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1// SPDX-License-Identifier: GPL-2.0-or-later
2/* XTS: as defined in IEEE1619/D16
3 * http://grouper.ieee.org/groups/1619/email/pdf00086.pdf
4 *
5 * Copyright (c) 2007 Rik Snel <rsnel@cube.dyndns.org>
6 *
7 * Based on ecb.c
8 * Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au>
9 */
10#include <crypto/internal/skcipher.h>
11#include <crypto/scatterwalk.h>
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
19#include <crypto/xts.h>
20#include <crypto/b128ops.h>
21#include <crypto/gf128mul.h>
22
23struct priv {
24 struct crypto_skcipher *child;
25 struct crypto_cipher *tweak;
26};
27
28struct xts_instance_ctx {
29 struct crypto_skcipher_spawn spawn;
30 char name[CRYPTO_MAX_ALG_NAME];
31};
32
33struct rctx {
34 le128 t;
35 struct scatterlist *tail;
36 struct scatterlist sg[2];
37 struct skcipher_request subreq;
38};
39
40static int setkey(struct crypto_skcipher *parent, const u8 *key,
41 unsigned int keylen)
42{
43 struct priv *ctx = crypto_skcipher_ctx(parent);
44 struct crypto_skcipher *child;
45 struct crypto_cipher *tweak;
46 int err;
47
48 err = xts_verify_key(parent, key, keylen);
49 if (err)
50 return err;
51
52 keylen /= 2;
53
54 /* we need two cipher instances: one to compute the initial 'tweak'
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 */
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) &
62 CRYPTO_TFM_REQ_MASK);
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);
66 if (err)
67 return err;
68
69 /* data cipher, uses Key1 i.e. the first half of *key */
70 child = ctx->child;
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);
77
78 return err;
79}
80
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 */
87static int xor_tweak(struct skcipher_request *req, bool second_pass, bool enc)
88{
89 struct rctx *rctx = skcipher_request_ctx(req);
90 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
91 const bool cts = (req->cryptlen % XTS_BLOCK_SIZE);
92 const int bs = XTS_BLOCK_SIZE;
93 struct skcipher_walk w;
94 le128 t = rctx->t;
95 int err;
96
97 if (second_pass) {
98 req = &rctx->subreq;
99 /* set to our TFM to enforce correct alignment: */
100 skcipher_request_set_tfm(req, tfm);
101 }
102 err = skcipher_walk_virt(&w, req, false);
103
104 while (w.nbytes) {
105 unsigned int avail = w.nbytes;
106 le128 *wsrc;
107 le128 *wdst;
108
109 wsrc = w.src.virt.addr;
110 wdst = w.dst.virt.addr;
111
112 do {
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
127 le128_xor(wdst++, &t, wsrc++);
128 gf128mul_x_ble(&t, &t);
129 } while ((avail -= bs) >= bs);
130
131 err = skcipher_walk_done(&w, avail);
132 }
133
134 return err;
135}
136
137static int xor_tweak_pre(struct skcipher_request *req, bool enc)
138{
139 return xor_tweak(req, false, enc);
140}
141
142static int xor_tweak_post(struct skcipher_request *req, bool enc)
143{
144 return xor_tweak(req, true, enc);
145}
146
147static void cts_done(struct crypto_async_request *areq, int err)
148{
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
163static 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;
199}
200
201static void encrypt_done(struct crypto_async_request *areq, int err)
202{
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);
219}
220
221static void decrypt_done(struct crypto_async_request *areq, int err)
222{
223 struct skcipher_request *req = areq->data;
224
225 if (!err) {
226 struct rctx *rctx = skcipher_request_ctx(req);
227
228 rctx->subreq.base.flags &= ~CRYPTO_TFM_REQ_MAY_SLEEP;
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 }
236 }
237
238 skcipher_request_complete(req, err);
239}
240
241static int init_crypt(struct skcipher_request *req, crypto_completion_t compl)
242{
243 struct priv *ctx = crypto_skcipher_ctx(crypto_skcipher_reqtfm(req));
244 struct rctx *rctx = skcipher_request_ctx(req);
245 struct skcipher_request *subreq = &rctx->subreq;
246
247 if (req->cryptlen < XTS_BLOCK_SIZE)
248 return -EINVAL;
249
250 skcipher_request_set_tfm(subreq, ctx->child);
251 skcipher_request_set_callback(subreq, req->base.flags, compl, req);
252 skcipher_request_set_crypt(subreq, req->dst, req->dst,
253 req->cryptlen & ~(XTS_BLOCK_SIZE - 1), NULL);
254
255 /* calculate first value of T */
256 crypto_cipher_encrypt_one(ctx->tweak, (u8 *)&rctx->t, req->iv);
257
258 return 0;
259}
260
261static int encrypt(struct skcipher_request *req)
262{
263 struct rctx *rctx = skcipher_request_ctx(req);
264 struct skcipher_request *subreq = &rctx->subreq;
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);
271
272 if (err || likely((req->cryptlen % XTS_BLOCK_SIZE) == 0))
273 return err;
274
275 return cts_final(req, crypto_skcipher_encrypt);
276}
277
278static int decrypt(struct skcipher_request *req)
279{
280 struct rctx *rctx = skcipher_request_ctx(req);
281 struct skcipher_request *subreq = &rctx->subreq;
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;
291
292 return cts_final(req, crypto_skcipher_decrypt);
293}
294
295static int init_tfm(struct crypto_skcipher *tfm)
296{
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;
302
303 child = crypto_spawn_skcipher(&ictx->spawn);
304 if (IS_ERR(child))
305 return PTR_ERR(child);
306
307 ctx->child = child;
308
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);
313 }
314
315 ctx->tweak = tweak;
316
317 crypto_skcipher_set_reqsize(tfm, crypto_skcipher_reqsize(child) +
318 sizeof(struct rctx));
319
320 return 0;
321}
322
323static void exit_tfm(struct crypto_skcipher *tfm)
324{
325 struct priv *ctx = crypto_skcipher_ctx(tfm);
326
327 crypto_free_skcipher(ctx->child);
328 crypto_free_cipher(ctx->tweak);
329}
330
331static void free(struct skcipher_instance *inst)
332{
333 crypto_drop_skcipher(skcipher_instance_ctx(inst));
334 kfree(inst);
335}
336
337static int create(struct crypto_template *tmpl, struct rtattr **tb)
338{
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;
344 u32 mask;
345 int err;
346
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));
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);
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
377 err = crypto_grab_skcipher(&ctx->spawn, ctx->name, 0, mask);
378 }
379
380 if (err)
381 goto err_free_inst;
382
383 alg = crypto_skcipher_spawn_alg(&ctx->spawn);
384
385 err = -EINVAL;
386 if (alg->base.cra_blocksize != XTS_BLOCK_SIZE)
387 goto err_drop_spawn;
388
389 if (crypto_skcipher_alg_ivsize(alg))
390 goto err_drop_spawn;
391
392 err = crypto_inst_setname(skcipher_crypto_instance(inst), "xts",
393 &alg->base);
394 if (err)
395 goto err_drop_spawn;
396
397 err = -EINVAL;
398 cipher_name = alg->base.cra_name;
399
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;
405
406 len = strlcpy(ctx->name, cipher_name + 4, sizeof(ctx->name));
407 if (len < 2 || len >= sizeof(ctx->name))
408 goto err_drop_spawn;
409
410 if (ctx->name[len - 1] != ')')
411 goto err_drop_spawn;
412
413 ctx->name[len - 1] = 0;
414
415 if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
416 "xts(%s)", ctx->name) >= CRYPTO_MAX_ALG_NAME) {
417 err = -ENAMETOOLONG;
418 goto err_drop_spawn;
419 }
420 } else
421 goto err_drop_spawn;
422
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
448out:
449 return err;
450
451err_drop_spawn:
452 crypto_drop_skcipher(&ctx->spawn);
453err_free_inst:
454 kfree(inst);
455 goto out;
456}
457
458static struct crypto_template crypto_tmpl = {
459 .name = "xts",
460 .create = create,
461 .module = THIS_MODULE,
462};
463
464static int __init crypto_module_init(void)
465{
466 return crypto_register_template(&crypto_tmpl);
467}
468
469static void __exit crypto_module_exit(void)
470{
471 crypto_unregister_template(&crypto_tmpl);
472}
473
474subsys_initcall(crypto_module_init);
475module_exit(crypto_module_exit);
476
477MODULE_LICENSE("GPL");
478MODULE_DESCRIPTION("XTS block cipher mode");
479MODULE_ALIAS_CRYPTO("xts");
1/* XTS: as defined in IEEE1619/D16
2 * http://grouper.ieee.org/groups/1619/email/pdf00086.pdf
3 * (sector sizes which are not a multiple of 16 bytes are,
4 * however currently unsupported)
5 *
6 * Copyright (c) 2007 Rik Snel <rsnel@cube.dyndns.org>
7 *
8 * Based om ecb.c
9 * Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au>
10 *
11 * This program is free software; you can redistribute it and/or modify it
12 * under the terms of the GNU General Public License as published by the Free
13 * Software Foundation; either version 2 of the License, or (at your option)
14 * any later version.
15 */
16#include <crypto/algapi.h>
17#include <linux/err.h>
18#include <linux/init.h>
19#include <linux/kernel.h>
20#include <linux/module.h>
21#include <linux/scatterlist.h>
22#include <linux/slab.h>
23
24#include <crypto/xts.h>
25#include <crypto/b128ops.h>
26#include <crypto/gf128mul.h>
27
28struct priv {
29 struct crypto_cipher *child;
30 struct crypto_cipher *tweak;
31};
32
33static int setkey(struct crypto_tfm *parent, const u8 *key,
34 unsigned int keylen)
35{
36 struct priv *ctx = crypto_tfm_ctx(parent);
37 struct crypto_cipher *child = ctx->tweak;
38 int err;
39
40 err = xts_check_key(parent, key, keylen);
41 if (err)
42 return err;
43
44 /* we need two cipher instances: one to compute the initial 'tweak'
45 * by encrypting the IV (usually the 'plain' iv) and the other
46 * one to encrypt and decrypt the data */
47
48 /* tweak cipher, uses Key2 i.e. the second half of *key */
49 crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
50 crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &
51 CRYPTO_TFM_REQ_MASK);
52 err = crypto_cipher_setkey(child, key + keylen/2, keylen/2);
53 if (err)
54 return err;
55
56 crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &
57 CRYPTO_TFM_RES_MASK);
58
59 child = ctx->child;
60
61 /* data cipher, uses Key1 i.e. the first half of *key */
62 crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
63 crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &
64 CRYPTO_TFM_REQ_MASK);
65 err = crypto_cipher_setkey(child, key, keylen/2);
66 if (err)
67 return err;
68
69 crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &
70 CRYPTO_TFM_RES_MASK);
71
72 return 0;
73}
74
75struct sinfo {
76 be128 *t;
77 struct crypto_tfm *tfm;
78 void (*fn)(struct crypto_tfm *, u8 *, const u8 *);
79};
80
81static inline void xts_round(struct sinfo *s, void *dst, const void *src)
82{
83 be128_xor(dst, s->t, src); /* PP <- T xor P */
84 s->fn(s->tfm, dst, dst); /* CC <- E(Key1,PP) */
85 be128_xor(dst, dst, s->t); /* C <- T xor CC */
86}
87
88static int crypt(struct blkcipher_desc *d,
89 struct blkcipher_walk *w, struct priv *ctx,
90 void (*tw)(struct crypto_tfm *, u8 *, const u8 *),
91 void (*fn)(struct crypto_tfm *, u8 *, const u8 *))
92{
93 int err;
94 unsigned int avail;
95 const int bs = XTS_BLOCK_SIZE;
96 struct sinfo s = {
97 .tfm = crypto_cipher_tfm(ctx->child),
98 .fn = fn
99 };
100 u8 *wsrc;
101 u8 *wdst;
102
103 err = blkcipher_walk_virt(d, w);
104 if (!w->nbytes)
105 return err;
106
107 s.t = (be128 *)w->iv;
108 avail = w->nbytes;
109
110 wsrc = w->src.virt.addr;
111 wdst = w->dst.virt.addr;
112
113 /* calculate first value of T */
114 tw(crypto_cipher_tfm(ctx->tweak), w->iv, w->iv);
115
116 goto first;
117
118 for (;;) {
119 do {
120 gf128mul_x_ble(s.t, s.t);
121
122first:
123 xts_round(&s, wdst, wsrc);
124
125 wsrc += bs;
126 wdst += bs;
127 } while ((avail -= bs) >= bs);
128
129 err = blkcipher_walk_done(d, w, avail);
130 if (!w->nbytes)
131 break;
132
133 avail = w->nbytes;
134
135 wsrc = w->src.virt.addr;
136 wdst = w->dst.virt.addr;
137 }
138
139 return err;
140}
141
142static int encrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
143 struct scatterlist *src, unsigned int nbytes)
144{
145 struct priv *ctx = crypto_blkcipher_ctx(desc->tfm);
146 struct blkcipher_walk w;
147
148 blkcipher_walk_init(&w, dst, src, nbytes);
149 return crypt(desc, &w, ctx, crypto_cipher_alg(ctx->tweak)->cia_encrypt,
150 crypto_cipher_alg(ctx->child)->cia_encrypt);
151}
152
153static int decrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
154 struct scatterlist *src, unsigned int nbytes)
155{
156 struct priv *ctx = crypto_blkcipher_ctx(desc->tfm);
157 struct blkcipher_walk w;
158
159 blkcipher_walk_init(&w, dst, src, nbytes);
160 return crypt(desc, &w, ctx, crypto_cipher_alg(ctx->tweak)->cia_encrypt,
161 crypto_cipher_alg(ctx->child)->cia_decrypt);
162}
163
164int xts_crypt(struct blkcipher_desc *desc, struct scatterlist *sdst,
165 struct scatterlist *ssrc, unsigned int nbytes,
166 struct xts_crypt_req *req)
167{
168 const unsigned int bsize = XTS_BLOCK_SIZE;
169 const unsigned int max_blks = req->tbuflen / bsize;
170 struct blkcipher_walk walk;
171 unsigned int nblocks;
172 be128 *src, *dst, *t;
173 be128 *t_buf = req->tbuf;
174 int err, i;
175
176 BUG_ON(max_blks < 1);
177
178 blkcipher_walk_init(&walk, sdst, ssrc, nbytes);
179
180 err = blkcipher_walk_virt(desc, &walk);
181 nbytes = walk.nbytes;
182 if (!nbytes)
183 return err;
184
185 nblocks = min(nbytes / bsize, max_blks);
186 src = (be128 *)walk.src.virt.addr;
187 dst = (be128 *)walk.dst.virt.addr;
188
189 /* calculate first value of T */
190 req->tweak_fn(req->tweak_ctx, (u8 *)&t_buf[0], walk.iv);
191
192 i = 0;
193 goto first;
194
195 for (;;) {
196 do {
197 for (i = 0; i < nblocks; i++) {
198 gf128mul_x_ble(&t_buf[i], t);
199first:
200 t = &t_buf[i];
201
202 /* PP <- T xor P */
203 be128_xor(dst + i, t, src + i);
204 }
205
206 /* CC <- E(Key2,PP) */
207 req->crypt_fn(req->crypt_ctx, (u8 *)dst,
208 nblocks * bsize);
209
210 /* C <- T xor CC */
211 for (i = 0; i < nblocks; i++)
212 be128_xor(dst + i, dst + i, &t_buf[i]);
213
214 src += nblocks;
215 dst += nblocks;
216 nbytes -= nblocks * bsize;
217 nblocks = min(nbytes / bsize, max_blks);
218 } while (nblocks > 0);
219
220 *(be128 *)walk.iv = *t;
221
222 err = blkcipher_walk_done(desc, &walk, nbytes);
223 nbytes = walk.nbytes;
224 if (!nbytes)
225 break;
226
227 nblocks = min(nbytes / bsize, max_blks);
228 src = (be128 *)walk.src.virt.addr;
229 dst = (be128 *)walk.dst.virt.addr;
230 }
231
232 return err;
233}
234EXPORT_SYMBOL_GPL(xts_crypt);
235
236static int init_tfm(struct crypto_tfm *tfm)
237{
238 struct crypto_cipher *cipher;
239 struct crypto_instance *inst = (void *)tfm->__crt_alg;
240 struct crypto_spawn *spawn = crypto_instance_ctx(inst);
241 struct priv *ctx = crypto_tfm_ctx(tfm);
242 u32 *flags = &tfm->crt_flags;
243
244 cipher = crypto_spawn_cipher(spawn);
245 if (IS_ERR(cipher))
246 return PTR_ERR(cipher);
247
248 if (crypto_cipher_blocksize(cipher) != XTS_BLOCK_SIZE) {
249 *flags |= CRYPTO_TFM_RES_BAD_BLOCK_LEN;
250 crypto_free_cipher(cipher);
251 return -EINVAL;
252 }
253
254 ctx->child = cipher;
255
256 cipher = crypto_spawn_cipher(spawn);
257 if (IS_ERR(cipher)) {
258 crypto_free_cipher(ctx->child);
259 return PTR_ERR(cipher);
260 }
261
262 /* this check isn't really needed, leave it here just in case */
263 if (crypto_cipher_blocksize(cipher) != XTS_BLOCK_SIZE) {
264 crypto_free_cipher(cipher);
265 crypto_free_cipher(ctx->child);
266 *flags |= CRYPTO_TFM_RES_BAD_BLOCK_LEN;
267 return -EINVAL;
268 }
269
270 ctx->tweak = cipher;
271
272 return 0;
273}
274
275static void exit_tfm(struct crypto_tfm *tfm)
276{
277 struct priv *ctx = crypto_tfm_ctx(tfm);
278 crypto_free_cipher(ctx->child);
279 crypto_free_cipher(ctx->tweak);
280}
281
282static struct crypto_instance *alloc(struct rtattr **tb)
283{
284 struct crypto_instance *inst;
285 struct crypto_alg *alg;
286 int err;
287
288 err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER);
289 if (err)
290 return ERR_PTR(err);
291
292 alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER,
293 CRYPTO_ALG_TYPE_MASK);
294 if (IS_ERR(alg))
295 return ERR_CAST(alg);
296
297 inst = crypto_alloc_instance("xts", alg);
298 if (IS_ERR(inst))
299 goto out_put_alg;
300
301 inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER;
302 inst->alg.cra_priority = alg->cra_priority;
303 inst->alg.cra_blocksize = alg->cra_blocksize;
304
305 if (alg->cra_alignmask < 7)
306 inst->alg.cra_alignmask = 7;
307 else
308 inst->alg.cra_alignmask = alg->cra_alignmask;
309
310 inst->alg.cra_type = &crypto_blkcipher_type;
311
312 inst->alg.cra_blkcipher.ivsize = alg->cra_blocksize;
313 inst->alg.cra_blkcipher.min_keysize =
314 2 * alg->cra_cipher.cia_min_keysize;
315 inst->alg.cra_blkcipher.max_keysize =
316 2 * alg->cra_cipher.cia_max_keysize;
317
318 inst->alg.cra_ctxsize = sizeof(struct priv);
319
320 inst->alg.cra_init = init_tfm;
321 inst->alg.cra_exit = exit_tfm;
322
323 inst->alg.cra_blkcipher.setkey = setkey;
324 inst->alg.cra_blkcipher.encrypt = encrypt;
325 inst->alg.cra_blkcipher.decrypt = decrypt;
326
327out_put_alg:
328 crypto_mod_put(alg);
329 return inst;
330}
331
332static void free(struct crypto_instance *inst)
333{
334 crypto_drop_spawn(crypto_instance_ctx(inst));
335 kfree(inst);
336}
337
338static struct crypto_template crypto_tmpl = {
339 .name = "xts",
340 .alloc = alloc,
341 .free = free,
342 .module = THIS_MODULE,
343};
344
345static int __init crypto_module_init(void)
346{
347 return crypto_register_template(&crypto_tmpl);
348}
349
350static void __exit crypto_module_exit(void)
351{
352 crypto_unregister_template(&crypto_tmpl);
353}
354
355module_init(crypto_module_init);
356module_exit(crypto_module_exit);
357
358MODULE_LICENSE("GPL");
359MODULE_DESCRIPTION("XTS block cipher mode");
360MODULE_ALIAS_CRYPTO("xts");