Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
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
24struct crypto_ctr_ctx {
25 struct crypto_cipher *child;
26};
27
28struct crypto_rfc3686_ctx {
29 struct crypto_skcipher *child;
30 u8 nonce[CTR_RFC3686_NONCE_SIZE];
31};
32
33struct crypto_rfc3686_req_ctx {
34 u8 iv[CTR_RFC3686_BLOCK_SIZE];
35 struct skcipher_request subreq CRYPTO_MINALIGN_ATTR;
36};
37
38static 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
55static 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
73static 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
99static 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
126static 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
157static 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
173static 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
180static 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
236out:
237 crypto_mod_put(alg);
238 return inst;
239
240out_put_alg:
241 inst = ERR_PTR(err);
242 goto out;
243}
244
245static void crypto_ctr_free(struct crypto_instance *inst)
246{
247 crypto_drop_spawn(crypto_instance_ctx(inst));
248 kfree(inst);
249}
250
251static struct crypto_template crypto_ctr_tmpl = {
252 .name = "ctr",
253 .alloc = crypto_ctr_alloc,
254 .free = crypto_ctr_free,
255 .module = THIS_MODULE,
256};
257
258static int crypto_rfc3686_setkey(struct crypto_skcipher *parent,
259 const u8 *key, unsigned int keylen)
260{
261 struct crypto_rfc3686_ctx *ctx = crypto_skcipher_ctx(parent);
262 struct crypto_skcipher *child = ctx->child;
263 int err;
264
265 /* the nonce is stored in bytes at end of key */
266 if (keylen < CTR_RFC3686_NONCE_SIZE)
267 return -EINVAL;
268
269 memcpy(ctx->nonce, key + (keylen - CTR_RFC3686_NONCE_SIZE),
270 CTR_RFC3686_NONCE_SIZE);
271
272 keylen -= CTR_RFC3686_NONCE_SIZE;
273
274 crypto_skcipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
275 crypto_skcipher_set_flags(child, crypto_skcipher_get_flags(parent) &
276 CRYPTO_TFM_REQ_MASK);
277 err = crypto_skcipher_setkey(child, key, keylen);
278 crypto_skcipher_set_flags(parent, crypto_skcipher_get_flags(child) &
279 CRYPTO_TFM_RES_MASK);
280
281 return err;
282}
283
284static int crypto_rfc3686_crypt(struct skcipher_request *req)
285{
286 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
287 struct crypto_rfc3686_ctx *ctx = crypto_skcipher_ctx(tfm);
288 struct crypto_skcipher *child = ctx->child;
289 unsigned long align = crypto_skcipher_alignmask(tfm);
290 struct crypto_rfc3686_req_ctx *rctx =
291 (void *)PTR_ALIGN((u8 *)skcipher_request_ctx(req), align + 1);
292 struct skcipher_request *subreq = &rctx->subreq;
293 u8 *iv = rctx->iv;
294
295 /* set up counter block */
296 memcpy(iv, ctx->nonce, CTR_RFC3686_NONCE_SIZE);
297 memcpy(iv + CTR_RFC3686_NONCE_SIZE, req->iv, CTR_RFC3686_IV_SIZE);
298
299 /* initialize counter portion of counter block */
300 *(__be32 *)(iv + CTR_RFC3686_NONCE_SIZE + CTR_RFC3686_IV_SIZE) =
301 cpu_to_be32(1);
302
303 skcipher_request_set_tfm(subreq, child);
304 skcipher_request_set_callback(subreq, req->base.flags,
305 req->base.complete, req->base.data);
306 skcipher_request_set_crypt(subreq, req->src, req->dst,
307 req->cryptlen, iv);
308
309 return crypto_skcipher_encrypt(subreq);
310}
311
312static int crypto_rfc3686_init_tfm(struct crypto_skcipher *tfm)
313{
314 struct skcipher_instance *inst = skcipher_alg_instance(tfm);
315 struct crypto_skcipher_spawn *spawn = skcipher_instance_ctx(inst);
316 struct crypto_rfc3686_ctx *ctx = crypto_skcipher_ctx(tfm);
317 struct crypto_skcipher *cipher;
318 unsigned long align;
319 unsigned int reqsize;
320
321 cipher = crypto_spawn_skcipher(spawn);
322 if (IS_ERR(cipher))
323 return PTR_ERR(cipher);
324
325 ctx->child = cipher;
326
327 align = crypto_skcipher_alignmask(tfm);
328 align &= ~(crypto_tfm_ctx_alignment() - 1);
329 reqsize = align + sizeof(struct crypto_rfc3686_req_ctx) +
330 crypto_skcipher_reqsize(cipher);
331 crypto_skcipher_set_reqsize(tfm, reqsize);
332
333 return 0;
334}
335
336static void crypto_rfc3686_exit_tfm(struct crypto_skcipher *tfm)
337{
338 struct crypto_rfc3686_ctx *ctx = crypto_skcipher_ctx(tfm);
339
340 crypto_free_skcipher(ctx->child);
341}
342
343static void crypto_rfc3686_free(struct skcipher_instance *inst)
344{
345 struct crypto_skcipher_spawn *spawn = skcipher_instance_ctx(inst);
346
347 crypto_drop_skcipher(spawn);
348 kfree(inst);
349}
350
351static int crypto_rfc3686_create(struct crypto_template *tmpl,
352 struct rtattr **tb)
353{
354 struct crypto_attr_type *algt;
355 struct skcipher_instance *inst;
356 struct skcipher_alg *alg;
357 struct crypto_skcipher_spawn *spawn;
358 const char *cipher_name;
359 u32 mask;
360
361 int err;
362
363 algt = crypto_get_attr_type(tb);
364 if (IS_ERR(algt))
365 return PTR_ERR(algt);
366
367 if ((algt->type ^ CRYPTO_ALG_TYPE_SKCIPHER) & algt->mask)
368 return -EINVAL;
369
370 cipher_name = crypto_attr_alg_name(tb[1]);
371 if (IS_ERR(cipher_name))
372 return PTR_ERR(cipher_name);
373
374 inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);
375 if (!inst)
376 return -ENOMEM;
377
378 mask = crypto_requires_sync(algt->type, algt->mask) |
379 crypto_requires_off(algt->type, algt->mask,
380 CRYPTO_ALG_NEED_FALLBACK);
381
382 spawn = skcipher_instance_ctx(inst);
383
384 crypto_set_skcipher_spawn(spawn, skcipher_crypto_instance(inst));
385 err = crypto_grab_skcipher(spawn, cipher_name, 0, mask);
386 if (err)
387 goto err_free_inst;
388
389 alg = crypto_spawn_skcipher_alg(spawn);
390
391 /* We only support 16-byte blocks. */
392 err = -EINVAL;
393 if (crypto_skcipher_alg_ivsize(alg) != CTR_RFC3686_BLOCK_SIZE)
394 goto err_drop_spawn;
395
396 /* Not a stream cipher? */
397 if (alg->base.cra_blocksize != 1)
398 goto err_drop_spawn;
399
400 err = -ENAMETOOLONG;
401 if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
402 "rfc3686(%s)", alg->base.cra_name) >= CRYPTO_MAX_ALG_NAME)
403 goto err_drop_spawn;
404 if (snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME,
405 "rfc3686(%s)", alg->base.cra_driver_name) >=
406 CRYPTO_MAX_ALG_NAME)
407 goto err_drop_spawn;
408
409 inst->alg.base.cra_priority = alg->base.cra_priority;
410 inst->alg.base.cra_blocksize = 1;
411 inst->alg.base.cra_alignmask = alg->base.cra_alignmask;
412
413 inst->alg.base.cra_flags = alg->base.cra_flags & CRYPTO_ALG_ASYNC;
414
415 inst->alg.ivsize = CTR_RFC3686_IV_SIZE;
416 inst->alg.chunksize = crypto_skcipher_alg_chunksize(alg);
417 inst->alg.min_keysize = crypto_skcipher_alg_min_keysize(alg) +
418 CTR_RFC3686_NONCE_SIZE;
419 inst->alg.max_keysize = crypto_skcipher_alg_max_keysize(alg) +
420 CTR_RFC3686_NONCE_SIZE;
421
422 inst->alg.setkey = crypto_rfc3686_setkey;
423 inst->alg.encrypt = crypto_rfc3686_crypt;
424 inst->alg.decrypt = crypto_rfc3686_crypt;
425
426 inst->alg.base.cra_ctxsize = sizeof(struct crypto_rfc3686_ctx);
427
428 inst->alg.init = crypto_rfc3686_init_tfm;
429 inst->alg.exit = crypto_rfc3686_exit_tfm;
430
431 inst->free = crypto_rfc3686_free;
432
433 err = skcipher_register_instance(tmpl, inst);
434 if (err)
435 goto err_drop_spawn;
436
437out:
438 return err;
439
440err_drop_spawn:
441 crypto_drop_skcipher(spawn);
442err_free_inst:
443 kfree(inst);
444 goto out;
445}
446
447static struct crypto_template crypto_rfc3686_tmpl = {
448 .name = "rfc3686",
449 .create = crypto_rfc3686_create,
450 .module = THIS_MODULE,
451};
452
453static int __init crypto_ctr_module_init(void)
454{
455 int err;
456
457 err = crypto_register_template(&crypto_ctr_tmpl);
458 if (err)
459 goto out;
460
461 err = crypto_register_template(&crypto_rfc3686_tmpl);
462 if (err)
463 goto out_drop_ctr;
464
465out:
466 return err;
467
468out_drop_ctr:
469 crypto_unregister_template(&crypto_ctr_tmpl);
470 goto out;
471}
472
473static void __exit crypto_ctr_module_exit(void)
474{
475 crypto_unregister_template(&crypto_rfc3686_tmpl);
476 crypto_unregister_template(&crypto_ctr_tmpl);
477}
478
479module_init(crypto_ctr_module_init);
480module_exit(crypto_ctr_module_exit);
481
482MODULE_LICENSE("GPL");
483MODULE_DESCRIPTION("CTR Counter block mode");
484MODULE_ALIAS_CRYPTO("rfc3686");
485MODULE_ALIAS_CRYPTO("ctr");