summaryrefslogtreecommitdiffstats
path: root/lib/crypto/chacha20poly1305.c
blob: 6d83cafebc69ce06b3b37b96f665f3537a0748b5 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
// SPDX-License-Identifier: GPL-2.0 OR MIT
/*
 * Copyright (C) 2015-2019 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
 *
 * This is an implementation of the ChaCha20Poly1305 AEAD construction.
 *
 * Information: https://tools.ietf.org/html/rfc8439
 */

#include <crypto/algapi.h>
#include <crypto/chacha20poly1305.h>
#include <crypto/chacha.h>
#include <crypto/poly1305.h>
#include <crypto/scatterwalk.h>

#include <asm/unaligned.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/mm.h>
#include <linux/module.h>

#define CHACHA_KEY_WORDS	(CHACHA_KEY_SIZE / sizeof(u32))

bool __init chacha20poly1305_selftest(void);

static void chacha_load_key(u32 *k, const u8 *in)
{
	k[0] = get_unaligned_le32(in);
	k[1] = get_unaligned_le32(in + 4);
	k[2] = get_unaligned_le32(in + 8);
	k[3] = get_unaligned_le32(in + 12);
	k[4] = get_unaligned_le32(in + 16);
	k[5] = get_unaligned_le32(in + 20);
	k[6] = get_unaligned_le32(in + 24);
	k[7] = get_unaligned_le32(in + 28);
}

static void xchacha_init(u32 *chacha_state, const u8 *key, const u8 *nonce)
{
	u32 k[CHACHA_KEY_WORDS];
	u8 iv[CHACHA_IV_SIZE];

	memset(iv, 0, 8);
	memcpy(iv + 8, nonce + 16, 8);

	chacha_load_key(k, key);

	/* Compute the subkey given the original key and first 128 nonce bits */
	chacha_init(chacha_state, k, nonce);
	hchacha_block(chacha_state, k, 20);

	chacha_init(chacha_state, k, iv);

	memzero_explicit(k, sizeof(k));
	memzero_explicit(iv, sizeof(iv));
}

static void
__chacha20poly1305_encrypt(u8 *dst, const u8 *src, const size_t src_len,
			   const u8 *ad, const size_t ad_len, u32 *chacha_state)
{
	const u8 *pad0 = page_address(ZERO_PAGE(0));
	struct poly1305_desc_ctx poly1305_state;
	union {
		u8 block0[POLY1305_KEY_SIZE];
		__le64 lens[2];
	} b;

	chacha20_crypt(chacha_state, b.block0, pad0, sizeof(b.block0));
	poly1305_init(&poly1305_state, b.block0);

	poly1305_update(&poly1305_state, ad, ad_len);
	if (ad_len & 0xf)
		poly1305_update(&poly1305_state, pad0, 0x10 - (ad_len & 0xf));

	chacha20_crypt(chacha_state, dst, src, src_len);

	poly1305_update(&poly1305_state, dst, src_len);
	if (src_len & 0xf)
		poly1305_update(&poly1305_state, pad0, 0x10 - (src_len & 0xf));

	b.lens[0] = cpu_to_le64(ad_len);
	b.lens[1] = cpu_to_le64(src_len);
	poly1305_update(&poly1305_state, (u8 *)b.lens, sizeof(b.lens));

	poly1305_final(&poly1305_state, dst + src_len);

	memzero_explicit(chacha_state, CHACHA_STATE_WORDS * sizeof(u32));
	memzero_explicit(&b, sizeof(b));
}

void chacha20poly1305_encrypt(u8 *dst, const u8 *src, const size_t src_len,
			      const u8 *ad, const size_t ad_len,
			      const u64 nonce,
			      const u8 key[CHACHA20POLY1305_KEY_SIZE])
{
	u32 chacha_state[CHACHA_STATE_WORDS];
	u32 k[CHACHA_KEY_WORDS];
	__le64 iv[2];

	chacha_load_key(k, key);

	iv[0] = 0;
	iv[1] = cpu_to_le64(nonce);

	chacha_init(chacha_state, k, (u8 *)iv);
	__chacha20poly1305_encrypt(dst, src, src_len, ad, ad_len, chacha_state);

	memzero_explicit(iv, sizeof(iv));
	memzero_explicit(k, sizeof(k));
}
EXPORT_SYMBOL(chacha20poly1305_encrypt);

void xchacha20poly1305_encrypt(u8 *dst, const u8 *src, const size_t src_len,
			       const u8 *ad, const size_t ad_len,
			       const u8 nonce[XCHACHA20POLY1305_NONCE_SIZE],
			       const u8 key[CHACHA20POLY1305_KEY_SIZE])
{
	u32 chacha_state[CHACHA_STATE_WORDS];

	xchacha_init(chacha_state, key, nonce);
	__chacha20poly1305_encrypt(dst, src, src_len, ad, ad_len, chacha_state);
}
EXPORT_SYMBOL(xchacha20poly1305_encrypt);

static bool
__chacha20poly1305_decrypt(u8 *dst, const u8 *src, const size_t src_len,
			   const u8 *ad, const size_t ad_len, u32 *chacha_state)
{
	const u8 *pad0 = page_address(ZERO_PAGE(0));
	struct poly1305_desc_ctx poly1305_state;
	size_t dst_len;
	int ret;
	union {
		u8 block0[POLY1305_KEY_SIZE];
		u8 mac[POLY1305_DIGEST_SIZE];
		__le64 lens[2];
	} b;

	if (unlikely(src_len < POLY1305_DIGEST_SIZE))
		return false;

	chacha20_crypt(chacha_state, b.block0, pad0, sizeof(b.block0));
	poly1305_init(&poly1305_state, b.block0);

	poly1305_update(&poly1305_state, ad, ad_len);
	if (ad_len & 0xf)
		poly1305_update(&poly1305_state, pad0, 0x10 - (ad_len & 0xf));

	dst_len = src_len - POLY1305_DIGEST_SIZE;
	poly1305_update(&poly1305_state, src, dst_len);
	if (dst_len & 0xf)
		poly1305_update(&poly1305_state, pad0, 0x10 - (dst_len & 0xf));

	b.lens[0] = cpu_to_le64(ad_len);
	b.lens[1] = cpu_to_le64(dst_len);
	poly1305_update(&poly1305_state, (u8 *)b.lens, sizeof(b.lens));

	poly1305_final(&poly1305_state, b.mac);

	ret = crypto_memneq(b.mac, src + dst_len, POLY1305_DIGEST_SIZE);
	if (likely(!ret))
		chacha20_crypt(chacha_state, dst, src, dst_len);

	memzero_explicit(&b, sizeof(b));

	return !ret;
}

bool chacha20poly1305_decrypt(u8 *dst, const u8 *src, const size_t src_len,
			      const u8 *ad, const size_t ad_len,
			      const u64 nonce,
			      const u8 key[CHACHA20POLY1305_KEY_SIZE])
{
	u32 chacha_state[CHACHA_STATE_WORDS];
	u32 k[CHACHA_KEY_WORDS];
	__le64 iv[2];
	bool ret;

	chacha_load_key(k, key);

	iv[0] = 0;
	iv[1] = cpu_to_le64(nonce);

	chacha_init(chacha_state, k, (u8 *)iv);
	ret = __chacha20poly1305_decrypt(dst, src, src_len, ad, ad_len,
					 chacha_state);

	memzero_explicit(chacha_state, sizeof(chacha_state));
	memzero_explicit(iv, sizeof(iv));
	memzero_explicit(k, sizeof(k));
	return ret;
}
EXPORT_SYMBOL(chacha20poly1305_decrypt);

bool xchacha20poly1305_decrypt(u8 *dst, const u8 *src, const size_t src_len,
			       const u8 *ad, const size_t ad_len,
			       const u8 nonce[XCHACHA20POLY1305_NONCE_SIZE],
			       const u8 key[CHACHA20POLY1305_KEY_SIZE])
{
	u32 chacha_state[CHACHA_STATE_WORDS];

	xchacha_init(chacha_state, key, nonce);
	return __chacha20poly1305_decrypt(dst, src, src_len, ad, ad_len,
					  chacha_state);
}
EXPORT_SYMBOL(xchacha20poly1305_decrypt);

static
bool chacha20poly1305_crypt_sg_inplace(struct scatterlist *src,
				       const size_t src_len,
				       const u8 *ad, const size_t ad_len,
				       const u64 nonce,
				       const u8 key[CHACHA20POLY1305_KEY_SIZE],
				       int encrypt)
{
	const u8 *pad0 = page_address(ZERO_PAGE(0));
	struct poly1305_desc_ctx poly1305_state;
	u32 chacha_state[CHACHA_STATE_WORDS];
	struct sg_mapping_iter miter;
	size_t partial = 0;
	unsigned int flags;
	bool ret = true;
	int sl;
	union {
		struct {
			u32 k[CHACHA_KEY_WORDS];
			__le64 iv[2];
		};
		u8 block0[POLY1305_KEY_SIZE];
		u8 chacha_stream[CHACHA_BLOCK_SIZE];
		struct {
			u8 mac[2][POLY1305_DIGEST_SIZE];
		};
		__le64 lens[2];
	} b __aligned(16);

	chacha_load_key(b.k, key);

	b.iv[0] = 0;
	b.iv[1] = cpu_to_le64(nonce);

	chacha_init(chacha_state, b.k, (u8 *)b.iv);
	chacha20_crypt(chacha_state, b.block0, pad0, sizeof(b.block0));
	poly1305_init(&poly1305_state, b.block0);

	if (unlikely(ad_len)) {
		poly1305_update(&poly1305_state, ad, ad_len);
		if (ad_len & 0xf)
			poly1305_update(&poly1305_state, pad0, 0x10 - (ad_len & 0xf));
	}

	flags = SG_MITER_TO_SG;
	if (!preemptible())
		flags |= SG_MITER_ATOMIC;

	sg_miter_start(&miter, src, sg_nents(src), flags);

	for (sl = src_len; sl > 0 && sg_miter_next(&miter); sl -= miter.length) {
		u8 *addr = miter.addr;
		size_t length = min_t(size_t, sl, miter.length);

		if (!encrypt)
			poly1305_update(&poly1305_state, addr, length);

		if (unlikely(partial)) {
			size_t l = min(length, CHACHA_BLOCK_SIZE - partial);

			crypto_xor(addr, b.chacha_stream + partial, l);
			partial = (partial + l) & (CHACHA_BLOCK_SIZE - 1);

			addr += l;
			length -= l;
		}

		if (likely(length >= CHACHA_BLOCK_SIZE || length == sl)) {
			size_t l = length;

			if (unlikely(length < sl))
				l &= ~(CHACHA_BLOCK_SIZE - 1);
			chacha20_crypt(chacha_state, addr, addr, l);
			addr += l;
			length -= l;
		}

		if (unlikely(length > 0)) {
			chacha20_crypt(chacha_state, b.chacha_stream, pad0,
				       CHACHA_BLOCK_SIZE);
			crypto_xor(addr, b.chacha_stream, length);
			partial = length;
		}

		if (encrypt)
			poly1305_update(&poly1305_state, miter.addr,
					min_t(size_t, sl, miter.length));
	}

	if (src_len & 0xf)
		poly1305_update(&poly1305_state, pad0, 0x10 - (src_len & 0xf));

	b.lens[0] = cpu_to_le64(ad_len);
	b.lens[1] = cpu_to_le64(src_len);
	poly1305_update(&poly1305_state, (u8 *)b.lens, sizeof(b.lens));

	if (likely(sl <= -POLY1305_DIGEST_SIZE)) {
		if (encrypt) {
			poly1305_final(&poly1305_state,
				       miter.addr + miter.length + sl);
			ret = true;
		} else {
			poly1305_final(&poly1305_state, b.mac[0]);
			ret = !crypto_memneq(b.mac[0],
					     miter.addr + miter.length + sl,
					     POLY1305_DIGEST_SIZE);
		}
	}

	sg_miter_stop(&miter);

	if (unlikely(sl > -POLY1305_DIGEST_SIZE)) {
		poly1305_final(&poly1305_state, b.mac[1]);
		scatterwalk_map_and_copy(b.mac[encrypt], src, src_len,
					 sizeof(b.mac[1]), encrypt);
		ret = encrypt ||
		      !crypto_memneq(b.mac[0], b.mac[1], POLY1305_DIGEST_SIZE);
	}

	memzero_explicit(chacha_state, sizeof(chacha_state));
	memzero_explicit(&b, sizeof(b));

	return ret;
}

bool chacha20poly1305_encrypt_sg_inplace(struct scatterlist *src, size_t src_len,
					 const u8 *ad, const size_t ad_len,
					 const u64 nonce,
					 const u8 key[CHACHA20POLY1305_KEY_SIZE])
{
	return chacha20poly1305_crypt_sg_inplace(src, src_len, ad, ad_len,
						 nonce, key, 1);
}
EXPORT_SYMBOL(chacha20poly1305_encrypt_sg_inplace);

bool chacha20poly1305_decrypt_sg_inplace(struct scatterlist *src, size_t src_len,
					 const u8 *ad, const size_t ad_len,
					 const u64 nonce,
					 const u8 key[CHACHA20POLY1305_KEY_SIZE])
{
	if (unlikely(src_len < POLY1305_DIGEST_SIZE))
		return false;

	return chacha20poly1305_crypt_sg_inplace(src,
						 src_len - POLY1305_DIGEST_SIZE,
						 ad, ad_len, nonce, key, 0);
}
EXPORT_SYMBOL(chacha20poly1305_decrypt_sg_inplace);

static int __init mod_init(void)
{
	if (!IS_ENABLED(CONFIG_CRYPTO_MANAGER_DISABLE_TESTS) &&
	    WARN_ON(!chacha20poly1305_selftest()))
		return -ENODEV;
	return 0;
}

module_init(mod_init);
MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("ChaCha20Poly1305 AEAD construction");
MODULE_AUTHOR("Jason A. Donenfeld <Jason@zx2c4.com>");