1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Copyright (C) 2015 Google, Inc.
4 *
5 * Author: Sami Tolvanen <samitolvanen@google.com>
6 */
7
8 #include "dm-verity-fec.h"
9 #include <linux/math64.h>
10
11 #define DM_MSG_PREFIX "verity-fec"
12
13 /*
14 * If error correction has been configured, returns true.
15 */
verity_fec_is_enabled(struct dm_verity * v)16 bool verity_fec_is_enabled(struct dm_verity *v)
17 {
18 return v->fec && v->fec->dev;
19 }
20
21 /*
22 * Return a pointer to dm_verity_fec_io after dm_verity_io and its variable
23 * length fields.
24 */
fec_io(struct dm_verity_io * io)25 static inline struct dm_verity_fec_io *fec_io(struct dm_verity_io *io)
26 {
27 return (struct dm_verity_fec_io *)
28 ((char *)io + io->v->ti->per_io_data_size - sizeof(struct dm_verity_fec_io));
29 }
30
31 /*
32 * Return an interleaved offset for a byte in RS block.
33 */
fec_interleave(struct dm_verity * v,u64 offset)34 static inline u64 fec_interleave(struct dm_verity *v, u64 offset)
35 {
36 u32 mod;
37
38 mod = do_div(offset, v->fec->rsn);
39 return offset + mod * (v->fec->rounds << v->data_dev_block_bits);
40 }
41
42 /*
43 * Decode an RS block using Reed-Solomon.
44 */
fec_decode_rs8(struct dm_verity * v,struct dm_verity_fec_io * fio,u8 * data,u8 * fec,int neras)45 static int fec_decode_rs8(struct dm_verity *v, struct dm_verity_fec_io *fio,
46 u8 *data, u8 *fec, int neras)
47 {
48 int i;
49 uint16_t par[DM_VERITY_FEC_RSM - DM_VERITY_FEC_MIN_RSN];
50
51 for (i = 0; i < v->fec->roots; i++)
52 par[i] = fec[i];
53
54 return decode_rs8(fio->rs, data, par, v->fec->rsn, NULL, neras,
55 fio->erasures, 0, NULL);
56 }
57
58 /*
59 * Read error-correcting codes for the requested RS block. Returns a pointer
60 * to the data block. Caller is responsible for releasing buf.
61 */
fec_read_parity(struct dm_verity * v,u64 rsb,int index,unsigned int * offset,struct dm_buffer ** buf,unsigned short ioprio)62 static u8 *fec_read_parity(struct dm_verity *v, u64 rsb, int index,
63 unsigned int *offset, struct dm_buffer **buf,
64 unsigned short ioprio)
65 {
66 u64 position, block, rem;
67 u8 *res;
68
69 position = (index + rsb) * v->fec->roots;
70 block = div64_u64_rem(position, v->fec->io_size, &rem);
71 *offset = (unsigned int)rem;
72
73 res = dm_bufio_read_with_ioprio(v->fec->bufio, block, buf, ioprio);
74 if (IS_ERR(res)) {
75 DMERR("%s: FEC %llu: parity read failed (block %llu): %ld",
76 v->data_dev->name, (unsigned long long)rsb,
77 (unsigned long long)block, PTR_ERR(res));
78 *buf = NULL;
79 }
80
81 return res;
82 }
83
84 /* Loop over each preallocated buffer slot. */
85 #define fec_for_each_prealloc_buffer(__i) \
86 for (__i = 0; __i < DM_VERITY_FEC_BUF_PREALLOC; __i++)
87
88 /* Loop over each extra buffer slot. */
89 #define fec_for_each_extra_buffer(io, __i) \
90 for (__i = DM_VERITY_FEC_BUF_PREALLOC; __i < DM_VERITY_FEC_BUF_MAX; __i++)
91
92 /* Loop over each allocated buffer. */
93 #define fec_for_each_buffer(io, __i) \
94 for (__i = 0; __i < (io)->nbufs; __i++)
95
96 /* Loop over each RS block in each allocated buffer. */
97 #define fec_for_each_buffer_rs_block(io, __i, __j) \
98 fec_for_each_buffer(io, __i) \
99 for (__j = 0; __j < 1 << DM_VERITY_FEC_BUF_RS_BITS; __j++)
100
101 /*
102 * Return a pointer to the current RS block when called inside
103 * fec_for_each_buffer_rs_block.
104 */
fec_buffer_rs_block(struct dm_verity * v,struct dm_verity_fec_io * fio,unsigned int i,unsigned int j)105 static inline u8 *fec_buffer_rs_block(struct dm_verity *v,
106 struct dm_verity_fec_io *fio,
107 unsigned int i, unsigned int j)
108 {
109 return &fio->bufs[i][j * v->fec->rsn];
110 }
111
112 /*
113 * Return an index to the current RS block when called inside
114 * fec_for_each_buffer_rs_block.
115 */
fec_buffer_rs_index(unsigned int i,unsigned int j)116 static inline unsigned int fec_buffer_rs_index(unsigned int i, unsigned int j)
117 {
118 return (i << DM_VERITY_FEC_BUF_RS_BITS) + j;
119 }
120
121 /*
122 * Decode all RS blocks from buffers and copy corrected bytes into fio->output
123 * starting from block_offset.
124 */
fec_decode_bufs(struct dm_verity * v,struct dm_verity_io * io,struct dm_verity_fec_io * fio,u64 rsb,int byte_index,unsigned int block_offset,int neras)125 static int fec_decode_bufs(struct dm_verity *v, struct dm_verity_io *io,
126 struct dm_verity_fec_io *fio, u64 rsb, int byte_index,
127 unsigned int block_offset, int neras)
128 {
129 int r, corrected = 0, res;
130 struct dm_buffer *buf;
131 unsigned int n, i, offset;
132 u8 *par, *block;
133 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
134
135 par = fec_read_parity(v, rsb, block_offset, &offset, &buf, bio_prio(bio));
136 if (IS_ERR(par))
137 return PTR_ERR(par);
138
139 /*
140 * Decode the RS blocks we have in bufs. Each RS block results in
141 * one corrected target byte and consumes fec->roots parity bytes.
142 */
143 fec_for_each_buffer_rs_block(fio, n, i) {
144 block = fec_buffer_rs_block(v, fio, n, i);
145 res = fec_decode_rs8(v, fio, block, &par[offset], neras);
146 if (res < 0) {
147 r = res;
148 goto error;
149 }
150
151 corrected += res;
152 fio->output[block_offset] = block[byte_index];
153
154 block_offset++;
155 if (block_offset >= 1 << v->data_dev_block_bits)
156 goto done;
157
158 /* read the next block when we run out of parity bytes */
159 offset += v->fec->roots;
160 if (offset >= v->fec->io_size) {
161 dm_bufio_release(buf);
162
163 par = fec_read_parity(v, rsb, block_offset, &offset, &buf, bio_prio(bio));
164 if (IS_ERR(par))
165 return PTR_ERR(par);
166 }
167 }
168 done:
169 r = corrected;
170 error:
171 dm_bufio_release(buf);
172
173 if (r < 0 && neras)
174 DMERR_LIMIT("%s: FEC %llu: failed to correct: %d",
175 v->data_dev->name, (unsigned long long)rsb, r);
176 else if (r > 0)
177 DMWARN_LIMIT("%s: FEC %llu: corrected %d errors",
178 v->data_dev->name, (unsigned long long)rsb, r);
179
180 return r;
181 }
182
183 /*
184 * Locate data block erasures using verity hashes.
185 */
fec_is_erasure(struct dm_verity * v,struct dm_verity_io * io,u8 * want_digest,u8 * data)186 static int fec_is_erasure(struct dm_verity *v, struct dm_verity_io *io,
187 u8 *want_digest, u8 *data)
188 {
189 if (unlikely(verity_hash(v, io, data, 1 << v->data_dev_block_bits,
190 verity_io_real_digest(v, io), true)))
191 return 0;
192
193 return memcmp(verity_io_real_digest(v, io), want_digest,
194 v->digest_size) != 0;
195 }
196
197 /*
198 * Read data blocks that are part of the RS block and deinterleave as much as
199 * fits into buffers. Check for erasure locations if @neras is non-NULL.
200 */
fec_read_bufs(struct dm_verity * v,struct dm_verity_io * io,u64 rsb,u64 target,unsigned int block_offset,int * neras)201 static int fec_read_bufs(struct dm_verity *v, struct dm_verity_io *io,
202 u64 rsb, u64 target, unsigned int block_offset,
203 int *neras)
204 {
205 bool is_zero;
206 int i, j, target_index = -1;
207 struct dm_buffer *buf;
208 struct dm_bufio_client *bufio;
209 struct dm_verity_fec_io *fio = fec_io(io);
210 u64 block, ileaved;
211 u8 *bbuf, *rs_block;
212 u8 want_digest[HASH_MAX_DIGESTSIZE];
213 unsigned int n, k;
214 struct bio *bio = dm_bio_from_per_bio_data(io, v->ti->per_io_data_size);
215
216 if (neras)
217 *neras = 0;
218
219 if (WARN_ON(v->digest_size > sizeof(want_digest)))
220 return -EINVAL;
221
222 /*
223 * read each of the rsn data blocks that are part of the RS block, and
224 * interleave contents to available bufs
225 */
226 for (i = 0; i < v->fec->rsn; i++) {
227 ileaved = fec_interleave(v, rsb * v->fec->rsn + i);
228
229 /*
230 * target is the data block we want to correct, target_index is
231 * the index of this block within the rsn RS blocks
232 */
233 if (ileaved == target)
234 target_index = i;
235
236 block = ileaved >> v->data_dev_block_bits;
237 bufio = v->fec->data_bufio;
238
239 if (block >= v->data_blocks) {
240 block -= v->data_blocks;
241
242 /*
243 * blocks outside the area were assumed to contain
244 * zeros when encoding data was generated
245 */
246 if (unlikely(block >= v->fec->hash_blocks))
247 continue;
248
249 block += v->hash_start;
250 bufio = v->bufio;
251 }
252
253 bbuf = dm_bufio_read_with_ioprio(bufio, block, &buf, bio_prio(bio));
254 if (IS_ERR(bbuf)) {
255 DMWARN_LIMIT("%s: FEC %llu: read failed (%llu): %ld",
256 v->data_dev->name,
257 (unsigned long long)rsb,
258 (unsigned long long)block, PTR_ERR(bbuf));
259
260 /* assume the block is corrupted */
261 if (neras && *neras <= v->fec->roots)
262 fio->erasures[(*neras)++] = i;
263
264 continue;
265 }
266
267 /* locate erasures if the block is on the data device */
268 if (bufio == v->fec->data_bufio &&
269 verity_hash_for_block(v, io, block, want_digest,
270 &is_zero) == 0) {
271 /* skip known zero blocks entirely */
272 if (is_zero)
273 goto done;
274
275 /*
276 * skip if we have already found the theoretical
277 * maximum number (i.e. fec->roots) of erasures
278 */
279 if (neras && *neras <= v->fec->roots &&
280 fec_is_erasure(v, io, want_digest, bbuf))
281 fio->erasures[(*neras)++] = i;
282 }
283
284 /*
285 * deinterleave and copy the bytes that fit into bufs,
286 * starting from block_offset
287 */
288 fec_for_each_buffer_rs_block(fio, n, j) {
289 k = fec_buffer_rs_index(n, j) + block_offset;
290
291 if (k >= 1 << v->data_dev_block_bits)
292 goto done;
293
294 rs_block = fec_buffer_rs_block(v, fio, n, j);
295 rs_block[i] = bbuf[k];
296 }
297 done:
298 dm_bufio_release(buf);
299 }
300
301 return target_index;
302 }
303
304 /*
305 * Allocate RS control structure and FEC buffers from preallocated mempools,
306 * and attempt to allocate as many extra buffers as available.
307 */
fec_alloc_bufs(struct dm_verity * v,struct dm_verity_fec_io * fio)308 static int fec_alloc_bufs(struct dm_verity *v, struct dm_verity_fec_io *fio)
309 {
310 unsigned int n;
311
312 if (!fio->rs)
313 fio->rs = mempool_alloc(&v->fec->rs_pool, GFP_NOIO);
314
315 fec_for_each_prealloc_buffer(n) {
316 if (fio->bufs[n])
317 continue;
318
319 fio->bufs[n] = mempool_alloc(&v->fec->prealloc_pool, GFP_NOWAIT);
320 if (unlikely(!fio->bufs[n])) {
321 DMERR("failed to allocate FEC buffer");
322 return -ENOMEM;
323 }
324 }
325
326 /* try to allocate the maximum number of buffers */
327 fec_for_each_extra_buffer(fio, n) {
328 if (fio->bufs[n])
329 continue;
330
331 fio->bufs[n] = mempool_alloc(&v->fec->extra_pool, GFP_NOWAIT);
332 /* we can manage with even one buffer if necessary */
333 if (unlikely(!fio->bufs[n]))
334 break;
335 }
336 fio->nbufs = n;
337
338 if (!fio->output)
339 fio->output = mempool_alloc(&v->fec->output_pool, GFP_NOIO);
340
341 return 0;
342 }
343
344 /*
345 * Initialize buffers and clear erasures. fec_read_bufs() assumes buffers are
346 * zeroed before deinterleaving.
347 */
fec_init_bufs(struct dm_verity * v,struct dm_verity_fec_io * fio)348 static void fec_init_bufs(struct dm_verity *v, struct dm_verity_fec_io *fio)
349 {
350 unsigned int n;
351
352 fec_for_each_buffer(fio, n)
353 memset(fio->bufs[n], 0, v->fec->rsn << DM_VERITY_FEC_BUF_RS_BITS);
354
355 memset(fio->erasures, 0, sizeof(fio->erasures));
356 }
357
358 /*
359 * Decode all RS blocks in a single data block and return the target block
360 * (indicated by @offset) in fio->output. If @use_erasures is non-zero, uses
361 * hashes to locate erasures.
362 */
fec_decode_rsb(struct dm_verity * v,struct dm_verity_io * io,struct dm_verity_fec_io * fio,u64 rsb,u64 offset,bool use_erasures)363 static int fec_decode_rsb(struct dm_verity *v, struct dm_verity_io *io,
364 struct dm_verity_fec_io *fio, u64 rsb, u64 offset,
365 bool use_erasures)
366 {
367 int r, neras = 0;
368 unsigned int pos;
369
370 r = fec_alloc_bufs(v, fio);
371 if (unlikely(r < 0))
372 return r;
373
374 for (pos = 0; pos < 1 << v->data_dev_block_bits; ) {
375 fec_init_bufs(v, fio);
376
377 r = fec_read_bufs(v, io, rsb, offset, pos,
378 use_erasures ? &neras : NULL);
379 if (unlikely(r < 0))
380 return r;
381
382 r = fec_decode_bufs(v, io, fio, rsb, r, pos, neras);
383 if (r < 0)
384 return r;
385
386 pos += fio->nbufs << DM_VERITY_FEC_BUF_RS_BITS;
387 }
388
389 /* Always re-validate the corrected block against the expected hash */
390 r = verity_hash(v, io, fio->output, 1 << v->data_dev_block_bits,
391 verity_io_real_digest(v, io), true);
392 if (unlikely(r < 0))
393 return r;
394
395 if (memcmp(verity_io_real_digest(v, io), verity_io_want_digest(v, io),
396 v->digest_size)) {
397 DMERR_LIMIT("%s: FEC %llu: failed to correct (%d erasures)",
398 v->data_dev->name, (unsigned long long)rsb, neras);
399 return -EILSEQ;
400 }
401
402 return 0;
403 }
404
405 /* Correct errors in a block. Copies corrected block to dest. */
verity_fec_decode(struct dm_verity * v,struct dm_verity_io * io,enum verity_block_type type,sector_t block,u8 * dest)406 int verity_fec_decode(struct dm_verity *v, struct dm_verity_io *io,
407 enum verity_block_type type, sector_t block, u8 *dest)
408 {
409 int r;
410 struct dm_verity_fec_io *fio = fec_io(io);
411 u64 offset, res, rsb;
412
413 if (!verity_fec_is_enabled(v))
414 return -EOPNOTSUPP;
415
416 if (fio->level >= DM_VERITY_FEC_MAX_RECURSION) {
417 DMWARN_LIMIT("%s: FEC: recursion too deep", v->data_dev->name);
418 return -EIO;
419 }
420
421 fio->level++;
422
423 if (type == DM_VERITY_BLOCK_TYPE_METADATA)
424 block = block - v->hash_start + v->data_blocks;
425
426 /*
427 * For RS(M, N), the continuous FEC data is divided into blocks of N
428 * bytes. Since block size may not be divisible by N, the last block
429 * is zero padded when decoding.
430 *
431 * Each byte of the block is covered by a different RS(M, N) code,
432 * and each code is interleaved over N blocks to make it less likely
433 * that bursty corruption will leave us in unrecoverable state.
434 */
435
436 offset = block << v->data_dev_block_bits;
437 res = div64_u64(offset, v->fec->rounds << v->data_dev_block_bits);
438
439 /*
440 * The base RS block we can feed to the interleaver to find out all
441 * blocks required for decoding.
442 */
443 rsb = offset - res * (v->fec->rounds << v->data_dev_block_bits);
444
445 /*
446 * Locating erasures is slow, so attempt to recover the block without
447 * them first. Do a second attempt with erasures if the corruption is
448 * bad enough.
449 */
450 r = fec_decode_rsb(v, io, fio, rsb, offset, false);
451 if (r < 0) {
452 r = fec_decode_rsb(v, io, fio, rsb, offset, true);
453 if (r < 0)
454 goto done;
455 }
456
457 memcpy(dest, fio->output, 1 << v->data_dev_block_bits);
458
459 done:
460 fio->level--;
461 return r;
462 }
463
464 /*
465 * Clean up per-bio data.
466 */
verity_fec_finish_io(struct dm_verity_io * io)467 void verity_fec_finish_io(struct dm_verity_io *io)
468 {
469 unsigned int n;
470 struct dm_verity_fec *f = io->v->fec;
471 struct dm_verity_fec_io *fio = fec_io(io);
472
473 if (!verity_fec_is_enabled(io->v))
474 return;
475
476 mempool_free(fio->rs, &f->rs_pool);
477
478 fec_for_each_prealloc_buffer(n)
479 mempool_free(fio->bufs[n], &f->prealloc_pool);
480
481 fec_for_each_extra_buffer(fio, n)
482 mempool_free(fio->bufs[n], &f->extra_pool);
483
484 mempool_free(fio->output, &f->output_pool);
485 }
486
487 /*
488 * Initialize per-bio data.
489 */
verity_fec_init_io(struct dm_verity_io * io)490 void verity_fec_init_io(struct dm_verity_io *io)
491 {
492 struct dm_verity_fec_io *fio = fec_io(io);
493
494 if (!verity_fec_is_enabled(io->v))
495 return;
496
497 fio->rs = NULL;
498 memset(fio->bufs, 0, sizeof(fio->bufs));
499 fio->nbufs = 0;
500 fio->output = NULL;
501 fio->level = 0;
502 }
503
504 /*
505 * Append feature arguments and values to the status table.
506 */
verity_fec_status_table(struct dm_verity * v,unsigned int sz,char * result,unsigned int maxlen)507 unsigned int verity_fec_status_table(struct dm_verity *v, unsigned int sz,
508 char *result, unsigned int maxlen)
509 {
510 if (!verity_fec_is_enabled(v))
511 return sz;
512
513 DMEMIT(" " DM_VERITY_OPT_FEC_DEV " %s "
514 DM_VERITY_OPT_FEC_BLOCKS " %llu "
515 DM_VERITY_OPT_FEC_START " %llu "
516 DM_VERITY_OPT_FEC_ROOTS " %d",
517 v->fec->dev->name,
518 (unsigned long long)v->fec->blocks,
519 (unsigned long long)v->fec->start,
520 v->fec->roots);
521
522 return sz;
523 }
524
verity_fec_dtr(struct dm_verity * v)525 void verity_fec_dtr(struct dm_verity *v)
526 {
527 struct dm_verity_fec *f = v->fec;
528
529 if (!verity_fec_is_enabled(v))
530 goto out;
531
532 mempool_exit(&f->rs_pool);
533 mempool_exit(&f->prealloc_pool);
534 mempool_exit(&f->extra_pool);
535 mempool_exit(&f->output_pool);
536 kmem_cache_destroy(f->cache);
537
538 if (f->data_bufio)
539 dm_bufio_client_destroy(f->data_bufio);
540 if (f->bufio)
541 dm_bufio_client_destroy(f->bufio);
542
543 if (f->dev)
544 dm_put_device(v->ti, f->dev);
545 out:
546 kfree(f);
547 v->fec = NULL;
548 }
549
fec_rs_alloc(gfp_t gfp_mask,void * pool_data)550 static void *fec_rs_alloc(gfp_t gfp_mask, void *pool_data)
551 {
552 struct dm_verity *v = pool_data;
553
554 return init_rs_gfp(8, 0x11d, 0, 1, v->fec->roots, gfp_mask);
555 }
556
fec_rs_free(void * element,void * pool_data)557 static void fec_rs_free(void *element, void *pool_data)
558 {
559 struct rs_control *rs = element;
560
561 if (rs)
562 free_rs(rs);
563 }
564
verity_is_fec_opt_arg(const char * arg_name)565 bool verity_is_fec_opt_arg(const char *arg_name)
566 {
567 return (!strcasecmp(arg_name, DM_VERITY_OPT_FEC_DEV) ||
568 !strcasecmp(arg_name, DM_VERITY_OPT_FEC_BLOCKS) ||
569 !strcasecmp(arg_name, DM_VERITY_OPT_FEC_START) ||
570 !strcasecmp(arg_name, DM_VERITY_OPT_FEC_ROOTS));
571 }
572
verity_fec_parse_opt_args(struct dm_arg_set * as,struct dm_verity * v,unsigned int * argc,const char * arg_name)573 int verity_fec_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v,
574 unsigned int *argc, const char *arg_name)
575 {
576 int r;
577 struct dm_target *ti = v->ti;
578 const char *arg_value;
579 unsigned long long num_ll;
580 unsigned char num_c;
581 char dummy;
582
583 if (!*argc) {
584 ti->error = "FEC feature arguments require a value";
585 return -EINVAL;
586 }
587
588 arg_value = dm_shift_arg(as);
589 (*argc)--;
590
591 if (!strcasecmp(arg_name, DM_VERITY_OPT_FEC_DEV)) {
592 r = dm_get_device(ti, arg_value, BLK_OPEN_READ, &v->fec->dev);
593 if (r) {
594 ti->error = "FEC device lookup failed";
595 return r;
596 }
597
598 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_FEC_BLOCKS)) {
599 if (sscanf(arg_value, "%llu%c", &num_ll, &dummy) != 1 ||
600 ((sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT))
601 >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll)) {
602 ti->error = "Invalid " DM_VERITY_OPT_FEC_BLOCKS;
603 return -EINVAL;
604 }
605 v->fec->blocks = num_ll;
606
607 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_FEC_START)) {
608 if (sscanf(arg_value, "%llu%c", &num_ll, &dummy) != 1 ||
609 ((sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT)) >>
610 (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll)) {
611 ti->error = "Invalid " DM_VERITY_OPT_FEC_START;
612 return -EINVAL;
613 }
614 v->fec->start = num_ll;
615
616 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_FEC_ROOTS)) {
617 if (sscanf(arg_value, "%hhu%c", &num_c, &dummy) != 1 || !num_c ||
618 num_c < (DM_VERITY_FEC_RSM - DM_VERITY_FEC_MAX_RSN) ||
619 num_c > (DM_VERITY_FEC_RSM - DM_VERITY_FEC_MIN_RSN)) {
620 ti->error = "Invalid " DM_VERITY_OPT_FEC_ROOTS;
621 return -EINVAL;
622 }
623 v->fec->roots = num_c;
624
625 } else {
626 ti->error = "Unrecognized verity FEC feature request";
627 return -EINVAL;
628 }
629
630 return 0;
631 }
632
633 /*
634 * Allocate dm_verity_fec for v->fec. Must be called before verity_fec_ctr.
635 */
verity_fec_ctr_alloc(struct dm_verity * v)636 int verity_fec_ctr_alloc(struct dm_verity *v)
637 {
638 struct dm_verity_fec *f;
639
640 f = kzalloc(sizeof(struct dm_verity_fec), GFP_KERNEL);
641 if (!f) {
642 v->ti->error = "Cannot allocate FEC structure";
643 return -ENOMEM;
644 }
645 v->fec = f;
646
647 return 0;
648 }
649
650 /*
651 * Validate arguments and preallocate memory. Must be called after arguments
652 * have been parsed using verity_fec_parse_opt_args.
653 */
verity_fec_ctr(struct dm_verity * v)654 int verity_fec_ctr(struct dm_verity *v)
655 {
656 struct dm_verity_fec *f = v->fec;
657 struct dm_target *ti = v->ti;
658 u64 hash_blocks, fec_blocks;
659 int ret;
660
661 if (!verity_fec_is_enabled(v)) {
662 verity_fec_dtr(v);
663 return 0;
664 }
665
666 /*
667 * FEC is computed over data blocks, possible metadata, and
668 * hash blocks. In other words, FEC covers total of fec_blocks
669 * blocks consisting of the following:
670 *
671 * data blocks | hash blocks | metadata (optional)
672 *
673 * We allow metadata after hash blocks to support a use case
674 * where all data is stored on the same device and FEC covers
675 * the entire area.
676 *
677 * If metadata is included, we require it to be available on the
678 * hash device after the hash blocks.
679 */
680
681 hash_blocks = v->hash_blocks - v->hash_start;
682
683 /*
684 * Require matching block sizes for data and hash devices for
685 * simplicity.
686 */
687 if (v->data_dev_block_bits != v->hash_dev_block_bits) {
688 ti->error = "Block sizes must match to use FEC";
689 return -EINVAL;
690 }
691
692 if (!f->roots) {
693 ti->error = "Missing " DM_VERITY_OPT_FEC_ROOTS;
694 return -EINVAL;
695 }
696 f->rsn = DM_VERITY_FEC_RSM - f->roots;
697
698 if (!f->blocks) {
699 ti->error = "Missing " DM_VERITY_OPT_FEC_BLOCKS;
700 return -EINVAL;
701 }
702
703 f->rounds = f->blocks;
704 if (sector_div(f->rounds, f->rsn))
705 f->rounds++;
706
707 /*
708 * Due to optional metadata, f->blocks can be larger than
709 * data_blocks and hash_blocks combined.
710 */
711 if (f->blocks < v->data_blocks + hash_blocks || !f->rounds) {
712 ti->error = "Invalid " DM_VERITY_OPT_FEC_BLOCKS;
713 return -EINVAL;
714 }
715
716 /*
717 * Metadata is accessed through the hash device, so we require
718 * it to be large enough.
719 */
720 f->hash_blocks = f->blocks - v->data_blocks;
721 if (dm_bufio_get_device_size(v->bufio) < f->hash_blocks) {
722 ti->error = "Hash device is too small for "
723 DM_VERITY_OPT_FEC_BLOCKS;
724 return -E2BIG;
725 }
726
727 if ((f->roots << SECTOR_SHIFT) & ((1 << v->data_dev_block_bits) - 1))
728 f->io_size = 1 << v->data_dev_block_bits;
729 else
730 f->io_size = v->fec->roots << SECTOR_SHIFT;
731
732 f->bufio = dm_bufio_client_create(f->dev->bdev,
733 f->io_size,
734 1, 0, NULL, NULL, 0);
735 if (IS_ERR(f->bufio)) {
736 ti->error = "Cannot initialize FEC bufio client";
737 return PTR_ERR(f->bufio);
738 }
739
740 dm_bufio_set_sector_offset(f->bufio, f->start << (v->data_dev_block_bits - SECTOR_SHIFT));
741
742 fec_blocks = div64_u64(f->rounds * f->roots, v->fec->roots << SECTOR_SHIFT);
743 if (dm_bufio_get_device_size(f->bufio) < fec_blocks) {
744 ti->error = "FEC device is too small";
745 return -E2BIG;
746 }
747
748 f->data_bufio = dm_bufio_client_create(v->data_dev->bdev,
749 1 << v->data_dev_block_bits,
750 1, 0, NULL, NULL, 0);
751 if (IS_ERR(f->data_bufio)) {
752 ti->error = "Cannot initialize FEC data bufio client";
753 return PTR_ERR(f->data_bufio);
754 }
755
756 if (dm_bufio_get_device_size(f->data_bufio) < v->data_blocks) {
757 ti->error = "Data device is too small";
758 return -E2BIG;
759 }
760
761 /* Preallocate an rs_control structure for each worker thread */
762 ret = mempool_init(&f->rs_pool, num_online_cpus(), fec_rs_alloc,
763 fec_rs_free, (void *) v);
764 if (ret) {
765 ti->error = "Cannot allocate RS pool";
766 return ret;
767 }
768
769 f->cache = kmem_cache_create("dm_verity_fec_buffers",
770 f->rsn << DM_VERITY_FEC_BUF_RS_BITS,
771 0, 0, NULL);
772 if (!f->cache) {
773 ti->error = "Cannot create FEC buffer cache";
774 return -ENOMEM;
775 }
776
777 /* Preallocate DM_VERITY_FEC_BUF_PREALLOC buffers for each thread */
778 ret = mempool_init_slab_pool(&f->prealloc_pool, num_online_cpus() *
779 DM_VERITY_FEC_BUF_PREALLOC,
780 f->cache);
781 if (ret) {
782 ti->error = "Cannot allocate FEC buffer prealloc pool";
783 return ret;
784 }
785
786 ret = mempool_init_slab_pool(&f->extra_pool, 0, f->cache);
787 if (ret) {
788 ti->error = "Cannot allocate FEC buffer extra pool";
789 return ret;
790 }
791
792 /* Preallocate an output buffer for each thread */
793 ret = mempool_init_kmalloc_pool(&f->output_pool, num_online_cpus(),
794 1 << v->data_dev_block_bits);
795 if (ret) {
796 ti->error = "Cannot allocate FEC output pool";
797 return ret;
798 }
799
800 /* Reserve space for our per-bio data */
801 ti->per_io_data_size += sizeof(struct dm_verity_fec_io);
802
803 return 0;
804 }
805