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/* -*- mode: c; c-basic-offset: 4; indent-tabs-mode: nil -*- */
/*
* Copyright 2014 Red Hat, Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
* IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
* PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
* OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "k5-int.h"
#include "k5-utf8.h"
#ifdef PROXY_TLS_IMPL_OPENSSL
#include <openssl/ssl.h>
#include <openssl/x509.h>
#include <openssl/x509v3.h>
#include "checkhost.h"
/* Return the passed-in character, lower-cased if it's an ASCII character. */
static inline char
ascii_tolower(char p)
{
if (KRB5_UPPER(p))
return p + ('a' - 'A');
return p;
}
/*
* Check a single label. If allow_wildcard is true, and the presented name
* includes a wildcard, return true and note that we matched a wildcard.
* Otherwise, for both the presented and expected values, do a case-insensitive
* comparison of ASCII characters, and a case-sensitive comparison of
* everything else.
*/
static krb5_boolean
label_match(const char *presented, size_t plen, const char *expected,
size_t elen, krb5_boolean allow_wildcard, krb5_boolean *wildcard)
{
unsigned int i;
if (allow_wildcard && plen == 1 && presented[0] == '*') {
*wildcard = TRUE;
return TRUE;
}
if (plen != elen)
return FALSE;
for (i = 0; i < elen; i++) {
if (ascii_tolower(presented[i]) != ascii_tolower(expected[i]))
return FALSE;
}
return TRUE;
}
/* Break up the two names and check them, label by label. */
static krb5_boolean
domain_match(const char *presented, size_t plen, const char *expected)
{
const char *p, *q, *r, *s;
int n_label;
krb5_boolean used_wildcard = FALSE;
n_label = 0;
p = presented;
r = expected;
while (p < presented + plen && *r != '\0') {
q = memchr(p, '.', plen - (p - presented));
if (q == NULL)
q = presented + plen;
s = r + strcspn(r, ".");
if (!label_match(p, q - p, r, s - r, n_label == 0, &used_wildcard))
return FALSE;
p = q < presented + plen ? q + 1 : q;
r = *s ? s + 1 : s;
n_label++;
}
if (used_wildcard && n_label <= 2)
return FALSE;
if (p == presented + plen && *r == '\0')
return TRUE;
return FALSE;
}
/* Fetch the list of subjectAltNames from a certificate. */
static GENERAL_NAMES *
get_cert_sans(X509 *x)
{
int ext;
X509_EXTENSION *san_ext;
ext = X509_get_ext_by_NID(x, NID_subject_alt_name, -1);
if (ext < 0)
return NULL;
san_ext = X509_get_ext(x, ext);
if (san_ext == NULL)
return NULL;
return X509V3_EXT_d2i(san_ext);
}
/* Fetch a CN value from the subjct name field, returning its length, or -1 if
* there is no subject name or it contains no CN value. */
static int
get_cert_cn(X509 *x, char *buf, size_t bufsize)
{
X509_NAME *name;
name = X509_get_subject_name(x);
if (name == NULL)
return -1;
return X509_NAME_get_text_by_NID(name, NID_commonName, buf, bufsize);
}
/*
* Return true if the passed-in expected IP address matches any of the names we
* can recover from the server certificate, false otherwise.
*/
krb5_boolean
k5_check_cert_address(X509 *x, const char *text)
{
char buf[1024];
GENERAL_NAMES *sans;
GENERAL_NAME *san = NULL;
ASN1_OCTET_STRING *ip;
krb5_boolean found_ip_san = FALSE, matched = FALSE;
int n_sans, i;
int name_length;
struct in_addr sin;
struct in6_addr sin6;
/* Parse the IP address into an octet string. */
ip = M_ASN1_OCTET_STRING_new();
if (ip == NULL)
return FALSE;
if (inet_pton(AF_INET, text, &sin)) {
M_ASN1_OCTET_STRING_set(ip, &sin, sizeof(sin));
} else if (inet_pton(AF_INET6, text, &sin6)) {
M_ASN1_OCTET_STRING_set(ip, &sin6, sizeof(sin6));
} else {
ASN1_OCTET_STRING_free(ip);
return FALSE;
}
/* Check for matches in ipaddress subjectAltName values. */
sans = get_cert_sans(x);
if (sans != NULL) {
n_sans = sk_GENERAL_NAME_num(sans);
for (i = 0; i < n_sans; i++) {
san = sk_GENERAL_NAME_value(sans, i);
if (san->type != GEN_IPADD)
continue;
found_ip_san = TRUE;
matched = (ASN1_OCTET_STRING_cmp(ip, san->d.iPAddress) == 0);
if (matched)
break;
}
sk_GENERAL_NAME_pop_free(sans, GENERAL_NAME_free);
}
ASN1_OCTET_STRING_free(ip);
if (found_ip_san)
return matched;
/* Check for a match against the CN value in the peer's subject name. */
name_length = get_cert_cn(x, buf, sizeof(buf));
if (name_length >= 0) {
/* Do a string compare to check if it's an acceptable value. */
return strlen(text) == (size_t)name_length &&
strncmp(text, buf, name_length) == 0;
}
/* We didn't find a match. */
return FALSE;
}
/*
* Return true if the passed-in expected name matches any of the names we can
* recover from a server certificate, false otherwise.
*/
krb5_boolean
k5_check_cert_servername(X509 *x, const char *expected)
{
char buf[1024];
GENERAL_NAMES *sans;
GENERAL_NAME *san = NULL;
unsigned char *dnsname;
krb5_boolean found_dns_san = FALSE, matched = FALSE;
int name_length, n_sans, i;
/* Check for matches in dnsname subjectAltName values. */
sans = get_cert_sans(x);
if (sans != NULL) {
n_sans = sk_GENERAL_NAME_num(sans);
for (i = 0; i < n_sans; i++) {
san = sk_GENERAL_NAME_value(sans, i);
if (san->type != GEN_DNS)
continue;
found_dns_san = TRUE;
dnsname = NULL;
name_length = ASN1_STRING_to_UTF8(&dnsname, san->d.dNSName);
if (dnsname == NULL)
continue;
matched = domain_match((char *)dnsname, name_length, expected);
OPENSSL_free(dnsname);
if (matched)
break;
}
sk_GENERAL_NAME_pop_free(sans, GENERAL_NAME_free);
}
if (matched)
return TRUE;
if (found_dns_san)
return matched;
/* Check for a match against the CN value in the peer's subject name. */
name_length = get_cert_cn(x, buf, sizeof(buf));
if (name_length >= 0)
return domain_match(buf, name_length, expected);
/* We didn't find a match. */
return FALSE;
}
#endif
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