linux/arch/s390/mm/kasan_init.c
Vasily Gorbik 3e39ce266a s390/kasan: add KASAN_VMALLOC support
Add KASAN_VMALLOC support which now enables vmalloc memory area access
checks as well as enables usage of VMAP_STACK under kasan.

KASAN_VMALLOC changes the way vmalloc and modules areas shadow memory
is handled. With this new approach only top level page tables are
pre-populated and lower levels are filled dynamically upon memory
allocation.

Acked-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
2019-12-11 19:56:59 +01:00

427 lines
12 KiB
C

// SPDX-License-Identifier: GPL-2.0
#include <linux/kasan.h>
#include <linux/sched/task.h>
#include <linux/memblock.h>
#include <asm/pgalloc.h>
#include <asm/pgtable.h>
#include <asm/kasan.h>
#include <asm/mem_detect.h>
#include <asm/processor.h>
#include <asm/sclp.h>
#include <asm/facility.h>
#include <asm/sections.h>
#include <asm/setup.h>
static unsigned long segment_pos __initdata;
static unsigned long segment_low __initdata;
static unsigned long pgalloc_pos __initdata;
static unsigned long pgalloc_low __initdata;
static unsigned long pgalloc_freeable __initdata;
static bool has_edat __initdata;
static bool has_nx __initdata;
#define __sha(x) ((unsigned long)kasan_mem_to_shadow((void *)x))
static pgd_t early_pg_dir[PTRS_PER_PGD] __initdata __aligned(PAGE_SIZE);
static void __init kasan_early_panic(const char *reason)
{
sclp_early_printk("The Linux kernel failed to boot with the KernelAddressSanitizer:\n");
sclp_early_printk(reason);
disabled_wait();
}
static void * __init kasan_early_alloc_segment(void)
{
segment_pos -= _SEGMENT_SIZE;
if (segment_pos < segment_low)
kasan_early_panic("out of memory during initialisation\n");
return (void *)segment_pos;
}
static void * __init kasan_early_alloc_pages(unsigned int order)
{
pgalloc_pos -= (PAGE_SIZE << order);
if (pgalloc_pos < pgalloc_low)
kasan_early_panic("out of memory during initialisation\n");
return (void *)pgalloc_pos;
}
static void * __init kasan_early_crst_alloc(unsigned long val)
{
unsigned long *table;
table = kasan_early_alloc_pages(CRST_ALLOC_ORDER);
if (table)
crst_table_init(table, val);
return table;
}
static pte_t * __init kasan_early_pte_alloc(void)
{
static void *pte_leftover;
pte_t *pte;
BUILD_BUG_ON(_PAGE_TABLE_SIZE * 2 != PAGE_SIZE);
if (!pte_leftover) {
pte_leftover = kasan_early_alloc_pages(0);
pte = pte_leftover + _PAGE_TABLE_SIZE;
} else {
pte = pte_leftover;
pte_leftover = NULL;
}
memset64((u64 *)pte, _PAGE_INVALID, PTRS_PER_PTE);
return pte;
}
enum populate_mode {
POPULATE_ONE2ONE,
POPULATE_MAP,
POPULATE_ZERO_SHADOW,
POPULATE_SHALLOW
};
static void __init kasan_early_vmemmap_populate(unsigned long address,
unsigned long end,
enum populate_mode mode)
{
unsigned long pgt_prot_zero, pgt_prot, sgt_prot;
pgd_t *pg_dir;
p4d_t *p4_dir;
pud_t *pu_dir;
pmd_t *pm_dir;
pte_t *pt_dir;
pgt_prot_zero = pgprot_val(PAGE_KERNEL_RO);
if (!has_nx)
pgt_prot_zero &= ~_PAGE_NOEXEC;
pgt_prot = pgprot_val(PAGE_KERNEL_EXEC);
sgt_prot = pgprot_val(SEGMENT_KERNEL_EXEC);
while (address < end) {
pg_dir = pgd_offset_k(address);
if (pgd_none(*pg_dir)) {
if (mode == POPULATE_ZERO_SHADOW &&
IS_ALIGNED(address, PGDIR_SIZE) &&
end - address >= PGDIR_SIZE) {
pgd_populate(&init_mm, pg_dir,
kasan_early_shadow_p4d);
address = (address + PGDIR_SIZE) & PGDIR_MASK;
continue;
}
p4_dir = kasan_early_crst_alloc(_REGION2_ENTRY_EMPTY);
pgd_populate(&init_mm, pg_dir, p4_dir);
}
if (IS_ENABLED(CONFIG_KASAN_S390_4_LEVEL_PAGING) &&
mode == POPULATE_SHALLOW) {
address = (address + P4D_SIZE) & P4D_MASK;
continue;
}
p4_dir = p4d_offset(pg_dir, address);
if (p4d_none(*p4_dir)) {
if (mode == POPULATE_ZERO_SHADOW &&
IS_ALIGNED(address, P4D_SIZE) &&
end - address >= P4D_SIZE) {
p4d_populate(&init_mm, p4_dir,
kasan_early_shadow_pud);
address = (address + P4D_SIZE) & P4D_MASK;
continue;
}
pu_dir = kasan_early_crst_alloc(_REGION3_ENTRY_EMPTY);
p4d_populate(&init_mm, p4_dir, pu_dir);
}
if (!IS_ENABLED(CONFIG_KASAN_S390_4_LEVEL_PAGING) &&
mode == POPULATE_SHALLOW) {
address = (address + PUD_SIZE) & PUD_MASK;
continue;
}
pu_dir = pud_offset(p4_dir, address);
if (pud_none(*pu_dir)) {
if (mode == POPULATE_ZERO_SHADOW &&
IS_ALIGNED(address, PUD_SIZE) &&
end - address >= PUD_SIZE) {
pud_populate(&init_mm, pu_dir,
kasan_early_shadow_pmd);
address = (address + PUD_SIZE) & PUD_MASK;
continue;
}
pm_dir = kasan_early_crst_alloc(_SEGMENT_ENTRY_EMPTY);
pud_populate(&init_mm, pu_dir, pm_dir);
}
pm_dir = pmd_offset(pu_dir, address);
if (pmd_none(*pm_dir)) {
if (mode == POPULATE_ZERO_SHADOW &&
IS_ALIGNED(address, PMD_SIZE) &&
end - address >= PMD_SIZE) {
pmd_populate(&init_mm, pm_dir,
kasan_early_shadow_pte);
address = (address + PMD_SIZE) & PMD_MASK;
continue;
}
/* the first megabyte of 1:1 is mapped with 4k pages */
if (has_edat && address && end - address >= PMD_SIZE &&
mode != POPULATE_ZERO_SHADOW) {
void *page;
if (mode == POPULATE_ONE2ONE) {
page = (void *)address;
} else {
page = kasan_early_alloc_segment();
memset(page, 0, _SEGMENT_SIZE);
}
pmd_val(*pm_dir) = __pa(page) | sgt_prot;
address = (address + PMD_SIZE) & PMD_MASK;
continue;
}
pt_dir = kasan_early_pte_alloc();
pmd_populate(&init_mm, pm_dir, pt_dir);
} else if (pmd_large(*pm_dir)) {
address = (address + PMD_SIZE) & PMD_MASK;
continue;
}
pt_dir = pte_offset_kernel(pm_dir, address);
if (pte_none(*pt_dir)) {
void *page;
switch (mode) {
case POPULATE_ONE2ONE:
page = (void *)address;
pte_val(*pt_dir) = __pa(page) | pgt_prot;
break;
case POPULATE_MAP:
page = kasan_early_alloc_pages(0);
memset(page, 0, PAGE_SIZE);
pte_val(*pt_dir) = __pa(page) | pgt_prot;
break;
case POPULATE_ZERO_SHADOW:
page = kasan_early_shadow_page;
pte_val(*pt_dir) = __pa(page) | pgt_prot_zero;
break;
case POPULATE_SHALLOW:
/* should never happen */
break;
}
}
address += PAGE_SIZE;
}
}
static void __init kasan_set_pgd(pgd_t *pgd, unsigned long asce_type)
{
unsigned long asce_bits;
asce_bits = asce_type | _ASCE_TABLE_LENGTH;
S390_lowcore.kernel_asce = (__pa(pgd) & PAGE_MASK) | asce_bits;
S390_lowcore.user_asce = S390_lowcore.kernel_asce;
__ctl_load(S390_lowcore.kernel_asce, 1, 1);
__ctl_load(S390_lowcore.kernel_asce, 7, 7);
__ctl_load(S390_lowcore.kernel_asce, 13, 13);
}
static void __init kasan_enable_dat(void)
{
psw_t psw;
psw.mask = __extract_psw();
psw_bits(psw).dat = 1;
psw_bits(psw).as = PSW_BITS_AS_HOME;
__load_psw_mask(psw.mask);
}
static void __init kasan_early_detect_facilities(void)
{
if (test_facility(8)) {
has_edat = true;
__ctl_set_bit(0, 23);
}
if (!noexec_disabled && test_facility(130)) {
has_nx = true;
__ctl_set_bit(0, 20);
}
}
void __init kasan_early_init(void)
{
unsigned long untracked_mem_end;
unsigned long shadow_alloc_size;
unsigned long initrd_end;
unsigned long asce_type;
unsigned long memsize;
unsigned long vmax;
unsigned long pgt_prot = pgprot_val(PAGE_KERNEL_RO);
pte_t pte_z;
pmd_t pmd_z = __pmd(__pa(kasan_early_shadow_pte) | _SEGMENT_ENTRY);
pud_t pud_z = __pud(__pa(kasan_early_shadow_pmd) | _REGION3_ENTRY);
p4d_t p4d_z = __p4d(__pa(kasan_early_shadow_pud) | _REGION2_ENTRY);
kasan_early_detect_facilities();
if (!has_nx)
pgt_prot &= ~_PAGE_NOEXEC;
pte_z = __pte(__pa(kasan_early_shadow_page) | pgt_prot);
memsize = get_mem_detect_end();
if (!memsize)
kasan_early_panic("cannot detect physical memory size\n");
/* respect mem= cmdline parameter */
if (memory_end_set && memsize > memory_end)
memsize = memory_end;
if (IS_ENABLED(CONFIG_CRASH_DUMP) && OLDMEM_BASE)
memsize = min(memsize, OLDMEM_SIZE);
memsize = min(memsize, KASAN_SHADOW_START);
if (IS_ENABLED(CONFIG_KASAN_S390_4_LEVEL_PAGING)) {
/* 4 level paging */
BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_START, P4D_SIZE));
BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, P4D_SIZE));
crst_table_init((unsigned long *)early_pg_dir,
_REGION2_ENTRY_EMPTY);
untracked_mem_end = vmax = _REGION1_SIZE;
asce_type = _ASCE_TYPE_REGION2;
} else {
/* 3 level paging */
BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_START, PUD_SIZE));
BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, PUD_SIZE));
crst_table_init((unsigned long *)early_pg_dir,
_REGION3_ENTRY_EMPTY);
untracked_mem_end = vmax = _REGION2_SIZE;
asce_type = _ASCE_TYPE_REGION3;
}
/* init kasan zero shadow */
crst_table_init((unsigned long *)kasan_early_shadow_p4d,
p4d_val(p4d_z));
crst_table_init((unsigned long *)kasan_early_shadow_pud,
pud_val(pud_z));
crst_table_init((unsigned long *)kasan_early_shadow_pmd,
pmd_val(pmd_z));
memset64((u64 *)kasan_early_shadow_pte, pte_val(pte_z), PTRS_PER_PTE);
shadow_alloc_size = memsize >> KASAN_SHADOW_SCALE_SHIFT;
pgalloc_low = round_up((unsigned long)_end, _SEGMENT_SIZE);
if (IS_ENABLED(CONFIG_BLK_DEV_INITRD)) {
initrd_end =
round_up(INITRD_START + INITRD_SIZE, _SEGMENT_SIZE);
pgalloc_low = max(pgalloc_low, initrd_end);
}
if (pgalloc_low + shadow_alloc_size > memsize)
kasan_early_panic("out of memory during initialisation\n");
if (has_edat) {
segment_pos = round_down(memsize, _SEGMENT_SIZE);
segment_low = segment_pos - shadow_alloc_size;
pgalloc_pos = segment_low;
} else {
pgalloc_pos = memsize;
}
init_mm.pgd = early_pg_dir;
/*
* Current memory layout:
* +- 0 -------------+ +- shadow start -+
* | 1:1 ram mapping | /| 1/8 ram |
* | | / | |
* +- end of ram ----+ / +----------------+
* | ... gap ... | / | |
* | |/ | kasan |
* +- shadow start --+ | zero |
* | 1/8 addr space | | page |
* +- shadow end -+ | mapping |
* | ... gap ... |\ | (untracked) |
* +- vmalloc area -+ \ | |
* | vmalloc_size | \ | |
* +- modules vaddr -+ \ +----------------+
* | 2Gb | \| unmapped | allocated per module
* +-----------------+ +- shadow end ---+
*
* Current memory layout (KASAN_VMALLOC):
* +- 0 -------------+ +- shadow start -+
* | 1:1 ram mapping | /| 1/8 ram |
* | | / | |
* +- end of ram ----+ / +----------------+
* | ... gap ... | / | kasan |
* | |/ | zero |
* +- shadow start --+ | page |
* | 1/8 addr space | | mapping |
* +- shadow end -+ | (untracked) |
* | ... gap ... |\ | |
* +- vmalloc area -+ \ +- vmalloc area -+
* | vmalloc_size | \ |shallow populate|
* +- modules vaddr -+ \ +- modules area -+
* | 2Gb | \|shallow populate|
* +-----------------+ +- shadow end ---+
*/
/* populate kasan shadow (for identity mapping and zero page mapping) */
kasan_early_vmemmap_populate(__sha(0), __sha(memsize), POPULATE_MAP);
if (IS_ENABLED(CONFIG_MODULES))
untracked_mem_end = vmax - MODULES_LEN;
if (IS_ENABLED(CONFIG_KASAN_VMALLOC)) {
untracked_mem_end = vmax - vmalloc_size - MODULES_LEN;
/* shallowly populate kasan shadow for vmalloc and modules */
kasan_early_vmemmap_populate(__sha(untracked_mem_end),
__sha(vmax), POPULATE_SHALLOW);
}
/* populate kasan shadow for untracked memory */
kasan_early_vmemmap_populate(__sha(max_physmem_end),
__sha(untracked_mem_end),
POPULATE_ZERO_SHADOW);
/* memory allocated for identity mapping structs will be freed later */
pgalloc_freeable = pgalloc_pos;
/* populate identity mapping */
kasan_early_vmemmap_populate(0, memsize, POPULATE_ONE2ONE);
kasan_set_pgd(early_pg_dir, asce_type);
kasan_enable_dat();
/* enable kasan */
init_task.kasan_depth = 0;
memblock_reserve(pgalloc_pos, memsize - pgalloc_pos);
sclp_early_printk("KernelAddressSanitizer initialized\n");
}
void __init kasan_copy_shadow(pgd_t *pg_dir)
{
/*
* At this point we are still running on early pages setup early_pg_dir,
* while swapper_pg_dir has just been initialized with identity mapping.
* Carry over shadow memory region from early_pg_dir to swapper_pg_dir.
*/
pgd_t *pg_dir_src;
pgd_t *pg_dir_dst;
p4d_t *p4_dir_src;
p4d_t *p4_dir_dst;
pud_t *pu_dir_src;
pud_t *pu_dir_dst;
pg_dir_src = pgd_offset_raw(early_pg_dir, KASAN_SHADOW_START);
pg_dir_dst = pgd_offset_raw(pg_dir, KASAN_SHADOW_START);
p4_dir_src = p4d_offset(pg_dir_src, KASAN_SHADOW_START);
p4_dir_dst = p4d_offset(pg_dir_dst, KASAN_SHADOW_START);
if (!p4d_folded(*p4_dir_src)) {
/* 4 level paging */
memcpy(p4_dir_dst, p4_dir_src,
(KASAN_SHADOW_SIZE >> P4D_SHIFT) * sizeof(p4d_t));
return;
}
/* 3 level paging */
pu_dir_src = pud_offset(p4_dir_src, KASAN_SHADOW_START);
pu_dir_dst = pud_offset(p4_dir_dst, KASAN_SHADOW_START);
memcpy(pu_dir_dst, pu_dir_src,
(KASAN_SHADOW_SIZE >> PUD_SHIFT) * sizeof(pud_t));
}
void __init kasan_free_early_identity(void)
{
memblock_free(pgalloc_pos, pgalloc_freeable - pgalloc_pos);
}