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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 
rsa_lookup_asn1(const char * name)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 
pkcs1pad_set_pub_key(struct crypto_akcipher * tfm,const void * key,unsigned int keylen)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 
pkcs1pad_set_priv_key(struct crypto_akcipher * tfm,const void * key,unsigned int keylen)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 
pkcs1pad_get_max_size(struct crypto_akcipher * tfm)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 
pkcs1pad_sg_set_buf(struct scatterlist * sg,void * buf,size_t len,struct scatterlist * next)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 
pkcs1pad_encrypt_sign_complete(struct akcipher_request * req,int err)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 
pkcs1pad_encrypt_sign_complete_cb(struct crypto_async_request * child_async_req,int err)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 
217 	if (err == -EINPROGRESS)
218 		goto out;
219 
220 	err = pkcs1pad_encrypt_sign_complete(req, err);
221 
222 out:
223 	akcipher_request_complete(req, err);
224 }
225 
pkcs1pad_encrypt(struct akcipher_request * req)226 static int pkcs1pad_encrypt(struct akcipher_request *req)
227 {
228 	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
229 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
230 	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
231 	int err;
232 	unsigned int i, ps_end;
233 
234 	if (!ctx->key_size)
235 		return -EINVAL;
236 
237 	if (req->src_len > ctx->key_size - 11)
238 		return -EOVERFLOW;
239 
240 	if (req->dst_len < ctx->key_size) {
241 		req->dst_len = ctx->key_size;
242 		return -EOVERFLOW;
243 	}
244 
245 	req_ctx->in_buf = kmalloc(ctx->key_size - 1 - req->src_len,
246 				  GFP_KERNEL);
247 	if (!req_ctx->in_buf)
248 		return -ENOMEM;
249 
250 	ps_end = ctx->key_size - req->src_len - 2;
251 	req_ctx->in_buf[0] = 0x02;
252 	for (i = 1; i < ps_end; i++)
253 		req_ctx->in_buf[i] = 1 + prandom_u32_max(255);
254 	req_ctx->in_buf[ps_end] = 0x00;
255 
256 	pkcs1pad_sg_set_buf(req_ctx->in_sg, req_ctx->in_buf,
257 			ctx->key_size - 1 - req->src_len, req->src);
258 
259 	akcipher_request_set_tfm(&req_ctx->child_req, ctx->child);
260 	akcipher_request_set_callback(&req_ctx->child_req, req->base.flags,
261 			pkcs1pad_encrypt_sign_complete_cb, req);
262 
263 	/* Reuse output buffer */
264 	akcipher_request_set_crypt(&req_ctx->child_req, req_ctx->in_sg,
265 				   req->dst, ctx->key_size - 1, req->dst_len);
266 
267 	err = crypto_akcipher_encrypt(&req_ctx->child_req);
268 	if (err != -EINPROGRESS && err != -EBUSY)
269 		return pkcs1pad_encrypt_sign_complete(req, err);
270 
271 	return err;
272 }
273 
pkcs1pad_decrypt_complete(struct akcipher_request * req,int err)274 static int pkcs1pad_decrypt_complete(struct akcipher_request *req, int err)
275 {
276 	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
277 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
278 	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
279 	unsigned int dst_len;
280 	unsigned int pos;
281 	u8 *out_buf;
282 
283 	if (err)
284 		goto done;
285 
286 	err = -EINVAL;
287 	dst_len = req_ctx->child_req.dst_len;
288 	if (dst_len < ctx->key_size - 1)
289 		goto done;
290 
291 	out_buf = req_ctx->out_buf;
292 	if (dst_len == ctx->key_size) {
293 		if (out_buf[0] != 0x00)
294 			/* Decrypted value had no leading 0 byte */
295 			goto done;
296 
297 		dst_len--;
298 		out_buf++;
299 	}
300 
301 	if (out_buf[0] != 0x02)
302 		goto done;
303 
304 	for (pos = 1; pos < dst_len; pos++)
305 		if (out_buf[pos] == 0x00)
306 			break;
307 	if (pos < 9 || pos == dst_len)
308 		goto done;
309 	pos++;
310 
311 	err = 0;
312 
313 	if (req->dst_len < dst_len - pos)
314 		err = -EOVERFLOW;
315 	req->dst_len = dst_len - pos;
316 
317 	if (!err)
318 		sg_copy_from_buffer(req->dst,
319 				sg_nents_for_len(req->dst, req->dst_len),
320 				out_buf + pos, req->dst_len);
321 
322 done:
323 	kzfree(req_ctx->out_buf);
324 
325 	return err;
326 }
327 
pkcs1pad_decrypt_complete_cb(struct crypto_async_request * child_async_req,int err)328 static void pkcs1pad_decrypt_complete_cb(
329 		struct crypto_async_request *child_async_req, int err)
330 {
331 	struct akcipher_request *req = child_async_req->data;
332 
333 	if (err == -EINPROGRESS)
334 		goto out;
335 
336 	err = pkcs1pad_decrypt_complete(req, err);
337 
338 out:
339 	akcipher_request_complete(req, err);
340 }
341 
pkcs1pad_decrypt(struct akcipher_request * req)342 static int pkcs1pad_decrypt(struct akcipher_request *req)
343 {
344 	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
345 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
346 	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
347 	int err;
348 
349 	if (!ctx->key_size || req->src_len != ctx->key_size)
350 		return -EINVAL;
351 
352 	req_ctx->out_buf = kmalloc(ctx->key_size, GFP_KERNEL);
353 	if (!req_ctx->out_buf)
354 		return -ENOMEM;
355 
356 	pkcs1pad_sg_set_buf(req_ctx->out_sg, req_ctx->out_buf,
357 			    ctx->key_size, NULL);
358 
359 	akcipher_request_set_tfm(&req_ctx->child_req, ctx->child);
360 	akcipher_request_set_callback(&req_ctx->child_req, req->base.flags,
361 			pkcs1pad_decrypt_complete_cb, req);
362 
363 	/* Reuse input buffer, output to a new buffer */
364 	akcipher_request_set_crypt(&req_ctx->child_req, req->src,
365 				   req_ctx->out_sg, req->src_len,
366 				   ctx->key_size);
367 
368 	err = crypto_akcipher_decrypt(&req_ctx->child_req);
369 	if (err != -EINPROGRESS && err != -EBUSY)
370 		return pkcs1pad_decrypt_complete(req, err);
371 
372 	return err;
373 }
374 
pkcs1pad_sign(struct akcipher_request * req)375 static int pkcs1pad_sign(struct akcipher_request *req)
376 {
377 	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
378 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
379 	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
380 	struct akcipher_instance *inst = akcipher_alg_instance(tfm);
381 	struct pkcs1pad_inst_ctx *ictx = akcipher_instance_ctx(inst);
382 	const struct rsa_asn1_template *digest_info = ictx->digest_info;
383 	int err;
384 	unsigned int ps_end, digest_size = 0;
385 
386 	if (!ctx->key_size)
387 		return -EINVAL;
388 
389 	if (digest_info)
390 		digest_size = digest_info->size;
391 
392 	if (req->src_len + digest_size > ctx->key_size - 11)
393 		return -EOVERFLOW;
394 
395 	if (req->dst_len < ctx->key_size) {
396 		req->dst_len = ctx->key_size;
397 		return -EOVERFLOW;
398 	}
399 
400 	req_ctx->in_buf = kmalloc(ctx->key_size - 1 - req->src_len,
401 				  GFP_KERNEL);
402 	if (!req_ctx->in_buf)
403 		return -ENOMEM;
404 
405 	ps_end = ctx->key_size - digest_size - req->src_len - 2;
406 	req_ctx->in_buf[0] = 0x01;
407 	memset(req_ctx->in_buf + 1, 0xff, ps_end - 1);
408 	req_ctx->in_buf[ps_end] = 0x00;
409 
410 	if (digest_info)
411 		memcpy(req_ctx->in_buf + ps_end + 1, digest_info->data,
412 		       digest_info->size);
413 
414 	pkcs1pad_sg_set_buf(req_ctx->in_sg, req_ctx->in_buf,
415 			ctx->key_size - 1 - req->src_len, req->src);
416 
417 	akcipher_request_set_tfm(&req_ctx->child_req, ctx->child);
418 	akcipher_request_set_callback(&req_ctx->child_req, req->base.flags,
419 			pkcs1pad_encrypt_sign_complete_cb, req);
420 
421 	/* Reuse output buffer */
422 	akcipher_request_set_crypt(&req_ctx->child_req, req_ctx->in_sg,
423 				   req->dst, ctx->key_size - 1, req->dst_len);
424 
425 	err = crypto_akcipher_decrypt(&req_ctx->child_req);
426 	if (err != -EINPROGRESS && err != -EBUSY)
427 		return pkcs1pad_encrypt_sign_complete(req, err);
428 
429 	return err;
430 }
431 
pkcs1pad_verify_complete(struct akcipher_request * req,int err)432 static int pkcs1pad_verify_complete(struct akcipher_request *req, int err)
433 {
434 	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
435 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
436 	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
437 	struct akcipher_instance *inst = akcipher_alg_instance(tfm);
438 	struct pkcs1pad_inst_ctx *ictx = akcipher_instance_ctx(inst);
439 	const struct rsa_asn1_template *digest_info = ictx->digest_info;
440 	unsigned int dst_len;
441 	unsigned int pos;
442 	u8 *out_buf;
443 
444 	if (err)
445 		goto done;
446 
447 	err = -EINVAL;
448 	dst_len = req_ctx->child_req.dst_len;
449 	if (dst_len < ctx->key_size - 1)
450 		goto done;
451 
452 	out_buf = req_ctx->out_buf;
453 	if (dst_len == ctx->key_size) {
454 		if (out_buf[0] != 0x00)
455 			/* Decrypted value had no leading 0 byte */
456 			goto done;
457 
458 		dst_len--;
459 		out_buf++;
460 	}
461 
462 	err = -EBADMSG;
463 	if (out_buf[0] != 0x01)
464 		goto done;
465 
466 	for (pos = 1; pos < dst_len; pos++)
467 		if (out_buf[pos] != 0xff)
468 			break;
469 
470 	if (pos < 9 || pos == dst_len || out_buf[pos] != 0x00)
471 		goto done;
472 	pos++;
473 
474 	if (digest_info) {
475 		if (digest_info->size > dst_len - pos)
476 			goto done;
477 		if (crypto_memneq(out_buf + pos, digest_info->data,
478 				  digest_info->size))
479 			goto done;
480 
481 		pos += digest_info->size;
482 	}
483 
484 	err = 0;
485 
486 	if (req->dst_len != dst_len - pos) {
487 		err = -EKEYREJECTED;
488 		req->dst_len = dst_len - pos;
489 		goto done;
490 	}
491 	/* Extract appended digest. */
492 	sg_pcopy_to_buffer(req->src,
493 			   sg_nents_for_len(req->src,
494 					    req->src_len + req->dst_len),
495 			   req_ctx->out_buf + ctx->key_size,
496 			   req->dst_len, req->src_len);
497 	/* Do the actual verification step. */
498 	if (memcmp(req_ctx->out_buf + ctx->key_size, out_buf + pos,
499 		   req->dst_len) != 0)
500 		err = -EKEYREJECTED;
501 done:
502 	kzfree(req_ctx->out_buf);
503 
504 	return err;
505 }
506 
pkcs1pad_verify_complete_cb(struct crypto_async_request * child_async_req,int err)507 static void pkcs1pad_verify_complete_cb(
508 		struct crypto_async_request *child_async_req, int err)
509 {
510 	struct akcipher_request *req = child_async_req->data;
511 
512 	if (err == -EINPROGRESS)
513 		goto out;
514 
515 	err = pkcs1pad_verify_complete(req, err);
516 
517 out:
518 	akcipher_request_complete(req, err);
519 }
520 
521 /*
522  * The verify operation is here for completeness similar to the verification
523  * defined in RFC2313 section 10.2 except that block type 0 is not accepted,
524  * as in RFC2437.  RFC2437 section 9.2 doesn't define any operation to
525  * retrieve the DigestInfo from a signature, instead the user is expected
526  * to call the sign operation to generate the expected signature and compare
527  * signatures instead of the message-digests.
528  */
pkcs1pad_verify(struct akcipher_request * req)529 static int pkcs1pad_verify(struct akcipher_request *req)
530 {
531 	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
532 	struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
533 	struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
534 	int err;
535 
536 	if (WARN_ON(req->dst) ||
537 	    WARN_ON(!req->dst_len) ||
538 	    !ctx->key_size || req->src_len != ctx->key_size)
539 		return -EINVAL;
540 
541 	req_ctx->out_buf = kmalloc(ctx->key_size + req->dst_len, 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_encrypt(&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 		hash_name = NULL;
621 
622 	if (hash_name) {
623 		digest_info = rsa_lookup_asn1(hash_name);
624 		if (!digest_info)
625 			return -EINVAL;
626 	} else
627 		digest_info = NULL;
628 
629 	inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
630 	if (!inst)
631 		return -ENOMEM;
632 
633 	ctx = akcipher_instance_ctx(inst);
634 	spawn = &ctx->spawn;
635 	ctx->digest_info = digest_info;
636 
637 	crypto_set_spawn(&spawn->base, akcipher_crypto_instance(inst));
638 	err = crypto_grab_akcipher(spawn, rsa_alg_name, 0,
639 			crypto_requires_sync(algt->type, algt->mask));
640 	if (err)
641 		goto out_free_inst;
642 
643 	rsa_alg = crypto_spawn_akcipher_alg(spawn);
644 
645 	err = -ENAMETOOLONG;
646 
647 	if (!hash_name) {
648 		if (snprintf(inst->alg.base.cra_name,
649 			     CRYPTO_MAX_ALG_NAME, "pkcs1pad(%s)",
650 			     rsa_alg->base.cra_name) >= CRYPTO_MAX_ALG_NAME)
651 			goto out_drop_alg;
652 
653 		if (snprintf(inst->alg.base.cra_driver_name,
654 			     CRYPTO_MAX_ALG_NAME, "pkcs1pad(%s)",
655 			     rsa_alg->base.cra_driver_name) >=
656 			     CRYPTO_MAX_ALG_NAME)
657 			goto out_drop_alg;
658 	} else {
659 		if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
660 			     "pkcs1pad(%s,%s)", rsa_alg->base.cra_name,
661 			     hash_name) >= CRYPTO_MAX_ALG_NAME)
662 			goto out_drop_alg;
663 
664 		if (snprintf(inst->alg.base.cra_driver_name,
665 			     CRYPTO_MAX_ALG_NAME, "pkcs1pad(%s,%s)",
666 			     rsa_alg->base.cra_driver_name,
667 			     hash_name) >= CRYPTO_MAX_ALG_NAME)
668 			goto out_drop_alg;
669 	}
670 
671 	inst->alg.base.cra_flags = rsa_alg->base.cra_flags & CRYPTO_ALG_ASYNC;
672 	inst->alg.base.cra_priority = rsa_alg->base.cra_priority;
673 	inst->alg.base.cra_ctxsize = sizeof(struct pkcs1pad_ctx);
674 
675 	inst->alg.init = pkcs1pad_init_tfm;
676 	inst->alg.exit = pkcs1pad_exit_tfm;
677 
678 	inst->alg.encrypt = pkcs1pad_encrypt;
679 	inst->alg.decrypt = pkcs1pad_decrypt;
680 	inst->alg.sign = pkcs1pad_sign;
681 	inst->alg.verify = pkcs1pad_verify;
682 	inst->alg.set_pub_key = pkcs1pad_set_pub_key;
683 	inst->alg.set_priv_key = pkcs1pad_set_priv_key;
684 	inst->alg.max_size = pkcs1pad_get_max_size;
685 	inst->alg.reqsize = sizeof(struct pkcs1pad_request) + rsa_alg->reqsize;
686 
687 	inst->free = pkcs1pad_free;
688 
689 	err = akcipher_register_instance(tmpl, inst);
690 	if (err)
691 		goto out_drop_alg;
692 
693 	return 0;
694 
695 out_drop_alg:
696 	crypto_drop_akcipher(spawn);
697 out_free_inst:
698 	kfree(inst);
699 	return err;
700 }
701 
702 struct crypto_template rsa_pkcs1pad_tmpl = {
703 	.name = "pkcs1pad",
704 	.create = pkcs1pad_create,
705 	.module = THIS_MODULE,
706 };
707