[RFC WIP PATCH 3/3] powerpc: KASAN for 64bit Book3E
Christophe Leroy
christophe.leroy at c-s.fr
Wed Feb 20 04:29:57 AEDT 2019
From: Daniel Axtens <dja at axtens.net>
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 kasan_arch_is_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>
---
arch/powerpc/Kconfig | 1 +
arch/powerpc/Makefile | 2 +
arch/powerpc/include/asm/kasan.h | 56 +++++++++++++++++++++++++++-
arch/powerpc/mm/Makefile | 2 +
arch/powerpc/mm/kasan/Makefile | 1 +
arch/powerpc/mm/kasan/kasan_init_book3e_64.c | 51 +++++++++++++++++++++++++
6 files changed, 112 insertions(+), 1 deletion(-)
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 06d085558d21..d1943d892db2 100644
--- a/arch/powerpc/Makefile
+++ b/arch/powerpc/Makefile
@@ -428,6 +428,7 @@ endif
endif
ifdef CONFIG_KASAN
+ifdef CONFIG_PPC32
ifndef CONFIG_PPC_BOOK3S_32
prepare: kasan_prepare
@@ -435,6 +436,7 @@ kasan_prepare: prepare0
$(eval KASAN_SHADOW_OFFSET = $(shell awk '{if ($$2 == "KASAN_SHADOW_OFFSET") print $$3;}' include/generated/asm-offsets.h))
endif
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 97b5ccf0702f..6b2cd5ade185 100644
--- a/arch/powerpc/include/asm/kasan.h
+++ b/arch/powerpc/include/asm/kasan.h
@@ -15,6 +15,7 @@
#ifndef __ASSEMBLY__
#include <asm/page.h>
+#include <asm/pgtable.h>
#include <asm/pgtable-types.h>
#include <linux/jump_label.h>
@@ -25,6 +26,7 @@
#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, \
@@ -33,13 +35,15 @@
#define KASAN_SHADOW_SIZE ((~0UL - PAGE_OFFSET + 1) >> KASAN_SHADOW_SCALE_SHIFT)
void kasan_early_init(void);
+#endif /* CONFIG_PPC32 */
+
void kasan_init(void);
extern struct static_key_false powerpc_kasan_enabled_key;
static inline bool kasan_arch_is_ready(void)
{
- if (!IS_ENABLED(CONFIG_BOOK3S_32))
+ if (IS_ENABLED(CONFIG_PPC_32) && !IS_ENABLED(CONFIG_BOOK3S_32))
return true;
if (static_branch_likely(&powerpc_kasan_enabled_key))
return true;
@@ -47,5 +51,55 @@ static inline bool kasan_arch_is_ready(void)
}
#define kasan_arch_is_ready kasan_arch_is_ready
+#ifdef CONFIG_PPC_BOOK3E_64
+#define KASAN_SHADOW_START VMEMMAP_BASE
+#define KASAN_SHADOW_SIZE (KERN_VIRT_SIZE >> KASAN_SHADOW_SCALE_SHIFT)
+
+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_early_shadow_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_early_shadow_page &&
+ shadow_addr < (void *)(kasan_early_shadow_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 */
+
#endif /* __ASSEMBLY */
#endif
diff --git a/arch/powerpc/mm/Makefile b/arch/powerpc/mm/Makefile
index 292b96ce1efc..ab2ed80d224d 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..b37fceebcc3b
--- /dev/null
+++ b/arch/powerpc/mm/kasan/kasan_init_book3e_64.c
@@ -0,0 +1,51 @@
+// 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);
+
+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_early_shadow_page,
+ __pa(kasan_early_shadow_page), PAGE_KERNEL_RO);
+
+ /* 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");
+}
--
2.13.3
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