fs/ntfs/index.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * index.c - NTFS kernel index handling.  Part of the Linux-NTFS project.
   4  *
   5  * Copyright (c) 2004-2005 Anton Altaparmakov
   6  */
   7
   8 #include <linux/slab.h>
   9
  10 #include "aops.h"
  11 #include "collate.h"
  12 #include "debug.h"
  13 #include "index.h"
  14 #include "ntfs.h"
  15
  16 /**
  17  * ntfs_index_ctx_get - allocate and initialize a new index context
  18  * @idx_ni:     ntfs index inode with which to initialize the context
  19  *
  20  * Allocate a new index context, initialize it with @idx_ni and return it.
  21  * Return NULL if allocation failed.
  22  *
  23  * Locking:  Caller must hold i_mutex on the index inode.
  24  */
  25 ntfs_index_context *ntfs_index_ctx_get(ntfs_inode *idx_ni)
  26 {
  27         ntfs_index_context *ictx;
  28
  29         ictx = kmem_cache_alloc(ntfs_index_ctx_cache, GFP_NOFS);
  30         if (ictx)
  31                 *ictx = (ntfs_index_context){ .idx_ni = idx_ni };
  32         return ictx;
  33 }
  34
  35 /**
  36  * ntfs_index_ctx_put - release an index context
  37  * @ictx:       index context to free
  38  *
  39  * Release the index context @ictx, releasing all associated resources.
  40  *
  41  * Locking:  Caller must hold i_mutex on the index inode.
  42  */
  43 void ntfs_index_ctx_put(ntfs_index_context *ictx)
  44 {
  45         if (ictx->entry) {
  46                 if (ictx->is_in_root) {
  47                         if (ictx->actx)
  48                                 ntfs_attr_put_search_ctx(ictx->actx);
  49                         if (ictx->base_ni)
  50                                 unmap_mft_record(ictx->base_ni);
  51                 } else {
  52                         struct page *page = ictx->page;
  53                         if (page) {
  54                                 BUG_ON(!PageLocked(page));
  55                                 unlock_page(page);
  56                                 ntfs_unmap_page(page);
  57                         }
  58                 }
  59         }
  60         kmem_cache_free(ntfs_index_ctx_cache, ictx);
  61         return;
  62 }
  63
  64 /**
  65  * ntfs_index_lookup - find a key in an index and return its index entry
  66  * @key:        [IN] key for which to search in the index
  67  * @key_len:    [IN] length of @key in bytes
  68  * @ictx:       [IN/OUT] context describing the index and the returned entry
  69  *
  70  * Before calling ntfs_index_lookup(), @ictx must have been obtained from a
  71  * call to ntfs_index_ctx_get().
  72  *
  73  * Look for the @key in the index specified by the index lookup context @ictx.
  74  * ntfs_index_lookup() walks the contents of the index looking for the @key.
  75  *
  76  * If the @key is found in the index, 0 is returned and @ictx is setup to
  77  * describe the index entry containing the matching @key.  @ictx->entry is the
  78  * index entry and @ictx->data and @ictx->data_len are the index entry data and
  79  * its length in bytes, respectively.
  80  *
  81  * If the @key is not found in the index, -ENOENT is returned and @ictx is
  82  * setup to describe the index entry whose key collates immediately after the
  83  * search @key, i.e. this is the position in the index at which an index entry
  84  * with a key of @key would need to be inserted.
  85  *
  86  * If an error occurs return the negative error code and @ictx is left
  87  * untouched.
  88  *
  89  * When finished with the entry and its data, call ntfs_index_ctx_put() to free
  90  * the context and other associated resources.
  91  *
  92  * If the index entry was modified, call flush_dcache_index_entry_page()
  93  * immediately after the modification and either ntfs_index_entry_mark_dirty()
  94  * or ntfs_index_entry_write() before the call to ntfs_index_ctx_put() to
  95  * ensure that the changes are written to disk.
  96  *
  97  * Locking:  - Caller must hold i_mutex on the index inode.
  98  *           - Each page cache page in the index allocation mapping must be
  99  *             locked whilst being accessed otherwise we may find a corrupt
 100  *             page due to it being under ->writepage at the moment which
 101  *             applies the mst protection fixups before writing out and then
 102  *             removes them again after the write is complete after which it
 103  *             unlocks the page.
 104  */
 105 int ntfs_index_lookup(const void *key, const int key_len,
 106                 ntfs_index_context *ictx)
 107 {
 108         VCN vcn, old_vcn;
 109         ntfs_inode *idx_ni = ictx->idx_ni;
 110         ntfs_volume *vol = idx_ni->vol;
 111         struct super_block *sb = vol->sb;
 112         ntfs_inode *base_ni = idx_ni->ext.base_ntfs_ino;
 113         MFT_RECORD *m;
 114         INDEX_ROOT *ir;
 115         INDEX_ENTRY *ie;
 116         INDEX_ALLOCATION *ia;
 117         u8 *index_end, *kaddr;
 118         ntfs_attr_search_ctx *actx;
 119         struct address_space *ia_mapping;
 120         struct page *page;
 121         int rc, err = 0;
 122
 123         ntfs_debug("Entering.");
 124         BUG_ON(!NInoAttr(idx_ni));
 125         BUG_ON(idx_ni->type != AT_INDEX_ALLOCATION);
 126         BUG_ON(idx_ni->nr_extents != -1);
 127         BUG_ON(!base_ni);
 128         BUG_ON(!key);
 129         BUG_ON(key_len <= 0);
 130         if (!ntfs_is_collation_rule_supported(
 131                         idx_ni->itype.index.collation_rule)) {
 132                 ntfs_error(sb, "Index uses unsupported collation rule 0x%x.  "
 133                                 "Aborting lookup.", le32_to_cpu(
 134                                 idx_ni->itype.index.collation_rule));
 135                 return -EOPNOTSUPP;
 136         }
 137         /* Get hold of the mft record for the index inode. */
 138         m = map_mft_record(base_ni);
 139         if (IS_ERR(m)) {
 140                 ntfs_error(sb, "map_mft_record() failed with error code %ld.",
 141                                 -PTR_ERR(m));
 142                 return PTR_ERR(m);
 143         }
 144         actx = ntfs_attr_get_search_ctx(base_ni, m);
 145         if (unlikely(!actx)) {
 146                 err = -ENOMEM;
 147                 goto err_out;
 148         }
 149         /* Find the index root attribute in the mft record. */
 150         err = ntfs_attr_lookup(AT_INDEX_ROOT, idx_ni->name, idx_ni->name_len,
 151                         CASE_SENSITIVE, 0, NULL, 0, actx);
 152         if (unlikely(err)) {
 153                 if (err == -ENOENT) {
 154                         ntfs_error(sb, "Index root attribute missing in inode "
 155                                         "0x%lx.", idx_ni->mft_no);
 156                         err = -EIO;
 157                 }
 158                 goto err_out;
 159         }
 160         /* Get to the index root value (it has been verified in read_inode). */
 161         ir = (INDEX_ROOT*)((u8*)actx->attr +
 162                         le16_to_cpu(actx->attr->data.resident.value_offset));
 163         index_end = (u8*)&ir->index + le32_to_cpu(ir->index.index_length);
 164         /* The first index entry. */
 165         ie = (INDEX_ENTRY*)((u8*)&ir->index +
 166                         le32_to_cpu(ir->index.entries_offset));
 167         /*
 168          * Loop until we exceed valid memory (corruption case) or until we
 169          * reach the last entry.
 170          */
 171         for (;; ie = (INDEX_ENTRY*)((u8*)ie + le16_to_cpu(ie->length))) {
 172                 /* Bounds checks. */
 173                 if ((u8*)ie < (u8*)actx->mrec || (u8*)ie +
 174                                 sizeof(INDEX_ENTRY_HEADER) > index_end ||
 175                                 (u8*)ie + le16_to_cpu(ie->length) > index_end)
 176                         goto idx_err_out;
 177                 /*
 178                  * The last entry cannot contain a key.  It can however contain
 179                  * a pointer to a child node in the B+tree so we just break out.
 180                  */
 181                 if (ie->flags & INDEX_ENTRY_END)
 182                         break;
 183                 /* Further bounds checks. */
 184                 if ((u32)sizeof(INDEX_ENTRY_HEADER) +
 185                                 le16_to_cpu(ie->key_length) >
 186                                 le16_to_cpu(ie->data.vi.data_offset) ||
 187                                 (u32)le16_to_cpu(ie->data.vi.data_offset) +
 188                                 le16_to_cpu(ie->data.vi.data_length) >
 189                                 le16_to_cpu(ie->length))
 190                         goto idx_err_out;
 191                 /* If the keys match perfectly, we setup @ictx and return 0. */
 192                 if ((key_len == le16_to_cpu(ie->key_length)) && !memcmp(key,
 193                                 &ie->key, key_len)) {
 194 ir_done:
 195                         ictx->is_in_root = true;
 196                         ictx->ir = ir;
 197                         ictx->actx = actx;
 198                         ictx->base_ni = base_ni;
 199                         ictx->ia = NULL;
 200                         ictx->page = NULL;
 201 done:
 202                         ictx->entry = ie;
 203                         ictx->data = (u8*)ie +
 204                                         le16_to_cpu(ie->data.vi.data_offset);
 205                         ictx->data_len = le16_to_cpu(ie->data.vi.data_length);
 206                         ntfs_debug("Done.");
 207                         return err;
 208                 }
 209                 /*
 210                  * Not a perfect match, need to do full blown collation so we
 211                  * know which way in the B+tree we have to go.
 212                  */
 213                 rc = ntfs_collate(vol, idx_ni->itype.index.collation_rule, key,
 214                                 key_len, &ie->key, le16_to_cpu(ie->key_length));
 215                 /*
 216                  * If @key collates before the key of the current entry, there
 217                  * is definitely no such key in this index but we might need to
 218                  * descend into the B+tree so we just break out of the loop.
 219                  */
 220                 if (rc == -1)
 221                         break;
 222                 /*
 223                  * A match should never happen as the memcmp() call should have
 224                  * cought it, but we still treat it correctly.
 225                  */
 226                 if (!rc)
 227                         goto ir_done;
 228                 /* The keys are not equal, continue the search. */
 229         }
 230         /*
 231          * We have finished with this index without success.  Check for the
 232          * presence of a child node and if not present setup @ictx and return
 233          * -ENOENT.
 234          */
 235         if (!(ie->flags & INDEX_ENTRY_NODE)) {
 236                 ntfs_debug("Entry not found.");
 237                 err = -ENOENT;
 238                 goto ir_done;
 239         } /* Child node present, descend into it. */
 240         /* Consistency check: Verify that an index allocation exists. */
 241         if (!NInoIndexAllocPresent(idx_ni)) {
 242                 ntfs_error(sb, "No index allocation attribute but index entry "
 243                                 "requires one.  Inode 0x%lx is corrupt or "
 244                                 "driver bug.", idx_ni->mft_no);
 245                 goto err_out;
 246         }
 247         /* Get the starting vcn of the index_block holding the child node. */
 248         vcn = sle64_to_cpup((sle64*)((u8*)ie + le16_to_cpu(ie->length) - 8));
 249         ia_mapping = VFS_I(idx_ni)->i_mapping;
 250         /*
 251          * We are done with the index root and the mft record.  Release them,
 252          * otherwise we deadlock with ntfs_map_page().
 253          */
 254         ntfs_attr_put_search_ctx(actx);
 255         unmap_mft_record(base_ni);
 256         m = NULL;
 257         actx = NULL;
 258 descend_into_child_node:
 259         /*
 260          * Convert vcn to index into the index allocation attribute in units
 261          * of PAGE_SIZE and map the page cache page, reading it from
 262          * disk if necessary.
 263          */
 264         page = ntfs_map_page(ia_mapping, vcn <<
 265                         idx_ni->itype.index.vcn_size_bits >> PAGE_SHIFT);
 266         if (IS_ERR(page)) {
 267                 ntfs_error(sb, "Failed to map index page, error %ld.",
 268                                 -PTR_ERR(page));
 269                 err = PTR_ERR(page);
 270                 goto err_out;
 271         }
 272         lock_page(page);
 273         kaddr = (u8*)page_address(page);
 274 fast_descend_into_child_node:
 275         /* Get to the index allocation block. */
 276         ia = (INDEX_ALLOCATION*)(kaddr + ((vcn <<
 277                         idx_ni->itype.index.vcn_size_bits) & ~PAGE_MASK));
 278         /* Bounds checks. */
 279         if ((u8*)ia < kaddr || (u8*)ia > kaddr + PAGE_SIZE) {
 280                 ntfs_error(sb, "Out of bounds check failed.  Corrupt inode "
 281                                 "0x%lx or driver bug.", idx_ni->mft_no);
 282                 goto unm_err_out;
 283         }
 284         /* Catch multi sector transfer fixup errors. */
 285         if (unlikely(!ntfs_is_indx_record(ia->magic))) {
 286                 ntfs_error(sb, "Index record with vcn 0x%llx is corrupt.  "
 287                                 "Corrupt inode 0x%lx.  Run chkdsk.",
 288                                 (long long)vcn, idx_ni->mft_no);
 289                 goto unm_err_out;
 290         }
 291         if (sle64_to_cpu(ia->index_block_vcn) != vcn) {
 292                 ntfs_error(sb, "Actual VCN (0x%llx) of index buffer is "
 293                                 "different from expected VCN (0x%llx).  Inode "
 294                                 "0x%lx is corrupt or driver bug.",
 295                                 (unsigned long long)
 296                                 sle64_to_cpu(ia->index_block_vcn),
 297                                 (unsigned long long)vcn, idx_ni->mft_no);
 298                 goto unm_err_out;
 299         }
 300         if (le32_to_cpu(ia->index.allocated_size) + 0x18 !=
 301                         idx_ni->itype.index.block_size) {
 302                 ntfs_error(sb, "Index buffer (VCN 0x%llx) of inode 0x%lx has "
 303                                 "a size (%u) differing from the index "
 304                                 "specified size (%u).  Inode is corrupt or "
 305                                 "driver bug.", (unsigned long long)vcn,
 306                                 idx_ni->mft_no,
 307                                 le32_to_cpu(ia->index.allocated_size) + 0x18,
 308                                 idx_ni->itype.index.block_size);
 309                 goto unm_err_out;
 310         }
 311         index_end = (u8*)ia + idx_ni->itype.index.block_size;
 312         if (index_end > kaddr + PAGE_SIZE) {
 313                 ntfs_error(sb, "Index buffer (VCN 0x%llx) of inode 0x%lx "
 314                                 "crosses page boundary.  Impossible!  Cannot "
 315                                 "access!  This is probably a bug in the "
 316                                 "driver.", (unsigned long long)vcn,
 317                                 idx_ni->mft_no);
 318                 goto unm_err_out;
 319         }
 320         index_end = (u8*)&ia->index + le32_to_cpu(ia->index.index_length);
 321         if (index_end > (u8*)ia + idx_ni->itype.index.block_size) {
 322                 ntfs_error(sb, "Size of index buffer (VCN 0x%llx) of inode "
 323                                 "0x%lx exceeds maximum size.",
 324                                 (unsigned long long)vcn, idx_ni->mft_no);
 325                 goto unm_err_out;
 326         }
 327         /* The first index entry. */
 328         ie = (INDEX_ENTRY*)((u8*)&ia->index +
 329                         le32_to_cpu(ia->index.entries_offset));
 330         /*
 331          * Iterate similar to above big loop but applied to index buffer, thus
 332          * loop until we exceed valid memory (corruption case) or until we
 333          * reach the last entry.
 334          */
 335         for (;; ie = (INDEX_ENTRY*)((u8*)ie + le16_to_cpu(ie->length))) {
 336                 /* Bounds checks. */
 337                 if ((u8*)ie < (u8*)ia || (u8*)ie +
 338                                 sizeof(INDEX_ENTRY_HEADER) > index_end ||
 339                                 (u8*)ie + le16_to_cpu(ie->length) > index_end) {
 340                         ntfs_error(sb, "Index entry out of bounds in inode "
 341                                         "0x%lx.", idx_ni->mft_no);
 342                         goto unm_err_out;
 343                 }
 344                 /*
 345                  * The last entry cannot contain a key.  It can however contain
 346                  * a pointer to a child node in the B+tree so we just break out.
 347                  */
 348                 if (ie->flags & INDEX_ENTRY_END)
 349                         break;
 350                 /* Further bounds checks. */
 351                 if ((u32)sizeof(INDEX_ENTRY_HEADER) +
 352                                 le16_to_cpu(ie->key_length) >
 353                                 le16_to_cpu(ie->data.vi.data_offset) ||
 354                                 (u32)le16_to_cpu(ie->data.vi.data_offset) +
 355                                 le16_to_cpu(ie->data.vi.data_length) >
 356                                 le16_to_cpu(ie->length)) {
 357                         ntfs_error(sb, "Index entry out of bounds in inode "
 358                                         "0x%lx.", idx_ni->mft_no);
 359                         goto unm_err_out;
 360                 }
 361                 /* If the keys match perfectly, we setup @ictx and return 0. */
 362                 if ((key_len == le16_to_cpu(ie->key_length)) && !memcmp(key,
 363                                 &ie->key, key_len)) {
 364 ia_done:
 365                         ictx->is_in_root = false;
 366                         ictx->actx = NULL;
 367                         ictx->base_ni = NULL;
 368                         ictx->ia = ia;
 369                         ictx->page = page;
 370                         goto done;
 371                 }
 372                 /*
 373                  * Not a perfect match, need to do full blown collation so we
 374                  * know which way in the B+tree we have to go.
 375                  */
 376                 rc = ntfs_collate(vol, idx_ni->itype.index.collation_rule, key,
 377                                 key_len, &ie->key, le16_to_cpu(ie->key_length));
 378                 /*
 379                  * If @key collates before the key of the current entry, there
 380                  * is definitely no such key in this index but we might need to
 381                  * descend into the B+tree so we just break out of the loop.
 382                  */
 383                 if (rc == -1)
 384                         break;
 385                 /*
 386                  * A match should never happen as the memcmp() call should have
 387                  * cought it, but we still treat it correctly.
 388                  */
 389                 if (!rc)
 390                         goto ia_done;
 391                 /* The keys are not equal, continue the search. */
 392         }
 393         /*
 394          * We have finished with this index buffer without success.  Check for
 395          * the presence of a child node and if not present return -ENOENT.
 396          */
 397         if (!(ie->flags & INDEX_ENTRY_NODE)) {
 398                 ntfs_debug("Entry not found.");
 399                 err = -ENOENT;
 400                 goto ia_done;
 401         }
 402         if ((ia->index.flags & NODE_MASK) == LEAF_NODE) {
 403                 ntfs_error(sb, "Index entry with child node found in a leaf "
 404                                 "node in inode 0x%lx.", idx_ni->mft_no);
 405                 goto unm_err_out;
 406         }
 407         /* Child node present, descend into it. */
 408         old_vcn = vcn;
 409         vcn = sle64_to_cpup((sle64*)((u8*)ie + le16_to_cpu(ie->length) - 8));
 410         if (vcn >= 0) {
 411                 /*
 412                  * If vcn is in the same page cache page as old_vcn we recycle
 413                  * the mapped page.
 414                  */
 415                 if (old_vcn << vol->cluster_size_bits >>
 416                                 PAGE_SHIFT == vcn <<
 417                                 vol->cluster_size_bits >>
 418                                 PAGE_SHIFT)
 419                         goto fast_descend_into_child_node;
 420                 unlock_page(page);
 421                 ntfs_unmap_page(page);
 422                 goto descend_into_child_node;
 423         }
 424         ntfs_error(sb, "Negative child node vcn in inode 0x%lx.",
 425                         idx_ni->mft_no);
 426 unm_err_out:
 427         unlock_page(page);
 428         ntfs_unmap_page(page);
 429 err_out:
 430         if (!err)
 431                 err = -EIO;
 432         if (actx)
 433                 ntfs_attr_put_search_ctx(actx);
 434         if (m)
 435                 unmap_mft_record(base_ni);
 436         return err;
 437 idx_err_out:
 438         ntfs_error(sb, "Corrupt index.  Aborting lookup.");
 439         goto err_out;
 440 }