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Tue, 16 Jun 2020 16:32:57 +0000 (UTC) Date: Tue, 16 Jun 2020 17:32:54 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= Subject: Re: [PATCH v9 4/5] crypto: Add tls-cipher-suites object Message-ID: <20200616163254.GQ550360@redhat.com> References: <20200615103457.25282-1-philmd@redhat.com> <20200615103457.25282-5-philmd@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20200615103457.25282-5-philmd@redhat.com> User-Agent: Mutt/1.14.0 (2020-05-02) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Received-SPF: pass client-ip=207.211.31.81; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/06/16 02:45:57 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, URIBL_BLOCKED=0.001 autolearn=_AUTOLEARN X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Cc: Paolo Bonzini , Laszlo Ersek , qemu-devel@nongnu.org, Gerd Hoffmann Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Mon, Jun 15, 2020 at 12:34:56PM +0200, 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\* > > Reviewed-by: Laszlo Ersek > Signed-off-by: Philippe Mathieu-Daudé > --- > v9: Replaced 'backends' -> 'frontends' (lersek) > --- > 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 > + * > + * 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 { > + /* */ > + QCryptoTLSCreds parent_obj; > + > + /* */ > + IANA_TLS_CIPHER *cipher_list; > + unsigned cipher_count; There's no benefit to storing in a IANA_TLS_CIPHER struct that I can see. If you use a GByteArray for storing the data to match my suggestion from the previous patch, then..... > +} 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 > + * > + * 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; ....this extra loop is not neccessary.... > + > + 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; ...you can just call g_byte_array_append() here. GByteArray will efficiently grow as needed - it won't do O(N) re-allocs. > + } > + 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); > +} Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|