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    SubjectRe: [PATCH v9 39/44] kasan, arm64: implement HW_TAGS runtime
    On Tue, Nov 10, 2020 at 11:12 PM Andrey Konovalov <andreyknvl@google.com> 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@google.com>
    > Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
    > Acked-by: Catalin Marinas <catalin.marinas@arm.com>
    Reviewed-by: Alexander Potapenko <glider@google.com>

    > ---
    > Change-Id: I8a8689ba098174a4d0ef3f1d008178387c80ee1c
    > ---
    > arch/arm64/include/asm/memory.h | 4 +-
    > arch/arm64/kernel/cpufeature.c | 3 ++
    > arch/arm64/kernel/smp.c | 2 +
    > include/linux/kasan.h | 24 +++++++---
    > 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 | 80 +++++++++++++++++++++++++++++++
    > 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 +-
    > 14 files changed, 177 insertions(+), 25 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 656aaddb7014..5042eef5b111 100644
    > --- a/arch/arm64/include/asm/memory.h
    > +++ b/arch/arm64/include/asm/memory.h
    > @@ -214,7 +214,7 @@ 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)
    > @@ -222,7 +222,7 @@ 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/cpufeature.c b/arch/arm64/kernel/cpufeature.c
    > index dcc165b3fc04..6a1f2e3558c5 100644
    > --- a/arch/arm64/kernel/cpufeature.c
    > +++ b/arch/arm64/kernel/cpufeature.c
    > @@ -70,6 +70,7 @@
    > #include <linux/types.h>
    > #include <linux/mm.h>
    > #include <linux/cpu.h>
    > +#include <linux/kasan.h>
    > #include <asm/cpu.h>
    > #include <asm/cpufeature.h>
    > #include <asm/cpu_ops.h>
    > @@ -1704,6 +1705,8 @@ static void cpu_enable_mte(struct arm64_cpu_capabilities const *cap)
    > cleared_zero_page = true;
    > mte_clear_page_tags(lm_alias(empty_zero_page));
    > }
    > +
    > + kasan_init_hw_tags_cpu();
    > }
    > #endif /* CONFIG_ARM64_MTE */
    >
    > diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
    > index 09c96f57818c..7235b9478413 100644
    > --- a/arch/arm64/kernel/smp.c
    > +++ b/arch/arm64/kernel/smp.c
    > @@ -461,6 +461,8 @@ void __init smp_prepare_boot_cpu(void)
    > /* Conditionally switch to GIC PMR for interrupt masking */
    > if (system_uses_irq_prio_masking())
    > init_gic_priority_masking();
    > +
    > + kasan_init_hw_tags();
    > }
    >
    > static u64 __init of_get_cpu_mpidr(struct device_node *dn)
    > diff --git a/include/linux/kasan.h b/include/linux/kasan.h
    > index b6fc14b3da53..f22bdef82111 100644
    > --- a/include/linux/kasan.h
    > +++ b/include/linux/kasan.h
    > @@ -189,25 +189,35 @@ static inline void kasan_record_aux_stack(void *ptr) {}
    >
    > #endif /* CONFIG_KASAN_GENERIC */
    >
    > -#ifdef CONFIG_KASAN_SW_TAGS
    > -
    > -void __init kasan_init_sw_tags(void);
    > +#if defined(CONFIG_KASAN_SW_TAGS) || defined(CONFIG_KASAN_HW_TAGS)
    >
    > 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 */
    > -
    > -static inline void kasan_init_sw_tags(void) { }
    > +#else /* CONFIG_KASAN_SW_TAGS || CONFIG_KASAN_HW_TAGS */
    >
    > 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_SW_TAGS
    > +void __init kasan_init_sw_tags(void);
    > +#else
    > +static inline void kasan_init_sw_tags(void) { }
    > +#endif
    > +
    > +#ifdef CONFIG_KASAN_HW_TAGS
    > +void kasan_init_hw_tags_cpu(void);
    > +void kasan_init_hw_tags(void);
    > +#else
    > +static inline void kasan_init_hw_tags_cpu(void) { }
    > +static inline void kasan_init_hw_tags(void) { }
    > +#endif
    >
    > #ifdef CONFIG_KASAN_VMALLOC
    >
    > diff --git a/include/linux/mm.h b/include/linux/mm.h
    > index db6ae4d3fb4e..0793d03a4183 100644
    > --- a/include/linux/mm.h
    > +++ b/include/linux/mm.h
    > @@ -1413,7 +1413,7 @@ 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..0080b78ec843
    > --- /dev/null
    > +++ b/mm/kasan/hw_tags.c
    > @@ -0,0 +1,80 @@
    > +// SPDX-License-Identifier: GPL-2.0
    > +/*
    > + * This file contains core hardware tag-based KASAN code.
    > + *
    > + * Copyright (c) 2020 Google, Inc.
    > + * Author: Andrey Konovalov <andreyknvl@google.com>
    > + */
    > +
    > +#define pr_fmt(fmt) "kasan: " fmt
    > +
    > +#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"
    > +
    > +/* kasan_init_hw_tags_cpu() is called for each CPU. */
    > +void kasan_init_hw_tags_cpu(void)
    > +{
    > + hw_init_tags(KASAN_TAG_MAX);
    > + hw_enable_tagging();
    > +}
    > +
    > +/* kasan_init_hw_tags() is called once on boot CPU. */
    > +void kasan_init_hw_tags(void)
    > +{
    > + pr_info("KernelAddressSanitizer initialized\n");
    > +}
    > +
    > +void *kasan_reset_tag(const void *addr)
    > +{
    > + return reset_tag(addr);
    > +}
    > +
    > +void kasan_poison_memory(const void *address, size_t size, u8 value)
    > +{
    > + hw_set_mem_tag_range(reset_tag(address),
    > + round_up(size, KASAN_GRANULE_SIZE), value);
    > +}
    > +
    > +void kasan_unpoison_memory(const void *address, size_t size)
    > +{
    > + hw_set_mem_tag_range(reset_tag(address),
    > + round_up(size, KASAN_GRANULE_SIZE), get_tag(address));
    > +}
    > +
    > +u8 random_tag(void)
    > +{
    > + return hw_get_random_tag();
    > +}
    > +
    > +bool check_invalid_free(void *addr)
    > +{
    > + u8 ptr_tag = get_tag(addr);
    > + u8 mem_tag = hw_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 d745a78745dd..21fe75c66f26 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..da543eb832cd
    > --- /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@google.com>
    > + */
    > +
    > +#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] = hw_get_mem_tag(row + i * KASAN_GRANULE_SIZE);
    > +}
    > +
    > +void print_tags(u8 addr_tag, const void *addr)
    > +{
    > + u8 memory_tag = hw_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@gmail.com>
    > 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 b09a2c06abad..dfe707dd8d0d 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@google.com>
    > --
    > 2.29.2.222.g5d2a92d10f8-goog
    >


    --
    Alexander Potapenko
    Software Engineer

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

    Geschäftsführer: Paul Manicle, Halimah DeLaine Prado
    Registergericht und -nummer: Hamburg, HRB 86891
    Sitz der Gesellschaft: Hamburg

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