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

On 06/29/2017 06:40 AM, Daniel P. Berrange wrote: > 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(a)redhat.com&gt; >>> --- >>> 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. This essentially what happens in virQEMUDriverConfigNew. The caveat here is that the default value for default_tls_x509_cert_dir (e.g. /etc/pki/qemu) is not checked for existence, rather it's assumed.

> 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. OK and that answers most of the questions I had... If the user changes "default_*" (as processed in virQEMUDriverConfigLoadFile) and it does not exist, then should startup fail?