From: Marco Elver <elver@xxxxxxxxxx> Subject: arm64, kfence: enable KFENCE for ARM64 Add architecture specific implementation details for KFENCE and enable KFENCE for the arm64 architecture. In particular, this implements the required interface in <asm/kfence.h>. KFENCE requires that attributes for pages from its memory pool can individually be set. Therefore, force the entire linear map to be mapped at page granularity. Doing so may result in extra memory allocated for page tables in case rodata=full is not set; however, currently CONFIG_RODATA_FULL_DEFAULT_ENABLED=y is the default, and the common case is therefore not affected by this change. [elver@xxxxxxxxxx: add missing copyright and description header] Link: https://lkml.kernel.org/r/20210118092159.145934-3-elver@xxxxxxxxxx Link: https://lkml.kernel.org/r/20201103175841.3495947-4-elver@xxxxxxxxxx Signed-off-by: Alexander Potapenko <glider@xxxxxxxxxx> Signed-off-by: Marco Elver <elver@xxxxxxxxxx> Reviewed-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx> Co-developed-by: Alexander Potapenko <glider@xxxxxxxxxx> Reviewed-by: Jann Horn <jannh@xxxxxxxxxx> Reviewed-by: Mark Rutland <mark.rutland@xxxxxxx> Cc: Andrey Konovalov <andreyknvl@xxxxxxxxxx> Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx> Cc: Andy Lutomirski <luto@xxxxxxxxxx> Cc: Borislav Petkov <bp@xxxxxxxxx> Cc: Catalin Marinas <catalin.marinas@xxxxxxx> Cc: Christopher Lameter <cl@xxxxxxxxx> Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx> Cc: David Rientjes <rientjes@xxxxxxxxxx> Cc: Eric Dumazet <edumazet@xxxxxxxxxx> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Cc: Hillf Danton <hdanton@xxxxxxxx> Cc: "H. Peter Anvin" <hpa@xxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: Joern Engel <joern@xxxxxxxxxxxxxxx> Cc: Jonathan Corbet <corbet@xxxxxxx> Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> Cc: Kees Cook <keescook@xxxxxxxxxxxx> Cc: Paul E. McKenney <paulmck@xxxxxxxxxx> Cc: Pekka Enberg <penberg@xxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: SeongJae Park <sjpark@xxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Vlastimil Babka <vbabka@xxxxxxx> Cc: Will Deacon <will@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- arch/arm64/Kconfig | 1 + arch/arm64/include/asm/kfence.h | 24 ++++++++++++++++++++++++ arch/arm64/mm/fault.c | 4 ++++ arch/arm64/mm/mmu.c | 8 +++++++- 4 files changed, 36 insertions(+), 1 deletion(-) --- /dev/null +++ a/arch/arm64/include/asm/kfence.h @@ -0,0 +1,24 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * arm64 KFENCE support. + * + * Copyright (C) 2020, Google LLC. + */ + +#ifndef __ASM_KFENCE_H +#define __ASM_KFENCE_H + +#include <asm/cacheflush.h> + +#define KFENCE_SKIP_ARCH_FAULT_HANDLER "el1_sync" + +static inline bool arch_kfence_init_pool(void) { return true; } + +static inline bool kfence_protect_page(unsigned long addr, bool protect) +{ + set_memory_valid(addr, 1, !protect); + + return true; +} + +#endif /* __ASM_KFENCE_H */ --- a/arch/arm64/Kconfig~arm64-kfence-enable-kfence-for-arm64 +++ a/arch/arm64/Kconfig @@ -140,6 +140,7 @@ config ARM64 select HAVE_ARCH_KASAN if !(ARM64_16K_PAGES && ARM64_VA_BITS_48) select HAVE_ARCH_KASAN_SW_TAGS if HAVE_ARCH_KASAN select HAVE_ARCH_KASAN_HW_TAGS if (HAVE_ARCH_KASAN && ARM64_MTE) + select HAVE_ARCH_KFENCE select HAVE_ARCH_KGDB select HAVE_ARCH_MMAP_RND_BITS select HAVE_ARCH_MMAP_RND_COMPAT_BITS if COMPAT --- a/arch/arm64/mm/fault.c~arm64-kfence-enable-kfence-for-arm64 +++ a/arch/arm64/mm/fault.c @@ -10,6 +10,7 @@ #include <linux/acpi.h> #include <linux/bitfield.h> #include <linux/extable.h> +#include <linux/kfence.h> #include <linux/signal.h> #include <linux/mm.h> #include <linux/hardirq.h> @@ -389,6 +390,9 @@ static void __do_kernel_fault(unsigned l } else if (addr < PAGE_SIZE) { msg = "NULL pointer dereference"; } else { + if (kfence_handle_page_fault(addr)) + return; + msg = "paging request"; } --- a/arch/arm64/mm/mmu.c~arm64-kfence-enable-kfence-for-arm64 +++ a/arch/arm64/mm/mmu.c @@ -1465,7 +1465,13 @@ int arch_add_memory(int nid, u64 start, int ret, flags = 0; VM_BUG_ON(!mhp_range_allowed(start, size, true)); - if (rodata_full || debug_pagealloc_enabled()) + + /* + * KFENCE requires linear map to be mapped at page granularity, so that + * it is possible to protect/unprotect single pages in the KFENCE pool. + */ + if (rodata_full || debug_pagealloc_enabled() || + IS_ENABLED(CONFIG_KFENCE)) flags = NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS; __create_pgd_mapping(swapper_pg_dir, start, __phys_to_virt(start), _
