From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Ahern Subject: Re: netns_id in bpf_sk_lookup_{tcp,udp} Date: Mon, 19 Nov 2018 12:54:55 -0700 Message-ID: References: <15bf5496-523f-564f-443e-f3262bb9e668@gmail.com> <90ae2d6b-049a-90a2-05e5-66700e885b39@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Cc: netdev , daniel@iogearbox.net, Nicolas Dichtel To: Joe Stringer Return-path: Received: from mail-pf1-f196.google.com ([209.85.210.196]:39823 "EHLO mail-pf1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730519AbeKTGUI (ORCPT ); Tue, 20 Nov 2018 01:20:08 -0500 Received: by mail-pf1-f196.google.com with SMTP id c72so10670369pfc.6 for ; Mon, 19 Nov 2018 11:54:58 -0800 (PST) In-Reply-To: Content-Language: en-US Sender: netdev-owner@vger.kernel.org List-ID: On 11/19/18 12:47 PM, Joe Stringer wrote: > On Mon, 19 Nov 2018 at 10:39, David Ahern wrote: >> >> On 11/19/18 11:36 AM, Joe Stringer wrote: >>> Hi David, thanks for pointing this out. >>> >>> This is more of an oversight through iterations, the runtime lookup >>> will fail to find a socket if the netns value is greater than the >>> range of a uint32 so I think it would actually make more sense to drop >>> the parameter size to u32 rather than u64 so that this would be >>> validated at load time rather than silently returning NULL because of >>> a bad parameter. >> >> ok. I was wondering if it was a u64 to handle nsid of 0 which as I >> understand it is a legal nsid. If you drop to u32, how do you know when >> nsid has been set? > > I was operating under the assumption that 0 represents the root netns > id, and cannot be assigned to another non-root netns. > > Looking at __peernet2id_alloc(), it seems to me like it attempts to > find a netns and if it cannot find one, returns 0, which then leads to > a scroll over the idr starting from 0 to INT_MAX to find a legitimate > id for the netns, so I think this is a fair assumption? > Maybe Nicolas can give a definitive answer; as I recall he added the NSID option. I have not had time to walk the code. But I do recall seeing an id of 0. e.g, on my dev box: $ ip netns vms (id: 0) And include/uapi/linux/net_namespace.h shows -1 as not assigned.