ghash-ce-glue.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Accelerated GHASH implementation with ARMv8 vmull.p64 instructions.
  4 *
  5 * Copyright (C) 2015 - 2018 Linaro Ltd.
  6 * Copyright (C) 2023 Google LLC.
  7 */
  8
  9#include <asm/hwcap.h>
 10#include <asm/neon.h>
 11#include <crypto/aes.h>
 12#include <crypto/b128ops.h>
 13#include <crypto/gcm.h>
 14#include <crypto/gf128mul.h>
 15#include <crypto/ghash.h>
 16#include <crypto/internal/aead.h>
 17#include <crypto/internal/hash.h>
 18#include <crypto/internal/skcipher.h>
 19#include <crypto/scatterwalk.h>
 20#include <linux/cpufeature.h>
 21#include <linux/errno.h>
 22#include <linux/jump_label.h>
 23#include <linux/kernel.h>
 24#include <linux/module.h>
 25#include <linux/string.h>
 26#include <linux/unaligned.h>
 27
 28MODULE_DESCRIPTION("GHASH hash function using ARMv8 Crypto Extensions");
 29MODULE_AUTHOR("Ard Biesheuvel <ardb@kernel.org>");
 30MODULE_LICENSE("GPL");
 31MODULE_ALIAS_CRYPTO("ghash");
 32MODULE_ALIAS_CRYPTO("gcm(aes)");
 33MODULE_ALIAS_CRYPTO("rfc4106(gcm(aes))");
 34
 35#define RFC4106_NONCE_SIZE	4
 36
 37struct ghash_key {
 38	be128	k;
 39	u64	h[][2];
 40};
 41
 42struct gcm_key {
 43	u64	h[4][2];
 44	u32	rk[AES_MAX_KEYLENGTH_U32];
 45	int	rounds;
 46	u8	nonce[];	// for RFC4106 nonce
 47};
 48
 49struct arm_ghash_desc_ctx {
 50	u64 digest[GHASH_DIGEST_SIZE/sizeof(u64)];
 51};
 52
 53asmlinkage void pmull_ghash_update_p64(int blocks, u64 dg[], const char *src,
 54				       u64 const h[][2], const char *head);
 55
 56asmlinkage void pmull_ghash_update_p8(int blocks, u64 dg[], const char *src,
 57				      u64 const h[][2], const char *head);
 58
 59static __ro_after_init DEFINE_STATIC_KEY_FALSE(use_p64);
 60
 61static int ghash_init(struct shash_desc *desc)
 62{
 63	struct arm_ghash_desc_ctx *ctx = shash_desc_ctx(desc);
 64
 65	*ctx = (struct arm_ghash_desc_ctx){};
 66	return 0;
 67}
 68
 69static void ghash_do_update(int blocks, u64 dg[], const char *src,
 70			    struct ghash_key *key, const char *head)
 71{
 72	kernel_neon_begin();
 73	if (static_branch_likely(&use_p64))
 74		pmull_ghash_update_p64(blocks, dg, src, key->h, head);
 75	else
 76		pmull_ghash_update_p8(blocks, dg, src, key->h, head);
 77	kernel_neon_end();
 78}
 79
 80static int ghash_update(struct shash_desc *desc, const u8 *src,
 81			unsigned int len)
 82{
 83	struct ghash_key *key = crypto_shash_ctx(desc->tfm);
 84	struct arm_ghash_desc_ctx *ctx = shash_desc_ctx(desc);
 85	int blocks;
 86
 87	blocks = len / GHASH_BLOCK_SIZE;
 88	ghash_do_update(blocks, ctx->digest, src, key, NULL);
 89	return len - blocks * GHASH_BLOCK_SIZE;
 90}
 91
 92static int ghash_export(struct shash_desc *desc, void *out)
 93{
 94	struct arm_ghash_desc_ctx *ctx = shash_desc_ctx(desc);
 95	u8 *dst = out;
 96
 97	put_unaligned_be64(ctx->digest[1], dst);
 98	put_unaligned_be64(ctx->digest[0], dst + 8);
 99	return 0;
100}
101
102static int ghash_import(struct shash_desc *desc, const void *in)
103{
104	struct arm_ghash_desc_ctx *ctx = shash_desc_ctx(desc);
105	const u8 *src = in;
106
107	ctx->digest[1] = get_unaligned_be64(src);
108	ctx->digest[0] = get_unaligned_be64(src + 8);
109	return 0;
110}
111
112static int ghash_finup(struct shash_desc *desc, const u8 *src,
113		       unsigned int len, u8 *dst)
114{
115	struct ghash_key *key = crypto_shash_ctx(desc->tfm);
116	struct arm_ghash_desc_ctx *ctx = shash_desc_ctx(desc);
117
118	if (len) {
119		u8 buf[GHASH_BLOCK_SIZE] = {};
120
121		memcpy(buf, src, len);
122		ghash_do_update(1, ctx->digest, buf, key, NULL);
123		memzero_explicit(buf, sizeof(buf));
124	}
125	return ghash_export(desc, dst);
126}
127
128static void ghash_reflect(u64 h[], const be128 *k)
129{
130	u64 carry = be64_to_cpu(k->a) >> 63;
131
132	h[0] = (be64_to_cpu(k->b) << 1) | carry;
133	h[1] = (be64_to_cpu(k->a) << 1) | (be64_to_cpu(k->b) >> 63);
134
135	if (carry)
136		h[1] ^= 0xc200000000000000UL;
137}
138
139static int ghash_setkey(struct crypto_shash *tfm,
140			const u8 *inkey, unsigned int keylen)
141{
142	struct ghash_key *key = crypto_shash_ctx(tfm);
143
144	if (keylen != GHASH_BLOCK_SIZE)
145		return -EINVAL;
146
147	/* needed for the fallback */
148	memcpy(&key->k, inkey, GHASH_BLOCK_SIZE);
149	ghash_reflect(key->h[0], &key->k);
150
151	if (static_branch_likely(&use_p64)) {
152		be128 h = key->k;
153
154		gf128mul_lle(&h, &key->k);
155		ghash_reflect(key->h[1], &h);
156
157		gf128mul_lle(&h, &key->k);
158		ghash_reflect(key->h[2], &h);
159
160		gf128mul_lle(&h, &key->k);
161		ghash_reflect(key->h[3], &h);
162	}
163	return 0;
164}
165
166static struct shash_alg ghash_alg = {
167	.digestsize		= GHASH_DIGEST_SIZE,
168	.init			= ghash_init,
169	.update			= ghash_update,
170	.finup			= ghash_finup,
171	.setkey			= ghash_setkey,
172	.export			= ghash_export,
173	.import			= ghash_import,
174	.descsize		= sizeof(struct arm_ghash_desc_ctx),
175	.statesize		= sizeof(struct ghash_desc_ctx),
176
177	.base.cra_name		= "ghash",
178	.base.cra_driver_name	= "ghash-ce",
179	.base.cra_priority	= 300,
180	.base.cra_flags		= CRYPTO_AHASH_ALG_BLOCK_ONLY,
181	.base.cra_blocksize	= GHASH_BLOCK_SIZE,
182	.base.cra_ctxsize	= sizeof(struct ghash_key) + sizeof(u64[2]),
183	.base.cra_module	= THIS_MODULE,
184};
185
186void pmull_gcm_encrypt(int blocks, u64 dg[], const char *src,
187		       struct gcm_key const *k, char *dst,
188		       const char *iv, int rounds, u32 counter);
189
190void pmull_gcm_enc_final(int blocks, u64 dg[], char *tag,
191			 struct gcm_key const *k, char *head,
192			 const char *iv, int rounds, u32 counter);
193
194void pmull_gcm_decrypt(int bytes, u64 dg[], const char *src,
195		       struct gcm_key const *k, char *dst,
196		       const char *iv, int rounds, u32 counter);
197
198int pmull_gcm_dec_final(int bytes, u64 dg[], char *tag,
199			struct gcm_key const *k, char *head,
200			const char *iv, int rounds, u32 counter,
201			const char *otag, int authsize);
202
203static int gcm_aes_setkey(struct crypto_aead *tfm, const u8 *inkey,
204			  unsigned int keylen)
205{
206	struct gcm_key *ctx = crypto_aead_ctx(tfm);
207	struct crypto_aes_ctx aes_ctx;
208	be128 h, k;
209	int ret;
210
211	ret = aes_expandkey(&aes_ctx, inkey, keylen);
212	if (ret)
213		return -EINVAL;
214
215	aes_encrypt(&aes_ctx, (u8 *)&k, (u8[AES_BLOCK_SIZE]){});
216
217	memcpy(ctx->rk, aes_ctx.key_enc, sizeof(ctx->rk));
218	ctx->rounds = 6 + keylen / 4;
219
220	memzero_explicit(&aes_ctx, sizeof(aes_ctx));
221
222	ghash_reflect(ctx->h[0], &k);
223
224	h = k;
225	gf128mul_lle(&h, &k);
226	ghash_reflect(ctx->h[1], &h);
227
228	gf128mul_lle(&h, &k);
229	ghash_reflect(ctx->h[2], &h);
230
231	gf128mul_lle(&h, &k);
232	ghash_reflect(ctx->h[3], &h);
233
234	return 0;
235}
236
237static int gcm_aes_setauthsize(struct crypto_aead *tfm, unsigned int authsize)
238{
239	return crypto_gcm_check_authsize(authsize);
240}
241
242static void gcm_update_mac(u64 dg[], const u8 *src, int count, u8 buf[],
243			   int *buf_count, struct gcm_key *ctx)
244{
245	if (*buf_count > 0) {
246		int buf_added = min(count, GHASH_BLOCK_SIZE - *buf_count);
247
248		memcpy(&buf[*buf_count], src, buf_added);
249
250		*buf_count += buf_added;
251		src += buf_added;
252		count -= buf_added;
253	}
254
255	if (count >= GHASH_BLOCK_SIZE || *buf_count == GHASH_BLOCK_SIZE) {
256		int blocks = count / GHASH_BLOCK_SIZE;
257
258		pmull_ghash_update_p64(blocks, dg, src, ctx->h,
259				       *buf_count ? buf : NULL);
260
261		src += blocks * GHASH_BLOCK_SIZE;
262		count %= GHASH_BLOCK_SIZE;
263		*buf_count = 0;
264	}
265
266	if (count > 0) {
267		memcpy(buf, src, count);
268		*buf_count = count;
269	}
270}
271
272static void gcm_calculate_auth_mac(struct aead_request *req, u64 dg[], u32 len)
273{
274	struct crypto_aead *aead = crypto_aead_reqtfm(req);
275	struct gcm_key *ctx = crypto_aead_ctx(aead);
276	u8 buf[GHASH_BLOCK_SIZE];
277	struct scatter_walk walk;
278	int buf_count = 0;
279
280	scatterwalk_start(&walk, req->src);
281
282	do {
283		unsigned int n;
284
285		n = scatterwalk_next(&walk, len);
286		gcm_update_mac(dg, walk.addr, n, buf, &buf_count, ctx);
287		scatterwalk_done_src(&walk,  n);
288
289		if (unlikely(len / SZ_4K > (len - n) / SZ_4K)) {
290			kernel_neon_end();
291			kernel_neon_begin();
292		}
293
294		len -= n;
295	} while (len);
296
297	if (buf_count) {
298		memset(&buf[buf_count], 0, GHASH_BLOCK_SIZE - buf_count);
299		pmull_ghash_update_p64(1, dg, buf, ctx->h, NULL);
300	}
301}
302
303static int gcm_encrypt(struct aead_request *req, const u8 *iv, u32 assoclen)
304{
305	struct crypto_aead *aead = crypto_aead_reqtfm(req);
306	struct gcm_key *ctx = crypto_aead_ctx(aead);
307	struct skcipher_walk walk;
308	u8 buf[AES_BLOCK_SIZE];
309	u32 counter = 2;
310	u64 dg[2] = {};
311	be128 lengths;
312	const u8 *src;
313	u8 *tag, *dst;
314	int tail, err;
315
316	err = skcipher_walk_aead_encrypt(&walk, req, false);
317
318	kernel_neon_begin();
319
320	if (assoclen)
321		gcm_calculate_auth_mac(req, dg, assoclen);
322
323	src = walk.src.virt.addr;
324	dst = walk.dst.virt.addr;
325
326	while (walk.nbytes >= AES_BLOCK_SIZE) {
327		int nblocks = walk.nbytes / AES_BLOCK_SIZE;
328
329		pmull_gcm_encrypt(nblocks, dg, src, ctx, dst, iv,
330				  ctx->rounds, counter);
331		counter += nblocks;
332
333		if (walk.nbytes == walk.total) {
334			src += nblocks * AES_BLOCK_SIZE;
335			dst += nblocks * AES_BLOCK_SIZE;
336			break;
337		}
338
339		kernel_neon_end();
340
341		err = skcipher_walk_done(&walk,
342					 walk.nbytes % AES_BLOCK_SIZE);
343		if (err)
344			return err;
345
346		src = walk.src.virt.addr;
347		dst = walk.dst.virt.addr;
348
349		kernel_neon_begin();
350	}
351
352
353	lengths.a = cpu_to_be64(assoclen * 8);
354	lengths.b = cpu_to_be64(req->cryptlen * 8);
355
356	tag = (u8 *)&lengths;
357	tail = walk.nbytes % AES_BLOCK_SIZE;
358
359	/*
360	 * Bounce via a buffer unless we are encrypting in place and src/dst
361	 * are not pointing to the start of the walk buffer. In that case, we
362	 * can do a NEON load/xor/store sequence in place as long as we move
363	 * the plain/ciphertext and keystream to the start of the register. If
364	 * not, do a memcpy() to the end of the buffer so we can reuse the same
365	 * logic.
366	 */
367	if (unlikely(tail && (tail == walk.nbytes || src != dst)))
368		src = memcpy(buf + sizeof(buf) - tail, src, tail);
369
370	pmull_gcm_enc_final(tail, dg, tag, ctx, (u8 *)src, iv,
371			    ctx->rounds, counter);
372	kernel_neon_end();
373
374	if (unlikely(tail && src != dst))
375		memcpy(dst, src, tail);
376
377	if (walk.nbytes) {
378		err = skcipher_walk_done(&walk, 0);
379		if (err)
380			return err;
381	}
382
383	/* copy authtag to end of dst */
384	scatterwalk_map_and_copy(tag, req->dst, req->assoclen + req->cryptlen,
385				 crypto_aead_authsize(aead), 1);
386
387	return 0;
388}
389
390static int gcm_decrypt(struct aead_request *req, const u8 *iv, u32 assoclen)
391{
392	struct crypto_aead *aead = crypto_aead_reqtfm(req);
393	struct gcm_key *ctx = crypto_aead_ctx(aead);
394	int authsize = crypto_aead_authsize(aead);
395	struct skcipher_walk walk;
396	u8 otag[AES_BLOCK_SIZE];
397	u8 buf[AES_BLOCK_SIZE];
398	u32 counter = 2;
399	u64 dg[2] = {};
400	be128 lengths;
401	const u8 *src;
402	u8 *tag, *dst;
403	int tail, err, ret;
404
405	scatterwalk_map_and_copy(otag, req->src,
406				 req->assoclen + req->cryptlen - authsize,
407				 authsize, 0);
408
409	err = skcipher_walk_aead_decrypt(&walk, req, false);
410
411	kernel_neon_begin();
412
413	if (assoclen)
414		gcm_calculate_auth_mac(req, dg, assoclen);
415
416	src = walk.src.virt.addr;
417	dst = walk.dst.virt.addr;
418
419	while (walk.nbytes >= AES_BLOCK_SIZE) {
420		int nblocks = walk.nbytes / AES_BLOCK_SIZE;
421
422		pmull_gcm_decrypt(nblocks, dg, src, ctx, dst, iv,
423				  ctx->rounds, counter);
424		counter += nblocks;
425
426		if (walk.nbytes == walk.total) {
427			src += nblocks * AES_BLOCK_SIZE;
428			dst += nblocks * AES_BLOCK_SIZE;
429			break;
430		}
431
432		kernel_neon_end();
433
434		err = skcipher_walk_done(&walk,
435					 walk.nbytes % AES_BLOCK_SIZE);
436		if (err)
437			return err;
438
439		src = walk.src.virt.addr;
440		dst = walk.dst.virt.addr;
441
442		kernel_neon_begin();
443	}
444
445	lengths.a = cpu_to_be64(assoclen * 8);
446	lengths.b = cpu_to_be64((req->cryptlen - authsize) * 8);
447
448	tag = (u8 *)&lengths;
449	tail = walk.nbytes % AES_BLOCK_SIZE;
450
451	if (unlikely(tail && (tail == walk.nbytes || src != dst)))
452		src = memcpy(buf + sizeof(buf) - tail, src, tail);
453
454	ret = pmull_gcm_dec_final(tail, dg, tag, ctx, (u8 *)src, iv,
455				  ctx->rounds, counter, otag, authsize);
456	kernel_neon_end();
457
458	if (unlikely(tail && src != dst))
459		memcpy(dst, src, tail);
460
461	if (walk.nbytes) {
462		err = skcipher_walk_done(&walk, 0);
463		if (err)
464			return err;
465	}
466
467	return ret ? -EBADMSG : 0;
468}
469
470static int gcm_aes_encrypt(struct aead_request *req)
471{
472	return gcm_encrypt(req, req->iv, req->assoclen);
473}
474
475static int gcm_aes_decrypt(struct aead_request *req)
476{
477	return gcm_decrypt(req, req->iv, req->assoclen);
478}
479
480static int rfc4106_setkey(struct crypto_aead *tfm, const u8 *inkey,
481			  unsigned int keylen)
482{
483	struct gcm_key *ctx = crypto_aead_ctx(tfm);
484	int err;
485
486	keylen -= RFC4106_NONCE_SIZE;
487	err = gcm_aes_setkey(tfm, inkey, keylen);
488	if (err)
489		return err;
490
491	memcpy(ctx->nonce, inkey + keylen, RFC4106_NONCE_SIZE);
492	return 0;
493}
494
495static int rfc4106_setauthsize(struct crypto_aead *tfm, unsigned int authsize)
496{
497	return crypto_rfc4106_check_authsize(authsize);
498}
499
500static int rfc4106_encrypt(struct aead_request *req)
501{
502	struct crypto_aead *aead = crypto_aead_reqtfm(req);
503	struct gcm_key *ctx = crypto_aead_ctx(aead);
504	u8 iv[GCM_AES_IV_SIZE];
505
506	memcpy(iv, ctx->nonce, RFC4106_NONCE_SIZE);
507	memcpy(iv + RFC4106_NONCE_SIZE, req->iv, GCM_RFC4106_IV_SIZE);
508
509	return crypto_ipsec_check_assoclen(req->assoclen) ?:
510	       gcm_encrypt(req, iv, req->assoclen - GCM_RFC4106_IV_SIZE);
511}
512
513static int rfc4106_decrypt(struct aead_request *req)
514{
515	struct crypto_aead *aead = crypto_aead_reqtfm(req);
516	struct gcm_key *ctx = crypto_aead_ctx(aead);
517	u8 iv[GCM_AES_IV_SIZE];
518
519	memcpy(iv, ctx->nonce, RFC4106_NONCE_SIZE);
520	memcpy(iv + RFC4106_NONCE_SIZE, req->iv, GCM_RFC4106_IV_SIZE);
521
522	return crypto_ipsec_check_assoclen(req->assoclen) ?:
523	       gcm_decrypt(req, iv, req->assoclen - GCM_RFC4106_IV_SIZE);
524}
525
526static struct aead_alg gcm_aes_algs[] = {{
527	.ivsize			= GCM_AES_IV_SIZE,
528	.chunksize		= AES_BLOCK_SIZE,
529	.maxauthsize		= AES_BLOCK_SIZE,
530	.setkey			= gcm_aes_setkey,
531	.setauthsize		= gcm_aes_setauthsize,
532	.encrypt		= gcm_aes_encrypt,
533	.decrypt		= gcm_aes_decrypt,
534
535	.base.cra_name		= "gcm(aes)",
536	.base.cra_driver_name	= "gcm-aes-ce",
537	.base.cra_priority	= 400,
538	.base.cra_blocksize	= 1,
539	.base.cra_ctxsize	= sizeof(struct gcm_key),
540	.base.cra_module	= THIS_MODULE,
541}, {
542	.ivsize			= GCM_RFC4106_IV_SIZE,
543	.chunksize		= AES_BLOCK_SIZE,
544	.maxauthsize		= AES_BLOCK_SIZE,
545	.setkey			= rfc4106_setkey,
546	.setauthsize		= rfc4106_setauthsize,
547	.encrypt		= rfc4106_encrypt,
548	.decrypt		= rfc4106_decrypt,
549
550	.base.cra_name		= "rfc4106(gcm(aes))",
551	.base.cra_driver_name	= "rfc4106-gcm-aes-ce",
552	.base.cra_priority	= 400,
553	.base.cra_blocksize	= 1,
554	.base.cra_ctxsize	= sizeof(struct gcm_key) + RFC4106_NONCE_SIZE,
555	.base.cra_module	= THIS_MODULE,
556}};
557
558static int __init ghash_ce_mod_init(void)
559{
560	int err;
561
562	if (!(elf_hwcap & HWCAP_NEON))
563		return -ENODEV;
564
565	if (elf_hwcap2 & HWCAP2_PMULL) {
566		err = crypto_register_aeads(gcm_aes_algs,
567					    ARRAY_SIZE(gcm_aes_algs));
568		if (err)
569			return err;
570		ghash_alg.base.cra_ctxsize += 3 * sizeof(u64[2]);
571		static_branch_enable(&use_p64);
572	}
573
574	err = crypto_register_shash(&ghash_alg);
575	if (err)
576		goto err_aead;
577
578	return 0;
579
580err_aead:
581	if (elf_hwcap2 & HWCAP2_PMULL)
582		crypto_unregister_aeads(gcm_aes_algs,
583					ARRAY_SIZE(gcm_aes_algs));
584	return err;
585}
586
587static void __exit ghash_ce_mod_exit(void)
588{
589	crypto_unregister_shash(&ghash_alg);
590	if (elf_hwcap2 & HWCAP2_PMULL)
591		crypto_unregister_aeads(gcm_aes_algs,
592					ARRAY_SIZE(gcm_aes_algs));
593}
594
595module_init(ghash_ce_mod_init);
596module_exit(ghash_ce_mod_exit);