diff options
Diffstat (limited to 'arch/arm/mm')
| -rw-r--r-- | arch/arm/mm/Makefile | 3 | ||||
| -rw-r--r-- | arch/arm/mm/kasan_init.c | 291 | ||||
| -rw-r--r-- | arch/arm/mm/pgd.c | 16 |
3 files changed, 309 insertions, 1 deletions
diff --git a/arch/arm/mm/Makefile b/arch/arm/mm/Makefile index 99699c32d8a5..4536159bc8fa 100644 --- a/arch/arm/mm/Makefile +++ b/arch/arm/mm/Makefile @@ -113,3 +113,6 @@ obj-$(CONFIG_CACHE_L2X0_PMU) += cache-l2x0-pmu.o obj-$(CONFIG_CACHE_XSC3L2) += cache-xsc3l2.o obj-$(CONFIG_CACHE_TAUROS2) += cache-tauros2.o obj-$(CONFIG_CACHE_UNIPHIER) += cache-uniphier.o + +KASAN_SANITIZE_kasan_init.o := n +obj-$(CONFIG_KASAN) += kasan_init.o diff --git a/arch/arm/mm/kasan_init.c b/arch/arm/mm/kasan_init.c new file mode 100644 index 000000000000..9c348042a724 --- /dev/null +++ b/arch/arm/mm/kasan_init.c @@ -0,0 +1,291 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * This file contains kasan initialization code for ARM. + * + * Copyright (c) 2018 Samsung Electronics Co., Ltd. + * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com> + * Author: Linus Walleij <linus.walleij@linaro.org> + */ + +#define pr_fmt(fmt) "kasan: " fmt +#include <linux/kasan.h> +#include <linux/kernel.h> +#include <linux/memblock.h> +#include <linux/sched/task.h> +#include <linux/start_kernel.h> +#include <linux/pgtable.h> +#include <asm/cputype.h> +#include <asm/highmem.h> +#include <asm/mach/map.h> +#include <asm/memory.h> +#include <asm/page.h> +#include <asm/pgalloc.h> +#include <asm/procinfo.h> +#include <asm/proc-fns.h> + +#include "mm.h" + +static pgd_t tmp_pgd_table[PTRS_PER_PGD] __initdata __aligned(PGD_SIZE); + +pmd_t tmp_pmd_table[PTRS_PER_PMD] __page_aligned_bss; + +static __init void *kasan_alloc_block(size_t size) +{ + return memblock_alloc_try_nid(size, size, __pa(MAX_DMA_ADDRESS), + MEMBLOCK_ALLOC_KASAN, NUMA_NO_NODE); +} + +static void __init kasan_pte_populate(pmd_t *pmdp, unsigned long addr, + unsigned long end, bool early) +{ + unsigned long next; + pte_t *ptep = pte_offset_kernel(pmdp, addr); + + do { + pte_t entry; + void *p; + + next = addr + PAGE_SIZE; + + if (!early) { + if (!pte_none(READ_ONCE(*ptep))) + continue; + + p = kasan_alloc_block(PAGE_SIZE); + if (!p) { + panic("%s failed to allocate shadow page for address 0x%lx\n", + __func__, addr); + return; + } + memset(p, KASAN_SHADOW_INIT, PAGE_SIZE); + entry = pfn_pte(virt_to_pfn(p), + __pgprot(pgprot_val(PAGE_KERNEL))); + } else if (pte_none(READ_ONCE(*ptep))) { + /* + * The early shadow memory is mapping all KASan + * operations to one and the same page in memory, + * "kasan_early_shadow_page" so that the instrumentation + * will work on a scratch area until we can set up the + * proper KASan shadow memory. + */ + entry = pfn_pte(virt_to_pfn(kasan_early_shadow_page), + __pgprot(_L_PTE_DEFAULT | L_PTE_DIRTY | L_PTE_XN)); + } else { + /* + * Early shadow mappings are PMD_SIZE aligned, so if the + * first entry is already set, they must all be set. + */ + return; + } + + set_pte_at(&init_mm, addr, ptep, entry); + } while (ptep++, addr = next, addr != end); +} + +/* + * The pmd (page middle directory) is only used on LPAE + */ +static void __init kasan_pmd_populate(pud_t *pudp, unsigned long addr, + unsigned long end, bool early) +{ + unsigned long next; + pmd_t *pmdp = pmd_offset(pudp, addr); + + do { + if (pmd_none(*pmdp)) { + /* + * We attempt to allocate a shadow block for the PMDs + * used by the PTEs for this address if it isn't already + * allocated. + */ + void *p = early ? kasan_early_shadow_pte : + kasan_alloc_block(PAGE_SIZE); + + if (!p) { + panic("%s failed to allocate shadow block for address 0x%lx\n", + __func__, addr); + return; + } + pmd_populate_kernel(&init_mm, pmdp, p); + flush_pmd_entry(pmdp); + } + + next = pmd_addr_end(addr, end); + kasan_pte_populate(pmdp, addr, next, early); + } while (pmdp++, addr = next, addr != end); +} + +static void __init kasan_pgd_populate(unsigned long addr, unsigned long end, + bool early) +{ + unsigned long next; + pgd_t *pgdp; + p4d_t *p4dp; + pud_t *pudp; + + pgdp = pgd_offset_k(addr); + + do { + /* + * Allocate and populate the shadow block of p4d folded into + * pud folded into pmd if it doesn't already exist + */ + if (!early && pgd_none(*pgdp)) { + void *p = kasan_alloc_block(PAGE_SIZE); + + if (!p) { + panic("%s failed to allocate shadow block for address 0x%lx\n", + __func__, addr); + return; + } + pgd_populate(&init_mm, pgdp, p); + } + + next = pgd_addr_end(addr, end); + /* + * We just immediately jump over the p4d and pud page + * directories since we believe ARM32 will never gain four + * nor five level page tables. + */ + p4dp = p4d_offset(pgdp, addr); + pudp = pud_offset(p4dp, addr); + + kasan_pmd_populate(pudp, addr, next, early); + } while (pgdp++, addr = next, addr != end); +} + +extern struct proc_info_list *lookup_processor_type(unsigned int); + +void __init kasan_early_init(void) +{ + struct proc_info_list *list; + + /* + * locate processor in the list of supported processor + * types. The linker builds this table for us from the + * entries in arch/arm/mm/proc-*.S + */ + list = lookup_processor_type(read_cpuid_id()); + if (list) { +#ifdef MULTI_CPU + processor = *list->proc; +#endif + } + + BUILD_BUG_ON((KASAN_SHADOW_END - (1UL << 29)) != KASAN_SHADOW_OFFSET); + /* + * We walk the page table and set all of the shadow memory to point + * to the scratch page. + */ + kasan_pgd_populate(KASAN_SHADOW_START, KASAN_SHADOW_END, true); +} + +static void __init clear_pgds(unsigned long start, + unsigned long end) +{ + for (; start && start < end; start += PMD_SIZE) + pmd_clear(pmd_off_k(start)); +} + +static int __init create_mapping(void *start, void *end) +{ + void *shadow_start, *shadow_end; + + shadow_start = kasan_mem_to_shadow(start); + shadow_end = kasan_mem_to_shadow(end); + + pr_info("Mapping kernel virtual memory block: %px-%px at shadow: %px-%px\n", + start, end, shadow_start, shadow_end); + + kasan_pgd_populate((unsigned long)shadow_start & PAGE_MASK, + PAGE_ALIGN((unsigned long)shadow_end), false); + return 0; +} + +void __init kasan_init(void) +{ + phys_addr_t pa_start, pa_end; + u64 i; + + /* + * We are going to perform proper setup of shadow memory. + * + * At first we should unmap early shadow (clear_pgds() call bellow). + * However, instrumented code can't execute without shadow memory. + * + * To keep the early shadow memory MMU tables around while setting up + * the proper shadow memory, we copy swapper_pg_dir (the initial page + * table) to tmp_pgd_table and use that to keep the early shadow memory + * mapped until the full shadow setup is finished. Then we swap back + * to the proper swapper_pg_dir. + */ + + memcpy(tmp_pgd_table, swapper_pg_dir, sizeof(tmp_pgd_table)); +#ifdef CONFIG_ARM_LPAE + /* We need to be in the same PGD or this won't work */ + BUILD_BUG_ON(pgd_index(KASAN_SHADOW_START) != + pgd_index(KASAN_SHADOW_END)); + memcpy(tmp_pmd_table, + pgd_page_vaddr(*pgd_offset_k(KASAN_SHADOW_START)), + sizeof(tmp_pmd_table)); + set_pgd(&tmp_pgd_table[pgd_index(KASAN_SHADOW_START)], + __pgd(__pa(tmp_pmd_table) | PMD_TYPE_TABLE | L_PGD_SWAPPER)); +#endif + cpu_switch_mm(tmp_pgd_table, &init_mm); + local_flush_tlb_all(); + + clear_pgds(KASAN_SHADOW_START, KASAN_SHADOW_END); + + kasan_populate_early_shadow(kasan_mem_to_shadow((void *)VMALLOC_START), + kasan_mem_to_shadow((void *)-1UL) + 1); + + for_each_mem_range(i, &pa_start, &pa_end) { + void *start = __va(pa_start); + void *end = __va(pa_end); + + /* Do not attempt to shadow highmem */ + if (pa_start >= arm_lowmem_limit) { + pr_info("Skip highmem block at %pa-%pa\n", &pa_start, &pa_end); + continue; + } + if (pa_end > arm_lowmem_limit) { + pr_info("Truncating shadow for memory block at %pa-%pa to lowmem region at %pa\n", + &pa_start, &pa_end, &arm_lowmem_limit); + end = __va(arm_lowmem_limit); + } + if (start >= end) { + pr_info("Skipping invalid memory block %pa-%pa (virtual %p-%p)\n", + &pa_start, &pa_end, start, end); + continue; + } + + create_mapping(start, end); + } + + /* + * 1. The module global variables are in MODULES_VADDR ~ MODULES_END, + * so we need to map this area. + * 2. PKMAP_BASE ~ PKMAP_BASE+PMD_SIZE's shadow and MODULES_VADDR + * ~ MODULES_END's shadow is in the same PMD_SIZE, so we can't + * use kasan_populate_zero_shadow. + */ + create_mapping((void *)MODULES_VADDR, (void *)(PKMAP_BASE + PMD_SIZE)); + + /* + * KAsan may reuse the contents of kasan_early_shadow_pte directly, so + * we should make sure that it maps the zero page read-only. + */ + for (i = 0; i < PTRS_PER_PTE; i++) + set_pte_at(&init_mm, KASAN_SHADOW_START + i*PAGE_SIZE, + &kasan_early_shadow_pte[i], + pfn_pte(virt_to_pfn(kasan_early_shadow_page), + __pgprot(pgprot_val(PAGE_KERNEL) + | L_PTE_RDONLY))); + + cpu_switch_mm(swapper_pg_dir, &init_mm); + local_flush_tlb_all(); + + memset(kasan_early_shadow_page, 0, PAGE_SIZE); + pr_info("Kernel address sanitizer initialized\n"); + init_task.kasan_depth = 0; +} diff --git a/arch/arm/mm/pgd.c b/arch/arm/mm/pgd.c index c5e1b27046a8..f8e9bc58a84f 100644 --- a/arch/arm/mm/pgd.c +++ b/arch/arm/mm/pgd.c @@ -66,7 +66,21 @@ pgd_t *pgd_alloc(struct mm_struct *mm) new_pmd = pmd_alloc(mm, new_pud, 0); if (!new_pmd) goto no_pmd; -#endif +#ifdef CONFIG_KASAN + /* + * Copy PMD table for KASAN shadow mappings. + */ + init_pgd = pgd_offset_k(TASK_SIZE); + init_p4d = p4d_offset(init_pgd, TASK_SIZE); + init_pud = pud_offset(init_p4d, TASK_SIZE); + init_pmd = pmd_offset(init_pud, TASK_SIZE); + new_pmd = pmd_offset(new_pud, TASK_SIZE); + memcpy(new_pmd, init_pmd, + (pmd_index(MODULES_VADDR) - pmd_index(TASK_SIZE)) + * sizeof(pmd_t)); + clean_dcache_area(new_pmd, PTRS_PER_PMD * sizeof(pmd_t)); +#endif /* CONFIG_KASAN */ +#endif /* CONFIG_LPAE */ if (!vectors_high()) { /* |