[systemd-devel] About systemd call dbus session bus

[Simon McVittie]

On 06/02/15 03:32, 张洋 wrote:
> dbus-daemon --session --print-address --fork > /tmp/session_amgr

This is a security flaw (the search keywords to look for are "symlink 
attack").

> export DBUS_SESSION_BUS_ADDRESS=`cat /tmp/session_amgr`

This only affects the environment of the shell script that is about to 
exit, rendering it relatively useless. To set an environment variable 
for systemd, use "systemctl import-environment DBUS_SESSION_BUS_ADDRESS" 
- but don't do that for the system instance of systemd, it is not 
appropriate for random system services to share a session bus.

The question to ask yourself when dealing with the session bus and 
system services, what does "session" mean on your platform, and whose 
session is it (as in which uid)? The right way to manage your session 
follows from the answers to those questions.

For an embedded system, you probably want the "user session" enhancement 
for dbus, which I'm currently upstreaming into dbus 1.9.x.

Regards,
     S

-- 
Simon McVittie
Collabora Ltd. <http://www.collabora.com/>