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, 2016 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 <sys/abd.h> 35 #include <zfs_fletcher.h> 36 37 /* 38 * Checksum vectors. 39 * 40 * In the SPA, everything is checksummed. We support checksum vectors 41 * for three distinct reasons: 42 * 43 * 1. Different kinds of data need different levels of protection. 44 * For SPA metadata, we always want a very strong checksum. 45 * For user data, we let users make the trade-off between speed 46 * and checksum strength. 47 * 48 * 2. Cryptographic hash and MAC algorithms are an area of active research. 49 * It is likely that in future hash functions will be at least as strong 50 * as current best-of-breed, and may be substantially faster as well. 51 * We want the ability to take advantage of these new hashes as soon as 52 * they become available. 53 * 54 * 3. If someone develops hardware that can compute a strong hash quickly, 55 * we want the ability to take advantage of that hardware. 56 * 57 * Of course, we don't want a checksum upgrade to invalidate existing 58 * data, so we store the checksum *function* in eight bits of the bp. 59 * This gives us room for up to 256 different checksum functions. 60 * 61 * When writing a block, we always checksum it with the latest-and-greatest 62 * checksum function of the appropriate strength. When reading a block, 63 * we compare the expected checksum against the actual checksum, which we 64 * compute via the checksum function specified by BP_GET_CHECKSUM(bp). 65 * 66 * SALTED CHECKSUMS 67 * 68 * To enable the use of less secure hash algorithms with dedup, we 69 * introduce the notion of salted checksums (MACs, really). A salted 70 * checksum is fed both a random 256-bit value (the salt) and the data 71 * to be checksummed. This salt is kept secret (stored on the pool, but 72 * never shown to the user). Thus even if an attacker knew of collision 73 * weaknesses in the hash algorithm, they won't be able to mount a known 74 * plaintext attack on the DDT, since the actual hash value cannot be 75 * known ahead of time. How the salt is used is algorithm-specific 76 * (some might simply prefix it to the data block, others might need to 77 * utilize a full-blown HMAC). On disk the salt is stored in a ZAP 78 * object in the MOS (DMU_POOL_CHECKSUM_SALT). 79 * 80 * CONTEXT TEMPLATES 81 * 82 * Some hashing algorithms need to perform a substantial amount of 83 * initialization work (e.g. salted checksums above may need to pre-hash 84 * the salt) before being able to process data. Performing this 85 * redundant work for each block would be wasteful, so we instead allow 86 * a checksum algorithm to do the work once (the first time it's used) 87 * and then keep this pre-initialized context as a template inside the 88 * spa_t (spa_cksum_tmpls). If the zio_checksum_info_t contains 89 * non-NULL ci_tmpl_init and ci_tmpl_free callbacks, they are used to 90 * construct and destruct the pre-initialized checksum context. The 91 * pre-initialized context is then reused during each checksum 92 * invocation and passed to the checksum function. 93 */ 94 95 /*ARGSUSED*/ 96 static void 97 abd_checksum_off(abd_t *abd, uint64_t size, 98 const void *ctx_template, zio_cksum_t *zcp) 99 { 100 ZIO_SET_CHECKSUM(zcp, 0, 0, 0, 0); 101 } 102 103 /*ARGSUSED*/ 104 void 105 abd_fletcher_2_native(abd_t *abd, uint64_t size, 106 const void *ctx_template, zio_cksum_t *zcp) 107 { 108 fletcher_init(zcp); 109 (void) abd_iterate_func(abd, 0, size, 110 fletcher_2_incremental_native, zcp); 111 } 112 113 /*ARGSUSED*/ 114 void 115 abd_fletcher_2_byteswap(abd_t *abd, uint64_t size, 116 const void *ctx_template, zio_cksum_t *zcp) 117 { 118 fletcher_init(zcp); 119 (void) abd_iterate_func(abd, 0, size, 120 fletcher_2_incremental_byteswap, zcp); 121 } 122 123 /*ARGSUSED*/ 124 void 125 abd_fletcher_4_native(abd_t *abd, uint64_t size, 126 const void *ctx_template, zio_cksum_t *zcp) 127 { 128 fletcher_init(zcp); 129 (void) abd_iterate_func(abd, 0, size, 130 fletcher_4_incremental_native, zcp); 131 } 132 133 /*ARGSUSED*/ 134 void 135 abd_fletcher_4_byteswap(abd_t *abd, uint64_t size, 136 const void *ctx_template, zio_cksum_t *zcp) 137 { 138 fletcher_init(zcp); 139 (void) abd_iterate_func(abd, 0, size, 140 fletcher_4_incremental_byteswap, zcp); 141 } 142 143 zio_checksum_info_t zio_checksum_table[ZIO_CHECKSUM_FUNCTIONS] = { 144 {{NULL, NULL}, NULL, NULL, 0, "inherit"}, 145 {{NULL, NULL}, NULL, NULL, 0, "on"}, 146 {{abd_checksum_off, abd_checksum_off}, 147 NULL, NULL, 0, "off"}, 148 {{abd_checksum_SHA256, abd_checksum_SHA256}, 149 NULL, NULL, ZCHECKSUM_FLAG_METADATA | ZCHECKSUM_FLAG_EMBEDDED, 150 "label"}, 151 {{abd_checksum_SHA256, abd_checksum_SHA256}, 152 NULL, NULL, ZCHECKSUM_FLAG_METADATA | ZCHECKSUM_FLAG_EMBEDDED, 153 "gang_header"}, 154 {{abd_fletcher_2_native, abd_fletcher_2_byteswap}, 155 NULL, NULL, ZCHECKSUM_FLAG_EMBEDDED, "zilog"}, 156 {{abd_fletcher_2_native, abd_fletcher_2_byteswap}, 157 NULL, NULL, 0, "fletcher2"}, 158 {{abd_fletcher_4_native, abd_fletcher_4_byteswap}, 159 NULL, NULL, ZCHECKSUM_FLAG_METADATA, "fletcher4"}, 160 {{abd_checksum_SHA256, abd_checksum_SHA256}, 161 NULL, NULL, ZCHECKSUM_FLAG_METADATA | ZCHECKSUM_FLAG_DEDUP | 162 ZCHECKSUM_FLAG_NOPWRITE, "sha256"}, 163 {{abd_fletcher_4_native, abd_fletcher_4_byteswap}, 164 NULL, NULL, ZCHECKSUM_FLAG_EMBEDDED, "zilog2"}, 165 {{abd_checksum_off, abd_checksum_off}, 166 NULL, NULL, 0, "noparity"}, 167 {{abd_checksum_SHA512_native, abd_checksum_SHA512_byteswap}, 168 NULL, NULL, ZCHECKSUM_FLAG_METADATA | ZCHECKSUM_FLAG_DEDUP | 169 ZCHECKSUM_FLAG_NOPWRITE, "sha512"}, 170 {{abd_checksum_skein_native, abd_checksum_skein_byteswap}, 171 abd_checksum_skein_tmpl_init, abd_checksum_skein_tmpl_free, 172 ZCHECKSUM_FLAG_METADATA | ZCHECKSUM_FLAG_DEDUP | 173 ZCHECKSUM_FLAG_SALTED | ZCHECKSUM_FLAG_NOPWRITE, "skein"}, 174 {{abd_checksum_edonr_native, abd_checksum_edonr_byteswap}, 175 abd_checksum_edonr_tmpl_init, abd_checksum_edonr_tmpl_free, 176 ZCHECKSUM_FLAG_METADATA | ZCHECKSUM_FLAG_SALTED | 177 ZCHECKSUM_FLAG_NOPWRITE, "edonr"}, 178 }; 179 180 /* 181 * The flag corresponding to the "verify" in dedup=[checksum,]verify 182 * must be cleared first, so callers should use ZIO_CHECKSUM_MASK. 183 */ 184 spa_feature_t 185 zio_checksum_to_feature(enum zio_checksum cksum) 186 { 187 VERIFY((cksum & ~ZIO_CHECKSUM_MASK) == 0); 188 189 switch (cksum) { 190 case ZIO_CHECKSUM_SHA512: 191 return (SPA_FEATURE_SHA512); 192 case ZIO_CHECKSUM_SKEIN: 193 return (SPA_FEATURE_SKEIN); 194 case ZIO_CHECKSUM_EDONR: 195 return (SPA_FEATURE_EDONR); 196 } 197 return (SPA_FEATURE_NONE); 198 } 199 200 enum zio_checksum 201 zio_checksum_select(enum zio_checksum child, enum zio_checksum parent) 202 { 203 ASSERT(child < ZIO_CHECKSUM_FUNCTIONS); 204 ASSERT(parent < ZIO_CHECKSUM_FUNCTIONS); 205 ASSERT(parent != ZIO_CHECKSUM_INHERIT && parent != ZIO_CHECKSUM_ON); 206 207 if (child == ZIO_CHECKSUM_INHERIT) 208 return (parent); 209 210 if (child == ZIO_CHECKSUM_ON) 211 return (ZIO_CHECKSUM_ON_VALUE); 212 213 return (child); 214 } 215 216 enum zio_checksum 217 zio_checksum_dedup_select(spa_t *spa, enum zio_checksum child, 218 enum zio_checksum parent) 219 { 220 ASSERT((child & ZIO_CHECKSUM_MASK) < ZIO_CHECKSUM_FUNCTIONS); 221 ASSERT((parent & ZIO_CHECKSUM_MASK) < ZIO_CHECKSUM_FUNCTIONS); 222 ASSERT(parent != ZIO_CHECKSUM_INHERIT && parent != ZIO_CHECKSUM_ON); 223 224 if (child == ZIO_CHECKSUM_INHERIT) 225 return (parent); 226 227 if (child == ZIO_CHECKSUM_ON) 228 return (spa_dedup_checksum(spa)); 229 230 if (child == (ZIO_CHECKSUM_ON | ZIO_CHECKSUM_VERIFY)) 231 return (spa_dedup_checksum(spa) | ZIO_CHECKSUM_VERIFY); 232 233 ASSERT((zio_checksum_table[child & ZIO_CHECKSUM_MASK].ci_flags & 234 ZCHECKSUM_FLAG_DEDUP) || 235 (child & ZIO_CHECKSUM_VERIFY) || child == ZIO_CHECKSUM_OFF); 236 237 return (child); 238 } 239 240 /* 241 * Set the external verifier for a gang block based on <vdev, offset, txg>, 242 * a tuple which is guaranteed to be unique for the life of the pool. 243 */ 244 static void 245 zio_checksum_gang_verifier(zio_cksum_t *zcp, const blkptr_t *bp) 246 { 247 const dva_t *dva = BP_IDENTITY(bp); 248 uint64_t txg = BP_PHYSICAL_BIRTH(bp); 249 250 ASSERT(BP_IS_GANG(bp)); 251 252 ZIO_SET_CHECKSUM(zcp, DVA_GET_VDEV(dva), DVA_GET_OFFSET(dva), txg, 0); 253 } 254 255 /* 256 * Set the external verifier for a label block based on its offset. 257 * The vdev is implicit, and the txg is unknowable at pool open time -- 258 * hence the logic in vdev_uberblock_load() to find the most recent copy. 259 */ 260 static void 261 zio_checksum_label_verifier(zio_cksum_t *zcp, uint64_t offset) 262 { 263 ZIO_SET_CHECKSUM(zcp, offset, 0, 0, 0); 264 } 265 266 /* 267 * Calls the template init function of a checksum which supports context 268 * templates and installs the template into the spa_t. 269 */ 270 static void 271 zio_checksum_template_init(enum zio_checksum checksum, spa_t *spa) 272 { 273 zio_checksum_info_t *ci = &zio_checksum_table[checksum]; 274 275 if (ci->ci_tmpl_init == NULL) 276 return; 277 if (spa->spa_cksum_tmpls[checksum] != NULL) 278 return; 279 280 VERIFY(ci->ci_tmpl_free != NULL); 281 mutex_enter(&spa->spa_cksum_tmpls_lock); 282 if (spa->spa_cksum_tmpls[checksum] == NULL) { 283 spa->spa_cksum_tmpls[checksum] = 284 ci->ci_tmpl_init(&spa->spa_cksum_salt); 285 VERIFY(spa->spa_cksum_tmpls[checksum] != NULL); 286 } 287 mutex_exit(&spa->spa_cksum_tmpls_lock); 288 } 289 290 /* convenience function to update a checksum to accomodate an encryption MAC */ 291 static void 292 zio_checksum_handle_crypt(zio_cksum_t *cksum, zio_cksum_t *saved, boolean_t xor) 293 { 294 /* 295 * Weak checksums do not have their entropy spread evenly 296 * across the bits of the checksum. Therefore, when truncating 297 * a weak checksum we XOR the first 2 words with the last 2 so 298 * that we don't "lose" any entropy unnecessarily. 299 */ 300 if (xor) { 301 cksum->zc_word[0] ^= cksum->zc_word[2]; 302 cksum->zc_word[1] ^= cksum->zc_word[3]; 303 } 304 305 cksum->zc_word[2] = saved->zc_word[2]; 306 cksum->zc_word[3] = saved->zc_word[3]; 307 } 308 309 /* 310 * Generate the checksum. 311 */ 312 void 313 zio_checksum_compute(zio_t *zio, enum zio_checksum checksum, 314 abd_t *abd, uint64_t size) 315 { 316 static const uint64_t zec_magic = ZEC_MAGIC; 317 blkptr_t *bp = zio->io_bp; 318 uint64_t offset = zio->io_offset; 319 zio_checksum_info_t *ci = &zio_checksum_table[checksum]; 320 zio_cksum_t cksum, saved; 321 spa_t *spa = zio->io_spa; 322 boolean_t insecure = (ci->ci_flags & ZCHECKSUM_FLAG_DEDUP) == 0; 323 324 ASSERT((uint_t)checksum < ZIO_CHECKSUM_FUNCTIONS); 325 ASSERT(ci->ci_func[0] != NULL); 326 327 zio_checksum_template_init(checksum, spa); 328 329 if (ci->ci_flags & ZCHECKSUM_FLAG_EMBEDDED) { 330 zio_eck_t eck; 331 size_t eck_offset; 332 333 bzero(&saved, sizeof (zio_cksum_t)); 334 335 if (checksum == ZIO_CHECKSUM_ZILOG2) { 336 zil_chain_t zilc; 337 abd_copy_to_buf(&zilc, abd, sizeof (zil_chain_t)); 338 339 size = P2ROUNDUP_TYPED(zilc.zc_nused, ZIL_MIN_BLKSZ, 340 uint64_t); 341 eck = zilc.zc_eck; 342 eck_offset = offsetof(zil_chain_t, zc_eck); 343 } else { 344 eck_offset = size - sizeof (zio_eck_t); 345 abd_copy_to_buf_off(&eck, abd, eck_offset, 346 sizeof (zio_eck_t)); 347 } 348 349 if (checksum == ZIO_CHECKSUM_GANG_HEADER) { 350 zio_checksum_gang_verifier(&eck.zec_cksum, bp); 351 } else if (checksum == ZIO_CHECKSUM_LABEL) { 352 zio_checksum_label_verifier(&eck.zec_cksum, offset); 353 } else { 354 saved = eck.zec_cksum; 355 eck.zec_cksum = bp->blk_cksum; 356 } 357 358 abd_copy_from_buf_off(abd, &zec_magic, 359 eck_offset + offsetof(zio_eck_t, zec_magic), 360 sizeof (zec_magic)); 361 abd_copy_from_buf_off(abd, &eck.zec_cksum, 362 eck_offset + offsetof(zio_eck_t, zec_cksum), 363 sizeof (zio_cksum_t)); 364 365 ci->ci_func[0](abd, size, spa->spa_cksum_tmpls[checksum], 366 &cksum); 367 if (bp != NULL && BP_USES_CRYPT(bp) && 368 BP_GET_TYPE(bp) != DMU_OT_OBJSET) 369 zio_checksum_handle_crypt(&cksum, &saved, insecure); 370 371 abd_copy_from_buf_off(abd, &cksum, 372 eck_offset + offsetof(zio_eck_t, zec_cksum), 373 sizeof (zio_cksum_t)); 374 } else { 375 saved = bp->blk_cksum; 376 ci->ci_func[0](abd, size, spa->spa_cksum_tmpls[checksum], 377 &cksum); 378 if (BP_USES_CRYPT(bp) && BP_GET_TYPE(bp) != DMU_OT_OBJSET) 379 zio_checksum_handle_crypt(&cksum, &saved, insecure); 380 bp->blk_cksum = cksum; 381 } 382 } 383 384 int 385 zio_checksum_error_impl(spa_t *spa, const blkptr_t *bp, 386 enum zio_checksum checksum, abd_t *abd, uint64_t size, 387 uint64_t offset, zio_bad_cksum_t *info) 388 { 389 zio_checksum_info_t *ci = &zio_checksum_table[checksum]; 390 zio_cksum_t actual_cksum, expected_cksum; 391 zio_eck_t eck; 392 int byteswap; 393 394 if (checksum >= ZIO_CHECKSUM_FUNCTIONS || ci->ci_func[0] == NULL) 395 return (SET_ERROR(EINVAL)); 396 397 zio_checksum_template_init(checksum, spa); 398 399 if (ci->ci_flags & ZCHECKSUM_FLAG_EMBEDDED) { 400 zio_cksum_t verifier; 401 size_t eck_offset; 402 403 if (checksum == ZIO_CHECKSUM_ZILOG2) { 404 zil_chain_t zilc; 405 uint64_t nused; 406 407 abd_copy_to_buf(&zilc, abd, sizeof (zil_chain_t)); 408 409 eck = zilc.zc_eck; 410 eck_offset = offsetof(zil_chain_t, zc_eck) + 411 offsetof(zio_eck_t, zec_cksum); 412 413 if (eck.zec_magic == ZEC_MAGIC) { 414 nused = zilc.zc_nused; 415 } else if (eck.zec_magic == BSWAP_64(ZEC_MAGIC)) { 416 nused = BSWAP_64(zilc.zc_nused); 417 } else { 418 return (SET_ERROR(ECKSUM)); 419 } 420 421 if (nused > size) { 422 return (SET_ERROR(ECKSUM)); 423 } 424 425 size = P2ROUNDUP_TYPED(nused, ZIL_MIN_BLKSZ, uint64_t); 426 } else { 427 eck_offset = size - sizeof (zio_eck_t); 428 abd_copy_to_buf_off(&eck, abd, eck_offset, 429 sizeof (zio_eck_t)); 430 eck_offset += offsetof(zio_eck_t, zec_cksum); 431 } 432 433 if (checksum == ZIO_CHECKSUM_GANG_HEADER) 434 zio_checksum_gang_verifier(&verifier, bp); 435 else if (checksum == ZIO_CHECKSUM_LABEL) 436 zio_checksum_label_verifier(&verifier, offset); 437 else 438 verifier = bp->blk_cksum; 439 440 byteswap = (eck.zec_magic == BSWAP_64(ZEC_MAGIC)); 441 442 if (byteswap) 443 byteswap_uint64_array(&verifier, sizeof (zio_cksum_t)); 444 445 expected_cksum = eck.zec_cksum; 446 447 abd_copy_from_buf_off(abd, &verifier, eck_offset, 448 sizeof (zio_cksum_t)); 449 450 ci->ci_func[byteswap](abd, size, 451 spa->spa_cksum_tmpls[checksum], &actual_cksum); 452 453 abd_copy_from_buf_off(abd, &expected_cksum, eck_offset, 454 sizeof (zio_cksum_t)); 455 456 if (byteswap) { 457 byteswap_uint64_array(&expected_cksum, 458 sizeof (zio_cksum_t)); 459 } 460 } else { 461 byteswap = BP_SHOULD_BYTESWAP(bp); 462 expected_cksum = bp->blk_cksum; 463 ci->ci_func[byteswap](abd, size, 464 spa->spa_cksum_tmpls[checksum], &actual_cksum); 465 } 466 467 /* 468 * MAC checksums are a special case since half of this checksum will 469 * actually be the encryption MAC. This will be verified by the 470 * decryption process, so we just check the truncated checksum now. 471 * Objset blocks use embedded MACs so we don't truncate the checksum 472 * for them. 473 */ 474 if (bp != NULL && BP_USES_CRYPT(bp) && 475 BP_GET_TYPE(bp) != DMU_OT_OBJSET) { 476 if (!(ci->ci_flags & ZCHECKSUM_FLAG_DEDUP)) { 477 actual_cksum.zc_word[0] ^= actual_cksum.zc_word[2]; 478 actual_cksum.zc_word[1] ^= actual_cksum.zc_word[3]; 479 } 480 481 actual_cksum.zc_word[2] = 0; 482 actual_cksum.zc_word[3] = 0; 483 expected_cksum.zc_word[2] = 0; 484 expected_cksum.zc_word[3] = 0; 485 } 486 487 if (info != NULL) { 488 info->zbc_expected = expected_cksum; 489 info->zbc_actual = actual_cksum; 490 info->zbc_checksum_name = ci->ci_name; 491 info->zbc_byteswapped = byteswap; 492 info->zbc_injected = 0; 493 info->zbc_has_cksum = 1; 494 } 495 if (!ZIO_CHECKSUM_EQUAL(actual_cksum, expected_cksum)) 496 return (SET_ERROR(ECKSUM)); 497 498 return (0); 499 } 500 501 int 502 zio_checksum_error(zio_t *zio, zio_bad_cksum_t *info) 503 { 504 blkptr_t *bp = zio->io_bp; 505 uint_t checksum = (bp == NULL ? zio->io_prop.zp_checksum : 506 (BP_IS_GANG(bp) ? ZIO_CHECKSUM_GANG_HEADER : BP_GET_CHECKSUM(bp))); 507 int error; 508 uint64_t size = (bp == NULL ? zio->io_size : 509 (BP_IS_GANG(bp) ? SPA_GANGBLOCKSIZE : BP_GET_PSIZE(bp))); 510 uint64_t offset = zio->io_offset; 511 abd_t *data = zio->io_abd; 512 spa_t *spa = zio->io_spa; 513 514 error = zio_checksum_error_impl(spa, bp, checksum, data, size, 515 offset, info); 516 517 if (zio_injection_enabled && error == 0 && zio->io_error == 0) { 518 error = zio_handle_fault_injection(zio, ECKSUM); 519 if (error != 0) 520 info->zbc_injected = 1; 521 } 522 523 return (error); 524 } 525 526 /* 527 * Called by a spa_t that's about to be deallocated. This steps through 528 * all of the checksum context templates and deallocates any that were 529 * initialized using the algorithm-specific template init function. 530 */ 531 void 532 zio_checksum_templates_free(spa_t *spa) 533 { 534 for (enum zio_checksum checksum = 0; 535 checksum < ZIO_CHECKSUM_FUNCTIONS; checksum++) { 536 if (spa->spa_cksum_tmpls[checksum] != NULL) { 537 zio_checksum_info_t *ci = &zio_checksum_table[checksum]; 538 539 VERIFY(ci->ci_tmpl_free != NULL); 540 ci->ci_tmpl_free(spa->spa_cksum_tmpls[checksum]); 541 spa->spa_cksum_tmpls[checksum] = NULL; 542 } 543 } 544 } 545