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 <linux/unaligned.h>
11 #include <crypto/aes.h>
12 #include <crypto/gcm.h>
13 #include <crypto/algapi.h>
14 #include <crypto/b128ops.h>
15 #include <crypto/gf128mul.h>
16 #include <crypto/internal/aead.h>
17 #include <crypto/internal/hash.h>
18 #include <crypto/internal/simd.h>
19 #include <crypto/internal/skcipher.h>
20 #include <crypto/scatterwalk.h>
21 #include <linux/cpufeature.h>
22 #include <linux/crypto.h>
23 #include <linux/module.h>
24
25 MODULE_DESCRIPTION("GHASH and AES-GCM using ARMv8 Crypto Extensions");
26 MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");
27 MODULE_LICENSE("GPL v2");
28 MODULE_ALIAS_CRYPTO("ghash");
29
30 #define GHASH_BLOCK_SIZE 16
31 #define GHASH_DIGEST_SIZE 16
32
33 #define RFC4106_NONCE_SIZE 4
34
35 struct ghash_key {
36 be128 k;
37 u64 h[][2];
38 };
39
40 struct ghash_desc_ctx {
41 u64 digest[GHASH_DIGEST_SIZE/sizeof(u64)];
42 u8 buf[GHASH_BLOCK_SIZE];
43 u32 count;
44 };
45
46 struct gcm_aes_ctx {
47 struct crypto_aes_ctx aes_key;
48 u8 nonce[RFC4106_NONCE_SIZE];
49 struct ghash_key ghash_key;
50 };
51
52 asmlinkage void pmull_ghash_update_p64(int blocks, u64 dg[], const char *src,
53 u64 const h[][2], const char *head);
54
55 asmlinkage void pmull_ghash_update_p8(int blocks, u64 dg[], const char *src,
56 u64 const h[][2], const char *head);
57
58 asmlinkage void pmull_gcm_encrypt(int bytes, u8 dst[], const u8 src[],
59 u64 const h[][2], u64 dg[], u8 ctr[],
60 u32 const rk[], int rounds, u8 tag[]);
61 asmlinkage int pmull_gcm_decrypt(int bytes, u8 dst[], const u8 src[],
62 u64 const h[][2], u64 dg[], u8 ctr[],
63 u32 const rk[], int rounds, const u8 l[],
64 const u8 tag[], u64 authsize);
65
ghash_init(struct shash_desc * desc)66 static int ghash_init(struct shash_desc *desc)
67 {
68 struct ghash_desc_ctx *ctx = shash_desc_ctx(desc);
69
70 *ctx = (struct ghash_desc_ctx){};
71 return 0;
72 }
73
ghash_do_update(int blocks,u64 dg[],const char * src,struct ghash_key * key,const char * head)74 static void ghash_do_update(int blocks, u64 dg[], const char *src,
75 struct ghash_key *key, const char *head)
76 {
77 be128 dst = { cpu_to_be64(dg[1]), cpu_to_be64(dg[0]) };
78
79 do {
80 const u8 *in = src;
81
82 if (head) {
83 in = head;
84 blocks++;
85 head = NULL;
86 } else {
87 src += GHASH_BLOCK_SIZE;
88 }
89
90 crypto_xor((u8 *)&dst, in, GHASH_BLOCK_SIZE);
91 gf128mul_lle(&dst, &key->k);
92 } while (--blocks);
93
94 dg[0] = be64_to_cpu(dst.b);
95 dg[1] = be64_to_cpu(dst.a);
96 }
97
98 static __always_inline
ghash_do_simd_update(int blocks,u64 dg[],const char * src,struct ghash_key * key,const char * head,void (* simd_update)(int blocks,u64 dg[],const char * src,u64 const h[][2],const char * head))99 void ghash_do_simd_update(int blocks, u64 dg[], const char *src,
100 struct ghash_key *key, const char *head,
101 void (*simd_update)(int blocks, u64 dg[],
102 const char *src,
103 u64 const h[][2],
104 const char *head))
105 {
106 if (likely(crypto_simd_usable())) {
107 kernel_neon_begin();
108 simd_update(blocks, dg, src, key->h, head);
109 kernel_neon_end();
110 } else {
111 ghash_do_update(blocks, dg, src, key, head);
112 }
113 }
114
115 /* avoid hogging the CPU for too long */
116 #define MAX_BLOCKS (SZ_64K / GHASH_BLOCK_SIZE)
117
ghash_update(struct shash_desc * desc,const u8 * src,unsigned int len)118 static int ghash_update(struct shash_desc *desc, const u8 *src,
119 unsigned int len)
120 {
121 struct ghash_desc_ctx *ctx = shash_desc_ctx(desc);
122 unsigned int partial = ctx->count % GHASH_BLOCK_SIZE;
123
124 ctx->count += len;
125
126 if ((partial + len) >= GHASH_BLOCK_SIZE) {
127 struct ghash_key *key = crypto_shash_ctx(desc->tfm);
128 int blocks;
129
130 if (partial) {
131 int p = GHASH_BLOCK_SIZE - partial;
132
133 memcpy(ctx->buf + partial, src, p);
134 src += p;
135 len -= p;
136 }
137
138 blocks = len / GHASH_BLOCK_SIZE;
139 len %= GHASH_BLOCK_SIZE;
140
141 do {
142 int chunk = min(blocks, MAX_BLOCKS);
143
144 ghash_do_simd_update(chunk, ctx->digest, src, key,
145 partial ? ctx->buf : NULL,
146 pmull_ghash_update_p8);
147
148 blocks -= chunk;
149 src += chunk * GHASH_BLOCK_SIZE;
150 partial = 0;
151 } while (unlikely(blocks > 0));
152 }
153 if (len)
154 memcpy(ctx->buf + partial, src, len);
155 return 0;
156 }
157
ghash_final(struct shash_desc * desc,u8 * dst)158 static int ghash_final(struct shash_desc *desc, u8 *dst)
159 {
160 struct ghash_desc_ctx *ctx = shash_desc_ctx(desc);
161 unsigned int partial = ctx->count % GHASH_BLOCK_SIZE;
162
163 if (partial) {
164 struct ghash_key *key = crypto_shash_ctx(desc->tfm);
165
166 memset(ctx->buf + partial, 0, GHASH_BLOCK_SIZE - partial);
167
168 ghash_do_simd_update(1, ctx->digest, ctx->buf, key, NULL,
169 pmull_ghash_update_p8);
170 }
171 put_unaligned_be64(ctx->digest[1], dst);
172 put_unaligned_be64(ctx->digest[0], dst + 8);
173
174 memzero_explicit(ctx, sizeof(*ctx));
175 return 0;
176 }
177
ghash_reflect(u64 h[],const be128 * k)178 static void ghash_reflect(u64 h[], const be128 *k)
179 {
180 u64 carry = be64_to_cpu(k->a) & BIT(63) ? 1 : 0;
181
182 h[0] = (be64_to_cpu(k->b) << 1) | carry;
183 h[1] = (be64_to_cpu(k->a) << 1) | (be64_to_cpu(k->b) >> 63);
184
185 if (carry)
186 h[1] ^= 0xc200000000000000UL;
187 }
188
ghash_setkey(struct crypto_shash * tfm,const u8 * inkey,unsigned int keylen)189 static int ghash_setkey(struct crypto_shash *tfm,
190 const u8 *inkey, unsigned int keylen)
191 {
192 struct ghash_key *key = crypto_shash_ctx(tfm);
193
194 if (keylen != GHASH_BLOCK_SIZE)
195 return -EINVAL;
196
197 /* needed for the fallback */
198 memcpy(&key->k, inkey, GHASH_BLOCK_SIZE);
199
200 ghash_reflect(key->h[0], &key->k);
201 return 0;
202 }
203
204 static struct shash_alg ghash_alg = {
205 .base.cra_name = "ghash",
206 .base.cra_driver_name = "ghash-neon",
207 .base.cra_priority = 150,
208 .base.cra_blocksize = GHASH_BLOCK_SIZE,
209 .base.cra_ctxsize = sizeof(struct ghash_key) + sizeof(u64[2]),
210 .base.cra_module = THIS_MODULE,
211
212 .digestsize = GHASH_DIGEST_SIZE,
213 .init = ghash_init,
214 .update = ghash_update,
215 .final = ghash_final,
216 .setkey = ghash_setkey,
217 .descsize = sizeof(struct ghash_desc_ctx),
218 };
219
num_rounds(struct crypto_aes_ctx * ctx)220 static int num_rounds(struct crypto_aes_ctx *ctx)
221 {
222 /*
223 * # of rounds specified by AES:
224 * 128 bit key 10 rounds
225 * 192 bit key 12 rounds
226 * 256 bit key 14 rounds
227 * => n byte key => 6 + (n/4) rounds
228 */
229 return 6 + ctx->key_length / 4;
230 }
231
gcm_aes_setkey(struct crypto_aead * tfm,const u8 * inkey,unsigned int keylen)232 static int gcm_aes_setkey(struct crypto_aead *tfm, const u8 *inkey,
233 unsigned int keylen)
234 {
235 struct gcm_aes_ctx *ctx = crypto_aead_ctx(tfm);
236 u8 key[GHASH_BLOCK_SIZE];
237 be128 h;
238 int ret;
239
240 ret = aes_expandkey(&ctx->aes_key, inkey, keylen);
241 if (ret)
242 return -EINVAL;
243
244 aes_encrypt(&ctx->aes_key, key, (u8[AES_BLOCK_SIZE]){});
245
246 /* needed for the fallback */
247 memcpy(&ctx->ghash_key.k, key, GHASH_BLOCK_SIZE);
248
249 ghash_reflect(ctx->ghash_key.h[0], &ctx->ghash_key.k);
250
251 h = ctx->ghash_key.k;
252 gf128mul_lle(&h, &ctx->ghash_key.k);
253 ghash_reflect(ctx->ghash_key.h[1], &h);
254
255 gf128mul_lle(&h, &ctx->ghash_key.k);
256 ghash_reflect(ctx->ghash_key.h[2], &h);
257
258 gf128mul_lle(&h, &ctx->ghash_key.k);
259 ghash_reflect(ctx->ghash_key.h[3], &h);
260
261 return 0;
262 }
263
gcm_aes_setauthsize(struct crypto_aead * tfm,unsigned int authsize)264 static int gcm_aes_setauthsize(struct crypto_aead *tfm, unsigned int authsize)
265 {
266 return crypto_gcm_check_authsize(authsize);
267 }
268
gcm_update_mac(u64 dg[],const u8 * src,int count,u8 buf[],int * buf_count,struct gcm_aes_ctx * ctx)269 static void gcm_update_mac(u64 dg[], const u8 *src, int count, u8 buf[],
270 int *buf_count, struct gcm_aes_ctx *ctx)
271 {
272 if (*buf_count > 0) {
273 int buf_added = min(count, GHASH_BLOCK_SIZE - *buf_count);
274
275 memcpy(&buf[*buf_count], src, buf_added);
276
277 *buf_count += buf_added;
278 src += buf_added;
279 count -= buf_added;
280 }
281
282 if (count >= GHASH_BLOCK_SIZE || *buf_count == GHASH_BLOCK_SIZE) {
283 int blocks = count / GHASH_BLOCK_SIZE;
284
285 ghash_do_simd_update(blocks, dg, src, &ctx->ghash_key,
286 *buf_count ? buf : NULL,
287 pmull_ghash_update_p64);
288
289 src += blocks * GHASH_BLOCK_SIZE;
290 count %= GHASH_BLOCK_SIZE;
291 *buf_count = 0;
292 }
293
294 if (count > 0) {
295 memcpy(buf, src, count);
296 *buf_count = count;
297 }
298 }
299
gcm_calculate_auth_mac(struct aead_request * req,u64 dg[],u32 len)300 static void gcm_calculate_auth_mac(struct aead_request *req, u64 dg[], u32 len)
301 {
302 struct crypto_aead *aead = crypto_aead_reqtfm(req);
303 struct gcm_aes_ctx *ctx = crypto_aead_ctx(aead);
304 u8 buf[GHASH_BLOCK_SIZE];
305 struct scatter_walk walk;
306 int buf_count = 0;
307
308 scatterwalk_start(&walk, req->src);
309
310 do {
311 unsigned int n;
312
313 n = scatterwalk_next(&walk, len);
314 gcm_update_mac(dg, walk.addr, n, buf, &buf_count, ctx);
315 scatterwalk_done_src(&walk, n);
316 len -= n;
317 } while (len);
318
319 if (buf_count) {
320 memset(&buf[buf_count], 0, GHASH_BLOCK_SIZE - buf_count);
321 ghash_do_simd_update(1, dg, buf, &ctx->ghash_key, NULL,
322 pmull_ghash_update_p64);
323 }
324 }
325
gcm_encrypt(struct aead_request * req,char * iv,int assoclen)326 static int gcm_encrypt(struct aead_request *req, char *iv, int assoclen)
327 {
328 struct crypto_aead *aead = crypto_aead_reqtfm(req);
329 struct gcm_aes_ctx *ctx = crypto_aead_ctx(aead);
330 int nrounds = num_rounds(&ctx->aes_key);
331 struct skcipher_walk walk;
332 u8 buf[AES_BLOCK_SIZE];
333 u64 dg[2] = {};
334 be128 lengths;
335 u8 *tag;
336 int err;
337
338 lengths.a = cpu_to_be64(assoclen * 8);
339 lengths.b = cpu_to_be64(req->cryptlen * 8);
340
341 if (assoclen)
342 gcm_calculate_auth_mac(req, dg, assoclen);
343
344 put_unaligned_be32(2, iv + GCM_AES_IV_SIZE);
345
346 err = skcipher_walk_aead_encrypt(&walk, req, false);
347
348 do {
349 const u8 *src = walk.src.virt.addr;
350 u8 *dst = walk.dst.virt.addr;
351 int nbytes = walk.nbytes;
352
353 tag = (u8 *)&lengths;
354
355 if (unlikely(nbytes > 0 && nbytes < AES_BLOCK_SIZE)) {
356 src = dst = memcpy(buf + sizeof(buf) - nbytes,
357 src, nbytes);
358 } else if (nbytes < walk.total) {
359 nbytes &= ~(AES_BLOCK_SIZE - 1);
360 tag = NULL;
361 }
362
363 kernel_neon_begin();
364 pmull_gcm_encrypt(nbytes, dst, src, ctx->ghash_key.h,
365 dg, iv, ctx->aes_key.key_enc, nrounds,
366 tag);
367 kernel_neon_end();
368
369 if (unlikely(!nbytes))
370 break;
371
372 if (unlikely(nbytes > 0 && nbytes < AES_BLOCK_SIZE))
373 memcpy(walk.dst.virt.addr,
374 buf + sizeof(buf) - nbytes, nbytes);
375
376 err = skcipher_walk_done(&walk, walk.nbytes - nbytes);
377 } while (walk.nbytes);
378
379 if (err)
380 return err;
381
382 /* copy authtag to end of dst */
383 scatterwalk_map_and_copy(tag, req->dst, req->assoclen + req->cryptlen,
384 crypto_aead_authsize(aead), 1);
385
386 return 0;
387 }
388
gcm_decrypt(struct aead_request * req,char * iv,int assoclen)389 static int gcm_decrypt(struct aead_request *req, char *iv, int assoclen)
390 {
391 struct crypto_aead *aead = crypto_aead_reqtfm(req);
392 struct gcm_aes_ctx *ctx = crypto_aead_ctx(aead);
393 unsigned int authsize = crypto_aead_authsize(aead);
394 int nrounds = num_rounds(&ctx->aes_key);
395 struct skcipher_walk walk;
396 u8 otag[AES_BLOCK_SIZE];
397 u8 buf[AES_BLOCK_SIZE];
398 u64 dg[2] = {};
399 be128 lengths;
400 u8 *tag;
401 int ret;
402 int err;
403
404 lengths.a = cpu_to_be64(assoclen * 8);
405 lengths.b = cpu_to_be64((req->cryptlen - authsize) * 8);
406
407 if (assoclen)
408 gcm_calculate_auth_mac(req, dg, assoclen);
409
410 put_unaligned_be32(2, iv + GCM_AES_IV_SIZE);
411
412 scatterwalk_map_and_copy(otag, req->src,
413 req->assoclen + req->cryptlen - authsize,
414 authsize, 0);
415
416 err = skcipher_walk_aead_decrypt(&walk, req, false);
417
418 do {
419 const u8 *src = walk.src.virt.addr;
420 u8 *dst = walk.dst.virt.addr;
421 int nbytes = walk.nbytes;
422
423 tag = (u8 *)&lengths;
424
425 if (unlikely(nbytes > 0 && nbytes < AES_BLOCK_SIZE)) {
426 src = dst = memcpy(buf + sizeof(buf) - nbytes,
427 src, nbytes);
428 } else if (nbytes < walk.total) {
429 nbytes &= ~(AES_BLOCK_SIZE - 1);
430 tag = NULL;
431 }
432
433 kernel_neon_begin();
434 ret = pmull_gcm_decrypt(nbytes, dst, src, ctx->ghash_key.h,
435 dg, iv, ctx->aes_key.key_enc,
436 nrounds, tag, otag, authsize);
437 kernel_neon_end();
438
439 if (unlikely(!nbytes))
440 break;
441
442 if (unlikely(nbytes > 0 && nbytes < AES_BLOCK_SIZE))
443 memcpy(walk.dst.virt.addr,
444 buf + sizeof(buf) - nbytes, nbytes);
445
446 err = skcipher_walk_done(&walk, walk.nbytes - nbytes);
447 } while (walk.nbytes);
448
449 if (err)
450 return err;
451
452 return ret ? -EBADMSG : 0;
453 }
454
gcm_aes_encrypt(struct aead_request * req)455 static int gcm_aes_encrypt(struct aead_request *req)
456 {
457 u8 iv[AES_BLOCK_SIZE];
458
459 memcpy(iv, req->iv, GCM_AES_IV_SIZE);
460 return gcm_encrypt(req, iv, req->assoclen);
461 }
462
gcm_aes_decrypt(struct aead_request * req)463 static int gcm_aes_decrypt(struct aead_request *req)
464 {
465 u8 iv[AES_BLOCK_SIZE];
466
467 memcpy(iv, req->iv, GCM_AES_IV_SIZE);
468 return gcm_decrypt(req, iv, req->assoclen);
469 }
470
rfc4106_setkey(struct crypto_aead * tfm,const u8 * inkey,unsigned int keylen)471 static int rfc4106_setkey(struct crypto_aead *tfm, const u8 *inkey,
472 unsigned int keylen)
473 {
474 struct gcm_aes_ctx *ctx = crypto_aead_ctx(tfm);
475 int err;
476
477 keylen -= RFC4106_NONCE_SIZE;
478 err = gcm_aes_setkey(tfm, inkey, keylen);
479 if (err)
480 return err;
481
482 memcpy(ctx->nonce, inkey + keylen, RFC4106_NONCE_SIZE);
483 return 0;
484 }
485
rfc4106_setauthsize(struct crypto_aead * tfm,unsigned int authsize)486 static int rfc4106_setauthsize(struct crypto_aead *tfm, unsigned int authsize)
487 {
488 return crypto_rfc4106_check_authsize(authsize);
489 }
490
rfc4106_encrypt(struct aead_request * req)491 static int rfc4106_encrypt(struct aead_request *req)
492 {
493 struct crypto_aead *aead = crypto_aead_reqtfm(req);
494 struct gcm_aes_ctx *ctx = crypto_aead_ctx(aead);
495 u8 iv[AES_BLOCK_SIZE];
496
497 memcpy(iv, ctx->nonce, RFC4106_NONCE_SIZE);
498 memcpy(iv + RFC4106_NONCE_SIZE, req->iv, GCM_RFC4106_IV_SIZE);
499
500 return crypto_ipsec_check_assoclen(req->assoclen) ?:
501 gcm_encrypt(req, iv, req->assoclen - GCM_RFC4106_IV_SIZE);
502 }
503
rfc4106_decrypt(struct aead_request * req)504 static int rfc4106_decrypt(struct aead_request *req)
505 {
506 struct crypto_aead *aead = crypto_aead_reqtfm(req);
507 struct gcm_aes_ctx *ctx = crypto_aead_ctx(aead);
508 u8 iv[AES_BLOCK_SIZE];
509
510 memcpy(iv, ctx->nonce, RFC4106_NONCE_SIZE);
511 memcpy(iv + RFC4106_NONCE_SIZE, req->iv, GCM_RFC4106_IV_SIZE);
512
513 return crypto_ipsec_check_assoclen(req->assoclen) ?:
514 gcm_decrypt(req, iv, req->assoclen - GCM_RFC4106_IV_SIZE);
515 }
516
517 static struct aead_alg gcm_aes_algs[] = {{
518 .ivsize = GCM_AES_IV_SIZE,
519 .chunksize = AES_BLOCK_SIZE,
520 .maxauthsize = AES_BLOCK_SIZE,
521 .setkey = gcm_aes_setkey,
522 .setauthsize = gcm_aes_setauthsize,
523 .encrypt = gcm_aes_encrypt,
524 .decrypt = gcm_aes_decrypt,
525
526 .base.cra_name = "gcm(aes)",
527 .base.cra_driver_name = "gcm-aes-ce",
528 .base.cra_priority = 300,
529 .base.cra_blocksize = 1,
530 .base.cra_ctxsize = sizeof(struct gcm_aes_ctx) +
531 4 * sizeof(u64[2]),
532 .base.cra_module = THIS_MODULE,
533 }, {
534 .ivsize = GCM_RFC4106_IV_SIZE,
535 .chunksize = AES_BLOCK_SIZE,
536 .maxauthsize = AES_BLOCK_SIZE,
537 .setkey = rfc4106_setkey,
538 .setauthsize = rfc4106_setauthsize,
539 .encrypt = rfc4106_encrypt,
540 .decrypt = rfc4106_decrypt,
541
542 .base.cra_name = "rfc4106(gcm(aes))",
543 .base.cra_driver_name = "rfc4106-gcm-aes-ce",
544 .base.cra_priority = 300,
545 .base.cra_blocksize = 1,
546 .base.cra_ctxsize = sizeof(struct gcm_aes_ctx) +
547 4 * sizeof(u64[2]),
548 .base.cra_module = THIS_MODULE,
549 }};
550
ghash_ce_mod_init(void)551 static int __init ghash_ce_mod_init(void)
552 {
553 if (!cpu_have_named_feature(ASIMD))
554 return -ENODEV;
555
556 if (cpu_have_named_feature(PMULL))
557 return crypto_register_aeads(gcm_aes_algs,
558 ARRAY_SIZE(gcm_aes_algs));
559
560 return crypto_register_shash(&ghash_alg);
561 }
562
ghash_ce_mod_exit(void)563 static void __exit ghash_ce_mod_exit(void)
564 {
565 if (cpu_have_named_feature(PMULL))
566 crypto_unregister_aeads(gcm_aes_algs, ARRAY_SIZE(gcm_aes_algs));
567 else
568 crypto_unregister_shash(&ghash_alg);
569 }
570
571 static const struct cpu_feature __maybe_unused ghash_cpu_feature[] = {
572 { cpu_feature(PMULL) }, { }
573 };
574 MODULE_DEVICE_TABLE(cpu, ghash_cpu_feature);
575
576 module_init(ghash_ce_mod_init);
577 module_exit(ghash_ce_mod_exit);
578