From 8ad8b72721d0f07fa02dbe71f901743f9c71c8e6 Mon Sep 17 00:00:00 2001 From: Nick Hu Date: Mon, 6 Jan 2020 10:38:32 -0800 Subject: [PATCH] riscv: Add KASAN support This patch ports the feature Kernel Address SANitizer (KASAN). Note: The start address of shadow memory is at the beginning of kernel space, which is 2^64 - (2^39 / 2) in SV39. The size of the kernel space is 2^38 bytes so the size of shadow memory should be 2^38 / 8. Thus, the shadow memory would not overlap with the fixmap area. There are currently two limitations in this port, 1. RV64 only: KASAN need large address space for extra shadow memory region. 2. KASAN can't debug the modules since the modules are allocated in VMALLOC area. We mapped the shadow memory, which corresponding to VMALLOC area, to the kasan_early_shadow_page because we don't have enough physical space for all the shadow memory corresponding to VMALLOC area. Signed-off-by: Nick Hu Reported-by: Greentime Hu Signed-off-by: Palmer Dabbelt --- arch/riscv/Kconfig | 1 + arch/riscv/include/asm/kasan.h | 27 ++++++++ arch/riscv/include/asm/pgtable-64.h | 5 ++ arch/riscv/include/asm/string.h | 9 +++ arch/riscv/kernel/head.S | 3 + arch/riscv/kernel/riscv_ksyms.c | 2 + arch/riscv/kernel/setup.c | 5 ++ arch/riscv/kernel/vmlinux.lds.S | 1 + arch/riscv/lib/memcpy.S | 5 +- arch/riscv/lib/memset.S | 5 +- arch/riscv/mm/Makefile | 6 ++ arch/riscv/mm/kasan_init.c | 104 ++++++++++++++++++++++++++++ 12 files changed, 169 insertions(+), 4 deletions(-) create mode 100644 arch/riscv/include/asm/kasan.h create mode 100644 arch/riscv/mm/kasan_init.c diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index fa7dc03459e7..d1d77c6d6721 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -66,6 +66,7 @@ config RISCV select HAVE_ARCH_MMAP_RND_BITS if MMU select ARCH_HAS_GCOV_PROFILE_ALL select HAVE_COPY_THREAD_TLS + select HAVE_ARCH_KASAN if MMU && 64BIT config ARCH_MMAP_RND_BITS_MIN default 18 if 64BIT diff --git a/arch/riscv/include/asm/kasan.h b/arch/riscv/include/asm/kasan.h new file mode 100644 index 000000000000..eee6e6588b12 --- /dev/null +++ b/arch/riscv/include/asm/kasan.h @@ -0,0 +1,27 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* Copyright (C) 2019 Andes Technology Corporation */ + +#ifndef __ASM_KASAN_H +#define __ASM_KASAN_H + +#ifndef __ASSEMBLY__ + +#ifdef CONFIG_KASAN + +#include + +#define KASAN_SHADOW_SCALE_SHIFT 3 + +#define KASAN_SHADOW_SIZE (UL(1) << (38 - KASAN_SHADOW_SCALE_SHIFT)) +#define KASAN_SHADOW_START 0xffffffc000000000 /* 2^64 - 2^38 */ +#define KASAN_SHADOW_END (KASAN_SHADOW_START + KASAN_SHADOW_SIZE) + +#define KASAN_SHADOW_OFFSET (KASAN_SHADOW_END - (1ULL << \ + (64 - KASAN_SHADOW_SCALE_SHIFT))) + +void kasan_init(void); +asmlinkage void kasan_early_init(void); + +#endif +#endif +#endif /* __ASM_KASAN_H */ diff --git a/arch/riscv/include/asm/pgtable-64.h b/arch/riscv/include/asm/pgtable-64.h index 74630989006d..36e638d1dfe4 100644 --- a/arch/riscv/include/asm/pgtable-64.h +++ b/arch/riscv/include/asm/pgtable-64.h @@ -58,6 +58,11 @@ static inline unsigned long pud_page_vaddr(pud_t pud) return (unsigned long)pfn_to_virt(pud_val(pud) >> _PAGE_PFN_SHIFT); } +static inline struct page *pud_page(pud_t pud) +{ + return pfn_to_page(pud_val(pud) >> _PAGE_PFN_SHIFT); +} + #define pmd_index(addr) (((addr) >> PMD_SHIFT) & (PTRS_PER_PMD - 1)) static inline pmd_t *pmd_offset(pud_t *pud, unsigned long addr) diff --git a/arch/riscv/include/asm/string.h b/arch/riscv/include/asm/string.h index 1b5d44585962..924af13f8555 100644 --- a/arch/riscv/include/asm/string.h +++ b/arch/riscv/include/asm/string.h @@ -11,8 +11,17 @@ #define __HAVE_ARCH_MEMSET extern asmlinkage void *memset(void *, int, size_t); +extern asmlinkage void *__memset(void *, int, size_t); #define __HAVE_ARCH_MEMCPY extern asmlinkage void *memcpy(void *, const void *, size_t); +extern asmlinkage void *__memcpy(void *, const void *, size_t); +/* For those files which don't want to check by kasan. */ +#if defined(CONFIG_KASAN) && !defined(__SANITIZE_ADDRESS__) + +#define memcpy(dst, src, len) __memcpy(dst, src, len) +#define memset(s, c, n) __memset(s, c, n) + +#endif #endif /* _ASM_RISCV_STRING_H */ diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S index a4242be66966..271860fc2c3f 100644 --- a/arch/riscv/kernel/head.S +++ b/arch/riscv/kernel/head.S @@ -121,6 +121,9 @@ clear_bss_done: sw zero, TASK_TI_CPU(tp) la sp, init_thread_union + THREAD_SIZE +#ifdef CONFIG_KASAN + call kasan_early_init +#endif /* Start the kernel */ call parse_dtb tail start_kernel diff --git a/arch/riscv/kernel/riscv_ksyms.c b/arch/riscv/kernel/riscv_ksyms.c index 2a02b7eebee0..450492e1cb4e 100644 --- a/arch/riscv/kernel/riscv_ksyms.c +++ b/arch/riscv/kernel/riscv_ksyms.c @@ -11,3 +11,5 @@ */ EXPORT_SYMBOL(memset); EXPORT_SYMBOL(memcpy); +EXPORT_SYMBOL(__memset); +EXPORT_SYMBOL(__memcpy); diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c index 365ff8420bfe..22b671dbbcf1 100644 --- a/arch/riscv/kernel/setup.c +++ b/arch/riscv/kernel/setup.c @@ -24,6 +24,7 @@ #include #include #include +#include #include "head.h" @@ -74,6 +75,10 @@ void __init setup_arch(char **cmdline_p) swiotlb_init(1); #endif +#ifdef CONFIG_KASAN + kasan_init(); +#endif + #ifdef CONFIG_SMP setup_smp(); #endif diff --git a/arch/riscv/kernel/vmlinux.lds.S b/arch/riscv/kernel/vmlinux.lds.S index 12f42f96d46e..1e0193ded420 100644 --- a/arch/riscv/kernel/vmlinux.lds.S +++ b/arch/riscv/kernel/vmlinux.lds.S @@ -46,6 +46,7 @@ SECTIONS KPROBES_TEXT ENTRY_TEXT IRQENTRY_TEXT + SOFTIRQENTRY_TEXT *(.fixup) _etext = .; } diff --git a/arch/riscv/lib/memcpy.S b/arch/riscv/lib/memcpy.S index b4c477846e91..51ab716253fa 100644 --- a/arch/riscv/lib/memcpy.S +++ b/arch/riscv/lib/memcpy.S @@ -7,7 +7,8 @@ #include /* void *memcpy(void *, const void *, size_t) */ -ENTRY(memcpy) +ENTRY(__memcpy) +WEAK(memcpy) move t6, a0 /* Preserve return value */ /* Defer to byte-oriented copy for small sizes */ @@ -104,4 +105,4 @@ ENTRY(memcpy) bltu a1, a3, 5b 6: ret -END(memcpy) +END(__memcpy) diff --git a/arch/riscv/lib/memset.S b/arch/riscv/lib/memset.S index 5a7386b47175..34c5360c6705 100644 --- a/arch/riscv/lib/memset.S +++ b/arch/riscv/lib/memset.S @@ -8,7 +8,8 @@ #include /* void *memset(void *, int, size_t) */ -ENTRY(memset) +ENTRY(__memset) +WEAK(memset) move t0, a0 /* Preserve return value */ /* Defer to byte-oriented fill for small sizes */ @@ -109,4 +110,4 @@ ENTRY(memset) bltu t0, a3, 5b 6: ret -END(memset) +END(__memset) diff --git a/arch/riscv/mm/Makefile b/arch/riscv/mm/Makefile index a1bd95c8047a..670de7c1fd25 100644 --- a/arch/riscv/mm/Makefile +++ b/arch/riscv/mm/Makefile @@ -15,3 +15,9 @@ ifeq ($(CONFIG_MMU),y) obj-$(CONFIG_SMP) += tlbflush.o endif obj-$(CONFIG_HUGETLB_PAGE) += hugetlbpage.o +obj-$(CONFIG_KASAN) += kasan_init.o + +ifdef CONFIG_KASAN +KASAN_SANITIZE_kasan_init.o := n +KASAN_SANITIZE_init.o := n +endif diff --git a/arch/riscv/mm/kasan_init.c b/arch/riscv/mm/kasan_init.c new file mode 100644 index 000000000000..f0cc86040587 --- /dev/null +++ b/arch/riscv/mm/kasan_init.c @@ -0,0 +1,104 @@ +// SPDX-License-Identifier: GPL-2.0 +// Copyright (C) 2019 Andes Technology Corporation + +#include +#include +#include +#include +#include +#include +#include +#include + +extern pgd_t early_pg_dir[PTRS_PER_PGD]; +asmlinkage void __init kasan_early_init(void) +{ + uintptr_t i; + pgd_t *pgd = early_pg_dir + pgd_index(KASAN_SHADOW_START); + + for (i = 0; i < PTRS_PER_PTE; ++i) + set_pte(kasan_early_shadow_pte + i, + mk_pte(virt_to_page(kasan_early_shadow_page), + PAGE_KERNEL)); + + for (i = 0; i < PTRS_PER_PMD; ++i) + set_pmd(kasan_early_shadow_pmd + i, + pfn_pmd(PFN_DOWN(__pa((uintptr_t)kasan_early_shadow_pte)), + __pgprot(_PAGE_TABLE))); + + for (i = KASAN_SHADOW_START; i < KASAN_SHADOW_END; + i += PGDIR_SIZE, ++pgd) + set_pgd(pgd, + pfn_pgd(PFN_DOWN(__pa(((uintptr_t)kasan_early_shadow_pmd))), + __pgprot(_PAGE_TABLE))); + + /* init for swapper_pg_dir */ + pgd = pgd_offset_k(KASAN_SHADOW_START); + + for (i = KASAN_SHADOW_START; i < KASAN_SHADOW_END; + i += PGDIR_SIZE, ++pgd) + set_pgd(pgd, + pfn_pgd(PFN_DOWN(__pa(((uintptr_t)kasan_early_shadow_pmd))), + __pgprot(_PAGE_TABLE))); + + flush_tlb_all(); +} + +static void __init populate(void *start, void *end) +{ + unsigned long i; + unsigned long vaddr = (unsigned long)start & PAGE_MASK; + unsigned long vend = PAGE_ALIGN((unsigned long)end); + unsigned long n_pages = (vend - vaddr) / PAGE_SIZE; + unsigned long n_pmds = + (n_pages % PTRS_PER_PTE) ? n_pages / PTRS_PER_PTE + 1 : + n_pages / PTRS_PER_PTE; + pgd_t *pgd = pgd_offset_k(vaddr); + pmd_t *pmd = memblock_alloc(n_pmds * sizeof(pmd_t), PAGE_SIZE); + pte_t *pte = memblock_alloc(n_pages * sizeof(pte_t), PAGE_SIZE); + + for (i = 0; i < n_pages; i++) { + phys_addr_t phys = memblock_phys_alloc(PAGE_SIZE, PAGE_SIZE); + + set_pte(pte + i, pfn_pte(PHYS_PFN(phys), PAGE_KERNEL)); + } + + for (i = 0; i < n_pmds; ++pgd, i += PTRS_PER_PMD) + set_pgd(pgd, pfn_pgd(PFN_DOWN(__pa(((uintptr_t)(pmd + i)))), + __pgprot(_PAGE_TABLE))); + + for (i = 0; i < n_pages; ++pmd, i += PTRS_PER_PTE) + set_pmd(pmd, pfn_pmd(PFN_DOWN(__pa((uintptr_t)(pte + i))), + __pgprot(_PAGE_TABLE))); + + flush_tlb_all(); + memset(start, 0, end - start); +} + +void __init kasan_init(void) +{ + struct memblock_region *reg; + unsigned long i; + + kasan_populate_early_shadow((void *)KASAN_SHADOW_START, + (void *)kasan_mem_to_shadow((void *)VMALLOC_END)); + + for_each_memblock(memory, reg) { + void *start = (void *)__va(reg->base); + void *end = (void *)__va(reg->base + reg->size); + + if (start >= end) + break; + + populate(kasan_mem_to_shadow(start), + kasan_mem_to_shadow(end)); + }; + + for (i = 0; i < PTRS_PER_PTE; i++) + set_pte(&kasan_early_shadow_pte[i], + mk_pte(virt_to_page(kasan_early_shadow_page), + __pgprot(_PAGE_PRESENT | _PAGE_READ | _PAGE_ACCESSED))); + + memset(kasan_early_shadow_page, 0, PAGE_SIZE); + init_task.kasan_depth = 0; +}