fs/ntfs/namei.c

   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         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         dent = d_add_ci(dent, dent_inode, &nls_name);
 258         kfree(nls_name.name);
 259         return dent;
 260
 261 eio_err_out:
 262         ntfs_error(vol->sb, "Illegal file name attribute. Run chkdsk.");
 263         err = -EIO;
 264 err_out:
 265         if (ctx)
 266                 ntfs_attr_put_search_ctx(ctx);
 267         if (m)
 268                 unmap_mft_record(ni);
 269         iput(dent_inode);
 270         ntfs_error(vol->sb, "Failed, returning error code %i.", err);
 271         return ERR_PTR(err);
 272    }
 273 }
 274
 275 /**
 276  * Inode operations for directories.
 277  */
 278 const struct inode_operations ntfs_dir_inode_ops = {
 279         .lookup = ntfs_lookup,  /* VFS: Lookup directory. */
 280 };
 281
 282 /**
 283  * ntfs_get_parent - find the dentry of the parent of a given directory dentry
 284  * @child_dent:         dentry of the directory whose parent directory to find
 285  *
 286  * Find the dentry for the parent directory of the directory specified by the
 287  * dentry @child_dent.  This function is called from
 288  * fs/exportfs/expfs.c::find_exported_dentry() which in turn is called from the
 289  * default ->decode_fh() which is export_decode_fh() in the same file.
 290  *
 291  * The code is based on the ext3 ->get_parent() implementation found in
 292  * fs/ext3/namei.c::ext3_get_parent().
 293  *
 294  * Note: ntfs_get_parent() is called with @child_dent->d_inode->i_mutex down.
 295  *
 296  * Return the dentry of the parent directory on success or the error code on
 297  * error (IS_ERR() is true).
 298  */
 299 static struct dentry *ntfs_get_parent(struct dentry *child_dent)
 300 {
 301         struct inode *vi = child_dent->d_inode;
 302         ntfs_inode *ni = NTFS_I(vi);
 303         MFT_RECORD *mrec;
 304         ntfs_attr_search_ctx *ctx;
 305         ATTR_RECORD *attr;
 306         FILE_NAME_ATTR *fn;
 307         unsigned long parent_ino;
 308         int err;
 309
 310         ntfs_debug("Entering for inode 0x%lx.", vi->i_ino);
 311         /* Get the mft record of the inode belonging to the child dentry. */
 312         mrec = map_mft_record(ni);
 313         if (IS_ERR(mrec))
 314                 return (struct dentry *)mrec;
 315         /* Find the first file name attribute in the mft record. */
 316         ctx = ntfs_attr_get_search_ctx(ni, mrec);
 317         if (unlikely(!ctx)) {
 318                 unmap_mft_record(ni);
 319                 return ERR_PTR(-ENOMEM);
 320         }
 321 try_next:
 322         err = ntfs_attr_lookup(AT_FILE_NAME, NULL, 0, CASE_SENSITIVE, 0, NULL,
 323                         0, ctx);
 324         if (unlikely(err)) {
 325                 ntfs_attr_put_search_ctx(ctx);
 326                 unmap_mft_record(ni);
 327                 if (err == -ENOENT)
 328                         ntfs_error(vi->i_sb, "Inode 0x%lx does not have a "
 329                                         "file name attribute.  Run chkdsk.",
 330                                         vi->i_ino);
 331                 return ERR_PTR(err);
 332         }
 333         attr = ctx->attr;
 334         if (unlikely(attr->non_resident))
 335                 goto try_next;
 336         fn = (FILE_NAME_ATTR *)((u8 *)attr +
 337                         le16_to_cpu(attr->data.resident.value_offset));
 338         if (unlikely((u8 *)fn + le32_to_cpu(attr->data.resident.value_length) >
 339                         (u8*)attr + le32_to_cpu(attr->length)))
 340                 goto try_next;
 341         /* Get the inode number of the parent directory. */
 342         parent_ino = MREF_LE(fn->parent_directory);
 343         /* Release the search context and the mft record of the child. */
 344         ntfs_attr_put_search_ctx(ctx);
 345         unmap_mft_record(ni);
 346
 347         return d_obtain_alias(ntfs_iget(vi->i_sb, parent_ino));
 348 }
 349
 350 static struct inode *ntfs_nfs_get_inode(struct super_block *sb,
 351                 u64 ino, u32 generation)
 352 {
 353         struct inode *inode;
 354
 355         inode = ntfs_iget(sb, ino);
 356         if (!IS_ERR(inode)) {
 357                 if (is_bad_inode(inode) || inode->i_generation != generation) {
 358                         iput(inode);
 359                         inode = ERR_PTR(-ESTALE);
 360                 }
 361         }
 362
 363         return inode;
 364 }
 365
 366 static struct dentry *ntfs_fh_to_dentry(struct super_block *sb, struct fid *fid,
 367                 int fh_len, int fh_type)
 368 {
 369         return generic_fh_to_dentry(sb, fid, fh_len, fh_type,
 370                                     ntfs_nfs_get_inode);
 371 }
 372
 373 static struct dentry *ntfs_fh_to_parent(struct super_block *sb, struct fid *fid,
 374                 int fh_len, int fh_type)
 375 {
 376         return generic_fh_to_parent(sb, fid, fh_len, fh_type,
 377                                     ntfs_nfs_get_inode);
 378 }
 379
 380 /**
 381  * Export operations allowing NFS exporting of mounted NTFS partitions.
 382  *
 383  * We use the default ->encode_fh() for now.  Note that they
 384  * use 32 bits to store the inode number which is an unsigned long so on 64-bit
 385  * architectures is usually 64 bits so it would all fail horribly on huge
 386  * volumes.  I guess we need to define our own encode and decode fh functions
 387  * that store 64-bit inode numbers at some point but for now we will ignore the
 388  * problem...
 389  *
 390  * We also use the default ->get_name() helper (used by ->decode_fh() via
 391  * fs/exportfs/expfs.c::find_exported_dentry()) as that is completely fs
 392  * independent.
 393  *
 394  * The default ->get_parent() just returns -EACCES so we have to provide our
 395  * own and the default ->get_dentry() is incompatible with NTFS due to not
 396  * allowing the inode number 0 which is used in NTFS for the system file $MFT
 397  * and due to using iget() whereas NTFS needs ntfs_iget().
 398  */
 399 const struct export_operations ntfs_export_ops = {
 400         .get_parent     = ntfs_get_parent,      /* Find the parent of a given
 401                                                    directory. */
 402         .fh_to_dentry   = ntfs_fh_to_dentry,
 403         .fh_to_parent   = ntfs_fh_to_parent,
 404 };