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/module.h>
  15 #include <linux/export.h>
  16 #include <linux/slab.h>
  17 #include <linux/err.h>
  18 #include <linux/oid_registry.h>
  19 #include <crypto/public_key.h>
  20 #include "pkcs7_parser.h"
  21 #include "pkcs7-asn1.h"
  22
  23 MODULE_DESCRIPTION("PKCS#7 parser");
  24 MODULE_AUTHOR("Red Hat, Inc.");
  25 MODULE_LICENSE("GPL");
  26
  27 struct pkcs7_parse_context {
  28         struct pkcs7_message    *msg;           /* Message being constructed */
  29         struct pkcs7_signed_info *sinfo;        /* SignedInfo being constructed */
  30         struct pkcs7_signed_info **ppsinfo;
  31         struct x509_certificate *certs;         /* Certificate cache */
  32         struct x509_certificate **ppcerts;
  33         unsigned long   data;                   /* Start of data */
  34         enum OID        last_oid;               /* Last OID encountered */
  35         unsigned        x509_index;
  36         unsigned        sinfo_index;
  37         const void      *raw_serial;
  38         unsigned        raw_serial_size;
  39         unsigned        raw_issuer_size;
  40         const void      *raw_issuer;
  41         const void      *raw_skid;
  42         unsigned        raw_skid_size;
  43         bool            expect_skid;
  44 };
  45
  46 /*
  47  * Free a signed information block.
  48  */
  49 static void pkcs7_free_signed_info(struct pkcs7_signed_info *sinfo)
  50 {
  51         if (sinfo) {
  52                 public_key_signature_free(sinfo->sig);
  53                 kfree(sinfo);
  54         }
  55 }
  56
  57 /**
  58  * pkcs7_free_message - Free a PKCS#7 message
  59  * @pkcs7: The PKCS#7 message to free
  60  */
  61 void pkcs7_free_message(struct pkcs7_message *pkcs7)
  62 {
  63         struct x509_certificate *cert;
  64         struct pkcs7_signed_info *sinfo;
  65
  66         if (pkcs7) {
  67                 while (pkcs7->certs) {
  68                         cert = pkcs7->certs;
  69                         pkcs7->certs = cert->next;
  70                         x509_free_certificate(cert);
  71                 }
  72                 while (pkcs7->crl) {
  73                         cert = pkcs7->crl;
  74                         pkcs7->crl = cert->next;
  75                         x509_free_certificate(cert);
  76                 }
  77                 while (pkcs7->signed_infos) {
  78                         sinfo = pkcs7->signed_infos;
  79                         pkcs7->signed_infos = sinfo->next;
  80                         pkcs7_free_signed_info(sinfo);
  81                 }
  82                 kfree(pkcs7);
  83         }
  84 }
  85 EXPORT_SYMBOL_GPL(pkcs7_free_message);
  86
  87 /*
  88  * Check authenticatedAttributes are provided or not provided consistently.
  89  */
  90 static int pkcs7_check_authattrs(struct pkcs7_message *msg)
  91 {
  92         struct pkcs7_signed_info *sinfo;
  93         bool want = false;
  94
  95         sinfo = msg->signed_infos;
  96         if (!sinfo)
  97                 goto inconsistent;
  98
  99         if (sinfo->authattrs) {
 100                 want = true;
 101                 msg->have_authattrs = true;
 102         }
 103
 104         for (sinfo = sinfo->next; sinfo; sinfo = sinfo->next)
 105                 if (!!sinfo->authattrs != want)
 106                         goto inconsistent;
 107         return 0;
 108
 109 inconsistent:
 110         pr_warn("Inconsistently supplied authAttrs\n");
 111         return -EINVAL;
 112 }
 113
 114 /**
 115  * pkcs7_parse_message - Parse a PKCS#7 message
 116  * @data: The raw binary ASN.1 encoded message to be parsed
 117  * @datalen: The size of the encoded message
 118  */
 119 struct pkcs7_message *pkcs7_parse_message(const void *data, size_t datalen)
 120 {
 121         struct pkcs7_parse_context *ctx;
 122         struct pkcs7_message *msg = ERR_PTR(-ENOMEM);
 123         int ret;
 124
 125         ctx = kzalloc(sizeof(struct pkcs7_parse_context), GFP_KERNEL);
 126         if (!ctx)
 127                 goto out_no_ctx;
 128         ctx->msg = kzalloc(sizeof(struct pkcs7_message), GFP_KERNEL);
 129         if (!ctx->msg)
 130                 goto out_no_msg;
 131         ctx->sinfo = kzalloc(sizeof(struct pkcs7_signed_info), GFP_KERNEL);
 132         if (!ctx->sinfo)
 133                 goto out_no_sinfo;
 134         ctx->sinfo->sig = kzalloc(sizeof(struct public_key_signature),
 135                                   GFP_KERNEL);
 136         if (!ctx->sinfo->sig)
 137                 goto out_no_sig;
 138
 139         ctx->data = (unsigned long)data;
 140         ctx->ppcerts = &ctx->certs;
 141         ctx->ppsinfo = &ctx->msg->signed_infos;
 142
 143         /* Attempt to decode the signature */
 144         ret = asn1_ber_decoder(&pkcs7_decoder, ctx, data, datalen);
 145         if (ret < 0) {
 146                 msg = ERR_PTR(ret);
 147                 goto out;
 148         }
 149
 150         ret = pkcs7_check_authattrs(ctx->msg);
 151         if (ret < 0) {
 152                 msg = ERR_PTR(ret);
 153                 goto out;
 154         }
 155
 156         msg = ctx->msg;
 157         ctx->msg = NULL;
 158
 159 out:
 160         while (ctx->certs) {
 161                 struct x509_certificate *cert = ctx->certs;
 162                 ctx->certs = cert->next;
 163                 x509_free_certificate(cert);
 164         }
 165 out_no_sig:
 166         pkcs7_free_signed_info(ctx->sinfo);
 167 out_no_sinfo:
 168         pkcs7_free_message(ctx->msg);
 169 out_no_msg:
 170         kfree(ctx);
 171 out_no_ctx:
 172         return msg;
 173 }
 174 EXPORT_SYMBOL_GPL(pkcs7_parse_message);
 175
 176 /**
 177  * pkcs7_get_content_data - Get access to the PKCS#7 content
 178  * @pkcs7: The preparsed PKCS#7 message to access
 179  * @_data: Place to return a pointer to the data
 180  * @_data_len: Place to return the data length
 181  * @_headerlen: Size of ASN.1 header not included in _data
 182  *
 183  * Get access to the data content of the PKCS#7 message.  The size of the
 184  * header of the ASN.1 object that contains it is also provided and can be used
 185  * to adjust *_data and *_data_len to get the entire object.
 186  *
 187  * Returns -ENODATA if the data object was missing from the message.
 188  */
 189 int pkcs7_get_content_data(const struct pkcs7_message *pkcs7,
 190                            const void **_data, size_t *_data_len,
 191                            size_t *_headerlen)
 192 {
 193         if (!pkcs7->data)
 194                 return -ENODATA;
 195
 196         *_data = pkcs7->data;
 197         *_data_len = pkcs7->data_len;
 198         if (_headerlen)
 199                 *_headerlen = pkcs7->data_hdrlen;
 200         return 0;
 201 }
 202 EXPORT_SYMBOL_GPL(pkcs7_get_content_data);
 203
 204 /*
 205  * Note an OID when we find one for later processing when we know how
 206  * to interpret it.
 207  */
 208 int pkcs7_note_OID(void *context, size_t hdrlen,
 209                    unsigned char tag,
 210                    const void *value, size_t vlen)
 211 {
 212         struct pkcs7_parse_context *ctx = context;
 213
 214         ctx->last_oid = look_up_OID(value, vlen);
 215         if (ctx->last_oid == OID__NR) {
 216                 char buffer[50];
 217                 sprint_oid(value, vlen, buffer, sizeof(buffer));
 218                 printk("PKCS7: Unknown OID: [%lu] %s\n",
 219                        (unsigned long)value - ctx->data, buffer);
 220         }
 221         return 0;
 222 }
 223
 224 /*
 225  * Note the digest algorithm for the signature.
 226  */
 227 int pkcs7_sig_note_digest_algo(void *context, size_t hdrlen,
 228                                unsigned char tag,
 229                                const void *value, size_t vlen)
 230 {
 231         struct pkcs7_parse_context *ctx = context;
 232
 233         switch (ctx->last_oid) {
 234         case OID_md4:
 235                 ctx->sinfo->sig->hash_algo = "md4";
 236                 break;
 237         case OID_md5:
 238                 ctx->sinfo->sig->hash_algo = "md5";
 239                 break;
 240         case OID_sha1:
 241                 ctx->sinfo->sig->hash_algo = "sha1";
 242                 break;
 243         case OID_sha256:
 244                 ctx->sinfo->sig->hash_algo = "sha256";
 245                 break;
 246         case OID_sha384:
 247                 ctx->sinfo->sig->hash_algo = "sha384";
 248                 break;
 249         case OID_sha512:
 250                 ctx->sinfo->sig->hash_algo = "sha512";
 251                 break;
 252         case OID_sha224:
 253                 ctx->sinfo->sig->hash_algo = "sha224";
 254                 break;
 255         default:
 256                 printk("Unsupported digest algo: %u\n", ctx->last_oid);
 257                 return -ENOPKG;
 258         }
 259         return 0;
 260 }
 261
 262 /*
 263  * Note the public key algorithm for the signature.
 264  */
 265 int pkcs7_sig_note_pkey_algo(void *context, size_t hdrlen,
 266                              unsigned char tag,
 267                              const void *value, size_t vlen)
 268 {
 269         struct pkcs7_parse_context *ctx = context;
 270
 271         switch (ctx->last_oid) {
 272         case OID_rsaEncryption:
 273                 ctx->sinfo->sig->pkey_algo = "rsa";
 274                 break;
 275         default:
 276                 printk("Unsupported pkey algo: %u\n", ctx->last_oid);
 277                 return -ENOPKG;
 278         }
 279         return 0;
 280 }
 281
 282 /*
 283  * We only support signed data [RFC2315 sec 9].
 284  */
 285 int pkcs7_check_content_type(void *context, size_t hdrlen,
 286                              unsigned char tag,
 287                              const void *value, size_t vlen)
 288 {
 289         struct pkcs7_parse_context *ctx = context;
 290
 291         if (ctx->last_oid != OID_signed_data) {
 292                 pr_warn("Only support pkcs7_signedData type\n");
 293                 return -EINVAL;
 294         }
 295
 296         return 0;
 297 }
 298
 299 /*
 300  * Note the SignedData version
 301  */
 302 int pkcs7_note_signeddata_version(void *context, size_t hdrlen,
 303                                   unsigned char tag,
 304                                   const void *value, size_t vlen)
 305 {
 306         struct pkcs7_parse_context *ctx = context;
 307         unsigned version;
 308
 309         if (vlen != 1)
 310                 goto unsupported;
 311
 312         ctx->msg->version = version = *(const u8 *)value;
 313         switch (version) {
 314         case 1:
 315                 /* PKCS#7 SignedData [RFC2315 sec 9.1]
 316                  * CMS ver 1 SignedData [RFC5652 sec 5.1]
 317                  */
 318                 break;
 319         case 3:
 320                 /* CMS ver 3 SignedData [RFC2315 sec 5.1] */
 321                 break;
 322         default:
 323                 goto unsupported;
 324         }
 325
 326         return 0;
 327
 328 unsupported:
 329         pr_warn("Unsupported SignedData version\n");
 330         return -EINVAL;
 331 }
 332
 333 /*
 334  * Note the SignerInfo version
 335  */
 336 int pkcs7_note_signerinfo_version(void *context, size_t hdrlen,
 337                                   unsigned char tag,
 338                                   const void *value, size_t vlen)
 339 {
 340         struct pkcs7_parse_context *ctx = context;
 341         unsigned version;
 342
 343         if (vlen != 1)
 344                 goto unsupported;
 345
 346         version = *(const u8 *)value;
 347         switch (version) {
 348         case 1:
 349                 /* PKCS#7 SignerInfo [RFC2315 sec 9.2]
 350                  * CMS ver 1 SignerInfo [RFC5652 sec 5.3]
 351                  */
 352                 if (ctx->msg->version != 1)
 353                         goto version_mismatch;
 354                 ctx->expect_skid = false;
 355                 break;
 356         case 3:
 357                 /* CMS ver 3 SignerInfo [RFC2315 sec 5.3] */
 358                 if (ctx->msg->version == 1)
 359                         goto version_mismatch;
 360                 ctx->expect_skid = true;
 361                 break;
 362         default:
 363                 goto unsupported;
 364         }
 365
 366         return 0;
 367
 368 unsupported:
 369         pr_warn("Unsupported SignerInfo version\n");
 370         return -EINVAL;
 371 version_mismatch:
 372         pr_warn("SignedData-SignerInfo version mismatch\n");
 373         return -EBADMSG;
 374 }
 375
 376 /*
 377  * Extract a certificate and store it in the context.
 378  */
 379 int pkcs7_extract_cert(void *context, size_t hdrlen,
 380                        unsigned char tag,
 381                        const void *value, size_t vlen)
 382 {
 383         struct pkcs7_parse_context *ctx = context;
 384         struct x509_certificate *x509;
 385
 386         if (tag != ((ASN1_UNIV << 6) | ASN1_CONS_BIT | ASN1_SEQ)) {
 387                 pr_debug("Cert began with tag %02x at %lu\n",
 388                          tag, (unsigned long)ctx - ctx->data);
 389                 return -EBADMSG;
 390         }
 391
 392         /* We have to correct for the header so that the X.509 parser can start
 393          * from the beginning.  Note that since X.509 stipulates DER, there
 394          * probably shouldn't be an EOC trailer - but it is in PKCS#7 (which
 395          * stipulates BER).
 396          */
 397         value -= hdrlen;
 398         vlen += hdrlen;
 399
 400         if (((u8*)value)[1] == 0x80)
 401                 vlen += 2; /* Indefinite length - there should be an EOC */
 402
 403         x509 = x509_cert_parse(value, vlen);
 404         if (IS_ERR(x509))
 405                 return PTR_ERR(x509);
 406
 407         x509->index = ++ctx->x509_index;
 408         pr_debug("Got cert %u for %s\n", x509->index, x509->subject);
 409         pr_debug("- fingerprint %*phN\n", x509->id->len, x509->id->data);
 410
 411         *ctx->ppcerts = x509;
 412         ctx->ppcerts = &x509->next;
 413         return 0;
 414 }
 415
 416 /*
 417  * Save the certificate list
 418  */
 419 int pkcs7_note_certificate_list(void *context, size_t hdrlen,
 420                                 unsigned char tag,
 421                                 const void *value, size_t vlen)
 422 {
 423         struct pkcs7_parse_context *ctx = context;
 424
 425         pr_devel("Got cert list (%02x)\n", tag);
 426
 427         *ctx->ppcerts = ctx->msg->certs;
 428         ctx->msg->certs = ctx->certs;
 429         ctx->certs = NULL;
 430         ctx->ppcerts = &ctx->certs;
 431         return 0;
 432 }
 433
 434 /*
 435  * Note the content type.
 436  */
 437 int pkcs7_note_content(void *context, size_t hdrlen,
 438                        unsigned char tag,
 439                        const void *value, size_t vlen)
 440 {
 441         struct pkcs7_parse_context *ctx = context;
 442
 443         if (ctx->last_oid != OID_data &&
 444             ctx->last_oid != OID_msIndirectData) {
 445                 pr_warn("Unsupported data type %d\n", ctx->last_oid);
 446                 return -EINVAL;
 447         }
 448
 449         ctx->msg->data_type = ctx->last_oid;
 450         return 0;
 451 }
 452
 453 /*
 454  * Extract the data from the message and store that and its content type OID in
 455  * the context.
 456  */
 457 int pkcs7_note_data(void *context, size_t hdrlen,
 458                     unsigned char tag,
 459                     const void *value, size_t vlen)
 460 {
 461         struct pkcs7_parse_context *ctx = context;
 462
 463         pr_debug("Got data\n");
 464
 465         ctx->msg->data = value;
 466         ctx->msg->data_len = vlen;
 467         ctx->msg->data_hdrlen = hdrlen;
 468         return 0;
 469 }
 470
 471 /*
 472  * Parse authenticated attributes.
 473  */
 474 int pkcs7_sig_note_authenticated_attr(void *context, size_t hdrlen,
 475                                       unsigned char tag,
 476                                       const void *value, size_t vlen)
 477 {
 478         struct pkcs7_parse_context *ctx = context;
 479         struct pkcs7_signed_info *sinfo = ctx->sinfo;
 480         enum OID content_type;
 481
 482         pr_devel("AuthAttr: %02x %zu [%*ph]\n", tag, vlen, (unsigned)vlen, value);
 483
 484         switch (ctx->last_oid) {
 485         case OID_contentType:
 486                 if (__test_and_set_bit(sinfo_has_content_type, &sinfo->aa_set))
 487                         goto repeated;
 488                 content_type = look_up_OID(value, vlen);
 489                 if (content_type != ctx->msg->data_type) {
 490                         pr_warn("Mismatch between global data type (%d) and sinfo %u (%d)\n",
 491                                 ctx->msg->data_type, sinfo->index,
 492                                 content_type);
 493                         return -EBADMSG;
 494                 }
 495                 return 0;
 496
 497         case OID_signingTime:
 498                 if (__test_and_set_bit(sinfo_has_signing_time, &sinfo->aa_set))
 499                         goto repeated;
 500                 /* Should we check that the signing time is consistent
 501                  * with the signer's X.509 cert?
 502                  */
 503                 return x509_decode_time(&sinfo->signing_time,
 504                                         hdrlen, tag, value, vlen);
 505
 506         case OID_messageDigest:
 507                 if (__test_and_set_bit(sinfo_has_message_digest, &sinfo->aa_set))
 508                         goto repeated;
 509                 if (tag != ASN1_OTS)
 510                         return -EBADMSG;
 511                 sinfo->msgdigest = value;
 512                 sinfo->msgdigest_len = vlen;
 513                 return 0;
 514
 515         case OID_smimeCapabilites:
 516                 if (__test_and_set_bit(sinfo_has_smime_caps, &sinfo->aa_set))
 517                         goto repeated;
 518                 if (ctx->msg->data_type != OID_msIndirectData) {
 519                         pr_warn("S/MIME Caps only allowed with Authenticode\n");
 520                         return -EKEYREJECTED;
 521                 }
 522                 return 0;
 523
 524                 /* Microsoft SpOpusInfo seems to be contain cont[0] 16-bit BE
 525                  * char URLs and cont[1] 8-bit char URLs.
 526                  *
 527                  * Microsoft StatementType seems to contain a list of OIDs that
 528                  * are also used as extendedKeyUsage types in X.509 certs.
 529                  */
 530         case OID_msSpOpusInfo:
 531                 if (__test_and_set_bit(sinfo_has_ms_opus_info, &sinfo->aa_set))
 532                         goto repeated;
 533                 goto authenticode_check;
 534         case OID_msStatementType:
 535                 if (__test_and_set_bit(sinfo_has_ms_statement_type, &sinfo->aa_set))
 536                         goto repeated;
 537         authenticode_check:
 538                 if (ctx->msg->data_type != OID_msIndirectData) {
 539                         pr_warn("Authenticode AuthAttrs only allowed with Authenticode\n");
 540                         return -EKEYREJECTED;
 541                 }
 542                 /* I'm not sure how to validate these */
 543                 return 0;
 544         default:
 545                 return 0;
 546         }
 547
 548 repeated:
 549         /* We permit max one item per AuthenticatedAttribute and no repeats */
 550         pr_warn("Repeated/multivalue AuthAttrs not permitted\n");
 551         return -EKEYREJECTED;
 552 }
 553
 554 /*
 555  * Note the set of auth attributes for digestion purposes [RFC2315 sec 9.3]
 556  */
 557 int pkcs7_sig_note_set_of_authattrs(void *context, size_t hdrlen,
 558                                     unsigned char tag,
 559                                     const void *value, size_t vlen)
 560 {
 561         struct pkcs7_parse_context *ctx = context;
 562         struct pkcs7_signed_info *sinfo = ctx->sinfo;
 563
 564         if (!test_bit(sinfo_has_content_type, &sinfo->aa_set) ||
 565             !test_bit(sinfo_has_message_digest, &sinfo->aa_set)) {
 566                 pr_warn("Missing required AuthAttr\n");
 567                 return -EBADMSG;
 568         }
 569
 570         if (ctx->msg->data_type != OID_msIndirectData &&
 571             test_bit(sinfo_has_ms_opus_info, &sinfo->aa_set)) {
 572                 pr_warn("Unexpected Authenticode AuthAttr\n");
 573                 return -EBADMSG;
 574         }
 575
 576         /* We need to switch the 'CONT 0' to a 'SET OF' when we digest */
 577         sinfo->authattrs = value - (hdrlen - 1);
 578         sinfo->authattrs_len = vlen + (hdrlen - 1);
 579         return 0;
 580 }
 581
 582 /*
 583  * Note the issuing certificate serial number
 584  */
 585 int pkcs7_sig_note_serial(void *context, size_t hdrlen,
 586                           unsigned char tag,
 587                           const void *value, size_t vlen)
 588 {
 589         struct pkcs7_parse_context *ctx = context;
 590         ctx->raw_serial = value;
 591         ctx->raw_serial_size = vlen;
 592         return 0;
 593 }
 594
 595 /*
 596  * Note the issuer's name
 597  */
 598 int pkcs7_sig_note_issuer(void *context, size_t hdrlen,
 599                           unsigned char tag,
 600                           const void *value, size_t vlen)
 601 {
 602         struct pkcs7_parse_context *ctx = context;
 603         ctx->raw_issuer = value;
 604         ctx->raw_issuer_size = vlen;
 605         return 0;
 606 }
 607
 608 /*
 609  * Note the issuing cert's subjectKeyIdentifier
 610  */
 611 int pkcs7_sig_note_skid(void *context, size_t hdrlen,
 612                         unsigned char tag,
 613                         const void *value, size_t vlen)
 614 {
 615         struct pkcs7_parse_context *ctx = context;
 616
 617         pr_devel("SKID: %02x %zu [%*ph]\n", tag, vlen, (unsigned)vlen, value);
 618
 619         ctx->raw_skid = value;
 620         ctx->raw_skid_size = vlen;
 621         return 0;
 622 }
 623
 624 /*
 625  * Note the signature data
 626  */
 627 int pkcs7_sig_note_signature(void *context, size_t hdrlen,
 628                              unsigned char tag,
 629                              const void *value, size_t vlen)
 630 {
 631         struct pkcs7_parse_context *ctx = context;
 632
 633         ctx->sinfo->sig->s = kmemdup(value, vlen, GFP_KERNEL);
 634         if (!ctx->sinfo->sig->s)
 635                 return -ENOMEM;
 636
 637         ctx->sinfo->sig->s_size = vlen;
 638         return 0;
 639 }
 640
 641 /*
 642  * Note a signature information block
 643  */
 644 int pkcs7_note_signed_info(void *context, size_t hdrlen,
 645                            unsigned char tag,
 646                            const void *value, size_t vlen)
 647 {
 648         struct pkcs7_parse_context *ctx = context;
 649         struct pkcs7_signed_info *sinfo = ctx->sinfo;
 650         struct asymmetric_key_id *kid;
 651
 652         if (ctx->msg->data_type == OID_msIndirectData && !sinfo->authattrs) {
 653                 pr_warn("Authenticode requires AuthAttrs\n");
 654                 return -EBADMSG;
 655         }
 656
 657         /* Generate cert issuer + serial number key ID */
 658         if (!ctx->expect_skid) {
 659                 kid = asymmetric_key_generate_id(ctx->raw_serial,
 660                                                  ctx->raw_serial_size,
 661                                                  ctx->raw_issuer,
 662                                                  ctx->raw_issuer_size);
 663         } else {
 664                 kid = asymmetric_key_generate_id(ctx->raw_skid,
 665                                                  ctx->raw_skid_size,
 666                                                  "", 0);
 667         }
 668         if (IS_ERR(kid))
 669                 return PTR_ERR(kid);
 670
 671         pr_devel("SINFO KID: %u [%*phN]\n", kid->len, kid->len, kid->data);
 672
 673         sinfo->sig->auth_ids[0] = kid;
 674         sinfo->index = ++ctx->sinfo_index;
 675         *ctx->ppsinfo = sinfo;
 676         ctx->ppsinfo = &sinfo->next;
 677         ctx->sinfo = kzalloc(sizeof(struct pkcs7_signed_info), GFP_KERNEL);
 678         if (!ctx->sinfo)
 679                 return -ENOMEM;
 680         ctx->sinfo->sig = kzalloc(sizeof(struct public_key_signature),
 681                                   GFP_KERNEL);
 682         if (!ctx->sinfo->sig)
 683                 return -ENOMEM;
 684         return 0;
 685 }