[Devel] [PATCH 29/39] kasan: enable instrumentation of global variables
Andrey Ryabinin
aryabinin at odin.com
Mon Aug 24 03:19:19 PDT 2015
From: Andrey Ryabinin <a.ryabinin at samsung.com>
commit bebf56a1b176c2e1c9efe44e7e6915532cc682cf upstream.
This feature let us to detect accesses out of bounds of global variables.
This will work as for globals in kernel image, so for globals in modules.
Currently this won't work for symbols in user-specified sections (e.g.
__init, __read_mostly, ...)
The idea of this is simple. Compiler increases each global variable by
redzone size and add constructors invoking __asan_register_globals()
function. Information about global variable (address, size, size with
redzone ...) passed to __asan_register_globals() so we could poison
variable's redzone.
This patch also forces module_alloc() to return 8*PAGE_SIZE aligned
address making shadow memory handling (
kasan_module_alloc()/kasan_module_free() ) more simple. Such alignment
guarantees that each shadow page backing modules address space correspond
to only one module_alloc() allocation.
Signed-off-by: Andrey Ryabinin <a.ryabinin at samsung.com>
Cc: Dmitry Vyukov <dvyukov at google.com>
Cc: Konstantin Serebryany <kcc at google.com>
Cc: Dmitry Chernenkov <dmitryc at google.com>
Signed-off-by: Andrey Konovalov <adech.fo at gmail.com>
Cc: Yuri Gribov <tetra2005 at gmail.com>
Cc: Konstantin Khlebnikov <koct9i at gmail.com>
Cc: Sasha Levin <sasha.levin at oracle.com>
Cc: Christoph Lameter <cl at linux.com>
Cc: Joonsoo Kim <iamjoonsoo.kim at lge.com>
Cc: Dave Hansen <dave.hansen at intel.com>
Cc: Andi Kleen <andi at firstfloor.org>
Cc: Ingo Molnar <mingo at elte.hu>
Cc: Thomas Gleixner <tglx at linutronix.de>
Cc: "H. Peter Anvin" <hpa at zytor.com>
Cc: Christoph Lameter <cl at linux.com>
Cc: Pekka Enberg <penberg at kernel.org>
Cc: David Rientjes <rientjes at google.com>
Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
Signed-off-by: Andrey Ryabinin <aryabinin at odin.com>
---
Documentation/kasan.txt | 2 +-
arch/x86/kernel/module.c | 12 +++++++++--
arch/x86/mm/kasan_init_64.c | 4 ++--
include/linux/kasan.h | 10 +++++++++
kernel/module.c | 2 ++
lib/Kconfig.kasan | 1 +
mm/kasan/kasan.c | 52 +++++++++++++++++++++++++++++++++++++++++++++
mm/kasan/kasan.h | 25 ++++++++++++++++++++++
mm/kasan/report.c | 22 +++++++++++++++++++
scripts/Makefile.kasan | 2 +-
10 files changed, 126 insertions(+), 6 deletions(-)
diff --git a/Documentation/kasan.txt b/Documentation/kasan.txt
index f0645a8..092fc10 100644
--- a/Documentation/kasan.txt
+++ b/Documentation/kasan.txt
@@ -9,7 +9,7 @@ a fast and comprehensive solution for finding use-after-free and out-of-bounds
bugs.
KASan uses compile-time instrumentation for checking every memory access,
-therefore you will need a certain version of GCC >= 4.9.2
+therefore you will need a certain version of GCC > 4.9.2
Currently KASan is supported only for x86_64 architecture and requires that the
kernel be built with the SLUB allocator.
diff --git a/arch/x86/kernel/module.c b/arch/x86/kernel/module.c
index 2ce4a9a..5892e83 100644
--- a/arch/x86/kernel/module.c
+++ b/arch/x86/kernel/module.c
@@ -24,6 +24,7 @@
#include <linux/fs.h>
#include <linux/string.h>
#include <linux/kernel.h>
+#include <linux/kasan.h>
#include <linux/bug.h>
#include <linux/mm.h>
#include <linux/gfp.h>
@@ -45,11 +46,18 @@ do { \
void *module_alloc(unsigned long size)
{
+ void *p;
+
if (PAGE_ALIGN(size) > MODULES_LEN)
return NULL;
- return __vmalloc_node_range(size, 1, MODULES_VADDR, MODULES_END,
+ p = __vmalloc_node_range(size, MODULE_ALIGN, MODULES_VADDR, MODULES_END,
GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL_EXEC,
- 0, NUMA_NO_NODE, __builtin_return_address(0));
+ 0, NUMA_NO_NODE, __builtin_return_address(0));
+ if (p && (kasan_module_alloc(p, size) < 0)) {
+ vfree(p);
+ return NULL;
+ }
+ return p;
}
#ifdef CONFIG_X86_32
diff --git a/arch/x86/mm/kasan_init_64.c b/arch/x86/mm/kasan_init_64.c
index a0c0dcc..7620537 100644
--- a/arch/x86/mm/kasan_init_64.c
+++ b/arch/x86/mm/kasan_init_64.c
@@ -194,9 +194,9 @@ void __init kasan_init(void)
vmemmap_populate((unsigned long)kasan_mem_to_shadow(_stext),
(unsigned long)kasan_mem_to_shadow(_end),
- NUMA_NO_NODE);
+ 0);
- populate_zero_shadow(kasan_mem_to_shadow((void *)MODULES_VADDR),
+ populate_zero_shadow(kasan_mem_to_shadow((void *)MODULES_END),
(void *)KASAN_SHADOW_END);
memset(kasan_zero_page, 0, PAGE_SIZE);
diff --git a/include/linux/kasan.h b/include/linux/kasan.h
index d5310ee..72ba725 100644
--- a/include/linux/kasan.h
+++ b/include/linux/kasan.h
@@ -49,8 +49,15 @@ void kasan_krealloc(const void *object, size_t new_size);
void kasan_slab_alloc(struct kmem_cache *s, void *object);
void kasan_slab_free(struct kmem_cache *s, void *object);
+#define MODULE_ALIGN (PAGE_SIZE << KASAN_SHADOW_SCALE_SHIFT)
+
+int kasan_module_alloc(void *addr, size_t size);
+void kasan_module_free(void *addr);
+
#else /* CONFIG_KASAN */
+#define MODULE_ALIGN 1
+
static inline void kasan_unpoison_shadow(const void *address, size_t size) {}
static inline void kasan_enable_current(void) {}
@@ -74,6 +81,9 @@ static inline void kasan_krealloc(const void *object, size_t new_size) {}
static inline void kasan_slab_alloc(struct kmem_cache *s, void *object) {}
static inline void kasan_slab_free(struct kmem_cache *s, void *object) {}
+static inline int kasan_module_alloc(void *addr, size_t size) { return 0; }
+static inline void kasan_module_free(void *addr) {}
+
#endif /* CONFIG_KASAN */
#endif /* LINUX_KASAN_H */
diff --git a/kernel/module.c b/kernel/module.c
index d600158..eee276c 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -57,6 +57,7 @@
#include <linux/async.h>
#include <linux/percpu.h>
#include <linux/kmemleak.h>
+#include <linux/kasan.h>
#include <linux/jump_label.h>
#include <linux/pfn.h>
#include <linux/bsearch.h>
@@ -1904,6 +1905,7 @@ static void unset_module_init_ro_nx(struct module *mod) { }
void __weak module_free(struct module *mod, void *module_region)
{
vfree(module_region);
+ kasan_module_free(module_region);
}
void __weak module_arch_cleanup(struct module *mod)
diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan
index 4d47d87..4fecaedc 100644
--- a/lib/Kconfig.kasan
+++ b/lib/Kconfig.kasan
@@ -6,6 +6,7 @@ if HAVE_ARCH_KASAN
config KASAN
bool "KASan: runtime memory debugger"
depends on SLUB_DEBUG
+ select CONSTRUCTORS
help
Enables kernel address sanitizer - runtime memory debugger,
designed to find out-of-bounds accesses and use-after-free bugs.
diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c
index 799c52b..78fee63 100644
--- a/mm/kasan/kasan.c
+++ b/mm/kasan/kasan.c
@@ -22,6 +22,7 @@
#include <linux/memblock.h>
#include <linux/memory.h>
#include <linux/mm.h>
+#include <linux/module.h>
#include <linux/printk.h>
#include <linux/sched.h>
#include <linux/slab.h>
@@ -395,6 +396,57 @@ void kasan_kfree_large(const void *ptr)
KASAN_FREE_PAGE);
}
+int kasan_module_alloc(void *addr, size_t size)
+{
+ void *ret;
+ size_t shadow_size;
+ unsigned long shadow_start;
+
+ shadow_start = (unsigned long)kasan_mem_to_shadow(addr);
+ shadow_size = round_up(size >> KASAN_SHADOW_SCALE_SHIFT,
+ PAGE_SIZE);
+
+ if (WARN_ON(!PAGE_ALIGNED(shadow_start)))
+ return -EINVAL;
+
+ ret = __vmalloc_node_range(shadow_size, 1, shadow_start,
+ shadow_start + shadow_size,
+ GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
+ PAGE_KERNEL, VM_NO_GUARD, NUMA_NO_NODE,
+ __builtin_return_address(0));
+ return ret ? 0 : -ENOMEM;
+}
+
+void kasan_module_free(void *addr)
+{
+ vfree(kasan_mem_to_shadow(addr));
+}
+
+static void register_global(struct kasan_global *global)
+{
+ size_t aligned_size = round_up(global->size, KASAN_SHADOW_SCALE_SIZE);
+
+ kasan_unpoison_shadow(global->beg, global->size);
+
+ kasan_poison_shadow(global->beg + aligned_size,
+ global->size_with_redzone - aligned_size,
+ KASAN_GLOBAL_REDZONE);
+}
+
+void __asan_register_globals(struct kasan_global *globals, size_t size)
+{
+ int i;
+
+ for (i = 0; i < size; i++)
+ register_global(&globals[i]);
+}
+EXPORT_SYMBOL(__asan_register_globals);
+
+void __asan_unregister_globals(struct kasan_global *globals, size_t size)
+{
+}
+EXPORT_SYMBOL(__asan_unregister_globals);
+
#define DEFINE_ASAN_LOAD_STORE(size) \
void __asan_load##size(unsigned long addr) \
{ \
diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
index 1fcc1d8..4986b0a 100644
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h
@@ -11,6 +11,7 @@
#define KASAN_PAGE_REDZONE 0xFE /* redzone for kmalloc_large allocations */
#define KASAN_KMALLOC_REDZONE 0xFC /* redzone inside slub object */
#define KASAN_KMALLOC_FREE 0xFB /* object was freed (kmem_cache_free/kfree) */
+#define KASAN_GLOBAL_REDZONE 0xFA /* redzone for global variable */
/*
* Stack redzone shadow values
@@ -21,6 +22,10 @@
#define KASAN_STACK_RIGHT 0xF3
#define KASAN_STACK_PARTIAL 0xF4
+/* Don't break randconfig/all*config builds */
+#ifndef KASAN_ABI_VERSION
+#define KASAN_ABI_VERSION 1
+#endif
struct kasan_access_info {
const void *access_addr;
@@ -30,6 +35,26 @@ struct kasan_access_info {
unsigned long ip;
};
+/* The layout of struct dictated by compiler */
+struct kasan_source_location {
+ const char *filename;
+ int line_no;
+ int column_no;
+};
+
+/* The layout of struct dictated by compiler */
+struct kasan_global {
+ const void *beg; /* Address of the beginning of the global variable. */
+ size_t size; /* Size of the global variable. */
+ size_t size_with_redzone; /* Size of the variable + size of the red zone. 32 bytes aligned */
+ const void *name;
+ const void *module_name; /* Name of the module where the global variable is declared. */
+ unsigned long has_dynamic_init; /* This needed for C++ */
+#if KASAN_ABI_VERSION >= 4
+ struct kasan_source_location *location;
+#endif
+};
+
void kasan_report_error(struct kasan_access_info *info);
void kasan_report_user_access(struct kasan_access_info *info);
diff --git a/mm/kasan/report.c b/mm/kasan/report.c
index 866732e..680ceed 100644
--- a/mm/kasan/report.c
+++ b/mm/kasan/report.c
@@ -23,6 +23,8 @@
#include <linux/types.h>
#include <linux/kasan.h>
+#include <asm/sections.h>
+
#include "kasan.h"
#include "../slab.h"
@@ -61,6 +63,7 @@ static void print_error_description(struct kasan_access_info *info)
break;
case KASAN_PAGE_REDZONE:
case KASAN_KMALLOC_REDZONE:
+ case KASAN_GLOBAL_REDZONE:
case 0 ... KASAN_SHADOW_SCALE_SIZE - 1:
bug_type = "out of bounds access";
break;
@@ -80,6 +83,20 @@ static void print_error_description(struct kasan_access_info *info)
info->access_size, current->comm, task_pid_nr(current));
}
+static inline bool kernel_or_module_addr(const void *addr)
+{
+ return (addr >= (void *)_stext && addr < (void *)_end)
+ || (addr >= (void *)MODULES_VADDR
+ && addr < (void *)MODULES_END);
+}
+
+static inline bool init_task_stack_addr(const void *addr)
+{
+ return addr >= (void *)&init_thread_union.stack &&
+ (addr <= (void *)&init_thread_union.stack +
+ sizeof(init_thread_union.stack));
+}
+
static void print_address_description(struct kasan_access_info *info)
{
const void *addr = info->access_addr;
@@ -107,6 +124,11 @@ static void print_address_description(struct kasan_access_info *info)
dump_page(page, "kasan: bad access detected");
}
+ if (kernel_or_module_addr(addr)) {
+ if (!init_task_stack_addr(addr))
+ pr_err("Address belongs to variable %pS\n", addr);
+ }
+
dump_stack();
}
diff --git a/scripts/Makefile.kasan b/scripts/Makefile.kasan
index 2163b8c..631619b 100644
--- a/scripts/Makefile.kasan
+++ b/scripts/Makefile.kasan
@@ -9,7 +9,7 @@ CFLAGS_KASAN_MINIMAL := -fsanitize=kernel-address
CFLAGS_KASAN := $(call cc-option, -fsanitize=kernel-address \
-fasan-shadow-offset=$(CONFIG_KASAN_SHADOW_OFFSET) \
- --param asan-stack=1 \
+ --param asan-stack=1 --param asan-globals=1 \
--param asan-instrumentation-with-call-threshold=$(call_threshold))
ifeq ($(call cc-option, $(CFLAGS_KASAN_MINIMAL) -Werror),)
--
2.4.6
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