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
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
|
/* SPDX-License-Identifier: LGPL-2.1-or-later */
#include "ask-password-api.h"
#include "cryptsetup-fido2.h"
#include "env-util.h"
#include "fileio.h"
#include "hexdecoct.h"
#include "json.h"
#include "libfido2-util.h"
#include "parse-util.h"
#include "random-util.h"
#include "strv.h"
int acquire_fido2_key(
const char *volume_name,
const char *friendly_name,
const char *device,
const char *rp_id,
const void *cid,
size_t cid_size,
const char *key_file,
size_t key_file_size,
uint64_t key_file_offset,
const void *key_data,
size_t key_data_size,
usec_t until,
bool headless,
Fido2EnrollFlags required,
void **ret_decrypted_key,
size_t *ret_decrypted_key_size,
AskPasswordFlags ask_password_flags) {
_cleanup_(erase_and_freep) char *envpw = NULL;
_cleanup_strv_free_erase_ char **pins = NULL;
_cleanup_free_ void *loaded_salt = NULL;
bool device_exists = false;
const char *salt;
size_t salt_size;
int r;
if ((required & (FIDO2ENROLL_PIN | FIDO2ENROLL_UP | FIDO2ENROLL_UV)) && headless)
return log_error_errno(SYNTHETIC_ERRNO(ENOPKG),
"Local verification is required to unlock this volume, but the 'headless' parameter was set.");
ask_password_flags |= ASK_PASSWORD_PUSH_CACHE | ASK_PASSWORD_ACCEPT_CACHED;
assert(cid);
assert(key_file || key_data);
if (key_data) {
salt = key_data;
salt_size = key_data_size;
} else {
_cleanup_free_ char *bindname = NULL;
/* If we read the salt via AF_UNIX, make this client recognizable */
if (asprintf(&bindname, "@%" PRIx64"/cryptsetup-fido2/%s", random_u64(), volume_name) < 0)
return log_oom();
r = read_full_file_full(
AT_FDCWD, key_file,
key_file_offset == 0 ? UINT64_MAX : key_file_offset,
key_file_size == 0 ? SIZE_MAX : key_file_size,
READ_FULL_FILE_CONNECT_SOCKET,
bindname,
(char**) &loaded_salt, &salt_size);
if (r < 0)
return r;
salt = loaded_salt;
}
r = getenv_steal_erase("PIN", &envpw);
if (r < 0)
return log_error_errno(r, "Failed to acquire password from environment: %m");
if (r > 0) {
pins = strv_new(envpw);
if (!pins)
return log_oom();
}
for (;;) {
if (!device_exists) {
/* Before we inquire for the PIN we'll need, if we never talked to the device, check
* if the device actually is plugged in. Otherwise we'll ask for the PIN already when
* the device is not plugged in, which is confusing. */
r = fido2_have_device(device);
if (r < 0)
return r;
if (r == 0) /* no device found, return EAGAIN so that caller will wait/watch udev */
return -EAGAIN;
device_exists = true; /* now we know for sure, a device exists, no need to ask again */
}
/* Always make an attempt before asking for PIN.
* fido2_use_hmac_hash() will perform a pre-flight check for whether the credential for
* can be found on one of the connected devices. This way, we can avoid prompting the user
* for a PIN when we are sure that no device can be used. */
r = fido2_use_hmac_hash(
device,
rp_id ?: "io.systemd.cryptsetup",
salt, salt_size,
cid, cid_size,
pins,
required,
ret_decrypted_key,
ret_decrypted_key_size);
if (!IN_SET(r,
-ENOANO, /* needs pin */
-ENOLCK)) /* pin incorrect */
return r;
device_exists = true; /* that a PIN is needed/wasn't correct means that we managed to
* talk to a device */
if (headless)
return log_error_errno(SYNTHETIC_ERRNO(ENOPKG), "PIN querying disabled via 'headless' option. Use the '$PIN' environment variable.");
pins = strv_free_erase(pins);
r = ask_password_auto("Please enter security token PIN:", "drive-harddisk", NULL, "fido2-pin", "cryptsetup.fido2-pin", until, ask_password_flags, &pins);
if (r < 0)
return log_error_errno(r, "Failed to ask for user password: %m");
ask_password_flags &= ~ASK_PASSWORD_ACCEPT_CACHED;
}
}
int acquire_fido2_key_auto(
struct crypt_device *cd,
const char *name,
const char *friendly_name,
const char *fido2_device,
const char *key_file,
size_t key_file_size,
uint64_t key_file_offset,
usec_t until,
bool headless,
void **ret_decrypted_key,
size_t *ret_decrypted_key_size,
AskPasswordFlags ask_password_flags) {
_cleanup_free_ void *cid = NULL;
size_t cid_size = 0;
int r, ret = -ENOENT;
Fido2EnrollFlags required = 0;
assert(cd);
assert(name);
assert(ret_decrypted_key);
assert(ret_decrypted_key_size);
/* Loads FIDO2 metadata from LUKS2 JSON token headers. */
for (int token = 0; token < sym_crypt_token_max(CRYPT_LUKS2); token ++) {
_cleanup_(json_variant_unrefp) JsonVariant *v = NULL;
JsonVariant *w;
_cleanup_free_ void *salt = NULL;
_cleanup_free_ char *rp = NULL;
size_t salt_size = 0;
int ks;
r = cryptsetup_get_token_as_json(cd, token, "systemd-fido2", &v);
if (IN_SET(r, -ENOENT, -EINVAL, -EMEDIUMTYPE))
continue;
if (r < 0)
return log_error_errno(r, "Failed to read JSON token data off disk: %m");
ks = cryptsetup_get_keyslot_from_token(v);
if (ks < 0) {
/* Handle parsing errors of the keyslots field gracefully, since it's not 'owned' by
* us, but by the LUKS2 spec */
log_warning_errno(ks, "Failed to extract keyslot index from FIDO2 JSON data token %i, skipping: %m", token);
continue;
}
w = json_variant_by_key(v, "fido2-credential");
if (!w || !json_variant_is_string(w))
return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
"FIDO2 token data lacks 'fido2-credential' field.");
r = unbase64mem(json_variant_string(w), SIZE_MAX, &cid, &cid_size);
if (r < 0)
return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
"Invalid base64 data in 'fido2-credential' field.");
w = json_variant_by_key(v, "fido2-salt");
if (!w || !json_variant_is_string(w))
return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
"FIDO2 token data lacks 'fido2-salt' field.");
assert(!salt);
assert(salt_size == 0);
r = unbase64mem(json_variant_string(w), SIZE_MAX, &salt, &salt_size);
if (r < 0)
return log_error_errno(r, "Failed to decode base64 encoded salt.");
w = json_variant_by_key(v, "fido2-rp");
if (w) {
/* The "rp" field is optional. */
if (!json_variant_is_string(w))
return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
"FIDO2 token data's 'fido2-rp' field is not a string.");
assert(!rp);
rp = strdup(json_variant_string(w));
if (!rp)
return log_oom();
}
w = json_variant_by_key(v, "fido2-clientPin-required");
if (w) {
/* The "fido2-clientPin-required" field is optional. */
if (!json_variant_is_boolean(w))
return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
"FIDO2 token data's 'fido2-clientPin-required' field is not a boolean.");
SET_FLAG(required, FIDO2ENROLL_PIN, json_variant_boolean(w));
} else
required |= FIDO2ENROLL_PIN_IF_NEEDED; /* compat with 248, where the field was unset */
w = json_variant_by_key(v, "fido2-up-required");
if (w) {
/* The "fido2-up-required" field is optional. */
if (!json_variant_is_boolean(w))
return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
"FIDO2 token data's 'fido2-up-required' field is not a boolean.");
SET_FLAG(required, FIDO2ENROLL_UP, json_variant_boolean(w));
} else
required |= FIDO2ENROLL_UP_IF_NEEDED; /* compat with 248 */
w = json_variant_by_key(v, "fido2-uv-required");
if (w) {
/* The "fido2-uv-required" field is optional. */
if (!json_variant_is_boolean(w))
return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
"FIDO2 token data's 'fido2-uv-required' field is not a boolean.");
SET_FLAG(required, FIDO2ENROLL_UV, json_variant_boolean(w));
} else
required |= FIDO2ENROLL_UV_OMIT; /* compat with 248 */
ret = acquire_fido2_key(
name,
friendly_name,
fido2_device,
rp,
cid, cid_size,
key_file, key_file_size, key_file_offset,
salt, salt_size,
until,
headless,
required,
ret_decrypted_key, ret_decrypted_key_size,
ask_password_flags);
if (ret == 0)
break;
}
if (!cid)
return log_error_errno(SYNTHETIC_ERRNO(ENXIO),
"No valid FIDO2 token data found.");
if (ret == -EAGAIN) /* fido2 device does not exist, or UV is blocked; caller will prompt for retry */
return log_debug_errno(ret, "FIDO2 token does not exist, or UV is blocked.");
if (ret < 0)
return log_error_errno(ret, "Failed to unlock LUKS volume with FIDO2 token: %m");
log_info("Unlocked volume via automatically discovered security FIDO2 token.");
return ret;
}
|
