1 /*
2 * ARM NEON and scalar accelerated ChaCha and XChaCha stream ciphers,
3 * including ChaCha20 (RFC7539)
4 *
5 * Copyright (C) 2016 - 2017 Linaro, Ltd. <ard.biesheuvel@linaro.org>
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
10 *
11 * Based on:
12 * ChaCha20 256-bit cipher algorithm, RFC7539, SIMD glue code
13 *
14 * Copyright (C) 2015 Martin Willi
15 *
16 * This program is free software; you can redistribute it and/or modify
17 * it under the terms of the GNU General Public License as published by
18 * the Free Software Foundation; either version 2 of the License, or
19 * (at your option) any later version.
20 */
21
22 #include <crypto/algapi.h>
23 #include <crypto/internal/chacha.h>
24 #include <crypto/internal/simd.h>
25 #include <crypto/internal/skcipher.h>
26 #include <linux/jump_label.h>
27 #include <linux/kernel.h>
28 #include <linux/module.h>
29
30 #include <asm/hwcap.h>
31 #include <asm/neon.h>
32 #include <asm/simd.h>
33
34 asmlinkage void chacha_block_xor_neon(u32 *state, u8 *dst, const u8 *src,
35 int nrounds);
36 asmlinkage void chacha_4block_xor_neon(u32 *state, u8 *dst, const u8 *src,
37 int nrounds, int bytes);
38 asmlinkage void hchacha_block_neon(const u32 *state, u32 *out, int nrounds);
39
40 static __ro_after_init DEFINE_STATIC_KEY_FALSE(have_neon);
41
chacha_doneon(u32 * state,u8 * dst,const u8 * src,int bytes,int nrounds)42 static void chacha_doneon(u32 *state, u8 *dst, const u8 *src,
43 int bytes, int nrounds)
44 {
45 while (bytes > 0) {
46 int l = min(bytes, CHACHA_BLOCK_SIZE * 5);
47
48 if (l <= CHACHA_BLOCK_SIZE) {
49 u8 buf[CHACHA_BLOCK_SIZE];
50
51 memcpy(buf, src, l);
52 chacha_block_xor_neon(state, buf, buf, nrounds);
53 memcpy(dst, buf, l);
54 state[12] += 1;
55 break;
56 }
57 chacha_4block_xor_neon(state, dst, src, nrounds, l);
58 bytes -= l;
59 src += l;
60 dst += l;
61 state[12] += DIV_ROUND_UP(l, CHACHA_BLOCK_SIZE);
62 }
63 }
64
hchacha_block_arch(const u32 * state,u32 * stream,int nrounds)65 void hchacha_block_arch(const u32 *state, u32 *stream, int nrounds)
66 {
67 if (!static_branch_likely(&have_neon) || !crypto_simd_usable()) {
68 hchacha_block_generic(state, stream, nrounds);
69 } else {
70 kernel_neon_begin();
71 hchacha_block_neon(state, stream, nrounds);
72 kernel_neon_end();
73 }
74 }
75 EXPORT_SYMBOL(hchacha_block_arch);
76
chacha_init_arch(u32 * state,const u32 * key,const u8 * iv)77 void chacha_init_arch(u32 *state, const u32 *key, const u8 *iv)
78 {
79 chacha_init_generic(state, key, iv);
80 }
81 EXPORT_SYMBOL(chacha_init_arch);
82
chacha_crypt_arch(u32 * state,u8 * dst,const u8 * src,unsigned int bytes,int nrounds)83 void chacha_crypt_arch(u32 *state, u8 *dst, const u8 *src, unsigned int bytes,
84 int nrounds)
85 {
86 if (!static_branch_likely(&have_neon) || bytes <= CHACHA_BLOCK_SIZE ||
87 !crypto_simd_usable())
88 return chacha_crypt_generic(state, dst, src, bytes, nrounds);
89
90 do {
91 unsigned int todo = min_t(unsigned int, bytes, SZ_4K);
92
93 kernel_neon_begin();
94 chacha_doneon(state, dst, src, todo, nrounds);
95 kernel_neon_end();
96
97 bytes -= todo;
98 src += todo;
99 dst += todo;
100 } while (bytes);
101 }
102 EXPORT_SYMBOL(chacha_crypt_arch);
103
chacha_neon_stream_xor(struct skcipher_request * req,const struct chacha_ctx * ctx,const u8 * iv)104 static int chacha_neon_stream_xor(struct skcipher_request *req,
105 const struct chacha_ctx *ctx, const u8 *iv)
106 {
107 struct skcipher_walk walk;
108 u32 state[16];
109 int err;
110
111 err = skcipher_walk_virt(&walk, req, false);
112
113 chacha_init_generic(state, ctx->key, iv);
114
115 while (walk.nbytes > 0) {
116 unsigned int nbytes = walk.nbytes;
117
118 if (nbytes < walk.total)
119 nbytes = rounddown(nbytes, walk.stride);
120
121 if (!static_branch_likely(&have_neon) ||
122 !crypto_simd_usable()) {
123 chacha_crypt_generic(state, walk.dst.virt.addr,
124 walk.src.virt.addr, nbytes,
125 ctx->nrounds);
126 } else {
127 kernel_neon_begin();
128 chacha_doneon(state, walk.dst.virt.addr,
129 walk.src.virt.addr, nbytes, ctx->nrounds);
130 kernel_neon_end();
131 }
132 err = skcipher_walk_done(&walk, walk.nbytes - nbytes);
133 }
134
135 return err;
136 }
137
chacha_neon(struct skcipher_request * req)138 static int chacha_neon(struct skcipher_request *req)
139 {
140 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
141 struct chacha_ctx *ctx = crypto_skcipher_ctx(tfm);
142
143 return chacha_neon_stream_xor(req, ctx, req->iv);
144 }
145
xchacha_neon(struct skcipher_request * req)146 static int xchacha_neon(struct skcipher_request *req)
147 {
148 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
149 struct chacha_ctx *ctx = crypto_skcipher_ctx(tfm);
150 struct chacha_ctx subctx;
151 u32 state[16];
152 u8 real_iv[16];
153
154 chacha_init_generic(state, ctx->key, req->iv);
155 hchacha_block_arch(state, subctx.key, ctx->nrounds);
156 subctx.nrounds = ctx->nrounds;
157
158 memcpy(&real_iv[0], req->iv + 24, 8);
159 memcpy(&real_iv[8], req->iv + 16, 8);
160 return chacha_neon_stream_xor(req, &subctx, real_iv);
161 }
162
163 static struct skcipher_alg algs[] = {
164 {
165 .base.cra_name = "chacha20",
166 .base.cra_driver_name = "chacha20-neon",
167 .base.cra_priority = 300,
168 .base.cra_blocksize = 1,
169 .base.cra_ctxsize = sizeof(struct chacha_ctx),
170 .base.cra_module = THIS_MODULE,
171
172 .min_keysize = CHACHA_KEY_SIZE,
173 .max_keysize = CHACHA_KEY_SIZE,
174 .ivsize = CHACHA_IV_SIZE,
175 .chunksize = CHACHA_BLOCK_SIZE,
176 .walksize = 5 * CHACHA_BLOCK_SIZE,
177 .setkey = chacha20_setkey,
178 .encrypt = chacha_neon,
179 .decrypt = chacha_neon,
180 }, {
181 .base.cra_name = "xchacha20",
182 .base.cra_driver_name = "xchacha20-neon",
183 .base.cra_priority = 300,
184 .base.cra_blocksize = 1,
185 .base.cra_ctxsize = sizeof(struct chacha_ctx),
186 .base.cra_module = THIS_MODULE,
187
188 .min_keysize = CHACHA_KEY_SIZE,
189 .max_keysize = CHACHA_KEY_SIZE,
190 .ivsize = XCHACHA_IV_SIZE,
191 .chunksize = CHACHA_BLOCK_SIZE,
192 .walksize = 5 * CHACHA_BLOCK_SIZE,
193 .setkey = chacha20_setkey,
194 .encrypt = xchacha_neon,
195 .decrypt = xchacha_neon,
196 }, {
197 .base.cra_name = "xchacha12",
198 .base.cra_driver_name = "xchacha12-neon",
199 .base.cra_priority = 300,
200 .base.cra_blocksize = 1,
201 .base.cra_ctxsize = sizeof(struct chacha_ctx),
202 .base.cra_module = THIS_MODULE,
203
204 .min_keysize = CHACHA_KEY_SIZE,
205 .max_keysize = CHACHA_KEY_SIZE,
206 .ivsize = XCHACHA_IV_SIZE,
207 .chunksize = CHACHA_BLOCK_SIZE,
208 .walksize = 5 * CHACHA_BLOCK_SIZE,
209 .setkey = chacha12_setkey,
210 .encrypt = xchacha_neon,
211 .decrypt = xchacha_neon,
212 }
213 };
214
chacha_simd_mod_init(void)215 static int __init chacha_simd_mod_init(void)
216 {
217 if (!cpu_have_named_feature(ASIMD))
218 return 0;
219
220 static_branch_enable(&have_neon);
221
222 return IS_REACHABLE(CONFIG_CRYPTO_SKCIPHER) ?
223 crypto_register_skciphers(algs, ARRAY_SIZE(algs)) : 0;
224 }
225
chacha_simd_mod_fini(void)226 static void __exit chacha_simd_mod_fini(void)
227 {
228 if (IS_REACHABLE(CONFIG_CRYPTO_SKCIPHER) && cpu_have_named_feature(ASIMD))
229 crypto_unregister_skciphers(algs, ARRAY_SIZE(algs));
230 }
231
232 module_init(chacha_simd_mod_init);
233 module_exit(chacha_simd_mod_fini);
234
235 MODULE_DESCRIPTION("ChaCha and XChaCha stream ciphers (NEON accelerated)");
236 MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");
237 MODULE_LICENSE("GPL v2");
238 MODULE_ALIAS_CRYPTO("chacha20");
239 MODULE_ALIAS_CRYPTO("chacha20-neon");
240 MODULE_ALIAS_CRYPTO("xchacha20");
241 MODULE_ALIAS_CRYPTO("xchacha20-neon");
242 MODULE_ALIAS_CRYPTO("xchacha12");
243 MODULE_ALIAS_CRYPTO("xchacha12-neon");
244