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