Skip to content

Commit

Permalink
dm crypt: simplify crypt_ctr
Browse files Browse the repository at this point in the history 
Allocate cipher strings indpendently of struct crypt_config and move
cipher parsing and allocation into a separate function to prepare for
supporting the cryptoapi format e.g. "xts(aes)".

No functional change in this patch.

Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
  • Loading branch information
Milan Broz authored and Alasdair G Kergon committed Aug 12, 2010
1 parent 28513fc commit 5ebaee6
Showing 1 changed file with 104 additions and 81 deletions.
185 changes: 104 additions & 81 deletions drivers/md/dm-crypt.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -107,11 +107,10 @@ struct crypt_config {
struct workqueue_struct *io_queue;
struct workqueue_struct *crypt_queue;

/*
* crypto related data
*/
char *cipher;
char *cipher_mode;

struct crypt_iv_operations *iv_gen_ops;
char *iv_mode;
union {
struct iv_essiv_private essiv;
struct iv_benbi_private benbi;
Expand All @@ -135,8 +134,6 @@ struct crypt_config {
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;
Expand Down Expand Up @@ -1032,90 +1029,102 @@ static void crypt_dtr(struct dm_target *ti)
if (cc->dev)
dm_put_device(ti, cc->dev);

kfree(cc->iv_mode);
kzfree(cc->cipher);
kzfree(cc->cipher_mode);

/* Must zero key material before freeing */
kzfree(cc);
}

/*
* Construct an encryption mapping:
* <cipher> <key> <iv_offset> <dev_path> <start>
*/
static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
static int crypt_ctr_cipher(struct dm_target *ti,
char *cipher_in, char *key)
{
struct crypt_config *cc;
char *tmp;
char *cipher;
char *chainmode;
char *ivmode;
char *ivopts;
unsigned int key_size;
unsigned long long tmpll;
struct crypt_config *cc = ti->private;
char *tmp, *cipher, *chainmode, *ivmode, *ivopts;
char *cipher_api = NULL;
int ret = -EINVAL;

if (argc != 5) {
ti->error = "Not enough arguments";
/* Convert to crypto api definition? */
if (strchr(cipher_in, '(')) {
ti->error = "Bad cipher specification";
return -EINVAL;
}

tmp = argv[0];
/*
* Legacy dm-crypt cipher specification
* cipher-mode-iv:ivopts
*/
tmp = cipher_in;
cipher = strsep(&tmp, "-");

cc->cipher = kstrdup(cipher, GFP_KERNEL);
if (!cc->cipher)
goto bad_mem;

if (tmp) {
cc->cipher_mode = kstrdup(tmp, GFP_KERNEL);
if (!cc->cipher_mode)
goto bad_mem;
}

chainmode = strsep(&tmp, "-");
ivopts = strsep(&tmp, "-");
ivmode = strsep(&ivopts, ":");

if (tmp)
DMWARN("Unexpected additional cipher options");
DMWARN("Ignoring unexpected additional cipher options");

key_size = strlen(argv[1]) >> 1;

cc = kzalloc(sizeof(*cc) + key_size * sizeof(u8), GFP_KERNEL);
if (!cc) {
ti->error = "Cannot allocate transparent encryption context";
return -ENOMEM;
}

ti->private = cc;

/* Compatibility mode for old dm-crypt cipher strings */
if (!chainmode || (strcmp(chainmode, "plain") == 0 && !ivmode)) {
/* Compatibility mode for old dm-crypt mappings */
if (!chainmode || (!strcmp(chainmode, "plain") && !ivmode)) {
kfree(cc->cipher_mode);
cc->cipher_mode = kstrdup("cbc-plain", GFP_KERNEL);
chainmode = "cbc";
ivmode = "plain";
}

if (strcmp(chainmode, "ecb") && !ivmode) {
ti->error = "This chaining mode requires an IV mechanism";
goto bad;
ti->error = "IV mechanism required";
return -EINVAL;
}

ret = -ENOMEM;
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_api = kmalloc(CRYPTO_MAX_ALG_NAME, GFP_KERNEL);
if (!cipher_api)
goto bad_mem;

ret = snprintf(cipher_api, CRYPTO_MAX_ALG_NAME,
"%s(%s)", chainmode, cipher);
if (ret < 0) {
kfree(cipher_api);
goto bad_mem;
}

cc->tfm = crypto_alloc_ablkcipher(cc->cipher, 0, 0);
/* Allocate cipher */
cc->tfm = crypto_alloc_ablkcipher(cipher_api, 0, 0);
if (IS_ERR(cc->tfm)) {
ret = PTR_ERR(cc->tfm);
ti->error = "Error allocating crypto tfm";
goto bad;
}

strcpy(cc->cipher, cipher);
strcpy(cc->chainmode, chainmode);

ret = crypt_set_key(cc, argv[1]);
/* Initialize and set key */
ret = crypt_set_key(cc, key);
if (ret < 0) {
ti->error = "Error decoding and setting key";
goto bad;
}

/*
* Choose ivmode. Valid modes: "plain", "essiv:<esshash>", "benbi".
* See comments at iv code
*/
ret = -EINVAL;
/* Initialize IV */
cc->iv_size = crypto_ablkcipher_ivsize(cc->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 (ivmode) {
DMWARN("Selected cipher does not support IVs");
ivmode = NULL;
}

/* Choose ivmode, see comments at iv code. */
if (ivmode == NULL)
cc->iv_gen_ops = NULL;
else if (strcmp(ivmode, "plain") == 0)
Expand All @@ -1129,6 +1138,7 @@ static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
else if (strcmp(ivmode, "null") == 0)
cc->iv_gen_ops = &crypt_iv_null_ops;
else {
ret = -EINVAL;
ti->error = "Invalid IV mode";
goto bad;
}
Expand All @@ -1151,20 +1161,45 @@ static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
}
}

cc->iv_size = crypto_ablkcipher_ivsize(cc->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;
}
ret = 0;
bad:
kfree(cipher_api);
return ret;

bad_mem:
ti->error = "Cannot allocate cipher strings";
return -ENOMEM;
}

/*
* 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;
unsigned int key_size;
unsigned long long tmpll;
int ret;

if (argc != 5) {
ti->error = "Not enough arguments";
return -EINVAL;
}

key_size = strlen(argv[1]) >> 1;

cc = kzalloc(sizeof(*cc) + key_size * sizeof(u8), GFP_KERNEL);
if (!cc) {
ti->error = "Cannot allocate encryption context";
return -ENOMEM;
}

ti->private = cc;
ret = crypt_ctr_cipher(ti, argv[0], argv[1]);
if (ret < 0)
goto bad;

ret = -ENOMEM;
cc->io_pool = mempool_create_slab_pool(MIN_IOS, _crypt_io_pool);
if (!cc->io_pool) {
Expand Down Expand Up @@ -1217,17 +1252,6 @@ static int crypt_ctr(struct dm_target *ti, unsigned int argc, char **argv)
cc->start = tmpll;

ret = -ENOMEM;
if (ivmode && cc->iv_gen_ops) {
if (ivopts)
*(ivopts - 1) = ':';
cc->iv_mode = kstrdup(ivmode, GFP_KERNEL);
if (!cc->iv_mode) {
ti->error = "Error kmallocing iv_mode string";
goto bad;
}
} 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";
Expand Down Expand Up @@ -1273,7 +1297,7 @@ static int crypt_map(struct dm_target *ti, struct bio *bio,
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;
struct crypt_config *cc = ti->private;
unsigned int sz = 0;

switch (type) {
Expand All @@ -1282,11 +1306,10 @@ static int crypt_status(struct dm_target *ti, status_type_t type,
break;

case STATUSTYPE_TABLE:
if (cc->iv_mode)
DMEMIT("%s-%s-%s ", cc->cipher, cc->chainmode,
cc->iv_mode);
if (cc->cipher_mode)
DMEMIT("%s-%s ", cc->cipher, cc->cipher_mode);
else
DMEMIT("%s-%s ", cc->cipher, cc->chainmode);
DMEMIT("%s ", cc->cipher);

if (cc->key_size > 0) {
if ((maxlen - sz) < ((cc->key_size << 1) + 1))
Expand Down

0 comments on commit 5ebaee6

Please sign in to comment.