From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 33460CAC592 for ; Mon, 15 Sep 2025 18:33:57 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1uyE0G-0006In-EK; Mon, 15 Sep 2025 14:32:41 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1uyE0F-0006F2-3Q for qemu-devel@nongnu.org; Mon, 15 Sep 2025 14:32:39 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1uyE05-0002K6-Hv for qemu-devel@nongnu.org; Mon, 15 Sep 2025 14:32:37 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1757961141; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=r7sdjI5UJAzCMl9q8Cylr+GT8o3v+QIHTInZaiv3F5A=; b=i3toDosXyHVKZYP1GxVMbevkPdA3T8jqN1QqUGau5Eft4e+onK+xhdlEpgA68iBBVeGlK8 phRHjYGjeJcgBYyQFg/k6FC+ZXfoRF20E+JAwAL9wuiYghUJ+q6UmY5sqyMMRAV32MUA0L daZ/MIOeh0W5OVGMB6FBB4AkcAptnZk= Received: from mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-630-Gt8SA-XCNfGKoI_0Lto0MA-1; Mon, 15 Sep 2025 14:31:54 -0400 X-MC-Unique: Gt8SA-XCNfGKoI_0Lto0MA-1 X-Mimecast-MFC-AGG-ID: Gt8SA-XCNfGKoI_0Lto0MA_1757961109 Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 716061800451; Mon, 15 Sep 2025 18:31:45 +0000 (UTC) Received: from redhat.com (unknown [10.42.28.50]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id B41F11954126; Mon, 15 Sep 2025 18:31:43 +0000 (UTC) Date: Mon, 15 Sep 2025 19:31:39 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Peter Xu Cc: qemu-devel@nongnu.org, Juraj Marcin , Fabiano Rosas Subject: Re: [PATCH v2 1/3] io/crypto: Move tls premature termination handling into QIO layer Message-ID: References: <20250911212355.1943494-1-peterx@redhat.com> <20250911212355.1943494-2-peterx@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/2.2.14 (2025-02-20) X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 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: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.035, 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=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, SPF_HELO_PASS=-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 Fri, Sep 12, 2025 at 11:24:34AM -0400, Peter Xu wrote: > On Fri, Sep 12, 2025 at 12:18:18PM +0100, Daniel P. Berrangé wrote: > > On Thu, Sep 11, 2025 at 05:23:53PM -0400, Peter Xu wrote: > > > QCryptoTLSSession allows TLS premature termination in two cases, one of the > > > case is when the channel shutdown() is invoked on READ side. > > > > > > It's possible the shutdown() happened after the read thread blocked at > > > gnutls_record_recv(). In this case, we should allow the premature > > > termination to happen. > > > > > > The problem is by the time qcrypto_tls_session_read() was invoked, > > > tioc->shutdown may not have been set, so this may instead be treated as an > > > error if there is concurrent shutdown() calls. > > > > > > To allow the flag to reflect the latest status of tioc->shutdown, move the > > > check upper into the QIOChannel level, so as to read the flag only after > > > QEMU gets an GNUTLS_E_PREMATURE_TERMINATION. > > > > > > When at it, introduce qio_channel_tls_allow_premature_termination() helper > > > to make the condition checks easier to read. > > > > > > This patch will fix a qemu qtest warning when running the preempt tls test, > > > reporting premature termination: > > > > > > QTEST_QEMU_BINARY=./qemu-system-x86_64 ./tests/qtest/migration-test --full -r /x86_64/migration/postcopy/preempt/tls/psk > > > ... > > > qemu-kvm: Cannot read from TLS channel: The TLS connection was non-properly terminated. > > > ... > > > > > > In this specific case, the error was set by postcopy_preempt_thread, which > > > normally will be concurrently shutdown()ed by the main thread. > > > > > > Signed-off-by: Peter Xu > > > --- > > > include/crypto/tlssession.h | 7 +------ > > > crypto/tlssession.c | 7 ++----- > > > io/channel-tls.c | 21 +++++++++++++++++++-- > > > 3 files changed, 22 insertions(+), 13 deletions(-) > > > > Reviewed-by: Daniel P. Berrangé > > > > > diff --git a/include/crypto/tlssession.h b/include/crypto/tlssession.h > > > index 2f62ce2d67..6b4fcadee7 100644 > > > --- a/include/crypto/tlssession.h > > > +++ b/include/crypto/tlssession.h > > > @@ -110,6 +110,7 @@ > > > typedef struct QCryptoTLSSession QCryptoTLSSession; > > > > > > #define QCRYPTO_TLS_SESSION_ERR_BLOCK -2 > > > +#define QCRYPTO_TLS_SESSION_PREMATURE_TERMINATION -3 > > > > > > /** > > > * qcrypto_tls_session_new: > > > @@ -259,7 +260,6 @@ ssize_t qcrypto_tls_session_write(QCryptoTLSSession *sess, > > > * @sess: the TLS session object > > > * @buf: to fill with plain text received > > > * @len: the length of @buf > > > - * @gracefulTermination: treat premature termination as graceful EOF > > > * @errp: pointer to hold returned error object > > > * > > > * Receive up to @len bytes of data from the remote peer > > > @@ -267,10 +267,6 @@ ssize_t qcrypto_tls_session_write(QCryptoTLSSession *sess, > > > * qcrypto_tls_session_set_callbacks(), decrypt it and > > > * store it in @buf. > > > * > > > - * If @gracefulTermination is true, then a premature termination > > > - * of the TLS session will be treated as indicating EOF, as > > > - * opposed to an error. > > > - * > > > > > > Could you say something about QCRYPTO_TLS_SESSION_PREMATURE_TERMINATION > > being a possible return code here (no need to repost just for that). > > Definitely, I overlooked the doc there.. > > I'll squash this when repost: > > diff --git a/include/crypto/tlssession.h b/include/crypto/tlssession.h > index 6b4fcadee7..2e9fe11cf6 100644 > --- a/include/crypto/tlssession.h > +++ b/include/crypto/tlssession.h > @@ -273,7 +273,8 @@ ssize_t qcrypto_tls_session_write(QCryptoTLSSession *sess, > * > * Returns: the number of bytes received, > * or QCRYPTO_TLS_SESSION_ERR_BLOCK if the receive would block, > - * or -1 on error. > + * or QCRYPTO_TLS_SESSION_PREMATURE_TERMINATION if a premature termination > + * is detected, or -1 on error. > */ > ssize_t qcrypto_tls_session_read(QCryptoTLSSession *sess, > char *buf, ACK, > > > > > > * It is an error to call this before > > > * qcrypto_tls_session_handshake() returns > > > * QCRYPTO_TLS_HANDSHAKE_COMPLETE > > > @@ -282,7 +278,6 @@ ssize_t qcrypto_tls_session_write(QCryptoTLSSession *sess, > > > ssize_t qcrypto_tls_session_read(QCryptoTLSSession *sess, > > > char *buf, > > > size_t len, > > > - bool gracefulTermination, > > > Error **errp); > > > > > > /** > > > > > +static bool > > > +qio_channel_tls_allow_premature_termination(QIOChannelTLS *tioc, int flags) > > > +{ > > > + if (flags & QIO_CHANNEL_READ_FLAG_RELAXED_EOF) { > > > + return true; > > > + } > > > + > > > + if (qatomic_read(&tioc->shutdown) & QIO_CHANNEL_SHUTDOWN_READ) { > > > + return true; > > > + } > > > + > > > + return false; > > > +} > > > > > > static ssize_t qio_channel_tls_readv(QIOChannel *ioc, > > > const struct iovec *iov, > > > @@ -364,8 +377,6 @@ static ssize_t qio_channel_tls_readv(QIOChannel *ioc, > > > tioc->session, > > > iov[i].iov_base, > > > iov[i].iov_len, > > > - flags & QIO_CHANNEL_READ_FLAG_RELAXED_EOF || > > > - qatomic_load_acquire(&tioc->shutdown) & QIO_CHANNEL_SHUTDOWN_READ, > > > errp); > > > > > > The original code uses qatomic_load_acquire() while the new code > > uses qatomic_read() which imposes weaker ordering constraints. > > > > Does this matter ? I'm not familiar enough with atomics to say > > which we need here ? > > My bad, I explicitly changed it but I forgot to mention it in the commit > message. > > I don't think we need memory barriers here, because memory barriers are > only used to describe ordering of at least more than one memory operation. > Here we sololy want to read the flag which implies whether a shutdown READ > was initiated, so IMHO qatomic_read() is the thing we want. Comparing to > raw access to tioc->shutdown, it's almost "volatile" making sure we fetch > from memory, so when another thread modifies it on the fly we'll see. > > I'll explain it in the commit message when repost. Thanks, that all sounds good. 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 :|