1 /* 2 * namei.c - NTFS kernel directory inode operations. Part of the Linux-NTFS 3 * project. 4 * 5 * Copyright (c) 2001-2006 Anton Altaparmakov 6 * 7 * This program/include file is free software; you can redistribute it and/or 8 * modify it under the terms of the GNU General Public License as published 9 * by the Free Software Foundation; either version 2 of the License, or 10 * (at your option) any later version. 11 * 12 * This program/include file is distributed in the hope that it will be 13 * useful, but WITHOUT ANY WARRANTY; without even the implied warranty 14 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15 * GNU General Public License for more details. 16 * 17 * You should have received a copy of the GNU General Public License 18 * along with this program (in the main directory of the Linux-NTFS 19 * distribution in the file COPYING); if not, write to the Free Software 20 * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 21 */ 22 23 #include <linux/dcache.h> 24 #include <linux/security.h> 25 26 #include "attrib.h" 27 #include "debug.h" 28 #include "dir.h" 29 #include "mft.h" 30 #include "ntfs.h" 31 32 /** 33 * ntfs_lookup - find the inode represented by a dentry in a directory inode 34 * @dir_ino: directory inode in which to look for the inode 35 * @dent: dentry representing the inode to look for 36 * @nd: lookup nameidata 37 * 38 * In short, ntfs_lookup() looks for the inode represented by the dentry @dent 39 * in the directory inode @dir_ino and if found attaches the inode to the 40 * dentry @dent. 41 * 42 * In more detail, the dentry @dent specifies which inode to look for by 43 * supplying the name of the inode in @dent->d_name.name. ntfs_lookup() 44 * converts the name to Unicode and walks the contents of the directory inode 45 * @dir_ino looking for the converted Unicode name. If the name is found in the 46 * directory, the corresponding inode is loaded by calling ntfs_iget() on its 47 * inode number and the inode is associated with the dentry @dent via a call to 48 * d_splice_alias(). 49 * 50 * If the name is not found in the directory, a NULL inode is inserted into the 51 * dentry @dent via a call to d_add(). The dentry is then termed a negative 52 * dentry. 53 * 54 * Only if an actual error occurs, do we return an error via ERR_PTR(). 55 * 56 * In order to handle the case insensitivity issues of NTFS with regards to the 57 * dcache and the dcache requiring only one dentry per directory, we deal with 58 * dentry aliases that only differ in case in ->ntfs_lookup() while maintaining 59 * a case sensitive dcache. This means that we get the full benefit of dcache 60 * speed when the file/directory is looked up with the same case as returned by 61 * ->ntfs_readdir() but that a lookup for any other case (or for the short file 62 * name) will not find anything in dcache and will enter ->ntfs_lookup() 63 * instead, where we search the directory for a fully matching file name 64 * (including case) and if that is not found, we search for a file name that 65 * matches with different case and if that has non-POSIX semantics we return 66 * that. We actually do only one search (case sensitive) and keep tabs on 67 * whether we have found a case insensitive match in the process. 68 * 69 * To simplify matters for us, we do not treat the short vs long filenames as 70 * two hard links but instead if the lookup matches a short filename, we 71 * return the dentry for the corresponding long filename instead. 72 * 73 * There are three cases we need to distinguish here: 74 * 75 * 1) @dent perfectly matches (i.e. including case) a directory entry with a 76 * file name in the WIN32 or POSIX namespaces. In this case 77 * ntfs_lookup_inode_by_name() will return with name set to NULL and we 78 * just d_splice_alias() @dent. 79 * 2) @dent matches (not including case) a directory entry with a file name in 80 * the WIN32 namespace. In this case ntfs_lookup_inode_by_name() will return 81 * with name set to point to a kmalloc()ed ntfs_name structure containing 82 * the properly cased little endian Unicode name. We convert the name to the 83 * current NLS code page, search if a dentry with this name already exists 84 * and if so return that instead of @dent. At this point things are 85 * complicated by the possibility of 'disconnected' dentries due to NFS 86 * which we deal with appropriately (see the code comments). The VFS will 87 * then destroy the old @dent and use the one we returned. If a dentry is 88 * not found, we allocate a new one, d_splice_alias() it, and return it as 89 * above. 90 * 3) @dent matches either perfectly or not (i.e. we don't care about case) a 91 * directory entry with a file name in the DOS namespace. In this case 92 * ntfs_lookup_inode_by_name() will return with name set to point to a 93 * kmalloc()ed ntfs_name structure containing the mft reference (cpu endian) 94 * of the inode. We use the mft reference to read the inode and to find the 95 * file name in the WIN32 namespace corresponding to the matched short file 96 * name. We then convert the name to the current NLS code page, and proceed 97 * searching for a dentry with this name, etc, as in case 2), above. 98 * 99 * Locking: Caller must hold i_mutex on the directory. 100 */ 101 static struct dentry *ntfs_lookup(struct inode *dir_ino, struct dentry *dent, 102 struct nameidata *nd) 103 { 104 ntfs_volume *vol = NTFS_SB(dir_ino->i_sb); 105 struct inode *dent_inode; 106 ntfschar *uname; 107 ntfs_name *name = NULL; 108 MFT_REF mref; 109 unsigned long dent_ino; 110 int uname_len; 111 112 ntfs_debug("Looking up %s in directory inode 0x%lx.", 113 dent->d_name.name, dir_ino->i_ino); 114 /* Convert the name of the dentry to Unicode. */ 115 uname_len = ntfs_nlstoucs(vol, dent->d_name.name, dent->d_name.len, 116 &uname); 117 if (uname_len < 0) { 118 if (uname_len != -ENAMETOOLONG) 119 ntfs_error(vol->sb, "Failed to convert name to " 120 "Unicode."); 121 return ERR_PTR(uname_len); 122 } 123 mref = ntfs_lookup_inode_by_name(NTFS_I(dir_ino), uname, uname_len, 124 &name); 125 kmem_cache_free(ntfs_name_cache, uname); 126 if (!IS_ERR_MREF(mref)) { 127 dent_ino = MREF(mref); 128 ntfs_debug("Found inode 0x%lx. Calling ntfs_iget.", dent_ino); 129 dent_inode = ntfs_iget(vol->sb, dent_ino); 130 if (likely(!IS_ERR(dent_inode))) { 131 /* Consistency check. */ 132 if (is_bad_inode(dent_inode) || MSEQNO(mref) == 133 NTFS_I(dent_inode)->seq_no || 134 dent_ino == FILE_MFT) { 135 /* Perfect WIN32/POSIX match. -- Case 1. */ 136 if (!name) { 137 ntfs_debug("Done. (Case 1.)"); 138 return d_splice_alias(dent_inode, dent); 139 } 140 /* 141 * We are too indented. Handle imperfect 142 * matches and short file names further below. 143 */ 144 goto handle_name; 145 } 146 ntfs_error(vol->sb, "Found stale reference to inode " 147 "0x%lx (reference sequence number = " 148 "0x%x, inode sequence number = 0x%x), " 149 "returning -EIO. Run chkdsk.", 150 dent_ino, MSEQNO(mref), 151 NTFS_I(dent_inode)->seq_no); 152 iput(dent_inode); 153 dent_inode = ERR_PTR(-EIO); 154 } else 155 ntfs_error(vol->sb, "ntfs_iget(0x%lx) failed with " 156 "error code %li.", dent_ino, 157 PTR_ERR(dent_inode)); 158 kfree(name); 159 /* Return the error code. */ 160 return (struct dentry *)dent_inode; 161 } 162 /* It is guaranteed that @name is no longer allocated at this point. */ 163 if (MREF_ERR(mref) == -ENOENT) { 164 ntfs_debug("Entry was not found, adding negative dentry."); 165 /* The dcache will handle negative entries. */ 166 d_add(dent, NULL); 167 ntfs_debug("Done."); 168 return NULL; 169 } 170 ntfs_error(vol->sb, "ntfs_lookup_ino_by_name() failed with error " 171 "code %i.", -MREF_ERR(mref)); 172 return ERR_PTR(MREF_ERR(mref)); 173 // TODO: Consider moving this lot to a separate function! (AIA) 174 handle_name: 175 { 176 struct dentry *real_dent, *new_dent; 177 MFT_RECORD *m; 178 ntfs_attr_search_ctx *ctx; 179 ntfs_inode *ni = NTFS_I(dent_inode); 180 int err; 181 struct qstr nls_name; 182 183 nls_name.name = NULL; 184 if (name->type != FILE_NAME_DOS) { /* Case 2. */ 185 ntfs_debug("Case 2."); 186 nls_name.len = (unsigned)ntfs_ucstonls(vol, 187 (ntfschar*)&name->name, name->len, 188 (unsigned char**)&nls_name.name, 0); 189 kfree(name); 190 } else /* if (name->type == FILE_NAME_DOS) */ { /* Case 3. */ 191 FILE_NAME_ATTR *fn; 192 193 ntfs_debug("Case 3."); 194 kfree(name); 195 196 /* Find the WIN32 name corresponding to the matched DOS name. */ 197 ni = NTFS_I(dent_inode); 198 m = map_mft_record(ni); 199 if (IS_ERR(m)) { 200 err = PTR_ERR(m); 201 m = NULL; 202 ctx = NULL; 203 goto err_out; 204 } 205 ctx = ntfs_attr_get_search_ctx(ni, m); 206 if (unlikely(!ctx)) { 207 err = -ENOMEM; 208 goto err_out; 209 } 210 do { 211 ATTR_RECORD *a; 212 u32 val_len; 213 214 err = ntfs_attr_lookup(AT_FILE_NAME, NULL, 0, 0, 0, 215 NULL, 0, ctx); 216 if (unlikely(err)) { 217 ntfs_error(vol->sb, "Inode corrupt: No WIN32 " 218 "namespace counterpart to DOS " 219 "file name. Run chkdsk."); 220 if (err == -ENOENT) 221 err = -EIO; 222 goto err_out; 223 } 224 /* Consistency checks. */ 225 a = ctx->attr; 226 if (a->non_resident || a->flags) 227 goto eio_err_out; 228 val_len = le32_to_cpu(a->data.resident.value_length); 229 if (le16_to_cpu(a->data.resident.value_offset) + 230 val_len > le32_to_cpu(a->length)) 231 goto eio_err_out; 232 fn = (FILE_NAME_ATTR*)((u8*)ctx->attr + le16_to_cpu( 233 ctx->attr->data.resident.value_offset)); 234 if ((u32)(fn->file_name_length * sizeof(ntfschar) + 235 sizeof(FILE_NAME_ATTR)) > val_len) 236 goto eio_err_out; 237 } while (fn->file_name_type != FILE_NAME_WIN32); 238 239 /* Convert the found WIN32 name to current NLS code page. */ 240 nls_name.len = (unsigned)ntfs_ucstonls(vol, 241 (ntfschar*)&fn->file_name, fn->file_name_length, 242 (unsigned char**)&nls_name.name, 0); 243 244 ntfs_attr_put_search_ctx(ctx); 245 unmap_mft_record(ni); 246 } 247 m = NULL; 248 ctx = NULL; 249 250 /* Check if a conversion error occurred. */ 251 if ((signed)nls_name.len < 0) { 252 err = (signed)nls_name.len; 253 goto err_out; 254 } 255 nls_name.hash = full_name_hash(nls_name.name, nls_name.len); 256 257 /* 258 * Note: No need for dent->d_lock lock as i_mutex is held on the 259 * parent inode. 260 */ 261 262 /* Does a dentry matching the nls_name exist already? */ 263 real_dent = d_lookup(dent->d_parent, &nls_name); 264 /* If not, create it now. */ 265 if (!real_dent) { 266 real_dent = d_alloc(dent->d_parent, &nls_name); 267 kfree(nls_name.name); 268 if (!real_dent) { 269 err = -ENOMEM; 270 goto err_out; 271 } 272 new_dent = d_splice_alias(dent_inode, real_dent); 273 if (new_dent) 274 dput(real_dent); 275 else 276 new_dent = real_dent; 277 ntfs_debug("Done. (Created new dentry.)"); 278 return new_dent; 279 } 280 kfree(nls_name.name); 281 /* Matching dentry exists, check if it is negative. */ 282 if (real_dent->d_inode) { 283 if (unlikely(real_dent->d_inode != dent_inode)) { 284 /* This can happen because bad inodes are unhashed. */ 285 BUG_ON(!is_bad_inode(dent_inode)); 286 BUG_ON(!is_bad_inode(real_dent->d_inode)); 287 } 288 /* 289 * Already have the inode and the dentry attached, decrement 290 * the reference count to balance the ntfs_iget() we did 291 * earlier on. We found the dentry using d_lookup() so it 292 * cannot be disconnected and thus we do not need to worry 293 * about any NFS/disconnectedness issues here. 294 */ 295 iput(dent_inode); 296 ntfs_debug("Done. (Already had inode and dentry.)"); 297 return real_dent; 298 } 299 /* 300 * Negative dentry: instantiate it unless the inode is a directory and 301 * has a 'disconnected' dentry (i.e. IS_ROOT and DCACHE_DISCONNECTED), 302 * in which case d_move() that in place of the found dentry. 303 */ 304 if (!S_ISDIR(dent_inode->i_mode)) { 305 /* Not a directory; everything is easy. */ 306 d_instantiate(real_dent, dent_inode); 307 ntfs_debug("Done. (Already had negative file dentry.)"); 308 return real_dent; 309 } 310 spin_lock(&dcache_lock); 311 if (list_empty(&dent_inode->i_dentry)) { 312 /* 313 * Directory without a 'disconnected' dentry; we need to do 314 * d_instantiate() by hand because it takes dcache_lock which 315 * we already hold. 316 */ 317 list_add(&real_dent->d_alias, &dent_inode->i_dentry); 318 real_dent->d_inode = dent_inode; 319 spin_unlock(&dcache_lock); 320 security_d_instantiate(real_dent, dent_inode); 321 ntfs_debug("Done. (Already had negative directory dentry.)"); 322 return real_dent; 323 } 324 /* 325 * Directory with a 'disconnected' dentry; get a reference to the 326 * 'disconnected' dentry. 327 */ 328 new_dent = list_entry(dent_inode->i_dentry.next, struct dentry, 329 d_alias); 330 dget_locked(new_dent); 331 spin_unlock(&dcache_lock); 332 /* Do security vodoo. */ 333 security_d_instantiate(real_dent, dent_inode); 334 /* Move new_dent in place of real_dent. */ 335 d_move(new_dent, real_dent); 336 /* Balance the ntfs_iget() we did above. */ 337 iput(dent_inode); 338 /* Throw away real_dent. */ 339 dput(real_dent); 340 /* Use new_dent as the actual dentry. */ 341 ntfs_debug("Done. (Already had negative, disconnected directory " 342 "dentry.)"); 343 return new_dent; 344 345 eio_err_out: 346 ntfs_error(vol->sb, "Illegal file name attribute. Run chkdsk."); 347 err = -EIO; 348 err_out: 349 if (ctx) 350 ntfs_attr_put_search_ctx(ctx); 351 if (m) 352 unmap_mft_record(ni); 353 iput(dent_inode); 354 ntfs_error(vol->sb, "Failed, returning error code %i.", err); 355 return ERR_PTR(err); 356 } 357 } 358 359 /** 360 * Inode operations for directories. 361 */ 362 const struct inode_operations ntfs_dir_inode_ops = { 363 .lookup = ntfs_lookup, /* VFS: Lookup directory. */ 364 }; 365 366 /** 367 * ntfs_get_parent - find the dentry of the parent of a given directory dentry 368 * @child_dent: dentry of the directory whose parent directory to find 369 * 370 * Find the dentry for the parent directory of the directory specified by the 371 * dentry @child_dent. This function is called from 372 * fs/exportfs/expfs.c::find_exported_dentry() which in turn is called from the 373 * default ->decode_fh() which is export_decode_fh() in the same file. 374 * 375 * The code is based on the ext3 ->get_parent() implementation found in 376 * fs/ext3/namei.c::ext3_get_parent(). 377 * 378 * Note: ntfs_get_parent() is called with @child_dent->d_inode->i_mutex down. 379 * 380 * Return the dentry of the parent directory on success or the error code on 381 * error (IS_ERR() is true). 382 */ 383 static struct dentry *ntfs_get_parent(struct dentry *child_dent) 384 { 385 struct inode *vi = child_dent->d_inode; 386 ntfs_inode *ni = NTFS_I(vi); 387 MFT_RECORD *mrec; 388 ntfs_attr_search_ctx *ctx; 389 ATTR_RECORD *attr; 390 FILE_NAME_ATTR *fn; 391 struct inode *parent_vi; 392 struct dentry *parent_dent; 393 unsigned long parent_ino; 394 int err; 395 396 ntfs_debug("Entering for inode 0x%lx.", vi->i_ino); 397 /* Get the mft record of the inode belonging to the child dentry. */ 398 mrec = map_mft_record(ni); 399 if (IS_ERR(mrec)) 400 return (struct dentry *)mrec; 401 /* Find the first file name attribute in the mft record. */ 402 ctx = ntfs_attr_get_search_ctx(ni, mrec); 403 if (unlikely(!ctx)) { 404 unmap_mft_record(ni); 405 return ERR_PTR(-ENOMEM); 406 } 407 try_next: 408 err = ntfs_attr_lookup(AT_FILE_NAME, NULL, 0, CASE_SENSITIVE, 0, NULL, 409 0, ctx); 410 if (unlikely(err)) { 411 ntfs_attr_put_search_ctx(ctx); 412 unmap_mft_record(ni); 413 if (err == -ENOENT) 414 ntfs_error(vi->i_sb, "Inode 0x%lx does not have a " 415 "file name attribute. Run chkdsk.", 416 vi->i_ino); 417 return ERR_PTR(err); 418 } 419 attr = ctx->attr; 420 if (unlikely(attr->non_resident)) 421 goto try_next; 422 fn = (FILE_NAME_ATTR *)((u8 *)attr + 423 le16_to_cpu(attr->data.resident.value_offset)); 424 if (unlikely((u8 *)fn + le32_to_cpu(attr->data.resident.value_length) > 425 (u8*)attr + le32_to_cpu(attr->length))) 426 goto try_next; 427 /* Get the inode number of the parent directory. */ 428 parent_ino = MREF_LE(fn->parent_directory); 429 /* Release the search context and the mft record of the child. */ 430 ntfs_attr_put_search_ctx(ctx); 431 unmap_mft_record(ni); 432 /* Get the inode of the parent directory. */ 433 parent_vi = ntfs_iget(vi->i_sb, parent_ino); 434 if (IS_ERR(parent_vi) || unlikely(is_bad_inode(parent_vi))) { 435 if (!IS_ERR(parent_vi)) 436 iput(parent_vi); 437 ntfs_error(vi->i_sb, "Failed to get parent directory inode " 438 "0x%lx of child inode 0x%lx.", parent_ino, 439 vi->i_ino); 440 return ERR_PTR(-EACCES); 441 } 442 /* Finally get a dentry for the parent directory and return it. */ 443 parent_dent = d_alloc_anon(parent_vi); 444 if (unlikely(!parent_dent)) { 445 iput(parent_vi); 446 return ERR_PTR(-ENOMEM); 447 } 448 ntfs_debug("Done for inode 0x%lx.", vi->i_ino); 449 return parent_dent; 450 } 451 452 /** 453 * ntfs_get_dentry - find a dentry for the inode from a file handle sub-fragment 454 * @sb: super block identifying the mounted ntfs volume 455 * @fh: the file handle sub-fragment 456 * 457 * Find a dentry for the inode given a file handle sub-fragment. This function 458 * is called from fs/exportfs/expfs.c::find_exported_dentry() which in turn is 459 * called from the default ->decode_fh() which is export_decode_fh() in the 460 * same file. The code is closely based on the default ->get_dentry() helper 461 * fs/exportfs/expfs.c::get_object(). 462 * 463 * The @fh contains two 32-bit unsigned values, the first one is the inode 464 * number and the second one is the inode generation. 465 * 466 * Return the dentry on success or the error code on error (IS_ERR() is true). 467 */ 468 static struct dentry *ntfs_get_dentry(struct super_block *sb, void *fh) 469 { 470 struct inode *vi; 471 struct dentry *dent; 472 unsigned long ino = ((u32 *)fh)[0]; 473 u32 gen = ((u32 *)fh)[1]; 474 475 ntfs_debug("Entering for inode 0x%lx, generation 0x%x.", ino, gen); 476 vi = ntfs_iget(sb, ino); 477 if (IS_ERR(vi)) { 478 ntfs_error(sb, "Failed to get inode 0x%lx.", ino); 479 return (struct dentry *)vi; 480 } 481 if (unlikely(is_bad_inode(vi) || vi->i_generation != gen)) { 482 /* We didn't find the right inode. */ 483 ntfs_error(sb, "Inode 0x%lx, bad count: %d %d or version 0x%x " 484 "0x%x.", vi->i_ino, vi->i_nlink, 485 atomic_read(&vi->i_count), vi->i_generation, 486 gen); 487 iput(vi); 488 return ERR_PTR(-ESTALE); 489 } 490 /* Now find a dentry. If possible, get a well-connected one. */ 491 dent = d_alloc_anon(vi); 492 if (unlikely(!dent)) { 493 iput(vi); 494 return ERR_PTR(-ENOMEM); 495 } 496 ntfs_debug("Done for inode 0x%lx, generation 0x%x.", ino, gen); 497 return dent; 498 } 499 500 /** 501 * Export operations allowing NFS exporting of mounted NTFS partitions. 502 * 503 * We use the default ->decode_fh() and ->encode_fh() for now. Note that they 504 * use 32 bits to store the inode number which is an unsigned long so on 64-bit 505 * architectures is usually 64 bits so it would all fail horribly on huge 506 * volumes. I guess we need to define our own encode and decode fh functions 507 * that store 64-bit inode numbers at some point but for now we will ignore the 508 * problem... 509 * 510 * We also use the default ->get_name() helper (used by ->decode_fh() via 511 * fs/exportfs/expfs.c::find_exported_dentry()) as that is completely fs 512 * independent. 513 * 514 * The default ->get_parent() just returns -EACCES so we have to provide our 515 * own and the default ->get_dentry() is incompatible with NTFS due to not 516 * allowing the inode number 0 which is used in NTFS for the system file $MFT 517 * and due to using iget() whereas NTFS needs ntfs_iget(). 518 */ 519 struct export_operations ntfs_export_ops = { 520 .get_parent = ntfs_get_parent, /* Find the parent of a given 521 directory. */ 522 .get_dentry = ntfs_get_dentry, /* Find a dentry for the inode 523 given a file handle 524 sub-fragment. */ 525 }; 526