Commit | Line | Data |
---|---|---|
2874c5fd | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
f19f5111 RS |
2 | /* XTS: as defined in IEEE1619/D16 |
3 | * http://grouper.ieee.org/groups/1619/email/pdf00086.pdf | |
f19f5111 RS |
4 | * |
5 | * Copyright (c) 2007 Rik Snel <rsnel@cube.dyndns.org> | |
6 | * | |
ddbc7361 | 7 | * Based on ecb.c |
f19f5111 | 8 | * Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au> |
f19f5111 | 9 | */ |
f1c131b4 HX |
10 | #include <crypto/internal/skcipher.h> |
11 | #include <crypto/scatterwalk.h> | |
f19f5111 RS |
12 | #include <linux/err.h> |
13 | #include <linux/init.h> | |
14 | #include <linux/kernel.h> | |
15 | #include <linux/module.h> | |
16 | #include <linux/scatterlist.h> | |
17 | #include <linux/slab.h> | |
18 | ||
ce004556 | 19 | #include <crypto/xts.h> |
f19f5111 RS |
20 | #include <crypto/b128ops.h> |
21 | #include <crypto/gf128mul.h> | |
22 | ||
23 | struct priv { | |
f1c131b4 | 24 | struct crypto_skcipher *child; |
f19f5111 RS |
25 | struct crypto_cipher *tweak; |
26 | }; | |
27 | ||
f1c131b4 HX |
28 | struct xts_instance_ctx { |
29 | struct crypto_skcipher_spawn spawn; | |
30 | char name[CRYPTO_MAX_ALG_NAME]; | |
31 | }; | |
32 | ||
33 | struct rctx { | |
e55318c8 | 34 | le128 t; |
8083b1bf AB |
35 | struct scatterlist *tail; |
36 | struct scatterlist sg[2]; | |
f1c131b4 HX |
37 | struct skcipher_request subreq; |
38 | }; | |
39 | ||
40 | static int setkey(struct crypto_skcipher *parent, const u8 *key, | |
f19f5111 RS |
41 | unsigned int keylen) |
42 | { | |
f1c131b4 HX |
43 | struct priv *ctx = crypto_skcipher_ctx(parent); |
44 | struct crypto_skcipher *child; | |
45 | struct crypto_cipher *tweak; | |
f19f5111 RS |
46 | int err; |
47 | ||
f1c131b4 | 48 | err = xts_verify_key(parent, key, keylen); |
28856a9e SM |
49 | if (err) |
50 | return err; | |
f19f5111 | 51 | |
f1c131b4 HX |
52 | keylen /= 2; |
53 | ||
25985edc | 54 | /* we need two cipher instances: one to compute the initial 'tweak' |
f19f5111 RS |
55 | * by encrypting the IV (usually the 'plain' iv) and the other |
56 | * one to encrypt and decrypt the data */ | |
57 | ||
58 | /* tweak cipher, uses Key2 i.e. the second half of *key */ | |
f1c131b4 HX |
59 | tweak = ctx->tweak; |
60 | crypto_cipher_clear_flags(tweak, CRYPTO_TFM_REQ_MASK); | |
61 | crypto_cipher_set_flags(tweak, crypto_skcipher_get_flags(parent) & | |
f19f5111 | 62 | CRYPTO_TFM_REQ_MASK); |
f1c131b4 HX |
63 | err = crypto_cipher_setkey(tweak, key + keylen, keylen); |
64 | crypto_skcipher_set_flags(parent, crypto_cipher_get_flags(tweak) & | |
65 | CRYPTO_TFM_RES_MASK); | |
f19f5111 RS |
66 | if (err) |
67 | return err; | |
68 | ||
f1c131b4 | 69 | /* data cipher, uses Key1 i.e. the first half of *key */ |
f19f5111 | 70 | child = ctx->child; |
f1c131b4 HX |
71 | crypto_skcipher_clear_flags(child, CRYPTO_TFM_REQ_MASK); |
72 | crypto_skcipher_set_flags(child, crypto_skcipher_get_flags(parent) & | |
73 | CRYPTO_TFM_REQ_MASK); | |
74 | err = crypto_skcipher_setkey(child, key, keylen); | |
75 | crypto_skcipher_set_flags(parent, crypto_skcipher_get_flags(child) & | |
76 | CRYPTO_TFM_RES_MASK); | |
f19f5111 | 77 | |
f1c131b4 HX |
78 | return err; |
79 | } | |
f19f5111 | 80 | |
78105c7e OM |
81 | /* |
82 | * We compute the tweak masks twice (both before and after the ECB encryption or | |
83 | * decryption) to avoid having to allocate a temporary buffer and/or make | |
84 | * mutliple calls to the 'ecb(..)' instance, which usually would be slower than | |
85 | * just doing the gf128mul_x_ble() calls again. | |
86 | */ | |
8083b1bf | 87 | static int xor_tweak(struct skcipher_request *req, bool second_pass, bool enc) |
f1c131b4 HX |
88 | { |
89 | struct rctx *rctx = skcipher_request_ctx(req); | |
78105c7e | 90 | struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); |
8083b1bf | 91 | const bool cts = (req->cryptlen % XTS_BLOCK_SIZE); |
f1c131b4 HX |
92 | const int bs = XTS_BLOCK_SIZE; |
93 | struct skcipher_walk w; | |
78105c7e | 94 | le128 t = rctx->t; |
f1c131b4 | 95 | int err; |
f19f5111 | 96 | |
78105c7e OM |
97 | if (second_pass) { |
98 | req = &rctx->subreq; | |
99 | /* set to our TFM to enforce correct alignment: */ | |
100 | skcipher_request_set_tfm(req, tfm); | |
f1c131b4 | 101 | } |
78105c7e | 102 | err = skcipher_walk_virt(&w, req, false); |
f19f5111 | 103 | |
f1c131b4 HX |
104 | while (w.nbytes) { |
105 | unsigned int avail = w.nbytes; | |
e55318c8 OM |
106 | le128 *wsrc; |
107 | le128 *wdst; | |
f19f5111 | 108 | |
f1c131b4 HX |
109 | wsrc = w.src.virt.addr; |
110 | wdst = w.dst.virt.addr; | |
f19f5111 | 111 | |
f1c131b4 | 112 | do { |
8083b1bf AB |
113 | if (unlikely(cts) && |
114 | w.total - w.nbytes + avail < 2 * XTS_BLOCK_SIZE) { | |
115 | if (!enc) { | |
116 | if (second_pass) | |
117 | rctx->t = t; | |
118 | gf128mul_x_ble(&t, &t); | |
119 | } | |
120 | le128_xor(wdst, &t, wsrc); | |
121 | if (enc && second_pass) | |
122 | gf128mul_x_ble(&rctx->t, &t); | |
123 | skcipher_walk_done(&w, avail - bs); | |
124 | return 0; | |
125 | } | |
126 | ||
78105c7e OM |
127 | le128_xor(wdst++, &t, wsrc++); |
128 | gf128mul_x_ble(&t, &t); | |
f19f5111 RS |
129 | } while ((avail -= bs) >= bs); |
130 | ||
f1c131b4 HX |
131 | err = skcipher_walk_done(&w, avail); |
132 | } | |
133 | ||
f19f5111 RS |
134 | return err; |
135 | } | |
136 | ||
8083b1bf AB |
137 | static int xor_tweak_pre(struct skcipher_request *req, bool enc) |
138 | { | |
139 | return xor_tweak(req, false, enc); | |
140 | } | |
141 | ||
142 | static int xor_tweak_post(struct skcipher_request *req, bool enc) | |
143 | { | |
144 | return xor_tweak(req, true, enc); | |
145 | } | |
146 | ||
147 | static void cts_done(struct crypto_async_request *areq, int err) | |
f19f5111 | 148 | { |
8083b1bf AB |
149 | struct skcipher_request *req = areq->data; |
150 | le128 b; | |
151 | ||
152 | if (!err) { | |
153 | struct rctx *rctx = skcipher_request_ctx(req); | |
154 | ||
155 | scatterwalk_map_and_copy(&b, rctx->tail, 0, XTS_BLOCK_SIZE, 0); | |
156 | le128_xor(&b, &rctx->t, &b); | |
157 | scatterwalk_map_and_copy(&b, rctx->tail, 0, XTS_BLOCK_SIZE, 1); | |
158 | } | |
159 | ||
160 | skcipher_request_complete(req, err); | |
161 | } | |
162 | ||
163 | static int cts_final(struct skcipher_request *req, | |
164 | int (*crypt)(struct skcipher_request *req)) | |
165 | { | |
166 | struct priv *ctx = crypto_skcipher_ctx(crypto_skcipher_reqtfm(req)); | |
167 | int offset = req->cryptlen & ~(XTS_BLOCK_SIZE - 1); | |
168 | struct rctx *rctx = skcipher_request_ctx(req); | |
169 | struct skcipher_request *subreq = &rctx->subreq; | |
170 | int tail = req->cryptlen % XTS_BLOCK_SIZE; | |
171 | le128 b[2]; | |
172 | int err; | |
173 | ||
174 | rctx->tail = scatterwalk_ffwd(rctx->sg, req->dst, | |
175 | offset - XTS_BLOCK_SIZE); | |
176 | ||
177 | scatterwalk_map_and_copy(b, rctx->tail, 0, XTS_BLOCK_SIZE, 0); | |
178 | memcpy(b + 1, b, tail); | |
179 | scatterwalk_map_and_copy(b, req->src, offset, tail, 0); | |
180 | ||
181 | le128_xor(b, &rctx->t, b); | |
182 | ||
183 | scatterwalk_map_and_copy(b, rctx->tail, 0, XTS_BLOCK_SIZE + tail, 1); | |
184 | ||
185 | skcipher_request_set_tfm(subreq, ctx->child); | |
186 | skcipher_request_set_callback(subreq, req->base.flags, cts_done, req); | |
187 | skcipher_request_set_crypt(subreq, rctx->tail, rctx->tail, | |
188 | XTS_BLOCK_SIZE, NULL); | |
189 | ||
190 | err = crypt(subreq); | |
191 | if (err) | |
192 | return err; | |
193 | ||
194 | scatterwalk_map_and_copy(b, rctx->tail, 0, XTS_BLOCK_SIZE, 0); | |
195 | le128_xor(b, &rctx->t, b); | |
196 | scatterwalk_map_and_copy(b, rctx->tail, 0, XTS_BLOCK_SIZE, 1); | |
197 | ||
198 | return 0; | |
f1c131b4 HX |
199 | } |
200 | ||
8083b1bf | 201 | static void encrypt_done(struct crypto_async_request *areq, int err) |
f1c131b4 | 202 | { |
8083b1bf AB |
203 | struct skcipher_request *req = areq->data; |
204 | ||
205 | if (!err) { | |
206 | struct rctx *rctx = skcipher_request_ctx(req); | |
207 | ||
208 | rctx->subreq.base.flags &= ~CRYPTO_TFM_REQ_MAY_SLEEP; | |
209 | err = xor_tweak_post(req, true); | |
210 | ||
211 | if (!err && unlikely(req->cryptlen % XTS_BLOCK_SIZE)) { | |
212 | err = cts_final(req, crypto_skcipher_encrypt); | |
213 | if (err == -EINPROGRESS) | |
214 | return; | |
215 | } | |
216 | } | |
217 | ||
218 | skcipher_request_complete(req, err); | |
f1c131b4 HX |
219 | } |
220 | ||
8083b1bf | 221 | static void decrypt_done(struct crypto_async_request *areq, int err) |
f1c131b4 HX |
222 | { |
223 | struct skcipher_request *req = areq->data; | |
aa4a829b | 224 | |
44427c0f HX |
225 | if (!err) { |
226 | struct rctx *rctx = skcipher_request_ctx(req); | |
227 | ||
228 | rctx->subreq.base.flags &= ~CRYPTO_TFM_REQ_MAY_SLEEP; | |
8083b1bf AB |
229 | err = xor_tweak_post(req, false); |
230 | ||
231 | if (!err && unlikely(req->cryptlen % XTS_BLOCK_SIZE)) { | |
232 | err = cts_final(req, crypto_skcipher_decrypt); | |
233 | if (err == -EINPROGRESS) | |
234 | return; | |
235 | } | |
44427c0f | 236 | } |
f1c131b4 | 237 | |
f1c131b4 HX |
238 | skcipher_request_complete(req, err); |
239 | } | |
240 | ||
8083b1bf | 241 | static int init_crypt(struct skcipher_request *req, crypto_completion_t compl) |
f1c131b4 | 242 | { |
78105c7e | 243 | struct priv *ctx = crypto_skcipher_ctx(crypto_skcipher_reqtfm(req)); |
f1c131b4 | 244 | struct rctx *rctx = skcipher_request_ctx(req); |
78105c7e | 245 | struct skcipher_request *subreq = &rctx->subreq; |
f1c131b4 | 246 | |
8083b1bf AB |
247 | if (req->cryptlen < XTS_BLOCK_SIZE) |
248 | return -EINVAL; | |
249 | ||
78105c7e | 250 | skcipher_request_set_tfm(subreq, ctx->child); |
8083b1bf | 251 | skcipher_request_set_callback(subreq, req->base.flags, compl, req); |
78105c7e | 252 | skcipher_request_set_crypt(subreq, req->dst, req->dst, |
8083b1bf | 253 | req->cryptlen & ~(XTS_BLOCK_SIZE - 1), NULL); |
f1c131b4 | 254 | |
78105c7e OM |
255 | /* calculate first value of T */ |
256 | crypto_cipher_encrypt_one(ctx->tweak, (u8 *)&rctx->t, req->iv); | |
8083b1bf AB |
257 | |
258 | return 0; | |
f1c131b4 HX |
259 | } |
260 | ||
78105c7e | 261 | static int encrypt(struct skcipher_request *req) |
f1c131b4 | 262 | { |
78105c7e OM |
263 | struct rctx *rctx = skcipher_request_ctx(req); |
264 | struct skcipher_request *subreq = &rctx->subreq; | |
8083b1bf AB |
265 | int err; |
266 | ||
267 | err = init_crypt(req, encrypt_done) ?: | |
268 | xor_tweak_pre(req, true) ?: | |
269 | crypto_skcipher_encrypt(subreq) ?: | |
270 | xor_tweak_post(req, true); | |
f1c131b4 | 271 | |
8083b1bf AB |
272 | if (err || likely((req->cryptlen % XTS_BLOCK_SIZE) == 0)) |
273 | return err; | |
274 | ||
275 | return cts_final(req, crypto_skcipher_encrypt); | |
f1c131b4 HX |
276 | } |
277 | ||
278 | static int decrypt(struct skcipher_request *req) | |
279 | { | |
78105c7e OM |
280 | struct rctx *rctx = skcipher_request_ctx(req); |
281 | struct skcipher_request *subreq = &rctx->subreq; | |
8083b1bf AB |
282 | int err; |
283 | ||
284 | err = init_crypt(req, decrypt_done) ?: | |
285 | xor_tweak_pre(req, false) ?: | |
286 | crypto_skcipher_decrypt(subreq) ?: | |
287 | xor_tweak_post(req, false); | |
288 | ||
289 | if (err || likely((req->cryptlen % XTS_BLOCK_SIZE) == 0)) | |
290 | return err; | |
78105c7e | 291 | |
8083b1bf | 292 | return cts_final(req, crypto_skcipher_decrypt); |
f19f5111 RS |
293 | } |
294 | ||
f1c131b4 | 295 | static int init_tfm(struct crypto_skcipher *tfm) |
f19f5111 | 296 | { |
f1c131b4 HX |
297 | struct skcipher_instance *inst = skcipher_alg_instance(tfm); |
298 | struct xts_instance_ctx *ictx = skcipher_instance_ctx(inst); | |
299 | struct priv *ctx = crypto_skcipher_ctx(tfm); | |
300 | struct crypto_skcipher *child; | |
301 | struct crypto_cipher *tweak; | |
f19f5111 | 302 | |
f1c131b4 HX |
303 | child = crypto_spawn_skcipher(&ictx->spawn); |
304 | if (IS_ERR(child)) | |
305 | return PTR_ERR(child); | |
f19f5111 | 306 | |
f1c131b4 | 307 | ctx->child = child; |
f19f5111 | 308 | |
f1c131b4 HX |
309 | tweak = crypto_alloc_cipher(ictx->name, 0, 0); |
310 | if (IS_ERR(tweak)) { | |
311 | crypto_free_skcipher(ctx->child); | |
312 | return PTR_ERR(tweak); | |
f19f5111 RS |
313 | } |
314 | ||
f1c131b4 HX |
315 | ctx->tweak = tweak; |
316 | ||
317 | crypto_skcipher_set_reqsize(tfm, crypto_skcipher_reqsize(child) + | |
318 | sizeof(struct rctx)); | |
f19f5111 RS |
319 | |
320 | return 0; | |
321 | } | |
322 | ||
f1c131b4 | 323 | static void exit_tfm(struct crypto_skcipher *tfm) |
f19f5111 | 324 | { |
f1c131b4 HX |
325 | struct priv *ctx = crypto_skcipher_ctx(tfm); |
326 | ||
327 | crypto_free_skcipher(ctx->child); | |
f19f5111 RS |
328 | crypto_free_cipher(ctx->tweak); |
329 | } | |
330 | ||
f1c131b4 HX |
331 | static void free(struct skcipher_instance *inst) |
332 | { | |
333 | crypto_drop_skcipher(skcipher_instance_ctx(inst)); | |
334 | kfree(inst); | |
335 | } | |
336 | ||
337 | static int create(struct crypto_template *tmpl, struct rtattr **tb) | |
f19f5111 | 338 | { |
f1c131b4 HX |
339 | struct skcipher_instance *inst; |
340 | struct crypto_attr_type *algt; | |
341 | struct xts_instance_ctx *ctx; | |
342 | struct skcipher_alg *alg; | |
343 | const char *cipher_name; | |
89027579 | 344 | u32 mask; |
f19f5111 RS |
345 | int err; |
346 | ||
f1c131b4 HX |
347 | algt = crypto_get_attr_type(tb); |
348 | if (IS_ERR(algt)) | |
349 | return PTR_ERR(algt); | |
350 | ||
351 | if ((algt->type ^ CRYPTO_ALG_TYPE_SKCIPHER) & algt->mask) | |
352 | return -EINVAL; | |
353 | ||
354 | cipher_name = crypto_attr_alg_name(tb[1]); | |
355 | if (IS_ERR(cipher_name)) | |
356 | return PTR_ERR(cipher_name); | |
357 | ||
358 | inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL); | |
359 | if (!inst) | |
360 | return -ENOMEM; | |
361 | ||
362 | ctx = skcipher_instance_ctx(inst); | |
363 | ||
364 | crypto_set_skcipher_spawn(&ctx->spawn, skcipher_crypto_instance(inst)); | |
89027579 HX |
365 | |
366 | mask = crypto_requires_off(algt->type, algt->mask, | |
367 | CRYPTO_ALG_NEED_FALLBACK | | |
368 | CRYPTO_ALG_ASYNC); | |
369 | ||
370 | err = crypto_grab_skcipher(&ctx->spawn, cipher_name, 0, mask); | |
f1c131b4 HX |
371 | if (err == -ENOENT) { |
372 | err = -ENAMETOOLONG; | |
373 | if (snprintf(ctx->name, CRYPTO_MAX_ALG_NAME, "ecb(%s)", | |
374 | cipher_name) >= CRYPTO_MAX_ALG_NAME) | |
375 | goto err_free_inst; | |
376 | ||
89027579 | 377 | err = crypto_grab_skcipher(&ctx->spawn, ctx->name, 0, mask); |
f1c131b4 HX |
378 | } |
379 | ||
f19f5111 | 380 | if (err) |
f1c131b4 | 381 | goto err_free_inst; |
f19f5111 | 382 | |
f1c131b4 | 383 | alg = crypto_skcipher_spawn_alg(&ctx->spawn); |
f19f5111 | 384 | |
f1c131b4 HX |
385 | err = -EINVAL; |
386 | if (alg->base.cra_blocksize != XTS_BLOCK_SIZE) | |
387 | goto err_drop_spawn; | |
f19f5111 | 388 | |
f1c131b4 HX |
389 | if (crypto_skcipher_alg_ivsize(alg)) |
390 | goto err_drop_spawn; | |
f19f5111 | 391 | |
f1c131b4 HX |
392 | err = crypto_inst_setname(skcipher_crypto_instance(inst), "xts", |
393 | &alg->base); | |
394 | if (err) | |
395 | goto err_drop_spawn; | |
f19f5111 | 396 | |
f1c131b4 HX |
397 | err = -EINVAL; |
398 | cipher_name = alg->base.cra_name; | |
f19f5111 | 399 | |
f1c131b4 HX |
400 | /* Alas we screwed up the naming so we have to mangle the |
401 | * cipher name. | |
402 | */ | |
403 | if (!strncmp(cipher_name, "ecb(", 4)) { | |
404 | unsigned len; | |
f19f5111 | 405 | |
f1c131b4 HX |
406 | len = strlcpy(ctx->name, cipher_name + 4, sizeof(ctx->name)); |
407 | if (len < 2 || len >= sizeof(ctx->name)) | |
408 | goto err_drop_spawn; | |
f19f5111 | 409 | |
f1c131b4 HX |
410 | if (ctx->name[len - 1] != ')') |
411 | goto err_drop_spawn; | |
f19f5111 | 412 | |
f1c131b4 | 413 | ctx->name[len - 1] = 0; |
f19f5111 | 414 | |
f1c131b4 | 415 | if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME, |
5125e4e8 CJ |
416 | "xts(%s)", ctx->name) >= CRYPTO_MAX_ALG_NAME) { |
417 | err = -ENAMETOOLONG; | |
418 | goto err_drop_spawn; | |
419 | } | |
f1c131b4 HX |
420 | } else |
421 | goto err_drop_spawn; | |
f19f5111 | 422 | |
f1c131b4 HX |
423 | inst->alg.base.cra_flags = alg->base.cra_flags & CRYPTO_ALG_ASYNC; |
424 | inst->alg.base.cra_priority = alg->base.cra_priority; | |
425 | inst->alg.base.cra_blocksize = XTS_BLOCK_SIZE; | |
426 | inst->alg.base.cra_alignmask = alg->base.cra_alignmask | | |
427 | (__alignof__(u64) - 1); | |
428 | ||
429 | inst->alg.ivsize = XTS_BLOCK_SIZE; | |
430 | inst->alg.min_keysize = crypto_skcipher_alg_min_keysize(alg) * 2; | |
431 | inst->alg.max_keysize = crypto_skcipher_alg_max_keysize(alg) * 2; | |
432 | ||
433 | inst->alg.base.cra_ctxsize = sizeof(struct priv); | |
434 | ||
435 | inst->alg.init = init_tfm; | |
436 | inst->alg.exit = exit_tfm; | |
437 | ||
438 | inst->alg.setkey = setkey; | |
439 | inst->alg.encrypt = encrypt; | |
440 | inst->alg.decrypt = decrypt; | |
441 | ||
442 | inst->free = free; | |
443 | ||
444 | err = skcipher_register_instance(tmpl, inst); | |
445 | if (err) | |
446 | goto err_drop_spawn; | |
447 | ||
448 | out: | |
449 | return err; | |
450 | ||
451 | err_drop_spawn: | |
452 | crypto_drop_skcipher(&ctx->spawn); | |
453 | err_free_inst: | |
f19f5111 | 454 | kfree(inst); |
f1c131b4 | 455 | goto out; |
f19f5111 RS |
456 | } |
457 | ||
458 | static struct crypto_template crypto_tmpl = { | |
459 | .name = "xts", | |
f1c131b4 | 460 | .create = create, |
f19f5111 RS |
461 | .module = THIS_MODULE, |
462 | }; | |
463 | ||
464 | static int __init crypto_module_init(void) | |
465 | { | |
466 | return crypto_register_template(&crypto_tmpl); | |
467 | } | |
468 | ||
469 | static void __exit crypto_module_exit(void) | |
470 | { | |
471 | crypto_unregister_template(&crypto_tmpl); | |
472 | } | |
473 | ||
c4741b23 | 474 | subsys_initcall(crypto_module_init); |
f19f5111 RS |
475 | module_exit(crypto_module_exit); |
476 | ||
477 | MODULE_LICENSE("GPL"); | |
478 | MODULE_DESCRIPTION("XTS block cipher mode"); | |
4943ba16 | 479 | MODULE_ALIAS_CRYPTO("xts"); |