Re: [PATCH 00/12] Add kdbus implementation

[Simon McVittie <simon.mcvittie@collabora.co.uk>]

On 30/10/14 11:52, Tom Gundersen wrote:
> For example, if you want to get the audit identity
> bits, you can now get this attached securely by the kernel, at the
> time the message is sent, rather than having to firest get the peer's
> $PID from SCM_CREDENTIALS and then read the audit identity bits racily
> from /proc/$PID/loginuid and /proc/$PID/sessionid

... which dbus-daemon (traditional D-Bus) deliberately doesn't offer as
a feature, because we are not aware of any way to do that over Unix
sockets without a race condition; and if we can't have it securely, we
don't want to have it at all.
<https://bugs.freedesktop.org/show_bug.cgi?id=83499>
It would be great if kdbus can fix that omission.

Capabilities are in the same boat, and as a result, systemd can't
currently have D-Bus methods that can only be called with CAP_WHATEVER.

> * fewer userspace context switches
[...]
> * fewer message copies in userspace

Readers are probably already aware of this, but note that D-Bus is
designed to be usable between mutually distrusting processes, which is
why we use Unix sockets and a lot of copies, rather than mmap or something.

    S