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