crypto/rsa-pkcs1pad.c

   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_ATOMIC);
 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         digest_size = digest_info->size;
 396
 397         if (req->src_len + digest_size > ctx->key_size - 11)
 398                 return -EOVERFLOW;
 399
 400         if (req->dst_len < ctx->key_size) {
 401                 req->dst_len = ctx->key_size;
 402                 return -EOVERFLOW;
 403         }
 404
 405         req_ctx->in_buf = kmalloc(ctx->key_size - 1 - req->src_len,
 406                                   GFP_KERNEL);
 407         if (!req_ctx->in_buf)
 408                 return -ENOMEM;
 409
 410         ps_end = ctx->key_size - digest_size - req->src_len - 2;
 411         req_ctx->in_buf[0] = 0x01;
 412         memset(req_ctx->in_buf + 1, 0xff, ps_end - 1);
 413         req_ctx->in_buf[ps_end] = 0x00;
 414
 415         memcpy(req_ctx->in_buf + ps_end + 1, digest_info->data,
 416                digest_info->size);
 417
 418         pkcs1pad_sg_set_buf(req_ctx->in_sg, req_ctx->in_buf,
 419                         ctx->key_size - 1 - req->src_len, req->src);
 420
 421         akcipher_request_set_tfm(&req_ctx->child_req, ctx->child);
 422         akcipher_request_set_callback(&req_ctx->child_req, req->base.flags,
 423                         pkcs1pad_encrypt_sign_complete_cb, req);
 424
 425         /* Reuse output buffer */
 426         akcipher_request_set_crypt(&req_ctx->child_req, req_ctx->in_sg,
 427                                    req->dst, ctx->key_size - 1, req->dst_len);
 428
 429         err = crypto_akcipher_sign(&req_ctx->child_req);
 430         if (err != -EINPROGRESS && err != -EBUSY)
 431                 return pkcs1pad_encrypt_sign_complete(req, err);
 432
 433         return err;
 434 }
 435
 436 static int pkcs1pad_verify_complete(struct akcipher_request *req, int err)
 437 {
 438         struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
 439         struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
 440         struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
 441         struct akcipher_instance *inst = akcipher_alg_instance(tfm);
 442         struct pkcs1pad_inst_ctx *ictx = akcipher_instance_ctx(inst);
 443         const struct rsa_asn1_template *digest_info = ictx->digest_info;
 444         unsigned int dst_len;
 445         unsigned int pos;
 446         u8 *out_buf;
 447
 448         if (err)
 449                 goto done;
 450
 451         err = -EINVAL;
 452         dst_len = req_ctx->child_req.dst_len;
 453         if (dst_len < ctx->key_size - 1)
 454                 goto done;
 455
 456         out_buf = req_ctx->out_buf;
 457         if (dst_len == ctx->key_size) {
 458                 if (out_buf[0] != 0x00)
 459                         /* Decrypted value had no leading 0 byte */
 460                         goto done;
 461
 462                 dst_len--;
 463                 out_buf++;
 464         }
 465
 466         err = -EBADMSG;
 467         if (out_buf[0] != 0x01)
 468                 goto done;
 469
 470         for (pos = 1; pos < dst_len; pos++)
 471                 if (out_buf[pos] != 0xff)
 472                         break;
 473
 474         if (pos < 9 || pos == dst_len || out_buf[pos] != 0x00)
 475                 goto done;
 476         pos++;
 477
 478         if (crypto_memneq(out_buf + pos, digest_info->data, digest_info->size))
 479                 goto done;
 480
 481         pos += digest_info->size;
 482
 483         err = 0;
 484
 485         if (req->dst_len < dst_len - pos)
 486                 err = -EOVERFLOW;
 487         req->dst_len = dst_len - pos;
 488
 489         if (!err)
 490                 sg_copy_from_buffer(req->dst,
 491                                 sg_nents_for_len(req->dst, req->dst_len),
 492                                 out_buf + pos, req->dst_len);
 493 done:
 494         kzfree(req_ctx->out_buf);
 495
 496         return err;
 497 }
 498
 499 static void pkcs1pad_verify_complete_cb(
 500                 struct crypto_async_request *child_async_req, int err)
 501 {
 502         struct akcipher_request *req = child_async_req->data;
 503         struct crypto_async_request async_req;
 504
 505         if (err == -EINPROGRESS)
 506                 return;
 507
 508         async_req.data = req->base.data;
 509         async_req.tfm = crypto_akcipher_tfm(crypto_akcipher_reqtfm(req));
 510         async_req.flags = child_async_req->flags;
 511         req->base.complete(&async_req, pkcs1pad_verify_complete(req, err));
 512 }
 513
 514 /*
 515  * The verify operation is here for completeness similar to the verification
 516  * defined in RFC2313 section 10.2 except that block type 0 is not accepted,
 517  * as in RFC2437.  RFC2437 section 9.2 doesn't define any operation to
 518  * retrieve the DigestInfo from a signature, instead the user is expected
 519  * to call the sign operation to generate the expected signature and compare
 520  * signatures instead of the message-digests.
 521  */
 522 static int pkcs1pad_verify(struct akcipher_request *req)
 523 {
 524         struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
 525         struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
 526         struct pkcs1pad_request *req_ctx = akcipher_request_ctx(req);
 527         int err;
 528
 529         if (!ctx->key_size || req->src_len < ctx->key_size)
 530                 return -EINVAL;
 531
 532         req_ctx->out_buf = kmalloc(ctx->key_size, GFP_KERNEL);
 533         if (!req_ctx->out_buf)
 534                 return -ENOMEM;
 535
 536         pkcs1pad_sg_set_buf(req_ctx->out_sg, req_ctx->out_buf,
 537                             ctx->key_size, NULL);
 538
 539         akcipher_request_set_tfm(&req_ctx->child_req, ctx->child);
 540         akcipher_request_set_callback(&req_ctx->child_req, req->base.flags,
 541                         pkcs1pad_verify_complete_cb, req);
 542
 543         /* Reuse input buffer, output to a new buffer */
 544         akcipher_request_set_crypt(&req_ctx->child_req, req->src,
 545                                    req_ctx->out_sg, req->src_len,
 546                                    ctx->key_size);
 547
 548         err = crypto_akcipher_verify(&req_ctx->child_req);
 549         if (err != -EINPROGRESS && err != -EBUSY)
 550                 return pkcs1pad_verify_complete(req, err);
 551
 552         return err;
 553 }
 554
 555 static int pkcs1pad_init_tfm(struct crypto_akcipher *tfm)
 556 {
 557         struct akcipher_instance *inst = akcipher_alg_instance(tfm);
 558         struct pkcs1pad_inst_ctx *ictx = akcipher_instance_ctx(inst);
 559         struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
 560         struct crypto_akcipher *child_tfm;
 561
 562         child_tfm = crypto_spawn_akcipher(&ictx->spawn);
 563         if (IS_ERR(child_tfm))
 564                 return PTR_ERR(child_tfm);
 565
 566         ctx->child = child_tfm;
 567         return 0;
 568 }
 569
 570 static void pkcs1pad_exit_tfm(struct crypto_akcipher *tfm)
 571 {
 572         struct pkcs1pad_ctx *ctx = akcipher_tfm_ctx(tfm);
 573
 574         crypto_free_akcipher(ctx->child);
 575 }
 576
 577 static void pkcs1pad_free(struct akcipher_instance *inst)
 578 {
 579         struct pkcs1pad_inst_ctx *ctx = akcipher_instance_ctx(inst);
 580         struct crypto_akcipher_spawn *spawn = &ctx->spawn;
 581
 582         crypto_drop_akcipher(spawn);
 583         kfree(inst);
 584 }
 585
 586 static int pkcs1pad_create(struct crypto_template *tmpl, struct rtattr **tb)
 587 {
 588         const struct rsa_asn1_template *digest_info;
 589         struct crypto_attr_type *algt;
 590         struct akcipher_instance *inst;
 591         struct pkcs1pad_inst_ctx *ctx;
 592         struct crypto_akcipher_spawn *spawn;
 593         struct akcipher_alg *rsa_alg;
 594         const char *rsa_alg_name;
 595         const char *hash_name;
 596         int err;
 597
 598         algt = crypto_get_attr_type(tb);
 599         if (IS_ERR(algt))
 600                 return PTR_ERR(algt);
 601
 602         if ((algt->type ^ CRYPTO_ALG_TYPE_AKCIPHER) & algt->mask)
 603                 return -EINVAL;
 604
 605         rsa_alg_name = crypto_attr_alg_name(tb[1]);
 606         if (IS_ERR(rsa_alg_name))
 607                 return PTR_ERR(rsa_alg_name);
 608
 609         hash_name = crypto_attr_alg_name(tb[2]);
 610         if (IS_ERR(hash_name))
 611                 return PTR_ERR(hash_name);
 612
 613         digest_info = rsa_lookup_asn1(hash_name);
 614         if (!digest_info)
 615                 return -EINVAL;
 616
 617         inst = kzalloc(sizeof(*inst) + sizeof(*ctx), GFP_KERNEL);
 618         if (!inst)
 619                 return -ENOMEM;
 620
 621         ctx = akcipher_instance_ctx(inst);
 622         spawn = &ctx->spawn;
 623         ctx->digest_info = digest_info;
 624
 625         crypto_set_spawn(&spawn->base, akcipher_crypto_instance(inst));
 626         err = crypto_grab_akcipher(spawn, rsa_alg_name, 0,
 627                         crypto_requires_sync(algt->type, algt->mask));
 628         if (err)
 629                 goto out_free_inst;
 630
 631         rsa_alg = crypto_spawn_akcipher_alg(spawn);
 632
 633         err = -ENAMETOOLONG;
 634
 635         if (snprintf(inst->alg.base.cra_name, CRYPTO_MAX_ALG_NAME,
 636                      "pkcs1pad(%s,%s)", rsa_alg->base.cra_name, hash_name) >=
 637             CRYPTO_MAX_ALG_NAME ||
 638             snprintf(inst->alg.base.cra_driver_name, CRYPTO_MAX_ALG_NAME,
 639                      "pkcs1pad(%s,%s)",
 640                      rsa_alg->base.cra_driver_name, hash_name) >=
 641             CRYPTO_MAX_ALG_NAME)
 642                 goto out_drop_alg;
 643
 644         inst->alg.base.cra_flags = rsa_alg->base.cra_flags & CRYPTO_ALG_ASYNC;
 645         inst->alg.base.cra_priority = rsa_alg->base.cra_priority;
 646         inst->alg.base.cra_ctxsize = sizeof(struct pkcs1pad_ctx);
 647
 648         inst->alg.init = pkcs1pad_init_tfm;
 649         inst->alg.exit = pkcs1pad_exit_tfm;
 650
 651         inst->alg.encrypt = pkcs1pad_encrypt;
 652         inst->alg.decrypt = pkcs1pad_decrypt;
 653         inst->alg.sign = pkcs1pad_sign;
 654         inst->alg.verify = pkcs1pad_verify;
 655         inst->alg.set_pub_key = pkcs1pad_set_pub_key;
 656         inst->alg.set_priv_key = pkcs1pad_set_priv_key;
 657         inst->alg.max_size = pkcs1pad_get_max_size;
 658         inst->alg.reqsize = sizeof(struct pkcs1pad_request) + rsa_alg->reqsize;
 659
 660         inst->free = pkcs1pad_free;
 661
 662         err = akcipher_register_instance(tmpl, inst);
 663         if (err)
 664                 goto out_drop_alg;
 665
 666         return 0;
 667
 668 out_drop_alg:
 669         crypto_drop_akcipher(spawn);
 670 out_free_inst:
 671         kfree(inst);
 672         return err;
 673 }
 674
 675 struct crypto_template rsa_pkcs1pad_tmpl = {
 676         .name = "pkcs1pad",
 677         .create = pkcs1pad_create,
 678         .module = THIS_MODULE,
 679 };