[PATCH V2 00/10] KASan ppc64 support

[PATCH V2 00/10] KASan ppc64 support

[Aneesh Kumar K.V]

Hi,

This patchset implements kernel address sanitizer for ppc64.
Since ppc64 virtual address range is divided into different regions,
we can't have one contigous area for the kasan shadow range. Hence
we don't support the INLINE kasan instrumentation. With Outline
instrumentation, we override the shadow_to_mem and mem_to_shadow
callbacks, so that we map only the kernel linear range (ie,
region with ID 0xc). For region with ID 0xd and 0xf (vmalloc
and vmemmap ) we return the address of the zero page. This
works because kasan doesn't track both vmemmap and vmalloc address.

Known issues:
* Kasan is not yet enabled for arch/powerpc/kvm
* kexec hang
* outline stack and global support

Once we fix the kexec hang, we can look at merging ppc64 patch.
IMHO kasan changes can be reviewed/merged earlier 

Aneesh Kumar K.V (10):
  powerpc/mm: Add virt_to_pfn and use this instead of opencoding
  kasan: MODULE_VADDR is not available on all archs
  kasan: Rename kasan_enabled to kasan_report_enabled
  kasan: Don't use kasan shadow pointer in generic functions
  kasan: Enable arch to hook into kasan callbacks.
  kasan: Allow arch to overrride kasan shadow offsets
  kasan: Make INLINE KASan support arch selectable
  kasan: Update feature support file
  kasan: Prevent deadlock in kasan reporting
  powerpc/mm: kasan: Add kasan support for ppc64

 .../debug/KASAN/KASAN_INLINE/arch-support.txt      | 40 ++++++++++++
 .../KASAN/{ => KASAN_OUTLINE}/arch-support.txt     |  0
 arch/powerpc/include/asm/kasan.h                   | 74 ++++++++++++++++++++++
 arch/powerpc/include/asm/page.h                    |  5 +-
 arch/powerpc/include/asm/pgtable-ppc64.h           |  1 +
 arch/powerpc/include/asm/ppc_asm.h                 | 10 +++
 arch/powerpc/include/asm/string.h                  | 13 ++++
 arch/powerpc/kernel/Makefile                       |  5 ++
 arch/powerpc/kernel/prom_init_check.sh             |  2 +-
 arch/powerpc/kernel/setup_64.c                     |  3 +
 arch/powerpc/kvm/Makefile                          |  1 +
 arch/powerpc/lib/mem_64.S                          |  6 +-
 arch/powerpc/lib/memcpy_64.S                       |  3 +-
 arch/powerpc/lib/ppc_ksyms.c                       | 10 +++
 arch/powerpc/mm/Makefile                           |  7 ++
 arch/powerpc/mm/kasan_init.c                       | 44 +++++++++++++
 arch/powerpc/mm/slb_low.S                          |  4 ++
 arch/powerpc/platforms/Kconfig.cputype             |  1 +
 arch/x86/Kconfig                                   |  1 +
 include/linux/kasan.h                              |  3 +
 lib/Kconfig.kasan                                  |  2 +
 mm/kasan/kasan.c                                   |  9 +++
 mm/kasan/kasan.h                                   | 20 +++++-
 mm/kasan/report.c                                  | 29 ++++++---
 scripts/Makefile.kasan                             | 28 ++++----
 25 files changed, 290 insertions(+), 31 deletions(-)
 create mode 100644 Documentation/features/debug/KASAN/KASAN_INLINE/arch-support.txt
 rename Documentation/features/debug/KASAN/{ => KASAN_OUTLINE}/arch-support.txt (100%)
 create mode 100644 arch/powerpc/include/asm/kasan.h
 create mode 100644 arch/powerpc/mm/kasan_init.c

-- 
2.5.0

[PATCH V2 01/10] powerpc/mm: Add virt_to_pfn and use this instead of opencoding

[Aneesh Kumar K.V]

This add helper virt_to_pfn and remove the opencoded usage of the
same.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---
 arch/powerpc/include/asm/page.h | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/include/asm/page.h b/arch/powerpc/include/asm/page.h
index 71294a6e976e..168ca67e39b3 100644
--- a/arch/powerpc/include/asm/page.h
+++ b/arch/powerpc/include/asm/page.h
@@ -127,9 +127,10 @@ extern long long virt_phys_offset;
 #define pfn_valid(pfn)		((pfn) >= ARCH_PFN_OFFSET && (pfn) < max_mapnr)
 #endif
 
-#define virt_to_page(kaddr)	pfn_to_page(__pa(kaddr) >> PAGE_SHIFT)
+#define virt_to_pfn(kaddr)	(__pa(kaddr) >> PAGE_SHIFT)
+#define virt_to_page(kaddr)	pfn_to_page(virt_to_pfn(kaddr))
 #define pfn_to_kaddr(pfn)	__va((pfn) << PAGE_SHIFT)
-#define virt_addr_valid(kaddr)	pfn_valid(__pa(kaddr) >> PAGE_SHIFT)
+#define virt_addr_valid(kaddr)	pfn_valid(virt_to_pfn(kaddr))
 
 /*
  * On Book-E parts we need __va to parse the device tree and we can't
-- 
2.5.0

[PATCH V2 02/10] kasan: MODULE_VADDR is not available on all archs

[Aneesh Kumar K.V]

Conditionalize the check using #ifdef

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---
 mm/kasan/report.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/mm/kasan/report.c b/mm/kasan/report.c
index e07c94fbd0ac..71ce7548d914 100644
--- a/mm/kasan/report.c
+++ b/mm/kasan/report.c
@@ -85,9 +85,14 @@ static void print_error_description(struct kasan_access_info *info)
 
 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);
+	if (addr >= (void *)_stext && addr < (void *)_end)
+		return true;
+#if defined(CONFIG_MODULES) && defined(MODULES_VADDR)
+	if (addr >= (void *)MODULES_VADDR
+			&& addr < (void *)MODULES_END)
+		return true;
+#endif
+	return false;
 }
 
 static inline bool init_task_stack_addr(const void *addr)
-- 
2.5.0

[PATCH V2 03/10] kasan: Rename kasan_enabled to kasan_report_enabled

[Aneesh Kumar K.V]

The function only disable/enable reporting. In the later patch
we will be adding a kasan early enable/disable. Rename kasan_enabled
to properly reflect its function.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---
 mm/kasan/kasan.h  | 2 +-
 mm/kasan/report.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
index c242adf6bc85..a6b46cc94907 100644
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h
@@ -63,7 +63,7 @@ static inline const void *kasan_shadow_to_mem(const void *shadow_addr)
 		<< KASAN_SHADOW_SCALE_SHIFT);
 }
 
-static inline bool kasan_enabled(void)
+static inline bool kasan_report_enabled(void)
 {
 	return !current->kasan_depth;
 }
diff --git a/mm/kasan/report.c b/mm/kasan/report.c
index 71ce7548d914..d19d01823a68 100644
--- a/mm/kasan/report.c
+++ b/mm/kasan/report.c
@@ -225,7 +225,7 @@ void kasan_report(unsigned long addr, size_t size,
 {
 	struct kasan_access_info info;
 
-	if (likely(!kasan_enabled()))
+	if (likely(!kasan_report_enabled()))
 		return;
 
 	info.access_addr = (void *)addr;
-- 
2.5.0

[PATCH V2 04/10] kasan: Don't use kasan shadow pointer in generic functions

[Aneesh Kumar K.V]

We can't use generic functions like print_hex_dump to access kasan
shadow region. This require us to setup another kasan shadow region
for the address passed (kasan shadow address). Most architecture won't
be able to do that. Hence remove dumping kasan shadow region dump. If
we really want to do this we will have to have a kasan internal implemen
tation of print_hex_dump for which we will disable address sanitizer
operation.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---
 mm/kasan/report.c | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/mm/kasan/report.c b/mm/kasan/report.c
index d19d01823a68..79fbc5d14bd2 100644
--- a/mm/kasan/report.c
+++ b/mm/kasan/report.c
@@ -170,12 +170,6 @@ static void print_shadow_for_address(const void *addr)
 		snprintf(buffer, sizeof(buffer),
 			(i == 0) ? ">%p: " : " %p: ", kaddr);
 
-		kasan_disable_current();
-		print_hex_dump(KERN_ERR, buffer,
-			DUMP_PREFIX_NONE, SHADOW_BYTES_PER_ROW, 1,
-			shadow_row, SHADOW_BYTES_PER_ROW, 0);
-		kasan_enable_current();
-
 		if (row_is_guilty(shadow_row, shadow))
 			pr_err("%*c\n",
 				shadow_pointer_offset(shadow_row, shadow),
-- 
2.5.0

[PATCH V2 05/10] kasan: Enable arch to hook into kasan callbacks.

[Aneesh Kumar K.V]

We add enable/disable callbacks in this patch which architecture
can implemement. We will use this in the later patches for architecture
like ppc64, that cannot have early zero page kasan shadow region for the
entire virtual address space. Such architectures also cannot use
inline kasan support.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---
 mm/kasan/kasan.c |  9 +++++++++
 mm/kasan/kasan.h | 15 +++++++++++++++
 2 files changed, 24 insertions(+)

diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c
index 7b28e9cdf1c7..e4d33afd0eaf 100644
--- a/mm/kasan/kasan.c
+++ b/mm/kasan/kasan.c
@@ -43,6 +43,9 @@ static void kasan_poison_shadow(const void *address, size_t size, u8 value)
 {
 	void *shadow_start, *shadow_end;
 
+	if (!kasan_enabled())
+		return;
+
 	shadow_start = kasan_mem_to_shadow(address);
 	shadow_end = kasan_mem_to_shadow(address + size);
 
@@ -51,6 +54,9 @@ static void kasan_poison_shadow(const void *address, size_t size, u8 value)
 
 void kasan_unpoison_shadow(const void *address, size_t size)
 {
+	if (!kasan_enabled())
+		return;
+
 	kasan_poison_shadow(address, size, 0);
 
 	if (size & KASAN_SHADOW_MASK) {
@@ -238,6 +244,9 @@ static __always_inline void check_memory_region(unsigned long addr,
 {
 	struct kasan_access_info info;
 
+	if (!kasan_enabled())
+		return;
+
 	if (unlikely(size == 0))
 		return;
 
diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
index a6b46cc94907..deb547d5a916 100644
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h
@@ -68,6 +68,21 @@ static inline bool kasan_report_enabled(void)
 	return !current->kasan_depth;
 }
 
+#ifndef kasan_enabled
+/*
+ * Some archs may want to disable kasan callbacks.
+ */
+static inline bool kasan_enabled(void)
+{
+	return true;
+}
+#define kasan_enabled kasan_enabled
+#else
+#ifdef CONFIG_KASAN_INLINE
+#error "Kasan inline support cannot work with KASAN arch hooks"
+#endif
+#endif
+
 void kasan_report(unsigned long addr, size_t size,
 		bool is_write, unsigned long ip);
 
-- 
2.5.0

[PATCH V2 06/10] kasan: Allow arch to overrride kasan shadow offsets

[Aneesh Kumar K.V]

Some archs may want to provide kasan shadow memory as a constant
offset from the address. Such arch even though cannot use inline kasan
support, they can work with outofline kasan support.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---
 include/linux/kasan.h | 3 +++
 mm/kasan/kasan.h      | 3 +++
 2 files changed, 6 insertions(+)

diff --git a/include/linux/kasan.h b/include/linux/kasan.h
index 5486d777b706..e458ca64cdaf 100644
--- a/include/linux/kasan.h
+++ b/include/linux/kasan.h
@@ -15,11 +15,14 @@ struct vm_struct;
 #include <asm/kasan.h>
 #include <linux/sched.h>
 
+#ifndef kasan_mem_to_shadow
 static inline void *kasan_mem_to_shadow(const void *addr)
 {
 	return (void *)((unsigned long)addr >> KASAN_SHADOW_SCALE_SHIFT)
 		+ KASAN_SHADOW_OFFSET;
 }
+#define kasan_mem_to_shadow kasan_mem_to_shadow
+#endif
 
 /* Enable reporting bugs after kasan_disable_current() */
 static inline void kasan_enable_current(void)
diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
index deb547d5a916..c0686f2b1224 100644
--- a/mm/kasan/kasan.h
+++ b/mm/kasan/kasan.h
@@ -57,11 +57,14 @@ struct kasan_global {
 void kasan_report_error(struct kasan_access_info *info);
 void kasan_report_user_access(struct kasan_access_info *info);
 
+#ifndef kasan_shadow_to_mem
 static inline const void *kasan_shadow_to_mem(const void *shadow_addr)
 {
 	return (void *)(((unsigned long)shadow_addr - KASAN_SHADOW_OFFSET)
 		<< KASAN_SHADOW_SCALE_SHIFT);
 }
+#define kasan_shadow_to_mem kasan_shadow_to_mem
+#endif
 
 static inline bool kasan_report_enabled(void)
 {
-- 
2.5.0

[PATCH V2 07/10] kasan: Make INLINE KASan support arch selectable

[Aneesh Kumar K.V]

Some of the archs, may find it difficult to support inline KASan
mode. Add HAVE_ARCH_KASAN_INLINE so that we can disable inline
support at config time.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---
 arch/x86/Kconfig       |  1 +
 lib/Kconfig.kasan      |  2 ++
 scripts/Makefile.kasan | 28 ++++++++++++++--------------
 3 files changed, 17 insertions(+), 14 deletions(-)

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index b3a1a5d77d92..4416f80580fb 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -78,6 +78,7 @@ config X86
 	select HAVE_ARCH_HUGE_VMAP		if X86_64 || X86_PAE
 	select HAVE_ARCH_JUMP_LABEL
 	select HAVE_ARCH_KASAN			if X86_64 && SPARSEMEM_VMEMMAP
+	select HAVE_ARCH_KASAN_INLINE			if X86_64 && SPARSEMEM_VMEMMAP
 	select HAVE_ARCH_KGDB
 	select HAVE_ARCH_KMEMCHECK
 	select HAVE_ARCH_SECCOMP_FILTER
diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan
index 39f24d6721e5..e9d1bb1175b8 100644
--- a/lib/Kconfig.kasan
+++ b/lib/Kconfig.kasan
@@ -32,6 +32,7 @@ config KASAN_OUTLINE
 	  however it doesn't bloat size of kernel's .text section so
 	  much as inline does.
 
+if HAVE_ARCH_KASAN_INLINE
 config KASAN_INLINE
 	bool "Inline instrumentation"
 	help
@@ -40,6 +41,7 @@ config KASAN_INLINE
 	  it gives about x2 boost over outline instrumentation), but
 	  make kernel's .text size much bigger.
 	  This requires a gcc version of 5.0 or later.
+endif
 
 endchoice
 
diff --git a/scripts/Makefile.kasan b/scripts/Makefile.kasan
index 3f874d24234f..c1c06e9e107a 100644
--- a/scripts/Makefile.kasan
+++ b/scripts/Makefile.kasan
@@ -1,29 +1,29 @@
 ifdef CONFIG_KASAN
-ifdef CONFIG_KASAN_INLINE
-	call_threshold := 10000
-else
-	call_threshold := 0
-endif
-
-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-globals=1 \
-		--param asan-instrumentation-with-call-threshold=$(call_threshold))
-
-ifeq ($(call cc-option, $(CFLAGS_KASAN_MINIMAL) -Werror),)
+                   --param asan-instrumentation-with-call-threshold=0)
+ifeq ($(CFLAGS_KASAN),)
    ifneq ($(CONFIG_COMPILE_TEST),y)
         $(warning Cannot use CONFIG_KASAN: \
             -fsanitize=kernel-address is not supported by compiler)
    endif
 else
-    ifeq ($(CFLAGS_KASAN),)
+
+   ifdef CONFIG_KASAN_INLINE
+   CFLAGS_KASAN_INLINE := $(call cc-option, -fsanitize=kernel-address \
+                        -fasan-shadow-offset=$(CONFIG_KASAN_SHADOW_OFFSET) \
+                        --param asan-stack=1 --param asan-globals=1 \
+                        --param asan-instrumentation-with-call-threshold=10000)
+
+    ifeq ($(CFLAGS_KASAN_INLINE),)
         ifneq ($(CONFIG_COMPILE_TEST),y)
             $(warning CONFIG_KASAN: compiler does not support all options.\
                 Trying minimal configuration)
         endif
-        CFLAGS_KASAN := $(CFLAGS_KASAN_MINIMAL)
+    else
+        CFLAGS_KASAN := $(CFLAGS_KASAN_INLINE)
     endif
+    endif
+
 endif
 endif
-- 
2.5.0

[PATCH V2 08/10] kasan: Update feature support file

[Aneesh Kumar K.V]

Now that we have two features KASAN and KASAN_INLINE, add new feature
support file for the same.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---
 .../debug/KASAN/KASAN_INLINE/arch-support.txt      | 40 ++++++++++++++++++++++
 .../KASAN/{ => KASAN_OUTLINE}/arch-support.txt     |  0
 2 files changed, 40 insertions(+)
 create mode 100644 Documentation/features/debug/KASAN/KASAN_INLINE/arch-support.txt
 rename Documentation/features/debug/KASAN/{ => KASAN_OUTLINE}/arch-support.txt (100%)

diff --git a/Documentation/features/debug/KASAN/KASAN_INLINE/arch-support.txt b/Documentation/features/debug/KASAN/KASAN_INLINE/arch-support.txt
new file mode 100644
index 000000000000..834818fba910
--- /dev/null
+++ b/Documentation/features/debug/KASAN/KASAN_INLINE/arch-support.txt
@@ -0,0 +1,40 @@
+#
+# Feature name:          KASAN
+#         Kconfig:       HAVE_ARCH_KASAN_INLINE
+#         description:   arch supports the KASAN runtime memory checker
+#
+    -----------------------
+    |         arch |status|
+    -----------------------
+    |       alpha: | TODO |
+    |         arc: | TODO |
+    |         arm: | TODO |
+    |       arm64: | TODO |
+    |       avr32: | TODO |
+    |    blackfin: | TODO |
+    |         c6x: | TODO |
+    |        cris: | TODO |
+    |         frv: | TODO |
+    |       h8300: | TODO |
+    |     hexagon: | TODO |
+    |        ia64: | TODO |
+    |        m32r: | TODO |
+    |        m68k: | TODO |
+    |       metag: | TODO |
+    |  microblaze: | TODO |
+    |        mips: | TODO |
+    |     mn10300: | TODO |
+    |       nios2: | TODO |
+    |    openrisc: | TODO |
+    |      parisc: | TODO |
+    |     powerpc: | TODO |
+    |        s390: | TODO |
+    |       score: | TODO |
+    |          sh: | TODO |
+    |       sparc: | TODO |
+    |        tile: | TODO |
+    |          um: | TODO |
+    |   unicore32: | TODO |
+    |         x86: |  ok  |
+    |      xtensa: | TODO |
+    -----------------------
diff --git a/Documentation/features/debug/KASAN/arch-support.txt b/Documentation/features/debug/KASAN/KASAN_OUTLINE/arch-support.txt
similarity index 100%
rename from Documentation/features/debug/KASAN/arch-support.txt
rename to Documentation/features/debug/KASAN/KASAN_OUTLINE/arch-support.txt
-- 
2.5.0