fs/ntfs/index.c

   1 /*
   2  * index.c - NTFS kernel index handling.  Part of the Linux-NTFS project.
   3  *
   4  * Copyright (c) 2004-2005 Anton Altaparmakov
   5  *
   6  * This program/include file is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License as published
   8  * by the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program/include file is distributed in the hope that it will be
  12  * useful, but WITHOUT ANY WARRANTY; without even the implied warranty
  13  * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program (in the main directory of the Linux-NTFS
  18  * distribution in the file COPYING); if not, write to the Free Software
  19  * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  20  */
  21
  22 #include "aops.h"
  23 #include "collate.h"
  24 #include "debug.h"
  25 #include "index.h"
  26 #include "ntfs.h"
  27
  28 /**
  29  * ntfs_index_ctx_get - allocate and initialize a new index context
  30  * @idx_ni:     ntfs index inode with which to initialize the context
  31  *
  32  * Allocate a new index context, initialize it with @idx_ni and return it.
  33  * Return NULL if allocation failed.
  34  *
  35  * Locking:  Caller must hold i_sem on the index inode.
  36  */
  37 ntfs_index_context *ntfs_index_ctx_get(ntfs_inode *idx_ni)
  38 {
  39         ntfs_index_context *ictx;
  40
  41         ictx = kmem_cache_alloc(ntfs_index_ctx_cache, SLAB_NOFS);
  42         if (ictx)
  43                 *ictx = (ntfs_index_context){ .idx_ni = idx_ni };
  44         return ictx;
  45 }
  46
  47 /**
  48  * ntfs_index_ctx_put - release an index context
  49  * @ictx:       index context to free
  50  *
  51  * Release the index context @ictx, releasing all associated resources.
  52  *
  53  * Locking:  Caller must hold i_sem on the index inode.
  54  */
  55 void ntfs_index_ctx_put(ntfs_index_context *ictx)
  56 {
  57         if (ictx->entry) {
  58                 if (ictx->is_in_root) {
  59                         if (ictx->actx)
  60                                 ntfs_attr_put_search_ctx(ictx->actx);
  61                         if (ictx->base_ni)
  62                                 unmap_mft_record(ictx->base_ni);
  63                 } else {
  64                         struct page *page = ictx->page;
  65                         if (page) {
  66                                 BUG_ON(!PageLocked(page));
  67                                 unlock_page(page);
  68                                 ntfs_unmap_page(page);
  69                         }
  70                 }
  71         }
  72         kmem_cache_free(ntfs_index_ctx_cache, ictx);
  73         return;
  74 }
  75
  76 /**
  77  * ntfs_index_lookup - find a key in an index and return its index entry
  78  * @key:        [IN] key for which to search in the index
  79  * @key_len:    [IN] length of @key in bytes
  80  * @ictx:       [IN/OUT] context describing the index and the returned entry
  81  *
  82  * Before calling ntfs_index_lookup(), @ictx must have been obtained from a
  83  * call to ntfs_index_ctx_get().
  84  *
  85  * Look for the @key in the index specified by the index lookup context @ictx.
  86  * ntfs_index_lookup() walks the contents of the index looking for the @key.
  87  *
  88  * If the @key is found in the index, 0 is returned and @ictx is setup to
  89  * describe the index entry containing the matching @key.  @ictx->entry is the
  90  * index entry and @ictx->data and @ictx->data_len are the index entry data and
  91  * its length in bytes, respectively.
  92  *
  93  * If the @key is not found in the index, -ENOENT is returned and @ictx is
  94  * setup to describe the index entry whose key collates immediately after the
  95  * search @key, i.e. this is the position in the index at which an index entry
  96  * with a key of @key would need to be inserted.
  97  *
  98  * If an error occurs return the negative error code and @ictx is left
  99  * untouched.
 100  *
 101  * When finished with the entry and its data, call ntfs_index_ctx_put() to free
 102  * the context and other associated resources.
 103  *
 104  * If the index entry was modified, call flush_dcache_index_entry_page()
 105  * immediately after the modification and either ntfs_index_entry_mark_dirty()
 106  * or ntfs_index_entry_write() before the call to ntfs_index_ctx_put() to
 107  * ensure that the changes are written to disk.
 108  *
 109  * Locking:  - Caller must hold i_sem on the index inode.
 110  *           - Each page cache page in the index allocation mapping must be
 111  *             locked whilst being accessed otherwise we may find a corrupt
 112  *             page due to it being under ->writepage at the moment which
 113  *             applies the mst protection fixups before writing out and then
 114  *             removes them again after the write is complete after which it
 115  *             unlocks the page.
 116  */
 117 int ntfs_index_lookup(const void *key, const int key_len,
 118                 ntfs_index_context *ictx)
 119 {
 120         VCN vcn, old_vcn;
 121         ntfs_inode *idx_ni = ictx->idx_ni;
 122         ntfs_volume *vol = idx_ni->vol;
 123         struct super_block *sb = vol->sb;
 124         ntfs_inode *base_ni = idx_ni->ext.base_ntfs_ino;
 125         MFT_RECORD *m;
 126         INDEX_ROOT *ir;
 127         INDEX_ENTRY *ie;
 128         INDEX_ALLOCATION *ia;
 129         u8 *index_end, *kaddr;
 130         ntfs_attr_search_ctx *actx;
 131         struct address_space *ia_mapping;
 132         struct page *page;
 133         int rc, err = 0;
 134
 135         ntfs_debug("Entering.");
 136         BUG_ON(!NInoAttr(idx_ni));
 137         BUG_ON(idx_ni->type != AT_INDEX_ALLOCATION);
 138         BUG_ON(idx_ni->nr_extents != -1);
 139         BUG_ON(!base_ni);
 140         BUG_ON(!key);
 141         BUG_ON(key_len <= 0);
 142         if (!ntfs_is_collation_rule_supported(
 143                         idx_ni->itype.index.collation_rule)) {
 144                 ntfs_error(sb, "Index uses unsupported collation rule 0x%x.  "
 145                                 "Aborting lookup.", le32_to_cpu(
 146                                 idx_ni->itype.index.collation_rule));
 147                 return -EOPNOTSUPP;
 148         }
 149         /* Get hold of the mft record for the index inode. */
 150         m = map_mft_record(base_ni);
 151         if (IS_ERR(m)) {
 152                 ntfs_error(sb, "map_mft_record() failed with error code %ld.",
 153                                 -PTR_ERR(m));
 154                 return PTR_ERR(m);
 155         }
 156         actx = ntfs_attr_get_search_ctx(base_ni, m);
 157         if (unlikely(!actx)) {
 158                 err = -ENOMEM;
 159                 goto err_out;
 160         }
 161         /* Find the index root attribute in the mft record. */
 162         err = ntfs_attr_lookup(AT_INDEX_ROOT, idx_ni->name, idx_ni->name_len,
 163                         CASE_SENSITIVE, 0, NULL, 0, actx);
 164         if (unlikely(err)) {
 165                 if (err == -ENOENT) {
 166                         ntfs_error(sb, "Index root attribute missing in inode "
 167                                         "0x%lx.", idx_ni->mft_no);
 168                         err = -EIO;
 169                 }
 170                 goto err_out;
 171         }
 172         /* Get to the index root value (it has been verified in read_inode). */
 173         ir = (INDEX_ROOT*)((u8*)actx->attr +
 174                         le16_to_cpu(actx->attr->data.resident.value_offset));
 175         index_end = (u8*)&ir->index + le32_to_cpu(ir->index.index_length);
 176         /* The first index entry. */
 177         ie = (INDEX_ENTRY*)((u8*)&ir->index +
 178                         le32_to_cpu(ir->index.entries_offset));
 179         /*
 180          * Loop until we exceed valid memory (corruption case) or until we
 181          * reach the last entry.
 182          */
 183         for (;; ie = (INDEX_ENTRY*)((u8*)ie + le16_to_cpu(ie->length))) {
 184                 /* Bounds checks. */
 185                 if ((u8*)ie < (u8*)actx->mrec || (u8*)ie +
 186                                 sizeof(INDEX_ENTRY_HEADER) > index_end ||
 187                                 (u8*)ie + le16_to_cpu(ie->length) > index_end)
 188                         goto idx_err_out;
 189                 /*
 190                  * The last entry cannot contain a key.  It can however contain
 191                  * a pointer to a child node in the B+tree so we just break out.
 192                  */
 193                 if (ie->flags & INDEX_ENTRY_END)
 194                         break;
 195                 /* Further bounds checks. */
 196                 if ((u32)sizeof(INDEX_ENTRY_HEADER) +
 197                                 le16_to_cpu(ie->key_length) >
 198                                 le16_to_cpu(ie->data.vi.data_offset) ||
 199                                 (u32)le16_to_cpu(ie->data.vi.data_offset) +
 200                                 le16_to_cpu(ie->data.vi.data_length) >
 201                                 le16_to_cpu(ie->length))
 202                         goto idx_err_out;
 203                 /* If the keys match perfectly, we setup @ictx and return 0. */
 204                 if ((key_len == le16_to_cpu(ie->key_length)) && !memcmp(key,
 205                                 &ie->key, key_len)) {
 206 ir_done:
 207                         ictx->is_in_root = TRUE;
 208                         ictx->actx = actx;
 209                         ictx->base_ni = base_ni;
 210                         ictx->ia = NULL;
 211                         ictx->page = NULL;
 212 done:
 213                         ictx->entry = ie;
 214                         ictx->data = (u8*)ie +
 215                                         le16_to_cpu(ie->data.vi.data_offset);
 216                         ictx->data_len = le16_to_cpu(ie->data.vi.data_length);
 217                         ntfs_debug("Done.");
 218                         return err;
 219                 }
 220                 /*
 221                  * Not a perfect match, need to do full blown collation so we
 222                  * know which way in the B+tree we have to go.
 223                  */
 224                 rc = ntfs_collate(vol, idx_ni->itype.index.collation_rule, key,
 225                                 key_len, &ie->key, le16_to_cpu(ie->key_length));
 226                 /*
 227                  * If @key collates before the key of the current entry, there
 228                  * is definitely no such key in this index but we might need to
 229                  * descend into the B+tree so we just break out of the loop.
 230                  */
 231                 if (rc == -1)
 232                         break;
 233                 /*
 234                  * A match should never happen as the memcmp() call should have
 235                  * cought it, but we still treat it correctly.
 236                  */
 237                 if (!rc)
 238                         goto ir_done;
 239                 /* The keys are not equal, continue the search. */
 240         }
 241         /*
 242          * We have finished with this index without success.  Check for the
 243          * presence of a child node and if not present setup @ictx and return
 244          * -ENOENT.
 245          */
 246         if (!(ie->flags & INDEX_ENTRY_NODE)) {
 247                 ntfs_debug("Entry not found.");
 248                 err = -ENOENT;
 249                 goto ir_done;
 250         } /* Child node present, descend into it. */
 251         /* Consistency check: Verify that an index allocation exists. */
 252         if (!NInoIndexAllocPresent(idx_ni)) {
 253                 ntfs_error(sb, "No index allocation attribute but index entry "
 254                                 "requires one.  Inode 0x%lx is corrupt or "
 255                                 "driver bug.", idx_ni->mft_no);
 256                 goto err_out;
 257         }
 258         /* Get the starting vcn of the index_block holding the child node. */
 259         vcn = sle64_to_cpup((sle64*)((u8*)ie + le16_to_cpu(ie->length) - 8));
 260         ia_mapping = VFS_I(idx_ni)->i_mapping;
 261         /*
 262          * We are done with the index root and the mft record.  Release them,
 263          * otherwise we deadlock with ntfs_map_page().
 264          */
 265         ntfs_attr_put_search_ctx(actx);
 266         unmap_mft_record(base_ni);
 267         m = NULL;
 268         actx = NULL;
 269 descend_into_child_node:
 270         /*
 271          * Convert vcn to index into the index allocation attribute in units
 272          * of PAGE_CACHE_SIZE and map the page cache page, reading it from
 273          * disk if necessary.
 274          */
 275         page = ntfs_map_page(ia_mapping, vcn <<
 276                         idx_ni->itype.index.vcn_size_bits >> PAGE_CACHE_SHIFT);
 277         if (IS_ERR(page)) {
 278                 ntfs_error(sb, "Failed to map index page, error %ld.",
 279                                 -PTR_ERR(page));
 280                 err = PTR_ERR(page);
 281                 goto err_out;
 282         }
 283         lock_page(page);
 284         kaddr = (u8*)page_address(page);
 285 fast_descend_into_child_node:
 286         /* Get to the index allocation block. */
 287         ia = (INDEX_ALLOCATION*)(kaddr + ((vcn <<
 288                         idx_ni->itype.index.vcn_size_bits) & ~PAGE_CACHE_MASK));
 289         /* Bounds checks. */
 290         if ((u8*)ia < kaddr || (u8*)ia > kaddr + PAGE_CACHE_SIZE) {
 291                 ntfs_error(sb, "Out of bounds check failed.  Corrupt inode "
 292                                 "0x%lx or driver bug.", idx_ni->mft_no);
 293                 goto unm_err_out;
 294         }
 295         /* Catch multi sector transfer fixup errors. */
 296         if (unlikely(!ntfs_is_indx_record(ia->magic))) {
 297                 ntfs_error(sb, "Index record with vcn 0x%llx is corrupt.  "
 298                                 "Corrupt inode 0x%lx.  Run chkdsk.",
 299                                 (long long)vcn, idx_ni->mft_no);
 300                 goto unm_err_out;
 301         }
 302         if (sle64_to_cpu(ia->index_block_vcn) != vcn) {
 303                 ntfs_error(sb, "Actual VCN (0x%llx) of index buffer is "
 304                                 "different from expected VCN (0x%llx).  Inode "
 305                                 "0x%lx is corrupt or driver bug.",
 306                                 (unsigned long long)
 307                                 sle64_to_cpu(ia->index_block_vcn),
 308                                 (unsigned long long)vcn, idx_ni->mft_no);
 309                 goto unm_err_out;
 310         }
 311         if (le32_to_cpu(ia->index.allocated_size) + 0x18 !=
 312                         idx_ni->itype.index.block_size) {
 313                 ntfs_error(sb, "Index buffer (VCN 0x%llx) of inode 0x%lx has "
 314                                 "a size (%u) differing from the index "
 315                                 "specified size (%u).  Inode is corrupt or "
 316                                 "driver bug.", (unsigned long long)vcn,
 317                                 idx_ni->mft_no,
 318                                 le32_to_cpu(ia->index.allocated_size) + 0x18,
 319                                 idx_ni->itype.index.block_size);
 320                 goto unm_err_out;
 321         }
 322         index_end = (u8*)ia + idx_ni->itype.index.block_size;
 323         if (index_end > kaddr + PAGE_CACHE_SIZE) {
 324                 ntfs_error(sb, "Index buffer (VCN 0x%llx) of inode 0x%lx "
 325                                 "crosses page boundary.  Impossible!  Cannot "
 326                                 "access!  This is probably a bug in the "
 327                                 "driver.", (unsigned long long)vcn,
 328                                 idx_ni->mft_no);
 329                 goto unm_err_out;
 330         }
 331         index_end = (u8*)&ia->index + le32_to_cpu(ia->index.index_length);
 332         if (index_end > (u8*)ia + idx_ni->itype.index.block_size) {
 333                 ntfs_error(sb, "Size of index buffer (VCN 0x%llx) of inode "
 334                                 "0x%lx exceeds maximum size.",
 335                                 (unsigned long long)vcn, idx_ni->mft_no);
 336                 goto unm_err_out;
 337         }
 338         /* The first index entry. */
 339         ie = (INDEX_ENTRY*)((u8*)&ia->index +
 340                         le32_to_cpu(ia->index.entries_offset));
 341         /*
 342          * Iterate similar to above big loop but applied to index buffer, thus
 343          * loop until we exceed valid memory (corruption case) or until we
 344          * reach the last entry.
 345          */
 346         for (;; ie = (INDEX_ENTRY*)((u8*)ie + le16_to_cpu(ie->length))) {
 347                 /* Bounds checks. */
 348                 if ((u8*)ie < (u8*)ia || (u8*)ie +
 349                                 sizeof(INDEX_ENTRY_HEADER) > index_end ||
 350                                 (u8*)ie + le16_to_cpu(ie->length) > index_end) {
 351                         ntfs_error(sb, "Index entry out of bounds in inode "
 352                                         "0x%lx.", idx_ni->mft_no);
 353                         goto unm_err_out;
 354                 }
 355                 /*
 356                  * The last entry cannot contain a key.  It can however contain
 357                  * a pointer to a child node in the B+tree so we just break out.
 358                  */
 359                 if (ie->flags & INDEX_ENTRY_END)
 360                         break;
 361                 /* Further bounds checks. */
 362                 if ((u32)sizeof(INDEX_ENTRY_HEADER) +
 363                                 le16_to_cpu(ie->key_length) >
 364                                 le16_to_cpu(ie->data.vi.data_offset) ||
 365                                 (u32)le16_to_cpu(ie->data.vi.data_offset) +
 366                                 le16_to_cpu(ie->data.vi.data_length) >
 367                                 le16_to_cpu(ie->length)) {
 368                         ntfs_error(sb, "Index entry out of bounds in inode "
 369                                         "0x%lx.", idx_ni->mft_no);
 370                         goto unm_err_out;
 371                 }
 372                 /* If the keys match perfectly, we setup @ictx and return 0. */
 373                 if ((key_len == le16_to_cpu(ie->key_length)) && !memcmp(key,
 374                                 &ie->key, key_len)) {
 375 ia_done:
 376                         ictx->is_in_root = FALSE;
 377                         ictx->actx = NULL;
 378                         ictx->base_ni = NULL;
 379                         ictx->ia = ia;
 380                         ictx->page = page;
 381                         goto done;
 382                 }
 383                 /*
 384                  * Not a perfect match, need to do full blown collation so we
 385                  * know which way in the B+tree we have to go.
 386                  */
 387                 rc = ntfs_collate(vol, idx_ni->itype.index.collation_rule, key,
 388                                 key_len, &ie->key, le16_to_cpu(ie->key_length));
 389                 /*
 390                  * If @key collates before the key of the current entry, there
 391                  * is definitely no such key in this index but we might need to
 392                  * descend into the B+tree so we just break out of the loop.
 393                  */
 394                 if (rc == -1)
 395                         break;
 396                 /*
 397                  * A match should never happen as the memcmp() call should have
 398                  * cought it, but we still treat it correctly.
 399                  */
 400                 if (!rc)
 401                         goto ia_done;
 402                 /* The keys are not equal, continue the search. */
 403         }
 404         /*
 405          * We have finished with this index buffer without success.  Check for
 406          * the presence of a child node and if not present return -ENOENT.
 407          */
 408         if (!(ie->flags & INDEX_ENTRY_NODE)) {
 409                 ntfs_debug("Entry not found.");
 410                 err = -ENOENT;
 411                 goto ia_done;
 412         }
 413         if ((ia->index.flags & NODE_MASK) == LEAF_NODE) {
 414                 ntfs_error(sb, "Index entry with child node found in a leaf "
 415                                 "node in inode 0x%lx.", idx_ni->mft_no);
 416                 goto unm_err_out;
 417         }
 418         /* Child node present, descend into it. */
 419         old_vcn = vcn;
 420         vcn = sle64_to_cpup((sle64*)((u8*)ie + le16_to_cpu(ie->length) - 8));
 421         if (vcn >= 0) {
 422                 /*
 423                  * If vcn is in the same page cache page as old_vcn we recycle
 424                  * the mapped page.
 425                  */
 426                 if (old_vcn << vol->cluster_size_bits >>
 427                                 PAGE_CACHE_SHIFT == vcn <<
 428                                 vol->cluster_size_bits >>
 429                                 PAGE_CACHE_SHIFT)
 430                         goto fast_descend_into_child_node;
 431                 unlock_page(page);
 432                 ntfs_unmap_page(page);
 433                 goto descend_into_child_node;
 434         }
 435         ntfs_error(sb, "Negative child node vcn in inode 0x%lx.",
 436                         idx_ni->mft_no);
 437 unm_err_out:
 438         unlock_page(page);
 439         ntfs_unmap_page(page);
 440 err_out:
 441         if (!err)
 442                 err = -EIO;
 443         if (actx)
 444                 ntfs_attr_put_search_ctx(actx);
 445         if (m)
 446                 unmap_mft_record(base_ni);
 447         return err;
 448 idx_err_out:
 449         ntfs_error(sb, "Corrupt index.  Aborting lookup.");
 450         goto err_out;
 451 }