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Thu, 24 Sep 2020 15:12:02 -0700 (PDT) Subject: Re: [PATCH bpf-next 3/6] bpf: add redirect_neigh helper as redirect drop-in To: Daniel Borkmann , ast@kernel.org Cc: john.fastabend@gmail.com, netdev@vger.kernel.org, bpf@vger.kernel.org References: <721fd3f8d5cf55169561e59fdec5fad2e0bf6115.1600967205.git.daniel@iogearbox.net> From: David Ahern Message-ID: <09aedc04-ee19-e72d-9a8d-aa4be7551a53@gmail.com> Date: Thu, 24 Sep 2020 16:12:01 -0600 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 MIME-Version: 1.0 In-Reply-To: <721fd3f8d5cf55169561e59fdec5fad2e0bf6115.1600967205.git.daniel@iogearbox.net> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On 9/24/20 12:21 PM, Daniel Borkmann wrote: > diff --git a/net/core/filter.c b/net/core/filter.c > index 0f913755bcba..19caa2fc21e8 100644 > --- a/net/core/filter.c > +++ b/net/core/filter.c > @@ -2160,6 +2160,205 @@ static int __bpf_redirect(struct sk_buff *skb, struct net_device *dev, > return __bpf_redirect_no_mac(skb, dev, flags); > } > > +#if IS_ENABLED(CONFIG_IPV6) > +static int bpf_out_neigh_v6(struct net *net, struct sk_buff *skb) > +{ > + struct dst_entry *dst = skb_dst(skb); > + struct net_device *dev = dst->dev; > + const struct in6_addr *nexthop; > + struct neighbour *neigh; > + > + if (dev_xmit_recursion()) > + goto out_rec; > + skb->dev = dev; > + rcu_read_lock_bh(); > + nexthop = rt6_nexthop((struct rt6_info *)dst, &ipv6_hdr(skb)->daddr); > + neigh = __ipv6_neigh_lookup_noref_stub(dev, nexthop); > + if (unlikely(!neigh)) > + neigh = __neigh_create(ipv6_stub->nd_tbl, nexthop, dev, false); the last 3 lines can be replaced with ip_neigh_gw6. > + if (likely(!IS_ERR(neigh))) { > + int ret; > + > + sock_confirm_neigh(skb, neigh); > + dev_xmit_recursion_inc(); > + ret = neigh_output(neigh, skb, false); > + dev_xmit_recursion_dec(); > + rcu_read_unlock_bh(); > + return ret; > + } > + rcu_read_unlock_bh(); > + IP6_INC_STATS(dev_net(dst->dev), > + ip6_dst_idev(dst), IPSTATS_MIB_OUTNOROUTES); > +out_drop: > + kfree_skb(skb); > + return -EINVAL; > +out_rec: > + net_crit_ratelimited("bpf: recursion limit reached on datapath, buggy bpf program?\n"); > + goto out_drop; > +} > + ... > + > +#if IS_ENABLED(CONFIG_INET) > +static int bpf_out_neigh_v4(struct net *net, struct sk_buff *skb) > +{ > + struct dst_entry *dst = skb_dst(skb); > + struct rtable *rt = (struct rtable *)dst; please use container_of here; I'd like to see the typecasts get removed. > + struct net_device *dev = dst->dev; > + u32 hh_len = LL_RESERVED_SPACE(dev); > + struct neighbour *neigh; > + bool is_v6gw = false; > + > + if (dev_xmit_recursion()) > + goto out_rec;