linux/drivers/md/dm-crypt.c
Jens Axboe bb799ca020 bio: allow individual slabs in the bio_set
Instead of having a global bio slab cache, add a reference to one
in each bio_set that is created. This allows for personalized slabs
in each bio_set, so that they can have bios of different sizes.

This means we can personalize the bios we return. File systems may
want to embed the bio inside another structure, to avoid allocation
more items (and stuffing them in ->bi_private) after the get a bio.
Or we may want to embed a number of bio_vecs directly at the end
of a bio, to avoid doing two allocations to return a bio. This is now
possible.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
2008-12-29 08:29:23 +01:00

1338 lines
31 KiB
C

/*
* 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 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 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 = (struct dm_crypt_request *)((char *)req + cc->dmreq_start);
iv = (u8 *)ALIGN((unsigned long)(dmreq + 1),
crypto_ablkcipher_alignmask(cc->tfm) + 1);
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, 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;
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;
if (!atomic_dec_and_test(&io->pending))
return;
if (likely(!io->base_io))
bio_endio(io->base_bio, io->error);
else {
if (io->error && !io->base_io->error)
io->base_io->error = io->error;
crypt_dec_pending(io->base_io);
}
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;
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 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_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, 0);
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");