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freebsd-nq/module/zfs/zio_checksum.c
Tom Caputi b525630342 Native Encryption for ZFS on Linux 
This change incorporates three major pieces:

The first change is a keystore that manages wrapping
and encryption keys for encrypted datasets. These
commands mostly involve manipulating the new
DSL Crypto Key ZAP Objects that live in the MOS. Each
encrypted dataset has its own DSL Crypto Key that is
protected with a user's key. This level of indirection
allows users to change their keys without re-encrypting
their entire datasets. The change implements the new
subcommands "zfs load-key", "zfs unload-key" and
"zfs change-key" which allow the user to manage their
encryption keys and settings. In addition, several new
flags and properties have been added to allow dataset
creation and to make mounting and unmounting more
convenient.

The second piece of this patch provides the ability to
encrypt, decyrpt, and authenticate protected datasets.
Each object set maintains a Merkel tree of Message
Authentication Codes that protect the lower layers,
similarly to how checksums are maintained. This part
impacts the zio layer, which handles the actual
encryption and generation of MACs, as well as the ARC
and DMU, which need to be able to handle encrypted
buffers and protected data.

The last addition is the ability to do raw, encrypted
sends and receives. The idea here is to send raw
encrypted and compressed data and receive it exactly
as is on a backup system. This means that the dataset
on the receiving system is protected using the same
user key that is in use on the sending side. By doing
so, datasets can be efficiently backed up to an
untrusted system without fear of data being
compromised.

Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Jorgen Lundman <lundman@lundman.net>
Signed-off-by: Tom Caputi <tcaputi@datto.com>
Closes #494 
Closes #5769
2017-08-14 10:36:48 -07:00

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/*
* 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)
{
enum zio_checksum checksum;
for (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;
}
}
}
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