xref: /openbmc/linux/drivers/crypto/vmx/aes_cbc.c (revision 0edbfea5)
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 =
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 
69 static 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 
79 static 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_vsx();
88 	ret = aes_p8_set_encrypt_key(key, keylen * 8, &ctx->enc_key);
89 	ret += aes_p8_set_decrypt_key(key, keylen * 8, &ctx->dec_key);
90 	disable_kernel_vsx();
91 	pagefault_enable();
92 	preempt_enable();
93 
94 	ret += crypto_blkcipher_setkey(ctx->fallback, key, keylen);
95 	return ret;
96 }
97 
98 static 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_vsx();
119 
120 		blkcipher_walk_init(&walk, dst, src, nbytes);
121 		ret = blkcipher_walk_virt(desc, &walk);
122 		while ((nbytes = walk.nbytes)) {
123 			aes_p8_cbc_encrypt(walk.src.virt.addr,
124 					   walk.dst.virt.addr,
125 					   nbytes & AES_BLOCK_MASK,
126 					   &ctx->enc_key, walk.iv, 1);
127 			nbytes &= AES_BLOCK_SIZE - 1;
128 			ret = blkcipher_walk_done(desc, &walk, nbytes);
129 		}
130 
131 		disable_kernel_vsx();
132 		pagefault_enable();
133 		preempt_enable();
134 	}
135 
136 	return ret;
137 }
138 
139 static 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_vsx();
160 
161 		blkcipher_walk_init(&walk, dst, src, nbytes);
162 		ret = blkcipher_walk_virt(desc, &walk);
163 		while ((nbytes = walk.nbytes)) {
164 			aes_p8_cbc_encrypt(walk.src.virt.addr,
165 					   walk.dst.virt.addr,
166 					   nbytes & AES_BLOCK_MASK,
167 					   &ctx->dec_key, walk.iv, 0);
168 			nbytes &= AES_BLOCK_SIZE - 1;
169 			ret = blkcipher_walk_done(desc, &walk, nbytes);
170 		}
171 
172 		disable_kernel_vsx();
173 		pagefault_enable();
174 		preempt_enable();
175 	}
176 
177 	return ret;
178 }
179 
180 
181 struct 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 = AES_BLOCK_SIZE,
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