crypto/asymmetric_keys/x509_cert_parser.c

   1 /* X.509 certificate 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) "X.509: "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 "public_key.h"
  19 #include "x509_parser.h"
  20 #include "x509-asn1.h"
  21 #include "x509_akid-asn1.h"
  22 #include "x509_rsakey-asn1.h"
  23
  24 struct x509_parse_context {
  25         struct x509_certificate *cert;          /* Certificate being constructed */
  26         unsigned long   data;                   /* Start of data */
  27         const void      *cert_start;            /* Start of cert content */
  28         const void      *key;                   /* Key data */
  29         size_t          key_size;               /* Size of key data */
  30         enum OID        last_oid;               /* Last OID encountered */
  31         enum OID        algo_oid;               /* Algorithm OID */
  32         unsigned char   nr_mpi;                 /* Number of MPIs stored */
  33         u8              o_size;                 /* Size of organizationName (O) */
  34         u8              cn_size;                /* Size of commonName (CN) */
  35         u8              email_size;             /* Size of emailAddress */
  36         u16             o_offset;               /* Offset of organizationName (O) */
  37         u16             cn_offset;              /* Offset of commonName (CN) */
  38         u16             email_offset;           /* Offset of emailAddress */
  39         unsigned        raw_akid_size;
  40         const void      *raw_akid;              /* Raw authorityKeyId in ASN.1 */
  41         const void      *akid_raw_issuer;       /* Raw directoryName in authorityKeyId */
  42         unsigned        akid_raw_issuer_size;
  43 };
  44
  45 /*
  46  * Free an X.509 certificate
  47  */
  48 void x509_free_certificate(struct x509_certificate *cert)
  49 {
  50         if (cert) {
  51                 public_key_destroy(cert->pub);
  52                 kfree(cert->issuer);
  53                 kfree(cert->subject);
  54                 kfree(cert->id);
  55                 kfree(cert->skid);
  56                 kfree(cert->akid_id);
  57                 kfree(cert->akid_skid);
  58                 kfree(cert->sig.digest);
  59                 mpi_free(cert->sig.rsa.s);
  60                 kfree(cert);
  61         }
  62 }
  63 EXPORT_SYMBOL_GPL(x509_free_certificate);
  64
  65 /*
  66  * Parse an X.509 certificate
  67  */
  68 struct x509_certificate *x509_cert_parse(const void *data, size_t datalen)
  69 {
  70         struct x509_certificate *cert;
  71         struct x509_parse_context *ctx;
  72         struct asymmetric_key_id *kid;
  73         long ret;
  74
  75         ret = -ENOMEM;
  76         cert = kzalloc(sizeof(struct x509_certificate), GFP_KERNEL);
  77         if (!cert)
  78                 goto error_no_cert;
  79         cert->pub = kzalloc(sizeof(struct public_key), GFP_KERNEL);
  80         if (!cert->pub)
  81                 goto error_no_ctx;
  82         ctx = kzalloc(sizeof(struct x509_parse_context), GFP_KERNEL);
  83         if (!ctx)
  84                 goto error_no_ctx;
  85
  86         ctx->cert = cert;
  87         ctx->data = (unsigned long)data;
  88
  89         /* Attempt to decode the certificate */
  90         ret = asn1_ber_decoder(&x509_decoder, ctx, data, datalen);
  91         if (ret < 0)
  92                 goto error_decode;
  93
  94         /* Decode the AuthorityKeyIdentifier */
  95         if (ctx->raw_akid) {
  96                 pr_devel("AKID: %u %*phN\n",
  97                          ctx->raw_akid_size, ctx->raw_akid_size, ctx->raw_akid);
  98                 ret = asn1_ber_decoder(&x509_akid_decoder, ctx,
  99                                        ctx->raw_akid, ctx->raw_akid_size);
 100                 if (ret < 0) {
 101                         pr_warn("Couldn't decode AuthKeyIdentifier\n");
 102                         goto error_decode;
 103                 }
 104         }
 105
 106         /* Decode the public key */
 107         ret = asn1_ber_decoder(&x509_rsakey_decoder, ctx,
 108                                ctx->key, ctx->key_size);
 109         if (ret < 0)
 110                 goto error_decode;
 111
 112         /* Generate cert issuer + serial number key ID */
 113         kid = asymmetric_key_generate_id(cert->raw_serial,
 114                                          cert->raw_serial_size,
 115                                          cert->raw_issuer,
 116                                          cert->raw_issuer_size);
 117         if (IS_ERR(kid)) {
 118                 ret = PTR_ERR(kid);
 119                 goto error_decode;
 120         }
 121         cert->id = kid;
 122
 123         kfree(ctx);
 124         return cert;
 125
 126 error_decode:
 127         kfree(ctx);
 128 error_no_ctx:
 129         x509_free_certificate(cert);
 130 error_no_cert:
 131         return ERR_PTR(ret);
 132 }
 133 EXPORT_SYMBOL_GPL(x509_cert_parse);
 134
 135 /*
 136  * Note an OID when we find one for later processing when we know how
 137  * to interpret it.
 138  */
 139 int x509_note_OID(void *context, size_t hdrlen,
 140              unsigned char tag,
 141              const void *value, size_t vlen)
 142 {
 143         struct x509_parse_context *ctx = context;
 144
 145         ctx->last_oid = look_up_OID(value, vlen);
 146         if (ctx->last_oid == OID__NR) {
 147                 char buffer[50];
 148                 sprint_oid(value, vlen, buffer, sizeof(buffer));
 149                 pr_debug("Unknown OID: [%lu] %s\n",
 150                          (unsigned long)value - ctx->data, buffer);
 151         }
 152         return 0;
 153 }
 154
 155 /*
 156  * Save the position of the TBS data so that we can check the signature over it
 157  * later.
 158  */
 159 int x509_note_tbs_certificate(void *context, size_t hdrlen,
 160                               unsigned char tag,
 161                               const void *value, size_t vlen)
 162 {
 163         struct x509_parse_context *ctx = context;
 164
 165         pr_debug("x509_note_tbs_certificate(,%zu,%02x,%ld,%zu)!\n",
 166                  hdrlen, tag, (unsigned long)value - ctx->data, vlen);
 167
 168         ctx->cert->tbs = value - hdrlen;
 169         ctx->cert->tbs_size = vlen + hdrlen;
 170         return 0;
 171 }
 172
 173 /*
 174  * Record the public key algorithm
 175  */
 176 int x509_note_pkey_algo(void *context, size_t hdrlen,
 177                         unsigned char tag,
 178                         const void *value, size_t vlen)
 179 {
 180         struct x509_parse_context *ctx = context;
 181
 182         pr_debug("PubKey Algo: %u\n", ctx->last_oid);
 183
 184         switch (ctx->last_oid) {
 185         case OID_md2WithRSAEncryption:
 186         case OID_md3WithRSAEncryption:
 187         default:
 188                 return -ENOPKG; /* Unsupported combination */
 189
 190         case OID_md4WithRSAEncryption:
 191                 ctx->cert->sig.pkey_hash_algo = HASH_ALGO_MD5;
 192                 ctx->cert->sig.pkey_algo = PKEY_ALGO_RSA;
 193                 break;
 194
 195         case OID_sha1WithRSAEncryption:
 196                 ctx->cert->sig.pkey_hash_algo = HASH_ALGO_SHA1;
 197                 ctx->cert->sig.pkey_algo = PKEY_ALGO_RSA;
 198                 break;
 199
 200         case OID_sha256WithRSAEncryption:
 201                 ctx->cert->sig.pkey_hash_algo = HASH_ALGO_SHA256;
 202                 ctx->cert->sig.pkey_algo = PKEY_ALGO_RSA;
 203                 break;
 204
 205         case OID_sha384WithRSAEncryption:
 206                 ctx->cert->sig.pkey_hash_algo = HASH_ALGO_SHA384;
 207                 ctx->cert->sig.pkey_algo = PKEY_ALGO_RSA;
 208                 break;
 209
 210         case OID_sha512WithRSAEncryption:
 211                 ctx->cert->sig.pkey_hash_algo = HASH_ALGO_SHA512;
 212                 ctx->cert->sig.pkey_algo = PKEY_ALGO_RSA;
 213                 break;
 214
 215         case OID_sha224WithRSAEncryption:
 216                 ctx->cert->sig.pkey_hash_algo = HASH_ALGO_SHA224;
 217                 ctx->cert->sig.pkey_algo = PKEY_ALGO_RSA;
 218                 break;
 219         }
 220
 221         ctx->algo_oid = ctx->last_oid;
 222         return 0;
 223 }
 224
 225 /*
 226  * Note the whereabouts and type of the signature.
 227  */
 228 int x509_note_signature(void *context, size_t hdrlen,
 229                         unsigned char tag,
 230                         const void *value, size_t vlen)
 231 {
 232         struct x509_parse_context *ctx = context;
 233
 234         pr_debug("Signature type: %u size %zu\n", ctx->last_oid, vlen);
 235
 236         if (ctx->last_oid != ctx->algo_oid) {
 237                 pr_warn("Got cert with pkey (%u) and sig (%u) algorithm OIDs\n",
 238                         ctx->algo_oid, ctx->last_oid);
 239                 return -EINVAL;
 240         }
 241
 242         ctx->cert->raw_sig = value;
 243         ctx->cert->raw_sig_size = vlen;
 244         return 0;
 245 }
 246
 247 /*
 248  * Note the certificate serial number
 249  */
 250 int x509_note_serial(void *context, size_t hdrlen,
 251                      unsigned char tag,
 252                      const void *value, size_t vlen)
 253 {
 254         struct x509_parse_context *ctx = context;
 255         ctx->cert->raw_serial = value;
 256         ctx->cert->raw_serial_size = vlen;
 257         return 0;
 258 }
 259
 260 /*
 261  * Note some of the name segments from which we'll fabricate a name.
 262  */
 263 int x509_extract_name_segment(void *context, size_t hdrlen,
 264                               unsigned char tag,
 265                               const void *value, size_t vlen)
 266 {
 267         struct x509_parse_context *ctx = context;
 268
 269         switch (ctx->last_oid) {
 270         case OID_commonName:
 271                 ctx->cn_size = vlen;
 272                 ctx->cn_offset = (unsigned long)value - ctx->data;
 273                 break;
 274         case OID_organizationName:
 275                 ctx->o_size = vlen;
 276                 ctx->o_offset = (unsigned long)value - ctx->data;
 277                 break;
 278         case OID_email_address:
 279                 ctx->email_size = vlen;
 280                 ctx->email_offset = (unsigned long)value - ctx->data;
 281                 break;
 282         default:
 283                 break;
 284         }
 285
 286         return 0;
 287 }
 288
 289 /*
 290  * Fabricate and save the issuer and subject names
 291  */
 292 static int x509_fabricate_name(struct x509_parse_context *ctx, size_t hdrlen,
 293                                unsigned char tag,
 294                                char **_name, size_t vlen)
 295 {
 296         const void *name, *data = (const void *)ctx->data;
 297         size_t namesize;
 298         char *buffer;
 299
 300         if (*_name)
 301                 return -EINVAL;
 302
 303         /* Empty name string if no material */
 304         if (!ctx->cn_size && !ctx->o_size && !ctx->email_size) {
 305                 buffer = kmalloc(1, GFP_KERNEL);
 306                 if (!buffer)
 307                         return -ENOMEM;
 308                 buffer[0] = 0;
 309                 goto done;
 310         }
 311
 312         if (ctx->cn_size && ctx->o_size) {
 313                 /* Consider combining O and CN, but use only the CN if it is
 314                  * prefixed by the O, or a significant portion thereof.
 315                  */
 316                 namesize = ctx->cn_size;
 317                 name = data + ctx->cn_offset;
 318                 if (ctx->cn_size >= ctx->o_size &&
 319                     memcmp(data + ctx->cn_offset, data + ctx->o_offset,
 320                            ctx->o_size) == 0)
 321                         goto single_component;
 322                 if (ctx->cn_size >= 7 &&
 323                     ctx->o_size >= 7 &&
 324                     memcmp(data + ctx->cn_offset, data + ctx->o_offset, 7) == 0)
 325                         goto single_component;
 326
 327                 buffer = kmalloc(ctx->o_size + 2 + ctx->cn_size + 1,
 328                                  GFP_KERNEL);
 329                 if (!buffer)
 330                         return -ENOMEM;
 331
 332                 memcpy(buffer,
 333                        data + ctx->o_offset, ctx->o_size);
 334                 buffer[ctx->o_size + 0] = ':';
 335                 buffer[ctx->o_size + 1] = ' ';
 336                 memcpy(buffer + ctx->o_size + 2,
 337                        data + ctx->cn_offset, ctx->cn_size);
 338                 buffer[ctx->o_size + 2 + ctx->cn_size] = 0;
 339                 goto done;
 340
 341         } else if (ctx->cn_size) {
 342                 namesize = ctx->cn_size;
 343                 name = data + ctx->cn_offset;
 344         } else if (ctx->o_size) {
 345                 namesize = ctx->o_size;
 346                 name = data + ctx->o_offset;
 347         } else {
 348                 namesize = ctx->email_size;
 349                 name = data + ctx->email_offset;
 350         }
 351
 352 single_component:
 353         buffer = kmalloc(namesize + 1, GFP_KERNEL);
 354         if (!buffer)
 355                 return -ENOMEM;
 356         memcpy(buffer, name, namesize);
 357         buffer[namesize] = 0;
 358
 359 done:
 360         *_name = buffer;
 361         ctx->cn_size = 0;
 362         ctx->o_size = 0;
 363         ctx->email_size = 0;
 364         return 0;
 365 }
 366
 367 int x509_note_issuer(void *context, size_t hdrlen,
 368                      unsigned char tag,
 369                      const void *value, size_t vlen)
 370 {
 371         struct x509_parse_context *ctx = context;
 372         ctx->cert->raw_issuer = value;
 373         ctx->cert->raw_issuer_size = vlen;
 374         return x509_fabricate_name(ctx, hdrlen, tag, &ctx->cert->issuer, vlen);
 375 }
 376
 377 int x509_note_subject(void *context, size_t hdrlen,
 378                       unsigned char tag,
 379                       const void *value, size_t vlen)
 380 {
 381         struct x509_parse_context *ctx = context;
 382         ctx->cert->raw_subject = value;
 383         ctx->cert->raw_subject_size = vlen;
 384         return x509_fabricate_name(ctx, hdrlen, tag, &ctx->cert->subject, vlen);
 385 }
 386
 387 /*
 388  * Extract the data for the public key algorithm
 389  */
 390 int x509_extract_key_data(void *context, size_t hdrlen,
 391                           unsigned char tag,
 392                           const void *value, size_t vlen)
 393 {
 394         struct x509_parse_context *ctx = context;
 395
 396         if (ctx->last_oid != OID_rsaEncryption)
 397                 return -ENOPKG;
 398
 399         ctx->cert->pub->pkey_algo = PKEY_ALGO_RSA;
 400
 401         /* Discard the BIT STRING metadata */
 402         ctx->key = value + 1;
 403         ctx->key_size = vlen - 1;
 404         return 0;
 405 }
 406
 407 /*
 408  * Extract a RSA public key value
 409  */
 410 int rsa_extract_mpi(void *context, size_t hdrlen,
 411                     unsigned char tag,
 412                     const void *value, size_t vlen)
 413 {
 414         struct x509_parse_context *ctx = context;
 415         MPI mpi;
 416
 417         if (ctx->nr_mpi >= ARRAY_SIZE(ctx->cert->pub->mpi)) {
 418                 pr_err("Too many public key MPIs in certificate\n");
 419                 return -EBADMSG;
 420         }
 421
 422         mpi = mpi_read_raw_data(value, vlen);
 423         if (!mpi)
 424                 return -ENOMEM;
 425
 426         ctx->cert->pub->mpi[ctx->nr_mpi++] = mpi;
 427         return 0;
 428 }
 429
 430 /* The keyIdentifier in AuthorityKeyIdentifier SEQUENCE is tag(CONT,PRIM,0) */
 431 #define SEQ_TAG_KEYID (ASN1_CONT << 6)
 432
 433 /*
 434  * Process certificate extensions that are used to qualify the certificate.
 435  */
 436 int x509_process_extension(void *context, size_t hdrlen,
 437                            unsigned char tag,
 438                            const void *value, size_t vlen)
 439 {
 440         struct x509_parse_context *ctx = context;
 441         struct asymmetric_key_id *kid;
 442         const unsigned char *v = value;
 443
 444         pr_debug("Extension: %u\n", ctx->last_oid);
 445
 446         if (ctx->last_oid == OID_subjectKeyIdentifier) {
 447                 /* Get hold of the key fingerprint */
 448                 if (ctx->cert->skid || vlen < 3)
 449                         return -EBADMSG;
 450                 if (v[0] != ASN1_OTS || v[1] != vlen - 2)
 451                         return -EBADMSG;
 452                 v += 2;
 453                 vlen -= 2;
 454
 455                 ctx->cert->raw_skid_size = vlen;
 456                 ctx->cert->raw_skid = v;
 457                 kid = asymmetric_key_generate_id(v, vlen, "", 0);
 458                 if (IS_ERR(kid))
 459                         return PTR_ERR(kid);
 460                 ctx->cert->skid = kid;
 461                 pr_debug("subjkeyid %*phN\n", kid->len, kid->data);
 462                 return 0;
 463         }
 464
 465         if (ctx->last_oid == OID_authorityKeyIdentifier) {
 466                 /* Get hold of the CA key fingerprint */
 467                 ctx->raw_akid = v;
 468                 ctx->raw_akid_size = vlen;
 469                 return 0;
 470         }
 471
 472         return 0;
 473 }
 474
 475 /**
 476  * x509_decode_time - Decode an X.509 time ASN.1 object
 477  * @_t: The time to fill in
 478  * @hdrlen: The length of the object header
 479  * @tag: The object tag
 480  * @value: The object value
 481  * @vlen: The size of the object value
 482  *
 483  * Decode an ASN.1 universal time or generalised time field into a struct the
 484  * kernel can handle and check it for validity.  The time is decoded thus:
 485  *
 486  *      [RFC5280 §4.1.2.5]
 487  *      CAs conforming to this profile MUST always encode certificate validity
 488  *      dates through the year 2049 as UTCTime; certificate validity dates in
 489  *      2050 or later MUST be encoded as GeneralizedTime.  Conforming
 490  *      applications MUST be able to process validity dates that are encoded in
 491  *      either UTCTime or GeneralizedTime.
 492  */
 493 int x509_decode_time(time64_t *_t,  size_t hdrlen,
 494                      unsigned char tag,
 495                      const unsigned char *value, size_t vlen)
 496 {
 497         static const unsigned char month_lengths[] = { 31, 29, 31, 30, 31, 30,
 498                                                        31, 31, 30, 31, 30, 31 };
 499         const unsigned char *p = value;
 500         unsigned year, mon, day, hour, min, sec, mon_len;
 501
 502 #define dec2bin(X) ({ unsigned char x = (X) - '0'; if (x > 9) goto invalid_time; x; })
 503 #define DD2bin(P) ({ unsigned x = dec2bin(P[0]) * 10 + dec2bin(P[1]); P += 2; x; })
 504
 505         if (tag == ASN1_UNITIM) {
 506                 /* UTCTime: YYMMDDHHMMSSZ */
 507                 if (vlen != 13)
 508                         goto unsupported_time;
 509                 year = DD2bin(p);
 510                 if (year >= 50)
 511                         year += 1900;
 512                 else
 513                         year += 2000;
 514         } else if (tag == ASN1_GENTIM) {
 515                 /* GenTime: YYYYMMDDHHMMSSZ */
 516                 if (vlen != 15)
 517                         goto unsupported_time;
 518                 year = DD2bin(p) * 100 + DD2bin(p);
 519                 if (year >= 1950 && year <= 2049)
 520                         goto invalid_time;
 521         } else {
 522                 goto unsupported_time;
 523         }
 524
 525         mon  = DD2bin(p);
 526         day = DD2bin(p);
 527         hour = DD2bin(p);
 528         min  = DD2bin(p);
 529         sec  = DD2bin(p);
 530
 531         if (*p != 'Z')
 532                 goto unsupported_time;
 533
 534         if (year < 1970 ||
 535             mon < 1 || mon > 12)
 536                 goto invalid_time;
 537
 538         mon_len = month_lengths[mon - 1];
 539         if (mon == 2) {
 540                 if (year % 4 == 0) {
 541                         mon_len = 29;
 542                         if (year % 100 == 0) {
 543                                 year /= 100;
 544                                 if (year % 4 != 0)
 545                                         mon_len = 28;
 546                         }
 547                 }
 548         }
 549
 550         if (day < 1 || day > mon_len ||
 551             hour > 23 ||
 552             min > 59 ||
 553             sec > 59)
 554                 goto invalid_time;
 555
 556         *_t = mktime64(year, mon, day, hour, min, sec);
 557         return 0;
 558
 559 unsupported_time:
 560         pr_debug("Got unsupported time [tag %02x]: '%*phN'\n",
 561                  tag, (int)vlen, value);
 562         return -EBADMSG;
 563 invalid_time:
 564         pr_debug("Got invalid time [tag %02x]: '%*phN'\n",
 565                  tag, (int)vlen, value);
 566         return -EBADMSG;
 567 }
 568 EXPORT_SYMBOL_GPL(x509_decode_time);
 569
 570 int x509_note_not_before(void *context, size_t hdrlen,
 571                          unsigned char tag,
 572                          const void *value, size_t vlen)
 573 {
 574         struct x509_parse_context *ctx = context;
 575         return x509_decode_time(&ctx->cert->valid_from, hdrlen, tag, value, vlen);
 576 }
 577
 578 int x509_note_not_after(void *context, size_t hdrlen,
 579                         unsigned char tag,
 580                         const void *value, size_t vlen)
 581 {
 582         struct x509_parse_context *ctx = context;
 583         return x509_decode_time(&ctx->cert->valid_to, hdrlen, tag, value, vlen);
 584 }
 585
 586 /*
 587  * Note a key identifier-based AuthorityKeyIdentifier
 588  */
 589 int x509_akid_note_kid(void *context, size_t hdrlen,
 590                        unsigned char tag,
 591                        const void *value, size_t vlen)
 592 {
 593         struct x509_parse_context *ctx = context;
 594         struct asymmetric_key_id *kid;
 595
 596         pr_debug("AKID: keyid: %*phN\n", (int)vlen, value);
 597
 598         if (ctx->cert->akid_skid)
 599                 return 0;
 600
 601         kid = asymmetric_key_generate_id(value, vlen, "", 0);
 602         if (IS_ERR(kid))
 603                 return PTR_ERR(kid);
 604         pr_debug("authkeyid %*phN\n", kid->len, kid->data);
 605         ctx->cert->akid_skid = kid;
 606         return 0;
 607 }
 608
 609 /*
 610  * Note a directoryName in an AuthorityKeyIdentifier
 611  */
 612 int x509_akid_note_name(void *context, size_t hdrlen,
 613                         unsigned char tag,
 614                         const void *value, size_t vlen)
 615 {
 616         struct x509_parse_context *ctx = context;
 617
 618         pr_debug("AKID: name: %*phN\n", (int)vlen, value);
 619
 620         ctx->akid_raw_issuer = value;
 621         ctx->akid_raw_issuer_size = vlen;
 622         return 0;
 623 }
 624
 625 /*
 626  * Note a serial number in an AuthorityKeyIdentifier
 627  */
 628 int x509_akid_note_serial(void *context, size_t hdrlen,
 629                           unsigned char tag,
 630                           const void *value, size_t vlen)
 631 {
 632         struct x509_parse_context *ctx = context;
 633         struct asymmetric_key_id *kid;
 634
 635         pr_debug("AKID: serial: %*phN\n", (int)vlen, value);
 636
 637         if (!ctx->akid_raw_issuer || ctx->cert->akid_id)
 638                 return 0;
 639
 640         kid = asymmetric_key_generate_id(value,
 641                                          vlen,
 642                                          ctx->akid_raw_issuer,
 643                                          ctx->akid_raw_issuer_size);
 644         if (IS_ERR(kid))
 645                 return PTR_ERR(kid);
 646
 647         pr_debug("authkeyid %*phN\n", kid->len, kid->data);
 648         ctx->cert->akid_id = kid;
 649         return 0;
 650 }