xref: /openbmc/linux/drivers/crypto/vmx/aes_cbc.c (revision d7a3d85e)
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 
33 struct p8_aes_cbc_ctx {
34     struct crypto_blkcipher *fallback;
35     struct aes_key enc_key;
36     struct aes_key dec_key;
37 };
38 
39 static 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 = crypto_alloc_blkcipher(alg, 0 ,CRYPTO_ALG_NEED_FALLBACK);
51     if (IS_ERR(fallback)) {
52         printk(KERN_ERR "Failed to allocate transformation for '%s': %ld\n",
53                 alg, PTR_ERR(fallback));
54         return PTR_ERR(fallback);
55     }
56     printk(KERN_INFO "Using '%s' as fallback implementation.\n",
57             crypto_tfm_alg_driver_name((struct crypto_tfm *) fallback));
58 
59     crypto_blkcipher_set_flags(fallback,
60             crypto_blkcipher_get_flags((struct crypto_blkcipher *) tfm));
61     ctx->fallback = fallback;
62 
63     return 0;
64 }
65 
66 static void p8_aes_cbc_exit(struct crypto_tfm *tfm)
67 {
68     struct p8_aes_cbc_ctx *ctx = crypto_tfm_ctx(tfm);
69 
70     if (ctx->fallback) {
71         crypto_free_blkcipher(ctx->fallback);
72         ctx->fallback = NULL;
73     }
74 }
75 
76 static int p8_aes_cbc_setkey(struct crypto_tfm *tfm, const u8 *key,
77     unsigned int keylen)
78 {
79     int ret;
80     struct p8_aes_cbc_ctx *ctx = crypto_tfm_ctx(tfm);
81 
82     pagefault_disable();
83     enable_kernel_altivec();
84     ret = aes_p8_set_encrypt_key(key, keylen * 8, &ctx->enc_key);
85     ret += aes_p8_set_decrypt_key(key, keylen * 8, &ctx->dec_key);
86     pagefault_enable();
87 
88     ret += crypto_blkcipher_setkey(ctx->fallback, key, keylen);
89     return ret;
90 }
91 
92 static int p8_aes_cbc_encrypt(struct blkcipher_desc *desc,
93     struct scatterlist *dst, struct scatterlist *src,
94     unsigned int nbytes)
95 {
96     int ret;
97     struct blkcipher_walk walk;
98     struct p8_aes_cbc_ctx *ctx = crypto_tfm_ctx(
99             crypto_blkcipher_tfm(desc->tfm));
100     struct blkcipher_desc fallback_desc = {
101         .tfm = ctx->fallback,
102         .info = desc->info,
103         .flags = desc->flags
104     };
105 
106     if (in_interrupt()) {
107         ret = crypto_blkcipher_encrypt(&fallback_desc, dst, src, nbytes);
108     } else {
109         pagefault_disable();
110         enable_kernel_altivec();
111 
112 	blkcipher_walk_init(&walk, dst, src, nbytes);
113         ret = blkcipher_walk_virt(desc, &walk);
114         while ((nbytes = walk.nbytes)) {
115 			aes_p8_cbc_encrypt(walk.src.virt.addr, walk.dst.virt.addr,
116 				nbytes & AES_BLOCK_MASK, &ctx->enc_key, walk.iv, 1);
117 			nbytes &= AES_BLOCK_SIZE - 1;
118 			ret = blkcipher_walk_done(desc, &walk, nbytes);
119 	}
120 
121         pagefault_enable();
122     }
123 
124     return ret;
125 }
126 
127 static int p8_aes_cbc_decrypt(struct blkcipher_desc *desc,
128     struct scatterlist *dst, struct scatterlist *src,
129     unsigned int nbytes)
130 {
131     int ret;
132     struct blkcipher_walk walk;
133     struct p8_aes_cbc_ctx *ctx = crypto_tfm_ctx(
134             crypto_blkcipher_tfm(desc->tfm));
135     struct blkcipher_desc fallback_desc = {
136         .tfm = ctx->fallback,
137         .info = desc->info,
138         .flags = desc->flags
139     };
140 
141     if (in_interrupt()) {
142         ret = crypto_blkcipher_decrypt(&fallback_desc, dst, src, nbytes);
143     } else {
144         pagefault_disable();
145         enable_kernel_altivec();
146 
147 	blkcipher_walk_init(&walk, dst, src, nbytes);
148         ret = blkcipher_walk_virt(desc, &walk);
149         while ((nbytes = walk.nbytes)) {
150 			aes_p8_cbc_encrypt(walk.src.virt.addr, walk.dst.virt.addr,
151 				nbytes & AES_BLOCK_MASK, &ctx->dec_key, walk.iv, 0);
152 			nbytes &= AES_BLOCK_SIZE - 1;
153 			ret = blkcipher_walk_done(desc, &walk, nbytes);
154 		}
155 
156         pagefault_enable();
157     }
158 
159     return ret;
160 }
161 
162 
163 struct crypto_alg p8_aes_cbc_alg = {
164     .cra_name = "cbc(aes)",
165     .cra_driver_name = "p8_aes_cbc",
166     .cra_module = THIS_MODULE,
167     .cra_priority = 1000,
168     .cra_type = &crypto_blkcipher_type,
169     .cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER | CRYPTO_ALG_NEED_FALLBACK,
170     .cra_alignmask = 0,
171     .cra_blocksize = AES_BLOCK_SIZE,
172     .cra_ctxsize = sizeof(struct p8_aes_cbc_ctx),
173     .cra_init = p8_aes_cbc_init,
174     .cra_exit = p8_aes_cbc_exit,
175     .cra_blkcipher = {
176         .ivsize = 0,
177         .min_keysize = AES_MIN_KEY_SIZE,
178         .max_keysize = AES_MAX_KEY_SIZE,
179         .setkey = p8_aes_cbc_setkey,
180         .encrypt = p8_aes_cbc_encrypt,
181         .decrypt = p8_aes_cbc_decrypt,
182     },
183 };
184 
185