In qcrypto_tls_creds_get_path() coverity complains that
we are checking '*creds' for NULL, despite having
dereferenced it previously. This is harmless bug due
to fact that the trace call was too early. Moving it
after the cleanup gets the desired semantics.

In qcrypto_tls_creds_check_cert_key_purpose() coverity
complains that we're passing a pointer to a previously
free'd buffer into gnutls_x509_crt_get_key_purpose_oid()
This is harmless because we're passing a size == 0, so
gnutls won't access the buffer, but rather just report
what size it needs to be. We can avoid it though by
explicitly setting the buffer to NULL after free'ing
it.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

The qcrypto_tls_creds_x509_sanity_check() checks whether
certs exist by calling access(). It is valid for this
method to be invoked with certfile==NULL though, since
for client credentials the cert is optional. This caused
it to call access(NULL), which happens to be harmless on
current Linux, but should none the less be avoided.

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

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>

The QCryptoTLSCredsX509 object was not free'ing the allocated
gnutls_dh_params_t data when unloading the credentials

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

When encrypting/decrypting data, the plaintext/ciphertext
buffers are required to be a multiple of the cipher block
size. If this is not done, nettle will abort and gcrypt
will report an error. To get consistent behaviour add
explicit checks upfront for the buffer sizes.

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

If no IV is provided, then use a default IV of all-zeros
instead of crashing. This gives parity with gcrypt and
nettle backends.

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

Currently the choice of whether to use nettle or gcrypt is
made based on what gnutls is linked to. There are times
when it is desirable to be able to force build against a
specific library. For example, if testing changes to QEMU's
crypto code all 3 possible backends need to be checked
regardless of what the local gnutls uses.

It is also desirable to be able to enable nettle/gcrypt
for cipher/hash algorithms, without enabling gnutls
for TLS support.

This gives two new configure flags, which allow the
following possibilities

Automatically determine nettle vs gcrypt from what
gnutls links to (recommended to minimize number of
crypto libraries linked to)

 ./configure

Automatically determine nettle vs gcrypt based on
which is installed

 ./configure --disable-gnutls

Force use of nettle

 ./configure --enable-nettle

Force use of gcrypt

 ./configure --enable-gcrypt

Force use of built-in AES & crippled-DES

 ./configure --disable-nettle --disable-gcrypt

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

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>

If the administrator incorrectly sets up their x509 certificates,
the errors seen at runtime during connection attempts are very
obscure and difficult to diagnose. This has been a particular
problem for people using openssl to generate their certificates
instead of the gnutls certtool, because the openssl tools don't
turn on the various x509 extensions that gnutls expects to be
present by default.

This change thus adds support in the TLS credentials object to
sanity check the certificates when QEMU first loads them. This
gives the administrator immediate feedback for the majority of
common configuration mistakes, reducing the pain involved in
setting up TLS. The code is derived from equivalent code that
has been part of libvirt's TLS support and has been seen to be
valuable in assisting admins.

It is possible to disable the sanity checking, however, via
the new 'sanity-check' property on the tls-creds object type,
with a value of 'no'.

Unit tests are included in this change to verify the correctness
of the sanity checking code in all the key scenarios it is
intended to cope with. As part of the test suite, the pkix_asn1_tab.c
from gnutls is imported. This file is intentionally copied from the
(long since obsolete) gnutls 1.6.3 source tree, since that version
was still under GPLv2+, rather than the GPLv3+ of gnutls >= 2.0.

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

Introduce a QCryptoTLSCredsX509 class which is used to
manage x509 certificate TLS credentials. This will be
the preferred credential type offering strong security
characteristics

Example CLI configuration:

 $QEMU -object tls-creds-x509,id=tls0,endpoint=server,\
               dir=/path/to/creds/dir,verify-peer=yes

The 'id' value in the -object args will be used to associate the
credentials with the network services. For example, when the VNC
server is later converted it would use

 $QEMU -object tls-creds-x509,id=tls0,.... \
       -vnc 127.0.0.1:1,tls-creds=tls0

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>

Introduce a QCryptoTLSCredsAnon class which is used to
manage anonymous TLS credentials. Use of this class is
generally discouraged since it does not offer strong
security, but it is required for backwards compatibility
with the current VNC server implementation.

Simple example CLI configuration:

 $QEMU -object tls-creds-anon,id=tls0,endpoint=server

Example using pre-created diffie-hellman parameters

 $QEMU -object tls-creds-anon,id=tls0,endpoint=server,\
               dir=/path/to/creds/dir

The 'id' value in the -object args will be used to associate the
credentials with the network services. For example, when the VNC
server is later converted it would use

 $QEMU -object tls-creds-anon,id=tls0,.... \
       -vnc 127.0.0.1:1,tls-creds=tls0

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>

Introduce a QCryptoTLSCreds class to act as the base class for
storing TLS credentials. This will be later subclassed to provide
handling of anonymous and x509 credential types. The subclasses
will be user creatable objects, so instances can be created &
deleted via 'object-add' and 'object-del' QMP commands respectively,
or via the -object command line arg.

If the credentials cannot be initialized an error will be reported
as a QMP reply, or on stderr respectively.

The idea is to make it possible to represent and manage TLS
credentials independently of the network service that is using
them. This will enable multiple services to use the same set of
credentials and minimize code duplication. A later patch will
convert the current VNC server TLS code over to use this object.

The representation of credentials will be functionally equivalent
to that currently implemented in the VNC server with one exception.
The new code has the ability to (optionally) load a pre-generated
set of diffie-hellman parameters, if the file dh-params.pem exists,
whereas the current VNC server will always generate them on startup.
This is beneficial for admins who wish to avoid the (small) time
sink of generating DH parameters at startup and/or avoid depleting
entropy.

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

Future patches will be adding more crypto related APIs which
rely on QOM infrastructure. This creates a problem, because
QOM relies on library constructors to register objects. When
you have a file in a static .a library though which is only
referenced by a constructor the linker is dumb and will drop
that file when linking to the final executable :-( The only
workaround for this is to link the .a library to the executable
using the -Wl,--whole-archive flag, but this creates its own
set of problems because QEMU is relying on lazy linking for
libqemuutil.a. Using --whole-archive majorly increases the
size of final executables as they now contain a bunch of
object code they don't actually use.

The least bad option is to thus not include the crypto objects
in libqemuutil.la, and instead define a crypto-obj-y variable
that is referenced directly by all the executables that need
this code (tools + softmmu, but not qemu-ga). We avoid pulling
entire of crypto-obj-y into the userspace emulators as that
would force them to link to gnutls too, which is not required.

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

The qcrypto_cipher_decrypt_aes method was using the wrong
key material, and passing the wrong mode. This caused it
to incorrectly decrypt ciphertext.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Message-Id: <1437740634-6261-1-git-send-email-berrange@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Commit d3462e37 broke qcow2's encryption functionality by using encrypt
instead of decrypt in the wrapper function it introduces. This was found
by qemu-iotests case 134.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Daniel P. Berrange <berrange@redhat.com>

Calling a function pointer that was cast from an incompatible function
results in undefined behavior.  'void *' isn't compatible with 'struct
XXX *', so we can't cast to nettle_cipher_func, but have to provide a
wrapper.  (Conversion from 'void *' to 'struct XXX *' might require
computation, which won't be done if we drop argument's true type, and
pointers can have different sizes so passing arguments on stack would
bug.)

Having two different prototypes based on nettle version doesn't make
this solution any nicer.

Reported-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Message-Id: <1437062641-12684-3-git-send-email-rkrcmar@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

In nettle 3, cbc_encrypt() accepts 'nettle_cipher_func' instead of
'nettle_crypt_func' and these two differ in 'const' qualifier of the
first argument.  The build fails with:

  In file included from crypto/cipher.c:71:0:
  ./crypto/cipher-nettle.c: In function ‘qcrypto_cipher_encrypt’:
  ./crypto/cipher-nettle.c:154:38: error: passing argument 2 of
  ‘nettle_cbc_encrypt’ from incompatible pointer type
           cbc_encrypt(ctx->ctx_encrypt, ctx->alg_encrypt,
                                               ^
  In file included from ./crypto/cipher-nettle.c:24:0,
                   from crypto/cipher.c:71:
  /usr/include/nettle/cbc.h:48:1: note: expected
  ‘void (*)(const void *, size_t, uint8_t *, const uint8_t *)
  but argument is of type
  ‘void (*)(      void *, size_t, uint8_t *, const uint8_t *)

To allow both versions, we switch to the new definition and #if typedef
it for old versions.

Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Message-Id: <1436548682-9315-2-git-send-email-rkrcmar@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

This was dereferencing a pointer before checking if it was NULL.

Reported-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reported-by: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

If we are linking to gnutls already and gnutls is built against
nettle, then we should use nettle as a cipher backend in
preference to our built-in backend.

This will be used when linking against some GNUTLS 2.x versions
and all GNUTLS 3.x versions.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Message-Id: <1435770638-25715-7-git-send-email-berrange@redhat.com>
[Change "#elif" to "#elif defined". - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

If we are linking to gnutls already and gnutls is built against
gcrypt, then we should use gcrypt as a cipher backend in
preference to our built-in backend.

This will be used when linking against GNUTLS 1.x and many
GNUTLS 2.x versions.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Message-Id: <1435770638-25715-6-git-send-email-berrange@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Introduce a generic cipher API and an implementation of it that
supports only the built-in AES and DES-RFB algorithms.

The test suite checks the supported algorithms + modes to
validate that every backend implementation is actually correctly
complying with the specs.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Message-Id: <1435770638-25715-5-git-send-email-berrange@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

To prepare for a generic internal cipher API, move the
built-in D3DES implementation into the crypto/ directory.

This is not in fact a normal D3DES implementation, it is
D3DES with double & triple length modes removed, and the
key bytes in reversed bit order. IOW it is crippled
specifically for the "benefit" of RFB, so call the new
files desrfb.c instead of d3des.c to make it clear that
it isn't a generally useful impl.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Message-Id: <1435770638-25715-4-git-send-email-berrange@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

To prepare for a generic internal cipher API, move the
built-in AES implementation into the crypto/ directory

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Message-Id: <1435770638-25715-3-git-send-email-berrange@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Introduce a new crypto/ directory that will (eventually) contain
all the cryptographic related code. This initially defines a
wrapper for initializing gnutls and for computing hashes with
gnutls. The former ensures that gnutls is guaranteed to be
initialized exactly once in QEMU regardless of CLI args. The
block quorum code currently fails to initialize gnutls so it
only works by luck, if VNC server TLS is not requested. The
hash APIs avoids the need to litter the rest of the code with
preprocessor checks and simplifies callers by allocating the
correct amount of memory for the requested hash.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Message-Id: <1435770638-25715-2-git-send-email-berrange@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>