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Rik Snelf19f5112007-09-19 20:23:13 +08001/* 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 *
Corentin LABBEddbc7362016-08-10 11:29:33 +02008 * Based on ecb.c
Rik Snelf19f5112007-09-19 20:23:13 +08009 * 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
Jussi Kivilinnace004552011-11-09 11:56:06 +080024#include <crypto/xts.h>
Rik Snelf19f5112007-09-19 20:23:13 +080025#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;
Rik Snelf19f5112007-09-19 20:23:13 +080038 int err;
39
Stephan Mueller28856a92016-02-09 15:37:47 +010040 err = xts_check_key(parent, key, keylen);
41 if (err)
42 return err;
Rik Snelf19f5112007-09-19 20:23:13 +080043
Lucas De Marchi25985ed2011-03-30 22:57:33 -030044 /* we need two cipher instances: one to compute the initial 'tweak'
Rik Snelf19f5112007-09-19 20:23:13 +080045 * 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 {
Sebastian Siewior6212f2c2008-03-06 18:56:19 +080076 be128 *t;
Rik Snelf19f5112007-09-19 20:23:13 +080077 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{
Sebastian Siewior6212f2c2008-03-06 18:56:19 +080083 be128_xor(dst, s->t, src); /* PP <- T xor P */
Rik Snelf19f5112007-09-19 20:23:13 +080084 s->fn(s->tfm, dst, dst); /* CC <- E(Key1,PP) */
Sebastian Siewior6212f2c2008-03-06 18:56:19 +080085 be128_xor(dst, dst, s->t); /* C <- T xor CC */
Rik Snelf19f5112007-09-19 20:23:13 +080086}
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;
Jussi Kivilinnaf9d26912011-10-18 13:33:07 +030095 const int bs = XTS_BLOCK_SIZE;
Rik Snelf19f5112007-09-19 20:23:13 +080096 struct sinfo s = {
97 .tfm = crypto_cipher_tfm(ctx->child),
98 .fn = fn
99 };
Rik Snelf19f5112007-09-19 20:23:13 +0800100 u8 *wsrc;
101 u8 *wdst;
102
103 err = blkcipher_walk_virt(d, w);
104 if (!w->nbytes)
105 return err;
106
Sebastian Siewior6212f2c2008-03-06 18:56:19 +0800107 s.t = (be128 *)w->iv;
Rik Snelf19f5112007-09-19 20:23:13 +0800108 avail = w->nbytes;
109
110 wsrc = w->src.virt.addr;
111 wdst = w->dst.virt.addr;
112
113 /* calculate first value of T */
Sebastian Siewior6212f2c2008-03-06 18:56:19 +0800114 tw(crypto_cipher_tfm(ctx->tweak), w->iv, w->iv);
Rik Snelf19f5112007-09-19 20:23:13 +0800115
116 goto first;
117
118 for (;;) {
119 do {
Sebastian Siewior6212f2c2008-03-06 18:56:19 +0800120 gf128mul_x_ble(s.t, s.t);
Rik Snelf19f5112007-09-19 20:23:13 +0800121
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
Jussi Kivilinnace004552011-11-09 11:56:06 +0800164int 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
Rik Snelf19f5112007-09-19 20:23:13 +0800236static 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
Jussi Kivilinnaf9d26912011-10-18 13:33:07 +0300248 if (crypto_cipher_blocksize(cipher) != XTS_BLOCK_SIZE) {
Rik Snelf19f5112007-09-19 20:23:13 +0800249 *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 */
Jussi Kivilinnaf9d26912011-10-18 13:33:07 +0300263 if (crypto_cipher_blocksize(cipher) != XTS_BLOCK_SIZE) {
Rik Snelf19f5112007-09-19 20:23:13 +0800264 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))
Julia Lawall8db05072010-05-26 10:36:51 +1000295 return ERR_CAST(alg);
Rik Snelf19f5112007-09-19 20:23:13 +0800296
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
Linus Torvalds414eae12020-05-09 15:58:04 -0700332static void free_inst(struct crypto_instance *inst)
Rik Snelf19f5112007-09-19 20:23:13 +0800333{
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,
Linus Torvalds414eae12020-05-09 15:58:04 -0700341 .free = free_inst,
Rik Snelf19f5112007-09-19 20:23:13 +0800342 .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");
Kees Cook4943ba12014-11-24 16:32:38 -0800360MODULE_ALIAS_CRYPTO("xts");