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e59c1c9874
Take the existing small footprint and mostly time invariant C code and turn it into a AES library that can be used for non-performance critical, casual use of AES, and as a fallback for, e.g., SIMD code that needs a secondary path that can be taken in contexts where the SIMD unit is off limits (e.g., in hard interrupts taken from kernel context) Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
84 lines
2.0 KiB
C
84 lines
2.0 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Scalar fixed time AES core transform
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*
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* Copyright (C) 2017 Linaro Ltd <ard.biesheuvel@linaro.org>
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*/
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#include <crypto/aes.h>
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#include <linux/crypto.h>
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#include <linux/module.h>
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static int aesti_set_key(struct crypto_tfm *tfm, const u8 *in_key,
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unsigned int key_len)
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{
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struct crypto_aes_ctx *ctx = crypto_tfm_ctx(tfm);
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return aes_expandkey(ctx, in_key, key_len);
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}
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static void aesti_encrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
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{
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const struct crypto_aes_ctx *ctx = crypto_tfm_ctx(tfm);
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unsigned long flags;
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/*
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* Temporarily disable interrupts to avoid races where cachelines are
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* evicted when the CPU is interrupted to do something else.
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*/
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local_irq_save(flags);
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aes_encrypt(ctx, out, in);
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local_irq_restore(flags);
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}
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static void aesti_decrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
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{
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const struct crypto_aes_ctx *ctx = crypto_tfm_ctx(tfm);
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unsigned long flags;
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/*
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* Temporarily disable interrupts to avoid races where cachelines are
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* evicted when the CPU is interrupted to do something else.
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*/
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local_irq_save(flags);
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aes_decrypt(ctx, out, in);
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local_irq_restore(flags);
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}
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static struct crypto_alg aes_alg = {
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.cra_name = "aes",
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.cra_driver_name = "aes-fixed-time",
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.cra_priority = 100 + 1,
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.cra_flags = CRYPTO_ALG_TYPE_CIPHER,
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.cra_blocksize = AES_BLOCK_SIZE,
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.cra_ctxsize = sizeof(struct crypto_aes_ctx),
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.cra_module = THIS_MODULE,
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.cra_cipher.cia_min_keysize = AES_MIN_KEY_SIZE,
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.cra_cipher.cia_max_keysize = AES_MAX_KEY_SIZE,
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.cra_cipher.cia_setkey = aesti_set_key,
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.cra_cipher.cia_encrypt = aesti_encrypt,
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.cra_cipher.cia_decrypt = aesti_decrypt
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};
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static int __init aes_init(void)
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{
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return crypto_register_alg(&aes_alg);
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}
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static void __exit aes_fini(void)
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{
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crypto_unregister_alg(&aes_alg);
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}
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module_init(aes_init);
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module_exit(aes_fini);
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MODULE_DESCRIPTION("Generic fixed time AES");
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MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");
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MODULE_LICENSE("GPL v2");
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