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Re: [dm-devel] [PATCHv2 1/1] dm-integrity: integrity protection device-mapper target



Hello,

If there is no comments, what about applying the patch?

Regards,
Dmitry

On Wed, Dec 5, 2012 at 1:06 PM, Kasatkin, Dmitry
<dmitry kasatkin intel com> wrote:
> Hello,
>
> Any comments?
>
> - Dmitry
>
>
> On Mon, Nov 26, 2012 at 4:39 PM, Dmitry Kasatkin
> <dmitry kasatkin intel com> wrote:
>> Device-mapper "integrity" target provides transparent cryptographic integrity
>> protection of the underlying read-write block device using hash-based message
>> authentication codes (HMACs). HMACs can be stored on the same or different
>> block device.
>>
>> dm-integrity uses an encrypted key type, stored on the kernel keyring, to
>> obtain a secret key for use in cryptographic operations. Encrypted keys are
>> never exposed in plain text to user space. The encrypted keys are encrypted
>> using master key, which can either be a user defined or trusted key type.
>> The secret key, which is usually device specific, binds integrity data to the
>> device. As a result data blocks and corresponding HMACs cannot simply be
>> copied over from other file systems.
>>
>> Signed-off-by: Dmitry Kasatkin <dmitry kasatkin intel com>
>> ---
>>  Documentation/device-mapper/dm-integrity.txt |  137 ++++
>>  drivers/md/Kconfig                           |   13 +
>>  drivers/md/Makefile                          |    1 +
>>  drivers/md/dm-integrity.c                    | 1050 ++++++++++++++++++++++++++
>>  4 files changed, 1201 insertions(+)
>>  create mode 100644 Documentation/device-mapper/dm-integrity.txt
>>  create mode 100644 drivers/md/dm-integrity.c
>>
>> diff --git a/Documentation/device-mapper/dm-integrity.txt b/Documentation/device-mapper/dm-integrity.txt
>> new file mode 100644
>> index 0000000..394242f
>> --- /dev/null
>> +++ b/Documentation/device-mapper/dm-integrity.txt
>> @@ -0,0 +1,137 @@
>> +dm-integrity
>> +===============
>> +
>> +Device-mapper "integrity" target provides transparent cryptographic integrity
>> +protection of the underlying read-write block device using hash-based message
>> +authentication codes (HMACs). HMACs can be stored on the same or different
>> +block device.
>> +
>> +dm-integrity uses an encrypted key type, stored on the kernel keyring, to
>> +obtain a secret key for use in cryptographic operations. Encrypted keys are
>> +never exposed in plain text to user space. The encrypted keys are encrypted
>> +using master key, which can either be a user defined or trusted key type.
>> +The secret key, which is usually device specific, binds integrity data to the
>> +device. As a result data blocks and corresponding HMACs cannot simply be
>> +copied over from other file systems.
>> +
>> +Parameters:
>> +<dev> <bs> <start> <hdev> <hbs> <hstart> <hash_algo> <hmac_algo> <key_desc> \
>> +[<opt_params>]
>> +
>> +<dev>
>> +    This is the device that is going to be used to store the data.
>> +    You can specify it as a path like /dev/xxx or a device <major>:<minor>
>> +    number.
>> +
>> +<bs>
>> +    Device block size.
>> +
>> +<start>
>> +    Starting sector within the device where data begins.
>> +
>> +<hdev>
>> +    This is the device that is going to be used to store integrity data.
>> +    You can specify it as a path like /dev/xxx or a device <major>:<minor>
>> +    number.
>> +
>> +<hbs>
>> +    HMAC device block size.
>> +
>> +<hstart>
>> +    Starting sector within the device where integrity data begins.
>> +
>> +<hash_algo>
>> +    Hash algorithm (sha1, sha256, etc).
>> +
>> +<hmac_algo>
>> +    HMAC algorithm, e.g. hmac(sha1), hmac(sha256), etc.
>> +
>> +<key_desc>
>> +    Description is a name of a key in the kernel keyring.
>> +
>> +<opt_params>
>> +    fix=1|0 - enable fix mode
>> +               In fix mode, incorrect hmacs are replaced with correct ones.
>> +               It is used for device initialization and debugging.
>> +
>> +    stats=1|0 - turns on collecting additional statistical information.
>> +               It is used to find out resource usage to tune memory pool
>> +               and queue sizes for particular use case.
>> +
>> +    verbose=1|0 - prints block number, collected hmac and stored hmac.
>> +               It is used for addition debug output.
>> +
>> +
>> +Determine the size of integrity/hmac device
>> +===============
>> +
>> +Every block device has corresponding hmac.
>> +While NIST does recommend to use sha256 hash algorithm instead of SHA1,
>> +this does not apply to hmac(sha1), because of keying. It is safe to use
>> +hmac(sha1), because it takes much less space and it is faster to calculate.
>> +hmac(sha1) size is 20 bytes. So every 4k block on the integrity device can
>> +store 204 hmacs. In order to get the required size of the integrity device,
>> +it is necessary to divide data device size by 204. See examples bellow how
>> +to do it from script.
>> +
>> +Example scripts
>> +===============
>> +
>> +1. Setting up integrity target using data and hmac store on the same block device.
>> +
>> +[[
>> +#!/bin/sh
>> +
>> +bdev=$1
>> +
>> +# block device size
>> +dsize=`blockdev --getsize $bdev`
>> +# block size
>> +bs=4096
>> +# sector to block shift
>> +sbs=3
>> +# integrity record size (hmac size)
>> +hmac=20
>> +# hmacs per block
>> +hpb=$((bs/hmac))
>> +# target device size
>> +size=$((((dsize>>sbs)*hpb/(hpb+1))<<sbs))
>> +
>> +# load the key - in this example we just use test key
>> +keyctl add user kmk "testing123" @u
>> +keyctl add encrypted dm-int-key "load `cat /etc/keys/dm-int-key`" @u
>> +
>> +# creating the target
>> +table="0 $size integrity $bdev 4096 0 $bdev 4096 $size sha1 hmac(sha1) dm-int-key"
>> +dmsetup create dm-int --table "$table"
>> +
>> +# mounting
>> +mount /dev/mapper/dm-int /mnt
>> +
>> +]]
>> +
>> +2. Setting up integrity target using data and hmac store on different block devices.
>> +
>> +[[
>> +#!/bin/sh
>> +
>> +bdev=$1
>> +hdev=$2
>> +
>> +# get size of the block device
>> +dsize=`blockdev --getsz $bdev`
>> +# round down the size to 4k blocks
>> +dsize=$((dsize & ~7))
>> +
>> +# load the key - in this example we just use test key
>> +keyctl add user kmk "testing123" @u
>> +keyctl add encrypted dm-int-key "load `cat /etc/keys/dm-int-key`" @u
>> +
>> +# creating the target
>> +table="0 $dsize integrity $bdev 4096 0 $hdev 4096 0 sha1 hmac(sha1) dm-int-key"
>> +dmsetup create dm-int --table "$table"
>> +
>> +# mounting
>> +mount /dev/mapper/dm-int /mnt
>> +
>> +]]
>> diff --git a/drivers/md/Kconfig b/drivers/md/Kconfig
>> index 91a02ee..42249c1 100644
>> --- a/drivers/md/Kconfig
>> +++ b/drivers/md/Kconfig
>> @@ -388,6 +388,19 @@ config DM_VERITY
>>           To compile this code as a module, choose M here: the module will
>>           be called dm-verity.
>>
>> +config DM_INTEGRITY
>> +       tristate "Integrity target support"
>> +       depends on BLK_DEV_DM
>> +       select CRYPTO
>> +       select CRYPTO_HMAC
>> +       select DM_BUFIO
>> +       select KEYS
>> +       ---help---
>> +         If you say Y here, then your ...
>> +
>> +         To compile this as a module, choose M here: the module
>> +         will be called dm-integrity.
>> +
>>           If unsure, say N.
>>
>>  endif # MD
>> diff --git a/drivers/md/Makefile b/drivers/md/Makefile
>> index 94dce8b..49b212f 100644
>> --- a/drivers/md/Makefile
>> +++ b/drivers/md/Makefile
>> @@ -41,6 +41,7 @@ obj-$(CONFIG_DM_PERSISTENT_DATA)      += persistent-data/
>>  obj-$(CONFIG_DM_MIRROR)                += dm-mirror.o dm-log.o dm-region-hash.o
>>  obj-$(CONFIG_DM_LOG_USERSPACE) += dm-log-userspace.o
>>  obj-$(CONFIG_DM_ZERO)          += dm-zero.o
>> +obj-$(CONFIG_DM_INTEGRITY)     += dm-integrity.o
>>  obj-$(CONFIG_DM_RAID)  += dm-raid.o
>>  obj-$(CONFIG_DM_THIN_PROVISIONING)     += dm-thin-pool.o
>>  obj-$(CONFIG_DM_VERITY)                += dm-verity.o
>> diff --git a/drivers/md/dm-integrity.c b/drivers/md/dm-integrity.c
>> new file mode 100644
>> index 0000000..3b3a27e
>> --- /dev/null
>> +++ b/drivers/md/dm-integrity.c
>> @@ -0,0 +1,1050 @@
>> +/*
>> + * dm-integrity - device mapper integrity target
>> + *
>> + * Copyright (C) 2012, Intel Corporation.
>> + *
>> + * Author: Dmitry Kasatkin <dmitry kasatkin intel com>
>> + *
>> + * This program is free software; you can redistribute it and/or modify it
>> + * under the terms and conditions of the GNU General Public License,
>> + * version 2, as published by the Free Software Foundation.
>> + *
>> + * This program is distributed in the hope it will be useful, but WITHOUT
>> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
>> + * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
>> + * more details.
>> + *
>> + * You should have received a copy of the GNU General Public License along with
>> + * this program; if not, write to the Free Software Foundation, Inc.,
>> + * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
>> + *
>> + */
>> +
>> +#define DM_MSG_PREFIX KBUILD_MODNAME
>> +
>> +#define pr_fmt(fmt) KBUILD_MODNAME ": %s: " fmt, __func__
>> +
>> +#include "dm.h"
>> +#include <linux/module.h>
>> +#include <linux/init.h>
>> +#include <linux/blkdev.h>
>> +#include <linux/bio.h>
>> +#include <linux/slab.h>
>> +#include <linux/device-mapper.h>
>> +#include <linux/crypto.h>
>> +#include <linux/scatterlist.h>
>> +#include <crypto/sha.h>
>> +#include <crypto/hash.h>
>> +#include <keys/encrypted-type.h>
>> +#include <linux/wait.h>
>> +#include <linux/reboot.h>
>> +
>> +#include "dm-bufio.h"
>> +
>> +#define DM_INT_STATS
>> +
>> +#define DM_INT_MIN_IOS         16
>> +#define DM_INT_BLOCK_SIZE      PAGE_SIZE
>> +#define DM_INT_MAX_KEY_SIZE    128
>> +
>> +/* best parameters for fastest Ubuntu boot */
>> +#define DM_INT_PREFETCH_COUNT  16
>> +#define DM_INT_FLUSH_DELAY     (HZ * 3)        /* bufio flush delay */
>> +
>> +struct ahash_result {
>> +       struct completion completion;
>> +       int err;
>> +};
>> +
>> +struct dm_int_io {
>> +       struct dm_int *dmi;     /* mapping it belongs to */
>> +       struct bio *bio;
>> +       struct work_struct work;
>> +
>> +#define DM_INT_BIO_DONE                1
>> +#define DM_INT_VERIFIED                2
>> +#define DM_INT_HMAC_DONE       3
>> +       unsigned long flags;
>> +
>> +       atomic_t count;
>> +       int error;
>> +
>> +       sector_t sector;
>> +
>> +       bio_end_io_t *bi_end_io;        /* original bio callback */
>> +       void *bi_private;       /* original bio private data */
>> +       unsigned int bi_size;
>> +
>> +       struct ahash_request req;
>> +};
>> +
>> +/*
>> + * integrity mapping configuration
>> + */
>> +struct dm_int {
>> +       struct dm_target *target;
>> +       struct dm_dev *dev;
>> +       char *table_string;
>> +       loff_t start;
>> +       struct dm_dev *hdev;
>> +       loff_t hmac_start;
>> +       loff_t hmac_count;
>> +
>> +       struct mutex mutex;     /* lock the store */
>> +
>> +       struct workqueue_struct *io_queue;
>> +       struct kmem_cache *io_cache;
>> +       mempool_t *io_pool;
>> +
>> +       struct crypto_ahash *ahash;
>> +       struct crypto_shash *hmac;
>> +
>> +       struct list_head list;  /* global list */
>> +
>> +       struct dm_bufio_client *bufio;
>> +
>> +       unsigned int hmac_size;
>> +       unsigned int data_block_size;
>> +       unsigned int data_block_bits;
>> +       unsigned int hmac_block_size;
>> +       unsigned int hmac_block_bits;
>> +       unsigned int hmac_per_block;
>> +       unsigned int hmac_block_shift;
>> +       unsigned int delay;     /* hmac sync delay */
>> +
>> +#define DM_INT_FLAGS_FIX       0x01    /* fix wrong hmacs */
>> +#ifdef DM_INT_STATS
>> +#define DM_INT_FLAGS_STATS     0x02    /* calc stats */
>> +#else
>> +/* setting to 0 will eliminate the code due to optimization */
>> +#define DM_INT_FLAGS_STATS     0x00
>> +#endif
>> +#define DM_INT_FLAGS_VERBOSE   0x04    /* show failed blocks */
>> +       unsigned int flags;
>> +
>> +       atomic_t count;         /* total reference count */
>> +       wait_queue_head_t wait; /* for close */
>> +       atomic_t violations;
>> +
>> +       /* stats */
>> +#ifdef DM_INT_STATS
>> +       atomic_t io_count;
>> +       int io_count_max;
>> +       atomic_t data_write_count;
>> +       atomic_t data_read_count;
>> +#endif
>> +};
>> +
>> +static DEFINE_MUTEX(mutex);
>> +static LIST_HEAD(dmi_list);
>> +static int sync_mode;
>> +
>> +static void dm_int_queue_hmac(struct dm_int_io *io);
>> +
>> +/*
>> + * Get the key from the TPM for the HMAC
>> + */
>> +static int dm_int_init_crypto(struct dm_int *dmi, const char *hash_algo,
>> +                             const char *hmac_algo, const char *keyname)
>> +{
>> +       struct key *key;
>> +       struct encrypted_key_payload *ekp;
>> +       int err = -EINVAL;
>> +
>> +       dmi->ahash = crypto_alloc_ahash(hash_algo, 0, 0);
>> +       if (IS_ERR(dmi->ahash)) {
>> +               err = PTR_ERR(xchg(&dmi->ahash, NULL));
>> +               DMERR("failed to load %s algorithm: %d\n", hash_algo, err);
>> +               dmi->target->error = "Cannot allocate hash algorithm";
>> +               return err;
>> +       }
>> +
>> +       dmi->hmac = crypto_alloc_shash(hmac_algo, 0, 0);
>> +       if (IS_ERR(dmi->hmac)) {
>> +               err = PTR_ERR(xchg(&dmi->hmac, NULL));
>> +               DMERR("failed to load %s algorithm: %d\n", hmac_algo, err);
>> +               dmi->target->error = "Cannot allocate hash algorithm";
>> +               return err;
>> +       }
>> +
>> +       key = request_key(&key_type_encrypted, keyname, NULL);
>> +       if (IS_ERR(key)) {
>> +               dmi->target->error = "Invalid key name";
>> +               return -ENOENT;
>> +       }
>> +
>> +       down_read(&key->sem);
>> +       ekp = key->payload.data;
>> +       if (ekp->decrypted_datalen <= DM_INT_MAX_KEY_SIZE)
>> +               err = crypto_shash_setkey(dmi->hmac, ekp->decrypted_data,
>> +                                         ekp->decrypted_datalen);
>> +
>> +       /* burn the original key contents */
>> +       /*memset(ekp->decrypted_data, 0, ekp->decrypted_datalen); */
>> +       up_read(&key->sem);
>> +       key_put(key);
>> +
>> +       return err;
>> +}
>> +
>> +static void dm_int_io_get(struct dm_int_io *io)
>> +{
>> +       struct dm_int *dmi = io->dmi;
>> +
>> +       atomic_inc(&io->count);
>> +       atomic_inc(&dmi->count);
>> +
>> +       pr_debug("entered: io: %p, pending %d/%d\n",
>> +                io, atomic_read(&io->count), atomic_read(&dmi->count));
>> +}
>> +
>> +static void dm_int_io_put(struct dm_int_io *io)
>> +{
>> +       struct dm_int *dmi = io->dmi;
>> +       struct bio *bio = io->bio;
>> +       int err = io->error;
>> +
>> +       pr_debug("entered: io: %p, pending %d/%d\n",
>> +                io, atomic_read(&io->count), atomic_read(&dmi->count));
>> +
>> +       atomic_dec(&dmi->count);
>> +
>> +       if (!atomic_dec_and_test(&io->count))
>> +               return;
>> +
>> +       /* request has completed */
>> +       if (!err && test_bit(DM_INT_BIO_DONE, &io->flags) &&
>> +           !test_bit(DM_INT_VERIFIED, &io->flags)) {
>> +               /* io->count will be 1 */
>> +               pr_debug("queue to verify: %p\n", io);
>> +               dm_int_queue_hmac(io);
>> +               return;
>> +       }
>> +
>> +       pr_debug("io done: err: %d, io: %d/%d\n",
>> +                err, atomic_read(&io->count), atomic_read(&dmi->count));
>> +
>> +       mempool_free(io, dmi->io_pool);
>> +
>> +       bio_endio(bio, err);    /* finally completed, end main bio */
>> +
>> +       if (dmi->flags & DM_INT_FLAGS_STATS)
>> +               atomic_dec(&dmi->io_count);
>> +
>> +       if (err)
>> +               DMERR("ERROR: io done: %d\n", err);
>> +
>> +       wake_up_all(&dmi->wait);
>> +}
>> +
>> +static void dm_int_prefetch(struct dm_int_io *io)
>> +{
>> +       struct dm_int *dmi = io->dmi;
>> +       loff_t first, last, data;
>> +       loff_t offset;
>> +
>> +       /* block number to read */
>> +       offset = io->sector << SECTOR_SHIFT;
>> +       data = offset >> dmi->data_block_bits;
>> +       if (dmi->hmac_block_shift)
>> +               first = data >> dmi->hmac_block_shift;
>> +       else {
>> +               first = data;
>> +               sector_div(first, dmi->hmac_per_block);
>> +       }
>> +
>> +       /* offset to the last byte of data */
>> +       offset += (io->bi_size - 1);
>> +       data = offset >> dmi->data_block_bits;
>> +       if (dmi->hmac_block_shift)
>> +               last = data >> dmi->hmac_block_shift;
>> +       else  {
>> +               last = data;
>> +               sector_div(last, dmi->hmac_per_block);
>> +       }
>> +
>> +       /* prefetch multiple of DM_INT_PREFETCH_COUNT */
>> +       first = round_down(first, DM_INT_PREFETCH_COUNT);
>> +       last = round_up(last + 1, DM_INT_PREFETCH_COUNT);
>> +       /* check the end of the device */
>> +       if (last > dmi->hmac_count)
>> +               last = dmi->hmac_count;
>> +
>> +       dm_bufio_prefetch(dmi->bufio, dmi->hmac_start + first, last - first);
>> +}
>> +
>> +static int dm_int_verify_hmac(struct dm_int_io *io, loff_t offset,
>> +                             u8 *collected, int update)
>> +{
>> +       struct dm_int *dmi = io->dmi;
>> +       loff_t block, data = offset >> dmi->data_block_bits;
>> +       unsigned int index;
>> +       u8 *digest;
>> +       int err = 0;
>> +       struct dm_buffer *buf;
>> +
>> +       if (dmi->hmac_block_shift) {
>> +               block = data >> dmi->hmac_block_shift;
>> +               index = data & ((1 << dmi->hmac_block_shift) - 1);
>> +       } else {
>> +               block = data;
>> +               index = sector_div(block, dmi->hmac_per_block);
>> +       }
>> +
>> +       pr_debug("hmac: block: %llu, index: %u\n", block, index);
>> +
>> +       digest = dm_bufio_read(dmi->bufio, dmi->hmac_start + block, &buf);
>> +       if (unlikely(IS_ERR(digest)))
>> +               return PTR_ERR(digest);
>> +
>> +       digest += dmi->hmac_size * index;
>> +
>> +       if (!update) {
>> +               err = memcmp(digest, collected, dmi->hmac_size);
>> +               if (err) {
>> +                       err = -EIO;
>> +                       /* update buffer and store it back */
>> +                       atomic_inc(&dmi->violations);
>> +                       if (dmi->flags & DM_INT_FLAGS_FIX) {
>> +                               err = 0;
>> +                               update = 1;
>> +                       }
>> +                       if (dmi->flags & DM_INT_FLAGS_VERBOSE) {
>> +                               DMERR("ERROR: hmacs does not match\n");
>> +                               DMERR("hmac: block: %llu, index: %u\n",
>> +                                     block, index);
>> +                               print_hex_dump(KERN_CRIT, "collected: ",
>> +                                              0, 32, 1, collected, 20, 0);
>> +                               print_hex_dump(KERN_CRIT, "hmac: ",
>> +                                              0, 32, 1, digest, 20, 0);
>> +                       }
>> +               }
>> +       }
>> +
>> +       if (update) {
>> +               memcpy(digest, collected, dmi->hmac_size);
>> +               dm_bufio_mark_buffer_dirty(buf);
>> +       }
>> +
>> +       dm_bufio_release(buf);
>> +
>> +       if (err)
>> +               DMERR_LIMIT("ERROR: HMACs do not match\n");
>> +
>> +       return err;
>> +}
>> +
>> +static void dm_int_ahash_complete(struct crypto_async_request *req, int err)
>> +{
>> +       struct ahash_result *res = req->data;
>> +
>> +       if (err == -EINPROGRESS)
>> +               return;
>> +       res->err = err;
>> +       complete(&res->completion);
>> +}
>> +
>> +static int dm_int_ahash_wait(int err, struct ahash_result *res)
>> +{
>> +       switch (err) {
>> +       case 0:
>> +               break;
>> +       case -EINPROGRESS:
>> +       case -EBUSY:
>> +               wait_for_completion(&res->completion);
>> +               err = res->err;
>> +               if (!res->err) {
>> +                       INIT_COMPLETION(res->completion);
>> +                       break;
>> +               }
>> +               /* fall through */
>> +       default:
>> +               DMERR("HMAC calculation failed: err: %d\n", err);
>> +       }
>> +
>> +       return err;
>> +}
>> +
>> +static int dm_int_calc_hmac(struct dm_int_io *io, loff_t offset,
>> +                           u8 *digest, unsigned int size, u8 *hmac)
>> +{
>> +       struct dm_int *dmi = io->dmi;
>> +       int err;
>> +       struct {
>> +               struct shash_desc shash;
>> +               char ctx[crypto_shash_descsize(dmi->hmac)];
>> +       } desc;
>> +
>> +       desc.shash.tfm = dmi->hmac;
>> +       desc.shash.flags = CRYPTO_TFM_REQ_MAY_SLEEP;
>> +
>> +       err = crypto_shash_init(&desc.shash);
>> +       if (!err)
>> +               err = crypto_shash_update(&desc.shash, digest, size);
>> +       if (!err)
>> +               err = crypto_shash_finup(&desc.shash, (u8 *)&offset,
>> +                                         sizeof(offset), hmac);
>> +       if (err)
>> +               DMERR("ERROR: calc hmac failed: %d\n", err);
>> +       return err;
>> +}
>> +
>> +static void dm_int_verify_io(struct dm_int_io *io)
>> +{
>> +       struct dm_int *dmi = io->dmi;
>> +       struct bio *bio = io->bio;
>> +       struct bio_vec *bv;
>> +       int i, err = -EIO;
>> +       struct scatterlist sg[1];
>> +       u8 hmac[dmi->hmac_size];
>> +       u8 digest[crypto_ahash_digestsize(dmi->ahash)];
>> +       loff_t offset = io->sector << SECTOR_SHIFT;
>> +       unsigned int update = bio_data_dir(bio);
>> +       struct ahash_request *req = &io->req;
>> +       struct ahash_result res;
>> +       ssize_t size = io->bi_size;
>> +
>> +       init_completion(&res.completion);
>> +       ahash_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
>> +                                  CRYPTO_TFM_REQ_MAY_SLEEP,
>> +                                  dm_int_ahash_complete, &res);
>> +
>> +       sg_init_table(sg, 1);
>> +
>> +       pr_debug("io: %p, sector: %llu, size: %d, vcnt: %d, idx: %d\n",
>> +                io, (loff_t)io->sector,
>> +                bio->bi_size, bio->bi_vcnt, bio->bi_idx);
>> +
>> +       bio_for_each_segment(bv, bio, i) {
>> +               pr_debug("bv: %d: offset: %llu, bv_offset: %d, bv_len: %d\n",
>> +                        i, offset, bv->bv_offset, bv->bv_len);
>> +
>> +               BUG_ON(bv->bv_offset & (dmi->data_block_size - 1));
>> +               BUG_ON(bv->bv_len & (dmi->data_block_size - 1));
>> +
>> +               sg_set_page(sg, bv->bv_page, bv->bv_len, bv->bv_offset);
>> +
>> +               ahash_request_set_crypt(req, sg, digest, bv->bv_len);
>> +
>> +               err = crypto_ahash_digest(req);
>> +               err = dm_int_ahash_wait(err, req->base.data);
>> +               if (err)
>> +                       break;
>> +
>> +               err = dm_int_calc_hmac(io, offset, digest, sizeof(digest),
>> +                                      hmac);
>> +               if (err)
>> +                       break;
>> +
>> +               err = dm_int_verify_hmac(io, offset, hmac, update);
>> +               if (err)
>> +                       break;
>> +
>> +               offset += bv->bv_len;
>> +               size -= bv->bv_len;
>> +       }
>> +
>> +       if (size)
>> +               DMERR("ERROR: size is not zero: %zd\n", size);
>> +
>> +       io->error = err;
>> +       set_bit(DM_INT_VERIFIED, &io->flags);
>> +
>> +       if (sync_mode)
>> +               dm_bufio_write_dirty_buffers(dmi->bufio);
>> +}
>> +
>> +static void dm_int_hmac_task(struct work_struct *work)
>> +{
>> +       struct dm_int_io *io = container_of(work, struct dm_int_io, work);
>> +
>> +       if (test_and_set_bit(DM_INT_HMAC_DONE, &io->flags))
>> +               dm_int_verify_io(io);
>> +       else
>> +               dm_int_prefetch(io);
>> +
>> +       dm_int_io_put(io);
>> +}
>> +
>> +static void dm_int_queue_hmac(struct dm_int_io *io)
>> +{
>> +       struct dm_int *dmi = io->dmi;
>> +       int ret;
>> +
>> +       /* what if it is queued already? */
>> +       dm_int_io_get(io);
>> +       ret = queue_work(dmi->io_queue, &io->work);
>> +       if (!ret)
>> +               dm_int_io_put(io);
>> +       BUG_ON(!ret);
>> +}
>> +
>> +static void dm_int_end_io(struct bio *bio, int err)
>> +{
>> +       struct dm_int_io *io = bio->bi_private;
>> +       struct dm_int *dmi = io->dmi;
>> +
>> +       pr_debug("io: %p, pending: %d/%d, sector: %llu, size: %u, "\
>> +                "vcnt: %d, idx: %d\n", io,
>> +                atomic_read(&io->count), atomic_read(&dmi->count),
>> +                (loff_t)bio->bi_sector,
>> +                bio->bi_size, bio->bi_vcnt, bio->bi_idx);
>> +
>> +       if (unlikely(!bio_flagged(bio, BIO_UPTODATE) && !err))
>> +               err = -EIO;
>> +
>> +       if (err)
>> +               DMERR("ERROR: bio io failed: %d\n", err);
>> +
>> +       if (unlikely(err))
>> +               io->error = err;
>> +
>> +       set_bit(DM_INT_BIO_DONE, &io->flags);
>> +
>> +       bio->bi_private = io->bi_private;
>> +       bio->bi_end_io = io->bi_end_io;
>> +
>> +       dm_int_io_put(io);
>> +}
>> +
>> +static void dm_int_start_io(struct dm_int_io *io)
>> +{
>> +       struct dm_int *dmi = io->dmi;
>> +       struct bio *bio = io->bio;
>> +
>> +       if (io->error)
>> +               return;
>> +
>> +       io->bi_private = bio->bi_private;
>> +       io->bi_end_io = bio->bi_end_io;
>> +
>> +       /* io->sector starts from 0 */
>> +       bio->bi_sector = dmi->start + io->sector;
>> +       bio->bi_bdev = dmi->dev->bdev;
>> +
>> +       bio->bi_private = io;
>> +       bio->bi_end_io = dm_int_end_io;
>> +
>> +       dm_int_io_get(io);
>> +
>> +       if (dmi->flags & DM_INT_FLAGS_STATS) {
>> +               if (bio_data_dir(bio) == READ)
>> +                       atomic_inc(&dmi->data_read_count);
>> +               else
>> +                       atomic_inc(&dmi->data_write_count);
>> +       }
>> +
>> +       generic_make_request(bio);
>> +}
>> +
>> +static struct dm_int_io *dm_int_io_alloc(struct dm_int *dmi,
>> +                                        struct bio *bio, sector_t sector)
>> +{
>> +       struct dm_int_io *io;
>> +
>> +       /* never fails with GFP_NOIO */
>> +       io = mempool_alloc(dmi->io_pool, GFP_NOIO);
>> +       BUG_ON(!io);
>> +
>> +       io->dmi = dmi;
>> +       io->bio = bio;
>> +       io->bi_size = bio->bi_size;
>> +       io->sector = sector;
>> +       io->error = 0;
>> +       io->flags = 0;
>> +
>> +       INIT_WORK(&io->work, dm_int_hmac_task);
>> +
>> +       ahash_request_set_tfm(&io->req, dmi->ahash);
>> +
>> +       atomic_set(&io->count, 1);
>> +       atomic_inc(&dmi->count);
>> +
>> +       /* stats */
>> +       if (dmi->flags & DM_INT_FLAGS_STATS) {
>> +               atomic_inc(&dmi->io_count);
>> +               if (atomic_read(&dmi->io_count) > dmi->io_count_max)
>> +                       dmi->io_count_max = atomic_read(&dmi->io_count);
>> +       }
>> +
>> +       return io;
>> +}
>> +
>> +static int dm_int_map(struct dm_target *ti, struct bio *bio,
>> +                     union map_info *map_context)
>> +{
>> +       struct dm_int *dmi = ti->private;
>> +       struct dm_int_io *io;
>> +
>> +       /*
>> +        * If bio is REQ_FLUSH or REQ_DISCARD, just bypass crypt queues.
>> +        * - for REQ_FLUSH device-mapper core ensures that no IO is in-flight
>> +        * - for REQ_DISCARD caller must use flush if IO ordering matters
>> +        */
>> +       if (unlikely(bio->bi_rw & (REQ_FLUSH | REQ_DISCARD))) {
>> +               bio->bi_bdev = dmi->dev->bdev;
>> +               bio->bi_sector =
>> +                       dmi->start + dm_target_offset(ti, bio->bi_sector);
>> +               return DM_MAPIO_REMAPPED;
>> +       }
>> +
>> +       /* a check to see if something unhandled might come */
>> +       if (!bio->bi_size || !bio->bi_vcnt)
>> +               DMERR("bio without data: size: %d, vcnt: %d\n",
>> +                     bio->bi_size, bio->bi_vcnt);
>> +
>> +       BUG_ON(bio->bi_sector & (to_sector(dmi->data_block_size) - 1));
>> +       BUG_ON(bio->bi_size & (dmi->data_block_size - 1));
>> +
>> +       io = dm_int_io_alloc(dmi, bio, dm_target_offset(ti, bio->bi_sector));
>> +
>> +       pr_debug("io: %p, sector: %llu, size: %u, vcnt: %d, idx: %d\n",
>> +                io, (loff_t)bio->bi_sector,
>> +                bio->bi_size, bio->bi_vcnt, bio->bi_idx);
>> +
>> +       dm_int_start_io(io);
>> +       dm_int_queue_hmac(io);
>> +
>> +       dm_int_io_put(io);
>> +
>> +       return DM_MAPIO_SUBMITTED;
>> +}
>> +
>> +static void dm_int_cleanup(struct dm_target *ti)
>> +{
>> +       struct dm_int *dmi = (struct dm_int *)ti->private;
>> +
>> +       if (dmi->bufio)
>> +               dm_bufio_client_destroy(dmi->bufio);
>> +       if (dmi->io_queue)
>> +               destroy_workqueue(dmi->io_queue);
>> +       if (dmi->io_pool)
>> +               mempool_destroy(dmi->io_pool);
>> +       if (dmi->io_cache)
>> +               kmem_cache_destroy(dmi->io_cache);
>> +       if (dmi->ahash)
>> +               crypto_free_ahash(dmi->ahash);
>> +       if (dmi->hmac)
>> +               crypto_free_shash(dmi->hmac);
>> +       if (dmi->hdev)
>> +               dm_put_device(ti, dmi->hdev);
>> +       if (dmi->dev)
>> +               dm_put_device(ti, dmi->dev);
>> +       kfree(dmi->table_string);
>> +       kfree(dmi);
>> +}
>> +
>> +/*
>> + * Construct an integrity mapping:
>> + * <dev> <bs> <start> <hdev> <hbs> <hstart> <hash_algo> <hmac_algo> <keyname> \
>> + * [opt_params]
>> + */
>> +static int dm_int_ctr(struct dm_target *ti, unsigned int argc, char **argv)
>> +{
>> +       struct dm_int *dmi;
>> +       int err, io_size, i, count;
>> +       unsigned long long tmpll;
>> +       char table[256], dummy;
>> +       unsigned tmp;
>> +       fmode_t mode;
>> +       loff_t datadevsize, hmacdevsize, maxdatasize, maxhmacsize;
>> +
>> +       if (argc < 9) {
>> +               ti->error = "Invalid argument count";
>> +               return -EINVAL;
>> +       }
>> +
>> +       dmi = kzalloc(sizeof(*dmi), GFP_KERNEL);
>> +       if (dmi == NULL) {
>> +               ti->error = "dm-integrity: Cannot allocate linear context";
>> +               return -ENOMEM;
>> +       }
>> +
>> +       dmi->target = ti;
>> +       ti->private = dmi;
>> +
>> +       err = -EINVAL;
>> +
>> +       mode = dm_table_get_mode(ti->table);
>> +
>> +       if (dm_get_device(ti, argv[0], mode, &dmi->dev)) {
>> +               ti->error = "Device lookup failed";
>> +               goto err;
>> +       }
>> +
>> +       if (sscanf(argv[1], "%u%c", &tmp, &dummy) != 1 ||
>> +          !is_power_of_2(tmp) ||
>> +          tmp < bdev_logical_block_size(dmi->dev->bdev) ||
>> +          tmp > PAGE_SIZE) {
>> +               ti->error = "Invalid device block size";
>> +               goto err;
>> +       }
>> +       dmi->data_block_size = tmp;
>> +       dmi->data_block_bits = ffs(dmi->data_block_size) - 1;
>> +
>> +       if (sscanf(argv[2], "%llu%c", &tmpll, &dummy) != 1) {
>> +               ti->error = "Invalid device start";
>> +               goto err;
>> +       }
>> +       dmi->start = tmpll;
>> +
>> +       if (dm_get_device(ti, argv[3], mode, &dmi->hdev)) {
>> +               ti->error = "HMAC device lookup failed";
>> +               goto err;
>> +       }
>> +
>> +       if (sscanf(argv[4], "%u%c", &tmp, &dummy) != 1 ||
>> +          !is_power_of_2(tmp) ||
>> +          tmp < bdev_logical_block_size(dmi->dev->bdev) ||
>> +          tmp > PAGE_SIZE) {
>> +               ti->error = "Invalid device block size";
>> +               goto err;
>> +       }
>> +       dmi->hmac_block_size = tmp;
>> +       dmi->hmac_block_bits = ffs(dmi->hmac_block_size) - 1;
>> +
>> +       if (sscanf(argv[5], "%llu%c", &tmpll, &dummy) != 1) {
>> +               ti->error = "Invalid hmac device start";
>> +               goto err;
>> +       }
>> +       dmi->hmac_start = tmpll;
>> +
>> +       err = dm_int_init_crypto(dmi, argv[6], argv[7], argv[8]);
>> +       if (err)
>> +               goto err;
>> +
>> +       count = snprintf(table, sizeof(table), "%s %u %llu %s %u %llu %s %s %s",
>> +                        dmi->dev->name, dmi->data_block_size, dmi->start,
>> +                        dmi->hdev->name, dmi->hmac_block_size, dmi->hmac_start,
>> +                        argv[6], argv[7], argv[8]);
>> +
>> +       for (i = 9; i < argc; i++) {
>> +               count += snprintf(table + count, sizeof(table) - count,
>> +                                 " %s", argv[i]);
>> +       }
>> +
>> +       dmi->table_string = kstrdup(table, GFP_KERNEL);
>> +
>> +       dmi->hmac_size = crypto_shash_digestsize(dmi->hmac);
>> +
>> +       /* how many hmacs do we need for data device */
>> +       dmi->hmac_count = ti->len >> (dmi->data_block_bits - SECTOR_SHIFT);
>> +
>> +       datadevsize = i_size_read(dmi->dev->bdev->bd_inode) >> SECTOR_SHIFT;
>> +       hmacdevsize = i_size_read(dmi->hdev->bdev->bd_inode) >> SECTOR_SHIFT;
>> +
>> +       err = -EINVAL;
>> +
>> +       if (dmi->start > datadevsize) {
>> +               DMERR("start sector is beyond device size: %llu (%llu)\n",
>> +                     dmi->start, datadevsize);
>> +               goto err;
>> +       }
>> +
>> +       if (dmi->hmac_start > hmacdevsize) {
>> +               DMERR("start sector is beyond device size: %llu (%llu)\n",
>> +                     dmi->hmac_start, hmacdevsize);
>> +               goto err;
>> +       }
>> +
>> +       if (dmi->dev->bdev == dmi->hdev->bdev) {
>> +               if (dmi->hmac_start > dmi->start) {
>> +                       maxdatasize = dmi->hmac_start - dmi->start;
>> +                       maxhmacsize = datadevsize - dmi->hmac_start;
>> +               } else {
>> +                       maxhmacsize = dmi->start - dmi->hmac_start;
>> +                       maxdatasize = datadevsize - dmi->start;
>> +               }
>> +       } else {
>> +               maxdatasize = datadevsize - dmi->start;
>> +               maxhmacsize = hmacdevsize - dmi->hmac_start;
>> +       }
>> +
>> +       if (ti->len > maxdatasize) {
>> +               DMERR("target size is too big: %llu (%llu)\n",
>> +                     (loff_t)ti->len, maxdatasize);
>> +               goto err;
>> +       }
>> +
>> +       /* hmac start in blocks */
>> +       dmi->hmac_start >>= (dmi->hmac_block_bits - SECTOR_SHIFT);
>> +
>> +       /* optimize for SHA256  which is 32 bytes */
>> +       if (is_power_of_2(dmi->hmac_size)) {
>> +               dmi->hmac_block_shift =
>> +                       dmi->hmac_block_bits - (ffs(dmi->hmac_size) - 1);
>> +               /* how many hmac blocks do we need */
>> +               dmi->hmac_count >>= dmi->hmac_block_shift;
>> +       } else {
>> +               dmi->hmac_per_block = dmi->hmac_block_size / dmi->hmac_size;
>> +               /* how many hmac blocks do we need */
>> +               tmpll = sector_div(dmi->hmac_count, dmi->hmac_per_block);
>> +               if (tmpll)
>> +                       dmi->hmac_count++;
>> +       }
>> +
>> +       /* device may hold as many hmac blocks */
>> +       maxhmacsize >>= (dmi->hmac_block_bits - SECTOR_SHIFT);
>> +
>> +       if (dmi->hmac_count > maxhmacsize) {
>> +               DMERR("HMAC device is too small: %llu (%llu)\n",
>> +                     dmi->hmac_count, maxhmacsize);
>> +               goto err;
>> +       }
>> +
>> +       ti->num_discard_requests = 1;
>> +
>> +       for (i = 9; i < argc; i++) {
>> +               if (!strcmp(argv[i], "fix"))
>> +                       dmi->flags |= DM_INT_FLAGS_FIX;
>> +               else if (!strcmp(argv[i], "stats"))
>> +                       dmi->flags |= DM_INT_FLAGS_STATS;
>> +               else if (!strcmp(argv[i], "verbose"))
>> +                       dmi->flags |= DM_INT_FLAGS_VERBOSE;
>> +               else if (!strcmp(argv[i], "disallow_discards"))
>> +                       ti->num_discard_requests = 0;
>> +       }
>> +
>> +       err = -ENOMEM;
>> +
>> +       io_size = sizeof(struct dm_int_io);
>> +       io_size += crypto_ahash_reqsize(dmi->ahash);
>> +       dmi->io_cache = kmem_cache_create("dm_int_io_cache", io_size,
>> +                                         __alignof__(struct dm_int_io), 0,
>> +                                         NULL);
>> +       if (!dmi->io_cache) {
>> +               ti->error = "Cannot allocate dm_int io cache";
>> +               goto err;
>> +       }
>> +
>> +       dmi->io_pool = mempool_create_slab_pool(DM_INT_MIN_IOS, dmi->io_cache);
>> +       if (!dmi->io_pool) {
>> +               ti->error = "Cannot allocate dm_int io mempool";
>> +               goto err;
>> +       }
>> +
>> +       dmi->io_queue = alloc_workqueue("dm_int_hmac",
>> +                                         WQ_CPU_INTENSIVE |
>> +                                         WQ_HIGHPRI |
>> +                                         WQ_UNBOUND |
>> +                                         WQ_MEM_RECLAIM,
>> +                                         1);
>> +       if (!dmi->io_queue) {
>> +               ti->error = "Couldn't create dm_int hmac queue";
>> +               goto err;
>> +       }
>> +
>> +       dmi->bufio = dm_bufio_client_create(dmi->hdev->bdev,
>> +                                           dmi->hmac_block_size, 1, 0,
>> +                                           NULL, NULL);
>> +       if (IS_ERR(dmi->bufio)) {
>> +               ti->error = "Cannot initialize dm-bufio";
>> +               err = PTR_ERR(xchg(&dmi->bufio, NULL));
>> +               goto err;
>> +       }
>> +
>> +       mutex_init(&dmi->mutex);
>> +       dmi->delay = DM_INT_FLUSH_DELAY;
>> +       init_waitqueue_head(&dmi->wait);
>> +
>> +       ti->num_flush_requests = 1;
>> +       /* it should depend on read block device... */
>> +       /*ti->discard_zeroes_data_unsupported = true;*/
>> +
>> +       mutex_lock(&mutex);
>> +       list_add(&dmi->list, &dmi_list);
>> +       mutex_unlock(&mutex);
>> +
>> +       return 0;
>> +
>> +err:
>> +       dm_int_cleanup(ti);
>> +       return err;
>> +}
>> +
>> +static void dm_int_dtr(struct dm_target *ti)
>> +{
>> +       struct dm_int *dmi = (struct dm_int *)ti->private;
>> +
>> +       mutex_lock(&mutex);
>> +       list_del(&dmi->list);
>> +       mutex_unlock(&mutex);
>> +
>> +       dm_int_cleanup(ti);
>> +}
>> +
>> +static void dm_int_sync(struct dm_int *dmi)
>> +{
>> +       /* first flush hmac queue, which might schedule idata delayed work */
>> +       flush_workqueue(dmi->io_queue);
>> +       /* write all updated hmac blocks */
>> +       dm_bufio_write_dirty_buffers(dmi->bufio);
>> +
>> +       if (atomic_read(&dmi->count))
>> +               DMWARN("dmi->count: %d\n", atomic_read(&dmi->count));
>> +       /* wait until all idata bios complete */
>> +       wait_event(dmi->wait, !atomic_read(&dmi->count));
>> +}
>> +
>> +static int dm_int_ioctl(struct dm_target *ti, unsigned int cmd,
>> +                       unsigned long arg)
>> +{
>> +       struct dm_int *dmi = (struct dm_int *)ti->private;
>> +       struct dm_dev *dev = dmi->dev;
>> +       int err = 0;
>> +
>> +       if (cmd == BLKFLSBUF)
>> +               dm_int_sync(dmi);
>> +
>> +       /*
>> +        * Only pass ioctls through if the device sizes match exactly.
>> +        */
>> +       if (dmi->start ||
>> +           ti->len != i_size_read(dev->bdev->bd_inode) >> SECTOR_SHIFT)
>> +               err = scsi_verify_blk_ioctl(NULL, cmd);
>> +
>> +       return err ? : __blkdev_driver_ioctl(dev->bdev, dev->mode, cmd, arg);
>> +}
>> +
>> +static int dm_int_merge(struct dm_target *ti, struct bvec_merge_data *bvm,
>> +                       struct bio_vec *biovec, int max_size)
>> +{
>> +       struct dm_int *dmi = ti->private;
>> +       struct request_queue *q = bdev_get_queue(dmi->dev->bdev);
>> +
>> +       if (!q->merge_bvec_fn)
>> +               return max_size;
>> +
>> +       bvm->bi_bdev = dmi->dev->bdev;
>> +       bvm->bi_sector = dmi->start + dm_target_offset(ti, bvm->bi_sector);
>> +
>> +       return min(max_size, q->merge_bvec_fn(q, bvm, biovec));
>> +}
>> +
>> +static int dm_int_iterate_devices(struct dm_target *ti,
>> +                                 iterate_devices_callout_fn fn, void *data)
>> +{
>> +       struct dm_int *dmi = ti->private;
>> +
>> +       return fn(ti, dmi->dev, dmi->start, ti->len, data);
>> +}
>> +
>> +static void dm_int_io_hints(struct dm_target *ti, struct queue_limits *limits)
>> +{
>> +       struct dm_int *dmi = ti->private;
>> +
>> +       limits->logical_block_size = dmi->data_block_size;
>> +       limits->physical_block_size = dmi->data_block_size;
>> +       blk_limits_io_min(limits, dmi->data_block_size);
>> +}
>> +
>> +static void dm_int_postsuspend(struct dm_target *ti)
>> +{
>> +       struct dm_int *dmi = ti->private;
>> +
>> +       dm_int_sync(dmi);
>> +
>> +       DMINFO("%s suspended\n", dm_device_name(dm_table_get_md(ti->table)));
>> +}
>> +
>> +static int dm_int_status(struct dm_target *ti, status_type_t type,
>> +                        unsigned status_flags, char *result, unsigned maxlen)
>> +{
>> +       struct dm_int *dmi = (struct dm_int *)ti->private;
>> +       unsigned int sz = 0;
>> +
>> +       switch (type) {
>> +       case STATUSTYPE_INFO:
>> +#ifdef DM_INT_STATS
>> +               DMEMIT("pending: %d, io: %d (%d), "\
>> +                      "read: %d, write: %d, "\
>> +                      "violations: %d",
>> +                      atomic_read(&dmi->count),
>> +                      atomic_read(&dmi->io_count), dmi->io_count_max,
>> +                      atomic_read(&dmi->data_read_count),
>> +                      atomic_read(&dmi->data_write_count),
>> +                      atomic_read(&dmi->violations));
>> +#else
>> +               DMEMIT("pending: %d, violations: %d",
>> +                      atomic_read(&dmi->count),
>> +                      atomic_read(&dmi->violations));
>> +#endif
>> +               break;
>> +
>> +       case STATUSTYPE_TABLE:
>> +               DMEMIT("%s", dmi->table_string);
>> +               break;
>> +       }
>> +       return 0;
>> +}
>> +
>> +static struct target_type dm_int_target = {
>> +       .name = "integrity",
>> +       .version = {0, 1, 0},
>> +       .module = THIS_MODULE,
>> +       .ctr = dm_int_ctr,
>> +       .dtr = dm_int_dtr,
>> +       .map = dm_int_map,
>> +       .status = dm_int_status,
>> +       .ioctl = dm_int_ioctl,
>> +       .postsuspend = dm_int_postsuspend,
>> +       .merge = dm_int_merge,
>> +       .iterate_devices = dm_int_iterate_devices,
>> +       .io_hints = dm_int_io_hints,
>> +};
>> +
>> +static int dm_int_notify_reboot(struct notifier_block *this,
>> +                               unsigned long code, void *x)
>> +{
>> +       struct dm_int *dmi;
>> +
>> +       if ((code == SYS_DOWN) || (code == SYS_HALT) ||
>> +                                               (code == SYS_POWER_OFF)) {
>> +               sync_mode = 1;
>> +               mutex_lock(&mutex);
>> +               if (!list_empty(&dmi_list)) {
>> +                       DMINFO("syncing targets...");
>> +                       list_for_each_entry(dmi, &dmi_list, list)
>> +                               dm_int_sync(dmi);
>> +                       pr_cont(" done.\n");
>> +               }
>> +               mutex_unlock(&mutex);
>> +       }
>> +       return NOTIFY_DONE;
>> +}
>> +
>> +static struct notifier_block dm_int_notifier = {
>> +       .notifier_call  = dm_int_notify_reboot,
>> +       .next           = NULL,
>> +       .priority       = INT_MAX, /* before any real devices */
>> +};
>> +
>> +int __init dm_int_init(void)
>> +{
>> +       int err = -ENOMEM;
>> +
>> +       err = dm_register_target(&dm_int_target);
>> +       if (err < 0) {
>> +               DMERR("register failed %d", err);
>> +               return err;
>> +       }
>> +
>> +       /* always returns 0 */
>> +       register_reboot_notifier(&dm_int_notifier);
>> +
>> +       return 0;
>> +}
>> +
>> +void dm_int_exit(void)
>> +{
>> +       unregister_reboot_notifier(&dm_int_notifier);
>> +       dm_unregister_target(&dm_int_target);
>> +}
>> +
>> +/* Module hooks */
>> +module_init(dm_int_init);
>> +module_exit(dm_int_exit);
>> +
>> +MODULE_DESCRIPTION(DM_NAME " integrity target");
>> +MODULE_AUTHOR("Dmitry Kasatkin");
>> +MODULE_LICENSE("GPL");
>> --
>> 1.7.10.4
>>


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