[libvirt] [PATCH 2/2] qemu: Check for existence of provided *_tls_x509_cert_dir

[Daniel P. Berrange]

On Thu, Jun 29, 2017 at 09:24:30AM +0200, Jiri Denemark wrote:
> On Wed, Jun 28, 2017 at 15:30:28 -0400, John Ferlan wrote:
> > https://bugzilla.redhat.com/show_bug.cgi?id=1458630
> > 
> > Introduce virQEMUDriverConfigSetCertDir which will handle reading the
> > qemu.conf config file specific setting for default, vnc, spice, chardev,
> > and migrate. Then if a setting was provided, validating the existence of
> > the directory and overwriting the default set by virQEMUDriverConfigNew.
> > 
> > Also update the qemu.conf description for default to indicate the consequences
> > if the default directory does not exist.
> > 
> > Signed-off-by: John Ferlan <jferlan at redhat.com>
> > ---
> >  src/qemu/qemu.conf   |  9 ++++++++-
> >  src/qemu/qemu_conf.c | 42 ++++++++++++++++++++++++++++++++++--------
> >  2 files changed, 42 insertions(+), 9 deletions(-)
> > 
> > diff --git a/src/qemu/qemu.conf b/src/qemu/qemu.conf
> > index e6c0832..737fa46 100644
> > --- a/src/qemu/qemu.conf
> > +++ b/src/qemu/qemu.conf
> > @@ -3,7 +3,7 @@
> >  # defaults are used.
> >  
> >  # Use of TLS requires that x509 certificates be issued. The default is
> > -# to keep them in /etc/pki/qemu. This directory must contain
> > +# to keep them in /etc/pki/qemu. This directory must exist and contain:
> >  #
> >  #  ca-cert.pem - the CA master certificate
> >  #  server-cert.pem - the server certificate signed with ca-cert.pem
> > @@ -13,6 +13,13 @@
> >  #
> >  #  dh-params.pem - the DH params configuration file
> >  #
> > +# If the directory does not exist or does not contain the necessary files,
> > +# QEMU domains will fail to start if they are configured to use TLS.
> > +#
> > +# In order to overwrite the default directory alter the following. If the
> > +# provided directory does not exist, then the setting reverts back to the
> > +# default /etc/pki/qemu.
> > +#
> 
> I don't think this is a good idea. We should use the directory a user
> specified in qemu.conf. If it doesn't exist, well things won't work.
> Sure, we can complain about it in the logs, but we should not fallback
> to any magic default in that case. Anyone setting a custom directory for
> TLS certificates does this because they want to use it. If the directory
> does not exist, it's either because they forgot to create it or they
> made a typo somewhere. It's very unlikely someone actually wants to use
> a default directory even though they set a custom one.
> 
> NACK

Agreed, I think we need to distinguish between the default dirs for each
settings, vs user specified dir for each setting.

ie, if the user has *not* set 'chardev_tls_x509_cert_dir' then its default
value is '/etc/pki/libvirt-chardev'. If that directory does not exist,
then falling back to "default_tls_x509_cert_dir" is good.

If the user *has* set 'chardev_tls_x509_cert_dir' and it does nto exist,
then we should report an hard error, preferrably at startup so the admin
sees their mistake immediately.

Regards,
Daniel
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