/* * Copyright 2003-2020 The OpenSSL Project Authors. All Rights Reserved. * * Licensed under the Apache License 2.0 (the "License"). You may not use * this file except in compliance with the License. You can obtain a copy * in the file LICENSE in the source distribution or at * https://www.openssl.org/source/license.html */ #include "internal/cryptlib.h" #include "internal/numbers.h" #include #include "crypto/asn1.h" #include #include #include #include #include "crypto/x509.h" #include "ext_dat.h" DEFINE_STACK_OF(CONF_VALUE) DEFINE_STACK_OF(GENERAL_NAME) DEFINE_STACK_OF(GENERAL_SUBTREE) static void *v2i_NAME_CONSTRAINTS(const X509V3_EXT_METHOD *method, X509V3_CTX *ctx, STACK_OF(CONF_VALUE) *nval); static int i2r_NAME_CONSTRAINTS(const X509V3_EXT_METHOD *method, void *a, BIO *bp, int ind); static int do_i2r_name_constraints(const X509V3_EXT_METHOD *method, STACK_OF(GENERAL_SUBTREE) *trees, BIO *bp, int ind, const char *name); static int print_nc_ipadd(BIO *bp, ASN1_OCTET_STRING *ip); static int nc_match(GENERAL_NAME *gen, NAME_CONSTRAINTS *nc); static int nc_match_single(GENERAL_NAME *sub, GENERAL_NAME *gen); static int nc_dn(const X509_NAME *sub, const X509_NAME *nm); static int nc_dns(ASN1_IA5STRING *sub, ASN1_IA5STRING *dns); static int nc_email(ASN1_IA5STRING *sub, ASN1_IA5STRING *eml); static int nc_uri(ASN1_IA5STRING *uri, ASN1_IA5STRING *base); static int nc_ip(ASN1_OCTET_STRING *ip, ASN1_OCTET_STRING *base); const X509V3_EXT_METHOD v3_name_constraints = { NID_name_constraints, 0, ASN1_ITEM_ref(NAME_CONSTRAINTS), 0, 0, 0, 0, 0, 0, 0, v2i_NAME_CONSTRAINTS, i2r_NAME_CONSTRAINTS, 0, NULL }; ASN1_SEQUENCE(GENERAL_SUBTREE) = { ASN1_SIMPLE(GENERAL_SUBTREE, base, GENERAL_NAME), ASN1_IMP_OPT(GENERAL_SUBTREE, minimum, ASN1_INTEGER, 0), ASN1_IMP_OPT(GENERAL_SUBTREE, maximum, ASN1_INTEGER, 1) } ASN1_SEQUENCE_END(GENERAL_SUBTREE) ASN1_SEQUENCE(NAME_CONSTRAINTS) = { ASN1_IMP_SEQUENCE_OF_OPT(NAME_CONSTRAINTS, permittedSubtrees, GENERAL_SUBTREE, 0), ASN1_IMP_SEQUENCE_OF_OPT(NAME_CONSTRAINTS, excludedSubtrees, GENERAL_SUBTREE, 1), } ASN1_SEQUENCE_END(NAME_CONSTRAINTS) IMPLEMENT_ASN1_ALLOC_FUNCTIONS(GENERAL_SUBTREE) IMPLEMENT_ASN1_ALLOC_FUNCTIONS(NAME_CONSTRAINTS) /* * We cannot use strncasecmp here because that applies locale specific rules. * For example in Turkish 'I' is not the uppercase character for 'i'. We need to * do a simple ASCII case comparison ignoring the locale (that is why we use * numeric constants below). */ static int ia5ncasecmp(const char *s1, const char *s2, size_t n) { for (; n > 0; n--, s1++, s2++) { if (*s1 != *s2) { unsigned char c1 = (unsigned char)*s1, c2 = (unsigned char)*s2; /* Convert to lower case */ if (c1 >= 0x41 /* A */ && c1 <= 0x5A /* Z */) c1 += 0x20; if (c2 >= 0x41 /* A */ && c2 <= 0x5A /* Z */) c2 += 0x20; if (c1 == c2) continue; if (c1 < c2) return -1; /* c1 > c2 */ return 1; } else if (*s1 == 0) { /* If we get here we know that *s2 == 0 too */ return 0; } } return 0; } static int ia5casecmp(const char *s1, const char *s2) { return ia5ncasecmp(s1, s2, SIZE_MAX); } static void *v2i_NAME_CONSTRAINTS(const X509V3_EXT_METHOD *method, X509V3_CTX *ctx, STACK_OF(CONF_VALUE) *nval) { int i; CONF_VALUE tval, *val; STACK_OF(GENERAL_SUBTREE) **ptree = NULL; NAME_CONSTRAINTS *ncons = NULL; GENERAL_SUBTREE *sub = NULL; ncons = NAME_CONSTRAINTS_new(); if (ncons == NULL) goto memerr; for (i = 0; i < sk_CONF_VALUE_num(nval); i++) { val = sk_CONF_VALUE_value(nval, i); if (strncmp(val->name, "permitted", 9) == 0 && val->name[9]) { ptree = &ncons->permittedSubtrees; tval.name = val->name + 10; } else if (strncmp(val->name, "excluded", 8) == 0 && val->name[8]) { ptree = &ncons->excludedSubtrees; tval.name = val->name + 9; } else { X509V3err(X509V3_F_V2I_NAME_CONSTRAINTS, X509V3_R_INVALID_SYNTAX); goto err; } tval.value = val->value; sub = GENERAL_SUBTREE_new(); if (sub == NULL) goto memerr; if (!v2i_GENERAL_NAME_ex(sub->base, method, ctx, &tval, 1)) goto err; if (*ptree == NULL) *ptree = sk_GENERAL_SUBTREE_new_null(); if (*ptree == NULL || !sk_GENERAL_SUBTREE_push(*ptree, sub)) goto memerr; sub = NULL; } return ncons; memerr: X509V3err(X509V3_F_V2I_NAME_CONSTRAINTS, ERR_R_MALLOC_FAILURE); err: NAME_CONSTRAINTS_free(ncons); GENERAL_SUBTREE_free(sub); return NULL; } static int i2r_NAME_CONSTRAINTS(const X509V3_EXT_METHOD *method, void *a, BIO *bp, int ind) { NAME_CONSTRAINTS *ncons = a; do_i2r_name_constraints(method, ncons->permittedSubtrees, bp, ind, "Permitted"); if (ncons->permittedSubtrees && ncons->excludedSubtrees) BIO_puts(bp, "\n"); do_i2r_name_constraints(method, ncons->excludedSubtrees, bp, ind, "Excluded"); return 1; } static int do_i2r_name_constraints(const X509V3_EXT_METHOD *method, STACK_OF(GENERAL_SUBTREE) *trees, BIO *bp, int ind, const char *name) { GENERAL_SUBTREE *tree; int i; if (sk_GENERAL_SUBTREE_num(trees) > 0) BIO_printf(bp, "%*s%s:\n", ind, "", name); for (i = 0; i < sk_GENERAL_SUBTREE_num(trees); i++) { if (i > 0) BIO_puts(bp, "\n"); tree = sk_GENERAL_SUBTREE_value(trees, i); BIO_printf(bp, "%*s", ind + 2, ""); if (tree->base->type == GEN_IPADD) print_nc_ipadd(bp, tree->base->d.ip); else GENERAL_NAME_print(bp, tree->base); } return 1; } static int print_nc_ipadd(BIO *bp, ASN1_OCTET_STRING *ip) { /* ip->length should be 8 or 32 and len1 == len2 == 4 or len1 == len2 == 16 */ int len1 = ip->length >= 16 ? 16 : ip->length >= 4 ? 4 : ip->length; int len2 = ip->length - len1; char *ip1 = ipaddr_to_asc(ip->data, len1); char *ip2 = ipaddr_to_asc(ip->data + len1, len2); int ret = ret = ip1 != NULL && ip2 != NULL && BIO_printf(bp, "IP:%s/%s", ip1, ip2) > 0; OPENSSL_free(ip1); OPENSSL_free(ip2); return ret; } #define NAME_CHECK_MAX (1 << 20) static int add_lengths(int *out, int a, int b) { /* sk_FOO_num(NULL) returns -1 but is effectively 0 when iterating. */ if (a < 0) a = 0; if (b < 0) b = 0; if (a > INT_MAX - b) return 0; *out = a + b; return 1; } /*- * Check a certificate conforms to a specified set of constraints. * Return values: * X509_V_OK: All constraints obeyed. * X509_V_ERR_PERMITTED_VIOLATION: Permitted subtree violation. * X509_V_ERR_EXCLUDED_VIOLATION: Excluded subtree violation. * X509_V_ERR_SUBTREE_MINMAX: Min or max values present and matching type. * X509_V_ERR_UNSUPPORTED_CONSTRAINT_TYPE: Unsupported constraint type. * X509_V_ERR_UNSUPPORTED_CONSTRAINT_SYNTAX: bad unsupported constraint syntax. * X509_V_ERR_UNSUPPORTED_NAME_SYNTAX: bad or unsupported syntax of name */ int NAME_CONSTRAINTS_check(X509 *x, NAME_CONSTRAINTS *nc) { int r, i, name_count, constraint_count; X509_NAME *nm; nm = X509_get_subject_name(x); /* * Guard against certificates with an excessive number of names or * constraints causing a computationally expensive name constraints check. */ if (!add_lengths(&name_count, X509_NAME_entry_count(nm), sk_GENERAL_NAME_num(x->altname)) || !add_lengths(&constraint_count, sk_GENERAL_SUBTREE_num(nc->permittedSubtrees), sk_GENERAL_SUBTREE_num(nc->excludedSubtrees)) || (name_count > 0 && constraint_count > NAME_CHECK_MAX / name_count)) return X509_V_ERR_UNSPECIFIED; if (X509_NAME_entry_count(nm) > 0) { GENERAL_NAME gntmp; gntmp.type = GEN_DIRNAME; gntmp.d.directoryName = nm; r = nc_match(&gntmp, nc); if (r != X509_V_OK) return r; gntmp.type = GEN_EMAIL; /* Process any email address attributes in subject name */ for (i = -1;;) { const X509_NAME_ENTRY *ne; i = X509_NAME_get_index_by_NID(nm, NID_pkcs9_emailAddress, i); if (i == -1) break; ne = X509_NAME_get_entry(nm, i); gntmp.d.rfc822Name = X509_NAME_ENTRY_get_data(ne); if (gntmp.d.rfc822Name->type != V_ASN1_IA5STRING) return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX; r = nc_match(&gntmp, nc); if (r != X509_V_OK) return r; } } for (i = 0; i < sk_GENERAL_NAME_num(x->altname); i++) { GENERAL_NAME *gen = sk_GENERAL_NAME_value(x->altname, i); r = nc_match(gen, nc); if (r != X509_V_OK) return r; } return X509_V_OK; } static int cn2dnsid(ASN1_STRING *cn, unsigned char **dnsid, size_t *idlen) { int utf8_length; unsigned char *utf8_value; int i; int isdnsname = 0; /* Don't leave outputs uninitialized */ *dnsid = NULL; *idlen = 0; /*- * Per RFC 6125, DNS-IDs representing internationalized domain names appear * in certificates in A-label encoded form: * * https://tools.ietf.org/html/rfc6125#section-6.4.2 * * The same applies to CNs which are intended to represent DNS names. * However, while in the SAN DNS-IDs are IA5Strings, as CNs they may be * needlessly encoded in 16-bit Unicode. We perform a conversion to UTF-8 * to ensure that we get an ASCII representation of any CNs that are * representable as ASCII, but just not encoded as ASCII. The UTF-8 form * may contain some non-ASCII octets, and that's fine, such CNs are not * valid legacy DNS names. * * Note, 'int' is the return type of ASN1_STRING_to_UTF8() so that's what * we must use for 'utf8_length'. */ if ((utf8_length = ASN1_STRING_to_UTF8(&utf8_value, cn)) < 0) return X509_V_ERR_OUT_OF_MEM; /* * Some certificates have had names that include a *trailing* NUL byte. * Remove these harmless NUL characters. They would otherwise yield false * alarms with the following embedded NUL check. */ while (utf8_length > 0 && utf8_value[utf8_length - 1] == '\0') --utf8_length; /* Reject *embedded* NULs */ if ((size_t)utf8_length != strlen((char *)utf8_value)) { OPENSSL_free(utf8_value); return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX; } /* * XXX: Deviation from strict DNS name syntax, also check names with '_' * Check DNS name syntax, any '-' or '.' must be internal, * and on either side of each '.' we can't have a '-' or '.'. * * If the name has just one label, we don't consider it a DNS name. This * means that "CN=sometld" cannot be precluded by DNS name constraints, but * that is not a problem. */ for (i = 0; i < utf8_length; ++i) { unsigned char c = utf8_value[i]; if ((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') || (c >= '0' && c <= '9') || c == '_') continue; /* Dot and hyphen cannot be first or last. */ if (i > 0 && i < utf8_length - 1) { if (c == '-') continue; /* * Next to a dot the preceding and following characters must not be * another dot or a hyphen. Otherwise, record that the name is * plausible, since it has two or more labels. */ if (c == '.' && utf8_value[i + 1] != '.' && utf8_value[i - 1] != '-' && utf8_value[i + 1] != '-') { isdnsname = 1; continue; } } isdnsname = 0; break; } if (isdnsname) { *dnsid = utf8_value; *idlen = (size_t)utf8_length; return X509_V_OK; } OPENSSL_free(utf8_value); return X509_V_OK; } /* * Check CN against DNS-ID name constraints. */ int NAME_CONSTRAINTS_check_CN(X509 *x, NAME_CONSTRAINTS *nc) { int r, i; const X509_NAME *nm = X509_get_subject_name(x); ASN1_STRING stmp; GENERAL_NAME gntmp; stmp.flags = 0; stmp.type = V_ASN1_IA5STRING; gntmp.type = GEN_DNS; gntmp.d.dNSName = &stmp; /* Process any commonName attributes in subject name */ for (i = -1;;) { X509_NAME_ENTRY *ne; ASN1_STRING *cn; unsigned char *idval; size_t idlen; i = X509_NAME_get_index_by_NID(nm, NID_commonName, i); if (i == -1) break; ne = X509_NAME_get_entry(nm, i); cn = X509_NAME_ENTRY_get_data(ne); /* Only process attributes that look like host names */ if ((r = cn2dnsid(cn, &idval, &idlen)) != X509_V_OK) return r; if (idlen == 0) continue; stmp.length = idlen; stmp.data = idval; r = nc_match(&gntmp, nc); OPENSSL_free(idval); if (r != X509_V_OK) return r; } return X509_V_OK; } /* * Return nonzero if the GeneralSubtree has valid 'minimum' field * (must be absent or 0) and valid 'maximum' field (must be absent). */ static int nc_minmax_valid(GENERAL_SUBTREE *sub) { BIGNUM *bn = NULL; int ok = 1; if (sub->maximum) ok = 0; if (sub->minimum) { bn = ASN1_INTEGER_to_BN(sub->minimum, NULL); if (bn == NULL || !BN_is_zero(bn)) ok = 0; BN_free(bn); } return ok; } static int nc_match(GENERAL_NAME *gen, NAME_CONSTRAINTS *nc) { GENERAL_SUBTREE *sub; int i, r, match = 0; /* * Permitted subtrees: if any subtrees exist of matching the type at * least one subtree must match. */ for (i = 0; i < sk_GENERAL_SUBTREE_num(nc->permittedSubtrees); i++) { sub = sk_GENERAL_SUBTREE_value(nc->permittedSubtrees, i); if (gen->type != sub->base->type) continue; if (!nc_minmax_valid(sub)) return X509_V_ERR_SUBTREE_MINMAX; /* If we already have a match don't bother trying any more */ if (match == 2) continue; if (match == 0) match = 1; r = nc_match_single(gen, sub->base); if (r == X509_V_OK) match = 2; else if (r != X509_V_ERR_PERMITTED_VIOLATION) return r; } if (match == 1) return X509_V_ERR_PERMITTED_VIOLATION; /* Excluded subtrees: must not match any of these */ for (i = 0; i < sk_GENERAL_SUBTREE_num(nc->excludedSubtrees); i++) { sub = sk_GENERAL_SUBTREE_value(nc->excludedSubtrees, i); if (gen->type != sub->base->type) continue; if (!nc_minmax_valid(sub)) return X509_V_ERR_SUBTREE_MINMAX; r = nc_match_single(gen, sub->base); if (r == X509_V_OK) return X509_V_ERR_EXCLUDED_VIOLATION; else if (r != X509_V_ERR_PERMITTED_VIOLATION) return r; } return X509_V_OK; } static int nc_match_single(GENERAL_NAME *gen, GENERAL_NAME *base) { switch (base->type) { case GEN_DIRNAME: return nc_dn(gen->d.directoryName, base->d.directoryName); case GEN_DNS: return nc_dns(gen->d.dNSName, base->d.dNSName); case GEN_EMAIL: return nc_email(gen->d.rfc822Name, base->d.rfc822Name); case GEN_URI: return nc_uri(gen->d.uniformResourceIdentifier, base->d.uniformResourceIdentifier); case GEN_IPADD: return nc_ip(gen->d.iPAddress, base->d.iPAddress); default: return X509_V_ERR_UNSUPPORTED_CONSTRAINT_TYPE; } } /* * directoryName name constraint matching. The canonical encoding of * X509_NAME makes this comparison easy. It is matched if the subtree is a * subset of the name. */ static int nc_dn(const X509_NAME *nm, const X509_NAME *base) { /* Ensure canonical encodings are up to date. */ if (nm->modified && i2d_X509_NAME(nm, NULL) < 0) return X509_V_ERR_OUT_OF_MEM; if (base->modified && i2d_X509_NAME(base, NULL) < 0) return X509_V_ERR_OUT_OF_MEM; if (base->canon_enclen > nm->canon_enclen) return X509_V_ERR_PERMITTED_VIOLATION; if (memcmp(base->canon_enc, nm->canon_enc, base->canon_enclen)) return X509_V_ERR_PERMITTED_VIOLATION; return X509_V_OK; } static int nc_dns(ASN1_IA5STRING *dns, ASN1_IA5STRING *base) { char *baseptr = (char *)base->data; char *dnsptr = (char *)dns->data; /* Empty matches everything */ if (*baseptr == '\0') return X509_V_OK; /* * Otherwise can add zero or more components on the left so compare RHS * and if dns is longer and expect '.' as preceding character. */ if (dns->length > base->length) { dnsptr += dns->length - base->length; if (*baseptr != '.' && dnsptr[-1] != '.') return X509_V_ERR_PERMITTED_VIOLATION; } if (ia5casecmp(baseptr, dnsptr)) return X509_V_ERR_PERMITTED_VIOLATION; return X509_V_OK; } static int nc_email(ASN1_IA5STRING *eml, ASN1_IA5STRING *base) { const char *baseptr = (char *)base->data; const char *emlptr = (char *)eml->data; const char *baseat = strchr(baseptr, '@'); const char *emlat = strchr(emlptr, '@'); if (!emlat) return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX; /* Special case: initial '.' is RHS match */ if (!baseat && (*baseptr == '.')) { if (eml->length > base->length) { emlptr += eml->length - base->length; if (ia5casecmp(baseptr, emlptr) == 0) return X509_V_OK; } return X509_V_ERR_PERMITTED_VIOLATION; } /* If we have anything before '@' match local part */ if (baseat) { if (baseat != baseptr) { if ((baseat - baseptr) != (emlat - emlptr)) return X509_V_ERR_PERMITTED_VIOLATION; /* Case sensitive match of local part */ if (strncmp(baseptr, emlptr, emlat - emlptr)) return X509_V_ERR_PERMITTED_VIOLATION; } /* Position base after '@' */ baseptr = baseat + 1; } emlptr = emlat + 1; /* Just have hostname left to match: case insensitive */ if (ia5casecmp(baseptr, emlptr)) return X509_V_ERR_PERMITTED_VIOLATION; return X509_V_OK; } static int nc_uri(ASN1_IA5STRING *uri, ASN1_IA5STRING *base) { const char *baseptr = (char *)base->data; const char *hostptr = (char *)uri->data; const char *p = strchr(hostptr, ':'); int hostlen; /* Check for foo:// and skip past it */ if (p == NULL || p[1] != '/' || p[2] != '/') return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX; hostptr = p + 3; /* Determine length of hostname part of URI */ /* Look for a port indicator as end of hostname first */ p = strchr(hostptr, ':'); /* Otherwise look for trailing slash */ if (p == NULL) p = strchr(hostptr, '/'); if (p == NULL) hostlen = strlen(hostptr); else hostlen = p - hostptr; if (hostlen == 0) return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX; /* Special case: initial '.' is RHS match */ if (*baseptr == '.') { if (hostlen > base->length) { p = hostptr + hostlen - base->length; if (ia5ncasecmp(p, baseptr, base->length) == 0) return X509_V_OK; } return X509_V_ERR_PERMITTED_VIOLATION; } if ((base->length != (int)hostlen) || ia5ncasecmp(hostptr, baseptr, hostlen)) return X509_V_ERR_PERMITTED_VIOLATION; return X509_V_OK; } static int nc_ip(ASN1_OCTET_STRING *ip, ASN1_OCTET_STRING *base) { int hostlen, baselen, i; unsigned char *hostptr, *baseptr, *maskptr; hostptr = ip->data; hostlen = ip->length; baseptr = base->data; baselen = base->length; /* Invalid if not IPv4 or IPv6 */ if (!((hostlen == 4) || (hostlen == 16))) return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX; if (!((baselen == 8) || (baselen == 32))) return X509_V_ERR_UNSUPPORTED_NAME_SYNTAX; /* Do not match IPv4 with IPv6 */ if (hostlen * 2 != baselen) return X509_V_ERR_PERMITTED_VIOLATION; maskptr = base->data + hostlen; /* Considering possible not aligned base ipAddress */ /* Not checking for wrong mask definition: i.e.: 255.0.255.0 */ for (i = 0; i < hostlen; i++) if ((hostptr[i] & maskptr[i]) != (baseptr[i] & maskptr[i])) return X509_V_ERR_PERMITTED_VIOLATION; return X509_V_OK; }