* Re: [PATCH v5 3/3] powerpc/32: Add KASAN support
[not found] ` <3429fe33b68206ecc2a725a740937bbaef2d1ac8.1549935251.git.christophe.leroy@c-s.fr>
@ 2019-02-14 22:04 ` Daniel Axtens
2019-02-15 8:41 ` Christophe Leroy
2019-02-18 9:27 ` Michael Ellerman
1 sibling, 1 reply; 7+ messages in thread
From: Daniel Axtens @ 2019-02-14 22:04 UTC (permalink / raw)
To: Christophe Leroy, Benjamin Herrenschmidt, Paul Mackerras,
Michael Ellerman, Nicholas Piggin, Aneesh Kumar K.V,
Andrey Ryabinin, Alexander Potapenko, Dmitry Vyukov
Cc: linux-kernel, linuxppc-dev, kasan-dev, linux-mm
Hi Christophe,
> --- a/arch/powerpc/include/asm/string.h
> +++ b/arch/powerpc/include/asm/string.h
> @@ -27,6 +27,20 @@ extern int memcmp(const void *,const void *,__kernel_size_t);
> extern void * memchr(const void *,int,__kernel_size_t);
> extern void * memcpy_flushcache(void *,const void *,__kernel_size_t);
>
> +void *__memset(void *s, int c, __kernel_size_t count);
> +void *__memcpy(void *to, const void *from, __kernel_size_t n);
> +void *__memmove(void *to, const void *from, __kernel_size_t n);
> +
> +#if defined(CONFIG_KASAN) && !defined(__SANITIZE_ADDRESS__)
> +/*
> + * For files that are not instrumented (e.g. mm/slub.c) we
> + * should use not instrumented version of mem* functions.
> + */
> +#define memcpy(dst, src, len) __memcpy(dst, src, len)
> +#define memmove(dst, src, len) __memmove(dst, src, len)
> +#define memset(s, c, n) __memset(s, c, n)
> +#endif
> +
I'm finding that I miss tests like 'kasan test: kasan_memcmp
out-of-bounds in memcmp' because the uninstrumented asm version is used
instead of an instrumented C version. I ended up guarding the relevant
__HAVE_ARCH_x symbols behind a #ifndef CONFIG_KASAN and only exporting
the arch versions if we're not compiled with KASAN.
I find I need to guard and unexport strncpy, strncmp, memchr and
memcmp. Do you need to do this on 32bit as well, or are those tests
passing anyway for some reason?
Regards,
Daniel
> #ifdef CONFIG_PPC64
> #define __HAVE_ARCH_MEMSET32
> #define __HAVE_ARCH_MEMSET64
> diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
> index 879b36602748..fc4c42262694 100644
> --- a/arch/powerpc/kernel/Makefile
> +++ b/arch/powerpc/kernel/Makefile
> @@ -16,8 +16,9 @@ CFLAGS_prom_init.o += -fPIC
> CFLAGS_btext.o += -fPIC
> endif
>
> -CFLAGS_cputable.o += $(DISABLE_LATENT_ENTROPY_PLUGIN)
> -CFLAGS_prom_init.o += $(DISABLE_LATENT_ENTROPY_PLUGIN)
> +CFLAGS_early_32.o += -DDISABLE_BRANCH_PROFILING
> +CFLAGS_cputable.o += $(DISABLE_LATENT_ENTROPY_PLUGIN) -DDISABLE_BRANCH_PROFILING
> +CFLAGS_prom_init.o += $(DISABLE_LATENT_ENTROPY_PLUGIN) -DDISABLE_BRANCH_PROFILING
> CFLAGS_btext.o += $(DISABLE_LATENT_ENTROPY_PLUGIN)
> CFLAGS_prom.o += $(DISABLE_LATENT_ENTROPY_PLUGIN)
>
> @@ -31,6 +32,10 @@ CFLAGS_REMOVE_btext.o = $(CC_FLAGS_FTRACE)
> CFLAGS_REMOVE_prom.o = $(CC_FLAGS_FTRACE)
> endif
>
> +KASAN_SANITIZE_early_32.o := n
> +KASAN_SANITIZE_cputable.o := n
> +KASAN_SANITIZE_prom_init.o := n
> +
> obj-y := cputable.o ptrace.o syscalls.o \
> irq.o align.o signal_32.o pmc.o vdso.o \
> process.o systbl.o idle.o \
> diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c
> index 9ffc72ded73a..846fb30b1190 100644
> --- a/arch/powerpc/kernel/asm-offsets.c
> +++ b/arch/powerpc/kernel/asm-offsets.c
> @@ -783,5 +783,9 @@ int main(void)
> DEFINE(VIRT_IMMR_BASE, (u64)__fix_to_virt(FIX_IMMR_BASE));
> #endif
>
> +#ifdef CONFIG_KASAN
> + DEFINE(KASAN_SHADOW_OFFSET, KASAN_SHADOW_OFFSET);
> +#endif
> +
> return 0;
> }
> diff --git a/arch/powerpc/kernel/head_32.S b/arch/powerpc/kernel/head_32.S
> index 05b08db3901d..0ec9dec06bc2 100644
> --- a/arch/powerpc/kernel/head_32.S
> +++ b/arch/powerpc/kernel/head_32.S
> @@ -962,6 +962,9 @@ start_here:
> * Do early platform-specific initialization,
> * and set up the MMU.
> */
> +#ifdef CONFIG_KASAN
> + bl kasan_early_init
> +#endif
> li r3,0
> mr r4,r31
> bl machine_init
> diff --git a/arch/powerpc/kernel/head_40x.S b/arch/powerpc/kernel/head_40x.S
> index b19d78410511..5d6ff8fa7e2b 100644
> --- a/arch/powerpc/kernel/head_40x.S
> +++ b/arch/powerpc/kernel/head_40x.S
> @@ -848,6 +848,9 @@ start_here:
> /*
> * Decide what sort of machine this is and initialize the MMU.
> */
> +#ifdef CONFIG_KASAN
> + bl kasan_early_init
> +#endif
> li r3,0
> mr r4,r31
> bl machine_init
> diff --git a/arch/powerpc/kernel/head_44x.S b/arch/powerpc/kernel/head_44x.S
> index bf23c19c92d6..7ca14dff6192 100644
> --- a/arch/powerpc/kernel/head_44x.S
> +++ b/arch/powerpc/kernel/head_44x.S
> @@ -203,6 +203,9 @@ _ENTRY(_start);
> /*
> * Decide what sort of machine this is and initialize the MMU.
> */
> +#ifdef CONFIG_KASAN
> + bl kasan_early_init
> +#endif
> li r3,0
> mr r4,r31
> bl machine_init
> diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
> index 0fea10491f3a..6a644ea2e6b6 100644
> --- a/arch/powerpc/kernel/head_8xx.S
> +++ b/arch/powerpc/kernel/head_8xx.S
> @@ -823,6 +823,9 @@ start_here:
> /*
> * Decide what sort of machine this is and initialize the MMU.
> */
> +#ifdef CONFIG_KASAN
> + bl kasan_early_init
> +#endif
> li r3,0
> mr r4,r31
> bl machine_init
> diff --git a/arch/powerpc/kernel/head_fsl_booke.S b/arch/powerpc/kernel/head_fsl_booke.S
> index 2386ce2a9c6e..4f4585a68850 100644
> --- a/arch/powerpc/kernel/head_fsl_booke.S
> +++ b/arch/powerpc/kernel/head_fsl_booke.S
> @@ -274,6 +274,9 @@ set_ivor:
> /*
> * Decide what sort of machine this is and initialize the MMU.
> */
> +#ifdef CONFIG_KASAN
> + bl kasan_early_init
> +#endif
> mr r3,r30
> mr r4,r31
> bl machine_init
> diff --git a/arch/powerpc/kernel/prom_init_check.sh b/arch/powerpc/kernel/prom_init_check.sh
> index 667df97d2595..da6bb16e0876 100644
> --- a/arch/powerpc/kernel/prom_init_check.sh
> +++ b/arch/powerpc/kernel/prom_init_check.sh
> @@ -16,8 +16,16 @@
> # If you really need to reference something from prom_init.o add
> # it to the list below:
>
> +grep CONFIG_KASAN=y .config >/dev/null
> +if [ $? -eq 0 ]
> +then
> + MEMFCT="__memcpy __memset"
> +else
> + MEMFCT="memcpy memset"
> +fi
> +
> WHITELIST="add_reloc_offset __bss_start __bss_stop copy_and_flush
> -_end enter_prom memcpy memset reloc_offset __secondary_hold
> +_end enter_prom $MEMFCT reloc_offset __secondary_hold
> __secondary_hold_acknowledge __secondary_hold_spinloop __start
> strcmp strcpy strlcpy strlen strncmp strstr kstrtobool logo_linux_clut224
> reloc_got2 kernstart_addr memstart_addr linux_banner _stext
> diff --git a/arch/powerpc/kernel/setup-common.c b/arch/powerpc/kernel/setup-common.c
> index ca00fbb97cf8..16ff1ea66805 100644
> --- a/arch/powerpc/kernel/setup-common.c
> +++ b/arch/powerpc/kernel/setup-common.c
> @@ -978,6 +978,8 @@ void __init setup_arch(char **cmdline_p)
>
> paging_init();
>
> + kasan_init();
> +
> /* Initialize the MMU context management stuff. */
> mmu_context_init();
>
> diff --git a/arch/powerpc/lib/Makefile b/arch/powerpc/lib/Makefile
> index 3bf9fc6fd36c..ce8d4a9f810a 100644
> --- a/arch/powerpc/lib/Makefile
> +++ b/arch/powerpc/lib/Makefile
> @@ -8,6 +8,14 @@ ccflags-$(CONFIG_PPC64) := $(NO_MINIMAL_TOC)
> CFLAGS_REMOVE_code-patching.o = $(CC_FLAGS_FTRACE)
> CFLAGS_REMOVE_feature-fixups.o = $(CC_FLAGS_FTRACE)
>
> +KASAN_SANITIZE_code-patching.o := n
> +KASAN_SANITIZE_feature-fixups.o := n
> +
> +ifdef CONFIG_KASAN
> +CFLAGS_code-patching.o += -DDISABLE_BRANCH_PROFILING
> +CFLAGS_feature-fixups.o += -DDISABLE_BRANCH_PROFILING
> +endif
> +
> obj-y += string.o alloc.o code-patching.o feature-fixups.o
>
> obj-$(CONFIG_PPC32) += div64.o copy_32.o crtsavres.o strlen_32.o
> diff --git a/arch/powerpc/lib/copy_32.S b/arch/powerpc/lib/copy_32.S
> index ba66846fe973..4d8a1c73b4cf 100644
> --- a/arch/powerpc/lib/copy_32.S
> +++ b/arch/powerpc/lib/copy_32.S
> @@ -91,7 +91,8 @@ EXPORT_SYMBOL(memset16)
> * We therefore skip the optimised bloc that uses dcbz. This jump is
> * replaced by a nop once cache is active. This is done in machine_init()
> */
> -_GLOBAL(memset)
> +_GLOBAL(__memset)
> +KASAN_OVERRIDE(memset, __memset)
> cmplwi 0,r5,4
> blt 7f
>
> @@ -163,12 +164,14 @@ EXPORT_SYMBOL(memset)
> * We therefore jump to generic_memcpy which doesn't use dcbz. This jump is
> * replaced by a nop once cache is active. This is done in machine_init()
> */
> -_GLOBAL(memmove)
> +_GLOBAL(__memmove)
> +KASAN_OVERRIDE(memmove, __memmove)
> cmplw 0,r3,r4
> bgt backwards_memcpy
> /* fall through */
>
> -_GLOBAL(memcpy)
> +_GLOBAL(__memcpy)
> +KASAN_OVERRIDE(memcpy, __memcpy)
> 1: b generic_memcpy
> patch_site 1b, patch__memcpy_nocache
>
> diff --git a/arch/powerpc/mm/Makefile b/arch/powerpc/mm/Makefile
> index f965fc33a8b7..d6b76f25f6de 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 = $(CC_FLAGS_FTRACE)
>
> +KASAN_SANITIZE_kasan_init.o := n
> +
> obj-y := fault.o mem.o pgtable.o mmap.o \
> init_$(BITS).o pgtable_$(BITS).o \
> init-common.o mmu_context.o drmem.o
> @@ -55,3 +57,4 @@ obj-$(CONFIG_PPC_BOOK3S_64) += dump_linuxpagetables-book3s64.o
> endif
> obj-$(CONFIG_PPC_HTDUMP) += dump_hashpagetable.o
> obj-$(CONFIG_PPC_MEM_KEYS) += pkeys.o
> +obj-$(CONFIG_KASAN) += kasan_init.o
> diff --git a/arch/powerpc/mm/dump_linuxpagetables.c b/arch/powerpc/mm/dump_linuxpagetables.c
> index 6aa41669ac1a..c862b48118f1 100644
> --- a/arch/powerpc/mm/dump_linuxpagetables.c
> +++ b/arch/powerpc/mm/dump_linuxpagetables.c
> @@ -94,6 +94,10 @@ static struct addr_marker address_markers[] = {
> { 0, "Consistent mem start" },
> { 0, "Consistent mem end" },
> #endif
> +#ifdef CONFIG_KASAN
> + { 0, "kasan shadow mem start" },
> + { 0, "kasan shadow mem end" },
> +#endif
> #ifdef CONFIG_HIGHMEM
> { 0, "Highmem PTEs start" },
> { 0, "Highmem PTEs end" },
> @@ -310,6 +314,10 @@ static void populate_markers(void)
> address_markers[i++].start_address = IOREMAP_TOP +
> CONFIG_CONSISTENT_SIZE;
> #endif
> +#ifdef CONFIG_KASAN
> + address_markers[i++].start_address = KASAN_SHADOW_START;
> + address_markers[i++].start_address = KASAN_SHADOW_END;
> +#endif
> #ifdef CONFIG_HIGHMEM
> address_markers[i++].start_address = PKMAP_BASE;
> address_markers[i++].start_address = PKMAP_ADDR(LAST_PKMAP);
> diff --git a/arch/powerpc/mm/kasan_init.c b/arch/powerpc/mm/kasan_init.c
> new file mode 100644
> index 000000000000..bd8e0a263e12
> --- /dev/null
> +++ b/arch/powerpc/mm/kasan_init.c
> @@ -0,0 +1,114 @@
> +// 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>
> +
> +void __init kasan_early_init(void)
> +{
> + unsigned long addr = KASAN_SHADOW_START;
> + unsigned long end = KASAN_SHADOW_END;
> + unsigned long next;
> + pmd_t *pmd = pmd_offset(pud_offset(pgd_offset_k(addr), addr), addr);
> + int i;
> + phys_addr_t pa = __pa(kasan_early_shadow_page);
> +
> + BUILD_BUG_ON(KASAN_SHADOW_START & ~PGDIR_MASK);
> +
> + if (early_mmu_has_feature(MMU_FTR_HPTE_TABLE))
> + panic("KASAN not supported with Hash MMU\n");
> +
> + for (i = 0; i < PTRS_PER_PTE; i++)
> + __set_pte_at(&init_mm, (unsigned long)kasan_early_shadow_page,
> + kasan_early_shadow_pte + i,
> + pfn_pte(PHYS_PFN(pa), PAGE_KERNEL), 0);
> +
> + do {
> + next = pgd_addr_end(addr, end);
> + pmd_populate_kernel(&init_mm, pmd, kasan_early_shadow_pte);
> + } while (pmd++, addr = next, addr != end);
> +}
> +
> +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, k_next;
> + pmd_t *pmd;
> + void *block;
> +
> + if (start >= end)
> + return;
> +
> + k_start = (unsigned long)kasan_mem_to_shadow(start);
> + k_end = (unsigned long)kasan_mem_to_shadow(end);
> + pmd = pmd_offset(pud_offset(pgd_offset_k(k_start), k_start), k_start);
> +
> + for (k_cur = k_start; k_cur != k_end; k_cur = k_next, pmd++) {
> + k_next = pgd_addr_end(k_cur, k_end);
> + if ((void *)pmd_page_vaddr(*pmd) == kasan_early_shadow_pte) {
> + pte_t *new = pte_alloc_one_kernel(&init_mm);
> +
> + if (!new)
> + panic("kasan: pte_alloc_one_kernel() failed");
> + memcpy(new, kasan_early_shadow_pte, PTE_TABLE_SIZE);
> + pmd_populate_kernel(&init_mm, pmd, new);
> + }
> + };
> +
> + block = memblock_alloc(k_end - k_start, PAGE_SIZE);
> + for (k_cur = k_start; k_cur < k_end; k_cur += PAGE_SIZE) {
> + void *va = block ? block + k_cur - k_start :
> + memblock_alloc(PAGE_SIZE, PAGE_SIZE);
> + pte_t pte = pfn_pte(PHYS_PFN(__pa(va)), PAGE_KERNEL);
> +
> + if (!va)
> + panic("kasan: memblock_alloc() failed");
> + pmd = pmd_offset(pud_offset(pgd_offset_k(k_cur), k_cur), k_cur);
> + pte_update(pte_offset_kernel(pmd, k_cur), ~0, pte_val(pte));
> + }
> + flush_tlb_kernel_range(k_start, k_end);
> +}
> +
> +static void __init kasan_remap_early_shadow_ro(void)
> +{
> + unsigned long k_cur;
> + phys_addr_t pa = __pa(kasan_early_shadow_page);
> + int i;
> +
> + for (i = 0; i < PTRS_PER_PTE; i++)
> + ptep_set_wrprotect(&init_mm, 0, kasan_early_shadow_pte + i);
> +
> + for (k_cur = PAGE_OFFSET & PAGE_MASK; k_cur; k_cur += PAGE_SIZE) {
> + pmd_t *pmd = pmd_offset(pud_offset(pgd_offset_k(k_cur), k_cur), k_cur);
> + pte_t *ptep = pte_offset_kernel(pmd, k_cur);
> +
> + if ((void *)pmd_page_vaddr(*pmd) == kasan_early_shadow_pte)
> + continue;
> + if ((pte_val(*ptep) & PAGE_MASK) != pa)
> + continue;
> +
> + ptep_set_wrprotect(&init_mm, k_cur, ptep);
> + }
> + flush_tlb_mm(&init_mm);
> +}
> +
> +void __init kasan_init(void)
> +{
> + struct memblock_region *reg;
> +
> + for_each_memblock(memory, reg)
> + kasan_init_region(reg);
> +
> + kasan_remap_early_shadow_ro();
> +
> + clear_page(kasan_early_shadow_page);
> +
> + /* At this point kasan is fully initialized. Enable error messages */
> + init_task.kasan_depth = 0;
> + pr_info("KASAN init done\n");
> +}
> diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
> index 81f251fc4169..1bb055775e60 100644
> --- a/arch/powerpc/mm/mem.c
> +++ b/arch/powerpc/mm/mem.c
> @@ -336,6 +336,10 @@ void __init mem_init(void)
> pr_info(" * 0x%08lx..0x%08lx : highmem PTEs\n",
> PKMAP_BASE, PKMAP_ADDR(LAST_PKMAP));
> #endif /* CONFIG_HIGHMEM */
> +#ifdef CONFIG_KASAN
> + pr_info(" * 0x%08lx..0x%08lx : kasan shadow mem\n",
> + KASAN_SHADOW_START, KASAN_SHADOW_END);
> +#endif
> #ifdef CONFIG_NOT_COHERENT_CACHE
> pr_info(" * 0x%08lx..0x%08lx : consistent mem\n",
> IOREMAP_TOP, IOREMAP_TOP + CONFIG_CONSISTENT_SIZE);
> --
> 2.13.3
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v5 3/3] powerpc/32: Add KASAN support
2019-02-14 22:04 ` [PATCH v5 3/3] powerpc/32: Add KASAN support Daniel Axtens
@ 2019-02-15 8:41 ` Christophe Leroy
2019-02-15 10:01 ` Andrey Ryabinin
0 siblings, 1 reply; 7+ messages in thread
From: Christophe Leroy @ 2019-02-15 8:41 UTC (permalink / raw)
To: Daniel Axtens, Benjamin Herrenschmidt, Paul Mackerras,
Michael Ellerman, Nicholas Piggin, Aneesh Kumar K.V,
Andrey Ryabinin, Alexander Potapenko, Dmitry Vyukov
Cc: linux-kernel, linuxppc-dev, kasan-dev, linux-mm
Le 14/02/2019 à 23:04, Daniel Axtens a écrit :
> Hi Christophe,
>
>> --- a/arch/powerpc/include/asm/string.h
>> +++ b/arch/powerpc/include/asm/string.h
>> @@ -27,6 +27,20 @@ extern int memcmp(const void *,const void *,__kernel_size_t);
>> extern void * memchr(const void *,int,__kernel_size_t);
>> extern void * memcpy_flushcache(void *,const void *,__kernel_size_t);
>>
>> +void *__memset(void *s, int c, __kernel_size_t count);
>> +void *__memcpy(void *to, const void *from, __kernel_size_t n);
>> +void *__memmove(void *to, const void *from, __kernel_size_t n);
>> +
>> +#if defined(CONFIG_KASAN) && !defined(__SANITIZE_ADDRESS__)
>> +/*
>> + * For files that are not instrumented (e.g. mm/slub.c) we
>> + * should use not instrumented version of mem* functions.
>> + */
>> +#define memcpy(dst, src, len) __memcpy(dst, src, len)
>> +#define memmove(dst, src, len) __memmove(dst, src, len)
>> +#define memset(s, c, n) __memset(s, c, n)
>> +#endif
>> +
>
> I'm finding that I miss tests like 'kasan test: kasan_memcmp
> out-of-bounds in memcmp' because the uninstrumented asm version is used
> instead of an instrumented C version. I ended up guarding the relevant
> __HAVE_ARCH_x symbols behind a #ifndef CONFIG_KASAN and only exporting
> the arch versions if we're not compiled with KASAN.
>
> I find I need to guard and unexport strncpy, strncmp, memchr and
> memcmp. Do you need to do this on 32bit as well, or are those tests
> passing anyway for some reason?
Indeed, I didn't try the KASAN test module recently, because my configs
don't have CONFIG_MODULE by default.
Trying to test it now, I am discovering that module loading oopses with
latest version of my series, I need to figure out exactly why. Here
below the oops by modprobing test_module (the one supposed to just say
hello to the world).
What we see is an access to the RO kasan zero area.
The shadow mem is 0xf7c00000..0xffc00000
Linear kernel memory is shadowed by 0xf7c00000-0xf8bfffff
0xf8c00000-0xffc00000 is shadowed read only by the kasan zero page.
Why is kasan trying to access that ? Isn't kasan supposed to not check
stuff in vmalloc area ?
[ 189.087499] BUG: Unable to handle kernel data access at 0xf8eb7818
[ 189.093455] Faulting instruction address: 0xc001ab60
[ 189.098383] Oops: Kernel access of bad area, sig: 11 [#1]
[ 189.103732] BE PAGE_SIZE=16K PREEMPT CMPC885
[ 189.111414] Modules linked in: test_module(+)
[ 189.115817] CPU: 0 PID: 514 Comm: modprobe Not tainted
5.0.0-rc5-s3k-dev-00645-g1dd3acf23952 #1016
[ 189.124627] NIP: c001ab60 LR: c0194fe8 CTR: 00000003
[ 189.129641] REGS: c5645b90 TRAP: 0300 Not tainted
(5.0.0-rc5-s3k-dev-00645-g1dd3acf23952)
[ 189.137924] MSR: 00009032 <EE,ME,IR,DR,RI> CR: 44002884 XER: 00000000
[ 189.144571] DAR: f8eb7818 DSISR: 8a000000
[ 189.144571] GPR00: c0196620 c5645c40 c5aac000 f8eb7818 00000000
00000003 f8eb7817 c01950d0
[ 189.144571] GPR08: c00c2720 c95bc010 00000000 c95bc1a0 c01965ec
100d7b30 c0802b80 c5ae0308
[ 189.144571] GPR16: c5990480 00000124 0000000f c00bcf7c c5ae0324
c95bc32c 000006b8 00000001
[ 189.144571] GPR24: c95bc364 c95bc360 c95bc2c0 c95bc1a0 00000002
00000000 00000018 f8eb781b
[ 189.182611] NIP [c001ab60] __memset+0xb4/0xc0
[ 189.186922] LR [c0194fe8] kasan_unpoison_shadow+0x34/0x54
[ 189.192136] Call Trace:
[ 189.194682] [c5645c50] [c0196620] __asan_register_globals+0x34/0x74
[ 189.200900] [c5645c70] [c00c27a4] do_init_module+0xbc/0x5a4
[ 189.206392] [c5645ca0] [c00c0d08] load_module+0x2b5c/0x3194
[ 189.211901] [c5645e70] [c00c14c8] sys_init_module+0x188/0x1bc
[ 189.217572] [c5645f40] [c001311c] ret_from_syscall+0x0/0x38
[ 189.223049] --- interrupt: c01 at 0xfda2b50
[ 189.223049] LR = 0x10014b18
[ 189.230175] Instruction dump:
[ 189.233117] 4200fffc 70a50003 4d820020 7ca903a6 38c60003 9c860001
4200fffc 4e800020
[ 189.240859] 2c050000 4d820020 7ca903a6 38c3ffff <9c860001> 4200fffc
4e800020 7c032040
[ 189.248809] ---[ end trace 45cbb1b3215e5959 ]---
Christophe
>
> Regards,
> Daniel
>
>
>> #ifdef CONFIG_PPC64
>> #define __HAVE_ARCH_MEMSET32
>> #define __HAVE_ARCH_MEMSET64
>> diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
>> index 879b36602748..fc4c42262694 100644
>> --- a/arch/powerpc/kernel/Makefile
>> +++ b/arch/powerpc/kernel/Makefile
>> @@ -16,8 +16,9 @@ CFLAGS_prom_init.o += -fPIC
>> CFLAGS_btext.o += -fPIC
>> endif
>>
>> -CFLAGS_cputable.o += $(DISABLE_LATENT_ENTROPY_PLUGIN)
>> -CFLAGS_prom_init.o += $(DISABLE_LATENT_ENTROPY_PLUGIN)
>> +CFLAGS_early_32.o += -DDISABLE_BRANCH_PROFILING
>> +CFLAGS_cputable.o += $(DISABLE_LATENT_ENTROPY_PLUGIN) -DDISABLE_BRANCH_PROFILING
>> +CFLAGS_prom_init.o += $(DISABLE_LATENT_ENTROPY_PLUGIN) -DDISABLE_BRANCH_PROFILING
>> CFLAGS_btext.o += $(DISABLE_LATENT_ENTROPY_PLUGIN)
>> CFLAGS_prom.o += $(DISABLE_LATENT_ENTROPY_PLUGIN)
>>
>> @@ -31,6 +32,10 @@ CFLAGS_REMOVE_btext.o = $(CC_FLAGS_FTRACE)
>> CFLAGS_REMOVE_prom.o = $(CC_FLAGS_FTRACE)
>> endif
>>
>> +KASAN_SANITIZE_early_32.o := n
>> +KASAN_SANITIZE_cputable.o := n
>> +KASAN_SANITIZE_prom_init.o := n
>> +
>> obj-y := cputable.o ptrace.o syscalls.o \
>> irq.o align.o signal_32.o pmc.o vdso.o \
>> process.o systbl.o idle.o \
>> diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c
>> index 9ffc72ded73a..846fb30b1190 100644
>> --- a/arch/powerpc/kernel/asm-offsets.c
>> +++ b/arch/powerpc/kernel/asm-offsets.c
>> @@ -783,5 +783,9 @@ int main(void)
>> DEFINE(VIRT_IMMR_BASE, (u64)__fix_to_virt(FIX_IMMR_BASE));
>> #endif
>>
>> +#ifdef CONFIG_KASAN
>> + DEFINE(KASAN_SHADOW_OFFSET, KASAN_SHADOW_OFFSET);
>> +#endif
>> +
>> return 0;
>> }
>> diff --git a/arch/powerpc/kernel/head_32.S b/arch/powerpc/kernel/head_32.S
>> index 05b08db3901d..0ec9dec06bc2 100644
>> --- a/arch/powerpc/kernel/head_32.S
>> +++ b/arch/powerpc/kernel/head_32.S
>> @@ -962,6 +962,9 @@ start_here:
>> * Do early platform-specific initialization,
>> * and set up the MMU.
>> */
>> +#ifdef CONFIG_KASAN
>> + bl kasan_early_init
>> +#endif
>> li r3,0
>> mr r4,r31
>> bl machine_init
>> diff --git a/arch/powerpc/kernel/head_40x.S b/arch/powerpc/kernel/head_40x.S
>> index b19d78410511..5d6ff8fa7e2b 100644
>> --- a/arch/powerpc/kernel/head_40x.S
>> +++ b/arch/powerpc/kernel/head_40x.S
>> @@ -848,6 +848,9 @@ start_here:
>> /*
>> * Decide what sort of machine this is and initialize the MMU.
>> */
>> +#ifdef CONFIG_KASAN
>> + bl kasan_early_init
>> +#endif
>> li r3,0
>> mr r4,r31
>> bl machine_init
>> diff --git a/arch/powerpc/kernel/head_44x.S b/arch/powerpc/kernel/head_44x.S
>> index bf23c19c92d6..7ca14dff6192 100644
>> --- a/arch/powerpc/kernel/head_44x.S
>> +++ b/arch/powerpc/kernel/head_44x.S
>> @@ -203,6 +203,9 @@ _ENTRY(_start);
>> /*
>> * Decide what sort of machine this is and initialize the MMU.
>> */
>> +#ifdef CONFIG_KASAN
>> + bl kasan_early_init
>> +#endif
>> li r3,0
>> mr r4,r31
>> bl machine_init
>> diff --git a/arch/powerpc/kernel/head_8xx.S b/arch/powerpc/kernel/head_8xx.S
>> index 0fea10491f3a..6a644ea2e6b6 100644
>> --- a/arch/powerpc/kernel/head_8xx.S
>> +++ b/arch/powerpc/kernel/head_8xx.S
>> @@ -823,6 +823,9 @@ start_here:
>> /*
>> * Decide what sort of machine this is and initialize the MMU.
>> */
>> +#ifdef CONFIG_KASAN
>> + bl kasan_early_init
>> +#endif
>> li r3,0
>> mr r4,r31
>> bl machine_init
>> diff --git a/arch/powerpc/kernel/head_fsl_booke.S b/arch/powerpc/kernel/head_fsl_booke.S
>> index 2386ce2a9c6e..4f4585a68850 100644
>> --- a/arch/powerpc/kernel/head_fsl_booke.S
>> +++ b/arch/powerpc/kernel/head_fsl_booke.S
>> @@ -274,6 +274,9 @@ set_ivor:
>> /*
>> * Decide what sort of machine this is and initialize the MMU.
>> */
>> +#ifdef CONFIG_KASAN
>> + bl kasan_early_init
>> +#endif
>> mr r3,r30
>> mr r4,r31
>> bl machine_init
>> diff --git a/arch/powerpc/kernel/prom_init_check.sh b/arch/powerpc/kernel/prom_init_check.sh
>> index 667df97d2595..da6bb16e0876 100644
>> --- a/arch/powerpc/kernel/prom_init_check.sh
>> +++ b/arch/powerpc/kernel/prom_init_check.sh
>> @@ -16,8 +16,16 @@
>> # If you really need to reference something from prom_init.o add
>> # it to the list below:
>>
>> +grep CONFIG_KASAN=y .config >/dev/null
>> +if [ $? -eq 0 ]
>> +then
>> + MEMFCT="__memcpy __memset"
>> +else
>> + MEMFCT="memcpy memset"
>> +fi
>> +
>> WHITELIST="add_reloc_offset __bss_start __bss_stop copy_and_flush
>> -_end enter_prom memcpy memset reloc_offset __secondary_hold
>> +_end enter_prom $MEMFCT reloc_offset __secondary_hold
>> __secondary_hold_acknowledge __secondary_hold_spinloop __start
>> strcmp strcpy strlcpy strlen strncmp strstr kstrtobool logo_linux_clut224
>> reloc_got2 kernstart_addr memstart_addr linux_banner _stext
>> diff --git a/arch/powerpc/kernel/setup-common.c b/arch/powerpc/kernel/setup-common.c
>> index ca00fbb97cf8..16ff1ea66805 100644
>> --- a/arch/powerpc/kernel/setup-common.c
>> +++ b/arch/powerpc/kernel/setup-common.c
>> @@ -978,6 +978,8 @@ void __init setup_arch(char **cmdline_p)
>>
>> paging_init();
>>
>> + kasan_init();
>> +
>> /* Initialize the MMU context management stuff. */
>> mmu_context_init();
>>
>> diff --git a/arch/powerpc/lib/Makefile b/arch/powerpc/lib/Makefile
>> index 3bf9fc6fd36c..ce8d4a9f810a 100644
>> --- a/arch/powerpc/lib/Makefile
>> +++ b/arch/powerpc/lib/Makefile
>> @@ -8,6 +8,14 @@ ccflags-$(CONFIG_PPC64) := $(NO_MINIMAL_TOC)
>> CFLAGS_REMOVE_code-patching.o = $(CC_FLAGS_FTRACE)
>> CFLAGS_REMOVE_feature-fixups.o = $(CC_FLAGS_FTRACE)
>>
>> +KASAN_SANITIZE_code-patching.o := n
>> +KASAN_SANITIZE_feature-fixups.o := n
>> +
>> +ifdef CONFIG_KASAN
>> +CFLAGS_code-patching.o += -DDISABLE_BRANCH_PROFILING
>> +CFLAGS_feature-fixups.o += -DDISABLE_BRANCH_PROFILING
>> +endif
>> +
>> obj-y += string.o alloc.o code-patching.o feature-fixups.o
>>
>> obj-$(CONFIG_PPC32) += div64.o copy_32.o crtsavres.o strlen_32.o
>> diff --git a/arch/powerpc/lib/copy_32.S b/arch/powerpc/lib/copy_32.S
>> index ba66846fe973..4d8a1c73b4cf 100644
>> --- a/arch/powerpc/lib/copy_32.S
>> +++ b/arch/powerpc/lib/copy_32.S
>> @@ -91,7 +91,8 @@ EXPORT_SYMBOL(memset16)
>> * We therefore skip the optimised bloc that uses dcbz. This jump is
>> * replaced by a nop once cache is active. This is done in machine_init()
>> */
>> -_GLOBAL(memset)
>> +_GLOBAL(__memset)
>> +KASAN_OVERRIDE(memset, __memset)
>> cmplwi 0,r5,4
>> blt 7f
>>
>> @@ -163,12 +164,14 @@ EXPORT_SYMBOL(memset)
>> * We therefore jump to generic_memcpy which doesn't use dcbz. This jump is
>> * replaced by a nop once cache is active. This is done in machine_init()
>> */
>> -_GLOBAL(memmove)
>> +_GLOBAL(__memmove)
>> +KASAN_OVERRIDE(memmove, __memmove)
>> cmplw 0,r3,r4
>> bgt backwards_memcpy
>> /* fall through */
>>
>> -_GLOBAL(memcpy)
>> +_GLOBAL(__memcpy)
>> +KASAN_OVERRIDE(memcpy, __memcpy)
>> 1: b generic_memcpy
>> patch_site 1b, patch__memcpy_nocache
>>
>> diff --git a/arch/powerpc/mm/Makefile b/arch/powerpc/mm/Makefile
>> index f965fc33a8b7..d6b76f25f6de 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 = $(CC_FLAGS_FTRACE)
>>
>> +KASAN_SANITIZE_kasan_init.o := n
>> +
>> obj-y := fault.o mem.o pgtable.o mmap.o \
>> init_$(BITS).o pgtable_$(BITS).o \
>> init-common.o mmu_context.o drmem.o
>> @@ -55,3 +57,4 @@ obj-$(CONFIG_PPC_BOOK3S_64) += dump_linuxpagetables-book3s64.o
>> endif
>> obj-$(CONFIG_PPC_HTDUMP) += dump_hashpagetable.o
>> obj-$(CONFIG_PPC_MEM_KEYS) += pkeys.o
>> +obj-$(CONFIG_KASAN) += kasan_init.o
>> diff --git a/arch/powerpc/mm/dump_linuxpagetables.c b/arch/powerpc/mm/dump_linuxpagetables.c
>> index 6aa41669ac1a..c862b48118f1 100644
>> --- a/arch/powerpc/mm/dump_linuxpagetables.c
>> +++ b/arch/powerpc/mm/dump_linuxpagetables.c
>> @@ -94,6 +94,10 @@ static struct addr_marker address_markers[] = {
>> { 0, "Consistent mem start" },
>> { 0, "Consistent mem end" },
>> #endif
>> +#ifdef CONFIG_KASAN
>> + { 0, "kasan shadow mem start" },
>> + { 0, "kasan shadow mem end" },
>> +#endif
>> #ifdef CONFIG_HIGHMEM
>> { 0, "Highmem PTEs start" },
>> { 0, "Highmem PTEs end" },
>> @@ -310,6 +314,10 @@ static void populate_markers(void)
>> address_markers[i++].start_address = IOREMAP_TOP +
>> CONFIG_CONSISTENT_SIZE;
>> #endif
>> +#ifdef CONFIG_KASAN
>> + address_markers[i++].start_address = KASAN_SHADOW_START;
>> + address_markers[i++].start_address = KASAN_SHADOW_END;
>> +#endif
>> #ifdef CONFIG_HIGHMEM
>> address_markers[i++].start_address = PKMAP_BASE;
>> address_markers[i++].start_address = PKMAP_ADDR(LAST_PKMAP);
>> diff --git a/arch/powerpc/mm/kasan_init.c b/arch/powerpc/mm/kasan_init.c
>> new file mode 100644
>> index 000000000000..bd8e0a263e12
>> --- /dev/null
>> +++ b/arch/powerpc/mm/kasan_init.c
>> @@ -0,0 +1,114 @@
>> +// 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>
>> +
>> +void __init kasan_early_init(void)
>> +{
>> + unsigned long addr = KASAN_SHADOW_START;
>> + unsigned long end = KASAN_SHADOW_END;
>> + unsigned long next;
>> + pmd_t *pmd = pmd_offset(pud_offset(pgd_offset_k(addr), addr), addr);
>> + int i;
>> + phys_addr_t pa = __pa(kasan_early_shadow_page);
>> +
>> + BUILD_BUG_ON(KASAN_SHADOW_START & ~PGDIR_MASK);
>> +
>> + if (early_mmu_has_feature(MMU_FTR_HPTE_TABLE))
>> + panic("KASAN not supported with Hash MMU\n");
>> +
>> + for (i = 0; i < PTRS_PER_PTE; i++)
>> + __set_pte_at(&init_mm, (unsigned long)kasan_early_shadow_page,
>> + kasan_early_shadow_pte + i,
>> + pfn_pte(PHYS_PFN(pa), PAGE_KERNEL), 0);
>> +
>> + do {
>> + next = pgd_addr_end(addr, end);
>> + pmd_populate_kernel(&init_mm, pmd, kasan_early_shadow_pte);
>> + } while (pmd++, addr = next, addr != end);
>> +}
>> +
>> +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, k_next;
>> + pmd_t *pmd;
>> + void *block;
>> +
>> + if (start >= end)
>> + return;
>> +
>> + k_start = (unsigned long)kasan_mem_to_shadow(start);
>> + k_end = (unsigned long)kasan_mem_to_shadow(end);
>> + pmd = pmd_offset(pud_offset(pgd_offset_k(k_start), k_start), k_start);
>> +
>> + for (k_cur = k_start; k_cur != k_end; k_cur = k_next, pmd++) {
>> + k_next = pgd_addr_end(k_cur, k_end);
>> + if ((void *)pmd_page_vaddr(*pmd) == kasan_early_shadow_pte) {
>> + pte_t *new = pte_alloc_one_kernel(&init_mm);
>> +
>> + if (!new)
>> + panic("kasan: pte_alloc_one_kernel() failed");
>> + memcpy(new, kasan_early_shadow_pte, PTE_TABLE_SIZE);
>> + pmd_populate_kernel(&init_mm, pmd, new);
>> + }
>> + };
>> +
>> + block = memblock_alloc(k_end - k_start, PAGE_SIZE);
>> + for (k_cur = k_start; k_cur < k_end; k_cur += PAGE_SIZE) {
>> + void *va = block ? block + k_cur - k_start :
>> + memblock_alloc(PAGE_SIZE, PAGE_SIZE);
>> + pte_t pte = pfn_pte(PHYS_PFN(__pa(va)), PAGE_KERNEL);
>> +
>> + if (!va)
>> + panic("kasan: memblock_alloc() failed");
>> + pmd = pmd_offset(pud_offset(pgd_offset_k(k_cur), k_cur), k_cur);
>> + pte_update(pte_offset_kernel(pmd, k_cur), ~0, pte_val(pte));
>> + }
>> + flush_tlb_kernel_range(k_start, k_end);
>> +}
>> +
>> +static void __init kasan_remap_early_shadow_ro(void)
>> +{
>> + unsigned long k_cur;
>> + phys_addr_t pa = __pa(kasan_early_shadow_page);
>> + int i;
>> +
>> + for (i = 0; i < PTRS_PER_PTE; i++)
>> + ptep_set_wrprotect(&init_mm, 0, kasan_early_shadow_pte + i);
>> +
>> + for (k_cur = PAGE_OFFSET & PAGE_MASK; k_cur; k_cur += PAGE_SIZE) {
>> + pmd_t *pmd = pmd_offset(pud_offset(pgd_offset_k(k_cur), k_cur), k_cur);
>> + pte_t *ptep = pte_offset_kernel(pmd, k_cur);
>> +
>> + if ((void *)pmd_page_vaddr(*pmd) == kasan_early_shadow_pte)
>> + continue;
>> + if ((pte_val(*ptep) & PAGE_MASK) != pa)
>> + continue;
>> +
>> + ptep_set_wrprotect(&init_mm, k_cur, ptep);
>> + }
>> + flush_tlb_mm(&init_mm);
>> +}
>> +
>> +void __init kasan_init(void)
>> +{
>> + struct memblock_region *reg;
>> +
>> + for_each_memblock(memory, reg)
>> + kasan_init_region(reg);
>> +
>> + kasan_remap_early_shadow_ro();
>> +
>> + clear_page(kasan_early_shadow_page);
>> +
>> + /* At this point kasan is fully initialized. Enable error messages */
>> + init_task.kasan_depth = 0;
>> + pr_info("KASAN init done\n");
>> +}
>> diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
>> index 81f251fc4169..1bb055775e60 100644
>> --- a/arch/powerpc/mm/mem.c
>> +++ b/arch/powerpc/mm/mem.c
>> @@ -336,6 +336,10 @@ void __init mem_init(void)
>> pr_info(" * 0x%08lx..0x%08lx : highmem PTEs\n",
>> PKMAP_BASE, PKMAP_ADDR(LAST_PKMAP));
>> #endif /* CONFIG_HIGHMEM */
>> +#ifdef CONFIG_KASAN
>> + pr_info(" * 0x%08lx..0x%08lx : kasan shadow mem\n",
>> + KASAN_SHADOW_START, KASAN_SHADOW_END);
>> +#endif
>> #ifdef CONFIG_NOT_COHERENT_CACHE
>> pr_info(" * 0x%08lx..0x%08lx : consistent mem\n",
>> IOREMAP_TOP, IOREMAP_TOP + CONFIG_CONSISTENT_SIZE);
>> --
>> 2.13.3
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v5 3/3] powerpc/32: Add KASAN support
2019-02-15 8:41 ` Christophe Leroy
@ 2019-02-15 10:01 ` Andrey Ryabinin
2019-02-15 10:10 ` Christophe Leroy
0 siblings, 1 reply; 7+ messages in thread
From: Andrey Ryabinin @ 2019-02-15 10:01 UTC (permalink / raw)
To: Christophe Leroy, Daniel Axtens, Benjamin Herrenschmidt,
Paul Mackerras, Michael Ellerman, Nicholas Piggin,
Aneesh Kumar K.V, Alexander Potapenko, Dmitry Vyukov
Cc: linux-kernel, linuxppc-dev, kasan-dev, linux-mm
On 2/15/19 11:41 AM, Christophe Leroy wrote:
>
>
> Le 14/02/2019 à 23:04, Daniel Axtens a écrit :
>> Hi Christophe,
>>
>>> --- a/arch/powerpc/include/asm/string.h
>>> +++ b/arch/powerpc/include/asm/string.h
>>> @@ -27,6 +27,20 @@ extern int memcmp(const void *,const void *,__kernel_size_t);
>>> extern void * memchr(const void *,int,__kernel_size_t);
>>> extern void * memcpy_flushcache(void *,const void *,__kernel_size_t);
>>> +void *__memset(void *s, int c, __kernel_size_t count);
>>> +void *__memcpy(void *to, const void *from, __kernel_size_t n);
>>> +void *__memmove(void *to, const void *from, __kernel_size_t n);
>>> +
>>> +#if defined(CONFIG_KASAN) && !defined(__SANITIZE_ADDRESS__)
>>> +/*
>>> + * For files that are not instrumented (e.g. mm/slub.c) we
>>> + * should use not instrumented version of mem* functions.
>>> + */
>>> +#define memcpy(dst, src, len) __memcpy(dst, src, len)
>>> +#define memmove(dst, src, len) __memmove(dst, src, len)
>>> +#define memset(s, c, n) __memset(s, c, n)
>>> +#endif
>>> +
>>
>> I'm finding that I miss tests like 'kasan test: kasan_memcmp
>> out-of-bounds in memcmp' because the uninstrumented asm version is used
>> instead of an instrumented C version. I ended up guarding the relevant
>> __HAVE_ARCH_x symbols behind a #ifndef CONFIG_KASAN and only exporting
>> the arch versions if we're not compiled with KASAN.
>>
>> I find I need to guard and unexport strncpy, strncmp, memchr and
>> memcmp. Do you need to do this on 32bit as well, or are those tests
>> passing anyway for some reason?
>
> Indeed, I didn't try the KASAN test module recently, because my configs don't have CONFIG_MODULE by default.
>
> Trying to test it now, I am discovering that module loading oopses with latest version of my series, I need to figure out exactly why. Here below the oops by modprobing test_module (the one supposed to just say hello to the world).
>
> What we see is an access to the RO kasan zero area.
>
> The shadow mem is 0xf7c00000..0xffc00000
> Linear kernel memory is shadowed by 0xf7c00000-0xf8bfffff
> 0xf8c00000-0xffc00000 is shadowed read only by the kasan zero page.
>
> Why is kasan trying to access that ? Isn't kasan supposed to not check stuff in vmalloc area ?
It tries to poison global variables in modules. If module is in vmalloc, than it will try to poison vmalloc.
Given that the vmalloc area is not so big on 32bits, the easiest solution is to cover all vmalloc with RW shadow.
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v5 3/3] powerpc/32: Add KASAN support
2019-02-15 10:01 ` Andrey Ryabinin
@ 2019-02-15 10:10 ` Christophe Leroy
2019-02-15 10:38 ` Andrey Ryabinin
0 siblings, 1 reply; 7+ messages in thread
From: Christophe Leroy @ 2019-02-15 10:10 UTC (permalink / raw)
To: Andrey Ryabinin, Daniel Axtens, Benjamin Herrenschmidt,
Paul Mackerras, Michael Ellerman, Nicholas Piggin,
Aneesh Kumar K.V, Alexander Potapenko, Dmitry Vyukov
Cc: linux-kernel, linuxppc-dev, kasan-dev, linux-mm
Le 15/02/2019 à 11:01, Andrey Ryabinin a écrit :
>
>
> On 2/15/19 11:41 AM, Christophe Leroy wrote:
>>
>>
>> Le 14/02/2019 à 23:04, Daniel Axtens a écrit :
>>> Hi Christophe,
>>>
>>>> --- a/arch/powerpc/include/asm/string.h
>>>> +++ b/arch/powerpc/include/asm/string.h
>>>> @@ -27,6 +27,20 @@ extern int memcmp(const void *,const void *,__kernel_size_t);
>>>> extern void * memchr(const void *,int,__kernel_size_t);
>>>> extern void * memcpy_flushcache(void *,const void *,__kernel_size_t);
>>>> +void *__memset(void *s, int c, __kernel_size_t count);
>>>> +void *__memcpy(void *to, const void *from, __kernel_size_t n);
>>>> +void *__memmove(void *to, const void *from, __kernel_size_t n);
>>>> +
>>>> +#if defined(CONFIG_KASAN) && !defined(__SANITIZE_ADDRESS__)
>>>> +/*
>>>> + * For files that are not instrumented (e.g. mm/slub.c) we
>>>> + * should use not instrumented version of mem* functions.
>>>> + */
>>>> +#define memcpy(dst, src, len) __memcpy(dst, src, len)
>>>> +#define memmove(dst, src, len) __memmove(dst, src, len)
>>>> +#define memset(s, c, n) __memset(s, c, n)
>>>> +#endif
>>>> +
>>>
>>> I'm finding that I miss tests like 'kasan test: kasan_memcmp
>>> out-of-bounds in memcmp' because the uninstrumented asm version is used
>>> instead of an instrumented C version. I ended up guarding the relevant
>>> __HAVE_ARCH_x symbols behind a #ifndef CONFIG_KASAN and only exporting
>>> the arch versions if we're not compiled with KASAN.
>>>
>>> I find I need to guard and unexport strncpy, strncmp, memchr and
>>> memcmp. Do you need to do this on 32bit as well, or are those tests
>>> passing anyway for some reason?
>>
>> Indeed, I didn't try the KASAN test module recently, because my configs don't have CONFIG_MODULE by default.
>>
>> Trying to test it now, I am discovering that module loading oopses with latest version of my series, I need to figure out exactly why. Here below the oops by modprobing test_module (the one supposed to just say hello to the world).
>>
>> What we see is an access to the RO kasan zero area.
>>
>> The shadow mem is 0xf7c00000..0xffc00000
>> Linear kernel memory is shadowed by 0xf7c00000-0xf8bfffff
>> 0xf8c00000-0xffc00000 is shadowed read only by the kasan zero page.
>>
>> Why is kasan trying to access that ? Isn't kasan supposed to not check stuff in vmalloc area ?
>
> It tries to poison global variables in modules. If module is in vmalloc, than it will try to poison vmalloc.
> Given that the vmalloc area is not so big on 32bits, the easiest solution is to cover all vmalloc with RW shadow.
>
Euh ... Not so big ?
Memory: 96448K/131072K available (8016K kernel code, 1680K rwdata
, 2720K rodata, 624K init, 4678K bss, 34624K reserved, 0K cma-reserved)
Kernel virtual memory layout:
* 0xffefc000..0xffffc000 : fixmap
* 0xf7c00000..0xffc00000 : kasan shadow mem
* 0xf7a00000..0xf7c00000 : consistent mem
* 0xf7a00000..0xf7a00000 : early ioremap
* 0xc9000000..0xf7a00000 : vmalloc & ioremap
Here, vmalloc area size 0x2ea00000, that is 746Mbytes. Shadow for this
would be 93Mbytes and we are already using 16Mbytes to shadow the linear
memory area .... this poor board has 128Mbytes RAM in total.
So another solution is needed.
Christophe
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v5 3/3] powerpc/32: Add KASAN support
2019-02-15 10:10 ` Christophe Leroy
@ 2019-02-15 10:38 ` Andrey Ryabinin
0 siblings, 0 replies; 7+ messages in thread
From: Andrey Ryabinin @ 2019-02-15 10:38 UTC (permalink / raw)
To: Christophe Leroy, Daniel Axtens, Benjamin Herrenschmidt,
Paul Mackerras, Michael Ellerman, Nicholas Piggin,
Aneesh Kumar K.V, Alexander Potapenko, Dmitry Vyukov
Cc: linux-kernel, linuxppc-dev, kasan-dev, linux-mm
On 2/15/19 1:10 PM, Christophe Leroy wrote:
>
>
> Le 15/02/2019 à 11:01, Andrey Ryabinin a écrit :
>>
>>
>> On 2/15/19 11:41 AM, Christophe Leroy wrote:
>>>
>>>
>>> Le 14/02/2019 à 23:04, Daniel Axtens a écrit :
>>>> Hi Christophe,
>>>>
>>>>> --- a/arch/powerpc/include/asm/string.h
>>>>> +++ b/arch/powerpc/include/asm/string.h
>>>>> @@ -27,6 +27,20 @@ extern int memcmp(const void *,const void *,__kernel_size_t);
>>>>> extern void * memchr(const void *,int,__kernel_size_t);
>>>>> extern void * memcpy_flushcache(void *,const void *,__kernel_size_t);
>>>>> +void *__memset(void *s, int c, __kernel_size_t count);
>>>>> +void *__memcpy(void *to, const void *from, __kernel_size_t n);
>>>>> +void *__memmove(void *to, const void *from, __kernel_size_t n);
>>>>> +
>>>>> +#if defined(CONFIG_KASAN) && !defined(__SANITIZE_ADDRESS__)
>>>>> +/*
>>>>> + * For files that are not instrumented (e.g. mm/slub.c) we
>>>>> + * should use not instrumented version of mem* functions.
>>>>> + */
>>>>> +#define memcpy(dst, src, len) __memcpy(dst, src, len)
>>>>> +#define memmove(dst, src, len) __memmove(dst, src, len)
>>>>> +#define memset(s, c, n) __memset(s, c, n)
>>>>> +#endif
>>>>> +
>>>>
>>>> I'm finding that I miss tests like 'kasan test: kasan_memcmp
>>>> out-of-bounds in memcmp' because the uninstrumented asm version is used
>>>> instead of an instrumented C version. I ended up guarding the relevant
>>>> __HAVE_ARCH_x symbols behind a #ifndef CONFIG_KASAN and only exporting
>>>> the arch versions if we're not compiled with KASAN.
>>>>
>>>> I find I need to guard and unexport strncpy, strncmp, memchr and
>>>> memcmp. Do you need to do this on 32bit as well, or are those tests
>>>> passing anyway for some reason?
>>>
>>> Indeed, I didn't try the KASAN test module recently, because my configs don't have CONFIG_MODULE by default.
>>>
>>> Trying to test it now, I am discovering that module loading oopses with latest version of my series, I need to figure out exactly why. Here below the oops by modprobing test_module (the one supposed to just say hello to the world).
>>>
>>> What we see is an access to the RO kasan zero area.
>>>
>>> The shadow mem is 0xf7c00000..0xffc00000
>>> Linear kernel memory is shadowed by 0xf7c00000-0xf8bfffff
>>> 0xf8c00000-0xffc00000 is shadowed read only by the kasan zero page.
>>>
>>> Why is kasan trying to access that ? Isn't kasan supposed to not check stuff in vmalloc area ?
>>
>> It tries to poison global variables in modules. If module is in vmalloc, than it will try to poison vmalloc.
>> Given that the vmalloc area is not so big on 32bits, the easiest solution is to cover all vmalloc with RW shadow.
>>
>
> Euh ... Not so big ?
>
> Memory: 96448K/131072K available (8016K kernel code, 1680K rwdata
> , 2720K rodata, 624K init, 4678K bss, 34624K reserved, 0K cma-reserved)
> Kernel virtual memory layout:
> * 0xffefc000..0xffffc000 : fixmap
> * 0xf7c00000..0xffc00000 : kasan shadow mem
> * 0xf7a00000..0xf7c00000 : consistent mem
> * 0xf7a00000..0xf7a00000 : early ioremap
> * 0xc9000000..0xf7a00000 : vmalloc & ioremap
>
> Here, vmalloc area size 0x2ea00000, that is 746Mbytes. Shadow for this would be 93Mbytes and we are already using 16Mbytes to shadow the linear memory area .... this poor board has 128Mbytes RAM in total.
>
> So another solution is needed.
>
Ok.
As a temporary workaround your can make __asan_register_globals() to skip globals in vmalloc().
Obviously it means that out-of-bounds accesses to in modules will be missed.
Non temporary solution would making kasan to fully support vmalloc, i.e. remove RO shadow and allocate/free shadow on vmalloc()/vfree().
But this feels like separate task, out of scope of this patch set.
It is also possible to follow some other arches - dedicate separate address range for modules, allocate/free shadow in module_alloc/free.
But it doesn't seem worthy to implement this only for the sake of kasan, since vmalloc support needs to be done anyway.
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v5 3/3] powerpc/32: Add KASAN support
[not found] ` <3429fe33b68206ecc2a725a740937bbaef2d1ac8.1549935251.git.christophe.leroy@c-s.fr>
2019-02-14 22:04 ` [PATCH v5 3/3] powerpc/32: Add KASAN support Daniel Axtens
@ 2019-02-18 9:27 ` Michael Ellerman
2019-02-19 18:03 ` Christophe Leroy
1 sibling, 1 reply; 7+ messages in thread
From: Michael Ellerman @ 2019-02-18 9:27 UTC (permalink / raw)
To: Christophe Leroy, Benjamin Herrenschmidt, Paul Mackerras,
Nicholas Piggin, Aneesh Kumar K.V, Andrey Ryabinin,
Alexander Potapenko, Dmitry Vyukov, Daniel Axtens
Cc: linux-kernel, linuxppc-dev, kasan-dev, linux-mm
Christophe Leroy <christophe.leroy@c-s.fr> writes:
> diff --git a/arch/powerpc/include/asm/ppc_asm.h b/arch/powerpc/include/asm/ppc_asm.h
> index e0637730a8e7..dba2c1038363 100644
> --- a/arch/powerpc/include/asm/ppc_asm.h
> +++ b/arch/powerpc/include/asm/ppc_asm.h
> @@ -251,6 +251,10 @@ GLUE(.,name):
>
> #define _GLOBAL_TOC(name) _GLOBAL(name)
>
> +#define KASAN_OVERRIDE(x, y) \
> + .weak x; \
> + .set x, y
> +
Can you add a comment describing what that does and why?
> diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
> index 879b36602748..fc4c42262694 100644
> --- a/arch/powerpc/kernel/Makefile
> +++ b/arch/powerpc/kernel/Makefile
> @@ -16,8 +16,9 @@ CFLAGS_prom_init.o += -fPIC
> CFLAGS_btext.o += -fPIC
> endif
>
> -CFLAGS_cputable.o += $(DISABLE_LATENT_ENTROPY_PLUGIN)
> -CFLAGS_prom_init.o += $(DISABLE_LATENT_ENTROPY_PLUGIN)
> +CFLAGS_early_32.o += -DDISABLE_BRANCH_PROFILING
> +CFLAGS_cputable.o += $(DISABLE_LATENT_ENTROPY_PLUGIN) -DDISABLE_BRANCH_PROFILING
> +CFLAGS_prom_init.o += $(DISABLE_LATENT_ENTROPY_PLUGIN) -DDISABLE_BRANCH_PROFILING
Why do we need to disable branch profiling now?
I'd probably be happier if all the CFLAGS changes were done in a leadup
patch to make them more obvious.
> diff --git a/arch/powerpc/kernel/prom_init_check.sh b/arch/powerpc/kernel/prom_init_check.sh
> index 667df97d2595..da6bb16e0876 100644
> --- a/arch/powerpc/kernel/prom_init_check.sh
> +++ b/arch/powerpc/kernel/prom_init_check.sh
> @@ -16,8 +16,16 @@
> # If you really need to reference something from prom_init.o add
> # it to the list below:
>
> +grep CONFIG_KASAN=y .config >/dev/null
Just to be safe "^CONFIG_KASAN=y$" ?
> +if [ $? -eq 0 ]
> +then
> + MEMFCT="__memcpy __memset"
> +else
> + MEMFCT="memcpy memset"
> +fi
MEM_FUNCS ?
> diff --git a/arch/powerpc/lib/Makefile b/arch/powerpc/lib/Makefile
> index 3bf9fc6fd36c..ce8d4a9f810a 100644
> --- a/arch/powerpc/lib/Makefile
> +++ b/arch/powerpc/lib/Makefile
> @@ -8,6 +8,14 @@ ccflags-$(CONFIG_PPC64) := $(NO_MINIMAL_TOC)
> CFLAGS_REMOVE_code-patching.o = $(CC_FLAGS_FTRACE)
> CFLAGS_REMOVE_feature-fixups.o = $(CC_FLAGS_FTRACE)
>
> +KASAN_SANITIZE_code-patching.o := n
> +KASAN_SANITIZE_feature-fixups.o := n
> +
> +ifdef CONFIG_KASAN
> +CFLAGS_code-patching.o += -DDISABLE_BRANCH_PROFILING
> +CFLAGS_feature-fixups.o += -DDISABLE_BRANCH_PROFILING
> +endif
There's that branch profiling again, though here it's only if KASAN is enabled.
> diff --git a/arch/powerpc/mm/kasan_init.c b/arch/powerpc/mm/kasan_init.c
> new file mode 100644
> index 000000000000..bd8e0a263e12
> --- /dev/null
> +++ b/arch/powerpc/mm/kasan_init.c
> @@ -0,0 +1,114 @@
> +// 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>
> +
> +void __init kasan_early_init(void)
> +{
> + unsigned long addr = KASAN_SHADOW_START;
> + unsigned long end = KASAN_SHADOW_END;
> + unsigned long next;
> + pmd_t *pmd = pmd_offset(pud_offset(pgd_offset_k(addr), addr), addr);
Can none of those fail?
cheers
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH v5 3/3] powerpc/32: Add KASAN support
2019-02-18 9:27 ` Michael Ellerman
@ 2019-02-19 18:03 ` Christophe Leroy
0 siblings, 0 replies; 7+ messages in thread
From: Christophe Leroy @ 2019-02-19 18:03 UTC (permalink / raw)
To: Michael Ellerman, Benjamin Herrenschmidt, Paul Mackerras,
Nicholas Piggin, Aneesh Kumar K.V, Andrey Ryabinin,
Alexander Potapenko, Dmitry Vyukov, Daniel Axtens
Cc: linux-kernel, linuxppc-dev, kasan-dev, linux-mm
Le 18/02/2019 à 10:27, Michael Ellerman a écrit :
> Christophe Leroy <christophe.leroy@c-s.fr> writes:
>
>> diff --git a/arch/powerpc/include/asm/ppc_asm.h b/arch/powerpc/include/asm/ppc_asm.h
>> index e0637730a8e7..dba2c1038363 100644
>> --- a/arch/powerpc/include/asm/ppc_asm.h
>> +++ b/arch/powerpc/include/asm/ppc_asm.h
>> @@ -251,6 +251,10 @@ GLUE(.,name):
>>
>> #define _GLOBAL_TOC(name) _GLOBAL(name)
>>
>> +#define KASAN_OVERRIDE(x, y) \
>> + .weak x; \
>> + .set x, y
>> +
>
> Can you add a comment describing what that does and why?
It's gone. Hope the new approach is more clear. It's now in a dedicated
patch.
>
>> diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
>> index 879b36602748..fc4c42262694 100644
>> --- a/arch/powerpc/kernel/Makefile
>> +++ b/arch/powerpc/kernel/Makefile
>> @@ -16,8 +16,9 @@ CFLAGS_prom_init.o += -fPIC
>> CFLAGS_btext.o += -fPIC
>> endif
>>
>> -CFLAGS_cputable.o += $(DISABLE_LATENT_ENTROPY_PLUGIN)
>> -CFLAGS_prom_init.o += $(DISABLE_LATENT_ENTROPY_PLUGIN)
>> +CFLAGS_early_32.o += -DDISABLE_BRANCH_PROFILING
>> +CFLAGS_cputable.o += $(DISABLE_LATENT_ENTROPY_PLUGIN) -DDISABLE_BRANCH_PROFILING
>> +CFLAGS_prom_init.o += $(DISABLE_LATENT_ENTROPY_PLUGIN) -DDISABLE_BRANCH_PROFILING
>
> Why do we need to disable branch profiling now?
Recommended by Andrey, see https://patchwork.ozlabs.org/patch/1023887/
Maybe it should be only when KASAN is active ? For prom_init it should
probably be all the time, for the others I don't know. Can't remember
why I did it that way.
>
> I'd probably be happier if all the CFLAGS changes were done in a leadup
> patch to make them more obvious.
Oops, I forgot to read your mail entirely before sending out v6. Indeed
I only read first part. Anyway, that's probably not the last run.
>
>> diff --git a/arch/powerpc/kernel/prom_init_check.sh b/arch/powerpc/kernel/prom_init_check.sh
>> index 667df97d2595..da6bb16e0876 100644
>> --- a/arch/powerpc/kernel/prom_init_check.sh
>> +++ b/arch/powerpc/kernel/prom_init_check.sh
>> @@ -16,8 +16,16 @@
>> # If you really need to reference something from prom_init.o add
>> # it to the list below:
>>
>> +grep CONFIG_KASAN=y .config >/dev/null
>
> Just to be safe "^CONFIG_KASAN=y$" ?
ok
>
>> +if [ $? -eq 0 ]
>> +then
>> + MEMFCT="__memcpy __memset"
>> +else
>> + MEMFCT="memcpy memset"
>> +fi
>
> MEM_FUNCS ?
Yes, I change it now before I forget.
>
>> diff --git a/arch/powerpc/lib/Makefile b/arch/powerpc/lib/Makefile
>> index 3bf9fc6fd36c..ce8d4a9f810a 100644
>> --- a/arch/powerpc/lib/Makefile
>> +++ b/arch/powerpc/lib/Makefile
>> @@ -8,6 +8,14 @@ ccflags-$(CONFIG_PPC64) := $(NO_MINIMAL_TOC)
>> CFLAGS_REMOVE_code-patching.o = $(CC_FLAGS_FTRACE)
>> CFLAGS_REMOVE_feature-fixups.o = $(CC_FLAGS_FTRACE)
>>
>> +KASAN_SANITIZE_code-patching.o := n
>> +KASAN_SANITIZE_feature-fixups.o := n
>> +
>> +ifdef CONFIG_KASAN
>> +CFLAGS_code-patching.o += -DDISABLE_BRANCH_PROFILING
>> +CFLAGS_feature-fixups.o += -DDISABLE_BRANCH_PROFILING
>> +endif
>
> There's that branch profiling again, though here it's only if KASAN is enabled.
>
>> diff --git a/arch/powerpc/mm/kasan_init.c b/arch/powerpc/mm/kasan_init.c
>> new file mode 100644
>> index 000000000000..bd8e0a263e12
>> --- /dev/null
>> +++ b/arch/powerpc/mm/kasan_init.c
>> @@ -0,0 +1,114 @@
>> +// 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>
>> +
>> +void __init kasan_early_init(void)
>> +{
>> + unsigned long addr = KASAN_SHADOW_START;
>> + unsigned long end = KASAN_SHADOW_END;
>> + unsigned long next;
>> + pmd_t *pmd = pmd_offset(pud_offset(pgd_offset_k(addr), addr), addr);
>
> Can none of those fail?
map_kernel_page() in pgtable_32.c does exactly the same.
pud_offset() and pmd_offset() are no-ops and only serve as type
modifiers, so pmd will get the value returned by pgd_offset_k() which
should always be valid unless init_mm->pgd is bad.
Christophe
>
>
> cheers
>
^ permalink raw reply [flat|nested] 7+ messages in thread
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2019-02-14 22:04 ` [PATCH v5 3/3] powerpc/32: Add KASAN support Daniel Axtens
2019-02-15 8:41 ` Christophe Leroy
2019-02-15 10:01 ` Andrey Ryabinin
2019-02-15 10:10 ` Christophe Leroy
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