AES in CTR mode is used by modes such as GCM and CCM, which are often
used in contexts where only synchronous ciphers are permitted. So
provide a synchronous version of ctr(aes) based on the existing code.
This requires a non-SIMD fallback to deal with invocations occurring
from a context where SIMD instructions may not be used. We have a
helper for this now in the AES library, so wire that up.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
---
arch/arm/crypto/aes-neonbs-glue.c | 65 ++++++++++++++++++++
1 file changed, 65 insertions(+)
diff --git a/arch/arm/crypto/aes-neonbs-glue.c b/arch/arm/crypto/aes-neonbs-glue.c
index f43c9365b6a9..6eecdbb7e9b6 100644
--- a/arch/arm/crypto/aes-neonbs-glue.c
+++ b/arch/arm/crypto/aes-neonbs-glue.c
@@ -9,8 +9,10 @@
*/
#include <asm/neon.h>
+#include <asm/simd.h>
#include <crypto/aes.h>
#include <crypto/cbc.h>
+#include <crypto/ctr.h>
#include <crypto/internal/simd.h>
#include <crypto/internal/skcipher.h>
#include <crypto/xts.h>
@@ -57,6 +59,11 @@ struct aesbs_xts_ctx {
struct crypto_cipher *tweak_tfm;
};
+struct aesbs_ctr_ctx {
+ struct aesbs_ctx key; /* must be first member */
+ struct crypto_aes_ctx fallback;
+};
+
static int aesbs_setkey(struct crypto_skcipher *tfm, const u8 *in_key,
unsigned int key_len)
{
@@ -192,6 +199,25 @@ static void cbc_exit(struct crypto_tfm *tfm)
crypto_free_cipher(ctx->enc_tfm);
}
+static int aesbs_ctr_setkey_sync(struct crypto_skcipher *tfm, const u8 *in_key,
+ unsigned int key_len)
+{
+ struct aesbs_ctr_ctx *ctx = crypto_skcipher_ctx(tfm);
+ int err;
+
+ err = aes_expandkey(&ctx->fallback, in_key, key_len);
+ if (err)
+ return err;
+
+ ctx->key.rounds = 6 + key_len / 4;
+
+ kernel_neon_begin();
+ aesbs_convert_key(ctx->key.rk, ctx->fallback.key_enc, ctx->key.rounds);
+ kernel_neon_end();
+
+ return 0;
+}
+
static int ctr_encrypt(struct skcipher_request *req)
{
struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
@@ -234,6 +260,29 @@ static int ctr_encrypt(struct skcipher_request *req)
return err;
}
+static void ctr_encrypt_one(struct crypto_skcipher *tfm, const u8 *src, u8 *dst)
+{
+ struct aesbs_ctr_ctx *ctx = crypto_skcipher_ctx(tfm);
+ unsigned long flags;
+
+ /*
+ * Temporarily disable interrupts to avoid races where
+ * cachelines are evicted when the CPU is interrupted
+ * to do something else.
+ */
+ local_irq_save(flags);
+ aes_encrypt(&ctx->fallback, dst, src);
+ local_irq_restore(flags);
+}
+
+static int ctr_encrypt_sync(struct skcipher_request *req)
+{
+ if (!crypto_simd_usable())
+ return crypto_ctr_encrypt_walk(req, ctr_encrypt_one);
+
+ return ctr_encrypt(req);
+}
+
static int aesbs_xts_setkey(struct crypto_skcipher *tfm, const u8 *in_key,
unsigned int key_len)
{
@@ -361,6 +410,22 @@ static struct skcipher_alg aes_algs[] = { {
.setkey = aesbs_setkey,
.encrypt = ctr_encrypt,
.decrypt = ctr_encrypt,
+}, {
+ .base.cra_name = "ctr(aes)",
+ .base.cra_driver_name = "ctr-aes-neonbs-sync",
+ .base.cra_priority = 250 - 1,
+ .base.cra_blocksize = 1,
+ .base.cra_ctxsize = sizeof(struct aesbs_ctr_ctx),
+ .base.cra_module = THIS_MODULE,
+
+ .min_keysize = AES_MIN_KEY_SIZE,
+ .max_keysize = AES_MAX_KEY_SIZE,
+ .chunksize = AES_BLOCK_SIZE,
+ .walksize = 8 * AES_BLOCK_SIZE,
+ .ivsize = AES_BLOCK_SIZE,
+ .setkey = aesbs_ctr_setkey_sync,
+ .encrypt = ctr_encrypt_sync,
+ .decrypt = ctr_encrypt_sync,
}, {
.base.cra_name = "__xts(aes)",
.base.cra_driver_name = "__xts-aes-neonbs",
--
2.17.1
