xref: /openbmc/linux/crypto/rsa-pkcs1pad.c (revision d4295e12) 
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 
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 
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 
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 
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 
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 
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 
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 
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 	akcipher_request_set_tfm(&req_ctx->child_req, ctx->child);
265 	akcipher_request_set_callback(&req_ctx->child_req, req->base.flags,
266 			pkcs1pad_encrypt_sign_complete_cb, req);
267 
268 	/* Reuse output buffer */
269 	akcipher_request_set_crypt(&req_ctx->child_req, req_ctx->in_sg,
270 				   req->dst, ctx->key_size - 1, req->dst_len);
271 
272 	err = crypto_akcipher_encrypt(&req_ctx->child_req);
273 	if (err != -EINPROGRESS && err != -EBUSY)
274 		return pkcs1pad_encrypt_sign_complete(req, err);
275 
276 	return err;
277 }
278 
279 static int pkcs1pad_decrypt_complete(struct akcipher_request *req, int err)
280 {
281 	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
282 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
283 	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
284 	unsigned int dst_len;
285 	unsigned int pos;
286 	u8 *out_buf;
287 
288 	if (err)
289 		goto done;
290 
291 	err = -EINVAL;
292 	dst_len = req_ctx->child_req.dst_len;
293 	if (dst_len < ctx->key_size - 1)
294 		goto done;
295 
296 	out_buf = req_ctx->out_buf;
297 	if (dst_len == ctx->key_size) {
298 		if (out_buf[0] != 0x00)
299 			/* Decrypted value had no leading 0 byte */
300 			goto done;
301 
302 		dst_len--;
303 		out_buf++;
304 	}
305 
306 	if (out_buf[0] != 0x02)
307 		goto done;
308 
309 	for (pos = 1; pos < dst_len; pos++)
310 		if (out_buf[pos] == 0x00)
311 			break;
312 	if (pos < 9 || pos == dst_len)
313 		goto done;
314 	pos++;
315 
316 	err = 0;
317 
318 	if (req->dst_len < dst_len - pos)
319 		err = -EOVERFLOW;
320 	req->dst_len = dst_len - pos;
321 
322 	if (!err)
323 		sg_copy_from_buffer(req->dst,
324 				sg_nents_for_len(req->dst, req->dst_len),
325 				out_buf + pos, req->dst_len);
326 
327 done:
328 	kzfree(req_ctx->out_buf);
329 
330 	return err;
331 }
332 
333 static void pkcs1pad_decrypt_complete_cb(
334 		struct crypto_async_request *child_async_req, int err)
335 {
336 	struct akcipher_request *req = child_async_req->data;
337 	struct crypto_async_request async_req;
338 
339 	if (err == -EINPROGRESS)
340 		return;
341 
342 	async_req.data = req->base.data;
343 	async_req.tfm = crypto_akcipher_tfm(crypto_akcipher_reqtfm(req));
344 	async_req.flags = child_async_req->flags;
345 	req->base.complete(&async_req, pkcs1pad_decrypt_complete(req, err));
346 }
347 
348 static int pkcs1pad_decrypt(struct akcipher_request *req)
349 {
350 	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
351 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
352 	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
353 	int err;
354 
355 	if (!ctx->key_size || req->src_len != ctx->key_size)
356 		return -EINVAL;
357 
358 	req_ctx->out_buf = kmalloc(ctx->key_size, GFP_KERNEL);
359 	if (!req_ctx->out_buf)
360 		return -ENOMEM;
361 
362 	pkcs1pad_sg_set_buf(req_ctx->out_sg, req_ctx->out_buf,
363 			    ctx->key_size, NULL);
364 
365 	akcipher_request_set_tfm(&req_ctx->child_req, ctx->child);
366 	akcipher_request_set_callback(&req_ctx->child_req, req->base.flags,
367 			pkcs1pad_decrypt_complete_cb, req);
368 
369 	/* Reuse input buffer, output to a new buffer */
370 	akcipher_request_set_crypt(&req_ctx->child_req, req->src,
371 				   req_ctx->out_sg, req->src_len,
372 				   ctx->key_size);
373 
374 	err = crypto_akcipher_decrypt(&req_ctx->child_req);
375 	if (err != -EINPROGRESS && err != -EBUSY)
376 		return pkcs1pad_decrypt_complete(req, err);
377 
378 	return err;
379 }
380 
381 static int pkcs1pad_sign(struct akcipher_request *req)
382 {
383 	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
384 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
385 	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
386 	struct akcipher_instance *inst = akcipher_alg_instance(tfm);
387 	struct pkcs1pad_inst_ctx *ictx = akcipher_instance_ctx(inst);
388 	const struct rsa_asn1_template *digest_info = ictx->digest_info;
389 	int err;
390 	unsigned int ps_end, digest_size = 0;
391 
392 	if (!ctx->key_size)
393 		return -EINVAL;
394 
395 	if (digest_info)
396 		digest_size = digest_info->size;
397 
398 	if (req->src_len + digest_size > ctx->key_size - 11)
399 		return -EOVERFLOW;
400 
401 	if (req->dst_len < ctx->key_size) {
402 		req->dst_len = ctx->key_size;
403 		return -EOVERFLOW;
404 	}
405 
406 	req_ctx->in_buf = kmalloc(ctx->key_size - 1 - req->src_len,
407 				  GFP_KERNEL);
408 	if (!req_ctx->in_buf)
409 		return -ENOMEM;
410 
411 	ps_end = ctx->key_size - digest_size - req->src_len - 2;
412 	req_ctx->in_buf[0] = 0x01;
413 	memset(req_ctx->in_buf + 1, 0xff, ps_end - 1);
414 	req_ctx->in_buf[ps_end] = 0x00;
415 
416 	if (digest_info)
417 		memcpy(req_ctx->in_buf + ps_end + 1, digest_info->data,
418 		       digest_info->size);
419 
420 	pkcs1pad_sg_set_buf(req_ctx->in_sg, req_ctx->in_buf,
421 			ctx->key_size - 1 - req->src_len, req->src);
422 
423 	akcipher_request_set_tfm(&req_ctx->child_req, ctx->child);
424 	akcipher_request_set_callback(&req_ctx->child_req, req->base.flags,
425 			pkcs1pad_encrypt_sign_complete_cb, req);
426 
427 	/* Reuse output buffer */
428 	akcipher_request_set_crypt(&req_ctx->child_req, req_ctx->in_sg,
429 				   req->dst, ctx->key_size - 1, req->dst_len);
430 
431 	err = crypto_akcipher_sign(&req_ctx->child_req);
432 	if (err != -EINPROGRESS && err != -EBUSY)
433 		return pkcs1pad_encrypt_sign_complete(req, err);
434 
435 	return err;
436 }
437 
438 static int pkcs1pad_verify_complete(struct akcipher_request *req, int err)
439 {
440 	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
441 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
442 	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
443 	struct akcipher_instance *inst = akcipher_alg_instance(tfm);
444 	struct pkcs1pad_inst_ctx *ictx = akcipher_instance_ctx(inst);
445 	const struct rsa_asn1_template *digest_info = ictx->digest_info;
446 	unsigned int dst_len;
447 	unsigned int pos;
448 	u8 *out_buf;
449 
450 	if (err)
451 		goto done;
452 
453 	err = -EINVAL;
454 	dst_len = req_ctx->child_req.dst_len;
455 	if (dst_len < ctx->key_size - 1)
456 		goto done;
457 
458 	out_buf = req_ctx->out_buf;
459 	if (dst_len == ctx->key_size) {
460 		if (out_buf[0] != 0x00)
461 			/* Decrypted value had no leading 0 byte */
462 			goto done;
463 
464 		dst_len--;
465 		out_buf++;
466 	}
467 
468 	err = -EBADMSG;
469 	if (out_buf[0] != 0x01)
470 		goto done;
471 
472 	for (pos = 1; pos < dst_len; pos++)
473 		if (out_buf[pos] != 0xff)
474 			break;
475 
476 	if (pos < 9 || pos == dst_len || out_buf[pos] != 0x00)
477 		goto done;
478 	pos++;
479 
480 	if (digest_info) {
481 		if (crypto_memneq(out_buf + pos, digest_info->data,
482 				  digest_info->size))
483 			goto done;
484 
485 		pos += digest_info->size;
486 	}
487 
488 	err = 0;
489 
490 	if (req->dst_len < dst_len - pos)
491 		err = -EOVERFLOW;
492 	req->dst_len = dst_len - pos;
493 
494 	if (!err)
495 		sg_copy_from_buffer(req->dst,
496 				sg_nents_for_len(req->dst, req->dst_len),
497 				out_buf + pos, req->dst_len);
498 done:
499 	kzfree(req_ctx->out_buf);
500 
501 	return err;
502 }
503 
504 static void pkcs1pad_verify_complete_cb(
505 		struct crypto_async_request *child_async_req, int err)
506 {
507 	struct akcipher_request *req = child_async_req->data;
508 	struct crypto_async_request async_req;
509 
510 	if (err == -EINPROGRESS)
511 		return;
512 
513 	async_req.data = req->base.data;
514 	async_req.tfm = crypto_akcipher_tfm(crypto_akcipher_reqtfm(req));
515 	async_req.flags = child_async_req->flags;
516 	req->base.complete(&async_req, pkcs1pad_verify_complete(req, err));
517 }
518 
519 /*
520  * The verify operation is here for completeness similar to the verification
521  * defined in RFC2313 section 10.2 except that block type 0 is not accepted,
522  * as in RFC2437.  RFC2437 section 9.2 doesn't define any operation to
523  * retrieve the DigestInfo from a signature, instead the user is expected
524  * to call the sign operation to generate the expected signature and compare
525  * signatures instead of the message-digests.
526  */
527 static int pkcs1pad_verify(struct akcipher_request *req)
528 {
529 	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
530 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
531 	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
532 	int err;
533 
534 	if (!ctx->key_size || req->src_len < ctx->key_size)
535 		return -EINVAL;
536 
537 	req_ctx->out_buf = kmalloc(ctx->key_size, GFP_KERNEL);
538 	if (!req_ctx->out_buf)
539 		return -ENOMEM;
540 
541 	pkcs1pad_sg_set_buf(req_ctx->out_sg, req_ctx->out_buf,
542 			    ctx->key_size, NULL);
543 
544 	akcipher_request_set_tfm(&req_ctx->child_req, ctx->child);
545 	akcipher_request_set_callback(&req_ctx->child_req, req->base.flags,
546 			pkcs1pad_verify_complete_cb, req);
547 
548 	/* Reuse input buffer, output to a new buffer */
549 	akcipher_request_set_crypt(&req_ctx->child_req, req->src,
550 				   req_ctx->out_sg, req->src_len,
551 				   ctx->key_size);
552 
553 	err = crypto_akcipher_verify(&req_ctx->child_req);
554 	if (err != -EINPROGRESS && err != -EBUSY)
555 		return pkcs1pad_verify_complete(req, err);
556 
557 	return err;
558 }
559 
560 static int pkcs1pad_init_tfm(struct crypto_akcipher *tfm)
561 {
562 	struct akcipher_instance *inst = akcipher_alg_instance(tfm);
563 	struct pkcs1pad_inst_ctx *ictx = akcipher_instance_ctx(inst);
564 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
565 	struct crypto_akcipher *child_tfm;
566 
567 	child_tfm = crypto_spawn_akcipher(&ictx->spawn);
568 	if (IS_ERR(child_tfm))
569 		return PTR_ERR(child_tfm);
570 
571 	ctx->child = child_tfm;
572 	return 0;
573 }
574 
575 static void pkcs1pad_exit_tfm(struct crypto_akcipher *tfm)
576 {
577 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
578 
579 	crypto_free_akcipher(ctx->child);
580 }
581 
582 static void pkcs1pad_free(struct akcipher_instance *inst)
583 {
584 	struct pkcs1pad_inst_ctx *ctx = akcipher_instance_ctx(inst);
585 	struct crypto_akcipher_spawn *spawn = &ctx->spawn;
586 
587 	crypto_drop_akcipher(spawn);
588 	kfree(inst);
589 }
590 
591 static int pkcs1pad_create(struct crypto_template *tmpl, struct rtattr **tb)
592 {
593 	const struct rsa_asn1_template *digest_info;
594 	struct crypto_attr_type *algt;
595 	struct akcipher_instance *inst;
596 	struct pkcs1pad_inst_ctx *ctx;
597 	struct crypto_akcipher_spawn *spawn;
598 	struct akcipher_alg *rsa_alg;
599 	const char *rsa_alg_name;
600 	const char *hash_name;
601 	int err;
602 
603 	algt = crypto_get_attr_type(tb);
604 	if (IS_ERR(algt))
605 		return PTR_ERR(algt);
606 
607 	if ((algt->type ^ CRYPTO_ALG_TYPE_AKCIPHER) & algt->mask)
608 		return -EINVAL;
609 
610 	rsa_alg_name = crypto_attr_alg_name(tb[1]);
611 	if (IS_ERR(rsa_alg_name))
612 		return PTR_ERR(rsa_alg_name);
613 
614 	hash_name = crypto_attr_alg_name(tb[2]);
615 	if (IS_ERR(hash_name))
616 		hash_name = NULL;
617 
618 	if (hash_name) {
619 		digest_info = rsa_lookup_asn1(hash_name);
620 		if (!digest_info)
621 			return -EINVAL;
622 	} else
623 		digest_info = NULL;
624 
625 	inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
626 	if (!inst)
627 		return -ENOMEM;
628 
629 	ctx = akcipher_instance_ctx(inst);
630 	spawn = &ctx->spawn;
631 	ctx->digest_info = digest_info;
632 
633 	crypto_set_spawn(&spawn->base, akcipher_crypto_instance(inst));
634 	err = crypto_grab_akcipher(spawn, rsa_alg_name, 0,
635 			crypto_requires_sync(algt->type, algt->mask));
636 	if (err)
637 		goto out_free_inst;
638 
639 	rsa_alg = crypto_spawn_akcipher_alg(spawn);
640 
641 	err = -ENAMETOOLONG;
642 
643 	if (!hash_name) {
644 		if (snprintf(inst->alg.base.cra_name,
645 			     CRYPTO_MAX_ALG_NAME, "pkcs1pad(%s)",
646 			     rsa_alg->base.cra_name) >= CRYPTO_MAX_ALG_NAME)
647 			goto out_drop_alg;
648 
649 		if (snprintf(inst->alg.base.cra_driver_name,
650 			     CRYPTO_MAX_ALG_NAME, "pkcs1pad(%s)",
651 			     rsa_alg->base.cra_driver_name) >=
652 			     CRYPTO_MAX_ALG_NAME)
653 			goto out_drop_alg;
654 	} else {
655 		if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
656 			     "pkcs1pad(%s,%s)", rsa_alg->base.cra_name,
657 			     hash_name) >= CRYPTO_MAX_ALG_NAME)
658 			goto out_drop_alg;
659 
660 		if (snprintf(inst->alg.base.cra_driver_name,
661 			     CRYPTO_MAX_ALG_NAME, "pkcs1pad(%s,%s)",
662 			     rsa_alg->base.cra_driver_name,
663 			     hash_name) >= CRYPTO_MAX_ALG_NAME)
664 			goto out_drop_alg;
665 	}
666 
667 	inst->alg.base.cra_flags = rsa_alg->base.cra_flags & CRYPTO_ALG_ASYNC;
668 	inst->alg.base.cra_priority = rsa_alg->base.cra_priority;
669 	inst->alg.base.cra_ctxsize = sizeof(struct pkcs1pad_ctx);
670 
671 	inst->alg.init = pkcs1pad_init_tfm;
672 	inst->alg.exit = pkcs1pad_exit_tfm;
673 
674 	inst->alg.encrypt = pkcs1pad_encrypt;
675 	inst->alg.decrypt = pkcs1pad_decrypt;
676 	inst->alg.sign = pkcs1pad_sign;
677 	inst->alg.verify = pkcs1pad_verify;
678 	inst->alg.set_pub_key = pkcs1pad_set_pub_key;
679 	inst->alg.set_priv_key = pkcs1pad_set_priv_key;
680 	inst->alg.max_size = pkcs1pad_get_max_size;
681 	inst->alg.reqsize = sizeof(struct pkcs1pad_request) + rsa_alg->reqsize;
682 
683 	inst->free = pkcs1pad_free;
684 
685 	err = akcipher_register_instance(tmpl, inst);
686 	if (err)
687 		goto out_drop_alg;
688 
689 	return 0;
690 
691 out_drop_alg:
692 	crypto_drop_akcipher(spawn);
693 out_free_inst:
694 	kfree(inst);
695 	return err;
696 }
697 
698 struct crypto_template rsa_pkcs1pad_tmpl = {
699 	.name = "pkcs1pad",
700 	.create = pkcs1pad_create,
701 	.module = THIS_MODULE,
702 };
703