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 <rsnel@cube.dyndns.org>
5 *
6 * Based on ecb.c
7 * Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au>
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/stds-p1619@listserv.ieee.org/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 {
33 struct crypto_cipher *child;
34 struct lrw_table_ctx table;
35 };
36
setbit128_bbe(void * b,int bit)37 static inline void setbit128_bbe(void *b, int bit)
38 {
39 __set_bit(bit ^ (0x80 -
40 #ifdef __BIG_ENDIAN
41 BITS_PER_LONG
42 #else
43 BITS_PER_BYTE
44 #endif
45 ), b);
46 }
47
lrw_init_table(struct lrw_table_ctx * ctx,const u8 * tweak)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)
54 gf128mul_free_64k(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 }
70 EXPORT_SYMBOL_GPL(lrw_init_table);
71
lrw_free_table(struct lrw_table_ctx * ctx)72 void lrw_free_table(struct lrw_table_ctx *ctx)
73 {
74 if (ctx->table)
75 gf128mul_free_64k(ctx->table);
76 }
77 EXPORT_SYMBOL_GPL(lrw_free_table);
78
setkey(struct crypto_tfm * parent,const u8 * key,unsigned int keylen)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) &
89 CRYPTO_TFM_REQ_MASK);
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) &
94 CRYPTO_TFM_RES_MASK);
95
96 return lrw_init_table(&ctx->table, tweak);
97 }
98
99 struct sinfo {
100 be128 t;
101 struct crypto_tfm *tfm;
102 void (*fn)(struct crypto_tfm *, u8 *, const u8 *);
103 };
104
inc(be128 * iv)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
lrw_round(struct sinfo * s,void * dst,const void * src)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 */
get_index128(be128 * block)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
crypt(struct blkcipher_desc * d,struct blkcipher_walk * w,struct priv * ctx,void (* fn)(struct crypto_tfm *,u8 *,const u8 *))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
encrypt(struct blkcipher_desc * desc,struct scatterlist * dst,struct scatterlist * src,unsigned int nbytes)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
decrypt(struct blkcipher_desc * desc,struct scatterlist * dst,struct scatterlist * src,unsigned int nbytes)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
lrw_crypt(struct blkcipher_desc * desc,struct scatterlist * sdst,struct scatterlist * ssrc,unsigned int nbytes,struct lrw_crypt_req * req)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 }
294 EXPORT_SYMBOL_GPL(lrw_crypt);
295
init_tfm(struct crypto_tfm * tfm)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) {
309 *flags |= CRYPTO_TFM_RES_BAD_BLOCK_LEN;
310 crypto_free_cipher(cipher);
311 return -EINVAL;
312 }
313
314 ctx->child = cipher;
315 return 0;
316 }
317
exit_tfm(struct crypto_tfm * tfm)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
alloc(struct rtattr ** tb)326 static struct crypto_instance *alloc(struct rtattr **tb)
327 {
328 struct crypto_instance *inst;
329 struct crypto_alg *alg;
330 int err;
331
332 err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER);
333 if (err)
334 return ERR_PTR(err);
335
336 alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER,
337 CRYPTO_ALG_TYPE_MASK);
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
free(struct crypto_instance * inst)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
crypto_module_init(void)388 static int __init crypto_module_init(void)
389 {
390 return crypto_register_template(&crypto_tmpl);
391 }
392
crypto_module_exit(void)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");
403 MODULE_ALIAS_CRYPTO("lrw");
404