xref: /openbmc/linux/crypto/rsa-pkcs1pad.c (revision be709d48) 
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 <crypto/internal/rsa.h>
16 #include <linux/err.h>
17 #include <linux/init.h>
18 #include <linux/kernel.h>
19 #include <linux/module.h>
20 #include <linux/random.h>
21 
22 /*
23  * Hash algorithm OIDs plus ASN.1 DER wrappings [RFC4880 sec 5.2.2].
24  */
25 static const u8 rsa_digest_info_md5[] = {
26 	0x30, 0x20, 0x30, 0x0c, 0x06, 0x08,
27 	0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d, 0x02, 0x05, /* OID */
28 	0x05, 0x00, 0x04, 0x10
29 };
30 
31 static const u8 rsa_digest_info_sha1[] = {
32 	0x30, 0x21, 0x30, 0x09, 0x06, 0x05,
33 	0x2b, 0x0e, 0x03, 0x02, 0x1a,
34 	0x05, 0x00, 0x04, 0x14
35 };
36 
37 static const u8 rsa_digest_info_rmd160[] = {
38 	0x30, 0x21, 0x30, 0x09, 0x06, 0x05,
39 	0x2b, 0x24, 0x03, 0x02, 0x01,
40 	0x05, 0x00, 0x04, 0x14
41 };
42 
43 static const u8 rsa_digest_info_sha224[] = {
44 	0x30, 0x2d, 0x30, 0x0d, 0x06, 0x09,
45 	0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x04,
46 	0x05, 0x00, 0x04, 0x1c
47 };
48 
49 static const u8 rsa_digest_info_sha256[] = {
50 	0x30, 0x31, 0x30, 0x0d, 0x06, 0x09,
51 	0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x01,
52 	0x05, 0x00, 0x04, 0x20
53 };
54 
55 static const u8 rsa_digest_info_sha384[] = {
56 	0x30, 0x41, 0x30, 0x0d, 0x06, 0x09,
57 	0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x02,
58 	0x05, 0x00, 0x04, 0x30
59 };
60 
61 static const u8 rsa_digest_info_sha512[] = {
62 	0x30, 0x51, 0x30, 0x0d, 0x06, 0x09,
63 	0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x03,
64 	0x05, 0x00, 0x04, 0x40
65 };
66 
67 static const struct rsa_asn1_template {
68 	const char	*name;
69 	const u8	*data;
70 	size_t		size;
71 } rsa_asn1_templates[] = {
72 #define _(X) { #X, rsa_digest_info_##X, sizeof(rsa_digest_info_##X) }
73 	_(md5),
74 	_(sha1),
75 	_(rmd160),
76 	_(sha256),
77 	_(sha384),
78 	_(sha512),
79 	_(sha224),
80 	{ NULL }
81 #undef _
82 };
83 
84 static const struct rsa_asn1_template *rsa_lookup_asn1(const char *name)
85 {
86 	const struct rsa_asn1_template *p;
87 
88 	for (p = rsa_asn1_templates; p->name; p++)
89 		if (strcmp(name, p->name) == 0)
90 			return p;
91 	return NULL;
92 }
93 
94 struct pkcs1pad_ctx {
95 	struct crypto_akcipher *child;
96 	unsigned int key_size;
97 };
98 
99 struct pkcs1pad_inst_ctx {
100 	struct crypto_akcipher_spawn spawn;
101 	const struct rsa_asn1_template *digest_info;
102 };
103 
104 struct pkcs1pad_request {
105 	struct scatterlist in_sg[2], out_sg[1];
106 	uint8_t *in_buf, *out_buf;
107 	struct akcipher_request child_req;
108 };
109 
110 static int pkcs1pad_set_pub_key(struct crypto_akcipher *tfm, const void *key,
111 		unsigned int keylen)
112 {
113 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
114 	int err;
115 
116 	ctx->key_size = 0;
117 
118 	err = crypto_akcipher_set_pub_key(ctx->child, key, keylen);
119 	if (err)
120 		return err;
121 
122 	/* Find out new modulus size from rsa implementation */
123 	err = crypto_akcipher_maxsize(ctx->child);
124 	if (err > PAGE_SIZE)
125 		return -ENOTSUPP;
126 
127 	ctx->key_size = err;
128 	return 0;
129 }
130 
131 static int pkcs1pad_set_priv_key(struct crypto_akcipher *tfm, const void *key,
132 		unsigned int keylen)
133 {
134 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
135 	int err;
136 
137 	ctx->key_size = 0;
138 
139 	err = crypto_akcipher_set_priv_key(ctx->child, key, keylen);
140 	if (err)
141 		return err;
142 
143 	/* Find out new modulus size from rsa implementation */
144 	err = crypto_akcipher_maxsize(ctx->child);
145 	if (err > PAGE_SIZE)
146 		return -ENOTSUPP;
147 
148 	ctx->key_size = err;
149 	return 0;
150 }
151 
152 static unsigned int pkcs1pad_get_max_size(struct crypto_akcipher *tfm)
153 {
154 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
155 
156 	/*
157 	 * The maximum destination buffer size for the encrypt/sign operations
158 	 * will be the same as for RSA, even though it's smaller for
159 	 * decrypt/verify.
160 	 */
161 
162 	return ctx->key_size;
163 }
164 
165 static void pkcs1pad_sg_set_buf(struct scatterlist *sg, void *buf, size_t len,
166 		struct scatterlist *next)
167 {
168 	int nsegs = next ? 2 : 1;
169 
170 	sg_init_table(sg, nsegs);
171 	sg_set_buf(sg, buf, len);
172 
173 	if (next)
174 		sg_chain(sg, nsegs, next);
175 }
176 
177 static int pkcs1pad_encrypt_sign_complete(struct akcipher_request *req, int err)
178 {
179 	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
180 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
181 	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
182 	unsigned int pad_len;
183 	unsigned int len;
184 	u8 *out_buf;
185 
186 	if (err)
187 		goto out;
188 
189 	len = req_ctx->child_req.dst_len;
190 	pad_len = ctx->key_size - len;
191 
192 	/* Four billion to one */
193 	if (likely(!pad_len))
194 		goto out;
195 
196 	out_buf = kzalloc(ctx->key_size, GFP_KERNEL);
197 	err = -ENOMEM;
198 	if (!out_buf)
199 		goto out;
200 
201 	sg_copy_to_buffer(req->dst, sg_nents_for_len(req->dst, len),
202 			  out_buf + pad_len, len);
203 	sg_copy_from_buffer(req->dst,
204 			    sg_nents_for_len(req->dst, ctx->key_size),
205 			    out_buf, ctx->key_size);
206 	kzfree(out_buf);
207 
208 out:
209 	req->dst_len = ctx->key_size;
210 
211 	kfree(req_ctx->in_buf);
212 
213 	return err;
214 }
215 
216 static void pkcs1pad_encrypt_sign_complete_cb(
217 		struct crypto_async_request *child_async_req, int err)
218 {
219 	struct akcipher_request *req = child_async_req->data;
220 	struct crypto_async_request async_req;
221 
222 	if (err == -EINPROGRESS)
223 		return;
224 
225 	async_req.data = req->base.data;
226 	async_req.tfm = crypto_akcipher_tfm(crypto_akcipher_reqtfm(req));
227 	async_req.flags = child_async_req->flags;
228 	req->base.complete(&async_req,
229 			pkcs1pad_encrypt_sign_complete(req, err));
230 }
231 
232 static int pkcs1pad_encrypt(struct akcipher_request *req)
233 {
234 	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
235 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
236 	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
237 	int err;
238 	unsigned int i, ps_end;
239 
240 	if (!ctx->key_size)
241 		return -EINVAL;
242 
243 	if (req->src_len > ctx->key_size - 11)
244 		return -EOVERFLOW;
245 
246 	if (req->dst_len < ctx->key_size) {
247 		req->dst_len = ctx->key_size;
248 		return -EOVERFLOW;
249 	}
250 
251 	req_ctx->in_buf = kmalloc(ctx->key_size - 1 - req->src_len,
252 				  GFP_KERNEL);
253 	if (!req_ctx->in_buf)
254 		return -ENOMEM;
255 
256 	ps_end = ctx->key_size - req->src_len - 2;
257 	req_ctx->in_buf[0] = 0x02;
258 	for (i = 1; i < ps_end; i++)
259 		req_ctx->in_buf[i] = 1 + prandom_u32_max(255);
260 	req_ctx->in_buf[ps_end] = 0x00;
261 
262 	pkcs1pad_sg_set_buf(req_ctx->in_sg, req_ctx->in_buf,
263 			ctx->key_size - 1 - req->src_len, req->src);
264 
265 	akcipher_request_set_tfm(&req_ctx->child_req, ctx->child);
266 	akcipher_request_set_callback(&req_ctx->child_req, req->base.flags,
267 			pkcs1pad_encrypt_sign_complete_cb, req);
268 
269 	/* Reuse output buffer */
270 	akcipher_request_set_crypt(&req_ctx->child_req, req_ctx->in_sg,
271 				   req->dst, ctx->key_size - 1, req->dst_len);
272 
273 	err = crypto_akcipher_encrypt(&req_ctx->child_req);
274 	if (err != -EINPROGRESS && err != -EBUSY)
275 		return pkcs1pad_encrypt_sign_complete(req, err);
276 
277 	return err;
278 }
279 
280 static int pkcs1pad_decrypt_complete(struct akcipher_request *req, int err)
281 {
282 	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
283 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
284 	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
285 	unsigned int dst_len;
286 	unsigned int pos;
287 	u8 *out_buf;
288 
289 	if (err)
290 		goto done;
291 
292 	err = -EINVAL;
293 	dst_len = req_ctx->child_req.dst_len;
294 	if (dst_len < ctx->key_size - 1)
295 		goto done;
296 
297 	out_buf = req_ctx->out_buf;
298 	if (dst_len == ctx->key_size) {
299 		if (out_buf[0] != 0x00)
300 			/* Decrypted value had no leading 0 byte */
301 			goto done;
302 
303 		dst_len--;
304 		out_buf++;
305 	}
306 
307 	if (out_buf[0] != 0x02)
308 		goto done;
309 
310 	for (pos = 1; pos < dst_len; pos++)
311 		if (out_buf[pos] == 0x00)
312 			break;
313 	if (pos < 9 || pos == dst_len)
314 		goto done;
315 	pos++;
316 
317 	err = 0;
318 
319 	if (req->dst_len < dst_len - pos)
320 		err = -EOVERFLOW;
321 	req->dst_len = dst_len - pos;
322 
323 	if (!err)
324 		sg_copy_from_buffer(req->dst,
325 				sg_nents_for_len(req->dst, req->dst_len),
326 				out_buf + pos, req->dst_len);
327 
328 done:
329 	kzfree(req_ctx->out_buf);
330 
331 	return err;
332 }
333 
334 static void pkcs1pad_decrypt_complete_cb(
335 		struct crypto_async_request *child_async_req, int err)
336 {
337 	struct akcipher_request *req = child_async_req->data;
338 	struct crypto_async_request async_req;
339 
340 	if (err == -EINPROGRESS)
341 		return;
342 
343 	async_req.data = req->base.data;
344 	async_req.tfm = crypto_akcipher_tfm(crypto_akcipher_reqtfm(req));
345 	async_req.flags = child_async_req->flags;
346 	req->base.complete(&async_req, pkcs1pad_decrypt_complete(req, err));
347 }
348 
349 static int pkcs1pad_decrypt(struct akcipher_request *req)
350 {
351 	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
352 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
353 	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
354 	int err;
355 
356 	if (!ctx->key_size || req->src_len != ctx->key_size)
357 		return -EINVAL;
358 
359 	req_ctx->out_buf = kmalloc(ctx->key_size, GFP_KERNEL);
360 	if (!req_ctx->out_buf)
361 		return -ENOMEM;
362 
363 	pkcs1pad_sg_set_buf(req_ctx->out_sg, req_ctx->out_buf,
364 			    ctx->key_size, NULL);
365 
366 	akcipher_request_set_tfm(&req_ctx->child_req, ctx->child);
367 	akcipher_request_set_callback(&req_ctx->child_req, req->base.flags,
368 			pkcs1pad_decrypt_complete_cb, req);
369 
370 	/* Reuse input buffer, output to a new buffer */
371 	akcipher_request_set_crypt(&req_ctx->child_req, req->src,
372 				   req_ctx->out_sg, req->src_len,
373 				   ctx->key_size);
374 
375 	err = crypto_akcipher_decrypt(&req_ctx->child_req);
376 	if (err != -EINPROGRESS && err != -EBUSY)
377 		return pkcs1pad_decrypt_complete(req, err);
378 
379 	return err;
380 }
381 
382 static int pkcs1pad_sign(struct akcipher_request *req)
383 {
384 	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
385 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
386 	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
387 	struct akcipher_instance *inst = akcipher_alg_instance(tfm);
388 	struct pkcs1pad_inst_ctx *ictx = akcipher_instance_ctx(inst);
389 	const struct rsa_asn1_template *digest_info = ictx->digest_info;
390 	int err;
391 	unsigned int ps_end, digest_size = 0;
392 
393 	if (!ctx->key_size)
394 		return -EINVAL;
395 
396 	if (digest_info)
397 		digest_size = digest_info->size;
398 
399 	if (req->src_len + digest_size > ctx->key_size - 11)
400 		return -EOVERFLOW;
401 
402 	if (req->dst_len < ctx->key_size) {
403 		req->dst_len = ctx->key_size;
404 		return -EOVERFLOW;
405 	}
406 
407 	req_ctx->in_buf = kmalloc(ctx->key_size - 1 - req->src_len,
408 				  GFP_KERNEL);
409 	if (!req_ctx->in_buf)
410 		return -ENOMEM;
411 
412 	ps_end = ctx->key_size - digest_size - req->src_len - 2;
413 	req_ctx->in_buf[0] = 0x01;
414 	memset(req_ctx->in_buf + 1, 0xff, ps_end - 1);
415 	req_ctx->in_buf[ps_end] = 0x00;
416 
417 	if (digest_info)
418 		memcpy(req_ctx->in_buf + ps_end + 1, digest_info->data,
419 		       digest_info->size);
420 
421 	pkcs1pad_sg_set_buf(req_ctx->in_sg, req_ctx->in_buf,
422 			ctx->key_size - 1 - req->src_len, req->src);
423 
424 	akcipher_request_set_tfm(&req_ctx->child_req, ctx->child);
425 	akcipher_request_set_callback(&req_ctx->child_req, req->base.flags,
426 			pkcs1pad_encrypt_sign_complete_cb, req);
427 
428 	/* Reuse output buffer */
429 	akcipher_request_set_crypt(&req_ctx->child_req, req_ctx->in_sg,
430 				   req->dst, ctx->key_size - 1, req->dst_len);
431 
432 	err = crypto_akcipher_sign(&req_ctx->child_req);
433 	if (err != -EINPROGRESS && err != -EBUSY)
434 		return pkcs1pad_encrypt_sign_complete(req, err);
435 
436 	return err;
437 }
438 
439 static int pkcs1pad_verify_complete(struct akcipher_request *req, int err)
440 {
441 	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
442 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
443 	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
444 	struct akcipher_instance *inst = akcipher_alg_instance(tfm);
445 	struct pkcs1pad_inst_ctx *ictx = akcipher_instance_ctx(inst);
446 	const struct rsa_asn1_template *digest_info = ictx->digest_info;
447 	unsigned int dst_len;
448 	unsigned int pos;
449 	u8 *out_buf;
450 
451 	if (err)
452 		goto done;
453 
454 	err = -EINVAL;
455 	dst_len = req_ctx->child_req.dst_len;
456 	if (dst_len < ctx->key_size - 1)
457 		goto done;
458 
459 	out_buf = req_ctx->out_buf;
460 	if (dst_len == ctx->key_size) {
461 		if (out_buf[0] != 0x00)
462 			/* Decrypted value had no leading 0 byte */
463 			goto done;
464 
465 		dst_len--;
466 		out_buf++;
467 	}
468 
469 	err = -EBADMSG;
470 	if (out_buf[0] != 0x01)
471 		goto done;
472 
473 	for (pos = 1; pos < dst_len; pos++)
474 		if (out_buf[pos] != 0xff)
475 			break;
476 
477 	if (pos < 9 || pos == dst_len || out_buf[pos] != 0x00)
478 		goto done;
479 	pos++;
480 
481 	if (digest_info) {
482 		if (crypto_memneq(out_buf + pos, digest_info->data,
483 				  digest_info->size))
484 			goto done;
485 
486 		pos += digest_info->size;
487 	}
488 
489 	err = 0;
490 
491 	if (req->dst_len < dst_len - pos)
492 		err = -EOVERFLOW;
493 	req->dst_len = dst_len - pos;
494 
495 	if (!err)
496 		sg_copy_from_buffer(req->dst,
497 				sg_nents_for_len(req->dst, req->dst_len),
498 				out_buf + pos, req->dst_len);
499 done:
500 	kzfree(req_ctx->out_buf);
501 
502 	return err;
503 }
504 
505 static void pkcs1pad_verify_complete_cb(
506 		struct crypto_async_request *child_async_req, int err)
507 {
508 	struct akcipher_request *req = child_async_req->data;
509 	struct crypto_async_request async_req;
510 
511 	if (err == -EINPROGRESS)
512 		return;
513 
514 	async_req.data = req->base.data;
515 	async_req.tfm = crypto_akcipher_tfm(crypto_akcipher_reqtfm(req));
516 	async_req.flags = child_async_req->flags;
517 	req->base.complete(&async_req, pkcs1pad_verify_complete(req, err));
518 }
519 
520 /*
521  * The verify operation is here for completeness similar to the verification
522  * defined in RFC2313 section 10.2 except that block type 0 is not accepted,
523  * as in RFC2437.  RFC2437 section 9.2 doesn't define any operation to
524  * retrieve the DigestInfo from a signature, instead the user is expected
525  * to call the sign operation to generate the expected signature and compare
526  * signatures instead of the message-digests.
527  */
528 static int pkcs1pad_verify(struct akcipher_request *req)
529 {
530 	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
531 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
532 	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
533 	int err;
534 
535 	if (!ctx->key_size || req->src_len < ctx->key_size)
536 		return -EINVAL;
537 
538 	req_ctx->out_buf = kmalloc(ctx->key_size, GFP_KERNEL);
539 	if (!req_ctx->out_buf)
540 		return -ENOMEM;
541 
542 	pkcs1pad_sg_set_buf(req_ctx->out_sg, req_ctx->out_buf,
543 			    ctx->key_size, NULL);
544 
545 	akcipher_request_set_tfm(&req_ctx->child_req, ctx->child);
546 	akcipher_request_set_callback(&req_ctx->child_req, req->base.flags,
547 			pkcs1pad_verify_complete_cb, req);
548 
549 	/* Reuse input buffer, output to a new buffer */
550 	akcipher_request_set_crypt(&req_ctx->child_req, req->src,
551 				   req_ctx->out_sg, req->src_len,
552 				   ctx->key_size);
553 
554 	err = crypto_akcipher_verify(&req_ctx->child_req);
555 	if (err != -EINPROGRESS && err != -EBUSY)
556 		return pkcs1pad_verify_complete(req, err);
557 
558 	return err;
559 }
560 
561 static int pkcs1pad_init_tfm(struct crypto_akcipher *tfm)
562 {
563 	struct akcipher_instance *inst = akcipher_alg_instance(tfm);
564 	struct pkcs1pad_inst_ctx *ictx = akcipher_instance_ctx(inst);
565 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
566 	struct crypto_akcipher *child_tfm;
567 
568 	child_tfm = crypto_spawn_akcipher(&ictx->spawn);
569 	if (IS_ERR(child_tfm))
570 		return PTR_ERR(child_tfm);
571 
572 	ctx->child = child_tfm;
573 	return 0;
574 }
575 
576 static void pkcs1pad_exit_tfm(struct crypto_akcipher *tfm)
577 {
578 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
579 
580 	crypto_free_akcipher(ctx->child);
581 }
582 
583 static void pkcs1pad_free(struct akcipher_instance *inst)
584 {
585 	struct pkcs1pad_inst_ctx *ctx = akcipher_instance_ctx(inst);
586 	struct crypto_akcipher_spawn *spawn = &ctx->spawn;
587 
588 	crypto_drop_akcipher(spawn);
589 	kfree(inst);
590 }
591 
592 static int pkcs1pad_create(struct crypto_template *tmpl, struct rtattr **tb)
593 {
594 	const struct rsa_asn1_template *digest_info;
595 	struct crypto_attr_type *algt;
596 	struct akcipher_instance *inst;
597 	struct pkcs1pad_inst_ctx *ctx;
598 	struct crypto_akcipher_spawn *spawn;
599 	struct akcipher_alg *rsa_alg;
600 	const char *rsa_alg_name;
601 	const char *hash_name;
602 	int err;
603 
604 	algt = crypto_get_attr_type(tb);
605 	if (IS_ERR(algt))
606 		return PTR_ERR(algt);
607 
608 	if ((algt->type ^ CRYPTO_ALG_TYPE_AKCIPHER) & algt->mask)
609 		return -EINVAL;
610 
611 	rsa_alg_name = crypto_attr_alg_name(tb[1]);
612 	if (IS_ERR(rsa_alg_name))
613 		return PTR_ERR(rsa_alg_name);
614 
615 	hash_name = crypto_attr_alg_name(tb[2]);
616 	if (IS_ERR(hash_name))
617 		hash_name = NULL;
618 
619 	if (hash_name) {
620 		digest_info = rsa_lookup_asn1(hash_name);
621 		if (!digest_info)
622 			return -EINVAL;
623 	} else
624 		digest_info = NULL;
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 (!hash_name) {
645 		if (snprintf(inst->alg.base.cra_name,
646 			     CRYPTO_MAX_ALG_NAME, "pkcs1pad(%s)",
647 			     rsa_alg->base.cra_name) >= CRYPTO_MAX_ALG_NAME)
648 			goto out_drop_alg;
649 
650 		if (snprintf(inst->alg.base.cra_driver_name,
651 			     CRYPTO_MAX_ALG_NAME, "pkcs1pad(%s)",
652 			     rsa_alg->base.cra_driver_name) >=
653 			     CRYPTO_MAX_ALG_NAME)
654 			goto out_drop_alg;
655 	} else {
656 		if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
657 			     "pkcs1pad(%s,%s)", rsa_alg->base.cra_name,
658 			     hash_name) >= CRYPTO_MAX_ALG_NAME)
659 			goto out_drop_alg;
660 
661 		if (snprintf(inst->alg.base.cra_driver_name,
662 			     CRYPTO_MAX_ALG_NAME, "pkcs1pad(%s,%s)",
663 			     rsa_alg->base.cra_driver_name,
664 			     hash_name) >= CRYPTO_MAX_ALG_NAME)
665 			goto out_drop_alg;
666 	}
667 
668 	inst->alg.base.cra_flags = rsa_alg->base.cra_flags & CRYPTO_ALG_ASYNC;
669 	inst->alg.base.cra_priority = rsa_alg->base.cra_priority;
670 	inst->alg.base.cra_ctxsize = sizeof(struct pkcs1pad_ctx);
671 
672 	inst->alg.init = pkcs1pad_init_tfm;
673 	inst->alg.exit = pkcs1pad_exit_tfm;
674 
675 	inst->alg.encrypt = pkcs1pad_encrypt;
676 	inst->alg.decrypt = pkcs1pad_decrypt;
677 	inst->alg.sign = pkcs1pad_sign;
678 	inst->alg.verify = pkcs1pad_verify;
679 	inst->alg.set_pub_key = pkcs1pad_set_pub_key;
680 	inst->alg.set_priv_key = pkcs1pad_set_priv_key;
681 	inst->alg.max_size = pkcs1pad_get_max_size;
682 	inst->alg.reqsize = sizeof(struct pkcs1pad_request) + rsa_alg->reqsize;
683 
684 	inst->free = pkcs1pad_free;
685 
686 	err = akcipher_register_instance(tmpl, inst);
687 	if (err)
688 		goto out_drop_alg;
689 
690 	return 0;
691 
692 out_drop_alg:
693 	crypto_drop_akcipher(spawn);
694 out_free_inst:
695 	kfree(inst);
696 	return err;
697 }
698 
699 struct crypto_template rsa_pkcs1pad_tmpl = {
700 	.name = "pkcs1pad",
701 	.create = pkcs1pad_create,
702 	.module = THIS_MODULE,
703 };
704