linux_kernel/arch/arm/crypto/aesbs-glue.c

/*
 * linux/arch/arm/crypto/aesbs-glue.c - glue code for NEON bit sliced AES
 *
 * Copyright (C) 2013 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/neon.h>
#include <crypto/aes.h>
#include <crypto/cbc.h>
#include <crypto/internal/simd.h>
#include <crypto/internal/skcipher.h>
#include <linux/module.h>
#include <crypto/xts.h>

#include "aes_glue.h"

#define BIT_SLICED_KEY_MAXSIZE	(128 * (AES_MAXNR - 1) + 2 * AES_BLOCK_SIZE)

struct BS_KEY {
	struct AES_KEY	rk;
	int		converted;
	u8 __aligned(8)	bs[BIT_SLICED_KEY_MAXSIZE];
} __aligned(8);

asmlinkage void bsaes_enc_key_convert(u8 out[], struct AES_KEY const *in);
asmlinkage void bsaes_dec_key_convert(u8 out[], struct AES_KEY const *in);

asmlinkage void bsaes_cbc_encrypt(u8 const in[], u8 out[], u32 bytes,
				  struct BS_KEY *key, u8 iv[]);

asmlinkage void bsaes_ctr32_encrypt_blocks(u8 const in[], u8 out[], u32 blocks,
					   struct BS_KEY *key, u8 const iv[]);

asmlinkage void bsaes_xts_encrypt(u8 const in[], u8 out[], u32 bytes,
				  struct BS_KEY *key, u8 tweak[]);

asmlinkage void bsaes_xts_decrypt(u8 const in[], u8 out[], u32 bytes,
				  struct BS_KEY *key, u8 tweak[]);

struct aesbs_cbc_ctx {
	struct AES_KEY	enc;
	struct BS_KEY	dec;
};

struct aesbs_ctr_ctx {
	struct BS_KEY	enc;
};

struct aesbs_xts_ctx {
	struct BS_KEY	enc;
	struct BS_KEY	dec;
	struct AES_KEY	twkey;
};

static int aesbs_cbc_set_key(struct crypto_skcipher *tfm, const u8 *in_key,
			     unsigned int key_len)
{
	struct aesbs_cbc_ctx *ctx = crypto_skcipher_ctx(tfm);
	int bits = key_len * 8;

	if (private_AES_set_encrypt_key(in_key, bits, &ctx->enc)) {
		crypto_skcipher_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);
		return -EINVAL;
	}
	ctx->dec.rk = ctx->enc;
	private_AES_set_decrypt_key(in_key, bits, &ctx->dec.rk);
	ctx->dec.converted = 0;
	return 0;
}

static int aesbs_ctr_set_key(struct crypto_skcipher *tfm, const u8 *in_key,
			     unsigned int key_len)
{
	struct aesbs_ctr_ctx *ctx = crypto_skcipher_ctx(tfm);
	int bits = key_len * 8;

	if (private_AES_set_encrypt_key(in_key, bits, &ctx->enc.rk)) {
		crypto_skcipher_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);
		return -EINVAL;
	}
	ctx->enc.converted = 0;
	return 0;
}

static int aesbs_xts_set_key(struct crypto_skcipher *tfm, const u8 *in_key,
			     unsigned int key_len)
{
	struct aesbs_xts_ctx *ctx = crypto_skcipher_ctx(tfm);
	int bits = key_len * 4;
	int err;

	err = xts_verify_key(tfm, in_key, key_len);
	if (err)
		return err;

	if (private_AES_set_encrypt_key(in_key, bits, &ctx->enc.rk)) {
		crypto_skcipher_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);
		return -EINVAL;
	}
	ctx->dec.rk = ctx->enc.rk;
	private_AES_set_decrypt_key(in_key, bits, &ctx->dec.rk);
	private_AES_set_encrypt_key(in_key + key_len / 2, bits, &ctx->twkey);
	ctx->enc.converted = ctx->dec.converted = 0;
	return 0;
}

static inline void aesbs_encrypt_one(struct crypto_skcipher *tfm,
				     const u8 *src, u8 *dst)
{
	struct aesbs_cbc_ctx *ctx = crypto_skcipher_ctx(tfm);

	AES_encrypt(src, dst, &ctx->enc);
}

static int aesbs_cbc_encrypt(struct skcipher_request *req)
{
	return crypto_cbc_encrypt_walk(req, aesbs_encrypt_one);
}

static inline void aesbs_decrypt_one(struct crypto_skcipher *tfm,
				     const u8 *src, u8 *dst)
{
	struct aesbs_cbc_ctx *ctx = crypto_skcipher_ctx(tfm);

	AES_decrypt(src, dst, &ctx->dec.rk);
}

static int aesbs_cbc_decrypt(struct skcipher_request *req)
{
	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
	struct aesbs_cbc_ctx *ctx = crypto_skcipher_ctx(tfm);
	struct skcipher_walk walk;
	unsigned int nbytes;
	int err;

	for (err = skcipher_walk_virt(&walk, req, false);
	     (nbytes = walk.nbytes); err = skcipher_walk_done(&walk, nbytes)) {
		u32 blocks = nbytes / AES_BLOCK_SIZE;
		u8 *dst = walk.dst.virt.addr;
		u8 *src = walk.src.virt.addr;
		u8 *iv = walk.iv;

		if (blocks >= 8) {
			kernel_neon_begin();
			bsaes_cbc_encrypt(src, dst, nbytes, &ctx->dec, iv);
			kernel_neon_end();
			nbytes %= AES_BLOCK_SIZE;
			continue;
		}

		nbytes = crypto_cbc_decrypt_blocks(&walk, tfm,
						   aesbs_decrypt_one);
	}
	return err;
}

static void inc_be128_ctr(__be32 ctr[], u32 addend)
{
	int i;

	for (i = 3; i >= 0; i--, addend = 1) {
		u32 n = be32_to_cpu(ctr[i]) + addend;

		ctr[i] = cpu_to_be32(n);
		if (n >= addend)
			break;
	}
}

static int aesbs_ctr_encrypt(struct skcipher_request *req)
{
	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
	struct aesbs_ctr_ctx *ctx = crypto_skcipher_ctx(tfm);
	struct skcipher_walk walk;
	u32 blocks;
	int err;

	err = skcipher_walk_virt(&walk, req, false);

	while ((blocks = walk.nbytes / AES_BLOCK_SIZE)) {
		u32 tail = walk.nbytes % AES_BLOCK_SIZE;
		__be32 *ctr = (__be32 *)walk.iv;
		u32 headroom = UINT_MAX - be32_to_cpu(ctr[3]);

		/* avoid 32 bit counter overflow in the NEON code */
		if (unlikely(headroom < blocks)) {
			blocks = headroom + 1;
			tail = walk.nbytes - blocks * AES_BLOCK_SIZE;
		}
		kernel_neon_begin();
		bsaes_ctr32_encrypt_blocks(walk.src.virt.addr,
					   walk.dst.virt.addr, blocks,
					   &ctx->enc, walk.iv);
		kernel_neon_end();
		inc_be128_ctr(ctr, blocks);

		err = skcipher_walk_done(&walk, tail);
	}
	if (walk.nbytes) {
		u8 *tdst = walk.dst.virt.addr + blocks * AES_BLOCK_SIZE;
		u8 *tsrc = walk.src.virt.addr + blocks * AES_BLOCK_SIZE;
		u8 ks[AES_BLOCK_SIZE];

		AES_encrypt(walk.iv, ks, &ctx->enc.rk);
		if (tdst != tsrc)
			memcpy(tdst, tsrc, walk.nbytes);
		crypto_xor(tdst, ks, walk.nbytes);
		err = skcipher_walk_done(&walk, 0);
	}
	return err;
}

static int aesbs_xts_encrypt(struct skcipher_request *req)
{
	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
	struct aesbs_xts_ctx *ctx = crypto_skcipher_ctx(tfm);
	struct skcipher_walk walk;
	int err;

	err = skcipher_walk_virt(&walk, req, false);

	/* generate the initial tweak */
	AES_encrypt(walk.iv, walk.iv, &ctx->twkey);

	while (walk.nbytes) {
		kernel_neon_begin();
		bsaes_xts_encrypt(walk.src.virt.addr, walk.dst.virt.addr,
				  walk.nbytes, &ctx->enc, walk.iv);
		kernel_neon_end();
		err = skcipher_walk_done(&walk, walk.nbytes % AES_BLOCK_SIZE);
	}
	return err;
}

static int aesbs_xts_decrypt(struct skcipher_request *req)
{
	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
	struct aesbs_xts_ctx *ctx = crypto_skcipher_ctx(tfm);
	struct skcipher_walk walk;
	int err;

	err = skcipher_walk_virt(&walk, req, false);

	/* generate the initial tweak */
	AES_encrypt(walk.iv, walk.iv, &ctx->twkey);

	while (walk.nbytes) {
		kernel_neon_begin();
		bsaes_xts_decrypt(walk.src.virt.addr, walk.dst.virt.addr,
				  walk.nbytes, &ctx->dec, walk.iv);
		kernel_neon_end();
		err = skcipher_walk_done(&walk, walk.nbytes % AES_BLOCK_SIZE);
	}
	return err;
}

static struct skcipher_alg aesbs_algs[] = { {
	.base = {
		.cra_name		= "__cbc(aes)",
		.cra_driver_name	= "__cbc-aes-neonbs",
		.cra_priority		= 300,
		.cra_flags		= CRYPTO_ALG_INTERNAL,
		.cra_blocksize		= AES_BLOCK_SIZE,
		.cra_ctxsize		= sizeof(struct aesbs_cbc_ctx),
		.cra_alignmask		= 7,
		.cra_module		= THIS_MODULE,
	},
	.min_keysize	= AES_MIN_KEY_SIZE,
	.max_keysize	= AES_MAX_KEY_SIZE,
	.ivsize		= AES_BLOCK_SIZE,
	.setkey		= aesbs_cbc_set_key,
	.encrypt	= aesbs_cbc_encrypt,
	.decrypt	= aesbs_cbc_decrypt,
}, {
	.base = {
		.cra_name		= "__ctr(aes)",
		.cra_driver_name	= "__ctr-aes-neonbs",
		.cra_priority		= 300,
		.cra_flags		= CRYPTO_ALG_INTERNAL,
		.cra_blocksize		= 1,
		.cra_ctxsize		= sizeof(struct aesbs_ctr_ctx),
		.cra_alignmask		= 7,
		.cra_module		= THIS_MODULE,
	},
	.min_keysize	= AES_MIN_KEY_SIZE,
	.max_keysize	= AES_MAX_KEY_SIZE,
	.ivsize		= AES_BLOCK_SIZE,
	.chunksize	= AES_BLOCK_SIZE,
	.setkey		= aesbs_ctr_set_key,
	.encrypt	= aesbs_ctr_encrypt,
	.decrypt	= aesbs_ctr_encrypt,
}, {
	.base = {
		.cra_name		= "__xts(aes)",
		.cra_driver_name	= "__xts-aes-neonbs",
		.cra_priority		= 300,
		.cra_flags		= CRYPTO_ALG_INTERNAL,
		.cra_blocksize		= AES_BLOCK_SIZE,
		.cra_ctxsize		= sizeof(struct aesbs_xts_ctx),
		.cra_alignmask		= 7,
		.cra_module		= THIS_MODULE,
	},
	.min_keysize	= 2 * AES_MIN_KEY_SIZE,
	.max_keysize	= 2 * AES_MAX_KEY_SIZE,
	.ivsize		= AES_BLOCK_SIZE,
	.setkey		= aesbs_xts_set_key,
	.encrypt	= aesbs_xts_encrypt,
	.decrypt	= aesbs_xts_decrypt,
} };

struct simd_skcipher_alg *aesbs_simd_algs[ARRAY_SIZE(aesbs_algs)];

static void aesbs_mod_exit(void)
{
	int i;

	for (i = 0; i < ARRAY_SIZE(aesbs_simd_algs) && aesbs_simd_algs[i]; i++)
		simd_skcipher_free(aesbs_simd_algs[i]);

	crypto_unregister_skciphers(aesbs_algs, ARRAY_SIZE(aesbs_algs));
}

static int __init aesbs_mod_init(void)
{
	struct simd_skcipher_alg *simd;
	const char *basename;
	const char *algname;
	const char *drvname;
	int err;
	int i;

	if (!cpu_has_neon())
		return -ENODEV;

	err = crypto_register_skciphers(aesbs_algs, ARRAY_SIZE(aesbs_algs));
	if (err)
		return err;

	for (i = 0; i < ARRAY_SIZE(aesbs_algs); i++) {
		algname = aesbs_algs[i].base.cra_name + 2;
		drvname = aesbs_algs[i].base.cra_driver_name + 2;
		basename = aesbs_algs[i].base.cra_driver_name;
		simd = simd_skcipher_create_compat(algname, drvname, basename);
		err = PTR_ERR(simd);
		if (IS_ERR(simd))
			goto unregister_simds;

		aesbs_simd_algs[i] = simd;
	}

	return 0;

unregister_simds:
	aesbs_mod_exit();
	return err;
}

module_init(aesbs_mod_init);
module_exit(aesbs_mod_exit);

MODULE_DESCRIPTION("Bit sliced AES in CBC/CTR/XTS modes using NEON");
MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");
MODULE_LICENSE("GPL");