crypto/blkcipher.c

   1 /*
   2  * Block chaining cipher operations.
   3  *
   4  * Generic encrypt/decrypt wrapper for ciphers, handles operations across
   5  * multiple page boundaries by using temporary blocks.  In user context,
   6  * the kernel is given a chance to schedule us once per page.
   7  *
   8  * Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au>
   9  *
  10  * This program is free software; you can redistribute it and/or modify it
  11  * under the terms of the GNU General Public License as published by the Free
  12  * Software Foundation; either version 2 of the License, or (at your option)
  13  * any later version.
  14  *
  15  */
  16
  17 #include <linux/crypto.h>
  18 #include <linux/errno.h>
  19 #include <linux/hardirq.h>
  20 #include <linux/kernel.h>
  21 #include <linux/module.h>
  22 #include <linux/scatterlist.h>
  23 #include <linux/seq_file.h>
  24 #include <linux/slab.h>
  25 #include <linux/string.h>
  26
  27 #include "internal.h"
  28 #include "scatterwalk.h"
  29
  30 enum {
  31         BLKCIPHER_WALK_PHYS = 1 << 0,
  32         BLKCIPHER_WALK_SLOW = 1 << 1,
  33         BLKCIPHER_WALK_COPY = 1 << 2,
  34         BLKCIPHER_WALK_DIFF = 1 << 3,
  35 };
  36
  37 static int blkcipher_walk_next(struct blkcipher_desc *desc,
  38                                struct blkcipher_walk *walk);
  39 static int blkcipher_walk_first(struct blkcipher_desc *desc,
  40                                 struct blkcipher_walk *walk);
  41
  42 static inline void blkcipher_map_src(struct blkcipher_walk *walk)
  43 {
  44         walk->src.virt.addr = scatterwalk_map(&walk->in, 0);
  45 }
  46
  47 static inline void blkcipher_map_dst(struct blkcipher_walk *walk)
  48 {
  49         walk->dst.virt.addr = scatterwalk_map(&walk->out, 1);
  50 }
  51
  52 static inline void blkcipher_unmap_src(struct blkcipher_walk *walk)
  53 {
  54         scatterwalk_unmap(walk->src.virt.addr, 0);
  55 }
  56
  57 static inline void blkcipher_unmap_dst(struct blkcipher_walk *walk)
  58 {
  59         scatterwalk_unmap(walk->dst.virt.addr, 1);
  60 }
  61
  62 /* Get a spot of the specified length that does not straddle a page.
  63  * The caller needs to ensure that there is enough space for this operation.
  64  */
  65 static inline u8 *blkcipher_get_spot(u8 *start, unsigned int len)
  66 {
  67         u8 *end_page = (u8 *)(((unsigned long)(start + len - 1)) & PAGE_MASK);
  68         return max(start, end_page);
  69 }
  70
  71 static inline unsigned int blkcipher_done_slow(struct crypto_blkcipher *tfm,
  72                                                struct blkcipher_walk *walk,
  73                                                unsigned int bsize)
  74 {
  75         u8 *addr;
  76         unsigned int alignmask = crypto_blkcipher_alignmask(tfm);
  77
  78         addr = (u8 *)ALIGN((unsigned long)walk->buffer, alignmask + 1);
  79         addr = blkcipher_get_spot(addr, bsize);
  80         scatterwalk_copychunks(addr, &walk->out, bsize, 1);
  81         return bsize;
  82 }
  83
  84 static inline unsigned int blkcipher_done_fast(struct blkcipher_walk *walk,
  85                                                unsigned int n)
  86 {
  87         if (walk->flags & BLKCIPHER_WALK_COPY) {
  88                 blkcipher_map_dst(walk);
  89                 memcpy(walk->dst.virt.addr, walk->page, n);
  90                 blkcipher_unmap_dst(walk);
  91         } else if (!(walk->flags & BLKCIPHER_WALK_PHYS)) {
  92                 blkcipher_unmap_src(walk);
  93                 if (walk->flags & BLKCIPHER_WALK_DIFF)
  94                         blkcipher_unmap_dst(walk);
  95         }
  96
  97         scatterwalk_advance(&walk->in, n);
  98         scatterwalk_advance(&walk->out, n);
  99
 100         return n;
 101 }
 102
 103 int blkcipher_walk_done(struct blkcipher_desc *desc,
 104                         struct blkcipher_walk *walk, int err)
 105 {
 106         struct crypto_blkcipher *tfm = desc->tfm;
 107         unsigned int nbytes = 0;
 108
 109         if (likely(err >= 0)) {
 110                 unsigned int n = walk->nbytes - err;
 111
 112                 if (likely(!(walk->flags & BLKCIPHER_WALK_SLOW)))
 113                         n = blkcipher_done_fast(walk, n);
 114                 else if (WARN_ON(err)) {
 115                         err = -EINVAL;
 116                         goto err;
 117                 } else
 118                         n = blkcipher_done_slow(tfm, walk, n);
 119
 120                 nbytes = walk->total - n;
 121                 err = 0;
 122         }
 123
 124         scatterwalk_done(&walk->in, 0, nbytes);
 125         scatterwalk_done(&walk->out, 1, nbytes);
 126
 127         walk->total = nbytes;
 128         walk->nbytes = nbytes;
 129
 130         if (nbytes) {
 131                 crypto_yield(desc->flags);
 132                 return blkcipher_walk_next(desc, walk);
 133         }
 134
 135 err:
 136         if (walk->iv != desc->info)
 137                 memcpy(desc->info, walk->iv, crypto_blkcipher_ivsize(tfm));
 138         if (walk->buffer != walk->page)
 139                 kfree(walk->buffer);
 140         if (walk->page)
 141                 free_page((unsigned long)walk->page);
 142
 143         return err;
 144 }
 145 EXPORT_SYMBOL_GPL(blkcipher_walk_done);
 146
 147 static inline int blkcipher_next_slow(struct blkcipher_desc *desc,
 148                                       struct blkcipher_walk *walk,
 149                                       unsigned int bsize,
 150                                       unsigned int alignmask)
 151 {
 152         unsigned int n;
 153         unsigned aligned_bsize = ALIGN(bsize, alignmask + 1);
 154
 155         if (walk->buffer)
 156                 goto ok;
 157
 158         walk->buffer = walk->page;
 159         if (walk->buffer)
 160                 goto ok;
 161
 162         n = aligned_bsize * 3 - (alignmask + 1) +
 163             (alignmask & ~(crypto_tfm_ctx_alignment() - 1));
 164         walk->buffer = kmalloc(n, GFP_ATOMIC);
 165         if (!walk->buffer)
 166                 return blkcipher_walk_done(desc, walk, -ENOMEM);
 167
 168 ok:
 169         walk->dst.virt.addr = (u8 *)ALIGN((unsigned long)walk->buffer,
 170                                           alignmask + 1);
 171         walk->dst.virt.addr = blkcipher_get_spot(walk->dst.virt.addr, bsize);
 172         walk->src.virt.addr = blkcipher_get_spot(walk->dst.virt.addr +
 173                                                  aligned_bsize, bsize);
 174
 175         scatterwalk_copychunks(walk->src.virt.addr, &walk->in, bsize, 0);
 176
 177         walk->nbytes = bsize;
 178         walk->flags |= BLKCIPHER_WALK_SLOW;
 179
 180         return 0;
 181 }
 182
 183 static inline int blkcipher_next_copy(struct blkcipher_walk *walk)
 184 {
 185         u8 *tmp = walk->page;
 186
 187         blkcipher_map_src(walk);
 188         memcpy(tmp, walk->src.virt.addr, walk->nbytes);
 189         blkcipher_unmap_src(walk);
 190
 191         walk->src.virt.addr = tmp;
 192         walk->dst.virt.addr = tmp;
 193
 194         return 0;
 195 }
 196
 197 static inline int blkcipher_next_fast(struct blkcipher_desc *desc,
 198                                       struct blkcipher_walk *walk)
 199 {
 200         unsigned long diff;
 201
 202         walk->src.phys.page = scatterwalk_page(&walk->in);
 203         walk->src.phys.offset = offset_in_page(walk->in.offset);
 204         walk->dst.phys.page = scatterwalk_page(&walk->out);
 205         walk->dst.phys.offset = offset_in_page(walk->out.offset);
 206
 207         if (walk->flags & BLKCIPHER_WALK_PHYS)
 208                 return 0;
 209
 210         diff = walk->src.phys.offset - walk->dst.phys.offset;
 211         diff |= walk->src.virt.page - walk->dst.virt.page;
 212
 213         blkcipher_map_src(walk);
 214         walk->dst.virt.addr = walk->src.virt.addr;
 215
 216         if (diff) {
 217                 walk->flags |= BLKCIPHER_WALK_DIFF;
 218                 blkcipher_map_dst(walk);
 219         }
 220
 221         return 0;
 222 }
 223
 224 static int blkcipher_walk_next(struct blkcipher_desc *desc,
 225                                struct blkcipher_walk *walk)
 226 {
 227         struct crypto_blkcipher *tfm = desc->tfm;
 228         unsigned int alignmask = crypto_blkcipher_alignmask(tfm);
 229         unsigned int bsize;
 230         unsigned int n;
 231         int err;
 232
 233         n = walk->total;
 234         if (unlikely(n < crypto_blkcipher_blocksize(tfm))) {
 235                 desc->flags |= CRYPTO_TFM_RES_BAD_BLOCK_LEN;
 236                 return blkcipher_walk_done(desc, walk, -EINVAL);
 237         }
 238
 239         walk->flags &= ~(BLKCIPHER_WALK_SLOW | BLKCIPHER_WALK_COPY |
 240                          BLKCIPHER_WALK_DIFF);
 241         if (!scatterwalk_aligned(&walk->in, alignmask) ||
 242             !scatterwalk_aligned(&walk->out, alignmask)) {
 243                 walk->flags |= BLKCIPHER_WALK_COPY;
 244                 if (!walk->page) {
 245                         walk->page = (void *)__get_free_page(GFP_ATOMIC);
 246                         if (!walk->page)
 247                                 n = 0;
 248                 }
 249         }
 250
 251         bsize = min(walk->blocksize, n);
 252         n = scatterwalk_clamp(&walk->in, n);
 253         n = scatterwalk_clamp(&walk->out, n);
 254
 255         if (unlikely(n < bsize)) {
 256                 err = blkcipher_next_slow(desc, walk, bsize, alignmask);
 257                 goto set_phys_lowmem;
 258         }
 259
 260         walk->nbytes = n;
 261         if (walk->flags & BLKCIPHER_WALK_COPY) {
 262                 err = blkcipher_next_copy(walk);
 263                 goto set_phys_lowmem;
 264         }
 265
 266         return blkcipher_next_fast(desc, walk);
 267
 268 set_phys_lowmem:
 269         if (walk->flags & BLKCIPHER_WALK_PHYS) {
 270                 walk->src.phys.page = virt_to_page(walk->src.virt.addr);
 271                 walk->dst.phys.page = virt_to_page(walk->dst.virt.addr);
 272                 walk->src.phys.offset &= PAGE_SIZE - 1;
 273                 walk->dst.phys.offset &= PAGE_SIZE - 1;
 274         }
 275         return err;
 276 }
 277
 278 static inline int blkcipher_copy_iv(struct blkcipher_walk *walk,
 279                                     struct crypto_blkcipher *tfm,
 280                                     unsigned int alignmask)
 281 {
 282         unsigned bs = walk->blocksize;
 283         unsigned int ivsize = crypto_blkcipher_ivsize(tfm);
 284         unsigned aligned_bs = ALIGN(bs, alignmask + 1);
 285         unsigned int size = aligned_bs * 2 + ivsize + max(aligned_bs, ivsize) -
 286                             (alignmask + 1);
 287         u8 *iv;
 288
 289         size += alignmask & ~(crypto_tfm_ctx_alignment() - 1);
 290         walk->buffer = kmalloc(size, GFP_ATOMIC);
 291         if (!walk->buffer)
 292                 return -ENOMEM;
 293
 294         iv = (u8 *)ALIGN((unsigned long)walk->buffer, alignmask + 1);
 295         iv = blkcipher_get_spot(iv, bs) + aligned_bs;
 296         iv = blkcipher_get_spot(iv, bs) + aligned_bs;
 297         iv = blkcipher_get_spot(iv, ivsize);
 298
 299         walk->iv = memcpy(iv, walk->iv, ivsize);
 300         return 0;
 301 }
 302
 303 int blkcipher_walk_virt(struct blkcipher_desc *desc,
 304                         struct blkcipher_walk *walk)
 305 {
 306         walk->flags &= ~BLKCIPHER_WALK_PHYS;
 307         walk->blocksize = crypto_blkcipher_blocksize(desc->tfm);
 308         return blkcipher_walk_first(desc, walk);
 309 }
 310 EXPORT_SYMBOL_GPL(blkcipher_walk_virt);
 311
 312 int blkcipher_walk_phys(struct blkcipher_desc *desc,
 313                         struct blkcipher_walk *walk)
 314 {
 315         walk->flags |= BLKCIPHER_WALK_PHYS;
 316         walk->blocksize = crypto_blkcipher_blocksize(desc->tfm);
 317         return blkcipher_walk_first(desc, walk);
 318 }
 319 EXPORT_SYMBOL_GPL(blkcipher_walk_phys);
 320
 321 static int blkcipher_walk_first(struct blkcipher_desc *desc,
 322                                 struct blkcipher_walk *walk)
 323 {
 324         struct crypto_blkcipher *tfm = desc->tfm;
 325         unsigned int alignmask = crypto_blkcipher_alignmask(tfm);
 326
 327         if (WARN_ON_ONCE(in_irq()))
 328                 return -EDEADLK;
 329
 330         walk->nbytes = walk->total;
 331         if (unlikely(!walk->total))
 332                 return 0;
 333
 334         walk->buffer = NULL;
 335         walk->iv = desc->info;
 336         if (unlikely(((unsigned long)walk->iv & alignmask))) {
 337                 int err = blkcipher_copy_iv(walk, tfm, alignmask);
 338                 if (err)
 339                         return err;
 340         }
 341
 342         scatterwalk_start(&walk->in, walk->in.sg);
 343         scatterwalk_start(&walk->out, walk->out.sg);
 344         walk->page = NULL;
 345
 346         return blkcipher_walk_next(desc, walk);
 347 }
 348
 349 int blkcipher_walk_virt_block(struct blkcipher_desc *desc,
 350                               struct blkcipher_walk *walk,
 351                               unsigned int blocksize)
 352 {
 353         walk->flags &= ~BLKCIPHER_WALK_PHYS;
 354         walk->blocksize = blocksize;
 355         return blkcipher_walk_first(desc, walk);
 356 }
 357 EXPORT_SYMBOL_GPL(blkcipher_walk_virt_block);
 358
 359 static int setkey_unaligned(struct crypto_tfm *tfm, const u8 *key,
 360                             unsigned int keylen)
 361 {
 362         struct blkcipher_alg *cipher = &tfm->__crt_alg->cra_blkcipher;
 363         unsigned long alignmask = crypto_tfm_alg_alignmask(tfm);
 364         int ret;
 365         u8 *buffer, *alignbuffer;
 366         unsigned long absize;
 367
 368         absize = keylen + alignmask;
 369         buffer = kmalloc(absize, GFP_ATOMIC);
 370         if (!buffer)
 371                 return -ENOMEM;
 372
 373         alignbuffer = (u8 *)ALIGN((unsigned long)buffer, alignmask + 1);
 374         memcpy(alignbuffer, key, keylen);
 375         ret = cipher->setkey(tfm, alignbuffer, keylen);
 376         memset(alignbuffer, 0, keylen);
 377         kfree(buffer);
 378         return ret;
 379 }
 380
 381 static int setkey(struct crypto_tfm *tfm, const u8 *key, unsigned int keylen)
 382 {
 383         struct blkcipher_alg *cipher = &tfm->__crt_alg->cra_blkcipher;
 384         unsigned long alignmask = crypto_tfm_alg_alignmask(tfm);
 385
 386         if (keylen < cipher->min_keysize || keylen > cipher->max_keysize) {
 387                 tfm->crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
 388                 return -EINVAL;
 389         }
 390
 391         if ((unsigned long)key & alignmask)
 392                 return setkey_unaligned(tfm, key, keylen);
 393
 394         return cipher->setkey(tfm, key, keylen);
 395 }
 396
 397 static int async_setkey(struct crypto_ablkcipher *tfm, const u8 *key,
 398                         unsigned int keylen)
 399 {
 400         return setkey(crypto_ablkcipher_tfm(tfm), key, keylen);
 401 }
 402
 403 static int async_encrypt(struct ablkcipher_request *req)
 404 {
 405         struct crypto_tfm *tfm = req->base.tfm;
 406         struct blkcipher_alg *alg = &tfm->__crt_alg->cra_blkcipher;
 407         struct blkcipher_desc desc = {
 408                 .tfm = __crypto_blkcipher_cast(tfm),
 409                 .info = req->info,
 410                 .flags = req->base.flags,
 411         };
 412
 413
 414         return alg->encrypt(&desc, req->dst, req->src, req->nbytes);
 415 }
 416
 417 static int async_decrypt(struct ablkcipher_request *req)
 418 {
 419         struct crypto_tfm *tfm = req->base.tfm;
 420         struct blkcipher_alg *alg = &tfm->__crt_alg->cra_blkcipher;
 421         struct blkcipher_desc desc = {
 422                 .tfm = __crypto_blkcipher_cast(tfm),
 423                 .info = req->info,
 424                 .flags = req->base.flags,
 425         };
 426
 427         return alg->decrypt(&desc, req->dst, req->src, req->nbytes);
 428 }
 429
 430 static unsigned int crypto_blkcipher_ctxsize(struct crypto_alg *alg, u32 type,
 431                                              u32 mask)
 432 {
 433         struct blkcipher_alg *cipher = &alg->cra_blkcipher;
 434         unsigned int len = alg->cra_ctxsize;
 435
 436         type ^= CRYPTO_ALG_ASYNC;
 437         mask &= CRYPTO_ALG_ASYNC;
 438         if ((type & mask) && cipher->ivsize) {
 439                 len = ALIGN(len, (unsigned long)alg->cra_alignmask + 1);
 440                 len += cipher->ivsize;
 441         }
 442
 443         return len;
 444 }
 445
 446 static int crypto_init_blkcipher_ops_async(struct crypto_tfm *tfm)
 447 {
 448         struct ablkcipher_tfm *crt = &tfm->crt_ablkcipher;
 449         struct blkcipher_alg *alg = &tfm->__crt_alg->cra_blkcipher;
 450
 451         crt->setkey = async_setkey;
 452         crt->encrypt = async_encrypt;
 453         crt->decrypt = async_decrypt;
 454         crt->ivsize = alg->ivsize;
 455
 456         return 0;
 457 }
 458
 459 static int crypto_init_blkcipher_ops_sync(struct crypto_tfm *tfm)
 460 {
 461         struct blkcipher_tfm *crt = &tfm->crt_blkcipher;
 462         struct blkcipher_alg *alg = &tfm->__crt_alg->cra_blkcipher;
 463         unsigned long align = crypto_tfm_alg_alignmask(tfm) + 1;
 464         unsigned long addr;
 465
 466         crt->setkey = setkey;
 467         crt->encrypt = alg->encrypt;
 468         crt->decrypt = alg->decrypt;
 469
 470         addr = (unsigned long)crypto_tfm_ctx(tfm);
 471         addr = ALIGN(addr, align);
 472         addr += ALIGN(tfm->__crt_alg->cra_ctxsize, align);
 473         crt->iv = (void *)addr;
 474
 475         return 0;
 476 }
 477
 478 static int crypto_init_blkcipher_ops(struct crypto_tfm *tfm, u32 type, u32 mask)
 479 {
 480         struct blkcipher_alg *alg = &tfm->__crt_alg->cra_blkcipher;
 481
 482         if (alg->ivsize > PAGE_SIZE / 8)
 483                 return -EINVAL;
 484
 485         type ^= CRYPTO_ALG_ASYNC;
 486         mask &= CRYPTO_ALG_ASYNC;
 487         if (type & mask)
 488                 return crypto_init_blkcipher_ops_sync(tfm);
 489         else
 490                 return crypto_init_blkcipher_ops_async(tfm);
 491 }
 492
 493 static void crypto_blkcipher_show(struct seq_file *m, struct crypto_alg *alg)
 494         __attribute__ ((unused));
 495 static void crypto_blkcipher_show(struct seq_file *m, struct crypto_alg *alg)
 496 {
 497         seq_printf(m, "type         : blkcipher\n");
 498         seq_printf(m, "blocksize    : %u\n", alg->cra_blocksize);
 499         seq_printf(m, "min keysize  : %u\n", alg->cra_blkcipher.min_keysize);
 500         seq_printf(m, "max keysize  : %u\n", alg->cra_blkcipher.max_keysize);
 501         seq_printf(m, "ivsize       : %u\n", alg->cra_blkcipher.ivsize);
 502 }
 503
 504 const struct crypto_type crypto_blkcipher_type = {
 505         .ctxsize = crypto_blkcipher_ctxsize,
 506         .init = crypto_init_blkcipher_ops,
 507 #ifdef CONFIG_PROC_FS
 508         .show = crypto_blkcipher_show,
 509 #endif
 510 };
 511 EXPORT_SYMBOL_GPL(crypto_blkcipher_type);
 512
 513 MODULE_LICENSE("GPL");
 514 MODULE_DESCRIPTION("Generic block chaining cipher type");