ssl: Validate hostnames

Closes #524
This commit is contained in:
TingPing 2014-11-19 21:43:01 -05:00
parent ebaaf466bf
commit c9b63f7f9b
3 changed files with 219 additions and 2 deletions

View File

@ -723,9 +723,22 @@ ssl_do_connect (server * serv)
switch (verify_error)
{
case X509_V_OK:
{
X509 *cert = SSL_get_peer_certificate (serv->ssl);
int hostname_err;
if ((hostname_err = _SSL_check_hostname(cert, serv->hostname)) != 0)
{
snprintf (buf, sizeof (buf), "* Verify E: Failed to validate hostname? (%d)%s",
hostname_err, serv->accept_invalid_cert ? " -- Ignored" : "");
if (serv->accept_invalid_cert)
EMIT_SIGNAL (XP_TE_SSLMESSAGE, serv->server_session, buf, NULL, NULL, NULL, 0);
else
goto conn_fail;
}
break;
}
/* snprintf (buf, sizeof (buf), "* Verify OK (?)"); */
/* EMIT_SIGNAL (XP_TE_SSLMESSAGE, serv->server_session, buf, NULL, NULL, NULL, 0); */
break;
case X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT_LOCALLY:
case X509_V_ERR_UNABLE_TO_VERIFY_LEAF_SIGNATURE:
case X509_V_ERR_DEPTH_ZERO_SELF_SIGNED_CERT:
@ -744,6 +757,7 @@ ssl_do_connect (server * serv)
snprintf (buf, sizeof (buf), "%s.? (%d)",
X509_verify_cert_error_string (verify_error),
verify_error);
conn_fail:
EMIT_SIGNAL (XP_TE_CONNFAIL, serv->server_session, buf, NULL, NULL,
NULL, 0);

View File

@ -25,6 +25,7 @@
#include "inet.h" /* make it first to avoid macro redefinitions */
#include <openssl/ssl.h> /* SSL_() */
#include <openssl/err.h> /* ERR_() */
#include <openssl/x509v3.h>
#ifdef WIN32
#include <openssl/rand.h> /* RAND_seed() */
#endif
@ -35,6 +36,7 @@
#include <glib.h>
#include <glib/gprintf.h>
#include <gio/gio.h>
#include "util.h"
/* If openssl was built without ec */
@ -339,3 +341,204 @@ _SSL_close (SSL * ssl)
SSL_free (ssl);
ERR_remove_state (0); /* free state buffer */
}
/* Hostname validation code based on OpenBSD's libtls. */
static int
_SSL_match_hostname (const char *cert_hostname, const char *hostname)
{
const char *cert_domain, *domain, *next_dot;
if (g_ascii_strcasecmp (cert_hostname, hostname) == 0)
return 0;
/* Wildcard match? */
if (cert_hostname[0] == '*')
{
/*
* Valid wildcards:
* - "*.domain.tld"
* - "*.sub.domain.tld"
* - etc.
* Reject "*.tld".
* No attempt to prevent the use of eg. "*.co.uk".
*/
cert_domain = &cert_hostname[1];
/* Disallow "*" */
if (cert_domain[0] == '\0')
return -1;
/* Disallow "*foo" */
if (cert_domain[0] != '.')
return -1;
/* Disallow "*.." */
if (cert_domain[1] == '.')
return -1;
next_dot = strchr (&cert_domain[1], '.');
/* Disallow "*.bar" */
if (next_dot == NULL)
return -1;
/* Disallow "*.bar.." */
if (next_dot[1] == '.')
return -1;
domain = strchr (hostname, '.');
/* No wildcard match against a hostname with no domain part. */
if (domain == NULL || strlen(domain) == 1)
return -1;
if (g_ascii_strcasecmp (cert_domain, domain) == 0)
return 0;
}
return -1;
}
static int
_SSL_check_subject_altname (X509 *cert, const char *host)
{
STACK_OF(GENERAL_NAME) *altname_stack = NULL;
GInetAddress *addr;
GSocketFamily family;
int type = GEN_DNS;
int count, i;
int rv = -1;
altname_stack = X509_get_ext_d2i (cert, NID_subject_alt_name, NULL, NULL);
if (altname_stack == NULL)
return -1;
addr = g_inet_address_new_from_string (host);
if (addr != NULL)
{
family = g_inet_address_get_family (addr);
if (family == G_SOCKET_FAMILY_IPV4 || family == G_SOCKET_FAMILY_IPV6)
type = GEN_IPADD;
}
count = sk_GENERAL_NAME_num(altname_stack);
for (i = 0; i < count; i++)
{
GENERAL_NAME *altname;
altname = sk_GENERAL_NAME_value (altname_stack, i);
if (altname->type != type)
continue;
if (type == GEN_DNS)
{
unsigned char *data;
int format;
format = ASN1_STRING_type (altname->d.dNSName);
if (format == V_ASN1_IA5STRING)
{
data = ASN1_STRING_data (altname->d.dNSName);
if (ASN1_STRING_length (altname->d.dNSName) != (int)strlen(data))
{
g_warning("NUL byte in subjectAltName, probably a malicious certificate.\n");
rv = -2;
break;
}
if (_SSL_match_hostname (data, host) == 0)
{
rv = 0;
break;
}
}
else
g_warning ("unhandled subjectAltName dNSName encoding (%d)\n", format);
}
else if (type == GEN_IPADD)
{
unsigned char *data;
const guint8 *addr_bytes;
int datalen, addr_len;
datalen = ASN1_STRING_length (altname->d.iPAddress);
data = ASN1_STRING_data (altname->d.iPAddress);
addr_bytes = g_inet_address_to_bytes (addr);
addr_len = (int)g_inet_address_get_native_size (addr);
if (datalen == addr_len && memcmp (data, addr_bytes, addr_len) == 0)
{
rv = 0;
break;
}
}
}
if (addr != NULL)
g_object_unref (addr);
sk_GENERAL_NAME_free (altname_stack);
return rv;
}
static int
_SSL_check_common_name (X509 *cert, const char *host)
{
X509_NAME *name;
char *common_name = NULL;
int common_name_len;
int rv = -1;
GInetAddress *addr;
name = X509_get_subject_name (cert);
if (name == NULL)
return -1;
common_name_len = X509_NAME_get_text_by_NID (name, NID_commonName, NULL, 0);
if (common_name_len < 0)
return -1;
common_name = calloc (common_name_len + 1, 1);
if (common_name == NULL)
return -1;
X509_NAME_get_text_by_NID (name, NID_commonName, common_name, common_name_len + 1);
/* NUL bytes in CN? */
if (common_name_len != (int)strlen(common_name))
{
g_warning ("NUL byte in Common Name field, probably a malicious certificate.\n");
rv = -2;
goto out;
}
if ((addr = g_inet_address_new_from_string (host)) != NULL)
{
/*
* We don't want to attempt wildcard matching against IP
* addresses, so perform a simple comparison here.
*/
if (g_strcmp0 (common_name, host) == 0)
rv = 0;
else
rv = -1;
g_object_unref (addr);
}
else if (_SSL_match_hostname (common_name, host) == 0)
rv = 0;
out:
free(common_name);
return rv;
}
int
_SSL_check_hostname (X509 *cert, const char *host)
{
int rv;
rv = _SSL_check_subject_altname (cert, host);
if (rv == 0 || rv == -2)
return rv;
return _SSL_check_common_name (cert, host);
}

View File

@ -52,7 +52,7 @@ char *_SSL_set_verify (SSL_CTX *ctx, void *(verify_callback), char *cacert);
int SSL_get_fd(SSL *);
*/
void _SSL_close (SSL * ssl);
int _SSL_check_hostname(X509 *cert, const char *host);
int _SSL_get_cert_info (struct cert_info *cert_info, SSL * ssl);
struct chiper_info *_SSL_get_cipher_info (SSL * ssl);