crypto/asymmetric_keys/pkcs7_parser.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* PKCS#7 parser
   3  *
   4  * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
   5  * Written by David Howells (dhowells@redhat.com)
   6  */
   7
   8 #define pr_fmt(fmt) "PKCS7: "fmt
   9 #include <linux/kernel.h>
  10 #include <linux/module.h>
  11 #include <linux/export.h>
  12 #include <linux/slab.h>
  13 #include <linux/err.h>
  14 #include <linux/oid_registry.h>
  15 #include <crypto/public_key.h>
  16 #include "pkcs7_parser.h"
  17 #include "pkcs7.asn1.h"
  18
  19 MODULE_DESCRIPTION("PKCS#7 parser");
  20 MODULE_AUTHOR("Red Hat, Inc.");
  21 MODULE_LICENSE("GPL");
  22
  23 struct pkcs7_parse_context {
  24         struct pkcs7_message    *msg;           /* Message being constructed */
  25         struct pkcs7_signed_info *sinfo;        /* SignedInfo being constructed */
  26         struct pkcs7_signed_info **ppsinfo;
  27         struct x509_certificate *certs;         /* Certificate cache */
  28         struct x509_certificate **ppcerts;
  29         unsigned long   data;                   /* Start of data */
  30         enum OID        last_oid;               /* Last OID encountered */
  31         unsigned        x509_index;
  32         unsigned        sinfo_index;
  33         const void      *raw_serial;
  34         unsigned        raw_serial_size;
  35         unsigned        raw_issuer_size;
  36         const void      *raw_issuer;
  37         const void      *raw_skid;
  38         unsigned        raw_skid_size;
  39         bool            expect_skid;
  40 };
  41
  42 /*
  43  * Free a signed information block.
  44  */
  45 static void pkcs7_free_signed_info(struct pkcs7_signed_info *sinfo)
  46 {
  47         if (sinfo) {
  48                 public_key_signature_free(sinfo->sig);
  49                 kfree(sinfo);
  50         }
  51 }
  52
  53 /**
  54  * pkcs7_free_message - Free a PKCS#7 message
  55  * @pkcs7: The PKCS#7 message to free
  56  */
  57 void pkcs7_free_message(struct pkcs7_message *pkcs7)
  58 {
  59         struct x509_certificate *cert;
  60         struct pkcs7_signed_info *sinfo;
  61
  62         if (pkcs7) {
  63                 while (pkcs7->certs) {
  64                         cert = pkcs7->certs;
  65                         pkcs7->certs = cert->next;
  66                         x509_free_certificate(cert);
  67                 }
  68                 while (pkcs7->crl) {
  69                         cert = pkcs7->crl;
  70                         pkcs7->crl = cert->next;
  71                         x509_free_certificate(cert);
  72                 }
  73                 while (pkcs7->signed_infos) {
  74                         sinfo = pkcs7->signed_infos;
  75                         pkcs7->signed_infos = sinfo->next;
  76                         pkcs7_free_signed_info(sinfo);
  77                 }
  78                 kfree(pkcs7);
  79         }
  80 }
  81 EXPORT_SYMBOL_GPL(pkcs7_free_message);
  82
  83 /*
  84  * Check authenticatedAttributes are provided or not provided consistently.
  85  */
  86 static int pkcs7_check_authattrs(struct pkcs7_message *msg)
  87 {
  88         struct pkcs7_signed_info *sinfo;
  89         bool want = false;
  90
  91         sinfo = msg->signed_infos;
  92         if (!sinfo)
  93                 goto inconsistent;
  94
  95         if (sinfo->authattrs) {
  96                 want = true;
  97                 msg->have_authattrs = true;
  98         }
  99
 100         for (sinfo = sinfo->next; sinfo; sinfo = sinfo->next)
 101                 if (!!sinfo->authattrs != want)
 102                         goto inconsistent;
 103         return 0;
 104
 105 inconsistent:
 106         pr_warn("Inconsistently supplied authAttrs\n");
 107         return -EINVAL;
 108 }
 109
 110 /**
 111  * pkcs7_parse_message - Parse a PKCS#7 message
 112  * @data: The raw binary ASN.1 encoded message to be parsed
 113  * @datalen: The size of the encoded message
 114  */
 115 struct pkcs7_message *pkcs7_parse_message(const void *data, size_t datalen)
 116 {
 117         struct pkcs7_parse_context *ctx;
 118         struct pkcs7_message *msg = ERR_PTR(-ENOMEM);
 119         int ret;
 120
 121         ctx = kzalloc(sizeof(struct pkcs7_parse_context), GFP_KERNEL);
 122         if (!ctx)
 123                 goto out_no_ctx;
 124         ctx->msg = kzalloc(sizeof(struct pkcs7_message), GFP_KERNEL);
 125         if (!ctx->msg)
 126                 goto out_no_msg;
 127         ctx->sinfo = kzalloc(sizeof(struct pkcs7_signed_info), GFP_KERNEL);
 128         if (!ctx->sinfo)
 129                 goto out_no_sinfo;
 130         ctx->sinfo->sig = kzalloc(sizeof(struct public_key_signature),
 131                                   GFP_KERNEL);
 132         if (!ctx->sinfo->sig)
 133                 goto out_no_sig;
 134
 135         ctx->data = (unsigned long)data;
 136         ctx->ppcerts = &ctx->certs;
 137         ctx->ppsinfo = &ctx->msg->signed_infos;
 138
 139         /* Attempt to decode the signature */
 140         ret = asn1_ber_decoder(&pkcs7_decoder, ctx, data, datalen);
 141         if (ret < 0) {
 142                 msg = ERR_PTR(ret);
 143                 goto out;
 144         }
 145
 146         ret = pkcs7_check_authattrs(ctx->msg);
 147         if (ret < 0) {
 148                 msg = ERR_PTR(ret);
 149                 goto out;
 150         }
 151
 152         msg = ctx->msg;
 153         ctx->msg = NULL;
 154
 155 out:
 156         while (ctx->certs) {
 157                 struct x509_certificate *cert = ctx->certs;
 158                 ctx->certs = cert->next;
 159                 x509_free_certificate(cert);
 160         }
 161 out_no_sig:
 162         pkcs7_free_signed_info(ctx->sinfo);
 163 out_no_sinfo:
 164         pkcs7_free_message(ctx->msg);
 165 out_no_msg:
 166         kfree(ctx);
 167 out_no_ctx:
 168         return msg;
 169 }
 170 EXPORT_SYMBOL_GPL(pkcs7_parse_message);
 171
 172 /**
 173  * pkcs7_get_content_data - Get access to the PKCS#7 content
 174  * @pkcs7: The preparsed PKCS#7 message to access
 175  * @_data: Place to return a pointer to the data
 176  * @_data_len: Place to return the data length
 177  * @_headerlen: Size of ASN.1 header not included in _data
 178  *
 179  * Get access to the data content of the PKCS#7 message.  The size of the
 180  * header of the ASN.1 object that contains it is also provided and can be used
 181  * to adjust *_data and *_data_len to get the entire object.
 182  *
 183  * Returns -ENODATA if the data object was missing from the message.
 184  */
 185 int pkcs7_get_content_data(const struct pkcs7_message *pkcs7,
 186                            const void **_data, size_t *_data_len,
 187                            size_t *_headerlen)
 188 {
 189         if (!pkcs7->data)
 190                 return -ENODATA;
 191
 192         *_data = pkcs7->data;
 193         *_data_len = pkcs7->data_len;
 194         if (_headerlen)
 195                 *_headerlen = pkcs7->data_hdrlen;
 196         return 0;
 197 }
 198 EXPORT_SYMBOL_GPL(pkcs7_get_content_data);
 199
 200 /*
 201  * Note an OID when we find one for later processing when we know how
 202  * to interpret it.
 203  */
 204 int pkcs7_note_OID(void *context, size_t hdrlen,
 205                    unsigned char tag,
 206                    const void *value, size_t vlen)
 207 {
 208         struct pkcs7_parse_context *ctx = context;
 209
 210         ctx->last_oid = look_up_OID(value, vlen);
 211         if (ctx->last_oid == OID__NR) {
 212                 char buffer[50];
 213                 sprint_oid(value, vlen, buffer, sizeof(buffer));
 214                 printk("PKCS7: Unknown OID: [%lu] %s\n",
 215                        (unsigned long)value - ctx->data, buffer);
 216         }
 217         return 0;
 218 }
 219
 220 /*
 221  * Note the digest algorithm for the signature.
 222  */
 223 int pkcs7_sig_note_digest_algo(void *context, size_t hdrlen,
 224                                unsigned char tag,
 225                                const void *value, size_t vlen)
 226 {
 227         struct pkcs7_parse_context *ctx = context;
 228
 229         switch (ctx->last_oid) {
 230         case OID_md4:
 231                 ctx->sinfo->sig->hash_algo = "md4";
 232                 break;
 233         case OID_md5:
 234                 ctx->sinfo->sig->hash_algo = "md5";
 235                 break;
 236         case OID_sha1:
 237                 ctx->sinfo->sig->hash_algo = "sha1";
 238                 break;
 239         case OID_sha256:
 240                 ctx->sinfo->sig->hash_algo = "sha256";
 241                 break;
 242         case OID_sha384:
 243                 ctx->sinfo->sig->hash_algo = "sha384";
 244                 break;
 245         case OID_sha512:
 246                 ctx->sinfo->sig->hash_algo = "sha512";
 247                 break;
 248         case OID_sha224:
 249                 ctx->sinfo->sig->hash_algo = "sha224";
 250                 break;
 251         default:
 252                 printk("Unsupported digest algo: %u\n", ctx->last_oid);
 253                 return -ENOPKG;
 254         }
 255         return 0;
 256 }
 257
 258 /*
 259  * Note the public key algorithm for the signature.
 260  */
 261 int pkcs7_sig_note_pkey_algo(void *context, size_t hdrlen,
 262                              unsigned char tag,
 263                              const void *value, size_t vlen)
 264 {
 265         struct pkcs7_parse_context *ctx = context;
 266
 267         switch (ctx->last_oid) {
 268         case OID_rsaEncryption:
 269                 ctx->sinfo->sig->pkey_algo = "rsa";
 270                 ctx->sinfo->sig->encoding = "pkcs1";
 271                 break;
 272         default:
 273                 printk("Unsupported pkey algo: %u\n", ctx->last_oid);
 274                 return -ENOPKG;
 275         }
 276         return 0;
 277 }
 278
 279 /*
 280  * We only support signed data [RFC2315 sec 9].
 281  */
 282 int pkcs7_check_content_type(void *context, size_t hdrlen,
 283                              unsigned char tag,
 284                              const void *value, size_t vlen)
 285 {
 286         struct pkcs7_parse_context *ctx = context;
 287
 288         if (ctx->last_oid != OID_signed_data) {
 289                 pr_warn("Only support pkcs7_signedData type\n");
 290                 return -EINVAL;
 291         }
 292
 293         return 0;
 294 }
 295
 296 /*
 297  * Note the SignedData version
 298  */
 299 int pkcs7_note_signeddata_version(void *context, size_t hdrlen,
 300                                   unsigned char tag,
 301                                   const void *value, size_t vlen)
 302 {
 303         struct pkcs7_parse_context *ctx = context;
 304         unsigned version;
 305
 306         if (vlen != 1)
 307                 goto unsupported;
 308
 309         ctx->msg->version = version = *(const u8 *)value;
 310         switch (version) {
 311         case 1:
 312                 /* PKCS#7 SignedData [RFC2315 sec 9.1]
 313                  * CMS ver 1 SignedData [RFC5652 sec 5.1]
 314                  */
 315                 break;
 316         case 3:
 317                 /* CMS ver 3 SignedData [RFC2315 sec 5.1] */
 318                 break;
 319         default:
 320                 goto unsupported;
 321         }
 322
 323         return 0;
 324
 325 unsupported:
 326         pr_warn("Unsupported SignedData version\n");
 327         return -EINVAL;
 328 }
 329
 330 /*
 331  * Note the SignerInfo version
 332  */
 333 int pkcs7_note_signerinfo_version(void *context, size_t hdrlen,
 334                                   unsigned char tag,
 335                                   const void *value, size_t vlen)
 336 {
 337         struct pkcs7_parse_context *ctx = context;
 338         unsigned version;
 339
 340         if (vlen != 1)
 341                 goto unsupported;
 342
 343         version = *(const u8 *)value;
 344         switch (version) {
 345         case 1:
 346                 /* PKCS#7 SignerInfo [RFC2315 sec 9.2]
 347                  * CMS ver 1 SignerInfo [RFC5652 sec 5.3]
 348                  */
 349                 if (ctx->msg->version != 1)
 350                         goto version_mismatch;
 351                 ctx->expect_skid = false;
 352                 break;
 353         case 3:
 354                 /* CMS ver 3 SignerInfo [RFC2315 sec 5.3] */
 355                 if (ctx->msg->version == 1)
 356                         goto version_mismatch;
 357                 ctx->expect_skid = true;
 358                 break;
 359         default:
 360                 goto unsupported;
 361         }
 362
 363         return 0;
 364
 365 unsupported:
 366         pr_warn("Unsupported SignerInfo version\n");
 367         return -EINVAL;
 368 version_mismatch:
 369         pr_warn("SignedData-SignerInfo version mismatch\n");
 370         return -EBADMSG;
 371 }
 372
 373 /*
 374  * Extract a certificate and store it in the context.
 375  */
 376 int pkcs7_extract_cert(void *context, size_t hdrlen,
 377                        unsigned char tag,
 378                        const void *value, size_t vlen)
 379 {
 380         struct pkcs7_parse_context *ctx = context;
 381         struct x509_certificate *x509;
 382
 383         if (tag != ((ASN1_UNIV << 6) | ASN1_CONS_BIT | ASN1_SEQ)) {
 384                 pr_debug("Cert began with tag %02x at %lu\n",
 385                          tag, (unsigned long)ctx - ctx->data);
 386                 return -EBADMSG;
 387         }
 388
 389         /* We have to correct for the header so that the X.509 parser can start
 390          * from the beginning.  Note that since X.509 stipulates DER, there
 391          * probably shouldn't be an EOC trailer - but it is in PKCS#7 (which
 392          * stipulates BER).
 393          */
 394         value -= hdrlen;
 395         vlen += hdrlen;
 396
 397         if (((u8*)value)[1] == 0x80)
 398                 vlen += 2; /* Indefinite length - there should be an EOC */
 399
 400         x509 = x509_cert_parse(value, vlen);
 401         if (IS_ERR(x509))
 402                 return PTR_ERR(x509);
 403
 404         x509->index = ++ctx->x509_index;
 405         pr_debug("Got cert %u for %s\n", x509->index, x509->subject);
 406         pr_debug("- fingerprint %*phN\n", x509->id->len, x509->id->data);
 407
 408         *ctx->ppcerts = x509;
 409         ctx->ppcerts = &x509->next;
 410         return 0;
 411 }
 412
 413 /*
 414  * Save the certificate list
 415  */
 416 int pkcs7_note_certificate_list(void *context, size_t hdrlen,
 417                                 unsigned char tag,
 418                                 const void *value, size_t vlen)
 419 {
 420         struct pkcs7_parse_context *ctx = context;
 421
 422         pr_devel("Got cert list (%02x)\n", tag);
 423
 424         *ctx->ppcerts = ctx->msg->certs;
 425         ctx->msg->certs = ctx->certs;
 426         ctx->certs = NULL;
 427         ctx->ppcerts = &ctx->certs;
 428         return 0;
 429 }
 430
 431 /*
 432  * Note the content type.
 433  */
 434 int pkcs7_note_content(void *context, size_t hdrlen,
 435                        unsigned char tag,
 436                        const void *value, size_t vlen)
 437 {
 438         struct pkcs7_parse_context *ctx = context;
 439
 440         if (ctx->last_oid != OID_data &&
 441             ctx->last_oid != OID_msIndirectData) {
 442                 pr_warn("Unsupported data type %d\n", ctx->last_oid);
 443                 return -EINVAL;
 444         }
 445
 446         ctx->msg->data_type = ctx->last_oid;
 447         return 0;
 448 }
 449
 450 /*
 451  * Extract the data from the message and store that and its content type OID in
 452  * the context.
 453  */
 454 int pkcs7_note_data(void *context, size_t hdrlen,
 455                     unsigned char tag,
 456                     const void *value, size_t vlen)
 457 {
 458         struct pkcs7_parse_context *ctx = context;
 459
 460         pr_debug("Got data\n");
 461
 462         ctx->msg->data = value;
 463         ctx->msg->data_len = vlen;
 464         ctx->msg->data_hdrlen = hdrlen;
 465         return 0;
 466 }
 467
 468 /*
 469  * Parse authenticated attributes.
 470  */
 471 int pkcs7_sig_note_authenticated_attr(void *context, size_t hdrlen,
 472                                       unsigned char tag,
 473                                       const void *value, size_t vlen)
 474 {
 475         struct pkcs7_parse_context *ctx = context;
 476         struct pkcs7_signed_info *sinfo = ctx->sinfo;
 477         enum OID content_type;
 478
 479         pr_devel("AuthAttr: %02x %zu [%*ph]\n", tag, vlen, (unsigned)vlen, value);
 480
 481         switch (ctx->last_oid) {
 482         case OID_contentType:
 483                 if (__test_and_set_bit(sinfo_has_content_type, &sinfo->aa_set))
 484                         goto repeated;
 485                 content_type = look_up_OID(value, vlen);
 486                 if (content_type != ctx->msg->data_type) {
 487                         pr_warn("Mismatch between global data type (%d) and sinfo %u (%d)\n",
 488                                 ctx->msg->data_type, sinfo->index,
 489                                 content_type);
 490                         return -EBADMSG;
 491                 }
 492                 return 0;
 493
 494         case OID_signingTime:
 495                 if (__test_and_set_bit(sinfo_has_signing_time, &sinfo->aa_set))
 496                         goto repeated;
 497                 /* Should we check that the signing time is consistent
 498                  * with the signer's X.509 cert?
 499                  */
 500                 return x509_decode_time(&sinfo->signing_time,
 501                                         hdrlen, tag, value, vlen);
 502
 503         case OID_messageDigest:
 504                 if (__test_and_set_bit(sinfo_has_message_digest, &sinfo->aa_set))
 505                         goto repeated;
 506                 if (tag != ASN1_OTS)
 507                         return -EBADMSG;
 508                 sinfo->msgdigest = value;
 509                 sinfo->msgdigest_len = vlen;
 510                 return 0;
 511
 512         case OID_smimeCapabilites:
 513                 if (__test_and_set_bit(sinfo_has_smime_caps, &sinfo->aa_set))
 514                         goto repeated;
 515                 if (ctx->msg->data_type != OID_msIndirectData) {
 516                         pr_warn("S/MIME Caps only allowed with Authenticode\n");
 517                         return -EKEYREJECTED;
 518                 }
 519                 return 0;
 520
 521                 /* Microsoft SpOpusInfo seems to be contain cont[0] 16-bit BE
 522                  * char URLs and cont[1] 8-bit char URLs.
 523                  *
 524                  * Microsoft StatementType seems to contain a list of OIDs that
 525                  * are also used as extendedKeyUsage types in X.509 certs.
 526                  */
 527         case OID_msSpOpusInfo:
 528                 if (__test_and_set_bit(sinfo_has_ms_opus_info, &sinfo->aa_set))
 529                         goto repeated;
 530                 goto authenticode_check;
 531         case OID_msStatementType:
 532                 if (__test_and_set_bit(sinfo_has_ms_statement_type, &sinfo->aa_set))
 533                         goto repeated;
 534         authenticode_check:
 535                 if (ctx->msg->data_type != OID_msIndirectData) {
 536                         pr_warn("Authenticode AuthAttrs only allowed with Authenticode\n");
 537                         return -EKEYREJECTED;
 538                 }
 539                 /* I'm not sure how to validate these */
 540                 return 0;
 541         default:
 542                 return 0;
 543         }
 544
 545 repeated:
 546         /* We permit max one item per AuthenticatedAttribute and no repeats */
 547         pr_warn("Repeated/multivalue AuthAttrs not permitted\n");
 548         return -EKEYREJECTED;
 549 }
 550
 551 /*
 552  * Note the set of auth attributes for digestion purposes [RFC2315 sec 9.3]
 553  */
 554 int pkcs7_sig_note_set_of_authattrs(void *context, size_t hdrlen,
 555                                     unsigned char tag,
 556                                     const void *value, size_t vlen)
 557 {
 558         struct pkcs7_parse_context *ctx = context;
 559         struct pkcs7_signed_info *sinfo = ctx->sinfo;
 560
 561         if (!test_bit(sinfo_has_content_type, &sinfo->aa_set) ||
 562             !test_bit(sinfo_has_message_digest, &sinfo->aa_set)) {
 563                 pr_warn("Missing required AuthAttr\n");
 564                 return -EBADMSG;
 565         }
 566
 567         if (ctx->msg->data_type != OID_msIndirectData &&
 568             test_bit(sinfo_has_ms_opus_info, &sinfo->aa_set)) {
 569                 pr_warn("Unexpected Authenticode AuthAttr\n");
 570                 return -EBADMSG;
 571         }
 572
 573         /* We need to switch the 'CONT 0' to a 'SET OF' when we digest */
 574         sinfo->authattrs = value - (hdrlen - 1);
 575         sinfo->authattrs_len = vlen + (hdrlen - 1);
 576         return 0;
 577 }
 578
 579 /*
 580  * Note the issuing certificate serial number
 581  */
 582 int pkcs7_sig_note_serial(void *context, size_t hdrlen,
 583                           unsigned char tag,
 584                           const void *value, size_t vlen)
 585 {
 586         struct pkcs7_parse_context *ctx = context;
 587         ctx->raw_serial = value;
 588         ctx->raw_serial_size = vlen;
 589         return 0;
 590 }
 591
 592 /*
 593  * Note the issuer's name
 594  */
 595 int pkcs7_sig_note_issuer(void *context, size_t hdrlen,
 596                           unsigned char tag,
 597                           const void *value, size_t vlen)
 598 {
 599         struct pkcs7_parse_context *ctx = context;
 600         ctx->raw_issuer = value;
 601         ctx->raw_issuer_size = vlen;
 602         return 0;
 603 }
 604
 605 /*
 606  * Note the issuing cert's subjectKeyIdentifier
 607  */
 608 int pkcs7_sig_note_skid(void *context, size_t hdrlen,
 609                         unsigned char tag,
 610                         const void *value, size_t vlen)
 611 {
 612         struct pkcs7_parse_context *ctx = context;
 613
 614         pr_devel("SKID: %02x %zu [%*ph]\n", tag, vlen, (unsigned)vlen, value);
 615
 616         ctx->raw_skid = value;
 617         ctx->raw_skid_size = vlen;
 618         return 0;
 619 }
 620
 621 /*
 622  * Note the signature data
 623  */
 624 int pkcs7_sig_note_signature(void *context, size_t hdrlen,
 625                              unsigned char tag,
 626                              const void *value, size_t vlen)
 627 {
 628         struct pkcs7_parse_context *ctx = context;
 629
 630         ctx->sinfo->sig->s = kmemdup(value, vlen, GFP_KERNEL);
 631         if (!ctx->sinfo->sig->s)
 632                 return -ENOMEM;
 633
 634         ctx->sinfo->sig->s_size = vlen;
 635         return 0;
 636 }
 637
 638 /*
 639  * Note a signature information block
 640  */
 641 int pkcs7_note_signed_info(void *context, size_t hdrlen,
 642                            unsigned char tag,
 643                            const void *value, size_t vlen)
 644 {
 645         struct pkcs7_parse_context *ctx = context;
 646         struct pkcs7_signed_info *sinfo = ctx->sinfo;
 647         struct asymmetric_key_id *kid;
 648
 649         if (ctx->msg->data_type == OID_msIndirectData && !sinfo->authattrs) {
 650                 pr_warn("Authenticode requires AuthAttrs\n");
 651                 return -EBADMSG;
 652         }
 653
 654         /* Generate cert issuer + serial number key ID */
 655         if (!ctx->expect_skid) {
 656                 kid = asymmetric_key_generate_id(ctx->raw_serial,
 657                                                  ctx->raw_serial_size,
 658                                                  ctx->raw_issuer,
 659                                                  ctx->raw_issuer_size);
 660         } else {
 661                 kid = asymmetric_key_generate_id(ctx->raw_skid,
 662                                                  ctx->raw_skid_size,
 663                                                  "", 0);
 664         }
 665         if (IS_ERR(kid))
 666                 return PTR_ERR(kid);
 667
 668         pr_devel("SINFO KID: %u [%*phN]\n", kid->len, kid->len, kid->data);
 669
 670         sinfo->sig->auth_ids[0] = kid;
 671         sinfo->index = ++ctx->sinfo_index;
 672         *ctx->ppsinfo = sinfo;
 673         ctx->ppsinfo = &sinfo->next;
 674         ctx->sinfo = kzalloc(sizeof(struct pkcs7_signed_info), GFP_KERNEL);
 675         if (!ctx->sinfo)
 676                 return -ENOMEM;
 677         ctx->sinfo->sig = kzalloc(sizeof(struct public_key_signature),
 678                                   GFP_KERNEL);
 679         if (!ctx->sinfo->sig)
 680                 return -ENOMEM;
 681         return 0;
 682 }