| /* |
| * This file contains some kasan initialization code. |
| * |
| * Copyright (c) 2015 Samsung Electronics Co., Ltd. |
| * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com> |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License version 2 as |
| * published by the Free Software Foundation. |
| * |
| */ |
| |
| #include <linux/bootmem.h> |
| #include <linux/init.h> |
| #include <linux/kasan.h> |
| #include <linux/kernel.h> |
| #include <linux/memblock.h> |
| #include <linux/mm.h> |
| #include <linux/pfn.h> |
| #include <linux/slab.h> |
| |
| #include <asm/page.h> |
| #include <asm/pgalloc.h> |
| |
| #include "kasan.h" |
| |
| /* |
| * This page serves two purposes: |
| * - It used as early shadow memory. The entire shadow region populated |
| * with this page, before we will be able to setup normal shadow memory. |
| * - Latter it reused it as zero shadow to cover large ranges of memory |
| * that allowed to access, but not handled by kasan (vmalloc/vmemmap ...). |
| */ |
| unsigned char kasan_zero_page[PAGE_SIZE] __page_aligned_bss; |
| |
| #if CONFIG_PGTABLE_LEVELS > 4 |
| p4d_t kasan_zero_p4d[MAX_PTRS_PER_P4D] __page_aligned_bss; |
| static inline bool kasan_p4d_table(pgd_t pgd) |
| { |
| return pgd_page(pgd) == virt_to_page(lm_alias(kasan_zero_p4d)); |
| } |
| #else |
| static inline bool kasan_p4d_table(pgd_t pgd) |
| { |
| return 0; |
| } |
| #endif |
| #if CONFIG_PGTABLE_LEVELS > 3 |
| pud_t kasan_zero_pud[PTRS_PER_PUD] __page_aligned_bss; |
| static inline bool kasan_pud_table(p4d_t p4d) |
| { |
| return p4d_page(p4d) == virt_to_page(lm_alias(kasan_zero_pud)); |
| } |
| #else |
| static inline bool kasan_pud_table(p4d_t p4d) |
| { |
| return 0; |
| } |
| #endif |
| #if CONFIG_PGTABLE_LEVELS > 2 |
| pmd_t kasan_zero_pmd[PTRS_PER_PMD] __page_aligned_bss; |
| static inline bool kasan_pmd_table(pud_t pud) |
| { |
| return pud_page(pud) == virt_to_page(lm_alias(kasan_zero_pmd)); |
| } |
| #else |
| static inline bool kasan_pmd_table(pud_t pud) |
| { |
| return 0; |
| } |
| #endif |
| pte_t kasan_zero_pte[PTRS_PER_PTE] __page_aligned_bss; |
| |
| static inline bool kasan_pte_table(pmd_t pmd) |
| { |
| return pmd_page(pmd) == virt_to_page(lm_alias(kasan_zero_pte)); |
| } |
| |
| static inline bool kasan_zero_page_entry(pte_t pte) |
| { |
| return pte_page(pte) == virt_to_page(lm_alias(kasan_zero_page)); |
| } |
| |
| static __init void *early_alloc(size_t size, int node) |
| { |
| return memblock_virt_alloc_try_nid(size, size, __pa(MAX_DMA_ADDRESS), |
| BOOTMEM_ALLOC_ACCESSIBLE, node); |
| } |
| |
| static void __ref zero_pte_populate(pmd_t *pmd, unsigned long addr, |
| unsigned long end) |
| { |
| pte_t *pte = pte_offset_kernel(pmd, addr); |
| pte_t zero_pte; |
| |
| zero_pte = pfn_pte(PFN_DOWN(__pa_symbol(kasan_zero_page)), PAGE_KERNEL); |
| zero_pte = pte_wrprotect(zero_pte); |
| |
| while (addr + PAGE_SIZE <= end) { |
| set_pte_at(&init_mm, addr, pte, zero_pte); |
| addr += PAGE_SIZE; |
| pte = pte_offset_kernel(pmd, addr); |
| } |
| } |
| |
| static int __ref zero_pmd_populate(pud_t *pud, unsigned long addr, |
| unsigned long end) |
| { |
| pmd_t *pmd = pmd_offset(pud, addr); |
| unsigned long next; |
| |
| do { |
| next = pmd_addr_end(addr, end); |
| |
| if (IS_ALIGNED(addr, PMD_SIZE) && end - addr >= PMD_SIZE) { |
| pmd_populate_kernel(&init_mm, pmd, lm_alias(kasan_zero_pte)); |
| continue; |
| } |
| |
| if (pmd_none(*pmd)) { |
| pte_t *p; |
| |
| if (slab_is_available()) |
| p = pte_alloc_one_kernel(&init_mm, addr); |
| else |
| p = early_alloc(PAGE_SIZE, NUMA_NO_NODE); |
| if (!p) |
| return -ENOMEM; |
| |
| pmd_populate_kernel(&init_mm, pmd, p); |
| } |
| zero_pte_populate(pmd, addr, next); |
| } while (pmd++, addr = next, addr != end); |
| |
| return 0; |
| } |
| |
| static int __ref zero_pud_populate(p4d_t *p4d, unsigned long addr, |
| unsigned long end) |
| { |
| pud_t *pud = pud_offset(p4d, addr); |
| unsigned long next; |
| |
| do { |
| next = pud_addr_end(addr, end); |
| if (IS_ALIGNED(addr, PUD_SIZE) && end - addr >= PUD_SIZE) { |
| pmd_t *pmd; |
| |
| pud_populate(&init_mm, pud, lm_alias(kasan_zero_pmd)); |
| pmd = pmd_offset(pud, addr); |
| pmd_populate_kernel(&init_mm, pmd, lm_alias(kasan_zero_pte)); |
| continue; |
| } |
| |
| if (pud_none(*pud)) { |
| pmd_t *p; |
| |
| if (slab_is_available()) { |
| p = pmd_alloc(&init_mm, pud, addr); |
| if (!p) |
| return -ENOMEM; |
| } else { |
| pud_populate(&init_mm, pud, |
| early_alloc(PAGE_SIZE, NUMA_NO_NODE)); |
| } |
| } |
| zero_pmd_populate(pud, addr, next); |
| } while (pud++, addr = next, addr != end); |
| |
| return 0; |
| } |
| |
| static int __ref zero_p4d_populate(pgd_t *pgd, unsigned long addr, |
| unsigned long end) |
| { |
| p4d_t *p4d = p4d_offset(pgd, addr); |
| unsigned long next; |
| |
| do { |
| next = p4d_addr_end(addr, end); |
| if (IS_ALIGNED(addr, P4D_SIZE) && end - addr >= P4D_SIZE) { |
| pud_t *pud; |
| pmd_t *pmd; |
| |
| p4d_populate(&init_mm, p4d, lm_alias(kasan_zero_pud)); |
| pud = pud_offset(p4d, addr); |
| pud_populate(&init_mm, pud, lm_alias(kasan_zero_pmd)); |
| pmd = pmd_offset(pud, addr); |
| pmd_populate_kernel(&init_mm, pmd, |
| lm_alias(kasan_zero_pte)); |
| continue; |
| } |
| |
| if (p4d_none(*p4d)) { |
| pud_t *p; |
| |
| if (slab_is_available()) { |
| p = pud_alloc(&init_mm, p4d, addr); |
| if (!p) |
| return -ENOMEM; |
| } else { |
| p4d_populate(&init_mm, p4d, |
| early_alloc(PAGE_SIZE, NUMA_NO_NODE)); |
| } |
| } |
| zero_pud_populate(p4d, addr, next); |
| } while (p4d++, addr = next, addr != end); |
| |
| return 0; |
| } |
| |
| /** |
| * kasan_populate_zero_shadow - populate shadow memory region with |
| * kasan_zero_page |
| * @shadow_start - start of the memory range to populate |
| * @shadow_end - end of the memory range to populate |
| */ |
| int __ref kasan_populate_zero_shadow(const void *shadow_start, |
| const void *shadow_end) |
| { |
| unsigned long addr = (unsigned long)shadow_start; |
| unsigned long end = (unsigned long)shadow_end; |
| pgd_t *pgd = pgd_offset_k(addr); |
| unsigned long next; |
| |
| do { |
| next = pgd_addr_end(addr, end); |
| |
| if (IS_ALIGNED(addr, PGDIR_SIZE) && end - addr >= PGDIR_SIZE) { |
| p4d_t *p4d; |
| pud_t *pud; |
| pmd_t *pmd; |
| |
| /* |
| * kasan_zero_pud should be populated with pmds |
| * at this moment. |
| * [pud,pmd]_populate*() below needed only for |
| * 3,2 - level page tables where we don't have |
| * puds,pmds, so pgd_populate(), pud_populate() |
| * is noops. |
| * |
| * The ifndef is required to avoid build breakage. |
| * |
| * With 5level-fixup.h, pgd_populate() is not nop and |
| * we reference kasan_zero_p4d. It's not defined |
| * unless 5-level paging enabled. |
| * |
| * The ifndef can be dropped once all KASAN-enabled |
| * architectures will switch to pgtable-nop4d.h. |
| */ |
| #ifndef __ARCH_HAS_5LEVEL_HACK |
| pgd_populate(&init_mm, pgd, lm_alias(kasan_zero_p4d)); |
| #endif |
| p4d = p4d_offset(pgd, addr); |
| p4d_populate(&init_mm, p4d, lm_alias(kasan_zero_pud)); |
| pud = pud_offset(p4d, addr); |
| pud_populate(&init_mm, pud, lm_alias(kasan_zero_pmd)); |
| pmd = pmd_offset(pud, addr); |
| pmd_populate_kernel(&init_mm, pmd, lm_alias(kasan_zero_pte)); |
| continue; |
| } |
| |
| if (pgd_none(*pgd)) { |
| p4d_t *p; |
| |
| if (slab_is_available()) { |
| p = p4d_alloc(&init_mm, pgd, addr); |
| if (!p) |
| return -ENOMEM; |
| } else { |
| pgd_populate(&init_mm, pgd, |
| early_alloc(PAGE_SIZE, NUMA_NO_NODE)); |
| } |
| } |
| zero_p4d_populate(pgd, addr, next); |
| } while (pgd++, addr = next, addr != end); |
| |
| return 0; |
| } |
| |
| static void kasan_free_pte(pte_t *pte_start, pmd_t *pmd) |
| { |
| pte_t *pte; |
| int i; |
| |
| for (i = 0; i < PTRS_PER_PTE; i++) { |
| pte = pte_start + i; |
| if (!pte_none(*pte)) |
| return; |
| } |
| |
| pte_free_kernel(&init_mm, (pte_t *)page_to_virt(pmd_page(*pmd))); |
| pmd_clear(pmd); |
| } |
| |
| static void kasan_free_pmd(pmd_t *pmd_start, pud_t *pud) |
| { |
| pmd_t *pmd; |
| int i; |
| |
| for (i = 0; i < PTRS_PER_PMD; i++) { |
| pmd = pmd_start + i; |
| if (!pmd_none(*pmd)) |
| return; |
| } |
| |
| pmd_free(&init_mm, (pmd_t *)page_to_virt(pud_page(*pud))); |
| pud_clear(pud); |
| } |
| |
| static void kasan_free_pud(pud_t *pud_start, p4d_t *p4d) |
| { |
| pud_t *pud; |
| int i; |
| |
| for (i = 0; i < PTRS_PER_PUD; i++) { |
| pud = pud_start + i; |
| if (!pud_none(*pud)) |
| return; |
| } |
| |
| pud_free(&init_mm, (pud_t *)page_to_virt(p4d_page(*p4d))); |
| p4d_clear(p4d); |
| } |
| |
| static void kasan_free_p4d(p4d_t *p4d_start, pgd_t *pgd) |
| { |
| p4d_t *p4d; |
| int i; |
| |
| for (i = 0; i < PTRS_PER_P4D; i++) { |
| p4d = p4d_start + i; |
| if (!p4d_none(*p4d)) |
| return; |
| } |
| |
| p4d_free(&init_mm, (p4d_t *)page_to_virt(pgd_page(*pgd))); |
| pgd_clear(pgd); |
| } |
| |
| static void kasan_remove_pte_table(pte_t *pte, unsigned long addr, |
| unsigned long end) |
| { |
| unsigned long next; |
| |
| for (; addr < end; addr = next, pte++) { |
| next = (addr + PAGE_SIZE) & PAGE_MASK; |
| if (next > end) |
| next = end; |
| |
| if (!pte_present(*pte)) |
| continue; |
| |
| if (WARN_ON(!kasan_zero_page_entry(*pte))) |
| continue; |
| pte_clear(&init_mm, addr, pte); |
| } |
| } |
| |
| static void kasan_remove_pmd_table(pmd_t *pmd, unsigned long addr, |
| unsigned long end) |
| { |
| unsigned long next; |
| |
| for (; addr < end; addr = next, pmd++) { |
| pte_t *pte; |
| |
| next = pmd_addr_end(addr, end); |
| |
| if (!pmd_present(*pmd)) |
| continue; |
| |
| if (kasan_pte_table(*pmd)) { |
| if (IS_ALIGNED(addr, PMD_SIZE) && |
| IS_ALIGNED(next, PMD_SIZE)) { |
| pmd_clear(pmd); |
| continue; |
| } |
| } |
| pte = pte_offset_kernel(pmd, addr); |
| kasan_remove_pte_table(pte, addr, next); |
| kasan_free_pte(pte_offset_kernel(pmd, 0), pmd); |
| } |
| } |
| |
| static void kasan_remove_pud_table(pud_t *pud, unsigned long addr, |
| unsigned long end) |
| { |
| unsigned long next; |
| |
| for (; addr < end; addr = next, pud++) { |
| pmd_t *pmd, *pmd_base; |
| |
| next = pud_addr_end(addr, end); |
| |
| if (!pud_present(*pud)) |
| continue; |
| |
| if (kasan_pmd_table(*pud)) { |
| if (IS_ALIGNED(addr, PUD_SIZE) && |
| IS_ALIGNED(next, PUD_SIZE)) { |
| pud_clear(pud); |
| continue; |
| } |
| } |
| pmd = pmd_offset(pud, addr); |
| pmd_base = pmd_offset(pud, 0); |
| kasan_remove_pmd_table(pmd, addr, next); |
| kasan_free_pmd(pmd_base, pud); |
| } |
| } |
| |
| static void kasan_remove_p4d_table(p4d_t *p4d, unsigned long addr, |
| unsigned long end) |
| { |
| unsigned long next; |
| |
| for (; addr < end; addr = next, p4d++) { |
| pud_t *pud; |
| |
| next = p4d_addr_end(addr, end); |
| |
| if (!p4d_present(*p4d)) |
| continue; |
| |
| if (kasan_pud_table(*p4d)) { |
| if (IS_ALIGNED(addr, P4D_SIZE) && |
| IS_ALIGNED(next, P4D_SIZE)) { |
| p4d_clear(p4d); |
| continue; |
| } |
| } |
| pud = pud_offset(p4d, addr); |
| kasan_remove_pud_table(pud, addr, next); |
| kasan_free_pud(pud_offset(p4d, 0), p4d); |
| } |
| } |
| |
| void kasan_remove_zero_shadow(void *start, unsigned long size) |
| { |
| unsigned long addr, end, next; |
| pgd_t *pgd; |
| |
| addr = (unsigned long)kasan_mem_to_shadow(start); |
| end = addr + (size >> KASAN_SHADOW_SCALE_SHIFT); |
| |
| if (WARN_ON((unsigned long)start % |
| (KASAN_SHADOW_SCALE_SIZE * PAGE_SIZE)) || |
| WARN_ON(size % (KASAN_SHADOW_SCALE_SIZE * PAGE_SIZE))) |
| return; |
| |
| for (; addr < end; addr = next) { |
| p4d_t *p4d; |
| |
| next = pgd_addr_end(addr, end); |
| |
| pgd = pgd_offset_k(addr); |
| if (!pgd_present(*pgd)) |
| continue; |
| |
| if (kasan_p4d_table(*pgd)) { |
| if (IS_ALIGNED(addr, PGDIR_SIZE) && |
| IS_ALIGNED(next, PGDIR_SIZE)) { |
| pgd_clear(pgd); |
| continue; |
| } |
| } |
| |
| p4d = p4d_offset(pgd, addr); |
| kasan_remove_p4d_table(p4d, addr, next); |
| kasan_free_p4d(p4d_offset(pgd, 0), pgd); |
| } |
| } |
| |
| int kasan_add_zero_shadow(void *start, unsigned long size) |
| { |
| int ret; |
| void *shadow_start, *shadow_end; |
| |
| shadow_start = kasan_mem_to_shadow(start); |
| shadow_end = shadow_start + (size >> KASAN_SHADOW_SCALE_SHIFT); |
| |
| if (WARN_ON((unsigned long)start % |
| (KASAN_SHADOW_SCALE_SIZE * PAGE_SIZE)) || |
| WARN_ON(size % (KASAN_SHADOW_SCALE_SIZE * PAGE_SIZE))) |
| return -EINVAL; |
| |
| ret = kasan_populate_zero_shadow(shadow_start, shadow_end); |
| if (ret) |
| kasan_remove_zero_shadow(start, size); |
| return ret; |
| } |