xref: /openbmc/linux/crypto/hctr2.c (revision 255e48eb)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * HCTR2 length-preserving encryption mode
4  *
5  * Copyright 2021 Google LLC
6  */
7 
8 
9 /*
10  * HCTR2 is a length-preserving encryption mode that is efficient on
11  * processors with instructions to accelerate AES and carryless
12  * multiplication, e.g. x86 processors with AES-NI and CLMUL, and ARM
13  * processors with the ARMv8 crypto extensions.
14  *
15  * For more details, see the paper: "Length-preserving encryption with HCTR2"
16  * (https://eprint.iacr.org/2021/1441.pdf)
17  */
18 
19 #include <crypto/internal/cipher.h>
20 #include <crypto/internal/hash.h>
21 #include <crypto/internal/skcipher.h>
22 #include <crypto/polyval.h>
23 #include <crypto/scatterwalk.h>
24 #include <linux/module.h>
25 
26 #define BLOCKCIPHER_BLOCK_SIZE		16
27 
28 /*
29  * The specification allows variable-length tweaks, but Linux's crypto API
30  * currently only allows algorithms to support a single length.  The "natural"
31  * tweak length for HCTR2 is 16, since that fits into one POLYVAL block for
32  * the best performance.  But longer tweaks are useful for fscrypt, to avoid
33  * needing to derive per-file keys.  So instead we use two blocks, or 32 bytes.
34  */
35 #define TWEAK_SIZE		32
36 
37 struct hctr2_instance_ctx {
38 	struct crypto_cipher_spawn blockcipher_spawn;
39 	struct crypto_skcipher_spawn xctr_spawn;
40 	struct crypto_shash_spawn polyval_spawn;
41 };
42 
43 struct hctr2_tfm_ctx {
44 	struct crypto_cipher *blockcipher;
45 	struct crypto_skcipher *xctr;
46 	struct crypto_shash *polyval;
47 	u8 L[BLOCKCIPHER_BLOCK_SIZE];
48 	int hashed_tweak_offset;
49 	/*
50 	 * This struct is allocated with extra space for two exported hash
51 	 * states.  Since the hash state size is not known at compile-time, we
52 	 * can't add these to the struct directly.
53 	 *
54 	 * hashed_tweaklen_divisible;
55 	 * hashed_tweaklen_remainder;
56 	 */
57 };
58 
59 struct hctr2_request_ctx {
60 	u8 first_block[BLOCKCIPHER_BLOCK_SIZE];
61 	u8 xctr_iv[BLOCKCIPHER_BLOCK_SIZE];
62 	struct scatterlist *bulk_part_dst;
63 	struct scatterlist *bulk_part_src;
64 	struct scatterlist sg_src[2];
65 	struct scatterlist sg_dst[2];
66 	/*
67 	 * Sub-request sizes are unknown at compile-time, so they need to go
68 	 * after the members with known sizes.
69 	 */
70 	union {
71 		struct shash_desc hash_desc;
72 		struct skcipher_request xctr_req;
73 	} u;
74 	/*
75 	 * This struct is allocated with extra space for one exported hash
76 	 * state.  Since the hash state size is not known at compile-time, we
77 	 * can't add it to the struct directly.
78 	 *
79 	 * hashed_tweak;
80 	 */
81 };
82 
hctr2_hashed_tweaklen(const struct hctr2_tfm_ctx * tctx,bool has_remainder)83 static inline u8 *hctr2_hashed_tweaklen(const struct hctr2_tfm_ctx *tctx,
84 					bool has_remainder)
85 {
86 	u8 *p = (u8 *)tctx + sizeof(*tctx);
87 
88 	if (has_remainder) /* For messages not a multiple of block length */
89 		p += crypto_shash_statesize(tctx->polyval);
90 	return p;
91 }
92 
hctr2_hashed_tweak(const struct hctr2_tfm_ctx * tctx,struct hctr2_request_ctx * rctx)93 static inline u8 *hctr2_hashed_tweak(const struct hctr2_tfm_ctx *tctx,
94 				     struct hctr2_request_ctx *rctx)
95 {
96 	return (u8 *)rctx + tctx->hashed_tweak_offset;
97 }
98 
99 /*
100  * The input data for each HCTR2 hash step begins with a 16-byte block that
101  * contains the tweak length and a flag that indicates whether the input is evenly
102  * divisible into blocks.  Since this implementation only supports one tweak
103  * length, we precompute the two hash states resulting from hashing the two
104  * possible values of this initial block.  This reduces by one block the amount of
105  * data that needs to be hashed for each encryption/decryption
106  *
107  * These precomputed hashes are stored in hctr2_tfm_ctx.
108  */
hctr2_hash_tweaklen(struct hctr2_tfm_ctx * tctx,bool has_remainder)109 static int hctr2_hash_tweaklen(struct hctr2_tfm_ctx *tctx, bool has_remainder)
110 {
111 	SHASH_DESC_ON_STACK(shash, tfm->polyval);
112 	__le64 tweak_length_block[2];
113 	int err;
114 
115 	shash->tfm = tctx->polyval;
116 	memset(tweak_length_block, 0, sizeof(tweak_length_block));
117 
118 	tweak_length_block[0] = cpu_to_le64(TWEAK_SIZE * 8 * 2 + 2 + has_remainder);
119 	err = crypto_shash_init(shash);
120 	if (err)
121 		return err;
122 	err = crypto_shash_update(shash, (u8 *)tweak_length_block,
123 				  POLYVAL_BLOCK_SIZE);
124 	if (err)
125 		return err;
126 	return crypto_shash_export(shash, hctr2_hashed_tweaklen(tctx, has_remainder));
127 }
128 
hctr2_setkey(struct crypto_skcipher * tfm,const u8 * key,unsigned int keylen)129 static int hctr2_setkey(struct crypto_skcipher *tfm, const u8 *key,
130 			unsigned int keylen)
131 {
132 	struct hctr2_tfm_ctx *tctx = crypto_skcipher_ctx(tfm);
133 	u8 hbar[BLOCKCIPHER_BLOCK_SIZE];
134 	int err;
135 
136 	crypto_cipher_clear_flags(tctx->blockcipher, CRYPTO_TFM_REQ_MASK);
137 	crypto_cipher_set_flags(tctx->blockcipher,
138 				crypto_skcipher_get_flags(tfm) &
139 				CRYPTO_TFM_REQ_MASK);
140 	err = crypto_cipher_setkey(tctx->blockcipher, key, keylen);
141 	if (err)
142 		return err;
143 
144 	crypto_skcipher_clear_flags(tctx->xctr, CRYPTO_TFM_REQ_MASK);
145 	crypto_skcipher_set_flags(tctx->xctr,
146 				  crypto_skcipher_get_flags(tfm) &
147 				  CRYPTO_TFM_REQ_MASK);
148 	err = crypto_skcipher_setkey(tctx->xctr, key, keylen);
149 	if (err)
150 		return err;
151 
152 	memset(hbar, 0, sizeof(hbar));
153 	crypto_cipher_encrypt_one(tctx->blockcipher, hbar, hbar);
154 
155 	memset(tctx->L, 0, sizeof(tctx->L));
156 	tctx->L[0] = 0x01;
157 	crypto_cipher_encrypt_one(tctx->blockcipher, tctx->L, tctx->L);
158 
159 	crypto_shash_clear_flags(tctx->polyval, CRYPTO_TFM_REQ_MASK);
160 	crypto_shash_set_flags(tctx->polyval, crypto_skcipher_get_flags(tfm) &
161 			       CRYPTO_TFM_REQ_MASK);
162 	err = crypto_shash_setkey(tctx->polyval, hbar, BLOCKCIPHER_BLOCK_SIZE);
163 	if (err)
164 		return err;
165 	memzero_explicit(hbar, sizeof(hbar));
166 
167 	return hctr2_hash_tweaklen(tctx, true) ?: hctr2_hash_tweaklen(tctx, false);
168 }
169 
hctr2_hash_tweak(struct skcipher_request * req)170 static int hctr2_hash_tweak(struct skcipher_request *req)
171 {
172 	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
173 	const struct hctr2_tfm_ctx *tctx = crypto_skcipher_ctx(tfm);
174 	struct hctr2_request_ctx *rctx = skcipher_request_ctx(req);
175 	struct shash_desc *hash_desc = &rctx->u.hash_desc;
176 	int err;
177 	bool has_remainder = req->cryptlen % POLYVAL_BLOCK_SIZE;
178 
179 	hash_desc->tfm = tctx->polyval;
180 	err = crypto_shash_import(hash_desc, hctr2_hashed_tweaklen(tctx, has_remainder));
181 	if (err)
182 		return err;
183 	err = crypto_shash_update(hash_desc, req->iv, TWEAK_SIZE);
184 	if (err)
185 		return err;
186 
187 	// Store the hashed tweak, since we need it when computing both
188 	// H(T || N) and H(T || V).
189 	return crypto_shash_export(hash_desc, hctr2_hashed_tweak(tctx, rctx));
190 }
191 
hctr2_hash_message(struct skcipher_request * req,struct scatterlist * sgl,u8 digest[POLYVAL_DIGEST_SIZE])192 static int hctr2_hash_message(struct skcipher_request *req,
193 			      struct scatterlist *sgl,
194 			      u8 digest[POLYVAL_DIGEST_SIZE])
195 {
196 	static const u8 padding[BLOCKCIPHER_BLOCK_SIZE] = { 0x1 };
197 	struct hctr2_request_ctx *rctx = skcipher_request_ctx(req);
198 	struct shash_desc *hash_desc = &rctx->u.hash_desc;
199 	const unsigned int bulk_len = req->cryptlen - BLOCKCIPHER_BLOCK_SIZE;
200 	struct sg_mapping_iter miter;
201 	unsigned int remainder = bulk_len % BLOCKCIPHER_BLOCK_SIZE;
202 	int i;
203 	int err = 0;
204 	int n = 0;
205 
206 	sg_miter_start(&miter, sgl, sg_nents(sgl),
207 		       SG_MITER_FROM_SG | SG_MITER_ATOMIC);
208 	for (i = 0; i < bulk_len; i += n) {
209 		sg_miter_next(&miter);
210 		n = min_t(unsigned int, miter.length, bulk_len - i);
211 		err = crypto_shash_update(hash_desc, miter.addr, n);
212 		if (err)
213 			break;
214 	}
215 	sg_miter_stop(&miter);
216 
217 	if (err)
218 		return err;
219 
220 	if (remainder) {
221 		err = crypto_shash_update(hash_desc, padding,
222 					  BLOCKCIPHER_BLOCK_SIZE - remainder);
223 		if (err)
224 			return err;
225 	}
226 	return crypto_shash_final(hash_desc, digest);
227 }
228 
hctr2_finish(struct skcipher_request * req)229 static int hctr2_finish(struct skcipher_request *req)
230 {
231 	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
232 	const struct hctr2_tfm_ctx *tctx = crypto_skcipher_ctx(tfm);
233 	struct hctr2_request_ctx *rctx = skcipher_request_ctx(req);
234 	u8 digest[POLYVAL_DIGEST_SIZE];
235 	struct shash_desc *hash_desc = &rctx->u.hash_desc;
236 	int err;
237 
238 	// U = UU ^ H(T || V)
239 	// or M = MM ^ H(T || N)
240 	hash_desc->tfm = tctx->polyval;
241 	err = crypto_shash_import(hash_desc, hctr2_hashed_tweak(tctx, rctx));
242 	if (err)
243 		return err;
244 	err = hctr2_hash_message(req, rctx->bulk_part_dst, digest);
245 	if (err)
246 		return err;
247 	crypto_xor(rctx->first_block, digest, BLOCKCIPHER_BLOCK_SIZE);
248 
249 	// Copy U (or M) into dst scatterlist
250 	scatterwalk_map_and_copy(rctx->first_block, req->dst,
251 				 0, BLOCKCIPHER_BLOCK_SIZE, 1);
252 	return 0;
253 }
254 
hctr2_xctr_done(void * data,int err)255 static void hctr2_xctr_done(void *data, int err)
256 {
257 	struct skcipher_request *req = data;
258 
259 	if (!err)
260 		err = hctr2_finish(req);
261 
262 	skcipher_request_complete(req, err);
263 }
264 
hctr2_crypt(struct skcipher_request * req,bool enc)265 static int hctr2_crypt(struct skcipher_request *req, bool enc)
266 {
267 	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
268 	const struct hctr2_tfm_ctx *tctx = crypto_skcipher_ctx(tfm);
269 	struct hctr2_request_ctx *rctx = skcipher_request_ctx(req);
270 	u8 digest[POLYVAL_DIGEST_SIZE];
271 	int bulk_len = req->cryptlen - BLOCKCIPHER_BLOCK_SIZE;
272 	int err;
273 
274 	// Requests must be at least one block
275 	if (req->cryptlen < BLOCKCIPHER_BLOCK_SIZE)
276 		return -EINVAL;
277 
278 	// Copy M (or U) into a temporary buffer
279 	scatterwalk_map_and_copy(rctx->first_block, req->src,
280 				 0, BLOCKCIPHER_BLOCK_SIZE, 0);
281 
282 	// Create scatterlists for N and V
283 	rctx->bulk_part_src = scatterwalk_ffwd(rctx->sg_src, req->src,
284 					       BLOCKCIPHER_BLOCK_SIZE);
285 	rctx->bulk_part_dst = scatterwalk_ffwd(rctx->sg_dst, req->dst,
286 					       BLOCKCIPHER_BLOCK_SIZE);
287 
288 	// MM = M ^ H(T || N)
289 	// or UU = U ^ H(T || V)
290 	err = hctr2_hash_tweak(req);
291 	if (err)
292 		return err;
293 	err = hctr2_hash_message(req, rctx->bulk_part_src, digest);
294 	if (err)
295 		return err;
296 	crypto_xor(digest, rctx->first_block, BLOCKCIPHER_BLOCK_SIZE);
297 
298 	// UU = E(MM)
299 	// or MM = D(UU)
300 	if (enc)
301 		crypto_cipher_encrypt_one(tctx->blockcipher, rctx->first_block,
302 					  digest);
303 	else
304 		crypto_cipher_decrypt_one(tctx->blockcipher, rctx->first_block,
305 					  digest);
306 
307 	// S = MM ^ UU ^ L
308 	crypto_xor(digest, rctx->first_block, BLOCKCIPHER_BLOCK_SIZE);
309 	crypto_xor_cpy(rctx->xctr_iv, digest, tctx->L, BLOCKCIPHER_BLOCK_SIZE);
310 
311 	// V = XCTR(S, N)
312 	// or N = XCTR(S, V)
313 	skcipher_request_set_tfm(&rctx->u.xctr_req, tctx->xctr);
314 	skcipher_request_set_crypt(&rctx->u.xctr_req, rctx->bulk_part_src,
315 				   rctx->bulk_part_dst, bulk_len,
316 				   rctx->xctr_iv);
317 	skcipher_request_set_callback(&rctx->u.xctr_req,
318 				      req->base.flags,
319 				      hctr2_xctr_done, req);
320 	return crypto_skcipher_encrypt(&rctx->u.xctr_req) ?:
321 		hctr2_finish(req);
322 }
323 
hctr2_encrypt(struct skcipher_request * req)324 static int hctr2_encrypt(struct skcipher_request *req)
325 {
326 	return hctr2_crypt(req, true);
327 }
328 
hctr2_decrypt(struct skcipher_request * req)329 static int hctr2_decrypt(struct skcipher_request *req)
330 {
331 	return hctr2_crypt(req, false);
332 }
333 
hctr2_init_tfm(struct crypto_skcipher * tfm)334 static int hctr2_init_tfm(struct crypto_skcipher *tfm)
335 {
336 	struct skcipher_instance *inst = skcipher_alg_instance(tfm);
337 	struct hctr2_instance_ctx *ictx = skcipher_instance_ctx(inst);
338 	struct hctr2_tfm_ctx *tctx = crypto_skcipher_ctx(tfm);
339 	struct crypto_skcipher *xctr;
340 	struct crypto_cipher *blockcipher;
341 	struct crypto_shash *polyval;
342 	unsigned int subreq_size;
343 	int err;
344 
345 	xctr = crypto_spawn_skcipher(&ictx->xctr_spawn);
346 	if (IS_ERR(xctr))
347 		return PTR_ERR(xctr);
348 
349 	blockcipher = crypto_spawn_cipher(&ictx->blockcipher_spawn);
350 	if (IS_ERR(blockcipher)) {
351 		err = PTR_ERR(blockcipher);
352 		goto err_free_xctr;
353 	}
354 
355 	polyval = crypto_spawn_shash(&ictx->polyval_spawn);
356 	if (IS_ERR(polyval)) {
357 		err = PTR_ERR(polyval);
358 		goto err_free_blockcipher;
359 	}
360 
361 	tctx->xctr = xctr;
362 	tctx->blockcipher = blockcipher;
363 	tctx->polyval = polyval;
364 
365 	BUILD_BUG_ON(offsetofend(struct hctr2_request_ctx, u) !=
366 				 sizeof(struct hctr2_request_ctx));
367 	subreq_size = max(sizeof_field(struct hctr2_request_ctx, u.hash_desc) +
368 			  crypto_shash_descsize(polyval),
369 			  sizeof_field(struct hctr2_request_ctx, u.xctr_req) +
370 			  crypto_skcipher_reqsize(xctr));
371 
372 	tctx->hashed_tweak_offset = offsetof(struct hctr2_request_ctx, u) +
373 				    subreq_size;
374 	crypto_skcipher_set_reqsize(tfm, tctx->hashed_tweak_offset +
375 				    crypto_shash_statesize(polyval));
376 	return 0;
377 
378 err_free_blockcipher:
379 	crypto_free_cipher(blockcipher);
380 err_free_xctr:
381 	crypto_free_skcipher(xctr);
382 	return err;
383 }
384 
hctr2_exit_tfm(struct crypto_skcipher * tfm)385 static void hctr2_exit_tfm(struct crypto_skcipher *tfm)
386 {
387 	struct hctr2_tfm_ctx *tctx = crypto_skcipher_ctx(tfm);
388 
389 	crypto_free_cipher(tctx->blockcipher);
390 	crypto_free_skcipher(tctx->xctr);
391 	crypto_free_shash(tctx->polyval);
392 }
393 
hctr2_free_instance(struct skcipher_instance * inst)394 static void hctr2_free_instance(struct skcipher_instance *inst)
395 {
396 	struct hctr2_instance_ctx *ictx = skcipher_instance_ctx(inst);
397 
398 	crypto_drop_cipher(&ictx->blockcipher_spawn);
399 	crypto_drop_skcipher(&ictx->xctr_spawn);
400 	crypto_drop_shash(&ictx->polyval_spawn);
401 	kfree(inst);
402 }
403 
hctr2_create_common(struct crypto_template * tmpl,struct rtattr ** tb,const char * xctr_name,const char * polyval_name)404 static int hctr2_create_common(struct crypto_template *tmpl,
405 			       struct rtattr **tb,
406 			       const char *xctr_name,
407 			       const char *polyval_name)
408 {
409 	u32 mask;
410 	struct skcipher_instance *inst;
411 	struct hctr2_instance_ctx *ictx;
412 	struct skcipher_alg *xctr_alg;
413 	struct crypto_alg *blockcipher_alg;
414 	struct shash_alg *polyval_alg;
415 	char blockcipher_name[CRYPTO_MAX_ALG_NAME];
416 	int len;
417 	int err;
418 
419 	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SKCIPHER, &mask);
420 	if (err)
421 		return err;
422 
423 	inst = kzalloc(sizeof(*inst) + sizeof(*ictx), GFP_KERNEL);
424 	if (!inst)
425 		return -ENOMEM;
426 	ictx = skcipher_instance_ctx(inst);
427 
428 	/* Stream cipher, xctr(block_cipher) */
429 	err = crypto_grab_skcipher(&ictx->xctr_spawn,
430 				   skcipher_crypto_instance(inst),
431 				   xctr_name, 0, mask);
432 	if (err)
433 		goto err_free_inst;
434 	xctr_alg = crypto_spawn_skcipher_alg(&ictx->xctr_spawn);
435 
436 	err = -EINVAL;
437 	if (strncmp(xctr_alg->base.cra_name, "xctr(", 5))
438 		goto err_free_inst;
439 	len = strscpy(blockcipher_name, xctr_alg->base.cra_name + 5,
440 		      sizeof(blockcipher_name));
441 	if (len < 1)
442 		goto err_free_inst;
443 	if (blockcipher_name[len - 1] != ')')
444 		goto err_free_inst;
445 	blockcipher_name[len - 1] = 0;
446 
447 	/* Block cipher, e.g. "aes" */
448 	err = crypto_grab_cipher(&ictx->blockcipher_spawn,
449 				 skcipher_crypto_instance(inst),
450 				 blockcipher_name, 0, mask);
451 	if (err)
452 		goto err_free_inst;
453 	blockcipher_alg = crypto_spawn_cipher_alg(&ictx->blockcipher_spawn);
454 
455 	/* Require blocksize of 16 bytes */
456 	err = -EINVAL;
457 	if (blockcipher_alg->cra_blocksize != BLOCKCIPHER_BLOCK_SIZE)
458 		goto err_free_inst;
459 
460 	/* Polyval ε-∆U hash function */
461 	err = crypto_grab_shash(&ictx->polyval_spawn,
462 				skcipher_crypto_instance(inst),
463 				polyval_name, 0, mask);
464 	if (err)
465 		goto err_free_inst;
466 	polyval_alg = crypto_spawn_shash_alg(&ictx->polyval_spawn);
467 
468 	/* Ensure Polyval is being used */
469 	err = -EINVAL;
470 	if (strcmp(polyval_alg->base.cra_name, "polyval") != 0)
471 		goto err_free_inst;
472 
473 	/* Instance fields */
474 
475 	err = -ENAMETOOLONG;
476 	if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME, "hctr2(%s)",
477 		     blockcipher_alg->cra_name) >= CRYPTO_MAX_ALG_NAME)
478 		goto err_free_inst;
479 	if (snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME,
480 		     "hctr2_base(%s,%s)",
481 		     xctr_alg->base.cra_driver_name,
482 		     polyval_alg->base.cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
483 		goto err_free_inst;
484 
485 	inst->alg.base.cra_blocksize = BLOCKCIPHER_BLOCK_SIZE;
486 	inst->alg.base.cra_ctxsize = sizeof(struct hctr2_tfm_ctx) +
487 				     polyval_alg->statesize * 2;
488 	inst->alg.base.cra_alignmask = xctr_alg->base.cra_alignmask |
489 				       polyval_alg->base.cra_alignmask;
490 	/*
491 	 * The hash function is called twice, so it is weighted higher than the
492 	 * xctr and blockcipher.
493 	 */
494 	inst->alg.base.cra_priority = (2 * xctr_alg->base.cra_priority +
495 				       4 * polyval_alg->base.cra_priority +
496 				       blockcipher_alg->cra_priority) / 7;
497 
498 	inst->alg.setkey = hctr2_setkey;
499 	inst->alg.encrypt = hctr2_encrypt;
500 	inst->alg.decrypt = hctr2_decrypt;
501 	inst->alg.init = hctr2_init_tfm;
502 	inst->alg.exit = hctr2_exit_tfm;
503 	inst->alg.min_keysize = crypto_skcipher_alg_min_keysize(xctr_alg);
504 	inst->alg.max_keysize = crypto_skcipher_alg_max_keysize(xctr_alg);
505 	inst->alg.ivsize = TWEAK_SIZE;
506 
507 	inst->free = hctr2_free_instance;
508 
509 	err = skcipher_register_instance(tmpl, inst);
510 	if (err) {
511 err_free_inst:
512 		hctr2_free_instance(inst);
513 	}
514 	return err;
515 }
516 
hctr2_create_base(struct crypto_template * tmpl,struct rtattr ** tb)517 static int hctr2_create_base(struct crypto_template *tmpl, struct rtattr **tb)
518 {
519 	const char *xctr_name;
520 	const char *polyval_name;
521 
522 	xctr_name = crypto_attr_alg_name(tb[1]);
523 	if (IS_ERR(xctr_name))
524 		return PTR_ERR(xctr_name);
525 
526 	polyval_name = crypto_attr_alg_name(tb[2]);
527 	if (IS_ERR(polyval_name))
528 		return PTR_ERR(polyval_name);
529 
530 	return hctr2_create_common(tmpl, tb, xctr_name, polyval_name);
531 }
532 
hctr2_create(struct crypto_template * tmpl,struct rtattr ** tb)533 static int hctr2_create(struct crypto_template *tmpl, struct rtattr **tb)
534 {
535 	const char *blockcipher_name;
536 	char xctr_name[CRYPTO_MAX_ALG_NAME];
537 
538 	blockcipher_name = crypto_attr_alg_name(tb[1]);
539 	if (IS_ERR(blockcipher_name))
540 		return PTR_ERR(blockcipher_name);
541 
542 	if (snprintf(xctr_name, CRYPTO_MAX_ALG_NAME, "xctr(%s)",
543 		    blockcipher_name) >= CRYPTO_MAX_ALG_NAME)
544 		return -ENAMETOOLONG;
545 
546 	return hctr2_create_common(tmpl, tb, xctr_name, "polyval");
547 }
548 
549 static struct crypto_template hctr2_tmpls[] = {
550 	{
551 		/* hctr2_base(xctr_name, polyval_name) */
552 		.name = "hctr2_base",
553 		.create = hctr2_create_base,
554 		.module = THIS_MODULE,
555 	}, {
556 		/* hctr2(blockcipher_name) */
557 		.name = "hctr2",
558 		.create = hctr2_create,
559 		.module = THIS_MODULE,
560 	}
561 };
562 
hctr2_module_init(void)563 static int __init hctr2_module_init(void)
564 {
565 	return crypto_register_templates(hctr2_tmpls, ARRAY_SIZE(hctr2_tmpls));
566 }
567 
hctr2_module_exit(void)568 static void __exit hctr2_module_exit(void)
569 {
570 	return crypto_unregister_templates(hctr2_tmpls,
571 					   ARRAY_SIZE(hctr2_tmpls));
572 }
573 
574 subsys_initcall(hctr2_module_init);
575 module_exit(hctr2_module_exit);
576 
577 MODULE_DESCRIPTION("HCTR2 length-preserving encryption mode");
578 MODULE_LICENSE("GPL v2");
579 MODULE_ALIAS_CRYPTO("hctr2");
580 MODULE_IMPORT_NS(CRYPTO_INTERNAL);
581