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