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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 | } |
455 |
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