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
|
// SPDX-License-Identifier: GPL-2.0
#define pr_fmt(fmt) "ASYM-TPM: "fmt
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/export.h>
#include <linux/kernel.h>
#include <linux/seq_file.h>
#include <linux/scatterlist.h>
#include <linux/tpm.h>
#include <asm/unaligned.h>
#include <keys/asymmetric-subtype.h>
#include <crypto/asym_tpm_subtype.h>
/*
* Provide a part of a description of the key for /proc/keys.
*/
static void asym_tpm_describe(const struct key *asymmetric_key,
struct seq_file *m)
{
struct tpm_key *tk = asymmetric_key->payload.data[asym_crypto];
if (!tk)
return;
seq_printf(m, "TPM1.2/Blob");
}
static void asym_tpm_destroy(void *payload0, void *payload3)
{
struct tpm_key *tk = payload0;
if (!tk)
return;
kfree(tk->blob);
tk->blob_len = 0;
kfree(tk);
}
/*
* Parse enough information out of TPM_KEY structure:
* TPM_STRUCT_VER -> 4 bytes
* TPM_KEY_USAGE -> 2 bytes
* TPM_KEY_FLAGS -> 4 bytes
* TPM_AUTH_DATA_USAGE -> 1 byte
* TPM_KEY_PARMS -> variable
* UINT32 PCRInfoSize -> 4 bytes
* BYTE* -> PCRInfoSize bytes
* TPM_STORE_PUBKEY
* UINT32 encDataSize;
* BYTE* -> encDataSize;
*
* TPM_KEY_PARMS:
* TPM_ALGORITHM_ID -> 4 bytes
* TPM_ENC_SCHEME -> 2 bytes
* TPM_SIG_SCHEME -> 2 bytes
* UINT32 parmSize -> 4 bytes
* BYTE* -> variable
*/
static int extract_key_parameters(struct tpm_key *tk)
{
const void *cur = tk->blob;
uint32_t len = tk->blob_len;
const void *pub_key;
uint32_t sz;
uint32_t key_len;
if (len < 11)
return -EBADMSG;
/* Ensure this is a legacy key */
if (get_unaligned_be16(cur + 4) != 0x0015)
return -EBADMSG;
/* Skip to TPM_KEY_PARMS */
cur += 11;
len -= 11;
if (len < 12)
return -EBADMSG;
/* Make sure this is an RSA key */
if (get_unaligned_be32(cur) != 0x00000001)
return -EBADMSG;
/* Make sure this is TPM_ES_RSAESPKCSv15 encoding scheme */
if (get_unaligned_be16(cur + 4) != 0x0002)
return -EBADMSG;
/* Make sure this is TPM_SS_RSASSAPKCS1v15_DER signature scheme */
if (get_unaligned_be16(cur + 6) != 0x0003)
return -EBADMSG;
sz = get_unaligned_be32(cur + 8);
if (len < sz + 12)
return -EBADMSG;
/* Move to TPM_RSA_KEY_PARMS */
len -= 12;
cur += 12;
/* Grab the RSA key length */
key_len = get_unaligned_be32(cur);
switch (key_len) {
case 512:
case 1024:
case 1536:
case 2048:
break;
default:
return -EINVAL;
}
/* Move just past TPM_KEY_PARMS */
cur += sz;
len -= sz;
if (len < 4)
return -EBADMSG;
sz = get_unaligned_be32(cur);
if (len < 4 + sz)
return -EBADMSG;
/* Move to TPM_STORE_PUBKEY */
cur += 4 + sz;
len -= 4 + sz;
/* Grab the size of the public key, it should jive with the key size */
sz = get_unaligned_be32(cur);
if (sz > 256)
return -EINVAL;
pub_key = cur + 4;
tk->key_len = key_len;
tk->pub_key = pub_key;
tk->pub_key_len = sz;
return 0;
}
/* Given the blob, parse it and load it into the TPM */
struct tpm_key *tpm_key_create(const void *blob, uint32_t blob_len)
{
int r;
struct tpm_key *tk;
r = tpm_is_tpm2(NULL);
if (r < 0)
goto error;
/* We don't support TPM2 yet */
if (r > 0) {
r = -ENODEV;
goto error;
}
r = -ENOMEM;
tk = kzalloc(sizeof(struct tpm_key), GFP_KERNEL);
if (!tk)
goto error;
tk->blob = kmemdup(blob, blob_len, GFP_KERNEL);
if (!tk->blob)
goto error_memdup;
tk->blob_len = blob_len;
r = extract_key_parameters(tk);
if (r < 0)
goto error_extract;
return tk;
error_extract:
kfree(tk->blob);
tk->blob_len = 0;
error_memdup:
kfree(tk);
error:
return ERR_PTR(r);
}
EXPORT_SYMBOL_GPL(tpm_key_create);
/*
* TPM-based asymmetric key subtype
*/
struct asymmetric_key_subtype asym_tpm_subtype = {
.owner = THIS_MODULE,
.name = "asym_tpm",
.name_len = sizeof("asym_tpm") - 1,
.describe = asym_tpm_describe,
.destroy = asym_tpm_destroy,
};
EXPORT_SYMBOL_GPL(asym_tpm_subtype);
MODULE_DESCRIPTION("TPM based asymmetric key subtype");
MODULE_AUTHOR("Intel Corporation");
MODULE_LICENSE("GPL v2");
|
