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Re: [PATCH v7 4/5] crypto: Add tls-cipher-suites object
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From: |
Laszlo Ersek |
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Subject: |
Re: [PATCH v7 4/5] crypto: Add tls-cipher-suites object |
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Date: |
Fri, 29 May 2020 13:17:40 +0200 |
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User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 |
On 05/29/20 13:09, Laszlo Ersek wrote:
> On 05/28/20 19:31, Philippe Mathieu-Daudé wrote:
>> Example of use to dump:
>>
>> $ 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 <philmd@redhat.com>
>> ---
>> v7:
>> - Use Laszlo's loop with enum mode (lersek)
>
> Nice improvement with the enum, thanks!
>
>> - Convert debug printf to trace events (danpb)
>> - Use buildsys CONFIG_GNUTLS instead of C ifdef'ry (danpb)
>> ---
>> include/crypto/tls-cipher-suites.h | 38 +++++++++
>> crypto/tls-cipher-suites.c | 127 +++++++++++++++++++++++++++++
>> crypto/Makefile.objs | 1 +
>> crypto/trace-events | 5 ++
>> 4 files changed, 171 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..20a7c74edf
>> --- /dev/null
>> +++ b/include/crypto/tls-cipher-suites.h
>> @@ -0,0 +1,38 @@
>> +/*
>> + * QEMU TLS Cipher Suites
>> + *
>> + * Copyright (c) 2019 Red Hat, Inc.
>> + *
>> + * Author: Philippe Mathieu-Daudé <philmd@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 <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 "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..c07a752b50 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"
>>
>
> (1) It feels like we should insert one space character right after
> "data:", and another space character right after "version:". I think
> that makes things easier to read and possibly to parse. It also seems a
> bit more idiomatic with the rest of the trace messages.
>
> Anyway, I don't insist, up to you.
>
> (2) We need an actual commit message for this patch. How about the
> following -- I have liberally stolen and edited comments that Daniel
> made earlier in the Red Hat Bugzilla:
>
> ---v--- ---v--- ---v--- ---v---
> 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 libary 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 firmware, via
*guest* firmware -- sorry about the omission!
> 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
Ditto.
Thanks,
Laszlo
> 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).
> ---^--- ---^--- ---^--- ---^---
>
> (3) I think I have now at least formed an idea about where we should
> document -fw_cfg / "gen_id" in the *manual*.
>
> The various -object types are already documented extensively; namely in
> section "Generic object creation". Thus, I think we should document
> "tls-cipher-suites" there -- near the already existent "-object tls-*"
> ones.
>
> I suggest including a manual update to that effect. I think we can mostly
> copy the suggested commit message into the manual as well.
>
> And then, we can include the new "-fw_cfg" command line option (with
> "gen_id") *right there*. Consequently, we won't need to modify the
> existent "-fw_cfg" documentation bits (about "file" and "string") under
> section "Debug/Expert options".
>
> Dan: please comment!
>
> Thanks,
> Laszlo
>