netdev - Re: [PATCH] netfilter: remove duplicate code

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Date:   Tue, 10 Aug 2021 03:35:10 +0900
From:   Kangmin Park <l4stpr0gr4m@...il.com>
To:     Pablo Neira Ayuso <pablo@...filter.org>
Cc:     Jozsef Kadlecsik <kadlec@...filter.org>,
        Florian Westphal <fw@...len.de>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        netfilter-devel@...r.kernel.org, coreteam@...filter.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] netfilter: remove duplicate code

I checked the Changes Requested state in patchwork.
But I have not received any review mails.
I wonder if there is any problem.
I'm sorry if you just review a little late due to a busy schedule.

Kangmin Park

2021년 8월 7일 (토) 오후 3:21, Kangmin Park <l4stpr0gr4m@...il.com>님이 작성:
>
> nf_nat_ipv4_fn() and nf_nat_ipv6_fn() call nf_nat_inet_fn().
> Those two functions are already contains routine that gets nf_conn
> object and checks the untrackable situation.
> So, the following code is duplicated.
>
> ```
> ct = nf_ct_get(skb, &ctinfo);
> if (!ct)
>         return NF_ACCEPT;
> ```
>
> Therefore, define a function __nf_nat_inet_fn() that has the same
> contents as the nf_nat_inet_fn() except for routine gets and checks
> the nf_conn object.
> Then, separate the nf_nat_inet_fn() into a routine that gets a
> nf_conn object and a routine that calls the __nf_nat_inet_fn().
>
> Signed-off-by: Kangmin Park <l4stpr0gr4m@...il.com>
> ---
>  include/net/netfilter/nf_nat.h |  5 +++++
>  net/netfilter/nf_nat_core.c    | 37 ++++++++++++++++++++++------------
>  net/netfilter/nf_nat_proto.c   |  4 ++--
>  3 files changed, 31 insertions(+), 15 deletions(-)
>
> diff --git a/include/net/netfilter/nf_nat.h b/include/net/netfilter/nf_nat.h
> index 987111ae5240..a66f617c5054 100644
> --- a/include/net/netfilter/nf_nat.h
> +++ b/include/net/netfilter/nf_nat.h
> @@ -100,6 +100,11 @@ void nf_nat_ipv6_unregister_fn(struct net *net, const struct nf_hook_ops *ops);
>  int nf_nat_inet_register_fn(struct net *net, const struct nf_hook_ops *ops);
>  void nf_nat_inet_unregister_fn(struct net *net, const struct nf_hook_ops *ops);
>
> +unsigned int
> +__nf_nat_inet_fn(void *priv, struct sk_buff *skb,
> +                const struct nf_hook_state *state, struct nf_conn *ct,
> +                enum ip_conntrack_info ctinfo);
> +
>  unsigned int
>  nf_nat_inet_fn(void *priv, struct sk_buff *skb,
>                const struct nf_hook_state *state);
> diff --git a/net/netfilter/nf_nat_core.c b/net/netfilter/nf_nat_core.c
> index 7de595ead06a..98ebba2c0f6d 100644
> --- a/net/netfilter/nf_nat_core.c
> +++ b/net/netfilter/nf_nat_core.c
> @@ -682,25 +682,15 @@ unsigned int nf_nat_packet(struct nf_conn *ct,
>  }
>  EXPORT_SYMBOL_GPL(nf_nat_packet);
>
>  unsigned int
> -nf_nat_inet_fn(void *priv, struct sk_buff *skb,
> -              const struct nf_hook_state *state)
> +__nf_nat_inet_fn(void *priv, struct sk_buff *skb,
> +                const struct nf_hook_state *state, struct nf_conn *ct,
> +                enum ip_conntrack_info ctinfo)
>  {
> -       struct nf_conn *ct;
> -       enum ip_conntrack_info ctinfo;
>         struct nf_conn_nat *nat;
>         /* maniptype == SRC for postrouting. */
>         enum nf_nat_manip_type maniptype = HOOK2MANIP(state->hook);
>
> -       ct = nf_ct_get(skb, &ctinfo);
> -       /* Can't track?  It's not due to stress, or conntrack would
> -        * have dropped it.  Hence it's the user's responsibilty to
> -        * packet filter it out, or implement conntrack/NAT for that
> -        * protocol. 8) --RR
> -        */
> -       if (!ct)
> -               return NF_ACCEPT;
> -
>         nat = nfct_nat(ct);
>
>         switch (ctinfo) {
> @@ -755,6 +745,26 @@ nf_nat_inet_fn(void *priv, struct sk_buff *skb,
>         nf_ct_kill_acct(ct, ctinfo, skb);
>         return NF_DROP;
>  }
> +EXPORT_SYMBOL_GPL(__nf_nat_inet_fn);
> +
> +unsigned int
> +nf_nat_inet_fn(void *priv, struct sk_buff *skb,
> +              const struct nf_hook_state *state)
> +{
> +       struct nf_conn *ct;
> +       enum ip_conntrack_info ctinfo;
> +
> +       ct = nf_ct_get(skb, &ctinfo);
> +       /* Can't track?  It's not due to stress, or conntrack would
> +        * have dropped it.  Hence it's the user's responsibilty to
> +        * packet filter it out, or implement conntrack/NAT for that
> +        * protocol. 8) --RR
> +        */
> +       if (!ct)
> +               return NF_ACCEPT;
> +
> +       return __nf_nat_inet_fn(priv, skb, state, ct, ctinfo);
> +}
>  EXPORT_SYMBOL_GPL(nf_nat_inet_fn);
>
>  struct nf_nat_proto_clean {
> diff --git a/net/netfilter/nf_nat_proto.c b/net/netfilter/nf_nat_proto.c
> index 48cc60084d28..897859730078 100644
> --- a/net/netfilter/nf_nat_proto.c
> +++ b/net/netfilter/nf_nat_proto.c
> @@ -642,7 +642,7 @@ nf_nat_ipv4_fn(void *priv, struct sk_buff *skb,
>                 }
>         }
>
> -       return nf_nat_inet_fn(priv, skb, state);
> +       return __nf_nat_inet_fn(priv, skb, state, ct, ctinfo);
>  }
>
>  static unsigned int
> @@ -934,7 +934,7 @@ nf_nat_ipv6_fn(void *priv, struct sk_buff *skb,
>                 }
>         }
>
> -       return nf_nat_inet_fn(priv, skb, state);
> +       return __nf_nat_inet_fn(priv, skb, state, ct, ctinfo);
>  }
>
>  static unsigned int
> --
> 2.26.2
>