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