/*
- * Copyright 2003-2017 The OpenSSL Project Authors. All Rights Reserved.
+ * Copyright 2003-2018 The OpenSSL Project Authors. All Rights Reserved.
*
* Licensed under the OpenSSL license (the "License"). You may not use
* this file except in compliance with the License. You can obtain a copy
#include <openssl/asn1t.h>
#include <openssl/conf.h>
#include <openssl/x509v3.h>
+#include <openssl/bn.h>
#include "internal/x509_int.h"
#include "ext_dat.h"
}
+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;
- X509_NAME *nm;
-
+ 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;
- nm = X509_get_subject_name(x);
-
/* Process any commonName attributes in subject name */
for (i = -1;;) {
X509_NAME_ENTRY *ne;
- ASN1_STRING *hn;
+ 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);
- hn = X509_NAME_ENTRY_get_data(ne);
- /* Only process attributes that look like host names */
- if (asn1_valid_host(hn)) {
- unsigned char *h;
- int hlen = ASN1_STRING_to_UTF8(&h, hn);
- if (hlen <= 0)
- return X509_V_ERR_OUT_OF_MEM;
-
- stmp.length = hlen;
- stmp.data = h;
-
- r = nc_match(&gntmp, nc);
+ cn = X509_NAME_ENTRY_get_data(ne);
- OPENSSL_free(h);
+ /* Only process attributes that look like host names */
+ if ((r = cn2dnsid(cn, &idval, &idlen)) != X509_V_OK)
+ return r;
+ if (idlen == 0)
+ continue;
- if (r != X509_V_OK)
- return r;
- }
+ 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;
sub = sk_GENERAL_SUBTREE_value(nc->permittedSubtrees, i);
if (gen->type != sub->base->type)
continue;
- if (sub->minimum || sub->maximum)
+ 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)
sub = sk_GENERAL_SUBTREE_value(nc->excludedSubtrees, i);
if (gen->type != sub->base->type)
continue;
- if (sub->minimum || sub->maximum)
+ if (!nc_minmax_valid(sub))
return X509_V_ERR_SUBTREE_MINMAX;
r = nc_match_single(gen, sub->base);
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