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

[Eric Blake]

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.

> +
> +    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);
> 

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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