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1 | /* | |
2 | * CTR: Counter mode | |
3 | * | |
4 | * (C) Copyright IBM Corp. 2007 - Joy Latten <latten@us.ibm.com> | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or modify it | |
7 | * under the terms of the GNU General Public License as published by the Free | |
8 | * Software Foundation; either version 2 of the License, or (at your option) | |
9 | * any later version. | |
10 | * | |
11 | */ | |
12 | ||
13 | #include <crypto/algapi.h> | |
14 | #include <crypto/ctr.h> | |
15 | #include <crypto/internal/skcipher.h> | |
16 | #include <linux/err.h> | |
17 | #include <linux/init.h> | |
18 | #include <linux/kernel.h> | |
19 | #include <linux/module.h> | |
20 | #include <linux/random.h> | |
21 | #include <linux/scatterlist.h> | |
22 | #include <linux/slab.h> | |
23 | ||
24 | struct crypto_ctr_ctx { | |
25 | struct crypto_cipher *child; | |
26 | }; | |
27 | ||
28 | struct crypto_rfc3686_ctx { | |
29 | struct crypto_skcipher *child; | |
30 | u8 nonce[CTR_RFC3686_NONCE_SIZE]; | |
31 | }; | |
32 | ||
33 | struct crypto_rfc3686_req_ctx { | |
34 | u8 iv[CTR_RFC3686_BLOCK_SIZE]; | |
35 | struct skcipher_request subreq CRYPTO_MINALIGN_ATTR; | |
36 | }; | |
37 | ||
38 | static int crypto_ctr_setkey(struct crypto_tfm *parent, const u8 *key, | |
39 | unsigned int keylen) | |
40 | { | |
41 | struct crypto_ctr_ctx *ctx = crypto_tfm_ctx(parent); | |
42 | struct crypto_cipher *child = ctx->child; | |
43 | int err; | |
44 | ||
45 | crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK); | |
46 | crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) & | |
47 | CRYPTO_TFM_REQ_MASK); | |
48 | err = crypto_cipher_setkey(child, key, keylen); | |
49 | crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) & | |
50 | CRYPTO_TFM_RES_MASK); | |
51 | ||
52 | return err; | |
53 | } | |
54 | ||
55 | static void crypto_ctr_crypt_final(struct blkcipher_walk *walk, | |
56 | struct crypto_cipher *tfm) | |
57 | { | |
58 | unsigned int bsize = crypto_cipher_blocksize(tfm); | |
59 | unsigned long alignmask = crypto_cipher_alignmask(tfm); | |
60 | u8 *ctrblk = walk->iv; | |
61 | u8 tmp[bsize + alignmask]; | |
62 | u8 *keystream = PTR_ALIGN(tmp + 0, alignmask + 1); | |
63 | u8 *src = walk->src.virt.addr; | |
64 | u8 *dst = walk->dst.virt.addr; | |
65 | unsigned int nbytes = walk->nbytes; | |
66 | ||
67 | crypto_cipher_encrypt_one(tfm, keystream, ctrblk); | |
68 | crypto_xor(keystream, src, nbytes); | |
69 | memcpy(dst, keystream, nbytes); | |
70 | ||
71 | crypto_inc(ctrblk, bsize); | |
72 | } | |
73 | ||
74 | static int crypto_ctr_crypt_segment(struct blkcipher_walk *walk, | |
75 | struct crypto_cipher *tfm) | |
76 | { | |
77 | void (*fn)(struct crypto_tfm *, u8 *, const u8 *) = | |
78 | crypto_cipher_alg(tfm)->cia_encrypt; | |
79 | unsigned int bsize = crypto_cipher_blocksize(tfm); | |
80 | u8 *ctrblk = walk->iv; | |
81 | u8 *src = walk->src.virt.addr; | |
82 | u8 *dst = walk->dst.virt.addr; | |
83 | unsigned int nbytes = walk->nbytes; | |
84 | ||
85 | do { | |
86 | /* create keystream */ | |
87 | fn(crypto_cipher_tfm(tfm), dst, ctrblk); | |
88 | crypto_xor(dst, src, bsize); | |
89 | ||
90 | /* increment counter in counterblock */ | |
91 | crypto_inc(ctrblk, bsize); | |
92 | ||
93 | src += bsize; | |
94 | dst += bsize; | |
95 | } while ((nbytes -= bsize) >= bsize); | |
96 | ||
97 | return nbytes; | |
98 | } | |
99 | ||
100 | static int crypto_ctr_crypt_inplace(struct blkcipher_walk *walk, | |
101 | struct crypto_cipher *tfm) | |
102 | { | |
103 | void (*fn)(struct crypto_tfm *, u8 *, const u8 *) = | |
104 | crypto_cipher_alg(tfm)->cia_encrypt; | |
105 | unsigned int bsize = crypto_cipher_blocksize(tfm); | |
106 | unsigned long alignmask = crypto_cipher_alignmask(tfm); | |
107 | unsigned int nbytes = walk->nbytes; | |
108 | u8 *ctrblk = walk->iv; | |
109 | u8 *src = walk->src.virt.addr; | |
110 | u8 tmp[bsize + alignmask]; | |
111 | u8 *keystream = PTR_ALIGN(tmp + 0, alignmask + 1); | |
112 | ||
113 | do { | |
114 | /* create keystream */ | |
115 | fn(crypto_cipher_tfm(tfm), keystream, ctrblk); | |
116 | crypto_xor(src, keystream, bsize); | |
117 | ||
118 | /* increment counter in counterblock */ | |
119 | crypto_inc(ctrblk, bsize); | |
120 | ||
121 | src += bsize; | |
122 | } while ((nbytes -= bsize) >= bsize); | |
123 | ||
124 | return nbytes; | |
125 | } | |
126 | ||
127 | static int crypto_ctr_crypt(struct blkcipher_desc *desc, | |
128 | struct scatterlist *dst, struct scatterlist *src, | |
129 | unsigned int nbytes) | |
130 | { | |
131 | struct blkcipher_walk walk; | |
132 | struct crypto_blkcipher *tfm = desc->tfm; | |
133 | struct crypto_ctr_ctx *ctx = crypto_blkcipher_ctx(tfm); | |
134 | struct crypto_cipher *child = ctx->child; | |
135 | unsigned int bsize = crypto_cipher_blocksize(child); | |
136 | int err; | |
137 | ||
138 | blkcipher_walk_init(&walk, dst, src, nbytes); | |
139 | err = blkcipher_walk_virt_block(desc, &walk, bsize); | |
140 | ||
141 | while (walk.nbytes >= bsize) { | |
142 | if (walk.src.virt.addr == walk.dst.virt.addr) | |
143 | nbytes = crypto_ctr_crypt_inplace(&walk, child); | |
144 | else | |
145 | nbytes = crypto_ctr_crypt_segment(&walk, child); | |
146 | ||
147 | err = blkcipher_walk_done(desc, &walk, nbytes); | |
148 | } | |
149 | ||
150 | if (walk.nbytes) { | |
151 | crypto_ctr_crypt_final(&walk, child); | |
152 | err = blkcipher_walk_done(desc, &walk, 0); | |
153 | } | |
154 | ||
155 | return err; | |
156 | } | |
157 | ||
158 | static int crypto_ctr_init_tfm(struct crypto_tfm *tfm) | |
159 | { | |
160 | struct crypto_instance *inst = (void *)tfm->__crt_alg; | |
161 | struct crypto_spawn *spawn = crypto_instance_ctx(inst); | |
162 | struct crypto_ctr_ctx *ctx = crypto_tfm_ctx(tfm); | |
163 | struct crypto_cipher *cipher; | |
164 | ||
165 | cipher = crypto_spawn_cipher(spawn); | |
166 | if (IS_ERR(cipher)) | |
167 | return PTR_ERR(cipher); | |
168 | ||
169 | ctx->child = cipher; | |
170 | ||
171 | return 0; | |
172 | } | |
173 | ||
174 | static void crypto_ctr_exit_tfm(struct crypto_tfm *tfm) | |
175 | { | |
176 | struct crypto_ctr_ctx *ctx = crypto_tfm_ctx(tfm); | |
177 | ||
178 | crypto_free_cipher(ctx->child); | |
179 | } | |
180 | ||
181 | static struct crypto_instance *crypto_ctr_alloc(struct rtattr **tb) | |
182 | { | |
183 | struct crypto_instance *inst; | |
184 | struct crypto_attr_type *algt; | |
185 | struct crypto_alg *alg; | |
186 | u32 mask; | |
187 | int err; | |
188 | ||
189 | err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER); | |
190 | if (err) | |
191 | return ERR_PTR(err); | |
192 | ||
193 | algt = crypto_get_attr_type(tb); | |
194 | if (IS_ERR(algt)) | |
195 | return ERR_CAST(algt); | |
196 | ||
197 | mask = CRYPTO_ALG_TYPE_MASK | | |
198 | crypto_requires_off(algt->type, algt->mask, | |
199 | CRYPTO_ALG_NEED_FALLBACK); | |
200 | ||
201 | alg = crypto_attr_alg(tb[1], CRYPTO_ALG_TYPE_CIPHER, mask); | |
202 | if (IS_ERR(alg)) | |
203 | return ERR_CAST(alg); | |
204 | ||
205 | /* Block size must be >= 4 bytes. */ | |
206 | err = -EINVAL; | |
207 | if (alg->cra_blocksize < 4) | |
208 | goto out_put_alg; | |
209 | ||
210 | /* If this is false we'd fail the alignment of crypto_inc. */ | |
211 | if (alg->cra_blocksize % 4) | |
212 | goto out_put_alg; | |
213 | ||
214 | inst = crypto_alloc_instance("ctr", alg); | |
215 | if (IS_ERR(inst)) | |
216 | goto out; | |
217 | ||
218 | inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER; | |
219 | inst->alg.cra_priority = alg->cra_priority; | |
220 | inst->alg.cra_blocksize = 1; | |
221 | inst->alg.cra_alignmask = alg->cra_alignmask; | |
222 | inst->alg.cra_type = &crypto_blkcipher_type; | |
223 | ||
224 | inst->alg.cra_blkcipher.ivsize = alg->cra_blocksize; | |
225 | inst->alg.cra_blkcipher.min_keysize = alg->cra_cipher.cia_min_keysize; | |
226 | inst->alg.cra_blkcipher.max_keysize = alg->cra_cipher.cia_max_keysize; | |
227 | ||
228 | inst->alg.cra_ctxsize = sizeof(struct crypto_ctr_ctx); | |
229 | ||
230 | inst->alg.cra_init = crypto_ctr_init_tfm; | |
231 | inst->alg.cra_exit = crypto_ctr_exit_tfm; | |
232 | ||
233 | inst->alg.cra_blkcipher.setkey = crypto_ctr_setkey; | |
234 | inst->alg.cra_blkcipher.encrypt = crypto_ctr_crypt; | |
235 | inst->alg.cra_blkcipher.decrypt = crypto_ctr_crypt; | |
236 | ||
237 | inst->alg.cra_blkcipher.geniv = "chainiv"; | |
238 | ||
239 | out: | |
240 | crypto_mod_put(alg); | |
241 | return inst; | |
242 | ||
243 | out_put_alg: | |
244 | inst = ERR_PTR(err); | |
245 | goto out; | |
246 | } | |
247 | ||
248 | static void crypto_ctr_free(struct crypto_instance *inst) | |
249 | { | |
250 | crypto_drop_spawn(crypto_instance_ctx(inst)); | |
251 | kfree(inst); | |
252 | } | |
253 | ||
254 | static struct crypto_template crypto_ctr_tmpl = { | |
255 | .name = "ctr", | |
256 | .alloc = crypto_ctr_alloc, | |
257 | .free = crypto_ctr_free, | |
258 | .module = THIS_MODULE, | |
259 | }; | |
260 | ||
261 | static int crypto_rfc3686_setkey(struct crypto_skcipher *parent, | |
262 | const u8 *key, unsigned int keylen) | |
263 | { | |
264 | struct crypto_rfc3686_ctx *ctx = crypto_skcipher_ctx(parent); | |
265 | struct crypto_skcipher *child = ctx->child; | |
266 | int err; | |
267 | ||
268 | /* the nonce is stored in bytes at end of key */ | |
269 | if (keylen < CTR_RFC3686_NONCE_SIZE) | |
270 | return -EINVAL; | |
271 | ||
272 | memcpy(ctx->nonce, key + (keylen - CTR_RFC3686_NONCE_SIZE), | |
273 | CTR_RFC3686_NONCE_SIZE); | |
274 | ||
275 | keylen -= CTR_RFC3686_NONCE_SIZE; | |
276 | ||
277 | crypto_skcipher_clear_flags(child, CRYPTO_TFM_REQ_MASK); | |
278 | crypto_skcipher_set_flags(child, crypto_skcipher_get_flags(parent) & | |
279 | CRYPTO_TFM_REQ_MASK); | |
280 | err = crypto_skcipher_setkey(child, key, keylen); | |
281 | crypto_skcipher_set_flags(parent, crypto_skcipher_get_flags(child) & | |
282 | CRYPTO_TFM_RES_MASK); | |
283 | ||
284 | return err; | |
285 | } | |
286 | ||
287 | static int crypto_rfc3686_crypt(struct skcipher_request *req) | |
288 | { | |
289 | struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); | |
290 | struct crypto_rfc3686_ctx *ctx = crypto_skcipher_ctx(tfm); | |
291 | struct crypto_skcipher *child = ctx->child; | |
292 | unsigned long align = crypto_skcipher_alignmask(tfm); | |
293 | struct crypto_rfc3686_req_ctx *rctx = | |
294 | (void *)PTR_ALIGN((u8 *)skcipher_request_ctx(req), align + 1); | |
295 | struct skcipher_request *subreq = &rctx->subreq; | |
296 | u8 *iv = rctx->iv; | |
297 | ||
298 | /* set up counter block */ | |
299 | memcpy(iv, ctx->nonce, CTR_RFC3686_NONCE_SIZE); | |
300 | memcpy(iv + CTR_RFC3686_NONCE_SIZE, req->iv, CTR_RFC3686_IV_SIZE); | |
301 | ||
302 | /* initialize counter portion of counter block */ | |
303 | *(__be32 *)(iv + CTR_RFC3686_NONCE_SIZE + CTR_RFC3686_IV_SIZE) = | |
304 | cpu_to_be32(1); | |
305 | ||
306 | skcipher_request_set_tfm(subreq, child); | |
307 | skcipher_request_set_callback(subreq, req->base.flags, | |
308 | req->base.complete, req->base.data); | |
309 | skcipher_request_set_crypt(subreq, req->src, req->dst, | |
310 | req->cryptlen, iv); | |
311 | ||
312 | return crypto_skcipher_encrypt(subreq); | |
313 | } | |
314 | ||
315 | static int crypto_rfc3686_init_tfm(struct crypto_skcipher *tfm) | |
316 | { | |
317 | struct skcipher_instance *inst = skcipher_alg_instance(tfm); | |
318 | struct crypto_skcipher_spawn *spawn = skcipher_instance_ctx(inst); | |
319 | struct crypto_rfc3686_ctx *ctx = crypto_skcipher_ctx(tfm); | |
320 | struct crypto_skcipher *cipher; | |
321 | unsigned long align; | |
322 | unsigned int reqsize; | |
323 | ||
324 | cipher = crypto_spawn_skcipher(spawn); | |
325 | if (IS_ERR(cipher)) | |
326 | return PTR_ERR(cipher); | |
327 | ||
328 | ctx->child = cipher; | |
329 | ||
330 | align = crypto_skcipher_alignmask(tfm); | |
331 | align &= ~(crypto_tfm_ctx_alignment() - 1); | |
332 | reqsize = align + sizeof(struct crypto_rfc3686_req_ctx) + | |
333 | crypto_skcipher_reqsize(cipher); | |
334 | crypto_skcipher_set_reqsize(tfm, reqsize); | |
335 | ||
336 | return 0; | |
337 | } | |
338 | ||
339 | static void crypto_rfc3686_exit_tfm(struct crypto_skcipher *tfm) | |
340 | { | |
341 | struct crypto_rfc3686_ctx *ctx = crypto_skcipher_ctx(tfm); | |
342 | ||
343 | crypto_free_skcipher(ctx->child); | |
344 | } | |
345 | ||
346 | static void crypto_rfc3686_free(struct skcipher_instance *inst) | |
347 | { | |
348 | struct crypto_skcipher_spawn *spawn = skcipher_instance_ctx(inst); | |
349 | ||
350 | crypto_drop_skcipher(spawn); | |
351 | kfree(inst); | |
352 | } | |
353 | ||
354 | static int crypto_rfc3686_create(struct crypto_template *tmpl, | |
355 | struct rtattr **tb) | |
356 | { | |
357 | struct crypto_attr_type *algt; | |
358 | struct skcipher_instance *inst; | |
359 | struct skcipher_alg *alg; | |
360 | struct crypto_skcipher_spawn *spawn; | |
361 | const char *cipher_name; | |
362 | u32 mask; | |
363 | ||
364 | int err; | |
365 | ||
366 | algt = crypto_get_attr_type(tb); | |
367 | if (IS_ERR(algt)) | |
368 | return PTR_ERR(algt); | |
369 | ||
370 | if ((algt->type ^ CRYPTO_ALG_TYPE_SKCIPHER) & algt->mask) | |
371 | return -EINVAL; | |
372 | ||
373 | cipher_name = crypto_attr_alg_name(tb[1]); | |
374 | if (IS_ERR(cipher_name)) | |
375 | return PTR_ERR(cipher_name); | |
376 | ||
377 | inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL); | |
378 | if (!inst) | |
379 | return -ENOMEM; | |
380 | ||
381 | mask = crypto_requires_sync(algt->type, algt->mask) | | |
382 | crypto_requires_off(algt->type, algt->mask, | |
383 | CRYPTO_ALG_NEED_FALLBACK); | |
384 | ||
385 | spawn = skcipher_instance_ctx(inst); | |
386 | ||
387 | crypto_set_skcipher_spawn(spawn, skcipher_crypto_instance(inst)); | |
388 | err = crypto_grab_skcipher(spawn, cipher_name, 0, mask); | |
389 | if (err) | |
390 | goto err_free_inst; | |
391 | ||
392 | alg = crypto_spawn_skcipher_alg(spawn); | |
393 | ||
394 | /* We only support 16-byte blocks. */ | |
395 | err = -EINVAL; | |
396 | if (crypto_skcipher_alg_ivsize(alg) != CTR_RFC3686_BLOCK_SIZE) | |
397 | goto err_drop_spawn; | |
398 | ||
399 | /* Not a stream cipher? */ | |
400 | if (alg->base.cra_blocksize != 1) | |
401 | goto err_drop_spawn; | |
402 | ||
403 | err = -ENAMETOOLONG; | |
404 | if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME, | |
405 | "rfc3686(%s)", alg->base.cra_name) >= CRYPTO_MAX_ALG_NAME) | |
406 | goto err_drop_spawn; | |
407 | if (snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME, | |
408 | "rfc3686(%s)", alg->base.cra_driver_name) >= | |
409 | CRYPTO_MAX_ALG_NAME) | |
410 | goto err_drop_spawn; | |
411 | ||
412 | inst->alg.base.cra_priority = alg->base.cra_priority; | |
413 | inst->alg.base.cra_blocksize = 1; | |
414 | inst->alg.base.cra_alignmask = alg->base.cra_alignmask; | |
415 | ||
416 | inst->alg.base.cra_flags = alg->base.cra_flags & CRYPTO_ALG_ASYNC; | |
417 | ||
418 | inst->alg.ivsize = CTR_RFC3686_IV_SIZE; | |
419 | inst->alg.chunksize = crypto_skcipher_alg_chunksize(alg); | |
420 | inst->alg.min_keysize = crypto_skcipher_alg_min_keysize(alg) + | |
421 | CTR_RFC3686_NONCE_SIZE; | |
422 | inst->alg.max_keysize = crypto_skcipher_alg_max_keysize(alg) + | |
423 | CTR_RFC3686_NONCE_SIZE; | |
424 | ||
425 | inst->alg.setkey = crypto_rfc3686_setkey; | |
426 | inst->alg.encrypt = crypto_rfc3686_crypt; | |
427 | inst->alg.decrypt = crypto_rfc3686_crypt; | |
428 | ||
429 | inst->alg.base.cra_ctxsize = sizeof(struct crypto_rfc3686_ctx); | |
430 | ||
431 | inst->alg.init = crypto_rfc3686_init_tfm; | |
432 | inst->alg.exit = crypto_rfc3686_exit_tfm; | |
433 | ||
434 | inst->free = crypto_rfc3686_free; | |
435 | ||
436 | err = skcipher_register_instance(tmpl, inst); | |
437 | if (err) | |
438 | goto err_drop_spawn; | |
439 | ||
440 | out: | |
441 | return err; | |
442 | ||
443 | err_drop_spawn: | |
444 | crypto_drop_skcipher(spawn); | |
445 | err_free_inst: | |
446 | kfree(inst); | |
447 | goto out; | |
448 | } | |
449 | ||
450 | static struct crypto_template crypto_rfc3686_tmpl = { | |
451 | .name = "rfc3686", | |
452 | .create = crypto_rfc3686_create, | |
453 | .module = THIS_MODULE, | |
454 | }; | |
455 | ||
456 | static int __init crypto_ctr_module_init(void) | |
457 | { | |
458 | int err; | |
459 | ||
460 | err = crypto_register_template(&crypto_ctr_tmpl); | |
461 | if (err) | |
462 | goto out; | |
463 | ||
464 | err = crypto_register_template(&crypto_rfc3686_tmpl); | |
465 | if (err) | |
466 | goto out_drop_ctr; | |
467 | ||
468 | out: | |
469 | return err; | |
470 | ||
471 | out_drop_ctr: | |
472 | crypto_unregister_template(&crypto_ctr_tmpl); | |
473 | goto out; | |
474 | } | |
475 | ||
476 | static void __exit crypto_ctr_module_exit(void) | |
477 | { | |
478 | crypto_unregister_template(&crypto_rfc3686_tmpl); | |
479 | crypto_unregister_template(&crypto_ctr_tmpl); | |
480 | } | |
481 | ||
482 | module_init(crypto_ctr_module_init); | |
483 | module_exit(crypto_ctr_module_exit); | |
484 | ||
485 | MODULE_LICENSE("GPL"); | |
486 | MODULE_DESCRIPTION("CTR Counter block mode"); | |
487 | MODULE_ALIAS_CRYPTO("rfc3686"); | |
488 | MODULE_ALIAS_CRYPTO("ctr"); |