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 <crypto/aes.h>
9 #include <crypto/b128ops.h>
10 #include <crypto/gcm.h>
11 #include <crypto/ghash.h>
12 #include <crypto/gf128mul.h>
13 #include <crypto/internal/aead.h>
14 #include <crypto/internal/hash.h>
15 #include <crypto/internal/skcipher.h>
16 #include <crypto/scatterwalk.h>
17 #include <linux/cpufeature.h>
18 #include <linux/errno.h>
19 #include <linux/kernel.h>
20 #include <linux/module.h>
21 #include <linux/string.h>
22 #include <linux/unaligned.h>
23
24 #include <asm/simd.h>
25
26 MODULE_DESCRIPTION("GHASH and AES-GCM using ARMv8 Crypto Extensions");
27 MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");
28 MODULE_LICENSE("GPL v2");
29 MODULE_ALIAS_CRYPTO("ghash");
30
31 #define RFC4106_NONCE_SIZE 4
32
33 struct ghash_key {
34 be128 k;
35 u64 h[][2];
36 };
37
38 struct arm_ghash_desc_ctx {
39 u64 digest[GHASH_DIGEST_SIZE/sizeof(u64)];
40 };
41
42 struct gcm_aes_ctx {
43 struct crypto_aes_ctx aes_key;
44 u8 nonce[RFC4106_NONCE_SIZE];
45 struct ghash_key ghash_key;
46 };
47
48 asmlinkage void pmull_ghash_update_p64(int blocks, u64 dg[], const char *src,
49 u64 const h[][2], const char *head);
50
51 asmlinkage void pmull_ghash_update_p8(int blocks, u64 dg[], const char *src,
52 u64 const h[][2], const char *head);
53
54 asmlinkage void pmull_gcm_encrypt(int bytes, u8 dst[], const u8 src[],
55 u64 const h[][2], u64 dg[], u8 ctr[],
56 u32 const rk[], int rounds, u8 tag[]);
57 asmlinkage int pmull_gcm_decrypt(int bytes, u8 dst[], const u8 src[],
58 u64 const h[][2], u64 dg[], u8 ctr[],
59 u32 const rk[], int rounds, const u8 l[],
60 const u8 tag[], u64 authsize);
61
ghash_init(struct shash_desc * desc)62 static int ghash_init(struct shash_desc *desc)
63 {
64 struct arm_ghash_desc_ctx *ctx = shash_desc_ctx(desc);
65
66 *ctx = (struct arm_ghash_desc_ctx){};
67 return 0;
68 }
69
70 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))71 void ghash_do_simd_update(int blocks, u64 dg[], const char *src,
72 struct ghash_key *key, const char *head,
73 void (*simd_update)(int blocks, u64 dg[],
74 const char *src,
75 u64 const h[][2],
76 const char *head))
77 {
78 scoped_ksimd()
79 simd_update(blocks, dg, src, key->h, head);
80 }
81
82 /* avoid hogging the CPU for too long */
83 #define MAX_BLOCKS (SZ_64K / GHASH_BLOCK_SIZE)
84
ghash_update(struct shash_desc * desc,const u8 * src,unsigned int len)85 static int ghash_update(struct shash_desc *desc, const u8 *src,
86 unsigned int len)
87 {
88 struct arm_ghash_desc_ctx *ctx = shash_desc_ctx(desc);
89 struct ghash_key *key = crypto_shash_ctx(desc->tfm);
90 int blocks;
91
92 blocks = len / GHASH_BLOCK_SIZE;
93 len -= blocks * GHASH_BLOCK_SIZE;
94
95 do {
96 int chunk = min(blocks, MAX_BLOCKS);
97
98 ghash_do_simd_update(chunk, ctx->digest, src, key, NULL,
99 pmull_ghash_update_p8);
100 blocks -= chunk;
101 src += chunk * GHASH_BLOCK_SIZE;
102 } while (unlikely(blocks > 0));
103 return len;
104 }
105
ghash_export(struct shash_desc * desc,void * out)106 static int ghash_export(struct shash_desc *desc, void *out)
107 {
108 struct arm_ghash_desc_ctx *ctx = shash_desc_ctx(desc);
109 u8 *dst = out;
110
111 put_unaligned_be64(ctx->digest[1], dst);
112 put_unaligned_be64(ctx->digest[0], dst + 8);
113 return 0;
114 }
115
ghash_import(struct shash_desc * desc,const void * in)116 static int ghash_import(struct shash_desc *desc, const void *in)
117 {
118 struct arm_ghash_desc_ctx *ctx = shash_desc_ctx(desc);
119 const u8 *src = in;
120
121 ctx->digest[1] = get_unaligned_be64(src);
122 ctx->digest[0] = get_unaligned_be64(src + 8);
123 return 0;
124 }
125
ghash_finup(struct shash_desc * desc,const u8 * src,unsigned int len,u8 * dst)126 static int ghash_finup(struct shash_desc *desc, const u8 *src,
127 unsigned int len, u8 *dst)
128 {
129 struct arm_ghash_desc_ctx *ctx = shash_desc_ctx(desc);
130 struct ghash_key *key = crypto_shash_ctx(desc->tfm);
131
132 if (len) {
133 u8 buf[GHASH_BLOCK_SIZE] = {};
134
135 memcpy(buf, src, len);
136 ghash_do_simd_update(1, ctx->digest, src, key, NULL,
137 pmull_ghash_update_p8);
138 memzero_explicit(buf, sizeof(buf));
139 }
140 return ghash_export(desc, dst);
141 }
142
ghash_reflect(u64 h[],const be128 * k)143 static void ghash_reflect(u64 h[], const be128 *k)
144 {
145 u64 carry = be64_to_cpu(k->a) & BIT(63) ? 1 : 0;
146
147 h[0] = (be64_to_cpu(k->b) << 1) | carry;
148 h[1] = (be64_to_cpu(k->a) << 1) | (be64_to_cpu(k->b) >> 63);
149
150 if (carry)
151 h[1] ^= 0xc200000000000000UL;
152 }
153
ghash_setkey(struct crypto_shash * tfm,const u8 * inkey,unsigned int keylen)154 static int ghash_setkey(struct crypto_shash *tfm,
155 const u8 *inkey, unsigned int keylen)
156 {
157 struct ghash_key *key = crypto_shash_ctx(tfm);
158
159 if (keylen != GHASH_BLOCK_SIZE)
160 return -EINVAL;
161
162 /* needed for the fallback */
163 memcpy(&key->k, inkey, GHASH_BLOCK_SIZE);
164
165 ghash_reflect(key->h[0], &key->k);
166 return 0;
167 }
168
169 static struct shash_alg ghash_alg = {
170 .base.cra_name = "ghash",
171 .base.cra_driver_name = "ghash-neon",
172 .base.cra_priority = 150,
173 .base.cra_flags = CRYPTO_AHASH_ALG_BLOCK_ONLY,
174 .base.cra_blocksize = GHASH_BLOCK_SIZE,
175 .base.cra_ctxsize = sizeof(struct ghash_key) + sizeof(u64[2]),
176 .base.cra_module = THIS_MODULE,
177
178 .digestsize = GHASH_DIGEST_SIZE,
179 .init = ghash_init,
180 .update = ghash_update,
181 .finup = ghash_finup,
182 .setkey = ghash_setkey,
183 .export = ghash_export,
184 .import = ghash_import,
185 .descsize = sizeof(struct arm_ghash_desc_ctx),
186 .statesize = sizeof(struct ghash_desc_ctx),
187 };
188
num_rounds(struct crypto_aes_ctx * ctx)189 static int num_rounds(struct crypto_aes_ctx *ctx)
190 {
191 /*
192 * # of rounds specified by AES:
193 * 128 bit key 10 rounds
194 * 192 bit key 12 rounds
195 * 256 bit key 14 rounds
196 * => n byte key => 6 + (n/4) rounds
197 */
198 return 6 + ctx->key_length / 4;
199 }
200
gcm_aes_setkey(struct crypto_aead * tfm,const u8 * inkey,unsigned int keylen)201 static int gcm_aes_setkey(struct crypto_aead *tfm, const u8 *inkey,
202 unsigned int keylen)
203 {
204 struct gcm_aes_ctx *ctx = crypto_aead_ctx(tfm);
205 u8 key[GHASH_BLOCK_SIZE];
206 be128 h;
207 int ret;
208
209 ret = aes_expandkey(&ctx->aes_key, inkey, keylen);
210 if (ret)
211 return -EINVAL;
212
213 aes_encrypt(&ctx->aes_key, key, (u8[AES_BLOCK_SIZE]){});
214
215 /* needed for the fallback */
216 memcpy(&ctx->ghash_key.k, key, GHASH_BLOCK_SIZE);
217
218 ghash_reflect(ctx->ghash_key.h[0], &ctx->ghash_key.k);
219
220 h = ctx->ghash_key.k;
221 gf128mul_lle(&h, &ctx->ghash_key.k);
222 ghash_reflect(ctx->ghash_key.h[1], &h);
223
224 gf128mul_lle(&h, &ctx->ghash_key.k);
225 ghash_reflect(ctx->ghash_key.h[2], &h);
226
227 gf128mul_lle(&h, &ctx->ghash_key.k);
228 ghash_reflect(ctx->ghash_key.h[3], &h);
229
230 return 0;
231 }
232
gcm_aes_setauthsize(struct crypto_aead * tfm,unsigned int authsize)233 static int gcm_aes_setauthsize(struct crypto_aead *tfm, unsigned int authsize)
234 {
235 return crypto_gcm_check_authsize(authsize);
236 }
237
gcm_update_mac(u64 dg[],const u8 * src,int count,u8 buf[],int * buf_count,struct gcm_aes_ctx * ctx)238 static void gcm_update_mac(u64 dg[], const u8 *src, int count, u8 buf[],
239 int *buf_count, struct gcm_aes_ctx *ctx)
240 {
241 if (*buf_count > 0) {
242 int buf_added = min(count, GHASH_BLOCK_SIZE - *buf_count);
243
244 memcpy(&buf[*buf_count], src, buf_added);
245
246 *buf_count += buf_added;
247 src += buf_added;
248 count -= buf_added;
249 }
250
251 if (count >= GHASH_BLOCK_SIZE || *buf_count == GHASH_BLOCK_SIZE) {
252 int blocks = count / GHASH_BLOCK_SIZE;
253
254 ghash_do_simd_update(blocks, dg, src, &ctx->ghash_key,
255 *buf_count ? buf : NULL,
256 pmull_ghash_update_p64);
257
258 src += blocks * GHASH_BLOCK_SIZE;
259 count %= GHASH_BLOCK_SIZE;
260 *buf_count = 0;
261 }
262
263 if (count > 0) {
264 memcpy(buf, src, count);
265 *buf_count = count;
266 }
267 }
268
gcm_calculate_auth_mac(struct aead_request * req,u64 dg[],u32 len)269 static void gcm_calculate_auth_mac(struct aead_request *req, u64 dg[], u32 len)
270 {
271 struct crypto_aead *aead = crypto_aead_reqtfm(req);
272 struct gcm_aes_ctx *ctx = crypto_aead_ctx(aead);
273 u8 buf[GHASH_BLOCK_SIZE];
274 struct scatter_walk walk;
275 int buf_count = 0;
276
277 scatterwalk_start(&walk, req->src);
278
279 do {
280 unsigned int n;
281
282 n = scatterwalk_next(&walk, len);
283 gcm_update_mac(dg, walk.addr, n, buf, &buf_count, ctx);
284 scatterwalk_done_src(&walk, n);
285 len -= n;
286 } while (len);
287
288 if (buf_count) {
289 memset(&buf[buf_count], 0, GHASH_BLOCK_SIZE - buf_count);
290 ghash_do_simd_update(1, dg, buf, &ctx->ghash_key, NULL,
291 pmull_ghash_update_p64);
292 }
293 }
294
gcm_encrypt(struct aead_request * req,char * iv,int assoclen)295 static int gcm_encrypt(struct aead_request *req, char *iv, int assoclen)
296 {
297 struct crypto_aead *aead = crypto_aead_reqtfm(req);
298 struct gcm_aes_ctx *ctx = crypto_aead_ctx(aead);
299 int nrounds = num_rounds(&ctx->aes_key);
300 struct skcipher_walk walk;
301 u8 buf[AES_BLOCK_SIZE];
302 u64 dg[2] = {};
303 be128 lengths;
304 u8 *tag;
305 int err;
306
307 lengths.a = cpu_to_be64(assoclen * 8);
308 lengths.b = cpu_to_be64(req->cryptlen * 8);
309
310 if (assoclen)
311 gcm_calculate_auth_mac(req, dg, assoclen);
312
313 put_unaligned_be32(2, iv + GCM_AES_IV_SIZE);
314
315 err = skcipher_walk_aead_encrypt(&walk, req, false);
316
317 do {
318 const u8 *src = walk.src.virt.addr;
319 u8 *dst = walk.dst.virt.addr;
320 int nbytes = walk.nbytes;
321
322 tag = (u8 *)&lengths;
323
324 if (unlikely(nbytes > 0 && nbytes < AES_BLOCK_SIZE)) {
325 src = dst = memcpy(buf + sizeof(buf) - nbytes,
326 src, nbytes);
327 } else if (nbytes < walk.total) {
328 nbytes &= ~(AES_BLOCK_SIZE - 1);
329 tag = NULL;
330 }
331
332 scoped_ksimd()
333 pmull_gcm_encrypt(nbytes, dst, src, ctx->ghash_key.h,
334 dg, iv, ctx->aes_key.key_enc, nrounds,
335 tag);
336
337 if (unlikely(!nbytes))
338 break;
339
340 if (unlikely(nbytes > 0 && nbytes < AES_BLOCK_SIZE))
341 memcpy(walk.dst.virt.addr,
342 buf + sizeof(buf) - nbytes, nbytes);
343
344 err = skcipher_walk_done(&walk, walk.nbytes - nbytes);
345 } while (walk.nbytes);
346
347 if (err)
348 return err;
349
350 /* copy authtag to end of dst */
351 scatterwalk_map_and_copy(tag, req->dst, req->assoclen + req->cryptlen,
352 crypto_aead_authsize(aead), 1);
353
354 return 0;
355 }
356
gcm_decrypt(struct aead_request * req,char * iv,int assoclen)357 static int gcm_decrypt(struct aead_request *req, char *iv, int assoclen)
358 {
359 struct crypto_aead *aead = crypto_aead_reqtfm(req);
360 struct gcm_aes_ctx *ctx = crypto_aead_ctx(aead);
361 unsigned int authsize = crypto_aead_authsize(aead);
362 int nrounds = num_rounds(&ctx->aes_key);
363 struct skcipher_walk walk;
364 u8 otag[AES_BLOCK_SIZE];
365 u8 buf[AES_BLOCK_SIZE];
366 u64 dg[2] = {};
367 be128 lengths;
368 u8 *tag;
369 int ret;
370 int err;
371
372 lengths.a = cpu_to_be64(assoclen * 8);
373 lengths.b = cpu_to_be64((req->cryptlen - authsize) * 8);
374
375 if (assoclen)
376 gcm_calculate_auth_mac(req, dg, assoclen);
377
378 put_unaligned_be32(2, iv + GCM_AES_IV_SIZE);
379
380 scatterwalk_map_and_copy(otag, req->src,
381 req->assoclen + req->cryptlen - authsize,
382 authsize, 0);
383
384 err = skcipher_walk_aead_decrypt(&walk, req, false);
385
386 do {
387 const u8 *src = walk.src.virt.addr;
388 u8 *dst = walk.dst.virt.addr;
389 int nbytes = walk.nbytes;
390
391 tag = (u8 *)&lengths;
392
393 if (unlikely(nbytes > 0 && nbytes < AES_BLOCK_SIZE)) {
394 src = dst = memcpy(buf + sizeof(buf) - nbytes,
395 src, nbytes);
396 } else if (nbytes < walk.total) {
397 nbytes &= ~(AES_BLOCK_SIZE - 1);
398 tag = NULL;
399 }
400
401 scoped_ksimd()
402 ret = pmull_gcm_decrypt(nbytes, dst, src,
403 ctx->ghash_key.h,
404 dg, iv, ctx->aes_key.key_enc,
405 nrounds, tag, otag, authsize);
406
407 if (unlikely(!nbytes))
408 break;
409
410 if (unlikely(nbytes > 0 && nbytes < AES_BLOCK_SIZE))
411 memcpy(walk.dst.virt.addr,
412 buf + sizeof(buf) - nbytes, nbytes);
413
414 err = skcipher_walk_done(&walk, walk.nbytes - nbytes);
415 } while (walk.nbytes);
416
417 if (err)
418 return err;
419
420 return ret ? -EBADMSG : 0;
421 }
422
gcm_aes_encrypt(struct aead_request * req)423 static int gcm_aes_encrypt(struct aead_request *req)
424 {
425 u8 iv[AES_BLOCK_SIZE];
426
427 memcpy(iv, req->iv, GCM_AES_IV_SIZE);
428 return gcm_encrypt(req, iv, req->assoclen);
429 }
430
gcm_aes_decrypt(struct aead_request * req)431 static int gcm_aes_decrypt(struct aead_request *req)
432 {
433 u8 iv[AES_BLOCK_SIZE];
434
435 memcpy(iv, req->iv, GCM_AES_IV_SIZE);
436 return gcm_decrypt(req, iv, req->assoclen);
437 }
438
rfc4106_setkey(struct crypto_aead * tfm,const u8 * inkey,unsigned int keylen)439 static int rfc4106_setkey(struct crypto_aead *tfm, const u8 *inkey,
440 unsigned int keylen)
441 {
442 struct gcm_aes_ctx *ctx = crypto_aead_ctx(tfm);
443 int err;
444
445 keylen -= RFC4106_NONCE_SIZE;
446 err = gcm_aes_setkey(tfm, inkey, keylen);
447 if (err)
448 return err;
449
450 memcpy(ctx->nonce, inkey + keylen, RFC4106_NONCE_SIZE);
451 return 0;
452 }
453
rfc4106_setauthsize(struct crypto_aead * tfm,unsigned int authsize)454 static int rfc4106_setauthsize(struct crypto_aead *tfm, unsigned int authsize)
455 {
456 return crypto_rfc4106_check_authsize(authsize);
457 }
458
rfc4106_encrypt(struct aead_request * req)459 static int rfc4106_encrypt(struct aead_request *req)
460 {
461 struct crypto_aead *aead = crypto_aead_reqtfm(req);
462 struct gcm_aes_ctx *ctx = crypto_aead_ctx(aead);
463 u8 iv[AES_BLOCK_SIZE];
464
465 memcpy(iv, ctx->nonce, RFC4106_NONCE_SIZE);
466 memcpy(iv + RFC4106_NONCE_SIZE, req->iv, GCM_RFC4106_IV_SIZE);
467
468 return crypto_ipsec_check_assoclen(req->assoclen) ?:
469 gcm_encrypt(req, iv, req->assoclen - GCM_RFC4106_IV_SIZE);
470 }
471
rfc4106_decrypt(struct aead_request * req)472 static int rfc4106_decrypt(struct aead_request *req)
473 {
474 struct crypto_aead *aead = crypto_aead_reqtfm(req);
475 struct gcm_aes_ctx *ctx = crypto_aead_ctx(aead);
476 u8 iv[AES_BLOCK_SIZE];
477
478 memcpy(iv, ctx->nonce, RFC4106_NONCE_SIZE);
479 memcpy(iv + RFC4106_NONCE_SIZE, req->iv, GCM_RFC4106_IV_SIZE);
480
481 return crypto_ipsec_check_assoclen(req->assoclen) ?:
482 gcm_decrypt(req, iv, req->assoclen - GCM_RFC4106_IV_SIZE);
483 }
484
485 static struct aead_alg gcm_aes_algs[] = {{
486 .ivsize = GCM_AES_IV_SIZE,
487 .chunksize = AES_BLOCK_SIZE,
488 .maxauthsize = AES_BLOCK_SIZE,
489 .setkey = gcm_aes_setkey,
490 .setauthsize = gcm_aes_setauthsize,
491 .encrypt = gcm_aes_encrypt,
492 .decrypt = gcm_aes_decrypt,
493
494 .base.cra_name = "gcm(aes)",
495 .base.cra_driver_name = "gcm-aes-ce",
496 .base.cra_priority = 300,
497 .base.cra_blocksize = 1,
498 .base.cra_ctxsize = sizeof(struct gcm_aes_ctx) +
499 4 * sizeof(u64[2]),
500 .base.cra_module = THIS_MODULE,
501 }, {
502 .ivsize = GCM_RFC4106_IV_SIZE,
503 .chunksize = AES_BLOCK_SIZE,
504 .maxauthsize = AES_BLOCK_SIZE,
505 .setkey = rfc4106_setkey,
506 .setauthsize = rfc4106_setauthsize,
507 .encrypt = rfc4106_encrypt,
508 .decrypt = rfc4106_decrypt,
509
510 .base.cra_name = "rfc4106(gcm(aes))",
511 .base.cra_driver_name = "rfc4106-gcm-aes-ce",
512 .base.cra_priority = 300,
513 .base.cra_blocksize = 1,
514 .base.cra_ctxsize = sizeof(struct gcm_aes_ctx) +
515 4 * sizeof(u64[2]),
516 .base.cra_module = THIS_MODULE,
517 }};
518
ghash_ce_mod_init(void)519 static int __init ghash_ce_mod_init(void)
520 {
521 if (!cpu_have_named_feature(ASIMD))
522 return -ENODEV;
523
524 if (cpu_have_named_feature(PMULL))
525 return crypto_register_aeads(gcm_aes_algs,
526 ARRAY_SIZE(gcm_aes_algs));
527
528 return crypto_register_shash(&ghash_alg);
529 }
530
ghash_ce_mod_exit(void)531 static void __exit ghash_ce_mod_exit(void)
532 {
533 if (cpu_have_named_feature(PMULL))
534 crypto_unregister_aeads(gcm_aes_algs, ARRAY_SIZE(gcm_aes_algs));
535 else
536 crypto_unregister_shash(&ghash_alg);
537 }
538
539 static const struct cpu_feature __maybe_unused ghash_cpu_feature[] = {
540 { cpu_feature(PMULL) }, { }
541 };
542 MODULE_DEVICE_TABLE(cpu, ghash_cpu_feature);
543
544 module_init(ghash_ce_mod_init);
545 module_exit(ghash_ce_mod_exit);
546