xref: /openbmc/linux/drivers/crypto/vmx/aes_xts.c (revision dbb153c0)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * AES XTS routines supporting VMX In-core instructions on Power 8
4  *
5  * Copyright (C) 2015 International Business Machines Inc.
6  *
7  * Author: Leonidas S. Barbosa <leosilva@linux.vnet.ibm.com>
8  */
9 
10 #include <asm/simd.h>
11 #include <asm/switch_to.h>
12 #include <crypto/aes.h>
13 #include <crypto/internal/simd.h>
14 #include <crypto/internal/skcipher.h>
15 #include <crypto/xts.h>
16 
17 #include "aesp8-ppc.h"
18 
19 struct p8_aes_xts_ctx {
20 	struct crypto_skcipher *fallback;
21 	struct aes_key enc_key;
22 	struct aes_key dec_key;
23 	struct aes_key tweak_key;
24 };
25 
p8_aes_xts_init(struct crypto_skcipher * tfm)26 static int p8_aes_xts_init(struct crypto_skcipher *tfm)
27 {
28 	struct p8_aes_xts_ctx *ctx = crypto_skcipher_ctx(tfm);
29 	struct crypto_skcipher *fallback;
30 
31 	fallback = crypto_alloc_skcipher("xts(aes)", 0,
32 					 CRYPTO_ALG_NEED_FALLBACK |
33 					 CRYPTO_ALG_ASYNC);
34 	if (IS_ERR(fallback)) {
35 		pr_err("Failed to allocate xts(aes) fallback: %ld\n",
36 		       PTR_ERR(fallback));
37 		return PTR_ERR(fallback);
38 	}
39 
40 	crypto_skcipher_set_reqsize(tfm, sizeof(struct skcipher_request) +
41 				    crypto_skcipher_reqsize(fallback));
42 	ctx->fallback = fallback;
43 	return 0;
44 }
45 
p8_aes_xts_exit(struct crypto_skcipher * tfm)46 static void p8_aes_xts_exit(struct crypto_skcipher *tfm)
47 {
48 	struct p8_aes_xts_ctx *ctx = crypto_skcipher_ctx(tfm);
49 
50 	crypto_free_skcipher(ctx->fallback);
51 }
52 
p8_aes_xts_setkey(struct crypto_skcipher * tfm,const u8 * key,unsigned int keylen)53 static int p8_aes_xts_setkey(struct crypto_skcipher *tfm, const u8 *key,
54 			     unsigned int keylen)
55 {
56 	struct p8_aes_xts_ctx *ctx = crypto_skcipher_ctx(tfm);
57 	int ret;
58 
59 	ret = xts_verify_key(tfm, key, keylen);
60 	if (ret)
61 		return ret;
62 
63 	preempt_disable();
64 	pagefault_disable();
65 	enable_kernel_vsx();
66 	ret = aes_p8_set_encrypt_key(key + keylen/2, (keylen/2) * 8, &ctx->tweak_key);
67 	ret |= aes_p8_set_encrypt_key(key, (keylen/2) * 8, &ctx->enc_key);
68 	ret |= aes_p8_set_decrypt_key(key, (keylen/2) * 8, &ctx->dec_key);
69 	disable_kernel_vsx();
70 	pagefault_enable();
71 	preempt_enable();
72 
73 	ret |= crypto_skcipher_setkey(ctx->fallback, key, keylen);
74 
75 	return ret ? -EINVAL : 0;
76 }
77 
p8_aes_xts_crypt(struct skcipher_request * req,int enc)78 static int p8_aes_xts_crypt(struct skcipher_request *req, int enc)
79 {
80 	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
81 	const struct p8_aes_xts_ctx *ctx = crypto_skcipher_ctx(tfm);
82 	struct skcipher_walk walk;
83 	unsigned int nbytes;
84 	u8 tweak[AES_BLOCK_SIZE];
85 	int ret;
86 
87 	if (req->cryptlen < AES_BLOCK_SIZE)
88 		return -EINVAL;
89 
90 	if (!crypto_simd_usable() || (req->cryptlen % XTS_BLOCK_SIZE) != 0) {
91 		struct skcipher_request *subreq = skcipher_request_ctx(req);
92 
93 		*subreq = *req;
94 		skcipher_request_set_tfm(subreq, ctx->fallback);
95 		return enc ? crypto_skcipher_encrypt(subreq) :
96 			     crypto_skcipher_decrypt(subreq);
97 	}
98 
99 	ret = skcipher_walk_virt(&walk, req, false);
100 	if (ret)
101 		return ret;
102 
103 	preempt_disable();
104 	pagefault_disable();
105 	enable_kernel_vsx();
106 
107 	aes_p8_encrypt(walk.iv, tweak, &ctx->tweak_key);
108 
109 	disable_kernel_vsx();
110 	pagefault_enable();
111 	preempt_enable();
112 
113 	while ((nbytes = walk.nbytes) != 0) {
114 		preempt_disable();
115 		pagefault_disable();
116 		enable_kernel_vsx();
117 		if (enc)
118 			aes_p8_xts_encrypt(walk.src.virt.addr,
119 					   walk.dst.virt.addr,
120 					   round_down(nbytes, AES_BLOCK_SIZE),
121 					   &ctx->enc_key, NULL, tweak);
122 		else
123 			aes_p8_xts_decrypt(walk.src.virt.addr,
124 					   walk.dst.virt.addr,
125 					   round_down(nbytes, AES_BLOCK_SIZE),
126 					   &ctx->dec_key, NULL, tweak);
127 		disable_kernel_vsx();
128 		pagefault_enable();
129 		preempt_enable();
130 
131 		ret = skcipher_walk_done(&walk, nbytes % AES_BLOCK_SIZE);
132 	}
133 	return ret;
134 }
135 
p8_aes_xts_encrypt(struct skcipher_request * req)136 static int p8_aes_xts_encrypt(struct skcipher_request *req)
137 {
138 	return p8_aes_xts_crypt(req, 1);
139 }
140 
p8_aes_xts_decrypt(struct skcipher_request * req)141 static int p8_aes_xts_decrypt(struct skcipher_request *req)
142 {
143 	return p8_aes_xts_crypt(req, 0);
144 }
145 
146 struct skcipher_alg p8_aes_xts_alg = {
147 	.base.cra_name = "xts(aes)",
148 	.base.cra_driver_name = "p8_aes_xts",
149 	.base.cra_module = THIS_MODULE,
150 	.base.cra_priority = 2000,
151 	.base.cra_flags = CRYPTO_ALG_NEED_FALLBACK,
152 	.base.cra_blocksize = AES_BLOCK_SIZE,
153 	.base.cra_ctxsize = sizeof(struct p8_aes_xts_ctx),
154 	.setkey = p8_aes_xts_setkey,
155 	.encrypt = p8_aes_xts_encrypt,
156 	.decrypt = p8_aes_xts_decrypt,
157 	.init = p8_aes_xts_init,
158 	.exit = p8_aes_xts_exit,
159 	.min_keysize = 2 * AES_MIN_KEY_SIZE,
160 	.max_keysize = 2 * AES_MAX_KEY_SIZE,
161 	.ivsize = AES_BLOCK_SIZE,
162 };
163