summaryrefslogtreecommitdiff
path: root/lib/livepatch/test_klp_state2.c
blob: c978ea4d5e67d51f6e2477e5162efad734cc35b4 (plain)
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
// SPDX-License-Identifier: GPL-2.0
// Copyright (C) 2019 SUSE

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/slab.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/printk.h>
#include <linux/livepatch.h>

#define CONSOLE_LOGLEVEL_STATE 1
/* Version 2 supports migration. */
#define CONSOLE_LOGLEVEL_STATE_VERSION 2

static const char *const module_state[] = {
	[MODULE_STATE_LIVE]	= "[MODULE_STATE_LIVE] Normal state",
	[MODULE_STATE_COMING]	= "[MODULE_STATE_COMING] Full formed, running module_init",
	[MODULE_STATE_GOING]	= "[MODULE_STATE_GOING] Going away",
	[MODULE_STATE_UNFORMED]	= "[MODULE_STATE_UNFORMED] Still setting it up",
};

static void callback_info(const char *callback, struct klp_object *obj)
{
	if (obj->mod)
		pr_info("%s: %s -> %s\n", callback, obj->mod->name,
			module_state[obj->mod->state]);
	else
		pr_info("%s: vmlinux\n", callback);
}

static struct klp_patch patch;

static int allocate_loglevel_state(void)
{
	struct klp_state *loglevel_state, *prev_loglevel_state;

	prev_loglevel_state = klp_get_prev_state(CONSOLE_LOGLEVEL_STATE);
	if (prev_loglevel_state) {
		pr_info("%s: space to store console_loglevel already allocated\n",
		__func__);
		return 0;
	}

	loglevel_state = klp_get_state(&patch, CONSOLE_LOGLEVEL_STATE);
	if (!loglevel_state)
		return -EINVAL;

	loglevel_state->data = kzalloc(sizeof(console_loglevel), GFP_KERNEL);
	if (!loglevel_state->data)
		return -ENOMEM;

	pr_info("%s: allocating space to store console_loglevel\n",
		__func__);
	return 0;
}

static void fix_console_loglevel(void)
{
	struct klp_state *loglevel_state, *prev_loglevel_state;

	loglevel_state = klp_get_state(&patch, CONSOLE_LOGLEVEL_STATE);
	if (!loglevel_state)
		return;

	prev_loglevel_state = klp_get_prev_state(CONSOLE_LOGLEVEL_STATE);
	if (prev_loglevel_state) {
		pr_info("%s: taking over the console_loglevel change\n",
		__func__);
		loglevel_state->data = prev_loglevel_state->data;
		return;
	}

	pr_info("%s: fixing console_loglevel\n", __func__);
	*(int *)loglevel_state->data = console_loglevel;
	console_loglevel = CONSOLE_LOGLEVEL_MOTORMOUTH;
}

static void restore_console_loglevel(void)
{
	struct klp_state *loglevel_state, *prev_loglevel_state;

	prev_loglevel_state = klp_get_prev_state(CONSOLE_LOGLEVEL_STATE);
	if (prev_loglevel_state) {
		pr_info("%s: passing the console_loglevel change back to the old livepatch\n",
		__func__);
		return;
	}

	loglevel_state = klp_get_state(&patch, CONSOLE_LOGLEVEL_STATE);
	if (!loglevel_state)
		return;

	pr_info("%s: restoring console_loglevel\n", __func__);
	console_loglevel = *(int *)loglevel_state->data;
}

static void free_loglevel_state(void)
{
	struct klp_state *loglevel_state, *prev_loglevel_state;

	prev_loglevel_state = klp_get_prev_state(CONSOLE_LOGLEVEL_STATE);
	if (prev_loglevel_state) {
		pr_info("%s: keeping space to store console_loglevel\n",
		__func__);
		return;
	}

	loglevel_state = klp_get_state(&patch, CONSOLE_LOGLEVEL_STATE);
	if (!loglevel_state)
		return;

	pr_info("%s: freeing space for the stored console_loglevel\n",
		__func__);
	kfree(loglevel_state->data);
}

/* Executed on object patching (ie, patch enablement) */
static int pre_patch_callback(struct klp_object *obj)
{
	callback_info(__func__, obj);
	return allocate_loglevel_state();
}

/* Executed on object unpatching (ie, patch disablement) */
static void post_patch_callback(struct klp_object *obj)
{
	callback_info(__func__, obj);
	fix_console_loglevel();
}

/* Executed on object unpatching (ie, patch disablement) */
static void pre_unpatch_callback(struct klp_object *obj)
{
	callback_info(__func__, obj);
	restore_console_loglevel();
}

/* Executed on object unpatching (ie, patch disablement) */
static void post_unpatch_callback(struct klp_object *obj)
{
	callback_info(__func__, obj);
	free_loglevel_state();
}

static struct klp_func no_funcs[] = {
	{}
};

static struct klp_object objs[] = {
	{
		.name = NULL,	/* vmlinux */
		.funcs = no_funcs,
		.callbacks = {
			.pre_patch = pre_patch_callback,
			.post_patch = post_patch_callback,
			.pre_unpatch = pre_unpatch_callback,
			.post_unpatch = post_unpatch_callback,
		},
	}, { }
};

static struct klp_state states[] = {
	{
		.id = CONSOLE_LOGLEVEL_STATE,
		.version = CONSOLE_LOGLEVEL_STATE_VERSION,
	}, { }
};

static struct klp_patch patch = {
	.mod = THIS_MODULE,
	.objs = objs,
	.states = states,
	.replace = true,
};

static int test_klp_callbacks_demo_init(void)
{
	return klp_enable_patch(&patch);
}

static void test_klp_callbacks_demo_exit(void)
{
}

module_init(test_klp_callbacks_demo_init);
module_exit(test_klp_callbacks_demo_exit);
MODULE_LICENSE("GPL");
MODULE_INFO(livepatch, "Y");
MODULE_AUTHOR("Petr Mladek <pmladek@suse.com>");
MODULE_DESCRIPTION("Livepatch test: system state modification");