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

From: Marco Elver
Date: Mon Jun 28 2021 - 02:00:34 EST

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In reply to: Andrey Konovalov: "Re: [PATCH v4 2/3] kasan: integrate the common part of two KASAN tag-based modes"
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On Sat, 26 Jun 2021 at 12:09, Kuan-Ying Lee <Kuan-Ying.Lee@xxxxxxxxxxxx> 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@xxxxxxxxxxxx>
> Suggested-by: Marco Elver <elver@xxxxxxxxxx>
> Suggested-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> Cc: Andrey Ryabinin <ryabinin.a.a@xxxxxxxxx>
> Cc: Alexander Potapenko <glider@xxxxxxxxxx>
> Cc: Andrey Konovalov <andreyknvl@xxxxxxxxx>
> Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>

Reviewed-by: Marco Elver <elver@xxxxxxxxxx>

> ---
> 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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Next message: Marco Elver: "Re: [PATCH v4 3/3] kasan: add memory corruption identification support for hardware tag-based mode"
Previous message: Marco Elver: "Re: [PATCH v4 1/3] kasan: rename CONFIG_KASAN_SW_TAGS_IDENTIFY to CONFIG_KASAN_TAGS_IDENTIFY"
In reply to: Andrey Konovalov: "Re: [PATCH v4 2/3] kasan: integrate the common part of two KASAN tag-based modes"
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