1 files changed, 977 insertions, 0 deletions

diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
new file mode 100644
index 000000000000..77619a56e2bf
--- /dev/null
+++ b/drivers/md/dm-crypt.c
@@ -0,0 +1,977 @@
+/*
+ * Copyright (C) 2003 Christophe Saout <christophe@saout.de>
+ * Copyright (C) 2004 Clemens Fruhwirth <clemens@endorphin.org>
+ *
+ * This file is released under the GPL.
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/kernel.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 <asm/atomic.h>
+#include <asm/scatterlist.h>
+#include <asm/page.h>
+
+#include "dm.h"
+
+#define PFX     "crypt: "
+
+/*
+ * per bio private data
+ */
+struct crypt_io {
+        struct dm_target *target;
+        struct bio *bio;
+        struct bio *first_clone;
+        struct work_struct work;
+        atomic_t pending;
+        int error;
+};
+
+/*
+ * context holding the current state of a multi-part conversion
+ */
+struct convert_context {
+        struct bio *bio_in;
+        struct bio *bio_out;
+        unsigned int offset_in;
+        unsigned int offset_out;
+        unsigned int idx_in;
+        unsigned int idx_out;
+        sector_t sector;
+        int write;
+};
+
+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);
+        const char *(*status)(struct crypt_config *cc);
+        int (*generator)(struct crypt_config *cc, u8 *iv, sector_t sector);
+};
+
+/*
+ * Crypt: maps a linear range of a block device
+ * and encrypts / decrypts at the same time.
+ */
+struct crypt_config {
+        struct dm_dev *dev;
+        sector_t start;
+
+        /*
+         * pool for per bio private data and
+         * for encryption buffer pages
+         */
+        mempool_t *io_pool;
+        mempool_t *page_pool;
+
+        /*
+         * crypto related data
+         */
+        struct crypt_iv_operations *iv_gen_ops;
+        char *iv_mode;
+        void *iv_gen_private;
+        sector_t iv_offset;
+        unsigned int iv_size;
+
+        struct crypto_tfm *tfm;
+        unsigned int key_size;
+        u8 key[0];
+};
+
+#define MIN_IOS        256
+#define MIN_POOL_PAGES 32
+#define MIN_BIO_PAGES  8
+
+static kmem_cache_t *_crypt_io_pool;
+
+/*
+ * Mempool alloc and free functions for the page
+ */
+static void *mempool_alloc_page(unsigned int __nocast gfp_mask, void *data)
+{
+        return alloc_page(gfp_mask);
+}
+
+static void mempool_free_page(void *page, void *data)
+{
+        __free_page(page);
+}
+
+
+/*
+ * Different IV generation algorithms:
+ *
+ * plain: the initial vector is the 32-bit low-endian version of the sector
+ *        number, padded with zeros if neccessary.
+ *
+ * ess_iv: "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.
+ *
+ * plumb: unimplemented, see:
+ * http://article.gmane.org/gmane.linux.kernel.device-mapper.dm-crypt/454
+ */
+
+static int crypt_iv_plain_gen(struct crypt_config *cc, u8 *iv, sector_t sector)
+{
+        memset(iv, 0, cc->iv_size);
+        *(u32 *)iv = cpu_to_le32(sector & 0xffffffff);
+
+        return 0;
+}
+
+static int crypt_iv_essiv_ctr(struct crypt_config *cc, struct dm_target *ti,
+                              const char *opts)
+{
+        struct crypto_tfm *essiv_tfm;
+        struct crypto_tfm *hash_tfm;
+        struct scatterlist sg;
+        unsigned int saltsize;
+        u8 *salt;
+
+        if (opts == NULL) {
+                ti->error = PFX "Digest algorithm missing for ESSIV mode";
+                return -EINVAL;
+        }
+
+        /* Hash the cipher key with the given hash algorithm */
+        hash_tfm = crypto_alloc_tfm(opts, 0);
+        if (hash_tfm == NULL) {
+                ti->error = PFX "Error initializing ESSIV hash";
+                return -EINVAL;
+        }
+
+        if (crypto_tfm_alg_type(hash_tfm) != CRYPTO_ALG_TYPE_DIGEST) {
+                ti->error = PFX "Expected digest algorithm for ESSIV hash";
+                crypto_free_tfm(hash_tfm);
+                return -EINVAL;
+        }
+
+        saltsize = crypto_tfm_alg_digestsize(hash_tfm);
+        salt = kmalloc(saltsize, GFP_KERNEL);
+        if (salt == NULL) {
+                ti->error = PFX "Error kmallocing salt storage in ESSIV";
+                crypto_free_tfm(hash_tfm);
+                return -ENOMEM;
+        }
+
+        sg.page = virt_to_page(cc->key);
+        sg.offset = offset_in_page(cc->key);
+        sg.length = cc->key_size;
+        crypto_digest_digest(hash_tfm, &sg, 1, salt);
+        crypto_free_tfm(hash_tfm);
+
+        /* Setup the essiv_tfm with the given salt */
+        essiv_tfm = crypto_alloc_tfm(crypto_tfm_alg_name(cc->tfm),
+                                     CRYPTO_TFM_MODE_ECB);
+        if (essiv_tfm == NULL) {
+                ti->error = PFX "Error allocating crypto tfm for ESSIV";
+                kfree(salt);
+                return -EINVAL;
+        }
+        if (crypto_tfm_alg_blocksize(essiv_tfm)
+            != crypto_tfm_alg_ivsize(cc->tfm)) {
+                ti->error = PFX "Block size of ESSIV cipher does "
+                                "not match IV size of block cipher";
+                crypto_free_tfm(essiv_tfm);
+                kfree(salt);
+                return -EINVAL;
+        }
+        if (crypto_cipher_setkey(essiv_tfm, salt, saltsize) < 0) {
+                ti->error = PFX "Failed to set key for ESSIV cipher";
+                crypto_free_tfm(essiv_tfm);
+                kfree(salt);
+                return -EINVAL;
+        }
+        kfree(salt);
+
+        cc->iv_gen_private = (void *)essiv_tfm;
+        return 0;
+}
+
+static void crypt_iv_essiv_dtr(struct crypt_config *cc)
+{
+        crypto_free_tfm((struct crypto_tfm *)cc->iv_gen_private);
+        cc->iv_gen_private = NULL;
+}
+
+static int crypt_iv_essiv_gen(struct crypt_config *cc, u8 *iv, sector_t sector)
+{
+        struct scatterlist sg = { NULL, };
+
+        memset(iv, 0, cc->iv_size);
+        *(u64 *)iv = cpu_to_le64(sector);
+
+        sg.page = virt_to_page(iv);
+        sg.offset = offset_in_page(iv);
+        sg.length = cc->iv_size;
+        crypto_cipher_encrypt((struct crypto_tfm *)cc->iv_gen_private,
+                              &sg, &sg, cc->iv_size);
+
+        return 0;
+}
+
+static struct crypt_iv_operations crypt_iv_plain_ops = {
+        .generator = crypt_iv_plain_gen
+};
+
+static struct crypt_iv_operations crypt_iv_essiv_ops = {
+        .ctr       = crypt_iv_essiv_ctr,
+        .dtr       = crypt_iv_essiv_dtr,
+        .generator = crypt_iv_essiv_gen
+};
+
+
+static inline int
+crypt_convert_scatterlist(struct crypt_config *cc, struct scatterlist *out,
+                          struct scatterlist *in, unsigned int length,
+                          int write, sector_t sector)
+{
+        u8 iv[cc->iv_size];
+        int r;
+
+        if (cc->iv_gen_ops) {
+                r = cc->iv_gen_ops->generator(cc, iv, sector);
+                if (r < 0)
+                        return r;
+
+                if (write)
+                        r = crypto_cipher_encrypt_iv(cc->tfm, out, in, length, iv);
+                else
+                        r = crypto_cipher_decrypt_iv(cc->tfm, out, in, length, iv);
+        } else {
+                if (write)
+                        r = crypto_cipher_encrypt(cc->tfm, out, in, length);
+                else
+                        r = crypto_cipher_decrypt(cc->tfm, out, in, length);
+        }
+
+        return r;
+}
+
+static void
+crypt_convert_init(struct crypt_config *cc, struct convert_context *ctx,
+                   struct bio *bio_out, struct bio *bio_in,
+                   sector_t sector, int write)
+{
+        ctx->bio_in = bio_in;
+        ctx->bio_out = bio_out;
+        ctx->offset_in = 0;
+        ctx->offset_out = 0;
+        ctx->idx_in = bio_in ? bio_in->bi_idx : 0;
+        ctx->idx_out = bio_out ? bio_out->bi_idx : 0;
+        ctx->sector = sector + cc->iv_offset;
+        ctx->write = write;
+}
+
+/*
+ * Encrypt / decrypt data from one bio to another one (can be the same one)
+ */
+static int crypt_convert(struct crypt_config *cc,
+                         struct convert_context *ctx)
+{
+        int r = 0;
+
+        while(ctx->idx_in < ctx->bio_in->bi_vcnt &&
+              ctx->idx_out < ctx->bio_out->bi_vcnt) {
+                struct bio_vec *bv_in = bio_iovec_idx(ctx->bio_in, ctx->idx_in);
+                struct bio_vec *bv_out = bio_iovec_idx(ctx->bio_out, ctx->idx_out);
+                struct scatterlist sg_in = {
+                        .page = bv_in->bv_page,
+                        .offset = bv_in->bv_offset + ctx->offset_in,
+                        .length = 1 << SECTOR_SHIFT
+                };
+                struct scatterlist sg_out = {
+                        .page = bv_out->bv_page,
+                        .offset = bv_out->bv_offset + ctx->offset_out,
+                        .length = 1 << SECTOR_SHIFT
+                };
+
+                ctx->offset_in += sg_in.length;
+                if (ctx->offset_in >= bv_in->bv_len) {
+                        ctx->offset_in = 0;
+                        ctx->idx_in++;
+                }
+
+                ctx->offset_out += sg_out.length;
+                if (ctx->offset_out >= bv_out->bv_len) {
+                        ctx->offset_out = 0;
+                        ctx->idx_out++;
+                }
+
+                r = crypt_convert_scatterlist(cc, &sg_out, &sg_in, sg_in.length,
+                                              ctx->write, ctx->sector);
+                if (r < 0)
+                        break;
+
+                ctx->sector++;
+        }
+
+        return r;
+}
+
+/*
+ * Generate a new unfragmented bio with the given size
+ * This should never violate the device limitations
+ * May return a smaller bio when running out of pages
+ */
+static struct bio *
+crypt_alloc_buffer(struct crypt_config *cc, unsigned int size,
+                   struct bio *base_bio, unsigned int *bio_vec_idx)
+{
+        struct bio *bio;
+        unsigned int nr_iovecs = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
+        int gfp_mask = GFP_NOIO | __GFP_HIGHMEM;
+        unsigned long flags = current->flags;
+        unsigned int i;
+
+        /*
+         * Tell VM to act less aggressively and fail earlier.
+         * This is not necessary but increases throughput.
+         * FIXME: Is this really intelligent?
+         */
+        current->flags &= ~PF_MEMALLOC;
+
+        if (base_bio)
+                bio = bio_clone(base_bio, GFP_NOIO);
+        else
+                bio = bio_alloc(GFP_NOIO, nr_iovecs);
+        if (!bio) {
+                if (flags & PF_MEMALLOC)
+                        current->flags |= PF_MEMALLOC;
+                return NULL;
+        }
+
+        /* if the last bio was not complete, continue where that one ended */
+        bio->bi_idx = *bio_vec_idx;
+        bio->bi_vcnt = *bio_vec_idx;
+        bio->bi_size = 0;
+        bio->bi_flags &= ~(1 << BIO_SEG_VALID);
+
+        /* bio->bi_idx pages have already been allocated */
+        size -= bio->bi_idx * PAGE_SIZE;
+
+        for(i = bio->bi_idx; i < nr_iovecs; i++) {
+                struct bio_vec *bv = bio_iovec_idx(bio, i);
+
+                bv->bv_page = mempool_alloc(cc->page_pool, gfp_mask);
+                if (!bv->bv_page)
+                        break;
+
+                /*
+                 * if additional pages cannot be allocated without waiting,
+                 * return a partially allocated bio, the caller will then try
+                 * to allocate additional bios while submitting this partial bio
+                 */
+                if ((i - bio->bi_idx) == (MIN_BIO_PAGES - 1))
+                        gfp_mask = (gfp_mask | __GFP_NOWARN) & ~__GFP_WAIT;
+
+                bv->bv_offset = 0;
+                if (size > PAGE_SIZE)
+                        bv->bv_len = PAGE_SIZE;
+                else
+                        bv->bv_len = size;
+
+                bio->bi_size += bv->bv_len;
+                bio->bi_vcnt++;
+                size -= bv->bv_len;
+        }
+
+        if (flags & PF_MEMALLOC)
+                current->flags |= PF_MEMALLOC;
+
+        if (!bio->bi_size) {
+                bio_put(bio);
+                return NULL;
+        }
+
+        /*
+         * Remember the last bio_vec allocated to be able
+         * to correctly continue after the splitting.
+         */
+        *bio_vec_idx = bio->bi_vcnt;
+
+        return bio;
+}
+
+static void crypt_free_buffer_pages(struct crypt_config *cc,
+                                    struct bio *bio, unsigned int bytes)
+{
+        unsigned int i, start, end;
+        struct bio_vec *bv;
+
+        /*
+         * This is ugly, but Jens Axboe thinks that using bi_idx in the
+         * endio function is too dangerous at the moment, so I calculate the
+         * correct position using bi_vcnt and bi_size.
+         * The bv_offset and bv_len fields might already be modified but we
+         * know that we always allocated whole pages.
+         * A fix to the bi_idx issue in the kernel is in the works, so
+         * we will hopefully be able to revert to the cleaner solution soon.
+         */
+        i = bio->bi_vcnt - 1;
+        bv = bio_iovec_idx(bio, i);
+        end = (i << PAGE_SHIFT) + (bv->bv_offset + bv->bv_len) - bio->bi_size;
+        start = end - bytes;
+
+        start >>= PAGE_SHIFT;
+        if (!bio->bi_size)
+                end = bio->bi_vcnt;
+        else
+                end >>= PAGE_SHIFT;
+
+        for(i = start; i < end; i++) {
+                bv = bio_iovec_idx(bio, i);
+                BUG_ON(!bv->bv_page);
+                mempool_free(bv->bv_page, cc->page_pool);
+                bv->bv_page = NULL;
+        }
+}
+
+/*
+ * One of the bios was finished. Check for completion of
+ * the whole request and correctly clean up the buffer.
+ */
+static void dec_pending(struct crypt_io *io, int error)
+{
+        struct crypt_config *cc = (struct crypt_config *) io->target->private;
+
+        if (error < 0)
+                io->error = error;
+
+        if (!atomic_dec_and_test(&io->pending))
+                return;
+
+        if (io->first_clone)
+                bio_put(io->first_clone);
+
+        bio_endio(io->bio, io->bio->bi_size, io->error);
+
+        mempool_free(io, cc->io_pool);
+}
+
+/*
+ * kcryptd:
+ *
+ * Needed because it would be very unwise to do decryption in an
+ * interrupt context, so bios returning from read requests get
+ * queued here.
+ */
+static struct workqueue_struct *_kcryptd_workqueue;
+
+static void kcryptd_do_work(void *data)
+{
+        struct crypt_io *io = (struct crypt_io *) data;
+        struct crypt_config *cc = (struct crypt_config *) io->target->private;
+        struct convert_context ctx;
+        int r;
+
+        crypt_convert_init(cc, &ctx, io->bio, io->bio,
+                           io->bio->bi_sector - io->target->begin, 0);
+        r = crypt_convert(cc, &ctx);
+
+        dec_pending(io, r);
+}
+
+static void kcryptd_queue_io(struct crypt_io *io)
+{
+        INIT_WORK(&io->work, kcryptd_do_work, io);
+        queue_work(_kcryptd_workqueue, &io->work);
+}
+
+/*
+ * Decode key from its hex representation
+ */
+static int crypt_decode_key(u8 *key, char *hex, unsigned int size)
+{
+        char buffer[3];
+        char *endp;
+        unsigned int i;
+
+        buffer[2] = '\0';
+
+        for(i = 0; i < size; i++) {
+                buffer[0] = *hex++;
+                buffer[1] = *hex++;
+
+                key[i] = (u8)simple_strtoul(buffer, &endp, 16);
+
+                if (endp != &buffer[2])
+                        return -EINVAL;
+        }
+
+        if (*hex != '\0')
+                return -EINVAL;
+
+        return 0;
+}
+
+/*
+ * Encode key into its hex representation
+ */
+static void crypt_encode_key(char *hex, u8 *key, unsigned int size)
+{
+        unsigned int i;
+
+        for(i = 0; i < size; i++) {
+                sprintf(hex, "%02x", *key);
+                hex += 2;
+                key++;
+        }
+}
+
+/*
+ * Construct an encryption mapping:
+ * <cipher> <key> <iv_offset> <dev_path> <start>
+ */
+static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
+{
+        struct crypt_config *cc;
+        struct crypto_tfm *tfm;
+        char *tmp;
+        char *cipher;
+        char *chainmode;
+        char *ivmode;
+        char *ivopts;
+        unsigned int crypto_flags;
+        unsigned int key_size;
+
+        if (argc != 5) {
+                ti->error = PFX "Not enough arguments";
+                return -EINVAL;
+        }
+
+        tmp = argv[0];
+        cipher = strsep(&tmp, "-");
+        chainmode = strsep(&tmp, "-");
+        ivopts = strsep(&tmp, "-");
+        ivmode = strsep(&ivopts, ":");
+
+        if (tmp)
+                DMWARN(PFX "Unexpected additional cipher options");
+
+        key_size = strlen(argv[1]) >> 1;
+
+        cc = kmalloc(sizeof(*cc) + key_size * sizeof(u8), GFP_KERNEL);
+        if (cc == NULL) {
+                ti->error =
+                        PFX "Cannot allocate transparent encryption context";
+                return -ENOMEM;
+        }
+
+        cc->key_size = key_size;
+        if ((!key_size && strcmp(argv[1], "-") != 0) ||
+            (key_size && crypt_decode_key(cc->key, argv[1], key_size) < 0)) {
+                ti->error = PFX "Error decoding key";
+                goto bad1;
+        }
+
+        /* Compatiblity mode for old dm-crypt cipher strings */
+        if (!chainmode || (strcmp(chainmode, "plain") == 0 && !ivmode)) {
+                chainmode = "cbc";
+                ivmode = "plain";
+        }
+
+        /* Choose crypto_flags according to chainmode */
+        if (strcmp(chainmode, "cbc") == 0)
+                crypto_flags = CRYPTO_TFM_MODE_CBC;
+        else if (strcmp(chainmode, "ecb") == 0)
+                crypto_flags = CRYPTO_TFM_MODE_ECB;
+        else {
+                ti->error = PFX "Unknown chaining mode";
+                goto bad1;
+        }
+
+        if (crypto_flags != CRYPTO_TFM_MODE_ECB && !ivmode) {
+                ti->error = PFX "This chaining mode requires an IV mechanism";
+                goto bad1;
+        }
+
+        tfm = crypto_alloc_tfm(cipher, crypto_flags);
+        if (!tfm) {
+                ti->error = PFX "Error allocating crypto tfm";
+                goto bad1;
+        }
+        if (crypto_tfm_alg_type(tfm) != CRYPTO_ALG_TYPE_CIPHER) {
+                ti->error = PFX "Expected cipher algorithm";
+                goto bad2;
+        }
+
+        cc->tfm = tfm;
+
+        /*
+         * Choose ivmode. Valid modes: "plain", "essiv:<esshash>".
+         * 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, "essiv") == 0)
+                cc->iv_gen_ops = &crypt_iv_essiv_ops;
+        else {
+                ti->error = PFX "Invalid IV mode";
+                goto bad2;
+        }
+
+        if (cc->iv_gen_ops && cc->iv_gen_ops->ctr &&
+            cc->iv_gen_ops->ctr(cc, ti, ivopts) < 0)
+                goto bad2;
+
+        if (tfm->crt_cipher.cit_decrypt_iv && tfm->crt_cipher.cit_encrypt_iv)
+                /* at least a 64 bit sector number should fit in our buffer */
+                cc->iv_size = max(crypto_tfm_alg_ivsize(tfm),
+                                  (unsigned int)(sizeof(u64) / sizeof(u8)));
+        else {
+                cc->iv_size = 0;
+                if (cc->iv_gen_ops) {
+                        DMWARN(PFX "Selected cipher does not support IVs");
+                        if (cc->iv_gen_ops->dtr)
+                                cc->iv_gen_ops->dtr(cc);
+                        cc->iv_gen_ops = NULL;
+                }
+        }
+
+        cc->io_pool = mempool_create(MIN_IOS, mempool_alloc_slab,
+                                     mempool_free_slab, _crypt_io_pool);
+        if (!cc->io_pool) {
+                ti->error = PFX "Cannot allocate crypt io mempool";
+                goto bad3;
+        }
+
+        cc->page_pool = mempool_create(MIN_POOL_PAGES, mempool_alloc_page,
+                                       mempool_free_page, NULL);
+        if (!cc->page_pool) {
+                ti->error = PFX "Cannot allocate page mempool";
+                goto bad4;
+        }
+
+        if (tfm->crt_cipher.cit_setkey(tfm, cc->key, key_size) < 0) {
+                ti->error = PFX "Error setting key";
+                goto bad5;
+        }
+
+        if (sscanf(argv[2], SECTOR_FORMAT, &cc->iv_offset) != 1) {
+                ti->error = PFX "Invalid iv_offset sector";
+                goto bad5;
+        }
+
+        if (sscanf(argv[4], SECTOR_FORMAT, &cc->start) != 1) {
+                ti->error = PFX "Invalid device sector";
+                goto bad5;
+        }
+
+        if (dm_get_device(ti, argv[3], cc->start, ti->len,
+                          dm_table_get_mode(ti->table), &cc->dev)) {
+                ti->error = PFX "Device lookup failed";
+                goto bad5;
+        }
+
+        if (ivmode && cc->iv_gen_ops) {
+                if (ivopts)
+                        *(ivopts - 1) = ':';
+                cc->iv_mode = kmalloc(strlen(ivmode) + 1, GFP_KERNEL);
+                if (!cc->iv_mode) {
+                        ti->error = PFX "Error kmallocing iv_mode string";
+                        goto bad5;
+                }
+                strcpy(cc->iv_mode, ivmode);
+        } else
+                cc->iv_mode = NULL;
+
+        ti->private = cc;
+        return 0;
+
+bad5:
+        mempool_destroy(cc->page_pool);
+bad4:
+        mempool_destroy(cc->io_pool);
+bad3:
+        if (cc->iv_gen_ops && cc->iv_gen_ops->dtr)
+                cc->iv_gen_ops->dtr(cc);
+bad2:
+        crypto_free_tfm(tfm);
+bad1:
+        kfree(cc);
+        return -EINVAL;
+}
+
+static void crypt_dtr(struct dm_target *ti)
+{
+        struct crypt_config *cc = (struct crypt_config *) ti->private;
+
+        mempool_destroy(cc->page_pool);
+        mempool_destroy(cc->io_pool);
+
+        if (cc->iv_mode)
+                kfree(cc->iv_mode);
+        if (cc->iv_gen_ops && cc->iv_gen_ops->dtr)
+                cc->iv_gen_ops->dtr(cc);
+        crypto_free_tfm(cc->tfm);
+        dm_put_device(ti, cc->dev);
+        kfree(cc);
+}
+
+static int crypt_endio(struct bio *bio, unsigned int done, int error)
+{
+        struct crypt_io *io = (struct crypt_io *) bio->bi_private;
+        struct crypt_config *cc = (struct crypt_config *) io->target->private;
+
+        if (bio_data_dir(bio) == WRITE) {
+                /*
+                 * free the processed pages, even if
+                 * it's only a partially completed write
+                 */
+                crypt_free_buffer_pages(cc, bio, done);
+        }
+
+        if (bio->bi_size)
+                return 1;
+
+        bio_put(bio);
+
+        /*
+         * successful reads are decrypted by the worker thread
+         */
+        if ((bio_data_dir(bio) == READ)
+            && bio_flagged(bio, BIO_UPTODATE)) {
+                kcryptd_queue_io(io);
+                return 0;
+        }
+
+        dec_pending(io, error);
+        return error;
+}
+
+static inline struct bio *
+crypt_clone(struct crypt_config *cc, struct crypt_io *io, struct bio *bio,
+            sector_t sector, unsigned int *bvec_idx,
+            struct convert_context *ctx)
+{
+        struct bio *clone;
+
+        if (bio_data_dir(bio) == WRITE) {
+                clone = crypt_alloc_buffer(cc, bio->bi_size,
+                                 io->first_clone, bvec_idx);
+                if (clone) {
+                        ctx->bio_out = clone;
+                        if (crypt_convert(cc, ctx) < 0) {
+                                crypt_free_buffer_pages(cc, clone,
+                                                        clone->bi_size);
+                                bio_put(clone);
+                                return NULL;
+                        }
+                }
+        } else {
+                /*
+                 * The block layer might modify the bvec array, so always
+                 * copy the required bvecs because we need the original
+                 * one in order to decrypt the whole bio data *afterwards*.
+                 */
+                clone = bio_alloc(GFP_NOIO, bio_segments(bio));
+                if (clone) {
+                        clone->bi_idx = 0;
+                        clone->bi_vcnt = bio_segments(bio);
+                        clone->bi_size = bio->bi_size;
+                        memcpy(clone->bi_io_vec, bio_iovec(bio),
+                               sizeof(struct bio_vec) * clone->bi_vcnt);
+                }
+        }
+
+        if (!clone)
+                return NULL;
+
+        clone->bi_private = io;
+        clone->bi_end_io = crypt_endio;
+        clone->bi_bdev = cc->dev->bdev;
+        clone->bi_sector = cc->start + sector;
+        clone->bi_rw = bio->bi_rw;
+
+        return clone;
+}
+
+static int crypt_map(struct dm_target *ti, struct bio *bio,
+                     union map_info *map_context)
+{
+        struct crypt_config *cc = (struct crypt_config *) ti->private;
+        struct crypt_io *io = mempool_alloc(cc->io_pool, GFP_NOIO);
+        struct convert_context ctx;
+        struct bio *clone;
+        unsigned int remaining = bio->bi_size;
+        sector_t sector = bio->bi_sector - ti->begin;
+        unsigned int bvec_idx = 0;
+
+        io->target = ti;
+        io->bio = bio;
+        io->first_clone = NULL;
+        io->error = 0;
+        atomic_set(&io->pending, 1); /* hold a reference */
+
+        if (bio_data_dir(bio) == WRITE)
+                crypt_convert_init(cc, &ctx, NULL, bio, sector, 1);
+
+        /*
+         * The allocated buffers can be smaller than the whole bio,
+         * so repeat the whole process until all the data can be handled.
+         */
+        while (remaining) {
+                clone = crypt_clone(cc, io, bio, sector, &bvec_idx, &ctx);
+                if (!clone)
+                        goto cleanup;
+
+                if (!io->first_clone) {
+                        /*
+                         * hold a reference to the first clone, because it
+                         * holds the bio_vec array and that can't be freed
+                         * before all other clones are released
+                         */
+                        bio_get(clone);
+                        io->first_clone = clone;
+                }
+                atomic_inc(&io->pending);
+
+                remaining -= clone->bi_size;
+                sector += bio_sectors(clone);
+
+                generic_make_request(clone);
+
+                /* out of memory -> run queues */
+                if (remaining)
+                        blk_congestion_wait(bio_data_dir(clone), HZ/100);
+        }
+
+        /* drop reference, clones could have returned before we reach this */
+        dec_pending(io, 0);
+        return 0;
+
+cleanup:
+        if (io->first_clone) {
+                dec_pending(io, -ENOMEM);
+                return 0;
+        }
+
+        /* if no bio has been dispatched yet, we can directly return the error */
+        mempool_free(io, cc->io_pool);
+        return -ENOMEM;
+}
+
+static int crypt_status(struct dm_target *ti, status_type_t type,
+                        char *result, unsigned int maxlen)
+{
+        struct crypt_config *cc = (struct crypt_config *) ti->private;
+        const char *cipher;
+        const char *chainmode = NULL;
+        unsigned int sz = 0;
+
+        switch (type) {
+        case STATUSTYPE_INFO:
+                result[0] = '\0';
+                break;
+
+        case STATUSTYPE_TABLE:
+                cipher = crypto_tfm_alg_name(cc->tfm);
+
+                switch(cc->tfm->crt_cipher.cit_mode) {
+                case CRYPTO_TFM_MODE_CBC:
+                        chainmode = "cbc";
+                        break;
+                case CRYPTO_TFM_MODE_ECB:
+                        chainmode = "ecb";
+                        break;
+                default:
+                        BUG();
+                }
+
+                if (cc->iv_mode)
+                        DMEMIT("%s-%s-%s ", cipher, chainmode, cc->iv_mode);
+                else
+                        DMEMIT("%s-%s ", cipher, chainmode);
+
+                if (cc->key_size > 0) {
+                        if ((maxlen - sz) < ((cc->key_size << 1) + 1))
+                                return -ENOMEM;
+
+                        crypt_encode_key(result + sz, cc->key, cc->key_size);
+                        sz += cc->key_size << 1;
+                } else {
+                        if (sz >= maxlen)
+                                return -ENOMEM;
+                        result[sz++] = '-';
+                }
+
+                DMEMIT(" " SECTOR_FORMAT " %s " SECTOR_FORMAT,
+                       cc->iv_offset, cc->dev->name, cc->start);
+                break;
+        }
+        return 0;
+}
+
+static struct target_type crypt_target = {
+        .name   = "crypt",
+        .version= {1, 1, 0},
+        .module = THIS_MODULE,
+        .ctr    = crypt_ctr,
+        .dtr    = crypt_dtr,
+        .map    = crypt_map,
+        .status = crypt_status,
+};
+
+static int __init dm_crypt_init(void)
+{
+        int r;
+
+        _crypt_io_pool = kmem_cache_create("dm-crypt_io",
+                                           sizeof(struct crypt_io),
+                                           0, 0, NULL, NULL);
+        if (!_crypt_io_pool)
+                return -ENOMEM;
+
+        _kcryptd_workqueue = create_workqueue("kcryptd");
+        if (!_kcryptd_workqueue) {
+                r = -ENOMEM;
+                DMERR(PFX "couldn't create kcryptd");
+                goto bad1;
+        }
+
+        r = dm_register_target(&crypt_target);
+        if (r < 0) {
+                DMERR(PFX "register failed %d", r);
+                goto bad2;
+        }
+
+        return 0;
+
+bad2:
+        destroy_workqueue(_kcryptd_workqueue);
+bad1:
+        kmem_cache_destroy(_crypt_io_pool);
+        return r;
+}
+
+static void __exit dm_crypt_exit(void)
+{
+        int r = dm_unregister_target(&crypt_target);
+
+        if (r < 0)
+                DMERR(PFX "unregister failed %d", r);
+
+        destroy_workqueue(_kcryptd_workqueue);
+        kmem_cache_destroy(_crypt_io_pool);
+}
+
+module_init(dm_crypt_init);
+module_exit(dm_crypt_exit);
+
+MODULE_AUTHOR("Christophe Saout <christophe@saout.de>");
+MODULE_DESCRIPTION(DM_NAME " target for transparent encryption / decryption");
+MODULE_LICENSE("GPL");