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32 results

random.c

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    • Mark Rutland's avatar
      ab9a7e27
      random: avoid warnings for !CONFIG_NUMA builds · ab9a7e27
      Mark Rutland authored
      As crng_initialize_secondary() is only called by do_numa_crng_init(),
      and the latter is under ifdeffery for CONFIG_NUMA, when CONFIG_NUMA is
      not selected the compiler will warn that the former is unused:
      
      | drivers/char/random.c:820:13: warning: 'crng_initialize_secondary' defined but not used [-Wunused-function]
      |   820 | static void crng_initialize_secondary(struct crng_state *crng)
      |       |             ^~~~~~~~~~~~~~~~~~~~~~~~~
      
      Stephen reports that this happens for x86_64 noallconfig builds.
      
      We could move crng_initialize_secondary() and crng_init_try_arch() under
      the CONFIG_NUMA ifdeffery, but this has the unfortunate property of
      separating them from crng_initialize_primary() and
      crng_init_try_arch_early() respectively. Instead, let's mark
      crng_initialize_secondary() as __maybe_unused.
      
      Link: https://lore.kernel.org/r/20200310121747.GA49602@lakrids.cambridge.arm.com
      
      
      Fixes: 5cbe0f13 ("random: split primary/secondary crng init paths")
      Reported-by: default avatarStephen Rothwell <sfr@canb.auug.org.au>
      Signed-off-by: default avatarMark Rutland <mark.rutland@arm.com>
      Cc: Theodore Ts'o <tytso@mit.edu>
      Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
      ab9a7e27
      History
      random: avoid warnings for !CONFIG_NUMA builds
      Mark Rutland authored
      As crng_initialize_secondary() is only called by do_numa_crng_init(),
      and the latter is under ifdeffery for CONFIG_NUMA, when CONFIG_NUMA is
      not selected the compiler will warn that the former is unused:
      
      | drivers/char/random.c:820:13: warning: 'crng_initialize_secondary' defined but not used [-Wunused-function]
      |   820 | static void crng_initialize_secondary(struct crng_state *crng)
      |       |             ^~~~~~~~~~~~~~~~~~~~~~~~~
      
      Stephen reports that this happens for x86_64 noallconfig builds.
      
      We could move crng_initialize_secondary() and crng_init_try_arch() under
      the CONFIG_NUMA ifdeffery, but this has the unfortunate property of
      separating them from crng_initialize_primary() and
      crng_init_try_arch_early() respectively. Instead, let's mark
      crng_initialize_secondary() as __maybe_unused.
      
      Link: https://lore.kernel.org/r/20200310121747.GA49602@lakrids.cambridge.arm.com
      
      
      Fixes: 5cbe0f13 ("random: split primary/secondary crng init paths")
      Reported-by: default avatarStephen Rothwell <sfr@canb.auug.org.au>
      Signed-off-by: default avatarMark Rutland <mark.rutland@arm.com>
      Cc: Theodore Ts'o <tytso@mit.edu>
      Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
    dm-crypt.c 28.89 KiB
    /*
     * Copyright (C) 2003 Christophe Saout <christophe@saout.de>
     * Copyright (C) 2004 Clemens Fruhwirth <clemens@endorphin.org>
     * Copyright (C) 2006-2007 Red Hat, Inc. All rights reserved.
     *
     * 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/bio.h>
    #include <linux/blkdev.h>
    #include <linux/mempool.h>
    #include <linux/slab.h>
    #include <linux/crypto.h>
    #include <linux/workqueue.h>
    #include <linux/backing-dev.h>
    #include <asm/atomic.h>
    #include <linux/scatterlist.h>
    #include <asm/page.h>
    #include <asm/unaligned.h>
    
    #include "dm.h"
    
    #define DM_MSG_PREFIX "crypt"
    #define MESG_STR(x) x, sizeof(x)
    
    /*
     * context holding the current state of a multi-part conversion
     */
    struct convert_context {
    	struct completion restart;
    	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;
    	atomic_t pending;
    };
    
    /*
     * per bio private data
     */
    struct dm_crypt_io {
    	struct dm_target *target;
    	struct bio *base_bio;
    	struct work_struct work;
    
    	struct convert_context ctx;
    
    	atomic_t pending;
    	int error;
    	sector_t sector;
    };
    
    struct dm_crypt_request {
    	struct scatterlist sg_in;
    	struct scatterlist sg_out;
    };
    
    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.
     */
    enum flags { DM_CRYPT_SUSPENDED, DM_CRYPT_KEY_VALID };
    struct crypt_config {
    	struct dm_dev *dev;
    	sector_t start;
    
    	/*
    	 * pool for per bio private data, crypto requests and
    	 * encryption requeusts/buffer pages
    	 */
    	mempool_t *io_pool;
    	mempool_t *req_pool;
    	mempool_t *page_pool;
    	struct bio_set *bs;
    
    	struct workqueue_struct *io_queue;
    	struct workqueue_struct *crypt_queue;
    	/*
    	 * crypto related data
    	 */
    	struct crypt_iv_operations *iv_gen_ops;
    	char *iv_mode;
    	union {
    		struct crypto_cipher *essiv_tfm;
    		int benbi_shift;
    	} iv_gen_private;
    	sector_t iv_offset;
    	unsigned int iv_size;
    
    	/*
    	 * Layout of each crypto request:
    	 *
    	 *   struct ablkcipher_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;
    	struct ablkcipher_request *req;
    
    	char cipher[CRYPTO_MAX_ALG_NAME];
    	char chainmode[CRYPTO_MAX_ALG_NAME];
    	struct crypto_blkcipher *tfm;
    	unsigned long flags;
    	unsigned int key_size;
    	u8 key[0];
    };
    
    #define MIN_IOS        16
    #define MIN_POOL_PAGES 32
    #define MIN_BIO_PAGES  8
    
    static struct kmem_cache *_crypt_io_pool;
    
    static void clone_init(struct dm_crypt_io *, struct bio *);
    static void kcryptd_queue_crypt(struct dm_crypt_io *io);
    
    /*
     * Different IV generation algorithms:
     *
     * plain: the initial vector is the 32-bit little-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.
     *
     * 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_cipher *essiv_tfm;
    	struct crypto_hash *hash_tfm;
    	struct hash_desc desc;
    	struct scatterlist sg;
    	unsigned int saltsize;
    	u8 *salt;
    	int err;
    
    	if (opts == NULL) {
    		ti->error = "Digest algorithm missing for ESSIV mode";
    		return -EINVAL;
    	}
    
    	/* Hash the cipher key with the given hash algorithm */
    	hash_tfm = crypto_alloc_hash(opts, 0, CRYPTO_ALG_ASYNC);
    	if (IS_ERR(hash_tfm)) {
    		ti->error = "Error initializing ESSIV hash";
    		return PTR_ERR(hash_tfm);
    	}
    
    	saltsize = crypto_hash_digestsize(hash_tfm);
    	salt = kmalloc(saltsize, GFP_KERNEL);
    	if (salt == NULL) {
    		ti->error = "Error kmallocing salt storage in ESSIV";
    		crypto_free_hash(hash_tfm);
    		return -ENOMEM;
    	}
    
    	sg_init_one(&sg, cc->key, cc->key_size);
    	desc.tfm = hash_tfm;
    	desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;
    	err = crypto_hash_digest(&desc, &sg, cc->key_size, salt);
    	crypto_free_hash(hash_tfm);
    
    	if (err) {
    		ti->error = "Error calculating hash in ESSIV";
    		kfree(salt);
    		return err;
    	}
    
    	/* Setup the essiv_tfm with the given salt */
    	essiv_tfm = crypto_alloc_cipher(cc->cipher, 0, CRYPTO_ALG_ASYNC);
    	if (IS_ERR(essiv_tfm)) {
    		ti->error = "Error allocating crypto tfm for ESSIV";
    		kfree(salt);
    		return PTR_ERR(essiv_tfm);
    	}
    	if (crypto_cipher_blocksize(essiv_tfm) !=
    	    crypto_blkcipher_ivsize(cc->tfm)) {
    		ti->error = "Block size of ESSIV cipher does "
    			    "not match IV size of block cipher";
    		crypto_free_cipher(essiv_tfm);
    		kfree(salt);
    		return -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);
    		kfree(salt);
    		return err;
    	}
    	kfree(salt);
    
    	cc->iv_gen_private.essiv_tfm = essiv_tfm;
    	return 0;
    }
    
    static void crypt_iv_essiv_dtr(struct crypt_config *cc)
    {
    	crypto_free_cipher(cc->iv_gen_private.essiv_tfm);
    	cc->iv_gen_private.essiv_tfm = NULL;
    }
    
    static int crypt_iv_essiv_gen(struct crypt_config *cc, u8 *iv, sector_t sector)
    {
    	memset(iv, 0, cc->iv_size);
    	*(u64 *)iv = cpu_to_le64(sector);
    	crypto_cipher_encrypt_one(cc->iv_gen_private.essiv_tfm, iv, iv);
    	return 0;
    }
    
    static int crypt_iv_benbi_ctr(struct crypt_config *cc, struct dm_target *ti,
    			      const char *opts)
    {
    	unsigned int bs = crypto_blkcipher_blocksize(cc->tfm);
    	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, sector_t sector)
    {
    	__be64 val;
    
    	memset(iv, 0, cc->iv_size - sizeof(u64)); /* rest is cleared below */
    
    	val = cpu_to_be64(((u64)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, sector_t sector)
    {
    	memset(iv, 0, 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 struct crypt_iv_operations crypt_iv_benbi_ops = {
    	.ctr	   = crypt_iv_benbi_ctr,
    	.dtr	   = crypt_iv_benbi_dtr,
    	.generator = crypt_iv_benbi_gen
    };
    
    static struct crypt_iv_operations crypt_iv_null_ops = {
    	.generator = crypt_iv_null_gen
    };
    
    static 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] __attribute__ ((aligned(__alignof__(u64))));
    	struct blkcipher_desc desc = {
    		.tfm = cc->tfm,
    		.info = iv,
    		.flags = CRYPTO_TFM_REQ_MAY_SLEEP,
    	};
    	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_blkcipher_encrypt_iv(&desc, out, in, length);
    		else
    			r = crypto_blkcipher_decrypt_iv(&desc, out, in, length);
    	} else {
    		if (write)
    			r = crypto_blkcipher_encrypt(&desc, out, in, length);
    		else
    			r = crypto_blkcipher_decrypt(&desc, 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)
    {
    	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;
    	init_completion(&ctx->restart);
    	/*
    	 * Crypto operation can be asynchronous,
    	 * ctx->pending is increased after request submission.
    	 * We need to ensure that we don't call the crypt finish
    	 * operation before pending got incremented
    	 * (dependent on crypt submission return code).
    	 */
    	atomic_set(&ctx->pending, 2);
    }
    
    static int crypt_convert_block(struct crypt_config *cc,
    			       struct convert_context *ctx)
    {
    	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 dm_crypt_request dmreq;
    
    	sg_init_table(&dmreq.sg_in, 1);
    	sg_set_page(&dmreq.sg_in, bv_in->bv_page, 1 << SECTOR_SHIFT,
    		    bv_in->bv_offset + ctx->offset_in);
    
    	sg_init_table(&dmreq.sg_out, 1);
    	sg_set_page(&dmreq.sg_out, bv_out->bv_page, 1 << SECTOR_SHIFT,
    		    bv_out->bv_offset + ctx->offset_out);
    
    	ctx->offset_in += 1 << SECTOR_SHIFT;
    	if (ctx->offset_in >= bv_in->bv_len) {
    		ctx->offset_in = 0;
    		ctx->idx_in++;
    	}
    
    	ctx->offset_out += 1 << SECTOR_SHIFT;
    	if (ctx->offset_out >= bv_out->bv_len) {
    		ctx->offset_out = 0;
    		ctx->idx_out++;
    	}
    
    	return crypt_convert_scatterlist(cc, &dmreq.sg_out, &dmreq.sg_in,
    					 dmreq.sg_in.length,
    					 bio_data_dir(ctx->bio_in) == WRITE,
    					 ctx->sector);
    }
    
    static void kcryptd_async_done(struct crypto_async_request *async_req,
    			       int error);
    static void crypt_alloc_req(struct crypt_config *cc,
    			    struct convert_context *ctx)
    {
    	if (!cc->req)
    		cc->req = mempool_alloc(cc->req_pool, GFP_NOIO);
    	ablkcipher_request_set_tfm(cc->req, cc->tfm);
    	ablkcipher_request_set_callback(cc->req, CRYPTO_TFM_REQ_MAY_BACKLOG |
    					     CRYPTO_TFM_REQ_MAY_SLEEP,
    					     kcryptd_async_done, ctx);
    }
    
    /*
     * 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) {
    		r = crypt_convert_block(cc, ctx);
    		if (r < 0)
    			break;
    
    		ctx->sector++;
    	}
    
    	/*
    	 * If there are pending crypto operation run async
    	 * code. Otherwise process return code synchronously.
    	 * The step of 2 ensures that async finish doesn't
    	 * call crypto finish too early.
    	 */
    	if (atomic_sub_return(2, &ctx->pending))
    		return -EINPROGRESS;
    
    	return r;
    }
    
    static void dm_crypt_bio_destructor(struct bio *bio)
    {
    	struct dm_crypt_io *io = bio->bi_private;
    	struct crypt_config *cc = io->target->private;
    
    	bio_free(bio, cc->bs);
    }
    
    /*
     * 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 dm_crypt_io *io, unsigned size)
    {
    	struct crypt_config *cc = io->target->private;
    	struct bio *clone;
    	unsigned int nr_iovecs = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
    	gfp_t gfp_mask = GFP_NOIO | __GFP_HIGHMEM;
    	unsigned i, len;
    	struct page *page;
    
    	clone = bio_alloc_bioset(GFP_NOIO, nr_iovecs, cc->bs);
    	if (!clone)
    		return NULL;
    
    	clone_init(io, clone);
    
    	for (i = 0; i < nr_iovecs; i++) {
    		page = mempool_alloc(cc->page_pool, gfp_mask);
    		if (!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 == (MIN_BIO_PAGES - 1))
    			gfp_mask = (gfp_mask | __GFP_NOWARN) & ~__GFP_WAIT;
    
    		len = (size > PAGE_SIZE) ? PAGE_SIZE : size;
    
    		if (!bio_add_page(clone, page, len, 0)) {
    			mempool_free(page, cc->page_pool);
    			break;
    		}
    
    		size -= len;
    	}
    
    	if (!clone->bi_size) {
    		bio_put(clone);
    		return NULL;
    	}
    
    	return clone;
    }
    
    static void crypt_free_buffer_pages(struct crypt_config *cc, struct bio *clone)
    {
    	unsigned int i;
    	struct bio_vec *bv;
    
    	for (i = 0; i < clone->bi_vcnt; i++) {
    		bv = bio_iovec_idx(clone, 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 crypt_dec_pending(struct dm_crypt_io *io)
    {
    	struct crypt_config *cc = io->target->private;
    
    	if (!atomic_dec_and_test(&io->pending))
    		return;
    
    	bio_endio(io->base_bio, io->error);
    	mempool_free(io, cc->io_pool);
    }
    
    /*
     * 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.
     */
    static void crypt_endio(struct bio *clone, int error)
    {
    	struct dm_crypt_io *io = clone->bi_private;
    	struct crypt_config *cc = io->target->private;
    	unsigned rw = bio_data_dir(clone);
    
    	if (unlikely(!bio_flagged(clone, BIO_UPTODATE) && !error))
    		error = -EIO;
    
    	/*
    	 * free the processed pages
    	 */
    	if (rw == WRITE)
    		crypt_free_buffer_pages(cc, clone);
    
    	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->target->private;
    
    	clone->bi_private = io;
    	clone->bi_end_io  = crypt_endio;
    	clone->bi_bdev    = cc->dev->bdev;
    	clone->bi_rw      = io->base_bio->bi_rw;
    	clone->bi_destructor = dm_crypt_bio_destructor;
    }
    
    static void kcryptd_io_read(struct dm_crypt_io *io)
    {
    	struct crypt_config *cc = io->target->private;
    	struct bio *base_bio = io->base_bio;
    	struct bio *clone;
    
    	atomic_inc(&io->pending);
    
    	/*
    	 * 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_bioset(GFP_NOIO, bio_segments(base_bio), cc->bs);
    	if (unlikely(!clone)) {
    		io->error = -ENOMEM;
    		crypt_dec_pending(io);
    		return;
    	}
    
    	clone_init(io, clone);
    	clone->bi_idx = 0;
    	clone->bi_vcnt = bio_segments(base_bio);
    	clone->bi_size = base_bio->bi_size;
    	clone->bi_sector = cc->start + io->sector;
    	memcpy(clone->bi_io_vec, bio_iovec(base_bio),
    	       sizeof(struct bio_vec) * clone->bi_vcnt);
    
    	generic_make_request(clone);
    }
    
    static void kcryptd_io_write(struct dm_crypt_io *io)
    {
    	struct bio *clone = io->ctx.bio_out;
    
    	generic_make_request(clone);
    }
    
    static void kcryptd_io(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_io_read(io);
    	else
    		kcryptd_io_write(io);
    }
    
    static void kcryptd_queue_io(struct dm_crypt_io *io)
    {
    	struct crypt_config *cc = io->target->private;
    
    	INIT_WORK(&io->work, kcryptd_io);
    	queue_work(cc->io_queue, &io->work);
    }
    
    static void kcryptd_crypt_write_io_submit(struct dm_crypt_io *io,
    					  int error, int async)
    {
    	struct bio *clone = io->ctx.bio_out;
    	struct crypt_config *cc = io->target->private;
    
    	if (unlikely(error < 0)) {
    		crypt_free_buffer_pages(cc, clone);
    		bio_put(clone);
    		io->error = -EIO;
    		return;
    	}
    
    	/* crypt_convert should have filled the clone bio */
    	BUG_ON(io->ctx.idx_out < clone->bi_vcnt);
    
    	clone->bi_sector = cc->start + io->sector;
    	io->sector += bio_sectors(clone);
    
    	if (async)
    		kcryptd_queue_io(io);
    	else {
    		atomic_inc(&io->pending);
    		generic_make_request(clone);
    	}
    }
    
    static void kcryptd_crypt_write_convert_loop(struct dm_crypt_io *io)
    {
    	struct crypt_config *cc = io->target->private;
    	struct bio *clone;
    	unsigned remaining = io->base_bio->bi_size;
    	int r;
    
    	/*
    	 * 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_alloc_buffer(io, remaining);
    		if (unlikely(!clone)) {
    			io->error = -ENOMEM;
    			return;
    		}
    
    		io->ctx.bio_out = clone;
    		io->ctx.idx_out = 0;
    
    		remaining -= clone->bi_size;
    
    		r = crypt_convert(cc, &io->ctx);
    
    		kcryptd_crypt_write_io_submit(io, r, 0);
    		if (unlikely(r < 0))
    			return;
    
    		/* out of memory -> run queues */
    		if (unlikely(remaining))
    			congestion_wait(WRITE, HZ/100);
    	}
    }
    
    static void kcryptd_crypt_write_convert(struct dm_crypt_io *io)
    {
    	struct crypt_config *cc = io->target->private;
    
    	/*
    	 * Prevent io from disappearing until this function completes.
    	 */
    	atomic_inc(&io->pending);
    
    	crypt_convert_init(cc, &io->ctx, NULL, io->base_bio, io->sector);
    	kcryptd_crypt_write_convert_loop(io);
    
    	crypt_dec_pending(io);
    }
    
    static void kcryptd_crypt_read_done(struct dm_crypt_io *io, int error)
    {
    	if (unlikely(error < 0))
    		io->error = -EIO;
    
    	crypt_dec_pending(io);
    }
    
    static void kcryptd_crypt_read_convert(struct dm_crypt_io *io)
    {
    	struct crypt_config *cc = io->target->private;
    	int r = 0;
    
    	crypt_convert_init(cc, &io->ctx, io->base_bio, io->base_bio,
    			   io->sector);
    
    	r = crypt_convert(cc, &io->ctx);
    
    	kcryptd_crypt_read_done(io, r);
    }
    
    static void kcryptd_async_done(struct crypto_async_request *async_req,
    			       int error)
    {
    	struct convert_context *ctx = async_req->data;
    	struct dm_crypt_io *io = container_of(ctx, struct dm_crypt_io, ctx);
    	struct crypt_config *cc = io->target->private;
    
    	if (error == -EINPROGRESS) {
    		complete(&ctx->restart);
    		return;
    	}
    
    	mempool_free(ablkcipher_request_cast(async_req), cc->req_pool);
    
    	if (!atomic_dec_and_test(&ctx->pending))
    		return;
    
    	if (bio_data_dir(io->base_bio) == READ)
    		kcryptd_crypt_read_done(io, error);
    	else
    		kcryptd_crypt_write_io_submit(io, error, 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->target->private;
    
    	INIT_WORK(&io->work, kcryptd_crypt);
    	queue_work(cc->crypt_queue, &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++;
    	}
    }
    
    static int crypt_set_key(struct crypt_config *cc, char *key)
    {
    	unsigned key_size = strlen(key) >> 1;
    
    	if (cc->key_size && cc->key_size != key_size)
    		return -EINVAL;
    
    	cc->key_size = key_size; /* initial settings */
    
    	if ((!key_size && strcmp(key, "-")) ||
    	   (key_size && crypt_decode_key(cc->key, key, key_size) < 0))
    		return -EINVAL;
    
    	set_bit(DM_CRYPT_KEY_VALID, &cc->flags);
    
    	return 0;
    }
    
    static int crypt_wipe_key(struct crypt_config *cc)
    {
    	clear_bit(DM_CRYPT_KEY_VALID, &cc->flags);
    	memset(&cc->key, 0, cc->key_size * sizeof(u8));
    	return 0;
    }
    
    /*
     * 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_blkcipher *tfm;
    	char *tmp;
    	char *cipher;
    	char *chainmode;
    	char *ivmode;
    	char *ivopts;
    	unsigned int key_size;
    	unsigned long long tmpll;
    
    	if (argc != 5) {
    		ti->error = "Not enough arguments";
    		return -EINVAL;
    	}
    
    	tmp = argv[0];
    	cipher = strsep(&tmp, "-");
    	chainmode = strsep(&tmp, "-");
    	ivopts = strsep(&tmp, "-");
    	ivmode = strsep(&ivopts, ":");
    
    	if (tmp)
    		DMWARN("Unexpected additional cipher options");
    
    	key_size = strlen(argv[1]) >> 1;
    
     	cc = kzalloc(sizeof(*cc) + key_size * sizeof(u8), GFP_KERNEL);
    	if (cc == NULL) {
    		ti->error =
    			"Cannot allocate transparent encryption context";
    		return -ENOMEM;
    	}
    
     	if (crypt_set_key(cc, argv[1])) {
    		ti->error = "Error decoding key";
    		goto bad_cipher;
    	}
    
    	/* Compatiblity mode for old dm-crypt cipher strings */
    	if (!chainmode || (strcmp(chainmode, "plain") == 0 && !ivmode)) {
    		chainmode = "cbc";
    		ivmode = "plain";
    	}
    
    	if (strcmp(chainmode, "ecb") && !ivmode) {
    		ti->error = "This chaining mode requires an IV mechanism";
    		goto bad_cipher;
    	}
    
    	if (snprintf(cc->cipher, CRYPTO_MAX_ALG_NAME, "%s(%s)",
    		     chainmode, cipher) >= CRYPTO_MAX_ALG_NAME) {
    		ti->error = "Chain mode + cipher name is too long";
    		goto bad_cipher;
    	}
    
    	tfm = crypto_alloc_blkcipher(cc->cipher, 0, CRYPTO_ALG_ASYNC);
    	if (IS_ERR(tfm)) {
    		ti->error = "Error allocating crypto tfm";
    		goto bad_cipher;
    	}
    
    	strcpy(cc->cipher, cipher);
    	strcpy(cc->chainmode, chainmode);
    	cc->tfm = tfm;
    
    	/*
    	 * Choose ivmode. Valid modes: "plain", "essiv:<esshash>", "benbi".
    	 * 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 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 {
    		ti->error = "Invalid IV mode";
    		goto bad_ivmode;
    	}
    
    	if (cc->iv_gen_ops && cc->iv_gen_ops->ctr &&
    	    cc->iv_gen_ops->ctr(cc, ti, ivopts) < 0)
    		goto bad_ivmode;
    
    	cc->iv_size = crypto_blkcipher_ivsize(tfm);
    	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 (cc->iv_gen_ops) {
    			DMWARN("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_slab_pool(MIN_IOS, _crypt_io_pool);
    	if (!cc->io_pool) {
    		ti->error = "Cannot allocate crypt io mempool";
    		goto bad_slab_pool;
    	}
    
    	cc->dmreq_start = sizeof(struct ablkcipher_request);
    	cc->dmreq_start = ALIGN(cc->dmreq_start, crypto_tfm_ctx_alignment());
    
    	cc->req_pool = mempool_create_kmalloc_pool(MIN_IOS, cc->dmreq_start +
    			sizeof(struct dm_crypt_request) + cc->iv_size);
    	if (!cc->req_pool) {
    		ti->error = "Cannot allocate crypt request mempool";
    		goto bad_req_pool;
    	}
    	cc->req = NULL;
    
    	cc->page_pool = mempool_create_page_pool(MIN_POOL_PAGES, 0);
    	if (!cc->page_pool) {
    		ti->error = "Cannot allocate page mempool";
    		goto bad_page_pool;
    	}
    
    	cc->bs = bioset_create(MIN_IOS, MIN_IOS);
    	if (!cc->bs) {
    		ti->error = "Cannot allocate crypt bioset";
    		goto bad_bs;
    	}
    
    	if (crypto_blkcipher_setkey(tfm, cc->key, key_size) < 0) {
    		ti->error = "Error setting key";
    		goto bad_device;
    	}
    
    	if (sscanf(argv[2], "%llu", &tmpll) != 1) {
    		ti->error = "Invalid iv_offset sector";
    		goto bad_device;
    	}
    	cc->iv_offset = tmpll;
    
    	if (sscanf(argv[4], "%llu", &tmpll) != 1) {
    		ti->error = "Invalid device sector";
    		goto bad_device;
    	}
    	cc->start = tmpll;
    
    	if (dm_get_device(ti, argv[3], cc->start, ti->len,
    			  dm_table_get_mode(ti->table), &cc->dev)) {
    		ti->error = "Device lookup failed";
    		goto bad_device;
    	}
    
    	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 = "Error kmallocing iv_mode string";
    			goto bad_ivmode_string;
    		}
    		strcpy(cc->iv_mode, ivmode);
    	} else
    		cc->iv_mode = NULL;
    
    	cc->io_queue = create_singlethread_workqueue("kcryptd_io");
    	if (!cc->io_queue) {
    		ti->error = "Couldn't create kcryptd io queue";
    		goto bad_io_queue;
    	}
    
    	cc->crypt_queue = create_singlethread_workqueue("kcryptd");
    	if (!cc->crypt_queue) {
    		ti->error = "Couldn't create kcryptd queue";
    		goto bad_crypt_queue;
    	}
    
    	ti->private = cc;
    	return 0;
    
    bad_crypt_queue:
    	destroy_workqueue(cc->io_queue);
    bad_io_queue:
    	kfree(cc->iv_mode);
    bad_ivmode_string:
    	dm_put_device(ti, cc->dev);
    bad_device:
    	bioset_free(cc->bs);
    bad_bs:
    	mempool_destroy(cc->page_pool);
    bad_page_pool:
    	mempool_destroy(cc->req_pool);
    bad_req_pool:
    	mempool_destroy(cc->io_pool);
    bad_slab_pool:
    	if (cc->iv_gen_ops && cc->iv_gen_ops->dtr)
    		cc->iv_gen_ops->dtr(cc);
    bad_ivmode:
    	crypto_free_blkcipher(tfm);
    bad_cipher:
    	/* Must zero key material before freeing */
    	memset(cc, 0, sizeof(*cc) + cc->key_size * sizeof(u8));
    	kfree(cc);
    	return -EINVAL;
    }
    
    static void crypt_dtr(struct dm_target *ti)
    {
    	struct crypt_config *cc = (struct crypt_config *) ti->private;
    
    	destroy_workqueue(cc->io_queue);
    	destroy_workqueue(cc->crypt_queue);
    
    	if (cc->req)
    		mempool_free(cc->req, cc->req_pool);
    
    	bioset_free(cc->bs);
    	mempool_destroy(cc->page_pool);
    	mempool_destroy(cc->req_pool);
    	mempool_destroy(cc->io_pool);
    
    	kfree(cc->iv_mode);
    	if (cc->iv_gen_ops && cc->iv_gen_ops->dtr)
    		cc->iv_gen_ops->dtr(cc);
    	crypto_free_blkcipher(cc->tfm);
    	dm_put_device(ti, cc->dev);
    
    	/* Must zero key material before freeing */
    	memset(cc, 0, sizeof(*cc) + cc->key_size * sizeof(u8));
    	kfree(cc);
    }
    
    static int crypt_map(struct dm_target *ti, struct bio *bio,
    		     union map_info *map_context)
    {
    	struct crypt_config *cc = ti->private;
    	struct dm_crypt_io *io;
    
    	io = mempool_alloc(cc->io_pool, GFP_NOIO);
    	io->target = ti;
    	io->base_bio = bio;
    	io->sector = bio->bi_sector - ti->begin;
    	io->error = 0;
    	atomic_set(&io->pending, 0);
    
    	if (bio_data_dir(io->base_bio) == READ)
    		kcryptd_queue_io(io);
    	else
    		kcryptd_queue_crypt(io);
    
    	return DM_MAPIO_SUBMITTED;
    }
    
    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;
    	unsigned int sz = 0;
    
    	switch (type) {
    	case STATUSTYPE_INFO:
    		result[0] = '\0';
    		break;
    
    	case STATUSTYPE_TABLE:
    		if (cc->iv_mode)
    			DMEMIT("%s-%s-%s ", cc->cipher, cc->chainmode,
    			       cc->iv_mode);
    		else
    			DMEMIT("%s-%s ", cc->cipher, cc->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(" %llu %s %llu", (unsigned long long)cc->iv_offset,
    				cc->dev->name, (unsigned long long)cc->start);
    		break;
    	}
    	return 0;
    }
    
    static void crypt_postsuspend(struct dm_target *ti)
    {
    	struct crypt_config *cc = ti->private;
    
    	set_bit(DM_CRYPT_SUSPENDED, &cc->flags);
    }
    
    static int crypt_preresume(struct dm_target *ti)
    {
    	struct crypt_config *cc = ti->private;
    
    	if (!test_bit(DM_CRYPT_KEY_VALID, &cc->flags)) {
    		DMERR("aborting resume - crypt key is not set.");
    		return -EAGAIN;
    	}
    
    	return 0;
    }
    
    static void crypt_resume(struct dm_target *ti)
    {
    	struct crypt_config *cc = ti->private;
    
    	clear_bit(DM_CRYPT_SUSPENDED, &cc->flags);
    }
    
    /* Message interface
     *	key set <key>
     *	key wipe
     */
    static int crypt_message(struct dm_target *ti, unsigned argc, char **argv)
    {
    	struct crypt_config *cc = ti->private;
    
    	if (argc < 2)
    		goto error;
    
    	if (!strnicmp(argv[0], MESG_STR("key"))) {
    		if (!test_bit(DM_CRYPT_SUSPENDED, &cc->flags)) {
    			DMWARN("not suspended during key manipulation.");
    			return -EINVAL;
    		}
    		if (argc == 3 && !strnicmp(argv[1], MESG_STR("set")))
    			return crypt_set_key(cc, argv[2]);
    		if (argc == 2 && !strnicmp(argv[1], MESG_STR("wipe")))
    			return crypt_wipe_key(cc);
    	}
    
    error:
    	DMWARN("unrecognised message received.");
    	return -EINVAL;
    }
    
    static struct target_type crypt_target = {
    	.name   = "crypt",
    	.version= {1, 5, 0},
    	.module = THIS_MODULE,
    	.ctr    = crypt_ctr,
    	.dtr    = crypt_dtr,
    	.map    = crypt_map,
    	.status = crypt_status,
    	.postsuspend = crypt_postsuspend,
    	.preresume = crypt_preresume,
    	.resume = crypt_resume,
    	.message = crypt_message,
    };
    
    static int __init dm_crypt_init(void)
    {
    	int r;
    
    	_crypt_io_pool = KMEM_CACHE(dm_crypt_io, 0);
    	if (!_crypt_io_pool)
    		return -ENOMEM;
    
    	r = dm_register_target(&crypt_target);
    	if (r < 0) {
    		DMERR("register failed %d", r);
    		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("unregister failed %d", r);
    
    	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");