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 <linux/slab.h>
  23
  24 #include "aops.h"
  25 #include "collate.h"
  26 #include "debug.h"
  27 #include "index.h"
  28 #include "ntfs.h"
  29
  30 /**
  31  * ntfs_index_ctx_get - allocate and initialize a new index context
  32  * @idx_ni:     ntfs index inode with which to initialize the context
  33  *
  34  * Allocate a new index context, initialize it with @idx_ni and return it.
  35  * Return NULL if allocation failed.
  36  *
  37  * Locking:  Caller must hold i_mutex on the index inode.
  38  */
  39 ntfs_index_context *ntfs_index_ctx_get(ntfs_inode *idx_ni)
  40 {
  41         ntfs_index_context *ictx;
  42
  43         ictx = kmem_cache_alloc(ntfs_index_ctx_cache, GFP_NOFS);
  44         if (ictx)
  45                 *ictx = (ntfs_index_context){ .idx_ni = idx_ni };
  46         return ictx;
  47 }
  48
  49 /**
  50  * ntfs_index_ctx_put - release an index context
  51  * @ictx:       index context to free
  52  *
  53  * Release the index context @ictx, releasing all associated resources.
  54  *
  55  * Locking:  Caller must hold i_mutex on the index inode.
  56  */
  57 void ntfs_index_ctx_put(ntfs_index_context *ictx)
  58 {
  59         if (ictx->entry) {
  60                 if (ictx->is_in_root) {
  61                         if (ictx->actx)
  62                                 ntfs_attr_put_search_ctx(ictx->actx);
  63                         if (ictx->base_ni)
  64                                 unmap_mft_record(ictx->base_ni);
  65                 } else {
  66                         struct page *page = ictx->page;
  67                         if (page) {
  68                                 BUG_ON(!PageLocked(page));
  69                                 unlock_page(page);
  70                                 ntfs_unmap_page(page);
  71                         }
  72                 }
  73         }
  74         kmem_cache_free(ntfs_index_ctx_cache, ictx);
  75         return;
  76 }
  77
  78 /**
  79  * ntfs_index_lookup - find a key in an index and return its index entry
  80  * @key:        [IN] key for which to search in the index
  81  * @key_len:    [IN] length of @key in bytes
  82  * @ictx:       [IN/OUT] context describing the index and the returned entry
  83  *
  84  * Before calling ntfs_index_lookup(), @ictx must have been obtained from a
  85  * call to ntfs_index_ctx_get().
  86  *
  87  * Look for the @key in the index specified by the index lookup context @ictx.
  88  * ntfs_index_lookup() walks the contents of the index looking for the @key.
  89  *
  90  * If the @key is found in the index, 0 is returned and @ictx is setup to
  91  * describe the index entry containing the matching @key.  @ictx->entry is the
  92  * index entry and @ictx->data and @ictx->data_len are the index entry data and
  93  * its length in bytes, respectively.
  94  *
  95  * If the @key is not found in the index, -ENOENT is returned and @ictx is
  96  * setup to describe the index entry whose key collates immediately after the
  97  * search @key, i.e. this is the position in the index at which an index entry
  98  * with a key of @key would need to be inserted.
  99  *
 100  * If an error occurs return the negative error code and @ictx is left
 101  * untouched.
 102  *
 103  * When finished with the entry and its data, call ntfs_index_ctx_put() to free
 104  * the context and other associated resources.
 105  *
 106  * If the index entry was modified, call flush_dcache_index_entry_page()
 107  * immediately after the modification and either ntfs_index_entry_mark_dirty()
 108  * or ntfs_index_entry_write() before the call to ntfs_index_ctx_put() to
 109  * ensure that the changes are written to disk.
 110  *
 111  * Locking:  - Caller must hold i_mutex on the index inode.
 112  *           - Each page cache page in the index allocation mapping must be
 113  *             locked whilst being accessed otherwise we may find a corrupt
 114  *             page due to it being under ->writepage at the moment which
 115  *             applies the mst protection fixups before writing out and then
 116  *             removes them again after the write is complete after which it
 117  *             unlocks the page.
 118  */
 119 int ntfs_index_lookup(const void *key, const int key_len,
 120                 ntfs_index_context *ictx)
 121 {
 122         VCN vcn, old_vcn;
 123         ntfs_inode *idx_ni = ictx->idx_ni;
 124         ntfs_volume *vol = idx_ni->vol;
 125         struct super_block *sb = vol->sb;
 126         ntfs_inode *base_ni = idx_ni->ext.base_ntfs_ino;
 127         MFT_RECORD *m;
 128         INDEX_ROOT *ir;
 129         INDEX_ENTRY *ie;
 130         INDEX_ALLOCATION *ia;
 131         u8 *index_end, *kaddr;
 132         ntfs_attr_search_ctx *actx;
 133         struct address_space *ia_mapping;
 134         struct page *page;
 135         int rc, err = 0;
 136
 137         ntfs_debug("Entering.");
 138         BUG_ON(!NInoAttr(idx_ni));
 139         BUG_ON(idx_ni->type != AT_INDEX_ALLOCATION);
 140         BUG_ON(idx_ni->nr_extents != -1);
 141         BUG_ON(!base_ni);
 142         BUG_ON(!key);
 143         BUG_ON(key_len <= 0);
 144         if (!ntfs_is_collation_rule_supported(
 145                         idx_ni->itype.index.collation_rule)) {
 146                 ntfs_error(sb, "Index uses unsupported collation rule 0x%x.  "
 147                                 "Aborting lookup.", le32_to_cpu(
 148                                 idx_ni->itype.index.collation_rule));
 149                 return -EOPNOTSUPP;
 150         }
 151         /* Get hold of the mft record for the index inode. */
 152         m = map_mft_record(base_ni);
 153         if (IS_ERR(m)) {
 154                 ntfs_error(sb, "map_mft_record() failed with error code %ld.",
 155                                 -PTR_ERR(m));
 156                 return PTR_ERR(m);
 157         }
 158         actx = ntfs_attr_get_search_ctx(base_ni, m);
 159         if (unlikely(!actx)) {
 160                 err = -ENOMEM;
 161                 goto err_out;
 162         }
 163         /* Find the index root attribute in the mft record. */
 164         err = ntfs_attr_lookup(AT_INDEX_ROOT, idx_ni->name, idx_ni->name_len,
 165                         CASE_SENSITIVE, 0, NULL, 0, actx);
 166         if (unlikely(err)) {
 167                 if (err == -ENOENT) {
 168                         ntfs_error(sb, "Index root attribute missing in inode "
 169                                         "0x%lx.", idx_ni->mft_no);
 170                         err = -EIO;
 171                 }
 172                 goto err_out;
 173         }
 174         /* Get to the index root value (it has been verified in read_inode). */
 175         ir = (INDEX_ROOT*)((u8*)actx->attr +
 176                         le16_to_cpu(actx->attr->data.resident.value_offset));
 177         index_end = (u8*)&ir->index + le32_to_cpu(ir->index.index_length);
 178         /* The first index entry. */
 179         ie = (INDEX_ENTRY*)((u8*)&ir->index +
 180                         le32_to_cpu(ir->index.entries_offset));
 181         /*
 182          * Loop until we exceed valid memory (corruption case) or until we
 183          * reach the last entry.
 184          */
 185         for (;; ie = (INDEX_ENTRY*)((u8*)ie + le16_to_cpu(ie->length))) {
 186                 /* Bounds checks. */
 187                 if ((u8*)ie < (u8*)actx->mrec || (u8*)ie +
 188                                 sizeof(INDEX_ENTRY_HEADER) > index_end ||
 189                                 (u8*)ie + le16_to_cpu(ie->length) > index_end)
 190                         goto idx_err_out;
 191                 /*
 192                  * The last entry cannot contain a key.  It can however contain
 193                  * a pointer to a child node in the B+tree so we just break out.
 194                  */
 195                 if (ie->flags & INDEX_ENTRY_END)
 196                         break;
 197                 /* Further bounds checks. */
 198                 if ((u32)sizeof(INDEX_ENTRY_HEADER) +
 199                                 le16_to_cpu(ie->key_length) >
 200                                 le16_to_cpu(ie->data.vi.data_offset) ||
 201                                 (u32)le16_to_cpu(ie->data.vi.data_offset) +
 202                                 le16_to_cpu(ie->data.vi.data_length) >
 203                                 le16_to_cpu(ie->length))
 204                         goto idx_err_out;
 205                 /* If the keys match perfectly, we setup @ictx and return 0. */
 206                 if ((key_len == le16_to_cpu(ie->key_length)) && !memcmp(key,
 207                                 &ie->key, key_len)) {
 208 ir_done:
 209                         ictx->is_in_root = true;
 210                         ictx->ir = ir;
 211                         ictx->actx = actx;
 212                         ictx->base_ni = base_ni;
 213                         ictx->ia = NULL;
 214                         ictx->page = NULL;
 215 done:
 216                         ictx->entry = ie;
 217                         ictx->data = (u8*)ie +
 218                                         le16_to_cpu(ie->data.vi.data_offset);
 219                         ictx->data_len = le16_to_cpu(ie->data.vi.data_length);
 220                         ntfs_debug("Done.");
 221                         return err;
 222                 }
 223                 /*
 224                  * Not a perfect match, need to do full blown collation so we
 225                  * know which way in the B+tree we have to go.
 226                  */
 227                 rc = ntfs_collate(vol, idx_ni->itype.index.collation_rule, key,
 228                                 key_len, &ie->key, le16_to_cpu(ie->key_length));
 229                 /*
 230                  * If @key collates before the key of the current entry, there
 231                  * is definitely no such key in this index but we might need to
 232                  * descend into the B+tree so we just break out of the loop.
 233                  */
 234                 if (rc == -1)
 235                         break;
 236                 /*
 237                  * A match should never happen as the memcmp() call should have
 238                  * cought it, but we still treat it correctly.
 239                  */
 240                 if (!rc)
 241                         goto ir_done;
 242                 /* The keys are not equal, continue the search. */
 243         }
 244         /*
 245          * We have finished with this index without success.  Check for the
 246          * presence of a child node and if not present setup @ictx and return
 247          * -ENOENT.
 248          */
 249         if (!(ie->flags & INDEX_ENTRY_NODE)) {
 250                 ntfs_debug("Entry not found.");
 251                 err = -ENOENT;
 252                 goto ir_done;
 253         } /* Child node present, descend into it. */
 254         /* Consistency check: Verify that an index allocation exists. */
 255         if (!NInoIndexAllocPresent(idx_ni)) {
 256                 ntfs_error(sb, "No index allocation attribute but index entry "
 257                                 "requires one.  Inode 0x%lx is corrupt or "
 258                                 "driver bug.", idx_ni->mft_no);
 259                 goto err_out;
 260         }
 261         /* Get the starting vcn of the index_block holding the child node. */
 262         vcn = sle64_to_cpup((sle64*)((u8*)ie + le16_to_cpu(ie->length) - 8));
 263         ia_mapping = VFS_I(idx_ni)->i_mapping;
 264         /*
 265          * We are done with the index root and the mft record.  Release them,
 266          * otherwise we deadlock with ntfs_map_page().
 267          */
 268         ntfs_attr_put_search_ctx(actx);
 269         unmap_mft_record(base_ni);
 270         m = NULL;
 271         actx = NULL;
 272 descend_into_child_node:
 273         /*
 274          * Convert vcn to index into the index allocation attribute in units
 275          * of PAGE_CACHE_SIZE and map the page cache page, reading it from
 276          * disk if necessary.
 277          */
 278         page = ntfs_map_page(ia_mapping, vcn <<
 279                         idx_ni->itype.index.vcn_size_bits >> PAGE_CACHE_SHIFT);
 280         if (IS_ERR(page)) {
 281                 ntfs_error(sb, "Failed to map index page, error %ld.",
 282                                 -PTR_ERR(page));
 283                 err = PTR_ERR(page);
 284                 goto err_out;
 285         }
 286         lock_page(page);
 287         kaddr = (u8*)page_address(page);
 288 fast_descend_into_child_node:
 289         /* Get to the index allocation block. */
 290         ia = (INDEX_ALLOCATION*)(kaddr + ((vcn <<
 291                         idx_ni->itype.index.vcn_size_bits) & ~PAGE_CACHE_MASK));
 292         /* Bounds checks. */
 293         if ((u8*)ia < kaddr || (u8*)ia > kaddr + PAGE_CACHE_SIZE) {
 294                 ntfs_error(sb, "Out of bounds check failed.  Corrupt inode "
 295                                 "0x%lx or driver bug.", idx_ni->mft_no);
 296                 goto unm_err_out;
 297         }
 298         /* Catch multi sector transfer fixup errors. */
 299         if (unlikely(!ntfs_is_indx_record(ia->magic))) {
 300                 ntfs_error(sb, "Index record with vcn 0x%llx is corrupt.  "
 301                                 "Corrupt inode 0x%lx.  Run chkdsk.",
 302                                 (long long)vcn, idx_ni->mft_no);
 303                 goto unm_err_out;
 304         }
 305         if (sle64_to_cpu(ia->index_block_vcn) != vcn) {
 306                 ntfs_error(sb, "Actual VCN (0x%llx) of index buffer is "
 307                                 "different from expected VCN (0x%llx).  Inode "
 308                                 "0x%lx is corrupt or driver bug.",
 309                                 (unsigned long long)
 310                                 sle64_to_cpu(ia->index_block_vcn),
 311                                 (unsigned long long)vcn, idx_ni->mft_no);
 312                 goto unm_err_out;
 313         }
 314         if (le32_to_cpu(ia->index.allocated_size) + 0x18 !=
 315                         idx_ni->itype.index.block_size) {
 316                 ntfs_error(sb, "Index buffer (VCN 0x%llx) of inode 0x%lx has "
 317                                 "a size (%u) differing from the index "
 318                                 "specified size (%u).  Inode is corrupt or "
 319                                 "driver bug.", (unsigned long long)vcn,
 320                                 idx_ni->mft_no,
 321                                 le32_to_cpu(ia->index.allocated_size) + 0x18,
 322                                 idx_ni->itype.index.block_size);
 323                 goto unm_err_out;
 324         }
 325         index_end = (u8*)ia + idx_ni->itype.index.block_size;
 326         if (index_end > kaddr + PAGE_CACHE_SIZE) {
 327                 ntfs_error(sb, "Index buffer (VCN 0x%llx) of inode 0x%lx "
 328                                 "crosses page boundary.  Impossible!  Cannot "
 329                                 "access!  This is probably a bug in the "
 330                                 "driver.", (unsigned long long)vcn,
 331                                 idx_ni->mft_no);
 332                 goto unm_err_out;
 333         }
 334         index_end = (u8*)&ia->index + le32_to_cpu(ia->index.index_length);
 335         if (index_end > (u8*)ia + idx_ni->itype.index.block_size) {
 336                 ntfs_error(sb, "Size of index buffer (VCN 0x%llx) of inode "
 337                                 "0x%lx exceeds maximum size.",
 338                                 (unsigned long long)vcn, idx_ni->mft_no);
 339                 goto unm_err_out;
 340         }
 341         /* The first index entry. */
 342         ie = (INDEX_ENTRY*)((u8*)&ia->index +
 343                         le32_to_cpu(ia->index.entries_offset));
 344         /*
 345          * Iterate similar to above big loop but applied to index buffer, thus
 346          * loop until we exceed valid memory (corruption case) or until we
 347          * reach the last entry.
 348          */
 349         for (;; ie = (INDEX_ENTRY*)((u8*)ie + le16_to_cpu(ie->length))) {
 350                 /* Bounds checks. */
 351                 if ((u8*)ie < (u8*)ia || (u8*)ie +
 352                                 sizeof(INDEX_ENTRY_HEADER) > index_end ||
 353                                 (u8*)ie + le16_to_cpu(ie->length) > index_end) {
 354                         ntfs_error(sb, "Index entry out of bounds in inode "
 355                                         "0x%lx.", idx_ni->mft_no);
 356                         goto unm_err_out;
 357                 }
 358                 /*
 359                  * The last entry cannot contain a key.  It can however contain
 360                  * a pointer to a child node in the B+tree so we just break out.
 361                  */
 362                 if (ie->flags & INDEX_ENTRY_END)
 363                         break;
 364                 /* Further bounds checks. */
 365                 if ((u32)sizeof(INDEX_ENTRY_HEADER) +
 366                                 le16_to_cpu(ie->key_length) >
 367                                 le16_to_cpu(ie->data.vi.data_offset) ||
 368                                 (u32)le16_to_cpu(ie->data.vi.data_offset) +
 369                                 le16_to_cpu(ie->data.vi.data_length) >
 370                                 le16_to_cpu(ie->length)) {
 371                         ntfs_error(sb, "Index entry out of bounds in inode "
 372                                         "0x%lx.", idx_ni->mft_no);
 373                         goto unm_err_out;
 374                 }
 375                 /* If the keys match perfectly, we setup @ictx and return 0. */
 376                 if ((key_len == le16_to_cpu(ie->key_length)) && !memcmp(key,
 377                                 &ie->key, key_len)) {
 378 ia_done:
 379                         ictx->is_in_root = false;
 380                         ictx->actx = NULL;
 381                         ictx->base_ni = NULL;
 382                         ictx->ia = ia;
 383                         ictx->page = page;
 384                         goto done;
 385                 }
 386                 /*
 387                  * Not a perfect match, need to do full blown collation so we
 388                  * know which way in the B+tree we have to go.
 389                  */
 390                 rc = ntfs_collate(vol, idx_ni->itype.index.collation_rule, key,
 391                                 key_len, &ie->key, le16_to_cpu(ie->key_length));
 392                 /*
 393                  * If @key collates before the key of the current entry, there
 394                  * is definitely no such key in this index but we might need to
 395                  * descend into the B+tree so we just break out of the loop.
 396                  */
 397                 if (rc == -1)
 398                         break;
 399                 /*
 400                  * A match should never happen as the memcmp() call should have
 401                  * cought it, but we still treat it correctly.
 402                  */
 403                 if (!rc)
 404                         goto ia_done;
 405                 /* The keys are not equal, continue the search. */
 406         }
 407         /*
 408          * We have finished with this index buffer without success.  Check for
 409          * the presence of a child node and if not present return -ENOENT.
 410          */
 411         if (!(ie->flags & INDEX_ENTRY_NODE)) {
 412                 ntfs_debug("Entry not found.");
 413                 err = -ENOENT;
 414                 goto ia_done;
 415         }
 416         if ((ia->index.flags & NODE_MASK) == LEAF_NODE) {
 417                 ntfs_error(sb, "Index entry with child node found in a leaf "
 418                                 "node in inode 0x%lx.", idx_ni->mft_no);
 419                 goto unm_err_out;
 420         }
 421         /* Child node present, descend into it. */
 422         old_vcn = vcn;
 423         vcn = sle64_to_cpup((sle64*)((u8*)ie + le16_to_cpu(ie->length) - 8));
 424         if (vcn >= 0) {
 425                 /*
 426                  * If vcn is in the same page cache page as old_vcn we recycle
 427                  * the mapped page.
 428                  */
 429                 if (old_vcn << vol->cluster_size_bits >>
 430                                 PAGE_CACHE_SHIFT == vcn <<
 431                                 vol->cluster_size_bits >>
 432                                 PAGE_CACHE_SHIFT)
 433                         goto fast_descend_into_child_node;
 434                 unlock_page(page);
 435                 ntfs_unmap_page(page);
 436                 goto descend_into_child_node;
 437         }
 438         ntfs_error(sb, "Negative child node vcn in inode 0x%lx.",
 439                         idx_ni->mft_no);
 440 unm_err_out:
 441         unlock_page(page);
 442         ntfs_unmap_page(page);
 443 err_out:
 444         if (!err)
 445                 err = -EIO;
 446         if (actx)
 447                 ntfs_attr_put_search_ctx(actx);
 448         if (m)
 449                 unmap_mft_record(base_ni);
 450         return err;
 451 idx_err_out:
 452         ntfs_error(sb, "Corrupt index.  Aborting lookup.");
 453         goto err_out;
 454 }