_NR_FREE_STACKS; i++) {
> -               if (alloc_meta->free_pointer_tag[i] == tag)
> -                       break;
> -       }
> -       if (i == KASAN_NR_FREE_STACKS)
> -               i = alloc_meta->free_track_idx;
> -#endif
> -
> -       return &alloc_meta->free_track[i];
> -}
> -
>  void kasan_tag_mismatch(unsigned long addr, unsigned long access_info,
>                         unsigned long ret_ip)
>  {
> diff --git a/mm/kasan/tags.c b/mm/kasan/tags.c
> new file mode 100644
> index 000000000000..8f48b9502a17
> --- /dev/null
> +++ b/mm/kasan/tags.c
> @@ -0,0 +1,59 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * This file contains common tag-based KASAN code.
> + *
> + * Copyright (c) 2018 Google, Inc.
> + * Copyright (c) 2020 Google, Inc.
> + */
> +
> +#include <linux/init.h>
> +#include <linux/kasan.h>
> +#include <linux/kernel.h>
> +#include <linux/memory.h>
> +#include <linux/mm.h>
> +#include <linux/static_key.h>
> +#include <linux/string.h>
> +#include <linux/types.h>
> +
> +#include "kasan.h"
> +
> +void kasan_set_free_info(struct kmem_cache *cache,
> +                               void *object, u8 tag)
> +{
> +       struct kasan_alloc_meta *alloc_meta;
> +       u8 idx = 0;
> +
> +       alloc_meta = kasan_get_alloc_meta(cache, object);
> +       if (!alloc_meta)
> +               return;
> +
> +#ifdef CONFIG_KASAN_TAGS_IDENTIFY
> +       idx = alloc_meta->free_track_idx;
> +       alloc_meta->free_pointer_tag[idx] = tag;
> +       alloc_meta->free_track_idx = (idx + 1) % KASAN_NR_FREE_STACKS;
> +#endif
> +
> +       kasan_set_track(&alloc_meta->free_track[idx], GFP_NOWAIT);
> +}
> +
> +struct kasan_track *kasan_get_free_track(struct kmem_cache *cache,
> +                               void *object, u8 tag)
> +{
> +       struct kasan_alloc_meta *alloc_meta;
> +       int i = 0;
> +
> +       alloc_meta = kasan_get_alloc_meta(cache, object);
> +       if (!alloc_meta)
> +               return NULL;
> +
> +#ifdef CONFIG_KASAN_TAGS_IDENTIFY
> +       for (i = 0; i < KASAN_NR_FREE_STACKS; i++) {
> +               if (alloc_meta->free_pointer_tag[i] == tag)
> +                       break;
> +       }
> +       if (i == KASAN_NR_FREE_STACKS)
> +               i = alloc_meta->free_track_idx;
> +#endif
> +
> +       return &alloc_meta->free_track[i];
> +}
> --
> 2.18.0
>
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