[mirror_ubuntu-jammy-kernel.git] / mm / kasan / 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];
}
Commit	Line	Data
2e903b91 AK	1	// SPDX-License-Identifier: GPL-2.0
	2	/*
	3	* This file contains core hardware tag-based KASAN code.
	4	*
	5	* Copyright (c) 2020 Google, Inc.
	6	* Author: Andrey Konovalov <andreyknvl@google.com>
	7	*/
	8
	9	#define pr_fmt(fmt) "kasan: " fmt
	10
8028caac	11	#include <linux/init.h>
2e903b91 AK	12	#include <linux/kasan.h>
	13	#include <linux/kernel.h>
	14	#include <linux/memory.h>
	15	#include <linux/mm.h>
8028caac	16	#include <linux/static_key.h>
2e903b91 AK	17	#include <linux/string.h>
	18	#include <linux/types.h>
	19
	20	#include "kasan.h"
	21
8028caac AK	22	enum kasan_arg_mode {
	23	KASAN_ARG_MODE_DEFAULT,
	24	KASAN_ARG_MODE_OFF,
	25	KASAN_ARG_MODE_PROD,
	26	KASAN_ARG_MODE_FULL,
	27	};
	28
	29	enum kasan_arg_stacktrace {
	30	KASAN_ARG_STACKTRACE_DEFAULT,
	31	KASAN_ARG_STACKTRACE_OFF,
	32	KASAN_ARG_STACKTRACE_ON,
	33	};
	34
	35	enum kasan_arg_fault {
	36	KASAN_ARG_FAULT_DEFAULT,
	37	KASAN_ARG_FAULT_REPORT,
	38	KASAN_ARG_FAULT_PANIC,
	39	};
	40
	41	static enum kasan_arg_mode kasan_arg_mode __ro_after_init;
	42	static enum kasan_arg_stacktrace kasan_arg_stacktrace __ro_after_init;
	43	static enum kasan_arg_fault kasan_arg_fault __ro_after_init;
	44
	45	/* Whether KASAN is enabled at all. */
	46	DEFINE_STATIC_KEY_FALSE(kasan_flag_enabled);
	47	EXPORT_SYMBOL(kasan_flag_enabled);
	48
	49	/* Whether to collect alloc/free stack traces. */
	50	DEFINE_STATIC_KEY_FALSE(kasan_flag_stacktrace);
	51
	52	/* Whether panic or disable tag checking on fault. */
	53	bool kasan_flag_panic __ro_after_init;
	54
	55	/* kasan.mode=off/prod/full */
	56	static int __init early_kasan_mode(char *arg)
	57	{
	58	if (!arg)
	59	return -EINVAL;
	60
	61	if (!strcmp(arg, "off"))
	62	kasan_arg_mode = KASAN_ARG_MODE_OFF;
	63	else if (!strcmp(arg, "prod"))
	64	kasan_arg_mode = KASAN_ARG_MODE_PROD;
	65	else if (!strcmp(arg, "full"))
	66	kasan_arg_mode = KASAN_ARG_MODE_FULL;
	67	else
	68	return -EINVAL;
	69
	70	return 0;
	71	}
	72	early_param("kasan.mode", early_kasan_mode);
	73
	74	/* kasan.stack=off/on */
	75	static int __init early_kasan_flag_stacktrace(char *arg)
	76	{
	77	if (!arg)
	78	return -EINVAL;
	79
	80	if (!strcmp(arg, "off"))
	81	kasan_arg_stacktrace = KASAN_ARG_STACKTRACE_OFF;
	82	else if (!strcmp(arg, "on"))
	83	kasan_arg_stacktrace = KASAN_ARG_STACKTRACE_ON;
	84	else
	85	return -EINVAL;
86
87	return 0;
88	}
89	early_param("kasan.stacktrace", early_kasan_flag_stacktrace);
90
91	/* kasan.fault=report/panic */
92	static int __init early_kasan_fault(char *arg)
93	{
94	if (!arg)
95	return -EINVAL;
96
97	if (!strcmp(arg, "report"))
98	kasan_arg_fault = KASAN_ARG_FAULT_REPORT;
99	else if (!strcmp(arg, "panic"))
100	kasan_arg_fault = KASAN_ARG_FAULT_PANIC;
101	else
102	return -EINVAL;
103
104	return 0;
105	}
106	early_param("kasan.fault", early_kasan_fault);
107
2e903b91 AK	108	/* kasan_init_hw_tags_cpu() is called for each CPU. */
	109	void kasan_init_hw_tags_cpu(void)
	110	{
8028caac AK	111	/*
	112	* There's no need to check that the hardware is MTE-capable here,
	113	* as this function is only called for MTE-capable hardware.
	114	*/
	115
	116	/* If KASAN is disabled, do nothing. */
	117	if (kasan_arg_mode == KASAN_ARG_MODE_OFF)
	118	return;
	119
2e903b91 AK	120	hw_init_tags(KASAN_TAG_MAX);
	121	hw_enable_tagging();
	122	}
	123
	124	/* kasan_init_hw_tags() is called once on boot CPU. */
	125	void __init kasan_init_hw_tags(void)
	126	{
8028caac AK	127	/* If hardware doesn't support MTE, do nothing. */
	128	if (!system_supports_mte())
	129	return;
	130
	131	/* Choose KASAN mode if kasan boot parameter is not provided. */
	132	if (kasan_arg_mode == KASAN_ARG_MODE_DEFAULT) {
	133	if (IS_ENABLED(CONFIG_DEBUG_KERNEL))
	134	kasan_arg_mode = KASAN_ARG_MODE_FULL;
	135	else
	136	kasan_arg_mode = KASAN_ARG_MODE_PROD;
	137	}
	138
	139	/* Preset parameter values based on the mode. */
	140	switch (kasan_arg_mode) {
	141	case KASAN_ARG_MODE_DEFAULT:
	142	/* Shouldn't happen as per the check above. */
	143	WARN_ON(1);
	144	return;
	145	case KASAN_ARG_MODE_OFF:
	146	/* If KASAN is disabled, do nothing. */
	147	return;
	148	case KASAN_ARG_MODE_PROD:
	149	static_branch_enable(&kasan_flag_enabled);
	150	break;
	151	case KASAN_ARG_MODE_FULL:
	152	static_branch_enable(&kasan_flag_enabled);
	153	static_branch_enable(&kasan_flag_stacktrace);
	154	break;
	155	}
	156
	157	/* Now, optionally override the presets. */
	158
	159	switch (kasan_arg_stacktrace) {
	160	case KASAN_ARG_STACKTRACE_DEFAULT:
	161	break;
	162	case KASAN_ARG_STACKTRACE_OFF:
	163	static_branch_disable(&kasan_flag_stacktrace);
	164	break;
	165	case KASAN_ARG_STACKTRACE_ON:
	166	static_branch_enable(&kasan_flag_stacktrace);
	167	break;
	168	}
	169
	170	switch (kasan_arg_fault) {
	171	case KASAN_ARG_FAULT_DEFAULT:
	172	break;
	173	case KASAN_ARG_FAULT_REPORT:
	174	kasan_flag_panic = false;
	175	break;
	176	case KASAN_ARG_FAULT_PANIC:
	177	kasan_flag_panic = true;
	178	break;
	179	}
	180
2e903b91 AK	181	pr_info("KernelAddressSanitizer initialized\n");
	182	}
	183
2e903b91 AK	184	void kasan_set_free_info(struct kmem_cache *cache,
	185	void *object, u8 tag)
	186	{
	187	struct kasan_alloc_meta *alloc_meta;
	188
6476792f	189	alloc_meta = kasan_get_alloc_meta(cache, object);
97593cad AK	190	if (alloc_meta)
97593cad AK	191	kasan_set_track(&alloc_meta->free_track[0], GFP_NOWAIT);
2e903b91 AK	192	}
	193
	194	struct kasan_track kasan_get_free_track(struct kmem_cache cache,
	195	void *object, u8 tag)
	196	{
	197	struct kasan_alloc_meta *alloc_meta;
	198
6476792f	199	alloc_meta = kasan_get_alloc_meta(cache, object);
97593cad AK	200	if (!alloc_meta)
	201	return NULL;
	202
2e903b91 AK	203	return &alloc_meta->free_track[0];
2e903b91 AK	204	}