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Commit | Line | Data |
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5e521624 LP |
1 | /* SPDX-License-Identifier: LGPL-2.1-or-later */ |
2 | ||
3 | #include "alloc-util.h" | |
6c7a1681 | 4 | #include "ask-password-api.h" |
5e521624 | 5 | #include "cryptenroll-tpm2.h" |
6c7a1681 | 6 | #include "env-util.h" |
f0f4fcae | 7 | #include "fileio.h" |
5e521624 LP |
8 | #include "hexdecoct.h" |
9 | #include "json.h" | |
10 | #include "memory-util.h" | |
aae6eb96 WR |
11 | #include "random-util.h" |
12 | #include "sha256.h" | |
5e521624 LP |
13 | #include "tpm2-util.h" |
14 | ||
15 | static int search_policy_hash( | |
16 | struct crypt_device *cd, | |
17 | const void *hash, | |
18 | size_t hash_size) { | |
19 | ||
20 | int r; | |
21 | ||
22 | assert(cd); | |
23 | assert(hash || hash_size == 0); | |
24 | ||
25 | if (hash_size == 0) | |
26 | return 0; | |
27 | ||
b3a9d980 | 28 | for (int token = 0; token < sym_crypt_token_max(CRYPT_LUKS2); token++) { |
5e521624 LP |
29 | _cleanup_(json_variant_unrefp) JsonVariant *v = NULL; |
30 | _cleanup_free_ void *thash = NULL; | |
31 | size_t thash_size = 0; | |
32 | int keyslot; | |
33 | JsonVariant *w; | |
34 | ||
35 | r = cryptsetup_get_token_as_json(cd, token, "systemd-tpm2", &v); | |
36 | if (IN_SET(r, -ENOENT, -EINVAL, -EMEDIUMTYPE)) | |
37 | continue; | |
38 | if (r < 0) | |
39 | return log_error_errno(r, "Failed to read JSON token data off disk: %m"); | |
40 | ||
41 | keyslot = cryptsetup_get_keyslot_from_token(v); | |
1641c2b1 LP |
42 | if (keyslot < 0) { |
43 | /* Handle parsing errors of the keyslots field gracefully, since it's not 'owned' by | |
44 | * us, but by the LUKS2 spec */ | |
45 | log_warning_errno(keyslot, "Failed to determine keyslot of JSON token %i, skipping: %m", token); | |
46 | continue; | |
47 | } | |
5e521624 LP |
48 | |
49 | w = json_variant_by_key(v, "tpm2-policy-hash"); | |
50 | if (!w || !json_variant_is_string(w)) | |
51 | return log_error_errno(SYNTHETIC_ERRNO(EINVAL), | |
52 | "TPM2 token data lacks 'tpm2-policy-hash' field."); | |
53 | ||
bdd2036e | 54 | r = unhexmem(json_variant_string(w), &thash, &thash_size); |
5e521624 LP |
55 | if (r < 0) |
56 | return log_error_errno(SYNTHETIC_ERRNO(EINVAL), | |
57 | "Invalid base64 data in 'tpm2-policy-hash' field."); | |
58 | ||
59 | if (memcmp_nn(hash, hash_size, thash, thash_size) == 0) | |
60 | return keyslot; /* Found entry with same hash. */ | |
61 | } | |
62 | ||
63 | return -ENOENT; /* Not found */ | |
64 | } | |
65 | ||
6c7a1681 | 66 | static int get_pin(char **ret_pin_str, TPM2Flags *ret_flags) { |
a3b46c6b | 67 | _cleanup_(erase_and_freep) char *pin_str = NULL; |
6c7a1681 | 68 | TPM2Flags flags = 0; |
a3b46c6b | 69 | int r; |
6c7a1681 GG |
70 | |
71 | assert(ret_pin_str); | |
72 | assert(ret_flags); | |
73 | ||
74 | r = getenv_steal_erase("NEWPIN", &pin_str); | |
75 | if (r < 0) | |
76 | return log_error_errno(r, "Failed to acquire PIN from environment: %m"); | |
77 | if (r > 0) | |
78 | flags |= TPM2_FLAGS_USE_PIN; | |
79 | else { | |
80 | for (size_t i = 5;; i--) { | |
81 | _cleanup_strv_free_erase_ char **pin = NULL, **pin2 = NULL; | |
82 | ||
83 | if (i <= 0) | |
84 | return log_error_errno( | |
85 | SYNTHETIC_ERRNO(ENOKEY), "Too many attempts, giving up."); | |
86 | ||
87 | pin = strv_free_erase(pin); | |
88 | r = ask_password_auto( | |
89 | "Please enter TPM2 PIN:", | |
90 | "drive-harddisk", | |
91 | NULL, | |
92 | "tpm2-pin", | |
93 | "cryptenroll.tpm2-pin", | |
94 | USEC_INFINITY, | |
95 | 0, | |
96 | &pin); | |
97 | if (r < 0) | |
98 | return log_error_errno(r, "Failed to ask for user pin: %m"); | |
99 | assert(strv_length(pin) == 1); | |
100 | ||
101 | r = ask_password_auto( | |
102 | "Please enter TPM2 PIN (repeat):", | |
103 | "drive-harddisk", | |
104 | NULL, | |
105 | "tpm2-pin", | |
106 | "cryptenroll.tpm2-pin", | |
107 | USEC_INFINITY, | |
108 | 0, | |
109 | &pin2); | |
110 | if (r < 0) | |
111 | return log_error_errno(r, "Failed to ask for user pin: %m"); | |
112 | assert(strv_length(pin) == 1); | |
113 | ||
114 | if (strv_equal(pin, pin2)) { | |
115 | pin_str = strdup(*pin); | |
116 | if (!pin_str) | |
117 | return log_oom(); | |
118 | flags |= TPM2_FLAGS_USE_PIN; | |
119 | break; | |
120 | } | |
121 | ||
122 | log_error("PINs didn't match, please try again!"); | |
123 | } | |
124 | } | |
125 | ||
126 | *ret_flags = flags; | |
127 | *ret_pin_str = TAKE_PTR(pin_str); | |
128 | ||
129 | return 0; | |
130 | } | |
131 | ||
5e521624 LP |
132 | int enroll_tpm2(struct crypt_device *cd, |
133 | const void *volume_key, | |
134 | size_t volume_key_size, | |
135 | const char *device, | |
382bfd90 | 136 | uint32_t seal_key_handle, |
c3a2a681 | 137 | const char *device_key, |
9e437994 DS |
138 | Tpm2PCRValue *hash_pcr_values, |
139 | size_t n_hash_pcr_values, | |
f0f4fcae LP |
140 | const char *pubkey_path, |
141 | uint32_t pubkey_pcr_mask, | |
142 | const char *signature_path, | |
404aea78 LP |
143 | bool use_pin, |
144 | const char *pcrlock_path) { | |
5e521624 | 145 | |
f0f4fcae | 146 | _cleanup_(json_variant_unrefp) JsonVariant *v = NULL, *signature_json = NULL; |
5e521624 | 147 | _cleanup_(erase_and_freep) char *base64_encoded = NULL; |
8d042bc4 LP |
148 | _cleanup_(iovec_done) struct iovec srk = {}, blob = {}, pubkey = {}; |
149 | _cleanup_(iovec_done_erase) struct iovec secret = {}; | |
5e521624 | 150 | const char *node; |
6c7a1681 | 151 | _cleanup_(erase_and_freep) char *pin_str = NULL; |
5e476b85 | 152 | ssize_t base64_encoded_size; |
5e521624 | 153 | int r, keyslot; |
6c7a1681 | 154 | TPM2Flags flags = 0; |
aae6eb96 WR |
155 | uint8_t binary_salt[SHA256_DIGEST_SIZE] = {}; |
156 | /* | |
157 | * erase the salt, we'd rather attempt to not have this in a coredump | |
158 | * as an attacker would have all the parameters but pin used to create | |
159 | * the session key. This problem goes away when we move to a trusted | |
160 | * primary key, aka the SRK. | |
161 | */ | |
162 | CLEANUP_ERASE(binary_salt); | |
5e521624 LP |
163 | |
164 | assert(cd); | |
165 | assert(volume_key); | |
166 | assert(volume_key_size > 0); | |
cc1a78d5 | 167 | assert(tpm2_pcr_values_valid(hash_pcr_values, n_hash_pcr_values)); |
f0f4fcae | 168 | assert(TPM2_PCR_MASK_VALID(pubkey_pcr_mask)); |
5e521624 LP |
169 | |
170 | assert_se(node = crypt_get_device_name(cd)); | |
171 | ||
6c7a1681 GG |
172 | if (use_pin) { |
173 | r = get_pin(&pin_str, &flags); | |
174 | if (r < 0) | |
175 | return r; | |
aae6eb96 WR |
176 | |
177 | r = crypto_random_bytes(binary_salt, sizeof(binary_salt)); | |
178 | if (r < 0) | |
179 | return log_error_errno(r, "Failed to acquire random salt: %m"); | |
180 | ||
181 | uint8_t salted_pin[SHA256_DIGEST_SIZE] = {}; | |
182 | CLEANUP_ERASE(salted_pin); | |
183 | r = tpm2_util_pbkdf2_hmac_sha256(pin_str, strlen(pin_str), binary_salt, sizeof(binary_salt), salted_pin); | |
184 | if (r < 0) | |
185 | return log_error_errno(r, "Failed to perform PBKDF2: %m"); | |
186 | ||
187 | pin_str = erase_and_free(pin_str); | |
188 | /* re-stringify pin_str */ | |
189 | base64_encoded_size = base64mem(salted_pin, sizeof(salted_pin), &pin_str); | |
190 | if (base64_encoded_size < 0) | |
191 | return log_error_errno(base64_encoded_size, "Failed to base64 encode salted pin: %m"); | |
6c7a1681 GG |
192 | } |
193 | ||
a4e9f3d3 | 194 | TPM2B_PUBLIC public = {}; |
8d042bc4 | 195 | r = tpm2_load_pcr_public_key(pubkey_path, &pubkey.iov_base, &pubkey.iov_len); |
f0f4fcae LP |
196 | if (r < 0) { |
197 | if (pubkey_path || signature_path || r != -ENOENT) | |
cb7aabf1 | 198 | return log_error_errno(r, "Failed to read TPM PCR public key: %m"); |
f0f4fcae LP |
199 | |
200 | log_debug_errno(r, "Failed to read TPM2 PCR public key, proceeding without: %m"); | |
201 | pubkey_pcr_mask = 0; | |
a4e9f3d3 | 202 | } else { |
8d042bc4 | 203 | r = tpm2_tpm2b_public_from_pem(pubkey.iov_base, pubkey.iov_len, &public); |
645063d1 | 204 | if (r < 0) |
a4e9f3d3 LP |
205 | return log_error_errno(r, "Could not convert public key to TPM2B_PUBLIC: %m"); |
206 | ||
207 | if (signature_path) { | |
208 | /* Also try to load the signature JSON object, to verify that our enrollment will work. | |
209 | * This is optional however, skip it if it's not explicitly provided. */ | |
210 | ||
211 | r = tpm2_load_pcr_signature(signature_path, &signature_json); | |
212 | if (r < 0) | |
213 | return log_debug_errno(r, "Failed to read TPM PCR signature: %m"); | |
214 | } | |
f0f4fcae LP |
215 | } |
216 | ||
c3a2a681 DS |
217 | bool any_pcr_value_specified = tpm2_pcr_values_has_any_values(hash_pcr_values, n_hash_pcr_values); |
218 | ||
404aea78 LP |
219 | _cleanup_(tpm2_pcrlock_policy_done) Tpm2PCRLockPolicy pcrlock_policy = {}; |
220 | if (pcrlock_path) { | |
221 | r = tpm2_pcrlock_policy_load(pcrlock_path, &pcrlock_policy); | |
222 | if (r < 0) | |
223 | return r; | |
224 | ||
c3a2a681 | 225 | any_pcr_value_specified = true; |
404aea78 LP |
226 | flags |= TPM2_FLAGS_USE_PCRLOCK; |
227 | } | |
228 | ||
9e437994 | 229 | _cleanup_(tpm2_context_unrefp) Tpm2Context *tpm2_context = NULL; |
c3a2a681 DS |
230 | TPM2B_PUBLIC device_key_public = {}; |
231 | if (device_key) { | |
a8d8d34b | 232 | r = tpm2_load_public_key_file(device_key, &device_key_public); |
c3a2a681 | 233 | if (r < 0) |
a8d8d34b | 234 | return r; |
c3a2a681 DS |
235 | |
236 | if (!tpm2_pcr_values_has_all_values(hash_pcr_values, n_hash_pcr_values)) | |
237 | return log_error_errno(SYNTHETIC_ERRNO(EINVAL), | |
238 | "Must provide all PCR values when using TPM2 device key."); | |
239 | } else { | |
240 | r = tpm2_context_new(device, &tpm2_context); | |
241 | if (r < 0) | |
242 | return log_error_errno(r, "Failed to create TPM2 context: %m"); | |
243 | ||
244 | if (!tpm2_pcr_values_has_all_values(hash_pcr_values, n_hash_pcr_values)) { | |
245 | r = tpm2_pcr_read_missing_values(tpm2_context, hash_pcr_values, n_hash_pcr_values); | |
246 | if (r < 0) | |
247 | return log_error_errno(r, "Could not read pcr values: %m"); | |
248 | } | |
249 | } | |
9e437994 DS |
250 | |
251 | uint16_t hash_pcr_bank = 0; | |
252 | uint32_t hash_pcr_mask = 0; | |
253 | if (n_hash_pcr_values > 0) { | |
254 | size_t hash_count; | |
255 | r = tpm2_pcr_values_hash_count(hash_pcr_values, n_hash_pcr_values, &hash_count); | |
256 | if (r < 0) | |
257 | return log_error_errno(r, "Could not get hash count: %m"); | |
258 | ||
259 | if (hash_count > 1) | |
260 | return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Multiple PCR banks selected."); | |
261 | ||
262 | hash_pcr_bank = hash_pcr_values[0].hash; | |
263 | r = tpm2_pcr_values_to_mask(hash_pcr_values, n_hash_pcr_values, hash_pcr_bank, &hash_pcr_mask); | |
264 | if (r < 0) | |
265 | return log_error_errno(r, "Could not get hash mask: %m"); | |
266 | } | |
267 | ||
9e437994 DS |
268 | TPM2B_DIGEST policy = TPM2B_DIGEST_MAKE(NULL, TPM2_SHA256_DIGEST_SIZE); |
269 | r = tpm2_calculate_sealing_policy( | |
270 | hash_pcr_values, | |
271 | n_hash_pcr_values, | |
8d042bc4 | 272 | iovec_is_set(&pubkey) ? &public : NULL, |
9e437994 | 273 | use_pin, |
404aea78 | 274 | pcrlock_path ? &pcrlock_policy : NULL, |
9e437994 DS |
275 | &policy); |
276 | if (r < 0) | |
277 | return r; | |
278 | ||
c3a2a681 DS |
279 | if (device_key) |
280 | r = tpm2_calculate_seal( | |
281 | seal_key_handle, | |
282 | &device_key_public, | |
283 | /* attributes= */ NULL, | |
8d042bc4 | 284 | /* secret= */ NULL, |
c3a2a681 DS |
285 | &policy, |
286 | pin_str, | |
8d042bc4 LP |
287 | &secret, |
288 | &blob, | |
289 | &srk); | |
c3a2a681 DS |
290 | else |
291 | r = tpm2_seal(tpm2_context, | |
292 | seal_key_handle, | |
293 | &policy, | |
294 | pin_str, | |
8d042bc4 LP |
295 | &secret, |
296 | &blob, | |
c3a2a681 | 297 | /* ret_primary_alg= */ NULL, |
8d042bc4 | 298 | &srk); |
5e521624 | 299 | if (r < 0) |
f9a0ee75 | 300 | return log_error_errno(r, "Failed to seal to TPM2: %m"); |
5e521624 LP |
301 | |
302 | /* Let's see if we already have this specific PCR policy hash enrolled, if so, exit early. */ | |
9e437994 | 303 | r = search_policy_hash(cd, policy.buffer, policy.size); |
5e521624 LP |
304 | if (r == -ENOENT) |
305 | log_debug_errno(r, "PCR policy hash not yet enrolled, enrolling now."); | |
306 | else if (r < 0) | |
307 | return r; | |
308 | else { | |
309 | log_info("This PCR set is already enrolled, executing no operation."); | |
310 | return r; /* return existing keyslot, so that wiping won't kill it */ | |
311 | } | |
312 | ||
c3a2a681 | 313 | /* If possible, verify the sealed data object. */ |
8d042bc4 LP |
314 | if ((!iovec_is_set(&pubkey) || signature_json) && !any_pcr_value_specified && !device_key) { |
315 | _cleanup_(iovec_done_erase) struct iovec secret2 = {}; | |
f0f4fcae LP |
316 | |
317 | log_debug("Unsealing for verification..."); | |
db7fdf15 | 318 | r = tpm2_unseal(tpm2_context, |
f0f4fcae | 319 | hash_pcr_mask, |
9e437994 | 320 | hash_pcr_bank, |
8d042bc4 | 321 | &pubkey, |
f0f4fcae LP |
322 | pubkey_pcr_mask, |
323 | signature_json, | |
324 | pin_str, | |
404aea78 | 325 | pcrlock_path ? &pcrlock_policy : NULL, |
9e437994 | 326 | /* primary_alg= */ 0, |
8d042bc4 LP |
327 | &blob, |
328 | &IOVEC_MAKE(policy.buffer, policy.size), | |
329 | &srk, | |
330 | &secret2); | |
f0f4fcae | 331 | if (r < 0) |
f9a0ee75 | 332 | return log_error_errno(r, "Failed to unseal secret using TPM2: %m"); |
5e521624 | 333 | |
8d042bc4 | 334 | if (iovec_memcmp(&secret, &secret2) != 0) |
f0f4fcae LP |
335 | return log_error_errno(SYNTHETIC_ERRNO(ENOTRECOVERABLE), "TPM2 seal/unseal verification failed."); |
336 | } | |
5e521624 LP |
337 | |
338 | /* let's base64 encode the key to use, for compat with homed (and it's easier to every type it in by keyboard, if that might end up being necessary. */ | |
8d042bc4 | 339 | base64_encoded_size = base64mem(secret.iov_base, secret.iov_len, &base64_encoded); |
5e476b85 LP |
340 | if (base64_encoded_size < 0) |
341 | return log_error_errno(base64_encoded_size, "Failed to base64 encode secret key: %m"); | |
5e521624 LP |
342 | |
343 | r = cryptsetup_set_minimal_pbkdf(cd); | |
344 | if (r < 0) | |
345 | return log_error_errno(r, "Failed to set minimal PBKDF: %m"); | |
346 | ||
347 | keyslot = crypt_keyslot_add_by_volume_key( | |
348 | cd, | |
349 | CRYPT_ANY_SLOT, | |
350 | volume_key, | |
351 | volume_key_size, | |
352 | base64_encoded, | |
5e476b85 | 353 | base64_encoded_size); |
5e521624 LP |
354 | if (keyslot < 0) |
355 | return log_error_errno(keyslot, "Failed to add new TPM2 key to %s: %m", node); | |
356 | ||
f0f4fcae LP |
357 | r = tpm2_make_luks2_json( |
358 | keyslot, | |
359 | hash_pcr_mask, | |
9e437994 | 360 | hash_pcr_bank, |
8d042bc4 | 361 | &pubkey, |
f0f4fcae | 362 | pubkey_pcr_mask, |
9e437994 | 363 | /* primary_alg= */ 0, |
8d042bc4 LP |
364 | &blob, |
365 | &IOVEC_MAKE(policy.buffer, policy.size), | |
366 | use_pin ? &IOVEC_MAKE(binary_salt, sizeof(binary_salt)) : NULL, | |
367 | &srk, | |
f0f4fcae LP |
368 | flags, |
369 | &v); | |
5e521624 LP |
370 | if (r < 0) |
371 | return log_error_errno(r, "Failed to prepare TPM2 JSON token object: %m"); | |
372 | ||
373 | r = cryptsetup_add_token_json(cd, v); | |
374 | if (r < 0) | |
375 | return log_error_errno(r, "Failed to add TPM2 JSON token to LUKS2 header: %m"); | |
376 | ||
377 | log_info("New TPM2 token enrolled as key slot %i.", keyslot); | |
378 | return keyslot; | |
379 | } |