[RFC,18/20] crypto: arm/aes-ce - provide a synchronous version of ctr(aes)

Commit Message

Ard Biesheuvel June 12, 2019, 12:48 p.m. UTC

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 <[e-mail]>
---
 arch/arm/crypto/aes-ce-glue.c | 36 ++++++++++++++++++++
 1 file changed, 36 insertions(+)

Patch

diff --git a/arch/arm/crypto/aes-ce-glue.c b/arch/arm/crypto/aes-ce-glue.c
index 04ba66903674..cdcc4b09e7db 100644
--- a/arch/arm/crypto/aes-ce-glue.c
+++ b/arch/arm/crypto/aes-ce-glue.c
@@ -10,6 +10,7 @@ 
 
 #include <asm/hwcap.h>
 #include <asm/neon.h>
+#include <asm/simd.h>
 #include <crypto/aes.h>
 #include <crypto/internal/simd.h>
 #include <crypto/internal/skcipher.h>
@@ -292,6 +293,23 @@  static int ctr_encrypt(struct skcipher_request *req)
 	return err;
 }
 
+static int ctr_encrypt_sync(struct skcipher_request *req)
+{
+	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
+	struct crypto_aes_ctx *ctx = crypto_skcipher_ctx(tfm);
+
+	if (!crypto_simd_usable()) {
+		struct skcipher_walk walk;
+		int err;
+
+		err = skcipher_walk_virt(&walk, req, true);
+		if (err)
+			return err;
+		return skcipher_encrypt_aes_ctr(&walk, ctx);
+	}
+	return ctr_encrypt(req);
+}
+
 static int xts_encrypt(struct skcipher_request *req)
 {
 	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
@@ -381,6 +399,21 @@  static struct skcipher_alg aes_algs[] = { {
 	.setkey			= ce_aes_setkey,
 	.encrypt		= ctr_encrypt,
 	.decrypt		= ctr_encrypt,
+}, {
+	.base.cra_name		= "ctr(aes)",
+	.base.cra_driver_name	= "ctr-aes-ce-sync",
+	.base.cra_priority	= 300 - 1,
+	.base.cra_blocksize	= 1,
+	.base.cra_ctxsize	= sizeof(struct crypto_aes_ctx),
+	.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			= ce_aes_setkey,
+	.encrypt		= ctr_encrypt_sync,
+	.decrypt		= ctr_encrypt_sync,
 }, {
 	.base.cra_name		= "__xts(aes)",
 	.base.cra_driver_name	= "__xts-aes-ce",
@@ -424,6 +457,9 @@  static int __init aes_init(void)
 		return err;
 
 	for (i = 0; i < ARRAY_SIZE(aes_algs); i++) {
+		if (!(aes_algs[i].base.cra_flags & CRYPTO_ALG_INTERNAL))
+			continue;
+
 		algname = aes_algs[i].base.cra_name + 2;
 		drvname = aes_algs[i].base.cra_driver_name + 2;
 		basename = aes_algs[i].base.cra_driver_name;