1 /* 2 * namei.c - NTFS kernel directory inode operations. Part of the Linux-NTFS 3 * project. 4 * 5 * Copyright (c) 2001-2004 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_sem 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 ntfs_error(vol->sb, "Failed to convert name to Unicode."); 119 return ERR_PTR(uname_len); 120 } 121 mref = ntfs_lookup_inode_by_name(NTFS_I(dir_ino), uname, uname_len, 122 &name); 123 kmem_cache_free(ntfs_name_cache, uname); 124 if (!IS_ERR_MREF(mref)) { 125 dent_ino = MREF(mref); 126 ntfs_debug("Found inode 0x%lx. Calling ntfs_iget.", dent_ino); 127 dent_inode = ntfs_iget(vol->sb, dent_ino); 128 if (likely(!IS_ERR(dent_inode))) { 129 /* Consistency check. */ 130 if (is_bad_inode(dent_inode) || MSEQNO(mref) == 131 NTFS_I(dent_inode)->seq_no || 132 dent_ino == FILE_MFT) { 133 /* Perfect WIN32/POSIX match. -- Case 1. */ 134 if (!name) { 135 ntfs_debug("Done. (Case 1.)"); 136 return d_splice_alias(dent_inode, dent); 137 } 138 /* 139 * We are too indented. Handle imperfect 140 * matches and short file names further below. 141 */ 142 goto handle_name; 143 } 144 ntfs_error(vol->sb, "Found stale reference to inode " 145 "0x%lx (reference sequence number = " 146 "0x%x, inode sequence number = 0x%x), " 147 "returning -EIO. Run chkdsk.", 148 dent_ino, MSEQNO(mref), 149 NTFS_I(dent_inode)->seq_no); 150 iput(dent_inode); 151 dent_inode = ERR_PTR(-EIO); 152 } else 153 ntfs_error(vol->sb, "ntfs_iget(0x%lx) failed with " 154 "error code %li.", dent_ino, 155 PTR_ERR(dent_inode)); 156 kfree(name); 157 /* Return the error code. */ 158 return (struct dentry *)dent_inode; 159 } 160 /* It is guaranteed that name is no longer allocated at this point. */ 161 if (MREF_ERR(mref) == -ENOENT) { 162 ntfs_debug("Entry was not found, adding negative dentry."); 163 /* The dcache will handle negative entries. */ 164 d_add(dent, NULL); 165 ntfs_debug("Done."); 166 return NULL; 167 } 168 ntfs_error(vol->sb, "ntfs_lookup_ino_by_name() failed with error " 169 "code %i.", -MREF_ERR(mref)); 170 return ERR_PTR(MREF_ERR(mref)); 171 172 // TODO: Consider moving this lot to a separate function! (AIA) 173 handle_name: 174 { 175 struct dentry *real_dent, *new_dent; 176 MFT_RECORD *m; 177 ntfs_attr_search_ctx *ctx; 178 ntfs_inode *ni = NTFS_I(dent_inode); 179 int err; 180 struct qstr nls_name; 181 182 nls_name.name = NULL; 183 if (name->type != FILE_NAME_DOS) { /* Case 2. */ 184 ntfs_debug("Case 2."); 185 nls_name.len = (unsigned)ntfs_ucstonls(vol, 186 (ntfschar*)&name->name, name->len, 187 (unsigned char**)&nls_name.name, 0); 188 kfree(name); 189 } else /* if (name->type == FILE_NAME_DOS) */ { /* Case 3. */ 190 FILE_NAME_ATTR *fn; 191 192 ntfs_debug("Case 3."); 193 kfree(name); 194 195 /* Find the WIN32 name corresponding to the matched DOS name. */ 196 ni = NTFS_I(dent_inode); 197 m = map_mft_record(ni); 198 if (IS_ERR(m)) { 199 err = PTR_ERR(m); 200 m = NULL; 201 ctx = NULL; 202 goto err_out; 203 } 204 ctx = ntfs_attr_get_search_ctx(ni, m); 205 if (unlikely(!ctx)) { 206 err = -ENOMEM; 207 goto err_out; 208 } 209 do { 210 ATTR_RECORD *a; 211 u32 val_len; 212 213 err = ntfs_attr_lookup(AT_FILE_NAME, NULL, 0, 0, 0, 214 NULL, 0, ctx); 215 if (unlikely(err)) { 216 ntfs_error(vol->sb, "Inode corrupt: No WIN32 " 217 "namespace counterpart to DOS " 218 "file name. Run chkdsk."); 219 if (err == -ENOENT) 220 err = -EIO; 221 goto err_out; 222 } 223 /* Consistency checks. */ 224 a = ctx->attr; 225 if (a->non_resident || a->flags) 226 goto eio_err_out; 227 val_len = le32_to_cpu(a->data.resident.value_length); 228 if (le16_to_cpu(a->data.resident.value_offset) + 229 val_len > le32_to_cpu(a->length)) 230 goto eio_err_out; 231 fn = (FILE_NAME_ATTR*)((u8*)ctx->attr + le16_to_cpu( 232 ctx->attr->data.resident.value_offset)); 233 if ((u32)(fn->file_name_length * sizeof(ntfschar) + 234 sizeof(FILE_NAME_ATTR)) > val_len) 235 goto eio_err_out; 236 } while (fn->file_name_type != FILE_NAME_WIN32); 237 238 /* Convert the found WIN32 name to current NLS code page. */ 239 nls_name.len = (unsigned)ntfs_ucstonls(vol, 240 (ntfschar*)&fn->file_name, fn->file_name_length, 241 (unsigned char**)&nls_name.name, 0); 242 243 ntfs_attr_put_search_ctx(ctx); 244 unmap_mft_record(ni); 245 } 246 m = NULL; 247 ctx = NULL; 248 249 /* Check if a conversion error occurred. */ 250 if ((signed)nls_name.len < 0) { 251 err = (signed)nls_name.len; 252 goto err_out; 253 } 254 nls_name.hash = full_name_hash(nls_name.name, nls_name.len); 255 256 /* 257 * Note: No need for dent->d_lock lock as i_sem is held on the 258 * parent inode. 259 */ 260 261 /* Does a dentry matching the nls_name exist already? */ 262 real_dent = d_lookup(dent->d_parent, &nls_name); 263 /* If not, create it now. */ 264 if (!real_dent) { 265 real_dent = d_alloc(dent->d_parent, &nls_name); 266 kfree(nls_name.name); 267 if (!real_dent) { 268 err = -ENOMEM; 269 goto err_out; 270 } 271 new_dent = d_splice_alias(dent_inode, real_dent); 272 if (new_dent) 273 dput(real_dent); 274 else 275 new_dent = real_dent; 276 ntfs_debug("Done. (Created new dentry.)"); 277 return new_dent; 278 } 279 kfree(nls_name.name); 280 /* Matching dentry exists, check if it is negative. */ 281 if (real_dent->d_inode) { 282 if (unlikely(real_dent->d_inode != dent_inode)) { 283 /* This can happen because bad inodes are unhashed. */ 284 BUG_ON(!is_bad_inode(dent_inode)); 285 BUG_ON(!is_bad_inode(real_dent->d_inode)); 286 } 287 /* 288 * Already have the inode and the dentry attached, decrement 289 * the reference count to balance the ntfs_iget() we did 290 * earlier on. We found the dentry using d_lookup() so it 291 * cannot be disconnected and thus we do not need to worry 292 * about any NFS/disconnectedness issues here. 293 */ 294 iput(dent_inode); 295 ntfs_debug("Done. (Already had inode and dentry.)"); 296 return real_dent; 297 } 298 /* 299 * Negative dentry: instantiate it unless the inode is a directory and 300 * has a 'disconnected' dentry (i.e. IS_ROOT and DCACHE_DISCONNECTED), 301 * in which case d_move() that in place of the found dentry. 302 */ 303 if (!S_ISDIR(dent_inode->i_mode)) { 304 /* Not a directory; everything is easy. */ 305 d_instantiate(real_dent, dent_inode); 306 ntfs_debug("Done. (Already had negative file dentry.)"); 307 return real_dent; 308 } 309 spin_lock(&dcache_lock); 310 if (list_empty(&dent_inode->i_dentry)) { 311 /* 312 * Directory without a 'disconnected' dentry; we need to do 313 * d_instantiate() by hand because it takes dcache_lock which 314 * we already hold. 315 */ 316 list_add(&real_dent->d_alias, &dent_inode->i_dentry); 317 real_dent->d_inode = dent_inode; 318 spin_unlock(&dcache_lock); 319 security_d_instantiate(real_dent, dent_inode); 320 ntfs_debug("Done. (Already had negative directory dentry.)"); 321 return real_dent; 322 } 323 /* 324 * Directory with a 'disconnected' dentry; get a reference to the 325 * 'disconnected' dentry. 326 */ 327 new_dent = list_entry(dent_inode->i_dentry.next, struct dentry, 328 d_alias); 329 dget_locked(new_dent); 330 spin_unlock(&dcache_lock); 331 /* Do security vodoo. */ 332 security_d_instantiate(real_dent, dent_inode); 333 /* Move new_dent in place of real_dent. */ 334 d_move(new_dent, real_dent); 335 /* Balance the ntfs_iget() we did above. */ 336 iput(dent_inode); 337 /* Throw away real_dent. */ 338 dput(real_dent); 339 /* Use new_dent as the actual dentry. */ 340 ntfs_debug("Done. (Already had negative, disconnected directory " 341 "dentry.)"); 342 return new_dent; 343 344 eio_err_out: 345 ntfs_error(vol->sb, "Illegal file name attribute. Run chkdsk."); 346 err = -EIO; 347 err_out: 348 if (ctx) 349 ntfs_attr_put_search_ctx(ctx); 350 if (m) 351 unmap_mft_record(ni); 352 iput(dent_inode); 353 ntfs_error(vol->sb, "Failed, returning error code %i.", err); 354 return ERR_PTR(err); 355 } 356 } 357 358 /** 359 * Inode operations for directories. 360 */ 361 struct inode_operations ntfs_dir_inode_ops = { 362 .lookup = ntfs_lookup, /* VFS: Lookup directory. */ 363 }; 364 365 /** 366 * ntfs_get_parent - find the dentry of the parent of a given directory dentry 367 * @child_dent: dentry of the directory whose parent directory to find 368 * 369 * Find the dentry for the parent directory of the directory specified by the 370 * dentry @child_dent. This function is called from 371 * fs/exportfs/expfs.c::find_exported_dentry() which in turn is called from the 372 * default ->decode_fh() which is export_decode_fh() in the same file. 373 * 374 * The code is based on the ext3 ->get_parent() implementation found in 375 * fs/ext3/namei.c::ext3_get_parent(). 376 * 377 * Note: ntfs_get_parent() is called with @child_dent->d_inode->i_sem down. 378 * 379 * Return the dentry of the parent directory on success or the error code on 380 * error (IS_ERR() is true). 381 */ 382 static struct dentry *ntfs_get_parent(struct dentry *child_dent) 383 { 384 struct inode *vi = child_dent->d_inode; 385 ntfs_inode *ni = NTFS_I(vi); 386 MFT_RECORD *mrec; 387 ntfs_attr_search_ctx *ctx; 388 ATTR_RECORD *attr; 389 FILE_NAME_ATTR *fn; 390 struct inode *parent_vi; 391 struct dentry *parent_dent; 392 unsigned long parent_ino; 393 int err; 394 395 ntfs_debug("Entering for inode 0x%lx.", vi->i_ino); 396 /* Get the mft record of the inode belonging to the child dentry. */ 397 mrec = map_mft_record(ni); 398 if (IS_ERR(mrec)) 399 return (struct dentry *)mrec; 400 /* Find the first file name attribute in the mft record. */ 401 ctx = ntfs_attr_get_search_ctx(ni, mrec); 402 if (unlikely(!ctx)) { 403 unmap_mft_record(ni); 404 return ERR_PTR(-ENOMEM); 405 } 406 try_next: 407 err = ntfs_attr_lookup(AT_FILE_NAME, NULL, 0, CASE_SENSITIVE, 0, NULL, 408 0, ctx); 409 if (unlikely(err)) { 410 ntfs_attr_put_search_ctx(ctx); 411 unmap_mft_record(ni); 412 if (err == -ENOENT) 413 ntfs_error(vi->i_sb, "Inode 0x%lx does not have a " 414 "file name attribute. Run chkdsk.", 415 vi->i_ino); 416 return ERR_PTR(err); 417 } 418 attr = ctx->attr; 419 if (unlikely(attr->non_resident)) 420 goto try_next; 421 fn = (FILE_NAME_ATTR *)((u8 *)attr + 422 le16_to_cpu(attr->data.resident.value_offset)); 423 if (unlikely((u8 *)fn + le32_to_cpu(attr->data.resident.value_length) > 424 (u8*)attr + le32_to_cpu(attr->length))) 425 goto try_next; 426 /* Get the inode number of the parent directory. */ 427 parent_ino = MREF_LE(fn->parent_directory); 428 /* Release the search context and the mft record of the child. */ 429 ntfs_attr_put_search_ctx(ctx); 430 unmap_mft_record(ni); 431 /* Get the inode of the parent directory. */ 432 parent_vi = ntfs_iget(vi->i_sb, parent_ino); 433 if (IS_ERR(parent_vi) || unlikely(is_bad_inode(parent_vi))) { 434 if (!IS_ERR(parent_vi)) 435 iput(parent_vi); 436 ntfs_error(vi->i_sb, "Failed to get parent directory inode " 437 "0x%lx of child inode 0x%lx.", parent_ino, 438 vi->i_ino); 439 return ERR_PTR(-EACCES); 440 } 441 /* Finally get a dentry for the parent directory and return it. */ 442 parent_dent = d_alloc_anon(parent_vi); 443 if (unlikely(!parent_dent)) { 444 iput(parent_vi); 445 return ERR_PTR(-ENOMEM); 446 } 447 ntfs_debug("Done for inode 0x%lx.", vi->i_ino); 448 return parent_dent; 449 } 450 451 /** 452 * ntfs_get_dentry - find a dentry for the inode from a file handle sub-fragment 453 * @sb: super block identifying the mounted ntfs volume 454 * @fh: the file handle sub-fragment 455 * 456 * Find a dentry for the inode given a file handle sub-fragment. This function 457 * is called from fs/exportfs/expfs.c::find_exported_dentry() which in turn is 458 * called from the default ->decode_fh() which is export_decode_fh() in the 459 * same file. The code is closely based on the default ->get_dentry() helper 460 * fs/exportfs/expfs.c::get_object(). 461 * 462 * The @fh contains two 32-bit unsigned values, the first one is the inode 463 * number and the second one is the inode generation. 464 * 465 * Return the dentry on success or the error code on error (IS_ERR() is true). 466 */ 467 static struct dentry *ntfs_get_dentry(struct super_block *sb, void *fh) 468 { 469 struct inode *vi; 470 struct dentry *dent; 471 unsigned long ino = ((u32 *)fh)[0]; 472 u32 gen = ((u32 *)fh)[1]; 473 474 ntfs_debug("Entering for inode 0x%lx, generation 0x%x.", ino, gen); 475 vi = ntfs_iget(sb, ino); 476 if (IS_ERR(vi)) { 477 ntfs_error(sb, "Failed to get inode 0x%lx.", ino); 478 return (struct dentry *)vi; 479 } 480 if (unlikely(is_bad_inode(vi) || vi->i_generation != gen)) { 481 /* We didn't find the right inode. */ 482 ntfs_error(sb, "Inode 0x%lx, bad count: %d %d or version 0x%x " 483 "0x%x.", vi->i_ino, vi->i_nlink, 484 atomic_read(&vi->i_count), vi->i_generation, 485 gen); 486 iput(vi); 487 return ERR_PTR(-ESTALE); 488 } 489 /* Now find a dentry. If possible, get a well-connected one. */ 490 dent = d_alloc_anon(vi); 491 if (unlikely(!dent)) { 492 iput(vi); 493 return ERR_PTR(-ENOMEM); 494 } 495 ntfs_debug("Done for inode 0x%lx, generation 0x%x.", ino, gen); 496 return dent; 497 } 498 499 /** 500 * Export operations allowing NFS exporting of mounted NTFS partitions. 501 * 502 * We use the default ->decode_fh() and ->encode_fh() for now. Note that they 503 * use 32 bits to store the inode number which is an unsigned long so on 64-bit 504 * architectures is usually 64 bits so it would all fail horribly on huge 505 * volumes. I guess we need to define our own encode and decode fh functions 506 * that store 64-bit inode numbers at some point but for now we will ignore the 507 * problem... 508 * 509 * We also use the default ->get_name() helper (used by ->decode_fh() via 510 * fs/exportfs/expfs.c::find_exported_dentry()) as that is completely fs 511 * independent. 512 * 513 * The default ->get_parent() just returns -EACCES so we have to provide our 514 * own and the default ->get_dentry() is incompatible with NTFS due to not 515 * allowing the inode number 0 which is used in NTFS for the system file $MFT 516 * and due to using iget() whereas NTFS needs ntfs_iget(). 517 */ 518 struct export_operations ntfs_export_ops = { 519 .get_parent = ntfs_get_parent, /* Find the parent of a given 520 directory. */ 521 .get_dentry = ntfs_get_dentry, /* Find a dentry for the inode 522 given a file handle 523 sub-fragment. */ 524 }; 525