Re: [PATCH v3 35/39] kasan, arm64: implement HW_TAGS runtime

From: elver
Date: Thu Oct 01 2020 - 14:01:06 EST

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On Fri, Sep 25, 2020 at 12:50AM +0200, Andrey Konovalov wrote:
> Provide implementation of KASAN functions required for the hardware
> tag-based mode. Those include core functions for memory and pointer
> tagging (tags_hw.c) and bug reporting (report_tags_hw.c). Also adapt
> common KASAN code to support the new mode.
>
> Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@xxxxxxx>
> Acked-by: Catalin Marinas <catalin.marinas@xxxxxxx>

Reviewed-by: Marco Elver <elver@xxxxxxxxxx>

> ---
> Change-Id: I8a8689ba098174a4d0ef3f1d008178387c80ee1c
> ---
> arch/arm64/include/asm/memory.h | 4 +-
> arch/arm64/kernel/setup.c | 5 ++-
> include/linux/kasan.h | 6 +--
> include/linux/mm.h | 2 +-
> include/linux/page-flags-layout.h | 2 +-
> mm/kasan/Makefile | 5 +++
> mm/kasan/common.c | 15 ++++---
> mm/kasan/hw_tags.c | 70 +++++++++++++++++++++++++++++++
> mm/kasan/kasan.h | 17 ++++++--
> mm/kasan/report_hw_tags.c | 42 +++++++++++++++++++
> mm/kasan/report_sw_tags.c | 2 +-
> mm/kasan/shadow.c | 2 +-
> mm/kasan/sw_tags.c | 2 +-
> 13 files changed, 152 insertions(+), 22 deletions(-)
> create mode 100644 mm/kasan/hw_tags.c
> create mode 100644 mm/kasan/report_hw_tags.c
>
> diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
> index de9af7bea90d..b5d6b824c21c 100644
> --- a/arch/arm64/include/asm/memory.h
> +++ b/arch/arm64/include/asm/memory.h
> @@ -215,7 +215,7 @@ static inline unsigned long kaslr_offset(void)
> (__force __typeof__(addr))__addr; \
> })
>
> -#ifdef CONFIG_KASAN_SW_TAGS
> +#if defined(CONFIG_KASAN_SW_TAGS) || defined(CONFIG_KASAN_HW_TAGS)
> #define __tag_shifted(tag) ((u64)(tag) << 56)
> #define __tag_reset(addr) __untagged_addr(addr)
> #define __tag_get(addr) (__u8)((u64)(addr) >> 56)
> @@ -223,7 +223,7 @@ static inline unsigned long kaslr_offset(void)
> #define __tag_shifted(tag) 0UL
> #define __tag_reset(addr) (addr)
> #define __tag_get(addr) 0
> -#endif /* CONFIG_KASAN_SW_TAGS */
> +#endif /* CONFIG_KASAN_SW_TAGS || CONFIG_KASAN_HW_TAGS */
>
> static inline const void *__tag_set(const void *addr, u8 tag)
> {
> diff --git a/arch/arm64/kernel/setup.c b/arch/arm64/kernel/setup.c
> index 77c4c9bad1b8..b07d9fbfa8b6 100644
> --- a/arch/arm64/kernel/setup.c
> +++ b/arch/arm64/kernel/setup.c
> @@ -358,7 +358,10 @@ void __init __no_sanitize_address setup_arch(char **cmdline_p)
> smp_init_cpus();
> smp_build_mpidr_hash();
>
> - /* Init percpu seeds for random tags after cpus are set up. */
> + /*
> + * For CONFIG_KASAN_SW_TAGS this initializes percpu seeds and must
> + * come after cpus are set up.
> + */
> kasan_init_tags();
>
> #ifdef CONFIG_ARM64_SW_TTBR0_PAN
> diff --git a/include/linux/kasan.h b/include/linux/kasan.h
> index 94b974f15892..80a0e5b11f2b 100644
> --- a/include/linux/kasan.h
> +++ b/include/linux/kasan.h
> @@ -178,7 +178,7 @@ static inline void kasan_record_aux_stack(void *ptr) {}
>
> #endif /* CONFIG_KASAN_GENERIC */
>
> -#ifdef CONFIG_KASAN_SW_TAGS
> +#if defined(CONFIG_KASAN_SW_TAGS) || defined(CONFIG_KASAN_HW_TAGS)
>
> void kasan_init_tags(void);
>
> @@ -187,7 +187,7 @@ void *kasan_reset_tag(const void *addr);
> bool kasan_report(unsigned long addr, size_t size,
> bool is_write, unsigned long ip);
>
> -#else /* CONFIG_KASAN_SW_TAGS */
> +#else /* CONFIG_KASAN_SW_TAGS || CONFIG_KASAN_HW_TAGS */
>
> static inline void kasan_init_tags(void) { }
>
> @@ -196,7 +196,7 @@ static inline void *kasan_reset_tag(const void *addr)
> return (void *)addr;
> }
>
> -#endif /* CONFIG_KASAN_SW_TAGS */
> +#endif /* CONFIG_KASAN_SW_TAGS || CONFIG_KASAN_HW_TAGS*/
>
> #ifdef CONFIG_KASAN_VMALLOC
>
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 4312c6c808e9..a3cac68c737c 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -1411,7 +1411,7 @@ static inline bool cpupid_match_pid(struct task_struct *task, int cpupid)
> }
> #endif /* CONFIG_NUMA_BALANCING */
>
> -#ifdef CONFIG_KASAN_SW_TAGS
> +#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;
> diff --git a/include/linux/page-flags-layout.h b/include/linux/page-flags-layout.h
> index e200eef6a7fd..7d4ec26d8a3e 100644
> --- a/include/linux/page-flags-layout.h
> +++ b/include/linux/page-flags-layout.h
> @@ -77,7 +77,7 @@
> #define LAST_CPUPID_SHIFT 0
> #endif
>
> -#ifdef CONFIG_KASAN_SW_TAGS
> +#if defined(CONFIG_KASAN_SW_TAGS) || defined(CONFIG_KASAN_HW_TAGS)
> #define KASAN_TAG_WIDTH 8
> #else
> #define KASAN_TAG_WIDTH 0
> diff --git a/mm/kasan/Makefile b/mm/kasan/Makefile
> index f1d68a34f3c9..9fe39a66388a 100644
> --- a/mm/kasan/Makefile
> +++ b/mm/kasan/Makefile
> @@ -10,8 +10,10 @@ CFLAGS_REMOVE_init.o = $(CC_FLAGS_FTRACE)
> CFLAGS_REMOVE_quarantine.o = $(CC_FLAGS_FTRACE)
> CFLAGS_REMOVE_report.o = $(CC_FLAGS_FTRACE)
> CFLAGS_REMOVE_report_generic.o = $(CC_FLAGS_FTRACE)
> +CFLAGS_REMOVE_report_hw_tags.o = $(CC_FLAGS_FTRACE)
> CFLAGS_REMOVE_report_sw_tags.o = $(CC_FLAGS_FTRACE)
> CFLAGS_REMOVE_shadow.o = $(CC_FLAGS_FTRACE)
> +CFLAGS_REMOVE_hw_tags.o = $(CC_FLAGS_FTRACE)
> CFLAGS_REMOVE_sw_tags.o = $(CC_FLAGS_FTRACE)
>
> # Function splitter causes unnecessary splits in __asan_load1/__asan_store1
> @@ -27,10 +29,13 @@ CFLAGS_init.o := $(CC_FLAGS_KASAN_RUNTIME)
> CFLAGS_quarantine.o := $(CC_FLAGS_KASAN_RUNTIME)
> CFLAGS_report.o := $(CC_FLAGS_KASAN_RUNTIME)
> CFLAGS_report_generic.o := $(CC_FLAGS_KASAN_RUNTIME)
> +CFLAGS_report_hw_tags.o := $(CC_FLAGS_KASAN_RUNTIME)
> CFLAGS_report_sw_tags.o := $(CC_FLAGS_KASAN_RUNTIME)
> CFLAGS_shadow.o := $(CC_FLAGS_KASAN_RUNTIME)
> +CFLAGS_hw_tags.o := $(CC_FLAGS_KASAN_RUNTIME)
> 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
> diff --git a/mm/kasan/common.c b/mm/kasan/common.c
> index d0b3ff410b0c..2bb0ef6da6bd 100644
> --- a/mm/kasan/common.c
> +++ b/mm/kasan/common.c
> @@ -113,7 +113,7 @@ void kasan_free_pages(struct page *page, unsigned int order)
> */
> static inline unsigned int optimal_redzone(unsigned int object_size)
> {
> - if (IS_ENABLED(CONFIG_KASAN_SW_TAGS))
> + if (!IS_ENABLED(CONFIG_KASAN_GENERIC))
> return 0;
>
> return
> @@ -178,14 +178,14 @@ size_t kasan_metadata_size(struct kmem_cache *cache)
> struct kasan_alloc_meta *get_alloc_info(struct kmem_cache *cache,
> const void *object)
> {
> - return (void *)object + cache->kasan_info.alloc_meta_offset;
> + return (void *)reset_tag(object) + cache->kasan_info.alloc_meta_offset;
> }
>
> struct kasan_free_meta *get_free_info(struct kmem_cache *cache,
> const void *object)
> {
> BUILD_BUG_ON(sizeof(struct kasan_free_meta) > 32);
> - return (void *)object + cache->kasan_info.free_meta_offset;
> + return (void *)reset_tag(object) + cache->kasan_info.free_meta_offset;
> }
>
> void kasan_poison_slab(struct page *page)
> @@ -267,9 +267,8 @@ void * __must_check kasan_init_slab_obj(struct kmem_cache *cache,
> alloc_info = get_alloc_info(cache, object);
> __memset(alloc_info, 0, sizeof(*alloc_info));
>
> - if (IS_ENABLED(CONFIG_KASAN_SW_TAGS))
> - object = set_tag(object,
> - assign_tag(cache, object, true, false));
> + if (IS_ENABLED(CONFIG_KASAN_SW_TAGS) || IS_ENABLED(CONFIG_KASAN_HW_TAGS))
> + object = set_tag(object, assign_tag(cache, object, true, false));
>
> return (void *)object;
> }
> @@ -337,10 +336,10 @@ static void *__kasan_kmalloc(struct kmem_cache *cache, const void *object,
> redzone_end = round_up((unsigned long)object + cache->object_size,
> KASAN_GRANULE_SIZE);
>
> - if (IS_ENABLED(CONFIG_KASAN_SW_TAGS))
> + if (IS_ENABLED(CONFIG_KASAN_SW_TAGS) || IS_ENABLED(CONFIG_KASAN_HW_TAGS))
> tag = assign_tag(cache, object, false, keep_tag);
>
> - /* Tag is ignored in set_tag without CONFIG_KASAN_SW_TAGS */
> + /* Tag is ignored in set_tag without CONFIG_KASAN_SW/HW_TAGS */
> kasan_unpoison_memory(set_tag(object, tag), size);
> kasan_poison_memory((void *)redzone_start, redzone_end - redzone_start,
> KASAN_KMALLOC_REDZONE);
> diff --git a/mm/kasan/hw_tags.c b/mm/kasan/hw_tags.c
> new file mode 100644
> index 000000000000..7f0568df2a93
> --- /dev/null
> +++ b/mm/kasan/hw_tags.c
> @@ -0,0 +1,70 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * This file contains core hardware tag-based KASAN code.
> + *
> + * Copyright (c) 2020 Google, Inc.
> + * Author: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
> + */
> +
> +#include <linux/kasan.h>
> +#include <linux/kernel.h>
> +#include <linux/memory.h>
> +#include <linux/mm.h>
> +#include <linux/string.h>
> +#include <linux/types.h>
> +
> +#include "kasan.h"
> +
> +void kasan_init_tags(void)
> +{
> + init_tags(KASAN_TAG_MAX);
> +}
> +
> +void *kasan_reset_tag(const void *addr)
> +{
> + return reset_tag(addr);
> +}
> +
> +void kasan_poison_memory(const void *address, size_t size, u8 value)
> +{
> + set_mem_tag_range(reset_tag(address),
> + round_up(size, KASAN_GRANULE_SIZE), value);
> +}
> +
> +void kasan_unpoison_memory(const void *address, size_t size)
> +{
> + set_mem_tag_range(reset_tag(address),
> + round_up(size, KASAN_GRANULE_SIZE), get_tag(address));
> +}
> +
> +u8 random_tag(void)
> +{
> + return get_random_tag();
> +}
> +
> +bool check_invalid_free(void *addr)
> +{
> + u8 ptr_tag = get_tag(addr);
> + u8 mem_tag = get_mem_tag(addr);
> +
> + return (mem_tag == KASAN_TAG_INVALID) ||
> + (ptr_tag != KASAN_TAG_KERNEL && ptr_tag != mem_tag);
> +}
> +
> +void kasan_set_free_info(struct kmem_cache *cache,
> + void *object, u8 tag)
> +{
> + struct kasan_alloc_meta *alloc_meta;
> +
> + alloc_meta = get_alloc_info(cache, object);
> + 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 = get_alloc_info(cache, object);
> + return &alloc_meta->free_track[0];
> +}
> diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
> index bd51ab72c002..6661ab4dbe3c 100644
> --- a/mm/kasan/kasan.h
> +++ b/mm/kasan/kasan.h
> @@ -153,6 +153,10 @@ struct kasan_alloc_meta *get_alloc_info(struct kmem_cache *cache,
> struct kasan_free_meta *get_free_info(struct kmem_cache *cache,
> const void *object);
>
> +void kasan_poison_memory(const void *address, size_t size, u8 value);
> +
> +#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
> +
> static inline const void *kasan_shadow_to_mem(const void *shadow_addr)
> {
> return (void *)(((unsigned long)shadow_addr - KASAN_SHADOW_OFFSET)
> @@ -164,8 +168,6 @@ static inline bool addr_has_metadata(const void *addr)
> return (addr >= kasan_shadow_to_mem((void *)KASAN_SHADOW_START));
> }
>
> -void kasan_poison_memory(const void *address, size_t size, u8 value);
> -
> /**
> * check_memory_region - Check memory region, and report if invalid access.
> * @addr: the accessed address
> @@ -177,6 +179,15 @@ void kasan_poison_memory(const void *address, size_t size, u8 value);
> bool check_memory_region(unsigned long addr, size_t size, bool write,
> unsigned long ret_ip);
>
> +#else /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS */
> +
> +static inline bool addr_has_metadata(const void *addr)
> +{
> + return true;
> +}
> +
> +#endif /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS */
> +
> bool check_invalid_free(void *addr);
>
> void *find_first_bad_addr(void *addr, size_t size);
> @@ -213,7 +224,7 @@ static inline void quarantine_reduce(void) { }
> static inline void quarantine_remove_cache(struct kmem_cache *cache) { }
> #endif
>
> -#ifdef CONFIG_KASAN_SW_TAGS
> +#if defined(CONFIG_KASAN_SW_TAGS) || defined(CONFIG_KASAN_HW_TAGS)
>
> void print_tags(u8 addr_tag, const void *addr);
>
> diff --git a/mm/kasan/report_hw_tags.c b/mm/kasan/report_hw_tags.c
> new file mode 100644
> index 000000000000..d8423d1e3b6b
> --- /dev/null
> +++ b/mm/kasan/report_hw_tags.c
> @@ -0,0 +1,42 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * This file contains hardware tag-based KASAN specific error reporting code.
> + *
> + * Copyright (c) 2020 Google, Inc.
> + * Author: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
> + */
> +
> +#include <linux/kasan.h>
> +#include <linux/kernel.h>
> +#include <linux/memory.h>
> +#include <linux/mm.h>
> +#include <linux/string.h>
> +#include <linux/types.h>
> +
> +#include "kasan.h"
> +
> +const char *get_bug_type(struct kasan_access_info *info)
> +{
> + return "invalid-access";
> +}
> +
> +void *find_first_bad_addr(void *addr, size_t size)
> +{
> + return reset_tag(addr);
> +}
> +
> +void metadata_fetch_row(char *buffer, void *row)
> +{
> + int i;
> +
> + for (i = 0; i < META_BYTES_PER_ROW; i++)
> + buffer[i] = mte_get_mem_tag(row + i * KASAN_GRANULE_SIZE);
> +}
> +
> +void print_tags(u8 addr_tag, const void *addr)
> +{
> + u8 memory_tag = mte_get_mem_tag((void *)addr);
> +
> + pr_err("Pointer tag: [%02x], memory tag: [%02x]\n",
> + addr_tag, memory_tag);
> +}
> diff --git a/mm/kasan/report_sw_tags.c b/mm/kasan/report_sw_tags.c
> index add2dfe6169c..aebc44a29e83 100644
> --- a/mm/kasan/report_sw_tags.c
> +++ b/mm/kasan/report_sw_tags.c
> @@ -1,6 +1,6 @@
> // SPDX-License-Identifier: GPL-2.0
> /*
> - * This file contains tag-based KASAN specific error reporting code.
> + * This file contains software tag-based KASAN specific error reporting code.
> *
> * Copyright (c) 2014 Samsung Electronics Co., Ltd.
> * Author: Andrey Ryabinin <ryabinin.a.a@xxxxxxxxx>
> diff --git a/mm/kasan/shadow.c b/mm/kasan/shadow.c
> index 1fadd4930d54..616ac64c4a21 100644
> --- a/mm/kasan/shadow.c
> +++ b/mm/kasan/shadow.c
> @@ -107,7 +107,7 @@ void kasan_unpoison_memory(const void *address, size_t size)
>
> if (IS_ENABLED(CONFIG_KASAN_SW_TAGS))
> *shadow = tag;
> - else
> + else /* CONFIG_KASAN_GENERIC */
> *shadow = size & KASAN_GRANULE_MASK;
> }
> }
> diff --git a/mm/kasan/sw_tags.c b/mm/kasan/sw_tags.c
> index b2638c2cd58a..ccc35a311179 100644
> --- a/mm/kasan/sw_tags.c
> +++ b/mm/kasan/sw_tags.c
> @@ -1,6 +1,6 @@
> // SPDX-License-Identifier: GPL-2.0
> /*
> - * This file contains core tag-based KASAN code.
> + * This file contains core software tag-based KASAN code.
> *
> * Copyright (c) 2018 Google, Inc.
> * Author: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
> --
> 2.28.0.681.g6f77f65b4e-goog
>

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