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
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
|
/*
* This file contains kasan initialization code for ARM64.
*
* Copyright (c) 2015 Samsung Electronics Co., Ltd.
* Author: Andrey Ryabinin <ryabinin.a.a@gmail.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) "kasan: " fmt
#include <linux/bootmem.h>
#include <linux/kasan.h>
#include <linux/kernel.h>
#include <linux/sched/task.h>
#include <linux/memblock.h>
#include <linux/start_kernel.h>
#include <linux/mm.h>
#include <asm/mmu_context.h>
#include <asm/kernel-pgtable.h>
#include <asm/page.h>
#include <asm/pgalloc.h>
#include <asm/pgtable.h>
#include <asm/sections.h>
#include <asm/tlbflush.h>
static pgd_t tmp_pg_dir[PTRS_PER_PGD] __initdata __aligned(PGD_SIZE);
/*
* The p*d_populate functions call virt_to_phys implicitly so they can't be used
* directly on kernel symbols (bm_p*d). All the early functions are called too
* early to use lm_alias so __p*d_populate functions must be used to populate
* with the physical address from __pa_symbol.
*/
static phys_addr_t __init kasan_alloc_zeroed_page(int node)
{
void *p = memblock_virt_alloc_try_nid(PAGE_SIZE, PAGE_SIZE,
__pa(MAX_DMA_ADDRESS),
MEMBLOCK_ALLOC_ACCESSIBLE, node);
return __pa(p);
}
static pte_t *__init kasan_pte_offset(pmd_t *pmdp, unsigned long addr, int node,
bool early)
{
if (pmd_none(READ_ONCE(*pmdp))) {
phys_addr_t pte_phys = early ? __pa_symbol(kasan_zero_pte)
: kasan_alloc_zeroed_page(node);
__pmd_populate(pmdp, pte_phys, PMD_TYPE_TABLE);
}
return early ? pte_offset_kimg(pmdp, addr)
: pte_offset_kernel(pmdp, addr);
}
static pmd_t *__init kasan_pmd_offset(pud_t *pudp, unsigned long addr, int node,
bool early)
{
if (pud_none(READ_ONCE(*pudp))) {
phys_addr_t pmd_phys = early ? __pa_symbol(kasan_zero_pmd)
: kasan_alloc_zeroed_page(node);
__pud_populate(pudp, pmd_phys, PMD_TYPE_TABLE);
}
return early ? pmd_offset_kimg(pudp, addr) : pmd_offset(pudp, addr);
}
static pud_t *__init kasan_pud_offset(pgd_t *pgdp, unsigned long addr, int node,
bool early)
{
if (pgd_none(READ_ONCE(*pgdp))) {
phys_addr_t pud_phys = early ? __pa_symbol(kasan_zero_pud)
: kasan_alloc_zeroed_page(node);
__pgd_populate(pgdp, pud_phys, PMD_TYPE_TABLE);
}
return early ? pud_offset_kimg(pgdp, addr) : pud_offset(pgdp, addr);
}
static void __init kasan_pte_populate(pmd_t *pmdp, unsigned long addr,
unsigned long end, int node, bool early)
{
unsigned long next;
pte_t *ptep = kasan_pte_offset(pmdp, addr, node, early);
do {
phys_addr_t page_phys = early ? __pa_symbol(kasan_zero_page)
: kasan_alloc_zeroed_page(node);
next = addr + PAGE_SIZE;
set_pte(ptep, pfn_pte(__phys_to_pfn(page_phys), PAGE_KERNEL));
} while (ptep++, addr = next, addr != end && pte_none(READ_ONCE(*ptep)));
}
static void __init kasan_pmd_populate(pud_t *pudp, unsigned long addr,
unsigned long end, int node, bool early)
{
unsigned long next;
pmd_t *pmdp = kasan_pmd_offset(pudp, addr, node, early);
do {
next = pmd_addr_end(addr, end);
kasan_pte_populate(pmdp, addr, next, node, early);
} while (pmdp++, addr = next, addr != end && pmd_none(READ_ONCE(*pmdp)));
}
static void __init kasan_pud_populate(pgd_t *pgdp, unsigned long addr,
unsigned long end, int node, bool early)
{
unsigned long next;
pud_t *pudp = kasan_pud_offset(pgdp, addr, node, early);
do {
next = pud_addr_end(addr, end);
kasan_pmd_populate(pudp, addr, next, node, early);
} while (pudp++, addr = next, addr != end && pud_none(READ_ONCE(*pudp)));
}
static void __init kasan_pgd_populate(unsigned long addr, unsigned long end,
int node, bool early)
{
unsigned long next;
pgd_t *pgdp;
pgdp = pgd_offset_k(addr);
do {
next = pgd_addr_end(addr, end);
kasan_pud_populate(pgdp, addr, next, node, early);
} while (pgdp++, addr = next, addr != end);
}
/* The early shadow maps everything to a single page of zeroes */
asmlinkage void __init kasan_early_init(void)
{
BUILD_BUG_ON(KASAN_SHADOW_OFFSET !=
KASAN_SHADOW_END - (1UL << (64 - KASAN_SHADOW_SCALE_SHIFT)));
BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_START, PGDIR_SIZE));
BUILD_BUG_ON(!IS_ALIGNED(KASAN_SHADOW_END, PGDIR_SIZE));
kasan_pgd_populate(KASAN_SHADOW_START, KASAN_SHADOW_END, NUMA_NO_NODE,
true);
}
/* Set up full kasan mappings, ensuring that the mapped pages are zeroed */
static void __init kasan_map_populate(unsigned long start, unsigned long end,
int node)
{
kasan_pgd_populate(start & PAGE_MASK, PAGE_ALIGN(end), node, false);
}
/*
* Copy the current shadow region into a new pgdir.
*/
void __init kasan_copy_shadow(pgd_t *pgdir)
{
pgd_t *pgdp, *pgdp_new, *pgdp_end;
pgdp = pgd_offset_k(KASAN_SHADOW_START);
pgdp_end = pgd_offset_k(KASAN_SHADOW_END);
pgdp_new = pgd_offset_raw(pgdir, KASAN_SHADOW_START);
do {
set_pgd(pgdp_new, READ_ONCE(*pgdp));
} while (pgdp++, pgdp_new++, pgdp != pgdp_end);
}
static void __init clear_pgds(unsigned long start,
unsigned long end)
{
/*
* Remove references to kasan page tables from
* swapper_pg_dir. pgd_clear() can't be used
* here because it's nop on 2,3-level pagetable setups
*/
for (; start < end; start += PGDIR_SIZE)
set_pgd(pgd_offset_k(start), __pgd(0));
}
void __init kasan_init(void)
{
u64 kimg_shadow_start, kimg_shadow_end;
u64 mod_shadow_start, mod_shadow_end;
struct memblock_region *reg;
int i;
kimg_shadow_start = (u64)kasan_mem_to_shadow(_text) & PAGE_MASK;
kimg_shadow_end = PAGE_ALIGN((u64)kasan_mem_to_shadow(_end));
mod_shadow_start = (u64)kasan_mem_to_shadow((void *)MODULES_VADDR);
mod_shadow_end = (u64)kasan_mem_to_shadow((void *)MODULES_END);
/*
* We are going to perform proper setup of shadow memory.
* At first we should unmap early shadow (clear_pgds() call bellow).
* However, instrumented code couldn't execute without shadow memory.
* tmp_pg_dir used to keep early shadow mapped until full shadow
* setup will be finished.
*/
memcpy(tmp_pg_dir, swapper_pg_dir, sizeof(tmp_pg_dir));
dsb(ishst);
cpu_replace_ttbr1(lm_alias(tmp_pg_dir));
clear_pgds(KASAN_SHADOW_START, KASAN_SHADOW_END);
kasan_map_populate(kimg_shadow_start, kimg_shadow_end,
pfn_to_nid(virt_to_pfn(lm_alias(_text))));
kasan_populate_zero_shadow((void *)KASAN_SHADOW_START,
(void *)mod_shadow_start);
kasan_populate_zero_shadow((void *)kimg_shadow_end,
kasan_mem_to_shadow((void *)PAGE_OFFSET));
if (kimg_shadow_start > mod_shadow_end)
kasan_populate_zero_shadow((void *)mod_shadow_end,
(void *)kimg_shadow_start);
for_each_memblock(memory, reg) {
void *start = (void *)__phys_to_virt(reg->base);
void *end = (void *)__phys_to_virt(reg->base + reg->size);
if (start >= end)
break;
kasan_map_populate((unsigned long)kasan_mem_to_shadow(start),
(unsigned long)kasan_mem_to_shadow(end),
pfn_to_nid(virt_to_pfn(start)));
}
/*
* KAsan may reuse the contents of kasan_zero_pte directly, so we
* should make sure that it maps the zero page read-only.
*/
for (i = 0; i < PTRS_PER_PTE; i++)
set_pte(&kasan_zero_pte[i],
pfn_pte(sym_to_pfn(kasan_zero_page), PAGE_KERNEL_RO));
memset(kasan_zero_page, 0, PAGE_SIZE);
cpu_replace_ttbr1(lm_alias(swapper_pg_dir));
/* At this point kasan is fully initialized. Enable error messages */
init_task.kasan_depth = 0;
pr_info("KernelAddressSanitizer initialized\n");
}
|
