1 /*
2  * RSA padding templates.
3  *
4  * Copyright (c) 2015  Intel Corporation
5  *
6  * This program is free software; you can redistribute it and/or modify it
7  * under the terms of the GNU General Public License as published by the Free
8  * Software Foundation; either version 2 of the License, or (at your option)
9  * any later version.
10  */
11 
12 #include <crypto/algapi.h>
13 #include <crypto/akcipher.h>
14 #include <crypto/internal/akcipher.h>
15 #include <linux/err.h>
16 #include <linux/init.h>
17 #include <linux/kernel.h>
18 #include <linux/module.h>
19 #include <linux/random.h>
20 
21 /*
22  * Hash algorithm OIDs plus ASN.1 DER wrappings [RFC4880 sec 5.2.2].
23  */
24 static const u8 rsa_digest_info_md5[] = {
25 	0x30, 0x20, 0x30, 0x0c, 0x06, 0x08,
26 	0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d, 0x02, 0x05, /* OID */
27 	0x05, 0x00, 0x04, 0x10
28 };
29 
30 static const u8 rsa_digest_info_sha1[] = {
31 	0x30, 0x21, 0x30, 0x09, 0x06, 0x05,
32 	0x2b, 0x0e, 0x03, 0x02, 0x1a,
33 	0x05, 0x00, 0x04, 0x14
34 };
35 
36 static const u8 rsa_digest_info_rmd160[] = {
37 	0x30, 0x21, 0x30, 0x09, 0x06, 0x05,
38 	0x2b, 0x24, 0x03, 0x02, 0x01,
39 	0x05, 0x00, 0x04, 0x14
40 };
41 
42 static const u8 rsa_digest_info_sha224[] = {
43 	0x30, 0x2d, 0x30, 0x0d, 0x06, 0x09,
44 	0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x04,
45 	0x05, 0x00, 0x04, 0x1c
46 };
47 
48 static const u8 rsa_digest_info_sha256[] = {
49 	0x30, 0x31, 0x30, 0x0d, 0x06, 0x09,
50 	0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x01,
51 	0x05, 0x00, 0x04, 0x20
52 };
53 
54 static const u8 rsa_digest_info_sha384[] = {
55 	0x30, 0x41, 0x30, 0x0d, 0x06, 0x09,
56 	0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x02,
57 	0x05, 0x00, 0x04, 0x30
58 };
59 
60 static const u8 rsa_digest_info_sha512[] = {
61 	0x30, 0x51, 0x30, 0x0d, 0x06, 0x09,
62 	0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x03,
63 	0x05, 0x00, 0x04, 0x40
64 };
65 
66 static const struct rsa_asn1_template {
67 	const char	*name;
68 	const u8	*data;
69 	size_t		size;
70 } rsa_asn1_templates[] = {
71 #define _(X) { #X, rsa_digest_info_##X, sizeof(rsa_digest_info_##X) }
72 	_(md5),
73 	_(sha1),
74 	_(rmd160),
75 	_(sha256),
76 	_(sha384),
77 	_(sha512),
78 	_(sha224),
79 	{ NULL }
80 #undef _
81 };
82 
rsa_lookup_asn1(const char * name)83 static const struct rsa_asn1_template *rsa_lookup_asn1(const char *name)
84 {
85 	const struct rsa_asn1_template *p;
86 
87 	for (p = rsa_asn1_templates; p->name; p++)
88 		if (strcmp(name, p->name) == 0)
89 			return p;
90 	return NULL;
91 }
92 
93 struct pkcs1pad_ctx {
94 	struct crypto_akcipher *child;
95 	unsigned int key_size;
96 };
97 
98 struct pkcs1pad_inst_ctx {
99 	struct crypto_akcipher_spawn spawn;
100 	const struct rsa_asn1_template *digest_info;
101 };
102 
103 struct pkcs1pad_request {
104 	struct scatterlist in_sg[2], out_sg[1];
105 	uint8_t *in_buf, *out_buf;
106 	struct akcipher_request child_req;
107 };
108 
pkcs1pad_set_pub_key(struct crypto_akcipher * tfm,const void * key,unsigned int keylen)109 static int pkcs1pad_set_pub_key(struct crypto_akcipher *tfm, const void *key,
110 		unsigned int keylen)
111 {
112 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
113 	int err;
114 
115 	ctx->key_size = 0;
116 
117 	err = crypto_akcipher_set_pub_key(ctx->child, key, keylen);
118 	if (err)
119 		return err;
120 
121 	/* Find out new modulus size from rsa implementation */
122 	err = crypto_akcipher_maxsize(ctx->child);
123 	if (err > PAGE_SIZE)
124 		return -ENOTSUPP;
125 
126 	ctx->key_size = err;
127 	return 0;
128 }
129 
pkcs1pad_set_priv_key(struct crypto_akcipher * tfm,const void * key,unsigned int keylen)130 static int pkcs1pad_set_priv_key(struct crypto_akcipher *tfm, const void *key,
131 		unsigned int keylen)
132 {
133 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
134 	int err;
135 
136 	ctx->key_size = 0;
137 
138 	err = crypto_akcipher_set_priv_key(ctx->child, key, keylen);
139 	if (err)
140 		return err;
141 
142 	/* Find out new modulus size from rsa implementation */
143 	err = crypto_akcipher_maxsize(ctx->child);
144 	if (err > PAGE_SIZE)
145 		return -ENOTSUPP;
146 
147 	ctx->key_size = err;
148 	return 0;
149 }
150 
pkcs1pad_get_max_size(struct crypto_akcipher * tfm)151 static unsigned int pkcs1pad_get_max_size(struct crypto_akcipher *tfm)
152 {
153 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
154 
155 	/*
156 	 * The maximum destination buffer size for the encrypt/sign operations
157 	 * will be the same as for RSA, even though it's smaller for
158 	 * decrypt/verify.
159 	 */
160 
161 	return ctx->key_size;
162 }
163 
pkcs1pad_sg_set_buf(struct scatterlist * sg,void * buf,size_t len,struct scatterlist * next)164 static void pkcs1pad_sg_set_buf(struct scatterlist *sg, void *buf, size_t len,
165 		struct scatterlist *next)
166 {
167 	int nsegs = next ? 2 : 1;
168 
169 	sg_init_table(sg, nsegs);
170 	sg_set_buf(sg, buf, len);
171 
172 	if (next)
173 		sg_chain(sg, nsegs, next);
174 }
175 
pkcs1pad_encrypt_sign_complete(struct akcipher_request * req,int err)176 static int pkcs1pad_encrypt_sign_complete(struct akcipher_request *req, int err)
177 {
178 	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
179 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
180 	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
181 	unsigned int pad_len;
182 	unsigned int len;
183 	u8 *out_buf;
184 
185 	if (err)
186 		goto out;
187 
188 	len = req_ctx->child_req.dst_len;
189 	pad_len = ctx->key_size - len;
190 
191 	/* Four billion to one */
192 	if (likely(!pad_len))
193 		goto out;
194 
195 	out_buf = kzalloc(ctx->key_size, GFP_KERNEL);
196 	err = -ENOMEM;
197 	if (!out_buf)
198 		goto out;
199 
200 	sg_copy_to_buffer(req->dst, sg_nents_for_len(req->dst, len),
201 			  out_buf + pad_len, len);
202 	sg_copy_from_buffer(req->dst,
203 			    sg_nents_for_len(req->dst, ctx->key_size),
204 			    out_buf, ctx->key_size);
205 	kzfree(out_buf);
206 
207 out:
208 	req->dst_len = ctx->key_size;
209 
210 	kfree(req_ctx->in_buf);
211 
212 	return err;
213 }
214 
pkcs1pad_encrypt_sign_complete_cb(struct crypto_async_request * child_async_req,int err)215 static void pkcs1pad_encrypt_sign_complete_cb(
216 		struct crypto_async_request *child_async_req, int err)
217 {
218 	struct akcipher_request *req = child_async_req->data;
219 	struct crypto_async_request async_req;
220 
221 	if (err == -EINPROGRESS)
222 		return;
223 
224 	async_req.data = req->base.data;
225 	async_req.tfm = crypto_akcipher_tfm(crypto_akcipher_reqtfm(req));
226 	async_req.flags = child_async_req->flags;
227 	req->base.complete(&async_req,
228 			pkcs1pad_encrypt_sign_complete(req, err));
229 }
230 
pkcs1pad_encrypt(struct akcipher_request * req)231 static int pkcs1pad_encrypt(struct akcipher_request *req)
232 {
233 	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
234 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
235 	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
236 	int err;
237 	unsigned int i, ps_end;
238 
239 	if (!ctx->key_size)
240 		return -EINVAL;
241 
242 	if (req->src_len > ctx->key_size - 11)
243 		return -EOVERFLOW;
244 
245 	if (req->dst_len < ctx->key_size) {
246 		req->dst_len = ctx->key_size;
247 		return -EOVERFLOW;
248 	}
249 
250 	req_ctx->in_buf = kmalloc(ctx->key_size - 1 - req->src_len,
251 				  GFP_KERNEL);
252 	if (!req_ctx->in_buf)
253 		return -ENOMEM;
254 
255 	ps_end = ctx->key_size - req->src_len - 2;
256 	req_ctx->in_buf[0] = 0x02;
257 	for (i = 1; i < ps_end; i++)
258 		req_ctx->in_buf[i] = 1 + prandom_u32_max(255);
259 	req_ctx->in_buf[ps_end] = 0x00;
260 
261 	pkcs1pad_sg_set_buf(req_ctx->in_sg, req_ctx->in_buf,
262 			ctx->key_size - 1 - req->src_len, req->src);
263 
264 	req_ctx->out_buf = kmalloc(ctx->key_size, GFP_KERNEL);
265 	if (!req_ctx->out_buf) {
266 		kfree(req_ctx->in_buf);
267 		return -ENOMEM;
268 	}
269 
270 	pkcs1pad_sg_set_buf(req_ctx->out_sg, req_ctx->out_buf,
271 			ctx->key_size, NULL);
272 
273 	akcipher_request_set_tfm(&req_ctx->child_req, ctx->child);
274 	akcipher_request_set_callback(&req_ctx->child_req, req->base.flags,
275 			pkcs1pad_encrypt_sign_complete_cb, req);
276 
277 	/* Reuse output buffer */
278 	akcipher_request_set_crypt(&req_ctx->child_req, req_ctx->in_sg,
279 				   req->dst, ctx->key_size - 1, req->dst_len);
280 
281 	err = crypto_akcipher_encrypt(&req_ctx->child_req);
282 	if (err != -EINPROGRESS && err != -EBUSY)
283 		return pkcs1pad_encrypt_sign_complete(req, err);
284 
285 	return err;
286 }
287 
pkcs1pad_decrypt_complete(struct akcipher_request * req,int err)288 static int pkcs1pad_decrypt_complete(struct akcipher_request *req, int err)
289 {
290 	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
291 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
292 	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
293 	unsigned int dst_len;
294 	unsigned int pos;
295 	u8 *out_buf;
296 
297 	if (err)
298 		goto done;
299 
300 	err = -EINVAL;
301 	dst_len = req_ctx->child_req.dst_len;
302 	if (dst_len < ctx->key_size - 1)
303 		goto done;
304 
305 	out_buf = req_ctx->out_buf;
306 	if (dst_len == ctx->key_size) {
307 		if (out_buf[0] != 0x00)
308 			/* Decrypted value had no leading 0 byte */
309 			goto done;
310 
311 		dst_len--;
312 		out_buf++;
313 	}
314 
315 	if (out_buf[0] != 0x02)
316 		goto done;
317 
318 	for (pos = 1; pos < dst_len; pos++)
319 		if (out_buf[pos] == 0x00)
320 			break;
321 	if (pos < 9 || pos == dst_len)
322 		goto done;
323 	pos++;
324 
325 	err = 0;
326 
327 	if (req->dst_len < dst_len - pos)
328 		err = -EOVERFLOW;
329 	req->dst_len = dst_len - pos;
330 
331 	if (!err)
332 		sg_copy_from_buffer(req->dst,
333 				sg_nents_for_len(req->dst, req->dst_len),
334 				out_buf + pos, req->dst_len);
335 
336 done:
337 	kzfree(req_ctx->out_buf);
338 
339 	return err;
340 }
341 
pkcs1pad_decrypt_complete_cb(struct crypto_async_request * child_async_req,int err)342 static void pkcs1pad_decrypt_complete_cb(
343 		struct crypto_async_request *child_async_req, int err)
344 {
345 	struct akcipher_request *req = child_async_req->data;
346 	struct crypto_async_request async_req;
347 
348 	if (err == -EINPROGRESS)
349 		return;
350 
351 	async_req.data = req->base.data;
352 	async_req.tfm = crypto_akcipher_tfm(crypto_akcipher_reqtfm(req));
353 	async_req.flags = child_async_req->flags;
354 	req->base.complete(&async_req, pkcs1pad_decrypt_complete(req, err));
355 }
356 
pkcs1pad_decrypt(struct akcipher_request * req)357 static int pkcs1pad_decrypt(struct akcipher_request *req)
358 {
359 	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
360 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
361 	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
362 	int err;
363 
364 	if (!ctx->key_size || req->src_len != ctx->key_size)
365 		return -EINVAL;
366 
367 	req_ctx->out_buf = kmalloc(ctx->key_size, GFP_KERNEL);
368 	if (!req_ctx->out_buf)
369 		return -ENOMEM;
370 
371 	pkcs1pad_sg_set_buf(req_ctx->out_sg, req_ctx->out_buf,
372 			    ctx->key_size, NULL);
373 
374 	akcipher_request_set_tfm(&req_ctx->child_req, ctx->child);
375 	akcipher_request_set_callback(&req_ctx->child_req, req->base.flags,
376 			pkcs1pad_decrypt_complete_cb, req);
377 
378 	/* Reuse input buffer, output to a new buffer */
379 	akcipher_request_set_crypt(&req_ctx->child_req, req->src,
380 				   req_ctx->out_sg, req->src_len,
381 				   ctx->key_size);
382 
383 	err = crypto_akcipher_decrypt(&req_ctx->child_req);
384 	if (err != -EINPROGRESS && err != -EBUSY)
385 		return pkcs1pad_decrypt_complete(req, err);
386 
387 	return err;
388 }
389 
pkcs1pad_sign(struct akcipher_request * req)390 static int pkcs1pad_sign(struct akcipher_request *req)
391 {
392 	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
393 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
394 	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
395 	struct akcipher_instance *inst = akcipher_alg_instance(tfm);
396 	struct pkcs1pad_inst_ctx *ictx = akcipher_instance_ctx(inst);
397 	const struct rsa_asn1_template *digest_info = ictx->digest_info;
398 	int err;
399 	unsigned int ps_end, digest_size = 0;
400 
401 	if (!ctx->key_size)
402 		return -EINVAL;
403 
404 	digest_size = digest_info->size;
405 
406 	if (req->src_len + digest_size > ctx->key_size - 11)
407 		return -EOVERFLOW;
408 
409 	if (req->dst_len < ctx->key_size) {
410 		req->dst_len = ctx->key_size;
411 		return -EOVERFLOW;
412 	}
413 
414 	req_ctx->in_buf = kmalloc(ctx->key_size - 1 - req->src_len,
415 				  GFP_KERNEL);
416 	if (!req_ctx->in_buf)
417 		return -ENOMEM;
418 
419 	ps_end = ctx->key_size - digest_size - req->src_len - 2;
420 	req_ctx->in_buf[0] = 0x01;
421 	memset(req_ctx->in_buf + 1, 0xff, ps_end - 1);
422 	req_ctx->in_buf[ps_end] = 0x00;
423 
424 	memcpy(req_ctx->in_buf + ps_end + 1, digest_info->data,
425 	       digest_info->size);
426 
427 	pkcs1pad_sg_set_buf(req_ctx->in_sg, req_ctx->in_buf,
428 			ctx->key_size - 1 - req->src_len, req->src);
429 
430 	akcipher_request_set_tfm(&req_ctx->child_req, ctx->child);
431 	akcipher_request_set_callback(&req_ctx->child_req, req->base.flags,
432 			pkcs1pad_encrypt_sign_complete_cb, req);
433 
434 	/* Reuse output buffer */
435 	akcipher_request_set_crypt(&req_ctx->child_req, req_ctx->in_sg,
436 				   req->dst, ctx->key_size - 1, req->dst_len);
437 
438 	err = crypto_akcipher_sign(&req_ctx->child_req);
439 	if (err != -EINPROGRESS && err != -EBUSY)
440 		return pkcs1pad_encrypt_sign_complete(req, err);
441 
442 	return err;
443 }
444 
pkcs1pad_verify_complete(struct akcipher_request * req,int err)445 static int pkcs1pad_verify_complete(struct akcipher_request *req, int err)
446 {
447 	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
448 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
449 	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
450 	struct akcipher_instance *inst = akcipher_alg_instance(tfm);
451 	struct pkcs1pad_inst_ctx *ictx = akcipher_instance_ctx(inst);
452 	const struct rsa_asn1_template *digest_info = ictx->digest_info;
453 	unsigned int dst_len;
454 	unsigned int pos;
455 	u8 *out_buf;
456 
457 	if (err)
458 		goto done;
459 
460 	err = -EINVAL;
461 	dst_len = req_ctx->child_req.dst_len;
462 	if (dst_len < ctx->key_size - 1)
463 		goto done;
464 
465 	out_buf = req_ctx->out_buf;
466 	if (dst_len == ctx->key_size) {
467 		if (out_buf[0] != 0x00)
468 			/* Decrypted value had no leading 0 byte */
469 			goto done;
470 
471 		dst_len--;
472 		out_buf++;
473 	}
474 
475 	err = -EBADMSG;
476 	if (out_buf[0] != 0x01)
477 		goto done;
478 
479 	for (pos = 1; pos < dst_len; pos++)
480 		if (out_buf[pos] != 0xff)
481 			break;
482 
483 	if (pos < 9 || pos == dst_len || out_buf[pos] != 0x00)
484 		goto done;
485 	pos++;
486 
487 	if (crypto_memneq(out_buf + pos, digest_info->data, digest_info->size))
488 		goto done;
489 
490 	pos += digest_info->size;
491 
492 	err = 0;
493 
494 	if (req->dst_len < dst_len - pos)
495 		err = -EOVERFLOW;
496 	req->dst_len = dst_len - pos;
497 
498 	if (!err)
499 		sg_copy_from_buffer(req->dst,
500 				sg_nents_for_len(req->dst, req->dst_len),
501 				out_buf + pos, req->dst_len);
502 done:
503 	kzfree(req_ctx->out_buf);
504 
505 	return err;
506 }
507 
pkcs1pad_verify_complete_cb(struct crypto_async_request * child_async_req,int err)508 static void pkcs1pad_verify_complete_cb(
509 		struct crypto_async_request *child_async_req, int err)
510 {
511 	struct akcipher_request *req = child_async_req->data;
512 	struct crypto_async_request async_req;
513 
514 	if (err == -EINPROGRESS)
515 		return;
516 
517 	async_req.data = req->base.data;
518 	async_req.tfm = crypto_akcipher_tfm(crypto_akcipher_reqtfm(req));
519 	async_req.flags = child_async_req->flags;
520 	req->base.complete(&async_req, pkcs1pad_verify_complete(req, err));
521 }
522 
523 /*
524  * The verify operation is here for completeness similar to the verification
525  * defined in RFC2313 section 10.2 except that block type 0 is not accepted,
526  * as in RFC2437.  RFC2437 section 9.2 doesn't define any operation to
527  * retrieve the DigestInfo from a signature, instead the user is expected
528  * to call the sign operation to generate the expected signature and compare
529  * signatures instead of the message-digests.
530  */
pkcs1pad_verify(struct akcipher_request * req)531 static int pkcs1pad_verify(struct akcipher_request *req)
532 {
533 	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
534 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
535 	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
536 	int err;
537 
538 	if (!ctx->key_size || req->src_len < ctx->key_size)
539 		return -EINVAL;
540 
541 	req_ctx->out_buf = kmalloc(ctx->key_size, GFP_KERNEL);
542 	if (!req_ctx->out_buf)
543 		return -ENOMEM;
544 
545 	pkcs1pad_sg_set_buf(req_ctx->out_sg, req_ctx->out_buf,
546 			    ctx->key_size, NULL);
547 
548 	akcipher_request_set_tfm(&req_ctx->child_req, ctx->child);
549 	akcipher_request_set_callback(&req_ctx->child_req, req->base.flags,
550 			pkcs1pad_verify_complete_cb, req);
551 
552 	/* Reuse input buffer, output to a new buffer */
553 	akcipher_request_set_crypt(&req_ctx->child_req, req->src,
554 				   req_ctx->out_sg, req->src_len,
555 				   ctx->key_size);
556 
557 	err = crypto_akcipher_verify(&req_ctx->child_req);
558 	if (err != -EINPROGRESS && err != -EBUSY)
559 		return pkcs1pad_verify_complete(req, err);
560 
561 	return err;
562 }
563 
pkcs1pad_init_tfm(struct crypto_akcipher * tfm)564 static int pkcs1pad_init_tfm(struct crypto_akcipher *tfm)
565 {
566 	struct akcipher_instance *inst = akcipher_alg_instance(tfm);
567 	struct pkcs1pad_inst_ctx *ictx = akcipher_instance_ctx(inst);
568 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
569 	struct crypto_akcipher *child_tfm;
570 
571 	child_tfm = crypto_spawn_akcipher(&ictx->spawn);
572 	if (IS_ERR(child_tfm))
573 		return PTR_ERR(child_tfm);
574 
575 	ctx->child = child_tfm;
576 	return 0;
577 }
578 
pkcs1pad_exit_tfm(struct crypto_akcipher * tfm)579 static void pkcs1pad_exit_tfm(struct crypto_akcipher *tfm)
580 {
581 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
582 
583 	crypto_free_akcipher(ctx->child);
584 }
585 
pkcs1pad_free(struct akcipher_instance * inst)586 static void pkcs1pad_free(struct akcipher_instance *inst)
587 {
588 	struct pkcs1pad_inst_ctx *ctx = akcipher_instance_ctx(inst);
589 	struct crypto_akcipher_spawn *spawn = &ctx->spawn;
590 
591 	crypto_drop_akcipher(spawn);
592 	kfree(inst);
593 }
594 
pkcs1pad_create(struct crypto_template * tmpl,struct rtattr ** tb)595 static int pkcs1pad_create(struct crypto_template *tmpl, struct rtattr **tb)
596 {
597 	const struct rsa_asn1_template *digest_info;
598 	struct crypto_attr_type *algt;
599 	struct akcipher_instance *inst;
600 	struct pkcs1pad_inst_ctx *ctx;
601 	struct crypto_akcipher_spawn *spawn;
602 	struct akcipher_alg *rsa_alg;
603 	const char *rsa_alg_name;
604 	const char *hash_name;
605 	int err;
606 
607 	algt = crypto_get_attr_type(tb);
608 	if (IS_ERR(algt))
609 		return PTR_ERR(algt);
610 
611 	if ((algt->type ^ CRYPTO_ALG_TYPE_AKCIPHER) & algt->mask)
612 		return -EINVAL;
613 
614 	rsa_alg_name = crypto_attr_alg_name(tb[1]);
615 	if (IS_ERR(rsa_alg_name))
616 		return PTR_ERR(rsa_alg_name);
617 
618 	hash_name = crypto_attr_alg_name(tb[2]);
619 	if (IS_ERR(hash_name))
620 		return PTR_ERR(hash_name);
621 
622 	digest_info = rsa_lookup_asn1(hash_name);
623 	if (!digest_info)
624 		return -EINVAL;
625 
626 	inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
627 	if (!inst)
628 		return -ENOMEM;
629 
630 	ctx = akcipher_instance_ctx(inst);
631 	spawn = &ctx->spawn;
632 	ctx->digest_info = digest_info;
633 
634 	crypto_set_spawn(&spawn->base, akcipher_crypto_instance(inst));
635 	err = crypto_grab_akcipher(spawn, rsa_alg_name, 0,
636 			crypto_requires_sync(algt->type, algt->mask));
637 	if (err)
638 		goto out_free_inst;
639 
640 	rsa_alg = crypto_spawn_akcipher_alg(spawn);
641 
642 	err = -ENAMETOOLONG;
643 
644 	if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
645 		     "pkcs1pad(%s,%s)", rsa_alg->base.cra_name, hash_name) >=
646 	    CRYPTO_MAX_ALG_NAME ||
647 	    snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME,
648 		     "pkcs1pad(%s,%s)",
649 		     rsa_alg->base.cra_driver_name, hash_name) >=
650 	    CRYPTO_MAX_ALG_NAME)
651 		goto out_drop_alg;
652 
653 	inst->alg.base.cra_flags = rsa_alg->base.cra_flags & CRYPTO_ALG_ASYNC;
654 	inst->alg.base.cra_priority = rsa_alg->base.cra_priority;
655 	inst->alg.base.cra_ctxsize = sizeof(struct pkcs1pad_ctx);
656 
657 	inst->alg.init = pkcs1pad_init_tfm;
658 	inst->alg.exit = pkcs1pad_exit_tfm;
659 
660 	inst->alg.encrypt = pkcs1pad_encrypt;
661 	inst->alg.decrypt = pkcs1pad_decrypt;
662 	inst->alg.sign = pkcs1pad_sign;
663 	inst->alg.verify = pkcs1pad_verify;
664 	inst->alg.set_pub_key = pkcs1pad_set_pub_key;
665 	inst->alg.set_priv_key = pkcs1pad_set_priv_key;
666 	inst->alg.max_size = pkcs1pad_get_max_size;
667 	inst->alg.reqsize = sizeof(struct pkcs1pad_request) + rsa_alg->reqsize;
668 
669 	inst->free = pkcs1pad_free;
670 
671 	err = akcipher_register_instance(tmpl, inst);
672 	if (err)
673 		goto out_drop_alg;
674 
675 	return 0;
676 
677 out_drop_alg:
678 	crypto_drop_akcipher(spawn);
679 out_free_inst:
680 	kfree(inst);
681 	return err;
682 }
683 
684 struct crypto_template rsa_pkcs1pad_tmpl = {
685 	.name = "pkcs1pad",
686 	.create = pkcs1pad_create,
687 	.module = THIS_MODULE,
688 };
689