1 /*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21 /*
22 * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
23 * Copyright (c) 2013, 2015 by Delphix. All rights reserved.
24 * Copyright (c) 2013, Joyent, Inc. All rights reserved.
25 * Copyright 2013 Saso Kiselkov. All rights reserved.
26 */
27
28 #include <sys/zfs_context.h>
29 #include <sys/spa.h>
30 #include <sys/spa_impl.h>
31 #include <sys/zio.h>
32 #include <sys/zio_checksum.h>
33 #include <sys/zil.h>
34 #include <zfs_fletcher.h>
35
36 /*
37 * Checksum vectors.
38 *
39 * In the SPA, everything is checksummed. We support checksum vectors
40 * for three distinct reasons:
41 *
42 * 1. Different kinds of data need different levels of protection.
43 * For SPA metadata, we always want a very strong checksum.
44 * For user data, we let users make the trade-off between speed
45 * and checksum strength.
46 *
47 * 2. Cryptographic hash and MAC algorithms are an area of active research.
48 * It is likely that in future hash functions will be at least as strong
49 * as current best-of-breed, and may be substantially faster as well.
50 * We want the ability to take advantage of these new hashes as soon as
51 * they become available.
52 *
53 * 3. If someone develops hardware that can compute a strong hash quickly,
54 * we want the ability to take advantage of that hardware.
55 *
56 * Of course, we don't want a checksum upgrade to invalidate existing
57 * data, so we store the checksum *function* in eight bits of the bp.
58 * This gives us room for up to 256 different checksum functions.
59 *
60 * When writing a block, we always checksum it with the latest-and-greatest
61 * checksum function of the appropriate strength. When reading a block,
62 * we compare the expected checksum against the actual checksum, which we
63 * compute via the checksum function specified by BP_GET_CHECKSUM(bp).
64 *
65 * SALTED CHECKSUMS
66 *
67 * To enable the use of less secure hash algorithms with dedup, we
68 * introduce the notion of salted checksums (MACs, really). A salted
69 * checksum is fed both a random 256-bit value (the salt) and the data
70 * to be checksummed. This salt is kept secret (stored on the pool, but
71 * never shown to the user). Thus even if an attacker knew of collision
72 * weaknesses in the hash algorithm, they won't be able to mount a known
73 * plaintext attack on the DDT, since the actual hash value cannot be
74 * known ahead of time. How the salt is used is algorithm-specific
75 * (some might simply prefix it to the data block, others might need to
76 * utilize a full-blown HMAC). On disk the salt is stored in a ZAP
77 * object in the MOS (DMU_POOL_CHECKSUM_SALT).
78 *
79 * CONTEXT TEMPLATES
80 *
81 * Some hashing algorithms need to perform a substantial amount of
82 * initialization work (e.g. salted checksums above may need to pre-hash
83 * the salt) before being able to process data. Performing this
84 * redundant work for each block would be wasteful, so we instead allow
85 * a checksum algorithm to do the work once (the first time it's used)
86 * and then keep this pre-initialized context as a template inside the
87 * spa_t (spa_cksum_tmpls). If the zio_checksum_info_t contains
88 * non-NULL ci_tmpl_init and ci_tmpl_free callbacks, they are used to
89 * construct and destruct the pre-initialized checksum context. The
90 * pre-initialized context is then reused during each checksum
91 * invocation and passed to the checksum function.
92 */
93
94 /*ARGSUSED*/
95 static void
zio_checksum_off(const void * buf,uint64_t size,const void * ctx_template,zio_cksum_t * zcp)96 zio_checksum_off(const void *buf, uint64_t size,
97 const void *ctx_template, zio_cksum_t *zcp)
98 {
99 ZIO_SET_CHECKSUM(zcp, 0, 0, 0, 0);
100 }
101
102 zio_checksum_info_t zio_checksum_table[ZIO_CHECKSUM_FUNCTIONS] = {
103 {{NULL, NULL}, NULL, NULL, 0, "inherit"},
104 {{NULL, NULL}, NULL, NULL, 0, "on"},
105 {{zio_checksum_off, zio_checksum_off},
106 NULL, NULL, 0, "off"},
107 {{zio_checksum_SHA256, zio_checksum_SHA256},
108 NULL, NULL, ZCHECKSUM_FLAG_METADATA | ZCHECKSUM_FLAG_EMBEDDED,
109 "label"},
110 {{zio_checksum_SHA256, zio_checksum_SHA256},
111 NULL, NULL, ZCHECKSUM_FLAG_METADATA | ZCHECKSUM_FLAG_EMBEDDED,
112 "gang_header"},
113 {{fletcher_2_native, fletcher_2_byteswap},
114 NULL, NULL, ZCHECKSUM_FLAG_EMBEDDED, "zilog"},
115 {{fletcher_2_native, fletcher_2_byteswap},
116 NULL, NULL, 0, "fletcher2"},
117 {{fletcher_4_native, fletcher_4_byteswap},
118 NULL, NULL, ZCHECKSUM_FLAG_METADATA, "fletcher4"},
119 {{zio_checksum_SHA256, zio_checksum_SHA256},
120 NULL, NULL, ZCHECKSUM_FLAG_METADATA | ZCHECKSUM_FLAG_DEDUP |
121 ZCHECKSUM_FLAG_NOPWRITE, "sha256"},
122 {{fletcher_4_native, fletcher_4_byteswap},
123 NULL, NULL, ZCHECKSUM_FLAG_EMBEDDED, "zilog2"},
124 {{zio_checksum_off, zio_checksum_off},
125 NULL, NULL, 0, "noparity"},
126 {{zio_checksum_SHA512_native, zio_checksum_SHA512_byteswap},
127 NULL, NULL, ZCHECKSUM_FLAG_METADATA | ZCHECKSUM_FLAG_DEDUP |
128 ZCHECKSUM_FLAG_NOPWRITE, "sha512"},
129 {{zio_checksum_skein_native, zio_checksum_skein_byteswap},
130 zio_checksum_skein_tmpl_init, zio_checksum_skein_tmpl_free,
131 ZCHECKSUM_FLAG_METADATA | ZCHECKSUM_FLAG_DEDUP |
132 ZCHECKSUM_FLAG_SALTED | ZCHECKSUM_FLAG_NOPWRITE, "skein"},
133 {{zio_checksum_edonr_native, zio_checksum_edonr_byteswap},
134 zio_checksum_edonr_tmpl_init, zio_checksum_edonr_tmpl_free,
135 ZCHECKSUM_FLAG_METADATA | ZCHECKSUM_FLAG_SALTED |
136 ZCHECKSUM_FLAG_NOPWRITE, "edonr"},
137 };
138
139 /*
140 * The flag corresponding to the "verify" in dedup=[checksum,]verify
141 * must be cleared first, so callers should use ZIO_CHECKSUM_MASK.
142 */
143 spa_feature_t
zio_checksum_to_feature(enum zio_checksum cksum)144 zio_checksum_to_feature(enum zio_checksum cksum)
145 {
146 VERIFY((cksum & ~ZIO_CHECKSUM_MASK) == 0);
147
148 switch (cksum) {
149 case ZIO_CHECKSUM_SHA512:
150 return (SPA_FEATURE_SHA512);
151 case ZIO_CHECKSUM_SKEIN:
152 return (SPA_FEATURE_SKEIN);
153 case ZIO_CHECKSUM_EDONR:
154 return (SPA_FEATURE_EDONR);
155 }
156 return (SPA_FEATURE_NONE);
157 }
158
159 enum zio_checksum
zio_checksum_select(enum zio_checksum child,enum zio_checksum parent)160 zio_checksum_select(enum zio_checksum child, enum zio_checksum parent)
161 {
162 ASSERT(child < ZIO_CHECKSUM_FUNCTIONS);
163 ASSERT(parent < ZIO_CHECKSUM_FUNCTIONS);
164 ASSERT(parent != ZIO_CHECKSUM_INHERIT && parent != ZIO_CHECKSUM_ON);
165
166 if (child == ZIO_CHECKSUM_INHERIT)
167 return (parent);
168
169 if (child == ZIO_CHECKSUM_ON)
170 return (ZIO_CHECKSUM_ON_VALUE);
171
172 return (child);
173 }
174
175 enum zio_checksum
zio_checksum_dedup_select(spa_t * spa,enum zio_checksum child,enum zio_checksum parent)176 zio_checksum_dedup_select(spa_t *spa, enum zio_checksum child,
177 enum zio_checksum parent)
178 {
179 ASSERT((child & ZIO_CHECKSUM_MASK) < ZIO_CHECKSUM_FUNCTIONS);
180 ASSERT((parent & ZIO_CHECKSUM_MASK) < ZIO_CHECKSUM_FUNCTIONS);
181 ASSERT(parent != ZIO_CHECKSUM_INHERIT && parent != ZIO_CHECKSUM_ON);
182
183 if (child == ZIO_CHECKSUM_INHERIT)
184 return (parent);
185
186 if (child == ZIO_CHECKSUM_ON)
187 return (spa_dedup_checksum(spa));
188
189 if (child == (ZIO_CHECKSUM_ON | ZIO_CHECKSUM_VERIFY))
190 return (spa_dedup_checksum(spa) | ZIO_CHECKSUM_VERIFY);
191
192 ASSERT((zio_checksum_table[child & ZIO_CHECKSUM_MASK].ci_flags &
193 ZCHECKSUM_FLAG_DEDUP) ||
194 (child & ZIO_CHECKSUM_VERIFY) || child == ZIO_CHECKSUM_OFF);
195
196 return (child);
197 }
198
199 /*
200 * Set the external verifier for a gang block based on <vdev, offset, txg>,
201 * a tuple which is guaranteed to be unique for the life of the pool.
202 */
203 static void
zio_checksum_gang_verifier(zio_cksum_t * zcp,blkptr_t * bp)204 zio_checksum_gang_verifier(zio_cksum_t *zcp, blkptr_t *bp)
205 {
206 dva_t *dva = BP_IDENTITY(bp);
207 uint64_t txg = BP_PHYSICAL_BIRTH(bp);
208
209 ASSERT(BP_IS_GANG(bp));
210
211 ZIO_SET_CHECKSUM(zcp, DVA_GET_VDEV(dva), DVA_GET_OFFSET(dva), txg, 0);
212 }
213
214 /*
215 * Set the external verifier for a label block based on its offset.
216 * The vdev is implicit, and the txg is unknowable at pool open time --
217 * hence the logic in vdev_uberblock_load() to find the most recent copy.
218 */
219 static void
zio_checksum_label_verifier(zio_cksum_t * zcp,uint64_t offset)220 zio_checksum_label_verifier(zio_cksum_t *zcp, uint64_t offset)
221 {
222 ZIO_SET_CHECKSUM(zcp, offset, 0, 0, 0);
223 }
224
225 /*
226 * Calls the template init function of a checksum which supports context
227 * templates and installs the template into the spa_t.
228 */
229 static void
zio_checksum_template_init(enum zio_checksum checksum,spa_t * spa)230 zio_checksum_template_init(enum zio_checksum checksum, spa_t *spa)
231 {
232 zio_checksum_info_t *ci = &zio_checksum_table[checksum];
233
234 if (ci->ci_tmpl_init == NULL)
235 return;
236 if (spa->spa_cksum_tmpls[checksum] != NULL)
237 return;
238
239 VERIFY(ci->ci_tmpl_free != NULL);
240 mutex_enter(&spa->spa_cksum_tmpls_lock);
241 if (spa->spa_cksum_tmpls[checksum] == NULL) {
242 spa->spa_cksum_tmpls[checksum] =
243 ci->ci_tmpl_init(&spa->spa_cksum_salt);
244 VERIFY(spa->spa_cksum_tmpls[checksum] != NULL);
245 }
246 mutex_exit(&spa->spa_cksum_tmpls_lock);
247 }
248
249 /*
250 * Generate the checksum.
251 */
252 void
zio_checksum_compute(zio_t * zio,enum zio_checksum checksum,void * data,uint64_t size)253 zio_checksum_compute(zio_t *zio, enum zio_checksum checksum,
254 void *data, uint64_t size)
255 {
256 blkptr_t *bp = zio->io_bp;
257 uint64_t offset = zio->io_offset;
258 zio_checksum_info_t *ci = &zio_checksum_table[checksum];
259 zio_cksum_t cksum;
260 spa_t *spa = zio->io_spa;
261
262 ASSERT((uint_t)checksum < ZIO_CHECKSUM_FUNCTIONS);
263 ASSERT(ci->ci_func[0] != NULL);
264
265 zio_checksum_template_init(checksum, spa);
266
267 if (ci->ci_flags & ZCHECKSUM_FLAG_EMBEDDED) {
268 zio_eck_t *eck;
269
270 if (checksum == ZIO_CHECKSUM_ZILOG2) {
271 zil_chain_t *zilc = data;
272
273 size = P2ROUNDUP_TYPED(zilc->zc_nused, ZIL_MIN_BLKSZ,
274 uint64_t);
275 eck = &zilc->zc_eck;
276 } else {
277 eck = (zio_eck_t *)((char *)data + size) - 1;
278 }
279 if (checksum == ZIO_CHECKSUM_GANG_HEADER)
280 zio_checksum_gang_verifier(&eck->zec_cksum, bp);
281 else if (checksum == ZIO_CHECKSUM_LABEL)
282 zio_checksum_label_verifier(&eck->zec_cksum, offset);
283 else
284 bp->blk_cksum = eck->zec_cksum;
285 eck->zec_magic = ZEC_MAGIC;
286 ci->ci_func[0](data, size, spa->spa_cksum_tmpls[checksum],
287 &cksum);
288 eck->zec_cksum = cksum;
289 } else {
290 ci->ci_func[0](data, size, spa->spa_cksum_tmpls[checksum],
291 &bp->blk_cksum);
292 }
293 }
294
295 int
zio_checksum_error(zio_t * zio,zio_bad_cksum_t * info)296 zio_checksum_error(zio_t *zio, zio_bad_cksum_t *info)
297 {
298 blkptr_t *bp = zio->io_bp;
299 uint_t checksum = (bp == NULL ? zio->io_prop.zp_checksum :
300 (BP_IS_GANG(bp) ? ZIO_CHECKSUM_GANG_HEADER : BP_GET_CHECKSUM(bp)));
301 int byteswap;
302 int error;
303 uint64_t size = (bp == NULL ? zio->io_size :
304 (BP_IS_GANG(bp) ? SPA_GANGBLOCKSIZE : BP_GET_PSIZE(bp)));
305 uint64_t offset = zio->io_offset;
306 void *data = zio->io_data;
307 zio_checksum_info_t *ci = &zio_checksum_table[checksum];
308 zio_cksum_t actual_cksum, expected_cksum, verifier;
309 spa_t *spa = zio->io_spa;
310
311 if (checksum >= ZIO_CHECKSUM_FUNCTIONS || ci->ci_func[0] == NULL)
312 return (SET_ERROR(EINVAL));
313
314 zio_checksum_template_init(checksum, spa);
315
316 if (ci->ci_flags & ZCHECKSUM_FLAG_EMBEDDED) {
317 zio_eck_t *eck;
318
319 if (checksum == ZIO_CHECKSUM_ZILOG2) {
320 zil_chain_t *zilc = data;
321 uint64_t nused;
322
323 eck = &zilc->zc_eck;
324 if (eck->zec_magic == ZEC_MAGIC)
325 nused = zilc->zc_nused;
326 else if (eck->zec_magic == BSWAP_64(ZEC_MAGIC))
327 nused = BSWAP_64(zilc->zc_nused);
328 else
329 return (SET_ERROR(ECKSUM));
330
331 if (nused > size)
332 return (SET_ERROR(ECKSUM));
333
334 size = P2ROUNDUP_TYPED(nused, ZIL_MIN_BLKSZ, uint64_t);
335 } else {
336 eck = (zio_eck_t *)((char *)data + size) - 1;
337 }
338
339 if (checksum == ZIO_CHECKSUM_GANG_HEADER)
340 zio_checksum_gang_verifier(&verifier, bp);
341 else if (checksum == ZIO_CHECKSUM_LABEL)
342 zio_checksum_label_verifier(&verifier, offset);
343 else
344 verifier = bp->blk_cksum;
345
346 byteswap = (eck->zec_magic == BSWAP_64(ZEC_MAGIC));
347
348 if (byteswap)
349 byteswap_uint64_array(&verifier, sizeof (zio_cksum_t));
350
351 expected_cksum = eck->zec_cksum;
352 eck->zec_cksum = verifier;
353 ci->ci_func[byteswap](data, size,
354 spa->spa_cksum_tmpls[checksum], &actual_cksum);
355 eck->zec_cksum = expected_cksum;
356
357 if (byteswap)
358 byteswap_uint64_array(&expected_cksum,
359 sizeof (zio_cksum_t));
360 } else {
361 ASSERT(!BP_IS_GANG(bp));
362 byteswap = BP_SHOULD_BYTESWAP(bp);
363 expected_cksum = bp->blk_cksum;
364 ci->ci_func[byteswap](data, size,
365 spa->spa_cksum_tmpls[checksum], &actual_cksum);
366 }
367
368 info->zbc_expected = expected_cksum;
369 info->zbc_actual = actual_cksum;
370 info->zbc_checksum_name = ci->ci_name;
371 info->zbc_byteswapped = byteswap;
372 info->zbc_injected = 0;
373 info->zbc_has_cksum = 1;
374
375 if (!ZIO_CHECKSUM_EQUAL(actual_cksum, expected_cksum))
376 return (SET_ERROR(ECKSUM));
377
378 if (zio_injection_enabled && !zio->io_error &&
379 (error = zio_handle_fault_injection(zio, ECKSUM)) != 0) {
380
381 info->zbc_injected = 1;
382 return (error);
383 }
384
385 return (0);
386 }
387
388 /*
389 * Called by a spa_t that's about to be deallocated. This steps through
390 * all of the checksum context templates and deallocates any that were
391 * initialized using the algorithm-specific template init function.
392 */
393 void
zio_checksum_templates_free(spa_t * spa)394 zio_checksum_templates_free(spa_t *spa)
395 {
396 for (enum zio_checksum checksum = 0;
397 checksum < ZIO_CHECKSUM_FUNCTIONS; checksum++) {
398 if (spa->spa_cksum_tmpls[checksum] != NULL) {
399 zio_checksum_info_t *ci = &zio_checksum_table[checksum];
400
401 VERIFY(ci->ci_tmpl_free != NULL);
402 ci->ci_tmpl_free(spa->spa_cksum_tmpls[checksum]);
403 spa->spa_cksum_tmpls[checksum] = NULL;
404 }
405 }
406 }
407