zio_checksum.c revision 307266
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*/ 95static void 96zio_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 102zio_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#ifdef illumos 127 {{zio_checksum_SHA512_native, zio_checksum_SHA512_byteswap}, 128 NULL, NULL, ZCHECKSUM_FLAG_METADATA | ZCHECKSUM_FLAG_DEDUP | 129 ZCHECKSUM_FLAG_NOPWRITE, "sha512"}, 130 {{zio_checksum_skein_native, zio_checksum_skein_byteswap}, 131 zio_checksum_skein_tmpl_init, zio_checksum_skein_tmpl_free, 132 ZCHECKSUM_FLAG_METADATA | ZCHECKSUM_FLAG_DEDUP | 133 ZCHECKSUM_FLAG_SALTED | ZCHECKSUM_FLAG_NOPWRITE, "skein"}, 134 {{zio_checksum_edonr_native, zio_checksum_edonr_byteswap}, 135 zio_checksum_edonr_tmpl_init, zio_checksum_edonr_tmpl_free, 136 ZCHECKSUM_FLAG_METADATA | ZCHECKSUM_FLAG_SALTED | 137 ZCHECKSUM_FLAG_NOPWRITE, "edonr"}, 138#endif 139}; 140 141/* 142 * The flag corresponding to the "verify" in dedup=[checksum,]verify 143 * must be cleared first, so callers should use ZIO_CHECKSUM_MASK. 144 */ 145spa_feature_t 146zio_checksum_to_feature(enum zio_checksum cksum) 147{ 148#ifdef illumos 149 VERIFY((cksum & ~ZIO_CHECKSUM_MASK) == 0); 150 151 switch (cksum) { 152 case ZIO_CHECKSUM_SHA512: 153 return (SPA_FEATURE_SHA512); 154 case ZIO_CHECKSUM_SKEIN: 155 return (SPA_FEATURE_SKEIN); 156 case ZIO_CHECKSUM_EDONR: 157 return (SPA_FEATURE_EDONR); 158 } 159#endif 160 return (SPA_FEATURE_NONE); 161} 162 163enum zio_checksum 164zio_checksum_select(enum zio_checksum child, enum zio_checksum parent) 165{ 166 ASSERT(child < ZIO_CHECKSUM_FUNCTIONS); 167 ASSERT(parent < ZIO_CHECKSUM_FUNCTIONS); 168 ASSERT(parent != ZIO_CHECKSUM_INHERIT && parent != ZIO_CHECKSUM_ON); 169 170 if (child == ZIO_CHECKSUM_INHERIT) 171 return (parent); 172 173 if (child == ZIO_CHECKSUM_ON) 174 return (ZIO_CHECKSUM_ON_VALUE); 175 176 return (child); 177} 178 179enum zio_checksum 180zio_checksum_dedup_select(spa_t *spa, enum zio_checksum child, 181 enum zio_checksum parent) 182{ 183 ASSERT((child & ZIO_CHECKSUM_MASK) < ZIO_CHECKSUM_FUNCTIONS); 184 ASSERT((parent & ZIO_CHECKSUM_MASK) < ZIO_CHECKSUM_FUNCTIONS); 185 ASSERT(parent != ZIO_CHECKSUM_INHERIT && parent != ZIO_CHECKSUM_ON); 186 187 if (child == ZIO_CHECKSUM_INHERIT) 188 return (parent); 189 190 if (child == ZIO_CHECKSUM_ON) 191 return (spa_dedup_checksum(spa)); 192 193 if (child == (ZIO_CHECKSUM_ON | ZIO_CHECKSUM_VERIFY)) 194 return (spa_dedup_checksum(spa) | ZIO_CHECKSUM_VERIFY); 195 196 ASSERT((zio_checksum_table[child & ZIO_CHECKSUM_MASK].ci_flags & 197 ZCHECKSUM_FLAG_DEDUP) || 198 (child & ZIO_CHECKSUM_VERIFY) || child == ZIO_CHECKSUM_OFF); 199 200 return (child); 201} 202 203/* 204 * Set the external verifier for a gang block based on <vdev, offset, txg>, 205 * a tuple which is guaranteed to be unique for the life of the pool. 206 */ 207static void 208zio_checksum_gang_verifier(zio_cksum_t *zcp, blkptr_t *bp) 209{ 210 dva_t *dva = BP_IDENTITY(bp); 211 uint64_t txg = BP_PHYSICAL_BIRTH(bp); 212 213 ASSERT(BP_IS_GANG(bp)); 214 215 ZIO_SET_CHECKSUM(zcp, DVA_GET_VDEV(dva), DVA_GET_OFFSET(dva), txg, 0); 216} 217 218/* 219 * Set the external verifier for a label block based on its offset. 220 * The vdev is implicit, and the txg is unknowable at pool open time -- 221 * hence the logic in vdev_uberblock_load() to find the most recent copy. 222 */ 223static void 224zio_checksum_label_verifier(zio_cksum_t *zcp, uint64_t offset) 225{ 226 ZIO_SET_CHECKSUM(zcp, offset, 0, 0, 0); 227} 228 229/* 230 * Calls the template init function of a checksum which supports context 231 * templates and installs the template into the spa_t. 232 */ 233static void 234zio_checksum_template_init(enum zio_checksum checksum, spa_t *spa) 235{ 236 zio_checksum_info_t *ci = &zio_checksum_table[checksum]; 237 238 if (ci->ci_tmpl_init == NULL) 239 return; 240 if (spa->spa_cksum_tmpls[checksum] != NULL) 241 return; 242 243 VERIFY(ci->ci_tmpl_free != NULL); 244 mutex_enter(&spa->spa_cksum_tmpls_lock); 245 if (spa->spa_cksum_tmpls[checksum] == NULL) { 246 spa->spa_cksum_tmpls[checksum] = 247 ci->ci_tmpl_init(&spa->spa_cksum_salt); 248 VERIFY(spa->spa_cksum_tmpls[checksum] != NULL); 249 } 250 mutex_exit(&spa->spa_cksum_tmpls_lock); 251} 252 253/* 254 * Generate the checksum. 255 */ 256void 257zio_checksum_compute(zio_t *zio, enum zio_checksum checksum, 258 void *data, uint64_t size) 259{ 260 blkptr_t *bp = zio->io_bp; 261 uint64_t offset = zio->io_offset; 262 zio_checksum_info_t *ci = &zio_checksum_table[checksum]; 263 zio_cksum_t cksum; 264 spa_t *spa = zio->io_spa; 265 266 ASSERT((uint_t)checksum < ZIO_CHECKSUM_FUNCTIONS); 267 ASSERT(ci->ci_func[0] != NULL); 268 269 zio_checksum_template_init(checksum, spa); 270 271 if (ci->ci_flags & ZCHECKSUM_FLAG_EMBEDDED) { 272 zio_eck_t *eck; 273 274 if (checksum == ZIO_CHECKSUM_ZILOG2) { 275 zil_chain_t *zilc = data; 276 277 size = P2ROUNDUP_TYPED(zilc->zc_nused, ZIL_MIN_BLKSZ, 278 uint64_t); 279 eck = &zilc->zc_eck; 280 } else { 281 eck = (zio_eck_t *)((char *)data + size) - 1; 282 } 283 if (checksum == ZIO_CHECKSUM_GANG_HEADER) 284 zio_checksum_gang_verifier(&eck->zec_cksum, bp); 285 else if (checksum == ZIO_CHECKSUM_LABEL) 286 zio_checksum_label_verifier(&eck->zec_cksum, offset); 287 else 288 bp->blk_cksum = eck->zec_cksum; 289 eck->zec_magic = ZEC_MAGIC; 290 ci->ci_func[0](data, size, spa->spa_cksum_tmpls[checksum], 291 &cksum); 292 eck->zec_cksum = cksum; 293 } else { 294 ci->ci_func[0](data, size, spa->spa_cksum_tmpls[checksum], 295 &bp->blk_cksum); 296 } 297} 298 299int 300zio_checksum_error_impl(spa_t *spa, blkptr_t *bp, enum zio_checksum checksum, 301 void *data, uint64_t size, uint64_t offset, zio_bad_cksum_t *info) 302{ 303 zio_checksum_info_t *ci = &zio_checksum_table[checksum]; 304 zio_cksum_t actual_cksum, expected_cksum; 305 int byteswap; 306 307 if (checksum >= ZIO_CHECKSUM_FUNCTIONS || ci->ci_func[0] == NULL) 308 return (SET_ERROR(EINVAL)); 309 310 zio_checksum_template_init(checksum, spa); 311 312 if (ci->ci_flags & ZCHECKSUM_FLAG_EMBEDDED) { 313 zio_eck_t *eck; 314 zio_cksum_t verifier; 315 316 if (checksum == ZIO_CHECKSUM_ZILOG2) { 317 zil_chain_t *zilc = data; 318 uint64_t nused; 319 320 eck = &zilc->zc_eck; 321 if (eck->zec_magic == ZEC_MAGIC) 322 nused = zilc->zc_nused; 323 else if (eck->zec_magic == BSWAP_64(ZEC_MAGIC)) 324 nused = BSWAP_64(zilc->zc_nused); 325 else 326 return (SET_ERROR(ECKSUM)); 327 328 if (nused > size) 329 return (SET_ERROR(ECKSUM)); 330 331 size = P2ROUNDUP_TYPED(nused, ZIL_MIN_BLKSZ, uint64_t); 332 } else { 333 eck = (zio_eck_t *)((char *)data + size) - 1; 334 } 335 336 if (checksum == ZIO_CHECKSUM_GANG_HEADER) 337 zio_checksum_gang_verifier(&verifier, bp); 338 else if (checksum == ZIO_CHECKSUM_LABEL) 339 zio_checksum_label_verifier(&verifier, offset); 340 else 341 verifier = bp->blk_cksum; 342 343 byteswap = (eck->zec_magic == BSWAP_64(ZEC_MAGIC)); 344 345 if (byteswap) 346 byteswap_uint64_array(&verifier, sizeof (zio_cksum_t)); 347 348 expected_cksum = eck->zec_cksum; 349 eck->zec_cksum = verifier; 350 ci->ci_func[byteswap](data, size, 351 spa->spa_cksum_tmpls[checksum], &actual_cksum); 352 eck->zec_cksum = expected_cksum; 353 354 if (byteswap) { 355 byteswap_uint64_array(&expected_cksum, 356 sizeof (zio_cksum_t)); 357 } 358 } else { 359 byteswap = BP_SHOULD_BYTESWAP(bp); 360 expected_cksum = bp->blk_cksum; 361 ci->ci_func[byteswap](data, size, 362 spa->spa_cksum_tmpls[checksum], &actual_cksum); 363 } 364 365 if (info != NULL) { 366 info->zbc_expected = expected_cksum; 367 info->zbc_actual = actual_cksum; 368 info->zbc_checksum_name = ci->ci_name; 369 info->zbc_byteswapped = byteswap; 370 info->zbc_injected = 0; 371 info->zbc_has_cksum = 1; 372 } 373 374 if (!ZIO_CHECKSUM_EQUAL(actual_cksum, expected_cksum)) 375 return (SET_ERROR(ECKSUM)); 376 377 return (0); 378} 379 380int 381zio_checksum_error(zio_t *zio, zio_bad_cksum_t *info) 382{ 383 blkptr_t *bp = zio->io_bp; 384 uint_t checksum = (bp == NULL ? zio->io_prop.zp_checksum : 385 (BP_IS_GANG(bp) ? ZIO_CHECKSUM_GANG_HEADER : BP_GET_CHECKSUM(bp))); 386 int error; 387 uint64_t size = (bp == NULL ? zio->io_size : 388 (BP_IS_GANG(bp) ? SPA_GANGBLOCKSIZE : BP_GET_PSIZE(bp))); 389 uint64_t offset = zio->io_offset; 390 void *data = zio->io_data; 391 spa_t *spa = zio->io_spa; 392 393 error = zio_checksum_error_impl(spa, bp, checksum, data, size, 394 offset, info); 395 if (error != 0 && zio_injection_enabled && !zio->io_error && 396 (error = zio_handle_fault_injection(zio, ECKSUM)) != 0) { 397 398 info->zbc_injected = 1; 399 return (error); 400 } 401 return (error); 402} 403 404/* 405 * Called by a spa_t that's about to be deallocated. This steps through 406 * all of the checksum context templates and deallocates any that were 407 * initialized using the algorithm-specific template init function. 408 */ 409void 410zio_checksum_templates_free(spa_t *spa) 411{ 412 for (enum zio_checksum checksum = 0; 413 checksum < ZIO_CHECKSUM_FUNCTIONS; checksum++) { 414 if (spa->spa_cksum_tmpls[checksum] != NULL) { 415 zio_checksum_info_t *ci = &zio_checksum_table[checksum]; 416 417 VERIFY(ci->ci_tmpl_free != NULL); 418 ci->ci_tmpl_free(spa->spa_cksum_tmpls[checksum]); 419 spa->spa_cksum_tmpls[checksum] = NULL; 420 } 421 } 422} 423