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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/cipher.h>
11#include <crypto/internal/skcipher.h>
12#include <crypto/scatterwalk.h>
13#include <linux/err.h>
14#include <linux/init.h>
15#include <linux/kernel.h>
16#include <linux/module.h>
17#include <linux/scatterlist.h>
18#include <linux/slab.h>
19
20#include <crypto/xts.h>
21#include <crypto/b128ops.h>
22#include <crypto/gf128mul.h>
23
24struct xts_tfm_ctx {
25 struct crypto_skcipher *child;
26 struct crypto_cipher *tweak;
27};
28
29struct xts_instance_ctx {
30 struct crypto_skcipher_spawn spawn;
31 struct crypto_cipher_spawn tweak_spawn;
32};
33
34struct xts_request_ctx {
35 le128 t;
36 struct scatterlist *tail;
37 struct scatterlist sg[2];
38 struct skcipher_request subreq;
39};
40
41static int xts_setkey(struct crypto_skcipher *parent, const u8 *key,
42 unsigned int keylen)
43{
44 struct xts_tfm_ctx *ctx = crypto_skcipher_ctx(parent);
45 struct crypto_skcipher *child;
46 struct crypto_cipher *tweak;
47 int err;
48
49 err = xts_verify_key(parent, key, keylen);
50 if (err)
51 return err;
52
53 keylen /= 2;
54
55 /* we need two cipher instances: one to compute the initial 'tweak'
56 * by encrypting the IV (usually the 'plain' iv) and the other
57 * one to encrypt and decrypt the data */
58
59 /* tweak cipher, uses Key2 i.e. the second half of *key */
60 tweak = ctx->tweak;
61 crypto_cipher_clear_flags(tweak, CRYPTO_TFM_REQ_MASK);
62 crypto_cipher_set_flags(tweak, crypto_skcipher_get_flags(parent) &
63 CRYPTO_TFM_REQ_MASK);
64 err = crypto_cipher_setkey(tweak, key + keylen, keylen);
65 if (err)
66 return err;
67
68 /* data cipher, uses Key1 i.e. the first half of *key */
69 child = ctx->child;
70 crypto_skcipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
71 crypto_skcipher_set_flags(child, crypto_skcipher_get_flags(parent) &
72 CRYPTO_TFM_REQ_MASK);
73 return crypto_skcipher_setkey(child, key, keylen);
74}
75
76/*
77 * We compute the tweak masks twice (both before and after the ECB encryption or
78 * decryption) to avoid having to allocate a temporary buffer and/or make
79 * mutliple calls to the 'ecb(..)' instance, which usually would be slower than
80 * just doing the gf128mul_x_ble() calls again.
81 */
82static int xts_xor_tweak(struct skcipher_request *req, bool second_pass,
83 bool enc)
84{
85 struct xts_request_ctx *rctx = skcipher_request_ctx(req);
86 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
87 const bool cts = (req->cryptlen % XTS_BLOCK_SIZE);
88 const int bs = XTS_BLOCK_SIZE;
89 struct skcipher_walk w;
90 le128 t = rctx->t;
91 int err;
92
93 if (second_pass) {
94 req = &rctx->subreq;
95 /* set to our TFM to enforce correct alignment: */
96 skcipher_request_set_tfm(req, tfm);
97 }
98 err = skcipher_walk_virt(&w, req, false);
99
100 while (w.nbytes) {
101 unsigned int avail = w.nbytes;
102 le128 *wsrc;
103 le128 *wdst;
104
105 wsrc = w.src.virt.addr;
106 wdst = w.dst.virt.addr;
107
108 do {
109 if (unlikely(cts) &&
110 w.total - w.nbytes + avail < 2 * XTS_BLOCK_SIZE) {
111 if (!enc) {
112 if (second_pass)
113 rctx->t = t;
114 gf128mul_x_ble(&t, &t);
115 }
116 le128_xor(wdst, &t, wsrc);
117 if (enc && second_pass)
118 gf128mul_x_ble(&rctx->t, &t);
119 skcipher_walk_done(&w, avail - bs);
120 return 0;
121 }
122
123 le128_xor(wdst++, &t, wsrc++);
124 gf128mul_x_ble(&t, &t);
125 } while ((avail -= bs) >= bs);
126
127 err = skcipher_walk_done(&w, avail);
128 }
129
130 return err;
131}
132
133static int xts_xor_tweak_pre(struct skcipher_request *req, bool enc)
134{
135 return xts_xor_tweak(req, false, enc);
136}
137
138static int xts_xor_tweak_post(struct skcipher_request *req, bool enc)
139{
140 return xts_xor_tweak(req, true, enc);
141}
142
143static void xts_cts_done(void *data, int err)
144{
145 struct skcipher_request *req = data;
146 le128 b;
147
148 if (!err) {
149 struct xts_request_ctx *rctx = skcipher_request_ctx(req);
150
151 scatterwalk_map_and_copy(&b, rctx->tail, 0, XTS_BLOCK_SIZE, 0);
152 le128_xor(&b, &rctx->t, &b);
153 scatterwalk_map_and_copy(&b, rctx->tail, 0, XTS_BLOCK_SIZE, 1);
154 }
155
156 skcipher_request_complete(req, err);
157}
158
159static int xts_cts_final(struct skcipher_request *req,
160 int (*crypt)(struct skcipher_request *req))
161{
162 const struct xts_tfm_ctx *ctx =
163 crypto_skcipher_ctx(crypto_skcipher_reqtfm(req));
164 int offset = req->cryptlen & ~(XTS_BLOCK_SIZE - 1);
165 struct xts_request_ctx *rctx = skcipher_request_ctx(req);
166 struct skcipher_request *subreq = &rctx->subreq;
167 int tail = req->cryptlen % XTS_BLOCK_SIZE;
168 le128 b[2];
169 int err;
170
171 rctx->tail = scatterwalk_ffwd(rctx->sg, req->dst,
172 offset - XTS_BLOCK_SIZE);
173
174 scatterwalk_map_and_copy(b, rctx->tail, 0, XTS_BLOCK_SIZE, 0);
175 b[1] = b[0];
176 scatterwalk_map_and_copy(b, req->src, offset, tail, 0);
177
178 le128_xor(b, &rctx->t, b);
179
180 scatterwalk_map_and_copy(b, rctx->tail, 0, XTS_BLOCK_SIZE + tail, 1);
181
182 skcipher_request_set_tfm(subreq, ctx->child);
183 skcipher_request_set_callback(subreq, req->base.flags, xts_cts_done,
184 req);
185 skcipher_request_set_crypt(subreq, rctx->tail, rctx->tail,
186 XTS_BLOCK_SIZE, NULL);
187
188 err = crypt(subreq);
189 if (err)
190 return err;
191
192 scatterwalk_map_and_copy(b, rctx->tail, 0, XTS_BLOCK_SIZE, 0);
193 le128_xor(b, &rctx->t, b);
194 scatterwalk_map_and_copy(b, rctx->tail, 0, XTS_BLOCK_SIZE, 1);
195
196 return 0;
197}
198
199static void xts_encrypt_done(void *data, int err)
200{
201 struct skcipher_request *req = data;
202
203 if (!err) {
204 struct xts_request_ctx *rctx = skcipher_request_ctx(req);
205
206 rctx->subreq.base.flags &= CRYPTO_TFM_REQ_MAY_BACKLOG;
207 err = xts_xor_tweak_post(req, true);
208
209 if (!err && unlikely(req->cryptlen % XTS_BLOCK_SIZE)) {
210 err = xts_cts_final(req, crypto_skcipher_encrypt);
211 if (err == -EINPROGRESS || err == -EBUSY)
212 return;
213 }
214 }
215
216 skcipher_request_complete(req, err);
217}
218
219static void xts_decrypt_done(void *data, int err)
220{
221 struct skcipher_request *req = data;
222
223 if (!err) {
224 struct xts_request_ctx *rctx = skcipher_request_ctx(req);
225
226 rctx->subreq.base.flags &= CRYPTO_TFM_REQ_MAY_BACKLOG;
227 err = xts_xor_tweak_post(req, false);
228
229 if (!err && unlikely(req->cryptlen % XTS_BLOCK_SIZE)) {
230 err = xts_cts_final(req, crypto_skcipher_decrypt);
231 if (err == -EINPROGRESS || err == -EBUSY)
232 return;
233 }
234 }
235
236 skcipher_request_complete(req, err);
237}
238
239static int xts_init_crypt(struct skcipher_request *req,
240 crypto_completion_t compl)
241{
242 const struct xts_tfm_ctx *ctx =
243 crypto_skcipher_ctx(crypto_skcipher_reqtfm(req));
244 struct xts_request_ctx *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 xts_encrypt(struct skcipher_request *req)
262{
263 struct xts_request_ctx *rctx = skcipher_request_ctx(req);
264 struct skcipher_request *subreq = &rctx->subreq;
265 int err;
266
267 err = xts_init_crypt(req, xts_encrypt_done) ?:
268 xts_xor_tweak_pre(req, true) ?:
269 crypto_skcipher_encrypt(subreq) ?:
270 xts_xor_tweak_post(req, true);
271
272 if (err || likely((req->cryptlen % XTS_BLOCK_SIZE) == 0))
273 return err;
274
275 return xts_cts_final(req, crypto_skcipher_encrypt);
276}
277
278static int xts_decrypt(struct skcipher_request *req)
279{
280 struct xts_request_ctx *rctx = skcipher_request_ctx(req);
281 struct skcipher_request *subreq = &rctx->subreq;
282 int err;
283
284 err = xts_init_crypt(req, xts_decrypt_done) ?:
285 xts_xor_tweak_pre(req, false) ?:
286 crypto_skcipher_decrypt(subreq) ?:
287 xts_xor_tweak_post(req, false);
288
289 if (err || likely((req->cryptlen % XTS_BLOCK_SIZE) == 0))
290 return err;
291
292 return xts_cts_final(req, crypto_skcipher_decrypt);
293}
294
295static int xts_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 xts_tfm_ctx *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_spawn_cipher(&ictx->tweak_spawn);
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 xts_request_ctx));
319
320 return 0;
321}
322
323static void xts_exit_tfm(struct crypto_skcipher *tfm)
324{
325 struct xts_tfm_ctx *ctx = crypto_skcipher_ctx(tfm);
326
327 crypto_free_skcipher(ctx->child);
328 crypto_free_cipher(ctx->tweak);
329}
330
331static void xts_free_instance(struct skcipher_instance *inst)
332{
333 struct xts_instance_ctx *ictx = skcipher_instance_ctx(inst);
334
335 crypto_drop_skcipher(&ictx->spawn);
336 crypto_drop_cipher(&ictx->tweak_spawn);
337 kfree(inst);
338}
339
340static int xts_create(struct crypto_template *tmpl, struct rtattr **tb)
341{
342 struct skcipher_alg_common *alg;
343 char name[CRYPTO_MAX_ALG_NAME];
344 struct skcipher_instance *inst;
345 struct xts_instance_ctx *ctx;
346 const char *cipher_name;
347 u32 mask;
348 int err;
349
350 err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SKCIPHER, &mask);
351 if (err)
352 return err;
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 err = crypto_grab_skcipher(&ctx->spawn, skcipher_crypto_instance(inst),
365 cipher_name, 0, mask);
366 if (err == -ENOENT) {
367 err = -ENAMETOOLONG;
368 if (snprintf(name, CRYPTO_MAX_ALG_NAME, "ecb(%s)",
369 cipher_name) >= CRYPTO_MAX_ALG_NAME)
370 goto err_free_inst;
371
372 err = crypto_grab_skcipher(&ctx->spawn,
373 skcipher_crypto_instance(inst),
374 name, 0, mask);
375 }
376
377 if (err)
378 goto err_free_inst;
379
380 alg = crypto_spawn_skcipher_alg_common(&ctx->spawn);
381
382 err = -EINVAL;
383 if (alg->base.cra_blocksize != XTS_BLOCK_SIZE)
384 goto err_free_inst;
385
386 if (alg->ivsize)
387 goto err_free_inst;
388
389 err = crypto_inst_setname(skcipher_crypto_instance(inst), "xts",
390 &alg->base);
391 if (err)
392 goto err_free_inst;
393
394 err = -EINVAL;
395 cipher_name = alg->base.cra_name;
396
397 /* Alas we screwed up the naming so we have to mangle the
398 * cipher name.
399 */
400 if (!strncmp(cipher_name, "ecb(", 4)) {
401 int len;
402
403 len = strscpy(name, cipher_name + 4, sizeof(name));
404 if (len < 2)
405 goto err_free_inst;
406
407 if (name[len - 1] != ')')
408 goto err_free_inst;
409
410 name[len - 1] = 0;
411
412 if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
413 "xts(%s)", name) >= CRYPTO_MAX_ALG_NAME) {
414 err = -ENAMETOOLONG;
415 goto err_free_inst;
416 }
417 } else
418 goto err_free_inst;
419
420 err = crypto_grab_cipher(&ctx->tweak_spawn,
421 skcipher_crypto_instance(inst), name, 0, mask);
422 if (err)
423 goto err_free_inst;
424
425 inst->alg.base.cra_priority = alg->base.cra_priority;
426 inst->alg.base.cra_blocksize = XTS_BLOCK_SIZE;
427 inst->alg.base.cra_alignmask = alg->base.cra_alignmask |
428 (__alignof__(u64) - 1);
429
430 inst->alg.ivsize = XTS_BLOCK_SIZE;
431 inst->alg.min_keysize = alg->min_keysize * 2;
432 inst->alg.max_keysize = alg->max_keysize * 2;
433
434 inst->alg.base.cra_ctxsize = sizeof(struct xts_tfm_ctx);
435
436 inst->alg.init = xts_init_tfm;
437 inst->alg.exit = xts_exit_tfm;
438
439 inst->alg.setkey = xts_setkey;
440 inst->alg.encrypt = xts_encrypt;
441 inst->alg.decrypt = xts_decrypt;
442
443 inst->free = xts_free_instance;
444
445 err = skcipher_register_instance(tmpl, inst);
446 if (err) {
447err_free_inst:
448 xts_free_instance(inst);
449 }
450 return err;
451}
452
453static struct crypto_template xts_tmpl = {
454 .name = "xts",
455 .create = xts_create,
456 .module = THIS_MODULE,
457};
458
459static int __init xts_module_init(void)
460{
461 return crypto_register_template(&xts_tmpl);
462}
463
464static void __exit xts_module_exit(void)
465{
466 crypto_unregister_template(&xts_tmpl);
467}
468
469subsys_initcall(xts_module_init);
470module_exit(xts_module_exit);
471
472MODULE_LICENSE("GPL");
473MODULE_DESCRIPTION("XTS block cipher mode");
474MODULE_ALIAS_CRYPTO("xts");
475MODULE_IMPORT_NS(CRYPTO_INTERNAL);
476MODULE_SOFTDEP("pre: ecb");
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 u32 *flags = &parent->crt_flags;
39 int err;
40
41 /* key consists of keys of equal size concatenated, therefore
42 * the length must be even */
43 if (keylen % 2) {
44 /* tell the user why there was an error */
45 *flags |= CRYPTO_TFM_RES_BAD_KEY_LEN;
46 return -EINVAL;
47 }
48
49 /* we need two cipher instances: one to compute the initial 'tweak'
50 * by encrypting the IV (usually the 'plain' iv) and the other
51 * one to encrypt and decrypt the data */
52
53 /* tweak cipher, uses Key2 i.e. the second half of *key */
54 crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
55 crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &
56 CRYPTO_TFM_REQ_MASK);
57 err = crypto_cipher_setkey(child, key + keylen/2, keylen/2);
58 if (err)
59 return err;
60
61 crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &
62 CRYPTO_TFM_RES_MASK);
63
64 child = ctx->child;
65
66 /* data cipher, uses Key1 i.e. the first half of *key */
67 crypto_cipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
68 crypto_cipher_set_flags(child, crypto_tfm_get_flags(parent) &
69 CRYPTO_TFM_REQ_MASK);
70 err = crypto_cipher_setkey(child, key, keylen/2);
71 if (err)
72 return err;
73
74 crypto_tfm_set_flags(parent, crypto_cipher_get_flags(child) &
75 CRYPTO_TFM_RES_MASK);
76
77 return 0;
78}
79
80struct sinfo {
81 be128 *t;
82 struct crypto_tfm *tfm;
83 void (*fn)(struct crypto_tfm *, u8 *, const u8 *);
84};
85
86static inline void xts_round(struct sinfo *s, void *dst, const void *src)
87{
88 be128_xor(dst, s->t, src); /* PP <- T xor P */
89 s->fn(s->tfm, dst, dst); /* CC <- E(Key1,PP) */
90 be128_xor(dst, dst, s->t); /* C <- T xor CC */
91}
92
93static int crypt(struct blkcipher_desc *d,
94 struct blkcipher_walk *w, struct priv *ctx,
95 void (*tw)(struct crypto_tfm *, u8 *, const u8 *),
96 void (*fn)(struct crypto_tfm *, u8 *, const u8 *))
97{
98 int err;
99 unsigned int avail;
100 const int bs = XTS_BLOCK_SIZE;
101 struct sinfo s = {
102 .tfm = crypto_cipher_tfm(ctx->child),
103 .fn = fn
104 };
105 u8 *wsrc;
106 u8 *wdst;
107
108 err = blkcipher_walk_virt(d, w);
109 if (!w->nbytes)
110 return err;
111
112 s.t = (be128 *)w->iv;
113 avail = w->nbytes;
114
115 wsrc = w->src.virt.addr;
116 wdst = w->dst.virt.addr;
117
118 /* calculate first value of T */
119 tw(crypto_cipher_tfm(ctx->tweak), w->iv, w->iv);
120
121 goto first;
122
123 for (;;) {
124 do {
125 gf128mul_x_ble(s.t, s.t);
126
127first:
128 xts_round(&s, wdst, wsrc);
129
130 wsrc += bs;
131 wdst += bs;
132 } while ((avail -= bs) >= bs);
133
134 err = blkcipher_walk_done(d, w, avail);
135 if (!w->nbytes)
136 break;
137
138 avail = w->nbytes;
139
140 wsrc = w->src.virt.addr;
141 wdst = w->dst.virt.addr;
142 }
143
144 return err;
145}
146
147static int encrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
148 struct scatterlist *src, unsigned int nbytes)
149{
150 struct priv *ctx = crypto_blkcipher_ctx(desc->tfm);
151 struct blkcipher_walk w;
152
153 blkcipher_walk_init(&w, dst, src, nbytes);
154 return crypt(desc, &w, ctx, crypto_cipher_alg(ctx->tweak)->cia_encrypt,
155 crypto_cipher_alg(ctx->child)->cia_encrypt);
156}
157
158static int decrypt(struct blkcipher_desc *desc, struct scatterlist *dst,
159 struct scatterlist *src, unsigned int nbytes)
160{
161 struct priv *ctx = crypto_blkcipher_ctx(desc->tfm);
162 struct blkcipher_walk w;
163
164 blkcipher_walk_init(&w, dst, src, nbytes);
165 return crypt(desc, &w, ctx, crypto_cipher_alg(ctx->tweak)->cia_encrypt,
166 crypto_cipher_alg(ctx->child)->cia_decrypt);
167}
168
169int xts_crypt(struct blkcipher_desc *desc, struct scatterlist *sdst,
170 struct scatterlist *ssrc, unsigned int nbytes,
171 struct xts_crypt_req *req)
172{
173 const unsigned int bsize = XTS_BLOCK_SIZE;
174 const unsigned int max_blks = req->tbuflen / bsize;
175 struct blkcipher_walk walk;
176 unsigned int nblocks;
177 be128 *src, *dst, *t;
178 be128 *t_buf = req->tbuf;
179 int err, i;
180
181 BUG_ON(max_blks < 1);
182
183 blkcipher_walk_init(&walk, sdst, ssrc, nbytes);
184
185 err = blkcipher_walk_virt(desc, &walk);
186 nbytes = walk.nbytes;
187 if (!nbytes)
188 return err;
189
190 nblocks = min(nbytes / bsize, max_blks);
191 src = (be128 *)walk.src.virt.addr;
192 dst = (be128 *)walk.dst.virt.addr;
193
194 /* calculate first value of T */
195 req->tweak_fn(req->tweak_ctx, (u8 *)&t_buf[0], walk.iv);
196
197 i = 0;
198 goto first;
199
200 for (;;) {
201 do {
202 for (i = 0; i < nblocks; i++) {
203 gf128mul_x_ble(&t_buf[i], t);
204first:
205 t = &t_buf[i];
206
207 /* PP <- T xor P */
208 be128_xor(dst + i, t, src + i);
209 }
210
211 /* CC <- E(Key2,PP) */
212 req->crypt_fn(req->crypt_ctx, (u8 *)dst,
213 nblocks * bsize);
214
215 /* C <- T xor CC */
216 for (i = 0; i < nblocks; i++)
217 be128_xor(dst + i, dst + i, &t_buf[i]);
218
219 src += nblocks;
220 dst += nblocks;
221 nbytes -= nblocks * bsize;
222 nblocks = min(nbytes / bsize, max_blks);
223 } while (nblocks > 0);
224
225 *(be128 *)walk.iv = *t;
226
227 err = blkcipher_walk_done(desc, &walk, nbytes);
228 nbytes = walk.nbytes;
229 if (!nbytes)
230 break;
231
232 nblocks = min(nbytes / bsize, max_blks);
233 src = (be128 *)walk.src.virt.addr;
234 dst = (be128 *)walk.dst.virt.addr;
235 }
236
237 return err;
238}
239EXPORT_SYMBOL_GPL(xts_crypt);
240
241static int init_tfm(struct crypto_tfm *tfm)
242{
243 struct crypto_cipher *cipher;
244 struct crypto_instance *inst = (void *)tfm->__crt_alg;
245 struct crypto_spawn *spawn = crypto_instance_ctx(inst);
246 struct priv *ctx = crypto_tfm_ctx(tfm);
247 u32 *flags = &tfm->crt_flags;
248
249 cipher = crypto_spawn_cipher(spawn);
250 if (IS_ERR(cipher))
251 return PTR_ERR(cipher);
252
253 if (crypto_cipher_blocksize(cipher) != XTS_BLOCK_SIZE) {
254 *flags |= CRYPTO_TFM_RES_BAD_BLOCK_LEN;
255 crypto_free_cipher(cipher);
256 return -EINVAL;
257 }
258
259 ctx->child = cipher;
260
261 cipher = crypto_spawn_cipher(spawn);
262 if (IS_ERR(cipher)) {
263 crypto_free_cipher(ctx->child);
264 return PTR_ERR(cipher);
265 }
266
267 /* this check isn't really needed, leave it here just in case */
268 if (crypto_cipher_blocksize(cipher) != XTS_BLOCK_SIZE) {
269 crypto_free_cipher(cipher);
270 crypto_free_cipher(ctx->child);
271 *flags |= CRYPTO_TFM_RES_BAD_BLOCK_LEN;
272 return -EINVAL;
273 }
274
275 ctx->tweak = cipher;
276
277 return 0;
278}
279
280static void exit_tfm(struct crypto_tfm *tfm)
281{
282 struct priv *ctx = crypto_tfm_ctx(tfm);
283 crypto_free_cipher(ctx->child);
284 crypto_free_cipher(ctx->tweak);
285}
286
287static struct crypto_instance *alloc(struct rtattr **tb)
288{
289 struct crypto_instance *inst;
290 struct crypto_alg *alg;
291 int err;
292
293 err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_BLKCIPHER);
294 if (err)
295 return ERR_PTR(err);
296
297 alg = crypto_get_attr_alg(tb, CRYPTO_ALG_TYPE_CIPHER,
298 CRYPTO_ALG_TYPE_MASK);
299 if (IS_ERR(alg))
300 return ERR_CAST(alg);
301
302 inst = crypto_alloc_instance("xts", alg);
303 if (IS_ERR(inst))
304 goto out_put_alg;
305
306 inst->alg.cra_flags = CRYPTO_ALG_TYPE_BLKCIPHER;
307 inst->alg.cra_priority = alg->cra_priority;
308 inst->alg.cra_blocksize = alg->cra_blocksize;
309
310 if (alg->cra_alignmask < 7)
311 inst->alg.cra_alignmask = 7;
312 else
313 inst->alg.cra_alignmask = alg->cra_alignmask;
314
315 inst->alg.cra_type = &crypto_blkcipher_type;
316
317 inst->alg.cra_blkcipher.ivsize = alg->cra_blocksize;
318 inst->alg.cra_blkcipher.min_keysize =
319 2 * alg->cra_cipher.cia_min_keysize;
320 inst->alg.cra_blkcipher.max_keysize =
321 2 * alg->cra_cipher.cia_max_keysize;
322
323 inst->alg.cra_ctxsize = sizeof(struct priv);
324
325 inst->alg.cra_init = init_tfm;
326 inst->alg.cra_exit = exit_tfm;
327
328 inst->alg.cra_blkcipher.setkey = setkey;
329 inst->alg.cra_blkcipher.encrypt = encrypt;
330 inst->alg.cra_blkcipher.decrypt = decrypt;
331
332out_put_alg:
333 crypto_mod_put(alg);
334 return inst;
335}
336
337static void free(struct crypto_instance *inst)
338{
339 crypto_drop_spawn(crypto_instance_ctx(inst));
340 kfree(inst);
341}
342
343static struct crypto_template crypto_tmpl = {
344 .name = "xts",
345 .alloc = alloc,
346 .free = free,
347 .module = THIS_MODULE,
348};
349
350static int __init crypto_module_init(void)
351{
352 return crypto_register_template(&crypto_tmpl);
353}
354
355static void __exit crypto_module_exit(void)
356{
357 crypto_unregister_template(&crypto_tmpl);
358}
359
360module_init(crypto_module_init);
361module_exit(crypto_module_exit);
362
363MODULE_LICENSE("GPL");
364MODULE_DESCRIPTION("XTS block cipher mode");