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dm-crypt: switch to using the crc32 library

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Now that the crc32() library function takes advantage of
architecture-specific optimizations, it is unnecessary to go through the
crypto API.  Just use crc32().  This is much simpler, and it improves
performance due to eliminating the crypto API overhead.  (However, this
only affects the TCW IV mode of dm-crypt, which is a compatibility mode
that is rarely used compared to other dm-crypt modes.)

Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
This commit is contained in:
Eric Biggers
2025-01-27 14:15:33 -08:00
committed by Mikulas Patocka
parent 2014c95afe
commit f656fa4013
2 changed files with 11 additions and 31 deletions
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1
drivers/md/Kconfig
View File

@@ -267,6 +267,7 @@ config DM_CRYPT
depends on BLK_DEV_DM
depends on (ENCRYPTED_KEYS || ENCRYPTED_KEYS=n)
depends on (TRUSTED_KEYS || TRUSTED_KEYS=n)
select CRC32
select CRYPTO
select CRYPTO_CBC
select CRYPTO_ESSIV

41
drivers/md/dm-crypt.c
View File

@@ -17,6 +17,7 @@
#include <linux/bio.h>
#include <linux/blkdev.h>
#include <linux/blk-integrity.h>
#include <linux/crc32.h>
#include <linux/mempool.h>
#include <linux/slab.h>
#include <linux/crypto.h>
@@ -125,7 +126,6 @@ struct iv_lmk_private {
#define TCW_WHITENING_SIZE 16
struct iv_tcw_private {
struct crypto_shash *crc32_tfm;
u8 *iv_seed;
u8 *whitening;
};
@@ -607,10 +607,6 @@ static void crypt_iv_tcw_dtr(struct crypt_config *cc)
tcw->iv_seed = NULL;
kfree_sensitive(tcw->whitening);
tcw->whitening = NULL;
if (tcw->crc32_tfm && !IS_ERR(tcw->crc32_tfm))
crypto_free_shash(tcw->crc32_tfm);
tcw->crc32_tfm = NULL;
}
static int crypt_iv_tcw_ctr(struct crypt_config *cc, struct dm_target *ti,
@@ -628,13 +624,6 @@ static int crypt_iv_tcw_ctr(struct crypt_config *cc, struct dm_target *ti,
return -EINVAL;
}
tcw->crc32_tfm = crypto_alloc_shash("crc32", 0,
CRYPTO_ALG_ALLOCATES_MEMORY);
if (IS_ERR(tcw->crc32_tfm)) {
ti->error = "Error initializing CRC32 in TCW";
return PTR_ERR(tcw->crc32_tfm);
}
tcw->iv_seed = kzalloc(cc->iv_size, GFP_KERNEL);
tcw->whitening = kzalloc(TCW_WHITENING_SIZE, GFP_KERNEL);
if (!tcw->iv_seed || !tcw->whitening) {
@@ -668,36 +657,28 @@ static int crypt_iv_tcw_wipe(struct crypt_config *cc)
return 0;
}
static int crypt_iv_tcw_whitening(struct crypt_config *cc,
struct dm_crypt_request *dmreq,
u8 *data)
static void crypt_iv_tcw_whitening(struct crypt_config *cc,
struct dm_crypt_request *dmreq, u8 *data)
{
struct iv_tcw_private *tcw = &cc->iv_gen_private.tcw;
__le64 sector = cpu_to_le64(dmreq->iv_sector);
u8 buf[TCW_WHITENING_SIZE];
SHASH_DESC_ON_STACK(desc, tcw->crc32_tfm);
int i, r;
int i;
/* xor whitening with sector number */
crypto_xor_cpy(buf, tcw->whitening, (u8 *)&sector, 8);
crypto_xor_cpy(&buf[8], tcw->whitening + 8, (u8 *)&sector, 8);
/* calculate crc32 for every 32bit part and xor it */
desc->tfm = tcw->crc32_tfm;
for (i = 0; i < 4; i++) {
r = crypto_shash_digest(desc, &buf[i * 4], 4, &buf[i * 4]);
if (r)
goto out;
}
for (i = 0; i < 4; i++)
put_unaligned_le32(crc32(0, &buf[i * 4], 4), &buf[i * 4]);
crypto_xor(&buf[0], &buf[12], 4);
crypto_xor(&buf[4], &buf[8], 4);
/* apply whitening (8 bytes) to whole sector */
for (i = 0; i < ((1 << SECTOR_SHIFT) / 8); i++)
crypto_xor(data + i * 8, buf, 8);
out:
memzero_explicit(buf, sizeof(buf));
return r;
}
static int crypt_iv_tcw_gen(struct crypt_config *cc, u8 *iv,
@@ -707,13 +688,12 @@ static int crypt_iv_tcw_gen(struct crypt_config *cc, u8 *iv,
struct iv_tcw_private *tcw = &cc->iv_gen_private.tcw;
__le64 sector = cpu_to_le64(dmreq->iv_sector);
u8 *src;
int r = 0;
/* Remove whitening from ciphertext */
if (bio_data_dir(dmreq->ctx->bio_in) != WRITE) {
sg = crypt_get_sg_data(cc, dmreq->sg_in);
src = kmap_local_page(sg_page(sg));
r = crypt_iv_tcw_whitening(cc, dmreq, src + sg->offset);
crypt_iv_tcw_whitening(cc, dmreq, src + sg->offset);
kunmap_local(src);
}
@@ -723,7 +703,7 @@ static int crypt_iv_tcw_gen(struct crypt_config *cc, u8 *iv,
crypto_xor_cpy(&iv[8], tcw->iv_seed + 8, (u8 *)&sector,
cc->iv_size - 8);
return r;
return 0;
}
static int crypt_iv_tcw_post(struct crypt_config *cc, u8 *iv,
@@ -731,7 +711,6 @@ static int crypt_iv_tcw_post(struct crypt_config *cc, u8 *iv,
{
struct scatterlist *sg;
u8 *dst;
int r;
if (bio_data_dir(dmreq->ctx->bio_in) != WRITE)
return 0;
@@ -739,10 +718,10 @@ static int crypt_iv_tcw_post(struct crypt_config *cc, u8 *iv,
/* Apply whitening on ciphertext */
sg = crypt_get_sg_data(cc, dmreq->sg_out);
dst = kmap_local_page(sg_page(sg));
r = crypt_iv_tcw_whitening(cc, dmreq, dst + sg->offset);
crypt_iv_tcw_whitening(cc, dmreq, dst + sg->offset);
kunmap_local(dst);
return r;
return 0;
}
static int crypt_iv_random_gen(struct crypt_config *cc, u8 *iv,