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  */
   9
  10 #include <crypto/algapi.h>
  11 #include <crypto/aes.h>
  12 #include <linux/module.h>
  13 #include <linux/init.h>
  14 #include <linux/types.h>
  15 #include <linux/errno.h>
  16 #include <linux/interrupt.h>
  17 #include <linux/kernel.h>
  18 #include <linux/percpu.h>
  19 #include <linux/smp.h>
  20 #include <asm/byteorder.h>
  21 #include <asm/processor.h>
  22 #include <asm/i387.h>
  23 #include "padlock.h"
  24
  25 /*
  26  * Number of data blocks actually fetched for each xcrypt insn.
  27  * Processors with prefetch errata will fetch extra blocks.
  28  */
  29 static unsigned int ecb_fetch_blocks = 2;
  30 #define MAX_ECB_FETCH_BLOCKS (8)
  31 #define ecb_fetch_bytes (ecb_fetch_blocks * AES_BLOCK_SIZE)
  32
  33 static unsigned int cbc_fetch_blocks = 1;
  34 #define MAX_CBC_FETCH_BLOCKS (4)
  35 #define cbc_fetch_bytes (cbc_fetch_blocks * AES_BLOCK_SIZE)
  36
  37 /* Control word. */
  38 struct cword {
  39         unsigned int __attribute__ ((__packed__))
  40                 rounds:4,
  41                 algo:3,
  42                 keygen:1,
  43                 interm:1,
  44                 encdec:1,
  45                 ksize:2;
  46 } __attribute__ ((__aligned__(PADLOCK_ALIGNMENT)));
  47
  48 /* Whenever making any changes to the following
  49  * structure *make sure* you keep E, d_data
  50  * and cword aligned on 16 Bytes boundaries and
  51  * the Hardware can access 16 * 16 bytes of E and d_data
  52  * (only the first 15 * 16 bytes matter but the HW reads
  53  * more).
  54  */
  55 struct aes_ctx {
  56         u32 E[AES_MAX_KEYLENGTH_U32]
  57                 __attribute__ ((__aligned__(PADLOCK_ALIGNMENT)));
  58         u32 d_data[AES_MAX_KEYLENGTH_U32]
  59                 __attribute__ ((__aligned__(PADLOCK_ALIGNMENT)));
  60         struct {
  61                 struct cword encrypt;
  62                 struct cword decrypt;
  63         } cword;
  64         u32 *D;
  65 };
  66
  67 static DEFINE_PER_CPU(struct cword *, paes_last_cword);
  68
  69 /* Tells whether the ACE is capable to generate
  70    the extended key for a given key_len. */
  71 static inline int
  72 aes_hw_extkey_available(uint8_t key_len)
  73 {
  74         /* TODO: We should check the actual CPU model/stepping
  75                  as it's possible that the capability will be
  76                  added in the next CPU revisions. */
  77         if (key_len == 16)
  78                 return 1;
  79         return 0;
  80 }
  81
  82 static inline struct aes_ctx *aes_ctx_common(void *ctx)
  83 {
  84         unsigned long addr = (unsigned long)ctx;
  85         unsigned long align = PADLOCK_ALIGNMENT;
  86
  87         if (align <= crypto_tfm_ctx_alignment())
  88                 align = 1;
  89         return (struct aes_ctx *)ALIGN(addr, align);
  90 }
  91
  92 static inline struct aes_ctx *aes_ctx(struct crypto_tfm *tfm)
  93 {
  94         return aes_ctx_common(crypto_tfm_ctx(tfm));
  95 }
  96
  97 static inline struct aes_ctx *blk_aes_ctx(struct crypto_blkcipher *tfm)
  98 {
  99         return aes_ctx_common(crypto_blkcipher_ctx(tfm));
 100 }
 101
 102 static int aes_set_key(struct crypto_tfm *tfm, const u8 *in_key,
 103                        unsigned int key_len)
 104 {
 105         struct aes_ctx *ctx = aes_ctx(tfm);
 106         const __le32 *key = (const __le32 *)in_key;
 107         u32 *flags = &tfm->crt_flags;
 108         struct crypto_aes_ctx gen_aes;
 109         int cpu;
 110
 111         if (key_len % 8) {
 112                 *flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
 113                 return -EINVAL;
 114         }
 115
 116         /*
 117          * If the hardware is capable of generating the extended key
 118          * itself we must supply the plain key for both encryption
 119          * and decryption.
 120          */
 121         ctx->D = ctx->E;
 122
 123         ctx->E[0] = le32_to_cpu(key[0]);
 124         ctx->E[1] = le32_to_cpu(key[1]);
 125         ctx->E[2] = le32_to_cpu(key[2]);
 126         ctx->E[3] = le32_to_cpu(key[3]);
 127
 128         /* Prepare control words. */
 129         memset(&ctx->cword, 0, sizeof(ctx->cword));
 130
 131         ctx->cword.decrypt.encdec = 1;
 132         ctx->cword.encrypt.rounds = 10 + (key_len - 16) / 4;
 133         ctx->cword.decrypt.rounds = ctx->cword.encrypt.rounds;
 134         ctx->cword.encrypt.ksize = (key_len - 16) / 8;
 135         ctx->cword.decrypt.ksize = ctx->cword.encrypt.ksize;
 136
 137         /* Don't generate extended keys if the hardware can do it. */
 138         if (aes_hw_extkey_available(key_len))
 139                 goto ok;
 140
 141         ctx->D = ctx->d_data;
 142         ctx->cword.encrypt.keygen = 1;
 143         ctx->cword.decrypt.keygen = 1;
 144
 145         if (crypto_aes_expand_key(&gen_aes, in_key, key_len)) {
 146                 *flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
 147                 return -EINVAL;
 148         }
 149
 150         memcpy(ctx->E, gen_aes.key_enc, AES_MAX_KEYLENGTH);
 151         memcpy(ctx->D, gen_aes.key_dec, AES_MAX_KEYLENGTH);
 152
 153 ok:
 154         for_each_online_cpu(cpu)
 155                 if (&ctx->cword.encrypt == per_cpu(paes_last_cword, cpu) ||
 156                     &ctx->cword.decrypt == per_cpu(paes_last_cword, cpu))
 157                         per_cpu(paes_last_cword, cpu) = NULL;
 158
 159         return 0;
 160 }
 161
 162 /* ====== Encryption/decryption routines ====== */
 163
 164 /* These are the real call to PadLock. */
 165 static inline void padlock_reset_key(struct cword *cword)
 166 {
 167         int cpu = raw_smp_processor_id();
 168
 169         if (cword != per_cpu(paes_last_cword, cpu))
 170 #ifndef CONFIG_X86_64
 171                 asm volatile ("pushfl; popfl");
 172 #else
 173                 asm volatile ("pushfq; popfq");
 174 #endif
 175 }
 176
 177 static inline void padlock_store_cword(struct cword *cword)
 178 {
 179         per_cpu(paes_last_cword, raw_smp_processor_id()) = cword;
 180 }
 181
 182 /*
 183  * While the padlock instructions don't use FP/SSE registers, they
 184  * generate a spurious DNA fault when cr0.ts is '1'. These instructions
 185  * should be used only inside the irq_ts_save/restore() context
 186  */
 187
 188 static inline void rep_xcrypt_ecb(const u8 *input, u8 *output, void *key,
 189                                   struct cword *control_word, int count)
 190 {
 191         asm volatile (".byte 0xf3,0x0f,0xa7,0xc8"       /* rep xcryptecb */
 192                       : "+S"(input), "+D"(output)
 193                       : "d"(control_word), "b"(key), "c"(count));
 194 }
 195
 196 static inline u8 *rep_xcrypt_cbc(const u8 *input, u8 *output, void *key,
 197                                  u8 *iv, struct cword *control_word, int count)
 198 {
 199         asm volatile (".byte 0xf3,0x0f,0xa7,0xd0"       /* rep xcryptcbc */
 200                       : "+S" (input), "+D" (output), "+a" (iv)
 201                       : "d" (control_word), "b" (key), "c" (count));
 202         return iv;
 203 }
 204
 205 static void ecb_crypt_copy(const u8 *in, u8 *out, u32 *key,
 206                            struct cword *cword, int count)
 207 {
 208         /*
 209          * Padlock prefetches extra data so we must provide mapped input buffers.
 210          * Assume there are at least 16 bytes of stack already in use.
 211          */
 212         u8 buf[AES_BLOCK_SIZE * (MAX_ECB_FETCH_BLOCKS - 1) + PADLOCK_ALIGNMENT - 1];
 213         u8 *tmp = PTR_ALIGN(&buf[0], PADLOCK_ALIGNMENT);
 214
 215         memcpy(tmp, in, count * AES_BLOCK_SIZE);
 216         rep_xcrypt_ecb(tmp, out, key, cword, count);
 217 }
 218
 219 static u8 *cbc_crypt_copy(const u8 *in, u8 *out, u32 *key,
 220                            u8 *iv, struct cword *cword, int count)
 221 {
 222         /*
 223          * Padlock prefetches extra data so we must provide mapped input buffers.
 224          * Assume there are at least 16 bytes of stack already in use.
 225          */
 226         u8 buf[AES_BLOCK_SIZE * (MAX_CBC_FETCH_BLOCKS - 1) + PADLOCK_ALIGNMENT - 1];
 227         u8 *tmp = PTR_ALIGN(&buf[0], PADLOCK_ALIGNMENT);
 228
 229         memcpy(tmp, in, count * AES_BLOCK_SIZE);
 230         return rep_xcrypt_cbc(tmp, out, key, iv, cword, count);
 231 }
 232
 233 static inline void ecb_crypt(const u8 *in, u8 *out, u32 *key,
 234                              struct cword *cword, int count)
 235 {
 236         /* Padlock in ECB mode fetches at least ecb_fetch_bytes of data.
 237          * We could avoid some copying here but it's probably not worth it.
 238          */
 239         if (unlikely(((unsigned long)in & ~PAGE_MASK) + ecb_fetch_bytes > PAGE_SIZE)) {
 240                 ecb_crypt_copy(in, out, key, cword, count);
 241                 return;
 242         }
 243
 244         rep_xcrypt_ecb(in, out, key, cword, count);
 245 }
 246
 247 static inline u8 *cbc_crypt(const u8 *in, u8 *out, u32 *key,
 248                             u8 *iv, struct cword *cword, int count)
 249 {
 250         /* Padlock in CBC mode fetches at least cbc_fetch_bytes of data. */
 251         if (unlikely(((unsigned long)in & ~PAGE_MASK) + cbc_fetch_bytes > PAGE_SIZE))
 252                 return cbc_crypt_copy(in, out, key, iv, cword, count);
 253
 254         return rep_xcrypt_cbc(in, out, key, iv, cword, count);
 255 }
 256
 257 static inline void padlock_xcrypt_ecb(const u8 *input, u8 *output, void *key,
 258                                       void *control_word, u32 count)
 259 {
 260         u32 initial = count & (ecb_fetch_blocks - 1);
 261
 262         if (count < ecb_fetch_blocks) {
 263                 ecb_crypt(input, output, key, control_word, count);
 264                 return;
 265         }
 266
 267         if (initial)
 268                 asm volatile (".byte 0xf3,0x0f,0xa7,0xc8"       /* rep xcryptecb */
 269                               : "+S"(input), "+D"(output)
 270                               : "d"(control_word), "b"(key), "c"(initial));
 271
 272         asm volatile (".byte 0xf3,0x0f,0xa7,0xc8"       /* rep xcryptecb */
 273                       : "+S"(input), "+D"(output)
 274                       : "d"(control_word), "b"(key), "c"(count - initial));
 275 }
 276
 277 static inline u8 *padlock_xcrypt_cbc(const u8 *input, u8 *output, void *key,
 278                                      u8 *iv, void *control_word, u32 count)
 279 {
 280         u32 initial = count & (cbc_fetch_blocks - 1);
 281
 282         if (count < cbc_fetch_blocks)
 283                 return cbc_crypt(input, output, key, iv, control_word, count);
 284
 285         if (initial)
 286                 asm volatile (".byte 0xf3,0x0f,0xa7,0xd0"       /* rep xcryptcbc */
 287                               : "+S" (input), "+D" (output), "+a" (iv)
 288                               : "d" (control_word), "b" (key), "c" (count));
 289
 290         asm volatile (".byte 0xf3,0x0f,0xa7,0xd0"       /* rep xcryptcbc */
 291                       : "+S" (input), "+D" (output), "+a" (iv)
 292                       : "d" (control_word), "b" (key), "c" (count-initial));
 293         return iv;
 294 }
 295
 296 static void aes_encrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
 297 {
 298         struct aes_ctx *ctx = aes_ctx(tfm);
 299         int ts_state;
 300
 301         padlock_reset_key(&ctx->cword.encrypt);
 302         ts_state = irq_ts_save();
 303         ecb_crypt(in, out, ctx->E, &ctx->cword.encrypt, 1);
 304         irq_ts_restore(ts_state);
 305         padlock_store_cword(&ctx->cword.encrypt);
 306 }
 307
 308 static void aes_decrypt(struct crypto_tfm *tfm, u8 *out, const u8 *in)
 309 {
 310         struct aes_ctx *ctx = aes_ctx(tfm);
 311         int ts_state;
 312
 313         padlock_reset_key(&ctx->cword.encrypt);
 314         ts_state = irq_ts_save();
 315         ecb_crypt(in, out, ctx->D, &ctx->cword.decrypt, 1);
 316         irq_ts_restore(ts_state);
 317         padlock_store_cword(&ctx->cword.encrypt);
 318 }
 319
 320 static struct crypto_alg aes_alg = {
 321         .cra_name               =       "aes",
 322         .cra_driver_name        =       "aes-padlock",
 323         .cra_priority           =       PADLOCK_CRA_PRIORITY,
 324         .cra_flags              =       CRYPTO_ALG_TYPE_CIPHER,
 325         .cra_blocksize          =       AES_BLOCK_SIZE,
 326         .cra_ctxsize            =       sizeof(struct aes_ctx),
 327         .cra_alignmask          =       PADLOCK_ALIGNMENT - 1,
 328         .cra_module             =       THIS_MODULE,
 329         .cra_list               =       LIST_HEAD_INIT(aes_alg.cra_list),
 330         .cra_u                  =       {
 331                 .cipher = {
 332                         .cia_min_keysize        =       AES_MIN_KEY_SIZE,
 333                         .cia_max_keysize        =       AES_MAX_KEY_SIZE,
 334                         .cia_setkey             =       aes_set_key,
 335                         .cia_encrypt            =       aes_encrypt,
 336                         .cia_decrypt            =       aes_decrypt,
 337                 }
 338         }
 339 };
 340
 341 static int ecb_aes_encrypt(struct blkcipher_desc *desc,
 342                            struct scatterlist *dst, struct scatterlist *src,
 343                            unsigned int nbytes)
 344 {
 345         struct aes_ctx *ctx = blk_aes_ctx(desc->tfm);
 346         struct blkcipher_walk walk;
 347         int err;
 348         int ts_state;
 349
 350         padlock_reset_key(&ctx->cword.encrypt);
 351
 352         blkcipher_walk_init(&walk, dst, src, nbytes);
 353         err = blkcipher_walk_virt(desc, &walk);
 354
 355         ts_state = irq_ts_save();
 356         while ((nbytes = walk.nbytes)) {
 357                 padlock_xcrypt_ecb(walk.src.virt.addr, walk.dst.virt.addr,
 358                                    ctx->E, &ctx->cword.encrypt,
 359                                    nbytes / AES_BLOCK_SIZE);
 360                 nbytes &= AES_BLOCK_SIZE - 1;
 361                 err = blkcipher_walk_done(desc, &walk, nbytes);
 362         }
 363         irq_ts_restore(ts_state);
 364
 365         padlock_store_cword(&ctx->cword.encrypt);
 366
 367         return err;
 368 }
 369
 370 static int ecb_aes_decrypt(struct blkcipher_desc *desc,
 371                            struct scatterlist *dst, struct scatterlist *src,
 372                            unsigned int nbytes)
 373 {
 374         struct aes_ctx *ctx = blk_aes_ctx(desc->tfm);
 375         struct blkcipher_walk walk;
 376         int err;
 377         int ts_state;
 378
 379         padlock_reset_key(&ctx->cword.decrypt);
 380
 381         blkcipher_walk_init(&walk, dst, src, nbytes);
 382         err = blkcipher_walk_virt(desc, &walk);
 383
 384         ts_state = irq_ts_save();
 385         while ((nbytes = walk.nbytes)) {
 386                 padlock_xcrypt_ecb(walk.src.virt.addr, walk.dst.virt.addr,
 387                                    ctx->D, &ctx->cword.decrypt,
 388                                    nbytes / AES_BLOCK_SIZE);
 389                 nbytes &= AES_BLOCK_SIZE - 1;
 390                 err = blkcipher_walk_done(desc, &walk, nbytes);
 391         }
 392         irq_ts_restore(ts_state);
 393
 394         padlock_store_cword(&ctx->cword.encrypt);
 395
 396         return err;
 397 }
 398
 399 static struct crypto_alg ecb_aes_alg = {
 400         .cra_name               =       "ecb(aes)",
 401         .cra_driver_name        =       "ecb-aes-padlock",
 402         .cra_priority           =       PADLOCK_COMPOSITE_PRIORITY,
 403         .cra_flags              =       CRYPTO_ALG_TYPE_BLKCIPHER,
 404         .cra_blocksize          =       AES_BLOCK_SIZE,
 405         .cra_ctxsize            =       sizeof(struct aes_ctx),
 406         .cra_alignmask          =       PADLOCK_ALIGNMENT - 1,
 407         .cra_type               =       &crypto_blkcipher_type,
 408         .cra_module             =       THIS_MODULE,
 409         .cra_list               =       LIST_HEAD_INIT(ecb_aes_alg.cra_list),
 410         .cra_u                  =       {
 411                 .blkcipher = {
 412                         .min_keysize            =       AES_MIN_KEY_SIZE,
 413                         .max_keysize            =       AES_MAX_KEY_SIZE,
 414                         .setkey                 =       aes_set_key,
 415                         .encrypt                =       ecb_aes_encrypt,
 416                         .decrypt                =       ecb_aes_decrypt,
 417                 }
 418         }
 419 };
 420
 421 static int cbc_aes_encrypt(struct blkcipher_desc *desc,
 422                            struct scatterlist *dst, struct scatterlist *src,
 423                            unsigned int nbytes)
 424 {
 425         struct aes_ctx *ctx = blk_aes_ctx(desc->tfm);
 426         struct blkcipher_walk walk;
 427         int err;
 428         int ts_state;
 429
 430         padlock_reset_key(&ctx->cword.encrypt);
 431
 432         blkcipher_walk_init(&walk, dst, src, nbytes);
 433         err = blkcipher_walk_virt(desc, &walk);
 434
 435         ts_state = irq_ts_save();
 436         while ((nbytes = walk.nbytes)) {
 437                 u8 *iv = padlock_xcrypt_cbc(walk.src.virt.addr,
 438                                             walk.dst.virt.addr, ctx->E,
 439                                             walk.iv, &ctx->cword.encrypt,
 440                                             nbytes / AES_BLOCK_SIZE);
 441                 memcpy(walk.iv, iv, AES_BLOCK_SIZE);
 442                 nbytes &= AES_BLOCK_SIZE - 1;
 443                 err = blkcipher_walk_done(desc, &walk, nbytes);
 444         }
 445         irq_ts_restore(ts_state);
 446
 447         padlock_store_cword(&ctx->cword.decrypt);
 448
 449         return err;
 450 }
 451
 452 static int cbc_aes_decrypt(struct blkcipher_desc *desc,
 453                            struct scatterlist *dst, struct scatterlist *src,
 454                            unsigned int nbytes)
 455 {
 456         struct aes_ctx *ctx = blk_aes_ctx(desc->tfm);
 457         struct blkcipher_walk walk;
 458         int err;
 459         int ts_state;
 460
 461         padlock_reset_key(&ctx->cword.encrypt);
 462
 463         blkcipher_walk_init(&walk, dst, src, nbytes);
 464         err = blkcipher_walk_virt(desc, &walk);
 465
 466         ts_state = irq_ts_save();
 467         while ((nbytes = walk.nbytes)) {
 468                 padlock_xcrypt_cbc(walk.src.virt.addr, walk.dst.virt.addr,
 469                                    ctx->D, walk.iv, &ctx->cword.decrypt,
 470                                    nbytes / AES_BLOCK_SIZE);
 471                 nbytes &= AES_BLOCK_SIZE - 1;
 472                 err = blkcipher_walk_done(desc, &walk, nbytes);
 473         }
 474
 475         irq_ts_restore(ts_state);
 476
 477         padlock_store_cword(&ctx->cword.encrypt);
 478
 479         return err;
 480 }
 481
 482 static struct crypto_alg cbc_aes_alg = {
 483         .cra_name               =       "cbc(aes)",
 484         .cra_driver_name        =       "cbc-aes-padlock",
 485         .cra_priority           =       PADLOCK_COMPOSITE_PRIORITY,
 486         .cra_flags              =       CRYPTO_ALG_TYPE_BLKCIPHER,
 487         .cra_blocksize          =       AES_BLOCK_SIZE,
 488         .cra_ctxsize            =       sizeof(struct aes_ctx),
 489         .cra_alignmask          =       PADLOCK_ALIGNMENT - 1,
 490         .cra_type               =       &crypto_blkcipher_type,
 491         .cra_module             =       THIS_MODULE,
 492         .cra_list               =       LIST_HEAD_INIT(cbc_aes_alg.cra_list),
 493         .cra_u                  =       {
 494                 .blkcipher = {
 495                         .min_keysize            =       AES_MIN_KEY_SIZE,
 496                         .max_keysize            =       AES_MAX_KEY_SIZE,
 497                         .ivsize                 =       AES_BLOCK_SIZE,
 498                         .setkey                 =       aes_set_key,
 499                         .encrypt                =       cbc_aes_encrypt,
 500                         .decrypt                =       cbc_aes_decrypt,
 501                 }
 502         }
 503 };
 504
 505 static int __init padlock_init(void)
 506 {
 507         int ret;
 508         struct cpuinfo_x86 *c = &cpu_data(0);
 509
 510         if (!cpu_has_xcrypt) {
 511                 printk(KERN_NOTICE PFX "VIA PadLock not detected.\n");
 512                 return -ENODEV;
 513         }
 514
 515         if (!cpu_has_xcrypt_enabled) {
 516                 printk(KERN_NOTICE PFX "VIA PadLock detected, but not enabled. Hmm, strange...\n");
 517                 return -ENODEV;
 518         }
 519
 520         if ((ret = crypto_register_alg(&aes_alg)))
 521                 goto aes_err;
 522
 523         if ((ret = crypto_register_alg(&ecb_aes_alg)))
 524                 goto ecb_aes_err;
 525
 526         if ((ret = crypto_register_alg(&cbc_aes_alg)))
 527                 goto cbc_aes_err;
 528
 529         printk(KERN_NOTICE PFX "Using VIA PadLock ACE for AES algorithm.\n");
 530
 531         if (c->x86 == 6 && c->x86_model == 15 && c->x86_mask == 2) {
 532                 ecb_fetch_blocks = MAX_ECB_FETCH_BLOCKS;
 533                 cbc_fetch_blocks = MAX_CBC_FETCH_BLOCKS;
 534                 printk(KERN_NOTICE PFX "VIA Nano stepping 2 detected: enabling workaround.\n");
 535         }
 536
 537 out:
 538         return ret;
 539
 540 cbc_aes_err:
 541         crypto_unregister_alg(&ecb_aes_alg);
 542 ecb_aes_err:
 543         crypto_unregister_alg(&aes_alg);
 544 aes_err:
 545         printk(KERN_ERR PFX "VIA PadLock AES initialization failed.\n");
 546         goto out;
 547 }
 548
 549 static void __exit padlock_fini(void)
 550 {
 551         crypto_unregister_alg(&cbc_aes_alg);
 552         crypto_unregister_alg(&ecb_aes_alg);
 553         crypto_unregister_alg(&aes_alg);
 554 }
 555
 556 module_init(padlock_init);
 557 module_exit(padlock_fini);
 558
 559 MODULE_DESCRIPTION("VIA PadLock AES algorithm support");
 560 MODULE_LICENSE("GPL");
 561 MODULE_AUTHOR("Michal Ludvig");
 562
 563 MODULE_ALIAS("aes");