1 files changed, 83 insertions, 0 deletions
diff --git a/crypto/aes_ti.c b/crypto/aes_ti.c
new file mode 100644
index 000000000..205c2c257
--- /dev/null
+++ b/crypto/aes_ti.c
@@ -0,0 +1,83 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Scalar fixed time AES core transform
+ *
+ * Copyright (C) 2017 Linaro Ltd <ard.biesheuvel@linaro.org>
+ */
+
+#include <crypto/aes.h>
+#include <linux/crypto.h>
+#include <linux/module.h>
+
+static int aesti_set_key(struct crypto_tfm *tfm, const u8 *in_key,
+			 unsigned int key_len)
+{
+	struct crypto_aes_ctx *ctx = crypto_tfm_ctx(tfm);
+
+	return aes_expandkey(ctx, in_key, key_len);
+}
+
+static void aesti_encrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
+{
+	const struct crypto_aes_ctx *ctx = crypto_tfm_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, out, in);
+
+	local_irq_restore(flags);
+}
+
+static void aesti_decrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
+{
+	const struct crypto_aes_ctx *ctx = crypto_tfm_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_decrypt(ctx, out, in);
+
+	local_irq_restore(flags);
+}
+
+static struct crypto_alg aes_alg = {
+	.cra_name			= "aes",
+	.cra_driver_name		= "aes-fixed-time",
+	.cra_priority			= 100 + 1,
+	.cra_flags			= CRYPTO_ALG_TYPE_CIPHER,
+	.cra_blocksize			= AES_BLOCK_SIZE,
+	.cra_ctxsize			= sizeof(struct crypto_aes_ctx),
+	.cra_module			= THIS_MODULE,
+
+	.cra_cipher.cia_min_keysize	= AES_MIN_KEY_SIZE,
+	.cra_cipher.cia_max_keysize	= AES_MAX_KEY_SIZE,
+	.cra_cipher.cia_setkey		= aesti_set_key,
+	.cra_cipher.cia_encrypt		= aesti_encrypt,
+	.cra_cipher.cia_decrypt		= aesti_decrypt
+};
+
+static int __init aes_init(void)
+{
+	return crypto_register_alg(&aes_alg);
+}
+
+static void __exit aes_fini(void)
+{
+	crypto_unregister_alg(&aes_alg);
+}
+
+module_init(aes_init);
+module_exit(aes_fini);
+
+MODULE_DESCRIPTION("Generic fixed time AES");
+MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");
+MODULE_LICENSE("GPL v2");