This source file includes following definitions.
- lock_kernel_down
- lockdown_param
- lockdown_is_locked_down
- lockdown_lsm_init
- lockdown_read
- lockdown_write
- lockdown_secfs_init
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13 #include <linux/security.h>
14 #include <linux/export.h>
15 #include <linux/lsm_hooks.h>
16
17 static enum lockdown_reason kernel_locked_down;
18
19 static const char *const lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
20 [LOCKDOWN_NONE] = "none",
21 [LOCKDOWN_MODULE_SIGNATURE] = "unsigned module loading",
22 [LOCKDOWN_DEV_MEM] = "/dev/mem,kmem,port",
23 [LOCKDOWN_EFI_TEST] = "/dev/efi_test access",
24 [LOCKDOWN_KEXEC] = "kexec of unsigned images",
25 [LOCKDOWN_HIBERNATION] = "hibernation",
26 [LOCKDOWN_PCI_ACCESS] = "direct PCI access",
27 [LOCKDOWN_IOPORT] = "raw io port access",
28 [LOCKDOWN_MSR] = "raw MSR access",
29 [LOCKDOWN_ACPI_TABLES] = "modifying ACPI tables",
30 [LOCKDOWN_PCMCIA_CIS] = "direct PCMCIA CIS storage",
31 [LOCKDOWN_TIOCSSERIAL] = "reconfiguration of serial port IO",
32 [LOCKDOWN_MODULE_PARAMETERS] = "unsafe module parameters",
33 [LOCKDOWN_MMIOTRACE] = "unsafe mmio",
34 [LOCKDOWN_DEBUGFS] = "debugfs access",
35 [LOCKDOWN_XMON_WR] = "xmon write access",
36 [LOCKDOWN_INTEGRITY_MAX] = "integrity",
37 [LOCKDOWN_KCORE] = "/proc/kcore access",
38 [LOCKDOWN_KPROBES] = "use of kprobes",
39 [LOCKDOWN_BPF_READ] = "use of bpf to read kernel RAM",
40 [LOCKDOWN_PERF] = "unsafe use of perf",
41 [LOCKDOWN_TRACEFS] = "use of tracefs",
42 [LOCKDOWN_XMON_RW] = "xmon read and write access",
43 [LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
44 };
45
46 static const enum lockdown_reason lockdown_levels[] = {LOCKDOWN_NONE,
47 LOCKDOWN_INTEGRITY_MAX,
48 LOCKDOWN_CONFIDENTIALITY_MAX};
49
50
51
52
53 static int lock_kernel_down(const char *where, enum lockdown_reason level)
54 {
55 if (kernel_locked_down >= level)
56 return -EPERM;
57
58 kernel_locked_down = level;
59 pr_notice("Kernel is locked down from %s; see man kernel_lockdown.7\n",
60 where);
61 return 0;
62 }
63
64 static int __init lockdown_param(char *level)
65 {
66 if (!level)
67 return -EINVAL;
68
69 if (strcmp(level, "integrity") == 0)
70 lock_kernel_down("command line", LOCKDOWN_INTEGRITY_MAX);
71 else if (strcmp(level, "confidentiality") == 0)
72 lock_kernel_down("command line", LOCKDOWN_CONFIDENTIALITY_MAX);
73 else
74 return -EINVAL;
75
76 return 0;
77 }
78
79 early_param("lockdown", lockdown_param);
80
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83
84
85 static int lockdown_is_locked_down(enum lockdown_reason what)
86 {
87 if (WARN(what >= LOCKDOWN_CONFIDENTIALITY_MAX,
88 "Invalid lockdown reason"))
89 return -EPERM;
90
91 if (kernel_locked_down >= what) {
92 if (lockdown_reasons[what])
93 pr_notice("Lockdown: %s: %s is restricted; see man kernel_lockdown.7\n",
94 current->comm, lockdown_reasons[what]);
95 return -EPERM;
96 }
97
98 return 0;
99 }
100
101 static struct security_hook_list lockdown_hooks[] __lsm_ro_after_init = {
102 LSM_HOOK_INIT(locked_down, lockdown_is_locked_down),
103 };
104
105 static int __init lockdown_lsm_init(void)
106 {
107 #if defined(CONFIG_LOCK_DOWN_KERNEL_FORCE_INTEGRITY)
108 lock_kernel_down("Kernel configuration", LOCKDOWN_INTEGRITY_MAX);
109 #elif defined(CONFIG_LOCK_DOWN_KERNEL_FORCE_CONFIDENTIALITY)
110 lock_kernel_down("Kernel configuration", LOCKDOWN_CONFIDENTIALITY_MAX);
111 #endif
112 security_add_hooks(lockdown_hooks, ARRAY_SIZE(lockdown_hooks),
113 "lockdown");
114 return 0;
115 }
116
117 static ssize_t lockdown_read(struct file *filp, char __user *buf, size_t count,
118 loff_t *ppos)
119 {
120 char temp[80];
121 int i, offset = 0;
122
123 for (i = 0; i < ARRAY_SIZE(lockdown_levels); i++) {
124 enum lockdown_reason level = lockdown_levels[i];
125
126 if (lockdown_reasons[level]) {
127 const char *label = lockdown_reasons[level];
128
129 if (kernel_locked_down == level)
130 offset += sprintf(temp+offset, "[%s] ", label);
131 else
132 offset += sprintf(temp+offset, "%s ", label);
133 }
134 }
135
136
137 if (offset > 0)
138 temp[offset-1] = '\n';
139
140 return simple_read_from_buffer(buf, count, ppos, temp, strlen(temp));
141 }
142
143 static ssize_t lockdown_write(struct file *file, const char __user *buf,
144 size_t n, loff_t *ppos)
145 {
146 char *state;
147 int i, len, err = -EINVAL;
148
149 state = memdup_user_nul(buf, n);
150 if (IS_ERR(state))
151 return PTR_ERR(state);
152
153 len = strlen(state);
154 if (len && state[len-1] == '\n') {
155 state[len-1] = '\0';
156 len--;
157 }
158
159 for (i = 0; i < ARRAY_SIZE(lockdown_levels); i++) {
160 enum lockdown_reason level = lockdown_levels[i];
161 const char *label = lockdown_reasons[level];
162
163 if (label && !strcmp(state, label))
164 err = lock_kernel_down("securityfs", level);
165 }
166
167 kfree(state);
168 return err ? err : n;
169 }
170
171 static const struct file_operations lockdown_ops = {
172 .read = lockdown_read,
173 .write = lockdown_write,
174 };
175
176 static int __init lockdown_secfs_init(void)
177 {
178 struct dentry *dentry;
179
180 dentry = securityfs_create_file("lockdown", 0600, NULL, NULL,
181 &lockdown_ops);
182 return PTR_ERR_OR_ZERO(dentry);
183 }
184
185 core_initcall(lockdown_secfs_init);
186
187 #ifdef CONFIG_SECURITY_LOCKDOWN_LSM_EARLY
188 DEFINE_EARLY_LSM(lockdown) = {
189 #else
190 DEFINE_LSM(lockdown) = {
191 #endif
192 .name = "lockdown",
193 .init = lockdown_lsm_init,
194 };