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