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

Andrey Konovalov
2020-09-24T22:52:33Z

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>
---
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@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"
+
+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@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] = 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@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 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@google.com>
--
2.28.0.681.g6f77f65b4e-goog