1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Scalar fixed time AES core transform 4 * 5 * Copyright (C) 2017 Linaro Ltd <ard.biesheuvel@linaro.org> 6 */ 7 8 #include <crypto/aes.h> 9 #include <linux/crypto.h> 10 #include <linux/module.h> 11 12 static int aesti_set_key(struct crypto_tfm *tfm, const u8 *in_key, 13 unsigned int key_len) 14 { 15 struct crypto_aes_ctx *ctx = crypto_tfm_ctx(tfm); 16 17 return aes_expandkey(ctx, in_key, key_len); 18 } 19 20 static void aesti_encrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in) 21 { 22 const struct crypto_aes_ctx *ctx = crypto_tfm_ctx(tfm); 23 unsigned long flags; 24 25 /* 26 * Temporarily disable interrupts to avoid races where cachelines are 27 * evicted when the CPU is interrupted to do something else. 28 */ 29 local_irq_save(flags); 30 31 aes_encrypt(ctx, out, in); 32 33 local_irq_restore(flags); 34 } 35 36 static void aesti_decrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in) 37 { 38 const struct crypto_aes_ctx *ctx = crypto_tfm_ctx(tfm); 39 unsigned long flags; 40 41 /* 42 * Temporarily disable interrupts to avoid races where cachelines are 43 * evicted when the CPU is interrupted to do something else. 44 */ 45 local_irq_save(flags); 46 47 aes_decrypt(ctx, out, in); 48 49 local_irq_restore(flags); 50 } 51 52 static struct crypto_alg aes_alg = { 53 .cra_name = "aes", 54 .cra_driver_name = "aes-fixed-time", 55 .cra_priority = 100 + 1, 56 .cra_flags = CRYPTO_ALG_TYPE_CIPHER, 57 .cra_blocksize = AES_BLOCK_SIZE, 58 .cra_ctxsize = sizeof(struct crypto_aes_ctx), 59 .cra_module = THIS_MODULE, 60 61 .cra_cipher.cia_min_keysize = AES_MIN_KEY_SIZE, 62 .cra_cipher.cia_max_keysize = AES_MAX_KEY_SIZE, 63 .cra_cipher.cia_setkey = aesti_set_key, 64 .cra_cipher.cia_encrypt = aesti_encrypt, 65 .cra_cipher.cia_decrypt = aesti_decrypt 66 }; 67 68 static int __init aes_init(void) 69 { 70 return crypto_register_alg(&aes_alg); 71 } 72 73 static void __exit aes_fini(void) 74 { 75 crypto_unregister_alg(&aes_alg); 76 } 77 78 module_init(aes_init); 79 module_exit(aes_fini); 80 81 MODULE_DESCRIPTION("Generic fixed time AES"); 82 MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>"); 83 MODULE_LICENSE("GPL v2"); 84