Be consistent creating all the libraries in the main meson.build file.

Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20201006125602.2311423-8-philmd@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

The requirement to specify the parent class type makes the macro
harder to use and easy to misuse (silent bugs can be introduced
if the wrong struct type is specified).

Simplify the macro by just not declaring any class struct,
allowing us to remove the class_size field from the TypeInfo
variables for those types.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Message-Id: <20200916182519.415636-3-ehabkost@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>

With gcrypt, most of the dispatch happens in the library,
so there aren't many classes to create.  However, we can
still create separate dispatch for CTR mode, and for
CONFIG_QEMU_PRIVATE_XTS, which avoids needing to check
for these modes at runtime.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

Use separate classes for each cipher entry point: des_rfb, des3,
aes128, aes192, aes256, cast128, serpent, and twofish.

Generate wrappers for XTS only for CONFIG_QEMU_PRIVATE_XTS.
This eliminates unreachable wrappers for DES_RFB, DES3 and
CAST128, which have blocksizes that do not allow XTS mode.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

We had a second set of function pointers in QCryptoCipherBuiltin,
which are redundant with QCryptoCipherDriver.  Split the AES and
DES implementations to avoid one level of indirection.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

Split into encrypt/decrypt functions, dropping the "enc" argument.
Now that the function is private to this file, we know that "len"
is a multiple of AES_BLOCK_SIZE.  So drop the odd block size code.

Name the functions do_aes_*crypt_cbc to match the *_ecb functions.
Reorder and re-type the arguments to match as well.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

By making the function private, we will be able to make further
simplifications.  Re-indent the migrated code and fix the missing
braces for CODING_STYLE.

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

There's no real reason we need two separate helper functions here.
Standardize on the function signature required for xts_encrypt.
Rename to do_aes_{en,de}crypt_ecb, since the helper does not
itself do anything with respect to xts.

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

We verified that the data block is properly sized modulo
AES_BLOCK_SIZE within qcrypto_builtin_cipher_{en,de}crypt.
Therefore we will never have to handle odd sized blocks.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

The class vtable should be set by the class initializer.
This will also allow additional subclassing, reducing the
amount of indirection in the hierarchy.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

Merge the allocation of "opaque" into the allocation of "cipher".
This is step one in reducing the indirection in these classes.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

This allows the in memory structures to be read-only.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

Allow the use in QCryptoCipher to be properly typed with
the opaque struct pointer.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

The fourth argument to xts_encrypt should be the decrypt
callback; we were accidentally passing encrypt twice.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

Both qemu/osdep.h and cipherpriv.h have already been
included by the parent cipher.c.

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

QEMU standard procedure for included c files is to use *.c.inc.
E.g. there are a different set of checks that are applied.

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

The check in the encode/decode path using full division has a
noticeable amount of overhead.  By asserting the blocksize is
a power of 2, we can reduce this check to a mask.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

If nettle is disabled and gcrypt enabled, the compiler and linker flags
needed for gcrypt are not passed.

Gnutls was also not added as a dependancy when gcrypt is enabled.

Attempting to add the library dependencies at the same time as the
source dependencies is error prone, as there are alot of different
rules for picking which sources to use, and some of the source files
use code level conditionals intead. It is thus clearer to add the
library dependencies separately.

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20200901133050.381844-2-berrange@redhat.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Tested-by: Alex Bennée <alex.bennee@linaro.org>
Tested-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Thomas Huth <thuth@redhat.com>

We do have a QCryptoTLSCipherSuites struct.  It must be used when
setting instance_size of the QOM type.  Luckily this never caused
problems because the QCryptoTLSCipherSuites struct has only a
parent_obj field and nothing else.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20200826171005.4055015-5-ehabkost@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

This shows how to do some "computations" in meson.build using its array
and dictionary data structures, and also a basic usage of the sourceset
module for conditional compilation.

Notice the new "if have_system" part of util/meson.build, which fixes
a bug in the old build system was buggy: util/dbus.c was built even for
non-softmmu builds, but the dependency on -lgio was lost when the linking
was done through libqemuutil.a.  Because all of its users required gio
otherwise, the bug was hidden.  Meson instead propagates libqemuutil's
dependencies down to its users, and shows the problem.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Meson doesn't enjoy the same flexibility we have with Make in choosing
the include path.  In particular the tracing headers are using
$(build_root)/$(<D).

In order to keep the include directives unchanged,
the simplest solution is to generate headers with patterns like
"trace/trace-audio.h" and place forwarding headers in the source tree
such that for example "audio/trace.h" includes "trace/trace-audio.h".

This patch is too ugly to be applied to the Makefiles now.  It's only
a way to separate the changes to the tracing header files from the
Meson rewrite of the tracing logic.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

The object_property_set_FOO() setters take property name and value in
an unusual order:

    void object_property_set_FOO(Object *obj, FOO_TYPE value,
                                 const char *name, Error **errp)

Having to pass value before name feels grating.  Swap them.

Same for object_property_set(), object_property_get(), and
object_property_parse().

Convert callers with this Coccinelle script:

    @@
    identifier fun = {
        object_property_get, object_property_parse, object_property_set_str,
        object_property_set_link, object_property_set_bool,
        object_property_set_int, object_property_set_uint, object_property_set,
        object_property_set_qobject
    };
    expression obj, v, name, errp;
    @@
    -    fun(obj, v, name, errp)
    +    fun(obj, name, v, errp)

Chokes on hw/arm/musicpal.c's lcd_refresh() with the unhelpful error
message "no position information".  Convert that one manually.

Fails to convert hw/arm/armsse.c, because Coccinelle gets confused by
ARMSSE being used both as typedef and function-like macro there.
Convert manually.

Fails to convert hw/rx/rx-gdbsim.c, because Coccinelle gets confused
by RXCPU being used both as typedef and function-like macro there.
Convert manually.  The other files using RXCPU that way don't need
conversion.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <20200707160613.848843-27-armbru@redhat.com>
[Straightforwad conflict with commit 2336172d "audio: set default
value for pcspk.iobase property" resolved]

Next few patches will expose that functionality to the user.

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20200608094030.670121-3-mlevitsk@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

This will be used first to implement luks keyslot management.

block_crypto_amend_opts_init will be used to convert
qemu-img cmdline to QCryptoBlockAmendOptions

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20200608094030.670121-2-mlevitsk@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

Since our format is consumable by the fw_cfg device,
we can implement the FW_CFG_DATA_GENERATOR interface.

Example of use to dump the cipher suites (if tracing enabled):

  $ qemu-system-x86_64 -S \
    -object tls-cipher-suites,id=mysuite1,priority=@SYSTEM \
    -fw_cfg name=etc/path/to/ciphers,gen_id=mysuite1 \
    -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>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Acked-by: Laszlo Ersek <lersek@redhat.com>
Message-Id: <20200623172726.21040-6-philmd@redhat.com>

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 library 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
guest firmware, via fw_cfg. The list is represented as an array
of bytes.

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).

The firmware uses the IANA_TLS_CIPHER array for configuring
guest-side TLS, for example in UEFI HTTPS Boot.

[Description from Daniel P. Berrangé, edited by Laszlo Ersek.]

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Acked-by: Laszlo Ersek <lersek@redhat.com>
Message-Id: <20200623172726.21040-2-philmd@redhat.com>

According to the gcrypt documentation it's intended that
gcry_check_version() is called with the minimum version of gcrypt
needed by the program, not the version from the <gcrypt.h> header file
that happened to be installed when qemu was compiled.  Indeed the
gcrypt.h header says that you shouldn't use the GCRYPT_VERSION macro.

This causes the following failure:

  qemu-img: Unable to initialize gcrypt

if a slightly older version of libgcrypt is installed with a newer
qemu, even though the slightly older version works fine.  This can
happen with RPM packaging which uses symbol versioning to determine
automatically which libgcrypt is required by qemu, which caused the
following bug in RHEL 8:

  https://bugzilla.redhat.com/show_bug.cgi?id=1840485



qemu actually requires libgcrypt >= 1.5.0, so we might put the string
"1.5.0" here.  However since 1.5.0 was released in 2011, it hardly
seems we need to check that.  So I replaced GCRYPT_VERSION with NULL.
Perhaps in future if we move to requiring a newer version of gcrypt we
could put a literal string here.

Signed-off-by: Richard W.M. Jones <rjones@redhat.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

Add the ability for the secret object to obtain secret data from the
Linux in-kernel key managment and retention facility, as an extra option
to the existing ones: reading from a file or passing directly as a
string.

The secret is identified by the key serial number. The upper layers
need to instantiate the key and make sure the QEMU process has access
permissions to read it.

Signed-off-by: Alexey Krasikov <alex-krasikov@yandex-team.ru>

 - Fixed up detection logic default behaviour in configure

Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

Create base class 'common secret'. Move common data and logic from
'secret' to 'common_secret' class. This allowed adding abstraction layer
for easier adding new 'secret' objects in future.
Convert 'secret' class to child from basic 'secret_common' with 'data'
and 'file' properties.

Signed-off-by: Alexey Krasikov <alex-krasikov@yandex-team.ru>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

In case of not using random-number needing feature, it makes sense to
skip RNG init too. This is especially helpful when QEMU is sandboxed in
Stubdomain under Xen, where there is very little entropy so initial
getrandom() call delays the startup several seconds. In that setup, no
random bytes are needed at all.

Signed-off-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

The only way object_property_add() can fail is when a property with
the same name already exists.  Since our property names are all
hardcoded, failure is a programming error, and the appropriate way to
handle it is passing &error_abort.

Same for its variants, except for object_property_add_child(), which
additionally fails when the child already has a parent.  Parentage is
also under program control, so this is a programming error, too.

We have a bit over 500 callers.  Almost half of them pass
&error_abort, slightly fewer ignore errors, one test case handles
errors, and the remaining few callers pass them to their own callers.

The previous few commits demonstrated once again that ignoring
programming errors is a bad idea.

Of the few ones that pass on errors, several violate the Error API.
The Error ** argument must be NULL, &error_abort, &error_fatal, or a
pointer to a variable containing NULL.  Passing an argument of the
latter kind twice without clearing it in between is wrong: if the
first call sets an error, it no longer points to NULL for the second
call.  ich9_pm_add_properties(), sparc32_ledma_realize(),
sparc32_dma_realize(), xilinx_axidma_realize(), xilinx_enet_realize()
are wrong that way.

When the one appropriate choice of argument is &error_abort, letting
users pick the argument is a bad idea.

Drop parameter @errp and assert the preconditions instead.

There's one exception to "duplicate property name is a programming
error": the way object_property_add() implements the magic (and
undocumented) "automatic arrayification".  Don't drop @errp there.
Instead, rename object_property_add() to object_property_try_add(),
and add the obvious wrapper object_property_add().

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20200505152926.18877-15-armbru@redhat.com>
[Two semantic rebase conflicts resolved]

We can delete the redundant type conversion if
we set the the AES_KEY parameter with 'const' in
qcrypto_cipher_aes_ecb_(en|de)crypt() function.

Reported-by: Euler Robot <euler.robot@huawei.com>
Signed-off-by: Chen Qun <kuhn.chenqun@huawei.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

Change condition from QCRYPTO_SECRET_FORMAT_RAW
to QCRYPTO_SECRET_FORMAT_BASE64 in if-operator, because
this is potential error if you add another format value.

Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Alexey Krasikov <alex-krasikov@yandex-team.ru>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

This fixes the condition-check done by the "loaded" property
getter, such that the property returns true even when the
secret is loaded by the 'file' option.

Signed-off-by: Tong Ho <tong.ho@xilinx.com>
Signed-off-by: Daniel P. Berrangé <berrange@redhat.com>

The qcow2 .bdrv_measure() code calculates the crypto payload offset.
This logic really belongs in crypto/block.c where it can be reused by
other image formats.

The "luks" block driver will need this same logic in order to implement
.bdrv_measure(), so extract the qcrypto_block_calculate_payload_offset()
function now.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20200221112522.1497712-2-stefanha@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

qcrypto_tls_creds_load_cert() passes uninitialized GError *gerr by
reference to g_file_get_contents().  When g_file_get_contents() fails,
it'll try to set a GError.  Unless @gerr is null by dumb luck, this
logs a ERROR_OVERWRITTEN_WARNING warning message and leaves @gerr
unchanged.  qcrypto_tls_creds_load_cert() then dereferences the
uninitialized @gerr.

Fix by initializing @gerr properly.

Fixes: 9a2fd434
Cc: "Daniel P. Berrangé" <berrange@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20191204093625.14836-2-armbru@redhat.com>
Acked-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>

The stubs mechanism relies on static libraries and compilation order,
which is a bit brittle and should be avoided unless necessary.
Replace it with Boolean operations on CONFIG_* symbols.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

qcrypto_random_*, AES and qcrypto_init do not need to be linked as a whole
and are the only parts that are used by user-mode emulation.  Place them
in libqemuutil, so that whatever needs them will pick them up automatically.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>