Re: [Qemu-devel] [PATCH 2/2] qga: add windows implementation for guest-set-time

[Lei Li]

On 03/12/2013 11:05 PM, Eric Blake wrote:
> On 03/12/2013 03:08 AM, Lei Li wrote:
> > Signed-off-by: Lei Li <address@hidden>
> > ---
> >   qga/commands-win32.c | 34 ++++++++++++++++++++++++++++++++++
> >   1 file changed, 34 insertions(+)
> >
> > +void qmp_guest_set_time(int64_t time_ns, Error **errp)
> > +{
> > +    SYSTEMTIME ts;
> > +    FILETIME tf;
> > +    LONGLONG time;
> > +
> > +    acquire_privilege(SE_SYSTEMTIME_NAME, errp);
> > +    if (error_is_set(errp)) {
> > +        error_setg(errp, "Failed to acquire privilege");
> > +        return;
> > +    }
> Earlier, you told me that acquire_privilege is auto-dropped after a
> successful SetSystemTime.  But here, you acquire the privilege...
>
> > +
> > +    if (time_ns < 0 || time_ns / 100 > INT64_MAX - W32_FT_OFFSET) {
> > +        error_setg(errp, "Time %" PRId64 "is invalid", time_ns);
> > +        return;
> ...then return early without ever relinquishing it.
>
> > +    }
> > +
> > +    time = time_ns / 100 + W32_FT_OFFSET;
> > +
> > +    tf.dwLowDateTime = (DWORD) time;
> > +    tf.dwHighDateTime = (DWORD) (time >> 32);
> > +
> > +    if (!FileTimeToSystemTime(&tf, &ts)) {
> > +        error_setg(errp, "Failed to convert system time");
> > +        return;
> > +    }
> I would reorder the acquire_privilege to here, to give us the best
> possible chance of avoiding a leak of privileges when the user passes
> bogus data.

It make sense, I should thought about this, thank you!

> > +
> > +    if (!SetSystemTime(&ts)) {
> > +        slog("guest-set-time failed: %d", GetLastError());
> > +        error_setg_errno(errp, errno, "Failed to set time to guest");
> > +        return;
> > +    }
> > +}
> > +
> >   int64_t qmp_guest_file_open(const char *path, bool has_mode, const char 
> > *mode, Error **err)
> >   {
> >       error_set(err, QERR_UNSUPPORTED);


--
Lei