xref: /linux/crypto/rsa-pkcs1pad.c (revision 40d269c000bda9fcd276a0412a9cebd3f6e344c5)
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 #include <linux/scatterlist.h>
18 
19 /*
20  * Hash algorithm OIDs plus ASN.1 DER wrappings [RFC4880 sec 5.2.2].
21  */
22 static const u8 rsa_digest_info_md5[] = {
23 	0x30, 0x20, 0x30, 0x0c, 0x06, 0x08,
24 	0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d, 0x02, 0x05, /* OID */
25 	0x05, 0x00, 0x04, 0x10
26 };
27 
28 static const u8 rsa_digest_info_sha1[] = {
29 	0x30, 0x21, 0x30, 0x09, 0x06, 0x05,
30 	0x2b, 0x0e, 0x03, 0x02, 0x1a,
31 	0x05, 0x00, 0x04, 0x14
32 };
33 
34 static const u8 rsa_digest_info_rmd160[] = {
35 	0x30, 0x21, 0x30, 0x09, 0x06, 0x05,
36 	0x2b, 0x24, 0x03, 0x02, 0x01,
37 	0x05, 0x00, 0x04, 0x14
38 };
39 
40 static const u8 rsa_digest_info_sha224[] = {
41 	0x30, 0x2d, 0x30, 0x0d, 0x06, 0x09,
42 	0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x04,
43 	0x05, 0x00, 0x04, 0x1c
44 };
45 
46 static const u8 rsa_digest_info_sha256[] = {
47 	0x30, 0x31, 0x30, 0x0d, 0x06, 0x09,
48 	0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x01,
49 	0x05, 0x00, 0x04, 0x20
50 };
51 
52 static const u8 rsa_digest_info_sha384[] = {
53 	0x30, 0x41, 0x30, 0x0d, 0x06, 0x09,
54 	0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x02,
55 	0x05, 0x00, 0x04, 0x30
56 };
57 
58 static const u8 rsa_digest_info_sha512[] = {
59 	0x30, 0x51, 0x30, 0x0d, 0x06, 0x09,
60 	0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x03,
61 	0x05, 0x00, 0x04, 0x40
62 };
63 
64 static const u8 rsa_digest_info_sha3_256[] = {
65 	0x30, 0x31, 0x30, 0x0d, 0x06, 0x09,
66 	0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x08,
67 	0x05, 0x00, 0x04, 0x20
68 };
69 
70 static const u8 rsa_digest_info_sha3_384[] = {
71 	0x30, 0x41, 0x30, 0x0d, 0x06, 0x09,
72 	0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x09,
73 	0x05, 0x00, 0x04, 0x30
74 };
75 
76 static const u8 rsa_digest_info_sha3_512[] = {
77 	0x30, 0x51, 0x30, 0x0d, 0x06, 0x09,
78 	0x60, 0x86, 0x48, 0x01, 0x65, 0x03, 0x04, 0x02, 0x0A,
79 	0x05, 0x00, 0x04, 0x40
80 };
81 
82 static const struct rsa_asn1_template {
83 	const char	*name;
84 	const u8	*data;
85 	size_t		size;
86 } rsa_asn1_templates[] = {
87 #define _(X) { #X, rsa_digest_info_##X, sizeof(rsa_digest_info_##X) }
88 	_(md5),
89 	_(sha1),
90 	_(rmd160),
91 	_(sha256),
92 	_(sha384),
93 	_(sha512),
94 	_(sha224),
95 #undef _
96 #define _(X) { "sha3-" #X, rsa_digest_info_sha3_##X, sizeof(rsa_digest_info_sha3_##X) }
97 	_(256),
98 	_(384),
99 	_(512),
100 #undef _
101 	{ NULL }
102 };
103 
104 static const struct rsa_asn1_template *rsa_lookup_asn1(const char *name)
105 {
106 	const struct rsa_asn1_template *p;
107 
108 	for (p = rsa_asn1_templates; p->name; p++)
109 		if (strcmp(name, p->name) == 0)
110 			return p;
111 	return NULL;
112 }
113 
114 struct pkcs1pad_ctx {
115 	struct crypto_akcipher *child;
116 	unsigned int key_size;
117 };
118 
119 struct pkcs1pad_inst_ctx {
120 	struct crypto_akcipher_spawn spawn;
121 	const struct rsa_asn1_template *digest_info;
122 };
123 
124 struct pkcs1pad_request {
125 	struct scatterlist in_sg[2], out_sg[1];
126 	uint8_t *in_buf, *out_buf;
127 	struct akcipher_request child_req;
128 };
129 
130 static int pkcs1pad_set_pub_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_pub_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 int pkcs1pad_set_priv_key(struct crypto_akcipher *tfm, const void *key,
152 		unsigned int keylen)
153 {
154 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
155 	int err;
156 
157 	ctx->key_size = 0;
158 
159 	err = crypto_akcipher_set_priv_key(ctx->child, key, keylen);
160 	if (err)
161 		return err;
162 
163 	/* Find out new modulus size from rsa implementation */
164 	err = crypto_akcipher_maxsize(ctx->child);
165 	if (err > PAGE_SIZE)
166 		return -ENOTSUPP;
167 
168 	ctx->key_size = err;
169 	return 0;
170 }
171 
172 static unsigned int pkcs1pad_get_max_size(struct crypto_akcipher *tfm)
173 {
174 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
175 
176 	/*
177 	 * The maximum destination buffer size for the encrypt/sign operations
178 	 * will be the same as for RSA, even though it's smaller for
179 	 * decrypt/verify.
180 	 */
181 
182 	return ctx->key_size;
183 }
184 
185 static void pkcs1pad_sg_set_buf(struct scatterlist *sg, void *buf, size_t len,
186 		struct scatterlist *next)
187 {
188 	int nsegs = next ? 2 : 1;
189 
190 	sg_init_table(sg, nsegs);
191 	sg_set_buf(sg, buf, len);
192 
193 	if (next)
194 		sg_chain(sg, nsegs, next);
195 }
196 
197 static int pkcs1pad_encrypt_sign_complete(struct akcipher_request *req, int err)
198 {
199 	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
200 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
201 	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
202 	unsigned int pad_len;
203 	unsigned int len;
204 	u8 *out_buf;
205 
206 	if (err)
207 		goto out;
208 
209 	len = req_ctx->child_req.dst_len;
210 	pad_len = ctx->key_size - len;
211 
212 	/* Four billion to one */
213 	if (likely(!pad_len))
214 		goto out;
215 
216 	out_buf = kzalloc(ctx->key_size, GFP_ATOMIC);
217 	err = -ENOMEM;
218 	if (!out_buf)
219 		goto out;
220 
221 	sg_copy_to_buffer(req->dst, sg_nents_for_len(req->dst, len),
222 			  out_buf + pad_len, len);
223 	sg_copy_from_buffer(req->dst,
224 			    sg_nents_for_len(req->dst, ctx->key_size),
225 			    out_buf, ctx->key_size);
226 	kfree_sensitive(out_buf);
227 
228 out:
229 	req->dst_len = ctx->key_size;
230 
231 	kfree(req_ctx->in_buf);
232 
233 	return err;
234 }
235 
236 static void pkcs1pad_encrypt_sign_complete_cb(void *data, int err)
237 {
238 	struct akcipher_request *req = data;
239 
240 	if (err == -EINPROGRESS)
241 		goto out;
242 
243 	err = pkcs1pad_encrypt_sign_complete(req, err);
244 
245 out:
246 	akcipher_request_complete(req, err);
247 }
248 
249 static int pkcs1pad_encrypt(struct akcipher_request *req)
250 {
251 	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
252 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
253 	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
254 	int err;
255 	unsigned int i, ps_end;
256 
257 	if (!ctx->key_size)
258 		return -EINVAL;
259 
260 	if (req->src_len > ctx->key_size - 11)
261 		return -EOVERFLOW;
262 
263 	if (req->dst_len < ctx->key_size) {
264 		req->dst_len = ctx->key_size;
265 		return -EOVERFLOW;
266 	}
267 
268 	req_ctx->in_buf = kmalloc(ctx->key_size - 1 - req->src_len,
269 				  GFP_KERNEL);
270 	if (!req_ctx->in_buf)
271 		return -ENOMEM;
272 
273 	ps_end = ctx->key_size - req->src_len - 2;
274 	req_ctx->in_buf[0] = 0x02;
275 	for (i = 1; i < ps_end; i++)
276 		req_ctx->in_buf[i] = get_random_u32_inclusive(1, 255);
277 	req_ctx->in_buf[ps_end] = 0x00;
278 
279 	pkcs1pad_sg_set_buf(req_ctx->in_sg, req_ctx->in_buf,
280 			ctx->key_size - 1 - req->src_len, req->src);
281 
282 	akcipher_request_set_tfm(&req_ctx->child_req, ctx->child);
283 	akcipher_request_set_callback(&req_ctx->child_req, req->base.flags,
284 			pkcs1pad_encrypt_sign_complete_cb, req);
285 
286 	/* Reuse output buffer */
287 	akcipher_request_set_crypt(&req_ctx->child_req, req_ctx->in_sg,
288 				   req->dst, ctx->key_size - 1, req->dst_len);
289 
290 	err = crypto_akcipher_encrypt(&req_ctx->child_req);
291 	if (err != -EINPROGRESS && err != -EBUSY)
292 		return pkcs1pad_encrypt_sign_complete(req, err);
293 
294 	return err;
295 }
296 
297 static int pkcs1pad_decrypt_complete(struct akcipher_request *req, int err)
298 {
299 	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
300 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
301 	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
302 	unsigned int dst_len;
303 	unsigned int pos;
304 	u8 *out_buf;
305 
306 	if (err)
307 		goto done;
308 
309 	err = -EINVAL;
310 	dst_len = req_ctx->child_req.dst_len;
311 	if (dst_len < ctx->key_size - 1)
312 		goto done;
313 
314 	out_buf = req_ctx->out_buf;
315 	if (dst_len == ctx->key_size) {
316 		if (out_buf[0] != 0x00)
317 			/* Decrypted value had no leading 0 byte */
318 			goto done;
319 
320 		dst_len--;
321 		out_buf++;
322 	}
323 
324 	if (out_buf[0] != 0x02)
325 		goto done;
326 
327 	for (pos = 1; pos < dst_len; pos++)
328 		if (out_buf[pos] == 0x00)
329 			break;
330 	if (pos < 9 || pos == dst_len)
331 		goto done;
332 	pos++;
333 
334 	err = 0;
335 
336 	if (req->dst_len < dst_len - pos)
337 		err = -EOVERFLOW;
338 	req->dst_len = dst_len - pos;
339 
340 	if (!err)
341 		sg_copy_from_buffer(req->dst,
342 				sg_nents_for_len(req->dst, req->dst_len),
343 				out_buf + pos, req->dst_len);
344 
345 done:
346 	kfree_sensitive(req_ctx->out_buf);
347 
348 	return err;
349 }
350 
351 static void pkcs1pad_decrypt_complete_cb(void *data, int err)
352 {
353 	struct akcipher_request *req = data;
354 
355 	if (err == -EINPROGRESS)
356 		goto out;
357 
358 	err = pkcs1pad_decrypt_complete(req, err);
359 
360 out:
361 	akcipher_request_complete(req, err);
362 }
363 
364 static int pkcs1pad_decrypt(struct akcipher_request *req)
365 {
366 	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
367 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
368 	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
369 	int err;
370 
371 	if (!ctx->key_size || req->src_len != ctx->key_size)
372 		return -EINVAL;
373 
374 	req_ctx->out_buf = kmalloc(ctx->key_size, GFP_KERNEL);
375 	if (!req_ctx->out_buf)
376 		return -ENOMEM;
377 
378 	pkcs1pad_sg_set_buf(req_ctx->out_sg, req_ctx->out_buf,
379 			    ctx->key_size, NULL);
380 
381 	akcipher_request_set_tfm(&req_ctx->child_req, ctx->child);
382 	akcipher_request_set_callback(&req_ctx->child_req, req->base.flags,
383 			pkcs1pad_decrypt_complete_cb, req);
384 
385 	/* Reuse input buffer, output to a new buffer */
386 	akcipher_request_set_crypt(&req_ctx->child_req, req->src,
387 				   req_ctx->out_sg, req->src_len,
388 				   ctx->key_size);
389 
390 	err = crypto_akcipher_decrypt(&req_ctx->child_req);
391 	if (err != -EINPROGRESS && err != -EBUSY)
392 		return pkcs1pad_decrypt_complete(req, err);
393 
394 	return err;
395 }
396 
397 static int pkcs1pad_sign(struct akcipher_request *req)
398 {
399 	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
400 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
401 	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
402 	struct akcipher_instance *inst = akcipher_alg_instance(tfm);
403 	struct pkcs1pad_inst_ctx *ictx = akcipher_instance_ctx(inst);
404 	const struct rsa_asn1_template *digest_info = ictx->digest_info;
405 	int err;
406 	unsigned int ps_end, digest_info_size = 0;
407 
408 	if (!ctx->key_size)
409 		return -EINVAL;
410 
411 	if (digest_info)
412 		digest_info_size = digest_info->size;
413 
414 	if (req->src_len + digest_info_size > ctx->key_size - 11)
415 		return -EOVERFLOW;
416 
417 	if (req->dst_len < ctx->key_size) {
418 		req->dst_len = ctx->key_size;
419 		return -EOVERFLOW;
420 	}
421 
422 	req_ctx->in_buf = kmalloc(ctx->key_size - 1 - req->src_len,
423 				  GFP_KERNEL);
424 	if (!req_ctx->in_buf)
425 		return -ENOMEM;
426 
427 	ps_end = ctx->key_size - digest_info_size - req->src_len - 2;
428 	req_ctx->in_buf[0] = 0x01;
429 	memset(req_ctx->in_buf + 1, 0xff, ps_end - 1);
430 	req_ctx->in_buf[ps_end] = 0x00;
431 
432 	if (digest_info)
433 		memcpy(req_ctx->in_buf + ps_end + 1, digest_info->data,
434 		       digest_info->size);
435 
436 	pkcs1pad_sg_set_buf(req_ctx->in_sg, req_ctx->in_buf,
437 			ctx->key_size - 1 - req->src_len, req->src);
438 
439 	akcipher_request_set_tfm(&req_ctx->child_req, ctx->child);
440 	akcipher_request_set_callback(&req_ctx->child_req, req->base.flags,
441 			pkcs1pad_encrypt_sign_complete_cb, req);
442 
443 	/* Reuse output buffer */
444 	akcipher_request_set_crypt(&req_ctx->child_req, req_ctx->in_sg,
445 				   req->dst, ctx->key_size - 1, req->dst_len);
446 
447 	err = crypto_akcipher_decrypt(&req_ctx->child_req);
448 	if (err != -EINPROGRESS && err != -EBUSY)
449 		return pkcs1pad_encrypt_sign_complete(req, err);
450 
451 	return err;
452 }
453 
454 static int pkcs1pad_verify_complete(struct akcipher_request *req, int err)
455 {
456 	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
457 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
458 	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
459 	struct akcipher_instance *inst = akcipher_alg_instance(tfm);
460 	struct pkcs1pad_inst_ctx *ictx = akcipher_instance_ctx(inst);
461 	const struct rsa_asn1_template *digest_info = ictx->digest_info;
462 	const unsigned int sig_size = req->src_len;
463 	const unsigned int digest_size = req->dst_len;
464 	unsigned int dst_len;
465 	unsigned int pos;
466 	u8 *out_buf;
467 
468 	if (err)
469 		goto done;
470 
471 	err = -EINVAL;
472 	dst_len = req_ctx->child_req.dst_len;
473 	if (dst_len < ctx->key_size - 1)
474 		goto done;
475 
476 	out_buf = req_ctx->out_buf;
477 	if (dst_len == ctx->key_size) {
478 		if (out_buf[0] != 0x00)
479 			/* Decrypted value had no leading 0 byte */
480 			goto done;
481 
482 		dst_len--;
483 		out_buf++;
484 	}
485 
486 	err = -EBADMSG;
487 	if (out_buf[0] != 0x01)
488 		goto done;
489 
490 	for (pos = 1; pos < dst_len; pos++)
491 		if (out_buf[pos] != 0xff)
492 			break;
493 
494 	if (pos < 9 || pos == dst_len || out_buf[pos] != 0x00)
495 		goto done;
496 	pos++;
497 
498 	if (digest_info) {
499 		if (digest_info->size > dst_len - pos)
500 			goto done;
501 		if (crypto_memneq(out_buf + pos, digest_info->data,
502 				  digest_info->size))
503 			goto done;
504 
505 		pos += digest_info->size;
506 	}
507 
508 	err = 0;
509 
510 	if (digest_size != dst_len - pos) {
511 		err = -EKEYREJECTED;
512 		req->dst_len = dst_len - pos;
513 		goto done;
514 	}
515 	/* Extract appended digest. */
516 	sg_pcopy_to_buffer(req->src,
517 			   sg_nents_for_len(req->src, sig_size + digest_size),
518 			   req_ctx->out_buf + ctx->key_size,
519 			   digest_size, sig_size);
520 	/* Do the actual verification step. */
521 	if (memcmp(req_ctx->out_buf + ctx->key_size, out_buf + pos,
522 		   digest_size) != 0)
523 		err = -EKEYREJECTED;
524 done:
525 	kfree_sensitive(req_ctx->out_buf);
526 
527 	return err;
528 }
529 
530 static void pkcs1pad_verify_complete_cb(void *data, int err)
531 {
532 	struct akcipher_request *req = data;
533 
534 	if (err == -EINPROGRESS)
535 		goto out;
536 
537 	err = pkcs1pad_verify_complete(req, err);
538 
539 out:
540 	akcipher_request_complete(req, err);
541 }
542 
543 /*
544  * The verify operation is here for completeness similar to the verification
545  * defined in RFC2313 section 10.2 except that block type 0 is not accepted,
546  * as in RFC2437.  RFC2437 section 9.2 doesn't define any operation to
547  * retrieve the DigestInfo from a signature, instead the user is expected
548  * to call the sign operation to generate the expected signature and compare
549  * signatures instead of the message-digests.
550  */
551 static int pkcs1pad_verify(struct akcipher_request *req)
552 {
553 	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
554 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
555 	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
556 	const unsigned int sig_size = req->src_len;
557 	const unsigned int digest_size = req->dst_len;
558 	int err;
559 
560 	if (WARN_ON(req->dst) || WARN_ON(!digest_size) ||
561 	    !ctx->key_size || sig_size != ctx->key_size)
562 		return -EINVAL;
563 
564 	req_ctx->out_buf = kmalloc(ctx->key_size + digest_size, GFP_KERNEL);
565 	if (!req_ctx->out_buf)
566 		return -ENOMEM;
567 
568 	pkcs1pad_sg_set_buf(req_ctx->out_sg, req_ctx->out_buf,
569 			    ctx->key_size, NULL);
570 
571 	akcipher_request_set_tfm(&req_ctx->child_req, ctx->child);
572 	akcipher_request_set_callback(&req_ctx->child_req, req->base.flags,
573 			pkcs1pad_verify_complete_cb, req);
574 
575 	/* Reuse input buffer, output to a new buffer */
576 	akcipher_request_set_crypt(&req_ctx->child_req, req->src,
577 				   req_ctx->out_sg, sig_size, ctx->key_size);
578 
579 	err = crypto_akcipher_encrypt(&req_ctx->child_req);
580 	if (err != -EINPROGRESS && err != -EBUSY)
581 		return pkcs1pad_verify_complete(req, err);
582 
583 	return err;
584 }
585 
586 static int pkcs1pad_init_tfm(struct crypto_akcipher *tfm)
587 {
588 	struct akcipher_instance *inst = akcipher_alg_instance(tfm);
589 	struct pkcs1pad_inst_ctx *ictx = akcipher_instance_ctx(inst);
590 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
591 	struct crypto_akcipher *child_tfm;
592 
593 	child_tfm = crypto_spawn_akcipher(&ictx->spawn);
594 	if (IS_ERR(child_tfm))
595 		return PTR_ERR(child_tfm);
596 
597 	ctx->child = child_tfm;
598 
599 	akcipher_set_reqsize(tfm, sizeof(struct pkcs1pad_request) +
600 				  crypto_akcipher_reqsize(child_tfm));
601 
602 	return 0;
603 }
604 
605 static void pkcs1pad_exit_tfm(struct crypto_akcipher *tfm)
606 {
607 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
608 
609 	crypto_free_akcipher(ctx->child);
610 }
611 
612 static void pkcs1pad_free(struct akcipher_instance *inst)
613 {
614 	struct pkcs1pad_inst_ctx *ctx = akcipher_instance_ctx(inst);
615 	struct crypto_akcipher_spawn *spawn = &ctx->spawn;
616 
617 	crypto_drop_akcipher(spawn);
618 	kfree(inst);
619 }
620 
621 static int pkcs1pad_create(struct crypto_template *tmpl, struct rtattr **tb)
622 {
623 	u32 mask;
624 	struct akcipher_instance *inst;
625 	struct pkcs1pad_inst_ctx *ctx;
626 	struct akcipher_alg *rsa_alg;
627 	const char *hash_name;
628 	int err;
629 
630 	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_AKCIPHER, &mask);
631 	if (err)
632 		return err;
633 
634 	inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
635 	if (!inst)
636 		return -ENOMEM;
637 
638 	ctx = akcipher_instance_ctx(inst);
639 
640 	err = crypto_grab_akcipher(&ctx->spawn, akcipher_crypto_instance(inst),
641 				   crypto_attr_alg_name(tb[1]), 0, mask);
642 	if (err)
643 		goto err_free_inst;
644 
645 	rsa_alg = crypto_spawn_akcipher_alg(&ctx->spawn);
646 
647 	if (strcmp(rsa_alg->base.cra_name, "rsa") != 0) {
648 		err = -EINVAL;
649 		goto err_free_inst;
650 	}
651 
652 	err = -ENAMETOOLONG;
653 	hash_name = crypto_attr_alg_name(tb[2]);
654 	if (IS_ERR(hash_name)) {
655 		if (snprintf(inst->alg.base.cra_name,
656 			     CRYPTO_MAX_ALG_NAME, "pkcs1pad(%s)",
657 			     rsa_alg->base.cra_name) >= CRYPTO_MAX_ALG_NAME)
658 			goto err_free_inst;
659 
660 		if (snprintf(inst->alg.base.cra_driver_name,
661 			     CRYPTO_MAX_ALG_NAME, "pkcs1pad(%s)",
662 			     rsa_alg->base.cra_driver_name) >=
663 			     CRYPTO_MAX_ALG_NAME)
664 			goto err_free_inst;
665 	} else {
666 		ctx->digest_info = rsa_lookup_asn1(hash_name);
667 		if (!ctx->digest_info) {
668 			err = -EINVAL;
669 			goto err_free_inst;
670 		}
671 
672 		if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
673 			     "pkcs1pad(%s,%s)", rsa_alg->base.cra_name,
674 			     hash_name) >= CRYPTO_MAX_ALG_NAME)
675 			goto err_free_inst;
676 
677 		if (snprintf(inst->alg.base.cra_driver_name,
678 			     CRYPTO_MAX_ALG_NAME, "pkcs1pad(%s,%s)",
679 			     rsa_alg->base.cra_driver_name,
680 			     hash_name) >= CRYPTO_MAX_ALG_NAME)
681 			goto err_free_inst;
682 	}
683 
684 	inst->alg.base.cra_priority = rsa_alg->base.cra_priority;
685 	inst->alg.base.cra_ctxsize = sizeof(struct pkcs1pad_ctx);
686 
687 	inst->alg.init = pkcs1pad_init_tfm;
688 	inst->alg.exit = pkcs1pad_exit_tfm;
689 
690 	inst->alg.encrypt = pkcs1pad_encrypt;
691 	inst->alg.decrypt = pkcs1pad_decrypt;
692 	inst->alg.sign = pkcs1pad_sign;
693 	inst->alg.verify = pkcs1pad_verify;
694 	inst->alg.set_pub_key = pkcs1pad_set_pub_key;
695 	inst->alg.set_priv_key = pkcs1pad_set_priv_key;
696 	inst->alg.max_size = pkcs1pad_get_max_size;
697 
698 	inst->free = pkcs1pad_free;
699 
700 	err = akcipher_register_instance(tmpl, inst);
701 	if (err) {
702 err_free_inst:
703 		pkcs1pad_free(inst);
704 	}
705 	return err;
706 }
707 
708 struct crypto_template rsa_pkcs1pad_tmpl = {
709 	.name = "pkcs1pad",
710 	.create = pkcs1pad_create,
711 	.module = THIS_MODULE,
712 };
713 
714 MODULE_ALIAS_CRYPTO("pkcs1pad");
715