aboutsummaryrefslogtreecommitdiffstats
path: root/arch/arm64/crypto/ghash-ce-glue.c
blob: ee6aaac05905db308d15e0fb667a146f74a090da (plain) (blame)
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
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
/*
 * Accelerated GHASH implementation with ARMv8 PMULL instructions.
 *
 * Copyright (C) 2014 - 2017 Linaro Ltd. <ard.biesheuvel@linaro.org>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published
 * by the Free Software Foundation.
 */

#include <asm/neon.h>
#include <asm/simd.h>
#include <asm/unaligned.h>
#include <crypto/aes.h>
#include <crypto/algapi.h>
#include <crypto/b128ops.h>
#include <crypto/gf128mul.h>
#include <crypto/internal/aead.h>
#include <crypto/internal/hash.h>
#include <crypto/internal/skcipher.h>
#include <crypto/scatterwalk.h>
#include <linux/cpufeature.h>
#include <linux/crypto.h>
#include <linux/module.h>

MODULE_DESCRIPTION("GHASH and AES-GCM using ARMv8 Crypto Extensions");
MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");
MODULE_LICENSE("GPL v2");

#define GHASH_BLOCK_SIZE	16
#define GHASH_DIGEST_SIZE	16
#define GCM_IV_SIZE		12

struct ghash_key {
	u64 a;
	u64 b;
	be128 k;
};

struct ghash_desc_ctx {
	u64 digest[GHASH_DIGEST_SIZE/sizeof(u64)];
	u8 buf[GHASH_BLOCK_SIZE];
	u32 count;
};

struct gcm_aes_ctx {
	struct crypto_aes_ctx	aes_key;
	struct ghash_key	ghash_key;
};

asmlinkage void pmull_ghash_update(int blocks, u64 dg[], const char *src,
				   struct ghash_key const *k, const char *head);

asmlinkage void pmull_gcm_encrypt(int blocks, u64 dg[], u8 dst[],
				  const u8 src[], struct ghash_key const *k,
				  u8 ctr[], int rounds, u8 ks[]);

asmlinkage void pmull_gcm_decrypt(int blocks, u64 dg[], u8 dst[],
				  const u8 src[], struct ghash_key const *k,
				  u8 ctr[], int rounds);

asmlinkage void pmull_gcm_encrypt_block(u8 dst[], u8 const src[],
					u32 const rk[], int rounds);

asmlinkage void __aes_arm64_encrypt(u32 *rk, u8 *out, const u8 *in, int rounds);

static int ghash_init(struct shash_desc *desc)
{
	struct ghash_desc_ctx *ctx = shash_desc_ctx(desc);

	*ctx = (struct ghash_desc_ctx){};
	return 0;
}

static void ghash_do_update(int blocks, u64 dg[], const char *src,
			    struct ghash_key *key, const char *head)
{
	if (likely(may_use_simd())) {
		kernel_neon_begin();
		pmull_ghash_update(blocks, dg, src, key, head);
		kernel_neon_end();
	} else {
		be128 dst = { cpu_to_be64(dg[1]), cpu_to_be64(dg[0]) };

		do {
			const u8 *in = src;

			if (head) {
				in = head;
				blocks++;
				head = NULL;
			} else {
				src += GHASH_BLOCK_SIZE;
			}

			crypto_xor((u8 *)&dst, in, GHASH_BLOCK_SIZE);
			gf128mul_lle(&dst, &key->k);
		} while (--blocks);

		dg[0] = be64_to_cpu(dst.b);
		dg[1] = be64_to_cpu(dst.a);
	}
}

static int ghash_update(struct shash_desc *desc, const u8 *src,
			unsigned int len)
{
	struct ghash_desc_ctx *ctx = shash_desc_ctx(desc);
	unsigned int partial = ctx->count % GHASH_BLOCK_SIZE;

	ctx->count += len;

	if ((partial + len) >= GHASH_BLOCK_SIZE) {
		struct ghash_key *key = crypto_shash_ctx(desc->tfm);
		int blocks;

		if (partial) {
			int p = GHASH_BLOCK_SIZE - partial;

			memcpy(ctx->buf + partial, src, p);
			src += p;
			len -= p;
		}

		blocks = len / GHASH_BLOCK_SIZE;
		len %= GHASH_BLOCK_SIZE;

		ghash_do_update(blocks, ctx->digest, src, key,
				partial ? ctx->buf : NULL);

		src += blocks * GHASH_BLOCK_SIZE;
		partial = 0;
	}
	if (len)
		memcpy(ctx->buf + partial, src, len);
	return 0;
}

static int ghash_final(struct shash_desc *desc, u8 *dst)
{
	struct ghash_desc_ctx *ctx = shash_desc_ctx(desc);
	unsigned int partial = ctx->count % GHASH_BLOCK_SIZE;

	if (partial) {
		struct ghash_key *key = crypto_shash_ctx(desc->tfm);

		memset(ctx->buf + partial, 0, GHASH_BLOCK_SIZE - partial);

		ghash_do_update(1, ctx->digest, ctx->buf, key, NULL);
	}
	put_unaligned_be64(ctx->digest[1], dst);
	put_unaligned_be64(ctx->digest[0], dst + 8);

	*ctx = (struct ghash_desc_ctx){};
	return 0;
}

static int __ghash_setkey(struct ghash_key *key,
			  const u8 *inkey, unsigned int keylen)
{
	u64 a, b;

	/* needed for the fallback */
	memcpy(&key->k, inkey, GHASH_BLOCK_SIZE);

	/* perform multiplication by 'x' in GF(2^128) */
	b = get_unaligned_be64(inkey);
	a = get_unaligned_be64(inkey + 8);

	key->a = (a << 1) | (b >> 63);
	key->b = (b << 1) | (a >> 63);

	if (b >> 63)
		key->b ^= 0xc200000000000000UL;

	return 0;
}

static int ghash_setkey(struct crypto_shash *tfm,
			const u8 *inkey, unsigned int keylen)
{
	struct ghash_key *key = crypto_shash_ctx(tfm);

	if (keylen != GHASH_BLOCK_SIZE) {
		crypto_shash_set_flags(tfm, CRYPTO_TFM_RES_BAD_KEY_LEN);
		return -EINVAL;
	}

	return __ghash_setkey(key, inkey, keylen);
}

static struct shash_alg ghash_alg = {
	.base.cra_name		= "ghash",
	.base.cra_driver_name	= "ghash-ce",
	.base.cra_priority	= 200,
	.base.cra_flags		= CRYPTO_ALG_TYPE_SHASH,
	.base.cra_blocksize	= GHASH_BLOCK_SIZE,
	.base.cra_ctxsize	= sizeof(struct ghash_key),
	.base.cra_module	= THIS_MODULE,

	.digestsize		= GHASH_DIGEST_SIZE,
	.init			= ghash_init,
	.update			= ghash_update,
	.final			= ghash_final,
	.setkey			= ghash_setkey,
	.descsize		= sizeof(struct ghash_desc_ctx),
};

static int num_rounds(struct crypto_aes_ctx *ctx)
{
	/*
	 * # of rounds specified by AES:
	 * 128 bit key		10 rounds
	 * 192 bit key		12 rounds
	 * 256 bit key		14 rounds
	 * => n byte key	=> 6 + (n/4) rounds
	 */
	return 6 + ctx->key_length / 4;
}

static int gcm_setkey(struct crypto_aead *tfm, const u8 *inkey,
		      unsigned int keylen)
{
	struct gcm_aes_ctx *ctx = crypto_aead_ctx(tfm);
	u8 key[GHASH_BLOCK_SIZE];
	int ret;

	ret = crypto_aes_expand_key(&ctx->aes_key, inkey, keylen);
	if (ret) {
		tfm->base.crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
		return -EINVAL;
	}

	__aes_arm64_encrypt(ctx->aes_key.key_enc, key, (u8[AES_BLOCK_SIZE]){},
			    num_rounds(&ctx->aes_key));

	return __ghash_setkey(&ctx->ghash_key, key, sizeof(key));
}

static int gcm_setauthsize(struct crypto_aead *tfm, unsigned int authsize)
{
	switch (authsize) {
	case 4:
	case 8:
	case 12 ... 16:
		break;
	default:
		return -EINVAL;
	}
	return 0;
}

static void gcm_update_mac(u64 dg[], const u8 *src, int count, u8 buf[],
			   int *buf_count, struct gcm_aes_ctx *ctx)
{
	if (*buf_count > 0) {
		int buf_added = min(count, GHASH_BLOCK_SIZE - *buf_count);

		memcpy(&buf[*buf_count], src, buf_added);

		*buf_count += buf_added;
		src += buf_added;
		count -= buf_added;
	}

	if (count >= GHASH_BLOCK_SIZE || *buf_count == GHASH_BLOCK_SIZE) {
		int blocks = count / GHASH_BLOCK_SIZE;

		ghash_do_update(blocks, dg, src, &ctx->ghash_key,
				*buf_count ? buf : NULL);

		src += blocks * GHASH_BLOCK_SIZE;
		count %= GHASH_BLOCK_SIZE;
		*buf_count = 0;
	}

	if (count > 0) {
		memcpy(buf, src, count);
		*buf_count = count;
	}
}

static void gcm_calculate_auth_mac(struct aead_request *req, u64 dg[])
{
	struct crypto_aead *aead = crypto_aead_reqtfm(req);
	struct gcm_aes_ctx *ctx = crypto_aead_ctx(aead);
	u8 buf[GHASH_BLOCK_SIZE];
	struct scatter_walk walk;
	u32 len = req->assoclen;
	int buf_count = 0;

	scatterwalk_start(&walk, req->src);

	do {
		u32 n = scatterwalk_clamp(&walk, len);
		u8 *p;

		if (!n) {
			scatterwalk_start(&walk, sg_next(walk.sg));
			n = scatterwalk_clamp(&walk, len);
		}
		p = scatterwalk_map(&walk);

		gcm_update_mac(dg, p, n, buf, &buf_count, ctx);
		len -= n;

		scatterwalk_unmap(p);
		scatterwalk_advance(&walk, n);
		scatterwalk_done(&walk, 0, len);
	} while (len);

	if (buf_count) {
		memset(&buf[buf_count], 0, GHASH_BLOCK_SIZE - buf_count);
		ghash_do_update(1, dg, buf, &ctx->ghash_key, NULL);
	}
}

static void gcm_final(struct aead_request *req, struct gcm_aes_ctx *ctx,
		      u64 dg[], u8 tag[], int cryptlen)
{
	u8 mac[AES_BLOCK_SIZE];
	u128 lengths;

	lengths.a = cpu_to_be64(req->assoclen * 8);
	lengths.b = cpu_to_be64(cryptlen * 8);

	ghash_do_update(1, dg, (void *)&lengths, &ctx->ghash_key, NULL);

	put_unaligned_be64(dg[1], mac);
	put_unaligned_be64(dg[0], mac + 8);

	crypto_xor(tag, mac, AES_BLOCK_SIZE);
}

static int gcm_encrypt(struct aead_request *req)
{
	struct crypto_aead *aead = crypto_aead_reqtfm(req);
	struct gcm_aes_ctx *ctx = crypto_aead_ctx(aead);
	struct skcipher_walk walk;
	u8 iv[AES_BLOCK_SIZE];
	u8 ks[AES_BLOCK_SIZE];
	u8 tag[AES_BLOCK_SIZE];
	u64 dg[2] = {};
	int err;

	if (req->assoclen)
		gcm_calculate_auth_mac(req, dg);

	memcpy(iv, req->iv, GCM_IV_SIZE);
	put_unaligned_be32(1, iv + GCM_IV_SIZE);

	if (likely(may_use_simd())) {
		kernel_neon_begin();

		pmull_gcm_encrypt_block(tag, iv, ctx->aes_key.key_enc,
					num_rounds(&ctx->aes_key));
		put_unaligned_be32(2, iv + GCM_IV_SIZE);
		pmull_gcm_encrypt_block(ks, iv, NULL,
					num_rounds(&ctx->aes_key));
		put_unaligned_be32(3, iv + GCM_IV_SIZE);

		err = skcipher_walk_aead_encrypt(&walk, req, true);

		while (walk.nbytes >= AES_BLOCK_SIZE) {
			int blocks = walk.nbytes / AES_BLOCK_SIZE;

			pmull_gcm_encrypt(blocks, dg, walk.dst.virt.addr,
					  walk.src.virt.addr, &ctx->ghash_key,
					  iv, num_rounds(&ctx->aes_key), ks);

			err = skcipher_walk_done(&walk,
						 walk.nbytes % AES_BLOCK_SIZE);
		}
		kernel_neon_end();
	} else {
		__aes_arm64_encrypt(ctx->aes_key.key_enc, tag, iv,
				    num_rounds(&ctx->aes_key));
		put_unaligned_be32(2, iv + GCM_IV_SIZE);

		err = skcipher_walk_aead_encrypt(&walk, req, true);

		while (walk.nbytes >= AES_BLOCK_SIZE) {
			int blocks = walk.nbytes / AES_BLOCK_SIZE;
			u8 *dst = walk.dst.virt.addr;
			u8 *src = walk.src.virt.addr;

			do {
				__aes_arm64_encrypt(ctx->aes_key.key_enc,
						    ks, iv,
						    num_rounds(&ctx->aes_key));
				crypto_xor_cpy(dst, src, ks, AES_BLOCK_SIZE);
				crypto_inc(iv, AES_BLOCK_SIZE);

				dst += AES_BLOCK_SIZE;
				src += AES_BLOCK_SIZE;
			} while (--blocks > 0);

			ghash_do_update(walk.nbytes / AES_BLOCK_SIZE, dg,
					walk.dst.virt.addr, &ctx->ghash_key,
					NULL);

			err = skcipher_walk_done(&walk,
						 walk.nbytes % AES_BLOCK_SIZE);
		}
		if (walk.nbytes)
			__aes_arm64_encrypt(ctx->aes_key.key_enc, ks, iv,
					    num_rounds(&ctx->aes_key));
	}

	/* handle the tail */
	if (walk.nbytes) {
		u8 buf[GHASH_BLOCK_SIZE];

		crypto_xor_cpy(walk.dst.virt.addr, walk.src.virt.addr, ks,
			       walk.nbytes);

		memcpy(buf, walk.dst.virt.addr, walk.nbytes);
		memset(buf + walk.nbytes, 0, GHASH_BLOCK_SIZE - walk.nbytes);
		ghash_do_update(1, dg, buf, &ctx->ghash_key, NULL);

		err = skcipher_walk_done(&walk, 0);
	}

	if (err)
		return err;

	gcm_final(req, ctx, dg, tag, req->cryptlen);

	/* copy authtag to end of dst */
	scatterwalk_map_and_copy(tag, req->dst, req->assoclen + req->cryptlen,
				 crypto_aead_authsize(aead), 1);

	return 0;
}

static int gcm_decrypt(struct aead_request *req)
{
	struct crypto_aead *aead = crypto_aead_reqtfm(req);
	struct gcm_aes_ctx *ctx = crypto_aead_ctx(aead);
	unsigned int authsize = crypto_aead_authsize(aead);
	struct skcipher_walk walk;
	u8 iv[AES_BLOCK_SIZE];
	u8 tag[AES_BLOCK_SIZE];
	u8 buf[GHASH_BLOCK_SIZE];
	u64 dg[2] = {};
	int err;

	if (req->assoclen)
		gcm_calculate_auth_mac(req, dg);

	memcpy(iv, req->iv, GCM_IV_SIZE);
	put_unaligned_be32(1, iv + GCM_IV_SIZE);

	if (likely(may_use_simd())) {
		kernel_neon_begin();

		pmull_gcm_encrypt_block(tag, iv, ctx->aes_key.key_enc,
					num_rounds(&ctx->aes_key));
		put_unaligned_be32(2, iv + GCM_IV_SIZE);

		err = skcipher_walk_aead_decrypt(&walk, req, true);

		while (walk.nbytes >= AES_BLOCK_SIZE) {
			int blocks = walk.nbytes / AES_BLOCK_SIZE;

			pmull_gcm_decrypt(blocks, dg, walk.dst.virt.addr,
					  walk.src.virt.addr, &ctx->ghash_key,
					  iv, num_rounds(&ctx->aes_key));

			err = skcipher_walk_done(&walk,
						 walk.nbytes % AES_BLOCK_SIZE);
		}
		if (walk.nbytes)
			pmull_gcm_encrypt_block(iv, iv, NULL,
						num_rounds(&ctx->aes_key));

		kernel_neon_end();
	} else {
		__aes_arm64_encrypt(ctx->aes_key.key_enc, tag, iv,
				    num_rounds(&ctx->aes_key));
		put_unaligned_be32(2, iv + GCM_IV_SIZE);

		err = skcipher_walk_aead_decrypt(&walk, req, true);

		while (walk.nbytes >= AES_BLOCK_SIZE) {
			int blocks = walk.nbytes / AES_BLOCK_SIZE;
			u8 *dst = walk.dst.virt.addr;
			u8 *src = walk.src.virt.addr;

			ghash_do_update(blocks, dg, walk.src.virt.addr,
					&ctx->ghash_key, NULL);

			do {
				__aes_arm64_encrypt(ctx->aes_key.key_enc,
						    buf, iv,
						    num_rounds(&ctx->aes_key));
				crypto_xor_cpy(dst, src, buf, AES_BLOCK_SIZE);
				crypto_inc(iv, AES_BLOCK_SIZE);

				dst += AES_BLOCK_SIZE;
				src += AES_BLOCK_SIZE;
			} while (--blocks > 0);

			err = skcipher_walk_done(&walk,
						 walk.nbytes % AES_BLOCK_SIZE);
		}
		if (walk.nbytes)
			__aes_arm64_encrypt(ctx->aes_key.key_enc, iv, iv,
					    num_rounds(&ctx->aes_key));
	}

	/* handle the tail */
	if (walk.nbytes) {
		memcpy(buf, walk.src.virt.addr, walk.nbytes);
		memset(buf + walk.nbytes, 0, GHASH_BLOCK_SIZE - walk.nbytes);
		ghash_do_update(1, dg, buf, &ctx->ghash_key, NULL);

		crypto_xor_cpy(walk.dst.virt.addr, walk.src.virt.addr, iv,
			       walk.nbytes);

		err = skcipher_walk_done(&walk, 0);
	}

	if (err)
		return err;

	gcm_final(req, ctx, dg, tag, req->cryptlen - authsize);

	/* compare calculated auth tag with the stored one */
	scatterwalk_map_and_copy(buf, req->src,
				 req->assoclen + req->cryptlen - authsize,
				 authsize, 0);

	if (crypto_memneq(tag, buf, authsize))
		return -EBADMSG;
	return 0;
}

static struct aead_alg gcm_aes_alg = {
	.ivsize			= GCM_IV_SIZE,
	.chunksize		= AES_BLOCK_SIZE,
	.maxauthsize		= AES_BLOCK_SIZE,
	.setkey			= gcm_setkey,
	.setauthsize		= gcm_setauthsize,
	.encrypt		= gcm_encrypt,
	.decrypt		= gcm_decrypt,

	.base.cra_name		= "gcm(aes)",
	.base.cra_driver_name	= "gcm-aes-ce",
	.base.cra_priority	= 300,
	.base.cra_blocksize	= 1,
	.base.cra_ctxsize	= sizeof(struct gcm_aes_ctx),
	.base.cra_module	= THIS_MODULE,
};

static int __init ghash_ce_mod_init(void)
{
	int ret;

	ret = crypto_register_aead(&gcm_aes_alg);
	if (ret)
		return ret;

	ret = crypto_register_shash(&ghash_alg);
	if (ret)
		crypto_unregister_aead(&gcm_aes_alg);
	return ret;
}

static void __exit ghash_ce_mod_exit(void)
{
	crypto_unregister_shash(&ghash_alg);
	crypto_unregister_aead(&gcm_aes_alg);
}

module_cpu_feature_match(PMULL, ghash_ce_mod_init);
module_exit(ghash_ce_mod_exit);