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1/**
2 * AES CTR 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#include "aesp8-ppc.h"
31
32struct p8_aes_ctr_ctx {
33 struct crypto_blkcipher *fallback;
34 struct aes_key enc_key;
35};
36
37static int p8_aes_ctr_init(struct crypto_tfm *tfm)
38{
39 const char *alg = crypto_tfm_alg_name(tfm);
40 struct crypto_blkcipher *fallback;
41 struct p8_aes_ctr_ctx *ctx = crypto_tfm_ctx(tfm);
42
43 fallback =
44 crypto_alloc_blkcipher(alg, 0, CRYPTO_ALG_NEED_FALLBACK);
45 if (IS_ERR(fallback)) {
46 printk(KERN_ERR
47 "Failed to allocate transformation for '%s': %ld\n",
48 alg, PTR_ERR(fallback));
49 return PTR_ERR(fallback);
50 }
51 printk(KERN_INFO "Using '%s' as fallback implementation.\n",
52 crypto_tfm_alg_driver_name((struct crypto_tfm *) fallback));
53
54 crypto_blkcipher_set_flags(
55 fallback,
56 crypto_blkcipher_get_flags((struct crypto_blkcipher *)tfm));
57 ctx->fallback = fallback;
58
59 return 0;
60}
61
62static void p8_aes_ctr_exit(struct crypto_tfm *tfm)
63{
64 struct p8_aes_ctr_ctx *ctx = crypto_tfm_ctx(tfm);
65
66 if (ctx->fallback) {
67 crypto_free_blkcipher(ctx->fallback);
68 ctx->fallback = NULL;
69 }
70}
71
72static int p8_aes_ctr_setkey(struct crypto_tfm *tfm, const u8 *key,
73 unsigned int keylen)
74{
75 int ret;
76 struct p8_aes_ctr_ctx *ctx = crypto_tfm_ctx(tfm);
77
78 preempt_disable();
79 pagefault_disable();
80 enable_kernel_vsx();
81 ret = aes_p8_set_encrypt_key(key, keylen * 8, &ctx->enc_key);
82 disable_kernel_vsx();
83 pagefault_enable();
84 preempt_enable();
85
86 ret += crypto_blkcipher_setkey(ctx->fallback, key, keylen);
87 return ret;
88}
89
90static void p8_aes_ctr_final(struct p8_aes_ctr_ctx *ctx,
91 struct blkcipher_walk *walk)
92{
93 u8 *ctrblk = walk->iv;
94 u8 keystream[AES_BLOCK_SIZE];
95 u8 *src = walk->src.virt.addr;
96 u8 *dst = walk->dst.virt.addr;
97 unsigned int nbytes = walk->nbytes;
98
99 preempt_disable();
100 pagefault_disable();
101 enable_kernel_vsx();
102 aes_p8_encrypt(ctrblk, keystream, &ctx->enc_key);
103 disable_kernel_vsx();
104 pagefault_enable();
105 preempt_enable();
106
107 crypto_xor(keystream, src, nbytes);
108 memcpy(dst, keystream, nbytes);
109 crypto_inc(ctrblk, AES_BLOCK_SIZE);
110}
111
112static int p8_aes_ctr_crypt(struct blkcipher_desc *desc,
113 struct scatterlist *dst,
114 struct scatterlist *src, unsigned int nbytes)
115{
116 int ret;
117 u64 inc;
118 struct blkcipher_walk walk;
119 struct p8_aes_ctr_ctx *ctx =
120 crypto_tfm_ctx(crypto_blkcipher_tfm(desc->tfm));
121 struct blkcipher_desc fallback_desc = {
122 .tfm = ctx->fallback,
123 .info = desc->info,
124 .flags = desc->flags
125 };
126
127 if (in_interrupt()) {
128 ret = crypto_blkcipher_encrypt(&fallback_desc, dst, src,
129 nbytes);
130 } else {
131 blkcipher_walk_init(&walk, dst, src, nbytes);
132 ret = blkcipher_walk_virt_block(desc, &walk, AES_BLOCK_SIZE);
133 while ((nbytes = walk.nbytes) >= AES_BLOCK_SIZE) {
134 preempt_disable();
135 pagefault_disable();
136 enable_kernel_vsx();
137 aes_p8_ctr32_encrypt_blocks(walk.src.virt.addr,
138 walk.dst.virt.addr,
139 (nbytes &
140 AES_BLOCK_MASK) /
141 AES_BLOCK_SIZE,
142 &ctx->enc_key,
143 walk.iv);
144 disable_kernel_vsx();
145 pagefault_enable();
146 preempt_enable();
147
148 /* We need to update IV mostly for last bytes/round */
149 inc = (nbytes & AES_BLOCK_MASK) / AES_BLOCK_SIZE;
150 if (inc > 0)
151 while (inc--)
152 crypto_inc(walk.iv, AES_BLOCK_SIZE);
153
154 nbytes &= AES_BLOCK_SIZE - 1;
155 ret = blkcipher_walk_done(desc, &walk, nbytes);
156 }
157 if (walk.nbytes) {
158 p8_aes_ctr_final(ctx, &walk);
159 ret = blkcipher_walk_done(desc, &walk, 0);
160 }
161 }
162
163 return ret;
164}
165
166struct crypto_alg p8_aes_ctr_alg = {
167 .cra_name = "ctr(aes)",
168 .cra_driver_name = "p8_aes_ctr",
169 .cra_module = THIS_MODULE,
170 .cra_priority = 2000,
171 .cra_type = &crypto_blkcipher_type,
172 .cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER | CRYPTO_ALG_NEED_FALLBACK,
173 .cra_alignmask = 0,
174 .cra_blocksize = 1,
175 .cra_ctxsize = sizeof(struct p8_aes_ctr_ctx),
176 .cra_init = p8_aes_ctr_init,
177 .cra_exit = p8_aes_ctr_exit,
178 .cra_blkcipher = {
179 .ivsize = AES_BLOCK_SIZE,
180 .min_keysize = AES_MIN_KEY_SIZE,
181 .max_keysize = AES_MAX_KEY_SIZE,
182 .setkey = p8_aes_ctr_setkey,
183 .encrypt = p8_aes_ctr_crypt,
184 .decrypt = p8_aes_ctr_crypt,
185 },
186};