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