arch/arm64/crypto/aes-ce-ccm-glue.c

   1 /*
   2  * aes-ccm-glue.c - AES-CCM transform for ARMv8 with Crypto Extensions
   3  *
   4  * Copyright (C) 2013 - 2017 Linaro Ltd <ard.biesheuvel@linaro.org>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  */
  10
  11 #include <asm/neon.h>
  12 #include <asm/simd.h>
  13 #include <asm/unaligned.h>
  14 #include <crypto/aes.h>
  15 #include <crypto/scatterwalk.h>
  16 #include <crypto/internal/aead.h>
  17 #include <crypto/internal/skcipher.h>
  18 #include <linux/module.h>
  19
  20 #include "aes-ce-setkey.h"
  21
  22 static int num_rounds(struct crypto_aes_ctx *ctx)
  23 {
  24         /*
  25          * # of rounds specified by AES:
  26          * 128 bit key          10 rounds
  27          * 192 bit key          12 rounds
  28          * 256 bit key          14 rounds
  29          * => n byte key        => 6 + (n/4) rounds
  30          */
  31         return 6 + ctx->key_length / 4;
  32 }
  33
  34 asmlinkage void ce_aes_ccm_auth_data(u8 mac[], u8 const in[], u32 abytes,
  35                                      u32 *macp, u32 const rk[], u32 rounds);
  36
  37 asmlinkage void ce_aes_ccm_encrypt(u8 out[], u8 const in[], u32 cbytes,
  38                                    u32 const rk[], u32 rounds, u8 mac[],
  39                                    u8 ctr[]);
  40
  41 asmlinkage void ce_aes_ccm_decrypt(u8 out[], u8 const in[], u32 cbytes,
  42                                    u32 const rk[], u32 rounds, u8 mac[],
  43                                    u8 ctr[]);
  44
  45 asmlinkage void ce_aes_ccm_final(u8 mac[], u8 const ctr[], u32 const rk[],
  46                                  u32 rounds);
  47
  48 asmlinkage void __aes_arm64_encrypt(u32 *rk, u8 *out, const u8 *in, int rounds);
  49
  50 static int ccm_setkey(struct crypto_aead *tfm, const u8 *in_key,
  51                       unsigned int key_len)
  52 {
  53         struct crypto_aes_ctx *ctx = crypto_aead_ctx(tfm);
  54         int ret;
  55
  56         ret = ce_aes_expandkey(ctx, in_key, key_len);
  57         if (!ret)
  58                 return 0;
  59
  60         tfm->base.crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
  61         return -EINVAL;
  62 }
  63
  64 static int ccm_setauthsize(struct crypto_aead *tfm, unsigned int authsize)
  65 {
  66         if ((authsize & 1) || authsize < 4)
  67                 return -EINVAL;
  68         return 0;
  69 }
  70
  71 static int ccm_init_mac(struct aead_request *req, u8 maciv[], u32 msglen)
  72 {
  73         struct crypto_aead *aead = crypto_aead_reqtfm(req);
  74         __be32 *n = (__be32 *)&maciv[AES_BLOCK_SIZE - 8];
  75         u32 l = req->iv[0] + 1;
  76
  77         /* verify that CCM dimension 'L' is set correctly in the IV */
  78         if (l < 2 || l > 8)
  79                 return -EINVAL;
  80
  81         /* verify that msglen can in fact be represented in L bytes */
  82         if (l < 4 && msglen >> (8 * l))
  83                 return -EOVERFLOW;
  84
  85         /*
  86          * Even if the CCM spec allows L values of up to 8, the Linux cryptoapi
  87          * uses a u32 type to represent msglen so the top 4 bytes are always 0.
  88          */
  89         n[0] = 0;
  90         n[1] = cpu_to_be32(msglen);
  91
  92         memcpy(maciv, req->iv, AES_BLOCK_SIZE - l);
  93
  94         /*
  95          * Meaning of byte 0 according to CCM spec (RFC 3610/NIST 800-38C)
  96          * - bits 0..2  : max # of bytes required to represent msglen, minus 1
  97          *                (already set by caller)
  98          * - bits 3..5  : size of auth tag (1 => 4 bytes, 2 => 6 bytes, etc)
  99          * - bit 6      : indicates presence of authenticate-only data
 100          */
 101         maciv[0] |= (crypto_aead_authsize(aead) - 2) << 2;
 102         if (req->assoclen)
 103                 maciv[0] |= 0x40;
 104
 105         memset(&req->iv[AES_BLOCK_SIZE - l], 0, l);
 106         return 0;
 107 }
 108
 109 static void ccm_update_mac(struct crypto_aes_ctx *key, u8 mac[], u8 const in[],
 110                            u32 abytes, u32 *macp, bool use_neon)
 111 {
 112         if (likely(use_neon)) {
 113                 ce_aes_ccm_auth_data(mac, in, abytes, macp, key->key_enc,
 114                                      num_rounds(key));
 115         } else {
 116                 if (*macp > 0 && *macp < AES_BLOCK_SIZE) {
 117                         int added = min(abytes, AES_BLOCK_SIZE - *macp);
 118
 119                         crypto_xor(&mac[*macp], in, added);
 120
 121                         *macp += added;
 122                         in += added;
 123                         abytes -= added;
 124                 }
 125
 126                 while (abytes > AES_BLOCK_SIZE) {
 127                         __aes_arm64_encrypt(key->key_enc, mac, mac,
 128                                             num_rounds(key));
 129                         crypto_xor(mac, in, AES_BLOCK_SIZE);
 130
 131                         in += AES_BLOCK_SIZE;
 132                         abytes -= AES_BLOCK_SIZE;
 133                 }
 134
 135                 if (abytes > 0) {
 136                         __aes_arm64_encrypt(key->key_enc, mac, mac,
 137                                             num_rounds(key));
 138                         crypto_xor(mac, in, abytes);
 139                         *macp = abytes;
 140                 } else {
 141                         *macp = 0;
 142                 }
 143         }
 144 }
 145
 146 static void ccm_calculate_auth_mac(struct aead_request *req, u8 mac[],
 147                                    bool use_neon)
 148 {
 149         struct crypto_aead *aead = crypto_aead_reqtfm(req);
 150         struct crypto_aes_ctx *ctx = crypto_aead_ctx(aead);
 151         struct __packed { __be16 l; __be32 h; u16 len; } ltag;
 152         struct scatter_walk walk;
 153         u32 len = req->assoclen;
 154         u32 macp = 0;
 155
 156         /* prepend the AAD with a length tag */
 157         if (len < 0xff00) {
 158                 ltag.l = cpu_to_be16(len);
 159                 ltag.len = 2;
 160         } else  {
 161                 ltag.l = cpu_to_be16(0xfffe);
 162                 put_unaligned_be32(len, &ltag.h);
 163                 ltag.len = 6;
 164         }
 165
 166         ccm_update_mac(ctx, mac, (u8 *)&ltag, ltag.len, &macp, use_neon);
 167         scatterwalk_start(&walk, req->src);
 168
 169         do {
 170                 u32 n = scatterwalk_clamp(&walk, len);
 171                 u8 *p;
 172
 173                 if (!n) {
 174                         scatterwalk_start(&walk, sg_next(walk.sg));
 175                         n = scatterwalk_clamp(&walk, len);
 176                 }
 177                 p = scatterwalk_map(&walk);
 178                 ccm_update_mac(ctx, mac, p, n, &macp, use_neon);
 179                 len -= n;
 180
 181                 scatterwalk_unmap(p);
 182                 scatterwalk_advance(&walk, n);
 183                 scatterwalk_done(&walk, 0, len);
 184         } while (len);
 185 }
 186
 187 static int ccm_crypt_fallback(struct skcipher_walk *walk, u8 mac[], u8 iv0[],
 188                               struct crypto_aes_ctx *ctx, bool enc)
 189 {
 190         u8 buf[AES_BLOCK_SIZE];
 191         int err = 0;
 192
 193         while (walk->nbytes) {
 194                 int blocks = walk->nbytes / AES_BLOCK_SIZE;
 195                 u32 tail = walk->nbytes % AES_BLOCK_SIZE;
 196                 u8 *dst = walk->dst.virt.addr;
 197                 u8 *src = walk->src.virt.addr;
 198                 u32 nbytes = walk->nbytes;
 199
 200                 if (nbytes == walk->total && tail > 0) {
 201                         blocks++;
 202                         tail = 0;
 203                 }
 204
 205                 do {
 206                         u32 bsize = AES_BLOCK_SIZE;
 207
 208                         if (nbytes < AES_BLOCK_SIZE)
 209                                 bsize = nbytes;
 210
 211                         crypto_inc(walk->iv, AES_BLOCK_SIZE);
 212                         __aes_arm64_encrypt(ctx->key_enc, buf, walk->iv,
 213                                             num_rounds(ctx));
 214                         __aes_arm64_encrypt(ctx->key_enc, mac, mac,
 215                                             num_rounds(ctx));
 216                         if (enc)
 217                                 crypto_xor(mac, src, bsize);
 218                         crypto_xor_cpy(dst, src, buf, bsize);
 219                         if (!enc)
 220                                 crypto_xor(mac, dst, bsize);
 221                         dst += bsize;
 222                         src += bsize;
 223                         nbytes -= bsize;
 224                 } while (--blocks);
 225
 226                 err = skcipher_walk_done(walk, tail);
 227         }
 228
 229         if (!err) {
 230                 __aes_arm64_encrypt(ctx->key_enc, buf, iv0, num_rounds(ctx));
 231                 __aes_arm64_encrypt(ctx->key_enc, mac, mac, num_rounds(ctx));
 232                 crypto_xor(mac, buf, AES_BLOCK_SIZE);
 233         }
 234         return err;
 235 }
 236
 237 static int ccm_encrypt(struct aead_request *req)
 238 {
 239         struct crypto_aead *aead = crypto_aead_reqtfm(req);
 240         struct crypto_aes_ctx *ctx = crypto_aead_ctx(aead);
 241         struct skcipher_walk walk;
 242         u8 __aligned(8) mac[AES_BLOCK_SIZE];
 243         u8 buf[AES_BLOCK_SIZE];
 244         u32 len = req->cryptlen;
 245         bool use_neon = may_use_simd();
 246         int err;
 247
 248         err = ccm_init_mac(req, mac, len);
 249         if (err)
 250                 return err;
 251
 252         if (likely(use_neon))
 253                 kernel_neon_begin();
 254
 255         if (req->assoclen)
 256                 ccm_calculate_auth_mac(req, mac, use_neon);
 257
 258         /* preserve the original iv for the final round */
 259         memcpy(buf, req->iv, AES_BLOCK_SIZE);
 260
 261         err = skcipher_walk_aead_encrypt(&walk, req, true);
 262
 263         if (likely(use_neon)) {
 264                 while (walk.nbytes) {
 265                         u32 tail = walk.nbytes % AES_BLOCK_SIZE;
 266
 267                         if (walk.nbytes == walk.total)
 268                                 tail = 0;
 269
 270                         ce_aes_ccm_encrypt(walk.dst.virt.addr,
 271                                            walk.src.virt.addr,
 272                                            walk.nbytes - tail, ctx->key_enc,
 273                                            num_rounds(ctx), mac, walk.iv);
 274
 275                         err = skcipher_walk_done(&walk, tail);
 276                 }
 277                 if (!err)
 278                         ce_aes_ccm_final(mac, buf, ctx->key_enc,
 279                                          num_rounds(ctx));
 280
 281                 kernel_neon_end();
 282         } else {
 283                 err = ccm_crypt_fallback(&walk, mac, buf, ctx, true);
 284         }
 285         if (err)
 286                 return err;
 287
 288         /* copy authtag to end of dst */
 289         scatterwalk_map_and_copy(mac, req->dst, req->assoclen + req->cryptlen,
 290                                  crypto_aead_authsize(aead), 1);
 291
 292         return 0;
 293 }
 294
 295 static int ccm_decrypt(struct aead_request *req)
 296 {
 297         struct crypto_aead *aead = crypto_aead_reqtfm(req);
 298         struct crypto_aes_ctx *ctx = crypto_aead_ctx(aead);
 299         unsigned int authsize = crypto_aead_authsize(aead);
 300         struct skcipher_walk walk;
 301         u8 __aligned(8) mac[AES_BLOCK_SIZE];
 302         u8 buf[AES_BLOCK_SIZE];
 303         u32 len = req->cryptlen - authsize;
 304         bool use_neon = may_use_simd();
 305         int err;
 306
 307         err = ccm_init_mac(req, mac, len);
 308         if (err)
 309                 return err;
 310
 311         if (likely(use_neon))
 312                 kernel_neon_begin();
 313
 314         if (req->assoclen)
 315                 ccm_calculate_auth_mac(req, mac, use_neon);
 316
 317         /* preserve the original iv for the final round */
 318         memcpy(buf, req->iv, AES_BLOCK_SIZE);
 319
 320         err = skcipher_walk_aead_decrypt(&walk, req, true);
 321
 322         if (likely(use_neon)) {
 323                 while (walk.nbytes) {
 324                         u32 tail = walk.nbytes % AES_BLOCK_SIZE;
 325
 326                         if (walk.nbytes == walk.total)
 327                                 tail = 0;
 328
 329                         ce_aes_ccm_decrypt(walk.dst.virt.addr,
 330                                            walk.src.virt.addr,
 331                                            walk.nbytes - tail, ctx->key_enc,
 332                                            num_rounds(ctx), mac, walk.iv);
 333
 334                         err = skcipher_walk_done(&walk, tail);
 335                 }
 336                 if (!err)
 337                         ce_aes_ccm_final(mac, buf, ctx->key_enc,
 338                                          num_rounds(ctx));
 339
 340                 kernel_neon_end();
 341         } else {
 342                 err = ccm_crypt_fallback(&walk, mac, buf, ctx, false);
 343         }
 344
 345         if (err)
 346                 return err;
 347
 348         /* compare calculated auth tag with the stored one */
 349         scatterwalk_map_and_copy(buf, req->src,
 350                                  req->assoclen + req->cryptlen - authsize,
 351                                  authsize, 0);
 352
 353         if (crypto_memneq(mac, buf, authsize))
 354                 return -EBADMSG;
 355         return 0;
 356 }
 357
 358 static struct aead_alg ccm_aes_alg = {
 359         .base = {
 360                 .cra_name               = "ccm(aes)",
 361                 .cra_driver_name        = "ccm-aes-ce",
 362                 .cra_priority           = 300,
 363                 .cra_blocksize          = 1,
 364                 .cra_ctxsize            = sizeof(struct crypto_aes_ctx),
 365                 .cra_module             = THIS_MODULE,
 366         },
 367         .ivsize         = AES_BLOCK_SIZE,
 368         .chunksize      = AES_BLOCK_SIZE,
 369         .maxauthsize    = AES_BLOCK_SIZE,
 370         .setkey         = ccm_setkey,
 371         .setauthsize    = ccm_setauthsize,
 372         .encrypt        = ccm_encrypt,
 373         .decrypt        = ccm_decrypt,
 374 };
 375
 376 static int __init aes_mod_init(void)
 377 {
 378         if (!(elf_hwcap & HWCAP_AES))
 379                 return -ENODEV;
 380         return crypto_register_aead(&ccm_aes_alg);
 381 }
 382
 383 static void __exit aes_mod_exit(void)
 384 {
 385         crypto_unregister_aead(&ccm_aes_alg);
 386 }
 387
 388 module_init(aes_mod_init);
 389 module_exit(aes_mod_exit);
 390
 391 MODULE_DESCRIPTION("Synchronous AES in CCM mode using ARMv8 Crypto Extensions");
 392 MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");
 393 MODULE_LICENSE("GPL v2");
 394 MODULE_ALIAS_CRYPTO("ccm(aes)");