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

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * aes-ccm-glue.c - AES-CCM transform for ARMv8 with Crypto Extensions
   4  *
   5  * Copyright (C) 2013 - 2017 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/scatterwalk.h>
  13 #include <crypto/internal/aead.h>
  14 #include <crypto/internal/simd.h>
  15 #include <crypto/internal/skcipher.h>
  16 #include <linux/module.h>
  17
  18 #include "aes-ce-setkey.h"
  19
  20 static int num_rounds(struct crypto_aes_ctx *ctx)
  21 {
  22         /*
  23          * # of rounds specified by AES:
  24          * 128 bit key          10 rounds
  25          * 192 bit key          12 rounds
  26          * 256 bit key          14 rounds
  27          * => n byte key        => 6 + (n/4) rounds
  28          */
  29         return 6 + ctx->key_length / 4;
  30 }
  31
  32 asmlinkage void ce_aes_ccm_auth_data(u8 mac[], u8 const in[], u32 abytes,
  33                                      u32 *macp, u32 const rk[], u32 rounds);
  34
  35 asmlinkage void ce_aes_ccm_encrypt(u8 out[], u8 const in[], u32 cbytes,
  36                                    u32 const rk[], u32 rounds, u8 mac[],
  37                                    u8 ctr[]);
  38
  39 asmlinkage void ce_aes_ccm_decrypt(u8 out[], u8 const in[], u32 cbytes,
  40                                    u32 const rk[], u32 rounds, u8 mac[],
  41                                    u8 ctr[]);
  42
  43 asmlinkage void ce_aes_ccm_final(u8 mac[], u8 const ctr[], u32 const rk[],
  44                                  u32 rounds);
  45
  46 asmlinkage void __aes_arm64_encrypt(u32 *rk, u8 *out, const u8 *in, int rounds);
  47
  48 static int ccm_setkey(struct crypto_aead *tfm, const u8 *in_key,
  49                       unsigned int key_len)
  50 {
  51         struct crypto_aes_ctx *ctx = crypto_aead_ctx(tfm);
  52         int ret;
  53
  54         ret = ce_aes_expandkey(ctx, in_key, key_len);
  55         if (!ret)
  56                 return 0;
  57
  58         tfm->base.crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
  59         return -EINVAL;
  60 }
  61
  62 static int ccm_setauthsize(struct crypto_aead *tfm, unsigned int authsize)
  63 {
  64         if ((authsize & 1) || authsize < 4)
  65                 return -EINVAL;
  66         return 0;
  67 }
  68
  69 static int ccm_init_mac(struct aead_request *req, u8 maciv[], u32 msglen)
  70 {
  71         struct crypto_aead *aead = crypto_aead_reqtfm(req);
  72         __be32 *n = (__be32 *)&maciv[AES_BLOCK_SIZE - 8];
  73         u32 l = req->iv[0] + 1;
  74
  75         /* verify that CCM dimension 'L' is set correctly in the IV */
  76         if (l < 2 || l > 8)
  77                 return -EINVAL;
  78
  79         /* verify that msglen can in fact be represented in L bytes */
  80         if (l < 4 && msglen >> (8 * l))
  81                 return -EOVERFLOW;
  82
  83         /*
  84          * Even if the CCM spec allows L values of up to 8, the Linux cryptoapi
  85          * uses a u32 type to represent msglen so the top 4 bytes are always 0.
  86          */
  87         n[0] = 0;
  88         n[1] = cpu_to_be32(msglen);
  89
  90         memcpy(maciv, req->iv, AES_BLOCK_SIZE - l);
  91
  92         /*
  93          * Meaning of byte 0 according to CCM spec (RFC 3610/NIST 800-38C)
  94          * - bits 0..2  : max # of bytes required to represent msglen, minus 1
  95          *                (already set by caller)
  96          * - bits 3..5  : size of auth tag (1 => 4 bytes, 2 => 6 bytes, etc)
  97          * - bit 6      : indicates presence of authenticate-only data
  98          */
  99         maciv[0] |= (crypto_aead_authsize(aead) - 2) << 2;
 100         if (req->assoclen)
 101                 maciv[0] |= 0x40;
 102
 103         memset(&req->iv[AES_BLOCK_SIZE - l], 0, l);
 104         return 0;
 105 }
 106
 107 static void ccm_update_mac(struct crypto_aes_ctx *key, u8 mac[], u8 const in[],
 108                            u32 abytes, u32 *macp)
 109 {
 110         if (crypto_simd_usable()) {
 111                 kernel_neon_begin();
 112                 ce_aes_ccm_auth_data(mac, in, abytes, macp, key->key_enc,
 113                                      num_rounds(key));
 114                 kernel_neon_end();
 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                 }
 141         }
 142 }
 143
 144 static void ccm_calculate_auth_mac(struct aead_request *req, u8 mac[])
 145 {
 146         struct crypto_aead *aead = crypto_aead_reqtfm(req);
 147         struct crypto_aes_ctx *ctx = crypto_aead_ctx(aead);
 148         struct __packed { __be16 l; __be32 h; u16 len; } ltag;
 149         struct scatter_walk walk;
 150         u32 len = req->assoclen;
 151         u32 macp = 0;
 152
 153         /* prepend the AAD with a length tag */
 154         if (len < 0xff00) {
 155                 ltag.l = cpu_to_be16(len);
 156                 ltag.len = 2;
 157         } else  {
 158                 ltag.l = cpu_to_be16(0xfffe);
 159                 put_unaligned_be32(len, &ltag.h);
 160                 ltag.len = 6;
 161         }
 162
 163         ccm_update_mac(ctx, mac, (u8 *)&ltag, ltag.len, &macp);
 164         scatterwalk_start(&walk, req->src);
 165
 166         do {
 167                 u32 n = scatterwalk_clamp(&walk, len);
 168                 u8 *p;
 169
 170                 if (!n) {
 171                         scatterwalk_start(&walk, sg_next(walk.sg));
 172                         n = scatterwalk_clamp(&walk, len);
 173                 }
 174                 p = scatterwalk_map(&walk);
 175                 ccm_update_mac(ctx, mac, p, n, &macp);
 176                 len -= n;
 177
 178                 scatterwalk_unmap(p);
 179                 scatterwalk_advance(&walk, n);
 180                 scatterwalk_done(&walk, 0, len);
 181         } while (len);
 182 }
 183
 184 static int ccm_crypt_fallback(struct skcipher_walk *walk, u8 mac[], u8 iv0[],
 185                               struct crypto_aes_ctx *ctx, bool enc)
 186 {
 187         u8 buf[AES_BLOCK_SIZE];
 188         int err = 0;
 189
 190         while (walk->nbytes) {
 191                 int blocks = walk->nbytes / AES_BLOCK_SIZE;
 192                 u32 tail = walk->nbytes % AES_BLOCK_SIZE;
 193                 u8 *dst = walk->dst.virt.addr;
 194                 u8 *src = walk->src.virt.addr;
 195                 u32 nbytes = walk->nbytes;
 196
 197                 if (nbytes == walk->total && tail > 0) {
 198                         blocks++;
 199                         tail = 0;
 200                 }
 201
 202                 do {
 203                         u32 bsize = AES_BLOCK_SIZE;
 204
 205                         if (nbytes < AES_BLOCK_SIZE)
 206                                 bsize = nbytes;
 207
 208                         crypto_inc(walk->iv, AES_BLOCK_SIZE);
 209                         __aes_arm64_encrypt(ctx->key_enc, buf, walk->iv,
 210                                             num_rounds(ctx));
 211                         __aes_arm64_encrypt(ctx->key_enc, mac, mac,
 212                                             num_rounds(ctx));
 213                         if (enc)
 214                                 crypto_xor(mac, src, bsize);
 215                         crypto_xor_cpy(dst, src, buf, bsize);
 216                         if (!enc)
 217                                 crypto_xor(mac, dst, bsize);
 218                         dst += bsize;
 219                         src += bsize;
 220                         nbytes -= bsize;
 221                 } while (--blocks);
 222
 223                 err = skcipher_walk_done(walk, tail);
 224         }
 225
 226         if (!err) {
 227                 __aes_arm64_encrypt(ctx->key_enc, buf, iv0, num_rounds(ctx));
 228                 __aes_arm64_encrypt(ctx->key_enc, mac, mac, num_rounds(ctx));
 229                 crypto_xor(mac, buf, AES_BLOCK_SIZE);
 230         }
 231         return err;
 232 }
 233
 234 static int ccm_encrypt(struct aead_request *req)
 235 {
 236         struct crypto_aead *aead = crypto_aead_reqtfm(req);
 237         struct crypto_aes_ctx *ctx = crypto_aead_ctx(aead);
 238         struct skcipher_walk walk;
 239         u8 __aligned(8) mac[AES_BLOCK_SIZE];
 240         u8 buf[AES_BLOCK_SIZE];
 241         u32 len = req->cryptlen;
 242         int err;
 243
 244         err = ccm_init_mac(req, mac, len);
 245         if (err)
 246                 return err;
 247
 248         if (req->assoclen)
 249                 ccm_calculate_auth_mac(req, mac);
 250
 251         /* preserve the original iv for the final round */
 252         memcpy(buf, req->iv, AES_BLOCK_SIZE);
 253
 254         err = skcipher_walk_aead_encrypt(&walk, req, false);
 255
 256         if (crypto_simd_usable()) {
 257                 while (walk.nbytes) {
 258                         u32 tail = walk.nbytes % AES_BLOCK_SIZE;
 259
 260                         if (walk.nbytes == walk.total)
 261                                 tail = 0;
 262
 263                         kernel_neon_begin();
 264                         ce_aes_ccm_encrypt(walk.dst.virt.addr,
 265                                            walk.src.virt.addr,
 266                                            walk.nbytes - tail, ctx->key_enc,
 267                                            num_rounds(ctx), mac, walk.iv);
 268                         kernel_neon_end();
 269
 270                         err = skcipher_walk_done(&walk, tail);
 271                 }
 272                 if (!err) {
 273                         kernel_neon_begin();
 274                         ce_aes_ccm_final(mac, buf, ctx->key_enc,
 275                                          num_rounds(ctx));
 276                         kernel_neon_end();
 277                 }
 278         } else {
 279                 err = ccm_crypt_fallback(&walk, mac, buf, ctx, true);
 280         }
 281         if (err)
 282                 return err;
 283
 284         /* copy authtag to end of dst */
 285         scatterwalk_map_and_copy(mac, req->dst, req->assoclen + req->cryptlen,
 286                                  crypto_aead_authsize(aead), 1);
 287
 288         return 0;
 289 }
 290
 291 static int ccm_decrypt(struct aead_request *req)
 292 {
 293         struct crypto_aead *aead = crypto_aead_reqtfm(req);
 294         struct crypto_aes_ctx *ctx = crypto_aead_ctx(aead);
 295         unsigned int authsize = crypto_aead_authsize(aead);
 296         struct skcipher_walk walk;
 297         u8 __aligned(8) mac[AES_BLOCK_SIZE];
 298         u8 buf[AES_BLOCK_SIZE];
 299         u32 len = req->cryptlen - authsize;
 300         int err;
 301
 302         err = ccm_init_mac(req, mac, len);
 303         if (err)
 304                 return err;
 305
 306         if (req->assoclen)
 307                 ccm_calculate_auth_mac(req, mac);
 308
 309         /* preserve the original iv for the final round */
 310         memcpy(buf, req->iv, AES_BLOCK_SIZE);
 311
 312         err = skcipher_walk_aead_decrypt(&walk, req, false);
 313
 314         if (crypto_simd_usable()) {
 315                 while (walk.nbytes) {
 316                         u32 tail = walk.nbytes % AES_BLOCK_SIZE;
 317
 318                         if (walk.nbytes == walk.total)
 319                                 tail = 0;
 320
 321                         kernel_neon_begin();
 322                         ce_aes_ccm_decrypt(walk.dst.virt.addr,
 323                                            walk.src.virt.addr,
 324                                            walk.nbytes - tail, ctx->key_enc,
 325                                            num_rounds(ctx), mac, walk.iv);
 326                         kernel_neon_end();
 327
 328                         err = skcipher_walk_done(&walk, tail);
 329                 }
 330                 if (!err) {
 331                         kernel_neon_begin();
 332                         ce_aes_ccm_final(mac, buf, ctx->key_enc,
 333                                          num_rounds(ctx));
 334                         kernel_neon_end();
 335                 }
 336         } else {
 337                 err = ccm_crypt_fallback(&walk, mac, buf, ctx, false);
 338         }
 339
 340         if (err)
 341                 return err;
 342
 343         /* compare calculated auth tag with the stored one */
 344         scatterwalk_map_and_copy(buf, req->src,
 345                                  req->assoclen + req->cryptlen - authsize,
 346                                  authsize, 0);
 347
 348         if (crypto_memneq(mac, buf, authsize))
 349                 return -EBADMSG;
 350         return 0;
 351 }
 352
 353 static struct aead_alg ccm_aes_alg = {
 354         .base = {
 355                 .cra_name               = "ccm(aes)",
 356                 .cra_driver_name        = "ccm-aes-ce",
 357                 .cra_priority           = 300,
 358                 .cra_blocksize          = 1,
 359                 .cra_ctxsize            = sizeof(struct crypto_aes_ctx),
 360                 .cra_module             = THIS_MODULE,
 361         },
 362         .ivsize         = AES_BLOCK_SIZE,
 363         .chunksize      = AES_BLOCK_SIZE,
 364         .maxauthsize    = AES_BLOCK_SIZE,
 365         .setkey         = ccm_setkey,
 366         .setauthsize    = ccm_setauthsize,
 367         .encrypt        = ccm_encrypt,
 368         .decrypt        = ccm_decrypt,
 369 };
 370
 371 static int __init aes_mod_init(void)
 372 {
 373         if (!cpu_have_named_feature(AES))
 374                 return -ENODEV;
 375         return crypto_register_aead(&ccm_aes_alg);
 376 }
 377
 378 static void __exit aes_mod_exit(void)
 379 {
 380         crypto_unregister_aead(&ccm_aes_alg);
 381 }
 382
 383 module_init(aes_mod_init);
 384 module_exit(aes_mod_exit);
 385
 386 MODULE_DESCRIPTION("Synchronous AES in CCM mode using ARMv8 Crypto Extensions");
 387 MODULE_AUTHOR("Ard Biesheuvel <ard.biesheuvel@linaro.org>");
 388 MODULE_LICENSE("GPL v2");
 389 MODULE_ALIAS_CRYPTO("ccm(aes)");