Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/fs/ntfs/namei.c
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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 #include <linux/slab.h> 27 28 #include "attrib.h" 29 #include "debug.h" 30 #include "dir.h" 31 #include "mft.h" 32 #include "ntfs.h" 33 34 /** 35 * ntfs_lookup - find the inode represented by a dentry in a directory inode 36 * @dir_ino: directory inode in which to look for the inode 37 * @dent: dentry representing the inode to look for 38 * @nd: lookup nameidata 39 * 40 * In short, ntfs_lookup() looks for the inode represented by the dentry @dent 41 * in the directory inode @dir_ino and if found attaches the inode to the 42 * dentry @dent. 43 * 44 * In more detail, the dentry @dent specifies which inode to look for by 45 * supplying the name of the inode in @dent->d_name.name. ntfs_lookup() 46 * converts the name to Unicode and walks the contents of the directory inode 47 * @dir_ino looking for the converted Unicode name. If the name is found in the 48 * directory, the corresponding inode is loaded by calling ntfs_iget() on its 49 * inode number and the inode is associated with the dentry @dent via a call to 50 * d_splice_alias(). 51 * 52 * If the name is not found in the directory, a NULL inode is inserted into the 53 * dentry @dent via a call to d_add(). The dentry is then termed a negative 54 * dentry. 55 * 56 * Only if an actual error occurs, do we return an error via ERR_PTR(). 57 * 58 * In order to handle the case insensitivity issues of NTFS with regards to the 59 * dcache and the dcache requiring only one dentry per directory, we deal with 60 * dentry aliases that only differ in case in ->ntfs_lookup() while maintaining 61 * a case sensitive dcache. This means that we get the full benefit of dcache 62 * speed when the file/directory is looked up with the same case as returned by 63 * ->ntfs_readdir() but that a lookup for any other case (or for the short file 64 * name) will not find anything in dcache and will enter ->ntfs_lookup() 65 * instead, where we search the directory for a fully matching file name 66 * (including case) and if that is not found, we search for a file name that 67 * matches with different case and if that has non-POSIX semantics we return 68 * that. We actually do only one search (case sensitive) and keep tabs on 69 * whether we have found a case insensitive match in the process. 70 * 71 * To simplify matters for us, we do not treat the short vs long filenames as 72 * two hard links but instead if the lookup matches a short filename, we 73 * return the dentry for the corresponding long filename instead. 74 * 75 * There are three cases we need to distinguish here: 76 * 77 * 1) @dent perfectly matches (i.e. including case) a directory entry with a 78 * file name in the WIN32 or POSIX namespaces. In this case 79 * ntfs_lookup_inode_by_name() will return with name set to NULL and we 80 * just d_splice_alias() @dent. 81 * 2) @dent matches (not including case) a directory entry with a file name in 82 * the WIN32 namespace. In this case ntfs_lookup_inode_by_name() will return 83 * with name set to point to a kmalloc()ed ntfs_name structure containing 84 * the properly cased little endian Unicode name. We convert the name to the 85 * current NLS code page, search if a dentry with this name already exists 86 * and if so return that instead of @dent. At this point things are 87 * complicated by the possibility of 'disconnected' dentries due to NFS 88 * which we deal with appropriately (see the code comments). The VFS will 89 * then destroy the old @dent and use the one we returned. If a dentry is 90 * not found, we allocate a new one, d_splice_alias() it, and return it as 91 * above. 92 * 3) @dent matches either perfectly or not (i.e. we don't care about case) a 93 * directory entry with a file name in the DOS namespace. In this case 94 * ntfs_lookup_inode_by_name() will return with name set to point to a 95 * kmalloc()ed ntfs_name structure containing the mft reference (cpu endian) 96 * of the inode. We use the mft reference to read the inode and to find the 97 * file name in the WIN32 namespace corresponding to the matched short file 98 * name. We then convert the name to the current NLS code page, and proceed 99 * searching for a dentry with this name, etc, as in case 2), above. 100 * 101 * Locking: Caller must hold i_mutex on the directory. 102 */ 103 static struct dentry *ntfs_lookup(struct inode *dir_ino, struct dentry *dent, 104 unsigned int flags) 105 { 106 ntfs_volume *vol = NTFS_SB(dir_ino->i_sb); 107 struct inode *dent_inode; 108 ntfschar *uname; 109 ntfs_name *name = NULL; 110 MFT_REF mref; 111 unsigned long dent_ino; 112 int uname_len; 113 114 ntfs_debug("Looking up %s in directory inode 0x%lx.", 115 dent->d_name.name, dir_ino->i_ino); 116 /* Convert the name of the dentry to Unicode. */ 117 uname_len = ntfs_nlstoucs(vol, dent->d_name.name, dent->d_name.len, 118 &uname); 119 if (uname_len < 0) { 120 if (uname_len != -ENAMETOOLONG) 121 ntfs_error(vol->sb, "Failed to convert name to " 122 "Unicode."); 123 return ERR_PTR(uname_len); 124 } 125 mref = ntfs_lookup_inode_by_name(NTFS_I(dir_ino), uname, uname_len, 126 &name); 127 kmem_cache_free(ntfs_name_cache, uname); 128 if (!IS_ERR_MREF(mref)) { 129 dent_ino = MREF(mref); 130 ntfs_debug("Found inode 0x%lx. Calling ntfs_iget.", dent_ino); 131 dent_inode = ntfs_iget(vol->sb, dent_ino); 132 if (likely(!IS_ERR(dent_inode))) { 133 /* Consistency check. */ 134 if (is_bad_inode(dent_inode) || MSEQNO(mref) == 135 NTFS_I(dent_inode)->seq_no || 136 dent_ino == FILE_MFT) { 137 /* Perfect WIN32/POSIX match. -- Case 1. */ 138 if (!name) { 139 ntfs_debug("Done. (Case 1.)"); 140 return d_splice_alias(dent_inode, dent); 141 } 142 /* 143 * We are too indented. Handle imperfect 144 * matches and short file names further below. 145 */ 146 goto handle_name; 147 } 148 ntfs_error(vol->sb, "Found stale reference to inode " 149 "0x%lx (reference sequence number = " 150 "0x%x, inode sequence number = 0x%x), " 151 "returning -EIO. Run chkdsk.", 152 dent_ino, MSEQNO(mref), 153 NTFS_I(dent_inode)->seq_no); 154 iput(dent_inode); 155 dent_inode = ERR_PTR(-EIO); 156 } else 157 ntfs_error(vol->sb, "ntfs_iget(0x%lx) failed with " 158 "error code %li.", dent_ino, 159 PTR_ERR(dent_inode)); 160 kfree(name); 161 /* Return the error code. */ 162 return (struct dentry *)dent_inode; 163 } 164 /* It is guaranteed that @name is no longer allocated at this point. */ 165 if (MREF_ERR(mref) == -ENOENT) { 166 ntfs_debug("Entry was not found, adding negative dentry."); 167 /* The dcache will handle negative entries. */ 168 d_add(dent, NULL); 169 ntfs_debug("Done."); 170 return NULL; 171 } 172 ntfs_error(vol->sb, "ntfs_lookup_ino_by_name() failed with error " 173 "code %i.", -MREF_ERR(mref)); 174 return ERR_PTR(MREF_ERR(mref)); 175 // TODO: Consider moving this lot to a separate function! (AIA) 176 handle_name: 177 { 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 dent = d_add_ci(dent, dent_inode, &nls_name); 259 kfree(nls_name.name); 260 return dent; 261 262 eio_err_out: 263 ntfs_error(vol->sb, "Illegal file name attribute. Run chkdsk."); 264 err = -EIO; 265 err_out: 266 if (ctx) 267 ntfs_attr_put_search_ctx(ctx); 268 if (m) 269 unmap_mft_record(ni); 270 iput(dent_inode); 271 ntfs_error(vol->sb, "Failed, returning error code %i.", err); 272 return ERR_PTR(err); 273 } 274 } 275 276 /** 277 * Inode operations for directories. 278 */ 279 const struct inode_operations ntfs_dir_inode_ops = { 280 .lookup = ntfs_lookup, /* VFS: Lookup directory. */ 281 }; 282 283 /** 284 * ntfs_get_parent - find the dentry of the parent of a given directory dentry 285 * @child_dent: dentry of the directory whose parent directory to find 286 * 287 * Find the dentry for the parent directory of the directory specified by the 288 * dentry @child_dent. This function is called from 289 * fs/exportfs/expfs.c::find_exported_dentry() which in turn is called from the 290 * default ->decode_fh() which is export_decode_fh() in the same file. 291 * 292 * The code is based on the ext3 ->get_parent() implementation found in 293 * fs/ext3/namei.c::ext3_get_parent(). 294 * 295 * Note: ntfs_get_parent() is called with @child_dent->d_inode->i_mutex down. 296 * 297 * Return the dentry of the parent directory on success or the error code on 298 * error (IS_ERR() is true). 299 */ 300 static struct dentry *ntfs_get_parent(struct dentry *child_dent) 301 { 302 struct inode *vi = child_dent->d_inode; 303 ntfs_inode *ni = NTFS_I(vi); 304 MFT_RECORD *mrec; 305 ntfs_attr_search_ctx *ctx; 306 ATTR_RECORD *attr; 307 FILE_NAME_ATTR *fn; 308 unsigned long parent_ino; 309 int err; 310 311 ntfs_debug("Entering for inode 0x%lx.", vi->i_ino); 312 /* Get the mft record of the inode belonging to the child dentry. */ 313 mrec = map_mft_record(ni); 314 if (IS_ERR(mrec)) 315 return (struct dentry *)mrec; 316 /* Find the first file name attribute in the mft record. */ 317 ctx = ntfs_attr_get_search_ctx(ni, mrec); 318 if (unlikely(!ctx)) { 319 unmap_mft_record(ni); 320 return ERR_PTR(-ENOMEM); 321 } 322 try_next: 323 err = ntfs_attr_lookup(AT_FILE_NAME, NULL, 0, CASE_SENSITIVE, 0, NULL, 324 0, ctx); 325 if (unlikely(err)) { 326 ntfs_attr_put_search_ctx(ctx); 327 unmap_mft_record(ni); 328 if (err == -ENOENT) 329 ntfs_error(vi->i_sb, "Inode 0x%lx does not have a " 330 "file name attribute. Run chkdsk.", 331 vi->i_ino); 332 return ERR_PTR(err); 333 } 334 attr = ctx->attr; 335 if (unlikely(attr->non_resident)) 336 goto try_next; 337 fn = (FILE_NAME_ATTR *)((u8 *)attr + 338 le16_to_cpu(attr->data.resident.value_offset)); 339 if (unlikely((u8 *)fn + le32_to_cpu(attr->data.resident.value_length) > 340 (u8*)attr + le32_to_cpu(attr->length))) 341 goto try_next; 342 /* Get the inode number of the parent directory. */ 343 parent_ino = MREF_LE(fn->parent_directory); 344 /* Release the search context and the mft record of the child. */ 345 ntfs_attr_put_search_ctx(ctx); 346 unmap_mft_record(ni); 347 348 return d_obtain_alias(ntfs_iget(vi->i_sb, parent_ino)); 349 } 350 351 static struct inode *ntfs_nfs_get_inode(struct super_block *sb, 352 u64 ino, u32 generation) 353 { 354 struct inode *inode; 355 356 inode = ntfs_iget(sb, ino); 357 if (!IS_ERR(inode)) { 358 if (is_bad_inode(inode) || inode->i_generation != generation) { 359 iput(inode); 360 inode = ERR_PTR(-ESTALE); 361 } 362 } 363 364 return inode; 365 } 366 367 static struct dentry *ntfs_fh_to_dentry(struct super_block *sb, struct fid *fid, 368 int fh_len, int fh_type) 369 { 370 return generic_fh_to_dentry(sb, fid, fh_len, fh_type, 371 ntfs_nfs_get_inode); 372 } 373 374 static struct dentry *ntfs_fh_to_parent(struct super_block *sb, struct fid *fid, 375 int fh_len, int fh_type) 376 { 377 return generic_fh_to_parent(sb, fid, fh_len, fh_type, 378 ntfs_nfs_get_inode); 379 } 380 381 /** 382 * Export operations allowing NFS exporting of mounted NTFS partitions. 383 * 384 * We use the default ->encode_fh() for now. Note that they 385 * use 32 bits to store the inode number which is an unsigned long so on 64-bit 386 * architectures is usually 64 bits so it would all fail horribly on huge 387 * volumes. I guess we need to define our own encode and decode fh functions 388 * that store 64-bit inode numbers at some point but for now we will ignore the 389 * problem... 390 * 391 * We also use the default ->get_name() helper (used by ->decode_fh() via 392 * fs/exportfs/expfs.c::find_exported_dentry()) as that is completely fs 393 * independent. 394 * 395 * The default ->get_parent() just returns -EACCES so we have to provide our 396 * own and the default ->get_dentry() is incompatible with NTFS due to not 397 * allowing the inode number 0 which is used in NTFS for the system file $MFT 398 * and due to using iget() whereas NTFS needs ntfs_iget(). 399 */ 400 const struct export_operations ntfs_export_ops = { 401 .get_parent = ntfs_get_parent, /* Find the parent of a given 402 directory. */ 403 .fh_to_dentry = ntfs_fh_to_dentry, 404 .fh_to_parent = ntfs_fh_to_parent, 405 };
Cache object: fdf453cd136b1bd1a660c26c92819c75
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