https://github.com/torvalds/linux
Tip revision: 5c8fe583cce542aa0b84adc939ce85293de36e5e authored by Linus Torvalds on 27 December 2020, 23:30:22 UTC
Linux 5.11-rc1
Linux 5.11-rc1
Tip revision: 5c8fe58
hw_tags.c
// SPDX-License-Identifier: GPL-2.0
/*
* This file contains core hardware tag-based KASAN code.
*
* Copyright (c) 2020 Google, Inc.
* Author: Andrey Konovalov <andreyknvl@google.com>
*/
#define pr_fmt(fmt) "kasan: " fmt
#include <linux/init.h>
#include <linux/kasan.h>
#include <linux/kernel.h>
#include <linux/memory.h>
#include <linux/mm.h>
#include <linux/static_key.h>
#include <linux/string.h>
#include <linux/types.h>
#include "kasan.h"
enum kasan_arg_mode {
KASAN_ARG_MODE_DEFAULT,
KASAN_ARG_MODE_OFF,
KASAN_ARG_MODE_PROD,
KASAN_ARG_MODE_FULL,
};
enum kasan_arg_stacktrace {
KASAN_ARG_STACKTRACE_DEFAULT,
KASAN_ARG_STACKTRACE_OFF,
KASAN_ARG_STACKTRACE_ON,
};
enum kasan_arg_fault {
KASAN_ARG_FAULT_DEFAULT,
KASAN_ARG_FAULT_REPORT,
KASAN_ARG_FAULT_PANIC,
};
static enum kasan_arg_mode kasan_arg_mode __ro_after_init;
static enum kasan_arg_stacktrace kasan_arg_stacktrace __ro_after_init;
static enum kasan_arg_fault kasan_arg_fault __ro_after_init;
/* Whether KASAN is enabled at all. */
DEFINE_STATIC_KEY_FALSE(kasan_flag_enabled);
EXPORT_SYMBOL(kasan_flag_enabled);
/* Whether to collect alloc/free stack traces. */
DEFINE_STATIC_KEY_FALSE(kasan_flag_stacktrace);
/* Whether panic or disable tag checking on fault. */
bool kasan_flag_panic __ro_after_init;
/* kasan.mode=off/prod/full */
static int __init early_kasan_mode(char *arg)
{
if (!arg)
return -EINVAL;
if (!strcmp(arg, "off"))
kasan_arg_mode = KASAN_ARG_MODE_OFF;
else if (!strcmp(arg, "prod"))
kasan_arg_mode = KASAN_ARG_MODE_PROD;
else if (!strcmp(arg, "full"))
kasan_arg_mode = KASAN_ARG_MODE_FULL;
else
return -EINVAL;
return 0;
}
early_param("kasan.mode", early_kasan_mode);
/* kasan.stack=off/on */
static int __init early_kasan_flag_stacktrace(char *arg)
{
if (!arg)
return -EINVAL;
if (!strcmp(arg, "off"))
kasan_arg_stacktrace = KASAN_ARG_STACKTRACE_OFF;
else if (!strcmp(arg, "on"))
kasan_arg_stacktrace = KASAN_ARG_STACKTRACE_ON;
else
return -EINVAL;
return 0;
}
early_param("kasan.stacktrace", early_kasan_flag_stacktrace);
/* kasan.fault=report/panic */
static int __init early_kasan_fault(char *arg)
{
if (!arg)
return -EINVAL;
if (!strcmp(arg, "report"))
kasan_arg_fault = KASAN_ARG_FAULT_REPORT;
else if (!strcmp(arg, "panic"))
kasan_arg_fault = KASAN_ARG_FAULT_PANIC;
else
return -EINVAL;
return 0;
}
early_param("kasan.fault", early_kasan_fault);
/* kasan_init_hw_tags_cpu() is called for each CPU. */
void kasan_init_hw_tags_cpu(void)
{
/*
* There's no need to check that the hardware is MTE-capable here,
* as this function is only called for MTE-capable hardware.
*/
/* If KASAN is disabled, do nothing. */
if (kasan_arg_mode == KASAN_ARG_MODE_OFF)
return;
hw_init_tags(KASAN_TAG_MAX);
hw_enable_tagging();
}
/* kasan_init_hw_tags() is called once on boot CPU. */
void __init kasan_init_hw_tags(void)
{
/* If hardware doesn't support MTE, do nothing. */
if (!system_supports_mte())
return;
/* Choose KASAN mode if kasan boot parameter is not provided. */
if (kasan_arg_mode == KASAN_ARG_MODE_DEFAULT) {
if (IS_ENABLED(CONFIG_DEBUG_KERNEL))
kasan_arg_mode = KASAN_ARG_MODE_FULL;
else
kasan_arg_mode = KASAN_ARG_MODE_PROD;
}
/* Preset parameter values based on the mode. */
switch (kasan_arg_mode) {
case KASAN_ARG_MODE_DEFAULT:
/* Shouldn't happen as per the check above. */
WARN_ON(1);
return;
case KASAN_ARG_MODE_OFF:
/* If KASAN is disabled, do nothing. */
return;
case KASAN_ARG_MODE_PROD:
static_branch_enable(&kasan_flag_enabled);
break;
case KASAN_ARG_MODE_FULL:
static_branch_enable(&kasan_flag_enabled);
static_branch_enable(&kasan_flag_stacktrace);
break;
}
/* Now, optionally override the presets. */
switch (kasan_arg_stacktrace) {
case KASAN_ARG_STACKTRACE_DEFAULT:
break;
case KASAN_ARG_STACKTRACE_OFF:
static_branch_disable(&kasan_flag_stacktrace);
break;
case KASAN_ARG_STACKTRACE_ON:
static_branch_enable(&kasan_flag_stacktrace);
break;
}
switch (kasan_arg_fault) {
case KASAN_ARG_FAULT_DEFAULT:
break;
case KASAN_ARG_FAULT_REPORT:
kasan_flag_panic = false;
break;
case KASAN_ARG_FAULT_PANIC:
kasan_flag_panic = true;
break;
}
pr_info("KernelAddressSanitizer initialized\n");
}
void kasan_set_free_info(struct kmem_cache *cache,
void *object, u8 tag)
{
struct kasan_alloc_meta *alloc_meta;
alloc_meta = kasan_get_alloc_meta(cache, object);
if (alloc_meta)
kasan_set_track(&alloc_meta->free_track[0], GFP_NOWAIT);
}
struct kasan_track *kasan_get_free_track(struct kmem_cache *cache,
void *object, u8 tag)
{
struct kasan_alloc_meta *alloc_meta;
alloc_meta = kasan_get_alloc_meta(cache, object);
if (!alloc_meta)
return NULL;
return &alloc_meta->free_track[0];
}