On 19/10/2018 13:04, Daniel P. Berrangé wrote: > On Fri, Oct 19, 2018 at 12:02:57PM +0200, Philippe Mathieu-Daudé wrote: >> On 09/10/2018 15:04, Daniel P. Berrangé wrote: >>> From: "Daniel P. Berrange" <berra...@redhat.com> >>> >>> Add an authorization backend that talks to PAM to check whether the user >>> identity is allowed. This only uses the PAM account validation facility, >>> which is essentially just a check to see if the provided username is >>> permitted >>> access. It doesn't use the authentication or session parts of PAM, since >>> that's dealt with by the relevant part of QEMU (eg VNC server). >>> >>> Consider starting QEMU with a VNC server and telling it to use TLS with >>> x509 client certificates and configuring it to use an PAM to validate >>> the x509 distinguished name. In this example we're telling it to use PAM >>> for the QAuthZ impl with a service name of "qemu-vnc" >>> >>> $ qemu-system-x86_64 \ >>> -object tls-creds-x509,id=tls0,dir=/home/berrange/security/qemutls,\ >>> endpoint=server,verify-peer=yes \ >>> -object authz-pam,id=authz0,service=qemu-vnc \ >>> -vnc :1,tls-creds=tls0,tls-authz=authz0 >>> >>> This requires an /etc/pam/qemu-vnc file to be created with the auth >>> rules. A very simple file based whitelist can be setup using >>> >>> $ cat > /etc/pam/qemu-vnc <<EOF >>> account requisite pam_listfile.so item=user sense=allow >>> file=/etc/qemu/vnc.allow >>> EOF >>> >>> The /etc/qemu/vnc.allow file simply contains one username per line. Any >>> username not in the file is denied. The usernames in this example are >>> the x509 distinguished name from the client's x509 cert. >>> >>> $ cat > /etc/qemu/vnc.allow <<EOF >>> CN=laptop.berrange.com,O=Berrange Home,L=London,ST=London,C=GB >>> EOF >>> >>> More interesting would be to configure PAM to use an LDAP backend, so >>> that the QEMU authorization check data can be centralized instead of >>> requiring each compute host to have file maintained. >>> >>> The main limitation with this PAM module is that the rules apply to all >>> QEMU instances on the host. Setting up different rules per VM, would >>> require creating a separate PAM service name & config file for every >>> guest. An alternative approach for the future might be to not pass in >>> the plain username to PAM, but instead combine the VM name or UUID with >>> the username. This requires further consideration though. >>> >>> Signed-off-by: Daniel P. Berrange <berra...@redhat.com> >>> --- >>> authz/Makefile.objs | 3 + >>> authz/pamacct.c | 149 ++++++++++++++++++++++++++++++++++++++++ >>> authz/trace-events | 3 + >>> configure | 37 ++++++++++ >>> include/authz/pamacct.h | 100 +++++++++++++++++++++++++++ >>> qemu-options.hx | 35 ++++++++++ >>> 6 files changed, 327 insertions(+) >>> create mode 100644 authz/pamacct.c >>> create mode 100644 include/authz/pamacct.h > > [snip] > >> Since this one links another lib, can we have a simple unit test? > > I would like to have been able to test this, but AFAICT, it is not > possible to test without having the pam service config file added > into /etc/pam.d/, which we obviously can't do from a unit test > in QEMU :-(
It makes sens. Too bad. Thanks, Phil. > >> Reviewed-by: Philippe Mathieu-Daudé <phi...@redhat.com> >> Tested-by: Philippe Mathieu-Daudé <phi...@redhat.com> > > Regards, > Daniel >
