netdev - Re: [PATCH net-next 2/2] bpf: support ipv6 for bpf_skb_{set,get}_tunnel

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Date:	Sun, 10 Jan 2016 16:35:08 -0800
From:	Alexei Starovoitov <alexei.starovoitov@...il.com>
To:	Daniel Borkmann <daniel@...earbox.net>
Cc:	davem@...emloft.net, tgraf@...g.ch, netdev@...r.kernel.org
Subject: Re: [PATCH net-next 2/2] bpf: support ipv6 for
 bpf_skb_{set,get}_tunnel_key

On Mon, Jan 11, 2016 at 01:16:39AM +0100, Daniel Borkmann wrote:
> After IPv6 support has recently been added to metadata dst and related
> encaps, add support for populating/reading it from an eBPF program.
> 
> Commit d3aa45ce6b ("bpf: add helpers to access tunnel metadata") started
> with initial IPv4-only support back then (due to IPv6 metadata support
> not being available yet).
> 
> To stay compatible with older programs, we need to test for the passed
> structure size. Also TOS and TTL support from the ip_tunnel_info key has
> been added. Tested with vxlan devs in collect meta data mode with IPv4,
> IPv6 and in compat mode over different network namespaces.
> 
> Signed-off-by: Daniel Borkmann <daniel@...earbox.net>
...
>  struct bpf_tunnel_key {
>  	__u32 tunnel_id;
> -	__u32 remote_ipv4;
> +	union {
> +		__u32 remote_ipv4;
> +		__u32 remote_ipv6[4];
> +	};
> +	__u8 tunnel_tos;
> +	__u8 tunnel_ttl;
>  };

Acked-by: Alexei Starovoitov <ast@...nel.org>

was hoping that you would mention that people should upgrade
their llvm to 3.7 release or later, since old pre-release
had a bug when dealing with such structs and some
'lazy' folks may still be running some old version ;)

btw, three minor bugs were fixed after 3.7 was released.
llvm 3.7.1 and 3.8 have no known issues in bpf backend.