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
|
// SPDX-License-Identifier: GPL-2.0
/*
* functions to patch RO kernel text during runtime
*
* Copyright (c) 2019 Sven Schnelle <svens@stackframe.org>
*/
#include <linux/kernel.h>
#include <linux/spinlock.h>
#include <linux/kprobes.h>
#include <linux/mm.h>
#include <linux/stop_machine.h>
#include <asm/cacheflush.h>
#include <asm/fixmap.h>
#include <asm/patch.h>
struct patch {
void *addr;
u32 *insn;
unsigned int len;
};
static DEFINE_RAW_SPINLOCK(patch_lock);
static void __kprobes *patch_map(void *addr, int fixmap, int *need_unmap)
unsigned long uintaddr = (uintptr_t) addr;
bool module = !core_kernel_text(uintaddr);
struct page *page;
*need_unmap = 0;
if (module && IS_ENABLED(CONFIG_STRICT_MODULE_RWX))
page = vmalloc_to_page(addr);
else if (!module && IS_ENABLED(CONFIG_STRICT_KERNEL_RWX))
page = virt_to_page(addr);
else
return addr;
*need_unmap = 1;
set_fixmap(fixmap, page_to_phys(page));
return (void *) (__fix_to_virt(fixmap) + (uintaddr & ~PAGE_MASK));
}
static void __kprobes patch_unmap(int fixmap)
{
clear_fixmap(fixmap);
}
void __kprobes __patch_text_multiple(void *addr, u32 *insn, unsigned int len)
{
unsigned long start = (unsigned long)addr;
unsigned long end = (unsigned long)addr + len;
u32 *p, *fixmap;
int mapped;
/* Make sure we don't have any aliases in cache */
flush_kernel_vmap_range(addr, len);
flush_icache_range(start, end);
p = fixmap = patch_map(addr, FIX_TEXT_POKE0, &mapped);
while (len >= 4) {
*p++ = *insn++;
addr += sizeof(u32);
len -= sizeof(u32);
if (len && offset_in_page(addr) == 0) {
/*
* We're crossing a page boundary, so
* need to remap
*/
flush_kernel_vmap_range((void *)fixmap,
(p-fixmap) * sizeof(*p));
if (mapped)
patch_unmap(FIX_TEXT_POKE0);
p = fixmap = patch_map(addr, FIX_TEXT_POKE0, &mapped);
}
}
flush_kernel_vmap_range((void *)fixmap, (p-fixmap) * sizeof(*p));
if (mapped)
patch_unmap(FIX_TEXT_POKE0);
flush_icache_range(start, end);
}
void __kprobes __patch_text(void *addr, u32 insn)
{
__patch_text_multiple(addr, &insn, sizeof(insn));
}
static int __kprobes patch_text_stop_machine(void *data)
{
struct patch *patch = data;
__patch_text_multiple(patch->addr, patch->insn, patch->len);
return 0;
}
void __kprobes patch_text(void *addr, unsigned int insn)
{
struct patch patch = {
.addr = addr,
.insn = &insn,
.len = sizeof(insn),
};
stop_machine_cpuslocked(patch_text_stop_machine, &patch, NULL);
}
void __kprobes patch_text_multiple(void *addr, u32 *insn, unsigned int len)
{
struct patch patch = {
.addr = addr,
.insn = insn,
.len = len
};
stop_machine_cpuslocked(patch_text_stop_machine, &patch, NULL);
}
|
