On Tue, Mar 19, 2019 at 6:20 PM Stanislav Fomichev <sdf@xxxxxxxxxx> wrote:
>
> skb_net returns network namespace from the associated device or socket.
>
> This will be used in the next commit.
>
> I tried to inline it in skbuff.h, but I don't think it's feasible.
If so, is this helper necessary?
All existing cases that use it pass both skb_net(skb) and skb to the
flow dissector, so can continue to call it locally if new argument net
is NULL.
The new users are in patch 9/9 in the device drivers, but those should
pass the device pointer unconditionally.
> It depends on 'net/sock.h' for sock_net() and 'linux/netdevice.h' for
> dev_net(), both of which we don't include from 'linux/skbuff.h' (but
> both sock.h and netdevice.h include skbuff.h). I though about doing
> it as a macro/putting it somewhere else, but we will have
> skb_flow_dissect{_xyz} use it in the next commits.
>
> Signed-off-by: Stanislav Fomichev <sdf@xxxxxxxxxx>
> ---
> include/linux/skbuff.h | 2 ++
> net/core/skbuff.c | 16 ++++++++++++++++
> 2 files changed, 18 insertions(+)
>
> diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
> index e8c1d5b97f96..75e1d4d73cca 100644
> --- a/include/linux/skbuff.h
> +++ b/include/linux/skbuff.h
> @@ -1275,6 +1275,8 @@ static inline int skb_flow_dissector_bpf_prog_detach(const union bpf_attr *attr)
> }
> #endif
>
> +struct net *skb_net(const struct sk_buff *skb);
> +
> struct bpf_flow_keys;
> bool __skb_flow_bpf_dissect(struct bpf_prog *prog,
> const struct sk_buff *skb,
> diff --git a/net/core/skbuff.c b/net/core/skbuff.c
> index b413354ee709..d81f3a95fb4e 100644
> --- a/net/core/skbuff.c
> +++ b/net/core/skbuff.c
> @@ -5725,3 +5725,19 @@ void __skb_ext_put(struct skb_ext *ext)
> }
> EXPORT_SYMBOL(__skb_ext_put);
> #endif /* CONFIG_SKB_EXTENSIONS */
> +
> +/**
> + * skb_net - Return network namespace associated with skb.
> + * @skb: skb
> + *
> + * Returns pointer to struct net or NULL.
> + */
> +struct net *skb_net(const struct sk_buff *skb)
> +{
> + if (skb->dev)
> + return dev_net(skb->dev);
> + else if (skb->sk)
> + return sock_net(skb->sk);
> + return NULL;
> +}
> +EXPORT_SYMBOL(skb_net);
> --
> 2.21.0.225.g810b269d1ac-goog
>
