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/exportfs.h> 25 #include <linux/security.h> 26 27 #include "attrib.h" 28 #include "debug.h" 29 #include "dir.h" 30 #include "mft.h" 31 #include "ntfs.h" 32 33 /** 34 * ntfs_lookup - find the inode represented by a dentry in a directory inode 35 * @dir_ino: directory inode in which to look for the inode 36 * @dent: dentry representing the inode to look for 37 * @nd: lookup nameidata 38 * 39 * In short, ntfs_lookup() looks for the inode represented by the dentry @dent 40 * in the directory inode @dir_ino and if found attaches the inode to the 41 * dentry @dent. 42 * 43 * In more detail, the dentry @dent specifies which inode to look for by 44 * supplying the name of the inode in @dent->d_name.name. ntfs_lookup() 45 * converts the name to Unicode and walks the contents of the directory inode 46 * @dir_ino looking for the converted Unicode name. If the name is found in the 47 * directory, the corresponding inode is loaded by calling ntfs_iget() on its 48 * inode number and the inode is associated with the dentry @dent via a call to 49 * d_splice_alias(). 50 * 51 * If the name is not found in the directory, a NULL inode is inserted into the 52 * dentry @dent via a call to d_add(). The dentry is then termed a negative 53 * dentry. 54 * 55 * Only if an actual error occurs, do we return an error via ERR_PTR(). 56 * 57 * In order to handle the case insensitivity issues of NTFS with regards to the 58 * dcache and the dcache requiring only one dentry per directory, we deal with 59 * dentry aliases that only differ in case in ->ntfs_lookup() while maintaining 60 * a case sensitive dcache. This means that we get the full benefit of dcache 61 * speed when the file/directory is looked up with the same case as returned by 62 * ->ntfs_readdir() but that a lookup for any other case (or for the short file 63 * name) will not find anything in dcache and will enter ->ntfs_lookup() 64 * instead, where we search the directory for a fully matching file name 65 * (including case) and if that is not found, we search for a file name that 66 * matches with different case and if that has non-POSIX semantics we return 67 * that. We actually do only one search (case sensitive) and keep tabs on 68 * whether we have found a case insensitive match in the process. 69 * 70 * To simplify matters for us, we do not treat the short vs long filenames as 71 * two hard links but instead if the lookup matches a short filename, we 72 * return the dentry for the corresponding long filename instead. 73 * 74 * There are three cases we need to distinguish here: 75 * 76 * 1) @dent perfectly matches (i.e. including case) a directory entry with a 77 * file name in the WIN32 or POSIX namespaces. In this case 78 * ntfs_lookup_inode_by_name() will return with name set to NULL and we 79 * just d_splice_alias() @dent. 80 * 2) @dent matches (not including case) a directory entry with a file name in 81 * the WIN32 namespace. In this case ntfs_lookup_inode_by_name() will return 82 * with name set to point to a kmalloc()ed ntfs_name structure containing 83 * the properly cased little endian Unicode name. We convert the name to the 84 * current NLS code page, search if a dentry with this name already exists 85 * and if so return that instead of @dent. At this point things are 86 * complicated by the possibility of 'disconnected' dentries due to NFS 87 * which we deal with appropriately (see the code comments). The VFS will 88 * then destroy the old @dent and use the one we returned. If a dentry is 89 * not found, we allocate a new one, d_splice_alias() it, and return it as 90 * above. 91 * 3) @dent matches either perfectly or not (i.e. we don't care about case) a 92 * directory entry with a file name in the DOS namespace. In this case 93 * ntfs_lookup_inode_by_name() will return with name set to point to a 94 * kmalloc()ed ntfs_name structure containing the mft reference (cpu endian) 95 * of the inode. We use the mft reference to read the inode and to find the 96 * file name in the WIN32 namespace corresponding to the matched short file 97 * name. We then convert the name to the current NLS code page, and proceed 98 * searching for a dentry with this name, etc, as in case 2), above. 99 * 100 * Locking: Caller must hold i_mutex on the directory. 101 */ 102 static struct dentry *ntfs_lookup(struct inode *dir_ino, struct dentry *dent, 103 struct nameidata *nd) 104 { 105 ntfs_volume *vol = NTFS_SB(dir_ino->i_sb); 106 struct inode *dent_inode; 107 ntfschar *uname; 108 ntfs_name *name = NULL; 109 MFT_REF mref; 110 unsigned long dent_ino; 111 int uname_len; 112 113 ntfs_debug("Looking up %s in directory inode 0x%lx.", 114 dent->d_name.name, dir_ino->i_ino); 115 /* Convert the name of the dentry to Unicode. */ 116 uname_len = ntfs_nlstoucs(vol, dent->d_name.name, dent->d_name.len, 117 &uname); 118 if (uname_len < 0) { 119 if (uname_len != -ENAMETOOLONG) 120 ntfs_error(vol->sb, "Failed to convert name to " 121 "Unicode."); 122 return ERR_PTR(uname_len); 123 } 124 mref = ntfs_lookup_inode_by_name(NTFS_I(dir_ino), uname, uname_len, 125 &name); 126 kmem_cache_free(ntfs_name_cache, uname); 127 if (!IS_ERR_MREF(mref)) { 128 dent_ino = MREF(mref); 129 ntfs_debug("Found inode 0x%lx. Calling ntfs_iget.", dent_ino); 130 dent_inode = ntfs_iget(vol->sb, dent_ino); 131 if (likely(!IS_ERR(dent_inode))) { 132 /* Consistency check. */ 133 if (is_bad_inode(dent_inode) || MSEQNO(mref) == 134 NTFS_I(dent_inode)->seq_no || 135 dent_ino == FILE_MFT) { 136 /* Perfect WIN32/POSIX match. -- Case 1. */ 137 if (!name) { 138 ntfs_debug("Done. (Case 1.)"); 139 return d_splice_alias(dent_inode, dent); 140 } 141 /* 142 * We are too indented. Handle imperfect 143 * matches and short file names further below. 144 */ 145 goto handle_name; 146 } 147 ntfs_error(vol->sb, "Found stale reference to inode " 148 "0x%lx (reference sequence number = " 149 "0x%x, inode sequence number = 0x%x), " 150 "returning -EIO. Run chkdsk.", 151 dent_ino, MSEQNO(mref), 152 NTFS_I(dent_inode)->seq_no); 153 iput(dent_inode); 154 dent_inode = ERR_PTR(-EIO); 155 } else 156 ntfs_error(vol->sb, "ntfs_iget(0x%lx) failed with " 157 "error code %li.", dent_ino, 158 PTR_ERR(dent_inode)); 159 kfree(name); 160 /* Return the error code. */ 161 return (struct dentry *)dent_inode; 162 } 163 /* It is guaranteed that @name is no longer allocated at this point. */ 164 if (MREF_ERR(mref) == -ENOENT) { 165 ntfs_debug("Entry was not found, adding negative dentry."); 166 /* The dcache will handle negative entries. */ 167 d_add(dent, NULL); 168 ntfs_debug("Done."); 169 return NULL; 170 } 171 ntfs_error(vol->sb, "ntfs_lookup_ino_by_name() failed with error " 172 "code %i.", -MREF_ERR(mref)); 173 return ERR_PTR(MREF_ERR(mref)); 174 // TODO: Consider moving this lot to a separate function! (AIA) 175 handle_name: 176 { 177 struct dentry *real_dent, *new_dent; 178 MFT_RECORD *m; 179 ntfs_attr_search_ctx *ctx; 180 ntfs_inode *ni = NTFS_I(dent_inode); 181 int err; 182 struct qstr nls_name; 183 184 nls_name.name = NULL; 185 if (name->type != FILE_NAME_DOS) { /* Case 2. */ 186 ntfs_debug("Case 2."); 187 nls_name.len = (unsigned)ntfs_ucstonls(vol, 188 (ntfschar*)&name->name, name->len, 189 (unsigned char**)&nls_name.name, 0); 190 kfree(name); 191 } else /* if (name->type == FILE_NAME_DOS) */ { /* Case 3. */ 192 FILE_NAME_ATTR *fn; 193 194 ntfs_debug("Case 3."); 195 kfree(name); 196 197 /* Find the WIN32 name corresponding to the matched DOS name. */ 198 ni = NTFS_I(dent_inode); 199 m = map_mft_record(ni); 200 if (IS_ERR(m)) { 201 err = PTR_ERR(m); 202 m = NULL; 203 ctx = NULL; 204 goto err_out; 205 } 206 ctx = ntfs_attr_get_search_ctx(ni, m); 207 if (unlikely(!ctx)) { 208 err = -ENOMEM; 209 goto err_out; 210 } 211 do { 212 ATTR_RECORD *a; 213 u32 val_len; 214 215 err = ntfs_attr_lookup(AT_FILE_NAME, NULL, 0, 0, 0, 216 NULL, 0, ctx); 217 if (unlikely(err)) { 218 ntfs_error(vol->sb, "Inode corrupt: No WIN32 " 219 "namespace counterpart to DOS " 220 "file name. Run chkdsk."); 221 if (err == -ENOENT) 222 err = -EIO; 223 goto err_out; 224 } 225 /* Consistency checks. */ 226 a = ctx->attr; 227 if (a->non_resident || a->flags) 228 goto eio_err_out; 229 val_len = le32_to_cpu(a->data.resident.value_length); 230 if (le16_to_cpu(a->data.resident.value_offset) + 231 val_len > le32_to_cpu(a->length)) 232 goto eio_err_out; 233 fn = (FILE_NAME_ATTR*)((u8*)ctx->attr + le16_to_cpu( 234 ctx->attr->data.resident.value_offset)); 235 if ((u32)(fn->file_name_length * sizeof(ntfschar) + 236 sizeof(FILE_NAME_ATTR)) > val_len) 237 goto eio_err_out; 238 } while (fn->file_name_type != FILE_NAME_WIN32); 239 240 /* Convert the found WIN32 name to current NLS code page. */ 241 nls_name.len = (unsigned)ntfs_ucstonls(vol, 242 (ntfschar*)&fn->file_name, fn->file_name_length, 243 (unsigned char**)&nls_name.name, 0); 244 245 ntfs_attr_put_search_ctx(ctx); 246 unmap_mft_record(ni); 247 } 248 m = NULL; 249 ctx = NULL; 250 251 /* Check if a conversion error occurred. */ 252 if ((signed)nls_name.len < 0) { 253 err = (signed)nls_name.len; 254 goto err_out; 255 } 256 nls_name.hash = full_name_hash(nls_name.name, nls_name.len); 257 258 /* 259 * Note: No need for dent->d_lock lock as i_mutex is held on the 260 * parent inode. 261 */ 262 263 /* Does a dentry matching the nls_name exist already? */ 264 real_dent = d_lookup(dent->d_parent, &nls_name); 265 /* If not, create it now. */ 266 if (!real_dent) { 267 real_dent = d_alloc(dent->d_parent, &nls_name); 268 kfree(nls_name.name); 269 if (!real_dent) { 270 err = -ENOMEM; 271 goto err_out; 272 } 273 new_dent = d_splice_alias(dent_inode, real_dent); 274 if (new_dent) 275 dput(real_dent); 276 else 277 new_dent = real_dent; 278 ntfs_debug("Done. (Created new dentry.)"); 279 return new_dent; 280 } 281 kfree(nls_name.name); 282 /* Matching dentry exists, check if it is negative. */ 283 if (real_dent->d_inode) { 284 if (unlikely(real_dent->d_inode != dent_inode)) { 285 /* This can happen because bad inodes are unhashed. */ 286 BUG_ON(!is_bad_inode(dent_inode)); 287 BUG_ON(!is_bad_inode(real_dent->d_inode)); 288 } 289 /* 290 * Already have the inode and the dentry attached, decrement 291 * the reference count to balance the ntfs_iget() we did 292 * earlier on. We found the dentry using d_lookup() so it 293 * cannot be disconnected and thus we do not need to worry 294 * about any NFS/disconnectedness issues here. 295 */ 296 iput(dent_inode); 297 ntfs_debug("Done. (Already had inode and dentry.)"); 298 return real_dent; 299 } 300 /* 301 * Negative dentry: instantiate it unless the inode is a directory and 302 * has a 'disconnected' dentry (i.e. IS_ROOT and DCACHE_DISCONNECTED), 303 * in which case d_move() that in place of the found dentry. 304 */ 305 if (!S_ISDIR(dent_inode->i_mode)) { 306 /* Not a directory; everything is easy. */ 307 d_instantiate(real_dent, dent_inode); 308 ntfs_debug("Done. (Already had negative file dentry.)"); 309 return real_dent; 310 } 311 spin_lock(&dcache_lock); 312 if (list_empty(&dent_inode->i_dentry)) { 313 /* 314 * Directory without a 'disconnected' dentry; we need to do 315 * d_instantiate() by hand because it takes dcache_lock which 316 * we already hold. 317 */ 318 list_add(&real_dent->d_alias, &dent_inode->i_dentry); 319 real_dent->d_inode = dent_inode; 320 spin_unlock(&dcache_lock); 321 security_d_instantiate(real_dent, dent_inode); 322 ntfs_debug("Done. (Already had negative directory dentry.)"); 323 return real_dent; 324 } 325 /* 326 * Directory with a 'disconnected' dentry; get a reference to the 327 * 'disconnected' dentry. 328 */ 329 new_dent = list_entry(dent_inode->i_dentry.next, struct dentry, 330 d_alias); 331 dget_locked(new_dent); 332 spin_unlock(&dcache_lock); 333 /* Do security vodoo. */ 334 security_d_instantiate(real_dent, dent_inode); 335 /* Move new_dent in place of real_dent. */ 336 d_move(new_dent, real_dent); 337 /* Balance the ntfs_iget() we did above. */ 338 iput(dent_inode); 339 /* Throw away real_dent. */ 340 dput(real_dent); 341 /* Use new_dent as the actual dentry. */ 342 ntfs_debug("Done. (Already had negative, disconnected directory " 343 "dentry.)"); 344 return new_dent; 345 346 eio_err_out: 347 ntfs_error(vol->sb, "Illegal file name attribute. Run chkdsk."); 348 err = -EIO; 349 err_out: 350 if (ctx) 351 ntfs_attr_put_search_ctx(ctx); 352 if (m) 353 unmap_mft_record(ni); 354 iput(dent_inode); 355 ntfs_error(vol->sb, "Failed, returning error code %i.", err); 356 return ERR_PTR(err); 357 } 358 } 359 360 /** 361 * Inode operations for directories. 362 */ 363 const struct inode_operations ntfs_dir_inode_ops = { 364 .lookup = ntfs_lookup, /* VFS: Lookup directory. */ 365 }; 366 367 /** 368 * ntfs_get_parent - find the dentry of the parent of a given directory dentry 369 * @child_dent: dentry of the directory whose parent directory to find 370 * 371 * Find the dentry for the parent directory of the directory specified by the 372 * dentry @child_dent. This function is called from 373 * fs/exportfs/expfs.c::find_exported_dentry() which in turn is called from the 374 * default ->decode_fh() which is export_decode_fh() in the same file. 375 * 376 * The code is based on the ext3 ->get_parent() implementation found in 377 * fs/ext3/namei.c::ext3_get_parent(). 378 * 379 * Note: ntfs_get_parent() is called with @child_dent->d_inode->i_mutex down. 380 * 381 * Return the dentry of the parent directory on success or the error code on 382 * error (IS_ERR() is true). 383 */ 384 static struct dentry *ntfs_get_parent(struct dentry *child_dent) 385 { 386 struct inode *vi = child_dent->d_inode; 387 ntfs_inode *ni = NTFS_I(vi); 388 MFT_RECORD *mrec; 389 ntfs_attr_search_ctx *ctx; 390 ATTR_RECORD *attr; 391 FILE_NAME_ATTR *fn; 392 struct inode *parent_vi; 393 struct dentry *parent_dent; 394 unsigned long parent_ino; 395 int err; 396 397 ntfs_debug("Entering for inode 0x%lx.", vi->i_ino); 398 /* Get the mft record of the inode belonging to the child dentry. */ 399 mrec = map_mft_record(ni); 400 if (IS_ERR(mrec)) 401 return (struct dentry *)mrec; 402 /* Find the first file name attribute in the mft record. */ 403 ctx = ntfs_attr_get_search_ctx(ni, mrec); 404 if (unlikely(!ctx)) { 405 unmap_mft_record(ni); 406 return ERR_PTR(-ENOMEM); 407 } 408 try_next: 409 err = ntfs_attr_lookup(AT_FILE_NAME, NULL, 0, CASE_SENSITIVE, 0, NULL, 410 0, ctx); 411 if (unlikely(err)) { 412 ntfs_attr_put_search_ctx(ctx); 413 unmap_mft_record(ni); 414 if (err == -ENOENT) 415 ntfs_error(vi->i_sb, "Inode 0x%lx does not have a " 416 "file name attribute. Run chkdsk.", 417 vi->i_ino); 418 return ERR_PTR(err); 419 } 420 attr = ctx->attr; 421 if (unlikely(attr->non_resident)) 422 goto try_next; 423 fn = (FILE_NAME_ATTR *)((u8 *)attr + 424 le16_to_cpu(attr->data.resident.value_offset)); 425 if (unlikely((u8 *)fn + le32_to_cpu(attr->data.resident.value_length) > 426 (u8*)attr + le32_to_cpu(attr->length))) 427 goto try_next; 428 /* Get the inode number of the parent directory. */ 429 parent_ino = MREF_LE(fn->parent_directory); 430 /* Release the search context and the mft record of the child. */ 431 ntfs_attr_put_search_ctx(ctx); 432 unmap_mft_record(ni); 433 /* Get the inode of the parent directory. */ 434 parent_vi = ntfs_iget(vi->i_sb, parent_ino); 435 if (IS_ERR(parent_vi) || unlikely(is_bad_inode(parent_vi))) { 436 if (!IS_ERR(parent_vi)) 437 iput(parent_vi); 438 ntfs_error(vi->i_sb, "Failed to get parent directory inode " 439 "0x%lx of child inode 0x%lx.", parent_ino, 440 vi->i_ino); 441 return ERR_PTR(-EACCES); 442 } 443 /* Finally get a dentry for the parent directory and return it. */ 444 parent_dent = d_alloc_anon(parent_vi); 445 if (unlikely(!parent_dent)) { 446 iput(parent_vi); 447 return ERR_PTR(-ENOMEM); 448 } 449 ntfs_debug("Done for inode 0x%lx.", vi->i_ino); 450 return parent_dent; 451 } 452 453 static struct inode *ntfs_nfs_get_inode(struct super_block *sb, 454 u64 ino, u32 generation) 455 { 456 struct inode *inode; 457 458 inode = ntfs_iget(sb, ino); 459 if (!IS_ERR(inode)) { 460 if (is_bad_inode(inode) || inode->i_generation != generation) { 461 iput(inode); 462 inode = ERR_PTR(-ESTALE); 463 } 464 } 465 466 return inode; 467 } 468 469 static struct dentry *ntfs_fh_to_dentry(struct super_block *sb, struct fid *fid, 470 int fh_len, int fh_type) 471 { 472 return generic_fh_to_dentry(sb, fid, fh_len, fh_type, 473 ntfs_nfs_get_inode); 474 } 475 476 static struct dentry *ntfs_fh_to_parent(struct super_block *sb, struct fid *fid, 477 int fh_len, int fh_type) 478 { 479 return generic_fh_to_parent(sb, fid, fh_len, fh_type, 480 ntfs_nfs_get_inode); 481 } 482 483 /** 484 * Export operations allowing NFS exporting of mounted NTFS partitions. 485 * 486 * We use the default ->encode_fh() for now. Note that they 487 * use 32 bits to store the inode number which is an unsigned long so on 64-bit 488 * architectures is usually 64 bits so it would all fail horribly on huge 489 * volumes. I guess we need to define our own encode and decode fh functions 490 * that store 64-bit inode numbers at some point but for now we will ignore the 491 * problem... 492 * 493 * We also use the default ->get_name() helper (used by ->decode_fh() via 494 * fs/exportfs/expfs.c::find_exported_dentry()) as that is completely fs 495 * independent. 496 * 497 * The default ->get_parent() just returns -EACCES so we have to provide our 498 * own and the default ->get_dentry() is incompatible with NTFS due to not 499 * allowing the inode number 0 which is used in NTFS for the system file $MFT 500 * and due to using iget() whereas NTFS needs ntfs_iget(). 501 */ 502 const struct export_operations ntfs_export_ops = { 503 .get_parent = ntfs_get_parent, /* Find the parent of a given 504 directory. */ 505 .fh_to_dentry = ntfs_fh_to_dentry, 506 .fh_to_parent = ntfs_fh_to_parent, 507 }; 508