1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Accelerated GHASH implementation with ARMv8 PMULL instructions.
4  *
5  * Copyright (C) 2014 - 2018 Linaro Ltd. <ard.biesheuvel@linaro.org>
6  */
7 
8 #include <asm/neon.h>
9 #include <asm/simd.h>
10 #include <asm/unaligned.h>
11 #include <crypto/aes.h>
12 #include <crypto/algapi.h>
13 #include <crypto/b128ops.h>
14 #include <crypto/gf128mul.h>
15 #include <crypto/internal/aead.h>
16 #include <crypto/internal/hash.h>
17 #include <crypto/internal/simd.h>
18 #include <crypto/internal/skcipher.h>
19 #include <crypto/scatterwalk.h>
20 #include <linux/cpufeature.h>
21 #include <linux/crypto.h>
22 #include <linux/module.h>
23 
24 MODULE_DESCRIPTION("GHASH and AES-GCM using ARMv8 Crypto Extensions");
25 MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");
26 MODULE_LICENSE("GPL v2");
27 MODULE_ALIAS_CRYPTO("ghash");
28 
29 #define GHASH_BLOCK_SIZE	16
30 #define GHASH_DIGEST_SIZE	16
31 #define GCM_IV_SIZE		12
32 
33 struct ghash_key {
34 	be128			k;
35 	u64			h[][2];
36 };
37 
38 struct ghash_desc_ctx {
39 	u64 digest[GHASH_DIGEST_SIZE/sizeof(u64)];
40 	u8 buf[GHASH_BLOCK_SIZE];
41 	u32 count;
42 };
43 
44 struct gcm_aes_ctx {
45 	struct crypto_aes_ctx	aes_key;
46 	struct ghash_key	ghash_key;
47 };
48 
49 asmlinkage void pmull_ghash_update_p64(int blocks, u64 dg[], const char *src,
50 				       u64 const h[][2], const char *head);
51 
52 asmlinkage void pmull_ghash_update_p8(int blocks, u64 dg[], const char *src,
53 				      u64 const h[][2], const char *head);
54 
55 asmlinkage void pmull_gcm_encrypt(int bytes, u8 dst[], const u8 src[],
56 				  u64 const h[][2], u64 dg[], u8 ctr[],
57 				  u32 const rk[], int rounds, u8 tag[]);
58 asmlinkage int pmull_gcm_decrypt(int bytes, u8 dst[], const u8 src[],
59 				 u64 const h[][2], u64 dg[], u8 ctr[],
60 				 u32 const rk[], int rounds, const u8 l[],
61 				 const u8 tag[], u64 authsize);
62 
63 static int ghash_init(struct shash_desc *desc)
64 {
65 	struct ghash_desc_ctx *ctx = shash_desc_ctx(desc);
66 
67 	*ctx = (struct ghash_desc_ctx){};
68 	return 0;
69 }
70 
71 static void ghash_do_update(int blocks, u64 dg[], const char *src,
72 			    struct ghash_key *key, const char *head)
73 {
74 	be128 dst = { cpu_to_be64(dg[1]), cpu_to_be64(dg[0]) };
75 
76 	do {
77 		const u8 *in = src;
78 
79 		if (head) {
80 			in = head;
81 			blocks++;
82 			head = NULL;
83 		} else {
84 			src += GHASH_BLOCK_SIZE;
85 		}
86 
87 		crypto_xor((u8 *)&dst, in, GHASH_BLOCK_SIZE);
88 		gf128mul_lle(&dst, &key->k);
89 	} while (--blocks);
90 
91 	dg[0] = be64_to_cpu(dst.b);
92 	dg[1] = be64_to_cpu(dst.a);
93 }
94 
95 static __always_inline
96 void ghash_do_simd_update(int blocks, u64 dg[], const char *src,
97 			  struct ghash_key *key, const char *head,
98 			  void (*simd_update)(int blocks, u64 dg[],
99 					      const char *src,
100 					      u64 const h[][2],
101 					      const char *head))
102 {
103 	if (likely(crypto_simd_usable())) {
104 		kernel_neon_begin();
105 		simd_update(blocks, dg, src, key->h, head);
106 		kernel_neon_end();
107 	} else {
108 		ghash_do_update(blocks, dg, src, key, head);
109 	}
110 }
111 
112 /* avoid hogging the CPU for too long */
113 #define MAX_BLOCKS	(SZ_64K / GHASH_BLOCK_SIZE)
114 
115 static int ghash_update(struct shash_desc *desc, const u8 *src,
116 			unsigned int len)
117 {
118 	struct ghash_desc_ctx *ctx = shash_desc_ctx(desc);
119 	unsigned int partial = ctx->count % GHASH_BLOCK_SIZE;
120 
121 	ctx->count += len;
122 
123 	if ((partial + len) >= GHASH_BLOCK_SIZE) {
124 		struct ghash_key *key = crypto_shash_ctx(desc->tfm);
125 		int blocks;
126 
127 		if (partial) {
128 			int p = GHASH_BLOCK_SIZE - partial;
129 
130 			memcpy(ctx->buf + partial, src, p);
131 			src += p;
132 			len -= p;
133 		}
134 
135 		blocks = len / GHASH_BLOCK_SIZE;
136 		len %= GHASH_BLOCK_SIZE;
137 
138 		do {
139 			int chunk = min(blocks, MAX_BLOCKS);
140 
141 			ghash_do_simd_update(chunk, ctx->digest, src, key,
142 					     partial ? ctx->buf : NULL,
143 					     pmull_ghash_update_p8);
144 
145 			blocks -= chunk;
146 			src += chunk * GHASH_BLOCK_SIZE;
147 			partial = 0;
148 		} while (unlikely(blocks > 0));
149 	}
150 	if (len)
151 		memcpy(ctx->buf + partial, src, len);
152 	return 0;
153 }
154 
155 static int ghash_final(struct shash_desc *desc, u8 *dst)
156 {
157 	struct ghash_desc_ctx *ctx = shash_desc_ctx(desc);
158 	unsigned int partial = ctx->count % GHASH_BLOCK_SIZE;
159 
160 	if (partial) {
161 		struct ghash_key *key = crypto_shash_ctx(desc->tfm);
162 
163 		memset(ctx->buf + partial, 0, GHASH_BLOCK_SIZE - partial);
164 
165 		ghash_do_simd_update(1, ctx->digest, ctx->buf, key, NULL,
166 				     pmull_ghash_update_p8);
167 	}
168 	put_unaligned_be64(ctx->digest[1], dst);
169 	put_unaligned_be64(ctx->digest[0], dst + 8);
170 
171 	memzero_explicit(ctx, sizeof(*ctx));
172 	return 0;
173 }
174 
175 static void ghash_reflect(u64 h[], const be128 *k)
176 {
177 	u64 carry = be64_to_cpu(k->a) & BIT(63) ? 1 : 0;
178 
179 	h[0] = (be64_to_cpu(k->b) << 1) | carry;
180 	h[1] = (be64_to_cpu(k->a) << 1) | (be64_to_cpu(k->b) >> 63);
181 
182 	if (carry)
183 		h[1] ^= 0xc200000000000000UL;
184 }
185 
186 static int ghash_setkey(struct crypto_shash *tfm,
187 			const u8 *inkey, unsigned int keylen)
188 {
189 	struct ghash_key *key = crypto_shash_ctx(tfm);
190 
191 	if (keylen != GHASH_BLOCK_SIZE)
192 		return -EINVAL;
193 
194 	/* needed for the fallback */
195 	memcpy(&key->k, inkey, GHASH_BLOCK_SIZE);
196 
197 	ghash_reflect(key->h[0], &key->k);
198 	return 0;
199 }
200 
201 static struct shash_alg ghash_alg = {
202 	.base.cra_name		= "ghash",
203 	.base.cra_driver_name	= "ghash-neon",
204 	.base.cra_priority	= 150,
205 	.base.cra_blocksize	= GHASH_BLOCK_SIZE,
206 	.base.cra_ctxsize	= sizeof(struct ghash_key) + sizeof(u64[2]),
207 	.base.cra_module	= THIS_MODULE,
208 
209 	.digestsize		= GHASH_DIGEST_SIZE,
210 	.init			= ghash_init,
211 	.update			= ghash_update,
212 	.final			= ghash_final,
213 	.setkey			= ghash_setkey,
214 	.descsize		= sizeof(struct ghash_desc_ctx),
215 };
216 
217 static int num_rounds(struct crypto_aes_ctx *ctx)
218 {
219 	/*
220 	 * # of rounds specified by AES:
221 	 * 128 bit key		10 rounds
222 	 * 192 bit key		12 rounds
223 	 * 256 bit key		14 rounds
224 	 * => n byte key	=> 6 + (n/4) rounds
225 	 */
226 	return 6 + ctx->key_length / 4;
227 }
228 
229 static int gcm_setkey(struct crypto_aead *tfm, const u8 *inkey,
230 		      unsigned int keylen)
231 {
232 	struct gcm_aes_ctx *ctx = crypto_aead_ctx(tfm);
233 	u8 key[GHASH_BLOCK_SIZE];
234 	be128 h;
235 	int ret;
236 
237 	ret = aes_expandkey(&ctx->aes_key, inkey, keylen);
238 	if (ret)
239 		return -EINVAL;
240 
241 	aes_encrypt(&ctx->aes_key, key, (u8[AES_BLOCK_SIZE]){});
242 
243 	/* needed for the fallback */
244 	memcpy(&ctx->ghash_key.k, key, GHASH_BLOCK_SIZE);
245 
246 	ghash_reflect(ctx->ghash_key.h[0], &ctx->ghash_key.k);
247 
248 	h = ctx->ghash_key.k;
249 	gf128mul_lle(&h, &ctx->ghash_key.k);
250 	ghash_reflect(ctx->ghash_key.h[1], &h);
251 
252 	gf128mul_lle(&h, &ctx->ghash_key.k);
253 	ghash_reflect(ctx->ghash_key.h[2], &h);
254 
255 	gf128mul_lle(&h, &ctx->ghash_key.k);
256 	ghash_reflect(ctx->ghash_key.h[3], &h);
257 
258 	return 0;
259 }
260 
261 static int gcm_setauthsize(struct crypto_aead *tfm, unsigned int authsize)
262 {
263 	switch (authsize) {
264 	case 4:
265 	case 8:
266 	case 12 ... 16:
267 		break;
268 	default:
269 		return -EINVAL;
270 	}
271 	return 0;
272 }
273 
274 static void gcm_update_mac(u64 dg[], const u8 *src, int count, u8 buf[],
275 			   int *buf_count, struct gcm_aes_ctx *ctx)
276 {
277 	if (*buf_count > 0) {
278 		int buf_added = min(count, GHASH_BLOCK_SIZE - *buf_count);
279 
280 		memcpy(&buf[*buf_count], src, buf_added);
281 
282 		*buf_count += buf_added;
283 		src += buf_added;
284 		count -= buf_added;
285 	}
286 
287 	if (count >= GHASH_BLOCK_SIZE || *buf_count == GHASH_BLOCK_SIZE) {
288 		int blocks = count / GHASH_BLOCK_SIZE;
289 
290 		ghash_do_simd_update(blocks, dg, src, &ctx->ghash_key,
291 				     *buf_count ? buf : NULL,
292 				     pmull_ghash_update_p64);
293 
294 		src += blocks * GHASH_BLOCK_SIZE;
295 		count %= GHASH_BLOCK_SIZE;
296 		*buf_count = 0;
297 	}
298 
299 	if (count > 0) {
300 		memcpy(buf, src, count);
301 		*buf_count = count;
302 	}
303 }
304 
305 static void gcm_calculate_auth_mac(struct aead_request *req, u64 dg[])
306 {
307 	struct crypto_aead *aead = crypto_aead_reqtfm(req);
308 	struct gcm_aes_ctx *ctx = crypto_aead_ctx(aead);
309 	u8 buf[GHASH_BLOCK_SIZE];
310 	struct scatter_walk walk;
311 	u32 len = req->assoclen;
312 	int buf_count = 0;
313 
314 	scatterwalk_start(&walk, req->src);
315 
316 	do {
317 		u32 n = scatterwalk_clamp(&walk, len);
318 		u8 *p;
319 
320 		if (!n) {
321 			scatterwalk_start(&walk, sg_next(walk.sg));
322 			n = scatterwalk_clamp(&walk, len);
323 		}
324 		p = scatterwalk_map(&walk);
325 
326 		gcm_update_mac(dg, p, n, buf, &buf_count, ctx);
327 		len -= n;
328 
329 		scatterwalk_unmap(p);
330 		scatterwalk_advance(&walk, n);
331 		scatterwalk_done(&walk, 0, len);
332 	} while (len);
333 
334 	if (buf_count) {
335 		memset(&buf[buf_count], 0, GHASH_BLOCK_SIZE - buf_count);
336 		ghash_do_simd_update(1, dg, buf, &ctx->ghash_key, NULL,
337 				     pmull_ghash_update_p64);
338 	}
339 }
340 
341 static int gcm_encrypt(struct aead_request *req)
342 {
343 	struct crypto_aead *aead = crypto_aead_reqtfm(req);
344 	struct gcm_aes_ctx *ctx = crypto_aead_ctx(aead);
345 	int nrounds = num_rounds(&ctx->aes_key);
346 	struct skcipher_walk walk;
347 	u8 buf[AES_BLOCK_SIZE];
348 	u8 iv[AES_BLOCK_SIZE];
349 	u64 dg[2] = {};
350 	be128 lengths;
351 	u8 *tag;
352 	int err;
353 
354 	lengths.a = cpu_to_be64(req->assoclen * 8);
355 	lengths.b = cpu_to_be64(req->cryptlen * 8);
356 
357 	if (req->assoclen)
358 		gcm_calculate_auth_mac(req, dg);
359 
360 	memcpy(iv, req->iv, GCM_IV_SIZE);
361 	put_unaligned_be32(2, iv + GCM_IV_SIZE);
362 
363 	err = skcipher_walk_aead_encrypt(&walk, req, false);
364 
365 	do {
366 		const u8 *src = walk.src.virt.addr;
367 		u8 *dst = walk.dst.virt.addr;
368 		int nbytes = walk.nbytes;
369 
370 		tag = (u8 *)&lengths;
371 
372 		if (unlikely(nbytes > 0 && nbytes < AES_BLOCK_SIZE)) {
373 			src = dst = memcpy(buf + sizeof(buf) - nbytes,
374 					   src, nbytes);
375 		} else if (nbytes < walk.total) {
376 			nbytes &= ~(AES_BLOCK_SIZE - 1);
377 			tag = NULL;
378 		}
379 
380 		kernel_neon_begin();
381 		pmull_gcm_encrypt(nbytes, dst, src, ctx->ghash_key.h,
382 				  dg, iv, ctx->aes_key.key_enc, nrounds,
383 				  tag);
384 		kernel_neon_end();
385 
386 		if (unlikely(!nbytes))
387 			break;
388 
389 		if (unlikely(nbytes > 0 && nbytes < AES_BLOCK_SIZE))
390 			memcpy(walk.dst.virt.addr,
391 			       buf + sizeof(buf) - nbytes, nbytes);
392 
393 		err = skcipher_walk_done(&walk, walk.nbytes - nbytes);
394 	} while (walk.nbytes);
395 
396 	if (err)
397 		return err;
398 
399 	/* copy authtag to end of dst */
400 	scatterwalk_map_and_copy(tag, req->dst, req->assoclen + req->cryptlen,
401 				 crypto_aead_authsize(aead), 1);
402 
403 	return 0;
404 }
405 
406 static int gcm_decrypt(struct aead_request *req)
407 {
408 	struct crypto_aead *aead = crypto_aead_reqtfm(req);
409 	struct gcm_aes_ctx *ctx = crypto_aead_ctx(aead);
410 	unsigned int authsize = crypto_aead_authsize(aead);
411 	int nrounds = num_rounds(&ctx->aes_key);
412 	struct skcipher_walk walk;
413 	u8 otag[AES_BLOCK_SIZE];
414 	u8 buf[AES_BLOCK_SIZE];
415 	u8 iv[AES_BLOCK_SIZE];
416 	u64 dg[2] = {};
417 	be128 lengths;
418 	u8 *tag;
419 	int ret;
420 	int err;
421 
422 	lengths.a = cpu_to_be64(req->assoclen * 8);
423 	lengths.b = cpu_to_be64((req->cryptlen - authsize) * 8);
424 
425 	if (req->assoclen)
426 		gcm_calculate_auth_mac(req, dg);
427 
428 	memcpy(iv, req->iv, GCM_IV_SIZE);
429 	put_unaligned_be32(2, iv + GCM_IV_SIZE);
430 
431 	scatterwalk_map_and_copy(otag, req->src,
432 				 req->assoclen + req->cryptlen - authsize,
433 				 authsize, 0);
434 
435 	err = skcipher_walk_aead_decrypt(&walk, req, false);
436 
437 	do {
438 		const u8 *src = walk.src.virt.addr;
439 		u8 *dst = walk.dst.virt.addr;
440 		int nbytes = walk.nbytes;
441 
442 		tag = (u8 *)&lengths;
443 
444 		if (unlikely(nbytes > 0 && nbytes < AES_BLOCK_SIZE)) {
445 			src = dst = memcpy(buf + sizeof(buf) - nbytes,
446 					   src, nbytes);
447 		} else if (nbytes < walk.total) {
448 			nbytes &= ~(AES_BLOCK_SIZE - 1);
449 			tag = NULL;
450 		}
451 
452 		kernel_neon_begin();
453 		ret = pmull_gcm_decrypt(nbytes, dst, src, ctx->ghash_key.h,
454 					dg, iv, ctx->aes_key.key_enc,
455 					nrounds, tag, otag, authsize);
456 		kernel_neon_end();
457 
458 		if (unlikely(!nbytes))
459 			break;
460 
461 		if (unlikely(nbytes > 0 && nbytes < AES_BLOCK_SIZE))
462 			memcpy(walk.dst.virt.addr,
463 			       buf + sizeof(buf) - nbytes, nbytes);
464 
465 		err = skcipher_walk_done(&walk, walk.nbytes - nbytes);
466 	} while (walk.nbytes);
467 
468 	if (err)
469 		return err;
470 
471 	return ret ? -EBADMSG : 0;
472 }
473 
474 static struct aead_alg gcm_aes_alg = {
475 	.ivsize			= GCM_IV_SIZE,
476 	.chunksize		= AES_BLOCK_SIZE,
477 	.maxauthsize		= AES_BLOCK_SIZE,
478 	.setkey			= gcm_setkey,
479 	.setauthsize		= gcm_setauthsize,
480 	.encrypt		= gcm_encrypt,
481 	.decrypt		= gcm_decrypt,
482 
483 	.base.cra_name		= "gcm(aes)",
484 	.base.cra_driver_name	= "gcm-aes-ce",
485 	.base.cra_priority	= 300,
486 	.base.cra_blocksize	= 1,
487 	.base.cra_ctxsize	= sizeof(struct gcm_aes_ctx) +
488 				  4 * sizeof(u64[2]),
489 	.base.cra_module	= THIS_MODULE,
490 };
491 
492 static int __init ghash_ce_mod_init(void)
493 {
494 	if (!cpu_have_named_feature(ASIMD))
495 		return -ENODEV;
496 
497 	if (cpu_have_named_feature(PMULL))
498 		return crypto_register_aead(&gcm_aes_alg);
499 
500 	return crypto_register_shash(&ghash_alg);
501 }
502 
503 static void __exit ghash_ce_mod_exit(void)
504 {
505 	if (cpu_have_named_feature(PMULL))
506 		crypto_unregister_aead(&gcm_aes_alg);
507 	else
508 		crypto_unregister_shash(&ghash_alg);
509 }
510 
511 static const struct cpu_feature ghash_cpu_feature[] = {
512 	{ cpu_feature(PMULL) }, { }
513 };
514 MODULE_DEVICE_TABLE(cpu, ghash_cpu_feature);
515 
516 module_init(ghash_ce_mod_init);
517 module_exit(ghash_ce_mod_exit);
518