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crypto: aes - Add CTR and XCTR support using library

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Implement the "ctr(aes)" and "xctr(aes)" crypto_skcipher algorithms
using the corresponding library functions.

Among other benefits, this allows the architecture-optimized AES-CTR and
AES-XCTR code to be migrated into the library while still leaving it
accessible via crypto_skcipher, eliminating lots of boilerplate code.

For now the cra_priority is set to just 110, since the
architecture-optimized implementations of these algorithms haven't yet
been migrated into the library.  It will be boosted once that happens.

Link: https://patch.msgid.link/20260715221153.246410-11-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
This commit is contained in:
Eric Biggers
2026-07-15 15:11:50 -07:00
parent 20df21a482
commit 747463a214
2 changed files with 69 additions and 0 deletions
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1
crypto/Kconfig
View File

@@ -360,6 +360,7 @@ config CRYPTO_AES
select CRYPTO_LIB_AES
select CRYPTO_LIB_AES_CBC if CRYPTO_CBC != n || CRYPTO_CTS != n
select CRYPTO_LIB_AES_CBC_MACS if CRYPTO_CMAC != n || CRYPTO_XCBC != n || CRYPTO_CCM != n
select CRYPTO_LIB_AES_CTR if CRYPTO_CTR != n || CRYPTO_XCTR != n
select CRYPTO_LIB_AES_ECB if CRYPTO_ECB != n
select CRYPTO_HASH if CRYPTO_CMAC != n || CRYPTO_XCBC != n || CRYPTO_CCM != n
# CRYPTO_SKCIPHER should be selected only if a mode that needs it is

68
crypto/aes.c
View File

@@ -7,6 +7,7 @@
#include <crypto/aes-cbc-macs.h>
#include <crypto/aes-cbc.h>
#include <crypto/aes-ctr.h>
#include <crypto/aes-ecb.h>
#include <crypto/aes.h>
#include <crypto/algapi.h>
@@ -456,6 +457,31 @@ crypto_aes_cbc_cts_decrypt(struct skcipher_request *req)
return crypto_aes_cbc_cts_crypt_nonlinear(req, /* enc= */ false);
}
/* AES-CTR */
static __maybe_unused int crypto_aes_ctr_crypt(struct skcipher_request *req)
{
const struct aes_enckey *key =
crypto_skcipher_ctx(crypto_skcipher_reqtfm(req));
AES_CRYPT_SG(aes_ctr, req->dst, req->src, req->cryptlen, 0, req->iv,
key);
return 0;
}
/* AES-XCTR */
static __maybe_unused int crypto_aes_xctr_crypt(struct skcipher_request *req)
{
const struct aes_enckey *key =
crypto_skcipher_ctx(crypto_skcipher_reqtfm(req));
u64 ctr = 1;
AES_CRYPT_SG(aes_xctr, req->dst, req->src, req->cryptlen, 0, &ctr,
req->iv, key);
return 0;
}
static struct skcipher_alg skcipher_algs[] = {
#if IS_ENABLED(CONFIG_CRYPTO_ECB)
{
@@ -504,6 +530,40 @@ static struct skcipher_alg skcipher_algs[] = {
.decrypt = crypto_aes_cbc_cts_decrypt,
},
#endif
#if IS_ENABLED(CONFIG_CRYPTO_CTR)
{
.base.cra_name = "ctr(aes)",
.base.cra_driver_name = "ctr-aes-lib",
.base.cra_priority = 110,
.base.cra_blocksize = 1,
.base.cra_ctxsize = sizeof(struct aes_enckey),
.base.cra_module = THIS_MODULE,
.min_keysize = AES_MIN_KEY_SIZE,
.max_keysize = AES_MAX_KEY_SIZE,
.ivsize = AES_BLOCK_SIZE,
.chunksize = AES_BLOCK_SIZE,
.setkey = crypto_aes_skcipher_setenckey,
.encrypt = crypto_aes_ctr_crypt,
.decrypt = crypto_aes_ctr_crypt,
},
#endif
#if IS_ENABLED(CONFIG_CRYPTO_XCTR)
{
.base.cra_name = "xctr(aes)",
.base.cra_driver_name = "xctr-aes-lib",
.base.cra_priority = 110,
.base.cra_blocksize = 1,
.base.cra_ctxsize = sizeof(struct aes_enckey),
.base.cra_module = THIS_MODULE,
.min_keysize = AES_MIN_KEY_SIZE,
.max_keysize = AES_MAX_KEY_SIZE,
.ivsize = AES_BLOCK_SIZE,
.chunksize = AES_BLOCK_SIZE,
.setkey = crypto_aes_skcipher_setenckey,
.encrypt = crypto_aes_xctr_crypt,
.decrypt = crypto_aes_xctr_crypt,
},
#endif
};
static int __init crypto_aes_mod_init(void)
@@ -576,3 +636,11 @@ MODULE_ALIAS_CRYPTO("cbc-aes-lib");
MODULE_ALIAS_CRYPTO("cts(cbc(aes))");
MODULE_ALIAS_CRYPTO("cts-cbc-aes-lib");
#endif
#if IS_ENABLED(CONFIG_CRYPTO_CTR)
MODULE_ALIAS_CRYPTO("ctr(aes)");
MODULE_ALIAS_CRYPTO("ctr-aes-lib");
#endif
#if IS_ENABLED(CONFIG_CRYPTO_XCTR)
MODULE_ALIAS_CRYPTO("xctr(aes)");
MODULE_ALIAS_CRYPTO("xctr-aes-lib");
#endif