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-rw-r--r--crypto/aes_ti.c83
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");