1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3 * Copyright (C) 2017 Oracle. All Rights Reserved.
4 * Author: Darrick J. Wong <darrick.wong@oracle.com>
5 */
6 #include "xfs.h"
7 #include "xfs_fs.h"
8 #include "xfs_shared.h"
9 #include "xfs_format.h"
10 #include "xfs_trans_resv.h"
11 #include "xfs_mount.h"
12 #include "xfs_log_format.h"
13 #include "xfs_inode.h"
14 #include "xfs_da_format.h"
15 #include "xfs_da_btree.h"
16 #include "xfs_attr.h"
17 #include "xfs_attr_leaf.h"
18 #include "scrub/scrub.h"
19 #include "scrub/common.h"
20 #include "scrub/dabtree.h"
21 #include "scrub/attr.h"
22
23 /*
24 * Allocate enough memory to hold an attr value and attr block bitmaps,
25 * reallocating the buffer if necessary. Buffer contents are not preserved
26 * across a reallocation.
27 */
28 static int
xchk_setup_xattr_buf(struct xfs_scrub * sc,size_t value_size,gfp_t flags)29 xchk_setup_xattr_buf(
30 struct xfs_scrub *sc,
31 size_t value_size,
32 gfp_t flags)
33 {
34 size_t sz;
35 struct xchk_xattr_buf *ab = sc->buf;
36
37 /*
38 * We need enough space to read an xattr value from the file or enough
39 * space to hold three copies of the xattr free space bitmap. We don't
40 * need the buffer space for both purposes at the same time.
41 */
42 sz = 3 * sizeof(long) * BITS_TO_LONGS(sc->mp->m_attr_geo->blksize);
43 sz = max_t(size_t, sz, value_size);
44
45 /*
46 * If there's already a buffer, figure out if we need to reallocate it
47 * to accommodate a larger size.
48 */
49 if (ab) {
50 if (sz <= ab->sz)
51 return 0;
52 kmem_free(ab);
53 sc->buf = NULL;
54 }
55
56 /*
57 * Don't zero the buffer upon allocation to avoid runtime overhead.
58 * All users must be careful never to read uninitialized contents.
59 */
60 ab = kvmalloc(sizeof(*ab) + sz, flags);
61 if (!ab)
62 return -ENOMEM;
63
64 ab->sz = sz;
65 sc->buf = ab;
66 return 0;
67 }
68
69 /* Set us up to scrub an inode's extended attributes. */
70 int
xchk_setup_xattr(struct xfs_scrub * sc)71 xchk_setup_xattr(
72 struct xfs_scrub *sc)
73 {
74 int error;
75
76 /*
77 * We failed to get memory while checking attrs, so this time try to
78 * get all the memory we're ever going to need. Allocate the buffer
79 * without the inode lock held, which means we can sleep.
80 */
81 if (sc->flags & XCHK_TRY_HARDER) {
82 error = xchk_setup_xattr_buf(sc, XATTR_SIZE_MAX, GFP_KERNEL);
83 if (error)
84 return error;
85 }
86
87 return xchk_setup_inode_contents(sc, 0);
88 }
89
90 /* Extended Attributes */
91
92 struct xchk_xattr {
93 struct xfs_attr_list_context context;
94 struct xfs_scrub *sc;
95 };
96
97 /*
98 * Check that an extended attribute key can be looked up by hash.
99 *
100 * We use the XFS attribute list iterator (i.e. xfs_attr_list_ilocked)
101 * to call this function for every attribute key in an inode. Once
102 * we're here, we load the attribute value to see if any errors happen,
103 * or if we get more or less data than we expected.
104 */
105 static void
xchk_xattr_listent(struct xfs_attr_list_context * context,int flags,unsigned char * name,int namelen,int valuelen)106 xchk_xattr_listent(
107 struct xfs_attr_list_context *context,
108 int flags,
109 unsigned char *name,
110 int namelen,
111 int valuelen)
112 {
113 struct xchk_xattr *sx;
114 struct xfs_da_args args = { NULL };
115 int error = 0;
116
117 sx = container_of(context, struct xchk_xattr, context);
118
119 if (xchk_should_terminate(sx->sc, &error)) {
120 context->seen_enough = error;
121 return;
122 }
123
124 if (flags & XFS_ATTR_INCOMPLETE) {
125 /* Incomplete attr key, just mark the inode for preening. */
126 xchk_ino_set_preen(sx->sc, context->dp->i_ino);
127 return;
128 }
129
130 /* Does this name make sense? */
131 if (!xfs_attr_namecheck(name, namelen)) {
132 xchk_fblock_set_corrupt(sx->sc, XFS_ATTR_FORK, args.blkno);
133 return;
134 }
135
136 /*
137 * Try to allocate enough memory to extrat the attr value. If that
138 * doesn't work, we overload the seen_enough variable to convey
139 * the error message back to the main scrub function.
140 */
141 error = xchk_setup_xattr_buf(sx->sc, valuelen,
142 GFP_KERNEL | __GFP_RETRY_MAYFAIL);
143 if (error == -ENOMEM)
144 error = -EDEADLOCK;
145 if (error) {
146 context->seen_enough = error;
147 return;
148 }
149
150 args.op_flags = XFS_DA_OP_NOTIME;
151 args.attr_filter = flags & XFS_ATTR_NSP_ONDISK_MASK;
152 args.geo = context->dp->i_mount->m_attr_geo;
153 args.whichfork = XFS_ATTR_FORK;
154 args.dp = context->dp;
155 args.name = name;
156 args.namelen = namelen;
157 args.hashval = xfs_da_hashname(args.name, args.namelen);
158 args.trans = context->tp;
159 args.value = xchk_xattr_valuebuf(sx->sc);
160 args.valuelen = valuelen;
161
162 error = xfs_attr_get_ilocked(&args);
163 /* ENODATA means the hash lookup failed and the attr is bad */
164 if (error == -ENODATA)
165 error = -EFSCORRUPTED;
166 if (!xchk_fblock_process_error(sx->sc, XFS_ATTR_FORK, args.blkno,
167 &error))
168 goto fail_xref;
169 if (args.valuelen != valuelen)
170 xchk_fblock_set_corrupt(sx->sc, XFS_ATTR_FORK,
171 args.blkno);
172 fail_xref:
173 if (sx->sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
174 context->seen_enough = 1;
175 return;
176 }
177
178 /*
179 * Mark a range [start, start+len) in this map. Returns true if the
180 * region was free, and false if there's a conflict or a problem.
181 *
182 * Within a char, the lowest bit of the char represents the byte with
183 * the smallest address
184 */
185 STATIC bool
xchk_xattr_set_map(struct xfs_scrub * sc,unsigned long * map,unsigned int start,unsigned int len)186 xchk_xattr_set_map(
187 struct xfs_scrub *sc,
188 unsigned long *map,
189 unsigned int start,
190 unsigned int len)
191 {
192 unsigned int mapsize = sc->mp->m_attr_geo->blksize;
193 bool ret = true;
194
195 if (start >= mapsize)
196 return false;
197 if (start + len > mapsize) {
198 len = mapsize - start;
199 ret = false;
200 }
201
202 if (find_next_bit(map, mapsize, start) < start + len)
203 ret = false;
204 bitmap_set(map, start, len);
205
206 return ret;
207 }
208
209 /*
210 * Check the leaf freemap from the usage bitmap. Returns false if the
211 * attr freemap has problems or points to used space.
212 */
213 STATIC bool
xchk_xattr_check_freemap(struct xfs_scrub * sc,unsigned long * map,struct xfs_attr3_icleaf_hdr * leafhdr)214 xchk_xattr_check_freemap(
215 struct xfs_scrub *sc,
216 unsigned long *map,
217 struct xfs_attr3_icleaf_hdr *leafhdr)
218 {
219 unsigned long *freemap = xchk_xattr_freemap(sc);
220 unsigned long *dstmap = xchk_xattr_dstmap(sc);
221 unsigned int mapsize = sc->mp->m_attr_geo->blksize;
222 int i;
223
224 /* Construct bitmap of freemap contents. */
225 bitmap_zero(freemap, mapsize);
226 for (i = 0; i < XFS_ATTR_LEAF_MAPSIZE; i++) {
227 if (!xchk_xattr_set_map(sc, freemap,
228 leafhdr->freemap[i].base,
229 leafhdr->freemap[i].size))
230 return false;
231 }
232
233 /* Look for bits that are set in freemap and are marked in use. */
234 return bitmap_and(dstmap, freemap, map, mapsize) == 0;
235 }
236
237 /*
238 * Check this leaf entry's relations to everything else.
239 * Returns the number of bytes used for the name/value data.
240 */
241 STATIC void
xchk_xattr_entry(struct xchk_da_btree * ds,int level,char * buf_end,struct xfs_attr_leafblock * leaf,struct xfs_attr3_icleaf_hdr * leafhdr,struct xfs_attr_leaf_entry * ent,int idx,unsigned int * usedbytes,__u32 * last_hashval)242 xchk_xattr_entry(
243 struct xchk_da_btree *ds,
244 int level,
245 char *buf_end,
246 struct xfs_attr_leafblock *leaf,
247 struct xfs_attr3_icleaf_hdr *leafhdr,
248 struct xfs_attr_leaf_entry *ent,
249 int idx,
250 unsigned int *usedbytes,
251 __u32 *last_hashval)
252 {
253 struct xfs_mount *mp = ds->state->mp;
254 unsigned long *usedmap = xchk_xattr_usedmap(ds->sc);
255 char *name_end;
256 struct xfs_attr_leaf_name_local *lentry;
257 struct xfs_attr_leaf_name_remote *rentry;
258 unsigned int nameidx;
259 unsigned int namesize;
260
261 if (ent->pad2 != 0)
262 xchk_da_set_corrupt(ds, level);
263
264 /* Hash values in order? */
265 if (be32_to_cpu(ent->hashval) < *last_hashval)
266 xchk_da_set_corrupt(ds, level);
267 *last_hashval = be32_to_cpu(ent->hashval);
268
269 nameidx = be16_to_cpu(ent->nameidx);
270 if (nameidx < leafhdr->firstused ||
271 nameidx >= mp->m_attr_geo->blksize) {
272 xchk_da_set_corrupt(ds, level);
273 return;
274 }
275
276 /* Check the name information. */
277 if (ent->flags & XFS_ATTR_LOCAL) {
278 lentry = xfs_attr3_leaf_name_local(leaf, idx);
279 namesize = xfs_attr_leaf_entsize_local(lentry->namelen,
280 be16_to_cpu(lentry->valuelen));
281 name_end = (char *)lentry + namesize;
282 if (lentry->namelen == 0)
283 xchk_da_set_corrupt(ds, level);
284 } else {
285 rentry = xfs_attr3_leaf_name_remote(leaf, idx);
286 namesize = xfs_attr_leaf_entsize_remote(rentry->namelen);
287 name_end = (char *)rentry + namesize;
288 if (rentry->namelen == 0 || rentry->valueblk == 0)
289 xchk_da_set_corrupt(ds, level);
290 }
291 if (name_end > buf_end)
292 xchk_da_set_corrupt(ds, level);
293
294 if (!xchk_xattr_set_map(ds->sc, usedmap, nameidx, namesize))
295 xchk_da_set_corrupt(ds, level);
296 if (!(ds->sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT))
297 *usedbytes += namesize;
298 }
299
300 /* Scrub an attribute leaf. */
301 STATIC int
xchk_xattr_block(struct xchk_da_btree * ds,int level)302 xchk_xattr_block(
303 struct xchk_da_btree *ds,
304 int level)
305 {
306 struct xfs_attr3_icleaf_hdr leafhdr;
307 struct xfs_mount *mp = ds->state->mp;
308 struct xfs_da_state_blk *blk = &ds->state->path.blk[level];
309 struct xfs_buf *bp = blk->bp;
310 xfs_dablk_t *last_checked = ds->private;
311 struct xfs_attr_leafblock *leaf = bp->b_addr;
312 struct xfs_attr_leaf_entry *ent;
313 struct xfs_attr_leaf_entry *entries;
314 unsigned long *usedmap;
315 char *buf_end;
316 size_t off;
317 __u32 last_hashval = 0;
318 unsigned int usedbytes = 0;
319 unsigned int hdrsize;
320 int i;
321 int error;
322
323 if (*last_checked == blk->blkno)
324 return 0;
325
326 /* Allocate memory for block usage checking. */
327 error = xchk_setup_xattr_buf(ds->sc, 0,
328 GFP_KERNEL | __GFP_RETRY_MAYFAIL);
329 if (error == -ENOMEM)
330 return -EDEADLOCK;
331 if (error)
332 return error;
333 usedmap = xchk_xattr_usedmap(ds->sc);
334
335 *last_checked = blk->blkno;
336 bitmap_zero(usedmap, mp->m_attr_geo->blksize);
337
338 /* Check all the padding. */
339 if (xfs_has_crc(ds->sc->mp)) {
340 struct xfs_attr3_leafblock *leaf = bp->b_addr;
341
342 if (leaf->hdr.pad1 != 0 || leaf->hdr.pad2 != 0 ||
343 leaf->hdr.info.hdr.pad != 0)
344 xchk_da_set_corrupt(ds, level);
345 } else {
346 if (leaf->hdr.pad1 != 0 || leaf->hdr.info.pad != 0)
347 xchk_da_set_corrupt(ds, level);
348 }
349
350 /* Check the leaf header */
351 xfs_attr3_leaf_hdr_from_disk(mp->m_attr_geo, &leafhdr, leaf);
352 hdrsize = xfs_attr3_leaf_hdr_size(leaf);
353
354 if (leafhdr.usedbytes > mp->m_attr_geo->blksize)
355 xchk_da_set_corrupt(ds, level);
356 if (leafhdr.firstused > mp->m_attr_geo->blksize)
357 xchk_da_set_corrupt(ds, level);
358 if (leafhdr.firstused < hdrsize)
359 xchk_da_set_corrupt(ds, level);
360 if (!xchk_xattr_set_map(ds->sc, usedmap, 0, hdrsize))
361 xchk_da_set_corrupt(ds, level);
362
363 if (ds->sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
364 goto out;
365
366 entries = xfs_attr3_leaf_entryp(leaf);
367 if ((char *)&entries[leafhdr.count] > (char *)leaf + leafhdr.firstused)
368 xchk_da_set_corrupt(ds, level);
369
370 buf_end = (char *)bp->b_addr + mp->m_attr_geo->blksize;
371 for (i = 0, ent = entries; i < leafhdr.count; ent++, i++) {
372 /* Mark the leaf entry itself. */
373 off = (char *)ent - (char *)leaf;
374 if (!xchk_xattr_set_map(ds->sc, usedmap, off,
375 sizeof(xfs_attr_leaf_entry_t))) {
376 xchk_da_set_corrupt(ds, level);
377 goto out;
378 }
379
380 /* Check the entry and nameval. */
381 xchk_xattr_entry(ds, level, buf_end, leaf, &leafhdr,
382 ent, i, &usedbytes, &last_hashval);
383
384 if (ds->sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
385 goto out;
386 }
387
388 if (!xchk_xattr_check_freemap(ds->sc, usedmap, &leafhdr))
389 xchk_da_set_corrupt(ds, level);
390
391 if (leafhdr.usedbytes != usedbytes)
392 xchk_da_set_corrupt(ds, level);
393
394 out:
395 return 0;
396 }
397
398 /* Scrub a attribute btree record. */
399 STATIC int
xchk_xattr_rec(struct xchk_da_btree * ds,int level)400 xchk_xattr_rec(
401 struct xchk_da_btree *ds,
402 int level)
403 {
404 struct xfs_mount *mp = ds->state->mp;
405 struct xfs_da_state_blk *blk = &ds->state->path.blk[level];
406 struct xfs_attr_leaf_name_local *lentry;
407 struct xfs_attr_leaf_name_remote *rentry;
408 struct xfs_buf *bp;
409 struct xfs_attr_leaf_entry *ent;
410 xfs_dahash_t calc_hash;
411 xfs_dahash_t hash;
412 int nameidx;
413 int hdrsize;
414 unsigned int badflags;
415 int error;
416
417 ASSERT(blk->magic == XFS_ATTR_LEAF_MAGIC);
418
419 ent = xfs_attr3_leaf_entryp(blk->bp->b_addr) + blk->index;
420
421 /* Check the whole block, if necessary. */
422 error = xchk_xattr_block(ds, level);
423 if (error)
424 goto out;
425 if (ds->sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
426 goto out;
427
428 /* Check the hash of the entry. */
429 error = xchk_da_btree_hash(ds, level, &ent->hashval);
430 if (error)
431 goto out;
432
433 /* Find the attr entry's location. */
434 bp = blk->bp;
435 hdrsize = xfs_attr3_leaf_hdr_size(bp->b_addr);
436 nameidx = be16_to_cpu(ent->nameidx);
437 if (nameidx < hdrsize || nameidx >= mp->m_attr_geo->blksize) {
438 xchk_da_set_corrupt(ds, level);
439 goto out;
440 }
441
442 /* Retrieve the entry and check it. */
443 hash = be32_to_cpu(ent->hashval);
444 badflags = ~(XFS_ATTR_LOCAL | XFS_ATTR_ROOT | XFS_ATTR_SECURE |
445 XFS_ATTR_INCOMPLETE);
446 if ((ent->flags & badflags) != 0)
447 xchk_da_set_corrupt(ds, level);
448 if (ent->flags & XFS_ATTR_LOCAL) {
449 lentry = (struct xfs_attr_leaf_name_local *)
450 (((char *)bp->b_addr) + nameidx);
451 if (lentry->namelen <= 0) {
452 xchk_da_set_corrupt(ds, level);
453 goto out;
454 }
455 calc_hash = xfs_da_hashname(lentry->nameval, lentry->namelen);
456 } else {
457 rentry = (struct xfs_attr_leaf_name_remote *)
458 (((char *)bp->b_addr) + nameidx);
459 if (rentry->namelen <= 0) {
460 xchk_da_set_corrupt(ds, level);
461 goto out;
462 }
463 calc_hash = xfs_da_hashname(rentry->name, rentry->namelen);
464 }
465 if (calc_hash != hash)
466 xchk_da_set_corrupt(ds, level);
467
468 out:
469 return error;
470 }
471
472 /* Scrub the extended attribute metadata. */
473 int
xchk_xattr(struct xfs_scrub * sc)474 xchk_xattr(
475 struct xfs_scrub *sc)
476 {
477 struct xchk_xattr sx;
478 xfs_dablk_t last_checked = -1U;
479 int error = 0;
480
481 if (!xfs_inode_hasattr(sc->ip))
482 return -ENOENT;
483
484 memset(&sx, 0, sizeof(sx));
485 /* Check attribute tree structure */
486 error = xchk_da_btree(sc, XFS_ATTR_FORK, xchk_xattr_rec,
487 &last_checked);
488 if (error)
489 goto out;
490
491 if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
492 goto out;
493
494 /* Check that every attr key can also be looked up by hash. */
495 sx.context.dp = sc->ip;
496 sx.context.resynch = 1;
497 sx.context.put_listent = xchk_xattr_listent;
498 sx.context.tp = sc->tp;
499 sx.context.allow_incomplete = true;
500 sx.sc = sc;
501
502 /*
503 * Look up every xattr in this file by name.
504 *
505 * Use the backend implementation of xfs_attr_list to call
506 * xchk_xattr_listent on every attribute key in this inode.
507 * In other words, we use the same iterator/callback mechanism
508 * that listattr uses to scrub extended attributes, though in our
509 * _listent function, we check the value of the attribute.
510 *
511 * The VFS only locks i_rwsem when modifying attrs, so keep all
512 * three locks held because that's the only way to ensure we're
513 * the only thread poking into the da btree. We traverse the da
514 * btree while holding a leaf buffer locked for the xattr name
515 * iteration, which doesn't really follow the usual buffer
516 * locking order.
517 */
518 error = xfs_attr_list_ilocked(&sx.context);
519 if (!xchk_fblock_process_error(sc, XFS_ATTR_FORK, 0, &error))
520 goto out;
521
522 /* Did our listent function try to return any errors? */
523 if (sx.context.seen_enough < 0)
524 error = sx.context.seen_enough;
525 out:
526 return error;
527 }
528