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