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 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 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 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 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 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 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 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 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 296 zio_checksum_error_impl(spa_t *spa, blkptr_t *bp, enum zio_checksum checksum, 297 void *data, uint64_t size, uint64_t offset, zio_bad_cksum_t *info) 298 { 299 zio_checksum_info_t *ci = &zio_checksum_table[checksum]; 300 zio_cksum_t actual_cksum, expected_cksum; 301 int byteswap; 302 303 if (checksum >= ZIO_CHECKSUM_FUNCTIONS || ci->ci_func[0] == NULL) 304 return (SET_ERROR(EINVAL)); 305 306 zio_checksum_template_init(checksum, spa); 307 308 if (ci->ci_flags & ZCHECKSUM_FLAG_EMBEDDED) { 309 zio_eck_t *eck; 310 zio_cksum_t verifier; 311 312 if (checksum == ZIO_CHECKSUM_ZILOG2) { 313 zil_chain_t *zilc = data; 314 uint64_t nused; 315 316 eck = &zilc->zc_eck; 317 if (eck->zec_magic == ZEC_MAGIC) 318 nused = zilc->zc_nused; 319 else if (eck->zec_magic == BSWAP_64(ZEC_MAGIC)) 320 nused = BSWAP_64(zilc->zc_nused); 321 else 322 return (SET_ERROR(ECKSUM)); 323 324 if (nused > size) 325 return (SET_ERROR(ECKSUM)); 326 327 size = P2ROUNDUP_TYPED(nused, ZIL_MIN_BLKSZ, uint64_t); 328 } else { 329 eck = (zio_eck_t *)((char *)data + size) - 1; 330 } 331 332 if (checksum == ZIO_CHECKSUM_GANG_HEADER) 333 zio_checksum_gang_verifier(&verifier, bp); 334 else if (checksum == ZIO_CHECKSUM_LABEL) 335 zio_checksum_label_verifier(&verifier, offset); 336 else 337 verifier = bp->blk_cksum; 338 339 byteswap = (eck->zec_magic == BSWAP_64(ZEC_MAGIC)); 340 341 if (byteswap) 342 byteswap_uint64_array(&verifier, sizeof (zio_cksum_t)); 343 344 expected_cksum = eck->zec_cksum; 345 eck->zec_cksum = verifier; 346 ci->ci_func[byteswap](data, size, 347 spa->spa_cksum_tmpls[checksum], &actual_cksum); 348 eck->zec_cksum = expected_cksum; 349 350 if (byteswap) { 351 byteswap_uint64_array(&expected_cksum, 352 sizeof (zio_cksum_t)); 353 } 354 } else { 355 byteswap = BP_SHOULD_BYTESWAP(bp); 356 expected_cksum = bp->blk_cksum; 357 ci->ci_func[byteswap](data, size, 358 spa->spa_cksum_tmpls[checksum], &actual_cksum); 359 } 360 361 if (info != NULL) { 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 } 369 370 if (!ZIO_CHECKSUM_EQUAL(actual_cksum, expected_cksum)) 371 return (SET_ERROR(ECKSUM)); 372 373 return (0); 374 } 375 376 int 377 zio_checksum_error(zio_t *zio, zio_bad_cksum_t *info) 378 { 379 blkptr_t *bp = zio->io_bp; 380 uint_t checksum = (bp == NULL ? zio->io_prop.zp_checksum : 381 (BP_IS_GANG(bp) ? ZIO_CHECKSUM_GANG_HEADER : BP_GET_CHECKSUM(bp))); 382 int error; 383 uint64_t size = (bp == NULL ? zio->io_size : 384 (BP_IS_GANG(bp) ? SPA_GANGBLOCKSIZE : BP_GET_PSIZE(bp))); 385 uint64_t offset = zio->io_offset; 386 void *data = zio->io_data; 387 spa_t *spa = zio->io_spa; 388 389 error = zio_checksum_error_impl(spa, bp, checksum, data, size, 390 offset, info); 391 if (error != 0 && zio_injection_enabled && !zio->io_error && 392 (error = zio_handle_fault_injection(zio, ECKSUM)) != 0) { 393 394 info->zbc_injected = 1; 395 return (error); 396 } 397 return (error); 398 } 399 400 /* 401 * Called by a spa_t that's about to be deallocated. This steps through 402 * all of the checksum context templates and deallocates any that were 403 * initialized using the algorithm-specific template init function. 404 */ 405 void 406 zio_checksum_templates_free(spa_t *spa) 407 { 408 for (enum zio_checksum checksum = 0; 409 checksum < ZIO_CHECKSUM_FUNCTIONS; checksum++) { 410 if (spa->spa_cksum_tmpls[checksum] != NULL) { 411 zio_checksum_info_t *ci = &zio_checksum_table[checksum]; 412 413 VERIFY(ci->ci_tmpl_free != NULL); 414 ci->ci_tmpl_free(spa->spa_cksum_tmpls[checksum]); 415 spa->spa_cksum_tmpls[checksum] = NULL; 416 } 417 } 418 } 419