| Commit message (Collapse) | Author | Age | Files | Lines |
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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. When doing so, change the
qatomic_load_acquire() to qatomic_read(): here we don't need any ordering
of memory accesses, but reading a flag. qatomic_read() would suffice
because it guarantees fetching from memory. Nothing else we should need to
order on memory access.
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.
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Juraj Marcin <jmarcin@redhat.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/r/20250918203937.200833-2-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
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We want some visibility on stderr when the GNUTLS thread
safety countermeasures are activated, to encourage people
to get the real fix deployed (once it exists). Some trace
points will also help if we see any further wierd crash
scenario we've not anticipated.
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/qemu-devel/20250718150514.2635338-5-berrange@redhat.com
[add missing include]
Signed-off-by: Fabiano Rosas <farosas@suse.de>
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When TLS 1.3 is negotiated on a TLS session, GNUTLS will perform
automatic rekeying of the session after 16 million records. This
is done for all algorithms except CHACHA20_POLY1305 which does
not require rekeying.
Unfortunately the rekeying breaks GNUTLS' promise that it is safe
to use a gnutls_session_t object concurrently from multiple threads
if they are exclusively calling gnutls_record_send/recv.
This patch implements a workaround for QEMU that adds a mutex lock
around any gnutls_record_send/recv call to serialize execution
within GNUTLS code. When GNUTLS calls into the push/pull functions
we can release the lock so the OS level I/O calls can at least
have some parallelism.
The big downside of this is that the actual encryption/decryption
code is fully serialized, which will halve performance of that
cipher operations if two threads are contending.
The workaround is not enabled by default, since most use of GNUTLS
in QEMU does not tickle the problem, only non-multifd migration
with a return path open is affected. Fortunately the migration
code also won't trigger the halving of performance, since only
the outbound channel diretion needs to sustain high data rates,
the inbound direction is low volume.
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Link: https://lore.kernel.org/qemu-devel/20250718150514.2635338-2-berrange@redhat.com
[add stub for qcrypto_tls_session_require_thread_safety; fix unused var]
Signed-off-by: Fabiano Rosas <farosas@suse.de>
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The correct way of calling qcrypto_tls_session_handshake() requires
calling qcrypto_tls_session_get_handshake_status() right after it so
there's no reason to have a separate method.
Refactor qcrypto_tls_session_handshake() to inform the status in its
own return value and alter the callers accordingly.
No functional change.
Suggested-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Acked-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
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QEMU's TLS session code provides no way to call gnutls_bye() to
terminate a TLS session. Callers of qcrypto_tls_session_read() can
choose to ignore a GNUTLS_E_PREMATURE_TERMINATION error by setting the
gracefulTermination argument.
The QIOChannelTLS ignores the premature termination error whenever
shutdown() has already been issued. This was found to be not enough for
the migration code because shutdown() might not have been issued before
the connection is terminated.
Add support for calling gnutls_bye() in the tlssession layer so users
of QIOChannelTLS can clearly identify the end of a TLS session.
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Acked-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
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GNUTLS doesn't know how to perform I/O on anything other than plain
FDs, so the TLS session provides it with some I/O callbacks. The
GNUTLS API design requires these callbacks to return a unix errno
value, which means we're currently loosing the useful QEMU "Error"
object.
This changes the I/O callbacks in QEMU to stash the "Error" object
in the QCryptoTLSSession class, and fetch it when seeing an I/O
error returned from GNUTLS, thus preserving useful error messages.
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
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The current TLS session I/O APIs just return a synthetic errno
value on error, which has been translated from a gnutls error
value. This looses a large amount of valuable information that
distinguishes different scenarios.
Pushing population of the "Error *errp" object into the TLS
session I/O APIs gives more detailed error information.
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
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The new `qcrypto_tls_session_check_pending` function allows the caller
to know if data have already been consumed from the backend and is
already available.
Signed-off-by: Antoine Damhet <antoine.damhet@shadow.tech>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
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Currently the TLS session object assumes that the caller will always
provide a hostname when using x509 creds on a client endpoint. This
relies on the caller to detect and report an error if the user has
configured QEMU with x509 credentials on a UNIX socket. The migration
code has such a check, but it is too broad, reporting an error when
the user has configured QEMU with PSK credentials on a UNIX socket,
where hostnames are irrelevant.
Putting the check into the TLS session object credentials validation
code ensures we report errors in only the scenario that matters.
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20220304193610.3293146-2-berrange@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
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Code consuming the "crypto/tlscreds*.h" APIs doesn't need
to access its internals. Move the structure definitions to
the "tlscredspriv.h" private header (only accessible by
implementations). The public headers (in include/) still
forward-declare the structures typedef.
Note, tlscreds.c and 3 of the 5 modified source files already
include "tlscredspriv.h", so only add it to tls-cipher-suites.c
and tlssession.c.
Removing the internals from the public header solves a bug
introduced by commit 7de2e856533 ("yank: Unregister function
when using TLS migration") which made migration/qemu-file-channel.c
include "io/channel-tls.h", itself sometime depends on GNUTLS,
leading to a build failure on OSX:
[2/35] Compiling C object libmigration.fa.p/migration_qemu-file-channel.c.o
FAILED: libmigration.fa.p/migration_qemu-file-channel.c.o
cc -Ilibmigration.fa.p -I. -I.. -Iqapi [ ... ] -o libmigration.fa.p/migration_qemu-file-channel.c.o -c ../migration/qemu-file-channel.c
In file included from ../migration/qemu-file-channel.c:29:
In file included from include/io/channel-tls.h:26:
In file included from include/crypto/tlssession.h:24:
include/crypto/tlscreds.h:28:10: fatal error: 'gnutls/gnutls.h' file not found
#include <gnutls/gnutls.h>
^~~~~~~~~~~~~~~~~
1 error generated.
Reported-by: Stefan Weil <sw@weilnetz.de>
Suggested-by: Daniel P. Berrangé <berrange@redhat.com>
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/407
Fixes: 7de2e856533 ("yank: Unregister function when using TLS migration")
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
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It's either "GNU *Library* General Public License version 2" or "GNU
Lesser General Public License version *2.1*", but there was no "version
2.0" of the "Lesser" license. So assume that version 2.1 is meant here.
Signed-off-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
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The 'qemu_acl' type was a previous non-QOM based attempt to provide an
authorization facility in QEMU. Because it is non-QOM based it cannot be
created via the command line and requires special monitor commands to
manipulate it.
The new QAuthZ subclasses provide a superset of the functionality in
qemu_acl, so the latter can now be deleted. The HMP 'acl_*' monitor
commands are converted to use the new QAuthZSimple data type instead
in order to provide temporary backwards compatibility.
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
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GNUTLS takes a paranoid approach when seeing 0 bytes returned by the
underlying OS read() function. It will consider this an error and
return GNUTLS_E_PREMATURE_TERMINATION instead of propagating the 0
return value. It expects apps to arrange for clean termination at
the protocol level and not rely on seeing EOF from a read call to
detect shutdown. This is to harden apps against a malicious 3rd party
causing termination of the sockets layer.
This is unhelpful for the QEMU NBD code which does have a clean
protocol level shutdown, but still relies on seeing 0 from the I/O
channel read in the coroutine handling incoming replies.
The upshot is that when using a plain NBD connection shutdown is
silent, but when using TLS, the client spams the console with
Cannot read from TLS channel: Broken pipe
The NBD connection has, however, called qio_channel_shutdown()
at this point to indicate that it is done with I/O. This gives
the opportunity to optimize the code such that when the channel
has been shutdown in the read direction, the error code
GNUTLS_E_PREMATURE_TERMINATION gets turned into a '0' return
instead of an error.
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20181119134228.11031-1-berrange@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
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gnutls 3.0.0 was released in 2011 and all the distros that are build
target platforms for QEMU [1] include it:
RHEL-7: 3.1.18
Debian (Stretch): 3.5.8
Debian (Jessie): 3.3.8
OpenBSD (ports): 3.5.18
FreeBSD (ports): 3.5.18
OpenSUSE Leap 15: 3.6.2
Ubuntu (Xenial): 3.4.10
macOS (Homebrew): 3.5.19
Based on this, it is reasonable to require gnutls >= 3.1.18 in QEMU
which allows for all conditional version checks in the code to be
removed.
[1] https://qemu.weilnetz.de/doc/qemu-doc.html#Supported-build-platforms
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
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Pre-Shared Keys (PSK) is a simpler mechanism for enabling TLS
connections than using certificates. It requires only a simple secret
key:
$ mkdir -m 0700 /tmp/keys
$ psktool -u rjones -p /tmp/keys/keys.psk
$ cat /tmp/keys/keys.psk
rjones:d543770c15ad93d76443fb56f501a31969235f47e999720ae8d2336f6a13fcbc
The key can be secretly shared between clients and servers. Clients
must specify the directory containing the "keys.psk" file and a
username (defaults to "qemu"). Servers must specify only the
directory.
Example NBD client:
$ qemu-img info \
--object tls-creds-psk,id=tls0,dir=/tmp/keys,username=rjones,endpoint=client \
--image-opts \
file.driver=nbd,file.host=localhost,file.port=10809,file.tls-creds=tls0,file.export=/
Example NBD server using qemu-nbd:
$ qemu-nbd -t -x / \
--object tls-creds-psk,id=tls0,endpoint=server,dir=/tmp/keys \
--tls-creds tls0 \
image.qcow2
Example NBD server using nbdkit:
$ nbdkit -n -e / -fv \
--tls=on --tls-psk=/tmp/keys/keys.psk \
file file=disk.img
Signed-off-by: Richard W.M. Jones <rjones@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
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It is very useful to know about TLS cert verification
status when debugging, so add a trace point for it.
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
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Modern gnutls can use a global config file to control the
crypto priority settings for TLS connections. For example
the priority string "@SYSTEM" instructs gnutls to find the
priority setting named "SYSTEM" in the global config file.
Latest gnutls GIT codebase gained the ability to reference
multiple priority strings in the config file, with the first
one that is found to existing winning. This means it is now
possible to configure QEMU out of the box with a default
priority of "@QEMU,SYSTEM", which says to look for the
settings "QEMU" first, and if not found, use the "SYSTEM"
settings.
To make use of this facility, we introduce the ability to
set the QEMU default priority at build time via a new
configure argument. It is anticipated that distro vendors
will set this when building QEMU to a suitable value for
use with distro crypto policy setup. eg current Fedora
would run
./configure --tls-priority=@SYSTEM
while future Fedora would run
./configure --tls-priority=@QEMU,SYSTEM
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
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The gnutls default priority is either "NORMAL" (most historical
versions of gnutls) which is a built-in label in gnutls code,
or "@SYSTEM" (latest gnutls on Fedora at least) which refers
to an admin customizable entry in a gnutls config file.
Regardless of which default is used by a distro, they are both
global defaults applying to all applications using gnutls. If
a single application on the system needs to use a weaker set
of crypto priorities, this potentially forces the weakness onto
all applications. Or conversely if a single application wants a
strong default than all others, it can't do this via the global
config file.
This adds an extra parameter to the tls credential object which
allows the mgmt app / user to explicitly provide a priority
string to QEMU when configuring TLS.
For example, to use the "NORMAL" priority, but disable SSL 3.0
one can now configure QEMU thus:
$QEMU -object tls-creds-x509,id=tls0,dir=/home/berrange/qemutls,\
priority="NORMAL:-VERS-SSL3.0" \
..other args...
If creating tls-creds-anon, whatever priority the user specifies
will always have "+ANON-DH" appended to it, since that's mandatory
to make the anonymous credentials work.
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
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Commit 57cb38b included qapi/error.h into qemu/osdep.h to get the
Error typedef. Since then, we've moved to include qemu/osdep.h
everywhere. Its file comment explains: "To avoid getting into
possible circular include dependencies, this file should not include
any other QEMU headers, with the exceptions of config-host.h,
compiler.h, os-posix.h and os-win32.h, all of which are doing a
similar job to this file and are under similar constraints."
qapi/error.h doesn't do a similar job, and it doesn't adhere to
similar constraints: it includes qapi-types.h. That's in excess of
100KiB of crap most .c files don't actually need.
Add the typedef to qemu/typedefs.h, and include that instead of
qapi/error.h. Include qapi/error.h in .c files that need it and don't
get it now. Include qapi-types.h in qom/object.h for uint16List.
Update scripts/clean-includes accordingly. Update it further to match
reality: replace config.h by config-target.h, add sysemu/os-posix.h,
sysemu/os-win32.h. Update the list of includes in the qemu/osdep.h
comment quoted above similarly.
This reduces the number of objects depending on qapi/error.h from "all
of them" to less than a third. Unfortunately, the number depending on
qapi-types.h shrinks only a little. More work is needed for that one.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
[Fix compilation without the spice devel packages. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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Clean up includes so that osdep.h is included first and headers
which it implies are not included manually.
This commit was created with scripts/clean-includes.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 1453832250-766-3-git-send-email-peter.maydell@linaro.org
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The qcrypto_tls_session_check_certificate() method was setting
an Error even when the ACL check suceeded. This didn't affect
the callers detection of errors because they relied on the
function return status, but this did cause a memory leak since
the caller would not free an Error they did not expect to be
set.
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
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Introduce a QCryptoTLSSession object that will encapsulate
all the code for setting up and using a client/sever TLS
session. This isolates the code which depends on the gnutls
library, avoiding #ifdefs in the rest of the codebase, as
well as facilitating any possible future port to other TLS
libraries, if desired. It makes use of the previously
defined QCryptoTLSCreds object to access credentials to
use with the session. It also includes further unit tests
to validate the correctness of the TLS session handshake
and certificate validation. This is functionally equivalent
to the current TLS session handling code embedded in the
VNC server, and will obsolete it.
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
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