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98cdabcd07
Validate basic tunnel encapsulation using ipip. Set up two namespaces connected by veth. Connect a client and server. Do this with and without bpf encap. Signed-off-by: Willem de Bruijn <willemb@google.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
83 lines
2 KiB
C
83 lines
2 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/* In-place tunneling */
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#include <linux/stddef.h>
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#include <linux/bpf.h>
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#include <linux/if_ether.h>
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#include <linux/in.h>
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#include <linux/ip.h>
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#include <linux/tcp.h>
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#include <linux/pkt_cls.h>
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#include <linux/types.h>
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#include "bpf_endian.h"
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#include "bpf_helpers.h"
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static const int cfg_port = 8000;
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static __always_inline void set_ipv4_csum(struct iphdr *iph)
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{
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__u16 *iph16 = (__u16 *)iph;
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__u32 csum;
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int i;
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iph->check = 0;
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#pragma clang loop unroll(full)
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for (i = 0, csum = 0; i < sizeof(*iph) >> 1; i++)
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csum += *iph16++;
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iph->check = ~((csum & 0xffff) + (csum >> 16));
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}
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SEC("encap")
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int encap_f(struct __sk_buff *skb)
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{
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struct iphdr iph_outer, iph_inner;
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struct tcphdr tcph;
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if (skb->protocol != __bpf_constant_htons(ETH_P_IP))
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return TC_ACT_OK;
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if (bpf_skb_load_bytes(skb, ETH_HLEN, &iph_inner,
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sizeof(iph_inner)) < 0)
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return TC_ACT_OK;
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/* filter only packets we want */
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if (iph_inner.ihl != 5 || iph_inner.protocol != IPPROTO_TCP)
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return TC_ACT_OK;
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if (bpf_skb_load_bytes(skb, ETH_HLEN + sizeof(iph_inner),
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&tcph, sizeof(tcph)) < 0)
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return TC_ACT_OK;
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if (tcph.dest != __bpf_constant_htons(cfg_port))
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return TC_ACT_OK;
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/* add room between mac and network header */
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if (bpf_skb_adjust_room(skb, sizeof(iph_outer), BPF_ADJ_ROOM_NET, 0))
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return TC_ACT_SHOT;
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/* prepare new outer network header */
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iph_outer = iph_inner;
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iph_outer.protocol = IPPROTO_IPIP;
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iph_outer.tot_len = bpf_htons(sizeof(iph_outer) +
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bpf_htons(iph_outer.tot_len));
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set_ipv4_csum(&iph_outer);
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/* store new outer network header */
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if (bpf_skb_store_bytes(skb, ETH_HLEN, &iph_outer, sizeof(iph_outer),
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BPF_F_INVALIDATE_HASH) < 0)
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return TC_ACT_SHOT;
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/* bpf_skb_adjust_room has moved header to start of room: restore */
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if (bpf_skb_store_bytes(skb, ETH_HLEN + sizeof(iph_outer),
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&iph_inner, sizeof(iph_inner),
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BPF_F_INVALIDATE_HASH) < 0)
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return TC_ACT_SHOT;
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return TC_ACT_OK;
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}
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char __license[] SEC("license") = "GPL";
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