| /* |
| * index.c - NTFS kernel index handling. Part of the Linux-NTFS project. |
| * |
| * Copyright (c) 2004-2005 Anton Altaparmakov |
| * |
| * This program/include file is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU General Public License as published |
| * by the Free Software Foundation; either version 2 of the License, or |
| * (at your option) any later version. |
| * |
| * This program/include file is distributed in the hope that it will be |
| * useful, but WITHOUT ANY WARRANTY; without even the implied warranty |
| * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| * GNU General Public License for more details. |
| * |
| * You should have received a copy of the GNU General Public License |
| * along with this program (in the main directory of the Linux-NTFS |
| * distribution in the file COPYING); if not, write to the Free Software |
| * Foundation,Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
| */ |
| |
| #include "aops.h" |
| #include "collate.h" |
| #include "debug.h" |
| #include "index.h" |
| #include "ntfs.h" |
| |
| /** |
| * ntfs_index_ctx_get - allocate and initialize a new index context |
| * @idx_ni: ntfs index inode with which to initialize the context |
| * |
| * Allocate a new index context, initialize it with @idx_ni and return it. |
| * Return NULL if allocation failed. |
| * |
| * Locking: Caller must hold i_sem on the index inode. |
| */ |
| ntfs_index_context *ntfs_index_ctx_get(ntfs_inode *idx_ni) |
| { |
| ntfs_index_context *ictx; |
| |
| ictx = kmem_cache_alloc(ntfs_index_ctx_cache, SLAB_NOFS); |
| if (ictx) |
| *ictx = (ntfs_index_context){ .idx_ni = idx_ni }; |
| return ictx; |
| } |
| |
| /** |
| * ntfs_index_ctx_put - release an index context |
| * @ictx: index context to free |
| * |
| * Release the index context @ictx, releasing all associated resources. |
| * |
| * Locking: Caller must hold i_sem on the index inode. |
| */ |
| void ntfs_index_ctx_put(ntfs_index_context *ictx) |
| { |
| if (ictx->entry) { |
| if (ictx->is_in_root) { |
| if (ictx->actx) |
| ntfs_attr_put_search_ctx(ictx->actx); |
| if (ictx->base_ni) |
| unmap_mft_record(ictx->base_ni); |
| } else { |
| struct page *page = ictx->page; |
| if (page) { |
| BUG_ON(!PageLocked(page)); |
| unlock_page(page); |
| ntfs_unmap_page(page); |
| } |
| } |
| } |
| kmem_cache_free(ntfs_index_ctx_cache, ictx); |
| return; |
| } |
| |
| /** |
| * ntfs_index_lookup - find a key in an index and return its index entry |
| * @key: [IN] key for which to search in the index |
| * @key_len: [IN] length of @key in bytes |
| * @ictx: [IN/OUT] context describing the index and the returned entry |
| * |
| * Before calling ntfs_index_lookup(), @ictx must have been obtained from a |
| * call to ntfs_index_ctx_get(). |
| * |
| * Look for the @key in the index specified by the index lookup context @ictx. |
| * ntfs_index_lookup() walks the contents of the index looking for the @key. |
| * |
| * If the @key is found in the index, 0 is returned and @ictx is setup to |
| * describe the index entry containing the matching @key. @ictx->entry is the |
| * index entry and @ictx->data and @ictx->data_len are the index entry data and |
| * its length in bytes, respectively. |
| * |
| * If the @key is not found in the index, -ENOENT is returned and @ictx is |
| * setup to describe the index entry whose key collates immediately after the |
| * search @key, i.e. this is the position in the index at which an index entry |
| * with a key of @key would need to be inserted. |
| * |
| * If an error occurs return the negative error code and @ictx is left |
| * untouched. |
| * |
| * When finished with the entry and its data, call ntfs_index_ctx_put() to free |
| * the context and other associated resources. |
| * |
| * If the index entry was modified, call flush_dcache_index_entry_page() |
| * immediately after the modification and either ntfs_index_entry_mark_dirty() |
| * or ntfs_index_entry_write() before the call to ntfs_index_ctx_put() to |
| * ensure that the changes are written to disk. |
| * |
| * Locking: - Caller must hold i_sem on the index inode. |
| * - Each page cache page in the index allocation mapping must be |
| * locked whilst being accessed otherwise we may find a corrupt |
| * page due to it being under ->writepage at the moment which |
| * applies the mst protection fixups before writing out and then |
| * removes them again after the write is complete after which it |
| * unlocks the page. |
| */ |
| int ntfs_index_lookup(const void *key, const int key_len, |
| ntfs_index_context *ictx) |
| { |
| VCN vcn, old_vcn; |
| ntfs_inode *idx_ni = ictx->idx_ni; |
| ntfs_volume *vol = idx_ni->vol; |
| struct super_block *sb = vol->sb; |
| ntfs_inode *base_ni = idx_ni->ext.base_ntfs_ino; |
| MFT_RECORD *m; |
| INDEX_ROOT *ir; |
| INDEX_ENTRY *ie; |
| INDEX_ALLOCATION *ia; |
| u8 *index_end, *kaddr; |
| ntfs_attr_search_ctx *actx; |
| struct address_space *ia_mapping; |
| struct page *page; |
| int rc, err = 0; |
| |
| ntfs_debug("Entering."); |
| BUG_ON(!NInoAttr(idx_ni)); |
| BUG_ON(idx_ni->type != AT_INDEX_ALLOCATION); |
| BUG_ON(idx_ni->nr_extents != -1); |
| BUG_ON(!base_ni); |
| BUG_ON(!key); |
| BUG_ON(key_len <= 0); |
| if (!ntfs_is_collation_rule_supported( |
| idx_ni->itype.index.collation_rule)) { |
| ntfs_error(sb, "Index uses unsupported collation rule 0x%x. " |
| "Aborting lookup.", le32_to_cpu( |
| idx_ni->itype.index.collation_rule)); |
| return -EOPNOTSUPP; |
| } |
| /* Get hold of the mft record for the index inode. */ |
| m = map_mft_record(base_ni); |
| if (IS_ERR(m)) { |
| ntfs_error(sb, "map_mft_record() failed with error code %ld.", |
| -PTR_ERR(m)); |
| return PTR_ERR(m); |
| } |
| actx = ntfs_attr_get_search_ctx(base_ni, m); |
| if (unlikely(!actx)) { |
| err = -ENOMEM; |
| goto err_out; |
| } |
| /* Find the index root attribute in the mft record. */ |
| err = ntfs_attr_lookup(AT_INDEX_ROOT, idx_ni->name, idx_ni->name_len, |
| CASE_SENSITIVE, 0, NULL, 0, actx); |
| if (unlikely(err)) { |
| if (err == -ENOENT) { |
| ntfs_error(sb, "Index root attribute missing in inode " |
| "0x%lx.", idx_ni->mft_no); |
| err = -EIO; |
| } |
| goto err_out; |
| } |
| /* Get to the index root value (it has been verified in read_inode). */ |
| ir = (INDEX_ROOT*)((u8*)actx->attr + |
| le16_to_cpu(actx->attr->data.resident.value_offset)); |
| index_end = (u8*)&ir->index + le32_to_cpu(ir->index.index_length); |
| /* The first index entry. */ |
| ie = (INDEX_ENTRY*)((u8*)&ir->index + |
| le32_to_cpu(ir->index.entries_offset)); |
| /* |
| * Loop until we exceed valid memory (corruption case) or until we |
| * reach the last entry. |
| */ |
| for (;; ie = (INDEX_ENTRY*)((u8*)ie + le16_to_cpu(ie->length))) { |
| /* Bounds checks. */ |
| if ((u8*)ie < (u8*)actx->mrec || (u8*)ie + |
| sizeof(INDEX_ENTRY_HEADER) > index_end || |
| (u8*)ie + le16_to_cpu(ie->length) > index_end) |
| goto idx_err_out; |
| /* |
| * The last entry cannot contain a key. It can however contain |
| * a pointer to a child node in the B+tree so we just break out. |
| */ |
| if (ie->flags & INDEX_ENTRY_END) |
| break; |
| /* Further bounds checks. */ |
| if ((u32)sizeof(INDEX_ENTRY_HEADER) + |
| le16_to_cpu(ie->key_length) > |
| le16_to_cpu(ie->data.vi.data_offset) || |
| (u32)le16_to_cpu(ie->data.vi.data_offset) + |
| le16_to_cpu(ie->data.vi.data_length) > |
| le16_to_cpu(ie->length)) |
| goto idx_err_out; |
| /* If the keys match perfectly, we setup @ictx and return 0. */ |
| if ((key_len == le16_to_cpu(ie->key_length)) && !memcmp(key, |
| &ie->key, key_len)) { |
| ir_done: |
| ictx->is_in_root = TRUE; |
| ictx->actx = actx; |
| ictx->base_ni = base_ni; |
| ictx->ia = NULL; |
| ictx->page = NULL; |
| done: |
| ictx->entry = ie; |
| ictx->data = (u8*)ie + |
| le16_to_cpu(ie->data.vi.data_offset); |
| ictx->data_len = le16_to_cpu(ie->data.vi.data_length); |
| ntfs_debug("Done."); |
| return err; |
| } |
| /* |
| * Not a perfect match, need to do full blown collation so we |
| * know which way in the B+tree we have to go. |
| */ |
| rc = ntfs_collate(vol, idx_ni->itype.index.collation_rule, key, |
| key_len, &ie->key, le16_to_cpu(ie->key_length)); |
| /* |
| * If @key collates before the key of the current entry, there |
| * is definitely no such key in this index but we might need to |
| * descend into the B+tree so we just break out of the loop. |
| */ |
| if (rc == -1) |
| break; |
| /* |
| * A match should never happen as the memcmp() call should have |
| * cought it, but we still treat it correctly. |
| */ |
| if (!rc) |
| goto ir_done; |
| /* The keys are not equal, continue the search. */ |
| } |
| /* |
| * We have finished with this index without success. Check for the |
| * presence of a child node and if not present setup @ictx and return |
| * -ENOENT. |
| */ |
| if (!(ie->flags & INDEX_ENTRY_NODE)) { |
| ntfs_debug("Entry not found."); |
| err = -ENOENT; |
| goto ir_done; |
| } /* Child node present, descend into it. */ |
| /* Consistency check: Verify that an index allocation exists. */ |
| if (!NInoIndexAllocPresent(idx_ni)) { |
| ntfs_error(sb, "No index allocation attribute but index entry " |
| "requires one. Inode 0x%lx is corrupt or " |
| "driver bug.", idx_ni->mft_no); |
| goto err_out; |
| } |
| /* Get the starting vcn of the index_block holding the child node. */ |
| vcn = sle64_to_cpup((sle64*)((u8*)ie + le16_to_cpu(ie->length) - 8)); |
| ia_mapping = VFS_I(idx_ni)->i_mapping; |
| /* |
| * We are done with the index root and the mft record. Release them, |
| * otherwise we deadlock with ntfs_map_page(). |
| */ |
| ntfs_attr_put_search_ctx(actx); |
| unmap_mft_record(base_ni); |
| m = NULL; |
| actx = NULL; |
| descend_into_child_node: |
| /* |
| * Convert vcn to index into the index allocation attribute in units |
| * of PAGE_CACHE_SIZE and map the page cache page, reading it from |
| * disk if necessary. |
| */ |
| page = ntfs_map_page(ia_mapping, vcn << |
| idx_ni->itype.index.vcn_size_bits >> PAGE_CACHE_SHIFT); |
| if (IS_ERR(page)) { |
| ntfs_error(sb, "Failed to map index page, error %ld.", |
| -PTR_ERR(page)); |
| err = PTR_ERR(page); |
| goto err_out; |
| } |
| lock_page(page); |
| kaddr = (u8*)page_address(page); |
| fast_descend_into_child_node: |
| /* Get to the index allocation block. */ |
| ia = (INDEX_ALLOCATION*)(kaddr + ((vcn << |
| idx_ni->itype.index.vcn_size_bits) & ~PAGE_CACHE_MASK)); |
| /* Bounds checks. */ |
| if ((u8*)ia < kaddr || (u8*)ia > kaddr + PAGE_CACHE_SIZE) { |
| ntfs_error(sb, "Out of bounds check failed. Corrupt inode " |
| "0x%lx or driver bug.", idx_ni->mft_no); |
| goto unm_err_out; |
| } |
| /* Catch multi sector transfer fixup errors. */ |
| if (unlikely(!ntfs_is_indx_record(ia->magic))) { |
| ntfs_error(sb, "Index record with vcn 0x%llx is corrupt. " |
| "Corrupt inode 0x%lx. Run chkdsk.", |
| (long long)vcn, idx_ni->mft_no); |
| goto unm_err_out; |
| } |
| if (sle64_to_cpu(ia->index_block_vcn) != vcn) { |
| ntfs_error(sb, "Actual VCN (0x%llx) of index buffer is " |
| "different from expected VCN (0x%llx). Inode " |
| "0x%lx is corrupt or driver bug.", |
| (unsigned long long) |
| sle64_to_cpu(ia->index_block_vcn), |
| (unsigned long long)vcn, idx_ni->mft_no); |
| goto unm_err_out; |
| } |
| if (le32_to_cpu(ia->index.allocated_size) + 0x18 != |
| idx_ni->itype.index.block_size) { |
| ntfs_error(sb, "Index buffer (VCN 0x%llx) of inode 0x%lx has " |
| "a size (%u) differing from the index " |
| "specified size (%u). Inode is corrupt or " |
| "driver bug.", (unsigned long long)vcn, |
| idx_ni->mft_no, |
| le32_to_cpu(ia->index.allocated_size) + 0x18, |
| idx_ni->itype.index.block_size); |
| goto unm_err_out; |
| } |
| index_end = (u8*)ia + idx_ni->itype.index.block_size; |
| if (index_end > kaddr + PAGE_CACHE_SIZE) { |
| ntfs_error(sb, "Index buffer (VCN 0x%llx) of inode 0x%lx " |
| "crosses page boundary. Impossible! Cannot " |
| "access! This is probably a bug in the " |
| "driver.", (unsigned long long)vcn, |
| idx_ni->mft_no); |
| goto unm_err_out; |
| } |
| index_end = (u8*)&ia->index + le32_to_cpu(ia->index.index_length); |
| if (index_end > (u8*)ia + idx_ni->itype.index.block_size) { |
| ntfs_error(sb, "Size of index buffer (VCN 0x%llx) of inode " |
| "0x%lx exceeds maximum size.", |
| (unsigned long long)vcn, idx_ni->mft_no); |
| goto unm_err_out; |
| } |
| /* The first index entry. */ |
| ie = (INDEX_ENTRY*)((u8*)&ia->index + |
| le32_to_cpu(ia->index.entries_offset)); |
| /* |
| * Iterate similar to above big loop but applied to index buffer, thus |
| * loop until we exceed valid memory (corruption case) or until we |
| * reach the last entry. |
| */ |
| for (;; ie = (INDEX_ENTRY*)((u8*)ie + le16_to_cpu(ie->length))) { |
| /* Bounds checks. */ |
| if ((u8*)ie < (u8*)ia || (u8*)ie + |
| sizeof(INDEX_ENTRY_HEADER) > index_end || |
| (u8*)ie + le16_to_cpu(ie->length) > index_end) { |
| ntfs_error(sb, "Index entry out of bounds in inode " |
| "0x%lx.", idx_ni->mft_no); |
| goto unm_err_out; |
| } |
| /* |
| * The last entry cannot contain a key. It can however contain |
| * a pointer to a child node in the B+tree so we just break out. |
| */ |
| if (ie->flags & INDEX_ENTRY_END) |
| break; |
| /* Further bounds checks. */ |
| if ((u32)sizeof(INDEX_ENTRY_HEADER) + |
| le16_to_cpu(ie->key_length) > |
| le16_to_cpu(ie->data.vi.data_offset) || |
| (u32)le16_to_cpu(ie->data.vi.data_offset) + |
| le16_to_cpu(ie->data.vi.data_length) > |
| le16_to_cpu(ie->length)) { |
| ntfs_error(sb, "Index entry out of bounds in inode " |
| "0x%lx.", idx_ni->mft_no); |
| goto unm_err_out; |
| } |
| /* If the keys match perfectly, we setup @ictx and return 0. */ |
| if ((key_len == le16_to_cpu(ie->key_length)) && !memcmp(key, |
| &ie->key, key_len)) { |
| ia_done: |
| ictx->is_in_root = FALSE; |
| ictx->actx = NULL; |
| ictx->base_ni = NULL; |
| ictx->ia = ia; |
| ictx->page = page; |
| goto done; |
| } |
| /* |
| * Not a perfect match, need to do full blown collation so we |
| * know which way in the B+tree we have to go. |
| */ |
| rc = ntfs_collate(vol, idx_ni->itype.index.collation_rule, key, |
| key_len, &ie->key, le16_to_cpu(ie->key_length)); |
| /* |
| * If @key collates before the key of the current entry, there |
| * is definitely no such key in this index but we might need to |
| * descend into the B+tree so we just break out of the loop. |
| */ |
| if (rc == -1) |
| break; |
| /* |
| * A match should never happen as the memcmp() call should have |
| * cought it, but we still treat it correctly. |
| */ |
| if (!rc) |
| goto ia_done; |
| /* The keys are not equal, continue the search. */ |
| } |
| /* |
| * We have finished with this index buffer without success. Check for |
| * the presence of a child node and if not present return -ENOENT. |
| */ |
| if (!(ie->flags & INDEX_ENTRY_NODE)) { |
| ntfs_debug("Entry not found."); |
| err = -ENOENT; |
| goto ia_done; |
| } |
| if ((ia->index.flags & NODE_MASK) == LEAF_NODE) { |
| ntfs_error(sb, "Index entry with child node found in a leaf " |
| "node in inode 0x%lx.", idx_ni->mft_no); |
| goto unm_err_out; |
| } |
| /* Child node present, descend into it. */ |
| old_vcn = vcn; |
| vcn = sle64_to_cpup((sle64*)((u8*)ie + le16_to_cpu(ie->length) - 8)); |
| if (vcn >= 0) { |
| /* |
| * If vcn is in the same page cache page as old_vcn we recycle |
| * the mapped page. |
| */ |
| if (old_vcn << vol->cluster_size_bits >> |
| PAGE_CACHE_SHIFT == vcn << |
| vol->cluster_size_bits >> |
| PAGE_CACHE_SHIFT) |
| goto fast_descend_into_child_node; |
| unlock_page(page); |
| ntfs_unmap_page(page); |
| goto descend_into_child_node; |
| } |
| ntfs_error(sb, "Negative child node vcn in inode 0x%lx.", |
| idx_ni->mft_no); |
| unm_err_out: |
| unlock_page(page); |
| ntfs_unmap_page(page); |
| err_out: |
| if (!err) |
| err = -EIO; |
| if (actx) |
| ntfs_attr_put_search_ctx(actx); |
| if (m) |
| unmap_mft_record(base_ni); |
| return err; |
| idx_err_out: |
| ntfs_error(sb, "Corrupt index. Aborting lookup."); |
| goto err_out; |
| } |