Re: [Qemu-devel] [PATCH 14/14] vnc: don't demote authentication protocol when disabling login

[Anthony Liguori]

On 08/24/2011 03:45 PM, Daniel P. Berrange wrote:
> On Wed, Aug 24, 2011 at 01:43:09PM -0500, Anthony Liguori wrote:
> > Currently when disabling login in VNC, the password is cleared out and the
> > authentication protocol is forced to AUTH_VNC.  If you're using a stronger
> > authentication protocol, this has the effect of downgrading your security
> > protocol.
> >
> > Fix this by only changing the authentication protocol if the current
> > authentication protocol is AUTH_NONE.  That ensures we're never downgrading.
> >
> > Reported-by: Daniel Berrange<address@hidden>
> > Signed-off-by: Anthony Liguori<address@hidden>
> > ---
> >   monitor.c |   18 ------------------
> >   qmp.c     |   19 +++++++++++++++++++
> >   ui/vnc.c  |    4 +++-
> >   3 files changed, 22 insertions(+), 19 deletions(-)
> >
> > diff --git a/monitor.c b/monitor.c
> > index 9801a2d..ad73bc5 100644
> > --- a/monitor.c
> > +++ b/monitor.c
> > @@ -1005,24 +1005,6 @@ static int do_quit(Monitor *mon, const QDict *qdict, 
> > QObject **ret_data)
> >       return 0;
> >   }
> >
> > -void qmp_change(const char *device, const char *target,
> > -                bool has_arg, const char *arg, Error **err)
> > -{
> > -    if (strcmp(device, "vnc") == 0) {
> > -        if (strcmp(target, "passwd") == 0 || strcmp(target, "password") == 0) {
> > -            if (!has_arg || !arg[0]) {
> > -                vnc_display_disable_login(NULL);
> > -            } else {
> > -                qmp_change_vnc_password(arg, err);
> > -            }
> > -        } else {
> > -            qmp_change_vnc_listen(target, err);
> > -        }
> > -    } else {
> > -        deprecated_qmp_change_blockdev(device, target, has_arg, arg, err);
> > -    }
> > -}
> > -
> >   static int set_password(Monitor *mon, const QDict *qdict, QObject **ret_data)
> >   {
> >       const char *protocol  = qdict_get_str(qdict, "protocol");
> > diff --git a/qmp.c b/qmp.c
> > index 73d6172..5674adc 100644
> > --- a/qmp.c
> > +++ b/qmp.c
> > @@ -16,6 +16,7 @@
> >
> >   #include "sysemu.h"
> >   #include "console.h"
> > +#include "blockdev.h"
> >
> >   NameInfo *qmp_query_name(Error **errp)
> >   {
> > @@ -42,3 +43,21 @@ void qmp_change_vnc_listen(const char *target, Error **err)
> >           error_set(err, QERR_VNC_SERVER_FAILED, target);
> >       }
> >   }
> > +
> > +void qmp_change(const char *device, const char *target,
> > +                bool has_arg, const char *arg, Error **err)
> > +{
> > +    if (strcmp(device, "vnc") == 0) {
> > +        if (strcmp(target, "passwd") == 0 || strcmp(target, "password") == 0) {
> > +            if (!has_arg || !arg[0]) {
> > +                vnc_display_disable_login(NULL);
> > +            } else {
> > +                qmp_change_vnc_password(arg, err);
> > +            }
> > +        } else {
> > +            qmp_change_vnc_listen(target, err);
> > +        }
> > +    } else {
> > +        deprecated_qmp_change_blockdev(device, target, has_arg, arg, err);
> > +    }
> > +}
> > diff --git a/ui/vnc.c b/ui/vnc.c
> > index fc3a612..ecb216f 100644
> > --- a/ui/vnc.c
> > +++ b/ui/vnc.c
> > @@ -2648,7 +2648,9 @@ int vnc_display_disable_login(DisplayState *ds)
> >       }
> >
> >       vs->password = NULL;
> > -    vs->auth = VNC_AUTH_VNC;
> > +    if (vs->auth == VNC_AUTH_NONE) {
> > +        vs->auth = VNC_AUTH_VNC;
> > +    }
> >
> >       return 0;
> >   }
>
> Thanks for making this change. The same also needs to be done in the
> 'vnc_display_password()' method.

Ack.

Regards,

Anthony Liguori

> Regards,
> Daniel