aes_xts.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * AES XTS routines supporting VMX In-core instructions on Power 8
  4 *
  5 * Copyright (C) 2015 International Business Machines Inc.
  6 *
  7 * Author: Leonidas S. Barbosa <leosilva@linux.vnet.ibm.com>
  8 */
  9
 10#include <asm/simd.h>
 11#include <asm/switch_to.h>
 12#include <crypto/aes.h>
 13#include <crypto/internal/simd.h>
 14#include <crypto/internal/skcipher.h>
 15#include <crypto/xts.h>
 16#include <linux/err.h>
 17#include <linux/kernel.h>
 18#include <linux/module.h>
 19#include <linux/uaccess.h>
 20
 21#include "aesp8-ppc.h"
 22
 23struct p8_aes_xts_ctx {
 24	struct crypto_skcipher *fallback;
 25	struct aes_key enc_key;
 26	struct aes_key dec_key;
 27	struct aes_key tweak_key;
 28};
 29
 30static int p8_aes_xts_init(struct crypto_skcipher *tfm)
 31{
 32	struct p8_aes_xts_ctx *ctx = crypto_skcipher_ctx(tfm);
 33	struct crypto_skcipher *fallback;
 34
 35	fallback = crypto_alloc_skcipher("xts(aes)", 0,
 36					 CRYPTO_ALG_NEED_FALLBACK |
 37					 CRYPTO_ALG_ASYNC);
 38	if (IS_ERR(fallback)) {
 39		pr_err("Failed to allocate xts(aes) fallback: %ld\n",
 40		       PTR_ERR(fallback));
 41		return PTR_ERR(fallback);
 42	}
 43
 44	crypto_skcipher_set_reqsize(tfm, sizeof(struct skcipher_request) +
 45				    crypto_skcipher_reqsize(fallback));
 46	ctx->fallback = fallback;
 47	return 0;
 48}
 49
 50static void p8_aes_xts_exit(struct crypto_skcipher *tfm)
 51{
 52	struct p8_aes_xts_ctx *ctx = crypto_skcipher_ctx(tfm);
 53
 54	crypto_free_skcipher(ctx->fallback);
 55}
 56
 57static int p8_aes_xts_setkey(struct crypto_skcipher *tfm, const u8 *key,
 58			     unsigned int keylen)
 59{
 60	struct p8_aes_xts_ctx *ctx = crypto_skcipher_ctx(tfm);
 61	int ret;
 62
 63	ret = xts_verify_key(tfm, key, keylen);
 64	if (ret)
 65		return ret;
 66
 67	preempt_disable();
 68	pagefault_disable();
 69	enable_kernel_vsx();
 70	ret = aes_p8_set_encrypt_key(key + keylen/2, (keylen/2) * 8, &ctx->tweak_key);
 71	ret |= aes_p8_set_encrypt_key(key, (keylen/2) * 8, &ctx->enc_key);
 72	ret |= aes_p8_set_decrypt_key(key, (keylen/2) * 8, &ctx->dec_key);
 73	disable_kernel_vsx();
 74	pagefault_enable();
 75	preempt_enable();
 76
 77	ret |= crypto_skcipher_setkey(ctx->fallback, key, keylen);
 78
 79	return ret ? -EINVAL : 0;
 80}
 81
 82static int p8_aes_xts_crypt(struct skcipher_request *req, int enc)
 83{
 84	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
 85	const struct p8_aes_xts_ctx *ctx = crypto_skcipher_ctx(tfm);
 86	struct skcipher_walk walk;
 87	unsigned int nbytes;
 88	u8 tweak[AES_BLOCK_SIZE];
 89	int ret;
 90
 91	if (req->cryptlen < AES_BLOCK_SIZE)
 92		return -EINVAL;
 93
 94	if (!crypto_simd_usable() || (req->cryptlen % XTS_BLOCK_SIZE) != 0) {
 95		struct skcipher_request *subreq = skcipher_request_ctx(req);
 96
 97		*subreq = *req;
 98		skcipher_request_set_tfm(subreq, ctx->fallback);
 99		return enc ? crypto_skcipher_encrypt(subreq) :
100			     crypto_skcipher_decrypt(subreq);
101	}
102
103	ret = skcipher_walk_virt(&walk, req, false);
104	if (ret)
105		return ret;
106
107	preempt_disable();
108	pagefault_disable();
109	enable_kernel_vsx();
110
111	aes_p8_encrypt(walk.iv, tweak, &ctx->tweak_key);
112
113	disable_kernel_vsx();
114	pagefault_enable();
115	preempt_enable();
116
117	while ((nbytes = walk.nbytes) != 0) {
118		preempt_disable();
119		pagefault_disable();
120		enable_kernel_vsx();
121		if (enc)
122			aes_p8_xts_encrypt(walk.src.virt.addr,
123					   walk.dst.virt.addr,
124					   round_down(nbytes, AES_BLOCK_SIZE),
125					   &ctx->enc_key, NULL, tweak);
126		else
127			aes_p8_xts_decrypt(walk.src.virt.addr,
128					   walk.dst.virt.addr,
129					   round_down(nbytes, AES_BLOCK_SIZE),
130					   &ctx->dec_key, NULL, tweak);
131		disable_kernel_vsx();
132		pagefault_enable();
133		preempt_enable();
134
135		ret = skcipher_walk_done(&walk, nbytes % AES_BLOCK_SIZE);
136	}
137	return ret;
138}
139
140static int p8_aes_xts_encrypt(struct skcipher_request *req)
141{
142	return p8_aes_xts_crypt(req, 1);
143}
144
145static int p8_aes_xts_decrypt(struct skcipher_request *req)
146{
147	return p8_aes_xts_crypt(req, 0);
148}
149
150struct skcipher_alg p8_aes_xts_alg = {
151	.base.cra_name = "xts(aes)",
152	.base.cra_driver_name = "p8_aes_xts",
153	.base.cra_module = THIS_MODULE,
154	.base.cra_priority = 2000,
155	.base.cra_flags = CRYPTO_ALG_NEED_FALLBACK,
156	.base.cra_blocksize = AES_BLOCK_SIZE,
157	.base.cra_ctxsize = sizeof(struct p8_aes_xts_ctx),
158	.setkey = p8_aes_xts_setkey,
159	.encrypt = p8_aes_xts_encrypt,
160	.decrypt = p8_aes_xts_decrypt,
161	.init = p8_aes_xts_init,
162	.exit = p8_aes_xts_exit,
163	.min_keysize = 2 * AES_MIN_KEY_SIZE,
164	.max_keysize = 2 * AES_MAX_KEY_SIZE,
165	.ivsize = AES_BLOCK_SIZE,
166};