zfs-builds-mm/zfs-0.8.1/module/zfs/zio_checksum.c

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2019-07-06 23:40:11 +02:00
/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2013, 2016 by Delphix. All rights reserved.
* Copyright 2013 Saso Kiselkov. All rights reserved.
*/
#include <sys/zfs_context.h>
#include <sys/spa.h>
#include <sys/spa_impl.h>
#include <sys/zio.h>
#include <sys/zio_checksum.h>
#include <sys/zil.h>
#include <sys/abd.h>
#include <zfs_fletcher.h>
/*
* Checksum vectors.
*
* In the SPA, everything is checksummed. We support checksum vectors
* for three distinct reasons:
*
* 1. Different kinds of data need different levels of protection.
* For SPA metadata, we always want a very strong checksum.
* For user data, we let users make the trade-off between speed
* and checksum strength.
*
* 2. Cryptographic hash and MAC algorithms are an area of active research.
* It is likely that in future hash functions will be at least as strong
* as current best-of-breed, and may be substantially faster as well.
* We want the ability to take advantage of these new hashes as soon as
* they become available.
*
* 3. If someone develops hardware that can compute a strong hash quickly,
* we want the ability to take advantage of that hardware.
*
* Of course, we don't want a checksum upgrade to invalidate existing
* data, so we store the checksum *function* in eight bits of the bp.
* This gives us room for up to 256 different checksum functions.
*
* When writing a block, we always checksum it with the latest-and-greatest
* checksum function of the appropriate strength. When reading a block,
* we compare the expected checksum against the actual checksum, which we
* compute via the checksum function specified by BP_GET_CHECKSUM(bp).
*
* SALTED CHECKSUMS
*
* To enable the use of less secure hash algorithms with dedup, we
* introduce the notion of salted checksums (MACs, really). A salted
* checksum is fed both a random 256-bit value (the salt) and the data
* to be checksummed. This salt is kept secret (stored on the pool, but
* never shown to the user). Thus even if an attacker knew of collision
* weaknesses in the hash algorithm, they won't be able to mount a known
* plaintext attack on the DDT, since the actual hash value cannot be
* known ahead of time. How the salt is used is algorithm-specific
* (some might simply prefix it to the data block, others might need to
* utilize a full-blown HMAC). On disk the salt is stored in a ZAP
* object in the MOS (DMU_POOL_CHECKSUM_SALT).
*
* CONTEXT TEMPLATES
*
* Some hashing algorithms need to perform a substantial amount of
* initialization work (e.g. salted checksums above may need to pre-hash
* the salt) before being able to process data. Performing this
* redundant work for each block would be wasteful, so we instead allow
* a checksum algorithm to do the work once (the first time it's used)
* and then keep this pre-initialized context as a template inside the
* spa_t (spa_cksum_tmpls). If the zio_checksum_info_t contains
* non-NULL ci_tmpl_init and ci_tmpl_free callbacks, they are used to
* construct and destruct the pre-initialized checksum context. The
* pre-initialized context is then reused during each checksum
* invocation and passed to the checksum function.
*/
/*ARGSUSED*/
static void
abd_checksum_off(abd_t *abd, uint64_t size,
const void *ctx_template, zio_cksum_t *zcp)
{
ZIO_SET_CHECKSUM(zcp, 0, 0, 0, 0);
}
/*ARGSUSED*/
void
abd_fletcher_2_native(abd_t *abd, uint64_t size,
const void *ctx_template, zio_cksum_t *zcp)
{
fletcher_init(zcp);
(void) abd_iterate_func(abd, 0, size,
fletcher_2_incremental_native, zcp);
}
/*ARGSUSED*/
void
abd_fletcher_2_byteswap(abd_t *abd, uint64_t size,
const void *ctx_template, zio_cksum_t *zcp)
{
fletcher_init(zcp);
(void) abd_iterate_func(abd, 0, size,
fletcher_2_incremental_byteswap, zcp);
}
static inline void
abd_fletcher_4_impl(abd_t *abd, uint64_t size, zio_abd_checksum_data_t *acdp)
{
fletcher_4_abd_ops.acf_init(acdp);
abd_iterate_func(abd, 0, size, fletcher_4_abd_ops.acf_iter, acdp);
fletcher_4_abd_ops.acf_fini(acdp);
}
/*ARGSUSED*/
void
abd_fletcher_4_native(abd_t *abd, uint64_t size,
const void *ctx_template, zio_cksum_t *zcp)
{
fletcher_4_ctx_t ctx;
zio_abd_checksum_data_t acd = {
.acd_byteorder = ZIO_CHECKSUM_NATIVE,
.acd_zcp = zcp,
.acd_ctx = &ctx
};
abd_fletcher_4_impl(abd, size, &acd);
}
/*ARGSUSED*/
void
abd_fletcher_4_byteswap(abd_t *abd, uint64_t size,
const void *ctx_template, zio_cksum_t *zcp)
{
fletcher_4_ctx_t ctx;
zio_abd_checksum_data_t acd = {
.acd_byteorder = ZIO_CHECKSUM_BYTESWAP,
.acd_zcp = zcp,
.acd_ctx = &ctx
};
abd_fletcher_4_impl(abd, size, &acd);
}
zio_checksum_info_t zio_checksum_table[ZIO_CHECKSUM_FUNCTIONS] = {
{{NULL, NULL}, NULL, NULL, 0, "inherit"},
{{NULL, NULL}, NULL, NULL, 0, "on"},
{{abd_checksum_off, abd_checksum_off},
NULL, NULL, 0, "off"},
{{abd_checksum_SHA256, abd_checksum_SHA256},
NULL, NULL, ZCHECKSUM_FLAG_METADATA | ZCHECKSUM_FLAG_EMBEDDED,
"label"},
{{abd_checksum_SHA256, abd_checksum_SHA256},
NULL, NULL, ZCHECKSUM_FLAG_METADATA | ZCHECKSUM_FLAG_EMBEDDED,
"gang_header"},
{{abd_fletcher_2_native, abd_fletcher_2_byteswap},
NULL, NULL, ZCHECKSUM_FLAG_EMBEDDED, "zilog"},
{{abd_fletcher_2_native, abd_fletcher_2_byteswap},
NULL, NULL, 0, "fletcher2"},
{{abd_fletcher_4_native, abd_fletcher_4_byteswap},
NULL, NULL, ZCHECKSUM_FLAG_METADATA, "fletcher4"},
{{abd_checksum_SHA256, abd_checksum_SHA256},
NULL, NULL, ZCHECKSUM_FLAG_METADATA | ZCHECKSUM_FLAG_DEDUP |
ZCHECKSUM_FLAG_NOPWRITE, "sha256"},
{{abd_fletcher_4_native, abd_fletcher_4_byteswap},
NULL, NULL, ZCHECKSUM_FLAG_EMBEDDED, "zilog2"},
{{abd_checksum_off, abd_checksum_off},
NULL, NULL, 0, "noparity"},
{{abd_checksum_SHA512_native, abd_checksum_SHA512_byteswap},
NULL, NULL, ZCHECKSUM_FLAG_METADATA | ZCHECKSUM_FLAG_DEDUP |
ZCHECKSUM_FLAG_NOPWRITE, "sha512"},
{{abd_checksum_skein_native, abd_checksum_skein_byteswap},
abd_checksum_skein_tmpl_init, abd_checksum_skein_tmpl_free,
ZCHECKSUM_FLAG_METADATA | ZCHECKSUM_FLAG_DEDUP |
ZCHECKSUM_FLAG_SALTED | ZCHECKSUM_FLAG_NOPWRITE, "skein"},
{{abd_checksum_edonr_native, abd_checksum_edonr_byteswap},
abd_checksum_edonr_tmpl_init, abd_checksum_edonr_tmpl_free,
ZCHECKSUM_FLAG_METADATA | ZCHECKSUM_FLAG_SALTED |
ZCHECKSUM_FLAG_NOPWRITE, "edonr"},
};
/*
* The flag corresponding to the "verify" in dedup=[checksum,]verify
* must be cleared first, so callers should use ZIO_CHECKSUM_MASK.
*/
spa_feature_t
zio_checksum_to_feature(enum zio_checksum cksum)
{
VERIFY((cksum & ~ZIO_CHECKSUM_MASK) == 0);
switch (cksum) {
case ZIO_CHECKSUM_SHA512:
return (SPA_FEATURE_SHA512);
case ZIO_CHECKSUM_SKEIN:
return (SPA_FEATURE_SKEIN);
case ZIO_CHECKSUM_EDONR:
return (SPA_FEATURE_EDONR);
default:
return (SPA_FEATURE_NONE);
}
}
enum zio_checksum
zio_checksum_select(enum zio_checksum child, enum zio_checksum parent)
{
ASSERT(child < ZIO_CHECKSUM_FUNCTIONS);
ASSERT(parent < ZIO_CHECKSUM_FUNCTIONS);
ASSERT(parent != ZIO_CHECKSUM_INHERIT && parent != ZIO_CHECKSUM_ON);
if (child == ZIO_CHECKSUM_INHERIT)
return (parent);
if (child == ZIO_CHECKSUM_ON)
return (ZIO_CHECKSUM_ON_VALUE);
return (child);
}
enum zio_checksum
zio_checksum_dedup_select(spa_t *spa, enum zio_checksum child,
enum zio_checksum parent)
{
ASSERT((child & ZIO_CHECKSUM_MASK) < ZIO_CHECKSUM_FUNCTIONS);
ASSERT((parent & ZIO_CHECKSUM_MASK) < ZIO_CHECKSUM_FUNCTIONS);
ASSERT(parent != ZIO_CHECKSUM_INHERIT && parent != ZIO_CHECKSUM_ON);
if (child == ZIO_CHECKSUM_INHERIT)
return (parent);
if (child == ZIO_CHECKSUM_ON)
return (spa_dedup_checksum(spa));
if (child == (ZIO_CHECKSUM_ON | ZIO_CHECKSUM_VERIFY))
return (spa_dedup_checksum(spa) | ZIO_CHECKSUM_VERIFY);
ASSERT((zio_checksum_table[child & ZIO_CHECKSUM_MASK].ci_flags &
ZCHECKSUM_FLAG_DEDUP) ||
(child & ZIO_CHECKSUM_VERIFY) || child == ZIO_CHECKSUM_OFF);
return (child);
}
/*
* Set the external verifier for a gang block based on <vdev, offset, txg>,
* a tuple which is guaranteed to be unique for the life of the pool.
*/
static void
zio_checksum_gang_verifier(zio_cksum_t *zcp, const blkptr_t *bp)
{
const dva_t *dva = BP_IDENTITY(bp);
uint64_t txg = BP_PHYSICAL_BIRTH(bp);
ASSERT(BP_IS_GANG(bp));
ZIO_SET_CHECKSUM(zcp, DVA_GET_VDEV(dva), DVA_GET_OFFSET(dva), txg, 0);
}
/*
* Set the external verifier for a label block based on its offset.
* The vdev is implicit, and the txg is unknowable at pool open time --
* hence the logic in vdev_uberblock_load() to find the most recent copy.
*/
static void
zio_checksum_label_verifier(zio_cksum_t *zcp, uint64_t offset)
{
ZIO_SET_CHECKSUM(zcp, offset, 0, 0, 0);
}
/*
* Calls the template init function of a checksum which supports context
* templates and installs the template into the spa_t.
*/
static void
zio_checksum_template_init(enum zio_checksum checksum, spa_t *spa)
{
zio_checksum_info_t *ci = &zio_checksum_table[checksum];
if (ci->ci_tmpl_init == NULL)
return;
if (spa->spa_cksum_tmpls[checksum] != NULL)
return;
VERIFY(ci->ci_tmpl_free != NULL);
mutex_enter(&spa->spa_cksum_tmpls_lock);
if (spa->spa_cksum_tmpls[checksum] == NULL) {
spa->spa_cksum_tmpls[checksum] =
ci->ci_tmpl_init(&spa->spa_cksum_salt);
VERIFY(spa->spa_cksum_tmpls[checksum] != NULL);
}
mutex_exit(&spa->spa_cksum_tmpls_lock);
}
/* convenience function to update a checksum to accomodate an encryption MAC */
static void
zio_checksum_handle_crypt(zio_cksum_t *cksum, zio_cksum_t *saved, boolean_t xor)
{
/*
* Weak checksums do not have their entropy spread evenly
* across the bits of the checksum. Therefore, when truncating
* a weak checksum we XOR the first 2 words with the last 2 so
* that we don't "lose" any entropy unnecessarily.
*/
if (xor) {
cksum->zc_word[0] ^= cksum->zc_word[2];
cksum->zc_word[1] ^= cksum->zc_word[3];
}
cksum->zc_word[2] = saved->zc_word[2];
cksum->zc_word[3] = saved->zc_word[3];
}
/*
* Generate the checksum.
*/
void
zio_checksum_compute(zio_t *zio, enum zio_checksum checksum,
abd_t *abd, uint64_t size)
{
static const uint64_t zec_magic = ZEC_MAGIC;
blkptr_t *bp = zio->io_bp;
uint64_t offset = zio->io_offset;
zio_checksum_info_t *ci = &zio_checksum_table[checksum];
zio_cksum_t cksum, saved;
spa_t *spa = zio->io_spa;
boolean_t insecure = (ci->ci_flags & ZCHECKSUM_FLAG_DEDUP) == 0;
ASSERT((uint_t)checksum < ZIO_CHECKSUM_FUNCTIONS);
ASSERT(ci->ci_func[0] != NULL);
zio_checksum_template_init(checksum, spa);
if (ci->ci_flags & ZCHECKSUM_FLAG_EMBEDDED) {
zio_eck_t eck;
size_t eck_offset;
bzero(&saved, sizeof (zio_cksum_t));
if (checksum == ZIO_CHECKSUM_ZILOG2) {
zil_chain_t zilc;
abd_copy_to_buf(&zilc, abd, sizeof (zil_chain_t));
size = P2ROUNDUP_TYPED(zilc.zc_nused, ZIL_MIN_BLKSZ,
uint64_t);
eck = zilc.zc_eck;
eck_offset = offsetof(zil_chain_t, zc_eck);
} else {
eck_offset = size - sizeof (zio_eck_t);
abd_copy_to_buf_off(&eck, abd, eck_offset,
sizeof (zio_eck_t));
}
if (checksum == ZIO_CHECKSUM_GANG_HEADER) {
zio_checksum_gang_verifier(&eck.zec_cksum, bp);
} else if (checksum == ZIO_CHECKSUM_LABEL) {
zio_checksum_label_verifier(&eck.zec_cksum, offset);
} else {
saved = eck.zec_cksum;
eck.zec_cksum = bp->blk_cksum;
}
abd_copy_from_buf_off(abd, &zec_magic,
eck_offset + offsetof(zio_eck_t, zec_magic),
sizeof (zec_magic));
abd_copy_from_buf_off(abd, &eck.zec_cksum,
eck_offset + offsetof(zio_eck_t, zec_cksum),
sizeof (zio_cksum_t));
ci->ci_func[0](abd, size, spa->spa_cksum_tmpls[checksum],
&cksum);
if (bp != NULL && BP_USES_CRYPT(bp) &&
BP_GET_TYPE(bp) != DMU_OT_OBJSET)
zio_checksum_handle_crypt(&cksum, &saved, insecure);
abd_copy_from_buf_off(abd, &cksum,
eck_offset + offsetof(zio_eck_t, zec_cksum),
sizeof (zio_cksum_t));
} else {
saved = bp->blk_cksum;
ci->ci_func[0](abd, size, spa->spa_cksum_tmpls[checksum],
&cksum);
if (BP_USES_CRYPT(bp) && BP_GET_TYPE(bp) != DMU_OT_OBJSET)
zio_checksum_handle_crypt(&cksum, &saved, insecure);
bp->blk_cksum = cksum;
}
}
int
zio_checksum_error_impl(spa_t *spa, const blkptr_t *bp,
enum zio_checksum checksum, abd_t *abd, uint64_t size, uint64_t offset,
zio_bad_cksum_t *info)
{
zio_checksum_info_t *ci = &zio_checksum_table[checksum];
zio_cksum_t actual_cksum, expected_cksum;
zio_eck_t eck;
int byteswap;
if (checksum >= ZIO_CHECKSUM_FUNCTIONS || ci->ci_func[0] == NULL)
return (SET_ERROR(EINVAL));
zio_checksum_template_init(checksum, spa);
if (ci->ci_flags & ZCHECKSUM_FLAG_EMBEDDED) {
zio_cksum_t verifier;
size_t eck_offset;
if (checksum == ZIO_CHECKSUM_ZILOG2) {
zil_chain_t zilc;
uint64_t nused;
abd_copy_to_buf(&zilc, abd, sizeof (zil_chain_t));
eck = zilc.zc_eck;
eck_offset = offsetof(zil_chain_t, zc_eck) +
offsetof(zio_eck_t, zec_cksum);
if (eck.zec_magic == ZEC_MAGIC) {
nused = zilc.zc_nused;
} else if (eck.zec_magic == BSWAP_64(ZEC_MAGIC)) {
nused = BSWAP_64(zilc.zc_nused);
} else {
return (SET_ERROR(ECKSUM));
}
if (nused > size) {
return (SET_ERROR(ECKSUM));
}
size = P2ROUNDUP_TYPED(nused, ZIL_MIN_BLKSZ, uint64_t);
} else {
eck_offset = size - sizeof (zio_eck_t);
abd_copy_to_buf_off(&eck, abd, eck_offset,
sizeof (zio_eck_t));
eck_offset += offsetof(zio_eck_t, zec_cksum);
}
if (checksum == ZIO_CHECKSUM_GANG_HEADER)
zio_checksum_gang_verifier(&verifier, bp);
else if (checksum == ZIO_CHECKSUM_LABEL)
zio_checksum_label_verifier(&verifier, offset);
else
verifier = bp->blk_cksum;
byteswap = (eck.zec_magic == BSWAP_64(ZEC_MAGIC));
if (byteswap)
byteswap_uint64_array(&verifier, sizeof (zio_cksum_t));
expected_cksum = eck.zec_cksum;
abd_copy_from_buf_off(abd, &verifier, eck_offset,
sizeof (zio_cksum_t));
ci->ci_func[byteswap](abd, size,
spa->spa_cksum_tmpls[checksum], &actual_cksum);
abd_copy_from_buf_off(abd, &expected_cksum, eck_offset,
sizeof (zio_cksum_t));
if (byteswap) {
byteswap_uint64_array(&expected_cksum,
sizeof (zio_cksum_t));
}
} else {
byteswap = BP_SHOULD_BYTESWAP(bp);
expected_cksum = bp->blk_cksum;
ci->ci_func[byteswap](abd, size,
spa->spa_cksum_tmpls[checksum], &actual_cksum);
}
/*
* MAC checksums are a special case since half of this checksum will
* actually be the encryption MAC. This will be verified by the
* decryption process, so we just check the truncated checksum now.
* Objset blocks use embedded MACs so we don't truncate the checksum
* for them.
*/
if (bp != NULL && BP_USES_CRYPT(bp) &&
BP_GET_TYPE(bp) != DMU_OT_OBJSET) {
if (!(ci->ci_flags & ZCHECKSUM_FLAG_DEDUP)) {
actual_cksum.zc_word[0] ^= actual_cksum.zc_word[2];
actual_cksum.zc_word[1] ^= actual_cksum.zc_word[3];
}
actual_cksum.zc_word[2] = 0;
actual_cksum.zc_word[3] = 0;
expected_cksum.zc_word[2] = 0;
expected_cksum.zc_word[3] = 0;
}
if (info != NULL) {
info->zbc_expected = expected_cksum;
info->zbc_actual = actual_cksum;
info->zbc_checksum_name = ci->ci_name;
info->zbc_byteswapped = byteswap;
info->zbc_injected = 0;
info->zbc_has_cksum = 1;
}
if (!ZIO_CHECKSUM_EQUAL(actual_cksum, expected_cksum))
return (SET_ERROR(ECKSUM));
return (0);
}
int
zio_checksum_error(zio_t *zio, zio_bad_cksum_t *info)
{
blkptr_t *bp = zio->io_bp;
uint_t checksum = (bp == NULL ? zio->io_prop.zp_checksum :
(BP_IS_GANG(bp) ? ZIO_CHECKSUM_GANG_HEADER : BP_GET_CHECKSUM(bp)));
int error;
uint64_t size = (bp == NULL ? zio->io_size :
(BP_IS_GANG(bp) ? SPA_GANGBLOCKSIZE : BP_GET_PSIZE(bp)));
uint64_t offset = zio->io_offset;
abd_t *data = zio->io_abd;
spa_t *spa = zio->io_spa;
error = zio_checksum_error_impl(spa, bp, checksum, data, size,
offset, info);
if (zio_injection_enabled && error == 0 && zio->io_error == 0) {
error = zio_handle_fault_injection(zio, ECKSUM);
if (error != 0)
info->zbc_injected = 1;
}
return (error);
}
/*
* Called by a spa_t that's about to be deallocated. This steps through
* all of the checksum context templates and deallocates any that were
* initialized using the algorithm-specific template init function.
*/
void
zio_checksum_templates_free(spa_t *spa)
{
for (enum zio_checksum checksum = 0;
checksum < ZIO_CHECKSUM_FUNCTIONS; checksum++) {
if (spa->spa_cksum_tmpls[checksum] != NULL) {
zio_checksum_info_t *ci = &zio_checksum_table[checksum];
VERIFY(ci->ci_tmpl_free != NULL);
ci->ci_tmpl_free(spa->spa_cksum_tmpls[checksum]);
spa->spa_cksum_tmpls[checksum] = NULL;
}
}
}