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eCryptfs: Combine encrypt_scatterlist() and decrypt_scatterlist()
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These two functions are identical except for a debug printk and whether
they call crypto_ablkcipher_encrypt() or crypto_ablkcipher_decrypt(), so
they can be safely merged if the caller can indicate if encryption or
decryption should occur.

The debug printk is useless so it is removed.

Two new #define's are created to indicate if an ENCRYPT or DECRYPT
operation is desired.

Signed-off-by: Tyler Hicks <[email protected]>
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@tyhicks
tyhicks committed Jun 8, 2013
1 parent 9c6043f commit 00a6994
Showing 1 changed file with 20 additions and 86 deletions.
106 changes: 20 additions & 86 deletions fs/ecryptfs/crypto.c
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Original file line number Diff line number Diff line change
Expand Up @@ -37,6 +37,9 @@
#include <asm/unaligned.h>
#include "ecryptfs_kernel.h"

#define DECRYPT 0
#define ENCRYPT 1

static int
ecryptfs_decrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
struct page *dst_page, struct page *src_page,
Expand Down Expand Up @@ -334,19 +337,20 @@ static void extent_crypt_complete(struct crypto_async_request *req, int rc)
}

/**
* encrypt_scatterlist
* crypt_scatterlist
* @crypt_stat: Pointer to the crypt_stat struct to initialize.
* @dest_sg: Destination of encrypted data
* @src_sg: Data to be encrypted
* @size: Length of data to be encrypted
* @iv: iv to use during encryption
* @dest_sg: Destination of the data after performing the crypto operation
* @src_sg: Data to be encrypted or decrypted
* @size: Length of data
* @iv: IV to use
* @op: ENCRYPT or DECRYPT to indicate the desired operation
*
* Returns the number of bytes encrypted; negative value on error
* Returns the number of bytes encrypted or decrypted; negative value on error
*/
static int encrypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
struct scatterlist *dest_sg,
struct scatterlist *src_sg, int size,
unsigned char *iv)
static int crypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
struct scatterlist *dest_sg,
struct scatterlist *src_sg, int size,
unsigned char *iv, int op)
{
struct ablkcipher_request *req = NULL;
struct extent_crypt_result ecr;
Expand Down Expand Up @@ -389,9 +393,9 @@ static int encrypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
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);
rc = op == ENCRYPT ? crypto_ablkcipher_encrypt(req) :
crypto_ablkcipher_decrypt(req);
if (rc == -EINPROGRESS || rc == -EBUSY) {
struct extent_crypt_result *ecr = req->base.data;

Expand Down Expand Up @@ -623,78 +627,6 @@ int ecryptfs_decrypt_page(struct page *page)
return rc;
}

/**
* decrypt_scatterlist
* @crypt_stat: Cryptographic context
* @dest_sg: The destination scatterlist to decrypt into
* @src_sg: The source scatterlist to decrypt from
* @size: The number of bytes to decrypt
* @iv: The initialization vector to use for the decryption
*
* Returns the number of bytes decrypted; negative value on error
*/
static int decrypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
struct scatterlist *dest_sg,
struct scatterlist *src_sg, int size,
unsigned char *iv)
{
struct ablkcipher_request *req = NULL;
struct extent_crypt_result ecr;
int rc = 0;

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);
req = ablkcipher_request_alloc(crypt_stat->tfm, GFP_NOFS);
if (!req) {
mutex_unlock(&crypt_stat->cs_tfm_mutex);
rc = -ENOMEM;
goto out;
}

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, "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);
}
out:
ablkcipher_request_free(req);
return rc;

}

/**
* ecryptfs_encrypt_page_offset
* @crypt_stat: The cryptographic context
Expand All @@ -718,7 +650,8 @@ ecryptfs_encrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,

sg_set_page(&src_sg, src_page, size, offset);
sg_set_page(&dst_sg, dst_page, size, offset);
return encrypt_scatterlist(crypt_stat, &dst_sg, &src_sg, size, iv);
return crypt_scatterlist(crypt_stat, &dst_sg, &src_sg,
size, iv, ENCRYPT);
}

/**
Expand All @@ -745,7 +678,8 @@ ecryptfs_decrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
sg_init_table(&dst_sg, 1);
sg_set_page(&dst_sg, dst_page, size, offset);

return decrypt_scatterlist(crypt_stat, &dst_sg, &src_sg, size, iv);
return crypt_scatterlist(crypt_stat, &dst_sg, &src_sg,
size, iv, DECRYPT);
}

#define ECRYPTFS_MAX_SCATTERLIST_LEN 4
Expand Down

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