Bug#724731: XDG_RUNTIME_DIR has incorrect value

[Gabriel Mainberger]

On 23.10.2013 16:18, Simon McVittie wrote:
> Making /run/user/${UID} writable by users other than ${UID} is probably
> a security vulnerability, so I would advise not doing that.

If course not. This is only a workaround to get X working again. But 
login direct as user avoid this workaround anyway.

>> Oct 23 15:08:03 machine su[5608]: pam_unix(su:session): session opened
>> for user gabriel by root(uid=0)
>> Oct 23 15:08:03 machine su[5608]: pam_systemd(su:session): Asking logind
>> to create session: uid=1000 pid=5608 service=su type=tty class=user
>> seat=seat0 vtnr=1 tty=/dev/tty1 display= remote=no remote_user=root
>> remote_host=
>> Oct 23 15:08:03 machine su[5608]: pam_systemd(su:session): Reply from
>> logind: id=c1 object_path=/org/freedesktop/login1/session/c1
>> runtime_path=/run/user/0 session_fd=6 seat=seat0 vtnr=1
>
> That doesn't look right - shouldn't systemd-logind be returning
> /run/user/1000 here? This might be a systemd-logind bug.

The same behavior is described in this case:

https://bugzilla.redhat.com/show_bug.cgi?id=753882

In my opinion this is a bug from systemd. Of course

su user

should preserve the environment variables, but

su - user

not.