1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * This contains functions for filename crypto management 4 * 5 * Copyright (C) 2015, Google, Inc. 6 * Copyright (C) 2015, Motorola Mobility 7 * 8 * Written by Uday Savagaonkar, 2014. 9 * Modified by Jaegeuk Kim, 2015. 10 * 11 * This has not yet undergone a rigorous security audit. 12 */ 13 14 #include <crypto/hash.h> 15 #include <crypto/sha2.h> 16 #include <crypto/skcipher.h> 17 #include <linux/export.h> 18 #include <linux/namei.h> 19 #include <linux/scatterlist.h> 20 21 #include "fscrypt_private.h" 22 23 /* 24 * The minimum message length (input and output length), in bytes, for all 25 * filenames encryption modes. Filenames shorter than this will be zero-padded 26 * before being encrypted. 27 */ 28 #define FSCRYPT_FNAME_MIN_MSG_LEN 16 29 30 /* 31 * struct fscrypt_nokey_name - identifier for directory entry when key is absent 32 * 33 * When userspace lists an encrypted directory without access to the key, the 34 * filesystem must present a unique "no-key name" for each filename that allows 35 * it to find the directory entry again if requested. Naively, that would just 36 * mean using the ciphertext filenames. However, since the ciphertext filenames 37 * can contain illegal characters ('\0' and '/'), they must be encoded in some 38 * way. We use base64url. But that can cause names to exceed NAME_MAX (255 39 * bytes), so we also need to use a strong hash to abbreviate long names. 40 * 41 * The filesystem may also need another kind of hash, the "dirhash", to quickly 42 * find the directory entry. Since filesystems normally compute the dirhash 43 * over the on-disk filename (i.e. the ciphertext), it's not computable from 44 * no-key names that abbreviate the ciphertext using the strong hash to fit in 45 * NAME_MAX. It's also not computable if it's a keyed hash taken over the 46 * plaintext (but it may still be available in the on-disk directory entry); 47 * casefolded directories use this type of dirhash. At least in these cases, 48 * each no-key name must include the name's dirhash too. 49 * 50 * To meet all these requirements, we base64url-encode the following 51 * variable-length structure. It contains the dirhash, or 0's if the filesystem 52 * didn't provide one; up to 149 bytes of the ciphertext name; and for 53 * ciphertexts longer than 149 bytes, also the SHA-256 of the remaining bytes. 54 * 55 * This ensures that each no-key name contains everything needed to find the 56 * directory entry again, contains only legal characters, doesn't exceed 57 * NAME_MAX, is unambiguous unless there's a SHA-256 collision, and that we only 58 * take the performance hit of SHA-256 on very long filenames (which are rare). 59 */ 60 struct fscrypt_nokey_name { 61 u32 dirhash[2]; 62 u8 bytes[149]; 63 u8 sha256[SHA256_DIGEST_SIZE]; 64 }; /* 189 bytes => 252 bytes base64url-encoded, which is <= NAME_MAX (255) */ 65 66 /* 67 * Decoded size of max-size no-key name, i.e. a name that was abbreviated using 68 * the strong hash and thus includes the 'sha256' field. This isn't simply 69 * sizeof(struct fscrypt_nokey_name), as the padding at the end isn't included. 70 */ 71 #define FSCRYPT_NOKEY_NAME_MAX offsetofend(struct fscrypt_nokey_name, sha256) 72 73 /* Encoded size of max-size no-key name */ 74 #define FSCRYPT_NOKEY_NAME_MAX_ENCODED \ 75 FSCRYPT_BASE64URL_CHARS(FSCRYPT_NOKEY_NAME_MAX) 76 77 static inline bool fscrypt_is_dot_dotdot(const struct qstr *str) 78 { 79 return is_dot_dotdot(str->name, str->len); 80 } 81 82 /** 83 * fscrypt_fname_encrypt() - encrypt a filename 84 * @inode: inode of the parent directory (for regular filenames) 85 * or of the symlink (for symlink targets). Key must already be 86 * set up. 87 * @iname: the filename to encrypt 88 * @out: (output) the encrypted filename 89 * @olen: size of the encrypted filename. It must be at least @iname->len. 90 * Any extra space is filled with NUL padding before encryption. 91 * 92 * Return: 0 on success, -errno on failure 93 */ 94 int fscrypt_fname_encrypt(const struct inode *inode, const struct qstr *iname, 95 u8 *out, unsigned int olen) 96 { 97 const struct fscrypt_inode_info *ci = fscrypt_get_inode_info_raw(inode); 98 struct crypto_sync_skcipher *tfm = ci->ci_enc_key.tfm; 99 SYNC_SKCIPHER_REQUEST_ON_STACK(req, tfm); 100 union fscrypt_iv iv; 101 struct scatterlist sg; 102 int err; 103 104 /* 105 * Copy the filename to the output buffer for encrypting in-place and 106 * pad it with the needed number of NUL bytes. 107 */ 108 if (WARN_ON_ONCE(olen < iname->len)) 109 return -ENOBUFS; 110 memcpy(out, iname->name, iname->len); 111 memset(out + iname->len, 0, olen - iname->len); 112 113 fscrypt_generate_iv(&iv, 0, ci); 114 115 skcipher_request_set_callback( 116 req, CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP, 117 NULL, NULL); 118 sg_init_one(&sg, out, olen); 119 skcipher_request_set_crypt(req, &sg, &sg, olen, &iv); 120 err = crypto_skcipher_encrypt(req); 121 if (err) 122 fscrypt_err(inode, "Filename encryption failed: %d", err); 123 return err; 124 } 125 EXPORT_SYMBOL_GPL(fscrypt_fname_encrypt); 126 127 /** 128 * fname_decrypt() - decrypt a filename 129 * @inode: inode of the parent directory (for regular filenames) 130 * or of the symlink (for symlink targets) 131 * @iname: the encrypted filename to decrypt 132 * @oname: (output) the decrypted filename. The caller must have allocated 133 * enough space for this, e.g. using fscrypt_fname_alloc_buffer(). 134 * 135 * Return: 0 on success, -errno on failure 136 */ 137 static int fname_decrypt(const struct inode *inode, 138 const struct fscrypt_str *iname, 139 struct fscrypt_str *oname) 140 { 141 const struct fscrypt_inode_info *ci = fscrypt_get_inode_info_raw(inode); 142 struct crypto_sync_skcipher *tfm = ci->ci_enc_key.tfm; 143 SYNC_SKCIPHER_REQUEST_ON_STACK(req, tfm); 144 union fscrypt_iv iv; 145 struct scatterlist src_sg, dst_sg; 146 int err; 147 148 fscrypt_generate_iv(&iv, 0, ci); 149 150 skcipher_request_set_callback( 151 req, CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP, 152 NULL, NULL); 153 sg_init_one(&src_sg, iname->name, iname->len); 154 sg_init_one(&dst_sg, oname->name, oname->len); 155 skcipher_request_set_crypt(req, &src_sg, &dst_sg, iname->len, &iv); 156 err = crypto_skcipher_decrypt(req); 157 if (err) { 158 fscrypt_err(inode, "Filename decryption failed: %d", err); 159 return err; 160 } 161 162 oname->len = strnlen(oname->name, iname->len); 163 return 0; 164 } 165 166 static const char base64url_table[65] = 167 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_"; 168 169 #define FSCRYPT_BASE64URL_CHARS(nbytes) DIV_ROUND_UP((nbytes) * 4, 3) 170 171 /** 172 * fscrypt_base64url_encode() - base64url-encode some binary data 173 * @src: the binary data to encode 174 * @srclen: the length of @src in bytes 175 * @dst: (output) the base64url-encoded string. Not NUL-terminated. 176 * 177 * Encodes data using base64url encoding, i.e. the "Base 64 Encoding with URL 178 * and Filename Safe Alphabet" specified by RFC 4648. '='-padding isn't used, 179 * as it's unneeded and not required by the RFC. base64url is used instead of 180 * base64 to avoid the '/' character, which isn't allowed in filenames. 181 * 182 * Return: the length of the resulting base64url-encoded string in bytes. 183 * This will be equal to FSCRYPT_BASE64URL_CHARS(srclen). 184 */ 185 static int fscrypt_base64url_encode(const u8 *src, int srclen, char *dst) 186 { 187 u32 ac = 0; 188 int bits = 0; 189 int i; 190 char *cp = dst; 191 192 for (i = 0; i < srclen; i++) { 193 ac = (ac << 8) | src[i]; 194 bits += 8; 195 do { 196 bits -= 6; 197 *cp++ = base64url_table[(ac >> bits) & 0x3f]; 198 } while (bits >= 6); 199 } 200 if (bits) 201 *cp++ = base64url_table[(ac << (6 - bits)) & 0x3f]; 202 return cp - dst; 203 } 204 205 /** 206 * fscrypt_base64url_decode() - base64url-decode a string 207 * @src: the string to decode. Doesn't need to be NUL-terminated. 208 * @srclen: the length of @src in bytes 209 * @dst: (output) the decoded binary data 210 * 211 * Decodes a string using base64url encoding, i.e. the "Base 64 Encoding with 212 * URL and Filename Safe Alphabet" specified by RFC 4648. '='-padding isn't 213 * accepted, nor are non-encoding characters such as whitespace. 214 * 215 * This implementation hasn't been optimized for performance. 216 * 217 * Return: the length of the resulting decoded binary data in bytes, 218 * or -1 if the string isn't a valid base64url string. 219 */ 220 static int fscrypt_base64url_decode(const char *src, int srclen, u8 *dst) 221 { 222 u32 ac = 0; 223 int bits = 0; 224 int i; 225 u8 *bp = dst; 226 227 for (i = 0; i < srclen; i++) { 228 const char *p = strchr(base64url_table, src[i]); 229 230 if (p == NULL || src[i] == 0) 231 return -1; 232 ac = (ac << 6) | (p - base64url_table); 233 bits += 6; 234 if (bits >= 8) { 235 bits -= 8; 236 *bp++ = (u8)(ac >> bits); 237 } 238 } 239 if (ac & ((1 << bits) - 1)) 240 return -1; 241 return bp - dst; 242 } 243 244 bool __fscrypt_fname_encrypted_size(const union fscrypt_policy *policy, 245 u32 orig_len, u32 max_len, 246 u32 *encrypted_len_ret) 247 { 248 int padding = 4 << (fscrypt_policy_flags(policy) & 249 FSCRYPT_POLICY_FLAGS_PAD_MASK); 250 u32 encrypted_len; 251 252 if (orig_len > max_len) 253 return false; 254 encrypted_len = max_t(u32, orig_len, FSCRYPT_FNAME_MIN_MSG_LEN); 255 encrypted_len = round_up(encrypted_len, padding); 256 *encrypted_len_ret = min(encrypted_len, max_len); 257 return true; 258 } 259 260 /** 261 * fscrypt_fname_encrypted_size() - calculate length of encrypted filename 262 * @inode: parent inode of dentry name being encrypted. Key must 263 * already be set up. 264 * @orig_len: length of the original filename 265 * @max_len: maximum length to return 266 * @encrypted_len_ret: where calculated length should be returned (on success) 267 * 268 * Filenames that are shorter than the maximum length may have their lengths 269 * increased slightly by encryption, due to padding that is applied. 270 * 271 * Return: false if the orig_len is greater than max_len. Otherwise, true and 272 * fill out encrypted_len_ret with the length (up to max_len). 273 */ 274 bool fscrypt_fname_encrypted_size(const struct inode *inode, u32 orig_len, 275 u32 max_len, u32 *encrypted_len_ret) 276 { 277 const struct fscrypt_inode_info *ci = fscrypt_get_inode_info_raw(inode); 278 279 return __fscrypt_fname_encrypted_size(&ci->ci_policy, orig_len, max_len, 280 encrypted_len_ret); 281 } 282 EXPORT_SYMBOL_GPL(fscrypt_fname_encrypted_size); 283 284 /** 285 * fscrypt_fname_alloc_buffer() - allocate a buffer for presented filenames 286 * @max_encrypted_len: maximum length of encrypted filenames the buffer will be 287 * used to present 288 * @crypto_str: (output) buffer to allocate 289 * 290 * Allocate a buffer that is large enough to hold any decrypted or encoded 291 * filename (null-terminated), for the given maximum encrypted filename length. 292 * 293 * Return: 0 on success, -errno on failure 294 */ 295 int fscrypt_fname_alloc_buffer(u32 max_encrypted_len, 296 struct fscrypt_str *crypto_str) 297 { 298 u32 max_presented_len = max_t(u32, FSCRYPT_NOKEY_NAME_MAX_ENCODED, 299 max_encrypted_len); 300 301 crypto_str->name = kmalloc(max_presented_len + 1, GFP_NOFS); 302 if (!crypto_str->name) 303 return -ENOMEM; 304 crypto_str->len = max_presented_len; 305 return 0; 306 } 307 EXPORT_SYMBOL(fscrypt_fname_alloc_buffer); 308 309 /** 310 * fscrypt_fname_free_buffer() - free a buffer for presented filenames 311 * @crypto_str: the buffer to free 312 * 313 * Free a buffer that was allocated by fscrypt_fname_alloc_buffer(). 314 */ 315 void fscrypt_fname_free_buffer(struct fscrypt_str *crypto_str) 316 { 317 if (!crypto_str) 318 return; 319 kfree(crypto_str->name); 320 crypto_str->name = NULL; 321 } 322 EXPORT_SYMBOL(fscrypt_fname_free_buffer); 323 324 /** 325 * fscrypt_fname_disk_to_usr() - convert an encrypted filename to 326 * user-presentable form 327 * @inode: inode of the parent directory (for regular filenames) 328 * or of the symlink (for symlink targets) 329 * @hash: first part of the name's dirhash, if applicable. This only needs to 330 * be provided if the filename is located in an indexed directory whose 331 * encryption key may be unavailable. Not needed for symlink targets. 332 * @minor_hash: second part of the name's dirhash, if applicable 333 * @iname: encrypted filename to convert. May also be "." or "..", which 334 * aren't actually encrypted. 335 * @oname: output buffer for the user-presentable filename. The caller must 336 * have allocated enough space for this, e.g. using 337 * fscrypt_fname_alloc_buffer(). 338 * 339 * If the key is available, we'll decrypt the disk name. Otherwise, we'll 340 * encode it for presentation in fscrypt_nokey_name format. 341 * See struct fscrypt_nokey_name for details. 342 * 343 * Return: 0 on success, -errno on failure 344 */ 345 int fscrypt_fname_disk_to_usr(const struct inode *inode, 346 u32 hash, u32 minor_hash, 347 const struct fscrypt_str *iname, 348 struct fscrypt_str *oname) 349 { 350 const struct qstr qname = FSTR_TO_QSTR(iname); 351 struct fscrypt_nokey_name nokey_name; 352 u32 size; /* size of the unencoded no-key name */ 353 354 if (fscrypt_is_dot_dotdot(&qname)) { 355 oname->name[0] = '.'; 356 oname->name[iname->len - 1] = '.'; 357 oname->len = iname->len; 358 return 0; 359 } 360 361 if (iname->len < FSCRYPT_FNAME_MIN_MSG_LEN) 362 return -EUCLEAN; 363 364 if (fscrypt_has_encryption_key(inode)) 365 return fname_decrypt(inode, iname, oname); 366 367 /* 368 * Sanity check that struct fscrypt_nokey_name doesn't have padding 369 * between fields and that its encoded size never exceeds NAME_MAX. 370 */ 371 BUILD_BUG_ON(offsetofend(struct fscrypt_nokey_name, dirhash) != 372 offsetof(struct fscrypt_nokey_name, bytes)); 373 BUILD_BUG_ON(offsetofend(struct fscrypt_nokey_name, bytes) != 374 offsetof(struct fscrypt_nokey_name, sha256)); 375 BUILD_BUG_ON(FSCRYPT_NOKEY_NAME_MAX_ENCODED > NAME_MAX); 376 377 nokey_name.dirhash[0] = hash; 378 nokey_name.dirhash[1] = minor_hash; 379 380 if (iname->len <= sizeof(nokey_name.bytes)) { 381 memcpy(nokey_name.bytes, iname->name, iname->len); 382 size = offsetof(struct fscrypt_nokey_name, bytes[iname->len]); 383 } else { 384 memcpy(nokey_name.bytes, iname->name, sizeof(nokey_name.bytes)); 385 /* Compute strong hash of remaining part of name. */ 386 sha256(&iname->name[sizeof(nokey_name.bytes)], 387 iname->len - sizeof(nokey_name.bytes), 388 nokey_name.sha256); 389 size = FSCRYPT_NOKEY_NAME_MAX; 390 } 391 oname->len = fscrypt_base64url_encode((const u8 *)&nokey_name, size, 392 oname->name); 393 return 0; 394 } 395 EXPORT_SYMBOL(fscrypt_fname_disk_to_usr); 396 397 /** 398 * fscrypt_setup_filename() - prepare to search a possibly encrypted directory 399 * @dir: the directory that will be searched 400 * @iname: the user-provided filename being searched for 401 * @lookup: 1 if we're allowed to proceed without the key because it's 402 * ->lookup() or we're finding the dir_entry for deletion; 0 if we cannot 403 * proceed without the key because we're going to create the dir_entry. 404 * @fname: the filename information to be filled in 405 * 406 * Given a user-provided filename @iname, this function sets @fname->disk_name 407 * to the name that would be stored in the on-disk directory entry, if possible. 408 * If the directory is unencrypted this is simply @iname. Else, if we have the 409 * directory's encryption key, then @iname is the plaintext, so we encrypt it to 410 * get the disk_name. 411 * 412 * Else, for keyless @lookup operations, @iname should be a no-key name, so we 413 * decode it to get the struct fscrypt_nokey_name. Non-@lookup operations will 414 * be impossible in this case, so we fail them with ENOKEY. 415 * 416 * If successful, fscrypt_free_filename() must be called later to clean up. 417 * 418 * Return: 0 on success, -errno on failure 419 */ 420 int fscrypt_setup_filename(struct inode *dir, const struct qstr *iname, 421 int lookup, struct fscrypt_name *fname) 422 { 423 struct fscrypt_nokey_name *nokey_name; 424 int ret; 425 426 memset(fname, 0, sizeof(struct fscrypt_name)); 427 fname->usr_fname = iname; 428 429 if (!IS_ENCRYPTED(dir) || fscrypt_is_dot_dotdot(iname)) { 430 fname->disk_name.name = (unsigned char *)iname->name; 431 fname->disk_name.len = iname->len; 432 return 0; 433 } 434 ret = fscrypt_get_encryption_info(dir, lookup); 435 if (ret) 436 return ret; 437 438 if (fscrypt_has_encryption_key(dir)) { 439 if (!fscrypt_fname_encrypted_size(dir, iname->len, NAME_MAX, 440 &fname->crypto_buf.len)) 441 return -ENAMETOOLONG; 442 fname->crypto_buf.name = kmalloc(fname->crypto_buf.len, 443 GFP_NOFS); 444 if (!fname->crypto_buf.name) 445 return -ENOMEM; 446 447 ret = fscrypt_fname_encrypt(dir, iname, fname->crypto_buf.name, 448 fname->crypto_buf.len); 449 if (ret) 450 goto errout; 451 fname->disk_name.name = fname->crypto_buf.name; 452 fname->disk_name.len = fname->crypto_buf.len; 453 return 0; 454 } 455 if (!lookup) 456 return -ENOKEY; 457 fname->is_nokey_name = true; 458 459 /* 460 * We don't have the key and we are doing a lookup; decode the 461 * user-supplied name 462 */ 463 464 if (iname->len > FSCRYPT_NOKEY_NAME_MAX_ENCODED) 465 return -ENOENT; 466 467 fname->crypto_buf.name = kmalloc(FSCRYPT_NOKEY_NAME_MAX, GFP_KERNEL); 468 if (fname->crypto_buf.name == NULL) 469 return -ENOMEM; 470 471 ret = fscrypt_base64url_decode(iname->name, iname->len, 472 fname->crypto_buf.name); 473 if (ret < (int)offsetof(struct fscrypt_nokey_name, bytes[1]) || 474 (ret > offsetof(struct fscrypt_nokey_name, sha256) && 475 ret != FSCRYPT_NOKEY_NAME_MAX)) { 476 ret = -ENOENT; 477 goto errout; 478 } 479 fname->crypto_buf.len = ret; 480 481 nokey_name = (void *)fname->crypto_buf.name; 482 fname->hash = nokey_name->dirhash[0]; 483 fname->minor_hash = nokey_name->dirhash[1]; 484 if (ret != FSCRYPT_NOKEY_NAME_MAX) { 485 /* The full ciphertext filename is available. */ 486 fname->disk_name.name = nokey_name->bytes; 487 fname->disk_name.len = 488 ret - offsetof(struct fscrypt_nokey_name, bytes); 489 } 490 return 0; 491 492 errout: 493 kfree(fname->crypto_buf.name); 494 return ret; 495 } 496 EXPORT_SYMBOL(fscrypt_setup_filename); 497 498 /** 499 * fscrypt_match_name() - test whether the given name matches a directory entry 500 * @fname: the name being searched for 501 * @de_name: the name from the directory entry 502 * @de_name_len: the length of @de_name in bytes 503 * 504 * Normally @fname->disk_name will be set, and in that case we simply compare 505 * that to the name stored in the directory entry. The only exception is that 506 * if we don't have the key for an encrypted directory and the name we're 507 * looking for is very long, then we won't have the full disk_name and instead 508 * we'll need to match against a fscrypt_nokey_name that includes a strong hash. 509 * 510 * Return: %true if the name matches, otherwise %false. 511 */ 512 bool fscrypt_match_name(const struct fscrypt_name *fname, 513 const u8 *de_name, u32 de_name_len) 514 { 515 const struct fscrypt_nokey_name *nokey_name = 516 (const void *)fname->crypto_buf.name; 517 u8 digest[SHA256_DIGEST_SIZE]; 518 519 if (likely(fname->disk_name.name)) { 520 if (de_name_len != fname->disk_name.len) 521 return false; 522 return !memcmp(de_name, fname->disk_name.name, de_name_len); 523 } 524 if (de_name_len <= sizeof(nokey_name->bytes)) 525 return false; 526 if (memcmp(de_name, nokey_name->bytes, sizeof(nokey_name->bytes))) 527 return false; 528 sha256(&de_name[sizeof(nokey_name->bytes)], 529 de_name_len - sizeof(nokey_name->bytes), digest); 530 return !memcmp(digest, nokey_name->sha256, sizeof(digest)); 531 } 532 EXPORT_SYMBOL_GPL(fscrypt_match_name); 533 534 /** 535 * fscrypt_fname_siphash() - calculate the SipHash of a filename 536 * @dir: the parent directory 537 * @name: the filename to calculate the SipHash of 538 * 539 * Given a plaintext filename @name and a directory @dir which uses SipHash as 540 * its dirhash method and has had its fscrypt key set up, this function 541 * calculates the SipHash of that name using the directory's secret dirhash key. 542 * 543 * Return: the SipHash of @name using the hash key of @dir 544 */ 545 u64 fscrypt_fname_siphash(const struct inode *dir, const struct qstr *name) 546 { 547 const struct fscrypt_inode_info *ci = fscrypt_get_inode_info_raw(dir); 548 549 WARN_ON_ONCE(!ci->ci_dirhash_key_initialized); 550 551 return siphash(name->name, name->len, &ci->ci_dirhash_key); 552 } 553 EXPORT_SYMBOL_GPL(fscrypt_fname_siphash); 554 555 /* 556 * Validate dentries in encrypted directories to make sure we aren't potentially 557 * caching stale dentries after a key has been added. 558 */ 559 int fscrypt_d_revalidate(struct inode *dir, const struct qstr *name, 560 struct dentry *dentry, unsigned int flags) 561 { 562 int err; 563 564 /* 565 * Plaintext names are always valid, since fscrypt doesn't support 566 * reverting to no-key names without evicting the directory's inode 567 * -- which implies eviction of the dentries in the directory. 568 */ 569 if (!(dentry->d_flags & DCACHE_NOKEY_NAME)) 570 return 1; 571 572 /* 573 * No-key name; valid if the directory's key is still unavailable. 574 * 575 * Note in RCU mode we have to bail if we get here - 576 * fscrypt_get_encryption_info() may block. 577 */ 578 579 if (flags & LOOKUP_RCU) 580 return -ECHILD; 581 582 /* 583 * Pass allow_unsupported=true, so that files with an unsupported 584 * encryption policy can be deleted. 585 */ 586 err = fscrypt_get_encryption_info(dir, true); 587 if (err < 0) 588 return err; 589 590 return !fscrypt_has_encryption_key(dir); 591 } 592 EXPORT_SYMBOL_GPL(fscrypt_d_revalidate); 593