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eCryptfs: Use the ablkcipher crypto API
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Make the switch from the blkcipher kernel crypto interface to the
ablkcipher interface.

encrypt_scatterlist() and decrypt_scatterlist() now use the ablkcipher
interface but, from the eCryptfs standpoint, still treat the crypto
operation as a synchronous operation. They submit the async request and
then wait until the operation is finished before they return. Most of
the changes are contained inside those two functions.

Despite waiting for the completion of the crypto operation, the
ablkcipher interface provides performance increases in most cases when
used on AES-NI capable hardware.

Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
Acked-by: Colin King <colin.king@canonical.com>
Reviewed-by: Zeev Zilberman <zeev@annapurnaLabs.com>
Cc: Dustin Kirkland <dustin.kirkland@gazzang.com>
Cc: Tim Chen <tim.c.chen@intel.com>
Cc: Ying Huang <ying.huang@intel.com>
Cc: Thieu Le <thieule@google.com>
Cc: Li Wang <dragonylffly@163.com>
Cc: Jarkko Sakkinen <jarkko.sakkinen@iki.fi>
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Tyler Hicks committed May 9, 2013
1 parent c1be5a5 commit 4dfea4f
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Showing 2 changed files with 103 additions and 41 deletions.
141 changes: 101 additions & 40 deletions fs/ecryptfs/crypto.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -243,7 +243,7 @@ void ecryptfs_destroy_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat)
struct ecryptfs_key_sig *key_sig, *key_sig_tmp;

if (crypt_stat->tfm)
crypto_free_blkcipher(crypt_stat->tfm);
crypto_free_ablkcipher(crypt_stat->tfm);
if (crypt_stat->hash_tfm)
crypto_free_hash(crypt_stat->hash_tfm);
list_for_each_entry_safe(key_sig, key_sig_tmp,
Expand Down Expand Up @@ -319,6 +319,22 @@ int virt_to_scatterlist(const void *addr, int size, struct scatterlist *sg,
return i;
}

struct extent_crypt_result {
struct completion completion;
int rc;
};

static void extent_crypt_complete(struct crypto_async_request *req, int rc)
{
struct extent_crypt_result *ecr = req->data;

if (rc == -EINPROGRESS)
return;

ecr->rc = rc;
complete(&ecr->completion);
}

/**
* encrypt_scatterlist
* @crypt_stat: Pointer to the crypt_stat struct to initialize.
Expand All @@ -334,11 +350,8 @@ static int encrypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
struct scatterlist *src_sg, int size,
unsigned char *iv)
{
struct blkcipher_desc desc = {
.tfm = crypt_stat->tfm,
.info = iv,
.flags = CRYPTO_TFM_REQ_MAY_SLEEP
};
struct ablkcipher_request *req = NULL;
struct extent_crypt_result ecr;
int rc = 0;

BUG_ON(!crypt_stat || !crypt_stat->tfm
Expand All @@ -349,24 +362,47 @@ static int encrypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
ecryptfs_dump_hex(crypt_stat->key,
crypt_stat->key_size);
}
/* Consider doing this once, when the file is opened */

init_completion(&ecr.completion);

mutex_lock(&crypt_stat->cs_tfm_mutex);
if (!(crypt_stat->flags & ECRYPTFS_KEY_SET)) {
rc = crypto_blkcipher_setkey(crypt_stat->tfm, crypt_stat->key,
crypt_stat->key_size);
crypt_stat->flags |= ECRYPTFS_KEY_SET;
}
if (rc) {
ecryptfs_printk(KERN_ERR, "Error setting key; rc = [%d]\n",
rc);
req = ablkcipher_request_alloc(crypt_stat->tfm, GFP_NOFS);
if (!req) {
mutex_unlock(&crypt_stat->cs_tfm_mutex);
rc = -EINVAL;
rc = -ENOMEM;
goto out;
}
ecryptfs_printk(KERN_DEBUG, "Encrypting [%d] bytes.\n", size);
crypto_blkcipher_encrypt_iv(&desc, dest_sg, src_sg, size);

ablkcipher_request_set_callback(req,
CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
extent_crypt_complete, &ecr);
/* Consider doing this once, when the file is opened */
if (!(crypt_stat->flags & ECRYPTFS_KEY_SET)) {
rc = crypto_ablkcipher_setkey(crypt_stat->tfm, crypt_stat->key,
crypt_stat->key_size);
if (rc) {
ecryptfs_printk(KERN_ERR,
"Error setting key; rc = [%d]\n",
rc);
mutex_unlock(&crypt_stat->cs_tfm_mutex);
rc = -EINVAL;
goto out;
}
crypt_stat->flags |= ECRYPTFS_KEY_SET;
}
mutex_unlock(&crypt_stat->cs_tfm_mutex);
ecryptfs_printk(KERN_DEBUG, "Encrypting [%d] bytes.\n", size);
ablkcipher_request_set_crypt(req, src_sg, dest_sg, size, iv);
rc = crypto_ablkcipher_encrypt(req);
if (rc == -EINPROGRESS || rc == -EBUSY) {
struct extent_crypt_result *ecr = req->base.data;

wait_for_completion(&ecr->completion);
rc = ecr->rc;
INIT_COMPLETION(ecr->completion);
}
out:
ablkcipher_request_free(req);
return rc;
}

Expand Down Expand Up @@ -624,35 +660,61 @@ static int decrypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
struct scatterlist *src_sg, int size,
unsigned char *iv)
{
struct blkcipher_desc desc = {
.tfm = crypt_stat->tfm,
.info = iv,
.flags = CRYPTO_TFM_REQ_MAY_SLEEP
};
struct ablkcipher_request *req = NULL;
struct extent_crypt_result ecr;
int rc = 0;

/* Consider doing this once, when the file is opened */
BUG_ON(!crypt_stat || !crypt_stat->tfm
|| !(crypt_stat->flags & ECRYPTFS_STRUCT_INITIALIZED));
if (unlikely(ecryptfs_verbosity > 0)) {
ecryptfs_printk(KERN_DEBUG, "Key size [%zd]; key:\n",
crypt_stat->key_size);
ecryptfs_dump_hex(crypt_stat->key,
crypt_stat->key_size);
}

init_completion(&ecr.completion);

mutex_lock(&crypt_stat->cs_tfm_mutex);
rc = crypto_blkcipher_setkey(crypt_stat->tfm, crypt_stat->key,
crypt_stat->key_size);
if (rc) {
ecryptfs_printk(KERN_ERR, "Error setting key; rc = [%d]\n",
rc);
req = ablkcipher_request_alloc(crypt_stat->tfm, GFP_NOFS);
if (!req) {
mutex_unlock(&crypt_stat->cs_tfm_mutex);
rc = -EINVAL;
rc = -ENOMEM;
goto out;
}
ecryptfs_printk(KERN_DEBUG, "Decrypting [%d] bytes.\n", size);
rc = crypto_blkcipher_decrypt_iv(&desc, dest_sg, src_sg, size);

ablkcipher_request_set_callback(req,
CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
extent_crypt_complete, &ecr);
/* Consider doing this once, when the file is opened */
if (!(crypt_stat->flags & ECRYPTFS_KEY_SET)) {
rc = crypto_ablkcipher_setkey(crypt_stat->tfm, crypt_stat->key,
crypt_stat->key_size);
if (rc) {
ecryptfs_printk(KERN_ERR,
"Error setting key; rc = [%d]\n",
rc);
mutex_unlock(&crypt_stat->cs_tfm_mutex);
rc = -EINVAL;
goto out;
}
crypt_stat->flags |= ECRYPTFS_KEY_SET;
}
mutex_unlock(&crypt_stat->cs_tfm_mutex);
if (rc) {
ecryptfs_printk(KERN_ERR, "Error decrypting; rc = [%d]\n",
rc);
goto out;
ecryptfs_printk(KERN_DEBUG, "Decrypting [%d] bytes.\n", size);
ablkcipher_request_set_crypt(req, src_sg, dest_sg, size, iv);
rc = crypto_ablkcipher_decrypt(req);
if (rc == -EINPROGRESS || rc == -EBUSY) {
struct extent_crypt_result *ecr = req->base.data;

wait_for_completion(&ecr->completion);
rc = ecr->rc;
INIT_COMPLETION(ecr->completion);
}
rc = size;
out:
ablkcipher_request_free(req);
return rc;

}

/**
Expand Down Expand Up @@ -746,8 +808,7 @@ int ecryptfs_init_crypt_ctx(struct ecryptfs_crypt_stat *crypt_stat)
crypt_stat->cipher, "cbc");
if (rc)
goto out_unlock;
crypt_stat->tfm = crypto_alloc_blkcipher(full_alg_name, 0,
CRYPTO_ALG_ASYNC);
crypt_stat->tfm = crypto_alloc_ablkcipher(full_alg_name, 0, 0);
kfree(full_alg_name);
if (IS_ERR(crypt_stat->tfm)) {
rc = PTR_ERR(crypt_stat->tfm);
Expand All @@ -757,7 +818,7 @@ int ecryptfs_init_crypt_ctx(struct ecryptfs_crypt_stat *crypt_stat)
crypt_stat->cipher);
goto out_unlock;
}
crypto_blkcipher_set_flags(crypt_stat->tfm, CRYPTO_TFM_REQ_WEAK_KEY);
crypto_ablkcipher_set_flags(crypt_stat->tfm, CRYPTO_TFM_REQ_WEAK_KEY);
rc = 0;
out_unlock:
mutex_unlock(&crypt_stat->cs_tfm_mutex);
Expand Down
3 changes: 2 additions & 1 deletion fs/ecryptfs/ecryptfs_kernel.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -38,6 +38,7 @@
#include <linux/nsproxy.h>
#include <linux/backing-dev.h>
#include <linux/ecryptfs.h>
#include <linux/crypto.h>

#define ECRYPTFS_DEFAULT_IV_BYTES 16
#define ECRYPTFS_DEFAULT_EXTENT_SIZE 4096
Expand Down Expand Up @@ -233,7 +234,7 @@ struct ecryptfs_crypt_stat {
size_t extent_shift;
unsigned int extent_mask;
struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
struct crypto_blkcipher *tfm;
struct crypto_ablkcipher *tfm;
struct crypto_hash *hash_tfm; /* Crypto context for generating
* the initialization vectors */
unsigned char cipher[ECRYPTFS_MAX_CIPHER_NAME_SIZE];
Expand Down

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