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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [qemu-xen staging] crypto: Add tls-cipher-suites object
commit 993aec27aa39aa90f89f227d8f82cc1f8062386e
Author: Philippe Mathieu-Daudé <philmd@xxxxxxxxxx>
AuthorDate: Thu Oct 11 20:21:11 2018 +0200
Commit: Philippe Mathieu-Daudé <philmd@xxxxxxxxxx>
CommitDate: Fri Jul 3 18:16:01 2020 +0200
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@xxxxxxxxxx>
Reviewed-by: Daniel P. Berrangé <berrange@xxxxxxxxxx>
Acked-by: Laszlo Ersek <lersek@xxxxxxxxxx>
Message-Id: <20200623172726.21040-2-philmd@xxxxxxxxxx>
---
crypto/Makefile.objs | 1 +
crypto/tls-cipher-suites.c | 115 +++++++++++++++++++++++++++++++++++++
crypto/trace-events | 5 ++
include/crypto/tls-cipher-suites.h | 39 +++++++++++++
qemu-options.hx | 19 ++++++
5 files changed, 179 insertions(+)
diff --git a/crypto/Makefile.objs b/crypto/Makefile.objs
index 707c02ad37..f1965b1a68 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/tls-cipher-suites.c b/crypto/tls-cipher-suites.c
new file mode 100644
index 0000000000..a4e0f84307
--- /dev/null
+++ b/crypto/tls-cipher-suites.c
@@ -0,0 +1,115 @@
+/*
+ * QEMU TLS Cipher Suites
+ *
+ * Copyright (c) 2018-2020 Red Hat, Inc.
+ *
+ * Author: Philippe Mathieu-Daudé <philmd@xxxxxxxxxx>
+ *
+ * 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);
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/include/crypto/tls-cipher-suites.h
b/include/crypto/tls-cipher-suites.h
new file mode 100644
index 0000000000..28b3a73ce1
--- /dev/null
+++ b/include/crypto/tls-cipher-suites.h
@@ -0,0 +1,39 @@
+/*
+ * QEMU TLS Cipher Suites Registry (RFC8447)
+ *
+ * Copyright (c) 2018-2020 Red Hat, Inc.
+ *
+ * Author: Philippe Mathieu-Daudé <philmd@xxxxxxxxxx>
+ *
+ * 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)
+
+typedef struct QCryptoTLSCipherSuites {
+ /* <private> */
+ QCryptoTLSCreds parent_obj;
+ /* <public> */
+} QCryptoTLSCipherSuites;
+
+/**
+ * qcrypto_tls_cipher_suites_get_data:
+ * @obj: pointer to a TLS cipher suites object
+ * @errp: pointer to a NULL-initialized error object
+ *
+ * Returns: reference to a byte array containing the data.
+ * The caller should release the reference when no longer
+ * required.
+ */
+GByteArray *qcrypto_tls_cipher_suites_get_data(QCryptoTLSCipherSuites *obj,
+ Error **errp);
+
+#endif /* QCRYPTO_TLSCIPHERSUITES_H */
diff --git a/qemu-options.hx b/qemu-options.hx
index 196f468786..ecc4658e1f 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -4567,6 +4567,25 @@ 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 frontends 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
--
generated by git-patchbot for /home/xen/git/qemu-xen.git#staging
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