crypto/x509/v3_ncons.c

   1 /*
   2  * Copyright 2003-2023 The OpenSSL Project Authors. All Rights Reserved.
   3  *
   4  * Licensed under the Apache License 2.0 (the "License").  You may not use
   5  * this file except in compliance with the License.  You can obtain a copy
   6  * in the file LICENSE in the source distribution or at
   7  * https://www.openssl.org/source/license.html
   8  */
   9
  10 #include "internal/cryptlib.h"
  11 #include "internal/numbers.h"
  12 #include "internal/safe_math.h"
  13 #include <stdio.h>
  14 #include "crypto/asn1.h"
  15 #include <openssl/asn1t.h>
  16 #include <openssl/conf.h>
  17 #include <openssl/x509v3.h>
  18 #include <openssl/bn.h>
  19
  20 #include "crypto/x509.h"
  21 #include "crypto/punycode.h"
  22 #include "ext_dat.h"
  23
  24 OSSL_SAFE_MATH_SIGNED(int, int)
  25
  26 static void *v2i_NAME_CONSTRAINTS(const X509V3_EXT_METHOD *method,
  27                                   X509V3_CTX *ctx,
  28                                   STACK_OF(CONF_VALUE) *nval);
  29 static int i2r_NAME_CONSTRAINTS(const X509V3_EXT_METHOD *method, void *a,
  30                                 BIO *bp, int ind);
  31 static int do_i2r_name_constraints(const X509V3_EXT_METHOD *method,
  32                                    STACK_OF(GENERAL_SUBTREE) *trees, BIO *bp,
  33                                    int ind, const char *name);
  34 static int print_nc_ipadd(BIO *bp, ASN1_OCTET_STRING *ip);
  35
  36 static int nc_match(GENERAL_NAME *gen, NAME_CONSTRAINTS *nc);
  37 static int nc_match_single(int effective_type, GENERAL_NAME *sub,
  38                            GENERAL_NAME *gen);
  39 static int nc_dn(const X509_NAME *sub, const X509_NAME *nm);
  40 static int nc_dns(ASN1_IA5STRING *sub, ASN1_IA5STRING *dns);
  41 static int nc_email(ASN1_IA5STRING *sub, ASN1_IA5STRING *eml);
  42 static int nc_email_eai(ASN1_TYPE *emltype, ASN1_IA5STRING *base);
  43 static int nc_uri(ASN1_IA5STRING *uri, ASN1_IA5STRING *base);
  44 static int nc_ip(ASN1_OCTET_STRING *ip, ASN1_OCTET_STRING *base);
  45
  46 const X509V3_EXT_METHOD ossl_v3_name_constraints = {
  47     NID_name_constraints, 0,
  48     ASN1_ITEM_ref(NAME_CONSTRAINTS),
  49     0, 0, 0, 0,
  50     0, 0,
  51     0, v2i_NAME_CONSTRAINTS,
  52     i2r_NAME_CONSTRAINTS, 0,
  53     NULL
  54 };
  55
  56 ASN1_SEQUENCE(GENERAL_SUBTREE) = {
  57         ASN1_SIMPLE(GENERAL_SUBTREE, base, GENERAL_NAME),
  58         ASN1_IMP_OPT(GENERAL_SUBTREE, minimum, ASN1_INTEGER, 0),
  59         ASN1_IMP_OPT(GENERAL_SUBTREE, maximum, ASN1_INTEGER, 1)
  60 } ASN1_SEQUENCE_END(GENERAL_SUBTREE)
  61
  62 ASN1_SEQUENCE(NAME_CONSTRAINTS) = {
  63         ASN1_IMP_SEQUENCE_OF_OPT(NAME_CONSTRAINTS, permittedSubtrees,
  64                                                         GENERAL_SUBTREE, 0),
  65         ASN1_IMP_SEQUENCE_OF_OPT(NAME_CONSTRAINTS, excludedSubtrees,
  66                                                         GENERAL_SUBTREE, 1),
  67 } ASN1_SEQUENCE_END(NAME_CONSTRAINTS)
  68
  69
  70 IMPLEMENT_ASN1_ALLOC_FUNCTIONS(GENERAL_SUBTREE)
  71 IMPLEMENT_ASN1_ALLOC_FUNCTIONS(NAME_CONSTRAINTS)
  72
  73
  74 #define IA5_OFFSET_LEN(ia5base, offset) \
  75     ((ia5base)->length - ((unsigned char *)(offset) - (ia5base)->data))
  76
  77 /* Like memchr but for ASN1_IA5STRING. Additionally you can specify the
  78  * starting point to search from
  79  */
  80 # define ia5memchr(str, start, c) memchr(start, c, IA5_OFFSET_LEN(str, start))
  81
  82 /* Like memrrchr but for ASN1_IA5STRING */
  83 static char *ia5memrchr(ASN1_IA5STRING *str, int c)
  84 {
  85     int i;
  86
  87     for (i = str->length; i > 0 && str->data[i - 1] != c; i--);
  88
  89     if (i == 0)
  90         return NULL;
  91
  92     return (char *)&str->data[i - 1];
  93 }
  94
  95 /*
  96  * We cannot use strncasecmp here because that applies locale specific rules. It
  97  * also doesn't work with ASN1_STRINGs that may have embedded NUL characters.
  98  * For example in Turkish 'I' is not the uppercase character for 'i'. We need to
  99  * do a simple ASCII case comparison ignoring the locale (that is why we use
 100  * numeric constants below).
 101  */
 102 static int ia5ncasecmp(const char *s1, const char *s2, size_t n)
 103 {
 104     for (; n > 0; n--, s1++, s2++) {
 105         if (*s1 != *s2) {
 106             unsigned char c1 = (unsigned char)*s1, c2 = (unsigned char)*s2;
 107
 108             /* Convert to lower case */
 109             if (c1 >= 0x41 /* A */ && c1 <= 0x5A /* Z */)
 110                 c1 += 0x20;
 111             if (c2 >= 0x41 /* A */ && c2 <= 0x5A /* Z */)
 112                 c2 += 0x20;
 113
 114             if (c1 == c2)
 115                 continue;
 116
 117             if (c1 < c2)
 118                 return -1;
 119
 120             /* c1 > c2 */
 121             return 1;
 122         }
 123     }
 124
 125     return 0;
 126 }
 127
 128 static void *v2i_NAME_CONSTRAINTS(const X509V3_EXT_METHOD *method,
 129                                   X509V3_CTX *ctx, STACK_OF(CONF_VALUE) *nval)
 130 {
 131     int i;
 132     CONF_VALUE tval, *val;
 133     STACK_OF(GENERAL_SUBTREE) **ptree = NULL;
 134     NAME_CONSTRAINTS *ncons = NULL;
 135     GENERAL_SUBTREE *sub = NULL;
 136
 137     ncons = NAME_CONSTRAINTS_new();
 138     if (ncons == NULL) {
 139         ERR_raise(ERR_LIB_X509V3, ERR_R_ASN1_LIB);
 140         goto err;
 141     }
 142     for (i = 0; i < sk_CONF_VALUE_num(nval); i++) {
 143         val = sk_CONF_VALUE_value(nval, i);
 144         if (HAS_PREFIX(val->name, "permitted") && val->name[9]) {
 145             ptree = &ncons->permittedSubtrees;
 146             tval.name = val->name + 10;
 147         } else if (HAS_PREFIX(val->name, "excluded") && val->name[8]) {
 148             ptree = &ncons->excludedSubtrees;
 149             tval.name = val->name + 9;
 150         } else {
 151             ERR_raise(ERR_LIB_X509V3, X509V3_R_INVALID_SYNTAX);
 152             goto err;
 153         }
 154         tval.value = val->value;
 155         sub = GENERAL_SUBTREE_new();
 156         if (sub == NULL) {
 157             ERR_raise(ERR_LIB_X509V3, ERR_R_ASN1_LIB);
 158             goto err;
 159         }
 160         if (!v2i_GENERAL_NAME_ex(sub->base, method, ctx, &tval, 1)) {
 161             ERR_raise(ERR_LIB_X509V3, ERR_R_X509V3_LIB);
 162             goto err;
 163         }
 164         if (*ptree == NULL)
 165             *ptree = sk_GENERAL_SUBTREE_new_null();
 166         if (*ptree == NULL || !sk_GENERAL_SUBTREE_push(*ptree, sub)) {
 167             ERR_raise(ERR_LIB_X509V3, ERR_R_CRYPTO_LIB);
 168             goto err;
 169         }
 170         sub = NULL;
 171     }
 172
 173     return ncons;
 174
 175  err:
 176     NAME_CONSTRAINTS_free(ncons);
 177     GENERAL_SUBTREE_free(sub);
 178
 179     return NULL;
 180 }
 181
 182 static int i2r_NAME_CONSTRAINTS(const X509V3_EXT_METHOD *method, void *a,
 183                                 BIO *bp, int ind)
 184 {
 185     NAME_CONSTRAINTS *ncons = a;
 186     do_i2r_name_constraints(method, ncons->permittedSubtrees,
 187                             bp, ind, "Permitted");
 188     if (ncons->permittedSubtrees && ncons->excludedSubtrees)
 189         BIO_puts(bp, "\n");
 190     do_i2r_name_constraints(method, ncons->excludedSubtrees,
 191                             bp, ind, "Excluded");
 192     return 1;
 193 }
 194
 195 static int do_i2r_name_constraints(const X509V3_EXT_METHOD *method,
 196                                    STACK_OF(GENERAL_SUBTREE) *trees,
 197                                    BIO *bp, int ind, const char *name)
 198 {
 199     GENERAL_SUBTREE *tree;
 200     int i;
 201     if (sk_GENERAL_SUBTREE_num(trees) > 0)
 202         BIO_printf(bp, "%*s%s:\n", ind, "", name);
 203     for (i = 0; i < sk_GENERAL_SUBTREE_num(trees); i++) {
 204         if (i > 0)
 205             BIO_puts(bp, "\n");
 206         tree = sk_GENERAL_SUBTREE_value(trees, i);
 207         BIO_printf(bp, "%*s", ind + 2, "");
 208         if (tree->base->type == GEN_IPADD)
 209             print_nc_ipadd(bp, tree->base->d.ip);
 210         else
 211             GENERAL_NAME_print(bp, tree->base);
 212     }
 213     return 1;
 214 }
 215
 216 static int print_nc_ipadd(BIO *bp, ASN1_OCTET_STRING *ip)
 217 {
 218     /* ip->length should be 8 or 32 and len1 == len2 == 4 or len1 == len2 == 16 */
 219     int len1 = ip->length >= 16 ? 16 : ip->length >= 4 ? 4 : ip->length;
 220     int len2 = ip->length - len1;
 221     char *ip1 = ossl_ipaddr_to_asc(ip->data, len1);
 222     char *ip2 = ossl_ipaddr_to_asc(ip->data + len1, len2);
 223     int ret = ip1 != NULL && ip2 != NULL
 224         && BIO_printf(bp, "IP:%s/%s", ip1, ip2) > 0;
 225
 226     OPENSSL_free(ip1);
 227     OPENSSL_free(ip2);
 228     return ret;
 229 }
 230
 231 #define NAME_CHECK_MAX (1 << 20)
 232
 233 static int add_lengths(int *out, int a, int b)
 234 {
 235     int err = 0;
 236
 237     /* sk_FOO_num(NULL) returns -1 but is effectively 0 when iterating. */
 238     if (a < 0)
 239         a = 0;
 240     if (b < 0)
 241         b = 0;
 242
 243     *out = safe_add_int(a, b, &err);
 244     return !err;
 245 }
 246
 247 /*-
 248  * Check a certificate conforms to a specified set of constraints.
 249  * Return values:
 250  *  X509_V_OK: All constraints obeyed.
 251  *  X509_V_ERR_PERMITTED_VIOLATION: Permitted subtree violation.
 252  *  X509_V_ERR_EXCLUDED_VIOLATION: Excluded subtree violation.
 253  *  X509_V_ERR_SUBTREE_MINMAX: Min or max values present and matching type.
 254  *  X509_V_ERR_UNSUPPORTED_CONSTRAINT_TYPE:  Unsupported constraint type.
 255  *  X509_V_ERR_UNSUPPORTED_CONSTRAINT_SYNTAX: bad unsupported constraint syntax.
 256  *  X509_V_ERR_UNSUPPORTED_NAME_SYNTAX: bad or unsupported syntax of name
 257  */
 258
 259 int NAME_CONSTRAINTS_check(X509 *x, NAME_CONSTRAINTS *nc)
 260 {
 261     int r, i, name_count, constraint_count;
 262     X509_NAME *nm;
 263
 264     nm = X509_get_subject_name(x);
 265
 266     /*
 267      * Guard against certificates with an excessive number of names or
 268      * constraints causing a computationally expensive name constraints check.
 269      */
 270     if (!add_lengths(&name_count, X509_NAME_entry_count(nm),
 271                      sk_GENERAL_NAME_num(x->altname))
 272         || !add_lengths(&constraint_count,
 273                         sk_GENERAL_SUBTREE_num(nc->permittedSubtrees),
 274                         sk_GENERAL_SUBTREE_num(nc->excludedSubtrees))
 275         || (name_count > 0 && constraint_count > NAME_CHECK_MAX / name_count))
 276         return X509_V_ERR_UNSPECIFIED;
 277
 278     if (X509_NAME_entry_count(nm) > 0) {
 279         GENERAL_NAME gntmp;
 280         gntmp.type = GEN_DIRNAME;
 281         gntmp.d.directoryName = nm;
 282
 283         r = nc_match(&gntmp, nc);
 284
 285         if (r != X509_V_OK)
 286             return r;
 287
 288         gntmp.type = GEN_EMAIL;
 289
 290         /* Process any email address attributes in subject name */
 291
 292         for (i = -1;;) {
 293             const X509_NAME_ENTRY *ne;
 294
 295             i = X509_NAME_get_index_by_NID(nm, NID_pkcs9_emailAddress, i);
 296             if (i == -1)
 297                 break;
 298             ne = X509_NAME_get_entry(nm, i);
 299             gntmp.d.rfc822Name = X509_NAME_ENTRY_get_data(ne);
 300             if (gntmp.d.rfc822Name->type != V_ASN1_IA5STRING)
 301                 return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX;
 302
 303             r = nc_match(&gntmp, nc);
 304
 305             if (r != X509_V_OK)
 306                 return r;
 307         }
 308
 309     }
 310
 311     for (i = 0; i < sk_GENERAL_NAME_num(x->altname); i++) {
 312         GENERAL_NAME *gen = sk_GENERAL_NAME_value(x->altname, i);
 313         r = nc_match(gen, nc);
 314         if (r != X509_V_OK)
 315             return r;
 316     }
 317
 318     return X509_V_OK;
 319
 320 }
 321
 322 static int cn2dnsid(ASN1_STRING *cn, unsigned char **dnsid, size_t *idlen)
 323 {
 324     int utf8_length;
 325     unsigned char *utf8_value;
 326     int i;
 327     int isdnsname = 0;
 328
 329     /* Don't leave outputs uninitialized */
 330     *dnsid = NULL;
 331     *idlen = 0;
 332
 333     /*-
 334      * Per RFC 6125, DNS-IDs representing internationalized domain names appear
 335      * in certificates in A-label encoded form:
 336      *
 337      *   https://tools.ietf.org/html/rfc6125#section-6.4.2
 338      *
 339      * The same applies to CNs which are intended to represent DNS names.
 340      * However, while in the SAN DNS-IDs are IA5Strings, as CNs they may be
 341      * needlessly encoded in 16-bit Unicode.  We perform a conversion to UTF-8
 342      * to ensure that we get an ASCII representation of any CNs that are
 343      * representable as ASCII, but just not encoded as ASCII.  The UTF-8 form
 344      * may contain some non-ASCII octets, and that's fine, such CNs are not
 345      * valid legacy DNS names.
 346      *
 347      * Note, 'int' is the return type of ASN1_STRING_to_UTF8() so that's what
 348      * we must use for 'utf8_length'.
 349      */
 350     if ((utf8_length = ASN1_STRING_to_UTF8(&utf8_value, cn)) < 0)
 351         return X509_V_ERR_OUT_OF_MEM;
 352
 353     /*
 354      * Some certificates have had names that include a *trailing* NUL byte.
 355      * Remove these harmless NUL characters. They would otherwise yield false
 356      * alarms with the following embedded NUL check.
 357      */
 358     while (utf8_length > 0 && utf8_value[utf8_length - 1] == '\0')
 359         --utf8_length;
 360
 361     /* Reject *embedded* NULs */
 362     if (memchr(utf8_value, 0, utf8_length) != NULL) {
 363         OPENSSL_free(utf8_value);
 364         return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX;
 365     }
 366
 367     /*
 368      * XXX: Deviation from strict DNS name syntax, also check names with '_'
 369      * Check DNS name syntax, any '-' or '.' must be internal,
 370      * and on either side of each '.' we can't have a '-' or '.'.
 371      *
 372      * If the name has just one label, we don't consider it a DNS name.  This
 373      * means that "CN=sometld" cannot be precluded by DNS name constraints, but
 374      * that is not a problem.
 375      */
 376     for (i = 0; i < utf8_length; ++i) {
 377         unsigned char c = utf8_value[i];
 378
 379         if ((c >= 'a' && c <= 'z')
 380             || (c >= 'A' && c <= 'Z')
 381             || (c >= '0' && c <= '9')
 382             || c == '_')
 383             continue;
 384
 385         /* Dot and hyphen cannot be first or last. */
 386         if (i > 0 && i < utf8_length - 1) {
 387             if (c == '-')
 388                 continue;
 389             /*
 390              * Next to a dot the preceding and following characters must not be
 391              * another dot or a hyphen.  Otherwise, record that the name is
 392              * plausible, since it has two or more labels.
 393              */
 394             if (c == '.'
 395                 && utf8_value[i + 1] != '.'
 396                 && utf8_value[i - 1] != '-'
 397                 && utf8_value[i + 1] != '-') {
 398                 isdnsname = 1;
 399                 continue;
 400             }
 401         }
 402         isdnsname = 0;
 403         break;
 404     }
 405
 406     if (isdnsname) {
 407         *dnsid = utf8_value;
 408         *idlen = (size_t)utf8_length;
 409         return X509_V_OK;
 410     }
 411     OPENSSL_free(utf8_value);
 412     return X509_V_OK;
 413 }
 414
 415 /*
 416  * Check CN against DNS-ID name constraints.
 417  */
 418 int NAME_CONSTRAINTS_check_CN(X509 *x, NAME_CONSTRAINTS *nc)
 419 {
 420     int r, i;
 421     const X509_NAME *nm = X509_get_subject_name(x);
 422     ASN1_STRING stmp;
 423     GENERAL_NAME gntmp;
 424
 425     stmp.flags = 0;
 426     stmp.type = V_ASN1_IA5STRING;
 427     gntmp.type = GEN_DNS;
 428     gntmp.d.dNSName = &stmp;
 429
 430     /* Process any commonName attributes in subject name */
 431
 432     for (i = -1;;) {
 433         X509_NAME_ENTRY *ne;
 434         ASN1_STRING *cn;
 435         unsigned char *idval;
 436         size_t idlen;
 437
 438         i = X509_NAME_get_index_by_NID(nm, NID_commonName, i);
 439         if (i == -1)
 440             break;
 441         ne = X509_NAME_get_entry(nm, i);
 442         cn = X509_NAME_ENTRY_get_data(ne);
 443
 444         /* Only process attributes that look like hostnames */
 445         if ((r = cn2dnsid(cn, &idval, &idlen)) != X509_V_OK)
 446             return r;
 447         if (idlen == 0)
 448             continue;
 449
 450         stmp.length = idlen;
 451         stmp.data = idval;
 452         r = nc_match(&gntmp, nc);
 453         OPENSSL_free(idval);
 454         if (r != X509_V_OK)
 455             return r;
 456     }
 457     return X509_V_OK;
 458 }
 459
 460 /*
 461  * Return nonzero if the GeneralSubtree has valid 'minimum' field
 462  * (must be absent or 0) and valid 'maximum' field (must be absent).
 463  */
 464 static int nc_minmax_valid(GENERAL_SUBTREE *sub) {
 465     BIGNUM *bn = NULL;
 466     int ok = 1;
 467
 468     if (sub->maximum)
 469         ok = 0;
 470
 471     if (sub->minimum) {
 472         bn = ASN1_INTEGER_to_BN(sub->minimum, NULL);
 473         if (bn == NULL || !BN_is_zero(bn))
 474             ok = 0;
 475         BN_free(bn);
 476     }
 477
 478     return ok;
 479 }
 480
 481 static int nc_match(GENERAL_NAME *gen, NAME_CONSTRAINTS *nc)
 482 {
 483     GENERAL_SUBTREE *sub;
 484     int i, r, match = 0;
 485     int effective_type = gen->type;
 486
 487     /*
 488      * We need to compare not gen->type field but an "effective" type because
 489      * the otherName field may contain EAI email address treated specially
 490      * according to RFC 8398, section 6
 491      */
 492     if (effective_type == GEN_OTHERNAME &&
 493         (OBJ_obj2nid(gen->d.otherName->type_id) == NID_id_on_SmtpUTF8Mailbox)) {
 494         effective_type = GEN_EMAIL;
 495     }
 496
 497     /*
 498      * Permitted subtrees: if any subtrees exist of matching the type at
 499      * least one subtree must match.
 500      */
 501
 502     for (i = 0; i < sk_GENERAL_SUBTREE_num(nc->permittedSubtrees); i++) {
 503         sub = sk_GENERAL_SUBTREE_value(nc->permittedSubtrees, i);
 504         if (effective_type != sub->base->type
 505             || (effective_type == GEN_OTHERNAME &&
 506                 OBJ_cmp(gen->d.otherName->type_id,
 507                         sub->base->d.otherName->type_id) != 0))
 508             continue;
 509         if (!nc_minmax_valid(sub))
 510             return X509_V_ERR_SUBTREE_MINMAX;
 511         /* If we already have a match don't bother trying any more */
 512         if (match == 2)
 513             continue;
 514         if (match == 0)
 515             match = 1;
 516         r = nc_match_single(effective_type, gen, sub->base);
 517         if (r == X509_V_OK)
 518             match = 2;
 519         else if (r != X509_V_ERR_PERMITTED_VIOLATION)
 520             return r;
 521     }
 522
 523     if (match == 1)
 524         return X509_V_ERR_PERMITTED_VIOLATION;
 525
 526     /* Excluded subtrees: must not match any of these */
 527
 528     for (i = 0; i < sk_GENERAL_SUBTREE_num(nc->excludedSubtrees); i++) {
 529         sub = sk_GENERAL_SUBTREE_value(nc->excludedSubtrees, i);
 530         if (effective_type != sub->base->type
 531             || (effective_type == GEN_OTHERNAME &&
 532                 OBJ_cmp(gen->d.otherName->type_id,
 533                         sub->base->d.otherName->type_id) != 0))
 534             continue;
 535         if (!nc_minmax_valid(sub))
 536             return X509_V_ERR_SUBTREE_MINMAX;
 537
 538         r = nc_match_single(effective_type, gen, sub->base);
 539         if (r == X509_V_OK)
 540             return X509_V_ERR_EXCLUDED_VIOLATION;
 541         else if (r != X509_V_ERR_PERMITTED_VIOLATION)
 542             return r;
 543
 544     }
 545
 546     return X509_V_OK;
 547
 548 }
 549
 550 static int nc_match_single(int effective_type, GENERAL_NAME *gen,
 551                            GENERAL_NAME *base)
 552 {
 553     switch (gen->type) {
 554     case GEN_OTHERNAME:
 555         switch (effective_type) {
 556         case GEN_EMAIL:
 557             /*
 558              * We are here only when we have SmtpUTF8 name,
 559              * so we match the value of othername with base->d.rfc822Name
 560              */
 561             return nc_email_eai(gen->d.otherName->value, base->d.rfc822Name);
 562
 563         default:
 564             return X509_V_ERR_UNSUPPORTED_CONSTRAINT_TYPE;
 565         }
 566
 567     case GEN_DIRNAME:
 568         return nc_dn(gen->d.directoryName, base->d.directoryName);
 569
 570     case GEN_DNS:
 571         return nc_dns(gen->d.dNSName, base->d.dNSName);
 572
 573     case GEN_EMAIL:
 574         return nc_email(gen->d.rfc822Name, base->d.rfc822Name);
 575
 576     case GEN_URI:
 577         return nc_uri(gen->d.uniformResourceIdentifier,
 578                       base->d.uniformResourceIdentifier);
 579
 580     case GEN_IPADD:
 581         return nc_ip(gen->d.iPAddress, base->d.iPAddress);
 582
 583     default:
 584         return X509_V_ERR_UNSUPPORTED_CONSTRAINT_TYPE;
 585     }
 586
 587 }
 588
 589 /*
 590  * directoryName name constraint matching. The canonical encoding of
 591  * X509_NAME makes this comparison easy. It is matched if the subtree is a
 592  * subset of the name.
 593  */
 594
 595 static int nc_dn(const X509_NAME *nm, const X509_NAME *base)
 596 {
 597     /* Ensure canonical encodings are up to date.  */
 598     if (nm->modified && i2d_X509_NAME(nm, NULL) < 0)
 599         return X509_V_ERR_OUT_OF_MEM;
 600     if (base->modified && i2d_X509_NAME(base, NULL) < 0)
 601         return X509_V_ERR_OUT_OF_MEM;
 602     if (base->canon_enclen > nm->canon_enclen)
 603         return X509_V_ERR_PERMITTED_VIOLATION;
 604     if (memcmp(base->canon_enc, nm->canon_enc, base->canon_enclen))
 605         return X509_V_ERR_PERMITTED_VIOLATION;
 606     return X509_V_OK;
 607 }
 608
 609 static int nc_dns(ASN1_IA5STRING *dns, ASN1_IA5STRING *base)
 610 {
 611     char *baseptr = (char *)base->data;
 612     char *dnsptr = (char *)dns->data;
 613
 614     /* Empty matches everything */
 615     if (base->length == 0)
 616         return X509_V_OK;
 617
 618     if (dns->length < base->length)
 619         return X509_V_ERR_PERMITTED_VIOLATION;
 620
 621     /*
 622      * Otherwise can add zero or more components on the left so compare RHS
 623      * and if dns is longer and expect '.' as preceding character.
 624      */
 625     if (dns->length > base->length) {
 626         dnsptr += dns->length - base->length;
 627         if (*baseptr != '.' && dnsptr[-1] != '.')
 628             return X509_V_ERR_PERMITTED_VIOLATION;
 629     }
 630
 631     if (ia5ncasecmp(baseptr, dnsptr, base->length))
 632         return X509_V_ERR_PERMITTED_VIOLATION;
 633
 634     return X509_V_OK;
 635
 636 }
 637
 638 /*
 639  * This function implements comparison between ASCII/U-label in emltype
 640  * and A-label in base according to RFC 8398, section 6.
 641  * Convert base to U-label and ASCII-parts of domain names, for base
 642  * Octet-to-octet comparison of `emltype` and `base` hostname parts
 643  * (ASCII-parts should be compared in case-insensitive manner)
 644  */
 645 static int nc_email_eai(ASN1_TYPE *emltype, ASN1_IA5STRING *base)
 646 {
 647     ASN1_UTF8STRING *eml;
 648     char *baseptr = NULL;
 649     const char *emlptr;
 650     const char *emlat;
 651     char ulabel[256];
 652     size_t size = sizeof(ulabel);
 653     int ret = X509_V_OK;
 654     size_t emlhostlen;
 655
 656     /* We do not accept embedded NUL characters */
 657     if (base->length > 0 && memchr(base->data, 0, base->length) != NULL)
 658         return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX;
 659
 660     /* 'base' may not be NUL terminated. Create a copy that is */
 661     baseptr = OPENSSL_strndup((char *)base->data, base->length);
 662     if (baseptr == NULL)
 663         return X509_V_ERR_OUT_OF_MEM;
 664
 665     if (emltype->type != V_ASN1_UTF8STRING) {
 666         ret = X509_V_ERR_UNSUPPORTED_NAME_SYNTAX;
 667         goto end;
 668     }
 669
 670     eml = emltype->value.utf8string;
 671     emlptr = (char *)eml->data;
 672     emlat = ia5memrchr(eml, '@');
 673
 674     if (emlat == NULL) {
 675         ret = X509_V_ERR_UNSUPPORTED_NAME_SYNTAX;
 676         goto end;
 677     }
 678
 679     /* Special case: initial '.' is RHS match */
 680     if (*baseptr == '.') {
 681         ulabel[0] = '.';
 682         if (ossl_a2ulabel(baseptr, ulabel + 1, size - 1) <= 0) {
 683             ret = X509_V_ERR_UNSPECIFIED;
 684             goto end;
 685         }
 686
 687         if ((size_t)eml->length > strlen(ulabel)) {
 688             emlptr += eml->length - strlen(ulabel);
 689             /* X509_V_OK */
 690             if (ia5ncasecmp(ulabel, emlptr, strlen(ulabel)) == 0)
 691                 goto end;
 692         }
 693         ret = X509_V_ERR_PERMITTED_VIOLATION;
 694         goto end;
 695     }
 696
 697     if (ossl_a2ulabel(baseptr, ulabel, size) <= 0) {
 698         ret = X509_V_ERR_UNSPECIFIED;
 699         goto end;
 700     }
 701     /* Just have hostname left to match: case insensitive */
 702     emlptr = emlat + 1;
 703     emlhostlen = IA5_OFFSET_LEN(eml, emlptr);
 704     if (emlhostlen != strlen(ulabel)
 705             || ia5ncasecmp(ulabel, emlptr, emlhostlen) != 0) {
 706         ret = X509_V_ERR_PERMITTED_VIOLATION;
 707         goto end;
 708     }
 709
 710  end:
 711     OPENSSL_free(baseptr);
 712     return ret;
 713 }
 714
 715 static int nc_email(ASN1_IA5STRING *eml, ASN1_IA5STRING *base)
 716 {
 717     const char *baseptr = (char *)base->data;
 718     const char *emlptr = (char *)eml->data;
 719     const char *baseat = ia5memrchr(base, '@');
 720     const char *emlat = ia5memrchr(eml, '@');
 721     size_t basehostlen, emlhostlen;
 722
 723     if (!emlat)
 724         return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX;
 725     /* Special case: initial '.' is RHS match */
 726     if (!baseat && base->length > 0 && (*baseptr == '.')) {
 727         if (eml->length > base->length) {
 728             emlptr += eml->length - base->length;
 729             if (ia5ncasecmp(baseptr, emlptr, base->length) == 0)
 730                 return X509_V_OK;
 731         }
 732         return X509_V_ERR_PERMITTED_VIOLATION;
 733     }
 734
 735     /* If we have anything before '@' match local part */
 736
 737     if (baseat) {
 738         if (baseat != baseptr) {
 739             if ((baseat - baseptr) != (emlat - emlptr))
 740                 return X509_V_ERR_PERMITTED_VIOLATION;
 741             if (memchr(baseptr, 0, baseat - baseptr) ||
 742                 memchr(emlptr, 0, emlat - emlptr))
 743                 return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX;
 744             /* Case sensitive match of local part */
 745             if (strncmp(baseptr, emlptr, emlat - emlptr))
 746                 return X509_V_ERR_PERMITTED_VIOLATION;
 747         }
 748         /* Position base after '@' */
 749         baseptr = baseat + 1;
 750     }
 751     emlptr = emlat + 1;
 752     basehostlen = IA5_OFFSET_LEN(base, baseptr);
 753     emlhostlen = IA5_OFFSET_LEN(eml, emlptr);
 754     /* Just have hostname left to match: case insensitive */
 755     if (basehostlen != emlhostlen || ia5ncasecmp(baseptr, emlptr, emlhostlen))
 756         return X509_V_ERR_PERMITTED_VIOLATION;
 757
 758     return X509_V_OK;
 759
 760 }
 761
 762 static int nc_uri(ASN1_IA5STRING *uri, ASN1_IA5STRING *base)
 763 {
 764     const char *baseptr = (char *)base->data;
 765     const char *hostptr = (char *)uri->data;
 766     const char *p = ia5memchr(uri, (char *)uri->data, ':');
 767     int hostlen;
 768
 769     /* Check for foo:// and skip past it */
 770     if (p == NULL
 771             || IA5_OFFSET_LEN(uri, p) < 3
 772             || p[1] != '/'
 773             || p[2] != '/')
 774         return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX;
 775     hostptr = p + 3;
 776
 777     /* Determine length of hostname part of URI */
 778
 779     /* Look for a port indicator as end of hostname first */
 780
 781     p = ia5memchr(uri, hostptr, ':');
 782     /* Otherwise look for trailing slash */
 783     if (p == NULL)
 784         p = ia5memchr(uri, hostptr, '/');
 785
 786     if (p == NULL)
 787         hostlen = IA5_OFFSET_LEN(uri, hostptr);
 788     else
 789         hostlen = p - hostptr;
 790
 791     if (hostlen == 0)
 792         return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX;
 793
 794     /* Special case: initial '.' is RHS match */
 795     if (base->length > 0 && *baseptr == '.') {
 796         if (hostlen > base->length) {
 797             p = hostptr + hostlen - base->length;
 798             if (ia5ncasecmp(p, baseptr, base->length) == 0)
 799                 return X509_V_OK;
 800         }
 801         return X509_V_ERR_PERMITTED_VIOLATION;
 802     }
 803
 804     if ((base->length != (int)hostlen)
 805         || ia5ncasecmp(hostptr, baseptr, hostlen))
 806         return X509_V_ERR_PERMITTED_VIOLATION;
 807
 808     return X509_V_OK;
 809
 810 }
 811
 812 static int nc_ip(ASN1_OCTET_STRING *ip, ASN1_OCTET_STRING *base)
 813 {
 814     int hostlen, baselen, i;
 815     unsigned char *hostptr, *baseptr, *maskptr;
 816     hostptr = ip->data;
 817     hostlen = ip->length;
 818     baseptr = base->data;
 819     baselen = base->length;
 820
 821     /* Invalid if not IPv4 or IPv6 */
 822     if (!((hostlen == 4) || (hostlen == 16)))
 823         return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX;
 824     if (!((baselen == 8) || (baselen == 32)))
 825         return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX;
 826
 827     /* Do not match IPv4 with IPv6 */
 828     if (hostlen * 2 != baselen)
 829         return X509_V_ERR_PERMITTED_VIOLATION;
 830
 831     maskptr = base->data + hostlen;
 832
 833     /* Considering possible not aligned base ipAddress */
 834     /* Not checking for wrong mask definition: i.e.: 255.0.255.0 */
 835     for (i = 0; i < hostlen; i++)
 836         if ((hostptr[i] & maskptr[i]) != (baseptr[i] & maskptr[i]))
 837             return X509_V_ERR_PERMITTED_VIOLATION;
 838
 839     return X509_V_OK;
 840
 841 }