Re: [PATCH net] l2tp: only return sessions of the given tunnel in l2tp_session_get()

[Hengyu Liang <hengyul@cs.unc.edu>]

Hi Guillaume,

Thanks for looking at this.

I wasn't sure about the intended semantics. l2tp.rst says "L2TPv3
session ids are unique across all tunnels", but it also says Linux
allows the same ID in different tunnels, told apart by sk, and
l2tp_session_register() still allows that for UDP encap.

The patch only changes callers of l2tp_session_get() that pass a
tunnel_id, and the result differs from v6.8:

 - pppol2tp_connect() for session 5 in tunnel 2 fails with EEXIST if
   tunnel 1 (another UDP socket) already has a connected session 5.
 - "ip l2tp del session tunnel_id 4 session_id 7" deletes tunnel 3's
   session 7 when only tunnel 3 has it. On v6.8 it fails. l2tp.rst
   describes CONN_ID there as the parent tunnel of the session.

Am I misreading the documentation, is the documentation out of date, or
is this behaviour not intended?

Thanks,
Hengyu