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 59 asmlinkage void pmull_gcm_decrypt(int bytes, u8 dst[], const u8 src[], 60 u64 const h[][2], u64 dg[], u8 ctr[], 61 u32 const rk[], int rounds, u8 tag[]); 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 *ctx = (struct ghash_desc_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 if (likely(crypto_simd_usable())) { 366 do { 367 const u8 *src = walk.src.virt.addr; 368 u8 *dst = walk.dst.virt.addr; 369 int nbytes = walk.nbytes; 370 371 tag = (u8 *)&lengths; 372 373 if (unlikely(nbytes > 0 && nbytes < AES_BLOCK_SIZE)) { 374 src = dst = memcpy(buf + sizeof(buf) - nbytes, 375 src, nbytes); 376 } else if (nbytes < walk.total) { 377 nbytes &= ~(AES_BLOCK_SIZE - 1); 378 tag = NULL; 379 } 380 381 kernel_neon_begin(); 382 pmull_gcm_encrypt(nbytes, dst, src, ctx->ghash_key.h, 383 dg, iv, ctx->aes_key.key_enc, nrounds, 384 tag); 385 kernel_neon_end(); 386 387 if (unlikely(!nbytes)) 388 break; 389 390 if (unlikely(nbytes > 0 && nbytes < AES_BLOCK_SIZE)) 391 memcpy(walk.dst.virt.addr, 392 buf + sizeof(buf) - nbytes, nbytes); 393 394 err = skcipher_walk_done(&walk, walk.nbytes - nbytes); 395 } while (walk.nbytes); 396 } else { 397 while (walk.nbytes >= AES_BLOCK_SIZE) { 398 int blocks = walk.nbytes / AES_BLOCK_SIZE; 399 const u8 *src = walk.src.virt.addr; 400 u8 *dst = walk.dst.virt.addr; 401 int remaining = blocks; 402 403 do { 404 aes_encrypt(&ctx->aes_key, buf, iv); 405 crypto_xor_cpy(dst, src, buf, AES_BLOCK_SIZE); 406 crypto_inc(iv, AES_BLOCK_SIZE); 407 408 dst += AES_BLOCK_SIZE; 409 src += AES_BLOCK_SIZE; 410 } while (--remaining > 0); 411 412 ghash_do_update(blocks, dg, walk.dst.virt.addr, 413 &ctx->ghash_key, NULL); 414 415 err = skcipher_walk_done(&walk, 416 walk.nbytes % AES_BLOCK_SIZE); 417 } 418 419 /* handle the tail */ 420 if (walk.nbytes) { 421 aes_encrypt(&ctx->aes_key, buf, iv); 422 423 crypto_xor_cpy(walk.dst.virt.addr, walk.src.virt.addr, 424 buf, walk.nbytes); 425 426 memcpy(buf, walk.dst.virt.addr, walk.nbytes); 427 memset(buf + walk.nbytes, 0, sizeof(buf) - walk.nbytes); 428 } 429 430 tag = (u8 *)&lengths; 431 ghash_do_update(1, dg, tag, &ctx->ghash_key, 432 walk.nbytes ? buf : NULL); 433 434 if (walk.nbytes) 435 err = skcipher_walk_done(&walk, 0); 436 437 put_unaligned_be64(dg[1], tag); 438 put_unaligned_be64(dg[0], tag + 8); 439 put_unaligned_be32(1, iv + GCM_IV_SIZE); 440 aes_encrypt(&ctx->aes_key, iv, iv); 441 crypto_xor(tag, iv, AES_BLOCK_SIZE); 442 } 443 444 if (err) 445 return err; 446 447 /* copy authtag to end of dst */ 448 scatterwalk_map_and_copy(tag, req->dst, req->assoclen + req->cryptlen, 449 crypto_aead_authsize(aead), 1); 450 451 return 0; 452 } 453 454 static int gcm_decrypt(struct aead_request *req) 455 { 456 struct crypto_aead *aead = crypto_aead_reqtfm(req); 457 struct gcm_aes_ctx *ctx = crypto_aead_ctx(aead); 458 unsigned int authsize = crypto_aead_authsize(aead); 459 int nrounds = num_rounds(&ctx->aes_key); 460 struct skcipher_walk walk; 461 u8 buf[AES_BLOCK_SIZE]; 462 u8 iv[AES_BLOCK_SIZE]; 463 u64 dg[2] = {}; 464 be128 lengths; 465 u8 *tag; 466 int err; 467 468 lengths.a = cpu_to_be64(req->assoclen * 8); 469 lengths.b = cpu_to_be64((req->cryptlen - authsize) * 8); 470 471 if (req->assoclen) 472 gcm_calculate_auth_mac(req, dg); 473 474 memcpy(iv, req->iv, GCM_IV_SIZE); 475 put_unaligned_be32(2, iv + GCM_IV_SIZE); 476 477 err = skcipher_walk_aead_decrypt(&walk, req, false); 478 479 if (likely(crypto_simd_usable())) { 480 do { 481 const u8 *src = walk.src.virt.addr; 482 u8 *dst = walk.dst.virt.addr; 483 int nbytes = walk.nbytes; 484 485 tag = (u8 *)&lengths; 486 487 if (unlikely(nbytes > 0 && nbytes < AES_BLOCK_SIZE)) { 488 src = dst = memcpy(buf + sizeof(buf) - nbytes, 489 src, nbytes); 490 } else if (nbytes < walk.total) { 491 nbytes &= ~(AES_BLOCK_SIZE - 1); 492 tag = NULL; 493 } 494 495 kernel_neon_begin(); 496 pmull_gcm_decrypt(nbytes, dst, src, ctx->ghash_key.h, 497 dg, iv, ctx->aes_key.key_enc, nrounds, 498 tag); 499 kernel_neon_end(); 500 501 if (unlikely(!nbytes)) 502 break; 503 504 if (unlikely(nbytes > 0 && nbytes < AES_BLOCK_SIZE)) 505 memcpy(walk.dst.virt.addr, 506 buf + sizeof(buf) - nbytes, nbytes); 507 508 err = skcipher_walk_done(&walk, walk.nbytes - nbytes); 509 } while (walk.nbytes); 510 } else { 511 while (walk.nbytes >= AES_BLOCK_SIZE) { 512 int blocks = walk.nbytes / AES_BLOCK_SIZE; 513 const u8 *src = walk.src.virt.addr; 514 u8 *dst = walk.dst.virt.addr; 515 516 ghash_do_update(blocks, dg, walk.src.virt.addr, 517 &ctx->ghash_key, NULL); 518 519 do { 520 aes_encrypt(&ctx->aes_key, buf, iv); 521 crypto_xor_cpy(dst, src, buf, AES_BLOCK_SIZE); 522 crypto_inc(iv, AES_BLOCK_SIZE); 523 524 dst += AES_BLOCK_SIZE; 525 src += AES_BLOCK_SIZE; 526 } while (--blocks > 0); 527 528 err = skcipher_walk_done(&walk, 529 walk.nbytes % AES_BLOCK_SIZE); 530 } 531 532 /* handle the tail */ 533 if (walk.nbytes) { 534 memcpy(buf, walk.src.virt.addr, walk.nbytes); 535 memset(buf + walk.nbytes, 0, sizeof(buf) - walk.nbytes); 536 } 537 538 tag = (u8 *)&lengths; 539 ghash_do_update(1, dg, tag, &ctx->ghash_key, 540 walk.nbytes ? buf : NULL); 541 542 if (walk.nbytes) { 543 aes_encrypt(&ctx->aes_key, buf, iv); 544 545 crypto_xor_cpy(walk.dst.virt.addr, walk.src.virt.addr, 546 buf, walk.nbytes); 547 548 err = skcipher_walk_done(&walk, 0); 549 } 550 551 put_unaligned_be64(dg[1], tag); 552 put_unaligned_be64(dg[0], tag + 8); 553 put_unaligned_be32(1, iv + GCM_IV_SIZE); 554 aes_encrypt(&ctx->aes_key, iv, iv); 555 crypto_xor(tag, iv, AES_BLOCK_SIZE); 556 } 557 558 if (err) 559 return err; 560 561 /* compare calculated auth tag with the stored one */ 562 scatterwalk_map_and_copy(buf, req->src, 563 req->assoclen + req->cryptlen - authsize, 564 authsize, 0); 565 566 if (crypto_memneq(tag, buf, authsize)) 567 return -EBADMSG; 568 return 0; 569 } 570 571 static struct aead_alg gcm_aes_alg = { 572 .ivsize = GCM_IV_SIZE, 573 .chunksize = AES_BLOCK_SIZE, 574 .maxauthsize = AES_BLOCK_SIZE, 575 .setkey = gcm_setkey, 576 .setauthsize = gcm_setauthsize, 577 .encrypt = gcm_encrypt, 578 .decrypt = gcm_decrypt, 579 580 .base.cra_name = "gcm(aes)", 581 .base.cra_driver_name = "gcm-aes-ce", 582 .base.cra_priority = 300, 583 .base.cra_blocksize = 1, 584 .base.cra_ctxsize = sizeof(struct gcm_aes_ctx) + 585 4 * sizeof(u64[2]), 586 .base.cra_module = THIS_MODULE, 587 }; 588 589 static int __init ghash_ce_mod_init(void) 590 { 591 if (!cpu_have_named_feature(ASIMD)) 592 return -ENODEV; 593 594 if (cpu_have_named_feature(PMULL)) 595 return crypto_register_aead(&gcm_aes_alg); 596 597 return crypto_register_shash(&ghash_alg); 598 } 599 600 static void __exit ghash_ce_mod_exit(void) 601 { 602 if (cpu_have_named_feature(PMULL)) 603 crypto_unregister_aead(&gcm_aes_alg); 604 else 605 crypto_unregister_shash(&ghash_alg); 606 } 607 608 static const struct cpu_feature ghash_cpu_feature[] = { 609 { cpu_feature(PMULL) }, { } 610 }; 611 MODULE_DEVICE_TABLE(cpu, ghash_cpu_feature); 612 613 module_init(ghash_ce_mod_init); 614 module_exit(ghash_ce_mod_exit); 615