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TOMOYO Linux Cross Reference
Linux/crypto/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 <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/internal/skcipher.h>
 21 #include <crypto/scatterwalk.h>
 22 #include <linux/err.h>
 23 #include <linux/init.h>
 24 #include <linux/kernel.h>
 25 #include <linux/module.h>
 26 #include <linux/scatterlist.h>
 27 #include <linux/slab.h>
 28 
 29 #include <crypto/b128ops.h>
 30 #include <crypto/gf128mul.h>
 31 
 32 #define LRW_BUFFER_SIZE 128u
 33 
 34 #define LRW_BLOCK_SIZE 16
 35 
 36 struct priv {
 37         struct crypto_skcipher *child;
 38 
 39         /*
 40          * optimizes multiplying a random (non incrementing, as at the
 41          * start of a new sector) value with key2, we could also have
 42          * used 4k optimization tables or no optimization at all. In the
 43          * latter case we would have to store key2 here
 44          */
 45         struct gf128mul_64k *table;
 46 
 47         /*
 48          * stores:
 49          *  key2*{ 0,0,...0,0,0,0,1 }, key2*{ 0,0,...0,0,0,1,1 },
 50          *  key2*{ 0,0,...0,0,1,1,1 }, key2*{ 0,0,...0,1,1,1,1 }
 51          *  key2*{ 0,0,...1,1,1,1,1 }, etc
 52          * needed for optimized multiplication of incrementing values
 53          * with key2
 54          */
 55         be128 mulinc[128];
 56 };
 57 
 58 struct rctx {
 59         be128 buf[LRW_BUFFER_SIZE / sizeof(be128)];
 60 
 61         be128 t;
 62 
 63         be128 *ext;
 64 
 65         struct scatterlist srcbuf[2];
 66         struct scatterlist dstbuf[2];
 67         struct scatterlist *src;
 68         struct scatterlist *dst;
 69 
 70         unsigned int left;
 71 
 72         struct skcipher_request subreq;
 73 };
 74 
 75 static inline void setbit128_bbe(void *b, int bit)
 76 {
 77         __set_bit(bit ^ (0x80 -
 78 #ifdef __BIG_ENDIAN
 79                          BITS_PER_LONG
 80 #else
 81                          BITS_PER_BYTE
 82 #endif
 83                         ), b);
 84 }
 85 
 86 static int setkey(struct crypto_skcipher *parent, const u8 *key,
 87                   unsigned int keylen)
 88 {
 89         struct priv *ctx = crypto_skcipher_ctx(parent);
 90         struct crypto_skcipher *child = ctx->child;
 91         int err, bsize = LRW_BLOCK_SIZE;
 92         const u8 *tweak = key + keylen - bsize;
 93         be128 tmp = { 0 };
 94         int i;
 95 
 96         crypto_skcipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
 97         crypto_skcipher_set_flags(child, crypto_skcipher_get_flags(parent) &
 98                                          CRYPTO_TFM_REQ_MASK);
 99         err = crypto_skcipher_setkey(child, key, keylen - bsize);
100         crypto_skcipher_set_flags(parent, crypto_skcipher_get_flags(child) &
101                                           CRYPTO_TFM_RES_MASK);
102         if (err)
103                 return err;
104 
105         if (ctx->table)
106                 gf128mul_free_64k(ctx->table);
107 
108         /* initialize multiplication table for Key2 */
109         ctx->table = gf128mul_init_64k_bbe((be128 *)tweak);
110         if (!ctx->table)
111                 return -ENOMEM;
112 
113         /* initialize optimization table */
114         for (i = 0; i < 128; i++) {
115                 setbit128_bbe(&tmp, i);
116                 ctx->mulinc[i] = tmp;
117                 gf128mul_64k_bbe(&ctx->mulinc[i], ctx->table);
118         }
119 
120         return 0;
121 }
122 
123 static inline void inc(be128 *iv)
124 {
125         be64_add_cpu(&iv->b, 1);
126         if (!iv->b)
127                 be64_add_cpu(&iv->a, 1);
128 }
129 
130 /* this returns the number of consequative 1 bits starting
131  * from the right, get_index128(00 00 00 00 00 00 ... 00 00 10 FB) = 2 */
132 static inline int get_index128(be128 *block)
133 {
134         int x;
135         __be32 *p = (__be32 *) block;
136 
137         for (p += 3, x = 0; x < 128; p--, x += 32) {
138                 u32 val = be32_to_cpup(p);
139 
140                 if (!~val)
141                         continue;
142 
143                 return x + ffz(val);
144         }
145 
146         /*
147          * If we get here, then x == 128 and we are incrementing the counter
148          * from all ones to all zeros. This means we must return index 127, i.e.
149          * the one corresponding to key2*{ 1,...,1 }.
150          */
151         return 127;
152 }
153 
154 static int post_crypt(struct skcipher_request *req)
155 {
156         struct rctx *rctx = skcipher_request_ctx(req);
157         be128 *buf = rctx->ext ?: rctx->buf;
158         struct skcipher_request *subreq;
159         const int bs = LRW_BLOCK_SIZE;
160         struct skcipher_walk w;
161         struct scatterlist *sg;
162         unsigned offset;
163         int err;
164 
165         subreq = &rctx->subreq;
166         err = skcipher_walk_virt(&w, subreq, false);
167 
168         while (w.nbytes) {
169                 unsigned int avail = w.nbytes;
170                 be128 *wdst;
171 
172                 wdst = w.dst.virt.addr;
173 
174                 do {
175                         be128_xor(wdst, buf++, wdst);
176                         wdst++;
177                 } while ((avail -= bs) >= bs);
178 
179                 err = skcipher_walk_done(&w, avail);
180         }
181 
182         rctx->left -= subreq->cryptlen;
183 
184         if (err || !rctx->left)
185                 goto out;
186 
187         rctx->dst = rctx->dstbuf;
188 
189         scatterwalk_done(&w.out, 0, 1);
190         sg = w.out.sg;
191         offset = w.out.offset;
192 
193         if (rctx->dst != sg) {
194                 rctx->dst[0] = *sg;
195                 sg_unmark_end(rctx->dst);
196                 scatterwalk_crypto_chain(rctx->dst, sg_next(sg), 0, 2);
197         }
198         rctx->dst[0].length -= offset - sg->offset;
199         rctx->dst[0].offset = offset;
200 
201 out:
202         return err;
203 }
204 
205 static int pre_crypt(struct skcipher_request *req)
206 {
207         struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
208         struct rctx *rctx = skcipher_request_ctx(req);
209         struct priv *ctx = crypto_skcipher_ctx(tfm);
210         be128 *buf = rctx->ext ?: rctx->buf;
211         struct skcipher_request *subreq;
212         const int bs = LRW_BLOCK_SIZE;
213         struct skcipher_walk w;
214         struct scatterlist *sg;
215         unsigned cryptlen;
216         unsigned offset;
217         be128 *iv;
218         bool more;
219         int err;
220 
221         subreq = &rctx->subreq;
222         skcipher_request_set_tfm(subreq, tfm);
223 
224         cryptlen = subreq->cryptlen;
225         more = rctx->left > cryptlen;
226         if (!more)
227                 cryptlen = rctx->left;
228 
229         skcipher_request_set_crypt(subreq, rctx->src, rctx->dst,
230                                    cryptlen, req->iv);
231 
232         err = skcipher_walk_virt(&w, subreq, false);
233         iv = w.iv;
234 
235         while (w.nbytes) {
236                 unsigned int avail = w.nbytes;
237                 be128 *wsrc;
238                 be128 *wdst;
239 
240                 wsrc = w.src.virt.addr;
241                 wdst = w.dst.virt.addr;
242 
243                 do {
244                         *buf++ = rctx->t;
245                         be128_xor(wdst++, &rctx->t, wsrc++);
246 
247                         /* T <- I*Key2, using the optimization
248                          * discussed in the specification */
249                         be128_xor(&rctx->t, &rctx->t,
250                                   &ctx->mulinc[get_index128(iv)]);
251                         inc(iv);
252                 } while ((avail -= bs) >= bs);
253 
254                 err = skcipher_walk_done(&w, avail);
255         }
256 
257         skcipher_request_set_tfm(subreq, ctx->child);
258         skcipher_request_set_crypt(subreq, rctx->dst, rctx->dst,
259                                    cryptlen, NULL);
260 
261         if (err || !more)
262                 goto out;
263 
264         rctx->src = rctx->srcbuf;
265 
266         scatterwalk_done(&w.in, 0, 1);
267         sg = w.in.sg;
268         offset = w.in.offset;
269 
270         if (rctx->src != sg) {
271                 rctx->src[0] = *sg;
272                 sg_unmark_end(rctx->src);
273                 scatterwalk_crypto_chain(rctx->src, sg_next(sg), 0, 2);
274         }
275         rctx->src[0].length -= offset - sg->offset;
276         rctx->src[0].offset = offset;
277 
278 out:
279         return err;
280 }
281 
282 static int init_crypt(struct skcipher_request *req, crypto_completion_t done)
283 {
284         struct priv *ctx = crypto_skcipher_ctx(crypto_skcipher_reqtfm(req));
285         struct rctx *rctx = skcipher_request_ctx(req);
286         struct skcipher_request *subreq;
287         gfp_t gfp;
288 
289         subreq = &rctx->subreq;
290         skcipher_request_set_callback(subreq, req->base.flags, done, req);
291 
292         gfp = req->base.flags & CRYPTO_TFM_REQ_MAY_SLEEP ? GFP_KERNEL :
293                                                            GFP_ATOMIC;
294         rctx->ext = NULL;
295 
296         subreq->cryptlen = LRW_BUFFER_SIZE;
297         if (req->cryptlen > LRW_BUFFER_SIZE) {
298                 unsigned int n = min(req->cryptlen, (unsigned int)PAGE_SIZE);
299 
300                 rctx->ext = kmalloc(n, gfp);
301                 if (rctx->ext)
302                         subreq->cryptlen = n;
303         }
304 
305         rctx->src = req->src;
306         rctx->dst = req->dst;
307         rctx->left = req->cryptlen;
308 
309         /* calculate first value of T */
310         memcpy(&rctx->t, req->iv, sizeof(rctx->t));
311 
312         /* T <- I*Key2 */
313         gf128mul_64k_bbe(&rctx->t, ctx->table);
314 
315         return 0;
316 }
317 
318 static void exit_crypt(struct skcipher_request *req)
319 {
320         struct rctx *rctx = skcipher_request_ctx(req);
321 
322         rctx->left = 0;
323 
324         if (rctx->ext)
325                 kzfree(rctx->ext);
326 }
327 
328 static int do_encrypt(struct skcipher_request *req, int err)
329 {
330         struct rctx *rctx = skcipher_request_ctx(req);
331         struct skcipher_request *subreq;
332 
333         subreq = &rctx->subreq;
334 
335         while (!err && rctx->left) {
336                 err = pre_crypt(req) ?:
337                       crypto_skcipher_encrypt(subreq) ?:
338                       post_crypt(req);
339 
340                 if (err == -EINPROGRESS || err == -EBUSY)
341                         return err;
342         }
343 
344         exit_crypt(req);
345         return err;
346 }
347 
348 static void encrypt_done(struct crypto_async_request *areq, int err)
349 {
350         struct skcipher_request *req = areq->data;
351         struct skcipher_request *subreq;
352         struct rctx *rctx;
353 
354         rctx = skcipher_request_ctx(req);
355 
356         if (err == -EINPROGRESS) {
357                 if (rctx->left != req->cryptlen)
358                         return;
359                 goto out;
360         }
361 
362         subreq = &rctx->subreq;
363         subreq->base.flags &= CRYPTO_TFM_REQ_MAY_BACKLOG;
364 
365         err = do_encrypt(req, err ?: post_crypt(req));
366         if (rctx->left)
367                 return;
368 
369 out:
370         skcipher_request_complete(req, err);
371 }
372 
373 static int encrypt(struct skcipher_request *req)
374 {
375         return do_encrypt(req, init_crypt(req, encrypt_done));
376 }
377 
378 static int do_decrypt(struct skcipher_request *req, int err)
379 {
380         struct rctx *rctx = skcipher_request_ctx(req);
381         struct skcipher_request *subreq;
382 
383         subreq = &rctx->subreq;
384 
385         while (!err && rctx->left) {
386                 err = pre_crypt(req) ?:
387                       crypto_skcipher_decrypt(subreq) ?:
388                       post_crypt(req);
389 
390                 if (err == -EINPROGRESS || err == -EBUSY)
391                         return err;
392         }
393 
394         exit_crypt(req);
395         return err;
396 }
397 
398 static void decrypt_done(struct crypto_async_request *areq, int err)
399 {
400         struct skcipher_request *req = areq->data;
401         struct skcipher_request *subreq;
402         struct rctx *rctx;
403 
404         rctx = skcipher_request_ctx(req);
405 
406         if (err == -EINPROGRESS) {
407                 if (rctx->left != req->cryptlen)
408                         return;
409                 goto out;
410         }
411 
412         subreq = &rctx->subreq;
413         subreq->base.flags &= CRYPTO_TFM_REQ_MAY_BACKLOG;
414 
415         err = do_decrypt(req, err ?: post_crypt(req));
416         if (rctx->left)
417                 return;
418 
419 out:
420         skcipher_request_complete(req, err);
421 }
422 
423 static int decrypt(struct skcipher_request *req)
424 {
425         return do_decrypt(req, init_crypt(req, decrypt_done));
426 }
427 
428 static int init_tfm(struct crypto_skcipher *tfm)
429 {
430         struct skcipher_instance *inst = skcipher_alg_instance(tfm);
431         struct crypto_skcipher_spawn *spawn = skcipher_instance_ctx(inst);
432         struct priv *ctx = crypto_skcipher_ctx(tfm);
433         struct crypto_skcipher *cipher;
434 
435         cipher = crypto_spawn_skcipher(spawn);
436         if (IS_ERR(cipher))
437                 return PTR_ERR(cipher);
438 
439         ctx->child = cipher;
440 
441         crypto_skcipher_set_reqsize(tfm, crypto_skcipher_reqsize(cipher) +
442                                          sizeof(struct rctx));
443 
444         return 0;
445 }
446 
447 static void exit_tfm(struct crypto_skcipher *tfm)
448 {
449         struct priv *ctx = crypto_skcipher_ctx(tfm);
450 
451         if (ctx->table)
452                 gf128mul_free_64k(ctx->table);
453         crypto_free_skcipher(ctx->child);
454 }
455 
456 static void free(struct skcipher_instance *inst)
457 {
458         crypto_drop_skcipher(skcipher_instance_ctx(inst));
459         kfree(inst);
460 }
461 
462 static int create(struct crypto_template *tmpl, struct rtattr **tb)
463 {
464         struct crypto_skcipher_spawn *spawn;
465         struct skcipher_instance *inst;
466         struct crypto_attr_type *algt;
467         struct skcipher_alg *alg;
468         const char *cipher_name;
469         char ecb_name[CRYPTO_MAX_ALG_NAME];
470         int err;
471 
472         algt = crypto_get_attr_type(tb);
473         if (IS_ERR(algt))
474                 return PTR_ERR(algt);
475 
476         if ((algt->type ^ CRYPTO_ALG_TYPE_SKCIPHER) & algt->mask)
477                 return -EINVAL;
478 
479         cipher_name = crypto_attr_alg_name(tb[1]);
480         if (IS_ERR(cipher_name))
481                 return PTR_ERR(cipher_name);
482 
483         inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);
484         if (!inst)
485                 return -ENOMEM;
486 
487         spawn = skcipher_instance_ctx(inst);
488 
489         crypto_set_skcipher_spawn(spawn, skcipher_crypto_instance(inst));
490         err = crypto_grab_skcipher(spawn, cipher_name, 0,
491                                    crypto_requires_sync(algt->type,
492                                                         algt->mask));
493         if (err == -ENOENT) {
494                 err = -ENAMETOOLONG;
495                 if (snprintf(ecb_name, CRYPTO_MAX_ALG_NAME, "ecb(%s)",
496                              cipher_name) >= CRYPTO_MAX_ALG_NAME)
497                         goto err_free_inst;
498 
499                 err = crypto_grab_skcipher(spawn, ecb_name, 0,
500                                            crypto_requires_sync(algt->type,
501                                                                 algt->mask));
502         }
503 
504         if (err)
505                 goto err_free_inst;
506 
507         alg = crypto_skcipher_spawn_alg(spawn);
508 
509         err = -EINVAL;
510         if (alg->base.cra_blocksize != LRW_BLOCK_SIZE)
511                 goto err_drop_spawn;
512 
513         if (crypto_skcipher_alg_ivsize(alg))
514                 goto err_drop_spawn;
515 
516         err = crypto_inst_setname(skcipher_crypto_instance(inst), "lrw",
517                                   &alg->base);
518         if (err)
519                 goto err_drop_spawn;
520 
521         err = -EINVAL;
522         cipher_name = alg->base.cra_name;
523 
524         /* Alas we screwed up the naming so we have to mangle the
525          * cipher name.
526          */
527         if (!strncmp(cipher_name, "ecb(", 4)) {
528                 unsigned len;
529 
530                 len = strlcpy(ecb_name, cipher_name + 4, sizeof(ecb_name));
531                 if (len < 2 || len >= sizeof(ecb_name))
532                         goto err_drop_spawn;
533 
534                 if (ecb_name[len - 1] != ')')
535                         goto err_drop_spawn;
536 
537                 ecb_name[len - 1] = 0;
538 
539                 if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
540                              "lrw(%s)", ecb_name) >= CRYPTO_MAX_ALG_NAME) {
541                         err = -ENAMETOOLONG;
542                         goto err_drop_spawn;
543                 }
544         } else
545                 goto err_drop_spawn;
546 
547         inst->alg.base.cra_flags = alg->base.cra_flags & CRYPTO_ALG_ASYNC;
548         inst->alg.base.cra_priority = alg->base.cra_priority;
549         inst->alg.base.cra_blocksize = LRW_BLOCK_SIZE;
550         inst->alg.base.cra_alignmask = alg->base.cra_alignmask |
551                                        (__alignof__(u64) - 1);
552 
553         inst->alg.ivsize = LRW_BLOCK_SIZE;
554         inst->alg.min_keysize = crypto_skcipher_alg_min_keysize(alg) +
555                                 LRW_BLOCK_SIZE;
556         inst->alg.max_keysize = crypto_skcipher_alg_max_keysize(alg) +
557                                 LRW_BLOCK_SIZE;
558 
559         inst->alg.base.cra_ctxsize = sizeof(struct priv);
560 
561         inst->alg.init = init_tfm;
562         inst->alg.exit = exit_tfm;
563 
564         inst->alg.setkey = setkey;
565         inst->alg.encrypt = encrypt;
566         inst->alg.decrypt = decrypt;
567 
568         inst->free = free;
569 
570         err = skcipher_register_instance(tmpl, inst);
571         if (err)
572                 goto err_drop_spawn;
573 
574 out:
575         return err;
576 
577 err_drop_spawn:
578         crypto_drop_skcipher(spawn);
579 err_free_inst:
580         kfree(inst);
581         goto out;
582 }
583 
584 static struct crypto_template crypto_tmpl = {
585         .name = "lrw",
586         .create = create,
587         .module = THIS_MODULE,
588 };
589 
590 static int __init crypto_module_init(void)
591 {
592         return crypto_register_template(&crypto_tmpl);
593 }
594 
595 static void __exit crypto_module_exit(void)
596 {
597         crypto_unregister_template(&crypto_tmpl);
598 }
599 
600 module_init(crypto_module_init);
601 module_exit(crypto_module_exit);
602 
603 MODULE_LICENSE("GPL");
604 MODULE_DESCRIPTION("LRW block cipher mode");
605 MODULE_ALIAS_CRYPTO("lrw");
606 

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