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
237
238
239
240
241
242
243
244
245
246
247
248
|
// SPDX-License-Identifier: GPL-2.0+
/*
* Copyright (C) 2019 IBM Corporation <nayna@linux.ibm.com>
*
* This code exposes secure variables to user via sysfs
*/
#define pr_fmt(fmt) "secvar-sysfs: "fmt
#include <linux/slab.h>
#include <linux/compat.h>
#include <linux/string.h>
#include <linux/of.h>
#include <asm/secvar.h>
#define NAME_MAX_SIZE 1024
static struct kobject *secvar_kobj;
static struct kset *secvar_kset;
static ssize_t format_show(struct kobject *kobj, struct kobj_attribute *attr,
char *buf)
{
ssize_t rc = 0;
struct device_node *node;
const char *format;
node = of_find_compatible_node(NULL, NULL, "ibm,secvar-backend");
if (!of_device_is_available(node))
return -ENODEV;
rc = of_property_read_string(node, "format", &format);
if (rc)
return rc;
rc = sprintf(buf, "%s\n", format);
of_node_put(node);
return rc;
}
static ssize_t size_show(struct kobject *kobj, struct kobj_attribute *attr,
char *buf)
{
uint64_t dsize;
int rc;
rc = secvar_ops->get(kobj->name, strlen(kobj->name) + 1, NULL, &dsize);
if (rc) {
pr_err("Error retrieving %s variable size %d\n", kobj->name,
rc);
return rc;
}
return sprintf(buf, "%llu\n", dsize);
}
static ssize_t data_read(struct file *filep, struct kobject *kobj,
struct bin_attribute *attr, char *buf, loff_t off,
size_t count)
{
uint64_t dsize;
char *data;
int rc;
rc = secvar_ops->get(kobj->name, strlen(kobj->name) + 1, NULL, &dsize);
if (rc) {
pr_err("Error getting %s variable size %d\n", kobj->name, rc);
return rc;
}
pr_debug("dsize is %llu\n", dsize);
data = kzalloc(dsize, GFP_KERNEL);
if (!data)
return -ENOMEM;
rc = secvar_ops->get(kobj->name, strlen(kobj->name) + 1, data, &dsize);
if (rc) {
pr_err("Error getting %s variable %d\n", kobj->name, rc);
goto data_fail;
}
rc = memory_read_from_buffer(buf, count, &off, data, dsize);
data_fail:
kfree(data);
return rc;
}
static ssize_t update_write(struct file *filep, struct kobject *kobj,
struct bin_attribute *attr, char *buf, loff_t off,
size_t count)
{
int rc;
pr_debug("count is %ld\n", count);
rc = secvar_ops->set(kobj->name, strlen(kobj->name) + 1, buf, count);
if (rc) {
pr_err("Error setting the %s variable %d\n", kobj->name, rc);
return rc;
}
return count;
}
static struct kobj_attribute format_attr = __ATTR_RO(format);
static struct kobj_attribute size_attr = __ATTR_RO(size);
static struct bin_attribute data_attr = __BIN_ATTR_RO(data, 0);
static struct bin_attribute update_attr = __BIN_ATTR_WO(update, 0);
static struct bin_attribute *secvar_bin_attrs[] = {
&data_attr,
&update_attr,
NULL,
};
static struct attribute *secvar_attrs[] = {
&size_attr.attr,
NULL,
};
static const struct attribute_group secvar_attr_group = {
.attrs = secvar_attrs,
.bin_attrs = secvar_bin_attrs,
};
__ATTRIBUTE_GROUPS(secvar_attr);
static struct kobj_type secvar_ktype = {
.sysfs_ops = &kobj_sysfs_ops,
.default_groups = secvar_attr_groups,
};
static int update_kobj_size(void)
{
struct device_node *node;
u64 varsize;
int rc = 0;
node = of_find_compatible_node(NULL, NULL, "ibm,secvar-backend");
if (!of_device_is_available(node)) {
rc = -ENODEV;
goto out;
}
rc = of_property_read_u64(node, "max-var-size", &varsize);
if (rc)
goto out;
data_attr.size = varsize;
update_attr.size = varsize;
out:
of_node_put(node);
return rc;
}
static int secvar_sysfs_load(void)
{
char *name;
uint64_t namesize = 0;
struct kobject *kobj;
int rc;
name = kzalloc(NAME_MAX_SIZE, GFP_KERNEL);
if (!name)
return -ENOMEM;
do {
rc = secvar_ops->get_next(name, &namesize, NAME_MAX_SIZE);
if (rc) {
if (rc != -ENOENT)
pr_err("error getting secvar from firmware %d\n",
rc);
break;
}
kobj = kzalloc(sizeof(*kobj), GFP_KERNEL);
if (!kobj) {
rc = -ENOMEM;
break;
}
kobject_init(kobj, &secvar_ktype);
rc = kobject_add(kobj, &secvar_kset->kobj, "%s", name);
if (rc) {
pr_warn("kobject_add error %d for attribute: %s\n", rc,
name);
kobject_put(kobj);
kobj = NULL;
}
if (kobj)
kobject_uevent(kobj, KOBJ_ADD);
} while (!rc);
kfree(name);
return rc;
}
static int secvar_sysfs_init(void)
{
int rc;
if (!secvar_ops) {
pr_warn("secvar: failed to retrieve secvar operations.\n");
return -ENODEV;
}
secvar_kobj = kobject_create_and_add("secvar", firmware_kobj);
if (!secvar_kobj) {
pr_err("secvar: Failed to create firmware kobj\n");
return -ENOMEM;
}
rc = sysfs_create_file(secvar_kobj, &format_attr.attr);
if (rc) {
kobject_put(secvar_kobj);
return -ENOMEM;
}
secvar_kset = kset_create_and_add("vars", NULL, secvar_kobj);
if (!secvar_kset) {
pr_err("secvar: sysfs kobject registration failed.\n");
kobject_put(secvar_kobj);
return -ENOMEM;
}
rc = update_kobj_size();
if (rc) {
pr_err("Cannot read the size of the attribute\n");
return rc;
}
secvar_sysfs_load();
return 0;
}
late_initcall(secvar_sysfs_init);
|
