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 *) verity_io_digest_end(io->v, io);
28 }
29
30 /*
31 * Return an interleaved offset for a byte in RS block.
32 */
fec_interleave(struct dm_verity * v,u64 offset)33 static inline u64 fec_interleave(struct dm_verity *v, u64 offset)
34 {
35 u32 mod;
36
37 mod = do_div(offset, v->fec->rsn);
38 return offset + mod * (v->fec->rounds << v->data_dev_block_bits);
39 }
40
41 /*
42 * Decode an RS block using Reed-Solomon.
43 */
fec_decode_rs8(struct dm_verity * v,struct dm_verity_fec_io * fio,u8 * data,u8 * fec,int neras)44 static int fec_decode_rs8(struct dm_verity *v, struct dm_verity_fec_io *fio,
45 u8 *data, u8 *fec, int neras)
46 {
47 int i;
48 uint16_t par[DM_VERITY_FEC_RSM - DM_VERITY_FEC_MIN_RSN];
49
50 for (i = 0; i < v->fec->roots; i++)
51 par[i] = fec[i];
52
53 return decode_rs8(fio->rs, data, par, v->fec->rsn, NULL, neras,
54 fio->erasures, 0, NULL);
55 }
56
57 /*
58 * Read error-correcting codes for the requested RS block. Returns a pointer
59 * to the data block. Caller is responsible for releasing buf.
60 */
fec_read_parity(struct dm_verity * v,u64 rsb,int index,unsigned * offset,struct dm_buffer ** buf)61 static u8 *fec_read_parity(struct dm_verity *v, u64 rsb, int index,
62 unsigned *offset, struct dm_buffer **buf)
63 {
64 u64 position, block;
65 u8 *res;
66
67 position = (index + rsb) * v->fec->roots;
68 block = position >> v->data_dev_block_bits;
69 *offset = (unsigned)(position - (block << v->data_dev_block_bits));
70
71 res = dm_bufio_read(v->fec->bufio, v->fec->start + block, buf);
72 if (IS_ERR(res)) {
73 DMERR("%s: FEC %llu: parity read failed (block %llu): %ld",
74 v->data_dev->name, (unsigned long long)rsb,
75 (unsigned long long)(v->fec->start + block),
76 PTR_ERR(res));
77 *buf = NULL;
78 }
79
80 return res;
81 }
82
83 /* Loop over each preallocated buffer slot. */
84 #define fec_for_each_prealloc_buffer(__i) \
85 for (__i = 0; __i < DM_VERITY_FEC_BUF_PREALLOC; __i++)
86
87 /* Loop over each extra buffer slot. */
88 #define fec_for_each_extra_buffer(io, __i) \
89 for (__i = DM_VERITY_FEC_BUF_PREALLOC; __i < DM_VERITY_FEC_BUF_MAX; __i++)
90
91 /* Loop over each allocated buffer. */
92 #define fec_for_each_buffer(io, __i) \
93 for (__i = 0; __i < (io)->nbufs; __i++)
94
95 /* Loop over each RS block in each allocated buffer. */
96 #define fec_for_each_buffer_rs_block(io, __i, __j) \
97 fec_for_each_buffer(io, __i) \
98 for (__j = 0; __j < 1 << DM_VERITY_FEC_BUF_RS_BITS; __j++)
99
100 /*
101 * Return a pointer to the current RS block when called inside
102 * fec_for_each_buffer_rs_block.
103 */
fec_buffer_rs_block(struct dm_verity * v,struct dm_verity_fec_io * fio,unsigned i,unsigned j)104 static inline u8 *fec_buffer_rs_block(struct dm_verity *v,
105 struct dm_verity_fec_io *fio,
106 unsigned i, unsigned j)
107 {
108 return &fio->bufs[i][j * v->fec->rsn];
109 }
110
111 /*
112 * Return an index to the current RS block when called inside
113 * fec_for_each_buffer_rs_block.
114 */
fec_buffer_rs_index(unsigned i,unsigned j)115 static inline unsigned fec_buffer_rs_index(unsigned i, unsigned j)
116 {
117 return (i << DM_VERITY_FEC_BUF_RS_BITS) + j;
118 }
119
120 /*
121 * Decode all RS blocks from buffers and copy corrected bytes into fio->output
122 * starting from block_offset.
123 */
fec_decode_bufs(struct dm_verity * v,struct dm_verity_fec_io * fio,u64 rsb,int byte_index,unsigned block_offset,int neras)124 static int fec_decode_bufs(struct dm_verity *v, struct dm_verity_fec_io *fio,
125 u64 rsb, int byte_index, unsigned block_offset,
126 int neras)
127 {
128 int r, corrected = 0, res;
129 struct dm_buffer *buf;
130 unsigned n, i, offset;
131 u8 *par, *block;
132
133 par = fec_read_parity(v, rsb, block_offset, &offset, &buf);
134 if (IS_ERR(par))
135 return PTR_ERR(par);
136
137 /*
138 * Decode the RS blocks we have in bufs. Each RS block results in
139 * one corrected target byte and consumes fec->roots parity bytes.
140 */
141 fec_for_each_buffer_rs_block(fio, n, i) {
142 block = fec_buffer_rs_block(v, fio, n, i);
143 res = fec_decode_rs8(v, fio, block, &par[offset], neras);
144 if (res < 0) {
145 r = res;
146 goto error;
147 }
148
149 corrected += res;
150 fio->output[block_offset] = block[byte_index];
151
152 block_offset++;
153 if (block_offset >= 1 << v->data_dev_block_bits)
154 goto done;
155
156 /* read the next block when we run out of parity bytes */
157 offset += v->fec->roots;
158 if (offset >= 1 << v->data_dev_block_bits) {
159 dm_bufio_release(buf);
160
161 par = fec_read_parity(v, rsb, block_offset, &offset, &buf);
162 if (IS_ERR(par))
163 return PTR_ERR(par);
164 }
165 }
166 done:
167 r = corrected;
168 error:
169 dm_bufio_release(buf);
170
171 if (r < 0 && neras)
172 DMERR_LIMIT("%s: FEC %llu: failed to correct: %d",
173 v->data_dev->name, (unsigned long long)rsb, r);
174 else if (r > 0)
175 DMWARN_LIMIT("%s: FEC %llu: corrected %d errors",
176 v->data_dev->name, (unsigned long long)rsb, r);
177
178 return r;
179 }
180
181 /*
182 * Locate data block erasures using verity hashes.
183 */
fec_is_erasure(struct dm_verity * v,struct dm_verity_io * io,u8 * want_digest,u8 * data)184 static int fec_is_erasure(struct dm_verity *v, struct dm_verity_io *io,
185 u8 *want_digest, u8 *data)
186 {
187 if (unlikely(verity_hash(v, verity_io_hash_req(v, io),
188 data, 1 << v->data_dev_block_bits,
189 verity_io_real_digest(v, io))))
190 return 0;
191
192 return memcmp(verity_io_real_digest(v, io), want_digest,
193 v->digest_size) != 0;
194 }
195
196 /*
197 * Read data blocks that are part of the RS block and deinterleave as much as
198 * fits into buffers. Check for erasure locations if @neras is non-NULL.
199 */
fec_read_bufs(struct dm_verity * v,struct dm_verity_io * io,u64 rsb,u64 target,unsigned block_offset,int * neras)200 static int fec_read_bufs(struct dm_verity *v, struct dm_verity_io *io,
201 u64 rsb, u64 target, unsigned block_offset,
202 int *neras)
203 {
204 bool is_zero;
205 int i, j, target_index = -1;
206 struct dm_buffer *buf;
207 struct dm_bufio_client *bufio;
208 struct dm_verity_fec_io *fio = fec_io(io);
209 u64 block, ileaved;
210 u8 *bbuf, *rs_block;
211 u8 want_digest[HASH_MAX_DIGESTSIZE];
212 unsigned n, k;
213
214 if (neras)
215 *neras = 0;
216
217 if (WARN_ON(v->digest_size > sizeof(want_digest)))
218 return -EINVAL;
219
220 /*
221 * read each of the rsn data blocks that are part of the RS block, and
222 * interleave contents to available bufs
223 */
224 for (i = 0; i < v->fec->rsn; i++) {
225 ileaved = fec_interleave(v, rsb * v->fec->rsn + i);
226
227 /*
228 * target is the data block we want to correct, target_index is
229 * the index of this block within the rsn RS blocks
230 */
231 if (ileaved == target)
232 target_index = i;
233
234 block = ileaved >> v->data_dev_block_bits;
235 bufio = v->fec->data_bufio;
236
237 if (block >= v->data_blocks) {
238 block -= v->data_blocks;
239
240 /*
241 * blocks outside the area were assumed to contain
242 * zeros when encoding data was generated
243 */
244 if (unlikely(block >= v->fec->hash_blocks))
245 continue;
246
247 block += v->hash_start;
248 bufio = v->bufio;
249 }
250
251 bbuf = dm_bufio_read(bufio, block, &buf);
252 if (IS_ERR(bbuf)) {
253 DMWARN_LIMIT("%s: FEC %llu: read failed (%llu): %ld",
254 v->data_dev->name,
255 (unsigned long long)rsb,
256 (unsigned long long)block, PTR_ERR(bbuf));
257
258 /* assume the block is corrupted */
259 if (neras && *neras <= v->fec->roots)
260 fio->erasures[(*neras)++] = i;
261
262 continue;
263 }
264
265 /* locate erasures if the block is on the data device */
266 if (bufio == v->fec->data_bufio &&
267 verity_hash_for_block(v, io, block, want_digest,
268 &is_zero) == 0) {
269 /* skip known zero blocks entirely */
270 if (is_zero)
271 goto done;
272
273 /*
274 * skip if we have already found the theoretical
275 * maximum number (i.e. fec->roots) of erasures
276 */
277 if (neras && *neras <= v->fec->roots &&
278 fec_is_erasure(v, io, want_digest, bbuf))
279 fio->erasures[(*neras)++] = i;
280 }
281
282 /*
283 * deinterleave and copy the bytes that fit into bufs,
284 * starting from block_offset
285 */
286 fec_for_each_buffer_rs_block(fio, n, j) {
287 k = fec_buffer_rs_index(n, j) + block_offset;
288
289 if (k >= 1 << v->data_dev_block_bits)
290 goto done;
291
292 rs_block = fec_buffer_rs_block(v, fio, n, j);
293 rs_block[i] = bbuf[k];
294 }
295 done:
296 dm_bufio_release(buf);
297 }
298
299 return target_index;
300 }
301
302 /*
303 * Allocate RS control structure and FEC buffers from preallocated mempools,
304 * and attempt to allocate as many extra buffers as available.
305 */
fec_alloc_bufs(struct dm_verity * v,struct dm_verity_fec_io * fio)306 static int fec_alloc_bufs(struct dm_verity *v, struct dm_verity_fec_io *fio)
307 {
308 unsigned n;
309
310 if (!fio->rs)
311 fio->rs = mempool_alloc(&v->fec->rs_pool, GFP_NOIO);
312
313 fec_for_each_prealloc_buffer(n) {
314 if (fio->bufs[n])
315 continue;
316
317 fio->bufs[n] = mempool_alloc(&v->fec->prealloc_pool, GFP_NOWAIT);
318 if (unlikely(!fio->bufs[n])) {
319 DMERR("failed to allocate FEC buffer");
320 return -ENOMEM;
321 }
322 }
323
324 /* try to allocate the maximum number of buffers */
325 fec_for_each_extra_buffer(fio, n) {
326 if (fio->bufs[n])
327 continue;
328
329 fio->bufs[n] = mempool_alloc(&v->fec->extra_pool, GFP_NOWAIT);
330 /* we can manage with even one buffer if necessary */
331 if (unlikely(!fio->bufs[n]))
332 break;
333 }
334 fio->nbufs = n;
335
336 if (!fio->output)
337 fio->output = mempool_alloc(&v->fec->output_pool, GFP_NOIO);
338
339 return 0;
340 }
341
342 /*
343 * Initialize buffers and clear erasures. fec_read_bufs() assumes buffers are
344 * zeroed before deinterleaving.
345 */
fec_init_bufs(struct dm_verity * v,struct dm_verity_fec_io * fio)346 static void fec_init_bufs(struct dm_verity *v, struct dm_verity_fec_io *fio)
347 {
348 unsigned n;
349
350 fec_for_each_buffer(fio, n)
351 memset(fio->bufs[n], 0, v->fec->rsn << DM_VERITY_FEC_BUF_RS_BITS);
352
353 memset(fio->erasures, 0, sizeof(fio->erasures));
354 }
355
356 /*
357 * Decode all RS blocks in a single data block and return the target block
358 * (indicated by @offset) in fio->output. If @use_erasures is non-zero, uses
359 * hashes to locate erasures.
360 */
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)361 static int fec_decode_rsb(struct dm_verity *v, struct dm_verity_io *io,
362 struct dm_verity_fec_io *fio, u64 rsb, u64 offset,
363 bool use_erasures)
364 {
365 int r, neras = 0;
366 unsigned pos;
367
368 r = fec_alloc_bufs(v, fio);
369 if (unlikely(r < 0))
370 return r;
371
372 for (pos = 0; pos < 1 << v->data_dev_block_bits; ) {
373 fec_init_bufs(v, fio);
374
375 r = fec_read_bufs(v, io, rsb, offset, pos,
376 use_erasures ? &neras : NULL);
377 if (unlikely(r < 0))
378 return r;
379
380 r = fec_decode_bufs(v, fio, rsb, r, pos, neras);
381 if (r < 0)
382 return r;
383
384 pos += fio->nbufs << DM_VERITY_FEC_BUF_RS_BITS;
385 }
386
387 /* Always re-validate the corrected block against the expected hash */
388 r = verity_hash(v, verity_io_hash_req(v, io), fio->output,
389 1 << v->data_dev_block_bits,
390 verity_io_real_digest(v, io));
391 if (unlikely(r < 0))
392 return r;
393
394 if (memcmp(verity_io_real_digest(v, io), verity_io_want_digest(v, io),
395 v->digest_size)) {
396 DMERR_LIMIT("%s: FEC %llu: failed to correct (%d erasures)",
397 v->data_dev->name, (unsigned long long)rsb, neras);
398 return -EILSEQ;
399 }
400
401 return 0;
402 }
403
fec_bv_copy(struct dm_verity * v,struct dm_verity_io * io,u8 * data,size_t len)404 static int fec_bv_copy(struct dm_verity *v, struct dm_verity_io *io, u8 *data,
405 size_t len)
406 {
407 struct dm_verity_fec_io *fio = fec_io(io);
408
409 memcpy(data, &fio->output[fio->output_pos], len);
410 fio->output_pos += len;
411
412 return 0;
413 }
414
415 /*
416 * Correct errors in a block. Copies corrected block to dest if non-NULL,
417 * otherwise to a bio_vec starting from iter.
418 */
verity_fec_decode(struct dm_verity * v,struct dm_verity_io * io,enum verity_block_type type,sector_t block,u8 * dest,struct bvec_iter * iter)419 int verity_fec_decode(struct dm_verity *v, struct dm_verity_io *io,
420 enum verity_block_type type, sector_t block, u8 *dest,
421 struct bvec_iter *iter)
422 {
423 int r;
424 struct dm_verity_fec_io *fio = fec_io(io);
425 u64 offset, res, rsb;
426
427 if (!verity_fec_is_enabled(v))
428 return -EOPNOTSUPP;
429
430 if (fio->level >= DM_VERITY_FEC_MAX_RECURSION) {
431 DMWARN_LIMIT("%s: FEC: recursion too deep", v->data_dev->name);
432 return -EIO;
433 }
434
435 fio->level++;
436
437 if (type == DM_VERITY_BLOCK_TYPE_METADATA)
438 block += v->data_blocks;
439
440 /*
441 * For RS(M, N), the continuous FEC data is divided into blocks of N
442 * bytes. Since block size may not be divisible by N, the last block
443 * is zero padded when decoding.
444 *
445 * Each byte of the block is covered by a different RS(M, N) code,
446 * and each code is interleaved over N blocks to make it less likely
447 * that bursty corruption will leave us in unrecoverable state.
448 */
449
450 offset = block << v->data_dev_block_bits;
451 res = div64_u64(offset, v->fec->rounds << v->data_dev_block_bits);
452
453 /*
454 * The base RS block we can feed to the interleaver to find out all
455 * blocks required for decoding.
456 */
457 rsb = offset - res * (v->fec->rounds << v->data_dev_block_bits);
458
459 /*
460 * Locating erasures is slow, so attempt to recover the block without
461 * them first. Do a second attempt with erasures if the corruption is
462 * bad enough.
463 */
464 r = fec_decode_rsb(v, io, fio, rsb, offset, false);
465 if (r < 0) {
466 r = fec_decode_rsb(v, io, fio, rsb, offset, true);
467 if (r < 0)
468 goto done;
469 }
470
471 if (dest)
472 memcpy(dest, fio->output, 1 << v->data_dev_block_bits);
473 else if (iter) {
474 fio->output_pos = 0;
475 r = verity_for_bv_block(v, io, iter, fec_bv_copy);
476 }
477
478 done:
479 fio->level--;
480 return r;
481 }
482
483 /*
484 * Clean up per-bio data.
485 */
verity_fec_finish_io(struct dm_verity_io * io)486 void verity_fec_finish_io(struct dm_verity_io *io)
487 {
488 unsigned n;
489 struct dm_verity_fec *f = io->v->fec;
490 struct dm_verity_fec_io *fio = fec_io(io);
491
492 if (!verity_fec_is_enabled(io->v))
493 return;
494
495 mempool_free(fio->rs, &f->rs_pool);
496
497 fec_for_each_prealloc_buffer(n)
498 mempool_free(fio->bufs[n], &f->prealloc_pool);
499
500 fec_for_each_extra_buffer(fio, n)
501 mempool_free(fio->bufs[n], &f->extra_pool);
502
503 mempool_free(fio->output, &f->output_pool);
504 }
505
506 /*
507 * Initialize per-bio data.
508 */
verity_fec_init_io(struct dm_verity_io * io)509 void verity_fec_init_io(struct dm_verity_io *io)
510 {
511 struct dm_verity_fec_io *fio = fec_io(io);
512
513 if (!verity_fec_is_enabled(io->v))
514 return;
515
516 fio->rs = NULL;
517 memset(fio->bufs, 0, sizeof(fio->bufs));
518 fio->nbufs = 0;
519 fio->output = NULL;
520 fio->level = 0;
521 }
522
523 /*
524 * Append feature arguments and values to the status table.
525 */
verity_fec_status_table(struct dm_verity * v,unsigned sz,char * result,unsigned maxlen)526 unsigned verity_fec_status_table(struct dm_verity *v, unsigned sz,
527 char *result, unsigned maxlen)
528 {
529 if (!verity_fec_is_enabled(v))
530 return sz;
531
532 DMEMIT(" " DM_VERITY_OPT_FEC_DEV " %s "
533 DM_VERITY_OPT_FEC_BLOCKS " %llu "
534 DM_VERITY_OPT_FEC_START " %llu "
535 DM_VERITY_OPT_FEC_ROOTS " %d",
536 v->fec->dev->name,
537 (unsigned long long)v->fec->blocks,
538 (unsigned long long)v->fec->start,
539 v->fec->roots);
540
541 return sz;
542 }
543
verity_fec_dtr(struct dm_verity * v)544 void verity_fec_dtr(struct dm_verity *v)
545 {
546 struct dm_verity_fec *f = v->fec;
547
548 if (!verity_fec_is_enabled(v))
549 goto out;
550
551 mempool_exit(&f->rs_pool);
552 mempool_exit(&f->prealloc_pool);
553 mempool_exit(&f->extra_pool);
554 kmem_cache_destroy(f->cache);
555
556 if (f->data_bufio)
557 dm_bufio_client_destroy(f->data_bufio);
558 if (f->bufio)
559 dm_bufio_client_destroy(f->bufio);
560
561 if (f->dev)
562 dm_put_device(v->ti, f->dev);
563 out:
564 kfree(f);
565 v->fec = NULL;
566 }
567
fec_rs_alloc(gfp_t gfp_mask,void * pool_data)568 static void *fec_rs_alloc(gfp_t gfp_mask, void *pool_data)
569 {
570 struct dm_verity *v = (struct dm_verity *)pool_data;
571
572 return init_rs_gfp(8, 0x11d, 0, 1, v->fec->roots, gfp_mask);
573 }
574
fec_rs_free(void * element,void * pool_data)575 static void fec_rs_free(void *element, void *pool_data)
576 {
577 struct rs_control *rs = (struct rs_control *)element;
578
579 if (rs)
580 free_rs(rs);
581 }
582
verity_is_fec_opt_arg(const char * arg_name)583 bool verity_is_fec_opt_arg(const char *arg_name)
584 {
585 return (!strcasecmp(arg_name, DM_VERITY_OPT_FEC_DEV) ||
586 !strcasecmp(arg_name, DM_VERITY_OPT_FEC_BLOCKS) ||
587 !strcasecmp(arg_name, DM_VERITY_OPT_FEC_START) ||
588 !strcasecmp(arg_name, DM_VERITY_OPT_FEC_ROOTS));
589 }
590
verity_fec_parse_opt_args(struct dm_arg_set * as,struct dm_verity * v,unsigned * argc,const char * arg_name)591 int verity_fec_parse_opt_args(struct dm_arg_set *as, struct dm_verity *v,
592 unsigned *argc, const char *arg_name)
593 {
594 int r;
595 struct dm_target *ti = v->ti;
596 const char *arg_value;
597 unsigned long long num_ll;
598 unsigned char num_c;
599 char dummy;
600
601 if (!*argc) {
602 ti->error = "FEC feature arguments require a value";
603 return -EINVAL;
604 }
605
606 arg_value = dm_shift_arg(as);
607 (*argc)--;
608
609 if (!strcasecmp(arg_name, DM_VERITY_OPT_FEC_DEV)) {
610 r = dm_get_device(ti, arg_value, FMODE_READ, &v->fec->dev);
611 if (r) {
612 ti->error = "FEC device lookup failed";
613 return r;
614 }
615
616 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_FEC_BLOCKS)) {
617 if (sscanf(arg_value, "%llu%c", &num_ll, &dummy) != 1 ||
618 ((sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT))
619 >> (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll)) {
620 ti->error = "Invalid " DM_VERITY_OPT_FEC_BLOCKS;
621 return -EINVAL;
622 }
623 v->fec->blocks = num_ll;
624
625 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_FEC_START)) {
626 if (sscanf(arg_value, "%llu%c", &num_ll, &dummy) != 1 ||
627 ((sector_t)(num_ll << (v->data_dev_block_bits - SECTOR_SHIFT)) >>
628 (v->data_dev_block_bits - SECTOR_SHIFT) != num_ll)) {
629 ti->error = "Invalid " DM_VERITY_OPT_FEC_START;
630 return -EINVAL;
631 }
632 v->fec->start = num_ll;
633
634 } else if (!strcasecmp(arg_name, DM_VERITY_OPT_FEC_ROOTS)) {
635 if (sscanf(arg_value, "%hhu%c", &num_c, &dummy) != 1 || !num_c ||
636 num_c < (DM_VERITY_FEC_RSM - DM_VERITY_FEC_MAX_RSN) ||
637 num_c > (DM_VERITY_FEC_RSM - DM_VERITY_FEC_MIN_RSN)) {
638 ti->error = "Invalid " DM_VERITY_OPT_FEC_ROOTS;
639 return -EINVAL;
640 }
641 v->fec->roots = num_c;
642
643 } else {
644 ti->error = "Unrecognized verity FEC feature request";
645 return -EINVAL;
646 }
647
648 return 0;
649 }
650
651 /*
652 * Allocate dm_verity_fec for v->fec. Must be called before verity_fec_ctr.
653 */
verity_fec_ctr_alloc(struct dm_verity * v)654 int verity_fec_ctr_alloc(struct dm_verity *v)
655 {
656 struct dm_verity_fec *f;
657
658 f = kzalloc(sizeof(struct dm_verity_fec), GFP_KERNEL);
659 if (!f) {
660 v->ti->error = "Cannot allocate FEC structure";
661 return -ENOMEM;
662 }
663 v->fec = f;
664
665 return 0;
666 }
667
668 /*
669 * Validate arguments and preallocate memory. Must be called after arguments
670 * have been parsed using verity_fec_parse_opt_args.
671 */
verity_fec_ctr(struct dm_verity * v)672 int verity_fec_ctr(struct dm_verity *v)
673 {
674 struct dm_verity_fec *f = v->fec;
675 struct dm_target *ti = v->ti;
676 u64 hash_blocks;
677 int ret;
678
679 if (!verity_fec_is_enabled(v)) {
680 verity_fec_dtr(v);
681 return 0;
682 }
683
684 /*
685 * FEC is computed over data blocks, possible metadata, and
686 * hash blocks. In other words, FEC covers total of fec_blocks
687 * blocks consisting of the following:
688 *
689 * data blocks | hash blocks | metadata (optional)
690 *
691 * We allow metadata after hash blocks to support a use case
692 * where all data is stored on the same device and FEC covers
693 * the entire area.
694 *
695 * If metadata is included, we require it to be available on the
696 * hash device after the hash blocks.
697 */
698
699 hash_blocks = v->hash_blocks - v->hash_start;
700
701 /*
702 * Require matching block sizes for data and hash devices for
703 * simplicity.
704 */
705 if (v->data_dev_block_bits != v->hash_dev_block_bits) {
706 ti->error = "Block sizes must match to use FEC";
707 return -EINVAL;
708 }
709
710 if (!f->roots) {
711 ti->error = "Missing " DM_VERITY_OPT_FEC_ROOTS;
712 return -EINVAL;
713 }
714 f->rsn = DM_VERITY_FEC_RSM - f->roots;
715
716 if (!f->blocks) {
717 ti->error = "Missing " DM_VERITY_OPT_FEC_BLOCKS;
718 return -EINVAL;
719 }
720
721 f->rounds = f->blocks;
722 if (sector_div(f->rounds, f->rsn))
723 f->rounds++;
724
725 /*
726 * Due to optional metadata, f->blocks can be larger than
727 * data_blocks and hash_blocks combined.
728 */
729 if (f->blocks < v->data_blocks + hash_blocks || !f->rounds) {
730 ti->error = "Invalid " DM_VERITY_OPT_FEC_BLOCKS;
731 return -EINVAL;
732 }
733
734 /*
735 * Metadata is accessed through the hash device, so we require
736 * it to be large enough.
737 */
738 f->hash_blocks = f->blocks - v->data_blocks;
739 if (dm_bufio_get_device_size(v->bufio) < f->hash_blocks) {
740 ti->error = "Hash device is too small for "
741 DM_VERITY_OPT_FEC_BLOCKS;
742 return -E2BIG;
743 }
744
745 f->bufio = dm_bufio_client_create(f->dev->bdev,
746 1 << v->data_dev_block_bits,
747 1, 0, NULL, NULL);
748 if (IS_ERR(f->bufio)) {
749 ti->error = "Cannot initialize FEC bufio client";
750 return PTR_ERR(f->bufio);
751 }
752
753 if (dm_bufio_get_device_size(f->bufio) <
754 ((f->start + f->rounds * f->roots) >> v->data_dev_block_bits)) {
755 ti->error = "FEC device is too small";
756 return -E2BIG;
757 }
758
759 f->data_bufio = dm_bufio_client_create(v->data_dev->bdev,
760 1 << v->data_dev_block_bits,
761 1, 0, NULL, NULL);
762 if (IS_ERR(f->data_bufio)) {
763 ti->error = "Cannot initialize FEC data bufio client";
764 return PTR_ERR(f->data_bufio);
765 }
766
767 if (dm_bufio_get_device_size(f->data_bufio) < v->data_blocks) {
768 ti->error = "Data device is too small";
769 return -E2BIG;
770 }
771
772 /* Preallocate an rs_control structure for each worker thread */
773 ret = mempool_init(&f->rs_pool, num_online_cpus(), fec_rs_alloc,
774 fec_rs_free, (void *) v);
775 if (ret) {
776 ti->error = "Cannot allocate RS pool";
777 return ret;
778 }
779
780 f->cache = kmem_cache_create("dm_verity_fec_buffers",
781 f->rsn << DM_VERITY_FEC_BUF_RS_BITS,
782 0, 0, NULL);
783 if (!f->cache) {
784 ti->error = "Cannot create FEC buffer cache";
785 return -ENOMEM;
786 }
787
788 /* Preallocate DM_VERITY_FEC_BUF_PREALLOC buffers for each thread */
789 ret = mempool_init_slab_pool(&f->prealloc_pool, num_online_cpus() *
790 DM_VERITY_FEC_BUF_PREALLOC,
791 f->cache);
792 if (ret) {
793 ti->error = "Cannot allocate FEC buffer prealloc pool";
794 return ret;
795 }
796
797 ret = mempool_init_slab_pool(&f->extra_pool, 0, f->cache);
798 if (ret) {
799 ti->error = "Cannot allocate FEC buffer extra pool";
800 return ret;
801 }
802
803 /* Preallocate an output buffer for each thread */
804 ret = mempool_init_kmalloc_pool(&f->output_pool, num_online_cpus(),
805 1 << v->data_dev_block_bits);
806 if (ret) {
807 ti->error = "Cannot allocate FEC output pool";
808 return ret;
809 }
810
811 /* Reserve space for our per-bio data */
812 ti->per_io_data_size += sizeof(struct dm_verity_fec_io);
813
814 return 0;
815 }
816
