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 start > end_page ? 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         n = walk->nbytes - n;
  88
  89         if (walk->flags & BLKCIPHER_WALK_COPY) {
  90                 blkcipher_map_dst(walk);
  91                 memcpy(walk->dst.virt.addr, walk->page, n);
  92                 blkcipher_unmap_dst(walk);
  93         } else if (!(walk->flags & BLKCIPHER_WALK_PHYS)) {
  94                 blkcipher_unmap_src(walk);
  95                 if (walk->flags & BLKCIPHER_WALK_DIFF)
  96                         blkcipher_unmap_dst(walk);
  97         }
  98
  99         scatterwalk_advance(&walk->in, n);
 100         scatterwalk_advance(&walk->out, n);
 101
 102         return n;
 103 }
 104
 105 int blkcipher_walk_done(struct blkcipher_desc *desc,
 106                         struct blkcipher_walk *walk, int err)
 107 {
 108         struct crypto_blkcipher *tfm = desc->tfm;
 109         unsigned int nbytes = 0;
 110
 111         if (likely(err >= 0)) {
 112                 unsigned int bsize = crypto_blkcipher_blocksize(tfm);
 113                 unsigned int n;
 114
 115                 if (likely(!(walk->flags & BLKCIPHER_WALK_SLOW)))
 116                         n = blkcipher_done_fast(walk, err);
 117                 else
 118                         n = blkcipher_done_slow(tfm, walk, bsize);
 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         if (walk->iv != desc->info)
 136                 memcpy(desc->info, walk->iv, crypto_blkcipher_ivsize(tfm));
 137         if (walk->buffer != walk->page)
 138                 kfree(walk->buffer);
 139         if (walk->page)
 140                 free_page((unsigned long)walk->page);
 141
 142         return err;
 143 }
 144 EXPORT_SYMBOL_GPL(blkcipher_walk_done);
 145
 146 static inline int blkcipher_next_slow(struct blkcipher_desc *desc,
 147                                       struct blkcipher_walk *walk,
 148                                       unsigned int bsize,
 149                                       unsigned int alignmask)
 150 {
 151         unsigned int n;
 152
 153         if (walk->buffer)
 154                 goto ok;
 155
 156         walk->buffer = walk->page;
 157         if (walk->buffer)
 158                 goto ok;
 159
 160         n = bsize * 3 - (alignmask + 1) +
 161             (alignmask & ~(crypto_tfm_ctx_alignment() - 1));
 162         walk->buffer = kmalloc(n, GFP_ATOMIC);
 163         if (!walk->buffer)
 164                 return blkcipher_walk_done(desc, walk, -ENOMEM);
 165
 166 ok:
 167         walk->dst.virt.addr = (u8 *)ALIGN((unsigned long)walk->buffer,
 168                                           alignmask + 1);
 169         walk->dst.virt.addr = blkcipher_get_spot(walk->dst.virt.addr, bsize);
 170         walk->src.virt.addr = blkcipher_get_spot(walk->dst.virt.addr + bsize,
 171                                                  bsize);
 172
 173         scatterwalk_copychunks(walk->src.virt.addr, &walk->in, bsize, 0);
 174
 175         walk->nbytes = bsize;
 176         walk->flags |= BLKCIPHER_WALK_SLOW;
 177
 178         return 0;
 179 }
 180
 181 static inline int blkcipher_next_copy(struct blkcipher_walk *walk)
 182 {
 183         u8 *tmp = walk->page;
 184
 185         blkcipher_map_src(walk);
 186         memcpy(tmp, walk->src.virt.addr, walk->nbytes);
 187         blkcipher_unmap_src(walk);
 188
 189         walk->src.virt.addr = tmp;
 190         walk->dst.virt.addr = tmp;
 191
 192         return 0;
 193 }
 194
 195 static inline int blkcipher_next_fast(struct blkcipher_desc *desc,
 196                                       struct blkcipher_walk *walk)
 197 {
 198         unsigned long diff;
 199
 200         walk->src.phys.page = scatterwalk_page(&walk->in);
 201         walk->src.phys.offset = offset_in_page(walk->in.offset);
 202         walk->dst.phys.page = scatterwalk_page(&walk->out);
 203         walk->dst.phys.offset = offset_in_page(walk->out.offset);
 204
 205         if (walk->flags & BLKCIPHER_WALK_PHYS)
 206                 return 0;
 207
 208         diff = walk->src.phys.offset - walk->dst.phys.offset;
 209         diff |= walk->src.virt.page - walk->dst.virt.page;
 210
 211         blkcipher_map_src(walk);
 212         walk->dst.virt.addr = walk->src.virt.addr;
 213
 214         if (diff) {
 215                 walk->flags |= BLKCIPHER_WALK_DIFF;
 216                 blkcipher_map_dst(walk);
 217         }
 218
 219         return 0;
 220 }
 221
 222 static int blkcipher_walk_next(struct blkcipher_desc *desc,
 223                                struct blkcipher_walk *walk)
 224 {
 225         struct crypto_blkcipher *tfm = desc->tfm;
 226         unsigned int alignmask = crypto_blkcipher_alignmask(tfm);
 227         unsigned int bsize = crypto_blkcipher_blocksize(tfm);
 228         unsigned int n;
 229         int err;
 230
 231         n = walk->total;
 232         if (unlikely(n < bsize)) {
 233                 desc->flags |= CRYPTO_TFM_RES_BAD_BLOCK_LEN;
 234                 return blkcipher_walk_done(desc, walk, -EINVAL);
 235         }
 236
 237         walk->flags &= ~(BLKCIPHER_WALK_SLOW | BLKCIPHER_WALK_COPY |
 238                          BLKCIPHER_WALK_DIFF);
 239         if (!scatterwalk_aligned(&walk->in, alignmask) ||
 240             !scatterwalk_aligned(&walk->out, alignmask)) {
 241                 walk->flags |= BLKCIPHER_WALK_COPY;
 242                 if (!walk->page) {
 243                         walk->page = (void *)__get_free_page(GFP_ATOMIC);
 244                         if (!walk->page)
 245                                 n = 0;
 246                 }
 247         }
 248
 249         n = scatterwalk_clamp(&walk->in, n);
 250         n = scatterwalk_clamp(&walk->out, n);
 251
 252         if (unlikely(n < bsize)) {
 253                 err = blkcipher_next_slow(desc, walk, bsize, alignmask);
 254                 goto set_phys_lowmem;
 255         }
 256
 257         walk->nbytes = n;
 258         if (walk->flags & BLKCIPHER_WALK_COPY) {
 259                 err = blkcipher_next_copy(walk);
 260                 goto set_phys_lowmem;
 261         }
 262
 263         return blkcipher_next_fast(desc, walk);
 264
 265 set_phys_lowmem:
 266         if (walk->flags & BLKCIPHER_WALK_PHYS) {
 267                 walk->src.phys.page = virt_to_page(walk->src.virt.addr);
 268                 walk->dst.phys.page = virt_to_page(walk->dst.virt.addr);
 269                 walk->src.phys.offset &= PAGE_SIZE - 1;
 270                 walk->dst.phys.offset &= PAGE_SIZE - 1;
 271         }
 272         return err;
 273 }
 274
 275 static inline int blkcipher_copy_iv(struct blkcipher_walk *walk,
 276                                     struct crypto_blkcipher *tfm,
 277                                     unsigned int alignmask)
 278 {
 279         unsigned bs = crypto_blkcipher_blocksize(tfm);
 280         unsigned int ivsize = crypto_blkcipher_ivsize(tfm);
 281         unsigned int size = bs * 2 + ivsize + max(bs, ivsize) - (alignmask + 1);
 282         u8 *iv;
 283
 284         size += alignmask & ~(crypto_tfm_ctx_alignment() - 1);
 285         walk->buffer = kmalloc(size, GFP_ATOMIC);
 286         if (!walk->buffer)
 287                 return -ENOMEM;
 288
 289         iv = (u8 *)ALIGN((unsigned long)walk->buffer, alignmask + 1);
 290         iv = blkcipher_get_spot(iv, bs) + bs;
 291         iv = blkcipher_get_spot(iv, bs) + bs;
 292         iv = blkcipher_get_spot(iv, ivsize);
 293
 294         walk->iv = memcpy(iv, walk->iv, ivsize);
 295         return 0;
 296 }
 297
 298 int blkcipher_walk_virt(struct blkcipher_desc *desc,
 299                         struct blkcipher_walk *walk)
 300 {
 301         walk->flags &= ~BLKCIPHER_WALK_PHYS;
 302         return blkcipher_walk_first(desc, walk);
 303 }
 304 EXPORT_SYMBOL_GPL(blkcipher_walk_virt);
 305
 306 int blkcipher_walk_phys(struct blkcipher_desc *desc,
 307                         struct blkcipher_walk *walk)
 308 {
 309         walk->flags |= BLKCIPHER_WALK_PHYS;
 310         return blkcipher_walk_first(desc, walk);
 311 }
 312 EXPORT_SYMBOL_GPL(blkcipher_walk_phys);
 313
 314 static int blkcipher_walk_first(struct blkcipher_desc *desc,
 315                                 struct blkcipher_walk *walk)
 316 {
 317         struct crypto_blkcipher *tfm = desc->tfm;
 318         unsigned int alignmask = crypto_blkcipher_alignmask(tfm);
 319
 320         if (WARN_ON_ONCE(in_irq()))
 321                 return -EDEADLK;
 322
 323         walk->nbytes = walk->total;
 324         if (unlikely(!walk->total))
 325                 return 0;
 326
 327         walk->buffer = NULL;
 328         walk->iv = desc->info;
 329         if (unlikely(((unsigned long)walk->iv & alignmask))) {
 330                 int err = blkcipher_copy_iv(walk, tfm, alignmask);
 331                 if (err)
 332                         return err;
 333         }
 334
 335         scatterwalk_start(&walk->in, walk->in.sg);
 336         scatterwalk_start(&walk->out, walk->out.sg);
 337         walk->page = NULL;
 338
 339         return blkcipher_walk_next(desc, walk);
 340 }
 341
 342 static int setkey_unaligned(struct crypto_tfm *tfm, const u8 *key, unsigned int keylen)
 343 {
 344         struct blkcipher_alg *cipher = &tfm->__crt_alg->cra_blkcipher;
 345         unsigned long alignmask = crypto_tfm_alg_alignmask(tfm);
 346         int ret;
 347         u8 *buffer, *alignbuffer;
 348         unsigned long absize;
 349
 350         absize = keylen + alignmask;
 351         buffer = kmalloc(absize, GFP_ATOMIC);
 352         if (!buffer)
 353                 return -ENOMEM;
 354
 355         alignbuffer = (u8 *)ALIGN((unsigned long)buffer, alignmask + 1);
 356         memcpy(alignbuffer, key, keylen);
 357         ret = cipher->setkey(tfm, alignbuffer, keylen);
 358         memset(alignbuffer, 0, keylen);
 359         kfree(buffer);
 360         return ret;
 361 }
 362
 363 static int setkey(struct crypto_tfm *tfm, const u8 *key,
 364                   unsigned int keylen)
 365 {
 366         struct blkcipher_alg *cipher = &tfm->__crt_alg->cra_blkcipher;
 367         unsigned long alignmask = crypto_tfm_alg_alignmask(tfm);
 368
 369         if (keylen < cipher->min_keysize || keylen > cipher->max_keysize) {
 370                 tfm->crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
 371                 return -EINVAL;
 372         }
 373
 374         if ((unsigned long)key & alignmask)
 375                 return setkey_unaligned(tfm, key, keylen);
 376
 377         return cipher->setkey(tfm, key, keylen);
 378 }
 379
 380 static int async_setkey(struct crypto_ablkcipher *tfm, const u8 *key,
 381                         unsigned int keylen)
 382 {
 383         return setkey(crypto_ablkcipher_tfm(tfm), key, keylen);
 384 }
 385
 386 static int async_encrypt(struct ablkcipher_request *req)
 387 {
 388         struct crypto_tfm *tfm = req->base.tfm;
 389         struct blkcipher_alg *alg = &tfm->__crt_alg->cra_blkcipher;
 390         struct blkcipher_desc desc = {
 391                 .tfm = __crypto_blkcipher_cast(tfm),
 392                 .info = req->info,
 393                 .flags = req->base.flags,
 394         };
 395
 396
 397         return alg->encrypt(&desc, req->dst, req->src, req->nbytes);
 398 }
 399
 400 static int async_decrypt(struct ablkcipher_request *req)
 401 {
 402         struct crypto_tfm *tfm = req->base.tfm;
 403         struct blkcipher_alg *alg = &tfm->__crt_alg->cra_blkcipher;
 404         struct blkcipher_desc desc = {
 405                 .tfm = __crypto_blkcipher_cast(tfm),
 406                 .info = req->info,
 407                 .flags = req->base.flags,
 408         };
 409
 410         return alg->decrypt(&desc, req->dst, req->src, req->nbytes);
 411 }
 412
 413 static unsigned int crypto_blkcipher_ctxsize(struct crypto_alg *alg, u32 type,
 414                                              u32 mask)
 415 {
 416         struct blkcipher_alg *cipher = &alg->cra_blkcipher;
 417         unsigned int len = alg->cra_ctxsize;
 418
 419         type ^= CRYPTO_ALG_ASYNC;
 420         mask &= CRYPTO_ALG_ASYNC;
 421         if ((type & mask) && cipher->ivsize) {
 422                 len = ALIGN(len, (unsigned long)alg->cra_alignmask + 1);
 423                 len += cipher->ivsize;
 424         }
 425
 426         return len;
 427 }
 428
 429 static int crypto_init_blkcipher_ops_async(struct crypto_tfm *tfm)
 430 {
 431         struct ablkcipher_tfm *crt = &tfm->crt_ablkcipher;
 432         struct blkcipher_alg *alg = &tfm->__crt_alg->cra_blkcipher;
 433
 434         crt->setkey = async_setkey;
 435         crt->encrypt = async_encrypt;
 436         crt->decrypt = async_decrypt;
 437         crt->ivsize = alg->ivsize;
 438
 439         return 0;
 440 }
 441
 442 static int crypto_init_blkcipher_ops_sync(struct crypto_tfm *tfm)
 443 {
 444         struct blkcipher_tfm *crt = &tfm->crt_blkcipher;
 445         struct blkcipher_alg *alg = &tfm->__crt_alg->cra_blkcipher;
 446         unsigned long align = crypto_tfm_alg_alignmask(tfm) + 1;
 447         unsigned long addr;
 448
 449         crt->setkey = setkey;
 450         crt->encrypt = alg->encrypt;
 451         crt->decrypt = alg->decrypt;
 452
 453         addr = (unsigned long)crypto_tfm_ctx(tfm);
 454         addr = ALIGN(addr, align);
 455         addr += ALIGN(tfm->__crt_alg->cra_ctxsize, align);
 456         crt->iv = (void *)addr;
 457
 458         return 0;
 459 }
 460
 461 static int crypto_init_blkcipher_ops(struct crypto_tfm *tfm, u32 type, u32 mask)
 462 {
 463         struct blkcipher_alg *alg = &tfm->__crt_alg->cra_blkcipher;
 464
 465         if (alg->ivsize > PAGE_SIZE / 8)
 466                 return -EINVAL;
 467
 468         type ^= CRYPTO_ALG_ASYNC;
 469         mask &= CRYPTO_ALG_ASYNC;
 470         if (type & mask)
 471                 return crypto_init_blkcipher_ops_sync(tfm);
 472         else
 473                 return crypto_init_blkcipher_ops_async(tfm);
 474 }
 475
 476 static void crypto_blkcipher_show(struct seq_file *m, struct crypto_alg *alg)
 477         __attribute__ ((unused));
 478 static void crypto_blkcipher_show(struct seq_file *m, struct crypto_alg *alg)
 479 {
 480         seq_printf(m, "type         : blkcipher\n");
 481         seq_printf(m, "blocksize    : %u\n", alg->cra_blocksize);
 482         seq_printf(m, "min keysize  : %u\n", alg->cra_blkcipher.min_keysize);
 483         seq_printf(m, "max keysize  : %u\n", alg->cra_blkcipher.max_keysize);
 484         seq_printf(m, "ivsize       : %u\n", alg->cra_blkcipher.ivsize);
 485 }
 486
 487 const struct crypto_type crypto_blkcipher_type = {
 488         .ctxsize = crypto_blkcipher_ctxsize,
 489         .init = crypto_init_blkcipher_ops,
 490 #ifdef CONFIG_PROC_FS
 491         .show = crypto_blkcipher_show,
 492 #endif
 493 };
 494 EXPORT_SYMBOL_GPL(crypto_blkcipher_type);
 495
 496 MODULE_LICENSE("GPL");
 497 MODULE_DESCRIPTION("Generic block chaining cipher type");