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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 "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_sem 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, SLAB_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_sem 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_sem 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 | } |