1 // SPDX-License-Identifier: GPL-2.0
3 * This file contains core hardware tag-based KASAN code.
5 * Copyright (c) 2020 Google, Inc.
6 * Author: Andrey Konovalov <andreyknvl@google.com>
9 #define pr_fmt(fmt) "kasan: " fmt
11 #include <linux/init.h>
12 #include <linux/kasan.h>
13 #include <linux/kernel.h>
14 #include <linux/memory.h>
16 #include <linux/static_key.h>
17 #include <linux/string.h>
18 #include <linux/types.h>
23 KASAN_ARG_MODE_DEFAULT,
29 enum kasan_arg_stacktrace {
30 KASAN_ARG_STACKTRACE_DEFAULT,
31 KASAN_ARG_STACKTRACE_OFF,
32 KASAN_ARG_STACKTRACE_ON,
35 enum kasan_arg_fault {
36 KASAN_ARG_FAULT_DEFAULT,
37 KASAN_ARG_FAULT_REPORT,
38 KASAN_ARG_FAULT_PANIC,
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;
45 /* Whether KASAN is enabled at all. */
46 DEFINE_STATIC_KEY_FALSE(kasan_flag_enabled);
47 EXPORT_SYMBOL(kasan_flag_enabled);
49 /* Whether to collect alloc/free stack traces. */
50 DEFINE_STATIC_KEY_FALSE(kasan_flag_stacktrace);
52 /* Whether panic or disable tag checking on fault. */
53 bool kasan_flag_panic __ro_after_init;
55 /* kasan.mode=off/prod/full */
56 static int __init early_kasan_mode(char *arg)
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;
72 early_param("kasan.mode", early_kasan_mode);
74 /* kasan.stack=off/on */
75 static int __init early_kasan_flag_stacktrace(char *arg)
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;
89 early_param("kasan.stacktrace", early_kasan_flag_stacktrace);
91 /* kasan.fault=report/panic */
92 static int __init early_kasan_fault(char *arg)
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;
106 early_param("kasan.fault", early_kasan_fault);
108 /* kasan_init_hw_tags_cpu() is called for each CPU. */
109 void kasan_init_hw_tags_cpu(void)
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.
116 /* If KASAN is disabled, do nothing. */
117 if (kasan_arg_mode == KASAN_ARG_MODE_OFF)
120 hw_init_tags(KASAN_TAG_MAX);
124 /* kasan_init_hw_tags() is called once on boot CPU. */
125 void __init kasan_init_hw_tags(void)
127 /* If hardware doesn't support MTE, do nothing. */
128 if (!system_supports_mte())
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;
136 kasan_arg_mode = KASAN_ARG_MODE_PROD;
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. */
145 case KASAN_ARG_MODE_OFF:
146 /* If KASAN is disabled, do nothing. */
148 case KASAN_ARG_MODE_PROD:
149 static_branch_enable(&kasan_flag_enabled);
151 case KASAN_ARG_MODE_FULL:
152 static_branch_enable(&kasan_flag_enabled);
153 static_branch_enable(&kasan_flag_stacktrace);
157 /* Now, optionally override the presets. */
159 switch (kasan_arg_stacktrace) {
160 case KASAN_ARG_STACKTRACE_DEFAULT:
162 case KASAN_ARG_STACKTRACE_OFF:
163 static_branch_disable(&kasan_flag_stacktrace);
165 case KASAN_ARG_STACKTRACE_ON:
166 static_branch_enable(&kasan_flag_stacktrace);
170 switch (kasan_arg_fault) {
171 case KASAN_ARG_FAULT_DEFAULT:
173 case KASAN_ARG_FAULT_REPORT:
174 kasan_flag_panic = false;
176 case KASAN_ARG_FAULT_PANIC:
177 kasan_flag_panic = true;
181 pr_info("KernelAddressSanitizer initialized\n");
184 void kasan_set_free_info(struct kmem_cache *cache,
185 void *object, u8 tag)
187 struct kasan_alloc_meta *alloc_meta;
189 alloc_meta = kasan_get_alloc_meta(cache, object);
191 kasan_set_track(&alloc_meta->free_track[0], GFP_NOWAIT);
194 struct kasan_track *kasan_get_free_track(struct kmem_cache *cache,
195 void *object, u8 tag)
197 struct kasan_alloc_meta *alloc_meta;
199 alloc_meta = kasan_get_alloc_meta(cache, object);
203 return &alloc_meta->free_track[0];