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
32 struct p8_aes_ctr_ctx {
33 struct crypto_blkcipher *fallback;
34 struct aes_key enc_key;
35 };
36
p8_aes_ctr_init(struct crypto_tfm * tfm)37 static int p8_aes_ctr_init(struct crypto_tfm *tfm)
38 {
39 const char *alg;
40 struct crypto_blkcipher *fallback;
41 struct p8_aes_ctr_ctx *ctx = crypto_tfm_ctx(tfm);
42
43 if (!(alg = crypto_tfm_alg_name(tfm))) {
44 printk(KERN_ERR "Failed to get algorithm name.\n");
45 return -ENOENT;
46 }
47
48 fallback =
49 crypto_alloc_blkcipher(alg, 0, CRYPTO_ALG_NEED_FALLBACK);
50 if (IS_ERR(fallback)) {
51 printk(KERN_ERR
52 "Failed to allocate transformation for '%s': %ld\n",
53 alg, PTR_ERR(fallback));
54 return PTR_ERR(fallback);
55 }
56
57 crypto_blkcipher_set_flags(
58 fallback,
59 crypto_blkcipher_get_flags((struct crypto_blkcipher *)tfm));
60 ctx->fallback = fallback;
61
62 return 0;
63 }
64
p8_aes_ctr_exit(struct crypto_tfm * tfm)65 static void p8_aes_ctr_exit(struct crypto_tfm *tfm)
66 {
67 struct p8_aes_ctr_ctx *ctx = crypto_tfm_ctx(tfm);
68
69 if (ctx->fallback) {
70 crypto_free_blkcipher(ctx->fallback);
71 ctx->fallback = NULL;
72 }
73 }
74
p8_aes_ctr_setkey(struct crypto_tfm * tfm,const u8 * key,unsigned int keylen)75 static int p8_aes_ctr_setkey(struct crypto_tfm *tfm, const u8 *key,
76 unsigned int keylen)
77 {
78 int ret;
79 struct p8_aes_ctr_ctx *ctx = crypto_tfm_ctx(tfm);
80
81 preempt_disable();
82 pagefault_disable();
83 enable_kernel_altivec();
84 enable_kernel_vsx();
85 ret = aes_p8_set_encrypt_key(key, keylen * 8, &ctx->enc_key);
86 pagefault_enable();
87 preempt_enable();
88
89 ret += crypto_blkcipher_setkey(ctx->fallback, key, keylen);
90 return ret;
91 }
92
p8_aes_ctr_final(struct p8_aes_ctr_ctx * ctx,struct blkcipher_walk * walk)93 static void p8_aes_ctr_final(struct p8_aes_ctr_ctx *ctx,
94 struct blkcipher_walk *walk)
95 {
96 u8 *ctrblk = walk->iv;
97 u8 keystream[AES_BLOCK_SIZE];
98 u8 *src = walk->src.virt.addr;
99 u8 *dst = walk->dst.virt.addr;
100 unsigned int nbytes = walk->nbytes;
101
102 preempt_disable();
103 pagefault_disable();
104 enable_kernel_altivec();
105 enable_kernel_vsx();
106 aes_p8_encrypt(ctrblk, keystream, &ctx->enc_key);
107 pagefault_enable();
108 preempt_enable();
109
110 crypto_xor(keystream, src, nbytes);
111 memcpy(dst, keystream, nbytes);
112 crypto_inc(ctrblk, AES_BLOCK_SIZE);
113 }
114
p8_aes_ctr_crypt(struct blkcipher_desc * desc,struct scatterlist * dst,struct scatterlist * src,unsigned int nbytes)115 static int p8_aes_ctr_crypt(struct blkcipher_desc *desc,
116 struct scatterlist *dst,
117 struct scatterlist *src, unsigned int nbytes)
118 {
119 int ret;
120 u64 inc;
121 struct blkcipher_walk walk;
122 struct p8_aes_ctr_ctx *ctx =
123 crypto_tfm_ctx(crypto_blkcipher_tfm(desc->tfm));
124 struct blkcipher_desc fallback_desc = {
125 .tfm = ctx->fallback,
126 .info = desc->info,
127 .flags = desc->flags
128 };
129
130 if (in_interrupt()) {
131 ret = crypto_blkcipher_encrypt(&fallback_desc, dst, src,
132 nbytes);
133 } else {
134 blkcipher_walk_init(&walk, dst, src, nbytes);
135 ret = blkcipher_walk_virt_block(desc, &walk, AES_BLOCK_SIZE);
136 while ((nbytes = walk.nbytes) >= AES_BLOCK_SIZE) {
137 preempt_disable();
138 pagefault_disable();
139 enable_kernel_altivec();
140 enable_kernel_vsx();
141 aes_p8_ctr32_encrypt_blocks(walk.src.virt.addr,
142 walk.dst.virt.addr,
143 (nbytes &
144 AES_BLOCK_MASK) /
145 AES_BLOCK_SIZE,
146 &ctx->enc_key,
147 walk.iv);
148 pagefault_enable();
149 preempt_enable();
150
151 /* We need to update IV mostly for last bytes/round */
152 inc = (nbytes & AES_BLOCK_MASK) / AES_BLOCK_SIZE;
153 if (inc > 0)
154 while (inc--)
155 crypto_inc(walk.iv, AES_BLOCK_SIZE);
156
157 nbytes &= AES_BLOCK_SIZE - 1;
158 ret = blkcipher_walk_done(desc, &walk, nbytes);
159 }
160 if (walk.nbytes) {
161 p8_aes_ctr_final(ctx, &walk);
162 ret = blkcipher_walk_done(desc, &walk, 0);
163 }
164 }
165
166 return ret;
167 }
168
169 struct crypto_alg p8_aes_ctr_alg = {
170 .cra_name = "ctr(aes)",
171 .cra_driver_name = "p8_aes_ctr",
172 .cra_module = THIS_MODULE,
173 .cra_priority = 2000,
174 .cra_type = &crypto_blkcipher_type,
175 .cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER | CRYPTO_ALG_NEED_FALLBACK,
176 .cra_alignmask = 0,
177 .cra_blocksize = 1,
178 .cra_ctxsize = sizeof(struct p8_aes_ctr_ctx),
179 .cra_init = p8_aes_ctr_init,
180 .cra_exit = p8_aes_ctr_exit,
181 .cra_blkcipher = {
182 .ivsize = AES_BLOCK_SIZE,
183 .min_keysize = AES_MIN_KEY_SIZE,
184 .max_keysize = AES_MAX_KEY_SIZE,
185 .setkey = p8_aes_ctr_setkey,
186 .encrypt = p8_aes_ctr_crypt,
187 .decrypt = p8_aes_ctr_crypt,
188 },
189 };
190