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db9ecf05 | 1 | /* SPDX-License-Identifier: LGPL-2.1-or-later */ |
70a5db58 LP |
2 | |
3 | #include <linux/fs.h> | |
4 | #include <openssl/evp.h> | |
5 | #include <openssl/sha.h> | |
6 | #include <sys/ioctl.h> | |
7 | #include <sys/xattr.h> | |
8 | ||
9 | #include "errno-util.h" | |
10 | #include "fd-util.h" | |
11 | #include "hexdecoct.h" | |
12 | #include "homework-fscrypt.h" | |
65400de0 | 13 | #include "homework-mount.h" |
70a5db58 LP |
14 | #include "homework-quota.h" |
15 | #include "memory-util.h" | |
16 | #include "missing_keyctl.h" | |
17 | #include "missing_syscall.h" | |
18 | #include "mkdir.h" | |
65400de0 | 19 | #include "mount-util.h" |
70a5db58 LP |
20 | #include "nulstr-util.h" |
21 | #include "openssl-util.h" | |
22 | #include "parse-util.h" | |
23 | #include "process-util.h" | |
24 | #include "random-util.h" | |
25 | #include "rm-rf.h" | |
26 | #include "stdio-util.h" | |
27 | #include "strv.h" | |
28 | #include "tmpfile-util.h" | |
29 | #include "user-util.h" | |
30 | #include "xattr-util.h" | |
31 | ||
32 | static int fscrypt_upload_volume_key( | |
33 | const uint8_t key_descriptor[static FS_KEY_DESCRIPTOR_SIZE], | |
34 | const void *volume_key, | |
35 | size_t volume_key_size, | |
36 | key_serial_t where) { | |
37 | ||
38 | _cleanup_free_ char *hex = NULL; | |
39 | const char *description; | |
40 | struct fscrypt_key key; | |
41 | key_serial_t serial; | |
42 | ||
43 | assert(key_descriptor); | |
44 | assert(volume_key); | |
45 | assert(volume_key_size > 0); | |
46 | ||
47 | if (volume_key_size > sizeof(key.raw)) | |
48 | return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Volume key too long."); | |
49 | ||
50 | hex = hexmem(key_descriptor, FS_KEY_DESCRIPTOR_SIZE); | |
51 | if (!hex) | |
52 | return log_oom(); | |
53 | ||
54 | description = strjoina("fscrypt:", hex); | |
55 | ||
56 | key = (struct fscrypt_key) { | |
57 | .size = volume_key_size, | |
58 | }; | |
59 | memcpy(key.raw, volume_key, volume_key_size); | |
60 | ||
61 | /* Upload to the kernel */ | |
62 | serial = add_key("logon", description, &key, sizeof(key), where); | |
63 | explicit_bzero_safe(&key, sizeof(key)); | |
64 | ||
65 | if (serial < 0) | |
66 | return log_error_errno(errno, "Failed to install master key in keyring: %m"); | |
67 | ||
68 | log_info("Uploaded encryption key to kernel."); | |
69 | ||
70 | return 0; | |
71 | } | |
72 | ||
73 | static void calculate_key_descriptor( | |
74 | const void *key, | |
75 | size_t key_size, | |
76 | uint8_t ret_key_descriptor[static FS_KEY_DESCRIPTOR_SIZE]) { | |
77 | ||
78 | uint8_t hashed[512 / 8] = {}, hashed2[512 / 8] = {}; | |
79 | ||
80 | /* Derive the key descriptor from the volume key via double SHA512, in order to be compatible with e4crypt */ | |
81 | ||
82 | assert_se(SHA512(key, key_size, hashed) == hashed); | |
83 | assert_se(SHA512(hashed, sizeof(hashed), hashed2) == hashed2); | |
84 | ||
85 | assert_cc(sizeof(hashed2) >= FS_KEY_DESCRIPTOR_SIZE); | |
86 | ||
87 | memcpy(ret_key_descriptor, hashed2, FS_KEY_DESCRIPTOR_SIZE); | |
88 | } | |
89 | ||
90 | static int fscrypt_slot_try_one( | |
91 | const char *password, | |
92 | const void *salt, size_t salt_size, | |
93 | const void *encrypted, size_t encrypted_size, | |
94 | const uint8_t match_key_descriptor[static FS_KEY_DESCRIPTOR_SIZE], | |
95 | void **ret_decrypted, size_t *ret_decrypted_size) { | |
96 | ||
97 | ||
98 | _cleanup_(EVP_CIPHER_CTX_freep) EVP_CIPHER_CTX *context = NULL; | |
99 | _cleanup_(erase_and_freep) void *decrypted = NULL; | |
100 | uint8_t key_descriptor[FS_KEY_DESCRIPTOR_SIZE]; | |
101 | int decrypted_size_out1, decrypted_size_out2; | |
102 | uint8_t derived[512 / 8] = {}; | |
103 | size_t decrypted_size; | |
104 | const EVP_CIPHER *cc; | |
105 | int r; | |
106 | ||
107 | assert(password); | |
108 | assert(salt); | |
109 | assert(salt_size > 0); | |
110 | assert(encrypted); | |
111 | assert(encrypted_size > 0); | |
112 | assert(match_key_descriptor); | |
113 | ||
114 | /* Our construction is like this: | |
115 | * | |
116 | * 1. In each key slot we store a salt value plus the encrypted volume key | |
117 | * | |
118 | * 2. Unlocking is via calculating PBKDF2-HMAC-SHA512 of the supplied password (in combination with | |
119 | * the salt), then using the first 256 bit of the hash as key for decrypting the encrypted | |
120 | * volume key in AES256 counter mode. | |
121 | * | |
122 | * 3. Writing a password is similar: calculate PBKDF2-HMAC-SHA512 of the supplied password (in | |
123 | * combination with the salt), then encrypt the volume key in AES256 counter mode with the | |
124 | * resulting hash. | |
125 | */ | |
126 | ||
127 | if (PKCS5_PBKDF2_HMAC( | |
128 | password, strlen(password), | |
129 | salt, salt_size, | |
130 | 0xFFFF, EVP_sha512(), | |
131 | sizeof(derived), derived) != 1) { | |
132 | r = log_error_errno(SYNTHETIC_ERRNO(ENOTRECOVERABLE), "PBKDF2 failed"); | |
133 | goto finish; | |
134 | } | |
135 | ||
136 | context = EVP_CIPHER_CTX_new(); | |
137 | if (!context) { | |
138 | r = log_oom(); | |
139 | goto finish; | |
140 | } | |
141 | ||
142 | /* We use AES256 in counter mode */ | |
143 | assert_se(cc = EVP_aes_256_ctr()); | |
144 | ||
145 | /* We only use the first half of the derived key */ | |
146 | assert(sizeof(derived) >= (size_t) EVP_CIPHER_key_length(cc)); | |
147 | ||
148 | if (EVP_DecryptInit_ex(context, cc, NULL, derived, NULL) != 1) { | |
149 | r = log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Failed to initialize decryption context."); | |
150 | goto finish; | |
151 | } | |
152 | ||
153 | /* Flush out the derived key now, we don't need it anymore */ | |
154 | explicit_bzero_safe(derived, sizeof(derived)); | |
155 | ||
156 | decrypted_size = encrypted_size + EVP_CIPHER_key_length(cc) * 2; | |
157 | decrypted = malloc(decrypted_size); | |
158 | if (!decrypted) | |
159 | return log_oom(); | |
160 | ||
161 | if (EVP_DecryptUpdate(context, (uint8_t*) decrypted, &decrypted_size_out1, encrypted, encrypted_size) != 1) | |
162 | return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Failed to decrypt volume key."); | |
163 | ||
164 | assert((size_t) decrypted_size_out1 <= decrypted_size); | |
165 | ||
166 | if (EVP_DecryptFinal_ex(context, (uint8_t*) decrypted_size + decrypted_size_out1, &decrypted_size_out2) != 1) | |
167 | return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Failed to finish decryption of volume key."); | |
168 | ||
169 | assert((size_t) decrypted_size_out1 + (size_t) decrypted_size_out2 < decrypted_size); | |
170 | decrypted_size = (size_t) decrypted_size_out1 + (size_t) decrypted_size_out2; | |
171 | ||
172 | calculate_key_descriptor(decrypted, decrypted_size, key_descriptor); | |
173 | ||
174 | if (memcmp(key_descriptor, match_key_descriptor, FS_KEY_DESCRIPTOR_SIZE) != 0) | |
175 | return -ENOANO; /* don't log here */ | |
176 | ||
177 | r = fscrypt_upload_volume_key(key_descriptor, decrypted, decrypted_size, KEY_SPEC_THREAD_KEYRING); | |
178 | if (r < 0) | |
179 | return r; | |
180 | ||
181 | if (ret_decrypted) | |
182 | *ret_decrypted = TAKE_PTR(decrypted); | |
183 | if (ret_decrypted_size) | |
184 | *ret_decrypted_size = decrypted_size; | |
185 | ||
186 | return 0; | |
187 | ||
188 | finish: | |
189 | explicit_bzero_safe(derived, sizeof(derived)); | |
190 | return r; | |
191 | } | |
192 | ||
193 | static int fscrypt_slot_try_many( | |
194 | char **passwords, | |
195 | const void *salt, size_t salt_size, | |
196 | const void *encrypted, size_t encrypted_size, | |
197 | const uint8_t match_key_descriptor[static FS_KEY_DESCRIPTOR_SIZE], | |
198 | void **ret_decrypted, size_t *ret_decrypted_size) { | |
199 | ||
70a5db58 LP |
200 | int r; |
201 | ||
202 | STRV_FOREACH(i, passwords) { | |
203 | r = fscrypt_slot_try_one(*i, salt, salt_size, encrypted, encrypted_size, match_key_descriptor, ret_decrypted, ret_decrypted_size); | |
204 | if (r != -ENOANO) | |
205 | return r; | |
206 | } | |
207 | ||
208 | return -ENOANO; | |
209 | } | |
210 | ||
211 | static int fscrypt_setup( | |
7b78db28 | 212 | const PasswordCache *cache, |
70a5db58 LP |
213 | char **password, |
214 | HomeSetup *setup, | |
215 | void **ret_volume_key, | |
216 | size_t *ret_volume_key_size) { | |
217 | ||
218 | _cleanup_free_ char *xattr_buf = NULL; | |
70a5db58 LP |
219 | int r; |
220 | ||
221 | assert(setup); | |
222 | assert(setup->root_fd >= 0); | |
223 | ||
224 | r = flistxattr_malloc(setup->root_fd, &xattr_buf); | |
225 | if (r < 0) | |
226 | return log_error_errno(errno, "Failed to retrieve xattr list: %m"); | |
227 | ||
228 | NULSTR_FOREACH(xa, xattr_buf) { | |
229 | _cleanup_free_ void *salt = NULL, *encrypted = NULL; | |
230 | _cleanup_free_ char *value = NULL; | |
231 | size_t salt_size, encrypted_size; | |
232 | const char *nr, *e; | |
7b78db28 | 233 | char **list; |
70a5db58 LP |
234 | int n; |
235 | ||
236 | /* Check if this xattr has the format 'trusted.fscrypt_slot<nr>' where '<nr>' is a 32bit unsigned integer */ | |
237 | nr = startswith(xa, "trusted.fscrypt_slot"); | |
238 | if (!nr) | |
239 | continue; | |
240 | if (safe_atou32(nr, NULL) < 0) | |
241 | continue; | |
242 | ||
243 | n = fgetxattr_malloc(setup->root_fd, xa, &value); | |
244 | if (n == -ENODATA) /* deleted by now? */ | |
245 | continue; | |
246 | if (n < 0) | |
247 | return log_error_errno(n, "Failed to read %s xattr: %m", xa); | |
248 | ||
249 | e = memchr(value, ':', n); | |
250 | if (!e) | |
251 | return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "xattr %s lacks ':' separator: %m", xa); | |
252 | ||
253 | r = unbase64mem(value, e - value, &salt, &salt_size); | |
254 | if (r < 0) | |
255 | return log_error_errno(r, "Failed to decode salt of %s: %m", xa); | |
256 | r = unbase64mem(e+1, n - (e - value) - 1, &encrypted, &encrypted_size); | |
257 | if (r < 0) | |
258 | return log_error_errno(r, "Failed to decode encrypted key of %s: %m", xa); | |
259 | ||
7b78db28 LP |
260 | r = -ENOANO; |
261 | FOREACH_POINTER(list, cache->pkcs11_passwords, cache->fido2_passwords, password) { | |
70a5db58 | 262 | r = fscrypt_slot_try_many( |
7b78db28 | 263 | list, |
70a5db58 LP |
264 | salt, salt_size, |
265 | encrypted, encrypted_size, | |
266 | setup->fscrypt_key_descriptor, | |
267 | ret_volume_key, ret_volume_key_size); | |
7b78db28 LP |
268 | if (r != -ENOANO) |
269 | break; | |
270 | } | |
70a5db58 LP |
271 | if (r < 0) { |
272 | if (r != -ENOANO) | |
273 | return r; | |
274 | } else | |
275 | return 0; | |
276 | } | |
277 | ||
278 | return log_error_errno(SYNTHETIC_ERRNO(ENOKEY), "Failed to set up home directory with provided passwords."); | |
279 | } | |
280 | ||
aa0a6214 | 281 | int home_setup_fscrypt( |
70a5db58 | 282 | UserRecord *h, |
c00b2ddc LP |
283 | HomeSetup *setup, |
284 | const PasswordCache *cache) { | |
70a5db58 LP |
285 | |
286 | _cleanup_(erase_and_freep) void *volume_key = NULL; | |
287 | struct fscrypt_policy policy = {}; | |
288 | size_t volume_key_size = 0; | |
289 | const char *ip; | |
290 | int r; | |
291 | ||
292 | assert(h); | |
70a5db58 | 293 | assert(user_record_storage(h) == USER_FSCRYPT); |
65400de0 LP |
294 | assert(setup); |
295 | assert(setup->root_fd < 0); | |
70a5db58 LP |
296 | |
297 | assert_se(ip = user_record_image_path(h)); | |
298 | ||
299 | setup->root_fd = open(ip, O_RDONLY|O_CLOEXEC|O_DIRECTORY); | |
300 | if (setup->root_fd < 0) | |
301 | return log_error_errno(errno, "Failed to open home directory: %m"); | |
302 | ||
303 | if (ioctl(setup->root_fd, FS_IOC_GET_ENCRYPTION_POLICY, &policy) < 0) { | |
304 | if (errno == ENODATA) | |
305 | return log_error_errno(errno, "Home directory %s is not encrypted.", ip); | |
306 | if (ERRNO_IS_NOT_SUPPORTED(errno)) { | |
307 | log_error_errno(errno, "File system does not support fscrypt: %m"); | |
308 | return -ENOLINK; /* make recognizable */ | |
309 | } | |
310 | return log_error_errno(errno, "Failed to acquire encryption policy of %s: %m", ip); | |
311 | } | |
312 | ||
313 | memcpy(setup->fscrypt_key_descriptor, policy.master_key_descriptor, FS_KEY_DESCRIPTOR_SIZE); | |
314 | ||
315 | r = fscrypt_setup( | |
7b78db28 | 316 | cache, |
70a5db58 LP |
317 | h->password, |
318 | setup, | |
319 | &volume_key, | |
320 | &volume_key_size); | |
321 | if (r < 0) | |
322 | return r; | |
323 | ||
324 | /* Also install the access key in the user's own keyring */ | |
325 | ||
326 | if (uid_is_valid(h->uid)) { | |
7e0ed2e9 SB |
327 | r = safe_fork("(sd-addkey)", |
328 | FORK_RESET_SIGNALS|FORK_CLOSE_ALL_FDS|FORK_DEATHSIG|FORK_LOG|FORK_WAIT|FORK_REOPEN_LOG, | |
329 | NULL); | |
70a5db58 LP |
330 | if (r < 0) |
331 | return log_error_errno(r, "Failed install encryption key in user's keyring: %m"); | |
332 | if (r == 0) { | |
333 | gid_t gid; | |
334 | ||
335 | /* Child */ | |
336 | ||
337 | gid = user_record_gid(h); | |
338 | if (setresgid(gid, gid, gid) < 0) { | |
339 | log_error_errno(errno, "Failed to change GID to " GID_FMT ": %m", gid); | |
340 | _exit(EXIT_FAILURE); | |
341 | } | |
342 | ||
343 | if (setgroups(0, NULL) < 0) { | |
344 | log_error_errno(errno, "Failed to reset auxiliary groups list: %m"); | |
345 | _exit(EXIT_FAILURE); | |
346 | } | |
347 | ||
348 | if (setresuid(h->uid, h->uid, h->uid) < 0) { | |
349 | log_error_errno(errno, "Failed to change UID to " UID_FMT ": %m", h->uid); | |
350 | _exit(EXIT_FAILURE); | |
351 | } | |
352 | ||
353 | r = fscrypt_upload_volume_key( | |
354 | setup->fscrypt_key_descriptor, | |
355 | volume_key, | |
356 | volume_key_size, | |
357 | KEY_SPEC_USER_KEYRING); | |
358 | if (r < 0) | |
359 | _exit(EXIT_FAILURE); | |
360 | ||
361 | _exit(EXIT_SUCCESS); | |
362 | } | |
363 | } | |
364 | ||
65400de0 LP |
365 | /* We'll bind mount the image directory to a new mount point where we'll start adjusting it. Only |
366 | * once that's complete we'll move the thing to its final place eventually. */ | |
367 | r = home_unshare_and_mkdir(); | |
368 | if (r < 0) | |
369 | return r; | |
370 | ||
371 | r = mount_follow_verbose(LOG_ERR, ip, HOME_RUNTIME_WORK_DIR, NULL, MS_BIND, NULL); | |
372 | if (r < 0) | |
373 | return r; | |
374 | ||
375 | setup->undo_mount = true; | |
376 | ||
377 | /* Turn off any form of propagation for this */ | |
378 | r = mount_nofollow_verbose(LOG_ERR, NULL, HOME_RUNTIME_WORK_DIR, NULL, MS_PRIVATE, NULL); | |
379 | if (r < 0) | |
380 | return r; | |
381 | ||
382 | /* Adjust MS_SUID and similar flags */ | |
383 | r = mount_nofollow_verbose(LOG_ERR, NULL, HOME_RUNTIME_WORK_DIR, NULL, MS_BIND|MS_REMOUNT|user_record_mount_flags(h), NULL); | |
384 | if (r < 0) | |
385 | return r; | |
386 | ||
387 | safe_close(setup->root_fd); | |
388 | setup->root_fd = open(HOME_RUNTIME_WORK_DIR, O_RDONLY|O_CLOEXEC|O_DIRECTORY|O_NOFOLLOW); | |
389 | if (setup->root_fd < 0) | |
390 | return log_error_errno(errno, "Failed to open home directory: %m"); | |
391 | ||
70a5db58 LP |
392 | return 0; |
393 | } | |
394 | ||
395 | static int fscrypt_slot_set( | |
396 | int root_fd, | |
397 | const void *volume_key, | |
398 | size_t volume_key_size, | |
399 | const char *password, | |
400 | uint32_t nr) { | |
401 | ||
402 | _cleanup_free_ char *salt_base64 = NULL, *encrypted_base64 = NULL, *joined = NULL; | |
403 | char label[STRLEN("trusted.fscrypt_slot") + DECIMAL_STR_MAX(nr) + 1]; | |
404 | _cleanup_(EVP_CIPHER_CTX_freep) EVP_CIPHER_CTX *context = NULL; | |
405 | int r, encrypted_size_out1, encrypted_size_out2; | |
406 | uint8_t salt[64], derived[512 / 8] = {}; | |
407 | _cleanup_free_ void *encrypted = NULL; | |
408 | const EVP_CIPHER *cc; | |
409 | size_t encrypted_size; | |
410 | ||
87cb1ab6 | 411 | r = crypto_random_bytes(salt, sizeof(salt)); |
70a5db58 LP |
412 | if (r < 0) |
413 | return log_error_errno(r, "Failed to generate salt: %m"); | |
414 | ||
415 | if (PKCS5_PBKDF2_HMAC( | |
416 | password, strlen(password), | |
417 | salt, sizeof(salt), | |
418 | 0xFFFF, EVP_sha512(), | |
419 | sizeof(derived), derived) != 1) { | |
420 | r = log_error_errno(SYNTHETIC_ERRNO(ENOTRECOVERABLE), "PBKDF2 failed"); | |
421 | goto finish; | |
422 | } | |
423 | ||
424 | context = EVP_CIPHER_CTX_new(); | |
425 | if (!context) { | |
426 | r = log_oom(); | |
427 | goto finish; | |
428 | } | |
429 | ||
430 | /* We use AES256 in counter mode */ | |
431 | cc = EVP_aes_256_ctr(); | |
432 | ||
433 | /* We only use the first half of the derived key */ | |
434 | assert(sizeof(derived) >= (size_t) EVP_CIPHER_key_length(cc)); | |
435 | ||
436 | if (EVP_EncryptInit_ex(context, cc, NULL, derived, NULL) != 1) { | |
437 | r = log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Failed to initialize encryption context."); | |
438 | goto finish; | |
439 | } | |
440 | ||
441 | /* Flush out the derived key now, we don't need it anymore */ | |
442 | explicit_bzero_safe(derived, sizeof(derived)); | |
443 | ||
444 | encrypted_size = volume_key_size + EVP_CIPHER_key_length(cc) * 2; | |
445 | encrypted = malloc(encrypted_size); | |
446 | if (!encrypted) | |
447 | return log_oom(); | |
448 | ||
449 | if (EVP_EncryptUpdate(context, (uint8_t*) encrypted, &encrypted_size_out1, volume_key, volume_key_size) != 1) | |
450 | return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Failed to encrypt volume key."); | |
451 | ||
452 | assert((size_t) encrypted_size_out1 <= encrypted_size); | |
453 | ||
454 | if (EVP_EncryptFinal_ex(context, (uint8_t*) encrypted_size + encrypted_size_out1, &encrypted_size_out2) != 1) | |
455 | return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Failed to finish encryption of volume key."); | |
456 | ||
457 | assert((size_t) encrypted_size_out1 + (size_t) encrypted_size_out2 < encrypted_size); | |
458 | encrypted_size = (size_t) encrypted_size_out1 + (size_t) encrypted_size_out2; | |
459 | ||
460 | r = base64mem(salt, sizeof(salt), &salt_base64); | |
461 | if (r < 0) | |
462 | return log_oom(); | |
463 | ||
464 | r = base64mem(encrypted, encrypted_size, &encrypted_base64); | |
465 | if (r < 0) | |
466 | return log_oom(); | |
467 | ||
468 | joined = strjoin(salt_base64, ":", encrypted_base64); | |
469 | if (!joined) | |
470 | return log_oom(); | |
471 | ||
472 | xsprintf(label, "trusted.fscrypt_slot%" PRIu32, nr); | |
473 | if (fsetxattr(root_fd, label, joined, strlen(joined), 0) < 0) | |
474 | return log_error_errno(errno, "Failed to write xattr %s: %m", label); | |
475 | ||
476 | log_info("Written key slot %s.", label); | |
477 | ||
478 | return 0; | |
479 | ||
480 | finish: | |
481 | explicit_bzero_safe(derived, sizeof(derived)); | |
482 | return r; | |
483 | } | |
484 | ||
485 | int home_create_fscrypt( | |
486 | UserRecord *h, | |
655807f5 | 487 | HomeSetup *setup, |
70a5db58 LP |
488 | char **effective_passwords, |
489 | UserRecord **ret_home) { | |
490 | ||
491 | _cleanup_(rm_rf_physical_and_freep) char *temporary = NULL; | |
492 | _cleanup_(user_record_unrefp) UserRecord *new_home = NULL; | |
493 | _cleanup_(erase_and_freep) void *volume_key = NULL; | |
65400de0 | 494 | _cleanup_close_ int mount_fd = -1; |
70a5db58 LP |
495 | struct fscrypt_policy policy = {}; |
496 | size_t volume_key_size = 512 / 8; | |
70a5db58 LP |
497 | _cleanup_free_ char *d = NULL; |
498 | uint32_t nr = 0; | |
499 | const char *ip; | |
70a5db58 LP |
500 | int r; |
501 | ||
502 | assert(h); | |
503 | assert(user_record_storage(h) == USER_FSCRYPT); | |
655807f5 | 504 | assert(setup); |
70a5db58 LP |
505 | assert(ret_home); |
506 | ||
507 | assert_se(ip = user_record_image_path(h)); | |
508 | ||
509 | r = tempfn_random(ip, "homework", &d); | |
510 | if (r < 0) | |
511 | return log_error_errno(r, "Failed to allocate temporary directory: %m"); | |
512 | ||
513 | (void) mkdir_parents(d, 0755); | |
514 | ||
515 | if (mkdir(d, 0700) < 0) | |
516 | return log_error_errno(errno, "Failed to create temporary home directory %s: %m", d); | |
517 | ||
518 | temporary = TAKE_PTR(d); /* Needs to be destroyed now */ | |
519 | ||
65400de0 LP |
520 | r = home_unshare_and_mkdir(); |
521 | if (r < 0) | |
522 | return r; | |
523 | ||
655807f5 LP |
524 | setup->root_fd = open(temporary, O_RDONLY|O_CLOEXEC|O_DIRECTORY|O_NOFOLLOW); |
525 | if (setup->root_fd < 0) | |
70a5db58 LP |
526 | return log_error_errno(errno, "Failed to open temporary home directory: %m"); |
527 | ||
655807f5 | 528 | if (ioctl(setup->root_fd, FS_IOC_GET_ENCRYPTION_POLICY, &policy) < 0) { |
70a5db58 LP |
529 | if (ERRNO_IS_NOT_SUPPORTED(errno)) { |
530 | log_error_errno(errno, "File system does not support fscrypt: %m"); | |
531 | return -ENOLINK; /* make recognizable */ | |
532 | } | |
533 | if (errno != ENODATA) | |
534 | return log_error_errno(errno, "Failed to get fscrypt policy of directory: %m"); | |
535 | } else | |
536 | return log_error_errno(SYNTHETIC_ERRNO(EBUSY), "Parent of %s already encrypted, refusing.", d); | |
537 | ||
538 | volume_key = malloc(volume_key_size); | |
539 | if (!volume_key) | |
540 | return log_oom(); | |
541 | ||
87cb1ab6 | 542 | r = crypto_random_bytes(volume_key, volume_key_size); |
70a5db58 LP |
543 | if (r < 0) |
544 | return log_error_errno(r, "Failed to acquire volume key: %m"); | |
545 | ||
546 | log_info("Generated volume key of size %zu.", volume_key_size); | |
547 | ||
548 | policy = (struct fscrypt_policy) { | |
549 | .contents_encryption_mode = FS_ENCRYPTION_MODE_AES_256_XTS, | |
550 | .filenames_encryption_mode = FS_ENCRYPTION_MODE_AES_256_CTS, | |
551 | .flags = FS_POLICY_FLAGS_PAD_32, | |
552 | }; | |
553 | ||
554 | calculate_key_descriptor(volume_key, volume_key_size, policy.master_key_descriptor); | |
555 | ||
556 | r = fscrypt_upload_volume_key(policy.master_key_descriptor, volume_key, volume_key_size, KEY_SPEC_THREAD_KEYRING); | |
557 | if (r < 0) | |
558 | return r; | |
559 | ||
560 | log_info("Uploaded volume key to kernel."); | |
561 | ||
655807f5 | 562 | if (ioctl(setup->root_fd, FS_IOC_SET_ENCRYPTION_POLICY, &policy) < 0) |
70a5db58 LP |
563 | return log_error_errno(errno, "Failed to set fscrypt policy on directory: %m"); |
564 | ||
565 | log_info("Encryption policy set."); | |
566 | ||
567 | STRV_FOREACH(i, effective_passwords) { | |
655807f5 | 568 | r = fscrypt_slot_set(setup->root_fd, volume_key, volume_key_size, *i, nr); |
70a5db58 LP |
569 | if (r < 0) |
570 | return r; | |
571 | ||
572 | nr++; | |
573 | } | |
574 | ||
575 | (void) home_update_quota_classic(h, temporary); | |
576 | ||
65400de0 LP |
577 | r = home_shift_uid(setup->root_fd, HOME_RUNTIME_WORK_DIR, h->uid, h->uid, &mount_fd); |
578 | if (r > 0) | |
579 | setup->undo_mount = true; /* If uidmaps worked we have a mount to undo again */ | |
580 | ||
581 | if (mount_fd >= 0) { | |
582 | /* If we have established a new mount, then we can use that as new root fd to our home directory. */ | |
583 | safe_close(setup->root_fd); | |
584 | ||
585 | setup->root_fd = fd_reopen(mount_fd, O_RDONLY|O_CLOEXEC|O_DIRECTORY); | |
586 | if (setup->root_fd < 0) | |
587 | return log_error_errno(setup->root_fd, "Unable to convert mount fd into proper directory fd: %m"); | |
588 | ||
589 | mount_fd = safe_close(mount_fd); | |
590 | } | |
591 | ||
655807f5 | 592 | r = home_populate(h, setup->root_fd); |
70a5db58 LP |
593 | if (r < 0) |
594 | return r; | |
595 | ||
655807f5 | 596 | r = home_sync_and_statfs(setup->root_fd, NULL); |
70a5db58 LP |
597 | if (r < 0) |
598 | return r; | |
599 | ||
bfc0cc1a | 600 | r = user_record_clone(h, USER_RECORD_LOAD_MASK_SECRET|USER_RECORD_PERMISSIVE, &new_home); |
70a5db58 LP |
601 | if (r < 0) |
602 | return log_error_errno(r, "Failed to clone record: %m"); | |
603 | ||
604 | r = user_record_add_binding( | |
605 | new_home, | |
606 | USER_FSCRYPT, | |
607 | ip, | |
608 | SD_ID128_NULL, | |
609 | SD_ID128_NULL, | |
610 | SD_ID128_NULL, | |
611 | NULL, | |
612 | NULL, | |
613 | UINT64_MAX, | |
614 | NULL, | |
615 | NULL, | |
616 | h->uid, | |
617 | (gid_t) h->uid); | |
618 | if (r < 0) | |
619 | return log_error_errno(r, "Failed to add binding to record: %m"); | |
620 | ||
65400de0 LP |
621 | setup->root_fd = safe_close(setup->root_fd); |
622 | ||
623 | r = home_setup_undo_mount(setup, LOG_ERR); | |
624 | if (r < 0) | |
625 | return r; | |
626 | ||
70a5db58 LP |
627 | if (rename(temporary, ip) < 0) |
628 | return log_error_errno(errno, "Failed to rename %s to %s: %m", temporary, ip); | |
629 | ||
630 | temporary = mfree(temporary); | |
631 | ||
632 | log_info("Everything completed."); | |
633 | ||
634 | *ret_home = TAKE_PTR(new_home); | |
635 | return 0; | |
636 | } | |
637 | ||
638 | int home_passwd_fscrypt( | |
639 | UserRecord *h, | |
640 | HomeSetup *setup, | |
37a1bf7f | 641 | const PasswordCache *cache, /* the passwords acquired via PKCS#11/FIDO2 security tokens */ |
70a5db58 LP |
642 | char **effective_passwords /* new passwords */) { |
643 | ||
644 | _cleanup_(erase_and_freep) void *volume_key = NULL; | |
645 | _cleanup_free_ char *xattr_buf = NULL; | |
646 | size_t volume_key_size = 0; | |
647 | uint32_t slot = 0; | |
70a5db58 LP |
648 | int r; |
649 | ||
650 | assert(h); | |
651 | assert(user_record_storage(h) == USER_FSCRYPT); | |
652 | assert(setup); | |
653 | ||
654 | r = fscrypt_setup( | |
7b78db28 | 655 | cache, |
70a5db58 LP |
656 | h->password, |
657 | setup, | |
658 | &volume_key, | |
659 | &volume_key_size); | |
660 | if (r < 0) | |
661 | return r; | |
662 | ||
663 | STRV_FOREACH(p, effective_passwords) { | |
664 | r = fscrypt_slot_set(setup->root_fd, volume_key, volume_key_size, *p, slot); | |
665 | if (r < 0) | |
666 | return r; | |
667 | ||
668 | slot++; | |
669 | } | |
670 | ||
671 | r = flistxattr_malloc(setup->root_fd, &xattr_buf); | |
672 | if (r < 0) | |
673 | return log_error_errno(errno, "Failed to retrieve xattr list: %m"); | |
674 | ||
675 | NULSTR_FOREACH(xa, xattr_buf) { | |
676 | const char *nr; | |
677 | uint32_t z; | |
678 | ||
679 | /* Check if this xattr has the format 'trusted.fscrypt_slot<nr>' where '<nr>' is a 32bit unsigned integer */ | |
680 | nr = startswith(xa, "trusted.fscrypt_slot"); | |
681 | if (!nr) | |
682 | continue; | |
683 | if (safe_atou32(nr, &z) < 0) | |
684 | continue; | |
685 | ||
686 | if (z < slot) | |
687 | continue; | |
688 | ||
689 | if (fremovexattr(setup->root_fd, xa) < 0) | |
70a5db58 LP |
690 | if (errno != ENODATA) |
691 | log_warning_errno(errno, "Failed to remove xattr %s: %m", xa); | |
692 | } | |
693 | ||
694 | return 0; | |
695 | } |