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 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 non-cryptographically secure hash algorithms in
68 * dedup we 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 to be
70 * checksummed. This salt is kept secret (stored on the pool, but never shown
71 * to the user), thus even if an attacker knew of collision weaknesses in the
72 * hash algorithm, they won't be able to mount a known plaintext attack on
73 * the DDT, since the actual hash value cannot be known ahead of time. How
74 * the salt is used is algorithm-specific (some might simply prefix it to the
75 * data block, others might need to utilize a full-blown HMAC). On disk the
76 * salt is stored in a ZAP object in the MOS (DMU_POOL_CHECKSUM_SALT).
77 *
78 * CONTEXT TEMPLATES
79 *
80 * Some hashing algorithms need to perform a substantial amount of
81 * initialization work (e.g. salted checksums above may need to pre-hash the
82 * salt) before being able to process data. Performing this redundant work
83 * for each block would be very wasteful, so we instead allow a checksum
84 * algorithm to do the work once (the first time it's used) and then keep
85 * this pre-initialized context as a template inside the spa_t
86 * (spa_cksum_tmpls). If the zio_checksum_info_t contains non-NULL
87 * ci_tmpl_init and ci_tmpl_free callbacks, they are used to construct and
88 * destruct the pre-initialized checksum context. The pre-initialized
89 * context is then reused during each checksum invocation and passed to the
90 * checksum function.
91 */
92
93 /*ARGSUSED*/
94 static void
95 zio_checksum_off(const void *buf, uint64_t size, const zio_cksum_salt_t *salt,
96 const void *ctx_template, zio_cksum_t *zcp)
97 {
98 ZIO_SET_CHECKSUM(zcp, 0, 0, 0, 0);
99 }
100
101 zio_checksum_info_t zio_checksum_table[ZIO_CHECKSUM_FUNCTIONS] = {
102 {{NULL, NULL}, NULL, NULL, 0, 0, 0, 0, "inherit"},
103 {{NULL, NULL}, NULL, NULL, 0, 0, 0, 0, "on"},
104 {{zio_checksum_off, zio_checksum_off},
105 NULL, NULL, 0, 0, 0, 0, "off"},
106 {{zio_checksum_SHA256, zio_checksum_SHA256},
107 NULL, NULL, 1, 1, 0, 0, "label"},
108 {{zio_checksum_SHA256, zio_checksum_SHA256},
109 NULL, NULL, 1, 1, 0, 0, "gang_header"},
110 {{fletcher_2_native, fletcher_2_byteswap},
111 NULL, NULL, 0, 1, 0, 0, "zilog"},
112 {{fletcher_2_native, fletcher_2_byteswap},
113 NULL, NULL, 0, 0, 0, 0, "fletcher2"},
114 {{fletcher_4_native, fletcher_4_byteswap},
115 NULL, NULL, 1, 0, 0, 0, "fletcher4"},
116 {{zio_checksum_SHA256, zio_checksum_SHA256},
117 NULL, NULL, 1, 0, 1, 0, "sha256"},
118 {{fletcher_4_native, fletcher_4_byteswap},
119 NULL, NULL, 0, 1, 0, 0, "zilog2"},
120 {{zio_checksum_off, zio_checksum_off},
121 NULL, NULL, 0, 0, 0, 0, "noparity"},
122 {{zio_checksum_SHA512_native, zio_checksum_SHA512_byteswap},
123 NULL, NULL, 1, 0, 1, 0, "sha512"},
124 {{zio_checksum_skein_native, zio_checksum_skein_byteswap},
125 zio_checksum_skein_tmpl_init, zio_checksum_skein_tmpl_free,
126 1, 0, 1, 1, "skein"},
127 {{zio_checksum_edonr_native, zio_checksum_edonr_byteswap},
128 zio_checksum_edonr_tmpl_init, zio_checksum_edonr_tmpl_free,
129 1, 0, 1, 1, "edonr"}
130 };
131
132 enum zio_checksum
133 zio_checksum_select(enum zio_checksum child, enum zio_checksum parent)
134 {
135 ASSERT(child < ZIO_CHECKSUM_FUNCTIONS);
136 ASSERT(parent < ZIO_CHECKSUM_FUNCTIONS);
137 ASSERT(parent != ZIO_CHECKSUM_INHERIT && parent != ZIO_CHECKSUM_ON);
138
139 if (child == ZIO_CHECKSUM_INHERIT)
140 return (parent);
141
142 if (child == ZIO_CHECKSUM_ON)
143 return (ZIO_CHECKSUM_ON_VALUE);
144
145 return (child);
146 }
147
148 enum zio_checksum
149 zio_checksum_dedup_select(spa_t *spa, enum zio_checksum child,
150 enum zio_checksum parent)
151 {
152 ASSERT((child & ZIO_CHECKSUM_MASK) < ZIO_CHECKSUM_FUNCTIONS);
153 ASSERT((parent & ZIO_CHECKSUM_MASK) < ZIO_CHECKSUM_FUNCTIONS);
154 ASSERT(parent != ZIO_CHECKSUM_INHERIT && parent != ZIO_CHECKSUM_ON);
155
156 if (child == ZIO_CHECKSUM_INHERIT)
157 return (parent);
158
159 if (child == ZIO_CHECKSUM_ON)
160 return (spa_dedup_checksum(spa));
161
162 if (child == (ZIO_CHECKSUM_ON | ZIO_CHECKSUM_VERIFY))
163 return (spa_dedup_checksum(spa) | ZIO_CHECKSUM_VERIFY);
164
165 ASSERT(zio_checksum_table[child & ZIO_CHECKSUM_MASK].ci_dedup ||
166 (child & ZIO_CHECKSUM_VERIFY) || child == ZIO_CHECKSUM_OFF);
167
168 return (child);
169 }
170
171 /*
172 * Set the external verifier for a gang block based on <vdev, offset, txg>,
173 * a tuple which is guaranteed to be unique for the life of the pool.
174 */
175 static void
176 zio_checksum_gang_verifier(zio_cksum_t *zcp, blkptr_t *bp)
177 {
178 dva_t *dva = BP_IDENTITY(bp);
179 uint64_t txg = BP_PHYSICAL_BIRTH(bp);
180
181 ASSERT(BP_IS_GANG(bp));
182
183 ZIO_SET_CHECKSUM(zcp, DVA_GET_VDEV(dva), DVA_GET_OFFSET(dva), txg, 0);
184 }
185
186 /*
187 * Set the external verifier for a label block based on its offset.
188 * The vdev is implicit, and the txg is unknowable at pool open time --
189 * hence the logic in vdev_uberblock_load() to find the most recent copy.
190 */
191 static void
192 zio_checksum_label_verifier(zio_cksum_t *zcp, uint64_t offset)
193 {
194 ZIO_SET_CHECKSUM(zcp, offset, 0, 0, 0);
195 }
196
197 /*
198 * Calls the template init function of a checksum which supports context
199 * templates and installs the template into the spa_t.
200 */
201 static void
202 zio_checksum_template_init(enum zio_checksum checksum, spa_t *spa)
203 {
204 zio_checksum_info_t *ci = &zio_checksum_table[checksum];
205
206 VERIFY(ci->ci_tmpl_init != NULL && ci->ci_tmpl_free != NULL);
207 mutex_enter(&spa->spa_cksum_tmpls_lock);
208 if (spa->spa_cksum_tmpls[checksum] == NULL) {
209 spa->spa_cksum_tmpls[checksum] =
210 ci->ci_tmpl_init(&spa->spa_cksum_salt);
211 VERIFY(spa->spa_cksum_tmpls[checksum] != NULL);
212 }
213 mutex_exit(&spa->spa_cksum_tmpls_lock);
214 }
215
216 /*
217 * Generate the checksum.
218 */
219 void
220 zio_checksum_compute(zio_t *zio, enum zio_checksum checksum,
221 void *data, uint64_t size)
222 {
223 blkptr_t *bp = zio->io_bp;
224 uint64_t offset = zio->io_offset;
225 zio_checksum_info_t *ci = &zio_checksum_table[checksum];
226 zio_cksum_t cksum;
227 spa_t *spa = zio->io_spa;
228
229 ASSERT((uint_t)checksum < ZIO_CHECKSUM_FUNCTIONS);
230 ASSERT(ci->ci_func[0] != NULL);
231
232 if (ci->ci_tmpl_init != NULL && spa->spa_cksum_tmpls[checksum] == NULL)
233 zio_checksum_template_init(checksum, spa);
234
235 if (ci->ci_eck) {
236 zio_eck_t *eck;
237
238 if (checksum == ZIO_CHECKSUM_ZILOG2) {
239 zil_chain_t *zilc = data;
240
241 size = P2ROUNDUP_TYPED(zilc->zc_nused, ZIL_MIN_BLKSZ,
242 uint64_t);
243 eck = &zilc->zc_eck;
244 } else {
245 eck = (zio_eck_t *)((char *)data + size) - 1;
246 }
247 if (checksum == ZIO_CHECKSUM_GANG_HEADER)
248 zio_checksum_gang_verifier(&eck->zec_cksum, bp);
249 else if (checksum == ZIO_CHECKSUM_LABEL)
250 zio_checksum_label_verifier(&eck->zec_cksum, offset);
251 else
252 bp->blk_cksum = eck->zec_cksum;
253 eck->zec_magic = ZEC_MAGIC;
254 ci->ci_func[0](data, size, &spa->spa_cksum_salt,
255 spa->spa_cksum_tmpls[checksum], &cksum);
256 eck->zec_cksum = cksum;
257 } else {
258 ci->ci_func[0](data, size, &spa->spa_cksum_salt,
259 spa->spa_cksum_tmpls[checksum], &bp->blk_cksum);
260 }
261 }
262
263 int
264 zio_checksum_error(zio_t *zio, zio_bad_cksum_t *info)
265 {
266 blkptr_t *bp = zio->io_bp;
267 uint_t checksum = (bp == NULL ? zio->io_prop.zp_checksum :
268 (BP_IS_GANG(bp) ? ZIO_CHECKSUM_GANG_HEADER : BP_GET_CHECKSUM(bp)));
269 int byteswap;
270 int error;
271 uint64_t size = (bp == NULL ? zio->io_size :
272 (BP_IS_GANG(bp) ? SPA_GANGBLOCKSIZE : BP_GET_PSIZE(bp)));
273 uint64_t offset = zio->io_offset;
274 void *data = zio->io_data;
275 zio_checksum_info_t *ci = &zio_checksum_table[checksum];
276 zio_cksum_t actual_cksum, expected_cksum, verifier;
277 spa_t *spa = zio->io_spa;
278
279 if (checksum >= ZIO_CHECKSUM_FUNCTIONS || ci->ci_func[0] == NULL)
280 return (SET_ERROR(EINVAL));
281
282 if (ci->ci_tmpl_init != NULL && spa->spa_cksum_tmpls[checksum] == NULL)
283 zio_checksum_template_init(checksum, spa);
284
285 if (ci->ci_eck) {
286 zio_eck_t *eck;
287
288 if (checksum == ZIO_CHECKSUM_ZILOG2) {
289 zil_chain_t *zilc = data;
290 uint64_t nused;
291
292 eck = &zilc->zc_eck;
293 if (eck->zec_magic == ZEC_MAGIC)
294 nused = zilc->zc_nused;
295 else if (eck->zec_magic == BSWAP_64(ZEC_MAGIC))
296 nused = BSWAP_64(zilc->zc_nused);
297 else
298 return (SET_ERROR(ECKSUM));
299
300 if (nused > size)
301 return (SET_ERROR(ECKSUM));
302
303 size = P2ROUNDUP_TYPED(nused, ZIL_MIN_BLKSZ, uint64_t);
304 } else {
305 eck = (zio_eck_t *)((char *)data + size) - 1;
306 }
307
308 if (checksum == ZIO_CHECKSUM_GANG_HEADER)
309 zio_checksum_gang_verifier(&verifier, bp);
310 else if (checksum == ZIO_CHECKSUM_LABEL)
311 zio_checksum_label_verifier(&verifier, offset);
312 else
313 verifier = bp->blk_cksum;
314
315 byteswap = (eck->zec_magic == BSWAP_64(ZEC_MAGIC));
316
317 if (byteswap)
318 byteswap_uint64_array(&verifier, sizeof (zio_cksum_t));
319
320 expected_cksum = eck->zec_cksum;
321 eck->zec_cksum = verifier;
322 ci->ci_func[byteswap](data, size, &spa->spa_cksum_salt,
323 spa->spa_cksum_tmpls[checksum], &actual_cksum);
324 eck->zec_cksum = expected_cksum;
325
326 if (byteswap)
327 byteswap_uint64_array(&expected_cksum,
328 sizeof (zio_cksum_t));
329 } else {
330 ASSERT(!BP_IS_GANG(bp));
331 byteswap = BP_SHOULD_BYTESWAP(bp);
332 expected_cksum = bp->blk_cksum;
333 ci->ci_func[byteswap](data, size, &spa->spa_cksum_salt,
334 spa->spa_cksum_tmpls[checksum], &actual_cksum);
335 }
336
337 info->zbc_expected = expected_cksum;
338 info->zbc_actual = actual_cksum;
339 info->zbc_checksum_name = ci->ci_name;
340 info->zbc_byteswapped = byteswap;
341 info->zbc_injected = 0;
342 info->zbc_has_cksum = 1;
343
344 if (!ZIO_CHECKSUM_EQUAL(actual_cksum, expected_cksum))
345 return (SET_ERROR(ECKSUM));
346
347 if (zio_injection_enabled && !zio->io_error &&
348 (error = zio_handle_fault_injection(zio, ECKSUM)) != 0) {
349
350 info->zbc_injected = 1;
351 return (error);
352 }
353
354 return (0);
355 }
356
357 /*
358 * Called by a spa_t that's about to be deallocated. This steps through
359 * all of the checksum context templates and deallocates any that were
360 * initialized using the algorithm-specific template init function.
361 */
362 void
363 zio_checksum_templates_free(spa_t *spa)
364 {
365 for (int checksum = 0; checksum < ZIO_CHECKSUM_FUNCTIONS; checksum++) {
366 if (spa->spa_cksum_tmpls[checksum] != NULL) {
367 zio_checksum_info_t *ci = &zio_checksum_table[checksum];
368
369 VERIFY(ci->ci_tmpl_free != NULL);
370 ci->ci_tmpl_free(spa->spa_cksum_tmpls[checksum]);
371 spa->spa_cksum_tmpls[checksum] = NULL;
372 }
373 }
374 }