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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");
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 on 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/internal/skcipher.h>
17#include <crypto/scatterwalk.h>
18#include <linux/err.h>
19#include <linux/init.h>
20#include <linux/kernel.h>
21#include <linux/module.h>
22#include <linux/scatterlist.h>
23#include <linux/slab.h>
24
25#include <crypto/xts.h>
26#include <crypto/b128ops.h>
27#include <crypto/gf128mul.h>
28
29#define XTS_BUFFER_SIZE 128u
30
31struct priv {
32 struct crypto_skcipher *child;
33 struct crypto_cipher *tweak;
34};
35
36struct xts_instance_ctx {
37 struct crypto_skcipher_spawn spawn;
38 char name[CRYPTO_MAX_ALG_NAME];
39};
40
41struct rctx {
42 be128 buf[XTS_BUFFER_SIZE / sizeof(be128)];
43
44 be128 t;
45
46 be128 *ext;
47
48 struct scatterlist srcbuf[2];
49 struct scatterlist dstbuf[2];
50 struct scatterlist *src;
51 struct scatterlist *dst;
52
53 unsigned int left;
54
55 struct skcipher_request subreq;
56};
57
58static int setkey(struct crypto_skcipher *parent, const u8 *key,
59 unsigned int keylen)
60{
61 struct priv *ctx = crypto_skcipher_ctx(parent);
62 struct crypto_skcipher *child;
63 struct crypto_cipher *tweak;
64 int err;
65
66 err = xts_verify_key(parent, key, keylen);
67 if (err)
68 return err;
69
70 keylen /= 2;
71
72 /* we need two cipher instances: one to compute the initial 'tweak'
73 * by encrypting the IV (usually the 'plain' iv) and the other
74 * one to encrypt and decrypt the data */
75
76 /* tweak cipher, uses Key2 i.e. the second half of *key */
77 tweak = ctx->tweak;
78 crypto_cipher_clear_flags(tweak, CRYPTO_TFM_REQ_MASK);
79 crypto_cipher_set_flags(tweak, crypto_skcipher_get_flags(parent) &
80 CRYPTO_TFM_REQ_MASK);
81 err = crypto_cipher_setkey(tweak, key + keylen, keylen);
82 crypto_skcipher_set_flags(parent, crypto_cipher_get_flags(tweak) &
83 CRYPTO_TFM_RES_MASK);
84 if (err)
85 return err;
86
87 /* data cipher, uses Key1 i.e. the first half of *key */
88 child = ctx->child;
89 crypto_skcipher_clear_flags(child, CRYPTO_TFM_REQ_MASK);
90 crypto_skcipher_set_flags(child, crypto_skcipher_get_flags(parent) &
91 CRYPTO_TFM_REQ_MASK);
92 err = crypto_skcipher_setkey(child, key, keylen);
93 crypto_skcipher_set_flags(parent, crypto_skcipher_get_flags(child) &
94 CRYPTO_TFM_RES_MASK);
95
96 return err;
97}
98
99static int post_crypt(struct skcipher_request *req)
100{
101 struct rctx *rctx = skcipher_request_ctx(req);
102 be128 *buf = rctx->ext ?: rctx->buf;
103 struct skcipher_request *subreq;
104 const int bs = XTS_BLOCK_SIZE;
105 struct skcipher_walk w;
106 struct scatterlist *sg;
107 unsigned offset;
108 int err;
109
110 subreq = &rctx->subreq;
111 err = skcipher_walk_virt(&w, subreq, false);
112
113 while (w.nbytes) {
114 unsigned int avail = w.nbytes;
115 be128 *wdst;
116
117 wdst = w.dst.virt.addr;
118
119 do {
120 be128_xor(wdst, buf++, wdst);
121 wdst++;
122 } while ((avail -= bs) >= bs);
123
124 err = skcipher_walk_done(&w, avail);
125 }
126
127 rctx->left -= subreq->cryptlen;
128
129 if (err || !rctx->left)
130 goto out;
131
132 rctx->dst = rctx->dstbuf;
133
134 scatterwalk_done(&w.out, 0, 1);
135 sg = w.out.sg;
136 offset = w.out.offset;
137
138 if (rctx->dst != sg) {
139 rctx->dst[0] = *sg;
140 sg_unmark_end(rctx->dst);
141 scatterwalk_crypto_chain(rctx->dst, sg_next(sg), 0, 2);
142 }
143 rctx->dst[0].length -= offset - sg->offset;
144 rctx->dst[0].offset = offset;
145
146out:
147 return err;
148}
149
150static int pre_crypt(struct skcipher_request *req)
151{
152 struct rctx *rctx = skcipher_request_ctx(req);
153 be128 *buf = rctx->ext ?: rctx->buf;
154 struct skcipher_request *subreq;
155 const int bs = XTS_BLOCK_SIZE;
156 struct skcipher_walk w;
157 struct scatterlist *sg;
158 unsigned cryptlen;
159 unsigned offset;
160 bool more;
161 int err;
162
163 subreq = &rctx->subreq;
164 cryptlen = subreq->cryptlen;
165
166 more = rctx->left > cryptlen;
167 if (!more)
168 cryptlen = rctx->left;
169
170 skcipher_request_set_crypt(subreq, rctx->src, rctx->dst,
171 cryptlen, NULL);
172
173 err = skcipher_walk_virt(&w, subreq, false);
174
175 while (w.nbytes) {
176 unsigned int avail = w.nbytes;
177 be128 *wsrc;
178 be128 *wdst;
179
180 wsrc = w.src.virt.addr;
181 wdst = w.dst.virt.addr;
182
183 do {
184 *buf++ = rctx->t;
185 be128_xor(wdst++, &rctx->t, wsrc++);
186 gf128mul_x_ble(&rctx->t, &rctx->t);
187 } while ((avail -= bs) >= bs);
188
189 err = skcipher_walk_done(&w, avail);
190 }
191
192 skcipher_request_set_crypt(subreq, rctx->dst, rctx->dst,
193 cryptlen, NULL);
194
195 if (err || !more)
196 goto out;
197
198 rctx->src = rctx->srcbuf;
199
200 scatterwalk_done(&w.in, 0, 1);
201 sg = w.in.sg;
202 offset = w.in.offset;
203
204 if (rctx->src != sg) {
205 rctx->src[0] = *sg;
206 sg_unmark_end(rctx->src);
207 scatterwalk_crypto_chain(rctx->src, sg_next(sg), 0, 2);
208 }
209 rctx->src[0].length -= offset - sg->offset;
210 rctx->src[0].offset = offset;
211
212out:
213 return err;
214}
215
216static int init_crypt(struct skcipher_request *req, crypto_completion_t done)
217{
218 struct priv *ctx = crypto_skcipher_ctx(crypto_skcipher_reqtfm(req));
219 struct rctx *rctx = skcipher_request_ctx(req);
220 struct skcipher_request *subreq;
221 gfp_t gfp;
222
223 subreq = &rctx->subreq;
224 skcipher_request_set_tfm(subreq, ctx->child);
225 skcipher_request_set_callback(subreq, req->base.flags, done, req);
226
227 gfp = req->base.flags & CRYPTO_TFM_REQ_MAY_SLEEP ? GFP_KERNEL :
228 GFP_ATOMIC;
229 rctx->ext = NULL;
230
231 subreq->cryptlen = XTS_BUFFER_SIZE;
232 if (req->cryptlen > XTS_BUFFER_SIZE) {
233 unsigned int n = min(req->cryptlen, (unsigned int)PAGE_SIZE);
234
235 rctx->ext = kmalloc(n, gfp);
236 if (rctx->ext)
237 subreq->cryptlen = n;
238 }
239
240 rctx->src = req->src;
241 rctx->dst = req->dst;
242 rctx->left = req->cryptlen;
243
244 /* calculate first value of T */
245 crypto_cipher_encrypt_one(ctx->tweak, (u8 *)&rctx->t, req->iv);
246
247 return 0;
248}
249
250static void exit_crypt(struct skcipher_request *req)
251{
252 struct rctx *rctx = skcipher_request_ctx(req);
253
254 rctx->left = 0;
255
256 if (rctx->ext)
257 kzfree(rctx->ext);
258}
259
260static int do_encrypt(struct skcipher_request *req, int err)
261{
262 struct rctx *rctx = skcipher_request_ctx(req);
263 struct skcipher_request *subreq;
264
265 subreq = &rctx->subreq;
266
267 while (!err && rctx->left) {
268 err = pre_crypt(req) ?:
269 crypto_skcipher_encrypt(subreq) ?:
270 post_crypt(req);
271
272 if (err == -EINPROGRESS ||
273 (err == -EBUSY &&
274 req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG))
275 return err;
276 }
277
278 exit_crypt(req);
279 return err;
280}
281
282static void encrypt_done(struct crypto_async_request *areq, int err)
283{
284 struct skcipher_request *req = areq->data;
285 struct skcipher_request *subreq;
286 struct rctx *rctx;
287
288 rctx = skcipher_request_ctx(req);
289 subreq = &rctx->subreq;
290 subreq->base.flags &= CRYPTO_TFM_REQ_MAY_BACKLOG;
291
292 err = do_encrypt(req, err ?: post_crypt(req));
293 if (rctx->left)
294 return;
295
296 skcipher_request_complete(req, err);
297}
298
299static int encrypt(struct skcipher_request *req)
300{
301 return do_encrypt(req, init_crypt(req, encrypt_done));
302}
303
304static int do_decrypt(struct skcipher_request *req, int err)
305{
306 struct rctx *rctx = skcipher_request_ctx(req);
307 struct skcipher_request *subreq;
308
309 subreq = &rctx->subreq;
310
311 while (!err && rctx->left) {
312 err = pre_crypt(req) ?:
313 crypto_skcipher_decrypt(subreq) ?:
314 post_crypt(req);
315
316 if (err == -EINPROGRESS ||
317 (err == -EBUSY &&
318 req->base.flags & CRYPTO_TFM_REQ_MAY_BACKLOG))
319 return err;
320 }
321
322 exit_crypt(req);
323 return err;
324}
325
326static void decrypt_done(struct crypto_async_request *areq, int err)
327{
328 struct skcipher_request *req = areq->data;
329 struct skcipher_request *subreq;
330 struct rctx *rctx;
331
332 rctx = skcipher_request_ctx(req);
333 subreq = &rctx->subreq;
334 subreq->base.flags &= CRYPTO_TFM_REQ_MAY_BACKLOG;
335
336 err = do_decrypt(req, err ?: post_crypt(req));
337 if (rctx->left)
338 return;
339
340 skcipher_request_complete(req, err);
341}
342
343static int decrypt(struct skcipher_request *req)
344{
345 return do_decrypt(req, init_crypt(req, decrypt_done));
346}
347
348int xts_crypt(struct blkcipher_desc *desc, struct scatterlist *sdst,
349 struct scatterlist *ssrc, unsigned int nbytes,
350 struct xts_crypt_req *req)
351{
352 const unsigned int bsize = XTS_BLOCK_SIZE;
353 const unsigned int max_blks = req->tbuflen / bsize;
354 struct blkcipher_walk walk;
355 unsigned int nblocks;
356 be128 *src, *dst, *t;
357 be128 *t_buf = req->tbuf;
358 int err, i;
359
360 BUG_ON(max_blks < 1);
361
362 blkcipher_walk_init(&walk, sdst, ssrc, nbytes);
363
364 err = blkcipher_walk_virt(desc, &walk);
365 nbytes = walk.nbytes;
366 if (!nbytes)
367 return err;
368
369 nblocks = min(nbytes / bsize, max_blks);
370 src = (be128 *)walk.src.virt.addr;
371 dst = (be128 *)walk.dst.virt.addr;
372
373 /* calculate first value of T */
374 req->tweak_fn(req->tweak_ctx, (u8 *)&t_buf[0], walk.iv);
375
376 i = 0;
377 goto first;
378
379 for (;;) {
380 do {
381 for (i = 0; i < nblocks; i++) {
382 gf128mul_x_ble(&t_buf[i], t);
383first:
384 t = &t_buf[i];
385
386 /* PP <- T xor P */
387 be128_xor(dst + i, t, src + i);
388 }
389
390 /* CC <- E(Key2,PP) */
391 req->crypt_fn(req->crypt_ctx, (u8 *)dst,
392 nblocks * bsize);
393
394 /* C <- T xor CC */
395 for (i = 0; i < nblocks; i++)
396 be128_xor(dst + i, dst + i, &t_buf[i]);
397
398 src += nblocks;
399 dst += nblocks;
400 nbytes -= nblocks * bsize;
401 nblocks = min(nbytes / bsize, max_blks);
402 } while (nblocks > 0);
403
404 *(be128 *)walk.iv = *t;
405
406 err = blkcipher_walk_done(desc, &walk, nbytes);
407 nbytes = walk.nbytes;
408 if (!nbytes)
409 break;
410
411 nblocks = min(nbytes / bsize, max_blks);
412 src = (be128 *)walk.src.virt.addr;
413 dst = (be128 *)walk.dst.virt.addr;
414 }
415
416 return err;
417}
418EXPORT_SYMBOL_GPL(xts_crypt);
419
420static int init_tfm(struct crypto_skcipher *tfm)
421{
422 struct skcipher_instance *inst = skcipher_alg_instance(tfm);
423 struct xts_instance_ctx *ictx = skcipher_instance_ctx(inst);
424 struct priv *ctx = crypto_skcipher_ctx(tfm);
425 struct crypto_skcipher *child;
426 struct crypto_cipher *tweak;
427
428 child = crypto_spawn_skcipher(&ictx->spawn);
429 if (IS_ERR(child))
430 return PTR_ERR(child);
431
432 ctx->child = child;
433
434 tweak = crypto_alloc_cipher(ictx->name, 0, 0);
435 if (IS_ERR(tweak)) {
436 crypto_free_skcipher(ctx->child);
437 return PTR_ERR(tweak);
438 }
439
440 ctx->tweak = tweak;
441
442 crypto_skcipher_set_reqsize(tfm, crypto_skcipher_reqsize(child) +
443 sizeof(struct rctx));
444
445 return 0;
446}
447
448static void exit_tfm(struct crypto_skcipher *tfm)
449{
450 struct priv *ctx = crypto_skcipher_ctx(tfm);
451
452 crypto_free_skcipher(ctx->child);
453 crypto_free_cipher(ctx->tweak);
454}
455
456static void free(struct skcipher_instance *inst)
457{
458 crypto_drop_skcipher(skcipher_instance_ctx(inst));
459 kfree(inst);
460}
461
462static int create(struct crypto_template *tmpl, struct rtattr **tb)
463{
464 struct skcipher_instance *inst;
465 struct crypto_attr_type *algt;
466 struct xts_instance_ctx *ctx;
467 struct skcipher_alg *alg;
468 const char *cipher_name;
469 u32 mask;
470 int err;
471
472 algt = crypto_get_attr_type(tb);
473 if (IS_ERR(algt))
474 return PTR_ERR(algt);
475
476 if ((algt->type ^ CRYPTO_ALG_TYPE_SKCIPHER) & algt->mask)
477 return -EINVAL;
478
479 cipher_name = crypto_attr_alg_name(tb[1]);
480 if (IS_ERR(cipher_name))
481 return PTR_ERR(cipher_name);
482
483 inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
484 if (!inst)
485 return -ENOMEM;
486
487 ctx = skcipher_instance_ctx(inst);
488
489 crypto_set_skcipher_spawn(&ctx->spawn, skcipher_crypto_instance(inst));
490
491 mask = crypto_requires_off(algt->type, algt->mask,
492 CRYPTO_ALG_NEED_FALLBACK |
493 CRYPTO_ALG_ASYNC);
494
495 err = crypto_grab_skcipher(&ctx->spawn, cipher_name, 0, mask);
496 if (err == -ENOENT) {
497 err = -ENAMETOOLONG;
498 if (snprintf(ctx->name, CRYPTO_MAX_ALG_NAME, "ecb(%s)",
499 cipher_name) >= CRYPTO_MAX_ALG_NAME)
500 goto err_free_inst;
501
502 err = crypto_grab_skcipher(&ctx->spawn, ctx->name, 0, mask);
503 }
504
505 if (err)
506 goto err_free_inst;
507
508 alg = crypto_skcipher_spawn_alg(&ctx->spawn);
509
510 err = -EINVAL;
511 if (alg->base.cra_blocksize != XTS_BLOCK_SIZE)
512 goto err_drop_spawn;
513
514 if (crypto_skcipher_alg_ivsize(alg))
515 goto err_drop_spawn;
516
517 err = crypto_inst_setname(skcipher_crypto_instance(inst), "xts",
518 &alg->base);
519 if (err)
520 goto err_drop_spawn;
521
522 err = -EINVAL;
523 cipher_name = alg->base.cra_name;
524
525 /* Alas we screwed up the naming so we have to mangle the
526 * cipher name.
527 */
528 if (!strncmp(cipher_name, "ecb(", 4)) {
529 unsigned len;
530
531 len = strlcpy(ctx->name, cipher_name + 4, sizeof(ctx->name));
532 if (len < 2 || len >= sizeof(ctx->name))
533 goto err_drop_spawn;
534
535 if (ctx->name[len - 1] != ')')
536 goto err_drop_spawn;
537
538 ctx->name[len - 1] = 0;
539
540 if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
541 "xts(%s)", ctx->name) >= CRYPTO_MAX_ALG_NAME)
542 return -ENAMETOOLONG;
543 } else
544 goto err_drop_spawn;
545
546 inst->alg.base.cra_flags = alg->base.cra_flags & CRYPTO_ALG_ASYNC;
547 inst->alg.base.cra_priority = alg->base.cra_priority;
548 inst->alg.base.cra_blocksize = XTS_BLOCK_SIZE;
549 inst->alg.base.cra_alignmask = alg->base.cra_alignmask |
550 (__alignof__(u64) - 1);
551
552 inst->alg.ivsize = XTS_BLOCK_SIZE;
553 inst->alg.min_keysize = crypto_skcipher_alg_min_keysize(alg) * 2;
554 inst->alg.max_keysize = crypto_skcipher_alg_max_keysize(alg) * 2;
555
556 inst->alg.base.cra_ctxsize = sizeof(struct priv);
557
558 inst->alg.init = init_tfm;
559 inst->alg.exit = exit_tfm;
560
561 inst->alg.setkey = setkey;
562 inst->alg.encrypt = encrypt;
563 inst->alg.decrypt = decrypt;
564
565 inst->free = free;
566
567 err = skcipher_register_instance(tmpl, inst);
568 if (err)
569 goto err_drop_spawn;
570
571out:
572 return err;
573
574err_drop_spawn:
575 crypto_drop_skcipher(&ctx->spawn);
576err_free_inst:
577 kfree(inst);
578 goto out;
579}
580
581static struct crypto_template crypto_tmpl = {
582 .name = "xts",
583 .create = create,
584 .module = THIS_MODULE,
585};
586
587static int __init crypto_module_init(void)
588{
589 return crypto_register_template(&crypto_tmpl);
590}
591
592static void __exit crypto_module_exit(void)
593{
594 crypto_unregister_template(&crypto_tmpl);
595}
596
597module_init(crypto_module_init);
598module_exit(crypto_module_exit);
599
600MODULE_LICENSE("GPL");
601MODULE_DESCRIPTION("XTS block cipher mode");
602MODULE_ALIAS_CRYPTO("xts");