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Mon, 23 Jun 2025 08:01:00 +0000 (UTC) Received: from redhat.com (unknown [10.42.28.95]) by mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 6E8C21956096; Mon, 23 Jun 2025 08:00:55 +0000 (UTC) Date: Mon, 23 Jun 2025 09:00:51 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Markus Armbruster Cc: Zhuoying Cai , thuth@redhat.com, richard.henderson@linaro.org, david@redhat.com, pbonzini@redhat.com, walling@linux.ibm.com, jjherne@linux.ibm.com, jrossi@linux.ibm.com, pasic@linux.ibm.com, borntraeger@linux.ibm.com, farman@linux.ibm.com, iii@linux.ibm.com, eblake@redhat.com, qemu-s390x@nongnu.org, qemu-devel@nongnu.org Subject: Re: [PATCH v3 02/28] crypto/x509-utils: Add helper functions for certificate store Message-ID: References: <20250604215657.528142-1-zycai@linux.ibm.com> <20250604215657.528142-3-zycai@linux.ibm.com> <87sejyskgj.fsf@pond.sub.org> <41e788ad-77e2-46d2-a384-2c8f524391c2@linux.ibm.com> <87wm99r3rh.fsf@pond.sub.org> <935581ef-1cb2-4e2f-9c3f-23203b556ca8@linux.ibm.com> <87ikkndlvv.fsf@pond.sub.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <87ikkndlvv.fsf@pond.sub.org> User-Agent: Mutt/2.2.14 (2025-02-20) X-Scanned-By: MIMEDefang 3.0 on 10.30.177.15 Received-SPF: pass client-ip=170.10.133.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com 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=-0.001, 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_H5=-1, RCVD_IN_MSPIKE_WL=-0.01, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Mon, Jun 23, 2025 at 08:15:16AM +0200, Markus Armbruster wrote: > Zhuoying Cai writes: > > > On 6/18/25 1:57 AM, Markus Armbruster wrote: > >> Zhuoying Cai writes: > >> > >>> On 6/17/25 6:58 AM, Markus Armbruster wrote: > >>>> Zhuoying Cai writes: > >>>> > >>>>> Add helper functions for x509 certificate which will be used in the next > >>>>> patch for the certificate store. > >>>>> > >>>>> Signed-off-by: Zhuoying Cai > >> > >> [...] > >> > >>>> Ignorant question: why are these QAPI enums? > >>>> > >>>> If they need to be QAPI enums, then I'll have some requests on the doc > >>>> comments. > >>>> > >>> > >>> Hi, thanks for the feedback. > >>> > >>> The helper functions in x509-utils.c either take QAPI enum values as > >>> parameters or return them. These enums are used later within QEMU. > >> > >> Let's look at the first one I found: > >> > >> int qcrypto_check_x509_cert_fmt(uint8_t *cert, size_t size, > >> QCryptoCertFmt fmt, Error **errp) > >> { > >> int rc; > >> int ret = -1; > >> gnutls_x509_crt_t crt; > >> gnutls_datum_t datum = {.data = cert, .size = size}; > >> > >> if (fmt >= G_N_ELEMENTS(qcrypto_to_gnutls_cert_fmt_map)) { > >> error_setg(errp, "Unknown certificate format"); > >> return ret; > >> } > >> > >> if (gnutls_x509_crt_init(&crt) < 0) { > >> error_setg(errp, "Failed to initialize certificate"); > >> return ret; > >> } > >> > >> rc = gnutls_x509_crt_import(crt, &datum, qcrypto_to_gnutls_cert_fmt_map[fmt]); > >> if (rc == GNUTLS_E_ASN1_TAG_ERROR) { > >> goto cleanup; > >> } > >> > >> ret = 0; > >> > >> cleanup: > >> gnutls_x509_crt_deinit(crt); > >> return ret; > >> } > >> > >> All it does with its @fmt argument is map it to the matching > >> GNUTLS_X509_FMT_*. > >> > >> There's just one caller, init_cert_x509_der() in hw/s390x/cert-store.c: > >> > >> is_der = qcrypto_check_x509_cert_fmt((uint8_t *)raw, size, > >> QCRYPTO_CERT_FMT_DER, &err); > >> > >> QCRYPTO_CERT_FMT_DER gets mapped to GNUTLS_X509_FMT_DER. Why not pass > >> that directly? We don't need enum QCryptoCertFmt then. > >> > > > > I received feedback on a previous patch series that directly using > > GNUTLS in QEMU code is discouraged, except for under the crypto/ > > directory. Internal APIs should be defined to access GNUTLS > > functionality instead. > > > >> If we need enum QCryptoCertFmt for some reason I can't see, why does it > >> have to be a QAPI type? Why not a plain C enum? > > > > While implementing the new helper functions, I referred to > > qcrypto_get_x509_cert_fingerprint() in crypto/x509-utils.c, which takes > > QCryptoHashAlgo as a parameter. Following this, I added corresponding > > QCRYPTO enums to map to GNUTLS enums. > > > > If using plain C enums is preferred, I can update the code accordingly > > in the next version. > > Use plain C enums when practical. > > Reasons for making a type a QAPI type include: > > * Some QAPI command or event needs it. > > * Something (typically QOM property accessors) needs the generated > visitor. > > * For enums: something could use the generated QEnumLookup / ENUM_str() > macro. Any time a method only accepts a subset of enum values, and needs to report an error message, it should always use ENUM_str in the error message, rather than the raw int value, to make the error message human friendly and invariant to enum ordering. IOW, ENUM_str should be relatively frequently used/needed. With 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 :|