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/kernel.h>
  20 #include <linux/module.h>
  21 #include <linux/scatterlist.h>
  22 #include <linux/seq_file.h>
  23 #include <linux/slab.h>
  24 #include <linux/string.h>
  25
  26 #include "internal.h"
  27 #include "scatterwalk.h"
  28
  29 enum {
  30         BLKCIPHER_WALK_PHYS = 1 << 0,
  31         BLKCIPHER_WALK_SLOW = 1 << 1,
  32         BLKCIPHER_WALK_COPY = 1 << 2,
  33         BLKCIPHER_WALK_DIFF = 1 << 3,
  34 };
  35
  36 static int blkcipher_walk_next(struct blkcipher_desc *desc,
  37                                struct blkcipher_walk *walk);
  38 static int blkcipher_walk_first(struct blkcipher_desc *desc,
  39                                 struct blkcipher_walk *walk);
  40
  41 static inline void blkcipher_map_src(struct blkcipher_walk *walk)
  42 {
  43         walk->src.virt.addr = scatterwalk_map(&walk->in, 0);
  44 }
  45
  46 static inline void blkcipher_map_dst(struct blkcipher_walk *walk)
  47 {
  48         walk->dst.virt.addr = scatterwalk_map(&walk->out, 1);
  49 }
  50
  51 static inline void blkcipher_unmap_src(struct blkcipher_walk *walk)
  52 {
  53         scatterwalk_unmap(walk->src.virt.addr, 0);
  54 }
  55
  56 static inline void blkcipher_unmap_dst(struct blkcipher_walk *walk)
  57 {
  58         scatterwalk_unmap(walk->dst.virt.addr, 1);
  59 }
  60
  61 static inline u8 *blkcipher_get_spot(u8 *start, unsigned int len)
  62 {
  63         if (offset_in_page(start + len) < len)
  64                 return (u8 *)((unsigned long)(start + len) & PAGE_MASK);
  65         return start;
  66 }
  67
  68 static inline unsigned int blkcipher_done_slow(struct crypto_blkcipher *tfm,
  69                                                struct blkcipher_walk *walk,
  70                                                unsigned int bsize)
  71 {
  72         u8 *addr;
  73         unsigned int alignmask = crypto_blkcipher_alignmask(tfm);
  74
  75         addr = (u8 *)ALIGN((unsigned long)walk->buffer, alignmask + 1);
  76         addr = blkcipher_get_spot(addr, bsize);
  77         scatterwalk_copychunks(addr, &walk->out, bsize, 1);
  78         return bsize;
  79 }
  80
  81 static inline unsigned int blkcipher_done_fast(struct blkcipher_walk *walk,
  82                                                unsigned int n)
  83 {
  84         n = walk->nbytes - n;
  85
  86         if (walk->flags & BLKCIPHER_WALK_COPY) {
  87                 blkcipher_map_dst(walk);
  88                 memcpy(walk->dst.virt.addr, walk->page, n);
  89                 blkcipher_unmap_dst(walk);
  90         } else if (!(walk->flags & BLKCIPHER_WALK_PHYS)) {
  91                 blkcipher_unmap_src(walk);
  92                 if (walk->flags & BLKCIPHER_WALK_DIFF)
  93                         blkcipher_unmap_dst(walk);
  94         }
  95
  96         scatterwalk_advance(&walk->in, n);
  97         scatterwalk_advance(&walk->out, n);
  98
  99         return n;
 100 }
 101
 102 int blkcipher_walk_done(struct blkcipher_desc *desc,
 103                         struct blkcipher_walk *walk, int err)
 104 {
 105         struct crypto_blkcipher *tfm = desc->tfm;
 106         unsigned int nbytes = 0;
 107
 108         if (likely(err >= 0)) {
 109                 unsigned int bsize = crypto_blkcipher_blocksize(tfm);
 110                 unsigned int n;
 111
 112                 if (likely(!(walk->flags & BLKCIPHER_WALK_SLOW)))
 113                         n = blkcipher_done_fast(walk, err);
 114                 else
 115                         n = blkcipher_done_slow(tfm, walk, bsize);
 116
 117                 nbytes = walk->total - n;
 118                 err = 0;
 119         }
 120
 121         scatterwalk_done(&walk->in, 0, nbytes);
 122         scatterwalk_done(&walk->out, 1, nbytes);
 123
 124         walk->total = nbytes;
 125         walk->nbytes = nbytes;
 126
 127         if (nbytes) {
 128                 crypto_yield(desc->flags);
 129                 return blkcipher_walk_next(desc, walk);
 130         }
 131
 132         if (walk->iv != desc->info)
 133                 memcpy(desc->info, walk->iv, crypto_blkcipher_ivsize(tfm));
 134         if (walk->buffer != walk->page)
 135                 kfree(walk->buffer);
 136         if (walk->page)
 137                 free_page((unsigned long)walk->page);
 138
 139         return err;
 140 }
 141 EXPORT_SYMBOL_GPL(blkcipher_walk_done);
 142
 143 static inline int blkcipher_next_slow(struct blkcipher_desc *desc,
 144                                       struct blkcipher_walk *walk,
 145                                       unsigned int bsize,
 146                                       unsigned int alignmask)
 147 {
 148         unsigned int n;
 149
 150         if (walk->buffer)
 151                 goto ok;
 152
 153         walk->buffer = walk->page;
 154         if (walk->buffer)
 155                 goto ok;
 156
 157         n = bsize * 2 + (alignmask & ~(crypto_tfm_ctx_alignment() - 1));
 158         walk->buffer = kmalloc(n, GFP_ATOMIC);
 159         if (!walk->buffer)
 160                 return blkcipher_walk_done(desc, walk, -ENOMEM);
 161
 162 ok:
 163         walk->dst.virt.addr = (u8 *)ALIGN((unsigned long)walk->buffer,
 164                                           alignmask + 1);
 165         walk->dst.virt.addr = blkcipher_get_spot(walk->dst.virt.addr, bsize);
 166         walk->src.virt.addr = blkcipher_get_spot(walk->dst.virt.addr + bsize,
 167                                                  bsize);
 168
 169         scatterwalk_copychunks(walk->src.virt.addr, &walk->in, bsize, 0);
 170
 171         walk->nbytes = bsize;
 172         walk->flags |= BLKCIPHER_WALK_SLOW;
 173
 174         return 0;
 175 }
 176
 177 static inline int blkcipher_next_copy(struct blkcipher_walk *walk)
 178 {
 179         u8 *tmp = walk->page;
 180
 181         blkcipher_map_src(walk);
 182         memcpy(tmp, walk->src.virt.addr, walk->nbytes);
 183         blkcipher_unmap_src(walk);
 184
 185         walk->src.virt.addr = tmp;
 186         walk->dst.virt.addr = tmp;
 187
 188         return 0;
 189 }
 190
 191 static inline int blkcipher_next_fast(struct blkcipher_desc *desc,
 192                                       struct blkcipher_walk *walk)
 193 {
 194         unsigned long diff;
 195
 196         walk->src.phys.page = scatterwalk_page(&walk->in);
 197         walk->src.phys.offset = offset_in_page(walk->in.offset);
 198         walk->dst.phys.page = scatterwalk_page(&walk->out);
 199         walk->dst.phys.offset = offset_in_page(walk->out.offset);
 200
 201         if (walk->flags & BLKCIPHER_WALK_PHYS)
 202                 return 0;
 203
 204         diff = walk->src.phys.offset - walk->dst.phys.offset;
 205         diff |= walk->src.virt.page - walk->dst.virt.page;
 206
 207         blkcipher_map_src(walk);
 208         walk->dst.virt.addr = walk->src.virt.addr;
 209
 210         if (diff) {
 211                 walk->flags |= BLKCIPHER_WALK_DIFF;
 212                 blkcipher_map_dst(walk);
 213         }
 214
 215         return 0;
 216 }
 217
 218 static int blkcipher_walk_next(struct blkcipher_desc *desc,
 219                                struct blkcipher_walk *walk)
 220 {
 221         struct crypto_blkcipher *tfm = desc->tfm;
 222         unsigned int alignmask = crypto_blkcipher_alignmask(tfm);
 223         unsigned int bsize = crypto_blkcipher_blocksize(tfm);
 224         unsigned int n;
 225         int err;
 226
 227         n = walk->total;
 228         if (unlikely(n < bsize)) {
 229                 desc->flags |= CRYPTO_TFM_RES_BAD_BLOCK_LEN;
 230                 return blkcipher_walk_done(desc, walk, -EINVAL);
 231         }
 232
 233         walk->flags &= ~(BLKCIPHER_WALK_SLOW | BLKCIPHER_WALK_COPY |
 234                          BLKCIPHER_WALK_DIFF);
 235         if (!scatterwalk_aligned(&walk->in, alignmask) ||
 236             !scatterwalk_aligned(&walk->out, alignmask)) {
 237                 walk->flags |= BLKCIPHER_WALK_COPY;
 238                 if (!walk->page) {
 239                         walk->page = (void *)__get_free_page(GFP_ATOMIC);
 240                         if (!walk->page)
 241                                 n = 0;
 242                 }
 243         }
 244
 245         n = scatterwalk_clamp(&walk->in, n);
 246         n = scatterwalk_clamp(&walk->out, n);
 247
 248         if (unlikely(n < bsize)) {
 249                 err = blkcipher_next_slow(desc, walk, bsize, alignmask);
 250                 goto set_phys_lowmem;
 251         }
 252
 253         walk->nbytes = n;
 254         if (walk->flags & BLKCIPHER_WALK_COPY) {
 255                 err = blkcipher_next_copy(walk);
 256                 goto set_phys_lowmem;
 257         }
 258
 259         return blkcipher_next_fast(desc, walk);
 260
 261 set_phys_lowmem:
 262         if (walk->flags & BLKCIPHER_WALK_PHYS) {
 263                 walk->src.phys.page = virt_to_page(walk->src.virt.addr);
 264                 walk->dst.phys.page = virt_to_page(walk->dst.virt.addr);
 265                 walk->src.phys.offset &= PAGE_SIZE - 1;
 266                 walk->dst.phys.offset &= PAGE_SIZE - 1;
 267         }
 268         return err;
 269 }
 270
 271 static inline int blkcipher_copy_iv(struct blkcipher_walk *walk,
 272                                     struct crypto_blkcipher *tfm,
 273                                     unsigned int alignmask)
 274 {
 275         unsigned bs = crypto_blkcipher_blocksize(tfm);
 276         unsigned int ivsize = crypto_blkcipher_ivsize(tfm);
 277         unsigned int size = bs * 2 + ivsize + max(bs, ivsize) - (alignmask + 1);
 278         u8 *iv;
 279
 280         size += alignmask & ~(crypto_tfm_ctx_alignment() - 1);
 281         walk->buffer = kmalloc(size, GFP_ATOMIC);
 282         if (!walk->buffer)
 283                 return -ENOMEM;
 284
 285         iv = (u8 *)ALIGN((unsigned long)walk->buffer, alignmask + 1);
 286         iv = blkcipher_get_spot(iv, bs) + bs;
 287         iv = blkcipher_get_spot(iv, bs) + bs;
 288         iv = blkcipher_get_spot(iv, ivsize);
 289
 290         walk->iv = memcpy(iv, walk->iv, ivsize);
 291         return 0;
 292 }
 293
 294 int blkcipher_walk_virt(struct blkcipher_desc *desc,
 295                         struct blkcipher_walk *walk)
 296 {
 297         walk->flags &= ~BLKCIPHER_WALK_PHYS;
 298         return blkcipher_walk_first(desc, walk);
 299 }
 300 EXPORT_SYMBOL_GPL(blkcipher_walk_virt);
 301
 302 int blkcipher_walk_phys(struct blkcipher_desc *desc,
 303                         struct blkcipher_walk *walk)
 304 {
 305         walk->flags |= BLKCIPHER_WALK_PHYS;
 306         return blkcipher_walk_first(desc, walk);
 307 }
 308 EXPORT_SYMBOL_GPL(blkcipher_walk_phys);
 309
 310 static int blkcipher_walk_first(struct blkcipher_desc *desc,
 311                                 struct blkcipher_walk *walk)
 312 {
 313         struct crypto_blkcipher *tfm = desc->tfm;
 314         unsigned int alignmask = crypto_blkcipher_alignmask(tfm);
 315
 316         walk->nbytes = walk->total;
 317         if (unlikely(!walk->total))
 318                 return 0;
 319
 320         walk->buffer = NULL;
 321         walk->iv = desc->info;
 322         if (unlikely(((unsigned long)walk->iv & alignmask))) {
 323                 int err = blkcipher_copy_iv(walk, tfm, alignmask);
 324                 if (err)
 325                         return err;
 326         }
 327
 328         scatterwalk_start(&walk->in, walk->in.sg);
 329         scatterwalk_start(&walk->out, walk->out.sg);
 330         walk->page = NULL;
 331
 332         return blkcipher_walk_next(desc, walk);
 333 }
 334
 335 static int setkey(struct crypto_tfm *tfm, const u8 *key,
 336                   unsigned int keylen)
 337 {
 338         struct blkcipher_alg *cipher = &tfm->__crt_alg->cra_blkcipher;
 339
 340         if (keylen < cipher->min_keysize || keylen > cipher->max_keysize) {
 341                 tfm->crt_flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
 342                 return -EINVAL;
 343         }
 344
 345         return cipher->setkey(tfm, key, keylen);
 346 }
 347
 348 static unsigned int crypto_blkcipher_ctxsize(struct crypto_alg *alg)
 349 {
 350         struct blkcipher_alg *cipher = &alg->cra_blkcipher;
 351         unsigned int len = alg->cra_ctxsize;
 352
 353         if (cipher->ivsize) {
 354                 len = ALIGN(len, (unsigned long)alg->cra_alignmask + 1);
 355                 len += cipher->ivsize;
 356         }
 357
 358         return len;
 359 }
 360
 361 static int crypto_init_blkcipher_ops(struct crypto_tfm *tfm)
 362 {
 363         struct blkcipher_tfm *crt = &tfm->crt_blkcipher;
 364         struct blkcipher_alg *alg = &tfm->__crt_alg->cra_blkcipher;
 365         unsigned long align = crypto_tfm_alg_alignmask(tfm) + 1;
 366         unsigned long addr;
 367
 368         if (alg->ivsize > PAGE_SIZE / 8)
 369                 return -EINVAL;
 370
 371         crt->setkey = setkey;
 372         crt->encrypt = alg->encrypt;
 373         crt->decrypt = alg->decrypt;
 374
 375         addr = (unsigned long)crypto_tfm_ctx(tfm);
 376         addr = ALIGN(addr, align);
 377         addr += ALIGN(tfm->__crt_alg->cra_ctxsize, align);
 378         crt->iv = (void *)addr;
 379
 380         return 0;
 381 }
 382
 383 static void crypto_blkcipher_show(struct seq_file *m, struct crypto_alg *alg)
 384         __attribute_used__;
 385 static void crypto_blkcipher_show(struct seq_file *m, struct crypto_alg *alg)
 386 {
 387         seq_printf(m, "type         : blkcipher\n");
 388         seq_printf(m, "blocksize    : %u\n", alg->cra_blocksize);
 389         seq_printf(m, "min keysize  : %u\n", alg->cra_blkcipher.min_keysize);
 390         seq_printf(m, "max keysize  : %u\n", alg->cra_blkcipher.max_keysize);
 391         seq_printf(m, "ivsize       : %u\n", alg->cra_blkcipher.ivsize);
 392 }
 393
 394 const struct crypto_type crypto_blkcipher_type = {
 395         .ctxsize = crypto_blkcipher_ctxsize,
 396         .init = crypto_init_blkcipher_ops,
 397 #ifdef CONFIG_PROC_FS
 398         .show = crypto_blkcipher_show,
 399 #endif
 400 };
 401 EXPORT_SYMBOL_GPL(crypto_blkcipher_type);
 402
 403 MODULE_LICENSE("GPL");
 404 MODULE_DESCRIPTION("Generic block chaining cipher type");