Linux-2.6.33.2/drivers/md/dm-crypt.c
/*
* Copyright (C) 2003 Christophe Saout <christophe@saout.de>
* Copyright (C) 2004 Clemens Fruhwirth <clemens@endorphin.org>
* Copyright (C) 2006-2009 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);
int (*init)(struct crypt_config *cc);
int (*wipe)(struct crypt_config *cc);
int (*generator)(struct crypt_config *cc, u8 *iv, sector_t sector);
};
struct iv_essiv_private {
struct crypto_cipher *tfm;
struct crypto_hash *hash_tfm;
u8 *salt;
};
struct iv_benbi_private {
int shift;
};
/*
* 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 iv_essiv_private essiv;
struct iv_benbi_private benbi;
} 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.
*
* plain64: the initial vector is the 64-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_plain64_gen(struct crypt_config *cc, u8 *iv,
sector_t sector)
{
memset(iv, 0, cc->iv_size);
*(u64 *)iv = cpu_to_le64(sector);
return 0;
}
/* Initialise ESSIV - compute salt but no local memory allocations */
static int crypt_iv_essiv_init(struct crypt_config *cc)
{
struct iv_essiv_private *essiv = &cc->iv_gen_private.essiv;
struct hash_desc desc;
struct scatterlist sg;
int err;
sg_init_one(&sg, cc->key, cc->key_size);
desc.tfm = essiv->hash_tfm;
desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;
err = crypto_hash_digest(&desc, &sg, cc->key_size, essiv->salt);
if (err)
return err;
return crypto_cipher_setkey(essiv->tfm, essiv->salt,
crypto_hash_digestsize(essiv->hash_tfm));
}
/* Wipe salt and reset key derived from volume key */
static int crypt_iv_essiv_wipe(struct crypt_config *cc)
{
struct iv_essiv_private *essiv = &cc->iv_gen_private.essiv;
unsigned salt_size = crypto_hash_digestsize(essiv->hash_tfm);
memset(essiv->salt, 0, salt_size);
return crypto_cipher_setkey(essiv->tfm, essiv->salt, salt_size);
}
static void crypt_iv_essiv_dtr(struct crypt_config *cc)
{
struct iv_essiv_private *essiv = &cc->iv_gen_private.essiv;
crypto_free_cipher(essiv->tfm);
essiv->tfm = NULL;
crypto_free_hash(essiv->hash_tfm);
essiv->hash_tfm = NULL;
kzfree(essiv->salt);
essiv->salt = NULL;
}
static int crypt_iv_essiv_ctr(struct crypt_config *cc, struct dm_target *ti,
const char *opts)
{
struct crypto_cipher *essiv_tfm = NULL;
struct crypto_hash *hash_tfm = NULL;
u8 *salt = NULL;
int err;
if (!opts) {
ti->error = "Digest algorithm missing for ESSIV mode";
return -EINVAL;
}
/* Allocate hash algorithm */
hash_tfm = crypto_alloc_hash(opts, 0, CRYPTO_ALG_ASYNC);
if (IS_ERR(hash_tfm)) {
ti->error = "Error initializing ESSIV hash";
err = PTR_ERR(hash_tfm);
goto bad;
}
salt = kzalloc(crypto_hash_digestsize(hash_tfm), GFP_KERNEL);
if (!salt) {
ti->error = "Error kmallocing salt storage in ESSIV";
err = -ENOMEM;
goto bad;
}
/* Allocate essiv_tfm */
essiv_tfm = crypto_alloc_cipher(cc->cipher, 0, CRYPTO_ALG_ASYNC);
if (IS_ERR(essiv_tfm)) {
ti->error = "Error allocating crypto tfm for ESSIV";
err = PTR_ERR(essiv_tfm);
goto bad;
}
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";
err = -EINVAL;
goto bad;
}
cc->iv_gen_private.essiv.salt = salt;
cc->iv_gen_private.essiv.tfm = essiv_tfm;
cc->iv_gen_private.essiv.hash_tfm = hash_tfm;
return 0;
bad:
if (essiv_tfm && !IS_ERR(essiv_tfm))
crypto_free_cipher(essiv_tfm);
if (hash_tfm && !IS_ERR(hash_tfm))
crypto_free_hash(hash_tfm);
kfree(salt);
return err;
}
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_plain64_ops = {
.generator = crypt_iv_plain64_gen
};
static struct crypt_iv_operations crypt_iv_essiv_ops = {
.ctr = crypt_iv_essiv_ctr,
.dtr = crypt_iv_essiv_dtr,
.init = crypt_iv_essiv_init,
.wipe = crypt_iv_essiv_wipe,
.generator = crypt_iv_essiv_gen
};
static 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(BLK_RW_ASYNC, 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 crypto_ablkcipher_setkey(cc->tfm, cc->key, cc->key_size);
}
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 crypto_ablkcipher_setkey(cc->tfm, cc->key, cc->key_size);
}
/*
* 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;
}
/* Compatibility 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;
if (crypt_set_key(cc, argv[1]) < 0) {
ti->error = "Error decoding and setting key";
goto bad_ivmode;
}
/*
* 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, "plain64") == 0)
cc->iv_gen_ops = &crypt_iv_plain64_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;
if (cc->iv_gen_ops && cc->iv_gen_ops->init &&
cc->iv_gen_ops->init(cc) < 0) {
ti->error = "Error initialising IV";
goto bad_slab_pool;
}
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, 0);
if (!cc->bs) {
ti->error = "Cannot allocate crypt bioset";
goto bad_bs;
}
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->num_flush_requests = 1;
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 */
kzfree(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 */
kzfree(cc);
}
static int crypt_map(struct dm_target *ti, struct bio *bio,
union map_info *map_context)
{
struct dm_crypt_io *io;
struct crypt_config *cc;
if (unlikely(bio_empty_barrier(bio))) {
cc = ti->private;
bio->bi_bdev = cc->dev->bdev;
return DM_MAPIO_REMAPPED;
}
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;
int ret = -EINVAL;
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"))) {
ret = crypt_set_key(cc, argv[2]);
if (ret)
return ret;
if (cc->iv_gen_ops && cc->iv_gen_ops->init)
ret = cc->iv_gen_ops->init(cc);
return ret;
}
if (argc == 2 && !strnicmp(argv[1], MESG_STR("wipe"))) {
if (cc->iv_gen_ops && cc->iv_gen_ops->wipe) {
ret = cc->iv_gen_ops->wipe(cc);
if (ret)
return ret;
}
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 int crypt_iterate_devices(struct dm_target *ti,
iterate_devices_callout_fn fn, void *data)
{
struct crypt_config *cc = ti->private;
return fn(ti, cc->dev, cc->start, ti->len, data);
}
static struct target_type crypt_target = {
.name = "crypt",
.version = {1, 7, 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,
.iterate_devices = crypt_iterate_devices,
};
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)
{
dm_unregister_target(&crypt_target);
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");