arch/arm/crypto/aes-ce-glue.c

/*
 * aes-ce-glue.c - wrapper code for ARMv8 AES
 *
 * Copyright (C) 2015 Linaro Ltd <ard.biesheuvel@linaro.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <asm/hwcap.h>
#include <asm/neon.h>
#include <asm/hwcap.h>
#include <crypto/aes.h>
#include <crypto/ablk_helper.h>
#include <crypto/algapi.h>
#include <linux/module.h>
#include <crypto/xts.h>

MODULE_DESCRIPTION("AES-ECB/CBC/CTR/XTS using ARMv8 Crypto Extensions");
MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");
MODULE_LICENSE("GPL v2");

/* defined in aes-ce-core.S */
asmlinkage u32 ce_aes_sub(u32 input);
asmlinkage void ce_aes_invert(void *dst, void *src);

asmlinkage void ce_aes_ecb_encrypt(u8 out[], u8 const in[], u8 const rk[],
				   int rounds, int blocks);
asmlinkage void ce_aes_ecb_decrypt(u8 out[], u8 const in[], u8 const rk[],
				   int rounds, int blocks);

asmlinkage void ce_aes_cbc_encrypt(u8 out[], u8 const in[], u8 const rk[],
				   int rounds, int blocks, u8 iv[]);
asmlinkage void ce_aes_cbc_decrypt(u8 out[], u8 const in[], u8 const rk[],
				   int rounds, int blocks, u8 iv[]);

asmlinkage void ce_aes_ctr_encrypt(u8 out[], u8 const in[], u8 const rk[],
				   int rounds, int blocks, u8 ctr[]);

asmlinkage void ce_aes_xts_encrypt(u8 out[], u8 const in[], u8 const rk1[],
				   int rounds, int blocks, u8 iv[],
				   u8 const rk2[], int first);
asmlinkage void ce_aes_xts_decrypt(u8 out[], u8 const in[], u8 const rk1[],
				   int rounds, int blocks, u8 iv[],
				   u8 const rk2[], int first);

struct aes_block {
	u8 b[AES_BLOCK_SIZE];
};

static int num_rounds(struct crypto_aes_ctx *ctx)
{
	/*
	 * # of rounds specified by AES:
	 * 128 bit key		10 rounds
	 * 192 bit key		12 rounds
	 * 256 bit key		14 rounds
	 * => n byte key	=> 6 + (n/4) rounds
	 */
	return 6 + ctx->key_length / 4;
}

static int ce_aes_expandkey(struct crypto_aes_ctx *ctx, const u8 *in_key,
			    unsigned int key_len)
{
	/*
	 * The AES key schedule round constants
	 */
	static u8 const rcon[] = {
		0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36,
	};

	u32 kwords = key_len / sizeof(u32);
	struct aes_block *key_enc, *key_dec;
	int i, j;

	if (key_len != AES_KEYSIZE_128 &&
	    key_len != AES_KEYSIZE_192 &&
	    key_len != AES_KEYSIZE_256)
		return -EINVAL;

	memcpy(ctx->key_enc, in_key, key_len);
	ctx->key_length = key_len;

	kernel_neon_begin();
	for (i = 0; i < sizeof(rcon); i++) {
		u32 *rki = ctx->key_enc + (i * kwords);
		u32 *rko = rki + kwords;

		rko[0] = ror32(ce_aes_sub(rki[kwords - 1]), 8);
		rko[0] = rko[0] ^ rki[0] ^ rcon[i];
		rko[1] = rko[0] ^ rki[1];
		rko[2] = rko[1] ^ rki[2];
		rko[3] = rko[2] ^ rki[3];

		if (key_len == AES_KEYSIZE_192) {
			if (i >= 7)
				break;
			rko[4] = rko[3] ^ rki[4];
			rko[5] = rko[4] ^ rki[5];
		} else if (key_len == AES_KEYSIZE_256) {
			if (i >= 6)
				break;
			rko[4] = ce_aes_sub(rko[3]) ^ rki[4];
			rko[5] = rko[4] ^ rki[5];
			rko[6] = rko[5] ^ rki[6];
			rko[7] = rko[6] ^ rki[7];
		}
	}

	/*
	 * Generate the decryption keys for the Equivalent Inverse Cipher.
	 * This involves reversing the order of the round keys, and applying
	 * the Inverse Mix Columns transformation on all but the first and
	 * the last one.
	 */
	key_enc = (struct aes_block *)ctx->key_enc;
	key_dec = (struct aes_block *)ctx->key_dec;
	j = num_rounds(ctx);

	key_dec[0] = key_enc[j];
	for (i = 1, j--; j > 0; i++, j--)
		ce_aes_invert(key_dec + i, key_enc + j);
	key_dec[i] = key_enc[0];

	kernel_neon_end();
	return 0;
}

static int ce_aes_setkey(struct crypto_tfm *tfm, const u8 *in_key,
			 unsigned int key_len)
{
	struct crypto_aes_ctx *ctx = crypto_tfm_ctx(tfm);
	int ret;

	ret = ce_aes_expandkey(ctx, in_key, key_len);
	if (!ret)
		return 0;

	tfm->crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
	return -EINVAL;
}

struct crypto_aes_xts_ctx {
	struct crypto_aes_ctx key1;
	struct crypto_aes_ctx __aligned(8) key2;
};

static int xts_set_key(struct crypto_tfm *tfm, const u8 *in_key,
		       unsigned int key_len)
{
	struct crypto_aes_xts_ctx *ctx = crypto_tfm_ctx(tfm);
	int ret;

	ret = xts_check_key(tfm, in_key, key_len);
	if (ret)
		return ret;

	ret = ce_aes_expandkey(&ctx->key1, in_key, key_len / 2);
	if (!ret)
		ret = ce_aes_expandkey(&ctx->key2, &in_key[key_len / 2],
				       key_len / 2);
	if (!ret)
		return 0;

	tfm->crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
	return -EINVAL;
}

static int ecb_encrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
		       struct scatterlist *src, unsigned int nbytes)
{
	struct crypto_aes_ctx *ctx = crypto_blkcipher_ctx(desc->tfm);
	struct blkcipher_walk walk;
	unsigned int blocks;
	int err;

	desc->flags &= ~CRYPTO_TFM_REQ_MAY_SLEEP;
	blkcipher_walk_init(&walk, dst, src, nbytes);
	err = blkcipher_walk_virt(desc, &walk);

	kernel_neon_begin();
	while ((blocks = (walk.nbytes / AES_BLOCK_SIZE))) {
		ce_aes_ecb_encrypt(walk.dst.virt.addr, walk.src.virt.addr,
				   (u8 *)ctx->key_enc, num_rounds(ctx), blocks);
		err = blkcipher_walk_done(desc, &walk,
					  walk.nbytes % AES_BLOCK_SIZE);
	}
	kernel_neon_end();
	return err;
}

static int ecb_decrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
		       struct scatterlist *src, unsigned int nbytes)
{
	struct crypto_aes_ctx *ctx = crypto_blkcipher_ctx(desc->tfm);
	struct blkcipher_walk walk;
	unsigned int blocks;
	int err;

	desc->flags &= ~CRYPTO_TFM_REQ_MAY_SLEEP;
	blkcipher_walk_init(&walk, dst, src, nbytes);
	err = blkcipher_walk_virt(desc, &walk);

	kernel_neon_begin();
	while ((blocks = (walk.nbytes / AES_BLOCK_SIZE))) {
		ce_aes_ecb_decrypt(walk.dst.virt.addr, walk.src.virt.addr,
				   (u8 *)ctx->key_dec, num_rounds(ctx), blocks);
		err = blkcipher_walk_done(desc, &walk,
					  walk.nbytes % AES_BLOCK_SIZE);
	}
	kernel_neon_end();
	return err;
}

static int cbc_encrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
		       struct scatterlist *src, unsigned int nbytes)
{
	struct crypto_aes_ctx *ctx = crypto_blkcipher_ctx(desc->tfm);
	struct blkcipher_walk walk;
	unsigned int blocks;
	int err;

	desc->flags &= ~CRYPTO_TFM_REQ_MAY_SLEEP;
	blkcipher_walk_init(&walk, dst, src, nbytes);
	err = blkcipher_walk_virt(desc, &walk);

	kernel_neon_begin();
	while ((blocks = (walk.nbytes / AES_BLOCK_SIZE))) {
		ce_aes_cbc_encrypt(walk.dst.virt.addr, walk.src.virt.addr,
				   (u8 *)ctx->key_enc, num_rounds(ctx), blocks,
				   walk.iv);
		err = blkcipher_walk_done(desc, &walk,
					  walk.nbytes % AES_BLOCK_SIZE);
	}
	kernel_neon_end();
	return err;
}

static int cbc_decrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
		       struct scatterlist *src, unsigned int nbytes)
{
	struct crypto_aes_ctx *ctx = crypto_blkcipher_ctx(desc->tfm);
	struct blkcipher_walk walk;
	unsigned int blocks;
	int err;

	desc->flags &= ~CRYPTO_TFM_REQ_MAY_SLEEP;
	blkcipher_walk_init(&walk, dst, src, nbytes);
	err = blkcipher_walk_virt(desc, &walk);

	kernel_neon_begin();
	while ((blocks = (walk.nbytes / AES_BLOCK_SIZE))) {
		ce_aes_cbc_decrypt(walk.dst.virt.addr, walk.src.virt.addr,
				   (u8 *)ctx->key_dec, num_rounds(ctx), blocks,
				   walk.iv);
		err = blkcipher_walk_done(desc, &walk,
					  walk.nbytes % AES_BLOCK_SIZE);
	}
	kernel_neon_end();
	return err;
}

static int ctr_encrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
		       struct scatterlist *src, unsigned int nbytes)
{
	struct crypto_aes_ctx *ctx = crypto_blkcipher_ctx(desc->tfm);
	struct blkcipher_walk walk;
	int err, blocks;

	desc->flags &= ~CRYPTO_TFM_REQ_MAY_SLEEP;
	blkcipher_walk_init(&walk, dst, src, nbytes);
	err = blkcipher_walk_virt_block(desc, &walk, AES_BLOCK_SIZE);

	kernel_neon_begin();
	while ((blocks = (walk.nbytes / AES_BLOCK_SIZE))) {
		ce_aes_ctr_encrypt(walk.dst.virt.addr, walk.src.virt.addr,
				   (u8 *)ctx->key_enc, num_rounds(ctx), blocks,
				   walk.iv);
		nbytes -= blocks * AES_BLOCK_SIZE;
		if (nbytes && nbytes == walk.nbytes % AES_BLOCK_SIZE)
			break;
		err = blkcipher_walk_done(desc, &walk,
					  walk.nbytes % AES_BLOCK_SIZE);
	}
	if (nbytes) {
		u8 *tdst = walk.dst.virt.addr + blocks * AES_BLOCK_SIZE;
		u8 *tsrc = walk.src.virt.addr + blocks * AES_BLOCK_SIZE;
		u8 __aligned(8) tail[AES_BLOCK_SIZE];

		/*
		 * Minimum alignment is 8 bytes, so if nbytes is <= 8, we need
		 * to tell aes_ctr_encrypt() to only read half a block.
		 */
		blocks = (nbytes <= 8) ? -1 : 1;

		ce_aes_ctr_encrypt(tail, tsrc, (u8 *)ctx->key_enc,
				   num_rounds(ctx), blocks, walk.iv);
		memcpy(tdst, tail, nbytes);
		err = blkcipher_walk_done(desc, &walk, 0);
	}
	kernel_neon_end();

	return err;
}

static int xts_encrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
		       struct scatterlist *src, unsigned int nbytes)
{
	struct crypto_aes_xts_ctx *ctx = crypto_blkcipher_ctx(desc->tfm);
	int err, first, rounds = num_rounds(&ctx->key1);
	struct blkcipher_walk walk;
	unsigned int blocks;

	desc->flags &= ~CRYPTO_TFM_REQ_MAY_SLEEP;
	blkcipher_walk_init(&walk, dst, src, nbytes);
	err = blkcipher_walk_virt(desc, &walk);

	kernel_neon_begin();
	for (first = 1; (blocks = (walk.nbytes / AES_BLOCK_SIZE)); first = 0) {
		ce_aes_xts_encrypt(walk.dst.virt.addr, walk.src.virt.addr,
				   (u8 *)ctx->key1.key_enc, rounds, blocks,
				   walk.iv, (u8 *)ctx->key2.key_enc, first);
		err = blkcipher_walk_done(desc, &walk,
					  walk.nbytes % AES_BLOCK_SIZE);
	}
	kernel_neon_end();

	return err;
}

static int xts_decrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
		       struct scatterlist *src, unsigned int nbytes)
{
	struct crypto_aes_xts_ctx *ctx = crypto_blkcipher_ctx(desc->tfm);
	int err, first, rounds = num_rounds(&ctx->key1);
	struct blkcipher_walk walk;
	unsigned int blocks;

	desc->flags &= ~CRYPTO_TFM_REQ_MAY_SLEEP;
	blkcipher_walk_init(&walk, dst, src, nbytes);
	err = blkcipher_walk_virt(desc, &walk);

	kernel_neon_begin();
	for (first = 1; (blocks = (walk.nbytes / AES_BLOCK_SIZE)); first = 0) {
		ce_aes_xts_decrypt(walk.dst.virt.addr, walk.src.virt.addr,
				   (u8 *)ctx->key1.key_dec, rounds, blocks,
				   walk.iv, (u8 *)ctx->key2.key_enc, first);
		err = blkcipher_walk_done(desc, &walk,
					  walk.nbytes % AES_BLOCK_SIZE);
	}
	kernel_neon_end();

	return err;
}

static struct crypto_alg aes_algs[] = { {
	.cra_name		= "__ecb-aes-ce",
	.cra_driver_name	= "__driver-ecb-aes-ce",
	.cra_priority		= 0,
	.cra_flags		= CRYPTO_ALG_TYPE_BLKCIPHER |
				  CRYPTO_ALG_INTERNAL,
	.cra_blocksize		= AES_BLOCK_SIZE,
	.cra_ctxsize		= sizeof(struct crypto_aes_ctx),
	.cra_alignmask		= 7,
	.cra_type		= &crypto_blkcipher_type,
	.cra_module		= THIS_MODULE,
	.cra_blkcipher = {
		.min_keysize	= AES_MIN_KEY_SIZE,
		.max_keysize	= AES_MAX_KEY_SIZE,
		.ivsize		= 0,
		.setkey		= ce_aes_setkey,
		.encrypt	= ecb_encrypt,
		.decrypt	= ecb_decrypt,
	},
}, {
	.cra_name		= "__cbc-aes-ce",
	.cra_driver_name	= "__driver-cbc-aes-ce",
	.cra_priority		= 0,
	.cra_flags		= CRYPTO_ALG_TYPE_BLKCIPHER |
				  CRYPTO_ALG_INTERNAL,
	.cra_blocksize		= AES_BLOCK_SIZE,
	.cra_ctxsize		= sizeof(struct crypto_aes_ctx),
	.cra_alignmask		= 7,
	.cra_type		= &crypto_blkcipher_type,
	.cra_module		= THIS_MODULE,
	.cra_blkcipher = {
		.min_keysize	= AES_MIN_KEY_SIZE,
		.max_keysize	= AES_MAX_KEY_SIZE,
		.ivsize		= AES_BLOCK_SIZE,
		.setkey		= ce_aes_setkey,
		.encrypt	= cbc_encrypt,
		.decrypt	= cbc_decrypt,
	},
}, {
	.cra_name		= "__ctr-aes-ce",
	.cra_driver_name	= "__driver-ctr-aes-ce",
	.cra_priority		= 0,
	.cra_flags		= CRYPTO_ALG_TYPE_BLKCIPHER |
				  CRYPTO_ALG_INTERNAL,
	.cra_blocksize		= 1,
	.cra_ctxsize		= sizeof(struct crypto_aes_ctx),
	.cra_alignmask		= 7,
	.cra_type		= &crypto_blkcipher_type,
	.cra_module		= THIS_MODULE,
	.cra_blkcipher = {
		.min_keysize	= AES_MIN_KEY_SIZE,
		.max_keysize	= AES_MAX_KEY_SIZE,
		.ivsize		= AES_BLOCK_SIZE,
		.setkey		= ce_aes_setkey,
		.encrypt	= ctr_encrypt,
		.decrypt	= ctr_encrypt,
	},
}, {
	.cra_name		= "__xts-aes-ce",
	.cra_driver_name	= "__driver-xts-aes-ce",
	.cra_priority		= 0,
	.cra_flags		= CRYPTO_ALG_TYPE_BLKCIPHER |
				  CRYPTO_ALG_INTERNAL,
	.cra_blocksize		= AES_BLOCK_SIZE,
	.cra_ctxsize		= sizeof(struct crypto_aes_xts_ctx),
	.cra_alignmask		= 7,
	.cra_type		= &crypto_blkcipher_type,
	.cra_module		= THIS_MODULE,
	.cra_blkcipher = {
		.min_keysize	= 2 * AES_MIN_KEY_SIZE,
		.max_keysize	= 2 * AES_MAX_KEY_SIZE,
		.ivsize		= AES_BLOCK_SIZE,
		.setkey		= xts_set_key,
		.encrypt	= xts_encrypt,
		.decrypt	= xts_decrypt,
	},
}, {
	.cra_name		= "ecb(aes)",
	.cra_driver_name	= "ecb-aes-ce",
	.cra_priority		= 300,
	.cra_flags		= CRYPTO_ALG_TYPE_ABLKCIPHER|CRYPTO_ALG_ASYNC,
	.cra_blocksize		= AES_BLOCK_SIZE,
	.cra_ctxsize		= sizeof(struct async_helper_ctx),
	.cra_alignmask		= 7,
	.cra_type		= &crypto_ablkcipher_type,
	.cra_module		= THIS_MODULE,
	.cra_init		= ablk_init,
	.cra_exit		= ablk_exit,
	.cra_ablkcipher = {
		.min_keysize	= AES_MIN_KEY_SIZE,
		.max_keysize	= AES_MAX_KEY_SIZE,
		.ivsize		= 0,
		.setkey		= ablk_set_key,
		.encrypt	= ablk_encrypt,
		.decrypt	= ablk_decrypt,
	}
}, {
	.cra_name		= "cbc(aes)",
	.cra_driver_name	= "cbc-aes-ce",
	.cra_priority		= 300,
	.cra_flags		= CRYPTO_ALG_TYPE_ABLKCIPHER|CRYPTO_ALG_ASYNC,
	.cra_blocksize		= AES_BLOCK_SIZE,
	.cra_ctxsize		= sizeof(struct async_helper_ctx),
	.cra_alignmask		= 7,
	.cra_type		= &crypto_ablkcipher_type,
	.cra_module		= THIS_MODULE,
	.cra_init		= ablk_init,
	.cra_exit		= ablk_exit,
	.cra_ablkcipher = {
		.min_keysize	= AES_MIN_KEY_SIZE,
		.max_keysize	= AES_MAX_KEY_SIZE,
		.ivsize		= AES_BLOCK_SIZE,
		.setkey		= ablk_set_key,
		.encrypt	= ablk_encrypt,
		.decrypt	= ablk_decrypt,
	}
}, {
	.cra_name		= "ctr(aes)",
	.cra_driver_name	= "ctr-aes-ce",
	.cra_priority		= 300,
	.cra_flags		= CRYPTO_ALG_TYPE_ABLKCIPHER|CRYPTO_ALG_ASYNC,
	.cra_blocksize		= 1,
	.cra_ctxsize		= sizeof(struct async_helper_ctx),
	.cra_alignmask		= 7,
	.cra_type		= &crypto_ablkcipher_type,
	.cra_module		= THIS_MODULE,
	.cra_init		= ablk_init,
	.cra_exit		= ablk_exit,
	.cra_ablkcipher = {
		.min_keysize	= AES_MIN_KEY_SIZE,
		.max_keysize	= AES_MAX_KEY_SIZE,
		.ivsize		= AES_BLOCK_SIZE,
		.setkey		= ablk_set_key,
		.encrypt	= ablk_encrypt,
		.decrypt	= ablk_decrypt,
	}
}, {
	.cra_name		= "xts(aes)",
	.cra_driver_name	= "xts-aes-ce",
	.cra_priority		= 300,
	.cra_flags		= CRYPTO_ALG_TYPE_ABLKCIPHER|CRYPTO_ALG_ASYNC,
	.cra_blocksize		= AES_BLOCK_SIZE,
	.cra_ctxsize		= sizeof(struct async_helper_ctx),
	.cra_alignmask		= 7,
	.cra_type		= &crypto_ablkcipher_type,
	.cra_module		= THIS_MODULE,
	.cra_init		= ablk_init,
	.cra_exit		= ablk_exit,
	.cra_ablkcipher = {
		.min_keysize	= 2 * AES_MIN_KEY_SIZE,
		.max_keysize	= 2 * AES_MAX_KEY_SIZE,
		.ivsize		= AES_BLOCK_SIZE,
		.setkey		= ablk_set_key,
		.encrypt	= ablk_encrypt,
		.decrypt	= ablk_decrypt,
	}
} };

static int __init aes_init(void)
{
	if (!(elf_hwcap2 & HWCAP2_AES))
		return -ENODEV;
	return crypto_register_algs(aes_algs, ARRAY_SIZE(aes_algs));
}

static void __exit aes_exit(void)
{
	crypto_unregister_algs(aes_algs, ARRAY_SIZE(aes_algs));
}

module_init(aes_init);
module_exit(aes_exit);