drivers/crypto/padlock-aes.c

   1 /*
   2  * Cryptographic API.
   3  *
   4  * Support for VIA PadLock hardware crypto engine.
   5  *
   6  * Copyright (c) 2004  Michal Ludvig <michal@logix.cz>
   7  *
   8  * Key expansion routine taken from crypto/aes.c
   9  *
  10  * This program is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU General Public License as published by
  12  * the Free Software Foundation; either version 2 of the License, or
  13  * (at your option) any later version.
  14  *
  15  * ---------------------------------------------------------------------------
  16  * Copyright (c) 2002, Dr Brian Gladman <brg@gladman.me.uk>, Worcester, UK.
  17  * All rights reserved.
  18  *
  19  * LICENSE TERMS
  20  *
  21  * The free distribution and use of this software in both source and binary
  22  * form is allowed (with or without changes) provided that:
  23  *
  24  *   1. distributions of this source code include the above copyright
  25  *      notice, this list of conditions and the following disclaimer;
  26  *
  27  *   2. distributions in binary form include the above copyright
  28  *      notice, this list of conditions and the following disclaimer
  29  *      in the documentation and/or other associated materials;
  30  *
  31  *   3. the copyright holder's name is not used to endorse products
  32  *      built using this software without specific written permission.
  33  *
  34  * ALTERNATIVELY, provided that this notice is retained in full, this product
  35  * may be distributed under the terms of the GNU General Public License (GPL),
  36  * in which case the provisions of the GPL apply INSTEAD OF those given above.
  37  *
  38  * DISCLAIMER
  39  *
  40  * This software is provided 'as is' with no explicit or implied warranties
  41  * in respect of its properties, including, but not limited to, correctness
  42  * and/or fitness for purpose.
  43  * ---------------------------------------------------------------------------
  44  */
  45
  46 #include <linux/module.h>
  47 #include <linux/init.h>
  48 #include <linux/types.h>
  49 #include <linux/errno.h>
  50 #include <linux/crypto.h>
  51 #include <linux/interrupt.h>
  52 #include <asm/byteorder.h>
  53 #include "padlock.h"
  54
  55 #define AES_MIN_KEY_SIZE        16      /* in uint8_t units */
  56 #define AES_MAX_KEY_SIZE        32      /* ditto */
  57 #define AES_BLOCK_SIZE          16      /* ditto */
  58 #define AES_EXTENDED_KEY_SIZE   64      /* in uint32_t units */
  59 #define AES_EXTENDED_KEY_SIZE_B (AES_EXTENDED_KEY_SIZE * sizeof(uint32_t))
  60
  61 struct aes_ctx {
  62         uint32_t e_data[AES_EXTENDED_KEY_SIZE+4];
  63         uint32_t d_data[AES_EXTENDED_KEY_SIZE+4];
  64         uint32_t *E;
  65         uint32_t *D;
  66         int key_length;
  67 };
  68
  69 /* ====== Key management routines ====== */
  70
  71 static inline uint32_t
  72 generic_rotr32 (const uint32_t x, const unsigned bits)
  73 {
  74         const unsigned n = bits % 32;
  75         return (x >> n) | (x << (32 - n));
  76 }
  77
  78 static inline uint32_t
  79 generic_rotl32 (const uint32_t x, const unsigned bits)
  80 {
  81         const unsigned n = bits % 32;
  82         return (x << n) | (x >> (32 - n));
  83 }
  84
  85 #define rotl generic_rotl32
  86 #define rotr generic_rotr32
  87
  88 /*
  89  * #define byte(x, nr) ((unsigned char)((x) >> (nr*8)))
  90  */
  91 static inline uint8_t
  92 byte(const uint32_t x, const unsigned n)
  93 {
  94         return x >> (n << 3);
  95 }
  96
  97 #define uint32_t_in(x) le32_to_cpu(*(const uint32_t *)(x))
  98 #define uint32_t_out(to, from) (*(uint32_t *)(to) = cpu_to_le32(from))
  99
 100 #define E_KEY ctx->E
 101 #define D_KEY ctx->D
 102
 103 static uint8_t pow_tab[256];
 104 static uint8_t log_tab[256];
 105 static uint8_t sbx_tab[256];
 106 static uint8_t isb_tab[256];
 107 static uint32_t rco_tab[10];
 108 static uint32_t ft_tab[4][256];
 109 static uint32_t it_tab[4][256];
 110
 111 static uint32_t fl_tab[4][256];
 112 static uint32_t il_tab[4][256];
 113
 114 static inline uint8_t
 115 f_mult (uint8_t a, uint8_t b)
 116 {
 117         uint8_t aa = log_tab[a], cc = aa + log_tab[b];
 118
 119         return pow_tab[cc + (cc < aa ? 1 : 0)];
 120 }
 121
 122 #define ff_mult(a,b)    (a && b ? f_mult(a, b) : 0)
 123
 124 #define f_rn(bo, bi, n, k)                                      \
 125     bo[n] =  ft_tab[0][byte(bi[n],0)] ^                         \
 126              ft_tab[1][byte(bi[(n + 1) & 3],1)] ^               \
 127              ft_tab[2][byte(bi[(n + 2) & 3],2)] ^               \
 128              ft_tab[3][byte(bi[(n + 3) & 3],3)] ^ *(k + n)
 129
 130 #define i_rn(bo, bi, n, k)                                      \
 131     bo[n] =  it_tab[0][byte(bi[n],0)] ^                         \
 132              it_tab[1][byte(bi[(n + 3) & 3],1)] ^               \
 133              it_tab[2][byte(bi[(n + 2) & 3],2)] ^               \
 134              it_tab[3][byte(bi[(n + 1) & 3],3)] ^ *(k + n)
 135
 136 #define ls_box(x)                               \
 137     ( fl_tab[0][byte(x, 0)] ^                   \
 138       fl_tab[1][byte(x, 1)] ^                   \
 139       fl_tab[2][byte(x, 2)] ^                   \
 140       fl_tab[3][byte(x, 3)] )
 141
 142 #define f_rl(bo, bi, n, k)                                      \
 143     bo[n] =  fl_tab[0][byte(bi[n],0)] ^                         \
 144              fl_tab[1][byte(bi[(n + 1) & 3],1)] ^               \
 145              fl_tab[2][byte(bi[(n + 2) & 3],2)] ^               \
 146              fl_tab[3][byte(bi[(n + 3) & 3],3)] ^ *(k + n)
 147
 148 #define i_rl(bo, bi, n, k)                                      \
 149     bo[n] =  il_tab[0][byte(bi[n],0)] ^                         \
 150              il_tab[1][byte(bi[(n + 3) & 3],1)] ^               \
 151              il_tab[2][byte(bi[(n + 2) & 3],2)] ^               \
 152              il_tab[3][byte(bi[(n + 1) & 3],3)] ^ *(k + n)
 153
 154 static void
 155 gen_tabs (void)
 156 {
 157         uint32_t i, t;
 158         uint8_t p, q;
 159
 160         /* log and power tables for GF(2**8) finite field with
 161            0x011b as modular polynomial - the simplest prmitive
 162            root is 0x03, used here to generate the tables */
 163
 164         for (i = 0, p = 1; i < 256; ++i) {
 165                 pow_tab[i] = (uint8_t) p;
 166                 log_tab[p] = (uint8_t) i;
 167
 168                 p ^= (p << 1) ^ (p & 0x80 ? 0x01b : 0);
 169         }
 170
 171         log_tab[1] = 0;
 172
 173         for (i = 0, p = 1; i < 10; ++i) {
 174                 rco_tab[i] = p;
 175
 176                 p = (p << 1) ^ (p & 0x80 ? 0x01b : 0);
 177         }
 178
 179         for (i = 0; i < 256; ++i) {
 180                 p = (i ? pow_tab[255 - log_tab[i]] : 0);
 181                 q = ((p >> 7) | (p << 1)) ^ ((p >> 6) | (p << 2));
 182                 p ^= 0x63 ^ q ^ ((q >> 6) | (q << 2));
 183                 sbx_tab[i] = p;
 184                 isb_tab[p] = (uint8_t) i;
 185         }
 186
 187         for (i = 0; i < 256; ++i) {
 188                 p = sbx_tab[i];
 189
 190                 t = p;
 191                 fl_tab[0][i] = t;
 192                 fl_tab[1][i] = rotl (t, 8);
 193                 fl_tab[2][i] = rotl (t, 16);
 194                 fl_tab[3][i] = rotl (t, 24);
 195
 196                 t = ((uint32_t) ff_mult (2, p)) |
 197                     ((uint32_t) p << 8) |
 198                     ((uint32_t) p << 16) | ((uint32_t) ff_mult (3, p) << 24);
 199
 200                 ft_tab[0][i] = t;
 201                 ft_tab[1][i] = rotl (t, 8);
 202                 ft_tab[2][i] = rotl (t, 16);
 203                 ft_tab[3][i] = rotl (t, 24);
 204
 205                 p = isb_tab[i];
 206
 207                 t = p;
 208                 il_tab[0][i] = t;
 209                 il_tab[1][i] = rotl (t, 8);
 210                 il_tab[2][i] = rotl (t, 16);
 211                 il_tab[3][i] = rotl (t, 24);
 212
 213                 t = ((uint32_t) ff_mult (14, p)) |
 214                     ((uint32_t) ff_mult (9, p) << 8) |
 215                     ((uint32_t) ff_mult (13, p) << 16) |
 216                     ((uint32_t) ff_mult (11, p) << 24);
 217
 218                 it_tab[0][i] = t;
 219                 it_tab[1][i] = rotl (t, 8);
 220                 it_tab[2][i] = rotl (t, 16);
 221                 it_tab[3][i] = rotl (t, 24);
 222         }
 223 }
 224
 225 #define star_x(x) (((x) & 0x7f7f7f7f) << 1) ^ ((((x) & 0x80808080) >> 7) * 0x1b)
 226
 227 #define imix_col(y,x)       \
 228     u   = star_x(x);        \
 229     v   = star_x(u);        \
 230     w   = star_x(v);        \
 231     t   = w ^ (x);          \
 232    (y)  = u ^ v ^ w;        \
 233    (y) ^= rotr(u ^ t,  8) ^ \
 234           rotr(v ^ t, 16) ^ \
 235           rotr(t,24)
 236
 237 /* initialise the key schedule from the user supplied key */
 238
 239 #define loop4(i)                                    \
 240 {   t = rotr(t,  8); t = ls_box(t) ^ rco_tab[i];    \
 241     t ^= E_KEY[4 * i];     E_KEY[4 * i + 4] = t;    \
 242     t ^= E_KEY[4 * i + 1]; E_KEY[4 * i + 5] = t;    \
 243     t ^= E_KEY[4 * i + 2]; E_KEY[4 * i + 6] = t;    \
 244     t ^= E_KEY[4 * i + 3]; E_KEY[4 * i + 7] = t;    \
 245 }
 246
 247 #define loop6(i)                                    \
 248 {   t = rotr(t,  8); t = ls_box(t) ^ rco_tab[i];    \
 249     t ^= E_KEY[6 * i];     E_KEY[6 * i + 6] = t;    \
 250     t ^= E_KEY[6 * i + 1]; E_KEY[6 * i + 7] = t;    \
 251     t ^= E_KEY[6 * i + 2]; E_KEY[6 * i + 8] = t;    \
 252     t ^= E_KEY[6 * i + 3]; E_KEY[6 * i + 9] = t;    \
 253     t ^= E_KEY[6 * i + 4]; E_KEY[6 * i + 10] = t;   \
 254     t ^= E_KEY[6 * i + 5]; E_KEY[6 * i + 11] = t;   \
 255 }
 256
 257 #define loop8(i)                                    \
 258 {   t = rotr(t,  8); ; t = ls_box(t) ^ rco_tab[i];  \
 259     t ^= E_KEY[8 * i];     E_KEY[8 * i + 8] = t;    \
 260     t ^= E_KEY[8 * i + 1]; E_KEY[8 * i + 9] = t;    \
 261     t ^= E_KEY[8 * i + 2]; E_KEY[8 * i + 10] = t;   \
 262     t ^= E_KEY[8 * i + 3]; E_KEY[8 * i + 11] = t;   \
 263     t  = E_KEY[8 * i + 4] ^ ls_box(t);    \
 264     E_KEY[8 * i + 12] = t;                \
 265     t ^= E_KEY[8 * i + 5]; E_KEY[8 * i + 13] = t;   \
 266     t ^= E_KEY[8 * i + 6]; E_KEY[8 * i + 14] = t;   \
 267     t ^= E_KEY[8 * i + 7]; E_KEY[8 * i + 15] = t;   \
 268 }
 269
 270 /* Tells whether the ACE is capable to generate
 271    the extended key for a given key_len. */
 272 static inline int
 273 aes_hw_extkey_available(uint8_t key_len)
 274 {
 275         /* TODO: We should check the actual CPU model/stepping
 276                  as it's possible that the capability will be
 277                  added in the next CPU revisions. */
 278         if (key_len == 16)
 279                 return 1;
 280         return 0;
 281 }
 282
 283 static int
 284 aes_set_key(void *ctx_arg, const uint8_t *in_key, unsigned int key_len, uint32_t *flags)
 285 {
 286         struct aes_ctx *ctx = ctx_arg;
 287         uint32_t i, t, u, v, w;
 288         uint32_t P[AES_EXTENDED_KEY_SIZE];
 289         uint32_t rounds;
 290
 291         if (key_len != 16 && key_len != 24 && key_len != 32) {
 292                 *flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
 293                 return -EINVAL;
 294         }
 295
 296         ctx->key_length = key_len;
 297
 298         ctx->E = ctx->e_data;
 299         ctx->D = ctx->d_data;
 300
 301         /* Ensure 16-Bytes alignmentation of keys for VIA PadLock. */
 302         if ((int)(ctx->e_data) & 0x0F)
 303                 ctx->E += 4 - (((int)(ctx->e_data) & 0x0F) / sizeof (ctx->e_data[0]));
 304
 305         if ((int)(ctx->d_data) & 0x0F)
 306                 ctx->D += 4 - (((int)(ctx->d_data) & 0x0F) / sizeof (ctx->d_data[0]));
 307
 308         E_KEY[0] = uint32_t_in (in_key);
 309         E_KEY[1] = uint32_t_in (in_key + 4);
 310         E_KEY[2] = uint32_t_in (in_key + 8);
 311         E_KEY[3] = uint32_t_in (in_key + 12);
 312
 313         /* Don't generate extended keys if the hardware can do it. */
 314         if (aes_hw_extkey_available(key_len))
 315                 return 0;
 316
 317         switch (key_len) {
 318         case 16:
 319                 t = E_KEY[3];
 320                 for (i = 0; i < 10; ++i)
 321                         loop4 (i);
 322                 break;
 323
 324         case 24:
 325                 E_KEY[4] = uint32_t_in (in_key + 16);
 326                 t = E_KEY[5] = uint32_t_in (in_key + 20);
 327                 for (i = 0; i < 8; ++i)
 328                         loop6 (i);
 329                 break;
 330
 331         case 32:
 332                 E_KEY[4] = uint32_t_in (in_key + 16);
 333                 E_KEY[5] = uint32_t_in (in_key + 20);
 334                 E_KEY[6] = uint32_t_in (in_key + 24);
 335                 t = E_KEY[7] = uint32_t_in (in_key + 28);
 336                 for (i = 0; i < 7; ++i)
 337                         loop8 (i);
 338                 break;
 339         }
 340
 341         D_KEY[0] = E_KEY[0];
 342         D_KEY[1] = E_KEY[1];
 343         D_KEY[2] = E_KEY[2];
 344         D_KEY[3] = E_KEY[3];
 345
 346         for (i = 4; i < key_len + 24; ++i) {
 347                 imix_col (D_KEY[i], E_KEY[i]);
 348         }
 349
 350         /* PadLock needs a different format of the decryption key. */
 351         rounds = 10 + (key_len - 16) / 4;
 352
 353         for (i = 0; i < rounds; i++) {
 354                 P[((i + 1) * 4) + 0] = D_KEY[((rounds - i - 1) * 4) + 0];
 355                 P[((i + 1) * 4) + 1] = D_KEY[((rounds - i - 1) * 4) + 1];
 356                 P[((i + 1) * 4) + 2] = D_KEY[((rounds - i - 1) * 4) + 2];
 357                 P[((i + 1) * 4) + 3] = D_KEY[((rounds - i - 1) * 4) + 3];
 358         }
 359
 360         P[0] = E_KEY[(rounds * 4) + 0];
 361         P[1] = E_KEY[(rounds * 4) + 1];
 362         P[2] = E_KEY[(rounds * 4) + 2];
 363         P[3] = E_KEY[(rounds * 4) + 3];
 364
 365         memcpy(D_KEY, P, AES_EXTENDED_KEY_SIZE_B);
 366
 367         return 0;
 368 }
 369
 370 /* ====== Encryption/decryption routines ====== */
 371
 372 /* This is the real call to PadLock. */
 373 static inline void
 374 padlock_xcrypt_ecb(uint8_t *input, uint8_t *output, uint8_t *key,
 375                    void *control_word, uint32_t count)
 376 {
 377         asm volatile ("pushfl; popfl");         /* enforce key reload. */
 378         asm volatile (".byte 0xf3,0x0f,0xa7,0xc8"       /* rep xcryptecb */
 379                       : "+S"(input), "+D"(output)
 380                       : "d"(control_word), "b"(key), "c"(count));
 381 }
 382
 383 static void
 384 aes_padlock(void *ctx_arg, uint8_t *out_arg, const uint8_t *in_arg, int encdec)
 385 {
 386         /* Don't blindly modify this structure - the items must
 387            fit on 16-Bytes boundaries! */
 388         struct padlock_xcrypt_data {
 389                 uint8_t buf[AES_BLOCK_SIZE];
 390                 union cword cword;
 391         };
 392
 393         struct aes_ctx *ctx = ctx_arg;
 394         char bigbuf[sizeof(struct padlock_xcrypt_data) + 16];
 395         struct padlock_xcrypt_data *data;
 396         void *key;
 397
 398         /* Place 'data' at the first 16-Bytes aligned address in 'bigbuf'. */
 399         if (((long)bigbuf) & 0x0F)
 400                 data = (void*)(bigbuf + 16 - ((long)bigbuf & 0x0F));
 401         else
 402                 data = (void*)bigbuf;
 403
 404         /* Prepare Control word. */
 405         memset (data, 0, sizeof(struct padlock_xcrypt_data));
 406         data->cword.b.encdec = !encdec; /* in the rest of cryptoapi ENC=1/DEC=0 */
 407         data->cword.b.rounds = 10 + (ctx->key_length - 16) / 4;
 408         data->cword.b.ksize = (ctx->key_length - 16) / 8;
 409
 410         /* Is the hardware capable to generate the extended key? */
 411         if (!aes_hw_extkey_available(ctx->key_length))
 412                 data->cword.b.keygen = 1;
 413
 414         /* ctx->E starts with a plain key - if the hardware is capable
 415            to generate the extended key itself we must supply
 416            the plain key for both Encryption and Decryption. */
 417         if (encdec == CRYPTO_DIR_ENCRYPT || data->cword.b.keygen == 0)
 418                 key = ctx->E;
 419         else
 420                 key = ctx->D;
 421
 422         memcpy(data->buf, in_arg, AES_BLOCK_SIZE);
 423         padlock_xcrypt_ecb(data->buf, data->buf, key, &data->cword, 1);
 424         memcpy(out_arg, data->buf, AES_BLOCK_SIZE);
 425 }
 426
 427 static void
 428 aes_encrypt(void *ctx_arg, uint8_t *out, const uint8_t *in)
 429 {
 430         aes_padlock(ctx_arg, out, in, CRYPTO_DIR_ENCRYPT);
 431 }
 432
 433 static void
 434 aes_decrypt(void *ctx_arg, uint8_t *out, const uint8_t *in)
 435 {
 436         aes_padlock(ctx_arg, out, in, CRYPTO_DIR_DECRYPT);
 437 }
 438
 439 static struct crypto_alg aes_alg = {
 440         .cra_name               =       "aes",
 441         .cra_flags              =       CRYPTO_ALG_TYPE_CIPHER,
 442         .cra_blocksize          =       AES_BLOCK_SIZE,
 443         .cra_ctxsize            =       sizeof(struct aes_ctx),
 444         .cra_module             =       THIS_MODULE,
 445         .cra_list               =       LIST_HEAD_INIT(aes_alg.cra_list),
 446         .cra_u                  =       {
 447                 .cipher = {
 448                         .cia_min_keysize        =       AES_MIN_KEY_SIZE,
 449                         .cia_max_keysize        =       AES_MAX_KEY_SIZE,
 450                         .cia_setkey             =       aes_set_key,
 451                         .cia_encrypt            =       aes_encrypt,
 452                         .cia_decrypt            =       aes_decrypt
 453                 }
 454         }
 455 };
 456
 457 int __init padlock_init_aes(void)
 458 {
 459         printk(KERN_NOTICE PFX "Using VIA PadLock ACE for AES algorithm.\n");
 460
 461         gen_tabs();
 462         return crypto_register_alg(&aes_alg);
 463 }
 464
 465 void __exit padlock_fini_aes(void)
 466 {
 467         crypto_unregister_alg(&aes_alg);
 468 }