492 lines
11 KiB
C
492 lines
11 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* This file contains KASAN shadow initialization code.
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*
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* Copyright (c) 2015 Samsung Electronics Co., Ltd.
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* Author: Andrey Ryabinin <ryabinin.a.a@gmail.com>
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*/
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#include <linux/memblock.h>
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#include <linux/init.h>
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#include <linux/kasan.h>
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/pfn.h>
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#include <linux/slab.h>
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#include <asm/page.h>
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#include <asm/pgalloc.h>
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#include "kasan.h"
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/*
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* This page serves two purposes:
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* - It used as early shadow memory. The entire shadow region populated
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* with this page, before we will be able to setup normal shadow memory.
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* - Latter it reused it as zero shadow to cover large ranges of memory
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* that allowed to access, but not handled by kasan (vmalloc/vmemmap ...).
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*/
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unsigned char kasan_early_shadow_page[PAGE_SIZE] __page_aligned_bss;
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#if CONFIG_PGTABLE_LEVELS > 4
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p4d_t kasan_early_shadow_p4d[MAX_PTRS_PER_P4D] __page_aligned_bss;
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static inline bool kasan_p4d_table(pgd_t pgd)
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{
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return pgd_page(pgd) == virt_to_page(lm_alias(kasan_early_shadow_p4d));
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}
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#else
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static inline bool kasan_p4d_table(pgd_t pgd)
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{
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return false;
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}
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#endif
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#if CONFIG_PGTABLE_LEVELS > 3
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pud_t kasan_early_shadow_pud[MAX_PTRS_PER_PUD] __page_aligned_bss;
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static inline bool kasan_pud_table(p4d_t p4d)
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{
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return p4d_page(p4d) == virt_to_page(lm_alias(kasan_early_shadow_pud));
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}
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#else
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static inline bool kasan_pud_table(p4d_t p4d)
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{
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return false;
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}
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#endif
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#if CONFIG_PGTABLE_LEVELS > 2
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pmd_t kasan_early_shadow_pmd[MAX_PTRS_PER_PMD] __page_aligned_bss;
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static inline bool kasan_pmd_table(pud_t pud)
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{
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return pud_page(pud) == virt_to_page(lm_alias(kasan_early_shadow_pmd));
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}
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#else
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static inline bool kasan_pmd_table(pud_t pud)
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{
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return false;
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}
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#endif
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pte_t kasan_early_shadow_pte[MAX_PTRS_PER_PTE + PTE_HWTABLE_PTRS]
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__page_aligned_bss;
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static inline bool kasan_pte_table(pmd_t pmd)
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{
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return pmd_page(pmd) == virt_to_page(lm_alias(kasan_early_shadow_pte));
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}
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static inline bool kasan_early_shadow_page_entry(pte_t pte)
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{
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return pte_page(pte) == virt_to_page(lm_alias(kasan_early_shadow_page));
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}
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static __init void *early_alloc(size_t size, int node)
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{
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void *ptr = memblock_alloc_try_nid(size, size, __pa(MAX_DMA_ADDRESS),
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MEMBLOCK_ALLOC_ACCESSIBLE, node);
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if (!ptr)
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panic("%s: Failed to allocate %zu bytes align=%zx nid=%d from=%llx\n",
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__func__, size, size, node, (u64)__pa(MAX_DMA_ADDRESS));
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return ptr;
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}
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static void __ref zero_pte_populate(pmd_t *pmd, unsigned long addr,
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unsigned long end)
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{
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pte_t *pte = pte_offset_kernel(pmd, addr);
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pte_t zero_pte;
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zero_pte = pfn_pte(PFN_DOWN(__pa_symbol(kasan_early_shadow_page)),
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PAGE_KERNEL);
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zero_pte = pte_wrprotect(zero_pte);
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while (addr + PAGE_SIZE <= end) {
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set_pte_at(&init_mm, addr, pte, zero_pte);
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addr += PAGE_SIZE;
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pte = pte_offset_kernel(pmd, addr);
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}
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}
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static int __ref zero_pmd_populate(pud_t *pud, unsigned long addr,
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unsigned long end)
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{
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pmd_t *pmd = pmd_offset(pud, addr);
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unsigned long next;
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do {
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next = pmd_addr_end(addr, end);
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if (IS_ALIGNED(addr, PMD_SIZE) && end - addr >= PMD_SIZE) {
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pmd_populate_kernel(&init_mm, pmd,
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lm_alias(kasan_early_shadow_pte));
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continue;
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}
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if (pmd_none(*pmd)) {
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pte_t *p;
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if (slab_is_available())
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p = pte_alloc_one_kernel(&init_mm);
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else
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p = early_alloc(PAGE_SIZE, NUMA_NO_NODE);
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if (!p)
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return -ENOMEM;
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pmd_populate_kernel(&init_mm, pmd, p);
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}
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zero_pte_populate(pmd, addr, next);
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} while (pmd++, addr = next, addr != end);
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return 0;
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}
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static int __ref zero_pud_populate(p4d_t *p4d, unsigned long addr,
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unsigned long end)
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{
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pud_t *pud = pud_offset(p4d, addr);
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unsigned long next;
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do {
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next = pud_addr_end(addr, end);
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if (IS_ALIGNED(addr, PUD_SIZE) && end - addr >= PUD_SIZE) {
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pmd_t *pmd;
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pud_populate(&init_mm, pud,
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lm_alias(kasan_early_shadow_pmd));
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pmd = pmd_offset(pud, addr);
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pmd_populate_kernel(&init_mm, pmd,
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lm_alias(kasan_early_shadow_pte));
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continue;
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}
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if (pud_none(*pud)) {
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pmd_t *p;
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if (slab_is_available()) {
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p = pmd_alloc(&init_mm, pud, addr);
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if (!p)
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return -ENOMEM;
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} else {
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pud_populate(&init_mm, pud,
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early_alloc(PAGE_SIZE, NUMA_NO_NODE));
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}
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}
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zero_pmd_populate(pud, addr, next);
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} while (pud++, addr = next, addr != end);
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return 0;
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}
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static int __ref zero_p4d_populate(pgd_t *pgd, unsigned long addr,
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unsigned long end)
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{
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p4d_t *p4d = p4d_offset(pgd, addr);
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unsigned long next;
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do {
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next = p4d_addr_end(addr, end);
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if (IS_ALIGNED(addr, P4D_SIZE) && end - addr >= P4D_SIZE) {
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pud_t *pud;
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pmd_t *pmd;
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p4d_populate(&init_mm, p4d,
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lm_alias(kasan_early_shadow_pud));
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pud = pud_offset(p4d, addr);
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pud_populate(&init_mm, pud,
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lm_alias(kasan_early_shadow_pmd));
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pmd = pmd_offset(pud, addr);
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pmd_populate_kernel(&init_mm, pmd,
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lm_alias(kasan_early_shadow_pte));
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continue;
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}
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if (p4d_none(*p4d)) {
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pud_t *p;
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if (slab_is_available()) {
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p = pud_alloc(&init_mm, p4d, addr);
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if (!p)
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return -ENOMEM;
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} else {
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p4d_populate(&init_mm, p4d,
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early_alloc(PAGE_SIZE, NUMA_NO_NODE));
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}
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}
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zero_pud_populate(p4d, addr, next);
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} while (p4d++, addr = next, addr != end);
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return 0;
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}
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/**
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* kasan_populate_early_shadow - populate shadow memory region with
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* kasan_early_shadow_page
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* @shadow_start: start of the memory range to populate
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* @shadow_end: end of the memory range to populate
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*/
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int __ref kasan_populate_early_shadow(const void *shadow_start,
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const void *shadow_end)
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{
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unsigned long addr = (unsigned long)shadow_start;
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unsigned long end = (unsigned long)shadow_end;
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pgd_t *pgd = pgd_offset_k(addr);
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unsigned long next;
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do {
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next = pgd_addr_end(addr, end);
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if (IS_ALIGNED(addr, PGDIR_SIZE) && end - addr >= PGDIR_SIZE) {
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p4d_t *p4d;
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pud_t *pud;
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pmd_t *pmd;
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/*
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* kasan_early_shadow_pud should be populated with pmds
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* at this moment.
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* [pud,pmd]_populate*() below needed only for
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* 3,2 - level page tables where we don't have
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* puds,pmds, so pgd_populate(), pud_populate()
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* is noops.
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*/
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pgd_populate(&init_mm, pgd,
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lm_alias(kasan_early_shadow_p4d));
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p4d = p4d_offset(pgd, addr);
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p4d_populate(&init_mm, p4d,
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lm_alias(kasan_early_shadow_pud));
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pud = pud_offset(p4d, addr);
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pud_populate(&init_mm, pud,
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lm_alias(kasan_early_shadow_pmd));
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pmd = pmd_offset(pud, addr);
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pmd_populate_kernel(&init_mm, pmd,
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lm_alias(kasan_early_shadow_pte));
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continue;
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}
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if (pgd_none(*pgd)) {
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p4d_t *p;
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if (slab_is_available()) {
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p = p4d_alloc(&init_mm, pgd, addr);
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if (!p)
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return -ENOMEM;
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} else {
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pgd_populate(&init_mm, pgd,
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early_alloc(PAGE_SIZE, NUMA_NO_NODE));
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}
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}
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zero_p4d_populate(pgd, addr, next);
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} while (pgd++, addr = next, addr != end);
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return 0;
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}
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static void kasan_free_pte(pte_t *pte_start, pmd_t *pmd)
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{
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pte_t *pte;
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int i;
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for (i = 0; i < PTRS_PER_PTE; i++) {
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pte = pte_start + i;
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if (!pte_none(*pte))
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return;
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}
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pte_free_kernel(&init_mm, (pte_t *)page_to_virt(pmd_page(*pmd)));
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pmd_clear(pmd);
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}
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static void kasan_free_pmd(pmd_t *pmd_start, pud_t *pud)
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{
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pmd_t *pmd;
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int i;
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for (i = 0; i < PTRS_PER_PMD; i++) {
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pmd = pmd_start + i;
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if (!pmd_none(*pmd))
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return;
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}
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pmd_free(&init_mm, (pmd_t *)page_to_virt(pud_page(*pud)));
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pud_clear(pud);
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}
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static void kasan_free_pud(pud_t *pud_start, p4d_t *p4d)
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{
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pud_t *pud;
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int i;
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for (i = 0; i < PTRS_PER_PUD; i++) {
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pud = pud_start + i;
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if (!pud_none(*pud))
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return;
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}
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pud_free(&init_mm, (pud_t *)page_to_virt(p4d_page(*p4d)));
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p4d_clear(p4d);
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}
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static void kasan_free_p4d(p4d_t *p4d_start, pgd_t *pgd)
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{
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p4d_t *p4d;
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int i;
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for (i = 0; i < PTRS_PER_P4D; i++) {
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p4d = p4d_start + i;
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if (!p4d_none(*p4d))
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return;
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}
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p4d_free(&init_mm, (p4d_t *)page_to_virt(pgd_page(*pgd)));
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pgd_clear(pgd);
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}
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static void kasan_remove_pte_table(pte_t *pte, unsigned long addr,
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unsigned long end)
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{
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unsigned long next;
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for (; addr < end; addr = next, pte++) {
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next = (addr + PAGE_SIZE) & PAGE_MASK;
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if (next > end)
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next = end;
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if (!pte_present(*pte))
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continue;
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if (WARN_ON(!kasan_early_shadow_page_entry(*pte)))
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continue;
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pte_clear(&init_mm, addr, pte);
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}
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}
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static void kasan_remove_pmd_table(pmd_t *pmd, unsigned long addr,
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unsigned long end)
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{
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unsigned long next;
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for (; addr < end; addr = next, pmd++) {
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pte_t *pte;
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next = pmd_addr_end(addr, end);
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if (!pmd_present(*pmd))
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continue;
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if (kasan_pte_table(*pmd)) {
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if (IS_ALIGNED(addr, PMD_SIZE) &&
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IS_ALIGNED(next, PMD_SIZE)) {
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pmd_clear(pmd);
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continue;
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}
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}
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pte = pte_offset_kernel(pmd, addr);
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kasan_remove_pte_table(pte, addr, next);
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kasan_free_pte(pte_offset_kernel(pmd, 0), pmd);
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}
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}
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static void kasan_remove_pud_table(pud_t *pud, unsigned long addr,
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unsigned long end)
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{
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unsigned long next;
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for (; addr < end; addr = next, pud++) {
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pmd_t *pmd, *pmd_base;
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next = pud_addr_end(addr, end);
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if (!pud_present(*pud))
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continue;
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if (kasan_pmd_table(*pud)) {
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if (IS_ALIGNED(addr, PUD_SIZE) &&
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IS_ALIGNED(next, PUD_SIZE)) {
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pud_clear(pud);
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continue;
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}
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}
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pmd = pmd_offset(pud, addr);
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pmd_base = pmd_offset(pud, 0);
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kasan_remove_pmd_table(pmd, addr, next);
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kasan_free_pmd(pmd_base, pud);
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}
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}
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static void kasan_remove_p4d_table(p4d_t *p4d, unsigned long addr,
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unsigned long end)
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{
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unsigned long next;
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for (; addr < end; addr = next, p4d++) {
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pud_t *pud;
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next = p4d_addr_end(addr, end);
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if (!p4d_present(*p4d))
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continue;
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if (kasan_pud_table(*p4d)) {
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if (IS_ALIGNED(addr, P4D_SIZE) &&
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IS_ALIGNED(next, P4D_SIZE)) {
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p4d_clear(p4d);
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continue;
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}
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}
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pud = pud_offset(p4d, addr);
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kasan_remove_pud_table(pud, addr, next);
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kasan_free_pud(pud_offset(p4d, 0), p4d);
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}
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}
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void kasan_remove_zero_shadow(void *start, unsigned long size)
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{
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unsigned long addr, end, next;
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pgd_t *pgd;
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addr = (unsigned long)kasan_mem_to_shadow(start);
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end = addr + (size >> KASAN_SHADOW_SCALE_SHIFT);
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if (WARN_ON((unsigned long)start % KASAN_MEMORY_PER_SHADOW_PAGE) ||
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WARN_ON(size % KASAN_MEMORY_PER_SHADOW_PAGE))
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return;
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for (; addr < end; addr = next) {
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p4d_t *p4d;
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next = pgd_addr_end(addr, end);
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pgd = pgd_offset_k(addr);
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if (!pgd_present(*pgd))
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continue;
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if (kasan_p4d_table(*pgd)) {
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if (IS_ALIGNED(addr, PGDIR_SIZE) &&
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IS_ALIGNED(next, PGDIR_SIZE)) {
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pgd_clear(pgd);
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continue;
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}
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}
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p4d = p4d_offset(pgd, addr);
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kasan_remove_p4d_table(p4d, addr, next);
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kasan_free_p4d(p4d_offset(pgd, 0), pgd);
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}
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}
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int kasan_add_zero_shadow(void *start, unsigned long size)
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{
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int ret;
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void *shadow_start, *shadow_end;
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shadow_start = kasan_mem_to_shadow(start);
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shadow_end = shadow_start + (size >> KASAN_SHADOW_SCALE_SHIFT);
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if (WARN_ON((unsigned long)start % KASAN_MEMORY_PER_SHADOW_PAGE) ||
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WARN_ON(size % KASAN_MEMORY_PER_SHADOW_PAGE))
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return -EINVAL;
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ret = kasan_populate_early_shadow(shadow_start, shadow_end);
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if (ret)
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kasan_remove_zero_shadow(start, size);
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return ret;
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}
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