/*
 * Copyright (C) 2003 Jana Saout <jana@saout.de>
 * Copyright (C) 2004 Clemens Fruhwirth <clemens@endorphin.org>
 * Copyright (C) 2006-2017 Red Hat, Inc. All rights reserved.
 * Copyright (C) 2013-2017 Milan Broz <gmazyland@gmail.com>
 *
 * This file is released under the GPL.
 */

#include <linux/completion.h>
#include <linux/err.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/key.h>
#include <linux/bio.h>
#include <linux/blkdev.h>
#include <linux/mempool.h>
#include <linux/slab.h>
#include <linux/crypto.h>
#include <linux/workqueue.h>
#include <linux/kthread.h>
#include <linux/backing-dev.h>
#include <linux/atomic.h>
#include <linux/scatterlist.h>
#include <linux/rbtree.h>
#include <linux/ctype.h>
#include <asm/page.h>
#include <asm/unaligned.h>
#include <crypto/hash.h>
#include <crypto/md5.h>
#include <crypto/algapi.h>
#include <crypto/skcipher.h>
#include <crypto/aead.h>
#include <crypto/authenc.h>
#include <linux/rtnetlink.h> /* for struct rtattr and RTA macros only */
#include <keys/user-type.h>

#include <linux/device-mapper.h>

#define DM_MSG_PREFIX "crypt"

/*
 * context holding the current state of a multi-part conversion
 */
struct convert_context {
        struct completion restart;
        struct bio *bio_in;
        struct bio *bio_out;
        struct bvec_iter iter_in;
        struct bvec_iter iter_out;
        u64 cc_sector;
        atomic_t cc_pending;
        union {
                struct skcipher_request *req;
                struct aead_request *req_aead;
        } r;

};

/*
 * per bio private data
 */
struct dm_crypt_io {
        struct crypt_config *cc;
        struct bio *base_bio;
        u8 *integrity_metadata;
        bool integrity_metadata_from_pool;
        struct work_struct work;

        struct convert_context ctx;

        atomic_t io_pending;
        blk_status_t error;
        sector_t sector;

        struct rb_node rb_node;
} CRYPTO_MINALIGN_ATTR;

struct dm_crypt_request {
        struct convert_context *ctx;
        struct scatterlist sg_in[4];
        struct scatterlist sg_out[4];
        u64 iv_sector;
};

struct crypt_config;

struct crypt_iv_operations {
        int (*ctr)(struct crypt_config *cc, struct dm_target *ti,
                   const char *opts);
        void (*dtr)(struct crypt_config *cc);
        int (*init)(struct crypt_config *cc);
        int (*wipe)(struct crypt_config *cc);
        int (*generator)(struct crypt_config *cc, u8 *iv,
                         struct dm_crypt_request *dmreq);
        int (*post)(struct crypt_config *cc, u8 *iv,
                    struct dm_crypt_request *dmreq);
};

struct iv_essiv_private {
        struct crypto_shash *hash_tfm;
        u8 *salt;
};

struct iv_benbi_private {
        int shift;
};

#define LMK_SEED_SIZE 64 /* hash + 0 */
struct iv_lmk_private {
        struct crypto_shash *hash_tfm;
        u8 *seed;
};

#define TCW_WHITENING_SIZE 16
struct iv_tcw_private {
        struct crypto_shash *crc32_tfm;
        u8 *iv_seed;
        u8 *whitening;
};

struct iv_eboiv_private {
        struct crypto_cipher *tfm;
};

/*
 * Crypt: maps a linear range of a block device
 * and encrypts / decrypts at the same time.
 */
enum flags { DM_CRYPT_SUSPENDED, DM_CRYPT_KEY_VALID,
             DM_CRYPT_SAME_CPU, DM_CRYPT_NO_OFFLOAD };

enum cipher_flags {
        CRYPT_MODE_INTEGRITY_AEAD,      /* Use authenticated mode for cihper */
        CRYPT_IV_LARGE_SECTORS,         /* Calculate IV from sector_size, not 512B sectors */
};

/*
 * The fields in here must be read only after initialization.
 */
struct crypt_config {
        struct dm_dev *dev;
        sector_t start;

        struct percpu_counter n_allocated_pages;

        struct workqueue_struct *io_queue;
        struct workqueue_struct *crypt_queue;

        spinlock_t write_thread_lock;
        struct task_struct *write_thread;
        struct rb_root write_tree;

        char *cipher;
        char *cipher_string;
        char *cipher_auth;
        char *key_string;

        const struct crypt_iv_operations *iv_gen_ops;
        union {
                struct iv_essiv_private essiv;
                struct iv_benbi_private benbi;
                struct iv_lmk_private lmk;
                struct iv_tcw_private tcw;
                struct iv_eboiv_private eboiv;
        } iv_gen_private;
        u64 iv_offset;
        unsigned int iv_size;
        unsigned short int sector_size;
        unsigned char sector_shift;

        /* ESSIV: struct crypto_cipher *essiv_tfm */
        void *iv_private;
        union {
                struct crypto_skcipher **tfms;
                struct crypto_aead **tfms_aead;
        } cipher_tfm;
        unsigned tfms_count;
        unsigned long cipher_flags;

        /*
         * Layout of each crypto request:
         *
         *   struct skcipher_request
         *      context
         *      padding
         *   struct dm_crypt_request
         *      padding
         *   IV
         *
         * The padding is added so that dm_crypt_request and the IV are
         * correctly aligned.
         */
        unsigned int dmreq_start;

        unsigned int per_bio_data_size;

        unsigned long flags;
        unsigned int key_size;
        unsigned int key_parts;      /* independent parts in key buffer */
        unsigned int key_extra_size; /* additional keys length */
        unsigned int key_mac_size;   /* MAC key size for authenc(...) */

        unsigned int integrity_tag_size;
        unsigned int integrity_iv_size;
        unsigned int on_disk_tag_size;

        /*
         * pool for per bio private data, crypto requests,
         * encryption requeusts/buffer pages and integrity tags
         */
        unsigned tag_pool_max_sectors;
        mempool_t tag_pool;
        mempool_t req_pool;
        mempool_t page_pool;

        struct bio_set bs;
        struct mutex bio_alloc_lock;

        u8 *authenc_key; /* space for keys in authenc() format (if used) */
        u8 key[0];
};

#define MIN_IOS         64
#define MAX_TAG_SIZE    480
#define POOL_ENTRY_SIZE 512

static DEFINE_SPINLOCK(dm_crypt_clients_lock);
static unsigned dm_crypt_clients_n = 0;
static volatile unsigned long dm_crypt_pages_per_client;
#define DM_CRYPT_MEMORY_PERCENT                 2
#define DM_CRYPT_MIN_PAGES_PER_CLIENT           (BIO_MAX_PAGES * 16)

static void clone_init(struct dm_crypt_io *, struct bio *);
static void kcryptd_queue_crypt(struct dm_crypt_io *io);
static struct scatterlist *crypt_get_sg_data(struct crypt_config *cc,
                                             struct scatterlist *sg);

/*
 * Use this to access cipher attributes that are independent of the key.
 */
static struct crypto_skcipher *any_tfm(struct crypt_config *cc)
{
        return cc->cipher_tfm.tfms[0];
}

static struct crypto_aead *any_tfm_aead(struct crypt_config *cc)
{
        return cc->cipher_tfm.tfms_aead[0];
}

/*
 * Different IV generation algorithms:
 *
 * plain: the initial vector is the 32-bit little-endian version of the sector
 *        number, padded with zeros if necessary.
 *
 * plain64: the initial vector is the 64-bit little-endian version of the sector
 *        number, padded with zeros if necessary.
 *
 * plain64be: the initial vector is the 64-bit big-endian version of the sector
 *        number, padded with zeros if necessary.
 *
 * essiv: "encrypted sector|salt initial vector", the sector number is
 *        encrypted with the bulk cipher using a salt as key. The salt
 *        should be derived from the bulk cipher's key via hashing.
 *
 * benbi: the 64-bit "big-endian 'narrow block'-count", starting at 1
 *        (needed for LRW-32-AES and possible other narrow block modes)
 *
 * null: the initial vector is always zero.  Provides compatibility with
 *       obsolete loop_fish2 devices.  Do not use for new devices.
 *
 * lmk:  Compatible implementation of the block chaining mode used
 *       by the Loop-AES block device encryption system
 *       designed by Jari Ruusu. See http://loop-aes.sourceforge.net/
 *       It operates on full 512 byte sectors and uses CBC
 *       with an IV derived from the sector number, the data and
 *       optionally extra IV seed.
 *       This means that after decryption the first block
 *       of sector must be tweaked according to decrypted data.
 *       Loop-AES can use three encryption schemes:
 *         version 1: is plain aes-cbc mode
 *         version 2: uses 64 multikey scheme with lmk IV generator
 *         version 3: the same as version 2 with additional IV seed
 *                   (it uses 65 keys, last key is used as IV seed)
 *
 * tcw:  Compatible implementation of the block chaining mode used
 *       by the TrueCrypt device encryption system (prior to version 4.1).
 *       For more info see: https://gitlab.com/cryptsetup/cryptsetup/wikis/TrueCryptOnDiskFormat
 *       It operates on full 512 byte sectors and uses CBC
 *       with an IV derived from initial key and the sector number.
 *       In addition, whitening value is applied on every sector, whitening
 *       is calculated from initial key, sector number and mixed using CRC32.
 *       Note that this encryption scheme is vulnerable to watermarking attacks
 *       and should be used for old compatible containers access only.
 *
 * eboiv: Encrypted byte-offset IV (used in Bitlocker in CBC mode)
 *        The IV is encrypted little-endian byte-offset (with the same key
 *        and cipher as the volume).
 */

static int crypt_iv_plain_gen(struct crypt_config *cc, u8 *iv,
                              struct dm_crypt_request *dmreq)
{
        memset(iv, 0, cc->iv_size);
        *(__le32 *)iv = cpu_to_le32(dmreq->iv_sector & 0xffffffff);

        return 0;
}

static int crypt_iv_plain64_gen(struct crypt_config *cc, u8 *iv,
                                struct dm_crypt_request *dmreq)
{
        memset(iv, 0, cc->iv_size);
        *(__le64 *)iv = cpu_to_le64(dmreq->iv_sector);

        return 0;
}

static int crypt_iv_plain64be_gen(struct crypt_config *cc, u8 *iv,
                                  struct dm_crypt_request *dmreq)
{
        memset(iv, 0, cc->iv_size);
        /* iv_size is at least of size u64; usually it is 16 bytes */
        *(__be64 *)&iv[cc->iv_size - sizeof(u64)] = cpu_to_be64(dmreq->iv_sector);

        return 0;
}

/* Initialise ESSIV - compute salt but no local memory allocations */
static int crypt_iv_essiv_init(struct crypt_config *cc)
{
        struct iv_essiv_private *essiv = &cc->iv_gen_private.essiv;
        SHASH_DESC_ON_STACK(desc, essiv->hash_tfm);
        struct crypto_cipher *essiv_tfm;
        int err;

        desc->tfm = essiv->hash_tfm;

        err = crypto_shash_digest(desc, cc->key, cc->key_size, essiv->salt);
        shash_desc_zero(desc);
        if (err)
                return err;

        essiv_tfm = cc->iv_private;

        err = crypto_cipher_setkey(essiv_tfm, essiv->salt,
                            crypto_shash_digestsize(essiv->hash_tfm));
        if (err)
                return err;

        return 0;
}

/* Wipe salt and reset key derived from volume key */
static int crypt_iv_essiv_wipe(struct crypt_config *cc)
{
        struct iv_essiv_private *essiv = &cc->iv_gen_private.essiv;
        unsigned salt_size = crypto_shash_digestsize(essiv->hash_tfm);
        struct crypto_cipher *essiv_tfm;
        int r, err = 0;

        memset(essiv->salt, 0, salt_size);

        essiv_tfm = cc->iv_private;
        r = crypto_cipher_setkey(essiv_tfm, essiv->salt, salt_size);
        if (r)
                err = r;

        return err;
}

/* Allocate the cipher for ESSIV */
static struct crypto_cipher *alloc_essiv_cipher(struct crypt_config *cc,
                                                struct dm_target *ti,
                                                const u8 *salt,
                                                unsigned int saltsize)
{
        struct crypto_cipher *essiv_tfm;
        int err;

        /* Setup the essiv_tfm with the given salt */
        essiv_tfm = crypto_alloc_cipher(cc->cipher, 0, 0);
        if (IS_ERR(essiv_tfm)) {
                ti->error = "Error allocating crypto tfm for ESSIV";
                return essiv_tfm;
        }

        if (crypto_cipher_blocksize(essiv_tfm) != cc->iv_size) {
                ti->error = "Block size of ESSIV cipher does "
                            "not match IV size of block cipher";
                crypto_free_cipher(essiv_tfm);
                return ERR_PTR(-EINVAL);
        }

        err = crypto_cipher_setkey(essiv_tfm, salt, saltsize);
        if (err) {
                ti->error = "Failed to set key for ESSIV cipher";
                crypto_free_cipher(essiv_tfm);
                return ERR_PTR(err);
        }

        return essiv_tfm;
}

static void crypt_iv_essiv_dtr(struct crypt_config *cc)
{
        struct crypto_cipher *essiv_tfm;
        struct iv_essiv_private *essiv = &cc->iv_gen_private.essiv;

        crypto_free_shash(essiv->hash_tfm);
        essiv->hash_tfm = NULL;

        kzfree(essiv->salt);
        essiv->salt = NULL;

        essiv_tfm = cc->iv_private;

        if (essiv_tfm)
                crypto_free_cipher(essiv_tfm);

        cc->iv_private = NULL;
}

static int crypt_iv_essiv_ctr(struct crypt_config *cc, struct dm_target *ti,
                              const char *opts)
{
        struct crypto_cipher *essiv_tfm = NULL;
        struct crypto_shash *hash_tfm = NULL;
        u8 *salt = NULL;
        int err;

        if (!opts) {
                ti->error = "Digest algorithm missing for ESSIV mode";
                return -EINVAL;
        }

        /* Allocate hash algorithm */
        hash_tfm = crypto_alloc_shash(opts, 0, 0);
        if (IS_ERR(hash_tfm)) {
                ti->error = "Error initializing ESSIV hash";
                err = PTR_ERR(hash_tfm);
                goto bad;
        }

        salt = kzalloc(crypto_shash_digestsize(hash_tfm), GFP_KERNEL);
        if (!salt) {
                ti->error = "Error kmallocing salt storage in ESSIV";
                err = -ENOMEM;
                goto bad;
        }

        cc->iv_gen_private.essiv.salt = salt;
        cc->iv_gen_private.essiv.hash_tfm = hash_tfm;

        essiv_tfm = alloc_essiv_cipher(cc, ti, salt,
                                       crypto_shash_digestsize(hash_tfm));
        if (IS_ERR(essiv_tfm)) {
                crypt_iv_essiv_dtr(cc);
                return PTR_ERR(essiv_tfm);
        }
        cc->iv_private = essiv_tfm;

        return 0;

bad:
        if (hash_tfm && !IS_ERR(hash_tfm))
                crypto_free_shash(hash_tfm);
        kfree(salt);
        return err;
}

static int crypt_iv_essiv_gen(struct crypt_config *cc, u8 *iv,
                              struct dm_crypt_request *dmreq)
{
        struct crypto_cipher *essiv_tfm = cc->iv_private;

        memset(iv, 0, cc->iv_size);
        *(__le64 *)iv = cpu_to_le64(dmreq->iv_sector);
        crypto_cipher_encrypt_one(essiv_tfm, iv, iv);

        return 0;
}

static int crypt_iv_benbi_ctr(struct crypt_config *cc, struct dm_target *ti,
                              const char *opts)
{
        unsigned bs = crypto_skcipher_blocksize(any_tfm(cc));
        int log = ilog2(bs);

        /* we need to calculate how far we must shift the sector count
         * to get the cipher block count, we use this shift in _gen */

        if (1 << log != bs) {
                ti->error = "cypher blocksize is not a power of 2";
                return -EINVAL;
        }

        if (log > 9) {
                ti->error = "cypher blocksize is > 512";
                return -EINVAL;
        }

        cc->iv_gen_private.benbi.shift = 9 - log;

        return 0;
}

static void crypt_iv_benbi_dtr(struct crypt_config *cc)
{
}

static int crypt_iv_benbi_gen(struct crypt_config *cc, u8 *iv,
                              struct dm_crypt_request *dmreq)
{
        __be64 val;

        memset(iv, 0, cc->iv_size - sizeof(u64)); /* rest is cleared below */

        val = cpu_to_be64(((u64)dmreq->iv_sector << cc->iv_gen_private.benbi.shift) + 1);
        put_unaligned(val, (__be64 *)(iv + cc->iv_size - sizeof(u64)));

        return 0;
}

static int crypt_iv_null_gen(struct crypt_config *cc, u8 *iv,
                             struct dm_crypt_request *dmreq)
{
        memset(iv, 0, cc->iv_size);

        return 0;
}

static void crypt_iv_lmk_dtr(struct crypt_config *cc)
{
        struct iv_lmk_private *lmk = &cc->iv_gen_private.lmk;

        if (lmk->hash_tfm && !IS_ERR(lmk->hash_tfm))
                crypto_free_shash(lmk->hash_tfm);
        lmk->hash_tfm = NULL;

        kzfree(lmk->seed);
        lmk->seed = NULL;
}

static int crypt_iv_lmk_ctr(struct crypt_config *cc, struct dm_target *ti,
                            const char *opts)
{
        struct iv_lmk_private *lmk = &cc->iv_gen_private.lmk;

        if (cc->sector_size != (1 << SECTOR_SHIFT)) {
                ti->error = "Unsupported sector size for LMK";
                return -EINVAL;
        }

        lmk->hash_tfm = crypto_alloc_shash("md5", 0, 0);
        if (IS_ERR(lmk->hash_tfm)) {
                ti->error = "Error initializing LMK hash";
                return PTR_ERR(lmk->hash_tfm);
        }

        /* No seed in LMK version 2 */
        if (cc->key_parts == cc->tfms_count) {
                lmk->seed = NULL;
                return 0;
        }

        lmk->seed = kzalloc(LMK_SEED_SIZE, GFP_KERNEL);
        if (!lmk->seed) {
                crypt_iv_lmk_dtr(cc);
                ti->error = "Error kmallocing seed storage in LMK";
                return -ENOMEM;
        }

        return 0;
}

static int crypt_iv_lmk_init(struct crypt_config *cc)
{
        struct iv_lmk_private *lmk = &cc->iv_gen_private.lmk;
        int subkey_size = cc->key_size / cc->key_parts;

        /* LMK seed is on the position of LMK_KEYS + 1 key */
        if (lmk->seed)
                memcpy(lmk->seed, cc->key + (cc->tfms_count * subkey_size),
                       crypto_shash_digestsize(lmk->hash_tfm));

        return 0;
}

static int crypt_iv_lmk_wipe(struct crypt_config *cc)
{
        struct iv_lmk_private *lmk = &cc->iv_gen_private.lmk;

        if (lmk->seed)
                memset(lmk->seed, 0, LMK_SEED_SIZE);

        return 0;
}

static int crypt_iv_lmk_one(struct crypt_config *cc, u8 *iv,
                            struct dm_crypt_request *dmreq,
                            u8 *data)
{
        struct iv_lmk_private *lmk = &cc->iv_gen_private.lmk;
        SHASH_DESC_ON_STACK(desc, lmk->hash_tfm);
        struct md5_state md5state;
        __le32 buf[4];
        int i, r;

        desc->tfm = lmk->hash_tfm;

        r = crypto_shash_init(desc);
        if (r)
                return r;

        if (lmk->seed) {
                r = crypto_shash_update(desc, lmk->seed, LMK_SEED_SIZE);
                if (r)
                        return r;
        }

        /* Sector is always 512B, block size 16, add data of blocks 1-31 */
        r = crypto_shash_update(desc, data + 16, 16 * 31);
        if (r)
                return r;

        /* Sector is cropped to 56 bits here */
        buf[0] = cpu_to_le32(dmreq->iv_sector & 0xFFFFFFFF);
        buf[1] = cpu_to_le32((((u64)dmreq->iv_sector >> 32) & 0x00FFFFFF) | 0x80000000);
        buf[2] = cpu_to_le32(4024);
        buf[3] = 0;
        r = crypto_shash_update(desc, (u8 *)buf, sizeof(buf));
        if (r)
                return r;

        /* No MD5 padding here */
        r = crypto_shash_export(desc, &md5state);
        if (r)
                return r;

        for (i = 0; i < MD5_HASH_WORDS; i++)
                __cpu_to_le32s(&md5state.hash[i]);
        memcpy(iv, &md5state.hash, cc->iv_size);

        return 0;
}

static int crypt_iv_lmk_gen(struct crypt_config *cc, u8 *iv,
                            struct dm_crypt_request *dmreq)
{
        struct scatterlist *sg;
        u8 *src;
        int r = 0;

        if (bio_data_dir(dmreq->ctx->bio_in) == WRITE) {
                sg = crypt_get_sg_data(cc, dmreq->sg_in);
                src = kmap_atomic(sg_page(sg));
                r = crypt_iv_lmk_one(cc, iv, dmreq, src + sg->offset);
                kunmap_atomic(src);
        } else
                memset(iv, 0, cc->iv_size);

        return r;
}

static int crypt_iv_lmk_post(struct crypt_config *cc, u8 *iv,
                             struct dm_crypt_request *dmreq)
{
        struct scatterlist *sg;
        u8 *dst;
        int r;

        if (bio_data_dir(dmreq->ctx->bio_in) == WRITE)
                return 0;

        sg = crypt_get_sg_data(cc, dmreq->sg_out);
        dst = kmap_atomic(sg_page(sg));
        r = crypt_iv_lmk_one(cc, iv, dmreq, dst + sg->offset);

        /* Tweak the first block of plaintext sector */
        if (!r)
                crypto_xor(dst + sg->offset, iv, cc->iv_size);

        kunmap_atomic(dst);
        return r;
}

static void crypt_iv_tcw_dtr(struct crypt_config *cc)
{
        struct iv_tcw_private *tcw = &cc->iv_gen_private.tcw;

        kzfree(tcw->iv_seed);
        tcw->iv_seed = NULL;
        kzfree(tcw->whitening);
        tcw->whitening = NULL;

        if (tcw->crc32_tfm && !IS_ERR(tcw->crc32_tfm))
                crypto_free_shash(tcw->crc32_tfm);
        tcw->crc32_tfm = NULL;
}

static int crypt_iv_tcw_ctr(struct crypt_config *cc, struct dm_target *ti,
                            const char *opts)
{
        struct iv_tcw_private *tcw = &cc->iv_gen_private.tcw;

        if (cc->sector_size != (1 << SECTOR_SHIFT)) {
                ti->error = "Unsupported sector size for TCW";
                return -EINVAL;
        }

        if (cc->key_size <= (cc->iv_size + TCW_WHITENING_SIZE)) {
                ti->error = "Wrong key size for TCW";
                return -EINVAL;
        }

        tcw->crc32_tfm = crypto_alloc_shash("crc32", 0, 0);
        if (IS_ERR(tcw->crc32_tfm)) {
                ti->error = "Error initializing CRC32 in TCW";
                return PTR_ERR(tcw->crc32_tfm);
        }

        tcw->iv_seed = kzalloc(cc->iv_size, GFP_KERNEL);
        tcw->whitening = kzalloc(TCW_WHITENING_SIZE, GFP_KERNEL);
        if (!tcw->iv_seed || !tcw->whitening) {
                crypt_iv_tcw_dtr(cc);
                ti->error = "Error allocating seed storage in TCW";
                return -ENOMEM;
        }

        return 0;
}

static int crypt_iv_tcw_init(struct crypt_config *cc)
{
        struct iv_tcw_private *tcw = &cc->iv_gen_private.tcw;
        int key_offset = cc->key_size - cc->iv_size - TCW_WHITENING_SIZE;

        memcpy(tcw->iv_seed, &cc->key[key_offset], cc->iv_size);
        memcpy(tcw->whitening, &cc->key[key_offset + cc->iv_size],
               TCW_WHITENING_SIZE);

        return 0;
}

static int crypt_iv_tcw_wipe(struct crypt_config *cc)
{
        struct iv_tcw_private *tcw = &cc->iv_gen_private.tcw;

        memset(tcw->iv_seed, 0, cc->iv_size);
        memset(tcw->whitening, 0, TCW_WHITENING_SIZE);

        return 0;
}

static int crypt_iv_tcw_whitening(struct crypt_config *cc,
                                  struct dm_crypt_request *dmreq,
                                  u8 *data)
{
        struct iv_tcw_private *tcw = &cc->iv_gen_private.tcw;
        __le64 sector = cpu_to_le64(dmreq->iv_sector);
        u8 buf[TCW_WHITENING_SIZE];
        SHASH_DESC_ON_STACK(desc, tcw->crc32_tfm);
        int i, r;

        /* xor whitening with sector number */
        crypto_xor_cpy(buf, tcw->whitening, (u8 *)&sector, 8);
        crypto_xor_cpy(&buf[8], tcw->whitening + 8, (u8 *)&sector, 8);

        /* calculate crc32 for every 32bit part and xor it */
        desc->tfm = tcw->crc32_tfm;
        for (i = 0; i < 4; i++) {
                r = crypto_shash_init(desc);
                if (r)
                        goto out;
                r = crypto_shash_update(desc, &buf[i * 4], 4);
                if (r)
                        goto out;
                r = crypto_shash_final(desc, &buf[i * 4]);
                if (r)
                        goto out;
        }
        crypto_xor(&buf[0], &buf[12], 4);
        crypto_xor(&buf[4], &buf[8], 4);

        /* apply whitening (8 bytes) to whole sector */
        for (i = 0; i < ((1 << SECTOR_SHIFT) / 8); i++)
                crypto_xor(data + i * 8, buf, 8);
out:
        memzero_explicit(buf, sizeof(buf));
        return r;
}

static int crypt_iv_tcw_gen(struct crypt_config *cc, u8 *iv,
                            struct dm_crypt_request *dmreq)
{
        struct scatterlist *sg;
        struct iv_tcw_private *tcw = &cc->iv_gen_private.tcw;
        __le64 sector = cpu_to_le64(dmreq->iv_sector);
        u8 *src;
        int r = 0;

        /* Remove whitening from ciphertext */
        if (bio_data_dir(dmreq->ctx->bio_in) != WRITE) {
                sg = crypt_get_sg_data(cc, dmreq->sg_in);
                src = kmap_atomic(sg_page(sg));
                r = crypt_iv_tcw_whitening(cc, dmreq, src + sg->offset);
                kunmap_atomic(src);
        }

        /* Calculate IV */
        crypto_xor_cpy(iv, tcw->iv_seed, (u8 *)&sector, 8);
        if (cc->iv_size > 8)
                crypto_xor_cpy(&iv[8], tcw->iv_seed + 8, (u8 *)&sector,
                               cc->iv_size - 8);

        return r;
}

static int crypt_iv_tcw_post(struct crypt_config *cc, u8 *iv,
                             struct dm_crypt_request *dmreq)
{
        struct scatterlist *sg;
        u8 *dst;
        int r;

        if (bio_data_dir(dmreq->ctx->bio_in) != WRITE)
                return 0;

        /* Apply whitening on ciphertext */
        sg = crypt_get_sg_data(cc, dmreq->sg_out);
        dst = kmap_atomic(sg_page(sg));
        r = crypt_iv_tcw_whitening(cc, dmreq, dst + sg->offset);
        kunmap_atomic(dst);

        return r;
}

static int crypt_iv_random_gen(struct crypt_config *cc, u8 *iv,
                                struct dm_crypt_request *dmreq)
{
        /* Used only for writes, there must be an additional space to store IV */
        get_random_bytes(iv, cc->iv_size);
        return 0;
}

static void crypt_iv_eboiv_dtr(struct crypt_config *cc)
{
        struct iv_eboiv_private *eboiv = &cc->iv_gen_private.eboiv;

        crypto_free_cipher(eboiv->tfm);
        eboiv->tfm = NULL;
}

static int crypt_iv_eboiv_ctr(struct crypt_config *cc, struct dm_target *ti,
                            const char *opts)
{
        struct iv_eboiv_private *eboiv = &cc->iv_gen_private.eboiv;
        struct crypto_cipher *tfm;

        tfm = crypto_alloc_cipher(cc->cipher, 0, 0);
        if (IS_ERR(tfm)) {
                ti->error = "Error allocating crypto tfm for EBOIV";
                return PTR_ERR(tfm);
        }

        if (crypto_cipher_blocksize(tfm) != cc->iv_size) {
                ti->error = "Block size of EBOIV cipher does "
                            "not match IV size of block cipher";
                crypto_free_cipher(tfm);
                return -EINVAL;
        }

        eboiv->tfm = tfm;
        return 0;
}

static int crypt_iv_eboiv_init(struct crypt_config *cc)
{
        struct iv_eboiv_private *eboiv = &cc->iv_gen_private.eboiv;
        int err;

        err = crypto_cipher_setkey(eboiv->tfm, cc->key, cc->key_size);
        if (err)
                return err;

        return 0;
}

static int crypt_iv_eboiv_wipe(struct crypt_config *cc)
{
        /* Called after cc->key is set to random key in crypt_wipe() */
        return crypt_iv_eboiv_init(cc);
}

static int crypt_iv_eboiv_gen(struct crypt_config *cc, u8 *iv,
                            struct dm_crypt_request *dmreq)
{
        struct iv_eboiv_private *eboiv = &cc->iv_gen_private.eboiv;

        memset(iv, 0, cc->iv_size);
        *(__le64 *)iv = cpu_to_le64(dmreq->iv_sector * cc->sector_size);
        crypto_cipher_encrypt_one(eboiv->tfm, iv, iv);

        return 0;
}

static const struct crypt_iv_operations crypt_iv_plain_ops = {
        .generator = crypt_iv_plain_gen
};

static const struct crypt_iv_operations crypt_iv_plain64_ops = {
        .generator = crypt_iv_plain64_gen
};

static const struct crypt_iv_operations crypt_iv_plain64be_ops = {
        .generator = crypt_iv_plain64be_gen
};

static const struct crypt_iv_operations crypt_iv_essiv_ops = {
        .ctr       = crypt_iv_essiv_ctr,
        .dtr       = crypt_iv_essiv_dtr,
        .init      = crypt_iv_essiv_init,
        .wipe      = crypt_iv_essiv_wipe,
        .generator = crypt_iv_essiv_gen
};

static const struct crypt_iv_operations crypt_iv_benbi_ops = {
        .ctr       = crypt_iv_benbi_ctr,
        .dtr       = crypt_iv_benbi_dtr,
        .generator = crypt_iv_benbi_gen
};

static const struct crypt_iv_operations crypt_iv_null_ops = {
        .generator = crypt_iv_null_gen
};

static const struct crypt_iv_operations crypt_iv_lmk_ops = {
        .ctr       = crypt_iv_lmk_ctr,
        .dtr       = crypt_iv_lmk_dtr,
        .init      = crypt_iv_lmk_init,
        .wipe      = crypt_iv_lmk_wipe,
        .generator = crypt_iv_lmk_gen,
        .post      = crypt_iv_lmk_post
};

static const struct crypt_iv_operations crypt_iv_tcw_ops = {
        .ctr       = crypt_iv_tcw_ctr,
        .dtr       = crypt_iv_tcw_dtr,
        .init      = crypt_iv_tcw_init,
        .wipe      = crypt_iv_tcw_wipe,
        .generator = crypt_iv_tcw_gen,
        .post      = crypt_iv_tcw_post
};

static struct crypt_iv_operations crypt_iv_random_ops = {
        .generator = crypt_iv_random_gen
};

static struct crypt_iv_operations crypt_iv_eboiv_ops = {
        .ctr       = crypt_iv_eboiv_ctr,
        .dtr       = crypt_iv_eboiv_dtr,
        .init      = crypt_iv_eboiv_init,
        .wipe      = crypt_iv_eboiv_wipe,
        .generator = crypt_iv_eboiv_gen
};

/*
 * Integrity extensions
 */
static bool crypt_integrity_aead(struct crypt_config *cc)
{
        return test_bit(CRYPT_MODE_INTEGRITY_AEAD, &cc->cipher_flags);
}

static bool crypt_integrity_hmac(struct crypt_config *cc)
{
        return crypt_integrity_aead(cc) && cc->key_mac_size;
}

/* Get sg containing data */
static struct scatterlist *crypt_get_sg_data(struct crypt_config *cc,
                                             struct scatterlist *sg)
{
        if (unlikely(crypt_integrity_aead(cc)))
                return &sg[2];

        return sg;
}

static int dm_crypt_integrity_io_alloc(struct dm_crypt_io *io, struct bio *bio)
{
        struct bio_integrity_payload *bip;
        unsigned int tag_len;
        int ret;

        if (!bio_sectors(bio) || !io->cc->on_disk_tag_size)

                return 0;

        bip = bio_integrity_alloc(bio, GFP_NOIO, 1);
        if (IS_ERR(bip))
                return PTR_ERR(bip);

        tag_len = io->cc->on_disk_tag_size * (bio_sectors(bio) >> io->cc->sector_shift);

        bip->bip_iter.bi_size = tag_len;
        bip->bip_iter.bi_sector = io->cc->start + io->sector;

        ret = bio_integrity_add_page(bio, virt_to_page(io->integrity_metadata),
                                     tag_len, offset_in_page(io->integrity_metadata));
        if (unlikely(ret != tag_len))
                return -ENOMEM;

        return 0;
}

static int crypt_integrity_ctr(struct crypt_config *cc, struct dm_target *ti)
{
#ifdef CONFIG_BLK_DEV_INTEGRITY
        struct blk_integrity *bi = blk_get_integrity(cc->dev->bdev->bd_disk);
        struct mapped_device *md = dm_table_get_md(ti->table);

        /* From now we require underlying device with our integrity profile */
        if (!bi || strcasecmp(bi->profile->name, "DM-DIF-EXT-TAG")) {
                ti->error = "Integrity profile not supported.";
                return -EINVAL;
        }

        if (bi->tag_size != cc->on_disk_tag_size ||
            bi->tuple_size != cc->on_disk_tag_size) {
                ti->error = "Integrity profile tag size mismatch.";
                return -EINVAL;
        }
        if (1 << bi->interval_exp != cc->sector_size) {
                ti->error = "Integrity profile sector size mismatch.";
                return -EINVAL;
        }

        if (crypt_integrity_aead(cc)) {
                cc->integrity_tag_size = cc->on_disk_tag_size - cc->integrity_iv_size;
                DMDEBUG("%s: Integrity AEAD, tag size %u, IV size %u.", dm_device_name(md),
                       cc->integrity_tag_size, cc->integrity_iv_size);

                if (crypto_aead_setauthsize(any_tfm_aead(cc), cc->integrity_tag_size)) {
                        ti->error = "Integrity AEAD auth tag size is not supported.";
                        return -EINVAL;
                }
        } else if (cc->integrity_iv_size)
                DMDEBUG("%s: Additional per-sector space %u bytes for IV.", dm_device_name(md),
                       cc->integrity_iv_size);

        if ((cc->integrity_tag_size + cc->integrity_iv_size) != bi->tag_size) {
                ti->error = "Not enough space for integrity tag in the profile.";
                return -EINVAL;
        }

        return 0;
#else
        ti->error = "Integrity profile not supported.";
        return -EINVAL;
#endif
}

static void crypt_convert_init(struct crypt_config *cc,
                               struct convert_context *ctx,
                               struct bio *bio_out, struct bio *bio_in,
                               sector_t sector)
{
        ctx->bio_in = bio_in;
        ctx->bio_out = bio_out;
        if (bio_in)
                ctx->iter_in = bio_in->bi_iter;
        if (bio_out)
                ctx->iter_out = bio_out->bi_iter;
        ctx->cc_sector = sector + cc->iv_offset;
        init_completion(&ctx->restart);
}

static struct dm_crypt_request *dmreq_of_req(struct crypt_config *cc,
                                             void *req)
{
        return (struct dm_crypt_request *)((char *)req + cc->dmreq_start);
}

static void *req_of_dmreq(struct crypt_config *cc, struct dm_crypt_request *dmreq)
{
        return (void *)((char *)dmreq - cc->dmreq_start);
}

static u8 *iv_of_dmreq(struct crypt_config *cc,
                       struct dm_crypt_request *dmreq)
{
        if (crypt_integrity_aead(cc))
                return (u8 *)ALIGN((unsigned long)(dmreq + 1),
                        crypto_aead_alignmask(any_tfm_aead(cc)) + 1);
        else
                return (u8 *)ALIGN((unsigned long)(dmreq + 1),
                        crypto_skcipher_alignmask(any_tfm(cc)) + 1);
}

static u8 *org_iv_of_dmreq(struct crypt_config *cc,
                       struct dm_crypt_request *dmreq)
{
        return iv_of_dmreq(cc, dmreq) + cc->iv_size;
}

static __le64 *org_sector_of_dmreq(struct crypt_config *cc,
                       struct dm_crypt_request *dmreq)
{
        u8 *ptr = iv_of_dmreq(cc, dmreq) + cc->iv_size + cc->iv_size;
        return (__le64 *) ptr;
}

static unsigned int *org_tag_of_dmreq(struct crypt_config *cc,
                       struct dm_crypt_request *dmreq)
{
        u8 *ptr = iv_of_dmreq(cc, dmreq) + cc->iv_size +
                  cc->iv_size + sizeof(uint64_t);
        return (unsigned int*)ptr;
}

static void *tag_from_dmreq(struct crypt_config *cc,
                                struct dm_crypt_request *dmreq)
{
        struct convert_context *ctx = dmreq->ctx;
        struct dm_crypt_io *io = container_of(ctx, struct dm_crypt_io, ctx);

        return &io->integrity_metadata[*org_tag_of_dmreq(cc, dmreq) *
                cc->on_disk_tag_size];
}

static void *iv_tag_from_dmreq(struct crypt_config *cc,
                               struct dm_crypt_request *dmreq)
{
        return tag_from_dmreq(cc, dmreq) + cc->integrity_tag_size;
}

static int crypt_convert_block_aead(struct crypt_config *cc,
                                     struct convert_context *ctx,
                                     struct aead_request *req,
                                     unsigned int tag_offset)
{
        struct bio_vec bv_in = bio_iter_iovec(ctx->bio_in, ctx->iter_in);
        struct bio_vec bv_out = bio_iter_iovec(ctx->bio_out, ctx->iter_out);
        struct dm_crypt_request *dmreq;
        u8 *iv, *org_iv, *tag_iv, *tag;
        __le64 *sector;
        int r = 0;

        BUG_ON(cc->integrity_iv_size && cc->integrity_iv_size != cc->iv_size);

        /* Reject unexpected unaligned bio. */
        if (unlikely(bv_in.bv_len & (cc->sector_size - 1)))
                return -EIO;

        dmreq = dmreq_of_req(cc, req);
        dmreq->iv_sector = ctx->cc_sector;
        if (test_bit(CRYPT_IV_LARGE_SECTORS, &cc->cipher_flags))
                dmreq->iv_sector >>= cc->sector_shift;
        dmreq->ctx = ctx;

        *org_tag_of_dmreq(cc, dmreq) = tag_offset;

        sector = org_sector_of_dmreq(cc, dmreq);
        *sector = cpu_to_le64(ctx->cc_sector - cc->iv_offset);

        iv = iv_of_dmreq(cc, dmreq);
        org_iv = org_iv_of_dmreq(cc, dmreq);
        tag = tag_from_dmreq(cc, dmreq);
        tag_iv = iv_tag_from_dmreq(cc, dmreq);

        /* AEAD request:
         *  |----- AAD -------|------ DATA -------|-- AUTH TAG --|
         *  | (authenticated) | (auth+encryption) |              |
         *  | sector_LE |  IV |  sector in/out    |  tag in/out  |
         */
        sg_init_table(dmreq->sg_in, 4);
        sg_set_buf(&dmreq->sg_in[0], sector, sizeof(uint64_t));
        sg_set_buf(&dmreq->sg_in[1], org_iv, cc->iv_size);
        sg_set_page(&dmreq->sg_in[2], bv_in.bv_page, cc->sector_size, bv_in.bv_offset);
        sg_set_buf(&dmreq->sg_in[3], tag, cc->integrity_tag_size);

        sg_init_table(dmreq->sg_out, 4);
        sg_set_buf(&dmreq->sg_out[0], sector, sizeof(uint64_t));
        sg_set_buf(&dmreq->sg_out[1], org_iv, cc->iv_size);
        sg_set_page(&dmreq->sg_out[2], bv_out.bv_page, cc->sector_size, bv_out.bv_offset);
        sg_set_buf(&dmreq->sg_out[3], tag, cc->integrity_tag_size);

        if (cc->iv_gen_ops) {
                /* For READs use IV stored in integrity metadata */
                if (cc->integrity_iv_size && bio_data_dir(ctx->bio_in) != WRITE) {
                        memcpy(org_iv, tag_iv, cc->iv_size);
                } else {
                        r = cc->iv_gen_ops->generator(cc, org_iv, dmreq);
                        if (r < 0)
                                return r;
                        /* Store generated IV in integrity metadata */
                        if (cc->integrity_iv_size)
                                memcpy(tag_iv, org_iv, cc->iv_size);
                }
                /* Working copy of IV, to be modified in crypto API */
                memcpy(iv, org_iv, cc->iv_size);
        }

        aead_request_set_ad(req, sizeof(uint64_t) + cc->iv_size);
        if (bio_data_dir(ctx->bio_in) == WRITE) {
                aead_request_set_crypt(req, dmreq->sg_in, dmreq->sg_out,
                                       cc->sector_size, iv);
                r = crypto_aead_encrypt(req);
                if (cc->integrity_tag_size + cc->integrity_iv_size != cc->on_disk_tag_size)
                        memset(tag + cc->integrity_tag_size + cc->integrity_iv_size, 0,
                               cc->on_disk_tag_size - (cc->integrity_tag_size + cc->integrity_iv_size));
        } else {
                aead_request_set_crypt(req, dmreq->sg_in, dmreq->sg_out,
                                       cc->sector_size + cc->integrity_tag_size, iv);
                r = crypto_aead_decrypt(req);
        }

        if (r == -EBADMSG) {
                char b[BDEVNAME_SIZE];
                DMERR_LIMIT("%s: INTEGRITY AEAD ERROR, sector %llu", bio_devname(ctx->bio_in, b),
                            (unsigned long long)le64_to_cpu(*sector));
        }

        if (!r && cc->iv_gen_ops && cc->iv_gen_ops->post)
                r = cc->iv_gen_ops->post(cc, org_iv, dmreq);

        bio_advance_iter(ctx->bio_in, &ctx->iter_in, cc->sector_size);
        bio_advance_iter(ctx->bio_out, &ctx->iter_out, cc->sector_size);

        return r;
}

static int crypt_convert_block_skcipher(struct crypt_config *cc,
                                        struct convert_context *ctx,
                                        struct skcipher_request *req,
                                        unsigned int tag_offset)
{
        struct bio_vec bv_in = bio_iter_iovec(ctx->bio_in, ctx->iter_in);
        struct bio_vec bv_out = bio_iter_iovec(ctx->bio_out, ctx->iter_out);
        struct scatterlist *sg_in, *sg_out;
        struct dm_crypt_request *dmreq;
        u8 *iv, *org_iv, *tag_iv;
        __le64 *sector;
        int r = 0;

        /* Reject unexpected unaligned bio. */
        if (unlikely(bv_in.bv_len & (cc->sector_size - 1)))
                return -EIO;

        dmreq = dmreq_of_req(cc, req);
        dmreq->iv_sector = ctx->cc_sector;
        if (test_bit(CRYPT_IV_LARGE_SECTORS, &cc->cipher_flags))
                dmreq->iv_sector >>= cc->sector_shift;
        dmreq->ctx = ctx;

        *org_tag_of_dmreq(cc, dmreq) = tag_offset;

        iv = iv_of_dmreq(cc, dmreq);
        org_iv = org_iv_of_dmreq(cc, dmreq);
        tag_iv = iv_tag_from_dmreq(cc, dmreq);

        sector = org_sector_of_dmreq(cc, dmreq);
        *sector = cpu_to_le64(ctx->cc_sector - cc->iv_offset);

        /* For skcipher we use only the first sg item */
        sg_in  = &dmreq->sg_in[0];
        sg_out = &dmreq->sg_out[0];

        sg_init_table(sg_in, 1);
        sg_set_page(sg_in, bv_in.bv_page, cc->sector_size, bv_in.bv_offset);

        sg_init_table(sg_out, 1);
        sg_set_page(sg_out, bv_out.bv_page, cc->sector_size, bv_out.bv_offset);

        if (cc->iv_gen_ops) {
                /* For READs use IV stored in integrity metadata */
                if (cc->integrity_iv_size && bio_data_dir(ctx->bio_in) != WRITE) {
                        memcpy(org_iv, tag_iv, cc->integrity_iv_size);
                } else {
                        r = cc->iv_gen_ops->generator(cc, org_iv, dmreq);
                        if (r < 0)
                                return r;
                        /* Store generated IV in integrity metadata */
                        if (cc->integrity_iv_size)
                                memcpy(tag_iv, org_iv, cc->integrity_iv_size);
                }
                /* Working copy of IV, to be modified in crypto API */
                memcpy(iv, org_iv, cc->iv_size);
        }

        skcipher_request_set_crypt(req, sg_in, sg_out, cc->sector_size, iv);

        if (bio_data_dir(ctx->bio_in) == WRITE)
                r = crypto_skcipher_encrypt(req);
        else
                r = crypto_skcipher_decrypt(req);

        if (!r && cc->iv_gen_ops && cc->iv_gen_ops->post)
                r = cc->iv_gen_ops->post(cc, org_iv, dmreq);

        bio_advance_iter(ctx->bio_in, &ctx->iter_in, cc->sector_size);
        bio_advance_iter(ctx->bio_out, &ctx->iter_out, cc->sector_size);

        return r;
}

static void kcryptd_async_done(struct crypto_async_request *async_req,
                               int error);

static void crypt_alloc_req_skcipher(struct crypt_config *cc,
                                     struct convert_context *ctx)
{
        unsigned key_index = ctx->cc_sector & (cc->tfms_count - 1);

        if (!ctx->r.req)
                ctx->r.req = mempool_alloc(&cc->req_pool, GFP_NOIO);

        skcipher_request_set_tfm(ctx->r.req, cc->cipher_tfm.tfms[key_index]);

        /*
         * Use REQ_MAY_BACKLOG so a cipher driver internally backlogs
         * requests if driver request queue is full.
         */
        skcipher_request_set_callback(ctx->r.req,
            CRYPTO_TFM_REQ_MAY_BACKLOG,
            kcryptd_async_done, dmreq_of_req(cc, ctx->r.req));
}

static void crypt_alloc_req_aead(struct crypt_config *cc,
                                 struct convert_context *ctx)
{
        if (!ctx->r.req_aead)
                ctx->r.req_aead = mempool_alloc(&cc->req_pool, GFP_NOIO);

        aead_request_set_tfm(ctx->r.req_aead, cc->cipher_tfm.tfms_aead[0]);

        /*
         * Use REQ_MAY_BACKLOG so a cipher driver internally backlogs
         * requests if driver request queue is full.
         */
        aead_request_set_callback(ctx->r.req_aead,
            CRYPTO_TFM_REQ_MAY_BACKLOG,
            kcryptd_async_done, dmreq_of_req(cc, ctx->r.req_aead));
}

static void crypt_alloc_req(struct crypt_config *cc,
                            struct convert_context *ctx)
{
        if (crypt_integrity_aead(cc))
                crypt_alloc_req_aead(cc, ctx);
        else
                crypt_alloc_req_skcipher(cc, ctx);
}

static void crypt_free_req_skcipher(struct crypt_config *cc,
                                    struct skcipher_request *req, struct bio *base_bio)
{
        struct dm_crypt_io *io = dm_per_bio_data(base_bio, cc->per_bio_data_size);

        if ((struct skcipher_request *)(io + 1) != req)
                mempool_free(req, &cc->req_pool);
}

static void crypt_free_req_aead(struct crypt_config *cc,
                                struct aead_request *req, struct bio *base_bio)
{
        struct dm_crypt_io *io = dm_per_bio_data(base_bio, cc->per_bio_data_size);

        if ((struct aead_request *)(io + 1) != req)
                mempool_free(req, &cc->req_pool);
}

static void crypt_free_req(struct crypt_config *cc, void *req, struct bio *base_bio)
{
        if (crypt_integrity_aead(cc))
                crypt_free_req_aead(cc, req, base_bio);
        else
                crypt_free_req_skcipher(cc, req, base_bio);
}

/*
 * Encrypt / decrypt data from one bio to another one (can be the same one)
 */
static blk_status_t crypt_convert(struct crypt_config *cc,
                         struct convert_context *ctx)
{
        unsigned int tag_offset = 0;
        unsigned int sector_step = cc->sector_size >> SECTOR_SHIFT;
        int r;

        atomic_set(&ctx->cc_pending, 1);

        while (ctx->iter_in.bi_size && ctx->iter_out.bi_size) {

                crypt_alloc_req(cc, ctx);
                atomic_inc(&ctx->cc_pending);

                if (crypt_integrity_aead(cc))
                        r = crypt_convert_block_aead(cc, ctx, ctx->r.req_aead, tag_offset);
                else
                        r = crypt_convert_block_skcipher(cc, ctx, ctx->r.req, tag_offset);

                switch (r) {
                /*
                 * The request was queued by a crypto driver
                 * but the driver request queue is full, let's wait.
                 */
                case -EBUSY:
                        wait_for_completion(&ctx->restart);
                        reinit_completion(&ctx->restart);
                        /* fall through */
                /*
                 * The request is queued and processed asynchronously,
                 * completion function kcryptd_async_done() will be called.
                 */
                case -EINPROGRESS:
                        ctx->r.req = NULL;
                        ctx->cc_sector += sector_step;
                        tag_offset++;
                        continue;
                /*
                 * The request was already processed (synchronously).
                 */
                case 0:
                        atomic_dec(&ctx->cc_pending);
                        ctx->cc_sector += sector_step;
                        tag_offset++;
                        cond_resched();
                        continue;
                /*
                 * There was a data integrity error.
                 */
                case -EBADMSG:
                        atomic_dec(&ctx->cc_pending);
                        return BLK_STS_PROTECTION;
                /*
                 * There was an error while processing the request.
                 */
                default:
                        atomic_dec(&ctx->cc_pending);
                        return BLK_STS_IOERR;
                }
        }

        return 0;
}

static void crypt_free_buffer_pages(struct crypt_config *cc, struct bio *clone);

/*
 * Generate a new unfragmented bio with the given size
 * This should never violate the device limitations (but only because
 * max_segment_size is being constrained to PAGE_SIZE).
 *
 * This function may be called concurrently. If we allocate from the mempool
 * concurrently, there is a possibility of deadlock. For example, if we have
 * mempool of 256 pages, two processes, each wanting 256, pages allocate from
 * the mempool concurrently, it may deadlock in a situation where both processes
 * have allocated 128 pages and the mempool is exhausted.
 *
 * In order to avoid this scenario we allocate the pages under a mutex.
 *
 * In order to not degrade performance with excessive locking, we try
 * non-blocking allocations without a mutex first but on failure we fallback
 * to blocking allocations with a mutex.
 */
static struct bio *crypt_alloc_buffer(struct dm_crypt_io *io, unsigned size)
{
        struct crypt_config *cc = io->cc;
        struct bio *clone;
        unsigned int nr_iovecs = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
        gfp_t gfp_mask = GFP_NOWAIT | __GFP_HIGHMEM;
        unsigned i, len, remaining_size;
        struct page *page;

retry:
        if (unlikely(gfp_mask & __GFP_DIRECT_RECLAIM))
                mutex_lock(&cc->bio_alloc_lock);

        clone = bio_alloc_bioset(GFP_NOIO, nr_iovecs, &cc->bs);
        if (!clone)
                goto out;

        clone_init(io, clone);

        remaining_size = size;

        for (i = 0; i < nr_iovecs; i++) {
                page = mempool_alloc(&cc->page_pool, gfp_mask);
                if (!page) {
                        crypt_free_buffer_pages(cc, clone);
                        bio_put(clone);
                        gfp_mask |= __GFP_DIRECT_RECLAIM;
                        goto retry;
                }

                len = (remaining_size > PAGE_SIZE) ? PAGE_SIZE : remaining_size;

                bio_add_page(clone, page, len, 0);

                remaining_size -= len;
        }

        /* Allocate space for integrity tags */
        if (dm_crypt_integrity_io_alloc(io, clone)) {
                crypt_free_buffer_pages(cc, clone);
                bio_put(clone);
                clone = NULL;
        }
out:
        if (unlikely(gfp_mask & __GFP_DIRECT_RECLAIM))
                mutex_unlock(&cc->bio_alloc_lock);

        return clone;
}

static void crypt_free_buffer_pages(struct crypt_config *cc, struct bio *clone)
{
        struct bio_vec *bv;
        struct bvec_iter_all iter_all;

        bio_for_each_segment_all(bv, clone, iter_all) {
                BUG_ON(!bv->bv_page);
                mempool_free(bv->bv_page, &cc->page_pool);
        }
}

static void crypt_io_init(struct dm_crypt_io *io, struct crypt_config *cc,
                          struct bio *bio, sector_t sector)
{
        io->cc = cc;
        io->base_bio = bio;
        io->sector = sector;
        io->error = 0;
        io->ctx.r.req = NULL;
        io->integrity_metadata = NULL;
        io->integrity_metadata_from_pool = false;
        atomic_set(&io->io_pending, 0);
}

static void crypt_inc_pending(struct dm_crypt_io *io)
{
        atomic_inc(&io->io_pending);
}

/*
 * One of the bios was finished. Check for completion of
 * the whole request and correctly clean up the buffer.
 */
static void crypt_dec_pending(struct dm_crypt_io *io)
{
        struct crypt_config *cc = io->cc;
        struct bio *base_bio = io->base_bio;
        blk_status_t error = io->error;

        if (!atomic_dec_and_test(&io->io_pending))
                return;

        if (io->ctx.r.req)
                crypt_free_req(cc, io->ctx.r.req, base_bio);

        if (unlikely(io->integrity_metadata_from_pool))
                mempool_free(io->integrity_metadata, &io->cc->tag_pool);
        else
                kfree(io->integrity_metadata);

        base_bio->bi_status = error;
        bio_endio(base_bio);
}

/*
 * kcryptd/kcryptd_io:
 *
 * Needed because it would be very unwise to do decryption in an
 * interrupt context.
 *
 * kcryptd performs the actual encryption or decryption.
 *
 * kcryptd_io performs the IO submission.
 *
 * They must be separated as otherwise the final stages could be
 * starved by new requests which can block in the first stages due
 * to memory allocation.
 *
 * The work is done per CPU global for all dm-crypt instances.
 * They should not depend on each other and do not block.
 */
static void crypt_endio(struct bio *clone)
{
        struct dm_crypt_io *io = clone->bi_private;
        struct crypt_config *cc = io->cc;
        unsigned rw = bio_data_dir(clone);
        blk_status_t error;

        /*
         * free the processed pages
         */
        if (rw == WRITE)
                crypt_free_buffer_pages(cc, clone);

        error = clone->bi_status;
        bio_put(clone);

        if (rw == READ && !error) {
                kcryptd_queue_crypt(io);
                return;
        }

        if (unlikely(error))
                io->error = error;

        crypt_dec_pending(io);
}

static void clone_init(struct dm_crypt_io *io, struct bio *clone)
{
        struct crypt_config *cc = io->cc;

        clone->bi_private = io;
        clone->bi_end_io  = crypt_endio;
        bio_set_dev(clone, cc->dev->bdev);
        clone->bi_opf     = io->base_bio->bi_opf;
}

static int kcryptd_io_read(struct dm_crypt_io *io, gfp_t gfp)
{
        struct crypt_config *cc = io->cc;
        struct bio *clone;

        /*
         * We need the original biovec array in order to decrypt
         * the whole bio data *afterwards* -- thanks to immutable
         * biovecs we don't need to worry about the block layer
         * modifying the biovec array; so leverage bio_clone_fast().
         */
        clone = bio_clone_fast(io->base_bio, gfp, &cc->bs);
        if (!clone)
                return 1;

        crypt_inc_pending(io);

        clone_init(io, clone);
        clone->bi_iter.bi_sector = cc->start + io->sector;

        if (dm_crypt_integrity_io_alloc(io, clone)) {
                crypt_dec_pending(io);
                bio_put(clone);
                return 1;
        }

        generic_make_request(clone);
        return 0;
}

static void kcryptd_io_read_work(struct work_struct *work)
{
        struct dm_crypt_io *io = container_of(work, struct dm_crypt_io, work);

        crypt_inc_pending(io);
        if (kcryptd_io_read(io, GFP_NOIO))
                io->error = BLK_STS_RESOURCE;
        crypt_dec_pending(io);
}

static void kcryptd_queue_read(struct dm_crypt_io *io)
{
        struct crypt_config *cc = io->cc;

        INIT_WORK(&io->work, kcryptd_io_read_work);
        queue_work(cc->io_queue, &io->work);
}

static void kcryptd_io_write(struct dm_crypt_io *io)
{
        struct bio *clone = io->ctx.bio_out;

        generic_make_request(clone);
}

#define crypt_io_from_node(node) rb_entry((node), struct dm_crypt_io, rb_node)

static int dmcrypt_write(void *data)
{
        struct crypt_config *cc = data;
        struct dm_crypt_io *io;

        while (1) {
                struct rb_root write_tree;
                struct blk_plug plug;

                spin_lock_irq(&cc->write_thread_lock);
continue_locked:

                if (!RB_EMPTY_ROOT(&cc->write_tree))
                        goto pop_from_list;

                set_current_state(TASK_INTERRUPTIBLE);

                spin_unlock_irq(&cc->write_thread_lock);

                if (unlikely(kthread_should_stop())) {
                        set_current_state(TASK_RUNNING);
                        break;
                }

                schedule();

                set_current_state(TASK_RUNNING);
                spin_lock_irq(&cc->write_thread_lock);
                goto continue_locked;

pop_from_list:
                write_tree = cc->write_tree;
                cc->write_tree = RB_ROOT;
                spin_unlock_irq(&cc->write_thread_lock);

                BUG_ON(rb_parent(write_tree.rb_node));

                /*
                 * Note: we cannot walk the tree here with rb_next because
                 * the structures may be freed when kcryptd_io_write is called.
                 */
                blk_start_plug(&plug);
                do {
                        io = crypt_io_from_node(rb_first(&write_tree));
                        rb_erase(&io->rb_node, &write_tree);
                        kcryptd_io_write(io);
                } while (!RB_EMPTY_ROOT(&write_tree));
                blk_finish_plug(&plug);
        }
        return 0;
}

static void kcryptd_crypt_write_io_submit(struct dm_crypt_io *io, int async)
{
        struct bio *clone = io->ctx.bio_out;
        struct crypt_config *cc = io->cc;
        unsigned long flags;
        sector_t sector;
        struct rb_node **rbp, *parent;

        if (unlikely(io->error)) {
                crypt_free_buffer_pages(cc, clone);
                bio_put(clone);
                crypt_dec_pending(io);
                return;
        }

        /* crypt_convert should have filled the clone bio */
        BUG_ON(io->ctx.iter_out.bi_size);

        clone->bi_iter.bi_sector = cc->start + io->sector;

        if (likely(!async) && test_bit(DM_CRYPT_NO_OFFLOAD, &cc->flags)) {
                generic_make_request(clone);
                return;
        }

        spin_lock_irqsave(&cc->write_thread_lock, flags);
        if (RB_EMPTY_ROOT(&cc->write_tree))
                wake_up_process(cc->write_thread);
        rbp = &cc->write_tree.rb_node;
        parent = NULL;
        sector = io->sector;
        while (*rbp) {
                parent = *rbp;
                if (sector < crypt_io_from_node(parent)->sector)
                        rbp = &(*rbp)->rb_left;
                else
                        rbp = &(*rbp)->rb_right;
        }
        rb_link_node(&io->rb_node, parent, rbp);
        rb_insert_color(&io->rb_node, &cc->write_tree);
        spin_unlock_irqrestore(&cc->write_thread_lock, flags);
}

static void kcryptd_crypt_write_convert(struct dm_crypt_io *io)
{
        struct crypt_config *cc = io->cc;
        struct bio *clone;
        int crypt_finished;
        sector_t sector = io->sector;
        blk_status_t r;

        /*
         * Prevent io from disappearing until this function completes.
         */
        crypt_inc_pending(io);
        crypt_convert_init(cc, &io->ctx, NULL, io->base_bio, sector);

        clone = crypt_alloc_buffer(io, io->base_bio->bi_iter.bi_size);
        if (unlikely(!clone)) {
                io->error = BLK_STS_IOERR;
                goto dec;
        }

        io->ctx.bio_out = clone;
        io->ctx.iter_out = clone->bi_iter;

        sector += bio_sectors(clone);

        crypt_inc_pending(io);
        r = crypt_convert(cc, &io->ctx);
        if (r)
                io->error = r;
        crypt_finished = atomic_dec_and_test(&io->ctx.cc_pending);

        /* Encryption was already finished, submit io now */
        if (crypt_finished) {
                kcryptd_crypt_write_io_submit(io, 0);
                io->sector = sector;
        }

dec:
        crypt_dec_pending(io);
}

static void kcryptd_crypt_read_done(struct dm_crypt_io *io)
{
        crypt_dec_pending(io);
}

static void kcryptd_crypt_read_convert(struct dm_crypt_io *io)
{
        struct crypt_config *cc = io->cc;
        blk_status_t r;

        crypt_inc_pending(io);

        crypt_convert_init(cc, &io->ctx, io->base_bio, io->base_bio,
                           io->sector);

        r = crypt_convert(cc, &io->ctx);
        if (r)
                io->error = r;

        if (atomic_dec_and_test(&io->ctx.cc_pending))
                kcryptd_crypt_read_done(io);

        crypt_dec_pending(io);
}

static void kcryptd_async_done(struct crypto_async_request *async_req,
                               int error)
{
        struct dm_crypt_request *dmreq = async_req->data;
        struct convert_context *ctx = dmreq->ctx;
        struct dm_crypt_io *io = container_of(ctx, struct dm_crypt_io, ctx);
        struct crypt_config *cc = io->cc;

        /*
         * A request from crypto driver backlog is going to be processed now,
         * finish the completion and continue in crypt_convert().
         * (Callback will be called for the second time for this request.)
         */
        if (error == -EINPROGRESS) {
                complete(&ctx->restart);
                return;
        }

        if (!error && cc->iv_gen_ops && cc->iv_gen_ops->post)
                error = cc->iv_gen_ops->post(cc, org_iv_of_dmreq(cc, dmreq), dmreq);

        if (error == -EBADMSG) {
                char b[BDEVNAME_SIZE];
                DMERR_LIMIT("%s: INTEGRITY AEAD ERROR, sector %llu", bio_devname(ctx->bio_in, b),
                            (unsigned long long)le64_to_cpu(*org_sector_of_dmreq(cc, dmreq)));
                io->error = BLK_STS_PROTECTION;
        } else if (error < 0)
                io->error = BLK_STS_IOERR;

        crypt_free_req(cc, req_of_dmreq(cc, dmreq), io->base_bio);

        if (!atomic_dec_and_test(&ctx->cc_pending))
                return;

        if (bio_data_dir(io->base_bio) == READ)
                kcryptd_crypt_read_done(io);
        else
                kcryptd_crypt_write_io_submit(io, 1);
}

static void kcryptd_crypt(struct work_struct *work)
{
        struct dm_crypt_io *io = container_of(work, struct dm_crypt_io, work);

        if (bio_data_dir(io->base_bio) == READ)
                kcryptd_crypt_read_convert(io);
        else
                kcryptd_crypt_write_convert(io);
}

static void kcryptd_queue_crypt(struct dm_crypt_io *io)
{
        struct crypt_config *cc = io->cc;

        INIT_WORK(&io->work, kcryptd_crypt);
        queue_work(cc->crypt_queue, &io->work);
}

static void crypt_free_tfms_aead(struct crypt_config *cc)
{
        if (!cc->cipher_tfm.tfms_aead)
                return;

        if (cc->cipher_tfm.tfms_aead[0] && !IS_ERR(cc->cipher_tfm.tfms_aead[0])) {
                crypto_free_aead(cc->cipher_tfm.tfms_aead[0]);
                cc->cipher_tfm.tfms_aead[0] = NULL;
        }

        kfree(cc->cipher_tfm.tfms_aead);
        cc->cipher_tfm.tfms_aead = NULL;
}

static void crypt_free_tfms_skcipher(struct crypt_config *cc)
{
        unsigned i;

        if (!cc->cipher_tfm.tfms)
                return;

        for (i = 0; i < cc->tfms_count; i++)
                if (cc->cipher_tfm.tfms[i] && !IS_ERR(cc->cipher_tfm.tfms[i])) {
                        crypto_free_skcipher(cc->cipher_tfm.tfms[i]);
                        cc->cipher_tfm.tfms[i] = NULL;
                }

        kfree(cc->cipher_tfm.tfms);
        cc->cipher_tfm.tfms = NULL;
}

static void crypt_free_tfms(struct crypt_config *cc)
{
        if (crypt_integrity_aead(cc))
                crypt_free_tfms_aead(cc);
        else
                crypt_free_tfms_skcipher(cc);
}

static int crypt_alloc_tfms_skcipher(struct crypt_config *cc, char *ciphermode)
{
        unsigned i;
        int err;

        cc->cipher_tfm.tfms = kcalloc(cc->tfms_count,
                                      sizeof(struct crypto_skcipher *),
                                      GFP_KERNEL);
        if (!cc->cipher_tfm.tfms)
                return -ENOMEM;

        for (i = 0; i < cc->tfms_count; i++) {
                cc->cipher_tfm.tfms[i] = crypto_alloc_skcipher(ciphermode, 0, 0);
                if (IS_ERR(cc->cipher_tfm.tfms[i])) {
                        err = PTR_ERR(cc->cipher_tfm.tfms[i]);
                        crypt_free_tfms(cc);
                        return err;
                }
        }

        /*
         * dm-crypt performance can vary greatly depending on which crypto
         * algorithm implementation is used.  Help people debug performance
         * problems by logging the ->cra_driver_name.
         */
        DMDEBUG_LIMIT("%s using implementation \"%s\"", ciphermode,
               crypto_skcipher_alg(any_tfm(cc))->base.cra_driver_name);
        return 0;
}

static int crypt_alloc_tfms_aead(struct crypt_config *cc, char *ciphermode)
{
        int err;

        cc->cipher_tfm.tfms = kmalloc(sizeof(struct crypto_aead *), GFP_KERNEL);
        if (!cc->cipher_tfm.tfms)
                return -ENOMEM;

        cc->cipher_tfm.tfms_aead[0] = crypto_alloc_aead(ciphermode, 0, 0);
        if (IS_ERR(cc->cipher_tfm.tfms_aead[0])) {
                err = PTR_ERR(cc->cipher_tfm.tfms_aead[0]);
                crypt_free_tfms(cc);
                return err;
        }

        DMDEBUG_LIMIT("%s using implementation \"%s\"", ciphermode,
               crypto_aead_alg(any_tfm_aead(cc))->base.cra_driver_name);
        return 0;
}

static int crypt_alloc_tfms(struct crypt_config *cc, char *ciphermode)
{
        if (crypt_integrity_aead(cc))
                return crypt_alloc_tfms_aead(cc, ciphermode);
        else
                return crypt_alloc_tfms_skcipher(cc, ciphermode);
}

static unsigned crypt_subkey_size(struct crypt_config *cc)
{
        return (cc->key_size - cc->key_extra_size) >> ilog2(cc->tfms_count);
}

static unsigned crypt_authenckey_size(struct crypt_config *cc)
{
        return crypt_subkey_size(cc) + RTA_SPACE(sizeof(struct crypto_authenc_key_param));
}

/*
 * If AEAD is composed like authenc(hmac(sha256),xts(aes)),
 * the key must be for some reason in special format.
 * This funcion converts cc->key to this special format.
 */
static void crypt_copy_authenckey(char *p, const void *key,
                                  unsigned enckeylen, unsigned authkeylen)
{
        struct crypto_authenc_key_param *param;
        struct rtattr *rta;

        rta = (struct rtattr *)p;
        param = RTA_DATA(rta);
        param->enckeylen = cpu_to_be32(enckeylen);
        rta->rta_len = RTA_LENGTH(sizeof(*param));
        rta->rta_type = CRYPTO_AUTHENC_KEYA_PARAM;
        p += RTA_SPACE(sizeof(*param));
        memcpy(p, key + enckeylen, authkeylen);
        p += authkeylen;
        memcpy(p, key, enckeylen);
}

static int crypt_setkey(struct crypt_config *cc)
{
        unsigned subkey_size;
        int err = 0, i, r;

        /* Ignore extra keys (which are used for IV etc) */
        subkey_size = crypt_subkey_size(cc);

        if (crypt_integrity_hmac(cc)) {
                if (subkey_size < cc->key_mac_size)
                        return -EINVAL;

                crypt_copy_authenckey(cc->authenc_key, cc->key,
                                      subkey_size - cc->key_mac_size,
                                      cc->key_mac_size);
        }

        for (i = 0; i < cc->tfms_count; i++) {
                if (crypt_integrity_hmac(cc))
                        r = crypto_aead_setkey(cc->cipher_tfm.tfms_aead[i],
                                cc->authenc_key, crypt_authenckey_size(cc));
                else if (crypt_integrity_aead(cc))
                        r = crypto_aead_setkey(cc->cipher_tfm.tfms_aead[i],
                                               cc->key + (i * subkey_size),
                                               subkey_size);
                else
                        r = crypto_skcipher_setkey(cc->cipher_tfm.tfms[i],
                                                   cc->key + (i * subkey_size),
                                                   subkey_size);
                if (r)
                        err = r;
        }

        if (crypt_integrity_hmac(cc))
                memzero_explicit(cc->authenc_key, crypt_authenckey_size(cc));

        return err;
}

#ifdef CONFIG_KEYS

static bool contains_whitespace(const char *str)
{
        while (*str)
                if (isspace(*str++))
                        return true;
        return false;
}

static int crypt_set_keyring_key(struct crypt_config *cc, const char *key_string)
{
        char *new_key_string, *key_desc;
        int ret;
        struct key *key;
        const struct user_key_payload *ukp;

        /*
         * Reject key_string with whitespace. dm core currently lacks code for
         * proper whitespace escaping in arguments on DM_TABLE_STATUS path.
         */
        if (contains_whitespace(key_string)) {
                DMERR("whitespace chars not allowed in key string");
                return -EINVAL;
        }

        /* look for next ':' separating key_type from key_description */
        key_desc = strpbrk(key_string, ":");
        if (!key_desc || key_desc == key_string || !strlen(key_desc + 1))
                return -EINVAL;

        if (strncmp(key_string, "logon:", key_desc - key_string + 1) &&
            strncmp(key_string, "user:", key_desc - key_string + 1))
                return -EINVAL;

        new_key_string = kstrdup(key_string, GFP_KERNEL);
        if (!new_key_string)
                return -ENOMEM;

        key = request_key(key_string[0] == 'l' ? &key_type_logon : &key_type_user,
                          key_desc + 1, NULL);
        if (IS_ERR(key)) {
                kzfree(new_key_string);
                return PTR_ERR(key);
        }

        down_read(&key->sem);

        ukp = user_key_payload_locked(key);
        if (!ukp) {
                up_read(&key->sem);
                key_put(key);
                kzfree(new_key_string);
                return -EKEYREVOKED;
        }

        if (cc->key_size != ukp->datalen) {
                up_read(&key->sem);
                key_put(key);
                kzfree(new_key_string);
                return -EINVAL;
        }

        memcpy(cc->key, ukp->data, cc->key_size);

        up_read(&key->sem);
        key_put(key);

        /* clear the flag since following operations may invalidate previously valid key */
        clear_bit(DM_CRYPT_KEY_VALID, &cc->flags);

        ret = crypt_setkey(cc);

        if (!ret) {
                set_bit(DM_CRYPT_KEY_VALID, &cc->flags);
                kzfree(cc->key_string);
                cc->key_string = new_key_string;
        } else
                kzfree(new_key_string);

        return ret;
}

static int get_key_size(char **key_string)
{
        char *colon, dummy;
        int ret;

        if (*key_string[0] != ':')
                return strlen(*key_string) >> 1;

        /* look for next ':' in key string */
        colon = strpbrk(*key_string + 1, ":");
        if (!colon)
                return -EINVAL;

        if (sscanf(*key_string + 1, "%u%c", &ret, &dummy) != 2 || dummy != ':')
                return -EINVAL;

        *key_string = colon;

        /* remaining key string should be :<logon|user>:<key_desc> */

        return ret;
}

#else

static int crypt_set_keyring_key(struct crypt_config *cc, const char *key_string)
{
        return -EINVAL;
}

static int get_key_size(char **key_string)
{
        return (*key_string[0] == ':') ? -EINVAL : strlen(*key_string) >> 1;
}

#endif

static int crypt_set_key(struct crypt_config *cc, char *key)
{
        int r = -EINVAL;
        int key_string_len = strlen(key);

        /* Hyphen (which gives a key_size of zero) means there is no key. */
        if (!cc->key_size && strcmp(key, "-"))
                goto out;

        /* ':' means the key is in kernel keyring, short-circuit normal key processing */
        if (key[0] == ':') {
                r = crypt_set_keyring_key(cc, key + 1);
                goto out;
        }

        /* clear the flag since following operations may invalidate previously valid key */
        clear_bit(DM_CRYPT_KEY_VALID, &cc->flags);

        /* wipe references to any kernel keyring key */
        kzfree(cc->key_string);
        cc->key_string = NULL;

        /* Decode key from its hex representation. */
        if (cc->key_size && hex2bin(cc->key, key, cc->key_size) < 0)
                goto out;

        r = crypt_setkey(cc);
        if (!r)
                set_bit(DM_CRYPT_KEY_VALID, &cc->flags);

out:
        /* Hex key string not needed after here, so wipe it. */
        memset(key, '0', key_string_len);

        return r;
}

static int crypt_wipe_key(struct crypt_config *cc)
{
        int r;

        clear_bit(DM_CRYPT_KEY_VALID, &cc->flags);
        get_random_bytes(&cc->key, cc->key_size);

        /* Wipe IV private keys */
        if (cc->iv_gen_ops && cc->iv_gen_ops->wipe) {
                r = cc->iv_gen_ops->wipe(cc);
                if (r)
                        return r;
        }

        kzfree(cc->key_string);
        cc->key_string = NULL;
        r = crypt_setkey(cc);
        memset(&cc->key, 0, cc->key_size * sizeof(u8));

        return r;
}

static void crypt_calculate_pages_per_client(void)
{
        unsigned long pages = (totalram_pages() - totalhigh_pages()) * DM_CRYPT_MEMORY_PERCENT / 100;

        if (!dm_crypt_clients_n)
                return;

        pages /= dm_crypt_clients_n;
        if (pages < DM_CRYPT_MIN_PAGES_PER_CLIENT)
                pages = DM_CRYPT_MIN_PAGES_PER_CLIENT;
        dm_crypt_pages_per_client = pages;
}

static void *crypt_page_alloc(gfp_t gfp_mask, void *pool_data)
{
        struct crypt_config *cc = pool_data;
        struct page *page;

        if (unlikely(percpu_counter_compare(&cc->n_allocated_pages, dm_crypt_pages_per_client) >= 0) &&
            likely(gfp_mask & __GFP_NORETRY))
                return NULL;

        page = alloc_page(gfp_mask);
        if (likely(page != NULL))
                percpu_counter_add(&cc->n_allocated_pages, 1);

        return page;
}

static void crypt_page_free(void *page, void *pool_data)
{
        struct crypt_config *cc = pool_data;

        __free_page(page);
        percpu_counter_sub(&cc->n_allocated_pages, 1);
}

static void crypt_dtr(struct dm_target *ti)
{
        struct crypt_config *cc = ti->private;

        ti->private = NULL;

        if (!cc)
                return;

        if (cc->write_thread)
                kthread_stop(cc->write_thread);

        if (cc->io_queue)
                destroy_workqueue(cc->io_queue);
        if (cc->crypt_queue)
                destroy_workqueue(cc->crypt_queue);

        crypt_free_tfms(cc);

        bioset_exit(&cc->bs);

        mempool_exit(&cc->page_pool);
        mempool_exit(&cc->req_pool);
        mempool_exit(&cc->tag_pool);

        WARN_ON(percpu_counter_sum(&cc->n_allocated_pages) != 0);
        percpu_counter_destroy(&cc->n_allocated_pages);

        if (cc->iv_gen_ops && cc->iv_gen_ops->dtr)
                cc->iv_gen_ops->dtr(cc);

        if (cc->dev)
                dm_put_device(ti, cc->dev);

        kzfree(cc->cipher);
        kzfree(cc->cipher_string);
        kzfree(cc->key_string);
        kzfree(cc->cipher_auth);
        kzfree(cc->authenc_key);

        mutex_destroy(&cc->bio_alloc_lock);

        /* Must zero key material before freeing */
        kzfree(cc);

        spin_lock(&dm_crypt_clients_lock);
        WARN_ON(!dm_crypt_clients_n);
        dm_crypt_clients_n--;
        crypt_calculate_pages_per_client();
        spin_unlock(&dm_crypt_clients_lock);
}

static int crypt_ctr_ivmode(struct dm_target *ti, const char *ivmode)
{
        struct crypt_config *cc = ti->private;

        if (crypt_integrity_aead(cc))
                cc->iv_size = crypto_aead_ivsize(any_tfm_aead(cc));
        else
                cc->iv_size = crypto_skcipher_ivsize(any_tfm(cc));

        if (cc->iv_size)
                /* at least a 64 bit sector number should fit in our buffer */
                cc->iv_size = max(cc->iv_size,
                                  (unsigned int)(sizeof(u64) / sizeof(u8)));
        else if (ivmode) {
                DMWARN("Selected cipher does not support IVs");
                ivmode = NULL;
        }

        /* Choose ivmode, see comments at iv code. */
        if (ivmode == NULL)
                cc->iv_gen_ops = NULL;
        else if (strcmp(ivmode, "plain") == 0)
                cc->iv_gen_ops = &crypt_iv_plain_ops;
        else if (strcmp(ivmode, "plain64") == 0)
                cc->iv_gen_ops = &crypt_iv_plain64_ops;
        else if (strcmp(ivmode, "plain64be") == 0)
                cc->iv_gen_ops = &crypt_iv_plain64be_ops;
        else if (strcmp(ivmode, "essiv") == 0)
                cc->iv_gen_ops = &crypt_iv_essiv_ops;
        else if (strcmp(ivmode, "benbi") == 0)
                cc->iv_gen_ops = &crypt_iv_benbi_ops;
        else if (strcmp(ivmode, "null") == 0)
                cc->iv_gen_ops = &crypt_iv_null_ops;
        else if (strcmp(ivmode, "eboiv") == 0)
                cc->iv_gen_ops = &crypt_iv_eboiv_ops;
        else if (strcmp(ivmode, "lmk") == 0) {
                cc->iv_gen_ops = &crypt_iv_lmk_ops;
                /*
                 * Version 2 and 3 is recognised according
                 * to length of provided multi-key string.
                 * If present (version 3), last key is used as IV seed.
                 * All keys (including IV seed) are always the same size.
                 */
                if (cc->key_size % cc->key_parts) {
                        cc->key_parts++;
                        cc->key_extra_size = cc->key_size / cc->key_parts;
                }
        } else if (strcmp(ivmode, "tcw") == 0) {
                cc->iv_gen_ops = &crypt_iv_tcw_ops;
                cc->key_parts += 2; /* IV + whitening */
                cc->key_extra_size = cc->iv_size + TCW_WHITENING_SIZE;
        } else if (strcmp(ivmode, "random") == 0) {
                cc->iv_gen_ops = &crypt_iv_random_ops;
                /* Need storage space in integrity fields. */
                cc->integrity_iv_size = cc->iv_size;
        } else {
                ti->error = "Invalid IV mode";
                return -EINVAL;
        }

        return 0;
}

/*
 * Workaround to parse cipher algorithm from crypto API spec.
 * The cc->cipher is currently used only in ESSIV.
 * This should be probably done by crypto-api calls (once available...)
 */
static int crypt_ctr_blkdev_cipher(struct crypt_config *cc)
{
        const char *alg_name = NULL;
        char *start, *end;

        if (crypt_integrity_aead(cc)) {
                alg_name = crypto_tfm_alg_name(crypto_aead_tfm(any_tfm_aead(cc)));
                if (!alg_name)
                        return -EINVAL;
                if (crypt_integrity_hmac(cc)) {
                        alg_name = strchr(alg_name, ',');
                        if (!alg_name)
                                return -EINVAL;
                }
                alg_name++;
        } else {
                alg_name = crypto_tfm_alg_name(crypto_skcipher_tfm(any_tfm(cc)));
                if (!alg_name)
                        return -EINVAL;
        }

        start = strchr(alg_name, '(');
        end = strchr(alg_name, ')');

        if (!start && !end) {
                cc->cipher = kstrdup(alg_name, GFP_KERNEL);
                return cc->cipher ? 0 : -ENOMEM;
        }

        if (!start || !end || ++start >= end)
                return -EINVAL;

        cc->cipher = kzalloc(end - start + 1, GFP_KERNEL);
        if (!cc->cipher)
                return -ENOMEM;

        strncpy(cc->cipher, start, end - start);

        return 0;
}

/*
 * Workaround to parse HMAC algorithm from AEAD crypto API spec.
 * The HMAC is needed to calculate tag size (HMAC digest size).
 * This should be probably done by crypto-api calls (once available...)
 */
static int crypt_ctr_auth_cipher(struct crypt_config *cc, char *cipher_api)
{
        char *start, *end, *mac_alg = NULL;
        struct crypto_ahash *mac;

        if (!strstarts(cipher_api, "authenc("))
                return 0;

        start = strchr(cipher_api, '(');
        end = strchr(cipher_api, ',');
        if (!start || !end || ++start > end)
                return -EINVAL;

        mac_alg = kzalloc(end - start + 1, GFP_KERNEL);
        if (!mac_alg)
                return -ENOMEM;
        strncpy(mac_alg, start, end - start);

        mac = crypto_alloc_ahash(mac_alg, 0, 0);
        kfree(mac_alg);

        if (IS_ERR(mac))
                return PTR_ERR(mac);

        cc->key_mac_size = crypto_ahash_digestsize(mac);
        crypto_free_ahash(mac);

        cc->authenc_key = kmalloc(crypt_authenckey_size(cc), GFP_KERNEL);
        if (!cc->authenc_key)
                return -ENOMEM;

        return 0;
}

static int crypt_ctr_cipher_new(struct dm_target *ti, char *cipher_in, char *key,
                                char **ivmode, char **ivopts)
{
        struct crypt_config *cc = ti->private;
        char *tmp, *cipher_api;
        int ret = -EINVAL;

        cc->tfms_count = 1;

        /*
         * New format (capi: prefix)
         * capi:cipher_api_spec-iv:ivopts
         */
        tmp = &cipher_in[strlen("capi:")];

        /* Separate IV options if present, it can contain another '-' in hash name */
        *ivopts = strrchr(tmp, ':');
        if (*ivopts) {
                **ivopts = '\0';
                (*ivopts)++;
        }
        /* Parse IV mode */
        *ivmode = strrchr(tmp, '-');
        if (*ivmode) {
                **ivmode = '\0';
                (*ivmode)++;
        }
        /* The rest is crypto API spec */
        cipher_api = tmp;

        if (*ivmode && !strcmp(*ivmode, "lmk"))
                cc->tfms_count = 64;

        cc->key_parts = cc->tfms_count;

        /* Allocate cipher */
        ret = crypt_alloc_tfms(cc, cipher_api);
        if (ret < 0) {
                ti->error = "Error allocating crypto tfm";
                return ret;
        }

        /* Alloc AEAD, can be used only in new format. */
        if (crypt_integrity_aead(cc)) {
                ret = crypt_ctr_auth_cipher(cc, cipher_api);
                if (ret < 0) {
                        ti->error = "Invalid AEAD cipher spec";
                        return -ENOMEM;
                }
                cc->iv_size = crypto_aead_ivsize(any_tfm_aead(cc));
        } else
                cc->iv_size = crypto_skcipher_ivsize(any_tfm(cc));

        ret = crypt_ctr_blkdev_cipher(cc);
        if (ret < 0) {
                ti->error = "Cannot allocate cipher string";
                return -ENOMEM;
        }

        return 0;
}

static int crypt_ctr_cipher_old(struct dm_target *ti, char *cipher_in, char *key,
                                char **ivmode, char **ivopts)
{
        struct crypt_config *cc = ti->private;
        char *tmp, *cipher, *chainmode, *keycount;
        char *cipher_api = NULL;
        int ret = -EINVAL;
        char dummy;

        if (strchr(cipher_in, '(') || crypt_integrity_aead(cc)) {
                ti->error = "Bad cipher specification";
                return -EINVAL;
        }

        /*
         * Legacy dm-crypt cipher specification
         * cipher[:keycount]-mode-iv:ivopts
         */
        tmp = cipher_in;
        keycount = strsep(&tmp, "-");
        cipher = strsep(&keycount, ":");

        if (!keycount)
                cc->tfms_count = 1;
        else if (sscanf(keycount, "%u%c", &cc->tfms_count, &dummy) != 1 ||
                 !is_power_of_2(cc->tfms_count)) {
                ti->error = "Bad cipher key count specification";
                return -EINVAL;
        }
        cc->key_parts = cc->tfms_count;

        cc->cipher = kstrdup(cipher, GFP_KERNEL);
        if (!cc->cipher)
                goto bad_mem;

        chainmode = strsep(&tmp, "-");
        *ivmode = strsep(&tmp, ":");
        *ivopts = tmp;

        /*
         * For compatibility with the original dm-crypt mapping format, if
         * only the cipher name is supplied, use cbc-plain.
         */
        if (!chainmode || (!strcmp(chainmode, "plain") && !*ivmode)) {
                chainmode = "cbc";
                *ivmode = "plain";
        }

        if (strcmp(chainmode, "ecb") && !*ivmode) {
                ti->error = "IV mechanism required";
                return -EINVAL;
        }

        cipher_api = kmalloc(CRYPTO_MAX_ALG_NAME, GFP_KERNEL);
        if (!cipher_api)
                goto bad_mem;

        ret = snprintf(cipher_api, CRYPTO_MAX_ALG_NAME,
                       "%s(%s)", chainmode, cipher);
        if (ret < 0) {
                kfree(cipher_api);
                goto bad_mem;
        }

        /* Allocate cipher */
        ret = crypt_alloc_tfms(cc, cipher_api);
        if (ret < 0) {
                ti->error = "Error allocating crypto tfm";
                kfree(cipher_api);
                return ret;
        }
        kfree(cipher_api);

        return 0;
bad_mem:
        ti->error = "Cannot allocate cipher strings";
        return -ENOMEM;
}

static int crypt_ctr_cipher(struct dm_target *ti, char *cipher_in, char *key)
{
        struct crypt_config *cc = ti->private;
        char *ivmode = NULL, *ivopts = NULL;
        int ret;

        cc->cipher_string = kstrdup(cipher_in, GFP_KERNEL);
        if (!cc->cipher_string) {
                ti->error = "Cannot allocate cipher strings";
                return -ENOMEM;
        }

        if (strstarts(cipher_in, "capi:"))
                ret = crypt_ctr_cipher_new(ti, cipher_in, key, &ivmode, &ivopts);
        else
                ret = crypt_ctr_cipher_old(ti, cipher_in, key, &ivmode, &ivopts);
        if (ret)
                return ret;

        /* Initialize IV */
        ret = crypt_ctr_ivmode(ti, ivmode);
        if (ret < 0)
                return ret;

        /* Initialize and set key */
        ret = crypt_set_key(cc, key);
        if (ret < 0) {
                ti->error = "Error decoding and setting key";
                return ret;
        }

        /* Allocate IV */
        if (cc->iv_gen_ops && cc->iv_gen_ops->ctr) {
                ret = cc->iv_gen_ops->ctr(cc, ti, ivopts);
                if (ret < 0) {
                        ti->error = "Error creating IV";
                        return ret;
                }
        }

        /* Initialize IV (set keys for ESSIV etc) */
        if (cc->iv_gen_ops && cc->iv_gen_ops->init) {
                ret = cc->iv_gen_ops->init(cc);
                if (ret < 0) {
                        ti->error = "Error initialising IV";
                        return ret;
                }
        }

        /* wipe the kernel key payload copy */
        if (cc->key_string)
                memset(cc->key, 0, cc->key_size * sizeof(u8));

        return ret;
}

static int crypt_ctr_optional(struct dm_target *ti, unsigned int argc, char **argv)
{
        struct crypt_config *cc = ti->private;
        struct dm_arg_set as;
        static const struct dm_arg _args[] = {
                {0, 6, "Invalid number of feature args"},
        };
        unsigned int opt_params, val;
        const char *opt_string, *sval;
        char dummy;
        int ret;

        /* Optional parameters */
        as.argc = argc;
        as.argv = argv;

        ret = dm_read_arg_group(_args, &as, &opt_params, &ti->error);
        if (ret)
                return ret;

        while (opt_params--) {
                opt_string = dm_shift_arg(&as);
                if (!opt_string) {
                        ti->error = "Not enough feature arguments";
                        return -EINVAL;
                }

                if (!strcasecmp(opt_string, "allow_discards"))
                        ti->num_discard_bios = 1;

                else if (!strcasecmp(opt_string, "same_cpu_crypt"))
                        set_bit(DM_CRYPT_SAME_CPU, &cc->flags);

                else if (!strcasecmp(opt_string, "submit_from_crypt_cpus"))
                        set_bit(DM_CRYPT_NO_OFFLOAD, &cc->flags);
                else if (sscanf(opt_string, "integrity:%u:", &val) == 1) {
                        if (val == 0 || val > MAX_TAG_SIZE) {
                                ti->error = "Invalid integrity arguments";
                                return -EINVAL;
                        }
                        cc->on_disk_tag_size = val;
                        sval = strchr(opt_string + strlen("integrity:"), ':') + 1;
                        if (!strcasecmp(sval, "aead")) {
                                set_bit(CRYPT_MODE_INTEGRITY_AEAD, &cc->cipher_flags);
                        } else  if (strcasecmp(sval, "none")) {
                                ti->error = "Unknown integrity profile";
                                return -EINVAL;
                        }

                        cc->cipher_auth = kstrdup(sval, GFP_KERNEL);
                        if (!cc->cipher_auth)
                                return -ENOMEM;
                } else if (sscanf(opt_string, "sector_size:%hu%c", &cc->sector_size, &dummy) == 1) {
                        if (cc->sector_size < (1 << SECTOR_SHIFT) ||
                            cc->sector_size > 4096 ||
                            (cc->sector_size & (cc->sector_size - 1))) {
                                ti->error = "Invalid feature value for sector_size";
                                return -EINVAL;
                        }
                        if (ti->len & ((cc->sector_size >> SECTOR_SHIFT) - 1)) {
                                ti->error = "Device size is not multiple of sector_size feature";
                                return -EINVAL;
                        }
                        cc->sector_shift = __ffs(cc->sector_size) - SECTOR_SHIFT;
                } else if (!strcasecmp(opt_string, "iv_large_sectors"))
                        set_bit(CRYPT_IV_LARGE_SECTORS, &cc->cipher_flags);
                else {
                        ti->error = "Invalid feature arguments";
                        return -EINVAL;
                }
        }

        return 0;
}

/*
 * Construct an encryption mapping:
 * <cipher> [<key>|:<key_size>:<user|logon>:<key_description>] <iv_offset> <dev_path> <start>
 */
static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
{
        struct crypt_config *cc;
        const char *devname = dm_table_device_name(ti->table);
        int key_size;
        unsigned int align_mask;
        unsigned long long tmpll;
        int ret;
        size_t iv_size_padding, additional_req_size;
        char dummy;

        if (argc < 5) {
                ti->error = "Not enough arguments";
                return -EINVAL;
        }

        key_size = get_key_size(&argv[1]);
        if (key_size < 0) {
                ti->error = "Cannot parse key size";
                return -EINVAL;
        }

        cc = kzalloc(struct_size(cc, key, key_size), GFP_KERNEL);
        if (!cc) {
                ti->error = "Cannot allocate encryption context";
                return -ENOMEM;
        }
        cc->key_size = key_size;
        cc->sector_size = (1 << SECTOR_SHIFT);
        cc->sector_shift = 0;

        ti->private = cc;

        spin_lock(&dm_crypt_clients_lock);
        dm_crypt_clients_n++;
        crypt_calculate_pages_per_client();
        spin_unlock(&dm_crypt_clients_lock);

        ret = percpu_counter_init(&cc->n_allocated_pages, 0, GFP_KERNEL);
        if (ret < 0)
                goto bad;

        /* Optional parameters need to be read before cipher constructor */
        if (argc > 5) {
                ret = crypt_ctr_optional(ti, argc - 5, &argv[5]);
                if (ret)
                        goto bad;
        }

        ret = crypt_ctr_cipher(ti, argv[0], argv[1]);
        if (ret < 0)
                goto bad;

        if (crypt_integrity_aead(cc)) {
                cc->dmreq_start = sizeof(struct aead_request);
                cc->dmreq_start += crypto_aead_reqsize(any_tfm_aead(cc));
                align_mask = crypto_aead_alignmask(any_tfm_aead(cc));
        } else {
                cc->dmreq_start = sizeof(struct skcipher_request);
                cc->dmreq_start += crypto_skcipher_reqsize(any_tfm(cc));
                align_mask = crypto_skcipher_alignmask(any_tfm(cc));
        }
        cc->dmreq_start = ALIGN(cc->dmreq_start, __alignof__(struct dm_crypt_request));

        if (align_mask < CRYPTO_MINALIGN) {
                /* Allocate the padding exactly */
                iv_size_padding = -(cc->dmreq_start + sizeof(struct dm_crypt_request))
                                & align_mask;
        } else {
                /*
                 * If the cipher requires greater alignment than kmalloc
                 * alignment, we don't know the exact position of the
                 * initialization vector. We must assume worst case.
                 */
                iv_size_padding = align_mask;
        }

        /*  ...| IV + padding | original IV | original sec. number | bio tag offset | */
        additional_req_size = sizeof(struct dm_crypt_request) +
                iv_size_padding + cc->iv_size +
                cc->iv_size +
                sizeof(uint64_t) +
                sizeof(unsigned int);

        ret = mempool_init_kmalloc_pool(&cc->req_pool, MIN_IOS, cc->dmreq_start + additional_req_size);
        if (ret) {
                ti->error = "Cannot allocate crypt request mempool";
                goto bad;
        }

        cc->per_bio_data_size = ti->per_io_data_size =
                ALIGN(sizeof(struct dm_crypt_io) + cc->dmreq_start + additional_req_size,
                      ARCH_KMALLOC_MINALIGN);

        ret = mempool_init(&cc->page_pool, BIO_MAX_PAGES, crypt_page_alloc, crypt_page_free, cc);
        if (ret) {
                ti->error = "Cannot allocate page mempool";
                goto bad;
        }

        ret = bioset_init(&cc->bs, MIN_IOS, 0, BIOSET_NEED_BVECS);
        if (ret) {
                ti->error = "Cannot allocate crypt bioset";
                goto bad;
        }

        mutex_init(&cc->bio_alloc_lock);

        ret = -EINVAL;
        if ((sscanf(argv[2], "%llu%c", &tmpll, &dummy) != 1) ||
            (tmpll & ((cc->sector_size >> SECTOR_SHIFT) - 1))) {
                ti->error = "Invalid iv_offset sector";
                goto bad;
        }
        cc->iv_offset = tmpll;

        ret = dm_get_device(ti, argv[3], dm_table_get_mode(ti->table), &cc->dev);
        if (ret) {
                ti->error = "Device lookup failed";
                goto bad;
        }

        ret = -EINVAL;
        if (sscanf(argv[4], "%llu%c", &tmpll, &dummy) != 1 || tmpll != (sector_t)tmpll) {
                ti->error = "Invalid device sector";
                goto bad;
        }
        cc->start = tmpll;

        if (crypt_integrity_aead(cc) || cc->integrity_iv_size) {
                ret = crypt_integrity_ctr(cc, ti);
                if (ret)
                        goto bad;

                cc->tag_pool_max_sectors = POOL_ENTRY_SIZE / cc->on_disk_tag_size;
                if (!cc->tag_pool_max_sectors)
                        cc->tag_pool_max_sectors = 1;

                ret = mempool_init_kmalloc_pool(&cc->tag_pool, MIN_IOS,
                        cc->tag_pool_max_sectors * cc->on_disk_tag_size);
                if (ret) {
                        ti->error = "Cannot allocate integrity tags mempool";
                        goto bad;
                }

                cc->tag_pool_max_sectors <<= cc->sector_shift;
        }

        ret = -ENOMEM;
        cc->io_queue = alloc_workqueue("kcryptd_io/%s",
                                       WQ_HIGHPRI | WQ_CPU_INTENSIVE | WQ_MEM_RECLAIM,
                                       1, devname);
        if (!cc->io_queue) {
                ti->error = "Couldn't create kcryptd io queue";
                goto bad;
        }

        if (test_bit(DM_CRYPT_SAME_CPU, &cc->flags))
                cc->crypt_queue = alloc_workqueue("kcryptd/%s",
                                                  WQ_HIGHPRI | WQ_CPU_INTENSIVE | WQ_MEM_RECLAIM,
                                                  1, devname);
        else
                cc->crypt_queue = alloc_workqueue("kcryptd/%s",
                                                  WQ_HIGHPRI | WQ_CPU_INTENSIVE | WQ_MEM_RECLAIM | WQ_UNBOUND,
                                                  num_online_cpus(), devname);
        if (!cc->crypt_queue) {
                ti->error = "Couldn't create kcryptd queue";
                goto bad;
        }

        spin_lock_init(&cc->write_thread_lock);
        cc->write_tree = RB_ROOT;

        cc->write_thread = kthread_create(dmcrypt_write, cc, "dmcrypt_write/%s", devname);
        if (IS_ERR(cc->write_thread)) {
                ret = PTR_ERR(cc->write_thread);
                cc->write_thread = NULL;
                ti->error = "Couldn't spawn write thread";
                goto bad;
        }
        wake_up_process(cc->write_thread);

        ti->num_flush_bios = 1;

        return 0;

bad:
        crypt_dtr(ti);
        return ret;
}

static int crypt_map(struct dm_target *ti, struct bio *bio)
{
        struct dm_crypt_io *io;
        struct crypt_config *cc = ti->private;

        /*
         * If bio is REQ_PREFLUSH or REQ_OP_DISCARD, just bypass crypt queues.
         * - for REQ_PREFLUSH device-mapper core ensures that no IO is in-flight
         * - for REQ_OP_DISCARD caller must use flush if IO ordering matters
         */
        if (unlikely(bio->bi_opf & REQ_PREFLUSH ||
            bio_op(bio) == REQ_OP_DISCARD)) {
                bio_set_dev(bio, cc->dev->bdev);
                if (bio_sectors(bio))
                        bio->bi_iter.bi_sector = cc->start +
                                dm_target_offset(ti, bio->bi_iter.bi_sector);
                return DM_MAPIO_REMAPPED;
        }

        /*
         * Check if bio is too large, split as needed.
         */
        if (unlikely(bio->bi_iter.bi_size > (BIO_MAX_PAGES << PAGE_SHIFT)) &&
            (bio_data_dir(bio) == WRITE || cc->on_disk_tag_size))
                dm_accept_partial_bio(bio, ((BIO_MAX_PAGES << PAGE_SHIFT) >> SECTOR_SHIFT));

        /*
         * Ensure that bio is a multiple of internal sector encryption size
         * and is aligned to this size as defined in IO hints.
         */
        if (unlikely((bio->bi_iter.bi_sector & ((cc->sector_size >> SECTOR_SHIFT) - 1)) != 0))
                return DM_MAPIO_KILL;

        if (unlikely(bio->bi_iter.bi_size & (cc->sector_size - 1)))
                return DM_MAPIO_KILL;

        io = dm_per_bio_data(bio, cc->per_bio_data_size);
        crypt_io_init(io, cc, bio, dm_target_offset(ti, bio->bi_iter.bi_sector));

        if (cc->on_disk_tag_size) {
                unsigned tag_len = cc->on_disk_tag_size * (bio_sectors(bio) >> cc->sector_shift);

                if (unlikely(tag_len > KMALLOC_MAX_SIZE) ||
                    unlikely(!(io->integrity_metadata = kmalloc(tag_len,
                                GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN)))) {