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Merge branch 'mm-kasan-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Browse source 
Pull x86/kasan changes from Ingo Molnar:
 "These are two KASAN changes that factor out (and generalize) x86
  specific KASAN code from x86 to mm"

* 'mm-kasan-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/kasan, mm: Introduce generic kasan_populate_zero_shadow()
  x86/kasan: Define KASAN_SHADOW_OFFSET per architecture
This commit is contained in:
Linus Torvalds 2015-08-31 19:16:36 -07:00
commit 4658000955
5 changed files with 170 additions and 120 deletions
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3
arch/x86/include/asm/kasan.h
View file

@ -1,6 +1,9 @@
#ifndef _ASM_X86_KASAN_H
#define _ASM_X86_KASAN_H
#include <linux/const.h>
#define KASAN_SHADOW_OFFSET _AC(CONFIG_KASAN_SHADOW_OFFSET, UL)
/*
* Compiler uses shadow offset assuming that addresses start
* from 0. Kernel addresses don't start from 0, so shadow

123
arch/x86/mm/kasan_init_64.c
View file

@ -12,20 +12,6 @@
extern pgd_t early_level4_pgt[PTRS_PER_PGD];
extern struct range pfn_mapped[E820_X_MAX];
static pud_t kasan_zero_pud[PTRS_PER_PUD] __page_aligned_bss;
static pmd_t kasan_zero_pmd[PTRS_PER_PMD] __page_aligned_bss;
static pte_t kasan_zero_pte[PTRS_PER_PTE] __page_aligned_bss;
/*
* This page used as early shadow. We don't use empty_zero_page
* at early stages, stack instrumentation could write some garbage
* to this page.
* Latter we reuse it as zero shadow for large ranges of memory
* that allowed to access, but not instrumented by kasan
* (vmalloc/vmemmap ...).
*/
static unsigned char kasan_zero_page[PAGE_SIZE] __page_aligned_bss;
static int __init map_range(struct range *range)
{
unsigned long start;
@ -62,106 +48,6 @@ static void __init kasan_map_early_shadow(pgd_t *pgd)
}
}
static int __init zero_pte_populate(pmd_t *pmd, unsigned long addr,
unsigned long end)
{
pte_t *pte = pte_offset_kernel(pmd, addr);
while (addr + PAGE_SIZE <= end) {
WARN_ON(!pte_none(*pte));
set_pte(pte, __pte(__pa_nodebug(kasan_zero_page)
| __PAGE_KERNEL_RO));
addr += PAGE_SIZE;
pte = pte_offset_kernel(pmd, addr);
}
return 0;
}
static int __init zero_pmd_populate(pud_t *pud, unsigned long addr,
unsigned long end)
{
int ret = 0;
pmd_t *pmd = pmd_offset(pud, addr);
while (IS_ALIGNED(addr, PMD_SIZE) && addr + PMD_SIZE <= end) {
WARN_ON(!pmd_none(*pmd));
set_pmd(pmd, __pmd(__pa_nodebug(kasan_zero_pte)
| _KERNPG_TABLE));
addr += PMD_SIZE;
pmd = pmd_offset(pud, addr);
}
if (addr < end) {
if (pmd_none(*pmd)) {
void *p = vmemmap_alloc_block(PAGE_SIZE, NUMA_NO_NODE);
if (!p)
return -ENOMEM;
set_pmd(pmd, __pmd(__pa_nodebug(p) | _KERNPG_TABLE));
}
ret = zero_pte_populate(pmd, addr, end);
}
return ret;
}
static int __init zero_pud_populate(pgd_t *pgd, unsigned long addr,
unsigned long end)
{
int ret = 0;
pud_t *pud = pud_offset(pgd, addr);
while (IS_ALIGNED(addr, PUD_SIZE) && addr + PUD_SIZE <= end) {
WARN_ON(!pud_none(*pud));
set_pud(pud, __pud(__pa_nodebug(kasan_zero_pmd)
| _KERNPG_TABLE));
addr += PUD_SIZE;
pud = pud_offset(pgd, addr);
}
if (addr < end) {
if (pud_none(*pud)) {
void *p = vmemmap_alloc_block(PAGE_SIZE, NUMA_NO_NODE);
if (!p)
return -ENOMEM;
set_pud(pud, __pud(__pa_nodebug(p) | _KERNPG_TABLE));
}
ret = zero_pmd_populate(pud, addr, end);
}
return ret;
}
static int __init zero_pgd_populate(unsigned long addr, unsigned long end)
{
int ret = 0;
pgd_t *pgd = pgd_offset_k(addr);
while (IS_ALIGNED(addr, PGDIR_SIZE) && addr + PGDIR_SIZE <= end) {
WARN_ON(!pgd_none(*pgd));
set_pgd(pgd, __pgd(__pa_nodebug(kasan_zero_pud)
| _KERNPG_TABLE));
addr += PGDIR_SIZE;
pgd = pgd_offset_k(addr);
}
if (addr < end) {
if (pgd_none(*pgd)) {
void *p = vmemmap_alloc_block(PAGE_SIZE, NUMA_NO_NODE);
if (!p)
return -ENOMEM;
set_pgd(pgd, __pgd(__pa_nodebug(p) | _KERNPG_TABLE));
}
ret = zero_pud_populate(pgd, addr, end);
}
return ret;
}
static void __init populate_zero_shadow(const void *start, const void *end)
{
if (zero_pgd_populate((unsigned long)start, (unsigned long)end))
panic("kasan: unable to map zero shadow!");
}
#ifdef CONFIG_KASAN_INLINE
static int kasan_die_handler(struct notifier_block *self,
unsigned long val,
@ -213,7 +99,7 @@ void __init kasan_init(void)
clear_pgds(KASAN_SHADOW_START, KASAN_SHADOW_END);
populate_zero_shadow((void *)KASAN_SHADOW_START,
kasan_populate_zero_shadow((void *)KASAN_SHADOW_START,
kasan_mem_to_shadow((void *)PAGE_OFFSET));
for (i = 0; i < E820_X_MAX; i++) {
@ -223,14 +109,15 @@ void __init kasan_init(void)
if (map_range(&pfn_mapped[i]))
panic("kasan: unable to allocate shadow!");
}
populate_zero_shadow(kasan_mem_to_shadow((void *)PAGE_OFFSET + MAXMEM),
kasan_mem_to_shadow((void *)__START_KERNEL_map));
kasan_populate_zero_shadow(
kasan_mem_to_shadow((void *)PAGE_OFFSET + MAXMEM),
kasan_mem_to_shadow((void *)__START_KERNEL_map));
vmemmap_populate((unsigned long)kasan_mem_to_shadow(_stext),
(unsigned long)kasan_mem_to_shadow(_end),
NUMA_NO_NODE);
populate_zero_shadow(kasan_mem_to_shadow((void *)MODULES_END),
kasan_populate_zero_shadow(kasan_mem_to_shadow((void *)MODULES_END),
(void *)KASAN_SHADOW_END);
memset(kasan_zero_page, 0, PAGE_SIZE);

10
include/linux/kasan.h
View file

@ -10,11 +10,19 @@ struct vm_struct;
#ifdef CONFIG_KASAN
#define KASAN_SHADOW_SCALE_SHIFT 3
#define KASAN_SHADOW_OFFSET _AC(CONFIG_KASAN_SHADOW_OFFSET, UL)
#include <asm/kasan.h>
#include <asm/pgtable.h>
#include <linux/sched.h>
extern unsigned char kasan_zero_page[PAGE_SIZE];
extern pte_t kasan_zero_pte[PTRS_PER_PTE];
extern pmd_t kasan_zero_pmd[PTRS_PER_PMD];
extern pud_t kasan_zero_pud[PTRS_PER_PUD];
void kasan_populate_zero_shadow(const void *shadow_start,
const void *shadow_end);
static inline void *kasan_mem_to_shadow(const void *addr)
{
return (void *)((unsigned long)addr >> KASAN_SHADOW_SCALE_SHIFT)

2
mm/kasan/Makefile
View file

@ -5,4 +5,4 @@ CFLAGS_REMOVE_kasan.o = -pg
# see: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63533
CFLAGS_kasan.o := $(call cc-option, -fno-conserve-stack -fno-stack-protector)
obj-y := kasan.o report.o
obj-y := kasan.o report.o kasan_init.o

152
mm/kasan/kasan_init.c Normal file
View file

@ -0,0 +1,152 @@
/*
* 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/pfn.h>
#include <asm/page.h>
#include <asm/pgalloc.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 > 3
pud_t kasan_zero_pud[PTRS_PER_PUD] __page_aligned_bss;
#endif
#if CONFIG_PGTABLE_LEVELS > 2
pmd_t kasan_zero_pmd[PTRS_PER_PMD] __page_aligned_bss;
#endif
pte_t kasan_zero_pte[PTRS_PER_PTE] __page_aligned_bss;
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 __init 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(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 void __init 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, kasan_zero_pte);
continue;
}
if (pmd_none(*pmd)) {
pmd_populate_kernel(&init_mm, pmd,
early_alloc(PAGE_SIZE, NUMA_NO_NODE));
}
zero_pte_populate(pmd, addr, next);
} while (pmd++, addr = next, addr != end);
}
static void __init zero_pud_populate(pgd_t *pgd, unsigned long addr,
unsigned long end)
{
pud_t *pud = pud_offset(pgd, 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, kasan_zero_pmd);
pmd = pmd_offset(pud, addr);
pmd_populate_kernel(&init_mm, pmd, kasan_zero_pte);
continue;
}
if (pud_none(*pud)) {
pud_populate(&init_mm, pud,
early_alloc(PAGE_SIZE, NUMA_NO_NODE));
}
zero_pmd_populate(pud, addr, next);
} while (pud++, addr = next, addr != end);
}
/**
* 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
*/
void __init 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) {
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.
*/
pgd_populate(&init_mm, pgd, kasan_zero_pud);
pud = pud_offset(pgd, addr);
pud_populate(&init_mm, pud, kasan_zero_pmd);
pmd = pmd_offset(pud, addr);
pmd_populate_kernel(&init_mm, pmd, kasan_zero_pte);
continue;
}
if (pgd_none(*pgd)) {
pgd_populate(&init_mm, pgd,
early_alloc(PAGE_SIZE, NUMA_NO_NODE));
}
zero_pud_populate(pgd, addr, next);
} while (pgd++, addr = next, addr != end);
}