1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
|
/*
* This file contains core tag-based KASAN code.
*
* Copyright (c) 2018 Google, Inc.
* Author: Andrey Konovalov <andreyknvl@google.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#define DISABLE_BRANCH_PROFILING
#include <linux/export.h>
#include <linux/interrupt.h>
#include <linux/init.h>
#include <linux/kasan.h>
#include <linux/kernel.h>
#include <linux/kmemleak.h>
#include <linux/linkage.h>
#include <linux/memblock.h>
#include <linux/memory.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/printk.h>
#include <linux/random.h>
#include <linux/sched.h>
#include <linux/sched/task_stack.h>
#include <linux/slab.h>
#include <linux/stacktrace.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/vmalloc.h>
#include <linux/bug.h>
#include "kasan.h"
#include "../slab.h"
static DEFINE_PER_CPU(u32, prng_state);
void kasan_init_tags(void)
{
int cpu;
for_each_possible_cpu(cpu)
per_cpu(prng_state, cpu) = get_random_u32();
}
/*
* If a preemption happens between this_cpu_read and this_cpu_write, the only
* side effect is that we'll give a few allocated in different contexts objects
* the same tag. Since tag-based KASAN is meant to be used a probabilistic
* bug-detection debug feature, this doesn't have significant negative impact.
*
* Ideally the tags use strong randomness to prevent any attempts to predict
* them during explicit exploit attempts. But strong randomness is expensive,
* and we did an intentional trade-off to use a PRNG. This non-atomic RMW
* sequence has in fact positive effect, since interrupts that randomly skew
* PRNG at unpredictable points do only good.
*/
u8 random_tag(void)
{
u32 state = this_cpu_read(prng_state);
state = 1664525 * state + 1013904223;
this_cpu_write(prng_state, state);
return (u8)(state % (KASAN_TAG_MAX + 1));
}
void *kasan_reset_tag(const void *addr)
{
return reset_tag(addr);
}
void check_memory_region(unsigned long addr, size_t size, bool write,
unsigned long ret_ip)
{
}
#define DEFINE_HWASAN_LOAD_STORE(size) \
void __hwasan_load##size##_noabort(unsigned long addr) \
{ \
} \
EXPORT_SYMBOL(__hwasan_load##size##_noabort); \
void __hwasan_store##size##_noabort(unsigned long addr) \
{ \
} \
EXPORT_SYMBOL(__hwasan_store##size##_noabort)
DEFINE_HWASAN_LOAD_STORE(1);
DEFINE_HWASAN_LOAD_STORE(2);
DEFINE_HWASAN_LOAD_STORE(4);
DEFINE_HWASAN_LOAD_STORE(8);
DEFINE_HWASAN_LOAD_STORE(16);
void __hwasan_loadN_noabort(unsigned long addr, unsigned long size)
{
}
EXPORT_SYMBOL(__hwasan_loadN_noabort);
void __hwasan_storeN_noabort(unsigned long addr, unsigned long size)
{
}
EXPORT_SYMBOL(__hwasan_storeN_noabort);
void __hwasan_tag_memory(unsigned long addr, u8 tag, unsigned long size)
{
}
EXPORT_SYMBOL(__hwasan_tag_memory);
|
