diff options
Diffstat (limited to 'drivers/md/dm-crypt.c')
| -rw-r--r-- | drivers/md/dm-crypt.c | 1357 |
1 files changed, 1357 insertions, 0 deletions
diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c new file mode 100644 index 0000000..51047d3 --- /dev/null +++ b/drivers/md/dm-crypt.c @@ -0,0 +1,1357 @@ +/* + * Copyright (C) 2003 Christophe Saout <christophe@saout.de> + * Copyright (C) 2004 Clemens Fruhwirth <clemens@endorphin.org> + * Copyright (C) 2006-2008 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 <linux/device-mapper.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_io *base_io; +}; + +struct dm_crypt_request { + struct convert_context *ctx; + 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_ablkcipher *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_ablkcipher_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 bs = crypto_ablkcipher_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 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); +} + +static struct dm_crypt_request *dmreq_of_req(struct crypt_config *cc, + struct ablkcipher_request *req) +{ + return (struct dm_crypt_request *)((char *)req + cc->dmreq_start); +} + +static struct ablkcipher_request *req_of_dmreq(struct crypt_config *cc, + struct dm_crypt_request *dmreq) +{ + return (struct ablkcipher_request *)((char *)dmreq - cc->dmreq_start); +} + +static int crypt_convert_block(struct crypt_config *cc, + struct convert_context *ctx, + struct ablkcipher_request *req) +{ + 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; + u8 *iv; + int r = 0; + + dmreq = dmreq_of_req(cc, req); + iv = (u8 *)ALIGN((unsigned long)(dmreq + 1), + crypto_ablkcipher_alignmask(cc->tfm) + 1); + + dmreq->ctx = ctx; + 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++; + } + + if (cc->iv_gen_ops) { + r = cc->iv_gen_ops->generator(cc, iv, ctx->sector); + if (r < 0) + return r; + } + + ablkcipher_request_set_crypt(req, &dmreq->sg_in, &dmreq->sg_out, + 1 << SECTOR_SHIFT, iv); + + if (bio_data_dir(ctx->bio_in) == WRITE) + r = crypto_ablkcipher_encrypt(req); + else + r = crypto_ablkcipher_decrypt(req); + + return r; +} + +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, + dmreq_of_req(cc, cc->req)); +} + +/* + * 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; + + atomic_set(&ctx->pending, 1); + + while(ctx->idx_in < ctx->bio_in->bi_vcnt && + ctx->idx_out < ctx->bio_out->bi_vcnt) { + + crypt_alloc_req(cc, ctx); + + atomic_inc(&ctx->pending); + + r = crypt_convert_block(cc, ctx, cc->req); + + switch (r) { + /* async */ + case -EBUSY: + wait_for_completion(&ctx->restart); + INIT_COMPLETION(ctx->restart); + /* fall through*/ + case -EINPROGRESS: + cc->req = NULL; + ctx->sector++; + continue; + + /* sync */ + case 0: + atomic_dec(&ctx->pending); + ctx->sector++; + cond_resched(); + continue; + + /* error */ + default: + atomic_dec(&ctx->pending); + return r; + } + } + + return 0; +} + +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, indicated by + * *out_of_pages set to 1. + */ +static struct bio *crypt_alloc_buffer(struct dm_crypt_io *io, unsigned size, + unsigned *out_of_pages) +{ + 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); + *out_of_pages = 0; + + for (i = 0; i < nr_iovecs; i++) { + page = mempool_alloc(cc->page_pool, gfp_mask); + if (!page) { + *out_of_pages = 1; + 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; + } +} + +static struct dm_crypt_io *crypt_io_alloc(struct dm_target *ti, + struct bio *bio, sector_t sector) +{ + 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 = sector; + io->error = 0; + io->base_io = NULL; + atomic_set(&io->pending, 0); + + return io; +} + +static void crypt_inc_pending(struct dm_crypt_io *io) +{ + atomic_inc(&io->pending); +} + +/* + * One of the bios was finished. Check for completion of + * the whole request and correctly clean up the buffer. + * If base_io is set, wait for the last fragment to complete. + */ +static void crypt_dec_pending(struct dm_crypt_io *io) +{ + struct crypt_config *cc = io->target->private; + struct bio *base_bio = io->base_bio; + struct dm_crypt_io *base_io = io->base_io; + int error = io->error; + + if (!atomic_dec_and_test(&io->pending)) + return; + + mempool_free(io, cc->io_pool); + + if (likely(!base_io)) + bio_endio(base_bio, error); + else { + if (error && !base_io->error) + base_io->error = error; + crypt_dec_pending(base_io); + } +} + +/* + * 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; + + crypt_inc_pending(io); + + /* + * 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; + crypt_dec_pending(io); + 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; + + if (async) + kcryptd_queue_io(io); + else + generic_make_request(clone); +} + +static void kcryptd_crypt_write_convert(struct dm_crypt_io *io) +{ + struct crypt_config *cc = io->target->private; + struct bio *clone; + struct dm_crypt_io *new_io; + int crypt_finished; + unsigned out_of_pages = 0; + unsigned remaining = io->base_bio->bi_size; + sector_t sector = io->sector; + int r; + + /* + * Prevent io from disappearing until this function completes. + */ + crypt_inc_pending(io); + crypt_convert_init(cc, &io->ctx, NULL, io->base_bio, sector); + + /* + * 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, &out_of_pages); + if (unlikely(!clone)) { + io->error = -ENOMEM; + break; + } + + io->ctx.bio_out = clone; + io->ctx.idx_out = 0; + + remaining -= clone->bi_size; + sector += bio_sectors(clone); + + crypt_inc_pending(io); + r = crypt_convert(cc, &io->ctx); + crypt_finished = atomic_dec_and_test(&io->ctx.pending); + + /* Encryption was already finished, submit io now */ + if (crypt_finished) { + kcryptd_crypt_write_io_submit(io, r, 0); + + /* + * If there was an error, do not try next fragments. + * For async, error is processed in async handler. + */ + if (unlikely(r < 0)) + break; + + io->sector = sector; + } + + /* + * Out of memory -> run queues + * But don't wait if split was due to the io size restriction + */ + if (unlikely(out_of_pages)) + congestion_wait(WRITE, HZ/100); + + /* + * With async crypto it is unsafe to share the crypto context + * between fragments, so switch to a new dm_crypt_io structure. + */ + if (unlikely(!crypt_finished && remaining)) { + new_io = crypt_io_alloc(io->target, io->base_bio, + sector); + crypt_inc_pending(new_io); + crypt_convert_init(cc, &new_io->ctx, NULL, + io->base_bio, sector); + new_io->ctx.idx_in = io->ctx.idx_in; + new_io->ctx.offset_in = io->ctx.offset_in; + + /* + * Fragments after the first use the base_io + * pending count. + */ + if (!io->base_io) + new_io->base_io = io; + else { + new_io->base_io = io->base_io; + crypt_inc_pending(io->base_io); + crypt_dec_pending(io); + } + + io = new_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_inc_pending(io); + + crypt_convert_init(cc, &io->ctx, io->base_bio, io->base_bio, + io->sector); + + r = crypt_convert(cc, &io->ctx); + + if (atomic_dec_and_test(&io->ctx.pending)) + kcryptd_crypt_read_done(io, r); + + 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->target->private; + + if (error == -EINPROGRESS) { + complete(&ctx->restart); + return; + } + + mempool_free(req_of_dmreq(cc, dmreq), 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_ablkcipher *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_ablkcipher(cc->cipher, 0, 0); + 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_ablkcipher_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 += crypto_ablkcipher_reqsize(tfm); + cc->dmreq_start = ALIGN(cc->dmreq_start, crypto_tfm_ctx_alignment()); + cc->dmreq_start += crypto_ablkcipher_alignmask(tfm) & + ~(crypto_tfm_ctx_alignment() - 1); + + 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_ablkcipher_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_ablkcipher(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_ablkcipher(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 dm_crypt_io *io; + + io = crypt_io_alloc(ti, bio, bio->bi_sector - ti->begin); + + 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 int crypt_merge(struct dm_target *ti, struct bvec_merge_data *bvm, + struct bio_vec *biovec, int max_size) +{ + struct crypt_config *cc = ti->private; + struct request_queue *q = bdev_get_queue(cc->dev->bdev); + + if (!q->merge_bvec_fn) + return max_size; + + bvm->bi_bdev = cc->dev->bdev; + bvm->bi_sector = cc->start + bvm->bi_sector - ti->begin; + + return min(max_size, q->merge_bvec_fn(q, bvm, biovec)); +} + +static struct target_type crypt_target = { + .name = "crypt", + .version= {1, 6, 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, + .merge = crypt_merge, +}; + +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"); |
