1/**
2 * AES CBC routines supporting VMX instructions on the Power 8
3 *
4 * Copyright (C) 2015 International Business Machines Inc.
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; version 2 only.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
18 *
19 * Author: Marcelo Henrique Cerri <mhcerri@br.ibm.com>
20 */
21
22#include <linux/types.h>
23#include <linux/err.h>
24#include <linux/crypto.h>
25#include <linux/delay.h>
26#include <linux/hardirq.h>
27#include <asm/switch_to.h>
28#include <crypto/aes.h>
29#include <crypto/scatterwalk.h>
30
31#include "aesp8-ppc.h"
32
33struct p8_aes_cbc_ctx {
34	struct crypto_blkcipher *fallback;
35	struct aes_key enc_key;
36	struct aes_key dec_key;
37};
38
39static int p8_aes_cbc_init(struct crypto_tfm *tfm)
40{
41	const char *alg;
42	struct crypto_blkcipher *fallback;
43	struct p8_aes_cbc_ctx *ctx = crypto_tfm_ctx(tfm);
44
45	if (!(alg = crypto_tfm_alg_name(tfm))) {
46		printk(KERN_ERR "Failed to get algorithm name.\n");
47		return -ENOENT;
48	}
49
50	fallback =
51	    crypto_alloc_blkcipher(alg, 0, CRYPTO_ALG_NEED_FALLBACK);
52	if (IS_ERR(fallback)) {
53		printk(KERN_ERR
54		       "Failed to allocate transformation for '%s': %ld\n",
55		       alg, PTR_ERR(fallback));
56		return PTR_ERR(fallback);
57	}
58	printk(KERN_INFO "Using '%s' as fallback implementation.\n",
59	       crypto_tfm_alg_driver_name((struct crypto_tfm *) fallback));
60
61	crypto_blkcipher_set_flags(
62		fallback,
63		crypto_blkcipher_get_flags((struct crypto_blkcipher *)tfm));
64	ctx->fallback = fallback;
65
66	return 0;
67}
68
69static void p8_aes_cbc_exit(struct crypto_tfm *tfm)
70{
71	struct p8_aes_cbc_ctx *ctx = crypto_tfm_ctx(tfm);
72
73	if (ctx->fallback) {
74		crypto_free_blkcipher(ctx->fallback);
75		ctx->fallback = NULL;
76	}
77}
78
79static int p8_aes_cbc_setkey(struct crypto_tfm *tfm, const u8 *key,
80			     unsigned int keylen)
81{
82	int ret;
83	struct p8_aes_cbc_ctx *ctx = crypto_tfm_ctx(tfm);
84
85	preempt_disable();
86	pagefault_disable();
87	enable_kernel_altivec();
88	enable_kernel_vsx();
89	ret = aes_p8_set_encrypt_key(key, keylen * 8, &ctx->enc_key);
90	ret += aes_p8_set_decrypt_key(key, keylen * 8, &ctx->dec_key);
91	pagefault_enable();
92	preempt_enable();
93
94	ret += crypto_blkcipher_setkey(ctx->fallback, key, keylen);
95	return ret;
96}
97
98static int p8_aes_cbc_encrypt(struct blkcipher_desc *desc,
99			      struct scatterlist *dst,
100			      struct scatterlist *src, unsigned int nbytes)
101{
102	int ret;
103	struct blkcipher_walk walk;
104	struct p8_aes_cbc_ctx *ctx =
105		crypto_tfm_ctx(crypto_blkcipher_tfm(desc->tfm));
106	struct blkcipher_desc fallback_desc = {
107		.tfm = ctx->fallback,
108		.info = desc->info,
109		.flags = desc->flags
110	};
111
112	if (in_interrupt()) {
113		ret = crypto_blkcipher_encrypt(&fallback_desc, dst, src,
114					       nbytes);
115	} else {
116		preempt_disable();
117		pagefault_disable();
118		enable_kernel_altivec();
119		enable_kernel_vsx();
120
121		blkcipher_walk_init(&walk, dst, src, nbytes);
122		ret = blkcipher_walk_virt(desc, &walk);
123		while ((nbytes = walk.nbytes)) {
124			aes_p8_cbc_encrypt(walk.src.virt.addr,
125					   walk.dst.virt.addr,
126					   nbytes & AES_BLOCK_MASK,
127					   &ctx->enc_key, walk.iv, 1);
128			nbytes &= AES_BLOCK_SIZE - 1;
129			ret = blkcipher_walk_done(desc, &walk, nbytes);
130		}
131
132		pagefault_enable();
133		preempt_enable();
134	}
135
136	return ret;
137}
138
139static int p8_aes_cbc_decrypt(struct blkcipher_desc *desc,
140			      struct scatterlist *dst,
141			      struct scatterlist *src, unsigned int nbytes)
142{
143	int ret;
144	struct blkcipher_walk walk;
145	struct p8_aes_cbc_ctx *ctx =
146		crypto_tfm_ctx(crypto_blkcipher_tfm(desc->tfm));
147	struct blkcipher_desc fallback_desc = {
148		.tfm = ctx->fallback,
149		.info = desc->info,
150		.flags = desc->flags
151	};
152
153	if (in_interrupt()) {
154		ret = crypto_blkcipher_decrypt(&fallback_desc, dst, src,
155					       nbytes);
156	} else {
157		preempt_disable();
158		pagefault_disable();
159		enable_kernel_altivec();
160		enable_kernel_vsx();
161
162		blkcipher_walk_init(&walk, dst, src, nbytes);
163		ret = blkcipher_walk_virt(desc, &walk);
164		while ((nbytes = walk.nbytes)) {
165			aes_p8_cbc_encrypt(walk.src.virt.addr,
166					   walk.dst.virt.addr,
167					   nbytes & AES_BLOCK_MASK,
168					   &ctx->dec_key, walk.iv, 0);
169			nbytes &= AES_BLOCK_SIZE - 1;
170			ret = blkcipher_walk_done(desc, &walk, nbytes);
171		}
172
173		pagefault_enable();
174		preempt_enable();
175	}
176
177	return ret;
178}
179
180
181struct crypto_alg p8_aes_cbc_alg = {
182	.cra_name = "cbc(aes)",
183	.cra_driver_name = "p8_aes_cbc",
184	.cra_module = THIS_MODULE,
185	.cra_priority = 1000,
186	.cra_type = &crypto_blkcipher_type,
187	.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER | CRYPTO_ALG_NEED_FALLBACK,
188	.cra_alignmask = 0,
189	.cra_blocksize = AES_BLOCK_SIZE,
190	.cra_ctxsize = sizeof(struct p8_aes_cbc_ctx),
191	.cra_init = p8_aes_cbc_init,
192	.cra_exit = p8_aes_cbc_exit,
193	.cra_blkcipher = {
194			  .ivsize = 0,
195			  .min_keysize = AES_MIN_KEY_SIZE,
196			  .max_keysize = AES_MAX_KEY_SIZE,
197			  .setkey = p8_aes_cbc_setkey,
198			  .encrypt = p8_aes_cbc_encrypt,
199			  .decrypt = p8_aes_cbc_decrypt,
200	},
201};
202