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_mutex 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, GFP_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_mutex 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_mutex 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->ir = ir;
 209                         ictx->actx = actx;
 210                         ictx->base_ni = base_ni;
 211                         ictx->ia = NULL;
 212                         ictx->page = NULL;
 213 done:
 214                         ictx->entry = ie;
 215                         ictx->data = (u8*)ie +
 216                                         le16_to_cpu(ie->data.vi.data_offset);
 217                         ictx->data_len = le16_to_cpu(ie->data.vi.data_length);
 218                         ntfs_debug("Done.");
 219                         return err;
 220                 }
 221                 /*
 222                  * Not a perfect match, need to do full blown collation so we
 223                  * know which way in the B+tree we have to go.
 224                  */
 225                 rc = ntfs_collate(vol, idx_ni->itype.index.collation_rule, key,
 226                                 key_len, &ie->key, le16_to_cpu(ie->key_length));
 227                 /*
 228                  * If @key collates before the key of the current entry, there
 229                  * is definitely no such key in this index but we might need to
 230                  * descend into the B+tree so we just break out of the loop.
 231                  */
 232                 if (rc == -1)
 233                         break;
 234                 /*
 235                  * A match should never happen as the memcmp() call should have
 236                  * cought it, but we still treat it correctly.
 237                  */
 238                 if (!rc)
 239                         goto ir_done;
 240                 /* The keys are not equal, continue the search. */
 241         }
 242         /*
 243          * We have finished with this index without success.  Check for the
 244          * presence of a child node and if not present setup @ictx and return
 245          * -ENOENT.
 246          */
 247         if (!(ie->flags & INDEX_ENTRY_NODE)) {
 248                 ntfs_debug("Entry not found.");
 249                 err = -ENOENT;
 250                 goto ir_done;
 251         } /* Child node present, descend into it. */
 252         /* Consistency check: Verify that an index allocation exists. */
 253         if (!NInoIndexAllocPresent(idx_ni)) {
 254                 ntfs_error(sb, "No index allocation attribute but index entry "
 255                                 "requires one.  Inode 0x%lx is corrupt or "
 256                                 "driver bug.", idx_ni->mft_no);
 257                 goto err_out;
 258         }
 259         /* Get the starting vcn of the index_block holding the child node. */
 260         vcn = sle64_to_cpup((sle64*)((u8*)ie + le16_to_cpu(ie->length) - 8));
 261         ia_mapping = VFS_I(idx_ni)->i_mapping;
 262         /*
 263          * We are done with the index root and the mft record.  Release them,
 264          * otherwise we deadlock with ntfs_map_page().
 265          */
 266         ntfs_attr_put_search_ctx(actx);
 267         unmap_mft_record(base_ni);
 268         m = NULL;
 269         actx = NULL;
 270 descend_into_child_node:
 271         /*
 272          * Convert vcn to index into the index allocation attribute in units
 273          * of PAGE_CACHE_SIZE and map the page cache page, reading it from
 274          * disk if necessary.
 275          */
 276         page = ntfs_map_page(ia_mapping, vcn <<
 277                         idx_ni->itype.index.vcn_size_bits >> PAGE_CACHE_SHIFT);
 278         if (IS_ERR(page)) {
 279                 ntfs_error(sb, "Failed to map index page, error %ld.",
 280                                 -PTR_ERR(page));
 281                 err = PTR_ERR(page);
 282                 goto err_out;
 283         }
 284         lock_page(page);
 285         kaddr = (u8*)page_address(page);
 286 fast_descend_into_child_node:
 287         /* Get to the index allocation block. */
 288         ia = (INDEX_ALLOCATION*)(kaddr + ((vcn <<
 289                         idx_ni->itype.index.vcn_size_bits) & ~PAGE_CACHE_MASK));
 290         /* Bounds checks. */
 291         if ((u8*)ia < kaddr || (u8*)ia > kaddr + PAGE_CACHE_SIZE) {
 292                 ntfs_error(sb, "Out of bounds check failed.  Corrupt inode "
 293                                 "0x%lx or driver bug.", idx_ni->mft_no);
 294                 goto unm_err_out;
 295         }
 296         /* Catch multi sector transfer fixup errors. */
 297         if (unlikely(!ntfs_is_indx_record(ia->magic))) {
 298                 ntfs_error(sb, "Index record with vcn 0x%llx is corrupt.  "
 299                                 "Corrupt inode 0x%lx.  Run chkdsk.",
 300                                 (long long)vcn, idx_ni->mft_no);
 301                 goto unm_err_out;
 302         }
 303         if (sle64_to_cpu(ia->index_block_vcn) != vcn) {
 304                 ntfs_error(sb, "Actual VCN (0x%llx) of index buffer is "
 305                                 "different from expected VCN (0x%llx).  Inode "
 306                                 "0x%lx is corrupt or driver bug.",
 307                                 (unsigned long long)
 308                                 sle64_to_cpu(ia->index_block_vcn),
 309                                 (unsigned long long)vcn, idx_ni->mft_no);
 310                 goto unm_err_out;
 311         }
 312         if (le32_to_cpu(ia->index.allocated_size) + 0x18 !=
 313                         idx_ni->itype.index.block_size) {
 314                 ntfs_error(sb, "Index buffer (VCN 0x%llx) of inode 0x%lx has "
 315                                 "a size (%u) differing from the index "
 316                                 "specified size (%u).  Inode is corrupt or "
 317                                 "driver bug.", (unsigned long long)vcn,
 318                                 idx_ni->mft_no,
 319                                 le32_to_cpu(ia->index.allocated_size) + 0x18,
 320                                 idx_ni->itype.index.block_size);
 321                 goto unm_err_out;
 322         }
 323         index_end = (u8*)ia + idx_ni->itype.index.block_size;
 324         if (index_end > kaddr + PAGE_CACHE_SIZE) {
 325                 ntfs_error(sb, "Index buffer (VCN 0x%llx) of inode 0x%lx "
 326                                 "crosses page boundary.  Impossible!  Cannot "
 327                                 "access!  This is probably a bug in the "
 328                                 "driver.", (unsigned long long)vcn,
 329                                 idx_ni->mft_no);
 330                 goto unm_err_out;
 331         }
 332         index_end = (u8*)&ia->index + le32_to_cpu(ia->index.index_length);
 333         if (index_end > (u8*)ia + idx_ni->itype.index.block_size) {
 334                 ntfs_error(sb, "Size of index buffer (VCN 0x%llx) of inode "
 335                                 "0x%lx exceeds maximum size.",
 336                                 (unsigned long long)vcn, idx_ni->mft_no);
 337                 goto unm_err_out;
 338         }
 339         /* The first index entry. */
 340         ie = (INDEX_ENTRY*)((u8*)&ia->index +
 341                         le32_to_cpu(ia->index.entries_offset));
 342         /*
 343          * Iterate similar to above big loop but applied to index buffer, thus
 344          * loop until we exceed valid memory (corruption case) or until we
 345          * reach the last entry.
 346          */
 347         for (;; ie = (INDEX_ENTRY*)((u8*)ie + le16_to_cpu(ie->length))) {
 348                 /* Bounds checks. */
 349                 if ((u8*)ie < (u8*)ia || (u8*)ie +
 350                                 sizeof(INDEX_ENTRY_HEADER) > index_end ||
 351                                 (u8*)ie + le16_to_cpu(ie->length) > index_end) {
 352                         ntfs_error(sb, "Index entry out of bounds in inode "
 353                                         "0x%lx.", idx_ni->mft_no);
 354                         goto unm_err_out;
 355                 }
 356                 /*
 357                  * The last entry cannot contain a key.  It can however contain
 358                  * a pointer to a child node in the B+tree so we just break out.
 359                  */
 360                 if (ie->flags & INDEX_ENTRY_END)
 361                         break;
 362                 /* Further bounds checks. */
 363                 if ((u32)sizeof(INDEX_ENTRY_HEADER) +
 364                                 le16_to_cpu(ie->key_length) >
 365                                 le16_to_cpu(ie->data.vi.data_offset) ||
 366                                 (u32)le16_to_cpu(ie->data.vi.data_offset) +
 367                                 le16_to_cpu(ie->data.vi.data_length) >
 368                                 le16_to_cpu(ie->length)) {
 369                         ntfs_error(sb, "Index entry out of bounds in inode "
 370                                         "0x%lx.", idx_ni->mft_no);
 371                         goto unm_err_out;
 372                 }
 373                 /* If the keys match perfectly, we setup @ictx and return 0. */
 374                 if ((key_len == le16_to_cpu(ie->key_length)) && !memcmp(key,
 375                                 &ie->key, key_len)) {
 376 ia_done:
 377                         ictx->is_in_root = false;
 378                         ictx->actx = NULL;
 379                         ictx->base_ni = NULL;
 380                         ictx->ia = ia;
 381                         ictx->page = page;
 382                         goto done;
 383                 }
 384                 /*
 385                  * Not a perfect match, need to do full blown collation so we
 386                  * know which way in the B+tree we have to go.
 387                  */
 388                 rc = ntfs_collate(vol, idx_ni->itype.index.collation_rule, key,
 389                                 key_len, &ie->key, le16_to_cpu(ie->key_length));
 390                 /*
 391                  * If @key collates before the key of the current entry, there
 392                  * is definitely no such key in this index but we might need to
 393                  * descend into the B+tree so we just break out of the loop.
 394                  */
 395                 if (rc == -1)
 396                         break;
 397                 /*
 398                  * A match should never happen as the memcmp() call should have
 399                  * cought it, but we still treat it correctly.
 400                  */
 401                 if (!rc)
 402                         goto ia_done;
 403                 /* The keys are not equal, continue the search. */
 404         }
 405         /*
 406          * We have finished with this index buffer without success.  Check for
 407          * the presence of a child node and if not present return -ENOENT.
 408          */
 409         if (!(ie->flags & INDEX_ENTRY_NODE)) {
 410                 ntfs_debug("Entry not found.");
 411                 err = -ENOENT;
 412                 goto ia_done;
 413         }
 414         if ((ia->index.flags & NODE_MASK) == LEAF_NODE) {
 415                 ntfs_error(sb, "Index entry with child node found in a leaf "
 416                                 "node in inode 0x%lx.", idx_ni->mft_no);
 417                 goto unm_err_out;
 418         }
 419         /* Child node present, descend into it. */
 420         old_vcn = vcn;
 421         vcn = sle64_to_cpup((sle64*)((u8*)ie + le16_to_cpu(ie->length) - 8));
 422         if (vcn >= 0) {
 423                 /*
 424                  * If vcn is in the same page cache page as old_vcn we recycle
 425                  * the mapped page.
 426                  */
 427                 if (old_vcn << vol->cluster_size_bits >>
 428                                 PAGE_CACHE_SHIFT == vcn <<
 429                                 vol->cluster_size_bits >>
 430                                 PAGE_CACHE_SHIFT)
 431                         goto fast_descend_into_child_node;
 432                 unlock_page(page);
 433                 ntfs_unmap_page(page);
 434                 goto descend_into_child_node;
 435         }
 436         ntfs_error(sb, "Negative child node vcn in inode 0x%lx.",
 437                         idx_ni->mft_no);
 438 unm_err_out:
 439         unlock_page(page);
 440         ntfs_unmap_page(page);
 441 err_out:
 442         if (!err)
 443                 err = -EIO;
 444         if (actx)
 445                 ntfs_attr_put_search_ctx(actx);
 446         if (m)
 447                 unmap_mft_record(base_ni);
 448         return err;
 449 idx_err_out:
 450         ntfs_error(sb, "Corrupt index.  Aborting lookup.");
 451         goto err_out;
 452 }