crypto: vmx - Use skcipher for xts fallback
[sfrench/cifs-2.6.git] / drivers / crypto / vmx / aes_xts.c
1 /**
2  * AES XTS routines supporting VMX In-core instructions on 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 Foundations; 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 of FITNESS FOR A PARTICUPAR 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: Leonidas S. Barbosa <leosilva@linux.vnet.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 <crypto/xts.h>
31 #include <crypto/skcipher.h>
32
33 #include "aesp8-ppc.h"
34
35 struct p8_aes_xts_ctx {
36         struct crypto_skcipher *fallback;
37         struct aes_key enc_key;
38         struct aes_key dec_key;
39         struct aes_key tweak_key;
40 };
41
42 static int p8_aes_xts_init(struct crypto_tfm *tfm)
43 {
44         const char *alg;
45         struct crypto_skcipher *fallback;
46         struct p8_aes_xts_ctx *ctx = crypto_tfm_ctx(tfm);
47
48         if (!(alg = crypto_tfm_alg_name(tfm))) {
49                 printk(KERN_ERR "Failed to get algorithm name.\n");
50                 return -ENOENT;
51         }
52
53         fallback = crypto_alloc_skcipher(alg, 0,
54                         CRYPTO_ALG_ASYNC | CRYPTO_ALG_NEED_FALLBACK);
55         if (IS_ERR(fallback)) {
56                 printk(KERN_ERR
57                         "Failed to allocate transformation for '%s': %ld\n",
58                         alg, PTR_ERR(fallback));
59                 return PTR_ERR(fallback);
60         }
61         printk(KERN_INFO "Using '%s' as fallback implementation.\n",
62                 crypto_skcipher_driver_name(fallback));
63
64         crypto_skcipher_set_flags(
65                 fallback,
66                 crypto_skcipher_get_flags((struct crypto_skcipher *)tfm));
67         ctx->fallback = fallback;
68
69         return 0;
70 }
71
72 static void p8_aes_xts_exit(struct crypto_tfm *tfm)
73 {
74         struct p8_aes_xts_ctx *ctx = crypto_tfm_ctx(tfm);
75
76         if (ctx->fallback) {
77                 crypto_free_skcipher(ctx->fallback);
78                 ctx->fallback = NULL;
79         }
80 }
81
82 static int p8_aes_xts_setkey(struct crypto_tfm *tfm, const u8 *key,
83                              unsigned int keylen)
84 {
85         int ret;
86         struct p8_aes_xts_ctx *ctx = crypto_tfm_ctx(tfm);
87
88         ret = xts_check_key(tfm, key, keylen);
89         if (ret)
90                 return ret;
91
92         preempt_disable();
93         pagefault_disable();
94         enable_kernel_vsx();
95         ret = aes_p8_set_encrypt_key(key + keylen/2, (keylen/2) * 8, &ctx->tweak_key);
96         ret += aes_p8_set_encrypt_key(key, (keylen/2) * 8, &ctx->enc_key);
97         ret += aes_p8_set_decrypt_key(key, (keylen/2) * 8, &ctx->dec_key);
98         disable_kernel_vsx();
99         pagefault_enable();
100         preempt_enable();
101
102         ret += crypto_skcipher_setkey(ctx->fallback, key, keylen);
103         return ret;
104 }
105
106 static int p8_aes_xts_crypt(struct blkcipher_desc *desc,
107                             struct scatterlist *dst,
108                             struct scatterlist *src,
109                             unsigned int nbytes, int enc)
110 {
111         int ret;
112         u8 tweak[AES_BLOCK_SIZE];
113         u8 *iv;
114         struct blkcipher_walk walk;
115         struct p8_aes_xts_ctx *ctx =
116                 crypto_tfm_ctx(crypto_blkcipher_tfm(desc->tfm));
117
118         if (in_interrupt()) {
119                 SKCIPHER_REQUEST_ON_STACK(req, ctx->fallback);
120                 skcipher_request_set_tfm(req, ctx->fallback);
121                 skcipher_request_set_callback(req, desc->flags, NULL, NULL);
122                 skcipher_request_set_crypt(req, src, dst, nbytes, desc->info);
123                 ret = enc? crypto_skcipher_encrypt(req) : crypto_skcipher_decrypt(req);
124                 skcipher_request_zero(req);
125         } else {
126                 preempt_disable();
127                 pagefault_disable();
128                 enable_kernel_vsx();
129
130                 blkcipher_walk_init(&walk, dst, src, nbytes);
131
132                 ret = blkcipher_walk_virt(desc, &walk);
133                 iv = walk.iv;
134                 memset(tweak, 0, AES_BLOCK_SIZE);
135                 aes_p8_encrypt(iv, tweak, &ctx->tweak_key);
136
137                 while ((nbytes = walk.nbytes)) {
138                         if (enc)
139                                 aes_p8_xts_encrypt(walk.src.virt.addr, walk.dst.virt.addr,
140                                                 nbytes & AES_BLOCK_MASK, &ctx->enc_key, NULL, tweak);
141                         else
142                                 aes_p8_xts_decrypt(walk.src.virt.addr, walk.dst.virt.addr,
143                                                 nbytes & AES_BLOCK_MASK, &ctx->dec_key, NULL, tweak);
144
145                         nbytes &= AES_BLOCK_SIZE - 1;
146                         ret = blkcipher_walk_done(desc, &walk, nbytes);
147                 }
148
149                 disable_kernel_vsx();
150                 pagefault_enable();
151                 preempt_enable();
152         }
153         return ret;
154 }
155
156 static int p8_aes_xts_encrypt(struct blkcipher_desc *desc,
157                               struct scatterlist *dst,
158                               struct scatterlist *src, unsigned int nbytes)
159 {
160         return p8_aes_xts_crypt(desc, dst, src, nbytes, 1);
161 }
162
163 static int p8_aes_xts_decrypt(struct blkcipher_desc *desc,
164                               struct scatterlist *dst,
165                               struct scatterlist *src, unsigned int nbytes)
166 {
167         return p8_aes_xts_crypt(desc, dst, src, nbytes, 0);
168 }
169
170 struct crypto_alg p8_aes_xts_alg = {
171         .cra_name = "xts(aes)",
172         .cra_driver_name = "p8_aes_xts",
173         .cra_module = THIS_MODULE,
174         .cra_priority = 2000,
175         .cra_type = &crypto_blkcipher_type,
176         .cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER | CRYPTO_ALG_NEED_FALLBACK,
177         .cra_alignmask = 0,
178         .cra_blocksize = AES_BLOCK_SIZE,
179         .cra_ctxsize = sizeof(struct p8_aes_xts_ctx),
180         .cra_init = p8_aes_xts_init,
181         .cra_exit = p8_aes_xts_exit,
182         .cra_blkcipher = {
183                         .ivsize = AES_BLOCK_SIZE,
184                         .min_keysize = 2 * AES_MIN_KEY_SIZE,
185                         .max_keysize = 2 * AES_MAX_KEY_SIZE,
186                         .setkey  = p8_aes_xts_setkey,
187                         .encrypt = p8_aes_xts_encrypt,
188                         .decrypt = p8_aes_xts_decrypt,
189         }
190 };