[RFC PATCH 5/5] powerpc: KASAN for 64bit Book3E
Daniel Axtens
dja at axtens.net
Fri Feb 15 11:04:41 AEDT 2019
Wire up KASAN. Only outline instrumentation is supported.
The KASAN shadow area is mapped into vmemmap space:
0x8000 0400 0000 0000 to 0x8000 0600 0000 0000.
To do this we require that vmemmap be disabled. (This is the default
in the kernel config that QorIQ provides for the machine in their
SDK anyway - they use flat memory.)
Only the kernel linear mapping (0xc000...) is checked. The vmalloc and
ioremap areas (also in 0x800...) are all mapped to a zero page. As
with the Book3S hash series, this requires overriding the memory <->
shadow mapping.
Also, as with both previous 64-bit series, early instrumentation is not
supported. It would allow us to drop the check_return_arch_not_ready()
hook in the KASAN core, but it's tricky to get it set up early enough:
we need it setup before the first call to instrumented code like printk().
Perhaps in the future.
Only KASAN_MINIMAL works.
Lightly tested on e6500. KVM, kexec and xmon have not been tested.
The test_kasan module fires warnings as expected, except for the
following tests:
- Expected/by design:
kasan test: memcg_accounted_kmem_cache allocate memcg accounted object
- Due to only supporting KASAN_MINIMAL:
kasan test: kasan_stack_oob out-of-bounds on stack
kasan test: kasan_global_oob out-of-bounds global variable
kasan test: kasan_alloca_oob_left out-of-bounds to left on alloca
kasan test: kasan_alloca_oob_right out-of-bounds to right on alloca
kasan test: use_after_scope_test use-after-scope on int
kasan test: use_after_scope_test use-after-scope on array
Thanks to those who have done the heavy lifting over the past several years:
- Christophe's 32 bit series: https://lists.ozlabs.org/pipermail/linuxppc-dev/2019-February/185379.html
- Aneesh's Book3S hash series: https://lwn.net/Articles/655642/
- Balbir's Book3S radix series: https://patchwork.ozlabs.org/patch/795211/
Cc: Christophe Leroy <christophe.leroy at c-s.fr>
Cc: Aneesh Kumar K.V <aneesh.kumar at linux.vnet.ibm.com>
Cc: Balbir Singh <bsingharora at gmail.com>
Signed-off-by: Daniel Axtens <dja at axtens.net>
---
While useful if you have a book3e device, this is mostly intended
as a warm-up exercise for reviving Aneesh's series for book3s hash.
In particular, changes to the kasan core are going to be required
for hash and radix as well.
---
arch/powerpc/Kconfig | 1 +
arch/powerpc/Makefile | 2 +
arch/powerpc/include/asm/kasan.h | 77 ++++++++++++++++++--
arch/powerpc/include/asm/ppc_asm.h | 7 ++
arch/powerpc/include/asm/string.h | 7 +-
arch/powerpc/lib/mem_64.S | 6 +-
arch/powerpc/lib/memcmp_64.S | 5 +-
arch/powerpc/lib/memcpy_64.S | 3 +-
arch/powerpc/lib/string.S | 15 ++--
arch/powerpc/mm/Makefile | 2 +
arch/powerpc/mm/kasan/Makefile | 1 +
arch/powerpc/mm/kasan/kasan_init_book3e_64.c | 53 ++++++++++++++
arch/powerpc/purgatory/Makefile | 3 +
arch/powerpc/xmon/Makefile | 1 +
14 files changed, 164 insertions(+), 19 deletions(-)
create mode 100644 arch/powerpc/mm/kasan/kasan_init_book3e_64.c
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 850b06def84f..2c7c20d52778 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -176,6 +176,7 @@ config PPC
select HAVE_ARCH_AUDITSYSCALL
select HAVE_ARCH_JUMP_LABEL
select HAVE_ARCH_KASAN if PPC32
+ select HAVE_ARCH_KASAN if PPC_BOOK3E_64 && !SPARSEMEM_VMEMMAP
select HAVE_ARCH_KGDB
select HAVE_ARCH_MMAP_RND_BITS
select HAVE_ARCH_MMAP_RND_COMPAT_BITS if COMPAT
diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
index f0738099e31e..21c2dadf0315 100644
--- a/arch/powerpc/Makefile
+++ b/arch/powerpc/Makefile
@@ -428,11 +428,13 @@ endif
endif
ifdef CONFIG_KASAN
+ifdef CONFIG_PPC32
prepare: kasan_prepare
kasan_prepare: prepare0
$(eval KASAN_SHADOW_OFFSET = $(shell awk '{if ($$2 == "KASAN_SHADOW_OFFSET") print $$3;}' include/generated/asm-offsets.h))
endif
+endif
# Check toolchain versions:
# - gcc-4.6 is the minimum kernel-wide version so nothing required.
diff --git a/arch/powerpc/include/asm/kasan.h b/arch/powerpc/include/asm/kasan.h
index 5d0088429b62..c2f6f05dfaa3 100644
--- a/arch/powerpc/include/asm/kasan.h
+++ b/arch/powerpc/include/asm/kasan.h
@@ -5,20 +5,85 @@
#ifndef __ASSEMBLY__
#include <asm/page.h>
+#include <asm/pgtable.h>
#include <asm/pgtable-types.h>
-#include <asm/fixmap.h>
#define KASAN_SHADOW_SCALE_SHIFT 3
-#define KASAN_SHADOW_SIZE ((~0UL - PAGE_OFFSET + 1) >> KASAN_SHADOW_SCALE_SHIFT)
-#define KASAN_SHADOW_START (ALIGN_DOWN(FIXADDR_START - KASAN_SHADOW_SIZE, \
- PGDIR_SIZE))
-#define KASAN_SHADOW_END (KASAN_SHADOW_START + KASAN_SHADOW_SIZE)
#define KASAN_SHADOW_OFFSET (KASAN_SHADOW_START - \
(PAGE_OFFSET >> KASAN_SHADOW_SCALE_SHIFT))
+#define KASAN_SHADOW_END (KASAN_SHADOW_START + KASAN_SHADOW_SIZE)
+
+
+#ifdef CONFIG_PPC32
+#include <asm/fixmap.h>
+#define KASAN_SHADOW_START (ALIGN_DOWN(FIXADDR_START - KASAN_SHADOW_SIZE, \
+ PGDIR_SIZE))
+#define KASAN_SHADOW_SIZE ((~0UL - PAGE_OFFSET + 1) >> KASAN_SHADOW_SCALE_SHIFT)
void kasan_early_init(void);
+
+#endif /* CONFIG_PPC32 */
+
+#ifdef CONFIG_PPC_BOOK3E_64
+#define KASAN_SHADOW_START VMEMMAP_BASE
+#define KASAN_SHADOW_SIZE (KERN_VIRT_SIZE >> KASAN_SHADOW_SCALE_SHIFT)
+
+extern struct static_key_false powerpc_kasan_enabled_key;
+#define check_return_arch_not_ready() \
+ do { \
+ if (!static_branch_likely(&powerpc_kasan_enabled_key)) \
+ return; \
+ } while (0)
+
+extern unsigned char kasan_zero_page[PAGE_SIZE];
+static inline void *kasan_mem_to_shadow_book3e(const void *addr)
+{
+ if ((unsigned long)addr >= KERN_VIRT_START &&
+ (unsigned long)addr < (KERN_VIRT_START + KERN_VIRT_SIZE)) {
+ return (void *)kasan_zero_page;
+ }
+
+ return (void *)((unsigned long)addr >> KASAN_SHADOW_SCALE_SHIFT)
+ + KASAN_SHADOW_OFFSET;
+}
+#define kasan_mem_to_shadow kasan_mem_to_shadow_book3e
+
+static inline void *kasan_shadow_to_mem_book3e(const void *shadow_addr)
+{
+ /*
+ * We map the entire non-linear virtual mapping onto the zero page so if
+ * we are asked to map the zero page back just pick the beginning of that
+ * area.
+ */
+ if (shadow_addr >= (void *)kasan_zero_page &&
+ shadow_addr < (void *)(kasan_zero_page + PAGE_SIZE)) {
+ return (void *)KERN_VIRT_START;
+ }
+
+ return (void *)(((unsigned long)shadow_addr - KASAN_SHADOW_OFFSET)
+ << KASAN_SHADOW_SCALE_SHIFT);
+}
+#define kasan_shadow_to_mem kasan_shadow_to_mem_book3e
+
+static inline bool kasan_addr_has_shadow_book3e(const void *addr)
+{
+ /*
+ * We want to specifically assert that the addresses in the 0x8000...
+ * region have a shadow, otherwise they are considered by the kasan
+ * core to be wild pointers
+ */
+ if ((unsigned long)addr >= KERN_VIRT_START &&
+ (unsigned long)addr < (KERN_VIRT_START + KERN_VIRT_SIZE)) {
+ return true;
+ }
+ return (addr >= kasan_shadow_to_mem((void *)KASAN_SHADOW_START));
+}
+#define kasan_addr_has_shadow kasan_addr_has_shadow_book3e
+
+#endif /* CONFIG_PPC_BOOK3E_64 */
+
void kasan_init(void);
-#endif
+#endif /* CONFIG_KASAN */
#endif
diff --git a/arch/powerpc/include/asm/ppc_asm.h b/arch/powerpc/include/asm/ppc_asm.h
index dba2c1038363..fd7c9fa9d307 100644
--- a/arch/powerpc/include/asm/ppc_asm.h
+++ b/arch/powerpc/include/asm/ppc_asm.h
@@ -251,10 +251,17 @@ GLUE(.,name):
#define _GLOBAL_TOC(name) _GLOBAL(name)
+#endif /* 32-bit */
+
+/* KASAN helpers */
#define KASAN_OVERRIDE(x, y) \
.weak x; \
.set x, y
+#ifdef CONFIG_KASAN
+#define EXPORT_SYMBOL_NOKASAN(x)
+#else
+#define EXPORT_SYMBOL_NOKASAN(x) EXPORT_SYMBOL(x)
#endif
/*
diff --git a/arch/powerpc/include/asm/string.h b/arch/powerpc/include/asm/string.h
index 64d44d4836b4..e2801d517d57 100644
--- a/arch/powerpc/include/asm/string.h
+++ b/arch/powerpc/include/asm/string.h
@@ -4,13 +4,16 @@
#ifdef __KERNEL__
+#ifndef CONFIG_KASAN
#define __HAVE_ARCH_STRNCPY
#define __HAVE_ARCH_STRNCMP
+#define __HAVE_ARCH_MEMCHR
+#define __HAVE_ARCH_MEMCMP
+#endif
+
#define __HAVE_ARCH_MEMSET
#define __HAVE_ARCH_MEMCPY
#define __HAVE_ARCH_MEMMOVE
-#define __HAVE_ARCH_MEMCMP
-#define __HAVE_ARCH_MEMCHR
#define __HAVE_ARCH_MEMSET16
#define __HAVE_ARCH_MEMCPY_FLUSHCACHE
diff --git a/arch/powerpc/lib/mem_64.S b/arch/powerpc/lib/mem_64.S
index 3c3be02f33b7..3ff4c6b45505 100644
--- a/arch/powerpc/lib/mem_64.S
+++ b/arch/powerpc/lib/mem_64.S
@@ -30,7 +30,8 @@ EXPORT_SYMBOL(__memset16)
EXPORT_SYMBOL(__memset32)
EXPORT_SYMBOL(__memset64)
-_GLOBAL(memset)
+_GLOBAL(__memset)
+KASAN_OVERRIDE(memset, __memset)
neg r0,r3
rlwimi r4,r4,8,16,23
andi. r0,r0,7 /* # bytes to be 8-byte aligned */
@@ -97,7 +98,8 @@ _GLOBAL(memset)
blr
EXPORT_SYMBOL(memset)
-_GLOBAL_TOC(memmove)
+_GLOBAL_TOC(__memmove)
+KASAN_OVERRIDE(memmove, __memmove)
cmplw 0,r3,r4
bgt backwards_memcpy
b memcpy
diff --git a/arch/powerpc/lib/memcmp_64.S b/arch/powerpc/lib/memcmp_64.S
index 844d8e774492..21aee60de2cd 100644
--- a/arch/powerpc/lib/memcmp_64.S
+++ b/arch/powerpc/lib/memcmp_64.S
@@ -102,7 +102,8 @@
* 2) src/dst has different offset to the 8 bytes boundary. The handlers
* are named like .Ldiffoffset_xxxx
*/
-_GLOBAL_TOC(memcmp)
+_GLOBAL_TOC(__memcmp)
+KASAN_OVERRIDE(memcmp, __memcmp)
cmpdi cr1,r5,0
/* Use the short loop if the src/dst addresses are not
@@ -630,4 +631,4 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
b .Lcmp_lt32bytes
#endif
-EXPORT_SYMBOL(memcmp)
+EXPORT_SYMBOL_NOKASAN(memcmp)
diff --git a/arch/powerpc/lib/memcpy_64.S b/arch/powerpc/lib/memcpy_64.S
index 273ea67e60a1..e9092a0e531a 100644
--- a/arch/powerpc/lib/memcpy_64.S
+++ b/arch/powerpc/lib/memcpy_64.S
@@ -18,7 +18,8 @@
#endif
.align 7
-_GLOBAL_TOC(memcpy)
+_GLOBAL_TOC(__memcpy)
+KASAN_OVERRIDE(memcpy, __memcpy)
BEGIN_FTR_SECTION
#ifdef __LITTLE_ENDIAN__
cmpdi cr7,r5,0
diff --git a/arch/powerpc/lib/string.S b/arch/powerpc/lib/string.S
index 4b41970e9ed8..09deaac6e5f1 100644
--- a/arch/powerpc/lib/string.S
+++ b/arch/powerpc/lib/string.S
@@ -16,7 +16,8 @@
/* This clears out any unused part of the destination buffer,
just as the libc version does. -- paulus */
-_GLOBAL(strncpy)
+_GLOBAL(__strncpy)
+KASAN_OVERRIDE(strncpy, __strncpy)
PPC_LCMPI 0,r5,0
beqlr
mtctr r5
@@ -34,9 +35,10 @@ _GLOBAL(strncpy)
2: stbu r0,1(r6) /* clear it out if so */
bdnz 2b
blr
-EXPORT_SYMBOL(strncpy)
+EXPORT_SYMBOL_NOKASAN(strncpy)
-_GLOBAL(strncmp)
+_GLOBAL(__strncmp)
+KASAN_OVERRIDE(strncmp, __strncmp)
PPC_LCMPI 0,r5,0
beq- 2f
mtctr r5
@@ -52,9 +54,10 @@ _GLOBAL(strncmp)
blr
2: li r3,0
blr
-EXPORT_SYMBOL(strncmp)
+EXPORT_SYMBOL_NOKASAN(strncmp)
-_GLOBAL(memchr)
+_GLOBAL(__memchr)
+KASAN_OVERRIDE(memchr, __memchr)
PPC_LCMPI 0,r5,0
beq- 2f
mtctr r5
@@ -66,4 +69,4 @@ _GLOBAL(memchr)
beqlr
2: li r3,0
blr
-EXPORT_SYMBOL(memchr)
+EXPORT_SYMBOL_NOKASAN(memchr)
diff --git a/arch/powerpc/mm/Makefile b/arch/powerpc/mm/Makefile
index 457c0ea2b5e7..d974f7bcb177 100644
--- a/arch/powerpc/mm/Makefile
+++ b/arch/powerpc/mm/Makefile
@@ -7,6 +7,8 @@ ccflags-$(CONFIG_PPC64) := $(NO_MINIMAL_TOC)
CFLAGS_REMOVE_slb.o = $(CC_FLAGS_FTRACE)
+KASAN_SANITIZE_fsl_booke_mmu.o := n
+
obj-y := fault.o mem.o pgtable.o mmap.o \
init_$(BITS).o pgtable_$(BITS).o \
init-common.o mmu_context.o drmem.o
diff --git a/arch/powerpc/mm/kasan/Makefile b/arch/powerpc/mm/kasan/Makefile
index 6577897673dd..f8f164ad8ade 100644
--- a/arch/powerpc/mm/kasan/Makefile
+++ b/arch/powerpc/mm/kasan/Makefile
@@ -3,3 +3,4 @@
KASAN_SANITIZE := n
obj-$(CONFIG_PPC32) += kasan_init_32.o
+obj-$(CONFIG_PPC_BOOK3E_64) += kasan_init_book3e_64.o
diff --git a/arch/powerpc/mm/kasan/kasan_init_book3e_64.c b/arch/powerpc/mm/kasan/kasan_init_book3e_64.c
new file mode 100644
index 000000000000..93b9afcf1020
--- /dev/null
+++ b/arch/powerpc/mm/kasan/kasan_init_book3e_64.c
@@ -0,0 +1,53 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#define DISABLE_BRANCH_PROFILING
+
+#include <linux/kasan.h>
+#include <linux/printk.h>
+#include <linux/memblock.h>
+#include <linux/sched/task.h>
+#include <asm/pgalloc.h>
+
+DEFINE_STATIC_KEY_FALSE(powerpc_kasan_enabled_key);
+EXPORT_SYMBOL(powerpc_kasan_enabled_key);
+unsigned char kasan_zero_page[PAGE_SIZE] __page_aligned_bss;
+
+static void __init kasan_init_region(struct memblock_region *reg)
+{
+ void *start = __va(reg->base);
+ void *end = __va(reg->base + reg->size);
+ unsigned long k_start, k_end, k_cur;
+
+ if (start >= end)
+ return;
+
+ k_start = (unsigned long)kasan_mem_to_shadow(start);
+ k_end = (unsigned long)kasan_mem_to_shadow(end);
+
+ for (k_cur = k_start; k_cur < k_end; k_cur += PAGE_SIZE) {
+ void *va = memblock_alloc(PAGE_SIZE, PAGE_SIZE);
+ map_kernel_page(k_cur, __pa(va), PAGE_KERNEL);
+ }
+ flush_tlb_kernel_range(k_start, k_end);
+}
+
+void __init kasan_init(void)
+{
+ struct memblock_region *reg;
+
+ for_each_memblock(memory, reg)
+ kasan_init_region(reg);
+
+ /* map the zero page RO */
+ map_kernel_page((unsigned long)kasan_zero_page,
+ __pa(kasan_zero_page), PAGE_KERNEL_RO);
+
+ kasan_init_tags();
+
+ /* Turn on checking */
+ static_branch_inc(&powerpc_kasan_enabled_key);
+
+ /* Enable error messages */
+ init_task.kasan_depth = 0;
+ pr_info("KASAN init done (64-bit Book3E)\n");
+}
diff --git a/arch/powerpc/purgatory/Makefile b/arch/powerpc/purgatory/Makefile
index 4314ba5baf43..7c6d8b14f440 100644
--- a/arch/powerpc/purgatory/Makefile
+++ b/arch/powerpc/purgatory/Makefile
@@ -1,4 +1,7 @@
# SPDX-License-Identifier: GPL-2.0
+
+KASAN_SANITIZE := n
+
targets += trampoline.o purgatory.ro kexec-purgatory.c
LDFLAGS_purgatory.ro := -e purgatory_start -r --no-undefined
diff --git a/arch/powerpc/xmon/Makefile b/arch/powerpc/xmon/Makefile
index 878f9c1d3615..064f7062c0a3 100644
--- a/arch/powerpc/xmon/Makefile
+++ b/arch/powerpc/xmon/Makefile
@@ -6,6 +6,7 @@ subdir-ccflags-y := $(call cc-disable-warning, builtin-requires-header)
GCOV_PROFILE := n
UBSAN_SANITIZE := n
+KASAN_SANITIZE := n
# Disable ftrace for the entire directory
ORIG_CFLAGS := $(KBUILD_CFLAGS)
--
2.19.1
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