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
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
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
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
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
136 static int p8_aes_xts_encrypt(struct skcipher_request *req)
137 {
138 return p8_aes_xts_crypt(req, 1);
139 }
140
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
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