qemu-e2k/crypto/tls-cipher-suites.c

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crypto: Add tls-cipher-suites object On the host OS, various aspects of TLS operation are configurable. In particular it is possible for the sysadmin to control the TLS cipher/protocol algorithms that applications are permitted to use. * Any given crypto library has a built-in default priority list defined by the distro maintainer of the library package (or by upstream). * The "crypto-policies" RPM (or equivalent host OS package) provides a config file such as "/etc/crypto-policies/config", where the sysadmin can set a high level (library-independent) policy. The "update-crypto-policies --set" command (or equivalent) is used to translate the global policy to individual library representations, producing files such as "/etc/crypto-policies/back-ends/*.config". The generated files, if present, are loaded by the various crypto libraries to override their own built-in defaults. For example, the GNUTLS library may read "/etc/crypto-policies/back-ends/gnutls.config". * A management application (or the QEMU user) may overide the system-wide crypto-policies config via their own config, if they need to diverge from the former. Thus the priority order is "QEMU user config" > "crypto-policies system config" > "library built-in config". Introduce the "tls-cipher-suites" object for exposing the ordered list of permitted TLS cipher suites from the host side to the guest firmware, via fw_cfg. The list is represented as an array of bytes. The priority at which the host-side policy is retrieved is given by the "priority" property of the new object type. For example, "priority=@SYSTEM" may be used to refer to "/etc/crypto-policies/back-ends/gnutls.config" (given that QEMU uses GNUTLS). The firmware uses the IANA_TLS_CIPHER array for configuring guest-side TLS, for example in UEFI HTTPS Boot. [Description from Daniel P. Berrangé, edited by Laszlo Ersek.] Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com> Reviewed-by: Daniel P. Berrangé <berrange@redhat.com> Acked-by: Laszlo Ersek <lersek@redhat.com> Message-Id: <20200623172726.21040-2-philmd@redhat.com>
2018-10-11 20:21:11 +02:00
/*
* QEMU TLS Cipher Suites
*
* Copyright (c) 2018-2020 Red Hat, Inc.
*
* Author: Philippe Mathieu-Daudé <philmd@redhat.com>
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
#include "qemu/osdep.h"
#include "qapi/error.h"
#include "qom/object_interfaces.h"
#include "crypto/tlscreds.h"
#include "crypto/tls-cipher-suites.h"
#include "trace.h"
/*
* IANA registered TLS ciphers:
* https://www.iana.org/assignments/tls-parameters/tls-parameters.xhtml#tls-parameters-4
*/
typedef struct {
uint8_t data[2];
} QEMU_PACKED IANA_TLS_CIPHER;
GByteArray *qcrypto_tls_cipher_suites_get_data(QCryptoTLSCipherSuites *obj,
Error **errp)
{
QCryptoTLSCreds *creds = QCRYPTO_TLS_CREDS(obj);
gnutls_priority_t pcache;
GByteArray *byte_array;
const char *err;
size_t i;
int ret;
trace_qcrypto_tls_cipher_suite_priority(creds->priority);
ret = gnutls_priority_init(&pcache, creds->priority, &err);
if (ret < 0) {
error_setg(errp, "Syntax error using priority '%s': %s",
creds->priority, gnutls_strerror(ret));
return NULL;
}
byte_array = g_byte_array_new();
for (i = 0;; i++) {
int ret;
unsigned idx;
const char *name;
IANA_TLS_CIPHER cipher;
gnutls_protocol_t protocol;
const char *version;
ret = gnutls_priority_get_cipher_suite_index(pcache, i, &idx);
if (ret == GNUTLS_E_REQUESTED_DATA_NOT_AVAILABLE) {
break;
}
if (ret == GNUTLS_E_UNKNOWN_CIPHER_SUITE) {
continue;
}
name = gnutls_cipher_suite_info(idx, (unsigned char *)&cipher,
NULL, NULL, NULL, &protocol);
if (name == NULL) {
continue;
}
version = gnutls_protocol_get_name(protocol);
g_byte_array_append(byte_array, cipher.data, 2);
trace_qcrypto_tls_cipher_suite_info(cipher.data[0],
cipher.data[1],
version, name);
}
trace_qcrypto_tls_cipher_suite_count(byte_array->len);
gnutls_priority_deinit(pcache);
return byte_array;
}
static void qcrypto_tls_cipher_suites_complete(UserCreatable *uc,
Error **errp)
{
QCryptoTLSCreds *creds = QCRYPTO_TLS_CREDS(uc);
if (!creds->priority) {
error_setg(errp, "'priority' property is not set");
return;
}
}
static void qcrypto_tls_cipher_suites_class_init(ObjectClass *oc, void *data)
{
UserCreatableClass *ucc = USER_CREATABLE_CLASS(oc);
ucc->complete = qcrypto_tls_cipher_suites_complete;
}
static const TypeInfo qcrypto_tls_cipher_suites_info = {
.parent = TYPE_QCRYPTO_TLS_CREDS,
.name = TYPE_QCRYPTO_TLS_CIPHER_SUITES,
.instance_size = sizeof(QCryptoTLSCreds),
.class_size = sizeof(QCryptoTLSCredsClass),
.class_init = qcrypto_tls_cipher_suites_class_init,
.interfaces = (InterfaceInfo[]) {
{ TYPE_USER_CREATABLE },
{ }
}
};
static void qcrypto_tls_cipher_suites_register_types(void)
{
type_register_static(&qcrypto_tls_cipher_suites_info);
}
type_init(qcrypto_tls_cipher_suites_register_types);