netdev - Re: netns_id in bpf_sk_lookup

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Message-ID: <954e5e2c-d72d-5a87-e050-3e550273cce0@gmail.com>
Date:   Tue, 20 Nov 2018 08:46:59 -0700
From:   David Ahern <dsahern@...il.com>
To:     nicolas.dichtel@...nd.com, Joe Stringer <joe@...d.net.nz>
Cc:     netdev <netdev@...r.kernel.org>, daniel@...earbox.net
Subject: Re: netns_id in bpf_sk_lookup_{tcp,udp}

On 11/20/18 2:05 AM, Nicolas Dichtel wrote:
> Le 20/11/2018 à 00:46, David Ahern a écrit :
> [snip]
>> That revelation shows another hole:
>> $ ip netns add foo
>> $ ip netns set foo 0xffffffff
> It also works with 0xf0000000 ...

yes, I realized last night I sent a bad example. I meant any negative
number besides -1

> 
>> $ ip netns list
>> foo (id: 0)
>>
>> Seems like alloc_netid() should error out if reqid < -1 (-1 being the
>> NETNSA_NSID_NOT_ASSIGNED flag) as opposed to blindly ignoring it.
> alloc_netid() tries to allocate the specified nsid if this nsid is valid, ie >=
> 0, else it allocates a new nsid (actually the lower available).
> This is the expected behavior.
> 
> For me, it's more an iproute2 problem, which parses an unsigned and silently
> cast it to a signed value.

so your intention is that any < 0 value means auto generate not just -1.