[PATCH v2 1/4] mm/kasan: Introduce __kasan_check_{read,write}
From: Marco Elver
Date: Wed Jun 26 2019 - 08:23:15 EST
This introduces __kasan_check_{read,write} which return a bool if the
access was valid or not. __kasan_check functions may be used from
anywhere, even compilation units that disable instrumentation
selectively. For consistency, kasan_check_{read,write} have been changed
to also return a bool.
This change eliminates the need for the __KASAN_INTERNAL definition.
Signed-off-by: Marco Elver <elver@xxxxxxxxxx>
Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Cc: Pekka Enberg <penberg@xxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: kasan-dev@xxxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: linux-mm@xxxxxxxxx
---
include/linux/kasan-checks.h | 35 ++++++++++++++++++++++++++++-------
mm/kasan/common.c | 14 ++++++--------
mm/kasan/generic.c | 13 +++++++------
mm/kasan/kasan.h | 10 +++++++++-
mm/kasan/tags.c | 12 +++++++-----
5 files changed, 57 insertions(+), 27 deletions(-)
diff --git a/include/linux/kasan-checks.h b/include/linux/kasan-checks.h
index a61dc075e2ce..b8cf8a7cad34 100644
--- a/include/linux/kasan-checks.h
+++ b/include/linux/kasan-checks.h
@@ -2,14 +2,35 @@
#ifndef _LINUX_KASAN_CHECKS_H
#define _LINUX_KASAN_CHECKS_H
-#if defined(__SANITIZE_ADDRESS__) || defined(__KASAN_INTERNAL)
-void kasan_check_read(const volatile void *p, unsigned int size);
-void kasan_check_write(const volatile void *p, unsigned int size);
+/*
+ * __kasan_check_*: Always available when KASAN is enabled. This may be used
+ * even in compilation units that selectively disable KASAN, but must use KASAN
+ * to validate access to an address. Never use these in header files!
+ */
+#ifdef CONFIG_KASAN
+bool __kasan_check_read(const volatile void *p, unsigned int size);
+bool __kasan_check_write(const volatile void *p, unsigned int size);
#else
-static inline void kasan_check_read(const volatile void *p, unsigned int size)
-{ }
-static inline void kasan_check_write(const volatile void *p, unsigned int size)
-{ }
+static inline bool __kasan_check_read(const volatile void *p, unsigned int size)
+{ return true; }
+static inline bool __kasan_check_write(const volatile void *p, unsigned int size)
+{ return true; }
+#endif
+
+/*
+ * kasan_check_*: Only available when the particular compilation unit has KASAN
+ * instrumentation enabled. May be used in header files.
+ */
+#ifdef __SANITIZE_ADDRESS__
+static inline bool kasan_check_read(const volatile void *p, unsigned int size)
+{ return __kasan_check_read(p, size); }
+static inline bool kasan_check_write(const volatile void *p, unsigned int size)
+{ return __kasan_check_read(p, size); }
+#else
+static inline bool kasan_check_read(const volatile void *p, unsigned int size)
+{ return true; }
+static inline bool kasan_check_write(const volatile void *p, unsigned int size)
+{ return true; }
#endif
#endif
diff --git a/mm/kasan/common.c b/mm/kasan/common.c
index 242fdc01aaa9..2277b82902d8 100644
--- a/mm/kasan/common.c
+++ b/mm/kasan/common.c
@@ -14,8 +14,6 @@
*
*/
-#define __KASAN_INTERNAL
-
#include <linux/export.h>
#include <linux/interrupt.h>
#include <linux/init.h>
@@ -89,17 +87,17 @@ void kasan_disable_current(void)
current->kasan_depth--;
}
-void kasan_check_read(const volatile void *p, unsigned int size)
+bool __kasan_check_read(const volatile void *p, unsigned int size)
{
- check_memory_region((unsigned long)p, size, false, _RET_IP_);
+ return check_memory_region((unsigned long)p, size, false, _RET_IP_);
}
-EXPORT_SYMBOL(kasan_check_read);
+EXPORT_SYMBOL(__kasan_check_read);
-void kasan_check_write(const volatile void *p, unsigned int size)
+bool __kasan_check_write(const volatile void *p, unsigned int size)
{
- check_memory_region((unsigned long)p, size, true, _RET_IP_);
+ return check_memory_region((unsigned long)p, size, true, _RET_IP_);
}
-EXPORT_SYMBOL(kasan_check_write);
+EXPORT_SYMBOL(__kasan_check_write);
#undef memset
void *memset(void *addr, int c, size_t len)
diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c
index 504c79363a34..616f9dd82d12 100644
--- a/mm/kasan/generic.c
+++ b/mm/kasan/generic.c
@@ -166,29 +166,30 @@ static __always_inline bool memory_is_poisoned(unsigned long addr, size_t size)
return memory_is_poisoned_n(addr, size);
}
-static __always_inline void check_memory_region_inline(unsigned long addr,
+static __always_inline bool check_memory_region_inline(unsigned long addr,
size_t size, bool write,
unsigned long ret_ip)
{
if (unlikely(size == 0))
- return;
+ return true;
if (unlikely((void *)addr <
kasan_shadow_to_mem((void *)KASAN_SHADOW_START))) {
kasan_report(addr, size, write, ret_ip);
- return;
+ return false;
}
if (likely(!memory_is_poisoned(addr, size)))
- return;
+ return true;
kasan_report(addr, size, write, ret_ip);
+ return false;
}
-void check_memory_region(unsigned long addr, size_t size, bool write,
+bool check_memory_region(unsigned long addr, size_t size, bool write,
unsigned long ret_ip)
{
- check_memory_region_inline(addr, size, write, ret_ip);
+ return check_memory_region_inline(addr, size, write, ret_ip);
}
void kasan_cache_shrink(struct kmem_cache *cache)
diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
index 3ce956efa0cb..e62ea45d02e3 100644
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h
@@ -123,7 +123,15 @@ static inline bool addr_has_shadow(const void *addr)
void kasan_poison_shadow(const void *address, size_t size, u8 value);
-void check_memory_region(unsigned long addr, size_t size, bool write,
+/**
+ * check_memory_region - Check memory region, and report if invalid access.
+ * @addr: the accessed address
+ * @size: the accessed size
+ * @write: true if access is a write access
+ * @ret_ip: return address
+ * @return: true if access was valid, false if invalid
+ */
+bool check_memory_region(unsigned long addr, size_t size, bool write,
unsigned long ret_ip);
void *find_first_bad_addr(void *addr, size_t size);
diff --git a/mm/kasan/tags.c b/mm/kasan/tags.c
index 63fca3172659..0e987c9ca052 100644
--- a/mm/kasan/tags.c
+++ b/mm/kasan/tags.c
@@ -76,7 +76,7 @@ void *kasan_reset_tag(const void *addr)
return reset_tag(addr);
}
-void check_memory_region(unsigned long addr, size_t size, bool write,
+bool check_memory_region(unsigned long addr, size_t size, bool write,
unsigned long ret_ip)
{
u8 tag;
@@ -84,7 +84,7 @@ void check_memory_region(unsigned long addr, size_t size, bool write,
void *untagged_addr;
if (unlikely(size == 0))
- return;
+ return true;
tag = get_tag((const void *)addr);
@@ -106,22 +106,24 @@ void check_memory_region(unsigned long addr, size_t size, bool write,
* set to KASAN_TAG_KERNEL (0xFF)).
*/
if (tag == KASAN_TAG_KERNEL)
- return;
+ return true;
untagged_addr = reset_tag((const void *)addr);
if (unlikely(untagged_addr <
kasan_shadow_to_mem((void *)KASAN_SHADOW_START))) {
kasan_report(addr, size, write, ret_ip);
- return;
+ return false;
}
shadow_first = kasan_mem_to_shadow(untagged_addr);
shadow_last = kasan_mem_to_shadow(untagged_addr + size - 1);
for (shadow = shadow_first; shadow <= shadow_last; shadow++) {
if (*shadow != tag) {
kasan_report(addr, size, write, ret_ip);
- return;
+ return false;
}
}
+
+ return true;
}
#define DEFINE_HWASAN_LOAD_STORE(size) \
--
2.22.0.410.gd8fdbe21b5-goog