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 IANA_TLS_CIPHER objects. The firmware uses the IANA_TLS_CIPHER
array for configuring guest-side TLS, for example in UEFI HTTPS
Boot.
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).
[Description from Daniel P. Berrangé, edited by Laszlo Ersek.]
Example of use to dump the cipher suites:
$ qemu-system-x86_64 -S \
-object tls-cipher-suites,id=mysuite,priority=@SYSTEM \
-trace qcrypto\*
1590664444.197123:qcrypto_tls_cipher_suite_priority priority: @SYSTEM
1590664444.197219:qcrypto_tls_cipher_suite_info data=[0x13,0x02]
version=TLS1.3 name=TLS_AES_256_GCM_SHA384
1590664444.197228:qcrypto_tls_cipher_suite_info data=[0x13,0x03]
version=TLS1.3 name=TLS_CHACHA20_POLY1305_SHA256
1590664444.197233:qcrypto_tls_cipher_suite_info data=[0x13,0x01]
version=TLS1.3 name=TLS_AES_128_GCM_SHA256
1590664444.197236:qcrypto_tls_cipher_suite_info data=[0x13,0x04]
version=TLS1.3 name=TLS_AES_128_CCM_SHA256
1590664444.197240:qcrypto_tls_cipher_suite_info data=[0xc0,0x30]
version=TLS1.2 name=TLS_ECDHE_RSA_AES_256_GCM_SHA384
1590664444.197245:qcrypto_tls_cipher_suite_info data=[0xcc,0xa8]
version=TLS1.2 name=TLS_ECDHE_RSA_CHACHA20_POLY1305
1590664444.197250:qcrypto_tls_cipher_suite_info data=[0xc0,0x14]
version=TLS1.0 name=TLS_ECDHE_RSA_AES_256_CBC_SHA1
1590664444.197254:qcrypto_tls_cipher_suite_info data=[0xc0,0x2f]
version=TLS1.2 name=TLS_ECDHE_RSA_AES_128_GCM_SHA256
1590664444.197258:qcrypto_tls_cipher_suite_info data=[0xc0,0x13]
version=TLS1.0 name=TLS_ECDHE_RSA_AES_128_CBC_SHA1
1590664444.197261:qcrypto_tls_cipher_suite_info data=[0xc0,0x2c]
version=TLS1.2 name=TLS_ECDHE_ECDSA_AES_256_GCM_SHA384
1590664444.197266:qcrypto_tls_cipher_suite_info data=[0xcc,0xa9]
version=TLS1.2 name=TLS_ECDHE_ECDSA_CHACHA20_POLY1305
1590664444.197270:qcrypto_tls_cipher_suite_info data=[0xc0,0xad]
version=TLS1.2 name=TLS_ECDHE_ECDSA_AES_256_CCM
1590664444.197274:qcrypto_tls_cipher_suite_info data=[0xc0,0x0a]
version=TLS1.0 name=TLS_ECDHE_ECDSA_AES_256_CBC_SHA1
1590664444.197278:qcrypto_tls_cipher_suite_info data=[0xc0,0x2b]
version=TLS1.2 name=TLS_ECDHE_ECDSA_AES_128_GCM_SHA256
1590664444.197283:qcrypto_tls_cipher_suite_info data=[0xc0,0xac]
version=TLS1.2 name=TLS_ECDHE_ECDSA_AES_128_CCM
1590664444.197287:qcrypto_tls_cipher_suite_info data=[0xc0,0x09]
version=TLS1.0 name=TLS_ECDHE_ECDSA_AES_128_CBC_SHA1
1590664444.197291:qcrypto_tls_cipher_suite_info data=[0x00,0x9d]
version=TLS1.2 name=TLS_RSA_AES_256_GCM_SHA384
1590664444.197296:qcrypto_tls_cipher_suite_info data=[0xc0,0x9d]
version=TLS1.2 name=TLS_RSA_AES_256_CCM
1590664444.197300:qcrypto_tls_cipher_suite_info data=[0x00,0x35]
version=TLS1.0 name=TLS_RSA_AES_256_CBC_SHA1
1590664444.197304:qcrypto_tls_cipher_suite_info data=[0x00,0x9c]
version=TLS1.2 name=TLS_RSA_AES_128_GCM_SHA256
1590664444.197308:qcrypto_tls_cipher_suite_info data=[0xc0,0x9c]
version=TLS1.2 name=TLS_RSA_AES_128_CCM
1590664444.197312:qcrypto_tls_cipher_suite_info data=[0x00,0x2f]
version=TLS1.0 name=TLS_RSA_AES_128_CBC_SHA1
1590664444.197316:qcrypto_tls_cipher_suite_info data=[0x00,0x9f]
version=TLS1.2 name=TLS_DHE_RSA_AES_256_GCM_SHA384
1590664444.197320:qcrypto_tls_cipher_suite_info data=[0xcc,0xaa]
version=TLS1.2 name=TLS_DHE_RSA_CHACHA20_POLY1305
1590664444.197325:qcrypto_tls_cipher_suite_info data=[0xc0,0x9f]
version=TLS1.2 name=TLS_DHE_RSA_AES_256_CCM
1590664444.197329:qcrypto_tls_cipher_suite_info data=[0x00,0x39]
version=TLS1.0 name=TLS_DHE_RSA_AES_256_CBC_SHA1
1590664444.197333:qcrypto_tls_cipher_suite_info data=[0x00,0x9e]
version=TLS1.2 name=TLS_DHE_RSA_AES_128_GCM_SHA256
1590664444.197337:qcrypto_tls_cipher_suite_info data=[0xc0,0x9e]
version=TLS1.2 name=TLS_DHE_RSA_AES_128_CCM
1590664444.197341:qcrypto_tls_cipher_suite_info data=[0x00,0x33]
version=TLS1.0 name=TLS_DHE_RSA_AES_128_CBC_SHA1
1590664444.197345:qcrypto_tls_cipher_suite_count count: 29
Signed-off-by: Philippe Mathieu-Daudé <phi...@redhat.com>
---
v8: addressed Laszlo's comments
- updated trace events format to match other crypto ones
- inserted Daniel/Laszlo commit description
- describe object in qemu-options.hx
---
include/crypto/tls-cipher-suites.h | 38 +++++++++
crypto/tls-cipher-suites.c | 127 +++++++++++++++++++++++++++++
crypto/Makefile.objs | 1 +
crypto/trace-events | 5 ++
qemu-options.hx | 19 +++++
5 files changed, 190 insertions(+)
create mode 100644 include/crypto/tls-cipher-suites.h
create mode 100644 crypto/tls-cipher-suites.c
diff --git a/include/crypto/tls-cipher-suites.h
b/include/crypto/tls-cipher-suites.h
new file mode 100644
index 0000000000..3848393a20
--- /dev/null
+++ b/include/crypto/tls-cipher-suites.h
@@ -0,0 +1,38 @@
+/*
+ * QEMU TLS Cipher Suites Registry (RFC8447)
+ *
+ * Copyright (c) 2019 Red Hat, Inc.
+ *
+ * Author: Philippe Mathieu-Daudé <phi...@redhat.com>
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#ifndef QCRYPTO_TLSCIPHERSUITES_H
+#define QCRYPTO_TLSCIPHERSUITES_H
+
+#include "qom/object.h"
+#include "crypto/tlscreds.h"
+
+#define TYPE_QCRYPTO_TLS_CIPHER_SUITES "tls-cipher-suites"
+#define QCRYPTO_TLS_CIPHER_SUITES(obj) \
+ OBJECT_CHECK(QCryptoTLSCipherSuites, (obj), TYPE_QCRYPTO_TLS_CIPHER_SUITES)
+
+/*
+ * 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;
+
+typedef struct QCryptoTLSCipherSuites {
+ /* <private> */
+ QCryptoTLSCreds parent_obj;
+
+ /* <public> */
+ IANA_TLS_CIPHER *cipher_list;
+ unsigned cipher_count;
+} QCryptoTLSCipherSuites;
+
+#endif /* QCRYPTO_TLSCIPHERSUITES_H */
diff --git a/crypto/tls-cipher-suites.c b/crypto/tls-cipher-suites.c
new file mode 100644
index 0000000000..f02a041f9a
--- /dev/null
+++ b/crypto/tls-cipher-suites.c
@@ -0,0 +1,127 @@
+/*
+ * QEMU TLS Cipher Suites
+ *
+ * Copyright (c) 2019 Red Hat, Inc.
+ *
+ * Author: Philippe Mathieu-Daudé <phi...@redhat.com>
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "qemu/osdep.h"
+#include "qapi/error.h"
+#include "qom/object_interfaces.h"
+#include "qemu/error-report.h"
+#include "crypto/tlscreds.h"
+#include "crypto/tls-cipher-suites.h"
+#include "trace.h"
+
+static void parse_cipher_suites(QCryptoTLSCipherSuites *s,
+ const char *priority_name, Error **errp)
+{
+ int ret;
+ const char *err;
+ gnutls_priority_t pcache;
+ enum { M_ENUMERATE, M_GENERATE, M_DONE } mode;
+
+ assert(priority_name);
+ trace_qcrypto_tls_cipher_suite_priority(priority_name);
+ ret = gnutls_priority_init(&pcache, priority_name, &err);
+ if (ret < 0) {
+ error_setg(errp, "Syntax error using priority '%s': %s",
+ priority_name, gnutls_strerror(ret));
+ return;
+ }
+
+ for (mode = M_ENUMERATE; mode < M_DONE; mode++) {
+ size_t i;
+
+ for (i = 0;; i++) {
+ int ret;
+ unsigned idx;
+ const char *name;
+ IANA_TLS_CIPHER cipher;
+ gnutls_protocol_t protocol;
+
+ 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;
+ }
+
+ if (mode == M_GENERATE) {
+ const char *version;
+
+ version = gnutls_protocol_get_name(protocol);
+ trace_qcrypto_tls_cipher_suite_info(cipher.data[0],
+ cipher.data[1],
+ version, name);
+ s->cipher_list[s->cipher_count] = cipher;
+ }
+ s->cipher_count++;
+ }
+
+ if (mode == M_ENUMERATE) {
+ if (s->cipher_count == 0) {
+ break;
+ }
+ s->cipher_list = g_new(IANA_TLS_CIPHER, s->cipher_count);
+ s->cipher_count = 0;
+ }
+ }
+ trace_qcrypto_tls_cipher_suite_count(s->cipher_count);
+ gnutls_priority_deinit(pcache);
+}
+
+static void qcrypto_tls_cipher_suites_complete(UserCreatable *uc, Error **errp)
+{
+ QCryptoTLSCreds *s = QCRYPTO_TLS_CREDS(uc);
+
+ if (!s->priority) {
+ error_setg(errp, "'priority' property is not set");
+ return;
+ }
+ parse_cipher_suites(QCRYPTO_TLS_CIPHER_SUITES(s), s->priority, errp);
+}
+
+static void qcrypto_tls_cipher_suites_finalize(Object *obj)
+{
+ QCryptoTLSCipherSuites *s = QCRYPTO_TLS_CIPHER_SUITES(obj);
+
+ g_free(s->cipher_list);
+}
+
+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(QCryptoTLSCipherSuites),
+ .instance_finalize = qcrypto_tls_cipher_suites_finalize,
+ .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);
diff --git a/crypto/Makefile.objs b/crypto/Makefile.objs
index c2a371b0b4..1c1b5e21ff 100644
--- a/crypto/Makefile.objs
+++ b/crypto/Makefile.objs
@@ -13,6 +13,7 @@ crypto-obj-y += cipher.o
crypto-obj-$(CONFIG_AF_ALG) += afalg.o
crypto-obj-$(CONFIG_AF_ALG) += cipher-afalg.o
crypto-obj-$(CONFIG_AF_ALG) += hash-afalg.o
+crypto-obj-$(CONFIG_GNUTLS) += tls-cipher-suites.o
crypto-obj-y += tlscreds.o
crypto-obj-y += tlscredsanon.o
crypto-obj-y += tlscredspsk.o
diff --git a/crypto/trace-events b/crypto/trace-events
index 9e594d30e8..798b6067ab 100644
--- a/crypto/trace-events
+++ b/crypto/trace-events
@@ -21,3 +21,8 @@ qcrypto_tls_creds_x509_load_cert_list(void *creds, const char
*file) "TLS creds
# tlssession.c
qcrypto_tls_session_new(void *session, void *creds, const char *hostname,
const char *authzid, int endpoint) "TLS session new session=%p creds=%p
hostname=%s authzid=%s endpoint=%d"
qcrypto_tls_session_check_creds(void *session, const char *status) "TLS
session check creds session=%p status=%s"
+
+# tls-cipher-suites.c
+qcrypto_tls_cipher_suite_priority(const char *name) "priority: %s"
+qcrypto_tls_cipher_suite_info(uint8_t data0, uint8_t data1, const char
*version, const char *name) "data=[0x%02x,0x%02x] version=%s name=%s"
+qcrypto_tls_cipher_suite_count(unsigned count) "count: %u"
diff --git a/qemu-options.hx b/qemu-options.hx
index 93bde2bbc8..c74366d7cc 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -4566,6 +4566,25 @@ SRST
string as described at
https://gnutls.org/manual/html_node/Priority-Strings.html.
+ ``-object tls-cipher-suites,id=id,priority=priority``
+ Creates a TLS cipher suites object, which can be used to control
+ the TLS cipher/protocol algorithms that applications are permitted
+ to use.
+
+ The ``id`` parameter is a unique ID which backends will use to
+ access the ordered list of permitted TLS cipher suites from the
+ host.
+
+ The ``priority`` parameter allows to override the global default
+ priority used by gnutls. This can be useful if the system
+ administrator needs to use a weaker set of crypto priorities for
+ QEMU without potentially forcing the weakness onto all
+ applications. Or conversely if one wants wants a stronger
+ default for QEMU than for all other applications, they can do
+ this through this parameter. Its format is a gnutls priority
+ string as described at
+ https://gnutls.org/manual/html_node/Priority-Strings.html.
+
``-object
filter-buffer,id=id,netdev=netdevid,interval=t[,queue=all|rx|tx][,status=on|off][,position=head|tail|id=<id>][,insert=behind|before]``
Interval t can't be 0, this filter batches the packet delivery:
all packets arriving in a given interval on netdev netdevid are
--
2.21.3
