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Szmigiero" , =?utf-8?Q?Daniel_P_=2E_Berrang=C3=A9?= Subject: Re: [RFC PATCH v2 8/8] migration/multifd: Add a compat property for TLS termination In-Reply-To: References: <20250207142758.6936-1-farosas@suse.de> <20250207142758.6936-9-farosas@suse.de> Date: Fri, 07 Feb 2025 15:40:31 -0300 Message-ID: <87y0yhlhsw.fsf@suse.de> MIME-Version: 1.0 Content-Type: text/plain X-Spamd-Result: default: False [-4.30 / 50.00]; BAYES_HAM(-3.00)[100.00%]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; RCVD_VIA_SMTP_AUTH(0.00)[]; ARC_NA(0.00)[]; MIME_TRACE(0.00)[0:+]; MISSING_XM_UA(0.00)[]; TO_DN_SOME(0.00)[]; MID_RHS_MATCH_FROM(0.00)[]; RCVD_TLS_ALL(0.00)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; RCPT_COUNT_THREE(0.00)[4]; RCVD_COUNT_TWO(0.00)[2]; FUZZY_BLOCKED(0.00)[rspamd.com]; TO_MATCH_ENVRCPT_ALL(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.de:mid, suse.de:email, imap1.dmz-prg2.suse.org:helo] Received-SPF: pass client-ip=2a07:de40:b251:101:10:150:64:2; envelope-from=farosas@suse.de; helo=smtp-out2.suse.de X-Spam_score_int: -43 X-Spam_score: -4.4 X-Spam_bar: ---- X-Spam_report: (-4.4 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_MED=-2.3, 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: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Peter Xu writes: > On Fri, Feb 07, 2025 at 11:27:58AM -0300, Fabiano Rosas wrote: >> We're currently changing the way the source multifd migration handles >> the shutdown of the multifd channels when TLS is in use to perform a >> clean termination by calling gnutls_bye(). >> >> Older src QEMUs will always close the channel without terminating the >> TLS session. New dst QEMUs treat an unclean termination as an >> error. Due to synchronization conditions, src QEMUs 9.1 and 9.2 are an >> exception and can put the destination in a condition where it ignores >> the unclean termination. For src QEMUs older than 9.1, we'll need a >> compat property on the destination to inform that the src does not >> terminate the TLS session. >> >> Add multifd_clean_tls_termination (default true) that can be switched >> on the destination whenever a src QEMU <9.1 is in use. > > Patch looks good. Though did you forget to add the compat entry? > Indeed. > I suggest we add it for all pre-9.2, in case whoever backports the recent > changes so it re-exposes again in any distro stables. > > IMHO it doesn't hurt us much to be always cautious on 9.1 and 9.2 too by > loosing the termination a bit. > Ok, I'll put it in hw_compat_9_2. >> >> Signed-off-by: Fabiano Rosas >> --- >> migration/migration.h | 33 +++++++++++++++++++++++++++++++++ >> migration/multifd.c | 8 +++++++- >> migration/multifd.h | 2 ++ >> migration/options.c | 2 ++ >> 4 files changed, 44 insertions(+), 1 deletion(-) >> >> diff --git a/migration/migration.h b/migration/migration.h >> index 4c1fafc2b5..77def0b437 100644 >> --- a/migration/migration.h >> +++ b/migration/migration.h >> @@ -443,6 +443,39 @@ struct MigrationState { >> * Default value is false. (since 8.1) >> */ >> bool multifd_flush_after_each_section; >> + >> + /* >> + * This variable only makes sense when set on the machine that is >> + * the destination of a multifd migration with TLS enabled. It >> + * affects the behavior of the last send->recv iteration with >> + * regards to termination of the TLS session. >> + * >> + * When set: >> + * >> + * - the destination QEMU instance can expect to never get a >> + * GNUTLS_E_PREMATURE_TERMINATION error. Manifested as the error >> + * message: "The TLS connection was non-properly terminated". >> + * >> + * When clear: >> + * >> + * - the destination QEMU instance can expect to see a >> + * GNUTLS_E_PREMATURE_TERMINATION error in any multifd channel >> + * whenever the last recv() call of that channel happens after >> + * the source QEMU instance has already issued shutdown() on the >> + * channel. >> + * >> + * Commit 637280aeb2 (since 9.1) introduced a side effect that >> + * causes the destination instance to not be affected by the >> + * premature termination, while commit 1d457daf86 (since 10.0) >> + * causes the premature termination condition to be once again >> + * reachable. >> + * >> + * NOTE: Regardless of the state of this option, a premature >> + * termination of the TLS connection might happen due to error at >> + * any moment prior to the last send->recv iteration. >> + */ >> + bool multifd_clean_tls_termination; >> + >> /* >> * This decides the size of guest memory chunk that will be used >> * to track dirty bitmap clearing. The size of memory chunk will >> diff --git a/migration/multifd.c b/migration/multifd.c >> index b4f82b0893..4342399818 100644 >> --- a/migration/multifd.c >> +++ b/migration/multifd.c >> @@ -1147,6 +1147,7 @@ void multifd_recv_sync_main(void) >> >> static void *multifd_recv_thread(void *opaque) >> { >> + MigrationState *s = migrate_get_current(); >> MultiFDRecvParams *p = opaque; >> Error *local_err = NULL; >> bool use_packets = multifd_use_packets(); >> @@ -1155,6 +1156,10 @@ static void *multifd_recv_thread(void *opaque) >> trace_multifd_recv_thread_start(p->id); >> rcu_register_thread(); >> >> + if (!s->multifd_clean_tls_termination) { >> + p->read_flags = QIO_CHANNEL_READ_FLAG_RELAXED_EOF; >> + } >> + >> while (true) { >> uint32_t flags = 0; >> bool has_data = false; >> @@ -1166,7 +1171,8 @@ static void *multifd_recv_thread(void *opaque) >> } >> >> ret = qio_channel_read_all_eof(p->c, (void *)p->packet, >> - p->packet_len, 0, &local_err); >> + p->packet_len, p->read_flags, >> + &local_err); >> if (!ret) { >> /* EOF */ >> assert(!local_err); >> diff --git a/migration/multifd.h b/migration/multifd.h >> index bd785b9873..cf408ff721 100644 >> --- a/migration/multifd.h >> +++ b/migration/multifd.h >> @@ -244,6 +244,8 @@ typedef struct { >> uint32_t zero_num; >> /* used for de-compression methods */ >> void *compress_data; >> + /* Flags for the QIOChannel */ >> + int read_flags; >> } MultiFDRecvParams; >> >> typedef struct { >> diff --git a/migration/options.c b/migration/options.c >> index 1ad950e397..feda354935 100644 >> --- a/migration/options.c >> +++ b/migration/options.c >> @@ -99,6 +99,8 @@ const Property migration_properties[] = { >> clear_bitmap_shift, CLEAR_BITMAP_SHIFT_DEFAULT), >> DEFINE_PROP_BOOL("x-preempt-pre-7-2", MigrationState, >> preempt_pre_7_2, false), >> + DEFINE_PROP_BOOL("multifd-clean-tls-termination", MigrationState, >> + multifd_clean_tls_termination, true), >> >> /* Migration parameters */ >> DEFINE_PROP_UINT8("x-throttle-trigger-threshold", MigrationState, >> -- >> 2.35.3 >>