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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 le128 buf[XTS_BUFFER_SIZE / sizeof(le128)];
43
44 le128 t;
45
46 le128 *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
73
74
75
76
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
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 le128 *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 le128 *wdst;
116
117 wdst = w.dst.virt.addr;
118
119 do {
120 le128_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 le128 *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 le128 *wsrc;
178 le128 *wdst;
179
180 wsrc = w.src.virt.addr;
181 wdst = w.dst.virt.addr;
182
183 do {
184 *buf++ = rctx->t;
185 le128_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
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 || err == -EBUSY)
273 return err;
274 }
275
276 exit_crypt(req);
277 return err;
278}
279
280static void encrypt_done(struct crypto_async_request *areq, int err)
281{
282 struct skcipher_request *req = areq->data;
283 struct skcipher_request *subreq;
284 struct rctx *rctx;
285
286 rctx = skcipher_request_ctx(req);
287
288 if (err == -EINPROGRESS) {
289 if (rctx->left != req->cryptlen)
290 return;
291 goto out;
292 }
293
294 subreq = &rctx->subreq;
295 subreq->base.flags &= CRYPTO_TFM_REQ_MAY_BACKLOG;
296
297 err = do_encrypt(req, err ?: post_crypt(req));
298 if (rctx->left)
299 return;
300
301out:
302 skcipher_request_complete(req, err);
303}
304
305static int encrypt(struct skcipher_request *req)
306{
307 return do_encrypt(req, init_crypt(req, encrypt_done));
308}
309
310static int do_decrypt(struct skcipher_request *req, int err)
311{
312 struct rctx *rctx = skcipher_request_ctx(req);
313 struct skcipher_request *subreq;
314
315 subreq = &rctx->subreq;
316
317 while (!err && rctx->left) {
318 err = pre_crypt(req) ?:
319 crypto_skcipher_decrypt(subreq) ?:
320 post_crypt(req);
321
322 if (err == -EINPROGRESS || err == -EBUSY)
323 return err;
324 }
325
326 exit_crypt(req);
327 return err;
328}
329
330static void decrypt_done(struct crypto_async_request *areq, int err)
331{
332 struct skcipher_request *req = areq->data;
333 struct skcipher_request *subreq;
334 struct rctx *rctx;
335
336 rctx = skcipher_request_ctx(req);
337
338 if (err == -EINPROGRESS) {
339 if (rctx->left != req->cryptlen)
340 return;
341 goto out;
342 }
343
344 subreq = &rctx->subreq;
345 subreq->base.flags &= CRYPTO_TFM_REQ_MAY_BACKLOG;
346
347 err = do_decrypt(req, err ?: post_crypt(req));
348 if (rctx->left)
349 return;
350
351out:
352 skcipher_request_complete(req, err);
353}
354
355static int decrypt(struct skcipher_request *req)
356{
357 return do_decrypt(req, init_crypt(req, decrypt_done));
358}
359
360static int init_tfm(struct crypto_skcipher *tfm)
361{
362 struct skcipher_instance *inst = skcipher_alg_instance(tfm);
363 struct xts_instance_ctx *ictx = skcipher_instance_ctx(inst);
364 struct priv *ctx = crypto_skcipher_ctx(tfm);
365 struct crypto_skcipher *child;
366 struct crypto_cipher *tweak;
367
368 child = crypto_spawn_skcipher(&ictx->spawn);
369 if (IS_ERR(child))
370 return PTR_ERR(child);
371
372 ctx->child = child;
373
374 tweak = crypto_alloc_cipher(ictx->name, 0, 0);
375 if (IS_ERR(tweak)) {
376 crypto_free_skcipher(ctx->child);
377 return PTR_ERR(tweak);
378 }
379
380 ctx->tweak = tweak;
381
382 crypto_skcipher_set_reqsize(tfm, crypto_skcipher_reqsize(child) +
383 sizeof(struct rctx));
384
385 return 0;
386}
387
388static void exit_tfm(struct crypto_skcipher *tfm)
389{
390 struct priv *ctx = crypto_skcipher_ctx(tfm);
391
392 crypto_free_skcipher(ctx->child);
393 crypto_free_cipher(ctx->tweak);
394}
395
396static void free(struct skcipher_instance *inst)
397{
398 crypto_drop_skcipher(skcipher_instance_ctx(inst));
399 kfree(inst);
400}
401
402static int create(struct crypto_template *tmpl, struct rtattr **tb)
403{
404 struct skcipher_instance *inst;
405 struct crypto_attr_type *algt;
406 struct xts_instance_ctx *ctx;
407 struct skcipher_alg *alg;
408 const char *cipher_name;
409 u32 mask;
410 int err;
411
412 algt = crypto_get_attr_type(tb);
413 if (IS_ERR(algt))
414 return PTR_ERR(algt);
415
416 if ((algt->type ^ CRYPTO_ALG_TYPE_SKCIPHER) & algt->mask)
417 return -EINVAL;
418
419 cipher_name = crypto_attr_alg_name(tb[1]);
420 if (IS_ERR(cipher_name))
421 return PTR_ERR(cipher_name);
422
423 inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
424 if (!inst)
425 return -ENOMEM;
426
427 ctx = skcipher_instance_ctx(inst);
428
429 crypto_set_skcipher_spawn(&ctx->spawn, skcipher_crypto_instance(inst));
430
431 mask = crypto_requires_off(algt->type, algt->mask,
432 CRYPTO_ALG_NEED_FALLBACK |
433 CRYPTO_ALG_ASYNC);
434
435 err = crypto_grab_skcipher(&ctx->spawn, cipher_name, 0, mask);
436 if (err == -ENOENT) {
437 err = -ENAMETOOLONG;
438 if (snprintf(ctx->name, CRYPTO_MAX_ALG_NAME, "ecb(%s)",
439 cipher_name) >= CRYPTO_MAX_ALG_NAME)
440 goto err_free_inst;
441
442 err = crypto_grab_skcipher(&ctx->spawn, ctx->name, 0, mask);
443 }
444
445 if (err)
446 goto err_free_inst;
447
448 alg = crypto_skcipher_spawn_alg(&ctx->spawn);
449
450 err = -EINVAL;
451 if (alg->base.cra_blocksize != XTS_BLOCK_SIZE)
452 goto err_drop_spawn;
453
454 if (crypto_skcipher_alg_ivsize(alg))
455 goto err_drop_spawn;
456
457 err = crypto_inst_setname(skcipher_crypto_instance(inst), "xts",
458 &alg->base);
459 if (err)
460 goto err_drop_spawn;
461
462 err = -EINVAL;
463 cipher_name = alg->base.cra_name;
464
465
466
467
468 if (!strncmp(cipher_name, "ecb(", 4)) {
469 unsigned len;
470
471 len = strlcpy(ctx->name, cipher_name + 4, sizeof(ctx->name));
472 if (len < 2 || len >= sizeof(ctx->name))
473 goto err_drop_spawn;
474
475 if (ctx->name[len - 1] != ')')
476 goto err_drop_spawn;
477
478 ctx->name[len - 1] = 0;
479
480 if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
481 "xts(%s)", ctx->name) >= CRYPTO_MAX_ALG_NAME) {
482 err = -ENAMETOOLONG;
483 goto err_drop_spawn;
484 }
485 } else
486 goto err_drop_spawn;
487
488 inst->alg.base.cra_flags = alg->base.cra_flags & CRYPTO_ALG_ASYNC;
489 inst->alg.base.cra_priority = alg->base.cra_priority;
490 inst->alg.base.cra_blocksize = XTS_BLOCK_SIZE;
491 inst->alg.base.cra_alignmask = alg->base.cra_alignmask |
492 (__alignof__(u64) - 1);
493
494 inst->alg.ivsize = XTS_BLOCK_SIZE;
495 inst->alg.min_keysize = crypto_skcipher_alg_min_keysize(alg) * 2;
496 inst->alg.max_keysize = crypto_skcipher_alg_max_keysize(alg) * 2;
497
498 inst->alg.base.cra_ctxsize = sizeof(struct priv);
499
500 inst->alg.init = init_tfm;
501 inst->alg.exit = exit_tfm;
502
503 inst->alg.setkey = setkey;
504 inst->alg.encrypt = encrypt;
505 inst->alg.decrypt = decrypt;
506
507 inst->free = free;
508
509 err = skcipher_register_instance(tmpl, inst);
510 if (err)
511 goto err_drop_spawn;
512
513out:
514 return err;
515
516err_drop_spawn:
517 crypto_drop_skcipher(&ctx->spawn);
518err_free_inst:
519 kfree(inst);
520 goto out;
521}
522
523static struct crypto_template crypto_tmpl = {
524 .name = "xts",
525 .create = create,
526 .module = THIS_MODULE,
527};
528
529static int __init crypto_module_init(void)
530{
531 return crypto_register_template(&crypto_tmpl);
532}
533
534static void __exit crypto_module_exit(void)
535{
536 crypto_unregister_template(&crypto_tmpl);
537}
538
539module_init(crypto_module_init);
540module_exit(crypto_module_exit);
541
542MODULE_LICENSE("GPL");
543MODULE_DESCRIPTION("XTS block cipher mode");
544MODULE_ALIAS_CRYPTO("xts");
545
