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 }