Commit | Line | Data |
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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 | |
4 | * (sector sizes which are not a multiple of 16 bytes are, | |
5 | * however currently unsupported) | |
6 | * | |
7 | * Copyright (c) 2007 Rik Snel <rsnel@cube.dyndns.org> | |
8 | * | |
ddbc7361 | 9 | * Based on ecb.c |
f19f5111 | 10 | * Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au> |
f19f5111 | 11 | */ |
f1c131b4 HX |
12 | #include <crypto/internal/skcipher.h> |
13 | #include <crypto/scatterwalk.h> | |
f19f5111 RS |
14 | #include <linux/err.h> |
15 | #include <linux/init.h> | |
16 | #include <linux/kernel.h> | |
17 | #include <linux/module.h> | |
18 | #include <linux/scatterlist.h> | |
19 | #include <linux/slab.h> | |
20 | ||
ce004556 | 21 | #include <crypto/xts.h> |
f19f5111 RS |
22 | #include <crypto/b128ops.h> |
23 | #include <crypto/gf128mul.h> | |
24 | ||
25 | struct priv { | |
f1c131b4 | 26 | struct crypto_skcipher *child; |
f19f5111 RS |
27 | struct crypto_cipher *tweak; |
28 | }; | |
29 | ||
f1c131b4 HX |
30 | struct xts_instance_ctx { |
31 | struct crypto_skcipher_spawn spawn; | |
32 | char name[CRYPTO_MAX_ALG_NAME]; | |
33 | }; | |
34 | ||
35 | struct rctx { | |
e55318c8 | 36 | le128 t; |
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 | */ | |
87 | static int xor_tweak(struct skcipher_request *req, bool second_pass) | |
f1c131b4 HX |
88 | { |
89 | struct rctx *rctx = skcipher_request_ctx(req); | |
78105c7e | 90 | struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); |
f1c131b4 HX |
91 | const int bs = XTS_BLOCK_SIZE; |
92 | struct skcipher_walk w; | |
78105c7e | 93 | le128 t = rctx->t; |
f1c131b4 | 94 | int err; |
f19f5111 | 95 | |
78105c7e OM |
96 | if (second_pass) { |
97 | req = &rctx->subreq; | |
98 | /* set to our TFM to enforce correct alignment: */ | |
99 | skcipher_request_set_tfm(req, tfm); | |
f1c131b4 | 100 | } |
78105c7e | 101 | err = skcipher_walk_virt(&w, req, false); |
f19f5111 | 102 | |
f1c131b4 HX |
103 | while (w.nbytes) { |
104 | unsigned int avail = w.nbytes; | |
e55318c8 OM |
105 | le128 *wsrc; |
106 | le128 *wdst; | |
f19f5111 | 107 | |
f1c131b4 HX |
108 | wsrc = w.src.virt.addr; |
109 | wdst = w.dst.virt.addr; | |
f19f5111 | 110 | |
f1c131b4 | 111 | do { |
78105c7e OM |
112 | le128_xor(wdst++, &t, wsrc++); |
113 | gf128mul_x_ble(&t, &t); | |
f19f5111 RS |
114 | } while ((avail -= bs) >= bs); |
115 | ||
f1c131b4 HX |
116 | err = skcipher_walk_done(&w, avail); |
117 | } | |
118 | ||
f19f5111 RS |
119 | return err; |
120 | } | |
121 | ||
78105c7e | 122 | static int xor_tweak_pre(struct skcipher_request *req) |
f19f5111 | 123 | { |
78105c7e | 124 | return xor_tweak(req, false); |
f1c131b4 HX |
125 | } |
126 | ||
78105c7e | 127 | static int xor_tweak_post(struct skcipher_request *req) |
f1c131b4 | 128 | { |
78105c7e | 129 | return xor_tweak(req, true); |
f1c131b4 HX |
130 | } |
131 | ||
78105c7e | 132 | static void crypt_done(struct crypto_async_request *areq, int err) |
f1c131b4 HX |
133 | { |
134 | struct skcipher_request *req = areq->data; | |
aa4a829b | 135 | |
44427c0f HX |
136 | if (!err) { |
137 | struct rctx *rctx = skcipher_request_ctx(req); | |
138 | ||
139 | rctx->subreq.base.flags &= ~CRYPTO_TFM_REQ_MAY_SLEEP; | |
78105c7e | 140 | err = xor_tweak_post(req); |
44427c0f | 141 | } |
f1c131b4 | 142 | |
f1c131b4 HX |
143 | skcipher_request_complete(req, err); |
144 | } | |
145 | ||
78105c7e | 146 | static void init_crypt(struct skcipher_request *req) |
f1c131b4 | 147 | { |
78105c7e | 148 | struct priv *ctx = crypto_skcipher_ctx(crypto_skcipher_reqtfm(req)); |
f1c131b4 | 149 | struct rctx *rctx = skcipher_request_ctx(req); |
78105c7e | 150 | struct skcipher_request *subreq = &rctx->subreq; |
f1c131b4 | 151 | |
78105c7e OM |
152 | skcipher_request_set_tfm(subreq, ctx->child); |
153 | skcipher_request_set_callback(subreq, req->base.flags, crypt_done, req); | |
154 | skcipher_request_set_crypt(subreq, req->dst, req->dst, | |
155 | req->cryptlen, NULL); | |
f1c131b4 | 156 | |
78105c7e OM |
157 | /* calculate first value of T */ |
158 | crypto_cipher_encrypt_one(ctx->tweak, (u8 *)&rctx->t, req->iv); | |
f1c131b4 HX |
159 | } |
160 | ||
78105c7e | 161 | static int encrypt(struct skcipher_request *req) |
f1c131b4 | 162 | { |
78105c7e OM |
163 | struct rctx *rctx = skcipher_request_ctx(req); |
164 | struct skcipher_request *subreq = &rctx->subreq; | |
f1c131b4 | 165 | |
78105c7e OM |
166 | init_crypt(req); |
167 | return xor_tweak_pre(req) ?: | |
168 | crypto_skcipher_encrypt(subreq) ?: | |
169 | xor_tweak_post(req); | |
f1c131b4 HX |
170 | } |
171 | ||
172 | static int decrypt(struct skcipher_request *req) | |
173 | { | |
78105c7e OM |
174 | struct rctx *rctx = skcipher_request_ctx(req); |
175 | struct skcipher_request *subreq = &rctx->subreq; | |
176 | ||
177 | init_crypt(req); | |
178 | return xor_tweak_pre(req) ?: | |
179 | crypto_skcipher_decrypt(subreq) ?: | |
180 | xor_tweak_post(req); | |
f19f5111 RS |
181 | } |
182 | ||
f1c131b4 | 183 | static int init_tfm(struct crypto_skcipher *tfm) |
f19f5111 | 184 | { |
f1c131b4 HX |
185 | struct skcipher_instance *inst = skcipher_alg_instance(tfm); |
186 | struct xts_instance_ctx *ictx = skcipher_instance_ctx(inst); | |
187 | struct priv *ctx = crypto_skcipher_ctx(tfm); | |
188 | struct crypto_skcipher *child; | |
189 | struct crypto_cipher *tweak; | |
f19f5111 | 190 | |
f1c131b4 HX |
191 | child = crypto_spawn_skcipher(&ictx->spawn); |
192 | if (IS_ERR(child)) | |
193 | return PTR_ERR(child); | |
f19f5111 | 194 | |
f1c131b4 | 195 | ctx->child = child; |
f19f5111 | 196 | |
f1c131b4 HX |
197 | tweak = crypto_alloc_cipher(ictx->name, 0, 0); |
198 | if (IS_ERR(tweak)) { | |
199 | crypto_free_skcipher(ctx->child); | |
200 | return PTR_ERR(tweak); | |
f19f5111 RS |
201 | } |
202 | ||
f1c131b4 HX |
203 | ctx->tweak = tweak; |
204 | ||
205 | crypto_skcipher_set_reqsize(tfm, crypto_skcipher_reqsize(child) + | |
206 | sizeof(struct rctx)); | |
f19f5111 RS |
207 | |
208 | return 0; | |
209 | } | |
210 | ||
f1c131b4 | 211 | static void exit_tfm(struct crypto_skcipher *tfm) |
f19f5111 | 212 | { |
f1c131b4 HX |
213 | struct priv *ctx = crypto_skcipher_ctx(tfm); |
214 | ||
215 | crypto_free_skcipher(ctx->child); | |
f19f5111 RS |
216 | crypto_free_cipher(ctx->tweak); |
217 | } | |
218 | ||
f1c131b4 HX |
219 | static void free(struct skcipher_instance *inst) |
220 | { | |
221 | crypto_drop_skcipher(skcipher_instance_ctx(inst)); | |
222 | kfree(inst); | |
223 | } | |
224 | ||
225 | static int create(struct crypto_template *tmpl, struct rtattr **tb) | |
f19f5111 | 226 | { |
f1c131b4 HX |
227 | struct skcipher_instance *inst; |
228 | struct crypto_attr_type *algt; | |
229 | struct xts_instance_ctx *ctx; | |
230 | struct skcipher_alg *alg; | |
231 | const char *cipher_name; | |
89027579 | 232 | u32 mask; |
f19f5111 RS |
233 | int err; |
234 | ||
f1c131b4 HX |
235 | algt = crypto_get_attr_type(tb); |
236 | if (IS_ERR(algt)) | |
237 | return PTR_ERR(algt); | |
238 | ||
239 | if ((algt->type ^ CRYPTO_ALG_TYPE_SKCIPHER) & algt->mask) | |
240 | return -EINVAL; | |
241 | ||
242 | cipher_name = crypto_attr_alg_name(tb[1]); | |
243 | if (IS_ERR(cipher_name)) | |
244 | return PTR_ERR(cipher_name); | |
245 | ||
246 | inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL); | |
247 | if (!inst) | |
248 | return -ENOMEM; | |
249 | ||
250 | ctx = skcipher_instance_ctx(inst); | |
251 | ||
252 | crypto_set_skcipher_spawn(&ctx->spawn, skcipher_crypto_instance(inst)); | |
89027579 HX |
253 | |
254 | mask = crypto_requires_off(algt->type, algt->mask, | |
255 | CRYPTO_ALG_NEED_FALLBACK | | |
256 | CRYPTO_ALG_ASYNC); | |
257 | ||
258 | err = crypto_grab_skcipher(&ctx->spawn, cipher_name, 0, mask); | |
f1c131b4 HX |
259 | if (err == -ENOENT) { |
260 | err = -ENAMETOOLONG; | |
261 | if (snprintf(ctx->name, CRYPTO_MAX_ALG_NAME, "ecb(%s)", | |
262 | cipher_name) >= CRYPTO_MAX_ALG_NAME) | |
263 | goto err_free_inst; | |
264 | ||
89027579 | 265 | err = crypto_grab_skcipher(&ctx->spawn, ctx->name, 0, mask); |
f1c131b4 HX |
266 | } |
267 | ||
f19f5111 | 268 | if (err) |
f1c131b4 | 269 | goto err_free_inst; |
f19f5111 | 270 | |
f1c131b4 | 271 | alg = crypto_skcipher_spawn_alg(&ctx->spawn); |
f19f5111 | 272 | |
f1c131b4 HX |
273 | err = -EINVAL; |
274 | if (alg->base.cra_blocksize != XTS_BLOCK_SIZE) | |
275 | goto err_drop_spawn; | |
f19f5111 | 276 | |
f1c131b4 HX |
277 | if (crypto_skcipher_alg_ivsize(alg)) |
278 | goto err_drop_spawn; | |
f19f5111 | 279 | |
f1c131b4 HX |
280 | err = crypto_inst_setname(skcipher_crypto_instance(inst), "xts", |
281 | &alg->base); | |
282 | if (err) | |
283 | goto err_drop_spawn; | |
f19f5111 | 284 | |
f1c131b4 HX |
285 | err = -EINVAL; |
286 | cipher_name = alg->base.cra_name; | |
f19f5111 | 287 | |
f1c131b4 HX |
288 | /* Alas we screwed up the naming so we have to mangle the |
289 | * cipher name. | |
290 | */ | |
291 | if (!strncmp(cipher_name, "ecb(", 4)) { | |
292 | unsigned len; | |
f19f5111 | 293 | |
f1c131b4 HX |
294 | len = strlcpy(ctx->name, cipher_name + 4, sizeof(ctx->name)); |
295 | if (len < 2 || len >= sizeof(ctx->name)) | |
296 | goto err_drop_spawn; | |
f19f5111 | 297 | |
f1c131b4 HX |
298 | if (ctx->name[len - 1] != ')') |
299 | goto err_drop_spawn; | |
f19f5111 | 300 | |
f1c131b4 | 301 | ctx->name[len - 1] = 0; |
f19f5111 | 302 | |
f1c131b4 | 303 | if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME, |
5125e4e8 CJ |
304 | "xts(%s)", ctx->name) >= CRYPTO_MAX_ALG_NAME) { |
305 | err = -ENAMETOOLONG; | |
306 | goto err_drop_spawn; | |
307 | } | |
f1c131b4 HX |
308 | } else |
309 | goto err_drop_spawn; | |
f19f5111 | 310 | |
f1c131b4 HX |
311 | inst->alg.base.cra_flags = alg->base.cra_flags & CRYPTO_ALG_ASYNC; |
312 | inst->alg.base.cra_priority = alg->base.cra_priority; | |
313 | inst->alg.base.cra_blocksize = XTS_BLOCK_SIZE; | |
314 | inst->alg.base.cra_alignmask = alg->base.cra_alignmask | | |
315 | (__alignof__(u64) - 1); | |
316 | ||
317 | inst->alg.ivsize = XTS_BLOCK_SIZE; | |
318 | inst->alg.min_keysize = crypto_skcipher_alg_min_keysize(alg) * 2; | |
319 | inst->alg.max_keysize = crypto_skcipher_alg_max_keysize(alg) * 2; | |
320 | ||
321 | inst->alg.base.cra_ctxsize = sizeof(struct priv); | |
322 | ||
323 | inst->alg.init = init_tfm; | |
324 | inst->alg.exit = exit_tfm; | |
325 | ||
326 | inst->alg.setkey = setkey; | |
327 | inst->alg.encrypt = encrypt; | |
328 | inst->alg.decrypt = decrypt; | |
329 | ||
330 | inst->free = free; | |
331 | ||
332 | err = skcipher_register_instance(tmpl, inst); | |
333 | if (err) | |
334 | goto err_drop_spawn; | |
335 | ||
336 | out: | |
337 | return err; | |
338 | ||
339 | err_drop_spawn: | |
340 | crypto_drop_skcipher(&ctx->spawn); | |
341 | err_free_inst: | |
f19f5111 | 342 | kfree(inst); |
f1c131b4 | 343 | goto out; |
f19f5111 RS |
344 | } |
345 | ||
346 | static struct crypto_template crypto_tmpl = { | |
347 | .name = "xts", | |
f1c131b4 | 348 | .create = create, |
f19f5111 RS |
349 | .module = THIS_MODULE, |
350 | }; | |
351 | ||
352 | static int __init crypto_module_init(void) | |
353 | { | |
354 | return crypto_register_template(&crypto_tmpl); | |
355 | } | |
356 | ||
357 | static void __exit crypto_module_exit(void) | |
358 | { | |
359 | crypto_unregister_template(&crypto_tmpl); | |
360 | } | |
361 | ||
c4741b23 | 362 | subsys_initcall(crypto_module_init); |
f19f5111 RS |
363 | module_exit(crypto_module_exit); |
364 | ||
365 | MODULE_LICENSE("GPL"); | |
366 | MODULE_DESCRIPTION("XTS block cipher mode"); | |
4943ba16 | 367 | MODULE_ALIAS_CRYPTO("xts"); |