external/cddl/osnet/dist/uts/common/fs/zfs/zio_checksum.c

   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 2008 Sun Microsystems, Inc.  All rights reserved.
  23  * Use is subject to license terms.
  24  */
  25
  26 #include <sys/zfs_context.h>
  27 #include <sys/spa.h>
  28 #include <sys/zio.h>
  29 #include <sys/zio_checksum.h>
  30
  31 /*
  32  * Checksum vectors.
  33  *
  34  * In the SPA, everything is checksummed.  We support checksum vectors
  35  * for three distinct reasons:
  36  *
  37  *   1. Different kinds of data need different levels of protection.
  38  *      For SPA metadata, we always want a very strong checksum.
  39  *      For user data, we let users make the trade-off between speed
  40  *      and checksum strength.
  41  *
  42  *   2. Cryptographic hash and MAC algorithms are an area of active research.
  43  *      It is likely that in future hash functions will be at least as strong
  44  *      as current best-of-breed, and may be substantially faster as well.
  45  *      We want the ability to take advantage of these new hashes as soon as
  46  *      they become available.
  47  *
  48  *   3. If someone develops hardware that can compute a strong hash quickly,
  49  *      we want the ability to take advantage of that hardware.
  50  *
  51  * Of course, we don't want a checksum upgrade to invalidate existing
  52  * data, so we store the checksum *function* in five bits of the DVA.
  53  * This gives us room for up to 32 different checksum functions.
  54  *
  55  * When writing a block, we always checksum it with the latest-and-greatest
  56  * checksum function of the appropriate strength.  When reading a block,
  57  * we compare the expected checksum against the actual checksum, which we
  58  * compute via the checksum function specified in the DVA encoding.
  59  */
  60
  61 /*ARGSUSED*/
  62 static void
  63 zio_checksum_off(const void *buf, uint64_t size, zio_cksum_t *zcp)
  64 {
  65         ZIO_SET_CHECKSUM(zcp, 0, 0, 0, 0);
  66 }
  67
  68 zio_checksum_info_t zio_checksum_table[ZIO_CHECKSUM_FUNCTIONS] = {
  69         {{NULL,                 NULL},                  0, 0,   "inherit"},
  70         {{NULL,                 NULL},                  0, 0,   "on"},
  71         {{zio_checksum_off,     zio_checksum_off},      0, 0,   "off"},
  72         {{zio_checksum_SHA256,  zio_checksum_SHA256},   1, 1,   "label"},
  73         {{zio_checksum_SHA256,  zio_checksum_SHA256},   1, 1,   "gang_header"},
  74         {{fletcher_2_native,    fletcher_2_byteswap},   0, 1,   "zilog"},
  75         {{fletcher_2_native,    fletcher_2_byteswap},   0, 0,   "fletcher2"},
  76         {{fletcher_4_native,    fletcher_4_byteswap},   1, 0,   "fletcher4"},
  77         {{zio_checksum_SHA256,  zio_checksum_SHA256},   1, 0,   "SHA256"},
  78 };
  79
  80 uint8_t
  81 zio_checksum_select(uint8_t child, uint8_t parent)
  82 {
  83         ASSERT(child < ZIO_CHECKSUM_FUNCTIONS);
  84         ASSERT(parent < ZIO_CHECKSUM_FUNCTIONS);
  85         ASSERT(parent != ZIO_CHECKSUM_INHERIT && parent != ZIO_CHECKSUM_ON);
  86
  87         if (child == ZIO_CHECKSUM_INHERIT)
  88                 return (parent);
  89
  90         if (child == ZIO_CHECKSUM_ON)
  91                 return (ZIO_CHECKSUM_ON_VALUE);
  92
  93         return (child);
  94 }
  95
  96 /*
  97  * Set the external verifier for a gang block based on <vdev, offset, txg>,
  98  * a tuple which is guaranteed to be unique for the life of the pool.
  99  */
 100 static void
 101 zio_checksum_gang_verifier(zio_cksum_t *zcp, blkptr_t *bp)
 102 {
 103         dva_t *dva = BP_IDENTITY(bp);
 104         uint64_t txg = bp->blk_birth;
 105
 106         ASSERT(BP_IS_GANG(bp));
 107
 108         ZIO_SET_CHECKSUM(zcp, DVA_GET_VDEV(dva), DVA_GET_OFFSET(dva), txg, 0);
 109 }
 110
 111 /*
 112  * Set the external verifier for a label block based on its offset.
 113  * The vdev is implicit, and the txg is unknowable at pool open time --
 114  * hence the logic in vdev_uberblock_load() to find the most recent copy.
 115  */
 116 static void
 117 zio_checksum_label_verifier(zio_cksum_t *zcp, uint64_t offset)
 118 {
 119         ZIO_SET_CHECKSUM(zcp, offset, 0, 0, 0);
 120 }
 121
 122 /*
 123  * Generate the checksum.
 124  */
 125 void
 126 zio_checksum_compute(zio_t *zio, enum zio_checksum checksum,
 127         void *data, uint64_t size)
 128 {
 129         blkptr_t *bp = zio->io_bp;
 130         uint64_t offset = zio->io_offset;
 131         zio_block_tail_t *zbt = (zio_block_tail_t *)((char *)data + size) - 1;
 132         zio_checksum_info_t *ci = &zio_checksum_table[checksum];
 133         zio_cksum_t zbt_cksum;
 134
 135         ASSERT((uint_t)checksum < ZIO_CHECKSUM_FUNCTIONS);
 136         ASSERT(ci->ci_func[0] != NULL);
 137
 138         if (ci->ci_zbt) {
 139                 if (checksum == ZIO_CHECKSUM_GANG_HEADER)
 140                         zio_checksum_gang_verifier(&zbt->zbt_cksum, bp);
 141                 else if (checksum == ZIO_CHECKSUM_LABEL)
 142                         zio_checksum_label_verifier(&zbt->zbt_cksum, offset);
 143                 else
 144                         bp->blk_cksum = zbt->zbt_cksum;
 145                 zbt->zbt_magic = ZBT_MAGIC;
 146                 ci->ci_func[0](data, size, &zbt_cksum);
 147                 zbt->zbt_cksum = zbt_cksum;
 148         } else {
 149                 ci->ci_func[0](data, size, &bp->blk_cksum);
 150         }
 151 }
 152
 153 int
 154 zio_checksum_error(zio_t *zio)
 155 {
 156         blkptr_t *bp = zio->io_bp;
 157         uint_t checksum = (bp == NULL ? zio->io_prop.zp_checksum :
 158             (BP_IS_GANG(bp) ? ZIO_CHECKSUM_GANG_HEADER : BP_GET_CHECKSUM(bp)));
 159         int byteswap;
 160         void *data = zio->io_data;
 161         uint64_t size = (bp == NULL ? zio->io_size :
 162             (BP_IS_GANG(bp) ? SPA_GANGBLOCKSIZE : BP_GET_PSIZE(bp)));
 163         uint64_t offset = zio->io_offset;
 164         zio_block_tail_t *zbt = (zio_block_tail_t *)((char *)data + size) - 1;
 165         zio_checksum_info_t *ci = &zio_checksum_table[checksum];
 166         zio_cksum_t actual_cksum, expected_cksum, verifier;
 167
 168         if (checksum >= ZIO_CHECKSUM_FUNCTIONS || ci->ci_func[0] == NULL)
 169                 return (EINVAL);
 170
 171         if (ci->ci_zbt) {
 172                 if (checksum == ZIO_CHECKSUM_GANG_HEADER)
 173                         zio_checksum_gang_verifier(&verifier, bp);
 174                 else if (checksum == ZIO_CHECKSUM_LABEL)
 175                         zio_checksum_label_verifier(&verifier, offset);
 176                 else
 177                         verifier = bp->blk_cksum;
 178
 179                 byteswap = (zbt->zbt_magic == BSWAP_64(ZBT_MAGIC));
 180
 181                 if (byteswap)
 182                         byteswap_uint64_array(&verifier, sizeof (zio_cksum_t));
 183
 184                 expected_cksum = zbt->zbt_cksum;
 185                 zbt->zbt_cksum = verifier;
 186                 ci->ci_func[byteswap](data, size, &actual_cksum);
 187                 zbt->zbt_cksum = expected_cksum;
 188
 189                 if (byteswap)
 190                         byteswap_uint64_array(&expected_cksum,
 191                             sizeof (zio_cksum_t));
 192         } else {
 193                 ASSERT(!BP_IS_GANG(bp));
 194                 byteswap = BP_SHOULD_BYTESWAP(bp);
 195                 expected_cksum = bp->blk_cksum;
 196                 ci->ci_func[byteswap](data, size, &actual_cksum);
 197         }
 198
 199         if (!ZIO_CHECKSUM_EQUAL(actual_cksum, expected_cksum))
 200                 return (ECKSUM);
 201
 202         if (zio_injection_enabled && !zio->io_error)
 203                 return (zio_handle_fault_injection(zio, ECKSUM));
 204
 205         return (0);
 206 }