linux-stable/mm/kasan/hw_tags.c
Andrey Konovalov 7169487bc2 kasan: clarify that only first bug is reported in HW_TAGS
Hwardware tag-based KASAN only reports the first found bug. After that MTE
tag checking gets disabled. Clarify this in comments and documentation.

Link: https://lkml.kernel.org/r/00383ba88a47c3f8342d12263c24bdf95527b07d.1612546384.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Marco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Branislav Rankov <Branislav.Rankov@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-02-26 09:41:03 -08:00

203 lines
4.5 KiB
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 {
KASAN_ARG_DEFAULT,
KASAN_ARG_OFF,
KASAN_ARG_ON,
};
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 kasan_arg __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 to panic or print a report and disable tag checking on fault. */
bool kasan_flag_panic __ro_after_init;
/* kasan=off/on */
static int __init early_kasan_flag(char *arg)
{
if (!arg)
return -EINVAL;
if (!strcmp(arg, "off"))
kasan_arg = KASAN_ARG_OFF;
else if (!strcmp(arg, "on"))
kasan_arg = KASAN_ARG_ON;
else
return -EINVAL;
return 0;
}
early_param("kasan", early_kasan_flag);
/* kasan.stacktrace=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 via command line, don't initialize it. */
if (kasan_arg == KASAN_ARG_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, don't initialize KASAN. */
if (!system_supports_mte())
return;
/* If KASAN is disabled via command line, don't initialize it. */
if (kasan_arg == KASAN_ARG_OFF)
return;
/* Enable KASAN. */
static_branch_enable(&kasan_flag_enabled);
switch (kasan_arg_stacktrace) {
case KASAN_ARG_STACKTRACE_DEFAULT:
/* Default to enabling stack trace collection. */
static_branch_enable(&kasan_flag_stacktrace);
break;
case KASAN_ARG_STACKTRACE_OFF:
/* Do nothing, kasan_flag_stacktrace keeps its default value. */
break;
case KASAN_ARG_STACKTRACE_ON:
static_branch_enable(&kasan_flag_stacktrace);
break;
}
switch (kasan_arg_fault) {
case KASAN_ARG_FAULT_DEFAULT:
/*
* Default to no panic on report.
* Do nothing, kasan_flag_panic keeps its default value.
*/
break;
case KASAN_ARG_FAULT_REPORT:
/* Do nothing, kasan_flag_panic keeps its default value. */
break;
case KASAN_ARG_FAULT_PANIC:
/* Enable panic on report. */
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];
}
#if IS_ENABLED(CONFIG_KASAN_KUNIT_TEST)
void kasan_set_tagging_report_once(bool state)
{
hw_set_tagging_report_once(state);
}
EXPORT_SYMBOL_GPL(kasan_set_tagging_report_once);
void kasan_enable_tagging(void)
{
hw_enable_tagging();
}
EXPORT_SYMBOL_GPL(kasan_enable_tagging);
#endif