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      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 2006 Sun Microsystems, Inc.  All rights reserved.
     23  * Use is subject to license terms.
     24  */
     25 
     26 #pragma ident	"%Z%%M%	%I%	%E% SMI"
     27 
     28 #include <sys/zfs_context.h>
     29 #include <sys/spa.h>
     30 #include <sys/zio.h>
     31 #include <sys/zio_checksum.h>
     32 
     33 /*
     34  * Checksum vectors.
     35  *
     36  * In the SPA, everything is checksummed.  We support checksum vectors
     37  * for three distinct reasons:
     38  *
     39  *   1. Different kinds of data need different levels of protection.
     40  *	For SPA metadata, we always want a very strong checksum.
     41  *	For user data, we let users make the trade-off between speed
     42  *	and checksum strength.
     43  *
     44  *   2. Cryptographic hash and MAC algorithms are an area of active research.
     45  *	It is likely that in future hash functions will be at least as strong
     46  *	as current best-of-breed, and may be substantially faster as well.
     47  *	We want the ability to take advantage of these new hashes as soon as
     48  *	they become available.
     49  *
     50  *   3. If someone develops hardware that can compute a strong hash quickly,
     51  *	we want the ability to take advantage of that hardware.
     52  *
     53  * Of course, we don't want a checksum upgrade to invalidate existing
     54  * data, so we store the checksum *function* in five bits of the DVA.
     55  * This gives us room for up to 32 different checksum functions.
     56  *
     57  * When writing a block, we always checksum it with the latest-and-greatest
     58  * checksum function of the appropriate strength.  When reading a block,
     59  * we compare the expected checksum against the actual checksum, which we
     60  * compute via the checksum function specified in the DVA encoding.
     61  */
     62 
     63 /*ARGSUSED*/
     64 static void
     65 zio_checksum_off(const void *buf, uint64_t size, zio_cksum_t *zcp)
     66 {
     67 	ZIO_SET_CHECKSUM(zcp, 0, 0, 0, 0);
     68 }
     69 
     70 zio_checksum_info_t zio_checksum_table[ZIO_CHECKSUM_FUNCTIONS] = {
     71 	{{NULL,			NULL},			0, 0,	"inherit"},
     72 	{{NULL,			NULL},			0, 0,	"on"},
     73 	{{zio_checksum_off,	zio_checksum_off},	0, 0,	"off"},
     74 	{{zio_checksum_SHA256,	zio_checksum_SHA256},	1, 1,	"label"},
     75 	{{zio_checksum_SHA256,	zio_checksum_SHA256},	1, 1,	"gang_header"},
     76 	{{fletcher_2_native,	fletcher_2_byteswap},	0, 1,	"zilog"},
     77 	{{fletcher_2_native,	fletcher_2_byteswap},	0, 0,	"fletcher2"},
     78 	{{fletcher_4_native,	fletcher_4_byteswap},	1, 0,	"fletcher4"},
     79 	{{zio_checksum_SHA256,	zio_checksum_SHA256},	1, 0,	"SHA256"},
     80 };
     81 
     82 uint8_t
     83 zio_checksum_select(uint8_t child, uint8_t parent)
     84 {
     85 	ASSERT(child < ZIO_CHECKSUM_FUNCTIONS);
     86 	ASSERT(parent < ZIO_CHECKSUM_FUNCTIONS);
     87 	ASSERT(parent != ZIO_CHECKSUM_INHERIT && parent != ZIO_CHECKSUM_ON);
     88 
     89 	if (child == ZIO_CHECKSUM_INHERIT)
     90 		return (parent);
     91 
     92 	if (child == ZIO_CHECKSUM_ON)
     93 		return (ZIO_CHECKSUM_ON_VALUE);
     94 
     95 	return (child);
     96 }
     97 
     98 /*
     99  * Generate the checksum.
    100  */
    101 void
    102 zio_checksum(uint_t checksum, zio_cksum_t *zcp, void *data, uint64_t size)
    103 {
    104 	zio_block_tail_t *zbt = (zio_block_tail_t *)((char *)data + size) - 1;
    105 	zio_checksum_info_t *ci = &zio_checksum_table[checksum];
    106 	zio_cksum_t zbt_cksum;
    107 
    108 	ASSERT(checksum < ZIO_CHECKSUM_FUNCTIONS);
    109 	ASSERT(ci->ci_func[0] != NULL);
    110 
    111 	if (ci->ci_zbt) {
    112 		*zcp = zbt->zbt_cksum;
    113 		zbt->zbt_magic = ZBT_MAGIC;
    114 		ci->ci_func[0](data, size, &zbt_cksum);
    115 		zbt->zbt_cksum = zbt_cksum;
    116 	} else {
    117 		ci->ci_func[0](data, size, zcp);
    118 	}
    119 }
    120 
    121 int
    122 zio_checksum_error(zio_t *zio)
    123 {
    124 	blkptr_t *bp = zio->io_bp;
    125 	zio_cksum_t zc = bp->blk_cksum;
    126 	uint_t checksum = BP_IS_GANG(bp) ? ZIO_CHECKSUM_GANG_HEADER :
    127 	    BP_GET_CHECKSUM(bp);
    128 	int byteswap = BP_SHOULD_BYTESWAP(bp);
    129 	void *data = zio->io_data;
    130 	uint64_t size = ZIO_GET_IOSIZE(zio);
    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 actual_cksum, expected_cksum;
    134 
    135 	if (checksum >= ZIO_CHECKSUM_FUNCTIONS || ci->ci_func[0] == NULL)
    136 		return (EINVAL);
    137 
    138 	if (ci->ci_zbt) {
    139 		if (checksum == ZIO_CHECKSUM_GANG_HEADER)
    140 			zio_set_gang_verifier(zio, &zc);
    141 
    142 		if (zbt->zbt_magic == BSWAP_64(ZBT_MAGIC)) {
    143 			expected_cksum = zbt->zbt_cksum;
    144 			byteswap_uint64_array(&expected_cksum,
    145 			    sizeof (zio_cksum_t));
    146 			zbt->zbt_cksum = zc;
    147 			byteswap_uint64_array(&zbt->zbt_cksum,
    148 			    sizeof (zio_cksum_t));
    149 			ci->ci_func[1](data, size, &actual_cksum);
    150 			zbt->zbt_cksum = expected_cksum;
    151 			byteswap_uint64_array(&zbt->zbt_cksum,
    152 			    sizeof (zio_cksum_t));
    153 		} else {
    154 			expected_cksum = zbt->zbt_cksum;
    155 			zbt->zbt_cksum = zc;
    156 			ci->ci_func[0](data, size, &actual_cksum);
    157 			zbt->zbt_cksum = expected_cksum;
    158 		}
    159 		zc = expected_cksum;
    160 	} else {
    161 		ASSERT(!BP_IS_GANG(bp));
    162 		ci->ci_func[byteswap](data, size, &actual_cksum);
    163 	}
    164 
    165 	if (!ZIO_CHECKSUM_EQUAL(actual_cksum, zc))
    166 		return (ECKSUM);
    167 
    168 	if (zio_injection_enabled && !zio->io_error)
    169 		return (zio_handle_fault_injection(zio, ECKSUM));
    170 
    171 	return (0);
    172 }
    173