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