[PATCH v8 38/43] kasan, arm64: implement HW_TAGS runtime

Andrey Konovalov
2020-11-04T23:20:45Z

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/cpufeature.c | 3 ++
include/linux/kasan.h | 22 ++++++---
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 | 76 +++++++++++++++++++++++++++++++
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, 169 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 507012ed24f4..b245554984a2 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..b66a96525a3e 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();
}
#endif /* CONFIG_ARM64_MTE */

diff --git a/include/linux/kasan.h b/include/linux/kasan.h
index beb699e90e55..c6bf762eb88c 100644
--- a/include/linux/kasan.h
+++ b/include/linux/kasan.h
@@ -187,25 +187,33 @@ 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 __init kasan_init_hw_tags(void);
+#else
+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..bdb684c65561
--- /dev/null
+++ b/mm/kasan/hw_tags.c
@@ -0,0 +1,76 @@
+// 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() is called for each CPU. */
+void __init kasan_init_hw_tags(void)
+{
+ hw_init_tags(KASAN_TAG_MAX);
+
+ if (smp_processor_id() == 0)
+ 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 618e69d12f61..b0a57d8f9803 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 PageSlab(virt_to_head_page(addr));
+}
+
+#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>
--
2.29.1.341.ge80a0c044ae-goog