xref: /openbmc/linux/crypto/rsa-pkcs1pad.c (revision f125e2d4) 
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * RSA padding templates.
4  *
5  * Copyright (c) 2015  Intel Corporation
6  */
7 
8 #include <crypto/algapi.h>
9 #include <crypto/akcipher.h>
10 #include <crypto/internal/akcipher.h>
11 #include <crypto/internal/rsa.h>
12 #include <linux/err.h>
13 #include <linux/init.h>
14 #include <linux/kernel.h>
15 #include <linux/module.h>
16 #include <linux/random.h>
17 
18 /*
19  * Hash algorithm OIDs plus ASN.1 DER wrappings [RFC4880 sec 5.2.2].
20  */
21 static const u8 rsa_digest_info_md5[] = {
22 	0x30, 0x20, 0x30, 0x0c, 0x06, 0x08,
23 	0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d, 0x02, 0x05, /* OID */
24 	0x05, 0x00, 0x04, 0x10
25 };
26 
27 static const u8 rsa_digest_info_sha1[] = {
28 	0x30, 0x21, 0x30, 0x09, 0x06, 0x05,
29 	0x2b, 0x0e, 0x03, 0x02, 0x1a,
30 	0x05, 0x00, 0x04, 0x14
31 };
32 
33 static const u8 rsa_digest_info_rmd160[] = {
34 	0x30, 0x21, 0x30, 0x09, 0x06, 0x05,
35 	0x2b, 0x24, 0x03, 0x02, 0x01,
36 	0x05, 0x00, 0x04, 0x14
37 };
38 
39 static const u8 rsa_digest_info_sha224[] = {
40 	0x30, 0x2d, 0x30, 0x0d, 0x06, 0x09,
41 	0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x04,
42 	0x05, 0x00, 0x04, 0x1c
43 };
44 
45 static const u8 rsa_digest_info_sha256[] = {
46 	0x30, 0x31, 0x30, 0x0d, 0x06, 0x09,
47 	0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x01,
48 	0x05, 0x00, 0x04, 0x20
49 };
50 
51 static const u8 rsa_digest_info_sha384[] = {
52 	0x30, 0x41, 0x30, 0x0d, 0x06, 0x09,
53 	0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x02,
54 	0x05, 0x00, 0x04, 0x30
55 };
56 
57 static const u8 rsa_digest_info_sha512[] = {
58 	0x30, 0x51, 0x30, 0x0d, 0x06, 0x09,
59 	0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x03,
60 	0x05, 0x00, 0x04, 0x40
61 };
62 
63 static const struct rsa_asn1_template {
64 	const char	*name;
65 	const u8	*data;
66 	size_t		size;
67 } rsa_asn1_templates[] = {
68 #define _(X) { #X, rsa_digest_info_##X, sizeof(rsa_digest_info_##X) }
69 	_(md5),
70 	_(sha1),
71 	_(rmd160),
72 	_(sha256),
73 	_(sha384),
74 	_(sha512),
75 	_(sha224),
76 	{ NULL }
77 #undef _
78 };
79 
80 static const struct rsa_asn1_template *rsa_lookup_asn1(const char *name)
81 {
82 	const struct rsa_asn1_template *p;
83 
84 	for (p = rsa_asn1_templates; p->name; p++)
85 		if (strcmp(name, p->name) == 0)
86 			return p;
87 	return NULL;
88 }
89 
90 struct pkcs1pad_ctx {
91 	struct crypto_akcipher *child;
92 	unsigned int key_size;
93 };
94 
95 struct pkcs1pad_inst_ctx {
96 	struct crypto_akcipher_spawn spawn;
97 	const struct rsa_asn1_template *digest_info;
98 };
99 
100 struct pkcs1pad_request {
101 	struct scatterlist in_sg[2], out_sg[1];
102 	uint8_t *in_buf, *out_buf;
103 	struct akcipher_request child_req;
104 };
105 
106 static int pkcs1pad_set_pub_key(struct crypto_akcipher *tfm, const void *key,
107 		unsigned int keylen)
108 {
109 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
110 	int err;
111 
112 	ctx->key_size = 0;
113 
114 	err = crypto_akcipher_set_pub_key(ctx->child, key, keylen);
115 	if (err)
116 		return err;
117 
118 	/* Find out new modulus size from rsa implementation */
119 	err = crypto_akcipher_maxsize(ctx->child);
120 	if (err > PAGE_SIZE)
121 		return -ENOTSUPP;
122 
123 	ctx->key_size = err;
124 	return 0;
125 }
126 
127 static int pkcs1pad_set_priv_key(struct crypto_akcipher *tfm, const void *key,
128 		unsigned int keylen)
129 {
130 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
131 	int err;
132 
133 	ctx->key_size = 0;
134 
135 	err = crypto_akcipher_set_priv_key(ctx->child, key, keylen);
136 	if (err)
137 		return err;
138 
139 	/* Find out new modulus size from rsa implementation */
140 	err = crypto_akcipher_maxsize(ctx->child);
141 	if (err > PAGE_SIZE)
142 		return -ENOTSUPP;
143 
144 	ctx->key_size = err;
145 	return 0;
146 }
147 
148 static unsigned int pkcs1pad_get_max_size(struct crypto_akcipher *tfm)
149 {
150 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
151 
152 	/*
153 	 * The maximum destination buffer size for the encrypt/sign operations
154 	 * will be the same as for RSA, even though it's smaller for
155 	 * decrypt/verify.
156 	 */
157 
158 	return ctx->key_size;
159 }
160 
161 static void pkcs1pad_sg_set_buf(struct scatterlist *sg, void *buf, size_t len,
162 		struct scatterlist *next)
163 {
164 	int nsegs = next ? 2 : 1;
165 
166 	sg_init_table(sg, nsegs);
167 	sg_set_buf(sg, buf, len);
168 
169 	if (next)
170 		sg_chain(sg, nsegs, next);
171 }
172 
173 static int pkcs1pad_encrypt_sign_complete(struct akcipher_request *req, int err)
174 {
175 	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
176 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
177 	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
178 	unsigned int pad_len;
179 	unsigned int len;
180 	u8 *out_buf;
181 
182 	if (err)
183 		goto out;
184 
185 	len = req_ctx->child_req.dst_len;
186 	pad_len = ctx->key_size - len;
187 
188 	/* Four billion to one */
189 	if (likely(!pad_len))
190 		goto out;
191 
192 	out_buf = kzalloc(ctx->key_size, GFP_KERNEL);
193 	err = -ENOMEM;
194 	if (!out_buf)
195 		goto out;
196 
197 	sg_copy_to_buffer(req->dst, sg_nents_for_len(req->dst, len),
198 			  out_buf + pad_len, len);
199 	sg_copy_from_buffer(req->dst,
200 			    sg_nents_for_len(req->dst, ctx->key_size),
201 			    out_buf, ctx->key_size);
202 	kzfree(out_buf);
203 
204 out:
205 	req->dst_len = ctx->key_size;
206 
207 	kfree(req_ctx->in_buf);
208 
209 	return err;
210 }
211 
212 static void pkcs1pad_encrypt_sign_complete_cb(
213 		struct crypto_async_request *child_async_req, int err)
214 {
215 	struct akcipher_request *req = child_async_req->data;
216 	struct crypto_async_request async_req;
217 
218 	if (err == -EINPROGRESS)
219 		return;
220 
221 	async_req.data = req->base.data;
222 	async_req.tfm = crypto_akcipher_tfm(crypto_akcipher_reqtfm(req));
223 	async_req.flags = child_async_req->flags;
224 	req->base.complete(&async_req,
225 			pkcs1pad_encrypt_sign_complete(req, err));
226 }
227 
228 static int pkcs1pad_encrypt(struct akcipher_request *req)
229 {
230 	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
231 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
232 	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
233 	int err;
234 	unsigned int i, ps_end;
235 
236 	if (!ctx->key_size)
237 		return -EINVAL;
238 
239 	if (req->src_len > ctx->key_size - 11)
240 		return -EOVERFLOW;
241 
242 	if (req->dst_len < ctx->key_size) {
243 		req->dst_len = ctx->key_size;
244 		return -EOVERFLOW;
245 	}
246 
247 	req_ctx->in_buf = kmalloc(ctx->key_size - 1 - req->src_len,
248 				  GFP_KERNEL);
249 	if (!req_ctx->in_buf)
250 		return -ENOMEM;
251 
252 	ps_end = ctx->key_size - req->src_len - 2;
253 	req_ctx->in_buf[0] = 0x02;
254 	for (i = 1; i < ps_end; i++)
255 		req_ctx->in_buf[i] = 1 + prandom_u32_max(255);
256 	req_ctx->in_buf[ps_end] = 0x00;
257 
258 	pkcs1pad_sg_set_buf(req_ctx->in_sg, req_ctx->in_buf,
259 			ctx->key_size - 1 - req->src_len, req->src);
260 
261 	akcipher_request_set_tfm(&req_ctx->child_req, ctx->child);
262 	akcipher_request_set_callback(&req_ctx->child_req, req->base.flags,
263 			pkcs1pad_encrypt_sign_complete_cb, req);
264 
265 	/* Reuse output buffer */
266 	akcipher_request_set_crypt(&req_ctx->child_req, req_ctx->in_sg,
267 				   req->dst, ctx->key_size - 1, req->dst_len);
268 
269 	err = crypto_akcipher_encrypt(&req_ctx->child_req);
270 	if (err != -EINPROGRESS && err != -EBUSY)
271 		return pkcs1pad_encrypt_sign_complete(req, err);
272 
273 	return err;
274 }
275 
276 static int pkcs1pad_decrypt_complete(struct akcipher_request *req, int err)
277 {
278 	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
279 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
280 	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
281 	unsigned int dst_len;
282 	unsigned int pos;
283 	u8 *out_buf;
284 
285 	if (err)
286 		goto done;
287 
288 	err = -EINVAL;
289 	dst_len = req_ctx->child_req.dst_len;
290 	if (dst_len < ctx->key_size - 1)
291 		goto done;
292 
293 	out_buf = req_ctx->out_buf;
294 	if (dst_len == ctx->key_size) {
295 		if (out_buf[0] != 0x00)
296 			/* Decrypted value had no leading 0 byte */
297 			goto done;
298 
299 		dst_len--;
300 		out_buf++;
301 	}
302 
303 	if (out_buf[0] != 0x02)
304 		goto done;
305 
306 	for (pos = 1; pos < dst_len; pos++)
307 		if (out_buf[pos] == 0x00)
308 			break;
309 	if (pos < 9 || pos == dst_len)
310 		goto done;
311 	pos++;
312 
313 	err = 0;
314 
315 	if (req->dst_len < dst_len - pos)
316 		err = -EOVERFLOW;
317 	req->dst_len = dst_len - pos;
318 
319 	if (!err)
320 		sg_copy_from_buffer(req->dst,
321 				sg_nents_for_len(req->dst, req->dst_len),
322 				out_buf + pos, req->dst_len);
323 
324 done:
325 	kzfree(req_ctx->out_buf);
326 
327 	return err;
328 }
329 
330 static void pkcs1pad_decrypt_complete_cb(
331 		struct crypto_async_request *child_async_req, int err)
332 {
333 	struct akcipher_request *req = child_async_req->data;
334 	struct crypto_async_request async_req;
335 
336 	if (err == -EINPROGRESS)
337 		return;
338 
339 	async_req.data = req->base.data;
340 	async_req.tfm = crypto_akcipher_tfm(crypto_akcipher_reqtfm(req));
341 	async_req.flags = child_async_req->flags;
342 	req->base.complete(&async_req, pkcs1pad_decrypt_complete(req, err));
343 }
344 
345 static int pkcs1pad_decrypt(struct akcipher_request *req)
346 {
347 	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
348 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
349 	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
350 	int err;
351 
352 	if (!ctx->key_size || req->src_len != ctx->key_size)
353 		return -EINVAL;
354 
355 	req_ctx->out_buf = kmalloc(ctx->key_size, GFP_KERNEL);
356 	if (!req_ctx->out_buf)
357 		return -ENOMEM;
358 
359 	pkcs1pad_sg_set_buf(req_ctx->out_sg, req_ctx->out_buf,
360 			    ctx->key_size, NULL);
361 
362 	akcipher_request_set_tfm(&req_ctx->child_req, ctx->child);
363 	akcipher_request_set_callback(&req_ctx->child_req, req->base.flags,
364 			pkcs1pad_decrypt_complete_cb, req);
365 
366 	/* Reuse input buffer, output to a new buffer */
367 	akcipher_request_set_crypt(&req_ctx->child_req, req->src,
368 				   req_ctx->out_sg, req->src_len,
369 				   ctx->key_size);
370 
371 	err = crypto_akcipher_decrypt(&req_ctx->child_req);
372 	if (err != -EINPROGRESS && err != -EBUSY)
373 		return pkcs1pad_decrypt_complete(req, err);
374 
375 	return err;
376 }
377 
378 static int pkcs1pad_sign(struct akcipher_request *req)
379 {
380 	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
381 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
382 	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
383 	struct akcipher_instance *inst = akcipher_alg_instance(tfm);
384 	struct pkcs1pad_inst_ctx *ictx = akcipher_instance_ctx(inst);
385 	const struct rsa_asn1_template *digest_info = ictx->digest_info;
386 	int err;
387 	unsigned int ps_end, digest_size = 0;
388 
389 	if (!ctx->key_size)
390 		return -EINVAL;
391 
392 	if (digest_info)
393 		digest_size = digest_info->size;
394 
395 	if (req->src_len + digest_size > ctx->key_size - 11)
396 		return -EOVERFLOW;
397 
398 	if (req->dst_len < ctx->key_size) {
399 		req->dst_len = ctx->key_size;
400 		return -EOVERFLOW;
401 	}
402 
403 	req_ctx->in_buf = kmalloc(ctx->key_size - 1 - req->src_len,
404 				  GFP_KERNEL);
405 	if (!req_ctx->in_buf)
406 		return -ENOMEM;
407 
408 	ps_end = ctx->key_size - digest_size - req->src_len - 2;
409 	req_ctx->in_buf[0] = 0x01;
410 	memset(req_ctx->in_buf + 1, 0xff, ps_end - 1);
411 	req_ctx->in_buf[ps_end] = 0x00;
412 
413 	if (digest_info)
414 		memcpy(req_ctx->in_buf + ps_end + 1, digest_info->data,
415 		       digest_info->size);
416 
417 	pkcs1pad_sg_set_buf(req_ctx->in_sg, req_ctx->in_buf,
418 			ctx->key_size - 1 - req->src_len, req->src);
419 
420 	akcipher_request_set_tfm(&req_ctx->child_req, ctx->child);
421 	akcipher_request_set_callback(&req_ctx->child_req, req->base.flags,
422 			pkcs1pad_encrypt_sign_complete_cb, req);
423 
424 	/* Reuse output buffer */
425 	akcipher_request_set_crypt(&req_ctx->child_req, req_ctx->in_sg,
426 				   req->dst, ctx->key_size - 1, req->dst_len);
427 
428 	err = crypto_akcipher_decrypt(&req_ctx->child_req);
429 	if (err != -EINPROGRESS && err != -EBUSY)
430 		return pkcs1pad_encrypt_sign_complete(req, err);
431 
432 	return err;
433 }
434 
435 static int pkcs1pad_verify_complete(struct akcipher_request *req, int err)
436 {
437 	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
438 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
439 	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
440 	struct akcipher_instance *inst = akcipher_alg_instance(tfm);
441 	struct pkcs1pad_inst_ctx *ictx = akcipher_instance_ctx(inst);
442 	const struct rsa_asn1_template *digest_info = ictx->digest_info;
443 	unsigned int dst_len;
444 	unsigned int pos;
445 	u8 *out_buf;
446 
447 	if (err)
448 		goto done;
449 
450 	err = -EINVAL;
451 	dst_len = req_ctx->child_req.dst_len;
452 	if (dst_len < ctx->key_size - 1)
453 		goto done;
454 
455 	out_buf = req_ctx->out_buf;
456 	if (dst_len == ctx->key_size) {
457 		if (out_buf[0] != 0x00)
458 			/* Decrypted value had no leading 0 byte */
459 			goto done;
460 
461 		dst_len--;
462 		out_buf++;
463 	}
464 
465 	err = -EBADMSG;
466 	if (out_buf[0] != 0x01)
467 		goto done;
468 
469 	for (pos = 1; pos < dst_len; pos++)
470 		if (out_buf[pos] != 0xff)
471 			break;
472 
473 	if (pos < 9 || pos == dst_len || out_buf[pos] != 0x00)
474 		goto done;
475 	pos++;
476 
477 	if (digest_info) {
478 		if (crypto_memneq(out_buf + pos, digest_info->data,
479 				  digest_info->size))
480 			goto done;
481 
482 		pos += digest_info->size;
483 	}
484 
485 	err = 0;
486 
487 	if (req->dst_len != dst_len - pos) {
488 		err = -EKEYREJECTED;
489 		req->dst_len = dst_len - pos;
490 		goto done;
491 	}
492 	/* Extract appended digest. */
493 	sg_pcopy_to_buffer(req->src,
494 			   sg_nents_for_len(req->src,
495 					    req->src_len + req->dst_len),
496 			   req_ctx->out_buf + ctx->key_size,
497 			   req->dst_len, ctx->key_size);
498 	/* Do the actual verification step. */
499 	if (memcmp(req_ctx->out_buf + ctx->key_size, out_buf + pos,
500 		   req->dst_len) != 0)
501 		err = -EKEYREJECTED;
502 done:
503 	kzfree(req_ctx->out_buf);
504 
505 	return err;
506 }
507 
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  */
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 (WARN_ON(req->dst) ||
539 	    WARN_ON(!req->dst_len) ||
540 	    !ctx->key_size || req->src_len < ctx->key_size)
541 		return -EINVAL;
542 
543 	req_ctx->out_buf = kmalloc(ctx->key_size + req->dst_len, GFP_KERNEL);
544 	if (!req_ctx->out_buf)
545 		return -ENOMEM;
546 
547 	pkcs1pad_sg_set_buf(req_ctx->out_sg, req_ctx->out_buf,
548 			    ctx->key_size, NULL);
549 
550 	akcipher_request_set_tfm(&req_ctx->child_req, ctx->child);
551 	akcipher_request_set_callback(&req_ctx->child_req, req->base.flags,
552 			pkcs1pad_verify_complete_cb, req);
553 
554 	/* Reuse input buffer, output to a new buffer */
555 	akcipher_request_set_crypt(&req_ctx->child_req, req->src,
556 				   req_ctx->out_sg, req->src_len,
557 				   ctx->key_size);
558 
559 	err = crypto_akcipher_encrypt(&req_ctx->child_req);
560 	if (err != -EINPROGRESS && err != -EBUSY)
561 		return pkcs1pad_verify_complete(req, err);
562 
563 	return err;
564 }
565 
566 static int pkcs1pad_init_tfm(struct crypto_akcipher *tfm)
567 {
568 	struct akcipher_instance *inst = akcipher_alg_instance(tfm);
569 	struct pkcs1pad_inst_ctx *ictx = akcipher_instance_ctx(inst);
570 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
571 	struct crypto_akcipher *child_tfm;
572 
573 	child_tfm = crypto_spawn_akcipher(&ictx->spawn);
574 	if (IS_ERR(child_tfm))
575 		return PTR_ERR(child_tfm);
576 
577 	ctx->child = child_tfm;
578 	return 0;
579 }
580 
581 static void pkcs1pad_exit_tfm(struct crypto_akcipher *tfm)
582 {
583 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
584 
585 	crypto_free_akcipher(ctx->child);
586 }
587 
588 static void pkcs1pad_free(struct akcipher_instance *inst)
589 {
590 	struct pkcs1pad_inst_ctx *ctx = akcipher_instance_ctx(inst);
591 	struct crypto_akcipher_spawn *spawn = &ctx->spawn;
592 
593 	crypto_drop_akcipher(spawn);
594 	kfree(inst);
595 }
596 
597 static int pkcs1pad_create(struct crypto_template *tmpl, struct rtattr **tb)
598 {
599 	const struct rsa_asn1_template *digest_info;
600 	struct crypto_attr_type *algt;
601 	u32 mask;
602 	struct akcipher_instance *inst;
603 	struct pkcs1pad_inst_ctx *ctx;
604 	struct crypto_akcipher_spawn *spawn;
605 	struct akcipher_alg *rsa_alg;
606 	const char *rsa_alg_name;
607 	const char *hash_name;
608 	int err;
609 
610 	algt = crypto_get_attr_type(tb);
611 	if (IS_ERR(algt))
612 		return PTR_ERR(algt);
613 
614 	if ((algt->type ^ CRYPTO_ALG_TYPE_AKCIPHER) & algt->mask)
615 		return -EINVAL;
616 
617 	mask = crypto_requires_sync(algt->type, algt->mask);
618 
619 	rsa_alg_name = crypto_attr_alg_name(tb[1]);
620 	if (IS_ERR(rsa_alg_name))
621 		return PTR_ERR(rsa_alg_name);
622 
623 	hash_name = crypto_attr_alg_name(tb[2]);
624 	if (IS_ERR(hash_name))
625 		hash_name = NULL;
626 
627 	if (hash_name) {
628 		digest_info = rsa_lookup_asn1(hash_name);
629 		if (!digest_info)
630 			return -EINVAL;
631 	} else
632 		digest_info = NULL;
633 
634 	inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
635 	if (!inst)
636 		return -ENOMEM;
637 
638 	ctx = akcipher_instance_ctx(inst);
639 	spawn = &ctx->spawn;
640 	ctx->digest_info = digest_info;
641 
642 	err = crypto_grab_akcipher(spawn, akcipher_crypto_instance(inst),
643 				   rsa_alg_name, 0, mask);
644 	if (err)
645 		goto out_free_inst;
646 
647 	rsa_alg = crypto_spawn_akcipher_alg(spawn);
648 
649 	err = -ENAMETOOLONG;
650 
651 	if (!hash_name) {
652 		if (snprintf(inst->alg.base.cra_name,
653 			     CRYPTO_MAX_ALG_NAME, "pkcs1pad(%s)",
654 			     rsa_alg->base.cra_name) >= CRYPTO_MAX_ALG_NAME)
655 			goto out_drop_alg;
656 
657 		if (snprintf(inst->alg.base.cra_driver_name,
658 			     CRYPTO_MAX_ALG_NAME, "pkcs1pad(%s)",
659 			     rsa_alg->base.cra_driver_name) >=
660 			     CRYPTO_MAX_ALG_NAME)
661 			goto out_drop_alg;
662 	} else {
663 		if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
664 			     "pkcs1pad(%s,%s)", rsa_alg->base.cra_name,
665 			     hash_name) >= CRYPTO_MAX_ALG_NAME)
666 			goto out_drop_alg;
667 
668 		if (snprintf(inst->alg.base.cra_driver_name,
669 			     CRYPTO_MAX_ALG_NAME, "pkcs1pad(%s,%s)",
670 			     rsa_alg->base.cra_driver_name,
671 			     hash_name) >= CRYPTO_MAX_ALG_NAME)
672 			goto out_drop_alg;
673 	}
674 
675 	inst->alg.base.cra_flags = rsa_alg->base.cra_flags & CRYPTO_ALG_ASYNC;
676 	inst->alg.base.cra_priority = rsa_alg->base.cra_priority;
677 	inst->alg.base.cra_ctxsize = sizeof(struct pkcs1pad_ctx);
678 
679 	inst->alg.init = pkcs1pad_init_tfm;
680 	inst->alg.exit = pkcs1pad_exit_tfm;
681 
682 	inst->alg.encrypt = pkcs1pad_encrypt;
683 	inst->alg.decrypt = pkcs1pad_decrypt;
684 	inst->alg.sign = pkcs1pad_sign;
685 	inst->alg.verify = pkcs1pad_verify;
686 	inst->alg.set_pub_key = pkcs1pad_set_pub_key;
687 	inst->alg.set_priv_key = pkcs1pad_set_priv_key;
688 	inst->alg.max_size = pkcs1pad_get_max_size;
689 	inst->alg.reqsize = sizeof(struct pkcs1pad_request) + rsa_alg->reqsize;
690 
691 	inst->free = pkcs1pad_free;
692 
693 	err = akcipher_register_instance(tmpl, inst);
694 	if (err)
695 		goto out_drop_alg;
696 
697 	return 0;
698 
699 out_drop_alg:
700 	crypto_drop_akcipher(spawn);
701 out_free_inst:
702 	kfree(inst);
703 	return err;
704 }
705 
706 struct crypto_template rsa_pkcs1pad_tmpl = {
707 	.name = "pkcs1pad",
708 	.create = pkcs1pad_create,
709 	.module = THIS_MODULE,
710 };
711