1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Adiantum length-preserving encryption mode
4 *
5 * Copyright 2018 Google LLC
6 */
7
8 /*
9 * Adiantum is a tweakable, length-preserving encryption mode designed for fast
10 * and secure disk encryption, especially on CPUs without dedicated crypto
11 * instructions. Adiantum encrypts each sector using the XChaCha12 stream
12 * cipher, two passes of an ε-almost-∆-universal (ε-∆U) hash function based on
13 * NH and Poly1305, and an invocation of the AES-256 block cipher on a single
14 * 16-byte block. See the paper for details:
15 *
16 * Adiantum: length-preserving encryption for entry-level processors
17 * (https://eprint.iacr.org/2018/720.pdf)
18 *
19 * For flexibility, this implementation also allows other ciphers:
20 *
21 * - Stream cipher: XChaCha12 or XChaCha20
22 * - Block cipher: any with a 128-bit block size and 256-bit key
23 *
24 * This implementation doesn't currently allow other ε-∆U hash functions, i.e.
25 * HPolyC is not supported. This is because Adiantum is ~20% faster than HPolyC
26 * but still provably as secure, and also the ε-∆U hash function of HBSH is
27 * formally defined to take two inputs (tweak, message) which makes it difficult
28 * to wrap with the crypto_shash API. Rather, some details need to be handled
29 * here. Nevertheless, if needed in the future, support for other ε-∆U hash
30 * functions could be added here.
31 */
32
33 #include <crypto/b128ops.h>
34 #include <crypto/chacha.h>
35 #include <crypto/internal/cipher.h>
36 #include <crypto/internal/hash.h>
37 #include <crypto/internal/poly1305.h>
38 #include <crypto/internal/skcipher.h>
39 #include <crypto/nhpoly1305.h>
40 #include <crypto/scatterwalk.h>
41 #include <linux/module.h>
42
43 /*
44 * Size of right-hand part of input data, in bytes; also the size of the block
45 * cipher's block size and the hash function's output.
46 */
47 #define BLOCKCIPHER_BLOCK_SIZE 16
48
49 /* Size of the block cipher key (K_E) in bytes */
50 #define BLOCKCIPHER_KEY_SIZE 32
51
52 /* Size of the hash key (K_H) in bytes */
53 #define HASH_KEY_SIZE (POLY1305_BLOCK_SIZE + NHPOLY1305_KEY_SIZE)
54
55 /*
56 * The specification allows variable-length tweaks, but Linux's crypto API
57 * currently only allows algorithms to support a single length. The "natural"
58 * tweak length for Adiantum is 16, since that fits into one Poly1305 block for
59 * the best performance. But longer tweaks are useful for fscrypt, to avoid
60 * needing to derive per-file keys. So instead we use two blocks, or 32 bytes.
61 */
62 #define TWEAK_SIZE 32
63
64 struct adiantum_instance_ctx {
65 struct crypto_skcipher_spawn streamcipher_spawn;
66 struct crypto_cipher_spawn blockcipher_spawn;
67 struct crypto_shash_spawn hash_spawn;
68 };
69
70 struct adiantum_tfm_ctx {
71 struct crypto_skcipher *streamcipher;
72 struct crypto_cipher *blockcipher;
73 struct crypto_shash *hash;
74 struct poly1305_core_key header_hash_key;
75 };
76
77 struct adiantum_request_ctx {
78
79 /*
80 * Buffer for right-hand part of data, i.e.
81 *
82 * P_L => P_M => C_M => C_R when encrypting, or
83 * C_R => C_M => P_M => P_L when decrypting.
84 *
85 * Also used to build the IV for the stream cipher.
86 */
87 union {
88 u8 bytes[XCHACHA_IV_SIZE];
89 __le32 words[XCHACHA_IV_SIZE / sizeof(__le32)];
90 le128 bignum; /* interpret as element of Z/(2^{128}Z) */
91 } rbuf;
92
93 bool enc; /* true if encrypting, false if decrypting */
94
95 /*
96 * The result of the Poly1305 ε-∆U hash function applied to
97 * (bulk length, tweak)
98 */
99 le128 header_hash;
100
101 /* Sub-requests, must be last */
102 union {
103 struct shash_desc hash_desc;
104 struct skcipher_request streamcipher_req;
105 } u;
106 };
107
108 /*
109 * Given the XChaCha stream key K_S, derive the block cipher key K_E and the
110 * hash key K_H as follows:
111 *
112 * K_E || K_H || ... = XChaCha(key=K_S, nonce=1||0^191)
113 *
114 * Note that this denotes using bits from the XChaCha keystream, which here we
115 * get indirectly by encrypting a buffer containing all 0's.
116 */
adiantum_setkey(struct crypto_skcipher * tfm,const u8 * key,unsigned int keylen)117 static int adiantum_setkey(struct crypto_skcipher *tfm, const u8 *key,
118 unsigned int keylen)
119 {
120 struct adiantum_tfm_ctx *tctx = crypto_skcipher_ctx(tfm);
121 struct {
122 u8 iv[XCHACHA_IV_SIZE];
123 u8 derived_keys[BLOCKCIPHER_KEY_SIZE + HASH_KEY_SIZE];
124 struct scatterlist sg;
125 struct crypto_wait wait;
126 struct skcipher_request req; /* must be last */
127 } *data;
128 u8 *keyp;
129 int err;
130
131 /* Set the stream cipher key (K_S) */
132 crypto_skcipher_clear_flags(tctx->streamcipher, CRYPTO_TFM_REQ_MASK);
133 crypto_skcipher_set_flags(tctx->streamcipher,
134 crypto_skcipher_get_flags(tfm) &
135 CRYPTO_TFM_REQ_MASK);
136 err = crypto_skcipher_setkey(tctx->streamcipher, key, keylen);
137 if (err)
138 return err;
139
140 /* Derive the subkeys */
141 data = kzalloc(sizeof(*data) +
142 crypto_skcipher_reqsize(tctx->streamcipher), GFP_KERNEL);
143 if (!data)
144 return -ENOMEM;
145 data->iv[0] = 1;
146 sg_init_one(&data->sg, data->derived_keys, sizeof(data->derived_keys));
147 crypto_init_wait(&data->wait);
148 skcipher_request_set_tfm(&data->req, tctx->streamcipher);
149 skcipher_request_set_callback(&data->req, CRYPTO_TFM_REQ_MAY_SLEEP |
150 CRYPTO_TFM_REQ_MAY_BACKLOG,
151 crypto_req_done, &data->wait);
152 skcipher_request_set_crypt(&data->req, &data->sg, &data->sg,
153 sizeof(data->derived_keys), data->iv);
154 err = crypto_wait_req(crypto_skcipher_encrypt(&data->req), &data->wait);
155 if (err)
156 goto out;
157 keyp = data->derived_keys;
158
159 /* Set the block cipher key (K_E) */
160 crypto_cipher_clear_flags(tctx->blockcipher, CRYPTO_TFM_REQ_MASK);
161 crypto_cipher_set_flags(tctx->blockcipher,
162 crypto_skcipher_get_flags(tfm) &
163 CRYPTO_TFM_REQ_MASK);
164 err = crypto_cipher_setkey(tctx->blockcipher, keyp,
165 BLOCKCIPHER_KEY_SIZE);
166 if (err)
167 goto out;
168 keyp += BLOCKCIPHER_KEY_SIZE;
169
170 /* Set the hash key (K_H) */
171 poly1305_core_setkey(&tctx->header_hash_key, keyp);
172 keyp += POLY1305_BLOCK_SIZE;
173
174 crypto_shash_clear_flags(tctx->hash, CRYPTO_TFM_REQ_MASK);
175 crypto_shash_set_flags(tctx->hash, crypto_skcipher_get_flags(tfm) &
176 CRYPTO_TFM_REQ_MASK);
177 err = crypto_shash_setkey(tctx->hash, keyp, NHPOLY1305_KEY_SIZE);
178 keyp += NHPOLY1305_KEY_SIZE;
179 WARN_ON(keyp != &data->derived_keys[ARRAY_SIZE(data->derived_keys)]);
180 out:
181 kfree_sensitive(data);
182 return err;
183 }
184
185 /* Addition in Z/(2^{128}Z) */
le128_add(le128 * r,const le128 * v1,const le128 * v2)186 static inline void le128_add(le128 *r, const le128 *v1, const le128 *v2)
187 {
188 u64 x = le64_to_cpu(v1->b);
189 u64 y = le64_to_cpu(v2->b);
190
191 r->b = cpu_to_le64(x + y);
192 r->a = cpu_to_le64(le64_to_cpu(v1->a) + le64_to_cpu(v2->a) +
193 (x + y < x));
194 }
195
196 /* Subtraction in Z/(2^{128}Z) */
le128_sub(le128 * r,const le128 * v1,const le128 * v2)197 static inline void le128_sub(le128 *r, const le128 *v1, const le128 *v2)
198 {
199 u64 x = le64_to_cpu(v1->b);
200 u64 y = le64_to_cpu(v2->b);
201
202 r->b = cpu_to_le64(x - y);
203 r->a = cpu_to_le64(le64_to_cpu(v1->a) - le64_to_cpu(v2->a) -
204 (x - y > x));
205 }
206
207 /*
208 * Apply the Poly1305 ε-∆U hash function to (bulk length, tweak) and save the
209 * result to rctx->header_hash. This is the calculation
210 *
211 * H_T ← Poly1305_{K_T}(bin_{128}(|L|) || T)
212 *
213 * from the procedure in section 6.4 of the Adiantum paper. The resulting value
214 * is reused in both the first and second hash steps. Specifically, it's added
215 * to the result of an independently keyed ε-∆U hash function (for equal length
216 * inputs only) taken over the left-hand part (the "bulk") of the message, to
217 * give the overall Adiantum hash of the (tweak, left-hand part) pair.
218 */
adiantum_hash_header(struct skcipher_request * req)219 static void adiantum_hash_header(struct skcipher_request *req)
220 {
221 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
222 const struct adiantum_tfm_ctx *tctx = crypto_skcipher_ctx(tfm);
223 struct adiantum_request_ctx *rctx = skcipher_request_ctx(req);
224 const unsigned int bulk_len = req->cryptlen - BLOCKCIPHER_BLOCK_SIZE;
225 struct {
226 __le64 message_bits;
227 __le64 padding;
228 } header = {
229 .message_bits = cpu_to_le64((u64)bulk_len * 8)
230 };
231 struct poly1305_state state;
232
233 poly1305_core_init(&state);
234
235 BUILD_BUG_ON(sizeof(header) % POLY1305_BLOCK_SIZE != 0);
236 poly1305_core_blocks(&state, &tctx->header_hash_key,
237 &header, sizeof(header) / POLY1305_BLOCK_SIZE, 1);
238
239 BUILD_BUG_ON(TWEAK_SIZE % POLY1305_BLOCK_SIZE != 0);
240 poly1305_core_blocks(&state, &tctx->header_hash_key, req->iv,
241 TWEAK_SIZE / POLY1305_BLOCK_SIZE, 1);
242
243 poly1305_core_emit(&state, NULL, &rctx->header_hash);
244 }
245
246 /* Hash the left-hand part (the "bulk") of the message using NHPoly1305 */
adiantum_hash_message(struct skcipher_request * req,struct scatterlist * sgl,le128 * digest)247 static int adiantum_hash_message(struct skcipher_request *req,
248 struct scatterlist *sgl, le128 *digest)
249 {
250 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
251 const struct adiantum_tfm_ctx *tctx = crypto_skcipher_ctx(tfm);
252 struct adiantum_request_ctx *rctx = skcipher_request_ctx(req);
253 const unsigned int bulk_len = req->cryptlen - BLOCKCIPHER_BLOCK_SIZE;
254 struct shash_desc *hash_desc = &rctx->u.hash_desc;
255 struct sg_mapping_iter miter;
256 unsigned int i, n;
257 int err;
258
259 hash_desc->tfm = tctx->hash;
260
261 err = crypto_shash_init(hash_desc);
262 if (err)
263 return err;
264
265 sg_miter_start(&miter, sgl, sg_nents(sgl),
266 SG_MITER_FROM_SG | SG_MITER_ATOMIC);
267 for (i = 0; i < bulk_len; i += n) {
268 sg_miter_next(&miter);
269 n = min_t(unsigned int, miter.length, bulk_len - i);
270 err = crypto_shash_update(hash_desc, miter.addr, n);
271 if (err)
272 break;
273 }
274 sg_miter_stop(&miter);
275 if (err)
276 return err;
277
278 return crypto_shash_final(hash_desc, (u8 *)digest);
279 }
280
281 /* Continue Adiantum encryption/decryption after the stream cipher step */
adiantum_finish(struct skcipher_request * req)282 static int adiantum_finish(struct skcipher_request *req)
283 {
284 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
285 const struct adiantum_tfm_ctx *tctx = crypto_skcipher_ctx(tfm);
286 struct adiantum_request_ctx *rctx = skcipher_request_ctx(req);
287 const unsigned int bulk_len = req->cryptlen - BLOCKCIPHER_BLOCK_SIZE;
288 le128 digest;
289 int err;
290
291 /* If decrypting, decrypt C_M with the block cipher to get P_M */
292 if (!rctx->enc)
293 crypto_cipher_decrypt_one(tctx->blockcipher, rctx->rbuf.bytes,
294 rctx->rbuf.bytes);
295
296 /*
297 * Second hash step
298 * enc: C_R = C_M - H_{K_H}(T, C_L)
299 * dec: P_R = P_M - H_{K_H}(T, P_L)
300 */
301 err = adiantum_hash_message(req, req->dst, &digest);
302 if (err)
303 return err;
304 le128_add(&digest, &digest, &rctx->header_hash);
305 le128_sub(&rctx->rbuf.bignum, &rctx->rbuf.bignum, &digest);
306 scatterwalk_map_and_copy(&rctx->rbuf.bignum, req->dst,
307 bulk_len, BLOCKCIPHER_BLOCK_SIZE, 1);
308 return 0;
309 }
310
adiantum_streamcipher_done(struct crypto_async_request * areq,int err)311 static void adiantum_streamcipher_done(struct crypto_async_request *areq,
312 int err)
313 {
314 struct skcipher_request *req = areq->data;
315
316 if (!err)
317 err = adiantum_finish(req);
318
319 skcipher_request_complete(req, err);
320 }
321
adiantum_crypt(struct skcipher_request * req,bool enc)322 static int adiantum_crypt(struct skcipher_request *req, bool enc)
323 {
324 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
325 const struct adiantum_tfm_ctx *tctx = crypto_skcipher_ctx(tfm);
326 struct adiantum_request_ctx *rctx = skcipher_request_ctx(req);
327 const unsigned int bulk_len = req->cryptlen - BLOCKCIPHER_BLOCK_SIZE;
328 unsigned int stream_len;
329 le128 digest;
330 int err;
331
332 if (req->cryptlen < BLOCKCIPHER_BLOCK_SIZE)
333 return -EINVAL;
334
335 rctx->enc = enc;
336
337 /*
338 * First hash step
339 * enc: P_M = P_R + H_{K_H}(T, P_L)
340 * dec: C_M = C_R + H_{K_H}(T, C_L)
341 */
342 adiantum_hash_header(req);
343 err = adiantum_hash_message(req, req->src, &digest);
344 if (err)
345 return err;
346 le128_add(&digest, &digest, &rctx->header_hash);
347 scatterwalk_map_and_copy(&rctx->rbuf.bignum, req->src,
348 bulk_len, BLOCKCIPHER_BLOCK_SIZE, 0);
349 le128_add(&rctx->rbuf.bignum, &rctx->rbuf.bignum, &digest);
350
351 /* If encrypting, encrypt P_M with the block cipher to get C_M */
352 if (enc)
353 crypto_cipher_encrypt_one(tctx->blockcipher, rctx->rbuf.bytes,
354 rctx->rbuf.bytes);
355
356 /* Initialize the rest of the XChaCha IV (first part is C_M) */
357 BUILD_BUG_ON(BLOCKCIPHER_BLOCK_SIZE != 16);
358 BUILD_BUG_ON(XCHACHA_IV_SIZE != 32); /* nonce || stream position */
359 rctx->rbuf.words[4] = cpu_to_le32(1);
360 rctx->rbuf.words[5] = 0;
361 rctx->rbuf.words[6] = 0;
362 rctx->rbuf.words[7] = 0;
363
364 /*
365 * XChaCha needs to be done on all the data except the last 16 bytes;
366 * for disk encryption that usually means 4080 or 496 bytes. But ChaCha
367 * implementations tend to be most efficient when passed a whole number
368 * of 64-byte ChaCha blocks, or sometimes even a multiple of 256 bytes.
369 * And here it doesn't matter whether the last 16 bytes are written to,
370 * as the second hash step will overwrite them. Thus, round the XChaCha
371 * length up to the next 64-byte boundary if possible.
372 */
373 stream_len = bulk_len;
374 if (round_up(stream_len, CHACHA_BLOCK_SIZE) <= req->cryptlen)
375 stream_len = round_up(stream_len, CHACHA_BLOCK_SIZE);
376
377 skcipher_request_set_tfm(&rctx->u.streamcipher_req, tctx->streamcipher);
378 skcipher_request_set_crypt(&rctx->u.streamcipher_req, req->src,
379 req->dst, stream_len, &rctx->rbuf);
380 skcipher_request_set_callback(&rctx->u.streamcipher_req,
381 req->base.flags,
382 adiantum_streamcipher_done, req);
383 return crypto_skcipher_encrypt(&rctx->u.streamcipher_req) ?:
384 adiantum_finish(req);
385 }
386
adiantum_encrypt(struct skcipher_request * req)387 static int adiantum_encrypt(struct skcipher_request *req)
388 {
389 return adiantum_crypt(req, true);
390 }
391
adiantum_decrypt(struct skcipher_request * req)392 static int adiantum_decrypt(struct skcipher_request *req)
393 {
394 return adiantum_crypt(req, false);
395 }
396
adiantum_init_tfm(struct crypto_skcipher * tfm)397 static int adiantum_init_tfm(struct crypto_skcipher *tfm)
398 {
399 struct skcipher_instance *inst = skcipher_alg_instance(tfm);
400 struct adiantum_instance_ctx *ictx = skcipher_instance_ctx(inst);
401 struct adiantum_tfm_ctx *tctx = crypto_skcipher_ctx(tfm);
402 struct crypto_skcipher *streamcipher;
403 struct crypto_cipher *blockcipher;
404 struct crypto_shash *hash;
405 unsigned int subreq_size;
406 int err;
407
408 streamcipher = crypto_spawn_skcipher(&ictx->streamcipher_spawn);
409 if (IS_ERR(streamcipher))
410 return PTR_ERR(streamcipher);
411
412 blockcipher = crypto_spawn_cipher(&ictx->blockcipher_spawn);
413 if (IS_ERR(blockcipher)) {
414 err = PTR_ERR(blockcipher);
415 goto err_free_streamcipher;
416 }
417
418 hash = crypto_spawn_shash(&ictx->hash_spawn);
419 if (IS_ERR(hash)) {
420 err = PTR_ERR(hash);
421 goto err_free_blockcipher;
422 }
423
424 tctx->streamcipher = streamcipher;
425 tctx->blockcipher = blockcipher;
426 tctx->hash = hash;
427
428 BUILD_BUG_ON(offsetofend(struct adiantum_request_ctx, u) !=
429 sizeof(struct adiantum_request_ctx));
430 subreq_size = max(sizeof_field(struct adiantum_request_ctx,
431 u.hash_desc) +
432 crypto_shash_descsize(hash),
433 sizeof_field(struct adiantum_request_ctx,
434 u.streamcipher_req) +
435 crypto_skcipher_reqsize(streamcipher));
436
437 crypto_skcipher_set_reqsize(tfm,
438 offsetof(struct adiantum_request_ctx, u) +
439 subreq_size);
440 return 0;
441
442 err_free_blockcipher:
443 crypto_free_cipher(blockcipher);
444 err_free_streamcipher:
445 crypto_free_skcipher(streamcipher);
446 return err;
447 }
448
adiantum_exit_tfm(struct crypto_skcipher * tfm)449 static void adiantum_exit_tfm(struct crypto_skcipher *tfm)
450 {
451 struct adiantum_tfm_ctx *tctx = crypto_skcipher_ctx(tfm);
452
453 crypto_free_skcipher(tctx->streamcipher);
454 crypto_free_cipher(tctx->blockcipher);
455 crypto_free_shash(tctx->hash);
456 }
457
adiantum_free_instance(struct skcipher_instance * inst)458 static void adiantum_free_instance(struct skcipher_instance *inst)
459 {
460 struct adiantum_instance_ctx *ictx = skcipher_instance_ctx(inst);
461
462 crypto_drop_skcipher(&ictx->streamcipher_spawn);
463 crypto_drop_cipher(&ictx->blockcipher_spawn);
464 crypto_drop_shash(&ictx->hash_spawn);
465 kfree(inst);
466 }
467
468 /*
469 * Check for a supported set of inner algorithms.
470 * See the comment at the beginning of this file.
471 */
adiantum_supported_algorithms(struct skcipher_alg * streamcipher_alg,struct crypto_alg * blockcipher_alg,struct shash_alg * hash_alg)472 static bool adiantum_supported_algorithms(struct skcipher_alg *streamcipher_alg,
473 struct crypto_alg *blockcipher_alg,
474 struct shash_alg *hash_alg)
475 {
476 if (strcmp(streamcipher_alg->base.cra_name, "xchacha12") != 0 &&
477 strcmp(streamcipher_alg->base.cra_name, "xchacha20") != 0)
478 return false;
479
480 if (blockcipher_alg->cra_cipher.cia_min_keysize > BLOCKCIPHER_KEY_SIZE ||
481 blockcipher_alg->cra_cipher.cia_max_keysize < BLOCKCIPHER_KEY_SIZE)
482 return false;
483 if (blockcipher_alg->cra_blocksize != BLOCKCIPHER_BLOCK_SIZE)
484 return false;
485
486 if (strcmp(hash_alg->base.cra_name, "nhpoly1305") != 0)
487 return false;
488
489 return true;
490 }
491
adiantum_create(struct crypto_template * tmpl,struct rtattr ** tb)492 static int adiantum_create(struct crypto_template *tmpl, struct rtattr **tb)
493 {
494 u32 mask;
495 const char *nhpoly1305_name;
496 struct skcipher_instance *inst;
497 struct adiantum_instance_ctx *ictx;
498 struct skcipher_alg *streamcipher_alg;
499 struct crypto_alg *blockcipher_alg;
500 struct shash_alg *hash_alg;
501 int err;
502
503 err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SKCIPHER, &mask);
504 if (err)
505 return err;
506
507 inst = kzalloc(sizeof(*inst) + sizeof(*ictx), GFP_KERNEL);
508 if (!inst)
509 return -ENOMEM;
510 ictx = skcipher_instance_ctx(inst);
511
512 /* Stream cipher, e.g. "xchacha12" */
513 err = crypto_grab_skcipher(&ictx->streamcipher_spawn,
514 skcipher_crypto_instance(inst),
515 crypto_attr_alg_name(tb[1]), 0, mask);
516 if (err)
517 goto err_free_inst;
518 streamcipher_alg = crypto_spawn_skcipher_alg(&ictx->streamcipher_spawn);
519
520 /* Block cipher, e.g. "aes" */
521 err = crypto_grab_cipher(&ictx->blockcipher_spawn,
522 skcipher_crypto_instance(inst),
523 crypto_attr_alg_name(tb[2]), 0, mask);
524 if (err)
525 goto err_free_inst;
526 blockcipher_alg = crypto_spawn_cipher_alg(&ictx->blockcipher_spawn);
527
528 /* NHPoly1305 ε-∆U hash function */
529 nhpoly1305_name = crypto_attr_alg_name(tb[3]);
530 if (nhpoly1305_name == ERR_PTR(-ENOENT))
531 nhpoly1305_name = "nhpoly1305";
532 err = crypto_grab_shash(&ictx->hash_spawn,
533 skcipher_crypto_instance(inst),
534 nhpoly1305_name, 0, mask);
535 if (err)
536 goto err_free_inst;
537 hash_alg = crypto_spawn_shash_alg(&ictx->hash_spawn);
538
539 /* Check the set of algorithms */
540 if (!adiantum_supported_algorithms(streamcipher_alg, blockcipher_alg,
541 hash_alg)) {
542 pr_warn("Unsupported Adiantum instantiation: (%s,%s,%s)\n",
543 streamcipher_alg->base.cra_name,
544 blockcipher_alg->cra_name, hash_alg->base.cra_name);
545 err = -EINVAL;
546 goto err_free_inst;
547 }
548
549 /* Instance fields */
550
551 err = -ENAMETOOLONG;
552 if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
553 "adiantum(%s,%s)", streamcipher_alg->base.cra_name,
554 blockcipher_alg->cra_name) >= CRYPTO_MAX_ALG_NAME)
555 goto err_free_inst;
556 if (snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME,
557 "adiantum(%s,%s,%s)",
558 streamcipher_alg->base.cra_driver_name,
559 blockcipher_alg->cra_driver_name,
560 hash_alg->base.cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
561 goto err_free_inst;
562
563 inst->alg.base.cra_blocksize = BLOCKCIPHER_BLOCK_SIZE;
564 inst->alg.base.cra_ctxsize = sizeof(struct adiantum_tfm_ctx);
565 inst->alg.base.cra_alignmask = streamcipher_alg->base.cra_alignmask |
566 hash_alg->base.cra_alignmask;
567 /*
568 * The block cipher is only invoked once per message, so for long
569 * messages (e.g. sectors for disk encryption) its performance doesn't
570 * matter as much as that of the stream cipher and hash function. Thus,
571 * weigh the block cipher's ->cra_priority less.
572 */
573 inst->alg.base.cra_priority = (4 * streamcipher_alg->base.cra_priority +
574 2 * hash_alg->base.cra_priority +
575 blockcipher_alg->cra_priority) / 7;
576
577 inst->alg.setkey = adiantum_setkey;
578 inst->alg.encrypt = adiantum_encrypt;
579 inst->alg.decrypt = adiantum_decrypt;
580 inst->alg.init = adiantum_init_tfm;
581 inst->alg.exit = adiantum_exit_tfm;
582 inst->alg.min_keysize = crypto_skcipher_alg_min_keysize(streamcipher_alg);
583 inst->alg.max_keysize = crypto_skcipher_alg_max_keysize(streamcipher_alg);
584 inst->alg.ivsize = TWEAK_SIZE;
585
586 inst->free = adiantum_free_instance;
587
588 err = skcipher_register_instance(tmpl, inst);
589 if (err) {
590 err_free_inst:
591 adiantum_free_instance(inst);
592 }
593 return err;
594 }
595
596 /* adiantum(streamcipher_name, blockcipher_name [, nhpoly1305_name]) */
597 static struct crypto_template adiantum_tmpl = {
598 .name = "adiantum",
599 .create = adiantum_create,
600 .module = THIS_MODULE,
601 };
602
adiantum_module_init(void)603 static int __init adiantum_module_init(void)
604 {
605 return crypto_register_template(&adiantum_tmpl);
606 }
607
adiantum_module_exit(void)608 static void __exit adiantum_module_exit(void)
609 {
610 crypto_unregister_template(&adiantum_tmpl);
611 }
612
613 subsys_initcall(adiantum_module_init);
614 module_exit(adiantum_module_exit);
615
616 MODULE_DESCRIPTION("Adiantum length-preserving encryption mode");
617 MODULE_LICENSE("GPL v2");
618 MODULE_AUTHOR("Eric Biggers <ebiggers@google.com>");
619 MODULE_ALIAS_CRYPTO("adiantum");
620 MODULE_IMPORT_NS(CRYPTO_INTERNAL);
621
