Thread (90 messages) 90 messages, 5 authors, 2020-09-24

Re: [PATCH v2 05/37] kasan: rename KASAN_SHADOW_* to KASAN_GRANULE_*

From: Alexander Potapenko <glider@google.com>
Date: 2020-09-18 08:04:21
Also in: linux-mm, lkml

On Tue, Sep 15, 2020 at 11:16 PM Andrey Konovalov [off-list ref] wrote:
This is a preparatory commit for the upcoming addition of a new hardware
tag-based (MTE-based) KASAN mode.

The new mode won't be using shadow memory, but will still use the concept
of memory granules.
KASAN documentation doesn't seem to explain this concept anywhere (I
also checked the "kasan: add documentation for hardware tag-based
mode" patch), looks like it's only mentioned in MTE documentation.
Could you please elaborate on what we consider a granule in each of KASAN modes?
quoted hunk ↗ jump to hunk
Rename KASAN_SHADOW_SCALE_SIZE to KASAN_GRANULE_SIZE,
and KASAN_SHADOW_MASK to KASAN_GRANULE_MASK.

Also use MASK when used as a mask, otherwise use SIZE.

No functional changes.

Signed-off-by: Andrey Konovalov <redacted>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
---
Change-Id: Iac733e2248aa9d29f6fc425d8946ba07cca73ecf
---
 Documentation/dev-tools/kasan.rst |  2 +-
 lib/test_kasan.c                  |  2 +-
 mm/kasan/common.c                 | 39 ++++++++++++++++---------------
 mm/kasan/generic.c                | 14 +++++------
 mm/kasan/generic_report.c         |  8 +++----
 mm/kasan/init.c                   |  8 +++----
 mm/kasan/kasan.h                  |  4 ++--
 mm/kasan/report.c                 | 10 ++++----
 mm/kasan/tags_report.c            |  2 +-
 9 files changed, 45 insertions(+), 44 deletions(-)
diff --git a/Documentation/dev-tools/kasan.rst b/Documentation/dev-tools/kasan.rst
index 38fd5681fade..a3030fc6afe5 100644
--- a/Documentation/dev-tools/kasan.rst
+++ b/Documentation/dev-tools/kasan.rst
@@ -264,7 +264,7 @@ Most mappings in vmalloc space are small, requiring less than a full
 page of shadow space. Allocating a full shadow page per mapping would
 therefore be wasteful. Furthermore, to ensure that different mappings
 use different shadow pages, mappings would have to be aligned to
-``KASAN_SHADOW_SCALE_SIZE * PAGE_SIZE``.
+``KASAN_GRANULE_SIZE * PAGE_SIZE``.

 Instead, we share backing space across multiple mappings. We allocate
 a backing page when a mapping in vmalloc space uses a particular page
diff --git a/lib/test_kasan.c b/lib/test_kasan.c
index 53e953bb1d1d..ddd0b80f24a1 100644
--- a/lib/test_kasan.c
+++ b/lib/test_kasan.c
@@ -25,7 +25,7 @@

 #include "../mm/kasan/kasan.h"

-#define OOB_TAG_OFF (IS_ENABLED(CONFIG_KASAN_GENERIC) ? 0 : KASAN_SHADOW_SCALE_SIZE)
+#define OOB_TAG_OFF (IS_ENABLED(CONFIG_KASAN_GENERIC) ? 0 : KASAN_GRANULE_SIZE)

 /*
  * We assign some test results to these globals to make sure the tests
diff --git a/mm/kasan/common.c b/mm/kasan/common.c
index 65933b27df81..c9daf2c33651 100644
--- a/mm/kasan/common.c
+++ b/mm/kasan/common.c
@@ -111,7 +111,7 @@ void *memcpy(void *dest, const void *src, size_t len)

 /*
  * Poisons the shadow memory for 'size' bytes starting from 'addr'.
- * Memory addresses should be aligned to KASAN_SHADOW_SCALE_SIZE.
+ * Memory addresses should be aligned to KASAN_GRANULE_SIZE.
  */
 void kasan_poison_memory(const void *address, size_t size, u8 value)
 {
@@ -143,13 +143,13 @@ void kasan_unpoison_memory(const void *address, size_t size)

        kasan_poison_memory(address, size, tag);

-       if (size & KASAN_SHADOW_MASK) {
+       if (size & KASAN_GRANULE_MASK) {
                u8 *shadow = (u8 *)kasan_mem_to_shadow(address + size);

                if (IS_ENABLED(CONFIG_KASAN_SW_TAGS))
                        *shadow = tag;
                else
-                       *shadow = size & KASAN_SHADOW_MASK;
+                       *shadow = size & KASAN_GRANULE_MASK;
        }
 }
@@ -301,7 +301,7 @@ void kasan_unpoison_object_data(struct kmem_cache *cache, void *object)
 void kasan_poison_object_data(struct kmem_cache *cache, void *object)
 {
        kasan_poison_memory(object,
-                       round_up(cache->object_size, KASAN_SHADOW_SCALE_SIZE),
+                       round_up(cache->object_size, KASAN_GRANULE_SIZE),
                        KASAN_KMALLOC_REDZONE);
 }
@@ -373,7 +373,7 @@ static inline bool shadow_invalid(u8 tag, s8 shadow_byte)
 {
        if (IS_ENABLED(CONFIG_KASAN_GENERIC))
                return shadow_byte < 0 ||
-                       shadow_byte >= KASAN_SHADOW_SCALE_SIZE;
+                       shadow_byte >= KASAN_GRANULE_SIZE;

        /* else CONFIG_KASAN_SW_TAGS: */
        if ((u8)shadow_byte == KASAN_TAG_INVALID)
@@ -412,7 +412,7 @@ static bool __kasan_slab_free(struct kmem_cache *cache, void *object,
                return true;
        }

-       rounded_up_size = round_up(cache->object_size, KASAN_SHADOW_SCALE_SIZE);
+       rounded_up_size = round_up(cache->object_size, KASAN_GRANULE_SIZE);
        kasan_poison_memory(object, rounded_up_size, KASAN_KMALLOC_FREE);

        if ((IS_ENABLED(CONFIG_KASAN_GENERIC) && !quarantine) ||
@@ -445,9 +445,9 @@ static void *__kasan_kmalloc(struct kmem_cache *cache, const void *object,
                return NULL;

        redzone_start = round_up((unsigned long)(object + size),
-                               KASAN_SHADOW_SCALE_SIZE);
+                               KASAN_GRANULE_SIZE);
        redzone_end = round_up((unsigned long)object + cache->object_size,
-                               KASAN_SHADOW_SCALE_SIZE);
+                               KASAN_GRANULE_SIZE);

        if (IS_ENABLED(CONFIG_KASAN_SW_TAGS))
                tag = assign_tag(cache, object, false, keep_tag);
@@ -491,7 +491,7 @@ void * __must_check kasan_kmalloc_large(const void *ptr, size_t size,

        page = virt_to_page(ptr);
        redzone_start = round_up((unsigned long)(ptr + size),
-                               KASAN_SHADOW_SCALE_SIZE);
+                               KASAN_GRANULE_SIZE);
        redzone_end = (unsigned long)ptr + page_size(page);

        kasan_unpoison_memory(ptr, size);
@@ -589,8 +589,8 @@ static int __meminit kasan_mem_notifier(struct notifier_block *nb,
        shadow_size = nr_shadow_pages << PAGE_SHIFT;
        shadow_end = shadow_start + shadow_size;

-       if (WARN_ON(mem_data->nr_pages % KASAN_SHADOW_SCALE_SIZE) ||
-               WARN_ON(start_kaddr % (KASAN_SHADOW_SCALE_SIZE << PAGE_SHIFT)))
+       if (WARN_ON(mem_data->nr_pages % KASAN_GRANULE_SIZE) ||
+               WARN_ON(start_kaddr % (KASAN_GRANULE_SIZE << PAGE_SHIFT)))
                return NOTIFY_BAD;

        switch (action) {
@@ -748,7 +748,7 @@ void kasan_poison_vmalloc(const void *start, unsigned long size)
        if (!is_vmalloc_or_module_addr(start))
                return;

-       size = round_up(size, KASAN_SHADOW_SCALE_SIZE);
+       size = round_up(size, KASAN_GRANULE_SIZE);
        kasan_poison_memory(start, size, KASAN_VMALLOC_INVALID);
 }
@@ -861,22 +861,22 @@ void kasan_release_vmalloc(unsigned long start, unsigned long end,
        unsigned long region_start, region_end;
        unsigned long size;

-       region_start = ALIGN(start, PAGE_SIZE * KASAN_SHADOW_SCALE_SIZE);
-       region_end = ALIGN_DOWN(end, PAGE_SIZE * KASAN_SHADOW_SCALE_SIZE);
+       region_start = ALIGN(start, PAGE_SIZE * KASAN_GRANULE_SIZE);
+       region_end = ALIGN_DOWN(end, PAGE_SIZE * KASAN_GRANULE_SIZE);

        free_region_start = ALIGN(free_region_start,
-                                 PAGE_SIZE * KASAN_SHADOW_SCALE_SIZE);
+                                 PAGE_SIZE * KASAN_GRANULE_SIZE);

        if (start != region_start &&
            free_region_start < region_start)
-               region_start -= PAGE_SIZE * KASAN_SHADOW_SCALE_SIZE;
+               region_start -= PAGE_SIZE * KASAN_GRANULE_SIZE;

        free_region_end = ALIGN_DOWN(free_region_end,
-                                    PAGE_SIZE * KASAN_SHADOW_SCALE_SIZE);
+                                    PAGE_SIZE * KASAN_GRANULE_SIZE);

        if (end != region_end &&
            free_region_end > region_end)
-               region_end += PAGE_SIZE * KASAN_SHADOW_SCALE_SIZE;
+               region_end += PAGE_SIZE * KASAN_GRANULE_SIZE;

        shadow_start = kasan_mem_to_shadow((void *)region_start);
        shadow_end = kasan_mem_to_shadow((void *)region_end);
@@ -902,7 +902,8 @@ int kasan_module_alloc(void *addr, size_t size)
        unsigned long shadow_start;

        shadow_start = (unsigned long)kasan_mem_to_shadow(addr);
-       scaled_size = (size + KASAN_SHADOW_MASK) >> KASAN_SHADOW_SCALE_SHIFT;
+       scaled_size = (size + KASAN_GRANULE_SIZE - 1) >>
+                               KASAN_SHADOW_SCALE_SHIFT;
        shadow_size = round_up(scaled_size, PAGE_SIZE);

        if (WARN_ON(!PAGE_ALIGNED(shadow_start)))
diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c
index 4b5f905198d8..f6d68aa9872f 100644
--- a/mm/kasan/generic.c
+++ b/mm/kasan/generic.c
@@ -51,7 +51,7 @@ static __always_inline bool memory_is_poisoned_1(unsigned long addr)
        s8 shadow_value = *(s8 *)kasan_mem_to_shadow((void *)addr);

        if (unlikely(shadow_value)) {
-               s8 last_accessible_byte = addr & KASAN_SHADOW_MASK;
+               s8 last_accessible_byte = addr & KASAN_GRANULE_MASK;
                return unlikely(last_accessible_byte >= shadow_value);
        }
@@ -67,7 +67,7 @@ static __always_inline bool memory_is_poisoned_2_4_8(unsigned long addr,
         * Access crosses 8(shadow size)-byte boundary. Such access maps
         * into 2 shadow bytes, so we need to check them both.
         */
-       if (unlikely(((addr + size - 1) & KASAN_SHADOW_MASK) < size - 1))
+       if (unlikely(((addr + size - 1) & KASAN_GRANULE_MASK) < size - 1))
                return *shadow_addr || memory_is_poisoned_1(addr + size - 1);

        return memory_is_poisoned_1(addr + size - 1);
@@ -78,7 +78,7 @@ static __always_inline bool memory_is_poisoned_16(unsigned long addr)
        u16 *shadow_addr = (u16 *)kasan_mem_to_shadow((void *)addr);

        /* Unaligned 16-bytes access maps into 3 shadow bytes. */
-       if (unlikely(!IS_ALIGNED(addr, KASAN_SHADOW_SCALE_SIZE)))
+       if (unlikely(!IS_ALIGNED(addr, KASAN_GRANULE_SIZE)))
                return *shadow_addr || memory_is_poisoned_1(addr + 15);

        return *shadow_addr;
@@ -139,7 +139,7 @@ static __always_inline bool memory_is_poisoned_n(unsigned long addr,
                s8 *last_shadow = (s8 *)kasan_mem_to_shadow((void *)last_byte);

                if (unlikely(ret != (unsigned long)last_shadow ||
-                       ((long)(last_byte & KASAN_SHADOW_MASK) >= *last_shadow)))
+                       ((long)(last_byte & KASAN_GRANULE_MASK) >= *last_shadow)))
                        return true;
        }
        return false;
@@ -205,7 +205,7 @@ void kasan_cache_shutdown(struct kmem_cache *cache)

 static void register_global(struct kasan_global *global)
 {
-       size_t aligned_size = round_up(global->size, KASAN_SHADOW_SCALE_SIZE);
+       size_t aligned_size = round_up(global->size, KASAN_GRANULE_SIZE);

        kasan_unpoison_memory(global->beg, global->size);
@@ -279,10 +279,10 @@ EXPORT_SYMBOL(__asan_handle_no_return);
 /* Emitted by compiler to poison alloca()ed objects. */
 void __asan_alloca_poison(unsigned long addr, size_t size)
 {
-       size_t rounded_up_size = round_up(size, KASAN_SHADOW_SCALE_SIZE);
+       size_t rounded_up_size = round_up(size, KASAN_GRANULE_SIZE);
        size_t padding_size = round_up(size, KASAN_ALLOCA_REDZONE_SIZE) -
                        rounded_up_size;
-       size_t rounded_down_size = round_down(size, KASAN_SHADOW_SCALE_SIZE);
+       size_t rounded_down_size = round_down(size, KASAN_GRANULE_SIZE);

        const void *left_redzone = (const void *)(addr -
                        KASAN_ALLOCA_REDZONE_SIZE);
diff --git a/mm/kasan/generic_report.c b/mm/kasan/generic_report.c
index a38c7a9e192a..4dce1633b082 100644
--- a/mm/kasan/generic_report.c
+++ b/mm/kasan/generic_report.c
@@ -39,7 +39,7 @@ void *find_first_bad_addr(void *addr, size_t size)
        void *p = addr;

        while (p < addr + size && !(*(u8 *)kasan_mem_to_shadow(p)))
-               p += KASAN_SHADOW_SCALE_SIZE;
+               p += KASAN_GRANULE_SIZE;
        return p;
 }
@@ -51,14 +51,14 @@ static const char *get_shadow_bug_type(struct kasan_access_info *info)
        shadow_addr = (u8 *)kasan_mem_to_shadow(info->first_bad_addr);

        /*
-        * If shadow byte value is in [0, KASAN_SHADOW_SCALE_SIZE) we can look
+        * If shadow byte value is in [0, KASAN_GRANULE_SIZE) we can look
         * at the next shadow byte to determine the type of the bad access.
         */
-       if (*shadow_addr > 0 && *shadow_addr <= KASAN_SHADOW_SCALE_SIZE - 1)
+       if (*shadow_addr > 0 && *shadow_addr <= KASAN_GRANULE_SIZE - 1)
                shadow_addr++;

        switch (*shadow_addr) {
-       case 0 ... KASAN_SHADOW_SCALE_SIZE - 1:
+       case 0 ... KASAN_GRANULE_SIZE - 1:
                /*
                 * In theory it's still possible to see these shadow values
                 * due to a data race in the kernel code.
diff --git a/mm/kasan/init.c b/mm/kasan/init.c
index fe6be0be1f76..754b641c83c7 100644
--- a/mm/kasan/init.c
+++ b/mm/kasan/init.c
@@ -447,8 +447,8 @@ void kasan_remove_zero_shadow(void *start, unsigned long size)
        end = addr + (size >> KASAN_SHADOW_SCALE_SHIFT);

        if (WARN_ON((unsigned long)start %
-                       (KASAN_SHADOW_SCALE_SIZE * PAGE_SIZE)) ||
-           WARN_ON(size % (KASAN_SHADOW_SCALE_SIZE * PAGE_SIZE)))
+                       (KASAN_GRANULE_SIZE * PAGE_SIZE)) ||
+           WARN_ON(size % (KASAN_GRANULE_SIZE * PAGE_SIZE)))
                return;

        for (; addr < end; addr = next) {
@@ -482,8 +482,8 @@ int kasan_add_zero_shadow(void *start, unsigned long size)
        shadow_end = shadow_start + (size >> KASAN_SHADOW_SCALE_SHIFT);

        if (WARN_ON((unsigned long)start %
-                       (KASAN_SHADOW_SCALE_SIZE * PAGE_SIZE)) ||
-           WARN_ON(size % (KASAN_SHADOW_SCALE_SIZE * PAGE_SIZE)))
+                       (KASAN_GRANULE_SIZE * PAGE_SIZE)) ||
+           WARN_ON(size % (KASAN_GRANULE_SIZE * PAGE_SIZE)))
                return -EINVAL;

        ret = kasan_populate_early_shadow(shadow_start, shadow_end);
diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
index 03450d3b31f7..c31e2c739301 100644
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h
@@ -5,8 +5,8 @@
 #include <linux/kasan.h>
 #include <linux/stackdepot.h>

-#define KASAN_SHADOW_SCALE_SIZE (1UL << KASAN_SHADOW_SCALE_SHIFT)
-#define KASAN_SHADOW_MASK       (KASAN_SHADOW_SCALE_SIZE - 1)
+#define KASAN_GRANULE_SIZE     (1UL << KASAN_SHADOW_SCALE_SHIFT)
+#define KASAN_GRANULE_MASK     (KASAN_GRANULE_SIZE - 1)

 #define KASAN_TAG_KERNEL       0xFF /* native kernel pointers tag */
 #define KASAN_TAG_INVALID      0xFE /* inaccessible memory tag */
diff --git a/mm/kasan/report.c b/mm/kasan/report.c
index 4f49fa6cd1aa..7c025d792e2f 100644
--- a/mm/kasan/report.c
+++ b/mm/kasan/report.c
@@ -317,24 +317,24 @@ static bool __must_check get_address_stack_frame_info(const void *addr,
                return false;

        aligned_addr = round_down((unsigned long)addr, sizeof(long));
-       mem_ptr = round_down(aligned_addr, KASAN_SHADOW_SCALE_SIZE);
+       mem_ptr = round_down(aligned_addr, KASAN_GRANULE_SIZE);
        shadow_ptr = kasan_mem_to_shadow((void *)aligned_addr);
        shadow_bottom = kasan_mem_to_shadow(end_of_stack(current));

        while (shadow_ptr >= shadow_bottom && *shadow_ptr != KASAN_STACK_LEFT) {
                shadow_ptr--;
-               mem_ptr -= KASAN_SHADOW_SCALE_SIZE;
+               mem_ptr -= KASAN_GRANULE_SIZE;
        }

        while (shadow_ptr >= shadow_bottom && *shadow_ptr == KASAN_STACK_LEFT) {
                shadow_ptr--;
-               mem_ptr -= KASAN_SHADOW_SCALE_SIZE;
+               mem_ptr -= KASAN_GRANULE_SIZE;
        }

        if (shadow_ptr < shadow_bottom)
                return false;

-       frame = (const unsigned long *)(mem_ptr + KASAN_SHADOW_SCALE_SIZE);
+       frame = (const unsigned long *)(mem_ptr + KASAN_GRANULE_SIZE);
        if (frame[0] != KASAN_CURRENT_STACK_FRAME_MAGIC) {
                pr_err("KASAN internal error: frame info validation failed; invalid marker: %lu\n",
                       frame[0]);
@@ -572,6 +572,6 @@ void kasan_non_canonical_hook(unsigned long addr)
        else
                bug_type = "maybe wild-memory-access";
        pr_alert("KASAN: %s in range [0x%016lx-0x%016lx]\n", bug_type,
-                orig_addr, orig_addr + KASAN_SHADOW_MASK);
+                orig_addr, orig_addr + KASAN_GRANULE_SIZE - 1);
 }
 #endif
diff --git a/mm/kasan/tags_report.c b/mm/kasan/tags_report.c
index bee43717d6f0..6ddb55676a7c 100644
--- a/mm/kasan/tags_report.c
+++ b/mm/kasan/tags_report.c
@@ -81,7 +81,7 @@ void *find_first_bad_addr(void *addr, size_t size)
        void *end = p + size;

        while (p < end && tag == *(u8 *)kasan_mem_to_shadow(p))
-               p += KASAN_SHADOW_SCALE_SIZE;
+               p += KASAN_GRANULE_SIZE;
        return p;
 }

--
2.28.0.618.gf4bc123cb7-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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