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kmsan_instr.c
664 lines (583 loc) · 17.1 KB
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kmsan_instr.c
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/*
* KMSAN compiler API.
*
* Copyright (C) 2017 Google, Inc
* Author: Alexander Potapenko <glider@google.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 "kmsan.h"
#include <linux/gfp.h>
#include <linux/mm.h>
// TODO(glider): dummy shadow should be per-task.
// TODO(glider): ideally, there should be no dummy shadow once we're initialized.
// I.e. we need to remove IN_RUNTIME checks from the fast path.
void check_param_origin_tls(void)
{
kmsan_context_state *cstate = task_kmsan_context_state();
int i;
unsigned long flags;
return;
if (!kmsan_ready)
return;
for (i = 0; i < KMSAN_PARAM_SIZE / sizeof(depot_stack_handle_t); i++) {
if (cstate->param_origin_tls[i]) {
spin_lock_irqsave(&report_lock, flags);
dump_stack();
spin_unlock_irqrestore(&report_lock, flags);
}
cstate->param_origin_tls[i] = 0;
}
for (i = 0; i < KMSAN_PARAM_SIZE; i++) {
cstate->param_tls[i] = 0;
}
}
void check_vararg_meta(void)
{
kmsan_context_state *cstate = task_kmsan_context_state();
int i;
unsigned long irq_flags, flags;
if (!kmsan_ready)
return;
if (IN_RUNTIME() || !current->kmsan.enabled)
return;
ENTER_RUNTIME(irq_flags);
for (i = 0; i < KMSAN_PARAM_SIZE; i++) {
if (cstate->va_arg_tls[i]) {
spin_lock_irqsave(&report_lock, flags);
dump_stack();
spin_unlock_irqrestore(&report_lock, flags);
break;
}
}
LEAVE_RUNTIME(irq_flags);
}
// TODO(glider): remove this fn?
// Looks like it's enough to mark syscall entries non-instrumented.
void kmsan_wipe_params_shadow_origin()
{
int ind, num;
unsigned long irq_flags;
kmsan_context_state *cstate = task_kmsan_context_state();
if (!kmsan_ready)
return;
if (IN_RUNTIME() || !current->kmsan.enabled)
return;
ENTER_RUNTIME(irq_flags);
__memset(cstate->param_origin_tls, 0, KMSAN_PARAM_SIZE);
__memset(cstate->param_tls, 0, KMSAN_PARAM_SIZE);
__memset(cstate->va_arg_tls, 0, KMSAN_PARAM_SIZE);
__memset(cstate->va_arg_origin_tls, 0, KMSAN_PARAM_SIZE);
__memset(cstate->retval_tls, 0, RETVAL_SIZE);
cstate->retval_origin_tls = 0;
cstate->origin_tls = 0;
cstate->va_arg_overflow_size_tls = 0;
LEAVE_RUNTIME(irq_flags);
}
EXPORT_SYMBOL(kmsan_wipe_params_shadow_origin);
typedef struct {
void* s;
void* o;
} shadow_origin_ptr_t;
// Taken from arch/x86/mm/physaddr.h
// TODO(glider): do we need it?
static inline int my_phys_addr_valid(resource_size_t addr)
{
#ifdef CONFIG_PHYS_ADDR_T_64BIT
return !(addr >> boot_cpu_data.x86_phys_bits);
#else
return 1;
#endif
}
// Taken from arch/x86/mm/physaddr.c
// TODO(glider): do we need it?
static bool my_virt_addr_valid(unsigned long x)
{
unsigned long y = x - __START_KERNEL_map;
/* use the carry flag to determine if x was < __START_KERNEL_map */
if (unlikely(x > y)) {
x = y + phys_base;
if (y >= KERNEL_IMAGE_SIZE)
return false;
} else {
x = y + (__START_KERNEL_map - PAGE_OFFSET);
/* carry flag will be set if starting x was >= PAGE_OFFSET */
if ((x > y) || !my_phys_addr_valid(x))
return false;
}
return pfn_valid(x >> PAGE_SHIFT);
}
// TODO(glider): do we want to inline this into kmsan_instr.c?
// TODO(glider): either delete kmsan_get_shadow_address() or refactor.
/* kmsan_get_shadow_address_noruntime() must not be called from within runtime. */
inline
void *kmsan_get_shadow_address_inline(u64 addr, size_t size, bool checked)
{
struct page *page, *next_page;
unsigned long offset, shadow_size;
void *ret;
depot_stack_handle_t origin;
unsigned long irq_flags;
// TODO(glider): refactor this code.
if (!my_virt_addr_valid(addr)) {
// TODO(glider): Trinity is able to trigger the check below with size=14240.
ENTER_RUNTIME(irq_flags);
page = vmalloc_to_page_or_null(addr);
if (page) {
LEAVE_RUNTIME(irq_flags);
goto next;
}
WARN(1, "kmsan_get_shadow_address_inline(%px, %d, %d)\n", addr, size, checked);
if (checked) {
BUG();
} else {
LEAVE_RUNTIME(irq_flags);
return NULL;
}
}
page = virt_to_page(addr);
if (!page)
return NULL;
next:
if (!(page->shadow)) {
ENTER_RUNTIME(irq_flags);
oops_in_progress = 1;
kmsan_pr_err("not allocated shadow for addr %px (page %px)\n", addr, page);
BUG();
LEAVE_RUNTIME(irq_flags);
}
offset = addr % PAGE_SIZE;
if ((offset + size - 1 > PAGE_SIZE)) {
/* The access overflows the current page and touches the next
* one. Make sure the shadow pages are also consequent.
*/
if (!metadata_is_contiguous(addr, size, /*is_origin*/false)) {
return NULL;
}
}
ret = page_address(page->shadow) + offset;
return ret;
}
/* kmsan_get_origin_address_noruntime() must not be called from within runtime. */
inline
void *kmsan_get_origin_address_inline(u64 addr, size_t size)
{
struct page *page, *next_page;
unsigned long offset, shadow_size;
void *ret;
depot_stack_handle_t origin;
unsigned long irq_flags;
size_t pad;
// TODO(glider): For some reason vmalloc'ed addresses aren't considered valid.
if (!IS_ALIGNED(addr, 4)) {
pad = addr % 4;
addr -= pad;
size += pad;
}
// TODO(glider): refactor this code.
if (!my_virt_addr_valid(addr)) {
// TODO(glider): Trinity is able to trigger the check below with size=14240.
// No point in increasing the dummy origin size further.
ENTER_RUNTIME(irq_flags);
page = vmalloc_to_page_or_null(addr);
if (page) {
LEAVE_RUNTIME(irq_flags);
goto next;
}
WARN(1, "kmsan_get_origin_address_inline(%px, %d)\n", addr, size);
BUG();
}
page = virt_to_page(addr);
next:
if (!page || !(page->origin)) {
kmsan_pr_err("not allocated origin for addr %px (page %px)\n", addr, page);
BUG();
}
offset = addr % PAGE_SIZE;
ret = page_address(page->origin) + offset;
return ret;
}
#include <linux/highmem.h>
static noinline
shadow_origin_ptr_t msan_get_shadow_origin_ptr(u64 addr, u64 size, bool store)
{
shadow_origin_ptr_t ret;
void *shadow, *origin;
unsigned long irq_flags;
struct page *page, *next_page;
unsigned long offset;
size_t pad;
if (store) {
ret.s = dummy_shadow_store_page;
ret.o = dummy_origin_store_page;
} else {
ret.s = dummy_shadow_load_page;
ret.o = dummy_origin_load_page;
}
if (!kmsan_ready || IN_RUNTIME()) {
return ret;
}
if (size > PAGE_SIZE) {
WARN(1, "size too big in msan_get_shadow_origin_ptr(%px, %d, %d)\n", addr, size, store);
//BUG();
ret.s = NULL;
ret.o = NULL;
return ret;
}
if (!my_virt_addr_valid(addr)) {
ENTER_RUNTIME(irq_flags);
page = vmalloc_to_page_or_null(addr);
if (page) {
LEAVE_RUNTIME(irq_flags);
goto next;
}
LEAVE_RUNTIME(irq_flags);
return ret;
}
page = virt_to_page(addr);
next:
if ((!page) || (!(page->shadow))) {
return ret;
}
offset = addr % PAGE_SIZE;
if ((offset + size - 1 > PAGE_SIZE)) {
/* The access overflows the current page and touches the next
* one. Make sure the shadow pages are also consequent.
*/
if (!metadata_is_contiguous(addr, size, /*is_origin*/false)) {
return ret;
}
}
shadow = page_address(page->shadow) + offset;
if (!shadow)
goto leave;
ret.s = shadow;
// TODO(glider): For some reason vmalloc'ed addresses aren't considered valid.
if (!IS_ALIGNED(addr, 4)) {
pad = addr % 4;
addr -= pad;
}
offset = addr % PAGE_SIZE;
// Don't check origins, shadow should've checked already.
origin = page_address(page->origin) + offset;
// origin cannot be NULL, because shadow is already non-NULL.
BUG_ON(!origin);
ret.o = origin;
leave:
return ret;
}
shadow_origin_ptr_t __msan_metadata_ptr_for_load_n(u64 addr, u64 size)
{
return msan_get_shadow_origin_ptr(addr, size, /*store*/false);
}
EXPORT_SYMBOL(__msan_metadata_ptr_for_load_n);
shadow_origin_ptr_t __msan_metadata_ptr_for_store_n(u64 addr, u64 size)
{
return msan_get_shadow_origin_ptr(addr, size, /*store*/true);
}
EXPORT_SYMBOL(__msan_metadata_ptr_for_store_n);
#define DECLARE_METADATA_PTR_GETTER(size) \
shadow_origin_ptr_t __msan_metadata_ptr_for_load_##size(u64 addr) \
{ \
return msan_get_shadow_origin_ptr(addr, size, /*store*/false); \
} \
EXPORT_SYMBOL(__msan_metadata_ptr_for_load_##size); \
\
shadow_origin_ptr_t __msan_metadata_ptr_for_store_##size(u64 addr) \
{ \
return msan_get_shadow_origin_ptr(addr, size, /*store*/true); \
} \
EXPORT_SYMBOL(__msan_metadata_ptr_for_store_##size);
DECLARE_METADATA_PTR_GETTER(1);
DECLARE_METADATA_PTR_GETTER(2);
shadow_origin_ptr_t __msan_metadata_ptr_for_load_4(u64 addr)
{
return msan_get_shadow_origin_ptr(addr, 4, /*store*/false);
}
EXPORT_SYMBOL(__msan_metadata_ptr_for_load_4);
shadow_origin_ptr_t __msan_metadata_ptr_for_store_4(u64 addr)
{
return msan_get_shadow_origin_ptr(addr, 4, /*store*/true);
}
EXPORT_SYMBOL(__msan_metadata_ptr_for_store_4);
///DECLARE_METADATA_PTR_GETTER(4);
DECLARE_METADATA_PTR_GETTER(8);
void *__msan_memmove(void *dst, void *src, u64 n)
{
void *result;
void *shadow_dst;
unsigned long irq_flags;
result = __memmove(dst, src, n);
if (!n)
// Some people call memmove() with zero length.
return result;
if (IN_RUNTIME())
return result;
if (!kmsan_ready)
return result;
ENTER_RUNTIME(irq_flags);
// TODO(glider): due to a hack kmsan_get_shadow_address() may return NULL
// for addresses in vmalloc space.
// Or maybe it's enough to just skip copying invalid addresses?
/* Ok to skip address check here, we'll do it later. */
shadow_dst = (void*)kmsan_get_shadow_address((u64)dst, n, /*checked*/false, /*is_store*/true);
if (shadow_dst)
kmsan_memmove_shadow(dst, src, n);
else
kmsan_pr_err("__msan_memmove(%px, %px, %d): skipping shadow\n", dst, src, n);
// TODO(glider): origins.
// We may want to chain every |src| origin with the current stack.
kmsan_memmove_origins((u64)dst, (u64)src, n);
LEAVE_RUNTIME(irq_flags);
return result;
}
EXPORT_SYMBOL(__msan_memmove);
void *__msan_memcpy(void *dst, const void *src, u64 n)
{
void *result;
void *shadow_dst;
unsigned long irq_flags;
/*
* There are known cases where kernel code calls memcpy() with overlapping
* arguments (e.g. when user issues splice for overlapping file regions).
* So this is disabled for now.
*/
#if 0
if ((dst != src) && (!(((u64)dst + n <= (u64)src) || ((u64)src + n <= (u64)dst)))) {
kmsan_pr_err("==================================================================\n");
// TODO(glider): avoid __builtin_return_address(1).
kmsan_pr_err("WARNING: memcpy-param-overlap in %pS\n", __builtin_return_address(1));
kmsan_pr_err("__msan_memcpy(%px, %px, %d)\n", dst, src, n);
dump_stack();
kmsan_pr_err("==================================================================\n");
}
#endif
result = __memcpy(dst, src, n);
if (!n)
// Some people call memcpy() with zero length.
return result;
if (IN_RUNTIME())
return result;
if (!kmsan_ready)
return result;
ENTER_RUNTIME(irq_flags);
/* Ok to skip address check here, we'll do it later. */
shadow_dst = kmsan_get_shadow_address((u64)dst, n, /*checked*/false, /*is_store*/true);
// TODO(glider): due to a hack kmsan_get_shadow_address() may return NULL
// for addresses in vmalloc space.
// Or maybe it's enough to just skip copying invalid addresses?
if (shadow_dst)
kmsan_memcpy_shadow(dst, src, n);
else
kmsan_pr_err("__msan_memcpy(%px, %px, %d): skipping shadow\n", dst, src, n);
// TODO(glider): origins
// We may want to chain every |src| origin with the current stack.
kmsan_memcpy_origins((u64)dst, (u64)src, n);
leave:
LEAVE_RUNTIME(irq_flags);
return result;
}
EXPORT_SYMBOL(__msan_memcpy);
void *__msan_memset(void *dst, int c, size_t n)
{
void *result;
unsigned long irq_flags;
depot_stack_handle_t origin, new_origin;
unsigned int shadow;
void *caller;
result = __memset(dst, c, n);
if (IN_RUNTIME())
return result;
if (!kmsan_ready)
return result;
ENTER_RUNTIME(irq_flags);
// TODO(glider): emit stores to param_tls and param_origin_tls in the compiler for KMSAN.
// (not for MSan, because __msan_memset could be called from the userspace RTL)
// Take the shadow and origin of |c|.
///shadow = (unsigned int)(current->kmsan.cstate.param_tls[1]);
///origin = (depot_stack_handle_t)(current->kmsan.cstate.param_origin_tls[1]);
shadow = 0;
kmsan_internal_memset_shadow((u64)dst, shadow, n);
///new_origin = kmsan_internal_chain_origin(origin, /*full*/true);
new_origin = 0;
kmsan_set_origin((u64)dst, n, new_origin);
LEAVE_RUNTIME(irq_flags);
return result;
}
EXPORT_SYMBOL(__msan_memset);
depot_stack_handle_t __msan_chain_origin(depot_stack_handle_t origin)
{
depot_stack_handle_t ret = 0;
unsigned long irq_flags;
if (IN_RUNTIME())
return ret;
if (!kmsan_ready)
return ret;
ENTER_RUNTIME(irq_flags);
ret = kmsan_internal_chain_origin(origin, /*full*/true);
LEAVE_RUNTIME(irq_flags);
return ret;
}
EXPORT_SYMBOL(__msan_chain_origin);
inline void kmsan_internal_memset_shadow_inline(u64 address, int b, size_t size)
{
void *shadow_start;
u64 page_offset;
size_t to_fill;
if (!kmsan_ready) {
// No need to fill the dummy shadow.
return;
}
while (size) {
page_offset = address % PAGE_SIZE;
to_fill = min_num(PAGE_SIZE - page_offset, size);
shadow_start = kmsan_get_shadow_address(address, to_fill, /*checked*/true, /*is_store*/true);
if (!shadow_start) {
current->kmsan.is_reporting = true;
kmsan_pr_err("WARNING: not poisoning %d bytes starting at %px, because the shadow is NULL\n", to_fill, address);
current->kmsan.is_reporting = false;
BUG();
}
__memset(shadow_start, b, to_fill);
address += to_fill;
size -= to_fill;
}
}
inline
void kmsan_write_aligned_origin_inline(const void *var, size_t size, u32 origin)
{
u32 *var_cast = (u32 *)var;
int i;
BUG_ON((u64)var_cast % 4);
BUG_ON(size % 4);
for (i = 0; i < size / 4; i++)
var_cast[i] = origin;
}
inline void kmsan_set_origin_inline(u64 address, int size, u32 origin)
{
void *origin_start;
u64 page_offset;
size_t to_fill, pad = 0;
if (!IS_ALIGNED(address, 4)) {
pad = address % 4;
address -= pad;
size += pad;
}
while (size > 0) {
page_offset = address % PAGE_SIZE;
to_fill = (PAGE_SIZE - page_offset > size) ? size : PAGE_SIZE - page_offset;
to_fill = ALIGN(to_fill, 4); // at least 4 bytes
BUG_ON(!to_fill);
// Don't check
origin_start = kmsan_get_origin_address_noruntime(address, to_fill, false);
if (!origin_start) {
current->kmsan.is_reporting = true;
kmsan_pr_err("WARNING: not setting origing for %d bytes starting at %px, because the origin is NULL\n", to_fill, address);
current->kmsan.is_reporting = false;
BUG();
}
kmsan_write_aligned_origin_inline(origin_start, to_fill, origin);
address += to_fill;
size -= to_fill;
}
}
void __msan_poison_alloca(u64 address, u64 size, char *descr/*checked*/, u64 pc)
{
depot_stack_handle_t handle;
unsigned long entries[4];
struct stack_trace trace = {
.nr_entries = 4,
.entries = entries,
.max_entries = 4,
.skip = 0
};
unsigned long irq_flags;
u64 size_copy = size, to_fill;
u64 addr_copy = address;
u64 page_offset;
void *shadow_start;
if (!kmsan_ready)
return;
if (IN_RUNTIME())
return;
///inlining this:
///kmsan_internal_memset_shadow_inline((u64)address, -1, (size_t)size);
while (size_copy) {
page_offset = addr_copy % PAGE_SIZE;
to_fill = min_num(PAGE_SIZE - page_offset, size_copy);
shadow_start = kmsan_get_shadow_address_inline(addr_copy, to_fill, true);
if (!shadow_start) {
current->kmsan.is_reporting = true;
kmsan_pr_err("WARNING: not poisoning %d bytes starting at %px, because the shadow is NULL\n", to_fill, addr_copy);
current->kmsan.is_reporting = false;
BUG();
}
__memset(shadow_start, -1, to_fill);
addr_copy += to_fill;
size_copy -= to_fill;
}
entries[0] = KMSAN_ALLOCA_MAGIC_ORIGIN;
entries[1] = (u64)descr;
entries[2] = __builtin_return_address(0);
entries[3] = pc;
ENTER_RUNTIME(irq_flags);
handle = depot_save_stack(&trace, GFP_ATOMIC);
LEAVE_RUNTIME(irq_flags);
// TODO(glider): just a plain origin description isn't enough, let's store the full stack here.
///handle = kmsan_internal_chain_origin(handle, /*full*/true);
kmsan_set_origin_inline(address, size, handle);
}
EXPORT_SYMBOL(__msan_poison_alloca);
void __msan_unpoison_alloca(void *address, u64 size)
{
unsigned long irq_flags;
if (!kmsan_ready)
return;
if (IN_RUNTIME())
return;
ENTER_RUNTIME(irq_flags);
kmsan_internal_unpoison_shadow(address, size);
LEAVE_RUNTIME(irq_flags);
}
EXPORT_SYMBOL(__msan_unpoison_alloca);
// Compiler API
void __msan_warning_32(u32 origin)
{
void *caller;
unsigned long irq_flags;
if (!kmsan_ready)
return;
if (IN_RUNTIME())
return;
ENTER_RUNTIME(irq_flags);
caller = __builtin_return_address(0);
kmsan_report(caller, origin, /*address*/0, /*size*/0,
/*off_first*/0, /*off_last*/0, /*deep*/false, REASON_ANY);
LEAVE_RUNTIME(irq_flags);
}
EXPORT_SYMBOL(__msan_warning_32);
// Per-task getters.
kmsan_context_state *__msan_get_context_state(void)
{
unsigned long irq_flags;
kmsan_context_state *ret;
if (!kmsan_threads_ready) {
__memset(&kmsan_dummy_state, 0, sizeof(kmsan_dummy_state));
return &kmsan_dummy_state;
}
__msan_init();
if (IN_RUNTIME() || !current->kmsan.enabled) {
// We're in runtime, don't care about the shadow.
return &kmsan_dummy_state;
}
// No need to enter/leave runtime?
ENTER_RUNTIME(irq_flags);
ret = task_kmsan_context_state();
LEAVE_RUNTIME(irq_flags);
BUG_ON(!ret);
return ret;
}
EXPORT_SYMBOL(__msan_get_context_state);