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
|
// SPDX-License-Identifier: GPL-2.0
/* Lock down the kernel
*
* Copyright (C) 2016 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, or (at your option) any later version.
*/
#include <linux/security.h>
#include <linux/export.h>
#include <linux/lsm_hooks.h>
static enum lockdown_reason kernel_locked_down;
static char *lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
[LOCKDOWN_NONE] = "none",
[LOCKDOWN_MODULE_SIGNATURE] = "unsigned module loading",
[LOCKDOWN_DEV_MEM] = "/dev/mem,kmem,port",
[LOCKDOWN_KEXEC] = "kexec of unsigned images",
[LOCKDOWN_HIBERNATION] = "hibernation",
[LOCKDOWN_PCI_ACCESS] = "direct PCI access",
[LOCKDOWN_INTEGRITY_MAX] = "integrity",
[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
};
static enum lockdown_reason lockdown_levels[] = {LOCKDOWN_NONE,
LOCKDOWN_INTEGRITY_MAX,
LOCKDOWN_CONFIDENTIALITY_MAX};
/*
* Put the kernel into lock-down mode.
*/
static int lock_kernel_down(const char *where, enum lockdown_reason level)
{
if (kernel_locked_down >= level)
return -EPERM;
kernel_locked_down = level;
pr_notice("Kernel is locked down from %s; see man kernel_lockdown.7\n",
where);
return 0;
}
static int __init lockdown_param(char *level)
{
if (!level)
return -EINVAL;
if (strcmp(level, "integrity") == 0)
lock_kernel_down("command line", LOCKDOWN_INTEGRITY_MAX);
else if (strcmp(level, "confidentiality") == 0)
lock_kernel_down("command line", LOCKDOWN_CONFIDENTIALITY_MAX);
else
return -EINVAL;
return 0;
}
early_param("lockdown", lockdown_param);
/**
* lockdown_is_locked_down - Find out if the kernel is locked down
* @what: Tag to use in notice generated if lockdown is in effect
*/
static int lockdown_is_locked_down(enum lockdown_reason what)
{
if (kernel_locked_down >= what) {
if (lockdown_reasons[what])
pr_notice("Lockdown: %s is restricted; see man kernel_lockdown.7\n",
lockdown_reasons[what]);
return -EPERM;
}
return 0;
}
static struct security_hook_list lockdown_hooks[] __lsm_ro_after_init = {
LSM_HOOK_INIT(locked_down, lockdown_is_locked_down),
};
static int __init lockdown_lsm_init(void)
{
#if defined(CONFIG_LOCK_DOWN_KERNEL_FORCE_INTEGRITY)
lock_kernel_down("Kernel configuration", LOCKDOWN_INTEGRITY_MAX);
#elif defined(CONFIG_LOCK_DOWN_KERNEL_FORCE_CONFIDENTIALITY)
lock_kernel_down("Kernel configuration", LOCKDOWN_CONFIDENTIALITY_MAX);
#endif
security_add_hooks(lockdown_hooks, ARRAY_SIZE(lockdown_hooks),
"lockdown");
return 0;
}
static ssize_t lockdown_read(struct file *filp, char __user *buf, size_t count,
loff_t *ppos)
{
char temp[80];
int i, offset = 0;
for (i = 0; i < ARRAY_SIZE(lockdown_levels); i++) {
enum lockdown_reason level = lockdown_levels[i];
if (lockdown_reasons[level]) {
const char *label = lockdown_reasons[level];
if (kernel_locked_down == level)
offset += sprintf(temp+offset, "[%s] ", label);
else
offset += sprintf(temp+offset, "%s ", label);
}
}
/* Convert the last space to a newline if needed. */
if (offset > 0)
temp[offset-1] = '\n';
return simple_read_from_buffer(buf, count, ppos, temp, strlen(temp));
}
static ssize_t lockdown_write(struct file *file, const char __user *buf,
size_t n, loff_t *ppos)
{
char *state;
int i, len, err = -EINVAL;
state = memdup_user_nul(buf, n);
if (IS_ERR(state))
return PTR_ERR(state);
len = strlen(state);
if (len && state[len-1] == '\n') {
state[len-1] = '\0';
len--;
}
for (i = 0; i < ARRAY_SIZE(lockdown_levels); i++) {
enum lockdown_reason level = lockdown_levels[i];
const char *label = lockdown_reasons[level];
if (label && !strcmp(state, label))
err = lock_kernel_down("securityfs", level);
}
kfree(state);
return err ? err : n;
}
static const struct file_operations lockdown_ops = {
.read = lockdown_read,
.write = lockdown_write,
};
static int __init lockdown_secfs_init(void)
{
struct dentry *dentry;
dentry = securityfs_create_file("lockdown", 0600, NULL, NULL,
&lockdown_ops);
return PTR_ERR_OR_ZERO(dentry);
}
core_initcall(lockdown_secfs_init);
#ifdef CONFIG_SECURITY_LOCKDOWN_LSM_EARLY
DEFINE_EARLY_LSM(lockdown) = {
#else
DEFINE_LSM(lockdown) = {
#endif
.name = "lockdown",
.init = lockdown_lsm_init,
};
|
