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/hash.h>
36 #include <crypto/internal/skcipher.h>
37 #include <crypto/nhpoly1305.h>
38 #include <crypto/scatterwalk.h>
39 #include <linux/module.h>
40
41 #include "internal.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_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_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 crypto_skcipher_set_flags(tfm,
138 crypto_skcipher_get_flags(tctx->streamcipher) &
139 CRYPTO_TFM_RES_MASK);
140 if (err)
141 return err;
142
143 /* Derive the subkeys */
144 data = kzalloc(sizeof(*data) +
145 crypto_skcipher_reqsize(tctx->streamcipher), GFP_KERNEL);
146 if (!data)
147 return -ENOMEM;
148 data->iv[0] = 1;
149 sg_init_one(&data->sg, data->derived_keys, sizeof(data->derived_keys));
150 crypto_init_wait(&data->wait);
151 skcipher_request_set_tfm(&data->req, tctx->streamcipher);
152 skcipher_request_set_callback(&data->req, CRYPTO_TFM_REQ_MAY_SLEEP |
153 CRYPTO_TFM_REQ_MAY_BACKLOG,
154 crypto_req_done, &data->wait);
155 skcipher_request_set_crypt(&data->req, &data->sg, &data->sg,
156 sizeof(data->derived_keys), data->iv);
157 err = crypto_wait_req(crypto_skcipher_encrypt(&data->req), &data->wait);
158 if (err)
159 goto out;
160 keyp = data->derived_keys;
161
162 /* Set the block cipher key (K_E) */
163 crypto_cipher_clear_flags(tctx->blockcipher, CRYPTO_TFM_REQ_MASK);
164 crypto_cipher_set_flags(tctx->blockcipher,
165 crypto_skcipher_get_flags(tfm) &
166 CRYPTO_TFM_REQ_MASK);
167 err = crypto_cipher_setkey(tctx->blockcipher, keyp,
168 BLOCKCIPHER_KEY_SIZE);
169 crypto_skcipher_set_flags(tfm,
170 crypto_cipher_get_flags(tctx->blockcipher) &
171 CRYPTO_TFM_RES_MASK);
172 if (err)
173 goto out;
174 keyp += BLOCKCIPHER_KEY_SIZE;
175
176 /* Set the hash key (K_H) */
177 poly1305_core_setkey(&tctx->header_hash_key, keyp);
178 keyp += POLY1305_BLOCK_SIZE;
179
180 crypto_shash_clear_flags(tctx->hash, CRYPTO_TFM_REQ_MASK);
181 crypto_shash_set_flags(tctx->hash, crypto_skcipher_get_flags(tfm) &
182 CRYPTO_TFM_REQ_MASK);
183 err = crypto_shash_setkey(tctx->hash, keyp, NHPOLY1305_KEY_SIZE);
184 crypto_skcipher_set_flags(tfm, crypto_shash_get_flags(tctx->hash) &
185 CRYPTO_TFM_RES_MASK);
186 keyp += NHPOLY1305_KEY_SIZE;
187 WARN_ON(keyp != &data->derived_keys[ARRAY_SIZE(data->derived_keys)]);
188 out:
189 kzfree(data);
190 return err;
191 }
192
193 /* Addition in Z/(2^{128}Z) */
le128_add(le128 * r,const le128 * v1,const le128 * v2)194 static inline void le128_add(le128 *r, const le128 *v1, const le128 *v2)
195 {
196 u64 x = le64_to_cpu(v1->b);
197 u64 y = le64_to_cpu(v2->b);
198
199 r->b = cpu_to_le64(x + y);
200 r->a = cpu_to_le64(le64_to_cpu(v1->a) + le64_to_cpu(v2->a) +
201 (x + y < x));
202 }
203
204 /* Subtraction in Z/(2^{128}Z) */
le128_sub(le128 * r,const le128 * v1,const le128 * v2)205 static inline void le128_sub(le128 *r, const le128 *v1, const le128 *v2)
206 {
207 u64 x = le64_to_cpu(v1->b);
208 u64 y = le64_to_cpu(v2->b);
209
210 r->b = cpu_to_le64(x - y);
211 r->a = cpu_to_le64(le64_to_cpu(v1->a) - le64_to_cpu(v2->a) -
212 (x - y > x));
213 }
214
215 /*
216 * Apply the Poly1305 ε-∆U hash function to (bulk length, tweak) and save the
217 * result to rctx->header_hash. This is the calculation
218 *
219 * H_T ← Poly1305_{K_T}(bin_{128}(|L|) || T)
220 *
221 * from the procedure in section 6.4 of the Adiantum paper. The resulting value
222 * is reused in both the first and second hash steps. Specifically, it's added
223 * to the result of an independently keyed ε-∆U hash function (for equal length
224 * inputs only) taken over the left-hand part (the "bulk") of the message, to
225 * give the overall Adiantum hash of the (tweak, left-hand part) pair.
226 */
adiantum_hash_header(struct skcipher_request * req)227 static void adiantum_hash_header(struct skcipher_request *req)
228 {
229 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
230 const struct adiantum_tfm_ctx *tctx = crypto_skcipher_ctx(tfm);
231 struct adiantum_request_ctx *rctx = skcipher_request_ctx(req);
232 const unsigned int bulk_len = req->cryptlen - BLOCKCIPHER_BLOCK_SIZE;
233 struct {
234 __le64 message_bits;
235 __le64 padding;
236 } header = {
237 .message_bits = cpu_to_le64((u64)bulk_len * 8)
238 };
239 struct poly1305_state state;
240
241 poly1305_core_init(&state);
242
243 BUILD_BUG_ON(sizeof(header) % POLY1305_BLOCK_SIZE != 0);
244 poly1305_core_blocks(&state, &tctx->header_hash_key,
245 &header, sizeof(header) / POLY1305_BLOCK_SIZE);
246
247 BUILD_BUG_ON(TWEAK_SIZE % POLY1305_BLOCK_SIZE != 0);
248 poly1305_core_blocks(&state, &tctx->header_hash_key, req->iv,
249 TWEAK_SIZE / POLY1305_BLOCK_SIZE);
250
251 poly1305_core_emit(&state, &rctx->header_hash);
252 }
253
254 /* Hash the left-hand part (the "bulk") of the message using NHPoly1305 */
adiantum_hash_message(struct skcipher_request * req,struct scatterlist * sgl,le128 * digest)255 static int adiantum_hash_message(struct skcipher_request *req,
256 struct scatterlist *sgl, le128 *digest)
257 {
258 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
259 const struct adiantum_tfm_ctx *tctx = crypto_skcipher_ctx(tfm);
260 struct adiantum_request_ctx *rctx = skcipher_request_ctx(req);
261 const unsigned int bulk_len = req->cryptlen - BLOCKCIPHER_BLOCK_SIZE;
262 struct shash_desc *hash_desc = &rctx->u.hash_desc;
263 struct sg_mapping_iter miter;
264 unsigned int i, n;
265 int err;
266
267 hash_desc->tfm = tctx->hash;
268
269 err = crypto_shash_init(hash_desc);
270 if (err)
271 return err;
272
273 sg_miter_start(&miter, sgl, sg_nents(sgl),
274 SG_MITER_FROM_SG | SG_MITER_ATOMIC);
275 for (i = 0; i < bulk_len; i += n) {
276 sg_miter_next(&miter);
277 n = min_t(unsigned int, miter.length, bulk_len - i);
278 err = crypto_shash_update(hash_desc, miter.addr, n);
279 if (err)
280 break;
281 }
282 sg_miter_stop(&miter);
283 if (err)
284 return err;
285
286 return crypto_shash_final(hash_desc, (u8 *)digest);
287 }
288
289 /* Continue Adiantum encryption/decryption after the stream cipher step */
adiantum_finish(struct skcipher_request * req)290 static int adiantum_finish(struct skcipher_request *req)
291 {
292 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
293 const struct adiantum_tfm_ctx *tctx = crypto_skcipher_ctx(tfm);
294 struct adiantum_request_ctx *rctx = skcipher_request_ctx(req);
295 const unsigned int bulk_len = req->cryptlen - BLOCKCIPHER_BLOCK_SIZE;
296 le128 digest;
297 int err;
298
299 /* If decrypting, decrypt C_M with the block cipher to get P_M */
300 if (!rctx->enc)
301 crypto_cipher_decrypt_one(tctx->blockcipher, rctx->rbuf.bytes,
302 rctx->rbuf.bytes);
303
304 /*
305 * Second hash step
306 * enc: C_R = C_M - H_{K_H}(T, C_L)
307 * dec: P_R = P_M - H_{K_H}(T, P_L)
308 */
309 err = adiantum_hash_message(req, req->dst, &digest);
310 if (err)
311 return err;
312 le128_add(&digest, &digest, &rctx->header_hash);
313 le128_sub(&rctx->rbuf.bignum, &rctx->rbuf.bignum, &digest);
314 scatterwalk_map_and_copy(&rctx->rbuf.bignum, req->dst,
315 bulk_len, BLOCKCIPHER_BLOCK_SIZE, 1);
316 return 0;
317 }
318
adiantum_streamcipher_done(struct crypto_async_request * areq,int err)319 static void adiantum_streamcipher_done(struct crypto_async_request *areq,
320 int err)
321 {
322 struct skcipher_request *req = areq->data;
323
324 if (!err)
325 err = adiantum_finish(req);
326
327 skcipher_request_complete(req, err);
328 }
329
adiantum_crypt(struct skcipher_request * req,bool enc)330 static int adiantum_crypt(struct skcipher_request *req, bool enc)
331 {
332 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
333 const struct adiantum_tfm_ctx *tctx = crypto_skcipher_ctx(tfm);
334 struct adiantum_request_ctx *rctx = skcipher_request_ctx(req);
335 const unsigned int bulk_len = req->cryptlen - BLOCKCIPHER_BLOCK_SIZE;
336 unsigned int stream_len;
337 le128 digest;
338 int err;
339
340 if (req->cryptlen < BLOCKCIPHER_BLOCK_SIZE)
341 return -EINVAL;
342
343 rctx->enc = enc;
344
345 /*
346 * First hash step
347 * enc: P_M = P_R + H_{K_H}(T, P_L)
348 * dec: C_M = C_R + H_{K_H}(T, C_L)
349 */
350 adiantum_hash_header(req);
351 err = adiantum_hash_message(req, req->src, &digest);
352 if (err)
353 return err;
354 le128_add(&digest, &digest, &rctx->header_hash);
355 scatterwalk_map_and_copy(&rctx->rbuf.bignum, req->src,
356 bulk_len, BLOCKCIPHER_BLOCK_SIZE, 0);
357 le128_add(&rctx->rbuf.bignum, &rctx->rbuf.bignum, &digest);
358
359 /* If encrypting, encrypt P_M with the block cipher to get C_M */
360 if (enc)
361 crypto_cipher_encrypt_one(tctx->blockcipher, rctx->rbuf.bytes,
362 rctx->rbuf.bytes);
363
364 /* Initialize the rest of the XChaCha IV (first part is C_M) */
365 BUILD_BUG_ON(BLOCKCIPHER_BLOCK_SIZE != 16);
366 BUILD_BUG_ON(XCHACHA_IV_SIZE != 32); /* nonce || stream position */
367 rctx->rbuf.words[4] = cpu_to_le32(1);
368 rctx->rbuf.words[5] = 0;
369 rctx->rbuf.words[6] = 0;
370 rctx->rbuf.words[7] = 0;
371
372 /*
373 * XChaCha needs to be done on all the data except the last 16 bytes;
374 * for disk encryption that usually means 4080 or 496 bytes. But ChaCha
375 * implementations tend to be most efficient when passed a whole number
376 * of 64-byte ChaCha blocks, or sometimes even a multiple of 256 bytes.
377 * And here it doesn't matter whether the last 16 bytes are written to,
378 * as the second hash step will overwrite them. Thus, round the XChaCha
379 * length up to the next 64-byte boundary if possible.
380 */
381 stream_len = bulk_len;
382 if (round_up(stream_len, CHACHA_BLOCK_SIZE) <= req->cryptlen)
383 stream_len = round_up(stream_len, CHACHA_BLOCK_SIZE);
384
385 skcipher_request_set_tfm(&rctx->u.streamcipher_req, tctx->streamcipher);
386 skcipher_request_set_crypt(&rctx->u.streamcipher_req, req->src,
387 req->dst, stream_len, &rctx->rbuf);
388 skcipher_request_set_callback(&rctx->u.streamcipher_req,
389 req->base.flags,
390 adiantum_streamcipher_done, req);
391 return crypto_skcipher_encrypt(&rctx->u.streamcipher_req) ?:
392 adiantum_finish(req);
393 }
394
adiantum_encrypt(struct skcipher_request * req)395 static int adiantum_encrypt(struct skcipher_request *req)
396 {
397 return adiantum_crypt(req, true);
398 }
399
adiantum_decrypt(struct skcipher_request * req)400 static int adiantum_decrypt(struct skcipher_request *req)
401 {
402 return adiantum_crypt(req, false);
403 }
404
adiantum_init_tfm(struct crypto_skcipher * tfm)405 static int adiantum_init_tfm(struct crypto_skcipher *tfm)
406 {
407 struct skcipher_instance *inst = skcipher_alg_instance(tfm);
408 struct adiantum_instance_ctx *ictx = skcipher_instance_ctx(inst);
409 struct adiantum_tfm_ctx *tctx = crypto_skcipher_ctx(tfm);
410 struct crypto_skcipher *streamcipher;
411 struct crypto_cipher *blockcipher;
412 struct crypto_shash *hash;
413 unsigned int subreq_size;
414 int err;
415
416 streamcipher = crypto_spawn_skcipher(&ictx->streamcipher_spawn);
417 if (IS_ERR(streamcipher))
418 return PTR_ERR(streamcipher);
419
420 blockcipher = crypto_spawn_cipher(&ictx->blockcipher_spawn);
421 if (IS_ERR(blockcipher)) {
422 err = PTR_ERR(blockcipher);
423 goto err_free_streamcipher;
424 }
425
426 hash = crypto_spawn_shash(&ictx->hash_spawn);
427 if (IS_ERR(hash)) {
428 err = PTR_ERR(hash);
429 goto err_free_blockcipher;
430 }
431
432 tctx->streamcipher = streamcipher;
433 tctx->blockcipher = blockcipher;
434 tctx->hash = hash;
435
436 BUILD_BUG_ON(offsetofend(struct adiantum_request_ctx, u) !=
437 sizeof(struct adiantum_request_ctx));
438 subreq_size = max(FIELD_SIZEOF(struct adiantum_request_ctx,
439 u.hash_desc) +
440 crypto_shash_descsize(hash),
441 FIELD_SIZEOF(struct adiantum_request_ctx,
442 u.streamcipher_req) +
443 crypto_skcipher_reqsize(streamcipher));
444
445 crypto_skcipher_set_reqsize(tfm,
446 offsetof(struct adiantum_request_ctx, u) +
447 subreq_size);
448 return 0;
449
450 err_free_blockcipher:
451 crypto_free_cipher(blockcipher);
452 err_free_streamcipher:
453 crypto_free_skcipher(streamcipher);
454 return err;
455 }
456
adiantum_exit_tfm(struct crypto_skcipher * tfm)457 static void adiantum_exit_tfm(struct crypto_skcipher *tfm)
458 {
459 struct adiantum_tfm_ctx *tctx = crypto_skcipher_ctx(tfm);
460
461 crypto_free_skcipher(tctx->streamcipher);
462 crypto_free_cipher(tctx->blockcipher);
463 crypto_free_shash(tctx->hash);
464 }
465
adiantum_free_instance(struct skcipher_instance * inst)466 static void adiantum_free_instance(struct skcipher_instance *inst)
467 {
468 struct adiantum_instance_ctx *ictx = skcipher_instance_ctx(inst);
469
470 crypto_drop_skcipher(&ictx->streamcipher_spawn);
471 crypto_drop_spawn(&ictx->blockcipher_spawn);
472 crypto_drop_shash(&ictx->hash_spawn);
473 kfree(inst);
474 }
475
476 /*
477 * Check for a supported set of inner algorithms.
478 * See the comment at the beginning of this file.
479 */
adiantum_supported_algorithms(struct skcipher_alg * streamcipher_alg,struct crypto_alg * blockcipher_alg,struct shash_alg * hash_alg)480 static bool adiantum_supported_algorithms(struct skcipher_alg *streamcipher_alg,
481 struct crypto_alg *blockcipher_alg,
482 struct shash_alg *hash_alg)
483 {
484 if (strcmp(streamcipher_alg->base.cra_name, "xchacha12") != 0 &&
485 strcmp(streamcipher_alg->base.cra_name, "xchacha20") != 0)
486 return false;
487
488 if (blockcipher_alg->cra_cipher.cia_min_keysize > BLOCKCIPHER_KEY_SIZE ||
489 blockcipher_alg->cra_cipher.cia_max_keysize < BLOCKCIPHER_KEY_SIZE)
490 return false;
491 if (blockcipher_alg->cra_blocksize != BLOCKCIPHER_BLOCK_SIZE)
492 return false;
493
494 if (strcmp(hash_alg->base.cra_name, "nhpoly1305") != 0)
495 return false;
496
497 return true;
498 }
499
adiantum_create(struct crypto_template * tmpl,struct rtattr ** tb)500 static int adiantum_create(struct crypto_template *tmpl, struct rtattr **tb)
501 {
502 struct crypto_attr_type *algt;
503 const char *streamcipher_name;
504 const char *blockcipher_name;
505 const char *nhpoly1305_name;
506 struct skcipher_instance *inst;
507 struct adiantum_instance_ctx *ictx;
508 struct skcipher_alg *streamcipher_alg;
509 struct crypto_alg *blockcipher_alg;
510 struct crypto_alg *_hash_alg;
511 struct shash_alg *hash_alg;
512 int err;
513
514 algt = crypto_get_attr_type(tb);
515 if (IS_ERR(algt))
516 return PTR_ERR(algt);
517
518 if ((algt->type ^ CRYPTO_ALG_TYPE_SKCIPHER) & algt->mask)
519 return -EINVAL;
520
521 streamcipher_name = crypto_attr_alg_name(tb[1]);
522 if (IS_ERR(streamcipher_name))
523 return PTR_ERR(streamcipher_name);
524
525 blockcipher_name = crypto_attr_alg_name(tb[2]);
526 if (IS_ERR(blockcipher_name))
527 return PTR_ERR(blockcipher_name);
528
529 nhpoly1305_name = crypto_attr_alg_name(tb[3]);
530 if (nhpoly1305_name == ERR_PTR(-ENOENT))
531 nhpoly1305_name = "nhpoly1305";
532 if (IS_ERR(nhpoly1305_name))
533 return PTR_ERR(nhpoly1305_name);
534
535 inst = kzalloc(sizeof(*inst) + sizeof(*ictx), GFP_KERNEL);
536 if (!inst)
537 return -ENOMEM;
538 ictx = skcipher_instance_ctx(inst);
539
540 /* Stream cipher, e.g. "xchacha12" */
541 crypto_set_skcipher_spawn(&ictx->streamcipher_spawn,
542 skcipher_crypto_instance(inst));
543 err = crypto_grab_skcipher(&ictx->streamcipher_spawn, streamcipher_name,
544 0, crypto_requires_sync(algt->type,
545 algt->mask));
546 if (err)
547 goto out_free_inst;
548 streamcipher_alg = crypto_spawn_skcipher_alg(&ictx->streamcipher_spawn);
549
550 /* Block cipher, e.g. "aes" */
551 crypto_set_spawn(&ictx->blockcipher_spawn,
552 skcipher_crypto_instance(inst));
553 err = crypto_grab_spawn(&ictx->blockcipher_spawn, blockcipher_name,
554 CRYPTO_ALG_TYPE_CIPHER, CRYPTO_ALG_TYPE_MASK);
555 if (err)
556 goto out_drop_streamcipher;
557 blockcipher_alg = ictx->blockcipher_spawn.alg;
558
559 /* NHPoly1305 ε-∆U hash function */
560 _hash_alg = crypto_alg_mod_lookup(nhpoly1305_name,
561 CRYPTO_ALG_TYPE_SHASH,
562 CRYPTO_ALG_TYPE_MASK);
563 if (IS_ERR(_hash_alg)) {
564 err = PTR_ERR(_hash_alg);
565 goto out_drop_blockcipher;
566 }
567 hash_alg = __crypto_shash_alg(_hash_alg);
568 err = crypto_init_shash_spawn(&ictx->hash_spawn, hash_alg,
569 skcipher_crypto_instance(inst));
570 if (err)
571 goto out_put_hash;
572
573 /* Check the set of algorithms */
574 if (!adiantum_supported_algorithms(streamcipher_alg, blockcipher_alg,
575 hash_alg)) {
576 pr_warn("Unsupported Adiantum instantiation: (%s,%s,%s)\n",
577 streamcipher_alg->base.cra_name,
578 blockcipher_alg->cra_name, hash_alg->base.cra_name);
579 err = -EINVAL;
580 goto out_drop_hash;
581 }
582
583 /* Instance fields */
584
585 err = -ENAMETOOLONG;
586 if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
587 "adiantum(%s,%s)", streamcipher_alg->base.cra_name,
588 blockcipher_alg->cra_name) >= CRYPTO_MAX_ALG_NAME)
589 goto out_drop_hash;
590 if (snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME,
591 "adiantum(%s,%s,%s)",
592 streamcipher_alg->base.cra_driver_name,
593 blockcipher_alg->cra_driver_name,
594 hash_alg->base.cra_driver_name) >= CRYPTO_MAX_ALG_NAME)
595 goto out_drop_hash;
596
597 inst->alg.base.cra_flags = streamcipher_alg->base.cra_flags &
598 CRYPTO_ALG_ASYNC;
599 inst->alg.base.cra_blocksize = BLOCKCIPHER_BLOCK_SIZE;
600 inst->alg.base.cra_ctxsize = sizeof(struct adiantum_tfm_ctx);
601 inst->alg.base.cra_alignmask = streamcipher_alg->base.cra_alignmask |
602 hash_alg->base.cra_alignmask;
603 /*
604 * The block cipher is only invoked once per message, so for long
605 * messages (e.g. sectors for disk encryption) its performance doesn't
606 * matter as much as that of the stream cipher and hash function. Thus,
607 * weigh the block cipher's ->cra_priority less.
608 */
609 inst->alg.base.cra_priority = (4 * streamcipher_alg->base.cra_priority +
610 2 * hash_alg->base.cra_priority +
611 blockcipher_alg->cra_priority) / 7;
612
613 inst->alg.setkey = adiantum_setkey;
614 inst->alg.encrypt = adiantum_encrypt;
615 inst->alg.decrypt = adiantum_decrypt;
616 inst->alg.init = adiantum_init_tfm;
617 inst->alg.exit = adiantum_exit_tfm;
618 inst->alg.min_keysize = crypto_skcipher_alg_min_keysize(streamcipher_alg);
619 inst->alg.max_keysize = crypto_skcipher_alg_max_keysize(streamcipher_alg);
620 inst->alg.ivsize = TWEAK_SIZE;
621
622 inst->free = adiantum_free_instance;
623
624 err = skcipher_register_instance(tmpl, inst);
625 if (err)
626 goto out_drop_hash;
627
628 crypto_mod_put(_hash_alg);
629 return 0;
630
631 out_drop_hash:
632 crypto_drop_shash(&ictx->hash_spawn);
633 out_put_hash:
634 crypto_mod_put(_hash_alg);
635 out_drop_blockcipher:
636 crypto_drop_spawn(&ictx->blockcipher_spawn);
637 out_drop_streamcipher:
638 crypto_drop_skcipher(&ictx->streamcipher_spawn);
639 out_free_inst:
640 kfree(inst);
641 return err;
642 }
643
644 /* adiantum(streamcipher_name, blockcipher_name [, nhpoly1305_name]) */
645 static struct crypto_template adiantum_tmpl = {
646 .name = "adiantum",
647 .create = adiantum_create,
648 .module = THIS_MODULE,
649 };
650
adiantum_module_init(void)651 static int __init adiantum_module_init(void)
652 {
653 return crypto_register_template(&adiantum_tmpl);
654 }
655
adiantum_module_exit(void)656 static void __exit adiantum_module_exit(void)
657 {
658 crypto_unregister_template(&adiantum_tmpl);
659 }
660
661 subsys_initcall(adiantum_module_init);
662 module_exit(adiantum_module_exit);
663
664 MODULE_DESCRIPTION("Adiantum length-preserving encryption mode");
665 MODULE_LICENSE("GPL v2");
666 MODULE_AUTHOR("Eric Biggers <ebiggers@google.com>");
667 MODULE_ALIAS_CRYPTO("adiantum");
668
