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