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lrw.c
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1 /* LRW: as defined by Cyril Guyot in
2  * http://grouper.ieee.org/groups/1619/email/pdf00017.pdf
3  *
4  * Copyright (c) 2006 Rik Snel <[email protected]>
5  *
6  * Based on ecb.c
7  * Copyright (c) 2006 Herbert Xu <[email protected]>
8  *
9  * This program is free software; you can redistribute it and/or modify it
10  * under the terms of the GNU General Public License as published by the Free
11  * Software Foundation; either version 2 of the License, or (at your option)
12  * any later version.
13  */
14 /* This implementation is checked against the test vectors in the above
15  * document and by a test vector provided by Ken Buchanan at
16  * http://www.mail-archive.com/[email protected]/msg00173.html
17  *
18  * The test vectors are included in the testing module tcrypt.[ch] */
19 
20 #include <crypto/algapi.h>
21 #include <linux/err.h>
22 #include <linux/init.h>
23 #include <linux/kernel.h>
24 #include <linux/module.h>
25 #include <linux/scatterlist.h>
26 #include <linux/slab.h>
27 
28 #include <crypto/b128ops.h>
29 #include <crypto/gf128mul.h>
30 #include <crypto/lrw.h>
31 
32 struct priv {
35 };
36 
37 static inline void setbit128_bbe(void *b, int bit)
38 {
39  __set_bit(bit ^ (0x80 -
40 #ifdef __BIG_ENDIAN
42 #else
44 #endif
45  ), b);
46 }
47 
48 int lrw_init_table(struct lrw_table_ctx *ctx, const u8 *tweak)
49 {
50  be128 tmp = { 0 };
51  int i;
52 
53  if (ctx->table)
55 
56  /* initialize multiplication table for Key2 */
57  ctx->table = gf128mul_init_64k_bbe((be128 *)tweak);
58  if (!ctx->table)
59  return -ENOMEM;
60 
61  /* initialize optimization table */
62  for (i = 0; i < 128; i++) {
63  setbit128_bbe(&tmp, i);
64  ctx->mulinc[i] = tmp;
65  gf128mul_64k_bbe(&ctx->mulinc[i], ctx->table);
66  }
67 
68  return 0;
69 }
71 
73 {
74  if (ctx->table)
76 }
78 
79 static int setkey(struct crypto_tfm *parent, const u8 *key,
80  unsigned int keylen)
81 {
82  struct priv *ctx = crypto_tfm_ctx(parent);
83  struct crypto_cipher *child = ctx->child;
84  int err, bsize = LRW_BLOCK_SIZE;
85  const u8 *tweak = key + keylen - bsize;
86 
87  crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
88  crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &
90  err = crypto_cipher_setkey(child, key, keylen - bsize);
91  if (err)
92  return err;
93  crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &
95 
96  return lrw_init_table(&ctx->table, tweak);
97 }
98 
99 struct sinfo {
101  struct crypto_tfm *tfm;
102  void (*fn)(struct crypto_tfm *, u8 *, const u8 *);
103 };
104 
105 static inline void inc(be128 *iv)
106 {
107  be64_add_cpu(&iv->b, 1);
108  if (!iv->b)
109  be64_add_cpu(&iv->a, 1);
110 }
111 
112 static inline void lrw_round(struct sinfo *s, void *dst, const void *src)
113 {
114  be128_xor(dst, &s->t, src); /* PP <- T xor P */
115  s->fn(s->tfm, dst, dst); /* CC <- E(Key2,PP) */
116  be128_xor(dst, dst, &s->t); /* C <- T xor CC */
117 }
118 
119 /* this returns the number of consequative 1 bits starting
120  * from the right, get_index128(00 00 00 00 00 00 ... 00 00 10 FB) = 2 */
121 static inline int get_index128(be128 *block)
122 {
123  int x;
124  __be32 *p = (__be32 *) block;
125 
126  for (p += 3, x = 0; x < 128; p--, x += 32) {
127  u32 val = be32_to_cpup(p);
128 
129  if (!~val)
130  continue;
131 
132  return x + ffz(val);
133  }
134 
135  return x;
136 }
137 
138 static int crypt(struct blkcipher_desc *d,
139  struct blkcipher_walk *w, struct priv *ctx,
140  void (*fn)(struct crypto_tfm *, u8 *, const u8 *))
141 {
142  int err;
143  unsigned int avail;
144  const int bs = LRW_BLOCK_SIZE;
145  struct sinfo s = {
146  .tfm = crypto_cipher_tfm(ctx->child),
147  .fn = fn
148  };
149  be128 *iv;
150  u8 *wsrc;
151  u8 *wdst;
152 
153  err = blkcipher_walk_virt(d, w);
154  if (!(avail = w->nbytes))
155  return err;
156 
157  wsrc = w->src.virt.addr;
158  wdst = w->dst.virt.addr;
159 
160  /* calculate first value of T */
161  iv = (be128 *)w->iv;
162  s.t = *iv;
163 
164  /* T <- I*Key2 */
165  gf128mul_64k_bbe(&s.t, ctx->table.table);
166 
167  goto first;
168 
169  for (;;) {
170  do {
171  /* T <- I*Key2, using the optimization
172  * discussed in the specification */
173  be128_xor(&s.t, &s.t,
174  &ctx->table.mulinc[get_index128(iv)]);
175  inc(iv);
176 
177 first:
178  lrw_round(&s, wdst, wsrc);
179 
180  wsrc += bs;
181  wdst += bs;
182  } while ((avail -= bs) >= bs);
183 
184  err = blkcipher_walk_done(d, w, avail);
185  if (!(avail = w->nbytes))
186  break;
187 
188  wsrc = w->src.virt.addr;
189  wdst = w->dst.virt.addr;
190  }
191 
192  return err;
193 }
194 
195 static int encrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
196  struct scatterlist *src, unsigned int nbytes)
197 {
198  struct priv *ctx = crypto_blkcipher_ctx(desc->tfm);
199  struct blkcipher_walk w;
200 
201  blkcipher_walk_init(&w, dst, src, nbytes);
202  return crypt(desc, &w, ctx,
203  crypto_cipher_alg(ctx->child)->cia_encrypt);
204 }
205 
206 static int decrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
207  struct scatterlist *src, unsigned int nbytes)
208 {
209  struct priv *ctx = crypto_blkcipher_ctx(desc->tfm);
210  struct blkcipher_walk w;
211 
212  blkcipher_walk_init(&w, dst, src, nbytes);
213  return crypt(desc, &w, ctx,
214  crypto_cipher_alg(ctx->child)->cia_decrypt);
215 }
216 
217 int lrw_crypt(struct blkcipher_desc *desc, struct scatterlist *sdst,
218  struct scatterlist *ssrc, unsigned int nbytes,
219  struct lrw_crypt_req *req)
220 {
221  const unsigned int bsize = LRW_BLOCK_SIZE;
222  const unsigned int max_blks = req->tbuflen / bsize;
223  struct lrw_table_ctx *ctx = req->table_ctx;
224  struct blkcipher_walk walk;
225  unsigned int nblocks;
226  be128 *iv, *src, *dst, *t;
227  be128 *t_buf = req->tbuf;
228  int err, i;
229 
230  BUG_ON(max_blks < 1);
231 
232  blkcipher_walk_init(&walk, sdst, ssrc, nbytes);
233 
234  err = blkcipher_walk_virt(desc, &walk);
235  nbytes = walk.nbytes;
236  if (!nbytes)
237  return err;
238 
239  nblocks = min(walk.nbytes / bsize, max_blks);
240  src = (be128 *)walk.src.virt.addr;
241  dst = (be128 *)walk.dst.virt.addr;
242 
243  /* calculate first value of T */
244  iv = (be128 *)walk.iv;
245  t_buf[0] = *iv;
246 
247  /* T <- I*Key2 */
248  gf128mul_64k_bbe(&t_buf[0], ctx->table);
249 
250  i = 0;
251  goto first;
252 
253  for (;;) {
254  do {
255  for (i = 0; i < nblocks; i++) {
256  /* T <- I*Key2, using the optimization
257  * discussed in the specification */
258  be128_xor(&t_buf[i], t,
259  &ctx->mulinc[get_index128(iv)]);
260  inc(iv);
261 first:
262  t = &t_buf[i];
263 
264  /* PP <- T xor P */
265  be128_xor(dst + i, t, src + i);
266  }
267 
268  /* CC <- E(Key2,PP) */
269  req->crypt_fn(req->crypt_ctx, (u8 *)dst,
270  nblocks * bsize);
271 
272  /* C <- T xor CC */
273  for (i = 0; i < nblocks; i++)
274  be128_xor(dst + i, dst + i, &t_buf[i]);
275 
276  src += nblocks;
277  dst += nblocks;
278  nbytes -= nblocks * bsize;
279  nblocks = min(nbytes / bsize, max_blks);
280  } while (nblocks > 0);
281 
282  err = blkcipher_walk_done(desc, &walk, nbytes);
283  nbytes = walk.nbytes;
284  if (!nbytes)
285  break;
286 
287  nblocks = min(nbytes / bsize, max_blks);
288  src = (be128 *)walk.src.virt.addr;
289  dst = (be128 *)walk.dst.virt.addr;
290  }
291 
292  return err;
293 }
295 
296 static int init_tfm(struct crypto_tfm *tfm)
297 {
298  struct crypto_cipher *cipher;
299  struct crypto_instance *inst = (void *)tfm->__crt_alg;
300  struct crypto_spawn *spawn = crypto_instance_ctx(inst);
301  struct priv *ctx = crypto_tfm_ctx(tfm);
302  u32 *flags = &tfm->crt_flags;
303 
304  cipher = crypto_spawn_cipher(spawn);
305  if (IS_ERR(cipher))
306  return PTR_ERR(cipher);
307 
308  if (crypto_cipher_blocksize(cipher) != LRW_BLOCK_SIZE) {
310  crypto_free_cipher(cipher);
311  return -EINVAL;
312  }
313 
314  ctx->child = cipher;
315  return 0;
316 }
317 
318 static void exit_tfm(struct crypto_tfm *tfm)
319 {
320  struct priv *ctx = crypto_tfm_ctx(tfm);
321 
322  lrw_free_table(&ctx->table);
323  crypto_free_cipher(ctx->child);
324 }
325 
326 static struct crypto_instance *alloc(struct rtattr **tb)
327 {
328  struct crypto_instance *inst;
329  struct crypto_alg *alg;
330  int err;
331 
333  if (err)
334  return ERR_PTR(err);
335 
336  alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER,
338  if (IS_ERR(alg))
339  return ERR_CAST(alg);
340 
341  inst = crypto_alloc_instance("lrw", alg);
342  if (IS_ERR(inst))
343  goto out_put_alg;
344 
345  inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER;
346  inst->alg.cra_priority = alg->cra_priority;
347  inst->alg.cra_blocksize = alg->cra_blocksize;
348 
349  if (alg->cra_alignmask < 7) inst->alg.cra_alignmask = 7;
350  else inst->alg.cra_alignmask = alg->cra_alignmask;
351  inst->alg.cra_type = &crypto_blkcipher_type;
352 
353  if (!(alg->cra_blocksize % 4))
354  inst->alg.cra_alignmask |= 3;
355  inst->alg.cra_blkcipher.ivsize = alg->cra_blocksize;
356  inst->alg.cra_blkcipher.min_keysize =
357  alg->cra_cipher.cia_min_keysize + alg->cra_blocksize;
358  inst->alg.cra_blkcipher.max_keysize =
359  alg->cra_cipher.cia_max_keysize + alg->cra_blocksize;
360 
361  inst->alg.cra_ctxsize = sizeof(struct priv);
362 
363  inst->alg.cra_init = init_tfm;
364  inst->alg.cra_exit = exit_tfm;
365 
366  inst->alg.cra_blkcipher.setkey = setkey;
367  inst->alg.cra_blkcipher.encrypt = encrypt;
368  inst->alg.cra_blkcipher.decrypt = decrypt;
369 
370 out_put_alg:
371  crypto_mod_put(alg);
372  return inst;
373 }
374 
375 static void free(struct crypto_instance *inst)
376 {
377  crypto_drop_spawn(crypto_instance_ctx(inst));
378  kfree(inst);
379 }
380 
381 static struct crypto_template crypto_tmpl = {
382  .name = "lrw",
383  .alloc = alloc,
384  .free = free,
385  .module = THIS_MODULE,
386 };
387 
388 static int __init crypto_module_init(void)
389 {
390  return crypto_register_template(&crypto_tmpl);
391 }
392 
393 static void __exit crypto_module_exit(void)
394 {
395  crypto_unregister_template(&crypto_tmpl);
396 }
397 
398 module_init(crypto_module_init);
399 module_exit(crypto_module_exit);
400 
401 MODULE_LICENSE("GPL");
402 MODULE_DESCRIPTION("LRW block cipher mode");