crypto/asymmetric_keys/pkcs7_parser.c

   1 /* PKCS#7 parser
   2  *
   3  * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
   4  * Written by David Howells (dhowells@redhat.com)
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public Licence
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the Licence, or (at your option) any later version.
  10  */
  11
  12 #define pr_fmt(fmt) "PKCS7: "fmt
  13 #include <linux/kernel.h>
  14 #include <linux/export.h>
  15 #include <linux/slab.h>
  16 #include <linux/err.h>
  17 #include <linux/oid_registry.h>
  18 #include <crypto/public_key.h>
  19 #include "pkcs7_parser.h"
  20 #include "pkcs7-asn1.h"
  21
  22 struct pkcs7_parse_context {
  23         struct pkcs7_message    *msg;           /* Message being constructed */
  24         struct pkcs7_signed_info *sinfo;        /* SignedInfo being constructed */
  25         struct pkcs7_signed_info **ppsinfo;
  26         struct x509_certificate *certs;         /* Certificate cache */
  27         struct x509_certificate **ppcerts;
  28         unsigned long   data;                   /* Start of data */
  29         enum OID        last_oid;               /* Last OID encountered */
  30         unsigned        x509_index;
  31         unsigned        sinfo_index;
  32         const void      *raw_serial;
  33         unsigned        raw_serial_size;
  34         unsigned        raw_issuer_size;
  35         const void      *raw_issuer;
  36         const void      *raw_skid;
  37         unsigned        raw_skid_size;
  38         bool            expect_skid;
  39 };
  40
  41 /*
  42  * Free a signed information block.
  43  */
  44 static void pkcs7_free_signed_info(struct pkcs7_signed_info *sinfo)
  45 {
  46         if (sinfo) {
  47                 public_key_signature_free(sinfo->sig);
  48                 kfree(sinfo);
  49         }
  50 }
  51
  52 /**
  53  * pkcs7_free_message - Free a PKCS#7 message
  54  * @pkcs7: The PKCS#7 message to free
  55  */
  56 void pkcs7_free_message(struct pkcs7_message *pkcs7)
  57 {
  58         struct x509_certificate *cert;
  59         struct pkcs7_signed_info *sinfo;
  60
  61         if (pkcs7) {
  62                 while (pkcs7->certs) {
  63                         cert = pkcs7->certs;
  64                         pkcs7->certs = cert->next;
  65                         x509_free_certificate(cert);
  66                 }
  67                 while (pkcs7->crl) {
  68                         cert = pkcs7->crl;
  69                         pkcs7->crl = cert->next;
  70                         x509_free_certificate(cert);
  71                 }
  72                 while (pkcs7->signed_infos) {
  73                         sinfo = pkcs7->signed_infos;
  74                         pkcs7->signed_infos = sinfo->next;
  75                         pkcs7_free_signed_info(sinfo);
  76                 }
  77                 kfree(pkcs7);
  78         }
  79 }
  80 EXPORT_SYMBOL_GPL(pkcs7_free_message);
  81
  82 /*
  83  * Check authenticatedAttributes are provided or not provided consistently.
  84  */
  85 static int pkcs7_check_authattrs(struct pkcs7_message *msg)
  86 {
  87         struct pkcs7_signed_info *sinfo;
  88         bool want = false;
  89
  90         sinfo = msg->signed_infos;
  91         if (sinfo->authattrs) {
  92                 want = true;
  93                 msg->have_authattrs = true;
  94         }
  95
  96         for (sinfo = sinfo->next; sinfo; sinfo = sinfo->next)
  97                 if (!!sinfo->authattrs != want)
  98                         goto inconsistent;
  99         return 0;
 100
 101 inconsistent:
 102         pr_warn("Inconsistently supplied authAttrs\n");
 103         return -EINVAL;
 104 }
 105
 106 /**
 107  * pkcs7_parse_message - Parse a PKCS#7 message
 108  * @data: The raw binary ASN.1 encoded message to be parsed
 109  * @datalen: The size of the encoded message
 110  */
 111 struct pkcs7_message *pkcs7_parse_message(const void *data, size_t datalen)
 112 {
 113         struct pkcs7_parse_context *ctx;
 114         struct pkcs7_message *msg = ERR_PTR(-ENOMEM);
 115         int ret;
 116
 117         ctx = kzalloc(sizeof(struct pkcs7_parse_context), GFP_KERNEL);
 118         if (!ctx)
 119                 goto out_no_ctx;
 120         ctx->msg = kzalloc(sizeof(struct pkcs7_message), GFP_KERNEL);
 121         if (!ctx->msg)
 122                 goto out_no_msg;
 123         ctx->sinfo = kzalloc(sizeof(struct pkcs7_signed_info), GFP_KERNEL);
 124         if (!ctx->sinfo)
 125                 goto out_no_sinfo;
 126         ctx->sinfo->sig = kzalloc(sizeof(struct public_key_signature),
 127                                   GFP_KERNEL);
 128         if (!ctx->sinfo->sig)
 129                 goto out_no_sig;
 130
 131         ctx->data = (unsigned long)data;
 132         ctx->ppcerts = &ctx->certs;
 133         ctx->ppsinfo = &ctx->msg->signed_infos;
 134
 135         /* Attempt to decode the signature */
 136         ret = asn1_ber_decoder(&pkcs7_decoder, ctx, data, datalen);
 137         if (ret < 0) {
 138                 msg = ERR_PTR(ret);
 139                 goto out;
 140         }
 141
 142         ret = pkcs7_check_authattrs(ctx->msg);
 143         if (ret < 0)
 144                 goto out;
 145
 146         msg = ctx->msg;
 147         ctx->msg = NULL;
 148
 149 out:
 150         while (ctx->certs) {
 151                 struct x509_certificate *cert = ctx->certs;
 152                 ctx->certs = cert->next;
 153                 x509_free_certificate(cert);
 154         }
 155 out_no_sig:
 156         pkcs7_free_signed_info(ctx->sinfo);
 157 out_no_sinfo:
 158         pkcs7_free_message(ctx->msg);
 159 out_no_msg:
 160         kfree(ctx);
 161 out_no_ctx:
 162         return msg;
 163 }
 164 EXPORT_SYMBOL_GPL(pkcs7_parse_message);
 165
 166 /**
 167  * pkcs7_get_content_data - Get access to the PKCS#7 content
 168  * @pkcs7: The preparsed PKCS#7 message to access
 169  * @_data: Place to return a pointer to the data
 170  * @_data_len: Place to return the data length
 171  * @_headerlen: Size of ASN.1 header not included in _data
 172  *
 173  * Get access to the data content of the PKCS#7 message.  The size of the
 174  * header of the ASN.1 object that contains it is also provided and can be used
 175  * to adjust *_data and *_data_len to get the entire object.
 176  *
 177  * Returns -ENODATA if the data object was missing from the message.
 178  */
 179 int pkcs7_get_content_data(const struct pkcs7_message *pkcs7,
 180                            const void **_data, size_t *_data_len,
 181                            size_t *_headerlen)
 182 {
 183         if (!pkcs7->data)
 184                 return -ENODATA;
 185
 186         *_data = pkcs7->data;
 187         *_data_len = pkcs7->data_len;
 188         if (_headerlen)
 189                 *_headerlen = pkcs7->data_hdrlen;
 190         return 0;
 191 }
 192 EXPORT_SYMBOL_GPL(pkcs7_get_content_data);
 193
 194 /*
 195  * Note an OID when we find one for later processing when we know how
 196  * to interpret it.
 197  */
 198 int pkcs7_note_OID(void *context, size_t hdrlen,
 199                    unsigned char tag,
 200                    const void *value, size_t vlen)
 201 {
 202         struct pkcs7_parse_context *ctx = context;
 203
 204         ctx->last_oid = look_up_OID(value, vlen);
 205         if (ctx->last_oid == OID__NR) {
 206                 char buffer[50];
 207                 sprint_oid(value, vlen, buffer, sizeof(buffer));
 208                 printk("PKCS7: Unknown OID: [%lu] %s\n",
 209                        (unsigned long)value - ctx->data, buffer);
 210         }
 211         return 0;
 212 }
 213
 214 /*
 215  * Note the digest algorithm for the signature.
 216  */
 217 int pkcs7_sig_note_digest_algo(void *context, size_t hdrlen,
 218                                unsigned char tag,
 219                                const void *value, size_t vlen)
 220 {
 221         struct pkcs7_parse_context *ctx = context;
 222
 223         switch (ctx->last_oid) {
 224         case OID_md4:
 225                 ctx->sinfo->sig->hash_algo = "md4";
 226                 break;
 227         case OID_md5:
 228                 ctx->sinfo->sig->hash_algo = "md5";
 229                 break;
 230         case OID_sha1:
 231                 ctx->sinfo->sig->hash_algo = "sha1";
 232                 break;
 233         case OID_sha256:
 234                 ctx->sinfo->sig->hash_algo = "sha256";
 235                 break;
 236         case OID_sha384:
 237                 ctx->sinfo->sig->hash_algo = "sha384";
 238                 break;
 239         case OID_sha512:
 240                 ctx->sinfo->sig->hash_algo = "sha512";
 241                 break;
 242         case OID_sha224:
 243                 ctx->sinfo->sig->hash_algo = "sha224";
 244                 break;
 245         default:
 246                 printk("Unsupported digest algo: %u\n", ctx->last_oid);
 247                 return -ENOPKG;
 248         }
 249         return 0;
 250 }
 251
 252 /*
 253  * Note the public key algorithm for the signature.
 254  */
 255 int pkcs7_sig_note_pkey_algo(void *context, size_t hdrlen,
 256                              unsigned char tag,
 257                              const void *value, size_t vlen)
 258 {
 259         struct pkcs7_parse_context *ctx = context;
 260
 261         switch (ctx->last_oid) {
 262         case OID_rsaEncryption:
 263                 ctx->sinfo->sig->pkey_algo = "rsa";
 264                 break;
 265         default:
 266                 printk("Unsupported pkey algo: %u\n", ctx->last_oid);
 267                 return -ENOPKG;
 268         }
 269         return 0;
 270 }
 271
 272 /*
 273  * We only support signed data [RFC2315 sec 9].
 274  */
 275 int pkcs7_check_content_type(void *context, size_t hdrlen,
 276                              unsigned char tag,
 277                              const void *value, size_t vlen)
 278 {
 279         struct pkcs7_parse_context *ctx = context;
 280
 281         if (ctx->last_oid != OID_signed_data) {
 282                 pr_warn("Only support pkcs7_signedData type\n");
 283                 return -EINVAL;
 284         }
 285
 286         return 0;
 287 }
 288
 289 /*
 290  * Note the SignedData version
 291  */
 292 int pkcs7_note_signeddata_version(void *context, size_t hdrlen,
 293                                   unsigned char tag,
 294                                   const void *value, size_t vlen)
 295 {
 296         struct pkcs7_parse_context *ctx = context;
 297         unsigned version;
 298
 299         if (vlen != 1)
 300                 goto unsupported;
 301
 302         ctx->msg->version = version = *(const u8 *)value;
 303         switch (version) {
 304         case 1:
 305                 /* PKCS#7 SignedData [RFC2315 sec 9.1]
 306                  * CMS ver 1 SignedData [RFC5652 sec 5.1]
 307                  */
 308                 break;
 309         case 3:
 310                 /* CMS ver 3 SignedData [RFC2315 sec 5.1] */
 311                 break;
 312         default:
 313                 goto unsupported;
 314         }
 315
 316         return 0;
 317
 318 unsupported:
 319         pr_warn("Unsupported SignedData version\n");
 320         return -EINVAL;
 321 }
 322
 323 /*
 324  * Note the SignerInfo version
 325  */
 326 int pkcs7_note_signerinfo_version(void *context, size_t hdrlen,
 327                                   unsigned char tag,
 328                                   const void *value, size_t vlen)
 329 {
 330         struct pkcs7_parse_context *ctx = context;
 331         unsigned version;
 332
 333         if (vlen != 1)
 334                 goto unsupported;
 335
 336         version = *(const u8 *)value;
 337         switch (version) {
 338         case 1:
 339                 /* PKCS#7 SignerInfo [RFC2315 sec 9.2]
 340                  * CMS ver 1 SignerInfo [RFC5652 sec 5.3]
 341                  */
 342                 if (ctx->msg->version != 1)
 343                         goto version_mismatch;
 344                 ctx->expect_skid = false;
 345                 break;
 346         case 3:
 347                 /* CMS ver 3 SignerInfo [RFC2315 sec 5.3] */
 348                 if (ctx->msg->version == 1)
 349                         goto version_mismatch;
 350                 ctx->expect_skid = true;
 351                 break;
 352         default:
 353                 goto unsupported;
 354         }
 355
 356         return 0;
 357
 358 unsupported:
 359         pr_warn("Unsupported SignerInfo version\n");
 360         return -EINVAL;
 361 version_mismatch:
 362         pr_warn("SignedData-SignerInfo version mismatch\n");
 363         return -EBADMSG;
 364 }
 365
 366 /*
 367  * Extract a certificate and store it in the context.
 368  */
 369 int pkcs7_extract_cert(void *context, size_t hdrlen,
 370                        unsigned char tag,
 371                        const void *value, size_t vlen)
 372 {
 373         struct pkcs7_parse_context *ctx = context;
 374         struct x509_certificate *x509;
 375
 376         if (tag != ((ASN1_UNIV << 6) | ASN1_CONS_BIT | ASN1_SEQ)) {
 377                 pr_debug("Cert began with tag %02x at %lu\n",
 378                          tag, (unsigned long)ctx - ctx->data);
 379                 return -EBADMSG;
 380         }
 381
 382         /* We have to correct for the header so that the X.509 parser can start
 383          * from the beginning.  Note that since X.509 stipulates DER, there
 384          * probably shouldn't be an EOC trailer - but it is in PKCS#7 (which
 385          * stipulates BER).
 386          */
 387         value -= hdrlen;
 388         vlen += hdrlen;
 389
 390         if (((u8*)value)[1] == 0x80)
 391                 vlen += 2; /* Indefinite length - there should be an EOC */
 392
 393         x509 = x509_cert_parse(value, vlen);
 394         if (IS_ERR(x509))
 395                 return PTR_ERR(x509);
 396
 397         x509->index = ++ctx->x509_index;
 398         pr_debug("Got cert %u for %s\n", x509->index, x509->subject);
 399         pr_debug("- fingerprint %*phN\n", x509->id->len, x509->id->data);
 400
 401         *ctx->ppcerts = x509;
 402         ctx->ppcerts = &x509->next;
 403         return 0;
 404 }
 405
 406 /*
 407  * Save the certificate list
 408  */
 409 int pkcs7_note_certificate_list(void *context, size_t hdrlen,
 410                                 unsigned char tag,
 411                                 const void *value, size_t vlen)
 412 {
 413         struct pkcs7_parse_context *ctx = context;
 414
 415         pr_devel("Got cert list (%02x)\n", tag);
 416
 417         *ctx->ppcerts = ctx->msg->certs;
 418         ctx->msg->certs = ctx->certs;
 419         ctx->certs = NULL;
 420         ctx->ppcerts = &ctx->certs;
 421         return 0;
 422 }
 423
 424 /*
 425  * Note the content type.
 426  */
 427 int pkcs7_note_content(void *context, size_t hdrlen,
 428                        unsigned char tag,
 429                        const void *value, size_t vlen)
 430 {
 431         struct pkcs7_parse_context *ctx = context;
 432
 433         if (ctx->last_oid != OID_data &&
 434             ctx->last_oid != OID_msIndirectData) {
 435                 pr_warn("Unsupported data type %d\n", ctx->last_oid);
 436                 return -EINVAL;
 437         }
 438
 439         ctx->msg->data_type = ctx->last_oid;
 440         return 0;
 441 }
 442
 443 /*
 444  * Extract the data from the message and store that and its content type OID in
 445  * the context.
 446  */
 447 int pkcs7_note_data(void *context, size_t hdrlen,
 448                     unsigned char tag,
 449                     const void *value, size_t vlen)
 450 {
 451         struct pkcs7_parse_context *ctx = context;
 452
 453         pr_debug("Got data\n");
 454
 455         ctx->msg->data = value;
 456         ctx->msg->data_len = vlen;
 457         ctx->msg->data_hdrlen = hdrlen;
 458         return 0;
 459 }
 460
 461 /*
 462  * Parse authenticated attributes.
 463  */
 464 int pkcs7_sig_note_authenticated_attr(void *context, size_t hdrlen,
 465                                       unsigned char tag,
 466                                       const void *value, size_t vlen)
 467 {
 468         struct pkcs7_parse_context *ctx = context;
 469         struct pkcs7_signed_info *sinfo = ctx->sinfo;
 470         enum OID content_type;
 471
 472         pr_devel("AuthAttr: %02x %zu [%*ph]\n", tag, vlen, (unsigned)vlen, value);
 473
 474         switch (ctx->last_oid) {
 475         case OID_contentType:
 476                 if (__test_and_set_bit(sinfo_has_content_type, &sinfo->aa_set))
 477                         goto repeated;
 478                 content_type = look_up_OID(value, vlen);
 479                 if (content_type != ctx->msg->data_type) {
 480                         pr_warn("Mismatch between global data type (%d) and sinfo %u (%d)\n",
 481                                 ctx->msg->data_type, sinfo->index,
 482                                 content_type);
 483                         return -EBADMSG;
 484                 }
 485                 return 0;
 486
 487         case OID_signingTime:
 488                 if (__test_and_set_bit(sinfo_has_signing_time, &sinfo->aa_set))
 489                         goto repeated;
 490                 /* Should we check that the signing time is consistent
 491                  * with the signer's X.509 cert?
 492                  */
 493                 return x509_decode_time(&sinfo->signing_time,
 494                                         hdrlen, tag, value, vlen);
 495
 496         case OID_messageDigest:
 497                 if (__test_and_set_bit(sinfo_has_message_digest, &sinfo->aa_set))
 498                         goto repeated;
 499                 if (tag != ASN1_OTS)
 500                         return -EBADMSG;
 501                 sinfo->msgdigest = value;
 502                 sinfo->msgdigest_len = vlen;
 503                 return 0;
 504
 505         case OID_smimeCapabilites:
 506                 if (__test_and_set_bit(sinfo_has_smime_caps, &sinfo->aa_set))
 507                         goto repeated;
 508                 if (ctx->msg->data_type != OID_msIndirectData) {
 509                         pr_warn("S/MIME Caps only allowed with Authenticode\n");
 510                         return -EKEYREJECTED;
 511                 }
 512                 return 0;
 513
 514                 /* Microsoft SpOpusInfo seems to be contain cont[0] 16-bit BE
 515                  * char URLs and cont[1] 8-bit char URLs.
 516                  *
 517                  * Microsoft StatementType seems to contain a list of OIDs that
 518                  * are also used as extendedKeyUsage types in X.509 certs.
 519                  */
 520         case OID_msSpOpusInfo:
 521                 if (__test_and_set_bit(sinfo_has_ms_opus_info, &sinfo->aa_set))
 522                         goto repeated;
 523                 goto authenticode_check;
 524         case OID_msStatementType:
 525                 if (__test_and_set_bit(sinfo_has_ms_statement_type, &sinfo->aa_set))
 526                         goto repeated;
 527         authenticode_check:
 528                 if (ctx->msg->data_type != OID_msIndirectData) {
 529                         pr_warn("Authenticode AuthAttrs only allowed with Authenticode\n");
 530                         return -EKEYREJECTED;
 531                 }
 532                 /* I'm not sure how to validate these */
 533                 return 0;
 534         default:
 535                 return 0;
 536         }
 537
 538 repeated:
 539         /* We permit max one item per AuthenticatedAttribute and no repeats */
 540         pr_warn("Repeated/multivalue AuthAttrs not permitted\n");
 541         return -EKEYREJECTED;
 542 }
 543
 544 /*
 545  * Note the set of auth attributes for digestion purposes [RFC2315 sec 9.3]
 546  */
 547 int pkcs7_sig_note_set_of_authattrs(void *context, size_t hdrlen,
 548                                     unsigned char tag,
 549                                     const void *value, size_t vlen)
 550 {
 551         struct pkcs7_parse_context *ctx = context;
 552         struct pkcs7_signed_info *sinfo = ctx->sinfo;
 553
 554         if (!test_bit(sinfo_has_content_type, &sinfo->aa_set) ||
 555             !test_bit(sinfo_has_message_digest, &sinfo->aa_set)) {
 556                 pr_warn("Missing required AuthAttr\n");
 557                 return -EBADMSG;
 558         }
 559
 560         if (ctx->msg->data_type != OID_msIndirectData &&
 561             test_bit(sinfo_has_ms_opus_info, &sinfo->aa_set)) {
 562                 pr_warn("Unexpected Authenticode AuthAttr\n");
 563                 return -EBADMSG;
 564         }
 565
 566         /* We need to switch the 'CONT 0' to a 'SET OF' when we digest */
 567         sinfo->authattrs = value - (hdrlen - 1);
 568         sinfo->authattrs_len = vlen + (hdrlen - 1);
 569         return 0;
 570 }
 571
 572 /*
 573  * Note the issuing certificate serial number
 574  */
 575 int pkcs7_sig_note_serial(void *context, size_t hdrlen,
 576                           unsigned char tag,
 577                           const void *value, size_t vlen)
 578 {
 579         struct pkcs7_parse_context *ctx = context;
 580         ctx->raw_serial = value;
 581         ctx->raw_serial_size = vlen;
 582         return 0;
 583 }
 584
 585 /*
 586  * Note the issuer's name
 587  */
 588 int pkcs7_sig_note_issuer(void *context, size_t hdrlen,
 589                           unsigned char tag,
 590                           const void *value, size_t vlen)
 591 {
 592         struct pkcs7_parse_context *ctx = context;
 593         ctx->raw_issuer = value;
 594         ctx->raw_issuer_size = vlen;
 595         return 0;
 596 }
 597
 598 /*
 599  * Note the issuing cert's subjectKeyIdentifier
 600  */
 601 int pkcs7_sig_note_skid(void *context, size_t hdrlen,
 602                         unsigned char tag,
 603                         const void *value, size_t vlen)
 604 {
 605         struct pkcs7_parse_context *ctx = context;
 606
 607         pr_devel("SKID: %02x %zu [%*ph]\n", tag, vlen, (unsigned)vlen, value);
 608
 609         ctx->raw_skid = value;
 610         ctx->raw_skid_size = vlen;
 611         return 0;
 612 }
 613
 614 /*
 615  * Note the signature data
 616  */
 617 int pkcs7_sig_note_signature(void *context, size_t hdrlen,
 618                              unsigned char tag,
 619                              const void *value, size_t vlen)
 620 {
 621         struct pkcs7_parse_context *ctx = context;
 622
 623         ctx->sinfo->sig->s = kmemdup(value, vlen, GFP_KERNEL);
 624         if (!ctx->sinfo->sig->s)
 625                 return -ENOMEM;
 626
 627         ctx->sinfo->sig->s_size = vlen;
 628         return 0;
 629 }
 630
 631 /*
 632  * Note a signature information block
 633  */
 634 int pkcs7_note_signed_info(void *context, size_t hdrlen,
 635                            unsigned char tag,
 636                            const void *value, size_t vlen)
 637 {
 638         struct pkcs7_parse_context *ctx = context;
 639         struct pkcs7_signed_info *sinfo = ctx->sinfo;
 640         struct asymmetric_key_id *kid;
 641
 642         if (ctx->msg->data_type == OID_msIndirectData && !sinfo->authattrs) {
 643                 pr_warn("Authenticode requires AuthAttrs\n");
 644                 return -EBADMSG;
 645         }
 646
 647         /* Generate cert issuer + serial number key ID */
 648         if (!ctx->expect_skid) {
 649                 kid = asymmetric_key_generate_id(ctx->raw_serial,
 650                                                  ctx->raw_serial_size,
 651                                                  ctx->raw_issuer,
 652                                                  ctx->raw_issuer_size);
 653         } else {
 654                 kid = asymmetric_key_generate_id(ctx->raw_skid,
 655                                                  ctx->raw_skid_size,
 656                                                  "", 0);
 657         }
 658         if (IS_ERR(kid))
 659                 return PTR_ERR(kid);
 660
 661         pr_devel("SINFO KID: %u [%*phN]\n", kid->len, kid->len, kid->data);
 662
 663         sinfo->sig->auth_ids[0] = kid;
 664         sinfo->index = ++ctx->sinfo_index;
 665         *ctx->ppsinfo = sinfo;
 666         ctx->ppsinfo = &sinfo->next;
 667         ctx->sinfo = kzalloc(sizeof(struct pkcs7_signed_info), GFP_KERNEL);
 668         if (!ctx->sinfo)
 669                 return -ENOMEM;
 670         ctx->sinfo->sig = kzalloc(sizeof(struct public_key_signature),
 671                                   GFP_KERNEL);
 672         if (!ctx->sinfo->sig)
 673                 return -ENOMEM;
 674         return 0;
 675 }