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)
 111 {
 112         if (may_use_simd()) {
 113                 kernel_neon_begin();
 114                 ce_aes_ccm_auth_data(mac, in, abytes, macp, key->key_enc,
 115                                      num_rounds(key));
 116                 kernel_neon_end();
 117         } else {
 118                 if (*macp > 0 && *macp < AES_BLOCK_SIZE) {
 119                         int added = min(abytes, AES_BLOCK_SIZE - *macp);
 120
 121                         crypto_xor(&mac[*macp], in, added);
 122
 123                         *macp += added;
 124                         in += added;
 125                         abytes -= added;
 126                 }
 127
 128                 while (abytes > AES_BLOCK_SIZE) {
 129                         __aes_arm64_encrypt(key->key_enc, mac, mac,
 130                                             num_rounds(key));
 131                         crypto_xor(mac, in, AES_BLOCK_SIZE);
 132
 133                         in += AES_BLOCK_SIZE;
 134                         abytes -= AES_BLOCK_SIZE;
 135                 }
 136
 137                 if (abytes > 0) {
 138                         __aes_arm64_encrypt(key->key_enc, mac, mac,
 139                                             num_rounds(key));
 140                         crypto_xor(mac, in, abytes);
 141                         *macp = abytes;
 142                 } else {
 143                         *macp = 0;
 144                 }
 145         }
 146 }
 147
 148 static void ccm_calculate_auth_mac(struct aead_request *req, u8 mac[])
 149 {
 150         struct crypto_aead *aead = crypto_aead_reqtfm(req);
 151         struct crypto_aes_ctx *ctx = crypto_aead_ctx(aead);
 152         struct __packed { __be16 l; __be32 h; u16 len; } ltag;
 153         struct scatter_walk walk;
 154         u32 len = req->assoclen;
 155         u32 macp = 0;
 156
 157         /* prepend the AAD with a length tag */
 158         if (len < 0xff00) {
 159                 ltag.l = cpu_to_be16(len);
 160                 ltag.len = 2;
 161         } else  {
 162                 ltag.l = cpu_to_be16(0xfffe);
 163                 put_unaligned_be32(len, &ltag.h);
 164                 ltag.len = 6;
 165         }
 166
 167         ccm_update_mac(ctx, mac, (u8 *)&ltag, ltag.len, &macp);
 168         scatterwalk_start(&walk, req->src);
 169
 170         do {
 171                 u32 n = scatterwalk_clamp(&walk, len);
 172                 u8 *p;
 173
 174                 if (!n) {
 175                         scatterwalk_start(&walk, sg_next(walk.sg));
 176                         n = scatterwalk_clamp(&walk, len);
 177                 }
 178                 p = scatterwalk_map(&walk);
 179                 ccm_update_mac(ctx, mac, p, n, &macp);
 180                 len -= n;
 181
 182                 scatterwalk_unmap(p);
 183                 scatterwalk_advance(&walk, n);
 184                 scatterwalk_done(&walk, 0, len);
 185         } while (len);
 186 }
 187
 188 static int ccm_crypt_fallback(struct skcipher_walk *walk, u8 mac[], u8 iv0[],
 189                               struct crypto_aes_ctx *ctx, bool enc)
 190 {
 191         u8 buf[AES_BLOCK_SIZE];
 192         int err = 0;
 193
 194         while (walk->nbytes) {
 195                 int blocks = walk->nbytes / AES_BLOCK_SIZE;
 196                 u32 tail = walk->nbytes % AES_BLOCK_SIZE;
 197                 u8 *dst = walk->dst.virt.addr;
 198                 u8 *src = walk->src.virt.addr;
 199                 u32 nbytes = walk->nbytes;
 200
 201                 if (nbytes == walk->total && tail > 0) {
 202                         blocks++;
 203                         tail = 0;
 204                 }
 205
 206                 do {
 207                         u32 bsize = AES_BLOCK_SIZE;
 208
 209                         if (nbytes < AES_BLOCK_SIZE)
 210                                 bsize = nbytes;
 211
 212                         crypto_inc(walk->iv, AES_BLOCK_SIZE);
 213                         __aes_arm64_encrypt(ctx->key_enc, buf, walk->iv,
 214                                             num_rounds(ctx));
 215                         __aes_arm64_encrypt(ctx->key_enc, mac, mac,
 216                                             num_rounds(ctx));
 217                         if (enc)
 218                                 crypto_xor(mac, src, bsize);
 219                         crypto_xor_cpy(dst, src, buf, bsize);
 220                         if (!enc)
 221                                 crypto_xor(mac, dst, bsize);
 222                         dst += bsize;
 223                         src += bsize;
 224                         nbytes -= bsize;
 225                 } while (--blocks);
 226
 227                 err = skcipher_walk_done(walk, tail);
 228         }
 229
 230         if (!err) {
 231                 __aes_arm64_encrypt(ctx->key_enc, buf, iv0, num_rounds(ctx));
 232                 __aes_arm64_encrypt(ctx->key_enc, mac, mac, num_rounds(ctx));
 233                 crypto_xor(mac, buf, AES_BLOCK_SIZE);
 234         }
 235         return err;
 236 }
 237
 238 static int ccm_encrypt(struct aead_request *req)
 239 {
 240         struct crypto_aead *aead = crypto_aead_reqtfm(req);
 241         struct crypto_aes_ctx *ctx = crypto_aead_ctx(aead);
 242         struct skcipher_walk walk;
 243         u8 __aligned(8) mac[AES_BLOCK_SIZE];
 244         u8 buf[AES_BLOCK_SIZE];
 245         u32 len = req->cryptlen;
 246         int err;
 247
 248         err = ccm_init_mac(req, mac, len);
 249         if (err)
 250                 return err;
 251
 252         if (req->assoclen)
 253                 ccm_calculate_auth_mac(req, mac);
 254
 255         /* preserve the original iv for the final round */
 256         memcpy(buf, req->iv, AES_BLOCK_SIZE);
 257
 258         err = skcipher_walk_aead_encrypt(&walk, req, true);
 259
 260         if (may_use_simd()) {
 261                 while (walk.nbytes) {
 262                         u32 tail = walk.nbytes % AES_BLOCK_SIZE;
 263
 264                         if (walk.nbytes == walk.total)
 265                                 tail = 0;
 266
 267                         kernel_neon_begin();
 268                         ce_aes_ccm_encrypt(walk.dst.virt.addr,
 269                                            walk.src.virt.addr,
 270                                            walk.nbytes - tail, ctx->key_enc,
 271                                            num_rounds(ctx), mac, walk.iv);
 272                         kernel_neon_end();
 273
 274                         err = skcipher_walk_done(&walk, tail);
 275                 }
 276                 if (!err) {
 277                         kernel_neon_begin();
 278                         ce_aes_ccm_final(mac, buf, ctx->key_enc,
 279                                          num_rounds(ctx));
 280                         kernel_neon_end();
 281                 }
 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         int err;
 305
 306         err = ccm_init_mac(req, mac, len);
 307         if (err)
 308                 return err;
 309
 310         if (req->assoclen)
 311                 ccm_calculate_auth_mac(req, mac);
 312
 313         /* preserve the original iv for the final round */
 314         memcpy(buf, req->iv, AES_BLOCK_SIZE);
 315
 316         err = skcipher_walk_aead_decrypt(&walk, req, true);
 317
 318         if (may_use_simd()) {
 319                 while (walk.nbytes) {
 320                         u32 tail = walk.nbytes % AES_BLOCK_SIZE;
 321
 322                         if (walk.nbytes == walk.total)
 323                                 tail = 0;
 324
 325                         kernel_neon_begin();
 326                         ce_aes_ccm_decrypt(walk.dst.virt.addr,
 327                                            walk.src.virt.addr,
 328                                            walk.nbytes - tail, ctx->key_enc,
 329                                            num_rounds(ctx), mac, walk.iv);
 330                         kernel_neon_end();
 331
 332                         err = skcipher_walk_done(&walk, tail);
 333                 }
 334                 if (!err) {
 335                         kernel_neon_begin();
 336                         ce_aes_ccm_final(mac, buf, ctx->key_enc,
 337                                          num_rounds(ctx));
 338                         kernel_neon_end();
 339                 }
 340         } else {
 341                 err = ccm_crypt_fallback(&walk, mac, buf, ctx, false);
 342         }
 343
 344         if (err)
 345                 return err;
 346
 347         /* compare calculated auth tag with the stored one */
 348         scatterwalk_map_and_copy(buf, req->src,
 349                                  req->assoclen + req->cryptlen - authsize,
 350                                  authsize, 0);
 351
 352         if (crypto_memneq(mac, buf, authsize))
 353                 return -EBADMSG;
 354         return 0;
 355 }
 356
 357 static struct aead_alg ccm_aes_alg = {
 358         .base = {
 359                 .cra_name               = "ccm(aes)",
 360                 .cra_driver_name        = "ccm-aes-ce",
 361                 .cra_priority           = 300,
 362                 .cra_blocksize          = 1,
 363                 .cra_ctxsize            = sizeof(struct crypto_aes_ctx),
 364                 .cra_module             = THIS_MODULE,
 365         },
 366         .ivsize         = AES_BLOCK_SIZE,
 367         .chunksize      = AES_BLOCK_SIZE,
 368         .maxauthsize    = AES_BLOCK_SIZE,
 369         .setkey         = ccm_setkey,
 370         .setauthsize    = ccm_setauthsize,
 371         .encrypt        = ccm_encrypt,
 372         .decrypt        = ccm_decrypt,
 373 };
 374
 375 static int __init aes_mod_init(void)
 376 {
 377         if (!(elf_hwcap & HWCAP_AES))
 378                 return -ENODEV;
 379         return crypto_register_aead(&ccm_aes_alg);
 380 }
 381
 382 static void __exit aes_mod_exit(void)
 383 {
 384         crypto_unregister_aead(&ccm_aes_alg);
 385 }
 386
 387 module_init(aes_mod_init);
 388 module_exit(aes_mod_exit);
 389
 390 MODULE_DESCRIPTION("Synchronous AES in CCM mode using ARMv8 Crypto Extensions");
 391 MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");
 392 MODULE_LICENSE("GPL v2");
 393 MODULE_ALIAS_CRYPTO("ccm(aes)");