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
|
// SPDX-License-Identifier: GPL-2.0
// Copyright (C) 2018 Joe Lawrence <joe.lawrence@redhat.com>
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/livepatch.h>
#include <linux/slab.h>
/*
* Keep a small list of pointers so that we can print address-agnostic
* pointer values. Use a rolling integer count to differentiate the values.
* Ironically we could have used the shadow variable API to do this, but
* let's not lean too heavily on the very code we're testing.
*/
static LIST_HEAD(ptr_list);
struct shadow_ptr {
void *ptr;
int id;
struct list_head list;
};
static void free_ptr_list(void)
{
struct shadow_ptr *sp, *tmp_sp;
list_for_each_entry_safe(sp, tmp_sp, &ptr_list, list) {
list_del(&sp->list);
kfree(sp);
}
}
static int ptr_id(void *ptr)
{
struct shadow_ptr *sp;
static int count;
list_for_each_entry(sp, &ptr_list, list) {
if (sp->ptr == ptr)
return sp->id;
}
sp = kmalloc(sizeof(*sp), GFP_ATOMIC);
if (!sp)
return -1;
sp->ptr = ptr;
sp->id = count++;
list_add(&sp->list, &ptr_list);
return sp->id;
}
/*
* Shadow variable wrapper functions that echo the function and arguments
* to the kernel log for testing verification. Don't display raw pointers,
* but use the ptr_id() value instead.
*/
static void *shadow_get(void *obj, unsigned long id)
{
void *ret = klp_shadow_get(obj, id);
pr_info("klp_%s(obj=PTR%d, id=0x%lx) = PTR%d\n",
__func__, ptr_id(obj), id, ptr_id(ret));
return ret;
}
static void *shadow_alloc(void *obj, unsigned long id, size_t size,
gfp_t gfp_flags, klp_shadow_ctor_t ctor,
void *ctor_data)
{
void *ret = klp_shadow_alloc(obj, id, size, gfp_flags, ctor,
ctor_data);
pr_info("klp_%s(obj=PTR%d, id=0x%lx, size=%zx, gfp_flags=%pGg), ctor=PTR%d, ctor_data=PTR%d = PTR%d\n",
__func__, ptr_id(obj), id, size, &gfp_flags, ptr_id(ctor),
ptr_id(ctor_data), ptr_id(ret));
return ret;
}
static void *shadow_get_or_alloc(void *obj, unsigned long id, size_t size,
gfp_t gfp_flags, klp_shadow_ctor_t ctor,
void *ctor_data)
{
void *ret = klp_shadow_get_or_alloc(obj, id, size, gfp_flags, ctor,
ctor_data);
pr_info("klp_%s(obj=PTR%d, id=0x%lx, size=%zx, gfp_flags=%pGg), ctor=PTR%d, ctor_data=PTR%d = PTR%d\n",
__func__, ptr_id(obj), id, size, &gfp_flags, ptr_id(ctor),
ptr_id(ctor_data), ptr_id(ret));
return ret;
}
static void shadow_free(void *obj, unsigned long id, klp_shadow_dtor_t dtor)
{
klp_shadow_free(obj, id, dtor);
pr_info("klp_%s(obj=PTR%d, id=0x%lx, dtor=PTR%d)\n",
__func__, ptr_id(obj), id, ptr_id(dtor));
}
static void shadow_free_all(unsigned long id, klp_shadow_dtor_t dtor)
{
klp_shadow_free_all(id, dtor);
pr_info("klp_%s(id=0x%lx, dtor=PTR%d)\n",
__func__, id, ptr_id(dtor));
}
/* Shadow variable constructor - remember simple pointer data */
static int shadow_ctor(void *obj, void *shadow_data, void *ctor_data)
{
int **shadow_int = shadow_data;
*shadow_int = ctor_data;
pr_info("%s: PTR%d -> PTR%d\n",
__func__, ptr_id(shadow_int), ptr_id(ctor_data));
return 0;
}
static void shadow_dtor(void *obj, void *shadow_data)
{
pr_info("%s(obj=PTR%d, shadow_data=PTR%d)\n",
__func__, ptr_id(obj), ptr_id(shadow_data));
}
static int test_klp_shadow_vars_init(void)
{
void *obj = THIS_MODULE;
int id = 0x1234;
size_t size = sizeof(int *);
gfp_t gfp_flags = GFP_KERNEL;
int var1, var2, var3, var4;
int **sv1, **sv2, **sv3, **sv4;
void *ret;
ptr_id(NULL);
ptr_id(&var1);
ptr_id(&var2);
ptr_id(&var3);
ptr_id(&var4);
/*
* With an empty shadow variable hash table, expect not to find
* any matches.
*/
ret = shadow_get(obj, id);
if (!ret)
pr_info(" got expected NULL result\n");
/*
* Allocate a few shadow variables with different <obj> and <id>.
*/
sv1 = shadow_alloc(obj, id, size, gfp_flags, shadow_ctor, &var1);
sv2 = shadow_alloc(obj + 1, id, size, gfp_flags, shadow_ctor, &var2);
sv3 = shadow_alloc(obj, id + 1, size, gfp_flags, shadow_ctor, &var3);
/*
* Verify we can find our new shadow variables and that they point
* to expected data.
*/
ret = shadow_get(obj, id);
if (ret == sv1 && *sv1 == &var1)
pr_info(" got expected PTR%d -> PTR%d result\n",
ptr_id(sv1), ptr_id(*sv1));
ret = shadow_get(obj + 1, id);
if (ret == sv2 && *sv2 == &var2)
pr_info(" got expected PTR%d -> PTR%d result\n",
ptr_id(sv2), ptr_id(*sv2));
ret = shadow_get(obj, id + 1);
if (ret == sv3 && *sv3 == &var3)
pr_info(" got expected PTR%d -> PTR%d result\n",
ptr_id(sv3), ptr_id(*sv3));
/*
* Allocate or get a few more, this time with the same <obj>, <id>.
* The second invocation should return the same shadow var.
*/
sv4 = shadow_get_or_alloc(obj + 2, id, size, gfp_flags, shadow_ctor, &var4);
ret = shadow_get_or_alloc(obj + 2, id, size, gfp_flags, shadow_ctor, &var4);
if (ret == sv4 && *sv4 == &var4)
pr_info(" got expected PTR%d -> PTR%d result\n",
ptr_id(sv4), ptr_id(*sv4));
/*
* Free the <obj=*, id> shadow variables and check that we can no
* longer find them.
*/
shadow_free(obj, id, shadow_dtor); /* sv1 */
ret = shadow_get(obj, id);
if (!ret)
pr_info(" got expected NULL result\n");
shadow_free(obj + 1, id, shadow_dtor); /* sv2 */
ret = shadow_get(obj + 1, id);
if (!ret)
pr_info(" got expected NULL result\n");
shadow_free(obj + 2, id, shadow_dtor); /* sv4 */
ret = shadow_get(obj + 2, id);
if (!ret)
pr_info(" got expected NULL result\n");
/*
* We should still find an <id+1> variable.
*/
ret = shadow_get(obj, id + 1);
if (ret == sv3 && *sv3 == &var3)
pr_info(" got expected PTR%d -> PTR%d result\n",
ptr_id(sv3), ptr_id(*sv3));
/*
* Free all the <id+1> variables, too.
*/
shadow_free_all(id + 1, shadow_dtor); /* sv3 */
ret = shadow_get(obj, id);
if (!ret)
pr_info(" shadow_get() got expected NULL result\n");
free_ptr_list();
return 0;
}
static void test_klp_shadow_vars_exit(void)
{
}
module_init(test_klp_shadow_vars_init);
module_exit(test_klp_shadow_vars_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Joe Lawrence <joe.lawrence@redhat.com>");
MODULE_DESCRIPTION("Livepatch test: shadow variables");
|
