On 06/09/20 19:07, Philippe Mathieu-Daudé wrote: > 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
(1) I think the word "backends" should be replaced by "frontends". The "id" property is generally used with backends. And then frontends refer to backend identifiers with properties that are usually *not* called "id" (but "bus", "chardev", "drive", "netdev" etc). In this case, "tls-cipher-suites" is the back-end, and fw_cfg is the front-end. (If I'm wrong about this, please ignore the above.) Reviewed-by: Laszlo Ersek <ler...@redhat.com> Thanks Laszlo > + 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 >
